01 - Handycam System

7/29/2019 01 - Handycam System

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Kod Kertas EE-010-3/M02/NO.1 Muka Surat: 1 drpd 38

Modul 02 - Kertas Penerangan Cawangan Pembangunan Kurikulum 2009 (Versi 1)

INSTITUT KEMAHIRAN BELIA NEGARAKEMENTERIAN BELIA DAN SUKAN MALAYSIA

KERTAS PENERANGAN

KURSUS ELECTRONIC AUDIO VIDEO SENIOR TECHNICIAN

TAHAP TIGA

DUTI 06 PERFORM AUDIO VISUAL EQUIPMENT REPAIR WORK

07 PERFROM PREVENTIVE MAINTENANCE

TASK 06.08 ~ REPAIR FAULTY HANDY CAM

07.03 ~ CARRY OUT HANDY CAM PREVENTIVE MAINTENANCE

OBJEKTIF PENCAPAIAN

PIAWAICARRY OUT HANDY CAM PREVENTIVE MAINTENANCE USINGMULTMETER HAND TOOLS,MAINTENANCE SCHEDULE,

MAINTENANCE MANUAL AND MAINTENANCE RECORD SO THATPREVENTIVE MAINTENANCE SCHEDDULE OBTAINED,PREVENTIVE MAINTENANCE ACTIVITIES EXECUTED,FUNCTIONALITY TEST CONDUCTED AND MAINTENANCE RECORDUPDATED IN ACCORDANCE WITH ESTABLISHED PROCEDURES.

TAJUK HANDY CAM

TUJUAN KERTAS PENERANGAN INI AKAN MENERANGKAN

Peralatan Video Kamera seperti pengunaan,system dan bahagian-bahagian yang terdapat di dalam system sesebuah video kamera.Melalui kertas penerangan ini pelatih-pelatih dapat memahami jenis danfungsi pealatan tersebut


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VIDEO CAMERAS AND CAMCORDERS

OBJECTIVES

Upon completion this chapter, the student is expected to comprehend:

1. How a video camera uses a transducer to convert images into electrical signals

corresponding to luminance and chrominance.

2. The operation of the most popular image sensor, the charge-coupled device (CCD).

3. How colors are separated by color filters and processed to form the Y and C signals for

transmission.

4. The characteristic gamma of a CRT and the gamma correction required by a video

camera.

5. Lenses and how to calculate f-stop values using focal length and lens size.

6. Camera features, including auto focus, character generators, macro, OSD, zoom, and

image stabilization.

The basic operation of a video camera begins within the camera, where light in the televised

scene converts to an electrical signal. In this process, the optical image focuses onto a

photosensitive target in the camera. The variations of light in the scene produce electrical

variations in charge, current, or resistance. These variations become a video signal.

Conversion of the entire scene into a video signal is accomplished by horizontal and vertical

scanning. As the scanning continues in sequential order, the light values for every point in the

scene are converted to signal output. The process is basically the same for color or monochrome

TV. In color TV, separate video signals are produced for the scene's reds, greens, and blues.

Figure 4-1 shows a common type of cam~ra pickup transduqer, the charge-coupled device(CCD). This solid-state CCD chip is the main part of the .camera. It works together with the

circuits needed to scan and process the video signal. Typically it is !/3 in., 1/2 in., or 2/3 in.

Prior to the CCD imaging sensor, cameras used vacuum tubes, such as the vidicon tubes in

Figure 4-2. Tube-type pickup cameras are still in use and they produce excellent results~ but the

cost of replacing the tubes nearly prohibits continuing maintenance of these units. In comparison to

tubes, CCDs cost less, are smaller, weigh less, work at lower voltages, use up less power, are

sturdier, and work longer.

Because early television cameras were all tube devices, these cameras were very large and could

be used only in studios with very bright lights, or outdoors. With the advent of solidstate transistors

and integrated circuits, cameras became smaller and lighter. During this same time, video tape

machines evolved from 1- and 2-inch tape into units using lA in. or narrower tape.

The size reduction of both the camera and video tape machines quickly lead to a merger of the two

into one compact unit called a camcorder.


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HOW A VIDEO CAMERA OPERATES

We take television for granted; but the ability to convert a picture to a video signal is a

fantastic technical achievement, especially using small portable cameras and camcorders.

Conversion of an optical image into an electrical video signal is accomplished by breaking thepicture into small areas, line by line and pixel by pixel in each line. As noted earlier, the pickup

device or image sensor may be either a tube or a solid-state device. Many tube devices give

excellent results; however, the many improvements of the CCD image sensor have made it

common in most applications.

Consumer electronics camcorders generally use a single CCD. In comparison, high-

end consumer and industrial applications use some single CCD pickups; but most will use a

threeCCD (three chip) image sensor system. Figure 4-4 shows an industrial-type camera.

Broadcast studios use a high-quality three-tube camera; or a three-CCD studio camera, like

the one in Figure 4-5.

How a TV camera works is illustrated in Figures 4-6 and 4-7. Figure 4-6 shows aportable camera televising a scene. The camera includes a pickup device, * such as a CCD,

with its associated signal-processing circuits. The camera is aimed at the scene so that the

optical image can be focused on the target of the pickup device. The resulting video signal

output is shown by the oscilloscope waveform (bottom left). Above the oscilloscope is the

monitor,

which shows the reproduced picture. .

Figure 4-7 details the video signal waveform. First, blanking pulses are added to the

camera signal. Blanking pulses make the signal amplitude go to the black level, so that the

retraces in scanning will not be visible. Then the synchronizing (sync) pulses are inserted.

Synchronization is needed to time the horizontal and vertical scanning.

The resulting camera signal with blanking and sync is called a composite video signal.

Sometimes, the term noncomposite video signal is used to identify the camera signal with

blanking but without sync. The standard output level of the composite video signal from the

camera is 1 V peak to peak (p-p), with the sync pulses in the down position, for negative

polarity.

Figure 4.1 a camera pickup transducer(Y2inch,

charge couple device, CCD). (lVC)


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Figure 4.2 A Vidicon tube, used in older camera

Figure 4.3a Consumer 8mm camcorder. (Panasonic)

Figure 4.3b Three-chip, Betacam broadcast camcorder for ENG used by a TV station

or production studio-15Ib.,7 oz.-work 75 minutes on one battery.


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Optical image

The optical image in Figure 4-7 is achieved using either a vidicon camera tube or CCD. The optical image

is focused on the front glass faceplate of the tube, or on the photodiodes of the CCD. The light strikes the

photoelectric image transducer, where light is converted into electrical signals. The optical lens produces

an inverted image of the scene on the rectangular area scanned by the electron beam. (An inverted image

is reversed right to left, and bottom to top.) Any convergent lens produces an inverted image. In this way,

the lens functions like a film camera, except that the focal plane is the image sensor instead of a film

surface.

In addition to forming the optical image, the lens regulates light by a mechanical iris built into the lens

housing. The iris adjusts the opening, or aperture, to determine how much light goes through the lens.

Just as in film cameras, the iris opening relates to / stops. In bright light, the iris closes down to reducethe total amount of light entering the camera. This situation corresponds to a larger f

Figure 4.3c Sony 3/CCD broadcast Camcorder.

Figure 4.4 A Camera using three Yl-in. CCD devices, ideal for computer

imaging, research, industrial inspection, or video conferencing.

(SONY)


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stop number. In darker scenes, the iris opens more to allow more light to enter the camera or camcorder.

This situation corresponds to a smaller / stop number.

Figure 4.5 A studio Camera using three V2 in, CCD image sensors, suitable for allType of shooting. (SONY)

Figure 4.6 TV Camera setup, shooting a black and white reflectance chart. The

oscilloscope waveform shows video signal output.


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l

Figure 4.7 Block diagram of how a tv camera supplies component video signal output

( deflection and focusing the camera tube are not shown)

PHOTOELECTRIC CONVERSION

Inside the photoelectric image sensor, the light image converts to an electric charge pattern.

The amount of charge for each picture element depends on the amount of light. This charge

pattern is scanned or clocked sequentially, so that the output image signal reproduces the

scene. This image output signal is produced by the image sensor device. Scanning is from

right to left and from bottom to top. (Remember, the image in the camera tube is inverted by

the lens.)

SIGNAL PROCESSING

The signal current from the camera pickup is small. The first stage in Figure 4-7 thus shows a

necessary preamplifier, as close as possible to the output terminal of the camera tube. The

amplifier has high gain but low noise. '

The electron scanning beam is cut off both during the retrace intervals for the horizontal lines

and also during the vertical retraces. Such blanking during retrace is necessary so that the

beam can swing back to its starting position without being visible. Retrace is also called flyback

because it is much faster than trace. The blanking level establishes a reference for the blacklevel.

After the preamplifier in Figure 4-7 are the functions of the signal processor and sync adder.

Signal processing corrects undesired shading in the picture and provides the desired contrast

ratio. Shading is produced because the characteristics of the photosensitive image plate are

not perfectly uniform over the entire surface.

It is necessary to obtain the desired contrast ratio, called the gamma correction, to

compensate for the fact that the image sensor emphasizes white when reproducing the

image. The correction is comparable to the idea of volume compression and expansion with

an audio signal.


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Final processing includes clamping of the blanked parts of the video signal to some referencevoltage level, followed by insertion of the synchronizing pulses. In effect, the blanking level is apedestal level at which the sync is added. The final result is the composite video signal,including camera signal variations, blanking pulses, and sync pulses. The standard output

level is 1 V p-p (as shown at the right in Figure 4-7) across a 75-fl load. Camera output circuits

are designed to drive 75-fl coaxial cable.

CAMERA AND MASTER CONTROL PANEL (MCP)

Studio cameras have two major sections, the camera and the control panel. The camera is the

business end. It contains the pickup device (or devices in many color cameras), clock or

deflection circuits and other circuits needed for the camera pickup, and the signal processing

circuits. .The master control panel (MCP), located in the control room console, contains interfaceconnections with the master sync generator; provision for remote control of the iris opening onthe camera lens; and circuits for setting the black level, gamma, white clip, color, and other

signal-processing needs.

The MCP supplies current to a tally lamp mounted on the camera to let operators know whichcamera is taking the picture. Also, the MCP has intercom connections with a headset jack onthe camera, which allows voice communications with the camera operator. When the camerais under control of the MCP, the operator has only to aim the camera, zoom, and check focus

THE EVOLUTION OF PICKUP DEVICES

Camera pickup devices have come a long way since the early days of mechanical scanning

with the Nipkowdisk. In that system, a photoelectric tube was combined with a rotating wheel(punched with small holes, spiraling toward the center) to scan the picture elements. The first

all-electric pickup devices were the image dissector and the iconoscope.

Improved types were the image iconoscope and the orthicon. The name orthicon indicates the

device s linear relation between light input and signal output. Television broadcasting from

about 1932 to 1945 used these tubes.

Another pickup device used then was the f1ying spot scanner. In this device, the spot of light

from the screen of a CRT was used as the light source to scan a film slide. The highly

sensitive image orthicon camera tube, developed in 1945, became-although large and

expensive-the workhorse of television for many years.

In the 1950s, the vidicon offered significantly better performance. It was photoconductive, rather

than photoemissive. Practically all TV applications used it, including broadcast units, small

portable cameras, and surveillance and industrial cameras. Even today they are used in some

cases; the six most common types, differing mainly by the composition of their target plates,

are vidicon, plumbicon, saticon, silicon vidicon, chalnicon, and newvicon. Clearly, target plates

are designed to work as well as possible in low-light situations. Also, their spectral response

must be wide enough to pickup various colors.

1. The vidicon, as can be seen in Figure 4-2, is small; its faceplate diameter is ~ in. Its

photosensitive target, or image plate, is made of antimony trisulfide.

2. The plumbicon is made by N. V. Phillips. Although similar to the vidicon, its image plate

is made of lead oxide (PbO). It is more sensitive to blue light than red.


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3. The saticon is made by Hitachi. Its image plate is made of selenium, arsenic, and

tellurium. This device has low image retention, often called image lag.

4. A silicon semiconductor junction is used for the target material in the silicon vidicon. Its

advantage is its high sensitivity in low-light scenes.

5. The highly sensitive chalnicon is made by Toshiba. Its target is in a complex, multilayer

arrangement, consisting of tin oxide, cadmium selenide, and arsenic trisulfide.

6. The newvicon is made by Matsushita Electric. Its target is an amorphous zinc-selenium

layer backed by antimony trisulfide. (Amorphous means the layer is not in a definite form,

both solid and liquid at the same time.) This sensitive device responds into the long-light

wavelengths for infrared.

Overall, the initial cost and cost of maintenance of these six types of vidicons have resulted in a

continuing decline in the number of units in use today.

CCD (CHARGE-COUPLED DEVICE)

The popular CCD (Figure 4-1) is a solid-state device using vertical columns and horizontal

rows of photodiodes to convert light into electrical charges. The charges are

stored and then transferred to the output stage of the device. The charges corresponding to the

light level are clocked out of the device as a video signal.

CCDs are better than tube devices. The newest cameras and camcorders use CCDs. They

cost less, are lighter, consume less power, last longer, avoid image bum, and have low lag

time. In addition, no high voltage section is needed

CHARGE-COUPLED PICKUP DEVICES (CCDs)

The CCD s image sensor function is performed by a columnar grid array of very small

photodiodes. The total number of photo diodes in the array can be in excess of 470,000 for a'1inch sensor! Each diode is a light- sensitive semiconductor. The diodes emit photoelectrons

proportional to the amount of the light they sense. When an optical image is focused onto the

diode array, the diodes produce a charge image that corresponds to the picture.

Each diode serves as one picture elemel1t (or pixel). A transfer operation is required to provide

signal output for all the pixels. This process corresponds to the scanning of an image by the

electron beam in a picture tube.

A high number of pixels results in the best picture resolution. Resolution is measured by

counting how much of the CCD area contains working pixels. As an example, what is the

resolution of Figure 4-1 s CCD, illustrated in Figure 4-8? The diagonal measurement of its

active area, shown in white, is Vi in. The number of horizontal pixels possible is 542, and the

total number of vertical pixels possible is 494.

However, the entire area is not active. The gray area, around the white active area, is used for

horizontal and vertical blanking. (This area for blanking periods also is used to reference optical

black.) The number of active pixels is found by multiplying 512 X 492; thus the

number of effective pixels is 251,904. Rounding upwards, we can say that the resolution of this

CCD pickup is approximately 252,000.

It is possible to have so many small photodiodes because they are etched into the chip by x


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ray. In contrast to Figure 4-8, a broadcast camera may have over 1000 in each horizontal row,

and over 500 in each vertical column, for an approximate resolution of half a million pixels!

Figure 4.8 a 1/3 in (4.82 mm width x 3.64 mm height) CCD image sensor.

The white area determines the number of active pixels

Figure 4-9 shows one pixel and the regions adjoining it. The area PD represents the

photodiode. How the sensor works, in short, is that when light strikes the PD, a charge

develops in proportion to the amount of received light. As the figure shows, the photodiode is

surrounded on three sides by a channel stopper (CS). The CS blocks the charge so that it

moves in only one direction. When the gate (G) opens, during the vertical retrace time, the

charge moves left to the VCCD (vertical charge-coupled device) area.

As shown in Figure 4-9, then, three steps are involved in reproducing the picture image. The

first step is photo conversion, which is produced by each of the photo diodes. The second is

charge storage of the photodiodes' output in the vertical shift register. The third is the transfer

of these charges to the output of the CCD chip. Let's examine these steps in more detail.

Figure 4-10 shows the CCD's structure. Vertically there are alternating columns of PDs

(photodiodes) and VCCDs (vertical charge-coupled devices shift registers). Recall from Figure

4-9 that there is a transfer gate between each photodiode and the vertical register. Because

each photodiode represents a pixel (picture element), in an image sensor there would be

several hundred photodiodes in each vertical column and in each horizontal row.

Figure 4.9 The structure of a CCD image sensor


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Looking again at Figure 4-10, observe that the image transfer process begins with the image

being focused on the entire matrix of photodiodes. Each diode becomes charged to a level

proportionate to the amount of light striking it.

As vertical blanking occurs, each of the transfer gates between the photodiodes and the

VCCDs are opened, allowing all of the charges to move into the VCCDs.

During horizontal blanking, one row of charges at a time is transferred down to the HCCD

(horizontal charge-coupled devices shift register).

During horizontal trace, the charges are moved, row by row, out of the HCCD. This action

corresponds to line-by-line scanning.

Movement out of the HCCD continues during vertical trace time, until all charges in the VCCD

have been transferred to the output.

At this time vertical retrace occurs, which resets the image sensor, allowing charges to begin

to accumulate in each of the PDs again. Storage is normally one field (one-half picture) at a

time

As vertical blanking ends, the transfer gates open, allowing all charges to move into the

VCCDs, and the whole process repeats.

As mentioned previously, storage is one field (one-half picture) at a time. By precise control of

the timing and phase of the drive signals, one field represents all of the even number lines and

the other field represents all of the odd number lines. Thus the two fields combine to form acomplete picture of 525 lines.

There are three ways to transfer the charges for the readout (the output signal), depending on

the architecture of the CCD. The three methods are frame transfer (FT), interline transfer (IT),

and frame interline transfer (FIT).

Output has two phases.

1. In the photoelectric phase, the optical image converts into a charge pattern. This analog

process creates a charge proportional in amount to the light input.

2. In the second phase, the charges transfer to the output. As shown in Figure 4-11, digital

switching-type drive circuits are driven from a clock generator. This operation is similartopulse amplitude modulation, in that each sample has a different amplitude level

HCCD

Figure 4.10 A model of a CCD sensor a few photodiodes in a 4:3 aspect ratio


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Figure 4.11 A CCD image sensors with its asscioated drive and output circuit

Using a digital sample process means that the picture information can be stored and

processed. Just before luminance and color processing, the sample and hold circuit (Figure 411) starts the process of converting the video signal back to a continuous analog signal.

OPTICAL COLOR SEPARATION

White light is composed of three primary colors: red, green, and blue. Our eyes do not respond

uniformly throughout the visible spectrum. Human vision peaks at the yellow-green

wavelengths. Our peak is at about 560 nanometers (nm).* In comparison, Figure 4-12 shows

the response of some camera pickup devices.

Obviously, cameras had to be developed to mimic our own range of color vision. We see

yellows and greens as the brightest colors. Thus the percentages of each of the primary colors

that matches the sensation of human vision is expressed by the signal equation.

Y = 30% red + 59% green + 11 % blue

or

Y = .30R + .59G + .liB

Because we see yellows and greens as brightest, a larger percentage is used in the equation

for the green primary signal. The Y signal is the luminance or brightness signal. This signal

equation produces a normal gray scale on a black-and-white picture tube or CRT.

Figure 4-13 illustrates a simple optical separator with color filters. Filters were used in older

cameras to separate the three primary colors. In the filter method, incoming light from the lensis split into three parts by partially silvered mirrors. The mirrors allow some of the light to pass,

but reflect the remainder. In front of each pickup device is an optical filter. These filters only

pass a narrow band of wavelengths centered on the red, green, and blue primary signals.

These filters block unwanted light. For example, the blue filter passes blue light, but it blocks

red and green. This simple scheme portrays the scene, but it is not very efficient because each

of the mirrors lose two-thirds of the total light reaching each pickup device.

As time passed, better filter techniques were developed


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The dichroic mirror technique solved the light-loss problem because these mirrors pass certain

wavelengths of light and reflect all others (Figure 4-14). The first mirror reflects blue and

passes the remainder of the wavelengths. The blue light is reflected by another mirror into theblue pickup. Note the blue flower pot is produced by this action. The light that passed through

the first dichroic mirror goes to the next dichroic mirror. Here red is reflected up to the red

pickup, where it outputs the red flower. The remainder of the light passes through this mirror

and strikes the green pickup, producing the green leaves and stems of the flower.

Figure 4.13 separator using optical red, green and blue filter for a color

camera

Figure 4.14 Color separator using dichroic mirrors. (a) Simplified views, showing separation

of red, green, and blue. (b) Phantom drawing of an actual camera (U.S lVC Corp.)


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Figure 4.14 Color separator using dichroic mirrors (a) Simplified views, showing separation ofred , green and blue (b) Phantom drawing of an actual camera ( U.SJVC Corp.)

Another method uses a prism, as shown in Figure 4-15. This system makes use of filtering

layers deposited on the surfaces of the prism. Prisms as photographic methods are said to be"faster" (less light lost through scattering) and have a lowerI-stop rating. Pickups are groupedaround the prism at angles, dictated by the angles at which the designated prism colorsemerge

Another type of filter, oblique color stripes, has been used with some single pickup device

cameras and camcorders to divide the light into red, green, and blue signals (Figure 4-16). The

striped filter is placed between the CCD pickup and the lens of the optical system. The color-

stripe filter is shown in Figure 4-16


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The oblique (diagonal) stripes for the color dissector are crisscrossed. Cyan and white stripes

slope downward from left to right in Figure 4-16a. Yellow and white stripes have the opposite

slope-upward from left to right. Yellow is a color mixture that contains red and green. The

cyan color mixture includes blue and green. (Green is in both ofthe color mixtures.)

Figure 4.15 Prism beam splitter for red, green blue light

With light input, the white stripes pass red, green, and blue. Yellow stripes pass onlyred and green. The cyan stripes pass only blue and green. Where the stripes cross, only green

passes through to the target plate of the camera tube.

Consider Figure 4-16 in detail. In 4-16c, point N represents one scanning line. As the beam

scans this line N, it passes only white and green, which is where the cyan and yellow overlap.

The white has red, green, and blue signals for the waveshapes in Figure 4-16c.

On the next scan line, labeled N+ 1, the beam passes yellow and cyan but no white. Yellow

has red and green signals for the waveshapes in Figure 4-16c, and cyan has blue and green

signals. In the waveforms, there is about a 90 phase difference between the stripe-signal

changes from line Nto line N+ 1.

Decoding of the signal is accomplished by storing a full scanning line of information in a time-delay device that inserts a lag of 63.5 (jus. This time, His the period of one full horizontal scan,

including retrace. Then the signal output of the delay line can be compared with the signal from

the scanning line that follows, because now they are lined up in time.

Delaying the phase of line N+ 1 by 90 and subtracting it from the 1 Hdelayed line, yields the

red signal. For the waveforms in Figure 4-16c, compare line TV + 1 in the second row

with the line N delayed by 90 in the third row. In the first sequence at the left, green is

subtracted from R+ G, leaving only the + Rsignal. For the next sequence to the right, REG is

subtracted from Band G. leaving only the -Rsignal. The result of the subtraction is shown by

the waveform in the fifth row.


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The same sequence is followed for all the lines. As a result, the camera produces + Band+ R signals from the individual color stripes. The G signal results from the colorintersections. The monochrome signal for the Yvideo signal is obtained by filtering outthe signal variations caused by the color stripes.

This camera also requires precise electrical focus. Poor focus can cause a greenbackground or no color. Precise control of the scanning width is also essential. An addedcomplication is the exact control of vertical deflection for the scanning height. Thescanning lines must be spaced as shown in Figure 4-16a, with respect to the crossing ofthe stripes.


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A color filter for a single CCO camera/camcorder is shown in Figure 4-17. A different color is

located above each photodiode in the CCO image sensor. The cyan filter passes blue and

green (B + G) and filters out red. The yellow filter passes red and green (R+ G) and filters out

blue. The magenta filter passes red and blue (R+ B) and filters out green. The fourth color filter

is green, so green (G) is passed, while red and blue are filtered out. Color plate VII shows howthe three primary colors of red, green, and blue relate to each other as they are mixed. Note

that cyan color is a mix of blue and green, which is why a cyan filter over the photodiode will

pass blue and green (B + G). Color plate VIII shows wavelength in nanometers, as wavelength

relates to colors in the visible spectrum. (Recall that maximum brightness to the human eye is

the yellow-green area of the spectrum.)

CCO image sensors have a wider wavelength response than the human eye, especially in the

longer wavelengths of 700 nanometers and greater. Wavelengths in this range are known as

infrared, or JR, signals. To maintain a response similar to the human eye, an IR filter is placed

in the light path in front of the CCO pickup. Wavelength and frequency are inversely

proportional to each other. In color plate VIII, observe that the area of 700 nanometers, or red,

corresponds to the lowest frequency. Frequencies lower than those for red will be in the

infrared region of the spectrum. High frequencies, shorter than 400 nanometers, correspond to

the ultraviolet region of the spectrum.

These four different color filters form a mosaic covering the entire surface of the CCO and

each of its photodiodes. The output results in two separate signals: the luminance signal (Y)

and the color signal (C).

The luminance signal is a mix of red, green, and blue, usually expressed as 2R+ 3G + 2J5.

The same luminance needs to be present in each line and field when the camera is pointed at

an evenly illuminatedobject. Figure 4-18 shows the even and odd fields. Starting at the left side

(the even-numbered line field) and moving to the right, line N is comprised of four color filters.

This arrangement can be expressed as TV = Mg+ Cy+ G + Ye; it then begins repeating over

and over. By substituting in the colors that are allowed to pass through each filter, the formula

for line Nof the even field is expressed as N= (R+ B) + (G + B) + G + (R

+ G). Solving this equation, we get N= 2R+ 3G + 2B, the value used for the luminance signal

(Y).

Starting at the left side of Figure 4-18 for line Nof the odd-numbered field and moving to the

right, the line (again) is comprised of four color filters. This arrangement can be expressed as

N- Cy+ Mg+ Ye + G; then it begins repeating over and over. By substituting the colors that

are allowed to pass through each of the color filters, the formula for line N of the odd field

becomes N= (G + B) + (R+ B) + (R+ G) + G. Solving this equation, we get N= 2R+ 3G +

2B. Notice that both TV lines for each of the two fields contain the same values of red, green,and blue. This situation proves that the luminance for each line and for each field is the same.

The same values will result for lines N+ 1, or any other lines across the surface of the CCO

pickup, thus providing a constant luminous level for each line and each field.

The color (C) signal, also called chrominance signal, is composed of two of the three colors for

processing purposes (the third signal is recovered later). The two signals that make up the

chrominance signal are the red and blue. The C signal is produced by subtracting Cy+ Mg

and the Ye + G filter colors; or the Cy + G and the Ye + Mgfilter colors. The image sensor

alternately produces Cy+ Mgand Ye + G at line Nof the odd field and line Nof the even field

due to the sensor's construction, as shown in Figure 4-18. (Compare the even and odd field

lines; these are the same, except in reverse. Because they are the same color filters, they

result in the same output.)


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Figure 4.18 A CCD color filter arrangements for scan line Nand N + 1 (for the old

and even fields).

These three outputs are shown in Figure 4: 19: the Yluminance (or brightness) signal passes

through the LPF (low-pass filter); and two C signals, R- Yand B - Y. are passed by the BPF(band-pass filter). Figure 4-20 shows the relative output of these three signals. Notice that theYsignal, when compared to color plate VIII, is in the yellow part of the spectrum

A circuit similar to Figure 4-19 will subtract these two signals, resulting in (Cy+ Mg) - (Ye + G).

By substituting in the colors passed by the filters (as shown in color plate VII), the formula is

shown as (G + B + R+ B) - (R+ G + G); solving, we get 2B - G. The next line, N

= 1 (as shown in Figure 4-18), will alternately produce Cy+ G and Ye + Mgfilter colors. Once

again, the circuit shown in Figure 4-19 will subtract these two signals, resulting in (Cy

+ G) - (Ye +A1g). Substituting in the colors passed by the filters, as shown in color plate VII,

the formula becomes (G + B + G) - (R+ G + R+ E); solving, we get G - 2R. (An inverter

function results in 2R- G.) The brightness characteristic of green is very close to the Ysignal.

So by substituting Yfor the G in the formula 2B - G. we see 2B - Yor simply B - Y. Likewise, by

substituting Yfor G in the formula 2R- G, we see 2R- Yor simply R- Y.

Figure 4.19 a circuit used to produce the Y (luminance) and the

C( color) signal.

R-Yred

Y

luminance

-Yblue


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Most cameras and camcorders, after the factory set-up adjustments, automatically perform

white balancing. This function is also known as auto white balance, or auto color temperature.

Some cameras have preset positions to correspond to various light sources. Figure 4-21

shows that different light sources have different brightness and color content characteristics,

given in degrees Kelvin. This function is normally routed through the main signal processorboard (or

I-C) with microprocessor control function. These auto white balance circuits adjust the gain of

the red (R - Y) and blue (B - Y) signals to equal the green or standard luminance signal of 2R +

3G + 2B (discussed in section 4-4). Some of the camcorders have a 2 position (or more)

switch, such as indoor or outdoor. However, most of the newer units have an auto position, and

many of the newest units use digital control circuits with the signals being processed through

software programs and CPU controllers.

GAMMA CORRECTION

The signal leaving the camera pickup is low level, approximately 200 m V. As previously

discussed, output consists of luminance (brightness) and chrominance (color). This output is

called a pre-video signal because it has no sync pulses. This pre-video (or preamplifier) signal

is passed through a pre-video (or preamplifier) process circuit, luminance process circuit, and

the chrominance process circuit (Figure 4-21).

Most cameras and camcorders use LSI (large-scale integration) ICs that have hundreds of

transistors and other circuit components forming complex circuits that perform many specific

functions (like white balance). The signal does not become full NTSC video until it has sync

pulses added and is fully processed to meet the standards set by the NTSC.

Gamma correction is one of the necessary functions of these video process circuits. Let'sexamine why more fully.

In the TV system there is a nonlinear relationship called gamma (y) between light values and

signal voltage at both the input (pickup device) and the output (picture tube) of the system.

The biggest offender is the picture tube in the TV set. Because of the operating characteristic

of the electron gun in the picture tube, the beam current and the resulting light output do not

vary uniformly with the drive voltage. They almost follow the squaring law: Light output varies

as the square of the video driving voltage. The overall effect is to compress blacks and stretch

whites.

This problem is not severe in black-and-white cameras, but it is extremely serious in color

cameras because errors in gamma produce serious errors in hue. To illustrate, a particularcolor may be made of one part red, two parts blue, and three parts green. If the system

effectively squares these values, the resulting light output is one part red, four parts blue, and

nine parts green, which produces a decidedly different color.

So gamma correction is one of the signal changes made in the signal processor. In color

cameras, correction is applied to all three channels.

The effect of gamma correction is illustrated in Figure 4-22. The gamma of the picture tube is

2.2. Therefore, the gamma needed for correction has the inverse value 1/2.2, which is 0.4545.

The gamma (y) values are exponents of epsilon (e), which is the natural base for logarithms or

exponents in the expression eY.


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F-STOP VALUES

The light-gathering ability of a camera is determined by the diameter of the lens. The larger the

lens diameter, the greater the amount of light falling on the target. Lenses are rated at

maximum diameter, for the biggest iris opening. The iris varies the opening for light to enter the

lens. Specifically, the / rating is

where F is the focal length and d is the diameter of the lens with the iris fully open. A longer

focal length means a higher value of f. However, a larger diameter corresponds to a smaller /-

stop.

The smaller the f rating. the more light the lens can take in. A low fnumber is needed whenlight is low in the scene. Highfnumbers can be used in bright sunshine.

A lens with a 13-mm diameter and a 25-mm focal length, for example, has anfrating of

f= E. = 25 mm = 1.9

d13mm

Such a lens would have 1.9 engraved on the iris ring, which lines up with an index mark when

the iris is fully open. The light input is controlled by closing the iris. The iris ring is calibrated

in.fstops, such as 1.9,2.8,4,5.6,8, 11, 16,22. Each of these calibration marks is called an.f stop.

The.f-stop numbers increase in steps of --./2, or approximately].4 ]4, so that each higher I-stopallows one-half the light input of the previous .fstop. Remember that the area of a circle is

proportional to the square of its diameter. Making the aperture smaller by "stopping dovm"

the iris to an effective diameter of11--./2reduces the light by half For example, an .f-stop of

2.8, multiplied by 1.4, equals 3.92, or 4, for the next higher fstop. Anfstop of 4 allows half the

light of the 2.8fstop.

In practice, the lens on the TV camera is stopped down until the brightest object in the scene

yields the standard I-V p-p video output. In many cameras, the iris is servo-controlled to

maintain this relationship.

Ff=d


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Figure 4.24 Focal length. (a) Video image taken with a 17mm wide-angle lens. (b) Video image

taken with a I02mm telephoto lens.

DEPTH OF FIELD

The lens opening affects depth of field. No doubt you have noticed that the background goes

out of focus in a TV scene when the camera is focused on a performer close to the camera.

The depth of field is the distance between the object in focus closest to the camera, and that

object farthest from the camera that rem,ains in focus. Actually there is only one focal

distance; but the depth of field is the distance that is discernible to the viewer.

At wide lens openings, the depth of field is poorest. This fact explains why lenses are stopped

down to higher numbers to allow the desired depth of field when enough light is available.

Still-picture photographers have another variable to work with. They can increase the

exposure time, trading exposure speed for depth of field, provided there is little or nomovement in the picture. But the exposure time is fixed at the frame rate in both motion

pictures and television. Therefore, the only variable left to manipulate is the lighting on the

subject. If the depth of field is to be increased, the lens must be stopped down and the amount

of light on the subject increased to compensate for the smaller aperture. Most consumer

camcorders (and many of the industrial and broadcast cameras or camcorders) have an

automatic iris that sets the I-stop automatically.

FOCAL LENGTH

Focal length determines the field of view for the lens. A short focal length gives a wide view.

For a close-up view, a longer focal length is used. These effects are shown in Figure 4-24.

ZOOM LENSES

The zoom lens has a continuously variable focal length. The use of zoom lenses is now almostuniversal in color productions, for they have replaced the optical turret of fixed-focal-lengthlenses found on older monochrome cameras. Figure 4-25a shows a power zoom lens from aportable camera with a motorized zoom adjustment. The taking angle can be "zoomed in" to aclose-up telephoto shot or zoomed out to a wide-angle view by the operator pressing therocker-type switch. The unit has been disassembled in Figure 4-25fo to show the motors thatdrive both the zoom mechanism and the automatic iris.


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Figure 4.25 (a) Power zoom lens. (b) Cover removed to show drive motor.

Zoom lenses are rated by the ratio between minimum and maximum focal lengths. For

example, the focal length of the lens used to take the pictures of Figure 4-24a and b varies

between 17 and 102 mm. The zoom range, then, is 102: 17 = 6: 1. Zoom lenses made for

cameras used in home camcorders are rated at 10: 1 to 24: 1. Those intended for commercial

TV applications range from 10:1 or more. The large zoom lenses, such as those used to cover

sports events, are extremely expensive because they are "fast" lenses with low I-stop ratings.

LIGHT

VALUES

The amount of light reflected from the subject into the camera is an important factor in

achieving low noise for a snow-free picture and in making the best use of the depth of field.

Although the camera works with reflected light, it has become traditional in TV operations touse incident light, the illumination falling on the subject.

Meters that measure illumination are readily available. Measurement of light values starts with

the source. The standard reference for luminous intensity, although somewhat obsolete, has

been the candle. The candela (cd) is a more recent unit based on electrically repeatable

devices and is practically equal to the candle. For a practical comparison, a small flashlight is

about 1-5 candlepower.

The light flux falling on a surface is directly proportional to the candlepower and inversely

proportional to the square of the distance. The light flux on the surface is its illumination. One

foot-candle (fc) is the light flux intercepted by a one-foot-square surface that is one foot from a

one-candlepower source. To calculate the illumination in foot-candles, divide the candlepowerof the source by the distance squared. For example, a 400-candlepower source that is 10ft.

from a surface provides this illumination:

400 400 = 4 f cL = 102 = 100


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The unit used in the metric system for illumination is the candela-meter, called a lux (Ix). If we

use the same numbers but convert feet to meters, the answer comes out in lux units. For

example, since 10ft. is

L = 400 = 400 = 44.4 lux

3 9The footcandle and the lux are both units of luminous flux, or illumination. Note that

footcandles and lux differ by an approximate factor of 10. This ratio is important because

specifications for most cameras are rated in lux. To convert lux to footcandles, divide by 10 for

approximate values (10.87, to be more exact). For these examples, 4 fc and 44 lux are

approximately equal. The footcandle is the larger unit.

Cameras are rated in minimum illumination required for a usable picture. Also, the illumination

required to meet certain performance specifications is usually given. For example, a

representative camcorder specifies minimum illumination as 10 lux, or less. Acceptable

pictures, with color, can be produced at extremely low-light levels. However,

signal-to-noise ratio is less than ideal and resolution suffers. As a practical comparison of light

flux, the desired illumination for reading is about 10 fc.

VIEWFINDERS

Like any camera, a video camera needs a viewfinder so that the operator will know what part of

the viewed scene is actually being converted to video information for transmission or video

taping. Some earlier systems used a separate, small-screen, black-and-white TV monitor

mounted in an assembly above the camera head. Viewfinders are driven directly from the

composite video output of the camera. This scene permits the operator of the camera to see

what the camera sees, for the purpose of subject framing. It allows the person to view the

focus either for manual setting or for observing the auto focus.Modem camcorders, either for consumer use or broadcast use, have built-in electronic

viewfinders. So, in effect, a camcorder actually consists of three parts: the video camera, the

magnetic tape recorder, and the viewfinder.

Figure 4-26 shows the block diagram of a tube-type electronic viewfinder, a small, black-and-

white monitor. (Newer camcorders are using LCD-liquid-crystal display-units that allow the

operator to view the taped or televised scene in full NTSC color.) The display is an integrated

matrix using thin-film construction with built-in vertical and horizontal shift registers. The display

provides drive for each of the pixels. As is shown in Figure 4-27, these viewfinders vary from 4

in. to as small as a %-in. diagonal measurement. Viewfinders may have in excess of 100,000

pixels forming the color display. These displays usually use the delta pattern, like the older-stylepicture tubes, to help reduce some color distortions. Again, like any solid-state device, they are

very reliable and do not require high voltages like the

CRT-type viewfinders. As with all LCDs, a backlight, which is necessary to use many of these

viewfinders, is a heavy power draw on the system battery.


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SPECIAL FEATURES

Although many "special" features are standard on many camcorders, they are not absolutely

essential to the basic operation of a unit, so we are discussing them separately. The

technology of high-density integration, mass production to meet consumer demand, and the

resulting relative low cost have made these features readily available.

AUTOFOCUS

Auto focus was mentioned earlier in the chapter. This feature produces sharp focus of thescene being viewed or taped. One method uses an IR (infrared) LED as the source for an

"invisible" beam. This beam first strikes the viewed object. It is reflected back to the

camera/camcorder to an infrared diode sensor array, where the output drives a Comparator IC

that controls a focus servo-motor. This method thus takes a few seconds.

Other methods of auto focus go for maximum-image contrast and/or sharpness of the pre-

video signal. New methods use digital signal-processing of the original, peak-detected signal to

drive the focus servo-motor.

Some of the full-range auto focus methods maintain extremely sharp focus, from macro

(extremely close-up) to infinity. These methods may require two focus servo-motors; one to

position the master lens, and the other to position the zoom lens. Figure 4-25 shows a mo-torized zoom lens.


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ON-SCREEN DISPLAY

At the touch of a button, an operator can turn on the date or time (or both) to be recorded on the

televised or recorded scene. Other on-screen displays allow the operator to program-in text,

such as the age of a person during a televised birthday party.

ELECTRONIC-IMAGE STABILIZATION

Small, light camcorders are hard to hold steady, especially when using zoom. Industrial and

broadcast camcorders, being heavier, are easier to hold. They fit on the shoulder of the

operator. Of course, an owner of a small camcorder could mount the unit on a large and heavy

tripod, like at TV studios. But that would defeat the purpose of portability!

To help, new units have an electronic circuit to stabilize the picture. These circuits sample the

picture, digitize it to memory, sample again, and compare the two signals. If the circuit detects

any change in position, the control microprocessor changes the data stream to the verticaland/or horizontal CCD shift register. This method corrects for picture movement.

Early stabilizing systems used active picture elements to sense and compare. Today's units

use larger-format CCDs. These units monitor for movement in areas not used for active NTSC

picture elements.

ZOOM

Using zoom, an operator can film far-away objects as if they were up close. Many zoom

features are digital in nature. Zoom values of 6: 1 or 8: 1 used to be standard. Popular today are

values of 12:1 to 24:1. As mentioned earlier, any movement of the camera/camcorder will bemagnified.

ADJUSTMENTS

In the United States, almost all standard adjustments for cameras and camcorders are

compatible with NTSC (National Television Systems Committee) standards. The standard for

composite video is 1000 mV, or 1 V p-p with negative sync. This standard is also known as

140 IRE units (Figure 4-28). Notice that zero m V is equivalent to zero IRE units. This zero level

is the video blanking level. Peak sync is negative 40 IRE units, equivalent to negative 286 mV

(see the CRT display in Figure 4-29). Notice the peak white level is 100 IRE units or positive714 mV; this is a total of 140 IRE units, or 1,000 mY

Cameras and camcorders are very reliable. They are factory-set to meet NTSC standards.

However, from time to time they need service repairs and then should be checked for proper

operation. These adjustments should be done carefully, following the manufacturers service

manual. Some special service equipment is required to check for proper signals and also to

observe while making adjustments. Some of the more common tests and adjustments can be

made using camera test equipment (Figure 4-30). The frequency of the burst reference needs

to be set at 3.579545 MHz. The luminance level can be tested to ensure 7.5 IRE units for black

setup and 100 IRE units for peak white level.


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The tape-recorder portion of a camcorder will be covered in a later chapter dealing with

videocassette recorders.

A functional universal block diagram, such as the one shown in Figure 4-33, can be used to

help understand the overall operation of a video camera or the camera portion of a camcorder.

If possible, a service technician should have the block diagram, schematic, diagram, circuit

description, test procedures and adjustments, along with any other pertinent informationincluded in the full service manual for the specific make and model being serviced and/or

calibrated. But, even with all of the above information, the technician needs good test

equipment such as that shown in Figures 4-30 and 4-31. Also helpful for a technician would be

troubleshooting flowcharts (Figure 4-34). These charts help to isolate the problem to a section,

or to a specific level for further troubleshooting.

Figure 4.32 Vectorscope display,. The CRT vector graticule is used in the vector/phaseor vector/amplitude mode to visually evaluate the phase and/or amplitudeof the vector color bar display. The middle of each of the inner targetboxes marks the EtA broadcasting standard for the phase and amplitudeof each of the colors of a color bar signal


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Figure 4.33 A universal video block diagram showing the functional block for process and

control.


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Figure 4.34 Camera troubleshooting flowchart to help isolate trouble to a specific section.

STUDIO AND FIELD APPLICATIONS

Studio operations have evolved steadily from the time when TV was "live" to now-when nearly

all programs are recorded on videotape. The videotape permits careful editing of program

material prior to actual airing. Even news programs are taped and edited before air time.

The constant improvement and the lower cost of videotape have resulted in a gradual return tooperations more like those used in motion-picture production. That is, a single camera drives asingle tape recorder. Actual assembly of the program from "cuts" made in this way isperformed by videotape editors, who make an electronic splice between program cuts.Mechanical editing (the cut-and-splice system used for film) is not used in TV production.Instead, material to be deleted is just erased from the videotape

However, many studio operations still use several cameras for TV productions. In this case,

the switching between cameras is done "live."

SYNCHRONIZED CAMERAS

In a multiple-camera system, the H and V scan rates of all cameras must be synchronized

precisely. There are two ways to do this synchronization. In the older method, a mastersynchronizing generator supplied the H and V drive to all cameras in the system. The video


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outputs of all cameras were brought together to a switcher-fader. Today, outputs go to a

special-effects generator (SEG), which is also a production switcher. The switcher permits in-

dividual camera outputs to be switched to the program line, the final output of the system that is

routed to a videotape recorder or the transmission system.

Switching is not done by a simple mechanical switch because a glitch (a spurious pulse) would

appear in the picture at the instant that the switch is made. Instead, an electronic switch is held

off until the next vertical blanking period arrives. With vertical-interval switching, the change is

made when all the monitors or receivers fed with the signal are blanked. The fader permits a

simultaneous drop in the video feed from one camera, while the video-designated camera is

permitted to rise from black to the standard level.

Figure 4.35 An SEG unit for special effect and production switcher

SPECIAL-EFFECTS GENERATOR

The SEG performs the functions of the switcher-fader and, in addition, provides electronic

gating for special effects. Examples of the SEG's function are side-to-side and top-to-bottom

wipes in which the video output signals from the two cameras share different parts of the

picture area. Comer insertion is achieved by using H and V wipes simultaneously. Various

modulation techniques are employed to achieve such effects as a center insertion of circular or

diamond shapes, or wipe effects that look like a backgammon board. An SEG unit is shown inFigure 4-35.

GENERATOR LOCK

Recent development of large-scale, integrated circuits designed especially for sync generatorapplications has made it possible to build the master sync generator into the camera. Then thecamera can function entirely on its own with internal sync, or it can be switched to make its

internal sync generator follow the H and V sync timing (as well as the color subcarrier signal

phase of any other source of video signals). This method is usually called gen-Iock.

All that is needed to lock the sync generator of a camera so equipped would be a composite

video signal feed from another source~ or a signal composed solely of color burst, blanking,and sync. The latter signal is called a black burst, Figure 4-36 shows a camera setup where


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one camera is used as the master. A composite signal called CVBS ("composite video, burst,

and sync") is obtained from the top camera. This feed is looped through the SEG camera 1

input connectors to the camera control units for the remaining cameras. The lower cameras

are set to lock the sync generators. The upper camera is set to internal sync.

MOTION PICTURES

Television and motion pictures are not compatible formats. Previously it was noted that

television has a 4:3 aspect ratio while movies have a 16:9 aspect ratio. Another major dif-

ference is that television has a frame repetition rate of 30 frames per second, while movies are

repeated at the rate of 24 frames per second. To make a TV format and a film format merge

requires a special projector-camera arrangement called a film-chain-camera. This projector

has to have a mechanical shutter with unequal spacing of the apertures.

Figure 4.36

A multiple-camera hookup, using a gen-Iock. " CVBS" means composite video with burst and

sync.

Motion pictures are also released on videotape with the standard NTSC format and the 4:3

aspect ratio. This difference in horizontal to vertical aspect ratio is apparent at the beginning of

a movie during the opening credits. Also, during familiar scenes, parts of the horizontal

movement are missing on each side of the picture.Some movies are being released in 16:9

format,especially for laserdisc applications.

PORTABLE CAMERAS

Cameras intended for field operations, called ENG (electronic news gathering) or EFP

(electronic field production), have the same basic aspects as the studio camera. However,

unlike the studio version, their emphasis is on portability. A typical setup is shown in Figure 4-

36.


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DIGITAL CAMERAS/CAMCORDERS

Most cameras and camcorders using the CCD image-sensor technology require digital

control and processing circuits, in which everything is being monitored and controlled by one

or more central processors. However, the actual video signal is an analog signal varying in

voltage and frequency. A new generation of cameras and camcorders are emerging. Theseunits will be under a type of digital control in which even the video signal will be in a true digital

binary fonnat. These units will record both the video and the audio onto the tape in digital fonn,

similar to audio CDs or video laserdiscs. The digital system will have a much improved

signal-to-noise ratio. Also today video images can be altered by computers, stored in hard

drives, transferred via modems, printed out as still photos, and edited and manipulated with

complex sophisticated software programs. These cameras/camcorders can either function

as still cameras or perfonn in the traditional color-video fonn. With continued improvements in

video equipment and computers, the lines between the two continue to blur. Future equipment

could operate without tape and may have few moving parts, if any!

SUMMARY

I. Video cameras and camcorders convert light from the scene being viewed into electrical

signals. In the past, different kinds of electron-tube pickup devices were used. Today, a

solid-state device called a CCD (charged-coupled device) pickup is used. The CCD is

small and light, nonnally Y2 in. to 2/3 in. in diagonal measurement. A camcorder is actually

a video camera and a videotape recorder in one compact unit.

2. Many consumer camcorders use a single CCD pickup device. Most of the industrial or

broadcast quality cameras or camcorders use 3 CCDs for higher-quality output signals.

Cameras or camcorders must scan the image point-by-point (or pixel-by-pixel) to produce

an output. Tube pickup devices are scanned like a picture tube; but CCD pickups store a

charge and then it is clocked out of the CCD.

3. The camera signal with blanking and sync is called composite video. The tenns non-

composite video or pre-video are used to identify camera signals without all the other

components of blanking and synchronization. The standard output for composite video is

1 V p-p with negative sync and a 75 ft output impedance; this output matches standard 75

ft coaxial cable.

4. At a television station or production studio, the master control panel (MCP) allows the

control operation to switch from camera to camera and control other functions, and to

communicate with the camera operators.

5. CCD pickups use photodiodes arranged in vertical columns and horizontal rows that store

approximately one-half million pixels of video infonnation. CCD image sensors have many

advantages, including low cost, small size, low power consumption, long life, no lag time,

and no image burn.

6. To find the total number of pixels in a CCD, multiply the number of vertical pixels by the

number of horizontal pixels. Not all pixels are active; some at the top/bottom and sides of

the CCD are for horizontal and vertical blanking. CCDs perform three functions: photo

conversion, charge storage, and charge transfer to the output. Transfer is accomplished

with vertical and horizontal shift registers.

7. Color signals are broken into the three main colors: red, green, and blue. Human vision

peaks in the yellow-green range. The wavelength of light is measured in nanometers.Several methods are used to separate colors. The color filter and the prism are often used.


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8. The luminous signal (Y) is the brighmess signal. The color signal is represented with the

letter C. The color mix of 30% red, 59% green, and 11 % blue results in a proper gray

scale. Mixing these 3 colors results in other colors.

9. Signal processing in the camera or camcorder corrects for white balance, gamma

correction, the addition of sync, black level, and gain control.

10. Optical lenses are required to focus the image onto the pickup device. The focal length

determines the taking angle either for close-up or long shots. The / stop relates to the size

of the iris opening. A lower f number allows more light into the camera.

11. Viewfinders allow the camera/camcorder operator to see what is being televised or

recorded. Some older viewfinders use CRTs; newer units use an LCD display.

12. With microprocessor controllers, many features are incorporated into modern

camcorders. Some of the common features are autofocus, high-speed shutters,

character generators, faders or wipes, macro viewing, on-screen-display, zoom, and

electronic-image stabilization.

13. Camera and camcorder adjustments require some special equipment and should beperformed according to the manufacturer's specifications. The video signal standards can

be given in mVs or IRE units; 140 IRE l!nits are equivalent tol,OOO mVs.

14. Special effects generators (SEGs) allow for production switching and the introduction of

special visual effects. Genlock allows for multiple-camera operation, with precise timing of

the sync and color sub-carrier frequencies. Movie and television formats are not fully

compatible.

15. Most cameras and camcorders use digital control and signal processing, but the video

signal is analog. New units are true digital. New units record digital binary signals onto the

tape. True digital cameras can function as still cameras. Digital video can be processed

through computer systems.


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LIST OF ITEMS THAT COME WITH THE TRAINER

Video Camera Recorder Trainer

The main unit consists of Video Camera Recorder unit, enclosure and fault mechanism

system with block diagram included.Battery Pack

Lithium Battery is source of power to operate the Video Camera Recorder trainer. It is the

original Battery from SONY brand for Video Camera Recorder only.

ChargerIPower supply

The Charger is a power supply unit that is needed for charging battery of Video Camera

Trainer.

Video Camera Recorder User guide.

The User guide is a standard operational of Video camera Recorder from factory

Video Camera Recorder repair Trainer Experiment Manual

This manual consists of job sheets for the student to learn and troubleshoot the Video Camera

Recorder malfunctions.

Including in this manual, are Video Camera Recorder repair Operating Instructions and Service

Manual from the factory. The operating instruction is used to guide the user when using the

Video Camera Recorder and its features. And the last one is a SONY service manual

containing all information needed for servicing the electrical and electronic parts on the Video

Camera Recorder unit.

SETTING UP THE TRAINER

1. Read the manuals that come with the trainer before setting up the Video Camera

Recorder trainer.

2. Unpack the Video Camera Recorder Trainer from its box.

3. The Trainer is designed enough to sit upon a normal laboratory bench when in its

operating condition.

4. Do inventory of all parts according to the list in 3.1.

5. Open the protective cover of Video Camera Recorder trainer.

6. Slide the Battery pack into the battery mounting until it clicks. Check Battery level bypressing the info battery button on the Cabinet R Block, charge the Battery if the power is

low by plugging the charger connector into DC IN port of Video camera trainer.

Note: Use original charger to Video Camera Recorder from SONY.

7. Plug the power cord into the power main.

8. Read the instruction of using fault simulation system before operating the Video Camera

Recorder trainer.

9. Turn ON the Video Camera Recorder.

10. Read the User manual to standard operational of Video Camera Recorder.


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This is the type of knowledge that is very important for any actual field service. The Labtechdesign has taken every step to ensure quality and system safety. In the end, it is up to theperson to ensure no damage is done by incorrect usage

The test points are a mirror of Test Points on the circuitry of the Video Camera Recorder.

These are used to diagnose electrical signals and to compare to OEM (Original EquipmentManufacturer) documentation. The test points are what a student must use in the actual field

servIcmg.

As in any electronic circuit, extreme care must be taken to ensure correct usage. Test Points

cannot be connected each other or used without knowledge of the OEM documentation, and

within the Labtech Experiments.

If incorrectly used, damage can and will occur which could permanently damage the Video

Camera Recorder or the trainer systems, maybe both.

This knowledge, of how to use the Test Points, must be done correctly to get correct results

without damage to the Video Camera Recorder.

THE HARDWARE


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01 - Handycam System

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Transcript of 01 - Handycam System