SEIKO QUARTZ WATCH

DIGITAL TYPE

TECHNICAL MANUAL

CONTENTS

I. SEIKO DIGITAL QUARTZ WATCH ......................................... 1

II. OPERATING PRINCIPLES .......................................... . ..... 2

1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Behavior of liquid crystal, and structural design of liquid crystal panel . . . . . . . . . . . . 2

3. Electronic circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Ill. MULTIPLEX DRIVE ..................................................... 7

1. Difference between multiplex drive and direct drive . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2. Operating principles of multiplex driving system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

IV. SOLAR BATTERY WATCH .. . ............................................. 10

1. Circuit arrangement .................................. . ..... . .......... 10

2. Structure of the panel cover .................................. . ......... 10

V. SPEAKER - OPERATING PRINCIPLES ...................................... 11

1. Alarm circuit ................................... ~ .................... 11

2. Speaker ....................... . .................................... 11

3. Melody alarm .............................. ; ........................ 12

I. SEIKO DIGITAL QUARTZ WATCH

SEIKO DIGITAL QUARTZ WATCH is a highly reliable, all-solid-state liquid crystal display watch. SEIKO's most ad­

vanced technology in high-precision technology and electronics has been incorporated in it as like the analogue quartz watch.

Unlike the analogue quartz watch, SEIKO DIGITAL QUARTZ WATCH has no mechanical elements such as hands and

gear train. All its functions are electronically controlled. The time is displayed on a liquid crystal panel digitally instead of by hands.

Features

• Clear-cut digital display SEIKO DIGITAL QUARTZ WATCH uses a high-quality FE type nematic liquid crystal display which is excellent tn color balance, contrast, and brightness, showing a clear-cut digital display on a wide display panel.

• Solid-state accuracy from quartz crystal oscillation SE I KO DIG IT AL QUARTZ WATCH runs on a quartz crystal oscillator with a stable 32, 768 Hz, showing the high timing accuracy as SEIKO ANALOGUE QUARTZ WATCHES DO.

• High reliability from rationalized structural design All key components such as liquid crystal panel and electronic circuit are manufactured according to SEIKO's most advanced technology and its long experience, and their reliability is exceptionally high.

• Easy-to-maintain The components consist of simplified blocks which facilitate repair service.

• Proof against magnetism SEIKO DIGITAL QUARTZ WATCH has no mechanical moving parts such as magnetic transducers and is insusceptible to. magnetism.

• Diversified functions SEIKO DIGITAL QUARTZ WATCH is available in various models for customer's selection. Depending on the Calibre,

complete calendar function (year, month, date, day of the week), stopwatch function, and other various functions are provided in addition to the time display.

II. OPERATING PRINCIPLES

1. General

(1) The oscillator circuit applies a voltage across a quartz crystal oscillator to keep it oscillating at a stable frequency

of 32,768Hz, and delivers this frequency in the form of an electrical signal. (2) The frequency divider circuit converts this electrical signal sequentially, finally obtaining a train of once-every­

second pulses. (3) The counter, decoder and driver marshal the pulses sent from the frequency divider circuit to generate signals for

driving the liquid crystal display panel. (4) The liquid crystal panel works by the signals from the counter, decoder and driver.

Electronic circuit block Display block

Ouartz crystal oscillator

1----- -- C-MOS-LSI ----------

CD Oscillator circuit 2

Frequency ® devider circuit y 12:5830

® Counter

- • Decoder

Driver

Setting device

I - - - -1- - - - - - - -

I I

I I I

I I

Illuminating light

Regulation system

Upconverter

@-circu-it -~!'------' Battery

Upconverter circuit: A circuit to step up the battery voltage to a leve l necessary for driving the liquid c rystal.

2. Behavior of liquid crystal, and structural design of liquid crystal panel

(1) Liquid crystal As its name suggests, the liquid crystal becomes fluid in a certain temperature range and solid in some other temper­

ature range. It is an organic compound exhibiting intermediate characteristics between liquid and solid crystal, and

optically is organic compound. When stimulated by a change in temperature, electric field intensity, pressure, etc., the stimulated part of the liquid

crystal changes its color or its transparency. Used in the SEIKO DIGITAL QUARTZ WATCH is a high-quality field­

effect (FE) type nematic liquid crystal display whose optical property changes when applied with a voltage. This liquid

crystal display works on a low voltage, consumes current less, and provides a high contrast.

2

•

Three phases of substance

Solid- L iquid , ___ ______ _ Gas

~Liquid crystal~

Ex. Wat er

Ice Water

o·c 1oo·c

(2) Structural design of liquid crystal panel The liquid crystal panel is constructed as ii lustrated below.

VZZZ770//////////////-'4,i-------- Polarization sheet

// _,,_,,__ ________ Upper plate glass

L--1:-:-:-::-:i•.-:-::-l•F-=--W•~*+==~--------T ransparent (segment) electrode. Liquid crystal panel

t_· ·:_·;_:J········L~.:'.:::I+-------------- Liquid crystal ~--....+-----------Transparent (common) electrode !/ // // /I I/ It - Lower plate glass

VZZZZZZZOZZZZZZZ-zi---------Polarization sheet

L,. ___________ ...::i-----------Reflecting mirror

(3) Behavior of liquid crystal and liquid crystal panel

The liquid crystal sandwiched between two glass sheets has its molecules twisted 90° between the top and bot­tom as shown in the illustration on the right. This is accompl ished by applying a special alignment treatment to glass sheets (in which the major axes of molecules are aligned in the arrow-marked direction on the glass surfaces) . Two polarization sheets are also arranged to be staggered by 90° from each other with reference to their polarization axis .

Light waves oscillating in a plane normal to the polarizing axis

Light waves osci.llating in a plane in phase with the polarizing ax is.

Only light waves £:'?j_~~~~f-- oscillating in the

direction of++ are possible.

• No display (no voltage applied )

Of th e light waves incident upon the liquid crystal

panel, those transverse waves which are in phase with the polariz ing ax is are permitted to enter the upper polarization sheet and then into the liquid crysta l. These are turned along the twist of the molecular arrangement on thei r way to the lower polarization

sheet, namely, they are turned by 90° in the ultimate stage.

Arrangement of

liquid crystal

Since the polarizing axis of the lower polarization sheet

is at right angles to that of the upper polarization sheet, the waves thus twisted by 90° can also pass through the lower polarization sheet. After passing it, they reach the reflecting mirror, where they are reflected back passing through the same route. accordingly, the liquid crystal panel appears bright.

Upper molecules (seen

plate glass from the top)

,,,:;__ __ Liquid crystal

Lower plate glass

Polarization sheet

Only light waves oscillating in the direction of t are possible.

3

• When displayed (voltage applied)

When a voltage is applied between a segment electrode

and the common electrode, the resulting electric field

acts to orient the I iquid crystal molecules under its influence vertically.

Thus, admitted waves directly pass through them with­

our twist, and are checked by the lower polarization sheet from reaching the reflecting mirror.

Accordingly, the voltage-on field-affected segment is blacked out.

That is, the segment is displayed in contrast with the surrounding non-affected parts.

In practice, seven transparent segments arranged in an eight figure are shown on the upper plate glass as be­low, and are applied with a voltage selectively to form

any desired numeral pattern.

The parts, a, b, c, d, e, f, and g, shown below are called

the segments. The body formed of some or all of these

seven segments is called the digit.

a

~ f-0 G-b e-fJ9l;- c I

d

3. Electronic circuit

~' u ,- --1 r .. , ___ ..I

I I

~~:::. : I ~-_.,_ - -,

... _ - - - j

~~e r~' I' I I ., I J

-~ ••••••• I' I

I I I I

~) ...

We have just studied how the liquid crystal works 'on- an electric signal. Here we shall take a glance at the electronic

circuits that generate such an electric signal.

The 32,768 Hz signal from the oscillator circuit is divided by the frequency divider circuit and eventually reduced to

a 1 Hz signal. Thus far, the circuit used in the SEIKO DIGITAL QUARTZ WATCH is just the same as that in the

SEIKO ANALOGUE QUARTZ WATCH. In the SEIKO DIGITAL QUARTZ WATCH, the signal from the frequency divider circuit is converted through counter,

decoder and driver into electric signals for displaying numerals.

• Counter The counter is a means to count 1-sec. signals sent from the frequency divider circuit. For example, if sixty pulses of

signal counted make a minute, and the counter counts 1 min. 60 times, it is an hour. In this way, days, weeks and

months are counted.

4

• Decoder The decoder deciphers the counter data into hours,minutes and seconds, and instructs the driver as to what digits of

the liquid crystal panel and what segments of the digits must be designated by supplying current in order to display a

specific number.

• Driver The driver supplies electric signals to each segment at the command of the decoder to drive the liquid crystal molecules.

The electrodes on the liquid crystal panel are supplied with a 32-Hz signal (liquid crystal driving signal) tapped from the

frequency divider. Namely, the common electrodes are supplied with "A" signal while the segment electrodes are supplied with either

.llA" or "B" signal under the control of the driver. (See the illustration below)

Common electrode " A " signal n n n 0 I I I I I I I I I I I

H H I I

Segment electrode "A " signal 0 n

I I I I I I

I I I I I I o r

J I I I I I

"B" signal n n I

Common electrode Segment electrode

A A No voltage between the common and segment

electrodes, and no display.

A voltage is applied between the common and A B segment electrodes and the segment is dis-

played black.

Ex . Driving of e-segment

r~: ~~\ t~' r:t ~ I I I I : ; ____

:l ~~' t\---· 0 ., ' LI I ) I I I I I . ....

~ r - --, .... _ - - ->

0 x 0 x x x 0 x 0 x

(Electric signal one-segment: o .... "B" signal)

x .... "A" signal)

5

• When displaying e-segment ( 1) The decoder gives the driver a command to display

the e-segment. (2) The switch S in the driver is connected to "B"

terminal. (3) The "B" terminal is given "B" signal (an inverted

signal of "A" signal applied to the common elec­trode) and an-E-volt voltage is applied between the common electrode and e-segment electrode, driv­ing the liquid crystal to blacken thee-segment.

When the segment electrode is held at 0 volt, the common electrode will have +E volt and - E volt alternately at a 32-Hz period.

A_B

~ ..._

'--(lJ (lJ > > ·;::::

8 s 0

Inverter

Segment

electrode Y ~~

Counter

w '-- '--(lJ (lJ

.::::. > >

0 ·;:::: ·;:::: 0 0

=!>-------~mon electrode X

32-Hz signal

Common electrode X ("A" signal)

e-segment electrode Y ("B" signal)

• No display of e-segment

("A" signal)

(1) The decoder gives the driver a command not to display thee-segment.

(2) The switch Sin the driver is connected to the "A" terminal.

(3) Since the waveform of the electronic signal at the "A" terminal is the same as on the common electrode ("A" signal), no voltage is applied between the common electrode and e-segment electrode, and thee-segment cannot be displayed, accordingly.

Common electrode X 0 D D X - Y

("A" signal) y 0

e-segment electrode Y 0 D D ("A" signal)

Each segment has a driver of its own, and its display is controlled thereby as explained above.

6

Ill. MULTIPLEX DRIVE

The liquid crystal driving system (driver) explained in the foregoing chapter is called the direct driving system.

In addition to it, t here is another system called the multiplex driving system, which is detailed hereunder.

1. Difference between direct drive and multiplex drive

The following illustration gives a comparison between the multiplex driving system of Cal. M 158A and the direct driving system of Cal. 0634A.

Upper pattern

Lower pattern

Multiplex drive (Ex.: Cal. M158A)

'I I I I i i .,.._

• D3BB•aS:

~q~;BBasE •••

Number of segments: 96

Number of terminals (Number of patterns on both

sides of the liquid crystal panel)

• For segments: 48

• For common electrodes : 2

Total: 50

i Segment electrodes (~ r- (4pcs)

Common electrode 1

Direct drive (Ex.: Cal. 0634A)

AIFfll LAP a 8

1 ria'-a•-• L ijO· o

Number of segments:

Number of terminals:

• For segments :

• For common electrode:

Total:

44

44

45

As illustrated above, in the direct driving system, there is a signal common electrode and a signal segment electrically connected to one segment electrode (patterns on both sides of liquid crystal panel).

In the multiplex driving system which Cal. M158A has adopted, however, the number of common electrodes is in­creased to two, and thereby enabling some segments to be electrically connected with one segment electrode.

Accordingly, the multiplex driving system can display more than twice the number of segments by almost the same number of segment electrodes used in the direct driving system.

7

2. Operating principles of multiplex driving system

Now let us study the operating principles of the multiplex driving system taking Cal. M 158A as an example.

Taking the segment "a" and "b" al?ne, we find the following four combinations of "LIGHTING (ON)" and "NOT LIGHTING (OFF)".

Combination Segment "a" Segment "b" (Segment (corresponding (corresponding

signal) to common to common electrode 1) electrode 2)

A ON ON B OFF OFF c OFF ON D ON OFF

Terminal (One of the patterns located on both sides of the liquid crystal panel)

The ON and OFF conditions shown in the above table are determined by how the signals of the common electrodes 1 and 2 and the signals A, B, C and D are combined.

Common electrode

Terminals to two segments

0

{

Common electrode 1

Common electrode 2 o __, ___ _

I

I I I

E/2 E

0 :----i.__~~--L------l~~....____.L_ __ __.....___,;~--__!_E Signal A *(1 ON, 2 ON)

Signal B (1 OFF, 2 OFF)

Signal C (1 OFF, 2 ON)

Signal D (1ON,2 OFF)

+E = 1.58V E ='7 3.lV

I I I

r: o~1--~L_ __ __. __ __;,~--'-__:_---'~-...:.~--1.~-__:

I

Battery voltage

Up-converted voltage

* (1 ON, 2 ON) denotes that the segments corresponding to the common electrodes 1 and 2 are lighting. "OFF" indicates that the segment is not lighting.

8

When the signal D is applied to the terminals of the segments "a" and "b", the following states will be established.

Signal of common electrode 1

Signal D

Common electrode 1 and segment "a"

0 I I

0 J

+ E

+ E/ 2 I

0 I

- E/ 2 I

- E

I I I I

I :

Segment "a" is lighting

Signal of common electrode 2

Signal D

Common electrode 2 and segment "b"

I

0 J I I

0 J

+E/2 I

0 : - E/ 2 I

l ! ! l I I I I I I

I I

I ! ! I I

I : I

I

I I

CJ

Segment "b" is not lighting.

9

IV. SOLAR BATTERY WATCH

1. Circuit arrangement

,1/ -0-/ 1' -8-, -,,,,,,

Solar battery

Recharge control circuit

Electronic .__ __ , suM;TuWETH FR SA~ circuit ~--1 In .• -•• -•. - .-,

'-------..----' L• • L• C• =· =·

Diode

(1) The solar battery changes light energy as from sun and incandescent lamp etc. into electric energy. Its output is sent to the movement after passing through the recharge control circuit and secondary battery.

(2) The recharge control circuit always monitors the terminal voltage of the secondary battery; when the secondary battery runs short of energy, the recharge control circuit functions to supply current from the solar battery to the secondary battery. When the secondary battery is topped up, the control circuit cuts off current supply.

(3) Like the regular silver oxide battery, the secondary battery shows a flat discharge voltage . (4) The diode functions to check the backflow of current from the secondary battery to the recharge control circuit.

2. Structure of the panel cover

The following is an explanation of the panel cover with reference to Cal. A 156A. ( 1) In the case of Cal. A 156A, the solar battery is

mounted under the panel cover. (2) As illustrated on the right, *SB unit is attached to

the panel cover. (3 ) The SB unit has silicon solar cells adhered on it. (4) Electric energy generated in the solar cells passes

through cell electrodes to the copper foi l pattern of the SB unit and then into the module.

* SB short for Solar Battery.

10

I EB Electrode

Copper foil pattern

V. SPEAKER - OPERATING PRINCIPLES

1. Alarm circuit

The alarm circu it consists of an alarm time memory circuit, alarm coincidence circuit, alarm control circu it and a speaker drive ci rcuit.

r------- ---- -1 I

I

I

I I

Oscillator circuit Frequency

divider circuit

Time counter circuit

Alarm time memory circuit

4096Hz Alarm signal 1----.· __Jffi_Jlfl__Jl forming circuit

Decoder

D ri ver

Alarm coincidence f---~ circuit

Alarm control circuit I

Liquid crystal panel

Speaker drive

'circuit

I l__Jffi_JJjl___J

110

[_ - - - _J

C-MOS-LSI

(1) The alarm time memory circuit keeps in memory a given alarm set time. (2) The alarm coinc idence circuit compares the data in the time counter circuit with that of the alarm time memory

circuit, and signals when the data coincidence is noticed. (3) The alarm signal forming circuit converts the output signal of the frequency divider into the one fitted for the

alarm.

(4) The alarm control ci rcuit makes a decision according to the output of the alarm coincidence circuit as to whether the speaker should be dr.iven or not. The alarm control circuit also functions to stop the alarm.

(5) The speaker drive circuit amplifies the output of the alarm control circuit to drive the speaker.

2. Speaker

Diaphragm Armatu re Dust protective sheet Speaker cover

Speaker gasket

Caseback gasket

Speaker coil Caseback Core Permanent magnet

Note : The ill ustration above refers to Cal. A 159A.

11

(1) c:MOS-LSI supplies a 4,096 Hz signal to the speaker coil. (2) The speaker coil generates an alternating magnetic field of 4,096 Hz. (3) The core at the center of the speaker block is magnetized to vibrate the armature at a frequency of 4,096 Hz. (4) Since the armature and diaphragm are integrated, the diaphragm also vibrates at the same frequency, emitting a

sound.

The resonant frequency of the speaker is 4,096 Hz, the same frequency as the drive signal. For th is reason, the speaker can deliver an enough loudness for all that its current consumption is extremely low. The signal sent from C-MOS-LSI to the speaker has the waveform shown below.

,____ ~

I{~ sec l/Bsec _,_ ~ 1

I ~ . "' "' ., 1/Bsec 1 sec

~

r ..

3. Melody alarm

The melody alarm is different from the conventional alarm in the following points.

r------- - - - -----1 r------------------

Oscillator circuit

Frequency divider circuit 1---:.___~ Tempo circuit

Memory for rhythm circuit

Memory control circuit

Memory for melody circuit

...___ .___

- - -,

L------------- - - --- ------.l

I

Time counter circuit

Alarm time memory circuit

'---------- - -

12

Decoder Driver

- I

Alarm coincidence Alarm control f--------------1----~ circuit circuit

Liquid crystal panel

Su J;; Tu WE TH Ftl SA [JJ

10:08 59

Speaker drive circuit

CD The melody alarm uses a tempo circuit, rhythm circuit, melody circuit and control circuit. (In the conventional alarm, an alarm signal forming circuit is used.)

® The tempo circuit determines the standard length of a musical note with the clock signal as a basis. @ The rhythm circuit determines the lengths of the derivative notes according to the standard note determined in

the tempo circuit. @ Melody circu it tones the notes determined in the rhythm circuit. @ For the purpose of playing a music, notes and pauses are memorized sequentially in the control circuit. The notes

and pauses are subjected to tempo, rhythm and melody cor:itrol operations while being played back according to the memory.

@ The melodious signal thus formed is sent to the speaker drive circuit where it is amplified to sound the speaker. (j) The melody alarm uses a wide-band microspeaker whose diaphragm is specially designed to play a clear, sweet

melody with fullness of volume.

Determines a tempo

Determines a rhythm

Determines a melody

J 60

I I I I I

262Hz : 330: 392Hz I Hz 1

13

K. HATTORI & CO., LTD., TOKYO, JAPAN 80-7 Printed in Japan