Table of Contents - · PDF file7.2 Custom Design Parameters ... 11.0 Product Specifications...

Table of Contents

1.0 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3.0 How the High Precision MicroJoystick™ Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

4.0 Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

5.0 Technology Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

6.0 Component Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

7.0 Mechanical Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7.1 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7.2 Custom Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

7.3 Tail Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

7.4 Cap Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

8.0 Electronic Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9.0 Software Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

10.0 DO’s and DON’Ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

11.0 Product Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

12.0 PC-Interface Circuit Components List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

13.0 Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Version 0.2 ©1997 Interlink Electronics, Inc.Publication Number: 90-45488 Rev. D

VersaPoint is a registered trademark of Interlink Electronics, Inc. MicroModule is a trademark of Interlink Electronics, Inc. IBM, OS/2 and PS/2 are registered trademarks of International Business Machines, Corp. Windows, Windows 95, 98 and MS-DOS are trademarks of Microsoft Corporation.

All other trademarks are the property of their respective owners.

1.0 ScopeThis Design Guide is intended to provide OEMs with a comprehensive overview on evaluating and inte-grating Interlink Electronics’ High-Precision MicroJoystick™. If questions arise that are beyond the scopeof this design guide, please contact Interlink Electronics Product Support. Contact information forInterlink Electronics Product Support can be found in Section 13.0. Before using or installing the High-Precision MicroJoystick, please take a few minutes to carefully review this Evaluation Guide.

2.0 Functional DescriptionThe High-Precision MicroJoystick is an innovative, intuitive, OEM pointing system that delivers simultaneous360o control of direction and speed at the touch of a fingertip – ideal for integration into notebook computers,remote controls, games, ruggedized products, and other portable products where space is limited. The High-Precision MicroJoystick is based on Interlink Electronics’ patented pressure-sensitive Force Sensing Resistor®

(FSR®) technology. The dynamic response of FSR technology enables the lightest of touches to be translatedinto smooth, intuitive cursor control, while simultaneously enabling dynamic speed control by altering theamount of applied pressure.

High Precision MicroJoystick Interlink Electronics, Inc. • Page 1

3.0 How the High-PrecisionMicroJoystick™ WorksWhen you place your finger on the top of the High-Precision MicroJoystick, the pressure exerted byyour finger is transmitted to the 4-zone VersaPoint® FSR sensor located in the joystick’s base. The4-zone VersaPoint sensor consists of four overlapping zones designed to produce smooth, light cursorresponse. The force distribution over the four zones is immediately converted by the microcontrollerinto cursor movement in the direction of applied force. The micro-controller’s dedicated firmwareoptimizes the cursor’s speed response and accuracy; the result is smooth cursor movement in anydirection, from a precise crawl to a screen-crossing zip.

4.0 Features and BenefitsThe High-Precision MicroJoystick has many features and benefits that make it a versatile pointing solu-tion for a variety of applications.

RUBBER CAP

ACTUATINGSTICK

HIGH-PRECISIONMICROJOYSTICK

BASE

4-ZONE FSR SENSOR (IN MICROJOYSTICK BASE)

HIGH-PRECISION MICROJOYSTICK TAIL(CONNECTS TO MICROCONTROLLER)

Page 2 • Interlink Electronics, Inc. High Precision

Unparalleled Noise and ESD Properties The High-Precision MicroJoysticks low-gain electrical circuitry is inherently resistant to electrical noise and electro static discharge (ESD). In addition, the High-Precision MicroJoystick’ssimple, no-moving-parts design makes it highly resistant to vibration and mechanical noise.

Low Power UsageThe High-Precision MicroJoystick is compatible with 3.3 and 5.0 volt systems. Using less power thanstrain-gauge joysticks, the High-Precision MicroJoystick allows integrators to extend battery life – acrucial element of mobile system design. Typical operating consumption at 5V is less than 5 mA; andat rest, less than 3 mA. Typical operating consumption at 3.3V is less than 2.5 mA; and at rest, lessthan 1.5 mA.

Unsurpassed Quality and ReliabilityInterlink Electronics employs a fully-automated robotics assembly line to assemble and test each High-Precision MicroJoystick. After assembly, every joystick is 100% tested for “feel”, responsiveness,smoothness of cursor control, and directional symmetry – ensuring superior levels of part-to-part consistency and performance. The High-Precision MicroJoystick reliability is a benefit of its no-moving-parts design – making it virtually maintenance free and highly resistant to contamination. High-PrecisionMicroJoystick pointing solutions are rated to lifetimes in excess of five million cycles.

Simple Electronics and Low Part CountThe High-Precision MicroJoystick uses Interlink Electronics’ patented VersaPoint™ technology.Reliability, durability and simplicity are intrinsic to VersaPoint technology. Utilizing a simple timingcircuit, the High-Precision MicroJoystick is uncomplicated and easy to integrate. With less than half thenumber of components of other joystick technologies, a minimum of board space is required for integration.

Compact Design Facilities Integration FlexibilityThe compact size of the High-Precision MicroJoystick allows it to be mounted in-between keys onkeyboards – close to the user’s hands – below the space bar, into front panels, or virtually anywhere!The compact size – much smaller than Trackballs or Touchpads – allows it to be easily integrated intotight, cramped spaces and frees up space for other system components. The High-PrecisionMicroJoystick is unaffected by mounting orientation, whether horizontal, vertical, or any angle in-between, providing integrators maximum flexibility with product design.


Robust Environmental PropertiesThe High-Precision MicroJoystick’s robust environmental properties make it the ideal pointing devicefor use in almost any environment – from climate controlled cleanrooms to hot and humid tropical climates. Operation of the High-Precision MicroJoystick is completely silent … for applications whereperfect silence is mandatory.

Unrivaled Hardware and Operating System SupportStandard High-Precision MicroJoysticks support PS/2® and Microsoft® serial two-button mouse hard-ware interfaces and DOS, Windows 3.x, Windows 95, 98, 2000 and OS/2 operating systems (since thePS/2 interface is a standard, the High-Precision MicroJoystick is compatible with any operating systemvia the PS/2 interface). For enhanced operation in Windows or DOS, a VersaPoint Windows or DOSmouse driver is available that improves performance and adds many adjustment features. Custom electrical interfaces and microchips can be developed to support other hardware interfaces and operatingsystems, e.g., Apple Desktop Bus (ADB) Macintosh, NEC98, etc.

Easily CustomizableStandard High-Precision MicroJoystick systems consist of a pointing stick and a micro-controller withdedicated firmware. The size and shape of the joystick’s base can easily be customized to meet varioussize requirements. Custom, turnkey module solutions (e.g., a trackball-replacement module) are alsoavailable. For more information on custom solutions, contact Interlink Electronics Product Support.


5.0 Technology ComparisonThe High-Precision MicroJoystick offers many features unrivaled by strain-gauge joysticks. The tablebelow compares the features of the High-Precision MicroJoystick and strain-gauge joysticks.

Property High-Precision MicroJoystick Strain-Gauge Joysticks

Overall Cost Low Twice as costly

Durability HighModerate

Ease of Integration HighModerate

Basic cursor tracking Smooth, Light, Sensitive Smooth, Light, Sensitive

Useable at 3.3 volts Possible Impossible

ESD Susceptibility Extremely Low Very High

Power Consumption Low Higher

Pad and electronics cost Low Higher

Number of components 16 35

Board-space area Low Higher

6.0 Component DescriptionPackagingThe standard High-Precision MicroJoystick system is a component-level solution consisting of a joy-stick, a microcontroller, and a rubber cap. The integrator provides the interconnect cable, and a few simple electronic components (to support the microcontroller). Customized, turnkey modules can bedesigned that simplify integration and improve time-to-production. Custom interconnect cables,designed to connect the joystick or module to system boards, can also be supplied by InterlinkElectronics.


High-Precision MicroJoystick CapsTypical caps which Interlink Electronics supplies are made of rubber and are designed to slip over the top ofthe High-Precision MicroJoystick’s actuating stick. Interlink Electronics can help you differentiate your productin the marketplace, by supplying rubber caps in a variety of custom colors or by designing custom caps.Custom, molded hard-plastic caps can be designed to produce a “control-disk” or “control-sphere” interface.Since the design of the cap can influence the cursor response, please contact Interlink Electronics beforedesigning and/or integrating a custom cap.

Hardware Interface SupportThe standard High-Precision MicroJoystick utilizes a PS/2 hardware interface. Other hardware interfaces –serial (RS232), Apple Desktop Bus (ADB), NEC98, etc. – can be supported with custom electronic interfaces. When the Universal Serial Bus (USB) specifications committee finalizes itsspecifications, Interlink Electronics plans to support the USB interface as well.

Driver SoftwareAny Microsoft driver will operate the High-Precision MicroJoystick. Drivers for other operating systems,e.g. Windows NT 2000 utilizing the standard drivers, OS/2, Macintosh, etc., will also operate the High-Precision MicroJoystick. Interlink Electronics’ VersaPoint software driver provides additional features, suchas speed, acceleration, pointer adjustments, and click & drag lock. The VersaPoint software runs on DOS,Windows 3.x and Windows95 operating systems. To support the High Precision MicroJoystick’s uniqueClickStick feature, ClickStick drivers can be supplied to meet individual customer requirements.

Exposure to LiquidsThe self-contained design of the High-Precision MicroJoystick makes it highly resistant to contamination andfailure caused by dust or liquids. In general, the High-Precision MicroJoystick is better protected than thekeyboard or system into which it is integrated. However, the High-Precision MicroJoystick is NOT sealedagainst liquids. Exposure to moisture could affect the flex-circuit connection juncture. There is a small vent atthe base of the stick, opposite the connection juncture; the joystick’s operation may be impaired if moistureenters this vent. If your application requires complete immunity to water, please contact Interlink ElectronicsProduct Support and request information on DuraPoint OEM Module, “The World’s Toughest Mouse.”

Standard Cap Control Disk Cap Control Sphere Cap


7.0 Mechanical Integration 7.1 Mounting the High-Precision MicroJoystickThere are a variety of mounting methods available to the integrator. The High-Precision MicroJoystickmay be mounted on the frame of a keyboard, either by mounting it directly on top of the frame or bymounting it from underneath the frame with the stick protruding through the frame. Its compact size eas-ily fits within the constraints of most notebook keyboards. In addition, the High-Precision MicroJoystickcan be mounted on a case or bezel, or directly to a printed-circuit board. Figure 1 on the next pageshows the dimensions of the High Precision MicroJoystick assembly.

How to Adhere to Printed Circuit BoardNever solder directly to the connecting traces on the printed circuit board of the High-PrecisionMicroJoystick; the material used for the conductive pattern is not solderable. Instead use standard orcustom flex circuit attached using heat-bonded anisotropic conductive adhesives or pressure-sensitiveanisotropic adhesives. However, in order to ensure that the pressure-sensitive adhesive joint is robustand reliable, a compressive force must be applied to the adhesive joint. A molded-in rib or mechanicalclamp can be used to supply the compressive force.

Mounting MethodsSeveral different mounting methods are detailed in the following section. Before designing a mountingmethod for the High Precision MicroJoystick, please carefully review all of the suggested mountingmethods and design parameters. This will enable you to design the best mounting method for your sys-tem, reduce time to production, and help optimize your installation procedure.


Figure 1High Precision MicroModule, 7.4 mm Assembly


7.1.1 Mounting Method 1: A molded-in detail

A simple molded-in detail can be used to mount the High Precision MicroJoystick. This method is idealfor integration of the High Precision MicroJoystick in-between keyboard key caps (i.e., the detail can bemolded directly into the keyboard’s “eggcrate” base, eliminating or reducing incremental system costs).Either pins or a close-tolerance fit around the High Precision MicroJoystick’s captuator can be used toregister the High Precision MicroJoystick in the detail as shown in the illustrations below.

Registering with Pin Registering by the Captuator

The portion of the molded-in detail that holds the High Precision MicroJoystick’s base is designed to beslightly thicker than the thickness of the High Precision MicroJoystick’s base. This helps preventunwanted forces from being applied to the High Precision MicroJoystick. Since the High PrecisionMicroJoystick is designed for maximum sensitivity, forces as small as 20 grams can cause cursor move-ment or cursor “drift.” The term, “drift,” is used to describe cursor movement caused by unwanted forcepermanently applied to the FSR in the mounting process.A support plate is used to keep the High Precision MicroJoystick in place. The support plate should beflat and free from surface defects (e.g., bumps). The support plate can be the backplate of a keyboard orcan be constructed as a separate metal or plastic unit.To install the High Precision MicroJoystick, simply drop the High Precision MicroJoystick into thedetail, register the High Precision MicroJoystick around the captuator or on the pins, check to make surethe High Precision MicroJoystick is positioned correctly, and install the support plate. Please see Figure2, “Using Pin in Top Plate for Registration with Support Bosses at Bottom.”

MOLDED-IN DETAILOR EGGCRATE BASE

REGISTRATION PINS

ACTUATOR(WITHOUT CAP)

CAPTUATOR

MJ BASE

SUPPORT PLATE

CLOSE TOLERANCE FITAROUND CAPTUATOR

LEAVE ENOUGH MARGINFOR ACTUATOR MOVEMENT

CAPTUATOR


Figure 2Using Pin in Top Plate for Registration with Support Bosses at Bottom


7.1.2 Mounting Method 2:A low profile molded-in detail and special support plate

If the depth of the detail in section 7.1.1 is too great, a low-profile detail can be used in conjunctionwith a special support plate to mount the High Precision MicroJoystick as shown in the illustrationbelow. As in section 7.1.1, either a close-tolerance fit around the High Precision MicroJoysticks captua-tor or pins can be used to register the High Precision MicroJoystick in the detail. The sketch below illus-trates pins being used to register the High Precision MicroJoystick in the low-profile detail.

The support plate has an indentation in it to capture the High Precision MicroJoystick’s base. The thick-ness of the indentation is slightly thicker than the thickness of the High Precision MicroJoystick’s base.This prevents unwanted forces from being applied to the High Precision MicroJoystick that could causeunwanted cursor drift. The support plate should be flat and free from surface defects (e.g., bumps), andcan be integrated into the backplate of a keyboard or can be constructed as a separate metal or plasticunit.To install, drop the High Precision MicroJoystick into the detail, locate the High PrecisionMicroJoystick on the registration pins, check to make sure the High Precision MicroJoystick is posi-tioned correctly, and install the support plate.Please see Figure 3, “Using Self Tapping Screw with Indented Support Metal Plate.”

ACTUATORPINS

BASE

SUPPORT PLATE INDENTATION

SUPPORT PLATE


Figure 3Using Self Tapping Screw with Indented Support Metal Plate


7.1.3 Mounting Method 3:Mounting the High Precision MicroJoystick to a flat surface

The illustration below shows how the High Precision MicroJoystick can be mounted to a flat surfacesuch as a PCB or molded keyboard housing.

The holes in the mounting surface should be designed as clearance holes (e.g., larger than the threaddiameter of the screws). This helps to ensure that the screws only thread into one surface -- the HighPrecision MicroJoystick’s base. If the screws thread into both the High Precision MicroJoystick’s baseand the mounting surface, the resultant stress could cause cursor drift.Alternatively, the screws can be installed from the top of the High Precision MicroJoystick as shown inthe illustration below.

Wheninstalling

screws from the top of the High Precision MicroJoystick, the holes in the High Precision MicroJoysticksbase are clearance holes. The screws should only thread into the mounting surface. If the holes in theHigh Precision MicroJoystick are too small, they may be drilled out and enlarged.

7.3 Tail Attachment

The High Precision MicroJoystick is designed for easy attachment of flexible-circuit tails. Interlink

INSTALLING SCREWS FROM BOTTOM

LARGER OPENING IN MOUNTINGSURFACE THAN IN BASE

BASE

MOUNTING SURFACE

INSTALLING SCREWS FROM TOP

LARGER OPENING IN BASE THANIN MOUNTING SURFACE

BASE

MOUNTING SURFACE


The mounting surface must be flat to within 0.0005”. Bowing of the mounting surface or surface bumps can cause preloads on the High Precision MicroJoystick resulting in unwanted cursormovement. To help reduce the effects that any existent bumps or bowing may have, a hole or indentation0.50” to 0.60” in diameter can be machined or molded into the mounting surface as shown below.

The hole/indenta-tion should be centered on the High Precision MicroJoystick’s stick. Alternatively, a spacer can bedesigned with a hole/indentation and mounted in-between the High Precision MicroJoystick and themounting surface. For more information on this mounting method, please refer to the Figure 4, “UsingCaptuator for Registration with Opened Support Plate.”To install the High Precision MicroJoystick, inspect the mounting surface, High Precision MicroJoystickand optional spacer to ensure that they are clean and free of contaminants (e.g., dirt, dust, hair, etc.).Then place the optional spacer on the mounting surface, and place the High Precision MicroJoystick onthe mounting surface/spacer and install the screws. Use care to torque the screws evenly and ensure thatthey only thread into one surface (i.e., either the High Precision MicroJoystick’s base or the mounting surface, depending onwhether installing the screws from the bottom or top).

Note: When mounting the High Precision MicroJoystick to a flat surface, please carefully review the ESD concerns described in section 7.2.

HOLE/INDENTATION IN MOUNTING SURFACE

BASE

MOUNTING SURFACE


Figure 4Using Captuator for Registration with Opened Support Plate


7.1.3 Mounting Method 4: Adhesive

One of the simplest ways of mounting a High Precision MicroJoystick to a flat surface is to use a pressure sensitive adhesive. Companies such as 3M Corporation make such adhesives, and can recommend a specific product. Generally, the adhesive bond becomes stronger overtime, reaching its maximum in about two days. If you will need to use the holes for screws to registerthe High-Precision MicroJoystick (in addition to the adhesive), then you may need to cut out the adhe-sive strip where it overlays the holes.

7.1.4 Mounting Method 5: Heat-stake pins

Heat-stake pins may also be used to mount the High Precision MicroJoystick to a flat surface. A horn can be designed to melt plastic into the three holes to secure the base into place.


7.2 Custom Design Parameters

Interlink Electronics strongly recommends using one of the mounting methods described in section 7.1. However, these methods may not be appropriate for all systems. If you do need to designan alternative mounting method, please review the design parameters given below.

Note: These design parameters are not an all-inclusive list. Sound engineering practicesshould be used when designing any mounting method. Before proceeding to production, any mounting method should be carefully reviewed and tested to ensure that it does not impair the performance of the High Precision MicroJoystick(e.g., introduce bias, cause preloads on the High Precision MicroJoystick, etc.) orintroduce other unwanted effects.

Flatness of the Mounting Surface -- If the High Precision MicroJoystick is mounted to a flat surface,the surface should be flat within 0.0005”. As detailed in section 7.1.3, a hole or indentation in themounting surface can help reduce the unwanted effects of the mounting surface on the High PrecisionMicroJoystick.Screwing into Two Surfaces – Do NOT screw into two surfaces. If screws are used to mount theHigh Precision MicroJoystick, the screws should only thread into one surface. For example, if the HighPrecision MicroJoystick is mounted to a mounting surface, the mounting screws should only thread intothe mounting surface and not the High Precision MicroJoystick’s base. Threading into two surfaces (i.e.,the High Precision MicroJoystick’s base and the mounting surface) can cause unwanted forces to beapplied to the High Precision MicroJoystick. These forces could cause cursor movement or cursor drift.Please refer to section 7.1.3.ESD -- When designing a mounting system, care should be taken to consider your electro static dis-charge (ESD) requirements. The exposed connecting traces should be properly insulated against anydirect source of static electricity. Your mounting system should be designed with a large enough dielec-tric strength (i.e., length of air path from the ESD probe to the conductive traces on the High PrecisionMicroJoystick’s base plus any additional dielectric insulation) to prevent unwanted ESD effects. Generally, the further you can burythe High-Precision MicroJoystick into the mounting surface, the better your protection against ESD.Whenever possible, the mounting methods in Section 7.1 have been designed with long or lengthenedair paths from the ESD probe to the High Precision MicroJoystick’s conductive traces. Testing is basedon IEC 801-2 requirements using only the air discharge method. The High-Precision MicroJoystickwith “captuator hidden” mounting method was subjected to 5, 10 and 15 KV electrostatic discharges.Since the High-Precision MicroJoystick ESD housing material, mechanical design and Flex PrintedCircuit attachment will be performed by the integrator, ESD testing should be repeated after the actualintegration. Actual ESD tolerance or resistance is subject to the integration design. Please see Figure 5,“MicroJoystick ESD Test Information.”


Registering the High Precision MicroJoystick by its Edge – Registering by its edge is probablythe most difficult means of registering the High-Precision MicroJoystick. If the High PrecisionMicroJoystick is registered by the edge of its base, please note that the positional tolerance from theedge of the High Precision MicroJoystick’s base to the center of the stick is .012” to .015”. Therefore,mounting by the edges of the base can cause the position of the stick to move by that amount. If thatvariance is too great for your system, you should use the mounting holes or a close-tolerance fit aroundthe captuator for registration purposes. The tolerance from the mounting holes to the stick is 0.007” andthe tolerance from the captuator to the stick is 0.008”.Additional Mounting Assistance -- If questions or issues arise when designing a mounting method,please feel free to contact Interlink Electronics Product Support.

Figure 5MicroJoystick ESD Test Information


Electronics can supply flexible-circuit tails designed for use with the High Precision MicroJoysticks orcan supply High Precision MicroJoysticks with tails attached. Electrical connections between the HighPrecision MicroJoystick and a flexible-circuit tail are typically made using conductive adhesives. Beforedesigning an attachment method for the High Precision MicroJoystick’s tail, please carefully review thissection.

7.3.1 Flexible-Circuit Tails

Interlink Electronics can supply custom-designed flexible-circuit tails in a variety of materials (e.g.,polyester, polyimide, etc.). If you wish to fabricate your own tail, Figure 6, “Flex Tail” illustrates a stan-dard flexible-circuit tail used by Interlink Electronics.

Figure 6Flex Tail


7.3.2 Anisotropic (Z-axis) Conductive Adhesives

Electrical connections between the High Precision MicroJoystick and a flexible tail are typically madewith a Z-axis conductive adhesive. These adhesives offer excellent Z-axis conductivity, with little leak-age in the X and Y axis. Two common types of Z-axis adhesives are heat-bond adhesives and pressure-sensitive tape adhesives. Please review the following sections that detail design parameters for bothstyles of Z-axis adhesives, so you can select the best adhesive for your application.

7.3.2.1 Heat-Bond Z-axis Adhesives

Flexible-circuit tails can be attached to the High Precision MicroJoystick with heat-bond Z-axis adhesives. For a list of recommended heat-bond adhesives or if you would like to source the tailattachment, please contact Interlink Electronics. Interlink Electronics can attach tails using heat-bondadhesives, or recommend vendors who can attach tails with heat-bond adhesives.Heat-bond adhesives are activated by heat and pressure. A heated ram applies the heat and pressure to the bond joint allowing the adhesive to attach to the polyester tail and the High PrecisionMicroJoystick. Special care should be taken to ensure that the ram head is parallel to the bond joint. Ifthe ram is not parallel, open circuits or biases (caused by high-resistance connections) could result. Formore details on applying heat-bond adhesives, please contact your adhesive or heat-bonding machinevendor.

High temperatures used in the heat-bonding process ensure that the dwell time is short enough that theconductive traces on the High Precision MicroJoystick are not damaged. At high temperatures and pres-

sures, the conductive traces on the High Precision MicroJoystick “flows” and can cause open circuits orshorts.

RAM

ADHESIVECONDUCTIVE TRACES

TAIL

PROPERLY ALIGNED RAM MIS- ALIGNED RAM


7.3.2.2 Pressure-Sensitive Z-axis Adhesives

Z-axis conductive adhesive offers an inexpensive and, if used correctly, a reliable means of connectingFSRs to flexible circuit tails. The Z-axis adhesive used by Interlink Electronics is 0.002” thick and ismanufactured by 3M Corporation (Scotch™ brand number 9703). When handling the sensor, careshould be taken to prevent touching and to prevent wrinkling of the adhesive. This can lead to a short,leakage in the X and Y directions, or an open circuit. Since the Z-axis adhesive does not provide a strong mechanical bond, a compressive force to the connection joint should be devised. Applying pressure to the connection joint will prevent delaminationof the adhesive which can lead to an open circuit. For example, a rib could be designed into the assembly to apply pressure to the joint. Rubber could be used on the end of the ribto take up tolerances in the design.

Using a Rib to Compress the Adhesive Joint

The compressive force on the joint should be applied within a few minutes of assembling the FSR to theflexible tail. This will help prevent the Z-axis adhesive from delaminating and being exposed to contam-inants. If the Z-axis tape is exposed to contaminants, the electrical conductivity of the tape can be permanently impaired even with the application of pressure to the bond joint.3M Corporation also makes a primer for their adhesive tapes that helps increase the mechanical strengthof the adhesive. Wipe it on; then apply the adhesive and tail. 3M recommends “3M Tape Primer 94” for use with its Z-axis adhesive tapes.

FLEXIBLE TAIL

CLAMPFORCE

Z-AXIS ADHESIVE

RUBBER

RIB

RIB

RUBBER

FSR


7.3.2.3 Attaching a Flexible-Circuit Tail to the High-Precision MicroJoystick

When attaching the flexible-circuit tail to the High Precision MicroJoystick’s conductive traces, careshould be taken to ensure that the tail is properly aligned to the conductive traces on the High PrecisionMicroJoystick’s base. The sketch below illustrates a properly aligned tail and an improperly aligned tail.

When handling conduc-tive adhesives, use care to avoid wrinkling the tape which could cause leakage in the X or Y directionsor open circuits. The adhesives should not be touched with bare fingers, and the conductive traces of theHigh Precision MicroJoystick should be clean (i.e., free from dirt, dust, oil or other contaminates).Contaminants on the adhesive or High Precision MicroJoystick can impair electrical conductivitybetween the High Precision MicroJoystick and the flexible circuit. If the conductive traces of the HighPrecision MicroJoystick need to be cleaned, use a soft material (e.g., a cotton swab) moistened with isopropyl alcohol. The cotton swab should only be moistened with alcohol, not dripping.This will help prevent the alcohol from wicking into the captuator base. Use care not to scratch the con-ductive traces when cleaning the High Precision MicroJoystick.

Peel forces applied to the bond joint can cause the adhesive to delaminate. If peel forces are likely to beapplied to the joint, a method of mechanically reinforcing the joint should be devised (as recommendedin section 7.3.2.2, a mechanical reinforcement should always be used with pressure-sensitive Z-axisadhesives). For example, if a long tail is attached to the High Precision MicroJoystick, the alignment ofthe tail may not be perfect. If a mis-aligned tail is bent when placed into a connector, peel forces couldbe transferred to the bond joint. To prevent delamination of the adhesive, a mechanical compressiveforce should be applied to the bond joint. The sketch on the next page details this situation.

12.0 PC-Interface Circuit Components List

12.0 PC-Interface Circuit Components List

MICROJOYSTICK

FLEX-TAIL

PROPERLY ALIGNED TAIL MIS-ALIGNED TAIL


7.3.3 Handling of High Precision MicroJoystick

High Precision MicroJoysticks are typically shipped in plastic trays that are designed with individualizedcompartments for each High Precision MicroJoystick. Since the trays are designed to protect each HighPrecision MicroJoystick from damage (the base of the High Precision MicroJoystick is hard enough toscratch the conductive traces), please try to incorporate these trays into your inventory and manufactur-ing process. When installing tails or handling the High Precision MicroJoysticks, keep each unit separatefrom each other to help prevent damage to the conductive traces.If the High Precision MicroJoystick is stored for a prolonged period of time before installation of a tail,the conductive traces on the base of the High Precision MicroJoystick may oxidize. This is a normalcondition and does not affect the performance of the High Precision MicroJoystick or the reliability ofthe electrical connection.

MICROJOYSTICK

TAIL

CONNECTION HEADERFOR TAIL

PROPERLY ALIGNED TAIL MIS-ALIGNED TAIL(REQUIRES TAIL TO BE BENT SLIGHTLY

TO FIT INTO CONNECTION HEADER)


7.4 Cap Designs

The High Precision MicroJoystick has been designed to accept a wide range of caps. The cap material istypically made of a soft rubber, but hard plastic (similar to a key cap) also works well. Several standardcolors of rubber caps are available from Interlink Electronics, and custom caps can be manufactured toyour color specifications. You may wish to include several different caps of different colors to your cus-tomer. This allows them to choose a color to match their preferences and ensures that they have extrareplacement caps.In addition to rubber caps, Interlink Electronics can supply hard-plastic caps with the High PrecisionMicroJoystick. Several different designs are available as a standard or Interlink Electronics can build acustom hard cap to your specifications. Hard-plastic caps can be molded with a divot designed to fit afinger tip, a dome for a “track-ball” like shape, or a custom shape to fit your application.

For spe-cialty applications, you may wish to integrate the cap into your sealing mechanism (e.g., mold a capwith a rubber flange that can be sealed into your system). If the High Precision MicroJoystick is sealedinto a system, take special care to ensure that pressure changes or temperatures do not cause the cap topreload the High Precision MicroJoystick. This could cause drift or directional bias.

DIVOT CAP TRACKBALL-LIKE “DOME” CAP


8.0 Electronic IntegrationCircuit for the High Precision MicroJoystick

The interface circuit for the High Precision MicroJoystick uses a minimum of commonly available com-ponents, and offers a more cost-effective and simpler interface than other types of joysticks (e.g., strain-gauge based joysticks). With its small number of components, the interface circuit for the High PrecisionMicroJoystick can easily be integrated onto a system board, or Interlink Electronics can supply an add-on interface board with the High Precision MicroJoystick. Figure 7, “Schematic - High PrecisionMicroJoystick, Application Note” details the board layout for the circuit. See Section 12.0 for details ofthe interface circuit components list.

Note: The schematic referenced above is not a universal interface solution. Additional circuitry may need to be added or component values may need to be changed to eliminate noise or counteract other electronic issues that could have a detrimental affect on the performance of the High Precision MicroJoystick. Use sound engineering practices when laying out and specifying your High Precision MicroJoystick interface circuit.


Figure 7Schematic - High Precision MicroJoystick, Application Note


9.0 Software Drivers

DOS and Windows DriversInterlink Electronics’ VersaPoint DOS, Windows 3.x and Windows 95 drivers can be supplied with theHigh Precision MicroJoystick. The driver can be supplied as source code under a software license or asobject code via a diskette (either a 3.5” or 5.25” disk). Although VersaPoint drivers are designed to maximize the High Precision MicroJoystick’s performance in DOS and Windows, the High PrecisionMicroJoystick’s Microsoft-compatible output is compatible with the standard drivers supplied withWindows 3.x, Windows 95, Windows 98, Windows NT, and Windows 2000. The High PrecisionMicroJoystick is also compatible with the standard OS/2 mouse drivers. Via the PS/2 port, the HighPrecision MicroJoystick is compatible with any common mouse driver.

Custom DriversInterlink Electronics can also supply custom mouse drivers or add special features to the standardVersaPoint mouse drivers to your specifications. For more information about custom drivers and fea-tures, please contact Interlink Electronics Product Support.


10.0 DOs and DON’Ts

DOs• Do prototype the VersaPoint system before proceeding into production. In the

prototyping phase, the lifetime, durability, manufacturability, ergonomics and performance of the High Precision MicroJoystick should all be thoroughly investigated to ensure they meet your requirements.

• Do mechanically reinforce the Z-axis pressure-sensitive adhesive joint. If Z-axis pressure sensitive adhesive is used as the connection method, a compressive force should be applied to the joint to prevent adhesive delamination.

• Do mechanically reinforce the Z-axis pressure-sensitive adhesive joint immediately after assembly. This will prevent the adhesive from delaminating and being exposed to contaminants.

• Do use an adhesive primer with Z-axis pressure-sensitive adhesives. This will help increase the mechanical strength of the joint.

DON’Ts• Do not solder directly to the exposed conductive traces. With flexible substrates,

the solder joint will not hold and the substrate can easily melt and distort during soldering.

• Do not screw into two surfaces when mounting.


11.0 High-Precision MicroJoystick™

SpecificationsPhysical Size:

Cursor Directional Control: Continuous, 360o Control

Cursor Speed Control: Smooth, continuous, and dynamic (a function of applied force)

Hardware Interface: PS/2 mouse interface standard. Others can be supported on request

Data Format: Emulates Microsoft two-button mouse

Software Compatibility: DOS, Windows 3.x, Windows95, Windows 98 – with standard Microsoft or VersaPoint software drivers. Windows NT and Windows 2000 with standard drivers.

Use Force Range: 40 ± 20g min., 150 ± 20g max. applied at extremity of 10mm stick

Stick Deflection at Full Force: 3.7o (0.65mm) approximately for 10mm stick

Stick Strength Capacity: Typical maximum side load: 20 kg (42 lbs.)Typical maximum compression load: 100 kg (220 lbs.)Typical maximum tension load: 13 kg (29 lbs.)

Lifetime (stick): Greater than 5 million cycles.

Temperature: Operating: 0oC to 60oC (32oF to +140oF) Test duration: 96 hrs. Storage: -40oC to +70oC (-40oF to +158oF) Test duration: 96 hrs.

Humidity: 5 - 95% RH, non condensing. Test duration: 96 hrs.

Power Supply: 5.0 VDC ± 10% or 3.3 VDC ± 10%

Electrical max. rating: 7.0 VDC

Power Consumption: Vcc = 5.0 V: Operating: Typical <5 mA (RMS), Max. 8 mAAt rest: Typical <3 mA (RMS), Max. 6 mA

Vcc = 3.3 V: Operating: Typical <2.5 mA (RMS), Max. 3 mAAt rest: Typical <1.5 mA (RMS), Max. 2 mA

ESD Susceptibility: IEC 801-2 Air discharge method Level 4 (no errors at 15KV)*


EMI: Passes FCC Rule Part 15, Class B Computing Device Peripheral*

Shock: 80g acceleration in 11ms*

Vibration: MIL Std. 202, Method 204 condition A*

Connection Method: Standard or custom flex circuits can be attached with anistropic (Z-axis) adhesive.

Mounting Flatness: Must be 0.0005” or flatter

UL: All materials UL grade 94 V-1 or better

CE: Conforms to 89/336/EEC

Microcontroller Specifications

Chip Family: Zilog Z86C08

Configuration: 18-pin SOIC

Clock Speed: 4MHz

Specifications are subject to change without notice* When properly integrated.


Please refer to Figure 7 in Section 8 entitled “Schematic - High Precision MicroJoystick, ApplicationNote.”

R1 68KW 5% 1/10 W

R2, R3 100KW 5% 1/10 W

R5 27KW 5% 1/10 W; See Note 1

R7, R8 5.6KW 5% 1/10 W; See Note 2

R9 56KW 5% 1/10 W; See Note 1

R11 16KW 5% 1/10 W

R12 10KW 5% 1/10 W

C1 4700pF ±10%

C2, C3 100pf; See Note 2

C4 0.1mF; See Note 3

X1 4 MHz ceramic resonator with internal capacitors; See note 4

U1 Microcontroller

Note 1: R5 provides pull up for microcontroller U1 (pin 15) to Vcc. R9 provides pull down for microcontroller U1 (pin 9) to ground.

Note 2: The values of R7, R8, C2, and C3 depend on how the device is integrated. R7 andR8 depend on the length of the signal paths between the stick electronics and the PS/2 controller and may need to be varied or removed for very long or short paths. C2 and C3 are used to suppress high-frequency noise and for ESD protection. Typically, when this circuit is integrated onto the system motherboard, R7, R8, C2, and C3 can be eliminated if the PS/2 receiver circuit already has pull-up resistors.

Note 3: This value may be adjusted to meet system requirements.

Note 4: For clock options refer to Controller Characteristics and Recommendations.


13.0 Product Support

Questions concerning the High Precision MicroJoystick should be addressed to Interlink ElectronicsProduct Support at:

Interlink Electronics Product SupportPhone: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .805-484-1331Toll free in the US . . . . . . . . . . . . . . . . . . . . . . . .800-340-1331Fax: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .805-484-5997E-mail: . . . . . . . . . . . . . . . . . . . . . [email protected]

Product Support hours: . . . . . . . . . . . . . . . .8:00 AM to 5:00 PM (United States Pacific Standard Time)

Corporate Headquarters:Interlink Electronics

546 Flynn RoadCamarillo, CA 93012 USA

Phone: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .805-484-8855Fax: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .805-484-8989

Web Site:www.interlinkelec.com


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