Dvsgt Manual v2.6

8/3/2019 Dvsgt Manual v2.6

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Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The importance of drivers vision testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Night vision often overlooked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The DVS-GT: Features and Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

About the test instrument. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Giving the Exam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Test preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Running the tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Test Questions and Referral Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

More tips for the examiner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Routine Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

IMPORTANT NOTICE: The instrument isheld closed by a magnetic latch. To free the latch, placethumbs on top edge of base and press up on bottom ofchassis (see illustration).

DO NOT lift up on black eyeshield

assembly.


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The importance of drivers vision testing

Vision gives us control over our environment. A significant amount of the information we learn comes through our eyes. For children,adequate vision is essential for normal development and learning. For adults, adequate vision is essential for safety, job performance,entertainment and everyday life activities.

An estimated 40% of people in the United States have some kind of vision dysfunction. Fortunately, it is also believed that up to 95%

of these individuals can attain adequate vision through corrective or therapeutic measures.

Vision testing and therapy facilitates this task, quickly indicating if a persons vision falls within the acceptable standards of good see-ing - and if he or she would benefit from a comprehensive exam and vision therapy.

Glare recovery often overlooked

Conventional drivers vision screening tests for acuity, depth perception, colour blindness and night vision. But often one crucial real-life visual function is overlooked glare recovery. This is the ability of the eyes to quickly re-adapt to darkness after encountering asudden, bright light.

For example, an individual drives down a dark road and suddenly encounters the high-beam headlights of another vehicle. The eyespupil, which has been wide open to gather in the sparse light of night conditions, is now flooded with light and temporarily blinded.Glare recovery is the speed and efficiency by which the pupil re-adapts to night conditions an important skill when one is steering a

2-ton vehicle at speeds over 70 miles per hour!

Contrast sensitivity

Contrast sensitivity measures the ability to see details in this case curbs, pedestrians, traffic signs - when the luminance level of thedetails does not vary much from the luminance level surrounding it, such as the background of a sign. Examples of low contrast condi-tions include adverse driving conditions like fog, darkness and snow. Contrast sensitivity is a very different visual function than acuity;a person with 20/20 acuity under high contrast conditions may have the equivalent of 20/400 or worse in low contrast conditions.

The DVS-GT contrast sensitivity targets show images at different levels of contrast, using reflective light to mimic real world vision.For measuring results, a person who is able to detect details in very low contrast conditions is said to have high contrast sensitivity;conversely, a person who cannot detect details in very low contrast conditions is said to have low contrast sensitivity.

The DVS-GT: Features and CapabilitiesAfter nearly 50 years producing its popular screening instruments for drivers licensing agencies, Keystone View developed the firstdrivers vision screener with glare testing capabilities for the Department of Transportation in Nova Scotia, Canada. Since then, de-mand for this important drivers safety feature inspired launch of a new product: The DVS-GT.

The glare recovery test gauges a subjects ability to adapt to decreased illumination and to recover from exposure to glare just as adriver would need to do under night highway conditions. Targets feature international road signs, with United States and United King-dom versions currently available. Seven numbers are presented in a column; if at least six are not correctly identified by the subject,further examination by a vision professional (optometrist or ophthalmologist) is recommended.

Note: Because no official standards have yet been set for the glare recovery test, failure to correctly identify 6 or more targets shouldbe reason for concern but not the sole reason for denial of a drivers license.

The DVS-GT offers a 9-test sequence that evaluate the following areas of visual function:

Acuity Tests 1, 2 and 3 screen the right and left eyes separately and together.

Colour vision Test 4 identifies the ability to differentiate between red, green and yellow traffic signal colours.

Phoria Test 5 determines if ones eye muscles are properly balanced and coordinated.

Depth perception/Sign recognition In test 6 subjects are asked to both identify a total of 6 road signs and determinewhich ones appears closer.

Contrast sensitivity Test 7 evaluates the subjects ability to discern objects under low light dawn and dusk drivingconditions.

Glare recovery Test 8 tests the subjects ability to first adapt to decreased illumination (night driving) and to recoverrapidly from exposure to glare (oncoming headlights).

Horizontal peripheral visual fields test Identifies tunnel vision a grossly-restricted peripheral vision field.

INTRODUCTION

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About the Test Instrument

The DVS-GT is designed for both standardized and completely confidential testing. Targets are enclosed in the unit, so subjects can-not see or study them in advance. Internal target illumination ensures consistency of operating conditions, and the unit pivots througha 63-degree arc to adjust to the eye level of any subject.

Only 25 cm (10 inches) wide, 39 cm (15 inches) long and 17 cm (7 inches) high, the DVS-GT is compact and completely self-contained. When not in use, ,a magnetic catch holds the unit closed. Total weight is less than 5 kg (11 pounds). The DVS-GT oper-ates from standard 110 or 220 volt a.c. power.

1. Headrest: Accommodates a wide variety of eyeglass frames. During testing, the subjects forehead should rest lightlyagainst this specially-designed strip.

2. Peripheral vision test: Horizontal peripheral vision fields are measured using light-emitting diode target lamps, posi-tioned between the lenses and recessed in the temple areas of the viewing head so that eyeglass frames will not inter-fere with testing.

3. Control unit: By pressing appropriate buttons, the examiner can advance or reverse the test targets, occlude either ofthe subjects eyes and control target illumination. Designed for hand-held or desk-top operation, the unit is 11 cm x 14.5

cm x 2.5 cm (4 3/8 x 5 x 1) and weighs 2.5 kg (8 ounces).

4. Observation windows: Instrument cover slides back to expose these viewing windows, which allow the examiner tosee the target being viewed by the subject and to use a pointer if necessary.

5. Power Switch: The off-on power control is located on the rear of the instrument.

6. Power Supply: To eliminate electrical and heat hazards, power is converted to 12Volts DC. To ensure safe operation ofthe equipment, the instrument must only be used with the transformer supplied by the manufacturer. Use of any other

transformer that has not been approved by the manufacturer could result in safety problems.INPUT: 110 or 220 VAC OUTPUT: 12 VDC

The Class II symbol on the transformer label indicates that the transformer does not only rely on basic insulation to pro-tect against electric shock, but has double insulation as an additional safety precaution, there being no provision for pro-tective earthing or reliance upon installation conditions.

Environment Operating temperature 0~40C Storage temperature -20~70C

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1

2

3

4

5

6

Symbols

Type B Device In accordance withDirective 93/42/EEC


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A. Lists stereo tests. A lamp next toeach test indicates the target beingpresented.

B. Illuminates peripheral vision targetlamps. A signal lamp indicates theeye being tested.

C. Controls occlusion for each eye.Hold the button down continuouslyto turn off the target lamp.

D. Advances the stereo target drum tothe next drum. Hold the buttondown continuously to keep advanc-ing the drum.

E. Reverses the stereo target drum tothe previous test. Press and re-lease the button to go back to theprevious test.

F. Activates lighting for the glare re-covery test.

G. Activates reduced illumination/nightvision conditions.

The DVS-GT adjusts effortlessly tothe eye level of any test subject. Itpivots through a 63 arc with freefloating action fully controlled by thesubject. (When not in use, a mag-netic catch holds the unit closed).

Target drum and illumination lamps,are readily accessible by removing thetop cover of the case. The drum ac-commodates eight permanently-mounted stereoscopic tests whichmay be removed if required underspecial circumstances.

A convenient storage area, accessi-ble from the rear, is built into thebase of the instrument. The instruc-tion manual and record forms maybe stored here when the DVS-GT isnot in use.

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A

C

E

D

F

B

G


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Under normal use conditions, the DVS-GT instrument requires minimum attention if it is protected by the dust cover when it is not inuse. Virtually no repair or adjustment is needed, since all operating components are protected and solid-state circuitry assures excep-tionally high reliability.

CleaningPeriodically, some cleaning will be necessary. The main instrument housing and control unit should be dusted from time to time with asoft cloth or brush, and the lenses washed with soap and water dampened cloth and dried with a soft cloth or tissue.

If the instrument has become very soiled, it may be cleaned with a mild soap-and-water dampened or general purpose cleaner damp-ened cloth. (Other solvents are not recommended).

Be sure to disconnect the unit from its power supply before cleaning.

Lamp ReplacementTwo Nichia NSPW515BS Daylight LED lamps provide illumination of the stereo targets. Although they are rated for over 100,000hours of continuous use, replacement may eventually be required.

Remove the instruments top cover. Turn power switch on to check condition of the lamps. Make sure the bulb contacts are touchingthe metal lamp clips. (Please bear in mind that when one lamp fails, the second will probably fail within a short period. Another sparebulb should be available).

The Glare Recovery Test uses 2 super-bright white daylight LEDs rated at over 100,000 hours. These LEDs should never need re-placement during the life of the machine.

The peripheral vision test targets in the viewing head and the red signal lights on the control panel are light-emitting diodes (LEDs).They are designed for extremely long life and should not require replacement during the lifetime of the DVSGT.

Fuse ReplacementA standard ONE ampere automotive-type fuse is incorporated in the circuitry of the DVS-GT to protect the unit against possible electri-cal malfunction. Should replacement ever be required, order an 8 AG 1 amp. Fuse (1,25 inches long) from your distributor (Part No.297-258).

Installation And Synchronization Of The Stereo Test Target DrumThe DVS-GT Screener is shipped ready for operation, with the target drum installed and synchronized with the control panel. It isrecommended that instrument owners do notremove the drum except for replacement or in an emergency situation.

Drum removal: If removal is required, (Wear light cotton gloves or use a facial tissue to protect the stereo target areas from finger

prints. Try to handle the drum near the end cap gears) push the spring clips, A and B, outward from the ends of the drum. Slidethe drum towards the rear of the instrument - away from gears C and D - and lift it out.

Drum replacement and synchronization:

1. Turn power switch on. Slowly rotate gear C until gear D stops moving. Observe which red signal light on the control panel islit: This shows how the drum is to be installed.

2. To synchronize the target drum with the control, the drum must be inserted with the corresponding target facing the lens openingat the front. Insert the drum downward between the spring clips(A and B); slide it forward toward the lenses until the clips snapin toward the drum. The drum gear cogs should now be engagedwith gears C and D.

3. Press the test advancebutton on the control to move the drum tothe next target. Look through the lenses to determine if the targetis centered vertically in the lens openings.

4. If a centering adjustment is required, move only spring clip Aaway from the drum and move left end of the drum backward andaway from gear C. Gear C mustbe disengaged from the drumcogs. Rotate drum backward or forward to accomplish adjust-ment. Snap drum back into position, re-engaging gear C. Re-check target alignment by looking through lenses.

5. Repeat step 4 if required.

DVS-GT MAINTENANCE

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A B

C

D


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GIVING THE EXAMTest preparation

The testing area: Though often a separate vision testing room is not available, DVS-GT testing should be given in a reasonably quietarea to avoid distractions and interruptions that may interfere with the accuracy or speed of the examinations. Subjects should beadmitted from the waiting area into the test area one at a time, to prevent those waiting to be examined from overhearing spoken com-ments or remarks that could impact the validity of their examinations.

Position the DVS-GT unit near the edge of the table or counter at a height that allows for a comfortable 4-5 minutes of testing of sub-jects in an average height range. The examiner can stand or sit anywhere in the immediate vicinity of the subject that provides com-fort and sufficient working space.

Equipment readiness: At the beginning of the work day, dust the DVS-GT and lenses with a soft, soap and water-dampened clothand examine the unit against the following checklist:

Is the unit transformer connected to a standard arc. outlet? Do both target illumination lamps light up when the powerswitch is turned on?

Is the drum holding the test targets properly synchronized with the control unit?

Do the horizontal field target lamps light up when the appropriate buttons on the control panel are selected?

Does the appropriate target illumination lamp go out when each of the occlude buttons is selected?

Do the illumination lights on both targets dim when the night vision button is selected?

Do the glare recovery lights illuminate when the appropriate button is activated on the hand control unit, and when nightvision is activated?

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Instructions for the subject: Good posture is essential for accurate test results; the strain of standing in an uncomfortable positionwill cause a subject to be distracted during the exam. The subjects forehead should rest comfortably against the headrest throughoutthe examination, without pulling back or away from the instrument between individual tests, or tilting the head to the side. The subjectcan directly control adjustment of the height and angle of the DVS-GT during the exam and may feel more comfortable grasping theside of the unit with one or both hands with elbows resting on the desk or counter.

If the subject normally wears glasses or contact lenses while driving, these should be worn during the examination. If correctivelenses are only worn for reading or distance vision, they should be removed for tests that do not deal with these vision areas.

Running The Tests:

Test Guide

Eleven tests evaluate 9 visual functions important to driver safety. All are given at far point at the equivalent of 6 meters (20 feet).The test series can be completed in only 3-5 minutes.

The examiner administers all test operations through the push-button remote control unit. During testing, the subject stands or sits infront of the DVS-GT testing instrument and positions his or her face against the viewing head to observe the test targets. Any glassesor corrective lenses normally used when driving should be worn.

After the examiner briefly explains the purpose of each test (explained below), the subject reports what he or she sees, and the exam-iner records these answers using special Keystone View DVS-GT record forms.

Tests #1, #2 and #3: Acuity

To test acuity (fineness of visual discrimination), blocks of digits are presented for identification by the subject, testing the right eye(test #1) and the left eye (test #2) then both eyes together (binocular test #3). Test #1 tests the acuity of the right eye while the lefteye is open and seeing. It tests at far point and results are calibrated at values from 6/60 to 6/6 (20/200 to 20/20). Test #2 similarlytests the acuity of the left eye while the right eye is open and seeing. It tests at far point and the results are calibrated at values from6/60 to 6/6 (20/200 to 20/20). Test #3 screens binocular vision at far point as well as night vision. It presents the same number groupsto both eyes simultaneously and provides seven rating ranging from 6/60 to 6/6 (20/200 to 20/20). All three acuity targets employSloan-type numerals without serifs.


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Test #4: Colour Vision

The subject is shown 12 coloured circles designed to identify problems identifying red/green/yellow traffic signal colours. The correct

colours are to be read back by the examinee are printed in black on the control key. All four colours presented on each line shouldbe identified by the subject, should the subject miss more than one of the colours further examination by a vision profes-sional may be advised.

Test #5: Binocular Coordination (Phoria)

This simple test determines if the subjects eye muscles are properly balanced and coordinated. A passing response tothe question, Is the dot inside or outside the box? will be, Inside the box. It is completely normal for the subject to seethe dot move around a bit; however, its movement should slow down to a limited range after a few moments.

Tests #6: Depth Perception and Sign Recognition

Subjects are asked to both identify 6 road signs (at least 5 correctly to pass) and determine which of the 2 appearscloser. Both the closest and the farthest sign should be identified to gauge if the subject has normal depth perception.Correct answers are available to the examiner on the control screen.

Test #7: Contrast Sensitivity

Tests the driver's ability to discern objects under a variety of lighting conditions (e.g., dawn, dusk and low light night driving condi-

tions). Subjects are presented 9 blocks of numbers varying in contrast from 10 to 90 percent under dusk, night driving

conditions. If the test subject is unable to correctly identify all three numbers in the 40% block further examination by avision professional is recommended. (No minimum standards have been set yet for this test.)

Test #8: Glare Recovery

Tests the driver's ability to adapt to decreased illumination and to recover rapidly from exposure to glare such as onewould be exposed to driving at night. Subjects are presented a 3 rows of 7 numbers shown under decreased (night)illumination, glare and then a return to night illumination to gauge visual recovery from glare. If at least 6 of the 7 num-bers in a row are not correctly identified, further examination by a vision professional is recommended.

Currently no standards have been set for the Glare Recovery test. This means that although the test subject isunable to pass this test as given he/she should not be denied a license solely on the outcome of this screening.

Test #9: Horizontal Peripheral Vision/Field Testing

Miniature lamp (LED) targets between the lenses and recessed in the temple (side) areas of the viewing head show howfar to the side a subjects visual field extends when (s)he looks straight ahead. Persons with tunnel vision, a grossly-restricted peripheral field, are quickly identified. The targets are selectively lit by individual buttons on the control panelto show a 45 nasal field and to check temporal fields at angles of 85, 70, and 55. (A total field of from 100 to 130can be measure for each eye). The eyes may be tested separately or together.

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Tests #1, #2 and #3: Acuity

Ask your subject to read the first block of characters, Column A. If they are read correctly, he/she has 20/20 acuity and needs not

read any further. Five of six characters must be read. Continue across each row, from left to right until the test subject reads thecharacters in a block successfully.

Compare the actual test presentation with the key card on the control. Notice that the key card has added the symbols 20=, 25=,30= and so forth. This indicates the acuity level associated with the corresponding test characters: 20/20, 20/25, 20/30, etc. Forexample, in row 1 column b, 25= indicates that the acuity level tested here is 20/25.

Be sure to instruct the subject to keep both eyes open at all times. He/she may report that no characters are seen, in which case avisual suppression is evident, and the subject should be referred for a full professional eye examination.

Right eye

Test Target

Control Key

Left eye

Test Target

Control Key

Test Questions and Referral Guide

Notes: All tests are given with both eyes open at all times. Subject should wear any glasses or contact lenses nor-mally used for driving. Double check the day/night switch for the desired position.

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Right eye: Acuity

A1. 20 = 5476382. 40 = 7958233. 70 = 9574

B25 = 42857650 = 537248100 = 92

C30 = 94385260 = 7236200 = 5

Left eye: Acuity

A1. 20 = 7459322. 40 = 5342683. 70 = 8453

B25 = 57823650 = 752386100 = 85

C30 = 34675260 = 6254200 = 3


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Binocular

Test Target

Control Key

To pass the acuity test, at least five of the six characters must be read in block a, line 2 of test 5, 6 and 7. There is a standard of20/40 for each eye separately as well as for both eyes together. This standard corresponds to most U.S. State requirements.Business and industry may have more strict requirements that must be considered.

Test #4: Colour Deficiency

Actual Test

Control Key

Ask the subject: What colours do you see in the four circles in row A, B, C, D? Correctly naming all colours in all thecircles is the minimum acceptable answer. Missing one or more may indicate some possible colour blindness.

BEST TO GIVE HORIZONTAL PERIPHERAL FIELD VISION TEST NOW.

Colour

A - Y G R G

B - R Y R G

C - G Y Y R

D - G R G Y

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Both eyes: Acuity

A1. 20 = 8574322. 40 = 5634723. 70 = 2978

B25 = 67423550 = 859423100 = 43

C30 = 38245760 = 8927200 = 9


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Test #5: Phoria

Test target

Control key

Ask your subject: Is the red dot inside or outside the yellow box? If the dot is outside the box, a referral should be made for a fullprofessional eye examination.

Note: Some subjects will see only the red dot or only the yellow box. This indicates they are using only one eye, either because the

other eye is blind or lazy, or because they have some other kind of binocular vision problem. In any such case, unless the subjectalready knows he/she has such a defect, he/she should be referred for a full eye examination.

Tests #6: Depth Perception and Sign Recognition

Actual Test

Control Key

Ask the subject: Please identify all six road signs. What do they mean? Do any appear closer to you than the others? Whichones? Do any appear further away from you? Which?

Phoria

Dot inside box

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Depth/Sign

1. No Right Turn2. Level Crossing Near3. Give Way

4. School Crossing Far5. Speed Limit6. No Overtaking


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Test #7: Contrast Sensitivity

Actual Test

Control Key

Note: Make sure the day/night switch is in the appropriate position. Be sure to instruct the subject to keep both eyesopen at all times. Ask your subject to read the numbers on Line 1 Column A. If they are read correctly, he/she has theability to read a 20/70 acuity test at 10% contrast and they need not read any further. . Continue down each line readingeach block from left to right until your test subject reads all three numbers in a single block successfully.

Compare the actual test presentation with the key card on the control panel . All tests are given at 20/70 acuity. Line 1column A is 10% contrast, Line 1 Column B is 20% contrast, Line 1 Column 3 is 30% contrast and Line 2 Column A is40% contrast. Reading a minimum of all three numbers on Line 2 Column A is considered acceptable.

Please note that at this time no standards for Contrast Sensitivity have been set. This means that although thetest subject is unable to pass this test as given he/she should not be denied a license solely on the outcome ofthis screening.

Test #8: Glare Recovery

Actual Test

Control Key

Note: Make sure the day/night switch is set to the night position. Test will not operate in the day position. Be sure to in-struct the subject to keep both eyes open at all times.

Tell the subject you will be flashing a light in their field of view and when it goes out they are to read the line of numbers

you instruct.

To perform this exam you will press the orange glare switch on the control panel. This will illuminate the glare lamps fora period of 3 seconds. Once the glare lamps go out the test subject is to read without delay one of the three lines yourequest. Reading six of the six of the seven numbers in any one line in less than 5 seconds is considered passing.

Please note at this time no standards for Glare Recovery have been set. This means that although the test sub-ject is unable to pass this test as given he/she should not be denied a license solely on the outcome of thisscreening.

Contrast SensitivityA

1. 9 5 82. 3 4 73. 4 2 6

B4 7 95 6 37 2 8

C8 6 35 3 49 6 2

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Glare Recovery test

1. 2 6 5 1 4 3 9

2. 8 2 9 4 6 3 5

3. 6 3 9 5 2 7 4

1

3

2

1

3

2

2 6 5 1 4 3 9

8 2 9 4 6 3 5

6 3 9 5 2 7 4

2 6 5 1 4 3 9

8 2 9 4 6 3 5

6 3 9 5 2 7 4


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Test #9: Horizontal Field Testing

This test is best given following the Colour Test. The subject is told to keep looking at that test panel and focus on one of the colouredcircles.

Tell the subject that, at any time, a light may flash to the left or right side. The subject should respond left side or right side. TheN button tests 455 degrees across the nose, in the nasal field. (Testing right eye nasal will yield a left side response.)

For a one-eyed driver, a range, or peripheral vision, should be tested. Do this by depressing both the N and 70 degree buttons forthe eye in question. A response of both sides or two lights is expected.

Subjects should be able to respond to at least the 55 degree and 70 degree temporal tests for each eye. If they cannot, visual prob-

lems may exist, and referrals should be made for a full professional eye examination

85 70 55 N N 55 70 85

HORIZONTAL FIELD

More tips for the examiner

The DVS-GT is designed to conduct drivers vision testing in a highly standardized and sequential fashion to ensure consistent results.However, a subjects visual skills rating also can be significantly impacted by the attitude of the examiner. The examiners goal needsto be to evoke from the subject the most accurate testing responses possible.

Record basic subject identification information before beginning the actual series of vision tests

Encourage the subject to be as frank as possible in telling what he or she sees.

During testing, keep conversation to a minimum to avoid unconsciously leading the subject into a certain kind of re-sponse.

Acknowledge each response but be careful not to indicate approval or disapproval.

Note that subjects with vision problems might exhibit slower test responses. Be sure to allow sufficient time.

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With normal usage, the only maintenance the DVS-GT should require is the possible replacement of the instrument testing lamps.The instrument lamps can be accessed for replacement by removing the top cover of the DVS-GT unit, attached to the instrument byfour easy to remove screws. Replacement LEDs can be ordered directly from Keystone View or your local distributor.

If carrying the instrument long distances, Keystone View recommends transporting it in its specially-designed carrying case. (product#1140)

To minimize cleaning and exposure-related damage, always protect the DVS-GT with its dust cover when not in use. Dust the unitperiodically with a soft brush or cloth, or a mild soap and water solution. Lenses should be cleaned with a lens tissue or cloth. Be sureto dry all components completely before storage.

Notes about sensors

Note:

The head position sensor incorporated in some Keystone Vision Screeners may occasionally malfunction when the instrument is usedin areas of very bright ambient lights. If this occurs, the target illumination lamps inside the instrument may not light or light erratically.

The sensor function may be overridden with a slide switch located in the rectangular hole under where the control cable plugs into thescreener. The switch slides up to turn the sensors on and down to turn the sensors off.

1) To override the sensor function, using an open paper clip or similar object slide the switch down toward the bottom of theinstrument. The target illumination lamps visible through the open hatch in the top of the screener will light when the instrument powerswitch is in the ON position. The target illumination lamps will now remain ON whenever the power switch is ON.

2) To activate the sensor, slide the head position sensor switch toward the top of the instrument. To check operation of the sen-sor, cover the plastic window located on the inside right side of the eye shield. The target illumination lamps will light.

ROUTINE MAINTENANCE

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2200 Dickerson Road, Reno NV 89503Phone: (775) 324-2799 (800) 806-6569

Fax: (775) 324-5375 (800) 893-9018Email: [email protected]

Documents

Dvsgt Manual v2.6