JP2001087225A - Night vision optometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical night vision optometer capable of simplifying the structure of the device and miniaturizing the device. SOLUTION: This optometer bas a nighttime eyesight test means and a regular eyesight test means. The nighttime eyesight test means measures the nighttime eyesight or the time required for an eye to be tested to judge an eye-chart index, which is presented with low brightness in a dim visual field after light adaptation of the eye to be tested. The regular eyesight test means measures the eyesight with an eye-chart index presented in a space with normal brightness. A white LED is used for the light source of the eye-chart and the brightness of one LED can be varied at least by ten times to plural brightness values by controlling an electric current to the LED according to the use of the eye-chart in the eyesight test.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a night vision meter used for driving aptitude test and the like.

[0002]

2. Description of the Related Art After an eye to be examined is adapted to light, an optotype is presented in a dark visual field supposed at night, and the visual acuity of the examinee can be measured, or until the optotype can be identified. A night vision meter that measures the time of the night is known. The luminance of the presented target at the time of the night vision test is 0.5 cd / m for the type that measures the target visual acuity that was identifiable.
^In the type that measures the time until the target can be determined, the target is presented in a state where the target luminance is low, such as about 0.15 cd / m ² .

In evaluating night vision, it is necessary to consider the relationship with normal vision, and at the same time, it is necessary to present a target at normal brightness and to examine the maximum visual acuity value that can be distinguished. It is configured. The luminance of the presented target at the time of the normal visual acuity test is about 250 cd / m ² .

[0004]

As described above, there is a difference of 1000 times in the luminance of the target between the night vision test and the normal vision test even when the same target is presented. Conventionally, a tungsten lamp or a halogen lamp has been used as a target light source. However, in this type of lamp light amount adjustment, a difference in color temperature occurs, and one light source sets the brightness with a difference of 10 times or more. It was difficult. Therefore, the lamp light sources are prepared by the number of brightness required for the target, and the target is illuminated through the half mirror or the light amount is adjusted by the filter. There was a problem of becoming.

Further, a halogen lamp or the like generates a large amount of heat. In order to cope with this, it is necessary to provide a large space around the lamp light source and to provide a heat radiating mechanism so that heat is not transmitted to the outer cover.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional apparatus, it is an object of the present invention to provide a night vision apparatus that can simplify the apparatus configuration and reduce the size of the apparatus and is economically advantageous.

[0007]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) After the subject's eye is subjected to light adaptation, a target is presented in a dark field of view with dim luminance, and the night vision or the time until the target can be discriminated is measured depending on the appearance. Equipped with an inspection means and a normal visual acuity inspection means for measuring visual acuity when presenting an optotype in a normal brightness space, using a white LED as an optotype light source and according to the purpose of the optotype in each test. By controlling the current to the LED, the brightness of one LED can be changed to a plurality of brightness of at least 10 times or more.

(2) In the night vision meter of (1), there is provided a glare visual acuity test means for presenting a visual target under glare and inspecting the visual acuity according to the appearance thereof. It is characterized by further changing the length.

(3) The night vision meter of (1), further comprising control means for variably controlling the brightness of the LED in accordance with the lapse of the time measured by the night vision inspection means.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the appearance of a night vision meter according to the present invention.

Reference numeral 1 denotes an apparatus main body, and a binocular inspection window 2 (2R, 2L) is provided on the upper part of the apparatus main body 1 for a subject to look into an optotype presented inside the casing of the apparatus. An operation panel 3 having various switches and a printer 8 are arranged on a side surface of the apparatus main body 1. In addition, a joystick (lever) 5 for allowing the subject to respond in the direction to the optotype presented inside the main body, and a response that the optotype can be read is provided on the front side of the lower portion of the apparatus main body 1. A button 4 used at the time is provided. Reference numeral 6 denotes a start switch in the automatic inspection mode, and reference numeral 9 denotes a speaker to which a voice guide instruction is output.

FIG. 2 is a schematic view of the optical system disposed inside the apparatus when viewed from the side, and also shows the configuration of the control system. FIG. 3 is a schematic view of the optical system inside the apparatus when viewed from above.

Lenses 10R and 10L are disposed in the left and right inspection windows 2R and 2L, respectively, and the optotype target windows 15R and 1R are provided.
The test target which is switched and arranged to each of 5L is the eye E
The inspection distance is apparently 5 m from R and EL. The left and right optical paths are cylindrical inner covers 11R having a partition plate at the center,
11L, the visual field space in which the left and right eyes see the optotype is individually secured. This inner cover 11R, 1
1L have the same shape, the left and right inner wall surfaces are formed symmetrically about the respective central axes 01R and 01L of the inspection windows 2R and 2L (the respective optical axes of the lenses 10R and 10L), and are viewed from the rear. The mark windows 15R and 15L are also provided at the same position. Therefore, the inspection windows 2R and 2L can be seen by both eyes.
When observing the inside through the eye, the two optotype windows 15R and 15L are fused to be seen as one, and the inner covers 11R and 11L are similar to when observing the inside with the left and right eyes alone.
L is also observed as one space with the left and right walls in the same state. For this reason, the subject can see the test target placed optically at a long distance (5 m) without any discomfort.

The optotype presenting section 20 for switching and arranging the test optotypes in the optotype windows 15R and 15L includes a single optotype disc plate 21.
, A pulse motor 22 for rotating and driving the optotype disc board 21, and white LEDs 24R and 24L as optotype light sources for illuminating the optotype on the optotype disc board 21. L
Since the ED generates less heat and has a much longer life than a halogen lamp or the like, even when the apparatus is used for a long time, the light source does not need to be replaced.

The target disc plate 21 is made of a glass substrate having a light-transmitting property.
Landolt visual targets in four directions of left, right, up, and down are formed of a chrome coat having a light shielding property in 12 steps of 1.2 and 1.5. The test target is formed so as to correspond to the positional relationship between the two target windows 15R and 15L so that the same target for right eye presentation and left eye presentation can be simultaneously presented to the left and right eyes. . In addition to the test target, the target window 15 is provided on the target disk plate 21 at the time of light adaptation in the night vision test.
A shielding plate for shielding R and 15L is provided.

The target on the target disk 21 is a motor 22.
The target pair 15R, 15
L, each target is illuminated by the LEDs 24R and 24L. When the visual acuity is measured, the test target is presented at a luminance of about 250 cd / m ² by turning on the LEDs 24R and 24L. At the time of measuring the visual acuity recovery time, the light quantity of the LEDs 24R and 24L is reduced to generally provide about 0.15 cd / m ² . The test target is presented with dim brightness. LED2
The light amount adjustment of the 4R and 24L is performed by controlling the supply current by the dimming circuit 25 in accordance with an instruction from the control unit 30.

The inner surfaces of the inner covers 11R and 11L are coated with matte white paint, and the illumination light sources 12R and 12L are turned on during normal eyesight measurement, and the illumination light sources 13R and 12R during light adaptation for night vision inspection. 13L are turned on, and each is illuminated to a predetermined brightness. These light sources are located at positions where the illumination light does not directly enter the eye to be examined. Light sources 14 (having a brightness equivalent to a vehicle headlamp) that are turned on when measuring visual acuity under glare are arranged on the left and right of each of the target windows 15R and 15L. As this light source, a white LED can be used as described above. The glare undersight measurement is performed by turning on the light source 14,
It examines the effect of visual acuity when it is dazzled by headlights of oncoming vehicles while driving a car at night.

In FIG. 2, reference numeral 30 denotes a control unit for controlling the entire apparatus.
In addition to the voice guide generating unit 31, the response button 4, the joystick 5, the operation panel 3, and the like, which are connected to the memory 33, a memory 33 storing an inspection program is connected.

Next, the operation of the apparatus having the above configuration will be described. The apparatus includes a manual mode, an automatic mode (a mode in which the test program is advanced by the subject operating the joystick 5 or the like according to a voice guide), a semi-automatic mode (a verbal response of the subject to the automatic mode). (A mode in which the test program is advanced by the examiner inputting the contents), and three test modes are prepared, and any one of them can be selected by the mode selection switch 40 of the operation panel 3. Hereinafter, the inspection in the automatic mode will be described. The automatic mode is a normal eyesight measurement (5
m eyesight measurement), eyesight recovery time measurement (night vision test), and glare-based eyesight measurement are sequentially programmed, and the examiner specifies the eye to be measured by the switch unit 41 in advance. Measurement eyes can be specified as right, left, and both eyes.
Here, it is assumed that both eyes are designated.

When the subject presses the start switch 6, normal visual acuity measurement is first started. The control unit 30 turns on the light sources 12R and 12L to turn on the inner covers 11R and 11L.
Is set to have a luminance of 25 cd / m ² . In addition to controlling the driving of the pulse motor 22 and controlling the lighting of the LEDs 24R and 24L via the dimming circuit 25, the target window 15 is controlled.
A target having a visual acuity value of 0.5 is presented on R and 15L with a luminance of about 250 cd / m ² .

When measuring the visual acuity, if the direction of the visual target can be determined by the voice guide, the subject can use the joystick 5
Is instructed to fall in that direction. When the subject responds to the joystick 5 with the result of the discrimination of the target, the control unit 30
The right or wrong is determined by If the response is correct, an optotype with an increased visual acuity value is presented, and if incorrect, an optotype with a reduced visual acuity value is presented. If the answer is raised by one step or the judgment cannot be made (if the answer is unreadable, the response button 4 is pressed), the visual acuity value is returned to the visible level, and the test is continued by changing the direction of the target. As a result of the determination of correctness by the control unit 30, if there is a correct answer twice or more with the same visual acuity target, the visual acuity value is determined as having the visual acuity.

Subsequently, a program for measuring the visual acuity recovery time is executed (see flowcharts in FIGS. 4 and 5). After the voice guide announces that the lamp is turned on and becomes brighter for 30 seconds, the light sources 13R and 13L are turned on to illuminate the visual field space seen by the subject's eye, and the time measurement for making the subject's eye light-adapted is started. . During this time, the optotype windows 15R, 1
A shielding plate provided on the optotype disc plate 21 is placed on 5L.

When approaching the end of the light adaptation time, a voice guide announces that "after darkening, immediately turn the lever in the direction in which the ring is cut off when the target is visible." After the end of the light adaptation time, the light sources 13R and 13L are turned off, and an optotype having a visual acuity value of 0.2 is placed in the optotype windows 15R and 15L.
L gives a dim luminance of about 0.15 cd / m ² . The control unit 30 measures the time from the start of the optotype presentation, and checks the response input of the interpretation result by the joystick 5. Here, when there is no response input even after the lapse of 60 seconds (the same applies when the response is incorrect), the target luminance is increased to twice the initial brightness (about 0.30 cd / m ² ). . When there is no response input even after 70 seconds, the optotype luminance is increased to the first three times the brightness (about 0.45 cd / m ² ), and after 80 seconds, the first four times the optotype is increased. Increased brightness. After the elapse of 60 seconds, not only is the time taken to complete the measurement extended, but also
By sequentially increasing the optotype luminance every second, the possibility that the examinee who cannot respond with the initial optotype luminance can visually recognize the optotype increases. When 90 seconds have elapsed, the measurement result is "90 seconds elapsed", and the measurement is terminated.

When there is a response input from the joystick 5, the control unit 30 determines whether it is correct or not. If the response is wrong and it is the first time (if it is not twice in succession), the direction of the test target to be presented is changed, and then "Please tilt the lever in the direction in which the ring is broken" Is announced, and the measurement is continued. If the response is incorrect, the visual target cannot be visually recognized, and therefore, is not treated as a measurement result. Then, when a response is input again and the response is an error twice consecutively, re-measurement from light adaptation is automatically performed. Note that the re-measurement is performed only once, and even if the re-measurement is performed, if the response is incorrect twice consecutively, the measurement is stopped, and the measurement of the visual acuity recovery time is terminated.

It is determined that the response input by the joystick 5 is a correct answer. When the answer is the first time (when two consecutive correct answers are not given), the direction of the test target presented in the same manner as described above is changed. An announcement stating that "Please tilt the lever in the direction in which the wheel is cut" is issued. Then, when the next response input is the correct answer again and it is within 5 seconds from the response of the previous correct answer, it becomes two consecutive correct answers, and the subject judges that the optotype can be visually recognized. Since it is possible, the measurement time at the time of the first consecutive response is taken as the measurement result (eyesight recovery time). Here, if 5 seconds have elapsed since the response to the previous correct answer, the previous correct answer has low reliability (in other words, if the target can be visually recognized at the time of the previous response, the next presentation Since the response of the target can be performed quickly, the previous response is treated as an error without using two consecutive correct answers, and the time of the current correct answer is set as the time of the first correct answer.

As described above, when there are two consecutive correct answers, the reliability of the measurement result can be improved by using the initial response time as the visual acuity recovery time. In addition, since the measurement is continued as it is for one wrong answer (when it is not two consecutive wrong answers), it is not necessary to perform the re-measurement uselessly.

When the measurement of the visual acuity recovery time is completed, the visual acuity under glare is measured next. After the subject is instructed by the voice guide to gaze at the target and respond in the direction of the presented target, the light sources 14 on both sides of the target windows 15R and 15L are turned on. An optotype having a visual acuity value of 0.5 (or an optotype having a visual acuity value finally determined by normal visual acuity measurement) is provided at the optotype windows 15R and 15L by the LEDs 24R and 24L at 10 cd / m.
Presented with about ² brightness. Then, similarly to the normal visual acuity measurement, the correctness of the response content is determined by the control unit 30.
Based on the result, the next presentation target is determined. If there is a correct answer twice or more with the same visual target, the visual acuity value is determined as having the visual acuity.

When the inspection is completed, the printer 8 automatically prints out each measurement result, the judgment result of each measurement, and the contents of the general instruction.

[0030]

As described above, according to the present invention,
By using a white LED as the target light source and controlling the current to this LED, there is no problem of the color temperature, and a single light source can set a plurality of brightnesses including a luminance difference of 10 times or more. . This can simplify the configuration by omitting the number of light sources and unnecessary optical elements, and can also improve maintainability. Further, the amount of heat generated from the target light source can be reduced, and a compact device can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an external appearance of a night vision meter according to the present invention.

FIG. 2 is a diagram showing an outline of an optical system disposed inside the apparatus when viewed from a side, and an outline of a control system.

FIG. 3 is a schematic diagram of an optical system inside the device when viewed from above.

FIG. 4 is a flowchart illustrating measurement of a visual acuity recovery time.

FIG. 5 is a diagram illustrating a flowchart illustrating measurement of a visual acuity recovery time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Device main body 2R, 2L Inspection window 11R, 11L Inner cover 14 Light source 15R, 15L Optotype window 20 Optotype presenting part 21 Optotype disc board 24R, 24L LED 25 Dimming circuit 30 Control part

Claims (3)

[Claims] 1. A night vision test in which a target is presented with a dim luminance in a dark visual field after the subject's eye is made photopic, and the night vision or the time until the target can be determined is measured depending on the appearance. Means, and a normal visual acuity inspection means for measuring visual acuity when the visual target is presented in a normal brightness space, using a white LED as the visual target light source, and according to the use of the visual target in each test. A night-time optometer characterized in that a single LED controls at least 10 times or more the brightness by controlling the current to the LED. 2. The night-time optometer according to claim 1, further comprising: an under-glare visual acuity inspection means for presenting an optotype under glare and examining visual acuity according to the appearance thereof; A night vision meter characterized by further changing. 3. The night acuity meter according to claim 1, wherein the LE is set in accordance with a lapse of time measured by the night vision test means.
A night vision machine comprising a control means for variably controlling the brightness of D.