JPS63222736A - Sight examination apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a method for arranging a plurality of optotypes for measuring visual acuity within one screen and switching between screens having other optotypes for measuring visual acuity. The present invention relates to a visual acuity testing device that can perform visual acuity testing.

[Prior art] To test visual function, visual acuity charts, astigmatism charts,
Since many visual targets such as stereoscopic charts are required, it is practically impossible to fit them all onto one screen due to economical and space constraints.

Therefore, it is common to extract the main visual targets and configure them as one screen, or to divide the entire visual target and have a plurality of visual targets on the same screen. In order to further facilitate the responses of the examiner and the subject, these devices have come to be equipped with a mechanism for specifying what the subject should read from among a plurality of optotypes.

Conventionally, as a means for identifying a certain optotype from among a plurality of optotypes, there has been a method in which a lamp is placed behind each individual optotype and the lamps corresponding to the combination of optotypes to be presented are turned on. However, this device has disadvantages in that the optotype itself is not replaced, so the device becomes large and the subject has to look at the optotype while changing the location of the optotype.

Furthermore, there is known a projection visual acuity testing device (chart projector) that projects an optotype image onto a screen, in which a rotating disc with a mask is superimposed on a rotating disc with an optotype. FIG. 10 is a schematic diagram of this device.

As the visual acuity chart disk 101 rotates about the rotation center 102, the optotype section 103 is switched. The mask plate disk behind the visual acuity chart disk also rotates about 102, so that the horizontal mask 104A overlaps the visual acuity value series shown. Next, when a horizontal mask is superimposed on the visual acuity value row above it, since the horizontal mask 104A is tilted, it is necessary to superimpose another mask, the horizontal mask 104B. In this way, in order to overlay a horizontal mask on each visual acuity value column, a mask is required for each column, and to present one character, a mask is required for each letter.

In this type of projection visual acuity testing device (chart projector), in which a rotating disc with a mask is superimposed on a rotating disc with optotypes, the moving direction of the disc draws an arc, so the center of the screen for all the optotypes. In addition, the number of masks required becomes extremely large, which complicates the equipment.

[Object of the Invention] In view of the above-mentioned drawbacks, the present invention makes it possible to mask all optotypes at the center of the screen and to minimize the number of masks.

[Summary of the Invention] In order to achieve the above object, the present invention arranges a plurality of optotypes for visual acuity measurement in one screen and switches between screens having other optotypes for visual acuity measurement. In a visual acuity testing device capable of It is characterized by the fact that

[Embodiments of the invention] Hereinafter, the present invention will be explained based on drawings of embodiments.

FIG. 1 is an external view of the visual acuity testing apparatus main body according to the first embodiment of the present invention, in which visual targets other than the horizontal row at the center of the screen are masked. FIG. 2 is an external view of the apparatus when the mask roll film 4 is not used for identifying the optotype that the subject should read from a plurality of optotypes on one screen.

Reference numeral 1 is a housing of the apparatus, 2 is an eye chart roll film presented to the subject, and 3 is a light receiving unit for a remote control for switching optotypes by remote control.

The shaded area in FIG. 1 indicates a portion where the light from the lamp 13 is blocked by the mask roll film 4.

3 is a sectional view taken along the line AA in FIG. 2, and FIG. 4 is a sectional view taken along the line B-8' in FIG. 2.

An eye chart roll film 2 on which a visual acuity test target is drawn is wound between an eye chart upper roller 5 and an eye chart lower roller 8, and an eye chart upper motor 16 and an eye chart lower motor 1.
At step 7, the screen is switched by rotating the eye chart upper row 55 and the eye chart lower roller 8. 14A is a photoelectric switch for detecting the initial position of the eye chart roll film located on the left side of the screen, and on the left side of the screen is a charging switch (FIG. 6, 31A) of the same shape for detecting the position of the visual target. Reference numeral 13 denotes a lamp for illuminating the visual acuity chart roll film 2 from the back side, and is turned on by a relay (FIG. 8, 51). 9.12 is a masking upper roller and a masking lower row roller for masking optotypes other than a specific optotype from a plurality of optotypes presented on the screen, and the masking roll film 4 is wound thereon. , an upper mask motor 18, a lower mask motor 24,
Pulley 21.23.29.27 and belt 22.28
The upper roller for the mask 59 and the lower roller for the mask 12
Rotate to switch screens. 14B is a photoelectric switch for detecting the initial position of the mask film placed on the left side of the screen, and a photoelectric switch 31B of the same shape for detecting the position is on the right side of the screen.

5 and 6 are explanatory diagrams of a position detection arrangement for presenting a desired film on the screen.

First, a mark indicating a starting position is written on the visual acuity chart roll film 2 and the mask roll film 4. In this embodiment, since there are black band-shaped marks 30A and 30B at the start position, the position where light is blocked is detected by the photoelectric switch 14A114B for detecting the initial film position.

Next, marks 32A and 32B are written on the visual acuity chart roll film 2 and the mask roll film 4 to indicate the displacement from the starting position for each screen. The mark is detected by the photoelectric switch 31A131B for position detection,
Stop each film at a predetermined position.

FIG. 7 is a diagram for explaining the operation of the mask roll film.

The mask roll film 4 has a rectangular light transmitting portion (horizontal mask) corresponding to one row of optotypes for visual acuity test. This light transmitting part may be a simple opening as long as the strength can be maintained. Further, in this embodiment, as shown in FIG. 3, the mask roll film 4 is placed closer to the lamp than the eye chart roll film 2, but the positional relationship between the two is not important. The explanation is the opposite.

The operation of the embodiment having the above configuration will be described below.

First, the operation for presenting the optotype for visual acuity test will be explained.

When the power is turned on, voltage is not applied to the upper motor 16 of the eye chart so that it can rotate freely, voltage is applied to the lower motor 17 of the eye chart and it is rotated, and the eye chart roll film 2 is moved to the upper eye chart row 58. When the mark 30 is detected by the photoelectric switch 14A for detecting the initial position of the eye chart film, the photoelectric switch 14A is turned off and the eye chart roll film 2 is set at the start position. When the film is stopped, the voltage applied to the upper and lower pulse motors of the eye chart is set below the rated voltage using the voltage switching circuit 48, and the upper and lower rollers of the eye chart are held in a state where no heat is generated to release the film. prevent loosening.

An infrared signal emitted from a remote control 46 outside the device is sent to a light receiving preamplifier 45 and a detection circuit 44 mounted on the housing 1.
, extracts the digitized signal component from the infrared modulated light and sends it to the input/output circuit 43, CPU 40, RAM 41, R
The OM 42 generates a command signal for presenting an optotype corresponding to the signal component. The command signal passes through the input/output circuit 43, and the motor drive circuit 47 and voltage switching circuit 48 maximize the voltage to drive the upper pulse motor 16 of the eye chart. At this time, since no voltage is applied to the lower motor 17 of the sight table, the lower winding row 58 can rotate freely, so high-speed winding is possible despite the small torque of the drive pulse motor.

The feeding position of the visual acuity chart roll film 2 can be detected by the photoelectric switch 31A using the film position detection mark 32A shown in FIG. .

When the driving side motor on the upper side of the eye chart is decelerated, the lower take-up roller 8 rotates freely and the moment of inertia causes the film to be fed out more than necessary. By applying voltage, a weak braking torque is applied. As the speed decreases, the period of the intermittently applied voltage is shortened and stopped.

By the above-described operation, it is possible to prevent the film from loosening even during deceleration and stopping, it is also possible to reduce the tensile force applied to the film, and it is possible to increase the accuracy of the stopping position.

Next, the operation of the mask roll film will be explained.

The method of driving and motor control of the mask roll film 2 is basically the same as that of the eye chart roll film.

That is, when the power is turned on, the lower mask motor 24 rotates, the mask roll film 4 is rewound onto the lower mask roller 12, and the mark 30B is detected by the photoelectric switch 14B for the mask film initial position detection device. , set the mask roll film 4 to the starting position. FIG. 7 shows the direction in which the mask roll film 4 moves. A light-receiving preamplifier 45 attached to the housing 1 receives an infrared signal from an external remote controller 46 instructing a specific visual target row.
, detection circuit 44, input/output circuit 43, CPU 40, RAM
41, generates a command signal for determining the position of the mask corresponding to the signal t, minute through the ROM 42; The command signal is sent to the motor drive circuit 5 via the input/output circuit 43.
2. Maximize the voltage using the voltage switching circuit 53 and drive the upper mask pulse motor 18. At this time, the lower pulse motor 24 for the mask is operated in the same way as the upper motor for the visual acuity chart.
Do not apply voltage to. The feeding position of the mask roll film 4 can be detected by the photoelectric switch 31B using the film position detection mark 32B shown in FIG. . If the upper mask motor on the drive side is decelerated, the lower take-up roller 12 will feed out the film more than necessary, so by intermittently applying a pulsed voltage in the same way as the upper pulse motor of the eye chart, Apply a weak braking torque. As the speed decreases, the period of the intermittently applied voltage is shortened and stopped.

Next, the operation of presenting a specific optotype array on the same screen will be explained.

In FIG. 7, the visual acuity chart roll film 2 is moved to present a predetermined visual acuity surface, and then the mask roll film 4 is moved to place the horizontal mask at the center of the screen. Thereby, only the optotypes 2b in a horizontal row shown in the figure can be presented. Next, when presenting a horizontal row of optotypes 2a, the visual acuity chart film 2 is moved by an unillustrated optotype row changeover switch on the remote controller 46 while keeping the horizontal mask fixed, and the optotypes 2a are presented at the center of the screen. Similarly, when presenting the optotypes 2C in a horizontal row, this is possible by moving the 2G to the center of the screen while keeping the horizontal mask fixed.

As described above, in the first embodiment, it is possible to present all the optotype columns in one horizontal row at the center of the screen using one horizontal mask.

FIG. 9 is a diagram explaining the second embodiment.

The eye chart roll film 2 and the single character presentation mask 4b on the mask roll film 4 are movable in directions orthogonal to each other. The method of driving each film is the same as in the first embodiment, so a description thereof will be omitted. The single character presentation mask 4b is movable in the horizontal direction in the figure, and can be moved to a position that matches the optotype 21 to display only 21. Similarly, 2h, 2j, 2
It is also possible to present the

Moreover, by moving the roll film for a mask in the left-right direction while moving the visual acuity chart film 2d to the position 2h in the figure, it is possible to present 2d to 2g. Similarly, 2e to 20 can also be presented.

In this way, in the second embodiment, all ? by just preparing one character mask. J [One character can be presented for 2d to 20. Furthermore, if a vertical mask is used, all visual targets can be presented in a single vertical line with one vertical mask.

Although the first and second embodiments described above are cases in which a film is used, the same effect can be obtained even if a plate-shaped object is moved for both the eye chart and the mask.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, it is possible to display one horizontal row, one character, and one vertical row using the minimum number of masks. Since the optotypes that are partially displayed with a mask can be presented almost at the center of the screen, the subject does not need to move his or her line of sight during an eye exam, and accurate eye exams can be performed.

[Brief explanation of the drawing]

FIG. 1 is an external view of the visual acuity testing apparatus main body according to an embodiment of the present invention, in which a horizontal mask is used to indicate which optotype the subject should read from a plurality of optotypes on one screen; Figure 2 is an external view of the visual acuity testing device when no mask is used.
Figure 3 is a sectional view in the A-A' force direction of Figure 2, and Figure 4 is a cross-sectional view of Figure 2.
This is a sectional view taken along the line 8--in the figure. 5 and 6 are explanatory diagrams of the position detection mechanism for presenting a desired film on the screen, and FIG. 7 is a diagram for explaining the operation when using a horizontal mask.
FIG. 8 is a block diagram of a drive unit for an acuity chart and a roll film for a mask, FIG. 9 is a diagram for explaining the operation of a single character mask, and FIG. 10 is a schematic diagram of a conventional device. 2... Vision chart roll film 4... Mask roll 14. 31... Photoelectric switch film 1
6... Eye chart upper side (pulse) motor 17... Eye chart lower side (pulse) motor 18... Mask (pulse) upper motor 24... Mask (pulse) lower motor 30... Film expiration position mark 40...C
PU 3rfA- th, Q diagram

Claims (1)

[Claims] 1) Arrange multiple optotypes for visual acuity measurement on one screen,
In a visual acuity testing device capable of switching between screens having other optotypes for visual acuity value measurement, a mask for presenting part of the optotypes within the screen is arranged so as to overlap with the screen, and the A visual acuity testing device characterized in that the mask can be moved in the same direction as or perpendicular to the moving direction of the screen.