JPH04307026A - Visual acuity tester - Google Patents

Abstract

PURPOSE:To achieve a testing smooth by arranging a lighting optical system to light a part of a visual acuity table, a deflection means to deflect a lighting luminous flux and the like to enable accurate indication of an index on the visual acuity table so that a person to be tested can read it. CONSTITUTION:In testing visual acuity, a person to be tested is asked to stand at a position separated at a specified distance from a visual acuity table 10 and a lamp is lit to light the visual acuity table as a whole. Then, one of selection switches of a control panel not illustrated is depressed to select a transmitting section of a mask 4 while a halogen lamp 1 is turned ON. As a result, the illumination light is projected at a specified position of the visual acuity table in the form of a part transmitting it selected. Under such a condition, the person to be tested operates moving switches. As a result, prisms 8a and 8b are turned so as to deflect the illumination light to a position corresponding to the index selected to light a desired target. When the index lit can be read, a switch (YES) of program switches is depressed to make a shift to a next step of the testing.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a visual acuity testing device.
More specifically, the present invention relates to a device that allows a subject to indicate an optotype on an eye chart to be read.

0002

[Prior Art] Various types of visual acuity testing devices are known, but from the viewpoint of the method of forming optotypes, there are two types of visual acuity testing devices: general visual acuity charts printed on paper, etc., and optotypes printed on a rotating disk. It is classified into a projection type visual acuity chart that projects the image on a screen.
In addition, from the viewpoint of illumination method, general visual acuity charts can be classified into types in which the chart is illuminated from the front and types in which the optotype on a milky white or transparent film is illuminated from the back.

0003

[Problem to be Solved by the Invention] Comparing each of these methods with others in terms of price, storage, operation, etc., each method has its advantages and disadvantages, but it is important to note that each method has its own advantages and disadvantages, but it is important to note that the standard visual acuity chart printed on paper, etc. The type of equipment that illuminates from the front is the most popular because it allows for easy testing and the ability to perform testing that closely resembles the everyday visual environment. The problem with this type of device is the difficulty in ensuring proper illumination and in identifying the visual target that the subject should read. In view of the problems of the prior art described above, an object of the present invention is to provide a device that can easily identify visual targets even on a general visual acuity chart printed on paper or the like.

0004

Means for Solving the Problems In order to achieve the above object, the visual acuity testing device of the present invention has the following features. (1) An illumination light source for illuminating a visual acuity chart on which a plurality of optotypes are arranged, an illumination optical system for illuminating a part of the visual acuity chart with a luminous flux from the illumination light source, and a deflection means for deflecting the illumination luminous flux. , an input means for inputting information on the illumination optical system for driving the deflection means and the optotype position of the visual acuity chart, and a storage means for storing the information input to the input means;
It is characterized in that it has a control means for controlling the deflection means based on the information in the storage means, and can selectively present any optotype.

(2) The illumination optical system of (1) has a mask plate or liquid crystal panel having a predetermined mask pattern,
It is characterized in that the mask pattern image is projected onto an eye chart.

(3) The deflection means in (1) is characterized in that it is a prism.

(4) The prism in (3) consists of two prisms with the same number of rotations, and is characterized in that it can be deflected to any position by adjusting the rotation angles of both prisms.

(5) The information stored in the storage means in (1) includes the arrangement of optotypes on the visual acuity chart to be illuminated, the type of aperture pattern of the mask plate, the angle information of the two prism lenses, and the relationship between the visual acuity value and It is characterized by indicating a correspondence relationship.

(6) The storage means in (1) is characterized in that it is rewritable.

0010

[Embodiment 1] This embodiment will be explained below with reference to the drawings. FIG. 1 is an optical layout diagram showing the visual acuity testing device of this embodiment. 1 is a halogen lamp which is a light source for illumination, and 2 is a spherical mirror that reflects the light from the halogen lamp 1. The light from the halogen lamp 1, including the light reflected by the spherical mirror 2, is turned into a parallel beam of light by the condenser lens 3, and is projected onto the mask plate 4. The mask plate 4 has a disc-like shape as shown in FIG. 2, and a light transmitting portion 5 consisting of an opening is formed at a position on the optical path when the mask plate 4 rotates. The shape of the light transmitting part includes a light transmitting part 5A that illuminates one character on the visual acuity chart, a light transmitting part 5B that illuminates a plurality of optotype rows arranged in the horizontal direction, and a plurality of optotype rows arranged in the vertical direction. A light transmitting section 5C that illuminates the astigmatism table, and a light transmitting section 5 that illuminates the astigmatism table.
D, a light transmitting section 5E that illuminates the red-green chart, and a light transmitting section 5F that illuminates the point fixation target. The shape of the light transmitting part can be freely designed according to the configuration of the visual acuity chart described later, and many types of openings can be provided. Alternatively, the visual target to be presented may be simply framed. The mask plate 4 is rotationally driven by a motor 6.

In this embodiment, a mechanism for rotating the mask plate 4 is employed, but the present invention is not limited to this. For example, a liquid crystal panel may be placed on the optical path, and its polarization effect may be used to connect the light transmitting portion to the light blocking portion. By creating parts and combining them, light transmitting parts of various shapes can be created. The light that has passed through the light transmitting section 5 of the mask plate 4 passes through the objective lens 7. The objective lens 7 makes the mask plate 4 and the visual acuity chart 10 conjugate, and projects the image of the light transmitting portion on the mask plate 4 onto the visual acuity chart 10.

[0012] The light passing through the objective lens 7 is incident on a deflection prism 8 composed of two prism lenses 8a and 8b having the same number of degrees. The power of the prism lens is selected in consideration of the size and projection distance of a commercially available projection screen (see the visual acuity chart 10 described below). In this embodiment, when the total of the two prism lenses 8a and 8b is 0 prism, the light transmitting portion 5 of the mask plate 4 is projected approximately at the center of the visual acuity chart. Of the required maximum prism amount determined from the size and projection distance, 1/2 may be set as the power of each prism lens.

The prism lenses 8a and 8b having the same number of rotations are driven to rotate by motors 9a and 9b, respectively, and the light can be deflected to an arbitrary position by controlling each rotation angle in relation to each other. The relationship between the deflection of light and the rotation angle of the prism lenses 8a and 8b will be explained. When two prism lenses of the same frequency are arranged with their base directions opposite to each other, the prism effects mutually cancel each other out. On the other hand, if the base directions are aligned in the same direction, the amount of prism will be doubled. Also, if two prism lenses are rotated in the same direction by an equal amount, the deflection direction can be changed while keeping the deflection angle constant; if two prism lenses are rotated in opposite directions by an equal amount, the deflection direction can be changed. The deflection angle can be changed while keeping constant. in general,
When two lenses having a prism amount p are combined at an angle θ, the total prism amount Δ is given by the following equation.

[Equation 1] The distance from the prism lens 8b to the visual acuity chart 10 is 5 m,
When illuminating a position 50 cm from the center of the visual acuity chart at an angle of 120 degrees, the total prism of the prism lenses 8a and 8b is set to 120 degrees in the base direction and a prism amount of 10Δ. By arbitrarily combining the rotation angles of the prism lenses in this way,
Any location on the visual acuity chart 10 can be brightly illuminated.

Reference numeral 10 denotes a visual acuity chart, which usually has an external shape as shown in FIG. The visual acuity chart 10 includes a general visual acuity chart such as a Landolt ring, a red-green chart, a point cloud chart, and an astigmatism chart. The visual acuity chart may be a commonly used paper chart, but it is better to use one printed on a plastic sheet in view of durability. Further, a high reflectance sheet 10A is attached to the visual acuity chart (at the center of the astigmatism chart or at another position) to serve as a fixation target for the Maddox test.

Reference numeral 11 denotes a halogen lamp which is a light source for illuminating the entire visual acuity chart 10. The halogen lamp 11 illuminates the entire visual acuity chart 10, making it possible to test visual acuity under conditions similar to daily life. The light intensity of the halogen lamps 1 and 11 is adjusted so that the sum of their illumination lights on the visual acuity chart 10 falls within the illuminance standard required for the examination. The output of the lamp is N to accommodate various conditions in the examination room.
It is desirable that the amount of light can be adjusted using a D filter or a dimming circuit. 12 is a spherical mirror that reflects the light from the halogen lamp 11. The light from the halogen lamp 11, including the light reflected by the spherical mirror 12, passes through the condenser lens 13.
It becomes a substantially parallel light beam, and reaches the mask plate 14. The mask plate 14 is provided with a rectangular transparent section consisting of an opening in order to illuminate the entire visual acuity chart 10. The shape of the transparent portion of the mask plate is variable. The objective lens 15 projects the image of the mask plate 14 onto the visual acuity chart 10, and illuminates the entire visual acuity chart 10.

Next, control of the device will be explained. Figure 4
is an external view of the control switch panel of this device. Reference numeral 20 indicates a selection switch group for selecting the transmitting portion 5 of the mask plate 4; 21 indicates a movement switch group for instructing the projection light of the mask plate 4 to move up, down, left and right on the visual acuity chart; and 22 indicates the instruction selection order in advance. A program switch group 23 is used to store and simplify operation, and a print switch 23 is used to print the test results. Program switch group 2
2 serves as a response switch for the examinee and a record switch for the examiner. These switch signals are serial code
It is converted into a coded infrared light pulse signal and sent. Of course, a cable connection type may be used instead of the wireless remote control type operation.

FIG. 5 is a block diagram showing the control circuit of this device. Optical signals emitted from various switches on the control switch panel are received by the light receiving element 30, the carrier signal is removed, and the demodulation circuit 31 demodulates the optical signals into coded signals. It is determined whether the switch has been pressed. When one of the switch groups 20 for selecting the transparent portion 5 of the mask plate 4 is pressed, the mask plate 4
is driven by the motor 6 via the motor drive circuit 33, and the corresponding transmission section is located within the optical path. In addition, when one of the switch groups 21 for instructing the projection light of the mask plate 4 to move up, down, left, and right on the visual acuity chart is pressed, the total prism amount and angle are changed in response to a signal input to the CPU 32. Based on the calculation results, the motors 9a and 9b are driven and controlled via motor drive circuits 34 and 35.

Reference numerals 36 and 37 represent drive circuits for the halogen lamps 1 and 11, which automatically turn off or dim the lamps when they are not operated for a certain period of time, thereby achieving power saving and prolonging the lamp life. 38 is a printer control circuit, 39 is a printer, 40 is a display control circuit, and 41 is a display device. 4
2 is a serial interface for data transfer to external devices such as computers and phoropters. For example, when linked with a phoropter, it facilitates the selection of lenses for the phoropter. Contributes to labor saving. 43
is a non-volatile memory that stores information such as the arrangement of optotypes on the visual acuity chart to be illuminated, the type of aperture pattern of the mask plate, the angle information of the two prism lenses, and the correspondence with visual acuity values.

Regarding the apparatus of the above-described embodiment, first, we will explain the operation of inputting information such as the type of aperture pattern of the mask plate and the angle information of the two prism lenses based on the arrangement of optotypes on the visual acuity chart to be illuminated. explain. FIG. 6 is a flow chart of the operation. First, an input switch (not shown) installed on the control switch side is turned on to switch to input mode. One of the switch groups 20 for selecting the transparent portion of the mask plate 4 is selected. Next, the visual acuity value to be illuminated is inputted using a switch group (not shown), and
After adjusting the image of the transparent part 5 projected on the visual acuity chart to an appropriate position by operating the movement switch group 21, press the memory switch (not shown) to set the image at that position (prism rotation angle) and from the left. Identifiers 1, 2, 1, 2, etc. from above are stored in the nonvolatile memory 43. These operations are repeated in sequence, and after the input is completed, the input switch is turned off to exit the input mode. In this way, the arrangement of the optotypes of the visual acuity chart to be illuminated, the type of aperture pattern of the mask plate, the angle information of the two prism lenses, the correspondence with visual acuity values, etc. are stored in the nonvolatile memory 43. Since the above information can be stored in the nonvolatile memory 43 at any time, the set distance from the visual acuity chart,
Regardless of the type of visual acuity chart, the projection light beam can be moved to the memorized position simply by pressing the up/down/left/right movement switch. Note that the angle information of the prism lens does not only mean obtaining the rotation angle, but may also be information regarding the displacement position that can be calculated based on Equation 1.

Next, an example of an inspection using this apparatus will be explained. When testing the patient's visual acuity, place the patient on the eye chart 10.
Stand at a specified distance from the halogen lamp 1 and turn on the power.
1 is turned on to illuminate the entire visual acuity chart 10. A visual acuity chart with an illumination source can eliminate this process. Next, when one of the selection switches 20 on the control panel is pressed to select the transparent portion of the mask 4, the halogen lamp 1 is turned on. The illumination light projects the shape of the selected transparent portion onto a predetermined position on the visual acuity chart. When the examiner operates the movement switch group 21, the prisms 8a and 8b are each rotated so as to deflect the illumination light to a position corresponding to the selected optotype. In this way, the examiner can illuminate a desired visual target.

When the illuminated optotype can be read, the (Yes) switch of the program switch group 22 is pressed;
Proceed to the next stage of inspection. If the visual acuity cannot be read, the (No) switch is pressed and the test returns to the same visual acuity value or the previous visual acuity level. By repeating such operations, the visual acuity value of the subject is determined. Note that the test subject's visual acuity value can be determined based on criteria (judgment program) such as the highest visual acuity value with the highest correct answer rate above the standard for optotypes with the same visual acuity value, or the visual acuity value of the final test optotype. The test results may be displayed or transmitted to other devices by the determination program.

[0022] Furthermore, the test can be automatically executed using a predetermined program of the apparatus. If the (Yes) switch of the program switch group 22 is pressed when the power is turned on, automatic inspection can be performed according to a predetermined program. Although programs can be designed in a variety of formats,
Finally, the test subject's visual acuity value is determined according to the determination program.

[0023]

[Embodiment 2] In Embodiment 1, the halogen lamps 1 and 11 as illumination light sources were arranged separately, but in Embodiment 2, an example is shown in which both are used in common. FIG. 7 is an optical layout diagram showing only the parts of the structure that are different from the first embodiment, but the same parts are given the same numbers. The upper part of halogen lamp 1 (
(upper figure) is provided with a spherical mirror 12. Spherical mirror 12
The condenser lens 13 converts the light including the light condensed by the condenser lens 13 into a parallel beam of light, which is deflected toward the eye chart by a mirror 45 and used as illumination light to illuminate the entire eye chart.

[0024]

Embodiment 3 FIG. 8 is an optical layout diagram of a device using a visible laser diode. 50 is a laser diode, and the laser light emitted from the laser diode is a flat beam. 51 and 52 are cylindrical lenses that form flat beams into substantially parallel spot shapes. 53a and 53b are prism lenses, and as in the first embodiment, motors 54a and 54b are used to deflect the light beam to an arbitrary position on the visual acuity chart 55.
driven by. When using a laser as an illumination light source, illumination from above the optotype as in Example 1 is
This is not appropriate due to the occurrence of speckles. Therefore, when using laser light, (a) a point image, (b) a line image by continuous horizontal movement, (c) a rectangular image by continuous drive in a rectangular shape, and (d) a continuous drive in a circle. A circular image, etc., is used. A, B, and C can be used to instruct the subject to answer visual acuity values in a horizontal line, and A and D can be used to instruct the subject to answer one letter.

[0025]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, even with a general visual acuity chart printed on paper, etc., the test subject can quickly identify the optotype to be read, so the test can be carried out smoothly. −
It is carried out at

Furthermore, according to the present invention, an existing visual acuity chart can be used with simple input operations without using a dedicated visual acuity chart.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of an optical system in Example 1.

FIG. 2 is an external view of a mask plate.

FIG. 3 is an external view of a general paper optotype.

FIG. 4 is an external view of a control panel switch.

FIG. 5 is a block diagram showing a control circuit.

FIG. 6 is a diagram showing a flowchart of operations.

FIG. 7 is a part of an optical system layout diagram of Example 2.

FIG. 8 is an optical system layout diagram of Example 3.

[Explanation of symbols]

1,11 Halogen light source 4 Mask board 8a, 8b prism lens 10 Visual acuity chart 20 Selection switch group 21　Movement switch group 43 Non-volatile memory

Claims (6)

[Claims] 1. An illumination light source for illuminating a visual acuity chart on which a plurality of optotypes are arranged, an illumination optical system for illuminating a part of the visual acuity chart with a luminous flux from the illumination light source, and a deflector for deflecting the illumination luminous flux. means, input means for inputting information on the illumination optical system for driving the deflection means and the optotype position of the visual acuity chart, storage means for storing the information input to the input means, and storage means for storing the information input to the input means; A visual acuity testing device comprising a control means for controlling the deflection means based on information, and capable of selectively presenting an arbitrary optotype. 2. A visual acuity testing apparatus according to claim 1, wherein the illumination optical system includes a mask plate or a liquid crystal panel having a predetermined mask pattern, and projects an image of the mask pattern onto an eye chart. 3. A visual acuity testing device according to claim 1, wherein the deflection means is a prism. 4. A visual acuity testing device according to claim 3, wherein the prism comprises two prisms having the same number of rotations, and is deflected to an arbitrary position by adjusting the rotation angles of both prisms. 5. The information stored in the storage means of claim 1 includes the correspondence between the optotype arrangement of the visual acuity chart to be illuminated, the type of aperture pattern of the mask plate, the angle information of the two prism lenses, and the visual acuity value. A visual acuity test device characterized in that it shows a relationship. 6. A visual acuity testing device, wherein the storage means according to claim 1 is rewritable.