JP7429561B2 - Visual target presentation device - Google Patents

Description

The present invention relates to an optotype presentation device.

BACKGROUND ART Conventionally, there has been known an optotype presentation device that changes the contrast of an optotype with respect to a background and presents it to a subject when performing a contrast test to determine the contrast sensitivity of an eye to be examined (for example, see Patent Document 1).

JP 2019-136569 Publication

By the way, in conventional optotype presentation devices, optotypes are displayed on a liquid crystal display, but it is known that the brightness of the liquid crystal display generally varies depending on the ambient temperature. In other words, in a typical liquid crystal display, the lower the ambient temperature, the higher the transmittance and the higher the brightness, and the higher the ambient temperature, the lower the transmittance and lower the brightness. Therefore, a problem arises in that the optotype cannot be displayed with a desired contrast depending on the ambient temperature.

The present invention has been made in view of the above problem, and an object of the present invention is to provide an optotype presentation device that can display an optotype with a desired contrast against the background.

In order to achieve the above object, an optotype display device of the present invention is capable of changing a gradation level, and displays an optotype with a predetermined contrast against a background according to the gradation level. and a control section that sets the gradation level and controls the contrast. The control unit obtains the target value of the contrast and the ambient temperature of the optotype display unit, fixes the gradation level of one of the background or the optotype area forming the optotype, and fixes the gradation level of one of the background or the optotype area forming the optotype, and The gradation level of the other of the background or the optotype area is changed to the gradation level determined based on the target value and the ambient temperature.

With the optotype presentation device configured in this manner, the optotype can be displayed with a desired contrast against the background.

1 is an explanatory diagram showing the overall configuration of an optotype presentation device of Example 1. FIG. (a) is a schematic diagram of a visual target shown with a high level of contrast, (b) is a schematic diagram of a visual target shown with a medium level of contrast, and (c) is a schematic diagram of a visual target shown with a low level of contrast. FIG. FIG. 3 is an explanatory diagram of a table that defines the correspondence between contrast and gradation levels divided into predetermined temperature zones. FIG. 3 is an explanatory diagram of a table that defines the basic correspondence between contrast and gradation level, and a table that defines correction values for gradation level set for each temperature zone. FIG. 2 is an explanatory diagram showing the overall configuration of a modified example of the optotype presentation device of Example 1;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the optotype presentation apparatus of this invention is demonstrated based on Example 1 shown in drawing.

(Example 1)
The configuration of the optotype presentation device 10 of Example 1 will be described below based on FIGS. 1 to 3.

The optotype presentation device 10 of Example 1 is a device that displays the optotype to a subject H by appropriately changing the contrast of the optotype with respect to the background, and is used for a contrast test to determine the contrast sensitivity of the eye E to be examined. Here, "contrast" is the ratio of luminance (brightness) between the optotype area 101 forming an optotype (for example, Landolt ring) in the image area 100 and the background 102 (Figs. 2(a) to 2(a)). (c)). The contrast can be determined by the following formula (1).
C(%)=100×(WB)/(W+B)…(1)
Here, C: contrast
B: Luminance (brightness) of optotype area
W: Background luminance (brightness).

As shown in FIGS. 2(a) to 2(c), the visual targets presented differ in appearance due to the difference in contrast. In other words, in the case of a high level of contrast (for example, 100%), as shown in FIG. appear. As the contrast becomes lower, such as medium-level contrast (for example, 50%) and low-level contrast (for example, 25%), the brightness of the optotype area 101 and the background change as shown in FIGS. The ratio with the luminance of 102 becomes small, making it difficult to distinguish the optotype.

As shown in FIG. 1, the optotype presentation device 10 of Example 1 includes a housing 11, an optotype presentation optical system 12, a memory 13, an operation section 14, a temperature sensor 15, a control section 16, It is equipped with

The housing 11 includes a visual target presentation optical system 12, a memory 13, a control unit 16, and the like, and is placed on an optometry table (not shown) or the like. A window portion 11a is formed on the front surface of the housing 11 (on the side of the subject H) for the subject H to visually recognize the optotype.

The optotype presentation optical system 12 includes a display section 12a (optotype display section), a first reflection mirror 12b, a lens 12c, and a second reflection mirror 12d.

Here, the display unit 12a is a liquid crystal display (LCD) that displays arbitrary indicators with a predetermined contrast against the background according to the gradation level. In the optotype presentation optical system 12, the luminous flux from the display unit 12a is reflected by the first reflecting mirror 12b toward the lens 12c, and is refracted by the lens 12c, so that the optotype is displayed at a distance ophthalmological distance from the eye E to be examined. Form a virtual image i. Then, by reflecting the light flux transmitted through the lens 12c by the second reflecting mirror 12d, an optotype is presented at a distance distance in front of the eye E to be examined. The subject H visually recognizes the optotype through the window 11a formed in the housing 11.

The "gradation level" is the number of color density levels that can be displayed on the display unit 12a, and in the first embodiment, it is set to 256 gradations. The display section 12a has a gradation changing function that can change this gradation level. In the display unit 12a, the gradation level of the background 102 in the image area 100 is fixed at 255 gradations, which is the brightest (highest transmittance) state (white), while the optotypes forming the optotype The gradation level of area 101 is changed. This controls the contrast of the optotype with respect to the background 102. In other words, the contrast of the optotype is determined in accordance with the gradation level of the optotype area 101.

Furthermore, the brightness of the display section 12a varies depending on the ambient temperature. That is, the lower the ambient temperature, the higher the transmittance and the brightness of the display section 12a, and the image area 100 tends to become whiter. In addition, the higher the ambient temperature of the display section 12a, the lower the transmittance and the lower the brightness, which tends to make the image area 100 darker. Therefore, even if the gradation level of the optotype region 101 is the same, the contrast of the optotype with respect to the background 102 changes due to the difference in ambient temperature. Note that the "ambient temperature" refers to the ambient temperature around the display section 12a, including the temperature inside the housing 11, the temperature of the circuit board that drives and controls the display section 12a, and the temperature at which the optotype presentation device 10 is installed. Includes environmental (indoor) temperature.

The memory 13 is a storage medium that stores in advance a program for the control unit 16 to execute processing, various information, etc., and also stores various information obtained through the processing of the control unit 16. This memory 13 stores a table (hereinafter referred to as a "contrast-gradation table") that defines the correspondence between the contrast of the optotype with respect to the background 102 and the gradation level of the optotype area 101 for each predetermined temperature range. I remember. That is, in the example shown in Figure 3, the temperature zones are divided into "temperature zone A (18 degrees Celsius to 35 degrees Celsius)," "temperature zone B (below 18 degrees Celsius)," and "temperature zone C (above 35 degrees Celsius)." There is. The temperature zone A is associated with a "contrast-gradation table T1" that defines the correspondence between the contrast of the optotype and the gradation level when the ambient temperature is 18° C. to 35° C. Further, the temperature zone B is associated with a "contrast-gradation table T2" that defines the correspondence between the contrast of the optotype and the gradation level when the ambient temperature is 18° C. or lower. Further, the temperature zone C is associated with a "contrast-gradation table T3" that defines the correspondence between the contrast of the optotype and the gradation level when the ambient temperature is 35° C. or higher. Note that the classification of temperature zones is not limited to the example shown in FIG. 3, and may be set more finely or divided into two stages, a high temperature zone and a low temperature zone.

The operation unit 14 is a user interface operated by the examiner who is the user, and has a function for inputting information and operation instructions. The operation unit 14 includes buttons, keys, control levers provided on the housing 11, and operation devices such as a personal computer or a mobile terminal (mouse, keyboard, trackpad, button, touch panel, etc.) that can communicate with the control unit 16. including. Further, the operation unit 14 may include a processor and a computer program for performing operations and inputs based on voice. Information and operation instructions input via the operation unit 14 are input to the control unit 16.

The temperature sensor 15 is a sensor that detects the ambient temperature of the display section 12a, and is constituted by a thermistor here. Note that a thermistor is an electronic component whose resistance value changes with changes in temperature. Temperature can be detected by measuring the resistance value of a thermistor. The temperature sensor 15 is arranged near the display section 12a inside the housing 11, and detects the ambient temperature around the display section 12a. Further, the temperature sensor 15 may be provided on a circuit board that drives and controls the display section 12a to detect the temperature of this circuit board, or may be provided in a room where the optotype presenting device 10 is set. Room temperature may also be detected. The detected value of the ambient temperature of the display section 12 a detected by the temperature sensor 15 is input to the control section 16 .

The control unit 16 is a calculation device that acquires the target contrast value of the optotype and the ambient temperature of the display unit 12a, and controls the display on the display unit 12a. That is, the target contrast value of the optotype to be presented to the subject H is input to the control unit 16 via the operation unit 14, and the ambient temperature of the display unit 12a detected by the temperature sensor 15 is input. Ru. Further, this control unit 16 can read out information stored in the memory 13 as appropriate. When the control unit 16 obtains the target value of the contrast of the optotype and the ambient temperature, it searches the table stored in the memory 13 based on this target value and the ambient temperature, and matches the contrast of the optotype with the target value. Set the gradation level.

Hereinafter, the operation of the optotype presentation device 10 of Example 1 will be explained.

In the optotype presentation device 10 of the first embodiment, in order to display the optotype with a predetermined contrast against the background 102 and present it to the examinee H, the examiner first responds to the response of the examinee H. The operator operates the operation unit 14 to input a target contrast value of the optotype to be presented to the subject H into the control unit 16.

Subsequently, the temperature sensor 15 detects the ambient temperature of the display section 12a. Note that the detection of the ambient temperature by the temperature sensor 15 may be performed all the time, or may be performed by inputting an instruction via the operation unit 14. The detected value of the ambient temperature of the display section 12 a is input to the control section 16 .

The control unit 16 receives the target value of the contrast of the optotype and the detected value of the ambient temperature, acquires the target value and the ambient temperature, and then uses the acquired ambient temperature to read the contrast-gradation table stored in the memory 13. Determine which of the temperature zones it falls under. That is, when the ambient temperature detected by the temperature sensor 15 is, for example, 25° C., the control unit 16 determines that the temperature zone to which the ambient temperature (25° C.) corresponds is “temperature zone A” in the example shown in FIG. It is determined that

After determining the temperature zone to which the ambient temperature falls, the control unit 16 selects a contrast-gradation table associated with the temperature zone to which it has been determined that the ambient temperature falls. That is, when it is determined that the ambient temperature falls within the "temperature zone A", the control unit 16 selects the "contrast-gradation table T1" in the example shown in FIG. 3.

Then, the control unit 16 determines the gradation level based on the selected contrast-gradation table and the input contrast target value. That is, when the "contrast-gradation table T1" is selected and, for example, 50% is input as the target contrast value, the control unit 16 sets the gradation level to 80 gradations in the example shown in FIG. decide.

After determining the gradation level, the control unit 16 sets the gradation level of the optotype area 101 to the gradation level determined by itself (80 gradations), and displays the optotype on the display unit 12a. Note that at this time, the gradation level of the background 102 is fixed at 255 gradations, which is the brightest state (white). As a result, the contrast of the optotype with respect to the background 102 is 50%.

Next, a case will be described in which the ambient temperature of the display section 12a detected by the temperature sensor 15 is, for example, 10°C.

When the ambient temperature of the display section 12a is 10.degree. C., the display section 12a, which is a liquid crystal display, has a higher transmittance than when the ambient temperature is 25.degree. C., and the brightness of the image area 100 tends to increase.

Here, consider a case where the gradation level of the optotype area 101 is set to the same gradation level (80 gradations) as when the ambient temperature is 25° C. without considering the ambient temperature of the display section 12a. In this case, the brightness of the image region 100 tends to be higher than when the ambient temperature is 25° C., so the optotype region 101 becomes brighter than necessary, making it impossible to obtain 50% contrast.

On the other hand, in the optotype presentation device 10 of the first embodiment, when the control unit 16 determines which of the temperature zones that classify the contrast-gradation table stored in the memory 13 the ambient temperature corresponds to, In the example shown in FIG. 3, it is determined that the temperature zone to which the ambient temperature (10° C.) corresponds is "temperature zone B."

Then, the control unit 16 selects a "contrast-gradation table T2" which is a contrast-gradation table associated with the temperature zone (temperature zone B) to which the ambient temperature (10° C.) corresponds. Next, the control unit 16 determines the gradation level based on the selected "contrast-gradation table T2" and the input contrast target value. That is, when the "contrast-gradation table T2" is selected and, for example, 50% is input as the target contrast value, the gradation level is determined to be 82 gradations in the example shown in FIG. 3.

After determining the gradation level, the control unit 16 sets the gradation level of the optotype area 101 to the gradation level determined by itself (82 gradations), and displays the optotype on the display unit 12a. At this time, the gradation level of the background 102 is fixed at 255 gradations, which is the brightest state (white). As a result, even in an environment where the ambient temperature of the display unit 12a is relatively low and the brightness is high, the gradation level of the optotype area 101 is set to 82 gradations, so that the optotype against the background 102 is can be displayed with a contrast of 50%.

Further, when the ambient temperature of the display unit 12a detected by the temperature sensor 15 is, for example, 40°C, the control unit 16 determines whether the temperature range to which the ambient temperature (40°C) corresponds is It is determined that the temperature is in "temperature zone C."

Then, the control unit 16 selects a "contrast-gradation table T3" which is a contrast-gradation table associated with the temperature zone (temperature zone C) to which the ambient temperature (40° C.) corresponds. Then, the gradation level is determined based on the selected "contrast-gradation table T3" and the input contrast target value (for example, 50%). In the example shown in FIG. 3, the gradation level is determined to be 79 gradations.

Then, the control unit 16 sets the gradation level of the optotype area 101 to the gradation level determined by itself (79 gradations), and then displays the optotype on the display unit 12a. As a result, even in an environment where the ambient temperature of the display unit 12a is relatively high and the brightness is low, the gradation level of the optotype area 101 is set to 79 gradations, so that the optotype against the background 102 is can be displayed with a contrast of 50%.

In this manner, in the optotype presentation device 10 of the first embodiment, the control unit 16 sets the gradation level of the optotype region 101 based on the target contrast value and the ambient temperature of the display unit 12a. Therefore, even if the brightness of the display section 12a varies depending on the ambient temperature, the optotype can be displayed with a desired contrast against the background 102.

Further, in the first embodiment, the memory 13 stores a contrast-gradation table for each predetermined temperature range. After determining the temperature zone to which the ambient temperature falls, the control unit 16 determines the tone level based on the contrast target value and the contrast-gradation table linked to the temperature zone to which the ambient temperature falls. Set. Thereby, accurate gradation levels can be set quickly, and contrast inspection can be carried out smoothly.

Although the optotype presentation device 10 of the present invention has been described above based on the first embodiment, the specific configuration is not limited to this embodiment, and the Changes and additions to the design are permitted as long as they do not depart from the gist of the invention.

In the optotype presentation device 10 of the first embodiment, a contrast-gradation table is stored in the memory 13 for each predetermined temperature zone, and the contrast-gradation table associated with the temperature zone to which the ambient temperature corresponds is used. An example of setting gradation levels was shown. However, it is not limited to this.

As shown in FIG. 4, there is a table (hereinafter referred to as "contrast-gradation basic table Ta") that defines the basic correspondence between the contrast of the optotype with respect to the background 102 and the gradation level of the optotype area 101. , and a table (hereinafter referred to as "correction value table Tb") that defines correction values for gradation levels set in advance for each predetermined temperature range are stored in the memory 13. Then, the control unit 16 calculates the gradation level of the optotype area 101 based on the contrast target value, the contrast-gradation basic table Ta, and the gradation level correction value preset for each temperature zone. may be set.

That is, in this case, after acquiring the target value of contrast and the ambient temperature of the display section 12a, the control section 16 determines whether this ambient temperature is in the temperature range that classifies the correction values in the correction value table Tb stored in the memory 13. Determine which category it corresponds to. Subsequently, the control unit 16 reads out the correction value corresponding to the temperature range determined to correspond to the ambient temperature from the correction value table Tb. Furthermore, the control unit 16 reads out the gradation level (hereinafter referred to as "basic gradation level") corresponding to the input contrast target value from the contrast-gradation basic table Ta stored in the memory 13. Then, the control unit 16 performs a calculation to correct the basic gradation level using the read correction value, and sets the gradation level of the optotype region 101. In this case, accurate gradation levels can be set while suppressing the amount of data stored in the memory 13.

In addition, in the first embodiment, the gradation level of the background 102 is fixed at 255 gradations, which is the brightest state (white), and the gradation level of the optotype area 101 forming the optotype is changed. An example of controlling contrast was shown. However, it is not limited to this. Since it is only necessary to set the contrast of the optotype with respect to the background 102 to a desired contrast, for example, the contrast may be controlled by fixing the gradation level of the optotype area 101 and changing the gradation level of the background 102. . Further, the contrast may be controlled by changing the gradation levels of the optotype region 101 and the background 102, respectively.

Further, in the first embodiment, an example was shown in which the optotype display value 10 includes the temperature sensor 15, but the present invention is not limited to this. For example, as shown in FIG. 5, the control unit 16 may include a temperature acquisition unit 16a that can communicate with an air conditioner 20 installed in a room where the optotype display device 10 is placed. At this time, the control unit 16 uses the temperature acquisition unit 16a to acquire the room temperature (detection value) detected by the temperature sensor 21 (temperature detection device) provided in the air conditioner 20 through communication. Then, when setting the gradation level of the display section 12a, the control section 16 sets the room temperature acquired by the temperature acquisition section 16a as the ambient temperature of the display section 12a.

10 optotype presentation device 11 housing 12 optotype presentation optical system 12a display unit (optotype display unit)
13 Memory 14 Operation unit (target input unit)
15 Temperature sensor (temperature detection section)
16 Control section

Claims (4)

an optotype display unit capable of changing a gradation level and displaying an optotype with a predetermined contrast against a background according to the gradation level;
a control unit that sets the gradation level and controls the contrast,
The control unit acquires the target value of the contrast and the ambient temperature of the optotype display unit, fixes the gradation level of one of the background or an optotype area forming the optotype, and An optotype presentation device, characterized in that the gradation level of the other of the optotype regions is changed to a gradation level determined based on the target value and the ambient temperature. In the optotype presentation device according to claim 1,
comprising a memory storing a table defining a correspondence relationship between the contrast and the gradation level for each predetermined temperature zone;
The control unit determines a temperature zone to which the ambient temperature falls;
selecting from the memory a table linked to the temperature zone to which the ambient temperature is determined to apply;
An optotype presentation device, wherein the gradation level is determined based on the target value and the selected table. In the optotype presentation device according to claim 1,
comprising a memory storing a table defining a basic correspondence relationship between the contrast and the gradation level, and a correction value for the gradation level set for each predetermined temperature zone;
The control unit determines a temperature zone to which the ambient temperature falls;
reading from the memory a correction value for the gradation level associated with the temperature zone to which the ambient temperature is determined to fall;
reading a basic gradation level based on the target value and the table;
An optotype presentation device, wherein the gradation level is determined based on a correction value of the gradation level and the basic gradation level. In the optotype presentation device according to any one of claims 1 to 3,
The optotype presentation device according to claim 1, wherein the control unit includes a temperature acquisition unit that acquires, through communication, a detection value detected by the temperature detection device that detects the ambient temperature.