JP7241579B2 - optotype presentation device - Google Patents

Description

The present invention relates to a target presenting device that presents a target to an eye to be examined.

2. Description of the Related Art Ophthalmology clinics and optician shops are equipped with optotype presenting devices (also referred to as subjective optometry devices) that present various optotypes to an eye to be examined in order to subjectively test various visual functions of the eye to be examined. In such an optotype presenting apparatus, the optotype chart on the chart board is illuminated from behind with white light emitted from the light source, so that the optotype is separated from the subject's eye by a predetermined examination distance (approximately 5 m). Projection-type devices are known that project onto a screen placed on a wall.

A red-green test (also referred to as a red-green test) for finely adjusting the refractive power of a spectacle lens is known as one of the subjective tests of the visual function of an eye to be examined. In this red-green test, the subject's eye is presented with a red-green test target whose background is divided into green and red.

When a red-green test is performed with a projection type optotype presenting device, a dichroic filter including a red filter and a green filter and an optotype chart on which characters, symbols, etc. are formed are placed under white light emitted from a light source. project the red-green test target onto the screen by placing them in the respective optical paths. Thereby, the red-green test target is presented to the subject's eye.

A red glass filter that transmits red light in the red wavelength region is used as the red filter, and a green glass filter that transmits green light in the green wavelength region is used as the green filter. Note that the colored glass filter creates a specific color by absorbing part of the light in the wavelength range that is transmitted and most of the light in the wavelength range that is not transmitted. Therefore, the thickness of the colored glass filter changes the transmittance of light, thereby changing the brightness of the optotype. In addition, since the color glass filter has a relatively large variation in transmittance from member to member, it is necessary to control the thickness of each member in order to obtain the same brightness (performance).

2. Description of the Related Art In recent years, a projection type optotype presenting apparatus often uses a light emitting diode (LED) that emits white light as a light source. At this time, if the red glass filter and the green glass filter used with the conventional halogen lamp are directly illuminated with the white light of the LED, the red background of the red-green test target becomes darker than the green background.

Therefore, in the optotype presenting device described in Patent Literature 1, colored glass filters having different changes in visual characteristics with respect to changes in thickness are used as the red glass filter and the green glass filter. In the optotype presenting device described in Patent Document 1, the thicknesses of the two-color glass filters are adjusted to be the same in order to suppress the generation of shadows at the joined portions of the two-color glass filters, and the red-green test optotypes are used. The thickness of the two-color glass filter is determined so that the visual characteristics of the red background and the green background are substantially the same when presented to the subject's eye. As a result, the red background and the green background of the red-green test target can be presented to the subject's eye with approximately the same brightness.

JP 2008-188058 A

FIG. 13 is an explanatory diagram for explaining a problem of the optotype presenting device described in Patent Document 1. FIG. FIG. 14 is a schematic diagram of a red-green test target 14 presented to the subject's eye by the target presentation device described in Patent Document 1. As shown in FIG.

As shown in FIG. 13, the optotype presenting apparatus of Patent Document 1 uses LEDs (not shown) to illuminate a predetermined optotype chart 102 on a chart plate 100 and a predetermined mask opening 106 on a mask plate 104 during a red-green test. is placed in the optical path of the white light L1 emitted from the . A green glass filter 108 and a red glass filter 109 are provided in this mask opening 106 . Note that the green glass filter 108 and the red glass filter 109 may be provided on the optotype chart 102 .

The green glass filter 108 transmits the green light LG in the green wavelength range of the white light L1. Also, the red glass filter 109 transmits red light LR in the red wavelength region of the white light L1. Then, the target luminous flux L2 composed of the green light LG and the red light LR transmitted through the target chart 102 is imaged on a screen (not shown), and as shown in FIG. , a black object 16B, a green background 16G, and a red background 16R.

At this time, the green glass filter 108 and the red glass filter 109 have thickness. Therefore, even if the green glass filter 108 and the red glass filter 109 have the same thickness, as indicated by the arrow A in FIG. Part of the light L1 is transmitted through one and then through the other. In this case, the mixture of the green light LG and the red light LR produces a shadow 114 on the boundary between the green background 16G and the red background 16R of the red-green test target 14, as shown in FIG.

The shadow 114 described above also occurs when there is a chip in the joint portion (hereinafter abbreviated as joint portion) of the green glass filter 108 and the red glass filter 109 . Even if the joining portion is chamfered to prevent this chipping, a shadow 114 is generated by the chamfered surface. For this reason, there is a method of forming a black line at the junction so that the shadow 114 cannot be seen by the examinee, or polishing the junction after the junction. Since the distance from the red target is large, it becomes difficult for the examinee to compare both targets. Further, the latter method requires polishing after bonding the green glass filter 108 and the red glass filter 109 together, which is very time-consuming.

Furthermore, the green glass filter 108 and the red glass filter 109 should be selected from mass-produced commercial products. For this reason, there is also the problem that the optimum colored glass filter corresponding to the type of light source cannot always be selected. Furthermore, if the thick green glass filter 108 and red glass filter 109 are provided on the mask plate 104 (the chart plate 100 may also be used), the weight of the mask plate 104 increases and the balance is lost, making it difficult to rotate and stop at high speed. Become. As a result, it takes time to switch the target.

Therefore, it is conceivable to use a green dichroic filter that transmits green light and a red dichroic filter that transmits red light instead of the colored glass filters. Since each dichroic filter is a thin film made of a dielectric multilayer film and has a high degree of freedom in designing transmission performance, the problem of the invention according to Patent Document 1 can be solved.

However, each dichroic filter reflects excess light in wavelength ranges other than the wavelength range transmitted in the white light L1. Therefore, the surplus light reflected by each dichroic filter goes back along the optical path of the white light L1 and enters the light source. As a result, there arises a new problem that the excess light reflected by the dichroic filter may adversely affect the light source.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optotype presenting apparatus capable of preventing the excess light reflected by the dichroic filter from adversely affecting the light source.

An optotype presenting device for achieving the object of the present invention comprises a light source for emitting white light, an optotype chart arranged in the optical path of the white light, and a dichroic filter arranged in the optical path, wherein the green wavelength a green dichroic filter that transmits green light in the wavelength range and reflects excess light in other wavelength ranges; and a red dichroic filter that transmits red light in the red wavelength range and reflects excess light in other wavelength ranges. and a dichroic filter, wherein the green dichroic filter and the red dichroic filter are tilted with respect to the optical path.

According to this optotype presenting device, excess light is prevented from entering the light source.

In the optotype presenting device according to another aspect of the present invention, the green dichroic filter and the red dichroic filter reflect excess light to the outside of the optical path. This prevents excess light from entering the light source.

In the optotype presenting device according to another aspect of the present invention, the dichroic filter includes a translucent body having a plurality of inclined planes inclined with respect to the optical path, and the green dichroic filter and the red dichroic filter have different inclined planes. is formed in This prevents excess light from entering the light source.

In the optotype presenting device according to another aspect of the present invention, the dichroic filter includes a translucent body having an inclined surface that is inclined with respect to the optical path, and the green dichroic filter and the red dichroic filter have the same inclined surface with respect to each other. formed in different regions. As a result, excess light is prevented from entering the light source, and the green dichroic filter and the red dichroic filter can be bonded on the inclined surface.

In the optotype presenting device according to another aspect of the present invention, the chart plate rotates about a first rotation axis parallel to the optical path, and a plurality of types of visual stimuli are displayed along the direction around the first rotation axis. a chart board on which a target chart is provided; and a first rotating mechanism for rotating the chart board about a first rotation axis to selectively arrange a plurality of types of target charts in an optical path; A filter is provided at a position corresponding to at least one optotype chart on the chart board. This prevents excess light from entering the light source.

In the optotype presenting device according to another aspect of the present invention, the chart plate rotates about a first rotation axis parallel to the optical path, and a plurality of types of visual stimuli are displayed along the direction around the first rotation axis. a chart plate on which target charts are provided; a first rotating mechanism for rotating the chart plate about a first rotation axis to selectively arrange a plurality of types of target charts in the optical path; a mask plate that rotates about a second rotation axis, the mask plate having a plurality of types of mask openings along the direction around the second rotation axis; and a mask plate about the second rotation axis. and a second rotating mechanism for selectively arranging a plurality of types of mask apertures in the optical path by rotating the dichroic filter at a position corresponding to at least one optotype chart on the chart plate or on the mask plate. It is provided at a position corresponding to at least one mask opening. This prevents excess light from entering the light source.

In the optotype presenting device according to another aspect of the present invention, a light passage plate through which green light and red light that have passed through the dichroic filter pass, and a light blocking member disposed between the dichroic filter and the light passage plate. , wherein the green dichroic filter and the red dichroic filter are set at an inclination angle that causes part of the green light and part of the red light to intersect between the dichroic filter and the light passing plate, and the light shielding member includes two A part of the green light and a part of the red light emitted from the color filter are shielded. This prevents color mixture of green light and red light from occurring between the dichroic filter and the light passage plate, so that a good target can be presented to the subject's eye.

In the optotype presenting device according to another aspect of the present invention, the chart plate rotates about a first rotation axis parallel to the optical path, and a plurality of types of visual stimuli are displayed along the direction around the first rotation axis. a chart board on which a target chart is provided; and a first rotating mechanism for rotating the chart board about a first rotation axis to selectively arrange a plurality of types of target charts in an optical path; The filter is arranged closer to the light source than the chart plate, and the light passage plate is the chart plate. This prevents color mixture of green light and red light from occurring between the dichroic filter and the chart board.

In the optotype presenting device according to another aspect of the present invention, the mask plate rotates around a second rotation axis parallel to the optical path, and a plurality of types of masks are provided along the direction around the second rotation axis. a mask plate provided with openings; and a second rotating mechanism for rotating the mask plate around a second rotation axis to selectively arrange a plurality of types of mask openings in an optical path, wherein the dichroic filter is , is arranged at a position closer to the light source than the mask plate, and the light passing plate is the mask plate. This prevents color mixture of green light and red light from occurring between the dichroic filter and the mask plate.

In the optotype presenting device according to another aspect of the present invention, the light source is a light emitting diode.

The present invention prevents the excess light reflected by the dichroic filter from adversely affecting the light source.

1 is a schematic diagram of an optotype presenting device that selectively presents a plurality of types of optotypes to an eye to be examined; FIG. FIG. 3 is a diagram showing a list of 30 types of optotypes presented to an eye to be examined by an optotype presenting device; It is a front view of a chart board. It is a front view of a mask board. FIG. 2 is an external perspective view of a dichroic filter corresponding to a red-green test target and placed in an optical path; 6 is an explanatory diagram for explaining transmission of green light and red light and reflection of excess light by the dichroic filter shown in FIG. 5; FIG. FIG. 10 is an explanatory diagram for explaining Modification 1 of the dichroic filter corresponding to the red-green test target. FIG. 10 is an explanatory diagram for explaining Modification 2 of the dichroic filter corresponding to the red-green test target. FIG. 11 is an explanatory diagram for explaining Modification 2 of the dichroic filter corresponding to the Worth 4-light test optotype; FIG. 4 is an explanatory diagram for explaining the occurrence of color mixture of green light and red light that have passed through a dichroic filter; FIG. 11 is an explanatory diagram of a target presenting device of Modified Example 3 that can prevent the occurrence of shadows caused by the intersection (color mixture) of green light and red light. FIG. 11 is an explanatory diagram of a target presenting device of Modified Example 4 capable of preventing the generation of shadows caused by the intersection (color mixture) of green light and red light. FIG. 10 is an explanatory diagram for explaining a problem of the optotype presenting device described in Patent Literature 1; 1 is a schematic diagram of a red-green test optotype presented to an eye to be inspected by the optotype presenting device described in Patent Document 1. FIG.

[Configuration of Target Presentation Device]
FIG. 1 is a schematic diagram of an optotype presenting device 10 that selectively presents a plurality of types of optotypes 12 to an eye E to be examined. As shown in FIG. 1, the optotype presenting device 10 is selected by the examiner from among a plurality of types (for example, 30 types in this embodiment) of the optotypes 12 in order to subjectively test various visual functions of the eye E to be examined. By projecting the target 12 on the screen 9, the target 12 is presented to the subject's eye E (subject).

FIG. 2 is a diagram showing a list of 30 types of optotypes 12 presented to the subject's eye E by the optotype presenting device 10. As shown in FIG. The 30 types of optotypes 12 include a black optotype 13 representing black characters or symbols on a white background, and a red-green test optotype 14 and a worthy test optotype 14 having a green and red background or the optotype itself. A four-light test target 15 is included. In this specification, the visual target 12 (black visual target 13, red-green test visual target 14, and Worth 4-light test visual target 15) refers to a visual target image projected on the screen 9, that is, presented to the eye E to be examined. It is a visual target image to be used.

Examples of the black optotype 13 include Landolt rings, symbols, characters, etc. for visual acuity testing, radiographic optotypes for astigmatism testing, point group optotypes for cross-cylinder testing, and anisotropic vision testing. An anisotropy target, a cruciform oblique target for the cruciform oblique test, and a light source target for the Maddox test can be mentioned.

The red-green test optotype 14 is used for the known red-green test, and as shown in FIG. and including. The Worth 4-light test object 15 is used for the known Worth 4-light test and includes a black background 18B, a green object 18G and a red object 18R. The Worth 4-light test (Worth 4-light test index 15) is broadly included in the red-green test (red-green test index 14).

Returning to FIG. 1, the optotype presenting apparatus 10 includes a light source 20, a collimator lens 22, a chart plate 24, a first rotating mechanism 26, a mask plate 28, a second rotating mechanism 30, and a projection lens 32. , a control unit 34 and an operation unit 36 .

The light source 20 is a semiconductor light source that emits white light L1, more specifically an LED (light emitting diode). The symbol OA in the drawing indicates the optical path of the white light L1 (the optical axis of the optical system of the optotype presenting device 10). Also, as the light source 20 that emits the white light L1, a semiconductor light source other than an LED such as a laser diode may be used, or a halogen lamp may be used.

The collimator lens 22 converts the white light L1 emitted from the light source 20 into a parallel light flux (substantially parallel light flux), and then emits the white light L1 toward the mask plate 28 . As a result, the white light L1 passes through the mask opening 29 of the mask plate 28 and the optotype chart 25 of the chart plate 24 in order. Note that the positional relationship between the chart plate 24 and the mask plate 28 may be reversed.

FIG. 3 is a front view of the chart board 24. FIG. As shown in FIG. 3 and FIG. 1 already described, the chart plate 24 is a disk-shaped glass plate that rotates around a first rotation axis 38 parallel to the optical path OA. On this chart board 24, along the direction around the first rotation axis 38 (that is, along the same circle centered on the first rotation axis 38), there are 30 types of targets 12 corresponding to the above-mentioned 30 types of targets 12. Thirty kinds of optotype charts 25 are formed by chromium vapor deposition.

In FIG. 3, in order to prevent complication of the drawing, the optotype charts 25 corresponding to the 30 types of optotypes 12 are simply represented by numbers "1" to "30". For example, the red-green test object 14 is represented by the number "8".

The optotype chart 25 corresponding to each black optotype 13 is obtained by forming a pattern corresponding to each black optotype 13 on a chart plate 24 by chromium vapor deposition. The optotype chart 25 corresponding to the red-green test optotype 14 is obtained by forming a pattern corresponding to the black optotype 16B on the chart plate 24 by chromium vapor deposition. Further, the optotype chart 25 corresponding to the Worth 4-light test optotype 15 is obtained by forming a pattern corresponding to the black background 18B on the chart plate 24 by chromium vapor deposition.

The first rotation axis 38 is provided at a position vertically shifted from the optical path OA so that one of the optotype charts 25 on the chart plate 24 is arranged in the optical path OA. Accordingly, by rotating the chart plate 24 around the first rotation axis 38, one of the 30 types of optotype charts 25 is selectively arranged on the optical path OA.

The first rotating mechanism 26 is composed of a motor (not shown) and a drive transmission mechanism (not shown) that transmits the rotational driving force of this motor to the first rotating shaft 38. , rotates the first rotating shaft 38 . As a result, the chart plate 24 rotates around the first rotation shaft 38 .

FIG. 4 is a front view of the mask plate 28. FIG. As shown in FIG. 4 and FIG. 1 already described, the mask plate 28 is a disk-shaped glass plate that rotates around a second rotation axis 40 parallel to the optical path OA. A light shielding layer 28a (see FIG. 6) is formed on one surface (or both surfaces) of the mask plate 28 by vapor deposition of chromium. In the light shielding layer 28a of the mask plate 28, along the direction around the second rotation axis 40 (that is, along the same circle centered on the second rotation axis 40), a plurality of light shielding layers capable of transmitting the white light L1 are provided. A type of mask opening 29 is formed. The mask plate 28 may be made of a material that does not transmit the white light L1, such as metal.

The plurality of types of mask apertures 29 include, for example, an aperture having a shape that allows the white light L1 to be applied only to a partial region of the optotype chart 25 corresponding to the black optotype 13 for visual acuity testing, and an aperture that allows the entire optotype chart 25 to be illuminated. The region includes openings of various shapes, such as an opening having a shape that can irradiate the white light L1. Thereby, the target chart 25 can be irradiated with the white light L<b>1 within the irradiation range corresponding to the mask opening 29 .

Also, at positions corresponding to the mask openings 29 in part of the mask plate 28, dichroic filters 44 respectively corresponding to the red-green test target 14 and the Worth 4-light test target 15 are provided by a method such as pasting. ing. A dichroic filter 44 corresponding to the red-green test target 14 colors the background of the red-green test target 14 into a green background 16G and a red background 16R. Also, the dichroic filter 44 corresponding to the Worth 4-light test target 15 color-codes the target itself into a green target 18G and a red target 18R.

The second rotating shaft 40 is provided at a position shifted in the above-described vertical direction from the optical path OA so that one of the mask apertures 29 (dichroic filters 44) of the mask plate 28 is arranged in the optical path OA. ing. Accordingly, by rotating the mask plate 28 about the second rotation axis 40, one of the mask apertures 29 (dichroic filters 44) is selectively arranged in the optical path OA.

The second rotating mechanism 30 has the same configuration as the first rotating mechanism 26 described above, and rotates the second rotating shaft 40 under the control of the controller 34, which will be described later. As a result, the mask plate 28 rotates about the second rotating shaft 40 .

Returning to FIG. 1, the control unit 34 rotates each unit (the light source 20, the first rotation mechanism 26, and the second rotation mechanism 30) of the optotype presenting device 10 according to various input operations on the operation unit 36 by the examiner. control the drive of This input operation includes, for example, an on/off operation of the light source 20, a selection operation of the optotype 12, a mask selection operation, and the like.

The control unit 34 turns the light source 20 on and off according to the on/off operation of the light source 20 input to the operation unit 36 .

The control unit 34 drives the first rotating mechanism 26 to rotate the first rotating shaft 38 and the chart plate 24 according to the selection operation of the optotype 12 input to the operation unit 36, thereby responding to the selection operation. The optotype chart 25 is placed on the optical path OA.

Further, when the selection operation input to the operation unit 36 is the selection operation of the black optotype 13, the control unit 34 drives the second rotation mechanism 30 to rotate the second rotation shaft 40 and the mask plate 28. By doing so, the mask aperture 29 capable of irradiating the white light L1 to the entire region of the optotype chart 25 is arranged in the optical path OA. As a result, the white light L1 emitted from the collimator lens 22 passes through the mask opening 29 and the optotype chart 25 in order, and the optotype light flux L2 of the black optotype 13 is emitted from the optotype chart 25. FIG.

On the other hand, when the selection operation input to the operation unit 36 is the selection operation of the red-green test optotype 14 or the Worth 4-light test optotype 15, the control unit 34 drives the second rotating mechanism 30 to rotate the By rotating the two-rotation shaft 40 and the mask plate 28, the dichroic filter 44 corresponding to the selection operation is arranged in the optical path OA. As a result, the white light L1 emitted from the collimator lens 22 passes through the dichroic filter 44 and the optotype chart 25 in order, and the red/green test optotype 14 or the Worth 4-light test optotype 15 is emitted from the optotype chart 25. A target light beam L2 is emitted.

The control unit 34 drives the second rotating mechanism 30 to rotate the second rotating shaft 40 and the mask plate 28 according to the mask operation input to the operation unit 36, thereby opening the mask opening corresponding to the mask selection operation. 29 is placed in the optical path OA. As a result, the irradiation range of the white light L1 irradiated onto the optotype chart 25 is limited by the mask opening 29, so that, for example, the black optotypes 13 for visual acuity testing arranged in a matrix form one vertical line, one horizontal line, and one horizontal line. Alternatively, only one can be selectively presented to the eye E to be examined.

The projection lens 32 forms an image of the optotype luminous flux L2 of the optotype 12 transmitted through the optotype chart 25 on the screen 9 provided at a position separated from the subject's eye E by a predetermined examination distance D (for example, 5 m). Let Thereby, the visual target 12 is presented to the eye E to be examined.

[Dichroic filter]
FIG. 5 is an external perspective view of the dichroic filter 44 corresponding to the red-green test target 14 and placed in the optical path OA. Note that the X direction, Y direction, and Z direction in the drawing are orthogonal to each other. Further, the Z direction is a direction parallel to the optical path OA (optical axis), and in the present embodiment, the white light L1 emitted from the collimator lens 22 is emitted from one Z direction side (−Z direction side) to the other direction side ( +Z direction side).

As shown in FIG. 5 , the dichroic filter 44 includes a transparent body 46 , a green dichroic filter (hereinafter referred to as GDF) 48 and a red dichroic filter (hereinafter referred to as RDF) 49 . In FIG. 5 (similarly to the other drawings), in order to clarify each part of the dichroic filter 44, the thickness ratio of each part is disregarded and the thicknesses of the GDF 48 and RDF 49 are partially exaggerated. Dichroic filters in this specification also include dichroic mirrors.

The transparent body 46 is a glass prism or substrate that can transmit the white light L1. The transparent body 46 is formed by joining a first transparent body 46a and a second transparent body 46b in the shape of a triangular prism extending in the Y direction. The transparent body 46 also has a triangular prism shape extending in the Y direction as a whole and has an isosceles triangular shape (an equilateral triangular shape is also acceptable) when viewed from the Y direction.

The first transparent body 46a and the second transparent body 46b are formed in a line-symmetrical shape with the center of the optical path OA as the axis of symmetry when viewed in the Y direction. The first transparent body 46a is arranged on one side of the X direction (-X direction side), and the second transparent body 46b is arranged on the other side of the X direction (+X direction side). The first transparent body 46a and the second transparent body 46b are joined after forming the GDF 48 and the RDF 49, which will be described later.

Also, the translucent body 46 has three side surfaces parallel to the Y direction. These three side surfaces are a vertical plane 54 forming the base of an isosceles triangle when viewed from the Y direction, and a first inclined plane 55 and a second inclined plane 55 forming two equal sides of the isosceles triangle. a surface 56;

The vertical plane 54 is a plane perpendicular to the Z direction (optical path OA). The vertical surface 54 is composed of two side surfaces, a side surface of the first transparent body 46 a facing the mask plate 28 and a side surface of the second transparent body 46 b facing the mask plate 28 . Thus, the vertical surface 54 is formed by joining the first transparent body 46a and the second transparent body 46b.

The first inclined surface 55 is the side surface of the first transparent body 46a on the side of the collimator lens 22 (the side of the light source 20). The second inclined surface 56 is the side surface of the second transparent body 46b on the side of the collimator lens 22 (the side of the light source 20).

The first inclined surface 55 and the second inclined surface 56 are each inclined with respect to the Z direction (optical path OA). Specifically, the first inclined surface 55 is inclined so as to gradually approach the mask plate 28 side (farther from the collimator lens 22) toward one direction side (−X direction side) in the X direction ( See Figure 6). In addition, the second inclined surface 56 is inclined so as to gradually approach the mask plate 28 side toward the other direction side (+X direction side) in the X direction (see FIG. 6).

The GDF 48 and the RDF 49 are dielectric multilayer films having different refractive indexes, and are formed on different inclined surfaces of the translucent body 46 (on each surface of the first inclined surface 55 and the second inclined surface 56). ) by a known film formation method such as vapor deposition or sputtering. The GDF 48 is formed on the surface of the first slanted surface 55 and the RDF 49 is formed on the surface of the second slanted surface 56 . Therefore, the GDF 48 is inclined with respect to the Z direction (optical path OA) like the first inclined surface 55 and the RDF 49 is inclined with respect to the Z direction (optical path OA) like the second inclined surface 56 .

Also, the GDF 48 and the RDF 49 are joined simultaneously when the first transparent body 46a and the second transparent body 46b are joined together.

FIG. 6 is an explanatory diagram for explaining the transmission of the green light LG and the red light LR by the dichroic filter 44 shown in FIG. 5 and the reflection of the surplus light Lr. As shown in FIG. 6, the dichroic filter 44 has its vertical surface 54 (see FIG. 5) side attached to the mask plate 28 (mask opening 29).

In FIG. 6, the dichroic filter 44 is provided on one side of the mask plate 28 facing the collimator lens 22, but the side opposite to the one side of the mask plate 28 (the side facing the chart plate 24) side). That is, if the dichroic filter 44 is positioned corresponding to the mask opening 29 of the mask plate 28 (position on the optical path of the white light L1 passing through the mask opening 29), the dichroic filter 44 can may be provided in any of the

The GDF 48 transmits only the green light LG in the green wavelength range among the white light L1 incident from the collimator lens 22, and reflects the surplus light Lr in other wavelength ranges. Further, the RDF 49 transmits only the red light LR in the red wavelength range among the white light L1, and reflects the surplus light Lr in other wavelength ranges. As a result, one of the right and left halves of the optotype chart 25 corresponding to the red-green test optotype 14 is illuminated with the green light LG and the other is illuminated with the red light LR, so that the green background 16G and the red background are illuminated. The target luminous flux L2 of the red-green test target 14 color-coded with the background 16R is projected onto the screen 9. FIG.

The green light LG and red light LR are deflected (refracted) by the inclined GDF 48 and RDF 49 to become light non-parallel to the Z direction (optical path OA). In order to prevent complication, the green light LG and the red light LR are represented by light parallel to the Z direction (the same applies to FIG. 8 described later).

Since the GDF 48 and the RDF 49 are inclined with respect to the Z direction (optical path OA), they can reflect the surplus light Lr in the direction toward the outside of the optical path OA (the direction away from the optical path OA). As a result, the surplus light Lr reflected by the GDF 48 and the RDF 49 does not enter the collimator lens 22 and exits out of the optical path OA, or enters the collimator lens 22 and then passes through the collimator lens 22 in a direction different from that of the light source 20. emit toward Therefore, the surplus light Lr is prevented from entering the light source 20 .

Filter characteristics of the GDF 48 and RDF 49 are defined as follows, for example, when the light source 20 is a standard light source (A light source). However, the present invention is not limited to this. The peak of the transmission characteristic of the GDF 48 is within the wavelength range of 530 nm to 550 nm, and the peak of the transmission characteristic of the RDF 49 is within the wavelength range of 600 nm to 620 nm. The full width at half maximum of the spectral luminous transmittance of GDF48 and RDF49 is 60 nm. Furthermore, the spectral luminous transmittances of the GDF 48 and RDF 49 are adjusted so that the lower spectral luminous transmittance does not fall below the higher spectral luminous transmittance of 15%.

Furthermore, the GDF 48 has a spectral transmittance of 0.02 or less at a wavelength of 595 to 605 nm and a spectral transmittance of 0.01 or less at a wavelength of 605 to 700 nm. Further, the RDF 49 has a spectral transmittance of 0.02 or less at a wavelength of 595 to 605 nm and a spectral transmittance of 0.01 or less at a wavelength of 400 to 595 nm.

A dichroic filter 44 corresponding to the Worth 4-light test target 15 emits green light LG toward a position corresponding to the green target 18G in the target chart 25 and to a position corresponding to the red target 18R. emits red light LR. For this reason, the dichroic filter 44 corresponding to the Worth 4-light test target 15 has the positions of the first transparent body 46a and the GDF 48 on the mask plate 28 (mask aperture 29), and the positions of the second transparent body 46b and the RDF 49. Except for the difference in the position of , the configuration is basically the same as that of the dichroic filter 44 corresponding to the red-green test target 14 described above, so detailed description thereof will be omitted.

In the Worth 4-light test target 15, the position of the green target 18G and the position of the red target 18R are separated from each other, so the first transparent body 46a (GDF 48) and the second transparent body 46b (RDF 49) are not necessarily joined together, and both may be separated (see FIG. 9, which will be described later).

As described above, in this embodiment, the GDF48 and the RDF49 are used as the green filter and the red filter of the dichroic filter 44, and by inclining both the GDF48 and the RDF49 with respect to the Z direction (optical path OA), the GDF48 and the RDF49 The excess light Lr reflected by is prevented from entering the light source 20 . As a result, the excess light Lr is prevented from adversely affecting the light source 20 .

Moreover, in this embodiment, by using the GDF 48 and the RDF 49, the thickness can be significantly reduced as compared with the case where the green filter and the red filter are formed of colored glass filters. Therefore, even if the white light L1 obliquely enters the dichroic filter 44 as shown in FIG. As a result, as shown in FIG. 14 described above, the shadow 114 is prevented from being generated at the border between the green background 16G and the red background 16R in the red-green test target 14, which is good for the eye E to be examined. red-green test target 14 can be presented.

Moreover, since the GDF 48 and the RDF 49 are thin films made of dielectric multilayer films, chipping is less likely to occur unlike colored glass filters. Therefore, chipping is less likely to occur at the junction of the GDF 48 and the RDF 49, and shadow 114 is prevented from occurring at the boundary between the green background 16G and the red background 16R. Moreover, it is not necessary to provide a gap between the green background 16G and the red background 16R, or to grind them after the above-described bonding, unlike the conventional art using a colored glass filter. As a result, the good red-green test target 14 and the Worth 4-light test target 15 can be presented to the eye E to be examined, and the labor for polishing can be reduced.

Furthermore, the GDF 48 and RDF 49 have a high degree of freedom in designing transmission performance, unlike commercially available colored glass filters, so that the performance of the GDF 48 and RDF 49 can be optimized according to the type of light source 20 . As a result, the red-green test optotype 14 and the Worth 4-light test optotype 15 can be presented to the eye E to be examined.

Furthermore, since the GDF 48 and RDF 49 are thin films, the weight of the dichroic filter 44 can be significantly reduced as compared with the case of using color glass filters. As a result, the weight increase of the mask plate 104 can be minimized, so that the mask plate 28 can be rotated and stopped at high speed, and the target 12 can be switched in a short time.

[Modification]
A modified example of the dichroic filter 44 (the optotype presenting device 10) will be described below. Since the modified example has basically the same configuration as the above embodiment except for a part, the same reference numerals are given to the same functions or configurations as the above embodiment, and the explanation thereof is omitted. .

<Modification 1>
FIG. 7 is an explanatory diagram for explaining Modification 1 of the dichroic filter 44 corresponding to the red-green test target 14. As shown in FIG. In the above embodiment, the GDF 48 is formed on the first inclined surface 55 of the translucent body 46 and the RDF 49 is formed on the second inclined surface 56. However, as shown in FIG. RDF 49 may be formed. Modification 1 differs from the above-described embodiment in the shape of the transparent body 46 and the formation positions of the GDF 48 and the RDF 49 on the transparent body 46 .

The translucent body 46 of Modification 1 has a triangular prism shape extending in the Y direction, and has an isosceles triangular shape (an equilateral triangular shape is also acceptable) when viewed from the Y direction. The translucent body 46 has a vertical plane 54 parallel to the Y direction and an inclined plane 58 . Here, when the translucent body 46 is viewed from the Y direction, the vertical surface 54 constitutes one of two equilateral triangles, and the inclined surface 58 constitutes the other of the two equilateral triangles.

The vertical surface 54 of Modification 1 is a surface perpendicular to the Z direction (optical path OA) like the vertical surface 54 of the above-described embodiment, and is attached to the mask plate 28 (mask opening 29) of the translucent body 46 .

The inclined surface 58 is inclined in an arbitrary direction with respect to the Z direction (optical path OA), for example, inclined so as to gradually approach the mask plate 28 side (farther from the collimator lens 22) toward the +X direction side. In addition, the inclined surface 58 is divided into two regions S1 and S2 based on the center line C1 parallel to the Y direction.

The GDF 48 and the RDF 49 are formed on different regions S1 and S2 of the same inclined surface 58 by a known film forming method. For example, GDF 48 is formed in region S1 and RDF 49 is formed in region S2. Thereby, the GDF 48 and the RDF 49 are inclined in the same direction with respect to the Z direction (optical path OA). Also in this case, the GDF 48 and the RDF 49 can reflect the surplus light Lr in the direction toward the outside of the optical path OA (the direction away from the optical path OA), so that the same effects as in the above embodiment can be obtained.

In addition, when the GDF 48 and the RDF 49 are formed on the same inclined surface 58 using a film forming method or the like, the GDF 48 and the RDF 49 can be joined on this inclined surface 58, so chipping at the joint portion of the GDF 48 and the RDF 49 can be avoided. is reliably prevented from occurring. Incidentally, in Modification 1, the GDF 48 and the RDF 49 can also be formed for each defined area on the inclined surface 58 .

Modification 1 of the dichroic filter 44 corresponding to the Worth 4-light test target 15 has basically the same configuration as the dichroic filter 44 shown in FIG. 7, so a detailed description thereof will be omitted.

<Modification 2>
FIG. 8 is an explanatory diagram for explaining Modification 2 of the dichroic filter 44 corresponding to the red-green test target 14. As shown in FIG. In the above embodiment, the dichroic filter 44 is provided on the mask plate 28. However, as shown in FIG. It may be provided in a position where In this case as well, the same effects as in the above embodiment can be obtained. The present invention can also be applied to a type of optotype presenting apparatus 10 without the mask plate 28 .

FIG. 9 is an explanatory diagram for explaining Modified Example 2 of the dichroic filter 44 corresponding to the Worth 4-light test target 15. In FIG. As shown in FIG. 9, for the dichroic filter 44 corresponding to the Worth 4-light test target 15, the position of the pattern corresponding to the green target 18G and the position of the pattern corresponding to the red target 18R are separated from each other. Therefore, the first transparent body 46a (GDF 48) and the second transparent body 46b (RDF 49) may be separated. Alternatively, instead of separating the first transparent body 46a and the second transparent body 46b, the first transparent body 46a and the second transparent body 46b are joined together as shown in FIG. may

As the dichroic filter 44 of Modification 2 provided on the chart board 24, instead of the dichroic filter 44 of the embodiment shown in FIGS. 8 and 9, the modification shown in FIG. One dichroic filter 44 may be used.

[Modification 3]
FIG. 10 is an explanatory diagram for explaining the occurrence of color mixture of the green light LG and the red light LR that have passed through the dichroic filter 44 of the above embodiment. In FIG. 10, the green light LG is represented by the area sandwiched by the dotted line arrow, and the red light LR is represented by the area sandwiched by the two-dot chain line arrow (the same applies to FIGS. 11 and 12 described later).

As shown in FIG. 10, the GDF 48 of the above embodiment is inclined so as to gradually approach the mask plate 28 side in the -X direction, and the RDF 49 gradually approaches the mask plate 28 in the +X direction. It is slanted so that Therefore, the green light LG that has passed through the GDF 48 is deflected (refracted) in the +X direction, and the red light LR that has passed through the RDF 49 is deflected (refracted) in the -X direction.

At this time, the GDF 48 and the RDF 49 are set to an inclination angle that causes part of the green light LG and part of the red light LR to intersect between the dichroic filter 44 and the chart plate 24 (optical chart 25). ing. In this case, a portion of the green light LG and a portion of the red light LR intersect (color mix) between the dichroic filter 44 and the chart board 24 to generate a shadow 60 . Therefore, in Modification 3, the generation of the shadow 60 due to the inclination of the GDF 48 and the RDF 49 is prevented.

FIG. 11 is an explanatory diagram of the optotype presenting device 10 of Modification 3 that can prevent the occurrence of the shadow 60 caused by the intersection (color mixture) of the green light LG and the red light LR. As shown in FIG. 11, Modified Example 3 differs from the above embodiment in that a light shielding member 62 is provided. Incidentally, in Modification 3, the chart plate 24 corresponds to the light passage plate of the present invention. 11, the mask plate 28 is provided with the dichroic filter 44 corresponding to the red-green test target 14, but the mask plate 28 is provided with the dichroic filter 44 corresponding to the Worth 4-light test target 15. may have been

The light blocking member 62 is formed on the mask opening 29 of the mask plate 28 or on the vertical surface 54 of the translucent body 46 by chromium vapor deposition, for example. Specifically, the light blocking member 62 is positioned in the mask opening 29 or the vertical plane 54 at a position corresponding to the boundary between the first transparent body 46a and the second transparent body 46b (that is, the boundary between the GDF 48 and the RDF 49). formed. The light shielding member 62 shields light crossing between the dichroic filter 44 and the chart board 24 among the green light LG and the red light LR emitted from the dichroic filter 44 . The position and shape of the light shielding member 62 can be determined through experiments or simulations.

By shielding part of both the green light LG and the red light LR by the light shielding member 62 in this manner, the shadow 60 is prevented from being generated. As a result, the red-green test optotype 14 and the Worth 4-light test optotype 15 can be presented to the eye E to be examined.

[Modification 4]
FIG. 12 is an explanatory diagram of the optotype presenting device 10 of Modification 4 that can prevent the shadow 60 from occurring due to the intersection (color mixture) of the green light LG and the red light LR. As shown in FIG. 12, Modification 4 differs from Modification 3 in the positional relationship between the dichroic filter 44 and the mask plate 28 .

Specifically, in Modification 3 described above, the green light LG and red light LR transmitted through the dichroic filter 44 enter the chart plate 24 , but in Modification 4, the dichroic filter 44 passes through the mask plate 28 is provided at a position close to the light source 20 , and the green light LG and red light LR transmitted through the dichroic filter 44 enter the mask plate 28 . For example, in Modified Example 4, the positional relationship between the mask plate 28 and the chart plate 24 is opposite to that of the above embodiment, and the two-color filter 44 is provided on the chart plate 24 . Therefore, in Modification 4, the mask plate 28 corresponds to the light passage plate of the present invention.

In Modification 4 as well, the light shielding member 62 is formed on the optotype chart 25 of the chart plate 24 or on the vertical surface 54 of the translucent body 46 so that the green light LG and the red light emitted from the dichroic filter 44 are Light crossing between the dichroic filter 44 and the mask plate 28 in the LR may be blocked by the light blocking member 62 . This prevents the shadow 60 from being generated. As a result, the red-green test optotype 14 and the Worth 4-light test optotype 15 can be presented to the eye E to be examined.

[others]
In the above embodiments and modifications, the dichroic filter 44 corresponding to the red-green test target 14 and the Worth 4-light test target 15 is taken as an example, but the background or the target itself is color-coded into green and red. The present invention can also be applied to dichroic filters 44 corresponding to other known visual targets 12 .

In the above embodiments and modifications, an example of the reflection of the surplus light Lr by the GDF 48 and the RDF 49 has been described. It can be changed as appropriate.

Although the transparent body 46 of the above embodiment has two first inclined surfaces 55 and second inclined surfaces 56 as shown in FIGS. , and GDF 48 or RDF 49 may be formed on each inclined surface.

In the above-described embodiment and modified examples, the light-transmitting body 46 of the dichroic filter 44 is formed in a triangular prism shape. If there is, its shape is not particularly limited.

In the above embodiment and modified example, the GDF 48 and the RDF 49 are formed on the transparent body 46 made of glass. GDF 48 and RDF 49 may be formed on light body 46 .

The optotype presenting apparatus 10 of the above-described embodiment and modifications forms (projects) the optotype light flux L2 on the screen 9. For example, an optical system is used to form a virtual image of the optotype 12 based on the optotype light flux L2. is imaged at a position separated from the eye to be examined E by the examination distance D, the present invention can also be applied to a space-saving type optotype presentation device 10 that can be installed at a short distance from the eye to be examined E.

REFERENCE SIGNS LIST 10: optotype presenting device 12: optotype 14: red green test optotype 15: Worth 4-light test optotype 20: light source 24: chart plate 25: optotype chart 26: first rotating mechanism 28: mask plate 29: mask Opening 30 Second rotating mechanism 38 First rotating shaft 40 Second rotating shaft 44 Dichroic filter 46 Transparent body 46a First transparent body 46b Second transparent body 48 Green dichroic filter (GDF )
49 Red dichroic filter (RDF)
54... Vertical surface 55... First inclined surface 56... Second inclined surface 58... Inclined surface 62... Light shielding member

Claims (9)

a light source that emits white light;
an optotype chart positioned in the optical path of the white light;
Dichroic filters arranged in the optical path, comprising a green dichroic filter that transmits green light in the green wavelength range and reflects excess light in other wavelength ranges, and a dichroic filter that transmits red light in the red wavelength range and other a dichroic filter comprising a red dichroic filter that reflects excess light in the wavelength range;
with
the green dichroic filter and the red dichroic filter are tilted with respect to the optical path ;
The optotype presenting device, wherein the green dichroic filter and the red dichroic filter reflect the surplus light to the outside of the optical path. The dichroic filter comprises a transparent body having a plurality of inclined surfaces inclined with respect to the optical path,
2. The optotype presenting device according to claim 1, wherein said green dichroic filter and said red dichroic filter are formed on said different inclined planes. The dichroic filter comprises a transparent body having an inclined surface inclined with respect to the optical path,
2. The optotype presenting device according to claim 1, wherein the green dichroic filter and the red dichroic filter are formed in different regions of the same inclined surface. a chart board that rotates about a first rotation axis parallel to the optical path, the chart board having a plurality of types of the optotype charts provided along a direction around the first rotation axis;
a first rotating mechanism that rotates the chart plate about the first rotation axis to selectively arrange a plurality of types of the optotype charts in the optical path;
with
4. The optotype presenting device according to any one of claims 1 to 3 , wherein the dichroic filter is provided on at least one position of the chart plate corresponding to the optotype chart. a chart board that rotates about a first rotation axis parallel to the optical path, the chart board having a plurality of types of the optotype charts provided along a direction around the first rotation axis;
a first rotating mechanism that rotates the chart plate about the first rotation axis to selectively arrange a plurality of types of the optotype charts in the optical path;
a mask plate that rotates about a second rotation axis parallel to the optical path, the mask plate having a plurality of types of mask openings along a direction around the second rotation axis;
a second rotating mechanism that rotates the mask plate about the second rotation axis to selectively arrange a plurality of types of mask apertures in the optical path;
with
4. The dichroic filter according to any one of claims 1 to 3 , wherein the dichroic filter is provided at a position corresponding to at least one of the optotype charts on the chart plate or at a position corresponding to at least one mask aperture on the mask plate. 2. The optotype presenting device according to item 1. a light passage plate through which the green light and the red light transmitted through the dichroic filter pass;
a light shielding member disposed between the dichroic filter and the light passage plate;
with
the green dichroic filter and the red dichroic filter are set at an inclination angle that causes part of the green light and part of the red light to intersect between the dichroic filter and the light passage plate;
3. The optotype presenting apparatus according to claim 2 , wherein the light shielding member shields part of the green light and part of the red light emitted from the dichroic filter. a chart board that rotates about a first rotation axis parallel to the optical path, the chart board having a plurality of types of the optotype charts provided along a direction around the first rotation axis;
a first rotating mechanism that rotates the chart plate about the first rotation axis to selectively arrange a plurality of types of the optotype charts in the optical path;
with
The dichroic filter is arranged at a position closer to the light source than the chart plate,
7. The optotype presenting device according to claim 6 , wherein the light passage plate is the chart plate. a mask plate that rotates about a second rotation axis parallel to the optical path, the mask plate having a plurality of types of mask openings along a direction around the second rotation axis;
a second rotating mechanism that rotates the mask plate about the second rotation axis to selectively arrange a plurality of types of mask apertures in the optical path;
with
The dichroic filter is arranged at a position closer to the light source than the mask plate,
7. The optotype presenting device according to claim 6 , wherein the light passage plate is the mask plate. 9. The optotype presenting device according to any one of claims 1 to 8 , wherein the light source is a light emitting diode.

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