JPH0588130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an eye refractive power measuring device, and in particular, to an eye refractive power measuring device that can be used to measure the anterior ocular segment image and This invention relates to an improvement in the screen configuration of a measurement target image.

Prior Art A conventional eye refractive power measurement device is configured to project a measurement target image on the fundus of the eye to be examined onto a photocathode of an imaging device, and display the measurement target image based on a video signal from the imaging device. What has been done is known. In addition, as another conventional device, in order to adjust the position of the eye to be examined relative to the device or to monitor the condition of the eye to be examined during measurement, an image of the anterior segment of the eye to be examined is also captured on the same imaging device along with a measurement target image. There is also known a structure in which the images are projected on the same display monitor and these images can be observed on the same display monitor.

Problems to be Solved by the Invention However, in such conventional devices, the measurement target image and the anterior eye segment image are formed by superimposing them on the photocathode of the imaging device, so that they are not displayed on the display monitor. There was a problem in that the boundary between the measurement target image and the anterior segment image was not clear, making it extremely difficult to observe.

In addition, in an automatic eye refractive power measurement device that measures the refractive power of the eye to be examined by detecting the in-focus state of the measurement target image based on the video signal from the imaging device, an anterior segment image is formed on the measurement target image. There is a problem in that if a situation occurs in which the luminous flux overlaps as a flare, it is likely to cause measurement errors.

Therefore, a method of placing an optical mask near the photocathode of the imaging device may be considered, but in such a case, not only would it be difficult to adjust the position of the mask, but it would also be necessary to separate the mask from the photocathode by a predetermined distance. However, the problem remains that the boundary between the measurement target image and the anterior segment image becomes unclear.

Means for Solving the Problems The present invention provides an eye refractive power measurement device configured to display a measurement target image and an anterior segment image on the same display monitor based on an imaging signal from an imaging device. A mask video signal generating means for generating a video signal for masking the area around the measurement target image forming part, and a display monitor that mixes the video signal from the mask video signal generating means and the video signal from the imaging device. The present invention is characterized in that it is provided with a video signal mixing means for outputting to the video signal.

Effect: The area around the measurement target image forming area on the display monitor becomes, for example, a dark, patternless screen, leaving the anterior segment image forming area, and the measurement target image and the anterior segment image can be clearly distinguished and observed.

Embodiments Below, embodiments of the eye refractive power measuring device according to the present invention will be described based on the drawings.

FIG. 1 is a diagram showing an optical system of an eye refractive power measuring device according to the present invention.

In FIG. 1, 1 is a target image projection system;
2 is an imaging optical system, 3 is a shared optical system shared by the target image projection system 1 and the imaging optical system 2, 4 is a chart projection system, 5 is an aiming optical system, 6 is an eye to be examined, and 7 is an anterior eye. Department. The target image projection system 1 is
It has a function of projecting target light onto the fundus 8 of the eye to be examined 6 via the shared optical system 3 to form a target image on the fundus 8, and includes a light emitting element 9,
It is roughly composed of a condenser lens 10, an index plate 11, reflective prisms 12 and 13, a relay lens 14, a reflective prism 15, and a half-moon diaphragm plate 16. Here, the light emitting element 10 emits infrared light, which is invisible light, and this infrared light is converted into a parallel light beam by the condenser lens 10 and is directed to the index plate 1.
Illuminate 1. As shown in FIG. 2, the index plate 11 has slits 11a to 11d formed therein and four deflection prisms 11e to 11h attached thereto. As a result, the index plate 11 is illuminated with infrared light to form a measurement target light, and the deflection prisms 11e to 11h deflect the target light in a direction perpendicular to the longitudinal direction of the slit.

On the other hand, the shared optical system 3 includes a slit prism 1
7, image rotator 18, objective lens 19,
It consists of a beam splitter 20. and,
The target light from the indicator plate 11 is reflected by the reflecting prisms 12, 13, and 15 and passes through the half-moon diaphragm plate 1.
6, passing through the meniscal foramen 16a and 16b,
It is reflected by the reflective surface 17a of the slit prism 17, and then passes through the image rotator 18, objective lens 19, and beam splitter 20 to the subject's eye 6.
The light passes through the pupil of the eye and is projected onto the fundus 8. The half-moon diaphragm plate 16 is arranged in relation to the objective lens 19 so as to be conjugate with the pupil position of the eye 6 to be examined at an appropriate position, and blocks reflected light harmful to measurement from the anterior segment 7 of the eye 6 to be examined. This allows light to enter the eye 6 to be examined. Also,
The image rotator 18 is connected to the optical axis l of the shared optical system 3.
By rotating by an angle of θ/2 around
The measurement target image formed on the fundus 8 is rotated by an angle θ in the meridian direction of the eye 6 to be examined.

The reflected light of the measurement target image projected onto the fundus 8 is transmitted through a beam splitter 20, an objective lens 19,
The light is guided to the imaging optical system 2 via the slit hole 19a of the slit prism 19, the aperture 21a formed in the center of the aperture diaphragm plate 21, the relay lens 22, and the reflection prism 23. Also,
The aperture diaphragm plate 21 is arranged at a position conjugate with the pupil of the eye 6 to be examined, and is adapted to guide reflected light passing through the center of the pupil to the relay lens 22. Furthermore, the imaging optical system 2 is roughly composed of a reflecting mirror 24, a movable lens 25, a reflecting mirror 26, a half mirror 27, and an imaging lens 28, and it receives the reflected light of the measurement target image formed on the fundus 8. The light is guided to a photocathode 29a of the imaging device 29, and a measurement target image is formed on the photocathode 29a. Here, when the image rotator 18 is rotated by an angle θ/2 around the optical axis l as described above,
The measurement target image is designed to rotate by an angle θ in the rotation direction, but since the reflected light of the measurement target image reflected at the fundus 8 passes through the image rotator 18 again, the rotation direction of the image rotator 18 and The measurement target image is rotated by an angle θ in the opposite direction, and a measurement target image facing a predetermined direction is formed on the photocathode 29a of the imaging device 29, regardless of the rotation of the image rotator 18. ing.

The chart projection system 4 includes a tungsten lamp 30 as a visible light source, a color correction filter 31, a condenser lens 32, a chart plate 33, and a moving lens 3.
4, reflective mirrors 36, 37, relay lens 38,
It is roughly composed of a reflecting mirror 39 and an objective lens 40. Here, the chart plate 33 is illuminated by a tungsten lamp 30 via a condenser lens 31 and a color correction filter 32, and the wavelength of the light emitted from the tungsten lamp 30 is selected by the color correction filter 32, and the wavelength is 400 nm.
Only visible light from 700nm to 700nm is transmitted. A chart 33a as shown in FIG. 3 is formed on this chart board 33, and the light from the chart 33a is guided to a moving lens 34 and a relay lens 38, and a reflecting mirror 36,
The optical path is changed by 37 and 39, and the relay lens 3
8 and an objective lens 40, the beam is guided to a beam splitter 41, and is projected toward the subject's eye 6 via the beam splitter 20. Further, the movable lens 34 is disposed so as to be movable in the direction of its optical axis, and when performing objective measurement, the eye 6 to be examined is made to see far-sighted or cloudy depending on the refractive power of the eye 6 to be examined. It is arranged at such a position that measurement can be performed with the accommodation power of the eye 6 to be examined removed.

Furthermore, the aiming optical system 5 is configured to
is for forming an image on the photocathode 29a of the imaging device 29, and the light beam reflected by the anterior segment 7 is transmitted to the beam splitters 20, 41 and the reflecting mirror 42.
After being reflected by the imaging lens 43, the half mirror 27, and the imaging lens 28, the imaging device 2
An anterior segment image is formed on the photocathode 29a of No.9.

The imaging device 29 is connected to a television monitor 44, and 45 is its display surface. On this display surface 45, an image formed on the photocathode 29a based on a video signal from the imaging device 29 is displayed as a visible image. In FIG. 1, 46 is a measurement target image formed by the imaging optical system 2, 47 is an anterior eye segment image formed by the aiming optical system 2, and 48 is a masking section to be described later.

Here, when the target image 46 displayed on the display surface 45 of the television monitor 44 is in focus on the fundus 8, as shown in _FIG. The distance _l2 between the pair of target images 46b is the same. For example, if the measurement target image is focused in front of the fundus 8, the interval _l1 will be smaller than the interval _l2 as shown in FIG. Assuming that the object is in focus, the distance l ₁ will be larger than the distance l ₂ as shown in FIG.

When objectively measuring refractive power, the index plate 11 is moved so that the distances l ₁ and l ₂ between the measurement target images match, and the eye refractive power is determined by the amount of movement of the index plate 11 at this time. That will happen. In this case, the moving lens 25 is driven integrally with the index plate 11 while maintaining a conjugate relationship.

As a result, when the distance between the measurement target images l ₁ and l ₂ is detected, the CPU calculates the distance difference l ₁ −l ₂ until the distance difference l ₁ −l ₂ becomes 0, that is, the distance between the measurement target images The index plate 11 and the movable lens 25 move together along the optical axis until the position where the lens 46 is focused on the fundus 8. In conjunction with this movement, the chart projection system 4
The movable lens 34 is moved so that the eye 6 to be examined is kept in a foggy state at all times. and,
When the interval difference l ₁ −l ₂ becomes 0, the moved index plate 11
The position of is read, and the refractive power in the 0 ⁰ meridian direction is obtained based on this movement position.

Next, the image rotator 18 rotates, for example, 15 times every 6 ⁰ (direction of the meridian to be measured) while keeping the position of the index plate 11 fixed, and the interval difference l ₁ - l ₂ corresponding to each rotation position is determined. Loaded. here,
The refractive power D in the θ direction is obtained by calculating the sum of the diopter value corresponding to the stop position of the index plate 11 and the diopter value corresponding to the interval difference l ₁ −l ₂ value. The refractive power D〓 has a relationship with the spherical power A, the astigmatic power B, and the visual axis α as shown in the following equation (1).

D〓=A+Bcos(θ−α)……(1) Therefore, based on the refractive power D〓 ₁ to D〓 ₁₅ obtained in each meridian direction (15 meridian directions), the spherical power A and astigmatism are determined by the least squares method. The dioptric power B and the astigmatic axis α are each calculated.

Next, the video signal processing circuit shown in FIG. 7 will be explained. The video signal from the imaging device 29 described above is input to a video signal mixer 51, and this video signal mixer 51 includes a mask video signal generator 52.
and the signals from the measurement system detector 53 are respectively supplied, while the output of the video signal mixer 51 is supplied to the television monitor 44. Here, the mask video signal generator 52 generates a video signal for masking the area around the measurement target image forming area on the television monitor 44, and the measurement system detector 53 generates a video signal from the imaging device 29. It has calculation means for detecting the in-focus state of the measurement target image based on the measurement target image. The size of the mask around the area where the measurement target image is formed is set to a size that indicates an allowable range of flare that does not interfere with detection of the in-focus state of the measurement target image by the measurement system detector 53. Therefore, if a flare is observed inside the mask on the TV monitor 44, this indicates that there is a high possibility that a measurement error will occur, and the examiner can easily determine whether the flare is interfering with measurement or not. can.

Note that calculations and the like by the measurement system detector 72 are performed by the CPU of the microcomputer.

Therefore, as shown in FIG.
The first raster screen 54 based on the video signal obtained from the mask video signal generator 52 has an anterior segment image 47 formed in the upper part and a measurement target image 46 in the lower part. A second raster screen 55 based on the signal has a mask 48a on the top.
A masking portion 48 is formed around the masking portion 48, which is dark and has no pattern. When the video signals forming both raster screens 54 and 55 are combined by the video signal mixer 51, the display surface 45 shown in FIG. 1 is obtained.

Effects of the Invention As described above, according to the present invention, only the area around the formation site of the measurement target image is masked to form a visual boundary between the anterior segment image and the measurement target image on the display monitor. Therefore, both the anterior segment image and the measurement target image can be observed very clearly.

Further, by configuring the mask size to eliminate the influence of flare on the measurement target image, it becomes possible to observe the measurement target image and the anterior segment image more clearly and reliably separately.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the optical system of an automatic eye refractive power measuring device according to the present invention, Fig. 2 is a perspective view of an index plate constituting the optical system, and Fig. 3 is a chart plate constituting the optical system. 4 to 6 are schematic diagrams showing each aspect of the imaging state of the measurement target image formed by the same optical system, and FIG. 7 is a plan view of the image signal from the imaging device shown in FIG. 1. FIG. 8 is a schematic diagram illustrating the process of synthesizing the display surface on the display monitor. 1...Target image projection system, 6...Eye to be examined, 4
6... Measurement target image, 47... Anterior segment image, 2
9...Imaging device, 44...TV monitor, 51
...Video signal mixer, 52...Mask video signal generator, 53...Measurement system detector.

Claims (1)

[Scope of Claims] 1. A projection means for projecting a measurement target image onto the fundus of the eye to be examined, a measurement system for measuring the refractive power of the eye to be examined from the focused state of the measurement target image, and an anterior eye of the eye to be examined. and an imaging optical system for projecting the anterior segment image and the measurement target image onto the photocathode of a single imaging device, and displays the anterior segment image and the measurement target image on the same monitor using signals from the imaging device. In the eye refractive power measurement apparatus configured to be capable of displaying an image on the display monitor, a mask video signal generating means for masking the periphery of the measurement target image forming area on the display monitor, and a video signal from the mask video signal generating means are provided. and a video signal mixing means for mixing the video signal from the imaging device and outputting the mixture to the display monitor. 2. The measurement system has calculation means for detecting the in-focus state of the measurement target image from the video signal from the imaging device, and the size of the mask displayed on the display monitor is calculated by the calculation means from the measurement target image. The eye refractive power measuring device according to claim 1, characterized in that it is configured to indicate an allowable range of flare that does not interfere with detection.