JPH0314449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an eye movement imaging device for nystagmus testing for detecting disorders of the visual organs, vestibule, brain stem, cerebrum, or cerebellum.

Disorders of the visual organs, vestibule, brainstem, cerebrum, or cerebellum cause dizziness and imbalance. In recent years, inspection devices for detecting these defects have been developed.

In other words, the subject is asked to gaze at a slowly or rapidly moving spot light or light stripe pattern on a screen 50cm to 100cm in front of their eyes, and the eye movements are extracted as bioelectrical signals and recorded, analyzed, or image processed. Eye movement imaging devices for nystagmus tests have been developed to perform analysis and diagnosis.

[Prior art]

Conventionally, the eye movement imaging device used in this type of nystagmus test irradiates the eyeball with illumination light from an oblique direction.
Images were captured using a CCD camera and the patient's eye movements were observed on a monitor, or images were processed based on the captured images and analyzed for diagnosis.

In addition, the eye movement imaging device for nystagmus testing developed by the present applicant (Japanese Patent Application No. 63-220336) has a system that uses the optical axis of infrared rays to irradiate the eyeball, the optical axis of the lens of the matrix camera, and the eyeball pointing forward. Calculate the correction by arranging the visual axes of the eyeballs so that they are optically coaxial when looking directly, and using an infrared reflecting mirror and a dichroic mirror that reflects infrared rays and transmits visible light. It was possible to accurately image the movement of the eyeball and pupil without any trouble. Further, the eye movement imaging device used in the nystagmus test calculates the XY coordinates of the center of gravity from the number of pixels when scanning a spot image of eye movement in the horizontal and vertical directions.

In addition, as a device that can track eyeball movements and observe retinal blood vessels and other surroundings, for example,
-288133, or as a visual information analysis device using a so-called eye camera that can analyze eyeball movements in real time and grasp the gaze state and movement information of the eyeballs, for example, Japanese Patent Application Laid-Open No. 126140/1986, etc. There is.

[Problem to be solved by the invention]

However, the above-mentioned Japanese Patent Application Laid-Open No. 63-288133,
In all conventional examples such as JP 60-126140, eye movement is imaged by a CCD and processed as an image. That is, the conventional eye movement imaging device uses a CCD consisting of hundreds of thousands of pixels, which is good for capturing clear images, but the scanning time for one frame is 33.3 msec to 15.1 msec. In contrast, the eyeballs move quickly, at a rate of 4 to 5 msec per degree of vision. In particular, in a nystagmus test, it is tested whether or not the subject's eyes can follow slow to fast moving spotlights.

Therefore, the eyeball image that follows rapid movements cannot accurately tell the progress of the eyeball movement unless the CCD is scanned at a faster scanning speed using a special scanning method. For example, even if a nystagmus test is performed using the conventional apparatus described above, the course of eye movement in response to slow movement of a spot light can be determined, but it is difficult to obtain the course of eye movement in response to rapid movement.

Therefore, the present applicant did not view the spot-like pupil image as an image, but rather regarded it as the center of gravity of the above-mentioned spot-like image (Patent Application No. 1983-
220336). However, since each pixel of the spot-like image is added together and then the average value is taken, it takes time to add each pixel and calculation time. Therefore, there was a problem in reliability against the rapid movement of spot light.

In addition, with conventional eye movement imaging devices, when illuminating the eyeball, the illumination device is not placed on the same axis as the patient's eyeball, but illuminates the eyeball from an oblique direction, so the eyeball image is brought to the center of the camera. It was necessary to adjust the position of the camera and to properly irradiate the pupil with infrared rays. Furthermore, when the eyeball is moved from side to side, the movement height of the pupillary reflection image is not necessarily symmetrical. Therefore, in order to correct this, there was a problem in that complicated correction calculations were required.

In order to solve the above problem, the axis of illumination light onto the eyeball is arranged so that the optical axis of the lens of the matrix camera and the visual axis of the eyeball are optically coaxial.

However, the adjustment device for optical coaxiality is large-scale, and while it is good for basic medical research equipment, it is difficult to miniaturize it for clinical testing equipment used in outpatient treatment. There was a problem.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide an eye movement imaging device for nystagmus testing in which the eyeballs are uniformly illuminated from an oblique direction and the resolution and sensitivity are not degraded.

The present invention is an extremely simple device that can capture the pupil image of eye movement as a movement of a point, and the calculation of the position of the pupil image can be performed in eyeball tests in nystagmus tests without the need for complex image processing. An object of the present invention is to provide a motion imaging device.

The present invention makes it possible to reduce the size of the lens and solid-state image sensor of the matrix camera.
It is an object of the present invention to provide an eye movement imaging device for nystagmus testing in which the resolution of an image on a solid-state image sensor of a camera or the S/N ratio does not deteriorate.

[Means to solve the problem]

FIG. 1 shows a block diagram illustrating the principles of the invention.

In FIG. 1, 1 is an eyeball pupil image former, 2 is a matrix camera composed of, for example, a solid-state image sensor, 3 is a matrix controller, and 4 is a matrix camera.
An XY axis value addition device, 5 indicates a data processing device.

The eyeball pupil image forming device 1 applies a matrix to the eyeball.
A device that irradiates the entire surface with uniform light from approximately the same direction as the optical axis of the camera 2 to form a pupil image.

The matrix camera 2 causes the optical signal reflected from the eyeball pupil image to be imaged as a pupil image on a solid-state image sensor through the lens 17 of the matrix camera 2.

The matrix controller 3 receives a clock signal that controls the solid-state image sensor of the matrix camera 2 and the XY-axis value addition device 4, which will be described later.
An electrical window is applied to the scanning signal of the solid-state imaging device, the output data signal obtained from the solid-state imaging device, and the solid-state imaging element to send out a signal that reduces the number of pixels.

The XY-axis value addition device 4 includes an adder, a counter, and a register for obtaining the center of gravity of the pupil image of the eyeball.

The data processing device 5 uses a computer to calculate the XY coordinate values of the center of gravity of the pupil image, and determines the position of the pupil image.
Output as XY coordinate values.

In this way, the XY coordinate values of the pupil image that follows the rapidly moving spot light are continuously obtained, and by viewing these, the disease of the patient can be diagnosed.

[Effect]

The operation based on the present invention will be explained with reference to FIG. FIG. 2 shows a diagram explaining the principle of the XY coordinate calculation procedure according to the present invention.

In FIG. 2, reference numeral 33 indicates a pupil image taken by the matrix camera 2 using the eyeball pupil image forming device 1.

In the eyeball and pupil image forming device 1, illumination light is uniformly incident on the eyeball, and the light beam of the pupil image enters the solid-state image sensor of the matrix camera 2 by a dichroic mirror and is converted into an electrical signal. In the case of such uniform illumination, the resolution is somewhat inferior compared to the infrared point light source of the eye movement imaging device used in conventional nystagmus tests of this type. However, on the other hand, since no infrared reflecting mirror is used, there is an advantage that the luminous flux of the pupil image 33 that enters the lens of the matrix camera 2 can be fully utilized. Therefore, it is sufficient as a clinical device.

The solid-state image sensor of matrix camera 2 has
Since the window is electrically applied, only a certain range of the solid-state image sensor needs to be effectively scanned. As a result, the scanning time of the solid-state image sensor can be shortened to a time that can accurately capture the course of rapidly moving eyeball movements.

The matrix controller 3 forms and sends out signals for obtaining the center of gravity of the pupil image obtained from the solid-state image sensor. The XY axis value adding device 4 is a second
As shown in the figure, the X-axis values of each pixel in the pupil image 33 of the eyeball are added. The data processing device 5 obtains this added X-axis value every time it performs horizontal scanning, and compares the results. That is, the X-axis value added in the first horizontal scan is S ₁ , the X-axis value added in the second scan is S ₂ , and then S ₃ , S ₄ , etc.
...The X-axis value added by scanning the center O of the pupil image 33
S ₀ and the X-axis value added in the next scan is S ₀₊₁ . Then, the X-axis values S ₁ and S ₂ , S ₂ and S ₃ , S ₃ and S ₄ ...
Compare the size of...

Continuing this comparison, the X-axis value S ₀ added in the scan of the center O of the pupil image 33 is the maximum, and the X-axis value S ₀₊₁ added in the next scan is the X-axis value S ₀ becomes smaller. Therefore, the X-axis value _S0 , which is the center of the pupil image 33, is determined by the computer of the data processing device 5. The X-axis value S ₀ obtained by adding in this way is the X-axis value
By dividing by the total number of pixels obtained _S0 , the X coordinate of the center of gravity of the pupil image 33 can be found.

Further, if the number of times the X-axis is scanned at this time is counted by a counter, this number becomes the Y coordinate.

With such simple calculations, the position of the eyeball movement can be obtained as XY coordinate values, so not only is there no need to perform image correction for eyeball movement, but the eyeball movement can be accurately captured.

〔Example〕

FIG. 3 is a schematic explanatory diagram of an embodiment of the present invention.

Hereinafter, one embodiment of the present invention will be specifically described with reference to FIG.

In FIG. 3, 1 is an eyeball pupil image former, 2 is a matrix camera consisting of, for example, a solid-state image sensor, 3 is a matrix controller, and 4 is a matrix camera.
XY axis value addition device, 5 is a data processing device, 11 is an eyeball, 12 is a pupil, 13 is a visual axis, 14, 14' is an illumination device that emits uniform light, 16 is a device that transmits visible light and reflects illumination light. Reflecting dichroic mirror, 17 is the lens of matrix camera 2, 1
9 is a screen, 21 is an optical axis of the matrix camera lens, 22 is an X counter, 23 is a Y counter, 24 is an X adder, 25 is a pixel number counter,
26 is an X shift register, and after the first value enters the register, when the next value enters the register,
The previous value is shifted into a register. 27 is a Y register, 28 is a pixel number register, 29 is a divider,
30 is a comparator, 31 is a subtracter, and the dotted line indicates a band projected as a light reflection image of the eyeball 11.

The eyeball and pupil image forming device 1 includes illumination devices 14 and 14' that emit uniform light, and a dichroic mirror 1.
6 for forming a pupillary reflection image of the eyeball 11. The light emitted from the illumination devices 14, 14' is irradiated onto the eyeball 11. The light beam from the pupil 12 is bent at right angles by a dichroic mirror 16, focused by a lens 17, and enters the matrix camera 2.

Matrix camera 2 electrically windows out of hundreds of thousands of pixels, for example,
Only 10,000 pixels (100 x 100) are used to reduce scanning time. And pupil 1 due to illumination light
The reflected light of 2 is captured as a pupil image 33 by a solid-state imaging device (not shown) of the matrix camera 2, for example, a CCD.

The matrix controller 3 outputs a data signal DATA when the pupil image 33 is present, a vertical synchronization signal, and a clock signal necessary for X-axis scanning.
CLK, one frame end signal, etc. are sent.

The XY axis value addition device 4 includes an X counter 22, a Y counter 23, an X adder 24, and a pixel number counter 2.
5, an X shift register 26, a Y register 27, and a pixel number register 28.

The X counter 22 counts the clock CLK in accordance with each X-axis scan, and is reset at the end of the X-axis scan. In addition, the X counter 22
is transferred to the X adder 24 by the next clock CLK to prepare for addition.

On the other hand, when the horizontal scanning reaches a pixel in the pupil image 33 (see FIG. 2), that is, the data signal output as one pixel of the pupil image 33 from the not-illustrated CCD of the matrix camera 2 is
The value of "1" is transferred to the X adder 24 and the pixel number counter 25.
Put it in. Due to this "1", the X adder 24
The contents of the X counter 22 are added one after another and input into the X shift register 26.

At the same time, the pixel number counter 25 counts the number of pixels, and the result is entered into the pixel number register 28.

For example, in the case shown in FIG. 4, when pixels for the first X-axis coordinate in the pupil image 33 are added, the pupil image 33 appears from the third scanning line shown in FIG. That is, the pixels of the pupil image 33 in the third scanning line exist only when the X counter 22 counts "5", "6", and "7". Then, the X adder 24 adds these and stores the result "18" in the X shift register 26.

Next, the pixels of the pupil image 33 on the fourth scanning line have the X counter 22 set to "3", "4", "5",
Exists only when counting ``6'', ``7'', ``8'', and ``9''. That is, the X adder 24 is 3+4
+5+6+7+8+9=42 is executed and stored in the X shift register 26. At the same time, "18" that was previously stored is in register 2.
Shift to 6. Similarly, the X adder 24
Then, the following addition is performed.

5th scanning line 2+3+4+5+6+7+8+9+
10=54 6th scanning line 2+3+4+5+6+7+8+9+
10=54 7th scanning line 2+3+4+5+6+7+8+9+
10=54 8th scanning line 1+2+3+4+5+6+7+8+
9+10+11=66 9th scanning line 2+3+4+5+6+7+8+9+
10=54 On the other hand, the comparator 30 compares (subtracts) the value previously entered into the X shift register 26, for example "18", and the value newly entered into the X shift register 26, for example "42". ), and when the comparison result changes from negative to positive, the comparator 30 outputs a one-frame end signal. That is, since the addition result "54" of the ninth scanning line is subtracted from the addition result "66" of the eighth scanning line and becomes "+", a one frame end signal is output.

The number in the pixel number register 28 is sent to the divider 29 by the one frame end signal output from the comparator 30.

In addition, the vertical synchronization signal output every time the X axis is scanned is used to control the X counter 22 and the pixel number counter 25.
At the same time as resetting the Y counter, the Y counter is incremented by 1 and the value is stored in the Y register 27.

Next, in the comparator 30, for example, as shown in FIG. , pixel number register 2
Divide by the number "11" stored in 8 and use this as the X coordinate.

At this time, the Y register 27 contains "9" as the ninth horizontal scanning line. However, since the center of gravity of the pupil image 33 is on the 8th horizontal scanning line, "1" is automatically subtracted by the subtracter 31.
Let this be the Y coordinate.

In this way, the X and Y coordinates are determined as the center of gravity position of the pupil image 33 of one frame, but it is not necessary to perform horizontal scanning to the end.

Since the center of gravity position of the pupil image 33 determined by the present invention is an absolute value, a diagnostic result can be obtained without image correction.

FIG. 5 shows an explanatory diagram of the XY coordinate calculation procedure in another embodiment of the present invention.

Similar to the method shown in FIG. 2, in order to obtain the center of gravity of the pupil image 33, it is necessary to determine the number of horizontal scanning lines that scan the center O of the pupil image 33, the number of pixels of the pupil image 33 at that time, and the number of pixels of the pupil image 33 at that time. All you need to know is the added value.

Therefore, as shown in Figure 5, X ₁ /Y,
X ₂ /Y, X ₃ /Y... In other words, find the differential values of these, and it can be seen that the scanning line when this differential value becomes 0 is the one that passes through the center of the pupil image 33. .

However _, X ₁ = _{S 1} / ₂ , S ₂ is the second
It becomes "42", etc. as shown in the figure.

Therefore, if the scanning line at the center of the pupil image 33 is known, the subsequent calculations can be made from the illustration in FIG.

As shown in Figure 4, if the number of horizontal scanning lines is small, the differential coefficient may be 0, or when divided by 2, it may be a fraction, but in reality there are many horizontal scanning lines. This rarely happens. However, considering the case where noise etc. enter,
It is also possible to increase the number of scan lines to be compared, detect the time point at which the differential coefficient is 0 or the polarity changes continuously, and obtain the center line of the axis from this detected value.

Further, in the embodiments shown in FIGS. 4 and 5, the X coordinate is determined from the value obtained by horizontal scanning, but the X coordinate can also be determined after determining the Y coordinate from the value.

〔Effect of the invention〕

According to the present invention, the center of gravity of the pupil image of the eyeball is set to Y
Since it is calculated as a coordinate position, it is the absolute value of the movement of the eyeball, so there is no need to perform image correction, and accurate diagnosis can be made.

According to the present invention, by electrically windowing the solid-state image sensor of the matrix camera to reduce the number of pixels and further speeding up the scanning time, it has not only been possible to achieve a scanning time of 4 msec, but also to increase the scanning speed of the pupil image. You can do it in about half.

Therefore, even rapid eye movements can be accurately measured.

According to the present invention, since only the center point of the pupil image is calculated, the S/N ratio can be improved regardless of the resolution, and the accuracy of diagnosis can be improved without performing image correction. be able to.

According to the present invention, since there is no need to provide an infrared reflecting mirror, it is possible to downsize the apparatus and reduce the number of adjustment parts, making it possible to provide an inexpensive apparatus for clinicians.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a diagram explaining the principle of the XY coordinate calculation procedure in the present invention, FIG. Calculation procedure explanatory diagram,
FIG. 5 shows an explanatory diagram of the XY coordinate calculation procedure in another embodiment of the present invention. In the figure, 1... eyeball pupil image former, 2...
Matrix camera, 3... Matrix controller, 4... XY axis value addition device, 5... Data processing device, 11... Eyeball, 12... Pupil, 1
3...Visual axis, 14...Uniform illumination, 16...Dichroic mirror, 17...Lens, 19...Screen, 21...Optical axis of lens, 22...X counter, 23...Y counter, 24 ...X adder,
25... Pixel number counter, 26... X shift register, 27... Y register, 28... Pixel number register, 29... Divider, 30... Comparator, 31...
Subtractor, 33...Pupillary image.

Claims (1)

[Claims] 1. An eye movement imaging device for nystagmus testing that images the eye movement when the eyeball follows the rapid movement of a light source projected on a screen, comprising: a matrix camera 2 equipped with a solid-state image sensor that captures the pupil image formed by the eyeball pupil image former 1 and extracts it as an analog signal for each pixel; and the matrix camera. A scanning clock signal for scanning the image sensor 2, a clock signal for processing the pupil image into position information of X-axis coordinates and Y-axis coordinates, a frame enable signal issued for each frame, and a solid-state imaging device for matrix camera 2. a matrix controller 3 that sends out a data signal obtained by scanning a pixel of the solid-state image sensor, and a signal that applies an electrical window to reduce the effective scanning area for the pixels of the solid-state image sensor; Each pixel of the pupil image obtained from each transmission signal is
The XY-axis value addition device 4 that adds up the axis values is compared with the total number of pixels for each horizontal scanning line added by the XY-axis value addition device 4, and the sum of the largest number of pixels in the horizontal scanning line is calculated. an eyeball in a nystagmus test, comprising: a data processing device 5 that calculates dividing by the number of pixels at that time to set the X-axis coordinate and the number of horizontal scanning lines at that time to set the Y-axis coordinate; Movement imaging device. 2. The eye movement imaging device for nystagmus testing according to claim 1, wherein the light irradiated onto the eyeball 11 in the eyeball pupil image forming device 1 is uniform illumination. 3 The XY-axis value addition device 4 and the data processing device 5 determine the centroid value of the X-axis value or Y-axis value by determining the differential coefficient of the X-axis value or Y-axis value obtained by scanning the pupil image. The eye movement imaging device for nystagmus testing according to claim 1, wherein the apparatus calculates and outputs the calculated result as an XY coordinate signal.