JPH04200524A - Contact lens position correcting device for measuring eyeball movement - Google Patents

Abstract

PURPOSE:To allow the exact measurement of eyeball movement by binarizing the video signals of a television camera, computing the deviation quantity of a contact lens from the coordinates at the two points; the centroid coordinates of the mark of the contact lens and the contour of the pupil by these signals, and correcting the data on the eyeball movement. CONSTITUTION:The contact lens 2 having the dot-shaped mark 2a at the center of the lens is mounted in the prescribed position on the front face of the pupil of the eyeball 1 of a person to be inspected. The video signals of the motion of the eyeball having a gradation from the television camera 3 are inputted to a binarization device 4 when the eyeball movement is photographed by the television camera 3. This device outputs the binary images of the contour of the pupil and the central dot to an arithmetic unit 6. The arithmetic unit 6 successively reads out the binary images and calculate the deviation quantity of the centroid of the mark from the contour of the pupil by determining the contour coordinates at least at the two points; the coordinate of the centroid of the mark and the top, bottom, right or left of the contour of the pupil moving together with the mark when the mark 2 varies its position with the eyeball movement. The data on the eyeball movement is corrected in this way and the correct eyeball movement is displayed even if the deviation rises in the contact lens 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for moving the eyeball in a horizontal, vertical or rotational direction when tracking a visual target presented to a subject for medical diagnosis. When using an eye movement analysis device designed to observe, record, and analyze movement, the eyeballs are photographed with a television camera and the center of the pupil is determined through image processing to measure the eye movement, but the pupil is hidden by the eyelid. When measuring eye movement by attaching a contact lens with a mark to the subject's eyeball and moving the mark in consideration of the situation, even if the contact lens becomes misaligned, the misalignment can be electrically corrected to ensure accurate eye movement. The present invention relates to a position correction device for a contact lens for measuring eye movement, which is capable of measuring changes in the eye movement.

[Conventional technology]

EOG (electro-oculography) is a well-known method for recording eye movements.
) It has also been applied clinically. This involves placing electrodes on the skin around the eyes and recording the potential difference that occurs as the eye moves. Furthermore, a method (PENG) has been disclosed in which eye movement is detected by utilizing the difference in light reflection characteristics between the cornea and sclera of infrared rays irradiated onto the eyeball.

Furthermore, in Japanese Patent Application No. 63-145425, the present applicant previously proposed that a dark room was formed in front of the examinee's eyes, and a cross-shaped cross-shaped structure was installed in the horizontal and vertical directions for examination in a gockle that was equipped with a head mounting means. An optotype consisting of a visible light source is built in, and the lighting of the optotype is switched to cause the subject to be nearsighted, and the eyeball is illuminated with invisible infrared rays, and a video signal of the eye movement is outputted by an infrared detection television camera. We proposed an "eye movement testing device" that can be used to observe, record, and analyze eye movements. .

Furthermore, in Japanese Patent Application No. 63-292930, the present applicant proposed an eye movement analysis device equipped with an optotype for the entire eye movement examination range using light emitting diodes, liquid crystals, etc., and later developed an autofocus system. We have proposed an eye movement analysis device (Japanese Patent Application No. 319322/1983) that is designed to match the focal point of a television camera to the vicinity of the iris of a moving eyeball.

[Invention or problem to be solved]

When using the conventional EOG method or PENG method described above, there are problems such as the need for a dark room during the examination, the need to separately present an optotype, and the inability to examine the rotational movement of the eyeball.
In comparison to these methods, the invention of Japanese Patent Application No. 63-145425 uses goggles worn on the head to form a dark room in front of the examinee's eyes, and an optotype is prepared inside the goggles.
It has unprecedented advantages, such as eliminating the need for a dark room or the need to present separate optotypes during the examination, and allowing the examinee to move while wearing the goggles on their head, making it possible to examine the rotational movement of the eyeballs. There is.

However, in this eye movement analysis device and in the eye movement analysis devices that the applicant has proposed one after another, eye movement is measured by detecting the center of gravity of the pupil. If it comes out completely,
A simple algorithm (calculation formula) has been developed to calculate the center of gravity, and real-time measurement is also possible.If the pupil is hidden when looking upward or downward, calculating the center of gravity of the pupil requires a complicated algorithm, making real-time measurement difficult. There is a problem with becoming.

The applicant should have the subject wear a contact lens with a mark (if the mark is near the center of the contact lens, it will not be hidden by the eyelid, and if there is a small mark, it can be directly calculated as the center of gravity). By detecting that mark, it is possible to measure eye movements, and also,
We have focused on the fact that rotational motion can also be measured by the inclination of the mark in the longitudinal direction of the center, and have been developing this method.

However, when a contact lens with a mark is placed on the eyeball of the examinee and examined, it may shift due to blinking or movement of the eyeball, and in this case, accurate movement of the center of gravity of the mark cannot be determined, There is a problem with errors occurring in the exercise measurement results.

The present invention has been made in view of such changes, and when measuring eye movements by attaching a contact lens with a mark to the eyeball of a subject, the position of the contact lens due to blinking or movement of the eyeball is measured. Regardless of the occurrence of the deviation,
It is an object of the present invention to provide a contact lens position correction device for eye movement measurement that can accurately measure eye movement by always calculating accurate mark barycenter coordinates and obtaining eye movement data.

[Means to solve the problem]

In order to achieve the above object, the contact lens position correction device for measuring eyeball movements of the present invention is equipped with a television camera for photographing the eyeball movements of the subject, and the eyeballs of the subject output from the camera are provided. In order to be used in an eye movement analysis device that observes and records and analyzes eye movements using video signals of movement, contact lenses for measuring eye movements are attached to the subject's eyes, and video signals of eye movements from a television camera are collected. As a device for image processing and correcting eye movement data obtained by changes in the coordinates of the center of gravity of marks attached to contact lenses, it is connected to at least a television camera and binarizes the video signal from the television camera. A binarization device is used to sequentially read out the binary image data of the pupil contour and the contact lens mark obtained by the device, and calculate the deviation of the contact lens from the barycentric coordinates of the mark and the coordinates of at least two points of the pupil contour. an image processing device comprising an arithmetic device that calculates the amount of deviation and corrects the eye movement data obtained from the change in the center of gravity of the mark according to the amount of deviation;
The eye movement is displayed using the output from the image processing device.

The above calculation device sequentially scans the binary image of the pupil outline and the contact lens mark, detects four coordinates on the pupil outline at the maximum and minimum positions in the X direction and the X direction, and calculates the mark barycenter coordinates. From the four coordinates on the pupil contour, calculate the distance between the mark barycenter coordinate and the four coordinates on the pupil contour, and among the calculated distances, find the coordinate with the largest distance in each of the X direction and the X direction, and It is preferable to correct the eye movement data by calculating the difference between the distance from the center of gravity of the mark at the coordinates obtained by scanning as the correction amounts in the X direction and the X direction of the contact lens.

[Effect]

When a marked contact lens with a dot-shaped mark in the center of the lens is attached to a predetermined position in front of the pupil of the subject's eye and eye movements are photographed with a television camera, colored backgrounds such as black backgrounds are detected by the television camera. A gradation video signal of eyeball movement with a dot-shaped mark such as white near the center of the pupil is input to a binarization device, where it is binarized, and a binary image of the pupil outline and the center dot is sent to an arithmetic device. Output.

The arithmetic device sequentially reads out the binary images, and when the mark attached to the contact lens sequentially changes its position along with the eyeball movement to represent the eyeball movement, the calculation device calculates the coordinates of the center of gravity of the mark and the pupil outline that moves with the mark. By determining the contour coordinates of at least two points on the top, bottom, left, and right, the amount of deviation of the center of gravity of the mark from the pupil contour is calculated in sequence, and the eye movement data obtained from the displacement of the center of gravity of the mark is corrected to eliminate the influence of contact lens deviation. By canceling the correction, the correct eye movement signal can be output, and even if the contact lens becomes misaligned due to blinking or eye movement, the correct eye movement signal can always be displayed.

The arithmetic device sequentially scans the binary images of the pupil outline and the contact lens mark recorded in the memory, and detects the coordinates on the pupil outline at the maximum and minimum positions in each of the X and X directions.

Next, distances between the mark barycenter coordinates and the four coordinates on the pupil contour are calculated from the obtained mark barycenter coordinates and the four coordinates of the maximum and minimum positions on the pupil contour. Among the four calculated distances, the coordinates of the larger distance in the X direction and the X direction are determined. Then, the difference between the coordinates obtained in the previous scan and the distances in the X direction and the X direction from the center of gravity of the mark is calculated as the correction amount of the contact lens in the X direction and the X direction, respectively. The eye movement displacement is determined by correcting the eye movement data, which is the current mark center of gravity data, using this correction amount.

〔Example〕

Embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram when eye movement is measured by an eye movement analysis device equipped with a contact lens position correction device for measuring eye movement according to the present invention, and FIG. 2 is a block diagram showing how eye movement is measured using the device. It is a flowchart showing the progress when measuring.

(11 shows the subject's eyeball, and a contact lens (2) for measuring eye movement is attached to the front surface of the cornea.The contact lens (2) has a mark (2) at the center of its front surface.
a), the mark may be formed by dots (point-like) with paint, may be partially raised in the form of dots, and may be clearly binarized by scanning. Good to have.

By wearing this contact lens (2), when measuring eye movement, the mark will not be hidden even if the pupil is hidden when looking up or down, so the mark can be placed near the center of the contact lens. Since the center of gravity of the mark is directly calculated, eye movement can be measured by detecting the movement of the mark. The TV camera (3) receives reflected light from the eyeball surface illuminated using natural light, visible light, or invisible infrared rays and outputs a video signal, and the video signal is transmitted to a binarization device (4), The image is input to an image processing device (7) consisting of a memory (5) and an arithmetic device (6), and the gradated eyeball image of the video signal is binarized by a binarization device (4), and the pupil outline and contact lens are A binary image with the dot-shaped mark (2a) in the center is recorded in the memory (5), and the arithmetic unit (6) reads the memory (5).
The dot data is sequentially read out from the contact lens (2) and the displacement of the contact lens (2) is calculated as described later, and the coordinates of the moving mark are corrected using the displacement to determine the amount of eye movement. The measured eye movements are then displayed on a monitor display (81).

Next, in the computing device (6), the contact lens (2)
A case will be described in which the eye movement displacement is determined by calculating the deviation.

Figure 3 shows a state in which a binary image of a pupil outline and a contact lens mark is stored in a memory where the number of dots in the X direction for image recording is 20 and the number of scanning lines in the X direction is 20. In the model diagram, the pupil contour image (9) and the mark image change their positions on the recording screen as the eyeballs move. FIG. 4 is a flowchart showing a procedure for sequentially reading out dot data (pixel data) from the memory, calculating the displacement of the contact lens, and sequentially calculating the eye movement displacement until the end of the measurement.

First, when scanning the memory image, the distance LX, Ly from the coordinates of the center of gravity of the mark on the contact lens (position coordinates of the mark image αQ) to the pupil contour located at the maximum distance in the X direction and the X direction, since previous sampling has not been performed. m=1. ,
n==1, that is, in the model diagram showing the memory state in Figure 3, a command to start scanning (to find the coordinates of a pixel that changes from ON to OFF) is given (step 12), By scanning in the X direction, the coordinate from ON to OFF can be found (
step +3).

When the X coordinate M and Y coordinate N of the pixel stored in memory as it changes from ON to OFF are obtained (step 14), a command is issued to obtain the coordinates of the next point that changes from ON to OFF (step 15). The next pixel in the direction is scanned (step 16).

On the other hand, if it does not turn from ON to OFF during scanning in the X direction, the next pixel is similarly scanned (step 16). In this way, each pixel in the X direction (1.2.3-
------- Each pixel with a coordinate number of 20) is sequentially scanned in the X direction and the coordinate of the pixel in the X direction (M) of the point that changes from OFF to OFF, the coordinate in the X direction ( N), and when the coordinate of the scanning pixel exceeds the final coordinate (Xm-20) (step 17), the scanning is returned to the original (m=1) and the scanning line is lowered by one (step 18), and the scanning line Scanning is performed sequentially until the last line (Yn=20) is exceeded (step 19), and the X coordinate (M) and X coordinate (N) of the memorized pixel that changes from ON to ON are determined. After completing the scanning in this way, the coordinates (M) of the pupil contour image (9) and mark image α0) in the X direction on the memory are
, X-direction locus I (N), in the next step 20, the X-Y direction (
A command is issued to obtain the X-direction coordinate and the X-direction coordinate of the pixel at the limit (up, down, left and right directions).

That is, in accordance with the command (step 20), in the next step 21, the coordinates M(+) and N(1) of each pixel in the image on the memory are sequentially compared and investigated, or the Set the maximum and minimum initial values of N and M outside the memory recording range, for example, Nm1n=25.
, NmaX= 0, Mmin= 25, Mmax= 0
, and the data detected up to step I9 is
are sequentially scanned, first with the above-mentioned initial value, and then with the coordinates of the previously detected pixel, and the comparison is repeated until the final data is reached (steps 22 and 23).
The numerical values X and y of the coordinates N-M located at the maximum and minimum distances from the initial values in the Y direction (up, down, left and right directions) are determined. (Note that (1) in step 21 refers to ON detected by scanning.
→This is a variable that represents the order of the coordinates that change to OFF. ) In this way, Nm1n: Coordinate of the minimum n line in the X direction
max: Coordinate of maximum n lines in the X direction X2. Y2 (Downward) Mm
in: the minimum m (order of F7) in the X direction) coordinates X3. Yl (left) Mmax: maximum m coordinates in the X direction (in hh order) X4. )'4 Find (right side).

At this time, if the coordinates are detected sequentially in the X direction, or if there are three successive coordinates on the same scanning line in the X direction, the second coordinate X6 in the X direction and the coordinate y in the do.

In Fig. 3, the coordinates of the pixel at the limit position in the X and Y directions determined above are (XI”+2,
Y, = 4), lower in the X direction (X2-12, y2 = 16)
, X direction left: (X3=4), (y3=9), X direction right: (X4=17, y<=9).

Further, the mark coordinates are (XS"10, Ys=IO).

Next, the distance between the pixel at the determined limit position and the mark pixel Lll L2. L- and L4 are obtained for each pixel at the limit position in the X and Y directions (up, down, left and right directions) (step 24).

In the example becomes.

Then, compare the distances t, l, and L2 in the X direction and find the maximum value L
Find Y (step 25). In the example, t, y=force.

Also, the distances in the X direction, L, are compared to find the maximum value LX (step 26). In the embodiment, Lx=5.

Then, the difference between Lxold obtained from the previous sampling and LX obtained from the current scanning is determined as the deviation △X in the X direction, and LYOId obtained from the previous sampling and LY obtained from the current scanning are calculated. Find the difference and set it as the deviation △y in the X direction (
Step 27).

Furthermore, as described above, let X be Lxold at the time of the next scan,
The above LY is set as Lyold at the time of the next scan (step 28).

Then, by correcting the currently detected mark locus ex-y using the above-mentioned ΔX and Δy, new coordinates as the current eye movement displacement can be obtained. (Step 29).

The mark coordinates X fluctuate from moment to moment as described above.

By correcting y by the amount of deviation between the pupil contour coordinates and the mark coordinates at that time, it is possible to obtain a continuous correct movement from the initial mark coordinates, and it is possible to measure the eye movement accurately.

〔Effect of the invention〕

When the contact lens position correction device for eye movement measurement according to the present invention is used in an eye movement analysis device, the following effects can be obtained.

According to the invention described in claim 1, when measuring and analyzing eye movement by detecting the movement of the center of gravity of the pupil, the subject's When measuring eye movement by wearing a contact lens with a mark on the eyeball, the video signal of the eye movement from a television camera is binarized, the deviation between the pupil outline and the contact lens mark is calculated, and the change in the center of gravity of the mark is measured. Since the obtained eye movement data is corrected by the amount of deviation and the eye movement is displayed, correct eye movement can always be measured even if the contact lens is displaced due to blinking or eye movement.

According to the second aspect of the invention, the amount of displacement of the contact lens for correcting the eye movement data is calculated by the calculation device in the X direction and the X direction from the barycentric coordinates of the mark on the binarized pupil contour. We determined the coordinates of large distances, and calculated the difference between the coordinates and the distance in the X and Y directions from the center of gravity of the mark from the previous scan as the amount of contact lens shift, and corrected the eye movement data, so that the eye movement data could be corrected. It is possible to accurately correct the coordinates of the mark's center of gravity to display correct eye movements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram when eye movement is measured using the eye movement analysis device equipped with the contact lens position correction device of the present invention. FIG. 2 is a block diagram when eye movement is measured using the device shown in FIG. 1. 3 is a model diagram showing the binary image recorded in the memory, and FIG. 4 is a flowchart showing the progress of time. FIG. 4 is a flowchart showing the binary image data recorded in the memory, and FIG. 7 is a flowchart showing a procedure for sequentially calculating eye movement displacement until the end of measurement. (1) - Eyeball, (2) Contact lens, (2
a) Mark, (3) Television camera, (4) Binarization device, (5) Memory, (6) Arithmetic device, (
7) Image processing device, (8)-Monitor display,
(9) Binary image of memorized pupil contour, αO
) - binary image of the memorized contact lens mark. Patent applicant Konan Camera Institute Co., Ltd. Patent attorney Fuji 1) Tokihiko (and 1 other person) Procedural amendment January 25, 1991], Case description Uni 1990 Patent Application No. 338599 2, Name of the invention: Contact lens position correction device for eye movement measurement 3; Relationship with the person making the correction: Patent applicant: Konan Camera Institute Co., Ltd. 4; Agent (and 1 other person): 廿 06 (364) 0693■ 5. Claims column, 3, 1.25, and Detailed Description of the Invention column of the specification dated the date of the amendment order. 7. Contents of the amendment (1) The claims section of the specification is amended as follows. r2, Claim 1: A television camera is provided for photographing the eye movements of the subject, and the eye movements are observed, recorded, and analyzed using video signals of the eye movements of the subject output from the camera. In this eye movement analysis device, a contact lens for eye movement measurement is attached to the subject's eyeball, and the video signal from the television camera is image-processed to detect changes in the coordinates of the center of gravity of marks placed on the contact lens. This is a device for correcting the obtained eye movement data, and includes at least a binarization device that is connected to a TV camera and binarizes the video signal from the TV camera, and a signal from the binarization device that corrects the mark. Image processing comprising a calculation device that calculates the amount of displacement of the contact lens from the coordinates of the center of gravity and the coordinates of at least two points on the top, bottom, left, and right of the pupil outline, and corrects the eye movement data obtained from the change in the center of gravity of the mark based on the amount of displacement. 1. A contact lens position correction device for measuring eyeball movement, comprising: a contact lens position correction device for measuring eyeball movement, comprising: a contact lens position correction device for measuring eyeball movement; 2. The arithmetic device sequentially scans the binary image of the pupil outline and the contact lens mark stored in the memory that records the signal from the binarization device, and calculates the coordinates of the center of gravity of the mark and the maximum and minimum in the X and Y directions. A detection means for detecting four coordinates on the pupil contour at a position, and a distance between the mark gravity center coordinate and the four coordinates on the pupil contour from the detected mark gravity center coordinate and the four coordinates on the pupil contour, respectively. means for calculating the coordinates of larger distances in the X and Y directions among the calculated distances, and the difference between the calculated coordinates and the distance in the X and Y directions from the center of gravity of the mark at the coordinates from the previous scan. 2. The contact lens position correction device for eye movement measurement according to claim 1, further comprising means for calculating eye movement displacement as correction amounts in each of the X and Y directions of the contact lens. j(2) In the 9th line of page 4 of the specification, the phrase ``inside the goggle'' is corrected to 1, ``within 1 goggle.'' (3) Add the word "mark barycentric coordinates and j" between "tej" and "X direction/Y direction - j" on page 8, line 16 of the specification. From "Detect the four coordinates on the pupil contour, -" on the 17th line of the page, "Calculate the distance of" on the 20th line, and detect the four coordinates of the mace r@hole contour a calculating means that calculates the distance between the mark barycenter coordinate and the four coordinates on the pupil outline from the detected mark barycenter coordinate and the four coordinates on the pupil outline; (5) Means for determining the coordinates of each large distance by ``calculating'' in the fourth line from ``calculating the coordinates of each large distance'' in the first line of page 9 of the specification; means for calculating the eye movement displacement by calculating the difference between the obtained coordinates and the distance in the X-Y direction from the center of gravity of the mark of the coordinates from the previous scan as a correction amount for each of the X direction and Y direction of the contact lens; Compose and correct the word ``. that's all

Claims (1)

[Claims] 1. A television camera is provided for photographing the eye movements of the subject, and the eye movements are observed, recorded, and analyzed using video signals of the eye movements of the subject output from the camera. In this eye movement analysis device, a contact lens for eye movement measurement is attached to the subject's eyeball, and the video signal from the television camera is image-processed to detect changes in the coordinates of the center of gravity of marks placed on the contact lens. This is a device for correcting the obtained eye movement data, and includes at least a binarization device that is connected to a TV camera and binarizes the video signal from the TV camera, and a signal from the binarization device that corrects the mark. Image processing comprising a calculation device that calculates the amount of displacement of the contact lens from the coordinates of the center of gravity and the coordinates of at least two points on the top, bottom, left, and right of the pupil outline, and corrects the eye movement data obtained from the change in the center of gravity of the mark based on the amount of displacement. 1. A contact lens position correction device for measuring eyeball movement, comprising: a contact lens position correction device for measuring eyeball movement, comprising: a contact lens position correction device for measuring eyeball movement; 2. The arithmetic device sequentially scans the binary image of the pupil outline and the contact lens mark stored in the memory that records the signal from the binarization device, and calculates the pupil at the maximum and minimum position in each of the X and Y directions. Of the distances calculated by detecting four coordinates on the contour and calculating the distances between the mark gravity center coordinates and the four coordinates on the pupil contour from the mark gravity center coordinates and the four coordinates on the pupil contour, By finding coordinates with large distances in each direction and Y direction, and calculating the difference between the distance of the coordinate in the X and Y directions from the center of gravity of the mark from the previous scan as the correction amount of the contact lens in the X and Y directions. Claim 1 wherein eye movement data is corrected.
The contact lens position correction device for eye movement measurement described above.