JPS5822026A - Pupil meter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pupillometer, and in particular, an object of the present invention is to provide a pupillometer having a function of detecting the position of the pupil.

For example, a pupillometer that measures the diameter and area of the pupil from the video signal while photographing the anterior segment of the eye with a television camera is published in Japanese Patent Publication No. 51-29360.

Special Publication No. 52-28316 and Special Publication No. 52-2.83
No. 17, etc., and is publicly known.

However, these conventional pupillometers cannot detect the position of the pupil or measure the movement of the eyeball.

It is an object of the present invention to provide a pupillometer capable of obtaining data not only on the diameter and area of the pupil, but also on the position of the center of the pupil.

Another object of the invention is to digitally process video signals to achieve the above objectives.

The present invention will be described in detail below with reference to the drawings.

Referring to FIG. 1 showing an overall system diagram of an embodiment of the present invention, video signals obtained by left and right imagers IL and IR pass through process amplifiers 2L and 2R, respectively, to level detectors 3L and 2R. Given to 3R.

Here, the signal of the pupil part, which is the black level, is convolved based on the level difference between the signals indicating the pupil part and the iris part of the video signal. The pupillary signal obtained in this way is as follows.

The light is applied to the detection devices 4L and 4R, where the diameter area 9 position of the pupil is detected. The data obtained in this way is given to the data processing unit 6 via the buffer 5, where it processes necessary items such as the pupil area during light stimulation and the change in pupil area based on the light stimulation, and the results are sent to a digital printer 7 or a pen. It is recorded on the writing recorder 8.

The imaging unit is equipped with left and right optical stimulus generators 9L and 9R for applying optical stimulation, and a synchronization generator I for applying a synchronization signal to the imagers IL and IR. The output signal of the synchronization generator 10 is as follows.

Process amplifiers 2L, 2R, level detectors 3L, 3R.

It is also supplied to the detection devices 4L and 4R. Further, the stimulus generators 9L and 9R are blinked under the control of a stimulus control device 110 that operates based on commands from the data processing section 6. Also, monitor TV 1 for observing left and right images.
It can be connected to both 2L and 12R, making it effective for level detection monitoring.

The detection devices 4L and 4R will be described below. Detection of the area and diameter of the pupil at nine positions will be explained.

FIG. 2 shows the pupil displayed on the screen 12' of the television monitor. On a television screen, the pupil area is at a black level, and the rest is at a white level or a level close to white. Therefore, take advantage of this level difference.

The level detector 3 can extract a signal of the pupil area, that is, the black level.

The area of the pupil is determined by integrating the black level signal thus obtained.

Referring to FIG. 3, clock pulses from clock pulse generator 13 are input to counter 15 via gate 14. The gate 14 is opened by the black level output of the level detector 6 and an area signal, which will be described later. During this period, the counter 15 counts clock pulses. When this operation is performed for one frame, the counter holds a count proportional to the pupil area.

The latch circuit 16 is activated by the vertical synchronization pulse at the end of one frame.
Then, the count value of the counter is held, and then the delay circuit 17
With reference to FIG. 4, the counter 15 receives a pulse from
The output from the gate 14 in the figure is input to the force inputter 18,
It is cleared by a signal obtained by delaying the horizontal synchronizing signal by the delay circuit 19. Therefore, the counter 18 provides a count value proportional to the length of the black level during one horizontal scanning period.

This count therefore indicates the chord length of the pupil on the horizontal scan line. Color/li 1 white count value is comparator 20
is compared with the contents of the latch circuit 21 which provides the other input B as one input A. The output of the comparator 20 controls the opening and closing of the gate 22, and when A) is H, the horizontal synchronization signal is allowed to pass, and this horizontal synchronization signal writes the contents of the latch circuit 21 to the count value of the counter 18 at that time. change. Thus, the count of counter 18 for each horizontal scan is sequentially compared with the previous one.

A large count value is held in the latch circuit 21.

When this is repeated over one frame, the latch circuit 21 holds a value corresponding to the maximum horizontal chord or diameter of the pupil (indicated by D in FIG. 2). - The contents of the latch circuit 21 are held in the latch circuit 23 by the vertical synchronization pulse of the end of frame l, and the contents of the latch circuit 21 are cleared by the output pulse of the delay circuit 24. Thus, while entering a standby state for detecting the primary frame, a numerical value corresponding to the detected diameter is held in the latch circuit 23.

Referring to FIG. 2, the position of the pupil can be determined as the coordinates (x, y) of the center of the pupil when one corner of one screen is the origin.

This y is given by counting the number of scanning lines until the diameter is determined.

Referring to FIG. 5, a counter 25 counts horizontal synchronizing pulses and provides the counted value to a latch circuit 26. Counter 25 is also cleared by a vertical synchronization pulse. The latch circuit 26
With the output pulse of the gate 22 in the figure, the counter 25 at that time
The count value is maintained.

In Figure 4, when A<B, that is, after the diameter has been determined,
Since no pulse is output from the gate 22, the latch circuit 26 holds the number of horizontal scanning lines from the beginning of the -frame until the diameter is determined. - After the frame ends, the counter 25 is cleared by the vertical synchronization pulse and enters a waiting state for detection of the 9th frame.

X is the length of the white level up to the black level signal on the horizontal scanning line when the diameter is detected;
It is found by adding 2. That is, x=L+D/
It is 2.

Referring to FIG. 6, gate 28 is opened by the set output of flip-flop 27, which is set by the horizontal synchronizing signal and reset by the black level signal (output signal of detector 3).
- the clock pulses of the clock pulse generator 13 shown in the figure are passed through a gate 28 and counted by a counter 29; The horizontal synchronizing pulse is applied to the counter 29 through the delay circuit 30 to clear the counter 29.

Therefore, for each -horizontal scanning line, the clock pulses counted and held by the counter 29 are ε from the start until the black level signal appears. The output of the counter 29 is input to a latch circuit 31.

The latch circuit 31 is configured to hold the count value of the counter 29 at that time in response to a pulse from the gate 22 in FIG.

As mentioned above, the gate 22 passes the horizontal synchronizing pulse during A)B and does not output a pulse when A<H, that is, after the diameter is detected. Each time a horizontal scan is completed, the contents of the counter 29 (that is, the numerical value corresponding to the length from the start of the horizontal scan until the black level appears) are held one after another in the latch circuit.

After the diameter is detected, there is no b pulse from the gate 22, so the latch circuit 31 holds the last value held as it is. This value corresponds to L mentioned above.

On the other hand, as mentioned above, the diameter of the latch circuit 23 in FIG.
Since the latch circuit 230 output is held at 172
Through the division circuit 32, add (L + D/2)
is obtained.

In pupillary measurement, the pupil signal is detected based on the difference in brightness between the pupil and the iris, but in actual measurement, part of the screen may be as bright as the black level of the pupil due to the subject's eyelashes and eyelids. This may interfere with measurement. Disturbances also occur due to uneven lighting.

One way to solve this problem is to create an area B as shown in FIG. 7 within the screen 12', and make the determination of white/black only within that area, with everything outside the area being determined as a white level. Areas can be moved freely anywhere on the screen. Furthermore, the thickness of the area can also be freely changed vertically and horizontally. When the area is determined in a more precise manner, for example, when only diameter data is required, a horizontally elongated area B' as shown in FIG. 8 can be used to make measurements even on a screen with extremely poor image quality. However, in this case, it is impossible to measure the area. This area can be observed on a monitor as a white or black frame by superimposing it on the video signal.

This area signal is the area signal shown in FIG.

Specific examples will be described below.

In FIG. 9, the output of the adder 34 generates an output voltage as shown in FIG. generates an output voltage such as The output voltages of adders 34 and 35 are compared with a sharp tooth wave d generated in synchronization with a horizontal synchronization signal or a vertical synchronization signal by comparators 36 and 37, respectively. Since the output voltage of the adder 34 is always lower than the output voltage of the adder 35, the comparator 37 operates first and sets the flip-flop 68. Next, the controller 36 operates to reset the flip-flop 38. This situation is shown in FIG. 10e.
The part that is applied to the level becomes the area signal. When the position volume R4 is rotated, the adder output of 34.35 becomes the first
0 figures a, b to a/.

It moves in parallel like b'. In this case, the outputs of the controllers 36 and 37 are as shown in FIG. 10e. Leave the toe 9 area volume R2 as is and change the 9 position volume R4.
If you rotate , the area will not change and only the 9 positions will change.

Area volume R2 without changing position volume R4
When rotated, as shown in Fig. 11, the controller 34
, 35 trigger point changes from C to C',
The output of flip-flop 5B changes from e to e/ in FIG. At this time, the size of the area changes without changing the position. The same circuit can be used horizontally and vertically. In this case, only the constant of the integrator 39 changes. By horizontally and vertically ANDing the output E of flip-flop 38, the measurement area is determined.

Superimposition on the video signal is made possible by inserting some logic circuits based on the AND signals of the horizontal and vertical flip-flops 3B.

As described above, according to the present invention, not only the diameter and area of the pupil but also the center position of the pupil can be determined numerically by digital processing = Being able to determine the center position of the pupil means that the movement of the eyeball can be determined. This means that it can be determined numerically, expanding the range of applications of pupillometers in medicine and psychology.

Note that it is convenient to use a camera using a solid-state image sensor as the imager 1, and as the clock generator 16, a clock pulse to a bond sensor can be used.

[Brief explanation of the drawing]

Fig. 1 is an electrical system diagram showing the entire pupillometer according to an embodiment of the present invention, Fig. 2 is a diagram showing the pupil on a monitor television screen, and Fig. 3 is an example of a circuit for detecting the pupil area. 4 shows an example of a circuit for detecting pupil diameter, and FIG. 5 shows an example of a circuit for detecting pupil diameter.
FIG. 6 is a diagram showing an example of a circuit for detecting the distance y in the vertical direction to the center of the pupil. FIG. 6 is a diagram showing an example of a circuit for detecting the distance X in the horizontal direction to the center of the pupil. FIGS. A diagram showing a monitor TV screen when different detection areas are provided,
FIG. 9 is a diagram showing an example of a circuit for obtaining a detection area signal,
Both FIG. 0 and FIG. 11 are diagrams for explaining the operation of the circuit of FIG. 9. 3L, 3R... Level detection circuit, 13... Clock generator, 14... Game), 15.1B, 25
．． 29...Counter, 16, 21, 23, 26.
31...Latch circuit. 20... Comparator, 32... Division circuit. 66...Addition circuit. Continued from page 1 0 Inventor Watanabe Kentoride City Togashira 8-4-7 0 Inventor Shinyu Ono 3-5-25 Kamizono, Saga City

Claims (1)

[Scope of Claims] 1. In a pupillometer that obtains information regarding the pupil by processing a video signal obtained by photographing the anterior segment of the eye with a scanning camera, a black level signal indicating the pupil segment is obtained from the video signal. a clock pulse generating means, a gate means which is opened by the detected black level signal and allows the clock pulse to pass through, and a gate means which counts the clock pulses that have passed through the gate means and calculates the output of the video signal. A first color counter means that is cleared by a horizontal synchronizing signal, a first latch circuit means that reads and holds the count value of the color/return means, and a first latch circuit means that reads and holds the count value of the color/return means, and a first latch circuit means that reads and holds the count value of the color/return means, and a count value of the first latch circuit and the count value of the counter means. a comparator means that constantly compares the count value of the first counter means with the count value and causes the first latch circuit means to read and hold the count value when the count value of the first counter means is large; a second counter means for counting the clock pulses in the meantime; a second latch circuit means for reading and holding the output of the second counter means using the read and hold signal from the comparator means; third counter means for counting the signals;
third latch circuit means for reading and holding the count value of the third counter means using the read and hold signal from the comparator means; and adder circuit means for adding the contents of the latch circuit means, and at the end of one frame of the video signal, a numerical value corresponding to the pupil diameter is added to the output of the first latch circuit means, and the output of the third latch circuit is added. A pupillometer characterized in that a numerical value corresponding to a vertical distance (0) to the center of the pupil is outputted at the output of the adding circuit, and a numerical value corresponding to the horizontal distance (X) to the center of the pupil is outputted from the adding circuit. Below margin