JPS61255633A - Fixed sight monitor apparatus - 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 [Technical Field] The present invention relates to a fixation monitoring device, and more particularly to a fixation monitoring device for fixating an eye image used in a perimeter meter or the like.

[Prior Art] In an ophthalmological examination device such as a perimeter, it is important to determine the direction of the eyes, fixate the center of the eyes, and maintain the fixation state for a predetermined period of time during the examination of a subject. This is because if the eye image moves during the examination, it becomes difficult to measure the visual field. Conventionally, as a method for monitoring central fixation, a direct method is known in which the examiner looks through a finder and monitors the fixation state of the subject. This method places a heavy burden on the examiner, so an optical system is used to form an image of the eye to be examined, a single photoelectric conversion element is placed at that position, and the shift in fixation is monitored by the output fluctuations. method is known.

Further, as described in U.S. Pat. No. 418+11H3, the photoelectric conversion element is divided into a plurality of parts, preferably into four parts,
A method of monitoring the fixation state using the variation of the difference from two opposing photoelectric conversion elements is known.

[Problems to be Solved by the Invention] In the conventional device as described above, there is a problem that when the illuminance decreases, the sensitivity decreases and the output decreases, making it impossible to perform the function of maintaining the fixation state. .

Therefore, the present invention was made to solve these problems, and an object of the present invention is to provide a fixation monitoring device with high sensitivity.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention includes a plurality of photoelectric conversion elements that receive an eye image, an amplifier that amplifies the signal from each photoelectric conversion element, and an adjacent an adder that adds the amplified signals from each photoelectric conversion element, a subtracter that compares the outputs from each adder, an adder that sums up the outputs from each photoelectric conversion element, and an adder that adds the amplified signals from each photoelectric conversion element, It consists of an adder that adds together the outputs of the deviation amounts, and a divider that divides the outputs from the adders that sum the outputs of the adders and the outputs of the deviation amounts. We adopted a configuration that monitors the fixation state of the eye image using the output of the device.

[Function] In the present invention, after amplifying the output of the four-divided photoelectric conversion element with a preamplifier, an adder is provided that outputs two outputs of each adjacent divided photoelectric conversion element. ,
The output from this adder is compared using subtractors in the vertical and horizontal directions. The outputs from this subtracter are encoded in the absolute value circuit and then added in an adder that sums the outputs of the amount of deviation. Further, an adder 15 is provided that takes the sum of the outputs from each adder 13, and the output from the adder that takes the sum of the outputs of the deviation amounts is divided by the output of the adder that takes the sum, using a divider. Even when the illuminance of the eye examination is changed, the sensitivity to the amount of eye movement is kept constant and the fixation state is monitored.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

In FIG.
A state in which an image of the eye to be examined is formed on the photoelectric conversion element ll consisting of d is illustrated. Each photoelectric conversion element 11a to lid
The tangent line between them is X.

They are arranged in the Y direction.

These four-divided photoelectric conversion elements 11a to 11lid are connected to preamplifiers 122L to 12d, respectively, as shown in FIGS. 2, 3, and 4.
The output of
The output of 2c is sent to the adder 13b, and the preamplifier 12c,
The output of 12d is sent to adder 13c, and amplifiers 12d and 1
The outputs of 2a are respectively connected to adders 13d. In this way, the adders 13a to 13d add the respective outputs of the adjacent photoelectric conversion elements 11a to lid.

Further, the outputs of the adders 13a and 13c are connected to a subtracter 14a, and the outputs of the adders 13b and 13d are connected to a subtracter 14b, which is further connected to the adder 13b.

The output of 13d is input to adder 15. This subtractor 1
The sum (11a+1lb) of the outputs of adjacent photoelectric conversion elements facing each other by the subtracter 14 composed of 4a and 14b,
(11c+11d) and (11b+11c), (ll
d+11a) is taken. Further, in the adder 15, the sum of each photoelectric conversion element 11a to lid is calculated. The output of the subtracter 14 is connected to an initial value zeroing and holding circuit 16, which is connected via an absolute value circuit 17 to an adder 18, whose output is then connected to a divider 19. Further, the output of the adder 15 is input to the divider 19, and the output of the adder 15 is input to the divider 19.
9 divides the outputs from the adders 15 and 18, and the output of the divider 19 is output as a signal for monitoring the fixation state.

Next, the operation of the fixation monitoring device configured as described above will be explained.

First, the eye image set on a perimeter, etc. is passed through the optical system to the first
An image is formed on the photoelectric conversion element 11 as shown in the figure.

Output signals from the photoelectric conversion elements 11a to lid are amplified by preamplifiers 12a to 12d, respectively, and then outputs from adjacent photoelectric conversion elements are added by adders 13a to 13d, respectively. Subsequently, each of the outputs added in this way is subtracted by subtracters 14a and 14b, respectively, and subtraction is performed for each pair facing each other, that is, for each pair in the X direction and the Y direction. The output of the subtracter 14 is input to an initial value zeroing/holding circuit 16, whereby the initial value is zeroed and held in order to use the difference output in the initial, fixated state as a reference.

If the fixation shifts here, the balance will be disrupted, and an output will be generated in accordance with the amount of shift. The outputs resulting from the deviations in the X and Y directions generated here are encoded in the same manner in the absolute value circuit 17, and then added in the adder 18, and the sum of the deviation amount outputs is output. On the other hand, since the adder 15 calculates the sum of the outputs of each photoelectric conversion element, the divider 19 divides the sum of the deviation amount output and the sum of each element to obtain a signal for monitoring the fixation state. Take out the signal. This division circuit allows the sensitivity to the amount of eye movement to be kept constant even when the illuminance of the eye to be examined is changed.

Here, considering the X direction, the output signals of each photoelectric conversion element 11a to lid are 11b+llc, l
After being converted into the form ld+11a, it is subtracted by the subtracter 14. Therefore, the magnitude of the output is approximately 2 times higher than that of the conventional method, which takes the difference between the outputs of each photoelectric conversion element individually, such as lla and llc, or llb and lid.
It will be doubled. The same can be said about the Y direction.

Although the embodiment described above is an example in which the photoelectric conversion element is divided into four parts, the present invention is not limited to this, and it goes without saying that photoelectric conversion elements divided into an even number of four or more parts may be used.

[Effects of the Invention] As explained above, according to the present invention, adjacent photoelectric conversion elements are once added, and then a set of opposing photoelectric conversion elements is subtracted, so that unlike conventional devices, Compared to the previous method, where the signal to start fixation was detected from the difference between each photoelectric conversion element, the sensitivity is approximately twice as high in the illuminance of the subject's eye, allowing the function to be maintained even in low illuminance conditions. A fixation monitoring device can be obtained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an eye image formed on a photoelectric conversion element, Fig. 2 is a schematic block diagram showing the overall configuration of the device of the present invention, and Fig. 3 is a block diagram shown in the upper part of Fig. 2. FIG. 4 is a block diagram showing a more detailed configuration of the blow 2 shown in FIG.
FIG. 2 is a circuit diagram showing a detailed circuit of the diagram. 11...Photoelectric conversion element 12...Preamplifier 13.15.18...Adder 14...Subtractor 16...Initial value zeroing holding circuit 17...Absolute value circuit 19...・Divider

Claims (1)

[Claims] A plurality of photoelectric conversion elements that receive an eye image, an amplifier that amplifies the signal from each photoelectric conversion element, an adder that adds the amplified signals from each adjacent photoelectric conversion element, and an output from each adder. a subtracter for comparison, an adder for summing the outputs from each photoelectric conversion element, an adder for adding the outputs from the subtracters and summing the outputs of the deviation amount, and an output from the adder for summing. and a divider that divides the output from the adder that takes the sum of the outputs of the amount of deviation, and is used in a perimeter meter characterized in that the fixation state of the eye image is monitored by the output of the divider. Fixation monitoring device.