JPH0624519B2 - Non-contact tonometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a fluid discharge means for discharging a fluid toward a cornea of an eye to be examined, a fluid discharge axis line of the fluid discharge means, and the cornea thereof. Alignment detecting means for detecting the alignment with the apex of each of them and outputting an alignment signal, and determining whether or not the alignment is completed by receiving the alignment signal of the alignment detecting means, and when the alignment is completed, the alignment is detected. The present invention relates to an improvement of a non-contact tonometer which has a control means for outputting a completion signal and automatically executes fluid discharge of the fluid discharge means based on the alignment completion signal.

(Prior Art) Conventionally, for example, Japanese Patent Publication No. 58-341 has been used for a non-contact tonometer.
The one disclosed in Japanese Patent Publication No. 28 is known. This conventional non-contact tonometer detects the completion of alignment between a device as a fluid discharge means for discharging a fluid toward the cornea of an eye to be inspected, and the axis of the device as a fluid discharge axis and the apex of the cornea. In order to do so, the cornea is irradiated with infrared light from the axial direction of the device, the infrared reflected light from the cornea in the axial direction is received by the photoelectric conversion element, and the alignment signal is output from the photoelectric conversion element. And a control means for receiving an alignment signal from the alignment detecting means to determine whether or not the alignment is completed, and for outputting an alignment completion signal when the alignment is completed. . The control means compares the received light amount signal value of the photoelectric conversion element with a set received light amount signal value corresponding to the received light amount of the photoelectric conversion element when the apex of the cornea coincides with the axis, and the deviation signal When the value is below a certain value, the alignment completion signal is output, and at the same time when the alignment between the axis of the device and the apex of the cornea is completed, an air pulse as a fluid automatically enters the cornea of the eye to be examined. The eye pressure of the eye to be inspected is measured based on the time from when the air pulse is blown to the cornea from the axial direction of the device until the cornea is flattened. ing.

(Problems to be Solved by the Invention) However, in this conventional non-contact tonometer, after the air pulse is discharged as a fluid based on the alignment completion signal, the measurement of the intraocular pressure is completed, When the alignment is accidentally completed by the prefectural eye, there is a problem that the air pulse may be emitted again after the air pulse after the previous one. In particular, in the case of an eye to be examined that has a large amount of involuntary eye movement, in the case of a child with a small involuntary eye ability, it is prone to look aside, alignment completion and non-completion are repeated within a minute time, and in each case air pulse emission occurs, Moreover, before the desired volume of air is sucked into the cylinder of the device, the previous air pulse discharge is performed and the subsequent air pulse discharge is performed.

Therefore, an object of the present invention is to provide a non-contact tonometer that can solve the problems of the above-mentioned conventional techniques.

In order to achieve the above object, the non-contact tonometer according to the present invention receives an alignment signal from an alignment detection unit that detects the alignment between the fluid discharge axis of the fluid discharge unit and the apex of the cornea. Control unit that determines whether or not the alignment is completed, and outputs the alignment completion signal when the alignment is completed, the fluid discharge after the successive fluid discharges is prohibited for a predetermined time from the previous fluid discharge. As described above, a delay means for delaying the later fluid discharge from the previous fluid discharge by a predetermined time is provided.

(Operation) According to the non-contact tonometer according to the present invention, when the alignment signal is input from the alignment detection means to the control means, the control means receives the alignment signal and determines whether or not the alignment is completed. When the alignment is completed, the alignment completion signal is output. As a result, the fluid discharging means automatically starts discharging the fluid, but even if the alignment completion signal for starting the fluid discharging after the successive fluid discharging is output, the alignment completion signal prohibits the subsequent fluid discharging. If the fluid is output within a predetermined time, the fluid release following the previous fluid release is prohibited.

(Example) Below, the Example of the non-contact tonometer concerning this invention is described, referring drawings.

FIG. 1 is a block diagram showing a main configuration of a non-contact tonometer according to the present invention, in which 1 is a fluid discharge means,
Reference numeral 2 is an alignment detection means, and 3 is a control means. The fluid discharge means 1 has a function of discharging an air pulse as a fluid toward a cornea of an eye to be examined (not shown), and a symbol m is a fluid discharge axis line thereof. The alignment detection means 2 has a function of detecting the alignment between the fluid discharge axis m and the apex of the cornea and outputting the index detection signal Va as an alignment signal. The alignment detecting means 2 has a photoelectric conversion element (not shown), and the index detection signal Va is output from the photoelectric conversion element.
It corresponds to the one disclosed in Japanese Patent Publication No. 58-34128 and the one described in Japanese Patent Application No. 60-59994 previously filed by the applicant. The control means 3 has a function of receiving the index detection signal Va, determining whether or not the alignment is completed, and outputting an alignment completion signal S ₁ when the alignment is completed.

The control means 3 includes a comparator 4 and a reference value generation circuit 5. The comparator 4 has an index detection signal V at its one terminal.
a is input, and the reference voltage Vc of the reference value generation circuit 5 is applied to the other terminals. This reference voltage Vc is for determining whether or not the alignment between the fluid discharge axis m and the apex of the cornea is completed, and the comparator 4 compares the reference voltage Vc with the index detection signal Va and Index detection signal Va
When the amplitude is larger than the reference voltage Vc, it is determined that the alignment is completed, the output terminal thereof becomes H level, and the alignment completion signal S ₁ is H level when the alignment is completed.

The output terminal of the comparator 4 is connected to one terminal of the AND circuit 6, and the output terminal of the delay timer 7 is connected to the other terminals. The delay timer 7 has a normally closed contact (not shown). The normally closed contact is closed when the delay timer 7 is not timing and is open when the delay timer 7 is timing. The delay timer 7, and outputs the inhibit signal S _2, the meaning of the inhibit signal S _2, it will be described later functions of the delay timer 7.

The prohibition signal S ₂ is output to the AND circuit 6 through the normally closed contact. The prohibition signal S ₂ is at H level while the delay timer 7 is not timing and is at L level during the timing. The timing start signal for causing the delay timer 7 to start timing will be described later.

The output terminal of the AND circuit 6 is connected to the base of the transistor 9 via the resistor 8. This AND circuit 6
When the alignment completion signal S ₁ and the inhibition signal S ₂ are at the H level, their output terminals are at the H level, and the operation signal S ₃ for turning on the transistor 9 is output.
The transistor 9 functions as a switching circuit that controls the timing of the timer 10. As the timer 10, a power-on reset type timer is used here, and every time the transistor 9 is activated and powered on, the timekeeping content that was being timed is cleared and the timekeeping is restarted. It is like this.

The timer 10 outputs the execution command signal S ₄ for starting the fluid discharge to the fluid discharge means 1 and the delay timer 7 after measuring a predetermined time. Here, the predetermined time is set to 0.2 seconds in consideration of the involuntary eye movement of the eye to be examined. When the execution command signal S ₄ is input to the fluid discharge means 1,
The fluid ejection is performed automatically, whereby an air pulse is blown onto the cornea of the eye to be examined.

If the alignment is not accurate, look aside the subject,
Even if the alignment completion signal S ₁ is output from the comparator 4 due to an accidental cause such as an involuntary eye movement of the eye to be inspected, the time when the alignment completion signal S ₁ is at the H level is instantaneous and 0.2 Since it is less than a second, the alignment completion signal S ₁ becomes L level at the next moment, and the transistor 9 stops its operation during the time counting of the predetermined time of the timer 10.
Therefore, the execution command signal S ₄ is not output, and it is possible to avoid the intraocular pressure measurement based on an accidental cause such as the involuntary eye movement.

That is, the transistor 9 and the timer 10 monitor the alignment completion state for a predetermined time based on the alignment completion signal, and the alignment completion state continues to be established for the predetermined time and the alignment completion state is maintained. It functions as the monitoring means 11 which outputs the execution command signal S ₄ to the fluid discharge means 1 only when it is maintained.

The execution command signal S ₄ here also functions as a timing start signal of the delay timer 7, and the delay timer 7
Starts timing based on the execution command signal. The delay timer 7 functions as a delay means for delaying the later fluid discharge from the previous fluid discharge for a predetermined time so that the fluid discharge after the successive fluid discharge is prohibited from the previous fluid discharge for a predetermined time. Here, the predetermined time of the delay timer 7 is set to 2 to 5 seconds in consideration of the time required to suck a desired volume of air into the cylinder of the device (not shown) of the fluid discharge means 1. After a predetermined time has passed, the timekeeping is stopped to close the normally closed contact from the open state, and the prohibition signal S output from the timer 7 is output.
₂ has the meaning of prohibiting the start of the timer 10 for discharging the fluid after the successive discharge of the fluid for a predetermined time.

That is, the normally closed contact is the execution command signal S ₄
When the delay timer 7 is opened when the delay timer 7 starts counting, the prohibition signal S ₂ becomes L level for a predetermined time, the output terminal of the AND circuit 6 becomes L level, and the transistor 9
Turns from on to off and timer 10 stops its timing. Therefore, while the delay timer 7 is measuring the time, it is determined that the alignment is completed, the alignment completion signal S ₁ is output, and the alignment completion state is the required time 0.2.
Even if it is connected for more than a second, the execution command signal S ₄ is not output from the timer 10, the fluid discharge after the fluid discharge means 1 is prohibited, and the desired volume of air is sucked into the cylinder from the previous fluid discharge. The fluid is not discharged after that for a predetermined time until the temperature is reached, and incomplete continuous discharge of the fluid can be prevented.

In this embodiment, the execution command signal S ₄ is used to start the timing of the delay timer 7. However, instead of using the execution command signal S ₄ , the pressure output from the known applanation detection means 12 is used. Delay timer 7 using the flat detection signal Sa
It is also possible to start the timing of.

Further, in this embodiment, the fluid discharge means 1 discharges the fluid based on the execution command signal S ₄ of the monitor means 11. However, the present invention can be realized without the monitor means 11. In this case, the fluid discharge is started based on the operation signal S ₃ of the AND circuit 6, and at this time, the alignment completion signal is continuously generated due to an accidental cause such as the involuntary eye movement of the eye to be inspected or the examinee looking aside. Is output and even if the alignment completion state does not continue for a certain period of time, it is possible to prohibit the fluid discharge after the successive fluid discharges for a predetermined time from the previous fluid discharge.

[Effects of the Invention] As described above, the non-contact tonometer according to the present invention is
An alignment completion signal is received when the alignment signal of the alignment detection means for detecting the alignment between the fluid ejection axis of the fluid ejection means and the apex of the cornea is received and whether or not the alignment is completed. The control means for outputting is provided with a delay means for delaying the subsequent fluid discharge from the previous fluid discharge for a predetermined time so that the subsequent fluid discharge is prohibited from the previous fluid discharge for a predetermined time. Therefore, it is possible to avoid the incomplete continuous ejection of the fluid due to an accidental cause such as the inattentive look of the subject and the involuntary eye movement of the subject's eye, thus minimizing the measurement error.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a non-contact tonometer according to the present invention. 1 ... Fluid discharge means 2 ... Alignment detection means 3 ... Control means 4 ... Comparator 6 ... AND circuit 7 ... Delay timer 9 ... Transistor 10 ... Timer m ... Fluid discharge axis Va ... Index Detection signal S ₂ …… Inhibition signal S ₃ …… Alignment completion signal S ₄ …… Execution command signal

Claims (2)

[Claims] 1. A fluid ejecting means for ejecting a fluid toward a cornea of an eye to be examined, and an alignment detecting means for detecting an alignment between a fluid ejecting axis of the fluid ejecting means and an apex of the cornea and outputting an alignment signal. And a control means for determining whether or not the alignment is completed by receiving the alignment signal from the alignment detection means, and outputting an alignment completion signal when the alignment is completed, based on the alignment completion signal. In the non-contact tonometer that automatically executes the fluid discharge of the fluid discharge means, the control means is configured to control the fluid discharge after the successive fluid discharges for a predetermined time from the previous fluid discharges. A non-contact tonometer, comprising delay means for delaying the discharge of the fluid from the previous discharge of the fluid for a predetermined time. 2. The control means outputs an execution command signal for starting fluid discharge of the fluid discharge means based on the alignment completion signal, and the delay means delays for starting timing based on the execution command signal. The non-contact tonometer according to claim 1, wherein the non-contact tonometer is a timer.