JPH0277230A - Non-contact eye pressure meter - Google Patents

Abstract

PURPOSE:To surely detect the abnormality of a fluid compression system and to find out the abnormality in an early stage by discriminating whether the operation of the fluid compression system is proper or improper according to whether a time until the output of a pressure measuring means to measure the pressure in a compressing room reaches a prescribed value exists within a prescribed range or not. CONSTITUTION:In order to discriminate whether the operation of the fluid compression system is proper or improper, a pressure sensor 4 to detect an air pressure in a cylinder 1 and a reference timer 7 are used. When a switch 10 for a self-diagnosis is turned on, a counter 6 is started at a time tb when the pressure in the cylinder 1 reaches a certain prescribed value Pb after a solenoid is energized 3 at a time ta from the relation of a time-pressure after the solenoid is energized, and the counter 6 is stopped at a time tc when the pressure is compressed to another prescribed value Pc. When a counted value (tc-tb) exists within a range to be decided beforehand, the fact that the fluid compression system is normally operated is decided by a CPU 12, and when the value is outside the range, the abnormality is decided.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a non-contact tonometer that deforms the cornea by spraying compressed fluid onto the eye to be examined, and measures the intraocular pressure of the eye to be examined based on the deformed state. Regarding.

[Prior Art] It is known from Japanese Patent Publication No. 38437/1983 that an intraocular pressure value is calculated by spraying a compressed fluid onto the eye to be examined and measuring the time until the cornea undergoes a predetermined deformation. In this case, variations in the mechanical movement of the piston of the fluid compression system will affect the accuracy of intraocular pressure measurement. As an improvement on this, it is known in Japanese Utility Model Application Laid-open No. 59-143402 that the intraocular pressure value is calculated by measuring the internal pressure of a cylinder serving as a compression chamber of a fluid compression system when the cornea is deformed to a predetermined degree.

[Problems to be Solved by the Invention] By measuring the pressure inside the compression chamber, it is possible to accurately measure intraocular pressure even if there is some abnormality in the fluid compression system regarding mechanical movement, etc.; The future is fluid pressure! It is desirable to have a system in which the I system does not operate at all.

[Means for Solving the Problems] The present invention includes a pressure measuring means for measuring the pressure inside a compression chamber, a time measuring means for measuring elapsed time, and a method based on the output of the pressure measuring means and the output of the time measuring means. The fluid compression system is characterized by comprising a calculation means for determining whether or not the operation of the fluid compression system is appropriate.

[Embodiment] FIG. 1 is a block diagram of an embodiment of the present invention. When measuring intraocular pressure, the CPU 12 starts the measurement based on the signal.
A command is given to the solenoid drive circuit 9 via the interface circuit 11. As a result, the rotary solenoid 3 is energized and the piston 2 is operated, so that the air in the cylinder 1, which serves as a compression chamber, is compressed in a temporally variable manner. The compressed air is ejected toward the corneal apex EC, deforming the cornea, and the deformed state is optically detected. That is, the light emitted from the light source 13 is converted into a parallel beam by the lens 14 and directed toward the angle Bi E c, and the beam reflected by the cornea is received by the photodetector 16 provided at its focal position via the lens 15. Here, since the light source 13 and the photodetector 16 are arranged optically conjugately via corneal reflection when the cornea is in a predetermined deformation (for example, applanation) state, the amount of light received by the photodetector 16 is determined by the amount of light received by the photodetector 16 when the cornea is in a predetermined deformation state It reaches its maximum when

The air pressure in the cylinder 1 as a compression chamber is constantly detected by a pressure sensor 4, passes through an amplifier 5, is digitized in an A/D converter 8, and enters an interface circuit 11. Then, the CPU 12 calculates the intraocular pressure value from the output of the pressure sensor 4 when the output of the photodetector 16 is maximum.

Here, the fluid compression system is composed of members 1, 2, and 3.9, and a pressure sensor 4 and a reference timer (reference clock) 7 are used to determine whether or not the fluid compression system is operating properly. The self-diagnosis switch 10 is then turned on to determine whether or not the fluid compression system is operating properly.

FIG. 2 is a diagram showing the relationship between time and pressure after energizing the solenoid. After energizing the solenoid 3 at time t1,
Time tb when the pressure inside cylinder 1 reaches a certain predetermined value P
”, and stops the counter 6 at the time tc when the pressure is compressed to another predetermined value PC.Then, when the counter value (corresponding to tc-tb) falls within a predetermined range, the counter 6 is stopped. CPU1 when
2, it is determined that the fluid compression system is operating normally, and if it is outside the range, it is determined to be abnormal.

FIG. 3 represents another embodiment of the invention. Same as the above example <1. At this point, the solenoid is energized,
At the time td when the pressure reaches the predetermined value Pd, the reference timer 7 is reset.

Here, the reference timer 7 is preset with a time corresponding to the reference time shown in FIG. As a result, the counter 6 in FIG. 2 is omitted. 1. After the reference timer 7 is reset at , the fluid compression system is normal when the value of Po is within a certain range after the reference time has elapsed, that is, using the pressure P6 at point 70, and when it is outside the range, it is abnormal. It will be considered as

By the way, as a self-diagnosis, the time from energization of the solenoid to the pressure reaching Pb (tb - ta) in Fig. 2
It is also possible to check whether the value is within a predetermined range.

It is also possible to simply check whether the pressure value of Pd at time td in FIG. 3 is within a predetermined range.

If an abnormality is detected at t or tll, it is possible to stop energizing the solenoid 3 at an early stage and forcibly stop the measurement without blowing out unnecessary air into the cornea of the subject's eye. It becomes possible.

FIG. 4 is a time-pressure relationship diagram when the simple check is performed and the measurement is continued because it is considered normal, and when it is judged to be abnormal and the measurement is interrupted, and 4-A shows the former,
4-B represents the latter.

In the above-described embodiment, the self-diagnosis switch 10 is used to perform self-diagnosis at any time, but the device may automatically perform this every time immediately after the power supply is turned on.

Furthermore, in the above-described embodiment, it was described that the suitability of the fluid compression system in a non-contact tonometer that measures the pressure inside the compression chamber when the cornea undergoes a predetermined deformation is checked. It is clear that the suitability of the fluid compression system can also be checked in a non-contact tonometer that measures time.

[Effects of the Invention] As described above, according to the present invention, an abnormality in a fluid compression system can be reliably detected, and the abnormality can be detected early.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 and 3 are 1. An explanatory diagram of the second embodiment. Fig. 4 is an explanatory diagram when an abnormality is detected early and subsequent fluid ejection is stopped. In the figure, 1-m-cylinder 2-m-piston 3-m-solenoid 4 --One pressure sensor 5-m-Amplifier 6--One counter 7-m-Reference timer 8--A/D converter 9-m-Solenoid drive circuit 10--Self-diagnosis switch 11--Interface circuit 12- -CPU Ec-1 is the cornea of the eye to be examined. iη stone ““

Claims (1)

[Scope of Claims] 1. A fluid compression system that sprays fluid within a compression chamber toward the cornea of the eye to be examined outside the compression chamber in a temporally variable manner, and a corneal deformation system that detects deformation of the cornea of the eye to be examined due to the fluid compression system. A non-contact tonometer equipped with a detection system, comprising: a pressure measuring means for measuring the pressure inside the compression chamber; a time measuring means for measuring elapsed time; A non-contact tonometer characterized by comprising a calculation means for determining whether or not the fluid compression system is operating properly. 2. The non-contact tonometer according to claim 1, wherein the calculation means determines whether or not the operation of the fluid compression system is appropriate based on whether or not the time taken for the fluid pressure in the compression chamber to reach a predetermined value is within a predetermined range. . 3. The non-contact system according to claim 1, wherein the calculation means determines whether or not the fluid compression system is properly operated based on whether the fluid pressure within the compression chamber is within a predetermined range after a predetermined time has elapsed from a predetermined time. Tonometer.