Non-contact tonometer

Abstract

To provide a non-contact tonometer which can reduce a capacity of capacitor, power capacity and size of a power source.SOLUTION: A tonometer includes: an electric actuator (solenoid 34g) that compresses the air inside a cylinder 34d by a piston 34f; a nozzle 21b communicating with an inside of the cylinder and blowing an air compressed by the piston onto a subject eye; a capacitor 46 for discharging the electric charge accumulated by charging and supply a first drive current (drive current I2) to the electric actuator; and a power source 42 which can execute a charging of the capacitor and a supply of second drive current (drive current I1) to the electric actuator. The electric actuator operates upon receiving a supply of the first drive current from the capacitor and a supply of the second drive current from the power source.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a non-contact tonometer that measures the intraocular pressure of a subject's eye without contact. [Background technology]

[0002] A non-contact tonometer that measures the intraocular pressure of a subject's eye without contact is known (see, for example, Patent Document 1). A non-contact tonometer is provided with a blowing mechanism that blows air from a nozzle onto the cornea of ​​the subject's eye. The non-contact tonometer thus measures the intraocular pressure of the subject's eye without contacting the cornea by driving the blowing mechanism to blow air from the nozzle onto the cornea of ​​the subject's eye, thereby deforming the cornea and detecting the state of deformation.

[0003] The spray mechanism of the non-contact tonometer described in Patent Document 1 is composed of a cylinder, a piston, a nozzle, a chamber, and a solenoid (such as a rotary solenoid). The piston is movably provided inside the cylinder. The nozzle is connected to the chamber and communicates with the inside of the cylinder (pressurizing chamber) via the chamber. The solenoid is connected to the piston.

[0004] The solenoid is an electric actuator connected to a capacitor. The capacitor is charged by a power source (charging circuit) and then discharges the accumulated charge to supply a driving current to the solenoid. The solenoid operates by receiving the driving current from the capacitor, causing the piston to move inside the cylinder. As a result, the air inside the cylinder is compressed by the piston and ejected from the nozzle toward the cornea of ​​the test eye via a chamber or the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-19044 Summary of the Invention [Problem to be solved by the invention]

[0006] In the non-contact tonometer described in Patent Document 1, the solenoid is driven solely by the drive current supplied from the capacitor, which requires a large capacitor capacity, and as a result, the power supply that charges this capacitor must also have a large power capacity. A power supply with a large power capacity is also large in size, which results in a large non-contact tonometer. Furthermore, a power supply with a large power capacity becomes over-specified during times when the solenoid is not being driven (during measurement standby, auto-alignment, and result analysis).

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a non-contact tonometer that can reduce the capacitance of the capacitor and the power capacity and size of the power supply. [Means for solving the problem]

[0008] A non-contact tonometer for achieving the object of the present invention comprises a cylinder, a piston movably provided inside the cylinder, an electric actuator that moves the piston inside the cylinder and compresses the air inside the cylinder with the piston, a nozzle that communicates with the inside of the cylinder and sprays the air compressed by the piston onto the subject's eye, a capacitor that discharges electric charges accumulated by charging and supplies a first drive current to the electric actuator, and a power source that is capable of charging the capacitor and supplying a second drive current to the electric actuator; The electric actuator operates by receiving both the first drive current supplied from the capacitor and the second drive current supplied from the power supply.

[0009] According to this non-contact tonometer, the capacitance of the capacitor and the power supply capacity and size of the power supply can be reduced.

[0010] A non-contact tonometer according to another aspect of the present invention includes a current limiting circuit that limits the charging current supplied from the power supply to the capacitor and the second drive current supplied from the power supply to the electric actuator. This limits the current supplied to the capacitor and the electric actuator, thereby suppressing the occurrence of inrush current when charging of the capacitor begins and preventing damage to various electronic components.

[0011] In a non-contact tonometer according to another aspect of the present invention, the current limiting circuit is a load switch.

[0012] A non-contact tonometer according to another aspect of the present invention includes a current supply switching control unit that switches ON / OFF of the supply of the first drive current and the second drive current to the electric actuator.

[0013] In a non-contact tonometer according to another aspect of the present invention, when the current supply switching control unit switches the supply of the first drive current and the second drive current to the electric actuator from ON to OFF, the power supply charges the capacitor, thereby recharging the capacitor.

[0014] In a non-contact tonometer according to another aspect of the present invention, the magnitude of the first drive current is different from the magnitude of the second drive current.

[0015] In a non-contact tonometer according to another aspect of the present invention, the current supply switching control unit selectively charges the capacitor with the power supply and supplies the second drive current from the power supply to the electric actuator.

[0016] In the non-contact tonometer according to another aspect of the present invention, the electric actuator is a solenoid. [Effects of the Invention]

[0017] The present invention can reduce the capacitance of the capacitor and the power supply capacity and size of the power supply. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view of a non-contact tonometer. [Figure 2] FIG. 2 is a schematic top view of a plurality of types of optical systems in the measurement head as viewed from above (Y direction). [Figure 3] FIG. 2 is a schematic side view of a plurality of types of optical systems in the measurement head as viewed from the side (X direction). [Figure 4] FIG. 2 is a schematic diagram of a drive current supply unit. [Figure 5] FIG. 2 is a functional block diagram of a control device. [Figure 6] FIG. 10 is a diagram showing the applanation signal output from the applanation detection optical system, the pressure signal output from the pressure sensor, the ON / OFF of the trigger signal output from the solenoid drive circuit, the charge / discharge state of the capacitor, and the current output from the power supply after auto-alignment is completed. [Figure 7] 10 is a flowchart showing the flow of a process for measuring the intraocular pressure of an eye to be examined using a non-contact tonometer. DETAILED DESCRIPTION OF THE INVENTION

[0019] [Configuration of non-contact tonometer 10] Fig. 1 is a side view of a non-contact tonometer 10. As shown in Fig. 1, the non-contact tonometer 10 measures the intraocular pressure value of a subject's eye E in a non-contact manner. The non-contact tonometer 10 includes a base 11, a face support unit 12, a moving mechanism 13, a measurement head 14, a monitor 15, and a control device 16.

[0020] In the drawing, of the mutually orthogonal X, Y, and Z directions (three axis directions), the Y direction is the up-down direction, the Z direction is the front-back direction (also called the working distance direction) that moves toward or away from the subject (subject's eye E), and the X direction is the left-right direction that is perpendicular to both the up-down direction and the front-back direction. In addition, in the Z direction (front-back direction), the side that moves toward the subject's eye E (subject) is called the front side in the Z direction, and the side that moves away from the subject's eye E (subject) is called the rear side in the Z direction.

[0021] A face support unit 12 and a movement mechanism 13 are provided on the base 11 from the front side in the Z direction to the rear side in the Z direction.

[0022] The face support part 12 is fixed to the base 11. The face support part 12 is provided with a chin rest part 12a that supports the subject's chin, a forehead rest part 12b that the subject's forehead abuts, and a pair of supports 12c that support the forehead rest part 12b, and supports the subject's face.

[0023] The moving mechanism 13 holds the measuring head 14 so that it can move in the X, Y, and Z directions.

[0024] The measurement head 14 measures the intraocular pressure value of the subject's eye E in a non-contact manner by blowing air from the nozzle 21b toward the cornea Ec (see Figure 2) of the subject's eye E to deform the cornea Ec and detect the deformed state.

[0025] The monitor 15 is, for example, a touch panel monitor, and is attached to the rear side of the measurement head 14. Under the control of the control device 16 described below, the monitor 15 displays various images including a photographed image (observation image) of the subject's eye E photographed by the measurement head 14, measurement results of the intraocular pressure value of the subject's eye E, and a menu screen for performing various operations and settings.

[0026] The control device 16 is connected to the above-mentioned moving mechanism 13, the measurement head 14, the monitor 15, etc. This control device 16 controls the auto-alignment of the measurement head 14 with respect to the subject's eye E and the measurement of the intraocular pressure of the subject's eye E by the measurement head 14.

[0027] Fig. 2 is a schematic top view of the multiple types of optical systems in the measurement head 14 as seen from above (Y direction). Fig. 3 is a schematic side view of the multiple types of optical systems in the measurement head 14 as seen from the side (X direction).

[0028] As shown in Figures 2 and 3, the measurement head 14 includes an anterior segment observation optical system 21, an XY alignment index projection optical system 22, a fixation target projection optical system 23, an applanation detection optical system 24, a Z alignment index projection optical system 25, a Z alignment detection optical system 26, and a spraying mechanism 34.

[0029] The anterior-segment observation optical system 21 is used for observing the anterior segment of the subject's eye E and for XY alignment of the measurement head 14 in the XY directions with respect to the subject's eye E. An anterior-segment illumination light source 21a (see FIG. 2) is provided in this anterior-segment observation optical system 21. Also provided on the optical axis O1 of the anterior-segment observation optical system 21 are an air-blowing nozzle 21b, an anterior-segment window glass 21c (see FIG. 3) that holds the tip of the nozzle 21b, a chamber window glass 21d, a half mirror 21e, a half mirror 21g, an objective lens 21f, and an image sensor 21i.

[0030] A plurality of anterior-segment illumination light sources 21a are provided around the anterior-segment window glass 21c, and directly illuminate the anterior segment of the subject's eye E.

[0031] The nozzle 21b is connected to a chamber 34a (see FIG. 3) of the spraying mechanism 34, and blows air onto the cornea Ec of the eye E to be examined.

[0032] An image of the anterior segment of the subject's eye E (image light from the anterior segment) passes outside the nozzle 21b, passes through the anterior segment window glass 21c, the glass plate 34b described below, the chamber window glass 21d, the half mirror 21g, and the half mirror 21e, and is formed on the light receiving surface of the imaging element 21i by the objective lens 21f.

[0033] The imaging element 21i is, for example, a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type image sensor. The imaging element 21i captures an image of the anterior segment incident on its light receiving surface to generate an imaging signal, and outputs the imaging signal to the control device 16. As a result, under the control of the control device 16, an observation image of the anterior segment of the subject's eye E based on the imaging signal output from the imaging element 21i is displayed on the monitor 15.

[0034] The anterior-segment observation optical system 21 also guides the XY alignment index light projected onto the subject's eye E from the XY alignment index projecting optical system 22 (described later) reflected by the cornea Ec to the light-receiving surface of the image sensor 21i. This reflected light passes through the nozzle 21b, the chamber window glass 21d, the half mirror 21g, and the half mirror 21e, and is imaged on the light-receiving surface of the image sensor 21i by the objective lens 21f. As a result, an XY spot is formed on the light-receiving surface of the image sensor 21i at a position corresponding to the positional relationship (relative position) between the measurement head 14 and the cornea Ec in the XY directions. As a result, XY alignment detection can be performed to detect the relative position of the subject's eye E in the XY directions with respect to the measurement head 14.

[0035] The image sensor 21i captures an image of the XY spot formed on its light receiving surface and outputs an image signal of the XY spot to the control device 16. As a result, under the control of the control device 16, the observed image of the anterior segment and the XY spot are superimposed and displayed on the monitor 15. Note that the monitor 15 also displays an alignment assistance mark.

[0036] The XY alignment index projection optical system 22 projects XY alignment index light from the front onto the cornea Ec of the subject's eye E. This XY alignment index light is used for XY alignment of the measurement head 14 with respect to the subject's eye E. The XY alignment index light is also used to measure the intraocular pressure value of the subject's eye E. Hereinafter, the reflected light of the XY alignment index light by the cornea Ec will be simply abbreviated as "XY index reflected light."

[0037] The XY alignment target projection optical system 22 includes an XY alignment light source 22a, a condenser lens 22b, an aperture stop 22c, a pinhole plate 22d, a dichroic mirror 22e, and a collimator lens 22f (see FIG. 3). The XY alignment target projection optical system 22 shares the half mirror 21e with the anterior eye observation optical system 21.

[0038] XY alignment light source 22a emits infrared light. Collimator lens 22f is disposed on the optical path of XY alignment target projection optical system 22 so that its focal point coincides with pinhole plate 22d. The infrared light emitted from XY alignment light source 22a is focused by condenser lens 22b, passes through aperture stop 22c, and is guided to the hole in pinhole plate 22d.

[0039] The infrared light that passes through the hole in the pinhole plate 22d is reflected by the dichroic mirror 22e. The infrared light is then incident on the half mirror 21g and guided to the collimator lens 22f, where it is converted into parallel light and then emitted from the collimator lens 22f to the half mirror 21e. This parallel infrared light is reflected by the half mirror 21e and travels along the optical axis O1 of the anterior-segment observation optical system 21. As a result, the parallel infrared light passes through the half mirror 21g and the chamber window glass 21d, and then passes through the inside of the nozzle 21b, to be incident on the subject's eye E as XY alignment index light.

[0040] Although not shown, the XY alignment index light incident on the subject's eye E is reflected by the surface of the cornea Ec to form an XY spot. The aperture stop 22c is provided at a position conjugate with the corneal apex Ep of the cornea Ec with respect to the collimator lens 22f.

[0041] The fixation target projection optical system 23 projects a fixation target onto the subject's eye E. The fixation target projection optical system 23 has a fixation target light source 23a and a pinhole plate 23b (see FIG. 3). The fixation target projection optical system 23 also shares a dichroic mirror 22e and a collimator lens 22f with the XY alignment target projection optical system 22, and also shares a half mirror 21e with the anterior eye observation optical system 21.

[0042] The fixation target light source 23a emits visible light as fixation target light. This fixation target light is guided to the hole in the pinhole plate 23b, passes through the hole in the pinhole plate 23b and the dichroic mirror 22e, and is then emitted to the collimator lens 22f. The fixation target light is then converted into approximately parallel light by the collimator lens 22f and emitted toward the half mirror 21e. After being reflected by the half mirror 21e, the light travels along the optical axis O1 of the anterior eye observation optical system 21. As a result, the fixation target light passes through the half mirror 21g and the chamber window glass 21d, then passes through the inside of the nozzle 21b, and reaches the subject's eye E. By having the subject gaze at this fixation target as a fixation target, the subject's line of sight can be fixed.

[0043] The applanation detection optical system 24 (see FIG. 3) receives the XY index reflected light and outputs an applanation signal (also called a corneal deformation signal) which is a light-receiving signal indicating the amount of the XY index reflected light. The applanation detection optical system 24 has a lens 24a, a pinhole plate 24b, and a light-receiving sensor 24c, and also shares the half mirror 21g with the anterior-segment observation optical system 21.

[0044] When the surface of the cornea Ec is flat, the lens 24a focuses the XY index reflected light onto the opening of the pinhole plate 24b, which is provided at the focal position of the lens 24a.

[0045] The light receiving sensor 24c is, for example, a photodiode that outputs an applanation signal corresponding to the amount of light received from the reflected XY index light. The light receiving sensor 24c outputs the applanation signal to the control device 16.

[0046] The XY index reflected light passes through the inside of the nozzle 21b, passes through the chamber window glass 21d, and reaches the half mirror 21g. A part of the XY index reflected light is reflected by the half mirror 21g, passes through the lens 24a, and then enters the pinhole plate 24b.

[0047] When the surface of the cornea Ec is flattened (also called a flattened state) by the air blown from the nozzle 21b, the applanation detection optical system 24 allows the entire XY index reflected light that has traveled to the applanation detection optical system 24 to reach the light receiving sensor 24c through the pinhole plate 24b. When the cornea Ec is in a state other than the applanation state, the applanation detection optical system 24 allows the XY index reflected light to reach the light receiving sensor 24c while partially blocking it with the pinhole plate 24b. Therefore, the signal intensity of the applanation signal output from the applanation detection optical system 24 gradually increases as the surface of the cornea Ec changes from a convex state to an applanated state, and further gradually decreases as the surface changes from an applanated state to a concave state. decreases to.

[0048] The Z-alignment index projection optical system 25 (see FIG. 2) projects Z-alignment index light for Z-alignment in the Z direction onto the cornea Ec from an oblique direction. The Z-alignment index projection optical system 25 includes, along an optical axis O2, a Z-alignment light source 25a, a condenser lens 25b, an aperture stop 25c, a pinhole plate 25d, and a collimator lens 25e.

[0049] Z-alignment light source 25a emits infrared light (for example, a wavelength of 860 nm). Aperture stop 25c is provided at a position conjugate with corneal vertex Ep with respect to collimator lens 25e. Collimator lens 25e is positioned so as to focus on the hole in pinhole plate 25d.

[0050] The infrared light emitted from the Z-alignment light source 25a is condensed by the condenser lens 25b, passes through the aperture stop 25c, and travels to the pinhole plate 25d. The infrared light that passes through the hole in the pinhole plate 25d is collimated by the collimator lens 25e, and then enters the subject's eye E as Z-alignment index light. The light is reflected by the cornea Ec to form a bright spot image on the subject's eye E.

[0051] The Z alignment detection optical system 26 receives the Z alignment index light reflected by the cornea Ec (hereinafter referred to as Z index reflected light) and detects the positional relationship in the Z direction between the measurement head 14 and the cornea Ec. The Z alignment detection optical system 26 has an imaging lens 26a, a cylindrical lens 26b, and a light receiving sensor 26c along the optical axis O3.

[0052] The cylindrical lens 26b has power in the Y direction. The light receiving sensor 26c is a sensor capable of detecting the light receiving position of the Z index reflected light on its light receiving surface, and may be, for example, a line sensor or a PSD (Position Sensitive Detector).

[0053] The Z index reflected light is focused by the imaging lens 26a and then travels to the cylindrical lens 26b, where it is focused in the Y direction to form a bright spot image on the light receiving sensor 26c.

[0054] The light-receiving sensor 26c is positioned conjugately with the bright spot image formed on the subject's eye E by the Z alignment target projection optical system 25 with respect to the imaging lens 26a in the XZ plane. Furthermore, the light-receiving sensor 26c is positioned conjugately with the corneal apex Ep with respect to the imaging lens 26a and the cylindrical lens 26b in the YZ plane. That is, since the light-receiving sensor 26c is conjugate with the aperture stop 25c, even if the cornea Ec shifts in the Y direction, the Z target reflected light from the surface of the cornea Ec efficiently enters the light-receiving sensor 26c. The light-receiving sensor 26c then outputs a detection signal (hereinafter referred to as a Z detection signal) of the Z target reflected light collected by the cylindrical lens 26b to the control device 16. This Z detection signal indicates the relative position of the subject's eye E in the Z direction with respect to the measurement head 14, more specifically, the distance in the Z direction between the measurement head 14 and the subject's eye E (corneal apex Ep). This allows Z alignment detection.

[0055] The spray mechanism 34 (see FIG. 3) has, in addition to the nozzle 21b already described, a chamber 34a, a glass plate 34b, a pressure sensor 34c, a cylinder 34d, a communication pipe 34e, a piston 34f, and a solenoid 34g.

[0056] The nozzle 21b is attached to the chamber 34a via a transparent glass plate 34b. A chamber window 34b is also provided in the chamber 34a at a position opposite the nozzle 21b. Glass 21d is provided in chamber 34a. Furthermore, a pressure sensor 34c, which will be described later, is provided in chamber 34a.

[0057] The cylinder 34d is connected to the chamber 34a via a communication pipe 34e. This allows the interior of the cylinder 34d to communicate with the interior of the chamber 34a via the communication pipe 34e, thereby connecting the interior of the cylinder 34d to the nozzle 21b. A piston 34f is movably provided inside the cylinder 34d. The cylinder 34d and piston 34f form an air compression chamber.

[0058] The solenoid 34g is, for example, a rotary solenoid. The solenoid 34g is an electric actuator that moves a piston 34f inside a cylinder 34d. The solenoid 34g is operated by receiving a current from a drive current supply unit 40, and compresses the air inside the cylinder 34d by linearly moving the piston 34f inside the cylinder 34d. This causes air to be blown onto the cornea Ec from the nozzle 21b via the communicating tube 34e and the chamber 34a.

[0059] The drive current supply unit 40, which will be described in detail later, supplies current to the solenoid 34g under the control of the control device 16 to operate the solenoid 34g.

[0060] The pressure sensor 34c outputs a pressure signal indicating the pressure inside the chamber 34a and the pressure inside the cylinder 34d that communicates with the chamber 34a.

[0061] [Configuration of drive current supply unit 40] Fig. 4 is a schematic diagram of the drive current supply unit 40. As shown in Fig. 4, the drive current supply unit 40 includes a power supply 42, a load switch IC (Integrated Circuit) 44, a connection point 45, a capacitor 46, and a solenoid drive circuit 48.

[0062] The power supply 42 has, for example, an output voltage of 24 V and an output power of 100 W. When a trigger signal output from a solenoid drive circuit 48 (described later) is OFF, the power supply 42 charges a capacitor 46 via a load switch IC 44 (described later) and a connection point 45. When a trigger signal output from a solenoid drive circuit 48 (described later) is ON, the power supply 42 supplies a drive current I1 (corresponding to a second drive current of the present invention) to the solenoid 34g via the load switch IC 44 and the connection point 45. This allows the solenoid drive circuit 48 to selectively charge the capacitor 46 and supply the drive current I1 to the solenoid 34g.

[0063] One end of the load switch IC 44 is electrically connected to the power supply 42, and the other end is electrically connected to the capacitor 46 and the solenoid drive circuit 48 via a connection point 45. The load switch IC 44 switches the electrical connection between the power supply 42 and the connection point 45 (the capacitor 46 or the solenoid 34g) between ON and OFF.

[0064] The load switch IC 44 also functions as a current limiting circuit of the present invention, performing current control to limit the charging current IA supplied from the power supply 42 to the capacitor 46 when the capacitor 46 is being charged, and the drive current I1 supplied from the power supply 42 to the solenoid 34g when the solenoid 34g is operating. Note that "limiting" the charging current IA and the drive current I1 means reducing the magnitude of the charging current IA and the drive current I1, or setting an upper limit on the magnitude of the charging current IA and the drive current I1. The "limiting" of the charging current IA and the drive current I1 by the load switch IC 44 is achieved by a well-known inrush current suppression function possessed by the load switch IC 44. This allows the capacitor 46 to be charged with a soft start, and suppresses the occurrence of an inrush current when the capacitor 46 starts to charge.

[0065] The connection point 45 connects the load switch IC 44, the capacitor 46, and the solenoid drive circuit 48.

[0066] The capacitor 46 switches between a charged state and a discharged state depending on whether a trigger signal output from a solenoid drive circuit 48 (described later) is ON or OFF. The capacitor 46 is in a charged state when the trigger signal output from the solenoid drive circuit 48 is OFF. The capacitor 46 is in a discharged state when the trigger signal output from the solenoid drive circuit 48 is ON.

[0067] In the charging state, the capacitor 46 is soft-start charged by the power supply 42 via the load switch IC 44 and the connection point 45, and accumulates electric charge through this charging. In the discharging state, the capacitor 46 discharges the electric charge accumulated through charging, thereby supplying a drive current I2 (corresponding to the first drive current of the present invention) to the solenoid 34g via the connection point 45.

[0068] The solenoid drive circuit 48 corresponds to the current supply switching control unit of the present invention and controls the operation of the drive current supply unit 40. The solenoid drive circuit 48 is electrically connected to the load switch IC 44 and the capacitor 46 via a connection point 45, and is also electrically connected to the solenoid 34g. Under the control of the control device 16 (described later), the solenoid drive circuit 48 switches the output of a trigger signal between ON and OFF, thereby switching the charge / discharge state of the capacitor 46 and switching ON / OFF the current supply to the solenoid 34g.

[0069] When the trigger signal output from the solenoid drive circuit 48 is OFF, the drive current supply unit 40 switches to the capacitor charging circuit. The capacitor charging circuit is a circuit that electrically connects only the capacitor 46 to the load switch IC 44 (power supply 42) that is in the ON state. This allows the power supply 42 and the load switch IC 44 to charge the capacitor 46 in a soft start.

[0070] When the trigger signal output from the solenoid drive circuit 48 is ON, the drive current supply unit 40 switches to the solenoid operation circuit. The solenoid operation circuit is a circuit that can supply current to the solenoid 34g from both the load switch IC 44 (power supply 42) in the ON state and the capacitor 46. As a result, a drive current I1 is supplied from the power supply 42 to the solenoid drive circuit 48 via the load switch IC 44 and connection point 45. At the same time, the capacitor 46 discharges the charge it has accumulated through charging, and a drive current I2 is supplied from this capacitor 46 to the solenoid drive circuit 48 via the connection point 45.

[0071] The solenoid drive circuit 48 then outputs to the solenoid 34g the drive currents I1 and I2 supplied from the power supply 42 and the capacitor 46. As a result, the solenoid 34g operates in response to the supply of both the drive currents I1 and I2, causing the piston 34f to move linearly inside the cylinder 34d.

[0072] Fig. 5 is a functional block diagram of the control device 16. As shown in Fig. 5, the control device 16 is connected to the above-mentioned movement mechanism 13, the monitor 15, the optical systems 21 to 26 in the measurement head 14, the spray mechanism 34, and the drive current supply unit 40 (solenoid drive circuit 48). The control device 16 comprehensively controls the operation of the non-contact tonometer 10, including these units.

[0073] The control device 16 includes an arithmetic circuit configured with various processors, memories, etc. The various processors include a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device)). ), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays). The various functions of the control device 16 may be realized by one processor, or may be realized by multiple processors of the same type or different types.

[0074] The control device 16 reads and executes a control program (not shown) to function as an alignment control unit 50, a measurement control unit 52, and an intraocular pressure value calculation unit 54. Note that what is described as a "unit" of the control device 16 may also be a "circuit," a "device," or a "instrument." In other words, what is described as a "unit" may be composed of firmware, software, hardware, or a combination of these.

[0075] The alignment control unit 50 operates when measuring the intraocular pressure of the subject's eye E, and controls automatic alignment of the measurement head 14 with respect to the subject's eye E in the X, Y, and Z directions.

[0076] Specifically, the alignment control unit 50 controls the anterior eye observation optical system 21 and the XY alignment target projection optical system 22 described above to perform XY alignment detection, which detects the relative position of the subject's eye E in the XY directions with respect to the measurement head 14. The alignment control unit 50 also controls the Z alignment target projection optical system 25 and the Z alignment detection optical system 26 to perform Z alignment detection, which detects the relative position of the subject's eye E in the Z direction with respect to the measurement head 14. Note that the XY alignment detection and Z alignment detection of the non-contact tonometer 10 are well-known techniques, so a detailed description thereof will be omitted here. Next, the alignment control unit 50 drives the moving mechanism 13 based on the XYZ alignment detection result to perform automatic alignment of the measurement head 14 with respect to the subject's eye E in the XYZ directions.

[0077] The measurement control unit 52 turns off the output of the trigger signal from the solenoid drive circuit 48 from the time the non-contact tonometer 10 is started until auto-alignment is completed. This causes the drive current supply unit 40 to switch to the capacitor charging circuit, and the power supply 42 and the load switch IC 44 charge the capacitor 46 with a soft start.

[0078] FIG. 6 is a diagram showing the applanation signal (see symbol H1) output from the applanation detection optical system 24, the pressure signal (see symbol H2) output from the pressure sensor 34c, the ON / OFF state of the trigger signal output from the solenoid drive circuit 48, the charge / discharge state of the capacitor 46, and the current output from the power supply 42 after auto-alignment is completed (t=t0).

[0079] 6, when auto-alignment is completed (t=t0), the measurement control unit 52 turns on the output of a trigger signal from the solenoid drive circuit 48. In addition, the measurement control unit 52 continuously executes the following processes: projection of XY alignment target light onto the cornea Ec by the XY alignment target projection optical system 22; reception of the XY target reflected light by the applanation detection optical system 24 and output of an applanation signal (reference symbol H1); and measurement of the pressure inside the chamber 34a and the piston 34f by the pressure sensor 34c and output of a pressure signal (reference symbol H2).

[0080] When the trigger signal output from the solenoid drive circuit 48 is turned ON, the drive current supply unit 40 switches to the solenoid operating circuit, and a drive current I1 is supplied from the power supply 42 and load switch IC 44 to the solenoid 34g via the solenoid drive circuit 48 and other components. At the same time, the capacitor 46 enters a discharge state, and a drive current I2 is supplied from the capacitor 46 to the solenoid 34g via the solenoid drive circuit 48 and other components. This causes the solenoid 34g to operate in response to the supply of drive currents I1 and I2, causing the piston 34f to move linearly within the cylinder 34d. As a result, the piston 34f compresses the air in the chamber 34a, starting the spraying process of blowing air onto the cornea Ec from the nozzle 21b.

[0081] In this embodiment, the power supply 42 and the load switch IC 44 are connected to the solenoid 34g. The supplied drive current I1 is 3 A, and the drive current I2 supplied from capacitor 46 to solenoid 34g is 5 A, with the total current supplied to solenoid 34g being 8 A. By making the drive currents I1 and I2 different in magnitude and further making drive current I1 smaller than drive current I2, the power capacity of power supply 42 can be further reduced. As a result, the power supply 42 can be made smaller and less expensive.

[0082] The ratio of drive current I1 to drive current I2 is not particularly limited, and may be set to (3.5:6.5) to (4.5:5.5) if the total is "10". Furthermore, the ratio of drive current I1 to drive current I2 may be set to "5:5". The ratio of drive current I1 to drive current I2 can also be set to "10:0" or "0:10" as needed.

[0083] After the start of the spraying process, the measurement control unit 52 switches the output of the trigger signal from the solenoid drive circuit 48 from ON to OFF at a predetermined or arbitrary timing (t=t1) after the peak of the applanation signal (applanation waveform) output from the applanation detection optical system 24 is detected. Note that the period ΔTA from time t0 to time t1 is the period during which current is supplied from the power supply 42 to the solenoid 34g.

[0084] When the output of the trigger signal from the solenoid drive circuit 48 is turned OFF, the capacitor 46 enters a charging state, and is recharged by the power supply 42 and the load switch IC 44. The period ΔTB from time t1 to time t2 when the recharging of the capacitor 46 is completed is the recharging period of the capacitor 46. The measurement control unit 52 prohibits the execution of the next spraying process (intraocular pressure measurement) until the period ΔTB has elapsed, that is, until the recharging of the capacitor 46 is completed.

[0085] Returning to FIG. 5, the intraocular pressure value calculation unit 54 calculates the intraocular pressure value of the subject's eye E based on the applanation signal continuously output from the applanation detection optical system 24 and the pressure signal continuously output from the pressure sensor 34c.

[0086] For example, the intraocular pressure value calculation unit 54 calculates the centroid position (or peak position) of the applanation waveform based on the applanation signal. Next, the intraocular pressure value calculation unit 54 calculates a pressure signal corresponding to the centroid position of the applanation waveform based on the calculation result of the centroid position of the applanation waveform and the waveform of the pressure signal, and converts this pressure signal into a pressure value. Then, the intraocular pressure value calculation unit 54 calculates the intraocular pressure value of the subject's eye E based on the pressure value corresponding to the centroid position of the applanation waveform. Note that the method of calculating the intraocular pressure value of the subject's eye E by the intraocular pressure value calculation unit 54 is not limited to the above-mentioned method, and various known methods can be used.

[0087] [Function of non-contact tonometer 10] 7 is a flowchart showing the flow of the intraocular pressure measurement process of the subject's eye E using the non-contact tonometer 10 configured as described above. As shown in FIG. 7, after the non-contact tonometer 10 is started up, the control device 16 functions as an alignment control unit 50, a measurement control unit 52, and an intraocular pressure value calculation unit 54.

[0088] When the non-contact tonometer 10 is started up, the trigger signal output from the solenoid drive circuit 48 is turned off, and the drive current supply unit 40 switches to the capacitor charging circuit. This causes the capacitor 46 to enter a charging state, and an electric charge is accumulated in the capacitor 46 (step S1). At this time, the load switch IC 44 is used to charge the capacitor 46 with a soft start, thereby suppressing the occurrence of an inrush current when charging of the capacitor 46 begins. As a result, damage to electronic components such as the capacitor 46 is prevented.

[0089] When the examiner inputs a measurement start operation to the non-contact tonometer 10, the alignment control unit 5 0 controls the anterior-segment observation optical system 21 and the XY alignment target projection optical system 22 to perform XY alignment detection, and also controls the Z alignment target projection optical system 25 and the Z alignment detection optical system 26 to perform Z alignment detection. Next, the alignment control unit 50 drives the moving mechanism 13 based on the XYZ alignment detection result to perform auto-alignment of the measuring head 14 in the X, Y and Z directions with respect to the subject's eye E (step S2).

[0090] When the auto-alignment is completed, the measurement control unit 52 turns on the output of the trigger signal from the solenoid driving circuit 48 (step S3), which switches the driving current supply unit 40 to the solenoid operating circuit.

[0091] When the drive current supply unit 40 switches to the solenoid operation circuit, a drive current I1 is supplied from the power supply 42 and the load switch IC 44 to the solenoid drive circuit 48. At the same time, the capacitor 46 enters a discharge state and discharges the accumulated charge, thereby supplying a drive current I2 from the capacitor 46 to the solenoid drive circuit 48. As a result, the solenoid drive circuit 48 starts to supply the drive currents I1 and I2 to the solenoid 34g (step S4).

[0092] When the solenoid 34g is actuated by the supply of the drive currents I1 and I2, the piston 34f is moved linearly within the cylinder 34d by the solenoid 34g, compressing the air in the chamber 34a. As a result, a spraying process is initiated in which air is sprayed onto the cornea Ec from the nozzle 21b (step S5). Because current is supplied to the solenoid 34g from both the power supply 42 and the capacitor 46, there is no need to increase the capacitance of the capacitor 46 as in the conventional case, and the capacitance of the capacitor 46 can be reduced. As a result, the power capacity of the power supply 42 can be reduced, allowing the use of a compact power supply 42 with a small power capacity.

[0093] During the spraying process, the measurement control unit 52 also continuously controls the XY alignment index projection optical system 22 to project the XY alignment index light onto the cornea Ec, the applanation detection optical system 24 to receive the XY index reflected light and output an applanation signal, and the pressure sensor 34c to measure the pressure inside the piston 34f and output a pressure signal (step S6).

[0094] When the measurement control unit 52 detects a peak of the applanation signal (applanation waveform) output from the applanation detection optical system 24 after the start of the spraying process, it switches the output of the trigger signal from the solenoid drive circuit 48 from ON to OFF at a predetermined or arbitrary timing after the peak detection (step S7).

[0095] When the trigger signal output from the solenoid drive circuit 48 is turned OFF, the drive current supply unit 40 switches to the capacitor charging circuit. This stops the supply of drive currents I1 and I2 to the solenoid 34g (step S8). At the same time, the capacitor 46 enters a charging state, and the power supply 42 and the load switch IC 44 recharge the capacitor 46 in a soft start (step S9).

[0096] When the spraying process is completed, the intraocular pressure value calculation unit 54 calculates the intraocular pressure value of the subject's eye E using a known method based on the applanation signal output from the applanation detection optical system 24 and the pressure signal output from the pressure sensor 34c, and displays the calculation result of the intraocular pressure value on the monitor 15 (step S10).

[0097] As described above, in the non-contact tonometer 10 of this embodiment, current is supplied to the solenoid 34g from both the power supply 42 and the capacitor 46, so that the capacitance of the capacitor 46 and the power capacity and size of the power supply 42 can be reduced. This will enable cost reduction and miniaturization of the 0.

[0098] [others] In the above embodiment, the solenoid 34g is used as an example of the electric actuator that moves the piston 34f inside the cylinder 34d, but other known electric actuators may be used instead of the solenoid 34g.

[0099] In the above embodiment, the currents supplied from the power supply 42 to the capacitor 46 and the solenoid 34g are limited by the load switch IC 44, but a known current limiting (control) circuit may be used instead of the load switch IC 44 as long as it is possible to limit each current.

[0100] In the above embodiment, an example of a circuit configuration capable of supplying current to the solenoid 34g from both the power supply 42 and the capacitor 46 is shown in FIG. 4, but this circuit configuration can be modified as appropriate. [Explanation of symbols]

[0101] 10. Non-contact tonometer 11...Bass 12...Face support part 12a...Chin rest 12b...Forehead support 12c…post 13...Movement mechanism 14...Measuring head 15...Monitor 16...Control device 21...Anterior segment observation optical system 21a...Anterior segment illumination light source 21b...Nozzle 21c...Anterior window glass 21d...Chamber window glass 21e...Half mirror 21f...Objective lens 21g...Half mirror 21i...image sensor 22...XY alignment index projection optical system 22a...XY alignment light source 22b...Condenser lens 22c...Aperture stop 22d...Pinhole plate 22e…Dichroic mirror 22f...Collimator lens 23…Fixation target projection optical system 23a...Fixation target light source 23b...Pinhole plate 24...Applanation detection optical system 24a...Lens 24b...Pinhole plate 24c...Light receiving sensor 25...Z alignment index projection optical system 25a...Z alignment light source 25b...Condenser lens 25c...Aperture 25d...Pinhole plate 25e...Collimator lens 26...Z alignment detection optical system 26a...Imaging lens 26b...Cylindrical lens 26c...Light receiving sensor 34...Spraying mechanism 34a...Chamber 34b...glass plate 34c...Pressure sensor 34d...cylinder 34e…Communication pipe 34f...piston 34g...Solenoid 40...Drive current supply unit 42…Power supply 44...Load switch IC 45...Connection point 46...Capacitor 48...Solenoid drive circuit 50...Alignment control unit 52...Measurement control section 54...Intraocular pressure value calculation unit E: Eye to be examined Ec…cornea Ep…corneal apex I1: Drive current I2: Drive current IA…Charging current O1~O3...Optical axis ΔTA, ΔTB…period

Claims

1. A cylinder; a piston movably provided inside the cylinder; an electric actuator that moves the piston inside the cylinder to compress the air inside the cylinder with the piston; a nozzle communicating with the inside of the cylinder and blowing the air compressed by the piston onto the subject's eye; a capacitor that discharges charges accumulated by charging to supply a first drive current to the electric actuator; a power source capable of charging the capacitor and supplying a second drive current to the electric actuator; Equipped with The non-contact tonometer is configured such that the electric actuator operates by receiving both the first drive current from the capacitor and the second drive current from the power supply.

2. 2. The non-contact tonometer according to claim 1, further comprising a current limiting circuit that limits a charging current supplied from the power supply to the capacitor and a second drive current supplied from the power supply to the electric actuator.

3. The non-contact tonometer according to claim 2 , wherein the current limiting circuit is a load switch.

4. The non-contact tonometer according to claim 1 , further comprising a current supply switching control unit that switches ON and OFF the supply of the first drive current and the second drive current to the electric actuator.

5. 5. The non-contact tonometer according to claim 4, wherein the power supply charges the capacitor when the current supply switching control unit switches the supply of the first drive current and the second drive current to the electric actuator from ON to OFF.

6. The non-contact tonometer according to claim 1 , wherein the magnitude of the first drive current is different from the magnitude of the second drive current.

7. The non-contact tonometer according to claim 4 , wherein the current supply switching control unit selectively charges the capacitor with the power supply and supplies a second drive current from the power supply to the electric actuator.

8. 8. The non-contact tonometer according to claim 1, wherein the electric actuator is a solenoid.

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