Piston unit and non-contact tonometer

Abstract

To provide a piston unit and a non-contact tonometer that can reduce operating noise while ensuring performance. [Solution] A piston unit 1 for a non-contact tonometer used to measure the intraocular pressure of an eye under examination comprises a cylinder 42 that delivers fluid to a nozzle that sprays fluid onto the cornea of ​​the eye under examination via an internal piston 44, a solenoid 45 having a rotating arm 45a, a link joint 48 that connects a first point 45b of the arm 45a to the piston 44, and a stopper 49 that receives a second point 45c of the rotating arm 45a.

Description

Technical Field

[0001] The present disclosure relates to a piston unit and a non-contact tonometer used for measuring the intraocular pressure of an eye to be examined.

Background Art

[0002] Conventionally, a non-contact tonometer that measures the intraocular pressure value of an eye to be examined without contacting the cornea by blowing compressed air (fluid) from a nozzle toward the cornea of the eye to be examined to deform the cornea and detecting the deformed state thereof is known. The non-contact tonometer irradiates the cornea with an index light in accordance with the blowing of compressed air onto the cornea by the nozzle, detects the amount of light of the reflected light of the index light reflected by the cornea, and calculates the intraocular pressure value of the eye to be examined based on the amount of light of the reflected light and the air pressure when the deformed state of the cornea becomes a flattened state (applanated state).

[0003] Patent Document 1 discloses a non-contact tonometer configured such that the air inside a cylinder connected to a nozzle is compressed and air is discharged from the nozzle by the movement of a piston inside the cylinder. In the non-contact tonometer disclosed in Patent Document 1, the piston is connected to a solenoid via a drive lever, and the rotational movement of the solenoid is converted into a linear movement via the drive lever, whereby the piston moves inside the cylinder.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, non-contact tonometers, as mentioned above, are required to be able to measure the intraocular pressure of the eye being examined, from low intraocular pressure to high intraocular pressure caused by disease. On the other hand, when measuring the intraocular pressure of an eye being examined, the amount of air required for flattening is small, so it is necessary to adjust the amount or speed of movement of the piston within the cylinder in order to avoid discharging unnecessary air and causing discomfort to the subject. In this regard, Patent Document 1 adjusts the amount of movement of the piston within the cylinder by configuring the aforementioned piston with an air-pushing part located on the nozzle side and a piston drive part connected to a drive lever independently of the air-pushing part.

[0006] However, in the non-contact tonometer disclosed in Patent Document 1, as mentioned above, the air-extrusion unit and the piston drive unit are separated, so a loud impact noise is generated when the two come into contact. For this reason, although a cushioning material is attached to the air-extrusion unit in Patent Document 1, because the piston drive unit moves in a linear motion, the kinetic energy of the piston drive unit is quickly converted into energy that causes the impact noise, and the aforementioned impact noise cannot be sufficiently suppressed. Thus, in conventional non-contact tonometers, including Patent Document 1, it has been difficult to suppress operating noise (especially impact noise) while ensuring performance.

[0007] This disclosure is made in view of these circumstances and aims to provide a piston unit and a non-contact tonometer that can reduce operating noise while ensuring performance. [Means for solving the problem]

[0008] One embodiment of the piston unit of the present disclosure is a piston unit for a non-contact tonometer used for measuring the intraocular pressure of an eye under examination, comprising: a cylinder that delivers fluid to a nozzle that sprays fluid onto the cornea of ​​the eye under examination by an internal piston; a drive unit having a rotating arm; a connecting part that connects a first location of the arm to the piston; and a stopper that receives a second location of the rotating arm.

[0009] Furthermore, one embodiment of the non-contact tonometer of the present disclosure is a non-contact tonometer used for measuring the intraocular pressure of an eye under examination, which has the piston unit described above and is equipped with a spraying mechanism that sprays fluid from a nozzle onto the cornea of ​​the eye under examination. [Effects of the Invention]

[0010] The piston unit and non-contact tonometer of this disclosure make it possible to reduce operating noise while ensuring performance. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view of a non-contact tonometer according to the first embodiment of the present disclosure. [Figure 2] Figure 1 is a schematic top view of the multiple types of optical systems within the measurement head, as seen from above. [Figure 3] Figure 1 is a schematic side view of the various optical systems within the measurement head, as seen from the side. [Figure 4] This is a schematic cross-sectional perspective view of the spraying mechanism, including the piston unit, as seen from above. [Figure 5] Figure 4 is a schematic perspective view of the piston unit as seen from above. [Figure 6] Figure 4 is a schematic diagram of the piston unit as seen from above, showing the configuration when the piston is in its initial position. [Figure 7] Figure 4 is a schematic diagram of the piston unit as seen from above, showing the configuration when the piston is in the final compression position. [Figure 8] Figure 4 is a schematic cross-sectional view of the piston unit as seen from the side, showing the configuration when the piston is in its initial position. [Figure 9] Figure 4 is a schematic cross-sectional view of the piston unit as seen from the side, showing the configuration when the piston is in the compression start position. [Figure 10] Figure 4 is a schematic cross-sectional view of the piston unit as seen from the side, showing the configuration when the piston is in the final compression position. [Figure 11] It is a schematic enlarged cross-sectional view showing the gap between the end of the link bar and the joint in the link joint shown in FIG. 4. [Figure 12] It is a schematic perspective view seen from above of the piston unit of the non-contact tonometer according to the second embodiment of the present disclosure. [Figure 13] It is a figure for comparing the magnitude of the rotational energy in the non-contact tonometer according to the first embodiment and the non-contact tonometer according to the second embodiment. [Embodiments for Carrying Out the Invention]

[0012] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, a detailed description of already well-known matters or a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art. In addition, the attached drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and it is not intended to limit the subject matter described in the claims by these.

[0013] [First Embodiment] FIG. 1 is a side view of a non-contact tonometer 10 according to the first embodiment of the present disclosure. As shown in FIG. 1, the non-contact tonometer 10 non-contact measures the intraocular pressure value of the test eye E. This non-contact tonometer 10 includes a base 11, a face support portion 12, a moving mechanism 13, a measurement head 14, a monitor 15, and a control device 16.

[0014] Among the XYZ directions (three-axis directions) orthogonal to each other in the figure, the Y direction is the vertical direction, the Z direction is the front-rear direction (also referred to as the operating distance direction) in which the subject (test eye E) approaches or moves away, and the X direction is the left-right direction perpendicular to both the vertical direction and the front-rear direction. Also, among the Z directions (front-rear directions), the side approaching the test eye E (subject) is referred to as the front side in the Z direction, and the side moving away from the test eye E (subject) is referred to as the rear side in the Z direction.

[0015] A face support section 12 and a movement mechanism 13 are provided on the base 11, extending from the front side in the Z direction to the rear side in the Z direction.

[0016] The face support section 12 is fixed to the base 11. This face support section 12 comprises a chin rest 12a that receives the subject's chin, a forehead rest 12b that the subject's forehead contacts, and a pair of support columns 12c that support the forehead rest 12b, and supports the subject's face.

[0017] The moving mechanism 13 holds the measuring head 14 so that it can move in the XYZ directions.

[0018] The measuring head 14 measures the intraocular pressure value of the eye E in a non-contact manner by deforming the cornea Ec (see Figure 2) of the eye E by blowing air from the nozzle 21b toward the cornea Ec (see Figure 2) and detecting the state of deformation.

[0019] The monitor 15 is, for example, a touch panel monitor and is mounted on the back side of the measurement head 14. Under the control of the control device 16 described later, the monitor 15 displays various images, including the captured image (observation image) of the eye E taken by the measurement head 14, the measurement result of the intraocular pressure value of the eye E, and a menu screen for performing various operations and settings.

[0020] The control device 16 is connected to the aforementioned moving mechanism 13, measuring head 14, and monitor 15, etc. This control device 16 controls the auto-alignment of the measuring head 14 to the eye under examination E, the measurement of intraocular pressure of the eye under examination E by the measuring head 14, and calculates the intraocular pressure value of the eye under examination E.

[0021] (optical system) Figure 2 is a schematic top view of the multiple types of optical systems within the measuring head 14 shown in Figure 1, viewed from above (Y direction). Figure 3 is a schematic side view of the multiple types of optical systems within the measuring head 14 shown in Figure 1, viewed from the side (X direction).

[0022] 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, and a Z alignment detection optical system 26.

[0023] The anterior segment observation optical system 21 is used for observing the anterior segment of the eye E under examination and for XY alignment of the measurement head 14 in the XY direction relative to the eye E under examination. This anterior segment observation optical system 21 is equipped with an anterior segment illumination light source 21a (see Figure 2). On the optical axis O1 (the principal optical axis of the non-contact tonometer 10) of the anterior segment observation optical system 21, there is an air blowing nozzle 21b, an anterior segment window glass 21c (see Figure 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.

[0024] Multiple anterior segment illumination light sources 21a are provided around the anterior segment window glass 21c to directly illuminate the anterior segment of the eye E under examination.

[0025] The nozzle 21b is connected to the chamber 41 (see Figure 3) of the spraying mechanism 40 and blows air onto the anterior segment (cornea Ec) of the eye E under examination.

[0026] The image of the anterior segment of the eye E under examination (image light from the anterior segment) passes outside the nozzle 21b, through the anterior segment window glass 21c, the glass plate 46 (described later), the chamber window glass 21d, the half mirror 21g, and the half mirror 21e, and is formed on the light-receiving surface of the image sensor 21i by the objective lens 21f.

[0027] The image sensor 21i is, for example, a CCD (Charge Coupled Device) or CMOS (complementary metal oxide semiconductor) type image sensor. This image sensor 21i captures an image of the anterior segment of the eye that is incident on its light-receiving surface, generates an imaging signal, and outputs this imaging signal to the control device 16. As a result, under the control of the control device 16, the observed image D of the anterior segment of the eye E under examination, based on the imaging signal output from the image sensor 21i, is displayed on the monitor 15.

[0028] Furthermore, the anterior segment observation optical system 21 guides the reflected light from the cornea Ec of the XY alignment index light projected onto the eye E by the XY alignment index projection optical system 22 (described later) 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 onto the light-receiving surface of the image sensor 21i by the objective lens 21f. As a result, a bright spot image is formed on the light-receiving surface of the image sensor 21i at a position corresponding to the XY positional relationship (relative position) between the measurement head 14 and the cornea Ec.

[0029] The image sensor 21i captures a bright spot image formed on its light-receiving surface and outputs the imaging signal of this bright spot image to the control device 16. As a result, under the control of the control device 16, the observation image D of the anterior segment and the bright spot image are superimposed on the monitor 15. Alignment assist marks are also displayed on the monitor 15.

[0030] The XY alignment index projection optical system 22 projects XY alignment index light onto the cornea Ec of the eye under examination E from the front. This XY alignment index light is used for XY alignment of the measurement head 14 with respect to the anterior segment of the eye under examination E. The XY alignment index light is also used to measure the intraocular pressure value of the eye under examination E. Hereinafter, the reflected light of the XY alignment index light from the cornea Ec will be simply referred to as "XY index reflected light".

[0031] The XY alignment indicator projection optical system 22 includes an XY alignment light source 22a, a focusing lens 22b, an aperture diaphragm 22c, a pinhole plate 22d, a dichroic mirror 22e, and a collimator lens 22f (see Figure 3). The XY alignment indicator projection optical system 22 shares a half mirror 21e with the anterior segment observation optical system 21.

[0032] The XY alignment light source 22a emits infrared light. The collimator lens 22f is positioned on the optical path of the XY alignment index projection optical system 22 so that its focal point coincides with the pinhole plate 22d. In this XY alignment index projection optical system 22, the infrared light emitted from the XY alignment light source 22a is focused by the condensing lens 22b, passes through the aperture diaphragm 22c, and is guided to the hole in the pinhole plate 22d.

[0033] Infrared light passing through the hole in the pinhole plate 22d is reflected by the dichroic mirror 22e and guided to the collimator lens 22f, where it is further made into parallel light before being emitted from the collimator lens 22f to the half mirror 21e. This parallel infrared light is reflected by the half mirror 21e and then 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 inside the nozzle 21b, entering the eye under examination E as XY alignment indicator light.

[0034] The XY alignment indicator light incident on the eye E under examination is reflected off the corneal surface Ec, forming a bright spot image (though this is not shown in the illustration). The aperture diaphragm 22c is positioned conjugate to the corneal apex Ep of the corneal Ec with respect to the collimator lens 22f.

[0035] The fixation target projection optical system 23 projects the fixation target onto the eye E under examination. This fixation target projection optical system 23 includes a fixation target light source 23a and a pinhole plate 23b (see Figure 3). Furthermore, the fixation target projection optical system 23 shares a dichroic mirror 22e and a collimator lens 22f with the XY alignment index projection optical system 22, and shares a half mirror 21e with the anterior segment observation optical system 21.

[0036] The fixation target light source 23a emits visible light as the 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 made into approximately parallel light by the collimator lens 22f and emitted towards the half mirror 21e, where it is reflected and travels along the optical axis O1 of the anterior segment 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 inside the nozzle 21b and reaches the eye E under examination. By having the subject fixate on this fixation target, the subject's line of sight can be fixed.

[0037] The applanation detection optical system 24 (see Figure 3) receives XY index reflected light and outputs a detection signal (also called an applanation signal or corneal deformation signal) indicating the amount of light from this 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 a half mirror 21g with the anterior segment observation optical system 21.

[0038] When the surface of the cornea Ec is considered to be flat, lens 24a focuses the XY index reflected light onto the aperture of the pinhole plate 24b. The aperture of the pinhole plate 24b is located at the focal point of lens 24a.

[0039] The light receiving sensor 24c is a photodiode that outputs a detection signal corresponding to the amount of light reflected from the XY index received, for example. This light receiving sensor 24c outputs the detection signal (also called a flattened waveform signal) to the control device 16.

[0040] The XY index reflected light passes through the inside of the nozzle 21b, through the chamber window glass 21d, and reaches the half mirror 21g. Then, a portion of the XY index reflected light is reflected by the half mirror 21g and enters the pinhole plate 24b via the lens 24a.

[0041] When the surface of the cornea Ec becomes flat (flattened) due to the blowing of air from the nozzle 21b, the flattening detection optical system 24 allows the entire XY index reflected light that has reached the flattening detection optical system 24 to reach the light receiving sensor 24c through the pinhole plate 24b. In addition, when the cornea Ec is not in a flattened state, the flattening 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 detection signal of the XY index reflected light output from the flattening detection optical system 24 gradually increases as the surface of the cornea Ec changes from a convex state to a flattened state, and then gradually decreases as it changes from a flattened state to a concave state.

[0042] The Z-alignment index projection optical system 25 (see Figure 2) projects Z-alignment index light for Z-axis alignment onto the cornea Ec from an oblique direction. This Z-alignment index projection optical system 25 comprises a Z-alignment light source 25a, a focusing lens 25b, an aperture diaphragm 25c, a pinhole plate 25d, and a collimator lens 25e, all along the optical axis O2.

[0043] The Z-alignment light source 25a emits infrared light (e.g., wavelength 860 nm). The aperture diaphragm 25c is positioned conjugate to the corneal apex Ep with respect to the collimator lens 25e. The collimator lens 25e is positioned to focus on the hole in the pinhole plate 25d.

[0044] Infrared light emitted from the Z-alignment light source 25a is focused by the focusing lens 25b, passes through the aperture diaphragm 25c, and proceeds to the pinhole plate 25d. After passing through the hole in the pinhole plate 25d, the infrared light is made into parallel light by the collimator lens 25e, and then enters the eye E as a Z-alignment indicator light, where it is reflected by the cornea Ec, forming a bright spot image in the eye E.

[0045] The Z-alignment detection optical system 26 receives the reflected light from the cornea Ec of the Z-alignment index light (hereinafter referred to as Z-index reflected light) and detects the positional relationship between the measurement head 14 and the cornea Ec in the Z-axis direction. This 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.

[0046] The cylindrical lens 26b is one that has power in the Y-axis 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 for example, a line sensor or a PSD (Position Sensitive Detector) is used.

[0047] The Z-index reflected light is focused by the imaging lens 26a and then proceeds to the cylindrical lens 26b, where it is focused in the Y-axis direction, forming a bright spot image on the light receiving sensor 26c.

[0048] In the XZ plane, the light-receiving sensor 26c is in a positional relationship with respect to the imaging lens 26a that is conjugate to the bright spot image formed on the eye E under examination by the Z-alignment index projection optical system 25. In the YZ plane, the light-receiving sensor 26c is in a positional relationship with respect to the imaging lens 26a and the cylindrical lens 26b that is conjugate to the corneal apex Ep. That is, since the light-receiving sensor 26c is conjugate to the aperture diaphragm 25c, even if the cornea Ec is shifted in the Y direction, the Z-index reflected light from the surface of the cornea Ec is efficiently incident on the light-receiving sensor 26c. The light-receiving sensor 26c then outputs a detection signal (hereinafter referred to as the Z detection signal) of the Z-index reflected light focused by the cylindrical lens 26b to the control device 16. This Z detection signal indicates the relative position of the eye E under examination in the Z direction with respect to the measurement head 14.

[0049] (Spraying mechanism) As shown in Figures 2 and 3, the measuring head 14 is equipped with a spraying mechanism 40.

[0050] Figure 4 is a schematic cross-sectional perspective view of the spraying mechanism 40, including the piston unit 1, viewed from above (in the Y direction). Figure 5 is a schematic perspective view of the piston unit 1 shown in Figure 4, viewed from above (in the Y direction).

[0051] As shown in Figures 4 and 5, the spraying mechanism 40 includes a chamber 41, a cylinder 42, a connecting pipe 43, a piston 44, a solenoid 45, a link joint 48, and a stopper 49. The cylinder 42, piston 44, solenoid 45, link joint 48, and stopper 49 of this spraying mechanism 40 correspond to the "piston unit" of this disclosure. A cover 17 that covers most of the piston unit 1 is attached to the measuring head 14 (see Figure 1).

[0052] A nozzle 21b is attached to the chamber 41 via a transparent glass plate 46. A chamber window glass 21d is also provided inside the chamber 41, opposite the nozzle 21b. Furthermore, a pressure sensor 47 is provided inside the chamber 41. This pressure sensor 47 outputs a pressure detection signal indicating the internal pressure inside the chamber 41 to the control device 16.

[0053] The cylinder 42 is attached to the upper surface 14a of the measuring head 14 by a mounting member 51 (see Figure 5) and is connected to the chamber 41 via a connecting pipe 43. This allows the inside of the cylinder 42 and the inside of the chamber 41 to communicate with each other via the connecting pipe 43.

[0054] Furthermore, a piston 44 is movably mounted inside the cylinder 42. The cylinder 42 and piston 44 together form an air compression chamber. In other words, as the piston 44 moves (forward) inside the cylinder 42, the air inside the cylinder 42 is compressed.

[0055] Furthermore, the cylinder 42 has a slit 42a that connects the inside and outside of the cylinder 42. This slit 42a is located forward in the Z direction from the initial position of the piston 44. In other words, when the piston 44 moving forward inside the cylinder 42 passes through the slit 42a, compression of the air inside the cylinder 42 begins. At the start of this compression, the pressure fluctuations inside the cylinder 42 are stabilized as the piston 44 passes through the slit 42a at high speed. Therefore, the Z-direction position of the slit 42a is set appropriately so that the piston 44 reaches a desired speed between its initial position and the slit 42a.

[0056] The solenoid 45 corresponds to the “drive unit” in this disclosure. The solenoid 45 is a known rotary solenoid and is screwed to the back side of the upper surface 14a of the measuring head 14. The solenoid 45 is also held down from above by a leaf spring 52 (see Figure 5) for noise reduction purposes.

[0057] Furthermore, the solenoid 45 has an arm 45a that rotates when the solenoid 45 is driven. This arm 45a is connected to the piston 44 via a link joint 48. Thus, when the solenoid 45 is driven under the control of the control device 16, the arm 45a rotates, and the rotational motion of the arm 45a is converted into linear motion of the piston 44 by the link joint 48. As a result, the piston 44 moves inside the cylinder 42, and the compressed air inside the cylinder 42 is blown from the nozzle 21b towards the cornea Ec of the eye E being examined, via the communication pipe 43 and the chamber 41.

[0058] Here, the location (reference numeral 45b) where the link joint 48 is connected in the arm portion 45a corresponds to the "first location" in this disclosure.

[0059] The link joint 48 corresponds to the “connecting part” in this disclosure. The link joint 48 has a link rod 481 and a pair of joints 482 attached to each end 481a located at both ends of the link rod 481. Each pair of joints 482 is attached to the end 481a with a small gap S (see Figure 11) between them. The link joint 48 connects the arm 45a and the piston 44 by fixing the pair of joints 482 to the piston 44 or to the first location 45b of the arm 45a, respectively.

[0060] The stopper 49 has a mounting portion 49a and is attached to the upper surface 14a of the measuring head 14 via the mounting portion 49a.

[0061] Furthermore, the stopper 49 has an operating-side receiving portion 49b that receives the arm portion 45a that rotates in the direction that advances the piston 44, and a returning-side receiving portion 49c that receives the arm portion 45a that rotates in the direction that retracts the piston 44.

[0062] Here, the portion of the arm portion 45a that is received by the operating-side receiving portion 49b (reference numeral 45c) corresponds to the "second location" in this disclosure. In this embodiment, the first location 45b is located closer to the rotation center of the arm portion 45a than the second location 45c.

[0063] The operating-side receiving portion 49b protrudes upward (in the Y direction) from the mounting portion 49a and is located on the rotational trajectory of the second location 45c. Multiple (two in this example) cushioning materials 50 are attached to the operating-side receiving portion 49b to reduce the impact noise when it receives the second location 45c of the rotating arm portion 45a.

[0064] The return-side receiving portion 49c protrudes upward (in the Y direction) from the mounting portion 49a and is located on the rotational trajectory of the second location 45c. A cushioning material 50 is attached to the return-side receiving portion 49c to reduce the impact noise when it receives the second location 45c of the rotating arm portion 45a.

[0065] Furthermore, the spraying mechanism 40 can obtain the air pressure when air is sprayed from the nozzle 21b onto the cornea Ec by detecting the internal pressure of the chamber 41 using the pressure sensor 47.

[0066] (Basic operation) Figure 6 is a schematic diagram of the piston unit 1 shown in Figure 4, viewed from above (in the Y direction), showing the configuration when the piston 44 is in its initial position. Figure 7 is a schematic diagram of the piston unit 1 shown in Figure 4, viewed from above (in the Y direction), showing the configuration when the piston 44 is in its final compression position.

[0067] Figure 8 is a schematic cross-sectional view of the piston unit 1 shown in Figure 4, viewed from the side (X direction), showing the configuration when the piston 44 is in its initial position. Figure 9 is a schematic cross-sectional view of the piston unit 1 shown in Figure 4, viewed from the side (X direction), showing the configuration when the piston 44 is in the compression start position. Figure 10 is a schematic cross-sectional view of the piston unit 1 shown in Figure 4, viewed from the side (X direction), showing the configuration when the piston 44 is in the compression end position.

[0068] The non-contact tonometer 10 of this disclosure has a wide measurement range of approximately 0 to 60 mmHg. In this embodiment, for example, measurement can be started in 30 mmHg mode and, if necessary, in 60 mmHg mode. In this embodiment, for example, the control device 16 achieves measurement according to each mode by changing the voltage value applied to the solenoid 45. In this case, the basic operation described later is common to each mode.

[0069] With the piston 44 in its initial position (see Figures 6 and 8), when the solenoid 45 is driven under the control of the control device 16, the arm 45a rotates. Then, the rotational motion of the arm 45a is converted into linear motion of the piston 44 by the link joint 48, causing the piston 44 to move forward within the cylinder 42.

[0070] As the piston 44 moves forward within the cylinder 42, it reaches a desired speed before reaching the slit 42a formed in the cylinder 42. Once the piston 44 passes through the slit 42a (see Figure 9), compression of the air within the cylinder 42 begins.

[0071] As the piston 44 moves forward, the air inside the cylinder 42 is compressed, and this air is blown from the nozzle 21b towards the cornea Ec of the eye E under examination via the connecting pipe 43 and the chamber 41. Before and after the air begins to be blown from the nozzle 21b onto the cornea Ec, the second point 45c of the arm 45a is received by the operating side receiving part 49b via the cushioning material 50 (see Figure 7), and the piston 44 is positioned at the end of the compression (see Figure 10). In other words, the operating side receiving part 49b prevents the arm 45a from rotating more than necessary due to inertia after the solenoid 45 stops moving. This prevents the piston 44 from moving further forward from the end of the compression, thus preventing unnecessary air from being blown onto the cornea Ec.

[0072] Furthermore, while air is being blown onto the cornea Ec from the nozzle 21b, the control device 16 controls the XY alignment index projection optical system 22 and the applanation detection optical system 24 to turn on the XY alignment light source 22a and to receive the XY index reflected light with the light receiving sensor 24c (see Figure 3). As a result, while air is being blown onto the cornea Ec from the nozzle 21b, the XY alignment index light is continuously projected onto the cornea Ec from the XY alignment index projection optical system 22. At the same time, the light receiving sensor 24c continuously receives the XY index reflected light and continuously outputs a detection signal of this XY index reflected light to the control device 16.

[0073] The control device 16 then analyzes the peak position of the flattened waveform based on the detection signal of the XY index reflected light input from the light receiving sensor 24c using a known method, and calculates the intraocular pressure value of the eye under examination E using a known method based on the peak position of the flattened waveform, the signal intensity of the flattened waveform corresponding to this peak position, and the detection result of the pressure sensor 47. Subsequently, the control device 16 stores the calculated intraocular pressure value of the eye under examination E in a storage unit (not shown) as the measurement result of the intraocular pressure value and displays it on the monitor 15.

[0074] (Reduced operating noise) As mentioned above, in the invention disclosed in Patent Document 1, although a cushioning material is provided in the air-extrusion part of the air-extrusion part and the piston-drive part, which are spaced apart from each other, a loud impact noise is generated when the air-extrusion part and the piston-drive part are joined together. This is because, since the piston-drive part is moving in a linear motion, the kinetic energy of the piston-drive part is quickly converted into energy that causes the impact noise.

[0075] On the other hand, in the non-contact tonometer 10 of this disclosure, an impact sound may be generated when the second location 45c of the arm portion 45a is received by the operating side receiving portion 49b via the cushioning material 50. However, because the non-contact tonometer 10 of this disclosure receives the rotating arm portion 45a, the rate at which the kinetic energy (rotational energy) of the arm portion 45a is converted into energy that causes an impact sound is slower compared to the invention disclosed in Patent Document 1 mentioned above. In other words, the non-contact tonometer 10 of this disclosure can reduce operating noise (especially impact noise) while ensuring performance.

[0076] Figure 11 is a schematic enlarged cross-sectional view showing the gap S between the end 481a of the link rod 481 and the joint 482 in the link joint 48 shown in Figure 4.

[0077] The inventors, after diligently studying to solve the aforementioned problems, also focused on the collision sound between each end 481a of the link rod 481 and the joint 482 during the operation of the non-contact tonometer 10. Therefore, they collected collision sounds from two types of link joints, each with a gap S (see Figure 11) between each end 481a and the joint 482 set to 0.2 mm or 0.7 mm. The results showed that the sound pressure level was 79.6 dBA when the gap S was 0.7 mm, compared to 74.4 dBA when the gap S was 0.2 mm. This confirmed that the collision sound decreases as the gap S decreases. On the other hand, if the gap S is set to 0 mm, the link joint 48 may not be able to smoothly convert the rotational motion of the arm portion 45a into the linear motion of the piston 44. Therefore, it is preferable that the gap S of the link joint 48 be greater than 0 mm and as small as possible.

[0078] [Second Embodiment] Figure 12 is a schematic perspective view of the piston unit 1A of the non-contact tonometer 10A according to the second embodiment of this disclosure, viewed from above (Y direction).

[0079] In the non-contact tonometer 10 according to the first embodiment described above, the first location 45b is located closer to the rotation center of the arm portion 45a than the second location 45c. However, as shown in Figure 12, in the non-contact tonometer 10A according to the second embodiment, the second location 45c is located closer to the rotation center than the first location 45b. Except for the positional relationship between the first location 45b and the second location 45c on the arm portion 45a, the configuration of the first embodiment and the second embodiment are basically the same, and similar effects can be obtained.

[0080] In the non-contact tonometer 10A according to the second embodiment, the second location 45c is located closer to the rotation center than the first location 45b, so the leaf spring 52 is positioned on the inside of the upper surface 14a of the measuring head 14, compared to the non-contact tonometer 10 according to the first embodiment.

[0081] (Comparison with the first embodiment) Figure 13 is a diagram for comparing the magnitude of rotational energy in the non-contact tonometer 10 according to the first embodiment and the non-contact tonometer 10A according to the second embodiment. Below, the magnitude of rotational energy in the non-contact tonometer 10 according to the first embodiment and the non-contact tonometer 10A according to the second embodiment will be compared with reference to Figure 13. As a prerequisite, the velocity V when the piston 44 passes through the slit 42a and the mass m of the arm portion 45a are the same between the non-contact tonometer 10 according to the first embodiment and the non-contact tonometer 10A according to the second embodiment. In other words, velocity V and mass m are constants.

[0082] In the non-contact tonometer 10 according to the first embodiment, if the distance from the rotation center of the arm 45a to the first point 45b is r1, and the distance from the rotation center of the arm 45a to the second point 45c is L1, then the angular velocity ω1 of the rotating arm 45a, the moment of inertia I1 of the second point 45c, and the rotational energy E1 of the second point 45c are given by the following equations, respectively.

[0083] ω1 = V / r1 I1 = m·L1 2 E1=(I1·ω1 2 / 2)=(m·L1 2 (V / r1) 2 ) / 2···(1)

[0084] In the non-contact tonometer 10A according to the second embodiment, if the distance from the rotation center of the arm 45a to the first point 45b is r2, and the distance from the rotation center of the arm 45a to the second point 45c is L2, then the angular velocity ω2 of the rotating arm 45a, the moment of inertia I2 of the second point 45c, and the rotational energy E2 of the second point 45c are given by the following equations, respectively.

[0085] ω² = V / r² I2 = m·L2 2 E2=(I2·ω2 2 / 2)=(m·L2 2 (V / r2) 2 ) / 2···(2)

[0086] And r1<r2、L1> Since L2, it can be confirmed from equations (1) and (2) above that E1 > E2. In other words, the non-contact tonometer 10A according to the second embodiment has less rotational energy than the non-contact tonometer 10 according to the first embodiment. Therefore, the impact sound when the second location 45c is received by the operating side receiving part 49b via the cushioning material 50 is smaller for the non-contact tonometer 10A according to the second embodiment than for the non-contact tonometer 10 according to the first embodiment.

[0087] As described above, the non-contact tonometer 10A according to the second embodiment has the advantage of being able to reduce operating noise (especially impact noise) more effectively than the first embodiment.

[0088] In the non-contact tonometer 10A according to the second embodiment, the angular velocity of the rotating arm 45a is smaller (ω1 > ω2) compared to the non-contact tonometer 10 according to the first embodiment, so it takes longer for the piston 44 to reach speed V. For this reason, in the non-contact tonometer 10A according to the second embodiment, the distance from the initial position of the piston 44 to the slit 42a is set to be longer compared to the non-contact tonometer 10 according to the first embodiment.

[0089] Incidentally, as mentioned above, by setting a long distance from the initial position of the piston 44 to the slit 42a, there is a possibility that the piston 44 may pop out of the cylinder 42. For this reason, in the non-contact tonometer 10A according to the second embodiment, the overall length of the piston 44 is set to be shorter than that of the non-contact tonometer 10 according to the first embodiment (x1>x2, see Figure 13).

[0090] In the non-contact tonometer 10 according to the first embodiment, two cushioning materials 50 are attached to the operating side receiving portion 49b. However, the non-contact tonometer 10A according to the second embodiment has less rotational energy (E1>E2) than the non-contact tonometer 10 according to the first embodiment. For this reason, in the non-contact tonometer 10A according to the second embodiment, for example, only one cushioning material 50 may be attached to the operating side receiving portion 49b.

[0091] [others] While embodiments have been described above with reference to the attached drawings, this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents can be conceived within the scope of the claims, and these are also understood to fall within the technical scope of this disclosure. Furthermore, the components of the embodiments described above can be combined in any way without departing from the spirit of the invention.

[0092] For example, in each of the above embodiments, air is blown towards the cornea Ec of the eye E under examination, but various fluids other than air may be blown instead.

[0093] Furthermore, the configuration of the non-contact tonometers 10 and 10A, other than the piston units 1 and 1A, is not particularly limited to those shown in Figures 1 to 3, and any configuration used in known non-contact tonometers or their combined devices may be used as appropriate.

[0094] [Note] Based on the above, at least the following information is disclosed:

[0095] (1) A piston unit included in a non-contact tonometer used for measuring the intraocular pressure of an eye under examination, A nozzle that sprays fluid onto the cornea of ​​the eye under examination is provided with a cylinder that delivers the fluid via an internal piston, A drive unit having a rotating arm, A connecting portion that connects the first part of the arm to the piston, A stopper that receives the second part of the rotating arm, A piston unit equipped with a piston unit.

[0096] This configuration reduces the impact noise generated compared to a case where a piston moving in a straight line is stopped by a stopper.

[0097] (2) The second location is located closer to the center of rotation of the arm than the first location. The piston unit described in (1) above.

[0098] This configuration allows for a reduction in rotational energy compared to the case where the first point is located closer to the center of rotation of the arm than the second point, thus more effectively reducing impact noise.

[0099] (3) The connecting portion comprises a link rod and a joint attached to the end of the link rod. A gap is formed between the end of the link rod and the joint. The piston unit described in (1) or (2) above.

[0100] This configuration allows for the smooth conversion of the arm's rotational motion into the piston's linear motion, while also reducing the noise of collisions between the end of the link rod and the joint.

[0101] (4) A non-contact tonometer used for measuring the intraocular pressure of the eye under examination, The device has a piston unit as described in any one of (1) to (3) above, and is equipped with a spraying mechanism that sprays fluid from a nozzle onto the cornea of ​​the eye to be examined. Non-contact tonometer.

[0102] This configuration allows for reduced operating noise while maintaining performance. [Explanation of symbols]

[0103] 1.1A Piston Unit 10,10A Non-contact tonometer 11 Bass 12 Face support section 12a Jaw support 12b Forehead area 12c post 13 Moving mechanism 14 Measuring head 14a Top side 15 monitors 16 Control device 17 Cover 21b Nozzle 40 Spraying mechanism 41 Chambers 42 cylinders 42a Slit 43 Communication pipe 44 pistons 45 Solenoid 45a Arm 45b First location 45c Second location 48 Link Joint 481 Link Rod 482 joints 49 Stopper 49b Operating side receiving part 50 Cushioning material

Claims

1. A piston unit included in a non-contact tonometer used for measuring the intraocular pressure of an eye under examination, A nozzle that sprays fluid onto the cornea of ​​the eye under examination is provided with a cylinder that delivers the fluid via an internal piston, A drive unit having a rotating arm, A connecting portion that connects the first part of the arm to the piston, A stopper that receives the second part of the rotating arm, A piston unit equipped with a piston unit.

2. The second location is located closer to the center of rotation of the arm than the first location. The piston unit according to claim 1.

3. The connecting portion comprises a link rod and a joint attached to the end of the link rod. A gap is formed between the end of the link rod and the joint. The piston unit according to claim 1.

4. A non-contact tonometer used for measuring the intraocular pressure of the eye under examination, The device has a piston unit according to any one of claims 1 to 3, and is equipped with a spraying mechanism that sprays fluid from a nozzle onto the cornea of ​​the eye under examination. Non-contact tonometer.

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