Pharmaceutical liquid administration device and rotation detection device

Abstract

A rotary body (second gear (62)) of a pharmaceutical liquid administration device (10) has an irradiated part (80) that is an outer surface along the axis (Ax) of the rotary body. A rotation sensor (70) has a light-emitting element (72) that emits irradiation light toward the irradiated part (80) and a light-receiving element (74) that receives light reflected from the irradiated part (80) of the rotary body. The irradiated part (80) has at least two regions that are different in the intensity of the reflected light in the circumferential direction of the rotary body. The intensity of the reflected light changes as the irradiated part (80) completes one rotation around the axis. A control unit (58) detects the rotation state of the rotary body on the basis of changes in the current value corresponding to the intensity of the reflected light.

Description

Drug solution administration device and rotation detection device

[0001] The present invention relates to a drug solution administration device and a rotation detection device.

[0002] It is conventionally known to use an encoder to detect the rotation of a rotating body in a drug solution administration device, as disclosed in, for example, JP-A-2013-537844.

[0003] In the medical liquid administration device disclosed in JP 2013-537844, an encoder attached to the motor shaft is used to detect the rotation of the motor. In this structure, the encoder protrudes significantly in a direction perpendicular to the axis of the motor shaft, making it difficult to reduce the size of the medical liquid administration device.

[0004] The present invention aims to solve the above-mentioned problems.

[0005] (1) A first aspect of the present invention is a drug solution administration device comprising: a drug solution container that contains a drug solution and has a drug solution discharge port at its tip; a pusher that pushes the drug solution in the drug solution container out of the drug solution discharge port; a motor; a rotating body that transmits the rotation of the motor to the pusher, a drive mechanism that moves the pusher toward the tip; a rotation sensor for detecting the rotation of the rotating body; and a control unit, wherein the rotating body has an irradiated portion that is an outer surface along the axis of the rotating body, and the rotation sensor has a light-emitting element that emits irradiated light toward the irradiated portion and a light-receiving element that receives reflected light from the irradiated portion of the rotating body, the irradiated portion has at least two regions in the circumferential direction of the rotating body where the intensity of the reflected light differs, and when the irradiated portion rotates once around the axis, the intensity of the reflected light changes, and the control unit detects the rotation state of the rotating body based on a change in current value corresponding to the intensity of the reflected light.

[0006] This drug solution administration device emits light toward the irradiated part, which is the outer surface along the axis of the rotating body, receives reflected light from the irradiated part, and detects the rotational state of the rotating body based on changes in the current value corresponding to the intensity of the reflected light, making it easy to miniaturize the drug solution administration device.

[0007] (2) In the drug solution administration device described in (1) above, the outer peripheral surface of the irradiated portion may have a first irradiated surface and a second irradiated surface in which the intensity of the reflected light is lower than that of the first irradiated surface.

[0008] This configuration makes it easy to provide at least two regions with different intensities of reflected light.

[0009] (3) In the drug solution administration device described in (2) above, the irradiated portion may have a metal portion and a resin portion in which the intensity of the reflected light is lower than that of the metal portion, and the first irradiated surface may be provided on the metal portion and the second irradiated surface may be provided on the resin portion.

[0010] This configuration makes it possible to easily provide two regions with different intensities of reflected light on the irradiated portion.

[0011] (4) In the drug solution administration device described in (2) above, the cross-sectional shape of the irradiated portion perpendicular to the axis may be circular, half the circumference of the outer surface of the irradiated portion may be the first irradiated surface, and the remaining half the circumference of the irradiated portion may be the second irradiated surface.

[0012] With this configuration, the areas of high and low intensity of reflected light when the irradiated part rotates once are equal in size, thereby improving the resolution of rotation detection.

[0013] (5) In the drug solution administration device described in (1) above, the cross-sectional shape of the irradiated portion perpendicular to the axis may be circular, and the irradiated portion may be provided with a through hole that penetrates the circle in a radial direction.

[0014] This configuration makes it easy to provide at least two regions with different intensities of reflected light.

[0015] (6) In the drug solution administration device described in (1) above, the cross section of the irradiated portion perpendicular to the axis may have a polygonal shape.

[0016] With this configuration, the rotation state of the rotor can also be detected based on the change in the current value corresponding to the intensity of the reflected light.

[0017] (7) In the drug solution administration device described in any one of (1) to (6) above, the maximum value of the current when the irradiated portion rotates once around the axis may be 10 times or more the minimum value.

[0018] This configuration improves the accuracy of rotation detection.

[0019] (8) In the drug solution administration device described in any one of (1) to (7) above, the control unit may measure the number of rotations of the rotating body based on the change in the current value corresponding to the intensity of the reflected light.

[0020] By measuring the number of rotations, it is possible to know whether or not the delivery of the chemical solution has been completed.

[0021] A second aspect of the present invention is a rotation detection device comprising a rotating body and a rotation sensor that detects the rotation of the rotating body, wherein the rotating body has an irradiated portion which is an outer surface along the axis of the rotating body, the rotation sensor has a light-emitting element that emits irradiation light toward the irradiated portion and a light-receiving element that receives reflected light from the irradiated portion of the rotating body, the irradiated portion has at least two regions in the circumferential direction of the rotating body where the intensity of the reflected light differs, and the intensity of the reflected light changes when the irradiated portion rotates once around the axis.

[0022] According to the present invention, light is emitted toward the irradiated part, which is the outer surface along the axis of the rotating body, reflected light from the irradiated part is received, and the rotational state of the rotating body is detected based on changes in the current value corresponding to the intensity of the reflected light, making it easy to miniaturize the drug solution administration device and rotation detection device.

[0023] FIG. 1 is a perspective view of a drug solution administration device according to an embodiment of the present invention. FIG. 2 is a perspective view of a syringe pump unit. FIG. 3 is a plan view of the syringe pump unit. FIG. 4 is a perspective view of a second gear, which is a rotating body. FIG. 5A is a schematic view of an irradiated portion when the rotation angle is 0°. FIG. 5B is a schematic view of an irradiated portion when the rotation angle is 90°. FIG. 5C is a schematic view of an irradiated portion when the rotation angle is 180°. FIG. 5D is a schematic view of an irradiated portion when the rotation angle is 270°. FIG. 6 is a graph showing the relationship between the rotation angle of a rotating body and the intensity of reflected light. FIG. 7 is a perspective view of a rotating body having an irradiated portion according to a first modified example. FIG. 8A is a schematic view of an irradiated portion according to the first modified example when the rotation angle is 0°. FIG. 8B is a schematic view of an irradiated portion according to the first modified example when the rotation angle is 90°. FIG. 8C is a schematic view of an irradiated portion according to the first modified example when the rotation angle is 180°. FIG. 8D is a schematic diagram of an irradiated portion according to the first modified example when the rotation angle is 270°. FIG. 9 is a graph showing the relationship between the rotation angle of a rotating body having an irradiated portion according to the first modified example and the intensity of reflected light. FIG. 10A is a schematic diagram of an irradiated portion according to the second modified example when the rotation angle is 0°. FIG. 10B is a schematic diagram of an irradiated portion according to the second modified example when the rotation angle is 90°. FIG. 10C is a schematic diagram of an irradiated portion according to the second modified example when the rotation angle is 180°. FIG. 10D is a schematic diagram of an irradiated portion according to the second modified example when the rotation angle is 270°. FIG. 11 is a graph showing the relationship between the rotation angle of a rotating body having an irradiated portion according to the second modified example and the intensity of reflected light.

[0024] The medicinal solution administration device 10 shown in Fig. 1 is attached to the skin of a living patient and is used to administer a medicinal solution subcutaneously to the patient. The medicinal solution administration device 10 continuously administers a medicinal solution into the living body over a relatively long period of time (e.g., several minutes to several hours). The medicinal solution administration device 10 may also administer a medicinal solution into the living body intermittently. Examples of medicinal solutions include protein preparations such as insulin preparations, narcotic analgesics, and diuretics.

[0025] The drug solution administration device 10 includes a housing 12 , a puncture section 14 , a syringe pump section 16 , an adhesive member 18 , and a release sheet 20 .

[0026] Housing 12 extends in one direction (X direction). Housing 12 has a bottom wall 22 that forms a wall on one side in the thickness direction (Z direction) of housing 12, and a ceiling 24 that forms a wall on the other side in the thickness direction of housing 12. An operation cover 26 is provided on ceiling 24 at one longitudinal end (end in the X1 direction) of housing 12. When operation cover 26 is operated (pressed), puncturing unit 14 is activated.

[0027] An insertion port 13 for inserting a syringe pump unit 16 into the housing 12 is provided at the other end in the longitudinal direction (the end in the X2 direction) of the housing 12 .

[0028] The puncturing unit 14 is attached to the housing 12. The puncturing unit 14 includes a needle member 142 that includes a puncturing needle 141. The needle member 142 is movable in the puncturing direction (Z1 direction) relative to the housing 12. When the operation cover 26 is operated (pressed), the puncturing needle 141 protrudes from the housing 12 in the Z1 direction due to the biasing force of a puncturing biasing member (not shown), and punctures the skin.

[0029] As shown in Fig. 2, the syringe pump unit 16 has a chassis member 30, a pre-filled syringe 32, a plunger 34, and a drive mechanism 36. Fig. 2 shows a state in which the top cover 38 (see Fig. 1) of the syringe pump unit 16 is removed. The syringe pump unit 16 is disposed inside the housing 12 in a state in which it can slide along the longitudinal direction (X direction) of the housing 12.

[0030] 3, the pre-filled syringe 32 includes a liquid medicine container 40, a gasket 42, a sealing member 44, and a tip cap 46. The liquid medicine container 40 is supported by the chassis member 30. The liquid medicine container 40 has a liquid medicine outlet 41 at its tip. The liquid medicine container 40 is pre-filled with the liquid medicine.

[0031] Gasket 42 is made of an elastic resin material such as rubber or elastomer, and is slidably disposed inside liquid medicine container 40. Sealing member 44 is made of an elastic resin material such as rubber or elastomer, and liquid-tightly seals liquid medicine discharge port 41 of liquid medicine container 40. Tip cap 46 fixes sealing member 44 to liquid medicine discharge port 41 of liquid medicine container 40.

[0032] The plunger 34 presses the gasket 42 in the distal direction within the liquid medicine container 40, forcing the liquid medicine within the liquid medicine container 40 out of the liquid medicine discharge port 41. Although not shown in detail, the plunger 34 has an extendable structure. Therefore, the plunger 34 has multiple cylindrical members overlapping in the radial direction. The multiple cylindrical members are displaceable relative to one another in the axial direction (X direction) of the liquid medicine container 40. The plunger 34 can be extended by the multiple cylindrical members being displaced relative to one another in the axial direction. The plunger 34 extends while moving in the distal direction, thereby pressing the gasket 42 in the distal direction and moving the gasket 42 forward.

[0033] The drive mechanism 36 has a motor 50 and a power transmission unit 52. The motor 50 is supported by the chassis member 30. The power transmission unit 52 has a plurality of rotating bodies. The plurality of rotating bodies include a first gear 61 connected to the output shaft of the motor 50, a second gear 62 that meshes with the first gear 61, a third gear 63 that meshes with the second gear 62, and a fourth gear 64 that meshes with the third gear 63. The axes (rotation axes) of the first to fourth gears 61 to 64 are parallel to one another.

[0034] The first gear 61 is a pinion gear and is disposed coaxially with the output shaft of the motor 50. The second gear 62 is an intermediate gear and is rotationally driven by the first gear 61. The second gear 62 has a large gear 621 that meshes with the first gear 61 and a small gear 622 that meshes with the third gear 63. The third gear 63 is an idle gear and is rotationally driven by the second gear 62.

[0035] The fourth gear 64 is an output gear, and is rotationally driven by the third gear 63. A feed screw 66 is fixed to the center of the fourth gear 64. The feed screw 66 is threadedly engaged with the plunger 34. As the feed screw 66 rotates, the plunger 34 moves toward the tip while extending.

[0036] The power transmission unit 52 is not limited to a gear mechanism as in this embodiment, but may be configured, for example, by a belt mechanism having a belt and a plurality of pulleys.

[0037] Syringe pump unit 16 further includes a battery 54, a circuit board 56, and a control unit 58. Battery 54 is held in a battery housing portion of chassis member 30 and supplies power to motor 50. Circuit board 56 is supported by chassis member 30 at a position adjacent to chemical solution container 40. Control unit 58 is mounted on circuit board 56 and is configured by a processor such as a CPU (Central Processing Unit). Control unit 58 controls the rotation of motor 50.

[0038] As shown in FIG. 2 , the syringe pump unit 16 further includes a rotation sensor 70 that detects the rotation of one of the multiple rotating bodies. The rotation sensor 70 is disposed on the rear surface (the surface facing the Z1 direction) of the circuit board 56, and faces an irradiated portion 80, which will be described later. In this embodiment, the rotation sensor 70 detects the rotation of the second gear 62. As shown in FIG. 4 , the rotation sensor 70 includes a light-emitting element 72 that emits irradiated light toward the irradiated portion 80, and a light-receiving element 74 that receives light reflected from the irradiated portion 80. The rotation sensor 70 is a reflective photoelectric sensor with a light-receiving and light-emitting function.

[0039] The irradiated light emitted by the light-emitting element 72 is, for example, infrared light. The irradiated light may be visible light. The light-emitting element 72 may emit the irradiated light continuously or may emit the irradiated light intermittently at short intervals. When the irradiated light is emitted intermittently, the power consumption of the battery 54 can be reduced.

[0040] The rotation sensor 70 is not limited to being configured as a single unit such as a reflective photoelectric sensor with light receiving and emitting functions, but may be configured such that the light emitting element 72 and the light receiving element 74 are individually mounted on the circuit board 56.

[0041] The second gear 62, which is a rotating body, has an irradiated portion 80, which is an outer surface along the axis Ax (axial line) of the second gear 62. The irradiated portion 80 is arranged on the axis Ax of the second gear 62. The irradiated portion 80 is the shaft portion of the second gear 62. A rotation detection device is configured by the rotating body having the irradiated portion 80 and the rotation sensor 70 described above. The irradiated portion 80 protrudes from the large gear 621 in the axial direction of the second gear 62. The cross section of the irradiated portion 80 perpendicular to the axis Ax is circular. In other words, the irradiated portion 80 is formed in a cylindrical shape. The irradiated portion 80 has a smaller diameter than the large gear 621 and the small gear 622.

[0042] The irradiated portion 80 has at least two regions in the circumferential direction of the second gear 62 that have different intensities of reflected light. In this embodiment, the irradiated portion 80 is provided with through-holes 82 that penetrate the circle in the radial direction, thereby forming the at least two regions in which the intensities of reflected light differ. In order to facilitate light reflection on the outer peripheral surface 81 of the irradiated portion 80, the irradiated portion 80 is preferably made of a light-colored material (e.g., whitish). Alternatively, the irradiated portion 80 may be made of metal. As long as the outer peripheral surface 81 of the irradiated portion 80 has a structure that easily reflects light (e.g., a reflective coating or a reflective sheet), the inner side of the outer peripheral surface 81 may be made of a material that does not easily reflect light (e.g., black resin).

[0043] As shown in FIG. 5A , when the irradiated light passes through the through-hole 82, the irradiated light is irradiated onto the inner wall of the housing 12 (hereinafter referred to as the "light-receiving wall 121"). The light-receiving wall 121 is positioned opposite the rotation sensor 70 and is a wall that easily absorbs the irradiated light. In other words, the light-receiving wall 121 is a wall that does not easily reflect the irradiated light. The light-receiving wall 121 is, for example, a black wall. The light-receiving wall 121 may also be a black sheet fixed to the inner wall of the housing 12. When the irradiated light passes through the through-hole 82, almost no reflected light is generated, or even if it is generated, it is very small. Therefore, the intensity of the reflected light received by the light-receiving element 74 of the rotation sensor 70 is low (relatively low).

[0044] As shown in Figure 5B, when the irradiated light is irradiated onto the outer peripheral surface 81 of the irradiated portion 80 without passing through the through-hole 82, the irradiated light is reflected by the outer peripheral surface 81 of the irradiated portion 80, and the light-receiving element 74 of the rotation sensor 70 receives the reflected light. Therefore, the intensity of the reflected light received by the light-receiving element 74 of the rotation sensor 70 is high (relatively high). Hereinafter, a relatively low intensity of reflected light will also be referred to as "dark." A relatively high intensity of reflected light will also be referred to as "bright." The level of intensity of reflected light will also be referred to as "brightness."

[0045] The control unit 58 detects the rotation state of the second gear 62, which is a rotating body, based on the change in the current value corresponding to the intensity of the reflected light. Specifically, the control unit 58 measures the number of rotations of the second gear 62 based on the change in the current value corresponding to the intensity of the reflected light. The operation of the control unit 58 will be described in detail below.

[0046] 1 , the adhesive member 18 is a flexible sheet-like member. The adhesive member 18 is fixed to the bottom wall portion 22 of the housing 12. An adhesive surface (adhesive surface) that can be attached to the skin of a living body is provided on the surface of the adhesive member 18 opposite the housing 12. A release sheet 20 is removably attached to the adhesive surface of the adhesive member 18 in the initial state of the medical solution administration device 10.

[0047] The drug solution administration device 10 is used as follows.

[0048] When using the drug solution administration device 10, the user inserts the syringe pump unit 16 into the housing 12. This causes a connecting needle (not shown) provided inside the housing 12 to penetrate the sealing member 44 (see FIG. 3 ) of the prefilled syringe 32, allowing the drug solution in the prefilled syringe 32 to be delivered to the puncture needle 141. Next, the user peels the release sheet 20 from the adhesive member 18 to expose the adhesive surface of the adhesive member 18. After peeling the release sheet 20, the user attaches the adhesive member 18 to the skin of a living body.

[0049] Next, when the user presses the operation cover 26 in the Z1 direction, the needle member 142 including the puncture needle 141 is displaced in the Z1 direction (puncture direction) by the elastic biasing force of the puncture biasing member (not shown). As a result, the puncture needle 141 punctures the skin of the living body. After the puncture needle 141 has completely punctured the skin, the user turns on the power of the medicinal solution administration device 10, and the motor 50 shown in FIG. 3 is activated. The motor 50 advances the plunger 34 and the gasket 42 via the power transmission unit 52. This causes the medicinal solution to be administered to the living body.

[0050] In the medicinal solution administration device 10, the state of medicinal solution delivery can be determined based on the detection result of the rotation sensor 70. Specifically, the control unit 58 can determine the state of medicinal solution delivery by the plunger 34 by measuring the number of rotations or rotation speed of the second gear 62 based on the detection result of the rotation sensor 70. The following items (1) to (4), for example, can be determined by measuring the number of rotations or rotation speed of the second gear 62.

[0051] (1) When the second gear 62 rotates at a predetermined time interval, the control unit 58 determines that the liquid is being delivered normally.

[0052] (2) When the second gear 62 reaches a predetermined number of rotations, the control unit 58 determines that the liquid transfer is complete.

[0053] (3) If the rotation speed of the second gear 62 becomes slower than the normal speed while there is liquid medicine remaining in the liquid medicine container 40, the control unit 58 determines that the liquid medicine flow path from the liquid medicine outlet 41 of the liquid medicine container 40 to the tip of the puncture needle 141 is about to become blocked.

[0054] (4) If the rotation of the second gear 62 stops while the liquid medicine remains in the liquid medicine container 40, the control unit 58 determines that the liquid medicine flow path is blocked.

[0055] As described above, the irradiated portion 80 has at least two regions in which the intensity of reflected light differs in the circumferential direction of the second gear 62. Therefore, the intensity of the reflected light changes when the irradiated portion 80 makes one rotation about the axis line Ax. The control unit 58 detects the rotation state of the second gear 62 based on the change in the current value corresponding to the intensity of the reflected light.

[0056] 5A to 5D, the irradiated portion 80 is provided with a through-hole 82, and therefore the intensity of the reflected light received by the light-receiving element 74 (brightness or darkness of the reflected light) alternates with the rotation of the second gear 62. Specifically, as shown in FIGS. 5A and 5C, when the rotation angle of the second gear 62 is 0° and 180°, the irradiated light passes through the through-hole 82, and therefore the intensity of the reflected light is low (dark). As shown in FIGS. 5B and 5D, when the rotation angle of the second gear 62 is 90° and 270°, the irradiated light is reflected by the outer peripheral surface 81 of the irradiated portion 80, and therefore the intensity of the reflected light is high (bright).

[0057] As a result, the intensity of the reflected light changes as shown in Figure 6. The light-receiving element 74 generates an electric signal (current) whose magnitude corresponds to the intensity of the reflected light, so the current value also changes as the second gear 62 rotates. A change in the current value from a low state to a high state, or a change in the current value from a high state to a low state, indicates that the second gear 62 is rotating.

[0058] As shown in Figure 6, in this embodiment, when the second gear 62 makes one rotation, the current value changes from a low state to a high state twice and from a high state to a low state twice (a total of four changes). Therefore, the control unit 58 can detect the rotation state of the second gear 62 based on the change in the current value corresponding to the intensity of the reflected light. The rotation state of the second gear 62 detected by the control unit 58 includes the number of rotations and the rotation speed of the second gear 62. The control unit 58 may detect only one of the number of rotations and the rotation speed of the second gear 62.

[0059] The manner of determining the "change in current value" described above is not particularly limited. For example, a predetermined threshold value Th is set in the middle between the high current value and the low current value. In this case, the control unit 58 determines a change from a current value range exceeding the threshold value Th to a current value range equal to or less than the threshold value Th, and a change from a current value range equal to or less than the threshold value Th to a current value range exceeding the threshold value Th, as a "change in current value," and detects the rotation of the second gear 62.

[0060] Alternatively, two thresholds (a first threshold Th1 and a second threshold Th2) may be set for the current value. In this case, the control unit 58 determines that a current value exceeding the first threshold Th1 is a high current value, and that a current value below the second threshold Th2 is a low current value, and determines a change from a high current value to a low current value and a change from a low current value to a high current value as a "change in current value," thereby detecting the rotation of the second gear 62.

[0061] This embodiment has the following advantages.

[0062] 5A to 5D, the rotation sensor 70 emits light toward the irradiated portion 80, which is the outer surface of the rotating body (second gear 62) along the axis Ax, and receives light reflected from the irradiated portion 80. The control unit 58 (see FIG. 3) detects the rotation state of the rotating body based on changes in the current value corresponding to the intensity of the reflected light. This makes it easier to miniaturize the medicinal solution administration device 10 shown in FIG. 1 compared to a configuration in which rotation is detected using an encoder that extends significantly radially from the motor shaft.

[0063] 4, the cross section of the irradiated portion 80 perpendicular to the axis Ax has a circular shape, and a through-hole 82 that penetrates the circular shape in the radial direction is provided in the irradiated portion 80. This configuration makes it easy to provide at least two regions with different intensities of reflected light.

[0064] The control unit 58 measures the number of rotations of the rotor (second gear 62) based on the change in the current value corresponding to the intensity of the reflected light. By measuring the number of rotations, it is possible to determine whether or not the delivery of the medicinal solution has been completed.

[0065] It should be noted that the rotating body on which the irradiated portion 80 is provided is not limited to the second gear 62. As a first alternative embodiment, the irradiated portion 80 may be provided on the first gear 61, the third gear 63, or the fourth gear 64 shown in Fig. 3. When the power transmission unit 52 is configured with a belt mechanism instead of a gear mechanism, as a second alternative embodiment, the irradiated portion 80 may be provided on any one of the pulleys. The first alternative embodiment and the second alternative embodiment also apply to the first and second modified examples described below.

[0066] Instead of the irradiated portion 80 having the through-hole 82 shown in FIG. 4 and the like, a first modified example or a second modified example described below may be employed.

[0067] 7 includes a metal part 84 and a resin part 86 that reflects light with a lower intensity than the metal part 84. The cross section of the irradiated part 80A, which includes the metal part 84 and the resin part 86 and is perpendicular to the axis Ax, has a circular shape. That is, the irradiated part 80A is substantially cylindrical.

[0068] The resin portion 86 is made of, for example, a resin material that is colored black in order to reduce the intensity of light reflected from the resin portion 86. A pair of grooves 83 that are aligned along the axial direction of the second gear 62 are formed in the resin portion 86 at locations that are opposite each other in the circumferential direction.

[0069] 8A , the portion of the outer circumferential surface of resin part 86 that is not covered by metal part 84 (hereinafter referred to as "exposed outer circumferential surface 861") is an arcuate surface. The portion of the outer circumferential surface of resin part 86 that is covered by metal part 84 (hereinafter referred to as "covered outer circumferential surface 862") is an arcuate surface. The radius of curvature of covered outer circumferential surface 862 is smaller than the radius of curvature of exposed outer circumferential surface 861.

[0070] Examples of metal materials that form the metal portion 84 include stainless steel and aluminum alloy. The metal portion 84 effectively reflects the irradiated light emitted by the rotation sensor 70. The metal portion 84 has an arc portion 841 that follows the outer circumferential surface of the resin portion 86, and a pair of protrusions 842 that protrude from both ends of the arc portion 841 toward the inside of the irradiated portion 80A. The arc portion 841 covers the coated outer circumferential surface 862 of the resin portion 86.

[0071] The radius of curvature of the outer surface of the arc portion 841 is approximately the same as the radius of curvature of the exposed outer peripheral surface 861 of the resin portion 86. The radius of curvature of the outer surface of the arc portion 841 may be different from the radius of curvature of the exposed outer peripheral surface 861 of the resin portion 86. The pair of protrusions 842 are inserted into and engaged with the pair of grooves 83 of the resin portion 86, respectively.

[0072] 7 , the irradiated portion 80A has a first irradiated surface 801 and a second irradiated surface 802 having a lower intensity of reflected light than the first irradiated surface 801. The outer surface of the arc portion 841 of the metal portion 84 is the first irradiated surface 801. The exposed outer peripheral surface 861 of the resin portion 86 is the second irradiated surface 802. Instead of the metal portion 84, a reflective coating or a reflective sheet that easily reflects light may be fixed to the coated outer peripheral surface 862 of the resin portion 86. In this case, the reflective coating or the reflective sheet is the first irradiated surface 801.

[0073] In the circumferential direction of the irradiated portion 80A, the length of the arc portion 841 and the length of the exposed outer peripheral surface 861 of the resin portion 86 are approximately the same. Therefore, approximately half of the outer peripheral surface of the irradiated portion 80A is the arc portion 841, and the remaining half is the exposed outer peripheral surface 861. In other words, half of the circumference of the outer surface of the irradiated portion 80A is the first irradiated surface 801, and the remaining half of the circumference of the outer surface of the irradiated portion 80A is the second irradiated surface 802. Therefore, the extension angle of the first irradiated surface 801 and the second irradiated surface 802 in the circumferential direction of the irradiated portion 80A is approximately 180°. Note that the extension angle of the first irradiated surface 801 in the circumferential direction of the irradiated portion 80A is not limited to approximately 180°. The extension angle of the first irradiated surface 801 may be set, for example, in the range of 160° to 200°.

[0074] As shown in Fig. 8A, when the rotation angle of the second gear 62 is 0°, the irradiated light is reflected by the outer peripheral surface of the metal portion 84 (first irradiated surface 801), and the intensity of the reflected light is high (bright). As shown in Fig. 8C, when the rotation angle of the second gear 62 is 180°, the irradiated light is irradiated onto the resin portion 86 (second irradiated surface 802), and the intensity of the reflected light is low (dark). As shown in Fig. 8B, when the rotation angle of the second gear 62 is 90°, and as shown in Fig. 8D, when the rotation angle of the second gear 62 is 270°, the intensity of the reflected light is intermediate between the high intensity (Fig. 8A) and the low intensity (Fig. 8C).

[0075] The change in the intensity of the reflected light (change in the current value) when the second gear 62 having the irradiated portion 80A rotates once is as shown in Figure 9. The current value changes from high to low once between 0° and 180°, and the current value changes from low to high once between 180° and 360° (a total of two changes). Therefore, the control unit 58 can detect the rotation state of the second gear 62 based on the change in the current value corresponding to the intensity of the reflected light.

[0076] As described above, in the first modified example, the control unit 58 detects a change in the intensity of reflected light (a change in the current value) twice during one rotation of the second gear 62. This makes it possible to achieve a detection resolution in which one detection of a change in the intensity of reflected light corresponds to approximately 0.1 mm of advancement of the plunger 34. The design underlying this is described below with reference to FIG. 3.

[0077] The thread pitch of the feed screw 66 is 0.5 mm. The plunger 34 advances 0.5 mm for one rotation of the fourth gear 64. When the plunger 34 advances 0.5 mm, the second gear 62, on which the irradiated portion 80A is provided, rotates approximately 2.5 times. If a change in the intensity of the reflected light can be detected twice for one rotation of the second gear 62, a change in the intensity of the reflected light can be detected five times every time the plunger 34 advances approximately 0.5 mm. Therefore, a change in the intensity of the reflected light can be detected once every time the plunger 34 advances approximately 0.1 mm. Note that the above design is an example, and the present invention is not limited to the above design values.

[0078] The effects of employing the irradiated portion 80A according to the first modified example shown in FIG. 7 are as follows.

[0079] The outer peripheral surface of the irradiated portion 80A has a first irradiated surface 801 and a second irradiated surface 802 having a lower intensity of reflected light than the first irradiated surface 801. This configuration makes it easy to provide at least two regions having different intensities of reflected light.

[0080] Compared to the irradiated portion 80 having the through-hole 82 shown in FIG. 4 , the irradiated portion 80A shown in FIG. 7 is not affected by reflection on the inner surface of the through-hole 82, allowing for a greater difference in the intensity of reflected light due to differences in the rotation angle. For example, the maximum current value when the irradiated portion 80A rotates once around the axis Ax is 10 times or more the minimum current value. By increasing the current ratio corresponding to the intensity (brightness) of the reflected light by 10 times or more, the accuracy of rotation detection is improved. To further improve the current ratio, the outer surface of the metal portion 84 may be plated to form a surface that is more reflective of light.

[0081] The irradiated portion 80A has a metal portion 84 and a resin portion 86 that reflects light with a lower intensity than the metal portion 84. A first irradiated surface 801 is provided on the metal portion 84, and a second irradiated surface 802 is provided on the resin portion 86. This configuration makes it easy to provide two regions with different reflected light intensities in the irradiated portion 80A.

[0082] The cross section of the irradiated portion 80A perpendicular to the axis Ax has a circular shape. Half of the circumference of the outer surface of the irradiated portion 80A is a first irradiated surface 801, and the remaining half of the circumference of the outer surface of the irradiated portion 80A is a second irradiated surface 802. With this configuration, the areas of high and low intensity of reflected light when the irradiated portion 80A rotates once are approximately equal in size, thereby improving the resolution of rotation detection.

[0083] 10A to 10D, the irradiated portion 80B according to the second modified example has a metal portion 94 and a resin portion 96 that reflects light with a lower intensity than the metal portion 94. The irradiated portion 80B according to the second modified example is a modified version of the irradiated portion 80A according to the first modified example. The irradiated portion 80B has a polygonal cross section perpendicular to the axis Ax of the irradiated portion 80B. Because the irradiated portion 80B in the illustrated example is rectangular, the following description of the metal portion 94 and the resin portion 96 will be given assuming that the irradiated portion 80B is rectangular.

[0084] The metal portion 94 is made of a flat metal plate. The resin portion 96 is formed in a quadrangular prism shape. In order to reduce the intensity of light reflected from the resin portion 96, the resin portion 96 is made of, for example, a resin material that is colored black. The metal portion 94 is fixed to one side of the quadrangular prism-shaped resin portion 96. Instead of the metal portion 94, a reflective coating or a reflective sheet that easily reflects light may be fixed to the resin portion 96.

[0085] The change in the intensity of the reflected light (change in the current value) when the second gear 62 having the irradiated portion 80B rotates once is as shown in Figure 11. The current value changes from high to low once between 0° and 90°, and the current value changes from low to high once between 270° and 360°. Therefore, the control unit 58 can detect the rotation state of the second gear 62 based on the change in the current value corresponding to the intensity of the reflected light.

[0086] In this way, even when the irradiated portion 80B having a polygonal cross-sectional shape is used, the rotation state of the second gear 62, which is a rotating body, can be detected based on the change in the current value corresponding to the intensity of the reflected light.

[0087] Alternatively, metal plates may be fixed to two of the four sides of the rectangular prism-shaped resin part 96. In this case, the two metal plates may be arranged in an L shape on two adjacent sides of the resin part 96, or may be arranged on two opposite sides of the resin part 96.

[0088] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention.

Claims

1. A drug solution administration device comprising: a drug solution container for containing a drug solution and having a drug solution discharge outlet at its tip; a pusher for pushing the drug solution in the drug solution container out of the drug solution discharge outlet; a motor and a rotating body for transmitting the rotation of the motor to the pusher, a drive mechanism for moving the pusher toward the tip; a rotation sensor for detecting the rotation of the rotating body; and a control unit, wherein the rotating body has an irradiated part which is an outer surface along the axis of the rotating body, the rotation sensor has a light-emitting element that emits irradiated light toward the irradiated part and a light-receiving element that receives reflected light from the irradiated part of the rotating body, the irradiated part has at least two regions in the circumferential direction of the rotating body where the intensity of the reflected light differs, and the intensity of the reflected light changes as the irradiated part rotates once around the axis, and the control unit detects the rotation state of the rotating body based on the change in current value corresponding to the intensity of the reflected light.

2. A drug solution administration device as described in claim 1, wherein the outer peripheral surface of the irradiated portion has a first irradiated surface and a second irradiated surface in which the intensity of the reflected light is lower than that of the first irradiated surface.

3. A drug solution administration device as described in claim 2, wherein the irradiated portion has a metal portion and a resin portion in which the intensity of the reflected light is lower than that of the metal portion, the first irradiated surface being provided on the metal portion, and the second irradiated surface being provided on the resin portion.

4. A drug solution administration device as described in claim 2, wherein the cross-sectional shape of the irradiated portion perpendicular to the axis is circular, half the circumference of the outer surface of the irradiated portion is the first irradiated surface, and the remaining half the circumference of the irradiated portion is the second irradiated surface.

5. A drug solution administration device as claimed in claim 1, wherein the cross-sectional shape of the irradiated portion perpendicular to the axis is circular, and the irradiated portion is provided with a through hole passing through the circle in the radial direction.

6. A drug solution administration device as claimed in claim 1, wherein the cross section of the irradiated portion perpendicular to the axis has a polygonal shape.

7. A drug solution administration device according to any one of claims 1 to 6, wherein the maximum value of the current when the irradiated part rotates once around the axis is 10 times or more the minimum value.

8. A drug solution administration device according to any one of claims 1 to 6, wherein the control unit measures the number of rotations of the rotating body based on a change in the current value corresponding to the intensity of the reflected light.

9. A rotation detection device comprising a rotating body and a rotation sensor that detects the rotation of the rotating body, wherein the rotating body has an irradiated portion which is an outer surface along the axis of the rotating body, the rotation sensor has a light emitting element that emits irradiated light toward the irradiated portion and a light receiving element that receives reflected light from the irradiated portion of the rotating body, the irradiated portion has at least two regions in the circumferential direction of the rotating body where the intensity of the reflected light differs, and the intensity of the reflected light changes when the irradiated portion rotates once around the axis.

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