JP6658850B2 - Optical encoder unit and optical encoder - Google Patents

Description

  The present invention relates to an optical encoder unit and an optical encoder that detect an angle using an optical scale.

  2. Description of the Related Art An encoder is used in various types of mechanical devices to detect the position and angle of a movable element. Generally, there are two types of encoders: one for detecting a relative position or angle, and the other for detecting an absolute position or angle. Encoders are classified into optical type and magnetic type. However, the optical type encoder is susceptible to the influence of foreign matter and the like, and is susceptible to the fluctuation of the detected light amount.

  Patent Literature 1 describes a technique capable of reducing the influence of fluctuation in the detected light amount and increasing the resolution.

International Publication No. WO 2013/065737

  In the technique of Patent Literature 1, the influence of the fluctuation of the detected light amount is reduced, but it is required that the rotating shaft of the shaft can be stably rotated even if the size is small.

  The present invention has been made in view of the above, and an object of the present invention is to provide an optical encoder unit and an optical encoder that can stably rotate a rotation axis of a shaft.

  In order to solve the above-described problems and achieve the object, an optical encoder unit includes a light source, an optical scale, and an optical sensor unit that detects incident light transmitted or reflected by the light source light from the light source on the optical scale. A shaft to which the optical scale is attached, and a first bearing and a second bearing rotatably supporting the shaft. The first bearing and the second bearing each include an inner ring, an outer ring, and a rolling element. The inner race of the first bearing and the inner race of the second bearing are preloaded in an axial direction parallel to the rotation axis of the shaft.

  With this structure, the optical encoder unit can stably rotate the rotation axis of the shaft. Further, the optical encoder unit can be reduced in size by reducing a normal mechanism (nut, spring, etc.) for applying a preload to the bearing.

  As a desirable mode of the present invention, the distance between the facing surfaces of the outer race of the first bearing and the outer race of the second bearing is larger than the distance between the facing surfaces of the inner race of the first bearing and the inner race of the second bearing. Preferably, an outer ring spacer for positioning the outer ring of the first bearing and the outer ring of the second bearing is provided. With this configuration, the preload of the bearing is easily maintained.

  As a more desirable mode of the present invention, it is preferred that the outer race of the first bearing and the outer race of the second bearing include a cylindrical outer race-side spacer. According to this configuration, the distance between the position of the shaft supported by the first bearing and the position of the shaft supported by the second bearing is increased, and the inclination of the shaft can be suppressed. , Measurement accuracy can be improved.

  As a desirable mode of the present invention, it is preferred that the inner race of the first bearing and the inner race of the second bearing are further fixed by a cylindrical inner race side spacer. With this configuration, the distance between the inner rings can be guided.

  As a desirable mode of the present invention, it is preferred that the annular and plate-shaped outer ring side spacers are sandwiched between opposed surfaces of the outer ring of the first bearing and the outer ring of the second bearing. With this configuration, the bearing can be downsized in the axial direction. Further, the preload of the bearing is easily maintained.

  As a desirable mode of the present invention, it is preferred to further include a first cylinder surrounding the optical sensor unit and the optical scale. With this configuration, the first cylindrical body is used as a housing, and can be easily assembled.

  As a desirable mode of the present invention, it is preferred that the first cylinder has a light shielding property. With this configuration, external light noise can be suppressed inside the first cylindrical body.

  As a desirable mode of the present invention, it is preferred to have a 2nd cylinder which is arranged in the inner circumference of the 1st cylinder, and covers the outer ring side spacer. With this configuration, the second cylindrical body can support the bearing. For this reason, even if the optical encoder unit is small, assemblability can be improved.

  As a desirable mode of the present invention, the optical encoder is configured to calculate the relative movement amount between the optical scale and the optical sensor unit from the optical encoder unit described above and the light intensity detected by the optical sensor unit. Means. With this configuration, the optical encoder can have high-precision angle measurement accuracy.

  According to the present invention, it is possible to provide an optical encoder unit and an optical encoder that can reduce the influence of the fluctuation of the detected light amount and stably rotate the rotation axis of the shaft.

FIG. 1 is a configuration diagram of the optical encoder unit according to the first embodiment. FIG. 2 is an exploded perspective view of the optical encoder unit according to the first embodiment. FIG. 3 is an external perspective view of the optical encoder unit according to the first embodiment. FIG. 4 is an explanatory diagram illustrating an example of the arrangement of the optical scale and the optical sensor unit. FIG. 5 is a block diagram of the optical encoder according to the first embodiment. FIG. 6 is an explanatory diagram illustrating an example of an optical scale pattern according to the first embodiment. FIG. 7 is an explanatory diagram illustrating an example of the optical sensor unit according to the first embodiment. FIG. 8 is an explanatory diagram illustrating an example of a first light receiving unit of the optical sensor according to the first embodiment. FIG. 9 is an explanatory diagram illustrating an example of a third light receiving unit of the optical sensor according to the first embodiment. FIG. 10 is an explanatory diagram for explaining the separation of the polarization component of the optical sensor according to the first embodiment. FIG. 11 is an explanatory diagram for explaining separation of the polarization component of the optical sensor according to the first embodiment. FIG. 12 is an explanatory diagram for explaining the separation of the polarization component of the optical sensor according to the first embodiment. FIG. 13 is a functional block diagram of the optical encoder according to the first embodiment. FIG. 14 is an explanatory diagram for explaining a rotation angle of the optical scale and a change in light intensity of a polarization component of each light receiving unit according to the first embodiment. FIG. 15 is an explanatory diagram for explaining the relationship between the rotation angle of the optical scale and the Lissajous angle according to the first embodiment. FIG. 16 is a plan view for explaining the light source according to the first embodiment. FIG. 17 is a perspective view of an assembled state schematically illustrating the wiring according to the first embodiment from the light source substrate side without a cover. FIG. 18 is a perspective view of an assembled state schematically illustrating the wiring according to the first embodiment from the sensor substrate side without a cover. FIG. 19 is a cross-sectional view illustrating the bearing according to the first embodiment. FIG. 20 is a perspective view illustrating a bearing according to a modification of the first embodiment. FIG. 21 is a cross-sectional view illustrating a bearing according to a modification of the first embodiment. FIG. 22 is a perspective view illustrating a bearing according to the second embodiment. FIG. 23 is a cross-sectional view illustrating a bearing according to the second embodiment. FIG. 24 is a cross-sectional view illustrating a bearing according to a modification of the second embodiment. FIG. 25 is a perspective view illustrating a bearing according to the third embodiment. FIG. 26 is a cross-sectional view illustrating a bearing according to the third embodiment. FIG. 27 is a cross-sectional view illustrating a bearing according to a modification of the third embodiment. FIG. 28 is a perspective view illustrating a bearing according to the fourth embodiment. FIG. 29 is a cross-sectional view illustrating a bearing according to the fourth embodiment. FIG. 30 is a configuration diagram of an optical encoder unit according to the fifth embodiment. FIG. 31 is an external perspective view of the optical encoder unit according to the fifth embodiment. FIG. 32 is an explanatory diagram illustrating an example of the arrangement of the optical scale and the optical sensor unit according to the sixth embodiment. FIG. 33 is a configuration diagram of an optical encoder unit according to the sixth embodiment. FIG. 34 is a configuration diagram of an optical encoder unit according to a modification of the sixth embodiment.

  An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be appropriately combined.

(Embodiment 1)
FIG. 1 is a configuration diagram of the optical encoder unit according to the first embodiment. FIG. 3 is an external perspective view of the optical encoder unit according to the first embodiment. FIG. 2 is an exploded perspective view of the optical encoder unit according to the first embodiment. FIG. 1 is a schematic sectional view of FIG. FIG. 4 is an explanatory diagram illustrating an example of the arrangement of the optical scale and the optical sensor unit. FIG. 5 is a block diagram of the optical encoder according to the first embodiment. FIG. 6 is an explanatory diagram illustrating an example of an optical scale pattern according to the first embodiment. The optical encoder unit 31 includes the rotor 10 having the shaft 12 connected to a rotating machine such as a motor, the stator 20, and an optical sensor unit 35 capable of reading a signal pattern.

  The rotor 10 has an optical scale 11 which is a member having a disk shape shown in FIG. 6 or a polygonal shape (octagon in FIG. 2) shown in FIG. The optical scale 11 is formed of, for example, silicon, glass, a polymer material, or the like. The optical scale 11 may be annular or hollow. The optical scale 11 shown in FIG. 6 has a signal track T1 on one plate surface. Further, the rotor 10 has a shaft 12 attached to the other plate surface with respect to the plate surface to which the optical scale 11 is attached. Even if the optical scale 11 is inclined, the optical scale 11 does not affect the polarization separation function when the inclination angle is small. That is, even if the optical scale 11 is inclined with respect to a plane orthogonal to the rotation center Zr, it functions as a polarization splitting element.

  As shown in FIG. 3, the stator 20 includes a cylindrical cover 21 and a sensor substrate 23. The cylindrical cover 21 is fixed so as to cover the side surface of the sensor substrate 23 independently of the rotor 10, and the rotor 10 can rotate relative to the stator 20. The cover 21 is made of a light-shielding member that surrounds the bearing 26, the shaft 12, the optical scale 11 attached to an end of the shaft 12, and the optical sensor unit 35. For this reason, the inside of the cover 21 can suppress external light noise. The cover 21 is not limited to a cylinder, and may be a prism having an outer diameter of a triangle, a square, a hexagon, an octagon, or the like, as long as it is cylindrical.

  The cover 21 rotatably supports the shaft 12 via a bearing 26. The inner periphery of the cover 21 is fixed to the outer ring of the bearing 26, and the outer periphery of the shaft 12 is fixed to the inner ring of the bearing 26. The structure of the bearing 26 will be described later. When the shaft 12 rotates by rotation from a rotating machine such as a motor, the optical scale 11 rotates about the rotation center Zr in conjunction with the shaft 12. The optical sensor unit 35 is fixed to the sensor substrate 23. When the rotor 10 rotates, the signal track T1 of the optical scale 11 moves relatively to the optical sensor unit 35.

  As shown in FIGS. 1 and 2, the optical encoder unit 31 has a connector CNT that is an input / output terminal fixed to the flexible substrate 23FP. The connector CNT can supply power to the conductor wiring 25 provided on the surface or inside of the flexible substrate 23FP, and can output a detection signal from the optical sensor unit 35 to the outside via the preamplifier AMP.

  In the preamplifier AMP, the optical sensor unit 35 is directly stacked on a packaged amplifier. Since the preamplifier AMP is built in the cover 21, the durability can be improved. The preamplifier AMP may have a light receiving element and an amplifier circuit mounted on a bare chip. In the preamplifier AMP, the light receiving element and the amplifier circuit may be integrally formed by a semiconductor process.

  Wirings and circuits connected to the wiring 25 are wired on the surface and inside of the sensor substrate 23, and along the inside of the cover 21 directly with the wiring 25 or via the wiring and the circuit connected to the wiring 25. One end of the provided wiring 24 is electrically connected. For this reason, the conductor wiring 25 provided on the surface or inside of the sensor substrate 23 and the wiring 24 provided along the inside of the cover 21 are connected to the connector CNT, the preamplifier AMP, the optical sensor unit 35, and the light source 41. Connected appropriately.

  The optical encoder unit 31 may have a cover member 29 attached from the back side to protect the flexible substrate 23FP. It is more preferable that the lid member 29 is a light-shielding insulator.

  When the shaft 12 of the rotor 10 described above rotates, the optical scale 11 moves relative to the optical sensor unit 35, for example, in the R direction, as shown in FIG. In the optical scale 11, the polarization direction Pm of the polarizer in the plane is oriented in a predetermined direction, and the polarization direction Pm changes by rotation. The optical sensor unit 35 can receive the incident light (transmitted light) 73 that is transmitted from the light source 41 of the light source 41 and enters the optical scale 11, and can read the signal track T1 of the optical scale 11 shown in FIG. .

  In the optical encoder unit 31 according to the first embodiment, the light source 41 is fixed to the surface of the light source substrate 42. The light source substrate 42 has a hole 42H through which the shaft 12 penetrates, and wirings 24, 24, 24D, and 24D to be described later such that the sensor substrate 23 and the optical substrate 42 face each other with the optical scale 11 therebetween. It is supported by. The light source 41 is, for example, a light emitting diode or a semiconductor laser light source, and will be described later in detail.

  The optical encoder 2 includes the above-described optical encoder unit 31 and the arithmetic unit 3, and the optical encoder unit 31 and the arithmetic unit 3 are connected as shown in FIG. The arithmetic unit 3 is connected to a control unit 5 of a rotating machine such as a motor.

  The optical encoder 2 uses the optical sensor unit 35 to detect incident light 73 that is transmitted through the light source light 71 and enters the optical scale 11. The arithmetic unit 3 calculates the relative position between the rotor 10 of the optical encoder unit 31 and the optical sensor unit 35 from the detection signal of the optical sensor unit 35, and uses the information on the relative position as a control signal to control a rotating machine such as a motor. Output to the unit 5.

  The arithmetic unit 3 is a computer such as a personal computer (PC), and has an input interface 4a, an output interface 4b, a CPU (Central Processing Unit) 4c, a ROM (Read Only Memory) 4d, and a RAM (Random Access Memory). 4e and an internal storage device 4f. The input interface 4a, the output interface 4b, the CPU 4c, the ROM 4d, the RAM 4e, and the internal storage device 4f are connected by an internal bus. The arithmetic unit 3 may be configured by a dedicated processing circuit.

  The input interface 4a receives an input signal from the optical sensor unit 35 of the optical encoder unit 31 and outputs the signal to the CPU 4c. The output interface 4b receives a control signal from the CPU 4c and outputs the control signal to the control unit 5.

  A program such as a BIOS (Basic Input Output System) is stored in the ROM 4d. The internal storage device 4f is, for example, an HDD (Hard Disk Drive) or a flash memory, and stores an operating system program and an application program. The CPU 4c realizes various functions by executing programs stored in the ROM 4d and the internal storage device 4f while using the RAM 4e as a work area.

  The internal storage device 4f, which is a storage unit, stores a database in which a polarization axis, which will be described later, of the optical scale 11 is associated with an output of a sensor of the optical sensor unit 35. Alternatively, the internal storage device 4f stores a database in which the value of the distance D shown in FIG.

  In the signal track T1 shown in FIG. 6, an array of thin metal wires (wires) g called a wire grid pattern is formed on the optical scale 11 shown in FIG. The optical scale 11 has adjacent metal thin lines g linearly arranged in parallel as signal tracks T1. For this reason, the optical scale 11 has the same polarization axis regardless of the position where the light source light 71 is irradiated, and the polarization direction of the polarizer in the plane is in one direction.

  In addition, the optical scale 11 having the fine metal wire g called a wire grid pattern can increase the heat resistance of the optical scale 11 as compared with a light-induced polarizing plate. In addition, since the optical scale 11 has a line pattern that does not locally cross, the optical scale 11 can be an optical scale with high accuracy and few errors. Further, since the optical scale 11 can be manufactured stably by collective exposure or nanoimprint technology, it can be an optical scale with high accuracy and few errors. Note that the optical scale 11 may be a light-induced polarizing plate.

  The plurality of thin metal wires g are arranged without intersecting. Between the adjacent thin metal wires g is a transmission area gl through which all or a part of the light source light 71 can be transmitted. When the width of the thin metal wire g and the distance between adjacent thin metal wires g, that is, the width of the thin metal wire g and the width of the transmission region gl are sufficiently smaller than the wavelength of the light source light 71 of the light source 41, the optical scale 11 Can be polarized and separated. For this reason, the optical scale 11 has a polarizer having a uniform polarization direction (polarization axis) Pm in the plane. In the optical scale 11, the polarization axis of the incident light incident on the optical sensor unit 35 changes in the rotating circumferential direction according to the rotation of the optical scale 11. In the first embodiment, the change of the polarization axis is repeated two times for one rotation of the optical scale 11.

  The optical scale 11 does not need to make segments having different polarization directions smaller. Since the optical scale 11 has a uniform polarization axis Pm, there is no boundary between regions having different polarization axes Pm, and disturbance of the polarization state of the incident light 73 due to this boundary can be suppressed. The optical encoder 2 according to the first embodiment can reduce the possibility of causing erroneous detection or noise.

  FIG. 7 is an explanatory diagram illustrating an example of the optical sensor unit according to the first embodiment. FIG. 8 is an explanatory diagram illustrating an example of a first light receiving unit of the optical sensor according to the first embodiment. FIG. 9 is an explanatory diagram illustrating an example of a third light receiving unit of the optical sensor according to the first embodiment. As shown in FIGS. 4 and 7, the optical sensor unit 35 includes a first light receiving unit PD1 having a polarizing layer PP1 and a second light receiving unit PD2 having a polarizing layer PP2 on a surface 30b of the unit base 30. It includes a third light receiving unit PD3 having a polarizing layer PP3 and a fourth light receiving unit PD4 having a polarizing layer PP4. As shown in FIG. 7, the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 are equidistant from the arrangement center S0 of the surface 30b of the unit base material 30 in plan view. Are located.

  As shown in FIG. 4, the light source light 71 emitted from the light source 41 passes through the above-described optical scale 11 and passes as the incident light 73 through the polarizing layers PP1, PP2, PP3, and PP4. Then, the light enters the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4.

  As shown in FIG. 4, it is preferable that the distances from the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 to the arrangement center S0 be equal. With this structure, the calculation load on the CPU 4c as the calculation means can be reduced.

  Further, the first light receiving unit PD1 is disposed at a point symmetric position with respect to the third light receiving unit PD3 via the arrangement center S0, and the second light receiving unit PD2 is disposed at a point symmetric position with respect to the fourth light receiving unit PD4 via the arrangement center S0. Are located in The first light receiving unit PD1 is arranged at a distance W from the third light receiving unit PD3 via the arrangement center S0, and the second light receiving unit PD2 is arranged at a distance W from the fourth light receiving unit PD4 via the arrangement center S0. Have been. Note that there is a width w of the first light receiving unit PD1, the third light receiving unit PD3, the second light receiving unit PD2, and the fourth light receiving unit PD4, and there is a restriction that the distance W does not become smaller than the width 2w. In the first embodiment, the imaginary axis on the surface 30b of the unit base 30 passing through the first light receiving unit PD1, the arrangement center S0, and the third light receiving unit PD3 is set as the x-axis, and the second light receiving unit PD2, the arrangement center S0, and the The imaginary axis on the surface 30b of the unit base material 30 passing through the four light receiving units PD4 is defined as the y-axis. In FIG. 7, the x axis is orthogonal to the y axis on the surface of the unit substrate 30. As shown in FIG. 4, the distance between the emission surface of the light source 41 and the arrangement center S0 is D. An xy plane defined by the x-axis and the y-axis is orthogonal to the z-axis connecting the emission surface of the light source 41 and the arrangement center S0.

  As shown in FIG. 4, when viewed in a plan view from the z-axis direction, each of the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 is arranged around the light source 41. ing. It is preferable that the distance from each of the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 to the arrangement center S0 is equal. With this structure, the calculation load on the CPU 4c as the calculation means can be reduced.

  As shown in FIG. 8, the first light receiving unit PD1 includes a silicon substrate 34, a light receiving unit 37, and a first polarizing layer 39a. As shown in FIG. 9, the third light receiving unit PD3 includes a silicon substrate 34, a light receiving unit 37, and a second polarizing layer 39b. For example, the silicon substrate 34 is an n-type semiconductor, and the light receiving unit 37 is a p-type semiconductor, and the silicon substrate 34 and the light receiving unit 37 can constitute a photodiode formed by a PN junction. The first polarizing layer 39a and the second polarizing layer 39b can be formed by a light-induced polarizing layer or a wire grid pattern in which thin metal wires are arranged in parallel. The first polarizing layer 39a separates incident light 73 incident on the optical scale 11 shown in FIG. 2 from the light source light 71 into a first polarization direction, and the second polarizing layer 39b separates the incident light into a second polarization direction. To separate. It is preferable that the polarization axis of the first separated light and the polarization axis of the second separated light are relatively different from each other by 90 °. With this configuration, the CPU 4c of the arithmetic unit 3 can easily calculate the polarization angle.

  Similarly, with reference to FIGS. 8 and 9, the second light receiving unit PD2 includes a silicon substrate 34, a light receiving unit 37, and a first polarizing layer 39a. Further, as shown in FIG. 9, the fourth light receiving unit PD4 includes a silicon substrate 34, a light receiving unit 37, and a second polarizing layer 39b. For example, the silicon substrate 34 is an n-type semiconductor, and the light receiving unit 37 is a p-type semiconductor, and the silicon substrate 34 and the light receiving unit 37 can constitute a photodiode formed by a PN junction. The first polarizing layer 39a and the second polarizing layer 39b can be formed by a light-induced polarizing layer or a wire grid pattern in which thin metal wires are arranged in parallel. The first polarizing layer 39a separates incident light 73 incident on the optical scale 11 shown in FIG. 2 from the light source light 71 into a first polarization direction, and the second polarizing layer 39b separates the incident light into a second polarization direction. To separate. It is preferable that the polarization axis of the first separated light and the polarization axis of the second separated light are relatively different from each other by 90 °. With this configuration, the CPU 4c of the arithmetic unit 3 can easily calculate the polarization angle.

  The first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 receive the incident light 73 via the polarization layers PP1, PP2, PP3, and PP4 that separate the light into different polarization directions. . For this reason, it is preferable that the polarization axis separated by the polarization layer PP1 and the polarization axis separated by the polarization layer PP2 are relatively different from each other by 45 °. It is preferable that the polarization axis separated by the polarizing layer PP2 and the polarization axis separated by the polarizing layer PP3 differ from each other by 45 °. It is preferable that the polarization axis separated by the polarizing layer PP3 and the polarization axis separated by the polarizing layer PP4 are relatively different by 45 °. It is preferable that the polarization axis separated by the polarizing layer PP4 and the polarization axis separated by the polarizing layer PP1 are relatively different from each other by 45 °. With this configuration, the CPU 4c of the arithmetic unit 3 can easily calculate the polarization angle.

  FIGS. 10, 11, and 12 are explanatory diagrams illustrating the separation of the polarization component of the angle sensor according to the first embodiment. As shown in FIG. 10, incident light polarized in the polarization direction Pm by the signal track T1 of the optical scale 11 enters. In FIG. 10, there are a foreign substance D1 and a foreign substance D2 in the sensing range. The polarization direction Pm of the incident light can be expressed by the light intensity PI (-) of the component in the first polarization direction and the light intensity PI (+) of the component in the second polarization direction. As described above, the first polarization direction and the second polarization direction are preferably directions different from each other by 90 °, such as a + 45 ° component and a −45 ° component with respect to the reference direction. . In FIG. 10, FIG. 11 and FIG. 12, the axial direction of the wire grid is shown parallel to the plane of the paper. Does not affect the function of separation. That is, the optical scale 11 functions as a polarization splitting element even if it is inclined with respect to the rotation axis.

  As shown in FIG. 11, the first light receiving unit PD1 detects the incident light via the first polarizing layer 39a that separates the incident light into the first polarization direction, and thus the light intensity PI (−) of the component in the first polarization direction. ) Is detected. As shown in FIG. 12, since the third light receiving unit PD3 detects the incident light via the second polarizing layer 39b that separates the incident light into the second polarization direction, the light intensity PI (+) of the component in the second polarization direction is detected. ) Is detected. Similarly, as shown in FIG. 11, the second light receiving unit PD2 detects the incident light through the first polarizing layer 39a that separates the incident light into the first polarization direction, and thus the light intensity of the component in the first polarization direction. PI (-) is detected. As shown in FIG. 12, the fourth light receiving unit PD4 detects the incident light via the second polarizing layer 39b that separates the incident light into the second polarization direction, and thus the light intensity PI (+) of the component in the second polarization direction. ) Is detected.

  FIG. 13 is a functional block diagram of the optical encoder according to the first embodiment. FIG. 14 is an explanatory diagram for explaining a rotation angle of the optical scale and a change in light intensity of a polarization component of each light receiving unit according to the first embodiment. As shown in FIG. 13, the light source 41 emits light based on the reference signal, and irradiates the optical scale 11 with light source light 71. The incident light 73 that is transmitted light is received by the optical sensor unit 35 that is a light receiving unit. As shown in FIG. 13, the light receiving signal amplified by the preamplifier AMP is subjected to differential operation processing by a differential operation circuit DS.

  The differential operation circuit DS includes a light intensity PI (−) of a component in the first polarization direction (first separated light), which is a detection signal of the optical sensor unit 35, and a component (second separation) in the second polarization direction. Light intensity PI (+). The respective outputs of the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 corresponding to the light intensity PI (-) and the light intensity PI (+) are, for example, As shown in FIG. 14, the light intensities I1, I2, I3, and I4 are shifted in phase according to the rotation of the optical scale 11.

  The differential operation circuit DS converts the light intensity PI (−) of the component in the first polarization direction and the light intensity PI (+) of the component in the second polarization direction into an optical signal according to Expressions (1) and (2). The differential signals Vc and Vs depending on the rotation of the scale 11 are calculated.

  As described above, the differential operation circuit DS calculates the sum [I1 + I3] of the light intensities and the difference [I1-I3] of the light intensities based on the light intensities I1 and I3, and calculates the light intensity difference [I1]. −I3] is divided by the sum [I1 + I3] of the light intensities to calculate a differential signal Vc. Further, the differential operation circuit DS calculates the sum [I2 + I4] of the light intensities and the difference [I2-I4] of the light intensities based on the light intensities I2 and I4, and calculates the difference [I2-I4] of the light intensities. ] Is divided by the sum [I2 + I4] of the light intensities to calculate the differential signal Vs. The differential signals Vc and Vs calculated by the equations (1) and (2) do not include parameters affected by the light intensity of the light source light 71, and the output of the optical encoder unit 31 is an optical sensor The influence of the distance between the unit 35 and the optical scale 11, the variation of the light intensity of the light source 41, and the like can be reduced. Then, as shown in Expression (1), the differential signal Vc is a function of the rotation angle β of the polarization axis of the optical scale 11 (hereinafter referred to as polarization angle) which is the rotation angle of the optical scale 11. However, when the automatic power control (APC) for controlling the light amount of the light source to be constant is provided, the above-described division is unnecessary.

  As shown in FIG. 13, the differential signals Vc and Vs are input to the filter circuit NR, and noise is removed. Next, the multiplication circuit AP calculates the Lissajous pattern shown in FIG. 15 from the differential signals Vc and Vs, and can specify the absolute angle of the rotation angle of the rotor 10 rotated from the initial position. Since the differential signals Vc and Vs are differential signals having a λ / 4 phase shift, a Lissajous pattern in which the horizontal axis represents the cosine curve of the differential signal Vc and the vertical axis represents the sine curve of the differential signal Vs. After the calculation, the Lissajous angle is determined according to the rotation angle. For example, the Lissajous pattern shown in FIG. 15 makes two revolutions when the rotor 10 makes one rotation. The arithmetic unit 3 has a function of storing whether the rotational position of the optical scale 11 is in a range of 0 ° or more and less than 180 ° or in a range of 180 ° or more and less than 360 °. As described above, the optical encoder 2 stores in the storage device whether the rotational position of the optical scale 11 is in the range of 0 ° or more and less than 180 ° or in the range of 180 ° or more and less than 360 °, and reads out the information at the time of startup. It has a calculating means and calculates an absolute movement amount between the optical scale 11 and the optical sensor unit 35. Thereby, the optical encoder 2 can be an absolute encoder that can calculate the absolute position of the rotor 10. In addition to the configuration shown in FIG. 13, the optical encoder unit 31 may have a configuration including the optical sensor unit 35 and the preamplifier AMP.

  FIG. 16 is a plan view for explaining the light source according to the first embodiment. The light source 41 shown in FIG. 16 is a package in which a light emitting diode 41, a laser light source such as a vertical cavity surface emitting laser, and a light emitting device 41U such as a filament are packaged. The light emitting device 41U uses a surface emitting light source.

  The light source 41 includes a base substrate 41F, a penetrating conductive layer 41H embedded in the through hole SH, an external electrode 41P electrically connected to the penetrating conductive layer 41H, and a light emitting device 41U mounted on the base substrate 41F. The light emitting device includes a bonding wire 41W that electrically connects the light emitting device 41U and the through conductive layer 41H, a sealing resin 41M that protects the light emitting device 41U, and a light shielding film 41R.

  The light-shielding film 41R of the light source 41 functions as a stop for the light source light 71 that narrows the light source light 71 emitted by the light emitting device 41U to the range of the emission surface 41T. The exit surface 41T may not have a lens surface. The optical encoder unit 31 according to the first embodiment can use a light source 41 without a lens. The SN ratio can be improved by reducing the distance between the light emitting surface of the light source 41 and the optical sensor unit 35. The distance to each of the first light receiving unit PD1, the second light receiving unit PD2, the third light receiving unit PD3, and the fourth light receiving unit PD4 can be arranged in a range where light can be received by reducing the influence of light diffused by the light source 41. For this reason, the measurement accuracy of the optical encoder unit 31 and the optical encoder 2 is improved.

  FIG. 17 is a perspective view of an assembled state schematically illustrating the wiring according to the first embodiment from the light source substrate side without a cover. FIG. 18 is a perspective view of an assembled state schematically illustrating the wiring according to the first embodiment from the sensor substrate side without a cover. As shown in FIGS. 17 and 18, the four wirings 24, 24, 24 are arranged so that the light source substrate 42 on which the light source 41 is mounted on one side and the sensor substrate 23 on which the optical sensor unit 35 is mounted on one side are opposed to each other. 24D, fixed at 24D.

  The wirings 24 and 24 are metal pillars that are prisms or cylinders such as a triangular prism, a quadrangular prism, a hexagonal prism, and an octagonal prism. The wirings 24, 24 are formed by drawing a metal having conductivity, such as iron, iron alloy, copper, copper alloy, aluminum, or aluminum alloy, to form a linear columnar body. The wirings 24D, 24D are metal pillars that are prisms or cylinders such as triangular prisms, quadrangular prisms, hexagonal prisms, and octagonal prisms. The wirings 24, 24, 24D, and 24D are formed into linear pillars by drawing metal having conductivity, such as iron, iron alloy, copper, copper alloy, aluminum, and aluminum alloy.

  The wirings 24, 24 are fixed at bonding portions 23M so as to be electrically connected to the wiring on the surface or inside of the sensor substrate 23 by metal bonding such as soldering. Similarly, the wirings 24, 24 are fixed at the joints 42M so as to be electrically connected to the surface of the light source substrate 42 or the internal wirings by metal bonding such as soldering. The wiring on the surface or inside of the light source substrate 42 is electrically connected to the light source 41. The power supplied from the flexible board 23FP is supplied to the light source 41 through the wiring 25 of the flexible board 23FP, the wirings 24 and 24 on the surface or inside of the sensor board 23, and the wiring on the surface or inside of the light source board 42. Thus, the wirings 24, 24 are fixed to the sensor substrate 23 (first substrate), support the light source substrate 42 (second substrate), and supply power for the light source 41 to emit light.

  The wirings 24D, 24D are fixed to the sensor substrate 23 at a joint 23M by metal joining such as soldering. Similarly, the wirings 24D, 24D are fixed to the light source substrate 42 at the joints 42M so as to be electrically connected to each other by metal joining such as soldering. The wirings 24D, 24D are dummy wirings that do not contribute to power supply to the light source 41.

  When the vertical relationship between the sensor substrate 23 (first substrate) and the light source substrate 42 (second substrate) is exchanged, the wirings 24, 24, 24D, 24D are fixed to the light source substrate 42 (second substrate). Then, it is also possible to support the sensor substrate 23 (first substrate) and supply power for the light source 41 to emit light. In this case, the wirings 24D, 24D are transmission wirings of the detection signal of the optical sensor unit 35.

  Since the light source substrate 42 is an annular plate member, there is a possibility that the light source substrate 42 is inclined only by the wirings 24, 24. Since the wirings 24, 24, 24D, and 24D are columnar bodies having the same length, they are arranged at the same distance from the rotation center Zr of the optical scale 11 so that the angles between adjacent columnar bodies and the rotation center Zr are equal. By doing so, the load of the light source substrate 42 applied to the wirings 24, 24, 24D, 24D becomes uniform, and the balance is improved. Thereby, the accuracy of the direction of the light emitted from the light source 41 can be improved. The number of wires 24, 24 may be any number as long as the number of light sources 41 is turned on.

(bearing)
FIG. 19 is a cross-sectional view illustrating the bearing according to the first embodiment. In the optical encoder unit 31, the play of the rotating shaft of the shaft 12 and the rotational vibration affect the detection accuracy. For example, as described above, the cover 21 rotatably supports the shaft 12 via the bearing 26. Since the bearing 26 is fixed to the inner peripheral surface of the cover, there is no space for mounting a mechanism for suppressing the bearing 26 from tilting the shaft 12. Furthermore, the above-mentioned optical encoder unit 31 can be downsized, but it is difficult to use a normal mechanism (nut, spring, etc.) for applying a preload to the bearing 26.

  Therefore, as shown in FIGS. 2 and 19, the bearing 26 includes a first bearing 26A and a second bearing 26B. The first bearing 26A and the second bearing 26B are arranged at different positions for supporting the shaft 12 in the axial direction with the direction parallel to the rotation center Zr as the axial direction. As shown in FIG. 19, the first bearing 26A includes an inner ring 26Aa, an outer ring 26Ab, and a rolling element 26AR, and is assembled in a ring around the rotation center Zr. The second bearing 26B includes an inner ring 26Ba, an outer ring 26Bb, and a rolling element 26BR, and is assembled in a ring around the rotation center Zr.

  The shaft 12 has a small diameter portion 12A having a reduced diameter and a constant diameter, and has an abutment surface 12u due to a step at a boundary between the small diameter portion 12A and the large diameter portion. Although the shaft 12 is exemplified by a solid material, the shaft 12 is not limited to this, and may be a hollow shaft having a concave portion on the opposite end surface of the optical scale 11, or a female screw may be formed in the hollow inner periphery of the concave portion. . Further, the shaft 12 may be a tubular shaft having a through-hole penetrating in the axial direction. The outer periphery of the shaft 12 may be subjected to processing such as external threads or splines. As described above, the shaft 12 may be subjected to processing for facilitating connection with another member.

  The inner ring 26Aa of the first bearing 26A is inserted into the abutting surface 12u so as to be in contact with the axial direction. The outer race 26Ab of the first bearing 26A includes a flange-like flange 26At that protrudes radially in an annular shape. The outer ring 26Bb of the second bearing 26B includes a flange-shaped flange 26Bt that projects radially in an annular shape. The first bearing 26A and the second bearing 26B are opposed in the axial direction, and a cylindrical spacer 26S is fitted between the flange 26At and the flange 26Bt. With this structure, the first bearing 26A, the second bearing 26B, and the spacer 26S can be easily aligned. When the outer periphery of the spacer 26S is fitted, it has the same diameter as the outer periphery in the radial direction of the flange portion 26At and the flange portion 26Bt, so that unevenness can be reduced on the outer periphery of the bearing 26, as shown in FIG. Insertion into the cover 21 is facilitated. When the spacer 26S is fixed with an adhesive at the flange 26At, the flange 26Bt, the outer periphery 26Au of the outer ring 26Ab, and the outer periphery 26Bu of the outer ring 26Bb, the bonding area increases, and the space between the first bearing 26A and the second bearing 26B is increased. The bonding strength is reinforced.

  In the bearing 26 according to the first embodiment, a gap 26n is generated between the inner ring 26Aa and the inner ring 26Ba. In FIG. 19, the illustration of the cover 21 is omitted, but in a state where the axial positions of the cover 21 and the shaft 12 are fixed with a jig, and the outer ring 26Bb of the second bearing 26B is connected to the first bearing 26A and the second bearing 26B. The two bearings 26B are fixed. The cover 21 and the outer ring 26Ab and the outer ring 26Bb are fixed by bonding or press fitting. For the adhesive fixing, an epoxy adhesive, an adhesive for screw fixing, a thermosetting adhesive, a UV curing adhesive, or the like can be used. Then, by the bonding process, the shaft 12 becomes a stable rotation axis without play.

  The small diameter portion 12A is fitted with the inner ring 26Aa and the inner ring 26Ba, and is fixed by bonding or press fitting. For example, in the case of bonding, an adhesive is interposed between the small diameter portion 12A and the inner ring 26Aa and the inner ring 26Ba. Note that an epoxy adhesive, an adhesive for screw fixing, a thermosetting adhesive, a UV curing adhesive, or the like can be used for the adhesive fixing. Further, in the bearing 26 according to the first embodiment, the inner ring 26Ba of the second bearing 26B is pressed in the axial direction toward the abutting surface 12u in the direction P shown in FIG. 19, and the inner ring 26Aa exerts a reaction force from the abutting surface 12u. 19 in the PB direction. As a result, since the outer ring 26Ab and the outer ring 26Bb are constrained in the axial direction by the spacer 26S, the first bearing 26A and the second bearing 26B receive a preload so as to reduce the gap 26n, and are moved in the axial direction of the shaft 12. Preloaded. In the bearing 26 according to the first embodiment, the adhesive between the small diameter portion 12A, the inner ring 26Aa, and the inner ring 26Ba is solidified and fixed in a preloaded state. By using the bearing 26 fixed by the adhesive, it is possible to easily assemble various sensors and small encoders having the shaft 12 (rotary shaft). Note that an epoxy adhesive, an adhesive for screw fixing, a thermosetting adhesive, a UV curing adhesive, or the like can be used for the adhesive fixing. Then, by the bonding process, the shaft 12 becomes a stable rotation axis without play.

  With this structure, even if the bearing 26 is fixed to the inner peripheral surface of the cover 21, the bearing 26 can suppress the inclination of the shaft 12. Further, the outer diameter of the cover 21 is reduced to 2 mm or more and 20 mm or less, and the diameter of the shaft is set to 0.6 mm or more and 5 mm or less, so that the optical encoder unit 31 can be downsized. Further, a normal mechanism (nut, spring, etc.) for applying a preload to the bearing 26 becomes unnecessary.

  FIG. 20 is a perspective view illustrating a bearing according to a modification of the first embodiment. FIG. 21 is a cross-sectional view illustrating a bearing according to a modification of the first embodiment. As shown in FIGS. 20 and 21, the spacer 26S can be larger than the axial thickness of the first bearing 26A and the second bearing 26B. With this structure, even if the bearing 26 is fixed to the inner peripheral surface of the cover 21, the bearing 26 can suppress the inclination of the shaft 12. The gap 26N between the inner ring 26Aa and the inner ring 26Ba is larger than the above-described gap 26n, and a light source, an optical scale, an optical sensor unit 35, and the like can be disposed inside the gap 26N.

  As described above, in the bearing 26 according to the modified example of the first embodiment, the inner ring 26Ba of the second bearing 26B is pressed in the axial direction toward the abutting surface 12u in the P direction shown in FIG. From the PB direction shown in FIG. As a result, since the outer ring 26Ab and the outer ring 26Bb are constrained in the axial direction by the spacer 26S, the first bearing 26A and the second bearing 26B receive a preload so as to reduce the gap 26N, and the axial direction of the shaft 12 Preloaded.

  As described above, the optical encoder unit 31 according to the first embodiment includes a light source 41, an optical scale 11, an optical sensor unit 35 that detects incident light transmitted from the light source 41 to the optical scale 11, and A shaft 12 to which the optical scale 11 is attached, and a first bearing 26A and a second bearing 26B that rotatably support the shaft 12 are provided. The first bearing 26A and the second bearing 26B each include an inner ring, an outer ring, and a rolling element. The inner ring of the first bearing 26A and the inner ring of the second bearing 26B are preloaded in the axial direction of the shaft 12. With this structure, the optical encoder unit 31 can stably rotate the rotation axis of the shaft. Since the rotation shaft can be rotated stably, the optical encoder unit 31 according to the first embodiment can suppress the whirling or parallel movement of the shaft. In addition, the optical encoder unit 31 can be reduced in size by reducing a normal mechanism (nut, spring, etc.) for applying a preload to the bearing.

(2nd Embodiment)
FIG. 22 is a perspective view illustrating a bearing according to the second embodiment. FIG. 23 is a cross-sectional view illustrating a bearing according to the second embodiment. The same members as those described above are denoted by the same reference numerals, and redundant description will be omitted. In the bearing 26 according to the second embodiment, the outer ring 26Ab and the outer ring 26Bb do not include the flange 26At and the flange 26Bt described in the first embodiment. Therefore, inexpensive first bearing 26A and second bearing 26B can be used.

  In the bearing 26 according to the second embodiment, an outer ring-side spacer 26Pb is sandwiched between axially opposed surfaces of the outer ring 26Ab of the first bearing 26A and the outer ring 26Bb of the second bearing 26B. The outer race side spacer 26Pb is an annular and plate-shaped member surrounding the center of the shaft 12 (small-diameter portion 12A), and has an axial thickness of 0.02 mm or more and 1.0 mm or less.

  In the bearing 26 according to the second embodiment, an inner ring side spacer 26Pa is sandwiched between axially opposed surfaces of the inner ring 26Aa of the first bearing 26A and the inner ring 26Ba of the second bearing 26B. The inner ring-side spacer 26Pa is a ring-shaped and plate-shaped member surrounding the center of the shaft 12 (small diameter portion 12A), and has an axial thickness of 0.01 mm or more and 0.8 mm or less. The thickness is 10% or more and 80% or less of the thickness.

  The shaft 12 has a small diameter portion 12A having a reduced diameter and a constant diameter, and has an abutment surface 12u due to a step at a boundary between the small diameter portion 12A and the large diameter portion. The inner ring 26Aa of the first bearing 26A is inserted into the abutting surface 12u so as to be in contact with the axial direction. The small diameter portion 12A is fitted with the inner ring 26Aa and the inner ring 26Ba, and is fixed by bonding or press fitting. Further, in the bearing 26 according to the second embodiment, the inner ring 26Ba of the second bearing 26B is pressed in the axial direction toward the abutting surface 12u in the P direction shown in FIG. 23, and the inner ring 26Aa exerts a reaction force from the abutting surface 12u. 23 in the PB direction. Thus, since the outer ring 26Ab and the outer ring 26Bb are constrained in the axial direction by the outer ring-side spacer 26Pb, the inner ring-side spacer 26Pa is plastically deformed to be compressed in the axial direction, and the first bearing 26A and the second bearing 26B Receives a preload, and is preloaded in the axial direction of the shaft 12. If the thickness of the inner ring side spacer 26Pa is smaller (thinner) than the thickness of the outer ring side spacer 26Pb, the first bearing 26A and the second bearing 26B can easily maintain the preload. In the bearing 26 according to the second embodiment, the amount of preload can be controlled by the difference in thickness between the outer ring side spacer 26Pb and the inner ring side spacer 26Pa, and the management of the manufacturing process is facilitated.

  FIG. 24 is a cross-sectional view illustrating a bearing according to a modification of the second embodiment. The bearing 26 according to the modification of the second embodiment is different from the bearing 26 according to the second embodiment in that an inner ring-side spacer 26Pa is provided on an axially opposed surface between the inner ring 26Aa of the first bearing 26A and the inner ring 26Ba of the second bearing 26B. Is not sandwiched. Thereby, a gap 26n is generated between the inner ring 26Aa and the inner ring 26Ba. In the bearing 26 according to the modification of the second embodiment, the inner ring 26Ba of the second bearing 26B is pressed in the axial direction toward the abutting surface 12u in the direction P shown in FIG. 24, and the inner ring 26Aa applies a reaction force from the abutting surface 12u. It is received in the PB direction shown in FIG. As a result, the outer ring 26Ab and the outer ring 26Bb are constrained in the axial direction by the outer ring spacer 26Pb, so that the first bearing 26A and the second bearing 26B receive a preload so that the gap 26n is reduced, and the shaft 12 Preloaded in the direction.

(Third embodiment)
FIG. 25 is a perspective view illustrating a bearing according to the third embodiment. FIG. 26 is a cross-sectional view illustrating a bearing according to the third embodiment. The same members as those described above are denoted by the same reference numerals, and redundant description will be omitted.

  In the bearing 26 according to the third embodiment, the outer ring 26Ab and the outer ring 26Bb do not include the flange 26At and the flange 26Bt described in the first embodiment. Therefore, inexpensive first bearing 26A and second bearing 26B can be used.

  In the bearing 26 according to the third embodiment, an outer ring-side spacer 26Pb is sandwiched between axially opposed surfaces of the outer ring 26Ab of the first bearing 26A and the outer ring 26Bb of the second bearing 26B. The outer race side spacer 26Pb is a cylindrical member surrounding the center of the shaft 12 (small diameter portion 12A). As shown in FIG. 26, the outer ring side spacer 26Pb can be made thicker than the axial thickness of the first bearing 26A and the second bearing 26B.

  In the bearing 26 according to the third embodiment, an inner ring side spacer 26Pa is sandwiched between axially opposed surfaces of the inner ring 26Aa of the first bearing 26A and the inner ring 26Ba of the second bearing 26B. The inner ring side spacer 26Pa is a cylindrical member that surrounds the center of the shaft 12 (small diameter portion 12A). The axial length of the inner race spacer 26Pa is smaller than the axial length of the outer race spacer 26Pb by 0.01 mm or more and 0.2 mm or less. As shown in FIG. 26, the inner ring side spacer 26Pa can be larger than the axial thickness of the first bearing 26A and the second bearing 26B.

  The shaft 12 has a small diameter portion 12A having a reduced diameter and a constant diameter, and has an abutment surface 12u due to a step at a boundary between the small diameter portion 12A and the large diameter portion. The inner ring 26Aa of the first bearing 26A is inserted into the abutting surface 12u so as to be in contact with the axial direction. The small diameter portion 12A is fitted with the inner ring 26Aa and the inner ring 26Ba, and is fixed by bonding or press fitting. Further, in the bearing 26 according to the third embodiment, the inner ring 26Ba of the second bearing 26B is pressed in the axial direction toward the abutting surface 12u in the direction P shown in FIG. 26, and the inner ring 26Aa exerts a reaction force from the abutting surface 12u. 26, in the PB direction. Thus, since the outer ring 26Ab and the outer ring 26Bb are constrained in the axial direction by the outer ring-side spacer 26Pb, the inner ring-side spacer 26Pa is plastically deformed to be compressed in the axial direction, and the first bearing 26A and the second bearing 26B Receives a preload, and is preloaded in the axial direction of the shaft 12. When the thickness of the inner ring side spacer 26Pa is smaller than the thickness of the outer ring side spacer 26Pb, the first bearing 26A and the second bearing 26B can easily maintain the preload. In the bearing 26 according to the third embodiment, the amount of preload can be controlled by the difference in thickness between the outer ring side spacer 26Pb and the inner ring side spacer 26Pa, and the management of the manufacturing process is facilitated.

  FIG. 27 is a cross-sectional view illustrating a bearing according to a modification of the third embodiment. The bearing 26 according to the modification of the third embodiment is different from the bearing 26 according to the third embodiment in that an inner ring-side spacer 26Pa is provided on an axially facing surface between the inner ring 26Aa of the first bearing 26A and the inner ring 26Ba of the second bearing 26B. Is not sandwiched. As a result, a gap 26N is generated between the inner ring 26Aa and the inner ring 26Ba. In the bearing 26 according to the modification of the third embodiment, the inner ring 26Ba of the second bearing 26B is axially pressed in the direction P shown in FIG. 27 toward the abutting surface 12u, and the inner ring 26Aa exerts a reaction force from the abutting surface 12u. It is received in the PB direction shown in FIG. Thus, since the outer race 26Ab and the outer race 26Bb are axially constrained by the outer race spacer 26Pb, the first bearing 26A and the second bearing 26B are preloaded so that the gap 26N is reduced, and the shaft 12 Preloaded in the direction.

(Fourth embodiment)
FIG. 28 is a perspective view illustrating a bearing according to the fourth embodiment. FIG. 29 is a cross-sectional view illustrating a bearing according to the fourth embodiment. The same members as those described above are denoted by the same reference numerals, and redundant description will be omitted.

  The bearing 26 according to the fourth embodiment includes a cover 26C in addition to the bearing described in the modification of the third embodiment. For this reason, in the bearing 26 according to the fourth embodiment, similarly to the bearing 26 according to the modification of the third embodiment, the inner ring 26Ba of the second bearing 26B faces the abutment surface 12u in the axial direction toward the P direction shown in FIG. The inner ring 26Aa receives a reaction force from the abutting surface 12u in the PB direction shown in FIG. Thus, since the outer race 26Ab and the outer race 26Bb are axially constrained by the outer race spacer 26Pb, the first bearing 26A and the second bearing 26B are preloaded so that the gap 26N is reduced, and the shaft 12 Preloaded in the direction.

  As the material of the cover 26C, iron such as carbon steel for machine structure, stainless steel, aluminum alloy, synthetic resin such as polycarbonate, or the like can be used. The outer ring 26Ab and the outer ring 26Bb of the bearing 26 according to the fourth embodiment are supported by a cover 26C. For this reason, the bearing 26 according to the fourth embodiment is inserted into the cover 21 shown in FIG. The cover 21 may be made of the same material as the cover 26C, but may be made of a material having a lower rigidity than the cover 26C. The cover 21 only needs to have a light-shielding property and can shield the optical scale 11 and the optical sensor unit 35 from light. When the inner circumference of the cover 26C and the outer circumferences of the outer ring 26Ab and the outer ring 26Bb are fixed with an adhesive, the bearing 26 according to the fourth embodiment has an increased bonding area, and the bonding between the first bearing 26A and the second bearing 26B. Strength is reinforced.

  As described above, the optical encoder unit 31 according to the fourth embodiment includes the cover 21, which is the first cylindrical body shown in FIG. 2, surrounding the optical sensor unit 35 and the optical scale 11, and the second cylindrical body shown in FIG. A cover 26C, which is a body, is provided, and the cover 26C is arranged on the inner periphery of the cover 21 and covers the outer ring side spacer. The cover 26C may be fixed to the inner periphery of the cover 21 of the first cylindrical body, or may be mounted on the sensor substrate 23 and positioned. Thereby, the positioning of the outer ring 26Ab and the outer ring 26Bb becomes simple, and the assemblability of the optical encoder unit 31 according to the fourth embodiment can be improved.

(Embodiment 5)
FIG. 30 is a configuration diagram of an optical encoder unit according to the fifth embodiment. FIG. 22 is an external perspective view of an optical encoder unit according to the fifth embodiment. As the bearing 26 of the optical encoder unit according to the fifth embodiment, the bearings 26 of the above-described first to fourth embodiments and their modifications can be used. The sensor substrate 23 according to the fifth embodiment is not covered by the cover 21, but fixes the cover 21 on the surface. In addition, the optical encoder unit 31 includes a connector CNT, which is an input / output terminal, fixed to the sensor substrate 23, and a preamplifier AMP, which is an amplifier. The conductor wiring 25 provided on the surface or inside of the sensor substrate 23 and the wiring 24 provided along the inside of the cover 21 are connected to the connector CNT, the preamplifier AMP, the optical sensor unit 35 and the light source 41 as appropriate. Connected.

(Embodiment 6)
FIG. 32 is an explanatory diagram illustrating an example of the arrangement of the optical scale and the optical sensor unit according to the sixth embodiment. FIG. 33 is a configuration diagram of an optical encoder unit according to the sixth embodiment. In the optical encoder unit 31 according to the sixth embodiment, the light source light 71 of the light source 41 is reflected on the optical scale 11, and the reflected light is used as the incident light 72 as the first light receiving portion PD1, the third light receiving portion PD3, and the second light receiving portion PD3. The optical sensor unit 35A having the light receiving unit PD2 and the fourth light receiving unit PD4 detects the light. The distance D between the emission surface of the light source 41 and the arrangement center S0 (optical sensor unit 35) is half that of the first embodiment described above as specular reflection. As shown in FIG. 33, the optical encoder unit 31 according to the sixth embodiment has an annular light shielding plate 27. Thereby, since the light shielding plate 17 can suppress unnecessary reflection, measurement accuracy can be improved.

  FIG. 34 is a configuration diagram of an optical encoder unit according to a modification of the sixth embodiment. The optical encoder unit 31 according to the modification of the sixth embodiment has the same arrangement of the reflection type optical scale and the optical sensor as the sixth embodiment. However, unlike the sixth embodiment, the sensor substrate 23 is covered with the cover 21. Instead, the cover 21 is fixed on the surface. In addition, the optical encoder unit 31 includes a connector CNT, which is an input / output terminal, fixed to the sensor substrate 23, and a preamplifier AMP, which is an amplifier.

  As described above, the optical encoder unit 31 includes the light source 41, the optical scale 11, the optical sensor unit 35 that detects the light source light from the light source 41 reflected on the optical scale 11, and the optical scale 11 attached thereto. And a first bearing 26A and a second bearing 26B of any one of the bearings 26 described in the first to fourth embodiments that rotatably support the shaft 12. The first bearing 26A and the second bearing 26B each include an inner ring, an outer ring, and a rolling element. The inner ring of the first bearing 26A and the inner ring of the second bearing 26B are preloaded in the axial direction of the shaft 12.

2 Optical encoder 3 Computing device 5 Control unit 10 Rotor 11 Optical scale 12 Shaft 20 Stator 21 Cover (first cylinder)
23 Sensor board (first board)
23FP Flexible boards 24, 24D, 25 Wiring 26 Bearing 26A First bearing 26Aa Inner ring 26Ab Outer ring 26B Second bearing 26Ba Inner ring 26Bb Outer ring 26C Cover (second cylindrical body)
26S, 26Pa, 26Pb Spacer 30 Unit base material 30b Surface 31 Optical encoder unit 35 Optical sensor units 39a, 39b Polarizing layer 41 Light source 41T Output surface 42 Light source substrate (second substrate)
71 Light source light 73 Incident light AMP Preamplifier AP Multiplier circuit CNT Connector D Distance Vc Differential signal Vs Differential signal

Claims (10)

Light source,
An optical scale having a signal track functioning as a polarizer;
An optical sensor unit that detects incident light transmitted or reflected by the optical scale from the light source light from the light source,
A shaft to which the optical scale is attached;
A first bearing that rotatably supports the shaft and has a first flange portion that protrudes radially in an annular shape on an outer ring;
A second bearing that rotatably supports the shaft and has a second flange portion on the outer ring that projects radially in an annular shape;
A cylindrical spacer fitted between the first flange portion and the second flange portion;
A first cylindrical body fixed between the first flange portion and the second flange portion by bonding or press-fitting and surrounding the optical sensor unit and the optical scale; Optical encoder unit.   The optical encoder unit according to claim 1, wherein a gap is provided between an inner ring of the first bearing and an inner ring of the second bearing.   The optical encoder unit according to claim 1, wherein an outer circumference of the spacer has the same diameter as a radial outer circumference of the first flange portion and the second flange portion. 4.   4. The optical encoder unit according to claim 1, wherein an axial thickness of the spacer is larger than an axial thickness of the first bearing and the second bearing. 5. The shaft has a small diameter portion having a constant diameter with a reduced diameter, and has a contact surface due to a step at a boundary between the small diameter portion and the large diameter portion,
The optical encoder unit according to any one of claims 1 to 4, wherein an inner ring of the first bearing is in contact with the abutting surface.   The optical encoder unit according to any one of claims 1 to 5, wherein the first cylinder has a light shielding property.   The optical encoder unit according to claim 1, further comprising a preamplifier on which the optical sensor unit is stacked, wherein the first cylinder surrounds the preamplifier. A sensor board on which the preamplifier and a connector that is an input terminal of the flexible board are mounted,
The optical encoder unit according to claim 7, wherein a side surface of the sensor substrate is covered with the first cylinder. An optical encoder unit according to any one of claims 1 to 8, and
An arithmetic unit for calculating a relative movement amount between the optical scale and the optical sensor unit from a light intensity detected by the optical sensor unit.   10. The method according to claim 9, wherein the calculating means stores in the storage device whether the rotational position of the optical scale is in a range of 0 ° or more and less than 180 ° or in a range of 180 ° or more and less than 360 °, and reads out the information at the time of startup. An optical encoder as described.

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