JP2019027871A - Rotation angle detection device - Google Patents

Abstract

To provide a rotation angle detection device 10 capable of accurately detecting a rotation angle.SOLUTION: A rotation angle detection device 10 comprises: a rotating body 30 having multiple reflection portions 70 disposed on a circumference of an identical radius from a center of rotation; a light emission part emitting light to the reflection portions 70; a light receiving part for receiving the light reflected by the reflection portions 70; and a control unit 60 configured to detect a rotation angle of the rotating body 30 on the basis of a received amount of the light by the light receiving part. Each reflection portion 70 is configured so that a dimension in a direction perpendicular to a circumferential direction continuously changes in the circumferential direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotation angle detection device.

  As conventional rotation angle detection devices, the rotation angle detection devices of Patent Documents 1 and 2 are known. The rotation angle detection device disclosed in Patent Document 1 includes a disk in which a plurality of through holes arranged at predetermined intervals in the circumferential direction are formed, and a light emitting element and a light receiving element that are disposed so as to sandwich the through holes of the disk. Including a sensor element. The output from the sensor element is switched between the H state and the L state in accordance with the amount of light transmitted through the through hole, and the rotation angle detecting device detects the rotation angle of the disk based on this state.

  In addition, the rotation angle detection device of Patent Document 2 is configured such that a light transmission type rotating disk is provided between the light emitter and the light receiver, and the transmittance of the amount of light transmitted through the disk changes along the circumference. ing. The rotation angle detection device detects the rotation angle of the disk in accordance with the change in the light amount.

JP-A-11-264725 JP-A-2-12016

  The resolution of the digital signal as in the rotation angle detection device of Patent Document 1 is limited to the interval between the through holes, and it has been difficult to achieve high resolution. In addition, the rotation angle detection device of Patent Document 2 is configured such that the transmittance of the light amount of the disk continuously changes over one round, and therefore, the change rate of the transmittance for each rotation angle is small, and the rotation The angle cannot be detected with high accuracy.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a rotation angle detection device capable of detecting a rotation angle with high accuracy.

  A rotation angle detection device according to an aspect of the present invention includes a rotating body provided with a plurality of reflecting units arranged on a circumference having the same radius from the rotation center, a light emitting unit that irradiates light to the reflecting unit, and a reflecting unit. A light receiving unit that receives the reflected light and a control unit that detects the rotation angle of the rotating body based on the amount of light received by the light receiving unit. The reflecting unit rotates in a direction perpendicular to the circumferential direction of the rotating body. It changes continuously along the circumferential direction of the body.

  According to this configuration, by providing the plurality of reflecting portions on the rotating body, it is possible to increase the rate of change in the amount of received light that is reflected by the reflecting portion and received by the light receiving portion. For this reason, the rotation angle of the rotating body based on the change in the amount of received light can be detected with high resolution.

  In the rotation angle detection device, the reflecting portion is a portion in which the dimension in the direction orthogonal to the circumferential direction of the rotating body continuously increases along the circumferential direction of the rotating body, and the dimension in the direction orthogonal to the circumferential direction of the rotating body. May have a portion that continuously decreases along the circumferential direction of the rotating body.

  According to this configuration, a change in the amount of received light that is reflected by the reflecting portion and received by the light receiving portion without increasing the size of the reflecting portion by dividing the reflecting portion into a portion that increases in size and a portion that decreases. This ratio can be further increased. For this reason, the resolution of the rotation angle of the rotating body based on the change in the amount of received light can be further improved.

  In the rotation angle detection device, the light emitting unit includes a first light emitting unit and a second light emitting unit, and the light receiving unit receives a light emitted from the first light emitting unit and reflected by the reflecting unit, and The second light receiving unit receives the light emitted from the second light emitting unit and reflected by the reflection unit, and the first light receiving unit and the second light receiving unit are spaced apart from each other in the circumferential direction of the rotating body. It may be arranged.

  According to this configuration, the received light amount by the first light receiving unit and the received light amount by the second light receiving unit can be used so that the received light amount by the light receiving unit changes monotonously. For this reason, the rotation angle of the rotating body based on the change in the amount of received light can be detected with high resolution.

  A rotation angle detection device according to another aspect of the present invention includes a rotating body provided with a plurality of transmission parts arranged on the circumference of the same radius from the rotation center, a light emitting part that irradiates light to the transmission part, and a transmission part A light receiving portion that receives light transmitted through the light receiving portion and a control portion that detects the rotation angle of the rotating body based on the amount of light received by the light receiving portion. The transmitting portion rotates in a direction perpendicular to the circumferential direction of the rotating body. It changes continuously along the circumferential direction of the body.

  According to this configuration, by providing the plurality of transmission parts on the rotating body, it is possible to increase the rate of change in the amount of received light that is transmitted through the transmission part and received by the light receiving part. For this reason, the rotation angle of the rotating body based on the change in the amount of received light can be detected with high resolution.

  In the rotation angle detection device, the transmission portion has a portion in which the dimension in the direction orthogonal to the circumferential direction of the rotating body continuously increases along the circumferential direction of the rotating body, and the dimension in the direction orthogonal to the circumferential direction of the rotating body. May have a portion that continuously decreases along the circumferential direction of the rotating body.

  According to the present invention, the transmission portion is divided into a portion where the size increases and a portion where the size decreases, so that a change in the amount of light received through the transmission portion and received by the light reception portion without increasing the size of the transmission portion. This ratio can be further increased. For this reason, the resolution of the rotation angle of the rotating body based on the change in the amount of received light can be further improved.

  In the rotation angle detection device, the light emitting unit includes a first light emitting unit and a second light emitting unit, and the light receiving unit receives a light emitted from the first light emitting unit and transmitted through the transmission unit, and A second light-receiving unit configured to receive the light emitted from the second light-emitting unit and transmitted through the transmission unit, and the first light-receiving unit and the second light-receiving unit are arranged at predetermined intervals in the circumferential direction of the rotating body; It may be.

  According to this configuration, the received light amount by the first light receiving unit and the received light amount by the second light receiving unit can be used so that the received light amount by the light receiving unit changes monotonously. For this reason, the rotation angle of the rotating body based on the change in the amount of received light can be detected with high resolution.

  In the rotation angle detection device, the control unit performs A / D conversion (Analog / Digital conversion) on the received light amount that continuously changes as the rotating body rotates, and detects the rotation angle of the rotating body according to the received light amount. May be. According to this configuration, since the rotation angle of the rotating body is detected based on the amount of received light in an analog format, this resolution can be improved.

  The rotation angle detection device further includes a low-speed rotation body that rotates at a lower speed than the rotation body in conjunction with the rotation body, and a rotation detection unit that detects a rotation angle of the low-speed rotation body, and the control unit detects rotation. The rotation angle of the rotating body may be detected from the number of rotations of the rotating body based on the detection signal from the unit and the amount of light received by the light receiving unit. According to this configuration, the absolute angle including a plurality of rotations of the rotator is calculated from the rotation number of the rotator based on the detection signal of the rotation detector and the rotation angle of the rotator based on the amount of light received by the light receiving unit. It can be detected with high accuracy.

  The present invention has an effect that the rotation angle can be detected with high accuracy in the rotation angle detection device.

  The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

It is a disassembled perspective view which shows the rotation angle detection apparatus which concerns on Embodiment 1 of this invention. It is the perspective view which looked at the rotary body of FIG. 1 from the 2nd main surface side. It is a figure which shows a part of rotary body of FIG. 2 roughly. It is a figure which shows the combination signal of the 1st light reception amount of the reflection part of FIG. 1, a 1st light reception part, the 2nd light reception amount of a 2nd light reception part, and a 1st light reception amount and a 2nd light reception amount. FIG. 5A is a diagram schematically showing a part of the reflecting portion of the rotation angle detection device according to the fourth modification of the first embodiment of the present invention. FIG.5 (b) is a figure which shows schematically a part of reflection part of the rotation angle detection apparatus which concerns on the modification 1 of Embodiment 1 of this invention. It is the figure which looked at the rotation angle detection apparatus which concerns on Embodiment 2 of this invention from the 1st main surface side of the rotary body. It is the figure which looked at the rotation angle detection apparatus of FIG. 6 from the side.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout all the drawings, and redundant description thereof is omitted.

(Embodiment 1)
<Configuration of rotation angle detection device>
As shown in FIG. 1, the rotation angle detection device 10 according to Embodiment 1 is mounted on a detection object such as a steering shaft of a vehicle (not shown) and detects the rotation angle of the detection object. Is. The rotation angle detection device 10 includes a rotating body 30, a light emitting unit 40, a light receiving unit 50, and a control unit 60, which are accommodated in the case 20 in the present embodiment.

  The case 20 includes, for example, a box-shaped main body 21 that opens to the front, and a lid 22 that covers the opening of the main body 21, and has an internal space 23. The case 20 accommodates the rotating body 30, the light emitting unit 40, the light receiving unit 50, and the control unit 60 in the internal space 23. Further, the case 20 is provided with a through hole 24 through which an object to be detected penetrates the main body portion 21 and the lid portion 22.

  The rotating body 30 has an annular shape having an opening 34 into which the detected part is inserted, and is provided on the inner surface so that a locking part 31 locked to the detected object protrudes inward. It has been. The rotating body 30 is arranged in the case 20 so as to be coaxial with the above-described through hole 24 so that the first main surface faces the main body portion 21 and the second main surface faces the lid portion 22. A plurality of reflecting portions 70 forming a reflecting surface are provided on the outer peripheral edge of the rotating body 30.

  In the following, in the direction along the axis of the through hole 24 of the case 20, the main body 21 side is defined as the lower side and the lid 22 side is defined as the upper side. Therefore, the lower surface of the rotating body 30 forms the first main surface described above, and the upper surface of the rotating body 30 forms the second main surface described above. Such a definition of “vertical direction” does not limit the vertical direction of the rotation angle detection device 10.

  The plurality of reflecting portions 70 are arranged in the circumferential direction of the rotating body 30 (hereinafter referred to as “circumferential direction”) with the reflecting surface thereof facing downward, and are arranged on the first main surface side below the rotating body 30. Has been. The reflection unit 70 is formed of a material that reflects light, for example, a metal or a plated resin. Details of the reflection unit 70 will be described later.

  The light emitting unit 40 is a light source that emits light such as an LED, and includes a first light emitting unit 41 and a second light emitting unit 42. For example, the first light emitting unit 41 and the second light emitting unit 42 are arranged so as to irradiate light upward so as to face the reflecting unit 70 so that the reflecting unit 70 is irradiated with light. The 1st light emission part 41 and the 2nd light emission part 42 are arrange | positioned at predetermined intervals mutually.

  The light receiving unit 50 is an element that receives the light reflected by the reflection unit 70, and includes a first light receiving unit 51 and a second light receiving unit 52. For example, the first light receiving unit 51 is disposed to face the reflecting unit 70 so as to receive the light emitted from the first light emitting unit 41 and reflected by the reflecting unit 70. For example, the second light receiving unit 52 is disposed to face the reflecting unit 70 so as to receive the light emitted from the second light emitting unit 42 and reflected by the reflecting unit 70.

  The first light receiving unit 51 and the second light receiving unit 52 are arranged at a predetermined interval from each other, and the interval s is, for example, relative to the dimension W that is the total length in the circumferential direction of one reflecting unit 70. It is set so that s = (n−1 / 2) W. Here, n is a natural number. The first light receiving unit 51 and the second light receiving unit 52 output a signal corresponding to the amount of received light to the control unit 60.

  The first light emitting unit 41 and the first light receiving unit 51, and the second light emitting unit 42 and the second light receiving unit 52 are, for example, optical sensors such as a reflective photo interrupter provided integrally. Also good. These are mounted on the substrate 61 together with the control unit 60, for example.

  The control unit 60 detects the rotation angle of the rotating body 30 based on the amount of light received by the light receiving unit 50. The control unit 60 includes a calculation unit (not shown) such as a CPU and a storage unit (not shown) such as a ROM and a RAM. The storage unit stores a program necessary for the function of the rotation angle detection device 10 and various data referred to when the program is executed. The calculation unit reads this program from the storage unit and executes it, so that the control unit 60 controls the operation of each unit. The control unit 60 may be configured by a single control device that performs centralized control, or may be configured by a plurality of control devices that perform distributed control in cooperation with each other.

<Structure of the reflection part>
As shown in FIG.2 and FIG.3, the reflection part 70 is a rhombus shape, for example, Comprising: It connects with the rotary body 30 by the connection part 33a and the annular ring part 33b. The reflective portion 70 is arranged so that one of the pair of diagonal lines (first diagonal line 71) is in a direction perpendicular to the circumferential direction (in this embodiment, the radial direction of the rotating body 30). . The connecting portion 33 a extends along the first diagonal line 71.

  One arbitrary reflection part 70 has one end (first end 72) in the circumferential direction connected to the other end (second end 73) of another adjacent reflection part 70. Accordingly, the plurality of reflecting portions 70 are arranged side by side continuously on the circumference having the same radius from the rotation center 30 </ b> A of the rotating body 30. The first end 72 and the second end 73 are located at positions where the first diagonal line 71 is sandwiched between them, and are arranged line-symmetrically with respect to the first diagonal line 71, for example.

  The reflection unit 70 has, for example, a shape in which the first diagonal line 71 is shorter than the other diagonal line (second diagonal line 74) that forms a pair with the first diagonal line 71. The reflecting portion 70 includes two sides outside the second diagonal 74 (first outer edge 75 and second outer edge 76) and two sides inside the second diagonal 74 (first inner edge 77 and second edge 74). It has an inner edge 78). These sides have an inclination such that the distance from the rotation center 30A continuously changes in the circumferential direction. For example, the sides are formed in a straight line having a constant inclination.

  The “inclination” of each side 75 to 78 here means an inclination with respect to the circumference of the same radius from the rotation center 30 </ b> A of the rotating body 30, and generally means an inclination with respect to the second diagonal line 74.

  The first outer edge 75 and the first inner edge 77 are located at a position where the second diagonal line 74 is sandwiched between them, and are arranged symmetrically with respect to the second diagonal line 74, for example. Similarly, the second outer edge side 76 and the second inner edge side 78 are in positions where the second diagonal line 74 is sandwiched between each other, and are arranged symmetrically with respect to the second diagonal line 74, for example.

  The reflection unit 70 includes a first portion 70a and a second portion 70b. The first portion 70a is a portion in which the dimension in the direction orthogonal to the circumferential direction (that is, the tangential direction of the annular rotator 30) continuously increases as the size approaches the second portion 70b along the circumferential direction. . The second portion 70b is a portion in which the dimension in the direction orthogonal to the circumferential direction continuously decreases as the distance from the first portion 70a increases along the circumferential direction.

  The first portion 70 a is, for example, a range closer to the first end 72 than the first diagonal line 71 and a range between the first outer edge 75 and the first inner edge 77. In this range, the first outer edge 75 and the first inner edge 77 are continuously inclined so as to be separated from each other from the first end 72 side toward the first diagonal line 71 side. Therefore, for example, when the reflecting unit 70 rotates in the direction of the thick arrow in FIG. 3, the direction orthogonal to the circumferential direction (here, the radial direction of the rotating body 30) when viewed from the light emitting unit 40 (FIG. 1). Hereinafter, the distance between the first outer edge 75 and the first inner edge 77 (the dimension of the first portion 70a in the radial direction) in the “radial direction”) continuously increases along the circumferential direction. To do.

  Here, since each of the first outer edge 75 and the first inner edge 77 is a straight line, the dimension of the first portion 70a in the radial direction increases linearly along the circumferential direction. That is, when the reflecting portion 70 is displaced (rotated) in the circumferential direction, in the first portion 70a, the displacement amount in the circumferential direction is proportional to the displacement amount in the radial direction viewed at a fixed point with a positive proportionality constant.

  The second portion 70 b is, for example, a range closer to the second end 73 than the first diagonal line 71 and a range between the second outer edge 76 and the second inner edge 78. In this range, the second outer edge 76 and the second inner edge 78 are continuously inclined so as to approach each other from the first diagonal line 71 side toward the second end 73 side. For this reason, for example, when the reflecting unit 70 rotates in the direction of the thick arrow in FIG. 3, when viewed from the light emitting unit 40 (FIG. 1), the second in the direction orthogonal to the circumferential direction (here, the radial direction). The distance between the outer edge 76 and the second inner edge 78 (the dimension of the second portion 70b in the radial direction) decreases continuously along the circumferential direction.

  Here, since each of the second outer edge side 76 and the second inner edge side 78 is a straight line, the dimension of the second portion 70b in the radial direction decreases linearly along the circumferential direction. That is, when the reflecting portion 70 is displaced (rotated) in the circumferential direction, in the second portion 70b, the displacement amount in the circumferential direction is proportional to the displacement amount in the radial direction viewed at a fixed point with a negative proportional constant.

  The diameter of the irradiation light from the first light emitting unit 41 (FIG. 1) in the reflection unit 70 is larger than the minimum radial dimension of the reflection unit 70 (in this embodiment, the radial dimension of the ends 72 and 73). The first light emitting unit 41 is disposed with respect to the reflecting unit 70 so as to be slightly smaller than the maximum dimension in the radial direction of the reflecting unit 70.

  As a result, as the rotating body 30 rotates in one direction, the amount of light reflected by the reflecting portion 70 from the first light emitting portion 41 continuously increases while the first portion 70a is reflected. , While the second portion 70b is reflected, it decreases continuously. In addition, as the rotating body 30 rotates in another direction opposite to one direction, the amount of light reflected by the reflecting unit 70 from the first light emitting unit 41 is reflected by the second portion 70b. It increases continuously and decreases continuously while the first portion 70a is reflected. Therefore, the amount of light received by the first light receiving unit 51 (FIG. 1) that receives the reflected light continuously increases and decreases as the rotating body 30 rotates. The second light emitting unit 42 is the same as the first light emitting unit 41.

<Detection method of rotation angle detection device>
FIG. 4 shows the developed shape of the reflection unit 70, the amount of light received by the first light receiving unit 51 (first light receiving amount 51a), the amount of light received by the second light receiving unit 52 (second light receiving amount 52a), and the first light receiving amount 51a. A combination with the second received light amount 52a is shown.

  In this case, when the reflecting portion 70 has a dimension W that is the entire length in the circumferential direction (a dimension between the first end 72 and the second end 73 of the reflecting portion 70) expressed as an angle centered on the rotation center 30A, for example, It is formed to be 5 degrees. Further, the interval between the first light receiving unit 51 and the second light receiving unit 52 is arranged at a position where the interval s is 2.5 degrees apart in the circumferential direction, for example.

  For example, when the irradiation light from the first light emitting unit 41 irradiates the vicinity of the first end 72 of the reflection unit 70, the first portion 70 a in the radial direction with respect to the dimension of the irradiation light in the first portion 70 a of the reflection unit 70. The dimensions of are small. For this reason, much light of the irradiation light is not reflected by the reflection unit 70, but passes through the upper side of the first outer edge 75 and the lower side of the first outer edge 75 of the reflection unit 70. Thereby, the amount of light reflected by this portion and received by the first light receiving unit 51 is small, and the first received light amount 51a of the point a indicating this light amount becomes small.

  On the other hand, when the rotating body 30 rotates in the direction indicated by the arrow in FIG. 3, the position of the irradiation light of the first light emitting unit 41 in the first portion 70 a is first from the first end 72 side according to the rotation angle. Move to the diagonal 71 side. For this reason, the dimension of the first portion 70a in the radial direction increases, and the amount of light reflected by this portion and received by the first light receiving portion 51 increases. At this time, when the dimension of the first portion 70a in the radial direction increases linearly in the circumferential direction, the first received light amount 51a at the points a to b indicating the light amount of the first light receiving unit 51 also increases linearly. To go.

  Thereafter, for example, the irradiation light of the first light emitting unit 41 is reflected by the connecting portion 33a, or the size of the radial reflection portion 70 is larger than the size of the irradiation light in the reflection portion 70. Then, all the irradiation light is reflected by the reflection unit 70 and the like. Thereby, the amount of light received by the first light receiving unit 51 that receives the reflected light is constant, and the first amount of light received 51a from point b to point c to point d is constant.

  Furthermore, when the rotating body 30 rotates, the light from the first light emitting unit 41 is irradiated to the second portion 70b. And the position of the irradiation light of the 1st light emission part 41 in the 2nd part 70b moves to the 2nd end 73 side from the 1st diagonal 71 side with rotation of the rotary body 30. FIG. For this reason, the dimension of the second portion 70b in the radial direction decreases, and the amount of light reflected by this portion and received by the first light receiving portion 51 decreases. At this time, when the dimension of the second portion 70b in the radial direction decreases linearly in the circumferential direction, the first received light amount 51a at the points d to e indicating the light amount of the first light receiving unit 51 also decreases linearly. To go.

  As described above, the first light receiving amount 51a of the first light receiving unit 51 increases linearly with respect to one reflecting unit 70, and thereafter becomes constant and decreases linearly. With this as one cycle, the first received light amount 51a repeatedly increases and decreases as the rotating body 30 rotates. Similarly to the first received light amount 51a of the first light receiving unit 51, the second received light amount 52a of the second light receiving unit 52 also increases linearly for each reflecting unit 70, and then becomes constant and linear. Decrease. And since the 1st light-receiving part 51 and the 2nd light-receiving part 52 are arrange | positioned apart as above-mentioned, while the light-receiving amount of one is constant, the light-receiving amount of the other increases or decreases. (For example, see the first received light amount 51a and the second received light amount 52a in the section from point b to point c to point d in FIG. 4).

  The first received light amount 51 a of the first light receiving unit 51 and the second received light amount 52 a of the second light receiving unit 52 are input to the control unit 60. For example, the control unit 60 A / D converts these received light amounts, and detects the rotation angle of the rotating body 30 according to the received light amount. In addition, the control unit 60 determines the first received light amount 51a, the second received light amount 52a, and a predetermined threshold value in order to determine which value to use between the first received light amount 51a and the second received light amount 52a. Compare. This threshold value is a value equal to or less than a value when each of the first received light amount 51a and the second received light amount 52a becomes constant, and is predetermined. In the present embodiment, the threshold value is a value when the first received light amount 51a is constant (the same value as when the second received light amount 52a is constant).

  In the case of FIG. 4, the second received light amount 52a reaches the threshold value in the section from point a to point b. For this reason, the control part 60 detects the rotation angle of the rotary body 30 based on the 1st light reception amount 51a in this area. The relationship between the first received light amount 51a and the rotation angle of the rotating body 30 is determined in advance, and the rotation angle corresponding to the first received light amount 51a is acquired by the A / D conversion described above. Note that, when the rotating body 30 is rotated, the first received light amount 51a continuously changes, so the rotation angle corresponding to the first received light amount 51a also changes continuously.

  When the first received light amount 51a reaches the threshold value at the point b, the control unit 60 switches the value to be adopted from the first received light amount 51a to the second received light amount 52a. That is, in the section from point b to point d, the rotation angle of the rotating body 30 is acquired based on the second received light amount 52a. The relationship between the second received light amount 52a and the rotation angle of the rotating body 30 is predetermined.

  Then, when the second received light amount 52a reaches the threshold value at the point d, the control unit 60 switches the value to be adopted from the second received light amount 52a to the first received light amount 51a. In other words, the rotation angle of the rotator 30 is detected based on the first received light amount 51a in the section from the point d until the next adopted value is switched.

  Thus, whenever each value of the 1st light reception amount 51a and the 2nd light reception amount 52a reaches a threshold value, the control part 60 switches between the 1st light reception amount 51a and the 2nd light reception amount 52a, and according to each light reception amount The rotation angle of the rotating body 30 is detected. For example, when the rotating body 30 rotates from point a to point e, the control unit 60 detects that this rotation angle is 5 degrees.

  As described above, in the reflecting portion 70, the dimension in the direction orthogonal to the circumferential direction continuously changes along the circumferential direction. Along with this, when the rotating body 30 rotates in one direction, the amount of light reflected by the reflecting unit 70 and received by the light receiving unit 50 continuously changes. For this reason, the rotation angle of the rotating body 30 can be detected according to the amount of received light.

  Further, the rotating body 30 is provided with a plurality of reflecting portions 70, and the amount of received light continuously changes for each reflecting portion 70. For this reason, the rate of change in the amount of received light in the circumferential direction can be increased in accordance with the number of reflecting portions 70, and the rotation angle obtained based on the amount of received light can be detected with high accuracy.

  In addition, the reflective portion 70 has a first portion 70a in which the dimension in the direction orthogonal to the circumferential direction continuously increases along the circumferential direction, and the dimension in the direction orthogonal to the circumferential direction continuously along the circumferential direction. It has the 2nd part 70b to reduce. As a result, two continuously changing ranges are provided in one reflecting portion 70. For this reason, the rate of change in the amount of received light in the circumferential direction can be increased without increasing the size of the reflecting portion 70, and the rotation angle of the rotating body 30 obtained based on the amount of received light can be further improved in accuracy. Figured.

  Moreover, since the reflecting portion 70 has a rhombus shape, the amount of light received by the light receiving portion 50 reflected by the reflecting portion 70 changes linearly with the rotation of the rotating body 30. As a result, the rotation angle can be detected more easily according to the amount of received light.

  Further, the two light receiving units (the first light receiving unit 51 and the second light receiving unit 52) arranged at intervals are received by the reflected light from the reflecting unit 70, and these received light amounts are combined and used for angle detection. ing. Thereby, in the central part (near the first diagonal line 71) in the circumferential direction of the reflecting part 70, such as the light receiving quantity of one light receiving part does not continuously change, the light receiving quantity of the other light receiving part is used. it can. For this reason, since the amount of light received from the light receiving unit 50 can be continuously changed, the accuracy of the rotation angle obtained based on the amount of received light can be further improved.

(Modification 1)
In the above configuration, the reflecting portion 70 has a rhombus shape. However, if the dimension of the reflecting portion 70 in the direction orthogonal to the circumferential direction changes continuously along the circumferential direction, the shape of the reflecting portion 70 is It is not limited. For example, as shown in FIG. 5A, the reflecting portion 170 may be triangular. In this case, the reflecting portion 170 is arranged such that one of the three sides (first side 170a) extends in the radial direction. The remaining two sides (second side 170b and third side 170c) are arranged so as to be line-symmetric with respect to a line orthogonal to the first side 170a.

  Thereby, the dimension of the reflecting portion 170 in the direction orthogonal to the circumferential direction (in this case, the radial direction) is the distance between the second side 170b and the third side 170c of the rotating body 30 in the radial direction. The dimension of the radial reflecting portion 170 changes linearly in the circumferential direction.

(Modification 2)
In the above configuration, the sides of the reflecting portion 70 have an inclination that continuously changes in the circumferential direction, and this inclination is formed in a constant linear shape. However, the side of the reflection unit 70 is not limited to this as long as it continuously changes in the circumferential direction. For example, the side of the reflection unit 70 may be a curve whose inclination continuously changes in the circumferential direction.

(Modification 3)
In the above configuration, the reflecting portion 70 is disposed on the first main surface of the rotating body 30, but the position of the reflecting portion 70 is not limited to this. For example, the reflection unit 70 may be provided on a side surface connecting the first main surface and the second main surface of the rotating body 30. In this case, the direction orthogonal to the circumferential direction is the axial direction of the rotating body 30 that is also orthogonal to the radial direction. The dimension of the reflecting portion 70 in the axial direction changes continuously along the circumferential direction.

(Modification 4)
In the above configuration, the reflecting part 70 is provided on the rotating body 30. However, as shown in FIG. 5B, a transmitting part 270 may be provided on the rotating body 30 instead of the reflecting part 70. In this case, for example, an opening such as a notch that transmits light is provided as a transmitting portion 270 on the outer peripheral edge of the rotating body 30. A plurality of transmission parts 270 are provided side by side on the circumference of the same radius from the rotation center 30 </ b> A of the rotating body 30. The transmission part 270 is formed in a shape such that a dimension in a direction orthogonal to the circumferential direction such as a triangular shape and a rhombus shape continuously changes along the circumferential direction.

  For example, the transmission part 270 has a rhombus shape, and a dimension 270a in which the dimension perpendicular to the circumferential direction continuously increases along the circumferential direction, and a dimension perpendicular to the circumferential direction along the circumferential direction. And has a continuously decreasing portion 270b.

  The first light receiving unit 51 is disposed so as to sandwich the transmission unit 270 with the first light emission unit 41 so as to receive the light emitted from the first light emission unit 41 and passed through the transmission unit 270. The second light receiving unit 52 is disposed so as to sandwich the transmission unit 270 with the second light emission unit 42 so as to receive the light emitted from the second light emission unit 42 and passed through the transmission unit 270. The first light-receiving unit 51 and the second light-receiving unit 52 are spaced apart from each other in the circumferential direction. For example, this interval is (n−1) with respect to the dimension W that is the total length in the circumferential direction of the reflecting unit 70. / 2) Set to W. This n is a natural number.

  For example, the first light-emitting unit 41 and the first light-receiving unit 51, and the second light-emitting unit 42 and the second light-receiving unit 52 may be optical sensors such as a transmission type photo interrupter provided integrally. .

(Embodiment 2)
The rotation angle detection apparatus 10 according to the second embodiment further includes a speed reduction mechanism 80, a low speed rotator 83, and a rotation detection unit 90, as shown in FIGS. In this case, the rotator 30 is a main gear provided with a plurality of teeth 32 on the first main surface. The plurality of teeth 32 are arranged side by side continuously on the circumference of the same radius from the rotation center 30 </ b> A of the rotating body 30. Here, the radius of the circumference where the teeth 32 are arranged is smaller than the radius of the circumference where the reflecting portions 70 are arranged, and the teeth 32 are arranged closer to the center of the rotating body 30 than the reflecting portions 70.

  The speed reduction mechanism 80 is a mechanism that reduces the rotational speed of the rotating body 30 and rotates the low-speed rotating body 83 at a lower speed than the rotating body 30 in conjunction with the rotating body 30. The speed reduction mechanism 80 has two gears (a first low speed gear 81 and a second low speed gear 82), and these gears are arranged on the first main surface side of the rotating body 30.

  The first low-speed gear 81 is a spur gear whose teeth mesh with the teeth 32 of the rotating body 30 and is arranged so that the rotation shaft extends in the radial direction. The second low speed gear 82 is, for example, a worm provided with a slanted tooth like a screw, and is provided on the rotating shaft of the first low speed gear 81.

  The low-speed rotating body 83 is a worm wheel whose teeth mesh with the inclined teeth of the second low-speed gear 82, and is arranged so that the rotating shaft is parallel to the rotating shaft of the rotating body 30. The reduction ratio between the rotating body 30 and the low speed rotating body 83 is set so that, for example, the rotating body 30 rotates 5 times while the low speed rotating body 83 rotates 1 time. Thus, since the reduction ratio can be set large by using the worm for the speed reduction mechanism 80, the speed reduction mechanism 80 and the low-speed rotating body 83 can be downsized, and further downsizing of the rotation angle detecting device 10 can be achieved. Figured.

  The rotation detection unit 90 is a sensor that detects the rotation angle of the low-speed rotator 83 and is, for example, a magnetic sensor having a magnet 91 and a magnetic detection element 92. The rotation detection unit 90 is not limited to a magnetic sensor, and an optical sensor, a sliding sensor, or the like can be used.

  The magnet 91 is provided on the low speed rotator 83 and rotates together with the low speed rotator 83. The magnetic detection element 92 is provided on the lower surface of the substrate 61 so as to face the magnet 91 of the low-speed rotating body 83 at a predetermined interval, detects the magnetic field strength of the magnet 91, and sends a detection signal to the control unit 60. Output. The strength of this magnetic field changes according to the rotation of the low-speed rotating body 83.

  The control unit 60 obtains the rotation angle of the low speed rotator 83 based on the change in the strength of the magnetic field detected by the magnetic detection element 92, and obtains the rotation speed of the rotator 30 from this rotation angle. The relationship between the strength of the magnetic field and the rotation angle of the low speed rotator 83 is predetermined. Further, the relationship between the rotation angle of the low-speed rotator 83 and the rotational speed of the rotator 30 is determined in advance by a reduction ratio or the like.

  The control unit 60 rotates from the number of rotations of the rotating body 30 based on the detection signal of the magnetic detection element 92 and the rotation angle of the rotating body 30 based on signals from the first light receiving unit 51 and the second light receiving unit 52. The absolute angle of the body 30 is detected. For example, when the rotating body 30 is set to rotate 5 times while the low-speed rotating body 83 is set to rotate once, the rotation angle in the range of the absolute angle of the rotating body 1800 degrees can be detected. Since the rotation angle of the rotating body 30 is detected with high resolution as described above, an absolute angle including a plurality of rotations of the rotating body 30 based on the rotation angle can be detected with high accuracy.

(Other embodiments)
In all the embodiments described above, the light emitting unit 40 is configured by the first light emitting unit 41 and the second light emitting unit 42. However, the number of the light emission parts 40 is not limited to this, Three or more may be provided. In this case, the light receiving units 50 may also be configured by the number of light receiving units 50 equal to the number of the light emitting units 40.

  In all the embodiments described above, the interval s is set to be s = (n−1 / 2) W, but is not limited to this value. For example, the amount of light received by each of the first light receiving unit 51 and the second light receiving unit 52 periodically increases and decreases as the rotating body 30 rotates, but the amount of received light is constant between the increase and decrease. Can be included (see FIG. 4). In such a case, the first light receiving unit 51 and the second light receiving unit 52 set the interval s so that the amount of received light that is increased or decreased by at least one of the light receiving units 50 can always be detected while the rotating body 30 is rotating. You only have to set it.

  In all the embodiments described above, the interval in which one of the first received light amount 51a and the second received light amount 52a is constant is equal to the interval in which the other received light amount is increased or decreased. Yes. When the currently received light amount reaches the threshold value, the other received light amount is switched instead. However, it is not limited to this case.

  For example, a section in which one of the first received light quantity 51a and the second received light quantity 52a is constant may be narrower than a section in which the other received light quantity is increasing or decreasing. In this case, it is good also as employ | adopting the light reception amount which has not reached the threshold value among each light reception amount. And it is preferable to set the shape of the reflection part 70 and / or the connection part 33a, the shape of the irradiation light of the light emission part 40, etc. so that it may become the relationship of such light reception amount.

  Note that all the above embodiments may be combined with each other as long as they do not exclude each other. For example, the first modification of the first embodiment may be applied to the second to fourth modifications of the first embodiment. Further, the second modification of the first embodiment may be applied to the third and fourth modifications of the first embodiment. The third modification of the first embodiment may be applied to the fourth modification of the first embodiment. Furthermore, each of the rotation angle detection devices 10 of the first to fourth modifications of the first embodiment may further include the low-speed rotator and the rotation detection unit 90 of the second embodiment.

  The above description should be construed as illustrative only and the present invention is provided for the purpose of teaching those skilled in the art the best mode of carrying out. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The rotation angle detection device of the present invention is useful as a rotation angle detection device that can detect the rotation angle with high accuracy.

DESCRIPTION OF SYMBOLS 10: Rotation angle detection apparatus 30: Rotating body 31: Locking part 40: Light emission part 50: Light receiving part 60: Control part 70: Reflection part 83: Low-speed rotator 90: Rotation detection part 170: Reflection part 270: Transmission part

Claims (8)

A rotating body provided with a plurality of reflecting portions arranged on the circumference of the same radius from the center of rotation;
A light emitting unit for irradiating the reflective unit with light;
A light receiving portion for receiving the light reflected by the reflection portion;
A control unit that detects a rotation angle of the rotating body based on an amount of light received by the light receiving unit;
The said reflection part is a rotation angle detection apparatus with which the dimension of the direction orthogonal to the circumferential direction of the said rotary body changes continuously along the circumferential direction of the said rotary body.   The reflective portion includes a portion in which a dimension in a direction orthogonal to the circumferential direction of the rotating body continuously increases along the circumferential direction of the rotating body, and a dimension in a direction orthogonal to the circumferential direction of the rotating body. The rotation angle detection device according to claim 1, further comprising a portion that continuously decreases along a circumferential direction of the rotating body. The light emitting unit includes a first light emitting unit and a second light emitting unit,
The light receiving unit receives the light emitted from the first light emitting unit and reflected by the reflecting unit, and receives the light emitted from the second light emitting unit and reflected by the reflecting unit. Having a second light receiving portion;
3. The rotation angle detection device according to claim 1, wherein the first light receiving unit and the second light receiving unit are arranged at a predetermined interval in the circumferential direction of the rotating body. A rotating body provided with a plurality of transmission parts arranged on the circumference of the same radius from the center of rotation;
A light emitting unit that emits light to the transmission unit;
A light receiving unit that receives light transmitted through the transmission unit;
A control unit that detects a rotation angle of the rotating body based on an amount of light received by the light receiving unit;
The transmission part is a rotation angle detection device in which a dimension in a direction orthogonal to a circumferential direction of the rotating body continuously changes along the circumferential direction of the rotating body.   The transmission portion includes a portion in which a dimension in a direction orthogonal to the circumferential direction of the rotating body continuously increases along the circumferential direction of the rotating body, and a dimension in a direction orthogonal to the circumferential direction of the rotating body. The rotation angle detection device according to claim 4, comprising a portion that continuously decreases along the circumferential direction of the rotating body. The light emitting unit includes a first light emitting unit and a second light emitting unit,
The light receiving unit receives a light irradiated from the first light emitting unit and transmitted through the transmitting unit, and a second light receiving a light irradiated from the second light emitting unit and transmitted through the transmitting unit. Having a light receiver,
The rotation angle detection device according to claim 4 or 5, wherein the first light receiving unit and the second light receiving unit are arranged at a predetermined interval in the circumferential direction of the rotating body.   The said control part A / D-converts the said light reception amount which changes continuously with rotation of the said rotary body, and detects the rotation angle of the said rotary body according to the said light reception amount. The rotation angle detection apparatus as described in any one of Claims. A low-speed rotating body that rotates at a lower speed than the rotating body in conjunction with the rotating body;
A rotation detector that detects a rotation angle of the low-speed rotating body;
The said control part is comprised so that the rotation angle of the said rotary body may be detected from the rotation speed of the said rotary body based on the detection signal by the said rotation detection part, and the light-receiving amount in the said light-receiving part. The rotation angle detection apparatus as described in any one of 1-7.

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