Encoder detection unit and encoder device

Abstract

The present invention provides an encoder detection unit that optically detects the movement of a moving part having an identifier at predetermined intervals, and reduces the distortion component of the received light signal without reducing the amount of received light. [Solution] The moving unit 120 is provided with a plurality of identifiers 130 that transmit or reflect irradiated light at predetermined intervals, and the encoder detection unit 140 comprises a light-emitting unit 141 that irradiates the identifiers 130 with light, and a light-receiving unit 142 that receives light L transmitted or reflected from the identifiers 130 and generates a light-receiving signal, and the light-receiving region 1420 of the light-receiving unit 1420 has an incidence start end 1421 in which the light-receiving area increases in a first direction and a second direction when light L transmitted or reflected from the identifiers 130 starts to enter the light-receiving region 1420 as the moving unit 120 moves, and an incidence end end 1422 in which the light-receiving area decreases in a first direction and a second direction when light L transmitted or reflected from the identifiers 130 ends to enter the light-receiving region 1420 as the moving unit 120 moves.

Description

Technical Field

[0004] , , , , , ,

[0001] This invention relates to an encoder detection unit and an encoder device, and more particularly to an encoder detection unit and an encoder device that optically detect the movement of a moving part.

Background Art

[0002] There are encoder devices that optically detect the rotational movement or linear movement of a moving part provided with a plurality of identifiers at predetermined intervals. As such an encoder device, for example, there is one in which a light transmission part or a light reflection part is provided as an identifier on a rotating plate as a moving part. In this encoder device, the rotation angle of the rotating plate is detected by the light transmitted through the light transmission part or the light reflected by the light reflection part. In addition to the rotating plate as a moving part, there are also those that detect the linear movement amount of a rod-shaped moving part. This type of encoder is proposed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this encoder device, the shape of the transmitted light from the light transmission part or the reflected light from the light reflection part and the shape of the light receiving area of the light receiving part are generally configured in a rectangular shape. Here, referring to FIG. 18, the movement of the transmitted light or reflected light (hereinafter simply referred to as "light") accompanying the movement of the moving part and the state of light reception of the light receiving area will be described. FIG. 18 is an explanatory diagram showing the change in the shape and light receiving area of the light receiving area of a conventional encoder detection unit. In FIGS. 18(a) to (h), the rectangular light receiving area uses four areas a, b, a', b' as basic units with a phase of 0° to 360°. Note that the light receiving area shows a total of two basic units. Figures 18(a) to (e) show how light L0 and light L1 move from left to right on the paper, occupying 180° of the 360° phase range, moving in 45° increments from 0° to 180°. Figures 18(f) to (h) show how light L0, L1, and light L2 move from left to right on the paper, occupying 180° of the 360° phase range, moving in 45° increments from 225° to 315°.

[0005] Figure 19 shows the waveform of the received light signal obtained in region a, which receives any of the light sources L0, L1, or L2 shown in Figure 18. Figure 19 is an explanatory diagram showing the waveform of the received light signal according to the shape of the light-receiving region of a conventional encoder detection unit. That is, the waveform of the received light signal obtained in region a, which receives any of the light sources L0, L1, or L2 shown in Figure 18, is a repeating trapezoidal waveform in which the amplitude changes trapezoidally according to the phase, as shown in Figure 19. Note that the slope is y=-ax from 0° to 90°, it is flat with y=0 from 90° to 180°, the slope is y=ax from 180° to 270°, and it is flat with y=constant maximum value from 270° to 360°. A trapezoidal waveform in a received light signal contains high-order harmonic components as distortion components, compared to an ideal sinusoidal or cosine waveform. Figure 20 shows the distortion components of a conventional trapezoidal waveform. Figure 20 is a characteristic diagram showing the intensity distribution of harmonic components contained in the received light signal according to the shape of the light-receiving area of ​​a conventional encoder detection unit. Figure 20 shows the distribution of harmonic components of the second order and above, with the original detected component set as the first order. FFT analysis of experimental results under certain conditions revealed that, with the energy of the first-order component set at 100%, the energy of the second to sixteenth-order harmonic components accounted for 21%. These harmonic components are the cause of errors when calculating the rotation angle from the received signal.

[0006] Furthermore, in order to cancel out the harmonic components contained in the received light signal, there have been attempts to make the trapezoidal waveform closer to a sinusoidal or cosine waveform by placing an optical mask called a distortion removal mask at the edge of the light-receiving part and superimposing another waveform on the trapezoidal waveform. However, by placing a distortion removal mask, a new problem arose: the total amount of light received at the light-receiving part decreased, worsening the signal-to-noise ratio of the received light signal.

[0007] Therefore, when optically detecting the movement of a moving part in which multiple identifiers are provided at predetermined intervals, there is a need for an encoder detection unit and an encoder device that can reduce the distortion component of the received signal obtained by the light receiving unit without reducing the amount of received light.

[0008] The present invention aims to provide an encoder detection unit and an encoder device that can reduce the distortion component without reducing the amount of light received when optically detecting the movement of a moving part in which a plurality of identifiers are provided at predetermined intervals. [Means for solving the problem]

[0009] The encoder detection unit according to this invention is an encoder detection unit that optically detects the movement of a moving part, wherein the moving part is provided with a plurality of identifiers that transmit or reflect irradiated light at predetermined intervals, and the encoder detection unit comprises a light-emitting unit that irradiates light onto the identifiers, and a light-receiving unit that receives light L transmitted or reflected from the identifiers and generates a light-receiving signal, wherein when the direction of movement of light accompanying the movement of the moving part is defined as the first direction and the direction perpendicular to the first direction is defined as the second direction, the light-receiving region of the light-receiving unit has an incidence start end where the light-receiving area increases in the first and second directions when light transmitted or reflected from the identifiers begins to enter the light-receiving region as the moving part moves, and an incidence end end where the light-receiving area decreases in the first and second directions when light transmitted or reflected from the identifiers ends to enter the light-receiving region as the moving part moves.

[0010] In the encoder detection unit according to this invention, the incident start end and the incident end are formed to be inclined from the second direction toward the first direction.

[0011] In the encoder detection unit according to this invention, the incidence start end and the incidence end are formed in a straight line.

[0012] In the encoder detection unit according to this invention, the incidence start end and the incidence end are formed in a curved shape.

[0013] In the encoder detection unit according to this invention, the incidence start end and the incidence end are formed in a curved shape that includes either a sine curve or a cosine curve, or the square root of either a sine curve or a cosine curve.

[0014] In the encoder detection unit according to this invention, the light receiving unit is configured to include a plurality of regions in the first direction as a light receiving region.

[0015] The encoder device according to this invention comprises a moving part, a plurality of identifiers provided on the moving part at predetermined intervals, an encoder detection unit comprising a light-emitting part and a light-receiving part, which detects light transmitted through or reflected by the identifiers, and an encoder processing unit which processes the received light signal obtained by the encoder detection unit and calculates the rotation angle of the moving part. [Effects of the Invention]

[0016] According to this invention, when optically detecting the movement of a moving part in which multiple identifiers are provided at predetermined intervals, it is possible to provide an encoder detection unit and an encoder device that can reduce the distortion component without reducing the amount of light received in the light-receiving unit with respect to the light-receiving signal obtained by the light-receiving unit. [Brief explanation of the drawing]

[0017] [Figure 1] This is an explanatory diagram showing the change in the shape of the light-receiving region and the light-receiving area of ​​the encoder detection unit in Embodiment 1. [Figure 2] This is a configuration diagram showing the overall configuration of the encoder device in Embodiment 1. [Figure 3]It is a configuration diagram showing the overall configuration of the encoder device in Embodiment 1. [Figure 4] It is an explanatory diagram showing changes in the shapes and light-receiving areas of a plurality of light-receiving regions of the encoder detection unit in Embodiment 1. [Figure 5] It is an explanatory diagram showing an example of the shapes and arrangements of a plurality of light-receiving regions of the encoder detection unit in Embodiment 1. [Figure 6] It is an explanatory diagram showing the waveform of the light-receiving signal according to the shape of the light-receiving region of the encoder detection unit in Embodiment 1. [Figure 7] It is a characteristic diagram showing the intensity distribution of harmonic components included in the light-receiving signal according to the shape of the light-receiving region of the encoder detection unit in Embodiment 1. [Figure 8] It is an explanatory diagram showing changes in the shape and light-receiving area of the light-receiving region of the encoder detection unit in Embodiment 2. [Figure 9] It is an explanatory diagram showing changes in the shapes and light-receiving areas of a plurality of light-receiving regions of the encoder detection unit in Embodiment 2. [Figure 10] It is an explanatory diagram showing an example of the shapes and arrangements of a plurality of light-receiving regions of the encoder detection unit in Embodiment 2. [Figure 11] It is an explanatory diagram showing another example of the shapes and arrangements of a plurality of light-receiving regions of the encoder detection unit in Embodiment 2. [Figure 12] It is an explanatory diagram showing the waveform of the light-receiving signal according to the shape of the light-receiving region of the encoder detection unit in Embodiment 2. [Figure 13] It is a characteristic diagram showing the intensity distribution of harmonic components included in the light-receiving signal according to the shape of the light-receiving region of the encoder detection unit in Embodiment 2. [Figure 14] It is an explanatory diagram showing the shape of the light-receiving region of the encoder detection unit in Embodiment 3. [Figure 15] It is an explanatory diagram showing a plurality of sets of light-receiving regions included in the light-receiving part of the encoder detection unit in Embodiment 3. [Figure 16] It is an explanatory diagram showing the waveform of the light-receiving signal according to the shape of the light-receiving region of the encoder detection unit in Embodiment 3. [Figure 17] This is a characteristic diagram showing the intensity distribution of harmonic components included in the received signal according to the shape of the light-receiving area of ​​the encoder detection unit in Embodiment 3. [Figure 18] This is an explanatory diagram showing the changes in the shape and light-receiving area of ​​the light-receiving region of a conventional encoder detection unit. [Figure 19] This is an explanatory diagram showing the waveform of the received light signal according to the shape of the light-receiving area of ​​a conventional encoder detection unit. [Figure 20] This is a characteristic diagram showing the intensity distribution of harmonic components contained in the received signal according to the shape of the light-receiving area of ​​a conventional encoder detection unit. [Modes for carrying out the invention]

[0018] Embodiments of the encoder detection unit and encoder device of the present invention will be described below with reference to the drawings. In each figure, the same parts are denoted by the same reference numerals.

[0019] Embodiment 1. First, the basic overall configuration of the encoder device 100, including the encoder detection unit 140 in Embodiment 1, will be described with reference to Figures 2 and 3. Figures 2 and 3 are configuration diagrams showing the overall configuration of the encoder device 100, including the encoder device in Embodiment 1.

[0020] [Configuration of encoder device 100] The encoder device 100 calculates the rotational motion of the rotating body 1 by optically detecting the linear or rotational movement of the moving part 120. In Embodiment 1, the rotating disk 120 will be used as a specific example for the moving part 120. As shown in Figure 2 or Figure 3, the encoder device 100 mainly comprises a rotating shaft 110, a rotating disk 120, an encoder detection unit 140, and an encoder processing unit 150.

[0021] The rotating disk 120 is provided with multiple identifiers 130 at predetermined intervals, which transmit or reflect the irradiated light. The rotating disk 120 is connected to the rotating body 1 by a rotating shaft 110. Therefore, the rotating disk 120 rotates at the same rotational speed as the rotating body 1.

[0022] The identifiers 130 transmit or reflect the irradiated light and are arranged radially on the rotating disk 120 at predetermined intervals, forming an annular shape overall. When the identifiers 130 transmit light, radial slits acting as light-transmitting windows are arranged on the rotating disk 120 at predetermined intervals, as shown in Figure 2. When the identifiers 130 reflect light, radial reflection patterns are arranged on the rotating disk 120 at predetermined intervals, as shown in Figure 3.

[0023] The encoder detection unit 140 comprises a light-emitting unit 141 and a light-receiving unit 142. The light-emitting unit 141 emits light toward the identifier 130 of the rotating disk 120. The light-receiving unit 142 either detects the light emitted from the light-emitting unit that passes through the identifier 130, as shown in Figure 2, or detects the light emitted from the light-emitting unit that is reflected by the identifier 130, as shown in Figure 3.

[0024] The encoder processing unit 150 processes the light received signal generated by the light receiving unit 142 and calculates the rotation angle θ of the rotating disk 120. The encoder processing unit 150 outputs the calculated rotation angle θ to an external device.

[0025] [Configuration of the light receiving unit 142 in the encoder detection unit 140] The configuration of the light receiving unit 142 in the encoder detection unit 140 will be described below with reference to Figure 1. Figure 1 is an explanatory diagram showing the shape of the light receiving area 1420 and the change in the light receiving area of ​​the encoder detection unit 140 in Embodiment 1.

[0026] The characteristics of the light-receiving region 1420 will be explained in detail below, using a single light-receiving region 1420 as a specific example, with reference to Figure 1. In the following description, the light L transmitted or reflected from the identifier 130 as the rotating disk 120 rotates will be simply referred to as "light L," the direction of movement of light L as the rotating disk 120 rotates will be referred to as the first direction, and the direction perpendicular to the first direction will be referred to as the second direction. Furthermore, the shape of the light L transmitted or reflected from the identifier 130 will be assumed to be rectangular. The light-receiving region 1420 is enclosed by an incidence start end 1421, an incidence end 1422, an upper base 1423, and a lower base 1424. The incidence start end 1421 is the end into which light L is incident before the incidence end end 1422. The incidence start end 1421 is formed in a straight line inclined from the second direction toward the first direction such that the light-receiving area increases in both the first and second directions when light L begins to be incident on the light-receiving region 1420. The incident end end 1422 is the end where light L continues to be incident beyond the incident start end 1421. The incident end end 1422 is formed in a straight line inclined from the second direction toward the first direction such that the light-receiving area decreases in both the first and second directions when the light L ends its incident in the light-receiving region 1420. The upper base 1423 is formed along a first direction so as to connect one end of the incident start end 1421 and the incident end end 1422. The lower base 1424 is formed parallel to the upper base 1423 and along the first direction so as to connect the other end of the incident start end 1421 and the incident end end 1422. As a result, the light-receiving region 1420 is formed in a shape close to a parallelogram, as shown in Figure 1(a). Note that the inclination between the incident start end 1421 and the incident end end 1422 may be in the opposite direction to that shown in Figure 1(a). Also, the inclination between the incident start end 1421 and the incident end end 1422 may be in different directions. In this case, the light-receiving region 1420 will be trapezoidal in shape.

[0027] [Explanation of the change in light-receiving area in light-receiving region 1420] The following describes the change in the light-receiving area in the light-receiving region 1420 in response to the movement of light L. Here, the light-receiving area refers to the area in the light-receiving region 1420 that is actually receiving light L. The leading end in the direction of light L's movement will be called the leading end L11, and the trailing end in the direction of light L's movement will be called the trailing end L12. In Figure 1(b), the leading edge L11 of the light beam L begins to enter a portion of the incident start end 1421 of the light-receiving region 1420. After a certain period of time has elapsed, in Figure 1(c), the leading edge L11 of the light beam L moves further to the right along the first direction in the figure so as to include the incident start end 1421 of the light-receiving region 1420. Comparing the light-receiving area b1 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 1(b) with the light-receiving area c1 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 1(c), it can be seen that as light L moves, the light-receiving area c1 increases in both the first and second directions compared to the light-receiving area b1.

[0028] In Figure 1(d), the trailing end L12 of the light L is incident on a portion of the incident end 1422 of the light-receiving region 1420. After a certain period of time has elapsed, in Figure 1(e), the trailing end L12 of the light L moves further to the right along the first direction in the figure, including the incident end 1422 of the light-receiving region 1420. Comparing the light-receiving area d2 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 1(d) with the light-receiving area e2 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 1(e), it can be seen that as light L moves, the light-receiving area e2 decreases compared to the light-receiving area d2 in both the first and second directions.

[0029] [Light reception status in multiple light-receiving areas 1420] The configuration of the light-receiving section 142, which includes multiple light-receiving regions 1420 in the encoder detection section 140, will be described below with reference to Figure 4. Figure 4 is an explanatory diagram showing the shape of the multiple light-receiving regions 1420 and the change in light-receiving area in the light-receiving section 142 of the encoder detection section 140 in Embodiment 1. As shown in Figure 4, the light-receiving unit 142 may be used in a continuous configuration of multiple parallelogram-shaped light-receiving areas 1420. In Figure 4, for processing by the encoder processing unit 150, the light-receiving area 1420 is shown to be composed of a total of two units, with four areas a, b / , a / , b having different phases, using a phase of 0° to 360° as the basic unit. In the following explanation, the light L0 transmitted or reflected from the identifier 130 as the rotating disk 120 rotates will be simply referred to as "light L0", the light L1 transmitted or reflected from the identifier 130 as the rotating disk 120 rotates will be simply referred to as "light L1", the light L1 following the light L0 transmitted or reflected from the identifier 130 as the rotating disk 120 rotates will be simply referred to as "light L1", and the light L2 following the light L1 transmitted or reflected from the identifier 130 as the rotating disk 120 rotates will be simply referred to as "light L2".

[0030] The incident state of light L (light L0 to light L2) in the light-receiving region 1420 is defined as follows. In Figure 4(a), the state where the trailing end of the direction of movement of light L1 coincides with the left end of the lower base 1424 of region a in the light-receiving region 1420 is phase 0°. In Figure 4(b), the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region a in the light-receiving region 1420 is phase 45°. In Figure 4(c), the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region a in the light-receiving region 1420 and the left end of the upper base 1423 is phase 90°. In Figure 4(d), the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region b / in the light-receiving region 1420 and the center of the upper base 1423 of region a is phase 135°. In Figure 4(e), the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region b / in the light-receiving region 1420 and the right end of the upper base 1423 of region a is phase 90°. The state where it coincides with the end is phase 180°, in Figure 4(f) the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region a / and the center of the upper base 1423 of region b / in the light receiving region 1420 is phase 225°, and in Figure 4(g) the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 and the left end of the upper base 1423 of region a / in the light receiving region 1420 is phase At 270°, in Figure 4(h), the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region b in the light-receiving region 1420 and the center of the upper base 1423 of region a / is defined as phase 315°, and in Figure 4(i), the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region b in the light-receiving region 1420 and the left end of the upper base 1423 of region b is defined as phase 360°. Figures 4(a) to (e) show how light L0 and light L1 move from left to right on the paper at 45° intervals in response to the rotation of the rotating disk 120. Figures 4(f) to (h) show how light L0, light L1, and light L2 move from left to right on the paper at 45° intervals in response to the rotation of the rotating disk 120.

[0031] A specific example of the arrangement of multiple light-receiving regions 1420 in the light-receiving unit 142 of Embodiment 1 will be explained with reference to Figure 5. Figure 5 is an explanatory diagram showing an example of the shape and arrangement of multiple light-receiving regions 1420 in the light-receiving unit 142 of the encoder detection unit 140 in Embodiment 1. In Figure 5, the light-receiving section 142 is provided with an upper first light-receiving region row 1420A, which consists of 10 units per row, with four basic units of a, b, a / , and b / having different phases, and a lower second light-receiving region row 1420B, which also consists of 10 units per row. With this configuration, there is no need to leave gaps in the rows, so light can be received efficiently. Furthermore, in the light-receiving unit 142, the number of basic units and the number of rows per column of the light-receiving area 1420 are not limited to the specific example in Figure 5, but can be determined arbitrarily. Also, the order in which the areas constituting the basic units are arranged is not limited to a,b,a / ,b / , but can be any order such as a,b / ,a / ,b, or a,a / ,b,b / .

[0032] [Waveform of the received light signal under changes in light-receiving area] The waveform of the received light signal generated in the light-receiving region 1420, where the light-receiving area increases or decreases in the first and second directions as the light L moves, will be explained with reference to Figure 6. Figure 6 is an explanatory diagram showing the waveform of the received light signal according to the shape of the light-receiving region 1420 of the encoder detection unit 140 in Embodiment 1. In Figure 6, the horizontal axis shows the phase of light L in the light-receiving region 1420 over time, and the vertical axis shows the light intensity. The phase on the horizontal axis of Figure 6 corresponds to 0° to 360° as shown in Figures 4(a) to (i). The light intensity on the vertical axis of Figure 6 corresponds to the change in the light-receiving area in Figures 1 and 4. The light-receiving region 1420 is formed by tilting the incident start end 1421 and the incident end end 1422 such that when light L begins to enter the incident start end 1421, the light-receiving area increases in both the first and second directions, and when light L ends to enter the incident end end 1422, the light-receiving area decreases in both the first and second directions. By configuring the light-receiving region 1420 in this way, the waveform of the received signal in Embodiment 1 shown in Figure 6 has a smoother slope compared to Figure 18. Therefore, the light-receiving area increases or decreases smoothly and gradually compared to the conventional trapezoidal waveform explained in Figure 18.

[0033] Figure 7 shows the distortion components due to the waveform of the received light signal in Figure 6. Figure 7 is a characteristic diagram showing the intensity distribution of harmonic components contained in the received light signal according to the shape of the light receiving area 1420 of the encoder detection unit 140 in Embodiment 1. In Figure 7, the distribution of harmonic components of the second order and above, excluding the first order (the original detected component), is shown by a solid line. For reference, the conventional harmonic component distribution shown in Figure 20 is also shown as a dashed line in Figure 7. In the characteristics of Embodiment 1 shown by the solid line in Figure 7, it can be seen that there are fewer harmonic components compared to the characteristics of the conventional harmonic components shown by the dashed line in Figure 20. In Figure 7, when the results of an experiment conducted under the same conditions as in Figure 20 were analyzed using FFT, the energy of the 2nd to 16th harmonic components was 5.8%, with the energy of the 1st harmonic component set to 100%. Therefore, the error when calculating the rotation angle from the received signal is smaller than in the conventional method.

[0034] [Effects of Embodiment 1] The encoder detection unit 140 of Embodiment 1 optically detects the rotation of the rotating disk 120, and the rotating disk 120 is provided with a plurality of identifiers 130 that transmit or reflect irradiated light at predetermined intervals, and the encoder detection unit 140 comprises a light-emitting unit 141 that irradiates light onto the identifiers 130, and a light-receiving unit 142 that receives light L transmitted or reflected by the identifiers 130 and generates a light-receiving signal, and the direction of movement of light L accompanying the rotation of the rotating disk 120 is a first direction, first direction When the direction perpendicular to the first direction is considered the second direction, the light-receiving area 1420 of the light-receiving unit 142 has an incidence start end 1421 where the light-receiving area increases in the first and second directions when light L transmitted or reflected from the identifier 130 begins to enter the light-receiving area 1420 as the rotating disk 120 rotates, and an incidence end end 1422 where the light-receiving area decreases in the first and second directions when light L transmitted or reflected from the identifier 130 ends to enter the light-receiving area 1420 as the rotating disk 120 rotates. Here, the light-receiving region 1420 is configured such that when light L begins to enter the light-receiving region 1420, the light-receiving area increases in the first and second directions, and when light L ends to enter the light-receiving region 1420, the light-receiving area decreases in the first and second directions. As a result, the waveform of the light-receiving signal at the light-receiving unit 142 has a smooth slope. Consequently, when optically detecting the rotation of a rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it becomes possible to reduce the distortion component of the light-receiving signal obtained at the light-receiving unit 142 without reducing the amount of light received.

[0035] In the encoder detection unit 140 of Embodiment 1, the incident start end 1421 and the incident end end 1422 are formed to be inclined from the second direction to the first direction. Here, when the light L begins to enter the inclined incident start end 1421, the light-receiving area increases in both the first and second directions, and when the light L ends to enter the inclined incident end end 1422, the light-receiving area decreases in both the first and second directions. By configuring the light-receiving region 1420 in this way, the waveform of the received light signal has a smooth slope. As a result, when optically detecting the rotation of a rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it becomes possible to reduce the distortion component of the received light signal obtained by the light-receiving unit 142 without reducing the amount of light received.

[0036] In the encoder detection unit 140 of Embodiment 1, the incidence start end 1421 and the incidence end end 1422 are formed in a straight line that slopes from the second direction to the first direction. Here, when the light L begins to enter the inclined incident start end 1421, the light-receiving area increases in both the first and second directions, and when the light L ends to enter the inclined incident end end 1422, the light-receiving area decreases in both the first and second directions. By configuring the light-receiving region 1420 in this way, the waveform of the received light signal has a smooth slope. As a result, when optically detecting the rotation of a rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it becomes possible to reduce the distortion component of the received light signal obtained by the light-receiving unit 142 without reducing the amount of light received.

[0037] In the encoder detection unit 140 of Embodiment 1, the light receiving unit 142 is configured as a light receiving region 1420 that includes multiple regions a, a / , b, b / in the first direction. By using the light received signals of these four light receiving regions with different phases, efficient signal processing becomes possible in the encoder processing unit 150, and the rotation of the rotating disk 120 can be accurately detected.

[0038] The encoder device 100 of Embodiment 1 includes a rotating disk 120, a plurality of identifiers 130 provided on the rotating disk 120 at predetermined intervals, an encoder detection unit 140 comprising a light-emitting unit 141 and a light-receiving unit 142 that detects light L transmitted through or reflected by the identifiers 130, and an encoder processing unit 150 that processes the received light signal obtained by the encoder detection unit 140 and calculates the rotation angle θ of the rotating disk 120. In this encoder device 100, the rotation angle of the rotating disk 120 is calculated using a light-receiving signal with a smooth tilt and low distortion obtained by the encoder detection unit 140, thus reducing the error in the calculation of the rotation angle compared to conventional methods.

[0039] Embodiment 2. Next, the light-receiving area 1420 of the light-receiving unit 142 included in the encoder detection unit 140 in Embodiment 2 will be described with reference to Figure 8. Figure 8 is an explanatory diagram showing the shape of the light-receiving area 1420 of the encoder detection unit 140 and the change in light-receiving area in Embodiment 2.

[0040] The characteristics of the light-receiving region 1420 will be explained in detail below, using a single light-receiving region 1420 as a specific example, with reference to Figure 8. The light-receiving area 1420 is formed by being surrounded by an incident start end 1421, an incident end 1422, an upper base 1423, and a lower base 1424. The incident start end 1421 is formed in a curved shape inclined from the second direction to the first direction so that the light-receiving area increases in both the first and second directions when light L begins to enter the light-receiving region 1420. The incident end end 1422 is formed in a curved shape inclined from the second direction to the first direction so that the light-receiving area decreases in both the first and second directions when light L ends to enter the light-receiving region 1420. The inclined curved incident start end 1421 and incident end end 1422 are formed by adding a component of either a sine curve or a cosine curve, or the square root of either a sine curve or a cosine curve, to the linear inclination shown in Embodiment 1. The upper base 1423 is formed along a first direction so as to connect one end of the incident start end 1421 and the incident end end 1422. The lower base 1424 is formed parallel to the upper base 1423 and along the first direction so as to connect the other end of the incident start end 1421 and the incident end end 1422. As a result, the light-receiving region 1420, as shown in Figure 8(a), has an upper base 1423 and a lower base 1424 that are parallel, and the incident start end 1421 and incident end 1422, which correspond to the legs, are composed of curves, forming a shape in which the legs of a parallelogram are replaced with curves. Note that the inclination between the incidence start end 1421 and the incidence end end 1422 may be in the opposite direction to that shown in Figure 8(a). Also, the inclination between the incidence start end 1421 and the incidence end end 1422 may be in different directions.

[0041] [Explanation of the change in light-receiving area in light-receiving region 1420] The following describes the change in the light-receiving area in the light-receiving region 1420 in response to the movement of light L. In Figure 8(b), the leading edge L11 of the light beam L begins to enter a portion of the incident start end 1421 of the light-receiving region 1420. After a certain period of time has elapsed, in Figure 8(c), the leading edge L11 of the light beam L moves further to the right along the first direction in the figure so as to include the incident start end 1421 of the light-receiving region 1420. Comparing the light-receiving area b1 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 8(b) with the light-receiving area c1 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 8(c), it can be seen that as light L moves, the light-receiving area c1 increases in both the first and second directions compared to the light-receiving area b1.

[0042] In Figure 8(d), the trailing end L12 of the light L is incident on a portion of the incident end 1422 of the light-receiving region 1420. After a certain period of time has elapsed, in Figure 8(e), the trailing end L12 of the light L moves further to the right along the first direction in the figure, including the incident end 1422 of the light-receiving region 1420. Comparing the light-receiving area d2 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 8(d) with the light-receiving area e2 due to light L within the light-receiving region 1420 enclosed by the dashed line in Figure 8(e), it can be seen that as light L moves, the light-receiving area e2 decreases compared to the light-receiving area d2 in both the first and second directions.

[0043] [Light reception status in multiple light-receiving areas 1420] The configuration of the light-receiving section 142, which includes multiple light-receiving regions 1420 in the encoder detection section 140, will be described below with reference to Figure 9. Figure 9 is an explanatory diagram showing the shape of the multiple light-receiving regions 1420 and the change in light-receiving area in the light-receiving section 142 of the encoder detection section 140 in Embodiment 2. As shown in Figure 9, the light-receiving unit 142 may be used in a configuration where multiple light-receiving regions 1420, as described in Figure 8, are arranged in a continuous manner. In Figure 9, for processing by the encoder processing unit 150, the light-receiving region 1420 is shown to be composed of a total of two units, with four regions a, b / , a / , b having different phases, using a phase of 0° to 360° as the basic unit.

[0044] The incident state of light L (light L0 to light L2) in the light-receiving region 1420 is defined as follows. In Figure 9(a), the state where the trailing end of the direction of movement of light L1 coincides with the left end of the lower base 1424 of region a in the light-receiving region 1420 is phase 0°. In Figure 9(b), the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region a in the light-receiving region 1420 is phase 45°. In Figure 9(c), the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region a in the light-receiving region 1420 and the left end of the upper base 1423 is phase 90°. In Figure 9(d), the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region b / in the light-receiving region 1420 and the center of the upper base 1423 of region a is phase 135°. In Figure 9(e), the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region b / in the light-receiving region 1420 and the right end of the upper base 1423 of region a is phase 90°. The state where it coincides with the end is phase 180°, in Figure 9(f) the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region a / and the center of the upper base 1423 of region b / in the light receiving region 1420 is phase 225°, and in Figure 9(g) the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 and the left end of the upper base 1423 of region a / in the light receiving region 1420 is phase In Figure 9(h), a phase of 315° is defined as the state where the trailing end of the direction of movement of light L1 reaches the center of the lower base 1424 of region b in the light-receiving region 1420 and the center of the upper base 1423 of region a / , and in Figure 9(i), a phase of 360° is defined as the state where the trailing end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of region b in the light-receiving region 1420 and the left end of the upper base 1423 of region b. Figures 9(a) to (e) show how light L0 and light L1 move from left to right on the paper at 45° intervals in response to the rotation of the rotating disk 120. Figures 9(f) to (h) show how light L0, light L1, and light L2 move from left to right on the paper at 45° intervals in response to the rotation of the rotating disk 120.

[0045] Specific arrangement examples of the multiple light-receiving areas 1420 in Embodiment 2 will be explained using Figures 10 and 11. Figure 10 is an explanatory diagram showing the shape and arrangement of the multiple light-receiving areas 1420 of the encoder detection unit 140 in Embodiment 2. Figure 11 is an explanatory diagram showing another example of the shape and arrangement of the multiple light-receiving areas 1420 of the encoder detection unit 140 in Embodiment 2. In Figure 10, the light-receiving unit 142 is configured to include a first light-receiving region row 1420A1 of group A, a first light-receiving region row 1420B1 of group B, a second light-receiving region row 1420A2 of group A, and a second light-receiving region row 1420B2 of group B. The first light-receiving region row 1420A1 of group A is composed of 4 units (8 regions), with two regions a and a / having different phases, each representing a basic unit (360°), and is located in the upper left row. The first light-receiving region row 1420B1 of group B is composed of 4 units (8 regions), with two regions b and b / having different phases, each representing a basic unit (360°), and is located in the upper right row. A gap of 90° in phase is provided between the first light-receiving region row 1420A1 of group A and the first light-receiving region row 1420B1 of group B. The second light-receiving region row 1420A2 of group A is composed of 4 units (8 regions), with two regions a and a / having different phases, each representing a basic unit (360°), and is located in the lower right row. The second light-receiving region row 1420B2 of group B is composed of 4 units (8 regions), with two regions b and b / having different phases, each representing a basic unit (360°), and is located in the lower left row. A gap of 90° in phase is provided between the second light-receiving region row 1420A2 of group A and the second light-receiving region row 1420B2 of group B. In this specific example, a small gap can be achieved, resulting in high efficiency. Note that the basic number of units per column and the number of columns are not limited to the specific example in Figure 10, but can be determined arbitrarily.

[0046] In Figure 11, the light-receiving unit 142 is configured to include a first light-receiving region row 1420A and a second light-receiving region row 1420B. The first light-receiving region array 1420A is located in the upper section of the light-receiving unit 142 and consists of a total of 8 units, with a total of 2 regions of a(0.5 region), a / (1 region), and a(0.5 region) with different phases, a total of 2 regions of b(0.5 region), b / (1 region), and b(0.5 region) with different phases, a total of 2 regions of a / (0.5 region), a(1 region), and a / (0.5 region) with different phases, and a total of 2 regions each of b / (0.5 region), b(1 region), and b / (0.5 region) with different phases, each forming a basic unit (360°) with a gap of 90° in phase. The second light-receiving region array 1420B is located in the lower section of the light-receiving unit 142 and similarly consists of a total of 8 units with a gap of 90° in phase. In this specific example, a light-receiving signal that is nearly symmetrical and has little distortion can be obtained. Note that the basic number of units per column and the number of columns are not limited to the specific example in Figure 11, but can be determined arbitrarily.

[0047] [Waveform of the received light signal under changes in light-receiving area] The waveform of the received light signal generated in the light-receiving region 1420, where the light-receiving area increases or decreases in the first and second directions as the light L moves, will be explained with reference to Figure 12. Figure 12 is an explanatory diagram showing the waveform of the received light signal according to the shape of the light-receiving region 1420 of the encoder detection unit 140 in Embodiment 2. In Figure 12, the horizontal axis shows the phase of light L in the light-receiving region 1420 over time, and the vertical axis shows the light intensity. The phase on the horizontal axis of Figure 12 corresponds to 0° to 360° as shown in Figures 9(a) to (i). The light intensity on the vertical axis of Figure 12 corresponds to the change in the light-receiving area in Figures 8 and 9. The light-receiving region 1420 is formed by adding a sine curve, a cosine curve, or the square root component of a sine curve or cosine curve to the slope between the incident start end 1421 and the incident end end 1422, such that the light-receiving area increases in both the first and second directions when light L begins to enter the incident start end 1421, and decreases in both the first and second directions when light L ends to enter the incident end end 1422. By configuring the light-receiving region 1420 in this way, the waveform in Figure 12 has a smoother slope that is closer to a cosine wave than the waveform shown in Figure 6.

[0048] Figure 13 shows the distortion components due to the waveform of the received light signal in Figure 12. Figure 13 is a characteristic diagram showing the intensity distribution of harmonic components contained in the received light signal according to the shape of the light receiving area 1420 of the encoder detection unit 140 in Embodiment 2. In Figure 13, the distribution of harmonic components of the second order and above, excluding the first order (the original detected component), is shown by a solid line. For reference, the conventional harmonic component distribution shown in Figure 20 is also shown in Figure 13 as a dashed line. The characteristics of Embodiment 2 shown by the solid line in Figure 13 show fewer harmonic components compared to the conventional harmonic component characteristics shown by the dashed line in Figure 20. Therefore, the error in calculating the rotation angle from the received signal is smaller than in the conventional method. Furthermore, the characteristics of Embodiment 2 shown by the solid line in Figure 13 show even fewer harmonic components than the characteristics of Embodiment 1 shown in Figure 7.

[0049] [Effects of Embodiment 2] In the encoder detection unit 140 of the second embodiment, the incidence start end 1421 and the incidence end end 1422 are formed in a curved shape that slopes from the second direction to the first direction. Here, when the light L begins to be incident on the sloped incidence start end 1421, the light-receiving area increases in the first and second directions, and when the light L ends to be incident on the sloped incidence end end 1422, the light-receiving area decreases in the first and second directions. By configuring the light-receiving region 1420 in this way, the waveform of the received light signal has a smooth slope. As a result, when optically detecting the rotation of a rotating disk 120 on which a plurality of identifiers 130 are provided at predetermined intervals, it becomes possible to reduce the distortion component of the received light signal obtained by the light-receiving unit 142 without reducing the amount of light received.

[0050] Embodiment 3. Next, the light-receiving area 1420 of the light-receiving unit 142 included in the encoder detection unit 140 in Embodiment 3 will be described with reference to Figures 14 and 15. Figure 14 is an explanatory diagram showing the shape of the light-receiving area 1420 of the encoder detection unit 140 in Embodiment 3. Figure 15 is an explanatory diagram showing multiple sets of light-receiving areas 1420 included in the light-receiving unit 142 of the encoder detection unit 140 in Embodiment 3.

[0051] Referring to Figure 14, the characteristics of the light-receiving region 1420 will be described in detail. The light-receiving region 1420 is composed of two light-receiving regions, a and a / , as a pair. Region a is composed of an incident start end 1421a, an incident end end 1422a, and a lower base 1424a. Region a / is composed of an incident start end 1421b, an incident end end 1422b, and an upper base 1423b.

[0052] Here, a portion of the incident start end 1421a, the incident end end 1422a, the incident start end 1421b, and a portion of the incident end end 1422b are formed in a curved shape that includes either a sine curve or a cosine curve, or the square root of either a sine curve or a cosine curve. Figure 14 shows an example using a sine curve. Here, the incident end end 1422a and the incident start end 1421b both use the 90° to 270° portion of the sine curve. The upper base 1423b and the lower base 1424a are formed parallel to each other. In region a, the incident start end 1421a is formed by the 0° to 90° portion of the sine curve so that the light-receiving area increases in both the first and second directions when light L begins to enter region a. The incident end end 1422a is formed by the 90° to 270° portion of the sine curve so that the light-receiving area decreases in both the first and second directions when light L ends to enter region a. On the other hand, in region a / , the incident start end 1421b is formed by the 90° to 270° portion of the sine curve so that the light-receiving area increases in the first and second directions when light L begins to be incident on region a / . The incident end end 1422b is formed by the 270° to 360° portion of the sine curve so that the light-receiving area decreases in the first and second directions when light L ends to be incident on region a / . Note that the direction of the sine curve can be either y = sinθ or y = -sinθ (with the sign reversed).

[0053] [Light reception status in multiple light-receiving areas 1420] Next, the light-receiving area 1420 of the light-receiving unit 142 included in the encoder detection unit 140 in Embodiment 3 will be described with reference to Figure 15. Figure 15 is an explanatory diagram showing multiple sets of light-receiving areas 1420 included in the light-receiving unit 142 of the encoder detection unit 140 in Embodiment 3. The light-receiving unit 142 has two sets of light-receiving regions 1420 spaced 90° apart, assuming one set of light-receiving regions 1420 is 360°. Here, the first set of light-receiving regions 1420 includes region a and region a / . The second set of light-receiving regions 1420 includes region b and region b / . If the phase of region a is set to 0°, then region a / is 90°, region b is 180°, and region b / is 270° out of phase. The light rays L (light rays L0 to L2) in the light-receiving region 1420 are arranged to occupy 180° out of 360° and move to the right in Figure 15. As a result, light rays L (light rays L0 to L2) are incident on multiple sets of light-receiving regions 1420, similar to Figure 4 of Embodiment 1 and Figure 9 of Embodiment 2.

[0054] [Waveform of the received light signal under changes in light-receiving area] The waveform of the received light signal generated in multiple sets of light-receiving regions 1420, in which the light-receiving area increases or decreases in the first and second directions as the light L moves, will be explained with reference to Figure 16. Figure 16 is an explanatory diagram showing the waveform of the received light signal according to the shape of the light-receiving region 1420 of the encoder detection unit 140 in Embodiment 3. In Figure 16, the horizontal axis represents the phase of light L in the light-receiving region 1420 over time, and the vertical axis represents the light intensity. The phase on the horizontal axis of Figure 16 corresponds to the range of 0° to 360° in the movement of light L. The light intensity on the vertical axis of Figure 16 corresponds to the change in the light-receiving area in each light-receiving region 1420.

[0055] The light receiving area increases in the first and second directions when light L begins to enter the entry starting ends 1421a and 1421b, and decreases in the first and second directions when light ends to enter the entry ending ends 1422a and 1422b. The entry starting ends 1421a and 1421b and the entry ending ends 1422a and 1422b are formed in a sinusoidal shape. By configuring the light receiving region 1420 in this way, Figure 16 shows a waveform of the received signal with a smooth cosine curve.

[0056] Figure 17 shows the distortion components due to the waveform of the received light signal in Figure 16. Figure 17 is a characteristic diagram showing the intensity distribution of harmonic components contained in the received light signal according to the shape of the light receiving area 1420 of the encoder detection unit 140 in Embodiment 3. In Figure 17, the distribution of harmonic components of the second order and above, excluding the original detected component (which is considered first order), is shown by a solid line. For reference, the conventional harmonic component distribution shown in Figure 20 is also shown as a dashed line in Figure 17. In the characteristics of Embodiment 3 shown by the solid line in Figure 17, it can be seen that the harmonic components are extremely small and close to zero compared to the characteristics of the conventional harmonic components shown by the dashed line in Figure 20. Therefore, the error when calculating the rotation angle from the received light signal is smaller than in the conventional method.

[0057] [Effects of Embodiment 3] In the encoder detection unit 140 of Embodiment 3, the incidence start end 1421 and the incidence end end 1422 are formed in a curved shape that includes either a sine curve or a cosine curve that slopes from the second direction to the first direction, or the square root of a sine curve or a cosine curve. Here, when the light L begins to enter the inclined incident start end 1421, the light-receiving area increases in both the first and second directions, and when the light L ends to enter the inclined incident end end 1422, the light-receiving area decreases in both the first and second directions. By configuring the light-receiving region 1420 in this way, the waveform of the received light signal has a smooth slope. As a result, when optically detecting the rotation of a rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it becomes possible to reduce the distortion component of the received light signal obtained by the light-receiving unit 142 without reducing the amount of light received. [Explanation of Symbols]

[0058] 1 Rotating body, 100 Encoder device, 110 Rotating shaft, 120 Rotating disk (moving part), 130 Identifier, 140 Encoder detection unit, 141 Light-emitting unit, 142 Light-receiving unit, 150 Encoder processing unit, 1420 Light-receiving area, 1421 Incidence start end, 1422 Incidence end end, 1423 Upper base, 1424 Lower base, a,b / ,a / ,b Regions with different phases, L,L0~L2 Light, θ Rotation angle.

Claims

1. An encoder detection unit (140) optically detects the movement of the moving part (120), The moving part (120) is provided with a plurality of identifiers (130) that transmit or reflect the irradiated light at predetermined intervals. The encoder detection unit (140) is A light-emitting unit (141) that illuminates the identifier (130) with light, The system includes a light receiving unit (142) that receives light (L) transmitted through or reflected by the identifier (130) and generates a light receiving signal, When the direction of movement of the light (L) accompanying the movement of the moving part (120) is defined as the first direction, and the direction perpendicular to the first direction is defined as the second direction, The light-receiving area (1420) of the light-receiving unit (142) is As the moving part (120) moves, the light (L) transmitted through or reflected by the identifier (130) begins to enter the light-receiving region (1420), and the light-receiving area increases in the first and second directions at the incident start end (1421), As the moving part (120) moves, the light (L) that has been transmitted through or reflected by the identifier (130) ends up incident on the light-receiving region (1420), and the incident end end (1422) is such that the light-receiving area decreases in the first and second directions, Encoder detection unit.

2. The incident start end (1421) and the incident end (1422) are formed to be inclined from the second direction toward the first direction. The encoder detection unit according to claim 1.

3. The incidence start end (1421) and the incidence end (1422) are formed in a straight line. The encoder detection unit according to claim 2.

4. The incident start end (1421) and the incident end (1422) are formed in a curved shape. The encoder detection unit according to claim 2.

5. The incidence start end (1421) and the incidence end (1422) are formed in a curve shape that includes either a sine curve or a cosine curve, or the square root of either a sine curve or a cosine curve. The encoder detection unit according to claim 2.

6. The encoder detection unit according to claim 1, wherein the light receiving unit (142) is configured to include a plurality of regions (a, a / , b, b / ) in the first direction as the light receiving region (1420).

7. The movable part (120) and Multiple identifiers (130) are provided at predetermined intervals on the movable part (120), An encoder detection unit (140) according to any one of claims 1 to 6, comprising a light-emitting unit (141) and a light-receiving unit (142), which detects light (L) that transmits or reflects the identifier (130), The encoder processing unit (150) processes the light received signal obtained by the encoder detection unit (140) and calculates the rotation angle (θ) of the moving unit (120), Encoder device.

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