Encoder detector and encoder device

Abstract

An encoder detector is provided that, when optically detecting the movement of a moving part having an identifier at predetermined intervals, reduces distortion components in a received light signal without reducing the amount of received light. [Solution] The moving section 120 is provided with a plurality of identifiers 130 at predetermined intervals that transmit or reflect the irradiated light, and the encoder detection section 140 includes an emitting section 141 that irradiates the identifiers 130 with light, and a light receiving section 142 that receives light L that transmits or reflects the identifiers 130 and generates a light receiving signal, and the light receiving area 1420 of the light receiving section 1422 has an incident start end 1421 where the light receiving area increases in the first and second directions as the light L that has transmitted or reflected by the identifiers 130 begins to enter the light receiving area 1420 as the moving section 120 moves, and an incident end 1422 where the light receiving area decreases in the first and second directions as the light L that has transmitted or reflected by the identifiers 130 ends to be incident on the light receiving area 1420 as the moving section 120 moves.

Description

[Technical Field]

[0001] The present invention relates to an encoder detector and an encoder device, and more particularly to an encoder detector and an encoder device that optically detect the movement of a moving part. [Background technology]

[0002] There is an encoder device that optically detects the rotational or linear movement of a moving part that has a plurality of identifiers provided at predetermined intervals. For example, one such encoder device has a rotating plate as the moving part that is provided with light-transmitting or light-reflecting portions as identifiers. This encoder device detects the rotation angle of the rotating plate using light transmitted through the light-transmitting portions or light reflected by the light-reflecting portions. There are also encoders that detect the linear movement of a rod-shaped moving part other than a rotating plate as the moving part. This type of encoder is proposed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 60-146113 Summary of the Invention [Problem to be solved by the invention]

[0004] In this encoder device, the shape of the transmitted light from the light transmitting section or the reflected light from the light reflecting section and the shape of the light receiving area of ​​the light receiving section are generally rectangular. Here, with reference to Figure 18, the movement of the transmitted light or reflected light (hereinafter simply referred to as "light") accompanying the movement of the moving section and the state of light reception in the light receiving area will be described. Figure 18 is an explanatory diagram showing the shape of the light receiving area of ​​the detector of a conventional encoder and the change in the light receiving area. 18(a) to (h), the rectangular light receiving area has four areas a, b, a / , and b / as basic units of phase 0° to 360°. Note that the light receiving area shows two basic units in total. 18(a) to 18(e) show how light L0 and light L1 move from left to right on the paper, occupying 180° of a phase of 360°, and move from 0° to 180° in 45° increments. 18(f) to 18(h) show how light L0, L1, and light L2 move from left to right on the paper, occupying 180° of a phase of 360°, and move from 225° to 315° in 45° increments.

[0005] Fig. 19 shows the waveform of the light receiving signal obtained in area a that receives any of the lights L0, L1, or L2 shown in Fig. 18. Fig. 19 is an explanatory diagram showing the waveform of the light receiving signal according to the shape of the light receiving area of ​​the detector of a conventional encoder. That is, the waveform of the light receiving signal obtained in area a that receives any of the lights L0, L1, or L2 shown in Fig. 18 is a repetition of trapezoidal waveforms whose amplitude changes trapezoidally according to the phase, as shown in Fig. 19. Note that from 0° to 90°, there is a slope of y = -ax, from 90° to 180°, there is a flat surface with y = 0, from 180° to 270° there is a slope of y = ax, and from 270° to 360° there is a flat surface with y = a constant maximum value. Compared to an ideal sine or cosine waveform, a trapezoidal waveform light-receiving signal contains multiple harmonic components as distortion components. The distortion components caused by a conventional trapezoidal waveform are shown in Figure 20. Figure 20 is a characteristic diagram showing the intensity distribution of harmonic components contained in the light-receiving signal according to the shape of the light-receiving area of ​​a conventional encoder detector. Figure 20 shows the distribution of second-order and higher harmonic components excluding the first order, with the original detected component being the first order. When FFT analysis was performed on the results of an experiment under certain conditions, the energy of the first order component was set to 100%, and the energy of the second-order to 16th-order harmonic components was found to be 21%. These harmonic components are the cause of errors when calculating the rotation angle from the received light signal.

[0006] In order to cancel out the harmonic components contained in the received light signal, an attempt has been made to place an optical mask called a distortion removal mask at the end of the light receiving section and superimpose another waveform on the trapezoidal waveform to make the trapezoidal waveform closer to a sine wave or cosine wave.However, the placement of the distortion removal mask reduces the total amount of light received at the light receiving section, which creates a new problem: the signal-to-noise ratio of the received light signal deteriorates.

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

[0008] The present invention aims to provide an encoder detection unit and an encoder device that can reduce distortion components in the light receiving signal obtained by the light receiving unit without reducing the amount of light received when optically detecting the movement of a moving unit having multiple identifiers arranged at predetermined intervals. [Means for solving the problem]

[0009] The encoder detection unit of this invention is an encoder detection unit that optically detects the movement of a moving unit, and the moving unit is provided with a plurality of identifiers that transmit or reflect irradiated light at predetermined intervals, and the encoder detection unit is equipped with an emitting unit that irradiates light onto the identifiers, and a light receiving unit that receives light L that transmits or reflects the identifiers and generates a light receiving signal, and if the direction of movement of light as the moving unit moves is defined as a first direction and the direction perpendicular to the first direction is defined as a second direction, the light receiving area of ​​the light receiving unit has an incident start end where the light receiving area increases in the first direction and the second direction when light that has transmitted or reflected by the identifier begins to enter the light receiving area as the moving unit moves, and an incident end end where the light receiving area decreases in the first direction and the second direction when light that has transmitted or reflected by the identifier stops entering the light receiving area as the moving unit moves.

[0010] In the encoder detector according to the present invention, the incidence start end and the incidence end are formed so as to be inclined from the second direction toward the first direction.

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

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

[0014] In the encoder detector according to the present invention, the light receiving section is configured to include a plurality of regions in a first direction as light receiving regions.

[0015] The encoder device of the present invention comprises a moving unit, a plurality of identifiers provided at predetermined intervals on the moving unit, an encoder detection unit having a light emitting unit and a light receiving unit and detecting light that passes through or is reflected by the identifiers, and an encoder processing unit that processes the light receiving signal obtained by the encoder detection unit and calculates the rotation angle of the moving unit. [Effects of the Invention]

[0016] According to this invention, it is possible to provide an encoder detection unit and an encoder device that can reduce distortion components in the light receiving signal obtained by the light receiving unit without reducing the amount of light received when optically detecting the movement of a moving unit having multiple identifiers arranged at predetermined intervals. [Brief explanation of the drawings]

[0017] [Figure 1] 4 is an explanatory diagram showing the shape of a light-receiving region of an encoder detection unit and changes in light-receiving area according to the first embodiment. FIG. [Figure 2] 1 is a configuration diagram showing the overall configuration of an encoder device according to a first embodiment. [Figure 3] 1 is a configuration diagram showing the overall configuration of an encoder device according to a first embodiment. [Figure 4] 4 is an explanatory diagram showing the shapes of a plurality of light-receiving regions of the encoder detection unit and changes in the light-receiving area according to the first embodiment. FIG. [Figure 5] 3A and 3B are explanatory diagrams showing examples of the shapes and arrangements of a plurality of light-receiving regions of an encoder detector according to the first embodiment. [Figure 6] 4 is an explanatory diagram showing waveforms of light-receiving signals according to the shape of a light-receiving region of an encoder detector according to the first embodiment. FIG. [Figure 7] 4 is a characteristic diagram showing the intensity distribution of harmonic components contained in a light receiving signal according to the shape of the light receiving region of the detector of the encoder in the first embodiment. FIG. [Figure 8] 10 is an explanatory diagram showing the shape of a light-receiving region of an encoder detector and changes in light-receiving area in the second embodiment. FIG. [Figure 9] 10 is an explanatory diagram showing the shape of a plurality of light-receiving regions of an encoder detection unit and changes in light-receiving area in the second embodiment. FIG. [Figure 10] 10 is an explanatory diagram showing an example of the shape and arrangement of a plurality of light-receiving regions of an encoder detector according to the second embodiment. FIG. [Figure 11] 10 is an explanatory diagram showing another example of the shape and arrangement of a plurality of light receiving regions of an encoder detector according to the second embodiment. FIG. [Figure 12] 10 is an explanatory diagram showing waveforms of light-receiving signals according to the shape of the light-receiving region of the encoder detector in the second embodiment. FIG. [Figure 13] 10 is a characteristic diagram showing the intensity distribution of harmonic components contained in a light receiving signal according to the shape of the light receiving region of the detector of the encoder in the second embodiment. FIG. [Figure 14] 11 is an explanatory diagram showing the shape of a light receiving region of an encoder detector in the third embodiment. FIG. [Figure 15] 11 is an explanatory diagram showing a plurality of sets of light-receiving regions included in a light-receiving section of an encoder detector according to a third embodiment. FIG. [Figure 16] 11 is an explanatory diagram showing waveforms of light-receiving signals according to the shape of the light-receiving region of the encoder detector in the third embodiment. FIG. [Figure 17] 11 is a characteristic diagram showing the intensity distribution of harmonic components contained in a light receiving signal according to the shape of the light receiving region of the detector of the encoder according to the third embodiment. FIG. [Figure 18]10A and 10B are explanatory diagrams showing the shape of a light receiving region of a conventional encoder detector and changes in the light receiving area. [Figure 19] 10A and 10B are explanatory diagrams showing waveforms of light-receiving signals according to the shape of the light-receiving area of ​​a conventional encoder detector. [Figure 20] 10 is a characteristic diagram showing the intensity distribution of harmonic components contained in a light receiving signal according to the shape of the light receiving area of ​​a detector in a conventional encoder. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an encoder detector and an encoder device according to the present invention will now be described with reference to the accompanying drawings. In the drawings, the same parts are designated by the same reference numerals.

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

[0020] [Configuration of Encoder Device 100] The encoder device 100 optically detects the linear movement or rotational movement of the moving part 120, thereby calculating the movement such as rotation of the rotating body 1. In the first embodiment, the explanation will be continued by taking a rotating disk 120 as a specific example of the moving part 120. As shown in FIG. 2 or FIG. 3, the encoder device 100 mainly includes a rotating shaft 110, a rotating disk 120, an encoder detection unit 140, and an encoder processing unit 150.

[0021] A plurality of identifiers 130 that transmit or reflect irradiated light are provided at predetermined intervals on the rotating disk 120. 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, are arranged radially at predetermined intervals on the rotating disk 120, and are provided in an annular shape as a whole. When the identifiers 130 transmit light, slits as radial light-transmitting windows are arranged at predetermined intervals on the rotating disk 120 as shown in Fig. 2. When the identifiers 130 reflect light, radial reflective patterns are arranged at predetermined intervals on the rotating disk 120 as shown in Fig. 3.

[0023] The encoder detection unit 140 is configured to include a light-emitting unit 141 and a light-receiving unit 142. The light-emitting unit 141 irradiates light toward the identifier 130 on the rotating disk 120. The light-receiving unit 142 detects light that is irradiated from the light-emitting unit and passes through the identifier 130 as shown in FIG. 2, or detects light that is irradiated from the light-emitting unit and reflected by the identifier 130 as shown in FIG. 3.

[0024] The encoder processing unit 150 processes the light receiving 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 section 142 in the encoder detection section 140 will be described below with reference to Fig. 1. Fig. 1 is an explanatory diagram showing the shape of the light receiving region 1420 of the encoder detection section 140 in the first embodiment and changes in the light receiving area.

[0026] The features of the light-receiving area 1420 will be described in detail below with reference to FIG. 1, taking a single light-receiving area 1420 as an example. In the following description, the light L transmitted through or reflected by the identifier 130 as the rotating disk 120 rotates will be referred to simply as "light L," the direction of movement of the 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. The shape of the light L transmitted through or reflected by the identifier 130 will be referred to as a rectangle. The light receiving region 1420 is 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 the end where light L is incident before the incident end 1422. The incident start end 1421 is formed in a linear shape that is inclined from the second direction toward the first direction so that the light receiving area increases in the first direction and the second direction when light L starts to be incident on the light receiving region 1420. The incident end portion 1422 is an end portion where the light L is incident beyond the incident start end portion 1421. The incident end portion 1422 is formed in a linear shape that is inclined from the second direction toward the first direction so that the light receiving area decreases in both the first and second directions when the light L stops being incident on the light receiving region 1420. Upper base 1423 is formed along the first direction so as to connect one end of incidence start end 1421 and one end of incidence end end 1422. Lower base 1424 is formed along the first direction and is parallel to upper base 1423 so as to connect the other end of incidence start end 1421 and one end of incidence end end 1422. As a result, the light receiving area 1420 is formed in a shape close to a parallelogram, as shown in Fig. 1(a). The inclination of the incident start end 1421 and the incident end 1422 may be opposite to that shown in Fig. 1(a). The inclination of the incident start end 1421 and the incident end 1422 may also be in different directions. In this case, the light receiving area 1420 has a trapezoidal shape.

[0027] [Explanation of changes in the light receiving area in the light receiving region 1420] The following describes changes 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 of ​​the light receiving region 1420 that actually receives light L. The leading end in the direction of movement of light L will be called leading end L11, and the trailing end in the direction of movement of light L will be called trailing end L12. 1(b), the tip L11 of the light L begins to be incident on a part of the incident start end 1421 of the light receiving area 1420. After a certain time has passed, in FIG. 1(c), the tip L11 of the light L further moves rightward along the first direction in the drawing so as to include the incident start end 1421 of the light receiving area 1420. Comparing the light receiving area b1 for light L in the light receiving area 1420 surrounded by the dashed line in (b) of Figure 1 with the light receiving area c1 for light L in the light receiving area 1420 surrounded by the dashed line in (c) of Figure 1, it can be seen that the light receiving area c1 increases more than the light receiving area b1 in the first and second directions as the light L moves.

[0028] 1(d), the rear end L12 of the light L is incident on a part of the incident end 1422 of the light receiving region 1420. After a certain time has elapsed, in FIG. 1(e), the rear end L12 of the light L further moves rightward along the first direction in the drawing, including the incident end 1422 of the light receiving region 1420. Comparing the light receiving area d2 for light L in the light receiving region 1420 surrounded by the dashed line in (d) of Figure 1 with the light receiving area e2 for light L in the light receiving region 1420 surrounded by the dashed line in (e) of Figure 1, it can be seen that the light receiving area e2 decreases in the first direction and the second direction more than the light receiving area d2 as the light L moves.

[0029] [Light receiving state in the plurality of light receiving regions 1420] The configuration of the light receiving section 142 including the plurality of light receiving regions 1420 in the encoder detection section 140 will be described below with reference to Fig. 4. Fig. 4 is an explanatory diagram showing the shape of the plurality of light receiving regions 1420 in the light receiving section 142 of the encoder detection section 140 according to the first embodiment and changes in the light receiving area. The light receiving unit 142 may be used with a plurality of parallelogram-shaped light receiving areas 1420 in a continuous state, as shown in Fig. 4. In Fig. 4, for processing by the encoder processing unit 150, the light receiving area 1420 is shown to be configured with a total of two units, with four areas a, b / , a / , b having different phases as basic units with phases from 0° to 360°. In the following description, light L0 that passes through or is reflected by identifier 130 as rotating disk 120 rotates will be referred to simply as "light L0", light L1 that passes through or is reflected by identifier 130 as rotating disk 120 rotates will be referred to simply as "light L1", light L1 that follows light L0 that passes through or is reflected by identifier 130 as rotating disk 120 rotates will be referred to simply as "light L1", and light L2 that follows light L1 that passes through or is reflected by identifier 130 as rotating disk 120 rotates will be referred to simply as "light L2".

[0030] The incidence state of light L (light L0 to light L2) on the light receiving region 1420 is defined as follows. In (a) of FIG. 4, the state in which the rear end of the movement direction of the light L1 coincides with the left end of the lower base 1424 of the region a in the light-receiving region 1420 is a phase of 0°; in (b) of FIG. 4, the state in which the rear end of the movement direction of the light L1 reaches the center of the lower base 1424 of the region a in the light-receiving region 1420 is a phase of 45°; in (c) of FIG. 4, the state in which the rear end of the movement direction of the light L1 coincides with the right end of the lower base 1424 of the region a in the light-receiving region 1420 and the left end of the upper base 1423 is a phase of 90°; in (d) of FIG. 4, the state in which the rear end of the movement direction of the light L1 coincides with the center of the lower base 1424 of the region b / in the light-receiving region 1420 and the center of the upper base 1423 of the region a is a phase of 135°; and in (e) of FIG. 4, the state in which the rear end of the movement direction of the light L1 coincides with the right end of the lower base 1424 of the region b / in the light-receiving region 1420 and the right end of the upper base 1423 of the region a is a phase of 135°. 4(f) indicates a state in which the rear end of the light L1 in the moving direction reaches the center of the lower base 1424 of the region a / and the center of the upper base 1423 of the region b / in the light receiving region 1420, a phase of 225°; and in FIG. 4(g) indicates a state in which the rear end of the light L1 in the moving direction reaches the right end of the lower base 1424 of the region a / and the left end of the upper base 1423 of the region b / in the light receiving region 1420, a phase of In (h) of Figure 4, the state in which the rear end of the direction of movement of light L1 reaches the center of the lower base 1424 of area b in the light receiving area 1420 and the center of the upper base 1423 of area a / is defined as phase 315°, and in (i) of Figure 4, the state in which the rear end of the direction of movement of light L1 coincides with the right end of the lower base 1424 of area b in the light receiving area 1420 and the left end of the upper base 1423 of area b is defined as phase 360°. 4(a) to 4(e) show how light L0 and light L1 move in 45° increments from left to right on the paper in response to the rotation of the rotary disc 120. 4(f) to 4(h) show how light L0, light L1, and light L2 move in 45° increments from left to right on the paper in response to the rotation of the rotary disc 120.

[0031] A specific example of the arrangement of the plurality of light receiving regions 1420 in the light receiving unit 142 of the first embodiment will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing an example of the shape and arrangement of the plurality of light receiving regions 1420 in the light receiving unit 142 of the encoder detection unit 140 of the first embodiment. 5, the light receiving section 142 has four regions a, b, a / , b / with different phases as basic units, and is provided with an upper first light receiving region row 1420A consisting of 10 units per row, and a lower second light receiving region row 1420B also consisting of 10 units per row. With this configuration, there is no need to provide gaps between the rows, allowing for efficient light reception. In the light receiving section 142, the number of basic units per row and the number of rows of the light receiving region 1420 are not limited to the specific example shown in Fig. 5, but can be determined arbitrarily. Furthermore, the arrangement order of the regions constituting the basic units is not limited to a, b, a / , b / , but can be any arrangement such as a, b / , a / , b, or a, a / , b, b / .

[0032] [Waveform of light receiving signal when light receiving area changes] The waveform of the light receiving signal generated in the light receiving region 1420, whose light receiving area increases or decreases in the first and second directions as the light L moves, will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram showing the waveform of the light receiving signal according to the shape of the light receiving region 1420 of the encoder detection unit 140 in the first embodiment. 6, the horizontal axis represents the phase of light L in the light-receiving region 1420 over time, and the vertical axis represents the amount of light. The phase on the horizontal axis in FIG. 6 corresponds to 0° to 360° shown in (a) to (i) in FIG. 4. The amount of light on the vertical axis in FIG. 6 corresponds to the change in the light-receiving area in FIGS. 1 and 4. The light receiving area 1420 is formed by inclining the incident start end 1421 and the incident end 1422 so that the light receiving area increases in the first and second directions when light L starts to be incident on the incident start end 1421 and decreases in the first and second directions when light L stops being incident on the incident end end 1422. By configuring the light receiving area 1420 in this manner, the waveform of the light receiving signal of the first embodiment shown in FIG. 6 has a smoother slope than that of FIG. 18. Therefore, the light receiving area gradually increases or decreases more smoothly than the conventional trapezoidal waveform described in FIG. 18.

[0033] Fig. 7 shows distortion components due to the waveform of the light receiving signal in Fig. 6. Fig. 7 is a characteristic diagram showing the intensity distribution of harmonic components contained in the light receiving signal according to the shape of the light receiving region 1420 of the encoder detection unit 140 in the first embodiment. In Fig. 7, the original detected component is regarded as the first order, and the distribution of second-order and higher harmonic components excluding the first order is shown by a solid line. For reference, the distribution of the conventional harmonic components shown in Fig. 20 is also shown by a dashed line in Fig. 7. It can be seen that the characteristics of the first embodiment shown by the solid line in Fig. 7 have fewer harmonic components than the conventional harmonic component characteristics shown by the dashed-dotted line in Fig. 20. In Fig. 7, when an FFT analysis was performed on the results of an experiment under the same conditions as Fig. 20, the energy of the 2nd to 16th harmonic components was 5.8%, assuming the energy of the 1st component to be 100%. This means that the error when calculating the rotation angle from the received light signal is smaller than in the past.

[0034] [Effects of the First Embodiment] The encoder detection unit 140 of the first embodiment optically detects the rotation of the rotary disk 120. The rotary disk 120 is provided with a plurality of identifiers 130 that transmit or reflect irradiated light at predetermined intervals. The encoder detection unit 140 includes a light emitting unit 141 that irradiates the identifiers 130 with light, and a light receiving unit 142 that receives light L that transmits or reflects the identifiers 130 and generates a light receiving signal. The encoder detection unit 140 detects the direction of movement of the light L accompanying the rotation of the rotary disk 120 as a first direction, a second direction, and a third direction. When the direction perpendicular to the identifier 130 is defined as the second direction, the light receiving area 1420 of the light receiving unit 142 has an incident start end 1421 where the light receiving area increases in the first direction and the second direction when the light L that has passed through or reflected by the identifier 130 begins to be incident on the light receiving area 1420 as the rotating disk 120 rotates, and an incident end 1422 where the light receiving area decreases in the first direction and the second direction when the light L that has passed through or reflected by the identifier 130 ends being incident on the light receiving area 1420 as the rotating disk 120 rotates. Here, by configuring the light receiving region 1420 so that the light receiving area increases in the first and second directions when the light L starts to be incident on the light receiving region 1420 and decreases in the first and second directions when the light L stops being incident on the light receiving region 1420, the waveform of the light receiving signal at the light receiving unit 142 has a smooth slope. As a result, when optically detecting the rotation of the rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it is possible to reduce distortion components in the light receiving signal obtained by the light receiving unit 142 without reducing the amount of light received.

[0035] In the encoder detector 140 of the first embodiment, the entrance start end 1421 and the entrance end 1422 are formed so as to be inclined from the second direction toward the first direction. Here, when light L starts to be incident on the inclined incident start end 1421, the light receiving area increases in the first and second directions, and when light L stops being incident on the inclined incident end 1422, the light receiving area decreases in the first and second directions. By configuring the light receiving region 1420 in this manner, the waveform of the light receiving signal has a smooth slope. As a result, when optically detecting the rotation of the rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it is possible to reduce distortion components in the light receiving signal obtained by the light receiving unit 142 without reducing the amount of light received.

[0036] In the encoder detector 140 of the first embodiment, the entrance start end 1421 and the entrance end 1422 are formed in a linear shape that is inclined from the second direction toward the first direction. Here, when light L starts to be incident on the inclined incident start end 1421, the light receiving area increases in the first and second directions, and when light L stops being incident on the inclined incident end 1422, the light receiving area decreases in the first and second directions. By configuring the light receiving region 1420 in this manner, the waveform of the light receiving signal has a smooth slope. As a result, when optically detecting the rotation of the rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it is possible to reduce distortion components in the light receiving signal obtained by the light receiving unit 142 without reducing the amount of light received.

[0037] In the encoder detection unit 140 of the first embodiment, 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. By using the light receiving 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 arranged at predetermined intervals on the rotating disk 120, an encoder detection unit 140 described above that includes a light emitting unit 141 and a light receiving unit 142 and detects light L that passes through or is reflected by the identifiers 130, and an encoder processing unit 150 that processes the light receiving 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 slope and little distortion obtained by the encoder detector 140, so errors when calculating the rotation angle are smaller than in the past.

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

[0040] The features of the light-receiving area 1420 will be described in detail below with reference to FIG. 8, taking a single light-receiving area 1420 as a specific example. The light receiving region 1420 is 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 that is inclined from the second direction toward the first direction so that the light receiving area increases in both the first and second directions when light L starts to be incident on the light receiving region 1420. The incident end end 1422 is formed in a curved shape that is inclined from the second direction toward the first direction so that the light receiving area decreases in both the first and second directions when light L stops being incident on the light receiving region 1420. The inclined curved incident start end 1421 and incident end end 1422 are formed by adding a sine curve, a cosine curve, or a square root of a sine curve or a cosine curve to the linear slope shown in the first embodiment. Upper base 1423 is formed along the first direction so as to connect one end of incidence start end 1421 and one end of incidence end end 1422. Lower base 1424 is formed along the first direction and is parallel to upper base 1423 so as to connect the other end of incidence start end 1421 and one end of incidence end end 1422. As a result, as shown in (a) of Figure 8, the light receiving area 1420 has an upper base 1423 and a lower base 1424 that are parallel to each other, and the incident start end 1421 and the incident end 1422, which correspond to the legs, are formed as curves, so that the legs of a parallelogram are replaced with curves. The inclination of the incidence start end 1421 and the incidence end 1422 may be opposite to that shown in (a) of Figure 8. Also, the inclination of the incidence start end 1421 and the incidence end 1422 may be in different directions.

[0041] [Explanation of changes in the light receiving area in the light receiving region 1420] The change in the light receiving area of ​​the light receiving region 1420 in response to the movement of the light L will be described below. 8(b), the tip L11 of the light L begins to be incident on a part of the incident start end 1421 of the light receiving area 1420. After a certain time has passed, in FIG. 8(c), the tip L11 of the light L further moves rightward along the first direction in the drawing so as to include the incident start end 1421 of the light receiving area 1420. Comparing the light receiving area b1 for light L in the light receiving region 1420 surrounded by the dashed line in (b) of Figure 8 with the light receiving area c1 for light L in the light receiving region 1420 surrounded by the dashed line in (c) of Figure 8, it can be seen that the light receiving area c1 increases in the first direction and the second direction more than the light receiving area b1 as the light L moves.

[0042] 8(d), the rear end L12 of the light L is incident on a part of the incident end 1422 of the light receiving region 1420. In FIG. 8(e) after a certain time has passed, the rear end L12 of the light L further moves rightward along the first direction in the drawing while including the incident end 1422 of the light receiving region 1420. Comparing the light receiving area d2 for light L in the light receiving region 1420 surrounded by the dashed line in (d) of Figure 8 with the light receiving area e2 for light L in the light receiving region 1420 surrounded by the dashed line in (e) of Figure 8, it can be seen that the light receiving area e2 decreases in the first direction and the second direction more than the light receiving area d2 as the light L moves.

[0043] [Light receiving state in the plurality of light receiving regions 1420] The configuration of the light receiving section 142 including the plurality of light receiving regions 1420 in the encoder detection section 140 will be described below with reference to Fig. 9. Fig. 9 is an explanatory diagram showing the shape of the plurality of light receiving regions 1420 in the light receiving section 142 of the encoder detection section 140 according to the second embodiment and changes in the light receiving area. As shown in Fig. 9, the light receiving unit 142 may use a plurality of consecutive light receiving areas 1420 described in Fig. 8. Fig. 9 shows that, for processing by the encoder processing unit 150, the light receiving area 1420 is configured as a total of two units, with four areas a, b / , a / , b having different phases as basic units with phases from 0° to 360°.

[0044] The incidence state of light L (light L0 to light L2) on the light receiving region 1420 is defined as follows. In (a) of Figure 9, the state in which the rear end of the movement direction of light L1 coincides with the left end of the lower base 1424 of region a in the light-receiving region 1420 is represented by a phase of 0°; in (b) of Figure 9, the state in which the rear end of the movement direction of light L1 reaches the center of the lower base 1424 of region a in the light-receiving region 1420 is represented by a phase of 45°; in (c) of Figure 9, the state in which the rear end of the movement direction 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 of region a in the light-receiving region 1420 is represented by a phase of 90°; in (d) of Figure 9, the state in which the rear end of the movement direction of light L1 coincides with 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 in the light-receiving region 1420 is represented by a phase of 135°; and in (e) of Figure 9, the state in which the rear end of the movement direction 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 in the light-receiving region 1420. 9(f) indicates a state in which the rear end of the light L1 in the moving direction reaches the center of the lower base 1424 of the region a / and the center of the upper base 1423 of the region b / in the light receiving region 1420, a phase of 225°; and in FIG. 9(g) indicates a state in which the rear end of the light L1 in the moving direction reaches the right end of the lower base 1424 of the region a / and the left end of the upper base 1423 of the region b / in the light receiving region 1420, a phase of 9(h), the state in which the rear 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 FIG. 9(i), the state in which the rear 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°. 9(a) to 9(e) show how light L0 and light L1 move in 45° increments from left to right on the paper in response to the rotation of the rotary disc 120. 9(f) to 9(h) show how light L0, light L1, and light L2 move in 45° increments from left to right on the paper in response to the rotation of the rotary disc 120.

[0045] A specific example of the arrangement of the plurality of light receiving regions 1420 in the second embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is an explanatory diagram showing the shape and arrangement of the plurality of light receiving regions 1420 of the encoder detection unit 140 in the second embodiment. Fig. 11 is an explanatory diagram showing another example of the shape and arrangement of the plurality of light receiving regions 1420 of the encoder detection unit 140 in the second embodiment. In FIG. 10, the light receiving section 142 is configured to include an A group first light receiving region row 1420A1, a B group first light receiving region row 1420B1, an A group second light receiving region row 1420A2, and a B group second light receiving region row 1420B2. The A-group first light-receiving region row 1420A1 is arranged in the upper left row, with two regions a and a / that are out of phase forming a basic unit (360°), and is composed of four units (8 regions). The B-group first light-receiving region row 1420B1 is arranged in the upper right row, with two regions b and b / that are out of phase forming a basic unit (360°), and is composed of four units (8 regions). A gap of 90° phase is provided between the A-group first light-receiving region row 1420A1 and the B-group first light-receiving region row 1420B1. The A-group second light-receiving region row 1420A2 is arranged in the lower right row, with two regions a and a / that are out of phase forming a basic unit (360°), and is composed of four units (8 regions). The B-group second light-receiving region row 1420B2 is arranged in the lower left row, with two regions b and b / that are out of phase forming a basic unit (360°), and is composed of four units (8 regions). A gap of a phase of 90° is provided between the A group second light receiving region row 1420A2 and the B group second light receiving region row 1420B2. In this specific example, the gap is small, allowing for high efficiency. The number of basic units per row and the number of rows are not limited to the specific example shown in FIG. 10, and can be determined arbitrarily.

[0046] In FIG. 11, the light receiving section 142 is configured to include a first light receiving region array 1420A and a second light receiving region array 1420B. The first light-receiving region array 1420A is arranged in the upper section of the light-receiving unit 142 and is composed of a total of eight units, with a 90° phase gap between each unit, with each unit consisting of two regions of different phases: a(0.5 region), a / (1 region), and a(0.5 region); two regions of different phases: b(0.5 region), b / (1 region), and b(0.5 region); two regions of different phases: a / (0.5 region), a(1 region), and a / (0.5 region); and two regions of different phases: b / (0.5 region), b(1 region), and b / (0.5 region). This example provides a nearly symmetrical light-receiving signal with little distortion. The number of basic units per row and the number of rows are not limited to the specific example shown in FIG. 11, and can be determined arbitrarily.

[0047] [Waveform of light receiving signal when light receiving area changes] The waveform of the light receiving signal generated in the light receiving region 1420, whose light receiving area increases or decreases in the first and second directions as the light L moves, will be described with reference to Fig. 12. Fig. 12 is an explanatory diagram showing the waveform of the light receiving signal according to the shape of the light receiving region 1420 of the encoder detection unit 140 in the second embodiment. 12, the horizontal axis represents the phase of light L in the light-receiving region 1420 over time, and the vertical axis represents the amount of light. The phase on the horizontal axis in FIG. 12 corresponds to 0° to 360° shown in (a) to (i) in FIG. 9. The amount of light on the vertical axis in FIG. 12 corresponds to the change in the light-receiving area in FIGS. 8 and 9. The light receiving area 1420 is formed by adding a sine or cosine component, or a square root of a sine or cosine component, to the slope between the incident start end 1421 and the incident end 1422 so that the light receiving area increases in the first and second directions when light L starts to be incident on the incident start end 1421 and decreases in the first and second directions when light L stops being incident on the incident end 1422. By configuring the light receiving area 1420 in this way, the waveform in FIG. 12 has a smoother slope closer to a cosine wave than the waveform shown in FIG. 6.

[0048] Fig. 13 shows distortion components due to the waveform of the light receiving signal in Fig. 12. Fig. 13 is a characteristic diagram showing the intensity distribution of harmonic components contained in the light receiving signal according to the shape of the light receiving region 1420 of the encoder detection unit 140 in the second embodiment. In FIG. 13, the original detected component is defined as the first order, and the distribution of second-order and higher harmonic components excluding the first order is shown by a solid line. For reference, the distribution of conventional harmonic components shown in FIG. 20 is also shown by a dashed line in FIG. 13. It can be seen that the characteristics of the second embodiment shown by the solid line in FIG. 13 have fewer harmonic components than the characteristics of the conventional harmonic components shown by the dashed line in FIG. 20. This results in smaller errors when calculating the rotation angle from the received light signal than in the conventional embodiment. The characteristics of the second embodiment shown by the solid line in FIG. 13 have even fewer harmonic components than the characteristics of the first embodiment shown in FIG. 7.

[0049] [Effects of the second embodiment] In the encoder detector 140 of the second embodiment, the incident start end 1421 and the incident end 1422 are formed in a curved shape that slopes from the second direction toward the first direction. Here, when the light L starts to be incident on the sloped incident start end 1421, the light receiving area increases in the first and second directions, and when the light L stops being incident on the sloped incident end 1422, the light receiving area decreases in the first and second directions. By configuring the light receiving region 1420 in this manner, the waveform of the light receiving signal has a smooth slope. As a result, when optically detecting the rotation of the rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it is possible to reduce distortion components in the light receiving 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 the third embodiment will be described with reference to Fig. 14 and Fig. 15. Fig. 14 is an explanatory diagram showing the shape of the light receiving area 1420 of the encoder detection unit 140 in the third embodiment. Fig. 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 the third embodiment.

[0051] The features of the light receiving region 1420 will be described in detail with reference to Figure 14. The light receiving region 1420 is configured as a set of two light receiving regions, a and a / . Region a is configured to be surrounded by an incident start end 1421a, an incident end end 1422a, and a lower base 1424a. Region a / is configured to be surrounded by an incident start end 1421b, an incident end end 1422b, and an upper base 1423b.

[0052] Here, a portion of incidence start end 1421a, incidence end end 1422a, incidence start end 1421b, and a portion of incidence end end 1422b are formed in a curved shape that includes a sine curve, a cosine curve, or the square root of a sine curve or a cosine curve. FIG. 14 shows an example using a sine curve. Here, incidence end end 1422a and incidence start end 1421b share the 90° to 270° portion of the sine curve. Upper base 1423b and lower base 1424a are formed parallel to each other. In region a, incident start end 1421a is formed by a portion of a sine curve ranging from 0° to 90° so that the light receiving area increases in the first and second directions when light L starts to be incident on region a. Incident end end 1422a is formed by a portion of a sine curve ranging from 90° to 270° so that the light receiving area decreases in the first and second directions when light L stops being incident on region a. On the other hand, in region a / , incident start end 1421b is formed by a 90° to 270° portion of a sine curve so that the light receiving area increases in the first and second directions when light L starts to be incident on region a / . Incident end end 1422b is formed by a 270° to 360° portion of a sine curve so that the light receiving area decreases in the first and second directions when light L stops being incident on region a / . The direction of the sine curve may be y=sinθ or y=-sinθ, which is the opposite of the positive and negative directions.

[0053] [Light receiving state in the plurality of light receiving regions 1420] Next, the light receiving areas 1420 of the light receiving unit 142 included in the encoder detection unit 140 according to the third embodiment will be described with reference to Fig. 15. Fig. 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 according to the third embodiment. In the light receiving unit 142, two sets of light receiving areas 1420 are arranged with an interval of 90°, assuming that one set of light receiving areas 1420 spans 360°. Here, the first set of light receiving areas 1420 includes area a and area a / . The second set of light receiving areas 1420 includes area b and area b / . If the phase of area a is 0°, area a / is out of phase by 90°, area b by 180°, and area b / by 270°. The light L (light L0 to light L2) in the light receiving region 1420 is arranged to occupy 180° out of 360°, and moves rightward in Fig. 15. As a result, the light L (light L0 to light L2) is incident on multiple sets of light receiving regions 1420, similar to Fig. 4 of the first embodiment and Fig. 9 of the second embodiment.

[0054] [Waveform of light receiving signal when light receiving area changes] The waveforms of the light receiving signals generated in the plurality of sets of light receiving regions 1420 whose light receiving areas increase or decrease in the first and second directions as the light L moves will be described with reference to Fig. 16. Fig. 16 is an explanatory diagram showing the waveforms of the light receiving signals according to the shapes of the light receiving regions 1420 of the encoder detection unit 140 in the third embodiment. 16, the horizontal axis represents the phase of light L in the light receiving region 1420 over time, and the vertical axis represents the amount of light. The phase on the horizontal axis in FIG. 16 corresponds to 0° to 360° in the movement of light L. The amount of light on the vertical axis in FIG. 16 corresponds to the change in the light receiving area in each light receiving region 1420.

[0055] The incident start ends 1421a and 1421b and the incident end ends 1422a and 1422b are formed in a sinusoidal waveform so that when light L starts to be incident on the incident start ends 1421a and 1421b, the light receiving area increases in the first and second directions, and when it finishes being incident on the incident end ends 1422a and 1422b, 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 light receiving signal shown in FIG. 16 has a smooth cosine wave curve.

[0056] Fig. 17 shows distortion components due to the waveform of the light receiving signal in Fig. 16. Fig. 17 is a characteristic diagram showing the intensity distribution of harmonic components contained in the light receiving signal according to the shape of the light receiving region 1420 of the encoder detection unit 140 in the third embodiment. In Fig. 17, the original detected component is regarded as the first order, and the distribution of second and higher harmonic components excluding the first order is shown by a solid line. For reference, the distribution of the conventional harmonic components shown in Fig. 20 is also shown by a dashed line in Fig. 17. The characteristics of the third embodiment shown by the solid line in Fig. 17 show that the harmonic components are extremely small, approaching 0, compared to the conventional harmonic component characteristics shown by the dashed-dotted line in Fig. 20. This means that the error when calculating the rotation angle from the received light signal is smaller than in the past.

[0057] [Effects of the Third Embodiment] In the encoder detection unit 140 of embodiment 3, the incident start end 1421 and the incident end 1422 are formed in a curved shape that includes either a sine curve or a cosine curve that slopes from the second direction toward the first direction, or the square root of a sine curve or a cosine curve. Here, when light L starts to be incident on the inclined incident start end 1421, the light receiving area increases in the first and second directions, and when light L stops being incident on the inclined incident end 1422, the light receiving area decreases in the first and second directions. By configuring the light receiving region 1420 in this manner, the waveform of the light receiving signal has a smooth slope. As a result, when optically detecting the rotation of the rotating disk 120 on which multiple identifiers 130 are provided at predetermined intervals, it is possible to reduce distortion components in the light receiving 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 part, 141 Light emitting part, 142 Light receiving part, 150 Encoder processing part, 1420 Light receiving area, 1421 Incident start end, 1422 Incident end end, 1423 Upper base, 1424 Lower base, a, b / , a / , b Areas with different phases, L, L0 to L2 Light, θ Rotation angle.

Claims

1. an encoder detector (140) that optically detects the movement of the moving part (120), The moving unit (120) is provided with a plurality of identifiers (130) at predetermined intervals that transmit or reflect irradiated light, The encoder detector (140) a light emitting unit (141) that irradiates the identifier (130) with light; a light receiving unit (142) that receives light (L) that is transmitted through or reflected by the identifier (130) and generates a light receiving signal; When the moving direction of the light (L) accompanying the movement of the moving part (120) is defined as a first direction and the direction perpendicular to the first direction is defined as a second direction, The light receiving area (1420) of the light receiving unit (142) is an incidence start end (1421) at which the light receiving area increases in the first direction and the second direction when the light (L) transmitted through or reflected by the identifier (130) begins to be incident on the light receiving area (1420) as the moving unit (120) moves; and an incident end portion (1422) at which the light receiving area decreases in the first direction and the second direction when the light (L) transmitted through or reflected by the identifier (130) ends being incident on the light receiving area (1420) as the moving portion (120) moves, The incident start end (1421) and the incident end (1422) are The second direction is inclined toward the first direction, The curve is formed so that the slope of the curve is a sine curve, a cosine curve, or a square root of a sine curve or a cosine curve. Encoder detector.

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

3. A moving part (120) and a plurality of identifiers (130) provided at predetermined intervals on the moving part (120); an encoder detector (140) according to claim 1 or 2, which includes a light emitting unit (141) and a light receiving unit (142) and detects light (L) transmitted through or reflected by the identifier (130); an encoder processing unit (150) that processes the light receiving signal obtained by the encoder detection unit (140) and calculates the rotation angle (θ) of the moving unit (120); Encoder device.

Images