JP2006084349A - Absolute angle detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absolute angle detection device of high resolution, small size and low cost. <P>SOLUTION: The absolute angle detection device comprises: the rotary disk 1 which is held rotatably; the 1st slit string 3 formed on the rotary disk 1 for identification of a plurality of sectors for dividing one rotation of the rotary disk 1; the optical element 5 for detecting the sectors and for outputting the differential current value I intrinsic to each sector arranged opposite to the 1st slit line 3; the 2nd slit line 4 repeatedly formed in the peripheral direction of the rotary disk 1 made to correspond to each of the plurality of sectors; and the optical elements 6 and 7 for rotational angle detection for outputting the differential current I corresponding to the rotational angle of the rotary disk 1 in each sector. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an absolute angle detection device, and more particularly, to a configuration of slit rows formed in a rotating disk and an arrangement of detection elements arranged opposite to the slit rows.

  Conventionally, an automobile has been provided with an absolute angle detection device as a rudder angle sensor. However, since an absolute angle detection device for an automobile is applied to control of a safety device such as a suspension or a wheel, a high-precision In order to realize the control, it is required to have a high resolution of about 0.5 to 2 degrees.

Conventionally, as this type of absolute angle detection device, a single code pattern row is formed on a rotating disk, and nine detection elements are arranged opposite to the code pattern row so that one sector has a resolution of 360 degrees. Two code patterns are formed, and three code pattern strings are formed on a rotating disk, and a total of nine detection elements are arranged opposite to each code pattern string. One sector is 360 degrees and the resolution is 1.125 degrees. And two code pattern rows are formed on the rotating disk, and a total of 10 detection elements are arranged opposite to each code pattern row to achieve a resolution of 0.9 degrees with 360 degrees per sector. (For example, refer to Patent Document 1) and the like have been proposed.
JP 2000-28396 A (FIGS. 1 to 4)

  However, since the absolute angle detection apparatus according to the known example includes nine or ten detection elements, a large space is required for setting these many detection elements, and there is a disadvantage that the apparatus becomes large. In addition, since the number of detection elements is large and setting a large number of detection elements requires a great amount of labor, there is a disadvantage that the cost of the apparatus increases. Furthermore, since the number of detection elements is large, it is difficult to accurately set a predetermined detection element at a predetermined position, and it is practically difficult to obtain a high-resolution absolute angle detection device.

  The present invention has been made to solve such deficiencies of the prior art, and an object of the present invention is to provide a small and low-cost absolute angle detection device with high resolution.

    In order to solve the above-described problems, the present invention provides a first absolute angle detection device that is formed on a rotating disk that is rotatably held and the rotating disk, and divides one rotation of the rotating disk into a plurality of sectors. A slit array, a sector detecting optical element that is arranged opposite to the first slit array and outputs an analog signal specific to each sector, and formed on the rotating disk corresponding to each of the plurality of sectors The second slit array and a rotation angle detecting optical element that outputs an analog signal corresponding to the rotation angle of the rotating disk in each sector are arranged so as to face the second slit array.

  According to such a configuration, only one sector detection optical element is disposed to face the first slit row, and at least one rotation angle detection optical element is provided to face the second slit row. Since the absolute angle within the rotation can be detected, the space required for setting the optical element can be reduced, and the absolute angle detector can be miniaturized. Further, since the number of optical elements is small and the setting of the optical elements becomes easy, the cost of the absolute angle detection device can be reduced. Furthermore, since the number of optical elements is small, the predetermined optical elements can be accurately set at predetermined positions, and a high-resolution absolute angle detection device can be obtained.

  In the absolute angle detecting device having the above-described configuration, the first slit row is formed in an arc shape centered on the rotation center of the rotating disk, and the rotating disk rotates at every predetermined angle. The configuration consists of a set of a plurality of slits whose distance from the center changes.

  According to such a configuration, the position of the first slit row moving on the sector detecting optical element can be changed stepwise for each sector as the rotating disk rotates. By detecting the moving position of the first slit row with respect to the sector by the sector detecting optical element, each sector can be detected with high accuracy.

  Further, in the absolute angle detection device having the above-described configuration, the second slit row is formed in a shape in which the distance from the rotation center of the rotating disk increases or decreases monotonously according to the rotation angle of the rotating disk. And a set of a plurality of slits repeated in a fixed shape for each sector.

  According to such a configuration, the position of the second slit row moving on the rotation angle detecting optical element can be changed uniformly and continuously for each sector as the rotating disk rotates. By detecting the movement position of the second slit row with respect to the detection optical element with the rotation angle detection optical element, angle detection in each sector can be performed with high accuracy.

  In the absolute angle detection device having the above-described configuration, the sector detection optical element and the rotation angle detection optical element include a light emitting element and a light receiving element arranged to face each other with the rotating disk interposed therebetween. The light receiving element has a plurality of light receiving portions divided along a dividing line, and when the first slit row or the second slit row moves between the light receiving device and the light emitting device, It is configured to include a differential output element that outputs a differential signal corresponding to a moving position of the first slit row or the second slit row with respect to a plurality of light receiving portions.

  According to such a configuration, it is possible to obtain a differential signal corresponding to the position of the first slit row moving on the sector detecting optical element and the position of the second slit row moving on the rotation angle detecting optical element. The sector detection of the rotating disk and the angle detection in each sector can be performed with high accuracy. In addition, even if the light emission intensity of the light emitting element decreases with time, the ratio of the amount of light received between the light receiving portions does not vary, so the durability of the absolute angle detection device can be improved.

  According to the present invention, in the absolute angle detecting device having the above-described configuration, the differential output element includes a first light receiving portion and a second light receiving portion that are divided along a wedge-shaped or saw-tooth shaped dividing line. The configuration is such that a photodiode is used.

  According to this configuration, by arranging the rotating disk and each optical element so that the arrangement directions of the first light receiving unit and the second light receiving unit are orthogonal to the moving direction of the first slit row and the second slit row. Since the movement of each slit row moving on each optical element in the arrangement direction of the first light receiving portion and the second light receiving portion can be detected with high sensitivity, sector detection of the rotating disk and angle detection within each sector are possible. Can be performed with high accuracy. In particular, when the first light receiving unit and the second light receiving unit are divided into two along a sawtooth dividing line in which a plurality of wedge shapes are continuous, the band of light that has passed through the slit is a sawtooth dividing line. The first and second light receiving portions are irradiated across a plurality of locations, so that when a light emitting element such as a light emitting diode having a non-uniform amount of light is used as a light emitting element, or dust or the like is applied to the light emitting element or the light receiving element. Even when foreign matter adheres, unnecessary fluctuations in the ratio of the amount of light received between the first and second light receiving units can be suppressed, and high-precision absolute angle detection can be performed.

  The absolute angle detection device of the present invention includes a rotating disk that is rotatably held, a first slit array that is formed on the rotating disk and divides one rotation of the rotating disk into a plurality of sectors, and the first slit array. And a sector detecting optical element that outputs a unique analog signal to each of the plurality of sectors, a second slit row formed in the rotating disk corresponding to each of the plurality of sectors, A rotation angle detecting optical element that is arranged opposite to the second slit row and outputs an analog signal corresponding to the rotation angle of the rotating disk in each sector, so that one piece is placed opposite the first slit row. The absolute angle within one rotation can be detected simply by providing the sector detecting optical element and by providing at least one rotational angle detecting optical element facing the second slit row, Size of the diagonal detection device, it is possible to reduce the cost.

  Hereinafter, an embodiment of an absolute angle detection apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a plan view showing the configuration of slit rows established in a rotating disk and the arrangement of optical elements with respect to the rotating disk, FIG. 2 is a sectional view taken along II-II in FIG. 1, and FIG. FIG. 4 is a plan view showing the relationship between the configuration of the light receiving element and the band-shaped light transmitted through the slit, FIG. 5 is a graph showing the output characteristics of the light receiving element in FIG. 6 is a graph showing differential current value signals output from the sector detecting optical element and the rotation angle detecting optical element.

  As shown in FIGS. 1 to 3, the absolute angle detection device of this example includes a rotating disk 1, a support 2 for the rotating disk 1, and a first slit array 3 and a second slit array formed on the rotating disk 1. 4, a sector detection optical element 5 disposed opposite to the first slit row 3, and two rotation angle detection optical elements 6, 7 disposed opposite to the second slit row 4. .

  The support body 2 includes a cylindrical base portion 2a, a ring-shaped disc mounting portion 2b erected vertically from the outer surface of the base portion 2a, and a ring-shaped disc pressing portion 2c attached to the disc mounting portion 2b. Thus, a step portion 2d for engaging the rotating disc 1 and the disc pressing portion 2c is formed on one side of the disc mounting portion 2b. The support 2 is formed with a plastic molded body.

  The rotating disk 1 is formed in a ring shape having an inner diameter substantially equal to the diameter of the stepped portion 2d and an outer diameter larger than the outer diameter of the disk mounting portion 2b, and is formed with a light-shielding plate-like body such as a metal plate, for example. Is done. The rotating disk 1 is attached to the support 2 by fitting the inner peripheral end to the step 2d and holding the outer surface of the inner peripheral part by the disk pressing part 2c. Thereby, the rotation center O of the rotating disk 1 and the rotation center O ′ of the support 2 can be matched. The disk mounting portion 2b, the rotating disk 1 and the disk pressing portion 2c are integrated by means such as adhesion or heat caulking. The rotating disk 1 and the support 2 need only be formed integrally, and both of them may be integrated by out-molding or the like.

  As shown in FIG. 1, the first slit row 3 is formed in an arc shape centering on the rotation center O of the rotating disk 1 for each of a plurality of sectors obtained by dividing one rotation of the rotating disk 1, and at every predetermined angle. And a set of a plurality of slits whose distance from the rotation center O varies. In the example of FIG. 1, a case where one rotation of the rotating disk 1 is divided into 15 sectors and one sector is set to 24 degrees is illustrated, and the first slit row 3 has eight slits 3a. , 3b, 3c, 3d, 3e, 3f, 3g, 3h.

  That is, the slit 3 a has an arc shape with a radius r centered on the rotation center O, and is formed over an angular range of two sectors from a certain reference position A on the rotating disk 1. The slit 3b has an arc shape with a radius r + s centered on the rotation center O, and is formed over an angular range of three sectors from a position rotated clockwise by one sector from the reference position A. The slit 3c has an arc shape with a radius r + 2s centered on the rotation center O, and is formed over an angular range of three sectors from a position rotated clockwise by three sectors from the reference position A. The slit 3d has an arc shape with a radius of r + 3s centered on the rotation center O, and is formed over an angular range of three sectors from a position rotated clockwise by five sectors from the reference position A. The slit 3e has an arc shape with a radius of r + 4s centered on the rotation center O, and is formed over an angular range of 3 sectors from a position rotated clockwise by 7 sectors from the reference position A. The slit 3f has an arc shape with a radius of r + 5s centered on the rotation center O, and is formed over an angular range of 3 sectors from a position rotated clockwise by 9 sectors from the reference position A. The slit 3g has an arc shape with a radius of r + 6s centered on the rotation center O, and is formed over an angular range of three sectors from a position rotated clockwise by 11 sectors from the reference position A. The slit 3h has an arc shape with a radius of r + 7s centered on the rotation center O, and is formed over an angular range of two sectors from a position rotated clockwise by 13 sectors from the reference position A. When the slits 3a to 3h are arranged in this manner, the slits 3a to 3h can be formed without being interrupted in the circumferential direction, so that a continuous detection signal can be obtained. Further, according to the above configuration, since 15 sectors can be detected by 8 slits, compared to the case of forming 15 slits having different distances from the rotation center O of the rotating disk 1 for each sector. The number of slits constituting the first slit row 3 can be halved, and the rotating disk 1 and the sector detecting optical element 5 can be downsized, and the absolute angle detecting device can be downsized.

  The second slit row 4 is formed in a shape in which the distance from the rotation center O monotonously increases or monotonously decreases according to the rotation angle of the rotary disk 1 and is repeated in a fixed shape for each sector. , 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4l, 4m, 4n, 4o. As a shape that monotonously increases or monotonously decreases in accordance with the rotation angle of the rotating disk 1, as shown in FIG.

  As shown in FIG. 3, the sector detecting optical element 5 and the rotation angle detecting optical elements 6 and 7 are composed of a light emitting element 9 and a light receiving element 10 arranged to face each other with the rotating disk 1 therebetween. Each light emitting element 9 and light receiving element 10 constituting the optical element 5 and the rotation angle detecting optical elements 6 and 7 are mounted on a single circuit board. The sector detecting optical element 5 is disposed on the moving path of the first slit row 3 as shown in FIG. Further, as shown in FIG. 1, the rotation angle detecting optical elements 6 and 7 are arranged on the moving path of the second slit row 4 so as to be separated from each other by half a sector in the circumferential direction of the rotating disk 1.

As the light emitting element 9, a light emitting diode or the like is used. The light receiving element 10 has a plurality of light receiving parts divided by a dividing line, and outputs a differential signal corresponding to the difference in the amount of light received by each light receiving part, for example, differential two-divided A photodiode is used. The light receiving element 10 in FIG. 4 has a first light receiving unit 10a and a second light receiving unit 10b that are formed in a rectangular shape as a whole and divided by a sawtooth dividing line in which a plurality of wedge shapes are continuous. The first light receiving unit 10a and the second light receiving unit 10b are differential two-divided photodiodes arranged so as to face each other on the short side, and the current value output from the first light receiving unit 10a is When I ₁ and the current value output from the second light receiving unit 15b are I ₂ ,
I = (I ₁ −I ₂ ) / (I ₁ + I ₂ )
The differential current value I calculated by the following formula is output. The light receiving element 10 is mounted on the circuit board 12 such that the arrangement direction of the first light receiving unit 10 a and the second light receiving unit 10 b matches the radial direction of the rotary disk 1.

  Therefore, the emitted light L from the light emitting element 9 that has passed through the slits 3a to 3h constituting the first slit row 3 and the slits 4a to 4o constituting the second slit row 4 is sawtoothed as shown in FIG. The first and second light receiving portions 10a and 10b are irradiated in a strip shape across a plurality of portions of the shape dividing line. Further, since the positions of the slits 3a to 3h and 4a to 4o passing over the light receiving element 10 change in the radial direction of the rotating disk 1 with the rotation of the rotating disk 1, the slits 3a to 3h and 4a to 4o are changed. As shown in FIG. 4, the transmitted light L from the light emitting element 9 is transmitted from the first light receiving part 10a side to the second light receiving part 10b side or from the second light receiving part 10b side to the first light receiving part. Move to the 10a side. As shown in FIG. 5, the differential current value I output from the light receiving element 10 is the position of each slit with respect to the light receiving element 10, that is, the irradiation position and center position of the emitted light L in the long side direction of the light receiving element 10. The sector position of the rotating disk 1 can be detected by detecting the differential current value I output from the light receiving element 10 of the sector detecting optical element 5, and the rotation angle The rotation angle in the sector can be detected by detecting the differential current value I output from the light receiving element 10 of the detection optical elements 6 and 7, and the absolute angle of the rotating disk 1 can be detected from the respective detection results. Can be requested.

  That is, the first slit row 3 is formed of a set of slits 3a to 3h, each of which is formed in an arc shape centered on the rotation center O of the rotating disk 1 and whose distance from the rotation center O changes every predetermined angle. Therefore, from the light receiving element 10 of the sector detecting optical element 5 disposed opposite thereto, as shown in FIG. 6 (a), it changes stepwise for each sector according to the rotational position of the rotating disk 1. Since the differential current value signal S1 is output, the sector position within one rotation can be detected by determining the level of the differential current value I.

  The second slit row 4 is formed in a shape in which the distance from the rotation center O monotonously increases or monotonously decreases according to the rotation angle of the rotary disk 1 and is repeated in a fixed shape for each sector. From the light receiving elements 10 of the two rotation angle detecting optical elements 6 and 7 that are arranged opposite to each other and separated by a half sector in the circumferential direction of the rotating disk 1, As shown in FIGS. 6B and 6C, differential current value signals S2 and S3 whose phases are shifted by a half sector according to the rotational position of the rotating disk 1 and change in a wave shape for each sector are output. Is done. Therefore, the angular position in each sector can be detected by detecting the differential current value I from the linear portions of the differential current value signals S2 and S3. That is, in the example of FIG. 6, the angular position within one sector is detected from the differential current value signal S3 in the angular ranges A and C, and the angular position within the same sector is detected from the differential current value signal S2 in the angular range B. To detect. In this example, the two rotation angle detecting optical elements 6 and 7 are provided. However, each of the slits constituting the second slit row 4 so that a linear differential current value signal is output for each sector. In the case where 4a to 4o are formed, it is sufficient to provide at least one rotation angle detecting optical element.

  The absolute angle detection device of this example includes a rotating disk 1 that is rotatably held, a first slit row 3 that is formed on the rotating disk 1 and divides one rotation of the rotating disk 1 into a plurality of sectors, and a first slit. A sector detecting optical element 5 disposed opposite to the column 3 and outputting a differential current value signal S1 unique to each sector, and a second formed on the rotating disk 1 corresponding to each of the plurality of sectors. A rotation angle detecting optical element 6, which is disposed opposite to the slit row 4 and the second slit row 4 and outputs differential current value signals S2, S3 corresponding to the rotation angle of the rotary disk 1 in each sector. 7, the number of detection elements can be significantly reduced as compared with the conventional absolute angle detection device, and the absolute angle detection device can be reduced in size and cost.

  In the above embodiment, the light receiving unit includes the light receiving element 10 divided by the sawtooth dividing line. However, the gist of the present invention is not limited to this, and a required differential current value signal is provided. A light receiving element having an arbitrary light receiving portion, such as a light receiving portion divided by a wedge-shaped dividing line or a spot light position sensor (PSD) using the surface resistance of a photodiode. Can be used.

It is a top view which shows the structure of the slit row | line | column established in a rotating disc, and the arrangement | sequence of the optical element with respect to a rotating disc. It is II-II sectional drawing of FIG. It is principal part sectional drawing which shows the arrangement | sequence of a rotating disk, a light emitting element, and a light receiving element. It is a top view which shows the relationship between the structure of a light receiving element, and the strip | belt-shaped light which permeate | transmitted the slit. FIG. 5 is a graph showing output characteristics of the light receiving element of FIG. 4. It is a graph which shows the differential electric current value signal output from the optical element for a sector detection, and the optical element for a rotation angle detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating disk 3 1st slit row 3a-3h Slit 4 2nd slit row 4a-4o Slit 5 Optical element for sector detection 6, 7 Optical element for rotation angle detection 9 Light emitting element 10 Light receiving element 10a First light receiving part 10b Second Light receiving section

Claims (5)

  A rotating disk held rotatably, a first slit array formed on the rotating disk and dividing one rotation of the rotating disk into a plurality of sectors, and arranged opposite to the first slit array, each sector A sector detecting optical element that outputs a unique analog signal, a second slit row formed in the rotating disk corresponding to each of the plurality of sectors, and a second slit row arranged opposite to the second slit row, An absolute angle detection device comprising: a rotation angle detection optical element that outputs an analog signal corresponding to a rotation angle of the rotating disk in a sector.   Each of the first slit rows is formed of a set of a plurality of slits that are formed in an arc shape centered on the rotation center of the rotating disk and whose distance from the rotation center of the rotating disk changes at every predetermined angle. The absolute angle detection device according to claim 1.   The second slit row is formed in a shape in which the distance from the rotation center of the rotating disk monotonously increases or decreases according to the rotation angle of the rotating disk, and a plurality of repetitions are made in a fixed shape for each sector. The absolute angle detection device according to claim 1, comprising a set of slits.   The sector detecting optical element and the rotation angle detecting optical element are composed of a light emitting element and a light receiving element arranged to face each other via the rotating disk, and the light receiving element is divided into a plurality of lines divided along a dividing line. And when the first slit row or the second slit row moves between the light receiving element and the light emitting element, the first slit row or the second slit for the plurality of light receiving portions. The absolute angle detection device according to claim 1, comprising a differential output element that outputs a differential signal corresponding to a moving position of the column.   5. The two-divided photodiode having a first light receiving portion and a second light receiving portion divided along a wedge-shaped or saw-tooth shaped dividing line is used as the differential output element. Absolute angle detection device.

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