JP2006337304A - Encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance resolution for a moving amount or the like of a moving object, while restraining a cost/a size from increasing/getting large. <P>SOLUTION: This encoder is provided with a detecting plate 30 having a plurality of slits 31, and a sensor 20 having an irradiation part 21 fixed with respect to moving of the detecting plate 30 and for emitting light toward the slits 31, and having a photoreception part 22 for outputting luminous energy of a transmission light from the slits 31, as an analog signal, and a control part 10 detects detection points A-D along an arrow mark Y direction consistent with two threshold values stored in a ROM, during the moving of the detecting plate 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encoder that has a mark or a slit to be irradiated with light, and detects a moving amount, a moving direction, and the like of a moving body.

  An encoder is generally used as a device for detecting a moving amount of a moving body including a rotating body such as a motor. In general, there are types of encoders such as a reluctance type, an optical type, and a magnetic recording type. The optical encoder includes a detection plate, a photo sensor, and the like. The detection plate includes a plurality of slits that move together with the moving body and are positioned with a predetermined interval therebetween as an example along the moving direction. The photo sensor is fixed with respect to the movement of the moving body, and detects the amount of light transmitted through the slit.

  The optical encoder detects a moving amount of the moving body by detecting a slit that passes through the photosensor in the moving direction. That is, how much the moving body has moved is detected by the number of slits passing through the photosensor. Accordingly, the resolution such as the moving amount of the moving body varies depending on the arrangement interval of the slits. For this reason, the conventional optical encoder uses a plurality of photosensors with a plurality of slit rows so that the arrangement interval of the slits is reduced and the phase of the received light amount waveform is different (see, for example, Patent Document 1). ) To improve resolution. Moreover, in the structure of patent document 1 provided with the row | line | column of two rows of slits, the moving direction of a mobile body is also detected.

In recent years, with the increase in functionality and space saving of electronic devices, parts such as encoders installed inside the electronic devices are desired to be reduced in size and weight.
JP-A-3-37832

  However, in the encoder configuration in which the slit shape is reduced and the arrangement interval is reduced as described above, high etching accuracy at the time of slit formation and high position accuracy at the time of sensor attachment are required, resulting in an increase in cost. In addition, the encoder configuration with a plurality of slit rows increases the size compared to the case with a single row of slits, and requires more precision in the formation position of each row of slits and the sensor mounting position. This increases the cost.

  An object of the present invention is to provide an encoder capable of improving the resolution such as the moving amount of a moving body with a simple configuration while suppressing an increase in cost and size.

  In order to solve the above problems, the present invention has the following configuration.

(1) A detection plate that moves together with a moving body, wherein a plurality of marks or a plurality of slits are formed on the surface of the plate along the moving direction of the moving body with a predetermined interval therebetween. When,
An irradiating unit that irradiates light at a position where the plurality of marks or the plurality of slits are formed on the plate surface;
A light receiving unit that outputs an amount of reflected light or transmitted light as an analog signal according to the shape of the mark or slit of the light emitted from the irradiation unit;
The plurality of marks or the plurality of slits exhibit a shape in which at least a part is inclined with respect to the moving direction,
And a first detection means for detecting the amount of movement of the moving body by comparing the analog signal with a plurality of different threshold values.

  In this configuration, the amount of reflected or transmitted light corresponding to the shape of the mark or slit irradiated on the plate surface of the detection plate moving with the moving body is output as an analog signal. Further, the movement amount of the moving body is detected by comparing the analog signal with a plurality of threshold values.

  At this time, since at least a part of the shape of the mark or slit is inclined with respect to the moving direction, the amount of received light gradually increases or decreases with respect to the movement of the mark or slit in the moving direction. Decrease. For this reason, the waveform of the analog signal also has a shape that gradually increases or decreases for at least a part, so that even if a plurality of threshold values are set, the values do not overlap.

  Therefore, a plurality of positions of the received light amount that match a plurality of threshold values are detected from a single mark or slit, so that even if the received light amount of the single mark or slit is detected by the light receiving unit, The amount of movement is detected. Therefore, the resolution of the moving amount of the moving body is higher than the conventional configuration in which the moving amount is detected by detecting a mark or slit that passes therethrough.

(2) A detection plate that moves together with a moving body, wherein a plurality of marks or a plurality of slits are formed on the plate surface at predetermined intervals between the moving bodies along the moving direction of the moving body. When,
An irradiating unit that irradiates light at a position where the plurality of marks or the plurality of slits are formed on the plate surface;
A light receiving unit that outputs an amount of reflected light or transmitted light as an analog signal according to the shape of the mark or slit of the light emitted from the irradiation unit;
The plurality of marks or the plurality of slits exhibit a shape in which at least a part of the waveform of the analog signal increases or decreases with respect to the movement direction,
And a first detection means for detecting the amount of movement of the moving body by comparing the analog signal with a plurality of different threshold values.

  In this configuration, the amount of reflected or transmitted light corresponding to the shape of the mark or slit irradiated on the plate surface of the detection plate moving with the moving body is output as an analog signal. Further, the movement amount of the moving body is detected by comparing the analog signal with a plurality of threshold values.

  At this time, since the mark or slit has a shape in which at least a part of the waveform of the analog signal increases or decreases with respect to the movement direction, the amount of received light gradually increases with respect to the movement of the mark or slit in the movement direction. Increase or decrease. For this reason, the waveform of the analog signal also has a shape that gradually increases or decreases for at least a part, so that even if a plurality of threshold values are set, the values do not overlap.

  Therefore, a plurality of positions of the received light amount that match a plurality of threshold values are detected from a single mark or slit, so that even if the received light amount of the single mark or slit is detected by the light receiving unit, The amount of movement is detected. Therefore, the resolution of the moving amount of the moving body is higher than the conventional configuration in which the moving amount is detected by detecting a mark or slit that passes therethrough.

(3) The plurality of marks or the plurality of slits exhibit an asymmetric shape with respect to a line orthogonal to the moving direction at a position where the waveform of the analog signal has the maximum light amount or the minimum light amount,
In the waveform of the analog signal, three or more detection positions in the movement direction corresponding to the light intensity values that match each of the plurality of threshold values are detected, and between the detected three or more detection positions. A second detection means for detecting the moving direction of the moving body based on a difference in distance is provided.

  In this configuration, at the position where the waveform of the analog signal of the mark or the slit becomes the maximum light amount or the minimum light amount, the line orthogonal to the moving direction has an asymmetric shape. Further, in the analog signal waveform, the moving direction of the moving body is detected based on the difference in distance between the detection positions in the moving direction corresponding to the light quantity values that match each of the three or more threshold values. That is, since the waveform of the analog signal has an asymmetric shape in a line orthogonal to the movement direction, the distance between one detection position and each of the other two detection positions is based on at least one detection position in the movement direction. Therefore, the moving direction of the moving body is detected from this difference.

  According to the present invention, the following effects can be obtained.

  (1) Forming a shape that is inclined with respect to the moving direction in at least a part of the mark or slit, and comparing the analog signal with a plurality of different threshold values to detect the moving amount of the moving body, The resolution of the moving amount of the moving body can be improved without causing an increase in size.

  (2) A mark or slit is formed in a shape in which at least a part of the waveform of the analog signal increases or decreases with respect to the moving direction, and the moving amount of the moving body is detected by comparing the analog signal with a plurality of different threshold values. By doing so, the resolution of the moving amount of the moving body can be improved without causing an increase in cost and size.

  (3) The mark or slit is formed in an asymmetric shape in a line orthogonal to the moving direction at a position where the waveform of the analog signal has the maximum light amount or the minimum light amount, and is detected from the analog signal waveform using a plurality of threshold values. By detecting the moving direction of the moving body based on the difference in distance between each of the detection positions of more than one location, it is possible to easily detect the moving direction of the moving body without causing an increase in cost and size. Can do.

  Hereinafter, an encoder according to the best embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a simple configuration of an encoder according to an embodiment of the present invention. The encoder 1 is arranged in a main body device such as an electronic device (not shown), and includes a control unit 10, a sensor 20, and the like, and detects a moving amount of a moving body (not shown). The control unit 10 includes a CPU 11, a ROM 12, a RAM 13, and the like, and controls the entire operation of the encoder 1. The CPU 11 controls the overall operation of the encoder 1 according to the control program stored in the ROM 12. The ROM 12 stores a control program and the like. The RAM 13 temporarily stores acquired data and the like.

  The sensor 20 includes an irradiation unit 21, a light receiving unit 22, and the like, and detects the amount of light transmitted through a slit 31 provided in the detection plate 30 as shown in FIG. The detection plate 30 constitutes a part of the encoder 1 and reciprocates in the arrow Y direction (arrow Y1, Y2 direction) that is the moving direction together with the moving body. In addition, the plate surface of the detection plate 30 is formed with a plurality of slits 31 each having a triangular shape in a row in the direction of the arrow Y with an interval M therebetween. Note that the slit 31 of the present embodiment has an isosceles triangular shape.

  The sensor 20 is fixed at a position facing the position where the slit 31 is formed on the plate surface of the detection plate 30. The irradiation unit 21 irradiates light to the facing slit 31. The light receiving unit 22 is located at a position facing the irradiation unit 21 with the detection plate 30 in between, the width in the arrow Y direction is equal to or less than the interval M, and the width in the direction orthogonal to the arrow Y direction is W. The amount of transmitted light corresponding to the shape is detected. The light receiving unit 22 outputs an analog signal of the detected light amount to the control unit 10.

  For example, while the detection plate 30 is moving in the arrow Y1 direction, the waveform of the analog signal of the light amount detected by the light receiving unit 22 has a shape corresponding to the shape of the slit 31 as shown in FIG. . That is, the shape is inclined with respect to the arrow Y direction. The control unit 10 detects the amount of movement of the moving body from the received analog signal as shown in FIG. Specifically, as shown in FIG. 2B, which is stored in the ROM, the detection positions A to D in the arrow Y direction that match the two threshold values are detected, and the detection result is provided in the main body (not shown) Output to the control unit. Each threshold value is a light amount value at each position obtained by dividing the slit 31 at the same interval as the predetermined interval M in the arrow Y direction.

  The detection of the detection positions A to D corresponds to detection of the moving amount of the moving body. For example, when position B is detected after position A is detected, the moving body has moved by a distance of a predetermined interval M in the arrow Y direction by a distance between position A and position B. .

  Therefore, in this embodiment, since the amount of movement of the moving body can be detected at the four positions by detecting the light amount of the single slit 31, the amount of movement of the moving body does not increase in cost and size. Resolution can be improved. The control unit 10 corresponds to the first detection means of the present invention.

  In the present embodiment, the amount of transmitted light received according to the shape of the slit 31 is detected, but the amount of reflected light according to the shape of the slit 31 may be used, and the shape of the mark formed on the detection plate 30 instead of the slit 31. The amount of reflected light may be detected according to the above.

  Further, the shape of the slit 31 is not limited to the triangular shape shown in FIG. 2A, and a polygonal shape such as a quadrangular shape as long as at least a part thereof is inclined with respect to the arrow Y direction. It may be.

  In the present embodiment, the light amount of the width W of the slit 31 is detected using the light receiving unit 22, but it is only necessary to detect a part of the light amount including the shape of the inclined portion with respect to the moving direction of the slit 31.

  In addition, although the control part 10 is provided in the encoder 1, you may output the analog signal of light quantity from the light-receiving part 22 to the main body control part of a main body apparatus by using the main body control part as the control part 10.

(Second Embodiment)
In the present embodiment, as shown in FIG. 3A, a plurality of slits 131 are formed on the plate surface of the detection plate 130 in the direction of the arrow Y1 with an interval N between them. The slit 131 has a right triangle shape, and as shown in FIG. 3B, the slit 131 has an asymmetric shape with respect to a line orthogonal to the arrow Y1 direction at a position where the waveform of the analog signal of the transmitted light amount is the maximum light amount P. Presents. Other configurations are the same as those of the first embodiment. Note that the moving body moves only in the arrow Y1 direction shown in FIG.

  For example, as shown in FIG. 3A, while the slit 131 is moving in the arrow Y1 direction, the light receiving unit 22 outputs the analog signal shown in FIG. The control unit 10 detects the detection positions E, F, and GE ′ based on the three threshold values stored in the ROM 12 in the same manner as described above. As a result, the same effects as those of the first embodiment described above can be obtained.

  As shown in FIGS. 4A and 4B, even if the moving direction of the moving body is the two directions indicated by the arrows Y1 and Y2, it can be moved if the moving direction of the moving body is detected first. The amount can be detected.

  For example, the detection positions E, F, G, G ′, F ′, and E ′ are detected from the above three threshold values, and four of these detection positions E, F, F ′, and E ′ are in the direction of the arrow Y1. The moving direction of the moving body is detected from the difference in distance. When the slit 131 moves in the direction of the arrow Y1 shown in FIG. 4A, the control unit 10 first detects the detection positions E, F, G, and the like based on the three threshold values stored in the ROM 12. G ′, F ′, and E ′ are detected, and the distance between the detection position E and the detection position F ′ in the arrow Y direction is compared with the distance between the detection position F and the detection position E ′ in the arrow Y direction. Next, it is determined whether or not the distance between the detection positions E and F ′ is longer. If it is determined that the distance between the detection positions E and F ′ is longer, it is determined that the moving body is moving in the direction of the arrow Y1. On the contrary, when it is determined that the distance between the detection positions E and F ′ is shorter, it is determined that the moving body is moving in the direction of the arrow Y2. When the moving body moves in the direction of the arrow Y2, the detection order is reversed, so that the detection positions E ′, F ′, G ′, G, F, E shown in FIG. Detection positions E, F, G, G ′, F ′, and E ′ are detected.

  After detecting the moving direction, the moving amount is detected based on the detection positions E, F, G, E ′. Therefore, the control unit 10 corresponds to the first detection unit and the second detection unit of the present invention. When the moving body is moving in the direction of the arrow Y2, the moving amount of the moving body is detected based on the detection positions E, G ′, F ′, E ′.

  As a result, the moving direction of the moving body can be easily detected without causing an increase in cost and size.

  In the present embodiment, the moving direction of the moving body is detected using the four detection positions. However, the present invention is not particularly limited to this, and at least three detection positions are used to determine the distance from each detection position. What is necessary is just to detect a moving direction from a difference. For example, as shown in FIGS. 5A and 5B, detection positions E, F, G, H, G ′, F ′, and E ′ detected based on four threshold values are detected, and the detection position H is detected. And E may be detected based on the difference between the distance in the arrow Y direction of E and the distance of the detection positions H and E ′ in the arrow Y direction. Note that the waveform of the analog signal illustrated in FIG. 5B is a waveform when the moving body is moving in the arrow Y1 direction. At this time, the moving amount of the moving body is detected at the detection positions E, F, G, H, E ′. Conversely, when the moving body is moving in the direction of the arrow Y2, the moving amount of the moving body is detected at the detection positions E, H, G ′, F ′, and E ′.

  In the present embodiment, the moving direction of the moving body is detected using the triangular slit 131 as shown in FIGS. 4 and 5, but the present invention is not limited to this. As long as the slit 131 has an asymmetric shape in a line orthogonal to the arrow Y direction, a polygon such as a quadrangle may be used.

  In addition, when the amount of movement is detected using a mark instead of the slit 131, if the formed light is formed of a member that absorbs irradiated light, a color, or the like, the waveform of the analog signal of the reflected light of the mark is the minimum light amount. The shape of the slit 131 having an asymmetric shape in a line orthogonal to the arrow Y direction may be used.

  In these embodiments, the encoder that detects the amount of movement of the moving body that moves in the linear direction has been described. However, the present invention can also be applied to the encoder to detect the amount of rotation and the rotation direction of the rotating body. is there.

It is a block diagram which shows the simple structure of the encoder which concerns on embodiment of this invention. It is explanatory drawing which detects the light quantity reflected in the slit with which the detection board with which the encoder is equipped is equipped. It is explanatory drawing which detects the light quantity reflected in the slit with which the detection board with which the encoder is equipped is equipped. It is explanatory drawing which detects the light quantity reflected in the slit with which the detection board with which the encoder is equipped is equipped. It is explanatory drawing which detects the light quantity reflected in the slit with which the detection board with which the encoder is equipped is equipped.

Explanation of symbols

1-encoder 10-control unit 20-sensor 21-irradiation unit 22-light receiving unit 30, 130-detection plate 31, 131-slit A to H, E 'to G'-detection position

Claims (3)

A detection plate that moves together with the moving body, the detection plate having a plurality of marks or slits formed on the plate surface with a predetermined interval between each other along the moving direction of the moving body;
An irradiating unit that irradiates light at a position where the plurality of marks or the plurality of slits are formed on the plate surface;
A light receiving unit that outputs an amount of reflected light or transmitted light as an analog signal according to the shape of the mark or slit of the light irradiated from the irradiation unit;
The plurality of marks or the plurality of slits exhibit a shape in which at least a part is inclined with respect to the moving direction,
An encoder comprising: first detection means for detecting a movement amount of the moving body by comparing the analog signal with a plurality of different threshold values. A detection plate that moves together with the moving body, wherein the plate surface is formed with a plurality of marks or a plurality of slits that are located at predetermined intervals along the moving direction of the moving body;
An irradiating unit that irradiates light at a position where the plurality of marks or the plurality of slits are formed on the plate surface;
A light receiving unit that outputs an amount of reflected light or transmitted light as an analog signal according to the shape of the mark or slit of the light emitted from the irradiation unit;
The plurality of marks or the plurality of slits exhibit a shape in which at least a part of the waveform of the analog signal increases or decreases with respect to the movement direction,
An encoder comprising: first detection means for detecting a movement amount of the moving body by comparing the analog signal with a plurality of different threshold values. The plurality of marks or the plurality of slits exhibit an asymmetric shape with respect to a line orthogonal to the moving direction at a position where the waveform of the analog signal has a maximum light amount or a minimum light amount,
In the waveform of the analog signal, three or more detection positions in the movement direction corresponding to the light intensity values that match each of the plurality of threshold values are detected, and between the detected three or more detection positions. The encoder according to claim 2, further comprising second detection means for detecting the moving direction of the moving body based on a difference in distance.

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