JP2019158851A - Reflection type encoder - Google Patents

Abstract

To provide a reflection type encoder that is high in reliability.SOLUTION: A reflection type encoder includes: a scale plate that has a plurality of patterns to be provided in a first surface; a substrate that is arranged facing the first surface of the scale plate; a light emission unit that is arranged in a facing surface, of the substrate, facing the first surface, and irradiates the scale plate with irradiation light; a plurality of light reception elements that are arranged in the facing surface of the substrate, and receive reflection light to be reflected upon the pattern of the scale plate; a cover that has the scale plate, the light emission unit, and a cylindrical lateral wall part surrounding a periphery of the light reception element, and has an opening part in the lateral wall part or at least one or more notch parts; and an annular wall part that is arranged in the facing surface of the substrate, and surrounds the light emission unit and the plurality of light reception elements.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reflective encoder.

  Conventionally, a code plate that is mounted on a rotating body and has a predetermined pattern formed thereon, a first detection unit that detects the amount of rotation of the rotating body based on the predetermined pattern formed on the code plate, and the code There is an encoder characterized by having a second detection unit that detects the amount of rotation of the rotating body based on the predetermined pattern formed on the plate by a method different from that of the first detection unit (for example, , See Patent Document 1).

Japanese Patent Laid-Open No. 2007-114032

  By the way, a moving body such as a rotating body, a code plate, a cover that covers the side of the first detection unit, and the second detection unit, a housing that holds the first detection unit, or a second detection unit A gap such as an opening may be provided between the substrate to be mounted. Such a gap is used, for example, for engaging a jig when positioning the cover and the housing or the substrate.

  However, if there is such a gap, light may enter the inside from the gap and the light receiving element may be erroneously detected. In addition, foreign matters such as dust may enter inside through the gap and adhere to the reflecting surface of the moving body, which may cause malfunction.

  There is a problem that such erroneous detection and malfunction lead to a decrease in the reliability of the encoder.

  Therefore, an object is to provide a reflective encoder with high reliability.

  A reflective encoder according to an embodiment of the present invention includes a scale plate having a plurality of patterns provided on a first surface, a substrate disposed to face the first surface of the scale plate, and the first of the substrate. A light-emitting unit that is disposed on an opposing surface that faces one surface and that irradiates the scale plate with irradiation light; and a reflected light that is disposed on the opposing surface of the substrate and is reflected by the pattern of the scale plate. A cover having a plurality of light receiving elements and a cylindrical side wall surrounding the scale plate, the light emitting part, and the periphery of the light receiving element, wherein the side wall has at least one opening or notch. A cover having the above, and an annular wall portion disposed on the facing surface of the substrate and surrounding the light emitting portion and the plurality of light receiving elements.

  A highly reliable reflective encoder can be provided.

It is a figure which shows the state with which the reflection type encoder 100 of embodiment was attached to the motor. It is a figure which shows the reflective encoder 100 of embodiment. FIG. 3 is a diagram showing a substrate 101 and an optical module 120. It is a figure which shows the optical module 120, the wall part 130, and the mask board 131. FIG.

  Embodiments to which the reflective encoder of the present invention is applied will be described below.

<Embodiment>
FIG. 1 is a diagram illustrating a state in which the reflective encoder 100 according to the embodiment is attached to a motor 50. Below, it demonstrates using an XYZ coordinate system, and XY surface view is called planar view.

  The reflective encoder 100 includes a substrate 101, a scale plate 110, an optical module 120, a wall portion 130, a mask plate 131, and an encoder cover 140. Hereinafter, description will be made with reference to FIGS. 2 to 4 in addition to FIG.

  FIG. 2 is a diagram illustrating the reflective encoder 100 according to the embodiment. In FIG. 2A, a part of the reflective encoder 100 is transparently shown in a plan view. FIG. 2B shows a configuration of a side surface when the reflective encoder 100 is viewed from the XZ plane. FIG. 2C shows a side configuration of the reflective encoder 100 as viewed from the YZ plane. FIG. 3 is a diagram showing the substrate 101 and the optical module 120. FIG. 4 is a diagram illustrating the optical module 120, the wall 130, and the mask plate 131.

  Here, first, the encoder cover 140 will be described. The encoder cover 140 is made of resin and is a member having a cylindrical wall portion 140A as shown in FIG. The encoder cover 140 has a configuration in which both ends of a cylindrical wall portion 140A are opened. The encoder cover 140 is an example of a cover.

  A disc-shaped substrate 101 is connected to the end of the encoder cover 140 on the negative side of the Z-axis. The outer diameters of the encoder cover 140 and the substrate 101 are equal. In addition, a columnar casing 50 </ b> A of the motor 50 is connected to an end portion of the encoder cover 140 on the Z axis positive direction side. Here, as an example, the outer diameter of the encoder cover 140 and the outer diameter of the housing 50 </ b> A of the motor 50 are equal. The motor 50 is, for example, a servo motor. A wall portion parallel to the substrate 101 is provided on the Z axis negative direction side of the housing 50A, and the rotation shaft of the motor 50 passes through the center of the wall portion in plan view.

  The encoder cover 140 accommodates the scale plate 110, the optical module 120, and other electronic components in a space surrounded by the substrate 101 and the wall portion of the housing 50A of the motor 50.

  The cylindrical wall portion 140A of the encoder cover 140 has a notch portion 141 provided along the opening portion at the end portion on the Z-axis negative direction side, and an opening portion 142 provided in the center portion in the Z-axis direction.

  The notch portion 141 is a portion in which the end portion on the Z-axis negative direction side of the wall portion 140A is notched to the Z-axis positive direction side along the circumferential direction, and the wall portion 140A and the substrate 101 are as shown in FIG. A slit-like opening that is long in the circumferential direction is constructed.

  The opening 142 opens in a slit shape that is long in the circumferential direction along the circumferential direction at a central portion in the Z-axis direction of the wall 140A on the substantially opposite side in the circumferential direction to the notch 141.

  As an example, the notch 141 and the opening 142 are provided to engage a jig that holds the encoder cover 140 when the positions of the substrate 101, the encoder cover 140, and the motor 50 are aligned.

  Next, the substrate 101, the scale plate 110, the optical module 120, the wall portion 130, and the mask plate 131 will be described.

  The substrate 101 is a circular wiring substrate in plan view. As the substrate 101, for example, a FR-4 (Flame Retardant type 4) standard wiring substrate can be used. The optical module 120 is mounted on the surface on the Z-axis positive direction side of the substrate 101, and a circuit connected to the optical module 120 is configured on the surface on the Z-axis positive direction side and the surface on the Z-axis negative direction side. An electronic component or the like is mounted, but the illustration is omitted here.

  As an example, the scale plate 110 includes a metal or glass disc portion 110A and a rotation shaft 110B attached to the Z axis positive direction side at the center of the disc portion 110A. The rotation shaft 110 </ b> B is fixed to the rotation shaft of the motor 50. The scale plate 110 rotates around the rotation shaft 110B in the XY plane in accordance with the rotation of the rotation shaft of the motor 50. For this reason, the rotation direction and the circumferential direction of the circular scale plate 110 are the same in plan view.

  For example, the disc part 110 </ b> A of the metal scale plate 110 is parallel to the substrate 101. As shown in FIG. 2, reflecting portions 111 and 112 are provided on the surface of the scale plate 110 on the Z axis negative direction side along the outer periphery. The reflection part 111 is a reflection part for an incremental pattern, and the reflection part 112 is a reflection part for an absolute pattern. The scale plate 110 is an example of a reflecting member, and the reflecting portions 111 and 112 are examples of a reflecting pattern. The surface on the negative side of the Z-axis of the scale plate 110 is an example of a first surface.

  As an example, the reflecting portion 111 is manufactured by providing a non-reflecting portion 111A that does not reflect light (or has a lower reflectance than the reflecting portion 112) between the reflecting portions 111. The non-reflecting part 111A is produced, for example, by applying a light absorbing material that absorbs light. This is the same for the reflecting portion 112, and is produced by providing a non-reflecting portion 112A coated with a light absorbing material between the reflecting portions 112.

  The scale plate 110 reflects light emitted from the LEDs 121 of the optical module 120 to the light receiving elements 123 and 124 of the optical module 120. The reflected light emitted from the LED 121 and reflected by the reflecting portion 111 reaches the light receiving element 123, and the reflected light emitted from the LED 121 and reflected by the reflecting portion 112 reaches the light receiving element 124.

  In addition, when the scale plate 110 is made of glass, the non-reflective portions 111A and 112A are regions that transmit light, for example, and are regions that are not provided with the metal layers as the reflective portions 111 and 112.

  The widths of all the reflecting portions 111 in the circumferential direction are equal, and the widths of the reflecting portion 111 and the non-reflecting portion 111A in the circumferential direction of the scale plate 110 are equal. The reflectors 111 are provided at equal intervals (equal pitch) in the circumferential direction. The absolute pattern reflection unit 112 represents a predetermined value in binary numbers, and is configured as a code string in which all combinations of N consecutive codes are different. Since it is difficult to accurately depict the absolute pattern reflective portion 112, the absolute pattern reflective portion 112 is shown here in the same shape as the reflective portion 111 for convenience of explanation.

  The optical module 120 includes a base portion 120 </ b> A, an LED 121, and light receiving elements 123 and 124. The optical module 120 is mounted on the surface of the substrate 101 on the Z axis positive direction side and faces the scale plate 110. The base portion 120A is a rectangular and flat substrate in plan view. An LED 121 and light receiving elements 123 and 124 are disposed on the surface of the base portion 120A on the positive side in the Z-axis direction.

  The LED 121 includes a light emitting unit 121A that emits a laser at the center in plan view, and the light emitting unit 121A has a light emitting surface facing the positive Z-axis direction. That is, the LED 121 faces the surface of the scale plate 110 on the Z axis negative direction side. The LED 121 is a Lambert type, and the light diameter of the light emitting unit 121A is, for example, 30 μm to 100 μm.

  Here, FIG. 2A shows a straight line C that passes through the center of the scale plate 110 and extends in the radial direction of the scale plate 110. The light emitting unit 121A is located on the straight line C, and the center of the scale plate 110 is located on the straight line C on the Y axis negative direction side with respect to the transmission unit 122B.

  The light receiving element 123 is a light receiving element for an incremental pattern, and for example, a photodiode (Photo Diode: PD) can be used. The light receiving elements 123 that generate the A-phase and B-phase sine waves are arranged in a fan shape at an equal pitch along the rotation direction of the scale plate 110. The pitch of the light receiving elements 123 is the distance between the centers in the rotation direction of the scale plate 110 between the adjacent light receiving elements 123.

  In FIG. 2A, for convenience of explanation, the numbers 1 to 7 are sequentially assigned to the seven reflecting portions 111 located on the left side of the straight line C in the counterclockwise direction. Further, the numbers 1 to 7 are sequentially assigned to the seven light receiving elements 123 positioned on the left side of the straight line C in the counterclockwise direction. The edge in the circumferential direction of the first reflecting portion 111 overlaps the straight line C as shown in FIG.

  In this state, the reflected light emitted from the Lambertian LED 121 and reflected by the first to seventh reflecting portions 111 is received by the first to seventh light receiving elements 123, respectively. The light emitted from the Lambertian LED 121 is similarly received by the seven light receiving elements 123 symmetrically with respect to the YZ plane passing through the straight line C.

  The light receiving element 124 is a light receiving element for an absolute pattern, and for example, a photodiode (PD) can be used. There are nine light receiving elements 124, which are arranged in a fan shape along the rotation direction of the scale plate 110. In FIG. 2A, numbers 1 to 9 are assigned clockwise from the leftmost light receiving element 124. The fifth light receiving element 124 is arranged such that the center of the width in the rotation direction of the scale plate 110 is positioned on the straight line C.

  The reflected light emitted from the Lambertian LED 121 and reflected by the reflecting portion 112 is received by the first to ninth light receiving elements 124. Nine light receiving elements 124 provide a value for a 9-bit absolute pattern.

  As shown in FIG. 4, the wall portion 130 is attached to the Z-axis positive direction side of the base portion 120 </ b> A of the optical module 120. The base portion 120A is a rectangular substrate in plan view, and the LED 121 and the light receiving elements 123 and 124 are disposed on the surface on the Z axis positive direction side.

  The wall portion 130 is a rectangular ring-shaped rectangular tube member in plan view having the same dimensions as the four sides of the base portion 120A, a rectangular opening portion 130A on the Z-axis negative direction side, and a rectangular shape on the Z-axis positive direction side. And an opening 130B having a shape. The wall 130 is made of, for example, a resin, and may be formed by stacking a plurality of layers of glass epoxy resins for a wiring board patterned in a rectangular ring shape.

  The opening 130A is joined to the base 120A. The wall 130 surrounds (encloses) the LED 121 and the light receiving elements 123 and 124, and the mask plate 131 is joined to the opening 130B. The wall 130, the base 120A, and the mask plate 131 may be joined using, for example, an adhesive, or may be joined by other methods.

  The mask plate 131 is a rectangular and plate-like member joined to the four sides of the opening 130 </ b> B, and may be made of an insulating material such as a resin or a metal material. The mask plate 131 has fan-shaped slits 131A and 131B in plan view. The mask plate 131 is configured not to transmit light in portions other than the slits 131A and 131B.

  The slit 131 </ b> A is a fan-shaped opening corresponding to the reflecting portion 111 and the light receiving element 123 so that the reflected light emitted from the LED 121 and reflected by the reflecting portion 111 does not block all the optical paths that reach the light receiving element 123. The reflecting portion 111 here is a reflecting portion 111 that reflects light to the light receiving element 123 by rotation of the scale plate 110 among the plurality of reflecting portions 111 provided over the circumferential direction of the scale plate 110. The slit 131 </ b> A is an elongated slit having an arcuate longitudinal direction along the rotation direction of the scale plate 110.

  Similarly, the slit 131B has a fan shape corresponding to the reflecting portion 112 and the light receiving element 124 so that the reflected light emitted from the LED 121 and reflected by the reflecting portion 112 does not block all the optical paths that reach the light receiving element 124. Is the opening. The slit 131 </ b> B is an elongated slit having an arcuate longitudinal direction along the rotation direction of the scale plate 110.

  When the wall portion 130 as described above is attached to the Z-axis positive direction side of the base portion 120A of the optical module 120 and the mask plate 131 is attached to the Z-axis positive direction side of the wall portion 130, the light is emitted from the LED 121, and the reflection portion 111 and All the optical paths through which the reflected light reflected by 112 reaches the light receiving elements 123 and 124 pass through the slits 131A and 131B.

  For this reason, even if the wall 130 and the mask plate 131 are attached to the optical module 120, the reflective encoder 100 can detect the rotation angle of the motor 50 based on information obtained by the light receiving elements 123 and 124.

  In addition, since the notch portion 141 and the opening portion 142 are provided in the encoder cover 140, light outside the encoder cover 140 may enter the inside of the encoder cover 140. May invade.

  In such a case, since the optical module 120 is covered with the wall 130 and the mask plate 131, intrusion of light and dust from the outside of the wall 130 and the mask plate 131 can be suppressed.

  That is, erroneous detection and malfunction of the optical module 120 due to intrusion of light or dust can be suppressed, and the reliability of the reflective encoder 100 can be improved.

  Therefore, according to the embodiment, a highly reliable reflective encoder 100 can be provided.

  More specifically, in the reflective encoder 100 that requires an opening for engaging a jig that holds the encoder cover 140 when the positions of the substrate 101, the encoder cover 140, and the motor 50 are aligned, The erroneous detection and malfunction of the optical module 120 due to the intrusion of dust can be suppressed, and the reliability of the reflective encoder 100 can be improved.

  Here, the height of the wall portion 130 is the distance in the Z-axis direction between the substrate 101 and the scale plate 110 and all the optical paths between the LED 121, the reflection portions 111 and 112, and the light receiving elements 123 and 124. Considering this, an appropriate value may be set. For example, when the thickness of the base portion 120A in the Z-axis direction is 0.25 mm and the distance in the Z-axis direction between the substrate 101 and the scale plate 110 is 3.6 mm, the thickness is set to 2 mm as an example. That's fine.

  In the above, the form in which the wall portion 130 is rectangular in a plan view has been described. However, the shape of the wall portion 130 is not limited to the shape described above, and may be a shape other than a rectangular shape such as an annular shape. Good.

  In the above description, the scale plate 110 has the reflective portion 111 for the incremental pattern and the reflective portion 112 for the absolute pattern. However, when the reflective portion 112 is not provided, the wall portion 130 is provided. May not have the slit 131B. The opening shape of the slits 131A and 131B may be set to an appropriate shape according to the number and size of the light receiving elements 123 and 124.

  In the above description, the encoder cover 140 has the notch 141 and the opening 142 having the above-described configuration. However, the encoder cover 140 may be either the notch 141 or the opening 142. The structure of the notch part 141 and the opening part 142 is not limited to the above-mentioned structure. The encoder cover 140 may be configured to have an opening in the state where the encoder cover 140 is assembled with the substrate 101 and the housing 50A of the motor 50.

  In the above description, the notch 141 and the opening 142 of the encoder cover 140 are provided for engaging the jig. However, the present invention is not limited to the jig. For example, it may be a notch or an opening for passing wiring connected to the optical module 120.

  In the above description, the case where the casing 50A of the motor 50 is attached to the Z axis positive direction side of the encoder cover 140 has been described. However, instead of the casing 50A, a board is attached and the board 50A is attached to the Z axis positive direction side of the board. The structure to which the motor 50 is attached may be sufficient.

  In the above description, the encoder cover 140 has a cylindrical shape. However, the shape is not limited to the cylindrical shape, and may be another shape such as a rectangular tube shape.

  In the above description, the reflective portions 111 and 112 are provided on the surface of the scale plate 110 on the negative Z-axis direction. However, the reflective portions 111 and 112 are provided on the surface of the scale plate 110 on the positive Z-axis direction. In this case, a substrate or the like is provided on the Z-axis positive direction side of the scale plate 110, and the optical module 120 is provided on the Z-axis negative direction side of the substrate so as to face the reflecting portions 111 and 112. You can do it.

  In the above description, the reflective encoder 100 is a rotary reflective encoder. However, the reflective encoder 100 may be a linear reflective encoder.

  The reflective encoder according to the exemplary embodiment of the present invention has been described above, but the present invention is not limited to the specifically disclosed embodiment, and does not depart from the scope of the claims. Various modifications and changes are possible.

DESCRIPTION OF SYMBOLS 50 Motor 50A Case 100 Reflective encoder 110 Scale board 111, 112 Reflection part 120 Optical module 120A Base part 121 LED
123, 124 Light receiving element 130 Wall 131 Mask plate 131A, 131B Slit 140 Encoder cover 141 Notch 142 Opening

Claims (3)

A scale plate having a plurality of patterns provided on the first surface;
A substrate disposed opposite to the first surface of the scale plate;
A light emitting unit disposed on a surface facing the first surface of the substrate and irradiating the scale plate with irradiation light;
A plurality of light receiving elements disposed on the opposing surface of the substrate and receiving reflected light reflected by the pattern of the scale plate;
A cover having a cylindrical side wall surrounding the scale plate, the light emitting unit, and the light receiving element, the cover having at least one opening or notch in the side wall; and
A reflective encoder, comprising: an annular wall portion disposed on the opposing surface of the substrate and surrounding the light emitting portion and the plurality of light receiving elements.   2. The mask plate according to claim 1, further comprising: a mask plate that covers an opening of the wall portion on the scale plate side, and has a slit corresponding to an optical path from the light emitting portion to the light receiving element through the pattern. Reflective encoder.   The reflective encoder according to claim 2, wherein the slit is a fan-shaped slit corresponding to the optical path.