JP2008134122A - Optical encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical encoder capable of preventing grease from leaking to the photointerrupter side through the periphery of a shielding plate formed on the base end side of an operation shaft. <P>SOLUTION: This encoder has a grease protection wall 4e elongated from the inside of the bottom surface of a case member 4, and formed to cover the outside of the photointerrupter 2; and a rib part 3a formed on the whole circumference of an outer circumferential surface on the base end side of the operation shaft 3 to be positioned on a groove part 4f formed on the bottom surface between the inner peripheral surface of the case member 4 and the grease protection wall 4e. Grease 10a is applied onto at least a part between the inner peripheral surface of the case member 4 side of the groove part 4f and the outer peripheral surface of the rib part 3a, and the rib part 3a is allowed to abut slidably on the inner peripheral surface of the case member 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical encoder provided with a photo interrupter.

  Conventionally, for example, an optical encoder configured to detect a rotational displacement amount of an operation shaft with a photo interrupter is known (see, for example, Patent Document 1).

  By the way, as shown in FIGS. 3 and 4, the two photointerrupters 21 provided in the optical encoder 20 are integrally formed on a substrate 22 with a light emitting unit 23 and a light receiving unit 24 arranged to face each other. In addition, a plurality of light shielding plates 26 integrally formed on the base end side of the cylindrical operation shaft 25 are provided at regular intervals between the light emitting unit 23 and the light receiving unit 24. Detecting the rotational displacement amount of the operating shaft 25 in a non-contact manner based on a signal output from the light receiving unit 24 according to the situation where each light blocking plate 26 blocks the optical path between the light emitting unit 23 and the light receiving unit 24. Can do.

The two photo interrupters 21 are arranged in photo interrupter mounting portions 27 b and 27 c formed at the base end portion 27 a of the cylindrical case member 27. The inner cylindrical portion 27d extending from the base end portion 27a of the case member 27 is disposed so as to substantially contact the inner peripheral surface of the operation shaft 25 via the greases 28a and 28b, and the operation shaft 25 is a circle of the inner cylindrical portion 27d. It is configured to slide smoothly along the circumferential direction. A ring-shaped cover member 29 is fixed to the outer peripheral end of the case member 27 with an adhesive or the like so as to cover the proximal end side of the operation shaft 25.
Utility Model Registration No. 3018207

  Incidentally, in the conventional optical encoder 20 shown in FIG. 3, the operation shaft 25 and the inner cylinder portion 27d are arranged so that the operation shaft 25 slides smoothly along the peripheral surface of the inner cylinder portion 27d of the case member 27. Grease 28a, 28b is applied to the contact surface, and a step portion 27e is formed near the light shielding plate 26 of the inner cylindrical portion 27d so that the grease 28a does not leak to the photo interrupter 21 side.

  However, a gap is provided between the step portion 27e formed on the inner cylindrical portion 27d and the light shielding plate 26 so that the light shielding plate 26 does not contact the front end surface of the step portion 27e. If the operation shaft 25 is rotated for a long period of time, the grease 28a may leak from the gap between the stepped portion 27e and the light shielding plate 26 and adhere to the photo interrupter 21.

  If the grease 28a adheres to at least one of the light emitting unit 23 and the light receiving unit 24 of the photo interrupter 21, a normal signal is not output from the light receiving unit 24, and an accurate rotational displacement amount of the operation shaft 25 cannot be detected.

  Therefore, an object of the present invention is to provide an optical encoder that can prevent grease from leaking to the photo interrupter side through the vicinity of the light shielding plate formed on the base end side of the operation shaft.

  In order to achieve the above object, the present invention according to claim 1 is directed to an operation shaft made of a cylindrical resin material that is rotatably supported, and a circumferential surface on a proximal end side of the operation shaft along a circumferential direction. A plurality of light shielding plates formed at regular intervals, a photo interrupter configured such that a light emitting portion and a light receiving portion are opposed to each other with the light shielding plate interposed therebetween, and the light shielding plate of at least the operation shaft are formed. A case member made of a resin material provided so as to surround the outer peripheral surface on the base end side, and according to the situation where the light shielding plate blocks the optical path between the light emitting unit and the light receiving unit by the rotation of the operation shaft In the optical encoder for detecting the rotational displacement amount of the operation shaft based on the signal output from the light receiving unit, the grease is formed to extend from the inside of the bottom surface of the case member and cover the outside of the photo interrupter A protective wall, A rib portion formed on the entire circumference of the outer peripheral surface on the base end side of the operation shaft so as to be positioned in a groove portion formed on the bottom surface between the inner peripheral surface of the case member and the grease protective wall And applying grease to at least a part between the inner peripheral surface of the groove portion on the case member side and the outer peripheral surface of the rib portion, and sliding the rib portion on the inner peripheral surface of the case member. It is characterized by allowing it to contact freely.

  According to a second aspect of the present invention, the peripheral surface on the distal end side of the cover member disposed on the end surface opposite to the bottom surface of the case member is slidable on the outer peripheral surface of the operation shaft via grease. It is characterized by contacting.

  According to the optical encoder of the present invention according to claim 1, the grease protective wall formed so as to extend from the inner side of the bottom surface of the case member and cover the outer side of the photo interrupter, the inner peripheral surface of the case member, and the grease protective member Since it has a rib portion formed on the entire circumference of the outer peripheral surface on the base end side of the operation shaft so as to be positioned in the groove portion formed on the bottom surface between the wall and the case member side of the groove portion Since the grease applied between the inner peripheral surface of the rib and the outer peripheral surface of the rib portion is isolated by the grease protective wall, it is possible to reliably prevent the grease from leaking to the photo interrupter side.

  According to the optical encoder of the present invention according to claim 2, the peripheral surface on the front end side of the cover member disposed on the end surface opposite to the bottom surface of the case member is slid on the outer peripheral surface of the operation shaft via grease. By making it contact freely, the operation shaft can be rotated without backlash.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a schematic longitudinal sectional view showing an optical encoder according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the optical encoder according to the embodiment of the present invention.

  As shown in both drawings, the optical encoder 1 according to the embodiment of the present invention includes two photo interrupters 2, an operation shaft 3, a case member 4, and a cover member 5. The operation shaft 3, the case member 4, and the cover member 5 are formed of a resin material.

  The two photointerrupters 2 are formed integrally with a light emitting part 7 and a light receiving part 8 disposed on a substrate 6 so as to face each other, and are formed on the inner periphery of the base end side of the ring-shaped case member 4. It arrange | positions at the interrupter attaching part 4a, 4b. A plurality of light shielding plates 9 are integrally provided at regular intervals on the inner periphery on the proximal end side of the cylindrical operation shaft 3, and each light shielding plate 9 is formed along the inner periphery on the proximal end side of the case member 4. The concave light shielding plate placement portion 4c is located. A slit portion 4d for passing the light shielding plate 9 between the light emitting portion 7 and the light receiving portion 8 of the photo interrupter 2 is formed on the upper surface (surface opposite to the substrate 6) of the photo interrupter mounting portions 4a and 4b. .

  The case member 4 is integrally formed with a grease protection wall 4e formed so as to extend from the inside of the bottom surface in contact with the substrate 6 and cover the outside of the photo interrupter 2. In addition, a rib portion is provided on the entire circumference of the outer peripheral surface on the proximal end side of the operation shaft 3 so as to be positioned in a groove portion 4f formed on the bottom surface between the inner peripheral surface of the case member 4 and the grease protection wall 4e. 3a is integrally formed.

  Grease 10a is applied between the projected lower part of the inner peripheral surface of the groove 4f on the case member 4 side and the outer peripheral surface of the rib 3a, and the proximal end side of the operation shaft 3 is slidably in contact therewith. Further, the other end surface of the cover member 5 fixed to the distal end surface of the case member 4 is slidably in contact with the outer peripheral surface of the operation shaft 3 through the grease 10b so as to cover the outer periphery on the proximal end side of the case member 4. ing. Thereby, the operating shaft 3 can slide smoothly along the circumferential direction without rattling.

  The optical encoder 1 according to the embodiment of the present invention is configured as described above. When the operation shaft 3 is rotated, a light shielding plate 9 integrally formed on the proximal end side of the operation shaft 3 is provided. The optical path between the light emitting unit 7 and the light receiving unit 8 is intermittently blocked. Thereby, the rotational displacement amount of the operation shaft 3 can be detected in a non-contact manner based on the periodic signal output from the light receiving unit 8.

  Further, when the operation shaft 3 of the optical encoder 1 is rotated over a long period of time, it is applied between the projected lower portion of the inner peripheral surface of the groove 4f on the case member 4 side and the outer peripheral surface of the rib portion 3a. Even if the grease 10a leaks to the bottom side of the groove 4f, the photo interrupter 2 is covered and isolated by the grease protective wall 4e, so that it is possible to reliably prevent the grease 10a from leaking to the photo interrupter 2 side. . Therefore, a stable detection signal can be output from the light receiving unit 8 of the photo interrupter 2 over a long period of time.

1 is a schematic longitudinal sectional view showing an optical encoder according to an embodiment of the present invention. 1 is an exploded perspective view showing an optical encoder according to an embodiment of the present invention. The schematic longitudinal cross-sectional view which shows the optical encoder in a prior art example. The disassembled perspective view which shows the optical encoder in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical encoder 2 Photo interrupter 3 Operation shaft 3a Rib 4 Case member 4c Shading board arrangement | positioning part 4e Grease protection wall 4f Groove part 5 Cover member 6 Board | substrate 7 Light emission part 8 Light receiving part 9 Light shielding board 10a, 10b Grease

Claims (2)

An operation shaft made of a cylindrical resin material supported in a freely rotatable manner, a plurality of light shielding plates formed at regular intervals along the circumferential direction on the peripheral surface of the proximal end side of the operation shaft, and the light shielding plate It consists of a photo interrupter that is configured such that a light emitting portion and a light receiving portion are arranged opposite to each other, and a resin material that is provided so as to surround at least the outer peripheral surface on the base end side where the light shielding plate of the operation shaft is formed. A case member, and based on a signal output from the light receiving unit according to a situation where the light shielding plate blocks an optical path between the light emitting unit and the light receiving unit by rotation of the operation shaft. In the optical encoder that detects the amount of rotational displacement,
A grease protective wall that extends from the inside of the bottom surface of the case member and covers the outside of the photo interrupter;
A rib portion formed on the entire circumference of the outer peripheral surface on the proximal end side of the operation shaft so as to be positioned in a groove portion formed on the bottom surface between the inner peripheral surface of the case member and the grease protective wall And
Grease is applied to at least a part between the inner peripheral surface of the groove portion on the case member side and the outer peripheral surface of the rib portion, and the rib portion is slidably brought into contact with the inner peripheral surface of the case member. Let
An optical encoder characterized by that. The peripheral surface on the tip side of the cover member disposed on the end surface opposite to the bottom surface of the case member is slidably brought into contact with the outer peripheral surface of the operation shaft via grease.
The optical encoder according to claim 1.

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