JP2007078387A - Optical rotary encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical rotary encoder capable of making it easier to fix the light-emitting element and to adjust the position of the same. <P>SOLUTION: The optical rotary encoder is provided with the light-emitting element 8 stored in a can 8a provided with a projection 8b for positioning, the cylindrical light-emitting element holder 10 for storing the can 8a and the lens 9, and the power source circuit substrate 7 for mounting the light-emitting element 8, for making the positional adjustment of the light-emitting element 8 and the lens 9 possible. The recess 10a for engaging with the projection 8b of the can 8a at the end part of one side of the light-emitting element holder 10, the projection 10b on the other end face and the step part 10c for resting a lens are respectively provided, and further the notch for engaging with the projection 10b of the light-emitting element 8 and the light-emitting element holder 10 on the power source substrate. Thereby, the positional adjustment is made easy because the mounting operation of the light-emitting element 8 becomes easy to reduce the dispersion of the positional deviation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mounting structure that facilitates an optical axis adjustment operation between light emitting and receiving elements.

  Conventionally, in an optical rotary encoder, a slit pattern of a rotary code plate that is a part of a rotating unit is aligned with a slit pattern of a fixed code plate that is fixed to a light receiving element that is a part of a fixed unit, and then light emission is performed. The position of the light emitting element is adjusted by using an electrical signal so that the light amount of the element becomes equal to or more than a predetermined value on the light receiving element side.

  The light emitting element and the light receiving element are respectively fixed so as to face predetermined positions of the encoder frame via circuit boards, and the slit pattern of the rotary code plate rotates and moves between them. It was necessary to correct the position and tilt according to the situation.

  In addition, the conventional light emitting element has an integrated configuration in which the light emitting unit and the lens unit are attached via a can, and the position and the inclination between the light emitting unit and the lens unit are greatly varied, and the optical axis is not stable.

On the other hand, an assembly method using a prism has been proposed for the alignment of the slit patterns of the rotary code plate and the fixed code plate (see, for example, Patent Document 1).
JP-A-10-206191

  The problem to be solved is that it is difficult to align the optical axis between the light emitting and receiving elements. The alignment of the rotating code plate and the fixed code plate can be handled by an assembly method using a prism, but the alignment of the optical axis between the light receiving and emitting elements is greatly affected by variations in the assembly accuracy of the light emitting elements. Was not easy.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems, and to provide an optical rotary encoder that facilitates an adjustment operation of an optical axis between light emitting and receiving elements and has a stable positional accuracy.

  In order to solve the above-described problems, the present invention separately provides a rotating part having a rotary code plate and a fixing part that fixes a light-emitting element assembly and a circuit board to which a light-receiving element is attached at a predetermined position facing the encoder frame. In the constructed rotary encoder, the light emitting element assembly houses a light emitting element housed in a can having a positioning projection, a lens that collimates light emitted from the light emitting element, and the light emitting element and the lens. A cylindrical light-emitting element holder, a step portion for storing the light-emitting element and the lens in parallel at an inner peripheral end portion of the light-emitting element holder, and a concave portion that engages a protruding portion of the can at one end surface portion Further, a convex portion is provided on the opposite end surface portion, and a key hole portion that engages with the convex portion is provided on the circuit board to facilitate optical axis adjustment.

According to the optical rotary encoder of the present invention, the light emitting element and the lens are configured separately, and the optical axis is stabilized because the light emitting element and the lens are accommodated in parallel by the step portion of the light emitting element holder. On the other hand, the positioning of the light emitting element and the light emitting element assembly and the attaching operation are facilitated by the engagement of the can protrusion and the concave portion of the light emitting element holder, and the convex portion of the lens light emitting element holder and the key hole of the circuit board.

  In addition, since the light emitting element holder acts as a spacer, the gap variation between the light emitting element and the light receiving element can be reduced, and since the light emitting element holder acts as a holding function in the radial direction, the inclination of the light emitting element can be prevented.

  As described above, an optical rotary encoder can be obtained in which variations in the position and inclination of the optical axis between the light emitting and receiving elements are reduced and the optical axis can be easily adjusted.

  The light emitting element assembly includes a light emitting element housed in a can having a positioning protrusion, a lens that collimates light emitted from the light emitting element, a light emitting element and a cylindrical light emitting element holder that houses the lens. An inner peripheral end portion of the light emitting element holder, a step portion for storing the light emitting element and the lens in parallel, a concave portion that engages with the protruding portion of the can on one end surface portion, and an opposite end surface portion Protruding portions are provided, and the circuit board is provided with a keyhole portion that engages with the protruding portions, thereby reducing variations in the position and inclination of the optical axis between the light receiving and emitting elements, and facilitating optical axis adjustment. .

  In FIG. 1, the rotating part of the optical rotary encoder is composed of a rotary code plate 1 and an encoder boss 2, and is fixed to the motor shaft 3 after centering and fixing.

  The fixing part is an analog signal processing circuit board 4 on which a light receiving element 5 or the like with a fixed code plate 6 is mounted, and a power circuit board on which a light emitting element assembly including a light emitting element 8, a lens 9 and a light emitting element holder 10 is mounted. 7 and the encoder frame 11, and the analog signal processing circuit 4 and the power supply circuit board 7 are fixed to a predetermined position of the encoder frame 11.

  The light emitting element 8 is housed in a can 8a having a positioning protrusion 8b and is a commercial product. The outer periphery of the can 8a is housed in a light-emitting element holder 10 made of a cylindrical synthetic resin. A concave portion 10a that engages with the protruding portion 8b of the can 8a is formed on one end surface of the light-emitting element holder 10, and the opposite end surface In addition to the convex portion 10b, a step portion 10c is provided for the lens 9 to be accommodated in parallel with the light emitting element 8 (see FIGS. 2 and 3).

  On the other hand, the power supply circuit board 7 is provided with a keyhole portion 7a that engages with the light emitting element 8 body and the convex portion 10b of the light emitting element holder 10 (see FIG. 4).

  First, the protrusion 8b and the recess 10a are engaged while the outer periphery of the can 8a of the light emitting element 8 is held by the inner periphery of the light emitting element holder 10. Next, in order to house the lens 9 in parallel with the light emitting element 8, it is inserted into the step portion 10c of the light emitting element holder 10 to form a light emitting element assembly.

  Next, the convex part 10 b of the light emitting element holder 10 and the key hole part 7 a of the power circuit board 7 are engaged, and the lead terminal of the light emitting element 10 is soldered and fixed to the wiring pattern of the power circuit board 7. Thereafter, the encoder frame 11 is fixed at a predetermined position.

  Since the light emitting element holder 10 acts as a spacer and a holding function, the distance variation from the light emitting element 8 to the light receiving element 5 is reduced.

In addition, since the light emitting element 8 and the lens 9 can be accommodated in parallel, the optical axis can be freely controlled and the optical axis can be more stable than a conventional light emitting element assembly in which the light emitting part and the lens part are attached via a can. Can be

  In addition, since the variation in the inclination of the light emitting element 8 attached to the power circuit board 7 can be reduced, an optical rotary encoder that facilitates the position adjusting operation with respect to the light receiving element 5 can be obtained.

  In addition, even if it changes the shape of the convex part of a light emitting element holder into a recessed part, it can implement similarly. In that case, the keyhole portion of the power circuit board may be changed to a convex shape that engages with the concave portion of the light emitting element holder.

  In addition, by providing depressions at the corners of the step of the light emitting element holder 10, the optical axis can be further stabilized by further improving the accuracy of parallel storage of the light emitting element 8 and the lens 9.

  The optical rotary encoder of the present invention is useful for a servo motor or the like because the positional accuracy is stable.

Sectional drawing of the principal part in the optical rotary encoder of this invention The fragmentary sectional view of the light emitting element assembly in Example 1 of the present invention The bottom view of the light emitting element assembly in Example 1 of this invention The top view of the circuit board in Example 1 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation code board 2 Encoder boss 3 Motor shaft 4 Analog signal processing circuit board (circuit board)
5 Light receiving element 6 Fixed code plate 7 Power circuit board (circuit board)
7a Keyhole part 8 Light emitting element 8a Can 8b Protruding part 9 Lens 10 Light emitting element holder 10a Concave part 10b Convex part 10c Step part 11 Encoder frame

Claims (1)

In the rotary encoder comprising a rotating part provided with a rotary code plate and a fixing part in which a light-emitting element assembly and a circuit board to which a light-receiving element is attached are fixed at predetermined positions opposed to the encoder frame, the light-emitting element assembly comprises: A light emitting element housed in a can having a positioning protrusion, a lens that collimates light emitted from the light emitting element, and a light emitting element holder that houses the light emitting element and the lens, A step portion for storing the light emitting element and the lens in parallel is provided at an inner peripheral end portion of the light emitting element holder, a concave portion that engages with the protruding portion of the can at one end surface portion, and a convex portion at the opposite end surface portion. Optical rotary encoders each provided and provided with a keyhole portion that engages with the convex portion on the circuit board to facilitate optical axis adjustment.