JP2008256641A - Planar light guide disk, optical encoder and tape feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tape feeder capable of controlling the feeding amount of carrier tape with high precision and high degrees of freedom of design, an optical encoder combining the space-saving nature with the high detection precision, and a planar light guide disk guiding light in the radial directions. <P>SOLUTION: The optical encoder includes: a planar light guide disk 15 guiding incident light from a first plane side to a space between a first plane and a second plane to reflect it to the first plane side; a rotation slit plate 14, which is prepared at the first plane side of the planar light guide disk 15 so as to share a center axis, including a slit train 14a with different pattern for every central angle; a light-emitting element 11a for entering light into the planar light guide disk 15; a light receiving element 11b for receiving the reflected light transmitting through a slit 14b of the rotation slit plate 14; and a sprocket 1, which rotates synchronously with the rotation slit plate 14, for conveying career tapes. The light receiving element 11b detects the rotation angle of the sprocket 1 from the pattern of reflected light received by the light receiving element 11b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface light guide disk that guides light in a radial direction, an optical encoder that includes the surface light guide disk, and a tape feeder that includes the surface light guide disk.

The tape feeder has a function of supplying mounting components stored in a carrier tape to a pickup position by a mounting head. The tape feeder is equipped with a sprocket that engages with a feed hole provided in the carrier tape, and the carrier tape is fed by the rotation of the sprocket so that the stored parts are sequentially supplied to the pickup position. It has become. In order to accurately supply the parts depending on the pickup position, it is necessary to strictly control the feed amount of the carrier tape. As a tape feeder that realizes this, the rotating disk and sprocket are connected by an endless belt, and the rotation angle of the rotating disk is Has been proposed in which the feed amount of the carrier tape is controlled by detecting this with an encoder (Patent Document 1).
JP-A-10-139272

  However, since the rotating disk and the sprocket are connected by an endless belt, there is a problem in that the layout inside the casing with a limited tape feeder is limited, and the degree of freedom in design is reduced. Further, the rigidity required to withstand the tension of the endless belt is required, and there is a problem that the weight of the tape feeder increases in order to ensure rigidity in addition to the weight of the endless belt itself. Furthermore, the endless belt responsible for rotation transmission causes a phase difference between the rotation angle of the sprocket and the rotation angle of the rotating disk, and there is a problem in the reliability of the detection result.

  Therefore, the present invention provides a tape feeder with a high degree of design freedom and a high precision control of the carrier tape feed amount, an optical encoder having both space saving and high detection accuracy, and a surface guide for guiding light in the radial direction. An object is to provide an optical disk.

  The surface light guide disk according to claim 1 has a first surface and a second surface facing each other, and guides light incident from the first surface side between the first surface and the second surface. A surface light guide disk that reflects toward one surface, and is provided in an annular shape at least on the outer periphery or the inner periphery with the central axis of the disk as the center, and the light incident from the first surface side has a diameter A first reflecting portion that reflects in the direction, and a second reflecting portion that is provided in plural on a concentric circle centered on the central axis of the disc and reflects light reflected by the first reflecting portion to the first surface side. .

  The surface light guide disk according to claim 2 is the surface light guide disk according to claim 1, and is incident on an area defined by a predetermined central angle of the disk and the first surface and the surface light disk. A third reflecting portion that reflects light guided between the second surfaces into the region is provided.

  The surface light guide disk according to claim 3 is the surface light guide disk according to claim 1 or 2, wherein the disk is one prism body, and the first reflecting portion is the first reflection part. A taper surface that expands from the second surface toward the first surface continuously from the outer periphery of each of the surface and the second surface, and the second reflecting portion extends from the second surface to the first surface. A tapered surface is formed on the second surface so as to reduce the diameter toward the surface.

  The surface light guide disk according to claim 4 is the surface light guide disk according to claim 2 or 3, wherein the third reflecting portion is provided on the first surface and the second surface of the disk. It is composed of inclined surfaces of a plurality of triangular grooves formed radially at a predetermined central angle with the central axis of the disk as the center.

  The optical encoder according to claim 5 has a first surface and a second surface that face each other, and guides light incident from the first surface side between the first surface and the second surface. And a light-shielding disk having a light-transmitting part and a light-shielding part having different patterns for each central angle. The light-shielding disk includes a light-emitting part that makes light incident on the surface light-guiding disk and a light-receiving part that receives reflected light that has passed through the light-transmitting part of the light-shielding disk. The rotation angle of is detected.

  The tape feeder according to claim 6 has a first surface and a second surface that face each other, guides light incident from the first surface side between the first surface and the second surface, and the first surface. And a light-shielding disk having a light-transmitting part and a light-shielding part having different patterns for each central angle. A light-emitting part that makes light incident on the surface light guide disk, a light-receiving part that receives reflected light that has passed through the light-transmitting part of the light-shielding disk, and a light-shielding disk An optical encoder that detects the rotation angle and a carrier tape transport sprocket that rotates in synchronization with the light-shielding disk are provided.

  According to the surface light guide disk of the present invention, it is possible to realize space saving and high detection accuracy in the optical encoder, and high precision control of the design freedom and the feed amount of the carrier tape in the tape feeder. Can be realized.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a state where an optical encoder is mounted on a sprocket built in a tape feeder according to an embodiment of the present invention, and FIG. 2 is an exploded view of the sprocket and optical encoder according to the embodiment of the present invention. FIG. 3 is a radial sectional view of the surface light guide disk according to the embodiment of the present invention (AA sectional view shown in FIG. 2), and FIG. 4 is a perspective view of the present invention. It is sectional drawing (BB sectional drawing shown in FIG. 2) of the circumferential direction of the surface light guide disc of embodiment.

  In FIG. 1, a sprocket 1 is built in a tape feeder with a pin 2 provided on the outer periphery engaged with a carrier tape 3. The tape feeder performs a feeding operation of the carrier tape 3 engaged with the pin 2 by transmitting a rotational driving force around the central axis a to the sprocket 1, and sequentially supplies the components stored in the carrier tape 3 to the pickup position. .

  In FIG. 2, the optical encoder 10 includes a photosensor 11, a prism 12, a fixed slit plate 13, a rotary slit plate 14, and a surface light guide disc 15. The rotating slit plate 14 and the surface light guide disc 15 are attached to the sprocket 1 in this order, and are configured to rotate in synchronization with the rotating sprocket 1 around the central axis a. On the other hand, the photosensor 11, the prism 12, and the fixed slit plate 13 are fixed to the tape feeder 4 so that their positions with respect to the central axis a are not changed. The sprocket 1 is made of a metal material such as stainless steel, and the surface 1a of the sprocket 1 functions as a reflecting surface that reflects light, but a reflecting sheet formed of a material having higher reflectivity is provided as a reflecting surface. Also good.

The photosensor 11 is a reflection type photosensor including six light receiving elements 11b in an array serving as a light receiving unit with respect to one light emitting element 11a serving as a light emitting unit, and reflects reflected light of light emitted from the light emitting element 11a. It is received and detected by the light receiving element 11b. The photosensor 11 is arranged on the side facing the surface light guide disk 15 with the rotating slit plate 14 interposed therebetween so that the light emitting direction and the light receiving direction are orthogonal to the central axis a. The prism 12 includes one light-emitting prism 12a that changes the traveling direction of light emitted from the light-emitting element 11a by 90 degrees so as to be in the same direction as the central axis a and is incident on the surface light-guiding disk 15, and a surface light-guide. It consists of six light receiving prisms 12b that change the traveling direction of the light reflected by the disk 15 by 90 degrees and cause each light receiving element 11b to receive light.

  The rotating slit plate 14 allows a part of the light reflected by the surface light guide disk 15 to pass through the slits such as a plurality of slit groups 14a formed on the same angle with the central axis a as the center, and blocks the others. It is a shading disk. In each slit group 14a, a light transmitting portion and a light shielding portion are arranged in the radial direction, and a combination pattern of the light transmitting portion and the light shielding portion is different among all the slit groups 14a. The translucent part is formed by slits 14b established in the rotary slit plate 14. By providing a difference in the number and position of the slits 14b, the combination pattern of the translucent part and the light-shielding part is changed for each slit group 14a. Yes. Therefore, the pattern of the reflected light that passes through the slit 14b changes for each rotation angle of the rotary slit plate 14, and the combination pattern of the light receiving elements 11b that receive the reflected light differs for each rotation angle of the rotary slit plate 14. The rotation angle of the rotary slit plate 14, that is, the rotation angle of the sprocket 1 can be detected by grasping the light reception state in each light receiving element 11b.

  An entrance slit 14c corresponding to each slit group 14a is formed on the outer edge of the rotary slit plate 14, and the light that passes through the light emitting prism 12a from the light emitting element 11a is transmitted through the surface light guide circle regardless of the rotation angle of the rotary slit plate 14. It is a translucent part for making it incident on the plate 15.

  The fixed slit plate 13 is disposed between the light-emitting prism 12 a and the light-receiving prism 12 b and the rotary slit plate 14. The incident slit 13 a for allowing light to enter the surface light guide disk 15 and the surface light guide disk 15 A reflection slit group 13b for allowing the reflected light to pass therethrough is formed. The reflection slit group 13b is composed of slits formed at six locations corresponding to the number of light receiving elements 11b. The incident slit 13a has a role of reliably allowing the light having passed through the light emitting prism 12a to be incident on the incident slit 14b of the rotary slit plate 14 and blocking the incident to the adjacent slit group 14a. The reflective slit group 13b is a slit group. The reflected light that has passed through 14a is reliably incident on the corresponding light receiving prism 12b, and prevents incident on the non-corresponding light receiving prism 12b.

  The surface light guide disk 15 is a prism body that reflects the light incident through the light emitting prism 12a toward the light receiving prism 12b, and has high light transmittance such as polyacetal (POM) or methyl methacrylate resin (PMMA). It is formed in a disc shape having substantially the same diameter as that of the rotary slit plate 14 using resin as a raw material.

  In FIG. 3, the surface light-guiding disk 15 has a first surface 20 and a second surface 21 that are parallel to each other, and a tapered surface 22 in which each outer periphery expands from the second surface 21 toward the first surface 20. It is continuous with. In addition, the 1st surface 20 is a side attached to the rotation slit board 14, and the 2nd surface 21 is a side attached to the sprocket 1 (refer FIG. 1). A plurality of tapered surfaces 23 are formed on the second surface 21 at substantially the same intervals so as to reduce the diameter from the second surface 21 toward the first surface 20 on a concentric circle with the central axis a as the center.

Since these tapered surfaces 23 and the tapered surfaces 22 provided on the outer periphery are opposed to each other, the light incident from the first surface 20 side toward the tapered surface 22 is diffusely reflected in the radial direction, and a plurality of tapered surfaces 23 are provided. The direction of travel is changed toward the inner peripheral side where is formed, and light is directly incident on the tapered surface 23 positioned on the near side, and the first surface 20 reflects the tapered surface 23 positioned on the inner peripheral side. Incident light. Light incident on each tapered surface 23 is reflected toward the first surface 20. Thus, in the surface light guide disk 15, the tapered surface 22 functions as a first reflecting portion that diffuses and reflects light incident from the first surface 20 side in the radial direction, and the tapered surface 23 is the first reflecting portion. It functions as a second reflecting part that reflects light diffusely reflected by a certain tapered surface 22 toward the first surface 20, and guides light incident from the first surface 20 side between the first surface 20 and the second surface 21. It has the function of shining and reflecting to the first surface side.

  In FIG. 2, a plurality of triangular grooves 24 are formed radially on the surface light guide disk 15 about the central axis a, and the surface light guide disk 15 is divided into a plurality of fan-shaped regions by the adjacent triangular grooves 24. It is partitioned. In FIG. 4, the triangular groove 24 is formed to face the first surface 20 and the second surface 21, and has two inclined surfaces 24a and 24b, respectively. The opposing inclined surfaces 24a and 24b of the adjacent triangular grooves 24 on the first surface 20 side are inclined so as to expand toward the second surface 21 side, and the adjacent triangular grooves 24 on the second surface 21 side The opposing inclined surfaces 24a and 24b are inclined so as to expand toward the first surface 20 side. For example, when light in a certain sector region 15a travels in the direction of arrow a, it is reflected in the direction of arrow b by the inclined surface 24b, so that diffusion to the adjacent sector region 15b is prevented, and light is transmitted in the direction of arrow c. When traveling in the direction, since the light is reflected in the direction of the arrow d by the inclined surface 24a, diffusion to the adjacent fan-shaped region 15c is prevented. As described above, the inclined surfaces 24a and 24b function as a third reflecting portion that reflects light in an arbitrary fan-shaped region into the region, and has an effect of suppressing diffusion outside the region. Therefore, as shown in FIG. 2, the light incident in a certain sector area is guided toward the inner circumference side in the area while suppressing the diffusion to the adjacent sector area. Reflected to the surface 20 side with a sufficient amount of light.

  The optical encoder 10 includes the photosensor 11, the prism 12, the fixed slit plate 13, the rotary slit plate 14, and the surface light guide disc 15 described above, and can be arranged on one side of the rotation angle detection target. It is space-saving. Further, since the rotary slit plate 14 and the surface light guide disc 15 are directly attached to the rotation angle detection target, the detection accuracy is significantly improved as compared with the case where the rotary slit plate 14 and the surface light guide disc 15 are attached via other members. This optical encoder 10 is suitable for a tape feeder that is becoming thinner and lighter with high accuracy in terms of space saving and high detection accuracy, and the rotation angle of a sprocket built in the tape feeder is accurately determined. It is possible to control the feeding amount of the carrier tape with high accuracy.

  In the above-described embodiment, the number of the light receiving elements 11b and the number of the light receiving prisms 12b constituting the light receiving portion, and the total number of the light transmitting portions and the light shielding portions formed in each slit group 14a are set to six. However, the number of the light receiving elements 11b and the light receiving prisms 12b depends on the total number of the light transmitting portions and the light shielding portions formed in each slit group 14a, and the pattern of the reflected light is changed to the rotation angle. As long as it can be changed every time, the total number of the light transmitting portions and the light shielding portions may be any number. The light emitted from the light emitting element 11a serving as the light emitting portion is incident on the tapered surface 22 serving as the outer periphery of the surface light guide disk 15 and then guided toward the inner peripheral side. The light may be incident on the circumferential side and guided toward the outer circumferential side. In this case, the taper surface 22 that is the first reflection portion and the taper surface 23 that is the second reflection portion are opposite to the above-described directions.

  According to the present invention, it is possible to realize space saving and high detection accuracy in an optical encoder, and it is possible to realize a high degree of design freedom and high accuracy control of the feed amount of a carrier tape in a tape feeder. It is useful in the mounting field where high mounting accuracy is required.

The perspective view which shows the state by which the optical encoder was mounted | worn with the sprocket built in the tape feeder of embodiment of this invention The perspective view which shows the state which decomposed | disassembled the sprocket and optical encoder of embodiment of this invention Sectional drawing of the radial direction of the surface light guide disc of embodiment of this invention (AA sectional drawing shown in FIG. 2) Sectional drawing of the circumferential direction of the surface light guide disk of embodiment of this invention (BB sectional drawing shown in FIG. 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sprocket 10 Optical encoder 11a Light emitting element 11b Light receiving element 14 Rotating slit plate 15 Surface light guide disk 20 First surface 21 Second surface 22, 23 Tapered surface 24 Triangular groove 24a, 24b Inclined surface

Claims (6)

A surface light guide disk that has a first surface and a second surface facing each other, guides light incident from the first surface side between the first surface and the second surface, and reflects the light to the first surface side. And
A first reflecting portion that is annularly provided at least near the outer periphery or the inner periphery around the central axis of the disc and reflects light incident from the first surface side in the radial direction;
A planar light guide disc provided with a second reflecting portion provided on a plurality of concentric circles centered on the central axis of the disc and reflecting the light reflected by the first reflecting portion to the first surface side.   3. A third reflection unit that includes a third reflection unit configured to reflect light, which is incident on an area defined by a predetermined central angle of the disk and guided between the first surface and the second surface, into the area. The surface light guide disk according to 1. The disc is a prism body;
The first reflecting portion is configured by a tapered surface that expands from the second surface toward the first surface continuously with the outer circumferences of the first surface and the second surface,
3. The surface light guiding circle according to claim 1, wherein the second reflecting portion includes a tapered surface formed on the second surface so as to reduce the diameter from the second surface toward the first surface. Board.   The third reflecting portion is composed of inclined surfaces of a plurality of triangular grooves that are radially formed on the first surface and the second surface of the disc at a predetermined central angle centered on the central axis of the disc. The surface light guide disk according to claim 2 or 3. A surface light guide disk having a first surface and a second surface facing each other, guiding light incident from the first surface side between the first surface and the second surface and reflecting the light to the first surface side;
A light-shielding disk having the same central axis on the first surface side of the surface light-guiding disk and having different patterns of light-transmitting parts and light-shielding parts for each central angle;
A light-emitting unit that makes light incident on the surface light guide disc;
A light receiving portion that receives the reflected light that has passed through the light transmitting portion of the light shielding disc,
An optical encoder that detects a rotation angle of a light shielding disk based on a pattern of reflected light received by a light receiving unit. A surface light guide disk that has a first surface and a second surface facing each other, guides light incident from the first surface side between the first surface and the second surface, and reflects the light to the first surface side; ,
A light-shielding disk having the same central axis on the first surface side of the surface light-guiding disk and having different patterns of light-transmitting parts and light-shielding parts for each central angle;
A light-emitting unit that makes light incident on the surface light guide disc;
A light receiving portion that receives reflected light that has passed through the light transmitting portion of the light shielding disc;
An optical encoder that detects the rotation angle of the light-shielding disk based on the pattern of reflected light received by the light-receiving unit;
Tape feeder equipped with a carrier tape sprocket that rotates in synchronization with the light-shielding disk.

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