JP4882840B2 - Surface light guide disk, optical encoder and tape feeder - Google Patents

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.

Accordingly, the present invention provides a surface light guide disk that can reflect light with a sufficient amount of light, an optical encoder that combines space saving and high detection accuracy, and a high degree of design freedom and a high carrier tape feed rate. and to provide a controllable tape feeder accuracy.

Plane light guide disc according to claim 1, having a first surface and a second surface facing the light guide light incident from the first surface side between the first surface and the second surface a plane light guide disc reflected on the first surface side to the surface light guide disc center axis the first provided annularly to one of at least near the outer periphery or the inner periphery toward the center of a first reflecting part for reflecting the light incident from the side in the radial direction, the light reflected plurally provided on a concentric circle around the central axis of the surface light guide disc at the first reflecting portion and the A second reflecting portion that reflects toward the first surface; and a plurality of triangular grooves that are radially formed on the first surface and the second surface at a predetermined central angle centered on a central axis of the surface light guide disk The light that enters the region defined by the predetermined central angle and is guided between the first surface and the second surface is reflected in the region. And a third reflecting unit.

The plane light guide disc according to claim 2 A plane light guide disc according to claim 1, the first reflecting section before SL is continuous with the outer periphery of each of the first surface and the second surface The second surface is configured by a tapered surface that increases in diameter from the second surface toward the first surface, and the second reflecting portion decreases in diameter from the second surface toward the first surface. It composed of a tapered surface formed on the surface.

The optical encoder according to claim 3, said plane light guide disc according to claim 1 or 2, similarly to arranged a central axis on the first surface side of the plane light guide disc center receiving and shielding disc having a light transmission part and the light shielding part of the different pattern for each corner, and a light-emitting portion incident light to the plane light guide disc, the reflected light transmitted through the light transmitting portion of the light shielding disc a light receiving unit that, the light receiving portion detects the rotation angle of the light shielding disk based on the pattern of the reflected light received.

Tape feeder according to claim 4, said plane light guide disc according to claim 1 or 2, similarly to arranged a central axis on the first surface side of the plane light guide disc, the central angle receiving a shielding disc having a light transmission part and the light shielding part of the different pattern for each, a light emitting unit is incident light to the plane light guide disc, the reflected light transmitted through the light transmitting portion of the light shielding disc comprising: a light receiving portion, and the optical encoder in which the light receiving portion detects the rotation angle of the light shielding disk based on the pattern of the reflected light received, the carrier sprocket tape transport that rotates in synchronization with the light-shielding disc It was.

The surface light guide disk of the present invention guides light incident from the first surface side between the first surface and the second surface and reflects it to the first surface side. The first surface and the second surface Are formed by inclined surfaces of a plurality of triangular grooves formed radially with a predetermined central angle about the central axis of the surface light guide disk, and are incident on a region partitioned by the predetermined central angle. The structure is provided with a third reflecting portion that reflects light guided between the surface and the second surface into the region, and the inner periphery within the region is suppressed while being diffused into adjacent regions. Since light is guided toward the side, light can be reflected to the first surface side with a sufficient amount of light. Therefore, the the plane light guide disc an optical encoder used can achieve high space saving and detection accuracy further, in the tape feeder using the optical encoder, the design freedom high In addition, high-precision control of the feed amount of the carrier tape 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 section with respect to one light emitting element 11a serving as a light emitting section. 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.

A planar light guide disk that can reflect light with a sufficient amount of light, an optical encoder that combines space saving and high detection accuracy, and a high degree of design freedom to control the feed amount of the carrier tape with high accuracy. to provide a tape feeder.

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 (4)

Having a first surface and a second surface facing, plane light guide for reflecting light incident from the first surface side to said first surface side and guided between the first surface and the second surface A disk,
A first reflecting part for reflecting the light incident provided annularly to one of at least near the outer periphery or inner periphery closer to the center axis of the surface light guide disc from the first surface side in the radial direction,
A second reflecting part for reflecting the light reflected plurally provided on a concentric circle around the central axis of the surface light guide disc at the first reflecting portion on the first surface side,
The first surface and the second surface are composed of inclined surfaces of a plurality of triangular grooves formed radially at a predetermined center angle centered on the central axis of the surface light guide disk, and at the predetermined center angle A surface light guide disk including a third reflecting portion that reflects light that enters a partitioned region and is guided between the first surface and the second surface into the region. 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,
The surface light guide disk according to claim 1, wherein the second reflecting portion is configured by a tapered surface formed on the second surface so as to reduce the diameter from the second surface toward the first surface. Said plane light guide disc according to claim 1 or 2,
It arranged a central axis similarly to the first surface side of the plane light guide disc, and a light shielding disc having a light transmission part and the light shielding part of the different pattern for each center angle,
A light emitting unit is incident light to the plane light guide disc,
A light receiving portion for receiving the reflected light transmitted through the light transmitting portion of the light shielding disc,
Optical encoder for detecting the rotation angle of the light shielding disk based on the pattern of the reflected light which the light receiving unit has received. Said plane light guide disc according to claim 1 or 2,
It arranged a central axis similarly to the first surface side of the plane light guide disc, and a light shielding disc having a light transmission part and the light shielding part of the different pattern for each center angle,
A light emitting unit is incident light to the plane light guide disc,
A light receiving unit for receiving the reflected light transmitted through the light transmitting portion of the light shielding disc,
And an optical encoder for detecting the rotation angle of the light shielding disk based on the pattern of the reflected light which the light receiving unit has received,
Tape feeder having a carrier sprocket tape transport that rotates in synchronization with the light shielding disk.

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