JPH01131416A - Optical encoder - Google Patents

Abstract

PURPOSE:To easily detect the origin of a pattern for detection by providing an origin detection mark which indicates the origin of a code pattern formed on an encoder plate. CONSTITUTION:The bar code pattern 22 which repeats at specific intervals is formed in the rotating direction of the encoding disk 21, its origin pattern 22o is extended toward the center to form an origin position pattern 22s, and the origin detection pattern in an arrow shape is formed corresponding to the tip part of the pattern. The pattern 22o is formed of more bits than any other pattern, a series of origin position patterns 22s are formed, and the surface including the code patterns 22 and parts between the patterns is formed as a reflecting surface. Then, the mark 23 is formed as a nonreflection surface independently of the code pattern 22 so that it is easy to see. The patterns 22o is easily confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical encoder that uses laser light to detect rotational or linear displacement.

[Summary of the invention]

The present invention irradiates a laser beam from a laser light source onto an encode plate on which a code pattern is repeated at predetermined intervals in the direction of detection movement, and supplies the irradiated light to a detection means consisting of a detector via the encode plate. An optical encoder that detects a rotational or linear displacement amount of 1 itu,
By providing a mark for detecting the origin on the encode plate, the position of the origin code pattern can be easily confirmed, and the efficiency of attachment and adjustment of the encode plate to the motor, robot arm, etc. is improved. .

[Conventional technology]

In a rotary encoder that uses a semiconductor laser to detect the amount of rotational displacement, a laser beam is irradiated onto a rotary encoder plate that has a striped detection pattern formed in the radial direction, and the reflected light is detected to detect the amount of rotational displacement. There is something to do. FIG. 11 shows an example of this rotary encoder.

In the figure, (1) is a disk constituting an encoding board. On the surface of this disk (1), striped detection patterns extending in the radial direction are formed continuously in the circumferential direction. That is, striped pit portions (2A) and mirror surface portions (2B) are alternately formed at a ratio of, for example, I:1.

Further, (4) is a semiconductor laser constituting the optical big amplifier (3), and the laser beam LB from this semiconductor laser (4) is transmitted to a grating plate (diffraction grating) (5).
) and is supplied to the collimating lens (6) to be made into parallel light beams. The laser beam LB from this collimating lens (6) is supplied to an objective lens (9) through a polarizing beam splitter (7) and a quarter-wave plate (8). Then, the laser beam LB is focused by this objective lens (9) so that it is focused on the surface of the disk (1).

In reality, since the grating plate (5) is arranged, the laser beam LB is divided into three beams, and on the surface of the disk (11), in addition to the main beam LBl, there are two sub-beams LBO2 and LB20. Beam LI3+
It is shifted back and forth to the position where + is sandwiched. Figure 12 shows this state, where the laser beams LBO2, LB
I1. The LBs 20 are lined up in a line in this order, and the line direction intersects the radial direction of the disk 11), that is, the direction of the focus portion (2^), at a required angle, as shown by the center line AA' in FIG. It is designed to correspond to

Here, the laser beam LB (LB禦* LB 02
When the +LB20) hits the bit part (2^), it spreads around and does not return to the objective lens (9), but it does not return to the mirror part (2^).
When it hits B), it is specularly reflected and most of it hits the objective lens (9)
Return to

The laser beam LH reflected by the mirror surface (2B) is 1/4
It passes through a wave plate (8) and is supplied to a polarizing beam splitter (7). The laser beam LB reflected by the polarized beam splinter (7) is focused by a condenser lens (10) and a cylindrical lens (11), and is supplied to a photodetector (12).

Therefore, when rotation is transmitted to the disk (1) from the outside, the amount of the laser beam LB reflected by the disk (1) changes. A photodetector (12) detects the changing name.
If detected, the amount of rotational displacement can be determined.

[Problem that the invention seeks to solve]

In a rotary encoder configured in this way, the detection pattern formed on the disk is submicron.
It is very difficult to identify only one specific pattern in fine patterns that are repeated at a pitch of several microns. This is the same for the pattern that indicates the zero position (origin), so if you want to get a rough idea of the zero position, an expert can detect and mark the zero position in advance, or find the zero position by observing it with a microscope. Therefore, there is a drawback that mounting and adjusting the encode disk to the motor, the arm of the robot, etc. is inefficient.

In view of this, an object of the present invention is to provide an optical encoder that has a simple configuration and can easily detect the origin of a detection pattern on an encoder plate.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an encoder plate having a code pattern that repeats at predetermined intervals in the direction of detection movement, a light source that emits a laser beam, and an encoder plate. The encoder is provided with a detection means consisting of a detector that detects the irradiated light from the light source via the encoder plate, and a mark for detecting the origin is provided on the encoder plate.

[Effect]

By providing an origin detection mark that indicates the origin of the code pattern formed on the encoder board,
When installing the encoder plate to the encoder body,
The origin detection mark allows you to easily check the origin pattern position of the code pattern and accurately align the origin.
After this alignment is performed, final fine adjustment is performed using electrical signals, thereby making it possible to more accurately align the origin.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 10.

FIGS. 1 and 2 are an overall perspective view and an enlarged plan view of a portion of an encode plate, that is, an example of an encode disk, commonly used in a rotary encoder as an optical encoder of the present invention.

In FIGS. 1 and 2, a code pattern (22) is formed on an encoding disk at a predetermined interval in the rotational direction, and this code pattern (22)
The origin pattern (22o) is extended toward the center to form an origin position pattern (22"), and an arrow-shaped origin detection mark (23) is formed corresponding to the tip of this origin position pattern (22"). is formed.

In this encode disk (21), each pattern of the code pattern (22) is
1) A plurality of pits are arranged in the radial direction with a minimum pitch, and the entire pattern is formed as a groove-like pattern of the required length, and the origin pattern (22o) is formed longer with a larger number of pits than the other patterns. The origin position pattern (2
2”) is formed in a series, and this code pattern (2”) is formed in a series.
2) The surface including the portion between the patterns is formed as a reflective surface.

The origin detection mark (23) is a code pattern (
Unlike 22), it is formed as a non-reflective surface so that it can be visually detected, and the origin pattern (22o) can be easily confirmed. Also, this mark (
By coloring 23), visual confirmation can be made even easier.

FIG. 3 is an enlarged plan view of a part of the other side of the encode disk, showing an origin detection mark (23) formed corresponding to the origin pattern (22o) of the code pattern (22) formed on the encode disk (21). ) is an origin position pattern (22o) whose − side edge is an extension of the origin pattern (22o).
22"). This origin detection mark (23) is also formed as a non-reflective surface in the same way as in the embodiment described above, and can also be displayed in color.

Next, FIG. 4 is an enlarged plan view of a portion of the encode plate used in the teno-linear encoder as the optical encoder of the present invention, in which the encode plate (31) has a code pattern (32) that repeats at predetermined intervals in the longitudinal direction. is formed, and the origin pattern (
32o) is extended toward both ends to form the origin position pattern (3
2”) is formed, and this origin position pattern (32”) is formed.
”) Corresponding to the end of the arrow-shaped origin detection mark (3
3) is formed.

Also in this encode plate (31), the origin detection mark (33) is formed as a non-reflective surface and is colored, unlike the code pattern (32) as in the embodiments shown in FIGS. 1 to 3 described above. Also, the shape of this mark (33) can be formed into a quadrilateral shape, a trapezoid shape, etc. whose minus side edge coincides with the origin position pattern (32''), similarly to the embodiment shown in FIG.

Next, the manufacturing process of the encode disk (21) on which the code pattern (22) described above is formed will be explained with reference to FIG.

First, as shown in FIG.
A glass master disk (43) is formed by uniformly applying the glass to a thickness of -

While rotating this glass master disk (43) at a constant speed by a spindle motor M as shown in FIG.
The following spot light is irradiated onto the surface of the photoresist (42) for exposure. At this time, the laser beam (44) is repeatedly turned on and off the same number of times as the number of patterns required for the encoding disk while the glass master (43) rotates once, and the irradiation position is moved in the radial direction of the glass master (43). Move at a constant speed.

After exposing the photoresist (42) in this way, a development process is performed as shown in FIG. When using a positive photoresist, the exposed areas melt and pit (4
2a) is formed. Furthermore, when a negative photoresist is used, the unexposed portions melt and the exposed portions remain, forming pits. In this way, a series of pins (42) are arranged in the radial direction of the glass master (43).
The group a) corresponds to the code pattern (22) described above. The pit row forming the origin pattern (22o) is formed longer than the pit rows of other patterns, that is, the number of focuses is increased.

Thereafter, through an electroforming process, a metal master (46) is produced as shown in the same figure. This metal master (
46) is peeled from the glass group 1 (41), and from this metal master (46), the metal mother (46) is removed as shown in Figure E.
47).

Then, a stamper (48) is produced from this metal mother (47) as shown in FIG. At this time, the metal master (46) produced in the process shown in the figure may be used as the stamper (48).

A flat glass disk (4) that will become the substrate of the encode disk (21) is attached to the stamper (48) produced in this way.
9), and a resin (50
).

That is, as shown in an enlarged view in FIG. Then, a spacer disk (52) having a predetermined thickness and a predetermined diameter, that is, equal to the thickness of the resin (50) and approximately the same diameter as the center attachment area of the encoder disk, is placed in the center of the stamper (48). ) is inserted and placed on the central shaft (51a). Then, attach the glass disk (49) to the stamper (
48), its center hole (49a) is inserted into the center shaft (51a) of the plywood (51), and the center surface is placed and abutted on the spacer disk (52), and a predetermined pressure is applied from above. By applying pressure, a gap having a predetermined thickness, that is, the thickness of the spacer disk (52), is formed between the stamper (48) and the stamper (48).

Therefore, in the gap between the glass disk (49) and the stamper (48), the resin (500
) is press-fitted and the wood JJM (50) is cured by irradiating ultraviolet rays from the glass disk (49) side.

After the resin (50) hardens, the glass disk (49) is peeled off from the stamper (48), and the pits (50a) forming the code pattern are transferred to the resin (50) on the surface of the glass disk (49). A disc is produced. Therefore, the surface of this disk, that is, the resin layer (5
0) is coated with a metal film (
(53) (hereinafter referred to as a reflective film) is formed by vapor deposition or sputtering. When forming this reflective film (53),
Masking in the shape of the origin detection mark (23) is applied to the part corresponding to the pit row forming the origin position pattern (22'') described above, and in this state, the reflective film (53) is deposited or sputtered, and then the masking is performed. By peeling off, an origin detection mark (23) is formed in a cut-out shape on the surface of the reflective film (53).

Finally, as shown in Figure I, a protective layer (54) is formed to protect the reflective film (53). This protective layer (
54) is formed so as not to cover the center surface of the glass disk (49), that is, the attachment area (49b), and is formed so that the surface of the glass disk (49) is exposed in the attachment area (49b).

An encoded disc (21) is manufactured through the above steps. The resin JiJ (50) for pit transfer is formed on the encoder disk (21) (7) glass disk (49) as a substrate. Since the process is carried out in pressure contact with the disk (52), the resin is completely prevented from entering the center mounting area, and the thickness of the resin layer (50) can be precisely controlled and formed to a predetermined thickness. In the formation of the membrane (53) and the formation of the protective layer (54), the central attachment area (49) is
By masking b), the surface of the glass disk (49) is exposed in the center attachment area (49b), making it possible to accurately and stably attach the attachment member to the encode disk (21) at its center. can.

Then, this encode disk (21) has an origin detection mark (23") corresponding to an origin position pattern (22") of a code pattern (22) formed by a row of reflective pits.
) is formed in a hollow shape, that is, as a non-reflective surface, so that it can be clearly seen from the outer surface side, and the position of the origin pattern (22o) can be easily confirmed.

Although the manufacturing process of an example of an encode disk has been described above, an encode plate that can be used in a linear encoder as shown in FIG. 4 described above can also be formed in the same manner.

In other words, in the case of this encode plate, the glass master disk is rectangular, and while moving at a constant speed in the longitudinal direction, the photoresist on the surface is irradiated with a laser beam as a spot light, and turned on and off the same number of times as the number of patterns required. After exposing the glass master by repeatedly moving the irradiation position toward the center of the glass master at a constant speed, development processing is performed to form a focus row corresponding to the code pattern. From the glass master disk thus formed, a metal master, a metal mother, and a stamper are formed in the same manner as the encoded disk described above, and pits are transferred onto the surface of a flat glass plate as a substrate using a resin layer to form a code pattern. An encode plate can be formed by forming an origin detection mark corresponding to the origin position pattern.

Above, we have described an example in which the mark for detecting the origin, which is formed corresponding to the origin position pattern of the code pattern formed on the encode disk and the encode plate, is formed as a non-reflective surface, and the manufacturing process thereof. An encode disk and an encode plate in which marks for detecting the origin are formed as a diffused reflection surface will be described with reference to FIGS. 6 to 10.

What is shown in FIG. 6 is the origin pattern (22o) of the code pattern (22) formed on the encode disk (21).
) is formed by a pit row of pits P that are the same size or slightly smaller than the pits forming the code pattern (22).
Pit p are arranged and formed so as to be continuous with the tip of the origin position pattern (22s), which is an extension of the origin pattern (22o), so as to form an arrow shape as a whole.

In this way, the detection mark (123) is formed as an uneven surface by arranging the vias, so that the entrance light is scattered and diffusely reflected, so it can be clearly distinguished from the surrounding specular reflection surface and can be seen visually. The origin pattern (
22o) can be easily confirmed visually.

Figure 7 shows the origin detection mark (123) of the code pattern (22) of the encode disk (21) formed in a quadrilateral shape (trapezoid) as a whole by the arrangement of pits p, with the - side edge located at the origin. It is formed to match the extending direction of the pattern (22s).

8 and 9 show the origin detection mark (123) of the code pattern (22) of the encode disk (21) formed as an uneven surface by the arrangement of group g. Similar to the one shown, the tip of the origin position pattern (22g) is formed in the shape of an arrow as a whole, and in FIG. The side edges are formed to match the extension direction of the origin position pattern (22s).

Even in the case where the origin detection marks (123) are formed in the arrangement of group g, the entrance light is scattered and diffusely reflected, and the origin pattern (22o) can be clearly distinguished from the surrounding specular reflection surfaces. It can be easily confirmed visually.

As described above, the bit string and group string that form the origin detection mark (123) on the encode disk (21) are formed in the same manner as the pits that form the code pattern are cut on the glass master disk in the manufacturing process of the encode disk described above. be able to.

That is, to manufacture the encoded disk, as described above, a stambar is formed from a glass master disk on which a code pattern has been cut, and the code pattern is transferred to the glass disk by the so-called 2P method, which hardens the resin using ultraviolet rays or the like. Therefore, there is no discrepancy between discs,
Accuracy can be ensured, and by forming the origin detection mark (123) by applying the code pattern cutting technique, the positional accuracy relative to the origin position pattern (22s) can be sufficiently satisfied.

Moreover, since the encode disk (21) has the origin detection mark (123) formed in the same way as the code pattern (22), the reflective film can be formed in the same manner as when the origin detection mark (123) is not formed. This can be done without using masking, improving productivity.

The above is a case where the origin detection mark is formed on an encode disk, but it can be similarly formed on an encode plate commonly used in a linear encoder.

That is, as shown in FIG.
1r6 at the end of the origin position pattern (32s) formed to extend to the origin pattern (320) of the code pattern (32) repeatedly formed at predetermined intervals in the longitudinal direction.
The origin detection mark (133) is formed in the shape of an arrow by an arrangement of pits p.

In this case, the origin detection mark (133) is also clearly distinguished from the specular reflection surface as a diffused reflection surface, and the origin pattern (32o
) can be easily confirmed visually.

Also in this encode plate (31), the origin detection mark (133) is formed into a quadrilateral shape, trapezoid shape, etc. whose negative side edge coincides with the origin position pattern (32s) in the same way as in the embodiment shown in FIG. can.

Further, this origin detection mark (133) can be formed as a diffused reflection surface by arranging groups similarly to the embodiments shown in FIGS. 8 and 9 described above.

The origin detection mark (133) formed by the bit string or group string in this way can be formed in the same way as the code pattern (32) in the manufacturing process of the encode plate (31), and the encode plate formed in this way (31) has the same effect as the encoding disk (21) shown in FIGS. 6 to 9 described above.

Although the present invention has been described in detail above, the present invention is not limited to these embodiments, and can be modified in various ways without departing from the spirit of the invention.

For example, the encode disk and encode plate use flat glass disks and flat glass plates as substrates, but resin disks and plates with good optical properties can also be used, and the origin position pattern is the same as the origin pattern of the code pattern. Although the origin position pattern is formed as an extension, the origin position pattern may be formed apart from the code pattern.

Further, the pit row forming the code pattern can be formed so that each pit overlaps, so that the entire pit is formed in a perfect groove shape.

The type of optical encoder is not limited to the reflective type as in the embodiment, but may be a transmissive type.

〔Effect of the invention〕

As described above, according to the present invention, since the origin detection mark is formed corresponding to the origin position pattern of the code pattern of the encode board, the origin position of the encode board can be seen at a glance. It improves efficiency when attached to a robot arm, and is particularly effective when used to detect displacement of a robot arm, where the drive range is limited to a required angle and there is a directionality of attachment.

Furthermore, if the origin of the encoder plate is lost for some reason during encoder adjustment, the position can be immediately found by visual inspection, and the adjustment can be carried out efficiently.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an example of an encoding disk applied to the present invention, FIG. 2 is an enlarged plan view of a portion of the encoding disk shown in FIG. 1, and FIG. 3 is an enlarged plan view of a portion of the other side of the encoding disk. , FIG. 4 is an enlarged plan view of a portion of an example of an encode plate, FIGS. 5A to 1 are explanatory views of the manufacturing process of the encode disk shown in FIG. 9 to 9 are enlarged plan views of a portion of the other side of the encode disk, FIG. 10 is an enlarged plan view of a portion of the other side of the encode plate, and FIG.
The figure is a configuration diagram of an example of an optical encoder, and Figure 12 is the first
2 is a diagram for explaining the encoder shown in FIG. 1. FIG. In the figure, (21) and (31) are an encode disk and an encode plate, (22) and (32) are code patterns, (22o) and (32o)
) is the origin pattern, (22s) and (32s) are the origin position patterns, (23) , (123) and (33)
. (133) is a mark for detecting the origin.

Claims (1)

[Scope of Claims] Consisting of an encoding plate on which a code pattern is formed that repeats at predetermined intervals in the direction of detection movement, a light source that emits laser light, and a detector that detects the irradiated light from the light source via the encoding plate. What is claimed is: 1. An optical encoder comprising: a detection means, and a mark for detecting an origin is provided on the encoder plate.