JPS63201521A - Optical disk for optical encoder - Google Patents

Abstract

PURPOSE:To eliminate the need for a tracking mechanism for a light emitting and receiving element by providing plural groups of pits which are formed at intervals in the circumferential direction of an optical disk radially at intervals, and projecting laser light and detecting its reflected light. CONSTITUTION:Plural pits P1 are provided at specific intervals in a track T1 in the circumferential direction of an optical disk 3 which is fitted to a rotary body and rotates together with the rotary body. The length of each pit P1 is theta1' in terms of a center angle and the intervals are theta2 in terms of the center angle. Tracks T2-Tm inside the track T1 are provided with pits P2-Pm at the same center angle theta1 and theta2 with the pit P1 and at specific radial intervals. The pits P1-Pm are formed radially at intervals d2, so even if the spot 12 of the laser light shifts radially, at least one of the pits P1-Pm can be detected as long as the spot 12 is in an area 6. Consequently, the tracking servomechanism is not necessary.

Description

TECHNICAL FIELD The present invention relates to an optical disc for an optical encoder, which can be implemented for detecting angular displacements of objects.

BACKGROUND ART A configuration in which an optical disk is attached to an object whose angular displacement position is to be detected and pits formed in the tracks of this optical disk are detected is, for example, 'vf Masaaki GO-3301.
2.

Problems to be Solved by the Invention In such prior art, in order to accurately detect pits, a tracking servo device that controls the position of a laser beam in the width direction of the track is essential. Such a tracking servo mechanism has a complicated configuration and is not preferred from the viewpoint of maintenance.

The configuration of the present invention provides an optical disc for an optical encoder that can accurately detect pits on the optical disc with a simple configuration without requiring a complicated configuration such as a tracking servo mechanism. That's true.

Means for Solving the Problems The present invention forms a plurality of pit groups spaced apart in the circumferential direction, and each pit group is formed by forming a plurality of pits aligned and spaced apart in the radial direction. This is an optical disk for an optical encoder characterized by having F.

According to the present invention, a plurality of pit groups are formed at intervals in the circumferential direction, and therefore, the pits included in these pit groups are detected to detect the angular displacement position and angular displacement direction of the optical disc. can do.

A plurality of bits constituting each bit group are formed in alignment at intervals in the radial direction. Therefore, even if the detection means that irradiates the bit with laser light and receives the reflected light is shifted in the radial direction, the circumferential position and angular displacement direction of the optical disc can be reliably detected. Therefore, the tracking servo mechanism described in connection with the prior art is not required, and the configuration becomes simple.

Example FIG. 1 is a sectional view of one embodiment of the present invention.

An optical disk 3 is fixed to an output shaft 2 of a motor 1 that drives the working end of an industrial robot Y. The surface of this optical disc 3 is detected by the detection means 4.

FIG. 2 is a plan view of a portion of the optical disc 3. FIG.

The axis of the optical disc 3 is indicated by reference numeral 5, and this axis R5 coincides with the axis of the output shaft 2.

In the area 6 having ll@Wl along the radial direction of the disk 3, there are plural tracks T1 to T1 centered on the sleeve #i5.
Tm is formed, and these tracks T1 to T- are concentric virtual circles centered on the pongee 85, and are mutually shifted in the radial direction. A plurality of bits P1 to Pm are formed on the tracks T1 to T111 at equal intervals in the circumferential direction. M area 6
Bit P1~ for each track T1~T- formed in
Let P+o be referred to as a total of m bit groups. Over a radius llA3.9 forming an angle θ1, bit P1
~P The spear extends in the circumferential direction. The width W1 of the area 6 where no bits P1 to Pω are formed between the radius @8 forming the angle θ2 and another radius line 10 is, for example, 0.71.
m16, and the radius of the disk 3 is, for example, 5 cm. The angle θ1 may be equal to the angle θ2. The optical disc 3 has a base made of polycarbonate and an aluminum layer formed on its surface. Bits P1 to P+n are formed on the aluminum layer, and a transparent protective film is provided on the aluminum layer. It is formed.

tR3 Figure 1 is an enlarged plan view of Pi, P2, etc. , P on one track, e.g. Tl)
The interval between bits P1 and P2 is 2 μm, which is the length of each bit P1 in the circumferential direction! 2 is, for example, a 2μ mark, and the radial width d1 of these bits P1 is 0.5μω.
It is. The distance d2 between the radially adjacent pins Pl and P2 is, for example, 1 μm. The diameter d3 of the spot 12 formed when the surface of the optical disk 3 is irradiated with a laser beam, which will be described later, is, for example, 1.4 to 2 μm. Bits P2 to Pi of remaining tracks T2 to T+-
+Momar: , similarly configured. Laser light spot 1
The diameter d3 of 2 is selected to a value that allows detection of at least one of the bits P1 to Pm adjacent in the radial direction of the disk 3. These bits Pi and P2 are detected.

Referring again to FIG. 1, the laser light from the semiconductor laser light source 13 is irradiated onto the optical disc 3 from the semi-transparent reflecting mirror 14 via the lens 15 to form a spot 12. As shown in FIG. The reflected laser beam from the optical disk 3 passes through the lens 15, the reflecting mirror 14, and the lens 16, and is received by the light receiving element 17.18. The light-receiving elements 17 and 18 detect pins P1 to PIfl at positions shifted in the circumferential direction of the optical disc 3.
When the optical disk 3 rotates, a phase difference is generated in the outputs from the light receiving elements 17 and 18. The output from the light receiving elements 17 and 18 is sent to the amplifier circuit 19.
．． 20 and the angular displacement direction r++ separate circuit 21
given to. The angular displacement direction determination circuit 21 includes the light receiving element 1
7. The direction of angular displacement of the optical disc 3 is determined in accordance with the phase difference of the output of 18. When the angular displacement direction determination circuit 21 detects that the optical disc 3 is angularly displaced in one direction,
The output of the light-receiving element 17 is given to the output counter 23 via the line 22, and the counter 23 is caused to count up. When the disk 3 is angularly displaced in the opposite direction, the output of the light receiving element 17 is derived from the line 24, thereby causing the counter 23 to count down. The count value of the counter 23 corresponds to the angular displacement position of the optical disc 3.

A plurality of bits P1 of the optical disc 3 are formed as described above on the track T1 to form one bit group, and similarly, a plurality of bits P2 to PI11 are formed along each track T2 to Twa, respectively. A pit group is formed for each track T2 to Tm. The pits PI to P+o of these pit groups are formed in alignment over an angle θ1 with an interval d2 in the radial direction. Therefore, even if the spot 12 of the laser beam shifts in the radial direction, as long as the spot 12 is within the area 6,
At least one of 1 to P- can be detected. Therefore, the present invention does not require the so-called F racking servo mechanism described in connection with the above-mentioned prior art for displacing the position of the laser beam spot 12 of the detection means 4 in the radial direction of the disk 3. This simplifies the process.

Figure ff14 is a sectional view of another embodiment of the present invention.

Corresponding parts of the embodiments described above are provided with the same reference numerals. The optical disc 26 used here is shown in FIG. In the flf area 6, bits P1 to P- are formed in ranks T1 to T (as in the previous embodiment). In this embodiment, furthermore, tracks S1-Sn are formed in another so-called index area 27 at positions shifted in the radial direction of area 6, and each of these tracks 81-Sn has bits Q1-Q1. It is formed.

Bits Q1-Q1 are bits P1-Pu in area 6
is within the range of the circumferential angle θ1. Bits Q1~Qn
are formed in a smaller number than the bits P1 to P1 at intervals in the circumferential direction, and these bits Ql to Qn are arranged at equal intervals in the radial direction.

The laser light from the semiconductor laser light source 13 is semi-transparently reflected.
ft28h-ra reflection tn29, translucent 11J] anti-JIHI
t31 and lens 32, the reflected light from am region 27 that is irradiated onto region 27 in the same manner as spot 12 described above is reflected by lens 32, semi-transparent reflecting mirror 31, and lens X'33.
The light is then received by the light receiving elements 34 and 35. Light receiving element 34
．． 35 receives reflected light at different positions in the circumferential direction of the optical disc 26, and their outputs have a phase difference.

The outputs of the light receiving elements 34 and 35 are provided to an angular displacement direction determining circuit 38 via amplifier circuits 36 and 37. The up-down counter 39 counts the output of the light-receiving element 34 in the same manner as the 7-up down counter 23 described above, and can thereby determine the angular displacement position of the optical disc 26. Note that the semiconductor laser light source 13, the light receiving elements 34 and 35,
The angular displacement direction tq separate circuit 38 and the counter 39 may be operated by being constantly powered by a battery, so that even if a power outage occurs in the remaining components, the stored contents of the counter 39 are retained. Ru.

When the power is turned on, such as after returning from a stop, the motor 1 slightly angularly displaces the optical disk 26 to move the light receiving element 34.
35 detects bits Q1 to Qn in area 27 for the first time, initialization circuit 41 calculates the angular displacement position of optical disc 26 based on the output of counter 39 and sets it in counter 23. Optical disc 2 after that
The angular displacement position of No. 6 can be detected with high accuracy by counting by the counter 23 by detecting bits P1 to PIIl. The count value of the counter 39 is a relatively small value, and therefore it is possible to reduce the power consumption by the battery 40, and thus it is possible to constantly detect the absolute position of the optical disc 26.

In the embodiments shown in FIGS. 4 and tIS5, in the IJt area 27, the pit groups Ql to Qn for each track 81 to Su are arranged at intervals in the radial direction. As long as the laser beam from the lens 32 is within the area 27, the angular displacement position of the disk 26 in the circumferential direction can be detected even if the laser beam deviates in the radial direction. No servo mechanism required.

Pit P1~P Tsuru, Q1~Q n is disk 3.26
Manufacturing can be easily carried out by engraving bits using a laser beam or the like while solidly rolling the material, resulting in excellent productivity. If, in order to avoid the need for a tracking servo mechanism, the bits should be placed in the radial direction of the disk 3.26.
It is also conceivable to form a large shape (for example, Japanese Patent Application Laid-Open No. 1983-
1.60716), but in order to form such a bit, it is necessary to individually form the bits so that they extend in the radial direction using a laser beam or the like while the rotation of the optical disk 3.26 is stopped. Productivity is extremely poor.

The embodiments described above solve this problem.

In Example 1 of FIGS. 4 and 5, the lens 15,
The focus servo mechanism 42 that drives the focus servo mechanism 32 can be the same.

Effects As described above, according to the present invention, a plurality of bit groups are formed at intervals in the circumferential direction, and each pit group has a plurality of bits arranged in a row at intervals in the radial direction. Therefore, in order to detect those bits, it is not necessary to use a tracking servo mechanism located in the United States, so the configuration is simple and inexpensive! ): allows the angular displacement position and angular displacement direction to be separated by trJ.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. m2 is a plan view of a part of the optical disc 3 shown in FIG. 1, and FIG.
4 is a sectional view of another embodiment of the present invention, and FIG. 15 is a plan view of a part of the optical disc 26 of the embodiment shown in FIG. 1. 2... Output shaft, 3, 26... Optical disk, 4...
Detection means, 6, 27... Area, 13... Semiconductor laser light source, 17.18, 34.35... Light receiving element, 21
．． 38... Angular displacement direction discrimination circuit, 23.39... Up-grain counter, 40... Battery, 41...
Initialization circuit, T1-Tm, S1-8n-) rack,
P 1- P +n, Q'1~Q ++... Bit agent Patent attorney Shikyo Keibu Figure 2 Figure 3

Claims (1)

[Claims] An optical disk for an optical encoder, characterized in that a plurality of pit groups are formed at intervals in the circumferential direction, and each pit group has a plurality of pits arranged in a row at intervals in the radial direction. .