JPH1114405A - Optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absolute optical encoder which has a simple structure and is suitable for miniaturization. SOLUTION: A- and B-phase detecting pattern 11 in which many recessing and projecting sections are arranged at regular pitches and a Z-phase detecting pattern 12 composed of one or a plurality of slits are formed on the same track of a rotatably supported code disk 10 and a light emitting element 13 and a first light receiving element 14 are arranged closely to each other in a state where the elements 13 and 14 are faced oppositely to one surface of the disk 10. At the same time, a second light receiving element 15 is provided in a state where the element 15 is faced oppositely to the other surface side of the disk 10. When the disk 10 is rotated in either the normal direction or reverse direction, A- and B-phase signals having a phase difference of 90 deg. between them are outputted from the first light receiving element 14, because the light emitted from the light emitting element 13 is reflected by the A- and B-phase detecting pattern 11 and a Z-phase signal is outputted from the second light receiving element 15, because the light emitted from the light emitting element 13 is passed through the Z-phase detecting pattern 12. Therefore, the rotating direction, rotational amount, and absolute position of the disk 10 can be found based on the A-, B-, and Z-phase signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary or linear optical encoder, and more particularly to an absolute type optical encoder capable of detecting an absolute position.

[0002]

2. Description of the Related Art An absolute type optical encoder detects the rotation direction and the amount of rotation from A and B phase detection patterns provided on a code plate, and detects an absolute position from a Z phase detection pattern also provided on a code plate. Is widely used in various fields including a steering angle sensor for detecting a steering angle and a steering direction of a vehicle-mounted steering wheel.

FIGS. 4 to 6 show a conventional example of such an optical encoder. FIG. 4 is a plan view of a code plate, and FIG.
FIG. 6 is a cross-sectional view showing a detection part of A and B phases, and FIG. 6 is a cross-sectional view showing a detection part of Z phase. In these figures, reference numeral 1
The code plate indicated by is mounted on a rotating shaft or the like (not shown) and rotatably supported. On the different tracks P1 and P2 of the code plate 1, A, B phase detection patterns 2 and Z phase detection patterns 3 are provided. Each is formed. The A and B phase detection patterns 2 are composed of a large number of slits (holes) formed at equal pitches on the track P1. As shown in FIG. 5, the first light emitting element 4 and the first light emitting element 4 pass through these slits. Are arranged facing each other. The first light receiving element 5 has at least two light receiving surfaces, and outputs A and B phase signals having a phase difference of 90 degrees from each light receiving surface. In addition, the Z-phase detection pattern is one on the track P2.
Alternatively, a plurality of slits are formed, and as shown in FIG. 6, a pair of the second light emitting element 6 and the second light receiving element 7 is arranged to face each other through the slit. The second light receiving element 7 has at least one light receiving surface, and outputs a Z-phase signal from the light receiving surface.

In the optical encoder constructed as described above, when the code plate 1 rotates in either the forward or reverse direction, the light emitted from the first light emitting element 4 during the rotation is used to detect the A and B phases. The light passes through the slit of the pattern 2 and is received by the first light receiving element 5, and the first light receiving element 5 outputs an A-phase signal and a B-phase signal having a phase difference of 90 degrees. Similarly, while the code plate 1 is rotating, light emitted from the second light emitting element 6 passes through the slit of the Z-phase detection pattern 3 and is received by the second light receiving element 7. Outputs a Z-phase signal. Accordingly, the rotation direction and the rotation amount (angle) of the code plate 1 can be obtained from the A-phase signal and the B-phase signal, and the absolute position of the code plate 1 can be obtained from the Z-phase signal. The rotation information of the connected rotating body can be obtained.

The A, B phase detection pattern 2 and the Z phase detection pattern 3 are formed by a reflection part and a non-reflection part instead of the above-mentioned slit, and the light emitted from the first light emitting element 4 is A, B The first light reflected by the reflecting portion of the B-phase detection pattern 2
And the light emitted from the second light emitting element 6 is reflected by the reflecting portion of the Z-phase detection pattern 3 and received by the second light receiving element 7. Are known.

[0006]

However, in the above-described conventional optical encoder, the first light emitting / receiving elements 4, 5 and the Z phase detection pattern 3 are detected to detect the A and B phase detection patterns 2. In addition, another second light emitting / receiving element 6, 7, that is, two sets of elements 4 to 7 must be mounted at predetermined positions on the printed circuit board. There is a problem that miniaturization is hindered by space.

[0007]

According to the present invention, there is provided a light receiving element for receiving one of an A / B phase detection pattern and a Z phase detection pattern formed on a code plate and receiving a reflected light thereof. An element is detected, and the other is detected by the light emitting element and a second light receiving element that receives the transmitted light. With this configuration, since the A and B phase signals and the Z phase signal are respectively output from the first and second light receiving elements using the light emitted from the common light emitting element, the required number of elements is reduced. Not only can it be possible, but also the size of the printed circuit board on which those elements are mounted can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an optical encoder according to the present invention,
A rotatable or linearly movable code plate, A, B-phase detection patterns and Z-phase detection patterns formed on the code plate, a light-emitting element and a first light-receiving element arranged on one side of the code plate; An element and a second light receiving element disposed opposite to the other side of the code plate, and by reflecting light from the light emitting element on the code plate and receiving the light on the first light receiving element, A signal from one of the A, B, and Z phases is detected, and light from the light emitting element is transmitted through the code plate and received by the second light receiving element, whereby the A, B, and Z phases are detected. The other signal is detected.

The A and B phase detection patterns and the Z phase detection pattern may be formed on separate tracks which are close to each other. However, if these two detection patterns are formed on the same track, the diameter of the code plate becomes smaller. The size can be reduced, and the size of the device can be reduced.

[0010]

Embodiments will be described with reference to the drawings.
FIG. 1 is a plan view of a code plate provided in an optical encoder according to an embodiment, and FIG. 2 is a cross-sectional view showing a detection portion of the optical encoder. As shown in these drawings, the code plate is rotatably supported. On the same track P of the code plate 10, A,
A B-phase detection pattern 11 and a Z-phase detection pattern 12 are respectively formed. The A and B phase detection patterns 11 are composed of a number of uneven portions formed at equal pitch intervals on the track P, while the Z phase detection pattern 12 is composed of one or a plurality of slits formed on the track P. Corresponds to an arbitrary concave portion of the A and B phase detection patterns 11.

As shown in FIG. 2, a light-emitting element 13 and a first light-receiving element 14 are arranged close to one surface of the code plate 10.
Are opposed to the uneven portions of the A and B phase detection patterns 11.
The first light receiving element 14 has at least two light receiving surfaces, and outputs A and B phase signals having a phase difference of 90 degrees from each light receiving surface. Further, a second light receiving element 15 is arranged on the other surface side of the code plate 10, and the second light receiving element 15 and the light emitting element 13 face each other on the same line via the code plate 10. The second light receiving element 15 has at least one light receiving surface, and outputs a Z-phase signal from the light receiving surface. Note that an LED is used as the light emitting element 13,
As the first and second light receiving elements 14 and 15, photo transistors or photo ICs are used.

In the optical encoder thus configured, when the code plate 10 rotates in either the forward or reverse direction, the light emitted from the light emitting element 13 and reflected by the convex portions of the A and B phase detection patterns 11 Only the light received by the first light receiving element 14 and the light emitted from the light emitting element 13 and applied to the recesses of the A and B phase detection patterns 11 and the slits of the Z phase detection pattern do not return to the first light receiving element 14. Therefore, A having a phase difference of 90 degrees from each light receiving surface of the first light receiving element 14
A phase signal and a B-phase signal are output. Similarly, the code plate 10
The light emitted from the light emitting element 13 passes through the slit of the Z-phase detection pattern 12 during rotation of the second light receiving element 15.
, The second light receiving element 15 outputs a Z-phase signal. Therefore, the rotation direction and the rotation amount (angle) of the code plate 10 can be obtained from the A-phase signal and the B-phase signal, and the absolute position of the code plate 10 can be obtained from the Z-phase signal. The rotation information of the connected rotating body can be obtained.

In the embodiment shown in FIG. 3, the A and B phase detection patterns 11 are composed of a large number of slits formed at equal pitch intervals on tracks P of the code plate 10, and the light emitting element 13 and the second One light receiving element 14 is disposed to be substantially co-linear and opposed. On the other hand, the Z-phase detection pattern 12
Is composed of a reflecting surface formed at an arbitrary portion between the slits, and the light emitting element 13 and the second light receiving element 15 are arranged in close proximity to the reflecting surface.

In the optical encoder configured as described above, when the code plate 10 rotates in either the forward or reverse direction, the light emitted from the light emitting element 13 passes through the slits of the A and B phase detection patterns 11. The first light receiving element 14 receives light, and an A phase signal and a B phase signal having a phase difference of 90 degrees are output from each light receiving surface of the first light receiving element 14. Also,
Only the light emitted from the light emitting element 13 and reflected on the reflecting surface of the code plate 10 is received by the second light receiving element 15, and the light emitted from the light emitting element 13 and applied to the non-reflecting surface and the slit is the second light receiving element. Does not return, the second light receiving element 15 outputs a Z-phase signal.

In each of the above embodiments, the case where the A / B phase detection pattern 11 and the Z phase detection pattern 12 are formed on the same track P of the code plate 10 has been described. And Z-phase detection pattern 12
Can be formed on separate tracks close to each other.

The combination of the A / B phase detection pattern 11 and the Z phase detection pattern 12 is not limited to the above embodiment. For example, the A / B phase detection pattern 11 may be replaced with the uneven portion shown in FIG. It is also possible to output an A-phase signal and a B-phase signal by using a reflecting portion and a non-reflecting portion and receiving the light reflected by these reflecting portions by the first light receiving element 14.

[0017]

The present invention is embodied in the form described above and has the following effects.

A code plate that can be rotated or moved linearly, an A-phase detection pattern and a Z-phase detection pattern formed on the code plate, a light-emitting element and a light-emitting element that are arranged opposite to one surface of the code plate. 1 light receiving element, and a second light receiving element disposed opposite to the other surface of the code plate, wherein light from the light emitting element is reflected by the code plate and received by the first light receiving element. By detecting any one of the signals of the A, B and Z phases and transmitting the light from the light emitting element through the code plate and receiving the light by the second light receiving element, the A and B phases are detected. And the Z-phase signal are detected, the A and B-phase signals and the Z-phase signal are output from the first and second light-receiving elements using light emitted from the common light-emitting element. Reduces the number of required elements Kill well, the printed circuit board to which they element is mounted can be miniaturized.

Further, when the A, B phase detection pattern and the Z phase detection pattern are formed on the same track of the code plate,
The diameter of the code plate can be reduced, and the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a code plate provided in an optical encoder according to an embodiment.

FIG. 2 is a sectional view showing a detection portion of the optical encoder.

FIG. 3 is a cross-sectional view illustrating a detection portion of an optical encoder according to another embodiment.

FIG. 4 is a plan view of a code plate provided in a conventional optical encoder.

FIG. 5 is a cross-sectional view showing a detection portion for A and B phases of the optical encoder.

FIG. 6 is a sectional view showing a Z-phase detection portion of the optical encoder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Code board 11 A and B phase detection pattern 12 Z phase detection pattern 13 Light emitting element 14 1st light receiving element 15 2nd light receiving element

Claims (2)

[Claims] 1. A code plate that can be rotated or moved linearly, an A-phase detection pattern and a Z-phase detection pattern formed on the code plate, and a light-emitting element disposed to face one surface of the code plate. And a first light receiving element, and a second light receiving element disposed opposite to the other surface of the code plate, wherein light from the light emitting element is reflected by the code plate so that the first light receiving element By receiving the light, one of the signals of the A, B, and Z phases is detected, and the light from the light emitting element is transmitted through the code plate and received by the second light receiving element, whereby A, An optical encoder for detecting either one of the B phase and the Z phase. 2. The optical encoder according to claim 1, wherein the A and B phase detection patterns and the Z phase detection pattern are formed on the same track.