TW202001194A - Optical potary encoder - Google Patents

Abstract

This invention provides an optical rotary encoder having improved resistance against contamination. The solution of the present invention is an encoder (10) that is an optical rotary encoder provided with a disc body (30). The disk body (30) includes an M code area (31) for generating an M code signal; a Gray code area (32) for generating a Gray code signal; and an incremental area (33) for generating an incremental signal. The encoder (10) can also be an absolute encoder.

Description

Optical rotary encoder

This invention relates to an optical rotary encoder.

The optical rotary encoder is used to detect the rotational position of the rotating body. An example of the structure of a conventional optical rotary encoder is described in Patent Documents 1 to 3. As a detection method of the rotational position, a method using a Gray code, a method using an M code, a method using an incremental signal, etc. may be mentioned.

In particular, Patent Document 1 describes an example of an encoder with redundancy in a detection mechanism, and Patent Document 2 describes an example of an encoder with an error correction and detection function. An example of an encoder with anomaly detection function is described. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-53570 [Patent Document 2] Japanese Patent Laid-Open No. 5-252037 [Patent Document 3] Japanese Patent Laid-Open No. 9-105646

[Problems to be solved by the present invention]

However, the conventional optical rotary encoder has a problem that it is easily affected by contamination.

For example, when impurities or dirt are attached to a part of the code card (slots, disks, tracks, etc.), signal abnormalities may occur and normal position detection may not be performed or accuracy may deteriorate.

In addition, although it is also known to use a redundant configuration of two signals, when one of the signals is abnormal, it may not be possible to determine which signal is correct.

This invention is for researchers to solve such problems, and aims to provide an optical rotary encoder having higher tolerance to contamination. [Means to solve the problem]

The optical rotary encoder of the invention is provided with a disc body. The characteristic of the optical rotary encoder is: The aforementioned plate body is provided with: M code area, used to generate M code signal; Gray code area, used to generate Gray code signals; and The increasing area is used to generate an increasing signal. According to a specific aspect, the aforementioned encoder is an absolute encoder. According to a specific aspect, the M code region, the Gray code region, and the increasing region are respectively arranged in different radial directions. According to a specific aspect, the aforementioned encoder is equipped with a control device, The aforementioned control device is configured as follows: Based on the aforementioned M code signal, determine the M code position, Based on the aforementioned Gray code signal, the position of the Gray code is determined, Based on the aforementioned increment signal, determine the increment position, When at least two of the M code position, the Gray code position, and the incremental position match, a signal indicating the coincident position is output. According to a specific aspect, the aforementioned control device is configured as follows: When the M code position is consistent with the Gray code position and the increment position is different, the error information of the increment position is output, When the aforementioned Gray code position is consistent with the incremental position and the M code position is different, the error information of the M code position is output, When the increment position is consistent with the M code position and the Gray code position is different, the error information of the Gray code position is output. [Effect of invention]

Since the optical rotary encoder of this invention uses three types of signals to detect the rotational position at the same time, even if any one type cannot be used due to contamination, it can be based on the remaining two types of signals. Detect the correct rotation position and improve the tolerance to fouling.

Hereinafter, an embodiment of the invention will be described based on the attached drawings. Embodiment 1. FIG. 1 shows an example of the configuration of the encoder 10 according to Embodiment 1 of the present invention. The encoder 10 is an optical rotary encoder. In addition, the encoder 10 functions as an absolute encoder.

The encoder 10 includes a light emitting unit 20, a disc body 30, a reading window 40, and a light receiving unit 50. The light output from the light emitting unit 20 is indicated by an arrow L. The disc body 30 is provided with a light-shielding portion and a light-transmitting portion (slit, etc.), and the light output from the light-emitting portion 20 is blocked by the light-shielding portion or passes through the light-transmitting portion in accordance with the position of light emission and the rotational position of the disc body 30. A part of the light passing through the light-transmitting portion reaches the light-receiving portion 50 through the reading window 40, and is converted into a signal such as an electrical signal at the light-receiving portion 50.

The disc body 30 is provided with: an M code area 31 for generating an M code signal; a Gray code area 32 for generating a Gray code signal; and an increasing area 33 for generating an increasing signal. The M code area 31, the Gray code area 32, and the increment area 33 may each be composed of one or more tracks.

In the M-code area 31, the light-shielding portion and the light-transmitting portion are arranged in the circumferential direction according to a specific pattern representing the M code, and the rotation position of the disc body 30 can be uniquely specified in accordance with the pattern in the predetermined circumferential direction range. As a specific pattern, a conventional optical rotary encoder using M codes can be used. For example, the pattern described in Patent Document 2 may be used.

In the Gray code area 32, the light-shielding portion and the light-transmitting portion are arranged in the circumferential direction and the radial direction according to a specific pattern representing the Gray code, and the rotation position of the disc body 30 can be uniquely specified in accordance with the pattern of the predetermined circumferential position. The specific pattern is a pattern using a conventional optical rotary encoder using Gray code.

In the increasing area 33, the repeated patterns of the light shielding portion and the light transmitting portion are arranged in the circumferential direction along a certain period, and the rotation amount (rotation angle) of the disc body 30 can be specified in accordance with the change in the pattern of the predetermined position in the circumferential direction. Although not specifically shown, the incremental region 33 may be a combination of two repeating patterns of the same shape that differ in phase by only 1/4 cycle.

Corresponding to the M code area 31, the Gray code area 32, and the increment area 33, the reading window 40 is provided with an M code window 41, a Gray code window 42, and an increment window 43. In addition, corresponding to the M code region 31, the Gray code region 32, and the incremental region 33, the light receiving unit 50 includes an M code light receiving unit 51, a Gray code light receiving unit 52, and an incremental light receiving unit 53.

In FIG. 2, an example of the positional relationship between the disc body 30 and the reading window 40 is shown. FIG. 2 is a view from the axial direction of the disc body 30. For example, the light-emitting portion 20 is arranged in the inner direction of the paper surface in FIG. 2, and the light-receiving portion 50 is arranged in the front direction of the paper surface.

As shown in FIG. 2, the M-code window 41, the Gray code window 42, and the increment window 43 of the reading window 40 are arranged in different radial ranges, respectively. Corresponding to this, the M code area window 31, the Gray code area 32, and the increasing area 33 of the disc body 30 are also arranged in different radial directions, respectively.

As shown in FIG. 2, each area may be distributed in a plurality of radial ranges. In the example of FIG. 2, a total of eight gray code windows 42 are formed covering two radial ranges, whereby a maximum of 8-bit gray codes can be read.

In addition, although the details of the structure of the M code window 41 and the incremental window 43 are not particularly shown, these specific structures can use conventional optical rotary encoders using M codes and incremental signals, respectively. The composition of the reading window.

As shown in FIG. 1, the light passing through the M code region 31 passes through the M code window 41 and reaches the M code light receiving unit 51. The light passing through the Gray code region 32 passes through the Gray code window 42 and reaches the Gray code light receiving unit 52. Then, the light passing through the increasing area 33 passes through the increasing window 43 and reaches the increasing light receiving portion 53.

In this way, the light receiving unit 50 detects the pattern of light corresponding to each area, generates and outputs electrical signals indicating these.

As a structure for processing each signal, the encoder 10 is provided with a counter 60 and a control device 70. In addition, the encoder 10 includes a signal line connected to the light receiving unit 50, the counter 60, and the control device 70.

As the output signal line of the light receiving section 50, there are provided: an M code signal line 81 for outputting an M code signal; a Gray code signal line 82 for outputting a Gray code signal; and an incremental signal line 83 for outputting an incremental signal.

The incremental signal line 83 is connected to the input of the counter 60. The counter 60 is based on an incremental signal, for example, a count signal indicating the rotation amount (rotation angle) of the disc body 30 is generated by accumulating the number of pulse waves. The output of the counter 60 is connected with a count signal line 84, and the count signal is output to the count signal line 84.

The M code signal line 81, the Gray code signal line 82 and the count signal line 84 are connected to the input of the control device 70, and the control device 70 can receive the M code signal, the Gray code signal and the count signal.

The control device 70 determines the rotation position of the disc body 30 based on the input signals. That is, the first position (M code position) is determined based on the M code signal, the second position (Gray code position) is determined based on the Gray code signal, and the third position (incremental position) is determined based on the incremental signal.

Here, generally, the M code position, the Gray code position, and the increment position all coincide with each other. In addition, in this specification, "coincidence" refers not only to the case of strict coincidence, but also includes the case of matching within a predetermined allowable error range even when the resolution of each signal is different.

Here, when determining which absolute reference is required for the incremental position (for example, when information indicating the initial position of the disc body 30 is required, etc.), the method of assigning the absolute reference may be appropriate by those with ordinary knowledge in the field Decide. For example, the control device 70 may also perform an initialization process when power is supplied to the encoder 10, and may also obtain the initial position of the disk body 30 based on the M code signal or the Gray code signal in the initialization process (or The disk body 30 is rotated to a predetermined initial position), and the incremental position is calculated based on the amount of change from the initial position.

The control device 70 compares the determined positions and selects the correct position based on the principle of majority decision. The output of the control device 70 is connected to the rotation position signal line 85 and the error signal line 86, and the selection result is output through these signal lines.

When the M code position, the Gray code position, and the increment position all match, the control device 70 determines that the matched position is the correct position, and outputs a position signal indicating the correct position to the rotation position signal line 85. In this case, the control device 70 does not output an error signal to the error signal line 86.

When two of the M code position, the Gray code position, and the incremental position match and the remaining one is different, the control device 70 determines that the coincident position is the correct position and sends a position signal indicating the correct position Output to the rotation position signal line 85. In this case, the control device 70 outputs an error signal to the error signal line 86.

In summary, the control device 70 can output a signal indicating the matched position to the rotation position signal line 85 when two of the M code position, the Gray code position, and the increment position match.

The error signal output to the error signal line 86 may be a signal indicating only whether there is an error, and may also be a signal containing information of a specific inconsistent signal. Specifically, it is as follows. When the M code position is consistent with the Gray code position and the aforementioned increment position is different, the control device 70 outputs the error information of the increment position. When the position of the Gray code coincides with the incremental position and the position of the M code is different, the control device 70 outputs the error information of the position of the M code. When the increment position is consistent with the M code position and the Gray code position is different, the control device 70 outputs the error information of the Gray code position.

As described above, since the encoder 10 of the first embodiment uses three types of signals to detect the rotation position at the same time, even if any one type cannot be used due to contamination, it can be based on the remaining 2 Kinds of signals to detect the correct rotation position and improve the tolerance to fouling.

In addition, since it is possible to determine which of the three types of signals is abnormal and output, maintenance work becomes easier.

In the first embodiment described above, the following modifications can be applied. The arrangement of the patterns of the light-shielding portion and the light-transmitting portion in the disc body 30 can be arbitrarily deformed. Correspondingly, the pattern of the reading window 40 can also be deformed. For example, the number of Gray code windows 42 may be changed according to the number of bits of the Gray code required. In addition, when it is not necessary to detect the rotation direction, the number of the M code window 41, the Gray code window 42 and the increment window 43 may be reduced.

10‧‧‧Encoder (optical rotary encoder) 30‧‧‧Disc 31‧‧‧ M code area 32‧‧‧ Gray code area 33‧‧‧ Increasing area 70‧‧‧Control device

[Fig. 1] A diagram showing an example of the configuration of an optical rotary encoder according to Embodiment 1 of the present invention. [Fig. 2] A diagram showing the structure of the reading window of the optical rotary encoder of Fig. 1.

10‧‧‧Encoder

20‧‧‧Lighting Department

30‧‧‧Disc

31‧‧‧ M code area

32‧‧‧ Gray code area

33‧‧‧ Increasing area

40‧‧‧Reading window

41‧‧‧M code window

42‧‧‧Gray code window

43‧‧‧ incremental window

50‧‧‧Receiving Department

51‧‧‧M code light receiving department

52‧‧‧ Gray code light receiving department

53‧‧‧ Increasing light receiving department

60‧‧‧Counter

70‧‧‧Control device

81‧‧‧M code signal line

82‧‧‧Gray code signal line

83‧‧‧Incremental signal line

84‧‧‧Counter signal line

85‧‧‧rotation position signal line

86‧‧‧Error signal line

Claims (5)

An optical rotary encoder is provided with a disc body. The characteristics of the optical rotary encoder are: The aforementioned plate body is provided with: M code area, used to generate M code signal; Gray code area, used to generate Gray code signals; and The increasing area is used to generate an increasing signal. For example, the encoder of the first patent application scope, where, The aforementioned encoder is an absolute encoder. For example, the encoder of item 1 or 2 of the patent scope, in which The M code area, the Gray code area, and the increasing area are respectively arranged in different radial ranges. For example, the encoder of any one of items 1 to 3 of the patent application scope, in which The aforementioned encoder is equipped with a control device, The aforementioned control device is configured as follows: Based on the aforementioned M code signal, determine the M code position, Based on the aforementioned Gray code signal, the position of the Gray code is determined, Based on the aforementioned increment signal, determine the increment position, When at least two of the M code position, the Gray code position, and the incremental position match, a signal indicating the coincident position is output. For example, the encoder of item 4 of the patent application scope, in which The aforementioned control device is configured as follows: When the M code position is consistent with the Gray code position and the increment position is different, the error information of the increment position is output, When the aforementioned Gray code position is consistent with the incremental position and the M code position is different, the error information of the M code position is output, When the increment position is consistent with the M code position and the Gray code position is different, the error information of the Gray code position is output.

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