Encoder

Abstract

Provided is an encoder which can suppress a degradation of detection accuracy. This encoder comprises: a moving plate; a light irradiation unit which irradiates a code pattern with light; and a light reception unit. The code pattern is configured from a light guide unit, and a non-light guide unit. An arrangement of the code pattern is obtained by inserting an error correction code for correcting an error into a position information data stream for which a position can be specified. The light reception unit comprises a position detection light reception element which reads the position arrangement of the code pattern, and a position correction light reception element which outputs information for correcting the error.

Description

[Technical Field]

[0001] The present disclosure relates to an encoder, and more particularly to an encoder for detecting the rotational position of a rotating body or the movement position of a linearly moving body. [Background technology]

[0002] Conventionally, encoders that detect the rotation of a rotating shaft of a motor have been known. For example, Patent Document 1 discloses an encoder that has a pattern along a measurement direction, a light source that emits light onto the pattern, and a plurality of light-receiving elements that are arranged along the measurement direction and configured to receive the light that is emitted from the light source and transmitted through or reflected by the pattern. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-118486 Summary of the Invention

[0004] However, in the encoder described in Patent Document 1, if dust or the like adheres to the pattern, the dust or the like makes it difficult for the light from the light source to transmit or reflect, which can result in false detection. In this case, the encoder cannot recognize the false detection, resulting in a problem of reduced detection accuracy.

[0005] Furthermore, even if the encoder recognizes that an erroneous detection has occurred, it is difficult to correct the error, and the rotational position cannot be detected.

[0006] The present disclosure has been made to solve such problems, and aims to provide an encoder that can detect and correct error locations even when a false detection occurs.

[0007] The encoder according to the present disclosure comprises a moving plate, a light emitting unit, and a light receiving unit. The moving plate comprises a code pattern. The code pattern is composed of light guiding units and non-light guiding units. The code pattern is arranged by inserting an error correction code for correcting errors into a position information data string that can identify a position. The light emitting unit irradiates light onto the code pattern. The light receiving unit comprises a position detection light receiving element and a position correction light receiving element. The position detection light receiving element reads the position arrangement of the code pattern. The position correction light receiving element outputs information for correcting the error.

[0008] According to the encoder of the present disclosure, position detection errors caused by foreign matter can be recognized and corrected, and a decrease in detection accuracy can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of an optical encoder according to first to fifth embodiments of the present disclosure. [Figure 2] FIG. 1 is a diagram illustrating a configuration of a main part of an optical encoder according to a first embodiment. [Figure 3] FIG. 4 is a flowchart illustrating a process of determining and correcting an error location in a signal in the optical encoder according to the first embodiment. [Figure 4] FIG. 1 is a diagram illustrating the operating principle of the optical encoder according to the first embodiment. [Figure 5A] 10A and 10B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the first embodiment. [Figure 5B] 10A and 10B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the first embodiment. [Figure 6A] FIG. 2 is a diagram illustrating an error correction method for an optical encoder according to the first embodiment. [Figure 6B] FIG. 2 is a diagram illustrating an error correction method for an optical encoder according to the first embodiment. [Figure 7]FIG. 10 is a diagram illustrating the operating principle of the optical encoder according to the second embodiment. [Figure 8A] 10A and 10B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the second embodiment. [Figure 8B] 10A and 10B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the second embodiment. [Figure 9] 10A and 10B are diagrams illustrating the effect of detecting an error portion when different types of foreign matter cover two consecutive portions of a code pattern in the optical encoder according to the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating the operating principle of the optical encoder according to the third embodiment. [Figure 11A] FIG. 11 is a diagram showing the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the third embodiment. [Figure 11B] FIG. 11 is a diagram showing the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the third embodiment. [Figure 12] FIG. 10 is a diagram illustrating the operating principle of the optical encoder according to the fourth embodiment. [Figure 13A] 13A and 13B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the fourth embodiment. [Figure 13B] 13A and 13B are diagrams illustrating the effect of detecting an error portion when a foreign object covers one portion of a code pattern in the optical encoder according to the fourth embodiment. [Figure 14A] FIG. 13 is a schematic diagram illustrating an example of an optical encoder according to a sixth embodiment. [Figure 14B] FIG. 13 is a perspective view of a moving body of an optical encoder according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0011] Furthermore, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0012] FIG. 1 is a schematic diagram illustrating the configuration of optical encoders 100, 200, 300, and 400 according to first to fifth embodiments of the present disclosure. Each of the optical encoders 100, 200, 300, and 400 includes a rotating plate 1, a light emitting unit 3, a light receiving unit 4, a determination unit 8, and a correction unit 9. The rotating plate 1 has, for example, a disk shape. The rotating plate 1 is attached so that the rotation axis SH of a rotating body 21, such as a motor, and the central axis of the rotating plate 1 are coaxial with each other and so that the main surface of the rotating plate 1 is perpendicular to the rotation axis SH. The code pattern 2 is provided on the main surface of the rotating plate 1, facing away from the rotating body 21 when viewed from the rotating plate 1. The code pattern 2 has a circumferential shape centered on the rotation axis SH. The light emitting unit 3 and the light receiving unit 4 are provided on the main surface of a fixed portion 22, which is a substrate, facing the code pattern 2. The determination unit 8 and the correction unit 9 are provided on the surface of the fixed unit 22 opposite to the main surface on which the light irradiation unit 3 and the light receiving unit 4 are provided. The light irradiation unit 3 has, for example, an LED (Light Emitting Diode). The light receiving unit 4 has, for example, a light receiving element. Light α emitted from the LED of the light irradiation unit 3 irradiates the code pattern 2, and the light α reflected by the code pattern 2 and returned is received by the light receiving element of the light receiving unit 4. The light receiving unit 4, the determination unit 8, and the correction unit 9 are electrically connected. The determination unit 8 has, for example, an electronic circuit. The determination unit 8 processes the signal of the light α received by the light receiving element of the light receiving unit 4. Furthermore, the correction unit 9 has, for example, an electronic circuit. The correction unit 9 processes the signal from the determination unit 8.

[0013] (Embodiment 1) Fig. 2 is a diagram showing the configuration of a main part of the optical encoder 100 according to the first embodiment. The configuration of the optical encoder 100 will be described with reference to Figs. 1 and 2. Fig. 3 is a diagram explaining the process of determining and correcting an error location in a signal in the optical encoder 100 according to the first embodiment. The process of correcting the error location in the optical encoder 100 will be explained with reference to Fig. 3. Fig. 4 is a diagram explaining the operating principle of the optical encoder 100 according to the first embodiment, i.e., encoding in which an error correction code 16 is inserted into a position information code 10 by Manchester encoding.

[0014] The optical encoder 100 includes a rotating plate 1, a light emitting unit 3, a light receiving unit 4, a determining unit 8, and a correcting unit 9.

[0015] The rotary plate 1 is provided with a code pattern 2 that indicates the position information of the rotary plate 1.

[0016] The code pattern 2 has light-guiding sections 5 that guide the light α emitted from the light-emitting section 3 to the light-receiving section 4, and non-light-guiding sections 6 that block the light α emitted from the light-emitting section 3. The code pattern 2 has a pattern arrangement in which an M-sequence code is pseudo-randomly encoded, so that the light-guiding sections 5 and non-light-guiding sections 6 indicate position information.

[0017] In the first embodiment, the code pattern 2 is a pattern arrangement in which an M-sequence code representing position information using nine patterns is pseudo-randomly encoded to produce a Manchester code 17. Hereinafter, the pseudo-random encoding of an M-sequence code representing position information to produce a Manchester code 17 will be referred to as "Manchester encoding."

[0018] In the first embodiment, the position information code 10, which is an M-sequence code, and the position information code 10 that is Manchester-encoded will be described, but other random encoding methods may also be used. Furthermore, the code representing the position information is not limited to an M-sequence code, and any code other than an M-sequence code may be used as long as it contains position information. Like Manchester encoding, pseudo-random encoding involves inserting a regular code into a code containing position information. When Manchester encoding is performed, the code pattern 2 becomes a pattern arrangement in which an error correction code 16 is inserted. Conventionally, two lanes of code pattern 2 were provided on the rotating plate 1 to resolve position ambiguity. However, by inserting the error correction code 16 using Manchester encoding, only one lane of code pattern 2 is required, enabling the rotating plate 1 to be made smaller.

[0019] The light receiving unit 4 has 18 position detection light receiving elements 11 for outputting position information of the rotating plate 1 and four position correction light receiving elements 12 for outputting information to correct an incorrect position. Conventionally, when an M-sequence code is used, which represents one period of position using 9 bits, only 18 light receiving elements are used. Furthermore, to resolve position ambiguity, the light receiving elements are conventionally arranged in a two-row pattern. However, for example, if Manchester coding is used, a single row is sufficient because edge Ed can be detected. Note that edge Ed (edge ​​signal) is effective for detecting error locations. In this embodiment, a configuration of 18 position detection light receiving elements 11 and four position correction light receiving elements 12 for outputting information to correct an incorrect position is described, but the number of each light receiving element is not limited. The light receiving unit 4 converts the light guided to each light receiving element via the code pattern 2 into a binarized light receiving signal 7 of "0" or "1."

[0020] The determination unit 8 compares the position information code 10 and error correction code 16 in each code period 13 in the converted received light signal 7, and determines whether or not there is an error in the converted received light signal 7 by utilizing the reciprocal relationship described below. If there is an error in the received light signal 7, the error is identified. Furthermore, based on the output value of the received light signal 7, the determination unit 8 converts the Manchester code 17 into the position information code 10 and calculates output values ​​as a sequence 14 of position information for the rotating plate 1 and a sequence 15 of correction information. A calculation processing unit 30 (arithmetic processing section) is connected to the determination unit 8. The calculation processing unit 30 is a device that determines whether or not there is an error in the converted received light signal 7 by utilizing the reciprocal relationship described below.

[0021] The correction unit 9 corrects the output value that is judged to be incorrect by the judgment unit 8 by an exclusive logic operation.

[0022] Next, a means for outputting the position information code 10 will be described with reference to FIGS.

[0023] Light α emitted from the light emitting unit 3 is irradiated onto the rotating plate 1. The light α irradiates the code pattern 2 on the rotating plate 1. The light α that has irradiated the code pattern 2 is reflected by the light guiding unit 5 of the code pattern 2 and enters the light receiving unit 4.

[0024] In the light receiving section 4, the light α received by the position detection light receiving element 11 and the position correction light receiving element 12 is converted into a light receiving signal 7 of 0 / 1.

[0025] Next, the determination unit 8 determines whether there is an error in the received light signal 7. Specifically, the reciprocal relationship between the position information code 10 and the error correction code 16 in each code period 13 of the received light signal 7 is used to identify the error location in the converted received light signal 7. The reciprocal relationship will be described later. Then, the received light signal 7 is converted into the position information code 10.

[0026] If there is no error in the received light signal 7, the correction unit 9 outputs the position information code 10 as is without correcting it. If there is an error, the output value of the position information code 10 obtained by converting the error part of the received light signal 7 identified by the determination unit 8 is corrected by exclusive OR in the correction unit 9 and output. Correction when there is an error will be described later.

[0027] If there is no foreign matter mixed into the code pattern 2, the position information code 10 obtained by the correction unit 9 contains either the code value "1" or "0" for each code period 13, and is a code corresponding to the position information code of the code pattern 2.

[0028] Next, the operating principle of the optical encoder 100 according to the first embodiment, i.e., encoding in which the error correction code 16 is inserted into the position information code 10 by Manchester encoding, will be described with reference to Fig. 4. This operating principle is the principle of operation performed by the determination unit 8.

[0029] The error correction code 16 is compared with the position information code 10 in each code period 13 to assist in determining whether a false detection due to a foreign object has occurred within the code period 13. The code value changes depending on the position information code 10 in each code period 13. If the code value corresponding to the light-guiding section 5 of the position information code 10 is "1" and the code value corresponding to the non-light-guiding section 6 is "0," the error correction code 16 is inserted so that, using Manchester encoding, the code value corresponding to the light-guiding section 5 becomes "10" and the code value corresponding to the non-light-guiding section 6 becomes "01." At this time, in the code period 13, the inserted error correction code 16 establishes a reciprocal relationship with the adjacent position information code 10. The reciprocal relationship here means that the code values ​​within one period are not the same output value, such as "11" or "00." In each code period 13, an edge Ed is formed between the position information code 10 and the error correction code 16. When the position information code 10 is "1", the edge Ed is detected as a signal whose output value decreases from 1 to 0 in the code period 13. When the position information code 10 is "0", the edge Ed is detected as a signal whose output value increases from 0 to 1 in the code period 13.

[0030] With this configuration, even if the irradiated light is obstructed by the inclusion of foreign matter, it is possible to identify and correct the error in the light reception signal 7.

[0031] 5A and 5B are diagrams illustrating a method for detecting an error portion in the first embodiment when one portion of the light guiding portion 5 or the non-light guiding portion 6 of the Manchester-encoded code pattern 2 is covered with a foreign object, resulting in erroneous detection. Fig. 5A is a diagram illustrating a method for detecting an error in the determining unit 8 when a foreign object that acts as a reflecting object 18 has entered the non-light guiding portion 6 and guided light to the light receiving unit 4. Fig. 5B is a diagram illustrating a method for detecting an error portion in the determining unit 8 when a foreign object that acts as a light blocking object 19 has entered the light guiding portion 5 and blocked light.

[0032] The output value of the light receiving signal 7 obtained by converting light that has passed through the light-guiding section 5 in the light receiving section 4 is "1", and the output value of the light receiving signal 7 obtained by converting light that has passed through the non-light-guiding section 6 in the light receiving section 4 and outputting it is "0". The output value of the light receiving signal 7 obtained by converting light that has passed through the reflecting object 18 in the light receiving section 4 is "1". The output value of the light receiving signal 7 obtained by converting light that has passed through the light blocking object 19 in the light receiving section 4 is "0". Furthermore, if there is no erroneous detection due to a foreign object, a reciprocal relationship is always established within each code period 13 in this embodiment, and therefore the output value between code periods 13 is always "10" or "01".

[0033] In Figure 5A, reflecting object 18 causes the light receiving element to detect a large amount of light that should be zero (see the light intensity of the received light signal in Figure 5A), outputting "0" as "1" and resulting in an output value of "11" in code period 13. This state can be determined to be an error because the two pieces of signal information deviate from the reciprocal relationship. Therefore, the received light signal 7 in code period 13 that outputs "11" can be determined to be an error (see the error location in Figure 5A).

[0034] In Figure 5B, a light blocking object 19 prevents the light receiving element from detecting a sufficient amount of light, so "1" is output as "0", and the output value in code period 13 becomes "00". This state can be determined to be an error because the two pieces of signal information deviate from the reciprocal relationship. Therefore, the light receiving signal 7 in code period 13 that outputs "00" can be determined to be an error.

[0035] Although the case where one part of the Manchester-encoded code pattern 2 is covered by a foreign object has been described here, the error part can be determined in the same way when two or more parts of the code pattern 2 are covered by a foreign object. The determinations shown in Figures 5A and 5B are performed by the arithmetic processing device 30.

[0036] 6A and 6B are diagrams for explaining an example of a correction method by the correction unit 9. Fig. 6A is a diagram for explaining a case where the first output value of the sequence 15 of correction information is used, and Fig. 6B is a diagram for explaining a case where the second output value from the beginning of the sequence 15 of correction information is used.

[0037] FIG. 6A illustrates a method for correcting the third output value from the beginning of the sequence 14 of position information of the code pattern 2 when the determination unit 8 determines that the output value is incorrect.

[0038] 6A, the correction unit 9 acquires two output values ​​output based on the sequence of correction information 15 in addition to the nine output values ​​output based on the sequence of position information 14. The two output values ​​output based on the sequence of correction information 15 are output values ​​output from the light receiving unit 4, similar to the nine output values ​​output based on the sequence of position information 14. The two output values ​​output based on the sequence of correction information 15 are correction information for correcting at least one of the nine output values, which are position information indicating the position of the rotating plate 1.

[0039] In embodiment 1, the first output value in the sequence of correction information 15 is information for correcting one output value that is determined to be incorrect by the determination unit 8 from among the first, third from the top, fifth from the top, sixth from the top, seventh from the top, and eighth from the top output values ​​in the sequence of position information 14.

[0040] The first value is the exclusive OR of the first and third output values ​​from the top of the position information sequence 14. The second value is the exclusive OR of the first value and the fifth output value from the top of the position information sequence 14. The third value is the exclusive OR of the second value and the sixth output value from the top of the position information sequence 14. The fourth value is the exclusive OR of the third value and the seventh output value from the top of the position information sequence 14. The fifth value is the exclusive OR of the fourth value and the eighth output value from the top of the position information sequence 14. In this case, the first output value of the correction information sequence 15 is equal to the fifth value.

[0041] For example, if the first output value of the correction information sequence 15 is "0", the sum of the first, third from the top, fifth from the top, sixth from the top, seventh from the top, and eighth from the top output values ​​of the position information sequence 14 will be an even number.

[0042] On the other hand, if the output value of the correction information sequence 15 is "1", the sum of the output values ​​of the first, third from the top, fifth from the top, sixth from the top, seventh from the top, and eighth from the top of the position information sequence 14 is an odd number.

[0043] 6A, the first output value of correction information sequence 15 is "0." Meanwhile, the sum of the first, third, fifth, sixth, seventh, and eighth output values ​​of position information sequence 14 is "0" + "X" + "1" + "1" + "0" + "1" = "3+X." Because the first output value of correction information sequence 15 is "0," it is found that "3+X" is an even number, and it can be determined that "X" = "1."

[0044] 5A, it has already been determined that the third output value from the beginning of the positional information sequence 14 is incorrect. Therefore, the correction unit 9 outputs the third output value from the beginning of the positional information sequence 14 as "1" among the first, third, fifth, sixth, seventh, and eighth output values.

[0045] FIG. 6B illustrates a method for correcting the fourth output value from the beginning of the position information sequence 14 when the determining unit 8 determines that the output value is incorrect.

[0046] As shown in Figure 6B, the correction unit 9 obtains two output values ​​obtained based on the sequence of correction information 15 in addition to the nine output values ​​obtained based on the sequence of position information 14, as in the case shown in Figure 6A.

[0047] In embodiment 1, the second output value from the beginning of the sequence of correction information 15 is information for correcting one output value that is determined by the determination unit 8 to be possibly incorrect among the output values ​​output based on the second, fourth, sixth, seventh, eighth, and ninth output values ​​from the beginning of the sequence of position information 14.

[0048] The sixth value is the exclusive OR of the second and fourth output values ​​from the beginning of the position information sequence 14. The seventh value is the exclusive OR of the sixth value and the sixth output value from the beginning of the position information sequence 14. The eighth value is the exclusive OR of the seventh value and the seventh output value from the beginning of the position information sequence 14. The ninth value is the exclusive OR of the eighth value and the eighth output value from the beginning of the position information sequence 14. The tenth value is the exclusive OR of the ninth value and the ninth output value from the beginning of the position information sequence 14. In this case, the second output value from the beginning of the correction information sequence 15 is equal to the tenth value.

[0049] For example, if the second output value from the beginning of the correction information sequence 15 is "0", the sum of the output values ​​output based on the second, fourth, sixth, seventh, eighth, and ninth output values ​​from the beginning of the position information sequence 14 will be an even number.

[0050] On the other hand, if the second output value from the beginning of the position information sequence 14 is "1", the sum of the output values ​​output based on the second, fourth, sixth, seventh, eighth, and ninth values ​​from the beginning of the first sequence will be an odd number.

[0051] In FIG. 6B, the second output value from the beginning of the sequence of correction information 15 is “0.” Meanwhile, the sum of the second, fourth, sixth, seventh, eighth, and ninth output values ​​from the sequence of position information 14 is “1” + “X” + “0” + “0” + “0” + “1” = “2+X.” Because the first output value of the sequence of correction information 15 is “0,” it is determined that “2+X” is an even number, and it can be determined that “X” = “0.” Here, by using the above-described FIG. 5B, it has already been determined that the fourth output value from the beginning of the sequence of position information 14 is incorrect. Therefore, the correction unit 9 outputs the fourth output value from the beginning of the sequence of position information 14 as “0.”

[0052] (Embodiment 2) In the first embodiment, the code pattern 2 on the rotating plate 1 has been described as being Manchester-encoded by inserting the error correction code 16 into the position information code 10, but the code pattern 2 may be constructed by pseudo-random encoding using, for example, a differential Manchester code 20 shown in Fig. 7 instead of Manchester encoding. Pseudo-random encoding using the differential Manchester code 20 will hereinafter be referred to as "differential Manchester encoding."

[0053] The optical encoder 200 of the second embodiment has the same basic configuration as that of the first embodiment, and differs only in the code pattern 2 and the determination method in the determination unit 8. The other components and processing steps are the same as those of the first embodiment, and therefore will not be described again.

[0054] FIG. 7 is a diagram illustrating the operating principle of the optical encoder according to the second embodiment, specifically, a diagram illustrating how the code pattern 2 is differentially Manchester encoded (pseudo-randomly encoded using the differential Manchester code 20). Differential Manchester encoding has the following two characteristics. First, the code value always transitions from "0" to "1" or from "1" to "0" with each code period 13. That is, the code value changes from "1" to "0" or from "0" to "1" across the boundary between adjacent periods. Second, when the code value of the original position information code 10 is "1," the code value transitions to "10" or "01" in the middle of the code period 13 by differential Manchester encoding. On the other hand, when the code value of the position information code 10 is "0," the code value transitions to "11" or "00" in the middle of the code period 13 by differential Manchester encoding. That is, even if the code value of the position information code 10 continues to be the same value, the same output value does not continuously transition. For example, even if the code value of the position information code 10 is a series of "0"s, the output value obtained by differential Manchester encoding will not be a series of "11"s, "11". Regarding the second feature, as described above, in this embodiment, differential Manchester encoding is valid even when the conditions for "0" and "1" are reversed. Based on the above two features, for a code period 13 outputting "11" in FIG. 7, the two adjacent code periods 13 outputting "10" and "00" each function as an error correction code 16. The above-described relationship in which two adjacent code periods 13 for a given code period 13 function as error correction codes 16 is valid for all differential Manchester encoded code patterns 2. Note that because the signal changes between "1"s and "0"s or "0"s and "1"s across the boundary between adjacent periods, the signal change at the boundary between the adjacent periods can be considered an edge signal. In FIG. 7, this edge signal is referred to as edge Ed.

[0055] 8A and 8B are diagrams illustrating a method for detecting an error portion in the case where one portion of the light-guiding portion 5 or the non-light-guiding portion 6 of the differential Manchester-encoded code pattern 2 is covered with a foreign object, resulting in erroneous detection in the second embodiment. Fig. 8A is a diagram illustrating a method for detecting an error in the determining unit 8 when a foreign object that acts as a reflecting object 18 has entered the non-light-guiding portion 6 and guided light to the light-receiving unit 4. Fig. 8B is a diagram illustrating a method for detecting an error portion in the determining unit 8 when a foreign object that acts as a light-blocking object 19 has entered the light-guiding portion 5 and blocked light.

[0056] In Figure 8A, due to reflecting object 18, the light receiving element detects a large amount of light that should actually be zero (see the light intensity of the received light signal in Figure 8A), causing "0" to be output as "1", and the output value within code period 13 to become "01". In this state, the output value for the adjacent code period 13 is "11", and no transition in the code value accompanying the change in code period 13 is observed. Therefore, it is possible to determine that either or both of the received light signal 7 within code period 13 that outputs "01" and the adjacent "11" are errors (see the error locations in Figure 8A).

[0057] In Figure 8B, a light blocking object 19 prevents the light receiving element from detecting a sufficient amount of light (see the light intensity of the received signal in Figure 8B), so "1" is output as "0", and the output value in code period 13 becomes "00". In this state, the output value in the adjacent code period 13 is "10", and no transition in the code value accompanying the change in code period 13 is observed. Therefore, it is possible to determine that either or both of the received light signal 7 in the code period 13 that outputs "10" and the adjacent "00" is an error (see the error location in Figure 8B).

[0058] Here, the case where one part of the code pattern 2 is covered by a foreign object has been described, but the error part can also be determined in the same way when two or more parts of the code pattern 2 are covered by a foreign object.

[0059] FIG. 9 is a diagram illustrating a method for detecting an error location in the case where, in embodiment 2, a non-light-guiding section 6 and a light-blocking object 19 are mixed in the light-guiding section 5 during a code period 13 in which the non-light-guiding section 6 and the light-guiding section 5 are arranged in that order, causing the amount of light detected by the light-receiving element (see the light intensity of the received light signal in FIG. 9) to change and the output value within the code period 13 to be inverted.

[0060] Due to reflecting object 18 and light blocking object 19, the output value during code period 13, which should be "01," is inverted to "10," and the output value during three consecutive code periods 13 becomes "111000." Therefore, no transition in code value accompanying a change in code period 13 is observed between code period 13 outputting "11" and code period 13 outputting "10." Therefore, it is possible to determine that either or both of the received light signal 7 during code period 13 outputting "11" and the adjacent code period 13 outputting "10" are erroneous (see the error locations in FIG. 9). The determination shown in FIG. 9 is performed by calculation processing device 30.

[0061] Furthermore, a determining unit 8 converts the output value of the light receiving signal 7 into a position information code 10 based on the output value, and outputs it as a sequence 14 of position information for the rotary plate 1 and a sequence 15 of correction information.

[0062] If the determining unit 8 can identify the error location, the error location is corrected by the method explained in the first embodiment.

[0063] (Embodiment 3) In the embodiments up to now, methods of detecting errors using edge signals have been described, but in the third and subsequent embodiments, methods of identifying error locations without using edge signals will be described.

[0064] In the first embodiment, a configuration has been described in which one error correction code 16 is inserted into every other position information code 10 by Manchester encoding the code pattern 2 on the rotating plate 1. The above-described configuration may also be a configuration in which two error correction codes 16 are inserted into every third position information code 10.

[0065] The optical encoder 300 of the third embodiment has the same basic configuration as that of the first embodiment, and differs only in the code pattern 2 and the determination method in the determination unit 8. The other components and processing steps are the same as those of the first embodiment, and therefore will not be described again.

[0066] FIG. 10 is a diagram showing the operating principle of an optical encoder 300 according to the third embodiment, i.e., a diagram showing encoding in which two error correction codes 16 are inserted into every third position information code 10 (see repetition code 24 in FIG. 10 ). Here, a code having the same output value as two consecutive position information codes 10 before conversion is inserted as the error correction code 16, and a total of four codes, consisting of two consecutive position information codes 10 and two error correction codes 16, form one code period 13. That is, in the third embodiment, the code period is twice as long as in the first embodiment. Note that the repetition code 24 corresponds to code pattern 2.

[0067] In the encoding described above, the inserted error correcting code 16 establishes a repeating relationship with the adjacent position information code 10 within the code period 13. The repeating relationship here means that the position information code 10 and the error correcting code 16 repeat the same output value, such as "0000," "1010," "0101," and "1111," within each code period 13. Since only the four types of code patterns described above are output, it is possible to calculate the position information by recognizing the four types of code patterns described above.

[0068] 11A and 11B are diagrams illustrating a method for detecting an error portion in the case where one portion of the light-guiding portion 5 or the non-light-guiding portion 6 is covered with a foreign object, resulting in erroneous detection, in the third embodiment. Fig. 11A is a diagram illustrating a method for detecting an error in the determining portion 8 when a foreign object that becomes a reflecting object 18 has entered the non-light-guiding portion 6 and guided light to the light-receiving portion 4. Fig. 11B is a diagram illustrating a method for detecting an error portion in the determining portion 8 when a foreign object that becomes a light-blocking object 19 has entered the light-guiding portion 5 and blocked light.

[0069] If there is no false detection due to a foreign object, a repeating relationship is always established within each code period 13, and therefore the output value within each code period 13 will always be either "0000", "1010", "0101", or "1111".

[0070] In FIG. 11A, due to reflector 18, the light receiving element detects a large amount of light that should be zero (see the light intensity of the received light signal in FIG. 11A), causing "0" to be output as "1", and the output value in code period 13 to become "1011". This state can be determined to be an error because the four pieces of signal information deviate from the repeating relationship. Therefore, the received light signal 7 in code period 13 that outputs "1011" can be determined to be an error (see the error location in FIG. 11A). The determinations shown in FIGS. 11A and 11B are performed by the arithmetic processing device 30.

[0071] In Figure 11B, a light blocking object 19 prevents the light receiving element from detecting a sufficient amount of light (see the light intensity of the received signal in Figure 11B), so "1" is output as "0", and the output value in code period 13 becomes "1000". This state can be determined to be an error because the two pieces of signal information deviate from the repeating relationship (see the error location in Figure 11B). Therefore, the received light signal 7 in code period 13, which outputs "1000", can be determined to be an error.

[0072] Here, the case where one part of the code pattern 2 is covered by a foreign object has been described, but the error part can also be determined in the same way when two or more parts of the code pattern 2 are covered by a foreign object.

[0073] Furthermore, a determining unit 8 converts the output value of the light receiving signal 7 into a position information code 10 based on the output value, and outputs it as a sequence 14 of position information for the rotary plate 1 and a sequence 15 of correction information.

[0074] If the determining unit 8 can identify the error location, the error location is corrected by the method explained in the first embodiment.

[0075] (Fourth embodiment) In the third embodiment, a configuration in which two error correction codes 16 are inserted for every third position information code 10 has been described, but a configuration in which one error correction code 16 is inserted for every third position information code 10 may also be used.

[0076] The optical encoder 400 of the fourth embodiment has the same basic configuration as that of the first embodiment, and differs only in the code pattern 2 and the determination method in the determination unit 8. The other components and processing steps are the same as those of the first embodiment, and therefore will not be described again.

[0077] FIG. 12 is a diagram illustrating the operating principle of an optical encoder 400 according to the fourth embodiment, that is, a diagram illustrating encoding in which one error correction code 16 is inserted into every third position information code 10 (see the repetition code 25 after conversion in FIG. 12). Here, one error correction code 16 is inserted, which outputs a value corresponding to the value output from two consecutive position information codes 10 before conversion. This is encoding in which three codes, consisting of two consecutive position information codes 10 and one error correction code 16, form one code period 13. Note that the repetition code 25 corresponds to code pattern 2.

[0078] The inserted error correction code 16 establishes a correspondence relationship with two position information codes 10 within each code period 13. Here, the correspondence relationship is such that when the position information code 10 is "11" or "10", "1" is inserted as the error correction code 16. When the position information code 10 is "01" or "00", "0" is inserted as the error correction code 16. Therefore, within each code period 13, the position information code 10 and the error correction code 16 always indicate one of the output values ​​"111", "101", "010", or "000". Because only the four types of code patterns mentioned above are output, it is possible to calculate position information by recognizing the four types of code patterns mentioned above.

[0079] 13A and 13B are diagrams illustrating a method for detecting an error portion in the case where one portion of the light-guiding portion 5 or the non-light-guiding portion 6 is covered with a foreign object, resulting in erroneous detection, in the fourth embodiment. Fig. 13A is a diagram illustrating a method for detecting an error when a foreign object that becomes a reflecting object 18 has entered the non-light-guiding portion 6 and guided light to the light-receiving portion 4. Fig. 13B is a diagram illustrating a method for detecting an error portion in the determining portion 8 when a foreign object that becomes a light-blocking object 19 has entered the light-guiding portion 5 and blocked light.

[0080] If there is no false detection due to a foreign object, a correspondence relationship is always established within each code period 13, and therefore the output value within each code period 13 will always be either "111", "101", "010", or "000".

[0081] In Figure 13A, reflecting object 18 causes the light receiving element to detect a large amount of light, which should be zero (see the light intensity of the received light signal in Figure 13A), and "0" is output as "1", resulting in the output value in code period 13 being "100". This state can be determined to be an error because the three pieces of signal information deviate from their corresponding relationship. Therefore, the received light signal 7 in code period 13, which outputs "100", can be determined to be an error (see the error location in Figure 13A).

[0082] In FIG. 13B, a sufficient amount of light cannot be detected by the light receiving element due to a light blocking object 19, so "1" is output as "0" (see the light intensity of the received signal in FIG. 13B), and the output value during code period 13 becomes "100." This state can be determined to be an error because the three pieces of signal information deviate from the reciprocal relationship. Therefore, the received light signal 7 during code period 13 that outputs "100" can be determined to be an error (see the error location in FIG. 13B). The determinations shown in FIGS. 13A and 13B are performed by the arithmetic processing device 30.

[0083] Here, the case where one part of the code pattern 2 is covered by a foreign object has been described, but the error part can also be determined in the same way when two or more parts of the code pattern 2 are covered by a foreign object.

[0084] Furthermore, a determining unit 8 converts the output value of the light receiving signal 7 into a position information code 10 based on the output value, and outputs it as a sequence 14 of position information for the rotary plate 1 and a sequence 15 of correction information.

[0085] If the determining unit 8 can identify the error location, the error location is corrected by the method explained in the first embodiment.

[0086] In the first embodiment, a configuration in which one error correction code 16 is inserted for one position information code 10 has been described. In the third embodiment, a configuration in which two error correction codes 16 are inserted for two position information codes 10 has been described. In the fourth embodiment, a configuration in which one error correction code 16 is inserted for two position information codes 10 has been described. The numbers of position information codes 10 and the corresponding error correction codes 16 are not limited to the above four forms. For example, the arrangement of code pattern 2 may be an arrangement in which Y (Y is a natural number) error correction codes 16 are inserted every X (X is a natural number) position information codes 10 in the position information data string.

[0087] (Embodiment 5) The light receiving unit 4 in the first, second, third, and fourth embodiments is composed of a position detection light receiving element 11 that outputs position information and a position correction light receiving element 12 that outputs error correction information. However, it is sufficient that the light receiving element can output position information and error correction information. For example, an image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) sensor or a CCD (Charge Coupled Device) sensor, each having an area for outputting position information and an area for outputting error correction information, may be used instead of the light receiving element. The first, second, third, fourth, and fourth embodiments, as well as the present embodiment, can be applied to either a reflective or transmissive optical encoder. In a transmissive optical encoder, the light emitting unit 3, the rotating plate 1, and the light receiving unit 4 are arranged in a transmissive optical configuration, and the light guiding unit 5 and the non-light guiding unit 6 are configured as a transmissive unit and a non-transmissive unit, respectively. In the case of a reflective optical encoder, the light emitting unit 3, the rotating plate 1, and the light receiving unit 4 are arranged in a reflective optical configuration, and the light guiding unit 5 and the non-light guiding unit 6 are configured as a reflective unit and a non-reflective unit, respectively. As long as the transmissive and reflective optical encoders are configured as described above, there are no limitations on the materials and manufacturing methods for each component.

[0088] (Sixth embodiment) In the above first to fifth embodiments, a rotary encoder has been described, but the present invention is not limited to rotary encoders and can also be applied to linear encoders shown in FIGS. 14A and 14B.

[0089] Fig. 14A is a schematic diagram showing an example of an optical encoder 500 according to the sixth embodiment. Fig. 14B is a perspective view of a moving body 23 of the optical encoder 500 according to the sixth embodiment. The difference from the first embodiment is that a moving body 23 is used instead of the rotating body 21.

[0090] The moving body 23 moves linearly. A code pattern 2 is provided on the surface of the moving body 23. The code pattern 2 has a straight strip shape. The light emitting unit 3 and the light receiving unit 4 are provided on the main surface of the fixed unit 22, facing the code pattern 2. The determination unit 8 and the correction unit 9 are provided on the surface of the fixed unit 22 opposite to the main surface on which the light emitting unit 3 and the light receiving unit 4 are provided. The light emitting unit 3 has, for example, an LED (Light Emitting Diode). The light receiving unit 4 has, for example, a light receiving element. Light α emitted from the LED of the light emitting unit 3 irradiates the code pattern 2, and the light α reflected by the code pattern 2 and returned is received by the light receiving element of the light receiving unit 4. The light receiving unit 4, the determination unit 8, and the correction unit 9 are electrically connected. The determination unit 8 has, for example, an electronic circuit. The determination unit 8 processes a signal of the light α received by the light receiving element of the light receiving unit 4. The correction unit 9 includes, for example, an electronic circuit and processes the signal from the determination unit 8.

[0091] The operation of the optical encoder 500 according to the sixth embodiment is similar to the operation of the optical encoder 100 according to the first embodiment.

[0092] It goes without saying that this embodiment can be applied to either a reflective or transmissive optical encoder, similar to embodiments 1 to 5. As long as a transmissive or reflective optical encoder is configured with the above-described structure, there are no limitations on the materials and manufacturing methods for each structure. [Industrial Applicability]

[0093] The encoder according to the present disclosure can be used to detect the rotation of the rotating shaft of a motor that rotates a load, etc. The encoder according to the present disclosure can also be used to detect the position of an object that moves linearly. [Explanation of symbols]

[0094] 1 Rotating plate 2 Code Pattern 3 Light irradiation unit 4 Light receiving section 5 Light guide section 6 Non-light-guiding section 7. Light receiving signal 8 Judgment section 9. Corrections Department 10 Location information code 11 Position detection light receiving element 12 Position correction light receiving element 13 code period 14 Location information sequence 15 Correction information sequence 16 Error Correcting Codes 17 Manchester Code 18 Reflective objects 19 Shading 20 Differential Manchester Code 21 Rotating body 22 Fixed part 23 Mobile 24, 25 repeat code 30 Processing unit 100, 200, 300, 400, 500 Optical Encoder SH rotation axis

Claims

1. a moving plate having a code pattern having position information; a light irradiation unit that irradiates the code pattern with light; a light receiving unit that receives light that has been irradiated from the light irradiating unit and passed through the code pattern, the code pattern is composed of a light guiding portion that guides the light irradiated from the light irradiating portion to the light receiving portion, and a non-light guiding portion that does not guide the light irradiated from the light irradiating portion to the light receiving portion, The code pattern array is an array in which an error correction code is inserted into a position information data string, the light receiving unit includes a position detection light receiving element that reads the arrangement of the code pattern, and a position correction light receiving element that outputs information for correcting an error, The arrangement of the code pattern is such that Y error correction codes are inserted every X position information codes of the position information data string. Encoder.

2. The code pattern is configured on a rotating plate. The encoder of claim 1 .

3. a determination unit that determines whether or not there is an error in the position information output by the light receiving unit; a correction unit that corrects the result determined to be an error by the determination unit, 3. The encoder according to claim 1 or 2.

4. the light receiving unit includes an image sensor having a position detection area that outputs position information of the code pattern and a position correction area that outputs information for correcting errors; The encoder according to any one of claims 1 to 3.

Images