Position correction method for optical encoder capable of correcting relative position of components

Abstract

An optical encoder capable of correcting the relative position of an element comprises a coding medium, a detector package and a memory. The detector package comprises a photodiode array and two correction photodiodes relative to the coding medium. The memory records a correction pattern related to the output signals of the two correction photodiodes when the coding medium and the detector package are located at a standard operating position. When the coding medium and the detector package are not located at the standard operating position, the relative position is corrected by adjusting the current relative position of the coding medium and the detector package so that the current pattern related to the output signals of the two correction photodiodes is the same as the correction pattern.

Description

Technical Field

[0001] The present invention relates to an optical encoder, and more particularly to an optical encoder for calibrating the relative distance between components by pre-stored calibration patterns and a position calibration method thereof. Background Art

[0002] Please refer to Figure 1 , which is a block diagram of a conventional optical encoder, the optical encoder comprises a light source 11, a coding medium 13, a photodiode 15 and a processing circuit 17. The photodiode 15 detects the light emitted by the light source 11 for illuminating the coding medium 13. The transimpedance amplifier (TIA) outputs four signals A, A', B and B' with a phase difference of 90 degrees in sequence. The processing circuit 17 compares the signals A, A', B and B' and generates two output signals CHA and CHB, as shown in FIG. Figure 2 shown.

[0003] Figure 2 The timing diagram of the output signals CHA and CHB is shown. Figure 2 As can be seen from FIG. 1 , since the combination of the voltage levels of the output signals CHA and CHB has four states in one cycle of the coding medium 13 , it can be used to represent four positions of the coding medium 13 . Figure 2 As shown, the four states each have a phase interval of 90 degrees.

[0004] Please refer to Figure 3 , which is Figure 1 The relative positions of the components are shown in the figure. Figure 2 In the timing diagram shown, the light source 11, the coding medium 13 and the photodiode 15 must be arranged at predetermined positions on the X-axis, Y-axis and Z-axis in space. However, during assembly and installation, at least one of the light source 11, the coding medium 13 and the photodiode 15 may not be located at the predetermined position, resulting in a positional offset in at least one axial direction, which will cause the phase interval corresponding to the four states to be greater than or less than 90 degrees, such as Figure 4 As shown, the position determination accuracy is reduced. This reduction in accuracy is more obvious in optical encoders using the internal difference technique.

[0005] Although the above-mentioned problem of reduced precision can be reduced through more rigorous assembly and assembly control, it requires considerable cost.

[0006] In view of this, a low-cost optical encoder capable of calibrating the relative positions of components and a position calibration method thereof are needed. Summary of the invention

[0007] The present invention provides an optical encoder including two additional correction diodes, which records in advance the correction patterns related to the output signals of the two correction diodes when each element of the optical encoder is located at a standard operating position, so as to serve as a basis for position correction.

[0008] The present invention also provides a method for position correction of an optical encoder. Position correction can be completed by adjusting the current pattern related to the output signals of the two correction diodes to be the same as the pre-stored reference pattern.

[0009] The present invention provides an optical encoder including a light detector. The light detector is used to receive modulated light from a coding medium, and includes a detection diode array, a first photodiode, and a second photodiode. The detection diode array is arranged relative to the coding medium. The first photodiode and the second photodiode are respectively located on both sides of the detection diode array. Each of the first photodiode and the second photodiode has a trapezoidal detection surface.

[0010] The present invention also provides a method for position correction of an optical encoder including a coding medium and a light detector. The method comprises the following steps: determining a reference pattern in advance according to reference output signals of the first photodiode and the second photodiode; determining a current pattern according to current output signals of the first photodiode and the second photodiode; and adjusting the relative position of the coding medium and the light detector so that the current pattern is the same as the reference pattern.

[0011] The present invention also provides a position correction method for an optical encoder including a coding medium and a light detector. The position correction method includes the following steps: predetermining a plurality of correction patterns according to the reference output signals of the first photodiode and the second photodiode, wherein one of the plurality of correction patterns is a reference pattern in which the coding medium and the light detector are located at a predetermined relative position, and the other plurality of correction patterns are secondary reference patterns in which the coding medium and the light detector are located at different relative positions; step A: determining a current pattern according to the current output signals of the first photodiode and the second photodiode; step B: comparing the current pattern with the plurality of secondary reference patterns to determine the offset direction of the coding medium and the light detector; and step C: moving at least one of the coding medium and the light detector in the opposite direction of the offset direction, and repeating steps A to C until the current pattern is equal to the reference pattern.

[0012] In order to make the above and other purposes, features and advantages of the present invention more obvious, the following will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, the same components are represented by the same symbols, which are hereby described together. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a block diagram of a known optical encoder;

[0014] Figure 2 yes Figure 1 A timing diagram of the output signal of the optical encoder;

[0015] Figure 3 is a schematic diagram of a known optical encoder;

[0016] Figure 4 yes Figure 3 Schematic diagram of output signals when the component positions of the optical encoder are not configured correctly;

[0017] Figure 5A is a schematic diagram of an optical encoder according to an embodiment of the present invention;

[0018] Figure 5B is a schematic diagram of a coding medium and a light detector of an optical encoder according to an embodiment of the present invention;

[0019] Figure 6 is a schematic diagram of a reference pattern recorded by an optical encoder according to an embodiment of the present invention;

[0020] Figures 7A-7H is a schematic diagram of other secondary reference patterns recorded by an optical encoder according to some embodiments of the present invention;

[0021] Fig. 8A is a schematic diagram of a coding medium and a light detector of an optical encoder according to another embodiment of the present invention;

[0022] Figure 8B yes Fig. 8A A schematic diagram of a reference pattern recorded by an optical encoder;

[0023] Fig. 9A is a schematic diagram of a coding medium and a light detector of an optical encoder according to yet another embodiment of the present invention;

[0024] Fig. 9B yes Fig. 9A A schematic diagram of a reference pattern recorded by an optical encoder;

[0025] Fig. 10A is a schematic diagram of a coding medium and a light detector of an optical encoder according to yet another embodiment of the present invention;

[0026] Fig. 10B yes Fig. 10A A schematic diagram of a reference pattern recorded by an optical encoder;

[0027] Fig.11 is a schematic diagram of a coding medium and a light detector of an optical encoder according to yet another embodiment of the present invention;

[0028] Fig.12 is a flow chart of a method for position correction of an optical encoder according to an embodiment of the present invention; and

[0029] Fig.13 is a flow chart of a method for calibrating a position of an optical encoder according to another embodiment of the present invention.

[0030] Description of Reference Numerals

[0031] 500 Optical Encoder

[0032] 51 Light Source

[0033] 53 Encoded Media

[0034] 531 Reflector

[0035] 533 Non-reflective part

[0036] 55 Photodetector

[0037] 57 Transimpedance Amplifier

[0038] 59 Processing Circuit

[0039] A', B', NA', NB' detection diodes

[0040] APD+ First Photo Diode

[0041] APD - Secondary Photo Diode DETAILED DESCRIPTION

[0042] The optical encoder of the embodiment of the present invention is used to generate channel A and channel B (for example, referring to Figure 2 ) are provided on both sides of the diode array for detecting the output signal of the optical encoder, and no specially designed code slits are required. As long as the reference pattern of the output signals of the two correction diodes when each element of the optical encoder is in the standard position is recorded in advance, and during assembly and installation, the relative positions of the elements are adjusted so that the output signals of the two correction diodes produce the same current pattern as the pre-stored reference pattern, the element position can be corrected.

[0043] Please refer to Figure 5A , which is a schematic diagram of an optical encoder 500 according to an embodiment of the present invention. The optical encoder 500 includes a light source 51, a coding medium (which may be a coding disc or a coding tape according to different applications) 53, a light detector 55, a transimpedance amplifier (TIA) 57, and a processing circuit 59. The processing circuit 59 is, for example, an application specific integrated circuit (ASIC) or a digital signal processor (DSP). According to different embodiments, the light source 51 and the light detector 55 may be located in the same package or in different packages.

[0044] The light source 51 may be a coherent light source, a partially coherent light source or a non-coherent light source, and is used to project light with a recognizable spectrum toward the coding medium 53. The light source 51 is, for example, an infrared light emitting diode or an infrared laser diode, but is not limited thereto.

[0045] Please also refer to Figure 5B As shown, in the reflective optical encoder, the code of the coding medium 53 includes a reflective portion (or a reflective area) and a non-reflective portion (or a non-reflective area). For example, the blank area 531 represents the reflective portion and the oblique area 533 represents the non-reflective portion, or the reverse arrangement can be used. The reflective portion 531 is used to reflect the emitted light from the light source 51 toward the light detector 55. The non-reflective portion 533 is, for example, a hollow area, and can also be coated with a light-absorbing material, as long as most of the emitted light from the light source 51 is not reflected, and there is no specific limitation. In the transmissive optical encoder, the blank area 531 represents the reflective portion and the oblique area 533 represents the transmissive portion, or the reverse arrangement can be used.

[0046] like Figure 5B As shown, the blank areas 531 and the oblique line areas 533 are alternately arranged to form the code of the coding medium 53 for modulating the incident light.

[0047] That is, the coding medium 53 can be reflective or transmissive, and has a predetermined pattern coding thereon for generating modulated light when the emitted light from the light source 51 is reflected or transmitted. The coding medium 53 can perform linear motion, curvilinear motion, or rotational motion, depending on different applications. During operation, the coding medium 53 generates a relative displacement relative to the light source 51 and the light detector 55, and the predetermined pattern coding performs light modulation on the emitted light.

[0048] In the present invention, the photodetector 55 includes a detection diode array, a first photodiode APD+ and a second photodiode APD-.

[0049] The detector diode array contains multiple photodiodes (e.g. Figure 5B A', B', NA', NB') are shown relative to the coding configuration of the coding medium 53 to be able to receive modulated light, which is formed by modulating the emitted light from the light source 51. For example, when the coding medium 53 is a reflective structure, the light source 51 and the light detector 55 are arranged on the same side of the coding medium 53; and when the coding medium 53 is a transmissive structure, the light source 51 and the light detector 55 are arranged on opposite sides of the coding medium 53.

[0050] After receiving the modulated light, multiple photodiodes A', B', NA', and NB' generate detection signals with phase differences of 90 degrees in sequence through the transimpedance amplifier 57, for example, the first signal A'=sin+, the second signal B'=cos+, the third signal NA'=sin-, and the fourth signal NB'=cos-; wherein the first signal sin+ is a sine signal, the second signal cos+ is a cosine signal, the third signal sin- is 180 degrees out of phase with the first signal sin+, and the fourth signal cos- is 180 degrees out of phase with the second signal cos+, but the present invention is not limited to this.

[0051] The operating principle of the transimpedance amplifier 57 is well known and will not be described in detail here.

[0052] The processing circuit 59 processes the output signals generated by the plurality of photodiodes A', B', NA', and NB' (for example, performing a differential operation between A' and NA' and between B' and NB') to generate a signal such as: Figure 2 The two output signals CHA and CHB.

[0053] Please refer to Figure 5B The optical encoder 500 of the embodiment of the present invention further includes two correction diodes (e.g., a first photodiode APD+ and a second photodiode APD-) respectively disposed on both sides of the detection diode array. Each of the first photodiode APD+ and the second photodiode APD- has a trapezoidal detection surface. The transimpedance amplifier 57 also converts and amplifies the photocurrents of the first photodiode APD+ and the second photodiode APD- to generate a voltage signal.

[0054] For example, the structures of the first photodiode APD+ and the second photodiode APD- are the same as the structures of the plurality of photodiodes A', B', NA', and NB', and a portion (e.g., a triangle) of the detection surfaces of the first photodiode APD+ and the second photodiode APD- is shielded by an opaque material, and the incident light can only be detected by the correction diode through the trapezoidal detection surface. In one embodiment, the width d2 of the detection surface (e.g., a rectangular area filled with dots) of each photodiode A', B', NA', and NB' of the detection diode array and the width d2 of the trapezoidal detection surface of the first photodiode APD+ and the second photodiode APD- are equal to half of the width d1 of the reflective portion 531 and the non-reflective portion 533.

[0055] In one embodiment, the optical encoder 500 is a single track structure, and the detection diode array and the first photodiode APD+ and the second photodiode APD- are located in the same track, wherein the same track means that the positions in the Y-axis direction are substantially the same. In a multi-track structure, the first photodiode APD+ and the second photodiode APD- can be located in the same track with some detection diodes and in different tracks with other detection diodes (such as index diodes, but not limited to), depending on different applications.

[0056] It is understandable that Figure 5B In order to illustrate the relative position of the light detector 55 and the code of the coding medium 53, the detection diode array and the first photodiode APD+ and the second photodiode APD- are drawn on the side of the code of the coding medium 53. In fact, the light detector 55 is located in the height direction (i.e., the Z-axis direction) of the coding medium 53. Figure 5A shown.

[0057] In one embodiment, the first photodiode APD+ is connected to the first side of the detection diode array (eg Figure 5B The first distance 3d1 (in the left side) is equal to the second photodiode APD- to the second side of the detection diode array (eg Figure 5B When the second photodiode APD- is opposite to one of the non-reflective portions 533 (for example, by moving the coding medium 53), the first photodiode APD+ is opposite to one of the reflective portions 531 so that the output signal of the first photodiode APD+ is maximum, and the output signal of the second photodiode APD- is minimum, or vice versa.

[0058] Figure 5B In the embodiment, the long sides of the two parallel sides of the trapezoidal detection surfaces of the first photodiode APD+ and the second photodiode APD- (i.e., the right side of the trapezoidal detection surface of the first photodiode APD+ and the left side of the trapezoidal detection surface of the second photodiode APD-) face the detection diode array; and the inclined sides of the trapezoidal detection surfaces of the first photodiode APD+ and the second photodiode APD- face different directions, for example, the inclined side of the trapezoidal detection surface of the first photodiode APD+ faces downward while the inclined side of the trapezoidal detection surface of the second photodiode APD- faces upward.

[0059] The output photocurrents of the first photodiode APD+ and the second photodiode APD- are also converted and amplified into voltage signals by the transimpedance amplifier 53. The processing circuit 59 normalizes the voltage signal related to the first photodiode APD+ (for example, dividing the voltage signal by the maximum voltage signal generated by the first photodiode APD+ or by the sum of the voltage signals generated by the first photodiode APD+ and the second photodiode APD-) and uses the normalized voltage signal as the output signal of the first photodiode APD+; the processing circuit 59 normalizes the voltage signal related to the second photodiode APD- (for example, dividing the voltage signal by the maximum voltage signal generated by the second photodiode APD- or by the sum of the voltage signals generated by the first photodiode APD+ and the second photodiode APD-) and uses the normalized voltage signal as the output signal of the second photodiode APD-. In this way, the following can be formed. Figure 6 The reference pattern shows the relationship between the output signal values ​​of the two correction diodes and is recorded in the memory of the optical encoder 500, such as EEPROM, random access memory (RAM) or flash memory, but not limited thereto.

[0060] More specifically, the optical encoder 500 further includes a memory for recording in advance when the encoding medium 53 and the light detector 55 (or a package including the light detector 55) are located at a predetermined relative position, for example Figure 6 Shown in the figure is a reference pattern related to the reference output signals of the first photodiode APD+ and the second photodiode APD- at position (X, Y, Z), wherein the reference output signal refers to the output signal obtained before leaving the factory.

[0061] In another embodiment, the memory of the optical encoder 500 is also used to record in advance a plurality of sub-reference patterns related to the reference output signals of the first photodiode APD+ and the second photodiode APD- when the coding medium 53 and the photodetector 55 (or the package including the photodetector 55) are located at different relative positions, wherein the sub-reference patterns are obtained when the coding medium 53 and the photodetector 55 are located at non-standard relative positions (i.e., non-predetermined relative positions) before leaving the factory. The sub-reference patterns are used when the relative positions are adjusted step by step, and an example is given below.

[0062] In the present invention, the relative position of the coding medium 53 and the photodetector 55 (or the package including the photodetector 55) includes the tangential direction (such as Figure 5A X-axis) position, axial direction (such as Figure 5A Y-axis) position and height direction (such as Figure 5A The Z-axis position of Fig. 7A and Figure 7BA secondary reference pattern showing a case where the relative positions of the coding medium 53 and the light detector 55 have a positional offset of ±b in the height direction; Figure 7C A secondary reference pattern showing the relative positions of the coding medium 53 and the light detector 55 having a position offset of -a in the tangential direction and the axial direction; Fig.7D and Fig. 7E A secondary reference pattern showing a case where the relative positions of the coding medium 53 and the light detector 55 have a positional offset of -a in the tangential direction and the axial direction and a positional offset of ±b in the height direction; Figure 7F A secondary reference pattern showing the relative positions of the coding medium 53 and the light detector 55 having a position offset of +a in the tangential direction and the axial direction; Figure 7G and Figure 7H The sub-reference pattern shows a case where the relative positions of the encoding medium 53 and the photodetector 55 have a positional offset of +a in the tangential direction and the axial direction and a positional offset of ±b in the height direction.

[0063] It must be noted that the reference pattern and multiple sub-reference patterns stored in the memory are not limited to Figure 6 and 7A to 7H As shown, when different reflective conditions and total indicator runout (TIR) ​​of the coded medium 53 are considered, the generated reference pattern and the plurality of sub-reference patterns will be different.

[0064] Please refer to Fig. 8A , which is a schematic diagram of the encoding of the encoding medium 53 and the light detector 55 of the optical encoder 500 according to another embodiment of the present invention. Fig. 8A and Figure 5B The difference is that Fig. 8A In the embodiment, the orientation direction of the inclined sides of the trapezoidal detection surfaces of the first photodiode APD+ and the second photodiode APD- is Figure 5B Different, the configuration of other components is the same as Figure 5B The same, so no further elaboration is given here. Figure 8B yes Fig. 8A As mentioned above, in other embodiments, the optical encoder 500 may also record a secondary reference pattern in which the encoding medium 53 and the light detector 55 (or the package including the light detector 55) are located at different relative positions. Figure 7A-7H shown.

[0065] Please refer to Fig. 9A , which is a schematic diagram of the encoding of the encoding medium 53 and the light detector 55 of the optical encoder 500 according to yet another embodiment of the present invention. Fig. 9A and Figure 5B The difference is that Fig. 9AIn the embodiment, the orientation direction of the inclined side of the trapezoidal detection surface of the first photodiode APD+ is Figure 5B The inclined sides of the trapezoidal detection surfaces of the first photodiode APD+ and the second photodiode APD- are oriented in the same direction, and the configuration of other components is the same as Figure 5B The same, so no further elaboration is given here. Fig. 9B yes Fig. 9A As mentioned above, in other embodiments, the optical encoder 500 may record a secondary reference pattern in which the encoding medium 53 and the light detector 55 (or a package including the light detector 55) are located at different relative positions. Figure 7A-7H shown.

[0066] Please refer to Fig. 10A , which is a schematic diagram of the encoding of the encoding medium 53 and the light detector 55 of the optical encoder 500 according to yet another embodiment of the present invention. Fig. 10A and Figure 5B The difference is that Fig. 10A In the embodiment, the orientation direction of the inclined sides of the trapezoidal detection surfaces of the first photodiode APD+ and the second photodiode APD- is Figure 5B different. Fig. 10A In the embodiment, the long sides of the two parallel sides of the trapezoidal detection surface of the first photodiode APD+ face the detection diode array, while the short sides of the two parallel sides of the trapezoidal detection surface of the second photodiode APD- face the detection diode array, and the configuration of other components is the same as Figure 5B The same, so no further elaboration is given here. Fig. 10B yes Fig. 10A As mentioned above, in other embodiments, the optical encoder 500 may record a secondary reference pattern in which the encoding medium 53 and the light detector 55 (or a package including the light detector 55) are located at different relative positions. Figure 7A-7H shown.

[0067] Although the above embodiment is described by taking the example that the distances between the two correction diodes and the two opposite sides of the detection diode array are the same (for example, both are 3d1) and the widths of the two correction diodes (for example, both are d2) are equal to half of the widths of the reflection portion 531 and the non-reflection portion 533 (for example, both are d1), the present invention is not limited thereto. Fig.11 As shown, the first distance d from the first photodiode APD+ to the first side of the detection diode array is not equal to the second distance d' from the second photodiode APD- to the second side of the detection diode array; and the width W of the trapezoidal detection surface of the first photodiode APD+ and the second photodiode APD- is equal to the width d1 of the reflective portion 531 and the non-reflective portion 533. As long as the correction pattern related to the output signal of the first photodiode APD+ and the second photodiode APD- can be recorded in advance, for example Figure 6 , 7A to 7H , that is, the purpose of position correction during assembly and assembly can be achieved.

[0068] also, Figure 5B , Fig. 8A , Fig. 9A , Fig. 10A and Fig.11 In the embodiment, the height H of the correction diode is equal to the height h1 of the detection diode array, but the present invention is not limited thereto. In other embodiments, the height H may not be equal to h1.

[0069] Please refer to Fig.12 As shown, it is a flow chart of the position correction method of the optical encoder 500 of an embodiment of the present invention, comprising the following steps: pre-determining a reference pattern based on the reference output signals of the first photodiode and the second photodiode (step S121); determining a current pattern based on the current output signals of the first photodiode and the second photodiode (step S123); and adjusting the relative position of the encoding medium and the light detector so that the current pattern is the same as the reference pattern (step S125).

[0070] Step S121: Before leaving the factory, the coding medium 53 and the photodetector 55 are first configured to be located at a standard relative position (i.e., a predetermined relative position) to obtain the output signals of the first photodiode APD+ and the second photodiode APD-. Because they are used as the basis for position correction, they are referred to as reference output signals in this specification. As mentioned above, the reference output signal is a voltage signal generated after the photocurrent output by the first photodiode APD+ and the second photodiode APD- is converted and amplified by the transimpedance amplifier 57. After normalizing the voltage signal, the relationship between the first normalized voltage signal (e.g., the normalized APD+ in the figure) and the second normalized voltage signal (e.g., the normalized APD- in the figure) can be obtained as a reference pattern, for example Figure 6 , Figure 8B , Fig. 9B or Fig. 10B The reference pattern is recorded in advance in the memory of the optical encoder 500.

[0071] Step S123: During assembly and installation, the first photodiode APD+ and the second photodiode APD- are used to generate a current output signal through the transimpedance amplifier 57. The processing circuit 59 obtains the current pattern in the same manner as the reference pattern (i.e., the voltage signal is generated through the transimpedance amplifier and normalized). As mentioned above, when there is a positional offset between the coding medium 53 and the photodetector 55, the current pattern will be different from the pre-stored reference pattern.

[0072] Step S125: The user changes, manually or automatically, the relative positions of the encoding medium 53 and the light detector 55 so that the current pattern is substantially the same as the reference pattern, thereby completing the position calibration.

[0073] For example, the optical encoder 500 may be connected to a display, which is used to display the current pattern obtained in step S123 and the pre-stored reference pattern in real time for the user to perform a calibration procedure.

[0074] In another embodiment, the reference pattern is not stored or recorded in the memory of the optical encoder 500, but is a known theoretical reference pattern when the encoding medium 53 and the light detector 55 are arranged at a standard relative position, such as Figure 6 , Figure 8B , Fig. 9B and Fig. 10B The current pattern obtained from the output signals of the first photodiode APD+ and the second photodiode APD- is displayed on the screen of an oscilloscope, for example. Thus, the calibration procedure is to complete the position calibration method by changing the relative position of the coding medium 53 and the photodetector 55 so that the current pattern is as close to the theoretical pattern as possible.

[0075] Please refer to Fig.13 As shown, it is a flow chart of a position correction method for an optical encoder 500 according to another embodiment of the present invention, comprising the following steps: predetermining a plurality of correction patterns based on reference output signals of a first photodiode and a second photodiode, wherein one of the plurality of correction patterns is a reference pattern in which the coding medium and the light detector are located at predetermined relative positions, and the other plurality of correction patterns are sub-reference patterns in which the coding medium and the light detector are located at different relative positions (step S131); determining a current pattern based on current output signals of the first photodiode and the second photodiode (step S133); comparing the current pattern with the plurality of sub-reference patterns to determine an offset direction of the coding medium and the light detector (step S135); and after moving at least one of the coding medium and the light detector in a direction opposite to the offset direction, repeating steps S133 to S135 until the current pattern is equal to the reference pattern (step S137).

[0076] Step S131: This step is similar to Fig.12 In step S131, in addition to recording the reference pattern of the coding medium 53 and the light detector 55 at the predetermined relative position, for example Figure 6 , Figure 8B , Fig. 9B or Fig. 10BAs shown, a secondary reference pattern in which the coding medium 53 and the light detector 55 are located at different relative positions (non-standard operating positions) is also recorded, for example Figure 7A-7H In the present invention, the reference pattern and the secondary reference pattern are collectively referred to as calibration patterns.

[0077] Step S133: This step is similar to Fig.12 The process is the same as step S123, so it will not be described again here.

[0078] Step S135: When the encoding medium 53 and the light detector 55 are not located at the correct standard position (i.e., the predetermined relative position), the current pattern will be substantially the same as one of the multiple secondary reference patterns but will not be the same as the reference pattern. Therefore, the user can determine the offset direction of the encoding medium 53 and the light detector 55 based on the comparison result. For example, the optical encoder 500 can be connected to a display, which is used to display the current pattern obtained in step S133 and the multiple pre-stored calibration patterns in real time for the user to compare.

[0079] It is understood that there is no specific limit to the number of the pre-stored multiple calibration patterns, which can be determined according to the memory space and the calibration accuracy. In addition, the multiple calibration patterns can also be selected to be stored in the memory or cloud of the external device of the optical encoder 500, wherein the external device has a display for real-time display of the current pattern and multiple calibration patterns for the user to perform the calibration procedure.

[0080] Step S137: The user moves at least one of the encoding medium 53 and the light detector 55 in the opposite direction of the offset direction, and repeats steps S133 to S135 until the current pattern is substantially equal to the reference pattern.

[0081] For example, if the user determines in step S135 that the current pattern is substantially the same as Fig.7D , it can be determined that the current position of the light detector 55 has a position offset of -a in the tangential direction and the axial direction and a position offset of -b in the height direction from the predetermined position. At this time, the user first moves the light detector 55 in the height direction by a distance of +b so that the current pattern is substantially the same as Figure 7C Next, the user moves the light detector 55 in the tangential direction and the axial direction in sequence by a distance +a until the current pattern is substantially the same as Figure 6 , the position calibration is completed. In addition, the user can also perform position calibration by moving the encoding medium 53. It can be understood that during the calibration process, the processing circuit 59 can continuously generate the current pattern at a predetermined frequency for comparison and calibration.

[0082] In other embodiments, the position correction step may also be performed automatically by pre-written control software and / or firmware code in conjunction with a motor to correct the relative position of the encoding medium 53 and the light detector 55, rather than being limited to manual correction by the user.

[0083] In another embodiment, the plurality of calibration patterns are not stored or recorded in the memory of the optical encoder 500 in advance, but are theoretical calibration patterns when the encoding medium 53 and the light detector 55 are arranged at different relative positions, such as 7A to 7H The current pattern obtained from the output signals of the first photodiode APD+ and the second photodiode APD- is displayed on the screen of an oscilloscope, for example. Thus, the calibration procedure determines the offset direction by changing the relative position of the coding medium 53 and the photodetector 55 so that the current pattern has the highest similarity with the theoretical pattern associated with the different relative positions. After the offset direction is obtained, the position calibration method can be completed by executing step S137.

[0084] It should be noted that, although the above embodiment is described by taking a set of correction diodes as an example, the present invention is not limited thereto. In other embodiments, the optical encoder 500 may include multiple sets of correction diodes, such as the above Figure 5B , Fig. 8A , Fig. 9A , Fig. 10A and Fig.11 It is sufficient to store the correction patterns related to each group of correction diodes in memory.

[0085] In addition, the shape and size of the correction diode are not limited to those provided in the present invention. As long as the reference patterns (similar to Figure 6 , Figure 8B , Fig. 9B and Fig. 10B ), and during the calibration process, the reference pattern can be reproduced by changing the relative positions of the components, thereby achieving the position calibration of the present invention.

[0086] In summary, the assembly and assembly of conventional optical encoders will cause positional deviation and reduce the position determination accuracy, and high-precision assembly and assembly control require high costs. Therefore, the present invention further provides an optical encoder capable of correcting the relative position of components (for example, referring to Figure 5B ) and position correction method thereof (for example, referring to Fig.12 and Fig.13 ), it is only necessary to set up at least one set of correction diodes and record in advance the reference pattern related to the output signal of the set of correction diodes in the standard operating position, so that the purpose of position correction can be achieved at a low cost.

[0087] Although the present invention has been disclosed through the above examples, they are not intended to limit the present invention. Any person skilled in the art with ordinary knowledge in the art to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims.

Claims

1. A method for position correction of an optical encoder, The optical encoder contains: A light detector for receiving modulated light from a coded medium, comprising: a detection diode array, the detection diode array being arranged relative to the encoding medium; and a first photodiode and a second photodiode, the first photodiode and the second photodiode are respectively located on both sides of the detection diode array, and each of the first photodiode and the second photodiode has a trapezoidal detection surface, The position correction method comprises: determining a reference pattern in advance according to reference output signals of the first photodiode and the second photodiode; Determine a current pattern according to current output signals of the first photodiode and the second photodiode; and The relative positions of the coding medium and the light detector are adjusted so that the current pattern is the same as the reference pattern. 2 . The position correction method of an optical encoder according to claim 1 , wherein the detection diode array and the first photodiode and the second photodiode are located on the same track.

3. The method for position correction of an optical encoder according to claim 1, wherein The coded medium has a code for modulating incident light, The code on the coding medium has a reflective portion and a non-reflective portion, and The width of the detection surface of each photodiode of the detection diode array is equal to half of the width of the reflection part and the non-reflection part. 4 . The position correction method of an optical encoder according to claim 1 , wherein a first distance from the first photodiode to a first side of the detection diode array is equal to a second distance from the second photodiode to a second side of the detection diode array. 5 . The position correction method of an optical encoder according to claim 1 , wherein a first distance from the first photodiode to a first side of the detection diode array is not equal to a second distance from the second photodiode to a second side of the detection diode array.

6. The method for position correction of an optical encoder according to claim 1, wherein The coded medium has a code for modulating incident light, The code on the coding medium has a reflective portion and a non-reflective portion, and The first photodiode is opposite to one of the reflective portions and the second photodiode is opposite to one of the non-reflective portions.

7. The position correction method of an optical encoder according to claim 1, wherein The coded medium has a code for modulating incident light, The code on the coding medium has a reflective portion and a non-reflective portion, and The widths of the first photodiode and the second photodiode are equal to the widths of the reflective portion and the non-reflective portion.

8. The method for position correction of an optical encoder according to claim 1, wherein The coded medium has a code for modulating incident light, The code on the coding medium has a reflective portion and a non-reflective portion, and The widths of the first photodiode and the second photodiode are equal to half of the widths of the reflective portion and the non-reflective portion. 9 . The position correction method of an optical encoder according to claim 1 , wherein the long sides of the two parallel sides of the trapezoidal detection surfaces of the first photodiode and the second photodiode face the detection diode array.

10. The position correction method of an optical encoder according to claim 1, wherein The long sides of the two parallel sides of the trapezoidal detection surface of the first photodiode face the detection diode array, and The short sides of the two parallel sides of the trapezoidal detection surface of the second photodiode face the detection diode array. 11 . The position correction method of an optical encoder according to claim 1 , wherein inclined sides of the trapezoidal detection surfaces of the first photodiode and the second photodiode face the same direction. 12 . The position correction method of an optical encoder according to claim 1 , wherein the inclined sides of the trapezoidal detection surfaces of the first photodiode and the second photodiode face in different directions.

13. A position correction method for an optical encoder according to claim 1, wherein the optical encoder further comprises a memory for pre-recording the reference pattern related to the reference output signals of the first photodiode and the second photodiode when the encoding medium and the light detector are located at a predetermined relative position. 14 . The position calibration method of an optical encoder according to claim 1 , wherein the reference output signal and the current output signal are normalized voltage signals. 15 . The position calibration method of an optical encoder according to claim 1 , wherein the relative position comprises a tangential direction position, an axial direction position, and a height direction position.

16. A method for position correction of an optical encoder, The optical encoder contains: A light detector for receiving modulated light from a coded medium, comprising: a detection diode array, the detection diode array being arranged relative to the encoding medium; and a first photodiode and a second photodiode, the first photodiode and the second photodiode are respectively located on both sides of the detection diode array, and each of the first photodiode and the second photodiode has a trapezoidal detection surface, The position correction method includes: Determining a plurality of calibration patterns in advance according to reference output signals of the first photodiode and the second photodiode, wherein one of the plurality of calibration patterns is a reference pattern in which the coding medium and the photodetector are located at a predetermined relative position, and the other plurality of calibration patterns are secondary reference patterns in which the coding medium and the photodetector are located at different relative positions; Step A: determining a current pattern according to current output signals of the first photodiode and the second photodiode; Step B: comparing the current pattern with the plurality of sub-reference patterns to determine the offset direction of the coding medium and the light detector; and Step C: moving at least one of the coding medium and the light detector in a direction opposite to the offset direction, and repeatedly performing steps A to C until the current pattern is equal to the reference pattern. 17 . The position correction method according to claim 16 , wherein the offset direction comprises a tangential direction, an axial direction and a height direction. 18 . The position calibration method according to claim 16 , wherein the reference output signal and the current output signal are normalized voltage signals.

19. The position correction method according to claim 16, wherein the optical encoder further comprises a memory for pre-recording the plurality of correction patterns associated with the reference output signals of the first photodiode and the second photodiode when the encoding medium and the light detector are located at different relative positions.

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