TW201928303A - Optical encoder - Google Patents

Abstract

An optical encoder comprises a light source module, a photodetector, a code disc, a first lens element assembly and a second lens element assembly. The light source module emits light rays. The photodetector is for detecting light rays. The code disc is disposed between the light source module and the photodetector. The first lens element assembly is disposed between the light source module and the code disc. There is a first distance between the first lens element assembly and the light source module, and there is a second distance between the first lens element assembly and the code disc. The second lens element assembly is disposed between the code disc and the photodetector. There is a third distance between the second lens element assembly and the code disc, and there is a fourth distance between the second lens element assembly and the photodetector. The relationship among the first distance, the second distance, the third distance and the fourth distance meets the definition of symmetric double projection optical system. Therefore, the first lens element assembly converges the light rays onto the code disc, and the second lens element assembly converges the light rays onto the photodetector.

Description

Optical encoder

The present invention relates to an optical encoder, and more particularly to an optical encoder in which the optical lens assembly conforms to the principle of symmetrical optical projection.

The encoder is used as a sensing module for servo motor positioning, and is widely used in machine tools, robots, and semiconductor devices. Among them, the accuracy of the encoder directly affects the positioning performance of the mechanical equipment. At present, the global industry's overall automation drive, the demand for servo motors is increasing.

An encoder is a sensor, software, or algorithm that converts information from a specific format to another specific format. The purpose of the conversion may be due to standardization, speed, confidentiality, security, or compression of data. Among them, the rotary encoder is an electromechanical device that converts the rotational position or the rotational amount into an analog or digital signal, and is mainly classified into an optical encoder and a mechanical encoder according to the configuration. In the optical encoder, there is also a disc that rotates synchronously with the spindle. The disc is made of glass or plastic, and has a plurality of concentric circles of transparent and opaque areas. There are light source and photosensor arrays on both sides of the disc. The read data can indicate the position of the disc and transfer the read data to the microprocessor for conversion to the position of the shaft.

The conventional optical encoder has a positioning width of only 10 micrometers per bit when the positioning accuracy is 24-bit, which has reached the limit of the resolution of the conventional optical combination, and causes a diffraction interference problem. In addition, due to the linear advancement of the beam, the sensing elements of the photodetector also need to be closely arranged at a width of 10 microns, so that there is extremely high difficulty in the fabrication or assembly alignment of the detector array.

In addition, the conventional optical encoder uses a laser light source (Laser Diode, LD) for increasing energy, which causes an increase in the production cost of the encoder and a short service life. Moreover, when the optical encoder uses a laser as a light source, it is necessary to fabricate an optical encoder disk with a high-precision photomask process to enable the photodetector to receive the coded signal by using a diffraction phenomenon. This causes the encoder to have a higher production cost, which in turn leads to a problem of low mass productivity.

An optical encoder according to an embodiment of the invention includes a light source module, a light detector, a code disk, a first optical lens group and a second optical lens group. The light source module is used to emit a light beam. A photodetector is used to receive the light beam. The code disc is between the light source module and the photodetector. The first optical lens group is located between the light source module and the code disk. The first optical lens group maintains a first distance from the light source module, and the first optical lens group maintains a second distance from the code disk. The second optical lens group is located between the encoder disc and the photodetector. The second optical lens group maintains a third distance from the encoder disc, and the second optical lens group maintains a fourth distance from the photodetector. Wherein, the first distance, the second distance, the third distance, and the fourth distance conform to the definition of the symmetric optical projection principle, so that the first optical lens group focuses the light beam from the light source module to the code disk, and makes the second optical The lens group focuses the beam that penetrates the encoder disk to the photodetector.

An optical encoder according to another embodiment of the present invention includes a light source module, an encoder disk, a photodetector, an optical lens group, a reflective polarizing element, and a polarization beam splitter. The light source module is used to emit a light beam. The encoder disc is located on the beam path. The illuminator is used to receive the light beam passing through the encoder disk. The optical lens group is located between the light source module and the code disk. The optical lens assembly maintains a first distance from the light source module, and the optical lens assembly maintains a second distance from the encoder disk. The reflective polarizing element is located on a side of the encoder disk remote from the optical lens group for reflecting the light beam passing through the encoder disk. The polarization beam splitter is located between the light source module and the optical lens group. The polarization beam splitter maintains a fifth distance from the optical lens assembly, and the polarization beam splitter maintains a sixth distance from the photodetector. Wherein, the sum of the fifth distance and the sixth distance length is equal to the first distance, and the first distance, the second distance, the fifth distance and the sixth distance conform to the definition of the symmetric optical projection principle, so that the optical lens group will come from The light beam of the light source module and passing through the polarization beam splitter is focused to the encoder disc, and the light beam reflected by the reflective polarizing element is focused to the polarization beam splitter, and then the beam is reflected by the polarization beam splitter to the light detector.

According to the optical encoder disclosed in the above embodiment, the optical lens group concentrates the light beam, and the light beam is focused on the encoder disk to pass the grating having a width of only 6 to 10 micrometers, and the light diverged by the encoder disk is focused to The illuminator, through the principle of symmetrical optical projection, has a lens-designed specific image-receiving position so that the encoded beam can be illuminated to the illuminator with a large width. In this way, the sensing unit on the photodetector can be arranged in a looser arrangement, so that the alignment accuracy requirement with the encoder disc is reduced. Thereby, the resolution obstacle of the high-precision position coding of the traditional encoder can be broken, and the alignment precision can also be reduced. In addition, by focusing the light beam on the encoder disc, the light beam irradiated on the photodetector has a larger energy, thereby making the encoded signal irradiated to the photodetector clearer and thus better. The signal noise ratio.

The above description of the present invention and the following description of the embodiments are intended to illustrate and explain the principles of the invention, and to provide a further explanation of the scope of the invention.

The detailed features and advantages of the embodiments of the present invention are set forth in the Detailed Description of the Detailed Description. The objects and advantages of the present invention can be readily understood by those of ordinary skill in the art in the <RTIgt; The following examples are intended to describe the present invention in further detail, but are not intended to limit the scope of the invention.

1 and FIG. 2, FIG. 1 is a side elevational view of an optical encoder according to a first embodiment of the present invention, and FIG. 2 is a partial front elevational view of the encoder disk of FIG. 1.

The optical encoder 1 of the present embodiment includes a light source module 10, a photodetector 20, a sensing circuit 30, an encoder disk 40, a first optical lens group 50, and a second optical lens group 60.

In this embodiment, the light source module 10 is a micro LED array for emitting a light beam L that is an elongated light field. The advantage of the miniature light-emitting diode used in the light source module 10 of the present embodiment is that it can be matched with an optical encoder disk manufactured by a photomask process with a line width of 2 micrometers or more, compared with a laser diode (LD) and its laser diode (LD). A high-precision photomask (with an accuracy of about 0.25 μm), a miniature light-emitting diode, and a photomask used to fabricate the optical encoder disc with it are less expensive to produce. In addition, the life of the miniature light-emitting diode is generally longer than that of the laser diode. That is to say, compared with the laser diode, the miniature light-emitting diode has the characteristics of high productivity and high durability. However, the feature of using a miniature light-emitting diode as a light source is not intended to limit the invention. In other embodiments, the light source module can also adopt a light emitting diode (LED) according to actual needs.

The light detector 20 is disposed relative to the light source module 10 for receiving the light beam L emitted by the light source module 10. In the present embodiment, the photodetector 20 is composed of a plurality of sensing elements 21, and the sensing element 21 is a photodiode (PD), but the invention is not limited thereto. In other embodiments, the photodetector may be a sensing array module or a plurality of sensing array modules; in addition, the sensing component 21 may also be an avalanche photodiode (APD).

The sensing circuit 30 is connected to the photodetector 20 for parsing the signal transmitted by the photodetector 20.

The code disc 40 is interposed between the light source module 10 and the photodetector 20. The center of the encoder disc 40 can be connected to a rotating shaft (not shown) of a motor (not shown), thereby driving the encoder disc 40 through a motor (not shown). Rotate.

The first optical lens group 50 is located between the light source module 10 and the encoder disk 40. The first optical lens group 50 includes a first lens 51 and a second lens 53, and the second lens 53 is closer to the encoder disk 40 than the first lens 51. The first optical lens group 50 maintains a first distance D1 with the light source module 10, and the first optical lens group 50 and the encoder disk 40 maintain a second distance D2.

The second optical lens group 60 is located between the encoder disk 40 and the photodetector 20. The second optical lens group 60 includes a first lens 61 and a second lens 63, and the second lens 63 is closer to the encoder disk 40 than the first lens 61. The second optical lens group 60 maintains a third distance D3 with the encoder disk 40, and the second optical lens group 60 maintains a fourth distance D4 with the photodetector 20.

Please refer to the following Table 1 for the first and second optical lens groups 50, 60 of this embodiment. In one example, the optical parameter list of each lens.

In the embodiment, the first distance D1 is equal to the fourth distance D4, the second distance D2 is equal to the third distance D3, and the first distance D1 is different from the second distance D2. As such, the first distance D1, the second distance D2, the third distance D3, and the fourth distance D4 conform to the definition of the principle of symmetric optical projection. By the function of concentrating the first optical lens group 50 and the second optical lens group 60, the first optical lens group 50 focuses the light beam L from the light source module 10 to a grating having only a width of, for example, 10 to 40 micrometers. The encoder disk 40 is mounted on the optical disc 20 and the second optical lens group 60 is caused to diverge the light beam L diverging through the encoder disk 40 to the photodetector 20 at a pitch greater than 10 to 40 micrometers. Thereby, the sensing elements 21 on the photodetector 20 can be arranged in a looser arrangement, so that the alignment accuracy requirement with the encoder disk 40 is reduced. In addition, by focusing the light beam L on the encoder disk 40, the light beam L irradiated on the photodetector 20 of the present embodiment has a larger energy than that of the parallel light projection. The encoded signal illuminated by the photodetector 20 is made clearer, thereby providing a better signal to noise ratio.

The distance between the first optical lens group 50 and the second optical lens group 60 and the light source module 10, the code disk 40, and the photodetector 20 (that is, the first distance D1, the second distance D2, the third distance D3, and the fourth The relationship of distance D4) is not intended to limit the invention. In other embodiments, the first distance, the second distance, the third distance, and the fourth distance may all be equal, in accordance with the definition of the symmetric optical projection principle, or in other embodiments, the first distance is equal to the first The second distance is equal to the fourth distance, and the first distance may be different from the third distance.

In the embodiment, the code disk 40 includes an absolute code pattern and a fine split code pattern. In detail, referring to FIG. 2, the code disc 40 includes a plurality of transparent regions 41 and a plurality of opaque regions 43. The shapes of the transparent regions 41 and the opaque regions 43 are substantially quadrangular and interlaced with each other. Arrange to form a coding pattern. The substantially quadrangular shape is a line in which the light-transmissive region 41 and the opaque region 43 are curved in the tangential direction, and a straight line in the radial direction forms a quadrangular region.

Please refer to FIG. 3 , which is a partially enlarged schematic view of the absolute code pattern on the photodetector and the code disc of FIG. 1 . The transparent transmissive region 41 and the opaque region 43 of the absolute coding pattern are all rectangular in shape, and the width W may be, for example, 10 micrometers. In this embodiment, the absolute coding pattern has 14 coding patterns along the optical field direction of the elongated beam L, and cooperates with the 14 sensing elements 21 on the photodetector 20 to pass through the transparent region 41 and is impermeable. The specific coding arrangement of the optical zone 43 provides an optical positioning accuracy of 14 bits. The absolute coding pattern may be, for example, a Binary-Coded Decimal (BCD) code or a Gray code, but is not limited thereto. In the present embodiment, the feature that the number of coding patterns in the direction of the light beam L is 14 is not intended to limit the present invention. In other embodiments, the number of coded patterns in the direction of the beam can be increased or decreased as needed.

Please refer to FIG. 4A to FIG. 4C , which are partial enlarged and actuated diagrams of the fine division coded pattern on the photodetector and the code disc of FIG. 1 . The light transmissive region 41 and the opaque region 43 of the finely divided coding pattern are all in the shape of a parallelogram and staggered with each other, and the code width W thereof can be, for example, 10 micrometers. When the code disk 40 is rotated, since the shape of the light transmitting region 41 is a parallelogram, the light beam L irradiated on the code disk 40 can be irradiated to the rear of the code disk 40 only at a part of the light beam L at the same time. The plurality of sensing elements 21 of the photodetector 20 (see the sensing element 21 labeled 1 in FIGS. 4A-4C), while the other portion of the light beam L is blocked by the opaque region 43. As shown in FIG. 4A, on the schematic view of a partially enlarged area of the encoder disk 40, only the uppermost sensing element 21 is illuminated by the light beam L, and the remaining sensing elements 21 (such as the sensing element 21 labeled 0 in FIG. 4A) Then, the beam L is not sensed because the corresponding beam L position is blocked by the opaque region 43. As the encoder disk 40 rotates, as shown in FIG. 4B at a certain time, in this region, the entire light beam L is not blocked by the opaque region 43, so that all of the rear sensing elements 21 are subjected to the light beam L. Irradiation. Then, as the code disk 40 continues to rotate and at another time as shown in FIG. 4C, the light beam L is blocked by the opaque region 43 from above in the region, so that the uppermost sensing element 21 (as shown in FIG. 4C) The sensing element 21) labeled 0 is not illuminated by the beam. As such, the plurality of sensing elements 21 on the photodetector 20 may have a portion of the sensing element 21 sensing the light beam L at the same time, while the portion of the sensing element 21 does not sense the light beam L. Thereby, different numbers of sensing elements 21 sense the light beam L as the encoder disk 40 moves, and different positions can be resolved to achieve better resolution accuracy. In addition, the fine division type coding can also analyze the energy difference of the light beam L induced by the adjacent two sensing elements 21, thereby analyzing the positional accuracy of the multiple, and also reducing the number of uses of the sensing element 21.

In detail, in the fine division coding portion, when the sensing element 21 of the photodetector 20 can sense the energy difference of the light beam L and the number is 1024, a 10-bit signal resolution can be provided, and In the absolute coding portion, when the optical source module 10 is originally provided with an optical positioning resolution of, for example, 14 bits, the optical encoder 1 can achieve a resolution of 24 bits. In the present embodiment, the positional precision of the multiple can be resolved by analyzing the energy difference of the light beam L induced by the adjacent two sensing elements 21 through the fine division code pattern on the code disk of FIGS. 4A to 4C. For example, when the sensing element 21 can sense and analyze the illumination area and the corresponding amount of light energy, for example, the light energy that can be resolved is 100% or 50%, etc., the photodetector 20 has the same number. Under the sensing element 21, a higher multiple of positional accuracy can be resolved. In this way, the number of sensing elements 21 of the photodetector 20 can be reduced from 1024 to 512, or even 256, and the 10-bit signal resolution can be provided.

In this embodiment, the first lens 51 and the first lens 61 of the first and second optical lens groups 50 and 60 are both convex lenses, and the second lens 53 and the second lens 63 are both concave lenses, but the present invention does not This is limited to this. In other embodiments, the first lens and the second lens may be respectively designed as a concave lens or a convex lens according to actual needs. In addition, in the present embodiment, the feature that the number of lenses included in each of the first optical lens group 50 and the second optical lens group 60 is two is not intended to limit the present invention. In other embodiments, the two optical lens groups of the optical encoder may include one or more lenses according to actual needs.

For example, please refer to FIG. 5, which is a side view of an optical encoder according to a second embodiment of the present invention. This embodiment is similar to the first embodiment in that the first optical lens group 50a and the second optical lens group 60a of the optical encoder 1a of the present embodiment are the first lens 50a and the first lens 60a, respectively. In this embodiment, the first optical lens group 50a and the light source module 10a maintain a first distance D1a, the first optical lens group 50a and the code disk 40a maintain a second distance D2a, and the second optical lens group 60a and the code disk 40a maintains a third distance D3a, and the second optical lens group 60a maintains a fourth distance D4a with the photodetector 20a. The first distance D1a is equal to the fourth distance D4a, the second distance D2a is equal to the third distance D3a, and the first distance D1a is different from the second distance D2a. As such, the first distance D1a, the second distance D2a, the third distance D3a, and the fourth distance D4a of the present embodiment conform to the definition of the symmetric optical projection principle.

In the present embodiment, the first lens 50a and the first lens 60a of the first and second optical lens groups 50a and 60a are convex lenses, but the invention is not limited thereto.

Referring to Table 2 below, the first and second optical lens groups 50a, 60a of the present embodiment are an optical parameter list of each lens in an example.

Further, referring to Fig. 6, there is shown a side view of an optical encoder according to a third embodiment of the present invention. This embodiment is similar to the first embodiment in that the first optical lens group 50b of the optical encoder 1b of the present embodiment includes a first lens 55b, a second lens 57b, and a third lens 59b sequentially from the light source module 10b. The encoder discs 40b are arranged in the direction, and the second optical lens group 60b includes the first lens 65b, the second lens 67b, and the third lens 69b sequentially aligned from the photodetector 20b toward the encoder disc 40b. In this embodiment, the first optical lens group 50b and the light source module 10b maintain a first distance D1b, the first optical lens group 50b and the code disk 40b maintain a second distance D2b, and the second optical lens group 60b and the code disk 40b remain. The third distance D3b, and the second optical lens group 60b and the photodetector 20b maintain a fourth distance D4b. The first distance D1b is equal to the fourth distance D4b, the second distance D2b is equal to the third distance D3b, and the first distance D1b is different from the second distance D2b. As such, the first distance D1b, the second distance D2b, the third distance D3b, and the fourth distance D4b of the present embodiment conform to the definition of the symmetric optical projection principle.

Referring to Table 3 below, the first and second optical lens groups 50b, 60b of the present embodiment are an optical parameter list of each lens in an example.

In this embodiment, the first lens, the second lens, and the third lens of the optical lens group are respectively a convex lens, a concave lens, and a convex lens, but the invention is not limited thereto. In other embodiments, the first lens, the second lens, and the third lens may be respectively designed as a concave lens or a convex lens according to actual needs.

Each of the above embodiments exemplifies an optical lens group including different lens numbers. Wherein, when the number of lenses of each optical lens group is one piece (as described in the second embodiment), the grating width (i.e., the width of the light transmitting region) on the encoder disk is required to be 8 μm. When the number of lenses of each optical lens group is two (as described in the first embodiment), the grating width on the encoder disk is required to be 6 micrometers. More preferably, when the number of lenses of each optical lens group is three (as described in the third embodiment), the grating width requirement on the encoder disk may be less than 6 micrometers. Thereby, the light intensity received by the photodetector can be greatly improved to ensure that the encoding precision of the encoder meets the requirements.

Please refer to FIG. 7, which is a side view of an optical encoder according to a fourth embodiment of the present invention.

The optical encoder 1c of the present embodiment includes a light source module 10c, an encoder disk 40c, a photodetector 20c, a sensing circuit 30c, an optical lens group 70c, a reflective polarizing element 90c, and a polarized beam splitter (PBS) 80c. .

The light source module 10c is configured to emit a light beam Lc that is an elongated light field. The code disk 40c is located on the path of the light beam Lc. The photodetector 20c is for receiving the light beam Lc passing through the encoder disk 40c. The sensing circuit 30c is connected to the photodetector 20c for parsing the signal transmitted from the photodetector 20c.

The optical lens group 70c is located between the light source module 10c and the code disk 40c. The optical lens group 70c includes a first lens 71c and a second lens 73c, and the second lens 73c is closer to the encoder disk 40c than the first lens 71c. The optical lens group 70c maintains a first distance D1c with the light source module 10c, and the optical lens group 70c maintains a second distance D2c with the encoder disk 40c.

The reflective polarizing element 90c is located on the side of the encoder disk 40c remote from the optical lens group 70c for reflecting the light beam Lc passing through the encoder disk 40c. In this embodiment, the reflective polarizing element 90c can be, for example, a reflective single crystal germanium liquid crystal (LCOS) element, but is not limited thereto.

The polarization beam splitter 80c is located between the light source module 10c and the optical lens group 70c. In this embodiment, the photodetector 20c is located between the light source module 10c and the optical lens group 70c, and is located on one side of the polarization beam splitter 80c, but is not limited thereto. The polarization beam splitter 80c maintains a fifth distance D5c with the optical lens group 70c, and the polarization beam splitter 80c maintains a sixth distance D6c with the photodetector 20c. The sum of the lengths of the fifth distance D5c and the sixth distance D6c is equal to the first distance D1c.

In the embodiment, the first distance D1c is different from the second distance D2c. Thus, the first distance D1c, the second distance D2c, the fifth distance D5c, and the sixth distance D6c conform to the definition of the symmetric optical projection principle, so that the optical lens group 70c will come from the light source module 10c and penetrate the polarization beam splitter 80c. The light beam Lc is focused to the encoder disk 40c, and the light beam Lc reflected by the reflective polarizing element 90c is focused to the polarization beam splitter 80c, and then transmitted through the polarization beam splitter 80c to reflect the light beam Lc to the photodetector 20c.

The polarization beam splitter 80c of the present embodiment can pass light of a specific polarization direction and reflect light of a polarization direction perpendicular to the specific polarization direction. In addition, the reflective polarizing element 90c of the present embodiment can reflect light and change the polarization direction of the light, even if the polarization direction of the reflected light is, for example, perpendicular to the polarization direction of the incident light. Thereby, the polarization beam splitter 80c can pass the light beam Lc from the light source module 10c, and can reflect the light beam Lc which changes the polarization direction via the reflective polarizing element 90c.

The distance between the optical lens group 70c and the light source module 10c, the code disk 40c and the polarization beam splitter 80c, and the distance between the polarization beam splitter 80c and the light detector 20c (that is, the first distance D1c, the second distance D2c, and the fifth distance D5c) The relationship between the sixth distance D6c) and the sixth distance D6c) is not intended to limit the invention. In other embodiments, the sum of the fifth distance and the sixth distance length is equal to the first distance, the first distance being equal to the second distance, and conforming to the definition of the symmetric optical projection principle.

The code disk 40c of this embodiment is similar to the code disk 40 of the first embodiment, and has a plurality of light transmitting regions and a plurality of opaque regions to allow the light beam Lc that is irradiated onto the upper portion of the code disk 40c to pass through the light transmitting region. The reflective polarizing element 90c reflects the light beam Lc back to the optical lens group 70c through the reflective polarizing element 90c, and again focuses the diverged light beam Lc onto the polarizing beam splitter 80c by the optical lens group 70c, and then passes through the polarizing beam splitter 80c. The light beam Lc is reflected to the photodetector 20c. Thereby, the use of the lens can be reduced, thereby reducing the production cost; in addition, the partial volume of the optical path can be overlapped to reduce the overall volume of the optical encoder.

In the present embodiment, the first lens 71c and the second lens 73c of the optical lens group 70c are a convex lens and a concave lens, respectively, but the invention is not limited thereto. In other embodiments, the first lens and the second lens may be respectively designed as a concave lens or a convex lens according to actual needs.

Further, in the present embodiment, the feature that the number of lenses included in the optical lens group 70c is two is not intended to limit the present invention. In other embodiments, the two optical lens groups of the optical encoder may include one or more lenses according to actual needs.

According to the optical encoder of the above embodiment, by the function of the optical lens group concentrating the light beam, the light beam is focused on the encoder disk to pass through a light transmission region having a width of only 6 to 10 micrometers, and the light diverged by the encoder disk is focused to The illuminator, through the principle of symmetrical optical projection, has a lens-designed specific image-receiving position so that the encoded beam can be illuminated to the illuminator with a large width. In this way, the sensing elements on the photodetector can be arranged in a looser arrangement, so that the alignment accuracy requirements of the encoder disc are reduced. Thereby, the resolution obstacle of the high-precision position coding of the traditional encoder can be broken, and the alignment precision can also be reduced. In addition, by focusing the light beam on the encoder disc, the light beam irradiated on the photodetector has a larger energy, thereby making the encoded signal irradiated to the photodetector clearer and thus better. The signal noise ratio.

In addition, the micro-light-emitting diode used in the light source module can be matched with an optical encoder disk made by a photomask process with a line width of 2 micrometers or more, compared with a laser diode and a high-precision photomask to be matched with it, and a miniature light-emitting diode. The reticle of the body and the optical encoder disk used to make it is relatively low in production cost. In addition, the life of the miniature light-emitting diode is generally longer than that of the laser diode. Therefore, compared with the laser diode, the miniature light-emitting diode used in this case has the characteristics of high productivity and high durability.

Furthermore, through the fine-divided coding in which the coding pattern is a parallelogram, different numbers of sensing elements sense the light beam as the code disk moves, and different positions can be resolved to achieve better resolution. In addition, the fine division code can also be used to analyze the energy difference between the adjacent sensing elements and the beam, and the positional accuracy of the multiple can be simultaneously analyzed, and the number of sensing elements can be reduced.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The patent protection scope of the invention is subject to the definition of the scope of the patent application attached to the specification.

1, 1a, 1b, 1c‧‧‧ optical encoder

10, 10a, 10b, 10c‧‧‧ light source module

20, 20a, 20b, 20c‧‧‧ Detector

21‧‧‧Sensor components

30, 30c‧‧‧Sensor circuit

40, 40a, 40b, 40c‧‧‧ code disk

41‧‧‧Light transmission area

43, 43c‧‧‧ opaque area

45c‧‧‧Reflective zone

50, 50a, 50b‧‧‧ first optical lens group

51, 50a‧‧‧ first lens

53‧‧‧second lens

55b‧‧‧first lens

57b‧‧‧second lens

59b‧‧‧ third lens

60, 60a, 60b‧‧‧second optical lens group

61, 60a‧‧‧ first lens

63‧‧‧second lens

65b‧‧‧first lens

67b‧‧‧second lens

69b‧‧‧ third lens

70c‧‧‧ optical lens unit

71c‧‧‧first lens

73c‧‧‧second lens

80c‧‧‧Polarizing beam splitter

90c‧‧‧reflective polarizing element

L, Lc‧‧ beams

W‧‧‧Width

D1, D1a, D1b, D1c‧‧‧ first distance

D2, D2a, D2b, D2c‧‧‧ second distance

D3, D3a, D3b‧‧‧ third distance

D4, D4a, D4b‧‧‧ fourth distance

D5c‧‧‧ fifth distance

D6c‧‧‧ sixth distance

1 is a side elevational view of an optical encoder in accordance with a first embodiment of the present invention. 2 is a partial front elevational view of the encoder disk of FIG. 1. 3 is a partially enlarged schematic view showing an absolute coding pattern on the optical detector and the encoder disk of FIG. 1. 4A-4C are partial enlarged and actuated diagrams of the fine-divided coding pattern on the optical detector and the encoder disk of FIG. 1. Figure 5 is a side elevational view of an optical encoder in accordance with a second embodiment of the present invention. Figure 6 is a side elevational view of an optical encoder in accordance with a third embodiment of the present invention. Figure 7 is a side elevational view of an optical encoder in accordance with a fourth embodiment of the present invention.

Claims (21)

An optical encoder comprising: a light source module for emitting a light beam; a light detector for receiving the light beam; an encoder disk interposed between the light source module and the light detector; An optical lens group is disposed between the light source module and the code disk, the first optical lens group maintains a first distance from the light source module, and the first optical lens group maintains a second distance from the code disk; a second optical lens group is disposed between the code disc and the photodetector, the second optical lens group maintains a third distance from the encoder disc, and the second optical lens group and the photodetector maintain a fourth a distance, wherein the first distance, the second distance, the third distance, and the fourth distance conform to a definition of a symmetric optical projection principle, such that the first optical lens group focuses the light beam from the light source module And to the encoder disc, and causing the second optical lens group to focus the light beam that penetrates the encoder disc to the photodetector. The optical encoder of claim 1, wherein the first distance is equal to the fourth distance, the second distance is equal to the third distance, and the first distance is different from the second distance. The optical encoder of claim 1, wherein the first distance, the second distance, the third distance, and the fourth distance are all equal. The optical encoder of claim 1, wherein the first distance is equal to the second distance, the third distance is equal to the fourth distance, and the first distance is different from the third distance. The optical encoder of any one of claims 2 to 4, wherein the first optical lens group and the second optical lens group each comprise a first lens. The optical encoder of claim 5, wherein the first optical lens group and the second optical lens group each further comprise a second lens, the second lens of the first optical lens group being more The first lens of an optical lens group is adjacent to the code disk, and the second lens of the second optical lens group is closer to the code disk than the first lens of the second optical lens group. The optical encoder of claim 6, wherein the first optical lens group and the second optical lens group each further comprise a third lens, the third lens of the first optical lens group being more The second lens of an optical lens group is adjacent to the encoder disk, and the third lens of the second optical lens group is closer to the encoder disk than the second lens of the second optical lens group. The optical encoder of claim 1, wherein the code disc comprises a plurality of light transmissive regions and a plurality of opaque regions, wherein the light transmissive regions and the opaque regions are substantially one shape quadrilateral. The optical encoder of claim 8, wherein the quadrilateral is a rectangle. The optical encoder of claim 8, wherein the light transmitting regions and the opaque regions are staggered with each other, and the quadrilateral is a parallelogram. The optical encoder of claim 8, wherein the light transmitting regions have a width of 6 to 10 μm. The optical encoder of claim 1, wherein the light source module is a light emitting diode (LED) or a micro LED array. The optical encoder of claim 1, wherein the optical detector comprises at least one sensing array module or a plurality of sensing elements. The optical encoder of claim 13, wherein the at least one sensing array module and the sensing elements are a photodiode (PD) or an avalanche type photodiode (Avalanche). Photodiode, APD). The optical encoder of claim 1, further comprising a sensing circuit, the sensing circuit connecting the optical detector to parse the signal transmitted by the optical detector. An optical encoder comprising: a light source module for emitting a light beam; an encoder disk located in the beam path; a photodetector for receiving the light beam passing through the encoder disk; an optical lens group located at Between the light source module and the code disk, the optical lens group maintains a first distance from the light source module, and the optical lens group maintains a second distance from the code disk; a reflective polarizing element is located at the code disk a side away from the optical lens group for reflecting the light beam passing through the encoder disk; and a polarization beam splitter between the light source module and the optical lens group, the polarization beam splitter and the optical lens group maintaining a a fifth distance, the polarization beam splitter maintains a sixth distance from the photodetector; wherein a sum of the fifth distance and the sixth distance length is equal to the first distance, and the first distance and the second distance The fifth distance and the sixth distance conform to the definition of the symmetric optical projection principle, so that the optical lens group focuses the light beam from the light source module and penetrates the polarization beam splitter to the code disk And focusing the light beam reflected by the reflective polarizing element to the polarization beam splitter, and transmitting the light beam to the photodetector through the polarization beam splitter. The optical encoder of claim 16, wherein the first distance is different from the second distance. The optical encoder of claim 16, wherein the first distance is equal to the second distance. The optical encoder of claim 17 or claim 18, wherein the optical lens group comprises a first lens and a second lens, and the second lens is closer to the encoder disk than the first lens. The optical encoder of claim 16, wherein the code disc comprises a plurality of light transmissive regions and a plurality of opaque regions, the light transmissive regions and the opaque regions being staggered and shaped It is essentially a parallelogram. The optical encoder of claim 16, wherein the reflective polarizing element is a reflective single crystal germanium liquid crystal element.