An encoder based on transmission and reflection scheme

Abstract

The invention provides an encoder based on a transmission and reflection scheme, comprising: a scale grating, an indicating grating, a photoelectric receiver, a light source and a reflection switch group; the scale grating is provided with a vernier code channel group for single-turn counting and a Gray code channel group for multi-turn counting, the vernier code channel group is located in the transmission area of ​​the scale grating, the Gray code channel group is located in the transmission area and the reflection area of ​​the scale grating, and the Gray code channel group includes at least two Gray code channels; the reflection area of ​​the invention is located at the installation position of the scale grating and the rotating shaft, the position is not used in the existing encoder, and the total number of code channels is increased by using the position, which can be used for miniaturization of the encoder; the invention improves the calibration margin of the encoder by increasing the number of Gray code channels, thereby improving the fault tolerance of the encoder; the invention applies the reflection switch to the multi-turn counting of the encoder to avoid the limitation of the tube voltage drop of the light source on the multi-turn counting.

Description

Technical Field

[0001] The present invention relates to the field of encoders, and in particular to an encoder based on transmission and reflection schemes. Background Art

[0002] Photoelectric encoder is a digital inspection device that integrates light, mechanics and electricity. It is a sensor that converts the mechanical and geometric displacement input to the shaft into pulses or digital quantities through a photoelectric conversion circuit. It is mainly used for speed or position detection. It has the advantages of high precision, fast response, stable and reliable performance, etc.

[0003] Existing photoelectric encoders do not have a solution that combines transmission and reflection. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an encoder based on transmission and reflection solutions.

[0005] To achieve the above object, the present invention adopts the following specific technical solutions:

[0006] An encoder based on a transmission and reflection scheme includes: a scale grating, an indicator grating, a photoelectric receiver, a light source and a reflection switch group; the scale grating is provided with a vernier code group for single-turn counting and a Gray code group for multi-turn counting;

[0007] The vernier code channel group includes an M code channel, an N code channel and an S code channel, each of which is marked with a plurality of light-transmitting areas regularly distributed along the code channel; the Gray code channel group includes at least two Gray code channels, each of which is a regularly distributed light and dark stripe; the indicator grating is provided with at least five code channels corresponding to the vernier code channel group and the Gray code channel group, each code channel of the indicator grating is marked with a plurality of light-transmitting areas regularly distributed along the code channel;

[0008] The vernier code channel group is located in the transmission area of ​​the scale grating, and the Gray code channel group is located in the transmission area and the reflection area of ​​the scale grating;

[0009] The reflection area is located at the installation position of the scale grating and the rotating shaft.

[0010] Preferably, the N code channel, the M code channel and the S code channel are arranged sequentially from outside to inside, and at least two Gray code channels are respectively placed between the M code channel and the N code channel, between the M code channel and the S code channel, outside the N code channel or inside the S code channel.

[0011] Preferably, it also includes an optical system for converting light emitted by the light source into parallel light, and the optical system is placed between the light source and the scale grating.

[0012] Preferably, the scale grating is mounted on the rotating shaft by a light absorbing adhesive.

[0013] Preferably, the installation position of the rotating shaft is subjected to an oxidation blackening treatment.

[0014] Preferably, a light absorbing plate is further included, and the light absorbing plate is located at the installation position of the rotating shaft.

[0015] The present invention can achieve the following technical effects:

[0016] (1) The reflection area is located at the installation position of the scale grating and the rotating shaft. This position has not been used in existing photoelectric encoders, and existing photoelectric encoders do not have a combination of transmission and reflection. By using this position, the total number of code channels is increased, which can be used to miniaturize the encoder;

[0017] (2) By increasing the number of Gray code channels, the calibration margin of the encoder is increased, thereby improving the fault tolerance of the encoder and ensuring that the encoder can work normally under different working conditions;

[0018] (3) The voltage drop of the transmitted light source tube is large, and multi-turn counting cannot be performed. The reflective switch is applied to the multi-turn counting of the encoder to avoid the limitation of the voltage drop of the transmitted light source tube on the multi-turn counting;

[0019] (4) Magnetic encoding is not used for multi-turn counting, which improves the encoder's anti-interference, static electricity, and magnetoelectric capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of an encoder based on a transmission and reflection scheme according to an embodiment of the present invention;

[0021] Figure 2 is a schematic structural diagram of a scale grating according to an embodiment of the present invention;

[0022] Figure 3 is a schematic structural diagram of a photoelectric receiver according to an embodiment of the present invention;

[0023] Figure 4 is a schematic structural diagram of a reflective switch according to an embodiment of the present invention.

[0024] The reference numerals include: scale grating 1, indicator grating 2, photoelectric receiver 3, light source 4, rotating shaft 6, M code channel 1-1, N code channel 1-2, S code channel 1-3, first Gray code channel 1-4, second Gray code channel 1-5, third Gray code channel 1-6, fourth Gray code channel 1-7, transmission area 1-8, reflection area 1-9, M code channel optical signal receiving window 3-1, N code channel optical signal receiving window 3-2, S code channel optical signal receiving window 3-3, first Gray code channel optical signal receiving window 3-4, second Gray code channel optical signal receiving window 3-5, first reflection switch 5-1, second reflection switch 5-2, first reflection switch light source 5-1-1, first reflection switch photoelectric conversion chip 5-1-2. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0026] like Figure 1 As shown, the encoder based on the transmission and reflection scheme provided by the embodiment of the present invention includes: a scale grating 1, an indicator grating 2, a photoelectric receiver 3, a light source 4 and a reflection switch group; the scale grating 1 is provided with a vernier code group for single-turn counting and a Gray code group for multi-turn counting;

[0027] The light emitted by the light source 4 is received by the photoelectric receiver 3 through the light-transmitting area of ​​the scale grating 1 and the light-transmitting area of ​​the indicator grating 2 in turn, and is converted into an electrical signal for output after amplification, shaping, filtering and other processing;

[0028] like Figure 3 As shown, the lower surface of the photoelectric receiver 3 is provided with a plurality of optical signal receiving windows, which correspond to the vernier code channel group and the Gray code channel group respectively, including the M code channel optical signal receiving window 3-1, the N code channel optical signal receiving window 3-2, the S code channel optical signal receiving window 3-3, the first Gray code channel optical signal receiving window 3-4, and the second Gray code channel optical signal receiving window 3-5.

[0029] like Figure 1 As shown, the reflection switch group of this embodiment includes a first reflection switch 5-1 and a second reflection switch 5-2. The light emitted by the first reflection switch 5-1 and the second reflection switch 5-2 is reflected by the reflective area of ​​the scale grating 1, and returns to the first reflection switch 5-1 and the second reflection switch 5-2 respectively, and is received by the first reflection switch 5-1 and the second reflection switch 5-2, and is converted into electrical signals for output. According to the electrical signals output by the photoelectric receiver 3 and the reflection switch group, the rotation angle of the rotating shaft 6 on which the encoder is installed is obtained; the tube voltage drop of the light source 4 is large, and multi-turn counting cannot be performed. The reflection switch is applied to the multi-turn counting of the encoder to avoid the limitation of the tube voltage drop of the light source 4 on the multi-turn counting.

[0030] The reflective switches included in the reflective switch group have the same structure, including a reflective switch light source and a photoelectric conversion chip, such as Figure 4 As shown, taking the first reflective switch 5-1 as an example, the first reflective switch 5-1 includes a first reflective switch light source 5-1-1 and a first reflective switch photoelectric conversion chip 5-1-2.

[0031] When the scale grating 1 rotates, the shielding conditions of the vernier code channel group and the Gray code channel group on the light source 4 change, cutting the incident light signal into signals of varying strengths, causing the intensity of the light received by the photoelectric receiver 3 to change, thereby changing the electrical signal output by the photoelectric receiver 3.

[0032] like Figure 2 As shown, the cursor code channel group includes M code channel 1-1, N code channel 1-2 and S code channel 1-3, and M code channel 1-1, N code channel 1-2 and S code channel 1-3 are all marked with multiple light-transmitting areas regularly distributed along the code channels, so that M code channel 1-1, N code channel 1-2 and S code channel 1-3 are all light and dark stripes, wherein the light-transmitting area position is a bright stripe, and the opaque position is a dark stripe; the Gray code channel group includes at least two Gray code channels. The Gray code channels are all regularly distributed light and dark stripes. In this embodiment, the Gray code channel group includes four Gray code channels, namely the first Gray code channel 1-4, The second Gray code channel 1-5, the third Gray code channel 1-6, and the fourth Gray code channel 1-7, the first Gray code channel 1-4 and the second Gray code channel 1-5 are located in the transmission area 1-8, and the third Gray code channel 1-6 and the fourth Gray code channel 1-7 are located in the reflection area 1-9; the indicator grating 2 is provided with at least five code channels corresponding to the vernier code channel group and the Gray code channel group, and each code channel of the indicator grating 2 is engraved with a plurality of light-transmitting areas regularly distributed along the code channel, so that each code channel of the indicator grating 2 is also a stripe of alternating light and dark, wherein the light-transmitting area position is a bright stripe, and the light-impermeable position is a dark stripe;

[0033] The vernier code channel group is located in the transmission area 1-8 of the scale grating 1, the Gray code channel group is located in the transmission area 1-8 and the reflection area 1-9 of the scale grating 1, and the number of reflection switches included in the reflection switch group is the same as the number of Gray code channels located in the reflection area 1-9; the surface light reflectivity of the code channels in the reflection area 1-9 is ≥50%, and in order to avoid stray light affecting the signal quality, the light transmittance of the reflection area 1-9 of the scale grating 1 is ≥90%; the reflection area 1-9 is located at the installation position of the scale grating 1 and the rotating shaft 6, which position has not been used in the existing encoder, and the total number of code channels is increased by using this position.

[0034] When the cursor operation is performed according to the M code channel 1-1, the N code channel 1-2 and the S code channel 1-3, and the encoder output is obtained together, the encoder is an absolute encoder. When the encoder output is obtained according to any one of the M code channel 1-1, the N code channel 1-2 and the S code channel 1-3, the encoder is an incremental encoder.

[0035] In one embodiment of the present invention, the N code channel 1-2, the M code channel 1-1 and the S code channel 1-3 are arranged sequentially from the outside to the inside, and at least two Gray code channels are placed between the M code channel 1-1 and the N code channel 1-2, between the M code channel 1-1 and the S code channel 1-3, on the outside of the N code channel 1-2 or on the inside of the S code channel 1-3; the position of the Gray code channel has no effect on the effect of the Gray code and can be set according to the actual situation of the ruler grating 1.

[0036] In one embodiment of the present invention, an optical system for converting light emitted by the light source 4 into parallel light is also included, and the optical system is placed between the light source 4 and the scale grating 1; by converting the light into parallel light and performing uniform light, the light intensity of the light irradiated to the scale grating 1 is made uniform.

[0037] In one embodiment of the present invention, the scale grating 1 is mounted on the rotating shaft 6 by a light-absorbing adhesive to improve the contrast between the reflective area and the non-reflective area of ​​the reflective area 1-9.

[0038] In one embodiment of the present invention, the installation position of the rotating shaft 6 is subjected to an oxidation blackening treatment to prevent the photoelectric conversion chip from being affected by the environment and the stray light reflected by the scale grating 1 .

[0039] In one embodiment of the present invention, a light absorbing plate is further included. The light absorbing plate is located at the installation position of the rotating shaft 6. The light absorbing plate is placed between the rotating shaft 6 and the scale grating 1 to absorb stray light and further improve the contrast between the reflective area and the non-reflective area of ​​the reflective area 1-9.

[0040] The advantages of the present invention are described in detail below:

[0041] The calibration value of the encoder is obtained by cursor calculation according to the phase deviation of S code channel 1-3 and N code channel 1-2 relative to M code channel 1-1. The larger the position phase deviation of S code channel 1-3 and N code channel 1-2 relative to M code channel 1-1, the larger the calibration value. Under the premise that the overall structure of the encoder remains unchanged, when the temperature changes, the material expands and contracts, that is, the relative position of the scale grating 1 and the photoelectric receiver 3 shifts, resulting in an increase in the calibration value of the encoder. When the calibration value is ≥ the calibration tolerance, the encoder alarm will fail to operate normally. Therefore, increasing the calibration margin of the encoder can improve the temperature adaptability of the encoder.

[0042] When the encoder counts a single circle, N code channel 1-2 and S code channel 1-3 need to be synchronized with M code channel 1-1, so synchronization bits need to be set. The more synchronization bits there are, the easier it is to synchronize. However, the encoder accuracy decreases as the number of synchronization bits increases. In the present invention, the number of synchronization bits c=4.

[0043] The required number of physical markings for M channel 1-1 is 2 a, that is, the number of physical bits output by the encoder is a bits, and the number of pulses of the M code channel 1-1 in each electrical cycle is 2 n+s , the number of pulses in N code channel 1-2 is 2 n+s -1, the number of pulses of S code channel 1-3 is 2 n+s -2 s According to the encoder principle, equation (1) can be obtained:

[0044] a=n+s+b (1)

[0045] Among them, n is the number of used bits of N code channels 1-2 in the output electrical signal, s is the number of used bits of S code channels 1-3 in the output electrical signal, and b is the number of Gray code channels contained in the Gray code channel group; since the used bits of N code channels 1-2 are the high bits of the encoder, in order to reduce the probability of encoder reading errors, n=s or n=s+1 is usually used.

[0046] The calculation formula of the encoder calibration margin is as follows:

[0047] K=±7(360° / 2 n+c ) (2)

[0048] Where K is the calibration margin of the encoder;

[0049] It can be seen from equations (1) and (2) that, when the number of markings of M code channel 1-1, N code channel 1-2 and S code channel 1-3 remains unchanged, increasing the number of Gray code channels can effectively improve the calibration margin of the encoder.

[0050] The present invention can be applied to the development of high-resolution and high-precision encoders. In one embodiment of the present invention, the number of markings of the M code channel 1-1 of the scale grating 1 is 2048P / r, that is, the number of bits of the electrical signal output by the encoder is a=11 bits.

[0051] Select n=s=4, and in each electrical cycle of scale grating 1, the number of pulses of M code channel 1-1 is 2 4+4 , the number of pulses in N code channel 1-2 is 2 4+4 -1, the pulse numbers of S channels 1-3 are 2 4+4 -2 4 , according to the calculation, the number of Gray code channels b=3.

[0052] The encoder calibration margin K is calculated to be ±9.84°, which is twice the calibration margin of the encoder of the current transmission solution.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0054] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0055] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An encoder based on a transmission and reflection scheme, characterized in that: include: A scale grating, an indicator grating, a photoelectric receiver, a light source and a reflection switch group; the scale grating is provided with a vernier code channel group for single-turn counting and a Gray code channel group for multi-turn counting; The vernier code channel group includes an M code channel, an N code channel and an S code channel, and the M code channel, the N code channel and the S code channel are all marked with a plurality of light-transmitting areas regularly distributed along the code channels; the Gray code channel group includes at least two Gray code channels, and the Gray code channels are all regularly distributed light and dark stripes; the indicator grating is provided with at least five code channels corresponding to the vernier code channel group and the Gray code channel group, and each code channel of the indicator grating is marked with a plurality of light-transmitting areas regularly distributed along the code channel; The vernier code channel group is located in the transmission area of ​​the scale grating, and the Gray code channel group is located in the transmission area and the reflection area of ​​the scale grating; The reflection area is located at the installation position of the scale grating and the rotating shaft.

2. The encoder based on the transmission and reflection scheme as claimed in claim 1, characterized in that: The N code channel, the M code channel and the S code channel are arranged sequentially from outside to inside, and the at least two Gray code channels are respectively placed between the M code channel and the N code channel, between the M code channel and the S code channel, outside the N code channel or inside the S code channel.

3. The encoder based on the transmission and reflection scheme as claimed in claim 1, characterized in that: It also includes an optical system for converting the light emitted by the light source into parallel light, and the optical system is placed between the light source and the scale grating.

4. The encoder based on the transmission and reflection scheme as claimed in claim 1, characterized in that: The scale grating is mounted on the rotating shaft by a light-absorbing adhesive.

5. The encoder based on the transmission and reflection scheme as claimed in claim 1, characterized in that: The installation position of the rotating shaft is subjected to an oxidation blackening treatment.

6. The encoder based on the transmission and reflection scheme as claimed in claim 1, characterized in that: It also includes a light absorbing plate, which is located at the installation position of the rotating shaft.

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