CN215893646U - High-calibration margin encoder - Google Patents

Abstract

The utility model provides a high calibration margin encoder, comprising: the device comprises a scale grating, an indication grating, a photoelectric receiver and a light source; the scale grating is provided with a vernier code channel group for single-circle counting and a Gray code channel group for multi-circle counting, and the Gray code channel group comprises at least two Gray code channels; according to the utility model, the calibration margin of the encoder is improved by increasing the number of Gray code channels, so that the fault-tolerant capability of the encoder is improved, and the encoder can work normally under different working conditions; the utility model also adopts a blue light source, increases the effective light-emitting radius of the light source, improves the light-emitting efficiency and improves the reliability of the encoder.

Description

High-calibration margin encoder

Technical Field

The utility model relates to the field of encoders, in particular to a high-calibration margin encoder.

Background

The photoelectric encoder is a digital checking device integrating light, machine and electricity into one body, it is a sensor which can convert the mechanical and geometric displacement quantity transferred to the shaft into pulse or digital quantity by means of photoelectric conversion circuit, and is mainly used for detecting speed or position. The method has the advantages of high precision, quick response, stable and reliable performance and the like.

The photoelectric encoder can adopt vernier type coding, the vernier type coding is coded according to the principle of vernier caliper, namely 3 circles of code channels are engraved on the scale grating and respectively marked as N (vernier code channel), M (main code channel) and S (segment code channel), and certain phases are staggered between the code channels in sequence.

When a vernier coding mode is adopted, theoretically, zero positions of M, S, N three code channels are at the same fixed position, and in the rotation process of the scale grating, the zero positions of the three code channels start and end together, but due to the existence of scale grating deformation caused by part processing errors, installation errors and temperature, the three code channels cannot be guaranteed at the same position, so that synchronous operation needs to be carried out on the three code channels, the synchronous operation process is a calibration process, the maximum allowable calibration range is a calibration tolerance, the range of the calibration tolerance is reduced along with the improvement of the number of the encoder, the larger the calibration margin is, and the more reliable the performance of the encoder is.

Therefore, with the market demand of the encoder with miniaturization and high precision, how to increase the calibration margin range is a technical problem that needs to be solved by those skilled in the art at present.

In the existing encoder based on the transmission type principle, the LED light sources of the encoder are all infrared light or red light, the light emitting wavelength of the light sources is longer, the light emitting efficiency is lower, and when the width of a window scribed on a grating is less than 0.025mm, signals are unstable due to low photoelectric conversion efficiency.

The standard size of a tube shell adopted by the existing small-sized packaged LED is phi 4.7mm, when the internal light emitting chip is infrared light or red light, the effective radius of the emitted light is only phi 2.9mm to 3mm, and the area of an effective scribing area of the grating is limited.

The existing high-resolution optical system is solved by double light-emitting systems and large-package LEDs (phi 6mm, phi 7mm and the like), so that the size of a product is increased, and miniaturization cannot be realized.

SUMMERY OF THE UTILITY MODEL

The present invention provides a high calibration margin encoder to solve the above problems.

In order to achieve the purpose, the utility model adopts the following specific technical scheme:

a high scaling margin encoder, comprising: the device comprises a scale grating, an indication grating, a photoelectric receiver and a light source; the scale grating is provided with a vernier code channel group for single-circle counting and a Gray code channel group for multi-circle counting;

the vernier code channel group comprises an M code channel, an N code channel and an S code channel, wherein a plurality of light-transmitting areas which are regularly distributed along the code channel are engraved on the M code channel, the N code channel and the S code channel, the Gray code channel group comprises at least two Gray code channels, and each Gray code channel is light and dark alternate stripes which are regularly distributed; the indication grating is provided with at least five code channels corresponding to the cursor code channel group and the Gray code channel group, and each code channel of the indication grating is engraved with a plurality of light-transmitting areas regularly distributed along the code channel;

the calibration margin of the encoder is in inverse proportion to the use bits of the N code channels in the binary signal output by the encoder, the use bits of the N code channels in the binary signal output by the encoder are reduced by increasing the number of the Gray code channels, and the calibration margin of the encoder is further improved.

Preferably, the light source is a blue light source.

Preferably, the N code channel, the M code channel and the S code channel are sequentially arranged from outside to inside, and at least two gray code channels are respectively disposed between the M code channel and the N code channel, between the M code channel and the S code channel, outside of the N code channel or inside of the S code channel.

Preferably, the geometric centers of the M code channel, the N code channel, the S code channel and all the Gray code channels on the scale grating are superposed; indicating that the geometric centers of all the code tracks on the grating coincide.

Preferably, the geometric center of the minimum circumcircle of all the tracks of the indication grating coincides with the geometric center of the M track.

Preferably, the diameter of the smallest circumscribed circle is smaller than the effective light emitting diameter of the light source.

Preferably, the radial dimension of each track of the indication grating is smaller than the radial dimension of the corresponding track on the scale grating.

Preferably, the optical system is arranged between the light source and the scale grating.

The utility model can obtain the following technical effects:

(1) the calibration margin of the encoder is improved by increasing the number of Gray code channels, so that the fault-tolerant capability of the encoder is improved, and the encoder can work normally under different working conditions;

(2) and the blue light source is adopted, so that the effective light emitting radius of the light source is increased, the light emitting efficiency is improved, and the reliability of the encoder is improved.

Drawings

Fig. 1 is a schematic structural diagram of a high calibration margin encoder according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a structure of a scale grating according to an embodiment of the utility model;

FIG. 3 is a schematic diagram of a structure of an indicator grating according to an embodiment of the utility model;

fig. 4 is a schematic structural diagram of an optical receiver according to an embodiment of the present invention.

Wherein the reference numerals include: a scale grating 1, an indication grating 2, a photoelectric receiver 3, a light source 4, a rotating shaft 5, an M code channel 101, an N code channel 102, an S code channel 103, a first Gray code channel 104, a second Gray code channel 105, a third Gray code channel 106, a fourth Gray code channel 107, an indication grating M code channel 201, an indication grating N code channel 202, an indication grating S code channel 203, an indication grating first Gray code channel 204, an indication grating second Gray code channel 205, an indication grating third Gray code channel 206, an indication grating fourth Gray code channel 207, an M code channel optical signal receiving window 301, an N code channel optical signal receiving window 302, an S code channel optical signal receiving window 303, a first Gray code channel optical signal receiving window 304, a second Gray code channel optical signal receiving window 305, a third Gray code channel optical signal receiving window 306, a fourth Gray code channel optical signal receiving window 307, a minimum circumscribed circle 6 and an effective light-emitting diameter 7.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not to be construed as limiting the utility model.

As shown in fig. 1, an embodiment of the present invention provides a high scaling margin encoder, including: the device comprises a scale grating 1, an indication grating 2, a photoelectric receiver 3 and a light source 4; the scale grating 1 is provided with a vernier code channel group for single-circle counting and a Gray code channel group for multi-circle counting;

light emitted by the light source 4 sequentially penetrates through the light-transmitting area of the scale grating 1 and the light-transmitting area of the indication grating 2 to be received by the photoelectric receiver 3, the light is converted into an electric signal through processing such as amplification, shaping and filtering and then output, and the rotation angle of a rotating shaft 5 provided with an encoder is obtained according to the output electric signal;

as shown in fig. 3, the lower surface of the optical receiver 3 is provided with a plurality of optical signal receiving windows, which respectively correspond to the vernier code channel group and the gray code channel group, and include an M-code channel optical signal receiving window 301, an N-code channel optical signal receiving window 302, an S-code channel optical signal receiving window 303, a first gray code channel optical signal receiving window 304, a second gray code channel optical signal receiving window 305, a third gray code channel optical signal receiving window 306, and a fourth gray code channel optical signal receiving window 307.

When the scale grating 1 rotates, the shielding condition of the light source 4 is changed by the vernier track group and the gray track group, the incident light signal is cut into a signal with variable intensity, the intensity of the light received by the photoelectric receiver 3 is changed, and further the electric signal output by the photoelectric receiver 3 is changed.

As shown in fig. 2, the cursor track group includes an M code track 101, an N code track 102, and an S code track 103, where the M code track 101, the N code track 102, and the S code track 103 are all engraved with a plurality of light-transmitting regions regularly distributed along the code track, so that the M code track 101, the N code track 102, and the S code track 103 are all light-dark stripes, where the light-transmitting regions are light stripes, and the light-opaque regions are dark stripes; the gray code channel group includes at least two gray code channels, each gray code channel is a regularly distributed bright and dark alternate stripe, in this embodiment, the gray code channel group includes four gray code channels, which are a first gray code channel 104, a second gray code channel 105, a third gray code channel 106, and a fourth gray code channel 107, respectively;

the indication grating 2 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 indication grating 2 is engraved with a plurality of light transmission areas regularly distributed along the code channel, so that each code channel of the indication grating 2 is also light and dark stripes, wherein the light transmission areas are bright stripes, and the light transmission positions are dark stripes;

as shown in fig. 3, in the present embodiment, the indication grating 2 is provided with seven code channels, which are an indication grating M code channel 201, an indication grating N code channel 202, an indication grating S code channel 203, an indication grating first gray code channel 204, an indication grating second gray code channel 205, an indication grating third gray code channel 206, and an indication grating fourth gray code channel 207, respectively;

the calibration margin of the encoder is inversely proportional to the used bits of the N-code channel 102 in the binary signal output by the encoder, i.e. the less the used bits of the N-code channel 102 in the binary signal output by the encoder, the greater the calibration margin of the encoder; the number of gray code channels is increased to reduce the used bits of the N code channels 102 in the binary signal output by the encoder, thereby improving the calibration margin of the encoder.

When cursor operation is performed according to the M code channel 101, the N code channel 102, and the S code channel 103 to obtain the encoder output together, the encoder is an absolute encoder, and when the encoder output is obtained according to any one of the M code channel 101, the N code channel 102, and the S code channel 103, the encoder is an incremental encoder.

In one embodiment of the present invention, the light source 4 is a blue light source, and the blue light source has a light emitting efficiency improved by 10-15% compared to infrared light or red light, and a light emitting radius increased to 3.3-3.4 mm.

In one embodiment of the present invention, the N code channel 102, the M code channel 101, and the S code channel 103 are sequentially arranged from outside to inside, and at least two gray code channels are disposed between the M code channel 101 and the N code channel 102, between the M code channel 101 and the S code channel 103, outside of the N code channel 102, or inside of the S code channel 103; the position of the Gray code channel has no influence on the effect of the Gray code, and can be set according to the actual condition of the scale grating 1.

In one embodiment of the utility model, the geometric centers of the M code channel 101, the N code channel 102, the S code channel 103 and all the gray code channels on the scale grating 1 coincide, indicating that the geometric centers of all the code channels on the grating 2 coincide; each code channel is an annular code channel, the geometric center of the annular code channel is the center of a circle, namely the centers of the circles of all the code channels on the scale grating 1 coincide, and the centers of the circles of all the code channels on the indication grating 2 coincide.

In one embodiment of the present invention, the geometric center of the minimum circumscribed circle 6 of all the code channels of the indication grating 2 coincides with the geometric center of the M code channel 101, i.e., the centers of all the code channels on the scale grating 1 coincide with the centers of all the code channels on the indication grating 2.

In one embodiment of the utility model, the diameter of the minimum circumscribed circle 6 is less than the effective light emitting diameter 7 of the light source 4; it is ensured that all tracks on the indication grating 2 are within the illumination range of the light source 4.

In one embodiment of the utility model, the radial dimension of each track of the indication grating 2 is smaller than the radial dimension of the corresponding track on the scale grating 1.

In one embodiment of the present invention, an optical system for converting light emitted from the light source 4 into parallel light is further included, the optical system being disposed between the light source 4 and the scale grating 1; the light is uniformized by converting the light into parallel light, so that the light intensity of the light irradiated to the scale grating 1 is uniform.

The advantages of the utility model are explained in detail below:

the calibration value of the encoder is obtained through vernier calculation according to the phase deviation of the S code channel 103 and the N code channel 102 relative to the M code channel 101, and the larger the position phase deviation of the S code channel 103 and the N code channel 102 relative to the M code channel 101 is, the larger the calibration value is; under the unchangeable prerequisite of encoder overall structure, when the temperature variation, expend with heat and contract with cold appears in the material, and the skew appears in the relative position of scale grating 1 and photoelectric receiver 3 promptly, leads to the calibration value increase of encoder, and when the calibration value is greater than or equal to the demarcation tolerance, the encoder warning can not normal operating promptly, therefore the improvement of the demarcation allowance of encoder can improve the temperature adaptability of encoder.

In the case of counting a single turn of the encoder, N code channel 102 and S code channel 103 need to be synchronized with M code channel 101, and therefore, it is necessary to provide synchronization bits, and the more the number of synchronization bits is, the easier the synchronization is, but the encoder accuracy decreases as the number of synchronization bits increases, and in the present invention, the number of synchronization bits c is 4.

The required physical mark number of the M code channel 101 is 2^aThat is, the physical bit number output by the encoder is a bits, and the number of pulses of the M-code channel 101 in each electrical cycle is 2^n+sThe number of pulses of the N code channel 102 is 2^n+s1, the number of pulses of S-code channel 103 is 2^n+s-2^sEquation (1) can be derived from the encoder principle:

a＝n+s+b (1)

wherein N is the number of bits used by the N code channel 102 in the output electrical signal, S is the number of bits used by the S code channel 103 in the output electrical signal, and b is the number of gray code channels included in the gray code channel group; since the bits used in the N code track 102 are the encoder high bits, N-s or N-s +1 is usually used to reduce the probability of error in the encoder reading.

The formula for calculating the calibration margin of the encoder is as the formula (2):

K＝±7(360°/2^n+c) (2)

wherein K is the calibration allowance of the encoder;

as can be seen from the equations (1) and (2), under the condition that the number of the M code channel 101, the N code channel 102, and the S code channel 103 is not changed, the number of the gray code channels is increased, so that the calibration margin of the encoder can be effectively increased.

The utility model can be applied to the development of a high-resolution and high-precision encoder, and in one embodiment of the utility model, the number of the M code channels 101 of the scale grating 1 is 2048P/r, namely, the number of bits a of the electric signal output by the encoder is 11 bits.

N-s-4 is selected, and the pulse number of the M code channel 101 is 2 in each electrical period of the scale grating 1⁴⁺⁴The number of pulses of the N code channel 102 is 2⁴⁺⁴The pulse numbers of-1 and S-code channel 103 are respectively 2⁴⁺⁴-2⁴And according to the calculated number b of Gray code channels being 3.

The encoder calibration margin K is calculated to be +/-9.84 degrees, which is 2 times of the calibration margin of the encoder of the current transmission scheme.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be taken as limiting the utility model. Variations, modifications, substitutions and alterations of the above-described embodiments may be made by those of ordinary skill in the art without departing from the scope of the present invention.

The above embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims (8)

1. A high scaling margin encoder, comprising: the device comprises a scale grating, an indication grating, a photoelectric receiver and a light source; the scale grating is provided with a vernier code channel group for single-circle counting and a Gray code channel group for multi-circle counting;

the vernier code channel group comprises an M code channel, an N code channel and an S code channel, wherein a plurality of light-transmitting areas which are regularly distributed along the code channel are engraved in the M code channel, the N code channel and the S code channel, the Gray code channel group comprises at least two Gray code channels, and each Gray code channel is a light and dark alternate stripe which is regularly distributed; the indication grating is provided with at least five code channels corresponding to the cursor code channel group and the Gray code channel group, and each code channel of the indication grating is engraved with a plurality of light-transmitting areas regularly distributed along the code channel;

the calibration margin of the encoder is inversely proportional to the used bits of the N code channels in the binary signal output by the encoder, and the used bits of the N code channels in the binary signal output by the encoder are reduced by increasing the number of the Gray code channels, so that the calibration margin of the encoder is improved.

2. The high calibration margin encoder of claim 1, wherein the light source is a blue light source.

3. The high calibration margin encoder of claim 1, wherein the N, M, and S code channels are sequentially arranged from outside to inside, and the at least two gray code channels are respectively disposed between the M and N code channels, between the M and S code channels, outside the N code channels, or inside the S code channels.

4. The high calibration margin encoder of claim 1, wherein geometric centers of the M, N, S, and all gray tracks on the scale grating coincide; the geometric centers of all code channels on the indication grating are coincident.

5. The high calibration margin encoder of claim 1, wherein a geometric center of a minimum circumcircle of all code tracks of the indication grating coincides with a geometric center of the M code tracks.

6. The high calibration margin encoder of claim 5, wherein a diameter of the minimum circumscribing circle is less than an effective light emitting diameter of the light source.

7. The high calibration margin encoder of claim 1, wherein each track of the indication grating has a radial dimension that is less than a radial dimension of a corresponding track on the scale grating.

8. The high calibration margin encoder of claim 1, further comprising an optical system for converting light emitted from the light source into parallel light, the optical system being disposed between the light source and the scale grating.

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