CN105910631B - Absolute grating scale and its measuring method - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000005259 measurement Methods 0.000 claims abstract description 140
- 238000012545 processing Methods 0.000 claims abstract description 35
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- 230000000737 periodic effect Effects 0.000 claims abstract description 6
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- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
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- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
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Abstract
The invention discloses absolute grating scale and its measuring method,The absolute grating scale includes source of parallel light module,Scale grating,Photodetector and signal processing module,Scale grating is provided with a basal orbit and multiple encoded tracks,Basal orbit includes a grating fringe inclined with measurement direction,It is in equably periodic arrangement and the grating fringe inclined with measurement direction that each encoded tracks, which include multiple,,And each encoded tracks have different cycles respectively,The collimated light beam that source of parallel light module is sent after scale grating by being irradiated on photodetector,Photodetector is used to collect the optical signal reached and is sent to signal processing module after being converted to measurement electric signal,Signal processing module is used for the measured value of the multiple encoded tracks of parsing acquisition after handling measurement electric signal and then calculating obtains Absolute position measurement value.Present invention etching difficulty is low, reduces manufacturing cost, and accuracy of measurement is high, can be widely applied in grating measuring industry.
Description
Technical field
The present invention relates to optical grating ruler measurement field, more particularly to absolute grating scale and its measuring method.
Background technology
Currently used grating scale can be divided into increment type grating scale, half absolute grating scale and absolute grating scale three
Kind, in Digit Control Machine Tool manufacturing extensive use.Increment type grating scale is the most frequently used high-accuracy measurement apparatus, and it has one absolutely
To zero mark, scale grating is equally spaced thereafter, and reading head moves with respect to scale grating, the More that the grid of process is formed
Striped can pass through Electric signal processing, obtain the distance of relative actual zero point.This measurement pattern is simple and easy, but in use,
Nearby re-scaled due to actual zero point must be returned to every time, so operating efficiency is difficult to greatly improve.To adapt to Digit Control Machine Tool
The needs of upgrading, half absolute grating scale are gradually generally used.Half absolute grating is set definitely on increment grating
Rail, a series of zero locatino gratings encoded with different distance are devised on absolute rail, by detecting adjacent zero locatino grating during use
Distance determine absolute position, greatly reduce the time of back to zero, improve operating efficiency, in addition, this kind of grating scale occurs
Alarm signal can also be sent to Digit Control Machine Tool immediately during failure, to ensure the security of processing.Recently, the appearance of absolute grating ruler
Triggered equipment manufacture revolutionary advancement, compared to half absolute grating scale, absolute coding grating scale has more advantages, due to
Any point has corresponding absolutely unique code value, so without cumulative errors, have Measurement Resolution height, strong antijamming capability,
The features such as stability is high, and non-liner revision can also be carried out.Other absolute coding scope is big, so measurable larger range
Linear displacement.The structure of absolute grating ruler is relatively easy, and its key point is the realization of absolute coding, and each is definitely compiled
Code correspond to an absolute position in grating ruler, and the absolute position of starting point to terminating point is subtracted each other and can be obtained by relatively
Displacement, avoid cumulative errors, the process for also eliminating retaking of a year or grade zero point.But the major defect of absolute grating scale is
Slower in high-acruracy survey speed, error code rate is high during decoding, moreover, grid line requirement on absolute grating scale coding code channel now
Spacing very little, and the higher grating spacing of the required accuracy just needs smaller, and cost of manufacture greatly improves, and this mode is present
The limitation of coding range, the expansion to measurement range bring limitation, and the fabrication error that grating code channel is small, it will make indivedual
Code channel shifts to an earlier date or delayed, and this can ultimately cause measurement error.
The content of the invention
In order to solve above-mentioned technical problem, it is an object of the invention to provide absolute grating scale and its measuring method.
The technical solution adopted for the present invention to solve the technical problems is：
Absolute grating scale, including source of parallel light module, scale grating, photodetector and signal processing module, it is described
Scale grating is provided with a basal orbit and multiple encoded tracks, and the basal orbit is inclined with measurement direction including one
The grating fringe of state, each encoded tracks include multiple equably in periodic arrangement and inclined with measurement direction
Grating fringe, and each encoded tracks have different cycles respectively, and the collimated light beam that the source of parallel light module is sent passes through mark
It is irradiated to after chi grating on photodetector, the photodetector is used to collect the optical signal reached and is converted to measurement telecommunications
Signal processing module is sent to after number, it is multiple that the signal processing module is used for parsing acquisition after handling measurement electric signal
The measured value and then calculating acquisition Absolute position measurement value of encoded tracks.
Further, the height all same of the basal orbit and each encoded tracks, each track have different measurements
Resolution ratio, and in adjacent track, the folder tangent of an angle of grating fringe and measurement direction on the higher track of Measurement Resolution
Value is equal to n times of the tangent value of the angle of the grating fringe and measurement direction on the relatively low track of Measurement Resolution, and wherein n is represented
The photosensitive first number and n=h/d, h of photodetector shared by each track represent the height of each track, and d represents neighboring photosensitive
Centre-to-centre spacing between member.
Further, the quantity of the encoded tracks totally two, respectively the first encoded tracks and the second encoded tracks, it is described
First encoded tracks include grating fringe multiple evenly distributed and with measurement direction in α angles, and second encoded tracks include
Grating fringe multiple evenly distributed and with measurement direction in β angles, the basal orbit, the first encoded tracks and the second coding rail
The height in road is h, and the grating fringe of the basal orbit and the angle of measurement direction are γ, and α, β and γ meet following relation：
Wherein, n represents photosensitive first number of the photodetector shared by each track and n=h/d, d represent neighboring photosensitive
Centre-to-centre spacing between member.
Further, the photodetector uses linear array cmos sensor or linear CCD sensor.
Another technical scheme is used by the present invention solves its technical problem：
The measuring method of described absolute grating scale, including step：
S1, scale grating is arranged on object under test, and drives object under test to move；
The collimated light beam that S2, source of parallel light are sent after scale grating by being irradiated on photodetector；
S3, photodetector collect the optical signal reached and are sent to signal processing module after being converted to measurement electric signal；
S4, parsing obtains basal orbit and multiple encoded tracks after signal processing module is handled measurement electric signal
Measured value and then calculating acquisition Absolute position measurement value.
Further, the step S4, is specifically included：
After S41, signal processing module pre-process to measurement electric signal, segmentation obtains and basal orbit and each coding rail
Multiple measurement image blocks corresponding to road；
S42, after carrying out edge detection process to multiple measurement image blocks respectively, obtain and collected in each measurement image block
The distance between encoded point and the bottom of corresponding encoded tracks；
S43, the projected length with reference to basal orbit and the grating fringe of each encoded tracks in the horizontal direction, calculate and obtain
Absolute position measurement value.
Further, the step S43, it is specially：
With reference to the projected length of basal orbit and the grating fringe of each encoded tracks in the horizontal direction, calculated according to following formula
Obtain Absolute position measurement value：
D=d0×(l0/h)+d1×(l1/h)+d2×(l2/h)+…+dn×(ln/h)
In above formula, d represents Absolute position measurement value, d0Represent basal orbit corresponding to measurement image block in encoded point with
The distance between bottom of the encoded tracks, d1Represent the encoded point and the volume in measurement image block corresponding to the first encoded tracks
The distance between bottom of code track, d2Represent the encoded point and the coding rail in measurement image block corresponding to the second encoded tracks
The distance between the bottom in road, dnRepresent the encoded point and the encoded tracks in measurement image block corresponding to the n-th encoded tracks
The distance between bottom, n are natural number, l0、l1、l2And lnBasal orbit, the first encoded tracks, the second coding rail are represented respectively
The projected length of road and the grating fringe of the n-th encoded tracks in the horizontal direction, h represent the height and l of each trackn/ h is represented
The grating fringe of corresponding code channel and the cotangent value of horizontal direction angle.
The beneficial effects of the invention are as follows：The absolute grating scale of the present invention, including source of parallel light module, scale grating, light
Electric explorer and signal processing module, scale grating, which is provided with a basal orbit and multiple encoded tracks, basal orbit, to be included
One grating fringe inclined with measurement direction, each encoded tracks include it is multiple equably in periodic arrangement and with survey
The inclined grating fringe in direction is measured, and each encoded tracks have different cycles respectively, source of parallel light module is sent flat
By being irradiated to after scale grating on photodetector, photodetector is used to collect the optical signal reached and is converted to row light beam
Signal processing module is sent to after measurement electric signal, signal processing module is used to after handling measurement electric signal parse to obtain
The measured value and then calculating acquisition Absolute position measurement value of multiple encoded tracks.This absolute grating scale is portrayed grating fringe
It is required that it is relatively low, grating etching difficulty is reduced, cost of manufacture is reduced, can effectively reduce grating error rate, reduce and be manufactured into
This, and accuracy of measurement is high.
The present invention another beneficial effect be：The measuring method of the absolute grating scale of the present invention, including step：S1, general
Scale grating is arranged on object under test, and drives object under test to move；The collimated light beam that S2, source of parallel light are sent passes through
It is irradiated to after scale grating on photodetector；S3, photodetector collect the optical signal reached and are converted to measurement electric signal
After be sent to signal processing module；S4, signal processing module to measurement electric signal handle after parsing obtain basal orbit and
The measured value and then calculating acquisition Absolute position measurement value of multiple encoded tracks.This measuring method is simple to operate, can be rapidly
Measurement result is obtained, and accuracy of measurement is high.
Brief description of the drawings
The invention will be further described with reference to the accompanying drawings and examples.
Fig. 1 is the structural representation of the absolute grating scale of the present invention；
Fig. 2 is the structural representation of the scale grating of the embodiment one of the absolute grating scale of the present invention；
Fig. 3 is the measurement image collected in the embodiment one of the absolute grating scale of the present invention to basal orbit；
Fig. 4 is the measurement figure collected in the embodiment one of the absolute grating scale of the present invention to the first encoded tracks
Picture；
Fig. 5 is the measurement figure collected in the embodiment one of the absolute grating scale of the present invention to the second encoded tracks
Picture.
Embodiment
Referring to Figures 1 and 2, the invention provides a kind of absolute grating scale, including source of parallel light module 1, scale grating
2nd, photodetector 3 and signal processing module 4, the scale grating 2 are provided with a basal orbit 10 and multiple encoded tracks,
The basal orbit 10 includes a grating fringe inclined with measurement direction, and each encoded tracks include multiple
It is in equably periodic arrangement and the grating fringe inclined with measurement direction, and each encoded tracks have different weeks respectively
Phase, the collimated light beam that the source of parallel light module 1 is sent after scale grating 2 by being irradiated on photodetector 3, the photoelectricity
Detector 3 is used to collect the optical signal reached and signal processing module 4 is sent to after being converted to measurement electric signal, at the signal
Reason module 4 is used to obtain definitely to measuring to parse to obtain the measured value of multiple encoded tracks and then calculate after electric signal is handled
Position measurements.
It is further used as the height all same of preferred embodiment, the basal orbit 10 and each encoded tracks, each institute
Stating track has different Measurement Resolutions, and in adjacent track, the grating fringe on the higher track of Measurement Resolution with
The tangent value of the angle of measurement direction is equal to the angle of the grating fringe and measurement direction on the relatively low track of Measurement Resolution
N times of tangent value, wherein n represent photosensitive first number of the photodetector 3 shared by each track and n=h/d, h represent each rail
The height in road, d represent the centre-to-centre spacing between neighboring photosensitive member.
It is further used as preferred embodiment, the quantity of the encoded tracks totally two, respectively the first encoded tracks
11 and second encoded tracks 12, first encoded tracks 11 include grating that is multiple evenly distributed and with measurement direction being in α angles
Striped, second encoded tracks 12 include grating fringe multiple evenly distributed and with measurement direction in β angles, the basic rail
The height in road 10, the first encoded tracks 11 and the second encoded tracks 12 is h, the grating fringe of the basal orbit 10 and measurement
The angle in direction is γ, and α, β and γ meet following relation：
Wherein, n represents photosensitive first number of the photodetector 3 shared by each track and n=h/d, d represent neighboring photosensitive
Centre-to-centre spacing between member.
Preferred embodiment is further used as, the photodetector 3 is passed using linear array cmos sensor or line array CCD
Sensor.
Present invention also offers a kind of measuring method of absolute grating scale, including step：
S1, scale grating 2 is arranged on object under test, and drives object under test to move；
The collimated light beam that S2, source of parallel light are sent after scale grating 2 by being irradiated on photodetector 3；
S3, photodetector 3 collect the optical signal reached and are sent to signal processing module after being converted to measurement electric signal
4；
Parsing acquisition basal orbit 10 and multiple coding rails after S4, signal processing module 4 are handled measurement electric signal
The measured value and then calculating acquisition Absolute position measurement value in road.
Preferred embodiment is further used as, the step S4, is specifically included：
After S41, signal processing module 4 pre-process to measurement electric signal, segmentation obtains and basal orbit 10 and each volume
Multiple measurement image blocks corresponding to code track；
S42, after carrying out edge detection process to multiple measurement image blocks respectively, obtain and collected in each measurement image block
The distance between encoded point and the bottom of corresponding encoded tracks；
S43, the projected length with reference to basal orbit 10 and the grating fringe of each encoded tracks in the horizontal direction, calculating obtain
Obtain Absolute position measurement value.
Preferred embodiment is further used as, the step S43, it is specially：
With reference to the projected length of basal orbit 10 and the grating fringe of each encoded tracks in the horizontal direction, according to following formula meter
Calculate and obtain Absolute position measurement value：
D=d0×(l0/h)+d1×(l1/h)+d2×(l2/h)+…+dn×(ln/h)
In above formula, d represents Absolute position measurement value, d0Represent the encoded point in measurement image block corresponding to basal orbit 10
The distance between bottom of the encoded tracks, d1Represent encoded point in measurement image block corresponding to the first encoded tracks 11 with
The distance between bottom of the encoded tracks, d2Represent the encoded point in measurement image block corresponding to the second encoded tracks 12 with being somebody's turn to do
The distance between bottom of encoded tracks, dnRepresent the encoded point and the coding in measurement image block corresponding to the n-th encoded tracks
The distance between bottom of track, n are natural number, l0、l1、l2And lnRespectively represent basal orbit 10, the first encoded tracks 11,
The projected length of the grating fringe of second encoded tracks 12 and the n-th encoded tracks in the horizontal direction, h represent the height of each track
Degree and lnThe cotangent value of the grating fringe and horizontal direction angle of code channel corresponding to/h expressions.
The present invention is elaborated below in conjunction with specific embodiment.
Embodiment one referring to Figures 1 and 2, a kind of absolute grating scale, including source of parallel light module 1, scale grating 2, light
Electric explorer 3 and signal processing module 4, scale grating 2 are provided with a basal orbit 10 and multiple encoded tracks, basal orbit
10 include a grating fringe inclined with measurement direction, and it is in equably periodic arrangement that each encoded tracks, which include multiple,
And the grating fringe inclined with measurement direction, and each encoded tracks have different cycles respectively, source of parallel light module 1 is sent out
By being irradiated to after scale grating 2 on photodetector 3, photodetector 3 is used to collect the light letter reached the collimated light beam gone out
Number and be sent to signal processing module 4 after being converted to measurement electric signal, signal processing module 4 is used at measurement electric signal
Parsing, which obtains the measured value of multiple encoded tracks and then calculated, after reason obtains Absolute position measurement value.
The height all same of basal orbit 10 and each encoded tracks, each track have different Measurement Resolutions, and adjacent
Track in, the tangent value of the angle of grating fringe and measurement direction on the higher track of Measurement Resolution is equal to measurement and differentiated
N times of the tangent value of the angle of grating fringe and measurement direction on the relatively low track of rate, wherein n are represented shared by each track
The photosensitive first number and n=h/d, h of photodetector 3 represent the height of each track, and d represents the center between neighboring photosensitive member
Away from.
In the present embodiment, the quantity of encoded tracks totally two, respectively the first encoded tracks 11 and the second encoded tracks 12,
First encoded tracks 11 include grating fringe multiple evenly distributed and with measurement direction in α angles, and the second encoded tracks 12 include
Grating fringe multiple evenly distributed and with measurement direction in β angles, basal orbit 10, the first encoded tracks 11 and the second coding rail
The height in road 12 is h, and the grating fringe of basal orbit 10 and the angle of measurement direction are γ, and α, β and γ meet following relation：
Wherein, n represents photosensitive first number of the photodetector 3 shared by each track and n=h/d, d represent neighboring photosensitive
Centre-to-centre spacing between member.
By that analogy, when the quantity of encoded tracks is three or more, the grating fringe and measurement direction of adjacent orbit
Angle tangent value between and n times of relation, the present invention will not enumerate.
In the present embodiment, photodetector 3 uses linear array cmos sensor or linear CCD sensor.Its linear array collection side
To the direction of motion perpendicular to absolute grating scale.Linear array images taken by photodetector 3 are a row perpendicular to absolute
The image of the direction of relative movement of formula grating scale.Assuming that exemplified by using sum of all pixels as 2048 linear CCD sensor, pixel is total
Number is that the pixel count that each track most multipotency is differentiated in 2048, then basal orbit and 2 encoded tracks is 2048/3.It should be noted
, the height in the present invention refers to the measurement of the vertical direction in Fig. 2, in fact, when scale grating 2 is kept flat, the direction
It can be described as width.
In more detail, in the present embodiment, the pixel center of linear CCD sensor is away from for 14 μm, number of pixels 2048, often
Individual track pixel shared on linear CCD sensor is 680 pixels.First encoded tracks 11 are that angle is α=45 degree
Oblique line, grid line width is 10 μm, and constantly repeats this oblique line in whole code channel code length.Second encoded tracks 12
For it is multiple evenly distributed and with the angled β of measurement direction grating fringe, first complete oblique line of the second encoded tracks 12 is (i.e.
Grating fringe) corresponding first encoded tracks 11 n cycle in all grating fringes, similarly the second encoded tracks 12 second
All grating fringes in the n cycle of corresponding first encoded tracks 11 of the complete oblique line of bar (i.e. grating fringe), according to this rule
Analogize.Basal orbit 10 only has a grating fringe, and its angle of inclination is γ, corresponding second encoded tracks 12 of the grating fringe
All grating fringes in n cycle.Above-mentioned n is each track number of pixels shared on linear CCD sensor, and its value is
680.Therefore, after using the present invention, between the first encoded tracks 11, the grating fringe of the second encoded tracks 12 portray spacing compared with
Greatly, substantially reduced so as to portray difficulty, reduce cost of manufacture, and the degree of accuracy of measurement can be improved, improved measurement and differentiate
Rate.
Every section of target point is all in 0 to 680 pictures to starting point a1, a2 of this section or a3 distance in Fig. 3, Fig. 4, Fig. 5
Between element, the absolute location information that the permutation and combination of the target point information of three tracks is included has 6803It is individual.By gathering back
The distance d come1、d2、d3Calculating, it can be deduced that specific Absolute position measurement value.Its computational methods is relatively simple, is advantageous to
Improve the processing speed of Absolute position measurement value.
When the position of linear CCD sensor collection is located at the high order end of scale grating 2, the grid line of 3 tracks exists respectively
At starting point a1, a2 and a3 of linear CCD sensor, i.e.,：Obtain coding (d corresponding to the coding zero point of absolute grating scale1,
d2,d3) it is (0,0,0).When grating scale scale grating moves, line array CCD gathers the raster image of three code channels, raster image
It is delivered to signal processing module and obtains d after treatment1、d2And d3。
The distance d to be returned by collection1、d2、d3Calculating, it can be deduced that specific absolute position values.Its computational methods compared with
To be simple, be advantageous to improve the processing speed of absolute position values.Absolute position values d formula of mathematical is：
D=d0×(l0/h)+d1×(l1/h)+d2×(l2/h)
The absolute position encoder corresponding to maximum absolute position in the present invention in 3 code channels is (680,680,680).Always
Code period is 6803, code length is that (680 × 680 × 680) × 10 μm are 314.4m.
Embodiment two, a kind of measuring method of absolute grating scale, including step：
S1, scale grating 2 is arranged on object under test, and drives object under test to move；
The collimated light beam that S2, source of parallel light are sent after scale grating 2 by being irradiated on photodetector 3；
S3, photodetector 3 collect the optical signal reached and are sent to signal processing module after being converted to measurement electric signal
4；
Parsing acquisition basal orbit 10 and multiple coding rails after S4, signal processing module 4 are handled measurement electric signal
The measured value and then calculating acquisition Absolute position measurement value in road, specifically include step S41~S43：
After S41, signal processing module 4 pre-process to measurement electric signal, segmentation obtains and basal orbit 10 and each volume
Multiple measurement image blocks corresponding to code track；
S42, after carrying out edge detection process to multiple measurement image blocks respectively, obtain and collected in each measurement image block
The distance between encoded point and the bottom of corresponding encoded tracks；
S43, the projected length with reference to basal orbit 10 and the grating fringe of each encoded tracks in the horizontal direction, calculating obtain
Absolute position measurement value is obtained, step S43 is specially：
With reference to the projected length of basal orbit 10 and the grating fringe of each encoded tracks in the horizontal direction, according to following formula meter
Calculate and obtain Absolute position measurement value：
D=d0×(l0/h)+d1×(l1/h)+d2×(l2/h)+…+dn×(ln/h)
In above formula, d represents Absolute position measurement value, d0Represent the encoded point in measurement image block corresponding to basal orbit 10
The distance between bottom of the encoded tracks, d1Represent encoded point in measurement image block corresponding to the first encoded tracks 11 with
The distance between bottom of the encoded tracks, d2Represent the encoded point in measurement image block corresponding to the second encoded tracks 12 with being somebody's turn to do
The distance between bottom of encoded tracks, dnRepresent the encoded point and the coding in measurement image block corresponding to the n-th encoded tracks
The distance between bottom of track, n are natural number, l0、l1、l2And lnRespectively represent basal orbit 10, the first encoded tracks 11,
The projected length of the grating fringe of second encoded tracks 12 and the n-th encoded tracks in the horizontal direction, h represent the height of each track
Degree and lnThe cotangent value of the grating fringe and horizontal direction angle of code channel corresponding to/h expressions, such as l0/ h represents basic code channel
The cotangent value of grating fringe and horizontal direction angle, l2/ h represents the grating fringe and horizontal direction angle of the second encoded tracks 12
Cotangent value.
Above is the preferable implementation to the present invention is illustrated, but the invention is not limited to embodiment, ripe
A variety of equivalent variations or replacement can also be made on the premise of without prejudice to spirit of the invention by knowing those skilled in the art, these
Equivalent modification or replacement is all contained in the application claim limited range.
Claims (7)
1. absolute grating scale, it is characterised in that including source of parallel light module, scale grating, photodetector and signal transacting
Module, the scale grating are provided with a basal orbit and multiple encoded tracks, and the basal orbit includes one and measurement
The inclined grating fringe in direction, it is in equably periodic arrangement and and measurement direction that each encoded tracks, which include multiple,
Inclined grating fringe, and each encoded tracks have different cycles respectively, the source of parallel light module sends parallel
By being irradiated to after scale grating on photodetector, the photodetector is used to collect the optical signal reached and conversion light beam
To be sent to signal processing module after measurement electric signal, the signal processing module is used to after handling measurement electric signal solve
Analysis, which obtains the measured value of multiple encoded tracks and then calculated, obtains Absolute position measurement value.
2. absolute grating scale according to claim 1, it is characterised in that the basal orbit and the height of each encoded tracks
All same is spent, each encoded tracks have different Measurement Resolutions, and in adjacent track, the higher rail of Measurement Resolution
The tangent value of the angle of grating fringe and measurement direction on road be equal to grating fringe on the relatively low track of Measurement Resolution with
N times of the tangent value of the angle of measurement direction, wherein n represent the photosensitive first number and n of the photodetector shared by each track
=h/d, h represent the height of each track, and d represents the centre-to-centre spacing between neighboring photosensitive member.
3. absolute grating scale according to claim 1, it is characterised in that the quantity of the encoded tracks totally two, point
Not Wei the first encoded tracks and the second encoded tracks, first encoded tracks include multiple evenly distributed and with measurement direction are in
The grating fringe at α angles, second encoded tracks include grating fringe multiple evenly distributed and with measurement direction in β angles, institute
The height for stating basal orbit, the first encoded tracks and the second encoded tracks is h, the grating fringe of the basal orbit and measurement
The angle in direction is γ, and α, β and γ meet following relation：
<mfenced open = "{" close = "">
<mtable>
<mtr>
<mtd>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mi>&beta;</mi>
<mo>=</mo>
<mi>n</mi>
<mi> </mi>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mi>&gamma;</mi>
</mtd>
</mtr>
<mtr>
<mtd>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mi>&alpha;</mi>
<mo>=</mo>
<mi>n</mi>
<mi> </mi>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mi>&beta;</mi>
<mo>=</mo>
<msup>
<mi>n</mi>
<mn>2</mn>
</msup>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mi>&gamma;</mi>
</mtd>
</mtr>
</mtable>
</mfenced>
Wherein, n represents photosensitive first number of the photodetector shared by each track and n=h/d, d represent neighboring photosensitive member
Between centre-to-centre spacing.
4. absolute grating scale according to claim 1, it is characterised in that the photodetector is passed using linear array CMOS
Sensor or linear CCD sensor.
5. the measuring method of the absolute grating scale described in claim 1, it is characterised in that including step：
S1, scale grating is arranged on object under test, and drives object under test to move；
The collimated light beam that S2, source of parallel light are sent after scale grating by being irradiated on photodetector；
S3, photodetector collect the optical signal reached and are sent to signal processing module after being converted to measurement electric signal；
Parsing obtains the measurement of basal orbit and multiple encoded tracks after S4, signal processing module are handled measurement electric signal
It is worth and then calculates and obtains Absolute position measurement value.
6. the measuring method of absolute grating scale according to claim 5, it is characterised in that the step S4, specific bag
Include：
After S41, signal processing module pre-process to measurement electric signal, segmentation obtains and basal orbit and each encoded tracks pair
The multiple measurement image blocks answered；
S42, after carrying out edge detection process to multiple measurement image blocks respectively, obtain the volume collected in each measurement image block
The distance between code-point and bottom of corresponding encoded tracks；
S43, the projected length with reference to basal orbit and the grating fringe of each encoded tracks in the horizontal direction, calculate and obtain definitely
Position measurements.
7. the measuring method of absolute grating scale according to claim 6, it is characterised in that the step S43, its is specific
For：
With reference to the projected length of basal orbit and the grating fringe of each encoded tracks in the horizontal direction, calculated and obtained according to following formula
Absolute position measurement value：
D=d0×(l0/h)+d1×(l1/h)+d2×(l2/h)+…+dn×(ln/h)
In above formula, d represents Absolute position measurement value, d0Represent the encoded point and the volume in measurement image block corresponding to basal orbit
The distance between bottom of code track, d1Represent the encoded point and the coding rail in measurement image block corresponding to the first encoded tracks
The distance between the bottom in road, d2Represent the encoded point and the encoded tracks in measurement image block corresponding to the second encoded tracks
The distance between bottom, dnRepresent the encoded point in measurement image block corresponding to the n-th encoded tracks and the bottom of the encoded tracks
The distance between, n is natural number, l0、l1、l2And lnRespectively represent basal orbit, the first encoded tracks, the second encoded tracks and
The projected length of the grating fringe of n-th encoded tracks in the horizontal direction, h represent the height and l of each trackn/ h represents corresponding
Code channel grating fringe and horizontal direction angle cotangent value.
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| US10295378B2 (en) * | 2017-06-29 | 2019-05-21 | Mitutoyo Corporation | Contamination and defect resistant optical encoder configuration outputting structured illumination to a scale plane for providing displacement signals |
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| CN108151658B (en) * | 2018-01-24 | 2023-08-11 | 清华大学深圳研究生院 | Device and method for judging absolute position of reference point of grating ruler |
| CN108362208B (en) * | 2018-04-02 | 2024-04-05 | 广州数控设备有限公司 | Pseudo-random code channel grating ruler and reading method thereof |
| JP2020056786A (en) * | 2018-09-28 | 2020-04-09 | 株式会社ミツトヨ | Optical rotary encoder |
| CN110646171B (en) * | 2019-10-31 | 2021-11-02 | 中国科学院长春光学精密机械与物理研究所 | Method for measuring parallelism of light source |
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