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Absolute position length measurement type encoder

a technology of absolute position length and encoder, which is applied in the direction of converting sensor output optically, instruments, measurement devices, etc., can solve the problems of reducing the degree of freedom of selection of light-receiving elements, adversely affecting the size and performance of absolute position length measurement type encoder, and the production cost. , to achieve the effect of reducing the minimum line width, reducing the cost of production, and reducing the accuracy

Active Publication Date: 2011-07-19
MITUTOYO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0036]According to the present invention, where the minimum line width PABS of the ABS pattern is not an integral multiple of the array interval PPDA of the ABS light-receiving element array, a finer interval than the array interval PPDA may be made into a minimum resolution power, wherein the moving distance can be measured without lowering the accuracy. Therefore, the degree of freedom in design of the minimum line width of the ABS pattern and range of selection of the light-receiving element can be widened, wherein it becomes possible to compose an absolute position length measurement type encoder having a greater degree of freedom with respect to the size, performance and cost thereof.
[0037]Also, an absolute position length measurement type encoder can be composed, which, where an arithmetic operation for correlation is carried out, is robust and capable of correctly measuring the moving distance even if there is an error in output of the ABS light-receiving element array.
[0038]In particular, where the interval D is the maximum real number value that satisfies the expressions (1) and (2), it becomes possible to quickly measure the moving distance at a further higher accuracy without increasing the arithmetic operation amount more than necessary.

Problems solved by technology

However, there is a restriction in the array interval of the ABS light-receiving element array, freedom for selection of the light-receiving elements was necessarily reduced.
Also, the degree of freedom in design for the minimum line width of the ABS pattern could not be sufficiently secured.
As a result, there is a problem in that adverse influences are given to the size and performance of the absolute position length measurement type encoder and to the production cost thereof.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

embodiment 1

[0051]Embodiment 1 according to the present invention will be described using FIG. 1 through FIG. 4. FIG. 1 is a schematic view showing the entirety of an absolute position length measurement type encoder of the present invention, FIG. 2 is a perspective view schematically showing the relationship between a light-emitting element, a scale and a light-receiving element, and FIG. 3 is a schematic view showing the scale, FIG. 4 is a schematic view of a light-receiving element.

[0052]First, a brief description is given of the entire configuration of the present embodiment.

[0053]Mainly as shown in FIG. 1, an absolute position length measurement type encoder 100 includes

[0054]a scale 102 (Refer to FIGS. 2 and 3) in which an ABS pattern 104 based on a pseudorandom code is provided,

[0055]a light-receiving element 112 for receiving bright and dark patterns formed by the scale 102 and

[0056]a signal processing circuit 118 for processing signals subjected to output of the light-receiving elemen...

embodiment 2

[0083]Next, a description is given of Embodiment 2 according to the present invention with reference to FIG. 5 through FIG. 7.

[0084]FIG. 5 is a schematic view showing the entirety of an absolute position length measurement type encoder according to Embodiment 2, FIG. 6 is a flowchart showing actions from a space-dividing number conversion circuit to a position data synthesizing circuit, and FIG. 7 is a schematic view showing signals corresponding to respective steps of FIG. 6.

[0085]As shown in FIG. 5, the absolute position length measurement type encoder 101 has a configuration similar to the absolute position length measurement type encoder 100 as the entirety according to Embodiment 1. However, the encoder 101 differs from the encoder 100 in that the signal processing circuit 119 includes an edge position detection circuit 128, a peak position detection circuit 130, and a decoding circuit 132 in the front stage of a correlation circuit 134, and includes a position data synthesizin...

embodiment 3

[0107]In the above-described embodiments, it was configured that bright and dark patterns are imaged all in the X-axis direction of the ABS light-receiving element array 114 by a single lens 110. However, the present invention is not limited thereto. For example, shown in FIG. 8, it may be possible that a lens array in which a plurality of minor lenses 109A through 109E are juxtaposed in the lens 109 is used. In this case, since images 111 of bright and dark patterns are left-right reversed on the ABS light-receiving element array 115, it is necessary that the reading direction of image data is reversed to the moving direction for each of the minor array 115A through 115E of the ABS light-receiving element array 115. However, since the ABS pattern 104 and the ABS light-receiving element array 115 may be disposed in proximity to each other, the absolute position length measurement type encoder itself can be thinned, and can be made durable against disturbance.

[0108]Also, in the abov...

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PUM

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Abstract

An absolute position length measurement type encoder includes: a scale in which an ABS pattern based on a pseudorandom code is provided; a light-receiving element for receiving bright and dark patterns formed by the scale; and a signal processing circuit for processing signals subjected to output of the light-receiving element and measuring an absolute position of the scale to the light-receiving element, wherein the signal processing circuit includes a space-dividing number conversion circuit that obtains finer intervals D than the array interval PPDA of the ABS light-receiving element array of the light-receiving element, and simultaneously obtains and outputs a digital value for each of the intervals D subjected to output of the ABS light-receiving element array. Therefore, even where the minimum line width of the ABS pattern is not an integral multiple of the array interval of the ABS light-receiving element array, an arithmetic operation for the correlation can be carried out, and the moving distance can be measured at high accuracy.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The disclosure of Japanese Patent Application No. 2008-125631 filed on May 13, 2008 including specifications, drawings and claims is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an absolute position length measurement type encoder that includes a scale in which an ABS pattern based on a pseudorandom code is provided, a light-receiving element for receiving bright and dark patterns formed by the scale, and a signal processing circuit for processing signals in compliance with output of the light-receiving element and measuring an absolute position of the scale with respect to the light-receiving element, and in particular to an absolute position length measurement type encoder capable of measuring a moving distance at high accuracy by arithmetic operations for correlation without being influenced by an array interval of ABS light-receiving el...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01D5/36
Inventor MORIMOTO, KOUJI
Owner MITUTOYO CORP