JPH0678816U - Absolute encoder - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a small-sized and inexpensive absolute encoder that does not require strict positioning accuracy, is easy to assemble and adjust, and simplifies mechanical play prevention. [Structure] The code rows C, D, and E of the code plate 1 have different combinations of light and shade bands depending on the position, but A and B have a constant pattern regardless of the position in the moving direction (A is white, B is black). Has become. Each of the readers P _{0 to} P ₁₁ is ½ of the unit width of the code string
The reader row 2 arranged with 12 equal intervals in parallel moves up and down on the matching plate. Assuming that each reader outputs 0 when reading white and outputs 1 when reading black, P ₁₁ is always 0 and P ₁₀ is always 1 in the illustrated positional relationship. Even if the positioning shifts and the reader moves one position to the left, the signals are actually read from the left end, and the third position from the position where it first changed from 0 to 1 is set to C row, and every other row from that position. If the data is adopted for, the C, D, and E codes can be correctly read without knowing how the position is displaced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an absolute encoder that converts position and angle into electrical codes.

[0002]

[Prior art]

 It has been widely used as a means to realize an absolute encoder from the conventional method of arranging as many code strings as the required resolution in parallel to the direction of relative movement and reading these in parallel to code the position and angle. This is a technology that is being carried out. As the code, a gray code in which two or more of the code strings do not change at the same time is mainly used. In this case, the minimum unit of gray code change is the resolution, so if a high resolution is required for an absolute encoder using this method, it is necessary to produce a fine code string and read it accurately. The reader row must be positioned and strictly maintained during use. For this reason, the high-resolution absolute encoder has the drawbacks that it takes time and effort to assemble and adjust, the mechanism becomes large to prevent rattling during use, and the price becomes expensive.

[0003]

[Problems to be solved by the device]

 The present invention does not require strict positioning accuracy, is easy to assemble and adjust, simplifies mechanical backlash prevention, and is small in size and inexpensive to manufacture. And to provide an absolute encoder with resolution.

[0004]

[Means for Solving the Problems]

 In the present invention, in order to solve the above-mentioned problems, as the code plate, a code plate in which a part of a plurality of code sequences has a fixed pattern regardless of the position is used, and it is redundant with respect to the number of bits to be read. The problem is to try to solve it by detecting it with a reader that has a certain property. That is, according to the present invention, a code plate having a plurality of code rows parallel to the relative movement direction and a part of which has a constant pattern regardless of the position, and a code board having at least twice the code rows. A rotary or linear absolute encoder is provided, which comprises a reader train.

[0005]

【Example】

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 schematically shows the basic construction of a linear absolute encoder according to the present invention. In the figure, 1 denotes a plywood, which is an 8-position 3-bit type. Reference numeral 2 is a reader array, and points having sensitivity (each reader P ₀ ... P ₁₁ ) are indicated by circles. In practice, the reader row 2 moves up and down on the plywood 1 in parallel. The combination of the light and shade bands of the code strings C, D, and E of the code plate 1 changes depending on the position, but the code strings A and B have a constant pattern (white for the code A, regardless of the position in the moving direction (vertical direction)). The code B is black). Further, each of the readers P _0, ..., P ₁₁ of the reader array 2 is arranged at a half interval of the unit width of the code array and at 12 equal intervals.

[0006]

[Function of the device]

In FIG. 1, if the readers P _0, ..., P ₁₁ of the reader array 2 output 0 when reading white and 1 when reading black, in the positional relationship shown in the figure, P ₁₁ is always 0 and P ₁₀ should always be 1. However, if the reading row 2 is misaligned and one reading device is moved to the left, P ₁₁ and P ₁₀ are always 0, and P ₉ is always 1. Actually, the output signal is read in order from the left end of the reader row 2, and the third row from the position where it first changed from 0 to 1 is set to C row, and every other data from that row is adopted, how is it done? The code of C, D, E can be read correctly without knowing whether the position is shifted. In the state of FIG. 1, since P ₁₀ becomes the first 1, P ₇ = C, P ₅ = D, and P ₃ = E.

The above description has been made by taking a linear encoder as an example, but if the code strings are arranged on concentric circles, a rotary encoder is obtained. Further, the recording of the plywood can be either optical or magnetic, if combined with an appropriate reader. From the above, it was shown that it is possible to realize an absolute encoder that does not require high-accuracy positioning of the reader row and that has the same reading accuracy as conventional ones.

[0008]

[Effect of device]

 As described above, according to the absolute encoder of the present invention, it is not necessary to precisely position the code plate and the reader. Therefore, it does not take time and effort to assemble and adjust. Also, since there is no backlash during use, the mechanism can be simplified, and the size and cost can be reduced. The absolute encoder of the present invention requires more readers than conventional encoders, but CCD image sensors, photodiode arrays, and other parts that can read multiple points with one element have been put to practical use. , This is not a drawback. Rather, it is possible to reduce the size with integrated elements, and it is also possible to confirm that the code string has been read correctly by providing redundancy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a basic configuration of an absolute encoder of the present invention.

[Explanation of symbols]

 1 plywood, 2 reader rows

Claims (1)

[Scope of utility model registration request] 1. A code plate having a plurality of code rows parallel to the relative movement direction, and a part of which has a constant pattern regardless of the position, and at least twice as many reader rows as the code rows. A rotary or linear absolute encoder characterized by having.