JPH07229762A - Absolute value encoder - Google Patents

Abstract

PURPOSE:To obtain N pieces of absolute position data having the same resolution not overlapping perfectly to the N pieces of absolute position data, by obtaining N pieces of absolute position data by reading plural continuous codes from a code plate on which binary series codes are recorded, and inverting them logically. CONSTITUTION:A single track of a circular code plate 2 is divided into 12 equal segments, and five segments are made into shading parts (A), while the other segments are made into shading parts (B), the shading parts (A) is made 0, and the shading parts (B) are made 1, and they are composed to display 12 of binary circular series codes optically. The code plate 2 is rotated, the light is radiated from a light source 3, and five (K+1) detecting elements S1 to S5 are set to read continuous five codes. And the waveforms of corresponding output electric signals E1 to E5 are shaped in a circuit 5, and they are output as an absolute position data P1 of five bits which consists of codes D1 to D5. Furthermore, a logical inversion circuit 6 has inverters 11 to 15, and the logic values of the codes D1 to D5 are inverted respectively, so as to output the codes D6 to D10 of an absolute position data P2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute value encoder using a serial code represented by a binary code of 0 and 1 (herein referred to as a binary serial code).

[0002]

2. Description of the Related Art Conventionally, absolute value encoders have used a code plate for arranging a plurality of tracks having different slit numbers in a radial direction to form a binary code having a desired number of bits. There is a problem in that it is difficult to downsize the absolute value encoder because the number of tracks increases.

As one of the methods for solving this problem,
For example, there has been proposed an absolute encoder that uses a M-sequence random number code and is provided with a code plate in which a binary cyclic serial code is arranged in a single track. The M-sequence random number code is 2 ^K -1 (K is 2, 3,
.., which is a cyclic code pattern, it can be used as it is as a binary cyclic serial code for obtaining a required code plate. Also, M with 0 added to the M sequence code
The same applies to the case of using the L-series code.

[0004]

By the way, in the absolute value encoder as described above in which a code plate with a binary serial code is provided on a single track, one set corresponding to the number of divisions of the code plate required at that time is used. It is necessary to create the binary serial code of each time. Therefore, it is usually necessary to create a binary serial code in which a code having a predetermined number of overlapping bits does not appear by trial and error, which requires a great deal of labor and time. It was

Particularly, when two types of encoders that output different absolute position data with the same resolution are required, two types of binary serial codes having the same number of divisions are created and read from these codes. Since it is necessary to satisfy the requirement that all of the two absolute position data be different, there is a problem that further labor is required and the cost is significantly increased.

Therefore, an object of the present invention is an absolute value encoder which reads a plurality of continuous codes from a code plate having a binary serial code and outputs absolute position data indicating the absolute position of the read position. Therefore, it is to provide two types of absolute value encoders in which all the read absolute position data do not overlap.

[0007]

A feature of the present invention for solving the above-mentioned problems is that an absolute position indicating an absolute position is obtained by reading a plurality of continuous codes from a code plate provided with N binary serial codes. In the absolute encoder for outputting the position data, K + of consecutive binary serial codes attached to the code plate
1 (where K is an integer that satisfies 2 ^K-1 <N ≤ 2 ^K )
Is provided as absolute position data, and the absolute position data read by the detector all have different contents, and the logical inversion obtained by logically inverting the absolute position data and the binary serial code. The binary serial code is defined so that the binary serial code has different contents from the absolute position data read by the detector.
The point is that a binary serial code is provided on the code plate. The binary serial code is under the condition that “the absolute position data read by the detector have different contents and the sum of arbitrary two read binary values does not become 2 ^{K + 1} −1”. Or if the resolution is N = 2 ^K ,
It is also possible to prepare 2 ^K -1 M-sequence codes and add the code of "1" to the portion where K codes of "1" are continuous.

In addition, the absolute position data read by the above-mentioned detector all have different contents and the sum of two arbitrary read binary values is 2 ^{K + 1} −.
"1" is added to the binary serial code created under the condition that it does not become "1" or to the portion where 2 "1" codes of 2 ^K -1 M series codes are continuous. It can be created by obtaining the exclusive OR of the binary serial code created as above and the incremental code having the same number of divisions. The prepared binary serial code is provided on the code plate, and absolute position data read by K + 1 continuous (where K is an integer value satisfying 2 ^K-1 <N ≦ 2 ^K ) detectors is output. The absolute value encoder 1 and the second absolute value encoder which outputs the absolute position data obtained by reading the logically inverted binary serial code obtained by logically inverting the binary serial code by the logical inversion means by the detector.

[0009]

According to the feature of the present invention, K + 1 consecutive binary serial codes attached to the code plate are read by the detector as absolute position data, and N pieces of data indicating absolute positions are obtained. By inverting the absolute position data read by this detector by an appropriate logic inverting means, it is possible to obtain N pieces of absolute position data which are completely different from the N pieces of absolute position data. .

Further, the serial codes of the first code plate provided with the binary serial code and the second code plate provided with the logically inverted binary serial code are read by K + 1 consecutive detectors. Absolute position data that does not overlap can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing the configuration of a rotary type absolute value encoder 1 according to the present invention. The absolute value encoder 1 includes a code plate 2 fixed to a rotating shaft of an object to be detected (not shown), a light source 3 arranged on one side of the code plate 2, and an absolute position read by the code plate 2 to be described later. The detection elements S1 to S5 for optically reading the code of the code plate 2 by receiving light from the light source 3 through the slit representing the binary cyclic serial code formed as described above.
And a reading device 4 having.

As shown in FIG. 2, in this embodiment, the single track T of the code plate 2 is divided into 12 equal parts, and each divided segment has a white portion (light transmitting portion) of "1". The black part (light-shielding part) is optically set as “0” and is 12
Configured to display a number of binary cyclic serial codes. Further, since the present embodiment is a rotary type absolute value encoder, it is necessary to circulate the binary serial code.

In order to read 5 consecutive codes of the 12 binary cyclic serial codes optically applied to the code plate 2 as described above, the detecting elements S1 to S5, which are photodiodes, are tracked. They are arranged at intervals of 30 degrees along T.

Returning to FIG. 1, the detection elements S1 to S5 are
At that time, corresponding output electric signals E1 to E5 are output according to the state of the slits of the code plate 2 facing each other, that is, the light transmitting portion or the light shielding portion. The waveform is shaped and output as 5-bit first absolute position data P1 including codes D1 to D5.

The absolute value encoder 1 according to the present invention further comprises a logic inverting circuit 6 in order to obtain the second absolute position data P2 by logically inverting the logical value of each sign of the first absolute position data P1. ing. The logic inversion circuit 6 is
The first absolute position data P1 has inverters I1 to I5 for respectively inverting the logic values of the codes D1 to D5, and the codes D6 to D10, which are the logic inversion data of the codes D1 to D5, are logic inversion circuits. It is output from 6.

Next, the relationship between the number N of divisions of the code plate 2 and the number Q of detection elements required at that time will be described.

When the absolute position data read by K detectors are represented by K-bit binary values, the number of binary serial codes for obtaining absolute position data in which the binary values do not overlap is 2 ^K. It becomes the following. In the case of the absolute value encoder of the present invention, N (2 ^K-1 <N ≦ 2 ^K ) binary serial codes and an absolute position where a logically inverted binary serial code obtained by logically inverting the binary serial code is read by the detector. The number of all binary serial codes is 2N so that the binary values of the data do not all overlap.
(2 ^K <2 N ≤ 2 ^{K + 1} ), and the number Q of detection elements is K
+1 is required. Therefore, in this embodiment, as described above, = 1
Since it is an example of two divisions, 2 ^4-1 <12 ≦ 2 ^{4 and} K =
Therefore, the number Q of detection elements is from K + 1 to 5, so that the reading device 4 is provided with five detection elements S1 to S5.

On the other hand, the 12-division binary cyclic serial code attached to the code plate 2 states that "the absolute position data read by the five detectors all have different contents, and that any two reading 2 An example created under the condition that the sum of the decimal values does not become 2 ^{4 + 1} −1 ”is [110001011011] in the present embodiment.
A slit is formed on the single track T of the code plate 2 of the absolute value encoder 1 having a binary serial code with a white portion (translucent portion) being "1" and a black portion (light shielding portion) being "0" (see FIG. 2) ). In this binary cyclic serial code, the detection values are all different no matter which position five consecutive codes are detected, and the sum of the binary numbers of any two detection values does not become 2 ^{K + 1} -1. Has been defined. As a result, the twelve values obtained by reading the five consecutive codes of the binary cyclic serial code and the values obtained by logically inverting the twelve values are all different values.

In FIG. 3A, each detection position (address) 1
The values of the first absolute position data P1 at Nos. 12 to 12 are shown, and the values of the second absolute position data P2 at the respective detection positions (addresses) 1 to 12 are shown at (B) of FIG.
From FIG. 3, it is understood that two pieces of absolute value data having different contents are assigned to the same address, and the contents of the 24 kinds of absolute position data thus obtained do not overlap at all.

Here, the logical inversion serial code 001110100100 is obtained by logically inverting each bit of the binary cyclic serial code 110001011011 of 12 divisions shown in FIG. 2, which is also a binary cyclic serial code.

Moreover, when this logical inversion code is formed on the code plate in the same manner as shown in FIGS. 1 and 2 and the contents of continuous 5 bits are sequentially read out, 12 pieces thus read out are obtained. The absolute position data of 1 never overlaps with the absolute position data shown in FIG. In other words, this logical inversion code also has different detection values regardless of the position where five consecutive codes are detected, and the lower order K + 1 of the binary number indicating the sum of the binary numbers of arbitrary two detection values.
This is because the bit value does not become 2 ^{K + 1} -1.

[0023] Then 2 ^K pieces of binary circulation having similar properties code is created by adding the code "1" into K successive portions of "1" in the 2 ^K -1 pieces of M-sequence code The serial code is N =
An example of 16 divisions will be described. Regarding the M-series random number code and the method of creating the same, for example, pages 196 to 198 of Illustrated Communication Method-Theory and Actual Third Edition (published by Nobuo Araki Engineering Book Co., Ltd., March 15, 1987). It is explained on the page.

Since the M-sequence code is composed of K pieces of data in which 2 ^K -1 serial codes are consecutive, N pieces of data are used here.
= 16-1 (2 ⁴ -1), when an M-sequence code composed of four consecutive data is prepared, it becomes 111101011001000, and four "1" codes of this M-sequence code are consecutive. If a code of "1" is added to the portion, a binary cyclic serial code having the same property as the following N = 16 division is obtained. 1111101011001000

Here, the number of detecting elements Q becomes 5 by K + 1, and by the absolute value encoder 1 of the present invention shown in FIG. 1, by the five detecting elements S1 to S5 of the reading device 4 as in the case of the above 12 division. Absolute position data P1 and P detected
2 is shown in (A) and (B) of FIG. 4, and it can be seen that the contents of 32 kinds of absolute position data do not overlap at all.

Incidentally, by obtaining the exclusive OR of the binary cyclic serial code having such a property and the same number of incremental codes, another binary cyclic serial code having such a property is obtained. You can

This will be described with reference to FIGS. 5 and 6 by using the N = 16 division binary cyclic serial code described above. In FIG. 5, A is a binary code based on a basic serial code and B is an incremental binary code, and the exclusive OR obtained based on the codes A and B is Y.
Then, there are four kinds of combinations between A, B, and Y.

There are two ways of arranging the incremental code, that is, "0" start and "1" start. First, the "0" start will be described. However, the number of codes in this case is 16.

The 16 (divided) binary cyclic serial codes are FA
[1111101011001000], and this serial code FA and the incremental code F for the start of “0”
When the exclusive OR with B is obtained with reference to FIG. 5, a serial code FC of [1010111110011101] is obtained as shown in FIG.

7A and 7B, absolute value data P3 when five consecutive codes of the code string FC shown in FIG. 6 are read and each code of the read absolute value data. The absolute value data P4 obtained by logically reversing is shown. From FIG. 7, it can be seen that the 32 pieces of absolute position data thus read do not overlap each other at all.

In the above example, the incremental code is "0".
Although the case of start is taken as an example, the exclusive OR in the case of "1" start is as follows. 16-bit serial code 1111101011001000 Incremental code 1010101010101010 Serial code by exclusive OR 0101000001100010

The binary serial code [0
101000001100010] is the same as the code string obtained by logically inverting the code string obtained by using the above-described "0" -start incremental code. Therefore, the same result can be obtained regardless of which of the two types of incremental codes is used.

In the above embodiment, the optical rotary encoder having a circular code plate has been described as an example. However, in a linear encoder having a linear code plate, or a magnetic encoder for detecting a code in a timely manner. Of course, the present invention can be applied in the same manner.

[0034]

As described above, according to the present invention, an absolute value encoder for reading a code of a plurality of consecutive bits from a code plate provided with a binary cyclic serial code and outputting absolute position data indicating an absolute position. Therefore, two different absolute position data can be obtained at each detected position, and an absolute value encoder that prevents all read absolute position data from overlapping can be easily configured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an absolute value encoder according to the present invention.

FIG. 2 is an explanatory diagram for explaining a positional relationship between a code plate and a detection element of the absolute value encoder shown in FIG.

FIG. 3 is a diagram showing 24 kinds of absolute position data read from an absolute value encoder based on the code plate shown in FIG. 2;

FIG. 4 is a diagram showing 32 types of absolute position data read from a 16-division absolute value encoder according to the present invention.

FIG. 5 is a diagram showing an example of an exclusive OR element and its input / output relationship.

FIG. 6 is a diagram showing two parts to be provided on each track of the code plate shown in FIG.
Explanatory drawing for demonstrating the preparation procedure of two binary cyclic serial codes.

7 is a diagram showing the contents of 32 kinds of absolute position data obtained when the binary cyclic serial code created by the procedure shown in FIG. 6 is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absolute value encoder 2 Code plate 3 Light source 4 Reader 6 Logic inversion circuit S1 to S5 Detection element T Track

Claims (1)

[Claims] 1. An absolute value encoder which reads a plurality of consecutive codes from a code plate having N binary serial codes and outputs absolute position data indicating an absolute position, wherein the absolute value encoder is provided to the code plate. A detector for reading consecutive K + 1 binary serial codes (where K is an integer value satisfying 2 ^K-1 <N ≦ 2 ^K ) as absolute position data is provided, and the binary serial code is used for the detection. The absolute position data read by the detector have different contents, and the logically inverted binary serial code obtained by logically inverting the absolute position data and the binary serial code is the absolute value read by the detector. An absolute encoder characterized in that it is defined so that the contents are all different from the position data.