JPH04147011A - Device and method for detecting absolute position - Google Patents

Abstract

PURPOSE:To enable detection of an absolute position by an inexpensive constitution, by synthesizing binary codes of a plurality of absolute code trains detected serially and by converting them into a binary code train for which the number of recording bits of position data is parallel. CONSTITUTION:On the opposite sides of a code plate 1, light-emitting elements 4a and 5a and light-sensing elements 6b and 7b are arranged oppositely to an incremental code train 2, and light-emitting elements 6a and 7a and light- sensing elements 6b and 7b are arranged oppositely to an absolute code train 3. The elements 4a and 4b, and 5a and 5b, facing each other detect a slit array in a state wherein they are different in a phase by 90 deg. from each other, and incremental signals of phases A and B are obtained. In a signal generating means 11, an absolute signal and the incremental signals of phases A and B are generated from detection signals obtained from the elements 4b to 7b. In a signal conversion means 12, serial absolute signals are converted into position data 13 of parallel bit arrangement on the basis of the incremental signals, and the position data of binary data are converted 14 into position data in a prescribed form.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an absolute code type absolute position detection device and absolute position detection method.

Conventional technology Conventionally, magnetic and optical encoders have been widely used to detect rotational position etc. absolutely, and optical encoders that use double encoded codes have particularly good responsiveness and high reliability. It is possible to detect the absolute position.

Problem to be Solved by the Invention However, with the dual encoding code, only one bit of position data can be obtained with one code string, so in order to obtain a high-resolution encoder, codes for the required number of bits are required. This requires columns, corresponding light-emitting elements, light-receiving elements, and amplifier units, which increases the number of parts and requires time and effort for adjustment, resulting in high costs.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide an absolute position detecting device and an absolute position detecting method that can detect an absolute position with an inexpensive configuration with a small number of parts.

Means for Solving the Problems In order to achieve the above object, the present invention uses an absolute code string in which position data is recorded in binary code along the direction of movement, and is regularly coated in correspondence with each binary code. A code board provided with an incremental code string recorded with and means for converting into a parallel binary code string representing the data.

Effect of the Invention With the above configuration, the present invention obtains multi-bit position data and performs absolute code position detection by simply providing two code strings, an absolute code string and an incremental code string, on the code plate.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 7.

To simplify the explanation, this embodiment will be described in the case of 4-bit absolute code position detection and the case where there are two absolute code detection means. FIG. 1 is a partial sectional view of the absolute position detection device according to the present invention. In the figure, 1 is a code plate that can rotate integrally with the central shaft 20, and on its outer periphery there are two rows of slits in the circumferential direction. code string 2
, 3 are formed. As shown in FIG. 2, the cord row 2 on the outer circumferential side is an incremental cord row, and is formed by a slit row regularly formed at a predetermined pitch. The code row 3 on the inner circumferential side is an absolute code row, and is composed of a binary code depending on whether or not there is a slit opening corresponding to each pitch of the incremental code row 2. Position data is stored in this binary code. is recorded in Jinoal.

Returning to Figure 1, on both sides of the code board 1,
A light emitting element 4a facing the incremental code row 2,
5a and light receiving elements 4b, 5b are arranged, and light emitting elements 6a, 7a and light receiving elements 6 are arranged opposite to the absolute code row 3.
b and 7b are respectively provided. A pair of light-emitting elements 4a and a light-receiving element 4b facing each other and another pair of light-emitting elements 5a and light-receiving elements 5b detect the slit row with a phase difference of 90'' from each other, and the incremental signals of the A phase and B phase are detected. It is arranged so that it can be obtained.

Also, a pair of light emitting elements 6a and light receiving elements 6 facing each other
b, and the other pair of light emitting element 7a and light receiving element 7b are arranged at positions shifted by 2 bits in the absolute code string, and 2
Absolute codes with bits shifted are now detected. Furthermore, the code plate 1 and the light receiving elements 4b, 5b,
Between 6b and 7b is an opening 9a corresponding to each of these light receiving elements.

A fixed mask 8 having 9b, 10a and 10b formed thereon is provided.

Position data is recorded in the absolute coat row 3 in FIG. 2 using M-sequence codes. According to the absolute code sequence 3 using this M-sequence code, each time new position data is read one by one, that bit code and a predetermined number of bit codes that have been sequentially read before are used to generate absolute position data. It can be read. To explain this in the case of 4-bit position data with reference to FIG. 3, if an M-sequence code of ``roooo 1 QC) 110101111'' is serially recorded in absolute code string 3, for example, from the starting point 31 in the figure in the direction of the arrow r0000 when reading the first 4 bits into
The position data 13 of = is obtained, and thereafter, '0OOIJ' is sequentially read every time one hit is read.

“0OIOJ,” “0100J,’1001”.

"0OIIJ, [0110J, "ll0IJ.

'l0IOJ,'0IOIJ,'l0IIJ.

"0111", "1111", "1110".

Position data 13 of "l100J" and "100OJ", all of which have different bit arrangements, is obtained, and with this, the position can be detected absolutely.

FIG. 4 shows a signal processing circuit for obtaining position data in this manner and detecting the absolute position. Light receiving element 4
Signal generation means 11 generates an absolute signal and incremental signals of A phase and B phase from the detection signals obtained from the detection signals obtained from the sensors b, 5b, 6b, and 7b, and converts the serial absolute signal into parallel position data 13 based on the incremental signal. It is composed of a signal converting means 12 for converting the data, and a position data converting means 14 for converting position data in binary data into position data in a predetermined format.

FIG. 5 shows FIG. 4 in more detail. The detection signals obtained from the light receiving elements 4b, 5b, 6b, and 7b are input to the absolute incremental signal generation means 11. The absolute incremental signal generating means 11 is composed of a general amplifier circuit and a waveform shaping circuit, and each circuit is provided corresponding to each of the light receiving elements 4b, 5b, 6b, and 7b. Regarding the absolute signal output from the amplification and waveform shaping circuit, the signal from the light receiving element 6b is input to the shift register 16a, and the signal from the light receiving element 7b is input to the shift register 16b. The absolute signal is input to the shift registers 16a and 16b at the rising edge of the A-phase incremental signal. A timing chart showing the timing is shown in FIG. In FIG. 6, the light receiving element 6
The signal from the light receiving element 7b is an absolute signal A, and the signal from the light receiving element 7b is an absolute signal B. Further, the signal from the light receiving element 4b is an A-phase signal, and the signal from the light receiving element 5b
The signal from is the B-phase signal.

Now, if absolute position detection is started from timing a, at the first rise of the A-phase signal, O is input to the 2-bit shift register 16a, and O is input to the shift register 16b. Furthermore, the code plate 1 rotates, and at the rising edge of the next A-phase signal, the shift register 16 that was entered first
T-digits a and 16b are shifted by 1 bit and new data is input. Therefore, the 2-bit shift register 1
6a is inputted with 0 and becomes "00", and shift register 16b is input with 1 and becomes "01". Then, the data in the shift register 16a is combined as the upper 2 bits and the data in the shift register 16b as the lower 2 bits, and '00
01 J, the parallel position data 13 is output, and becomes the output of the serial-parallel signal converting means 12. In the ROM 18 constituting the position data conversion means 14, binary data as shown in FIG. 7 is written with the position data 13 as an address.
The base position data is output and the up/down counter 1
Grise 1 in the top 4 bits of 9. will be played. The lower two bits of the up/down counter 19 are preset to "OO". After the up/down counter 19 is preset with 6-bit data, it is counted up or down by a clock signal or a clock signal which is obtained by multiplying the incremental signal by 4. Whether to count up or count down is determined by the rotation direction signal created from the A-phase and B-phase signals. The output of the up/down counter 19 becomes absolute position data.

In the above embodiment, an M-sequence 4-bit code is used as the absolute code string, but it goes without saying that the same will apply even if the number of bits increases. Further, although the case where there are two absolute code detection means has been described, even in the case where there are three or more absolute code detection means, data of the required number of bits can be detected by synthesizing the data of the shift register in the same manner.

Next, an embodiment of position detection using the absolute position detection device of the present invention will be described with reference to FIGS. 8 and 9. In the absolute position detection device of the present invention, in order to detect the absolute position, since the absolute code is detected serially, it is necessary to move by the number of recording bits. For example, in order to detect a 12-bit absolute position, 12 bits must be moved in a fixed direction. When used as a position detection device for an industrial robot, etc., the robot detects the absolute position and aligns the origin when the power is turned on, but there is a desire to minimize the movement at that time.

This embodiment aims to reduce the distance from the position where absolute position detection starts to the position at which absolute position detection is completed.The timing chart in Fig. 8 and the diagram of the code plate in Fig. 9 are shown below. I will explain using

When the absolute position l is detected from the position a in FIG. 9, that is, from the time point a in the timing chart of FIG. . At this time, since the absolute position is not yet known, a 4-fold signal is created from the incremental signals of the A and B phases, the amount of movement is measured with an up/down counter, and the position is determined by 8 force counts, that is, the position moved by 2 bits in the absolute code string. That is, it is at position b in FIG. 9, and at time b in the timing chart of FIG. 8, at which point it is reversed, rotated in the CW force direction, and starts detecting the absolute position as in the conventional example.

In the above embodiment, the amount of rotation in the CW force direction and the amount of rotation in the CCW direction are set to be the same, but depending on the actual situation, the amount of rotation in the CW force direction may be greater and the amount of rotation in the CCW direction may be less, or vice versa. It doesn't matter.

According to the above absolute position detection method, as is clear from the above explanation, an absolute code string in which position data is serially recorded along the movement direction using a binary code is serially recorded based on a detection signal of an incremental code string. The position detecting device detects the position at which absolute position detection starts by moving by the number of bits within the number of recording bits of position data, then inverting, and then moving by the number of recording bits to serially detect an absolute code string. It is possible to reduce the distance from the point to the position where the absolute position has been detected.

Effects of the Invention As is clear from the above description, the absolute position detection device of the present invention synthesizes binary codes of a plurality of serially detected absolute code strings, and generates a parallel binary code corresponding to the number of recording bits of position data. - Since the absolute position can be detected by converting it into a code string, the absolute position of multi-bit position data can be detected simply by providing at least two code strings, an absolute code string and an incremental code string, on the code plate. It has the effect of

[Brief explanation of drawings]

1 to 6 are views showing one embodiment of the present invention, in which FIG. 1 is a partial side sectional view of the absolute position detecting device of the present invention, FIG. 2 is a plan view of a code plate, and FIG. 3 is a diagram showing an embodiment of the present invention. Explanatory diagram of M-series code, 4th
Figure 5 is a block diagram showing the schematic configuration of the signal processing circuit, Figure 5 is a block diagram of the signal processing circuit, Figure 6 is a timing diagram of the operation of the serial-parallel conversion means, and Figure 7 is data stored in the ROM. FIGS. 8 and 9 are explanatory diagrams of the operation of an embodiment in which position detection is performed using the position detection device of the present invention. 1... Code plate, 2... Incremental coat row, 3... Absolute code row, 4b, 5b... Incremental signal detection element (detecting means) , 6b, 7b... Absolute signal detection element (detecting means), 12...
・Serial-to-parallel signal conversion means (means for synthesizing binary codes of multiple absolute code strings detected serially), 18...ROM (parallel binary code string of the number of recording bits of position data) ). Agent's name: Patent Attorney Yoshiaki Ogata 2 people 1-11 Court 2-- Incremental column 3--m1 Awo'Socie top code rows 6b, 7b--
-Araso 9 Knee upper signal l child (decision, self + 艮) 1---Ko' F section 2---I> 2 Shimej Ruko 1 γ column 3---Abun Soyu) Hooda] 4b, 5b-1-a 2-lmental stem δ (detection t, b-!F setting) Fig. 7 j Fig. 9

Claims (2)

[Claims] (1) A code plate provided with an absolute code string in which position data is serially recorded along the movement direction using a binary code, and an incremental code string in which codes are regularly recorded corresponding to each binary code, and the incremental code. means for detecting a plurality of absolute code strings, a plurality of detection means for detecting the absolute code strings, a means for synthesizing binary codes of a plurality of serially detected absolute code strings based on detection signals of the incremental code strings; An absolute position detection device comprising means for converting a code into a parallel binary code string of the number of recording bits of position data. (2) Using the absolute position detecting device according to claim 1, after moving within the number of bits within the number of recording bits of position data, reverse and move by the number of recording bits to detect an absolute code string. An absolute position detection method characterized by: