JPH0222511A - Rotary encoder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a rotary encoder that optically detects a rotation angle.

(bl Conventional Technology) Conventionally, a rotary encoder has been used as a device to detect the rotation angle of a rotor, which is an object to be measured.A conventional general rotary encoder uses a rotating disk on which an optical pattern is formed. An optical sensor that reads an optical pattern is placed near this rotating disk.When detecting the rotation angle of the rotor, which is the object to be measured, as an absolute quantity, the optical pattern of the rotating disk is A digital code representing or corresponding to the absolute angle is patterned.

(C) Problems to be Solved by the Invention However, in conventional rotary encoders that detect the absolute angle of a rotating disk, a code pattern made of an opaque material is formed on a transparent plate made of glass, transparent resin, etc. The code is configured to be read by detecting the presence or absence of transmitted light. As a result, light may be refracted and scattered by a transparent material such as a glass plate or a transparent resin plate, and reading errors may occur. Further, there was also the problem that the pattern forming process was complicated and the manufacturing cost was high.

Therefore, it has been considered to form a code pattern by forming slits in an opaque material such as a metal plate, but this has the following problems.

Figure 8 shows the relationship between each angle and its code. As shown in the diagram, for angles (0 to 359 degrees), the 100's place is 2 bits, the tens' place is 4 bits, and the 1's place is 4 bits. It is expressed in BCD code. If we consider the case where a slit is formed at bit l, for example, 100@~
For 199@, the 2° bits in the 100th place are 1 consecutively.
That is, slits are formed, and from 200° to 299@, slits are formed at the 2' bits of the 100's, and from 300° to 359'', continuous slits are formed at all 2 bits of the 100's. Since continuous slits are formed in the circumferential direction in this manner, the inner circumferential side and the outer circumferential side of the rotating disk are physically separated with the slit as a boundary.

An object of the present invention is to provide a rotary encoder in which a code representing an absolute angle can be patterned depending on the presence or absence of slits, and which can be used with the portions without slits connected to each other.

(Means for Solving Problem d1) The present invention provides a rotary encoder comprising: a code plate in which a code representing the absolute angle of the rotary disk is formed as an optical pattern; and an optical sensor for reading the code; A non-transparent plate having a code formed by slits is used as a code, and the code at a specific angle is coded in a different way from the code at other angles so that the slits form a pattern that does not continue beyond a certain angle in the angular direction. The present invention is characterized in that it includes angle data generation means for generating angle data from the output data of the optical sensor.

(e) Function In the rotary encoder of the present invention, a code representing an absolute angle is formed on the rotating disk using a slit. The angular cord prevents angular continuity of the slit.

FIG. 1 shows an example of a code on a code plate used in a rotary encoder to which the present invention is applied. This example corresponds to the example shown in FIG. 8, in which the angle where the 1's digit is 0 is defined as a specific angle, and is coded in a different way from other angles.

The flag in the figure is a bit that distinguishes between two types of encoding methods. Furthermore, the 100's place is represented by 3 bits, the tens' place by 4 bits, and the 1's place by 4 bits. Codes for specific angles are converted by bit shifting in a specific range and complementation of specific bits. As is clear from comparison with the example shown in FIG. 8, the slits in the 100th place are separated every 10 degrees. The angle data generating means according to the present invention generates angle data from the output data of the optical sensor that reads these codes.
In the example shown in the figure, angle data is obtained in the same manner as codes for other angles by performing the inverse conversion of the code conversion described above for the code whose flag focus is 1.

(f) Embodiment FIG. 2 is a code plate used in a rotary encoder according to an embodiment of the present invention, FIG. 3 is a diagram showing a part of the code pattern formed on the code plate, and FIG. 4 is an angle diagram. It is a figure showing the relationship between and a code.

The area indicated by A in FIG. 2 is a forming area of oblique slits consisting of linear slits inclined with respect to the radial direction of the code plate, and is used to obtain a resolution of less than 1 degree. Further, the area indicated by B is a slit forming area of a digital code that represents an absolute angle with a resolution of 1 degree. Note that the numbers θ to 35 in the figure indicate the 10th digit of the angle for reference.

FIG. 3 shows the code shown in FIG. 2 expanded into a straight line. As shown in the figure, the digital code is represented by 12 bits, with the most significant bit as a flag bit, the 100's digit is coded with 3 bits, the O's digit is coded with 4 bits, and the 1's digit is coded with 4 bits. The hatched portion in the figure corresponds to bit 1 and has a slit formed therein. For example, when the optical sensor is at position Pi (356 degrees), 00
When 1101010110 is read and the optical sensor is at position P2 (350 degrees), 10000000
0101 is read. The oblique slit formed in area A is inclined with respect to the optical sensor over a width of 1 degree. Therefore, depending on the light receiving position of the optical sensor in area A, the relative angle can be detected with a resolution of less than 1 degree.

As shown in Figure 4, write the 12 pin code from X0 to X+O.
In other words, when the flag X I I is O, the angle is encoded as a BCD code as shown in the figure. X
When 11 is 1, X0 to X+O are coded as follows. For example, if the angle is 350 degrees as shown in parentheses in Figure 4, the BCD code is 011010.
10000, but X.

and the complement of X8, X. and X, and X4~missing is shifted to X0~X. By performing such encoding every 10 degrees, the first
As shown in the figure, the slits do not continue beyond a certain angle in the angular direction. Fig. 5 is a block diagram of the control unit that calculates the absolute angle using the code plate configured as described above, and Fig. 6 is a flowchart showing the processing procedure. In FIG. 5, reference numeral 1 indicates a 1024-dot CCD line sensor, and reference numeral 2 indicates a read controller that controls the light reception accumulation time and readout shift control. The waveform shaping circuit 3 shapes the waveform of the read serial video signal. The CPU 5 outputs a read instruction signal to the read controller 2 via the I10 interface 4, and also stores the output signal of the waveform shaping circuit 3 in a predetermined area of the RAM 7. A program to be executed by the CPU 5 is written in the ROM 6 in advance.

The CPU 5 executes the procedure shown in FIG. 80~ here
Bl+ is a buffer that creates a BCD code that represents an angle with a resolution of one displacement position, and X0 to X11 are buffers that create and store a 12-bit code from the waveform-shaped reading controller output signal.A0 to A are code board buffers. A%J
This is a 4-bit buffer that obtains angle data from data in the J region with a resolution of less than 1 degree. Using these buffers, angle data is obtained in the following steps. First, buffer B. ~ Clear BII (nl). Thereafter, a read instruction signal is output to the read controller 2, and the obtained data for one line is read (n2). Out of the read data, write the 12-bit code from the data in area B from X0 to
Create in X11 (n3).

Next, determine the state of flag bit Xll (n4)
, if the flag bit is O, move the lower 10 bits of buffer X to the lower 10 bits of buffer B (n5). As a result, a BCD code of one displacement position is obtained in buffer B. After that, A of the data read in n2? , ] 4-bit angle data with a resolution of less than 1 degree is obtained from the data in the buffer A (n8). Specifically, bit 1 of several 100 bits (dots) of data in the A9i area.
This is done by encoding the position in 4 bits.

If the flag bit is 1 in the determination of n4, Xlo+X
9 and move them to Bl and Bl (n6). Next, move X0 to X3 directly to B4 to B7 (nl)
. Thereafter, as in the case where the flag bit is 0, 4-bit data less than one degree from the A area data is created in A0 to A (n8).

Although the above-mentioned embodiment is an example in which the output signal from the CCD line sensor is once read into the memory and then processed by the microprocessor, it is also possible to perform these processes by random logic. FIG. 7 shows an example of such a case. In FIG. 7, the read controller 2 reads the output signal of the CCD line sensor 1, and the signal waveform-shaped by the waveform shaping circuit 3 is serially input to the buffer X12 at a predetermined timing. The code conversion circuit 13 performs code conversion when the 12-bit data in the B area of one line of data is input to the buffer 12, and writes 12-bit angle data of one displacement into the register B. The logic circuit of the code conversion circuit 13 is as follows.

Bo=X hundred・Xo B+ =X++-Xt Bt=X++-Xz B3　　　Xll・　X3 Ba -Xll -Xa +X++ -X.

Bs ”Xll・X＠ +
, +Xll-X3B,. ==0 The counter 16 is a circuit that performs a counting operation based on the signal output from the timing signal generation circuit 11, and when the A area timing signal is generated from the timing signal generation circuit 11 and is black, it releases the reset and counts the clock signal. do. Rough latch. Therefore, the latch circuit 15 latches a value corresponding to the opening position of the diagonal slit in the A area among the output signals of the CCD line sensor.

With the above configuration, angle data with a resolution of 1 degree is obtained in the register B, and angle data with a resolution of less than 1 degree is obtained in the latch circuit 15.

(Effects of the Invention As described above, according to the present invention, the cords form a pattern that does not continue beyond a certain angle in the angular direction, so even if a non-transparent plate with slit cords formed thereon is used as the code plate, the code plate does not have slits. not be separated by
Therefore, compared to the case where a transparent material such as a glass plate or a transparent resin plate is used as the code plate, there is no refraction or scattering of light, and the reading accuracy of the code pattern can be improved. Further, it becomes possible to easily form a code pattern.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of coding on a code plate according to the present invention, Fig. 2 is a plan view of a code plate used in a rotary encoder according to an embodiment of the present invention, and Fig. 3 is a part of the code plate. This is a developed diagram. FIG. 4 is a diagram showing an example of codes formed on the code disk and their encoding. Fifth
The figure is a block diagram of the control section of the rotary encoder.
The figure is a flowchart showing the processing procedure. FIG. 7 is a block diagram of a control section of a rotary encoder according to another embodiment. FIG. 8 is a diagram showing an example of coding on a code plate used in a conventional rotary encoder.

Claims (1)

[Claims] (1) In a rotary encoder consisting of a code plate in which a code representing the absolute angle is formed as an optical pattern on a rotating disk, and an optical sensor for reading the code, the code plate is a non-transparent plate in which a code formed by a slit is formed. , the code for a specific angle is coded in a different way from the code for other angles so that the slits are in a pattern that does not continue beyond a certain angle in the angular direction, and angular data is generated from the output data of the optical sensor. A rotary encoder characterized in that it is provided with angle data generation means.