JPH03248062A - Detecting method for rotating direction - Google Patents

Abstract

PURPOSE:To detect the rotating direction correctly and easily by a method wherein binary data is stored in a memory means every time it is changed, and the rotating direction of a rotary encoder is determined with reference to a table based on the stored binary data. CONSTITUTION:An output of a rotary encoder 12, i.e., two signals from a photodetecting element 4 are given respectively to hysteresis comparators 14 and 16, and input to a microcomputer 18 as binary data comprised of bit 0 and bit 1. The binary data is stored in a RAM. Meanwhile, a program to determine the direction and also the pattern of the change of the binary data for each of the forward and backward directions are stored beforehand as a table in a ROM of the microcomputer 18. Whenever the binary data is changed, the previously-written data and the currently-written data are compared with the data in the ROM table, so that the rotating direction is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting a rotational direction, and particularly to a method for detecting a rotational direction of a rotating device such as a motor of a tape running device. The present invention relates to a rotation direction detection method for determining the rotation direction of a rotary encoder that outputs two signals having the following characteristics.

[Prior art]

Generally, in a rotary encoder, as shown in FIG. 5, a slit 2 is formed in a disk 1 that is moved as it rotates, and a light emitting element 3, a light receiving element 4a, and 4b is provided. The light-receiving elements 4a and 4b each touch the light-emitting element 3 at a position separated by a predetermined distance related to the size of the slit 2.
is arranged to receive light output from the

The light-receiving elements 4a and 4b output rectangular A-phase signals and B-phase signals (pulses) as shown in FIG. 6A or 6B, respectively, and these A-phase signals and B-phase signals are at 90 degrees to each other. It has a phase difference of

Conventionally, when detecting the rotation direction based on the A-phase signal and the B-phase signal from such a rotary encoder, for example, the B of the rising edge of the human phase signal is detected.
The level of the phase signal was detected and used to determine whether the direction of rotation was forward or backward.

On the other hand, as a counter circuit for counting such A-phase signals and B-phase signals, a counter circuit as shown in FIG. 7 is known. In this counter circuit, for example, integrated circuits "MC14510" manufactured by Motorola are connected in series, and each circuit is configured to receive an A-phase signal and a B-phase signal.

Then, for each digit or place from each integrated circuit, BC
D data is output.

The counter circuit shown in FIG. 7 has the advantage that by counting rising edges and falling edges, it is possible to obtain twice the count value as compared to counting only rising edges.

[Problem to be solved by the invention]

However, in a simple circuit as shown in FIG.
The direction of rotation cannot be determined based on the phase signal and the B-phase signal.

Therefore, the main object of the present invention is to provide a method for detecting the direction of rotation, which counts rising edges and falling edges and can easily determine the direction of rotation.

[Means to solve the problem]

Briefly speaking, the present invention provides a method for detecting the rotational direction of a rotary encoder that outputs double codes having a phase difference of 90 degrees from each other. In this rotational direction detection method, the rotational direction of the rotary encoder is determined by referring to a table based on the binary data stored in the storage means.

[Effect]

Two rectangular wave signals having a phase difference of 90 degrees from each other from the rotary encoder are each binarized by, for example, a hysteresis comparator, and the binarized data is stored in, for example, a microcomputer's RAM (Random
Access Memory).

On the other hand, microcomputer ROM (Read O
nlyMemory), a program for determining the direction and change patterns of the binarized data for each forward direction and reverse direction are stored in advance as a table. Then, each time the binarized data changes, the rotation direction is determined by comparing, for example, the previously captured data and the currently captured data with the data in the ROM table.

〔Effect of the invention〕

According to the present invention, even if a counter circuit such as that shown in FIG. 7 that counts both rising edges and falling edges is used, the direction of rotation can be accurately and easily detected.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

〔Example〕

FIG. 2 is a block diagram showing an embodiment of the present invention.

In the revolution counting device 10 of this embodiment, a rotary encoder 12 similar to the conventional one is used. That is, the rotary encoder 12 includes a disk 1 connected to a rotating part (not shown), a slit 2 similar to that shown in FIG. Place.

The output of the rotary encoder 12, that is, the A-phase signal and the B-phase signal (pulse) from the light receiving element 4 are given to hysteresis comparators 14 and 16, respectively.
It is input to the microcomputer as binary data such as ito and bitl.

In the microcomputer 18, the data bito and bitl inputted from the hysteresis comparators 14 and 16 are stored in memory A and/or memory B formed in an appropriate area of RAM, for example, and are stored with reference to a ROM table prepared in advance. Rotary encoder 12
Detect the direction of rotation. This detection output is then given as a count control signal to an up/down counter 20 having the same circuit configuration as, for example, FIG. 7.

On the other hand, this up/down counter 20 is provided with data bito and bitl (designated as bOlbl in the drawing) from hysteresis comparators 14 and 16, either through the microcomputer 18 or directly.

Referring to FIG. 1, microcomputer 18 receives data bito and bitl in step S1, and stores the data bitl and bitl in memory A in subsequent step S2.

Then, in step S3, further data bitl
and bito are input, the data bitl or bit_t is input in step S4.

determine whether the has changed. any data bi
When a change in tO or bill is detected, step S
5, the data bit1 and bito at that time
is stored in memory B, which is also formed in the microcomputer 18. In this way, step 5L-3
In step 5, the microcomputer 18 stores the change in the memory B each time a change occurs in the binary data bitO and/or bitl.

Note that a pattern table as shown in the following table is set in the microcomputer 18.

(Hereinafter, blank spaces) In the pattern table shown in 2, appearance patterns of binary data bitl and bitO are stored in each direction (UP/DOWN) at addresses no. to 4 of the ROM. That is, as shown in FIGS. 3 and 4, in the forward rotation (UP) direction, the binarized data is
Changes in the order of 10 → 11 → 01 → 00 → 10...
In the reverse (DOWN) direction, 00→01→11→
It should change in the order of lO→00...

To be more specific, when rotating in the positive direction, the rotary encoder 12 outputs signals in FIGS. 3(A) and 3(B).
) outputs an A-phase signal and a B-phase signal that change as shown in FIG. And these are the hysteresis comparator 14
and 16 (Figure 2), and Figure 3 (C
) and the data bitO and bi shown in FIG. 3(D)
It is input to the microcomputer 18 as tl. Note that since the up/down counter 20 is as shown in FIG. 7, as shown in FIG. 3(E), the up/down counter 20 is It will be given to you. Between these count pulses, the bit pattern of the binary data changes as shown in FIG. 3(F).

The same can be said of the case where the rotary encoder 12 is rotating in the opposite direction.
) are output, and the A-phase signal and B-phase signal shown in FIG.
Binarized data btto and bitl shown in FIG. 4(C) and FIG. 4(D) are obtained. Therefore, between the count pulses shown in FIG. 4(E), the bit pattern changes as shown in FIG. 4(F).

Therefore, such change patterns are stored in this pattern table.

Then, in step S6, the microcomputer 18 uses the R in the UP direction based on the data in the memory A.
Find the address n of OM and set it as variable U. For example, when "10" is stored in memory A, address n becomes "0" and variable U also becomes "0".

Further, in step S7, an address n in the DOWN direction is determined based on the data in the same memory A, and this is set as a variable V. In the previous example, the address n becomes "2" and therefore the variable V also becomes "2" in step S8.
Then, the variable U obtained in the previous step S6 is incremented by "rl", and in step S9 it is determined whether or not u=4. If so, the variable U is set to "0" in step SIO. In steps 31 to 313, the variable V is processed similarly to steps S8 to S10. In this way, in steps S8 to S10 and Sll-S13, the variables U and V are changed in a so-called ring counter manner.

In step S14, the binarized data bi corresponding to the variable U incremented in the previous step S8 is
Find the pattern of ll and bitO. Then, in step S15, it is determined whether the obtained pattern is the same as the data stored in memory B in step S5. For example, “1” is stored in memory A.
0" is stored and "11" is stored in memory B, the variable U in step S6 is "0".
, and the variable U in step S8 is "1". Therefore, the pattern found in step S14 is 1
1". On the other hand, since "11" is stored in memory B, in this step 315, "YES" is stored.
”, and therefore microcomputer 1
In step B, an UP detection signal is output in step S16.

Further, when it is determined in step S15 that "NO", the microcomputer 18 performs step S17.
In step 311, the pattern of the corresponding binary data bit1 and bito of the incremented variable V is obtained, and in step 318, it is determined whether the pattern is the same as the pattern stored in the memory A. For example, when "10" is stored in memory A, the variable V in step S7 becomes "2", and when it is incremented in step Sll, it becomes "3". On the other hand, data “00” is stored in memory B.
If it is stored, the pattern read out in step S17 will be the same as that, and in step 318 it will be determined as "YES". As a result, step S1
At 9, the microcomputer 18 outputs a DOWN detection signal.

Note that after step 316 or S19, step S
At step S20, the microcomputer 18 outputs a count pulse and supplies it to the up/down counter 20, and at step S21, the contents of memory B are transferred to memory A and the next pulse input is awaited.

Further, if "NO" is determined in both steps S15 and 318, there is no corresponding pattern, and therefore, in step 322, the microcomputer 18 performs error processing.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing a rotation count circuit for realizing the embodiment of FIG. 1. FIGS. 3 and 4 are timing diagrams showing waveforms and data of various parts in the forward direction and reverse direction, respectively. FIG. 5 is an illustrative diagram showing a rotary encoder. FIGS. 6A and 6B are timing diagrams showing the A-phase signal and B-phase signal output from the rotary encoder. FIG. 7 is a block diagram showing an up/down counter circuit. In the figure, 10 is a rotation count circuit, 12 is a rotary encoder, 14.16 is a hysteresis comparator,
18 is a microcomputer, and 20 is an up/down counter.

Claims (1)

[Scope of Claims] A method for detecting the rotational direction of a rotary encoder that outputs two signals having a phase difference of 90 degrees from each other, comprising: storing the binary data in the storage means every time the binary data changes; A rotation direction detection method, wherein the rotation direction of the rotary encoder is determined by referring to a table based on the binarized data stored in a storage means.