JPS61215909A - Position detecting device - Google Patents

Abstract

PURPOSE:To detect the position of the high resolution with a low cost by using two rectangular wave signals outputted from a pulse encoder. CONSTITUTION:Each time the prescribed angle rotation is executed for a driving shaft 2, a pulse encoder 1 mutually generates two pulse signals PA and PB where the phase is dislocated to 90 deg., and is inputted to an up-and-down pulse generating circuit 10 and a decoder 11. Next, the circuit 10 synchronizes to the rise of a signal PA and generates an up counting pulse signal PU and a down counting pulse signal PD. The up-and-down counter 12, when signals PU and PD are impressed, respectively counts up or counts down, and the counting data of (n) bit are outputted as the higher order (n) digit of the position detecting signal of n+2 bit, namely, as bit D2-Dn+1. On the other hand, the decoder 11 outputs a binary signal showing the four different levels from the assembly of the signals PA and PB as the signal of the lower order two digits of the position detecting signal, namely, as bits D0 and D1. Thus, the position detecting signal of n+2 digit having the resolution four times as much as the encoder 1 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a position detection device using a pulse encoder.

(B) Prior Art This type of position detection device is equipped with a pulse encoder that generates two types of rectangular wave signals whose 901 phase leads and lags depending on the moving direction of the object. By inputting a rectangular wave signal into a direction discrimination circuit and processing it, a pulse signal corresponding to the direction of movement of the object is extracted.

Count this up with a counter! There is a known device that detects the position by going down, and is used in NC devices and the like.

The above pulse encoders include rotary type and linear type, and their signal generation methods include optical type, magnetic type, brush type, etc. However, in order to increase the resolution of the detection position, it is necessary to generate the above-mentioned rectangular wave signal. This is not preferable because the number of slits must be increased, and the pulse encoder must be larger or the processing must be more precise.

In view of these points, the “Sensor Technology” Information Investigation Committee published 1
March 984 issue (Vol, 4. No, 3) P, 23~
As shown in FIG. 25 (FIG. 5), a method has been proposed in which the resolution of the detected position is increased by increasing the frequency of the signal generated by the encoder by four times.

However, according to the above method, the circuit configuration for generating pulses of four times the frequency from the encoder output becomes complicated, and
This has the disadvantage that the capacity of the counter for counting the pulses increases, leading to increased costs.

(c) Problems to be Solved by the Invention In view of the above-mentioned problems, an object of the present invention is to provide a high-resolution position detection device at low cost.

(d) Means for solving the problem Therefore, in the present invention, two rectangular wave signals output from a pulse encoder are input into a direction discrimination circuit to generate pulses corresponding to the direction of movement, and the pulses are counted to determine the position. While using the upper digits of the information, we focused on the fact that the level of the rectangular wave signal changes within one cycle.

The device is characterized in that the lower digits of the position information are decoded and output based on this signal change.

(e) If two rectangular wave signals output from the action pulse encoder are used, there will be four combinations of different logic levels at equal intervals during one cycle, and if only one of the above rectangular wave signals is used, there will be different combinations. There are two logical levels. Utilizing this, a rectangular wave signal is input to a decoder, four or two signal states are formed during one period of the rectangular wave signal, and these are used as lower digits of position information. This makes it possible to detect the position with a resolution four times or twice that of the output pulses of the pulse encoder without providing a frequency multiplication circuit.

(F) Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an apparatus according to an embodiment of the present invention.

In the figure, a pulse encoder 1 is attached to one end of a drive shaft 2, and each time this drive shaft 2 rotates by a predetermined angle, a pulse encoder 1 is connected to a pulse encoder 1 at a duty ratio of -50% with a phase shift of 90 degrees.
Two pulse signals PA and PB are generated, and these pulse signals PA and PB are applied to an up-down pulse generation circuit 10 and a decoder 11.

The up-down pulse generation circuit 10 generates an up-count pulse signal PU in synchronization with the rising edge of the pulse signal PA when the drive shaft 2 is rotating in the normal rotation direction and the pulse signal PA is ahead of the pulse signal PB. However, when the drive shaft 2 is rotating in the reverse direction and the pulse signal PA is delayed in phase than the pulse signal PB, the pulse signal PA
A down count pulse signal PD is generated in synchronization with the rising edge of . The up-count pulse signal Pu is input to the up-count input terminal of the up-down counter 12, and the down-count pulse signal PD is input to the down-count input terminal of the up-down counter 12.

The up-down counter 12 counts up when an up-count pulse signal PU is applied, counts down when a down-count pulse signal PD is applied, and converts the n-bit count data into an (n+2)-bit position detection signal. It is output as the upper one digit of , that is, bits D2-Dn+1.

By the way, since the pulse signal PA and the pulse signal PB have the same waveform with a duty of -50% and are out of phase with each other by 90 degrees, in one period of the pulse signal P^, the logic of the pulse signal PA and the pulse signal PB is Four different combinations of levels are obtained, and these four states occur at approximately equal intervals. Therefore, by distinguishing between these four states, the position can be detected with substantially four times the resolution of the pulse signals PA and PB.

Using this fact, the decoder 11 uses the pulse signal PA
, PB outputs a binary signal having four different levels based on a combination of logic levels, and the output signal is output as a signal of the lower two digits of the 1 position detection signal, that is, bits DO and DI.

In this way, a position detection signal of (n+2) digits having a resolution four times that of the pulse encoder 1 is output to the next stage control circuit, etc.

FIG. 2 shows a specific example of the up-down pulse generation circuit 10 described above.

In the figure, a pulse signal PA (see FIG. 3(a)) is applied to a rising differentiation circuit 10a and is also applied to a rising differentiation circuit 10c via an inverter 10b. The pulse signal Pi (see FIG. 3(e)) is output at the rising timing of the signal PA, and the pulse signal P2 (see FIG. 3(f)) is output from the rising differentiation circuit 10c at the rising timing of the pulse signal PA. Output. These pulse signals PL and P2 are applied to one input terminal of AND circuits 10d and 1Oe, respectively.

Furthermore, a pulse signal PB is applied to the value input terminals of the AND circuits 10d and 10e via an inverter 10f, and therefore, when the pulse signal PR is at H level, the AND circuits 10d and 10a are enabled to operate. Become.

Therefore, as shown on the left side of FIG. 3(a)-(h), the drive shaft 2 rotates forward and the pulse signal PA changes to the pulse signal P.
In a state where the phase is ahead of a, the pulse signal P1 generated when the pulse signal PB is at the H level passes through the AND circuit 10d and is output as an up-count pulse Pu.

Furthermore, as shown on the right side of FIGS. 3(a) to (h), when the drive shaft 2 is reversed and the pulse signal PA is delayed in phase than the pulse signal PR, when the pulse signal PB is at H level, The generated pulse signal P2 passes through the AND circuit 10e and is output as a down count pulse PD.

In this way, depending on the phase relationship between the pulse signals PA and PB, the up count pulse PU or the down count pulse PD is generated in synchronization with the rise of the pulse signals PA and PA.

FIG. 4 shows a specific example of the decoder 11 mentioned above.

In the figure, pulse signal PA is inverted via inverter lla, output as a signal of bit D1, and is also applied to one input terminal of exclusive OR circuit 11b. Further, a pulse signal PB is applied to the value input terminal of this exclusive OR circuit 11b, and its output signal is outputted as a bit 00 signal.

Therefore, as shown on the left side of FIGS. 5(a) to 5(d), the drive shaft 2 rotates forward and the pulse signal PA changes to the pulse signal P.
In a state where the phase is ahead of B, the pulse signal PB is at the positive level at the timing when the pulse signal PA rises and the signal D1 falls, so the signal DO goes to the L level,
When the pulse signal Pa reaches the H level after a quarter cycle has passed, the signal DO becomes the H level.

Furthermore, when the pulse signal PA falls and the signal D1 becomes H level after a quarter period has elapsed, the signal DO falls again, and furthermore, when the pulse signal PB falls after a quarter period has elapsed, the signal DO falls again. Signal DO rises to H level. The above operation is similarly executed in each period of the pulse signal PA, and the level states of the signals Do and Di change.

As a result, while the pulse signal PA changes one cycle from its rise, the signals Do and DI change to ro, oJ, ro,
I.J.

The four states of ri, oJ, rl, and IJ are expressed by a pulse signal P.
It changes repeatedly in that order every quarter period of A, and thereby changes so that the lower two digits of the position detection signal are incremented at a frequency four times that of the pulse signal PA.

Furthermore, as shown on the right side of FIGS. 5(a) to (d), when the drive shaft 2 is reversed and the pulse signal PA is in a phase lagging behind the pulse signal PB, the pulse signal PA falls and the signal At the timing when Di rises, the pulse signal PB
is at the H level, the signal DO goes to the H level, and when the pulse signal PB goes to the H level after a quarter of a cycle has passed, the signal DO goes to the L level, and then after another quarter of a cycle has passed, the signal DO goes to the H level. When the pulse signal PA falls and the signal D1 becomes L level, the signal DO rises again, and furthermore,
The operation of 0 or more in which the signal DO falls to the L level when the pulse signal PR falls after a quarter period has passed is performed in the same way in each period of the pulse signal PA, and the signals Do, D
The level state of i changes.

As a result, while the pulse signal PA changes one cycle from its falling edge, the signals Do and Di change to "1, 1", rt, o.
The four states J, rO, IJ, ro, and oJ are repeatedly changed in that order every quarter period of the pulse signal PA,
As a result, the lower two digits of the position detection signal become the pulse signal P
It changes so that it is decremented at a frequency four times that of A.

In this way, the lower two digits of the position detection signal DO,
DI depends on the phase relationship between pulse signals PA and PB.

It changes to be incremented or decremented at a frequency four times that of the pulse signal PA, and as a result, a resolution four times that of the pulse encoder 1 can be obtained.

FIG. 6 shows another embodiment of the present invention. In addition, in this figure, the same parts as in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, the direction discrimination circuit 14 lowers the up-down signal Sud to L level when the pulse signal PA is ahead of the pulse signal PB, and lowers the up-down signal Sud to L level when the pulse signal PA is behind the pulse signal PB. It raises Sud to H level and outputs pulse signals PA and a clock signal CPa synchronized with the rising edge of PA.
5 is applied to the up/down input terminal and the clock input terminal respectively.

The up/down counter 15 counts up by the clock signal CPa applied to the clock input terminal when the up/down signal Sud applied to the up/down input terminal is at L level, and also counts up by the clock signal CPa applied to the clock input terminal.
Clock signal CP applied when d is at H level
A is counted down, and the counted value is output to the next stage device as the upper 0 digits of the position detection signal, that is, bit D2-On+1. In addition, the lower 2 of the position detection signal
The digit signals Do and Di are.

It is output from the decoder 11.

FIG. 7 shows a specific example of the direction discrimination circuit 14. This direction discrimination circuit 14 converts the output signals from the up/down pulse generation circuit 10 described in FIG. The clock signal CPa is output via the clock signal CPa. At the same time, pulse signals PA and PB are applied to the clock input terminal GK and data input terminal of the flip-flop 14h, respectively, at the timing shown in FIG. Output as .

FIG. 9 shows still another embodiment of the present invention. In addition, in this figure, the same parts as in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, pulse signals PA and PB output from a pulse encoder 1 are transmitted to an up-down pulse generation circuit 10.
The microcomputer 20 performs a logical operation similar to that of the decoder 11 described above to obtain the lower two digits of the position detection signal DO, D.
The contents of i are determined.

Further, the count value of the up/down counter 12 is added to the microcomputer 20 as signals D2 to On+1 of the upper 0 digits of the position detection signal.

In each of the above embodiments, the upper digit of the 1-position detection signal is generated by an up/down counter, but the same effect can be obtained by using two forward rotation counters and two reverse rotation counters. Further, the output signal of the decoder may be one that outputs only the signal D1 depending on the required resolution.

Furthermore, it goes without saying that the configurations of the up-down pulse generation circuit and the direction discrimination circuit are not limited to those described above.

(G) Detailed Description of the Invention According to the present invention, two rectangular wave signals output from a pulse encoder are input into a direction discrimination circuit to generate pulses corresponding to the moving direction, and these pulses are counted. While using the upper digits of the position information, we focused on the fact that the level of the rectangular wave signal changes within one cycle, and decoded and output the lower digits of the position information from this signal change. A position detection device capable of high-resolution position detection is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. Figure 2 is a circuit diagram showing an example of an up-down pulse generation circuit, Figures 3(a) and (h) are waveform diagrams for explaining the operation of the circuit shown in Figure 2, and Figure 4 is a diagram of a decoder. A circuit diagram showing an example, FIGS. 5(a) to 5(d) are waveform diagrams for explaining the operation of the circuit shown in FIG. 4, and FIG. 6 is a block diagram showing another embodiment of the present invention. 7 is a circuit diagram showing an example of a direction discrimination circuit, FIGS. 8(a) to (c) are waveform diagrams for explaining the operation of the circuit shown in FIG. 7, and FIG. 9 is a circuit diagram showing an example of the direction discrimination circuit. FIG. 7 is a block diagram showing still another embodiment of the invention. 1... Pulse encoder, 10... Up/down pulse generation circuit, 11... Decoder, 12.15...
・Up/down counter, 14...Direction discrimination circuit, 2
0...Microcomputer. Figure 1 Figure 2

Claims (1)

[Claims] A pulse encoder generates two rectangular wave signals whose phases lead and lag by a predetermined angle in accordance with the moving direction of the object, and a pulse encoder that determines the moving direction of the object from the phase relationship of the two rectangular wave signals, and generates the rectangular wave signal. pulse generating means for generating a pulse signal synchronized with the cycle of the pulse signal; counting means for counting the pulse signal and outputting the upper digits of the position information of the object; and calculating the lower digits of the position information of the object from the rectangular wave signal. 1. A position detection device comprising: a decoding means for outputting a decoding means.