JPS6016580B2 - Movement direction discrimination circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit that determines the moving direction of an object, and in particular, the present invention relates to a circuit that determines the moving direction of an object when the object moves between at least two sets of detectors capable of detecting the presence or absence of an object. Regarding the moving direction discrimination circuit, which extracts the discrimination output according to the moving direction and uses it for identifying the direction of the moving object, counting the number of objects, etc. This allows the direction of movement of an object to be correctly determined regardless of the passing pattern, such as whether the object travels backwards during the passage.

For example, two sets of photodetectors capable of detecting the presence or absence of an object are arranged on both sides of an object path, and when an object passes through the path, a logical circuit determines the order of the detection signals from the photodetectors. However, various circuit devices have been proposed that extract a direction discrimination output according to the direction of movement and provide it for the various types of control as described above.

For example, FIG. 1 schematically shows an example of a device of this type, where A indicates a moving object, and on each side of the path of movement of this object A (indicated by solid and dotted arrows in the figure), first detectors are arranged. The light projector S and the light receiver R constituting the detector, and the light projector S2 and the light receiver R2 of the second detector are arranged to face each other as shown in the figure.

First and second waveform shaping circuits B each of which can configure the detection signals from the photodetectors R and R2 using Schmitt circuits, etc.
and B2, and the waveform shaped outputs a and a2 from these circuits B and & are applied to a moving direction determining circuit C, where the moving direction of the object A is determined. When the object A moves in the direction of the solid line arrow (assumed to be the positive direction), a positive direction pulse p is obtained from the discrimination circuit C, and when the object A moves in the direction of the dotted line arrow (assumed to be the negative direction), the discrimination circuit A negative direction pulse n is obtained from C. The moving direction determining circuit is configured as shown in FIG. 2, for example, and supplies the signal a taken out from the waveform shaping circuit ear directly to the differentiating circuit 1 and via the inverting element 2 to the differentiating circuit 3. ,
The differential output from the differentiating circuit 1, that is, the differential pulse b at the rising edge of the signal a, and the signal a2 from the waveform shaping circuit are supplied to the AND gate 4. means that the direction of movement is the negative direction).

Furthermore, the differential output from the differentiating circuit 3, that is, the detection signal a,
The differential pulse c at the time of falling and the detection signal a2 are supplied to the AND gate 5, and the AND gate 5 generates a positive direction pulse p (here, the positive direction means that the moving direction is the positive direction). Take out. In this example, AND gates 4 and 5 are controlled by detection signal a2, so that if differential pulse b or c does not occur during the occurrence of signal a2,
That is, if the detection signals a and a2 do not overlap, the direction determination output p or n cannot be obtained. In other words, in this example, the dimensions of the object A and the spacing between the first and second detectors are determined appropriately to obtain the detection signals a and a.
2 overlaps, object A
However, when the detection signals a and a2 do not have overlapping waveforms, such as when the size of the object is smaller than the distance between both detectors, the direction of movement of the object can be determined correctly. However, there is a drawback that neither discrimination signal p nor n is generated. The above drawbacks should be removed〈
, an edge-triggered flip-flop, as shown in FIG.

It is also known that the movement direction determining circuit C is constructed from a NAND element (hereinafter abbreviated as D-FF) and a NAND element. That is, in FIG. 3, detection signals a and a2 are supplied to edge detection circuits 6 and 7, which can each be constructed from a differentiating circuit or the like, to extract edge detection signals corresponding to each rise of the signals a and a2. The signal from edge detection circuit 6 is applied to D-FF 8 and NAND element 9, and the signal from edge detection circuit 7 is applied to D-FFIO and NAND element 11. The other input terminal of the NAND element 9 has a D-FFIO
The output of D is added to the other input terminal of the NAND element 11.
-Add the output of FF8. A negative direction pulse n is taken out from the NAND element 9, and a positive direction pulse p is taken out from the NAND element 11. Both positive and negative pulses p and n are connected to NAND element 1
2 to a one-shot pulse generator 13, and when either the positive direction pulse p or the negative direction pulse n is generated, the pulse generator 13 is operated to generate one pulse, and this pulse as a reset pulse D
- In addition to FF8 and FF1, the states of these D-FFs are restored to their original state. In the circuit arrangement shown in the third diagram, when a moving object returns in the middle of passing in the positive direction, it passes through the first detector twice, and when it returns in the middle of passing in the negative direction, it passes through the second detector twice. Therefore, in either case, both positive and negative direction pulses p and n are generated, and the moving direction cannot be determined. It is an object of the present invention to eliminate the above-mentioned drawbacks and to be able to adapt to various forms of movement of an object without being controlled by two detection signal generation patterns, regardless of the size of the shape of the object. It is an object of the present invention to provide a moving direction determining circuit that can correctly determine the moving direction. The present invention includes at least two sets of detectors capable of detecting the presence or absence of an object, and generates a moving direction discrimination signal according to the moving direction of the object when the object moves and passes through a sensitive area formed by the detectors. an approach direction determining circuit that determines the direction in which the object approaches the sensitive area and holds the result of the determination of the approaching direction; and an approach direction determining circuit that determines the direction in which the object advances from the sensitive area. an advancing direction determining circuit that retains a result of determining the advancing direction of the object; a pulse generating circuit that generates a pulse immediately after the object advances from the sensitive area;
a gate circuit that is supplied with the approach direction determination result, the advance direction determination result, and the pulse, and extracts the pulse as a moving direction determination signal only when the approach direction determination result and the advance direction determination result match; The present invention is characterized by comprising a set circuit that resets the approaching direction determining circuit and the advancing direction determining circuit after occurrence of the above.

In the present invention, the number of objects can also be counted by supplying the output of the gate circuit to a counter.

The present invention will be explained in detail below with reference to the drawings.

An embodiment of the circuit of the present invention is shown in FIG.

Here, the detection signals a and a2 are supplied to an entry direction determination circuit 21 for determining the moving direction at the time when the moving object A enters the detector sensitive area. This discrimination circuit 21
can be configured, for example, as shown in the figure, and the signals a and a2
are applied to the AND gates 22 and 23, respectively, the outputs from the AND gates 22 and 23 are applied to the JK flip-flops 24 and 25, respectively, and the Q outputs of these flip-flops 24 and 25 are applied to the AND gate 22 and 23, respectively.
and 23 in parallel. JK flip flop 2
The Q output signal q is taken out from the JK flip-flop 25 as a positive direction approach determination signal, and the Q output signal Q is taken out from the JK flip-flop 25 as a negative direction approach determination signal. When the moving object A enters the detector sensitive area from the positive direction, the output signal b becomes "1" and the output signal Q becomes "0", and these signal states are determined by the JK flip-flops 24 and 25. Retained until reset. Conversely, when the moving object A approaches from the negative direction, the output signal b becomes "0" and the output signal Q becomes "1". The detection signal a2 is supplied to the advancing direction determination circuit 27 via the OR gate 26.

This discrimination circuit 27 can be configured, for example, as shown in the figure, and supplies the OR output of the OR gate 26 to the NAND gates 29 and 301 via the inverter 28, and supplies the detection signal a. is supplied to the other input terminal of the NAND gate 29, the outputs of the NAND gates 29 and 30 are supplied to the NAND gate 31,
Further, the output of the NAND gate 31 is supplied to the other input terminal of the NAND gate 30. Output signal c of NAND gate 30
, is taken out as a positive direction advancement determination signal, and 2 is taken out as the output signal of the NAND gate 31 as a negative direction advancement determination signal. When the object A advances from the detector sensitive area in the positive direction, the output signal c becomes "1" and the output signal c2 becomes "0", and these signal states are maintained. These signal states are reset when a reset signal is applied to OR gate 26. On the other hand, when the object A advances in the negative direction, the output signal c becomes "0" and the output signal 2 becomes "1".Furthermore, the detection signals a and a2 are supplied to the OR gate 32, and the output signal c becomes "1". OR output d to one-shot pulse generator 3
3, one pulse e is generated at the falling edge of the signal d, that is, when the detection signal a or a2 from the detector disappears.
to occur.

In other words, one pulse is always generated when the object moves out of the sensitive area. Detection signal a. and a2
is also supplied to the reset circuit 34.

The reset circuit 34 can be configured as shown in the figure, and supplies the detection signals a and a2 to the D flip-flops 35 and 36, respectively.
6 Q outputs are applied to an AND gate 37. On the other hand, the pulse e from the one-shot pulse generator 33 is applied to the one-shot pulse generator 38, a pulse is generated at the falling edge of the pulse e, and this pulse is applied to the third input terminal of the AND gate 37. The AND gate 37 takes out the AND output of the output pulse of the one-shot pulse generator 38 and the "1" signal obtained by storing the detection signals a and a2 individually in the D flip-flops 35 and 36. An AND output and a set signal g from the outside are applied to an OR gate 39, and a reset pulse f is taken out from this OR gate 39. This reset pulse f is applied to the flip-flops 24, 25, 35 and 36 and the OR gate 2.
In addition to the other input terminal of 6, these flip-flops and the flip-flop with the naso gate 29 and 31 are returned to their initial states. Furthermore, the signal chi,c
, and e are supplied to an AND gate 41 constituting the final stage gate circuit 40, and signals Q, c2, and e are supplied to an AND gate 42 constituting the final stage gate circuit 40.

In the AND gate 41, the one-shot pulse e is gate-controlled by the forward direction entry determination signal Q and the forward direction advance determination signal c, and the pulse e is output from the AND gate 41 only when both signals 0 and c exist simultaneously. The one-shot pulse e is taken out as a positive direction discrimination pulse p, and in the AND gate 42, the one-shot pulse e is gate-controlled by the negative direction entry discrimination signal and the negative direction advance discrimination signal c2, and when both signals Q and c2 are present at the same time, Only the pulse e is taken out from the AND gate 42 as the negative direction discrimination pulse n.
Note that the above-mentioned external reset signal g can be used, for example, to return the entire discrimination circuit to its initial state when the moving object A returns after only the signal a is detected. . According to the movement direction discrimination circuit of the present invention having the above configuration, even when the moving object moves in the forward direction and the detection signals a and a2 do not overlap, the detection signals a and a2 can be detected as shown in FIGS. 5A to 5K. When a moving object enters from the forward direction and returns halfway, a pulse p indicating the moving direction is obtained as shown in FIGS. 6A to 6K. Neither p nor n is obtained, so the direction of movement is correctly determined.

Note that FIG. 5A and FIG. 6A are the detection signals a,
, Figures 5B and 6B are the detection signal a2, Figures 5C and 6C are the positive wide direction approach discrimination signal, and Figures 5D and 6D are the negative manbound approach discrimination signal wide. , Figures 5E and 6
Figure E is positive direction advancement determination signal c, Figures 5F and 6F are negative direction advancement determination signal c2, Figures 5G and 6G.
is the OR output signal d, the one-shot pulse e in FIGS. 6 and 6, the reset pulse f in FIGS. 5 1 and 6 1, the positive direction pulse p in FIGS. Fifth
Figures K and 6K respectively show a negative direction pulse n.
As described above, according to the present invention, the direction in which the moving object enters the sensitive area of the detector is first determined, the determination result is stored, and then the direction in which the object moves out of the sensitive area is determined. It determines the direction in which the object is moving, stores the determination result, and sends out a determination output pulse representing the direction of movement only when the above two determination results match immediately after the object advances from the sensitive area. Regardless of the pattern of objects passing through the sensitive region and the size of the shape of the objects, the moving direction and the number of objects passing through can be accurately measured.

Therefore, the moving direction discrimination circuit of the present invention arranges two or more sets of sensors capable of detecting the presence of an object, and when an object moves and passes through a sensitive area between the sensors, it also obtains a signal indicating the moving direction and performs control. It is extremely effective when it is necessary to measure an object on a belt conveyor, the rotation direction or rotation angle of a rotating body, or the number of axes of a passing vehicle. The number of objects can be easily counted by counting the positive direction pulses and the negative direction pulses with a counter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the general configuration of a moving direction determining device, FIGS. 2 and 3 are block diagrams showing two conventional examples of the moving direction determining circuit, and FIG. 4 is a block diagram showing the present invention. Block diagram illustrating an example of the configuration of the moving direction determination circuit, No. 5
FIGS. A to K and FIGS. 6A to 6K are signal waveform diagrams of various parts for explaining the operation of the circuit of FIG. 4. S,, S2... Emitter, R,, R2... Light receiver, A... Moving object, B, B... Waveform shaping circuit, C...・Movement direction discrimination circuit, a,, a2
...Detection signal, p...Shimamanko pulse,
n... Negative direction pulse, 21... Approach direction discrimination circuit, 22, 23, 37, 41, 42... AND gate, 24, 25... JK flip-flop, 26,
32, 39...OR gate, 27...Advancing direction determination circuit, 28...Inverter, 29,30,31
...Nand Gate, 33, 38. ．．・．． ．．・One-shot pulse generator, 34. ．．・．． ．． Reset circuit, 35
, 36...D flip-flop, 40...
・・Final stage gate circuit, q・・・・Shoman direction approach discrimination signal, Q・・・・Negative direction approach discrimination signal, c. ...Forward direction advancement determination signal, c...Credit direction advancement determination signal, d...OR output, e...One shot pulse, f.・・・． -Reset pulse, g...External reset signal. Number 1 Figure 2 Tsutomu 3 Traditional 5 Figure Traditional 4 Traditional G

Claims (1)

[Claims] 1. At least two sets of detectors capable of detecting the presence or absence of an object are provided, and when the object moves and passes through a sensitive area formed by the detectors, the moving direction is determined according to the moving direction of the object. A moving direction determining circuit that generates a signal includes an entering direction determining circuit that determines the direction in which the object is entering the sensitive area and retains the result of determining the approaching direction; an advancing direction determination circuit that determines the direction and holds the advancing direction determination result; a pulse generating circuit that generates a pulse immediately after the object advances from the sensitive area; the advancing direction determination result, the advancing direction determination result, and a gate circuit that is supplied with the pulse and extracts the pulse as a moving direction discrimination signal only when the result of the approach direction discrimination and the result of the advance direction discrimination match; and the approach direction discrimination circuit and the advance direction after the pulse is generated; A moving direction discriminating circuit comprising: a reset circuit for resetting the discriminating circuit. 2. A moving direction determining circuit according to claim 1, characterized in that the output of the gate circuit is supplied to a counter to count the number of objects. 3. A movement direction determining circuit according to claim 1 or 2, characterized in that the number of sets of the detectors is two. 4. A movement direction determining circuit according to any one of claims 1 to 3, characterized in that one set of detectors includes a light projector and a light receiver. 5. In the circuit according to claim 3, the approach direction determining circuit includes first and second AND gates and a first
and a second JK flip-flop, and the first AND gate receives a first detection signal from the first detector and a second JK flip-flop.
and (2) output from the second JK flip-flop, and add the second detection signal from the second detector and (2) output from the first and second JK flip-flops to the second AND gate. The output of the second AND gate is supplied to the first JK flip-flop, the output of the second AND gate is supplied to the second JK flip-flop, the Q output of the first JK flip-flop is taken out as a first direction entry determination signal, and the Q output of the second JK flip-flop is taken out as a first direction entry determination signal. A moving direction discrimination circuit characterized in that an output is taken out as a second direction approach discrimination signal. 6. In the circuit according to claim 5, the advancing direction determining circuit includes an inverter and first, second, and third
a NAND gate, the first detection signal is supplied to the first NAND gate, the second detection signal is supplied to the first NAND gate via the inverter, and the output of the inverter and the output of the third NAND gate are Said second
In addition to the NAND gate, the output of the first NAND gate and the output of the second NAND gate are added to the third NAND gate, a first direction advance determination signal is extracted from the second NAND gate, and a second direction advance determination signal is extracted from the third NAND gate. A moving direction determining circuit characterized in that the circuit extracts the moving direction. 7. The circuit according to claim 6, wherein the pulse generating circuit comprises an OR gate supplied with the first and second detection signals, and a one-shot circuit that generates one pulse when the output of the OR gate falls. A moving direction determining circuit comprising a pulse generating circuit. 8. In the circuit according to claim 7, the gate circuit includes the first direction approach determination signal, a third AND gate supplied with the first direction approach determination signal and the pulse, and the second a fourth AND gate supplied with a direction entry determination signal, the second direction advance determination signal, and the pulse; the first direction determination signal is taken out from the previous third AND gate; A moving direction discrimination circuit characterized in that a direction discrimination signal is extracted. 9. In the circuit according to claim 8, the reset circuit includes first and second D flip-flops supplied with the first and second detection signals, respectively, and a 1 second when descending
a one-shot pulse generation circuit that generates a pulse; a fifth AND gate that is supplied with each Q output of the first and second D flip-flops and the second pulse; and an output of the fifth AND gate and a reset signal from the outside. A second OR gate is provided with
The second detection signal and the reset signal are supplied to each reset input terminal of the first and second D flip-flops, the second detection signal and the reset signal are supplied to a third OR gate, and the output of the third OR gate is applied to the inverter. A moving direction discrimination circuit.