JPH0465356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Purpose This invention relates to a detection device for detecting the presence of work cloth.

Prior Art Conventionally, when detecting a passing work cloth using a detection device that detects the presence of a work cloth, for example, a photoelectric detector consisting of a light emitting element and a light receiving element, the work cloth is illuminated with light. The presence or absence of the object to be detected was detected based on the presence or absence of reflected light. and,
When the formation or material of the work cloth changes, it is necessary to change the detection distance of the detector each time. In that case, the detection level (sensitivity) also changes, making it necessary to readjust the detection level of the detector.

In addition, in processing machines or equipment equipped with a large number of the above-mentioned photoelectric detectors, one
There was a defect that required a lot of effort and time to adjust the level. Moreover, this adjustment varied depending on the operator, and it was not possible to unify the adjustment to a uniform level.

Purpose This invention was made to solve the above-mentioned problems, and its purpose is to:
Processing that can automatically adjust the level (sensitivity) of the detection device to the optimal level even if the detection distance is changed in response to changes in the shape or material of the workpiece cloth, eliminating the labor of adjustment work. To provide cloth detection equipment.

Embodiment Hereinafter, an embodiment in which the present invention is embodied in a work cloth detection device for a sewing machine will be described with reference to the drawings.

In FIG. 1, first and second cloth end detectors 1 and 2 and first to fourth cloth side edge detectors 3 to 6 as detectors are light emitting diodes 1a to 6a, respectively.
and phototransistors 1b to 6b, as shown in FIG. 2 (the third and fourth cloth side edge detectors 5 and 6 are not shown), an upper plate and a separating plate 7a,
It is disposed at a predetermined position on the upper plate 7a of the workpiece cloth guide device 7 and the sewing machine table 8, which are made up of a workpiece cloth guide device 7 and the like. The light from each of the light emitting diodes 1a to 6a is irradiated onto the upper or lower surface of the separation plate 7b, and the reflected light is received by the phototransistors 1b to 6b, which pass through the work cloth guide device 7. The end ends and side ends 9a, 10a of the two work cloths 9, 10 sent to the sewing position are detected, respectively.

Each of the light emitting diodes 1a to 6a has a resistance of 1
1 and a pulse oscillator 1 via a power amplifier 12
3, and the pulse signal from the oscillator 13
A constant cycle point reduction operation is performed by a constant cycle pulse voltage applied based on SG1. on the other hand,
Each phototransistor 1b to 6b is a driver 2 to be described later.
Analog switches SW1 to 8 serve as switching means that are controlled on and off based on control signals from 8.
SW6, bandpass filter 14 for noise removal
and is connected via an amplifier 15 to a comparator 16 as comparison means. Then, only one of the six analog switches SW1 to SW6 is turned on based on a control signal from a driver 28, which will be described later, and the phototransistor corresponding to the turned-on analog switch is turned on. The off signal (detection signal) is passed through the bandpass filter 14 and amplifier 15 to the detection output voltage Vo.
It is output to the comparator 16 as .

The comparator 16 receives a reference voltage Vs from a D-A converter as reference voltage changing means to be described later.
is input, the reference voltage Vs is compared with the detected output voltage Vo, and the output voltage Vo becomes the reference voltage Vs.
When it is larger, an output signal SG2 of positive potential (hereinafter referred to as H level) is output to the AND circuit 17. The AND circuit 17 outputs an output signal SG2a based on an H level control signal SG3 from an interface 25, which will be described later, and the output signal SG2.

The octal counter 18 is a subtraction counter, and
The output signal SG2a of the AND circuit 17 subtracts the content from the state set to the value "8", and when eight output signals SG2a are input and the content becomes "0" (count 0 potential (hereinafter referred to as L level) borrow signal
SG4 is the first flip-flop circuit (hereinafter referred to as the first flip-flop circuit).
The output signal SG5 of the FF circuit 19 is inverted from the L level to the H level.

The decimal counter 20 is a subtraction counter,
The content is subtracted from the value set to "10" by the pulse signal SG1 of the pulse oscillator 13, and when 10 pulse signals SG1 are input and the content becomes "0" (count up). ), the borrow signal is output to the set side input terminal of the second flip-flop circuit (hereinafter referred to as the second FF circuit) 21, and the output signal SG of the FF circuit 21 is output.
6 is inverted from H level to L level.

The microcomputer MC includes a central processing unit (hereinafter referred to as CPU) 22 which mainly constitutes a reference voltage change control means, a discrimination means, an indexing means, an appropriate output voltage calculation means, and a detection control means, and a programmable read-only memory (hereinafter referred to as PROM). )
23, it is composed of a readable and writable memory (hereinafter referred to as RAM) 24 as a storage means and interfaces 25 and 26, and the output signal SG6 from the second FF circuit 21 is sent to the CPU 2.
2, the output signal SG5 from the first FF circuit 19
is input to the CPU 22 via the interface 26. Also, CPU22 is interface 2
5 to the AND circuit 17, and outputs a reset signal SG7 to the octal and decimal counters 18 and 20 and the first and second FF circuits 19 and 21. When the reset signal SG7 becomes L level, the contents of the octal and decimal counters 18 and 20 are preset to "8" and "10" respectively, and the same signal is
When SG7 is at H level, the output signal is
The subtraction operation is performed based on SG2a and pulse signal SG1. Also, the first and second FF
The circuits 19 and 21 are inverted when the reset signal SG7 goes to L level, and the output signal SG5 goes from H level to L level, while the output signal SG6 goes from L level to H level.

Furthermore, the CPU 22 uses the data stored in the RAM 24 and the contents of the accumulator in the CPU 22 to access the D-
A change command signal SG8 is sent to the A converter 27 to control the stepwise change in the level of the reference voltage Vs output to the comparator 16, and the driver 28 is made to turn on any one of the six analog switches SW1 to SW6. Drive control signal SG9 for
Output.

As shown in FIG.
- An eighth register is prepared, the first register is a detector selection register and contains selection data for turning on any one of the analog switches SW1 to SW6, and the second register is a detection result register. The storage instruction register is a storage instruction data indicating the type of the selected detector, and the third to eighth registers contain adjustment voltages provided corresponding to each of the detectors 1 to 6. These storage registers store reference voltage command data for causing the D-A converter 27 to output the optimum reference voltage Vs for each of the detectors 1 to 6, respectively.

The start switch 29 is provided on an operation panel (not shown) of the sewing machine, and an ON signal based on the operation of the switch 29 is outputted to the CPU 22 via the interface 26. An indicator lamp 30 made of a light emitting diode is also provided on the operation panel, and its lighting is controlled based on a drive signal output from the CPU 22 via a resistor 31 and an interface 25.

Next, the operation of the workpiece cloth detecting device constructed as described above will be explained according to the flowchart of the CPU 22 shown in FIG.

Now, the first and second cloth end detectors 1 and 2
When the start switch 29 is turned on to adjust the sensitivity of the first to fourth cloth side edge detectors 3 to 6, the CPU 22 initializes the contents of the first and second registers of the RAM 24 to "1". At the same time, the third
~Clear the contents of the 8th register. Also CPU2
2 initializes the first and second FF circuits 19 and 21, and also sets the octal and decimal counters 18 and 2.
Set the contents of 0 to "8" and "10", respectively.
Furthermore, as the start switch 29 is turned on,
The pulse oscillator 13 starts its oscillation operation. Then, each of the light emitting diodes 1a to 6a starts a dimming operation, and each of the phototransistors 1b to 6b is turned on and off.

Subsequently, the CPU 22 sends a drive control signal SG9 to the driver 28 to turn on the analog switch SW1, based on the content "1" of the first register.
At the same time, the accumulator (hereinafter referred to as Acc) in the CPU 22 is set to 0, and then 1 is added to make its content ``1''. By turning on the analog switch SW1, the first
A detection signal from the cloth end detector 1 is outputted to an amplifier 15 via a bandpass filter 14. Then, the amplifier 15 amplifies this detection signal and outputs the detection output voltage Vo shown in FIG. 5 to the next stage comparator 1.
It will be output to 6.

Next, the CPU 22 outputs the content "1" of Acc to the DA converter 27 as a change command signal SG8. In response to this change command control signal SG8, the DA converter 27 outputs a reference voltage V _s1 corresponding to the content "1" of Acc to the comparator 16, as shown in FIG. As a result, comparator 16
compares and discriminates the detected output voltage Vo with the reference voltage V _s1 and outputs an output signal SG2 to the AND circuit 17 at the next stage as shown in FIG.

When the comparator 16 starts a comparison operation based on the reference voltage _Vs1 , the CPU 22 outputs an H level control signal SG3 and a reset signal SG7.
In response to this reset signal SG7, the decimal counter 20 starts a subtraction operation based on the pulse signal SG1, and the octal counter 18 also starts subtraction based on the output signal SG2a from the AND circuit 17 based on the output signal SG2. Start operation.

When the octal counter 18 inputs eight output signals SG2a and counts up, the counter 18
is the borrow signal SG at L level as shown in FIG.
4 and inverts the first FF circuit 19.
As a result, the output signal SG5 of the first FF circuit 19 becomes H level and is output to the CPU 22. Subsequently, when the decimal counter 20 inputs 10 pulse signals SG1 and goes out, the counter 20 outputs a borrow signal and inverts the second FF circuit 21. As a result of this inversion, the output signal SG6 of the second FF circuit 21 becomes L level as shown in FIG. 5 and is output to the CPU 22.

In response to the L level output signal SG6, the CPU 22 first sets the control signal SG3 to the L level,
After stopping the subtraction operation of the octal counter 18, the level of the output signal SG5 of the first FF circuit 19 is checked. At this time, the output signal SG5 is H
level, the CPU 22 outputs the reset signal SG7 at the L level, and each FF circuit 19,
21 and each counter 18,
20 is preset.

Subsequently, the CPU 22 adds 1 to Acc to make its content "2", and then outputs the content to the DA converter 27 as a change command signal SG8. In response to this change command control signal SG8, the D-A converter 27 outputs the reference voltage V _s2 (>V _s1 ) corresponding to the content "2" of Acc to the comparator 1 as shown in FIG.
Output to 6. Therefore, the comparator 16 converts the detected output voltage Vo into a new reference voltage that is larger than the reference voltage V _s1 based on the content "1" of the Acc.
A comparison is made with V _s2 and an output signal SG2 is output to the AND circuit 17 at the next stage.

When the comparator 16 starts the comparison operation based on the reference voltage V _s2 , the CPU 22 outputs the H level control signal SG3 and reset signal SG7 as before.
is output, and the subtraction operation of the octal counter 18 and the decimal counter 20 is started. Then, when the eight output signals 2a are input and the octal counter 18 outputs an L level borrow signal SG4, the first FF circuit 19 is inverted and outputs an H level output signal SG5.
Output to CPU22. Subsequently, when 10 pulse signals SG1 are input and the decimal counter 20 outputs a borrow signal, the second FF circuit 21 is inverted,
An L level output signal SG6 is output to the CPU 22.

In response to this L-level output signal SG6, the CPU 22 first lowers the control signal SG3 as described above.
After the subtraction operation of the octal counter 18 is stopped, an L level reset signal SG7 is outputted to each FF circuit 1 based on the fact that the output signal SG5 of the first FF circuit 19 is at the L level.
9 and 21, and each counter 1
8 and 20 are preset. After that, the CPU
22 sequentially adds the contents of Acc one by one, changes it to a new reference voltage Vs that increases in accordance with the contents, and makes the comparator 16 compare and discriminate the detected output voltage Vo, and the octal and decimal counters 18 and 20 Repeat the counting operation.

Then, the operation is repeated N times, and the content of Acc becomes "N", and the reference voltage Vsn (≫V _s2 ) corresponding to the content "N", which is larger than the detected output voltage Vo, is input to the D-A converter 27. and converter 2
7, the output signal SG2 is no longer output. As a result, the subtraction operation of the octal counter 18 is not performed, and the output signal SG5 input from the first FF circuit 19 to the CPU 22 remains at the L level.

On the other hand, the decimal counter 20 performs a subtraction operation based on the pulse signal SG1, and converts the borrow signal into a second one.
When the output signal is output to the FF circuit 21 and the FF circuit 21 is inverted, the CPU 22 outputs the output signal SG of the first FF circuit 19 in response to the L level output signal SG6.
Perform the level check in step 5.

At this time, the output signal SG5 is at the L level, so the CPU 22 exits the sensitivity adjustment operation and goes to the L level.
A level reset signal SG7 is output to reset each FF circuit 19, 21 and preset each counter 18, 20. continue,
The CPU 22 subtracts 2 from the contents of Acc, “N”, and calculates “N−”.
2". This processing operation is performed at the optimum reference voltage Vs
It is a processing operation for setting the content "N-
The reference voltage V _so-2 corresponding to "2" is the reference voltage
It is lower than Vsn and has a voltage value that allows reliable detection of the detection output voltage Vo output based on the on/off operation of the phototransistor 1a of the first cloth end detector 1 without discarding noise.

After the CPU 22 sets the contents of Acc to "N-2",
The same content "N-2" is stored in the third register of the RAM 24 as the reference voltage command data of the first cloth end detector 1 according to the content "1" of the second register.
Subsequently, the CPU 22 increments the contents of the first and second registers to "2", and then checks whether sensitivity adjustment of all the detectors 1 to 6 has not been completed yet. Next, the CPU 22 outputs a drive control signal SG9 for turning on the analog switch SW2 to the driver 28 based on the content "2" of the first register, and proceeds to the sensitivity adjustment operation of the second cloth end detector 2. Then, the same operation as above is performed to obtain the reference voltage command data of the second cloth end detector 2 and store it in the fourth register.

Thereafter, the reference voltage command data of the 1st to 4th cloth side edge detectors 3 to 8 will be transferred to the 5th one of the RAM 24 in the same manner.
~ Stored in the 8th register. When the sensitivity adjustment of all detectors 1 to 6 is completed, CPU 2
Step 2 moves to the detection operation of the work cloths 9 and 10.

Next, the detection operation will be briefly explained.

The CPU 22 sets the contents of the first and second registers to "1" and outputs an L level reset signal SG7 to preset each counter 18, 20 and reset each FF circuit 19, 21. Next, the CPU 22 turns on the analog switch SW based on the content "1" of the first register.
A drive control signal SG9 is output to the driver circuit 28 to turn on the drive control signal SG1. Next, CPU22 is the second
Based on the register content "1", the reference voltage command data of the first cloth end detector 1 stored in the third register is read out and sent to D-A as a change command signal SG8.
Output to converter 27. D-A converter 2
7 is the reference voltage based on this command signal SG8.
Output V _so-2 to comparator 16. Then the CPU
22 outputs a control signal SG3 and a reset signal SG7 of H level to start the subtraction operation of each counter 18, 20, and execute the detection operation of the first cloth end detector 1.

At this time, if the work cloth 9 is present in the first cloth end detector 1 as shown in FIG. 3, the detected output voltage Vo becomes 0 (<V _so-2 ) and the octal counter 1
8 does not perform a subtraction operation and does not output an L-level borrow signal SG4. On the other hand, when there is no work cloth 9, the detected output voltage Vo is the same as the output voltage during the sensitivity adjustment, so the octal counter 18 outputs eight output signals SG.
After inputting 2a, it counts up and outputs an L level borrow signal SG4. Therefore, when the work cloth 9 is present, the output signal SG5 is at L level, and when it is not present, the output signal SG5 is at H level.

Then, when the decimal counter 20 counts up and an L level output signal SG6 is output to the CPU 22, the CPU 22 outputs the first FF circuit 19.
A level check is performed on the output signal SG5. It is determined that the work cloth 9 is present when the output signal 5 is at the L level, and that the work cloth 9 is not present when the output signal 5 is at the H level.

When the workpiece cloth detection operation of the first cloth end edge detector 1 is completed, the contents of the first register are incremented, and the next workpiece cloth detection operation of the second cloth end edge detector 2 is started in the same manner as described above. This is done based on the reference voltage command data of 4 registers. Then, after sequentially performing the work cloth detection operations of the first to fourth cloth side edge detectors 3 to 6 in the same manner as described above, the first cloth end edge detector 1 is again operated.
Returning to the detection operation, from then on, the first cloth end detector 1
The detection operations from to to the fourth cloth side edge detector 6 are repeated many times to detect the workpiece cloths 9 and 10.

In this way, in this embodiment, before detecting the work cloths 9 and 10, the sensitivity of each of the detectors 1 to 6 is automatically adjusted in advance, the optimum sensitivity of each of the detectors 1 to 6 is determined, and the data is is stored in the RAM 24, and during training, each detector 1 to 6 is operated to detect the workpiece cloths 9 and 10 in the optimal sensitivity state based on the data, so the labor of sensitivity adjustment work can be eliminated, and each The accuracy of the detectors 1 to 6 can be increased.

Note that the present invention is not limited to the above-mentioned embodiments, and may be modified as appropriate without departing from the gist of the present invention, such as application to a detector consisting of a Hall element and a magnet.

Effects As described in detail above, in the present invention, the reference voltage change control means gives a change command to the reference voltage change means prior to the detection operation of the work cloth of the detection device, and steps the output voltage in a predetermined order. an output voltage of the reference voltage changing means that is sequentially increased or decreased based on the change command from the reference voltage changing control means;
A reversal of the magnitude relationship with the output voltage from the detector in a state where the work cloth completely blocks the detector or a state where the work cloth is not present is determined based on a comparison result of the comparison means, and the reversal is determined. When this occurs, the indexing means determines the output voltage of the reference voltage changing means at that time, and the appropriate output voltage calculating means reverses the magnitude relationship with respect to the output voltage of the reference voltage changing means determined by the indexing means. The command data indicating another output voltage of the previous reference voltage changing means that differs by a predetermined margin is calculated, and the output of the reference voltage changing means calculated by the appropriate output voltage calculating means is stored in the storage means. The command data indicating the voltage is stored, and during a work cloth detection operation, the detection control means reads the command data from the storage means and applies it to the reference voltage changing means, and the output voltage of the reference voltage changing means is adjusted based on the data. , the comparison means compares the output voltage from the detector, and the presence or absence of the work cloth is detected based on the comparison result.

Therefore, there is no need for the operator to readjust the detection level of the detector when the shape (thickness) or material of the work cloth changes as in the past, which reduces the burden on the operator and prevents the detector from aging. It has the effect of being able to respond to changes. Furthermore, since the margin is set by the appropriate output voltage calculation means, it is possible to automatically set the optimum detection level that will not malfunction due to noise or the like, which is a very practical effect.

[Brief explanation of drawings]

Fig. 1 is an electrical block circuit diagram of a work cloth detection device embodying the present invention, Fig. 2 is a side cross-sectional view of the main part showing how the detector is installed, and Fig. 3 is the storage contents of a readable and writable memory. Figure 4 showing
The figure is a flowchart of the central processing unit, and FIG. 5 is a timing diagram. First and second cloth end detectors...1, 2, 1st
~4th cloth side edge detector...3-6, Work cloth guide device...7, Work cloth...9, 10, Pulse oscillator...
13, Comparator...16, AND circuit...1
7. Octal counter...18, Decimal counter...2
0, first and second flip-flop circuits...1
9, 21, central processing unit...22, readable and writable memory...24, D-A converter...27, microcomputer...MC, analog switch...SW1 to SW6.

Claims (1)

[Claims] 1. A detector that detects the presence of a work cloth and generates a detected output voltage; a reference voltage source that generates a predetermined output voltage; an output voltage from the reference voltage source and the detection A work cloth detection device comprising a comparison means for comparing the magnitude with an output voltage from an output voltage source, the work cloth detection device comprising: a reference voltage changing means capable of changing the output voltage of the reference voltage source; and a work cloth detection operation of the detection device. a reference voltage change control means that is enabled in advance and gives a change command to the reference voltage change means to increase or decrease the output voltage of the reference voltage change means stepwise in a predetermined order; The output voltage of the reference voltage changing means, which is sequentially increased or decreased based on the change command from the change control means, and the voltage from the detector in a state in which the work cloth completely blocks the detector or in a state in which the work cloth does not exist. determining means for determining whether the magnitude relationship with the output voltage of the reference voltage is reversed based on the comparison result of the comparing means; and determining the output voltage of the reference voltage changing means when the magnitude relationship is reversed based on the determination result of the determining means. and another output voltage of the reference voltage changing means before the magnitude relationship is reversed by a predetermined margin with respect to the output voltage of the reference voltage changing means indexed by the indexing means. Appropriate output voltage calculation means for calculating command data indicating different output voltages; Storage means for storing the command data indicating the output voltage of the reference voltage changing means calculated by the appropriate output voltage calculation means; and Storage means for the storage means. reads out the command data from and supplies it to the reference voltage changing means, causes the comparing means to compare the output voltage of the reference voltage changing means based on the data with the output voltage from the detector, and processes the data based on the comparison result. 1. A work cloth detection device comprising: detection control means for detecting the presence or absence of cloth.