JPS6238075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display circuit for an arc welding machine, which is a simplified display circuit for displaying current and voltage in an arc welding machine.

Conventionally, a display circuit of this type as shown in FIG. 1 has been known. That is, in the figure,
Reference numeral 1 denotes an oscillation circuit which outputs two types of 8-bit outputs, and outputs them to a first counter 2 and a second counter 3, respectively. The outputs of the first counter 2 and the second counter 3 are input to a first D/A converter (digital-to-analog converter) 4 and a second D/A converter 5, respectively.
The analog output of the A converter 4 and other arc voltages are input to the first voltage comparator 6, and the second
The analog output of the D/A converter 5 and other arc currents are input to a second voltage comparator 7. Further, the first counter 2 and the second counter 3 have reset terminals R _{1 and 3} respectively.
_R2 is installed, the outputs of the oscillation circuit 1 are connected alternately, and when a low level reset input is input to the reset terminals _R1 and _R2 , the first counter 2, the second counter 3 and the first D/A Converter 4 and 2nd
All outputs of the D/A converter 5 become 0.

8 is the third oscillator when the output of the oscillation circuit 1 is input.
The counter has a 4-bit output, and the other output of the oscillation circuit 1 is input to the reset terminal _R3 .

A fourth counter 9 receives the output of the oscillation circuit 1, has a 4-bit output, and inputs the output of the oscillation circuit 1 to the reset terminal _R4 . 10 is a first register which takes the 4-bit output of the third counter 8 as an input and the output of the first voltage comparator 6 as a set input; 11 has the 4-bit output of the fourth counter 9 as an input; 12 is a first decoder which takes the set 4-bit output of the first register 10 as input and converts it into a 7-bit output; 13 14 is a second decoder for inputting the 4-bit output set in the second register 11 and converting it into a 7-bit output; 14 is the first decoder 12;
The first segment consists of 7 segments with the output of
The LED light emitting display 15 is a second LED light-emitting display consisting of 7 segments that receives the output of the second decoder 13 as an input.
It is an LED light-emitting indicator.

However, in the display circuit configured as described above, when arc voltage and arc current are generated due to the start of welding, the output of the oscillation circuit 1 becomes the first
The signal is input to the counter 2 and the second counter 3, and the number of oscillation pulses is counted, and the output is converted into a binary number and becomes an 8-bit output. Here, a in FIG. 2 represents the input to the first and second counters 2 and 3;
Figure 2 b, c, d, and e show the output up to the 4th bit, and this 8-bit output is input to the first and second D/A converters 4 and 5, and is shown in Figure 3. It is converted to an analog value as shown.

In FIG. 3, the minimum dividing unit of the analog value is the first and second counters 2 and 3 shown in FIG.
These outputs are input to first and second voltage comparators 6, 7, and are compared with the values of arc voltage V and arc current I.

Then, when the analog output of the first or second D/A converter 4 or 5 becomes larger than the arc voltage V or the arc current I, respectively, the first or second voltage comparator 6 or 7 as shown in FIG. Produces the output as shown.

In FIG. 4, f is the output of the D/A converter 4 or 5, g is the arc voltage V or arc current I,
h is the output of voltage comparator 6 or 7. On the other hand, the output of the oscillation circuit 1 is also input to the third and fourth counters 8 and 9, and the oscillation pulses are counted. Here, the oscillation pulses are counted from 0 and a 4-bit output is output in binary, and the count number is 0.
9, when the output from the voltage comparator 6 or 7 is input to the set input of the first or second register 10, respectively, the contents of the 4-bit output of the counter 8 or 9 are input to the register 10 or 11, respectively. is sent to the output of

Note that the inputs to the above registers 10 and 11 are read and output only when the input signal to the set input rises from low level to high level, and the 4-bit output of the above registers 10 or 11 are respectively input to the first decoder 12 or the second decoder 13 and converted into a 7-bit signal, and the first or second LED light emitting indicators 14, 15 respectively indicate the arc voltage V or the arc current I. can be displayed. Figure 5 shows LED
This shows the operation of the light-emitting indicators 14 and 15, and displays predetermined numbers.

Note that the other outputs of the oscillation circuit 1 are oscillation pulses with a much lower frequency than the output. and first, second, third, and fourth counters 2,
3, 8, 9 are reset terminals R ₁ , R ₂ , R ₃ , respectively.
By inputting the output of the oscillation circuit 1 to _R4 , all the counter outputs become 0 as shown in FIG. 6 when the output is at a low level. In Fig. 6, l is the output of the oscillation circuit 1, f of m is the output of the D/A converter, g is the value of the arc voltage V and arc current I, n is the output of the voltage comparator, and P is the output of each counter. This is the output of the first bit. Here, the number of pulses within _T2 of P matches the value of arc voltage V or arc current I.
_T1 is the reset period of each counter.

In addition, in this explanation, an example is shown in which both the arc voltage and the arc current are accurately displayed as a single digit display from 0 to 9, but the basic circuit configuration does not change in any way for values beyond that, so the explanation will be continued. is omitted.

However, as mentioned above, in the conventional display circuit, two counters, one voltage comparator, and one D/A converter are required for displaying the arc voltage and arc current, which increases component cost and also increases the cost for mutual communication. Since the number of wirings increases, the scale becomes relatively large, and the noise resistance is also poor in terms of performance.

The present invention has been made to solve the above-mentioned conventional drawbacks, and uses a counter, a voltage comparator, and a D/A converter in common to display arc voltage and arc current. By using it alternately for arc voltage display and arc current display, it is possible to reduce the number of parts and simplify the circuit, including wiring, making it economical.
The present invention provides a display circuit for an arc welding machine that also has improved noise resistance.

Hereinafter, embodiments according to the present invention will be described in detail based on FIG. In the figures, parts corresponding to those in the conventional structure are given the same reference numerals and their explanations will be omitted.
Reference numeral 81 in FIG. 7 is a divider that receives the signal input from the output of the first D/A converter 6. This divider 81 is provided with an output Q, which has a phase relationship completely opposite to that of the output Q. Yes, these outputs change at the rising edge of the signal input. 82 is a first selector, one of its inputs is connected to the output of the divider 81,
A signal of arc voltage V is input to the other input. The output of the first selector 82 is connected to the input of the first voltage comparator 6. 83 is a second selector, one of its inputs is connected to the output Q of the divider 81, and the other input receives the signal of the arc current I. The output of the second selector 83 is
The input of the first voltage comparator 6 is connected to the same point as the output of the first selector 82 .

The operation of the circuit described above will be explained below. First, when arc voltage and arc current are generated by the start of welding, the output of the generation circuit 1 is input to the first counter 2, and the number of oscillation pulses is counted. A part of the output of this counter 2 is
As shown in the figure, the signal is input to the first D/A converter 4 and converted into an analog value. The minimum dividing unit of the analog value is the output of the first bit shown in FIG. 2b. The output of the first D/A converter 4 is input to the first voltage comparator 6, and the output of the first selector 82 or the second selector 8
It is compared with the output of 3. One of the first and second selectors 82 and 83 is selected to operate according to the output Q of the divider 81. And only for the selected one, another input,
That is, the arc voltage V or the arc current I is input to the voltage comparator 6 as its output.
That is, to explain the state in which the first selector 82 is selected, when the analog output of the first D/A converter 4 becomes larger than the arc voltage V, the first voltage comparator 6 outputs an output at that moment.

Figure 4 shows this situation, where f is D/A
The output of the converter 4, g is the arc voltage V, and h is the output of the voltage comparator 6.

In response to the output of the voltage comparator 6, the output of the divider 81 changes. In other words, the output is high →
The output Q changes from low to high. Therefore, the first register 10 has its set input low →
Due to the change to high, the first register 10 can read and output its input. At this time,
The input read into the first register 10 is
This is the number of oscillation pulses output from the oscillation circuit 1 counted by the counter 8. In this way the third
The counter 8 counts the input oscillation pulses from 0 and outputs a 4-bit binary output. The 4-bit output of the register 10 is input to the first decoder 12, where it is converted into a 7-bit signal, and the first LED display 14 can display the arc voltage V as shown in FIG. can.

Further, the other outputs of the oscillation circuit 1 are oscillation pulses having a much lower frequency than the output. By inputting the output of the oscillation circuit 1 to the reset terminal R of each of the first and third counters 2 and 8, the output of each counter becomes 0 when the output is at a low level.

Next, as the first voltage comparator 6 outputs an output, the output of the divider 81 changes and the first voltage comparator 6 outputs an output.
The selector 82 stops operating, and the second selector 83
becomes operational, and the arc current I can now be displayed using exactly the same principle as the display of the arc voltage V described above. That is, the arc voltage V and arc current I are read and displayed alternately, and the previous read value continues to be displayed until the next reading timing.

By the way, in general, in arc welding machines, the ammeter and voltmeter are often installed on the same panel, so it is not possible for the operator to read both at the same time, but rather they must read one at a time. There is no problem even if the reading timing of the arc voltage V and the arc current I to the register is alternated as in the present invention.

As described above in detail, the display circuit of the arc welding machine according to the present invention has a part of the counter, the voltage comparator, and the D/A converter depending on the arc voltage.
It is shared for arc current display, and at that time, it is time-divided and used alternately for arc voltage display and arc current display, which reduces component costs and reduces wiring between components. , the circuit configuration is simplified, the cost can be reduced, and the noise resistance performance can be improved.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a display circuit showing a conventional example, Fig. 2 is an explanatory diagram showing the input/output waveforms of the counter, Fig. 3 is an explanatory diagram showing the output waveforms of the D/A converter, and Fig. 4 is an explanatory diagram showing the output waveforms of the D/A converter. An explanatory diagram of the operation of the voltage comparator, Fig. 5 is an explanatory diagram showing the operating state of the LED light emitting display, Fig. 6 is an explanatory diagram showing the display principle, and Fig. 7 is a configuration diagram of a display circuit showing an embodiment according to the present invention. It is. 1...Oscillation circuit, 2...First counter, 4...
First D/A converter, 6... First voltage comparator, 8... Third counter, 10... First register, 11... Second register, 12... First decoder, 13... ...Second decoder, 14...
...First LED light emitting indicator, 15...Second LED
Light emitting display, 81... Divider, 82... First selector, 83... Second selector.

Claims (1)

[Claims] 1. In the display circuit of the arc welding machine that digitally displays the arc voltage and arc current values detected from the arc welding machine, the output of one D/A converter is time-divided and the voltage is compared with the arc voltage value and the arc current value, It also has one counter for each digit to count the number of oscillation pulses corresponding to the arc voltage value and arc current value, and one register for each digit to stably display the counted value. A display circuit for an arc welding machine, characterized in that the functions of the counter and register described above are also used in a time-division manner to display arc voltage values and arc current values.