JPH05180891A - Automatic tester for printed board - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an automatic tester for a printed circuit board including a rotary variable resistor, and changes the resistance value for the operation test of the printed circuit board without using a large-scale device such as a robot. It is an object of the present invention to provide a testing machine that automatically tests the response of the internal circuit when it is activated. In an automatic tester for a printed circuit board 1 including a rotary variable resistor 3 and an internal circuit 2 that outputs a signal according to the operation of the resistor 3, the rotary variable resistor 3 is connected in parallel to a variable resistor. A programmable resistor 10 for changing the combined resistance value without operating the device 3 and a measuring means 11 for automatically measuring the output signal from the internal circuit 2 are provided, and the output signal when the combined resistance is changed is provided. It is configured by being measured by the measuring means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tester for a printed circuit board including a rotary variable resistor. Since electronic devices including microcomputers are remarkably improved, it is extremely important for manufacturers to supply electronic device products at low cost in a timely manner. Therefore, there is an increasing need for automatic testing of printed circuit boards, which are the main components of equipment.

[0002]

2. Description of the Related Art As computer systems such as microcomputers become more sophisticated, it is necessary to continue to improve electronic devices for downsizing of devices. Therefore, it has become more and more necessary to rationalize the test process after manufacturing a printed circuit board, which is a main component of electronic device products. However, the operator always touched the conventional test process. That is, a rotary variable resistor is often mounted in a printed circuit board. If the printed circuit board is for LCD (liquid crystal display) control and printer control, a plurality of variable resistors are required. A circuit called a so-called internal circuit is mounted on the printed circuit board, and the test process proceeds only by the processing of the operator.

FIG. 5 is a schematic view showing a top surface of a printed circuit board and a partial circuit configuration as a conventional technique. In FIG. 5, 1 is a printed circuit board, 2 is an internal circuit as a whole, 3 is a rotary variable resistor for LCD density adjustment, 4 is a rotary variable resistor for printer density adjustment, and 5 is an LCD interface. A connector, 6 is a printer interface connector, 7 is an internal control circuit for sending display data to be displayed on the LCD screen, and print data to be printed on the printer to the apparatus via the respective connectors 5, 6. Is an LCD screen control unit, and 9 is a printer control unit.

The internal circuit 2 includes an internal control circuit 7 and a control unit 8,
In addition to 9, a central processing unit and a memory are built in.
A printed circuit board on which a large number of these electronic components are mounted is operated by operating the rotary variable resistors 2 and 3 to test whether the LCD screen density control and the printer print density control can be performed as planned. Not only can the status of the devices 2 and 3 be checked, but the operation of the entire device including the internal circuit 2, LCD, and printer can be checked. Therefore, in the actual test, the printed circuit board in the actual device is removed, the printed circuit board under test is mounted instead, and the device is operated, and the operator judges the response while operating the variable resistor one by one. ..

[0005]

The testing means for the conventional device has a drawback that the intervention of the operator is absolutely necessary, and even if the test result is reliable, the operator is hung up for a long time.

An object of the present invention is to remedy the above-mentioned drawbacks and to respond to the internal circuit when the resistance value is changed without using a large-scale device such as a robot for the above-mentioned operation test of the printed circuit board. The purpose is to provide a testing machine for automatically testing.

[0007]

FIG. 1 is a diagram showing the principle configuration of the present invention. In FIG. 1, 1 is a printed circuit board under test, 2 is an internal circuit, 3 is a rotary variable resistor, 10 is a programmable resistor, and 11 is a measuring means.

In the automatic tester for the printed circuit board 1 including the rotary variable resistor 3 and the internal circuit 2 for outputting a signal according to the operation of the resistor 3, the present invention has the following constitution.
That is, the variable resistor 3 is connected in parallel to the rotary variable resistor 3.
A programmable resistance 10 for changing the combined resistance value without operating the and a measuring means 11 for automatically measuring the output signal from the internal circuit 2 are provided, and the output signal when the combined resistance is changed is measured. It is configured by measuring by means 11.

[0009]

In the automatic tester according to the present invention, the combined resistance value of the programmable resistor 10 and the rotary variable resistor 3 is changed by opening / closing the switch as appropriate without operating the operation knob of the variable resistor 3. It can be done. When the combined resistance value is the predetermined resistance value, the output signal of the internal circuit 2 is measured by the measuring means 11. Depending on whether or not the measured value is compared with a predetermined value, the variable resistor 3
Alternatively, it is possible to check whether the internal circuit 2 is abnormal. Next, by repeating the state check when the combined resistance value is changed, the automatic test of the device can be easily performed.

[0010]

FIG. 2 is a partial cross-sectional view showing an embodiment of the present invention. In FIG. 2, 10 is a programmable resistor,
11 is a voltage measuring circuit of a part of the measuring means, 12 is a casing of the automatic testing machine, 13-1 and 13-2 are positioning pins, which are provided on the fixed plate 14 of the printed circuit board, and each terminal of the printed circuit board 1 It is inserted into a recessed hole provided in the printed board 1 so as to be accurately positioned with respect to the tester housing 12. In addition, the fixed plate 14 is provided with a probe pin, which is connected to each terminal on the back side of the printed circuit board, and the terminal is connected to the measurement circuit in the tester. A pressing tool 15 is located outside the printed circuit board 1 to be tested, and presses the printed circuit board 1 toward the tester housing 12 so as to maintain good contact between the terminals of the printed circuit board 1 and the probe pins. There is.

The printed circuit board 1 to be tested is brought into contact with an accurate position on the back surface side of the surface on which the components are mounted, via the fixing plate 14 and the tester housing 12 and the position pins 13-1 and 13-2. Then, the programmable resistor 10 is variably operated. FIG. 3 is a diagram showing a configuration example of the programmable resistor. In FIG. 3, 8 is an LCD control unit, 10 is a programmable resistor, and 10 is a programmable resistor.
-11,10-21 to 10-n1 is a switch, 10-21,10-32 to 10-n2
Is a resistance element connected in series with the switch, 31 is a rotary variable resistor, 32 and 33 are resistance elements connected in series with the variable resistor 31, 34 is an operating power supply, and 35 is ground. VR indicates a connection point between the programmable resistor 10 and the variable resistor 31, and the combined resistance value between the VR and the ground 35 can be changed programmable by turning on / off the switches 10-11 to 10-n1.

FIG. 3 shows a variable resistor 31 having a maximum resistance value of 1 kΩ.
2 is a variable resistance circuit showing a case where a plurality of parallel resistors are connected in parallel. In FIG. 3, the resistance elements 32 and 33 are both 1
It has a resistance value of kΩ and the voltage of the power supply 35 is set to 15V.
No variable resistor is connected, only variable resistor is 0Ω
To 1 kΩ, the voltage at the point VR can be changed from 5V to 10V. Now, if the variable resistor is set to 0Ω (closer to the ground) and the switch is turned on so that the programmable resistance 1kΩ is connected in parallel, the combined resistance value becomes “0”, so the voltage at the point VR is 5V. Variable resistor 1k
If the switch is turned on so that Ω is connected in parallel with the programmable resistance 1 kΩ, the combined resistance value becomes 0.5 kΩ, so the voltage at the point VR is 6V. If the variable resistor is 1 kΩ and the programmable resistance is 0Ω, the combined resistance value is 0Ω, so the voltage at the point VR is 5V.

That is, the variable resistor 31 is fixed to 1 kΩ,
When the programmable resistance is changed from 0Ω to infinity,
The voltage at point VR changes from 5V to 10V and the variable state of the programmable resistance becomes similar to changing only the variable resistor. Therefore, if the output signal of the internal circuit when the voltage at the point VR is changed by the programmable resistor 10 is measured by, for example, a voltmeter in the voltage measuring circuit 11 of FIG. 2, the operation of the variable resistor / internal circuit can be checked.

FIG. 4 shows a simple example of a programmable resistor, which has a single resistance element 10-22. The resistance value of the programmable resistance is 0Ω and 1kΩ by the changeover switch.
Can be changed to and.

The measurement in the voltage measuring circuit 11 may be carried out by comparison measurement with an analog comparator (window comparator). Further, as the automatic tester according to the present invention, the printed circuit board under test is set at a predetermined position and pressed by the pressing plate, and the output value of the internal circuit is automatically measured by the measuring means each time the programmable resistance is changed. However, detailed description thereof will be omitted because well-known matters may be applied to all of the means.

[0016]

As described above, according to the present invention, it is not necessary for an operator to rotate the variable resistor of the printed circuit board under test one by one to check the output value at that time, and the output signal can be adjusted by adjusting the programmable resistance. Therefore, it is effective to realize an unmanned machine by simplifying the process and becoming an automatic tester.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

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

FIG. 3 is a diagram showing a configuration example of a programmable resistor.

FIG. 4 is a diagram showing a simple example of a programmable resistor.

FIG. 5 is a schematic top view of a printed circuit board.

[Explanation of symbols]

 1 Printed Circuit Board 2 Internal Circuit 3 Rotary Variable Resistor 10 Programmable Resistance 11 Measuring Means

Claims (2)

[Claims] 1. An automatic tester for a printed circuit board (1) including a rotary variable resistor (3) and an internal circuit (2) for outputting a signal according to the operation of the resistor (3), wherein Programmable resistor connected in parallel to the variable resistor (3) to change the combined resistance value without operating the variable resistor (3)
(10) and measuring means (11) for automatically measuring the output signal from the internal circuit (2), and measuring the output signal when the combined resistance is changed by the measuring means (11). A printed circuit board automatic tester characterized in that 2. The signal measuring means according to claim 1, further comprising a positioning pin projecting toward the printed circuit board between the signal measuring means and the printed circuit board, and a pressing tool for pressing the printed circuit board toward the signal measuring means on the outside of the printed circuit board. A printed circuit board automatic testing machine characterized by being provided.