JPH01250076A - Detector for overcurrent element - Google Patents

Abstract

PURPOSE:To eliminate a disconnection of the wiring for an electric power source by making the current between two points of a current wiring to be 0mA with the current supplied from outside so that a potential difference between the two points is made to be 0muV and detecting an overcurrent element in the manner of measuring a power source current in case the two points are electrically separated. CONSTITUTION:Voltage detecting terminals 1, 2 are connected respectively to the two points of the power source wiring for a measuring object, a current terminal 3 is connected to the same point as that of the terminal 2, a current 4 is connected to a ground of the measuring object and the potential difference between the two points of the power source wiring for the measuring object is made to be 0muV. The current is made to be 0mA and the two points are electrically separated. then plural points on the power source wiring are electrically separated in order, and the power source current at that time is measured. The overcurrent element is thereby detected and the disconnection of the power source wiring is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the inspection and repair of circuit boards, etc., on which multiple elements are mounted. The present invention relates to a detection device for detecting flowing elements.

[Summary of the invention]

In the overcurrent element detection device, this invention supplies a current from the outside so that the potential difference between the two points of the power supply wiring becomes 0μ■, the current between the two points becomes OmA, and electrically connects the two points. The overcurrent element is detected by measuring the power supply current when separated.

[Conventional technology]

Conventionally, as a method of detecting an element with an excessive power supply current among a plurality of elements connected to the same power supply, the elements are removed one by one until the power supply current returns to normal.

Alternatively, methods such as sequentially cutting the power supply wiring at multiple locations have been used.

[Problem to be solved by the invention]

However, the conventional method of removing elements one by one has the disadvantage that if the element is an integrated circuit, there are many terminals and it takes a lot of time to remove it, and furthermore, if the removed element is normal, it requires work to reinstall it. was there.

In addition, the conventional method of sequentially cutting multiple locations of power supply wiring is as follows:
There was a drawback that the wiring board was damaged and had to be repaired later.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a power supply current abnormal element detection device that detects an element with excessive power supply current from among a plurality of elements connected to the same power supply, which includes a pair of voltage detection terminals; It consists of a pair of current terminals, a resistor, an operational amplifier, and two diodes. One of the voltage detection terminals is connected to the non-inverting input terminal of the operational amplifier, and the other voltage detection terminal is connected to one of the resistors. the other of the resistors is connected to the inverting input terminal of the operational amplifier, the anode of the first diode is connected to the inverting input terminal of the operational amplifier, the cathode is connected to the output terminal of the operational amplifier, and the second diode is connected to the inverting input terminal of the operational amplifier; The anode of is connected to the output terminal of the operational amplifier, the cathode is connected to one current terminal, and the other current terminal is connected to the ground, and the current is applied to the current terminal so that the potential difference between the voltage detection terminals is 0μ■. We decided to supply the following.

[Effect]

A pair of voltage detection terminals of the power supply current abnormal element detection device configured as described above are brought into contact with two points of the power supply wiring to be measured, respectively, and one of the current terminals is brought into contact with the same point as one of the voltage measurement terminals. , the other current terminal is connected to the ground of the object to be measured, and a current is supplied to the current terminal so that the potential difference between the two points of the power supply wiring becomes 0 μ■. Since the potential difference between two points of the power supply wiring is OμV, no current flows and it is possible to electrically isolate them. By electrically separating multiple points of the power supply wiring one after another and measuring the power supply current at that time, the power supply is determined. This makes it possible to detect elements with excessive current.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing an example of an overcurrent element detection device of the present invention. In FIG. 1, voltage detection terminal 1 is connected to the non-inverting input terminal of operational amplifier 6, voltage detection terminal 2 is connected to one side of resistor 5, and the other side of resistor 5 is connected to the inverting input terminal of operational amplifier 6. The anode of the first diode 7 is connected to the inverting input terminal of the operational amplifier 6, the cathode is connected to the output terminal of the operational amplifier 6, and the anode of the second diode 8 is connected to the output terminal of the operational amplifier 6. However, the cathode is connected to the current terminal 3, and the current terminal 4 is connected to the ground.

In such a configuration, voltage detection terminals 1 and 2 are brought into contact with two points of the power supply wiring to be measured, current terminal 3 is brought into contact with the same point as voltage detection terminal 2, and current terminal 4 is connected to the ground of the measurement object. By connecting and setting the potential difference between the two points of the power supply wiring to be measured to 0μ, the current becomes OmA, electrically separating the two points. The second diode 8 prevents current from flowing into the current terminal 3 when the potential of the voltage detection terminal 1 is lower than the potential of the voltage detection terminal 2.
The first diode 7 prevents the output of the operational amplifier 6 from saturating negatively.

FIG. 2 is an explanatory configuration diagram showing an example of detection according to the present invention. In FIG. 2, reference numeral 9 denotes an overcurrent element detection device according to the present invention, and ICs 16 to 18 are used as the negative terminal of a power supply 10, each ground terminal is connected to the ground, and the positive terminal is connected to one side of the ammeter 11. The other terminal is connected to the current terminals of ICs 16 to 18 by wiring 12. Voltage detection terminal 1 is in contact with point 13 on wiring 12, and both voltage detection terminal 2 and current terminal 3 are in contact with point 14 on wiring 12. The current terminal 4 is connected to ground.

In such a configuration, since the potential difference between the two points 13 and 14 on the wiring 12 is Oμ■, no current flows, and the ammeter 11 indicates the value of the current flowing only from the point 13 on the wiring 12 to the IC 16. Therefore, points 13 and 14 on wiring 12 can be electrically isolated. Similarly, in FIG. 2, if voltage detection terminal 1 is brought into contact with point 14 on wiring fi 12, and voltage detection terminal 2 and current terminal 3 are brought into contact with point 15 on wiring 12, ammeter 11 will be connected to IC 16. It shows the current value flowing through the IC 17 and can electrically isolate points 14 and 15 on the wiring board A12.

In this way, any part of the power supply wiring is isolated and the power supply current at that time is measured with the ammeter 11, the part where abnormal current is flowing is confirmed, and an overcurrent element is detected.

For example, in Fig. 2, if the wiring 12 is a printed circuit board wiring pattern, is made of copper with a thickness of 35 μm and a width of 2 mm, and the length between points 13 and 14 on the wiring 12 is 201 m, the resistance value of the copper is Since the volume resistivity is 1.69×10 −'Ω·m, it is approximately 4.8 mΩ, and a potential difference of 48 μι is generated at 10 mA. Voltage detection terminal 1 is brought into contact with point 13 on wiring 12, voltage detection terminal 2 and current terminal 3 are brought into contact with point 14 on wiring 12, and the potential difference between points 13 and 14 on wiring 12 is set to ±1μ.
When the current is set to be less than or equal to v, the current can be suppressed to less than about ±0.21 mA. Ammeter 11 indicates the sum of the current flowing through IC 16 and the current between points 13 and 14 on wiring 12, so IC1
6 current can be measured with an error of ±0.21 mA or less, and IC1
It is possible to detect whether the current in No. 6 is abnormal.

〔Effect of the invention〕

As explained above, this invention makes it possible to electrically separate the current between two points of the power supply wiring by approximately 0mA, so that the current between two points of the power supply wiring can be electrically separated. When detecting an abnormal element, there is an advantage that there is no need to cut off the power supply wiring or remove the elements one by one.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a power supply current abnormal element detection device of the present invention. FIG. 2 is an explanatory configuration diagram showing a measurement example according to the present invention. 1.2... Voltage detection terminal 3.4... Current terminal 5... Resistor 6... Operational amplifier 7... First diode 8... First Diode 9 of 2... Overcurrent element detection device 10... DC power supply 11... Ammeter 12... Wiring 13 to 15... Point 16 on wiring 12 ~18・ ・ ・ IC Applicant: Seiko Electronics Co., Ltd. Figure 1 [C Detection example using Kihachi gF41 Figure 2: Configuration diagram for explanation

Claims (1)

[Claims] In an overcurrent element detection device that detects an element with excessive power supply current from among multiple elements connected to the same power supply, one of a pair of voltage detection terminals is connected to a non-inverting input terminal of an operational amplifier. , the other is connected to one of the resistors, the other of the resistor and the anode of the first diode are connected to the inverting input terminal of the operational amplifier, and the cathode of the first diode and the anode of the second diode are connected to the inverting input terminal of the operational amplifier. The second diode is connected to the output terminal of the operational amplifier, the cathode of the second diode is connected to one of the pair of current terminals, the other current terminal is connected to ground, and the potential difference between the pair of voltage detection terminals is 0 μV. A detection device for an overcurrent element, characterized in that the device is configured to supply a current to the pair of current terminals so that the current is supplied to the pair of current terminals.