JPH0498161A - Polarity detection method for aluminum electrolytic capacitor - Google Patents

Abstract

PURPOSE:To discriminate polarity in a short time regardless of a static electrostatic capacity and connection condition, by detecting electric potential between a case and terminals at the time of both terminals being impressed with forward voltage and backward voltage, and discriminating the polarity of a terminal from its potential difference. CONSTITUTION:First, measuring terminals 10, 9 and 11 are respectively connected to a positive electrode terminal 3, a negative electrode terminal 4 and a case 2, and potential En between the terminal 4 and the case 2 is measured by means of a voltmeter 12. Next, changing is done so that the terminal 10 is connected to the terminal 4 and the terminal 9 is connected to the terminal 3, and potential En between the terminal 3 and the case 2 is measured by means of the meter 12. And, polarity is discriminated on the basis of the difference between the potential at the time of forward voltage impression and the potential at the time of backward voltage impression. As a result, even in a large static capacity aluminum electrolytic capacitor polarity can be discriminated in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aluminum electrolytic capacitor polarity detection method for determining whether or not the polarity of the aluminum electrolytic capacitor is correctly mounted on a printed circuit board.

(Prior art) Conventionally, this type of technology has been known to determine the polarity by comparing the value of the current flowing when a constant voltage in the forward and reverse directions is applied between both terminals of an aluminum electrolytic capacitor. It is being

It is also known that the polarity can be determined by human visual inspection.

(Problem to be solved by the invention) Among the problems mentioned in the conventional technology, the former has the problem that it takes time to measure and detect a capacitor with a large capacitance, and When configuring a circuit with two aluminum electrolytic capacitors that have a considerable difference in capacitance and their respective terminals shorted, or when a small impedance element is connected between one terminal of each and the other If a circuit is configured with the terminals shorted, the capacitor with smaller capacitance will be absorbed by the capacitor with larger capacitance, making it difficult to determine the polarity of the capacitor with smaller capacitance. The problem was that it was impossible.

Also, in the latter case, there is a possibility that mistakes may occur.
It also had the problem of being difficult to automate.

The present invention was made in order to solve these problems with the conventional technology, and its purpose is to be able to determine polarity in a short time regardless of the size of capacitance or the connection state. This paper attempts to provide a method for detecting the polarity of aluminum electrolytic capacitors.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides the case of the aluminum electrolytic capacitor and the The electric potential between the terminals is detected, and the polarity of the terminal is determined from the difference in electric potential.

Further, when a voltage is applied between both terminals of the aluminum electrolytic capacitor, a potential between the case of the aluminum electrolytic capacitor and the terminal is detected, and the polarity of the terminal is determined by comparing the potential with a predetermined value. You can also do that.

(Function) When a forward voltage and a reverse voltage are applied to both terminals of an aluminum electrolytic capacitor, a difference occurs in the magnitude of the potential between the case of the aluminum electrolytic capacitor and the terminals, and the polarity of the terminals can be determined from that potential difference.

Furthermore, the polarity of the terminal can be determined by comparing the magnitude of the potential between the case and the terminal of the aluminum electrolytic capacitor with a predetermined value when a voltage is applied between both terminals of the aluminum electrolytic capacitor.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a measurement circuit diagram for carrying out the polarity detection method for an aluminum electrolytic capacitor according to the present invention, and FIG. 2 is an equivalent circuit when focusing on the case of an aluminum electrolytic capacitor.

The aluminum electrolytic capacitor 1 can be represented by an equivalent circuit as shown in FIG. When a voltage is applied between the electrode terminals 3 and 4 and the cathode terminal 4, a current also flows between each electrode terminal 3, 4 and the case 2.

The anode made of aluminum foil to which the anode terminal 3 is connected is coated with a dielectric material on the aluminum surface, while the cathode made of aluminum foil to which the universal fault terminal 4 is connected is coated with a dielectric material. is not formed, it is considered that there is a difference in the magnitude R, , R, of the impedance 5.6 between the anode terminal 3 and the case 2, and between the cathode terminal 4 and the case 2.

Therefore, the voltage divided by the impedance 5 between the anode terminal 3 and the case 2 and the impedance 6 between the cathode terminal 4 and the case 2 is measured by a measuring circuit as shown in FIG. The measurement circuit connects a constant voltage measurement power supply 7 and a resistor 8 in series, and provides a measurement terminal 9 on the negative side of the measurement power supply 7 and a measurement terminal 10 on one end of the resistance 8. A voltmeter 12 is provided to measure the voltage between the measurement terminals 11.

First, when the measurement terminal 10 is connected to the anode terminal 3, the measurement terminal 9 is connected to the cathode terminal 4, and the measurement terminal 11 is connected to the case 2, a forward voltage is applied to the aluminum electrolytic capacitor 1. The voltmeter 12 measures the potential En due to the impedance 6 between the cathode terminal 4 and the case 2.

Next, when the measurement terminal 10 is replaced with the cathode terminal 4 and the measurement terminal 9 is replaced with the anode terminal 3, a reverse voltage is applied to the aluminum electrolytic capacitor 1, and the voltmeter 12 measures the anode terminal 3 and the case. Potential En due to impedance 5 between 2
will be measured.

Changes over time in the potential E when a forward voltage is applied and the potential En when a reverse voltage is applied, measured as described above, are measured using a blower [...] as shown in the graph shown in Figure 3. becomes.

The graph of the measurement results shown in FIG. 3 is based on the measurement power supply 7.
voltage value Em-20 [1 mV, resistance value Rf of resistor 8 = 1
When Ω is 0.

From the measurement results shown in Figure 3, the potential E when a forward voltage is applied to the aluminum electrolytic capacitor 1. is the potential E of the opposite voltage applied. Obviously lower. This indicates that the value Rn of the impedance 6 between the cathode terminal 4 and the case 2 is smaller than the value Rp of the impedance 5 between the anode terminal 3 and the case 2.

Therefore, the measurement terminals 9, 10.11 are connected to each electrode terminal 3.4 of the aluminum electrolytic capacitor 1 and the case 2, and the difference in potential E1 measured twice by the voltmeter 12 is measured using a comparator or the like. It can be determined whether the terminal connected to the measurement terminal 9 when the smaller potential En is measured, the cathode terminal 4, the other terminal, or the anode terminal 3.

In addition, as can be seen from the graph of the measurement results shown in Figure 3, it is better to measure the potential En immediately after applying the voltage values E, , n of the measurement power source 7, which shortens the measurement time. can be achieved.

Also, as shown in FIG. 3, the potential E when a forward voltage is applied to the aluminum electrolytic capacitor 1. and the potential E when a reverse voltage is applied. They can be clearly distinguished as the potential En when a forward voltage is applied and the potential E when a reverse voltage is applied. The intermediate potential between the two that can be determined is set in advance as a predetermined value, and the measurement terminals 9.10 are arbitrarily connected to each electrode terminal 3.4 of the aluminum electrolytic capacitor 1 regardless of whether they are in the order or in the reverse direction. , and then connect the measurement terminal 11 to the case 2 and perform one measurement using the voltmeter 12 to obtain the measured potential E. If the value is lower than the predetermined value, it can be determined that the terminal of the aluminum electrolytic capacitor 1 connected to the measurement terminal 9 is the cathode terminal 4. - If the force measurement potential En is higher than a predetermined value, it can be determined that the terminal of the aluminum electrolytic capacitor 1 connected to the measurement terminal 9 is the anode terminal 3.

In addition, FIG. 4 shows the polarity detection method of an aluminum electrolytic capacitor according to the present invention.
er, an in-circuit tester).

Aluminum electrolytic capacitor 1 mounted on printed circuit board 20
The contact pins 22 and 23 of the ICT 21, which correspond to the measurement terminals 9 and 10, were brought into contact with the soldered terminals 3 and 4 of the ICT 21, and also installed on the attachment part 25 of the backup pin 24 of the ICT 21 via the bracket 26. When the contact pin 27 corresponding to the measurement terminal 11 is brought into contact with the case 2 of the aluminum electrolytic capacitor 1, the voltage corresponding to the voltage value E4 of the measurement type 7 is measured. 4.

The polarity of the power supply for measurement should be connected to both terminals 3 and 4 in accordance with the polarity when the aluminum electrolytic capacitor is correctly mounted on the printed circuit board. Therefore, the measured potential En
If it is determined that the potential is lower than the reference potential, it can be determined that the aluminum electrolytic capacitor is correctly mounted on the printed circuit board.

In this way, the method for detecting polarity of aluminum electrolytic capacitors can be applied by adding only a few improvements to conventional ICT.

(Effects of the Invention) As explained above, according to the present invention, the polarity can be determined in a short time even with an aluminum electrolytic capacitor having a high capacitance.

Furthermore, even when aluminum electrolytic capacitors are connected in parallel, the polarity of each can be determined.

[Brief explanation of the drawing]

Figure 1 is a measurement circuit diagram for implementing the polarity detection method for aluminum electrolytic capacitors according to the present invention, Figure 2 is an equivalent circuit diagram focusing on the case of an aluminum electrolytic capacitor, and Figure 3 is a graph of measurement results. , FIG. 4 is a schematic explanatory diagram in which the polarity detection method of an aluminum electrolytic capacitor according to the present invention is applied to ICT. 1... Aluminum electrolytic capacitor, 2... Case, 3...
...Anode terminal, 4...Cathode terminal, 7...Measurement power supply, EIT...Measurement potential.

Claims (2)

[Claims] (1) In a method for determining whether an aluminum electrolytic capacitor is mounted on a printed circuit board with correct polarity, the aluminum electrolytic capacitor 1. A method for detecting polarity of an aluminum electrolytic capacitor, comprising detecting a potential between a case of the electrolytic capacitor and the terminal, and determining the polarity of the terminal from the difference in potential. (2) In a method for determining whether an aluminum electrolytic capacitor is mounted on a printed circuit board with correct polarity, when a voltage is applied between both terminals of the aluminum electrolytic capacitor,
A method for detecting polarity of an aluminum electrolytic capacitor, characterized in that the polarity of the terminal is determined by detecting the potential between the case of the aluminum electrolytic capacitor and the terminal, and comparing the potential with a predetermined value.