JPH0743235U - Leakage detection circuit for electrolytic capacitors - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a leak detection circuit for an electrolytic capacitor used in a power supply device. The leaked electrolyte may cause defective insulation of peripheral circuits or electrical leakage. The purpose is to detect defects, heat generation, smoke emission, and ignition before they occur. Another object is to be able to detect liquid leakage of a plurality of scattered capacitors with a single detection circuit. [Structure] In the detection circuit for electrolyte that has leaked from the electrolytic capacitor, near the electrolytic capacitor to be detected,
It has a structure in which the detection electrodes are provided by a wiring pattern on the printed board where the electrolytic solution easily attaches or falls.
The leaking electrolyte from the capacitor is detected by this detection electrode.
It becomes the input signal of the leak voltage or the resistance change and is detected by the comparator section.

Description

[Detailed description of the device] [Industrial applications]

 The present invention relates to a circuit for detecting leakage of liquid from an electrolytic capacitor. Specifically, the present invention relates to a detection circuit for safety measures, which prevents leakage of liquid from an electrolytic capacitor to abnormal operation of peripheral circuits or to prevent smoke or ignition.

[0001]

[Prior art]

 Conventionally, there is no means for directly detecting the liquid leakage from the electrolytic capacitor. Instead, for abnormal heat generation due to electrolytic capacitor leakage, the electronic device as a whole can be shared with other heat sources and a temperature sensor, etc., can be installed at a position where it can be easily detected to prevent abnormal heat generation. Had detected. In other words, a detection method that focuses on abnormal heat generation is used to output an alarm or shut off the power output.

Even today, it cannot be said that the capacitor parts used in electronic circuits with severe temperature conditions can be used with peace of mind, and safety measures are still insufficient. In addition, there are many cases where product cost issues, high-density mounting, and miniaturization are prioritized, and safety measures and reliability considerations have not yet been established. In recent years, even in order to improve and secure the reliability of the system, there is an increasing demand to take measures for safety measures.

In an electronic device, the capacitor exposed to a high temperature environment rarely has a rise in internal pressure of the capacitor due to long-term operation or the like, or an internal short circuit due to insulation deterioration of an oxide film of an internal separator. , The sealing rubber part safety valve and the viscous electrolytic solution inside leak out from the lead wire, and the leaked electrolytic solution deposits and grows (migrates) to become a low resistance (several hundred ohms) and become a heat source. , Causing smoke and fire.

In addition, the sealed electrolytic solution evaporates or the electrolytic solution leaks out, resulting in insulation failure of peripheral circuits, causing electrical failure such as unstable operation, and secondary failure such as external device failure. It may cause a serious disaster and cause serious trouble to the entire system.

[0005]

[Problems to be solved by the device]

 The problem to be solved by this device is to detect the leaked electrolyte of the electrolytic capacitor before the electrical insulation of the peripheral control circuit causes electrical failure, heat generation, smoke generation, and ignition. With the goal. Another object of the present invention is to be able to detect the liquid leakage of a plurality of the capacitors scattered by one detection circuit.

[0006]

[Means for solving the problem]

 In the present invention, the above problem is solved by the following means. In the detection circuit of the leaked electrolytic solution generated by heat generation or the like from the electrolytic capacitor C1 of the power supply device, the detection electrode 11 is pattern-wired near the electrolytic capacitor C1 to be detected. The surface of this electrode pattern is made to be a detection electrode by exposing the electrode without resist treatment.

A means for directly detecting a leak voltage from the electrolytic solution 10 leaked from the capacitor is used, and a change in the detected voltage is used as an input signal to the comparator section 17. A detection circuit having means for detecting the change in the input signal voltage by the comparator section 17.

[0008] Further, in order to detect liquid leakage from the electrolytic capacitor, not to detect a leak voltage, but to provide two electrodes and to detect a change in resistance between the electrodes due to the electrolytic solution. ), An electrode structure in which the ground electrode 16 is arranged adjacent to the detection electrode 11 is added.

Since the bias voltage Vt is applied to the detection electrode 11 through the high resistance R1, a leak current is generated due to a change in resistance value between the two electrodes to which the leaked electrolyte is attached, that is, insulation deterioration. The detection circuit is characterized by detecting the leak current as a voltage change by flowing and making the change of the detected voltage the detected input voltage of the comparator section 17.

[0010]

[Action]

 The detection electrode 11 on the printed board functions to detect the leak voltage from the electrolytic capacitor by passing the leaked electrolytic solution from the electrolytic capacitor. Further, in the case of the two electrode means, the current flowing through the electrolytic solution extending between both electrodes serves to detect the voltage by giving a voltage drop from the bias voltage Vt to the detection electrode.

[0011]

【Example】

 (Embodiment 1) An embodiment of the present invention will be described with reference to the drawings. In FIGS. 1A and 1B, the wiring pattern on the printed board is used as the detection electrode 11, and this surface portion is not subjected to the resist printing process. This detection electrode makes it possible to detect a leak current due to leakage of the electrolytic solution of the electrolytic capacitor. Also, this electrode is subjected to solder plating, nickel plating, etc. to prevent the electrode from rusting during long-term operation. The resistor R1 has a high resistance value and is for applying the bias potential Vt to the detection potential. The resistor R2 is an input protection resistor for protecting the comparator IC of the detection input section.

The diode D1 is for clamping the overvoltage input potential together with the resistor R2, and is a Zener diode or a varistor. These protection circuits are used to protect the detection circuit from these high voltages because the voltage of the circuit used by the capacitor used in the power supply device is a high voltage of 150v to 300v. The capacitor C2 plays a role of a CR integration filter by R2 and C2 in order to prevent malfunction of the detection electrode due to electrostatic induction noise received from the switching circuit of the peripheral circuit and the like.

The resistors R3 and R4 set the detection threshold voltage of the comparator. The comparator 12 uses a comparator IC when the detection potential is on one side (only + or − potential), but uses a window comparator IC or the like when detection of both + and − potentials is required. The latch output FF 13 is reset and initialized by the reset 14 when the power is turned on. Then, the signal detected by the comparator is latched and held, and the alarm signal is output to the external control device.

The pattern shape of the detection electrode is arranged so as to surround the lead wire of the capacitor in order to facilitate detection of liquid leakage. However, ensure the insulation distance and the creepage distance that correspond to the circuit voltage.

In the vicinity of the lead wire on the high potential side of the capacitor (potential of 150 V to 300 V), this high potential is connected to the detection electrode through the resistance of the electrolyte leaking electrolyte, and this leak current is detected by the comparator 12. , Latch output FF13 is set and alarm output is performed to the outside.

Second Embodiment On the other hand, in order to be able to detect even in the vicinity of the lead wire on the low potential side of the capacitor (circuit common or ground potential), the detection electrode 11 has a Vt potential via a high resistance R1. Biased to. Since the change in the input voltage can be detected by the potential difference current between the bias potential and the low potential of the capacitor, it can be detected near both lead wires of the capacitor.

On the other hand, it is possible to detect even when the position where the liquid leaks is not near the lead wire depending on the mounting direction of the capacitor, when liquid leaks from the upper part of the electrolytic capacitor, or when the amount of liquid leak is very small. In order to achieve this, as shown in FIG. 1C, there is a structure in which the pattern of the ground electrode 16 is provided adjacently to the detection electrode 11 in close proximity. This ground electrode is connected to the circuit ground of the comparator circuit.

This is a structure in which a detection electrode and a ground electrode are provided adjacent to the detection electrode at a portion where the electrolytic solution leaked from the capacitor is likely to drop and adhere. Since the bias voltage Vt is applied to the detection electrodes, a current flows between the electrodes due to the resistance of the organic acid-based electrolytic solution attached, and the detection voltage biased by the high resistance R1 decreases. It can be detected by the comparator.

With the structure of both electrodes, it is possible to detect the liquid even if it is provided near the position where liquid leakage of the capacitor easily falls. In addition, since there is no high-voltage potential in the distance between the electrodes, the gap between the electrodes can be narrowed. Therefore, by providing a shape such as a comb pattern as shown in FIG. , Can be detected in a wide range.

Further, even if the capacitor is separated on another board, it suffices to connect the detection electrodes to each other with the electric wire 15 or the like as shown in FIG. 2, and the detection circuit can be provided at one place. Therefore, the increase in the space and cost of the new detection circuit can be minimized. In addition, at the time of manufacturing and assembling, it is possible to freely add or change the wiring of the detection electrodes according to the number of boards mounted and the configuration.

[0021]

[Effect of device]

 As explained above, the present invention is expected to prevent the occurrence of heat, smoke, or ignition by detecting electrolyte leakage at an early stage and outputting an alarm or outputting power. it can. In addition, it can be detected at an early point that an insulation failure due to liquid leakage will cause an electrical failure in the peripheral circuit, so that a power supply device with higher safety can be obtained.

Further, liquid leakage of a plurality of scattered electrolytic capacitors can be detected by a single detection circuit by providing only each detection electrode and connecting them. Similarly, the cost of the detection circuit can be minimized because the detection circuit can be made common to other boards simply by connecting it with an electric wire or the like.

[0023]

[Brief description of drawings]

FIG. 1 is a circuit diagram and an electrode shape of the present invention.

FIG. 2 is a diagram showing a connection of a plurality of boards of the present invention to an example of detection electrodes.

[Explanation of symbols]

 C1 Electrolytic capacitor 10 Liquid leakage electrolytic solution 11 Detection electrode 12 Comparator 13 Latch output FF 14 Reset 15 Wire 16 Ground electrode 17 Comparator part D1 Zener diode R1 to R4 Resistance C2 capacitor

Claims (2)

[Scope of utility model registration request] 1. In a detection circuit for a leaked electrolyte generated from an electrolytic capacitor of an electronic device, a structure in which a detection electrode (11) is pattern-wired near the electrolytic capacitor (C1) to form a detection electrode. Then, as a means for detecting a leak current due to deterioration of insulation between terminals due to electrolyte leakage from the capacitor, a change in the detected voltage due to the leak current is used as an input signal to the comparator section (17). A liquid leak detection circuit for an electrolytic capacitor, which comprises means for detecting a change in voltage with a comparator section (17). 2. The structure according to claim 1, wherein for detecting liquid leakage from the electrolytic capacitor, a ground electrode (16) is arranged adjacent to the detection electrode (11) by means of providing two electrodes. The detection electrode (11) has a high resistance (R1).
Is connected to one end of the high resistance, and a bias voltage (Vt) is applied to the other end of the high resistance to convert a change in the resistance value of the leak electrolyte into a voltage change, which is detected by the comparator section (17). Liquid leak detection circuit for electrolytic capacitors, which is used as a means of setting the input voltage.