JPS6311868B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device for pulse plating, which applies pulse current to a member to be plated to plate the member.

[Conventional technology]

A pulse plating method has been proposed in which a pulsed current is repeatedly applied for milliseconds in order to obtain a dense and uniform plating with few pinholes. As a power supply device for such pulse plating, one is used in which a transistor is inserted between a DC power source and a load, and the transistor is turned on and off, and the current or voltage when it is on is controlled. There is.

FIG. 1 is a wiring diagram showing the configuration of this type of conventional power supply device for pulse plating. In the figure, a rectifier circuit 2 and a smoothing capacitor 3 are connected to a transformer 1 that steps down an AC voltage from a commercial power supply to an appropriate value, forming a well-known DC power supply circuit. A control transistor 5 is provided between this DC power supply circuit and an output terminal 4 that connects a covered member as a load, and a current detector 6 is connected in series with the load circuit. Further, the control circuit 7 controls the control transistor 5 based on the signal from the current detector 6 and the signal corresponding to the energization period and the rest period output from the repetition timer circuit 8.

Next, the operation will be explained. The AC voltage stepped down by the transformer 1 is rectified by the rectifier circuit 2, and smoothed by the capacitor 3 to obtain a stable DC voltage. The repetition time limit circuit 8 can arbitrarily set an energization period and a rest period of 1 second or less, for example.
With this setting, a rectangular wave signal whose energization period is at the "H" level and the rest period is at the "L" level is repeatedly output. The control circuit 7 turns the control transistor 5 on (hereinafter referred to as on) when the output level of the repetition timer circuit 8 is "H", and turns the control transistor 5 off (hereinafter referred to as "on") when the output level of the repetition timer circuit 7 is "L". (hereinafter referred to as off). As a result, a pulsed current is repeatedly passed through a load (not shown) to perform the above-mentioned pulsed plating. In this case, the current flowing through the load is detected by the current detector 6 and the detection signal is taken into the control circuit 7. The control circuit 7 also includes a setting device that sets a current reference for the load, and compares this current reference with the current detection value of the current detector 6, and controls the control transistor 5 so that the deviation becomes zero. Control.

In this way, a pulsed current having an energization period and a rest period set by the repeating time circuit and having a magnitude set by the control circuit 7 is passed through the plated member as a load.

[Problem that the invention seeks to solve]

Generally, in pulse plating, it is said that good quality plating can be obtained by keeping the magnitude of the rectangular wave current constant and increasing the current rapidly. In the conventional pulse plating power supply device mentioned above,
In order to satisfy this condition for a variety of loads, the DC power supply voltage was made considerably high. on the other hand,
The voltage across the load, ie, the load voltage, is not constant and is often low. This means that a differential voltage obtained by subtracting the load voltage from the DC power supply voltage is applied across the control transistor 5, resulting in a power loss corresponding to the product of this differential voltage and the load current.

Therefore, in the conventional power supply device for pulse plating, efficiency decreases due to large power loss, and in addition to using a large-capacity transistor that can withstand this power loss, it is necessary to house the transistor and provide sufficient heat dissipation. There were problems in that the price of the equipment soared and the operating cost also increased because of the need to carry out this process.

This invention was made to solve the above problems, and provides a power supply device for pulse plating that can supply direct current with high efficiency and can significantly reduce the device price and operating cost. The purpose is to

[Means for solving problems]

This invention includes: a first DC power source that adjusts a voltage and applies it to a load; a current control element provided between the first DC power source and the load; and a voltage larger than the first DC power source. a second DC power source that applies the voltage to the load; a switching element provided between the second DC power source and the load; and a switching element that repeatedly generates a signal that changes in two ways corresponding to an energization period and a rest period. a repetitive timer circuit for outputting an output; a current detector for detecting the current flowing through the load; and a current detector for controlling the current control element on and off in accordance with changes in the output signal of the repetitive timer circuit; a first control circuit that controls the switching element so that the current detected when the switching element is on matches a reference value, and controls the switching element to be turned on for a predetermined time when the current flowing through the load rises; 1st
storage means for sampling and storing the voltage of the load when only the DC power source of the first DC power source is supplying current; The present invention is characterized by comprising a second control circuit that controls the DC power supply.

[Effect]

In this invention, a first DC power supply whose voltage can be adjusted is used to flow a pulse current according to the output of the repetitive timer circuit, while a second DC power supply whose output voltage is higher than that of the first DC power supply is used. Using the first DC power supply, the rising waveform of the load current is improved, and the load voltage when only the first DC power supply is supplying current is memorized, and the output voltage is higher than this voltage by a predetermined value. Since the first DC power supply is controlled in this manner, the voltage across the current control element provided between the first DC power supply and the load can be held approximately constant, and thereby Direct current can be supplied with high efficiency, and the device price and operating cost can be significantly reduced.

〔Example〕

FIG. 2 is a wiring diagram showing the configuration of an embodiment of the present invention, and elements that are the same or have the same effect as those in FIG. and,
A voltage adjustment circuit 9 is newly provided between the capacitor 3 described in FIG. 1 and the control transistor 5 as a current control element. This voltage adjustment circuit 9
is composed of transistors, reactors, capacitors, etc., and the output voltage can be adjusted by controlling the on/off time ratio of the transistors. In this case, if the sample-and-hold circuit 10 samples and stores the voltage at the output terminal 4 at a timing when only the control transistor 5 is supplying current to the load, the control circuit 11 will raise the voltage by a certain voltage higher than the stored voltage. The voltage adjustment circuit 9 is controlled so as to achieve the following. Furthermore, a diode 12 is provided on the output side of the control transistor 5 to prevent current from flowing around. On the other hand, a rectifier circuit 13 is connected to the secondary side of the transformer 1 so that a voltage approximately twice as high as that of the rectifier circuit 2 can be extracted, and a smoothing capacitor 14 is further connected to the rectifier circuit 13. ing. Also,
A transistor 15 as a switching element is provided between the rectifier circuit 13 and the output terminal 4, and a control circuit 7 turns on and off the transistor 15. Note that the transformer 1, rectifier circuit 2, capacitor 3, and voltage adjustment circuit 9 shown in FIG.
corresponds to the second DC power supply of the present invention.

The operation of this embodiment configured as described above will be explained below with reference to the time chart of FIG.

First, the DC voltage obtained by the rectifier circuit 13 and the capacitor 14 is approximately 2 times higher than the DC voltage obtained by the rectifier circuit 2 and the capacitor 3.
It's doubled. In this state, as shown in FIG. 3a, the repetition timer circuit 8 outputs a pulse signal P in which the time it becomes "H" is W and the time it becomes "L" is R, corresponding to the energization period and the rest period. Then, as shown in FIG. 3b, the control circuit 7 causes a current I _b1 corresponding to the pulse signal P to flow through the base of the transistor 5, and
The magnitude of the base current I _b1 is changed so that the deviation between the current reference and the current detection value of the current detector 6 becomes zero. Further, as shown in FIG. 3c, the control circuit 7 causes the base current to flow into the transistor 15 only at the beginning of the time width W corresponding to the energization period, that is, for a very short time T when the load current rises. I flow _b2 . As a result, a DC voltage with a time width of approximately W and a DC voltage with a time width of approximately T and twice the time width are repeatedly applied to the load connected to the output terminal 4. Figure 3d shows the current flowing through the load,
If only a DC voltage with a time width W is applied with the voltage kept low in order to reduce power loss, only a slow rising current I _M will flow, but a DC voltage with a time width of approximately T and twice the magnitude will flow. When both are added, a current _IN with a steep rise flows, and the current waveform can be approximated to a suitable current waveform for obtaining high-quality licking. In this case, the time width T is adjusted to the time from the start of energization until the deviation between the current reference and the detected current value becomes equal to or less than a certain value. On the other hand, the sample hold circuit 10
As shown in FIG. 3e, sampling is performed at an appropriate time within the time width S excluding the time T when a large DC voltage is applied.

In this way, when a large voltage is applied for a short time when the load current rises, the voltage applied via the control transistor 5 can be low. The voltage adjustment circuit 9 is provided to suppress this voltage to a low level and reduce the power loss of the control transistor 5, and the control circuit 11 adjusts the voltage of the sample and hold circuit 10 in consideration of the voltage drop of the transistor 5 and the diode 12. The voltage adjustment circuit is controlled so that an output voltage that is higher than the storage voltage by a certain value is obtained. As a result, only a constant voltage necessary for its operation is applied to the control transistor 5, so power loss can be minimized.

On the other hand, the DC power supply consisting of the transformer 1, the rectifier circuit 13, and the capacitor 14 only needs to supply current for a short time at the beginning of each energization period, so it can be easily made small, and of course, the transistor 15 can also be made with a small capacity. It is clear that this will suffice.

Note that the load voltage is not determined during the first energization,
Although the sample and hold circuit 10 does not store a valid voltage value, the voltage adjustment circuit 9 is configured to output the highest voltage only at this time. This allows the necessary current to be supplied to any load. At this time, the control transistor 5 becomes overloaded, but it does not cause any trouble because the load quickly becomes appropriate only for a short time at the start of operation.

Thus, according to this embodiment, since the power loss of the control transistor is minimized, direct current can be supplied with high efficiency, and the capacity of the control transistor can also be small, reducing the device price and operating cost. It can be significantly reduced.

In the above embodiment, the DC power supply is comprised of a transformer 1, a rectifier circuit 2, a smoothing circuit 3, and a voltage adjustment circuit 9, and is of a type that changes the on/off time ratio of transistors, so it is relatively immune to load fluctuations. This can be done quickly, and instead of this DC power supply, a DC-DC converter can be used after direct rectification.Furthermore, a thyristor can be used instead of a transistor, although the response speed will be somewhat slower.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the first DC power source whose voltage can be adjusted is used as a device for passing a pulse current according to the output of the repetitive timer circuit. Using a second DC current with a higher output voltage than the first DC power supply, the rising waveform of the load current is improved, and
The load voltage when only the first DC power supply is supplying current is stored, and the first DC power supply is controlled so that the output voltage is higher than this voltage by a predetermined value. The voltage across the current control element installed between the DC power source and the load can be held approximately constant, which allows DC current to be supplied to the load with high efficiency, while reducing equipment price and operating costs. The effect is that it can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram showing the configuration of a conventional power supply device for pulse plating, Fig. 2 is a wiring diagram showing the configuration of an embodiment of the present invention, and Figs. 3 a to e explain the operation of the same embodiment. This is a time chart for 1... Transformer, 21, 13... Rectifier circuit, 3,
14... Capacitor, 5... Control transistor,
6... Current detector, 7, 11... Control circuit, 8...
... Repetitive time limit circuit, 9... Voltage adjustment circuit, 10...
Sample and hold circuit, 15...transistor.

Claims (1)

[Claims] 1. A first DC power source that adjusts a voltage and applies it to the load; a current control element provided between the first DC power source and the load; and a current control element that applies a voltage higher than the first DC power source to the load. a second DC power supply applied to the switching device; a switching element provided between the second DC power supply and the load; and a repetition method of repeatedly outputting a signal that changes in two ways corresponding to an energization period and a rest period. a timer circuit, a current detector that detects the current flowing through the load, and turning on the current control element in response to a change in the output signal of the repetitive timer circuit;
At the same time, the switching element is controlled so that the on-state current detected by the current detector matches a reference value, and the switching element is turned off for a predetermined time when the current flowing through the load rises. a first control circuit that performs on-control; a storage means that samples and stores the voltage of the load when only the first DC power supply is supplying current; and an output that is higher than the voltage stored in the storage means. A power supply device for pulse plating, comprising: a second control circuit that controls the first DC power supply so that the voltage increases by a predetermined value.