JPH0884469A - D.c. high voltage generator - Google Patents

Abstract

PURPOSE: To reduce the required amount of insulating material and the man- hours for a small-sized d.c. high voltage generator for use in helium-neon laser tubes or the like. CONSTITUTION: The d.c. high voltage generator consists of a primary circuit 101 which rectifies received utility alternating current and converts it into high- frequency waves by means of a switching element; a transformer that receives the high-frequency waves and boosts the voltage; a secondary high-voltage circuit 202 connected to the transformer 7; and a control circuit 303. Its insulation is structured as follows: First, high-voltage sections are put together into a mold pack 62. That is, the transformer 7 and the secondary high-voltage circuit 202 are assembled on a printed board 65, which is placed in an insulating case 63 and packaged by epoxy resin 64 molding. The thus obtained mold pack 62 is mounted on the surface of a printed board 31. The primary circuit 101 is mounted on the remaining surface of the printed board 31. Most of the circuit components in the control circuit 303 are mounted on the back of the printed board 31 mounted with the mold pack 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC high voltage generator and a method of manufacturing the same, and more particularly to a small DC high voltage generator used for a helium-neon laser tube and a method of manufacturing the same. .

[0002]

2. Description of the Related Art A helium / neon laser tube requires a high DC voltage of about 5 mA to 20 mA at a DC voltage of about 2 kV. Further, when lighting, 10kV to 20k
A trigger voltage of about V is required. Conventionally, this type of DC high voltage generator has a structure in which a large amount of insulator is used. Moreover, a considerable manufacturing man-hour was required.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the required amount of insulators for a DC high voltage generator and reduce the number of manufacturing steps.

[0004]

The present invention proposes the following means in order to solve this problem. A transformer including a first winding, a second winding, a third winding, and a fourth winding, a first rectifying circuit that rectifies by receiving commercial alternating current, and high frequency conversion by a switching element A primary circuit for supplying power to the first winding of the transformer,
A high voltage rectifier circuit connected to the second winding of the transformer,
A secondary high voltage circuit composed of a multi-stage voltage doubler rectifier circuit having a capacitor having an electrostatic capacity sufficiently smaller than the electrostatic capacity of the smoothing capacitor of this high voltage rectifier circuit, and being insulated by the third winding of the transformer and at the same time providing electric power. In a DC high voltage generator comprising a control circuit which is supplied and operates, and which sends a control pulse to the switching element through an insulating pulse transformer, the secondary high voltage circuit is molded with synthetic resin. A mold pack is constructed, the mold pack is attached to a printed circuit board, most of the control circuit is arranged by surface mount type components within the projection range of the mold pack on the back surface of the printed circuit board, and the remaining surface of the printed circuit board. Proposes a DC high voltage generator characterized in that the primary circuit is attached. Further, it is also proposed to mold the transformer including the transformer in the mold pack.

[0005]

FIG. 1 is a circuit diagram of a DC high voltage generator according to the present invention, and FIG. 2 shows an embodiment of an insulation structure.
(a) is a side view thereof, and FIG. 2 (b) is a bottom view thereof.

First, the circuit configuration and operation will be described with reference to FIG. Input terminals 1, 2 and 3 receive 100V or 200V of commercial AC power supply. Reference numeral 6 is a rectifying circuit for rectifying this commercial AC. Reference numeral 7 is a transformer, which generates a high frequency high voltage in the secondary winding of the transformer 7 by switching the transistor Q1 which is a switching element at a high frequency.
The multistage voltage doubler rectifier circuit 9 is a circuit for applying a high voltage for triggering when the load bulb is activated. The high-voltage rectifier circuit 8 is for applying a steady-state current to the load bulb. A voltage detection circuit 11 receives the detection signal, and a constant voltage control circuit 14 generates a control signal so that the high voltage for trigger is made substantially constant. Reference numeral 12 denotes an output current detection circuit, which receives the detection signal and generates a control signal so that the constant current control circuit 10 keeps the output current in a steady state constant. These constant voltage control signal and constant current control signal are made into control pulses by the synchronous control pulse generation circuit 22 and applied to the base of the transistor Q2 via the pulse transformer 21. When the transistor Q2 turns on, the transistor Q1 turns off. The timer circuit 13 is a safety device that starts its operation after a predetermined delay time from the time when the input power source of the DC high voltage generator is connected.

This DC high voltage generator is roughly classified into rectifier circuit 6, switching element Q1 and windings n1, n3 of transformer 7.
Power and signals from the primary circuit 101 including the transformer 7, the winding n2 of the transformer 7, the secondary high-voltage circuit 202 including the high-voltage rectifier circuit 8, the multistage voltage doubler rectifier circuit 9 and the like, and the winding n3 of the transformer 7. Synchronous control pulse generator 22 and constant current control circuit 10
And a control circuit 303 including a constant voltage control circuit 14, a voltage detection circuit 11, and an output current detection circuit 12. The primary circuit 100 is connected to a commercial AC power source, has a large energy that can be supplied, and has a potential of several hundred volts with respect to the ground point, so it is necessary to maintain sufficient insulation from other circuits. There is. The safety standard defines a pressure resistance that allows for sufficient margin. In order to satisfy this withstand voltage condition, it is required to keep the creepage distance on the printed circuit board at a predetermined value.
In addition, the secondary high-voltage circuit 202 needs to maintain the insulation requirement with respect to the primary circuit 101 and at the same time maintain a sufficient withstand voltage against the maximum generated voltage. Regarding the control circuit 303, the voltage handled by its own circuit is within several tens of volts,
It is sufficient to prevent disturbances from other circuits.

Next, the insulating structure of the DC high voltage generator according to the present invention will be described with reference to FIG. First, a portion to which a high voltage is applied is put together as a mold pack 62. The structure of this mold pack 62 will be described in detail.
65 is prepared and the transformer 7 and the secondary high voltage circuit 202 are provided on this.
Attach the high voltage cable 17 and the two pins 66.
For the transformer 7, a so-called bobbin with pins is used, and each pin 7p is inserted into the printed board 65 and electrically connected. As shown in FIG. 1, each of the pins 7p has three of the 10 pins on the high voltage side of the secondary side. Therefore, the three pins on the high voltage side of the secondary side are printed circuit boards. Solder on the back side of 65 and cut short.
Other primary circuit 101 related ... (10)
Pins (substituting symbols with 10 circles) and control circuit 30
For the pins related to 3, refer to PCB 65
And extends to a position on the back surface of the printed circuit board 31. Insulate the printed circuit board 65 on which each component is mounted in this way.
It is housed in 63 and molded with epoxy resin 64. The printed circuit board 65 is slightly sunk inward from the end of the insulating case 63 and is molded so that the high voltage inside is insulated.

Mold pack constructed in this way
62 is mounted on the main printed circuit board 31. At the time of mounting, the seven pins 7p and the two pins 66 of the transformer 7 are extended.
And are inserted into the printed circuit board 31 and attached. Then, the control circuit 303 is mounted in the projection range on the back surface of the mold pack 62. Since the voltage and current handled by this control circuit 303 are low, almost all parts can be configured with surface mount parts. Of the parts shown in Fig. 1, only the variable resistor RV1 and electrolytic capacitors C12 and C13 are large in size, so the printed circuit board
It is mounted adjacent to the mold pack 62 on the surface of 31, and all other components of the control circuit 303 are mounted on the back surface of the printed circuit board within a height of 2 mm. In order to insulate the protrusion of about 2 mm in height on the back side, a bushing of about 5 mm in thickness is used.
Attach. The bushing 61 is attached at four corners of the printed board 31 and at positions near the center of the mold pack 62 of the printed board 31.

Next, the primary circuits 101 are collectively attached to the remaining surface of the printed board 31.

[0011]

As described above, according to the present invention, since the secondary high voltage circuit is molded with the synthetic resin to form the mold pack, only the high voltage portion is completely insulated. Further, most of the control circuit is arranged by surface mount type components within the projection range of this mold pack on the back surface of the printed circuit board.
The secondary high-voltage circuit satisfies the insulation conditions and at the same time has a high volume utilization rate. The primary circuits are collectively arranged on the printed circuit board, and the insulation separation distance is naturally secured in the printed circuit board. Since the insulation structure of the DC high voltage generator is effectively constructed in this way,
The insulating material can be saved and the size and weight can be reduced. In addition, the manufacturing method can be simplified.
Therefore, the economic effect is extremely large.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a DC high voltage generator according to the present invention.

FIG. 2 shows an embodiment of an insulating structure of a DC high voltage generator according to the present invention.

[Explanation of symbols]

1, 2 and 3 ... Input terminal 4 ... Ground terminal 6 ... Rectifier circuit 7 ... Transformer 8 ... High voltage rectifier circuit 9 ... Multi-stage voltage doubler rectifier circuit 10 ... Constant current control circuit 11 ... Voltage detection circuit 12 ... Output current detection circuit 13 … Timer circuit 14… Constant voltage control circuit 15… High voltage output terminal 16… 0V terminal
17 ... High voltage cable 21 ... Pulse transformer 22 ... Synchronous control pulse generator
31 ... Printed circuit board 61 ... Bushing 62 ... Mold pack 63 ... Insulation case 64 ... Epoxy resin 65 ... Printed circuit board 66 ... Pin 101 ... Primary circuit 2
02… Secondary high voltage circuit 303… Control circuit Q1, Q2, Q3, Q4… Transistor
U1, U2 ... Comparator U3, U4 ... Operational amplifier C0 ... Stray capacitance of secondary winding of transformer 4

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Yamamoto 1-18-1 Takada, Toshima-ku, Tokyo Inside Origin Electric Co., Ltd.

Claims (2)

[Claims] 1. A transformer comprising a first winding, a second winding, a third winding and a fourth winding, a first rectifying circuit for rectifying commercial AC, and switching. And a high-voltage rectification circuit connected to the second winding of the transformer, and a high-voltage rectification circuit that is connected to the second winding of the transformer. A secondary high voltage circuit composed of a multi-stage voltage doubler rectifier circuit having a capacitor having an electrostatic capacity sufficiently smaller than the electrostatic capacity of a smoothing capacitor, and insulated by a third winding of the transformer and supplied with power to operate. A control circuit, comprising a control circuit for sending a control pulse to the switching element via an insulating pulse transformer, wherein a secondary high voltage circuit is molded with synthetic resin to form a mold pack. ， This mall Attach the pack to the printed circuit board,
Most of the control circuit is arranged by surface mount type components within the projection range of this mold pack on the back surface of the printed circuit board,
A DC high voltage generator characterized in that the primary circuit is attached to the remaining surface of the printed circuit board. 2. The DC high voltage generator according to claim 1, wherein the transformer is molded in the mold pack.