JP3194562B2 - DC high voltage generator - Google Patents

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. In addition, when lighting, 10kV to 20k
A trigger voltage of about V is required. Conventionally, this type of DC high-voltage generator has been configured to use a large amount of insulator. Also, considerable man-hours were required.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the required amount of insulator for a DC high voltage generator and to 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 rectifier circuit for receiving and rectifying a commercial alternating current, and high-frequency conversion by a switching element. A primary circuit, comprising: a first circuit for feeding a first winding of the transformer;
A high voltage rectifier circuit connected to the second winding of the transformer;
A secondary high voltage circuit comprising a multi-stage voltage doubler rectifier circuit having a capacitor having a capacitance sufficiently smaller than the capacitance of the smoothing capacitor of the high voltage rectifier circuit; and a power supply insulated by a third winding of the transformer. A control circuit that is supplied and operates, the control circuit sending a control pulse to the switching element via an insulating pulse transformer; and a DC high voltage generator that molds the secondary high voltage circuit with a synthetic resin. Forming a mold pack, mounting the mold pack on a printed circuit board, arranging most of the control circuit by surface mount components within a projection range of the mold pack on the back side of the printed board, The present invention proposes a direct-current high-voltage generator characterized by having the primary circuit attached thereto. 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. FIG. 2 shows an embodiment of an insulation structure.
(a) is a side view and FIG. 2 (b) is a bottom view.

First, the circuit configuration and operation will be described with reference to FIG. Input terminals 1, 2, and 3 receive 100 V or 200 V of a commercial AC power supply. Reference numeral 6 denotes a rectifier circuit for rectifying the commercial AC. Reference numeral 7 denotes a transformer, which generates a high-frequency high voltage in the secondary winding of the transformer 7 by switching the transistor Q1 as a switching element at a high frequency.
The multi-stage voltage doubler rectifier 9 is a circuit for applying a high trigger voltage when the load tube is started. The high-voltage rectifier circuit 8 is for supplying a steady-state current to the load tube. Reference numeral 11 denotes a voltage detection circuit. Upon receiving the detection signal, a constant voltage control circuit 14 generates a control signal to make the high voltage for trigger substantially constant. Reference numeral 12 denotes an output current detection circuit. Upon receiving the detection signal, the constant current control circuit 10 generates a control signal so as to keep the output current in a steady state constant. The constant voltage control signal and the constant current control signal are used as a control pulse 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 from the time when the input power supply of the DC high voltage generator is connected.

This DC high voltage generator can be roughly divided into a rectifier circuit 6, a switching element Q1, and windings n1, n3 of a transformer 7.
And a secondary high-voltage circuit 202 including a winding n2 of the transformer 7, a high-voltage rectifier circuit 8, a multi-stage voltage doubler rectifier circuit 9, etc., and power and signals from the winding n3 of the transformer 7. Control pulse generation circuit 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. Since the primary circuit 100 is connected to a commercial AC power supply, it can supply a large amount of energy and has a potential of several hundred volts with respect to the ground point, it is necessary to maintain sufficient insulation from other circuits. There is. The safety standards specify the withstand voltage with sufficient allowance. In order to satisfy this withstand voltage condition, it is required to keep the creepage distance on the printed board at a predetermined value.
Further, the secondary high voltage circuit 202 needs to maintain the insulation requirements from the primary circuit 101 and to maintain a sufficient withstand voltage against the maximum generated voltage. As for the control circuit 303, the voltage handled by its own circuit is within several tens of volts.
It is sufficient to prevent interference from other circuits.

Next, the insulation configuration 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 configuration of the mold pack 62 will be described in detail.
Prepare the transformer 65 and the secondary high voltage circuit 202
And the high voltage cable 17 and two pins 66 are attached.
As for the transformer 7, a so-called bobbin with pins is used, and each pin 7p is inserted into the printed board 65 and is electrically connected. As shown in FIG. 1, three of these pins 7p are on the secondary high-voltage side, so the three secondary high-voltage pins are printed circuit boards. Solder and cut short on the back side pattern surface of 65.
Other related to the primary circuit 101, ,,, (10)
(Instead of the symbol enclosing 10 in square brackets) and the control circuit 30
Pins related to 3 are printed circuit board 65
And extends to the position on the back surface of the printed circuit board 31. The printed circuit board 65 on which each component has been mounted in this way is
It is housed in 63 and molded with epoxy resin 64. The high-voltage inside is insulated by submerging the printed circuit board 65 slightly inside the end of the insulating case 63 and molding it.

[0009] The mold pack constructed as described above.
62 is mounted on the main printed circuit board 31. At the time of mounting, seven pins 7p extending from the transformer 7 and two pins 66
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 components can be constituted by surface mount components. Only the variable resistor RV1 and the electrolytic capacitors C12 and C13 of the components shown in FIG.
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. A bushing of about 5 mm thickness is used to insulate the protrusion of about 2 mm height on the back.
Attach. The bushings 61 are mounted at the four corners of the printed circuit board 31 and at a position close to the mold pack 62 substantially at the center of the printed circuit board 31.

Next, the primary circuit 101 is collectively mounted on the remaining surface of the printed circuit board 31.

[0011]

As described above, in the present invention, since the secondary high voltage circuit is molded with a synthetic resin to form a mold pack, only the high voltage portion is completely insulated. In addition, most of the control circuits are arranged by surface mount components within the range of projection of the mold pack onto the back surface of the printed circuit board.
It satisfies the insulation requirements for the secondary high voltage circuit, and at the same time, has a high capacity utilization. The primary circuits are collectively arranged on the printed circuit board, and the insulation separation distance is naturally ensured on the printed circuit board. Since the insulation structure of the DC high voltage generator is effectively configured in this way,
It is possible to reduce the size and weight by saving the insulating material. Also, the steps of the manufacturing method can be simplified.
Therefore, the economic effect is extremely large.

[Brief description of the drawings]

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

FIG. 2 shows an embodiment of the insulation configuration of the DC high voltage generator according to the present invention.

[Explanation of symbols]

1, 2, 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 generation circuit
31 ... Printed board 61 ... Bushing 62 ... Mold pack 63 ... Insulated case 64 ... Epoxy resin 65 ... Printed 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-68370 (JP, A) JP-A-60-166290 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 3/28

Claims (2)

(57) [Claims] 1. A transformer comprising a first winding, a second winding, a third winding, and a fourth winding, a first rectifier circuit for receiving a commercial alternating current and rectifying the same, and a switching device. A primary circuit for supplying power to a first winding of the transformer, a high-voltage rectifier circuit connected to a second winding of the transformer,
A secondary high voltage circuit comprising a multi-stage voltage doubler rectifier circuit having a capacitor having a capacitance sufficiently smaller than the capacitance of the smoothing capacitor of the high voltage rectifier circuit; and a power supply insulated by a third winding of the transformer. A DC high voltage generator comprising a control circuit which is supplied and operates and which sends a control pulse to said switching element via an insulating pulse transformer, wherein said secondary high voltage circuit is molded with a synthetic resin. Forming a mold pack, mounting the mold pack on one surface of the printed circuit board, and disposing a surface mount type component constituting the control circuit within a projection range of the mold pack onto the other surface of the printed circuit board; Further, the primary circuit is mounted on the remaining surface of the one side of the printed circuit board. 2. The DC high voltage generator according to claim 1, wherein said transformer is molded in said mold pack.