JPH01170367A - Power source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switching regulator.

(Conventional Technique #) Conventional 1 For example, output control of a zero heat generation lamp for exposure in a copying machine is usually performed by phase control of a commercial power supply.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional example, there is a problem that the control signal needs to be generated in synchronization with the commercial power supply, which makes the circuit complicated and increases the cost.

On the other hand, it is possible to rectify and smooth the commercial power supply and switch it using a switching element, but this method generates large line noise and radio wave noise, which increases the cost of noise countermeasures. Since a separate power source is required to transform, rectify, and smooth the commercial power source as a power source for driving the device, there are problems in that power loss is large and unnecessary heat generation is caused.

The present invention was devised in view of these problems, and is an exposure method that does not increase costs and does not cause unnecessary heat generation.
The purpose of this invention is to provide a power supply device for a heat generating lamp or the like.

(Means for Solving the Problems) The present invention utilizes a switching regulator consisting of a line filter, a rectifying and smoothing circuit, a switching element, a transformer, etc., and after the line filter, a switching element, a heat generating lamp for exposure, etc. A series circuit with a load is connected, and the winding of the transformer is used as a power source for the drive circuit of the switching element.

[Effect]

With the above configuration, the line filter can be used in common with an existing device, and the device can also be used as a power source for a switching element drive circuit.

〔Example〕

The present invention will be explained below with reference to Examples.

FIG. 1 is a circuit diagram of a power supply device according to a first embodiment of the present invention.

In the figure, from a commercial power supply 3 to a line filter 4, a rectifier 5. DC power is obtained by the smoothing capacitor 6.

This DC power is switched by the first switching element 7, and AC power is obtained on its secondary side via an inverter transformer.

This AC power is rectified by diodes 9 and 10, and choke 11. It is smoothed by a capacitor 12 and supplied to the first load. The output voltage vCc supplied to the load is determined by the output voltage detection circuit 2. It is fed back to the power supply control circuit 14 via the photocoupler 1, compared with a reference voltage, and the first switching element is controlled by the comparison voltage, so that the output voltage V
cc is controlled to a predetermined value.

A series circuit of a halogen lamp 15 serving as a second load and a second switching element 18 is connected in parallel to the smoothing capacitor 6 .

The voltage of the halogen lamp 15 is detected by a voltage detection transformer 16, and then passed through an effective value conversion circuit 17 (a smoothing circuit consisting of a resistor, a capacitor, and a rectifier) to a light amount control circuit 20.
This value is compared with the control signal coming from another control circuit as the halogen lighting voltage to form a pulse width control signal, which is supplied to the control pole of the second switching element 18 via the photocoupler 19. The amount of halogen lighting light corresponding to the control signal can be obtained.

FIG. 2 is a circuit diagram of the main parts of a power supply device according to a second embodiment of the present invention.

As shown in the figure, a series circuit of a halogen lamp 15, which is a second load, and a second switching element 18 is connected to the output side of the line filter 4 via a halogen lamp rectifier 21.

In this case, the line filter 4 and inverter transformer 8 of the switching regulator for the first load can be shared by the switching regulator for the second load.

In each of the above embodiments, the halogen lamp is usually 300
Since many of them have high power of W or more, countermeasures against switching noise on the line are considered to be similar to those for switching regulators.

Therefore, by sharing the line filter and the rectifying and smoothing circuit, higher specifications of each element are required, but the cost and size are significantly lower than when they are incorporated separately.

〔Effect of the invention〕

As explained above, according to the present invention, the line filter and transformer can be shared by the power source for the first load and the power source for the second load, so it is possible to obtain a power supply device that is small, low cost, and generates little heat. can.

[Brief explanation of the drawing]

FIG. 1 shows a circuit diagram of a power supply device according to a first embodiment of the present invention, and FIG. 2 shows a circuit diagram of a second embodiment. In the figure, 4 is a line filter, 5 is a rectifier, 6 is a smoothing capacitor, 7 is a first switching element, 8 is an inverter transformer, 15 is a halogen lamp, and 18 is a second switching element.

Claims (2)

[Claims] (1) a line filter, a rectifying and smoothing circuit connected to the output side of the line filter, and a series circuit of a primary winding of a transformer and a first switching element connected to the output side of the rectifying and smoothing circuit; the first connected to the secondary side of the transformer
a series circuit of a second load and a second switching element connected after the line filter, and a drive circuit for the second switching element using the winding of the transformer as a power source. A power supply device characterized by: (2) The power supply device according to claim 1, wherein the series circuit of the second load and the second switching element is connected to the output side of the rectifying and smoothing circuit.