JPH10223382A - Halogen lamp lighting device and image formation device using this device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce flickers generated in a power source line due to a rush current in the initial period of lighting a lamp. SOLUTION: In the initial period of lighting, a lamp lighting control device 7 effects the PWM control of a two-way switch 6, and a current is carried to a halogen lamp 4 through a series circuit of a LC low-pass filter 5 and the two-way switch 6. Thereafter, the lighting control device 7 causes a triode AC switch 2 to be turned on through a photocoupler 3, and the two-way switch 6 is turned off by stopping the PWM control. In the initial period of lighting, high frequency components of a lamp current chopped by the two-way switch 6 are cut off by the LC low-pass filter 5 to reduce the amplitude of a rush current. Moreover, flickers generated in a power source line can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a halogen lamp lighting device for lighting a halogen lamp by an AC power supply, and an image forming apparatus such as a copying machine and a printer using the device.

[0002]

2. Description of the Related Art FIG. As shown, AC power supply 1, triac 2, halogen lamp 4
Are connected in series. The halogen lamp 4 is controlled to be turned on by inputting a signal from the halogen lamp lighting control device 1 to the photocoupler 3 connected between the main electrode and the gate electrode of the triac 2. FIG. 5 shows a timing chart of the signal and the lamp current.

[0003]

However, in the above-mentioned conventional example, since the AC power supply 1 of the power supply frequency (50 Hz, 60 Hz) is directly used for lighting the halogen lamp, there are the following problems.

When the halogen lamp 4 is lit in the configuration of the conventional example, as shown in FIG. 5, a current having several times the amplitude of the steady-state lighting is provided in a circuit provided with the halogen lamp 4 during the initial period of lighting. Rush current flows, and as a result, flicker occurs. The flicker adversely affects a power supply line connected to a power supply having the lighting device, and is a problem for other devices.

[0005] The present invention has been made under such circumstances, and a halogen lamp lighting device and a halogen lamp lighting device capable of reducing flicker generated in a power supply line due to a rush current at the beginning of lamp lighting. It is an object to provide an image forming apparatus using the same.

[0006]

In order to achieve the above object, the present invention provides a halogen lamp lighting device according to the following (1).
As described in (3) to (3), the image forming apparatus is changed to the following (4).
Configure as follows.

(1) A halogen lamp lighting device for lighting a halogen lamp by an AC power supply, comprising: a first lighting means having a thyristor; and a second lighting means having a series circuit of an LC low-pass filter and a bidirectional switch. And control means for controlling the second lighting means to be in an operating state at an initial lighting period, and thereafter, controlling the second lighting means to be in an inactive state and the first lighting means to be in an operating state. Halogen lamp lighting device.

(2) The halogen lamp lighting device according to (1), wherein the thyristor is a triac.

(3) The control means sets the bidirectional switch to PW
The halogen lamp lighting device according to the above (1) or (2), wherein the halogen lamp lighting device is operated by M control.

(4) An image forming apparatus comprising the halogen lamp lighting device according to any one of (1) to (3).

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail below with reference to an embodiment of a "halogen lamp lighting device" used for illuminating a document of a copying machine.

[0012]

FIG. 1 is a circuit diagram of a "halogen lamp lighting device" according to an embodiment. In this embodiment, as shown in FIG.
It comprises a C power supply 1, a halogen lamp 4, and lighting means 1 and lighting means 2 connected in parallel between them.
The lighting means 1 is composed of the triac 2 and the photocoupler 3 shown in the conventional example, and receives the signal of the lighting control device 7 which is the lighting control means of the lamp, and controls the lighting of the halogen lamp 4. The lighting means 2 has a configuration in which an LC low-pass filter 5 and a bidirectional switch 6 are connected in series, and the lighting of a halogen lamp 4 is controlled by a lighting control device 7 that controls the bidirectional switch 6.

FIG. 5 is a time chart of a lighting control signal and a lighting current when the halogen lamp is controlled by the lighting means 1 as in the conventional example. The period during which the lamp lighting signal is ON is a period t1 in which an inrush current flows and a period t2 in which the current is stable
Is divided into The maximum current amplitude p1 in the period t1 is equal to the period t2
When compared with the amplitude p2 of the steady current at the time, p1 is several tens times of p2, which causes flicker.

In this embodiment, the lighting device 1 and the lighting device 2 are controlled by the lighting control device 7 serving as lighting control means so that the current amplitude p1 which directly causes the flicker is reduced.
Operation is switched. FIG. 2 shows a timing chart of this switching. The operation is switched by a control signal of the lamp lighting control device 7 so that the lighting means 2 operates in the period t1 and the lighting means 1 operates in the period t2.

FIG. 3 shows a waveform of a current flowing through the halogen lamp 4. As shown in FIG. 1, assuming that the current flowing through the lighting means 1 is i2 and the current flowing through the lighting means 2 is i3, the current i4 flowing through the halogen lamp 4 is the sum of i2 and i3.
As described above, the current waveform of the halogen lamp during the period t1 is equal to the current i3. PWM control of the bidirectional switch 6 at least at a frequency higher than the power supply frequency
When the inrush current from the power supply is directly chopped, the waveform becomes as shown by the dotted line of the power supply i3 in FIG. In this embodiment, the AC power supply 1
Since the LC low-pass filter 5 is inserted between the switch and the bidirectional switch 6, the high frequency component is cut off, and a solid line waveform of the current i3 in FIG. 3 is obtained. From the maximum current amplitude p1 generated in the conventional configuration, A small current amplitude p3 is obtained. Therefore, an excessive rush current is suppressed and reduced, so that flicker generated in the power supply line is reduced.

As described above, according to the present embodiment, the flicker occurring on the power supply line at the initial stage of lamp lighting is reduced, so that the operation of other devices in the copying machine is not adversely affected.

[0017]

As described above, according to the present invention,
By lighting the halogen lamp with the newly added lighting means during the period when the rush current flows, excessive rush current is reduced, and as a result, flicker occurring in the power supply line is reduced. Further, according to the fourth aspect of the invention, flicker does not adversely affect other devices in the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of an embodiment.

FIG. 2 is a timing chart of an embodiment.

FIG. 3 is a diagram showing a current waveform in the embodiment.

FIG. 4 is a diagram showing a circuit configuration of a conventional example.

FIG. 5 is a diagram showing a current waveform in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Triac 3 Photocoupler 4 Halogen lamp 5 LC low-pass filter 6 Bidirectional switch 7 Lamp lighting control device

Claims (4)

[Claims] 1. A halogen lamp lighting device for lighting a halogen lamp by an AC power supply, comprising: first lighting means having a thyristor; second lighting means having a series circuit of an LC low-pass filter and a bidirectional switch; Control means for controlling the second lighting means to be in an operating state at an initial lighting period, and thereafter to control the second lighting means to be in an inactive state and the first lighting means to be in an operating state. A halogen lamp lighting device characterized by the above-mentioned. 2. The halogen lamp lighting device according to claim 1, wherein the thyristor is a triac. 3. The halogen lamp lighting device according to claim 1, wherein the control unit performs PWM control on the bidirectional switch so as to be in an operating state. 4. An image forming apparatus comprising the halogen lamp lighting device according to claim 1.