JPH11225436A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power supply unit which eliminates checks on a control system circuit, a load system circuit, etc., and by which the voltage of a load system can be made to rise easily after the voltage of a control system has been made to rise. SOLUTION: If a switch M is closed, a main control voltage control circuit B in a power supply unit A is made to operate, and a main control voltage V0 is made to rise to apply the voltage V0 to a main control circuit C for operation. In order to apply the voltage V0 to a sub-control circuit D or in order to cancel an energy save mode, the main control circuit C outputs an on signal to a 2nd switch F. By closing the 2nd switch F, a sub-control voltage V01 is applied to the sub-control circuit D, and the sub-control circuit D is made to operate and transmits a signal, by which a load G is put into a waiting state to a load control unit H. At the same time, an on signal is transmitted to a load voltage control circuit I. The load voltage control circuit I is made to operate, a load voltage V1 is made to rise and the load voltage V1 is applied to the load G. Therefore, the load voltage V1 is made to rise after the sub- control voltage V01 is securely made to rise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus, a printer, a personal computer, a facsimile machine,
The present invention relates to a power supply unit such as a copying machine, and more particularly, to a power supply unit in which a voltage of a load system always surely rises after a control system voltage rises.

[0002]

2. Description of the Related Art Conventionally, after a control system voltage rises in a power supply circuit of an image forming apparatus, an error amplifier is used to raise the voltage of a control system (Example 5).
V) is monitored, it is confirmed that the voltage of the control system has risen, and the technology of a power supply circuit for raising the voltage of the load system (for example, 24 V) is already known from Japanese Patent Application Laid-Open No. 4-54826.

[0003]

In a power supply circuit of an image processing apparatus, a copying machine, a printer, a facsimile apparatus, or the like, when the voltage of the load system rises first and then the voltage of the control system rises, the control system operates. Since the voltage of the load system is input at a time when the load is not present, there is a possibility that the IC or the like may be damaged. Therefore, the voltage of the control system rises first,
Thereafter, it is necessary to guarantee that the voltage of the load system rises.

Therefore, a first object of the present invention is to raise the voltage of the control system first, and then to raise the voltage of the load system. An object of the present invention is to provide a power supply unit such as an image forming apparatus in which the voltage of the control system rises reliably after the voltage of the control system rises without requiring the setting of constants such as an amplifier circuit, a resistor, and a capacitor. A second object of the present invention is to provide a power supply unit for preventing a large inrush current from flowing through the switch when the internal switch of the unit is turned on, thereby preventing the switch from being damaged.

[0005]

According to the first aspect of the present invention, in a power supply unit of an image forming apparatus including a main control circuit, a sub control circuit, and a load voltage control circuit, a power supply is turned off.
A main switch to be turned on / off, a main control circuit operating means for operating the main control circuit when the main switch is turned on or when the energy saving mode is released, and a main control circuit operated by the main control circuit operating means to be turned on. A second switch, a voltage detecting means for detecting a sub-control voltage between the second switch and the sub-control circuit, and when the voltage detecting means detects a voltage, the load voltage control circuit operates and the load voltage rises The first object is achieved by providing a load voltage rising means.

According to a second aspect of the present invention, in the first aspect, a pulse signal generating means for generating a pulse signal for several seconds as a signal for turning on the second switch;
Transmission means for transmitting the pulse signal to the second switch is further provided to achieve the second object. According to a third aspect of the present invention, in the first aspect of the present invention, as the signal for turning on the second switch, a pulse signal generating means in which the pulse width of the pulse signal of several seconds gradually increases, A transmission means for transmitting the data to the switch is further provided, thereby achieving the second object.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG.
1 is a circuit diagram showing a configuration of an embodiment of the present invention.
This electric circuit includes a main control voltage control circuit B, a main control circuit C, a sub control circuit D, a second switch F, a load G,
It comprises a load control section H, a load voltage control circuit I, and a main switch M. In such a configuration, when the main switch M of the image forming apparatus is turned on or the energy saving mode is released, the main control voltage control circuit B in the power supply unit A operates and the main control voltage V0
When V0 (5 V in this embodiment) rises, the main control circuit C is applied with the voltage V0 (5 V) and operates.

Next, the main control circuit C issues an ON signal to the second switch F to apply the voltage V0 to the sub control circuit D or to cancel the energy saving mode. In the present embodiment, a transistor is used for the second switch F. When the second switch F receives the ON signal and turns on, the sub-control circuit D turns on the sub-control voltage V01 (5
The sub-control circuit D detects this by being applied to V), and sends a signal to the load control unit H such that the load G is in a standby state. At the same time as the second switch F is turned on, an ON signal is sent to the load voltage control circuit I, the load voltage control circuit I operates, the load voltage V1 (in this embodiment, 24V) rises, and each load G Is applied by the voltage V1. As described above, in the present embodiment, after the main switch M is turned on, the main control circuit voltage is turned on, the sub control voltage V01 in the power supply unit A rises, and the sub control voltage V01 is used as a trigger to control the load voltage. Since the circuit I operates, the load voltage V1 rises after the sub-control voltage V01 rises without fail.

As shown in FIG. 2, the main control circuit C sends an ON signal to the second switch F, and when the switch F is closed, a current is supplied to each electric component of the sub-control circuit D. A large inrush current J flows. However, this large inrush current J may generate a breakage of the switch element or the like. Therefore, in the present embodiment, the main control circuit C
However, by transmitting a pulse signal as an ON signal for several seconds as shown in FIG. 3 to the second switch F, current is supplied to each electric component of the sub-control circuit D little by little, and as shown in FIG. The current K is controlled.

Further, the main control circuit C transmits to the second switch F a signal whose pulse width gradually increases for several seconds as shown in FIG. Further, by supplying the current little by little, the inrush current J in FIG. 2 or the inrush current K in FIG.
Is controlled (rush current L) as shown in FIG.

[0011]

According to each of the first to third aspects of the present invention, in the power supply unit of the image forming apparatus, the control system and the load system are studied in the same manner as in the prior art (the constant setting of an error amplifier circuit, a resistor, a capacitor, etc.). ) Is unnecessary, and the power supply unit in which the voltage of the load system rises after the voltage of the control system rises easily and inexpensively can be provided.

According to the second aspect of the present invention, in a power supply unit such as an image forming apparatus, damage of a switch element in the power supply unit can be easily prevented. Furthermore, in the power supply unit such as an image forming apparatus according to the third aspect of the present invention, it is possible to more easily prevent the switch element in the power supply unit from being damaged than the second aspect of the invention.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is an example of an inrush current J generated in a second switch.

FIG. 3 is an example of a pulse signal for several seconds transmitted to a second switch.

FIG. 4 is an example in which an in-rush current J is controlled by making an ON signal transmitted to a second switch a pulse signal for several seconds.

FIG. 5 is an example of a pulse signal transmitted to the second switch and having a pulse width gradually increased for several seconds.

FIG. 6 is an example in which the inrush current J is further controlled by setting the ON signal transmitted to the second switch to a pulse signal in which the pulse width gradually increases for several seconds.

[Explanation of symbols]

 A power supply unit B main control voltage control circuit C main control circuit D sub-control circuit F second switch G load H load control unit I load voltage control circuit J, K, L inrush current M main switch

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H02M 3/28 H04N 1/00 C H04N 1/00 G06F 1/00 330H 334D

Claims (3)

[Claims] 1. A main switch for turning on / off a power supply in a power supply unit of an image forming apparatus including a main control circuit, a sub control circuit, and a load voltage control circuit; A main control circuit operating means for operating the main control circuit, a second switch which is turned on when the main control circuit is operated by the main control circuit operating means, and a sub-control between the second switch and the sub-control circuit. A power supply unit comprising: voltage detecting means for detecting a voltage; and load voltage rising means for operating a load voltage control circuit when the voltage is detected by the voltage detecting means, whereby the load voltage rises. 2. A pulse signal generating means for generating a pulse signal for several seconds as a signal for turning on the second switch;
2. The power supply unit according to claim 1, further comprising a transmitting unit that transmits the pulse signal to the second switch. 3. A signal generator for turning on the second switch, further comprising: pulse signal generating means for gradually increasing the pulse width of the pulse signal of several seconds to several seconds; and transmitting means for transmitting the pulse signal to the second switch. The power supply unit according to claim 1, wherein: