JP2592808B2 - Power supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power supply device that extracts a plurality of voltage outputs from the same transformer.

BACKGROUND OF THE INVENTION Conventionally, in electrophotographic copying machines, printers, and the like,
The low-voltage power supply for sequence control, the power supply for exposure, and the high-voltage power supply for charging were configured as independent power supply devices. For example, a charging high-voltage power supply has been configured so that a stabilized low-voltage power supply output (generally 24 V) is boosted to 5 to 9 KV by a DC-DC inverter. In such a conventional device,
There are drawbacks that many transformers and drive circuits are required, and that the power efficiency is reduced.

Further, when the transformer is integrated, a high voltage output is generated at the same time when the power is turned on, so that it is difficult to control the high voltage and there is a problem in terms of safety.

[Purpose] The present invention has been made in view of the above points, and a purpose thereof is to integrate a plurality of power supply transformers into a high-efficiency, low-priced, compact, and highly-safe power supply apparatus. Is to provide.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of a power supply device according to the present invention.
In the figure, 1 is a driving circuit of when to quenching transistor Tr ₁ power supply converter transformer T _1, 2 is Regiyureta circuit of the sequence control power source (24V in this embodiment). The core of the converter transformer T1 is _{1 at} the gap 3-1.
The secondary winding L _{1 is} divided into a low-voltage pair winding part of the secondary winding L ′ ₁ , and a primary winding L ₂ and a high-voltage pair winding part of the secondary winding L ′ ₂ . L _'2 is a high pressure is outputted to the high-voltage terminal P ₅ is rectified and smoothed by the high voltage diode D ₁ and high-voltage capacitor C ₁ in the secondary winding of the high pressure.

Now, when the power is turned on, it is energized in the primary winding L _1.
Secondary winding L _'1 is the output of the schematic 26~29VRMS across so are wound tightly coupled to the primary winding L ₁ is obtained, after rectified by D _2, stabilized 24V at Regiyureta circuit 2 After that, it is supplied to the sequence control circuit via the output terminals P ₃ and P ₄ .

At this time switch S ₁ remains at the open, not energized in the L ₂ winding, the high voltage winding L _'2, which is tightly coupled to the L ₂ is
Since not induced only leakage component only through the flux Giyatsupu 3-1 by R _1, the high voltage generating output to terminal P ₅ is reduced.

The sequence control circuit (not shown) enters the high pressure generation timing worked, switch S ₁ is being turned on.

S ₁ is composed of, for example, microswitch or an electronic switch.

Since switch S ₁ is being energized when it is turned L ₂ winding is induced a high voltage set in advance to the tightly coupled secondary winding L _'2, images charger through the terminal P ₅ DC high voltage required for formation is supplied.

FIG. 2 shows the current-voltage characteristics of the charger. The operating point during image formation is 6.3 KV, 400 μA,
It can be seen that the current is zero at KV and has no effect on the photosensitive drum at 4.8 KV or less.

When switch S ₁ blocking, high output since below 4KV be simultaneously high output power on it occurs no adverse effect of any way the photosensitive drum.

In Figure 3 shows a structural diagram of the actual winding of the transformer T _1. Ten
Is the magnetic core of the transformer.

The gap 3-1 shown in FIG. 1 is actually composed of the A, B and C gaps. Giyatsupu Part C is to reduce the voltage induced A, when S ₁ blocked is set sufficiently smaller than the B portion that is, L _'2 winding when not energized to L ₂ winding.

FIG. 4 shows an example in which a pair of primary winding L ₃ and secondary winding L ′ ₃ is additionally supplied to the fluorescent lamp 5.

Switch S ₂ is induced voltage required for lighting a closely-coupled L _'3 winding on the fed to L ₃ L ₃ by on, the voltage fed to the fluorescent lamp through the Chiyokukoiru 4. Since when S ₂ open most of the magnetic flux due to winding L ₃ energized by Giyatsupu 3-2 is interrupted, the voltage induced in L _'3 winding will not reach the lighting start voltage of the fluorescent lamp, fluorescent lamp not light.

In Figure 5 shows the structure of the actual winding of the transformer T _2.

As is clear from the above embodiment, the low-voltage power supply and the high-voltage power supply can be supplied from the same transformer, and the high-voltage output timing can be controlled by a sequence signal.

Further, as shown in FIG. 4, the power of the exposure power supply can be supplied and the exposure lamp can be turned on and off by the sequence signal.

In the present embodiment, the case where the present invention is applied to an image forming apparatus has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to any one that extracts a plurality of voltage outputs from the same transformer. It is.

[Effects] As described above, according to the present invention, a plurality of paired winding portions including a primary winding and a secondary winding provided on each of the cores of a transformer divided by a gap, Switch means for energizing at least one primary winding of the plurality of pair windings independently of the other primary windings, so that a desired pair winding is energized for a required period by providing the switch means. Can,
In addition, at this time, the output excited by the other windings can be reduced, so that adverse effects on other parts due to voltage generation can be reduced.

 Further, high efficiency, low cost, and downsizing can be achieved.

[Brief description of the drawings]

Block circuit diagram of Figure 1 is the power supply apparatus according to an embodiment of the present invention, FIG. FIG. 2 shows an example of the voltage-current characteristics of the charger, Figure 3 is the converter transformer T ₁ shown in Figure 1 FIG. 4 is a block circuit diagram of a power supply device according to another embodiment of the present invention, and FIG. 5 is a converter transformer shown in FIG.
It is a cross-sectional view of T _2. T ₁ , T ₂ … Converter transformer S ₁ … Switches L _{1 to} L ₃ … Primary winding L ′ _{1 to} L ′ ₃ … Secondary winding 1… Switching transistor drive circuit 2… Regulator circuit

Claims (3)

(57) [Claims] 1. A power supply device for extracting a plurality of voltage outputs from the same transformer, wherein a plurality of pairs of primary windings and secondary windings are provided on each of the cores of the transformer divided by a gap. A wire unit; and switch means for energizing at least one primary winding of the plurality of pair winding units independently of the other primary windings;
A power supply device comprising: 2. The method according to claim 1, wherein a low voltage is generated from one secondary winding of the plurality of pair windings, and a high voltage is generated from a secondary winding of the other pair windings. A power supply device characterized by generating: 3. A switch according to claim 2, wherein said switch means is operated so that power is supplied to a primary winding of said pair winding section for generating said low voltage simultaneously with power-on, and a predetermined sequence signal is generated. A power supply unit for operating the switch means so as to supply a current to a primary winding of the pair winding unit which generates the high voltage in response.