JPS6084969A - Power source device - Google Patents

Abstract

PURPOSE:To obtain an efficient power source by integrally constructing the first low voltage transformer and the second high voltage transformer, thereby enabling to omit the primary side drive circuit of a high voltage inverter transformer. CONSTITUTION:One end of the secondary winding W1 of an inverter transformer 4 is grounded, and the other end is connected to one end of the primary winding of an inverter transformer 8. A series connection of a resistor R3 and a capacitor C1 is coupled in parallel with the primary winding of the transformer 8, and the transistor TR1 is connected to the primary winding. On the other hand, a rectifier 9 which has a diode D2, is connected to the secondary winding of the transformer 8. The rectifier 9 is provided in a transformer integral with the transformers 4, 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a power supply device, and particularly to a power supply device that outputs low and high voltages and is used in electronic copying machines, laser beam printers, and the like.

[Prior Art] Devices such as electronic copying machines and laser beam printers generally use a plurality of power supply voltages: a low-voltage power supply for sequence control and a high-voltage power supply for powering a charger. In order to supply these different power supply voltages, conventional equipment converts commercial AC power into low-voltage DC and supplies it to sequence control circuits, lamps, solenoids, etc., and also converts this low-voltage output to an inverter. The voltage was boosted by a high-voltage power supply and supplied to high-voltage loads such as chargers. For this reason, in particular, high voltage output is supplied from the FJ AC power supply through low voltage and high voltage power supply circuits in accordance with the respective conversion efficiencies, resulting in a drawback of extremely low energy efficiency.

Furthermore, since two power supply circuits, one low voltage and one high voltage, are provided, the number of parts increases, which leads to an increase in the size and cost of the entire device.

In addition, a power supply device using a transformer in which a low-voltage winding and a high-voltage winding are wound on the same core has been proposed, but in such a configuration, the high-voltage output cannot be turned on and off by a sequence control signal, so the performance of the device is affected. The drawback is that it is limiting.

[Objective] The present invention has been made in view of the above points, and provides a highly efficient and reliable power supply device that can independently supply both high-voltage and low-voltage sources with a simple and inexpensive structure. The purpose is to

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 shows an embodiment of the present invention. The circuit in Figure 1 is a power supply device that outputs high and low voltages for use in electronic copying machines, etc. In the diagram, the reference numeral 1 indicates a commercial AC power supply, and this commercial AC power supply is connected to a rectifier circuit 2 and a constant voltage circuit 3. Power is supplied to the primary winding of the inverter transformer 4 through the inverter transformer 4. Inverter transformer 4 has three secondary windings W1
~W3, and the output of the secondary winding W2 is connected to the rectifier circuit 6.
From output terminal 12.13 through lamp, light/light,
A low voltage power supply of, for example, around 24V is supplied to the sequence control circuit and the like.

Further, the output of the secondary winding W3 is rectified by the rectifier circuit 7,
It is fed back to the inverter control circuit 3. Although not shown in detail, the inverter control circuit 3 is composed of switching transistors, an oscillation circuit, a PWM (pulse width modulation) circuit, an error amplification circuit, etc., and compares the rectified output of the secondary winding W3 with a reference value. Then, the energization time of the inverter I lance 4 is controlled so that the output of the inverter transformer 4 is constant.

Further, the output of the secondary winding W1 is coupled to the primary winding of a high-voltage inverter transformer 8 via a switch circuit 5, and the step-up output of the inverter transformer 8 is coupled to an output terminal 10.11 via a rectifier circuit 9. is supplied to high-voltage loads such as chargers. Here, the switch circuit 5 controls the output to the inverter transformer 8 and the subsequent high voltage load.

This high voltage output control is performed by a sequence control circuit (not shown).

2 to 5 show an example in which the inverter transformer 4 and the inverter transformer 8 in FIG. 1 are integrated together with the rectifier circuit 9. Fig. 2 shows its external appearance. In the figure, the reference numeral 4.8 indicates the inverter transformer 4 and impark transformer 8, and the reference numerals 15.16 and 15.16 indicate their respective cores. The windings are housed in a case 19 made of resin or the like with high thermal conductivity. In this embodiment, the output line of the inverter transformer 8 is taken out directly from the case 19 as shown. Note that the groove 18 provided between both transformers is for increasing insulation against exchanges.

More specifically, the cross section of the case 19 is constructed as shown in FIG. That is, the board 25 is inside the case 19.
Primary bobbin 22 of inverter transformer 4 fixed above
．． A secondary bobbin 23 and a primary bobbin 20 and a secondary bobbin 21 of the inverter transformer 8 are housed. Further, the parts of the case 19 other than the bobbin are filled with an epoxy-based insulating agent 26 having high insulation and high thermal conductivity by vacuum injection. It is installed inside the through hole. moreover,
A rectifier circuit 9 is installed in the case 19 on the inverter transformer 8 side.
Elements such as diodes and capacitors constituting are connected to the @ line and enclosed in -g. Note that here the code 2
Reference numeral 4 indicates the input or output terminals of the windings applied to each bobbin. The above configuration enables high-density packaging.

Furthermore, a heat sink is attached to the case 19 in order to radiate heat from each element of the rectifier circuit 9 inside the case 19. Figure 4 shows a heat sink 2 attached to the above-mentioned integrated transformer.
7 is shown attached. FIG. 4 shows a side view of the transformer shown in FIGS. 2 and 3. FIG. As shown in the figure, the heat sink 27 is fixed to the case 19 with screws 28, and at this time, the heat sink 27 is fixed so that its surface is in close contact with the case 19. More specifically, as shown in the cross-sectional view of FIG.
After filling the heat sink 27 with an insulating agent 26, the heat sink 27 is fixed with screws 28. At this time, if the radiation fins of the component 29 are brought into pressure contact with the inner wall of the case 19 using a pressing plate or the like as shown in the figure, the component 2
9 can be coupled to the heat sink 27 with very low thermal resistance, the heat dissipation effect can be enhanced, the life of the element can be extended, and the reliability can be improved. In addition, the heat sink 27 can particularly cut unnecessary noise radiated from the high-voltage trace.

Next, FIG. 6 shows an example of a specific configuration of a coupling portion between the inverter transformer 4 and the inverter transformer 8 shown in FIG. 1. Here, an example is shown in which a switching transistor is used in the switch circuit 5.

In the figure, one end of the secondary winding Wl of the inverter transformer 4 is grounded, and the other end is connected to the inverter transformer 8.
is connected to one end of the primary winding. A resistor R3 and a capacitor C are connected in parallel to the primary winding of the inverter transformer 8.
1 is connected in series, and the collector of a transistor TRI whose emitter is grounded is further connected to this primary winding. Further, a diode Di is connected between the core ground of this transistor TRI.

The base of this transistor TRI has resistors R1 and R
A control signal is input from terminal 14 through an attenuator consisting of two parts.

On the other hand, a rectifier circuit 9 consisting of a diode D2, a capacitor C2, and resistors R4 and R5 is connected to the secondary winding of the inverter transformer 8.

This rectifier circuit 9 is provided within a transformer in which the inverter transformer 4 and the inverter transformer 8 are integrally formed as described above.

In the second configuration, the rectifier circuit 2 and the inverter control circuit 3 are activated at the same time as the power is turned on (see Figure 1), low voltage power is supplied to the sequence F4JJ control circuit (not shown), and sequence control is started. Ru. Terminal 10.1
When the timing for energizing the high-voltage load connected to terminal 1 comes, the sequence control circuit applies a positive potential to terminal 14.

As a result, the transistor TRI becomes conductive, and in the positive half cycle, the primary '/iN line of the inverter transformer 8 is energized via the transistor TRI. In the negative half cycle, transistor TRI is cut off and diode Di
becomes conductive. In this way, alternating current is applied to the primary winding of the inverter transformer 8, and at the time of positive/negative conversion, the energy stored in the inverter lance 8 is supplied to the rectifier circuit 9 on the secondary winding side, and the rectifier circuit 9 supplies the rectified and smoothed DC voltage to a high voltage load such as a charger. Note that the diode Di also serves to prevent the transistor TRI from being destroyed by reverse voltage.

As described above, both low-voltage and high-voltage power supplies can be supplied to the load with a small number of parts, and in this case, the high-voltage power supplies can be independently sequence-controlled. In addition, high reliability can be achieved by using a highly thermally conductive insulating material, transformer case, and heat sink.

FIG. 7 shows a modification of the embodiment shown in FIG. 6, and the members designated by the same reference numerals in the drawing are the same as those in FIG. 6. As illustrated here. The transistor TRI is replaced with a SIRISK SCRl, and with such a configuration, the same effect as above can be obtained, and in this case, a larger current can be controlled.

The circuit shown in FIG. 6 can also be configured as shown in FIG. 8 if it is desired to supply constant current to a high-voltage load.

That is, in FIG. 8, 2 of the inverter transformer 8
The current of the rectified output on the next side is taken out as a voltage by resistors R5 and R6, and is amplified in an error amplifier 34 in relation to the error with the reference voltage applied from a terminal 35, and the output is sent to one input terminal of a comparator 33. be guided. The output of the secondary winding W1 of the inverter transformer 4 is integrated by the integrating circuit 31 and input to the other input terminal of the comparator 33. The output of this comparator 33 is connected to a gate 32 which is opened and closed by a control signal input from the terminal 14.
41 as in Figure 6 through! Completed switch circuit 5
The switching transistor TRI is controlled by the switching transistor TRI.

Figures 9(A) to 9(A) show signal waveforms during operation in the above configuration.
Shown in (D). Here, FIG. 9(A) shows the output waveform of the secondary winding W1 of the inverter transformer 4, and FIG. 9(B) shows the integral output P of the integrating circuit 31 and the output Q of the error amplifier 34.
, FIG. 9(C) shows the output of the comparator 33, and FIG. 9(D) shows the on timing of the transistor TRI. As shown in the figure, the comparator 33 compares the integration result of the secondary winding Wl with the reference voltage and the error on the secondary side of the inverter transformer 8. ) controls the switch circuit 5. Since the gate +-32 is opened by the sequence control circuit when performing high voltage output, the output of the comparator 33 is directly applied to the switch circuit 5 via the gate 32. At this time, as described in connection with FIG. 6, the transistor TRI is turned on only during the positive half cycle of the secondary @ line W1, as shown in FIGS. 9(A) and (D). The positive pulse width that drives this transistor TR'l corresponds to the output current on the secondary side of the inverter transformer 8, and if constants such as the reference voltage of the terminal 35 are set to appropriate values, the inverter transformer 8 Control can be performed to keep the current on the secondary side constant.

In the above embodiment, the secondary winding of the inverter transformer 4 has a
Although an example in which one high-voltage power supply circuit is connected is shown, it is also possible to connect a plurality of high-voltage power supply circuits. An example of this is shown in Figure 1O.

As shown in FIG. 1O, two high-voltage power supply circuits having exactly the same structure are connected to the secondary winding of the impark transformer 4. These high voltage circuits are similar to those shown in FIG. 8, and the integrator circuit 31 and gate 32 in FIG.
．． A constant current circuit consisting of a comparator 33, an error amplifier 34, etc. is indicated by the reference numeral 36 in FIG. Since the other members are the same as those shown in FIG. 8, their explanations will be omitted.

In addition to the above-mentioned advantages, the configuration described below has the advantage that several high-voltage power supplies can be independently controlled by the sequence control circuit.

Various modifications can be made in addition to the embodiments shown above.

They are listed below.

(2) In the above embodiment, the inverter transformer 8 has one secondary winding, but a plurality of secondary windings may be provided.

2) Although the inverter control circuit 3 suggests a passive inverter composed of switching transistors, oscillation circuits, PWM circuits, etc., the inverter transformer 4 may be provided with a feedback winding to provide feedback to the base of the switching transistor. It may also be constructed using a self-help inverter.

3) In the above embodiment, the inverter transformer 4 is provided with the secondary winding w3 for feedback to the inverter control circuit 3, but the rectified output of the secondary winding w2 may be directly fed back.

4) In connection with the above, feedback is performed from the secondary winding W1,
The output of the high voltage circuit at the subsequent stage may be stabilized.

5) Although Figures 2 and 3 show examples in which high-voltage rectifier circuit elements are enclosed within an integrated transformer, circuits that share the input commercial AC power supply and ground on the primary side of the inverter transformer 4, and other They may be enclosed at the same time.

6) Although FIG. 3 shows an example of a configuration in which the primary bobbin and the secondary bobbin are separated and housed in the transformer case, the primary and secondary windings may be wound on the same bobbin.

7) The heat sink 27 shown in Fig. 4 has the purpose of shielding unnecessary radiation noise especially from high-voltage windings, and although we have illustrated a structure that covers the entire Habo transformer, it can be used especially when shielding is not required. In this case, a heat sink of a size corresponding to the amount of heat dissipated can be installed at the required location.

8) The heat sink 27 may also be used as the case of the power supply unit or the main body case.

9) Although a zyristor is shown as an example of the switch means in FIG. 7, the circuit can be similarly constructed using a bidirectional thyristor, that is, a triac. In this case, the diode DI can be omitted.

10) Although FIGS. 8 and 10 show examples in which the high voltage output is made constant current, it is also possible to make the high voltage constant voltage by dividing the high voltage and supply it to the high voltage load.

As is clear from the explanation in "Effects" 2, according to the present invention, in a power supply device that supplies low and high voltage power supply voltages,
A first transformer for low voltage and a second transformer for high voltage are integrally constructed, and the primary winding of the first transformer and the second transformer are connected to each other.
Since the secondary winding of the transformer is connected via a switching element and a means for stabilizing the low voltage or high voltage output is provided, there are the following excellent advantages.

First, the primary side drive circuit of the high-voltage inverter transformer can be completely omitted, eliminating switching loss in the drive circuit and other energy losses that occur in conventional devices, making it possible to realize a highly efficient power supply device. In addition, for the same reason, it is possible to suppress the amount of heat generated due to noise or loss caused by switching, extend the life of the element, and furthermore enable high-density mounting.
This feature contributes to miniaturization and cost reduction of the entire device, and increases the reliability of the device as the number of parts decreases. Furthermore, the low-voltage circuit and high-voltage circuit can be sequence-controlled independently, expanding the functionality of the device and supplying stabilized power to the high-voltage load.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the power supply device of the present invention, FIG. 2 is a perspective view showing the structure of the transformer of the present invention,
Figure 3 is a sectional view of the transformer in Figure 2, Figure 4 is a cross-sectional view of the transformer in Figure 2,
3 is a side view of the transformer, FIG. 5 is a sectional view of the transformer shown in FIG. 4, FIG. 6 is a circuit diagram showing the circuit configuration of FIG. 1 in detail, and FIG. The circuit diagram shown in FIG. 8 is a block diagram when the high-voltage circuit of the power supply device of the present invention is made to have a constant current, and FIGS. The waveform diagram and FIG. 1θ are block diagrams showing a modification of the circuit in FIG. 8. ■...Commercial AC temperature 2.6.7.9...Rectifier circuit 3...Inverter control circuit 4.8...Inverter transformer 5...Switch circuit Wl-W3...Secondary winding Lines 10 to 13... Output terminal 14... Terminal 31...
Integrating circuit 32...Gate 33...Comparator 34...
error amplifier

Claims (2)

[Claims] (1) In a power supply device that supplies low-voltage and high-voltage power supply voltages, a first transformer for low voltage and a second transformer for high voltage are integrally configured, and the primary winding of the first transformer and A power supply device comprising means for connecting the secondary winding of the second transformer via a switching element to stabilize the low voltage or high voltage output. (2) The power supply device according to claim 1, wherein peripheral elements such as a rectifying element are enclosed within the case of the I-lance having the integral structure.