JPS5866534A - High voltage 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 The present invention relates to a high voltage power supply device used in copying machines and the like.

In general, copying machines require a high-voltage power supply to charge and neutralize the photoreceptor drum and to separate the transfer paper from the photoreceptor drum.As copying machines are becoming smaller and lighter, high-voltage Power supplies are also required to be smaller and lighter. One copier can have two to two high voltage DC outputs.
3 and 1 high voltage AC output are required, and it is being considered to house these in one housing for miniaturization.

However, when all of them are put together, the power supply device becomes large and there is no flexibility in terms of the space for setting it inside the copying machine.

For this reason, a method has been adopted in which they are distributed around the photoreceptor drum. Specifically, the DC power source for static elimination and the AC power source for stripping are housed in the same housing, and the DC power source for charging is housed in a separate housing.

Among the above-mentioned dual power supply devices, there are some that simply use a common power source input, but obtain AC output and DC output using completely separate circuits.

This is 400 to 400 on the copying machine side for AC output etc.
Since stripping operation is now possible at a frequency of 500Hz, it has become possible to be smaller and lighter than conventional ferro-resonant high-voltage transformers.Also, the DC output can be reduced to less than 2009 at DC7KV due to high-voltage insulation and improved circuit technology. Because it has become possible to make it smaller and lighter, a combined AC/DC high-voltage power supply is being manufactured with the same volume as a conventional commercial frequency AC single output iron-resonant high-voltage transformer. Although this method is stable in terms of characteristics and reliability and is relatively reasonable, it has a limit in terms of further miniaturization.

For this reason, conventionally, a device as shown in FIG. 1 has been used. First, a control circuit section (3) including an oscillation transistor (2) and a transformer (
A feedback circuit (5) is connected to the secondary side of the transformer (4), and a variable resistor (6) is connected to the transformer (4).
An AC terminal (8) from which an AC output is required is connected via a resistor (7) and a resistor (7). Further, a series circuit of a diode (9) and a capacitor α1 is connected to the secondary side of the transformer (4), and a DC output is provided at the midpoint of these connections via a variable resistor (0]) and a resistor (6). The DCC terminal ring required is connected.

Therefore, the secondary winding output of the transformer (4) is directly used as an AC output, which is then rectified to become a DC output. Therefore, the transformer (4) and the control circuit section (3)
) is sufficient, and miniaturization is possible. However, in such a configuration, since there is only one transformer (4), the control circuit section (3) cannot simultaneously control AC and DC load fluctuations, and the control circuit section ( 3) deals only with input voltage fluctuations. A transformer (
By improving the coupling ratio of 4) and lowering the internal impedance, the voltage drop of the transformer (4) due to load fluctuations can be eliminated. Still, the output must be varied on the high voltage side using variable resistor (6) α■. However, in order to avoid an increase in the load fluctuation rate due to the voltage drop of this resistance, a dummy current higher than the load current is connected to the resistor (7).
It is necessary to compensate for the increase in the impedance of variable resistor (6) α by pouring it into H. Therefore, even if it is possible to take measures against load fluctuations, the following drawbacks arise.

First of all, the power consumption increases due to the current flowing into the variable resistor (6) α and the resistors (7) and (6). Second, input/output conversion efficiency decreases. Thirdly, with DC output, a dummy current is added in addition to the output load current, so in order to compensate for the drop in output impedance and increase in pull voltage, the capacitance of the capacitor α must be increased, making it possible to reduce the size. go against the grain. Fourth, variable resistor (6) (11)
, resistors (7) and (6) are for high voltage and high power, and are therefore expensive. Fifth, the variable resistor (6) is AC (40
Since the high voltage is variable from 0 to 500H2), technical and reliability problems will occur unless the design is very careful in terms of life span and noise level due to high voltage corona. This type of volume is usually a metal glaze resistor, which is made by mixing and sintering a glass insulator and a conductor such as ruthenium.
When the frequency is relatively high such as 500H2, corona is generated in the ruthenium conductor around the contact through the space apart from the current-carrying part between the contact and the resistor, shortening the life of the contact and the resistor, and causing a large amount of damage. It generates noise.

The present invention has been made in view of these points, and it is an object of the present invention to provide a high-voltage power supply device that is reliably reduced in size and weight without any technical difficulty.

The present invention provides an AC transformer and a DC transformer provided in the same housing.
), the ACl lance handles most of the AC output and DC output, and the DC output is the sum of the rectification from the AC output and the DC output rectification generated by a separate DC transformer. D by transformer
The C output component is responsible only for adjusting the output voltage of all DC outputs, and this allows stable operation similar to when AC and DC outputs are obtained from separate transformers by simply adding an extremely small DC transformer. The structure is such that the overall size and weight can be reduced as well as the overall performance.

An embodiment of the present invention will be explained based on FIGS. 2 to 4. First, a control circuit section 0 including an oscillation transistor α and an AC lance 0'I) are connected to the DC power supply α, and a control circuit section α including an oscillation transistor α and an extremely small DC transformer are connected. (1) is connected. Here, a control circuit section (1O is a single-stone sine wave inverter. The AC transformer 0 is an AC terminal from which an AC output is taken out) is connected, and a feedback circuit connected to the control circuit section α→ Circuit (c) is connected. In addition, the AC) lance 0 has a diode @
, a series circuit of capacitors (C) is connected between the ground, a DC terminal (C) for taking out the DC output is connected to the midpoint between the diode (C) and the capacitor (C), and the capacitor (C) is The DC transformer (c) is connected to the middle point of the connection of
C) is connected via a diode (A). In addition, there is a resistor (E) in addition to the capacitors (C) and (C).
(E) are connected in parallel, and a series circuit of a resistor (G) and a variable resistor 01) is connected to these resistors (C) and (C). A feedback circuit 0 is connected between this variable resistance (three cores and the control circuit section α).

In such a configuration, the AC) lance α force is 400~
It oscillates at 500 Hz and has a frequency of 5.5 KVRM.
An AC output with SO value is obtained. This output line is rectified by a diode, charged to a capacitor (C), and smoothed to obtain the rectified DC component (V(:x)l) from the AC lance (1).Here, The value of the discharging and dividing resistor (c) is set to R, > R2.

At the same timing as this action, the action on the DC) lance side is also performed. This oscillation frequency is a high frequency of about 20 to 30 KHz, and the secondary voltage is charged to the capacitor (C) through the diode (C). In this case, AC transformer 0
The constant of the resistor (c) is determined so that the voltage generated at the lance (e) and rectified by the diode (b) is higher than the voltage that is going to be charged to the capacitor (c) from the opposite side. Of course you can keep it. In this way, the DC outputs are combined, and this state is as shown in FIG. That is, VCl is the voltage rectified from the AC output, and VO2 is the DC output voltage generated and rectified on the DC transformer (E) side. For the rated DC output, the output variable range VC2 has a fluctuation range centered around the rated DC output, but this output variable range VC2 is a total of input voltage fluctuations, load fluctuations, and AC output side fluctuations. The variation is set to be larger than the range of VC3.

Thus, the output variable range VC2 is used to vary the DC output and at the same time to compensate for fluctuations in the DC output.

Usually, the DC output of this type of transformer is designed to vary the output voltage in order to compensate for variations in copying conditions. The actual range of this variable voltage is ±10%, i.e., 1000~1100. It is about V. This means that VO2 of 1000 to 1100 V is sufficient.
The secondary winding of the DC transformer (a) is 750~8oov, 8
This means that it is only necessary to generate Also, the input voltage and load fluctuated. 9. With respect to fluctuations in the DC output caused by varying the AC output, the fluctuation in this type of transformer is usually within a range that is well within VO2, and is narrower than the width of VO2.

In addition, the DC output is divided by a resistor (T) and a variable resistor 0, which also serves as an output variable, to obtain a negative feedback signal, which is then
) Since the feedback circuit 0'4 is used to feed back to the control circuit section α on the Lance (E) side, all output fluctuations including DC output fluctuation factors due to AC output fluctuations can be dealt with on the DC transformer side. A device on the DC lance side that operates in this manner can be significantly miniaturized compared to a conventional device in which the entire DC output is obtained from a separate DC transformer. In other words, the core of the oscillation transformer was conventionally a KI 40 type ferrite core (the width of the core was 40 tranO).
The EI 19 type ferrite core improves the
The output capacitance of the oscillation transistor can also be reduced to one-fifth or less of that of the conventional one, allowing for miniaturization. Also,
Conventionally, output rectifier circuits used diodes and smoothing capacitors for high voltage applications, but the one shown in Figure 2 requires only medium voltage specifications or lower, allowing the use of small components. Therefore, conventionally,
All of the DC output is derived from a separate DC transformer. 7 bodies compared to i. It was about %. There is.

In addition, when considering the entire device, although the capacitor (C) has a slightly larger capacity than the conventional one, the voltage can be reduced from the conventional one of about 8 to 10 KV to 5 to 6 KV. Therefore, it does not become a factor for increasing the size in total.

Next, explanation will be given based on FIG. First, since a single-stone sine wave inverter is used on the AC transformer α°/l side, there is no DC output (when looking only at the AC output, the waveform is almost a sine wave. However, the waveform is 1
An imbalance of positive and negative arises, which can be called the destiny of the stone ceremony. That is, a difference occurs between Veop on the + side and VeOP on the one side. This depends on the Q of the oscillation circuit, but when the output is 5KvwL8, the output is about 50 to 100V. This unbalance can be easily changed to positive or negative by changing the connection method of the primary and secondary windings. Then, the highly unbalanced waveform side is connected to the polarity side supplied to the DC output. In this way, the highly unbalanced portion of the DC output is absorbed, the unbalance of the AC output is eliminated, and a positive/negative symmetrical waveform is obtained, resulting in a more favorable operation for the copying machine. That is, the paper can be smoothly peeled off from the photoreceptor drum, and there is no residual charge on the photoreceptor drum due to waveform imbalance, which improves the copy process operation.

Furthermore, although conventional output waveforms were unbalanced, the difference becomes a direct current component on the negative side, increasing the input voltage and reducing efficiency. However, if the positive and negative waveforms are made symmetrical by the above-mentioned means, this will disappear, the increase in DC output VA will be minimized, and the overall efficiency will increase.

Next, the modified tarp of the present invention will be explained based on FIGS. 5 and 6. Components that are the same as those described with reference to FIG. 2 are designated by the same reference numerals, and description thereof will be omitted. In this example,
A capacitor (C) is connected to the AC terminal 91) of the secondary winding of the AC transformer α and the opposite pole through a diode (C) on the DC lance (A) side. A series circuit of a resistor (b), a variable resistor (c), and a resistor OQ is connected in parallel with this capacitor 0→, and feedback is fed back from the variable resistor (to) to the control circuit section α. Also, AC terminal? A resistor 0η (b) is connected to the opposite side, a diode (a) and a capacitor ■ are connected to the middle point of these connections, and a resistor Kl) and a variable resistor (6) are connected to the capacitor α. , is fed back from this variable resistor (6) to the control circuit section α→.

Such a configuration is used when applying a DC nodal force to an AC output waveform. Depending on the type of copying machine, some copying machines apply a DC bias to the AC output to more smoothly separate the copy paper from the photosensitive drum. This circuit corresponds to this, and VOPΦ-Vope in the AC output waveform diagram shown in Figure 6 is D.
This is a DC bias using a C transformer.

The present invention provides an AC lance and a DC transformer, each connected to a control circuit including an oscillation circuit, in the same housing as described above, and converts the output of the AC lance into an AC output. Since the rectified signal and the output of the DC transformer are combined to produce a DC output, power consumption is low, input/output conversion efficiency is high, and other parts for rectification can be small, and the durability of the variable resistor is particularly improved. It is possible to use the device in a state where the temperature is high, and in this way, it is possible to form a highly reliable device with a reasonable design and an extremely small size.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of the conventional technology, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a graph showing the contents of DC output, Fig. 4 is a waveform diagram of AC output, FIG. 5 is a circuit diagram showing a modified example, and FIG. 6 is a waveform diagram of AC output. 16... Control circuit section, 17... AC) lance, 19
...Control circuit section, 20...DC transformer, 32...
・For feedback circuit Request person Tokyo Electric Co., Ltd. - Figure 3■ Nomo 5 Ugly

Claims (1)

[Scope of Claims] 1. A to which control circuit sections including oscillation circuits are respectively connected
A C transformer and a DC transformer are provided in the same housing, and the output of the AC transformer is set as an AC output, and the
A high-voltage power supply device characterized in that a rectified C output is combined with the output of the DC transformer to obtain a DC output. 2. The high-voltage power supply device according to claim 1, characterized in that a monolithic sine wave inverter is connected to an AC transformer to obtain an AC output. 3.A to which the control circuit section including the oscillation circuit is connected
C) A lance and a DC transformer are provided in the same housing, and the output of the AC) lance is made into an A (U output), and the rectified AC output is combined with the output of the DC transformer to produce a DC output. The output of the DC transformer is responsible for the output voltage variable range of the DC output, and this output voltage variable range is larger than the total variation of input voltage variation, load variation, and AC output side variation. 4. An AC lance and a DC transformer, each connected to a control circuit including an oscillation circuit, are provided in the same housing, and the output of the AC transformer is In addition to producing an AC output, the rectified AC output is combined with the output of the DC transformer to produce a DC output, and a feedback signal including the rectified value of the AC output is given to a control circuit section on the DC transformer side. A high-voltage power supply device comprising a feedback circuit that controls an oscillation transistor and stabilizes DC output. 5. An AC lance and a DC lance each connected to a control circuit including an oscillation circuit are provided in the same housing, and the output of the AC lance is an AC output, and this AC output is rectified. The output of the DC transformer is synthesized to form a DC output, and the AC output waveform balance is VOP.
A high voltage power supply device whose characteristic is that the higher polarity is set to be the load supply side of the DC output. 6.A to which the control circuit section including the oscillation circuit is connected
C) A lance and a DC transformer are provided in the same housing, and the output of the AC) lance is made into an AC output, and this A.
A high-voltage power supply characterized in that the rectified C output and the output of the DC transformer are combined to obtain a DC output, and the DC output waveform is added to the AC output waveform to obtain an AC waveform with a DC bias added. Device.