JPH0733247Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus in a xerographic type image forming apparatus in which creeping leakage of a corotron insulator block is prevented.

(Prior Art) A device around a photoconductor in a conventional xerographic image forming apparatus will be described with reference to FIG.

As shown in the drawing, in the periphery of the photoconductor 1, a charging corotron 2 for uniformly charging the photoconductor, and for irradiating the uniformly charged photoconductor 1 with light according to image information. An LED (light emitting diode) array 3 for forming an electrostatic latent image and a developing device 4 for developing the electrostatic latent image formed on the photoconductor 1 are arranged.

The recording paper is conveyed from the chute 5 toward the photoconductor 1 at an appropriate timing, and the electrostatic latent image developed by the developing device 4 is transferred to the recording paper by the action of the transfer corotron 6. Next, the recording paper is peeled off from the photoconductor 1 by the action of the peeling corotron 7 and conveyed to a fixing device (not shown). After that, the residual toner adhering to the photoconductor 1 is removed by the cleaner 8 and again uniformly charged by the charging corotron 2.

The transfer and peeling corotrons 6 and 7 are supplied with high-voltage alternating currents g and h from a high-voltage power supply 9.

The structure of the transfer and peeling corotrons 6 and 7 will be described with reference to FIG. This figure shows a front view of the transfer and release corotrons 6, 7. The shield 10 has a length substantially the same as the length of the photoreceptor 1 in the central axis direction, and is provided with a partition plate 11 extending in the length direction at the center thereof. Insulator blocks 12a and 12b having a thickness of about half the depth of the shield 10 are fixed to both ends of the shield 10. Corotron wires 13a and 13b are stretched over the insulator blocks 12a and 12b so as to be parallel to each other in two regions separated by the partition plate 11.
One ends of the two corotron wires 13a and 13b are electrically connected to the electrodes 14a and 14b, respectively.

(Problems to be Solved by the Invention) Conventionally, the high-voltage power source 9 to the two corotron wires
High voltage alternating currents g and h as shown in FIG. 9 were applied to 13a and 13b. That is, the phase is almost 180 °
Different alternating currents g and h were being applied. As a result, as shown by the double-headed arrow in FIG. 9, both alternating current g,
When the potential difference of h becomes maximum, a creeping current flows on the surfaces of the insulator blocks 12a, 12b, and the dielectric breakdown of the surfaces of the insulator blocks 12a, 12b gradually progresses. Finally, there is a problem that a conductive path may be formed between the corotron wires 13a and 13b on the insulator block 12a or 12b and short circuit may occur.

Moreover, there was a problem with safety.

An object of the present invention is to eliminate the problems of the conventional device and to provide an insulator block for the transfer and peeling corotron.
An object of the present invention is to provide a safe and long-life image forming apparatus in which there is no fear that the surface of 12a, 12b will be short-circuited due to dielectric breakdown.

(Means and Actions for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a high-voltage power supply device that creates two high-voltage AC outputs of substantially the same phase, and transfers a xerographic image forming apparatus Also, it is characterized in that a high-voltage alternating current of substantially the same phase is supplied to the wire of the stripping corotron from the high-voltage power supply device.

According to the present invention, since the potential difference between the wires of the transfer and peeling corotron does not become large, there is no fear that a creeping current will flow on the surface of the insulator block of the corotron to cause dielectric breakdown.

Therefore, it is possible to provide a safe and long-life image forming apparatus.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of a high voltage power supply device according to an embodiment of the present invention.

In the figure, 6 and 7 are a transfer corotron and a peeling corotron similar to those in FIG. 7, respectively. Further, 21 is a sawtooth wave generator, and 22 and 23 are the first and the second, respectively.
A sawtooth wave a outputted from the sawtooth wave generator 21 and a control voltage b which is a constant voltage of a predetermined magnitude, to the first and second drive control circuits 22 and 23. Is typing.

The outputs c and d of the first drive control circuit 22 are respectively the first
And to the bases of the second transistors 24a and 24b. The collectors of the first and second transistors 24a and 24b are connected via the primary winding of the transformer 25, and the emitters of both are connected to each other.
The connection point of the emitter is grounded, and the power supply 26 is connected between the connection point and the middle point of the primary winding. On the other hand, a capacitor is connected to both ends of the secondary winding of the transformer 25, one end of which is grounded, and the other end is connected to the corotron wire 13a of the transfer corotron 6 via a resistor. As a result, the corotron wire of the transfer corotron 6
A high voltage AC g is supplied to 13a.

The outputs e and f of the second drive control circuit 23 are also connected to the same circuits as the circuits of the outputs c and d of the first drive control circuit 22. That is, the third and fourth transistors 27
Connected to the bases of a and 27b. The collectors of the third and fourth transistors 27a and 27b are transformers 28
Are connected to each other via their primary windings, and their emitters are connected to each other. The connection point of the emitter is grounded, and the power supply 29 is connected between the connection point and the middle point of the primary winding.
Are connected. On the other hand, a capacitor is connected to both ends of the secondary winding of the transformer 28, one end of which is grounded, and the other end of which is connected through a resistor to the corotron wire of the peeling corotron 7.
It is connected to 13b. As a result, the peeling corotron 7
The high voltage alternating current h is supplied to the corotron wire 12b.

Next, the operation of this embodiment will be described with reference to FIG. 1 and FIG. Here, FIG. 2 shows a waveform diagram of signals having the same reference numerals in FIG.

Now, when the sawtooth wave a output from the sawtooth wave generator 21 and the control voltage b of a constant voltage are applied to the first and second drive control circuits 22 and 23, the first and second drive control circuits are applied. The circuits 22 and 23 output rectangular waves having the waveforms shown in c, d and e, f of FIG. The rectangular waves c and e have the same waveform, and the rectangular waves d and f have the same waveform. Also,
The rectangular waves c and e, and the rectangular waves d and f have phases of 18 relative to each other.
0 ° different.

When the signals c and e output from the first and second drive control circuits 22 and 23 are applied to the bases of the first and third transistors 24a and 27a to make them conductive, the primary windings of the transformers 25 and 28 become Current flows in the upper half, and positive voltages g and h having the same phase are generated in the respective secondary windings. Next, when the signals d and f are applied to the bases of the second and fourth transistors 24b and 27b to make them conductive, a reverse current flows in the lower half of the primary windings of the transformers 25 and 28, and their secondary windings. In-phase negative voltages g and h are generated on each of the lines.

According to the present embodiment, the above operation is repeated and the second operation is performed.
A high voltage alternating current having a waveform shown in g and h of the figure is applied to the transfer and peeling corotrons 6 and 7.

Therefore, a large electric potential difference does not occur between the wires of the insulator blocks 12a and 12b of the corotron described in FIG. 8, and a creeping current does not flow on the surface of the block and dielectric breakdown does not occur.

FIG. 3 shows a specific example of the first and second drive control circuits 22 and 23. Further, FIG. 4 shows a waveform diagram of the signal.

In FIG. 3, 31 is a comparator, 32 is a flip-flop,
33 and 34 are Noah circuits. When the sawtooth wave a and the control voltage b are input to the comparator 31, they are compared in magnitude, and a negative signal is output when the former is larger than the latter and a positive signal i is output when the former is smaller. The signal i is a flip-flop 32,
Input to one of the input terminals of the NOR circuits 33 and 34. The flip-flop 32 is triggered by the rising edge of the signal i and outputs a signal k that is 180 ° out of phase with the signal j. When the NOR logic of the signal j and the signal i is taken by the NOR circuit 33, the signal c is obtained. On the other hand, when the NOR logic of the signal k and the signal i is taken by the NOR circuit 34, the signal d
Is obtained.

As described above, the first and second drive control circuits
The signals c and d having the above-mentioned waveforms are obtained from 22 and 23.

FIG. 5 shows a second embodiment of the present invention. This embodiment is the first
The difference from the embodiment is that the primary side of the transformer 40 is composed of a set of drive control circuits 41, first and second transistors 42 and 43, and a power supply 44.

Also in this embodiment, the waveforms of the signals a to h in the figure are the second
Signals g and h having the same phases as those of the corresponding symbols in the figure and having the same phase are applied to the transfer and peeling corotrons 6 and 7. Therefore, a large potential difference does not occur between the corotron wires of the insulator blocks 12a and 12b of the corotron described in FIG. 8, and a creeping current does not flow on the surface of the block to cause dielectric breakdown.

FIG. 6 shows a third embodiment of the present invention. The difference of this embodiment from FIG. 5 is that the secondary side of the transformer 40 is composed of one winding, and the high voltage AC for the peeling corotron 7 is taken out from the middle of the secondary winding.

Also in this embodiment, the waveforms of the signals a to h in the figure are the second
It will be apparent that the high voltage alternating currents g and h, which have the same signal waveforms as the corresponding symbols in the figure and have the same phase, are applied to the transfer and peeling corotrons 6, 7.

Although the present invention has been described with reference to the embodiments, it is apparent that the present invention is not limited to this. In short,
It goes without saying that if the phase of the high-voltage alternating current applied to the transfer and peeling corotrons 6 and 7 is in-phase or close to that, it falls within the scope of the present invention.

(Effect of the Invention) According to the present invention, since the phase of the high-voltage alternating current applied to the transfer and peeling corotron becomes in-phase or close to that, a large potential difference is generated between the corotron wires of the insulator block of the corotron. As a result, a creeping current does not flow on the surface of the block to cause dielectric breakdown.
Therefore, there is no fear that a conductive path will be formed between the corotron wires and short-circuited, and it is possible to provide a safe and long-life image forming apparatus.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention, and FIG. 2 is a circuit diagram of the first embodiment.
FIG. 3 is a circuit diagram showing a concrete example of the drive control circuit shown in FIG. 1, and FIG.
5 and 6 are circuit diagrams of the second and third embodiments of the present invention, respectively, and FIG. 7 is a diagram of a device around the photoconductor of a conventional xerographic image forming apparatus. A schematic view, FIG. 8 is a front view of the transfer and peeling corotron, and FIG. 9 is a waveform diagram of a signal applied to a wire of the transfer and peeling corotron. 6 ... Transfer corotron, 7 ... Peeling corotron, 21 ... Sawtooth wave generator, 22, 23 ... First and second drive control circuits, 24
a, 24b, 27a, 27b ... Transistor, 25, 28 ... Transformer

Claims (1)

[Scope of utility model registration request] 1. In a xerographic image forming apparatus having a transfer and peeling corotron formed by stretching two wires in parallel between at least two insulator blocks, a phase difference of 180 ° from each other is controlled. A drive control unit that outputs a signal, at least two switching units that are turned on and off by the control signal, and two substantially in-phase boosted from currents that are turned on and off by the two switching units. And a high-voltage alternating current generating means for generating a high-voltage alternating current, and the two high-voltage alternating currents having substantially the same phase are supplied to the wires of the transfer and peeling corotrons, respectively.