JPS5945473A - Ac power source device for copying machine - Google Patents

Abstract

PURPOSE:To enable the exact correction of an electric discharge characteristic even when electric discharge conditions fluctuate, by forming a titled device in such a way that the DC bias voltage superposed on the output of the AC power source can be controlled to both positive and negative directions. CONSTITUTION:A pair of diodes 24a, 24b connected via an adjusting resistor 26 to the low voltage tap terminal of a high voltage transformer 22 are connected reverse and a capacitor 28 (forming a passage for DC bias current) of which the other terminal is grounded is connected to the low voltage terminal of the transformer 22. A split value is adjusted by splitting the resistance 26 with a grounding terminal 26a. Then the DC bias voltage is regulated in both positive and negative directions and therefore even when the discharge conditions fluctuate, the discharge characteristic is corrected exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC power supply device for a copying machine that corrects fluctuations in discharge conditions by adjusting a DC bias voltage in both positive and negative directions.

For example, there is an AC power supply device for a copying machine as shown in FIG. .0 μA)f: Please note that the above-mentioned boosted voltage is received from the power supply 21 via the transformer 22 having a low voltage tap 22a of several 100 volts.

The power source 21 is connected to a switch 23'ffi'l [which is controlled by a microcomputer 12, which will be described later], and a low voltage tag 22a.
is connected to a half-wave rectifier circuit composed of a diode 24 and a capacitor 25, and an adjustment resistor 26 for adjusting the DC bias voltage is connected in parallel with the capacitor 25. The adjustment resistor 26 is connected to the sliding ground terminal 26 by the microcomputer 12GC.
It has a configuration in which the sliding of a is controlled, and the charging voltage of the capacitor 25 is divided into terminal voltages of the DC bias voltage capacitor 27.

The copying machine has a console 1 at the top, which is equipped with a tray 3 on which a document 2 is placed, various keys, switches, a copy count display, etc., and has a scanning system 4 for scanning the document and a photosensitive drum 5 inside. . Around the photosensitive drum 5 are a charging corotron 6, an exposure slit 8, a developing section 7, and a transfer corotron 13.
, a cleaning section 9 is provided, and the above-mentioned peeling corotron 20 is provided immediately after the transfer corotron 13. Copy paper is supplied from paper feed trays 10a and 10b, transferred by a transfer corotron 13, peeled off by a peeling corotron 20, fixed in a fixing section 11, and then discharged.

The copying machine described above has an input/output interface 12a.

12 e SROM 12 b, RAM 12 c
, and its operation is controlled by a microcomputer 12 having a CPU 12d.

In the configuration of the AC power supply device described above, the copy paper is charged with a polarity opposite to that of the developing toner on the photoreceptor drum 5 by the DC discharge of the transfer corotron 13 and transferred, and then the copy paper is transferred by the AC discharge of the peeling corotron 20. The static electricity is removed (middle o [1)]. The copy paper is peeled off by this separation 11, and after being peeled off, it is transferred to the fixed arm portion 11. At this time, by adjusting the adjustment resistor 8, the DC bias voltage (9 of the capacitor 27; 1h'!i
Control the pressure (pressure) and set the optimal peeling conditions for peeling! 1.
We are aiming for the direction of J' nature. In other words, as shown in FIG. 2, the discharge current value (curve a) based on the positive voltage and the negative 'i
li, the general % nature of AC discharge in which the level of the discharge current value (curve b) based on the pressure is different, and the asymmetry of the discharge current based on the positive/negative of this discharge voltage are also subject to certain conditions (ambient temperature and humidity, In order to correct the Group 11L characteristics that vary based on variations in the diameter of the wire, changes in its surface, distance from the photoreceptor drum, etc., the DC bias voltage described in tiiJ is controlled.

However, according to this AC power supply device Jf,l, the diode
G24 Since the half-wave rectified DC voltage of the half-wave rectifier circuit consisting of the capacitor 25 is divided by the adjustment resistor 25 and used as the DC bias voltage, as shown in FIGS. The bias voltage is shifted by VB in (a) (VAC is the AC discharge voltage), and the bias voltage cannot be controlled outside the range from zero to the positive value VB determined by the low voltage tap 22a and the half-wave rectifier circuit. (Cannot be controlled in the negative direction near zero level).

The present invention has been made in view of the above, and in order to be able to control the DC bias voltage in both positive and negative directions, it is possible to control the DC bias voltage in both positive and negative directions. A pair of diodes are connected in opposite directions, a capacitor (forming a path for direct current bias current) whose other end is grounded is fully connected to the low voltage end of the high voltage transformer, and the adjustment resistor is divided by the ground terminal. An object of the present invention is to provide an AC power supply device for a copying machine in which the division value is adjusted.

The AC power supply device for a copying machine according to the present invention will be explained in detail below.

FIG. 4 shows an embodiment of the present invention, and parts that are the same as those in FIG. A pair of diodes 24a and 24b are connected to diodes 22a in opposite directions, and the other end is connected via an adjustment resistor 26. The adjusting resistor 26 is slid by a sliding grounding terminal ρ11.1 26a which is adjusted by the output of the microcomputer 12, and a capacitor 28 is connected to the low voltage end of the transformer 22, and the other end of the capacitor 28 is grounded. The discharge voltage applied from the transformer 22 to the peeling corotron 20 is 3 to 5 k'V (frequency is several 100 hertz, discharged current is several 100 to 2000 μA),
Low pressure tap 22a & 100v. In addition, the adjustment resistor 26 is in the order of hundreds of Ω to the capacitor 28 [
0,01~0,1,/IF and exfoliated corotron 2
It forms a discharge current branch that flows to 0 and peels off)'jI
The DC component of the discharge current of the L corotron 20 is blocked.

To explain the operation of the above 414 configuration, when the adjustment resistor 26 is slid to the anode side of the diode 24a, the position of the grounding terminal 26a is pushed to the anode side of the diode 24a. The DC bias voltage vB1 is determined, and when the diode 24b is slid to the cathode side, the half-wave rectification action of the diode 24b and the capacitor 28 determines the DC bias voltage ■B2. DC bias voltage vB3 is determined according to the position of . Figure 5 shows this DC bias voltage v, 1 1 VB2
t VB3 All 3 together show the discharge characteristic curve C of the exfoliated corotron 20 (in the figure, VB is the DC bias voltage, and DC is the DC bias current). Therefore,
Discharge characteristic curve C and DC bias voltage VBs + V
B2 + VBs (7) DC bias currents ioc based on the intersections PITP2TP3 are obtained.

FIG. 6(A) shows the AC discharge voltage VAC and the DC bias voltage vBl r VB2f that bias-controls it, FIG. 6(B) shows the AC discharge voltage VAC superimposed on the positive DC bias voltage VBI, and FIG. Figure 6 shows the AC discharge voltage vAC on which the negative DC bias voltage vB is superimposed.

Oka: In the above embodiment, an impedance for current detection may be inserted at point C1 or C2 of the DC power supply device in FIG. may be inserted. In addition, the above actual l
In the Ai example, the entire AC voltage is supplied to the peeling corotron 20, but the application is not limited to this.

As explained above, according to the countercurrent power supply device δ for a copying machine according to the present invention, a pair of diodes connected to the low voltage tap terminal of a voltage transformer via an adjustment resistor are connected in opposite directions. and a capacitor (forming a path for direct current bias current) whose other end is grounded is connected to the low voltage end of the high-voltage transformer, and the adjustment resistor is divided by the ground terminal to adjust the division value. Therefore, the DC bias voltage that is multiplied by M to the AC power supply output can be controlled in both positive and negative directions.Therefore, even if the discharge conditions change, the discharge characteristics can be accurately corrected.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional main flow power supply device for a copying machine. FIG. 2 is a discharge characteristic diagram of a discharger for a copying machine. FIGS. 3A and 3B are explanatory diagrams showing conventional control of a DC bias value of an AC discharge voltage. FIG. 4 is an explanatory diagram showing one embodiment of the present invention. FIG. 5 is an explanatory diagram showing the relationship between DC bias voltage and DC bias current of the present invention. Figure 6 (a), (
B) and (C) are explanatory diagrams showing DC bias value control of AC discharge voltage according to the present invention. Explanation of symbols 1...console, 2...manuscript, 3...
platen, 4... scanning system, 5... photosensitive drum,
6... Charger, 7... Developing section, 8... Exposure section, 9... Cleaning section, 10a, 10b... Paper feed tray, 11... Fixing section, 12... Microcomputer , 13... Transfer corotron, 20... Peeling corotron, 21... AC power supply, 22... High voltage transformer, 23... Power switch, 24+2
4a+24b”・Evening” Iode, 25, 27.28
...Capacitor, 26 adjustment resistor, 261L...Sliding ground terminal. 4

Claims (1)

[Claims] A high-voltage transformer that outputs an AC discharge voltage from one end to a discharge section for a copying machine; a pair of rectifying members connected to the grounding member; a grounding member that divides and grounds the adjustment resistor at dividing points corresponding to the level of the DC bias voltage; and a pair of rectifying members and the grounding member connected to the other end of the high voltage transformer. 1. An AC power supply device for a copying machine, comprising: a DC bias voltage capacitor that cooperates with the DC bias voltage capacitor to form a DC bias current path.