JPS6035958A - Output controller of high voltage power source for copying machine - Google Patents

Abstract

PURPOSE:To obtain stable drum potential by determining either one load characteristic by utilizing the difference between the discharge starting voltage to a case and a discharge starting voltage to a drum, and calculating a drum current from the discharging currents. CONSTITUTION:A transistor 6 is switched by a pulse from a pulse width controller 5, and a high voltage pulse from the secondary side of a transformer 7 is rectified and smoothed by a diode 8 and a capacitor 9, thereby obtaining a high DC voltage. This output voltage is divided by resistors 10, 11, and inputted through an A/D converter 13 to an arithmetic unit 13. The output current is detected by a resistor 12, and inputted through an A/D converter 14 to an arithmetic unit 15. The unit 15 applies an output to a pulse width controller 5, thereby controlling so that the output becomes constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a high-voltage power supply for a copying machine connected to a charger that applies an electrostatic charge for forming a VP electric image on a photoreceptor, and particularly relates to a high-voltage power supply for a copying machine that is connected to a charger that applies an electrostatic charge for forming a VP electric image on a photoreceptor. An output control device is used to control and stabilize the surface potential on the photoreceptor.

(Prior Art Wi) Conventionally, as this type of control method, one is known in which a surface potential sensor is used and a high voltage power source is controlled based on this value. However, this method has the disadvantage that regular maintenance is required because errors occur due to dirt on the sensor, and the sensor is expensive and requires a storage space, making it impossible to make it compact and inexpensive.

A method is also known in which the charger case is insulated and the case current is detected, and the photoreceptor drum current is derived from the supplied current to control the high voltage power supply. /c The structure becomes complicated. Furthermore, an element and lead wires for detecting the case current are required, resulting in a more complicated configuration.

Furthermore, a method is also known in which the drum is insulated, the drum current is detected, and the output of the high voltage power supply is thereby controlled. In this method, the sound detection becomes complicated because the drum is insulated and the drum current is detected from here.Also, since multiple charge currents flow through the drum, it is difficult to measure the current for each drum. , a time difference is required between the respective charging currents, which has the disadvantage that control takes time.

(Purpose) In electronic reporting machines using an electrostatic process, stably controlling the amount of charge on the latent image forming member is the key to obtaining good copied images.

A widely used method is to apply a charge to the latent image forming member (hereinafter referred to as the drum) by using a high voltage power source, and by using corona discharge from a discharge electrode (hereinafter referred to as the charge wire) connected to this first.・It is being done.

However, when the discharge current is small, the corona discharge from the charge wire is non-uniform and cannot provide a uniform charge to the drum, resulting in unevenness in the copied image. Therefore, by configuring a case to surround the charge wire and diverting the discharge current to this case, the charge wire can be discharged.
It is good to increase the current and make the discharge uniform [! I'm trying to get it.

This method of using a case around the charge wire is a well-known technique, and it is unavoidable.

However, for this reason, the discharge current from the charge wire (hereinafter referred to as total current IT) is divided into a discharge current to the drum (hereinafter referred to as drum current ID) and a current flowing to the case (hereinafter referred to as nurse electric current 0).

However, the ratio of drum current to case current changes due to changes in the charge wire over time, humidity, atmospheric pressure, and other environmental changes, so even if the total current is controlled to be constant, these disturbances will cause each current to remain constant. do not have.

Since there is a Ni-2 relationship between the electric charge ff1Q and the electric current, it is sufficient to keep the electric current constant in order to keep the electric charge constant. In other words, in order to make the charge on the drum uniform, the drum current ID must be kept constant.

However, as mentioned above, In/Ia changes due to disturbance, and I
Even if F is kept constant, ID cannot be kept constant.

Therefore, the above-mentioned conventional techniques have been considered, but each requires modification of the copying machine itself, making it complicated and expensive.

The present invention was developed in view of these circumstances, and utilizes the difference between the discharge starting voltage to the case and the discharge starting voltage to the drum to determine the load characteristics of one of them, and to control the discharge. current,
The purpose is to obtain a stable drum potential by calculating the drum phase flow from

(Structure) First, let's look at the characteristics of corona discharge. The relationship between the current flow and the applied voltage V for Kopusuden 2 is 3V (v-vo).
(Formula 1) is derived by Townsen (K: ion mobility, P: atmospheric pressure, C: coefficient depending on the shape of the corona generator, etc., vo: discharge starting voltage). From this, it can be seen that the process changes depending on the atmospheric pressure and the condition of the copier generator. It is also known from experimental results that it changes depending on the surface condition of the wire, the surrounding humidity, and the distance from the electrode.

The charging section of the electronic copying machine will now be explained with reference to FIG.

When the output of the high voltage power supply 1 is connected to two charge wires, the current IT flowing through the charge wire 2 is the case room temperature 1o flowing to the case 3 and the drum current ID flowing to the drum 4.
Therefore, T, T −Io + ID (Formula 2) and 1c.

By the way, since the draft 4 and the case 3 are generally fixed to the metal structure of the copying machine, it is not possible to detect the current flowing therethrough.

Generally, the distance mta between the charge wire 2 and the case 3 shown in FIG.
There is also an inflection point at the point VD where discharge starts to the drum 4. Substituting the electric current 2 at one point VO2 between Va and the next inflection point into equation 1, the equation for the discharge current flowing only through nurse 3 is: Within a short time, the pressure P1 depends on the mobility. Coefficient G
Since it does not change, it is set as electric number A, -T-C.

Since the operation near the starting point of the discharge 1χ is unstable, a constant current 1. Equation 1 is solved by measuring the voltage Vσ1 when Vσ1 and the current ■ when at least one point VO2 up to the next inflection point.

Unknowns A and V. This can be solved because two equations exist with two pieces.

Act the value given to make it easier to understand.

'Va, then Io-Ao (V-Vo) (Formula 3). VTI discharged to both case 3 and drum 4
, VT217), the current I3 #I4 is calculated by 'fs', and equation 1 is solved in the same manner as CIa, then IT-At (V
-VT) (Equation 4). Substituting equations 3 and 4 into equation 2, the relationship between drum current and voltage at that time is ID-(AT-Ao
)V -ATLr4-AaVo (Formula 5) is true.

If we consider now that the drum current is α, then I of Equation 5 is
By substituting the factor α into D, the high voltage power supply can be controlled so that the voltage at this time is V-. Alternatively, by substituting this into equation 4, it is also possible to find the IT or voltage at the time of the current ID flowing to the charger at that time.

FIG. 5 shows an example thereof. To explain this, a transistor 6 is switched using a pulse obtained by a pulse width controller 5, a high voltage pulse is taken out to the secondary side of a transformer 7, and this is rectified and smoothed by a diode 8 and a capacitor 9 to generate a DC high voltage. obtain.

This output voltage is divided by a resistor 10S resistor 11 and jL/D
Connected to converter 13. The output current is detected by a resistor 12 and similarly input to a KA/D converter 14. These A
The /D converters 13 and 14 are connected to the arithmetic unit 15.

Normally, only the output voltage or output current is taken as information,
A pulse width such that this value becomes the target value is calculated, and the signal is supplied to the pulse width controller 5 so that the pulse width is controlled to be constant.

゛When the test signal is received now, the arithmetic unit 15 supplies the pulse width controller 5 with a signal that gradually widens the pulse width. The output voltage and output current at this time are measured and stored in the memory of the computing unit 15. Using this data, the computing unit 15
By calculating I = A V (V - Vo ) and differentiating this, the inflection point is found. Calculate Io=AoV (V-Vo) from the data up to the first inflection point. Calculate IT-ATV (V-Vr) from the data after the next inflection point. And from these ATV (V-VT) -ID
Add +AOV (V - VO).

Next, substitute the drum current value α stored in advance and set it as the reference voltage for v7 at this time. ◇When a trigger signal is received here, normal operation will occur, and the output voltage will become this reference voltage. The control operation described above is performed.

Incidentally, here, the reference may be a current as well.

Further, although the pulse width controller 5 is provided separately from the arithmetic unit 15, it is easily possible to provide this function to the arithmetic unit 5.

It is also possible to perform test operations successively in each copy cycle without using the test signal.

Since warehouse characteristics can be managed, it is easy to detect deterioration of wires, deterioration of the environment, etc. and send this as a signal to the outside.

FIG. 3 is a characteristic diagram showing the relationship between these applied voltages and discharge current.

(Effects) The present invention is as described above, and according to the present invention, even if there are changes in the environment or changes over time, a single charge amount can be applied to the drum (electrostatic latent image forming member). Moreover, since there is no need to change the support structure of the drum or the charge case at all, it can be used as is in conventional copying machines. Furthermore, in order to measure the drum or charge case current, it is not necessary to insulate each drum or charge case and use a detection element therein, so it is possible to avoid an increase in size and cost, and there is no need for expensive equipment such as a surface potential sensor.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the relationship of the drum charger, FIG. 2 is a control pull diagram according to an embodiment of the present invention, and FIG. 3 is its output characteristic diagram. 1...High voltage 1 source, 2...Discharge electrode,
3... Nurse, 4... Drum, 13.
14...A as output current/output voltage detector
/D converter, 15... Arithmetic unit.

Claims (1)

[Scope of Claims] (1) A high-voltage power supply for a copying machine that applies a high voltage to a charger consisting of a discharge electrode and a nurse adjacent to the discharge electrode, comprising: an output voltage detector, an output current detector, and an output current detector; 1. An output control device for a high-voltage power supply for a copying machine, comprising a calculation unit that calculates a load condition and a controller that controls an output according to the calculation result. (2) An output control device for a high-voltage power supply for a copying machine as set forth in claim (1), comprising variable means for continuously or intermittently varying the output voltage or output current. (8) A copying machine according to claim (1), comprising an arithmetic unit that calculates the relationship between the discharge current and the discharge voltage from the respective output current and output voltage when the output is varied by the variable means. Output control device for high voltage power supply. (4) An output control device for a high-voltage power supply for a copying machine as set forth in claim (8), comprising an arithmetic unit that calculates an inflection point from the relationship between discharge current and discharge voltage. (5) Based on the relationship between the emitted γL current and the discharge voltage from the determined current to the next inflection point, the discharge relational expression from the discharge electrode to the case or from the discharge electrode to the electrostatic latent image creation member can be calculated. An output control device for a high-voltage power supply for a copying machine according to claim 1, which is equipped with an arithmetic unit for calculation. An operation for calculating the current flowing from the discharge electrode to the electrostatic latent image forming member based on the relationship when discharging to the electrostatic latent image forming member and the relational expression set in claim (5). An output control device for a high-voltage power supply for a copying machine as set forth in claim (1). Claim No. 3 for controlling the current (
14. The output control device for a high-voltage power supply for a copying machine according to item 13.