JPS62265678A - Image forming device capable of varying output of high voltage power supply - Google Patents

Abstract

PURPOSE:To steplessly change a high voltage output and to reduce the number of signal lines for high voltage output control by processing an output setting signal as an analog signal and changing the analog signal. CONSTITUTION:A using time signal, a photosensitive drum sensitivity signal, a photosensitive drum peripheral temperature signal, an original density signal, etc., are processed by a processing part 2 and a high voltage output setting signal (a) for applying optimum and uniform electrostatic charge attaining high picture quality corresponding to respective conditions to the photosensitive body is inputted to a high voltage power supply 4 through a D/A converter 3. The power supply 4 is provided with a pulse width modulating circuit 5 for inputting an output setting signal Vi and a switching element 6 to be driven by an output pulse and a required high voltage output Vo is obtained from a DC/DC converter 7 by switching the element 6. A part of the output Vo is fed back to an error amplifier 9 through a feedback circuit 8, so that the output Vo becomes a voltage faithful to the signal Vi.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image forming apparatus such as a copying machine that is equipped with a high voltage power source for charging a photoreceptor, and particularly relates to an image forming apparatus such as a copying machine that is equipped with a high voltage power source for charging a photoconductor, and in particular, an image forming apparatus that is capable of changing the high voltage power source steplessly. The present invention relates to an image forming apparatus.

[Prior art]

In a copying machine, a high-voltage power supply for charging a photoreceptor is configured so that its output voltage or output current can be switched in stages according to an external signal.

Due to the temperature characteristics of the photoreceptor, when the ambient temperature rises by α℃ above room temperature, the charge ``Is'' and the charge will decrease by β%, so the output of the high-voltage power supply is increased and controlled to achieve the desired amount of charge. In addition, as humidity, document density, photoconductor sensitivity, usage time (photoconductor deterioration), etc. become clearer, process conditions need to be controlled more precisely by combining various parameters to achieve higher image quality. It is becoming increasingly common to obtain images of

As a means for this purpose, changes in the various parameters described above are detected by a sensor, and according to the changes, as shown in FIG.
The high voltage output of the high voltage power supply 1 is changed by making it possible to select one of the control terminals for the ep3 output or the like to enable switching in several stages.

However, this method requires the number of signal lines for control according to the number of switching stages, and has the drawback of increasing costs due to the number of parts in the circuit configuration, ease of assembly, etc. as the number of switching stages increases.

Therefore, in order to reduce the number of signal lines, it is possible to use a decoder to obtain, for example, 23=8 types of signals with three signal lines, but if the number of switching stages further increases, the same signal will be generated as described above. The number of books will increase.

[Purpose of the invention]

An object of the present invention is to provide an image forming apparatus that can control high voltage output with a small number of control lines and solves the above-mentioned problems.

[Structure of the invention]

To this end, the present invention provides an image forming apparatus equipped with a high-voltage power source for charging a photoreceptor, in which the output of the high-voltage power source can be changed steplessly, and the output can be changed in response to changes in ambient temperature, document density, etc. It was configured so that the output could be continuously varied.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a diagram showing one embodiment thereof. Reference numeral 2 denotes a processing section consisting of a computer, into which a usage time signal, a sensitivity signal of the photoconductor drum, an ambient temperature signal of the photoconductor drum, a document density signal, etc. are inputted from predetermined sensors. There is. Then, in this processing section 2, each of the above signals is processed,
The high voltage output setting signal a for giving the photoreceptor an optimal uniform charge that can achieve high image quality corresponding to each of the above conditions is
The signal is converted into an analog signal by the D/A converter 3 and inputted to the high voltage power supply 4.

Assuming that the analog setting signal output from this D/A converter 3 is Vi, this output setting signal Vi and the high voltage output voltage V
If o is in the relationship Vo±k·Vi, by changing this output setting signal Vi, the output voltage Vo will change accordingly. Moreover, the output voltage Vo can be set steplessly and arbitrarily.

However, there are cases where Vo and Vi cannot maintain a simple proportional relationship. Therefore, in such a case, the required high-voltage output Vo is calculated using a computing unit that stores the relationship between vO and Vi.
The setting signal a is preliminarily processed by the processing unit 2, and the setting signal Vi obtained by D/A converting the control signal a is input to the high voltage power supply 4 so as to obtain the following.

The output 0N10FF signal vb outputted from the processing section 2 is for converting the output of the high voltage power supply 4 to 0N10FF.

FIG. 2 is a diagram showing an example of a high voltage power supply. In this example,
The main part of the control section is composed of a pulse width modulation circuit 5 that inputs an output setting signal Vi, and a switching element 6 that switches according to the output pulse of the pulse width modulation circuit 5. /expression-
The desired high voltage output is obtained from the motor 7. Note that a part of this output Vo is fed back to the error amplifier 9 via the feedback circuit 8, so that the output Vo becomes a voltage faithful to the output setting signal Vi. Reference numeral 10 denotes a switch circuit, which functions to switch the supply of input power Va to 0N10FF in response to an output 0N10FF switching signal vb.

〔Effect of the invention〕

From the above, according to the copying machine of the present invention, since the output setting signal is treated as an analog signal and is changed, the high voltage output can be changed steplessly, and the high voltage output can be controlled. The number of signal lines will be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of the copying machine of the present invention, and FIG.
The figure is a circuit diagram showing the internal circuit of the high-voltage power supply, and FIG. 3 is an explanatory diagram of the conventional high-voltage power supply. Agent Patent Attorney Tsune Nagao Akitaka FLhwa Figure 2

Claims (1)

[Claims] (1) In an image forming apparatus equipped with a high-voltage power source for charging a photoreceptor, the output of the high-voltage power source can be changed steplessly, and the output is continuously changed in response to changes in ambient temperature, changes in document density, etc. An image forming apparatus characterized by being able to change.