JPS6338714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a static elimination operation performed prior to cleaning untransferred toner remaining on a photoreceptor.

Generally, in an electrophotographic apparatus, in order to effectively remove untransferred toner remaining on a photoreceptor, a static eliminating charger is disposed in front of a cleaning unit consisting of a fur brush or the like.

By the way, in general, when the density of the image to be cleaned is high, the corona discharge current before cleaning, that is, the drum current value of the static elimination charger before cleaning, must be larger than when the density of the image to be cleaned is low. , to prevent cleaning failures from occurring regardless of the residual toner concentration, the current value should be set to
It is necessary to set it to a level when the density of the image to be cleaned is high.

However, if the drum current value of the static elimination charger before cleaning is always set at a high level, the electrostatic properties of the photoreceptor made of photoconductive material tend to deteriorate, making it difficult to ensure good image formation over a long period of time. There is a problem that makes it impossible to do so.

In view of these problems, the present invention proposes a new static elimination method that can always ensure good cleaning performance for untransferred residual toner of any density without impairing the durability of the photoreceptor. The purpose of this device is to provide an electrophotographic apparatus equipped with a static eliminator in front of a cleaning device, in which the current supplied to the static eliminator remains on the electrostatic image bearing device. A control method is provided in which the concentration of charged colored fine particles is controlled by an output signal of a detection means for detecting the amount of light reflection.

Therefore, the details of the present invention will be explained below based on examples.

FIG. 1 shows the main parts of a copying machine to which the present invention is applied. 1 is a photoreceptor drum that serves as an electrostatic image carrier; 2 is a photoreceptor drum that undergoes charging, exposure, and development processes; The toner image formed on the transfer paper 3
a transfer charger for electrostatic transfer onto
Reference numeral 4 designates a static elimination charger that charges the untransferred toner on the photosensitive drum 1 with a polarity opposite to that of the toner, and 5 designates a cleaning unit disposed behind the static elimination charger 4. Reference numeral 6 in the figure indicates a toner density detector using an element such as a phototransistor, which detects the density of untransferred toner remaining on the photosensitive drum 1 in front of the cleaning unit 5.
It outputs a signal according to the toner density.
A control circuit 7 disposed between the static elimination charger 4 and the high voltage power supply 8 includes the toner concentration detector 6
It is configured to control the current supplied to the static elimination charger 4 with a detection output of .

Therefore, according to this embodiment, the current supplied to the static elimination charger 4 is always controlled to an appropriate amount according to the concentration of untransferred toner directly detected by the toner concentration detector 6. Become.

As described above, according to the present invention, the concentration of charged colored fine particles remaining on the electrostatic image carrier is detected as the amount of light reflection, and the current supplied to the static elimination charger is controlled based on this detection signal. , it is possible to effectively eliminate static electricity without causing fatigue to the electrostatic image bearing member, and it is possible to maintain good image formation at all times, and at the same time, it is possible to significantly reduce power consumption.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a copying machine to which the present invention is applied. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Transfer charger, 4... Static elimination charger, 5... Cleaning unit, 6... Toner density detector, 7... Control circuit.

Claims (1)

[Claims] 1. In an electrophotographic apparatus comprising a static elimination charger in front of the cleaning means, a detection means detects the concentration of charged colored fine particles remaining on the electrostatic image bearing means as the amount of light reflection by the current supplied to the static elimination charger. A method of controlling a static elimination charger by controlling an output signal of the charger.