JPS61205962A - Contamination detecting mechanism for electrifying device - Google Patents

Abstract

PURPOSE:To detect the contamination of an electrified wire, and also to execute exactly its cleaning by constituting a titled mechanism so that the contamination of a discharge member is detected by detecting a variation of a voltage or a current applied to an electrifying device. CONSTITUTION:There are cases when a constant-current is used and a constant- voltage is used as a power source of a detecting mechanism. When using the constant-current, a constant-current power source 11 is connected to an electrifying device 2, and also a detecting circuit 12a for detecting a variation of a voltage applied to an electrifying wire being a discharge member of the electrifying device 2 through a resistance R1 and R2, by comparing it with a threshold value is connected. Also, this mechanism is constituted so that warning is displayed by making a prescribed light emitting diode, etc. emit light by a detecting signal 13 from the detecting circuit 12a, and also a recording operation is stopped temporarily. also, a controlling circuit 14 operates a cleaning device 15 of the electrifying wire by receiving the detecting signal 13. In this regard, in case of the constant-current power source, a detecting circuit 12b is not required.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for detecting contamination of a charging device that automatically detects contamination of a discharging member in a charging device used in electrophotography, etc., and warns of the contamination. It is about the mechanism.

<Prior art> Electrostatic recording devices, electrophotographic devices, etc. generally use a charging device that generates corona discharge from a charging wire. etc. adhere to the charging wire, and since the charging wire to which the substance has adhered is unevenly soiled, the discharge characteristics deteriorate, and furthermore, the characteristics of the created image deteriorate. Therefore, in the electrophotographic recording apparatus and the like, dirt on the charging wire must be detected and removed in a timely manner.

Conventionally, the method for detecting the above-mentioned stains is to count the number of images created and detect it when the number of images reaches a certain number, since the relationship between the number of images created and the dirt on the charging wire is proportional to some extent. The conventional methods include cleaning the wires by using the wires, or cleaning the wires at regular intervals during normal use.

<Problems to be Solved by the Invention> However, in reality, the number of images to be produced and the contamination of the charging wire differ depending on the usage conditions of the apparatus, and are not in a strictly proportional relationship.

Therefore, when detecting dirt on the charging wire using the conventional method described above, it may detect dirt on the charging wire even though it is actually hardly dirty, or may detect dirt on the charging wire even though it is dirty to the extent that the image becomes very dirty. There were problems such as wire stains not being detected and wire glue leaning not being performed.

The present invention is a completely new technology developed to solve the above-mentioned conventional problems, and its purpose is to appropriately detect dirt on the charging wire, warn about it, and also enable cleaning. The goal is to

Means for Solving the Problems> An embodiment for solving the above problems will be described in the case where it is applied to an electrophotographic apparatus with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a photoreceptor drum rotating in the direction of arrow a, the surface of which is uniformly charged by a primary charging device 2, and exposed by an exposure optical system 3 to form a photoreceptor on the surface of the drum 1. An electrostatic latent image is formed on the image forming apparatus 4, and is further developed into a visible image by a developing device 4. Further, the visible image passes through the pre-transfer charger 5 and then passes through the transfer 1 separation charger 6.
The image is then transferred onto the recording paper 8 that is conveyed by a rollerf. Thereafter, the toner remaining on the surface of the drum 1 is removed by a cleaning roller and a cleaning blade 9, and - before the next charging is performed, a pre-exposure is performed by a light emitting diode 10 for pre-exposure, and the charge remaining on the surface of the drum 1 is removed. is configured so that it is erased.

The above-mentioned secondary charging device 2 is provided with a mechanism for detecting contamination of the charging wire (not shown) which is a discharging member, and its power source may be either a constant current power source or a constant voltage power source. be.

Here, we will explain the case where a constant current power source is used. As shown in the drawing, a constant current power source 11 is connected to the charging device 2, and a charging wire, which is a discharging member of the charging device 2, is connected to the charging device 2 via a resistor R9 and a resistor Rt. The change in applied voltage is
A detection circuit 12a that performs detection by comparison with a threshold value is connected, and the detection signal 13 from the detection circuit 12a causes a predetermined light emitting diode or the like to emit light to display a warning and to temporarily stop the recording operation of the recording device. has been done.

Further, 14 is a control circuit which receives the detection signal 13 and operates a wire cleaning device 15 for the charging wire.

Incidentally, in the case of a constant current power supply as described above, the detection circuit 12b shown in the drawings is not necessary.

<Function> Next, in the above device, the function when the charging wire of the charging device 2 is dirty will be explained.

When the charging wire is not dirty, a voltage of 7 to 8 kV is applied from the power source 11 to the charging device 2, but when the charging wire becomes dirty, the applied voltage gradually increases according to the dirt, and the charging wire When the influence of dirt becomes visible on the image, the voltage will be 0.5 to 1kV higher than normal.
Experiments have shown that the degree of increase is 61LW.

Therefore, if the threshold value of the detection circuit 12a is set to about 500 V, when the charging wire gradually becomes dirty to the extent that it affects the image, the detection circuit 12a will detect the increase in the applied voltage at that time, and A detection signal 13 from the circuit 12a causes a warning display indicating that the charging wire is dirty.

Further, the operation of the recording apparatus is stopped by the detection signal 13, and the wire cleaning device 15 is operated by the control circuit 14 to automatically clean the charging wire.

Therefore, the charging wire is cleaned as appropriate in response to dirt.

<Example> In the above-mentioned example, the case of a constant current power supply was explained, but in the case of a constant voltage power supply, the threshold value of the detection circuit 12b is set to the same value.
By setting the voltage to about 500V, the same operation as in the above embodiment can be achieved. Note that in this case, the detection circuit 12a shown in the drawing is unnecessary.

Moreover, the wire cleaning device 1 in the above-mentioned embodiment
5 may be one in which a cleaner is attached to one end of a wire and the cleaner is moved back and forth by a motor, or one in which the wire is vibrated to shake off dirt.

Furthermore, if the wire cleaning device 15 is not provided, when the recording device is stopped by the detection signal 13, the charging device may be pulled out and the wire may be cleaned with a cleaning pen or the like.

In the above-mentioned embodiment, the case of the primary charging device 2 has been described, but it is also possible to apply the present invention to a charging device such as the transfer charger 8 or the pre-discharge charger section.

<Effects of the Invention> As described above, the present invention is configured to detect contamination of the discharge member by detecting changes in the voltage or current applied to the charging device. dirt can be detected accurately. Therefore, when cleaning the discharge member, it is possible to eliminate excessive leaning or insufficient cleaning, prolonging the life of the charging device, and stabilizing the image of the recording device using this mechanism. be.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. l is a drum, 2 is a charging device, 3 is an optical system, 4 is a developing machine,
5 and 8 are chargers, 11 is a power source, 12a and 12b are detection circuits, 13 is a detection signal, 14 is a control circuit, and 15 is a wire cleaning device.

Claims (1)

[Claims] A detection means for detecting a change in the voltage or current applied to the discharge member of the charging device by comparing it with a predetermined threshold value, and a warning means for receiving a signal from the detection means and displaying a warning about dirt on the discharge member. A dirt detection mechanism for a charging device characterized by the provision of a dirt detection mechanism.