JPS6291976A - corona discharger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a corona discharger used in an image forming apparatus such as an electrophotographic copying machine or a printer, and particularly relates to a corona discharger equipped with a means for automatically cleaning a corona discharge electrode. This article relates to a corona discharger.

(Prior Art) In general, photocopying machines and the like use corona to charge a photoreceptor in a negative manner, or to electrostatically transfer a toner image developed on the photoreceptor to a transfer material. A discharger is used. This corona discharger is constructed by arranging a corona discharge electrode made of wire inside a long shield with a U-shaped cross section.A high voltage is applied to the corona discharge electrode to generate a corona. It charges the photoreceptor etc.

By the way, contaminants such as toner and dust are constantly floating in an electrophotographic copying machine, and as copying continues for a long time, these contaminants tend to adhere to the shield electrode of the corona discharge device, the corona discharge electrode, etc. . As described above, contaminants accumulate on each part of the corona discharger as the number of copies increases, and after approximately several thousand copies have been made, charging efficiency begins to decrease and charging unevenness occurs due to the above-mentioned contaminants. . This tendency is particularly noticeable in the case of high speed electrophotographic copying machines and printers, and this ultimately results in a reduction in the quality of the copied images.

In order to solve these problems, conventionally, copying machine users or service personnel have to periodically remove the discharger from inside the machine and clean it, or clean it by putting a cleaning tool in and out of the discharger inside the machine. Primitive methods such as However, discharge electrodes are generally made of thin conductive wires such as tungsten wires, which are often broken by the slightest force. Also, it is difficult to prevent deterioration of image quality unless you remember to clean these regularly.By the way, if the discharger is dirty, it is necessary to take it out and clean it by relying on visual judgment. It becomes very complicated. Y! In some cases, after discovering that the copy quality is low, you should notice that the discharge device is contaminated and clean it! It was difficult to keep the discharger in a satisfactory condition all the time.

Therefore, in order to eliminate these problems, a means has been devised to automatically clean the discharge electrode without removing the discharger from the main body of the copying machine, and this method is disclosed in U.S. Pat.
No. 42,273, U.S. Patent No. 3,870,833, U.S. Patent No. 3,985,400, JP-A-54-2863
It is disclosed in Publication No. 3, etc.

Among these, Japanese Patent Application Laid-Open No. 54-28633.

Several disclosures have been made regarding the timing of automatic cleaning. This mouth! ! The timing for performing I + mistress is as shown below.

(a) Count the number of copies and perform automatic cleaning every predetermined number of copies.

(b) Automatic cleaning is performed at IIν when the power of the copying machine is turned on.

(C) Automatic cleaning is performed every time the copy button is pressed or every time i-P is finished.

(Problems to be solved by IJJ) However, such conventional technology has the following problems.

(a) When performing self-blade cleaning every predetermined number of copies, when multiple copies are being made.

When the predetermined number of copies is reached, the discharge electrode is automatically cleaned, so copying is interrupted during that time and the device cannot be used.Also, the cleaning time can be shortened by increasing the moving speed of the cleaning member. If this happens, you will not be able to obtain the desired cleaning effect.

(b) When automatic cleaning is performed when the copying machine is turned on, the automatic cleaning is performed even when the power is turned 0N10FF due to jam removal, etc., so the user has to wait longer than necessary.

(c) If automatic cleaning is performed every time the copy button is pressed or every time copying is completed, the number of times cleaning will be large, and if automatic cleaning is performed at the start of copying, the time required for copying will be longer.

The present invention has been made to solve the problems of the prior art described above, and its purpose is as follows.

To provide a corona discharger capable of automatically cleaning a discharge electrode without interrupting copying or making copying or waiting time longer than necessary.

(Means for Solving the Problems) In order to achieve the object set forth in item L, the present invention provides a corona discharger equipped with a means for automatically cleaning a corona discharge electrode. The cleaning device is configured to operate the seven cleaning stages only when a time T1 from when the power is turned on to the forming device until it becomes operational and an operating time T2 of the cleaning means satisfy T1≧T2. .

(Example) The present invention will be explained below based on the illustrated embodiments.

FIG. 1 is a perspective view showing an embodiment of a corona discharger according to the present invention.

The L corona discharge $1 includes a long shield plate 2 having a U-shaped cross section, and an opening 3 is provided on the L side of the shield plate 2 along the long f direction. . A front block 4 and a rear block 5 are fitted to both ends of the shield plate 2, and a corona wire 6 as a corona discharge electrode is stretched between these blocks 4 and 5. One end of the corona wire 6 is connected to a high voltage connector 7 fixed to the rear block 5! It is continued. Further, a lead screw 10 is installed between the front block 4 and the rear end of the L section of the shield plate 2 via bearings 8 and 9, and a thread groove 11 of the lead screw 10 is provided with a lead screw 10 for rotating the lead screw 10. By doing so, the holder part 13 of the wire cleaner 12
are fitted so that they can move forward and backward. Note holder part 1
A cleaner arm 14, 15 is extended from the lower end of the cleaner arm 3, and a cleaner pad 16, 17 is fixed to the cleaner arm 14, 15 with a corona wire 6 sandwiched therebetween. Furthermore, holder arms 18 are provided on both sides of the holder portion 13 to prevent the wire cleaner 12 from tilting.
is installed protrudingly. One end of the lead screw 10 is directly connected to a motor 19 fixed to the front block 4L.

FIG. 2 is a block diagram showing the control system of the corona discharger. In FIG. A temperature sensor 21 is a switch sensor that detects when the power switch of the main body of the copying machine is turned on from OFF, 22 is a drive circuit that drives the motor 19, and 23 is an input of output signals from the temperature sensor 20 and the switch sensor 21. This is a control device that drives the motor 19 via the drive circuit 22.

In the configuration described below, in the corona discharge device according to this embodiment, automatic cleaning of the discharge electrode is performed in the following manner. Note that the wire cleaner 12 is normally located at a position where it abuts against the rear edge 24 of the shield plate 2 (outside the charging area) and does not have any influence on one image.

Now, when the power switch of the main body of the copying apparatus is turned on, the switch sensor 21 is turned on. In response to this signal, the control unit 2123 clears its internal memory M+, and then reads the temperature of the fixing roller at that time into the memory M1. Next, the contents of the memory Mo, which holds temperature data in advance, and the memory MI are compared. be done. Here, the temperature data held in the memory Mo will be explained.

The main body of the copying apparatus is provided with a fixing device, and the fixing device usually uses a fixing roller heated by a heater, and is maintained at about 200° C. Of course, when you turn on the power switch of the device in the morning, the fixing roller is cold, so it takes hours T1 for the device to reach 200°C, which is ready for operation.This time varies depending on the model, but for example For a machine with a copy speed of about 40 sheets/minute, it is generally accepted that the initial temperature is 25°C and it takes about 350 seconds (at a rate of 2 seconds/1"0). The time T2 required for cleaning, that is, to move back and forth within the discharger at a speed that provides a good cleaning effect.
In other words, in order to complete the cleaning operation before the fixing roller heats up (becomes ready for copying), it takes at least the time it would take for the fixing roller to heat up. The operation must be started 20 seconds in advance, which means the temperature of the fixing roller is 190°C. Therefore, this value (190 in this case) is held in the memory MQ. That is, in this case, since it is T2, the cleaning operation can be started 330 seconds after the power switch is turned on.

Therefore, the control device 23 compares Mo and Ml, and Ml
>Mo, no cleaning operation is performed; conversely, if M1
In the case of ≦MO, the control device 23 turns on the motor 19 via the drive circuit 22 so that it rotates in the CW force direction when viewed from the output shaft (rotates in the direction of arrow B in FIG. 1).
At this time, the wire cleaner 12 is moved forward (arrow A in FIG.
direction). The elapsed time since the motor 19 was turned ON is counted and stored in the memory M^ in the control device 23.
, and is successively compared with the contents of memory M[, which holds time data in advance.

Here, the time data held in the memory M[ is the time +α required for the wire cleaner 12 to move one way, and is set to 10 seconds here. As a result, variations in the rotational speed of each motor 19 can be absorbed by 0M^≧M
+, the control device 23 sets the motor 19 to 0FFL (at this time, the wire cleaner 12 is in contact with the front edge 25 of the shield plate 2), and then the memory M^
is cleared, and this time the motor 19 is turned on to rotate in the CCW direction. Thereafter, in the same manner, when M^≧M[ is satisfied, the motor 19 is turned off to end the cleaning.

At the same time as or after the end of this cleaning, the ankle roller heats up and becomes ready for copying, so that automatic cleaning of the corona discharger can be performed without any loss of time.

FIG. 3 is a flowchart showing the above operation.

In the embodiment described in E, the cleaning operation Al1 is performed at the same time as the copying machine is activated, but the cleaning operation may of course be completed first.

(Effects of the Invention) The present invention has the above configuration and operation, and the time TI required for a device using this corona discharger to become operational after the power is turned on, and the time T required for automatic cleaning.
Since the discharger is automatically cleaned only when T1≧T2, it is possible to take the necessary time for cleaning without making the user wait.
2, there is no need for cleaning and downtime is short. Therefore, conventional high-speed electrophotographic copying machines or high-speed printers using corona centering devices have a lot of deposits on the discharge electrodes, resulting in poor image quality. In order to prevent this, the discharge electrodes needed to be blue-green frequently, so maintenance services were also difficult.
By applying the present invention, discharge electrodes can be cleaned automatically without wasting time, and maintenance services can be made as simple as possible.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a corona discharger according to the present invention, FIG. 2 is a block diagram showing a control system of the device shown in FIG. 1, and FIG. 3 is a flow chart showing the operation of the control system. be. Explanation of symbols

Claims (1)

[Claims] In a corona discharger equipped with means for automatically cleaning a corona discharge electrode, time T from when an image forming apparatus equipped with the corona discharger is turned on until it becomes operational.
_1 and the operating time T_2 of the cleaning means are T_1≧
A corona discharger characterized in that the cleaning means is activated only when T_2.