JPH0437874A - image forming device - 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 Field of Industrial Application The present invention relates to an image forming apparatus such as a copying machine or a printer using electrophotographic technology, and in particular, to an image forming apparatus such as a copying machine or a printer using electrophotographic technology. This invention relates to improvements to automatic cleaning devices.

[Prior Art] In an image forming apparatus using electrophotographic technology, toner, dust, and other contaminants are more or less floating in the apparatus at all times. As copying is continued for a long time, these contaminants and the like adhere to the shield member of the built-in corona charger, the corona wire (charging wire), and the like. As described above, contaminants and the like accumulate on each part of the corona '4Et device as the number of copies progresses, and after approximately several thousand copies have been made, the charge removal efficiency decreases due to the contaminants and the like. Then, static electricity removal becomes uneven. And because of these,
Eventually, the quality of the copied image will deteriorate.

Therefore, users of the copying machine and service personnel regularly check the copying machine from inside the machine. Primitive methods have been used, such as removing electrical appliances and cleaning them, or cleaning the equipment by taking them in and out with cleaning tools. However, the charged wire is generally a conductive thin wire such as a tungsten wire, and it is very often that the charged wire is cut by the slight force. Also, if you do not forget to clean these items regularly, it will be difficult to prevent the image quality from deteriorating. However, if there is dirt inside the charger, it is necessary to remove it and rely on visual judgment to clean it, which is very complicated. In reality, contamination of the charger is often noticed and cleaned after a deterioration in copy image quality is discovered, making it difficult to keep the charger always in a satisfactory condition.

In view of these problems, the corona charger is equipped with a corona wire cleaning member that is movable along the charging wire and a drive mechanism that moves the cleaning member, and the corona charger is equipped with a drive mechanism that moves the cleaning member without removing the corona wire from the main body of the copying machine. It is possible to operate the drive mechanism in a timely manner according to a preset program in the control circuit to automatically clean the charged wire, or to perform the cleaning operation at any time by manually sending an operating signal to the drive mechanism using a manual switch. , for example, U.S. Pat. No. 3,842,273, U.S. Pat. No. 3,870,833, U.S. Pat.
65400, JP-A-62-288865, etc.

First, as a control method for operating the cleaning means, cleaning is performed every time the main unit is powered on.

Second, the cleaning operation is performed when the power is turned on while the roller temperature of the fixing device of the main body device is low. Thirdly, depending on the number of copying operations of the main unit, cleaning is performed, for example, once every several thousand plates. Control methods such as the following have been proposed. Among these, a method that operates the cleaning means when the temperature of the fixing roller is low, that is, uses a wait-up time, is often used.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when the roller temperature drops below a certain temperature (T,), the cleaning means makes one reciprocation. The number of times of cleaning was exactly the same when the temperature was lower than that (T1) and when the temperature was slightly lower than that temperature (T1). However, if the copying machine is left unattended for more than a day or night, such as when the power switch is turned OFF at the end of the day's use and then turned ON again the next day, floating toner or ozone may be generated. Matter slowly builds up and adheres to the shield plate or charged wire over time, and when you turn on the power switch first thing in the morning.
Due to the dew condensation that occurs at the same time, the adhesion becomes extremely strong. At this time, the dirt may not be completely removed by the cleaning means reciprocating only once. In addition, when a paper jam occurs around the drum, an unfixed toner image remains on the transfer paper, so when removing it, the toner scatters and seriously damages the charger's shield member and IT line. It gets dirty. When such a paper jam occurs, it takes a very long time to remove it because the user is concerned about getting his or her hands dirty. Therefore, although the temperature of the fixing device becomes sufficiently low, since the cleaning means only makes one reciprocation, there is a problem that significant dirt on the charging wire and the shield member cannot be sufficiently cleaned.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide an image forming apparatus in which the number of times of cleaning is increased depending on the degree to which the temperature of the fixing device is low, so that sufficient cleaning of the corona f appliance is always performed. It is something to do.

[Means for solving problem n] In order to achieve the above object, the present invention provides a corona charger in which a cleaning means automatically reciprocates along the charger;
In an image forming apparatus that includes a fixing device that heats and fixes paper after transfer, and a temperature detection device that detects the temperature of the fixing device, the number of times that the number of reciprocating movements of the aforesaid agitation device is controlled by the temperature of the fixing device It has a control means.

[Function] According to the present invention, the number of reciprocating movements of the cleaning means is controlled according to the temperature of the fixing device by using the number of times control means, so that when the temperature of the fixing device is sufficiently low, the number of reciprocating movements of the cleaning means is controlled. The corona charger is reciprocated multiple times, and the corona charger is always thoroughly cleaned.

[Embodiment] FIG. 8 is a schematic sectional view of an image forming apparatus to which the present invention is applied.

In FIG. 8, 1 is the main body of the apparatus, 2 is a manuscript table made of a transparent glass plate, etc. fixedly provided on the upper part of the main body 1;
A document 0 is placed at a predetermined position on the document table 2 with the image surface facing downward, and is pressed and fixed by a document pressure bonding plate 3 .

The original 0 is illuminated by a lamp 4, and its optical image is guided to a photosensitive drum 12 by an optical system comprising reflection mirrors 5, 6, 7.8, 9.10 and an imaging lens 11.

The lamp 4 and the reflecting mirrors 5 to 10 move at a predetermined speed in the direction of arrow a to scan the original 0.

The photosensitive drum 12 is driven to rotate at a predetermined circumferential speed in the direction of the arrow in the figure, and after the surface of the photosensitive drum 12 is uniformly charged by the charger 13, the above-mentioned optical system corresponds to the original image. An electrostatic latent image is formed. Next, the electrostatic latent image is developed by a developing device 14, and a developed image (toner image) to be transferred to a transfer paper is formed on the surface of the photosensitive drum 12.

On the other hand, the transfer paper P is stacked and housed in a paper cassette 15 and placed at the bottom of the main body 1 of the apparatus, and is sent out one by one by a pickup roller 16 and transported by a slip roller 17 to the nip of a registration roller 18. Enter the department.

The registration roller 18 starts rotating at a timing such that the developed image on the photosensitive drum 12 and the transfer paper P match, and sends the transfer paper P to the surface of the photosensitive drum 12 via a transfer guide (not shown). The transferred transfer paper P has an image on the surface of the photosensitive drum 12 transferred by the transfer charger 19, and is sent to the constant weight 22 via the conveying section 21. Next, the image on the transfer paper P is heated and fixed as a permanent image by the fixing device 22, and the transfer paper P is transferred to the ejection roller 2.
4 and is discharged onto a tray 25 outside the apparatus.

Note that the toner image is transferred to the transfer paper P, the toner remaining on the photosensitive drum 12 is removed by the cleaner 26, and the above-described image forming process is repeatedly performed.

Next, the automatic charging wire cleaning means provided in the transfer charger 19 will be described in detail.

FIG. 3 is a sectional view of the automatic cleaning means for the transfer charger 19, and FIG. 4 is a sectional view taken along the line AA in FIG. Section 5 is a sectional view of the main part shown in correspondence with FIG. 3, and FIG. 6 is a sectional view taken along line BB in FIG.

In FIGS. 3 to 6, 30 is a charging wire, and 31, mainly seen in FIG. 3, is a holding member (also called a holder) for the cleaning member.
is fixed with adhesive etc. in two places. Here, cleaning member 3
2 is made of an elastic member such as felt or sponge. Further, the holding member 31 is made of flexible resin, and is attached so as to be movable in the longitudinal direction along an opening provided on the U-shaped back surface of the shield member 33. A protrusion 31a is provided at the lower part of the holding member 31. In addition, the holding member 31 has ribs 31b protruding from both sides.
An opening is provided on the U-shaped side surface near the front end of the shield member 33, and when the holding member 31 is positioned at the front end of the shield member 33,
When the rib 31b enters the side opening and is located at a position other than the end, the side surface of the shield member 33 closes the rib 31b.
are pushed inward to each other, and the cleaning member 32 is pressed against the charging wire 30. Then, by moving the holding member 31 in the front-to-back direction, dust and the like attached to the charging wire 30 can be scraped off.

A guide member (also referred to as a shield stand) 34 is fixed to the lower part of the shield member 33 over the entire length thereof, and has a groove shape and an opening in the part that fits into the opening provided on the back surface of the shield member 33. ing. and,
The holding member 31 is held between the groove-shaped portion and the back surface of the shield member 33 so as to be movable in the longitudinal direction.

The guide member 34 has wing-shaped guide portions 34a and 34b on the left and right sides in its cross-sectional shape, and when the transfer charger 19 is attached to the main body, the guide portions 34a and 3
4b is inserted in the front-rear direction along the rail member 35 provided on the main body of the copying machine. The rail member 35 has a U-shape on the left and right, and a push-up spring 3 that presses the transfer charger 19 toward the photosensitive drum 12 is provided inside the U-shape.
6 is fixed.

Further, the rail member 35 is provided with an opening over almost the entire length in the longitudinal direction, and a drive block 37 is provided in this opening so as to be movable in the longitudinal direction.

The drive block 37 has two pairs of guide portions 37a on both sides,
37b, and is held along the opening of the rail member 35 by the guide portions 37a and 3b, making it movable in the longitudinal direction.

A cylindrical hole 38 passing through the drive block 37 in the longitudinal direction is provided in the lower part of the drive block 37, and a fourth hole 38 is provided in the hole 38.
A lead screw 39 shown in the figure passes through it. This lead screw 39 has approximately the same length as the longitudinal dimension of the charger, and is rotatably held on both sides by bearings provided at both ends of the rail member 35 via sliding bearings. There is. Further, a single internally threaded rib is provided in the hole 38 of the drive block 37, and is engaged with the threaded portion of the lead screw 39.

The rotation of the lead screw 39 causes the drive block 37 to move in the longitudinal direction.

Further, as shown in FIG. 4, the drive block 37 has walls vertically provided on the front side and the rear side in the longitudinal direction. Here, the upper surface of the wall 40 on the back side is higher than the upper surface of the wall 41 on the near side, and a step is provided.

A worm wheel 42 is fixed to the rear end of the lead screw 39, and a worm gear 44 that is directly connected to and driven by a DC motor 43 meshes with the worm wheel 42, as shown in the seventh section. The drive block 37 is driven forward or backward by the forward and reverse rotation of the motor 43.

Further, the rail member 35 is fixed to the conveyance section 21 of the apparatus main body 1, and the conveyance section 21 is integrated with the rail member 35 and the transfer charger 19 at a position spaced apart from the photosensitive drum 12 for jam removal and the like. The transport section 2
It is rotatably fixed around the vicinity of the end of the fixing unit 1 as a center of rotation.

In the operating state, in order to maintain the gap between the charging wire 30 and shield member 33 of the transfer IF device 19 and the photosensitive drum 12 at predetermined values, a part of the transfer IF device 19 is connected to the photosensitive tram 12 (not shown). It is positioned by coming into contact with the holding member.

Further, near the front end of the lower surface of the rail member 35, a seventh
As seen in the figure, the microswitch 45 is fixed, and a portion of the drive block 37 is attached to one of the switches 45.
By pressing the collar, a control section (not shown) can detect that the drive block 37 has reached the front end of the rail member 35.

Next, the operation will be explained.

First, when attaching the transfer charger 19 to the apparatus main body 1, the guide portions 34a, 34 of the guide member 34 of the transfer IT device 19 are placed in a state where the conveyance portion 21 is spaced apart from the photosensitive drum 12.
When b is inserted along the inside of the U-shape of the rail member 35, it is pushed upward by the push-up spring 36, and the guide portions 34a and 34b enter along the upper side of the U-shape of the rail member 35. . In other words, this state is the fifth
As shown in the figure.

At this time, the length of the tip of the protrusion provided at the lower part of the holding member 31 is longer than the wall 40 on the back side and longer than the wall 41 on the near side with respect to the two walls provided on the FFI moving block 37. It is determined that it will be higher.

Usually here, shame! Since the block 37 is detected by the microswitch 45 and stopped at the front end of the rail member 35, when the transfer charger 19 moves toward the back side, the holding member 37 is stopped as shown in FIG. 31 protrusion 31
a is positioned and fixed between the two walls of the drive block 37.

Then, when the mounting is completed and the conveying section 21 is further pushed up to a position close to the photosensitive drum 12, the transfer charger 19
comes into contact with the frame of the photosensitive drum 12, and furthermore, the conveying section 21
moves upward, and the transfer charger 19 relatively moves downward within the rail member 35, as shown on the left side of FIG.
The device main body 1 is in an operating state with the tip of the protrusion of the holding member 31 positioned below the front wall 41 of the drive block 37.

In this state, when the main body 1 of the apparatus is energized and the DC motor 43 is rotationally driven by a control section (not shown), the lead screw 39 rotates and the drive block 37 begins to move toward the rear side.

The holding member 31 is then pushed by the wall of the drive block 37 and begins to move together. The drive block 37 is the rail member 35
It stops when it hits the back side. In this state, DC motor 4
3 continues to be energized in the locked state. In other words, the state shown on the right side of the fourth ward is reached. In this way, the main body control section reversely rotates the DC motor 43 after a predetermined period of time has elapsed.

The drive block 37 then begins to move toward the front.

When a part of the drive block 37 pushes the lever of the microswitch 45, the main body control section detects the position of the drive block 37, stops the DC motor 43, and finishes the cleaning work of the charging wire 30.

Further, when the transfer charger 19 is to be taken out from the apparatus, it can be taken out by performing the reverse operation to the above-mentioned mounting. That is, the conveying section 21 is connected to the photosensitive drum 12.
The engagement between the holding member 31 and the drive block 37 is released by pulling out the charger 19 toward the front side while being separated from the holding member 31 .

Next, control of the cleaning means will be explained.

Here, the control method for operating the cleaning means is always performed when the power is turned on. here,
When the power is turned on, one is when the operator turns on the main switch of the main unit to start the main unit, and the other is when the operator turns on the main unit by closing the front cover of the main unit after burying the paper jam. Indicates when the power is turned on (if you open the front cover etc. to clear a paper jam, the interlock switch will turn off and the power will turn off automatically).

Here, the process will be explained using the flowchart shown in FIG. First, when the power is turned on to the main body, it is detected whether the drive block 37 is in a normal position and the microswitch 45 is turned on. When the microswitch 45 is turned on, the DC motor 43 is rotated in the reverse direction and the drive block 3 is turned on.
Bring 7 to its normal position. Next, the temperature of the fixing roller 200 shown in FIG. 9 is detected. In this embodiment, as shown in FIG. 9, this is done by a thermistor 201 in contact with the fixing roller 200. When this temperature is known, the time required until the device main body 1 becomes ready for operation can be determined. However, this time relational expression is determined experimentally in advance. Then, the weight-up time is compared with the time required for one reciprocating movement of the cleaning member 32. Note that the time required for one reciprocating movement of the cleaning member 32 is experimentally determined in consideration of the worst case conditions. Here, if the time required for one reciprocating movement is shorter than the weight-up time, the motor 4
Start the forward rotation of step 3. On the other hand, when the time is long, the motor 4
Rotation operation 3 is not performed. When the motor 43 is rotated in the forward direction, after a predetermined period of time has elapsed after the forward rotation, the motor 43 is rotated in the reverse direction. Note that this predetermined time is also determined experimentally. Then, the drive block 37 turns on the microswitch 45.
When the motor 43 is turned off, the motor 43 is stopped. The temperature of the fixing roller 200 is detected again. The weight-up time is calculated and compared with the time required for one reciprocating movement of the cleaning member 32. Thereafter, the above-mentioned operation is repeated.

According to this method, when the weight-up time is long, the f electric wire 30 can be cleaned multiple times. Therefore, when the fixing roller 200 is sufficiently cool and dirt is firmly attached to the charged wire 30, such as first thing in the morning, or when clearing a jam around the drum, the fixing roller 200 may become extremely dirty, Even if it takes a long time, the cleaning member 32 can be moved back and forth in a scattered manner, so that the dirt can be sufficiently removed.

FIG. 2 shows another example of the present invention. In the example of FIG. 2, the number of reciprocating movements is determined based on the first detected temperature. First, when the main unit is powered on, the drive block 3
7 is in the normal position and the microswitch 45 is turned on. Micro switch 45 is O
When the N state is reached, the motor 43 is reversely rotated to bring the drive block 37 to its normal position. Next, the temperature of the fixing roller 200 is detected. This detection is done by thermistor 201
It is carried out by If the temperature is below 50℃,
The motor 43 starts rotating in the normal direction. After rotating for a predetermined time, it rotates in reverse, and when the microswitch 45 is turned on, it rotates forward again, making a total of three reciprocating movements. Further, when the temperature of the fixing roller 200 exceeds 50° C. and is below 80° C., the fixing roller 200 is controlled to make two reciprocating movements, and when the temperature is below 120° C., it makes one reciprocating movement.

By adopting such a control method, when the fixing roller 200 is sufficiently cool and dirt is firmly attached to the charging wire 30, such as first thing in the morning, or when clearing a jam around the drum, If there is significant dirt and it takes a long time to dispose of it, the cleaning member 32 can move back and forth in a scattered manner, so that the dirt can be sufficiently removed.

Note that the temperature that determines the number of reciprocations is not particularly specified and is determined for each machine.

[Effects of the Invention] As explained above, according to the present invention, the number of reciprocating movements of the cleaning means is controlled in accordance with the temperature of the fixing device by having the number of times control means, so that the number of reciprocating movements of the cleaning means is controlled according to the temperature of the fixing device. When the temperature is low enough, the cleaning means reciprocates multiple times and always cleans the corona fi.
This provides effects such as sufficient cleaning of the T-ware and copying work can be carried out without any problems.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one of the methods for controlling the automatic cleaning means in the image forming apparatus of the present invention in the form of a flowchart;
The figure is an explanatory diagram showing another one as a flowchart,
3 is a sectional view of the automatic cleaning means in the image forming apparatus of the present invention, FIG. 4 is a partially cutaway sectional view taken along the cutting line A-A in FIG. 3, and FIG. 5 is the automatic cleaning means of FIG. 3. 6 is a sectional view taken along cutting line B-B in FIG. 5, FIG. 7 is a perspective view of the automatic cleaning means in FIG. 5, and FIG. 8 is an image in which the present invention is applied. FIG. 9 is a sectional view showing one embodiment of the forming device, and FIG. 9 is an enlarged perspective view showing a part of the fixing device shown in FIG. 1... Device body, 12... Photosensitive tram,
14...Developer, 19...Transfer charger,
22...Fuser, 30...11: Electric wire,
31... Holding member, 32... Cleaning member, 3
3... Shield member, 34... Guide member, 35
...Rail member, 36...Push-up spring, 3
7... Drive block, 39... Lead screw 43... DC motor, 45... Micro switch, 200... Fixing roller, 201... Thermistor, P... Transfer paper. 4 other people

Claims (1)

[Claims] 1. Image formation having a corona charger in which the cleaning means automatically reciprocates along the charger, a fixing device that heats and fixes the paper after transfer, and a temperature detection device that detects the temperature of the fixing device. An image forming apparatus comprising: a number of times control means for controlling the number of reciprocating movements of the cleaning means based on the temperature of the fixing device.