JPH0434481A - Image forming device - Google Patents

Abstract

PURPOSE:To facilitate the rapid destaticization of the transfer material charge after transfer by providing a 2nd electrode which impresses the voltage of the same polarity as the polarity of the charge to be imparted to the transfer material between the 1st electrode and a transfer means. CONSTITUTION:The 2nd electrode 502 which impresses the voltage of the same polarity as the polarity of the charge to be imparted to the transfer material P is provided between the 1st electrode 501 and the transfer means 300. The current flowing into the electrode 502 is maintained at the specified voltage as the electrode 502 receives the corona ions of the same polarity as the polarity of the transfer material P from the transfer means 300. On the other hand, electric fields are concd. to the front end of the electrode 501 and gases are ionized by these electric fields, by which the ions necessary for destaticizing the transfer material P are formed in the electrified transfer material P and the electrode 502. The current of the same polarity as the polarity of the transfer corona is passed from the electrode 502 to the electrode 501 and the electrifying charge of the transfer material P flows similarly to the electrode 501. The transfer material P is destaticized in this way and is easily peeled (separated) from an image carrier 202.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus used in an electrophotographic apparatus, a laser printer, etc. The present invention relates to an image forming apparatus that allows peeling.

(Prior Art) This type of image forming apparatus generally develops an electrostatic latent image formed on an image carrier with toner to form a visible image, and then corona charges this visible image from the back side of the transfer material. There has been proposed a system in which image formation is performed by performing transfer using a transfer material, and fixing the transferred visible image on a transfer material. This corona discharge method has been widely used since it has a simple structure and good transfer efficiency.

In addition, in image forming apparatuses that use a reversal development method, such as laser beam printers, a corona charge with a polarity opposite to that of the electrostatic latent image on the image carrier is applied from the back of the transfer material, so electrostatic force is generated in this process. Since electrostatic adsorption force occurs between the surface of the image carrier and the transfer material, the transfer material may not be separated from the image carrier.

For this reason, several peeling means have been proposed and put into practice.

For example, a paper separation device has been proposed that mechanically grasps the leading edge of a transfer material and forcibly separates it from an image carrier.

In addition, air may be blown between the image carrier and the transfer material,
Alternatively, a paper peeling device has also been proposed that attempts to peel the transfer material by sucking air from the back side of the transfer material.

Furthermore, a paper peeling device using a claw separating means or a tape peeling means made of reinforced tape such as Mylar has also been proposed.

In addition, there are also devices in which the transfer material is separated from adsorption to the image carrier after transfer by applying a corona discharge charge of opposite polarity or photostatic discharge using a static elimination lamp to erase the electrostatic charge on the image carrier. Proposed.

Among the above-mentioned separation devices, recently, in those with an image bearing drum diameter of 60φ or more, static electricity is removed from the transfer material by applying an alternating current corona discharge (alternating electric field) after transfer. is proposed.

(Problem to be Solved by the Invention) However, the above-mentioned paper peeling device that mechanically grasps the leading edge of the transfer material and forcibly peels it from the image carrier,
The visible image on the transfer material is erased due to the large size of the device, high manufacturing cost, or because the tip of the transfer material is grabbed.
This is not desirable as there is a problem with the image quality of the image being distorted.

In addition, air may be blown between the image carrier and the transfer material,
Alternatively, a paper peeling device that tries to remove the transfer material by sucking air from the back side of the transfer material is unstable because the toner that forms the visible image on the transfer material immediately after transfer is unfixed. Therefore, the toner scatters due to the airflow, contaminating the inside of the image forming apparatus.

Furthermore, in order to generate such an air flow, there are problems of an increase in the size of the device and a high manufacturing cost, which are undesirable, as mentioned above.

Furthermore, paper peeling devices that use claw separating means or tape separating means reinforced with tape such as Mylar tend to damage the photoconductive voltage on the surface of the image carrier due to factors such as the position and accuracy of the separating claws and tape reinforcement, making them unreliable. I don't like it because it lacks sex.

In addition, photostatic charge removal using a corona discharge charge of opposite polarity or a charge removal lamp is applied to erase the electrostatic charge on the image carrier, thereby separating the transfer material from adhering to the image carrier after transfer. However, there were problems such as disturbing the visible image on the image carrier and having little effect on peeling.

On the other hand, for image carriers with a drum diameter of 60φ or more,
Drums with a diameter of 60φ or less are relatively easy to peel off due to the large curvature of the drum diameter and the stiffness of the transfer material, and also because the device is smaller and the area occupied by the peeling device is narrow, and for reasons such as cost. Since a corona discharge device cannot be used, a high voltage with the opposite polarity to the electrostatic charge of the transfer material is applied to the pointed electrode or conductive fiber electrode after transfer, which is necessary to eliminate the charge from the transfer material. There has been provided an apparatus that eliminates static electricity by generating it and supplying it to a transfer material. Although this device almost satisfies the same conditions as the above-mentioned image bearing member with a drum diameter of 60φ or more, sufficient consideration must be given to insulation because it is located close to the corona discharge section of the transfer device. However, since it requires a high-voltage power supply, there is a problem in that the cost increases.

Therefore, this invention eliminates the need for a dedicated high-voltage power supply and eliminates the need for sufficient insulation treatment.
It is an object of the present invention to provide an image forming apparatus that can reduce costs and quickly eliminate charges on a transfer material after transfer without disturbing a visible image.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an image carrier that carries a visible image, and 20. Transfers the visible image on the image carrier to a transfer material. a transfer means, and a first electrode which is provided downstream in the moving direction of the transfer material with respect to the transfer means and to which a voltage of a polarity different from the charge applied to the transfer material by the transfer means is applied or is grounded.
and a second electrode provided between the first electrode and the transfer means and to which a voltage of the same polarity as the charge applied to the transfer material by the transfer means is applied. That is.

(Function) In the present invention, the second electrode receives corona ions of the same polarity as the transfer material from the transfer means, and the current flowing into the second electrode is maintained at a constant voltage. On the other hand, by concentrating an electric field on the charged transfer material and the second electrode at the tip of the first electrode, the gas is ionized by the electric field,
Ions necessary to neutralize the transfer material are generated. At this time, a current having the same polarity as the transfer corona flows from the second electrode to the first electrode portion, and the electric charges on the transfer material also flow into the first electrode. That is, according to the present invention, the direction in which the electric field acts is controlled by the second electrode so that the charge on the transfer material is quickly removed immediately after the transfer process is completed, so that the charge removal efficiency is high. Static electricity can be removed stably. Therefore, according to the present invention, the transfer material can be easily peeled off (separated) from the image carrier due to the drum curvature of the image carrier and the transfer material's curvature by removing the charge.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is an external perspective view of a laser printer as an image forming apparatus of the present invention.

In FIG. 4, the upper surface of the laser printer main body 10 as an image forming apparatus is lowered one step, and a recess 12 is formed as a first paper discharge section. A recess 13 serving as a second paper ejection section is provided on the left side of the apparatus main body 10, and a paper ejection toilet 14 is detachably attached to the apparatus main body 10 in the recess 13. An operation panel 16 is arranged on the right side of the front face of the apparatus main body 10, and paper cassettes 400, 401, which are detachable from the apparatus main body 10, are attached to the lower part of the operation panel 16. Further, between the paper cassettes 400 and 401, there are openings 24a and 24b for inserting a font car F for adding functions, a card for application software, etc. (not shown).
Or is provided.

FIG. 5 is a diagram showing the back side of the device main body 10.

In FIG. 5, a power switch 26 and an inlet type connector 27 for supplying power to the device are provided on the back side of the main body 10, and an opening 20 is provided at the bottom thereof.

A shield plate 28 made of metal is provided in the opening 20 so as to cover the opening 20.

Connectors 604a and 604b are attached to the shoulder plate 28 to connect to a host device (not shown) such as an electronic filing device or a word processor. The shield plate 28 also includes additional functional devices of this device,
For example, connectors 605g and 605b for connecting to a large capacity paper feeder, sealed paper feeder, etc. (not shown)
, 605C is also installed.

FIG. 6 is a plan view showing the operation panel.

In FIG. 6, the operation panel 16 includes a liquid crystal display 16a that displays the number of sheets, mode, guidance messages, etc., an LED display 16b that lights up LEDs to indicate various states, and switches 16c that instruct various operations. It is made up of.

The LED display 16b indicates "Online" which indicates whether or not it is connected to an external device (online/offline), "Ready" which indicates that the main body 10 is ready for operation, and "Ready" which indicates that the device main body 10 is in an operational state, and which indicates that the image is being transferred. It consists of the following indicators: ``Data'' to indicate, ``Operator'' to request an operator call, ``Service'' to request a service call, and ``Mode'' to indicate auto/manual.

The switch 16c is constituted by, for example, a menu key, a value key, a numeric keypad (not shown), or the like. The above menu key is composed of two keys, next item key and previous item key, and a plurality of menu information displayed on the left half of the liquid crystal display 16a is incremented each time the next item key is pressed, and each time the previous item key is pressed. are decremented and displayed, and these display operations are repeated cyclically. The value key is also composed of two keys: next item and previous item, and a plurality of value information corresponding to the menu information displayed on the left half of the liquid crystal display 16a is incremented each time the next item key is pressed. Each time the previous item key is pressed, each item is decremented and displayed, and these display operations are repeated cyclically. The operator selects and instructs a desired operation by operating the menu keys and value keys.

FIG. 1 is a schematic longitudinal sectional view mainly showing the inside of this device body.

In FIG. 1, a manual feed guide 32 that can rotate in the direction of the arrow in the figure around a fulcrum 30 is attached to the right side of the device main body 10.
A side cover 34 is attached to the lower part of the apparatus, and is rotatable in the direction of the arrow shown in the figure, about a fulcrum 36 provided at 1 degree of the main body of the apparatus.

Further, a drum-shaped photoreceptor 202 as an image carrier is provided inside the apparatus main body 10.
2, a charging device 204 consisting of a scorotron, a photosensitive section 206 as an electrostatic latent image forming means, a developing bag W2O3 for performing a developing process, a transfer device 300 consisting of a corotron, and a drum cleaner are arranged around the 2 in the direction of rotation shown by the arrow. Device 21
o1 and pre-exposure device 301 are arranged in sequence. Of these, a photoreceptor 202, a charging device 204, a developing device 208, a drum cleaner device 210, and a pre-exposure device 301 are integrated and arranged as an electrophotographic process unit 200 that is removably attached to the apparatus main body 10. There is.

In the laser exposure unit 100, a laser diode (not shown) is provided in a case 104, and a laser beam 102 emitted from the laser diode is condensed by a condenser lens device 118 and sent to a polarizer 108. There is. The polarization device W108 is equipped with a polyhedral mirror 106 that rotates at high speed.
6, the laser beam 102 reflected by the Fe lens 1101
Passing through the reflective mirror 112 and dustproof glass 114, the photoreceptor 2
02 exposure section 206 is scanned.

The developing device 208 includes a magnetic roller 220, scraping rollers 222a and 222b, a two-component developer consisting of carrier and toner, etc. in a case 224.
The electrostatic latent image on the photoreceptor 202 is developed with toner. Further, a toner replenishing device 226 for replenishing consumed toner is attached to the developing device 208.

The drum cleaner device 210 includes an elastic blade 232 in a case 230 that is in contact with the photoreceptor 202, and is configured to scrape off toner remaining on the photoreceptor 202 from the photoreceptor 202. The scraped toner is sent to the toner storage section 214 inside the case by a conveying roller 236.

The fixing device f350 includes a heat roller 352 having a built-in heater lamp 351, and a pressure roller 353 that is in pressure contact with the heat roller 352.
The toner image is melted and fixed on the paper P as the paper P passes between the spaces 353. heat roller 3
52 and the pressure roller 353 are connected to the lower casing 354.
and an upper casing 356, and has a structure that prevents heat from escaping to the outside so as to ensure a favorable temperature atmosphere necessary for fixing. This heat roller 3
52 is in contact with a cleaner 358,
The heat roller 35 is kept in a clean state so that good fixing can be performed at all times, and the heat roller 35 is maintained by the thermistor 360.
The structure is such that the surface temperature of the image forming apparatus 2 is detected and temperature control is performed to maintain the temperature necessary for fixing.

In addition, the heat roller 35 is heated inside the upper casing 356.
A paper peeling guide 368 is disposed near the downstream side of the contact portion 362 between the paper P 2 and the pressure member 353 to ensure that the leading edge of the paper P guided to the fixing device 350 is peeled off from the heat roller 352. . Note that a paper guide 366 is provided on the paper exit side of the fixing device 350 to guide the fixed paper P to the first paper ejection roller pair 408.

An image transfer section 209 formed between the photoreceptor 202 and the transfer device 300 is provided within the apparatus main body 10.
On the upstream side of the image transfer section 209, there are a transfer guide roller 422, a paper guide pair 420, and an aligning roller pair 4.
06 is provided.

On the downstream side of the image transfer section 209, a peeling device 500, a paper conveyance guide 416, a fixing device 350, a first pair of paper discharge rollers 408, and a second pair of paper discharge rollers 409 are arranged. These paper ejection roller pairs are provided with a static elimination brush 4 connected to the non-image forming side of the paper P along the conveyance direction.
12.413 is provided.

At the bottom of the apparatus main body 10, paper feed rollers 402, 403,
Paper cassettes 400.401 are arranged near paper feed rollers 402.403.
A paper empty switch (not shown) for detecting the paper P in 401 is also provided. Further, on the side surface of the case 450.470 of the paper cassette 400.401, there is also a paper size detection switch (not shown) for detecting the paper size of the stored paper P.
An attachment detection switch (not shown) is provided to detect whether the device 401 is attached to the device main body 10.

A gate device 442 is provided on the downstream side of the first pair of paper discharge rollers 408 to change the conveyance path of the paper P to a first paper discharge section or a second paper discharge section, as shown in the figure. Two positions, the solid line side and the dotted line side, can be selected around the fulcrum 444, so that the paper P can be conveyed to the first paper discharge section or the second paper discharge section. ing.

A paper transport path 42 is located on the right side of the paper cassette 400, 401.
4, and this paper transport path 424 includes paper guides 431, 432, 433, paper transport roller pairs 440.
441.

The paper guide 431 is configured integrally with the side cover 34. On the upstream side of the pair of paper conveyance rollers 440, there is a paper guide 435.4 that guides the paper P to the pair of aligning rollers 406.
36 are provided. Further, a paper transport path 425 for manual paper feeding is provided above the paper transport path 424, and this paper transport path 425 merges with the paper transport path 424.

An aligning switch 630 is provided near the aligning roller pair 406, and an aligning switch 630 is provided near the aligning roller pair 406.
A paper discharge switch 414 is provided near 8 to detect paper P moving within the apparatus main body 10.

On the back side of the apparatus main body 10, there is an engine control board (not shown) equipped with an engine control circuit that controls each electrical device installed in the apparatus main body 10 to control operations for completing the electrophotographic process, and a power source. (not shown) etc. are arranged.

A printer control board 602 equipped with a printer control circuit that controls the operation of the engine control circuit is disposed in the board storage section 18 provided between the paper cassettes 400 and 401. Up to two printer control boards 602 can be installed depending on the degree of function addition, for example, adding types of fonts, kanji, etc. Further functions can be added by inserting font cards (not shown) for adding functions into the two font card connectors 610a and 610b.

However, in the image forming apparatus, the drum-shaped photoreceptor 2
02 is rotated, the surface potential of the photoconductor 202 is kept constant by the action of the pre-exposure device 301, and then uniformly charged by the action of the charging device 204, and exposed to the laser beam 102 emitted from the laser exposure unit 100. body 20
2 to form an electrostatic latent image corresponding to the image signal.

This electrostatic latent image on the photoreceptor 202 is developed by a developing device 208 and visualized as a toner image, which is transferred to the image transfer section 202.
Sent to 9th.

On the other hand, the paper P taken out from the paper cassette 400 or 401 in synchronization with this toner image forming operation is sent to a paper guide 432 or 433, passes through a paper conveyance path 424, passes through a pair of aligning rollers 406, and a pair of paper guides. 42
0, the image transfer unit 209 sends the toner image through the transfer roller 422, and the toner image previously formed on the photoreceptor 202 is transferred onto the paper P by the action of the transfer device 300. Next, the paper P is separated from the photoreceptor 202 by a peeling device 500, and is further guided by a transport guide 416 to pass through a paper transport path 410 and sent to a fixing device 350, where the toner image is melted and fixed on the paper P. Ru.

Further, the appearance P fed from the manual feed guide 32 passes through the manual feed paper transport path 425, joins the paper transport path 424, and the same operation as described above is performed.

The appearance P that has passed through the fixing device 350 is transferred to the paper ejection roller pair 408
and sent to the gate device 440.

The position of the gate is selected based on instructions from the host computer. If the first position is selected, the paper P is sent to the first paper output section, and the paper P is sent to the second paper output section. It is discharged onto the top cover via a pair of rollers 409. If the second position is selected, the paper P is sent to the second paper discharge section and is discharged onto the paper discharge tray 14.

Note that after transferring the toner image onto the paper P, the photoreceptor 202
The residual toner remaining on the top is removed by a drum cleaner 234 consisting of an elastic blade 232 into a toner collecting section 2 in the device.
Collected in 36.

Next, the peeling device 500 in this embodiment will be described in detail.

FIG. 2 is a detailed view showing a first embodiment of the peeling device of the present invention.

The transfer device 300 includes a corona wire 300b made of tungsten or the like, a grounded shield case 300a, and a high voltage power source 600. The peeling device 500 is disposed downstream of the transfer device 300 in the moving direction of the paper sheet P as the transfer material, is closely opposed to the photoreceptor 202, and has a pointed ground electrode 501 as a first electrode;
A second electrode is disposed near the pointed ground electrode 501 and upstream in the transfer material moving direction with respect to the pointed ground electrode 501.
, and a Zener diode ZD that applies a voltage of the same polarity as the charge on the paper P to the pointed counter electrode 502 . Here, the tip end of the pointed counter electrode 502 is covered with a first insulating member 505, a part of which faces the corona wire 300b, and is further grounded via a high voltage Zener diode ZD. A pointed ground electrode 501 is disposed downstream of the pointed counter electrode 502 in the paper P movement direction with a second insulating member 504 in between so as to face the image carrier. In the figure, t indicates the toner transferred to the paper P, and C in the figure indicates the charge on the paper P charged by the transfer device 300.

FIG. 3 is a front view showing the structure of the pointed ground electrode 501 and the pointed counter electrode 502.

In FIG. 3, the pointed ground electrode 501 or the pointed counter electrode 502 has a continuous pointed shape and is disposed close to and opposite to the photoreceptor 202.

The operation of such an embodiment will be explained.

During the transfer process and peeling process, the high voltage power supply 600
A voltage of approximately KV is applied to the corona wire 300b, and corona ions are generated due to the relationship between the grounded shield case 300a and the pointed counter electrode 502. This positive charge is discharged to the shield casing 300a and the paper P, forming a backside charge C from the photoreceptor 202 via the transfer material P, and the toner t is moved to the paper P by the electric field formed between the photoreceptor 202 and the paper P. On the other hand, the pointed counter electrode 50 receives a positive charge from the corona wire 300b.
2, a current flows through the high-voltage Zener diode ZD, and the pointed counter electrode 502 is controlled to have a constant positive voltage. Note that in this embodiment, the high voltage Zener diode ZD is selected to have a voltage of approximately IKV. The paper P that has obtained the toner image t and is charged with an electric charge C proceeds to a peeling process, and this paper P
An electric field is concentrated from the pointed counter electrode 502 to the tip of the pointed ground electrode 501, and lines of electric force shown at 602 in the figure are formed. This electric field ionizes the gas, producing ionized ions. The generated negative charge is supplied to the paper P along the lines of electric force indicated by 602 in the figure, and the positively charged charge C of the -edge paper P flows into the pointed ground electrode 501 and is neutralized. Incidentally, the insulating member 504 was provided because the pointed ground electrode 501 and the pointed counter electrode 502 are located close to each other by about 2 mm, but it is not necessarily necessary to provide it as long as there is no leakage. In addition, in the peeling device 500 of the present invention, the electric field is applied until immediately after the transfer process, so that static electricity is removed at a rapid stage, and even if the paper P is separated from the photoreceptor 202 and the back surface charges increase. Since the pointed ground electrode 501 is not in contact with the paper P, a sudden change in the electric field does not occur, and static electricity can be removed without disturbing the toner image t on the paper P.

FIG. 7 shows a second embodiment of the invention.

In FIG. 7, in addition to the pointed ground electrode 501 and pointed counter electrode 502, a pointed counter electrode 503 is further provided.

According to this second embodiment, although the exclusive area is slightly larger, an extremely high static elimination effect is achieved.

FIG. 7 is a block diagram showing a third embodiment of the present invention.

In FIG. 7, a peeling device 500 includes a pointed counter electrode 50
A pointed ground electrode 501 is formed by making the pointed part of No. 2 at a slight angle θ.
This increases the concentration of the electric field by arranging the electric field opposite to the electric field.

Also in this third embodiment, it is possible to install the corona wire 300b to which a high voltage is applied without an insulating member to prevent leakage.

FIG. 9 is a diagram showing another configuration example of the pointed ground electrode and the pointed counter electrode used in this example.

In FIG. 9, the electrodes are constructed from conductive fibers.

Even with such an electrode structure, the static elimination effect is only 3rd.
It is similar to the one shown in the figure.

In this embodiment, the pointed counter electrode is grounded via the high-voltage Zener diode ZD as a voltage applying means, but the same effect can be obtained by using an impedance element such as a resistor element.

[Effects of the Invention] As explained above, according to the present invention, peeling can be performed quickly and efficiently without disturbing the image on the transfer material, and the occupied area is small, the structure is simple, and parts can be removed easily. This has the effect of reducing the number of points.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view of an image forming apparatus to which an embodiment of the present invention is applied, FIG. 2 is a schematic diagram showing a first embodiment of a paper peeling device according to the present invention, and FIG. FIG. 4 is an external perspective view of an image forming apparatus to which the present invention is applied; FIG. 5 is an external view of the back connection portion of the image forming apparatus; FIG. 7 is a schematic diagram showing a second embodiment of the present invention, FIG. 8 is a schematic diagram showing a third embodiment of the present invention, and FIG. 9 is a schematic diagram showing a third embodiment of the present invention. FIG. 1 is an external view showing a conductive fiber electrode used in an example of the present invention. 501... Pointed ground electrode (first electrode), 502...
Pointed counter electrode (second electrode), 503... Second pointed counter electrode, ZD... Zener diode, 504...
First insulating member, 505...Second insulating member, 506
...Third insulating member, 300a... Shield case,
30'Ob... Corona wire 600, high voltage power supply, 202... Image carrier.

Claims (1)

[Scope of Claims] An image carrier carrying a visible image, a transfer means for transferring the visible image on the image bearer to a transfer material, and a transfer means provided downstream in the moving direction of the transfer material with respect to the transfer means, and a first electrode to which a voltage of a polarity different from the electric charge applied to the transfer material by the transfer means is applied or grounded, and the transfer means is provided between the first electrode and the transfer means, and the transfer means An image forming apparatus comprising: a second electrode to which a voltage of the same polarity as the charge applied to the image forming apparatus is applied.