KR100438692B1 - An electrophotographic printing machine - Google Patents

Abstract

PURPOSE: An electrophotograph-type printer is provided to prevent a recording paper from separating and swinging and to secure high definition printing by keeping constantly the electrostatic force of the recording paper for a transfer film. CONSTITUTION: An electrophotograph-type printer is composed of a photo sensitive drum(102) printed with a toner on an outer peripheral surface; a transfer drum(104) rotated closely to the photo sensitive drum and coated with a transfer film(104a) on the outer peripheral surface; an absorption roller(106) electrifying the recording paper to be absorbed to the transfer film; an antistatic roller(109) electric-discharging the transfer film; a transfer voltage applying unit having one end coupled to a ground unit and the other end coupled with the transfer drum to apply transfer voltage; an absorption electric charge voltage applying unit having one end connected to the transfer drum and the other end coupled with the absorption roller to apply absorptive electric charge voltage; and an antistatic voltage applying unit having one end coupled with the transfer drum and the other end coupled with the antistatic roller to apply antistatic voltage. The absorption roller is closely contacted to the transfer drum in electrifying the recording paper and separated from the transfer drum in completing the electrification. The antistatic roller is contacted to the transfer drum in electric-discharging the transfer film and separated from the transfer drum in completing the electric discharge. An elastic electro-conductive layer(104b) with elasticity to flexibly contact with the photo sensitive drum is installed at a lower layer of the transfer film.

Description

Electrophotographic printing machine

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printing press, and more particularly, to an electrophotographic printing press such that an electrostatic force between a recording sheet and a transfer drum is kept constant during transfer.

Generally, four-color toners of cyan, magenta, yellow, and black are developed on the photosensitive drum in order for color printing, and each time the developing toner on the photosensitive drum is transferred to the transfer drum again, the four toners on the recording paper are transferred. Polymerization transfer.

1 is a schematic configuration diagram of a conventional electrophotographic printing press, and FIG. 2 is a view showing a state in which power is connected to a plurality of corotrons in the electrophotographic printing press illustrated in FIG. 2.

Referring to FIG. 1, the electrophotographic printer includes a photosensitive drum 2 exposed by light 1 emitted from an optical system for exposure not shown, a developing roller 3 for developing the exposed photosensitive drum 2, And a transfer drum 4 for transferring the recording paper 20 to the photosensitive drum 2. The transfer drum 4 is wound around a transfer film 4a made of a dielectric material on its outer circumferential surface. One side of the photosensitive drum 2 is provided with a charging roller 12 which rotates in contact with it, and transfers the charge of the recording paper 20 to the transfer voltage V2 by applying corona charge to the inside of the transfer drum 4. The corotron 5 is provided. In addition, a gripper 11 for guiding the recording paper 20 to be fed to guide the transfer drum 4 is provided. In addition, an adsorption corrotron 6 for charging the recording paper 20 to the adsorption electrification voltage V1 so as to be adsorbed by the transfer drum 4 is provided between the photosensitive drum 2 and the gripper 11. After the transfer is completed, the separation corrotron 7 for separating the recording paper 20 to a separate charging voltage in order to separate the recording paper 20 from the transfer drum 4, and the separation nose 8 for separating the charged recording paper 20. ) Is installed close to one side of the transfer drum 4, and the antistatic corotron 9 and the like are provided to remove the potential remaining on the transfer drum 4 by applying a static voltage for new printing.

The operation of the electrophotographic printing machine having such a structure will be described. By contact charging with the charging roller 12, the surface of the photosensitive drum 2 is uniformly charged with a constant electrostatic potential. As the photosensitive drum 2 rotates in a counterclockwise direction, the photosensitive drum is exposed by the light 1 so that the exposed portion is charged with the exposure potential so that an electrostatic latent image (not shown) is formed on the photosensitive drum 2. . Then, when the photosensitive drum 2 continues to rotate in the counterclockwise direction and the electrostatic latent image reaches the developing position, due to the potential difference between the electrostatic latent image of the photosensitive drum 2 and the developing roller 3, The toner is transferred to the surface of the photosensitive drum 2 to develop. In this way, the toner developed on the photosensitive drum 2 continues to rotate and reaches the transfer drum 4.

On the other hand, the recording paper 20 to be fed is transferred onto the transfer drum 4 by a device such as a gripper 12 that holds the tip thereof, and is charged to the adsorption charging voltage V1 by the adsorption corotron 6. Then, it is adsorbed by the transfer film 4a. As the transfer drum 4 rotates, the recording paper 20 is moved to a transfer position in contact with the photosensitive drum 4, charged with the transfer voltage V2 by the transfer corotron 13, and the photosensitive drum 2. The toner coated on the sheet is transferred to the recording sheet 20. The recording paper 20 on the transfer drum 4 is rotated together during four rotations on the transfer drum 4 so that four transfer processes are performed on the recording paper 20 over four colors. After the transfer is completed, the transfer film 4a is charged to the antistatic voltage V3 by the separation corotron 7 to charge the charge, and the electrostatic adhesion between the recording paper 20 and the transfer drum 4 is reduced. Then, in the state where the electrostatic adhesion force is reduced, the recording paper 20 is separated from the transfer drum 4 by the separating nose 8, and the printing is completed through the remaining fixing process. When the printing is completed, the transfer film 4a is charged by the alternating current static elimination voltage (FIG. 2) of the antistatic corrotron 9 located inside and outside the transfer drum and is initialized to be electrically neutral.

By the way, since the recording paper 20 has a predetermined length, when the tip area 20a of the recording paper 20 passes through the photosensitive drum 2, the remaining area 20b passes through the adsorption corotron 6. do. When the recording paper 20 charged with the adsorption charge voltage V1 is transferred and passes through the photosensitive drum 2, the voltage of the tip region 20a of the recording paper decreases by the transfer voltage V2. That is, the voltage difference between the leading region 20a of the recording paper 20 transferred through the photosensitive drum 2 and the transfer film 4a becomes V1-V2, and the recording paper which has not yet passed through the photosensitive drum 2 ( The voltage difference between the remaining area 20b and the transfer film 4a of 20 is V1. Therefore, the front end region 20a of the recording paper 20 passing through the photosensitive drum 2 has a small voltage difference with the transfer film 4a, and thus weakens electrostatic force, causing separation or transfer in the transfer film 4a. To interfere with precise printing.

In addition, when the transfer corotron 5 and the antistatic corotron 9 are installed in the transfer drum 6, the surface state of the transfer film of the transfer drum is caused by the corona discharge generated in the plurality of corotrons. Because it is deformed, you need to change it frequently to maintain the transfer performance.

On the other hand, when the above-described corrotron (5, 6, 9) for recording paper charging and transfer film static elimination, there is a lot of ozone harmful to the human body.

The present invention has been made to solve the above problems, and the voltage difference between the transfer film and the recording paper region which has passed through the photosensitive drum and the recording paper region which has not yet passed through the transfer film and the photosensitive drum is made constant. It is an object of the present invention to provide an electrophotographic printing press which can prevent recording paper from being separated or shaken from the transfer drum, and has a structure that can use the transfer film for a long time and can reduce ozone generation.

1 is a schematic configuration diagram of a conventional electrophotographic printing machine.

FIG. 2 is a view illustrating a state in which a power source is connected to a plurality of corotrons in the electrophotographic printer shown in FIG. 2.

3 is a schematic configuration diagram of an electrophotographic printing press according to the present invention.

4 is a view illustrating a state in which a power source is connected to a transfer drum and a plurality of rollers in the electrophotographic printer shown in FIG. 3;

5 is a power circuit diagram connected between a transfer drum and a plurality of rollers in the electrophotographic printer shown in FIG. 4;

<Description of the symbols for the main parts of the drawings>

101 ... light 102 ... photosensitive drum

103 ... developing roller 104 ... transfer drum

104a ... transfer film 104b ... elastic conductive layer

104c ... inner core 106 ... adsorption roller

108 ... Separation nose 109 ... Antistatic roller

111 ... gripper 112 ... anti-roller

120 ... recording paper 204 ... transfer voltage application means

206 ... means for applying electrification voltage 209 ... means for applying static charge voltage

In order to achieve the above object, the electrophotographic printing machine according to the present invention,

A photosensitive drum 102 on which toner is developed on an outer circumferential surface thereof; A transfer drum 104 rotated in close contact with the photosensitive drum 102 and coated with a transfer film 104a on an outer circumferential surface thereof; An adsorption roller 106 for charging the recording paper to be adsorbed on the transfer film 104a; An antistatic roller 109 for static eliminating the transfer film 104a; Transfer voltage applying means (204) connected at one end to the ground terminal and connected at the other end to the transfer drum (104) to apply a transfer voltage; Adsorption charge voltage application means (206) connected at one end to the transfer drum (104) and at the other end connected to the adsorption roller (106) to apply an adsorption charge voltage; One end thereof is connected to the transfer drum 104 and the other end thereof is connected to the antistatic roller 109 to provide an antistatic voltage applying means 209;

The suction roller 106 is in close contact with the transfer drum 104 when the recording paper 120 is charged, and is separated from the transfer drum 104 when the charging is completed;

The antistatic roller (109) is in close contact with the transfer drum (104) when the transfer film (104a) is charged, and is separated from the transfer drum (104) when static elimination is completed;

And an elastic conductive layer 104b having an elasticity so as to be in flexible contact with the photosensitive drum 102 in the lower layer of the transfer film 104a.

Hereinafter, an electrophotographic printing press according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic configuration diagram of an electrophotographic printing press according to the present invention, and FIG. 4 is a view showing a state in which a power supply is connected to a transfer drum and a plurality of rollers in the electrophotographic printing press shown in FIG. 5 is a power circuit diagram connected between the transfer drum and the plurality of rollers in the electrophotographic printer shown in FIG. 4.

Referring to the drawings, the electrophotographic printer includes a photosensitive drum 102 exposed by light 101 emitted from an optical system for exposure not shown, a developing roller 103 for developing the exposed photosensitive drum 102, and a recording sheet. And a transfer drum 104 for transferring the 120 to the photosensitive drum 102. In addition, one side of the photosensitive drum 102 includes a charging roller 112 that contacts and rotates to charge the photosensitive drum 102 so that the toner of the developing roller 103 is transferred.

According to a feature of the present invention, the transfer drum 104 includes an inner core 104c made of a conductive material such as a metal, an elastic conductive layer 104b formed on the next layer of the inner core 104c, and an elastic conductive material. It consists of the transfer film 104a which forms the next layer of the layer 104b. Here, the elastic conductive layer 104b is provided to be in close contact with the photosensitive drum 102 flexibly. At this time, one end of the transfer drum 104 is connected to the ground terminal and is connected to a transfer voltage applying means 204 for applying a transfer voltage.

In addition, between the photosensitive drum 102 and the gripper 111 for guiding the recording paper 120 to be fed to the transfer drum 104, the photosensitive drum 102 is detachably installed and the recording paper 120 is detachably installed. An adsorption roller 106 for charging with an adsorption electrification voltage V1 is provided so as to be adsorbed by the transfer drum 114. At this time, one end of the adsorption roller 106 is connected to the transfer drum 104 and is connected to the adsorption charge voltage applying means 206 for applying the adsorption charge voltage V2. Here, the adsorption roller 106 is driven by separation means such as a cam (not shown) to be separated from the photosensitive drum 102 after the recording paper charging ends.

On the other hand, it is detachable from the photosensitive drum 102 and installed in the position closest to the adsorption roller 106, after the near transfer is completed, in order to remove the residual static charge remaining in the transfer film (104a) ( And a static elimination roller 109 for applying static charge to V3). At this time, one end of the antistatic roller 109 is connected to the transfer drum and is connected to the antistatic voltage applying means 209 for applying the antistatic voltage V3. Here, the antistatic roller 109 is driven by separation means such as a cam (not shown) to be separated from the transfer drum 104 when the static elimination is completed.

After the transfer is completed, the transfer drum 104 transfers the separation corrotron 107 for applying a separate charging voltage and the static discharged recording paper 120 to separate the recording paper 120 from the transfer drum 104. The separator is provided with a separating nose 108.

The operation of the electrophotographic printing machine having such a structure is as follows.

By contact charging with the charging roller 112, the surface of the photosensitive drum 102 is uniformly charged at a constant electrostatic potential. As the photosensitive drum 102 rotates in a counterclockwise direction, the photosensitive drum 102 is exposed by the light 101 so that the exposed portion has a charged potential dropping to an exposure potential and thus an electrostatic latent image (not shown) on the photosensitive drum 102. Is formed. Then, when the photosensitive drum 102 continues to rotate in the counterclockwise direction and the electrostatic latent image reaches the developing position, the potential difference between the electrostatic latent image of the photosensitive drum 102 and the developing roller 103 is increased. The toner is moved to the surface of the photosensitive drum 102 to develop. Thus, the toner developed on the photosensitive drum 102 continues to reach the transfer drum 104. At this time, since the elastic conductive layer 104b is provided inside the transfer drum 104, the recording paper P is adhered to the photosensitive drum 102 flexibly so that the transfer efficiency is high.

On the other hand, the sheet of paper to be fed is conveyed onto the transfer drum 104 by a device such as a gripper 111 that holds the tip of the recording paper 120. The transferred recording paper 120 is charged by the adsorption roller 106 to the adsorption electrification voltage V1 and adsorbed to the transfer film 104a of the transfer drum 104 by electrostatic force. As the transfer drum 104 rotates, the recording paper 120 is transferred to the transfer position in contact with the photosensitive drum 102.

Since the recording paper 120 to be transferred to the transfer position has a predetermined length, when the leading area 120a of the recording paper 120 passes through the photosensitive drum 102, the remaining area 120b moves the adsorption roller 106. To pass. When the transfer voltage V2 is applied when the recording paper 120 charged with the adsorption charge voltage V1 passes through the photosensitive drum 102, the leading region 120a of the recording paper on which transfer is completed is equal to the transfer voltage V2. The drop in the electrostatic force is weakened, there is a possibility of separation or swing in the transfer drum (104). This is applied to the adsorption roller voltage (V1) + transfer voltage (V2) to the adsorption roller 106 at the time when the transfer voltage (V2) is applied, the transfer voltage between the post-transfer recording paper 120 and the transfer drum 104 ( The voltage drop as much as V2) can be prevented, so that the electrostatic force can be kept constant and the separation or fluctuation of the recording paper can be prevented. And. After the paper charging, the adsorption roller 106 is separated from the transfer drum 104 by a driving means (not shown). This is to prevent the toner from burying in the adsorption roller 106 when the recording paper 120 is rotated four times together with the transfer drum 104 so as to form a color image on the recording paper. to be.

Meanwhile, the transfer film 104a needs to be statically initialized for the next transfer. To this end, the transfer film 104a that is contacted by the antistatic roller 109 must be statically charged. In the above transfer process, the transfer film 104a has a region charged with the adsorption charge voltage (V1) and a region charged with the adsorption charge voltage (V1) + transfer voltage (V2). . When the adsorption charge voltage V1 is applied to the adsorption roller 106 in accordance with a feature of the present invention, the antistatic roller 109 applies the antistatic voltage V3 to charge the adsorption charge voltage V1 and the adsorption charge When voltage V1 + transfer voltage V2 is applied, antistatic roller 109 applies the static voltage V3 + transfer voltage V2 to charge. When the static elimination is completed, the antistatic roller 109 is separated from the transfer drum 104 by a driving means (not shown).

The recording paper 20 on the transfer drum 104 is rotated together during the four rotations on the transfer drum 104 such that four transfer processes are performed on the recording paper 120 over four colors. After the transfer is completed, the charge of the recording paper 120 is removed by the separating corotron 107 to reduce the electrostatic adhesion between the recording paper 120 and the transfer film 104a. Then, in the state in which the electrostatic adhesion force is reduced, the recording paper 120 is separated by the separating nose 108 to complete printing.

As described above, the electrophotographic printing press according to the present invention, the adsorption roller at the time when the transfer voltage is applied in order to make the electrostatic force on the transfer film constant between the recording paper region where the transfer is made and the recording paper region which is not yet transferred. The voltage applied by the adsorption charge voltage and the transfer voltage was applied to the transfer film, and the antistatic roller applied the combined voltage to the transfer film. Therefore, the electrostatic force of the recording paper on the transfer film is made constant, preventing separation and fluctuation of the recording paper, thereby enabling high quality printing.

In addition, since the transfer corrotron and antistatic corrotron for corona discharge are not used, the surface state of the transfer film due to corona discharge can be prevented from being deformed, so that it can be used for a long time and can prevent ozone generation that is harmful to the human body. It works.

Claims (1)

A photosensitive drum 102 on which toner is developed on an outer circumferential surface thereof; A transfer drum 104 rotated in close contact with the photosensitive drum 102 and coated with a transfer film 104a on an outer circumferential surface thereof; An adsorption roller 106 for charging the recording paper to be adsorbed on the transfer film 104a; An antistatic roller 109 for static eliminating the transfer film 104a; Transfer voltage applying means (204) connected at one end to the ground terminal and connected at the other end to the transfer drum (104) to apply a transfer voltage; Adsorption charge voltage application means (206) connected at one end to the transfer drum (104) and at the other end connected to the adsorption roller (106) to apply an adsorption charge voltage; One end thereof is connected to the transfer drum 104 and the other end thereof is connected to the antistatic roller 109 to provide an antistatic voltage applying means 209; The suction roller 106 is in close contact with the transfer drum 104 when the recording paper 120 is charged, and is separated from the transfer drum 104 when the charging is completed; The antistatic roller (109) is in close contact with the transfer drum (104) when the transfer film (104a) is charged, and is separated from the transfer drum (104) when static elimination is completed; And an elastic conductive layer (104b) having elasticity so as to be in flexible contact with the photosensitive drum (102) under the transfer film (104a).