JP2006072334A - Wet image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet image forming apparatus capable of preventing irregularities in a printed image and the soiling of the foundation of recording paper from occurring by restraining the unnecessary transfer of developer to the peripheral surface of a developer supporting body. <P>SOLUTION: The wet image forming apparatus has a photoreceptor drum on which a toner image is formed, a developer supporting roller which supports developer so as to supply toner to the photoreceptor drum, a developer applying roller which applies the developer to the developer supporting roller, and a transfer roller to which a toner image formed on the photoreceptor drum is transferred. The length in the shaft direction of the peripheral surface of the developer applying roller is longer than that of the peripheral surface of the developer supporting roller, and the length in the shaft direction of the peripheral surface of the transfer roller is shorter than that of the peripheral surface of the developer supporting roller. Both ends of the peripheral surface of the developer applying roller are arranged on an outer side in a rotary shaft direction than those of the peripheral surface of the developer supporting roller, and both ends of the peripheral surface of the transfer roller are arranged on an inner side in the rotary shaft direction than those of the peripheral surface of the developer supporting roller. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wet image forming apparatus that forms an image using a developer containing a toner in a carrier liquid.

  As an apparatus that forms an image by transferring toner onto recording paper, powdery toner is carried on the surface of the developing roller, and the powdery toner is applied to the electrostatic latent image formed on the photosensitive drum for development and development. Image forming apparatus for transferring the toner image to a recording paper, and wet image formation in which a developer containing toner in a carrier liquid is carried on the surface of a developing roller, and this developer is applied to a photosensitive drum for development. The device is known. Since the toner used in the latter apparatus is finer than the toner used in the former apparatus, generally, the latter apparatus can form an image with higher image quality than the former apparatus.

  A conventional wet image forming apparatus generally includes, for example, a coating unit including at least one transport roller, a developer support (for example, a developing roller), and an image support (for example, a photosensitive drum). Have. In such a wet image forming apparatus, the developer needs to be applied thinly and uniformly on the developer support by the application means, and further supplied uniformly to the latent image surface on the image support by the developer support. There is.

  However, during the rotation of the transport roller, excess developer may accumulate at both ends of the transport roller and transfer to other members. If excessive developer is deposited on the developer support, for example, the developer will accumulate between the developer support and the image support, and the image may flow when developing the toner into a latent image. There has been a problem that image disturbance occurs and background stains occur.

  Therefore, in the wet image forming apparatus described in Patent Document 1, an excessive developer is used by using a plurality of transport rollers used for the coating unit and shortening the width of the transport roller closer to the developer support (developing belt). Is prevented from falling from both ends of the conveying roller and adhering to the developer support, and as a result, image noise is prevented.

JP-A-8-123205 (see FIGS. 1 and 3)

  However, in the wet image forming apparatus described in Patent Document 1, when the developer is applied from the transport roller to the developer support, the transport roller and the developer support are brought into contact with each other, so that the surplus on the developer support. There is a possibility that a large amount of developer will adhere. That is, since the width of the transport roller that contacts the developer support is set shorter than the width of the developer support, both end portions of the transport roller are brought into contact with the developer support and the transport roller. In other words, the developer accumulated in the liquid crystal is transferred to the peripheral surface of the developer support, and as a result, there is a problem that the printed image is not disturbed and the background of the recording paper cannot be prevented.

  Therefore, in view of the above circumstances, the present invention prevents the occurrence of the disturbance of the printed image and the contamination of the background of the recording paper by suppressing the unnecessary transfer of the developer to the peripheral surface of the developer support. It is an object of the present invention to provide a wet-type image forming apparatus capable of performing

  The wet image forming apparatus according to claim 1, which solves the above problem, includes a photosensitive drum for forming a toner image and a developer that supports a developer for supplying toner to the photosensitive drum. A support roller, a developer application roller that applies developer to the developer support roller, and a transfer roller to which a toner image formed on the photosensitive drum is transferred, the photosensitive drum, and the developer support The rotation axes of the roller, the developer application roller, and the transfer roller are parallel to each other, and the axial length of the peripheral surface of the developer application roller is longer than the axial length of the peripheral surface of the developer support roller. The axial length of the peripheral surface of the transfer roller is shorter than the axial length of the peripheral surface of the developer support roller, and both ends of the peripheral surface of the developer application roller are on the peripheral surface of the developer support roller. Than both ends It disposed rotating shaft outward, that both ends of the transfer roller peripheral surface is arranged in the axial direction inward from both ends of the developer supporting roller peripheral surface, and wherein.

  Therefore, the wet image forming apparatus of the present invention defines the lengths in the axial direction of the developer application roller, the developer support roller, and the transfer roller, thereby preventing the developer from being applied to the peripheral surface of the developer support roller. Necessary transitions can be suppressed, and the printed image can be prevented from being disturbed and the background of the recording paper to be stained.

  The wet image forming apparatus according to claim 2, wherein a photosensitive drum for forming a toner image, a developer supporting roller supporting a developer for supplying toner to the photosensitive drum, and the developer supporting At least two developer application rollers for applying a developer to the roller, and at least two transfer rollers to which a toner image formed on the photosensitive drum is transferred, the photosensitive drum, the developer support roller, The rotation axes of the at least two developer application rollers and the at least two transfer rollers are parallel to each other, and the axial length of the peripheral surface of the at least two developer application rollers is the peripheral surface of the developer support roller. The axial length of the peripheral surface of the transfer roller that is in contact with the photosensitive drum of the at least two transfer rollers is longer than the axial length of the developer solution. The photosensitive drum is shorter than the axial length of the roller peripheral surface, and both end portions of the peripheral surface of each of the at least two developer application rollers are disposed on the outer side in the rotation axis direction than both end portions of the peripheral surface of the developer support roller, Both ends of the peripheral surface of the transfer roller in contact with the drum are arranged on the inner side in the rotation axis direction than both ends of the peripheral surface of the developer supporting roller.

  According to the wet image forming apparatus of the present invention, it is possible to suppress unnecessary transfer of the developer to the peripheral surface of the developer support, and to prevent the printed image from being disturbed and the background of the recording paper from being stained. It becomes.

  A wet printer as a wet image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side sectional view showing a configuration of a wet printer 100 according to the present embodiment. The wet-type printer 100 is an apparatus for forming an image by carrying a developer containing toner in a carrier liquid on the surface of a developing roller. Character / image information input from an external device such as a computer is converted into a laser beam. It is an apparatus that prints and outputs on recording paper P1 by the electrophotographic method used.

  The wet printer 100 roughly includes a control unit 20, a drive unit 30, a laser scanning unit (hereinafter abbreviated as LSU), a developing unit 50, a transfer unit 70, and a fixing unit 80. The control unit 20 manages a print control operation, a transport control operation, and the like. The drive unit 30 drives various mechanisms. The LSU 40 outputs a laser beam modulated according to character / image information. The developing unit 50 develops the latent image corresponding to the character / image information using a developer by electrophotography. The transfer unit 70 transfers the toner image developed by the developing unit 50 onto the recording paper P1 at the transfer position. The fixing unit 80 fixes a transport mechanism that transports the recording paper P1 and the toner image transferred onto the recording paper P1 transported by the transport mechanism.

  The drive unit 30 that is a drive source of various mechanisms of the wet printer 100 includes a plurality of actuators that drive the various mechanisms. These actuators are all connected to the control unit 20 and are driven and controlled by the control unit 20. The drive unit 30 can rotate, for example, the developing roller 55 constituting the developing unit 50, the photosensitive drum 61, the heat roller 81 constituting the fixing unit 80, and the like.

  A paper feed tray 11 on which the recording paper P1 is set and a carry-in port 12 into which the recording paper P1 is introduced are formed on the side surface on one end side of the housing of the wet printer 100, and a recording port is introduced on the side surface on the other end side. A discharge port 15 through which the paper P1 is discharged and a discharge tray 16 are formed. The recording paper P1 conveyed from the carry-in port 12 to the inside of the wet printer 100 is conveyed through the conveyance path 13 and the toner image is transferred to the surface thereof at the transfer position formed by the transfer unit 70, and is conveyed through the conveyance path 14 to the fixing unit. The toner is fixed at a fixing position 80 and discharged from the discharge port 15 to the outside of the wet printer 100.

  The LSU 40 is an example of an exposure unit for forming a latent image on the surface of the photosensitive drum 61. The laser diode 41, the collimator lens 42, the cylindrical lens 43, which is a light source unit, the polygon mirror 44, the imaging lens 45, and the deflection mirror. 46. In addition to the LSU 40, the exposure unit may employ, for example, an LED (Light Emitting Diode) or a reduction optical system.

  The laser diode 41 emits laser light. The laser diode 41 is driven and controlled by the control unit 20, and is turned on / off (that is, modulated) based on inputted character / image information. The laser light emitted from the laser diode 41 is incident on the collimator lens 42, thereby converting the diffused light into a parallel light beam.

  The laser beam converted into the parallel light beam is converged only in the sub-scanning direction in the vicinity of the reflection surface of the polygon mirror 44 by the cylindrical lens 43. The direction in which the laser beam is scanned on the photosensitive drum 61 is a main scanning direction (the axial direction on the photosensitive drum 61). The sub-scanning direction is a direction perpendicular to the main scanning direction and indicated by a tangent line of the photosensitive drum 61 at a position where the laser beam on the circumferential surface of the photosensitive drum 61 is irradiated. The beam is converged in the sub-scanning direction in the vicinity of the reflecting surface of the polygon mirror 44, and the vicinity of the reflecting surface of the polygon mirror 44 and the exposed position of the photosensitive drum 61 are substantially conjugate with respect to the imaging lens 45 in the sub-scanning direction. By setting the position to a proper position, the beam can always be converged to the same position in the sub-scanning direction without being affected by the surface tilt error of the reflecting surface of the polygon mirror 44.

  Since the polygon mirror 44 is rotated by a motor (not shown), the laser beam converged linearly (converged only in the sub-scanning direction) at a portion where the polygon mirror 44 is reflected by the cylindrical lens 43 is scanned in the main scanning direction. And is incident on the imaging lens 45. The laser light that has passed through the imaging lens 45 is deflected by the deflection mirror 46 to form a beam spot on the photosensitive drum 61. The beam spot is scanned at a constant speed in the main scanning direction. Since the beam spot moves in the main scanning direction while being modulated, a scanning line corresponding to the character / image information is formed on the photosensitive drum 61. Further, since the photosensitive drum 61 rotates in the sub-scanning direction, scanning lines are sequentially formed on the photosensitive drum 61 in the sub-scanning direction. As a result, a two-dimensional electrostatic latent image based on character / image information is formed on the photosensitive drum 61.

  The developing unit 50 includes a developer tank 51 that stores developer, a pump unit 52 that pumps the developer from the developer tank 51, a metering roller 53 to which the pumped developer is supplied, and a metering roller 53. A measuring blade 54 that measures the supplied developer, a developing roller 55 that carries the measured developer, a charging corona 56 for developing roller that charges the developing roller 55, and scrapes the developer from the surface of the developing roller 55. And a developing roller cleaning blade 58 to be removed. Further, in the vicinity of the developing unit 50, a latent image is formed by the LSU 40 and the latent image is developed by the toner supplied from the developing roller 55, and the toner adheres to the latent image portion on the surface of the photosensitive drum 61. For this purpose, a photosensitive drum charging corona 62 for charging the photosensitive drum 61 is disposed. Further, a photosensitive drum cleaning blade 63 is disposed to scrape off the toner on the surface of the photosensitive drum 61 that has not been transferred to an intermediate transfer roll 71 (described later) of the transfer unit 70.

  The toner image developed on the surface of the photosensitive drum 61 is transferred to the recording paper P1 by the transfer unit 70. The transfer unit 70 includes an intermediate transfer roller 71, a carrier liquid squeeze roller 72, a carrier liquid cleaning blade 73, a secondary transfer roller 74, and an intermediate transfer roller cleaning unit 75.

  A transfer bias having a polarity opposite to that of the toner is applied to the intermediate transfer roller 71, and the toner image on the surface of the photosensitive drum 61 is primarily applied to the surface of the intermediate transfer roller 71 at the rolling contact portion between the photosensitive drum 61 and the intermediate transfer roller 71. Transcribed. The untransferred toner that is not transferred at the rolling contact portion and remains on the surface of the photosensitive drum 61 is removed from the surface by the photosensitive drum cleaning blade 63. The carrier liquid adhering to the surface of the intermediate transfer roller 71 together with the toner image is squeezed from the surface by the carrier liquid squeeze roller 72. The carrier liquid removed from the surface of the carrier liquid squeeze roller 72 by the carrier liquid cleaning blade 73 is collected in the developer tank 51.

  Here, the intermediate transfer roller 71 and the secondary transfer roller 74 are installed at positions facing each other across the conveyance path of the recording paper P1, and are in rolling contact with a predetermined nip pressure. The toner image transferred to the surface of the intermediate transfer roller 71 is transferred to the recording paper P1 that is transported through the transport path by the action of a transfer electric field, nip pressure, etc. The intermediate transfer roller 71 is interposed between the intermediate transfer roller 71 and the secondary transfer roller 74 in order to prevent the nip pressure from being directly applied to the photosensitive drum 61. Further, the toner remaining on the surface of the intermediate transfer roller 71 as untransferred toner after being transferred onto the recording paper P1 is removed by the intermediate transfer roller cleaning unit 75 and then collected in the developer tank 51.

  The recording paper P1 onto which the toner image has been transferred is guided to the fixing unit 80 through the conveyance path 14. The fixing unit 80 fixes the toner image on the recording paper P1 by heating and pressing. The fixing unit 80 includes a heat roller 81 that heats the recording paper P1 and a roller that is installed at a position facing the heat roller 81 across the conveyance path. The fixing unit 80 sandwiches the recording paper P1 between itself and the heat roller 81. And a press roller 82 for pressing. The recording paper P1 on which the toner image is fixed by the fixing unit 80 is discharged from the discharge port 15.

  2 shows the photosensitive drum 61, the cleaning blade 63, the developing roller 55, the cleaning blade 58, the measuring roller 53, the measuring blade 54, and the intermediate transfer roller 71 as viewed from the direction of the arrow A in FIG. It is a figure.

  When the printing operation by the wet printer 100 is executed, the developer is gradually accumulated at both axial end portions 116 of the developing roller 55. Similarly, the developer is also accumulated at both axial ends 118 of the measuring roller 53. In the present embodiment, the axial length of the circumferential surface of the measuring roller 53 is set to be longer than the axial length of the circumferential surface of the developing roller 55. Further, both end portions 118 of the metering roller 53 are arranged so as to be positioned on the outer side in the axial direction from both end portions 116 of the developing roller 55.

  In the wet printer 100 shown in FIG. 2, the developer is supplied from the developer tank 51 (see FIG. 1) to the measuring roller 53, accurately measured by the measuring roller 53, and applied to the developing roller 55. At this time, both end portions 118 of the metering roller 53 are positioned on the outer side in the axial direction from both end portions 116 of the developing roller 55, so that the developer accumulated at both end portions 118 of the measuring roller 53 is transferred to the surface of the developing roller 55. And will not adhere.

  Thereafter, toner is electrophoresed between the developing roller 55 and the photosensitive drum 61 in accordance with the electrostatic latent image on the surface of the photosensitive drum 61, and a toner image is formed on the photosensitive drum 61. At this time, both end portions 116 of the developing roller 55 are positioned on the inner side in the axial direction with respect to both end portions 112 of the photosensitive drum 61, so that the developer stored in the both end portions 116 of the developing roller 55 is stored in the photosensitive drum 61. Although it adheres to the surface, as will be described later, this adhesion does not cause disturbance of the image to be printed and contamination of the background of the recording paper.

  Next, the toner image is transferred onto the recording paper P1 by the transfer unit 70 (see FIG. 1). The axial length of the circumferential surface of the intermediate transfer roller 71 is set to be shorter than the axial length of the circumferential surface of the developing roller 55. Further, the both ends of the intermediate transfer roller 71 are arranged so as to be located on the inner side in the axial direction than the both ends 116 of the developing roller 55. As a result, the developer accumulated at both end portions 116 of the developing roller 55 does not adhere to the surface of the intermediate transfer roller 71 via the photosensitive drum 61, and the printed image is disturbed and the background of the recording paper is not covered. The occurrence of dirt can be prevented.

  As described above, the axial length of the circumferential surface of the measuring roller 53 is set longer than the axial length of the circumferential surface of the developing roller 55, and both end portions 118 of the measuring roller 53 are longer than both end portions 116 of the developing roller 55. It arrange | positions so that it may each be located in an axial direction outer side direction. For this reason, unnecessary transfer of the developer from the both end surfaces 118 of the measuring roller 53 to the peripheral surface of the developing roller 55 is suppressed. Further, the axial length of the peripheral surface of the intermediate transfer roller 71 is set to be shorter than the axial length of the peripheral surface of the developing roller 55, and both end portions of the intermediate transfer roller 71 are connected to both end portions 116 of the developing roller 55. Are also arranged so as to be located on the inner side in the axial direction. As a result, it is possible to provide a wet image forming apparatus that can prevent the printed image from being disturbed and the recording paper from being stained.

  In the embodiment of the present invention, only one measuring roller 53 is provided, but a plurality of measuring rollers may be used. In that case, the axial length of the circumferential surface of each metering roller is set to be longer than the axial length of the circumferential surface of the developing roller 55. Further, both end portions of each metering roller are arranged so as to be positioned on the outer side in the axial direction from both end portions 116 of the developing roller 55. In the embodiment of the present invention, the number of intermediate transfer rollers 71 is one, but a plurality of transfer rollers may be used. In that case, the axial length of the peripheral surface of the transfer roller that contacts the photosensitive drum 61 is set to be shorter than the axial length of the peripheral surface of the developing roller 55. Further, both ends of the transfer roller in contact with the photosensitive drum 61 are disposed so as to be located on the inner side in the axial direction from both ends 116 of the developing roller 55. Also with these configurations, there is provided a wet image forming apparatus capable of suppressing unnecessary transfer of developer to the circumferential surface of the developing roller 55 and preventing the printed image from being disturbed and the background of the recording paper from being stained. Is possible.

It is a sectional side view showing the composition of the wet printer of the embodiment of the present invention. FIG. 2 is a diagram showing an extracted configuration in the vicinity of the developing roller when viewed from the direction of arrow A in FIG.

Explanation of symbols

50 Developing unit 51 Developer tank 52 Pump unit 53 Measuring roller 54 Measuring blade 55 Developing roller 56 Developing roller charging corona 58 Developing roller cleaning blade 61 Photosensitive drum 62 Photosensitive drum charging corona 63 Photosensitive drum cleaning blade 71 Intermediate transfer roller 100 Wet printer 116 Developing roller end 118 Weighing roller end

Claims (2)

A photosensitive drum for forming a toner image;
A developer support roller supporting a developer for supplying toner to the photosensitive drum;
A developer application roller for applying a developer to the developer support roller;
A transfer roller to which a toner image formed on the photosensitive drum is transferred,
The rotational axes of the photosensitive drum, the developer support roller, the developer application roller, and the transfer roller are parallel to each other,
The axial length of the peripheral surface of the developer application roller is longer than the axial length of the peripheral surface of the developer support roller, and the axial length of the peripheral surface of the transfer roller is the peripheral surface of the developer support roller. Shorter than the axial length of
Both ends of the peripheral surface of the developer application roller are disposed on the outer side in the rotation axis direction than both ends of the peripheral surface of the developer support roller, and both ends of the peripheral surface of the transfer roller are both ends of the peripheral surface of the developer support roller Is arranged on the inner side in the rotational axis direction,
Wet image forming apparatus characterized by the above. A photosensitive drum for forming a toner image;
A developer support roller supporting a developer for supplying toner to the photosensitive drum;
At least two developer application rollers for applying developer to the developer support roller;
And at least two transfer rollers to which a toner image formed on the photosensitive drum is transferred,
The rotational axes of the photosensitive drum, the developer support roller, the at least two developer application rollers, and the at least two transfer rollers are parallel to each other,
A transfer roller in which the axial length of the peripheral surface of the at least two developer application rollers is longer than the axial length of the peripheral surface of the developer support roller, and of the at least two transfer rollers, the transfer roller contacts the photosensitive drum The axial length of the peripheral surface is shorter than the axial length of the developer support roller peripheral surface,
Both end portions of the peripheral surface of each of the at least two developer application rollers are arranged on the outer side in the rotation axis direction than both end portions of the peripheral surface of the developer support roller, and both end portions of the transfer roller peripheral surface contacting the photosensitive drum are Being arranged on the inner side in the rotation axis direction from both ends of the peripheral surface of the developer support roller;
Wet image forming apparatus characterized by the above.

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