JPH0822202A - Recording device and recording method - Google Patents

Abstract

PURPOSE:To provide a recording device and a recording method capable of obtaining an image of high quality without causing uneven transfer at the time of transferring a toner image from a latent image carrying medium to an intermediate transfer medium. CONSTITUTION:The recording device and the recording method are prepared for transferring, fixing and recording the toner image formed on the latent image carrying medium to a recording medium. The recording device 1 is provided with the intermediate transfer medium 31 having an elastic layer on its surface and a means 34 for pressing the intermediate transfer medium 31 against the latent image carrying medium 11, and the pressing force of the means 34 is set so that the straightness in a width direction of the surface of the elastic layer may be equal to or below the height of the toner image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus and a recording method for recording a toner image developed on a latent image bearing medium on a recording medium via an intermediate transfer medium.

[0002]

2. Description of the Related Art Some recording apparatuses, for example, electrophotographic printers, use an intermediate transfer drum (intermediate transfer medium) for the purpose of color printing. Since the intermediate transfer drum is generally a metal drum having a conductive rubber layer formed on the surface thereof, the surface is not flat and has fine irregularities of about several tens of μm.

Generally, the intermediate transfer drum is pressed against the photosensitive drum (latent image bearing medium), and the developed toner image is transferred onto the photosensitive drum, so that the intermediate transfer drum is in line contact with the photosensitive drum in the width direction. There is a need. However, when the surface of the rubber layer of the intermediate transfer drum has fine irregularities, there is a portion where the photosensitive drum and the intermediate transfer drum do not come into contact with each other, and the contact in the width direction partially becomes point contact. When such point contact occurs, transfer unevenness occurs in which the toner image is not transferred from the photosensitive drum to the intermediate transfer drum at the non-contact portion where the photosensitive drum and the intermediate transfer drum are not in contact with each other. There is a problem that the image quality is significantly deteriorated.

At this time, if the intermediate transfer drum is pressed against the photosensitive drum with a large pressing force, such point contact can be avoided by elastic deformation of the rubber layer. However, if the pressing force is excessively large, the photosensitive layer made of an organic photoelectric material (OPC) formed on the surface of the photosensitive drum is deteriorated or the toner image transferred to the intermediate transfer drum is crushed. Development occurs, which causes problems such as deterioration of the quality of the obtained image.

The present invention has been made in view of the above points, and it is possible to obtain a high-quality image without causing uneven transfer when a toner image is transferred from a latent image bearing medium to an intermediate transfer medium. An object of the present invention is to provide a recording device and a recording method.

[0006]

In order to achieve the above object, according to a recording apparatus of the present invention, an apparatus for transferring and fixing a toner image on a latent image bearing medium to a recording medium and recording the image, An intermediate transfer medium having an elastic layer and a means for pressing the intermediate transfer medium against the latent image bearing medium are provided, and the pressing force of the pressing means is the linearity in the width direction of the elastic layer surface of the toner image. It was set so that it would be less than the height.

On the other hand, according to the recording method of the present invention for achieving the above object, the toner image on the latent image bearing medium is transferred to an intermediate transfer medium having an elastic layer on its surface, and then transferred and fixed to the recording medium. During the recording, the intermediate transfer medium is pressed against the latent image bearing medium so that the linearity in the width direction of the elastic layer surface is equal to or lower than the height of the toner image.

[0008]

When the pressing force of the pressing means for pressing the intermediate transfer medium against the latent image carrying medium is set so that the linearity in the width direction of the elastic layer surface is equal to or less than the height of the toner image,
Even if the intermediate transfer medium and the latent image carrying medium are partially in point contact, the toner image is not transferred to the intermediate transfer medium during the transfer from the latent image carrying medium to the intermediate transfer medium, and uneven transfer does not occur. .

In the present specification, the straightness in the width direction of the elastic layer surface means the distance between the highest portion and the lowest portion of the unevenness in the width direction of the elastic layer formed on the surface of the intermediate transfer medium. Say.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. First, the overall configuration of the electrophotographic printer according to the present invention will be described with reference to FIG. 1. The electrophotographic printer 1 includes a photosensitive unit 10, a developing unit 20, an intermediate transfer unit 30, a cleaning unit 40, a transfer unit 50, and an auxiliary squeeze. It is provided with a roller 60, a sheet feeding device 70, and an exposure system (not shown) that emits exposure light from the direction of arrow A, and each arrow shown in the drawing indicates the rotation or movement direction of each member.

The photosensitive means 10 has a photosensitive drum 11, a static eliminator 12 for removing residual charges on the photosensitive drum 11, and a charger 13 for uniformly charging the photosensitive drum 11.
Prior to removing the residual charges, the surface is cleaned by the cleaning means 40. These cleaning means 40,
The static eliminator 12 and the charger 13 are arranged in this order between the intermediate transfer unit 30 and the developing unit 20 along the rotation direction of the photosensitive drum 11.

The photosensitive drum 11 has a cylindrical drum surface on which a photosensitive layer made of an organic photoelectric material (OPC) is formed. As the material of the photosensitive layer, selenium (Se) based, amorphous silicon (α-Si), or the like can be used in addition to OPC. The static eliminator 12 is an LED array or a small incandescent lamp, and irradiates the surface of the photoconductor 11 with light to erase the residual latent image. The charger 13 uniformly charges the photosensitive drum 11 with the ions generated by the corona discharge.

Here, the exposure system forms an electrostatic latent image on the surface of the photosensitive drum 11, has a laser light source, a liquid crystal shutter, etc., and is based on print information corresponding to each hue of a color original. The photosensitive drum 11 is irradiated with laser light in the direction of arrow A to form an electrostatic latent image corresponding to print information on the surface. Also, print information is transferred to the photosensitive drum 11.
An LED array may be used as the exposing means for irradiating the upper part.

The developing means 20 includes the first developing units 21 to 21.
Driving means 25 for horizontally moving the fourth developing unit 24 and the developing units 21 to 24 in the horizontal direction in the drawing.
Further, a toner cartridge 26 which is arranged in each of the developing units 21 to 24 and is detachably attached to the housing 210 is provided. The drive means 25 has a ball screw 25a and a drive motor 25b. The first developing unit 21 has a liquid tank 211 of liquid toner formed in an upper portion of a housing 210, and a toner cartridge 26 containing liquid toner of each hue in a lower portion thereof. The liquid tank 211 includes a developing roller 212. And squeeze roller 213 are arranged in parallel at a predetermined interval.

The developing means 20 includes each developing unit 21.
To 24 are provided with toner cartridges 26 containing liquid toners of yellow (Y), magenta (M), cyan (C) and black (Bk), respectively. It is located to the right of 11. At the time of development, the driving unit 25 sequentially moves the developing unit 21, the developing unit 22, the developing unit 23, and the developing unit 24 to the photosensitive unit 10 side in this order, and each static image formed corresponding to each hue. The latent images are sequentially developed. As the liquid toner, a liquid carrier in which toner particles such as yellow, magenta, and cyan are dispersed is used.

Here, the details of each developing unit will be described later, but since each developing unit has the same structure, the other developing units are given the same reference numerals as the corresponding portions in the drawing. Description is omitted. The intermediate transfer unit 30 includes an intermediate transfer drum 31 and a charger 32 arranged along the rotation direction of the intermediate transfer drum 31, and the toner images sequentially developed by the developing unit 20 are transferred onto the intermediate transfer drum 31. Are sequentially transferred in layers.

The intermediate transfer drum 31 is formed by forming a thin elastic layer made of, for example, silicone resin, silicone rubber, fluororubber, NBR or the like on the surface of a cylindrical metal drum, and is pressed against the photosensitive drum 11 and developed. Each time the toner image of each hue is developed by the means 20, the toner images are sequentially transferred in layers. The intermediate transfer drum 31 may have an appropriate diameter according to the size of the recording medium.
In this embodiment, the diameter is the same as that of the photosensitive drum 11, but in the case of a large recording medium, the diameter is larger than that of the photosensitive drum 11.

The charger 32 is the charger 13 of the photosensitive means 10.
The intermediate transfer drum 31 is charged by the same principle as described above, and the influence of the previous toner image is canceled at the same time as the effect of the previous toner image is canceled so that the next toner image having a different hue transferred from the photosensitive drum 11 is easily transferred. The toner image transferred onto 31 is prevented from returning onto the photosensitive drum 11.

Here, the intermediate transfer drum 31 is rotatably supported at the substantially center of a support plate 33 whose upper end is rotatably attached to a housing (not shown) via a support shaft 33a, and one end thereof is Due to the spring force of the tension spring 34, the other end of which is locked to the lower end of the support plate 33 in the housing,
The photosensitive drum 11 is pressed with a predetermined pressing force. Then, the intermediary transfer drum 31 is operated to separate from and contact with the photosensitive drum 11 by rotating the attachment / detachment lever 35, the tip of which is locked to the locking pin 33b provided on the lower portion of the support plate 33.

Here, the pressing force of the tension spring 34 is, as shown in FIG. 2 (a), the distance between the highest portion and the lowest portion of the unevenness in the width direction of the surface of the elastic layer 31a of the intermediate transfer drum 31. The linearity R shown is set to be equal to or lower than the height of the toner image developed on the photosensitive drum 11. However, this pressing force is applied to the elastic layer 3 as shown in FIG.
Ideally, it is difficult to realize that 1a elastically deforms and comes into close contact with the entire surface of the photosensitive drum 11, and since it cannot be unconditionally determined depending on the material of the elastic layer 31a to be used, the above setting is made.

Then, in the intermediate transfer means 30, the toner images developed on the photosensitive drum 11 are sequentially transferred onto the intermediate transfer drum 31 while being charged by the charger 32. At the time of this transfer, a small amount of toner image or liquid toner not transferred to the intermediate transfer drum 31 remains on the photosensitive drum 11, but these are cleaned by the cleaning means 40.

A non-woven fabric and a cleaning blade are provided in the cartridge of the cleaning means 40. When the cleaning means 40 is mounted on the electrophotographic printer 1, the cleaning blade comes into contact with the photosensitive drum 11. This cleaning means 40
After the transfer to the intermediate transfer drum 31, the photosensitive drum 11
The residual toner image and the liquid toner residue are scraped by the cleaning blade and wiped with the non-woven fabric for cleaning. The details of the configuration of the cleaning unit 40 will be described later.

The transfer means 50 has a heating roll 51 containing a heater (not shown) and a pressing mechanism (not shown). The heating roll 51 is pressed against the intermediate transfer drum 31 by the pressing mechanism. The color toner images laminated and transferred onto the intermediate transfer drum 31 are heated and pressed to be fixed on the recording paper P. Here, the pressing mechanism separates the heating roll 51 from the intermediate transfer drum 31 when the toner image is transferred from the photosensitive drum 11 to the intermediate transfer drum 31. Then, the heating mechanism presses the heating roller 51 against the intermediate transfer drum 31 with a predetermined pressing force by the time the final toner image transferred portion of the four types of toner images arrives. As a result, the heating roll 51 pressurizes and heats the color toner images laminated and transferred onto the intermediate transfer drum 31 to transfer and fix the color toner images onto the recording paper P supplied from the paper feeding device 70.

The auxiliary squeeze roller 60 is used for the developing means 20.
Is disposed between the intermediate transfer unit 30 and the intermediate transfer unit 30, and removes excess liquid toner, particularly liquid carrier, from the photosensitive drum 11 on which the toner image has been developed. The same effect can be obtained by using a squeeze corona using a charger instead of the auxiliary squeeze roller 60. The paper feeding device 70 is the intermediate transfer drum 3
The recording paper P is supplied between the intermediate transfer drum 31 and the heating roll 50 when fixing the toner image formed on the sheet 1.

The electrophotographic printer 1 of the present invention is constructed as described above and forms a color image as follows.
First, the photosensitive drum 1 cleaned by the cleaning means 40.
The residual charge is removed from the surface of 1 by the static eliminator 12, and the charger 1
It is uniformly charged at 3. Next, laser light is irradiated as shown by an arrow A in FIG. 1 to sequentially form electrostatic latent images corresponding to print information on the surface of the photosensitive drum 11. The electrostatic latent image by the irradiation of the laser light is formed four times in total corresponding to the hues of yellow, magenta, cyan and black.

Next, the ball screw 25a is attached to the drive motor 2
5b, the developing means 20 disposed on the right side of the photosensitive drum 11 in the drawing is horizontally moved to the photosensitive drum 11 side, and the yellow toner image is transferred from the first developing unit 21 to the second developing unit 22. The magenta toner image and the cyan and black toner images are successively developed in the same manner. In this way, the toner images developed by the developing units are sequentially transferred to the intermediate transfer drum 31, and toner images of four colors are stacked and formed on the intermediate transfer drum 31.

At this time, in the intermediate transfer drum 31, the pressing force applied to the photosensitive drum 11 by the tension spring 34 causes the elastic layer 3 to move.
The linearity R in the width direction of the surface 1a is determined by the photosensitive drum 11
The height is set to be equal to or lower than the height of the toner image developed above. Therefore, the toner image of each hue does not cause uneven transfer when being transferred from the photosensitive drum 11 to the intermediate transfer drum 31.

In parallel with the transfer of the toner image developed by the fourth developing unit 24 to the intermediate transfer drum 31,
The pressing mechanism causes the heating roll 51 to move to the intermediate transfer drum 3
Pressed to 1. As a result, the toner images of four colors that have been layer-transferred onto the intermediate transfer drum 31 are heated and pressed to be collectively transferred and fixed onto the recording paper P, and one step of recording a color image is completed.

When the recording of the four color toner images on the recording paper P is completed, the pressure contact of the heating roll 51 with the intermediate transfer drum 31 by the pressing mechanism is released and the developing means 20 is also released.
Is moved to an initial position on the right side of the photosensitive drum 11 by the driving means 25.

[0030]

As is apparent from the above description, according to the recording apparatus and the recording method of the present invention, the pressing force of the pressing means for pressing the intermediate transfer medium against the latent image carrying medium is controlled by the width of the elastic layer surface. Since the linearity in the direction is set to be equal to or lower than the height of the toner image, even if the intermediate transfer medium and the latent image carrying medium are partially in point contact with each other, the latent image carrying medium transfers to the intermediate transfer medium. It is possible to obtain a high-quality image without causing uneven transfer when the toner image is transferred.

[Brief description of drawings]

FIG. 1 is a front view of an electrophotographic printer for explaining an embodiment of a recording apparatus and a recording method of the present invention.

FIG. 2 is a side view illustrating linearity in a width direction of a surface of an elastic layer formed on an intermediate transfer drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic printer 10 Photosensitive means 11 Photosensitive drum (latent image carrying medium) 12 Static eliminator 13 Charger 20 Developing means 21-24 Developing unit 25 Driving means 26 Toner cartridge 30 Intermediate transfer means 31 Intermediate transfer drum (intermediate transfer medium) 31a Elastic layer 32 Charging device 33 Support plate 34 Tension spring (pressing means) 35 Attaching / detaching lever 40 Cleaning means 50 Transfer means 51 Heating roll 60 Auxiliary squeeze roller 70 Paper feeding device

Claims (2)

[Claims] 1. An apparatus for transferring and fixing a toner image on a latent image bearing medium onto a recording medium for recording, comprising: an intermediate transfer medium having an elastic layer on the surface; and the intermediate transfer medium comprising the latent image bearing medium. The recording apparatus is characterized in that the pressing force of the pressing means is set so that the linearity in the width direction of the elastic layer surface is equal to or less than the height of the toner image. 2. When the toner image on the latent image bearing medium is transferred to an intermediate transfer medium having an elastic layer on its surface and then transferred and fixed to a recording medium for recording, the intermediate transfer medium is changed to the elastic medium. A recording method comprising pressing the latent image bearing medium such that the linearity of the layer surface in the width direction is equal to or less than the height of the toner image.