JP2952052B2 - Color image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing device for forming an electrostatic latent image on a recording medium, and a plurality of different color developing devices for developing the electrostatic latent image on the recording medium written by the writing device. The present invention relates to a color image forming apparatus including a unit, and a transport roller pair disposed downstream of the developing unit in the recording medium feeding direction and configured to reciprocate a recording medium in color.

[0002]

2. Description of the Related Art In a color image forming apparatus of the type described above, a conventional liquid color developing apparatus slides on an electrostatic recording paper (recording medium) on which an electrostatic latent image is recorded by an electrostatic head to form an electrostatic latent image. To develop a plurality (3) provided for each color of yellow (Y), magenta (M), and cyan (C).
) Developing units.

Each of the developing units 1Y, 1M, 1C
Are, for example, as shown in FIG. 3, unit main units 3Y, 3M, 3C arranged in a direction perpendicular to the conveying direction of recording paper (not shown) (the direction of the solid arrow in FIG. 3), and unit main unit 3Y. , 3M, 3C, developer tank 5 arranged below
Y, 5M, and 5C. Unit body 3Y, 3
On the upper surfaces of M and 3C, developing slits 7Y and 7 in the longitudinal direction are provided.
M, 7C are formed, and the developing slits 7Y, 7M, 7
C, one end in the longitudinal direction of the developing solution supply pipe 9Y, 9M, 9
C is connected to the upper end of the developer supply pipes 9Y, 9Y.
The lower ends of M and 9C open into the developing solutions 13Y, 13M and 13C stored in the developing solution tanks 5Y, 5M and 5C.

Further, at the lower part of the other longitudinal ends of the developing slits 7Y, 7M, 7C, there are provided developer collecting pipes 15Y, 15Y.
M, 15C are connected at the upper ends, and the lower ends of the developer recovery pipes 15Y, 15M, 15C are connected to the developer tanks 5Y, 5C.
It is open at the top of M and 5C. Vacuum pumps 17Y, 1 are provided at intermediate portions of the developer recovery pipes Y, 15M, 15C.
7M, 17C, and vacuum pumps 17Y, 17M,
17C is configured to introduce a negative pressure into the developing slits 7Y, 7M, 7C. Also, three developing units 1
Y, 1M, and 1C are disposed below the recording paper transport line, and each of them is independently movable up and down, and is configured to be selectively moved up and down (Japanese Unexamined Patent Publication No. Sho 6).
1-117977).

[0005] The image forming apparatus provided with the developing device sequentially develops each color as follows. First, the recording paper is transported in the direction of the solid line arrow by a transport mechanism (not shown), an electrostatic latent image of a yellow portion is formed by an electrostatic recording head (not shown), and the yellow developing unit 1Y is raised to perform recording. When the recording paper slides on the lower surface of the paper, the negative pressure of the developing slit 7Y causes the recording paper to be attracted to the upper surface of the developing unit 1Y. A yellow developer 13Y is attached to the sucked recording paper. The surplus developer 13Y is configured to be collected in the developer tank 5Y via the developer collection pipe 15Y.

In this state, when the recording paper is conveyed by a predetermined length by the conveyance mechanism and the yellow development of the recording portion on the recording paper is completed, the yellow developing unit 1Y is lowered and the recording paper is moved in the direction of the dashed arrow in FIG. Rewind.

Next, the recording paper is conveyed by a conveying mechanism in the direction of the solid line arrow, an electrostatic latent image of the magenta portion is formed by the recording head, and the magenta developing unit 1M is raised, so that the magenta image is formed in the same manner as the yellow color. Color development is performed. After the magenta color development is completed, the recording paper is rewound in the direction of the dashed arrow again, and the cyan developing unit 1C is raised instead of the magenta developing unit 1M, and the recording paper is transported in the solid line direction by the transport mechanism. To develop cyan. The recording paper on which all the colors have been developed is discharged from the discharge port of the image forming apparatus.

[0008]

However, in such an image forming apparatus provided with such a conventional liquid color developing machine, it is necessary to accurately align the position on a recording paper which reciprocates three or four colors. In order to overlap colors, paper feeding accuracy is an important issue, and the accuracy must be kept within a pitch of one dot in the entire image area, and preferably within a pitch of half a dot.

Further, since an image is formed with ink or a wet toner, it is preferable to completely dry each color to prevent the image from being disturbed or mixed in the course of the recording paper. For this reason, it is conceivable that the recording paper is dried by applying heat, but in this case, the paper is dehumidified and its dimensions shrink, and the amount of shrinkage at this time varies depending on the paper quality, the paper skew direction, and the amount of dewatering. , 1
It can exceed the percentage. Therefore, when the paper is fed between the rollers even if the process proceeds to the next step with incomplete drying, it is necessary to prevent the wet toner from offsetting to the roller surface and disturbing the image.

As a method for achieving the above two problems, that is, a method for achieving high-precision paper feeding and offset prevention, a method of writing a scale on the end of paper and correcting the writing position while reading the scale is a large-area imaging system. Is commonly used. However, the scale written on the output screen of A3 size or less must be cut, which is not preferable for use in a general office.

Further, in order to achieve the above two problems, it is only necessary to provide a paper feed roller that is not controlled and does not offset and does not slip, and a grit roller in which particles having sharp angles are bound to a metal roller surface. It has been proposed to use However, while the grit roller is effective for pen plotters mainly composed of line drawings, offset cannot be prevented in a color printer that outputs a solid image almost over the entire surface, and the paper feed accuracy is sufficient under a pressure that does not cause offset. There was a problem that can not be obtained.

The present invention solves the conventional problems described above,
It is an object of the present invention to provide a color image forming apparatus in which colors can be accurately aligned on a recording medium and the offset can be prevented.

[0013]

The structure of the present invention that achieves the above object is as follows.

(1) A liquid color which includes a writing device for forming an electrostatic latent image on a recording medium and a plurality of developing units, and wet develops the electrostatic latent image of the recording medium written by the writing device in different colors. A developing device, and a color image forming apparatus that is disposed downstream of the liquid color developing device in the recording medium feeding direction and that includes a pair of transport rollers that reciprocates the recording medium in a color superimposing manner. A color image forming apparatus, wherein the outer periphery of a roller that contacts an image surface is covered with grit, and the surface is coated with urethane resin.

(2) A liquid color which includes a writing device for forming an electrostatic latent image on a recording medium and a plurality of developing units, and wet develops the electrostatic latent image of the recording medium written by the writing device in different colors. A developing device, and a color image forming apparatus that is disposed downstream of the liquid color developing device in the recording medium feeding direction and that includes a pair of transport rollers that reciprocates the recording medium in a color superimposing manner. A color image forming apparatus, wherein an outer periphery of a roller in contact with an image surface is covered with grit, and the surface is coated with an oil-based resin.

(3) The color image forming apparatus according to (1) or (2), wherein the conveying roller pair does not release the pressing force of the roller pair while repeating the color superimposing reciprocating motion a required number of times. .

[0017]

According to the above construction, the recording medium carrying the unfixed wet developer can be conveyed by the grit without slipping, and the offset can be prevented by applying the urethane resin or the oil-based resin on the surface, and the color overlay can be prevented. Can be performed with high accuracy.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view showing one embodiment of a color image forming apparatus according to the present invention. In FIG. 1, a sheet-like recording paper (recording medium) 19 is conveyed in the direction of arrow A by a pair of paper feed rollers 20, and the leading end is sandwiched between a pair of rubber rollers 25 and a grit roller 24 so that the recording paper is When conveyed to the grit roller 24, the writing head 21 forms an electrostatic latent image of a yellow portion.
The electrostatic latent image of the yellow portion is developed by ascending the yellow developing unit 1Y and slidingly contacting the lower surface of the recording paper 19 so that the yellow developing solution 13Y adheres to the recording paper 19 and is developed. The same is true. When the yellow development is completed, the yellow developing unit 1Y is lowered and the recording paper 19 is moved by a winding roller (not shown).
Is rewound.

Next, by moving the recording paper 19 back and forth, magenta and cyan are developed in the same manner as for yellow. At the time of forward movement of the color superposition, the paper feed roller pair 20 on the upstream side applies tension to the paper by a spring clutch or the like, and at the time of backward movement, is driven in the reverse direction, but slightly faster than the peripheral speed of the grit roller 24. To return the paper while applying tension to the paper. The difference in peripheral speed between the pair of paper feed rollers 20 and the grit roller 24 can be absorbed by sliding with a spring clutch. Then, the registration mark of each color is performed by detecting the registration mark by the optical fiber 22 at the tip of the image forming position. When the development of cyan is completed, a color image is formed on the recording paper 19, and the unnecessary portion formed at the leading end of the recording paper 19 is cut off and discharged to the outside.

In the color image forming apparatus according to the present invention, when the development of each color is performed, even if the grit roller 24 comes into contact with the wet toner in the reciprocating motion, the grit roller 24 does not offset and enables the paper feed without slippage. It is configured as follows. As shown in FIG. 2, the grit roller 24 applies a binder resin 28 on a stainless steel roll 27, and applies grit 29, for example, having an average particle size of 0.03 to
A 0.05 mm carbon-based glass is buried, and the surface thereof is coated with a urethane resin 30.

The grit roller 24 having the above configuration is driven by a spring 26 at a pressure of about 0.5 kg / cm using the rubber roller 25 having a rubber hardness of 70 degrees. With a feed length of 500 mm, a dot feed direction error of 100 μm or less could be achieved. The position accuracy in the width direction is 30μ.
Met.

At this time, the grit roller 24 is entirely coated with the urethane resin 30 in the initial state, but the tip of the grit 29 is worn out and exposed during use, but remains between the grit 29. The coat layer lightly contacted the toner and was slightly stained with the toner, but did not return to the paper surface again.

Further, with a grit roller in which the binder resin 28 is exposed without the urethane resin 30 coating layer, offset cannot be prevented, and under high pressure, the dielectric layer on the recording surface is destroyed and However, in the present invention, the grit roller 24 in which the grit 29 is coated with the urethane resin 30 can appropriately reduce the height of the tip of the grit 29 and break through the dielectric layer. It is considered that the surface of the urethane resin 30 does not prevent the offset. Instead of the urethane resin 27, an oleaginous resin, for example, Florate (trade name: 3M) may be applied, and the grit roller 24 coated with the oleaginous resin also offsets the wet developing toner using Isopar as a carrier solvent. It was effective without birth.

The recording paper 19 of the color image forming apparatus uses roll paper, and is cut by a cutter (not shown) downstream of the rubber roller 25 and the grit roller 24 after image formation. The rubber roller 25 and the grit roller 24 may release the pressing force to correct the initial loading of the roll paper and the tracking deviation (displacement in the width direction) of the paper in use.
The pressure is never released while the reciprocation of the color overlay is repeated the required number of times.

With this configuration, the recording dot position is accurately maintained during the reciprocating movement of color superposition, and a high-quality color image can be obtained.

[0026]

According to the above construction, according to the present invention, the recording medium carrying the unfixed wet type developer can be conveyed by the grit without slipping, and the offset by the urethane resin on the surface can be prevented. Further, the recording dot position can be accurately maintained during the reciprocation of the color superposition, and the color superposition can be performed with high accuracy, so that a high-quality color image can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram of a grit roller.

FIG. 3 is a perspective view of a conventional color developing device.

[Explanation of symbols]

 1Y, 1M, 1C Developing unit 19 Recording paper 21 Write head 24 Grit roller 25 Rubber roller 29 Grit 30 Urethane resin

Continued on the front page (72) Inventor Kiyoshi Oshima 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yoshiumi Tamiya 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh Company (72) Inventor Seiichi Miyagawa 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Inside Ricoh Company (72) Inventor Tadahiro Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Company, Ltd. (56) References JP-A-61-179477 (JP, A) JP-A-60-258050 (JP, A) JP-A-61-50174 (JP, A) JP-A-62-136276 (JP, A) JP-A-3-27807 (JP, A) JP-A-56-48466 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/01 113 G03G 15/10

Claims (3)

(57) [Claims] 1. A liquid color developing device comprising: a writing device for forming an electrostatic latent image on a recording medium; and a plurality of developing units, wherein the electrostatic latent image on the recording medium written by the writing device is wet-developed in different colors. An image forming apparatus, and a conveying roller pair disposed on the downstream side of the liquid color developing device in the recording medium feeding direction and configured to reciprocate the recording medium in a color superimposing manner. A color image forming apparatus, wherein the outer periphery of a roller in contact with a surface is covered with grit, and the surface is coated with urethane resin. 2. A liquid color developing device comprising: a writing device for forming an electrostatic latent image on a recording medium; and a plurality of developing units, wherein the electrostatic latent image on the recording medium written by the writing device is wet-developed with different colors. An image forming apparatus, and a conveying roller pair disposed on the downstream side of the liquid color developing device in the recording medium feeding direction and configured to reciprocate the recording medium in a color superimposing manner. A color image forming apparatus, wherein an outer periphery of a roller in contact with a surface is covered with grit, and the surface is coated with an oil-based resin. 3. The color image forming apparatus according to claim 1, wherein the transport roller pair does not release the pressing force of the roller pair while repeating the color reciprocating reciprocation a required number of times.