JP2001188398A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic device provided with a simple paper sheet transporting route capable of color printing at high speed on successive paper by the tandem system. SOLUTION: This device performs the high speed printing by a simple paper sheet transporting route by placing a part or whole of plural printing units in the vertical direction, and arranging an intermediate transfer body on one side of the printing units, and moreover arranging the paper sheet transporting route and the fixing device on the other side, and then transferring the toner image on the upper part of the intermediate transfer body and thereafter fixing after reversing the transporting route of the paper sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly, to a color electrophotographic apparatus for forming a color image on continuous paper using an intermediate transfer member.

[0002]

2. Description of the Related Art As a full-color recording method in a conventionally known electrophotography method, one photosensitive member as a recording material is
It is known to rotate and develop one color at each rotation. This method has a disadvantage that the time required for color printing is four times as long as that for single-color printing because the photoconductor rotates four times. Another drawback is that it is difficult to use continuous paper. A so-called tandem method has been known for a long time as a method for improving the disadvantage of this method, in which four photoconductors are linearly arranged, and each photoconductor is developed one color at a time and color-printed at the same speed as that of single-color printing. . This method has the advantages that high-speed printing is possible and that continuous paper can be used, and printers for cut paper and continuous paper have already been commercialized. However, a tandem-type printer for continuous paper using an intermediate transfer member, which has an advantage that it can be stably transferred to various types of paper and has a simple paper transport path and enables stable paper traveling, has not been found at present. US Pat. No. 5,455,668 discloses an example of an apparatus configuration of a printer for one-sided and two-sided printing using an intermediate transfer body in a tandem system for cut paper, but does not show continuous paper.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an electrophotographic apparatus for color printing using a tandem system mainly using four photoconductors, using an intermediate transfer body. An object of the present invention is to propose an apparatus configuration that enables high-speed printing on one side and both sides on continuous paper. Another object of the present invention is to propose a device configuration in which the entire device is small in a tandem system.

[0004]

SUMMARY OF THE INVENTION According to the present invention, in order to achieve the above object, some or all of a plurality of printing units are arranged substantially vertically, and intermediate transfer is performed on one side of the substantially vertically arranged printing units. The body was provided with a paper transport path and a fixing device on the other side. In addition, a two-component developer is used for high-speed development, the developing device can be installed below or on the side of the photoconductor, and unfixed images transferred from an intermediate transfer body to enable printing on continuous paper. Until the toner image is fixed, a non-contact state with a member such as a roller is maintained.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a printing unit used in the electrophotographic apparatus of the present invention. FIG. 2 (a), FIG. 2 (b)
3 shows a printing unit configuration in the case where a toner image is transferred to an intermediate transfer body on the left side surface and the upper portion of the printing unit 2, respectively. In the printing unit 2, a recording body 21, which is a photosensitive body negatively charged by a charger 22, rotates clockwise to form a negative electrostatic latent image with a laser beam 24 emitted from an optical system 23, and then a developing unit. Transported to
The developing device 25 has a magnetic carrier and a negatively charged toner 2.
The electrostatic latent image is developed by the developing roller 252 of the developing device 25 to form a toner image 253 on the surface of the recording medium 21. The toner image 253 is electrostatically transferred to the intermediate transfer member 3 by the positive corona discharge of the transfer device 26. The residual charge on the surface of the recording medium 21 is removed by the eraser 27, and the residual toner is removed by the cleaner 28. In the present printing unit configuration, the developing device 25 is disposed on the lower portion and the side surface of the recording body 21 so that the recording material and the intermediate transfer body are not stained by toner or carrier dropped from the developing device. This is a great advantage in terms of the reliability and maintainability of the printing unit as compared with the case where the printing unit is installed on the upper part of the printer 21.

A first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a schematic configuration of a full-color electrophotographic apparatus 1 using continuous paper of the present invention. For simplicity,
In the figure, each printing unit has a recording medium 2 shown in FIG.
1, only the developing device 25 and the transfer device 26 are described. Four printing units 2 each having cyan, magenta, yellow, and black toner and rotating in the clockwise direction of the recording medium 21 are arranged in the vertical direction. A belt-like intermediate transfer body 3 is stretched on one side (the left side in this embodiment) of the printing units 2 arranged in the vertical direction by rollers 6 provided up and down. Intermediate transfer member 3
Rotates counterclockwise to rotate the toner image 25 on the surface of the recording medium 21.
3 are sequentially superimposed and transferred to form a color toner image 254.
To form On the other side (the right side in the present embodiment) of the printing units 2 arranged in the vertical direction, the continuous paper 7 which is a folded paper with a perforated hole is pulled out from the supply unit 71 and conveyed upward by the tractor 72. After transferring the color toner image 254 on the intermediate transfer body 3 by the color image transfer unit 261 on the intermediate transfer body 3, the continuous paper 7 is reversed in the transport direction by the reversing roller 61 and passes through the paper buffer means 73. The image is fixed by the fixing device 4 installed on the other side (the right side in the present embodiment) of the printing units 2 arranged in the vertical direction, and is stored in the paper storage unit 74. Fixing device 4
Consists of a heating plate as a contact-type preheater 41 for heating by contacting the heat roll 42 and the continuous paper 7. Paper buffer means 73 swinging around a fulcrum by a spring mechanism
Is controlled so as to absorb the slack of the paper due to the difference in the conveying speed of the continuous paper 7 between the heat roll 42 and the tractor 72 and to apply a constant tension to the paper.
1 keeps good contact.

[0007] The first feature of this embodiment is that the vertically arranged 4
The configuration of the printing units is the same. This is a great advantage in comparison with a method in which the printing units are not equivalent in terms of stability of print image quality, reliability and maintainability of the printing unit, and apparatus cost. A second feature of the present embodiment is that a developing device is provided below the recording body to transfer the toner image to the intermediate transfer body on the left side surface of the recording body rotating clockwise. If the recording body rotates counterclockwise and the image is transferred on the left side of the recording body as well, a developing device must be installed above the recording body on mounting. It is very difficult in design to install a large developing device having a plurality of developing rollers. The third feature of the present embodiment is that the reversing roller for reversing the transport direction, the paper buffer means, and the preheater are used until the paper after the color toner image transfer in the paper transport path is fixed by the heat roll. The point is that the sheet is in contact with the surface opposite to the unfixed surface of the toner image. For example, in a paper conveyance path where an unfixed transfer toner image contacts a conveyance roller, etc., the transfer toner image is used as a conveyance roller to prevent the transfer toner image from being disturbed by this contact and to prevent toner from adhering to the conveyance roller. It is necessary to use a so-called bias roller to which a voltage having the same polarity as the charge of the toner is applied. In this case, advanced technology such as the configuration, material, voltage application method, and cleaning method of the bias roller is required, which is a considerable disadvantage in cost and reliability. As described above, according to the electrophotographic apparatus of the present embodiment, in an electrophotographic apparatus that performs color printing on continuous paper using a tandem system, adaptability to a wide variety of papers caused by using an intermediate transfer member, In addition to the advantages of image quality stability and paper running stability, all printing units are equivalent, high-speed development is possible, no special equipment such as bias rollers is required, and cost, equipment reliability, usability, and printing quality are high. It has the advantage of being superior.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, the main difference from the first embodiment is that the belt-shaped intermediate transfer member 3 rotates while forming a right-angled triangle having a horizontal plane at the bottom. Two printing units 2 are arranged in the vertical direction and two in the horizontal direction. The two printing units 2 arranged vertically are the first
The toner image 253 is transferred to the intermediate transfer body 3 on the left side of the recording body 21 with the same configuration as that of the embodiment, and the two printing units 2 arranged in the horizontal direction 3 is transferred to the toner image 253.

A first feature of this embodiment is that the height of the entire apparatus is reduced because the printing units are arranged in a triangular shape along the intermediate transfer member. When printing at high speed, individual printing units become large, and the problem of increasing the size of the entire apparatus becomes serious. In particular, the printing unit
The configuration of the first embodiment has a problem that it is difficult to replace the consumables of the uppermost printing unit and to adjust and maintain the apparatus. Therefore, the apparatus configuration of this embodiment has a feature that it is more suitable for high-speed printing. A second feature of this embodiment is that the belt length of the consumable intermediate transfer member is shorter than that of the first embodiment. To print on continuous paper, the intermediate transfer body must be seamless, but in general, a seamless belt with a long perimeter is difficult to manufacture and the price is high. A great advantage in cost.

Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 4, the main difference from the second embodiment is that a drum-shaped intermediate transfer body 3 is used. Two printing units 2 are arranged in a substantially vertical direction and two in a substantially horizontal direction.

The first feature of this embodiment is that since the intermediate transfer member is a drum, belt meandering control, which is necessary for a belt-like intermediate transfer member, is not required. Therefore, there is an advantage that the alignment of the toner image, which greatly affects the image quality of the full-color image, can be performed with high accuracy. The second feature of the present embodiment is that since the consumable intermediate transfer body 3 has a drum shape, the exchange of the intermediate transfer body 3 is easy, and the driving mechanism of the intermediate transfer body 3 is simple. It is in the point. Therefore, there is an advantage that the apparatus reliability, cost, and maintainability are excellent.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that the second embodiment has a symmetrical configuration with the first printing station comprising a combination of the printing unit and the intermediate transfer member in the first embodiment shown in FIG.
Is installed on the other side (the right side in the present embodiment) of the first printing station to realize double-sided printing. The color toner image 254 on the surface of the intermediate transfer member 3 of the first printing station 11 is conveyed from the lower side to the upper side of the upper part of the intermediate transfer member 3 by pulling out the other side of the first printing station 11 from the paper supply unit 71. The transfer direction of the continuous paper 7 is reversed after being transferred to the front side of the continuous paper 7 which is a roll paper having a feed hole to be fed, and the second intermediate transfer body 31 formed on the second intermediate transfer body 31 of the second printing station 12 is inverted. The charging polarity of the color toner image 255 of the second
After being inverted from negative to positive by the positive corona discharge of No. 3, the image is transferred to the back surface of the continuous paper 7 at the upper part of the second intermediate transfer body 31 by the negative corona discharge of the second color image transfer unit 262. Next, the unfixed color toner images formed on both sides of the continuous paper 7 are transferred to the heat roll 42 installed on the other side (the right side in this embodiment) of the second printing station 12.
And the continuous paper 7 is stored in the paper storage unit 74.

According to this embodiment, as in the first embodiment, the configuration of all the printing units is essentially the same, the developing device is installed below the recording medium, and the unfixed color toner image is formed. There is an advantage in that double-sided color printing on continuous paper is possible while maintaining the feature that it does not come in contact with other members until it is fixed by a heat roll having a heat source to both rollers. In this embodiment, the second printing station 1
In FIG. 2, since the same toner as that of the first printing station 11 is used, the charging polarity is inverted on the surface of the second intermediate transfer body 31, but the toner of the opposite polarity to that of the first printing station 11 is used. In this case, it is unnecessary to invert the charging polarity of the second color toner image 255.

Next, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 6, the main difference from the fourth embodiment is that a drum-shaped intermediate transfer body 3 is used.

According to this embodiment, a full-color double-sided printing apparatus for continuous paper has the advantages that the height of the apparatus is kept low and the image quality, apparatus reliability, cost and maintainability are excellent.

[0016]

As described above, according to the present invention, in a color printing electrophotographic apparatus using a tandem system in which a plurality of printing units are arranged, a developing device is used for a recording medium so as to be adapted to high-speed printing. There is an effect that single-sided and double-sided color printing can be performed on continuous paper using an intermediate transfer member in a configuration where the intermediate transfer member is installed below or on a side surface and does not come into contact with other members until an unfixed color toner image is fixed by a heat roll.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electrophotographic apparatus for single-sided printing showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of a printing unit used in the present invention.

FIG. 3 is a schematic diagram of an electrophotographic apparatus for single-sided printing showing an embodiment of the present invention.

FIG. 4 is a schematic view of an electrophotographic apparatus for single-sided printing showing an embodiment of the present invention.

FIG. 5 is a schematic view of an electrophotographic apparatus for double-sided printing showing an embodiment of the present invention.

FIG. 6 is a schematic diagram of an electrophotographic apparatus for double-sided printing showing an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrophotographic apparatus, 2 ... Printing unit, 3 ... Intermediate transfer body, 4 ... Fixing device, 7 ... Continuous paper, 11 ... First printing station, 12 ... Second printing station, 21 ... Recording body, 25 ... Developing device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 G03G 15/16 15/20 101 15/20 101

Claims (6)

[Claims] A color image is formed by sequentially transferring a toner image formed by a toner of a two-component developer onto a recording body of a plurality of printing units onto an intermediate transfer body, and forming a color image on the intermediate transfer body. In an electrophotographic apparatus for performing color printing by transferring again to continuous paper, a part or all of a plurality of printing units are arranged in a substantially vertical direction, and an intermediate transfer body is printed on one side of the printing units arranged in a substantially vertical direction. , So that the toner image formed on the recording body of the printing unit is sequentially transferred to the intermediate transfer body to form a color image, and the printing is arranged in a substantially vertical direction. After transferring the color image on the surface of the intermediate transfer body near the upper portion of the intermediate transfer body to the continuous paper conveyed from the bottom to the upper side on the other side of the unit, the conveyance direction of the continuous paper is reversed, and a plurality of printing units are added. Electrophotographic apparatus, characterized by fixing by installing the fixing device on the side of. 2. A printing apparatus according to claim 1, wherein a part of the plurality of printing units arranged in the substantially vertical direction is installed substantially horizontally so as to intersect the plurality of printing units arranged in the substantially vertical direction at a substantially right angle below. The electrophotographic apparatus according to claim 1, wherein: 3. The electrophotographic apparatus according to claim 1, wherein the plurality of printing units are four printing units corresponding to four color toners of cyan, magenta, yellow, and black. 4. The electrophotographic apparatus according to claim 1, wherein the intermediate transfer member has a drum shape. 5. The electrophotographic apparatus according to claim 1, wherein the fixing device includes a pre-heater including a heat roll and a contact-type heating plate. 6. A first unit comprising a printing unit and an intermediate transfer member.
A second printing station symmetrical to the printing station is installed on the other side of a plurality of printing units arranged substantially vertically, and a color image on the surface of the intermediate transfer body of the first printing station is transferred to the intermediate transfer body. The transfer direction of the continuous paper after transferring to the other side of the first print station in the vicinity of the upper part of the continuous paper, which is conveyed from the bottom to the top between the first print station and the second print station. And transfer the color image formed at the second printing station to the back side of the continuous paper near the upper portion of the intermediate transfer body at the second printing station, and then install the other side of the second printing station. The electrophotographic apparatus according to claim 1, wherein the image is fixed by a fixing device.