JPS6314169A - Image recording device - Google Patents

Abstract

PURPOSE:To prevent images of a multiple print from shifting in position by providing a heating means which heats a form before the 1st transfer by a transfer means. CONSTITUTION:A heating roller 13' is equipped with a heater 14' and heats the reverse surface of a supplied form, which is conveyed while pressed. A resist roller 3 conveys the form carried by the heating roller 13 to a transfer part A in synchronism with a recording image formed on a photosensitive drum 7. The heating roller 13' before printing heats the reverse surface of the form and a fixing roller 13 after the printing heats the top surface of the form. Thus, water is removed uniformly from the top and reverse surfaces of the paper to prevent the form from curling, thereby facilitating the conveyance of the form.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image recording apparatus that circulates paper supplied from a paper feed cassette and forms an image on the paper.

(Prior Art) In general, a single image recording apparatus forms a composite image by circulating paper supplied from a paper cassette and performing development and fixing on the paper multiple times (multiple printing). In this case, a red image is printed in the first development and fixing, for example, and a black image is printed in the second development and fixing, thereby obtaining a two-color composite image.

Conventionally, the above-mentioned printing is performed by attaching, for example, red toner to paper and thermally pressing the toner with a heating roller.

(Problems to be Solved by the Invention) When the toner is thermocompression bonded, the moisture contained in the paper evaporates due to the heat of the heating roller, and for example, A4 paper shrinks by 2 to 3 cm. occurs. For this reason, there was a problem in that the second and subsequent images were shifted from the first image on the paper surface.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image recording device that can prevent image shift during multiple printing.

(Means for Solving the Problems) In order to solve the above problems, the present invention is provided with heating means for heating the paper before the first transfer. (Function) In the above structure. Therefore, before the first development is performed, the paper is heated by the heating means, and this heating causes the paper to shrink. After this shrinkage, the image is transferred.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic sectional view of an image recording apparatus according to the present invention.

In the figure, 28 is a first paper feed cassette, and the paper (not shown) placed in this cassette 28 is fed to a heating roller 13'', which will be described later, by a paper feed roller l and a conveyance roller 2.29 is a large paper feed cassette. In the capacity paper deck, sheets (not shown) stored in this deck 29 are fed to a heating roller 13'' by a sheet feeding roller 1' and a conveying roller 2'. One of the first paper feed cassette 28 and paper deck 29 is selectively selected to supply desired paper.

Reference numeral 13' denotes a heating roller as a heating means, which is equipped with a heater 14', heats the back side of the supplied paper, and conveys the paper while applying pressure. Reference numeral 3 denotes a registration roller, which conveys the sheet conveyed by the heating roller 13 to the transfer section A in synchronization with the recorded image formed on the photosensitive drum 7.

23 is a semiconductor laser, which is driven by a first image signal generated from a host computer (not shown). The laser beam emitted from this semiconductor laser 23 is scanned by a rotating polygon mirror 24 driven by a scanner motor 25, and exposes the photosensitive drum 7 via a reflecting mirror 26. An electrostatic latent image is formed on the photosensitive drum 7 by this exposure. This electrostatic latent image is transferred to the developing unit 6 or 6'.
This visible image is transferred to the transfer high-voltage charger 1.
0 onto the paper conveyed to the transfer section A. 9
1 is a high-voltage charger, and 11 is a drum cleaner. In addition, the photosensitive drum 7, the negative high voltage charger 9, the developing device 6.6',
An image forming section is constituted by a transfer high voltage charger 10 and the like.

The paper onto which the image has been transferred is sent to a fixing device (fixing means) B by a conveyor bell (12). This fixing device B consists of a fixing roller 13 and a heater 14 installed therein, and the surface of the fixing roller 13 is temperature-controlled to a temperature that allows fixing. A fixing cleaner 15 removes dirt from the surface of the fixing roller 13. The paper fixed by the fixing device B is sent to the paper bus selector 18 by the conveyance roller 16. The paper path selector 18 selects the destination of the paper from the paper output tray 30.
or the intermediate tray 21. This paper path selector 18 outputs the paper to the intermediate tray 21 via conveyance rollers 19 and 20 when multiple printing is to be performed, and to the paper output tray 3° via the conveyance roller 17 for the paper on which multiple printing has been completed. Paper.

The paper stored in the intermediate tray is fed for the second printing by the paper feed roller 22, and after the print is fixed by the same process as the first printing, the paper is transferred to the paper bus selector 18. The paper is ejected to the paper ejection tray 30.

4 is a black developing device containing black toner, and 5 is a red developing device containing red toner. A solenoid (not shown) selectively moves the developing roller 6 or 6' close to the photosensitive drum 7. do. As a result, when obtaining a black printed image, the developing roller 6 is brought close to the developing roller 6, and when obtaining a red printed image, the developing roller 6' is brought close to the developing roller 6. In this way, in the above-described printing process, the first printing is performed in black and the second printing is performed in red, thereby creating a two-color printed image (composite image).

A beam detector 27 is arranged at a scanning start position on a scanning line formed by laser beam irradiation by the rotating polygon mirror 24, and generates a BD pulse as a synchronizing signal in the horizontal direction of the image for each scan of the laser beam. A host computer (not shown) transmits an image signal in synchronization with the BD pulse signal.

FIG. 2 is a diagram illustrating the effect of the present invention on printing misalignment when multiple characters are printed.

FIGS. 2(a) and (b) are images of multiple printing by the conventional and inventive laser beam printers, and are examples in which a mark is printed as the first printing and a character is printed as the second printing. be.

In the conventional example shown in Figure (a), the printing process is in the order of first printing → heating → second character printing → heating, so the moisture in the paper is removed during the first heating. Most of the paper is taken away and the paper shrinks, and then the second printing is performed, resulting in misalignment of the printing position between the markings and the characters.

In the example according to the present invention shown in FIG. 6(b), the printing process is in the order of heating → 11th cotton printing → heating pass 2nd character printing → heating, and the heating process is performed before the printing process. Therefore, the first printing is performed after the paper has completely shrunk due to the first heating, so the shrinkage of the paper due to subsequent heating is very small and there is little printing deviation.

In the above embodiment, a heating means 13' separate from the conventional fixing roller 13 is added as a heating means, but it is not necessary to do so. For example, in the conventional configuration, printing may not be performed. It goes without saying that the same effect can be obtained by passing the paper through the conventional fixing roller 13 in the first pass and then performing multiple printing.

It is also clear that the printing deviation between the front and back sides can be corrected not only in multiple printing but also in single-sided printing.

As mentioned above, in this embodiment, the heating roller 13'' before printing is
In this method, the back side of the paper is heated, and after printing, the fixing roller 13 heats the top surface of the paper. This is 1
Water is removed evenly from the front and back sides of the paper, which has the effect of preventing the paper from curling and making it easier to transport the paper. That is, since both sides of the paper are heated by the heating means and the fixing means, moisture is evenly removed from both sides. Therefore, the paper is conveyed without curling, and jams are prevented from occurring.

Furthermore, since the paper is heated and pressurized to evaporate water in the paper before transfer and separation, the resistance of the paper during the first printing is the same as that during the second printing. Therefore, there is an effect that there is no need to change the transfer/separation conditions between the first side and the second side.

(Effects of the Invention) As described above, according to the present invention, since multiple printing is performed after the paper is shrunk by the heating means, there is no possibility of print misalignment due to shrinkage of the paper as in the conventional method.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an image recording apparatus according to the present invention, and FIGS. 2(a) and 2(b) are explanatory diagrams of printed images printed on paper. Explanation of symbols 6.6'...Developer 7...Photosensitive drum 10.
...Transfer high-voltage charger 13.13'...Heating roller 28.29...Paper feed cassette, +lr-, r'(迭'2nd factor <b>

Claims (2)

[Claims] (1) In an image recording device that circulates paper supplied from a paper feeding means to a transfer means and a fixing means to form an image on the paper, the paper is heated before the first transfer by the transfer means. An image recording device characterized by comprising a heating means. (2) The image recording apparatus according to claim 1, wherein the heating means heats a surface of the paper opposite to the surface heated by the fixing means.