JP2001122513A - Paper sheet folding device for printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing device capable of preventing the generation of abnormality in carrying due to the cooling air even in case of using various size or various ream weight of continuous paper sheets and capable of securely preventing the generation of toner stick phenomenon due to a shortage of the cooling. SOLUTION: An opening part of a duct 34 of a paper sheets cooling device is provided opposite to a side surface corresponding to the paper sheets length of the paper sheets piled on a table, and this opening part of the duct 34 is provided with shutter mechanisms 35, 36 capable of changing the opening area of the opening part of the duct 34 in response to the paper sheets length of the printing paper sheets to be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus in which a cooling air is supplied to a printing sheet on which a toner image has been fixed by a heat fixing method so that the printing sheet is cooled and then folded.

[0002]

2. Description of the Related Art In an electrophotographic printer, as a method of fixing a toner image on a printing sheet, thermal fixing in which the sheet is heated and the toner on the sheet is melted and fixed is widely used. When long continuous paper is used as the printing paper, the paper sent from the fixing device is folded alternately on the front and back sides and stacked on a table.

When the heat-fixed sheets are folded in a state where they are not sufficiently cooled, and are stacked on a table, the toners on the opposed printing surfaces are fused together.
After printing, when the printing surface is opened, the toner on the printing surface may peel off and part of characters and figures may be missing. This phenomenon is called a toner stick, and is a serious obstacle to print quality.

It is known that the occurrence of the above-mentioned toner stick can be prevented by cooling the sheet heated in the fixing step and lowering the sheet temperature below the glass transition point of the toner. For paper cooling, natural cooling and forced cooling with a small fan or blower have been performed.

[0005]

In recent years, continuous paper printing apparatuses of this type have been constructed so that one apparatus can handle several sizes of paper. It is desired to realize a printing apparatus capable of efficiently cooling according to the continuous paper amount.
That is, in the related art, since the flow rate and the blowing range of the cooling air from the sheet cooling device are always constant regardless of the sheet size, for example, when using a sheet having a short sheet length, the blowing by the blower constituting the sheet cooling device is performed. The range becomes wider than in the case of a long sheet, and the air volume becomes too strong. As a result, the sheet flaps, the folding of the sheet becomes unstable, and a sheet conveyance abnormality may be caused.

Accordingly, an object of the present invention is to prevent the occurrence of a toner stick phenomenon due to insufficient cooling without causing a transport abnormality due to cooling air even if continuous paper of various sizes or various paper continuous amounts is used. It is an object of the present invention to provide a printing apparatus capable of performing the above.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device for applying at least a heating effect to a printing paper holding a toner image and fixing the toner image to the printing paper, and a printing device fed from the fixing device. In a printing apparatus including a sheet folding device that folds sheets and stacks and holds the sheets on a table, and a sheet cooling device that supplies cooling air to the print sheet sent from the fixing device, a duct opening of the sheet cooling device is provided. The duct opening is provided so as to face the side surface corresponding to the sheet length of the stacked sheets stacked on the table, and the opening area of the duct opening is varied in accordance with the sheet length of the printing sheet to be used. This is achieved by providing a shutter mechanism.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

First, an overall configuration of a printing apparatus (a laser beam printer using an electrophotographic system) to which the present invention is applied will be described with reference to FIG.

In FIG. 4, reference numeral 1 denotes a laser beam printer, and the photosensitive drum 21 starts rotating in the direction of an arrow based on a printing operation start signal from a controller 22 of the printer.
The photosensitive drum 21 rotates at a speed corresponding to the printing speed of the laser beam printer 1, and continues to rotate until the printing operation ends. When the photosensitive drum 21 starts rotating, a high voltage is applied to the corona charger 2, and the surface of the photosensitive drum 21 is uniformly charged with, for example, a positive charge.

The rotary polygon mirror 3 is a laser beam printer 1
As soon as the power is turned on, the motor starts rotating, and the constant-speed rotation is maintained with high accuracy while the power is turned on. A laser beam output from a light source 4 composed of a semiconductor laser, a light emitting diode, or the like is reflected by the rotating polygon mirror 3 and irradiated while scanning the photosensitive drum 21 through the fθ lens 5.

When the character data or graphic data converted into the dot image is sent from the controller 22 to the laser beam printer 1 as an on / off signal of the laser beam, the portion where the laser beam is irradiated on the surface of the photosensitive drum 21 and the irradiation are performed. And a so-called electrostatic latent image is formed. When the photosensitive drum area holding the electrostatic latent image reaches a position facing the developing device 6, toner is supplied to the electrostatic latent image, and a portion on the photosensitive drum 21 where the charge on the photosensitive drum 21 has disappeared due to the irradiation of the laser beam. For example, the toner charged to a positive charge is attracted by static electricity,
A toner image is formed thereon.

The continuous paper 7 stored in the paper hopper 11 is rotated by the paper transport tractor 8 in synchronization with the timing at which the toner image of the print data formed on the photosensitive drum 21 reaches the transfer position. And transfer device 1
It is transported between 0.

The toner image formed on the photosensitive drum 21 is sucked onto the paper 7 by the action of the transfer unit 10 which applies a charge of the opposite polarity to the toner image on the back side of the paper 7.

The paper 7 set in the paper hopper 11 in this manner is transferred to the paper transport tractor 8 and the transfer device 1.
0, the sheet is conveyed to the fixing device 12 via the sheet conveying tractor 9 and the buffer plate 24. The sheet 7 arriving at the fixing device 12 is preheated by a preheater 13 and then heated and pressed by a nip formed by a pair of fixing rollers including a heating roller 14 having a heater lamp 25 and a pressure roller 15. The toner image is nipped and conveyed, and the toner image is fused and fixed on the sheet 7.

The sheet 7 sent out by the heating roller 14 and the pressure roller 15 is sent out to the stacker table 19 side by the sheet sending-out roller 16.
The swinging fins 17 are alternately folded along the perforations by the swinging operation of the swing fins 17, and the folding state is adjusted by the rotating paddle 18.
Stacked on top of 9. The area that has passed the transfer position of the photosensitive drum 21 is cleaned by the cleaning device 20, and is prepared for the next printing operation.

In FIG. 4, reference numeral 23 denotes a display screen for displaying information based on the state of the laser beam printer 1 during a printing operation. Further, the above-described buffer plate 24 is provided between the paper transport tractor 9 and the fixing rollers 14,1.
This is to absorb the slack or tension generated in the sheet 7 when the sheet conveyance speed difference occurs between the sheets 5.
Reference numeral 26 denotes a web member provided so as to be in contact with the surface of the heating roller 14 and to be able to be wound, and is used for cleaning the surface of the heating roller 14 and applying a release agent to the surface of the heating roller 14. Things.

Next, the configuration of the sheet cooling device will be described in detail with reference to FIGS. 1, 2 and 3.

In FIGS. 1, 2 and 3, the direction of arrow X corresponds to the length of the printing paper, and the direction of arrow Y corresponds to the width of the printing paper. The blowers 27, 28, and 29 are provided so as to face the side surfaces corresponding to the sheet lengths of the stacked sheets stacked on the table 19.

As shown in FIG. 2, the air introduced into each of the blowers is taken in from the lower part of the outer cover 30 on the front side of the printing apparatus, passes through an outside air intake duct 31, and is provided with three blowers 27 near the upper surface of the stacking paper. , 28, 29, the outside air blown from the front side of the sheet width, which is the printing reference position in the sheet width direction, cools the sheet and is heated by the sheet heat,
The air is discharged to the outside through a rear exterior cover 33 by a blower 32 arranged on the rear side.

With the above configuration, the distance between the end face in the sheet width direction and the duct 31 becomes constant irrespective of the sheet width, and it is possible to prevent the problem that the cooling air is diffused by the sheet width and the cooling efficiency is reduced. Further, since the cooling air is taken in from the lower part of the front side outer cover 30, the design of the apparatus is not deteriorated. Further, since the outside air warmed by the paper heat is efficiently discharged to the rear side and no warm air is trapped inside, the toner remaining on the paper 7 heated by the fixing device fuses the toner on the overlapping printing surfaces, It is possible to prevent the printing surface from being stained.

Further, the three blowers 27, 28, 29
The necessity of the operation can be controlled by the paper length, and when printing is performed using a paper having a short paper length, by operating only the blower 27, the air is not blown over a wider area than necessary. In addition, it is possible to suppress the fluttering of the sheet and to stably fold the sheet, thereby preventing the occurrence of the conveyance abnormality.

When printing is performed using a long sheet, for example, by operating the blowers 27, 28, and 29 simultaneously, air can be blown to the end of the long sheet in the sheet length direction. The heat remaining on the sheet 7 heated by the apparatus can prevent the toner on the overlapping printing surface from fusing and preventing the printing surface from being stained.

In the above embodiment, the blower is 3
The case where two or three are provided has been described as an example.
The same effect can be obtained even when the number is more than one.

In front of the blower, as shown in FIG. 3, a duct 34 of the blower which is long in the paper length direction, and a shutter 3 which moves according to the paper length setting and adjusts the opening area of the duct 34.
5,36 are provided.

Therefore, when using a short sheet of paper, the opening area of the duct 34 is reduced by the shutters 35 and 36 so that only the blower 27 is operated, so that the sheet can be prevented from fluttering and can be stably folded. The occurrence of abnormalities is prevented. When long sheets are used, the opening area of the duct 34 is increased by the shutters 35 and 36, and the blowers 27, 28 and 29 are operated.
It is possible to sufficiently cool the sheet, and it is possible to prevent the toner on the overlapping printing surface from fusing due to the heat remaining on the sheet heated by the fixing device, thereby preventing the printing surface from being stained. If the air volume is controlled based not only on the opening area but also on the continuous amount of paper used (paper thickness), more stable conveyance and efficient cooling can be realized.

[0027]

As described above, according to the present invention, even if continuous paper of various sizes or various amounts of continuous paper is used, a conveyance abnormality due to cooling air does not occur, and a toner stick phenomenon due to insufficient cooling occurs. Can be provided.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a side view showing one embodiment of the present invention.

FIG. 3 is a perspective view showing one embodiment of the present invention.

FIG. 4 is an overall configuration diagram of a printing apparatus.

[Explanation of symbols]

7 ... paper, 17 ... swing fin, 19 ... table, 2
7, 28, 29 ... blower, 34 ... duct, 35, 36 ... shutter.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masaru Sawahata 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Kazuo Takano 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture F-term in Hitachi Koki Co., Ltd. (Reference) 2H033 AA15 BA10 BA29 CA16 CA17 CA53 3F108 AA01 AB04 AC03 BA04 BB32 CB24 CB43 CB45

Claims (2)

[Claims] A fixing device that applies at least a heating effect to the printing paper holding the toner image and fixes the toner image on the printing paper; and a printing paper fed from the fixing device is folded and stacked and held on a table. A sheet folding device, and a sheet cooling device that supplies cooling air to the printing sheet sent from the fixing device, wherein a duct opening of the sheet cooling device is stacked on the table. A shutter mechanism is provided to face the side surface corresponding to the sheet length of the sheet, and a shutter mechanism is provided in the duct opening to change the opening area of the duct opening according to the sheet length of the printing paper to be used. Printing device. 2. The printing apparatus according to claim 1, wherein an amount of air from said sheet cooling device is controlled based on a continuous amount of sheets.