JPH01270068A - Paper cooling device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To reduce power consumption and to improve cooling efficiency by forming the duct of a cooling fan so that cooling wind always blows to the upper part of folded paper. CONSTITUTION:The cooling fan 5 is attached to an opening part 3b on a side opposite to the opening part 3a of the duct and the cooling wind from the fan 5 blows from the opening part 3a. The folded surface 1a of paper, at the time of printing, is kept in the same height as that of the upper surface 3c of the opening part 3a. Therefore, in virtue of the wind pressure of the cooling wind which blows out of the opening part 3a, the paper 1b in a part facing to the opening part 3a becomes to float and gaps are formed between the pages of the paper 1b. The cooling wind flows through the gaps, thereby cooling the paper 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a paper cooling device for an electrophotographic printer for cooling printed paper after fixing in a thermal fixing printer.

[Background of the invention]

2. Description of the Related Art In electrophotographic printers, thermal fixing is widely used as a method for fixing toner forming characters and figures on printing paper, in which the paper is heated to melt and fix the toner on the paper. The fixed paper is stored in a stacker (paper folding device)
It is folded and stored. At this time, if the heat-fixed paper is folded without being cooled sufficiently and the temperature of the paper after folding is higher than the glass transition point of the toner, the toner will be absorbed in the areas where the characters and figures on the facing printing surfaces overlap. When the printed surface is opened after a certain period of time, the toner on the printed surface may peel off and some of the text, characters, or graphics may be missing. This GL elephant is called a toner stick.

This will seriously impede the print quality of the printer.

In order to prevent the occurrence of toner stick, the paper heated during fixing may be cooled to lower the paper temperature to below the glass transition point of the toner. Up until now, paper has been cooled using natural cooling or forced cooling using small fans or blowers, but ultra-high-speed printers with printing speeds of approximately 15,000 lines/min have fast paper running speeds, so paper The time for cooling becomes shorter, and sufficient cooling cannot be achieved. For this reason, it is necessary to lengthen the paper path between the fuser and the stacker and install large fans and blowers to strengthen paper cooling, which is a factor that hinders the miniaturization, labor savings, and cost reduction of printers. There is.

FIG. 4 shows an example of the paper cooling device according to the prior art described above. The printing paper 1 heated and fixed by the preheater 10 and the heat roll 8 is forcibly cooled by the cooling air blown out from the cooling blower 11, and then folded by the paddle 4 and deposited on the table 6. In the case of a high-speed printer in which the speed of the paper 1 passing between the cooling blowers 11 is high, in this conventional type cooling device, the time during which the paper 1 can receive the cooling air is shortened, and a sufficient cooling effect cannot be obtained. Therefore, in order to prevent the occurrence of toner stick, it is necessary to provide cooling with a large fan or blower commensurate with the paper traveling speed. This has led to problems such as an increase in the size of the device, device weight, power consumption, and manufacturing cost.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a paper cooling device that is small, lightweight, inexpensive, consumes little power, and has high cooling efficiency.

[Summary of the invention]

The present invention provides a stacker with a small cooling fan equipped with a duct having an opening in a horizontally long rectangular shape, and blows cooling air horizontally from the width direction of the folded sheets to the top of the folded sheets, thereby creating a gap between the sheets. Focusing on the fact that cooling air passes through the gaps between folded paper sheets and allows cooling air to be applied to the paper for a long time, improving cooling efficiency, we designed the cooling fan duct so that the cooling air always hits the top of the folded paper. shape and mounting position,
This is a devised version of the paper guide in the paper width direction.

[Embodiments of the invention]

As a specific embodiment of the present invention, FIGS. 1, 2, and 2 show the overall configuration of a paper cooling device, and FIG. 3 shows its operation.

Paper guide 2 that can slide according to the width of printing paper 1
A duct 3 having an oblong rectangular opening 3a is connected to a paddle 4.
It is installed slightly below the center of rotation. A cooling fan 5 is attached to an opening 3b on the opposite side of the duct opening 3a.
a is narrowly narrowed. Cooling air from the cooling fan 5 is blown out from the duct opening 3a. On the other hand, the print paper after fixing is folded by the action of the paddle 4 and stacked on the stacker table 6. The stacker table 6 descends when a certain amount of paper l is deposited, and the height position of the folding surface 1a of the printing paper is always maintained at a position slightly below the center of rotation of the paddle 4.

The paper cooling effect during printing in such a configuration will be described below. As shown in FIG. 3, the paper folding surface 1a during printing is maintained at the same height as the upper surface 3c of the duct opening 3a. Therefore, due to the pressure of the cooling air blown out from the duct opening 3a, the portion of the paper 1b facing the duct opening 3a is lifted up, creating a gap between the pages of the paper 1b. The paper 1 is cooled by the cooling air flowing through this gap. This cooling method has the following advantages. 6 First, while the paper 1 is folded and passes from the duct 1 to the upper IC of the opening to the lower surface 1d of the duct opening (the paper is at the height of the duct opening) Only h! A overlapped time) Always receives cooling air. Therefore, the cooling time is much longer than in the conventional cooling system, in which the paper can receive cooling air only instantaneously, as shown in FIG. Due to this ability to receive cooling air for a long period of time, even if a small, low-output cooling fan is used, cooling can be performed with high cooling effect.

In addition, since the cooling fan 5 and duct 3 are attached to the paper guide 2 which can be slid according to the width of the printing paper, the distance d between the duct opening and the paper is uniquely determined, and cooling can be performed efficiently regardless of the paper type. .

Next, since the cooling air is applied only to the folded portion of the paper, the wind pressure does not affect the paper during folding, allowing for stable folding and fewer paper jams in the stacker.

In the above embodiment, the position of the duct 1-3 in the height direction is fixed, but as shown in FIG. The same effect can be obtained by moving the duct 3 and the cooling fan 5 up and down along the paper guide 2 using the interlocking keyer 13. In the above embodiment, the duct 3 and the cooling fan 5
is placed on the back side of the printing paper 1 when viewed from the operator side, but it may be placed on the near side of the operator.

Further, instead of using the cooling fan 5, a duct may be used to take in cooling air from outside the stacker.

〔Effect of the invention〕

According to the present invention, even a small and lightweight cooling device can provide a sufficient cooling effect without causing toner stick, making it possible to reduce the size, weight, and price of printers and reduce power consumption6.

[Brief explanation of the drawing]

FIG. 1 is a front view of a paper cooling device showing an embodiment of the present invention, and FIG. 2 is a side view of the same. FIG. 3 is an enlarged side view illustrating the invention in detail. FIG. 4 is a front view showing a conventional paper cooling device to which the present invention is applied. FIG. 5 is a side view showing an application example of the present invention. In the figure, la is a printing paper folding surface, 2 is a paper guide, 3a is a duct opening, and 5 is a cooling fan. Name of patent applicant Hitachi Koki Co., Ltd. Sait Yamasai 20 3rd I! 1 4th I21

Claims (1)

[Claims] 1. In a paper cooling device that cools printing paper after fixing, a duct is placed opposite the upper side of the printing paper stacked in the paper folding device in the width direction, and cooling air is directed in the width direction of the printing paper. A paper cooling device for an electrophotographic printer characterized by being applied to the upper side of the printer. 2. Consisting of a width direction paper guide installed in the paper folding device and capable of sliding in the paper width direction, a duct held at one end of the paper guide, and a blower attached to the opening at the other end of the duct. A paper cooling device for an electrophotographic printer as claimed in claim 1. 3. A paper cooling device for an electrophotographic printer according to claim 1, wherein the duct shape of the paper facing surface is formed by a horizontally long rectangular opening.