JPH01105277A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a form from being curled in case of fixing a thin form by forming a pinch roller so as to be movable along the outside peripheral surface of a discharge roller, moving selectively it and displacing a press- contacting position of the pinch roller against the discharge roller. CONSTITUTION:A pinch roller 6 is formed so as to be movable along the outside peripheral surface of a discharge roller 5, and also, a moving means 7 for moving selectively this pinch roller 6 and displacing a press-contacting position of the pinch roller 6 against the discharge roller 5 is provided. In such a way, when a form is thin, it scarcely occurs that the form is curled along the outside peripheral surface shape of the discharge roller 5 at the time of its discharge, and on the other hand, when the form is thick, a deformation of the form which is formed in a nip part of a heating roller 2 and a pressure roller 3 can be straightened by the discharge roller 5 and the pinch roller 6, therefore, the fixation can be executed surely without curling the form.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fixing device used in equipment using an electrophotographic process such as an electrophotographic copying machine, facsimile machine, and printer, and particularly relates to a fixing device that is used in equipment that uses an electrophotographic process, such as an electrophotographic copying machine, a facsimile machine, and a printer. The present invention relates to an improvement of a fixing device that does not cause curling of fixed paper regardless of the situation.

[Prior Art] Conventionally, in copying machines and the like that use an electrophotographic process, it is necessary to fix an unfixed toner image formed on paper to make it permanent, and the fixing methods include solvent fixing, A pressure fixing method and a heating chamber method are known.

However, the above-mentioned solvent fixing method has the disadvantage that the solvent vapor is scattered and there are many odor and hygiene problems.On the other hand, the pressure fixing method also has poor fixing performance compared to other fixing methods, and At present, pressure-sensitive toners have the disadvantage of being expensive and are not widely put into practical use.

For this reason, a heat fixing method is widely used to fix unfixed toner images, in which the toner is melted by heating and fused onto the paper.

As shown in FIGS. 4 and 5, this heating fixing device includes a heating roller (a) which is equipped with a heater inside a cylindrical core metal and has a heat-resistant resin film layer formed on its outer peripheral surface; a pressure roller (b) arranged in pressure contact with the roller (a) and having a heat-resistant elastic layer formed on the outer peripheral surface of a cylindrical core;
Heating for fixing the paper (p) having an unfixed toner image formed in the toner image transfer section (d) of the photosensitive drum (C) by passing it between the heating roller (a) and the pressure roller (b). The roller type is known, and it has higher thermal efficiency than other heat fixing methods such as thermal IE fixing methods and oven fixing methods, so it has low power consumption and high speed, and there is no risk of fire due to paper jams. It is the most widely used because there are few.

By the way, in the conventional fixing device of this type, as shown in FIG. A discharge roller (rl) and a pinch roller (r2) are disposed in pressure contact with each other, and are arranged in a tangential direction (α) of the heating roller (a) or pressure roller (b). On the other hand, the discharge roller (rl) and the pinch roller (r2) are set to face each other in the vertical direction (β) so that the contact surface between the paper (p) and the discharge roller (rl) is minimized, and the sheet is conveyed out. Even when the trailing edge of the paper (p) is heated and held between the pressure rollers (a) and (b), no load is applied to the paper (p) along the outer circumferential shape of the discharge roller (rl). In this way, the paper (p) is deformed (
In other words, methods have been adopted to prevent curling.

[Problems to be Solved by the Invention] However, when a thick paper (p) such as a postcard on which an unfixed toner image is formed is fixed in this type of device, the heating roller (a) and the pressure roller At the nip with paper (b), one side of the paper (p) is heated by the heating roller (a).
), the moisture content on both sides of the paper (p) will differ, causing a difference in the shrinkage rate on both sides of the paper (p), and - within the film, the heating roll (a) side will shrink more. . Therefore, the paper (p) may curl along the outer peripheral surface shape of the heating roller (a).

Since thick paper is stiffer than thin paper and once curled, it is difficult for it to return to its original shape naturally. When the paper (p) is ejected to the outside of the machine body via the pinch roller (r2), there is a problem that handling of the paper (p) becomes inconvenient.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems, and its object is to provide a fixing device that does not cause the fixed paper to curl, regardless of the thickness of the paper. It is about providing.

The present invention is equipped with a heating roller that is rotatably provided inside the main body of the machine, and a pressure roller that rotates in pressure contact with the heating roller, and guides the paper on which the unfixed toner image is formed. The paper is inserted between the heating roller and the pressure roller via a plate to fix the toner image of the unidentified person, and the fixed paper is ejected to the outside of the main body by a discharge roller and a pinch roller that rotate while pressing against each other. The above-mentioned pinch roller is formed to be movable along the outer circumferential surface of the ejection roller, and the pinch roller is selectively moved to adjust the position of the pinch roller in pressure contact with the ejection roller. It is characterized by providing a moving means for displacing it.

In such technical means, the heating roller is
A heater is provided inside the cylindrical core metal, and the outer peripheral surface is coated with heat-resistant resin such as polytetrafluoroethylene (PTFE), or HTV silicone rubber (Ilight
empire VulcanizationS
silicone rubber), RTV silicone rubber (Room Temperature Vulcani
A roller with high toner releasability coated with a heat-resistant elastic material such as zation 5 silicone rubber) can be used.One pressure roller is made of HTV silicone rubber, RT V silicone rubber, L
TV silicone rubber (Low Temperature
Vulcanization 5ilicone Ru
It is possible to use a material coated with a heat-resistant elastic material such as Bber) or fluororubber.

In addition, the means for forming the pinch roller so that it can move along the outer peripheral surface of the ejection roller is appropriately selected depending on the size of the fixing device and the installation position in the machine body in which this device is installed. The proximal end of the support member held at the side is rotatably attached to the rotating shaft of the discharge roller, and the proximal end of the support member is rotated by appropriate means to swing the distal end thereof. Accordingly, the pinch roller can be arranged at an appropriate position on the outer peripheral surface of the discharge roller.

On the other hand, the moving means for selectively moving the pinch roller and displacing the pressure contact position of the pinch roller with respect to the discharge roller may be, for example, a means for selectively rotating the proximal end side of the support member in the above example. can,
- For example, it is possible to use a solenoid or the like that rotates the support member through an appropriate intervening member.

Note that the guide plate that guides the paper on which the unfixed toner image is formed between the heating roller and the pressure roller is generally used to smooth out wrinkles that tend to occur across the width of the paper during paper transport. It is fixedly arranged with the tip side in the guiding direction facing upward. However, in the case of thick paper, wrinkles are less likely to occur, and the transportability of the paper deteriorates due to the increased weight, so it is advantageous for the guide plate to have a smaller inclination. Therefore, when implementing this technical means, the slope of the guide plate may be changed depending on the thickness of the paper, and in this case, the guide plate may be linked with the moving means. . However, as in the conventional case, it is of course possible to use a fixed arrangement.

Further, when implementing this technical means, an appropriate exhaust means may be provided to exhaust the heated air inside the fixing device in order to prevent malfunctions due to temperature rise inside the fixing device.

[Operation] According to the above-mentioned technical means, the pinch roller is formed to be movable along the outer peripheral surface of the discharge roller, and the pinch roller is selectively moved to bring the pinch roller into pressure contact with the discharge roller. Since a moving means for displacing the paper is provided, when fusing thin paper, the pinch roller is positioned at a position where the contact surface between the paper and the ejection roller is minimized, and the pinch roller is placed at the position where the contact surface between the paper and the ejection roller is minimized. On the one hand, when fixing thick paper, the pinch roller is placed at a position where the contact surface between the paper and the ejection roller is wide. It is possible to correct the curling of the paper at the nip between the heating roller and the pressure roller by applying a load to the paper along the outer peripheral surface shape of the paper when the paper is delivered. Become.

[Example] Hereinafter, an example in which the fixing device of the present invention is incorporated into a copying machine will be described in detail with reference to the drawings. As shown in FIG.
a guide plate (4) provided on the paper inlet side, and the heating;
A moving member (7) displaces the discharge roller (5) and the pinch roller (6) provided on the paper discharge side of the pressure rollers (2) and (3), and the guide plate (4) and the pinch roller (6), respectively. ) and its main parts are made up of.

First, the heating O-ra (2) is a cylindrical iron core metal (2) which is rotatably supported in the direction of the arrow by a drive means not shown.
1) and the thickness 36 that covers the outer peripheral surface of this core metal (21).
μm polytetrafluoroethylene heat-resistant resin layer (2
2), and an 850W (watt) halogen lamp (23) for heating the outer peripheral surface of the heating roller (2) is disposed inside the core metal (21).

On the other hand, the pressure roller (3) is disposed below the heating roller (2) and has a cylindrical SUM core (31) and a thickness of 8 surfaces covering the outer peripheral surface of the core (31). and a heat-resistant elastic layer (32) made of LSR silicone rubber, and the core metal (31) is supported for rotation in the direction of the arrow as the heating roller (2) rotates. An appropriate pressure is applied between the heating roller (2) and the pressure roller (3) by a biasing means not shown, thereby forming an appropriate nip width between the heating and pressure rollers (2>(3)). It has become so.

The guide plate (4) is made of an aluminum plate, and as shown in Figs. 1 and 2, the guide plate (4) is arranged along the length of the heating and pressure roller (2 The proximal end thereof is attached to a rotating shaft (8), and the distal end thereof swings to change the inclination gradient.

Next, regarding the discharge roller (5), see Figures 1 and 3.
As shown in the figure, a plurality of rubber rollers (50) fitted onto a shaft (9) rotated by a drive motor (not shown)
The pinch roller (6) is fitted onto the second shaft (10) and is placed in pressure contact with the rubber rollers (50) to (50), respectively, so that the pinch roller (6) is driven to rotate. A plurality of plastic rollers (60) to (
60). Further, the bracket (61) supporting the second shaft (10) has its 13th end connected to a rubber roller (50) via a bearing (not shown).
) to (50), and the tip side of the bracket (61) swings to form the plastic roller (60) that constitutes the pinch roller (6).
) to (60) can move on the outer peripheral surface of the discharge roller (5).

The movable member (7) also includes a link (70) bent into an abbreviated shape, and a second link provided between the negative end of the link (70) and the bracket (61) for the pinch roller (6). - a leaf spring (71), a second leaf spring (12) provided between the used end of the link (70) and the guide plate (4), a bent portion of the link (10) and the fixing device housing; (H)
It is composed of a spring (73) disposed between the springs (73) and a solenoid (74) attached to the second leaf spring (72), and when the solenoid (74) operates, the link (70) is activated. When moving in the direction of the arrow, the bracket (61) rotates counterclockwise and the pinch roller (6) heats up.
It moves to a position away from the pressure rollers (2) and (3) (position 1 indicated by the solid line in FIG. 1), and the guide plate (4)
) is also rotated counterclockwise on its proximal end side so that its inclination becomes smaller. On the other hand, the solenoid (74)
When the operation stops, the link (70) moves in the direction of arrow B due to the biasing force of the spring (13), and the bracket (61) and guide plate (4) rotate clockwise, causing the pinch roller (6) and The guide plate (4) is adapted to be displaced to the position shown by the broken line in FIG. The stopping positions of the bracket (61) and the guide plate (4) are regulated by stoppers (80) to (80) provided on the end side of the fixing device housing (H). .

In addition, a large number of exhaust holes (old) to (old) are provided on the wall of the fixing device housing (H) that covers the heating roller (2), as shown in FIG.
-1) A duct (H3) equipped with an exhaust fan (■2) is installed on the upper side, and a large number of exhaust holes (■4) are also provided on the side wall (11) of the copying machine body (1). The heated air inside the fixing device housing (H) can be exhausted to the outside, thereby preventing the temperature inside the device from rising.

In order to fix paper on which an unfixed toner image has been formed using the fixing device configured as described above, first, before starting the copying operation, the thickness of the copy paper is selected in advance, and a After operating the operation button to set the light mode or thick mode, turn on the start button of the copying machine.

That is, when the thin mode is set, the solenoid (14) is turned off, and the guide plate (4) and pinch roller (6) are set at the positions shown by broken lines in FIG. In this state, when the thin copy paper (p) on which the unfixed toner image is formed is conveyed to the guide plate (4) by the conveyor belt (82), the leading edge of the copy paper (p) is arranged diagonally. The paper (p) comes into contact with the guide plate (4), and the leading edge of the paper (p) is smoothed and wrinkles are smoothed out at that point, and then heated and inserted between the pressure rollers (2) and (3). Next, the toner is melted by heat transfer from heating 0-5 (3) and poured into the fibers of paper (p), and is then cooled and fixed.

Then, the fixed copy paper (0) is conveyed as the heating and pressure rollers (2) and (3) rotate, and passes through the ejection roller (5) and pinch roller (6) to the copying machine main body. (1
) is carried out to an externally provided discharge tray (81).

At this time, even if the copy paper (p) is conveyed between the discharge roller (5) and the pinch roller (6) with its rear end heated and sandwiched between the pressure rollers (2) and (3),
In the thin mode, the pinch roller (6) is arranged at the position indicated by the broken line and the pinch roller (5) is placed against the paper (p).
Since no load is applied along the outer circumferential shape of the paper (p), it has the advantage that the paper (p) is not curled.

On the other hand, when the thick mode is set, the solenoid (74) is turned on, and the guide plate (4) and pinch roller (6) are set at the positions shown by solid lines in FIG. In this state, the thick copy paper (p) on which the unfixed toner image has been formed is transferred to the guide plate (4) by the conveyor belt (82).
), guided by a substantially horizontal guide plate (4), heated, and inserted between pressure rollers (2) and (3) to be fixed.

At this time, the copy paper (p) has one side facing the heating roller (
2), and the other side is pressed by the pressure roller (3), so it is easy to curl along the outer peripheral surface shape of the heating roller (2).

However, in the thick mode, the above pinch 0-ra (6)
is arranged at the position indicated by the solid line, and a load is applied to the paper (p) along the outer peripheral surface shape of the ejection roller (5), so that the nip between the heating and pressure rollers (2) and (3) is The paper (p) has the advantage of being able to reliably prevent curling by correcting curls formed in the paper (p) section.

[Effects of the Invention] As described above, the present invention makes it difficult for the paper to curl along the outer peripheral surface shape of the ejection roller when the paper is thin when it is ejected; Since the deformation of the paper formed at the nip portion of the pressure row can be corrected by the ejection roller and the pinch roller, it is possible to reliably fix the paper without curling the paper.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view of a fixing device according to the embodiment, FIG. 2 is a partial perspective view thereof, and FIG. 3 is a discharge roller and a pinch A partial perspective view of the roller is shown, and FIGS. 4 and 5 show a conventional example. FIG. 4 is an explanatory diagram of the configuration of a copying machine incorporating a conventional fixing device, and FIG. 5 is an illustration of the fixing device. A cross-sectional view of the is shown. [Description of symbols] (1) Copying machine body (2) Heating roller (3) Pressure roller (4) Guide plate (5) Discharge roller (6) ... Pinch roller (7) ... Moving member

Claims (2)

[Claims] (1) The machine is equipped with a heating roller that is rotatably provided inside the main body, and a pressure roller that rotates in pressure contact with the heating roller, and the paper on which the unfixed toner image has been formed is passed through the guide plate to the A fixing device that is inserted between a heating roller and a pressure roller to fix an unfixed toner image, and also discharges the fixed paper to the outside of the main body using a discharge roller and a pinch roller that rotate while pressing against each other. In the fixing method, the pinch roller is formed to be movable along the outer circumferential surface of the ejection roller, and a moving means is provided for selectively moving the pinch roller to displace the pressure contact position of the pinch roller with respect to the ejection roller. A fixing device characterized in that it prevents curling of finished paper. (2) The guide plate is characterized in that the base end in the guide direction is rotatably provided, and the distal end in the guide direction is selectively movable up and down. The fixing device according to item 1.