JPH0197978A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the damage of an image and the occurrence of a jam or the like by directing an entrance guide plate to a desired guide direction in case of a transfer material of low rigidity as well as a transfer material of high rigidity. CONSTITUTION:A shake supporting shaft 10 stuck above an entrance guide plate 3 in the transfer material carrying direction, a transmission member 12 which is stuck to the shake supporting shaft 10 and transmits the shake, and a cam member 15 which is pressed against and separated from the transmission member 12 to shake the transmission member 12 are provided. The cam member 15 is operated to shake the entrance guide plate 3 vertically with the shake supporting shaft 10 as the center of the shake, and a transfer material like a sheet of ordinary paper or a thin sheet of paper and a transfer material like a thick sheet of paper or a postal card are guided to the nip position between a heat roller 1 and a pressure roller 2 at different guide angles respectively. Thus, factors of trouble at the time of fixing are eliminated to prevent the jam, creases of the transfer material, the damage of the image, or the like.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fixing device that heats and fixes an unfixed toner image onto a transfer material such as recording paper, and fixes the unfixed toner image by sandwiching and conveying the transfer material between a heating roller and a pressure roller that rotate in pressure contact with each other. The present invention relates to a fixing device that is applied to image forming apparatuses such as electrophotographic recording devices, laser recording devices, and 7-axis recording devices.

[Background of the invention]

In an image forming apparatus such as an electrophotographic recording apparatus, methods for fixing an unfixed toner image onto a transfer material such as recording paper include, for example, a solvent fixing method, a pressure fixing method, a heat fixing method, etc. Generally, a heat fixing method is often employed in which toner is melted by a heating roller and adhered to a transfer material. In this type of method, a transfer material supporting an unfixed toner image is conveyed while being sandwiched between a heating roller and a pressure roller that rotate in pressure contact with each other, and the toner is melted by the heating and pressure of the heating rollers. The image is then thermally fixed onto the transfer material. In a general heating roller type fixing device, the heating roller is located on the upper side. The heating roller has a heating means such as a heater inside a pipe-shaped metal roller, and a surface coating layer such as silicone rubber is provided on the surface of the metal roller. The pressure roller that comes into pressure contact with the heating roller is formed by wrapping, for example, silicone rubber around the circumferential surface of a core metal. The surface temperature of the heating roller is maintained at around 200° C. by heating means, and the heating roller is rotated in one direction by power. On the other hand, the pressure roller
During fixing of the transfer material, the transfer material is pressed against a heating roller from behind and rotated by the heating roller. Then, while the transfer material passes through a fixing device, the toner image is fused and fixed, and then the transfer material is discharged to the outside. An entrance guide plate is provided to guide the transfer material on which the toner image has been transferred to a pressure contact position, that is, a nip position, between the heating roller and the pressure roller. The entrance guide plate is a guide member on the entrance side of the fixing device that directs the traveling direction of the transfer material separated from the image carrier and transported by the transport system to the nip position between the two rollers. When using a relatively low-rigid transfer material such as plain paper or thin paper, set the entrance guide plate so that the leading edge of the transfer material reaches the heating roller surface slightly above the nip position of both rollers. Install. Furthermore, an upwardly convex guide portion is provided near the center of the entrance guide plate. When the leading edge of a transfer material with low rigidity, such as plain paper or thin paper, is conveyed directly to the nip position between the two rollers, the transfer material will be localized near its leading edge due to temporary resistance at the nip. This can cause wrinkles, deform the unfixed and unstable toner image, and damage it due to fusing roller abrasion. The reason why the leading edge of the transfer material reaches the heating roller side and the central portion of the entrance guide plate is formed in a convex shape is to prevent troubles when the transfer material is caught in the fixing device as described above. When the above-mentioned trouble prevention method is taken, when the leading edge of the transfer material receives temporary resistance from the nip portion of the two rollers, the area near the leading edge is formed into a loop shape to buffer the conveying force. Since the effect of providing an appropriate curl portion at the leading edge of the transfer material is obtained, the above-mentioned wrinkles are not generated in the transfer material, and therefore, damage to the image is prevented. However, in all of these methods, the transport surface of the transfer material is set at a higher position than the nip position of both rollers, and when transporting transfer material made of thin paper or plain paper with low rigidity, the above-mentioned However, when copying a thick transfer material, such as a postcard, the tip of the transfer material should be brought into contact with the circumferential surface of the heating roller at a position higher than the nip position of both rollers. However, due to its rigidity, the transfer material may not form a loop and may instead become irregularly deformed, or the surface of the heating roller and the tip of the transfer material may slip, causing the transfer material to be carried into the nip between the two rollers. This could also cause a jam. Furthermore, when the rear end of the transfer material reaches the nip position, the rear end jumps up due to the elasticity of the transfer material, comes into contact with other equipment, and disturbs the unfixed toner image.

[Problems to be solved by the invention]

The present invention has been made in view of the above points and to eliminate the drawbacks, and is applicable to both transfer materials with low rigidity such as plain paper and thin paper, and transfer materials with high rigidity such as postcards and cardboard. In addition, the entrance guide plate has a preferable guiding direction to prevent the image from being damaged or jammed due to problems that tend to occur when the transfer material with the toner image transferred is caught between the fixing rollers. It is an object of the present invention to provide a fixing device that prevents the fixing device from being damaged.

[Means to solve the problem]

The above object is to provide a fixing device in which a transfer material on which an unfixed toner image is formed is guided by an entrance guide plate to a pressure contact position between a heating roller and a pressure roller. A swinging support shaft fixed on the upstream side, a transmission member fixed to the end of the swinging support shaft and transmitting the swinging motion, and a cam member pressing against and separating from the transmission member to swing the transmission member. A fixing device characterized in that the fixing device is configured such that the inlet guide plate can be vertically swung about the oscillating support shaft by operating the cam member. achieved by

【Example】

An embodiment of the present invention is shown in FIGS. 1, 2, 3a, and 3.
Shown in Figure b. FIG. 1 shows the structure of a fixing device according to the present invention. The heating roller l is forcibly driven and rotated clockwise at a fixed position value by a power device of the main body of the image forming apparatus. The pressure roller 2 is in pressure contact with the heating roller 1 from directly below and is driven to rotate counterclockwise. A transfer material with a toner image transferred onto its upper surface is carried in from the direction of arrow A through the guide of the entrance guide plate 3 toward the pressure contact position, that is, the nip position between these rollers. The transfer material is held between both rollers and conveyed to the left. At this time, the toner image on the transfer material is melted by the heat of the heater group 4 built into the heating roller 1 and fixed onto the transfer material. The transfer material on which the toner image has been fixed is carried out from the nip between both rollers, and after the toner image is cooled and fixed, it is peeled off from the roller surface via separation claws 5 and 6, and conveyed by paper discharge rollers 7 and 8. It is designed to be discharged to the outside of the apparatus main body from the direction of arrow B. The heating roller 1 has a thickness of 0.4 m on the outside of the pipe-shaped core metal.
A silicone rubber layer with a thickness of 30 m is formed, and a layer of 30 m thick is formed on the outside.
The roller has an outer diameter of about 60 mm and is coated with a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) tube of about μm size. When manufacturing the heating roller I, for example, the above-mentioned tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is placed inside a mold having an inner diameter of 60 mm.
A method is used in which a tube is attached, a core bar with an outer diameter of 59 mm is inserted, and liquid silicone rubber is injection molded into a gap of about 0.4 mm on one side and cured by heating. The pressure roller 2 has a thickness of 6.5 mm and a hardness of 4 on the outside of the core metal.
The roller has an outer diameter of about 65 mm and is formed with a silicone rubber layer of about 0° and further coated with a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) tube. The heater group 4 built into the heating roller l includes a 1500W heater located at the center in the longitudinal direction of the heating roller l and having a length equivalent to the width of A4 size paper, and a heater group 4 on both sides of the heating roller It consists of a 600W heater with a total length approximately the same as that of the heater. The amount of heat generated is controlled by temperature detection by a contact type sensor 9 set on the surface of the heating roller 1 so that the temperature of the circumferential surface of the heating roller 1 is always maintained at around 200°C. The temperature sensor 9 is set to detect the temperature distribution at two locations, one at the center of the heating roller l and one at about 50 mm closer to the center than the end. The heating roller 1 and the pressure roller 2 are arranged so that when the heater group 4 starts to be energized by the standby of the device and the peripheral surface temperature of the heating roller 1 reaches 200°C, the pressure roller 2 moves upward. After a further 90 seconds of warm-up time, it becomes possible to fix, that is, to start copying. The heating roller 1 is built in such a way that it can be easily removed from the fixing device by removing the bearing holders at both shaft ends, so that cleaning, maintenance, etc. can be easily performed. FIG. 2 is a perspective view of the vicinity of the entrance guide plate showing an embodiment of the present invention. In the figure, lO is a swing shaft, 11 is an entrance guide mounting plate, 12 is a transmission member, 13 is an upper limit stopper,
14 is a cam support shaft, 15 is a cam member, and 16 is a cam dial. Note that the same members as in FIG. 1 are indicated by the same symbols. The swing support shaft lO is a metal round bar with an outer diameter of 6 cm and a length of about 360 mm. The support shaft IO has a member engaging portion (D-cut processing portion) at one location at the shaft end and at two locations near the center, and the transmission member 12 is fixed to the engaging portion at the shaft end. An entrance guide plate 3 is fixed to the engaging portion near the center. That is, the entrance guide plate 3 and the transmission member 12 are integrally formed via the swing shaft lO. The swing shaft lO is pivotally supported by an entrance guide mounting plate 11 fixed to the main body of the fixing device. The entrance guide mounting plate 11 is a support member having a length of approximately 37 m+a, which is formed by processing a metal plate having a thickness of 1.6+o+a into a U-shape, and pivotally supports the swinging support shaft IO. A screw hole for the fulcrum screw of the upper limit stopper 13 is threaded on the side end surface provided on one side in the longitudinal direction of the entry guide mounting plate 11, and the cam member 1
A cam support shaft 14 for pivotally supporting 5 is fixed. The transmission member 12 was formed by processing a metal plate with a thickness of 1.6 mm. One end of the transmission member 12 is fixed to the swing support shaft lO, and the other end has a contact surface for the cam member 15. The cam member 15 presses against and separates from the corresponding contact surface, and the transmission member 12
The transmission member 12 is oscillated about the oscillation support shaft lO.
The swinging motion is transmitted to the entrance guide plate 3 via the swinging support shaft lO. The upper limit stopper 13 was formed by processing a metal plate with a thickness of 1.6 mm. A fulcrum hole is bored near the center of the upper limit stopper 13, and the entrance guide mounting plate 11 is connected to the upper limit stopper 13 via a fulcrum screw.
mounted on. One end of the upper limit stopper 13 is configured to be fixed to the inlet guide mounting plate 11 at an arbitrary distance via a screw 17, and the other end is fixed to the upper end 12a of the transmission member 12. It acts to suppress and regulate the upper limit. By rotating the screw 17, the upper limit stopper 13 rotates using the fulcrum hole as a rotation fulcrum, thereby regulating the height of the upper end 12a of the transmission member 12. By doing so, the upper end of the entrance guide plate 3, which is integrally formed with the transmission member 12 via the swing support shaft lO, is similarly regulated. The cam member 15 is made of synthetic resin. The cam member 15 is integrally formed with a cam dial 16,
As the cam dial 16 rotates, it presses against and separates from the transmission member 12, causing the transmission member 12 to swing about the swing axis lO. Figures 3a and 3b are side sectional views showing the operation of the entrance guide plate. In these figures, the same members as in FIGS. 1 and 2 are designated by the same reference numerals. FIG. 3a shows an entrance guide plate 3 used to guide transfer materials such as plain paper and thin paper to the nip position of both fixing rollers.
This is the position of The cam member 15 is in pressure contact with the transmission member 12, and the transmission member 12 is pushed upward. The upper end 12a of the transmission member 12 is restricted from moving upward by an upper limit stopper 13. In this way, the installation state of the entrance guide plate 3 with respect to the nip position between the heating roller 1 and the pressure roller 2 is strictly determined, and is set to suitable conditions for fixing transfer materials such as plain paper and thin paper. Figure 3b shows the entrance guide plate 3 used to guide transfer materials such as cardboard or postcards to the nip position of both fixing rollers.
This is the position of The cam member 15 is separated from the transmission member 12, and the transmission member 12 moves downward due to its own weight. The lower surface of the entrance guide plate 3 comes into contact with a lower limit stopper lla provided on the entrance guide mounting plate 11, and the downward movement of the entrance guide plate 3 is restricted. Thus, the entrance guide plate 3 is
The installation state with respect to the nip position between the heating roller 1 and the pressure roller 2 is strictly determined, and is set to suitable conditions for fixing transfer materials such as cardboard and postcards.

【Effect of the invention】

According to the present invention, the entrance guide plate is configured to be swingable, and transfer materials such as plain paper and thin paper and transfer materials such as thick paper and postcards are placed at the nip position between the heating roller and the pressure roller at different guiding angles. Since the causes of troubles during fixing are removed by guiding the fixing device, it is possible to provide a fixing device that can prevent jams, wrinkles of the transfer material, damage to images, etc.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the fixing device of the present invention, FIG. 2 is a perspective view of the vicinity of the entrance guide plate showing an embodiment of the invention, and FIGS. 3a and 3b are side cross-sectional views showing the operation of the entrance guide plate. It is a diagram. 1... Heating roller 2... Pressure roller 3...
Entrance guide plate lO... Swing shaft 11... Entrance guide mounting plate 12... Transmission member 13... Upper limit stopper 1
4...Cam support shaft 15...Cam member 16...
・Cam dial applicant: Konishiroku Photo Industry Co., Ltd.

Claims (1)

[Claims] In a fixing device in which a transfer material on which an unfixed toner image is formed is guided to a pressure contact position between a heating roller and a pressure roller by an entrance guide plate, the fixing device is fixed to the upstream side of the entrance guide plate in the direction in which the transfer material is conveyed. A swinging support shaft, a transmission member fixed to the end of the swinging support shaft and transmitting a swinging motion, and a cam member press-contacting and separating from the transmission member to swing the transmission member, the cam member The fixing device is characterized in that the fixing device is configured to be able to swing the entrance guide plate in the vertical direction about the swing axis as a swing center by operating the inlet guide plate.