JP3072186B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus such as a laser beam printer and an LED printer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser beam printer or an LED printer, an image carrier for carrying a latent image drawn by a laser beam or the like, and a developing device for developing the latent image on the image carrier are developed. The mainstream is provided with a device, a transfer unit for transferring a developed image to a sheet as a transfer material, and a fixing device for fixing the transferred image on the sheet.

Among these, in a fixing device for fixing a transferred image to a sheet, a fixing roller that rotates while being maintained at a predetermined temperature by a heater and a temperature sensor, is brought into contact with the fixing roller at a predetermined pressure, and The mainstream is a method in which a toner serving as a developer is melted by heat and pressure by a rotating pressure roller to fix an image on a sheet.

In this configuration, a guide member (hereinafter, referred to as transfer material guide means) for guiding a sheet conveyed from the transfer device side to a nip between the fixing roller and the pressure roller.
(Referred to as a fixing entrance guide).

FIG. 5 shows an example. A fixing entrance guide 7-5 is fixed to a part b of the fixing frame 7-4 by screwing on the sheet discharge side of the image carrier 5 and the transfer roller 6 as a transfer unit. The fixing frame 7-4 holds the fixing roller 7-1 via a bearing (not shown). Therefore, the sheet P on which the toner image has been transferred by the image carrier 5 and the transfer roller 6 is fixed along the sheet passing surface g of the fixing entrance guide 7-5.
The paper is conveyed toward the nip N of the pressure roller 7-2.

[0006]

However, according to the above-mentioned prior art, the fixing inlet guide 7-5 has a screw or the like at the point b relatively far from the nip between the fixing roller and the pressure roller on the fixing frame 7-4. However, there is a problem as described below.

In the configuration example shown in FIG. 5, the entrance guide 7-5 places importance on the size of the point a which determines the direction of the sheet P coming out of the nip of the image carrier 5 and the transfer roller 6, and the point It is fixed to the fixing frame 7-4 at a relatively close point b according to the seating surface f.

In such a case, even if the entrance guide 7-5 is fixed so as to be in close contact with the seat surface f on the frame side, the leading end d is affected by dimensional tolerance, thermal expansion, bending due to screw fixing, and the like. Accordingly, there has been a problem that the dimensions are likely to be out of order in the direction of the arrow.

The positional deviation of the leading end of the guide fluctuates the conditions under which the paper enters the nip, and is a major cause of wrinkling of the paper and unevenness of the fixing property.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device of an image forming apparatus which can solve the above-mentioned problems and can prevent the occurrence of wrinkles and uneven fixing of a transfer material due to a displacement of a fixing entrance guide. .

[0011]

According to the present invention, an object of the present invention is to provide a pair of fixing members forming a press-contact portion for nipping and conveying a recording material carrying an unfixed image, and a frame supporting the fixing member. in the fixing device having a guide member <br/> for guiding the recording material to the press contact portion, the guide member is fixed to the frame, and an end portion of the press-contact portion side of the guide member through a spring It is achieved by engaging the aforementioned frame Te.

[0012]

In the present invention having such a structure, the guide member is fixed to the frame. In addition to this, in order to more reliably prevent displacement of the end of the guide member on the press contact side. Further, the end of the guide member on the side of the press contact portion is engaged with the frame via a spring . As a result, the conditions under which the recording material enters the press-contact portion of the fixing member are stabilized, and the occurrence of wrinkles and uneven fixing of the recording material is prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings together with reference examples .

< Reference Example> First, a reference example of the present invention will be described with reference to FIGS. Note that the same parts as those of the conventional example shown in FIG. FIG. 1 is a cross-sectional view of a main body of a reference example apparatus applied to a laser beam printer. Reference numeral 1 denotes a paper cassette on which a plurality of sheets P as transfer materials are stacked. The paper P stored in the paper cassette 1 is separated one by one by a paper feed roller 2 and a separation claw 3 at a predetermined timing.
Guided to 4-2.

The sheet P sent out by the timing rollers 4-1 and 4-2 is rotatably mounted on a process cartridge C in which a plurality of process units for forming an image are housed in one housing. It enters between the body 5 and a transfer roller 6 which is a transfer unit arranged to face the image carrier 5. The transfer roller 6 rotates while abutting on the image carrier 5, and
Since a predetermined voltage is applied, the image on the image carrier 5 is transferred onto the paper P while nipping and transporting the paper P at the pressure contact portion between the image carrier 5 and the transfer roller 6. A fixing device 7 is disposed above the image carrier 5 and the transfer roller 6, and the sheet P carrying an unfixed image as described above is integrated with a fixing frame 7-4 of the fixing device 7. Fixing entrance guide 7 which is a transfer material guiding means attached in a fixed manner
The fixing device 7 is guided into the fixing device 7 by -5.

As shown in FIG. 2, the fixing device 7 includes a fixing roller 7-1 made of aluminum and a fixing roller 7 made of aluminum.
And a pressure roller 7-2 made of rubber, which is disposed to face the fixing roller 7-1 by a spring (not shown) so as to be driven and rotatable by a fixed pressure. A heater 7-3 serving as a heating unit is provided inside the fixing roller 7-1.
The temperature of the surface of the fixing roller 7-1 is controlled by controlling the heater 7-3 while detecting the temperature with a temperature sensor (not shown) attached so as to come into contact with the surface. Is maintained at a predetermined temperature. Further, a fixing entrance guide 7-5 for guiding the paper P to the pressure contact portion is provided at a position facing the pressure contact portion between the fixing roller 7-1 and the pressure roller 7-2.

The fixing entrance guide 7-5 is made of a semiconductive mold member having a predetermined electric resistance, and the charge applied to the sheet at the time of transfer is released to the transfer roller 6 side of the guide. Metal elimination core 7-6 is provided and connected to the frame ground.

In the reference device having such a configuration,
As shown in FIG. 3, a hook-shaped position regulating member e that engages with the fixing frame 7-4 is provided at several positions in the longitudinal direction at the tip of the fixing entrance guide 7-5. Thereby, it is possible to prevent the displacement of the fixing entrance guide 7-5, particularly the displacement in the direction indicated by the arrow at the leading end portion d in FIG. 2, without causing the conventional paper wrinkle or fixing unevenness. .

Next, an embodiment of the present invention will be described with reference to FIG. In addition, the same reference numerals are given to the common parts with the reference example, and the description is omitted.

In FIG. 4, a hook portion e 'on the fixing entrance guide 7-5 side and a hook portion h on the fixing frame 7-4 side are provided, and both are engaged by a coil spring i. According to this method, the tensile force of the coil spring i is adjusted in accordance with the amount of thermal expansion at the time of turning on the heater or the amount of bending of the distal end due to screw tightening, and the positional deviation of the distal end can be accurately corrected.

[0021]

As described above, according to the present invention, the guide member is fixed to the frame, and the end of the guide member on the press contact portion side is engaged with the frame.
Although the guide member is fixed to the frame, in addition to this, the end of the guide member on the press contact portion side is provided with a spring in order to more reliably prevent the displacement of the end portion on the press contact portion side of the guide member.
And engaged with the frame via a, thereby entering a condition of the recording material for the contact portion of the fixing member can be stabilized, an effect that the occurrence of wrinkles and uneven fixing of the recording material can be prevented obtain.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a reference example apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a fixing device and a transfer material guiding unit in the apparatus of FIG.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a regulating unit attached to a transfer material guiding unit in the apparatus in FIG. 1;

FIG. 4 is a cross-sectional view illustrating a schematic configuration of an apparatus according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a conventional fixing device and its periphery.

[Explanation of symbols]

 5 Image Carrier 6 Transfer Roller (Transfer Unit) 7 Fixing Device 7-1 Fixing Roller 7-2 Pressure Roller 7-3 Heater (Heating Unit) 7-4 Frame 7-5 Fixing Inlet Guide (Transfer Material Guide Unit) e Position regulating member (position regulating means) P paper (transfer material)

Claims (1)

(57) [Claims] 1. A pair of fixing members that the recording material bearing an unfixed image to form a pressure contact portion for holding and conveying a frame for supporting the fixing member, a guide member for guiding the recording material to the press contact portion The fixing device according to claim 1, wherein the guide member is fixed to the frame, and an end of the guide member on the pressure contact portion side is engaged with the frame via a spring .