JP2006119536A - Cooling mechanism of fixing device in image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to rotationally drive cooling blades 20 by a driving shaft 10 of a heat roller 12 and to rotationally drive the cooling blades 20 only when a paper sheet of a prescribed small size is fixed. <P>SOLUTION: The image forming apparatus is equipped with a paper feed cassette 2 including cursors 6 and 8, and a fixing device 4 including the heat roller 12 integral with the driving shaft 10. Opposite ends of the driving shaft 10 are provided with moving bodies 26 including the cooling blades 20 and control levers 22, and a pair of compression coil springs 28 energizing each of the moving bodies 26. When the cursors 6 and 8 are set at the width of the paper sheet of the prescribed small size and are mounted on the apparatus main part, the respective tips of the cursors 6 and 8 abut on the respective tips of the control levers 22 and move each of the control levers 22. Each of the cooling blades 20 is then more increased in speed than the rotation of the driving shaft 10 and is rotated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a cooling mechanism for a fixing device provided in an image forming apparatus such as an electrostatic copying machine, a laser printer, or a facsimile.

Generally, an image forming apparatus includes a fixing device including a heat roller and a pressure roller pressed against the heat roller. The sheet on which the toner image is transferred is conveyed, and the toner image is fixed while passing between the heat roller and the pressure roller in the fixing device. When small-size paper is continuously fixed, the temperature of both end regions in the axial direction of both rollers, particularly the heat roller, that do not contact the small-size paper may increase excessively. If a large-size sheet is fixed in this state, there is a possibility that defects such as uneven glossiness occur in the image or the rubber layer constituting the heat roller is deformed or deteriorated. In addition, the technical problem is that the fixing device including at least the heat roller, for example, a fixing device including the heat roller and the belt pressed against the heat roller, or the heat roller and the heat roller, other than the above-described form. It also exists in common in a fixing device including a guide member arranged to face a part of the outer peripheral surface with a gap.

In order to solve the above technical problem, for example, by applying the technique disclosed in Patent Document 1, a cooling blade is integrally provided on the drive shaft of the heat roller and rotated together with the drive shaft to cool the heat roller. Can be considered. According to this method, the configuration can be simplified and the heat roller can be cooled at a low cost. However, when the cooling blade is provided integrally with the drive shaft, the cooling blade always rotates when the heat roller is driven to rotate. Therefore, when fixing a paper having a size larger than a small size paper, conversely There is a risk that both ends of the heat roller will be excessively cooled, causing problems such as poor fixing.
JP 2002-278386 A

An object of the present invention is to enable the cooling blade to be rotationally driven by the drive shaft of the heat roller, and to allow the cooling blade to be rotationally driven only when fixing a predetermined small size paper. It is an object of the present invention to provide a cooling mechanism for a fixing device in an image forming apparatus.

According to the present invention,
Cooling of a fixing device in an image forming apparatus including a paper feed cassette that is detachably mounted on the apparatus main body and includes a pair of cursors that regulate the width of the sheet, and a fixing device that includes a heat roller that rotates integrally with the drive shaft. In the mechanism,
At both ends of the drive shaft of the heat roller, an input gear, a cooling blade provided with a driven gear, and an operation lever supported in order from the inside to the outside so as to be movable in the axial direction and relatively rotatable. And a speed-up gear unit meshed with the input gear and the driven gear and disposed so as to be movable in the axial direction together with each of the input gear and the driven gear; A pair of spring members each biasing toward both ends of the shaft;
When the pair of cursors is set to the width of a predetermined small-sized sheet and attached to the apparatus main body, the distal ends of the cursors abut on the distal ends of the operation levers, respectively. Each of the levers is moved from both ends of the drive shaft to the inside in the axial direction against the spring force of the spring member together with the moving body, and the movement causes the input gear of each of the moving bodies to Each of the cooling blades is removably drive-coupled to the drive shaft, and is rotated at a speed higher than the rotation of the drive shaft.
And a fixing device cooling mechanism in the image forming apparatus.
Each of the operation levers extends radially outward from both ends of the drive shaft, and the distal end portions of the operation levers are linearly inclined in directions approaching each other, and the distal end portions The outer inclined surface of each of the cursors is on the movement trajectory in the mounting direction of the paper feed cassette at the tip of each of the cursors set to the width of a predetermined small size paper. In the mounting direction of the paper feed cassette at the tip of each of the cursors positioned on the movement trajectory in the previous movement region positioned at the position and set to the width of the large size paper larger than the predetermined small size It is preferable that the cursor is positioned at an inner position where the tips of the cursors are not in contact with each other.

Embodiments of a cooling mechanism of a fixing device in an image forming apparatus configured according to the present invention will be described below in detail with reference to the accompanying drawings.

Referring to FIGS. 1 to 3, an apparatus main body in an image forming apparatus (not shown) includes a paper feed cassette 2 and a fixing device 4. The paper feed cassette 2 includes a pair of cursors 6 and 8 that are detachably attached to the apparatus main body and regulate the width of the paper (horizontal width orthogonal to the paper feed direction). Each of the cursors 6 and 8 is movably disposed in the paper feed cassette 2 so as to approach and separate from each other in the width direction. The fixing device 4 includes a heat roller 12 disposed so as to be able to rotate integrally with the drive shaft 10 and a pressure roller 14 pressed against the heat roller 12. The drive shaft 10 of the heat roller 12 is rotatably supported by the housing 4H of the fixing device 4 and is drivingly coupled to an electric motor (not shown) disposed in the apparatus main body via a gear (not shown).

While the paper fed from the paper feed cassette 2 passes between the photosensitive drum and the transfer means through a conveyance path disposed in the apparatus main body, a toner image is transferred (all not shown). While the sheet on which the toner image is transferred is further conveyed and passes between the heat roller 12 and the pressure roller 14 in the fixing device 4, the toner image is fixed. The paper on which the toner image has been fixed is discharged onto a paper discharge tray through a conveyance path (both not shown).

Next, the cooling mechanism of the fixing device 4 according to the present invention will be described. The cooling mechanism is movable from the inside (the heat roller 12 side) to the outside at both ends of the drive shaft 10 extending outward from both ends of the heat roller 12 so as to be movable in the axial direction of the drive shaft 10 and relatively rotatable. Is engaged with the cooling blade 20 and the operating lever 22 integrally provided with the input gear 16 and the driven gear 18, and the input gear 18 and the driven gear 18, and is moved in the axial direction together with them. A pair of moving bodies 26 comprising a freely arranged speed increasing gear unit 24; a compression coil spring which is a pair of spring members that urge each of the moving bodies 26 toward both ends of the drive shaft 10; 28 and;

An annular flange 30 having a diameter larger than that of the drive shaft 10 is formed at positions outside the both end surfaces of the heat roller 12 of the drive shaft 10. A compression coil spring 28 is disposed between each of the annular flanges 30 and the corresponding relatively large diameter input gear 16 so as to extend around the drive shaft 10. Spline teeth (male) 32 are formed on the outer peripheral surface of the drive shaft 10 between each of the annular flanges 30 and the corresponding relatively large-diameter input gear 16. Correspondingly, spline teeth (female) (not shown) are formed on the inner peripheral surface of each input gear 16. A driven gear 18 is integrally formed inside each cooling blade 20. An annular flange 33 having a larger diameter than that of the driven gear 18 is integrally formed between each cooling blade 20 and the corresponding driven gear 18. The driven gear 18 has a smaller diameter than the input gear 16.

In the housing 4 </ b> H of the fixing device 4, a fixed shaft 34 is disposed so as to extend parallel to the drive shaft 10 and the heat roller 12 at a distance. Each of the speed increasing gear units 24 includes a speed increasing small diameter gear 36 having a much smaller diameter than the input gear 16 and a speed increasing large diameter gear 38 formed integrally with the speed increasing small diameter gear 36. The speed increasing large diameter gear 38 has substantially the same diameter as the input gear 16. The speed increasing small diameter gear 36 is disposed on the inner side in the axial direction with respect to the speed increasing large diameter gear gear 38 and is meshed with the input gear 16. The speed increasing large diameter gear 38 is meshed with the driven gear 18. Each of the speed increasing gear units 24 is supported at both ends of the fixed shaft 34 so as to be movable in the axial direction and relatively rotatable. The speed-up large-diameter gear 38 in each speed-up gear unit 24 is disposed with a slight axial gap between the corresponding input gear 16 and the annular flange 33 of the cooling blade 20. With this configuration, each of the moving bodies 26 is integrally urged toward the both ends of the drive shaft 10 by the corresponding compression coil springs 28.

Retaining rings (not shown) are provided at both ends of the drive shaft 10 to prevent the corresponding moving body 26 from coming off. Each of the moving bodies 26 is pressed against the retaining ring via the operation lever 22 by a corresponding compression coil spring 28. In this state, the spline teeth (not shown) of each of the input gears 16 are positioned on the outer side in the axial direction of the corresponding spline teeth 32 formed on the outer peripheral surface of the drive shaft 10 and are not meshed with the spline teeth 32. . Therefore, even if the drive shaft 10 is rotationally driven by an electric motor (not shown), the rotational driving force is not transmitted to each of the input gears 16, so that each of the cooling blades 20 is stopped (FIGS. 2 and 3). In the state shown in FIG.

Each of the operation levers 22 extends radially outward from both ends of the drive shaft 10, and the distal end portion 23 of each of the operation levers 22 is inclined almost horizontally and linearly in a direction approaching each other. . Each outer inclined surface 23a of the front end portion 23 of each of the operation levers 22 has a width of a predetermined small size paper (for example, the length of the A4 size paper when the longitudinal direction is set in the paper feeding direction. The movement in the moving region of the front end of each of the cursors 6 and 8 set at the horizontal interval) on the movement trajectory in the mounting direction of the paper feed cassette 2 and before the paper feed cassette 2 is positioned at the mounting position. It is positioned on the trajectory. The outer inclined surface 23a of each of the front end portions 23 of each of the operation levers 22 also has a width of a large size paper larger than a predetermined small size (for example, the width direction of A4 size paper is directed to the paper feeding direction. The tip of each of the cursors 6 and 8 set at the horizontal interval of the paper when the paper is set is moved against the movement trajectory of the paper feed cassette 2 in the mounting direction. It is positioned at the inner position where it is not touched. Note that the lower surface of each partial region of the operation lever 22 is placed on a receiving surface (not shown) disposed at a corresponding position of the apparatus main body, and the rotation due to its own weight is prevented. Retained.

When the pair of cursors 6 and 8 are set to a predetermined small-size sheet width and mounted on the apparatus main body (not to mention that sheets are stacked between the cursors 6 and 8), the cursor 6 8 and 8 are in contact with the outer inclined surfaces 23a of the respective distal end portions 23 of the operation levers 22, and each of the operation levers 22 is moved from both ends of the drive shaft 10 to the inner side in the axial direction. 26 is moved against the spring force of the compression coil spring 28. By this movement, the spline teeth of each input gear 16 of the moving body 26 are detachably drive-coupled to the spline teeth 32 of the drive shaft 10. When the drive shaft 10 of the heat roller 12 is driven to rotate by an electric motor (not shown), the rotation of the drive shaft 10 is cooled through each of the input gear 16, each of the speed increasing gear unit 24, and each of the driven gears 18. Each of the cooling blades 20 is transmitted at a speed higher than that of the drive shaft 10 and is rotated. With each rotation of the cooling blade 20, cooling air is blown from the outside of the apparatus main body toward both ends of the heat roller 12 and the pressure roller 14, and both ends of the heat roller 12 and the pressure roller 14 are effectively cooled. The As a result, even when a predetermined small size paper is continuously fixed, the temperature of the both end regions in the axial direction of the heat roller 12 and the pressure roller 14 that do not contact the small size paper, particularly the heat roller 12, is high. An excessive rise is reliably prevented.

When the paper feed cassette 2 is detached from the apparatus main body, the distal ends of the cursors 6 and 8 are separated from the outer inclined surfaces 23a of the distal end portions 23 of the operation levers 22, respectively. Then, the actuator is moved toward both ends of the drive shaft 10 by the spring force of the corresponding compression coil spring 28. By this movement, the spline teeth of each input gear 16 of the moving body 26 are disengaged from the spline teeth 32 of the drive shaft 10 and the mutual drive coupling is released. Subsequently, when the paper feed cassette 2 in which each of the cursors 6 and 8 is set to a width of a large size paper larger than a predetermined small size is attached to the apparatus main body and fixing is performed on the large size paper, Since the temperatures of the heat roller 12 and the pressure roller 14, particularly the axial end regions of the heat roller 12, do not increase excessively, gloss unevenness occurs in the image, or the rubber layer constituting the heat roller 12 is deformed or deteriorated. The possibility of malfunctions such as being avoided is certainly avoided. In addition, since each of the cooling blades 20 is stopped in spite of the rotation of the drive shaft 10 of the heat roller 12, the heat roller 12 and the pressure roller 14, particularly the axial end regions of the heat roller 12 are excessive. The cooling is avoided.

Thus, according to the present invention, the cooling blade 20 can be rotationally driven by the drive shaft 10 of the heat roller 12, and the cooling blade 20 is rotationally driven only when fixing a predetermined small size paper. Make it possible. Further, although the cooling blade 20 is rotationally driven by the drive shaft 10 of the heat roller 12, the rotation of the cooling blade 20 can be increased more than the rotation of the drive shaft 10, so that both end portions of the heat roller 12 and the pressure roller 14 are provided. Can be effectively cooled. Further, it is not necessary to provide a special electric motor for rotating the cooling blade 20, and it is not necessary to perform control according to the size of the paper, and the width of the cursors 6 and 8 of the paper feed cassette 2 is reduced. Since the cooling blades 20 can be rotated and linked, the configuration is simple and both ends of the heat roller 12 and the pressure roller 14 can be cooled at low cost. The present invention is not limited to the fixing device 4 including the heat roller 12 and the pressure roller 14 in pressure contact with the heat roller 12 as shown in the above embodiment. A fixing device including at least the heat roller 12, for example, a fixing device including the heat roller 12 and a belt pressed against the heat roller 12, or a gap in a part of the outer peripheral surface of the heat roller 12 and the heat roller 12. The present invention can also be applied to a fixing device including a guide member disposed so as to face each other.

1 is an exploded perspective view showing an embodiment of a cooling mechanism of a fixing device in an image forming apparatus configured according to the present invention. It is a perspective view which shows a part of cooling mechanism shown in FIG. It is the perspective view which expanded and looked at a part of FIG.

Explanation of symbols

2: Feed cassette 4: Fixing device 6, 8: Cursor 10: Drive shaft 12: Heat roller 14: Pressure roller 16: Input gear 18: Driven gear 20: Cooling blade 22: Control lever 23: Tip 23a: Outside Inclined surface 24: speed increasing gear unit 26: moving body 28: compression coil spring 30, 33: annular flange 32: spline tooth 34: fixed shaft 36: speed increasing small diameter gear 38: speed increasing large diameter gear

Claims (2)

Cooling of a fixing device in an image forming apparatus including a paper feed cassette that is detachably mounted on the apparatus main body and includes a pair of cursors that regulate the width of the sheet, and a fixing device that includes a heat roller that rotates integrally with the drive shaft. In the mechanism,
At both ends of the drive shaft of the heat roller, an input gear, a cooling blade provided with a driven gear, and an operation lever supported in order from the inside to the outside so as to be movable in the axial direction and relatively rotatable. And a speed-up gear unit meshed with the input gear and the driven gear and disposed so as to be movable in the axial direction together with each of the input gear and the driven gear; A pair of spring members each biasing toward both ends of the shaft;
When the pair of cursors is set to the width of a predetermined small-sized sheet and attached to the apparatus main body, the distal ends of the cursors abut on the distal ends of the operation levers, respectively. Each of the levers is moved from both ends of the drive shaft to the inside in the axial direction against the spring force of the spring member together with the moving body, and the movement causes the input gear of each of the moving bodies to Each of the cooling blades is removably drive-coupled to the drive shaft, and is rotated at a speed higher than the rotation of the drive shaft.
A cooling mechanism for a fixing device in an image forming apparatus. Each of the operation levers extends radially outward from both ends of the drive shaft, and the distal end portions of the operation levers are linearly inclined in directions approaching each other, and the distal end portions The outer inclined surface of each of the cursors is on the movement trajectory in the mounting direction of the paper feed cassette at the tip of each of the cursors set to the width of a predetermined small size paper. In the mounting direction of the paper feed cassette at the tip of each of the cursors positioned on the movement trajectory in the moving area in front of the position and set to the width of the large size paper larger than the predetermined small size 2. The fixing device cooling mechanism in the image forming apparatus according to claim 1, wherein each of the cursors is positioned at an inner position where the tips of the cursors are not in contact with each other.

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