JPH0529063U - Heat fixing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a heat fixing device capable of saving power, simplifying the configuration, and downsizing. [Structure] Support member 32 integrated with PTC heating element 31
Is fixedly supported by the frame, and a semi-cylindrical guide member 36 is slidably fitted in the support member 32 in the arrow E direction. The rotation shaft 37 is penetrated through the center of the guide member 36,
The sprocket members 41 and 42 are fixed to the guide members 36 at both ends. The guide member 36 and the support member 32 are surrounded by the belt-shaped thin film 43,
The thin film 43 is hooked on the sprocket members 41 and 42. The guide member 36 is connected to the spring 40 via the rotary shaft 37.
The thin film 43 is maintained in a predetermined tension by being urged in the direction away from the support member 32 by a and 40b. When the pressure roller is pressed against the PTC heating element 31 via the thin film 43 and the sheet is conveyed by driving the thin film 43 between them, the toner image is fixed on the sheet.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat fixing device which is incorporated in an image forming apparatus such as a printer device, a copying machine, a facsimile device and the like that employs an electrophotographic method, and fixes a toner image on a sheet by thermocompression bonding.

[0002]

[Prior Art]

 Conventionally, as a heat fixing device incorporated in an image forming apparatus, a device as shown in FIG. 6 has been proposed. This heating and fixing device uses a sheet heating heater with a small heat capacity and a thin film as a heating element instead of the heating rolls that have been used so far, thus greatly reducing the heat-up time and saving power. It was made feasible.

In FIG. 6, the sheet heating heater 2 is embedded in a heating element body 3, the whole is fixed to a supporting member 4, and a thermistor 5 for detecting the temperature of the sheet heating heater 2 is provided. The whole of these constitutes the heating unit 1. Further, a drive shaft 6 and a tension shaft 7 are provided separately from the heating unit 1 and at a predetermined distance from the heating unit 1, and a belt-shaped thin film 8 is stretched so as to surround them. The film 8 is driven by the drive shaft 6 in the directions of arrows A ₁ , A ₂ and A ₃ , and the tension thereof can be adjusted by the tension shaft 7. Further, a pressure roll 9 is arranged in pressure contact with the sheet heater 2 via a thin film 8, and the pressure roll 9 is driven by the thin film 8 driven by the drive shaft 6 to rotate in the direction of arrow B. It is possible. In the heat fixing device having the above structure, the paper P is conveyed on the paper P by the thin film 8 moving at a constant speed between the sheet-like heat generating heater 2 kept at a predetermined temperature and the pressure bonding roll 9. The toner image T carried on the sheet P is fixed on the sheet P.

In the above example, the temperature control of the heater 2 is based on the temperature detection by the thermistor 5. However, in contrast to this, the heater itself has a positive temperature coefficient heating element (hereinafter, PTC heating element). It is also proposed that the self-temperature control can be performed by using When a constant voltage is applied to the PTC heating element, a current flows according to the initial resistance, the temperature starts to rise due to self-heating, and the resistance value rapidly increases when reaching a certain constant temperature (switching temperature). The current decreases and becomes constant, and the temperature is kept constant (self-temperature control function). By using such a function as a constant temperature heating element, the current can be turned on and off by a thermistor. It has been used in various fields as a heater that does not require control.

[0005]

[Problems of conventional technology]

 In the conventional heat fixing device shown in FIG. 6, the drive shaft 6 for driving the belt-shaped thin film 8 and the tension shaft 7 are separately provided at a predetermined distance from each other. Can not be used in. Further, the belt-shaped thin film 8 is likely to be biased as it is driven, and in order to prevent this, it is necessary to separately provide a belt biasing prevention mechanism. For this reason, although power saving can be achieved, there is a problem that the structure becomes very complicated and the device becomes large.

[0006]

[The purpose of the device]

 SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a heating and fixing device that enables power saving as well as simplification and size reduction of the configuration.

[0007]

[Key points of the device]

 In order to achieve the above object, the present invention comprises a heating member having a heat source, and a pressure contact member that is in pressure contact with the heating member, and conveys a paper carrying a toner image between the heating member and the pressure contact member. In a heat fixing device for fixing a toner image to the sheet, the heating member is integrally provided with the heat source, and is provided with a support member which is orthogonal to the sheet conveying direction and extends along the sheet surface and is fixedly supported, and a peripheral member. It is formed in a semi-cylindrical shape with an opening formed by cutting out a part of the surface, and the opening is engaged with the supporting member so as to face the supporting member and slides in a direction orthogonal to the paper surface. A semi-cylindrical guide member that is movable, a rotation shaft that penetrates the semi-cylindrical guide member through the center of the circle, and a semi-cylindrical guide member that is fixed to both ends of the rotation shaft on the rotation shaft. -Shaped sprocket members with the same diameter as the guide member, An endless thin film member that surrounds the semi-cylindrical guide member and the support member and is hooked to the two sprockets, and a direction in which the semi-cylindrical guide member is separated from the support member via the rotation shaft. An urging member for urging and a drive transmission member for rotationally driving the rotating shaft are provided.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 is an overall configuration diagram of an image forming apparatus (here, a printer device is shown as an example) in which a heat fixing device according to an embodiment of the present invention is incorporated. The image forming apparatus shown in the figure has a paper feed cassette 11 for stacking and storing papers P, a paper feed roll 12 for sequentially feeding the papers P one by one from the topmost paper, and a predetermined waiting time for the fed papers. A standby roll 13 for re-feeding at a timing is provided, and a photoconductor drum 14, a charger 15, and an image forming unit for forming a toner image on the paper P conveyed from the standby roll 13 by electrophotography. A print head 16, a developing device 17, a transfer device 18, a cleaner 19 and the like are provided. Further, the heating and fixing device 20 of the present embodiment for fixing the toner image formed on the paper carrying the toner image formed by the image forming section, the transport roller 21, the paper discharge roll 22, the paper discharge tray 23, etc. It is configured to include. The structure of the heat fixing device 20 will be specifically described below.

FIG. 1 is an exploded perspective view of a heating member side of the heat fixing device 20 of this embodiment, and FIG. 2 is a vertical sectional view taken along the rotational axis direction of the heat fixing device 20, and FIG. , (B) are AA sectional views and BB sectional views in FIG. 2, respectively.

As shown in these figures, a rod-shaped PTC heating element 31 processed to have a cross-sectional shape such that one side of a quadrangle has a curvature is provided as a heat source, and the PTC heating element 31 has a curved surface portion. It is embedded and integrated in a support member 32 larger than the PTC heating element 31 so that only 31a is exposed on the surface. The support member 32 is made of a material such as ceramic having heat resistance and insulation properties, and extends along the surface of the sheet to be conveyed (the arrow C direction in FIG. 3A) and the direction orthogonal to the sheet conveyance direction (the arrow C direction). It is extended in the D direction), and both ends 32a and 32b thereof are fixedly supported by a frame 33 outside the apparatus as shown in FIG. Further, as shown in FIG. 1, a groove 32c is formed in the support member 32 along the direction of the arrow D as a space for avoiding a rotary shaft 37 described later, and both end portions 32a and 32b of the support member 32 are also formed. The sprocket members 41 and 42, which will be described later, are formed with a certain level difference from the central portion so as to avoid them. Further, as shown in FIG. 2, leads 34a and 34b connected to both ends of the PTC heating element 31 are embedded in both ends 32a and 32b of the support member 32, and the leads 34a and 34b are connected to the connectors 34a and 34b, respectively. A predetermined voltage is applied from outside the device via 35a and 35b.

Further, as shown in FIG. 1, a semi-cylindrical guide member 36 having an opening 36a formed by cutting out a part of the peripheral surface is slid in a direction (arrow E direction) orthogonal to the sheet surface to be conveyed. The opening 36a is fitted to the supporting member 32 so as to be movable, as shown in FIG. At the center of such a semi-cylindrical guide member 36, a rotary shaft 37 that is movable in the arrow E direction with respect to the frame 33 is provided so as to penetrate therethrough. As shown in FIG. 2, the rotary shaft 37 is rotationally driven by a drive source (not shown) provided outside the apparatus via a drive gear 38 as a drive transmission member, and bearings 39a and 39b at both ends are rotated. Via the springs 40a and 40b as biasing members, the guide member 36 is biased in the direction away from the support member 32 along the arrow E direction.

Further, cylindrical bases 41a and 42a having the same diameter as the guide member 36 are provided at positions on the rotary shaft 37 at both ends of the guide member 36, and convex shapes provided at regular intervals on the peripheral surface thereof. The sprocket members 41 and 42 including the portions 41b and 42b are fixed to each other. Then, the semi-cylindrical guide member 36 and the supporting member 32 are made of a material having heat resistance and toner releasability (for example, the surface of a polyimide film having heat resistance is coated with Teflon to impart the toner releasability). It is surrounded by a belt-shaped thin film 43 which is an endless thin film member made of a material such as the above. The thin film 43 has a width sufficient to reach from the one sprocket member 41 to the other sprocket member 42 via the guide member 36, and the sprocket members 41, 42 are provided in holes 43a provided at both ends thereof at regular intervals. One in which the convex portions 41b, 42b of FIG. 3 are engaged as shown in FIG. 3 (b), and the rotating shaft 37 and the guide member 36 are separated from the support member 32 by the urging force of the springs 40a, 40b as described above. By being biased in the direction, the entire thin film 43 is maintained in a predetermined tension. When the rotating shaft 37 is rotationally driven in this state, the driving force is transmitted to the thin film 43 through the sprocket members 41 and 42, so that the thin film 43 has a predetermined tension as shown in FIG. It is driven in the direction of arrow F while maintaining it.

On the other hand, as a press-contact member that press-contacts the heating member having the above-described configuration, a pressure roll 44 as shown in FIGS. 2 and 3A is provided. The pressure-bonding roll 44 has a structure similar to that of a normal pressure-bonding roll that has been conventionally used. Both ends of the pressure-bonding roll 44 are supported by bearings 45a and 45b so as to be movable in the arrow E direction. The entire pressing roll 44 is pressed against the PTC heating element 31 through the thin film 43 at a predetermined pressure by the urging force, and is driven by the thin film 43 to rotate in the direction of arrow G as shown in FIG. 3 (a). To do.

In the heat fixing device 20 of the present embodiment having the above-described configuration, the main power source of the image forming apparatus shown in FIG. 4 is turned on to lead the PTC heating element 31 from the power source portion (not shown). A predetermined voltage is applied via 34a and 34b, whereby the PTC heating element 31 rises to a predetermined temperature (fixable temperature) with almost no waiting time, and a constant temperature is maintained by the self-temperature control function described above. .. When the print start switch is turned on in this state, the paper feeding by the paper feeding roll 12 is started and the driving force from the driving source (not shown) in the image forming apparatus is rotated via the driving gear 38 (FIG. 2). It is transmitted to the shaft 37, which drives the thin film 43 via the sprocket members 41 and 42. Then, the sheet conveyed while carrying the unfixed toner image from the sheet feeding section through the image forming section passes between the PTC heat generating element 31 and the pressure bonding roll 44 according to the movement of the thin film film 43. Thermocompression is applied to fix the toner image on the paper.

Therefore, according to the present embodiment, according to the present embodiment, the conventional PTC heating element or the planar heating heater has a large and complicated structure as shown in FIG. Since the heating member side has a compact structure that can be handled in the same manner as a conventional single heating roll, simplification and downsizing of the entire fixing device can be realized. Moreover, since a PTC heating element having a very short heat-up time and a self-temperature control function is used as a heat source for the heating member, power saving can be achieved and a current control means such as a thermistor is not required. It is possible to further simplify the configuration.

The PTC heating element 31 has a cross-sectional shape such that one side of a quadrangle has a curvature as shown in FIG. 3A, or a cylindrical shape as shown in FIG. 5, for example. The thing of can also be used conveniently. In short, it is ideal that a part of the cross-sectional shape of the PTC heating element has a curvature, and this curvature is utilized and the shape of the support member 32 is formed so as to match the curvature of the sprocket members 41 and 42. Although it is a shape, it is not limited to a shape having such a curvature, and a flat surface or a rectangular shape can also be adopted.

Further, in the present invention, as the heat source of the heating member, various types can be adopted in addition to the PTC heat generator having the self-temperature control function, as long as it enables power saving. It is also possible to use the sheet heating heater as shown in 6 with a thyristor.

[0018]

[Effect of the device]

 According to the present invention, the structure on the heating member side is devised so that the structure is compact enough to be handled like a conventional heating roll, thereby reducing power consumption and improving the structure of the entire fixing device. Realization of simplification and miniaturization.

Furthermore, if a PTC heating element having a self-temperature control function is used as the heat source of the heating member, it is not necessary to add temperature control means using a thyristor or the like, and the configuration can be further simplified. ..

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a heating member side of a heat fixing device according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along the rotational axis direction of the heat fixing device of the embodiment.

3A and 3B are cross-sectional views taken along a direction orthogonal to the rotation axis direction of the heat fixing device of the embodiment, and FIGS. 3A and 3B are cross-sectional views taken along line AA and B- in FIG. 2, respectively. It is a B sectional view.

FIG. 4 is an overall configuration diagram of an image forming apparatus incorporating the heat fixing device of the embodiment.

FIG. 5 is a cross-sectional view of a heat fixing device according to another embodiment of the present invention taken along a direction orthogonal to the rotation axis direction.

FIG. 6 is a schematic configuration diagram of a conventional heat fixing device using a sheet heater.

[Explanation of symbols]

 20 heat fixing device 31 PTC heating element 32 support member 36 guide member 37 rotating shaft 38 drive gears 40a, 40b springs 41, 42 sprocket member 43 thin film 44 pressure bonding roll

Claims (2)

[Scope of utility model registration request] 1. A heating member having a heat source, and a pressure contact member that is in pressure contact with the heating member, wherein a sheet carrying a toner image is conveyed between the heating member and the pressure contact member to fix the toner image on the sheet. In the heat fixing device, the heating member is provided integrally with the heat source, is provided with a support member that is orthogonal to the paper conveyance direction and extends along the paper surface and is fixedly supported, and a part of the peripheral surface is cut away. A semi-cylindrical guide member which is formed in a semi-cylindrical shape and has an opening which is engaged with the support member so as to face the support member and is slidable in a direction orthogonal to the paper surface. A rotary shaft that penetrates the semi-cylindrical guide member at the center of the circle, and two fixed shafts that are fixed to both ends of the semi-cylindrical guide member and have the same diameter as the semi-cylindrical guide member. A sprocket member, and the semi-cylindrical guide member Serial support member surrounds the 2
An endless thin film member hooked on one sprocket member, an urging member for urging the semi-cylindrical guide member in a direction away from the supporting member via the rotation shaft, and a drive transmission for rotationally driving the rotation shaft. A heat fixing device comprising: a member. 2. The heat fixing device according to claim 1, wherein the heat source is a positive temperature coefficient heating element having a self-temperature control function.