JP2004061718A - Fixing device for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device of a fixing belt system for an image forming apparatus, which has high heat efficiency, excellent safety, short rise-time, and is small and low cost. <P>SOLUTION: The fixing device 10 comprises: a heat plate 11; a hold member 14 which holds the heat plate 11 with a space from the heat plate 11; a pressure pad 15 disposed opposite the heat plate 11 with a space from the hold member 14; a fixing belt 16 wound round the heat plate 11 and a pressure pad 15; and a pressure roller 17 disposed opposite the pressure pad 15 via the fixing belt 16. The hold member 14 is formed from holding bodies having semicylindrical receiving portions, and a holding plate. The heat plate 11 is fixed in such a manner that the semicylindrical receiving portions of the holding bodies are fitted on the longitudinal both ends of a plate substrate 11a. The heating element 13 on the internal face of the heat plate 11 is covered, with a space from the hold member 14. Accordingly, heat dissipation is curbed. Thus, heat efficiency is high and safety is excellent. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device for an image forming apparatus such as an electrophotographic copying machine or a printer.
[0002]
[Prior art]
2. Description of the Related Art In a conventional electrophotographic image forming apparatus such as a copying machine or a printer, a photoconductor is uniformly charged, and an image is exposed thereon to form an image latent image. Then, the formed image latent image is developed with toner to form a toner image of the image, which is transferred to a recording medium or transferred to an intermediate transfer member and further transferred to a recording medium, and the transferred toner image is transferred. An image is formed by performing a heat fixing process by a fixing device.
[0003]
The fixing device includes a fixing roller type fixing device and a fixing belt type fixing device. In a fixing roller type fixing device, a heating roller having a heat source therein and a pressure roller are disposed in contact with each other so as to face each other, and a recording in which a toner image is transferred to a fixing nip portion between the heating roller and the pressure roller. A configuration is provided in which the toner image is heated and pressurized by passing through a medium to perform a fixing process.
[0004]
The fixing belt-type fixing device has a fixing belt provided between a heating roller having a heat source therein and a winding roller, and transmits heat of the heating roller to the fixing belt to heat the fixing belt, thereby winding the fixing belt. A fixing device is provided in which a recording medium on which a toner image is transferred passes through a fixing nip portion between a pressure roller and a fixing belt disposed opposite to the roller, and the toner image is heated and pressed to perform a fixing process.
[0005]
In addition, in the fixing device of the fixing belt type, the heating roller is replaced with a semi-cylindrical heating member that does not rotate, that is, a gutter-like heating member, and a fixing belt is provided between the semi-cylindrical heating member and the winding roller. A configuration has been proposed (see JP-A-2001-343849). In this configuration, since the heating roller is replaced with a semi-cylindrical heating member that does not rotate, the diameter of the heating roller is substantially reduced to half, so that the lateral dimension of the fixing device can be reduced, and the device can be easily downsized. In addition, since a sheet-like heating element can be directly attached to the inner surface of the gutter-like heating member as a heat source, there is an advantage that heat transfer efficiency is high and a standby time can be reduced.
[0006]
[Problems to be solved by the invention]
However, in the fixing device of the fixing belt type using the above-described semi-cylindrical heating member, since the inner surface of the semi-cylindrical heating member is opened, heat is wastedly radiated to lower the thermal efficiency, and the safety is reduced. It was not enough in terms of sex, and there was a risk of accidentally getting burned when checking the equipment. An object of the present invention is to solve the above problems.
[0007]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and the invention according to claim 1 includes a heating plate, a loop-shaped fixing rotator wound around the heating plate and a support member and held rotatably, A pressure rotator pressed against the support member via the fixing rotator, and a fixing process is performed by passing a recording medium on which a toner image is formed between the fixing rotator and the pressure rotator. In the fixing device of the image forming apparatus, the heating plate has a semi-cylindrical plate substrate made of at least a heat conductive material, and a surface of the plate substrate opposite to a surface in contact with the fixing rotating body. And a heating member arranged in a semi-cylindrical shape, the heating plate being held by a holding member arranged so as to cover the heating element at a distance from the heating element. Features A fixing device of an image forming apparatus.
[0008]
The holder may hold the heating plate at one or both ends of the semi-cylindrical heating plate in a circumferential direction and a cylindrical axis direction.
[0009]
Further, it is preferable that the holding body is arranged on the heating plate side of the heating plate, and holds the heating plate at least at a circumferential end and a central portion of the heating plate.
[0010]
Further, a temperature detecting element for detecting a temperature of the heating element is arranged on the holding body so as to contact the heating element.
[0011]
In the heating plate, an electric insulating layer may be disposed between the plate substrate and the heating element, and the electric insulating layer may extend at least a predetermined dimension outside the end of the heating element.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a cross-sectional view illustrating a configuration of a fixing device 10 according to an embodiment of the present invention. The fixing device 10 has a holding plate that holds a heating plate with a space between the heating plate 11 and the heating plate 11. The holding member 14 which is a body, the pressing pad 15 which is a supporting member disposed on the opposite side of the heating plate 11 with the holding member 14 interposed therebetween, and the fixing wound around the heating plate 11 and the pressing pad 15 so as to be erected. The image forming apparatus includes a fixing belt 16 as a rotating body, and a pressing roller 17 as a pressing rotating body disposed at a position facing the pressing pad 15 with the fixing belt 16 interposed therebetween.
[0013]
As shown in FIG. 2, an opposing roller 18 as a support member is disposed in place of the pressure pad 15 as a support member, and the fixing belt 16 is wound around the heating plate 11 and the opposing roller 18 to be installed. The pressure roller 17 may be arranged at a position facing the opposing roller 18 with the fixing belt 16 interposed therebetween.
[0014]
The heating plate 11 is formed on a plate substrate 11 a formed of a heat conductive material, for example, a metal plate such as copper or aluminum and having a thickness of about 0.5 mm in a semi-cylindrical shape (gutter shape) via an electric insulating layer 12. The heating element 13 is adhered and attached by other appropriate means. The electric insulating layer 12 extends outward from the peripheral end of the heating element 13 by a predetermined dimension, for example, 2.0 mm or more when the power supply voltage is 100 V to 125 V, and 2.5 mm or more when the power supply voltage is 200 V to 240 V. In addition, the peripheral end of the heating element 13 and the plate substrate 11a are configured so as not to be short-circuited.
[0015]
The electric insulating layer 12 uses a heat-resistant synthetic resin film, and for example, a polyimide film having a thickness of about 10 to 30 μm may be used.
[0016]
The heating element 13 is a resistor in which metal powder is dispersed in a heat-resistant synthetic resin, for example, a resistor in which nichrome powder, molybdenum powder, or the like is dispersed in polyimide (PI), or a resistor in a metal foil, for example, about 20 to 30 μm. Stainless steel foil, and other metal foil resistors can be used. Although not shown in FIG. 1, the heating element 13 is provided with a power supply terminal, and a temperature detecting element for detecting the temperature of the heating element 13 is disposed in contact therewith. Power is supplied through a control device, and temperature control is performed so as to maintain a predetermined fixing temperature.
[0017]
Since there are a plurality of embodiments of the holding member 14 for holding the heating plate 11, the configuration will be described later in detail. The holding member 14 is formed by molding a synthetic resin. Examples of the synthetic resin material include polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), acrylonitrile butadiene styrene (ABS), or polybutylene terephthalate (PBT) and acrylonitrile butadiene styrene (ABS). Although a synthetic resin such as a mixture, polyamide imide (PAI), or polyimide (PI) is used, a fiber reinforced composite material obtained by mixing 50% or less of glass fiber in these resin materials may be used.
[0018]
The pressure pad 15 is made of a material having high heat resistance and low thermal conductivity, such as a silicon sponge having a PFA layer coated on its surface, and the pad body is coated with a material having low frictional resistance. You. The pressure pad 15 may be fixed to a fixing device after being attached to an appropriate holding member.
[0019]
The fixing belt 16 is a loop-shaped endless belt that is wound around the heating plate 11 and the pressure pad 15 and is erected. As the fixing belt 16, a belt formed by coating a silicon rubber layer on a nickel thin plate, a belt formed by coating a PFA layer on a polyimide resin thin plate, or the like is used.
[0020]
The pressure roller 17 and the opposing roller 18 are, for example, a silicon sponge covered on an aluminum or iron core, a surface of which is covered with a PFA layer, or an aluminum or iron core covered with silicon rubber. It is made of a material having high heat resistance, such as a material whose surface is covered with a PFA layer.
[0021]
Here, the fixing operation by the fixing device 10 will be briefly described. The heating plate 11 is energized to the heating element 13 under the control of a control device (not shown), and is heated to a predetermined fixing temperature. The pressure roller 17 rotates in the direction of arrow a, and the fixing belt 16 driven by being pressed against the pressure roller 17 also moves in the direction of arrow b. Heat is transmitted from the heating plate 11 while the fixing belt 16 moves while rubbing and contacting the non-rotating heating plate 11, and is heated to a predetermined fixing temperature.
[0022]
A recording medium P on which a toner image is formed is conveyed from an image forming mechanism of an image forming apparatus (not shown). When the recording medium P is passed through a fixing nip portion N which is a pressure contact portion between the pressure roller 17 and the fixing belt 16, the toner image on the recording medium P comes into contact with the fixing belt 16 heated to a predetermined fixing temperature. While being heated, pressure is applied by the pressure roller 17 to complete the fixing process of the toner image on the recording medium P.
[0023]
Next, a holding structure of the heating plate 11 by the holding member 14 will be described. The holding member 14 holds the heating plate at a distance from the heating plate 11, and there are a plurality of embodiments of the holding structure.
[0024]
FIGS. 3A and 3B are views showing a first embodiment of a holding structure for fixing the heating plate 11 to the holding member 14, wherein FIG. 3A is a perspective view showing the appearance thereof, and FIG. FIG.
[0025]
The holding member 14 includes holding bodies 14a and 14b each having an end surface formed in a semi-cylindrical receiving portion, and a holding plate 14c. The semi-cylindrical receiving portions of the holders 14a and 14b are fitted to both ends in the longitudinal direction (axial direction of the semi-cylindrical shape) of the plate substrate 11a, and the holders 14a and 14b are screwed to the holding plate 14c with screws 14d and 14e. Fix with. 14f denotes a mounting hole provided in the holding body, and 14h and 14g denote screw holes provided in the holding plate 14c.
[0026]
According to the above configuration, the semi-cylindrical heating plate 11 has a circumferential end that contacts the holding plate 14c and a cylindrical end that has the semi-cylindrical receiving ends of the holders 14a and 14b. Only by contacting the heating element 11, a space is formed between the heating element 13 disposed on the inner surface of the heating plate 11 and the holding bodies 14a and 14b and the holding plate 14c. Is held to cover.
[0027]
Thereby, since the inner surface of the heating plate 11 is closed, radiation of heat is suppressed, so that thermal efficiency can be improved and safety can be improved.
[0028]
FIG. 4 is a sectional view showing a second embodiment of the holding structure for fixing the heating plate 11 to the holding member 14.
[0029]
The plate substrate 11a of the heating plate 11 is formed such that an upper end and a lower end in a circumferential direction are bent in a semi-cylindrical radial direction to form an extension 11a1 and an extension 11a2, and an extension 11a1 and an extension 11a2. Is fixed to the side surface of the holding plate 14c. Both ends in the longitudinal direction (semi-cylindrical axial direction) of the heating plate 11 may be closed by appropriate means such as providing a closing plate on the holding plate 14c for safety. As the closing configuration, for example, the same configuration as that of the first embodiment shown in FIG. 3 can be adopted.
[0030]
Also according to this configuration, the semi-cylindrical heating plate 11 is configured such that the circumferential end of the heating plate 11 only contacts the holding plate 14c, and the heating element 13 disposed on the inner surface of the heating plate 11 and the holding plate 14c A space is formed, and the heating element 13 is held so as to cover the holding member 14 at a distance from the holding member 14, so that the radiation of heat is suppressed and the heat efficiency is increased, and the safety can be enhanced.
[0031]
FIG. 5 is a sectional view showing a third embodiment of the holding structure for fixing the heating plate 11 to the holding member 14.
[0032]
The plate substrate 11a of the heating plate 11 has a semi-cylindrical radially bent extension 11a1 at an upstream end and a downstream end in the moving direction of the fixing belt 16 wound thereon. An extension 11a2 is formed, and the extension 11a1 and the extension 11a2 are fitted and fixed in grooves 14c1 and 14c2 provided on the upper and lower end surfaces of the holding plate 14c. In this configuration, the plate substrate 11a can be slid and fitted to the holding plate 14c to the near side or the far side in FIG. 5, thereby facilitating the mounting operation.
[0033]
Both ends in the longitudinal direction (semi-cylindrical axial direction) of the heating plate 11 may be closed by appropriate means such as providing a closing plate on the holding plate 14c for safety. As the closing configuration, for example, the same configuration as that of the first embodiment shown in FIG. 3 can be adopted.
[0034]
Even with this configuration, the semi-cylindrical heating plate 11 is configured such that the circumferential end thereof only comes into contact with the holding plate 14 c, and the heating element 13 and the holding plate arranged on the inner surface of the semi-cylindrical heating plate 11. A space is formed between the heating element 13c and the heating element 13, and the heating element 13 is held so as to cover the holding member 14 with an interval, so that heat radiation can be suppressed, thereby improving heat efficiency and improving safety.
[0035]
FIG. 6 is a sectional view showing a fourth embodiment of the holding structure for fixing the heating plate 11 to the holding member 14.
[0036]
In the fourth embodiment, the holding member 14 is constituted by a holding plate 14c and semi-cylindrical holding bodies 14p and 14q formed at ends of the holding plate 14c in the longitudinal direction (semi-cylindrical axial direction). The ends of the plate 11 in the longitudinal direction (semi-cylindrical axial direction) are fixed to holders 14p and 14q with screws 14r and 14s.
[0037]
Even with this configuration, the semi-cylindrical heating plate 11 has its circumferential end contacting the holding plate 14c and its cylindrical axial end contacting the semi-cylindrical holding bodies 14p and 14q. Thus, a space is formed between the heating element 13 disposed on the inner surface of the heating plate 11, the holding plate 14c, and the holding bodies 14p and 14q, and the heating element 13 is held so as to cover the holding member 14 at an interval. You.
[0038]
Thereby, since the inner surface of the heating plate 11 is closed, radiation of heat is suppressed, so that thermal efficiency can be improved and safety can be improved.
[0039]
FIG. 7 is a sectional view showing a fifth embodiment of the holding structure for fixing the heating plate 11 to the holding member 14.
[0040]
In the fifth embodiment, a holding portion 14j, a holding portion 14k, and a holding leg portion 14m are configured with a holding member 14 having a T-shaped cross section, and a plate substrate 11a of a semi-cylindrical heating plate 11 is moved in the circumferential direction. One end 11a5 is held by a holding portion 14j, the other end 11a6 in the circumferential direction is held by a holding portion 14k, and the center portion 11a7 is held by a holding leg 14m.
[0041]
In this configuration, the electric insulating layer 12 and the heating element 13 arranged on the inner surface of the plate substrate 11a are divided into two parts so that the holding legs 14m of the holding member 14 directly contact the plate substrate 11a.
[0042]
Next, the mounting structure of the temperature detecting element for detecting the temperature of the heating element will be described. 8A and 8B are cross-sectional views showing a mounting structure of the temperature detecting element. FIG. 8A shows a first mounting structure embodiment, and FIG. 8B shows a second mounting structure embodiment.
[0043]
In the first embodiment of the mounting structure shown in FIG. 8A, the temperature detecting element 21 is adhered to the heating element 13 and is fixed by the sheet metal 22 extended from the holding member 14.
[0044]
The second mounting structure embodiment shown in FIG. 8B has a structure similar to the first mounting structure, except that a hole 14n is provided in the holding member 14, and a sheet metal 22 is mounted from the hole 14n. The element 21 is inserted into a space formed between the heating plate 11 and the holding member 14, and the temperature detecting element 21 is fixed to the heating element 13. According to this configuration, after attaching the heating plate 11 to the holding member 14, the temperature detecting element 21 can be inserted from the hole 14n and attached to the heating element 13. As the temperature detection element 21, a thermistor may be used.
[0045]
FIG. 9 is a cross-sectional view illustrating a structure for supplying power to the heating element. The heating element 13 is provided with a power supply contact terminal 13p at an end in the longitudinal direction (ie, an end in the longitudinal direction (axial direction) of the semi-cylindrical heating plate 11 to which the heating element 13 is fixed). The power supply contact piece 24 is attached to the holding member 14 via an elastic member 23.
[0046]
When the heating plate 11 is attached to and held by the holding member 14, the power supply contact terminal 13 p on the heating element 13 and the power supply contact piece 24 on the holding member 14 come into contact with each other to form a power supply circuit. ing.
[0047]
According to this configuration, the power supply circuit is completed at the same time simply by attaching the heating plate 11 to the holding member 14, and there is no need to separately connect a lead wire to the heating element 13. In addition, since the lead wires are not soldered, deterioration of the heating plate 11, the electrical insulating layer 12, the heating element 13, and the like due to the heat of the soldering operation can be prevented.
[0048]
【The invention's effect】
As described in detail above, the fixing device of the present invention uses a heating plate as a heat source, and the heating plate contacts at least a plate substrate made of a heat conductive material and the fixing rotating body of the plate substrate. Since the heating plate is held by a holding member arranged so as to cover the heating element at an interval with respect to the heating element, In addition to suppressing heat radiation and increasing thermal efficiency, it also has remarkable effects such as being able to enhance safety.It also shortens the rise time from when power is turned on until it reaches a temperature where fixing processing can be performed, A compact and low-cost fixing belt type fixing device with a small number of parts can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view (part 1) illustrating a configuration of a fixing device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view (part 2) illustrating the configuration of the fixing device according to the embodiment of the present invention.
FIG. 3 is a diagram showing a first embodiment of a holding structure for fixing a heating plate to a holding member.
FIG. 4 is a diagram showing a second embodiment of the holding structure for fixing the heating plate to the holding member.
FIG. 5 is a diagram showing a third embodiment of a holding structure for fixing a heating plate to a holding member.
FIG. 6 is a diagram showing a fourth embodiment of a holding structure for fixing a heating plate to a holding member.
FIG. 7 is a diagram showing a fifth embodiment of a holding structure for fixing a heating plate to a holding member.
FIG. 8 is a sectional view showing a mounting structure of the temperature detecting element.
FIG. 9 is a cross-sectional view showing a structure for supplying power to a heating element.
[Explanation of symbols]
Reference Signs List 10 Fixing device 11 Heating plate 11a Plate substrates 11a1, 11a2 Extension portions 11a5, 11a6 of plate substrate End portions 11a7 of plate substrate 12 Insulating layer 13 Heating element 13p Power supply contact terminals 14 Holding member (holding body)
14a, 14b Holder 14c Holder plates 14c1, 14c2 Grooves 14j, 14k Holder 14m Holder legs 14n Holes 14p, 14q Holder 15 Press pad 16 Fixing belt (fixing rotator)
17 Pressure roller (pressure rotating body)
18 opposing roller 21 temperature detecting element 22 sheet metal 23 elastic member 24 power supply contact piece

Claims (5)

A heating plate, a loop-shaped fixing rotator wound around the heating plate and the supporting member and rotatably held, and a pressing rotator pressed against the supporting member via the fixing rotator A fixing device of an image forming apparatus that performs a fixing process by passing a recording medium on which a toner image is formed between the fixing rotator and the pressing rotator,
The heating plate includes at least a semi-cylindrical plate substrate made of a heat conductive material, and a heating element disposed on a surface of the plate substrate opposite to a surface that contacts the fixing rotating body. Semi-cylindrical heating plate,
The fixing device of the image forming apparatus, wherein the heating plate is held by a holding member disposed so as to cover the heating element at a distance from the heating element. The holder is a holder that holds the heating plate at one or both ends of the semi-cylindrical heating plate in the circumferential direction and the cylindrical axial direction. The fixing device for an image forming apparatus according to claim 1, wherein: 2. The holder according to claim 1, wherein the holder is a holder that is arranged on a heating element arrangement side of the heating plate and holds the heating plate at least at a circumferential end and a central portion of the heating plate. 3. Fixing device of the image forming apparatus. 4. The fixing device according to claim 1, wherein a temperature detection element that detects a temperature of the heating element is arranged on the holding body so as to contact the heating element. 5. apparatus. The heating plate, wherein an electrical insulating layer is disposed between the plate substrate and a heating element, and the electrical insulating layer extends outward at least by a predetermined dimension from an end of the heating element. Item 2. A fixing device for an image forming apparatus according to Item 1.

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