JP2003337484A - Heating device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the temperature rising of a non-paper, passing part with an inexpensive configuration. <P>SOLUTION: In the heating device of a film heat system, heating elements are provided on both sides of a hater substrate. One of the heating elements is made shorter than the other. When small-size paper is passed through, power is supplied to only the shorter heating element, thereby preventing an increase in the temperature of the area where paper is not passed through. A thermister is an external contact type. Because the width of the substrate can be made narrow in comparison with the structure in which heating elements for large-size paper and small-size paper are provided on one side of the substrate, the costs can be reduced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device such as a copying machine and a laser beam printer, and an image forming apparatus equipped with the heating device.

[0002]

2. Description of the Related Art Conventionally, for example, a recording material heating apparatus for heating and fixing an image includes a heating roller which is maintained at a predetermined temperature and a pressure roller which is pressed against the heating roller through an elastic layer. A heat roller method is widely used in which a recording material as a heated object is heated while being nipped and conveyed. Also,
Besides this, flash heating method, open heating method,
Various methods and configurations such as a hot plate heating method are known and put into practical use.

Recently, instead of such a system, a heater 6 fixedly supported as shown in FIG.
A heat-resistant vertebra film (fixing film) 2 that is conveyed while being pressed against the heating body 6 and a recording material P as a heated body through the film 2 and a pressing body (pressing roller) ) 4 and applying heat of the heating body 6 to the recording material P through the film 2 to heat and fix the unfixed image formed and carried on the recording material surface to the recording material surface. A heat fixing system (film heating system heating device) has been devised.

In such a film heating type heating device or image heating fixing device, a low heat capacity heating member can be used as a heating member. For this reason, it is possible to save power and shorten the wait time (quick start) as compared with conventional devices such as a heat roller system and a belt heating system which are contact heating systems.

[0005]

In the above-mentioned film heating type heat fixing device, when a recording material having a width smaller than the maximum size which can be passed (hereinafter referred to as a small size sheet) is passed, the non-sheet passing portion Since the heat is not taken by the recording material, the temperature becomes higher than that in the paper passing portion (temperature rise in non-paper passing portion). When the temperature rise in the non-sheet passing portion is deteriorated, the heater, the heater stay, the fixing film, and the pressure roller are deteriorated, which may cause a defect in the image. In particular, when a thick recording material with a width smaller than the maximum size (cardboard, envelope, etc., referred to as small size cardboard in the following) is fed in a double feed, a large amount of heat is taken by the recording material in the paper passing section. Moreover, since the temperature control is performed based on the output of the temperature detecting element provided in the paper passing portion, a large amount of electric power is supplied to the heater. On the other hand, in the non-sheet passing portion, heat is not taken by the recording material, so that the temperature becomes extremely high, and the heater, the heater stay, the fixing film, and the pressure roller may be damaged.

In order to solve this problem, as shown in FIG. 7, two resistance heating elements are provided on one surface (a film sliding surface or a non-film sliding surface) of the heater substrate, one of which is the maximum passage of the recording material. It is conceivable to make one longer than the paper area and shorter than that, and to energize only the shorter resistance heating element when passing small size paper.

Further, a method of providing not only two resistance heating elements corresponding to the paper width of various small size papers but also selecting a resistance heating element to be energized according to the paper width of the small size paper to be passed is also considered. To be Further, although there is only one resistance heating element, a method has been proposed in which the conductive pattern is branched in the non-sheet passing portion so that the resistance heating element in the non-sheet passing portion is not energized when passing small-sized paper. ing. Although any of the above methods is effective in raising the temperature of the non-sheet passing portion, there is a problem in terms of cost because it is necessary to widen the width of the heater substrate due to the configuration.

Therefore, it is an object of the present invention to provide a heating device which can prevent the temperature rise of the non-sheet passing portion at low cost, and an image forming apparatus which uses the heating device as an image fixing means.

[0009]

The above object can be achieved by the heating device and the image forming apparatus according to the present invention. The present invention is a heating device and an image forming apparatus having the following configurations.

(1) A heating body, a heat-resistant fixing film that slides in contact with the heating body, and the fixing film is driven, and a material to be heated is brought into close contact with the aged body through the fixing film. In a heating device that has a pressure member, and heats the material to be heated by sandwiching and conveying the fixing film and the material to be heated in a nip portion formed by the heating body and the pressure member, The heating device is characterized in that a resistance heating element is provided on both sides of a film sliding surface and a non-film sliding surface on a substrate.

(2) In the heating device according to (1), the resistance heating elements provided on both surfaces of the heating element substrate have different lengths in the longitudinal direction of the heating element.

(3) In the heating device according to (1) or (2), the temperature sensing element for detecting the temperature of the heating element is provided, and the temperature sensing element contacts the non-film sliding surface of the heating element. A heating device characterized in that

(4) In the heating device described in (1) to (3), the resistance heating elements provided on both surfaces of the aged body substrate can be independently energized to control the size of the material to be heated. A heating device characterized by changing the heat generation ratio of the resistance heating elements on both sides of the substrate according to the above.

(5) In the heating device described in (1) to (4), when a material to be heated having a width narrower than a material to be heated having the maximum width that can be supplied to the heating device and used, A heating device, wherein electricity is supplied only to a resistance heating element having a short heating element length.

(6) In the heating device described in (1) to (5), one resistance heating element is longer than the maximum width of the material to be heated that can be supplied to the heating device and used, and the other resistance heating element is A heating device which is shorter than one resistance heating element and longer than the minimum width of a material to be heated that can be supplied to the heating device and used.

(7) The heating device according to any one of (1) to (6), wherein the substrate of the heating body is made of ceramics.

(8) An image forming apparatus using the heating device described in (1) to (7) as an image fixing means.

By using the heating device and the image forming apparatus having the above-mentioned structure, it is possible to prevent the temperature rise of the non-sheet-passing portion with a low cost structure and to deteriorate or damage the heating body, the fixing film, the pressure roller, etc. Can be prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 shows a main part of a laser beam printer as an image forming apparatus in this embodiment. In FIG. 5, reference numeral 101 denotes an organic photosensitive drum as an image bearing member, and 102.
Is a charging roller as a charging member, 103 is a laser exposure device, 104 is a developing device including a developing sleeve and a developing blade, and one-component magnetic toner, 105 is a cleaning blade, 106 is a transfer roller, and 107 is a fixing device. The organic photosensitive drum 101 is uniformly charged to a negative charge by the charging device 102, and the laser exposure device 103
An electrostatic latent image is formed on the organic photosensitive drum 101 by the laser beam from the. Next, the charged toner in the developing device 104 adheres to the electrostatic latent image on the organic photosensitive drum 101 to form a visible image, which is transferred onto paper on the transfer roller 106 and fixed by the fixing device 107. The cleaning blade 105 removes the toner remaining on the organic photosensitive drum 101. An image is formed by the operation of each unit described above.

FIG. 2 is a schematic block diagram of an example of an image heating and fixing apparatus of the present embodiment, which uses the film heating method and has a maximum sheet passing width of A4 size. This device is disclosed in JP-A-4-440.
75-44083 gazette, the same 4-204980-204.
This is a so-called tensionless type device disclosed in Japanese Patent Publication No. 984.

This tensionless type device uses an endless belt-shaped or cylindrical heat-resistant film, and at least a part of the circumference of the film is always tension-free (a state where no tension is applied),
The film is a device that is rotationally driven by the rotational driving force of the pressure member.

In FIG. 2, reference numeral 1 is a support (stay) for a heating element that also serves as a film guide member, 2 is an endless heat-resistant film, 3 is a heating element (heater), and the film 2
Is externally fitted to the stay 1 including the heating body 3. In the present embodiment, the inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heating element 3 are 3 in the film 2.
Since the film 2 is made larger by about mm, the film 2 is externally fitted with a margin in the circumferential length.

The stay 1 can be made of a high heat resistant resin such as polyimide, polyamide imide, PEEK, PPS, liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like. In this embodiment, a liquid crystal polymer is used.

The film 2 has a film thickness of 100 in order to reduce the heat capacity and improve the quick start property.
a monolayer film such as PTFE, PFA or FEP having a heat resistance of not more than 50 μm, preferably not more than 50 μm and not less than 20 μm,
Or polyimide, polyamide imide, PEEK, PE
PTFE, PF on the outer peripheral surface of the film such as S, PPS
A composite layer film coated with A, FEP or the like can be used. In this embodiment, the outer peripheral surface of a polyimide film having a thickness of about 40 μm coated with PTFE was used.

Reference numeral 4 is a pressure roller as a film outer surface contact drive means for forming a pressure contact nip portion (fixing nip portion) N by sandwiching the film 2 with the heating body 3 and driving the film 2 to rotate. The film driving roller / pressurizing roller 4 comprises a core metal 4a, an elastic layer 4b made of silicone rubber or the like, and an outermost release layer 4c, and is provided with a predetermined pressing force by a bearing means / urging means (not shown). It is arranged so as to be sandwiched by 2 and pressed against the surface of the heating element 3. The rotational force acts on the film 2 by the frictional force between the pressure roller 4 and the outer surface of the film due to the rotational driving of the pressure roller 4. In this embodiment, aluminum is used as the core metal 4a of the pressure roller 4 and silicone rubber is used as the elastic layer 4b.

FIG. 3 is a schematic plan view of the heating element 3 in this embodiment. The heating body 3 is an elongated substrate 31 having heat resistance, insulation, and good thermal conductivity whose longitudinal direction is a direction perpendicular to the transport direction a of the film 2 or the recording material P as a heated body.
The resistance heating elements 32, 33 formed on the front surface (film sliding surface) and the back surface (non-film sliding surface) of the substrate 31 along the length of the substrate at the center portion in the lateral direction of the substrate, and the resistors. Heat-resistant overcoat layers 34 and 35 that protect the front and back surfaces of the heating elements on which the heating elements 32 and 33 are formed, and the power supply electrodes 21 to 23 at both longitudinal ends of the resistance heating elements 32 and 33.
Is a heating body with a low heat capacity.

In FIG. 3, the shaded portion shows the resistance heating element. In this embodiment, the resistance heating element 32 on the front surface is longer than the maximum sheet passing area, and the resistance heating element 33 on the back surface is the resistance heating element 32 on the front surface. It is shorter and longer than the small size paper feed area. The small-size paper passing area described here can be selected from small-size paper that can be passed through the heating device. In the present embodiment, the small-size paper having a width of 110 mm corresponds to the resistance heating element 33 on the back surface. The length was 114 mm. Here, the reason why the resistance heating element 33 is made longer than the area through which the small size paper passes is to ensure the fixability up to the edge of the small size paper. The overcoat layer 35 on the back surface is provided to prevent resistance fluctuation due to oxidation of the resistance heating element 33 on the back surface and to secure the dielectric strength voltage. The length of the resistance heating element 32 on the surface was 220 mm.

FIG. 1 is a sectional view of the heating element 3 in this embodiment. Reference numeral 5 is a temperature detecting element for detecting the temperature of the heating element 3. In the film heating type heating device, a configuration in which a chip thermistor is mounted on the back surface of the heater substrate as a temperature detecting element is also used. However, in the present embodiment, a bead thermistor is used as the temperature detecting element 5 and the substrate 3 is applied with a predetermined contact pressure.
1) The back surface (on the overcoat layer 35) is contacted. The temperature measuring element 5 is attached to the stay 1 by means not shown.
It is fixed to. By adopting the configuration of this embodiment, it is not necessary to provide a chip thermistor and a conductive pattern for the thermistor on the back surface of the substrate 31, and it is possible to form the resistance heating element 33 on the back surface without widening the substrate width. Become.

The heating substrate 31 is made of a material such as alumina or aluminum nitride. In this embodiment, an alumina substrate having a thickness of 1 mm, a width of 7 mm and a length of 270 mm is used. The resistance heating elements 32 and 33 are made of Ag, for example.
/ Pd (silver-palladium), RuO ₂ , Ta ₂ N or the like is formed by applying an electric resistance material in a linear or linear shape by screen printing or the like.
Both sides have Ag / Pd screen printing thickness of about 10
It was formed by coating to a thickness of 1 μm and a width of 1 mm. Power supply electrodes 21 to
23 used the Ag / Pd screen printing pattern layer. The overcoat layers 34 and 35 are about 5 on both the front and back surfaces.
A heat resistant glass layer having a thickness of 0 μm was used.

The heating element 3 is fixedly arranged so that the surface side on which the resistance heating element 32 is formed and exposed is exposed downward and is held on the lower surface side of the stay 1 having rigidity and heat resistance.

The heating element 3 is a resistance heating element 32 or 33.
The resistance heating element 32 or 33 heats up due to the power supply to the power supply electrodes 21 to 23 at both longitudinal ends, and the temperature rise is detected by the temperature detecting element 5. The output of the temperature detecting element 5 is A / D converted and taken into the CPU 24, and based on the information, the AC voltage of the AC power supply 26 for energizing the resistance heating element 32 or 33 by the triac 51 or 52 is heated by phase, wave number control or the like. The temperature of the heating element 3 is controlled by controlling the body-conducting power. That is, when the temperature detected by the temperature detecting element 5 is lower than a predetermined set temperature, the heating body 3 is heated, and when the temperature is higher than the set temperature, the energization is controlled so that the aging body 3 has a constant temperature during fixing. Adjusted.
The resistance heating elements 32 and 33 can be independently energized, and which resistance heating element is energized is determined by the paper size. Details of this control will be described later.

Then, in a state where the temperature of the heating element 3 rises to a predetermined level and the rotational peripheral speed of the film 2 due to the rotation of the pressing roller 4 is stabilized, the heating element 3 and the pressing roller are sandwiched with the film 2 interposed therebetween. An image forming portion (transfer portion) (not shown) is a recording material P as an object to be image-fixed between the film 2 in the pressure contact nip portion N formed by
The heat of the heating element 3 is applied to the recording material P via the film 2 by being nipped and conveyed through the pressure contact nip portion N together with the film 2, and the unfixed visible image (toner image) on the recording material P is obtained. T is heated and fixed on the surface of the recording material P. The recording material P passing through the pressure nip portion N is separated from the surface of the film 2 and conveyed.

In the present embodiment, in order to prevent the temperature rise in the non-sheet passing portion, small size paper (paper width 110 m in this embodiment) is used.
When passing a recording material P of m or less), only the resistance heating element 33 on the back side is energized, and when passing a recording material P of any other size, only the resistance heating element 32 on the front side is energized (resistance of the back side). The heating element 33 may be energized at the same time). Also,
When passing small size paper, not only the resistance heating element 33 on the back side is energized, but also the resistance ripening body 32 on the front side is energized,
The amount of heat generated by the resistance heating element 32 on the front surface is determined by the resistance heating element 33 on the back surface.
It is also possible to control the temperature to be less than the heat generation amount in order to reduce the temperature rise in the non-sheet passing portion. Similarly, when the recording material P other than small size paper is passed, control may be performed such that both resistance heating elements are energized to change the heat generation ratio of both.

The results of measuring the temperature rise of the non-sheet passing portion when passing a small size sheet using the heating apparatus having the configuration of the present embodiment are shown below. When passing small-sized paper, control is performed so that only the resistance heating element 33 on the back side is energized, an envelope with a paper width of 110 mm is double-fed, and 10 sheets are continuously fed. It was measured using a pair. As a result, the highest temperature reached in the non-sheet passing portion was about 180 ° C., and no deterioration or damage was observed in the stay 1, the film 2, the heating element 3, and the pressure roller 4. For comparison, a resistance heating element is provided only on the surface of the substrate, and other configurations are performed by using a heating device similar to this embodiment.
As a result of conducting a test under the same conditions, the maximum temperature reached in the non-sheet passing portion is about 300 ° C., the contact surface of the heating element 3 of the stay 1 melts in the non-sheet passing portion, and the surface of the pressure roller 4 deteriorates. did. In this comparison, the fixing temperature was set so that the fixing properties of the small size papers were equal in both heating devices.

Even with the configuration of this embodiment, the paper width is 110 mm.
When a smaller recording material is passed, the resistance heating element 33 on the back surface protrudes into the non-sheet passing portion, so that the temperature rise of the non-sheet passing portion occurs. However, compared with the case where a recording material having a paper width of less than 110 mm is passed through a heating device (a heating device for comparison as described above) in which a resistance heating element is provided only on the surface of the substrate, the resistance present in the non-sheet passing portion is increased. Since the area of the heating element is small, the temperature of the non-sheet passing portion is sufficiently low and there is no problem.

In order to secure the fixing property, it is necessary to widen the width of the resistance heating element to some extent. Therefore, when two resistance heating elements having different heating element lengths are formed on one surface of the substrate and the longer resistance heating element is used to secure the fixing property of the recording material having the maximum sheet passing width,
The width of the longer resistance heating element needs to be the same as that of the case where one resistance heating element is formed on one surface of the substrate. Therefore, if the shorter resistance heating element is also formed on the same surface, it becomes necessary to widen the substrate width accordingly. In the present embodiment, since it is sufficient to secure a width capable of forming one resistance heating element, it is possible to reduce the substrate width as compared with the case where two resistance heating elements having different heating element lengths are formed on one surface of the substrate, and the cost is low. become.

After all, by using the structure of the present embodiment, it is possible to prevent the temperature rise of the non-sheet passing portion with a low cost structure, which causes deterioration of the heating element, the fixing film, the pressure roller, and the like.
It is possible to prevent damage.

In the present embodiment, the heating device is used as an example when the recording material is fed through the center, but the present invention is also applicable to a heating device where the recording material is fed as the end reference.

In this embodiment, the resistance heating element 32 on the front surface and the resistance heating element 33 on the back surface are made of the same material and in the same position in the substrate width direction, but different materials or different positions in the substrate width direction may be selected. It is possible.

In this embodiment, the resistance heating element 32 on the front surface and the low resistance heating element 33 on the back surface are provided one by one, but the present invention is also applicable to the case where a plurality of resistance heating elements are provided on both the front surface and the back surface. is there.

(Embodiment 2) In the present embodiment, as in the first embodiment, resistance heating elements are provided on both sides of the substrate 31 of the heating element 3, and one resistance heating element is more effective than the other resistance heating element. Also, when passing small size paper, energize only the short resistance heating element. The difference from the first embodiment is that the resistance heating element 32 on the front surface is shorter than the resistance heating element 33 on the back surface. FIG. 4 shows a plan view of the heating element 3 according to this embodiment. The other configurations of the heating device and the image forming apparatus and the method of controlling energization to the resistance heating element are the same as those in the first embodiment.

In the structure of the present invention, the resistance heating element can heat the recording material more efficiently when it is formed on the front surface than when it is formed on the back surface. Therefore, in the configuration of the present embodiment, when recording materials other than small-sized paper are passed, more electric power is required than in the configuration of the first embodiment, and more electric power is required to secure the same fixability. It is said that On the other hand, in the case of passing small size paper, the configuration of the present embodiment has higher thermal efficiency, so that power consumption can be suppressed.

Also in this embodiment, as in the first embodiment, the temperature rise of the non-sheet passing portion can be prevented with a low cost structure.

In the present embodiment, the heating device for feeding the recording material with the center as a reference is taken as an example, but the present invention is also applicable to the heating device for feeding the recording material with the end as a reference.

In the present embodiment, the resistance heating element 32 on the front surface and the resistance heating element 33 on the back surface are made of the same material and in the same position in the substrate width direction, but different materials or different positions in the substrate width direction may be selected. It is possible.

In this embodiment, one low resistance heating element 32 is provided on the front surface and one resistance heating element 33 is provided on the back surface. However, the present invention is also applicable to the case where a plurality of resistance heating elements are provided on both the front surface and the back surface. is there.

[0048]

As described above, by using the heating device and the image forming apparatus of the present invention, it is possible to prevent the temperature rise of the non-sheet passing portion with a low cost structure, and to prevent the heating member, the fixing film, and the heating. It is possible to prevent deterioration and damage of the pressure roller and the like.

[Brief description of drawings]

1 is a cross-sectional view of a heating element according to the present invention.

FIG. 2 is a schematic configuration diagram of a heating device (film heating type image heating and fixing device) according to the present invention.

FIG. 3 is a plan view of a heating body according to the first embodiment.

FIG. 4 is a plan view of a heating body according to the second embodiment.

FIG. 5 is a diagram showing a main part of a laser beam printer according to the present invention.

FIG. 6 is a schematic configuration diagram of a conventional heating device.

FIG. 7 is a plan view of a conventional heating element.

[Explanation of symbols]

1 stay 2 fixing film 3 heater (heating body) 4 pressure roller 4a core metal 4b elastic layer 4c Release layer 5 Temperature measuring element 6 Conventional heating element 7 Conventional temperature measuring element 24 CPU 31 substrate 32 Surface low anti-heating element 33 Resistance heating element on the back 34,35 Overcoat glass layer 101 Organic photosensitive drum 102 charging device 103 Laser exposure device 104 developing device 105 cleaning blade 106 transfer roller 107 fixing device a Recording material conveyance direction N fixing nip P recording material T toner

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H033 AA03 AA24 BA25 BA26 BA27                       BA32 BE03 CA07 CA17 CA30                       CA48                 3K034 AA02 AA10 AA20 AA34 BA05                       BA13 BB06 BB14 BC04 BC13                       FA39                 3K058 AA13 AA22 AA45 BA18 CA12                       CA22 CA61 CB02 CB14 CE02                       CE19 CE23 CE29 DA01 DA06                       GA06

Claims (8)

[Claims] 1. A heating body, a heat-resistant fixing film that slides in contact with the heating body, a pressure that drives the fixing film, and causes a material to be heated to adhere to the heating body via the fixing film. A heating device for heating a material to be heated by sandwiching and carrying the fixing film and the material to be heated together with a nip portion formed by the heating body and the pressure member, The heating device is characterized in that the body is formed by providing a resistance heating element on both the film sliding surface and the non-film sliding surface on a substrate. 2. The heating device according to claim 1, wherein the resistance heating elements provided on both surfaces of the heating element substrate have different lengths in the longitudinal direction of the heating element. 3. The heating device according to claim 1,
A heating device comprising a temperature detecting element for detecting the temperature of the heating body, the temperature detecting element being in contact with a non-film sliding surface of the heating body substrate. 4. The heating device according to claim 1, wherein
The resistance heating elements provided on both sides of the heating element substrate can be independently energized and controlled, and the heat generation ratio of the resistance heating elements on both sides of the substrate is changed according to the size of the material to be heated. Heating device. 5. The heating device according to claim 1, wherein
A heating device, wherein when a material to be heated having a width narrower than the maximum width of the material to be heated supplied to the heating device is passed, only the resistance heating element having a short heating element length is energized. 6. The heating device according to claim 1, wherein
One resistance heating element is longer than the maximum width of the heated material that can be supplied to the heating device, the other resistance heating element is shorter than one resistance heating element and can be used by supplying it to the heating device. A heating device characterized by being longer than the minimum width of the material. 7. The heating device according to claim 1, wherein
The heating device, wherein the substrate of the heating body is made of ceramics. 8. An image forming apparatus using the heating device according to claim 1 as an image fixing means.