JP2016161849A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of achieving energy saving and properly controlling a heating temperature.SOLUTION: A fixing device includes: a pressing member forming a fixing nip part by a belt state fixing member rotated by contacting an unfixed image and the belt state fixing member; a holding member for holding the heating member to heat the belt state fixing member and the heater member; heating control means for controlling the heating of the heater member based on the information detected by temperature detection means; and a heat transferring member interposed between the belt state fixing member and the heater member, brought into contact with the belt state fixing member in the fixing nip part for transferring the heat from the heater member to the belt state fixing member. The heat transferring member includes an extension part extending at least to one of the rotation directions of the belt state fixing member. A portion of the extension part is brought into contact with at least the belt state fixing member, and the temperature detection means is provided in the extension part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and more particularly to a heating type fixing device mounted on such an image forming apparatus.

  The image forming apparatus forms a toner image on an image carrier based on image information, transfers the toner image onto a recording material such as paper or an OHP sheet, and passes the recording material carrying the toner image through a fixing device. The toner image is fixed on the recording material by heat and pressure.

  As a fixing device that realizes energy saving, a technique of heating a film with a resistance heater in which a resistance heating element is formed on a ceramic or glass substrate has been proposed (for example, see Patent Document 1).

  The fixing device described in Patent Document 1 is sandwiched between a plate-like heating body and a pressure roller that are in contact with a thin-walled cylindrical heat-resistant film so that the film and the recording material are brought into close contact with each other, and gives thermal energy to the recording material. It is a configuration. This fixing device can realize energy saving by heating a thin film with a plate-like heating element in which a resistance heating element is formed on a heater substrate such as alumina.

  However, the plate-like heating element described in Patent Document 1 has a problem that the temperature of the resistance heating element cannot be detected properly when the thermistor for detecting the temperature of the heater board is disposed on the heater board.

  An object of the present invention is to provide a fixing device capable of realizing energy saving and appropriately controlling the heating temperature.

In order to solve the above-described problem, a fixing device according to a first aspect of the present invention includes:
A belt-like fixing member that rotates in contact with an unfixed image;
A pressing member that forms a fixing nip portion with the belt-shaped fixing member;
A heater member for heating the belt-shaped fixing member; and a holding means for holding the heater member;
In a fixing device comprising: a heating control unit that controls heating of the heater member based on information detected by a temperature detection unit;
The heater member is composed of a long base material extending in the longitudinal direction of the belt-like fixing member, and a heating element formed on the fixing nip side from the base material,
A heat transfer member that is interposed between the belt-shaped fixing member and the heater member, contacts the belt-shaped fixing member at a fixing nip portion, and transfers heat from the heater member to the belt-shaped fixing member; Have
The heat transfer member has an extending portion extending in at least one of the rotation directions of the belt-shaped fixing member,
The extending portion is at least partially in contact with the belt-shaped fixing member,
The temperature detecting means is provided in the extending portion.

  According to the present invention, it is possible to provide a fixing device capable of realizing energy saving and appropriately controlling the heating temperature.

1 is a configuration diagram schematically showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a configuration diagram schematically illustrating a fixing device of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a configuration diagram schematically illustrating a nip forming member of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a configuration diagram illustrating a heating member of the image forming apparatus illustrated in FIG. 1. It is explanatory drawing explaining the heater member of the image forming apparatus shown in FIG. FIG. 10 is an explanatory diagram for explaining a modification of the heater member of the image forming apparatus shown in FIG. 1. FIG. 10 is an explanatory diagram for explaining a modification of the heater member of the image forming apparatus shown in FIG. 1. FIG. 10 is an explanatory diagram for explaining a modification of the heater member of the image forming apparatus shown in FIG. 1. It is a block diagram which shows schematically the nip formation member which concerns on the 2nd Embodiment of this invention. It is explanatory drawing explaining the modification of the heater member of the image forming apparatus shown in FIG.

  FIG. 1 shows a monochrome printer as an example of an image forming apparatus according to the first embodiment of the present invention, which will be described based on this. Naturally, the present invention applies to a known color image forming apparatus. Is applicable. As is known, a monochrome printer is provided with predetermined devices necessary for forming an image around a photosensitive member 8 as an image carrier, such as a charging unit, an exposure unit, and a developing unit. That is, a charging roller 18 as a charging means, a mirror 20 constituting an exposure means, a developing device 22 having a developing roller 22a as a developing means, a transfer device 10, a cleaning device 24 having a cleaning blade 24a, and the like are arranged. Yes. Then, between the charging roller 18 and the developing device 22, exposure light Lb is irradiated to the exposure unit 26 on the photoconductor 8 via the mirror 20 and scanned. A sheet feeding unit 4 is disposed below the printer, and a registration roller pair (positioning roller pair) 6 is provided in the middle of the sheet conveyance path to the image forming unit. At the end of the sheet conveyance path, a fixing device 12 including a fixing belt 28, a heater member 56, and a pressure roller 30 as main components is provided.

  The paper feed means 4 feeds the paper P as a recording medium stored in a stacked state and the paper P stored in the paper feed tray 14 one by one in order from the top. It has a paper roller 16 and the like. The paper P sent out by the paper supply roller 16 is temporarily stopped by the registration roller pair 6. Then, after correcting the posture deviation, at the timing synchronized with the rotation of the photoconductor 8, that is, the front end of the toner image formed on the photoconductor 8 coincides with the predetermined position of the front end of the sheet P in the transport direction. At timing, it is sent to the transfer portion N by the registration roller pair 6.

  The image forming operation in this printer is performed in the same manner as before. That is, when the photosensitive member 8 starts to rotate, the surface of the photosensitive member 8 is uniformly charged by the charging roller 18, and the exposure light Lb is irradiated and scanned on the exposure unit 26 based on the image information to correspond to an image to be created. An electrostatic latent image is formed. The electrostatic latent image is moved to a position facing the developing device 22 by the rotation of the photosensitive member 8, where toner is supplied to be visualized to form a toner image. The toner image formed on the photoreceptor 8 is transferred onto the paper P that has entered the transfer portion N at a predetermined timing by applying a transfer bias of the transfer device 10. The paper P carrying the toner image as an unfixed image is conveyed toward the fixing device 12, fixed by the fixing device 12, and then discharged and stacked on a paper discharge tray outside the apparatus. Residual toner remaining on the photosensitive member 8 without being transferred at the transfer portion N reaches the cleaning device 24 as the photosensitive member 8 rotates. Then, while passing through the cleaning device 24, it is scraped off and cleaned by the cleaning blade 24a. Thereafter, the residual potential on the photoconductor 8 is removed by a known charge eliminating means and prepared for the next image forming step.

  Next, the configuration of the fixing device according to the embodiment of the present invention will be described with reference to FIG. The fixing device 12 includes an endless fixing belt (belt-shaped fixing member; hereinafter, simply referred to as a fixing belt) 28 that is a flexible heat-resistant film, and a pressure roller 30 that is a pressing member that comes into contact with the outer peripheral surface thereof. And a heater member 56.

  The heater member 56 functions as a nip forming member that forms the fixing nip portion SN with the pressure roller 30 together with the heat transfer member 50 for heat equalization in the axial direction (longitudinal direction) of the fixing belt 28. Also called a heating pad.

  The heat transfer member 50, the heater member 56, and the heater holder 57 as a holding means for holding the heat transfer member 50 are supported by a stay (support member) 61 connected to the apparatus side plate. Therefore, the bending of these members that receive pressure by the pressure roller 30 is prevented, and a uniform nip width is obtained in the longitudinal direction. A low friction sheet may be interposed between the heat transfer member 50 and the inner peripheral surface of the fixing belt 28.

  A first thermistor 34 is provided as a temperature detecting means for detecting the surface temperature of the fixing belt 28 on the downstream side of the fixing nip SN and the upstream side of the heater member 56 in the rotation direction of the fixing belt 28. ing. The heat transfer member 50 is provided with a second thermistor 36 as temperature detection means for detecting the temperature of the heat transfer member 50. On the basis of the detection information of the thermistor, a heating control means 42 for controlling the power source 40 that supplies power to the heater member 56 is provided. The heating control means 42 means a microcomputer including a CPU, ROM, RAM, I / O interface and the like.

  The fixing belt 28 has a nickel base having an outer diameter of 30 mm and a thickness of 10 to 70 μm, an elastic layer coated on the surface of the base, and a release layer formed on the surface. The elastic layer is made of silicone rubber and has a thickness of 50 to 150 μm. The release layer that increases the durability and secures the release property is formed of a fluorine-based resin such as PFA or PTFE and has a thickness of 5 to 50 μm. The substrate is not limited to nickel, and may be formed of a metal such as SUS or a heat resistant resin material such as polyimide (PI).

  The pressure roller 30 has an outer diameter of 30 mm, and includes a solid iron cored bar 30a and an elastic layer 30b formed on the surface of the cored bar 30a. The elastic layer 30b is made of silicone rubber and has a thickness of 5 mm. It is desirable to form a fluororesin (PFA or PTFE) layer having a thickness of about 40 μm on the surface of the elastic layer 30b in order to improve the releasability. As is known, the pressure roller 30 is pressed against the heat transfer member 50 and the heater member 56 via the fixing belt 28 by an urging means. The pressure roller 30 is rotated by driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The fixing belt 28 is rotated by the pressure roller 30.

  Next, the nip forming member will be described. As shown in FIG. 3, the nip forming member includes a heater member 56 and a heat transfer member 50 for heat equalization in the axial direction (longitudinal direction) of the fixing belt 28, and is fixed by the pressure roller 30. A nip portion SN is formed.

  The heater member 56 heats the fixing belt 28 through the heat transfer member 50 to increase the temperature of the fixing belt 28 and heat and fix the unfixed image conveyed to the fixing nip portion SN.

  As shown in FIG. 4, the heater member 56 is a long base material 56b extending in the longitudinal direction (axial direction) of the fixing belt 28, and a heating element disposed on the fixing nip SN side from the base material 56b. And a resistance heating element 56a. Further, a resistance heating element 56a made of, for example, ruthenium oxide is printed on the low thermal conductivity base material 56b made of glass, ceramic or the like, and fired, and an overcoat (OC) layer is formed thereon. 56c may be formed. The OC layer 56c located on the fixing nip SN side from the base material 56b is formed of glass or the like, and is thinner than the base material 56b, and is more likely to transfer heat to the OC layer side 56c than to the heat transfer to the base material 56b side. Therefore, the heating efficiency of the fixing belt 28 can be improved.

  A heater holder 57 as a holding means for holding the heater member 56 is supported by a stay (support member) 61 connected to the apparatus side plate, prevents the member from being bent by the pressure received from the pressure roller 30, and is uniform in the longitudinal direction. The nip width can be obtained. The heater holder 57 is in contact with the back surface of the heater member 56 and holds the heater member 56.

  By the way, the heater holder 57 easily receives a heat from the heater member 56 and becomes high temperature, and may be damaged. Therefore, the heater holder 57 is formed of a resin having high heat resistance such as LCP. As a result, the heater holder 57 can be prevented from being damaged. The heater holder 57 is brought into contact with at least a part of the back surface of the heater member 56. That is, the heater holder 57 is brought into contact with the heater member 56 at a position not facing the resistance heating element 56a. Therefore, the amount of heat flowing from the heater member 56 to the heater holder 57 can be reduced, and heat can be efficiently transferred to the heat transfer member 50 on the high heat conduction side, and thus to the fixing belt 28.

Next, the heat transfer member 50 will be described.
The heat transfer member 50 is made of a high heat conductive material such as copper or aluminum, and efficiently transfers the heat of the heater member 56 to the fixing belt 28. In addition, the heat transfer member 50 contributes to an improvement in heat transfer performance in the longitudinal direction of the heater member 56, and can reduce a temperature deviation in the longitudinal direction of the fixing belt 28. Furthermore, between the heater member 56 and the heat transfer member 50, a heat conductive grease, a heat conductive sheet, or the like is interposed, so that the adhesion is improved, so that the nip side surface (surface) of the heater member 56 and It is possible to improve the heat transfer to the front surface side than the opposite side surface (back surface) and improve the heating characteristics of the fixing belt 28.

  Further, the heat transfer member 50 contacts the fixing belt 28 at the fixing nip SN. Further, the heat transfer member 50 in the present embodiment has an extending portion 50a extending upstream of the fixing nip SN in the rotation direction of the fixing belt 28, and the extending portion 50a also contacts the fixing belt 28. To do. By contacting the fixing belt 28 in a range other than the fixing nip portion SN, that is, the extending portion 50a, a heat transfer time to the fixing belt 28 can be secured. Note that the extending portion of the heat transfer member 50 is not limited to this mode, and extends in the upstream and / or downstream of the fixing nip SN in the rotation direction of the fixing belt 28 and contacts the fixing belt 28. Also good.

  The extending portion 50 a of the heat transfer member 50 is provided with a second thermistor 36 that detects the temperature of the heat transfer member 50. When the second thermistor 36 is provided on the heat transfer member 50, the second thermistor 36 can directly measure the temperature of the heat transfer member 50, so that an accurate temperature can be detected instantaneously. Furthermore, since the heater member 56 has a high temperature exceeding 250 ° C., the second thermistor 36 is not in contact with the heater member 56, so the second thermistor 36 having low heat resistance can be used, and the reliability can be improved. .

Next, the heater member 56 will be described in detail.
As shown in FIG. 5, the heater member 56 has a long resistive heating element 56 a in the longitudinal direction thereof, that is, the direction orthogonal to the paper transport direction. A common wiring Wcom and individual wirings W1 to W5 are connected to the resistance heating element 56a. The common wiring Wcom constituting the first current-carrying electrode and the individual wirings W1 to W5 constituting the second current-carrying electrode form a comb-like conductive portion for the resistance heating element 56a. Since the common wiring Wcom and the individual wirings W1 to W5 form a comb-like conductive portion, the resistance heating element 56a has a plurality of heating regions (H1 to H5). Each heating region can be independently controlled by turning on / off the individual wirings W1 to W5. The first thermistor 34 that detects the surface temperature of the fixing belt 28 and the second thermistor 36 that detects the temperature of the heat transfer member 50 are arranged corresponding to each heating region.

  Each heating region may be configured such that heating regions (H1 and H5, H2 and H4) located symmetrically from the longitudinal center can be turned ON / OFF simultaneously. As a result, the number of switch elements required for heating control, such as triacs and FELs, can be reduced.

  In addition, the heater member 56 is not limited to what forms a some heating area | region with a comb-shaped electrode with respect to a elongate resistive heating element. For example, as shown in FIG. 6, a plurality of individual resistance heating elements 56 a 11 to 56 a 53 may be arranged in the longitudinal direction of the heater member 56. A plurality of individual resistance heating elements 56a11 to 56a53 constitute each heating region (H1 to H5). The individual resistance heating elements 56a11 to 56a53 each constitute a heating part. In the heating region H3, ten heating portions are formed by the ten individual resistance heating elements 56a31 to 56a310, and the region H3 is heated. The interval at which the individual resistance heating elements are adjacent to each other is kept substantially constant.

  Even in such a configuration, each heating region may be configured such that heating regions (H1 and H5, H2 and H4) located symmetrically from the longitudinal center can be turned ON / OFF simultaneously. This reduces the number of switching elements such as triacs and FETs for ON / OFF.

  In addition, in the above-mentioned embodiment, although the heating area | region is divided | segmented into five of H1-H5, it is not limited to this aspect. For example, it is possible to divide into more than 9 divisions or less into 3 divisions. The present invention is effective even with a heater that is not divided into a plurality of heating regions, and can be applied to this.

  Each heating region can be independently controlled by turning on / off the individual wirings W1 to W5. Based on the detection information of the thermistors 34 and 36 and the sheet passing size information, the temperature of each heating region is controlled by the heating control means 42, and the heating rate of the heater member is changed. By controlling the heating according to the sheet passing size information, a situation where the temperature of the non-sheet passing area becomes too high can be avoided, and damage to the member and image quality deterioration due to excessive temperature rise in the non-sheet passing area can be suppressed. The power supply may be completely stopped (turned off) at a portion corresponding to the non-sheet passing area. However, if the temperature is excessively lowered, it may not be in time to rise to the fixing temperature in the next image area. For this reason, the fixing belt 28 is temperature-controlled so as to be kept at a second target temperature that is lower than the first target temperature corresponding to the image area but higher than the room temperature, and corresponds to the non-sheet passing area. Power is also supplied to the part.

  In addition, the extension part 50a may be formed in the partial area | region of the longitudinal direction of the heat-transfer member 50, as shown in FIG. By forming the extending portion 50a in a partial region in the longitudinal direction of the heat transfer member 50, the overall heat capacity of the heat transfer member 50 can be reduced, and the temperature detection performance is also improved.

  In addition, the 2nd thermistor 36 which detects the temperature of the heat-transfer member 50 may be arrange | positioned at several extension part 50a1-50a5 corresponding to each heating area | region H1-H5, as shown in FIG.

  Subsequently, an image forming apparatus according to a second embodiment of the present invention will be described. Note that components common to those in the image forming apparatus according to the first embodiment are denoted by corresponding reference numerals and detailed description thereof is omitted, and different components are described in detail with reference to the drawings.

  The second embodiment is different from the first embodiment in that the shape of the heat transfer member is different. This will be specifically described below.

  As shown in FIG. 9, the heat transfer member 150 of the present embodiment contacts the fixing belt 28 in the fixing nip SN. Furthermore, the heat transfer member 150 in the present embodiment has an extending portion 150 a extending downstream in the rotation direction of the fixing belt 28, and the extending portion 150 a also contacts the fixing belt 28. Since the temperature of the heat transfer member 150 is higher on the downstream side than on the upstream side in the rotation direction of the fixing belt 28, the temperature of the high temperature portion can be detected, so that a safe configuration can be achieved.

  Further, as shown in FIG. 10, the extending portion 150 a may be configured not to contact the fixing belt 28 in the downstream end region of the fixing nip SN. It is desirable to arrange the second thermistor 36 in a region where the extending portion 150a does not contact the fixing belt 28. Since the second thermistor 36 is disposed in a region where the fixing belt 28 of the extending portion 150a is not in contact with the second thermistor 36, the temperature of the extending portion 150a detected by the second thermistor 36 is easily increased, and the temperature changes in a short time. Can be detected.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this. It should be noted that the materials and dimensions of each component introduced in the above-described embodiment are merely examples, and it is needless to say that various materials and dimensions can be selected within a range where the effects of the present invention can be exhibited.

28 fixing belt (an example of a belt-like fixing member)
30 Pressure roller (an example of a pressing member)
36 Second thermistor (temperature detection means)
42 Heating control means 50 Heat transfer member 50a Extension part 56 Heater member 56a Resistance heating element (an example of heating element)
56b Base material 57 Heater holder (an example of holding means)
SN fixing nip

JP-A-6-95540

Claims (8)

A belt-like fixing member that rotates in contact with an unfixed image;
A pressing member that forms a fixing nip portion with the belt-shaped fixing member;
A heater member for heating the belt-shaped fixing member; and a holding means for holding the heater member;
In a fixing device comprising: a heating control unit that controls heating of the heater member based on information detected by a temperature detection unit;
The heater member is composed of a long base material extending in the longitudinal direction of the belt-like fixing member, and a heating element formed on the fixing nip side from the base material,
A heat transfer member that is interposed between the belt-shaped fixing member and the heater member, contacts the belt-shaped fixing member at a fixing nip portion, and transfers heat from the heater member to the belt-shaped fixing member; Have
The heat transfer member has an extending portion extending in at least one of the rotation directions of the belt-shaped fixing member,
The extending portion is at least partially in contact with the belt-shaped fixing member,
The fixing device according to claim 1, wherein the temperature detecting unit is provided in the extending portion.   The fixing device according to claim 1, wherein the holding unit is in contact with the heating member at a position not facing the heating element.   The fixing device according to claim 1, wherein the extending portion extends downstream from the fixing nip portion in the rotation direction of the belt-shaped fixing member.   The fixing device according to claim 1, wherein the extending portion extends upstream of the fixing nip portion in the rotation direction of the belt-shaped fixing member.   The fixing device according to claim 1, wherein the extending portion is formed in at least a partial region in a longitudinal direction of the heat transfer member. A plurality of the temperature detecting means in the longitudinal direction of the belt-shaped fixing member;
The fixing device according to claim 5, wherein each temperature detection unit has an extending portion.   6. The fixing device according to claim 1, wherein a region of the extending portion to which the temperature detection unit is attached is not in contact with the belt-shaped fixing member.   An image forming apparatus comprising the fixing device according to claim 1.

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