JP5011149B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device.

  An electrophotographic image forming apparatus that forms an image based on an electrophotographic method can easily form an image having good image quality, and is widely used in a copying machine, a printer, a facsimile machine, a multifunction machine, and the like. Among them, image forming apparatuses capable of full color printing are rapidly spreading.

  An electrophotographic image forming apparatus (hereinafter simply referred to as “image forming apparatus”) includes, for example, a photoconductor, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. The image forming apparatus is an apparatus that forms an image on a recording medium by performing a charging process, an exposure process, a developing process, a transfer process, and a fixing process using the photoreceptor and these means.

  For example, a heat roller fixing type fixing device is used as a fixing device that performs the fixing process. A heat roller fixing type fixing device includes a fixing roller and a pressure roller, which are a pair of rollers in pressure contact with each other. Heating means such as a halogen heater is disposed inside and / or one of the fixing roller and the pressure roller.

  In the fixing process, after the roller pair is heated to a predetermined temperature required for fixing (hereinafter referred to as “fixing temperature”) by the heating means, the recording medium on which the unfixed toner image is formed is pressed between the fixing roller and the pressure roller. To the fixing nip portion. The unfixed toner image passing through the fixing nip is fixed on a recording medium such as paper by heat transmitted from both or one of the fixing roller and the pressure roller and the pressure of the fixing roller and the pressure roller.

  A fixing device provided in an image forming apparatus capable of full-color printing uses a fixing roller (hereinafter referred to as “elastic roller”) provided with an elastic layer made of, for example, silicone rubber. When the elastic roller is used, the elastic layer on the surface of the elastic roller is elastically deformed corresponding to the unevenness of the unfixed toner image in the fixing nip portion, and the elastic roller and the toner image come into contact so as to cover the toner image. As compared with the above, it is possible to improve the adhesiveness for a color unfixed toner image having a large amount of toner. In addition, due to the strain relief effect of the elastic layer on the surface of the elastic roller, it is possible to improve the releasability of the color toner that is more easily offset than a single color image. Specifically, the elastic layer that has been compressed and distorted at the fixing nip portion is released from the distortion at the exit of the fixing nip portion. As a result, the adhesion force of the elastic layer to the toner image is reduced, and the releasability is improved. Further, the nip shape, which is the shape of the fixing roller and the pressure roller in the fixing nip portion, is convex toward the fixing roller (reverse nip shape), so that the separation performance between the fixing roller and the recording medium can be improved. Accordingly, self-stripping that allows the recording medium and the fixing roller to be peeled off without using, for example, a peeling claw as a peeling means for peeling the fixing roller and the recording medium can be realized. Can be eliminated.

  In such a fixing device provided in an image forming apparatus capable of full-color printing, it is necessary to widen the width of the fixing nip portion (hereinafter referred to as “nip width”) in order to cope with an increase in speed. As means for widening the nip width, there are two methods of increasing the elastic roller diameter and increasing the elastic layer of the elastic roller. However, since the thermal conductivity of the elastic layer of the elastic roller is very low, if the elastic layer of the elastic roller is thick, if there is a heating means inside the elastic roller like the conventional elastic roller, the warm-up time becomes long, Further, when the process speed is increased, there is a problem that the temperature of the fixing roller does not follow the fixing temperature. Further, when the diameter of the elastic roller is increased, there is a problem that the power consumption of the heating means for heating the fixing roller increases.

  In order to solve such a problem, in Patent Document 1, as a color fixing device, a fixing belt is stretched between a fixing roller and a heating roller, and the fixing roller and the pressure roller are pressed against each other via the fixing belt. A belt fixing device having the above structure is disclosed. In the belt fixing device, the fixing belt with a small heat capacity is heated, so the warm-up time is short, and it is not necessary to incorporate a heat source such as a halogen lamp in the fixing roller. A thick layer can be provided, and a wide nip width can be secured.

  Patent Document 2 discloses a fixing device in which a heating unit is a planar heating element (hereinafter referred to as a “planar heating belt fixing device”) in the belt fixing device. In the sheet heating belt fixing device, the heat capacity of the heating means can be reduced as compared with the heating roller incorporating the heat source disclosed in Patent Document 1. Further, since the planar heating element as a heating means directly generates heat, the thermal responsiveness is improved as compared with the fixing device disclosed in Patent Document 1 that indirectly heats the fixing roller using a heat source inside the fixing roller. Further, the warm-up time can be further shortened and energy saving can be achieved.

JP-A-10-30796 JP 2002-333788 A

  In the fixing device disclosed in Patent Document 2, when a small-size recording medium is continuously passed, the fixing belt suppresses the temperature rise of a portion of the fixing belt where the recording medium does not contact (hereinafter referred to as “non-sheet passing portion”). The sheet heating element is divided in the longitudinal direction, and each divided sheet heating element is energized to generate heat only in the area corresponding to the size of the recording medium in the fixing belt. As a result, since a plurality of temperature sensors and safety sensors, for example, thermostats are required, there is a problem that the configuration of the fixing device is complicated and the fixing device is expensive.

In addition, since the heat capacity of the sheet heating element is small, there is little heat energy that the sheet heating element can hold in the standby state, and when the fixing operation is started continuously from the standby state, the heat supply to the fixing belt cannot catch up and the Shoot occurs and First Copy Time
; FCOT) is required for a long time. Undershooting is a phenomenon in which the temperature of the fixing belt cannot maintain the fixing temperature and falls below the fixing temperature. Specifically, for example, when the fixing temperature is 180 ° C., the temperature of the fixing belt is reduced to the fixing temperature. It is a phenomenon that the temperature falls below 180 ° C permanently or temporarily without being able to follow.

  The object of the present invention is to make the temperature of the fixing belt uniform when fixing to recording media of different sizes, to reduce power consumption, and to shorten the warm-up time and FCOT, thereby increasing the speed. Is provided, and an image forming apparatus including the fixing device is provided.

The present invention includes a fixing roller that is rotatably provided;
A fixing belt formed endlessly, wound around a fixing roller, and rotated as the fixing roller rotates;
A pressure member provided so as to be able to come into pressure contact with the fixing roller via the fixing belt;
Heating means for heating the fixing belt,
The heating means
A plurality of heat generating portions provided in a circumferential direction of the fixing belt so as to be capable of contacting the fixing belt, wherein at least one heat generating portion includes a plurality of heat generating portions provided so as to be detachable from the fixing belt. Members,
Disjunction capable provided across the width direction of advance defined fixing region of the fixing belt, seen including a heat uniformizing member for uniformizing the heat distribution of the fixing belt over the entire width direction of the fixing region,
The heating member includes an arcuate base material that is capable of abutting on the inner peripheral surface portion of the fixing belt, is provided so as to be angularly displaceable around a predetermined angular displacement axis, and has a cross-section formed in an arc shape,
The arcuate base material is provided with at least one heat generating portion and a heat uniformizing member among the plurality of heat generating portions,
The heat uniformizing member is a fixing device that is formed so as to be in contact with the fixing belt in accordance with the angular displacement movement of the arc-shaped base material .

Further, in the present invention, the heat uniformizing member is provided at one end in the circumferential direction of the arc-shaped base material,
At the other end in the circumferential direction of the arc-shaped substrate, another heat generating part is provided,
The other heat generating part is formed so as to come into contact with the fixing belt in accordance with the angular displacement movement of the arcuate base material.

  According to the present invention, the heat uniformizing member includes a heat pipe extending in the width direction of the fixing belt.

Further, the present invention provides a heating part separating / contacting means for separating the heating part from the fixing belt,
A heat equalizing member separating / contacting means for separating the heat uniformizing member from the fixing belt;
The heating unit is configured to change the contact state with respect to at least one of the heating unit and the heat uniformizing member according to the size of the recording medium supplied between the fixing roller and the pressure member. And a control means for controlling the separation / contact means and the heat equalizing member separation / contact means.

Further, the present invention provides a heating part separating / contacting means for separating the heating part from the fixing belt,
A heat equalizing member separating / contacting means for separating the heat uniformizing member from the fixing belt;
Based on the information representing the operating characteristics, the heat generating portion separating / contacting means and the heat uniformizing member separating / connecting means are changed so as to change the state of contacting / disconnecting at least one of the heat generating portion and the heat uniformizing member. Control means for controlling.

The present invention also provides toner image forming means for forming a toner image on a recording medium;
An image forming apparatus comprising: the fixing device of the present invention that fixes a toner image formed by a toner image forming unit to a recording medium.

  According to the present invention, the endless fixing belt is wound around the fixing roller and rotates with the rotation of the fixing roller. When a recording medium on which a toner image is formed is supplied to a portion where the fixing roller and the pressure member are in pressure contact with each other via the fixing belt, the toner is heated by the fixing belt heated by the heating unit, and is added to the fixing roller. The toner image is fixed on the recording medium by the pressure with the pressure member. The heating means includes a heating member having a plurality of heat generating portions and a heat uniformizing member. The plurality of heat generating portions are provided side by side in the circumferential direction of the fixing belt, and at least one heat generating portion is provided so as to be detachable from the fixing belt, so that the heating range in the fixing belt can be changed. Accordingly, when the heat generating portion is brought into contact with the fixing belt, the heat supply amount of the fixing belt can be increased as compared with the case where the heat generating portion is not brought into contact with the fixing belt. Therefore, the temperature of the fixing belt can be quickly raised during warm-up, and temperature followability can be ensured when passing normal size paper, so that a fixing device capable of realizing high speed can be realized. Can do.

In addition, the heat equalizing member is provided so as to be able to be separated from the entire fixing region in the width direction of the fixing belt and uniformizes the heat distribution of the fixing belt over the entire width direction of the fixing region. When brought into contact, the heat of the high temperature portion of the fixing belt can be moved to the low temperature portion to make the temperature uniform. Accordingly, when small-size paper is continuously passed, the heat of the fixing belt portion (hereinafter referred to as “non-sheet passing portion”) where the recording medium does not come in contact with heat of the fixing belt portion (hereinafter referred to as “paper passing portion”) where the recording medium comes into contact. Therefore, the temperature rise of the non-sheet passing portion can be automatically suppressed, the temperature drop of the sheet passing portion can be suppressed, and the power consumption can be reduced. By abutting the heat uniformizing member on the fixing belt, the temperature of the fixing belt can be made uniform when fixing on recording media of different sizes, and the power consumption can be reduced.
The heating member includes an arcuate base material that is capable of contacting the inner peripheral surface portion of the fixing belt and angularly displaceable around the angular displacement axis, and at least one heat generating portion and heat uniformization are provided on the arcuate base material. A member is provided. The heat uniformizing member is formed so as to be in contact with the fixing belt in accordance with the angular displacement movement of the arcuate base material. There is no need to provide the heat generating portion separately from the means for separating and contacting the fixing belt. Therefore, the configuration of the fixing device can be simplified.

  Further, according to the present invention, the heat uniformizing member is provided at one end portion in the circumferential direction of the arc-shaped base material, and the other heat generating portion is provided at the other end portion. Along with the displacement movement, it is formed so as to be in contact with the fixing belt. As a result, the separation and contact of the other heat generating portion and the separation and contact of the heat equalizing member can be performed simultaneously, and the configuration of the fixing device can be further simplified.

  Further, according to the present invention, since the heat equalizing member includes the heat pipe extending in the width direction of the fixing belt, the heat of the non-sheet passing portion can be efficiently moved to the sheet passing portion. Therefore, the heat uniformizing effect of the heat uniformizing member can be improved, the temperature rise of the non-sheet passing portion can be further suppressed automatically, and the temperature drop of the sheet passing portion can be further suppressed. The fixing device can further reduce the electric power.

  According to the present invention, the heat generating portion is separated from the fixing belt by the heat generating portion separating / contacting means, and the heat uniformizing member is separated from / contacted to the fixing belt by the heat uniformizing member separating / contacting means. The heat generating portion separating / contacting means and the heat equalizing member separating / connecting means are controlled by the control means according to the size of the recording medium supplied between the fixing roller and the pressure member. The separation / contact state with respect to at least one of the fixing belts is controlled. As a result, for example, when passing normal size paper, the heat generating portion can be brought into contact with the fixing belt. Accordingly, when the normal size paper is passed, the amount of heat supplied to the fixing belt increases, so that it is possible to ensure temperature followability during continuous paper feeding. Therefore, a high-speed fixing device with reduced power consumption can be obtained.

  According to the present invention, the heat generating portion is separated from the fixing belt by the heat generating portion separating / contacting means, and the heat uniformizing member is separated from / contacted to the fixing belt by the heat uniformizing member separating / contacting means. The heat generating part separating / contacting means and the heat uniformizing member separating / contacting means are connected to and separated from at least one of the heat generating part and the heat uniformizing member based on the information indicating the operation characteristics by the control means. Is controlled to change. Thus, for example, at the time of warm-up, the heat generating portion can be brought into contact with the fixing belt, and the heat uniformizing member can be brought into contact with the fixing belt during standby. Therefore, since the amount of heat supplied to the fixing belt increases during warm-up, the temperature of the fixing belt can be quickly raised to the fixing temperature, and heat is accumulated in the heat equalizing member having a large heat capacity during standby. Undershoot does not occur even when continuous paper is passed immediately after standby, and FCOT (first copy time) can be shortened. Therefore, a faster fixing device can be obtained.

  According to the present invention, the image forming apparatus includes the above-described excellent fixing device of the present invention and a toner image forming unit. Since the fixing device of the present invention has a simplified device configuration and can be reduced in cost, the image forming device having the fixing device of the present invention is configured to simplify the device configuration of the image forming device itself. And cost reduction. In addition, the fixing device of the present invention can quickly increase the temperature of the fixing belt during warm-up, and can ensure the temperature followability when passing a normal size paper, so that high speed can be realized. A high-speed image forming apparatus can be obtained by configuring the image forming apparatus with the fixing device of the present invention.

  The fixing device according to the first embodiment of the present invention fixes an unfixed toner image on a recording medium by applying heat and pressure to the recording medium on which an unfixed toner image is formed. An unfixed toner image is a nonmagnetic one-component developer composed of nonmagnetic toner, a nonmagnetic two-component developer composed of nonmagnetic toner and carrier, or a developer such as a magnetic developer composed of magnetic toner (hereinafter, simply referred to as “nonmagnetic toner”). It may be referred to as “developer”).

  FIG. 1 is a schematic cross-sectional view showing the configuration of the fixing device 15 according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the heating member 156 shown in FIG. 1 as viewed from the section line S148-S148. As shown in FIGS. 1 and 2, the fixing device 15 includes a fixing roller 15 a, a pressure roller 15 b, a fixing belt 113, a heating unit 117, a first thermistor 118, and a second thermistor 119.

  The fixing roller 15a and the pressure roller 15b, which are a pair of fixing members, are pressed against each other with a predetermined load, for example, 216N, via the fixing belt 113. The pressure roller 15a corresponds to a pressure member. When the fixing roller 15a and the pressure roller 15b are in pressure contact with each other, a portion (hereinafter referred to as “fixing nip portion”) 138 in which the fixing roller 15a and the pressure roller 15b are in pressure contact with each other via the fixing belt 113 is interposed therebetween. It is formed.

  The fixing roller 15a is rotatably provided and is rotationally driven in the direction of the arrow 121 by a driving motor which is a driving unit (not shown). The fixing roller 15a rotates the fixing belt 113 in the direction of an arrow 136 with the frictional force between the surface of the fixing roller 15a and the fixing belt 113, and further pressurizes with the frictional force between the surface of the fixing belt 113 and the pressure roller 15b. The roller 15b is rotated in the direction of the arrow 137. Thus, the fixing belt 113 and the pressure roller 15b rotate following the rotation of the fixing roller 15a. Accordingly, the fixing roller 15a and the pressure roller 15b rotate in opposite directions. As a result, the recording medium is nipped and conveyed by the fixing roller 15a and the pressure roller 15b, passes through the fixing nip portion 138, and an unfixed toner image is fixed on the recording medium. When the recording medium passes through the fixing nip 138, the fixing roller 15a contacts the surface of the recording medium on which the toner image is formed via the fixing belt 113, and the pressure roller 15b forms a toner image of the recording medium. It abuts against the surface opposite to the surface being applied.

  The fixing roller 15a is a roll-shaped member having a two-layer structure in which a cylindrical cored bar 153 and an elastic layer 154 are formed in order from the inside. Examples of the material of the core metal 153 include metals such as iron, stainless steel, aluminum, and copper, and alloys thereof. Examples of the material of the elastic layer 154 include rubber materials having heat resistance such as silicone rubber and fluorine rubber. In this embodiment, the fixing roller 15a is configured by using a core metal made of stainless steel having a diameter of 15 mm as a core metal and using a silicon sponge rubber layer having a thickness of 7.5 mm as an elastic layer. The diameter of the fixing roller 15a is 30 mm.

  A heater lamp 120 that heats the pressure roller 15b is provided inside the pressure roller 15b. In another embodiment of the present invention, a heat source such as the heater lamp 120 may not be included in the pressure roller 15b. However, a heat source is provided in the pressure roller 15b and heat from the pressure roller 15b is used for fixing. Thus, fixing can be assisted. In the pressure roller 15b, a control circuit (not shown) supplies power to the heater lamp 120 with a power supply circuit (not shown), whereby the heater lamp 120 emits light and infrared rays are emitted from the heater lamp 120. The inner surface of the pressure roller 15b is heated by absorbing infrared rays from the heater lamp 120, and the entire pressure roller 15b is heated by the transmission of the heat. In the present embodiment, a heater lamp with a rated power of 400 W is used as the heater lamp 200 inside the pressure roller 15b.

The pressure roller 15b is a roll-shaped member having a three-layer structure in which a cylindrical core metal 151, an elastic layer 152, and a release layer 155 are formed in order from the inside. A heater lamp 120 is provided on the radially inner side of the core bar 151. Examples of the material of the core metal 151 include metals such as iron, stainless steel, aluminum, and copper, and alloys thereof. Examples of the material of the elastic layer 152 include heat-resistant rubber materials such as silicone rubber and fluorine rubber. As the material of the release layer 155, PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), polytetrafluoroethylene (
and fluororesins such as polytetrafluoroethylene (PTFE). In this embodiment, the pressure roller 15b uses a cored bar made of iron (STKM) having an inner diameter of 24 mm and a wall thickness of 2 mm as the cored bar 151, a silicon solid rubber layer with a thickness of 3 mm as the elastic layer, and a release layer. As a PFA tube having a thickness of 30 μm. The outer diameter of the pressure roller 15b is 30 mm.

  In this embodiment, the width (hereinafter referred to as “nip width”) of the fixing nip portion 138 formed by the fixing roller 15a and the pressure roller 15b via the fixing belt 113 in the recording medium conveyance direction is 7 mm.

  The fixing belt 113 is heated by the heating member 156 and heats the recording medium on which an unfixed toner image passing through the fixing nip 138 is formed. The fixing belt 113 is suspended by the heating member 115 and the fixing roller 15a, and is wound around the fixing roller 15a at a predetermined angle (hereinafter referred to as “winding angle”) θ.

  The winding angle θ is an angle formed by two line segments respectively connecting two contact points between the surface of the fixing roller 15a and the fixing belt 113 and the axis of the fixing roller 15a. In the present embodiment, the winding angle θ is 185 °.

  The fixing belt 113 is an endless belt-like member having a three-layer structure in which an elastic layer and a release layer are formed on the surface of a hollow cylindrical base material made of a heat-resistant resin such as polyimide or a metal material such as stainless steel and nickel. It is. Examples of the material for the elastic layer include elastomer materials excellent in heat resistance and elasticity, such as silicone rubber. Examples of the material for the release layer on the surface of the elastic layer include synthetic resin materials excellent in heat resistance and releasability, such as Fluorine resins such as PFA and PTFE can be mentioned. When polyimide is used as the base material, the sliding load between the fixing belt and the heating member can be further reduced by internally adding a fluororesin to the polyimide. In the present embodiment, the fixing belt 113 uses a base material made of polyimide having a thickness of 70 μm as a base material, a silicone rubber layer having a thickness of 150 μm as an elastic layer, and a PFA tube having a thickness of 30 μm as a release layer. Configured. The diameter of the fixing belt 113 is 45 mm.

  The heating unit 117 includes a heating member 156 that is a roll-shaped member that contacts the fixing belt 113 and heats the fixing belt 113 to a fixing temperature, and a heat uniformizing member 124. As shown in FIG. 2, the heating member 156 is provided on the body 126 and a heating member body 157 that is a hollow roll-shaped member including a body 126 and two journal parts 127 on both sides of the body 126. A planar heating element 122 and a support 123. The trunk portion 126 has a semicircular arc-like cross-sectional shape having a cutout portion in which the lower half is cut. A skirt portion 139 is attached to the lower portion of the semicircular arc-shaped body portion 126.

  As shown in FIG. 1, the skirt 139 includes a support 123, a heat uniformizing member 124, and an extension 122 a of the planar heating element 122. The support 123 is an aluminum member formed in a hollow quadrangular prism shape with a rectangular cross section, and a heat equalizing member 124 is provided on one side inside the support 123, and the heat equalizing member inside the support 123. An extension 122 a of the planar heating element 122 is provided on the opposite side to 124. The planar heating element 122 includes a heating part 166, and the heating part 166 includes an extension heating part 166 a formed on the extension part 122 a of the planar heating element 122 and a heating part 166 formed on the planar heating element 122. The arc-shaped heat generating portion 166c, which is the remaining portion excluding the extension heat generating portion 166a.

  The heat uniformizing member 124 is made of a metal block having high heat conductivity such as aluminum or copper. In the present embodiment, the heat uniformizing member 124 has a rectangular parallelepiped shape whose longitudinal direction is parallel to the rotation axis of the heating member 156. Two cylindrical heat pipes 125 are built in the heat uniformizing member 124 so as to extend in the longitudinal direction. The number of heat pipes 125 is not limited to two. For example, one or three heat pipes 125 may be incorporated. In another embodiment of the present invention, the heat pipe 125 may not be incorporated.

  As shown in FIG. 2, the heating member 156 has the journal portion 127 inserted into the side frame 140 of the fixing device main body 150 via the bearing 141. The journal portion 127 is inserted into the meandering prevention collar 142. The meander-preventing collar 142 is realized by a ball bearing and has a positional relationship such that the outer ring portion 143 contacts the end portion in the width direction of the fixing belt 113. One journal portion 127 a is provided with a gear chain 144 and is driven to rotate by the rotation of the pulse motor 145. The rotational drive of the gear chain 144 is transmitted to one journal portion 127a, and the heating member 156 is angularly displaced in the circumferential direction. The gear chain 144 and the pulse motor 145 correspond to a heat generating part connecting / disconnecting unit and a heat uniformizing member connecting / disconnecting unit.

  In this embodiment, the diameter of the trunk portion 126 is 28 mm, and the diameter of the journal portion 127 is 20 mm. The heating member main body 157 is made from an aluminum pipe having a thickness of 1 mm. The aluminum holder 157 which is the heating member main body 157 has a roller shape at the end, and has a configuration in which a meandering prevention collar 142 made of a ball bearing is fitted from the radially outer side. The meander-preventing collar 142 comprises a ball bearing having an inner diameter of 20 mm, an outer diameter of 32 mm, and a width of 7 mm.

  The heating member main body 157 that is an arcuate base material is realized by an aluminum holder, for example. In this embodiment, the outer peripheral surface of the aluminum holder 157 that is the heating member main body 157 is coated with fluororesin to which carbon is added, and the fluororesin is internally added to the polyimide that is the base material of the fixing belt 113. Therefore, the friction coefficient between the heating member 156 and the fixing belt 113 is suppressed, and the sliding can be performed smoothly.

  Since the aluminum holder 157 has a roller shape at the end and is fitted with a meandering prevention collar 142 made of a ball bearing, the meandering of the fixing belt 113 can be suppressed. Although the aluminum holder itself does not rotate, the meandering prevention collar 142 is made of a ball bearing and can be rotated independently. Therefore, even if the end of the fixing belt 113 abuts against the meandering prevention collar 142, the outer ring part 143 is Since it does not slide and rotates in synchronization with the fixing belt 113, no load is applied to the end of the fixing belt 113, and cracking of the end of the fixing belt 113 can be prevented.

  FIG. 3 is an enlarged cross-sectional view of the heating member 156 shown in FIG. 1 at sections S146 to S146. As shown in FIG. 3, the planar heating element 122 includes a resistance heating layer 128 and an insulating layer 129. The support 123 includes a base material 130 and a coat layer 131. In the present embodiment, the resistance heating layer 128 is a stainless steel foil having a thickness of 15 μm, the insulating layer 129 is a polyimide layer having a thickness of 30 μm, the base material 130 is an aluminum holder having a thickness of 1 mm, and the coating layer 131 is This is a PTFE coating layer having a thickness of 20 μm. The body 126 of the heating member main body 157 shown in FIG. 1 is configured in the same manner as the support 123, and specifically includes a base material and a coat layer.

  The insulating layer 129 and the resistance heating layer 128 of the planar heating element 122 are formed on the surface portion of the base member 130 and the heating member main body 157 of the support 123 in this order. By forming the base material 130 and the heating member main body 157 of the support 123 from aluminum, the heat generated by the planar heating element 122 is transmitted to the fixing belt 113 through the aluminum holder as the base material 130. By transferring heat through the aluminum holder, it is possible to suppress overheating unevenness due to the shape of the heat generation pattern 147 of the resistance heat generation layer 128. Moreover, since the heat transfer (thermal conductivity) in the longitudinal direction is improved by the aluminum holder, it is possible to suppress the temperature rise of the non-sheet passing portion when small size paper is continuously passed.

  FIG. 4 is a plan view showing the configuration of the resistance heating layer 128 of the planar heating element 122. FIG. 4 corresponds to a plan view of the planar heating element 122 viewed from the resistance heating layer 128 side. The sheet heating element 122 includes a power feeding portion 132 provided at both ends in the axial direction of the heating member main body 157 and a heat generating portion 166 provided in an intermediate portion between both ends in the axial direction of the heating member main body 157. The heat generating part 166 includes an extended part heat generating part 166a formed on the extended part 122a of the planar heat generating element 122 and the remaining part of the heat generating part 166 formed on the planar heat generating element 122 except for the extended part heat generating part 166a. Arc-shaped heat generating portion 166c. The resistance heating layer 128 of the heat generating portion 166 has a heat generating pattern 147 that repeats extending from the power feeding portion 132 formed on both sides of the heat generating portion 166 with a certain width in the axial direction of the heating member main body 157 and turning back. In the present embodiment, the line width of the heat generation pattern 147 is 2.4 mm, the interval between the adjacent heat generation patterns 147 is 2.4 mm, the folding length of the adjacent heat generation patterns 147 is 320 mm, and the parallel heat generation patterns The number of 147 is six. Further, the resistance between the power feeding sections 132 is 10Ω. The power supply unit 132 is connected to an AC power source, and AC 100 V is applied to the heat generating unit 166, so that the heat generating unit 166 generates about 1000 W of thermal energy.

  Returning to FIG. 1, in this embodiment, the outer diameter of the heating member 156, that is, the outer diameter of the body 126 of the heating member main body 157 is smaller than the outer diameter of the fixing roller 15a. In another embodiment of the present invention, the outer diameter of the heating member 156 may be equal to or larger than the outer diameter of the fixing roller 15a, but the outer diameter of the heating member 156 is smaller than the outer diameter of the fixing roller 15a. preferable. By doing so, the winding angle θ of the fixing belt 113 with respect to the fixing roller 15a can be increased, and the contact area between the fixing roller 15a and the fixing belt 113 can be increased, so that the fixing belt 113 by the fixing roller 15a can be increased. The rotational force of can be increased. Further, since the contact area between the fixing belt 113 and the heating member 156 can be reduced, a sliding load caused by rubbing between the fixing belt 113 and the heating member 156 can be reduced. In the present embodiment, the width of the contact portion between the fixing belt 113 and the heating member 156 in the circumferential direction of the fixing belt 113 (hereinafter referred to as “heating nip width”) is 44 mm.

  The first thermistor 118 detects the outer peripheral surface temperature of the fixing belt 113, and the second thermistor 119 detects the outer peripheral surface temperature of the pressure roller 15b. Based on the temperature data detected by the first and second thermistors 118 and 119, respectively, the controller 158 as temperature control means controls the surface temperature of the fixing belt 113 and the pressure roller 15b to a predetermined temperature. The heating power 122, the extension 122a of the sheet heating element 122, and the supply power (energization) to the heater lamp 120 are controlled. In the present embodiment, the first thermistor 118 is a non-contact thermistor, and the second thermistor 119 is a contact thermistor.

Next, the operation of the fixing device 15 of this embodiment and the effect of the present invention will be described.
As an operation of the fixing device 15, a recording medium on which an unfixed toner image is formed at a predetermined fixing speed and copying speed is conveyed to the fixing nip portion, and fixing is performed by heat and pressure. The fixing speed is a so-called process speed. The copying speed is the number of copies per minute. These speeds are not particularly limited, but in the present embodiment, the fixing speed is 220 mm / sec.

  In the present embodiment, the endless fixing belt 113 is wound around the fixing roller 15a and rotates with the rotation of the fixing roller 15a. When a recording medium on which a toner image is formed is supplied to a portion where the fixing roller 15a and the pressure roller 15b are in pressure contact with each other via the fixing belt 113, the toner is heated by the fixing belt 113 heated by the heating unit 117. The toner image is fixed on the recording medium by the pressure of the fixing roller 15a and the pressure roller 15b. The heating means 117 includes a heating member 156 having a plurality of heat generating portions 166c and 166a, and a heat equalizing member 124. The plurality of heat generating portions 166c and 166a are provided side by side in the circumferential direction of the fixing belt 113, and at least one extension portion heat generating portion 166a is provided so as to be detachable from the fixing belt 113. Can be changed. As a result, when the extension portion heat generating portion 166a is brought into contact with the fixing belt 113, the heat supply amount of the fixing belt 113 can be increased as compared with the case where the extension portion heat generating portion 166a is not brought into contact with the fixing belt 113. Therefore, at the time of warm-up, the heating member 156 is rotated by a predetermined angle in the direction of the arrow A shown in FIG. 1, and the temperature of the fixing belt 113 is increased by bringing the extension portion heat generating portion 166a into contact with the fixing belt 113. The heating member 156 is rotated by a predetermined angle in the direction of the arrow A shown in FIG. 1 to pass the normal size paper, and the extension heat generating portion 166a is attached to the fixing belt 113. Since the temperature followability can be ensured by the contact, the fixing device 15 capable of realizing high speed can be realized.

  In the present embodiment, the heat equalizing member 124 is provided so as to be able to be separated from the entire fixing region of the fixing belt 113 in the width direction and uniformizes the heat distribution of the fixing belt 113 over the entire width direction of the fixing region. When the uniformizing member 124 is brought into contact with the fixing belt 113, the heat of the high temperature portion of the fixing belt 113 can be moved to the low temperature portion to make the temperature uniform. Therefore, when continuously passing small-size paper, the heating member 156 is rotated and moved in the direction of the arrow B shown in FIG. The heat of the portion of the fixing belt 113 that does not contact (hereinafter referred to as “non-sheet passing portion”) moves to the portion of the fixing belt 113 that contacts the recording medium (hereinafter referred to as “sheet passing portion”). It is possible to suppress the temperature rise of the paper portion, suppress a decrease in the temperature of the paper passing portion, and to obtain the fixing device 15 with reduced power consumption. By abutting the heat uniformizing member 124 on the fixing belt 113, the temperature of the fixing belt 113 can be made uniform when fixing on recording media of different sizes, and power consumption can be reduced.

  In the present embodiment, the heating member 156 includes an arcuate base material that can be brought into contact with the inner peripheral surface portion of the fixing belt 113 and can be angularly displaced about the angular displacement axis, and the arcuate base material has at least one heat generation. A portion 166a and a heat uniformizing member 124 are provided. Since the heat equalizing member 124 is formed so as to come into contact with and separate from the fixing belt 113 with the angular displacement movement of the arcuate base material, the heat uniformizing member 124 is brought into contact with and separate from the fixing belt 113. This means need not be provided separately from the means for bringing the extension heat generating part 166a into contact with the fixing belt 113. Therefore, the configuration of the fixing device 15 can be simplified.

  In the present embodiment, the heat uniformizing member 124 is provided at one end portion in the circumferential direction of the arc-shaped base material, and another heat generating portion 166a is provided at the other end portion. The extension heat generating portion 166a has an arc-shaped base. Along with the angular displacement movement of the material, it is formed so as to come into contact with the fixing belt 113. As a result, the separation and contact of the other heat generating portion 166a and the separation and contact of the heat equalizing member 124 can be performed simultaneously, and the configuration of the fixing device 15 can be further simplified.

  In the present embodiment, the heat equalizing member 124 incorporates a heat pipe extending in the width direction of the fixing belt 113, so that the heat of the non-sheet passing portion can be efficiently moved to the sheet passing portion. Therefore, the heat homogenizing effect of the heat homogenizing member 124 can be improved, the temperature rise of the non-sheet passing portion can be further suppressed automatically, and the decrease in the temperature of the sheet passing portion can be further suppressed, The fixing device 15 can further reduce power consumption.

  In the present embodiment, the extension heat generating portion 166a is separated from the fixing belt 113 by the gear chain 144 and the pulse motor 145, and the heat equalizing member 124 is separated from the fixing belt 113 by the gear chain 144 and the pulse motor 145. Touched. The gear chain 144 and the pulse motor 145 are controlled by the control unit according to the size of the recording medium supplied between the fixing roller 15a and the pressure roller 15b. Then, control is performed so as to change the separation / contact state with respect to at least one of the fixing belts 113. For example, when passing normal size paper, the heating member 156 is rotated by a predetermined angle in the direction of the arrow A shown in FIG. 1 by the gear chain 144 and the pulse motor 145 to fix the extension heat generating portion 166a. It can be brought into contact with the belt. Therefore, when passing normal size paper, the amount of heat supplied to the fixing belt 113 is increased, so that temperature followability during continuous paper passing can be ensured. Therefore, the high-speed fixing device 15 with reduced power consumption can be obtained.

  In the present embodiment, the extension heat generating portion 166a is separated from the fixing belt 113 by the gear chain 144 and the pulse motor 145, and the heat equalizing member 124 is separated from the fixing belt 113 by the gear chain 144 and the pulse motor 145. Touched. The gear chain 144 and the pulse motor 145 and the gear chain 144 and the pulse motor 145 are at least one of the extension heat generating portion 166a and the heat equalizing member 124 based on the information indicating the operation characteristics by the control means. Control is performed so as to change the state of contact with the fixing belt 113. Thus, for example, at the time of warm-up, the heating member 156 is rotated by a predetermined angle in the direction of arrow A shown in FIG. 1 by the gear chain 144 and the pulse motor 145, and the extension heat generating portion 166 a is applied to the fixing belt 113. During the standby, the heating member 156 is rotated by a predetermined angle in the direction of arrow B in FIG. 1 by the gear chain 144 and the pulse motor 145, and the heat equalizing member 124 is brought into contact with the fixing belt 113. Can be made. Accordingly, since the amount of heat supplied to the fixing belt 113 increases during warm-up, the temperature of the fixing belt 113 can be quickly raised to the fixing temperature, and heat is applied to the heat equalizing member 124 having a large heat capacity during standby. Since the paper is stored, undershoot does not occur even when the paper is continuously fed immediately after standby, and the FCOT (first copy time) can be shortened. Therefore, a faster fixing device 15 can be obtained.

The following describes a constant Chakusochi 135. Constant Chakusochi 135, since the configuration other than the fixing device 15 and the heating means in the first embodiment of the present invention is exactly the same, it will not be described configuration other than heating means.

Figure 5 is a schematic sectional view showing a configuration of a constant Chakusochi 135. FIG. 6 is a schematic cross-sectional view of the heating member 134 shown in FIG. 5 as seen from the cutting plane line S149-S149. As shown in FIG. 5 and FIG. 6, the heating member 134 of the present embodiment is a combination of a first planar heating element 122 having a semicircular cross section and a second planar heating element 122b having a semicircular cross section. It has a cylindrical shape. In the first planar heating element 122, the planar heating element 122 used in the first embodiment includes the extended portion 122a of the planar heating element 122 and the cross section is formed in a semicircular arc shape. The first sheet heating element 122 has the same configuration as the sheet heating element 122 except that the section is formed in a semicircular arc shape including the extension 122a of the sheet heating element 122 used in the first embodiment. It is. The second sheet heating element 122b has the same configuration as the first sheet heating element 122 except for the shape of the resistance heating layer 128. The heating member main body 157b, which is a cylindrical base material, has the same configuration as the heating member main body 157, which is an arc-shaped base material in the first embodiment, except that the shape is cylindrical.

  FIG. 7 is a plan view showing the resistance heating layer 128b of the second planar heating element 122b. The resistance heat generating layer 128b is formed by densely forming the heat generating pattern 147 at the center between both ends in the longitudinal direction of the base material 130, that is, folding back at the center. A portion where the heat generation pattern 147 is folded back is a heat generation portion 166b. The second planar heating element 122 b is formed such that the dimension of the heating part 166 b in the width direction of the fixing belt 133 (hereinafter referred to as “width”) is smaller than the width of the heating part 166 of the first planar heating element 122. In this embodiment, the line width of the heat generation pattern 147 is 4 mm, the interval between the adjacent heat generation patterns 147 is 3 mm, the width of the heat generation part 166b is 220 mm, and the number of parallel heat generation patterns 147 is five. . The resistance between the two power supply units 132 is 14.7Ω. The heating nip width between the heating member 135 and the fixing belt 113 is 44 mm.

  An AC power source (not shown) is connected between the two power supply units 132. In the present embodiment, when AC 100 V is applied to the heat generating portion 166b, thermal energy of about 680 W is generated in the heat generating portion 166b.

In this form state, the fixing belt 113 which is formed in an endless shape is wound around the fixing roller 15a, rotates with the rotation of the fixing roller 15a. When a recording medium on which a toner image is formed is supplied to a portion where the fixing roller 15a and the pressure roller 15b are in pressure contact with each other via the fixing belt 113, the toner is heated by the fixing belt 113 heated by the heating unit 117b. The toner image is fixed on the recording medium by the pressure of the fixing roller 15a and the pressure roller 15b. The heating means 117b includes a heating member 134 having a plurality of heat generating portions 166, 166b. The plurality of heat generating portions 166 and 166b have different dimensions in the width direction of the fixing belt 113 (hereinafter referred to as “width”), and are provided so as to be detachable from the fixing belt 113. As a result, the heating range of the fixing belt 113 can be changed, and the heat generation area of the fixing belt 113 can be changed according to the size of the recording medium. can do. Further, when the temperature sensor and the safety sensor for detecting the temperature of the fixing belt 113 are provided, only one each is required, so that the configuration of the fixing device 135 can be simplified as compared with the case where a plurality of temperature sensors and safety sensors are used. Cost can be reduced.

In this form state, the heating member 134, thereby enabling contact with the inner peripheral surface of the fixing belt 113 includes a cylindrical base member which is provided rotatably about an axis, arranged in the circumferential direction of the cylindrical base material The plurality of heat generating portions 166 and 166b are supported by the cylindrical base material, and are formed so as to come into contact with the fixing belt 113 as the cylindrical base material rotates. As a result, the plurality of heat generating portions 166 and 166b can be easily separated from and brought into contact with the fixing belt 113, so that the configuration of the fixing device 135 can be simplified.

In this form state, the heating unit 166,166b is disjunction the fixing belt 113 by the disjunction means, this disjunction means, the control means is supplied between the fixing roller 15a and the pressure roller 15b Control is performed so as to change the state of contact between the heat generating portions 166 and 166b with respect to the fixing belt 113 in accordance with the size of the recording medium. Thus, for example, when passing normal size paper, the wide heat generating portion 166 can be brought into contact with the fixing belt. Therefore, when passing normal size paper, the amount of heat supplied to the fixing belt 113 is increased, so that temperature followability during continuous paper passing can be ensured. Therefore, a high-speed fixing device 135 with reduced power consumption can be obtained.

In this form state, the heating unit 166,166b is disjunction the fixing belt 113 by the disjunction means, this disjunction means, the control means, based on the information indicating the operating characteristics, the heat generating portion 166, Control is performed so as to change the separation / contact state of the fixing belt 113 at 166b. Thus, for example, at the time of warm-up, the heating member 134 is moved by a predetermined angle in the direction of arrow A shown in FIG. 5 using the gear chain 144 and the pulse motor 145 so that the sheet heating element 122 contacts the fixing belt 113. By rotating and moving, the wide heat generating portion 166 can be brought into contact with the fixing belt 113. Therefore, since the amount of heat supplied to the fixing belt 113 increases during warm-up, the temperature of the fixing belt 113 can be quickly raised to the fixing temperature. Therefore, a faster fixing device 135 can be obtained.

  On the other hand, when passing small-size paper, the heating member 134 is rotated 180 degrees in the direction of the arrow B shown in FIG. 5, and the narrow narrow heat generating portion 166b is brought into contact with the fixing belt. As a result, the heating of the fixing belt in the non-sheet passing portion is suppressed, so that the temperature increase in the non-sheet passing portion can be automatically suppressed.

  FIG. 8 is a schematic cross-sectional view schematically showing a configuration of an image forming apparatus 100 including the fixing device 15 according to an embodiment of the present invention. In the present embodiment, the image forming apparatus 100 is a color multifunction peripheral. The image forming apparatus 100 forms an image on a recording medium based on, for example, image data transmitted from each terminal device on the network. The image forming apparatus 100 includes four visible image forming units pa, pb, pc, pd, an intermediate transfer belt 11, an optical system unit E, a secondary transfer unit 14, a fixing unit 15, and an internal paper feeding unit. 16 and a paper feeding unit 17.

  The four visible image forming units pa, pb, pc, and pd form images corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (B), respectively. The first visible image forming unit pa forms an image using yellow (Y) toner, the second visible image forming unit pb forms an image using magenta (M) toner, and the third The visible image forming unit pc forms an image using cyan (C) toner, and the fourth visible image forming unit pd forms an image using black (B) toner. Hereinafter, when a common configuration of the four visible image forming units pa, pb, pc, and pd is described, the reference symbols a, b, c, and d at the end of each configuration may be omitted.

  The four visible image forming units pa, pb, pc, and pd have substantially the same configuration, and each includes a photosensitive drum 101, a charging unit 103, a developing unit 102, and a primary transfer unit 13. And a cleaning unit 104. The primary transfer unit 13 is disposed via the intermediate transfer belt 11. Each visible image forming unit pa, pb, pc, pd transfers each color toner to the intermediate transfer belt 11 in a multiple manner.

  The photosensitive drum 101 is an image carrier and carries an image to be formed. First, the surface of the photosensitive drum 101 is uniformly charged to a predetermined potential by the charging unit 103. In this embodiment, the charging unit 103 uses a charging roller system in order to uniformly charge the surface of the photosensitive drum 101 and to charge ozone without generating ozone as much as possible. The uniformly charged photoreceptor drum 101 is laser-exposed according to image information of each color by the optical system unit E, and an electrostatic latent image is formed on the surface of the photoreceptor drum 101. The optical system unit E is arranged so that data from the light source 4 reaches the surface of the photosensitive drum 101.

  The electrostatic latent image formed on the surface of the photoconductive drum 101 is visualized with toner of each color by the developing unit 102. The developing unit 102 contains yellow, magenta, cyan, and black toners, respectively. The visualized toner image is transferred to the intermediate transfer belt 11 by applying a bias voltage having a polarity opposite to that of the toner to the intermediate transfer belt by the primary transfer unit 13.

  The intermediate transfer belt 11 is disposed without being bent by the tension roller 11a and the tension roller 11b. A waste toner box 12 is disposed in contact with the tension roller 11b, and a secondary transfer unit 14 is disposed in contact with the tension roller 11a. The toner on the intermediate transfer belt remaining without being transferred by the secondary transfer unit 14 is stored in the waste toner box 12. The cleaning unit 104 removes and collects toner remaining on the surface of the photosensitive drum 101 after the transfer of the toner image formed on the photosensitive drum 101. The transfer of the toner image to the recording medium as described above is repeated four times for four colors.

  The toner image transferred to the intermediate transfer belt 11 is conveyed to the secondary transfer unit 14 and is supplied to a recording medium supplied by the paper feed roller 16a of the internal paper feed unit 16 or the paper feed roller 17a of the manual paper feed unit 17. The toner image is transferred to a recording medium by applying a bias voltage having a polarity opposite to that of the toner. The toner image transferred to the recording medium is conveyed to the fixing device 15. The fixing device 15 applies appropriate heat and pressure to the recording medium to dissolve the toner and fix the toner image on the recording medium. The recording medium on which the image is formed is discharged to the outside of the image forming apparatus 100.

  In the present embodiment, the image forming apparatus 100 includes the above-described excellent fixing device 15 of the present invention and a toner image forming unit. Since the fixing device 15 of the present invention has a simplified device configuration and can be reduced in cost, the image forming device 100 is configured by including the fixing device 15 of the present invention. The device configuration can be simplified and the cost can be reduced. In addition, the fixing device 15 of the present invention can quickly increase the temperature of the fixing belt 113 during warm-up, and can ensure the temperature followability when passing a normal size paper, thereby realizing high speed. The image forming apparatus 100 is configured to include the fixing device 15 of the present invention, whereby the high-speed image forming apparatus 100 can be obtained.

1 is a schematic cross-sectional view illustrating a configuration of a fixing device 15 according to a first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of the heating member 156 shown in FIG. It is an expanded sectional view in section S146-S146 of the heating member 156 shown in FIG. 4 is a plan view showing a configuration of a resistance heating layer 128. FIG. It is a schematic sectional view showing a configuration of a constant Chakusochi 135. FIG. 6 is a schematic cross-sectional view of the heating member 134 shown in FIG. It is a top view which shows the resistance heating layer 128b of the 2nd planar heating element 122b. 1 is a schematic cross-sectional view schematically illustrating a configuration of an image forming apparatus 100 including a fixing device 15 according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 Fixing device 15a Fixing roller 15b Pressure roller 18 1st thermistor 19 2nd thermistor 113 Endless fixing belt 117 Heating means 120 Heater lamp 122 Planar heating element 122a Extension part of planar heating element 123 Support body 124 Heat equalization member 125 Heat pipe 139 Skirt part 156 Heating member

Claims (6)

A fixing roller rotatably provided;
A fixing belt formed endlessly, wound around a fixing roller, and rotated as the fixing roller rotates;
A pressure member provided so as to be able to come into pressure contact with the fixing roller via the fixing belt;
Heating means for heating the fixing belt,
The heating means
A plurality of heat generating portions provided in a circumferential direction of the fixing belt so as to be capable of contacting the fixing belt, wherein at least one heat generating portion includes a plurality of heat generating portions provided so as to be detachable from the fixing belt. Members,
Disjunction capable provided across the width direction of advance defined fixing region of the fixing belt, seen including a heat uniformizing member for uniformizing the heat distribution of the fixing belt over the entire width direction of the fixing region,
The heating member includes an arcuate base material that is capable of abutting on the inner peripheral surface portion of the fixing belt, is provided so as to be angularly displaceable around a predetermined angular displacement axis, and has a cross-section formed in an arc shape,
The arcuate base material is provided with at least one heat generating portion and a heat uniformizing member among the plurality of heat generating portions,
The heat uniformizing member is formed so as to be in contact with the fixing belt in accordance with the angular displacement movement of the arc-shaped base material . The heat uniformizing member is provided at one end in the circumferential direction of the arc-shaped base material,
At the other end in the circumferential direction of the arc-shaped substrate, another heat generating part is provided,
The fixing device according to claim 1 , wherein the other heat generating portion is formed so as to come into contact with the fixing belt in accordance with the angular displacement movement of the arc-shaped base material. Heat equalizing member, a fixing device according to claim 1 or 2, characterized in that a built-in heat pipe extending in the width direction of the fixing belt. A heating part separating / contacting means for separating the heating part from the fixing belt;
A heat equalizing member separating / contacting means for separating the heat uniformizing member from the fixing belt;
The heating unit is configured to change the contact state with respect to at least one of the heating unit and the heat uniformizing member according to the size of the recording medium supplied between the fixing roller and the pressure member. the fixing device according to any one of claims 1-3, characterized in that it comprises a control means for controlling the disjunction means and the heat uniformizing member disjunction means. A heating part separating / contacting means for separating the heating part from the fixing belt;
A heat equalizing member separating / contacting means for separating the heat uniformizing member from the fixing belt;
Based on the information representing the operating characteristics, the heat generating portion separating / contacting means and the heat uniformizing member separating / connecting means are changed so as to change the state of contacting / disconnecting at least one of the heat generating portion and the heat uniformizing member. the fixing device according to any one of claims 1-3, characterized in that it comprises a control means for controlling. Toner image forming means for forming a toner image on a recording medium;
An image forming apparatus, comprising a fixing device according to any one of claims 1 to 5 for fixing the toner image formed by the toner image forming means on the recording medium.

Images