JP5470086B2 - Heat fixing belt, fixing device, and image forming apparatus including the fixing device - Google Patents

Description

  The present invention relates to a heat fixing belt having a heat generating layer including a heat generating resistor that generates heat when energized, a fixing device for fixing a toner image on a recording medium using the heat fixing belt, and an image forming apparatus including the fixing device. About.

  As a fixing device used in an electrophotographic image forming apparatus such as a copying machine or a printer, a heat roller fixing type fixing device is known. The fixing device of the heat roller fixing system includes a pair of rollers (fixing roller and pressure roller) that are in pressure contact with each other, and the roller is heated by a heating unit including a halogen lamp or the like disposed inside or both of the roller pair. After the pair is heated to a predetermined temperature (fixing temperature), a recording medium such as a recording sheet on which an unfixed toner image is formed is fed to the pressure contact portion (fixing nip portion) of the roller pair and passed through the pressure contact portion. Therefore, the toner image is fixed on the recording paper by heat and pressure.

  In a fixing device provided in a color image forming apparatus, it is common to use an elastic roller provided with an elastic layer made of silicon rubber or the like on the surface of the fixing roller. By using an elastic roller as the fixing roller, the surface of the fixing roller is elastically deformed corresponding to the unevenness of the unfixed toner image, and comes into contact so as to cover the toner image surface. It is possible to perform heat fixing on an unfixed toner image satisfactorily. In addition, a color image forming apparatus using an elastic roller as a fixing roller can improve releasability for color toners that are more likely to be offset than monochrome because of the strain relief effect of the elastic layer at the fixing nip.

  By the way, in order to obtain a color image forming apparatus corresponding to high speed, a fixing device provided in the color image forming apparatus needs to be configured so that a fixing nip portion having a wide nip width is formed. Examples of a method for widening the nip width of the fixing nip portion include a method of increasing the thickness of the elastic layer of the fixing roller and a method of increasing the diameter of the fixing roller. However, since the elastic layer of the fixing roller has a very low thermal conductivity, there is a problem that the surface temperature of the fixing roller does not follow the increase in the process speed when there is a heating means inside the fixing roller. On the other hand, when the diameter of the fixing roller is increased, problems such as an increase in warm-up time until the surface temperature of the fixing roller reaches the fixing temperature and an increase in power consumption occur.

  As a fixing device provided in a color image forming apparatus that solves such a problem, Patent Document 1 discloses a fixing device of a belt fixing type. A belt-fixing type fixing device includes a fixing belt suspended between a fixing roller and a heating roller, and a pressure roller disposed so as to face the fixing roller via the fixing belt. The fixing belt is heated by a heat source disposed inside the roller. In the belt-fixing type fixing device, a fixing nip portion is formed at a pressure contact portion where the fixing roller is pressed against the pressure roller via the fixing belt. Such a belt-fixing type fixing device is configured to heat a fixing belt having a small heat capacity, so that the warm-up time until the surface temperature of the fixing belt reaches the fixing temperature can be shortened. In addition, since the belt fixing type fixing device does not require a heating means such as a halogen lamp inside the fixing roller, use a fixing roller provided with a thick low-elastic layer made of sponge rubber or the like. And a fixing nip portion having a wide nip width can be formed.

JP 2003-107938 A

  However, in the belt-fixing type fixing device disclosed in Patent Document 1, the fixing belt is heated by a heat source disposed inside the heating roller, so that the fixing belt is not directly heated but heated from the heat source. Heat is transmitted by the heat transmitted through the roller, resulting in a loss of heat energy. Further, in the belt fixing type fixing device disclosed in Patent Document 1, since a plurality of heat sources corresponding to the size of the recording paper are provided, the heat capacity of the heat source itself increases and the loss of heat energy further increases. End up.

  Accordingly, an object of the present invention is an endless heat-fixing belt used when a toner image carried on a recording medium is heated and fixed, and it is possible to suppress the loss of heat energy. It is to provide a heat fixing belt. Another object of the present invention is a fixing device of a belt fixing system, which has a short warm-up time until a desired fixing temperature is obtained, and can prevent an increase in power consumption, and the fixing device. An image forming apparatus is provided.

The present invention is an endless heat fixing belt that heats and fixes a toner image on a recording medium by contacting the toner image carried on the recording medium,
An insulating base material having electrical insulation and formed in a cylindrical shape;
Including a heating resistor that generates heat when energized, and a heating layer provided on the surface of one side in the thickness direction of the insulating base;
Has releasability against the toner image, formed on the surface of one side in the thickness direction of the heat generating layer, viewed contains a release layer in contact with said toner image,
The heating layer is provided such that both ends in the width direction extend outward from the insulating base material,
An electrode portion for energizing the heat generating layer, the electrode portion provided in contact with a portion extending outward from the insulating base of the heat generating layer,
The electrode part is
A pair of strip-shaped first electrode portions provided over the entire circumferential direction at both ends in the width direction of the heat generating layer;
Each of the pair of first electrode portions includes a plurality of second electrode portions aligned at predetermined intervals along the circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions. A heat-fixing belt comprising two rows of second electrode portions arranged opposite to each other.

The heat fixing belt of the present invention is an endless heat fixing belt that heats and fixes a toner image on a recording medium by contacting the toner image carried on the recording medium,
An insulating base material having electrical insulation and formed in a cylindrical shape;
Including a heating resistor that generates heat when energized, and a heating layer provided on the surface of one side in the thickness direction of the insulating base;
A release layer having a releasability with respect to a toner image, provided on a surface on one side in a thickness direction of the heat generating layer, and a release layer in contact with the toner image;
The heating layer is provided such that both ends in the width direction extend outward from the insulating base material,
A pair of electrode portions for energizing the heat generating layer, wherein a pair of strip-shaped first electrode portions provided in contact with the entire circumferential direction on a portion of the heat generating layer extending outward from the insulating base material. Prepared,
The insulating base material has a through-hole penetrating in the thickness direction over the entire circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions,
The heat-generating layer is a heat-fixing belt formed so as to be exposed from the through-hole to the surface on the other side in the thickness direction of the insulating base material .

  In the heat fixing belt of the present invention, an elastic layer having elasticity is provided between at least one of the insulating base and the heat generating layer and between the heat generating layer and the release layer. It is characterized by being able to.

The present invention also includes a first fixing member;
A support member disposed to face the first fixing member;
A rotatable endless belt member stretched between the first fixing member and the support member, the heat fixing belt having a heat generating layer that generates heat when energized;
A second fixing member disposed opposite to the first fixing member via the heat fixing belt;
A power supply member for supplying power to the heat generating layer of the heat fixing belt;
A power source for applying a voltage to the power supply member;
A switch configured to be capable of switching between electrical conduction and interruption between the power supply member and the power source,
A fixing device that heats and fixes a toner image carried on a recording medium on a recording medium at a fixing nip formed by contact between the heat fixing belt and the second fixing member. is there.

In the fixing device of the present invention, the power supply member includes a first power supply unit provided in contact with the first electrode unit, and a second power supply unit provided in contact with the second electrode unit,
The switch is configured to be capable of switching between electrical conduction and interruption between the first power feeding unit and the power source and between the second power feeding unit and the power source.

In the fixing device of the present invention, the power supply member is provided in contact with the first power supply portion provided in contact with the first electrode portion, and in the second power supply provided in contact with the portion exposed from the through hole in the heat generation layer. And
The switch is configured to be capable of switching between electrical conduction and interruption between the first power feeding unit and the power source and between the second power feeding unit and the power source.

  The fixing device according to the present invention is characterized in that a circumferential length of the second power feeding portion is set to be longer than a circumferential length of the fixing nip portion.

In addition, the fixing device of the present invention includes a control unit that controls a switching operation of the switch.
According to another aspect of the present invention, there is provided an image forming apparatus comprising the fixing device.

  According to the present invention, the heat fixing belt is an endless belt member that heats and fixes a toner image on the recording medium by contacting the toner image carried on the recording medium. The heat fixing belt includes an insulating base material, a heat generating layer, and a release layer. The insulating base material has electrical insulation and is formed in a cylindrical shape. The heat generating layer includes a heat generating resistor that generates heat when energized, and is provided on the surface on one side in the thickness direction of the insulating base material. The release layer has a releasability with respect to the toner image, and is provided on the surface on one side in the thickness direction of the heat generating layer to form a surface in contact with the toner image.

  The heat-fixing belt configured as described above can heat the toner image carried on the recording medium using heat generated by energizing the heat generating layer. For this reason, the heat-fixing belt can heat the toner image contacting the surface of the release layer to a desired fixing temperature without heat supplied from an external heat source, resulting in a loss of heat energy. Can be suppressed.

  According to the invention, the heat-fixing belt includes an electrode portion for energizing the heat generating layer and provided in contact with a portion of the heat generating layer that extends outward from the insulating base material. This electrode part includes a pair of first electrode parts and two rows of second electrode part groups. The pair of first electrode portions are provided in a band shape over the entire circumferential direction at both ends in the width direction of the heat generating layer. The second electrode group of two rows is composed of a plurality of second electrode parts aligned at a predetermined interval along the circumferential direction on the inner side in the width direction with respect to the first electrode part, respectively. Through the width direction.

  In the heat-fixing belt configured as described above, when power is supplied between the pair of first electrode portions, the entire surface of the heat generating layer is energized, and therefore, the entire surface of the heat generating layer generates heat. It becomes an area. On the other hand, when electric power is supplied between some second electrode parts that face each other in the width direction through the insulating base material among the plurality of second electrode parts constituting each second electrode part group, On the surface of the heat generating layer that comes into contact with the second electrode portion to which the first electrode portion is supplied, a rectangular region having the apex at the apex portion on the outer side in the width direction of each second electrode portion arranged oppositely is energized. The rectangular area on the surface of the heat generating layer becomes a heat generating area. In this way, the heat generation area on the surface of the heat generation layer can be changed by a simple control of switching the electrode portion that supplies power.

  Further, according to the present invention, the heat fixing belt is an electrode portion for energizing the heat generating layer, and is provided in contact with a portion extending outward from the insulating base of the heat generating layer over the entire circumferential direction. A pair of strip-shaped first electrode portions is provided. In the heat fixing belt, the insulating base material has a through-hole penetrating in the thickness direction over the entire circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions. In the heat fixing belt, the heat generating layer is formed so as to be exposed from the through hole to the surface on the other side in the thickness direction of the insulating base material.

  In the heat-fixing belt configured as described above, when power is supplied between the pair of first electrode portions, the entire surface of the heat generating layer is energized, and therefore, the entire surface of the heat generating layer generates heat. It becomes an area. On the other hand, when power is supplied from the through hole to the exposed portion of the heat generating layer exposed on the surface of the insulating base, the top end portion on the outer side in the width direction of the exposed portion of the heat generating layer is apex on the surface of the heat generating layer. Therefore, the rectangular region on the surface of the heat generating layer becomes the heat generating region. In this way, the heat generation area on the surface of the heat generation layer can be changed by simple control of switching the portion to which power is supplied.

  According to the invention, the heat-fixing belt is provided with an elastic layer having elasticity between at least one of the insulating base material and the heat generating layer and between the heat generating layer and the release layer. . As a result, the surface of the release layer in contact with the toner image carried on the recording medium is elastically deformed corresponding to the unevenness of the toner image, and the heat fixing belt contacts the toner image so as to cover the toner image. Heat fixing can be performed on the image satisfactorily. Further, the heat fixing belt can improve the peeling performance of the recording medium from the surface of the release layer due to the strain release effect due to the elastic deformation of the elastic layer.

  According to the invention, the fixing device includes a first fixing member, a support member arranged to face the first fixing member, and the invention stretched between the first fixing member and the support member. Such a heat fixing belt, a second fixing member disposed to face the first fixing member via the heat fixing belt, a power supply member for supplying power to the heat generating layer of the heat fixing belt, and a voltage applied to the power supply member And a switch configured to be capable of switching between conduction and interruption of electricity between the power supply member and the power source.

  In the fixing device configured as described above, the heat generation layer generates heat by supplying power from the power supply member to the heat generation layer by connecting the power supply member and the power source with a switch, and heat generated from the heat generation layer is generated. The toner image carried on the recording medium can be heated and fixed on the recording medium at the fixing nip portion formed by contacting the heat fixing belt and the second fixing member. Since the fixing device includes the heat fixing belt according to the present invention that can suppress the loss of heat energy, the warm-up time until a desired fixing temperature is obtained is short, and the power consumption is increased. Can be prevented.

  According to the invention, in the fixing device, the power supply member is provided in contact with the first electrode portion of the heat fixing belt and in contact with the second electrode portion of the heat fixing belt. A power supply unit. In the fixing device, the switch is configured to be capable of switching between electrical conduction and interruption between the first power supply unit and the power source and between the second power supply unit and the power source.

  In the fixing device configured as described above, the switch is brought into conduction between the first power supply unit and the power source, and power is supplied from the first power supply unit to the pair of first electrode units, so that Using the heat generated from the surface, the toner image carried on the recording medium can be heated and fixed on the recording medium. On the other hand, between the second power feeding unit and the power source is made conductive by the switch, and power is supplied between some second electrode units facing each other across the insulating base material among the plurality of second electrode units. Accordingly, the toner image carried on the recording medium can be heated and fixed on the recording medium using heat generated from a part of the surface of the heat generating layer. As described above, the heat generation area on the surface of the heat generation layer can be changed according to the fixing condition by a simple control of switching the power supply unit to which the voltage from the power source is applied. As a result, thermal deterioration of the heat fixing belt can be suppressed, and an increase in power consumption can be prevented.

  According to the invention, in the fixing device, the power supply member is in contact with the first power supply portion provided in contact with the first electrode portion of the heat fixing belt, and the portion exposed from the through hole in the heat generating layer of the heat fixing belt. And a second power feeding unit provided. In the fixing device, the switch is configured to be capable of switching between electrical conduction and interruption between the first power supply unit and the power source and between the second power supply unit and the power source.

  In the fixing device configured as described above, the switch is brought into conduction between the first power supply unit and the power source, and power is supplied from the first power supply unit to the pair of first electrode units, so that Using the heat generated from the surface, the toner image carried on the recording medium can be heated and fixed on the recording medium. On the other hand, from the surface of a part of the heat generating layer, the switch is made conductive between the second power feeding unit and the power source, and power is supplied from the through hole to the exposed portion of the heat generating layer exposed on the surface of the insulating base. Using the generated heat, the toner image carried on the recording medium can be heated and fixed on the recording medium. As described above, the heat generation area on the surface of the heat generation layer can be changed according to the fixing condition by a simple control of switching the power supply unit to which the voltage from the power source is applied. As a result, thermal deterioration of the heat fixing belt can be suppressed, and an increase in power consumption can be prevented.

  According to the invention, in the fixing device, the circumferential length of the second power feeding portion is set to be longer than the circumferential length of the fixing nip portion. As a result, even when a voltage is applied to the second power feeding unit by the power source and a part of the surface of the heat generating layer becomes a heat generating region, the fixing device sets the circumferential length of the heat generating region to the fixing nip. It is possible to make the length longer than the circumferential length of the portion, and to prevent occurrence of offset of the fixed image.

  According to the invention, the fixing device includes control means for controlling the switching operation of the switch. In the fixing device configured as described above, the control unit controls the switching operation of the switch, thereby switching the power supply unit to which the voltage from the power source is applied, and changing the heat generation area on the surface of the heat generation layer according to the fixing conditions. be able to.

  In addition, according to the present invention, the image forming apparatus includes the fixing device according to the present invention that has a short warm-up time until a desired fixing temperature is obtained and can prevent an increase in power consumption. Can be realized.

It is a figure which shows the structure of the heat fixing belt 20 which concerns on one Embodiment of this invention. It is a figure which shows the structure of the heat fixing belt 30 which concerns on other embodiment of this invention. 1 is a diagram illustrating a configuration of a fixing device 15 according to an embodiment of the present invention. FIG. 4 is a diagram showing the arrangement position of the power supply member 156 with respect to the heat fixing belt 20. It is sectional drawing seen from the cut surface line XX of FIG. It is sectional drawing seen from the cut surface line Y1-Y1 of FIG. It is sectional drawing seen from the cut surface line Y2-Y2 of FIG. FIG. 4 is a diagram illustrating a position where a power supply member 156 is disposed with respect to the heat fixing belt 30. It is sectional drawing seen from the cut surface line XX of FIG. It is sectional drawing seen from the cut surface line Y1-Y1 of FIG. It is sectional drawing seen from the cut surface line Y2-Y2 of FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 100 according to an embodiment of the present invention. 2 is a block diagram showing an electrical configuration of the image forming apparatus 100. FIG.

<Heat fixing belt>
FIG. 1 is a diagram illustrating a configuration of a heat fixing belt 20 according to an embodiment of the present invention. FIG. 1A is a view from the inner surface side when the heat fixing belt 20 is developed. Moreover, FIG.1 (b) is sectional drawing seen from the cut surface line XX of Fig.1 (a).

  The heat fixing belt 20 is an endless belt member that heats and fixes a toner image on a recording paper by contacting with a toner image carried on a recording medium made of paper or the like (hereinafter referred to as “recording paper”). is there. The heat fixing belt 20 is a laminate in which at least a heat generating layer 22 and a release layer 24 are laminated on an insulating base material 21 having electrical insulation and formed in a cylindrical shape. In the present embodiment, the heat-fixing belt 20 is a laminated body in which a heat generating layer 22, an elastic layer 23, and a release layer 24 are laminated on an insulating substrate 21, and has an outer diameter of 50 mm as a whole and a width dimension L1. Is formed at 364 mm.

  The insulating base material 21 is formed of a material having both heat resistance and electric insulation, and its thickness T1 is about 50 μm. The material having both heat resistance and electrical insulation is not particularly limited, and examples thereof include a heat resistant polymer material such as polyimide resin.

  The heat generating layer 22 includes a heat generating resistor that generates heat when energized, and is provided on the surface of one side in the thickness direction of the insulating base material 21. Specifically, the heat generating layer 22 is made of conductive silicone rubber, conductive polyimide resin or the like to which a conductive filler such as carbon black or metal particles (for example, nickel, titanium, iron, etc.) is added as a heat generating resistor. Is a layer. The heat generating layer 22 may be formed using the heat generating resistor as a film. In the present embodiment, the heat generating layer 22 is provided so that both ends in the width direction extend outward from the insulating base material 21, and is configured to generate 1200 W of thermal energy when a voltage of 100 V is applied. The sheet resistance is 4.1Ω / □, and the thickness T2 is 20 μm.

  The elastic layer 23 has elasticity and is provided on the surface on one side in the thickness direction of the heat generating layer 22. In the present embodiment, the elastic layer 23 is made of a heat-resistant material such as fluororubber or silicone rubber, and its thickness T3 is 150 μm. The elastic layer 23 may be provided between at least one of the insulating base material 21 and the heat generating layer 22 and between the heat generating layer 22 and the release layer 24. As a result, the surface of the release layer 24 that comes into contact with the toner image carried on the recording paper is elastically deformed corresponding to the unevenness of the toner image, and the heat fixing belt 20 comes into contact with the toner image so as to cover the toner image. The toner image can be heat-fixed satisfactorily. Further, the heat fixing belt 20 can improve the peeling performance of the recording paper from the surface of the release layer 24 due to the strain releasing effect due to the elastic deformation of the elastic layer 23.

  The release layer 24 has releasability with respect to the toner image, and is provided on the surface of one side in the thickness direction of the elastic layer 23. In the heat fixing belt 20, the surface on the one side in the thickness direction of the release layer 24 (hereinafter referred to as “the outer peripheral surface of the release layer 24”) is a surface in contact with the toner image. In the present embodiment, the release layer 24 is made of a fluororesin such as PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) and has a thickness T4 of 30 μm. Since the release layer 24 that forms the surface in contact with the toner image has releasability with respect to the toner image, the occurrence of offset can be prevented.

  As described above, the heat fixing belt 20 having a laminated structure in which at least the heat generating layer 22 and the release layer 24 are laminated on the insulating base material 21 uses heat generated by energizing the heat generating layer 22. The toner image carried on the recording paper can be heated. Therefore, the heat-fixing belt 20 can heat the toner image contacting the outer peripheral surface of the release layer 24 to a desired fixing temperature even when no heat is supplied from an external heat source, and heat energy is lost. Can be suppressed.

  The heating and fixing belt 20 of the present embodiment is an electrode portion for energizing the heat generating layer 22, and includes a second row of second electrodes each including a pair of first electrode portions 25 and a plurality of second electrode portions 26. An electrode portion including an electrode portion group is provided in contact with the surface on the other side in the thickness direction of the heat generating layer 22 (hereinafter referred to as “the inner peripheral surface of the heat generating layer 22”).

  The pair of first electrode portions 25 is provided in a strip shape over the entire circumferential direction at both ends in the width direction of the inner peripheral surface of the heat generating layer 22. In the present embodiment, the pair of first electrode portions 25 is formed of a conductive paste made of silver or the like, and in each first electrode portion 25, the length L2 in the width direction is 10 mm and the thickness T1 is 50 μm.

  The second electrode portion group in two rows is composed of a plurality of second electrode portions 26 aligned at a predetermined interval along the circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions 25. Further, they are arranged to face each other in the width direction with the insulating base material 21 interposed therebetween. In the present embodiment, each of the second electrode portions 26 constituting the second row of second electrode portion groups has the same size and the same shape, and the second row of second rows facing the width direction via the insulating base material 21. The second electrode portions 26 in each row of the two-electrode portion group are arranged such that a straight line connecting the centers is orthogonal to the circumferential direction. Specifically, each of the second electrode portions 26 constituting the second electrode portion group in two rows is formed in a rectangular shape by a conductive paste made of silver or the like, and the separation distance L3 from the first electrode portion 25 is 2 mm. The length L4 in the width direction is 10 mm, the length L5 in the circumferential direction is 10 mm, and the thickness T1 is 50 μm. Further, in each second electrode portion group, 14 second electrode portions 26 are provided aligned in the circumferential direction, and a circumferential interval L6 in each second electrode portion 26 is 1 mm.

  Further, in the heat fixing belt 20, the pair of first electrode portions 25 and the second electrode portions 26 constituting the second electrode portion group in two rows are provided on the width direction end portion side as described above, These are regions other than the regions where the first and second electrode portions 25 and 26 are formed, and the width direction of the other surface in the thickness direction of the insulating base material 21 (hereinafter referred to as “inner peripheral surface of the insulating base material 21”) The central area 20a is an area in contact with a fixing roller 151 and a support member 153 of the fixing device 15 described later.

  In the heat-fixing belt 20 configured as described above, when power is supplied between the pair of first electrode portions 25, the entire surface of the heat generating layer 22 is energized. The entire surface of this becomes a heat generation region. On the other hand, when electric power is supplied between some second electrode parts 26 which face each other in the width direction via the insulating base material 21 among the plurality of second electrode parts 26 constituting each second electrode part group. In the surface of the heat generating layer 22 that is in contact with the second electrode portion 26 to which power is supplied, a rectangular region whose apex is the top end portion on the outer side in the width direction of each of the second electrode portions 26 that are arranged to face each other is energized. Therefore, the rectangular area on the surface of the heat generation layer 22 becomes a heat generation area. In this way, the heat generation region on the surface of the heat generation layer 22 can be changed with a simple control of switching the electrode portion that supplies power.

  FIG. 2 is a diagram showing a configuration of a heat fixing belt 30 according to another embodiment of the present invention. FIG. 2A is a diagram viewed from the inner surface side when the heat fixing belt 30 is developed. FIG. 2B is a cross-sectional view taken along the section line XX in FIG.

  The heat-fixing belt 30 is an endless belt member that heats and fixes a toner image on the recording paper by contacting the toner image carried on the recording paper, like the heat-fixing belt 20 described above. The heat fixing belt 30 is a laminate in which at least a heat generating layer 32 and a release layer 34 are laminated on an insulating base 31 that has an electrical insulation and is formed in a cylindrical shape. In the present embodiment, the heat-fixing belt 30 is a laminated body in which a heat generating layer 32, an elastic layer 33, and a release layer 34 are laminated on an insulating base 31, and as a whole, the outer diameter is 50 mm and the width dimension L1. Is formed at 364 mm.

  The insulating base 31 is a cylindrical member that is configured in the same manner as the insulating base 21 provided in the heat fixing belt 20 and has a thickness T1 of about 50 μm. The heat generating layer 32 is configured in the same manner as the heat generating layer 22 included in the heat fixing belt 20 and is provided on the surface of the insulating base 31 on one side in the thickness direction. When a voltage of 100 V is applied, 1200 W of thermal energy is generated. The sheet resistance is 4.1 Ω / □, and the thickness T2 is 20 μm.

  The elastic layer 33 is configured in the same manner as the elastic layer 23 provided in the heat-fixing belt 20, and is provided on the surface on one side in the thickness direction of the heat generating layer 32, and the thickness T3 is 150 μm. The release layer 34 is configured in the same manner as the elastic layer 23 provided in the heat-fixing belt 20, and is provided on the surface of one side in the thickness direction of the elastic layer 33, and the thickness T4 is 30 μm.

  The heat-fixing belt 30 of the present embodiment is an electrode portion for energizing the heat generating layer 32, and the surface on the other side in the thickness direction of the heat generating layer 32 (hereinafter, “ A pair of belt-like first electrode portions 35 provided in contact with the entire circumferential direction). In the present embodiment, the pair of first electrode portions 35 is formed of a conductive paste made of silver or the like, and in each first electrode portion 35, the length L2 in the width direction is 10 mm and the thickness T1 is 50 μm.

  In the heat fixing belt 30, the insulating base 31 has a band-shaped through hole 31 a that penetrates in the thickness direction over the entire circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions 35. The layer 32 is formed so as to be exposed from the through hole 31a to the surface on the other side in the thickness direction of the insulating base material 31 (hereinafter referred to as “inner peripheral surface of the insulating base material 31”). In the present embodiment, the exposed portion of the heat generating layer 32 exposed from the through hole 31a to the inner peripheral surface of the insulating base 31 has a separation distance L3 from the first electrode portion 35 of 2 mm and a length L4 in the width direction of 10 mm. is there.

  Further, in the heat fixing belt 30, the exposed portions of the pair of first electrode portions 35 and the heat generating layer 32 are provided on the side in the width direction as described above. This is a region other than the region where the exposed part is formed, and the central region 30a in the width direction on the inner peripheral surface of the insulating base 31 is a region in contact with a fixing roller 151 and a support member 153 of the fixing device 15 described later.

  In the heat fixing belt 30 configured as described above, when power is supplied between the pair of first electrode portions 35, the entire surface of the heat generating layer 32 is energized. The entire surface of this becomes a heat generation region. On the other hand, when power is supplied from the through hole 31 a to the exposed portion of the heat generating layer 32 exposed on the inner peripheral surface of the insulating base material 31, the width of the exposed portion of the heat generating layer 32 is outside the width direction on the surface of the heat generating layer 32. The rectangular area having the apex at the top end on the side is energized, and therefore the rectangular area on the surface of the heat generating layer 32 becomes a heat generating area. In this way, the heat generation area on the surface of the heat generation layer 32 can be changed by a simple control of switching the portion that supplies power.

<Fixing device>
FIG. 3 is a diagram illustrating a configuration of the fixing device 15 according to the embodiment of the present invention. The fixing device 15 is a device provided in the image forming apparatus 100 described later, and is a device that heats and presses a toner image carried on the recording paper and fixes it on the recording paper. The fixing device 15 includes any one of the heat fixing belts 20 and 30 of the present embodiment described above. A case where the fixing device 15 includes the heat fixing belt 20 will be described.

  FIG. 4 is a diagram illustrating the arrangement position of the power supply member 156 with respect to the heat fixing belt 20. FIG. 5 is a cross-sectional view taken along the section line XX of FIG. FIG. 6 is a cross-sectional view taken along section line Y1-Y1 in FIG. FIG. 7 is a cross-sectional view taken along the section line Y2-Y2 in FIG.

  The fixing device 15 applies a voltage to the heat fixing belt 20, a fixing roller 151 as a first fixing member, a pressure roller 152 as a second fixing member, a support member 153, a power supply member 156, and a power supply member 156. A power supply 160 to be applied and a switch 159 are provided. In the fixing device 15, the heat fixing belt 20 is stretched between the fixing roller 151 and the support member 153, and the pressure roller 152 is disposed so as to face the fixing roller 151 through the heat fixing belt 20. . The fixing roller 151 and the support member 153 are arranged so as to be substantially parallel in the axial direction of the fixing roller 151. That is, the axis of the fixing roller 151 and the axis of the support member 153 are substantially parallel. As a result, when the heat fixing belt 20 stretched between the fixing roller 151 and the support member 153 slides, the heat fixing belt 20 can be prevented from meandering, and the durability of the heat fixing belt 20 can be maintained high. .

  When the recording paper passes through the fixing nip portion 15a formed by the heat fixing belt 20 and the pressure roller 152 at a predetermined fixing speed and copying speed, the fixing device 15 displays the toner image carried on the recording paper on the recording paper. Fix by heating and pressing. The toner image is formed by a developer (toner) such as a non-magnetic one-component developer (non-magnetic toner), a non-magnetic two-component developer (non-magnetic toner and carrier), and a magnetic developer (magnetic toner). Is done. The fixing speed is a so-called process speed, and the copying speed is the number of copies per minute.

  The fixing roller 151 is opposed to and pressed against the pressure roller 152 via the heat fixing belt 20, and is rotatably provided around the axis. The outer peripheral surface of the fixing roller 151 is in contact with the center region 20 a in the width direction on the inner peripheral surface of the insulating base material 21 of the heat fixing belt 20. The fixing roller 151 rotates following the rotation of the pressure roller 152. The fixing roller 151 has a diameter of 30 mm and has a two-layer structure in which a core metal 151a and an elastic layer 151b are formed in order from the inside. The core metal 151a includes, for example, a metal such as iron, stainless steel, aluminum, or copper. Alternatively, alloys thereof are used. For the elastic layer 151b, a heat-resistant rubber material such as silicon rubber or fluorine rubber is suitable. In the present embodiment, stainless steel having a diameter of 20 mm is used as the core metal 151a, and silicon sponge rubber having a thickness of 5 mm is used as the elastic layer 151b.

  The pressure roller 152 is pressed against the fixing roller 151 via the heat fixing belt 20 to form a fixing nip portion 15a, and is driven to rotate around an axis by a driving motor (driving means). Transport. The pressure roller 152 has a three-layer structure in which a core metal 152a, an elastic layer 152b, and a release layer 152c are formed in this order from the inside. For the core metal 152a, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. In addition, a heat-resistant rubber material such as silicon rubber or fluorine rubber is suitable for the elastic layer 152b, and a fluorine resin such as PFA or PTFE (polytetrafluoroethylene) is suitable for the release layer 152c. The pressure roller 152 has, for example, a diameter of 30 mm, an iron (STKM) pipe with a diameter of 26 mm (thickness 1 mm) on the core metal 152a, a silicon solid rubber with a thickness of 1 mm on the elastic layer 152b, and a thickness on the release layer 152c. A roller made of a 50 μm PFA tube can be used. In this embodiment, the force when the pressure roller 152 is pressed against the fixing roller 151 via the heat fixing belt 20 is about 400 N, and the fixing nip portion 15a formed thereby has a circumferential length of about 400 N. 7 mm.

  The support member 153 is formed in a curved shape (R shape) so as to form a part of a cylindrical body, both ends in the width direction are fixedly supported by the main frame, and the outer peripheral surface thereof is the insulating base material 21 of the heat fixing belt 20. It contacts the central region 20a in the width direction on the inner peripheral surface. Further, the support member 153 is formed of a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof, and in order to ensure good slidability with respect to the heat fixing belt 20, a fluororesin is formed on the outer peripheral surface. A coat layer is provided. In the present embodiment, the support member 153 is made of aluminum, and has a thickness of 1 mm, a curvature radius R of 14 mm, and a heat fixing belt 20 with respect to the heat fixing belt 20 having an outer diameter of 50 mm and the fixing roller 151 having a diameter of 30 mm. The circumferential length of the outer peripheral surface in contact with is set to 44 mm. The support member 153 may have a roller shape that is rotatably provided.

  The power supply member 156 is a member for supplying power to the heat generating layer 22 of the heat fixing belt 20, and a power supply brush, a power supply roller, or a plate-shaped power supply plate can be used. In the present embodiment, as shown in FIG. 4, the power supply member 156 includes a first power supply unit 1562 a that is a plate-shaped power supply plate provided in contact with each of the pair of first electrode units 25 of the heat fixing belt 20. And a second power feeding portion 1562b that is a plate-shaped power feeding plate provided in contact with the second electrode portion 26 constituting the second electrode portion group of the two rows of the heat fixing belt 20, and these first power feeding portions. 1562a and the 2nd electric power feeding part 1562b are supported by the electric power feeding part support body 1561 which consists of heat resistant resin. The power supply member 156 is fixedly provided at a position corresponding to the fixing nip portion 15a or a position near the fixing nip portion 15a in the circumferential direction of the heat fixing belt 20. The power supply member 156 is provided so as not to enter the central region 20 a in the width direction on the inner peripheral surface of the heat fixing belt 20.

  In the present embodiment, the first power feeding unit 1562a and the second power feeding unit 1562b in the power feeding member 156 are formed in a rectangular plate shape by phosphor bronze, and the size thereof is equal to the size of the second electrode unit 26 of the heat fixing belt 20. The same (10 mm × 10 mm).

  Further, as shown in FIG. 5, the power supply member 156 has a pressing member (spring) so that the first power supply portion 1562 a is in close contact with the first electrode portion 25 and the second power supply portion 1562 b is in close contact with the second electrode portion 26. The elastic force is given by the member 158. Further, the fixing device 15 has a heat fixing belt at a position facing the power supply member 156 with the heat fixing belt 20 sandwiched so that both ends in the width direction of the heat fixing belt 20 are not deformed by the elastic force of the pressing member 158. A restricting member 157 is provided along the outer peripheral surface of 20.

  The switch 159 is configured to be able to switch between electrical conduction and interruption between the power supply member 156 and the power supply 160, and as illustrated in FIG. 5, the first terminal 159a connected to the first power supply unit 1562a, and the second A second terminal 159b connected to the power feeding unit 1562b and a third terminal 159c connected to the power source 160 are included. The switch 159 connects the first power supply unit 1562a and the power supply 160 by connecting the first terminal 159a and the third terminal 159c, and connects the second terminal 159b and the third terminal 159c. The second power feeding unit 1562b and the power source 160 are brought into conduction.

  In addition, the fixing device 15 has a first thermistor 155 that detects the temperature of the outer peripheral surface of the heat-fixing belt 20 in the vicinity of the fixing nip portion 15a as a temperature detection unit, and the rotational conveyance direction of the heat-fixing belt 20 from the fixing nip portion 15a. And a second thermistor 154 that detects the temperature of the outer peripheral surface on the upstream side. In addition, the temperature detection position with respect to the heat fixing belt 20 by the first thermistor 155 and the second thermistor 154 is not limited to the above. In the fixing device 15, the switching operation of the switch 159 is performed based on the temperature detection result by the first thermistor 155 and the second thermistor 154, and the switching operation of the switch 159 is a device control unit included in the image forming apparatus 100 described later. 41.

  In the fixing device 15 configured as described above, the heat generation layer 22 generates heat when the power supply member 156 and the power source 160 are brought into conduction by the switch 159 and power is supplied from the power supply member 156 to the heat generation layer 22. The heat generated from the heat generating layer 22 is used to heat the toner image carried on the recording paper on the recording paper at the fixing nip portion 15a formed by the contact between the heat fixing belt 20 and the pressure roller 152. It can be fixed. Since the fixing device 15 includes the heating and fixing belt 20 of the present embodiment that can suppress the loss of heat energy, the warm-up time until a desired fixing temperature is obtained is short, and power consumption is reduced. An increase can be prevented.

  Further, in the fixing device 15, the switch 159 whose switching operation is controlled by the device control unit 41 makes the first power feeding unit 1562 a and the power source 160 conductive, and the first power feeding unit 1562 a to the pair of first electrode units. By supplying electric power between the two, the toner image carried on the recording paper can be heated and fixed on the recording paper using heat generated from the entire surface of the heat generating layer 22.

  On the other hand, the switch 159 whose switching operation is controlled by the device control unit 41 makes the second power feeding unit 1562b and the power source 160 conductive, and sandwiches the insulating base material 21 among the plurality of second electrode units 26. By supplying electric power between a part of the second electrode portions 26 facing each other, heat generated from a part of the surface of the heat generating layer 22 is used to heat the toner image carried on the recording paper to Can be fixed. For example, as illustrated in FIG. 7A, the second power feeding unit 1562 b is in contact with one second electrode unit 26 in each column of the second electrode unit group in two columns with respect to the heating and fixing belt 20 that is rotated and conveyed. In the state, a part of the surface of the heat generating layer 22 generates heat by energization corresponding to the rectangular region extending between the second electrode portions 26 facing each other in the width direction via the insulating base material 21. Further, as shown in FIG. 7B, the second power feeding unit 1562b is in contact with the two second electrode portions 26 in each row of the two rows of the second electrode portion group with respect to the heat-fixing belt 20 that is rotated and conveyed. In the state, a part of the surface of the heat generating layer 22 generates heat by energization corresponding to the rectangular region extending between the two second electrode portions 26 facing each other in the width direction via the insulating base material 21.

  Further, when the second power feeding unit 1562b and the power source 160 are in a conductive state, the power feeding member 156 corresponds to the fixing nip portion 15a in the circumferential direction of the heat fixing belt 20, or the fixing nip portion 15a. Since the heat generating layer 22 is provided in a fixed position in the vicinity, the heat generating layer 22 generates heat using the vicinity of the fixing nip portion 15a as a heat generating region. As a result, heat can be prevented from being dissipated from the region other than the region corresponding to the fixing nip portion 15a on the outer peripheral surface of the heat-fixing belt 20, so that the toner image is efficiently fixed on the recording paper. be able to.

  Here, the control of the switching operation of the switch 159 by the device control means 41 will be described. When the fixing device 15 shifts to a start of operation from a state where it has been stopped for a long time (for example, immediately after the main power is turned on or when the operation is resumed from the sleep mode), the device control means 41 controls the switch 159, The first power feeding unit 1562a and the power source 160 are brought into conduction.

  When the fixing device 15 is stopped for a long period of time and the surface temperature of the heat-fixing belt 20 has been lowered to about room temperature, if a part of the area on the surface of the heat-fixing belt 20 is controlled to generate heat, An extreme temperature difference occurs, and a load is applied due to partial thermal expansion of the heat fixing belt 20, leading to deterioration of the heat fixing belt 20. Further, if the control is performed so that a part of the region on the surface of the heat fixing belt 20 generates heat and the fixing operation is started immediately after the desired fixing temperature is reached, there is a possibility that the fixing failure of the toner image on the recording paper may occur. . In such a case, the first power feeding unit 1562a and the power source 160 may be in a conductive state so that the entire surface of the heat generating layer 22 becomes a heat generating region.

  For example, when the desired fixing temperature is 170 ° C., the device control means 41 switches the switch 159 until the temperature detection results by the first thermistor 155 and the second thermistor 154 reach a predetermined standby temperature (for example, 165 ° C.). Is controlled to continue the conduction state between the first power feeding unit 1562a and the power source 160, and shift to the standby state when the standby temperature is reached.

  When a print start signal is input in the standby state, the apparatus control unit 41 causes the entire surface of the heat generating layer 22 to remain until the temperature detection result by the first thermistor 155 and the second thermistor 154 reaches the fixing temperature (170 ° C.). The switch 159 is controlled so that the first heat supply unit 1562a and the power source 160 are in a conductive state so that the heat generation region is obtained.

  When the temperature detection result by the first thermistor 155 and the second thermistor 154 reaches the fixing temperature (170 ° C.), the apparatus control means 41 causes the partial surface of the heat generating layer 22 (the surface corresponding to the vicinity of the fixing nip portion 15a) to generate heat. The switch 159 is controlled so that the second power feeding unit 1562b and the power source 160 are in a conductive state so as to be a region. In this way, the fixing operation based on the print start signal is started in a state in which a part of the surface of the heat generating layer 22 is controlled to be a heat generating region.

  During the fixing operation, when the temperature detection result by the second thermistor 154 becomes equal to or lower than a predetermined first threshold temperature (for example, 150 ° C.), the device control means 41 causes the entire surface of the heat generating layer 22 to become a heat generating region. In addition, the switch 159 is controlled to bring the first power feeding unit 1562a and the power source 160 into a conductive state. When the temperature detection result by the second thermistor 154 becomes equal to or higher than a predetermined second threshold temperature (for example, 160 ° C.), the device control means 41 causes the partial surface of the heat generating layer 22 to become a heat generating region. Then, the switch 159 is controlled to bring the second power feeding unit 1562b and the power source 160 into a conductive state.

  When the fixing operation is completed, the apparatus control unit 41 controls the switch 159 so that the temperature detection result by the first thermistor 155 and the second thermistor 154 becomes the standby temperature, so that the connection between the first power feeding unit 1562a and the power supply 160 is performed. Is switched to a standby state.

  As described above, the heat generation on the surface of the heat generating layer 22 is performed according to the fixing condition by simple control of switching the power supply unit to which the voltage from the power supply 160 is applied between the first power supply unit 1562a and the second power supply unit 1562b. The area can be changed. Thereby, thermal deterioration of the heat fixing belt 20 can be suppressed and an increase in power consumption can be prevented.

  Further, in the fixing device 15, the circumferential length of the second power feeding unit 1562b is set to be longer than the circumferential length of the fixing nip 15a. Specifically, as described above, the circumferential length of the fixing nip portion 15a is set to 7 mm, whereas the circumferential length of the second power feeding portion 1562b is set to 10 mm. . Accordingly, in the fixing device 15, even when a voltage is applied to the second power feeding unit 1562 b by the power supply 160 and a part of the surface of the heat generating layer 22 becomes a heat generating region, the length of the heat generating region in the circumferential direction is increased. Can be made longer than the circumferential length of the fixing nip portion 15a, and the occurrence of low-temperature offset in the fixed image can be prevented.

Further, in the fixing device 15, 2.4 W / cm ² of thermal energy can be obtained per unit area of the heat generation region in the heat generation layer 22 by applying a voltage of 100 V from the power supply 160, so that the heat fixing belt 20 is 220 mm. Even if it is assumed that the sheet is rotated and conveyed at a peripheral speed of / sec and A4 size recording paper is passed through the fixing nip portion 15a at a speed of 40 sheets per minute, a temperature tracking of 170 ° C. is sufficiently possible. . In the conventional fixing device configured to indirectly heat the fixing belt with a halogen lamp or the like, the heat energy required to sufficiently follow the temperature of 170 ° C. is about 600 W, and the surface of the fixing belt It is about 1.2 W / cm ² when converted into thermal energy per unit area.

  Further, in the fixing device 15, since the heat fixing belt 20 has sufficient temperature followability as described above, it is not necessary to provide a plurality of external heat sources unlike the conventional fixing device, and the device configuration is simplified. As well as space saving and cost reduction.

  Next, the case where the fixing device 15 includes the heat fixing belt 30 will be described with reference to FIGS. FIG. 8 is a diagram illustrating the arrangement position of the power supply member 156 with respect to the heat fixing belt 30. FIG. 9 is a cross-sectional view taken along the section line XX of FIG. FIG. 10 is a cross-sectional view taken along the section line Y1-Y1 of FIG. FIG. 11 is a cross-sectional view taken along the section line Y2-Y2 of FIG.

  When the fixing device 15 includes the heat fixing belt 30, the first power supply unit 1562 a of the power supply member 156 is provided in contact with the first electrode unit 35 of the heat fixing belt 30, and the second power supply unit 1562 b is used as the heat fixing belt. It is provided in contact with the exposed portion exposed from the through hole 31a in the 30 heat generating layers 32. The switch 159 conducts electricity between the first power feeding unit 1562a and the power source 160 and between the second power feeding unit 1562b and the power source 160, as in the case where the fixing device 15 includes the heat fixing belt 20. And it is configured to be switchable. The switching operation of the switch 159 is controlled by the device control means 41 as described above based on the temperature detection result by the first thermistor 155 and the second thermistor 154.

  In the fixing device 15 including the heat fixing belt 30, the switch 159 whose switching operation is controlled by the device control unit 41 is brought into conduction between the first power supply unit 1562 a and the power source 160, and the pair of power supplies from the first power supply unit 1562 a. By supplying electric power between the first electrode portions 35, heat generated from the entire surface of the heat generating layer 32 can be used to heat and fix the toner image carried on the recording paper on the recording paper.

  On the other hand, the switch 159 whose switching operation is controlled by the device control means 41 brings the second power feeding unit 1562b and the power source 160 into a conductive state and is exposed to the inner peripheral surface of the insulating base 31 from the through hole 31a. By supplying electric power to the exposed portion 32, the toner image carried on the recording paper can be heated and fixed on the recording paper using heat generated from a part of the surface of the heat generating layer 32. When the second power supply unit 1562b and the power supply 160 are in a conductive state, the power supply member 156 corresponds to the fixing nip portion 15a in the circumferential direction of the heat-fixing belt 30 or in the vicinity of the fixing nip portion 15a. Therefore, the heat generation layer 32 generates heat using the vicinity of the fixing nip portion 15a as a heat generation region. As a result, heat can be prevented from being dissipated from the region other than the region corresponding to the fixing nip portion 15a on the outer peripheral surface of the heat-fixing belt 30, so that the toner image is efficiently fixed on the recording paper. be able to.

  As described above, even when the fixing device 15 includes the heat fixing belt 30, simple control of switching the power supply unit to which the voltage from the power supply 160 is applied between the first power supply unit 1562 a and the second power supply unit 1562 b. Thus, the heat generation area on the surface of the heat generation layer 32 can be changed according to the fixing conditions. As a result, thermal deterioration of the heat fixing belt 30 can be suppressed and an increase in power consumption can be prevented.

  Even when the fixing device 15 includes the heat fixing belt 30, the circumferential length of the second power feeding unit 1562b is set to be longer than the circumferential length of the fixing nip 15a. Specifically, the circumferential length of the fixing nip portion 15a is set to 7 mm, while the circumferential length of the second power feeding portion 1562b is set to 10 mm. Thus, in the fixing device 15, even when a voltage is applied to the second power feeding unit 1562 b by the power supply 160 and a part of the surface of the heat generating layer 32 becomes a heat generating region, the length of the heat generating region in the circumferential direction is increased. Can be made longer than the circumferential length of the fixing nip portion 15a, and the occurrence of low-temperature offset in the fixed image can be prevented.

Even when the fixing device 15 includes the heat fixing belt 30, it is possible to obtain 2.4 W / cm ² of thermal energy per unit area of the heat generating region in the heat generating layer 32 by applying a voltage of 100 V by the power source 160. Therefore, for example, it is assumed that the heating and fixing belt 30 is rotated and conveyed at a peripheral speed of 220 mm / second, and A4 size recording paper is passed through the fixing nip portion 15a at a speed of 40 sheets per minute. Temperature tracking at 170 ° C. is sufficiently possible.

<Image forming apparatus>
FIG. 12 is a diagram showing a configuration of the image forming apparatus 100 according to the embodiment of the present invention. FIG. 13 is a block diagram showing an electrical configuration of the image forming apparatus 100. The image forming apparatus 100 is an apparatus that forms multicolor and single color images on recording paper based on image data of a read original document or image data transmitted via a network or the like. The image forming apparatus 100 includes the above-described fixing device 15 of the present embodiment.

  The image forming apparatus 100 includes an exposure unit 10, a photosensitive drum 101 (101a to 101d), a developing unit 102 (102a to 102d), a charging unit 103 (103a to 103d), a cleaning unit 104 (104a to 104d), and an intermediate transfer belt. 11, a primary transfer unit 13 (13a to 13d), a secondary transfer unit 14, a fixing device 15, paper transport paths P1, P2, and P3, an internal paper feed unit 16, a manual paper feed unit 17, and a paper discharge unit 18. Yes.

  The image forming apparatus 100 corresponds to the hues of four colors of cyan (C), magenta (M), and yellow (Y), which are three subtractive primary colors obtained by color separation of black (K) and a color image. Using the image data, image formation is performed in the image forming units pa to pd corresponding to each hue. Each of the image forming units pa to pd has the same configuration. For example, the black (K) image forming unit pa includes a photosensitive drum 101a, a developing unit 102a, a charging unit 103a, a primary transfer unit 13a, a cleaning unit 104a, and the like. Consists of The image forming portions pa to pd are arranged in a line in the moving direction (sub-scanning direction) of the intermediate transfer belt 11.

  The charging unit 103 is a roller contact type charger that uniformly charges the surface of the photosensitive drum 101 to a predetermined potential. Instead of the charging unit 103, a contact type charger using a charging brush or a non-contact type charger using a charging wire may be used.

  The exposure unit 10 includes a semiconductor laser (not shown), a polygon mirror 4, a first reflection mirror, a second reflection mirror 8, and the like, and includes black (K), cyan (C), magenta (M), and yellow (Y). Each of the photosensitive drums 101a to 101d is irradiated with a light beam such as a laser beam modulated by the image data of each hue. Each of the photosensitive drums 101a to 101d forms an electrostatic latent image based on image data of each hue of black (K), cyan (C), magenta (M), and yellow (Y).

  The developing unit 102 supplies toner as a developer to the surface of the photosensitive drum 101 on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. Each of the developing units 102a to 102d contains toner of each hue of black (K), cyan (C), magenta (M), and yellow (Y), and is formed on each of the photosensitive drums 101a to 101d. The electrostatic latent image of each hue is visualized into a toner image of each hue. The cleaning unit 104 removes and collects toner remaining on the surface of the photosensitive drum 101 after development and image transfer.

  The intermediate transfer belt 11 is disposed above the photosensitive drum 101, and is stretched between the driving roller 11a and the driven roller 11b to form a loop-shaped moving path. The outer peripheral surface of the intermediate transfer belt 11 faces the photosensitive drum 101d, the photosensitive drum 101c, the photosensitive drum 101b, and the photosensitive drum 101a in this order. Primary transfer units 13a to 13d are arranged at positions facing the respective photosensitive drums 101a to 101d with the intermediate transfer belt 11 interposed therebetween. Each of the positions where the intermediate transfer belt 11 faces the photosensitive drums 101a to 101d is a primary transfer position. The intermediate transfer belt 11 is formed of a film having a thickness of about 100 to 150 μm.

  In the primary transfer units 13a to 13d, a primary transfer bias having a polarity opposite to the charging polarity of the toner is controlled at a constant voltage in order to transfer the toner image carried on the surface of the photosensitive drums 101a to 101d onto the intermediate transfer belt 11. Applied. As a result, the toner images of the respective colors formed on the photosensitive drums 101a to 101d are sequentially transferred onto the outer peripheral surface of the intermediate transfer belt 11, and a full-color toner image is formed on the outer peripheral surface of the intermediate transfer belt 11. .

  However, when image data of only a part of the hues of yellow (Y), magenta (M), cyan (C), and black (K) is input, input is performed among the four photosensitive drums 101a to 101d. The electrostatic latent image and the toner image are formed only on a part of the photosensitive drums 101 corresponding to the hue of the image data. For example, when forming a monochrome image, an electrostatic latent image and a toner image are formed only on the photosensitive drum 101a corresponding to the black hue, and only the black toner image is transferred to the outer peripheral surface of the intermediate transfer belt 11. Is done.

  Each of the primary transfer units 13a to 13d is configured in a roller shape in which the surface of a shaft whose base is a metal such as stainless steel is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). A high voltage is uniformly applied to the intermediate transfer belt 11 by the material.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 11 at each primary transfer position is conveyed to a secondary transfer position that is a position facing the secondary transfer unit 14 by the rotation of the intermediate transfer belt 11. The secondary transfer unit 14 is formed in a roller shape, and at the time of image formation, the inner peripheral surface is in pressure contact with the outer peripheral surface of the intermediate transfer belt 11 contacting the peripheral surface of the driving roller 11a with a predetermined nip pressure. . When the recording paper fed from the internal paper feeding unit 16 or the manual paper feeding unit 17 passes between the secondary transfer unit 14 and the intermediate transfer belt 11, the secondary transfer unit 14 is charged with the toner charging polarity. Is applied with a high voltage of reverse polarity. As a result, the toner image is transferred from the outer peripheral surface of the intermediate transfer belt 11 to the surface of the recording paper.

  Of the toner adhering to the intermediate transfer belt 11 from the photosensitive drum 101, the toner remaining on the intermediate transfer belt 11 without being transferred onto the recording paper is used for the transfer cleaning unit in order to prevent color mixing in the next process. 12 is collected.

  The recording paper onto which the toner image has been transferred is guided to the fixing device 15 of the present embodiment described above, and passes through the fixing nip and is heated and pressurized. As a result, the toner image is firmly fixed on the surface of the recording paper. The recording paper on which the toner image is fixed is discharged onto the paper discharge unit 18 by the paper discharge roller 18a.

  In the image forming apparatus 100, the recording paper stored in the internal paper feeding unit 16 is transferred to the paper discharge unit 18 between the secondary transfer unit 14 and the intermediate transfer belt 11 and via the fixing device 15. A paper transport path P1 extending in a substantially vertical direction for feeding is provided. A pickup roller 16a that feeds the recording sheets in the internal paper feeding unit 16 one by one into the sheet conveyance path P1 and a conveyance roller 16b that conveys the fed recording sheets upward are conveyed to the sheet conveyance path P1. A registration roller 19 that guides the recording paper between the secondary transfer unit 14 and the intermediate transfer belt 11 at a predetermined timing and a paper discharge roller 18 a that discharges the recording paper to the paper discharge unit 18 are disposed.

  Further, inside the image forming apparatus 100, a paper conveyance path P2 in which a pickup roller 17a and a conveyance roller 16b are arranged is formed between the manual paper feeding unit 17 and the registration roller 19. Further, a paper transport path P3 is formed between the paper discharge roller 18a and the upstream side of the registration roller 19 in the paper transport path P1.

  The paper discharge roller 18a is rotatable in both forward and reverse directions, and is used to form a second side image when forming a single-sided image for forming an image on one side of the recording paper and for forming a double-sided image for forming an image on both sides of the recording paper. At the time of formation, the recording paper is driven in the forward rotation direction and discharged to the paper discharge unit 18. On the other hand, when the first side image is formed in the double-sided image formation, the paper discharge roller 18a is driven in the forward direction until the rear end of the paper passes through the fixing device 15, and then the rear end of the recording paper is sandwiched. Then, the recording paper is driven in the reverse direction to guide the recording paper into the paper conveyance path P3. As a result, the recording paper on which the image is formed only on one side at the time of double-sided image formation is guided to the paper conveyance path P1 with the front and back sides and the front and rear ends reversed.

  The registration roller 19 feeds the recording paper fed from the internal paper feeding unit 16 or the manual paper feeding unit 17 or conveyed via the paper conveyance path P3 at a timing synchronized with the rotation of the intermediate transfer belt 11. Guided between the next transfer unit 14 and the intermediate transfer belt 11. For this reason, the registration roller 19 stops rotating when the operation of the photosensitive drum 101 and the intermediate transfer belt 11 is started, and the recording paper fed or conveyed prior to the rotation of the intermediate transfer belt 11 is registered at the front end. The movement in the paper transport path P1 is stopped in a state where it is in contact with the roller 19. Thereafter, the registration roller 19 is positioned at the position where the secondary transfer unit 14 and the intermediate transfer belt 11 are in pressure contact with each other, and the front end portion of the recording paper and the front end portion of the toner image formed on the intermediate transfer belt 11 face each other. To start rotation.

  At the time of full color image formation in which image formation is performed in all of the image forming portions pa to pd, the primary transfer units 13a to 13d press the intermediate transfer belt 11 against all of the photosensitive drums 101a to 101d. On the other hand, during monochrome image formation in which image formation is performed only in the image forming portion pa, only the primary transfer unit 13a is brought into pressure contact with the intermediate transfer belt 11 against the photosensitive drum 101a.

  As illustrated in FIG. 2, the image forming apparatus 100 includes an apparatus control unit 41, a storage unit 42, and a calculation unit 43. The apparatus control unit 41 controls the image forming operation in the image forming apparatus 100 as a whole, and also functions as a fixing control unit that controls the fixing operation of the fixing device 15 including the switching operation of the switch 159 provided in the fixing device 15. I also serve.

  In the storage means 42, a print command via an operation panel (display unit 44, input unit 45) disposed on the upper surface of the image forming apparatus 100, detection results from various sensors disposed at various locations inside the image forming apparatus 100, and the like. Image information input from an external device via the USB / LAN 46, various setting values and data tables for controlling the operation of each unit in the image forming apparatus 100, and programs for executing various controls are stored. It is possible. As the storage means 42, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus 100 can be used, and examples thereof include a computer and a digital camera.

  The computing means 43 takes out various data (printing commands, detection results, image information, etc.) stored in the storage means 42 and programs for performing various controls, and performs various detections and / or determinations. The device control means 41 sends a control signal to the corresponding unit in accordance with various determination results, calculation results, etc. in the calculation means 43, and performs operation control.

The device control means 41 and the calculation means 43 are, for example, a central processing unit (CPU, Central
A processing circuit realized by a microcomputer, a microprocessor, or the like provided with a processing unit.

  The image forming apparatus 100 is a multifunction device including, for example, a scanner, a printer, and peripheral devices. The image forming apparatus 100 reads a document image 47, converts the read document image into an appropriate electrical signal, and generates image data. The image processing unit 48 visualizes the generated image data using toner, and forms the image on the recording paper. The image forming unit p described above, and peripherals that control peripheral devices such as finishers and sorters that are post-processing devices A device control unit 49 is provided.

  The control of the fixing operation of the fixing device 15 including the switching operation of the switch 159 by the device control means 41 is as described above.

  The image forming apparatus 100 configured as described above includes the fixing device 15 according to the present invention, which has a short warm-up time until a desired fixing temperature is obtained and can prevent an increase in power consumption. , Energy saving can be realized.

DESCRIPTION OF SYMBOLS 15 Fixing device 20,30 Heating fixing belt 21,31 Insulating base material 31a Through-hole 22,32 Heat generating layer 23,33 Elastic layer 24,34 Release layer 25,35 First electrode part 26 Second electrode part 151 Fixing roller 152 Pressure roller 153 Support member 156 Power supply member 157 Restriction member 158 Press member 159 Switch 160 Power supply 1561 Power supply unit support 1562a First power supply unit 1562b Second power supply unit

Claims (11)

An endless heat fixing belt that heats and fixes a toner image on a recording medium by contacting the toner image carried on the recording medium,
An insulating base material having electrical insulation and formed in a cylindrical shape;
Including a heating resistor that generates heat when energized, and a heating layer provided on the surface of one side in the thickness direction of the insulating base;
Has releasability against the toner image, formed on the surface of one side in the thickness direction of the heat generating layer, viewed contains a release layer in contact with said toner image,
The heating layer is provided such that both ends in the width direction extend outward from the insulating base material,
An electrode portion for energizing the heat generating layer, the electrode portion provided in contact with a portion extending outward from the insulating base of the heat generating layer,
The electrode part is
A pair of strip-shaped first electrode portions provided over the entire circumferential direction at both ends in the width direction of the heat generating layer;
Each of the pair of first electrode portions includes a plurality of second electrode portions aligned at predetermined intervals along the circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions. A heat-fixing belt comprising two rows of second electrode portions arranged opposite to each other . An endless heat fixing belt that heats and fixes a toner image on a recording medium by contacting the toner image carried on the recording medium,
An insulating base material having electrical insulation and formed in a cylindrical shape;
Including a heating resistor that generates heat when energized, and a heating layer provided on the surface of one side in the thickness direction of the insulating base;
Has releasability against the toner image, formed on the surface of one side in the thickness direction of the heat generating layer, viewed contains a release layer in contact with said toner image,
The heating layer is provided such that both ends in the width direction extend outward from the insulating base material,
A pair of electrode portions for energizing the heat generating layer, wherein a pair of strip-shaped first electrode portions provided in contact with the entire circumferential direction on a portion of the heat generating layer extending outward from the insulating base material. Prepared,
The insulating base material has a through-hole penetrating in the thickness direction over the entire circumferential direction on the inner side in the width direction with respect to each of the pair of first electrode portions,
The heat-fixing belt , wherein the heat-generating layer is formed so as to be exposed from the through-hole to the surface on the other side in the thickness direction of the insulating base material .   2. An elastic layer having elasticity is provided between at least one of the insulating base and the heat generating layer and between the heat generating layer and the release layer. The heat fixing belt described in 1. 3. An elastic layer having elasticity is provided between at least one of the insulating base and the heat generating layer and between the heat generating layer and the release layer. The heat fixing belt described in 1. A first fixing member;
A support member disposed to face the first fixing member;
A heating endless belt member stretched between the first fixing member and the support member, wherein the heat fixing belt according to claim 1 or 3 ,
A second fixing member disposed opposite to the first fixing member via the heat fixing belt;
A power supply member for supplying power to the heat generating layer of the heat fixing belt;
A power source for applying a voltage to the power supply member;
A switch configured to be capable of switching between electrical conduction and interruption between the power supply member and the power source,
A fixing device that heats and fixes a toner image carried on a recording medium on a recording medium at a fixing nip formed by contact between the heat fixing belt and the second fixing member. A first fixing member;
A support member disposed to face the first fixing member;
A heat-fixing belt according to claim 2 or 4, wherein the heat-fixing belt is a rotatable endless belt member stretched between the first fixing member and the support member.
A second fixing member disposed opposite to the first fixing member via the heat fixing belt;
A power supply member for supplying power to the heat generating layer of the heat fixing belt;
A power source for applying a voltage to the power supply member;
A switch configured to be capable of switching between electrical conduction and interruption between the power supply member and the power source,
A fixing device that heats and fixes a toner image carried on a recording medium on a recording medium at a fixing nip formed by contact between the heat fixing belt and the second fixing member. The power supply member includes a first power supply unit provided in contact with the first electrode unit, and a second power supply unit provided in contact with the second electrode unit,
6. The switch is configured to be capable of switching between electrical conduction and interruption between the first power feeding unit and the power source and between the second power feeding unit and the power source. The fixing device according to 1. The power supply member includes a first power supply portion provided in contact with the first electrode portion, and a second power supply portion provided in contact with a portion exposed from the through hole in the heat generation layer,
The switch between the first feeding unit power, and claim 6, characterized in that it is configured to be able to switch between conduction and interruption of electric between the second power supply unit and the power supply The fixing device according to 1. The circumferential length of the second feed section, the fixing device according to claim 7 or 8, characterized in that it is set to be longer than the circumferential length of the fixing nip portion. The fixing device according to any one of claims 5-9, characterized in that it comprises a control means for controlling the switching operation of the switch. An image forming apparatus comprising: a fixing device according to any one of claims 5-10.

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