JP6914622B2 - Image forming device and image heating device - Google Patents

Description

The present invention relates to an image forming apparatus such as a copier or a printer using an electrophotographic method or an electrostatic recording method. The present invention also relates to an image heating device such as a fixing device mounted on an image forming device and a gloss imparting device for improving the glossiness of a toner image by reheating a toner image fixed on a recording material.

An image formed on a recording material in a fixing device used in an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) such as a copier or a printer, or an image heating device such as a gloss imparting apparatus in response to a request for power saving. A method of selectively heating a portion has been proposed (Patent Document 1). In this type of heater, heating regions divided into a plurality of heating regions are set in a direction orthogonal to the paper passing direction of the recording material (hereinafter referred to as a longitudinal direction), and a plurality of heating elements for heating each heating region are provided in the longitudinal direction. It is provided. Then, based on the image information of the image formed in each heating region, the image portion is selectively heated by the corresponding heating element. Further, if the heating conditions are adjusted according to the image information and a method for reducing power consumption (Patent Document 2) is used in combination, further power saving can be achieved. Further, it is possible to further reduce power consumption by applying the heating condition correction according to the heat history of the image heating device for each heating region.

Japanese Unexamined Patent Publication No. 6-95540 Japanese Unexamined Patent Publication No. 2013-41118

If the energization control of each heating element is performed under the optimum heating conditions for the image of each heating region by using the methods described in Patent Document 1 and Patent Document 2, the energization control of each heating element is performed as compared with the case where the image portion is not selectively heated. Power saving can be achieved. However, in each heating region, if heating is continued according to the image formed in the heating region, there is a difference in the degree of warming (hereinafter referred to as the amount of heat storage) of the portion corresponding to each heating region of the image heating device. Occurs. If the heating conditions of each heating region are set without considering the amount of heat storage, proper heat supply to the unfixed toner image on the recording material may not be performed, and image defects may occur due to this. It is also not preferable from the viewpoint of power saving. In order to deal with this, it is conceivable to predict the amount of heat storage in each heating region from the heat history of each heating region and correct the heating conditions in each heating region according to the amount of heat storage.

However, the amount of heat stored in one heating region is not determined only by the heat history of the heating region, but is also affected by the heat propagating from the adjacent heating region, that is, the heat history of the adjacent heating region. .. Therefore, the predicted heat storage amount for each heating region may differ significantly from the actual heat storage amount, and there is a possibility that sufficient prediction accuracy cannot always be obtained.

An object of the present invention is to provide a technique capable of more accurately predicting the amount of heat stored in each heating region and obtaining a further power saving effect.

In order to achieve the above object, the image heating device of the present invention is used.
The first rotating body and
A second rotating body that comes into contact with the outer peripheral surface of the first rotating body and that forms a nip portion between the first rotating body and the second rotating body.
A heater in which a plurality of heat generating blocks are arranged in a direction orthogonal to both the transport direction of the recording material and the thickness direction of the recording material.
A control unit that sets the heating conditions for each of the plurality of heat generation blocks for each heat generation block, and the heating conditions for the heat generation block when heating the image unit on the first recording material and the heating conditions on the first recording material. It has a control unit that sets the heating conditions of the heat generating block to be different when heating the non-image part of the above.
The heater is arranged in the internal space of the first rotating body.
An image heating device that heats an image formed on a recording material by passing the recording material through the nip portion.
Among the regions of the nip portion, the region of the nip portion corresponding to the region of the first rotating body heated by the first heat generation block among the plurality of heat generation blocks is the first heating region and the region of the nip portion. Among the plurality of heat generation blocks, the region of the nip portion corresponding to the region of the first rotating body heated by the second heat generation block adjacent to the first heat generation block is defined as the second heating region.
Wherein, the first of the image portion on the recording material, according to the distance in the previous end or et after Tanma the first image portion to be heated by said first heating zone, the first calculating a first quantity of thermal storage in the heating region, the distance in the first of the image portion on the recording material, a second image of the previous edge if et after Tanma heated by the second heating region The second heat storage amount in the second heating region is calculated according to the above.
When the second recording material is conveyed to the nip portion after the first recording material, the heating conditions of the first heat generation block are set according to the first heat storage amount and the second heat storage amount. It is characterized by setting.

According to the present invention, the amount of heat stored in each heating region can be predicted more accurately, and a further power saving effect can be obtained.

Sectional drawing of image forming apparatus which concerns on Example of this invention Sectional drawing of image heating apparatus of Example 1 Diagram of heater configuration of Example 1 Heater control circuit diagram of Example 1 Explanatory drawing of heating regions A _{1 to} A _{7 Acquisition flow of maximum value D MAX} (i) of toner amount conversion value D of Example 1 Relationship diagram of a heating temperature FT _i and the _{D MAX} Example 1 (i) Explanatory drawing of TC, LC, WUC, INC, PC, RMC, DC of Example 1. Relationship diagram of region heat storage amount HRV of Example 1 and correction value of control target temperature TGT Image heating unit PR _i , non-image heating unit PP TGT determination flow Explanatory drawing of image pattern example in Example 1 Illustration of the value of _{D MAX} (i) and FT _i of the heating areas Explanatory drawing of image pattern example in Example 1 _{Relationship diagram of count value CT i} and correction value VA of the heat storage counter of Comparative Example 1-2 Schematic diagram of transition between HRV of Example 1 and CT of Comparative Example 1-2 during continuous printing The figure which shows the comparative experiment result of Example 1 and Comparative Example Explanatory drawing of image pattern example in Example 2 Explanatory drawing of TC, LC, WUC, INC, PC, RMC, DC of Example 2. Calculation flow of heat storage count value CT _{i [n]} in heating region A _{i of Example 2} The figure which shows the comparative experiment result of Example 2 and Example 1.

Hereinafter, embodiments for carrying out the present invention will be described in detail exemplarily based on examples with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. That is, it is not intended to limit the scope of the present invention to the following embodiments.

[Example 1]
1. 1. Configuration of Image Forming Device FIG. 1 is a configuration diagram of an electrophotographic image forming apparatus according to an embodiment of the present invention. Examples of the image forming apparatus to which the present invention can be applied include a copying machine and a printer using an electrophotographic method and an electrostatic recording method, and here, a case where the present invention is applied to a laser printer will be described.

The image forming apparatus 100 includes a video controller 120 and a control unit 113. The video controller 120 receives and processes image information and print instructions transmitted from an external device such as a personal computer as an acquisition unit for acquiring image information formed on the recording material. The control unit 113 is connected to the video controller 120 and controls each unit constituting the image forming apparatus 100 in response to an instruction from the video controller 120. When the video controller 120 receives a print instruction from an external device, image formation is executed by the following operations.

The image forming apparatus 100 feeds the recording material P by the feeding roller 102 and conveys it toward the intermediate transfer body 103. The photosensitive drum 104 is rotationally driven in a counterclockwise direction at a predetermined speed by the power of a drive motor (not shown), and is uniformly charged by the primary charger 105 in the rotational process. The laser beam modulated corresponding to the image signal is output from the laser beam scanner 106, and the photosensitive drum 104 is selectively scanned and exposed to form an electrostatic latent image. Reference numeral 107 denotes a developer, which attaches powder toner, which is a developer, to an electrostatic latent image and visualizes it as a toner image (developer image). The toner image formed on the photosensitive drum 104 is primarily transferred onto the intermediate transfer body 103 that rotates in contact with the photosensitive drum 104.

Here, the photosensitive drum 104, the primary charger 105, the laser beam scanner 106, and the developer 107 are arranged with four colors of cyan (C), magenta (M), yellow (Y), and black (K), respectively. There is. Toner images for four colors are sequentially superimposed and transferred on the intermediate transfer body 103 in the same procedure. The toner image transferred on the intermediate transfer body 103 is secondarily transferred onto the recording material P by the transfer bias applied to the transfer roller 108 in the secondary transfer portion formed by the intermediate transfer body 103 and the transfer roller 108. NS. In the above configuration, the configuration related to the formation of the toner image on the recording material P corresponds to the image forming portion in the present invention. After that, the fixing device 200 as an image heating device heats and pressurizes the recording material P, so that the toner image is fixed to the recording material and discharged to the outside of the machine as an image forming product.

The control unit 113 manages the transport status of the recording material P by the transport sensor 114, the resist sensor 115, the pre-fixing sensor 116, and the fixing paper discharge sensor 117 on the transport path of the recording material P. In addition, the control unit 113 has a storage unit that stores the temperature control program and the temperature control table of the fixing device 200. The control circuit 400 as a heater driving means connected to the commercial AC power supply 401 supplies electric power to the fixing device 200.

2. Configuration of Fixing Device (Fixing Section) FIG. 2 is a schematic cross-sectional view of the fixing device 200 of this embodiment. The fixing device 200 includes a fixing film 202, a heater 300 that contacts the inner surface of the fixing film 202, and a pressure roller 208 that forms a fixing nip portion N together with the heater 300 via the fixing film 202.

The fixing film 202 is a flexible multi-layer heat-resistant film formed in a tubular shape, and is made of a heat-resistant resin such as polyimide having a thickness of about 50 to 100 μm or a metal such as stainless steel having a thickness of about 20 to 50 μm as a base layer. Can be used as. Further, a release layer is provided on the surface of the fixing film 202 to prevent adhesion of toner and ensure separability from the recording material P. The release layer is a heat-resistant resin having excellent releasability, such as a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) having a thickness of about 10 to 50 μm. Further, in the fixing film used for the apparatus for forming a color image, in order to improve the image quality, as an elastic layer between the base layer and the release layer, the thickness is about 100 to 400 μm and the thermal conductivity is 0.2 to 3.0 W. Heat-resistant rubber such as silicone rubber of about / m · K may be provided. In this embodiment, from the viewpoint of thermal responsiveness, image quality, durability, etc., a polyimide having a thickness of 60 μm as a base layer, a silicone rubber having a thickness of 300 μm as an elastic layer and a thermal conductivity of 1.6 W / m · K, and a thickness as a release layer. A 30 μm PFA is used.

The pressure roller 208 has a core metal 209 made of a material such as iron or aluminum, and an elastic layer 210 made of a material such as silicone rubber. The heater 300 is held by the heater holding member 201 made of heat-resistant resin and heats the fixing film 202. The heater holding member 201 also has a guide function for guiding the rotation of the fixing film 202. The metal stay 204 receives a pressing force from an urging member or the like (not shown) to urge the heater holding member 201 toward the pressurizing roller 208. The pressure roller 208 receives power from the motor 30 and rotates in the direction of arrow R1. As the pressure roller 208 rotates, the fixing film 202 is driven to rotate in the direction of arrow R2. The unfixed toner image on the recording material P is fixed by applying heat to the fixing film 202 while sandwiching and transporting the recording material P in the fixing nip portion N.

The heater 300 is a heater in which a heating resistor as a heating element provided on a ceramic substrate 305 generates heat when energized. The heater 300 has a surface protective layer 308 that contacts the inner surface of the fixing film 202 and a side opposite to the side (hereinafter, referred to as a sliding surface side) on which the surface protective layer 308 of the substrate 305 is provided (hereinafter, the back surface side). It has a surface protective layer 307 provided in (referred to as). An electrode for feeding power (here, electrode E4 is shown as a representative) is provided on the back surface side of the heater 300. C4 is an electric contact that contacts the electrode E4, and power is supplied to the electrode from the electric contact. Details of the heater 300 will be described later. Further, safety elements 212 such as a thermo switch and a temperature fuse that operate due to abnormal heat generation of the heater 300 to cut off the electric power supplied to the heater 300 are arranged facing the back surface side of the heater 300.

3. 3. Configuration of Heater FIG. 3 is a schematic view showing the configuration of the heater 300 according to the first embodiment of the present invention.
FIG. 3A is a cross-sectional view of the heater in the vicinity of the transport reference position X shown in FIG. 3B. The transport reference position X is defined as a reference position when transporting the recording material P. In the image forming apparatus of this embodiment, the recording material is transported so that the central portion in the width direction orthogonal to the transport direction of the recording material P passes through the transport reference position X. The heater 300 generally has two layers (back surface layers 1 and 2) on one surface (back surface) of the substrate 305 and two layers (sliding surface layers 1 and 2) on the other surface (sliding surface). Each has a formed five-layer structure.

The heater 300 has a first conductor 301 (301a, 301b) provided along the longitudinal direction of the heater 300 on the surface of the substrate 305 on the back surface layer side. Further, the heater 300 is provided on the substrate 305 at different positions in the lateral direction (direction orthogonal to the longitudinal direction) of the first conductor 301 and the heater 300 along the longitudinal direction of the heater 300. It has a conductor 303 (303-4 in the vicinity of the transport reference position X). The first conductor 301 is separated into a conductor 301a arranged on the upstream side in the transport direction of the recording material P and a conductor 301b arranged on the downstream side. Further, the heater 300 is provided between the first conductor 301 and the second conductor 303, and generates heat by the electric power supplied through the first conductor 301 and the second conductor 303. It has a resistor 302.

In this embodiment, the heat-generating resistors 302 are the heat-generating resistor 302a (302a-4 near the transport reference position X) arranged on the upstream side of the recording material P in the transport direction and the heat-generating resistor 302b arranged on the downstream side. It is separated into (302b-4 near the transport reference position X). Further, on the back surface layer 2 of the heater 300, an insulating (glass in this embodiment) surface protective layer 307 covering the heat generating resistor 302, the first conductor 301, and the second conductor 303 is provided as an electrode portion. (E4 near the transport reference position X) is avoided.

FIG. 3B shows a plan view of each layer of the heater 300. The back surface layer 1 of the heater 300 is provided with a plurality of heat generating blocks including a pair of a first conductor 301, a second conductor 303, and a heat generating resistor 302 in the longitudinal direction of the heater 300. The heater 300 of this embodiment has a total of seven heat generating blocks HB1 to HB7 in the longitudinal direction of the heater 300. The heat generation region is from the left end of the heat generation block HB1 in the figure to the right end of the heat generation block HB7 in the figure, and the length thereof is 220 mm. In this example, the longitudinal widths of the heat generating blocks are all the same (not necessarily all the same longitudinal widths).

The heat generation blocks HB1 to HB7 are each composed of heat generation resistors 302a-1 to 302a-7 and heat generation resistors 302b-1 to 302b-7 formed symmetrically in the lateral direction of the heater 300. The first conductor 301 is composed of a conductor 301a connected to a heat generating resistor (302a-1 to 302a-7) and a conductor 301b connected to a heat generating resistor (302b-1 to 302b-7). There is. Similarly, the second conductor 303 is divided into seven conductors 303-1 to 303-7 in order to correspond to the seven heat generating blocks HB1 to HB7.

The electrodes E1 to E7, E8-1 and E8-2 are connected to the electrical contacts C1 to C7, C8-1 and C8-2. The electrodes E1 to E7 are electrodes for supplying electric power to the heat generating blocks HB1 to HB7 via the conductors 303-1 to 303-7, respectively. The electrodes E8-1 and E8-2 are common electrodes for supplying electric power to the seven heat generating blocks HB1 to HB7 via the conductors 301a and 301b. In this embodiment, the electrodes E8-1 and E8-2 are provided at both ends in the longitudinal direction, but for example, a configuration in which only the electrode E8-1 is provided on one side (that is, a configuration in which the electrode E8-2 is not provided) may be used. , Electrode E8-1 and electrode 8-2 may be divided into two in the recording material transport direction, respectively.

The surface protective layer 307 of the back surface layer 2 of the heater 300 is formed so that the electrodes E1 to E7, E8-1 and E8-2 are exposed. As a result, the electric contacts C1 to C7, C8-1 and C8-2 can be connected to each electrode from the back surface layer side of the heater 300, and the heater 300 can supply power from the back surface layer side. It is composed. Further, the electric power supplied to at least one heat generating block of the heat generating blocks and the electric power supplied to the other heat generating blocks can be controlled independently.

By providing the electrodes on the back surface of the heater 300, it is not necessary to wire the substrate 305 with a conductive pattern, so that the width of the substrate 305 in the lateral direction can be shortened. Therefore, it is possible to obtain the effect of reducing the material cost of the substrate 305 and shortening the start-up time required for the temperature rise of the heater 300 due to the reduction of the heat capacity of the substrate 305. The electrodes E1 to E7 are provided in the region where the heat generating resistor is provided in the longitudinal direction of the substrate.

In this embodiment, as the heat generating resistor 302, a material having a characteristic that the resistance value increases as the temperature rises (hereinafter, referred to as PTC characteristic) is used. By using a material with PTC characteristics for the heat generation resistor, the resistance value of the heat generation resistor in the non-passing part becomes higher than that in the paper passing part during the fixing process of small size paper, and current does not flow easily. The effect is obtained. As a result, the effect of suppressing the temperature rise of the non-passing paper portion can be enhanced. However, the material used for the heat generating resistor 302 is not limited to the one having PTC characteristics, and the material having the characteristic that the resistance value decreases as the temperature rises (hereinafter referred to as NTC characteristics) and the temperature change. On the other hand, it is also possible to use a material having a property that the resistance value does not change.

Thermistors T1-1 to T1-4 are on the sliding surface layer 1 on the sliding surface (the surface in contact with the fixing film) side of the heater 300 in order to detect the temperature of each of the heat generating blocks HB1 to HB7 of the heater 300. , And thermistors T2-5 to T2-7 are installed. Thermistors T1-1 to T1-4 and thermistors T2-5 to T2-7 are thinly formed materials having PTC characteristics or NTC characteristics (NTC characteristics in this embodiment) on a substrate. Since all of the heat generating blocks HB1 to HB7 have thermistors, the temperature of all the heat generating blocks can be detected by detecting the resistance value of the thermistors.

In order to energize the four thermistors T1-1 to T1-4, conductors ET1-1 to ET1-4 for detecting the resistance value of the thermistors and a common conductor EG1 of the thermistors are formed. The thermistor block TB1 is formed by the combination of these conductors and thermistors T1-1 to T1-4. Similarly, in order to energize the three thermistors T2-5 to T2-7, a conductor ET2-5 to ET2-7 for detecting the resistance value of the thermistor and a common conductor EG2 of the thermistor are formed. The thermistor block TB2 is formed by the combination of these conductors and thermistors T2-5 to T2-7.

The effect of using the thermistor block TB1 will be described. First, by forming the common conductor EG1 of the thermistor, it is possible to reduce the cost of forming the wiring of the conductive pattern as compared with the case of connecting and wiring the conductors to the thermistors T1-1 to T1-4, respectively. .. Further, since it is not necessary to perform wiring by the conductive pattern on the substrate 305, the width in the lateral direction of the substrate 305 can be shortened. Therefore, it is possible to obtain the effect of reducing the material cost of the substrate 305 and shortening the start-up time required for the temperature rise of the heater 300 due to the reduction of the heat capacity of the substrate 305. Since the effect of using the thermistor block TB2 is the same as that of the thermistor block TB1, the description thereof will be omitted.

In order to shorten the width of the substrate 305 in the lateral direction, the configurations of the heat generating blocks HB1 to HB7 described in the surface layer 1 of FIG. 3A and the thermistor block described in the sliding surface layer 1 of FIG. A method of using TB1 to TB2 in combination is effective.

The sliding surface layer 2 on the sliding surface (surface in contact with the fixing film) side of the heater 300 has a slidable surface protective layer 308 (glass in this embodiment). The surface protective layer 308 is a heater for connecting electrical contacts to the thermistor resistance values ET1-1 to ET1-4, ET2-5 to ET2-7, and the thermistor common conductors EG1 and EG2. It is formed so as to avoid both ends of the 300. The surface protective layer 308 is provided on the surface of the heater 300 facing the film 202, excluding both ends, at least in a region where the heater 300 slides on the film 202.

As shown in FIG. 3C, electrodes E1, E2, E3, E4, E5, E6, E7, E8-1, and E8-2 are formed on the surface of the heater holding member 201 facing the heater 300, and electricity is provided. Holes are provided for connecting contacts C1 to C7, C8-1, and C8-2. The safety element 212, electrical contacts C1 to C7, C8-1, and C8-2 described above are provided between the stay 204 and the heater holding member 201. The electrical contacts C1 to C7, C8-1 and C8-2 that come into contact with the electrodes E1 to E7, E8-1 and E8-2 are electrically connected to the electrode portion of the heater by a method such as spring urging or welding. It is connected to the. Each electric contact is connected to the control circuit 400 of the heater 300, which will be described later, via a conductive material such as a cable or a thin metal plate provided between the stay 204 and the heater holding member 201. Further, the electric contacts provided in the conductors ET1-1 to ET1-4 and ET2-5 to ET2-7 for detecting the resistance value of the thermistor and the common conductors EG1 and EG2 of the thermistor are also combined with the control circuit 400 described later. It is connected.

4. Configuration of Heater Control Circuit FIG. 4 is a circuit diagram of the control circuit 400 of the heater 300 of the first embodiment. Reference numeral 401 denotes a commercial AC power supply connected to the image forming apparatus 100. The power control of the heater 300 is performed by energizing / shutting off the triacs 411 to 417. The triacs 411 to 417 operate according to the FUSER1 to FUSER7 signals from the CPU 420, respectively. The drive circuits of the triacs 411 to 417 are omitted. The control circuit 400 of the heater 300 has a circuit configuration capable of independently controlling the seven heat generating blocks HB1 to HB7 by the seven triacs 411 to 417. The zero-cross detection unit 421 is a circuit that detects the zero-cross of the AC power supply 401, and outputs a ZEROX signal to the CPU 420. The ZEROX signal is used for detecting the timing of phase control and wave number control of the triacs 411 to 417.

The temperature detection method of the heater 300 will be described. The temperature detected by the thermistors T1-1 to T1-4 of the thermistor block TB1 is the partial pressure between the thermistors T1-1 to T1-4 and the resistors 451 to 454, which is a Th1-1 to Th1-4 signal. Is detected by the CPU 420. Similarly, the temperature detected by the thermistor T2-5 to T2-7 of the thermistor block TB2 is such that the partial pressure between the thermistor T2-5 to T2-7 and the resistor 465-467 is Th2-5 to Th2. It is detected by the CPU 420 as a -7 signal. In the internal processing of the CPU 420, the power to be supplied is calculated based on the difference between the control target temperature of each heat generation block and the current detection temperature of the thermistor. For example, the power to be supplied is calculated by PI control. Further, it is converted into a control level of a phase angle (phase control) corresponding to the supplied electric power and a wave number (wave number control), and the triacs 411 to 417 are controlled according to the control conditions.

The relay 430 and the relay 440 are used as means for shutting off power to the heater 300 when the heater 300 is overheated due to a failure or the like. The circuit operation of the relay 430 and the relay 440 will be described. When the RLON signal is in the High state, the transistor 433 is in the ON state, the secondary coil of the relay 430 is energized from the power supply voltage Vcc, and the primary contact of the relay 430 is in the ON state. When the RLON signal is in the Low state, the transistor 433 is turned off, the current flowing from the power supply voltage Vcc to the secondary coil of the relay 430 is cut off, and the primary contact of the relay 430 is turned off. Similarly, when the RLON signal is in the High state, the transistor 443 is in the ON state, the secondary coil of the relay 440 is energized from the power supply voltage Vcc, and the primary contact of the relay 440 is in the ON state. When the RLON signal is in the Low state, the transistor 443 is turned off, the current flowing from the power supply voltage Vcc to the secondary coil of the relay 440 is cut off, and the primary contact of the relay 440 is turned off. The resistor 434 and the resistor 444 are current limiting resistors.

The operation of the safety circuit using the relay 430 and the relay 440 will be described. When any one of the detection temperatures by the thermistors Th1-1 to Th1-4 exceeds the predetermined value set respectively, the comparison unit 431 operates the latch unit 432, and the latch unit 432 latches the RLOFF1 signal in the Low state. do. When the RLOFF1 signal is in the Low state, even if the CPU 420 sets the RLON signal in the High state, the transistor 433 is kept in the OFF state, so that the relay 430 can be kept in the OFF state (safe state). The latch portion 432 outputs the RLOFF1 signal in the open state in the non-latch state. Similarly, when any one of the detection temperatures by the thermistors Th2-5 to Th2-7 exceeds a predetermined value set respectively, the comparison unit 441 operates the latch unit 442, and the latch unit 442 lowers the RLOFF2 signal. Latch in the state. When the RLOFF2 signal is in the Low state, even if the CPU 420 sets the RLON signal in the High state, the transistor 443 is kept in the OFF state, so that the relay 440 can be kept in the OFF state (safe state). Similarly, the latch portion 442 outputs the RLOFF2 signal in the open state in the non-latch state.

5. Outline of the heater control method The image forming apparatus of this embodiment is applied to each of the seven heat generating blocks HB1 to HB7 of the heater 300 according to the image data (image information) sent from an external device (not shown) such as a host computer. The configuration is such that the power supply is optimally controlled to selectively heat the image unit. In the apparatus of this example, the power supply to each of the heat generation blocks HB1 to HB7 is determined by the control target temperature as one of the heating conditions set in each heat generation block HB1 to HB7 (hereinafter referred to as the control target temperature TGT). Notation). The CPU 420 generates heat so that the detection temperature of the thermistors T1-1 to T2-7 corresponding to the heat generation blocks HB1 to HB7 maintains the control target temperature TGT set for each heat generation block HB1 to HB7. Control the power supplied to the block.

The control target temperature TGT set for each of the heat generation blocks HB1 to HB7 is determined by the image formed on the recording material and the heat storage state of each heat generation block. In this embodiment, first, from the image data (image information), the planned value of the control target temperature TGT (hereinafter referred to as the planned heating temperature FT) is used so that the image having a large amount of toner is heated at a higher temperature. ) Is decided. Further, the planned heating temperature FT is corrected according to the amount of heat stored in the fixing device in the portion corresponding to the image position, and the control target temperature TGT is determined. The first embodiment has a configuration in which the amount of heat stored in the fixing device is predicted from the heating history and heat dissipation history of the fixing device.

_{FIG. 5 is a diagram showing seven heating regions A 1 to} A 7 that can be heated by the heater 300, and is displayed in comparison with the size of LETTER size paper. Heating area _A 1 to A ₇ is a region where heat generation block HB1~HB7 can respectively heated by heating blocks HB1 heating region _{A 1} is heated, a configuration in which the heating region _{A 7} is heated by the heating block HB7 ing. In the seven heat generation blocks HB1 to HB7, the amount of heat generated by each heat generation block is individually controlled by individually controlling the amount of electricity supplied to the heat generation resistor in each block. The total length of the heating regions A _{1 to} A ₇ is 220 mm, and each region is evenly divided into seven (L = 31.4 mm).

Here, in one heating area A _{i (i} = 1~7) of the seven heating zones, when the image is formed only on a part of the recording material conveyance direction, the image heating an area where the image is present It is written as part PR _i (i = 1 to 7). The image heating unit PR _i (i = 1 to 7) is heated at the control target temperature TGT described above. In Example 1, when the image that will be formed in one heating area A _{i (i} = 1~7) there are a plurality of the recording material conveyance direction, wherein all of the plurality of images in the recording material conveyance direction and a minimum of The region is defined as the image heating unit PR _i (i = 1 to 7). Further, in one heating region, _{the portion other than the image heating unit PR i} is designated as the non-image heating unit PP, and heating is performed at a temperature lower than _{that of the image heating unit PR i.} The details of the heater control method according to the image information and the heater control correction method according to the predicted heat storage amount under the above conditions will be described below.

6. Heater control method according to image information When the video controller 120 receives image information from the host computer, it determines what kind of image is formed in each heating region. Then, the planned heating temperature FT, which is a planned value of the control target temperature TGT, is determined so that the image having a large amount of toner is heated at a higher temperature. Specifically, according to the toner amount conversion value obtained by converting the image density of each color obtained from the CMYK image data into the toner amount, the image having a high toner amount conversion value is heated at a higher temperature. The planned heating temperature FT is determined.

(Method of determining the planned heating temperature)
First, a method of acquiring the toner amount conversion value D will be described. Image data from an external device such as a host computer is received by the video controller 120 of the image forming device and converted into bitmap data. The number of pixels of the image forming apparatus of this embodiment is 600 dpi, and the video controller 120 creates bitmap data (image density data of each CMYK color) corresponding to the number of pixels. The image forming apparatus of this embodiment acquires the image density of each CMYK color for each dot from the bitmap data, and converts this into a toner amount conversion value D.

Figure 6 is planned, in Example 1, to get the maximum value D _{MAX (i)} of the toner amount conversion value D of the image heating unit PR _i in the heating areas (e.g. A _i) in each page, in accordance with this It is a figure which showed the flow which determines a heating temperature. When the conversion to the bitmap data is completed as described above, the flow starts from S601. In S602, it is confirmed whether the image heating unit PR _i exists in the heating region A _{i , and if there is no image heating unit PR i} , the process proceeds to S610, the planned heating temperature PT for the non-image heating unit PP is set, and the process ends. If there is an image heating unit PR _i is the image density detection of each dot in the image heating unit PR _i is started in S603. From the image data converted into CMYK image data, d (C), d (M), d (Y), and d (K), which are the image densities of each of the C, M, Y, and K colors for each dot, can be obtained. In S604, d (CMYK), which is the total value, is calculated. This is performed for all the dots in the image heating unit PR _i , and when the acquisition of d (CMYK) for all the dots is confirmed in S605, these are converted into the toner amount conversion value D in S606.

Here, the image information in the video controller 120 is an 8-bit signal, and the image densities d (C), d (M), d (Y), and d (K) per toner single color are from the minimum density of 00h to the maximum. It is expressed in the range of concentration FFh. Further, d (CMYK), which is the total value of these, is a 2-byte 8-bit signal. As described above, in S606, this d (CMYK) value is converted into the toner amount conversion value D (%). Specifically, the minimum image density 00h per toner single color is set to 0%, and the maximum image density FFh is set to 100%. This toner amount conversion value D (%) corresponds to the toner amount per unit area on the actual recording material P, and in this embodiment, the toner amount on the recording material is 0.50 mg / cm ² = 100%. There is.

_{Then, in S607, the maximum toner amount conversion maximum value D MAX} (i) (%), which is the maximum value, is extracted from the toner amount conversion value D (%) of all the dots in the image heating unit PR _i. d (CMYK) is the total value of a plurality of toner colors, and the value of the maximum toner amount conversion value D _MAX (i) may exceed 100%. In the image forming apparatus of this embodiment, the amount of toner on the recording material P ^{is adjusted so that the upper limit is 1.15 mg / cm 2} (corresponding to 230% in terms of the toner amount conversion value D) for all solid images. When the maximum toner amount conversion value D _MAX (i) is obtained in _{S607, the FT i} value (details will be described later), which is the heating temperature corresponding to the _{maximum toner amount conversion value D MAX (i), is the image heating unit PR.} It is set as the planned heating temperature for _i. Next, verify the non-image heating unit PP is present in the heating region A _i at S609, if there is no non-image heating unit PP, as flow ends. If the non-image heating unit PP is present, the process proceeds to S610, the planned heating temperature PT for the non-image heating unit PP is set, and the process ends.

The above flow is performed for heating area _A 1 to A _7, for each region, scheduled heating temperature FT _i respectively corresponding to the toner amount for the image heating unit PR _i converted maximum value _{D MAX} (i) is set Then, the planned heating temperature PT is set for the non-image heating unit PP.

FIG. 7 shows the relationship between the maximum toner amount conversion value D _MAX (i) and the planned heating temperature FT _i in this embodiment (i = 1 to 7). In this embodiment, the planned heating temperature FT _i is variable in 5 steps according to the maximum toner amount conversion value D _{MAX (i).} For an image having a large toner amount conversion maximum value _DMAX (i) and a large amount of toner, a high temperature is set as the _{planned heating temperature FT i so that the toner is sufficiently melted.} A planned heating temperature PT (for example, 120 ° C.) lower than _{that of the image heating unit PR i} is set for the non-image heating unit PP on which an image is not formed. The planned heating temperature PT is a fixed value.

7. Heater control correction method according to the predicted heat storage amount As described above, for each of the heating regions A _{1 to} A ₇ , the image heating unit PR _i is set to the maximum value D _MAX (i) in terms of the amount of toner. The corresponding planned heating temperature FT _i is set, and the planned heating temperature PT is set for the non-image heating unit PP. The configuration of the first embodiment is a control in which the planned heating temperature thus determined is corrected according to the predicted heat storage amount of each heating region, and is one of the heating conditions when actually heating the recording material P. The target temperature TGT (details will be described later) is determined.

(Method of determining the predicted heat storage amount)
First, in this embodiment, heat storage counters indicating the heat history for each of _{the heating regions A 1 to} A _{7 are provided.} Assuming that the value of the heat storage counter is CT, the heat storage counter value CT indicates how much each heating region is heated, how much heat is dissipated, the heating history, and the heat dissipation history (details will be described later). .. Then, the region heat storage amount HRV as the predicted heat storage amount for the _{heating regions A 1 to} A ₇ is determined by using the value CT of the heat storage counter.

In determining the area heat storage amount HRV _i for a single heating region _{A i,} the heating area _{A i} and heating area _{A i-1,} the value of the heat accumulation counter for _{A i + 1 CT} i adjacent thereto, _{CT i-1} , CT _{i + 1} is used (details will be described later). In the first embodiment, the region heat storage amount HRV as the predicted heat storage amount is obtained for each page (immediately after the printing of the page is executed), and on the next page, the recording material P is actually obtained according to this value. _{The control target temperature TGT (PR i} ), which is the temperature at which the heating unit PR _{i is heated, is determined.} The heat storage counter value CT and the region heat storage amount HRV will be described in detail below.

7-1. Counting method of heat storage counter A method of determining the heat storage counter value CT showing the heating history and heat dissipation history of each heating region will be described. The heat storage counter for each heating region counts the heat history according to a specified method according to the heating operation for the heating region and the paper passing condition of the recording material. The count value CT of the heat storage counter is represented by the following (Equation 1).
CT = (TC x LC) + (WUC + INC + PC)-(RMC + DC) ... (Equation 1)

With reference to FIG. 8, (TC × LC), (WUC + INC + PC) as the heating history, and (RMC + DC) as the heat dissipation history in (Equation 1) will be described. The heat storage count value CT in this embodiment shall be updated every page (immediately after printing of that page is executed).
As shown in FIG. 8A, TC is a value determined according to the control target temperature TGT (PR _{i ) when heating the image heating unit PR i} of the recording material, and is a control target temperature TGT ( The _{higher the temperature of PR i} ), the larger the value.
As shown in FIG. 8B, LC is a value determined according to the heating distance HL (mm) when _{the image heating unit PR i is heated, and the value increases as the HL becomes longer.} It has become.
In the heating region where the image is formed, _{(TC × LC) for the image heating unit PR i} and the other non-image heating unit PP is added to obtain one page.

The other WUC, INC, and PC are fixed values that are counted with respect to the start-up at the start of printing, the space between papers, and the post-rotation at the end of printing, as shown in FIG. 8 (c). These WUCs, INCs, and PCs can be changed according to, for example, the start-up time, the space between papers, and the back rotation time depending on the operating conditions. The parameter representing the heating history is not limited to the above, and other parameters indicating the temperature history of the heater and the history of the power supplied to the heating element may be used.

Further, RMC and DC are fixed values that are counted against the heat taken from the image heating device and the heat radiation to the outside air by passing the recording material P through the paper, as shown in FIG. 8C. , FIG. 8C shows the value when one sheet of LETTER size paper is passed. These RMCs and DCs can be changed to values corresponding to them depending on the type of recording material and environmental conditions. The heat dissipation count DC is counted at times other than printing, and when the specified time elapses, the specified value is counted (for example, three counts up in one minute). Further, the parameter representing the heat dissipation history is not limited to the above, and other parameters indicating the passage history of the recording material in the heating region and the period during which the power is not supplied to the heating element may be used. ..

As described above, the count value CT of the heat storage counter in this embodiment is counted for each page (immediately after the printing of that page is executed) from only the heat history information for each area in each area. be.

7-2. Method for determining the area heat storage amount In Example 1, the area heat storage amount HRV as the predicted heat storage amount is obtained for each page (immediately after the printing of the page is executed) from the above heat storage count value CT. Then, on the next page, the control target temperature TGT (PR _i ), _{which is the temperature at which the image heating unit PR i} of the recording material P is actually heated, is determined according to this value. First, when representing the count value of the heat accumulation counter for heating area _{A i} in CT _i, area heat storage amount HRV _i to the heating area _{A i} is the heat storage count value _{CT i-1, CT} i, from _{CT i + 1} of the following (Formula 2 ) Is calculated.
HRV _i = CT _i + α (CT _i-1 + CT _{i + 1} ) ... (Equation 2)
Here, α is a constant.

As can be seen from equation (2), area heat storage amount HRV _i for a single heating region _{A i} has a heating area _{A i} is the heating region, adjacent the heating area _A i-1 of both _{adjacent, A i + 1} of the heat is a value determined from the history, the value is a value indicating the predictive heat storage amount of the heating area a _i. The area heat storage amount HRV _{i of A 1} and A ₇ which are the heating areas at both ends is determined from the heat history of the heating area and one heating area adjacent to the heating area.

The constant α in (Equation 2) is a value indicating the degree of influence of the heat history of the adjacent heating region on the predicted heat storage amount of the heating region, and α = 0.2 in the configuration of Example 1. As described above, in the image forming apparatus according to the present embodiment, the predicted heat storage amount of each heating region is determined in consideration of the heat history of the heating region adjacent to the region, thereby determining the prediction accuracy of the predicted heat storage amount. It is improving. In this embodiment, a more appropriate control target temperature TGT (PR _i ) can be obtained by correcting the planned heating temperature FT _i for the image heating unit PR _i using the region heat storage amount HRV _{i determined in this way.} Be done.

FIG. 9 shows the relationship between the regional heat storage amount HRV _i and the correction value VA with respect to the planned heating temperature FT _i. The relationship between the heat storage amount HRV _{i in} this region and the correction value VA with respect to the planned heating temperature FT _i is determined from the results of confirming the heat storage state and the image characteristics after fixing in advance with the fixing device of Example 1. In the present embodiment, with respect to the non-image heating unit PP, not perform the correction by the area heat storage amount HRV _i (area heat storage HRV _i control target temperature TGT (PP) = 120 ℃ regardless of the value of) the And.

7-3. Method for Determining Control Target Temperature FIG. 10 shows a flow for determining the control target temperature TGT for the image heating unit PR _{i and the non-image heating unit PP in the heating region A i in this embodiment.} Here, the current page number is represented by PN. When the flow starts, first, in S1001, the area heat storage amount HRV _i [PN-1] up to the previous page is acquired. In S1002, it is confirmed whether or not the image heating unit PR _i exists in the heating region A _i. If the image heating unit PR _i is present, S1003 acquires the _{planned heating temperature FT i} determined by the control flow of FIG. 6 described above for the _{image heating unit PR i.} If the image heating unit PR _i does not exist, the process proceeds to S1006 to determine the control target temperature for the non-image heating unit PP.

In S1004, the planned heating temperature FT _{i for the image heating unit PR i obtained in S1003}
Is corrected according to the predicted heat storage amount. First, according to FIG. 9 described above, the correction value VA (HRV _i [PN-1]) _{for the planned heating temperature FT i is selected according to the region heat storage amount HRV i} [PN-1] obtained in S1001 up to the previous page. Will be done. Next, this correction value VA (HRV _i [PN-1]) is used to _{correct the planned heating temperature FT i} using the following (Equation 3), and the control target temperature TGT (for the _{image heating unit PR i) (} PR _i ) is determined.
TGT (PR _i ) = FT _i + VA (HRV _i [PN-1]) ... (Equation 3)

As described above, the control target temperature TGT for the image heating unit PR _i (PR _i) is determined in S1004, the non-image heating unit PP to heating area _{A i} in S1005 confirms whether there exists. When the non-image heating unit PP is present, in S1006 and S1007, the planned heating temperature PT and the control target temperature TGT (PP) for the non-image heating unit PP are determined (TGT (PP) = PT), and the process proceeds to S1008. If the non-image heating unit PP does not exist, the process proceeds directly from S1005 to S1008. In S1008, printing of the current page (page number = PN) is executed using the control target temperature TGT determined in the flow up to this point. Next, in S1009, the area heat storage amount HRV _i [PN] up to the current page is calculated, and in S1010, the page number is updated to that of the next page. It is confirmed in S1011 whether the printing is completed, and if the printing is completed on the current page, the flow ends here, and if the printing is continued, the flow from S1001 is repeated.

8. Comparison with Comparative Example From here, it will be described how the present invention improves the prediction accuracy of the predicted heat storage amount while comparing it with the configuration of the comparative example. A case where printing is performed using the two types of image patterns shown in FIGS. 11 and 13 shown below will be described as an example.

8-1. Description of Image Patterns The image patterns of FIGS. 11 and 13 will be described. FIG. 11 shows images P1 and P2 formed on LETTER size paper. These images P1 and P2 are tertiary colors having uniform image densities of cyan (C), magenta (M), and yellow (Y), and the image densities of P1 and P2 are converted to the toner amount conversion value D (%). It is assumed that both converted values are 210%. It is assumed that no image is formed in the heating regions, A ₁ , A ₂ , A ₄ , A ₆ and A _7. The image heating portions PR _i in the heating regions A ₃ and A ₅ are designated as PR ₃ and PR ₅ , the start portion thereof is indicated by PRS, and the end portion is indicated by PRE. In this embodiment, the start portion PRS of the image heating portion PR _i is set to the tip side of the recording material by 5 mm from the tip of the image. Further, the end portion PRE of the image heating portion PR _i in this embodiment is set to the rear end side of the recording material by 5 mm from the rear end portion of the image.

Here, as described above, the temperature at which the recording material P is actually heated is referred to as the control target temperature TGT. In this embodiment, the control target temperature TGT (PP) for the non-image heating unit PP (for example, the planned heating temperature PT = 120 ° C.) is changed to the heating of the image heating unit PR _{i by the start portion PRS of the image heating unit PR i} . The heater temperature is raised to the control target temperature TGT (PR _{i) to be used.} That is, the temperature rise is started so that the surface temperature of the fixing film 202 reaches the temperature required for fixing the image by the start portion PRS of the _{image heating portion PR i.}

In Example 1, the heating distance HL (mm) shown in FIG. 8B _{is the sum of the length of the image heating unit PR i in} the recording material transport direction and the distance required for the above-mentioned temperature rise. It was a distance. The LC value in the above-mentioned (Equation 1) is determined according to the heating distance HL (mm), and is used for calculating the heat storage count value CT. In the image pattern of FIG. 11, _{the distance HL (mm) obtained by heating the image heating units PR 3} and PR ₅ is 279 mm, which is equal to the length in the transport direction of the LETTER size paper, and the above-mentioned temperature raising operation is the recording material. It shall start from the tip. Further, the heating distance HL (mm) for the image used in the following description is also the distance obtained by adding the length of the image heating unit PR in the recording material transport direction and the distance required for the temperature raising operation in the same manner as described above.

12, FIG. 6, was determined in accordance with the method described in FIG. 7, in the heating areas _A 1 to A ₇ of the image pattern of Figure 11, the image heating portion PR _i toner amount conversion maximum value _{D MAX} scheduled heating temperature It is a value of the planned heating temperature PT of FT and the non-image heating part PP.

Figure 13 is an image P3 in the heating area _{A 3,} the image P4 to the heating area _{A 4} is an image pattern image P5 is formed in the heating region _{A 5.} In the images P3, P4, and P5, the tertiary colors of cyan (C), magenta (M), and yellow (Y) having a toner amount conversion value D (%) of 40% are uniformly formed (toner amount conversion maximum value D _MAX). (I) (%) = 40%). It is assumed that no image is formed in the heating regions, A ₁ , A ₂ , A ₆ and A _7. The image heating portions PR _i in the heating regions A ₃ , A ₄ , and A ₅ are designated as PR ₃ , PR ₄ , and PR ₅ , the start portion thereof is indicated by PRS, and the end portion is indicated by PRE.

8-2. Explanation of Comparison Conditions The following printing is performed using the two types of image patterns of FIGS. 11 and 13 described above. First, 30 consecutive image patterns of FIG. 11 are printed on LETTER size paper. Immediately after that, one image pattern of FIG. 13 is printed on LETTER size paper. At this time, when printing the image pattern of FIG. 13, what kind of temperature is set for the control target temperature TGT for each heating region at the transport direction position LH in the drawing will be described below. Comparison is made between Example 1 and Comparative Example.

8-3. The present embodiment of Example 1, the above-described (Equation 1), using the area heat storage amount HRV _i obtained from equation (2), according to FIG. 9, to correct the scheduled heating temperature FT _i for the image heating unit PR _i , Control target temperature TGT (PR _i ) is determined. As described above, FIG. 9 shows the relationship between the _{region heat storage amount HRV i} and the correction value VA with respect to the planned heating temperature FT _i.

First, when the LETTER size paper were continuously printed with the image pattern of Figure 11, to check the space heat storage amount HRV _i of Example 1 in the heating areas _A 1 to A _7.
FIG. 15A shows the transition _{of the regional heat storage amount HRV i} in Example 1 when the image pattern of FIG. 11 is continuously printed. LM1 to LM5 in FIG. 15A show the region heat storage amount HRV in which the correction value VA changes in the relationship between _{the region heat storage amount HRV i} and the correction value VA with respect to the control target temperature TGT (PR _{i) shown in FIG.} Shows the value. Specifically, the values of LM1, LM2, LM3, LM4, and LM5 are 20, 50, 100, 150, and 200, respectively.

As shown in FIG. 15A, _{the transition of the regional heat storage amount HRV i} in Example 1 is divided into four types. First, the increase rate of most areas the quantity of thermal storage HRV _i fast, a heating area A _3, A ₅ on which an image is formed, the next increase speed is high, flanked by heating region on which the image is formed It was a heating area _{a 4.} Then the faster the rate of increase of area heat storage HRV _i is the heating area A _2, A ₆ in contact with the heating region only one side image is formed, the heating region increased most rate located slow both ends A ₁ and A ₇ . The values of the area heat storage amount immediately after printing 30 sheets are 223.8 for _{HRV 3} and HRV ₅ , 152.1 for _{HRV 4} , 128.2 for _{HRV 2} and HRV ₆ , and 89.4 for _{HRV 1} and HRV _7. ..

About the control target temperature TGT set at the transport direction position LH in the drawing when printing the image pattern of FIG. 13 immediately after printing 30 sheets of LETTER size paper with the image pattern of FIG. 11 using FIG. explain. In FIG. 16, the maximum toner amount conversion value D _MAX (i) _{for the image heating unit PR i} in each heating region in the image pattern of FIG. 13 is shown.
The corresponding planned heating temperature FT _i and the planned heating temperature PT for the non-image heating portion PP are shown. Based on these values, the control target temperature determined in each configuration of Example 1, Comparative Example 1-1 and Comparative Example 1-2 described later is shown.

_{As described above, in the first embodiment, the region heat storage amount HRV i} is calculated as the predicted heat storage amount of each heating region by printing 30 image patterns of FIG. 11 immediately before, and the control target temperature is calculated from the above (Equation 3). TGT (PR _i ) is decided. In Example 1, _{the values of TGT (PR 3} ), TGT (PR ₄ ), and TGT (PR ₅ ) are 185, 187, and 185 ° C.

8-4. Explanation of Comparative Example 1-1 In Comparative Example 1-1, the planned heating temperature FT _i is not corrected by the amount of heat storage in each heating region, and the control target temperature TGT (PR) in _{the image heating unit PR i} of each heating region is used as it is. _i ). Since the correction by the amount of heat storage is not performed in Comparative Example 1-1, the planned heating temperature FT _i is used as it is as the _{control target temperature TGT (PR i).} Therefore, as shown in FIG. 16, in Comparative Example 1-1, _{the values of TGT (PR 3} ), TGT (PR ₄ ), and TGT (PR ₅ ) are 193, 193, and 193 ° C.

8-5. Explanation of Comparative Example 1-2 In Comparative Example 1-2, the predicted heat storage amount of each heating region is determined only from the heat history of the heating region, and from this predicted heat storage amount, the planned heating temperature FT for the _{image heating unit PR i The configuration is such that i} is corrected and the control target temperature TGT (PR _i ) is determined. That is, it is a comparative configuration in which the count value CT _i of the heat storage counter is used as it is as the predicted heat storage amount.

_{FIG. 14 shows the relationship between the count value CT i} of the heat storage counter in Comparative Example 1-2 and the correction value VA with respect to the planned heating temperature FT _i. FIG. 15B shows the transition _{of the heat storage count value CT i} in Comparative Example 1-2 when the image pattern of FIG. 11 is continuously printed. The heating area _A 3, _{A 5} on which an image is formed, heating region _A 1 where no image is _{formed, A 2, A 4, A} 6, different changes in the _{A 7} in the heat storage count value CT _i, an image is formed The heat storage count value CT _i increases faster in the heating region. The heat storage count values immediately after printing 30 sheets _{are 195.8 for CT 3} and CT ₅ , and 74.5 for CT ₁ , CT ₂ , CT ₄ , CT ₆ , and CT ₇ .

_{In Comparative Example 1-2, the heat storage count value CT i} is calculated as the predicted heat storage amount of each heating region by the immediately preceding 30-sheet print, and the following (Equation 4) is used by using the correction value VA obtained from FIG. The control target temperature TGT (PR _i ) is further determined.
TGT (PR _i ) = FT _i + VA (CT _i [PN-1]) ... (Equation 4)

As shown in FIG. 16, in Comparative Example 1-2, _{the values of TGT (PR 3} ), TGT (PR ₄ ), and TGT (PR ₅ ) are 187, 191 and 187 ° C.

8-6. Comparison of Examples and Comparative Examples As described above, although the print history and the print conditions are the same, the _{control target temperature for the image heating unit PR i} differs depending on the configuration. In Example 1, since the heat storage amount is predicted in consideration of the influence of the heat history of the adjacent heating region, a value closer to the actual heat storage amount can be predicted with higher accuracy than in the comparative example. _{Therefore, the values of the control target temperatures TGT (PR 3} ), TGT (PR ₄ ), and TGT (PR ₅ ) with respect to the image heating region in FIG. 13 are set to be lower than those in the comparative example.

In Comparative Example 1-1 and Comparative Example 1-2 in which the control target temperature is set to a higher temperature than in Example 1, the amount of heat originally required is larger than the amount of heat originally required, and excessive heat is supplied to the image heating region. Become. As a result, in Comparative Example 1-1 in which the amount of heat storage is not considered at all, the images P3, P4, P are due to overheating.
The toner of No. 5 adhered to the surface of the fixing film 202, and after one rotation, it adhered to the recording material, so-called hot offset occurred. Further, in Comparative Example 1-2 in which the control target temperature is determined by considering only the heat history of the heating region, the control target temperatures TGT (PR ₃ ) and TGT (PR _{4) do not occur as described above.} ), TGT (PR ₅ ) is set to a higher temperature than in Example 1. Therefore, the originally unnecessary power is consumed by the amount of the high temperature setting, and the power saving property is lowered.

As described above, in the image forming apparatus for adjusting the heating conditions of a plurality of heat generating blocks provided in the longitudinal direction according to the image information, in the first embodiment, the amount of heat stored in each heating region can be predicted with high accuracy. This makes it possible to obtain a good output image while improving power saving.

In the above embodiment, the control target temperature is set as the heating condition according to the predicted heat storage amount, but as the heating condition, for example, the supply power supplied to the heater may be adjusted according to the predicted heat storage amount in each heating region. .. Further, for example, as a heating condition, the heating start timing may be made variable according to the predicted heat storage amount, and when the predicted heat storage amount is small, the heating start timing may be advanced to further warm the fixing device. Further, in the description of this embodiment, the control target temperature at the time of the previous printing was used as the heat history to be referred to when predicting the amount of heat storage, but the power supplied to the heater is referred to and the amount of power is adjusted. It is also possible to predict the amount of heat storage. Further, in this embodiment, the region heat storage amount HRV as the predicted heat storage amount is acquired (updated) page by page, that is, every time one recording material passes through the image heating unit, but the frequency of update is a predetermined page. It may be every time (every time the specified number of sheets is passed).

In order to simplify the description, in the first embodiment, with respect to the non-image heating unit PP, area heat storage HRV _i correction by is not performed (a region heat storage amount HRV _i values in relation without control target temperature TGT the (PP ) = 120 ° C.) The description was given using the configuration. However, the non-image heating portion PP can also be corrected by the _{regional heat storage amount HRV i to further reduce power consumption.}

[Example 2]
In Example 2 of the present invention, it is set a plurality of image heating section PR in the heating area A _i, optimal control target temperature TGT is configured to be set for each image heating portion PR. By doing so, it is possible to further improve the power saving property as compared with the configuration used in the first embodiment. Since the configurations of the image forming device, the fixing device (image heating device), the heater, and the heater control circuit in the second embodiment are the same as those in the first embodiment, the description thereof will be omitted. Matters not particularly described here in the second embodiment are the same as those in the first embodiment.

9. Method for determining control target temperature for a plurality of image heating units PR This will be described using the image pattern shown in FIG. FIG. 17 shows images P6 to P11 formed on LETTER size paper. These images P6 to P11 are tertiary colors having a uniform image density of cyan (C), magenta (M), and yellow (Y). The value obtained by converting the image densities of P6 to P8 into the toner amount converted value D (%) is 210%, and the value obtained by converting the image densities of P9 to P11 into the toner amount converted value D (%) is 40%. The image heating units set for the respective images P6 to P11 are PR _3-1 and PR _4-1 and PR _5-1 and PR _3-2 , PR _4-2 and PR _5-2. .. The length of all the image heating units in the transport direction is 65 mm, and the image heating units PR _3-2 , PR _4-2 , and PR _5-2 start portions PRS 3-2, 4-2, and 5-2 are recording materials. It is located 175 mm downstream from the tip PLE. In this embodiment, for example, in the heating area _{A 4,} separate control target temperature with respect to _{PR 4-1} and _{PR 4-2} is set. At this time, just before each image heating unit, with reference to the predicted heat storage amount of the heating area A _4, this prediction heat storage amount, the same correction as in Example 1 are carried out.

9-1. Method for updating the regional heat storage count value and the regional heat storage amount In Example 2, the regional heat storage amount HRV _{i values are updated at specified intervals, and the regional heat storage amount HRV i is updated according to the region heat storage amount HRV i} until immediately before the start of each image heating unit PR. The control target temperature TGT (PR) for the image heating unit PR is determined. That is, in this embodiment, the value of the region heat storage amount HRV _i as the predicted heat storage amount is updated a plurality of times while one recording material passes through the fixing portion.

Here, in this embodiment, the update interval of the region heat storage amount HRV _i is 5.58 mm in terms of the transport distance of the recording material, and this length will be referred to as the update interval LF thereafter. The shorter the update interval LF is set, the more the value of the _{region heat storage amount HRV i closer to the actual heat storage amount can be obtained.} However, if the distance is set shorter than necessary, the area heat storage amount HRV and the heat storage count value CT, which will be described later, must be calculated frequently. The load (shown in the figure) increases more than necessary, which is not preferable. Therefore, in the second embodiment, the update interval LF capable of obtaining the region heat storage amount HRV with necessary and sufficient accuracy while avoiding the above-mentioned adverse effects is a distance equivalent to 1/50 of the length in the transport direction of the LETTER size paper. 5.58 mm was adopted. An optimum value can be used for the update interval LF according to the configuration of the apparatus, the printing speed, and the like.

In this embodiment, the region heat storage amount HRV _i is sequentially updated at the update interval LF, and the control target temperature for the image heating unit PR is determined according _{to the region heat storage amount HRV i} until immediately before the start of each image heating unit PR. Determine TGT (PR). Let n be the number of updates since the power of the image forming apparatus is turned on and _{the update of the area heat storage amount HRV i is started.} The update count n is reset when the power is turned on, and then counted up at the update interval LF.

9-2. In decision process Example 2 regions heat storage amount, in the heating region _{A i, HRV i [n]} the area heat storage capacity, the heat storage count _value, and _{CT i [n].} The initial value of the area heat storage amount when the power is turned on is HRV _{i [0]} , and the initial value of the heat storage count is CT _{i [0]} . As in Example 1, area heat storage amount in the heating area _{A i HRV i [n]} is the heating region _{A i, A i-1,} A i + 1 in the heat storage count value _{CT i [n], CT i} -1 [n _] , CT _{i + 1 [n]} is used, and it is determined by the following (Equation 5).
HRV _{i [n]} = CT _{i [n]} + α (CT _{i-1 [n]} + CT _{i + 1 [n]} ) ... (Equation 5)
Note that α is a constant, and in Example 2 as in Example 1, α = 0.2.

9-3. Counting Method of Heat Storage Counter Next, the heat storage count value CT _{i [n]} in this embodiment will be described in detail. The parameters used when calculating the heat storage count value CT _{i [n]} of this example are basically the same as those of (Equation 1) in Example 1. However, as the values of these parameters, the values updated at the above-mentioned update interval LF are used. The heat storage count value CT _{i [n]} in Example 2 is represented by the following (Equation 6).
CT _{i [n]} = CT _{i [n-1]} + (TC × LC) _{i [n]} + (WUC + INC + PC) _{i [n]} − (RMC + DC) _{i [n]} … (Equation 6)
However, CT _{i [0]} = CT _INT

With reference to FIG. 18, TC, LC, RMC, DC, and WUC, INC, PC in (Equation 6) will be described. As shown in FIG. 18A, the TC of (Equation 6) is a value determined according to the control target temperature TGT when heating the recording material P, and the higher the control target temperature TGT, the higher the temperature. The value is increasing. Note that FIG. 18A has exactly the same contents as FIG. 8A in Example 1. As shown in FIG. 18B, the LC of (Equation 6) is a value determined according to the distance HL (mm) that was heated when the recording material P was heated, and the longer the HL, the more. The value is increasing. _{In the second embodiment, the (TC × LC) i [n]} term of (Equation 6) is obtained according to the control target temperature TGT used in the update interval LF and the heating distance HL (mm). Therefore, the HL in FIG. 18B is set with respect to the range of values corresponding to the update interval LF (5.58 mm). In the (TC × LC) _{i [n]} term, when the control target temperature TGT changes within the update interval LF, the TC × LC corresponding to each control target temperature TGT and the heating distance is updated at the update interval. A value can be obtained by adding LF.

As shown in (c) of FIG. 18, WUC, INC, and PC are values that are counted with respect to the start-up at the start of printing, the space between papers, and the post-rotation at the end of printing, and (c) in FIG. The value shown in is the value for the update interval LF. In the second embodiment, the time required for the start-up at the start of printing, the space between papers, and the post-rotation at the end of printing in the normal operation is 180 times, 10 times, and 180 times of the update interval LF, respectively. The (WUC + INC + PC) _{i [n]} term of (Equation 6) corresponds to each operation at each update interval LF at the time of start-up at the start of printing, between papers, and at the time of post-rotation at the end of printing. A value is obtained using the value of c).

Further, the RMC and DC of (Equation 6) are fixed values that are counted against the heat taken from the image heating device and the heat radiation to the outside air by passing the recording material P through the paper, and are the fixed values (d) in FIG. ) Is the value for the update interval LF. Similar to Example 1, these RMCs and DCs can be changed to values corresponding to them depending on the type of recording material and the environmental conditions. The (RMC + DC) _{i [PN, n]} term of (Equation 6) is obtained by using the value of (d) of FIG. 18 for each update interval LF. Further, the heat dissipation count DC of the second embodiment is counted other than at the time of printing as in the first embodiment, and when the specified time elapses, the specified value is counted (for example, the count is increased by 3 in one minute).

The initial value of the area heat storage amount when the power is turned on is HRV _{i [0]} , and the initial value of the heat storage count is CT _{i [0]} . Here, the heat storage count value CT _{i [0]} at n = 0 is the initial stage when the power is turned on or when returning from the power saving standby mode (hereinafter referred to as sleep mode) used in a general image forming apparatus. The value. The value of the heat storage count value CT _{i [0]} can be obtained by using the value obtained based on _{the final value CT i [n]} of the heat storage count stored at the time of the previous power off or the transition to the sleep mode. good. Further, it is also possible to use a value corresponding to the detection temperature of a temperature detecting means such as a thermistor provided in the image heating device when the power is turned on or when returning from the sleep mode. The heat storage count value obtained in this way when the power is turned on or when returning from the sleep mode is defined as the heat storage count initial value CT _INT . _{The heat storage count value CT i [0]} when the heat storage count is started is set to the above-mentioned initial heat storage count value CT _INT.

9-4. Heat storage count value, the update flow diagram 19 of a region the heat storage amount, in Example 2, the power-on or print starts immediately after returning from the sleep mode, the heat storage count value of the heating area A _i up moves again to the sleep mode, The calculation flow of CT _{i [n]} and region heat storage amount HRV _{i [n] is shown.} First, in S1901, the above-mentioned initial value CT _INT of the heat storage count is acquired. In S1902, n = 0, and in S1903, the initial value CT _INT value is set in _{CT i [0].} Printing starts at S1904.

In S1905, when the transport distance between the fixing film 202 and the pressure roller 208 advances by the update interval LF, the value of n is incremented in S1906, and then the renewal value CT _{i [n]} of the heat storage count is calculated in S1907. .. In this embodiment, the heat storage count values CT _{i-1 [n]} and CT _{i + 1} of the adjacent heating regions A _i-1 and the heating regions A _{i + 1 in the same flow as described above.
[N]} has been calculated. _{In S1908, the region heat storage amount HRV i [n]} represented by the above-mentioned (Equation 5) is calculated using the above values. After that, it is confirmed in S1909 whether or not printing is continued, and if printing is continued, the flow from S1905 is repeated. When the end of printing is confirmed in S1909, the end of printing is completed in S1910.

After the printing is completed, as described above, in S1911, the value of n is incremented when the specified time elapses, and the heat dissipation count DC counts up by the specified value (for example, counts up by 3 in 1 minute). Then, in conjunction with this, the heat storage count value CT _{i [n]} and the region heat storage amount HRV _{i [n]} are updated. It is confirmed in S1912 whether or not there is a next print instruction, and if the next print instruction comes, the flow from S1904 is repeated.

If the next print does not come, check whether to shift to the sleep mode in S1913. In the second embodiment, if the next print command does not come within a predetermined elapsed time (for example, 5 minutes) after the printing is completed, the sleep mode is entered. In S1913, it is confirmed whether or not the elapsed time specified above has been reached since the end of the previous print, and if the elapsed time has reached the specified time, sleep is entered in S1914 and the flow ends. If the specified elapsed time has not been reached, the process returns from S1913 to S1911 and the flow is continued. When a print command is received during sleep, the sleep mode is resumed and the flow is started from the beginning of FIG.

As described above, the heat storage count value CT _{i [n]} and the area heat storage amount HRV _{i [n]} are obtained every update interval LF at the time of printing and at every specified time except at the time of printing.

9-5. Method for determining control target temperature In this embodiment, for each image heating unit PR, the planned heating temperature is determined by the same method as in Example 1 before the page on which the image heating unit PR exists reaches the fixing device 200. The FT is determined in advance. Then, the planned heating temperature FT for each image heating unit PR is corrected by using the region heat storage amount HRV immediately before the start unit PRS of each image heating unit PR, and is set as the control target temperature TGT for the image heating unit PR. Further, in the heating region A _i , the image heating unit PR at a position where the start unit PRS corresponds to the interval from the number of updates n to n + 1 is displayed _{as PR i [n].}

In the second embodiment, the control target temperature TGT (PR _{i [n] ) for the image heating unit PR i [n]} is determined as follows. That is, in consideration of the temperature rise time at which the surface temperature of the fixing film 202 reaches the temperature required for fixing the image from the start of heating, the region heat storage before the transfer distance corresponding to 10 times the update interval LF. The amount HRV _{i [n-10]} is used. In this embodiment, as described above, the area heat storage amount HRV _{i [n-10]} before the transfer distance corresponding to 10 times the update interval LF was used, but the heat capacity of the image heating device to be used and the supply to the heater. Depending on the electric power, it is sufficient to select how much the area heat storage amount before the image heating unit is used.

In the image forming apparatus of this embodiment, there is where the image heating portion PR of the heating area A _i, the position of the beginning PRS is either present in any number of updates interval described above is known in advance. Therefore, when determining a control target temperature TGT (PR) for heating area A _i each image heating portion PR with the, are determined in advance may use area heat storage amount HRV in which the number of updates. Therefore, once the region heat storage amount HRV used for correcting the control target temperature TGT (PR) for the image heating unit PR is obtained, this value is used to determine the control target temperature TGT (PR), and the image heating unit PR _i The temperature raising operation for heating with respect to _{[n] is started.}

As described above, in this embodiment, when the control target temperature TGT (PR _{i [n] ) for the image heating unit PR i [n]} is determined, the region heat storage amount HRV _{i [n-10]} is used. Here, in the same manner as in Example 1, the predetermined heating temperature FT is displayed _{as FT i [n] on the image heating unit PR i [n].} The control target temperature TGT (PR _{i [n]} ) for the image heating unit PR _{i [n]} is obtained by correcting the planned heating temperature FT _{i [n]} using the region heat storage amount HRV _{i [n-10].} Will be. At this time, the method of applying the correction is the same as in the first embodiment, according to the relationship between the region heat storage amount HRV and the correction value VA shown in FIG. 9, and is represented by the following (Equation 7).
TGT (PR _{i [n]} ) = FT _{i [n]} + VA (HRV _{i [n-10]} ) ... (Equation 7)

As in Example 1, in this example as well, the non-image heating unit PP is not corrected by the regional heat storage amount HRV (control target temperature TGT (PP) = 120 ° C. regardless of the value of the regional heat storage amount HRV). )

10. Comparison with Example 1 Here, when printing the image pattern of FIG. 17 immediately after printing 29 sheets of LETTER size paper with the image pattern of FIG. 11, the control target set at the transport direction position LH2 in the figure is set. Example 2 and Example 1 are compared with respect to the temperature TGT.
In FIG. 20, in the LH2 portion of FIG. 17, the maximum toner amount conversion value _{DMAX (i) with respect to the image heating portion PR i} in each heating region, the corresponding planned heating temperature FT _i , and the non-image heating portion are shown. The planned heating temperature PT for PP is shown. Further, FIG. 20 shows the control target temperatures TGT (PR _i ) and TGT (PP) in the LH2 portion, and the region heat storage amount HRV _i used when determining them. The control target temperature TGT (PR _i ) for the image heating unit PR _i of Examples 2 and 1 is determined by the correction by the region heat storage amount HRV _i , but there are the following differences.

_{In the first embodiment, the region heat storage amount HRV i [29]} is calculated as the predicted heat storage amount of each heating region by printing the immediately preceding 29 sheets, and using this, the control target temperature TGT (PR _i ) is calculated from the above (Equation 3). Is decided. Therefore, the regional heat storage amount HRV _{i [29]} does not include the heat history of the LH1 part of FIG. 17 on the current page at all. On the other hand, in the second embodiment, in addition to the predicted heat storage amount of each heating region by the immediately preceding 29-sheet print, the heat history up to 10 times before the update number n where the tip PH2 of the LH2 part is located and up to the update number n-10 is included. The area heat storage amount HRV _{i [n-10]} is calculated. Then, using this, the control target temperature TGT (PR _{i [n]} ) is determined by the same method as in Example 1.

In the second embodiment and the first embodiment, there is a difference in the value of the _{regional heat storage amount HRV i by} the amount of heat history up to the number of updates n-10 in the LH1 part of FIG. 17 on the current page. As a result, the control target temperature TGT for the image P10 of the heating area _{A 4 (PR 4-2)} is set to different temperatures. In the second embodiment, the control target temperature TGT (PR _4-2 ) is set to 187 ° C., and in the first embodiment, the temperature is set to 189 ° C. Therefore, in the second embodiment in which the control target temperature is suppressed to a low level, it is possible to further improve the power saving property as compared with the case where the control of the first embodiment is used.

As described above, in the second embodiment, while the recording material P is passing through the fixing nip portion N, _{the value of the region heat storage amount HRV i [n]} is updated at predetermined intervals, and the latest value is used to control the image heating portion. The target temperature was determined. As a result, the predicted heat storage amount of each heating region at that time can be calculated with higher accuracy than in Example 1, so that power saving can be improved by using a more optimum control target temperature.

In this embodiment as well, as in the first embodiment, the heating condition may be electric power or the like instead of the control target temperature.

In order to simplify the description, the second embodiment as well as embodiment 1, with respect to the non-image heating unit PP, not perform the correction by the area heat storage amount HRV _i (control regardless of the value of area heat storage amount HRV _i The explanation was given using the target temperature TGT (PP) = 120 ° C. configuration. However, the non-image heating portion PP can also be corrected by the _{regional heat storage amount HRV i to further reduce power consumption.}
Further, although the heating conditions are set using the image information and the heat history in both Examples 1 and 2, the heating conditions may be set using only the heat history. That is, the heating conditions for controlling each of the plurality of heating elements are the heat history of the heating region heated by one heating element, the heat history of the heating region heated by the heating element adjacent to one heating element, and the heat history of the heating region. It may be set according to.

300 ... Heater, 305 ... Substrate, 301 (301a, 301b) ... Conductor, 303 (303-1 to 303-7) ... Conductor, 302 (302a-1 to 302a-7, 302b-1 to 302b-7) ... heating resistor, 400 ... control circuit, 200 ... image heating device, 202 ... fixing film

Claims (15)

The first rotating body and
A second rotating body that comes into contact with the outer peripheral surface of the first rotating body and that forms a nip portion between the first rotating body and the second rotating body.
A heater in which a plurality of heat generating blocks are arranged in a direction orthogonal to both the transport direction of the recording material and the thickness direction of the recording material.
A control unit that sets the heating conditions for each of the plurality of heat generation blocks for each heat generation block, and the heating conditions for the heat generation block when heating the image unit on the first recording material and the heating conditions on the first recording material. It has a control unit that sets the heating conditions of the heat generating block to be different when heating the non-image part of the above.
The heater is arranged in the internal space of the first rotating body.
An image heating device that heats an image formed on a recording material by passing the recording material through the nip portion.
Among the regions of the nip portion, the region of the nip portion corresponding to the region of the first rotating body heated by the first heat generation block among the plurality of heat generation blocks is the first heating region and the region of the nip portion. Among the plurality of heat generation blocks, the region of the nip portion corresponding to the region of the first rotating body heated by the second heat generation block adjacent to the first heat generation block is defined as the second heating region.
Wherein, the first of the image portion on the recording material, according to the distance in the previous end or et after Tanma the first image portion to be heated by said first heating zone, the first calculating a first quantity of thermal storage in the heating region, the distance in the first of the image portion on the recording material, a second image of the previous edge if et after Tanma heated by the second heating region The second heat storage amount in the second heating region is calculated according to the above.
When the second recording material is conveyed to the nip portion after the first recording material, the heating conditions of the first heat generation block are set according to the first heat storage amount and the second heat storage amount. An image heating device characterized by being set. When there are a plurality of images heated by the first heating region among the image portions on the first recording material, the first image portion is the last after the first image reaches the first heating region. Is the region heated by the first heating region before the image of is passed through the first heating region.
When there are a plurality of images heated by the second heating region among the image portions on the first recording material, the second image portion is the last after the first image reaches the second heating region. The image heating device according to claim 1, wherein the image is a region heated by the second heating region before passing through the second heating region. The image heating device according to claim 1 or 2 , wherein the control unit sets heating conditions of the first heat generation block according to the density of an image of the first image unit. The image heating device according to claim 1 or 2, wherein the heating condition is a control target temperature set for each heat generation block by the control unit. The image heating device according to claim 1 or 2, wherein the heating condition is an amount of electric power supplied to the heat generation block by the control unit. The image heating device according to claim 1 or 2, wherein the heating condition is a timing at which heating of the heat generating block is started by the control unit. The first heat storage amount is a heating history that is information about the first heating region being heated by the first heat generation block corresponding to the first heating region, and the first heating region dissipates heat. Calculated by the control unit based on the heat dissipation history, which is information about the matter.
The second heat storage amount is a heating history that is information about the second heating region being heated by the second heat generation block corresponding to the second heating region, and the second heating region dissipates heat. The image heating device according to any one of claims 1 to 6, wherein the control unit calculates the heat radiation history, which is information about the above. The heating history of the first heating region is calculated by the control unit according to at least one of the control target temperature of the first heat generation block and the electric power supplied to the first heat generation block.
The heating history of the second heating region is calculated by the control unit according to at least one of the control target temperature of the second heat generation block and the electric power supplied to the second heat generation block. The image heating device according to claim 7. The control target temperature of the first heating block in the case of heating the second recording material, and the concentration of the first image portion of the image of the first recording material, wherein the second recording medium the nip The image heating device according to claim 8, wherein the image heating device is calculated according to the first heat storage amount and the second heat storage amount until the portion reaches the unit. The heat dissipation history of the first heating region is calculated by the control unit according to the presence or absence of a recording material passing through the first heating region and at least one of the heat released from the first heating region to the outside air. The image heating device according to claim 7. The image heating device according to claim 10, wherein the heat dissipation history is calculated by the control unit according to the type of the recording material and at least one of the environments in which the image heating device is installed. .. Any of claims 1 to 11, wherein the first heat storage amount and the second heat storage amount are updated by the control unit each time the recording material passes a predetermined number of image heating devices. The image heating device according to the first paragraph. The first heat storage amount and the second heat storage amount are characterized in that they are updated a plurality of times by the control unit between the time when the first recording material reaches the nip portion and the time when the first recording material passes through the nip portion. The image heating device according to any one of claims 1 to 11. The first rotating body is a tubular film, the second rotating body is a roller that contacts the outer peripheral surface of the film, the heater is arranged in the internal space of the film, and the heater and the roller. The film is sandwiched between the two, and the image on the recording material is heated via the film by a nip portion formed between the film and the roller, according to any one of claims 1 to 13. The image heating device according to item 1. An image forming part that forms an image on the recording material,
In an image forming apparatus having a fixing portion for fixing an image formed on a recording material to the recording material.
An image forming apparatus according to any one of claims 1 to 14, wherein the fixing portion is an image heating apparatus.

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