Image forming system

Abstract

To provide an image forming apparatus that can perform a fixing operation according to a fixing unit mounted thereon.SOLUTION: An image forming system comprises an apparatus main body including an image forming section that forms an image on a recording material, and a control section that controls a fixing operation to fix the image formed on the recording material. The apparatus main body can be selectively mounted with a first fixing unit including a first heater and a first number of first temperature detection elements detecting the temperature of the first heater, and a second fixing unit including a second heater different from the first heater and a second number (smaller than the first number) of second temperature detection elements detecting the temperature of the second heater. When the first fixing unit is mounted, the control section controls the fixing operation based on first temperature information detected by the first temperature detection elements, and when the second fixing unit is mounted, controls the fixing operation based on second temperature information detected by the second temperature detection elements.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as an electrophotographic copying machine or printer. The present invention also relates to an image heating apparatus such as a gloss imparting apparatus that improves the glossiness of a toner image by reheating the toner image fixed on a fixing device or recording material mounted on the image forming apparatus. [Background Art]

[0002] In an image heating apparatus such as a fixing device mounted in an image forming apparatus such as a copying machine or a printer, when continuously printing on a recording material (small-size paper) having a narrower width than the maximum size recording material (large-size paper) that can be passed through the image forming apparatus, temperature rise in non-sheet passing areas may occur. The temperature rise in non-sheet passing areas refers to a phenomenon in which the temperature in an area through which the recording material does not pass gradually increases in the width direction orthogonal to the conveyance direction of the recording material (the longitudinal direction of the heater). If the temperature of this non-sheet passing portion becomes excessively high, damage may be caused to various components in the apparatus. Therefore, Patent Document 1 proposes an image forming apparatus in which the fixing device is formed as a unit, and printing can be performed by replacing the dedicated fixing unit in accordance with the type and size of the recording material used by the user. [Prior Art] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2011-56945 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The image forming apparatus is required to perform a fixing operation in accordance with the type of the mounted fixing unit.

[0005] An object of the present invention is to provide an image forming apparatus capable of performing a fixing operation in accordance with a mounted fixing unit. [Means for Solving the Problem]

[0006] To achieve the above objective, the image forming system of the present invention is The apparatus includes an image forming unit that forms an image on a recording material, A control unit that controls the fixing operation for fixing the image formed on the recording material, An image forming system comprising, The main body of the apparatus can be selectively fitted with a first fixing unit equipped with a first heater and a second fixing unit equipped with a second heater different from the first heater. The first fixing unit is, The first heater has a first number of first temperature sensing elements for detecting the temperature of the first heater, The second fixing unit is, The second heater has a second number of temperature sensing elements, which is fewer than the first number, for detecting the temperature of the second heater. The control unit, When the first fixing unit is installed, the fixing operation is controlled based on the first temperature information detected by the first temperature sensing element. When the second fixing unit is installed, the fixing operation is controlled based on the second temperature information detected by the second temperature sensing element. When the recording material with the largest size in the width direction perpendicular to the transport direction of the recording material passes through the fixing unit, before The control target temperature for the fixing operation, which is set when the first fixing unit is mounted on the main body of the device, is set to a higher temperature than the control target temperature, which is set when the second fixing unit is mounted on the main body of the device. The first heater comprises a plurality of heating blocks, each containing a heating element provided on a substrate. , The aforementioned It has multiple heating blocks that are divided in the width direction and whose heating can be controlled individually. The second heater is a single heating block comprising a heating element provided on a substrate, Note The IZ is characterized by having a single heat-generating block corresponding to the aforementioned size of the largest recording material. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an image forming apparatus capable of performing fixing operations according to the attached fixing unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [Figure 1] Schematic sectional view of an image forming apparatus [Figure 2] Schematic sectional view of fixing device A [Figure 3] Configuration diagram of a heating heater [Figure 4] Schematic sectional view of fixing device B [Figure 5] Configuration diagram of a heating heater [Figure 6] Electric circuit configuration diagram of Embodiment 1 [Figure 7] Electric circuit configuration diagram of Embodiment 1 [Figure 8] Diagram showing temperature transition of the fixing film in Embodiment 1 [Figure 9] Diagram showing temperature transition of the fixing film in Embodiment 1 [Figure 10] Control flow diagram of Embodiment 1 [Figure 11] Electric circuit configuration diagram of Embodiment 2 [Figure 12] Electric circuit configuration diagram of Embodiment 2 [Figure 13] Control flow diagram of Embodiment 2 [Figure 14] Diagram showing temperature transition of the heater in Embodiment 3 [Figure 15] Detailed diagram of the temperature detection means in Embodiment 3 [Figure 16] Control flow diagram of Embodiment 3 DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0009] Hereinafter, with reference to the accompanying drawings, modes for carrying out the present invention will be exemplarily described in detail based on working examples. However, the dimensions, materials, shapes, and relative arrangements of the components described in the present embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. In other words, this is not intended to limit the scope of the present invention to the following embodiments.

[0010] (Embodiment 1) [Configuration of the image forming apparatus] Figure 1 is an exemplary configuration diagram of an electrophotographic image forming apparatus in this embodiment. Examples of image forming apparatuses to which the present invention can be applied include photocopiers and printers using electrophotographic or electrostatic recording methods. Here, we will describe the case where the present invention is applied to a laser printer that forms an image on a recording material P using an electrophotographic method. In this embodiment, a color laser printer using so-called tandem type four-color (yellow (Y), magenta (M), cyan (C), black (K)) toners is used as an example, but the types of image forming apparatuses to which the present invention can be applied are not limited to this. For example, the present invention can also be applied to a monochrome printer equipped with a single image forming unit.

[0011] The image forming apparatus 100 comprises a video controller 120 and a control unit 113. The video controller 120 is an acquisition unit that acquires image information formed on a recording material, and receives and processes image information and print instructions transmitted from an external device such as a host computer. The control unit 113 is connected to the video controller 120 and controls each part of the image forming apparatus in accordance with instructions from the video controller 120.

[0012] The image forming apparatus 100 has image forming stations SY, SM, SC, and SK as image forming units for each color. For example, the image forming station SY for yellow consists of a process cartridge 101Y, an intermediate transfer belt 103, and a primary transfer roller 105Y located on the opposite side of the process cartridge 101Y via the intermediate transfer belt 103. The intermediate transfer belt 103 rotates in the direction of arrow A in the figure, and each image forming station SY, SM, SC, and SK is arranged in line with the rotation direction of the intermediate transfer belt 103 and is substantially the same except for the different colors it forms. Therefore, unless otherwise specified, the subscripts Y, M, etc., are used below to indicate that an element is provided for one of the colors. C and K will be omitted, and the explanation will be given in a general manner.

[0013] The process cartridge 101 has a photosensitive drum 104 as an image carrier. The photosensitive drum 104 is driven to rotate clockwise by a drive means (not shown). The charging roller 106 is uniformly charged on the surface of the photosensitive drum 104 by applying a high voltage from a high voltage power supply (not shown). Next, the scanner unit 107, acting as an exposure means, irradiates the photosensitive drum 104 with a laser based on image information input to the video controller 120, forming an electrostatic latent image on the surface of the photosensitive drum 104. The developing roller 108, acting as a developer supply means, rotates counterclockwise by a drive means (not shown), and the charged toner, acting as a developer coated on its surface, adheres along the electrostatic latent image on the surface of the photosensitive drum 104, causing the electrostatic latent image to become a visible image. Hereinafter, the visible image formed by the toner will be referred to as the toner image (toner image). The base layer of the photosensitive drum 104 is grounded, and a voltage opposite to that of the toner is applied to the primary transfer roller 105 by a high voltage power supply (not shown). Therefore, a transfer electric field is formed at the nip between the primary transfer roller 105 and the photosensitive drum 104, and the toner image is transferred from the photosensitive drum 104 to the intermediate transfer belt 103.

[0014] As shown in Figure 1, the intermediate transfer belt 103 rotates in the direction of arrow A, forming and transporting the toner images generated at each color image station S on the intermediate transfer belt 103. The paper feed cassette 109 is loaded with recording material P. When the video controller 120 receives a print command from an external device, the image forming apparatus 100 feeds the recording material P with the feed roller 102 and transports it toward the intermediate transfer belt 103. The recording material P is transported via the registration roller pair 114 to the contact nip formed between the secondary transfer roller 110 and the secondary transfer opposing roller 111 (intermediate transfer belt 103) at a predetermined timing. Specifically, it is transported at the timing when the leading edge of the toner image on the intermediate transfer belt 103 and the leading edge of the recording material P overlap. While the recording material P is being transported between the secondary transfer roller 110 and the secondary transfer opposing roller 111, a voltage with the opposite polarity to the toner is applied to the secondary transfer roller 110 from a power supply (not shown). Since the secondary transfer opposing roller 111 is grounded, a transfer electric field is formed between the secondary transfer roller 110 and the secondary transfer opposing roller 111. This transfer electric field transfers the toner image from the intermediate transfer belt 103 to the recording material P. After the recording material P passes through the nip between the secondary transfer roller 110 and the secondary transfer opposing roller 111, it undergoes heating treatment using the heat of a heater and pressurization treatment by the fixing nip in the fixing device 200. As a result, the toner image on the recording material P is fixed to the recording material P. After that, the recording material P is transported to the output tray 115, and the image formation process is completed.

[0015] The control unit 113 has a storage unit that stores the temperature control program for the fixing device 200.

[0016] In this embodiment, the image formation operation is defined as the combined operation of forming a fixed image on the recording material, that is, the operation of forming an unfixed toner image on the recording material P by each image station and the operation of fixing the toner image to the recording material P by the fixing device 200.

[0017] In this embodiment, an image forming apparatus with a maximum paper feed width of 216 mm in the width direction perpendicular to the transport direction of the recording material P is used, making it possible to print recording material in letter size (216 mm x 279 mm).

[0018] The image forming apparatus 100 in this embodiment is configured to allow selective attachment of one of several types of fixing devices (fixing units) 200, each having a different configuration (type), to the main body of the apparatus. In this embodiment, two types of fixing devices 200 (fixing unit A and fixing unit B) will be described, but three or more types of fixing devices 200 may be configured to be detachable.

[0019] [Configuration of Fuser Unit A] Figure 2 is a cross-sectional view of the first fuser, fuser A (first fuser unit). Fuser A includes a fuser film 202 as an endless belt, a heater 300 that contacts the inner surface of the fuser film 202, a pressure roller 208 that forms a fuser nip portion N together with the heater 300 via the fuser film 202, and a metal stay 204.

[0020] The fixing film 202 is a tubular, multilayer heat-resistant film, and can use a heat-resistant resin such as polyimide with a thickness of about 50 to 100 μm, or a metal such as stainless steel with a thickness of about 20 to 50 μm, as the base layer. In addition, a release layer is formed on the surface of the fixing film 202 to prevent toner adhesion and ensure separation from the recording material P. The release layer is formed by coating with a heat-resistant resin with excellent release properties, such as tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), with a thickness of about 10 to 50 μm. Furthermore, especially in devices that form color images, to improve image quality, a heat-resistant rubber such as silicone rubber with an elastic layer of about 100 to 400 μm in thickness and a thermal conductivity of about 0.2 to 3.0 W / m·K may be provided between the base layer and the release layer. In this example, a 60 μm thick polyimide is used as the base layer, a 300 μm thick silicone rubber as the elastic layer, and a 30 μm thick PFA as the release layer, from the viewpoint of thermal responsiveness, image quality, and durability.

[0021] 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 a 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 that guides the rotation of the fixing film 202. The metal stay 204 receives an applied pressure (not shown) and biases the heater holding member 201 toward the pressure roller 208. The pressure roller 208 rotates in the direction of arrow R1 by receiving power from the motor 30. As the pressure roller 208 rotates, the fixing film 202 follows and rotates in the direction of arrow R2. By applying heat to the fixing film 202 while the recording material P is held and conveyed at the fixing nip section N, the unfixed toner image on the recording material P is fixed.

[0022] The heater 300 is a heater that is heated by a heating element provided on a ceramic substrate 305. The heater 300 has a surface protection layer 308 provided on the side of the fixing nip portion N and a surface protection layer 307 provided on the opposite side of the fixing nip portion N. Multiple electrodes (electrode E3 is shown here as a representative) and electrical contacts (electrical contact C3 is shown here as a representative) are provided on the opposite side of the fixing nip portion N, and power is supplied from each electrical contact to each electrode.

[0023] [Heater configuration of fuser unit A] Figure 3 shows a diagram of the heater 300 of the fuser A. Figure 3(A) shows a cross-sectional view at the transport reference position X shown in Figure 3(B). The transport reference position X is defined as the reference position when transporting the recording material P. In this embodiment, the recording material P is transported so that its central part in the width direction passes through the transport reference position X.

[0024] The alumina substrate 305 has dimensions of 230 mm in the longitudinal direction, 8 mm in the width direction, and 1 mm in thickness. A first conductor 301 (301a, 301b) and a second conductor 303 are provided on the back surface of the substrate 305. The first conductor 301 is provided on the substrate 305 along the longitudinal direction of the heater 300. The second conductor 303 (303-3 at the transport reference position X) is provided on the substrate 305 at different positions in the short direction of the heater 300 from the first conductor 301, along the longitudinal direction of the heater 300. The first conductor 301 is separated into a conductor 301a located upstream in the transport direction of the recording material P and a conductor 301b located downstream.

[0025] Furthermore, the heater 300 is provided between the first conductor 301 and the second conductor 303, and has a heating element 302 that generates heat through the power supplied via the first conductor 301 and the second conductor 303. In this embodiment, the heating element 302 is separated into a heating element 302a (302a-3 at the transport reference position X) located upstream in the transport direction of the recording material P, and a heating element 302b (302b-3 at the transport reference position X) located downstream. Also, an insulating (glass in this embodiment) surface protection layer 307 is provided on the back surface layer 2 of the heater 300, covering the heating element 302, the first conductor 301, and the second conductor 303 (303-3 at the transport reference position X), avoiding the electrode portion E (E3 at the transport reference position X). In addition, the conductor 301, the conductor 303, and the heating element 302 are all screen printed to a thickness of 10 μm.

[0026] Figure 3(B) shows plan views of each layer of the heater 300. Multiple heating blocks, each consisting of a first conductor 301, a second conductor 303, and a heating element 302, are provided in the longitudinal direction of the heater 300 on the back layer 1 of the heater 300. In this embodiment, the heater 300 has a total of five heating blocks HB1 to HB5 in the longitudinal direction of the heater 300. The heating region extends from the left end of heating block HB1 in the figure to the right end of heating block HB5 in the figure, and its length is 220 mm. Heating blocks HB1 to HB5 are each composed of heating elements 302a-1 to 302a-5 and heating elements 302b-1 to 302b-5, which are formed symmetrically in the short direction of the heater 300. The first conductor 301 in the back layer 1 is composed of a conductor 301a that connects to the heating elements (302a-1 to 302a-5) and a conductor 301b that connects to the heating elements (302b-1 to 302b-5). Similarly, the second conductor 303 is divided into five conductors 303-1 to 303-5 to correspond to the five heating blocks HB1 to HB5.

[0027] Electrodes E1 to E5 are electrodes used to supply power to the heating blocks HB1 to HB5 via conductors 303-1 to 303-5, respectively. Electrodes E8-1 and E8-2 are electrodes used to connect to a common electrical contact used to supply power to the five heating blocks HB1 to HB5 via conductors 301a and 301b. In this embodiment, electrodes E8-1 and E8-2 are provided at both ends in the longitudinal direction, but for example, a configuration in which only electrode E8-1 is provided on one side is also possible, or separate electrodes may be provided upstream and downstream in the recording material transport direction.

[0028] Furthermore, the surface protective layer 307 of the back layer 2 of the heater 300 is formed except for the locations of electrodes E1 to E5, E8-1, and E8-2. With this configuration, electrical contacts C1 to C5, C8-1, and C8-2 can be connected to each electrode from the back layer side of the heater 300, and power can be supplied from the back layer side of the heater 300. In addition, the power supplied to at least one of the heating blocks and the power supplied to the other heating blocks can be controlled independently. By providing electrodes on the back surface of the heater 300, it is not necessary to perform wiring with conductive patterns on the substrate 305, so the width of the substrate 305 in the short direction can be shortened. As a result, it is possible to reduce the material cost of the substrate 305 and shorten the start-up time for the heater 300 to rise in temperature by reducing the heat capacity of the substrate 305. Note that electrodes E1 to E5 are provided within the region where the heating element is provided in the longitudinal direction of the substrate.

[0029] The sliding surface layer 2 on the sliding surface side (the side that contacts the fixing film) of the heater 300 has a sliding surface protection layer 308 (glass in this embodiment). The surface protection layer 308 is provided in at least the region that slides with the fixing film 202, except for both ends of the heater 300. At both ends of the heater 300 that are not covered by the surface protection layer 308, electrical contacts are provided on conductors ET1-1 to ET1-3, ET2-4 to ET2-5 for detecting the resistance value of the thermistor, and on the common conductors EG1 and EG2 of the thermistor. The sliding surface layer 1 has a thermistor T1, which is a temperature sensing element for detecting the temperature of each heating block HB1 to HB5 of the heater 300, formed thinly on a substrate from a material having PTC characteristics or NTC characteristics (NTC characteristics in this embodiment). ~T5 is installed. Since all of the heat-generating blocks HB1~HB5 have thermistors, the temperature of all heat-generating blocks can be detected by detecting the resistance value of the thermistors.

[0030] As shown in Figure 3(C), the retaining member 201 of the heater 300 is provided with holes for connecting electrodes E1, E2, E3, E4, E5, E8-1, and E8-2 and electrical contacts C1-C5, C8-1, and C8-2. The aforementioned electrical contacts C1-C5, C8-1, and C8-2 are provided between the stay 204 and the retaining member 201. The electrical contacts C1-C5, C8-1, and C8-2 that contact electrodes E1-E5, E8-1, and E8-2 are electrically connected to the electrode portion of the heater by methods such as spring biasing or welding. Each electrical contact is connected to the control circuit 600 of the heater 300, which will be described later, via conductive materials such as cables or thin metal plates provided in the space between the stay 204 and the retaining member 201. Furthermore, the electrical contacts provided on the conductors ET1-1 to ET1-3, ET2-4 to ET2-5 for detecting the thermistor's resistance value, and on the common conductors EG1 and EG2 of the thermistor, are also connected to the control circuit 600, which will be described later.

[0031] [Configuration of Fuser Unit B] Figure 4 is a cross-sectional view of fuser B (second fuser unit), which is the second fuser used in this embodiment. The only difference from fuser A in Figure 2 is the heater; the other components are the same and will not be explained. Heater 400 of fuser B is heated by a heating element provided on a ceramic substrate 401. Heater 400 has a surface protection layer 402 on the side of the fuser nip N. An electrode and electrical contacts (not shown) are provided on the opposite side of the fuser nip N, and power is supplied from the electrical contacts to the electrode. A detailed explanation of heater 400 is given in Figure 5. In addition, a thermistor 212, which acts as a temperature sensing element to detect the temperature of heater 400, is in direct contact with heater 400.

[0032] [Heater configuration of fuser unit B] Figure 5 shows the configuration diagram of the heater 400 of fuser unit B. Figure 5(A) is a cross-sectional view of the heater 400. The alumina substrate 401 has dimensions of 230 mm in the longitudinal direction, 8 mm in the width direction, and 1 mm in thickness, and the heating element 403 is screen printed with a thickness of 10 μm. In addition, a protective layer 402 made of glass is screen printed with a thickness of 50 μm. Figure 5(B) is a plan view of the heater 400 as seen from the fuser nip N side. Conductive patterns 404 and 405 as electrodes are formed at the edges of the alumina substrate 401. The heating element 403 consists of two heating elements connected in series via a conductive pattern 406. The heating element 403 is heated by supplying power to the conductive patterns 404 and 405.

[0033] [Heater control circuit configuration] Figure 6 is a circuit diagram of the fuser control circuit in this embodiment, and is a circuit diagram when fuser A is installed in the image forming apparatus. The area enclosed by the dashed line in Figure 6 shows the circuit diagram of fuser A. The CPU 420 is a component of the control unit 113 of the image forming apparatus and is responsible for driving the control circuit. Power control from the commercial AC power supply 422 connected to the image forming apparatus 100 to the heater 300 is performed by energizing / cutting off semiconductor switching elements, triacs 411 to 415. Triacs 411 to 415 operate according to FUSER1 to FUSER5 signals from the CPU 420, respectively. The drive circuits for triacs 411 to 415 are omitted from the diagram. The control circuit of the heater 300 has a circuit configuration that allows for independent control of five heat-generating blocks HB1 to HB5 by five triacs 411 to 415.

[0034] The zero-cross detection unit 421 is a circuit that detects the zero-crossing of the AC power supply 422 and outputs a ZEROX signal to the CPU 420. The ZEROX signal is transmitted via triacs 411-4 It is used for detecting the timing of phase control and wavenumber control, among other things.

[0035] Next, the method for detecting the temperature of heater 300 will be explained. The temperature detected by thermistors T1 to T5 is obtained by the AD converter 423, which detects the divided voltage between thermistors T1 to T5 and resistors 451 to 455 as Th1 to Th5 signals. The AD converter 423 discretizes the analog voltage signals of Th1 to Th5 and converts them into digital signals, and transmits this digital information as temperature information to the CPU 420 via serial communication.

[0036] In the internal processing of CPU420, the power to be supplied is calculated based on the set temperature of each heat-generating block and the temperature detected by the thermistor, for example, using PI (proportional-integral) control. Furthermore, the power to be supplied is converted into a control level for the phase angle (phase control) and wavenumber (wavenumber control), and triacs 411 to 415 are controlled according to these control conditions. Relays 430 and 440 are used as means of cutting off power to heater 300 if it overheats due to a malfunction or other reason.

[0037] Figure 7 is a circuit diagram of the fuser control circuit in this embodiment, and is a circuit diagram when fuser B is installed in the image forming apparatus. The area enclosed by the dashed line in Figure 7 shows the circuit diagram of fuser B. Power control of the heater 400 of fuser B is performed by energizing / cutting off the triac 411. The triac 411 operates according to the FUSER1 signal from the CPU 420. Since the heater 400 has only one heating element 403, triacs 412 to 415 are not connected to fuser B (they are isolated). The temperature of the heater 400 is detected by thermistor 212. The temperature detected by thermistor 212 is detected by the AD converter 423 as the Th1 signal, which is the voltage division between the thermistor 212 and the resistor 456. The AD converter 423 discretizes the analog voltage signal of Th1 and converts it into a digital signal, and transmits the digital information as temperature information to the CPU 420 via serial communication. The rest of the control circuit configuration is the same as in Figure 6, so we will omit the explanation.

[0038] [Overview of Heater Control Method] In this embodiment, the image forming apparatus performs image forming operations with different control content depending on the type of fixing unit mounted on the apparatus body.

[0039] The heater 300 of the first fixing unit, fuser A, is divided in the width direction perpendicular to the transport direction of the recording material P, and has multiple heating blocks, each capable of individually controlling heat generation. In contrast, the heater 400 of the second fixing unit, fuser B, has a configuration in which the width corresponds to the size of the largest recording material. In fuser A, the control target temperature is set individually for each of the multiple heating blocks according to the size of the recording material P passing through fuser A. For example, when the largest recording material passes through fuser A, the control target temperature may be set to the same temperature for each of the multiple heating blocks. For example, when fixing a recording material that is narrower than the maximum size, the control target temperature of the heating block at the end in the width direction may be set to a lower temperature than the control target temperature of the heating block further inside in the width direction than that heating block. The specific control details will be explained below.

[0040] When fuser A is installed, the power supplied to each of the five heating blocks HB1 to HB5 of heater 300 is optimally controlled and selectively heated according to the printing conditions sent from an external device (not shown), such as a host computer. The power supplied to each of the heating blocks HB1 to HB5 is determined by the control unit 113 by referring to the control target temperature (hereinafter, control temperature TgtA) as a heating parameter for each heating block HB1 to HB5.

[0041] The thermistors T1 to T5 corresponding to the heat-generating blocks HB1 to HB5 are set so that their detected temperatures are equal to the control temperature TgtA set for each heat-generating block HB1 to HB5. Temperature control is implemented.

[0042] When the fuser B is installed in the image forming apparatus, power is supplied to the heating element 403 of the heater 400 according to the printing conditions sent from an external device (not shown), such as a host computer. The power supplied is determined by the control unit 113 by referring to the control target temperature (hereinafter, control temperature TgtB) as a heating parameter for the heating element 403.

[0043] Furthermore, the temperature is controlled so that the temperature detected by the thermistor 212 is equal to the control temperature TgtB set for the heater 400.

[0044] Here, the control temperature TgtA of fuser A and the control temperature TgtB of fuser B will be different values. This is because in fuser A, thermistors T1 to T5 are installed between the ceramic substrate 305 and the fixing film 202, whereas in fuser B, they are installed on the back side of the ceramic substrate 402 (opposite side from the fixing film). In other words, when the fixing nip section N is set to the optimal temperature for heating and fixing the unfixed toner of the recording material P, thermistors T1 to T5 in fuser A are set close to the fixing nip section N, so a relatively high temperature is detected. On the other hand, even if the temperature of the fixing nip section N is the same, thermistor 212 in fuser B is installed far from the fixing nip section N, so a relatively low temperature is detected. For this reason, in this embodiment, the control temperature TgtA is set to a higher temperature than the control temperature TgtB.

[0045] [Controlling printing speed for each paper size] In this embodiment of the image forming apparatus, the types of recording materials that can be fed through include Letter paper (216 mm wide) as the widest recording material (large size paper), and Executive paper (184 mm wide), which is narrower than Letter paper. When printing multiple sheets of Letter paper and Executive paper in succession, the control of the number of sheets that pass through the fuser per unit time, or the number of prints per minute (hereinafter referred to as throughput), will be described.

[0046] When fuser A is installed in the image forming apparatus, it is possible to print on both Letter paper and Executive paper at the same throughput by changing the control temperature of the heating blocks HB1 to HB5 for each paper size. This is because, in the case of Letter paper, the paper passes through the entire length of heating blocks HB1 to HB5, so good fixing can be obtained by setting all heating blocks to the same control temperature. On the other hand, in the case of Executive paper, the area through which the paper passes is heating blocks HB2 to HB4 (the length of heating blocks HB2 to HB4 is 188 mm), and heating blocks HB1 and HB5 are non-paper-passing areas. If the control temperature of heating blocks HB1 to HB5 were all set to the same temperature, the temperature of the heating blocks HB1 and HB5 would be higher than that of other areas, potentially exceeding the heat resistance temperature of the fixing film, etc. Therefore, in this embodiment, the control temperature of heating blocks HB1 and HB5 (first heating blocks) when Executive paper is passed through is set to a lower temperature than the control temperature of heating blocks HB2 to HB4 (second heating blocks). By doing this, it becomes possible to print at the same throughput as Letter paper, as mentioned above.

[0047] Table 1 shows the control temperature (predetermined control target temperature) of the heat-generating block when printing Letter paper and Executive paper at a throughput of 50 ppm (pages per minute).

[0048] [Table 1] Control temperature of fuser A TIFF0007919871000001.tif17153

[0049] Figure 8 shows the temperature changes of the fixing film at this time. Figure 8(A) shows the case when Letter paper is printed, and all heating blocks HB1 to HB5 are in the paper-feed area. The surface temperature of the fixing film in the paper-feed area remains constant at 170°C and is maintained below the heat resistance temperature. On the other hand, Figure 8(B) shows the case when Executive paper is printed, and the film temperature in the paper-feed area, shown by the solid line, is the same as in Figure 8(A). Heating blocks HB1 and HB5 are in the non-paper-feed area, and as a result of setting the control temperature of heating blocks HB1 and HB5 to a low temperature of 180°C, the film temperature in the non-paper-feed area, shown by the dashed line, remains at a low temperature in the initial stages of printing. However, due to the effect of the temperature rise in the non-paper-feed area, the temperature gradually rises and eventually becomes about the same as the film temperature in the paper-feed area. Furthermore, the fixing film temperature is maintained below the heat resistance temperature in all areas.

[0050] When fuser B is installed in the image forming apparatus, the target temperature of heater 400 is set to a single temperature regardless of the paper size.

[0051] Table 2 shows the controlled temperature of the heater 400 and the throughput set for each paper size when printing on Letter paper and Executive paper.

[0052] [Table 2] Control temperature and throughput of fuser unit B TIFF0007919871000002.tif22170

[0053] As mentioned above, in the paper feeding area, the control temperature of fuser A is set higher than the control temperature of fuser B. For example, when printing Executive paper, the control temperatures of the heat-generating blocks HB2 to HB4 of fuser A, which are in the paper feeding area, are set to a higher temperature (220°C) than the control temperature of fuser B (200°C). On the other hand, when printing Executive paper, the control temperatures of the heat-generating blocks HB1 and HB5 of fuser A, which are in the non-paper feeding area, are set to a lower temperature (180°C) than the control temperature of fuser B (200°C).

[0054] Figure 8(A) shows the temperature change of the fuser film when printing Letter paper at 50 ppm, and it is exactly the same as the temperature change of fuser A. Next, when printing Executive paper at 20 ppm, the transport speed of the recording material is set to the same speed as for Letter paper, but the interval at which the recording material is supplied is extended to process 20 sheets per minute. Also, the control temperature of heater 400 is set to the same temperature as for Letter paper. By setting the throughput to 20 ppm, the time when the recording material is not held in the fuser nip section N (hereinafter referred to as "between sheets") becomes longer. During the "between sheets" period, the heat generated by the heater is not supplied to the paper, so the heater temperature can be controlled to 200°C with less power. Therefore, during the "between sheets" period, less power is supplied even in the non-feeding section, which suppresses the temperature rise of the non-feeding section.

[0055] Figure 9(A) shows the temperature changes of the fixing film at this time. The fixing film temperature in the paper-feeding area, shown by the solid line, remained constant at 170°C, while the fixing film temperature in the non-feeding area remained constant in the non-image area. The effects of the temperature increase are being observed. However, because the throughput is set to 20 ppm, the rate of temperature increase is being suppressed, and thus the temperature is being kept below the heat resistance temperature of the fixing film.

[0056] Figure 9(B) shows the temperature change of the fuser film when Executive paper is printed at 50 ppm. In this case, the throughput is high, so the time between sheets of paper is short, and the amount of power that must be supplied to the paper per unit time increases. On the other hand, in the non-paper-passing area, no paper passes through, so all the supplied power becomes energy to heat the fuser, causing the fuser film temperature to rise. Therefore, when printing small-sized paper with fuser B, it is effective to reduce the throughput.

[0057] [Method for identifying the fuser unit, and printing operation] Figure 10 is a flowchart of the fuser identification method and print control in this embodiment. In S101, when the power of the image forming apparatus is turned on, the initialization operation of the image forming apparatus begins. During this initialization operation, the CPU 420, acting as a receiver, receives thermistor signals from the AD converter 423 in the fuser via serial communication. Next, in S102, the CPU 420, acting as an acquisition means for acquiring the number of thermistors provided in the fuser unit mounted on the main body of the apparatus, analyzes the digital information of the received thermistor signals and counts the number of thermistor signals.

[0058] In this embodiment, the image forming apparatus can be fitted with fuser A and fuser B, and each fuser has a different number of thermistors. Therefore, by the difference in the number of thermistor signals transmitted from the AD converter 423 to the CPU 420, it is possible to determine and distinguish the type of fuser unit fitted to the apparatus, that is, whether fuser A or fuser B is fitted to the apparatus. If the number of thermistor signals in S103 is two or more, it is determined in S104 that fuser A is fitted to the image forming apparatus. On the other hand, if the number of thermistor signals in S103 is less than two, it is determined in S105 that fuser B is fitted to the image forming apparatus. The above operations are completed during the initialization operation of the image forming apparatus.

[0059] Next, if a print start request occurs in S106, the print conditions are determined in S107. If the print condition in S107 is large size paper, the process proceeds to S108. In S108, based on the determination result of the fuser installed in the image forming apparatus, if fuser A is installed, the control temperature is set to TgtA (220°C) in S109. On the other hand, if the determination result in S108 is fuser B, the control temperature is set to TgtB (200°C) in S110. Next, if the print condition in S107 is small size paper, the process proceeds to S111.

[0060] In S111, based on the determination result of the fuser installed in the image forming apparatus, if fuser A is installed, the optimal control temperature is set for each heating block in S112 according to the paper size to be printed. Specifically, the heating blocks HB2 to HB4, which are the paper feeding sections, are set to 220°C, and the heating blocks HB1 and HB5, which are not the paper feeding sections, are set to 180°C. On the other hand, if the determination result in S111 is fuser B, the control temperature is set to TgtB (200°C) in S113, and the throughput is set to the second throughput of 20 ppm in S115. If the process transitions to any of S109, S110, or S112, the throughput is set to the first throughput of 50 ppm in S114. Finally, printing is performed in S116.

[0061] As explained above, in this embodiment, in an image forming apparatus capable of being fitted with multiple types of fusers, good fixing performance can be obtained by changing the heater temperature control and throughput control according to the fuser fitted by the user. Furthermore, by automatically detecting the type of fuser, the optimal fixing control temperature and throughput are set according to the paper size set by the user. The process can be executed. Furthermore, by using the thermistor signal, which is an essential component of the fuser, a dedicated device specifically for identifying the installed fuser becomes unnecessary.

[0062] In this embodiment, control of the fixing operation of the fuser A is exemplified by control according to the size of the recording material. However, control may also be performed to adjust the target temperature for each heat-generating block according to the image information formed on the recording material. That is, control is performed to lower the temperature of the non-image area, where no image is formed, compared to the temperature of the image area. Such control can also suppress edge heating and reduce power consumption.

[0063] Furthermore, in this embodiment, two types of fusers have been exemplified as types of fuser units that can be attached to the main body of the device, but the number of types may be three or more. In an image forming system in which multiple fuser units can be selectively replaced in this manner, as shown in Figure 7, the number of connection points on the main body of the device that are electrically connected to the thermistors of the fuser units should be at least the same as the maximum number of thermistors provided in a single fuser unit.

[0064] (Example 2) The image forming apparatus according to Embodiment 2 of the present invention can be fitted with multiple types of fusers with different configurations, and in this embodiment, a specific thermistor signal is used as a method for identifying the fitted fuser. Furthermore, the image forming apparatus of Embodiment 2 can be fitted with fuser A shown in Figure 2 and fuser B shown in Figure 4, similar to Embodiment 1. The configuration of the image forming apparatus, fuser, and heating heater in Embodiment 2 is the same as in Embodiment 1, and therefore its description is omitted.

[0065] [Heater control circuit configuration] Figure 11 is a circuit diagram of the fuser control circuit in this embodiment, showing the circuit when fuser A is installed in the image forming apparatus. The area enclosed by the dashed line in Figure 11 shows the circuit diagram of fuser A.

[0066] The only difference from Example 1 is the method for detecting the temperature of the heater 300; the other circuit configurations are the same as in Example 1, so a detailed explanation is omitted. The temperature detected by thermistors T1 to T5 is directly connected to the CPU 420 as the Th1 to Th5 signals, which are obtained by dividing the voltage between thermistors T1 to T5 and resistors 451 to 455. In other words, the CPU 420 is individually connected to the multiple thermistors T1 to T5 provided in the fuser A, thereby forming multiple temperature detection circuits corresponding to each thermistor. The output values ​​of thermistors T1 to T5 are individually output to the CPU 420 via these multiple temperature detection circuits. The CPU 420 discretizes the analog voltage signals of Th1 to Th5 and converts them into digital signals, which are used for calculating the temperature control of the heater 300.

[0067] Figure 12 is a circuit diagram of the fuser control circuit in this embodiment, showing the circuit when fuser B is installed in the image forming apparatus. The area enclosed by the dashed line in Figure 12 shows the circuit diagram of fuser B.

[0068] The difference from Example 1 lies in the method of detecting the temperature of the heater 400; the other circuit configurations are the same as in Example 1, so their explanation will be omitted. The temperature detected by the thermistor 212 is expressed as the Th1 signal, which is the voltage division between the thermistor 212 and the resistor 456, while Th2 to Th5 are directly connected to the CPU 420 in a grounded state. That is, the CPU 420 is configured as a first temperature detection circuit connected to the thermistor 212 provided in the fuser B, and a second temperature detection circuit that outputs a value equivalent to the ground potential when there is no temperature detection element to connect to. The CPU 420 discretizes the analog voltage signals of Th1 to Th5 and converts them into digital signals, which are used for calculating the temperature control of the heater 400. Since the signals of Th2 to Th5 are grounded, they are detected as 0[V] by the CPU 420. In addition, since the thermistor in this embodiment has NTC characteristics, when the temperature of the heater 400 rises, the resistance of the thermistor 212 This becomes smaller. Therefore, in the circuit shown in Figure 12, since resistor 456 (fixed value) and thermistor 212 are connected in series, the potential of Th1 decreases as the temperature of heater 400 increases.

[0069] [How to identify a fuser unit] When fuser A is installed in the image forming apparatus of this embodiment, the resistance values ​​of thermistors T1 to T5 are greater than 0[Ω] regardless of the temperature of heater 300, so the potentials of Th1 to Th5 are greater than 0[V]. On the other hand, when fuser B is installed, the resistance value of thermistor 212 is greater than 0[Ω] regardless of the temperature of heater 400, so the potential of Th1 is greater than 0[V]. However, since Th2 to Th5 are grounded, their potential is 0[V]. Therefore, if the potential of any of the Th2 to Th5 signals is 0[V] in the CPU 420, it can be determined that fuser B is installed in the image forming apparatus. On the other hand, if the potentials of all of the Th2 to Th5 signals are greater than 0[V] in the CPU 420, it can be determined that fuser A is installed.

[0070] Figure 13 is a flowchart of the fuser identification method and print control in this embodiment. When the power of the image forming apparatus is turned on in S101, the initialization operation of the image forming apparatus begins. During this initialization operation, in S202, the CPU 420 acquires the voltage of the thermistor signal connected to the fuser. Next, in S203, if the Th2 to Th5 signals among the acquired thermistor signals are all greater than 0[V], the CPU 420 determines in S104 that the installed fuser is fuser A. On the other hand, if the Th2 to Th5 signals are all 0[V] in S203, the CPU 420 determines in S105 that fuser B has been installed in the image forming apparatus. The above operations are completed during the initialization operation of the image forming apparatus. The flowchart from here on is the same as in Embodiment 1, so the explanation is omitted.

[0071] As described above, in this embodiment, an image forming apparatus capable of accommodating multiple types of fusers can automatically identify the fuser installed by the user and set the optimal fuser control temperature and throughput according to the paper size set by the user to execute printing. Furthermore, by using the thermistor signal, which is an essential component for fusers, a dedicated device specifically for identifying the installed fuser is not required.

[0072] (Example 3) In Embodiment 3 of the present invention, the method for distinguishing the installed fuser is to use the difference in the rate of temperature rise detected by the thermistor when the heater is heated. Furthermore, the image forming apparatus in Embodiment 3 can be fitted with fuser A shown in Figure 2 and fuser B shown in Figure 4, similar to Embodiment 1. The configuration of the image forming apparatus, fuser, and heating heater in Embodiment 3 is the same as in Embodiment 1, and therefore, a detailed explanation is omitted.

[0073] Figure 14 shows the temperature profiles detected by the thermistors in heater 300 of fuser A and heater 400 of fuser B when a constant power is applied to them. When the heater temperature reaches the control temperature from room temperature after a constant power is applied, it switches to PI control. Although the power applied to fuser A and fuser B is the same, the heating rate detected by the thermistor of fuser A is faster. The reason for this will be explained. The thermistors in fuser A are thermistors T1 to T5 shown in Figure 3, and are screen printed on a ceramic substrate 305 with a thickness of 10 μm and a width of 1 mm. Therefore, thermistors T1 to T5 have a very small heat capacity, so they are highly sensitive to temperature changes and can achieve a fast thermal response. Figure 15 shows a detailed cross-sectional view of the thermistor 212 of fuser B. The thermistor 212 consists of a thermistor element 213 that senses temperature, ceramic paper 214 to hold the thermistor element 213, and a polyimide film 215 as a protective layer on the surface. The thermistor element 213 has a diameter of about 1 mm and its heat capacity is therm The value is larger compared to thermistors T1-T5. Therefore, the thermal response of thermistor 212 is somewhat slower. Due to this difference in thermal response between thermistors T1-T5 and thermistor 212, the heating rate differed as shown in Figure 14. In this embodiment, when the power supplied to the fuser was 900[W], the temperature rise slope α1 of fuser A was 135(°C / sec), and the temperature rise slope α2 of fuser B was 117(°C / sec).

[0074] [How to identify a fuser unit] In this embodiment, the type of fuser installed is determined by the difference in the heating rate when a certain amount of power is supplied to the heater, based on the temperature detected by the thermistor. As an initial operation when the power of the image forming apparatus is turned on, a certain amount of power is supplied to the heater. After a predetermined time has elapsed, the temperature of each thermistor is detected, and if the temperature is above a predetermined threshold, it can be determined that fuser A is installed. On the other hand, if the temperature is below the predetermined threshold, it can be determined that fuser B is installed.

[0075] Figure 16 shows the fuser identification method and print control flowchart in this embodiment. When the power to the image forming apparatus is turned on in S101, the initialization operation of the image forming apparatus begins. During this initialization operation, a certain amount of power (900[W]) is supplied to the heater in S302. Next, in S303, the slope α of the heating curve is calculated from the initial temperature of the thermistor when the power is turned on and the temperature of the thermistor after a predetermined time has elapsed since power was supplied to the heater. If this slope α is 125 (°C / sec) or more, which is a predetermined threshold for the heating rate, it is determined in S104 that the installed fuser is fuser A. On the other hand, if the slope α in S303 is less than 125 (°C / sec), it is determined in S105 that fuser B has been installed in the image forming apparatus. The above operations are completed during the initialization operation of the image forming apparatus. The flowchart from here on is the same as in Embodiment 1, so the explanation is omitted.

[0076] As described above, in this embodiment, an image forming apparatus capable of accommodating multiple types of fusers can automatically identify the fuser installed by the user and set the optimal fuser control temperature and throughput according to the paper size set by the user to execute printing. Furthermore, by using the thermistor signal, which is an essential component for fusers, a dedicated device specifically for identifying the installed fuser is not required. [Explanation of Symbols]

[0077] 100…Image forming apparatus (main unit), 200…Fusing device, 300, 400…Heater, 420…CPU, T1~T5, 212…Thermistor

Claims

1. The apparatus includes an image forming unit that forms an image on a recording material, A control unit that controls the fixing operation for fixing the image formed on the recording material, An image forming system comprising, The main body of the apparatus can be selectively fitted with a first fixing unit equipped with a first heater and a second fixing unit equipped with a second heater different from the first heater. The first fixing unit is, The first heater has a first number of first temperature sensing elements for detecting the temperature of the first heater, The second fixing unit is, The second heater has a second number of second temperature sensing elements, which is fewer than the first number, for detecting the temperature of the second heater. The control unit, When the first fixing unit is installed, the fixing operation is controlled based on the first temperature information detected by the first temperature sensing element. When the second fixing unit is installed, the fixing operation is controlled based on the second temperature information detected by the second temperature sensing element. When the recording material with the largest size in the width direction perpendicular to the transport direction of the recording material passes through the fixing unit, The target temperature for control during the fixing operation, which is set when the first fixing unit is mounted on the main body of the device, is set to a higher temperature than the target temperature for control when the second fixing unit is mounted on the main body of the device. The first heater comprises a plurality of heating blocks, each having a heating element provided on a substrate, and having a plurality of heating blocks that are separated in the width direction and whose heating can be controlled individually. The image forming system is characterized in that the second heater is a single heating block comprising a heating element provided on a substrate, the size of which corresponds to the size of the largest recording material.

2. The control unit, When the first fixing unit is mounted on the main body of the device, The image forming system according to claim 1, characterized in that the control target temperature in the fixing operation is set individually for each of the plurality of heat-generating blocks according to the size of the recording material passing through the first fixing unit.

3. The control unit, When the first fixing unit is mounted on the main body of the device, and the largest recording material of the aforementioned size passes through the first fixing unit, The image forming system according to claim 1 or 2, characterized in that the control target temperature in the fixing operation is set to the same temperature for each of the plurality of heating blocks.

4. The control unit, When the first fixing unit is mounted on the main body of the device, and a recording material smaller in size than the largest recording material passes through the first fixing unit, The image forming system according to any one of claims 1 to 3, characterized in that the target temperature for control during the fixing operation of the first heating block located at the end in the width direction among the plurality of heating blocks is set to a temperature lower than the target temperature for control of the second heating block located inside the first heating block in the width direction.

5. The control unit, When the first fixing unit is mounted on the main body of the device, The image forming system according to claim 4, characterized in that the control target temperature of the second heating block, which is set when a recording material smaller in size than the largest recording material passes through the first fixing unit, and the control target temperature of the second heating block, which is set when the largest recording material passes through the first fixing unit, are set to the same temperature.

6. The control unit, When the second fixing unit is mounted on the main body of the device, and a recording material smaller in size than the largest recording material passes through the second fixing unit, The image forming system according to claim 4 or 5, characterized in that the control target temperature set in the second fixing unit is set to a temperature higher than the control target temperature set in the first heating block in the first fixing unit, and lower than the control target temperature set in the second heating block in the first fixing unit.

7. The image forming system according to claim 1, characterized in that the control unit controls the fixing operation such that the number of recording materials passing per unit time of the plurality of recording materials passing through the fixing unit is different when the first fixing unit is mounted on the main body of the device and when the second fixing unit is mounted on the main body of the device.

8. A device body comprising an image forming unit that forms an image on a recording material, A control unit that controls the fixing operation for fixing the image formed on the recording material, An image forming system comprising, The main body of the apparatus can be selectively fitted with a first fixing unit equipped with a first heater and a second fixing unit equipped with a second heater different from the first heater. The first fixing unit is, The first heater has a first number of first temperature sensing elements for detecting the temperature of the first heater, The second fixing unit is, The second heater has a second number of second temperature sensing elements, which is fewer than the first number, for detecting the temperature of the second heater. The control unit, When the first fixing unit is installed, the fixing operation is controlled based on the first temperature information detected by the first temperature sensing element. When the second fixing unit is installed, the fixing operation is controlled based on the second temperature information detected by the second temperature sensing element. The fixing operation is controlled such that the number of recording materials passing through the fixing unit per unit time differs depending on whether the first fixing unit is mounted on the main body of the device or the second fixing unit is mounted on the main body of the device. When the second fixing unit is mounted on the main body of the device, The number of recording materials that pass through the second fixing unit per unit time is set to be smaller than the number of recording materials that pass through the second fixing unit per unit time when the recording material with the largest size in the width direction perpendicular to the transport direction of the recording materials passes through the second fixing unit. The first heater comprises a plurality of heating blocks, each having a heating element provided on a substrate, and having a plurality of heating blocks that are separated in the width direction and whose heating can be controlled individually. The image forming system is characterized in that the second heater is a single heating block comprising a heating element provided on a substrate, the size of which corresponds to the size of the largest recording material.

Images