Patent Application
20200166876
The present invention relates to an image forming apparatus, such as a printer, a copier and facsimile, using an electrophotographic system or an electrostatic recording system. The present invention also relates to an image heating apparatus, such as a glossing apparatus to improve the gloss of a toner image, by reheating a toner image fixed to a fixing unit or a recording material in the image forming apparatus.
In an image heating apparatus, such as a fixing unit and a glossing apparatus, used for an electrophotographic image forming apparatus (hereafter “image forming apparatus”), such as a copier and a printer, a system to selectively heat an image portion formed on a recording medium was proposed for power saving (Japanese Patent Application Publication H06-95540). According to this system, a plurality of divided heating regions are set in a direction corresponding to the longer direction of the heater (hereafter “longer direction”), which is orthogonal to the transporting direction of the recording material, and a plurality of heating elements which heats the heating regions respectively, are disposed in the longer direction. Then based on the image information on the image that is formed in each heating region, the heating value of the corresponding heating element is controlled. For example, the control temperature for each heating region, where no image exists (hereafter “non-image heating portion”), is set to be lower than the control temperature for a heating region where an image is included (hereafter “image heating portion”).
In the configuration having a plurality of heating regions which are divided in the longer direction, a temperature gradient is generated in the vicinity of a boundary position between a non-image heating portion and an image heating portion adjacent thereto, because of the difference between the control temperatures of these portions. This may generate a fixing failure and a drop in gloss in the vicinity of the edge of the image on the boundary position side.
To solve this problem, Japanese Patent Application Publication No. 2018-4938 discloses an image forming apparatus that changes the temperature of the image heating portion adjacent to the boundary position in accordance with the distance between the boundary position and the edge of the image in the longer direction. This content will be described with reference to
The control method of Japanese Patent Application Publication No. 2018-4938, however, has the following problem. This problem is related to the method of calculating the position information of the image.
In Japanese Patent Application Publication No. 2018-4938, the image A exists in the region of 903-1 and the image B exists in the region of 903-2, as illustrated in
As indicated by the solid line in
It is an object of the present invention to provide a technique that implements a further power supply saving effect in a configuration where heating control is performed for a plurality of heating regions independently by a plurality of heating elements disposed in the longer direction, while preventing the generation of a fixing failure and a drop in gloss in a vicinity of the edges of the image.
To achieve the above object, an image heating apparatus that heats an image formed on a recording material according to the present invention includes:
a heater including a plurality of heating elements which are arranged in a direction orthogonal to a transporting direction of a recording material;
a control portion capable of individually controlling power to be supplied to the plurality of heating elements so as to individually control the temperature of a plurality of heating regions which are heated by the plurality of heating elements; and
an acquisition portion that acquires information on an image formed on a recording material, wherein
the control portion
divides a region of a recording material, on which an image is formable, into a boundary region and a non-boundary region which are regions divided in a direction orthogonal to the transporting direction so as to correspond to the plurality of heating elements,
the boundary region is a region which includes a boundary between one heating element, out of the plurality of heating elements, and an adjacent heating element thereof and overlap with the one heating element and the adjacent heating element by a predetermined range in the direction orthogonal to the transporting direction, and
the non-boundary region is a region that overlaps with the one heating element in a range other than the boundary region, wherein
a control target temperature of a heating region that is heated by the one heating element is set to a higher temperature of a first temperature based on information corresponding to the boundary region out of the image information, and a second temperature based on information corresponding to the non-boundary region out of the image information.
To achieve the above object, an image forming apparatus according to the present invention includes:
an image forming portion that forms an image on a recording material; and
a fixing portion that fixes an image formed on a recording material to the recording material, wherein
the fixing portion is the image heating apparatus according to the present invention.
To achieve the above object, in a control method of an image heating apparatus that heats an image formed on a recording material according to the present invention includes:
a heater including a plurality of heating elements which are arranged in a direction orthogonal to a transporting direction of a recording material;
a control portion capable of individually controlling power to be supplied to the plurality of heating elements so as to individually control temperatures of a plurality of heating regions which are heated by the plurality of heating elements; and
an acquisition portion that acquires information on an image formed on a recording material, the control method comprising:
a first step where a region of a recording material, on which an image is formable, is divided into a boundary region and a non-boundary region which are regions divided in a direction orthogonal to the transporting direction so as to correspond to the plurality of heating elements, the boundary region is a region which includes a boundary between one heating element, out of the plurality of heating elements, and an adjacent heating element thereof and overlap with the one heating element and the adjacent heating element by a predetermined range in the direction orthogonal to the transporting direction, and the non-boundary region is a region that overlaps with the one heating element in a range other than the boundary region, and a first temperature based on information corresponding to the boundary region out of the image information, and a second temperature based on information corresponding to the non-boundary region out of the image information are acquired; and
a second step where the control target temperature of a heating region that is heated by the one heating element is set to be a higher temperature of the first temperature and the second temperature.
According to the present invention, a further power saving effect is implemented in a configuration where heating control is performed for a plurality of heating regions independently by a plurality of heating elements disposed in the longer direction, while preventing the generation of a fixing failure and a drop in gloss in a vicinity of the edges of the image.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, a description will be given, with reference to the drawings, of embodiments (examples) of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments.
The image forming apparatus 100 includes a video controller 120 and a control unit (control portion) 113. The video controller 120 receives and processes image information and print instructions which are sent from such an external apparatus as a personal computer, as an acquisition portion that acquires information on an image to be formed on a recording material. The control unit 113 is connected with the video controller 120, and controls each component constituting the image forming apparatus 100, in accordance with the instruction from the video controller 120. When the video controller 120 receives a print instruction from the external apparatus, the following operation to form the image is executed.
The image forming apparatus 100 feeds a recording material P using a feed roller 102 and transports the recording material P toward an intermediate transfer member 103. Each photosensitive drum 104 is rotary-driven counterclockwise by the power of a drive motor (not illustrated) at a predetermined speed and is uniformly charged by a primary charging device 105 during this rotation process. A laser beam, which was modulated corresponding to an image signal, is outputted from a laser beam scanner 106, and selectively scans and exposes the photosensitive drum 104 so as to form an electrostatic latent image. 107 indicates a developing device and visualizes the electrostatic latent image as a toner image (developer image) by attaching powder toner, which is a developer, to the electrostatic latent image. The toner image formed on the photosensitive drum 104 is primarily transferred onto an intermediate transfer member 103 which rotates in contact with the photosensitive drum 104.
The photosensitive drum 104, the primary charging device 105, the laser beam scanner 106 and the developing device 107 are disposed for four colors (cyan (C), magenta (M), yellow (Y) and black (K)) respectively. Four colors of toner images are transferred on the intermediate transfer member 103 sequentially so as to be superimposed by the same procedure. The toner images transferred onto the intermediate transfer member 103 are secondarily transferred onto the recording material P by a secondary transfer portion which is constituted of the intermediate transfer member 103 and a transfer roller 108, using the transfer bias applied to the transfer roller 108. The configuration related to forming an unfixed image on the recording material P corresponds to the image forming portion according to the present invention. The toner image is then fixed by a fixing apparatus (image heating apparatus) 200, which is a fixing portion (image fixing portion) that performs heating and pressing of the recording material P, and the recording material P is discharged from the apparatus as an image forming matter.
The image forming apparatus 100 of Embodiment 1 supports a plurality of recording material sizes and can print images on various sizes of recording materials which are set in a paper feeding cassette 11. The types of recoding materials are, for example, Letter size (about 216 mm×279 mm), Legal size (about 216 mm×356 mm), A4 size (210 mm×297 mm), and Executive size (about 184 mm×267 mm). B5 size (182 mm×257 mm) and A5 size (148 mm×210 mm) are also supported. Irregular sized paper, including DL envelope (110 mm×220 mm) and COM10 envelope (about 105 mm×241 mm) can also be printed. The image forming apparatus 100 of Embodiment 1 is a laser printer which basically feeds the recording material in the vertical direction (transports the recording material so that the longer side of the recording material is parallel with the transporting direction). The largest (widest) size of the widths of the standard size recording materials (widths of recording materials specified in catalog) that this apparatus supports is about a 216 mm width of Letter size and Legal size paper.
The control unit 113 manages the transporting state of the recording material P using a transport sensor 114, a resist sensor 115, a prefixing sensor 116, and a fixed paper discharge sensor 117, disposed on the transport path of the recording material P. The control unit 113 also includes a storage portion that stores a temperature control program and a temperature control table of the fixing apparatus 200. Using the later mentioned method, the control unit 113 controls the temperature of the fixing apparatus 200 based on the image information received from the video controller 120. A control circuit 400, which is a heater driving unit connected to the commercial AC power supply 401, supplies power to the fixing apparatus 200.
The fixing film 202 is a flexible cylindrical multilayer heat resistant film, of which base layer can be a 50 to 100 μm thick heat resistant resin (e.g. polyimide), or a 20 to 50 μm thick metal (e.g. stainless steel). On the surface of the fixing film 202, a release layer is disposed to prevent the attachment of toner and to ensure separation from the recording material P. The release layer is a heat resistant resin which excels in releasability, such as a 10 to 50 μm thick tetra fluoroethylene—perfluoro alkyl vinyl ether copolymer (PFA). In the case of a fixing film that is used for an apparatus to form color images, a heat resistant rubber (e.g. silicon rubber), of which thickness is about 100 to 400 μm and thermal conductivity is about 0.2 to 3.0 W/m·K, may be disposed as an elastic layer between the base layer and the release layer so as to improve image quality. In Embodiment 1, in terms of thermal response, image quality and durability, polyimide, of which thickness is 60 μm, is used for the base layer, silicon rubber, of which thickness is 300 μm and thermal conductivity is 1.6 W/m·K, is used for the elastic layer, and PFA, of which thickness is 30 μm, is used for the release layer.
The pressure roller 208 includes a core metal 209 made of iron, aluminum or the like, and an elastic layer 210 made of silicon rubber or the like. 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 includes a guide function which guides the rotation of the fixing film 202. The metal stay 204 receives pressing force from an energizing member (not illustrated), and energizes the heater holding member 201 toward the pressure roller 208. The pressure roller 208 receives power from the motor 30 and rotates in the arrow R1 direction. By the rotation of the pressure roller 208, the fixing film 202 rotates in the arrow R2 direction accordingly. In the fixing nip portion N, the recording material P is held and transported while receiving heat of the fixing film 202, whereby the unfixed toner image on the recording material P is fixed.
The heater 300 is a heater in which heating resistors, which are heating elements disposed on a ceramic substrate 305, heat up by energization. The heater 300 includes a surface protective layer 308 which contacts the inner surface of the fixing film 202, and a surface protective layer 307 which is disposed on the opposite side (hereafter “back surface side”) of the side where the surface protective layer 308 is disposed on the substrate 305 (hereafter “sliding surface side”). On the back surface side of the heater 300, electrodes to supply power (electrode E4 is indicated here as a representative) are disposed. C4 is an electric contact that contacts with the electrode E4, and supplies power to the electrode via this electric contact. The heater 300 will be described in detail later. A safety element 212 (e.g. a thermo switch, a thermal fuse), which is activated by overheating of the heater 300 and shuts the power to be supplied to the heater 300 OFF, directly contacts the heater 300 on the back surface side of the heater 300, or indirectly contacts the heater 300 via the heater holding member 201.
The heater 300 includes first conductors 301 (301a, 301b) which are disposed on the substrate 305 on the back surface layer side, along the longer direction of the heater 300. The heater 300 also includes second conductors 303 (303-4 is disposed near the transport reference position X) which are disposed on the substrate 305 in the longer direction of the heater 300, at positions which are different from the first conductors 301 in the shorter direction (direction orthogonal to the longer direction) of the heater 300. The first conductors 301 are divided into conductors 301a which are disposed on the upstream side in the transporting direction of the recording material P, and conductors 301b which are disposed on the downstream side thereof. Further, the heater 300 includes a heating resistor 302, each of which is disposed between the first conductor 301 and the second conductor 303, and heats up by power that is supplied via the first conductor 301 and the second conductor 303.
The heating resistors 302 are divided into heating resistors 302a (302a-4 is disposed near the transport reference position X) which are disposed on the upstream side in the transporting direction of the recording material P, and heating resistors 302b (302b-4 is disposed near the transport reference position X) which are disposed on the downstream side thereof. On the back surface layer 2 of the heater 300, an insulating protective layer 307 (glass in Embodiment 1), that covers the heating resistors 302, the first conductors 301 and the second conductors 303 (303-4 is disposed near the transport reference position X), is disposed so as to avoid electrode portions (E4 is disposed near the transport reference position X).
The heating blocks HB1 to HB7 are constituted of heating resistors 302a-1 to 302a-7 and the heating resistors 302b-1 to 302b-7, which are formed to be symmetric with respect to the shorter direction of the heater 300 respectively. The first conductor 301 is constituted of a conductor 301a which is connected with the heating resistors (302a-1 to 302a-7) and the conductor 301b which is connected with the heating resistors (302b-1 to 302b-7). In the same manner, the second conductor 303 is divided into seven (conductors 303-1 to 303-7) in order to support seven heating blocks HB1 to HB7.
In Embodiment 1, the heating block HB4 has a 110 mm width and is used to print DL envelopes and COM 10 envelopes. The heating blocks HB3 to HB5 have a 148 mm width and are used to print A5 size, the heating blocks HB2 to HB6 have a 182 mm width and are used to print B5 size, and the heating blocks HB1 to HB7 have a 220 mm width and are used to print Letter, Legal and A4 size. In this way, the seven heating blocks HB1 to HB7 are divided based on the recording material size supported by the image forming apparatus 100 of Embodiment 1.
Electrodes E1 to E7, E8-1 and E8-2 are used for connecting with electric contacts C1 to C7, C8-1 and C8-2, which are used to supply power from a later mentioned control circuit 400 of the heater 300 respectively. The electrodes E1 to E7 are electrodes used to supply power to the heating blocks HB1 to HB7 via the conductors 303-1 to 303-7 respectively. The electrodes E8-1 and E8-2 are electrodes used to connect to a common electric contact, which is used for supplying power to the seven heating blocks HB1 to HB7 respectively, via the conductor 301a and the conductor 301b.
In Embodiment 1, the electrodes E8-1 and E8-2 are disposed on both edges in the longer direction respectively, but only the electrode E8-1 may be disposed on one edge (that is, the electrode E8-2 is not disposed), or each electrode may be disposed on the upstream and downstream in the recording material transporting direction respectively.
The surface protective layer 307 on 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. Thereby 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. Power to be supplied to at least one heating block of the heating blocks and power to be supplied to the other heating blocks can be controlled independently.
On the sliding surface layer 1 on the side of the sliding surface (surface that contacts the fixing film) of the heater 300, thermistors T1-1 to T1-4 and thermistors T2-5 to T2-7 are disposed to detect the temperature of each heating block HB1 to HB7 of the heater 300. Each of the thermistors T1-1 to T1-4 and the thermistors T2-5 to T2-7 is made of material having PTC characteristics or NTC characteristics (NTC characteristics in the case of Embodiment 1), which is thinly formed on a substrate. Since each of the heating blocks HB1 to HB7 includes a thermistor, the temperatures of all the heating blocks can be detected by detecting the resistance value of each thermistor.
In order to energize the four thermistors T1-1 to T1-4, conductors ET1-1 to ET1-4 for detecting the resistance values of the thermistors, and a common conductor EG1 of the thermistors, are disposed. By a set of these conductors and the thermistors T1-1 to T1-4, a thermistor block TB1 is formed. In the same manner, in order to energize the three thermistors T2-5 to T2-7, conductors ET2-5 to ET2-7 for detecting the resistance values of the thermistors, and a common conductor EG2 of the thermistors, are disposed. By a set of these conductors and the thermistors T2-5 to T2-7, a thermistor block TB2 is formed.
On the sliding surface layer 2 on the side of the sliding surface (surface that contacts the fixing film) of the heater 300, a surface protective layer 308 having sliding characteristics (glass in the case of Embodiment 1) is disposed. The surface protective layer 308 is formed avoiding both edges of the heater 300 in order to dispose electric contacts for the conductors ET1-1 to ET1-4 and ET2-5 to ET2-7 for detecting the resistance values of the thermistors and the common conductors EG1 and EG2 of the thermistors. The surface protective layer 308 is disposed at least on a region sliding with the film 202 on the surface of the heater 300 facing the film 202, avoiding both edges of the heater 300.
As illustrated in
The temperature detection method of the heater 300 will be described. For the temperatures detected by the thermistors T1-1 to T1-4 of the thermistor block TB1, divided voltages using the thermistors T1-1 to T1-4 and the resistors 451 to 454 are detected by the CPU 420 as Th1-1 to Th1-4 signals. In the same manner, for the temperatures detected by the thermistors T2-5 to T2-7 of the thermistor block TB2, divided voltages using the thermistors T2-5 to T2-7 and the resistors 465 to 467 are detected by the CPU 420 as the Th2-5 to Th2-7 signals. In the internal processing of the CPU 420, power to be supplied is calculated based on the difference between the currently deleted control target temperature of each heating block (each heating region heated by each heating block), and the temperature of the thermistor. For example, the power to be supplied is calculated by the PI control. Further, the power to be supplied is converted into a corresponding control level of the phase angle (phase control) and the wave number (wave number control), and the triacs 411 to 417 are controlled under these conditions.
A relay 430 and a relay 440 are used to interrupt power to the heater 300 in the case when the heater 300 overheats due to a failure. The circuit operation of the relay 430 and the relay 440 will be described. When a RLON signal becomes High state, the transistor 433 turns ON, current is supplied from the power supply voltage Vcc to the secondary side coil of the relay 430, and the primary side contact of the relay 430 turns ON. When the RLON signal becomes Low state, the transistor 433 turns OFF, the current that is supplied from the power supply voltage Vcc to the secondary side coil of the relay 430 is interrupted, and the primary side contact of the relay 430 turns OFF. In the same manner, when the RLON signal becomes High state, the transistor 443 is turned ON, current is supplied from the power supply voltage Vcc to the secondary side coil of the relay 440, and the primary side contact of the relay 440 turns ON. When the RLON signal becomes Low state, the transistor 443 is turned OFF, the current that is supplied from the power supply voltage Vcc to the secondary side coil of the relay 440 is interrupted, and the primary side contact of the relay 440 turns OFF.
The operation of the safety circuit using the relay 430 and the relay 440 will be described. When a temperature detected by any one of the thermistors Th1-1 to Th1-4 exceeds a predetermined value which is set for each thermistor, a comparison unit 431 activates a latch unit 432, and the latch unit 432 latches an RLOFF1 signal in the Low state. When the RLOFF1 signal becomes the Low state, even if the CPU 420 sets the RLON signal to the High state, the relay 430 can be kept in the OFF state (safe state) since the transistor 443 is kept in the OFF state. In the non-latch state, the latch unit 432 allows the RLOFF1 signal to be outputted in the open state. In the same manner, when a temperature detected by any one of the thermistors Th2-5 to Th2-7 exceeds a predetermined value which is set for each thermistor, a comparison unit 441 activates a latch unit 442, and the latch unit 442 latches an RLOFF2 signal in the Low state. When the RLOFF2 signal becomes the Low state, even if the CPU 420 sets the RLON signal to the High state, the relay 440 can be kept in the OFF state (safe state) since the transistor 433 is kept in the OFF state. In this case as well, in the non-latch state, the latch unit 442 allows the RLOFF2 signal to be outputted in the open state.
Image data from an external apparatus, such as a host computer, is received by the video controller 120 of the image forming apparatus where image processing is performed. A pixel number of the image forming apparatus of Embodiment 1 is 600 dpi, and the video controller 120 creates a bit map data (image density data for each CMYK color) accordingly. The video controller 120 sends the later mentioned three types of image information acquired by the image processing (image information A, image information B, image information C) to the control unit 113.
The image information A is image information related to the image density in a region of the heating block, excluding the vicinity of the boundary position. The image information B is image information related to the image density in the vicinity of the boundary position of the heating block. The image information C is image information related to the position of the image in the vicinity of the boundary position of the heating block.
Based on the image information A, image information B and image information C, the control unit 113 individually controls power supplied to the seven heating blocks HB1 to HB7 (HBi, i=1 to 7) of the heater 300.
The image information A, the image information B and the image information C will be described in detail.
The video controller 120 analyzes the image density of each color acquired from the CMYK image data received from the host computer using a 1 mm mesh size and calculates the toner amount conversion value for each 1 mm mesh by converting the image density value into a toner amount. As illustrated in
A method of calculating the maximum toner amount conversion value of the image information A will be described. From the image data converted into CMYK image data, d(C), d(M), d(Y) and d(K), which are the image density of each dot of each C, M, Y and K color are acquired, and the total value thereof d (CMYK) is calculated. This calculation is performed for all the dots in each region (A1 to A7), and these values are converted into the toner amount conversion values. In Embodiment 1, the temperature of the heating block HBi is constant (unchanged) within one page. Therefore, the image information Ai is the maximum value of the toner amount conversion values in one page calculated within each region.
Here the image information in the video controller 120 is an 8-bit signal, and the image density d(C), d(M), d(Y) and d(K) for each color of the toner is expressed in a range of the minimum density 00h to the maximum density FFh. The total value thereof, d (CMYK), is a 2 byte 8-bit signal. d(CMYK) is a total value of a plurality of toner colors, and the toner amount conversion value may exceed 100%.
Image Information B
As illustrated in
As illustrated in
Image Information C
The image information C indicates the edge positions of the image in the same boundary region as in the case of the image information B, that is, the distance from the non-boundary region to the image portion included in the boundary region in the longer direction. Out of a plurality of boundary regions that are formed corresponding to a plurality of heating blocks HB, the boundary regions formed on the edges in the longer direction (BL1, BR7) have one adjacent non-boundary region respectively (A1, A7) where there is one image information C. In the other boundary regions (BL2 to BL7, BR1 to BR6), a non-image region adjoins on one side and the other side in the longer direction respectively, hence there are two image information C. In
As illustrated in
In Embodiment 1, the temperature of the heating block HB, is constant within the page. Therefore, the image information CRi and the image information CLi indicate the minimum distance in the page.
The method of the control unit 113, determining the control temperature Ti (i=1 to 7) of the seven heating blocks HBi based on the image information A, image information B and image information C, will be described.
Method of Determining TAi
TAi is a temperature (second temperature) that is required to ensure fixing performance is an area other than the vicinity of the boundary of the heating block HBi. As illustrated in
TAi will be described with reference to
In the image forming apparatus of Embodiment 1, the toner amount on the recording material P is adjusted so that 1.15 mg/cm2 (corresponds to 230% in the case of the toner amount conversion value) is the upper limit. In Embodiment 1, the heat amount required for melting the toner increases as the image density on the recording material P is higher and the toner amount is higher, hence the control temperature must be increased more. As indicated in
Method of Determining TRi, TLi
TRi is a temperature required to ensure the fixing performance in the vicinity of the right side boundary of the heating block HB, (first temperature). As indicated in
TRi will be described with reference to
The temperature TRi can be decreased as the image information CRi, which is a value on the abscissa in
As described above, the control unit 113 determines TRi according to the relationship in
Flow of Determining Control Temperature
If the heating block for which the control temperature is determined is HB1 (Yes in S603, Yes in S607), TL1 is determined (acquired) from the image information BL1 and the image information CL1 in S608 using the relationship in
Power consumption was compared between Embodiment 1 and Comparative Embodiment 1. The power consumption was measured under the following conditions, using the image forming apparatus 100. The process speed of the image forming apparatus 100 according to Embodiment 1 is 210 mm/s, and in the case of Letter size, 40 pages per minute (ppm) of throughput can be implemented in continuous printing. The recording material used here is multipurpose paper (basis weight: 75 g/m2, Letter size) made by HP. The image is a 230% image as illustrated in
Comparative Embodiment 1 is a case where the present invention is not used, and HB3 and HB5 are recognized as image portions. Therefore, the control temperature is set to a same temperature as HB4 (210 deg.). In Embodiment 1, on the other hand, the temperature of the HB3 is set such that the control temperature be 180 deg. because of the image information BR3=230%, and CR3=3 mm and the above relationship in
As a result of measuring power under the above conditions, the average power consumed by the fixing apparatus 200 of Embodiment 1 was 560 W. In the case of Comparative Embodiment 1, on the other hand, the average power was 587 W. Compared with Comparative Embodiment 1, Embodiment 1 can decrease the control temperatures HB3 and HB5, therefore a 27 W of power saving effect is implemented.
As described above, in the image forming apparatus that adjusts the heating conditions of a plurality of heating blocks disposed in the longer direction in accordance with the image information, the power saving effect can be improved if Embodiment 1 is applied.
In Embodiment 1, the seven heating blocks are divided based on the recording material sizes supported by the imaging forming apparatus 100 but may be divided by a different method. A number of heating blocks is seven in the longer direction according to the above description, but a number of heating blocks may be any number that is at least two in the longer direction to apply the setting according to Embodiment 1.
In Embodiment 1, the temperature of the heating block HBi is constant within one page, but the control temperature may be changed if necessary, by updating the image information within one page if necessary. The image information is acquired in units of a 1 mm mesh size, but the mesh size may be changed if necessary.
In Embodiment 1, the recording material P is set so that the center portion of the recording material P passes through the transport reference position X during transporting, but as illustrated in
The configurations of an image forming apparatus, an image heating apparatus, a heater, and a heater control circuit are the same as Embodiment 1, hence description thereof will be omitted. In Embodiment 2, the control temperature Ti of the heating block HBi is determined by a method different from Embodiment 1. In Embodiment 1, the control temperature Ti of each heating block HBi is determined using the image information A, the image information B, and the image information C. By this method, however, when more detailed information is acquired (e.g. a 1 mm mesh of Embodiment 1 is further divided), processing by the video controller 120 may not keep up since the information volume of the image is too large.
In many cases, an image that is normally outputted is an image that is drawn within a predetermined range of the recording material P, as illustrated in
Further, in many cases, an image that is normally outputted is not an image where such image attributes as text and graphics do not coexist within one page. In this case, the maximum toner amount conversion value in each heating block is not so different from each other, hence the control temperature difference among the image heating portions is not so large. Therefore, a better power saving effect may be expected in some cases by decreasing the control temperature of the non-image heating portions, rather than a power saving effect implemented by determining the control temperatures of the image heating portions using the image information A, the image information B, and the image information C.
Therefore in Embodiment 2, in order to determine the control temperatures of non-image heating portions more accurately, the resolution of the image distance of the image information C related to the control temperatures is made even finer. The resolution is 1 mm in Embodiment 1 but is 0.1 mm in Embodiment 2. Accordingly, the information amount to determine the control temperatures of the image heating portions is decreased as follows. In Embodiment 1, the image information A is a 2 byte 8-bit signal, but in Embodiment 2, the image information A is a 1 byte 3-bit signal, and the maximum toner amount conversion value is expressed in 16 levels, as indicated in Table 2. The image information B and the image information C to determine the control temperatures of the image heating portions do not exist, and the control temperatures of the image heating portions are determined by the image information A alone.
As illustrated in
In Case 1 in
In Case 2 in
Power consumption was compared among Embodiment 2, Comparative Embodiment 2, and Embodiment 1. The power consumption was measured under the same conditions as Embodiment 1, using the image forming apparatus 100. The image of Embodiment 2 is a 230% image and a 185% image, as illustrated in
Comparative Embodiment 2 is a case where the present invention is not used, and HB2 and HB6 are recognized as image portions. Therefore, the control temperature of HB2 is set to a same temperature as HB3 (210 deg.), and the control temperature of HB6 is set to a same temperature as HB5 (199 deg.).
Just like the relationship in
Just like the relationship in
As a result of measuring power under the above conditions, the average power consumed by the fixing apparatus 200 of Embodiment 2 was 609 W. On the other hand, the average power was 632 W in the case of Comparative Embodiment 2 and was 616 W in the case of Embodiment 1. Embodiment 2 can decrease the control temperatures of HB2 and HB6 than Comparative Embodiment 2 and Embodiment 1, although the temperature of HB5 is slightly higher, and therefore a power saving effect is implemented.
As described above, in the image forming apparatus that adjusts the heating conditions of a plurality of heating blocks disposed in the longer direction in accordance with the image information, a power saving effect can be improved if Embodiment 2 is applied.
Configurations of the above embodiments may be combined as much as possible.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2018-218910, filed on Nov. 22, 2018, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-218910 | Nov 2018 | JP | national |
