JP2019020482A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

A continuous fixing process is smoothly performed regardless of a sheet size. A fixing device of a printer includes a heating member that heats a toner image formed on a sheet using a heat source. The heat source 23 includes a plurality of heating bodies 31, 32, and 33 arranged along the width direction orthogonal to the sheet conveyance direction, and the larger the width of the sheet on which the fixing process is performed, the more heating bodies 31, 32. And 33 are controlled to heat. Then, the fixing device 13 is larger in width than the small size paper while performing the fixing process by heating the heating body 31 at a position corresponding to the small size paper in the width direction for the small size paper. When an instruction for fixing the normal size paper is input, the heating bodies 32 and 33 at positions corresponding to the normal size paper outside the heating body 31 in the width direction before the end of the fixing process for the small size paper. Start heating. [Selection] Figure 3

Description

  The present invention relates to a fixing device that fixes a toner image on a sheet, and an image forming apparatus including the fixing device.

  The image forming apparatus includes a fixing device that heats and fixes a toner image formed on a sheet. The fixing device includes a heating member that heats the toner image and a pressure member that pressurizes the toner image against the paper. The fixing device is required to perform appropriate heating for each of various sizes of paper.

  For example, in Patent Document 1, an image heating apparatus (fixing apparatus) includes a heating rotator, a pressure rotator, a heating body, and a control unit. The pressure rotator forms a nip portion that heats the recording material that carries the image with the heating rotator while sandwiching and conveying the recording material. The heating body is a heating body that heats the heating rotator, and is arranged side by side along the longitudinal direction of the heating rotator, and has a plurality of heating elements that generate heat when powered individually. When the control unit continuously introduces and heats a recording material having a width smaller than the maximum width size of the recording material that can be introduced into the apparatus, the control unit Controls the amount of power supplied to the heating element corresponding to the non-passing portion.

Japanese Patent Laid-Open No. 2015-028531

  In a fixing device having a plurality of heating elements along the width direction of the paper, when fixing a relatively small size paper, in order to suppress excessive temperature rise at the end in the width direction and realize energy saving. Then, the heating body in the necessary area corresponding to the paper width is heated. For this reason, since the heating body in the region outside the paper width is not energized, the temperature of the heating member is lower at the end portion than at the central portion in the width direction after the fixing processing of the small size paper. In such a state, when the fixing process of a sheet having a larger width is continuously performed, the end in the width direction of the heating member needs to be heated to the fixing temperature, and thus downtime occurs due to the heating. This causes a problem that the continuous fixing process cannot be performed smoothly.

  In view of the above circumstances, an object of the present invention is to smoothly perform continuous fixing processing regardless of the paper size.

  The fixing device of the present invention includes a heating member that heats a toner image formed on a sheet using a heat source, and the heat source is disposed in a plurality of heating directions arranged in a width direction orthogonal to the conveyance direction of the sheet. The plurality of heating bodies are controlled to heat more heating bodies as the width of the sheet on which the fixing process is performed is larger. With respect to the first sheet having a predetermined width, When an instruction for fixing processing of a second sheet having a width larger than that of the first sheet is input while the fixing process is performed by heating the first heating body at a position corresponding to the first sheet, the first sheet Before the end of the fixing process for one sheet, heating of the second heating body at a position corresponding to the second sheet outside the first heating body in the width direction is started.

  The heating member may further include a rotatable fixing belt, and the plurality of heating bodies may be disposed in contact with an inner peripheral surface of the fixing belt.

  The fixing device further includes a pressing member that is disposed in contact with the fixing belt of the heating member and pressurizes the paper that passes between the heating member, and the plurality of heating bodies includes the fixing member. It is preferable that the belt is disposed inside the belt so as to face the pressure member with the fixing belt interposed therebetween.

  The plurality of heating bodies may be made of a conductive paint.

  The image forming apparatus of the present invention includes the above-described fixing device.

  According to the present invention, it is possible to smoothly perform continuous fixing processing regardless of the paper size.

1 is a cross-sectional view illustrating a printer according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device of a printer according to an embodiment of the present invention. It is a bottom view showing a heat source in the fixing device of the printer according to the embodiment of the present invention. 1 is a block diagram illustrating an electrical configuration of a fixing device of a printer according to an embodiment of the present invention. 6 is a graph illustrating an example of heating control in a fixing device of a printer according to an embodiment of the present invention. 6 is a flowchart illustrating an operation of a fixing process when a print job for a small-size sheet is input in the fixing device of the printer according to the embodiment of the present invention.

  First, the overall configuration of a printer 1 (image forming apparatus) according to an embodiment of the present invention will be described with reference to FIG. Hereinafter, for convenience of explanation, the front side of the sheet in FIG. Arrows L, R, U, and Lo appropriately attached to the drawings indicate the left side, right side, upper side, and lower side of the printer 1, respectively.

  The printer 1 includes a substantially box-shaped printer main body 2. A paper feed cassette 3 for storing paper (recording medium) is provided at a lower portion of the printer main body 2. A paper discharge tray 4 is provided at the upper portion of the printer main body 2. Provided. In FIG. 1, one paper feed cassette 3 is illustrated, but the printer 1 includes a plurality of paper feed cassettes 3 so as to accommodate paper of a plurality of types (for example, A4 size, A5 size, etc.). It's okay.

  An exposure unit 5 composed of a laser scanning unit (LSU) is disposed below the discharge tray 4 in the upper part of the printer main body 2, and an image forming unit 6 is provided below the exposure unit 5. . The image forming unit 6 is rotatably provided with a photosensitive drum 7 as an image carrier. Around the photosensitive drum 7, a charger, a developing device connected to a toner container, a transfer roller, A cleaning device is arranged along the rotation direction of the photosensitive drum 7.

  In addition, a paper conveyance path 10 is provided inside the printer main body 2. A paper feeding unit 11 is provided in the vicinity of the paper feeding cassette 3 at the upstream end of the conveyance path 10, and a transfer unit 12 including a photosensitive drum 7 and a transfer roller is provided in the middle part of the conveyance path 10. A fixing device 13 is provided in the downstream portion of the transport path 10, and a paper discharge unit 14 is provided in the vicinity of the paper discharge tray 4 at the downstream end of the transport path 10. In addition, a control device 15 that controls the fixing device 13 is provided inside the printer body 2.

  Next, an image forming operation of the printer 1 having such a configuration will be described. The printer 1 starts an image forming operation when image data is input from an external computer or the like and an instruction to start printing is given. For example, the printer 1 inputs and accumulates image data print jobs, sequentially processes the accumulated print jobs by an image forming operation, and deletes the processed print jobs. In the print job, the size of paper to be printed is also specified. In the image forming operation, first, the surface of the photosensitive drum 7 is charged by the charger of the image forming unit 6, and then exposure corresponding to the image data is performed on the photosensitive drum 7 by the laser light from the exposure device 5. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 7. Next, the developing device of the image forming unit 6 develops the electrostatic latent image into a toner image using toner.

  On the other hand, among the sheets stored in the sheet feeding cassette 3, the sheet designated by the print job is taken out by the sheet feeding unit 11 and conveyed on the conveying path 10. The sheet on the conveyance path 10 is conveyed to the transfer unit 12 at a predetermined timing, and the toner image on the photosensitive drum 7 is transferred to the sheet by the transfer unit 12. The sheet on which the toner image has been transferred is conveyed to the fixing device 13 and the toner image is fixed on the sheet by the fixing device 13. The paper on which the toner image is fixed is discharged from the paper discharge unit 14 to the paper discharge tray 4.

  Next, the configuration of the fixing device 13 will be described with reference to FIGS. As shown in FIG. 2, the fixing device 13 includes a heating member 20 and a pressure member 21. The fixing device 13 includes a drive source 26 (see FIG. 4), a central temperature sensor 27, an end temperature sensor 28, and a paper sensor 29. The heating member 20 includes an endless fixing belt 22 and a heat source 23 disposed in a hollow portion of the fixing belt 22. The heating member 20 and the pressure member 21 are arranged to face and contact each other with the conveyance path 10 interposed therebetween, and a fixing nip N is formed between the heating member 20 and the pressure member 21.

  The fixing belt 22 of the heating member 20 is made of a flexible material and is formed in a substantially cylindrical shape that is long in the paper width direction (front-rear direction) orthogonal to (crossing) the paper transport direction (left-right direction). The fixing belt 22 is disposed at an upper portion in a frame (not shown) of the fixing device 13. The fixing belt 22 is rotatably attached to the frame with the front-rear direction as the rotation axis direction, and rotates in accordance with the rotation of the pressure member 21. The fixing belt 22 may be provided with a shape regulating member (not shown) that regulates the shape of the fixing belt 22 from the inside.

  As shown in FIG. 3, the heat source 23 of the heating member 20 has a long shape in the paper width direction (front-rear direction). The heat source 23 includes a plate-like substrate 30 that is long in the width direction and a plurality of heating bodies 31, 32, and 33.

  The plurality of heating bodies 31, 32, and 33 are arranged along the width direction on one surface (for example, the lower surface) of the substrate 30. The heat source 23 is arranged in a state in which one surface of the substrate 30 on which the plurality of heating bodies 31, 32, and 33 are provided faces the pressure member 21 and is in contact with the inner peripheral surface of the fixing belt 22. The heat source 23 is supported by a support member 24 that is long in the width direction, and is arranged so as to press the fixing belt 22 from the inside toward the pressure member 21 side. The heat source 23 heats the heating members 31, 32, and 33 to heat the pressure member 21 side (for example, the lower side) of the fixing belt 22 in the front-rear direction. Note that the location of the fixing belt 22 heated by the heat source 23 varies as the fixing belt 22 rotates.

  The plurality of heating bodies 31, 32, and 33 are made of, for example, a conductive paint having a predetermined resistance value, and are applied to the substrate 30. The plurality of heating bodies 31, 32, and 33 are arranged over a normal size region A that covers the width of a normal size sheet (for example, A4 size) that passes through the heating member 20. Specifically, the heating body 31 (first heating body) in the center in the width direction extends over a small size region B corresponding to the width of a relatively small size (for example, A5 size) paper that passes through the heating member 20. Be placed. In addition, the heating bodies 32 and 33 (second heating bodies) at both ends in the width direction are arranged over the normal end region C on both ends of the small size region B in the width direction. In other words, the small-size paper is the first paper having a predetermined width, and the normal-size paper is the second paper having a larger width than the first paper.

  A first terminal 34, a second terminal 35, and a third terminal 36 connected to a power source (not shown) are provided at the end of the substrate 30. One end of the heating body 31 at the center in the width direction is connected to the first terminal 34, and one end of the heating bodies 32 and 33 at both ends in the width direction is connected to the second terminal 35. The other ends of the plurality of heating bodies 31, 32 and 33 are connected to the third terminal 36. The plurality of heating bodies 31, 32, and 33 are supplied with power (not shown) between the first terminal 34, the second terminal 35, and the third terminal 36 while an ON control signal is input from the control device 15. ). On the other hand, the plurality of heating elements 31, 32, and 33 are cut off from the power supply from a power source (not shown) while an OFF control signal is input from the control device 15.

  Specifically, by supplying power between the first terminal 34 and the third terminal 36, the heating body 31 in the center in the width direction is energized and heated, and the small size region B of the fixing belt 22 is heated. Further, by supplying electric power between the second terminal 35 and the third terminal 36, the heating bodies 32 and 33 at both ends in the width direction are energized and heated, and the normal end region C of the fixing belt 22 is heated. Accordingly, the normal size region A of the fixing belt 22 is heated by simultaneously heating the small size region B and the normal end region C of the fixing belt 22. In other words, the heat source 23 is provided with a plurality of heating bodies 31, 32, and 33 so that the heating region is divided into a plurality of parts.

  The pressure member 21 is formed in a substantially cylindrical shape that is long in the width direction (front-rear direction) of the paper. The pressure member 21 is disposed in the lower part of the frame (not shown) of the fixing device 13, for example, below the fixing belt 22, so that the outer peripheral surfaces of the fixing belt 22 face each other. The pressure member 21 is rotatably attached to the frame with the front-rear direction as the rotation axis direction, and rotates by a rotational driving force transmitted from a drive source 26 (see FIG. 4) such as a motor. The pressure member 21 includes, for example, a cylindrical metal core material and an elastic layer such as silicon rubber provided around the core material, and the elastic layer may be covered with a release layer.

  Next, the electrical configuration of the control device 15 that controls the fixing device 13 will be described with reference to FIG. The control device 15 is composed of a CPU or the like, and is connected to a storage device 16 such as a ROM or a RAM. In addition, as the control device 15 and the storage device 16, a main control device and a main storage device that collectively control each unit of the printer 1 may be applied.

  The control device 15 controls each unit connected to the control device 15 based on a control program and control data stored in the storage device 16. For example, the control device 15 is connected to the heat source 23, the drive source 26, the central temperature sensor 27, the end temperature sensor 28, and the paper sensor 29. When the printer 1 processes a print job, the control device 15 controls the fixing device 13 so as to perform a fixing process corresponding to the print job.

  For example, a fixing process when a normal size paper print job is input will be described. In this case, the control device 15 controls the heat source 23 so as to heat the plurality of heating bodies 31, 32 and 33 corresponding to the normal size paper. At this time, the control device 15 monitors the temperatures of the small size region B and the normal end region C of the fixing belt 22 by the central temperature sensor 27 and the end temperature sensor 28, respectively, that is, the temperature of the normal size region A. Is monitoring. Then, the control device 15 continues to heat the plurality of heating bodies 31, 32, and 33 until the temperature of the normal size region A of the fixing belt 22 reaches a predetermined fixing temperature (see FIG. 5). When the temperature reaches the fixing temperature, the temperature of the fixing belt 22 is maintained at the fixing temperature by switching between heating and stopping of the plurality of heating bodies 31, 32 and 33.

  A fixing process when a print job for one or more small-size sheets (hereinafter referred to as a first job) is input will be described with reference to the flowchart of FIG. When the first job is input (step S1), the control device 15 controls the heat source 23 so as to heat the heating body 31 at the center in the width direction corresponding to the small size paper (step S2). At this time, the control device 15 monitors the temperature of the small size region B of the fixing belt 22 by the central temperature sensor 27, and the temperature T1 of the small size region B of the fixing belt 22 is measured in the same manner as the normal size paper. The heat source 23 is controlled so as to be raised to the fixing temperature and maintained (see FIG. 5). When the temperature T1 of the small size region B of the fixing belt 22 reaches the fixing temperature, the control device 15 starts the fixing process of the first job. At this time, the heating bodies 32 and 33 at both ends in the width direction are not heated. However, the temperature T2 of the normal end region C of the fixing belt 22 is affected by the heating by the heating body 31 at the center in the width direction, and the normal temperature. Can be expensive.

  Further, when the first job is input, the control device 15 predictively calculates the end time FT of the first job in the fixing device 13. This end time FT is the time for the last sheet of the first job to finish passing through the fixing nip N between the heating member 20 and the pressure member 21. Hereinafter, calculation of the end time FT will be described.

  In the fixing device 13, the rotation speed of the pressure member 21 (heating member 20) at the time of fixing the small size paper is set in advance to a predetermined speed and stored in the storage device 16. In the fixing device 13, the length of one small size sheet in the conveyance direction is also defined or set in advance and stored in the storage device 16. Therefore, the unit passing time during which one small-size sheet passes through the fixing nip N is obtained by dividing the length in the conveyance direction of one small-size sheet by the rotation speed of the pressure member 21. It is calculated in advance and stored in the storage device 16. Then, when the first job is input, the control device 15 multiplies the number of small-size sheets of the first job by the unit passage time of one small-size sheet to obtain one sheet of the first job. A total passing time PT during which all the above small size sheets pass through the fixing nip N is calculated (step S3). In calculating the total transit time PT, when one or more small-size sheets of the first job are sequentially fixed at a predetermined interval (inter-sheet time), the number of sheets of the first job is calculated. The time obtained by multiplying the number obtained by subtracting 1 by the paper interval time may be added.

  In the fixing device 13, the paper sensor 29 detects the paper passing through the fixing nip N. Based on the detection result of the paper sensor 29, the control device 15 performs the first job when the first sheet of one or more small-sized sheets of the first job starts to pass through the fixing nip N. The start time ST1 is measured and stored in the storage device 16 (step S4). The control device 15 calculates the end time FT of the first job in the fixing device 13 by adding the total passage time PT to the first job start time ST1 (step S5).

  By the way, a normal size paper print job (hereinafter referred to as a second job) may be input in succession to the small size paper print job (step S6: YES). At this time, as shown in FIG. 5, the control device 15 sets the temperature T2 of the normal end region C of the fixing belt 22 to the fixing temperature at the end of the fixing process of the small-size paper of the first job. The heat source 23 is controlled so that heating of the heating bodies 32 and 33 at both ends in the width direction is started before the start of two jobs and during or before the processing of the first job.

  For example, in the fixing device 13, the arrival time AT from the start of heating the heating bodies 32 and 33 at both ends in the width direction until the temperature T2 of the normal end region C of the fixing belt 22 reaches the fixing temperature is measured in advance. Alternatively, it is calculated and stored in the storage device 16. Then, when the second job is input during the processing of the first job, the control device 15 subtracts this arrival time AT from the end time FT of the first job, so that the fixing process of the first job is performed. A heating start time HT for starting heating of the heating bodies 32 and 33 at both ends in the width direction for the second job is calculated (step S7).

  When the heating start time HT is reached (step S8: YES), the control device 15 controls the heat source 23 to start heating the heating bodies 32 and 33 at both ends in the width direction (step S9). At this time, the control device 15 monitors the temperature T2 of the normal end region C of the fixing belt 22 by the end temperature sensor 28, and increases the temperature T2 of the normal end region C of the fixing belt 22 to the fixing temperature. .

  Thereafter, when the end time FT of the first job is reached (step S10: YES), the control device 15 ends the fixing process of the first job (step S11). At this time, an arrival time AT from the heating start time HT to the fixing temperature of the heating bodies 32 and 33 at both ends in the width direction has elapsed, and the temperature T2 in the normal end region C of the fixing belt 22 becomes the fixing temperature. Therefore, the control device 15 can start the fixing process of the second job.

  Thereafter, when the fixing process of the second job is completed (step S12: YES), the control device 15 causes the heat source to stop heating the heating body 31 at the center in the width direction and the heating bodies 32 and 33 at both ends in the width direction. 23 is controlled.

  When a print job for the normal size paper (second job) is not input continuously after the print job for the small size paper (first job) (step S6: NO), the heating elements 32 at both ends in the width direction are used. And the heating start time HT of 33 is not necessary. When the fixing process of the first job is completed (step S13: YES), the control device 15 controls the heat source 23 so as to stop the heating of the heating body 31 at the center in the width direction.

  According to the present embodiment, as described above, the fixing device 13 of the printer 1 (image forming apparatus) includes the heating member 20 that heats the toner image formed on the paper using the heat source 23. The heat source 23 includes a plurality of heating bodies 31, 32, and 33 arranged along the width direction orthogonal to the sheet conveyance direction, and the larger the width of the sheet on which the fixing process is performed, the more heating bodies 31, 32. And 33 are controlled to heat. Then, the fixing device 13 heats the heating body 31 (first heating body) at a position corresponding to the small-size paper in the width direction for the small-size paper (first paper having a predetermined width) and performs the fixing process. If an instruction for fixing a normal size paper (second paper) that is wider than a small size paper is input during the process, heating is performed in the width direction before the end of the fixing processing for the small size paper. Heating of the heating bodies 32 and 33 (second heating body) at positions corresponding to normal size paper outside the body 31 is started.

  As a result, in the case where the fixing process of different size sheets is continuously performed, the heat source 23 can be sufficiently heated in accordance with the sheet of the subsequent fixing process before the subsequent fixing process is started. Therefore, the heating time of the heat source 23 for the subsequent fixing process can be shortened, and the downtime required for the preparation for the subsequent fixing process can be suppressed. Therefore, it is possible to smoothly perform continuous fixing processing regardless of the paper size.

  In the control device 15, the heating member 20 further includes a rotatable fixing belt 22, and the plurality of heating bodies 31, 32, and 33 are disposed in contact with the inner peripheral surface of the fixing belt 22. Accordingly, in the configuration in which the fixing belt 22 is heated from the inside, continuous fixing processing can be smoothly performed regardless of the paper size.

Further, the control device 15 further includes a pressurizing member 21 that is disposed in contact with the fixing belt 22 of the heating member 20 and pressurizes the paper passing between the heating member 20.
The plurality of heating bodies 31, 32, and 33 are disposed inside the fixing belt 22 and opposed to the pressure member 21 with the fixing belt 22 interposed therebetween. Thus, the plurality of heating bodies 31, 32, and 33 are arranged at optimal positions for heating in contact with the inner peripheral surface of the fixing belt 22. Since the pressure member 21 side of the fixing belt 22 is heated, the heating time can be shortened as compared with the configuration in which the other portions of the fixing belt 22 are heated.

  Moreover, in the control apparatus 15, the several heating bodies 31, 32, and 33 are comprised with an electroconductive coating material. Thereby, the structure of the several heating bodies 31, 32, and 33 which divided | segmented the heating area | region of the heat source 23 is easily realizable.

  In the above-described embodiment, the example in which the heating start time HT of the heating bodies 32 and 33 at both ends in the width direction is calculated on the basis of the end time FT of the first job has been described. It is not limited. For example, in another embodiment, the heating start time HT may be calculated based on the start time of the second job. In this case, the calculation of the start time of the second job may take into account the inter-paper time between the first job and the second job.

  In the above-described embodiment, the example in which the end time FT of the first job is calculated when the first job is input has been described. However, the calculation of the end time FT is not limited to this example. For example, in another embodiment, the end time FT may be calculated when the second job is input.

  Furthermore, in the above-described embodiment, an example in which the heat source 23 is configured by the three heating bodies 31, 32, and 33 is described in order to support two sizes of paper. However, the configuration of the heat source 23 is limited to this example. Not. For example, in other embodiments, the heat source 23 may be composed of two heating elements to accommodate two sizes of paper, or 4 to accommodate three or more sizes of paper. You may be comprised from two or more heating bodies.

  In the present embodiment, the case where the configuration of the present invention is applied to the monochrome printer 1 has been described. However, in another different embodiment, the present invention is applied to other image forming apparatuses such as a color printer, a copier, a facsimile machine, and a multifunction machine. It is also possible to apply this configuration.

1 Printer (image forming device)
Reference Signs List 6 Image forming unit 10 Conveyance path 13 Fixing device 15 Control device 20 Heating member 21 Pressure member 22 Fixing belt 23 Heat source 27 Central temperature sensor 28 Edge temperature sensor 29 Paper sensor 30 Substrate 31, 32, 33

Claims (5)

A heating member for heating the toner image formed on the paper using a heat source;
The heat source includes a plurality of heating elements arranged along a width direction orthogonal to the sheet conveyance direction, and heats more heating elements as the width of the sheet on which fixing processing is performed is larger. Controlled,
For a first sheet having a predetermined width, a second sheet having a width larger than that of the first sheet is being fixed while heating the first heating element at a position corresponding to the first sheet in the width direction. When an instruction for fixing the sheet is input, the second heating body at a position corresponding to the second sheet outside the first heating body in the width direction before the end of the fixing process of the first sheet. The fixing device is characterized by starting heating of the fixing device. The heating member further comprises a rotatable fixing belt,
The fixing device according to claim 1, wherein the plurality of heating bodies are disposed in contact with an inner peripheral surface of the fixing belt. A pressure member that is disposed in contact with the fixing belt of the heating member and pressurizes the paper that passes between the heating member;
The fixing device according to claim 2, wherein the plurality of heating bodies are arranged inside the fixing belt and opposed to the pressure member with the fixing belt interposed therebetween.   The fixing device according to claim 1, wherein the plurality of heating bodies are made of a conductive paint.   An image forming apparatus comprising the fixing device according to claim 1.

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