JP2015141241A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact image forming apparatus.SOLUTION: An image forming apparatus for forming an image on a recording medium measures a thickness of the recording medium, performs first conveyance which conveys the recording medium in order to form images on both sides of the recording medium, performs discharge processing for discharging the recording medium, performs second conveyance which conveys the recording medium to first conveyance means, and performs switching processing which causes the second conveyance to discharge or convey the recording medium. When a thick part having a predetermined thickness or more is measured, the switching processing is performed to cause the second conveyance to convey the recording material, instead of discharging it, on the basis of a location of the thick part.

Description

  The present invention relates to an image forming apparatus and an image forming method.

  2. Description of the Related Art Conventionally, when an image forming apparatus detects that a plurality of recording media are conveyed in an overlapped state, a method is known in which the upstream conveying unit is stopped to eliminate the overlapping of the recording media (for example, Patent Documents). 1).

  However, in the method of Patent Document 1, since a certain distance is provided between the sensor for detecting the overlap of the recording media and the upstream conveying unit and the downstream conveying unit for the recording medium, the image forming apparatus may be large. there were.

  An object of one aspect of the present invention is to provide a small image forming apparatus.

  An image forming apparatus for forming an image on a recording medium according to an aspect, wherein the first measuring unit measures the thickness of the recording medium, and transports the recording medium to form an image on both sides of the recording medium. The discharge means performs a discharge process for discharging the recording medium, a second transfer means for transferring the recording medium to the first transfer means, and a process performed by the second transfer means. A switching means for performing a switching process for switching between the processing and the transport process, and when the thickness portion that is equal to or greater than a predetermined thickness is measured by the measuring means, the switching means is a location of the thickness portion. On the basis of the above, the switching process for switching the process performed by the second transport unit from the discharge process to the transport process is performed.

  The image forming apparatus can be reduced in size.

1 is a diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a functional block diagram illustrating an example of a functional configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure explaining an example of the measurement of the thickness by the measurement part which concerns on one Embodiment of this invention. It is a figure explaining an example of the measurement result by thickness measurement concerning one embodiment of the present invention. It is a flowchart explaining an example of the whole process which concerns on one Embodiment of this invention. It is a figure explaining an example of the switching process which concerns on one Embodiment of this invention, a discharge process, and a conveyance process. It is a timing chart explaining an example of the timing of the whole processing concerning one embodiment of the present invention. FIG. 6 is a diagram illustrating an example of fixing processing and fixing control according to an embodiment of the present invention. It is a flowchart explaining an example of the whole process of 2nd Embodiment which concerns on one Embodiment of this invention. It is a flowchart explaining an example of the whole process of 3rd Embodiment which concerns on one Embodiment of this invention. It is a flowchart explaining an example of the whole process of 4th Embodiment which concerns on one Embodiment of this invention. It is a flowchart explaining an example of the whole process of 5th Embodiment which concerns on one Embodiment of this invention. It is a flowchart explaining an example of the whole process of 6th Embodiment which concerns on one Embodiment of this invention. It is a figure explaining an example of the whole structure of the image forming apparatus of 7th Embodiment which concerns on one Embodiment of this invention. It is a flowchart explaining an example of the whole process of 7th Embodiment which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described below.

<First Embodiment>
<Overall configuration of image forming apparatus>
FIG. 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus is, for example, the image forming apparatus 1. The image forming apparatus 1 is an electrophotographic image forming apparatus having a secondary transfer mechanism called a tandem method in color image formation, for example. Hereinafter, the case of FIG. 1 will be described as an example.

  The image forming apparatus 1 includes developing units 1H1A, 1H1B, 1H1C, 1H1D for each color, toner containers 1H2A, 1H2B, 1H2C, 1H2D for each color, and a transfer belt 1H3. The image forming apparatus 1 includes a transfer belt driving roller 1H4 and a transfer belt tension roller 1H5.

  Each color developing unit 1H1A, 1H1B, 1H1C, 1H1D, and each color toner container 1H2A, 1H2B, 1H2C, 1H2D are arranged along the transfer belt 1H3, for example.

  The developing units 1H1A, 1H1B, 1H1C, 1H1D, and the toner containers 1H2A, 1H2B, 1H2C, 1H2D correspond to the respective colors. The colors are, for example, yellow (Y), cyan (C), magenta (M), black (K), and the like (hereinafter, the color may be appropriately represented by symbols shown in parentheses).

  The transfer belt 1H3 is held by a transfer belt drive roller 1H4 and a transfer belt tension roller 1H5, and is driven by the rotation of the transfer belt drive roller 1H4.

  The development unit 1H1A includes a photoreceptor 1H6A, a charger 1H7A, an exposure unit 1H8, a development unit 1H9A, and a cleaner blade 1H10A.

  The charger 1H7A, the exposure device 1H8, the developing device 1H9A, and the cleaner blade 1H10A are arranged around the photoreceptor 1H6A.

  Since the developing units 1H1B, 1H1C, and 1H1D have the same configuration as the developing unit 1H1A, description thereof is omitted.

  The exposure device 1H8 emits laser beams 1H11A, 1H11B, 1H11C, and 1H11D corresponding to the respective colors.

  The image forming apparatus 1 includes a paper feed tray 1H13, a paper feed roller 1H14, a registration roller 1H15, a paper discharge roller 1H16, a double-sided roller 1H17, and a secondary transfer roller 1H18. The image forming apparatus 1 includes a fixing device 1H19, a paper discharge sensor 1H20, a waste toner box 1H21, and primary transfer rollers 1H22A, 1H22B, 1H22C, and 1H22D for each color. The image forming apparatus 1 includes a registration sensor 1H23, a recording medium amount sensor 1H24, a duplex sensor 1H25, a paper discharge tray 1H26, a thickness sensor 1H27, and a paper discharge roller solenoid 1H28.

  The paper feed tray 1H13 accommodates the recording medium 1H12. The recording medium 1H12 is, for example, paper, high-quality paper, a plastic sheet, or a metal sheet.

  In the present application, the recording medium may be simply referred to as a “recording medium” as a bundle of recording media in which two or more recording media overlap each other.

  Also, “multiple feeding” (hereinafter referred to as “multiple feeding”) means that two or more recording media are overlapped or transported in a state where two or more recording media are shifted and overlapped at each end. There is).

  The paper feed roller 1H14 is a mechanism for transporting the recording medium 1H12 from the paper feed tray 1H13. The paper feed roller 1H14 includes, for example, a roller mechanism and a pad so-called friction pad (not shown) installed with respect to the roller mechanism.

  The registration roller 1H15 is a mechanism for conveying the recording medium 1H12 conveyed by the paper supply roller 1H14 to the secondary transfer roller 1H18.

  The paper discharge roller 1H16 is a mechanism for discharging the recording medium 1H12 from the image forming apparatus 1. The recording medium 1H12 discharged by the paper discharge roller 1H16 is conveyed to the paper discharge tray 1H26.

  When forming an image on both sides of the recording medium 1H12, the double-sided roller 1H17 conveys the recording medium 1H12 so that the image is formed on one side of the recording medium 1H12 and then formed on the other side of the recording medium 1H12. It is a mechanism to do.

  The secondary transfer roller 1H18 is a mechanism for performing so-called secondary transfer, in which an image formed on the transfer belt 1H3 is transferred to the recording medium 1H12.

  The fixing device 1H19 is a device for fixing the toner transferred to the recording medium 1H12 by the secondary transfer.

  The paper discharge sensor 1H20 is a sensor that detects the recording medium 1H12 discharged by the paper discharge roller 1H16.

  The waste toner box 1H21 is a container for collecting a pattern formed on the transfer belt 1H3 or toner remaining on the transfer belt 1H3 without being transferred to the recording medium 1H12.

<Outline of operation of image forming apparatus>
When performing image formation, the image forming apparatus 1 charges the photoreceptors 1H6A, 1H6B, 1H6C, and 1H6D of the respective colors by the chargers 1H7A, 1H7B, 1H7C, and 1H7D.

  The exposure device 1H8 emits laser light 1H11A, 1H11B, 1H11C, and 1H11D to the charged photoreceptors 1H6A, 1H6B, 1H6C, and 1H6D to perform exposure, thereby forming an electrostatic latent image.

  The developing devices 1H9A, 1H9B, 1H9C, and 1H9D form toner images by attaching toner to the electrostatic latent images formed on the photoreceptors 1H6A, 1H6B, 1H6C, and 1H6D.

  The toner image is so-called primary transferred by contact between the photoreceptors 1H6A, 1H6B, 1H6C, 1H6D and the transfer belt 1H3. The primary transfer is performed by primary transfer rollers 1H22A, 1H22B, 1H22C, and 1H22D for each color. The toner image is formed on the transfer belt 1H3 by primary transfer.

  After the primary transfer is completed, the toner remaining on the photoreceptors 1H6A, 1H6B, 1H6C, and 1H6D is removed by the cleaner blades 1H10A, 1H10B, 1H10C, and 1H10D.

  The toner image formed by the developing unit 1H1A is conveyed to the next developing unit 1H1B by the transfer belt 1H3. Similarly, the developing units 1H1B, 1H1C, and 1H1D perform transfer so that the toner images of the respective colors are superimposed. A full-color toner image is formed by the developing units 1H1A, 1H1B, 1H1C, and 1H1D.

  The full-color toner image formed on the transfer belt 1H3 is conveyed to the secondary transfer roller 1H18 that performs secondary transfer by the transfer belt 1H3.

  The recording medium 1H12 is conveyed from the paper feed tray 1H13 to the registration roller 1H15 by the paper feed roller 1H14. The conveyed recording medium 1H12 is conveyed to a secondary transfer roller 1H18 that performs secondary transfer by a registration roller 1H15.

  The conveyance of the recording medium 1H12 by the registration roller 1H15 and the conveyance of the toner image by the transfer belt 1H3 are performed at a timing at which the toner image is transferred to a predetermined position on the recording medium 1H12. That is, the registration roller 1H15 and the transfer belt driving roller 1H4 start driving at the timing at which the recording medium 1H12 and the toner image overlap at the point of the secondary transfer roller 1H18 that performs the secondary transfer.

  The toner image on the transfer belt 1H3 is secondarily transferred to the recording medium 1H12 conveyed by the registration roller 1H15 by the secondary transfer roller 1H18. The recording medium 1H12 on which the secondary transfer has been performed is subjected to fixing processing such as pressurization and heating by a fixing device 1H19.

  The recording medium 1H12 on which the fixing process has been performed is conveyed to a paper discharge tray 1H26 outside the image forming apparatus 1 by a paper discharge roller 1H16.

  In the case of so-called double-sided printing, the recording medium 1H12 subjected to the fixing process is conveyed to the registration roller 1H15 by the double-sided roller 1H17. The recording medium 1H12 conveyed to the registration roller 1H15 is conveyed again by the registration roller 1H15. The recording medium 1H12 conveyed again by the registration roller 1H15 is subjected to secondary transfer and fixing processes on the surface on which no previous image formation has been performed. The recording medium 1H12 on which the fixing process has been performed is conveyed to a paper discharge tray 1H26 outside the image forming apparatus 1 by a paper discharge roller 1H16.

  Each color developing unit 1H1A, 1H1B, 1H1C, 1H1D has a toner amount sensor (not shown) for detecting the toner amount. It is determined whether or not the toner amount in the developing unit is equal to or less than a predetermined amount by a toner amount sensor. When it is determined by the determination that the toner amount in the developing unit is equal to or less than a predetermined amount, toner is supplied from the toner containers 1H2A, 1H2B, 1H2C, and 1H2D for each color.

  The thickness sensor 1H27 measures the thickness of the recording medium 1H12 that passes through the location where the thickness sensor 1H27 is installed. Details of the measurement by the thickness sensor 1H27 will be described later.

  The paper discharge roller solenoid 1H28 is used to change the rotation direction of the paper discharge roller 1H16 and the paper discharge direction. Details of the discharge roller solenoid 1H28 will be described later.

<Hardware configuration>
FIG. 2 is a block diagram illustrating an example of a hardware configuration of the image forming apparatus according to the embodiment of the present invention.

  The image forming apparatus 1 includes a CPU (Central Processing Unit) 1D1, a storage device 1D2, a control device 1D3, and an image processing IC (Integrated Circuit) 1D4. The image forming apparatus 1 includes a sensor 1D5, an actuator 1D6, and an operation panel 1D7.

  The controller 1D41 is connected to the image processing IC 1D4. The operation panel 1D7 is connected to an operation panel I / F (Interface) 1D71. Each component of the image forming apparatus 1 is connected by a bus 1D8 to transmit / receive data or signals to / from each other.

  The image forming apparatus 1 has, for example, an electronic circuit board (not shown), and realizes a hardware configuration as shown in FIG. 2 on the electronic circuit board. Each component may be composed of a plurality of electronic circuit boards or devices connected by wiring or the like.

  The CPU 1D1 performs various processes performed by the image forming apparatus 1. For example, the CPU 1D1 acquires data or a program stored from a storage device 1D2 described later via the bus 1D8. The CPU 1D1 outputs commands, parameters, and the like to the control device 1D3 and the image processing IC 1D4, which will be described later, via the bus 1D8. In order to control the entire image forming apparatus 1, the CPU 1D1 performs various controls such as acquisition of a measurement result of a sensor 1D5 described later and control of an actuator 1D6 described later.

  For example, the controller 1D41 transmits image data to the image processing IC 1D4. For example, the image processing IC 1D4 calculates the toner consumption based on the image data transmitted from the controller 1D41, and transmits the toner consumption to the CPU 1D1.

  The CPU 1D1 may be composed of a plurality of devices or a plurality of cores in order to increase the speed by parallel processing. In addition, the processing by the CPU 1D1 is distributed or performed in parallel by the image forming apparatus 1 having another hardware resource (not shown) such as an auxiliary IC inside or outside and assisting the CPU 1D1. It may be done.

  The storage device 1D2 is a so-called main storage device or auxiliary storage device having a storage area and a control device such as a memory (Memory), a register, or an HD (Hard Disk). The storage device 1D2 stores information such as various data, parameters, or programs including intermediate results of processing based on the control of the CPU 1D1, for example. The storage device 1D2 may be composed of a plurality of devices. The storage device 1D2 may have a configuration in which, for example, a storage device that stores a control program or the like and a so-called main storage device or a so-called work memory are separate devices. The storage device 1D2 may have a configuration in which a storage device is individually provided depending on, for example, the intended use or the type of data to be stored.

  The control device 1D3 controls various devices included in the image forming apparatus 1. The control device 1D3 includes, for example, a sensing control device 1D31 and a drive control device 1D32.

  The sensing control device 1D31 controls the sensor 1D5. The drive control device 1D32 controls the actuator 1D6.

  The sensor 1D5 is, for example, the paper discharge sensor 1H20, the registration sensor 1H23, the recording medium amount sensor 1H24, the double-sided sensor 1H25, and the thickness sensor 1H27 in FIG. Each sensor detects the presence or absence of the recording medium 1H12 or measures the recording medium 1H12.

  When the recording medium 1H12 is conveyed to the registration roller 1H15 in FIG. 1, for example, the registration sensor 1H23 outputs a signal having a predetermined potential. The sensing control device 1D31 performs processing such as A / D conversion. The sensing control device 1D31 detects whether or not the recording medium 1H12 is conveyed to the registration roller 1H15 in FIG. 1 based on whether or not the signal output from the registration sensor 1H23 is equal to or higher than a predetermined potential.

  Similarly, the paper discharge sensor 1H20 and the sensing control device 1D31 in FIG. 1 detect whether or not the recording medium 1H12 is conveyed to the paper discharge roller 1H16 in FIG.

  The double-sided sensor 1H25 and the sensing control device 1D31 in FIG. 1 detect whether or not the recording medium 1H12 is conveyed to the double-sided roller 1H17 in FIG.

  The recording medium amount sensor 1H24 and the sensing control device 1D31 in FIG. 1 measure the number of recording media 1H12 accommodated in the paper feed tray 1H13 in FIG.

  The sensor 1D5 may be configured to measure other environments. For example, the image forming apparatus 1 may have a sensor (not shown) that measures temperature or humidity at various locations inside, and may change parameters of each process based on the measured temperature or humidity.

  The thickness sensor 1H27 measures the thickness of the recording medium 1H12. The thickness sensor 1H27 measures the thickness of the recording medium 1H12 by a method such as ultrasonic, light, contact, or magnetism. The embodiment is not limited to the thickness sensor measurement method.

  Details of the measurement by the thickness sensor 1H27 will be described later.

  The actuator 1D6 is, for example, a motor (not shown) that rotates the paper feed roller 1H14, a motor (not shown) that rotates the registration roller 1H15, and a paper discharge roller solenoid 1H28.

  The operation panel 1D7 is a device for inputting an operation on the image forming apparatus 1 by the user. The operation panel 1D7 is, for example, a so-called touch panel.

  The operation panel I / F 1D 71 converts a signal input from the operation panel 1D7 into a format that can be used in subsequent processing, for example, A / D conversion, and outputs the result to the CPU 1D1 via the bus 1D8.

  For example, the user performs various settings of the image forming apparatus 1 using the operation panel 1D7.

  The embodiment is not limited to the hardware configuration illustrated in FIG. For example, components of the hardware configuration may be added or removed according to the function of the image forming apparatus 1.

<Functional configuration>
FIG. 3 is a functional block diagram illustrating an example of a functional configuration of the image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus 1 includes an image forming unit 1F1, a transport unit 1F2, a control unit 1F3, and a measurement unit 1F4.

  The image forming unit 1F1 performs various processes such as charging / discharging, exposure, development, transfer, fixing, and cleaning for forming an image on the recording medium 1H12. Various processes are realized by each component of the image forming apparatus 1. For example, the development is realized by the developing devices 1H9A, 1H9B, 1H9C, and 1H9D for each color.

  The image forming unit 1F1 includes a fixing unit 1F11. The fixing unit 1F11 performs fixing in image formation. In the fixing unit 1F11, for example, the recording medium 1H12 subjected to the secondary transfer by the secondary transfer roller 1H18 in FIG. 1 is conveyed to the fixing device 1H19 in FIG. 1, and the fixing is performed by the fixing device 1H19 in FIG. The fixed recording medium 1H12 is subjected to a discharge process described later or a transport process described later for image formation on both sides.

  The fixing unit 1F11 controls a secondary transfer process which is a pre-process of the fixing process. For example, the fixing unit 1F11 controls the current applied to the secondary transfer roller 1H18 in FIG.

  The image forming unit 1F1 is controlled by a control unit 1F3 described later.

  The transport unit 1F2 transports the recording medium 1H12. The transport unit 1F2 includes a first transport unit 1F21 and a second transport unit 1F22.

  The first transport unit is realized by, for example, the first transport unit 1F21. Hereinafter, the example by the 1st conveyance part 1F21 is demonstrated.

  The first transport unit 1F21 is realized by, for example, the double-sided roller 1H17 in FIG. The first transport unit 1F21 is a mechanism for performing transport during so-called double-sided printing, in which image formation is performed on both one surface and the other surface of the recording medium 1H12. The double-sided roller 1H17 in FIG. 1 is not limited to the arrangement or configuration shown in FIG. For example, the double-sided roller 1H17 in FIG. 1 may be arranged other than the position shown in FIG. 1, or may be configured by a plurality of rollers (not shown).

  The first transport unit 1F21 transports the recording medium 1H12 to the image forming unit 1F1 again when the image forming unit 1F1 forms an image on one side in order to form an image on both sides of the recording medium 1H12. For example, when an image is formed on one surface of the recording medium 1H12, the recording medium 1H12 is conveyed from the fixing device 1H19 in FIG. The first transport unit 1F21 transports the recording medium 1H12 transported from the fixing device 1H19 in FIG. 1 to the secondary transfer roller 1H18 in FIG. 1 through the registration roller 1H15 in FIG.

  In the case of duplex printing, the conveyance path of the recording medium 1H12 by the first conveyance unit 1F21 is not limited to the conveyance path shown in FIG. For example, at the time of duplex printing, the recording medium 1H12 may be conveyed to the image forming unit 1F1 through a path other than the path described in FIG.

  The second transport unit is realized by, for example, the second transport unit 1F22. Hereinafter, the example by the 2nd conveyance part 1F22 is demonstrated.

  The second transport unit 1F22 is realized by, for example, the paper discharge roller 1H16 in FIG.

  The second transport unit 1F22 performs a discharge process for discharging the recording medium 1H12 from the image forming apparatus 1. The discharge process is a process for conveying the recording medium 1H12 to the paper discharge tray 1H26 in FIG. 1 by the paper discharge roller 1H16 in FIG.

  The second transport unit 1F22 performs a transport process for transporting the recording medium 1H12 to the double-sided roller 1H17 in FIG. The conveyance process is a process for conveying the recording medium 1H12 to the double-sided roller 1H17 in FIG. 1 by the paper discharge roller 1H16 in FIG.

  The second transport unit 1F22 realizes a switching process for switching between a discharge process and a transport process, for example, by switching the rotation direction of the paper discharge roller 1H16 in FIG. The switching process is realized by the control unit 1F3 described later.

  Details of the switching process, the discharge process, and the transport process will be described later.

  The transport unit 1F2 is controlled by a control unit 1F3 described later. For example, the transport unit 1F2 transports the recording medium 1H12 from the paper feed tray of FIG. 1 by the paper feed roller 1H14 of FIG.

  The control unit 1F3 controls each element of the image forming apparatus 1. The control unit 1F3 is realized by the CPU 1D1 in FIG. 2 and the control device 1D3 in FIG. The control unit 1F3 may perform control based on a user operation input from the operation panel 1D7 in FIG. 2 or a command from the image processing IC 1D4 in FIG.

  The control unit 1F3 acquires data used for control or information such as parameters from the measurement unit 1F4 described later, and performs control based on the acquired information.

  The control unit 1F3 includes, for example, a switching control unit 1F31 and a fixing control unit 1F32.

  The switching control unit 1F31 performs a switching process to be described later on the second transport unit 1F22.

  The fixing control unit 1F32 controls the fixing unit 1F11, which will be described later. The fixing control unit 1F32 may control the secondary transfer process by the fixing unit 1F11.

  The measurement unit 1F4 measures the recording medium 1H12 with various sensors. The measurement unit 1F4 is realized by, for example, the sensor 1D5 and the sensing control device 1D31 in FIG. The measurement unit 1F4 is controlled by the control unit 1F3.

  The measurement unit 1F4 measures the thickness of the recording medium 1H12, for example. The measuring unit 1F4 measures the thickness of the recording medium 1H12 by the thickness sensor 1H27 in FIG. 1, and outputs measurement results such as data indicating the measured thickness. The measurement result is transmitted to, for example, the CPU 1D1 in FIG. 2, and is used to indicate a state of the recording medium 1H12, a change in thickness, or the like. Details of the thickness measurement will be described later.

<Measurement of thickness>
FIG. 4 is a diagram illustrating an example of thickness measurement by the measurement unit according to an embodiment of the present invention.

  FIG. 4 corresponds to the thickness sensor peripheral region 1A of FIG. FIG. 4 is an example of the configuration of the measurement unit 1F4 of FIG.

  FIG. 4A is a diagram illustrating an example of a configuration for measuring thickness.

  As shown in FIG. 4A, the thickness sensor 1H27 is disposed, for example, at a position between the registration sensor 1H23 and the paper feed roller 1H14. The arrangement is desirably a position where measurement is possible for any recording medium 1H12 in the case of conveyance from the double-sided roller 1H17 in FIG. 1 and in the case of conveyance from the paper feed tray 1H13 in FIG.

  The thickness sensor 1H27 measures the thickness of the recording medium 1H12 conveyed from the paper feed tray 1H13 in FIG. 1 to the registration roller 1H15. The thickness sensor 1H27 in FIG. 1 measures the thickness of the recording medium 1H12 conveyed from the double-sided roller 1H17 in FIG. 1 to the registration roller 1H15. The measurement result is transmitted as data to the CPU 1D1 of FIG. 2 by, for example, wiring (not shown).

  FIG. 4B is a diagram for explaining an example of thickness measurement at the time of double feeding.

  FIG. 4B shows an example of the double feed in which the two recording media 1H12A and 1H12B are conveyed by the paper feed roller 1H14 from the paper feed tray 1H13 in FIG. Double feed occurs, for example, when the hardness or surface roughness of the recording medium 1H12 is other than the recommended value.

  FIG. 4B shows a case where the recording medium 1H12A and the recording medium 1H12B are shifted and overlapped in the transport direction as illustrated. Hereinafter, the case of double feeding shown in FIG. 4B will be described as an example. Note that double feeding is not limited to the case shown in FIG. The double feeding may be performed, for example, when the recording medium 1H12A and the recording medium 1H12B are transported so that the ends of the recording media coincide with each other, or when three or more recording media overlap.

  FIG. 5 is a diagram for explaining an example of a measurement result by thickness measurement according to an embodiment of the present invention.

  FIG. 5 is an example of a measurement result by the measurement unit 1F4 of FIG. 3 in the case of the double feed described with reference to FIG.

  The measurement unit 1F4 in FIG. 3 measures the thickness of the recording medium 1H12 conveyed through the location where the thickness sensor 1H27 in FIG. 4 is arranged as shown in FIG.

  In the case of double feed in which the two recording media 1H12A and 1H12B are shifted and overlapped, the measurement result of the thickness changes as shown in FIG.

  The measurement time L3 is the time during which the double-feed recording medium 1H12A and the recording medium 1H12B pass through the location where the thickness sensor 1H27 in FIG. 4 is disposed.

  Of the measurement time L3, the constant measurement time L1 during which the predetermined thickness is measured is when only the recording medium 1H12A passes through the location where the thickness sensor 1H27 of FIG. 4 is disposed. Since the recording medium 1H12A and the recording medium 1H12B are shifted and overlapped, the thickness H1 of one recording medium 1H12 is measured at the measurement time L1.

  The predetermined thickness is, for example, the thickness H1 of one recording medium 1H12. Hereinafter, a case where the predetermined thickness is the thickness H1 of one recording medium 1H12 will be described as an example. The recording medium 1H12A and the recording medium 1H12B will be described as an example in which the recording medium has a thickness of H1.

  When the predetermined thickness is the thickness H1 of one sheet of the recording medium 1H12, the measurement unit 1F4 in FIG. 3 calculates a thickness portion that is equal to or greater than the predetermined thickness by measuring the thickness.

  The measurement time L2 is a thickness portion that is equal to or greater than a predetermined thickness where the multi-feed recording medium 1H12A and the recording medium 1H12B overlap. Since the recording medium 1H12A and the recording medium 1H12B overlap each other, the thickness portion is a place where the thickness H2 of two sheets of the recording medium 1H12 is measured.

  After the measurement time L2, the location of the measurement time L4 is measured. In the measurement time L4, since the recording medium 1H12A and the recording medium 1H12B are shifted and overlapped, the thickness H1 of one recording medium 1H12 is measured.

  The measurement time L4 may be calculated from the measurement time L2 by measuring the length of the recording medium 1H12 in advance. Further, the measurement time L1 and the measurement time L4 may be the same, and the measurement time L2 or L4 may be calculated from the measurement time L1.

  2 having received the measurement result, for example, the measurement result indicates that the thickness is one or less of the recording medium, the recording medium is thicker than one sheet, two or less, or thicker than the two recording media. Determine.

  The determination means is, for example, the CPU 1D1 in FIG. 2, and the case of the CPU 1D1 in FIG. 2 will be described as an example.

  When the measurement result is equal to or less than H1, the thickness is equal to or less than one sheet of the recording medium. Therefore, it is determined that the recording medium 1H12 conveyed to the registration roller 1H15 in FIG.

  When the measurement result is thicker than H1 and less than or equal to H2, the thickness is greater than one and less than two, so there are two recording media 1H12 conveyed to the registration roller 1H15 in FIG. It is determined that there are two double feeds.

  When the measurement result is thicker than H2, the thickness is larger than two recording media, so that it is determined that there are three or more recording media 1H12 conveyed to the registration roller 1H15 in FIG. The

  The measurement result and the determination result are stored, for example, by the storage device 1D2 of FIG.

<Overall processing>
FIG. 6 is a flowchart illustrating an example of overall processing according to an embodiment of the present invention.

  Details of timing and effects of performing each process shown in FIG. 6 will be described later.

  In step S0601, the image forming apparatus 1 performs a process of inputting image data, image forming conditions, recording medium information, and the like by the user's operation using the operation panel 1D7 in FIG. The image data is information such as an image that forms an image on a recording medium from a scanner device (not shown) or another device (not shown) via a network, for example.

  The image forming condition is, for example, information for selecting so-called double-sided printing for forming an image on both sides of a recording medium or so-called single-sided printing for forming an image on one side of a recording medium. The image forming condition is, for example, information on the number of images on which image formation is performed or the number of recording media.

  The recording medium information is information such as the type or size of the recording medium set by the user for image formation. In step S0601, the image forming apparatus 1 receives information and a command for starting image formation. The input information is stored in, for example, the storage device 1D2 in FIG. Step S0601 is realized by, for example, the controller 1D41 of FIG.

  In step S0602, the image forming apparatus 1 performs processing up to the primary transfer. Processing up to the primary transfer is performed based on information such as the image data input in step S0601. The processes up to the primary transfer are charging / discharging, exposure, development, and primary transfer in the image forming process performed by the image forming unit 1F1 in FIG.

  Specifically, in step S0602, the image forming unit 1F1 in FIG. 3 forms an electrostatic latent image on the photoreceptors 1H6A, 1H6B, 1H6C, and 1H6D for each color based on the image data input in step S0601, for example. To do. The image forming unit 1F1 in FIG. 3 performs primary transfer for forming a toner image on the transfer belt 1H3 in FIG. 1 based on the formed electrostatic latent image.

  In step S0603, the transport unit 1F2 in FIG. 3 performs a process of transporting the recording medium from the paper feed tray. The transport unit 1F2 in FIG. 3 transports the recording medium 1H12 accommodated in the paper feed tray 1H13 in FIG. 1 by the paper feed roller 1H14 in FIG. The transported recording medium 1H12 passes through the thickness sensor 1H27 in FIG. 1 and is transported to the registration roller 1H15 in FIG.

  Note that the process of step S0603 is performed in accordance with the process of step S0602. The process in step S0603 is performed in parallel with the process in step S0602, for example, and is performed so that the recording medium 1H12 is conveyed to the secondary transfer roller 1H18 in FIG. Is adjusted. It is detected by the registration sensor 1H23 in FIG. 1 whether or not it has been conveyed to the registration roller 1H15 in FIG. The recording medium 1H12 detected by the registration sensor 1H23 in FIG. 1 is adjusted in conveyance timing by rotating the registration roller 1H15 in FIG. 1 at a predetermined timing.

  In step S0604, the measurement unit 1F4 in FIG. 3 performs a thickness measurement process. The thickness measurement process is, for example, the process described with reference to FIG. In step S0604, the measurement unit 1F4 of FIG. 3 measures the recording medium 1H12 conveyed in the process of step S0603. The process of step S0604 generates, for example, the measurement result described with reference to FIG.

  In step S0605, the image forming unit 1F1 and the conveyance unit 1F2 in FIG. 3 perform a secondary transfer process. The image forming unit 1F1 in FIG. 3 conveys the toner image formed in step S0602 to the secondary transfer roller 1H18 in FIG. 1 by the transfer belt 1H3 in FIG. The conveyance unit 1F2 in FIG. 3 conveys the recording medium 1H12 conveyed to the registration roller 1H15 in FIG. 1 in step S0603 to the secondary transfer roller 1H18 in FIG. 1 by the registration roller 1H15 in FIG. The secondary transfer roller 1H18 in FIG. 1 presses and transfers the toner image to the recording medium 1H12. A predetermined current is applied to the secondary transfer roller 1H18 in FIG. The applied current may be variable based on the information input in step S0601.

  The toner image conveyed by the image forming unit 1F1 in FIG. 3 is subjected to secondary transfer processing to be transferred to the recording medium 1H12 conveyed by the conveyance unit 1F2 in FIG. 3 by the secondary transfer roller 1H18 in FIG. The recording medium 1H12 that has been subjected to the secondary transfer process is conveyed to the fixing device 1H19 in FIG. 1 for a fixing process to be described later.

  In step S0606, the fixing unit 1F11 of FIG. 3 performs a fixing process. The fixing process is a process for adhering toner to a recording medium to develop color or gloss. In the fixing process, a so-called nip (Nip) is performed in which the recording medium 1H12 conveyed in step S0605 is pressed by a fixing roller or the like. In the fixing process, the recording medium 1H12 is heated at a fixing temperature to be described later in the nip. In the fixing process, the pressurized and heated recording medium 1H12 is cooled (including natural cooling) to solidify the toner.

  The fixing process includes a process of controlling the fixing unit 1F11 of FIG. 3 by the fixing control unit 1F32 of FIG. 3 and a process of controlling a secondary transfer process as a pre-process of the fixing process. Details of fixing control, which is processing for controlling the fixing unit 1F11 of FIG. 3, will be described later.

  The recording medium 1H12 subjected to the fixing process is conveyed to the paper discharge roller 1H16 in FIG.

  In step S0607, the CPU 1D1 in FIG. 2 determines whether or not double-feed and so-called single-sided printing is performed. The CPU 1D1 in FIG. 2 determines whether or not single-sided printing is performed based on the image forming conditions input in step S0601, for example. The CPU 1D1 in FIG. 2 determines whether or not it is a double feed based on the measurement result generated in step S0604, for example.

  Note that the timing at which the process of step S0607 is performed is not limited to the timing shown in FIG. The timing at which the process of step S0607 is performed may be performed after the measurement result is generated at step S0604 and before the recording medium 1H12 is conveyed to the paper discharge roller 1H16 of FIG. 1 at step S0606. For example, the processing may be performed in parallel with the processing in step S0606.

  If it is determined in step S0607 that the multi-feed and single-sided printing is performed (YES in step S0607), the second transport unit 1F22 in FIG. 3 performs the process in step S0608. If it is determined in step S0607 that multi-feed and single-sided printing are not performed (NO in step S0607), the second transport unit 1F22 in FIG. 3 performs the process in step S0611.

  In step S0608, the second transport unit 1F22 of FIG. 3 performs a discharge process. Details of the discharge process will be described later.

  In step S0609, the switching control unit 1F31 in FIG. 3 performs a switching process. Details of the switching process will be described later.

  In step S0610, the second transport unit 1F22 of FIG. 3 performs a transport process. Details of the conveyance process will be described later.

  In step S0611, the second transport unit 1F22 in FIG. 3 performs a discharge process, which will be described later, or a process for forming an image on another surface. Step S0611 is a case where it is determined in step S0607 that double feeding and single-sided printing are not performed, that is, double-sided printing or multi-feeding is not performed.

  In the case of non-double feeding and single-sided printing, in step S0611, the second transport unit 1F22 in FIG. 3 performs a discharge process described later. In the case of duplex printing, the second transport unit 1F22 in FIG. 3 performs a process for forming an image on the other surface.

  The process for forming an image on the other side is a process for transporting the recording medium 1H12 to the image forming unit 1F1 in FIG. 3 again in order to form an image on the other side. Specifically, the process for forming an image on the other side is a process for transporting the recording medium on which the image is formed on one side by the second transport unit 1F22 in FIG. 3 to the double-sided roller 1H17 in FIG. . A double-sided roller 1H17 in FIG. 1 conveys the conveyed recording medium 1H12 to the registration roller 1H15 in FIG. 1 through the thickness sensor 1H27 in FIG. 1 in order to form an image on the other side. For image formation on the other surface, for example, the processing described in FIG. 6 is performed on the other surface of the recording medium 1H12 from step S0601.

<Switching process, discharge process, and transport process>
FIG. 7 is a diagram illustrating an example of the switching process, the discharge process, and the transport process according to an embodiment of the present invention.

  FIG. 7A is a detailed diagram illustrating an example of the peripheral configuration of the paper discharge roller 1H16 of FIG. FIG. 7A corresponds to the peripheral region 1B of the paper discharge roller 1H16 in FIG.

  The paper discharge roller 1H16 includes, for example, an upper paper discharge roller 1H161 and a lower paper discharge roller 1H162. The upper paper discharge roller 1H161 and the lower paper discharge roller 1H162 are separately controlled by, for example, the drive control device 1D32 in FIG. 2 and the actuator 1D6 in FIG. Specifically, the upper discharge roller 1H161 and the lower discharge roller 1H162 have different rotation directions at predetermined timings by the drive control device 1D32 and the discharge roller solenoid 1H28 in FIG. Or control to make it the same rotation direction is performed. The control of the rotation direction will be described later. As shown in FIG. 7A, for example, the upper paper discharge roller 1H161 is controlled to switch between a clockwise rotation direction R11 and a counterclockwise rotation direction R12. The lower paper discharge roller 1H162 is controlled to rotate in the rotation direction R2 that is counterclockwise.

  The conveyance of the recording medium 1H12 to the paper discharge roller 1H16 is detected by the paper discharge sensor 1H20 installed near the paper discharge roller 1H16 when the leading edge of the recording medium 1H12 is conveyed to the paper discharge roller 1H16. The paper discharge sensor 1H20 detects which part of the recording medium 1H12 is in contact with the paper discharge roller 1H16.

  Note that the embodiment is not limited to the configuration described in FIG. For example, the lower paper discharge roller 1H162 may be controlled to switch the rotation direction.

  FIG. 7B is a detailed view for explaining an example of the discharge process by the discharge roller 1H16 of FIG. FIG. 7B corresponds to a peripheral region 1B of the paper discharge roller 1H16 of FIG. 1 similar to FIG.

  The discharge process is a process of discharging the recording medium 1H12 from the image forming apparatus 1. As shown in FIG. 7B, the discharge process is a process for controlling the upper paper discharge roller 1H161 to rotate in the rotation direction R11 and the lower paper discharge roller 1H162 in the rotation direction R2, for example. Through the discharge process, the recording medium 1H12 is discharged to the paper discharge tray 1H26 in FIG.

  In the case of double feeding, the number of recording media 1H12 is two or more. The double-feed recording medium 1H12 (the second recording medium is not shown) is discharged to the paper discharge tray 1H26 in FIG.

  The conveyance process is a process for conveying the recording medium 1H12 to the double-sided roller 1H17 in FIG.

  FIG. 7C is a detailed diagram for explaining an example of the conveyance process by the paper discharge roller 1H16 of FIG. FIG. 7C corresponds to a peripheral region 1B of the paper discharge roller 1H16 of FIG. 1 similar to FIG.

  FIG. 7C shows a case where the recording medium is shifted and overlapped in the transport direction between the recording medium 1H12A and the recording medium 1H12B, as in FIG. Hereinafter, the case of double feeding shown in FIG. 7C will be described as an example.

  As shown in FIG. 7C, the conveyance process is a process for controlling the upper discharge roller 1H161 to rotate in the rotation direction R12 and the lower discharge roller 1H162 in the rotation direction R2, for example. As shown in FIG. 7C, the conveyance process is performed at a location where the recording medium 1H12A and the recording medium 1H12B overlap each other.

  The location of the thickness portion is detected by the measurement result of FIG. 5 and the paper discharge sensor 1H20. For example, the location of the thickness portion is the location corresponding to the measurement time L2 in the case of FIG. 5 and when the conveyance speed is constant, and therefore the time L1 after the leading end portion of the recording medium 1H12A passes the paper discharge sensor 1H20. After the lapse.

  FIG. 7D is a detailed diagram illustrating an example of the effect of the conveyance process by the paper discharge roller 1H16 of FIG. FIG. 7D corresponds to a peripheral region 1B of the paper discharge roller 1H16 of FIG. 1 similar to FIG.

  In the double feeding, the conveyance process is a process for discharging the recording medium 1H12A to the paper discharge tray 1H26 in FIG. 1 and conveying the recording medium 1H12A to the double-sided roller 1H17 in FIG. When the conveyance processing is performed, the recording medium 1H12A and the recording medium 1H12B have different conveyance directions according to the rotation direction of the paper discharge roller that is in contact therewith. Therefore, the recording medium 1H12A and the recording medium 1H12B which are double-fed are separated, and the number of cases where the recording media are overlapped can be reduced.

  The recording medium 1H12B is conveyed to the double-sided roller 1H17 in FIG. 1 by the conveyance process. The conveying means for conveying the recording medium to form an image on both sides of the recording medium is, for example, the double-sided roller 1H17 in FIG. Hereinafter, the case of the double-sided roller 1H17 of FIG. 1 will be described as an example. The double-sided roller 1H17 in FIG. 1 conveys, for example, the recording medium 1H12B to the registration roller 1H15 in FIG. The recording medium 1H12B conveyed to the registration roller 1H15 in FIG. 1 is the same as the recording medium conveyed in step S0603 in FIG. 6, and can be used for image formation. Therefore, the user can omit the work of setting the recording medium 1H12B double-fed by the conveyance process on the paper feed tray 1H13 in FIG.

  The switching process is a process of switching between a discharge process and a transport process based on the location of the thickness portion. The switching process is realized by, for example, the switching control unit 1F31 in FIG. The switching process is a process of switching between a discharging process and a conveying process by switching, for example, the rotation direction R11 and the rotation direction R12 of the upper discharge roller 1H161. The switching process is a process of switching from the discharging process of FIG. 7B to the conveying process of FIG. 7C by switching between the rotation direction R11 and the rotation direction R12 of the upper paper discharge roller 1H161.

  Details of the timing at which the switching process is performed will be described later.

<Timing>
FIG. 8 is a timing chart illustrating an example of the timing of overall processing according to an embodiment of the present invention.

  A signal S0801 is a signal indicating the operation of the paper feed roller 1H14 of FIG. In FIG. 8, at the timing T1, the paper feed roller 1H14 in FIG. 1 starts conveying the recording medium 1H12. The process starting from the timing T1 is a process corresponding to step S0603 in FIG. In response to the signal S0801, the paper feed roller 1H14 in FIG. 1 conveys the recording medium 1H12 from the paper feed tray 1H13 in FIG. 1 to the registration roller 1H15 in FIG.

  The signal S0802 is a signal indicating thickness information acquired by the thickness sensor 1H27 of FIG. The information indicated by the signal S0802 is, for example, the measurement result described with reference to FIG. In FIG. 8, a case where the signal S0802 is the same as that in FIG. 5 will be described as an example. The signal S0802 may be, for example, a binary signal indicating whether the recording medium 1H12 is a double feed with the thickness H1 of the recording medium 1H12 as a threshold value. The process related to the signal S0802 corresponds to the process of step S0604 in FIG.

  A signal S0803 is a detection result of the recording medium 1H12 by the registration sensor 1H23 of FIG. For example, when the signal S0803 is High, the recording medium 1H12 is detected, and the recording medium 1H12 is conveyed to the registration roller 1H15 of FIG. 1 by the paper feed roller 1H14 of FIG. When the signal S0803 is Low, the recording medium 1H12 cannot be detected.

  When the signal S0803 is High (T2 to T3), the registration roller 1H15 in FIG. 1 is in a state in which the recording medium 1H12 can be conveyed to the secondary transfer roller 1H18 in FIG. 1, that is, the secondary transfer process is performed. It is ready to start.

  A signal S0804 is a signal indicating the operation of the registration roller 1H15 of FIG. The registration roller 1H15 in FIG. 1 conveys the recording medium 1H12 to the secondary transfer roller 1H18 in FIG. 1 at a timing T4. When the recording medium 1H12 is conveyed to the secondary transfer roller 1H18 in FIG. 1, a secondary transfer process is performed. Since the toner image is transferred to a predetermined position on the recording medium 1H12, the timing of T4 is adjusted according to the transport distance or the like.

  A signal S0805 is a signal indicating the operation of the secondary transfer roller 1H18 of FIG. Secondary transfer processing is performed by the secondary transfer roller 1H18 of FIG. The processing related to the signal S0805 corresponds to the processing in step S0605 in FIG.

  A signal S0806 is a signal indicating the operation of the fixing device 1H19 of FIG. A fixing process described later is performed by the fixing device 1H19 of FIG. The process related to the signal S0806 corresponds to the process of step S0606 in FIG. The signal S0806 may control the current applied to the secondary transfer roller 1H18 in FIG.

  A signal S0807 is a detection result of the recording medium 1H12 by the paper discharge sensor 1H20 of FIG. For example, when the signal S0807 is High (T5 to T6), the recording medium 1H12 is detected, and the recording medium 1H12 is conveyed to the paper discharge roller 1H16 in FIG. 1 by the fixing device 1H19 in FIG. is there. When the signal S0807 is Low, the recording medium 1H12 cannot be detected.

  Signals S0808 and S0809 are signals indicating the operation of the paper discharge roller 1H16 in FIG. The paper discharge roller 1H16 in FIG. 1 performs any one of discharge processing, conveyance processing, and processing for forming an image on another surface.

  In FIG. 8, the case where the recording medium in FIG. 5 and FIG. 7 is a double feed in which the recording medium 1H12A and the recording medium 1H12B overlap and deviate from the transport direction will be described as an example. The paper discharge roller 1H16 in FIG. 1 performs the operation described in FIG. 7, for example. The processing of signals S0808 to S0810 in FIG. 8 is for double feed and single-sided printing (corresponding to YES in step S0607 in FIG. 6).

  A signal S0808 is a signal indicating the operation of the upper paper discharge roller 1H161 in FIG.

  A signal S0809 is a signal indicating the operation of the lower paper discharge roller 1H162 in FIG.

  A signal S0810 is a signal indicating the operation of the paper discharge roller solenoid 1H28. For example, the discharge roller solenoid 1H28 changes the rotation direction of the upper discharge roller 1H161 in FIG. 7 according to the high and low of the signal S0810.

  In the case of T7 to T8, the signal S0808 rotates the upper paper discharge roller 1H161 in FIG. 7 in the rotation direction R11, and the signal S0809 rotates the lower paper discharge roller 1H162 in FIG. 7 in the rotation direction R2. The operations based on the signals S0808 and S0809 from T7 to T8 are discharge processes corresponding to FIG. 7B and step S0608 in FIG. In the case of double feeding, the discharge process is performed at a location where the recording medium 1H12A and the recording medium 1H12B do not overlap. The part which does not overlap is equivalent to the L1 part of the measurement result of FIG.

  In the case of T8 to T9, the signal S0808 rotates the upper paper discharge roller 1H161 in FIG. 7 in the rotation direction R12, and the signal S0809 rotates the lower paper discharge roller 1H162 in FIG. 7 in the rotation direction R2. The operations based on the signals S0808 and S0809 from T8 to T9 are conveyance processes corresponding to FIG. 7D and step S0610 in FIG.

  In the case of double feeding, the location of the thickness portion where the recording medium 1H12A and the recording medium 1H12B overlap is detected based on the measurement result of FIG. T8 is, for example, a case where L1 which is a portion corresponding to L2 has elapsed in the measurement result of FIG. In the case of T8 to T9, the discharge roller solenoid is operated, that is, a switching process is performed. The operation by the signal S0810 from T8 to T9 is a switching process corresponding to step S0609 in FIG. 7C and FIG.

  The operation in response to the signal S0810 from T8 to T9 is a process in which the recording medium is conveyed in different directions by the upper discharge roller 1H161 in FIG. 7 and the lower discharge roller 1H162 in FIG. Specifically, the switching process is a process of changing the rotation direction of the upper discharge roller 1H161 in FIG. 7 from the rotation direction R11 to R12 and maintaining the rotation direction of the lower discharge roller 1H162 in FIG. 7 in the rotation direction R2. is there. In the switching process, the recording medium 1H12A and the recording medium 1H12B by double feeding are separated, and the recording medium is conveyed in different directions.

  In the case of T9 to T10, the signal S0808 rotates the upper paper discharge roller 1H161 in FIG. 7 in the rotation direction R12, and the signal S0809 rotates the lower paper discharge roller 1H162 in FIG. 7 opposite to the rotation direction R2 ( Not shown). In the case of T9 to T10, in the case of double feeding, the recording medium 1H12A and the recording medium 1H12B are separated, and the recording medium 1H12A is discharged to the paper discharge tray 1H26 of FIG. 1 to carry the recording medium 1H12B. It is. The paper discharge roller 1H16 in FIG. 1 conveys the recording medium 1H12B to the double-sided roller 1H17 in FIG.

  Note that the embodiment is not limited to the timing of FIG. For example, T8 may be a location corresponding to the location of L2, and may be after L1 has elapsed from T7.

  By performing the switching process, the discharge process, and the transport process based on the location of the thickness portion, recording is performed without providing a certain distance between the position of the sensor for detecting the overlap of the recording medium and the means for eliminating the overlap of the recording medium. The media can be separated. That is, the image forming apparatus can be reduced in size by performing the switching process, the discharge process, and the transport process based on the thickness portion.

<Fixing control>
FIG. 9 is a diagram illustrating an example of fixing processing and fixing control according to an embodiment of the present invention.

  FIG. 9A is a detailed view of an example of a portion related to the fixing device 1H19 of FIG.

  The fixing device 1H19 performs a fixing process. The fixing process is a process corresponding to the operation related to step S0606 in FIG. 6 and signal S0806 in FIG.

  FIG. 9 illustrates an example of the double feed in which the recording medium 1H12A and the recording medium 1H12B in FIG. 5 and FIG.

  In the fixing device 1H19, the recording medium by double feeding is conveyed from the secondary transfer roller 1H18 of FIG. The fixing device 1H19 conveys the recording medium to the paper discharge roller 1H16 in FIG.

  In the fixing device 1H19, for example, the fixing temperature of the fixing process and the pressure by the fixing roller are controlled based on the type or thickness of the recording medium. Since the information related to the recording medium is input in step S0601 in FIG. 6, the fixing device 1H19 is controlled based on the information related to the recording medium. The fixing device 1H19 is controlled by, for example, the fixing control unit 1F32 in FIG.

  FIG. 9B is a diagram illustrating an example of control of the fixing device 1H19.

  The fixing device 1H19 is controlled based on, for example, the measurement result of FIG. 5, that is, the thickness portion.

  For the control, for example, the first control is performed at a location L1 and L4 where the recording medium 1H12 has a thickness H1 of one sheet, and the second control is performed at a location L2 where the recording medium 1H12 has a thickness H2 of two sheets. It is. The first control and the second control are controls for setting, for example, the fixing temperature of the fixing device 1H19 and the secondary transfer current applied to the secondary transfer roller 1H18 of FIG. 1 in the secondary transfer process.

  FIG. 9C is a diagram illustrating an example of the first control and the second control.

  For example, the first control is a control for setting the fixing temperature to 155 ° C. and the secondary transfer current to 20 μA in the case of L1 and L4 based on the setting table 3. The second control is a control for setting the fixing temperature to 185 ° C. and the secondary transfer current to 45 μA in the case of L2 based on the setting table 3.

  In the case of double feeding, the thickness portion where the recording media overlap has a large thickness because there are two or more recording media. Therefore, the electrical resistance and heat capacity of the recording medium are increased at the thick portion. The first control is a condition set based on the electrical resistance and heat capacity when there is only one recording medium. By performing the processing based on the second control on the location of the thick portion, the transfer and fixing conditions can be optimized and the image quality can be improved.

  By controlling based on the location of the thick portion, the image quality of the image formed on the recording medium can be improved.

  Note that the control is not limited to the control described in FIG. For example, the setting table 3 may be set for each type or thickness of the recording medium, or when there are three or more recording media overlapped by double feeding.

Second Embodiment
The second embodiment uses the image forming apparatus 1 of the first embodiment. Therefore, the description of the image forming apparatus 1 is omitted.

  In the second embodiment, the entire process of FIG. 10 is performed instead of the entire process described in FIG. 6 of the first embodiment.

  FIG. 10 is a flowchart illustrating an example of the overall processing of the second embodiment according to an embodiment of the present invention. The processing described in FIG. 6 according to the first embodiment is denoted by the same reference numerals and names as those in FIG.

  FIG. 10 is different from the case of FIG. 6 of the first embodiment in that the processes of steps S1001 to S1005 are added.

  In step S1001, the control unit 1F3 in FIG. 3 determines whether or not it is stopped by a stop process described later.

  If it is stopped (YES in step S1001), the control unit 1F3 in FIG. 3 proceeds to step S1002. If not stopped (NO in step S1001), the control unit 1F3 in FIG. 3 proceeds to step S0603 and performs control so that the transport unit 1F2 in FIG. 3 performs processing for transporting the recording medium from the paper feed tray. When not stopping, since it is the same as that of FIG. 6 of 1st Embodiment, description is abbreviate | omitted.

  In step S1002, the transport unit 1F2 in FIG. 3 performs a process of waiting for the recording medium transported by the transport unit 1F2 in FIG. The control unit 1F3 in FIG. 3 performs control so that the transport unit 1F2 in FIG. 3 performs a process of waiting for the recording medium that has been transported.

  If it is stopped (YES in step S1001), there is a double feed during the previous image formation, and a switching process, a discharging process, and a conveying process are performed. During the previous image formation, the recording medium 1H12 is transported by the double-sided roller 1H17 of FIG. 1 by the transport process in step S0610. The recording medium to be transported is, for example, the recording medium 1H12B in FIG. The process of step S1002 is a process of waiting for the recording medium 1H12B of FIG. 7D to be conveyed to the registration roller 1H15 of FIG. 1 by the double-sided roller 1H17 of FIG. Whether or not the recording medium 1H12B has been conveyed to the registration roller 1H15 in FIG. 1 is detected by the registration sensor 1H23 in FIG. 1 as a signal S803 in FIG.

  In step S1003, the control unit 1F3 in FIG. 3 performs control to cancel a stop process described later. By the stop process described later, the transport unit 1F2 in FIG. 3 stops the process of transporting the recording medium 1H12 from the paper feed tray 1H13 in FIG. 1 in step S0603. The process for canceling the stop process is a process in which the transport unit 1F2 in FIG. 3 performs a process of transporting the recording medium 1H12 from the paper feed tray 1H13 in FIG. That is, when the process for canceling the stop process is performed, it is determined that the next image formation is not stopped in step S1001 (NO in step S1001).

  In step S1004, the control unit 1F3 in FIG. 3 determines whether the next image formation is performed and double feeding is performed. Whether or not the next image formation is present is determined from the image data input in step S0601, the image formation conditions, or the like. Whether or not it is double feeding is determined from the measurement result of step S0604 in the preceding stage, for example.

  If it is determined that the next image formation is being performed and double feeding is being performed (YES in step S1004), the control unit 1F3 in FIG. 3 proceeds to step S1005. If it is determined that the next image is formed and not double-feed (NO in step S1004), control unit 1F3 in FIG. 3 proceeds to step S0605. Since the processing after step S0605 is the same as that of the first embodiment, the description thereof is omitted.

  In step S1005, the control unit 1F3 in FIG. 3 performs a stop process.

  When it is determined that the next image is formed and double feed is made (YES in step S1004), the print medium is shown in FIG. 1 by the switching process in the subsequent step S0609 and the transport process in S0610. Are conveyed by a double-sided roller 1H17. In the next image formation, the control unit 1F3 in FIG. 3 forms an image on a recording medium conveyed to the double-sided roller 1H17 in FIG. 1 instead of the recording medium 1H12 accommodated in the paper feed tray 1H13 in FIG.

  In the next image formation, the stop process is a process for controlling the transport unit 1F2 of FIG. 3 in step S1002 to wait for the transported recording medium.

  By performing the stop process, the image forming apparatus 1 can perform image formation without jamming. By performing the stop process, it is possible to form an image on the transported recording medium, and to reduce the consumption of the recording medium.

<Third Embodiment>
As in the second embodiment, the third embodiment uses the image forming apparatus 1 of the first embodiment. Therefore, the description of the image forming apparatus 1 is omitted.

  In the third embodiment, instead of the overall process described in FIG. 10 of the second embodiment, the overall process of FIG. 11 is performed.

  FIG. 11 is a flowchart for explaining an example of the overall processing of the third embodiment according to an embodiment of the present invention. The processes described in FIG. 6 of the first embodiment and FIG. 10 of the second embodiment are denoted by the same reference numerals and names as those in FIG. 6 and FIG.

  FIG. 11 is different from the case of FIG. 10 of the second embodiment in that the process of step S1101 is added.

  In step S1101, the control unit 1F3 in FIG. 3 determines whether image formation can be performed during standby. If it is determined that image formation can be performed during standby (YES in step S1101), there is a double feed during the previous image formation, and the recording medium 1H12B in FIG. 7D is conveyed by the processing in step S0610. This is the case. When it is determined that image formation can be performed during standby, the control unit 1F3 in FIG. 3 proceeds to step S0603. That is, image formation is started on the recording medium conveyed from the paper feed tray 1H13 in step S0603 until the recording medium 1H12B of FIG. 7D conveyed by the process of step S0610 is conveyed to the registration roller 1H15 of FIG. To do.

  The image forming apparatus 1 can perform image formation until the recording medium 1H12B in FIG. 7D is conveyed to the registration roller 1H15 in FIG. 1 by the processing in step S1101. Accordingly, image formation can be performed during the time until the recording medium 1H12B in FIG. 7D is conveyed to the registration roller 1H15 in FIG. 1, and the productivity of image formation can be increased.

  If it is determined that image formation is not possible during standby (NO in step S1101), the control unit 1F3 in FIG. 3 proceeds to step S1002. The processing after step S1002 is the same as in the second embodiment, and a description thereof will be omitted.

<Fourth embodiment>
The fourth embodiment uses the image forming apparatus 1 of the first embodiment, as in the second embodiment. Therefore, the description of the image forming apparatus 1 is omitted.

  The fourth embodiment performs the entire process of FIG. 12 instead of the entire process described in FIG. 6 of the first embodiment.

  FIG. 12 is a flowchart illustrating an example of the overall processing of the fourth embodiment according to an embodiment of the present invention.

  The process in FIG. 12 is different from the process described in FIG. 6 in that the processes in steps S1201 and S1202 are added.

  In step S1201, the control unit 1F3 in FIG. 3 determines whether to continue image formation or whether the thickness is two or less.

  Whether or not to continue image formation is determined based on, for example, the image formation conditions input in step S0601. Specifically, the control unit 1F3 in FIG. 3 performs image formation continuously when the image forming condition is two or more images on which image formation is performed or the number of recording media on which image formation is performed is two or more. to decide.

  Whether or not the thickness is two or less is determined based on the measurement result generated in step S0604.

  When image formation is continuously performed, or when the thickness is two or less (YES in step S1201), the control unit 1F3 in FIG. 3 proceeds to step S0608. When image formation is not performed continuously, or when the thickness is not two or less (NO in step S1201), control unit 1F3 in FIG. 3 proceeds to step S1202.

  In step S1202, the second transport unit 1F22 in FIG. 3 performs a discharge process. The process in step S1202 is the same as the process in step S0608, and a description thereof will be omitted.

  When the image formation is not performed subsequently, the image formation is not performed next, so that the recording medium is not used subsequently. Therefore, even if the recording medium that has been double-fed by the process of step S0609 is separated, it is not used. Therefore, the process of step S0609 is not performed and the recording medium is discharged out of the image forming apparatus 1.

  The case where the thickness is not two or less is, for example, a case where three recording media are overlapped by double feeding. In the case of double feeding in which three recording media are stacked, the second transport unit 1F22 in FIG. 3 performs the discharge process, does not perform the process of step S0609, and the like, and the recording medium double-fed outside the image forming apparatus 1 Is discharged.

  When image formation is not performed continuously, or when the thickness is not two or less, the recording medium that has been multi-fed is discharged out of the image forming apparatus 1, so that the consumption of the recording medium can be reduced. Further, when image formation is not continuously performed, or when the thickness is not two or less, the double-fed recording medium is discharged out of the image forming apparatus 1, so that it is not a so-called jam. Can be shortened.

<Fifth Embodiment>
As in the second embodiment, the fifth embodiment uses the image forming apparatus 1 of the first embodiment. Therefore, the description of the image forming apparatus 1 is omitted.

  In the fifth embodiment, the entire process of FIG. 13 is performed instead of the entire process described in FIG. 6 of the first embodiment.

  FIG. 13 is a flowchart illustrating an example of the overall processing of the fifth embodiment according to an embodiment of the present invention.

  The process in FIG. 13 is different from the process described in FIG. 6 in that the processes in steps S1301 to S1303 are added.

  In step S <b> 1301, the measurement unit 1 </ b> F <b> 4 of FIG. The recording medium 1H12B passes through the position where the thickness sensor 1H27 is disposed by the double-sided roller 1H17 in FIG. 1 and is transported to the registration sensor 1H23 in FIG. 1 by the transport processing in S0610. In step S1301, the measurement unit 1F4 in FIG. 3 performs the same processing as in step S0604, and generates the measurement result described in FIG. 5, for example.

  In step S1302, the CPU 1D1 in FIG. 2 determines whether or not double feeding is performed. CPU1D1 of FIG. 2 determines whether it is double feeding based on the measurement result produced | generated by step S1301, for example.

  If it is determined that it is a double feed (YES in step S1302), the image forming apparatus 1 proceeds to step S1303. If it is determined that the feeding is not double feeding (NO in step S1302), the image forming apparatus 1 ends the overall processing.

  In step S <b> 1303, the image forming apparatus 1 performs a process of discharging the recording medium to the outside of the image forming apparatus 1. If it is determined in step S1302 that the multi-feed is performed, the recording medium on which the processing in steps S0608 to S0610 has been performed in the preceding stage is multi-feed.

  By discharging the double-fed recording medium to the outside of the image forming apparatus 1 without using it for image formation, it is possible to reduce the mixture of recording media in the recording medium discharge direction, so-called face-up and face-down. Can do.

<Sixth Embodiment>
The sixth embodiment uses the image forming apparatus 1 of the first embodiment, as in the second embodiment. Therefore, the description of the image forming apparatus 1 is omitted.

  In the sixth embodiment, the entire process of FIG. 14 is performed instead of the entire process described in FIG. 6 of the first embodiment.

  FIG. 14 is a flowchart for explaining an example of the overall processing of the sixth embodiment according to the embodiment of the present invention.

  The process of FIG. 14 differs from the process described in FIG. 6 in that the processes of steps S1401 and S1402 are added.

  In step S1401, the CPU 1D1 in FIG. 2 determines whether or not the recording medium has been conveyed to the registration rollers within a predetermined time.

  The predetermined time is a time arbitrarily set by an administrator of the image forming apparatus 1 or the like. For example, the predetermined time is a value obtained by dividing the distance from the paper discharge roller 1H16 to the registration roller 1H15 by the conveyance speed.

  If it is determined that the recording medium has not been conveyed to the registration roller 1H15 within the predetermined time (NO in step S1401), the image forming apparatus 1 proceeds to step S1402. If it is determined that the recording medium has been conveyed to the registration roller 1H15 within a predetermined time (YES in step S1401), the image forming apparatus 1 ends the entire process.

  In step S1402, the image forming apparatus 1 performs a process of ending the conveyance process. The process for ending the conveyance process is a process for stopping the actuators of the paper discharge roller 1H16 and the double-sided roller 1H17, for example.

  The process in step S1402 is performed when the processes in steps S0608 to S0610 are performed during double feeding. When the processing from step S0608 to step S0610 is performed, the recording medium 1H12B in FIG. 7 is conveyed to the registration roller 1H15 by the double-sided roller 1H17. However, for example, the recording medium 1H12B of FIG. 7 may not be conveyed to the double-sided roller 1H17 but may be discharged to the paper discharge tray 1H26 in the processing from step S0608 to step S0610. The process of step S1401 is a process of determining that the recording medium 1H12B in FIG. 7 is discharged to the discharge tray 1H26 when the recording medium is not conveyed to the registration rollers within a predetermined time. When the paper is discharged to the paper discharge tray 1H26, for example, the frictional force generated between the recording medium 1H12A and the recording medium 1H12B in FIG. 7 is large.

  When discharged to the discharge tray 1H26, it can be determined that an abnormality has occurred in the image forming apparatus 1. By determining when the recording medium is not conveyed to the registration rollers within a predetermined time, the abnormal state of the image forming apparatus 1 can be detected.

  Further, in the sixth embodiment, the image forming process can be continued with the image forming apparatus 1 in an abnormal state.

<Seventh embodiment>
The seventh embodiment uses an image forming apparatus 10 shown in FIG. The image forming apparatus 10 according to the seventh embodiment is different from the image forming apparatus 1 according to the first embodiment in the configuration around the paper discharge tray 1H26 and the paper discharge tray 1H26.

  FIG. 15 is a diagram illustrating an example of the overall configuration of the image forming apparatus according to the seventh embodiment of the present invention.

  The paper discharge tray 1H26 of the image forming apparatus 10 includes a lower tray 1H261 and an upper tray 1H262 as illustrated in the figure. The paper discharge tray 1H26 is not limited to two stages. For example, it may have three or more trays.

  The paper discharge tray 1H26 is a so-called bin having a plurality of stages. Hereinafter, the case where the paper discharge tray 1H26 is composed of a lower tray 1H261 and an upper tray 1H262, which are upper and lower two stages, will be described as an example.

  When discharging the double-fed recording medium, the image forming apparatus 10 performs a process of changing the recording medium on which the image is formed and the tray to be discharged.

  For example, in the process of step S1202 of FIG. 12 of the fourth embodiment, when three or more recording media are double-fed, the recording media are discharged to the paper discharge tray 1H26. In the process of step S1303 in FIG. 13 of the fifth embodiment, when the recording medium is double-fed, the recording medium is discharged to the paper discharge tray 1H26.

  When image formation is not performed on the recording medium 1H12B in FIG. 7 conveyed by the processing in steps S0608 to S0610 in FIG. 6 of the first embodiment, the recording medium 1H12B in FIG. 7 is discharged to the discharge tray 1H26. A case where image formation is not performed on the recording medium 1H12B of FIG. 7 is, for example, a case where the user of the image forming apparatus 10 operates.

  Hereinafter, the case of the fourth embodiment will be described as an example.

  FIG. 16 is a flowchart for explaining an example of the overall processing of the seventh embodiment according to the embodiment of the present invention.

  FIG. 16 differs from FIG. 12 in that the processing of step S1601 and step S1602 is added.

  In step S1601, the control unit 1F3 in FIG. 3 performs processing to set the discharge destination to the lower tray 1H261. By the process of setting the discharge destination to the lower tray 1H261, the recording medium discharged in the discharge process of the subsequent steps S0608 and S0611 is discharged to the lower tray 1H261.

  In step S1602, the control unit 1F3 in FIG. 3 performs processing for setting the discharge destination to the upper tray 1H262. By the process of setting the discharge destination to the upper tray 1H262, the recording medium discharged in the discharge process of the subsequent step S1202 is discharged to the upper tray 1H262.

  The control unit 1F3 in FIG. 3 changes the lower tray 1H261 and the upper tray 1H262, which are discharge destinations, by controlling, for example, a switching solenoid (not shown).

  By the process of changing the discharge destination, the double-fed recording medium can be made a different tray from the recording medium on which the image is formed. In other words, the multi-feed recording medium can be separated and discharged from the image forming apparatus 10 by the process of changing the discharge destination.

  The image forming apparatus 1 may be, for example, a facsimile machine, a printing apparatus (printer), a copying machine, or a multifunction machine.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be changed.

1, 10 Image forming apparatus 1H1A, 1H1B, 1H1C, 1H1D Developing unit 1H2A, 1H2B, 1H2C, 1H2D Toner container 1H3 Transfer belt 1H4 Transfer belt drive roller 1H5 Transfer belt tension roller 1H6A, 1H6B, 1H6C, 1H6D Photoconductor 1H7A, 1H7B, 1H7C, 1H7D Charger 1H8 Exposing device 1H9A, 1H9B, 1H9C, 1H9D Developer 1H10A, 1H10B, 1H10C, 1H10D Cleaner blade 1H11A, 1H11B, 1H11C, 1H11D Laser light 1H12 Recording medium 1H13 Paper feed tray 1H14 Paper feed roller 1H15 Paper discharge roller 1H161 Upper paper discharge roller 1H162 Lower paper discharge roller 1H17 Double-sided roller 1H18 Secondary transfer roller 1H19 Fixing device 1H2 0 Discharge sensor 1H21 Waste toner box 1H22A, 1H22B, 1H22C, 1H22D Primary transfer roller 1H23 Registration sensor 1H24 Recording medium amount sensor 1H25 Duplex sensor 1H26 Discharge tray 1H261 Lower tray 1H262 Upper tray 1H27 Thickness sensor 1H28 Discharge roller solenoid 1D1 CPU
1D2 Storage device 1D3 Control device 1D31 Sensing control device 1D32 Drive control device 1D4 Image processing IC
1D41 Controller 1D5 Sensor 1D6 Actuator 1D7 Operation panel 1D71 Operation panel I / F
1D8 Bus 1F1 Image forming unit 1F11 Fixing unit 1F2 Transporting unit 1F21 First transporting unit 1F22 Second transporting unit 1F3 Control unit 1F31 Switching control unit 1F32 Fixing control unit 1F4 Measuring unit 3 Setting table

JP 2008-013365 A

Claims (10)

An image forming apparatus for forming an image on a recording medium,
Measuring means for measuring the thickness of the recording medium;
First conveying means for conveying the recording medium to form an image on both sides of the recording medium;
A second transport unit that performs a discharge process of discharging the recording medium or a transport process of transporting the recording medium to the first transport unit;
A switching means for performing a switching process for switching the process performed by the second transport means between the discharge process and the transport process;
When a thickness portion that is a predetermined thickness or more is measured by the measuring means,
The switching means is
An image forming apparatus that performs the switching process for switching the process performed by the second transport unit from the discharge process to the transport process based on the location of the thick portion. Fixing means for fixing to the recording medium;
The image forming apparatus according to claim 1, wherein the fixing unit is controlled based on the location of the thick portion. A storage means for storing the recording medium;
When the switching process is performed,
The image forming apparatus according to claim 1, wherein stop processing for stopping processing for transporting the recording medium stored in the storage unit is performed. When the switching process is performed,
The image forming apparatus according to claim 1, wherein an image forming process is performed on the recording medium before the recording medium is conveyed by the first conveying unit. Determining means for determining whether the thickness is one or less of the recording medium, the recording medium is thicker than one sheet or two or less, or thicker than two sheets of the recording medium from the measurement result by the measuring means. Have
If the determination means determines that the recording medium is thicker than two sheets,
The image forming apparatus according to claim 1, wherein predetermined processing is performed. The determination means includes
Determining the recording medium conveyed by the first conveying means;
If it is determined in the determination that the recording medium is thicker than one sheet and not more than two sheets, or thicker than two sheets of the recording medium,
The image forming apparatus according to claim 5, wherein predetermined processing is performed.   The image forming apparatus according to claim 5, wherein the predetermined process is a process of stopping an image forming process.   The image forming apparatus according to claim 5, wherein the predetermined process is a process of stopping an image forming process on both sides of the recording medium.   The image forming apparatus according to claim 5, wherein the predetermined process is a process of stopping an image forming process and changing a discharge direction by the discharge process. An image forming method for causing an image forming apparatus to form an image on a recording medium,
The image forming apparatus includes:
First conveying means for conveying the recording medium to form an image on both sides of the recording medium;
A second transport unit that performs a discharge process for discharging the recording medium or a transport process for transporting the recording medium to the first transport unit;
In the image forming apparatus,
A measurement procedure for measuring the thickness of the recording medium;
A switching procedure for performing a switching process for switching the process by the second transport means between the discharge process and the transport process;
When a thickness portion that is equal to or greater than a predetermined thickness is measured by the measurement procedure,
The switching procedure is as follows:
An image forming method, which is a procedure for performing the switching process for switching the process performed by the second transport unit from the discharge process to the transport process based on the location of the thick portion.

Images