JP2018151595A - Image forming apparatus and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow printing in a short first copy time when sheet setting in advance matches a sheet to be supplied, and allow printing according an appropriate image forming condition when the sheet setting in advance does not match the sheet to be supplied.SOLUTION: A control part of the image forming apparatus causes an image processing part to form a toner image according to an image forming condition according to the current sheet setting, causes a conveying mechanism to start supply of a sheet, determines whether the current sheet setting matches a sheet type of the supplied sheet on the basis of a result of detection from a sheet type detection sensor, when the current sheet setting matches the sheet type of the supplied sheet, continues transferring a toner image formed on the supplied sheet, and when the current sheet setting does not match the sheet type of the supplied sheet, causes the image processing part to form a toner image again according to an image forming condition according to the sheet type of the supplied sheet, and transfers the toner image formed again to the supplied sheet.SELECTED DRAWING: Figure 2

Description

  The present technology relates to an electrophotographic image forming apparatus and a control method in the image forming apparatus.

  An electrophotographic method is widely used as an image forming method for a medium. There are various types of media on which an image is to be formed depending on the size, weight (basis weight), paper thickness, presence / absence of surface processing, and the like. Therefore, it is necessary to adapt the characteristics of the medium and the image forming process.

  If the characteristics of the medium and the image forming process do not match, there is a case where the medium is clogged, which is called a jam.

  From the viewpoint of reducing the burden on the user due to such a problem relating to the medium, Japanese Patent Application Laid-Open No. 2007-124040 (Patent Document 1) continues the image forming process when the double feeding of the recording paper is detected. An image forming apparatus capable of preventing a reduction in job efficiency and reducing the burden on the user is disclosed.

  Originally, it is preferable to adapt the characteristics of the medium and the image forming process in advance. Otherwise, problems such as no need to fix the image on the medium may occur.

  On the other hand, when there are a plurality of types of media, it is difficult for a user who does not have prior knowledge to make settings for adapting the image forming process. In view of this, Japanese Patent Application Laid-Open No. 2010-191301 (Patent Document 2) discloses a configuration in which image formation is performed under image formation conditions corresponding to the sheet thickness. More specifically, in the image forming apparatus disclosed in Patent Document 2, a sheet fed to an image forming unit that forms an image under predetermined image forming conditions is temporarily registered with a registration roller before the image forming unit. After stopping, the sheet is sent out at a predetermined timing and the sheet thickness stopped by the registration roller is detected by a sheet thickness sensor, and the image forming condition in the image forming unit is controlled based on the detection result.

  Japanese Patent Laid-Open No. 2000-305438 (Patent Document 3) discloses a configuration that performs an image forming operation satisfactorily according to the type of transfer material and prevents a reduction in image forming throughput. More specifically, the image forming apparatus disclosed in Patent Document 3 includes a first mode in which an image forming unit forms an image on a photosensitive drum based on the type of transfer material detected by a media detection sensor; Regardless of whether or not the type of the transfer material is detected by the media detection sensor, the second mode in which the image forming unit forms an image on the photosensitive drum based on the detection result detected by the media detection sensor in the first mode. And are selectively switched.

JP 2007-120404 A JP 2010-191301 A JP 2000-305438 A

  The image forming apparatuses disclosed in Patent Document 2 and Patent Document 3 described above are preferable from the viewpoint of reducing the user's labor, but also have the following problems. That is, in the configuration disclosed in Patent Document 2, since image formation is started after the thickness of the paper is detected, even when correct paper setting is performed, FCOT (first copy time), That is, there is a problem that the time required to discharge the first print becomes long.

  Also in Patent Document 3, since the image formation is started after the type of transfer material at the timing when the set value for the type of transfer material is changed, the correct setting is made for the type of transfer material. However, there exists a subject that FCOT becomes long. In addition, when different types of transfer materials are mixed in the same cassette, there is a problem that it cannot be handled.

  This technology is aimed at such a problem, and when the paper settings in advance are suitable for the paper to be supplied, it is possible to print in a short first copy time, and the paper settings in advance. One of the purposes is to enable printing according to appropriate image forming conditions when the paper is not suitable for the supplied paper.

  An image forming apparatus according to an aspect of the present invention includes an image processing unit that forms a toner image according to image forming conditions according to paper settings, a transport mechanism that supplies paper to the image processing unit, and toner formed by the image processing unit. It includes a paper type detection sensor disposed at a stage prior to transferring an image onto a paper, and a control unit that controls the image processing unit and the transport mechanism. The control unit causes the image processing unit to form a toner image according to the image forming condition according to the current paper setting, and causes the transport mechanism to start supplying paper, based on the detection result from the paper type detection sensor, It is determined whether the paper type of the supplied paper and the current paper setting are compatible, and if the paper type of the supplied paper and the current paper setting are compatible, the formed paper for the supplied paper is formed. If the transfer of the toner image continues and the paper type of the supplied paper does not match the current paper setting, the toner image is re-formed according to the image forming conditions according to the paper type of the paper supplied to the image processing unit. Then, the re-formed toner image is transferred to the supplied paper.

  Preferably, the transport mechanism includes a timing roller for supplying paper to the image processing unit, the paper type detection sensor is disposed upstream of the timing roller, and the control unit stops the paper upstream of the timing roller. In this state, a toner image is re-formed.

  Preferably, even when the paper type of the supplied paper and the paper type included in the current paper setting do not match, the control unit is capable of image formation according to the image forming condition according to the current paper setting. In some cases, the transfer of the toner image is continued without re-forming the toner image.

  Preferably, when the paper type of the supplied paper and the current paper setting do not match, the control unit sets the process speed in the image processing unit as the highest process speed among the process speeds set for each paper type. Switch to.

  Preferably, the image processing unit includes a belt carrying the image to be formed and a transfer roller, and the control unit is arranged on the belt when the paper type of the supplied paper and the current paper setting do not match. After the previously formed toner image passes through the transfer roller, the process speed is switched to a speed corresponding to the paper type of the supplied paper.

  Preferably, the image processing unit includes a transfer roller, and the control unit, when the paper type of the supplied paper and the current paper setting do not match, after elapse of a predetermined time required for cleaning the transfer roller, The process speed is switched to a speed corresponding to the paper type of the supplied paper.

  Preferably, when the paper type of the supplied paper does not match the current paper setting and there is a paper that has been processed first, the control unit performs processing for the paper that has been processed earlier. After completion, the process speed in the image processing unit is switched.

  Preferably, the image processing unit includes a transfer roller that can be pressed and separated, and the control unit separates the transfer roller when the paper type of the supplied paper does not match the current paper setting.

  Preferably, when the paper type of the supplied paper and the current paper setting do not match, the control unit changes the paper setting to the user with the paper stopped upstream from the timing roller. Prompt.

  Preferably, the control unit recommends a change to the paper setting corresponding to the paper type of the supplied paper.

  Preferably, when the automatic setting mode in which the image forming condition is determined according to the detection result of the paper type of the supplied paper is selected, the control unit after the detection result by the paper type detection sensor is obtained. Then, the formation of a toner image in the image process unit is started.

  Preferably, when the automatic setting mode is selected, the control unit sets the transport speed for transporting the paper to the detection range of the paper type detection sensor as the lowest speed among the transport speeds set for each paper type. Switch to the transfer speed.

  Preferably, when the automatic setting mode is selected, the control unit maintains the image forming condition corresponding to the detected paper type until the subsequent job is removed until the paper feeding cassette is attached or detached. Process.

  Preferably, even if the automatic setting mode is not selected, the control unit determines whether the paper type of the supplied paper matches the current paper setting based on the detection result from the paper type detection sensor. Judge whether or not.

Preferably, the paper type detection sensor includes a sensor that detects the paper thickness.
Preferably, the sensor for detecting the paper thickness includes a pair of sensors disposed on the printing surface side and the non-printing surface side of the paper, and the pair of sensors are disposed on the conveyance path so as to sandwich the paper by an actuator. Is done.

  According to an aspect of the present invention, a method for controlling an image forming apparatus is provided. The image forming apparatus transfers an image process unit that forms a toner image according to an image forming condition according to a sheet setting, a conveyance mechanism that supplies the sheet to the image process unit, and a toner image formed by the image process unit onto the sheet. And a paper type detection sensor arranged in the previous stage. The control method includes a step of forming a toner image in accordance with an image forming condition according to a current paper setting in the image process unit, starting a paper supply by a transport mechanism, and a detection result from a paper type detection sensor, A step of determining whether the paper type of the supplied paper and the current paper setting are compatible, and formation of the supplied paper when the paper type of the supplied paper and the current paper setting are compatible If the step of continuing the transferred toner image and the paper type of the supplied paper and the current paper setting do not match, the toner according to the image forming condition according to the paper type of the paper supplied to the image process unit And re-forming the image, and transferring the re-formed toner image to the supplied paper.

  According to this technology, if the paper settings in advance are suitable for the paper to be supplied, printing in a short first copy time is possible, and the paper settings in advance are not suitable for the paper to be supplied. In this case, it is possible to perform printing according to appropriate image forming conditions.

It is a cross-sectional schematic diagram which shows the apparatus structure of the image forming apparatus according to this Embodiment. It is a time chart for demonstrating the outline | summary of the image formation process according to this Embodiment. It is a cross-sectional schematic diagram showing a main part configuration in the image forming apparatus according to the present embodiment. It is a schematic diagram which shows an example of the control structure in the image forming apparatus according to this Embodiment. 6 is a diagram showing an example of a user interface screen that prompts a user to change paper settings in the image forming apparatus according to the present embodiment. FIG. It is a time chart for demonstrating the behavior of the principal part in the image formation process according to this Embodiment. It is a flowchart which shows the process sequence which concerns on the image formation process according to this Embodiment. It is a time chart for demonstrating the automatic setting mode of the image forming apparatus according to this Embodiment. FIG. 10 is a diagram for describing a sheet setting state in an automatic setting mode of the image forming apparatus according to the present embodiment. It is a flowchart which shows the process sequence in the automatic setting mode which concerns on the image formation process according to this Embodiment.

  Embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the same or equivalent part in a figure, the same code | symbol is attached | subjected and the description is not repeated.

[A. Device configuration]
First, the configuration of the image forming apparatus according to the embodiment of the present invention will be described. The image forming apparatus may be implemented in any form such as a multi-functional peripheral (MFP), a copier, a facsimile, or a printer.

  FIG. 1 is a schematic cross-sectional view showing an apparatus configuration of image forming apparatus 1 according to the present embodiment. FIG. 1 shows a tandem four-color system as an example of an electrophotographic image forming apparatus. However, the present invention is not limited thereto, and may be a monochrome system or a rotary color system. May be.

  Referring to FIG. 1, an image forming apparatus 1 forms an image on a medium (hereinafter also referred to as “paper S”). The unit 2 includes a sheet holding unit 20 that conveys the paper S, and a fixing device 30 that fixes the toner image transferred to the paper S. As a configuration for controlling these configurations, the image forming apparatus 1 manages the image formation by controlling the control unit 100 that performs overall control, the input unit 110 that receives operations from the user, and the image processing unit 2. And an image forming unit 120.

  The image forming apparatus 1 is, for example, a print job (hereinafter also simply referred to as “job”) from an external terminal device (not shown) connected to a network (typically, a LAN (Local Area Network)). When the execution instruction is received, a color toner image composed of each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the sheet S based on the instruction.

  The image processing unit 2 includes image forming units 10Y, 10M, 10C, and 10K, and an intermediate transfer belt 16 to which the toner images formed by the image forming units 10Y, 10M, 10C, and 10K are transferred. The image forming units 10Y, 10M, 10C, and 10K respectively form Y, M, C, and K single color toner images, and these single color toner images are sequentially stacked via the intermediate transfer belt 16.

  The image forming unit 10Y that forms a toner image with Y-color toner includes a photosensitive drum 11Y, and a charger 12Y, an exposure unit 13Y, and a developing unit 14Y disposed around the photosensitive drum 11Y. The image forming unit 10Y forms a Y-color toner image on the photosensitive drum 11Y through a charging process, an exposure process, and a development process in order. The other image forming units 10M, 10C, and 10K have the same configuration as the image forming unit 10Y, and form M, C, and K toner images on the photosensitive drums 11M, 11C, and 11K, respectively. Formed on the photoconductive drums 11Y, 11M, 11C, and 11K by primary transfer rollers 15Y, 15M, 15C, and 15K that are arranged to face the photoconductive drums 11Y, 11M, 11C, and 11K with the intermediate transfer belt 16 interposed therebetween. Each toner image is multiplex-transferred to the same transfer area on the intermediate transfer belt 16. The toner image that has been multiplex-transferred onto the intermediate transfer belt 16 is transferred from the intermediate transfer belt 16 to the paper S by a pair of secondary transfer rollers 18 disposed at the end of the intermediate transfer belt 16.

  The sheet holding unit 20 includes a paper feed cassette 22 provided below the image processing unit 2. A pair of paper feed rollers 24 arranged in association with the paper feed cassette 22 sequentially supplies the paper S stored in the paper feed cassette 22 along the transport path 28 in association with the image forming process in the image processing unit 2. To do. A pair of timing rollers 26 arranged along the conveyance path 28 controls the timing at which the sheet S is supplied to the pair of secondary transfer rollers 18. The pair of paper feed rollers 24 and the pair of timing rollers 26 correspond to a transport mechanism that supplies paper to the image processing unit 2.

  The sheet S on which the toner image has been transferred by the pair of secondary transfer rollers 18 is transported to the fixing device 30 along the transport path 28. The fixing device 30 fixes the toner image transferred onto the paper S by heating and pressurizing the paper S. The sheet S after the toner image is fixed is discharged onto a discharge tray 34 by a pair of discharge rollers 32.

  The control unit 100, the input unit 110, and the image forming unit 120 are connected so as to communicate with each other. The control unit 100 is responsible for various processes according to the present embodiment as will be described later.

  The control unit 100 controls the image processing unit 2 and a conveyance mechanism for conveying the paper S (a pair of paper feed rollers 24 and a pair of timing rollers 26 and the like) by giving a command from the image forming unit 120 and the like.

  The input unit 110 is realized as a user interface provided on the front surface of the image forming apparatus 1, and typically includes an operation panel including a display display, a touch panel, various input buttons, a display indicator, and the like. The user can also input settings relating to the sheet via the input unit 110.

  The image forming unit 120 generates various commands for forming an image according to the job in accordance with a command from the control unit 100 or the like, and gives the generated command to the image processing unit 2.

  Each of the image forming unit 120 and the control unit 100 includes, as main components, a CPU (Central Processing Unit) that executes a program in a predetermined order and a RAM (Random Access Memory) that provides a working area necessary for executing the program. And a ROM (Read Only Memory) that provides a program. Furthermore, all or part of the image forming unit 120 and / or the control unit 100 may be mounted using a hard wired circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[B. Overview of image forming process according to the present embodiment]
Next, an outline of the image forming process according to the present embodiment will be described.

  In image forming apparatus 1 according to the present embodiment, it is assumed that characteristics such as the size, weight (basis weight), paper thickness, and presence / absence of surface processing are set in advance before the job is executed. The overall settings relating to these sheets are also referred to as “sheet settings” below. That is, in this specification, “paper setting” is a term that collectively refers to one or a plurality of set values related to paper.

  In this specification, the characteristics (size, weight (basis weight), paper thickness, presence / absence of surface processing, etc.) of the paper S that is actually processed are also referred to as “paper type”. That is, the “paper type” is a term including the attribute value of the target paper S.

  In this specification, the “image forming condition” is a collective term for one or more conditions or settings relating to the image forming process, which are adjusted according to the characteristics of the paper S to be processed (that is, paper setting). It is a term.

  FIG. 2 is a time chart for explaining the outline of the image forming process according to the present embodiment. FIG. 2A shows an example of a time chart when the pre-paper setting and the paper type of the paper S that is actually supplied are compatible, and FIG. 2B shows the pre-paper setting. An example of a time chart when the paper type of the paper S actually supplied does not match is shown.

  When any job is input, image forming apparatus 1 according to the present embodiment starts image formation based on the job according to the paper setting at that time. In this image formation, for example, the image forming conditions such as the density of the toner image, the sheet conveyance speed, and the bias voltage are appropriately adjusted according to the sheet setting. That is, the image processing unit 2 forms a toner image in accordance with image forming conditions according to the paper settings. For this reason, when a sheet S of a sheet type different from the image forming condition is supplied from the sheet holding unit 20, there is a possibility that problems such as a jam, an image defect, and a fixing defect occur.

  As shown in FIGS. 2A and 2B, the image forming apparatus 1 determines whether or not the sheet type of the sheet S that is actually supplied matches a preset sheet setting. Instead, the toner image forming process is started. Then, before the formed toner image is transferred to the paper S, it is determined whether or not the paper type of the actually supplied paper S is compatible with the current paper setting.

  In the present specification, “the paper type conforms to the paper setting” means that the paper type of the detected paper S matches the paper type selected in the paper setting, This includes the case where the paper type does not match, but printing on the target paper S can be performed appropriately according to the image forming conditions selected according to the paper settings. In other words, the detected paper type and the paper type selected as the paper setting do not match, but if the same image forming conditions can be used, they are considered to be compatible.

  As shown in FIG. 2A, when the paper type of the actually supplied paper S conforms to the current paper setting, the toner image is directly applied to the paper S as in the normal image forming process. At the same time, the toner image is fixed and discharged onto the discharge tray 34.

  More specifically, as shown in FIG. 2A, when a job 1 is input at time t1, the image processing unit 2 follows the input job 1 based on the paper setting at that time. Toner image formation is started (image formation 1). At time t2 during the toner image formation or after the toner image formation, the conveyance of the sheet S from the sheet holding unit 20 is started. When the sheet S arrives at a predetermined position at time t3, the sheet type of the arrived sheet S is detected, and it is determined whether or not the detected sheet type is compatible with the current sheet setting. If the two match, the transfer of the toner image onto the paper S is started. After completion of the transfer, at time t4, the fixing process of the toner image is started in the fixing device 30, and the discharge of the paper S on which the toner image is fixed is completed at time t5.

  Note that, during the fixing process or the discharging process (time t6), the next job 2 may be received and toner image formation may be started in accordance with the job 2.

  On the other hand, as shown in FIG. 2B, when the paper type of the actually supplied paper S conforms to the current paper setting, the paper setting is changed according to the actually supplied paper S. At the same time, the toner image is formed again according to the changed paper setting. The re-formed toner image is transferred to the paper S, and the toner image is fixed on the paper S, and then the paper S is discharged onto the discharge tray 34.

  More specifically, as shown in FIG. 2B, when job 1 is input at time t1, the image processing unit 2 follows the input job 1 based on the paper setting at that time. Toner image formation is started (image formation 1). At time t2 during the toner image formation or after the toner image formation, the conveyance of the sheet S from the sheet holding unit 20 is started. When the paper S arrives at a predetermined position at time t3, the paper type of the arrived paper is detected, and it is determined whether or not the detected paper type is compatible with the current paper setting. If the two do not match, the previously formed toner image is cleaned from the image carrier (in the configuration shown in FIG. 1, the intermediate transfer belt 16), and then based on the detected paper type, A toner image according to job 1 is formed again (image formation 1 ′). The conveyance of the paper S is in a standby state until the toner image is completely re-formed and transferred onto the paper S.

  Thereafter, when the re-formed toner image can be transferred at time t3 ', transfer of the toner image to the paper S is started. After completion of the transfer, at time t4 ', the fixing process of the toner image is started in the fixing device 30, and the discharge of the sheet S on which the toner image is fixed is completed at time t5'.

  Note that the next job 2 may be received during the fixing process or the discharge process (time t <b> 6 ′), and toner image formation may be started in accordance with the job 2.

  The image forming apparatus 1 according to the present embodiment determines whether or not the advance paper setting and the actual paper type of the paper S are compatible, and then transfers the toner image formed according to the advance paper setting. In addition, by adopting the fixing process, it is possible to avoid jamming, image defects, and fixing defects caused by the mismatch between the paper characteristics and the image forming process. At the same time, as long as the advance paper setting and the actual paper type of the paper S are compatible, the image formation does not have a function for confirming the compatibility between the paper setting and the paper type of the paper S as described above. Similar to process, throughput and FCOT can be achieved.

  That is, if the pre-paper setting and the actual paper type of the paper S are compatible, the FCOT is a time between the times t1 to t5 shown in FIG. 2A, and if not, the FCOT is This is the time between times t1 and t5 ′ shown in FIG.

  As described above, the control unit 100 of the image forming apparatus 1 causes the image processing unit 2 to form a toner image in accordance with the image forming conditions corresponding to the current paper setting, and the transport mechanism (the pair of paper feed rollers 24 and the pair of papers). The timing roller 26 and the like) start supplying the paper S. Then, the control unit 100 of the image forming apparatus 1 determines whether or not the paper type of the supplied paper S matches the current paper setting based on the detection result from the paper type detection sensor. If the paper type of the paper S matches the current paper setting, the transfer of the formed toner image to the supplied paper S is continued. On the other hand, the control unit 100 of the image forming apparatus 1 forms an image corresponding to the paper type of the paper S supplied to the image processing unit 2 when the paper type of the supplied paper S does not match the current paper setting. After the toner image is re-formed according to the conditions, the re-formed toner image is transferred to the supplied paper S.

[C. Main part configuration]
Next, a configuration of main parts for realizing the image forming process according to the present embodiment will be described. FIG. 3 is a schematic cross-sectional view showing the main configuration of image forming apparatus 1 according to the present embodiment. Referring to FIG. 3, along the conveyance path 28 from the sheet holding unit 20 to the secondary transfer roller 18, from the upstream side, the paper feed roller 24, the paper type detection sensor (the printing surface side sensor 40 and the non-printing surface side). The sensor 42) and the timing roller 26 are arranged in that order. Between the paper feed roller 24 and the paper type detection sensor, a manual paper feed roller 36 and its transport path 28 for supplying the paper S placed on the manual feed tray are provided.

  The sheet holding unit 20 may be configured by one or a plurality of paper feed cassettes 22. In such a case, a paper feed roller 24 is provided in each paper feed cassette 22. That is, the paper S may be supplied from a paper feed roller disposed in association with a paper feed cassette 22 (not shown in FIG. 3).

  The paper type detection sensor is disposed at a stage before the toner image formed by the image processing unit 2 is transferred to the paper S. More specifically, the paper type detection sensor is disposed on the upstream side of the timing roller 26 disposed on the transport path 28. As an example, the paper type detection sensor includes a pair of printing surface side sensors 40 and a non-printing surface side sensor 42 arranged so as to sandwich the paper S. Based on the detection result from the paper type detection sensor, the paper type of the supplied paper S is detected.

  The timing roller 26 is a mechanism for controlling the supply timing of the paper S to the secondary transfer roller 18. As described above, when the toner image is re-formed, the timing roller 26 removes the paper S. By waiting in the sandwiched state and rotating the timing roller 26 according to the timing at which the re-formation of the toner image is completed, the sheet S is supplied to the secondary transfer roller 18 at an appropriate timing.

  In image forming apparatus 1 according to the present embodiment, a paper type detection sensor is arranged on the upstream side of timing roller 26, and image process unit 2 (see FIG. 1) and timing roller 26 according to the detected paper type. By controlling the processing and operation, the image forming process according to the present embodiment is realized.

  As described above, in the present embodiment, the transport mechanism includes the timing roller 26 that supplies the paper S to the image processing unit 2. The paper type detection sensor is disposed upstream of the timing roller 26. The control unit 100 of the image forming apparatus 1 re-forms the toner image in a state where the sheet S is stopped upstream of the timing roller 26.

[D. Paper type detection sensor]
Next, the paper type detection sensor (see FIG. 3) will be described. Any method can be employed as the paper type detection sensor. As an example of a method for detecting the paper type, the paper thickness of the paper S can be measured, and the paper type can be determined based on the measured paper thickness.

  Thus, a sensor for detecting the paper thickness may be employed as the paper type detection sensor. By adopting a sensor for detecting the paper thickness as the paper type detection sensor, the paper type can be easily detected from the paper thickness of the paper S.

  As a method for measuring the sheet thickness of the sheet S, for example, a non-contact type sensor and a contact type sensor can be used.

  As the non-contact sensor, for example, an optical sensor using a laser light source or the like can be used. Specifically, it is arranged on one side of the arrived paper S, irradiated with laser light from the light projecting unit, and the intensity of light detected by the light receiving unit arranged on the opposite side (translucency) The sheet thickness of the sheet S can be measured based on the amount or transmissivity.

  Alternatively, distance sensors using laser light or the like are arranged on both sides of the paper S, and the paper of the paper S is based on the difference between the total distance measured by each distance sensor and the arrangement interval between the distance sensors. Thickness can be measured.

  As described above, the sheet thickness of the sheet S can be measured in a non-contact manner using a laser beam or the like.

  FIG. 3 shows a configuration example of a contact sensor as an example. Specifically, the printing surface side sensor 40 and the non-printing surface side sensor 42 are opposed to each other on both sides of the conveyance path 28. The printing surface side sensor 40 and the non-printing surface side sensor 42 are displacement sensors that are disposed so as to sandwich the paper and that are displaced in a direction across the conveyance path 28. At least one of the printing surface side sensor 40 and the non-printing surface side sensor 42 is provided with an actuator for giving displacement in a direction crossing the conveyance path 28. The printing surface side sensor 40 with the paper S interposed therebetween. The sheet thickness is measured based on the displacement generated in the non-printing surface side sensor 42. The sheet thickness is measured on the basis of the amount of displacement generated in both sensors in the state of being in contact with the sheet S using the actuator of the printing surface side sensor 40 and / or the actuator of the non-printing surface side sensor 42.

  As described above, in the image forming apparatus, as the paper thickness detection sensor, the sensors are arranged on the printing surface side and the non-printing surface side of the paper S, and the sensors connected to the sensors on both sides can contact each other. In this state, it is arranged on the transport path 28. That is, the sensor for detecting the paper thickness is composed of a pair of sensors disposed on the printing surface side and the non-printing surface side of the paper, and the pair of sensors are disposed on the conveyance path so as to sandwich the paper by the actuator. The By adopting such a configuration, the sheet thickness can be accurately measured regardless of the posture of the sheet S.

[E. Control structure]
Next, an example of a control structure for realizing the image forming process according to the present embodiment will be described. FIG. 4 is a schematic diagram showing an example of a control structure in image forming apparatus 1 according to the present embodiment. The control structure shown in FIG. 4 is typically provided by the control unit 100 (see FIG. 1) of the image forming apparatus 1. More specifically, when the control unit 100 includes a processor, the control unit 100 may be realized by executing a control program, or the control unit 100 includes a hard wired circuit such as an ASIC. 4 may be mounted on the ASIC. The circuit configuration for realizing the function shown in FIG. The control structure shown in FIG. 4 may be realized in cooperation with not only the control unit 100 but also the image forming unit 120 (see FIG. 1), an external device, or the like. The implementation form of the control structure in the present invention is not limited to a specific hardware configuration.

  Referring to FIG. 4, control unit 100 includes a paper setting management unit 102, a paper type detection unit 104, and a process control unit 106 as components of the control structure.

  The paper setting management unit 102 provides management functions such as registration, update, and deletion of the paper setting 103. Specifically, the paper setting management unit 102 receives a user operation via the input unit 110 (see FIG. 1), and registers, updates, and deletes the paper setting 103 in accordance with the user operation. The paper setting management unit 102 refers to the stored paper setting 103 and outputs the content of the paper setting to the process control unit 106.

  The paper type detection unit 104 determines the paper type of the target paper S based on the paper thickness measured by the paper type detection sensor (see FIG. 3). Specifically, the paper type detection unit 104 has a paper type information table 105 in which the paper thickness and the paper type are associated with each other. The paper type detection unit 104 detects the paper thickness from the paper type detection sensor. Based on the measurement result, the paper type is determined with reference to the paper type information table 105. The paper type detection unit 104 outputs the detected paper type to the process control unit 106.

  The process control unit 106 outputs a necessary command to the image forming unit 120 (see FIG. 1) according to the input job. More specifically, the process control unit 106 uses a bitmap command for drawing a toner image so that a toner image corresponding to the target paper S is formed based on the paper setting and / or paper type. , A transport command for transporting the paper S, a bias command for setting various biases (charging bias, transfer bias, etc.), and the like are output.

  The process control unit 106 holds a process setting table 107, and by referring to the process setting table 107 based on the paper setting and / or the paper type for an input job, a setting suitable for the job. Determine the value.

  As described above, the process control unit 106 instructs the image forming unit 120 to re-form a toner image or the like when the detected paper type does not match the current paper setting.

[F. Changing the paper settings by the user]
In the image forming process according to the present embodiment, when the paper type of the paper S that is actually supplied does not match the preset paper setting, the paper setting is performed according to the detected paper type. Thus, the toner image may be automatically re-formed. Alternatively, instead of automatically redoing image formation, the user may be prompted to reset.

  FIG. 5 is a diagram showing an example of a user interface screen that prompts the user to change the sheet setting in the image forming apparatus 1 according to the present embodiment. FIG. 5 shows an example of a user interface screen provided when the pre-paper setting and the paper type of the paper S actually supplied do not match.

  The user interface screen 200 shown in FIG. 5A notifies that the current paper setting does not match the paper type of the actually provided paper S, and prompts the user to change the paper setting. Message 202 is presented. On the user interface screen 200, the user selects a paper setting corresponding to the paper type of the paper S loaded in the paper feed cassette 22 from the icons 204.

  In this way, by supplying the paper S of a paper type different from the paper setting selected in advance, the paper S is stopped on the upstream side of the timing roller 26, and the user is notified of the paper. A user interface screen 200 is provided that prompts the user to make settings again. That is, when the paper type of the supplied paper S and the current paper setting do not match, the control unit 100 of the image forming apparatus 1 prompts the user with the paper S stopped upstream from the timing roller 26. In response, the user is prompted to change the paper setting. By providing such a user interface screen 200 to the user, the user can be made aware that the paper setting is incorrect.

  The user interface screen 210 shown in FIG. 5B notifies that the current paper setting does not match the paper type of the actually provided paper S, and prompts the user to change the paper setting. Message 212 is presented. Further, on the user interface screen 210, in addition to the icon 214 indicating the current paper setting, an icon group 216 indicating each paper setting that is a candidate after the change is displayed.

  Of the icons included in the icon group 216, the paper setting icon 218 that is preferably selected is presented in a different display mode according to the detection result of the actually supplied paper S. As a different display mode, the color scheme, presence / absence of blinking, or the like may be different, or some additional message may be displayed.

  As described above, in the present embodiment, the paper type of the paper S that is actually supplied differs from the paper setting that is actually supplied, and the paper S is detected when the user is prompted to reset the paper setting. The user may recommend paper settings corresponding to the selected paper type. That is, the control unit 100 of the image forming apparatus 1 recommends a change to the paper setting corresponding to the paper type of the supplied paper S. In this way, if it is necessary to reset the paper settings because the paper settings are incorrect in advance, the detected paper type is recommended to the user so that the paper settings can be made for the next and subsequent times. , It is possible to prevent the user from setting the paper by mistake.

[G. Switch process speed]
In the image forming process according to the present embodiment, the toner image may be re-formed. In such a case, the process speed may be switched suitable for re-forming the toner image.

  FIG. 6 is a time chart for explaining the behavior of the main part in the image forming process according to the present embodiment. FIG. 6 shows an example of a time chart in the case where the advance paper setting and the paper type of the paper S actually supplied do not match.

  Referring to FIG. 6, when job 1 is input at time t1, image processing unit 2 starts to form a toner image according to the input job 1 based on the paper setting at that time (image). Formation 1). At time t2 during the toner image formation or after the toner image formation, the conveyance of the sheet S from the sheet holding unit 20 is started. When the sheet S arrives at the detection range of the sheet type detection sensor at time t3, the sheet type of the arrived sheet is detected, and it is determined whether or not the detected sheet type matches the current sheet setting. . In the example shown in FIG. 6, since the two are not compatible, the toner image formed earlier is cleaned from the image carrier (in the configuration shown in FIG. 1, the intermediate transfer belt 16) and then detected. A toner image according to job 1 is formed again on the basis of the sheet type (image formation 1 ′). The conveyance of the paper S is in a standby state until the toner image is completely re-formed and transferred onto the paper S.

  In the process of cleaning the toner image from the image carrier, the process speed may be increased in order to complete the cleaning in a short time. The process speed is a speed related to image formation in the image processing section 2, and typically corresponds to a rotational speed of the intermediate transfer belt 16 that is an image carrier.

  For example, if it is determined at time t3 that the paper type of the supplied paper S does not conform to the paper setting, the process speed of the image processing unit 2 is the process speed set to the selectable paper type. Of these, the maximum value may be adopted. As described above, in the image forming apparatus 1, when it is determined that the sheet setting and the sheet type do not match for the first sheet of the job, the process speed is set for each sheet type. You may switch to the fastest speed. That is, when the paper type of the supplied paper S does not match the current paper setting, the process speed in the image processing unit 2 is switched to the highest process speed among the process speeds set for each paper type. Also good. By adopting such a configuration, it is possible to quickly clean the toner image on the intermediate transfer belt 16 that is an image carrier, and to shorten the return time to the image formation again.

  After increasing the process speed as described above, the process speed may be returned to the original process speed or switched to the process speed corresponding to the detected paper type under the following conditions or timing.

  For example, when it is determined that the detected paper type does not match the current paper setting, the time t4 after the toner image formed on the intermediate transfer belt 16 passes through the secondary transfer roller 18 is reached. The process speed may be switched to a process speed corresponding to the detected paper type. That is, in the configuration in which the image processing unit 2 includes the intermediate transfer belt 16 and the secondary transfer roller 18 that carry the image to be formed, the control unit 100 of the image forming apparatus 1 controls the paper type of the supplied paper S. And the current paper setting do not match, after the toner image previously formed on the intermediate transfer belt 16 passes through the secondary transfer roller 18, the process speed is determined according to the paper type of the paper S supplied. You may make it switch to speed. Such a process speed switching procedure is suitable for a configuration in which the secondary transfer roller 18 can be pressed and separated.

  By adopting such a configuration, it is possible to quickly clean the toner image on the intermediate transfer belt 16 that is an image carrier, and to shorten the return time to the image formation again.

  Alternatively, if it is determined that the detected paper type does not match the current paper setting, the detected paper type is detected at time t4 after a predetermined cleaning time necessary for cleaning the secondary transfer roller 18 has elapsed. You may make it switch to the process speed corresponding to a paper type. That is, when the secondary transfer roller 18 cannot be separated, a part of the toner image on the intermediate transfer belt 16 is transferred to the secondary transfer roller 18, so that it takes time to clean it. Such a process speed switching procedure is suitable for a configuration in which the secondary transfer roller 18 cannot be pressed and separated. That is, in the configuration in which the image processing unit 2 includes the secondary transfer roller 18, the control unit 100 of the image forming apparatus 1 performs the second process when the paper type of the supplied paper S and the current paper setting do not match. After a predetermined time required for cleaning the next transfer roller 18, the process speed may be switched to a speed corresponding to the paper type of the supplied paper S.

  By adopting such a configuration, it is possible to quickly clean the toner image on the intermediate transfer belt 16 that is an image carrier, and to shorten the return time to the image formation again. Further, by rotating and driving the intermediate transfer belt 16 in the original process, it is possible to prevent image defects caused by the primary transfer rollers 15Y, 15M, 15C, and 15K of the image forming units 10Y, 10M, 10C, and 10K.

  Further, in the case of adopting a configuration in which the secondary transfer roller 18 can be pressed and separated, if it is determined that the detected paper type does not match the current paper setting, the secondary transfer roller 18 is separated. You may make it do. For example, if it is determined that the paper type of the supplied paper S does not match the paper settings at time t3, the secondary transfer roller 18 is changed to the separated state. Thereafter, at time t5, the secondary transfer roller 18 is returned to the original pressure contact state. That is, the control unit 100 of the image forming apparatus 1 may separate the secondary transfer roller 18 when the paper type of the supplied paper S does not match the current paper setting. Note that the secondary transfer roller 18 is returned to the pressure contact state after the toner image formed on the intermediate transfer belt 16 passes through the secondary transfer roller 18 or after a predetermined cleaning time has elapsed, not at time t5. You may do it.

  By adopting such a configuration, it is possible to prevent the secondary transfer roller 18 from being soiled by the toner image formed on the intermediate transfer belt 16 that is an image carrier.

  Thereafter, when transfer of the re-formed toner image becomes possible at time t5, transfer of the toner image onto the paper S is started at time t6. After completion of the transfer, at time t7, the fixing process of the toner image is started in the fixing device 30, and the discharge of the sheet S on which the toner image is fixed is completed at time t8.

  In the time chart shown in FIG. 6, as soon as it is determined that the detected paper type does not match the current paper setting, the process speed is increased and / or the secondary transfer roller 18 is separated. In this example, if the discharge of the previously processed paper S is not completed, the process speed is increased and / or the secondary transfer roller 18 is separated after the discharge is completed. May be. In FIG. 6, the process speed is increased and / or the separation of the secondary transfer roller 18 is started at time t2. This start timing is changed to the discharge completion timing of the paper S processed in advance. May be. That is, when the paper type of the supplied paper S and the current paper setting do not match, the control unit 100 of the image forming apparatus 1 processes the paper S that has been processed first. The processing speed in the image processing unit 2 may be switched after the processing for the current sheet is completed.

  As described above, after the image forming process for the paper S processed before the paper S for which the paper type is determined not to match the current paper setting is completed, the process speed is switched or the secondary The transfer roller 18 may be separated. By adopting such a configuration, it is possible to prevent the printing on the correctly set paper processed in advance from being affected.

[H. Processing procedure]
Next, a processing procedure related to the image forming process according to the present embodiment as described above will be described. FIG. 7 is a flowchart showing a processing procedure related to the image forming process according to the present embodiment. When the control unit 100 includes a processor, the steps shown in FIG. 7 are realized by the processor executing a control program.

  Referring to FIG. 7, when image forming apparatus 1 receives a job for instructing printing (step S100), it performs exposure processing and development processing according to the received job based on the current paper setting, and generates a toner image. Form (step S102). Subsequently, the image forming apparatus 1 starts a paper feeding operation for the paper S (step S104).

  When the supplied paper S reaches the detection range of the paper type detection sensor, the image forming apparatus 1 detects the paper type of the supplied paper S based on the detection result from the paper type detection sensor (step S106). . Then, the image forming apparatus 1 determines whether or not the current sheet setting matches the detected sheet type of the sheet S (step S108).

  If the current paper setting and the detected paper type of the paper S match (YES in step S108), the image forming apparatus 1 forms toner on the supplied paper S. An image transfer process, a fixing process of the transferred toner image, and a discharging process of the paper S after the toner image is fixed are performed (step S112). Then, the image forming apparatus 1 determines whether or not the next printing is necessary for the received job (step S140).

  When the next printing is necessary for the received job (YES in step S140), the processes in and after step S102 are repeated. On the other hand, if the next printing is not necessary for the received job (NO in step S140), the process ends.

  If the current paper setting and the detected paper type of the paper S do not match (NO in step S108), the image forming apparatus 1 determines the current paper type of the detected paper S for the current paper type. It is determined whether printing is possible under the image forming conditions corresponding to the paper setting (step S110). If printing is possible under the image forming conditions corresponding to the current paper setting (YES in step S110), the processing from step S112 is executed.

  In steps S108 and S110, the current paper setting is compared with the detected paper type, and if it is not wrong, the image forming process is continued, and even if it is wrong, the image forming condition is If there is no significant difference and there is no problem even if the image forming process is continued as it is, the image forming process is continued. That is, even when the paper type of the supplied paper S and the paper type included in the current paper setting do not match, the toner can be formed when image formation according to the image forming conditions according to the current paper setting is possible. The transfer of the toner image is continued without re-forming the image.

  On the other hand, if printing is not possible under the image forming conditions corresponding to the current paper setting (NO in step S110), the processing from step S114 is performed. In other words, if image formation is continued as it is, there is a possibility that problems such as jams, image defects, and fixing defects may occur. Then, the image forming process is temporarily stopped and printing is performed under image forming conditions suitable for the target paper S. To do.

  First, the image forming apparatus 1 determines whether it is the first print of the received job (step S114). If it is not the first print of the received job (NO in step S114), the formed toner image is transferred to the previously processed paper S, and the transferred toner image is fixed. Then, the discharge process of the sheet S after the toner image is fixed is continued (step S116).

  When it is the first print of the received job (in the case of YES in step S114), or after completion of the discharge processing of the paper S that has been processed first (after execution of step S116), the image forming apparatus 1 Then, the conveyance process of the target paper S and the image forming process for the paper S are stopped (step S118).

  Subsequently, the image forming apparatus 1 separates the secondary transfer roller 18 (step S120). Then, the image forming apparatus 1 notifies the user that the current paper setting does not match the paper type of the paper S that is actually provided (step S122). Further, the user may be prompted to change the paper setting.

  Subsequently, the image forming apparatus 1 switches the process speed to the highest speed (step S124), and cleans the toner image formed on the intermediate transfer belt 16 that is an image carrier (step S126). Then, the image forming apparatus 1 changes the image forming condition to that corresponding to the detected paper type of the paper S (step S128), and the toner image generated by the previous image forming process causes the secondary transfer roller 18 to move. After passing, the process speed is switched to a speed corresponding to the changed image forming condition (step S130), and the secondary transfer roller 18 is pressed against (step S132).

  Then, the image forming apparatus 1 performs exposure processing and development processing according to the received job based on the switched image forming conditions, and re-forms the toner image (step S134). Subsequently, the image forming apparatus 1 resumes the paper feeding operation of the paper S in synchronization with the re-formed toner image (step S136). And the process after step S112 is implemented.

  As described above, when it is necessary to redo image formation on the first sheet of the job, the sheet S is stopped by the timing roller 26, the process speed is switched to the highest speed, and the cleaning of the intermediate transfer belt 16 is started. To do. At this time, if there is a mechanism that presses and separates from the secondary transfer roller 18, the toner image on the intermediate transfer belt 16 is quickly passed through the secondary transfer roller 18, and the timing roller 26 is pressed against after the passage. Then redo image formation. If the secondary transfer roller 18 cannot be pressed and separated, the toner adhering to the secondary transfer roller 18 may be cleaned and image formation may be performed again.

  When it is necessary to redo the image formation for the second and subsequent jobs, the newly formed paper S is stopped at the position of the timing roller 26 and the image formation on the preceding paper with the correct setting is completed. After that, cleaning and re-formation of image formation are performed.

The image forming process according to the present embodiment can be realized by the processing procedure as described above.
[I. Automatic setting mode]
The above description relates to the process of determining whether or not the pre-paper setting and the paper type of the actually supplied paper S are compatible. In addition to such a process, the supplied paper S A mode (hereinafter also referred to as “automatic setting mode”) in which image formation is started after the paper type is detected may be implemented. Hereinafter, the automatic setting mode will be described.

  In the automatic setting mode, image formation (formation of a toner image) is started after the paper type of the paper S supplied from the sheet holding unit 20 is detected. In the automatic setting mode, the automatic setting mode for automatically setting the paper type can be selected on the paper type setting screen displayed on the touch panel provided on the front surface of the image forming apparatus 1 or the like. May be. As described above, when the automatic setting mode is selected, image formation is started after the paper type is detected.

  FIG. 8 is a time chart for explaining the automatic setting mode of image forming apparatus 1 according to the present embodiment. Referring to FIG. 8, when the automatic setting mode is selected, when job 1 is input at time t <b> 1, conveyance of sheet S is started from sheet holding unit 20. When the sheet S arrives at a predetermined position at time t2, the sheet type of the arrived sheet S is detected, and the sheet setting is updated according to the detected sheet type. Then, the image processing unit 2 starts toner image formation according to the input job 1 based on the updated paper setting (image formation 1). At this time, the sheet S waits while being sandwiched between the timing rollers 26.

  After the toner image is formed (time t3), the conveyance of the sheet S is resumed, and the transfer of the toner image onto the sheet S is started at time t4. After completion of the transfer, at time t5, the fixing process of the toner image is started in the fixing device 30, and the discharge of the paper S on which the toner image is fixed is completed at time t6.

  By adopting such an automatic setting mode, it is possible to start image formation after setting paper according to the paper type of the paper S actually supplied. That is, the control unit 100 of the image forming apparatus 1 detects the detection by the paper type detection sensor when the automatic setting mode for determining the image forming condition according to the detection result of the paper type of the supplied paper S is selected. After the result is obtained, formation of a toner image in the image process unit 2 is started. As described above, when the image formation is started according to the preset paper setting, or when it is found that the paper type of the actually supplied paper S does not match the paper setting, the formed toner Although it is necessary to clean the image from the image carrier, such processing is not necessary in the automatic setting mode, and it is possible to detect the paper type at an early stage and start image forming processing according to appropriate paper settings.

  When the automatic setting mode is selected, the transport speed for the paper S is the lowest transport speed set for the selectable paper type until the paper type of the first paper S is detected. A value may be adopted. That is, when the automatic setting mode is selected, the conveyance speed from the sheet holding unit 20 to the paper type detection sensor may be conveyed at the lowest conveyance speed set for each paper type. That is, the transport speed when transporting the paper S to the detection range of the paper type detection sensor may be switched to the lowest transport speed among the transport speeds set for each paper type.

  In this manner, by conveying the paper S at the lowest paper speed until the paper type of the paper S is detected, it is possible to reduce the possibility of a jam that occurs before the paper S reaches the paper type detection sensor. .

  Note that during the fixing process or the discharging process (time t7), the next job 2 may be received and toner image formation may be started in accordance with the job 2. For this job 2, image formation may be performed according to the paper setting corresponding to the paper type detected in job 1. In other words, once the paper setting is updated according to the paper type detected when the first job is processed, subsequent jobs may be sequentially processed according to the updated paper setting.

  FIG. 9 is a diagram for describing a sheet setting state in the automatic setting mode of image forming apparatus 1 according to the present embodiment. Referring to FIG. 9, it is assumed that the paper type of supplied paper S is detected after the automatic setting mode is selected, and the paper setting is updated according to the detected paper type. Subsequent input jobs are processed according to the updated paper settings. This updated paper setting may be continued until there is a possibility that the paper type of the supplied paper S is changed. As an example of the possibility that the paper type of the supplied paper S is changed, for example, detection that the paper feed cassette 22 has been removed can be considered. That is, when a new paper S is supplied from the paper feed cassette 22 and is supplied, a paper S of a paper type different from the paper type of the paper S supplied in the previous processing is supplied. In such a case, the paper setting may be reset once and a new paper type may be detected.

  As described above, in the state where the automatic setting mode is selected, the paper setting corresponding to the detected paper type is maintained after the job in which the paper type is detected until the paper cassette is detached. That is, when the automatic setting mode is selected, the control unit 100 of the image forming apparatus 1 maintains the image forming conditions corresponding to the detected paper type until the paper feeding cassette is attached or detached. The subsequent job may be processed as it is. Under the assumption that the paper type has not been changed by maintaining the paper settings according to the detected paper type from the time when the paper type is detected until the paper cassette is removed. Therefore, it is possible to form an image according to the previously determined paper setting, and the first copy time can be shortened.

  FIG. 10 is a flowchart showing a processing procedure in the automatic setting mode according to the image forming process according to the present embodiment. Each step shown in FIG. 10 is realized when the control unit 100 includes a processor, and the processor executes a control program.

  Referring to FIG. 10, the image forming apparatus 1 determines whether or not the automatic setting mode is selected (step S200). If the automatic setting mode is not selected (NO in step S200), the processing in step S100 and subsequent steps in the flowchart shown in FIG. 7 is executed.

  If the automatic setting mode has been selected (YES in step S200), the image forming apparatus 1 starts the sheet S feeding operation (step S202). When the supplied paper S reaches the detection range of the paper type detection sensor, the image forming apparatus 1 detects the paper type of the supplied paper S based on the detection result from the paper type detection sensor (step S204). . Then, the image forming apparatus 1 changes the image forming condition to that according to the detected paper type of the paper S (step S206).

  The image forming apparatus 1 stops the conveyance process of the target paper S (step S208), and performs the exposure process and the development process according to the received job based on the image forming condition after the switching to re-form the toner image. (Step S210). Subsequently, the image forming apparatus 1 resumes the paper feeding operation of the paper S in synchronization with the formed toner image (step S212). The image forming apparatus 1 performs transfer processing of the formed toner image, fixing processing of the transferred toner image, and discharging processing of the paper S after the toner image is fixed on the supplied paper S ( Step S214).

  Then, the image forming apparatus 1 determines whether or not the next printing is necessary for the received job (step S216). If the next print is not necessary for the received job (NO in step S216), the process ends.

  On the other hand, when the next printing is necessary for the received job (YES in step S216), the image forming apparatus 1 determines whether or not the paper feed cassette 22 has been removed (step S218). The previously determined image forming conditions are maintained until the paper feed cassette 22 is newly detached. That is, if the paper feed cassette 22 has been removed (YES in step S218), the operations in step S202 and subsequent steps are repeated. On the other hand, if the paper feed cassette 22 has not been detached (NO in step S218), the image forming apparatus 1 performs the processing in step S102 and subsequent steps shown in FIG. Furthermore, the process after step S216 is implemented.

  As described above, when the automatic setting mode is provided and the automatic setting mode is selected, paper feeding may be started at the lowest speed before the image forming process. Then, after detecting the sheet type on the upstream side of the timing roller 26, the sheet S is stopped at the position of the timing roller 26, and image formation is started under the correct image forming conditions, and the sheet S and the toner image are detected. The conveyance is started again at the timing when the positions match, and the transfer process, the fixing process, and the discharge process are performed. In the automatic setting mode, once the paper type is detected, the paper in the same paper cassette is estimated to be the same type, and the paper type detected is automatically set until the paper cassette is opened and closed. You may perform the same process as usual when the mode is not selected.

  Note that even in a configuration in which the automatic setting mode is not implemented, image formation may be performed again when the set paper setting does not match the detected paper type.

[J. Monitoring compatibility between paper type and paper settings]
In image forming apparatus 1 according to the present embodiment, compatibility between the paper type of paper S that is actually supplied and the paper settings is determined. The determination of compatibility between the paper type and the paper setting may be performed when each job is executed regardless of whether or not the automatic setting mode as described above is selected.

  That is, if the automatic setting mode is not selected, the suitability is determined when each job is processed. If the automatic setting mode is selected, the first job for paper setting is processed. The suitability may be determined when each subsequent job processed later is processed. That is, the control unit 100 of the image forming apparatus 1 determines the paper type of the supplied paper S and the current paper based on the detection result from the paper type detection sensor even when the automatic setting mode is not selected. It may be determined whether the setting matches.

  By adopting such a monitoring process, it is possible to suppress the occurrence of a jam, an image defect, and a fixing defect even when sheets S of different sheet types are loaded in the sheet feeding cassette 22.

  In image forming apparatus 1 according to the present embodiment, even when automatic setting mode is not selected, the paper type of supplied paper S is detected, and the detected paper type becomes the current paper setting. It is determined whether or not the sheet S is suitable, and when a sheet S of a sheet type that does not conform to the current sheet setting is supplied, the sheet S is stopped on the upstream side of the timing roller 26 and detected. The toner image may be formed again according to the paper setting corresponding to the paper type.

  As described above, even when the automatic setting mode is not selected, the paper type of the supplied paper S is monitored, and the paper having the image forming condition different from the set paper setting has been supplied. In this case, the sheet S is stopped on the upstream side of the timing roller 26, the paper type is reset, and the toner image is formed again, so that jamming, image defect, fixing due to mixed loading of papers or incorrect setting. Defects can be prevented.

[K. Summary]
If image formation is not performed in accordance with image formation conditions corresponding to the paper type, problems such as jams, image defects, and fixing defects may occur. For this reason, in general, when printing is performed by changing the paper type such as thick paper, the user is required to set the paper type. However, even when printing on thick paper, a jam or the like may occur because the paper type is not set. For such a problem, the image forming apparatus according to the present embodiment employs the configuration and processing as described above, so that when the paper type is set correctly, printing is performed in a short first copy time, Only when the paper type is unknown or wrong, the first copy time can be extended and printing can be performed under correct image forming conditions.

Image forming apparatus 1 according to the present embodiment has the following technical ideas.
According to the first aspect, in an image forming apparatus in which image forming conditions such as process setting, conveyance speed, and fixing setting are varied depending on the paper type, the paper type is detected by a paper type detection sensor disposed downstream of the paper feed roller. If the image forming conditions differ from the selected paper type, the paper is passed. If the image cannot be guaranteed, the paper is temporarily stopped, the paper type is set again, and the image is formed again. The paper type detection sensor located downstream of the paper feed roller detects the paper type and passes the paper unless the image formation conditions differ from the selected paper type. By temporarily stopping, re-setting the paper type, and redoing image formation, it is possible to prevent jamming, image defects, and fixing defects caused by printing on paper with inappropriate settings. Since the resetting is performed automatically, there is no inconvenience that the user performs image formation again after viewing the printed paper, and inconvenience of having the user resetting can be prevented.

  According to the second aspect, in the image forming apparatus, the paper type detection sensor is arranged on the upstream side of the timing roller, and upstream of the position of the timing roller when the image forming conditions are different paper types. Then, image re-formation may be started with the sheet stopped. If the paper type detection sensor is located upstream of the timing roller and the image formation conditions are different, the image is re-formed with the paper stopped upstream of the timing roller position. By starting, it is possible to prevent the position of the leading end of the image from shifting.

  According to the third aspect, in the image forming apparatus, in the image forming apparatus, when the paper type detected by the paper type detection sensor and the selected paper type can be printed under the same image forming conditions, as set. Printing may be continued with the image forming conditions. If the paper type detected by the paper type detection sensor and the selected paper type can be printed under the same image forming conditions, there is no problem in printing by continuing printing with the image forming conditions as set. It is possible to print on paper after confirming the above.

  According to the fourth aspect, in the image forming apparatus, an automatic setting mode for automatically setting the paper type is provided on the paper type setting screen. When the automatic setting mode is selected, image formation is performed after the paper type is detected. You may make it start. An automatic setting mode that automatically sets the paper type is provided on the paper type setting screen. When the automatic setting mode is selected, the toner on the intermediate transfer belt is cleaned by starting image formation after detecting the paper type. Therefore, it is possible to quickly detect the paper type and shift to image formation.

  According to the fifth aspect, in the image forming apparatus, a mode for automatically setting the sheet type is provided on the sheet type setting screen, and when the automatic setting mode is selected, the sheet conveyance speed to the sheet type sensor is set to each sheet. It may be conveyed at the lowest speed of the seed. When the automatic setting mode is selected, jamming until reaching the paper type detection sensor can be prevented by conveying the paper conveyance speed to the paper type detection sensor at the minimum speed of each paper type.

  According to the sixth aspect, in the image forming apparatus, a mode for automatically setting the paper type is provided on the paper type setting screen, and after the job in which the paper type is detected in the automatic setting mode until the paper cassette is detached, You may switch to the setting of the paper type detected by the type detection sensor. In the automatic setting mode, after the job is detected, it is assumed that the paper type has not been changed by switching to the paper type setting detected by the paper type detection sensor after the paper type is detected The first sheet discharge speed of the job can be increased.

  According to the seventh aspect, in the image forming apparatus, even when the automatic setting mode is not selected, the paper type is monitored, and a paper having an image forming condition different from the selected paper type is passed. Alternatively, the sheet may be stopped on the upstream side of the timing roller, the sheet type may be automatically reset, and image formation may be performed again. Even when the automatic setting mode is not selected, the paper type is monitored, and if paper with image formation conditions different from the selected paper type is passed, the paper is stopped upstream of the timing roller. By automatically resetting the paper type and redoing image formation, it is possible to prevent mixed paper loading, jamming at the wrong setting, image defects, and fixing defects.

  According to the eighth aspect, when the image forming apparatus detects that the first sheet of the job has different image forming conditions, the process speed is switched to the highest speed of each sheet type and rotated. May be. If it is detected that the first sheet of the job has different image formation conditions, the toner on the intermediate transfer belt can be cleaned quickly by switching the process speed to the highest speed of each paper type and rotating it. The return time to re-image formation can be shortened.

  According to the ninth aspect, in the image forming apparatus capable of pressing and separating the secondary transfer roller, when the paper type detection sensor detects that the image forming conditions are different, the secondary transfer roller is separated. Also good. When the secondary transfer roller is an image forming apparatus capable of being pressed and separated, the secondary transfer roller is separated by separating the secondary transfer roller when the paper type detection sensor detects that the paper has different image forming conditions. The roller can be prevented from being soiled.

  According to the tenth aspect, in the image forming apparatus, when the paper type detection sensor detects that the paper has different image forming conditions, the toner on the intermediate transfer belt passes through the secondary transfer roller position. The process speed may be switched according to the paper type. When the secondary transfer roller is an image forming apparatus that can be pressed and separated, the toner on the intermediate transfer belt moves the position of the secondary transfer roller when the paper type detection sensor detects that the image forming conditions are different. By driving the paper sheet at the highest speed until it passes, and switching to the process speed according to the paper type after passing through the secondary transfer roller position, the return time to re-image formation can be shortened.

  According to the eleventh aspect, in the image forming apparatus in which the secondary transfer roller cannot be pressed and separated, when it is detected that the paper has different image forming conditions, the secondary transfer roller is adjusted to the paper type after the cleaning time of the secondary transfer roller has elapsed. You may switch to a different process speed. In the image forming apparatus in which the secondary transfer roller cannot be pressed and separated, when it is detected that the image forming conditions are different paper, after the cleaning time of the secondary transfer roller has elapsed, by switching to a process speed that matches the paper type, It is possible to prevent image defects from occurring on the primary transfer roller.

  According to the twelfth aspect, when the image forming apparatus detects that the second and subsequent sheets have different image forming conditions, the image forming process preceding the sheet from which the difference is detected is completed. After that, the process speed may be switched. If it is detected that the second and subsequent sheets of the job have different image forming conditions, the correct setting is made by switching the process speed after completing the image forming process prior to the sheet where the difference is detected. It is possible to prevent the printed paper from being affected.

  According to the thirteenth aspect, in the image forming apparatus, when the automatic setting mode is not selected and the sheet different from the selected sheet type is passed, the sheet is stopped on the upstream side of the timing roller. The user may be prompted to reset the paper type. If a paper different from the selected paper type is passed when the automatic setting mode is not selected, stop the paper upstream of the timing roller and prompt the user to reset the paper type. It will be possible for users to understand that they are making the wrong settings.

  According to the fourteenth aspect, when the paper type is different and the user is prompted to reset the paper type, the paper type detected by the paper type detection sensor may be recommended. When the paper type is different and prompts the user to reset the paper type, the paper type detected by the paper type detection sensor is recommended, so that an error can be prevented when selecting the paper type next time.

  According to the fifteenth aspect, in the image forming apparatus, the paper type detection sensor may be a sensor that detects the paper thickness. By using a sensor for detecting the paper thickness as the paper type detection sensor, it is possible to easily calculate and set the paper type from the paper thickness.

  According to the sixteenth aspect, in the image forming apparatus, the paper thickness detection sensors may be arranged on the printing surface side and the non-printing surface side of the paper, and the actuators connected to the sensors on both sides may be in contact with each other and arranged in the conveyance path. Paper thickness detection sensors are placed on the printing surface side and non-printing surface side of the paper, and actuators connected to the sensors on both sides are in contact with each other and placed in the transport path to accurately detect the paper thickness regardless of the paper orientation. Is possible.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 Image process part, 10C, 10K, 10M, 10Y Image forming unit, 11C, 11K, 11M, 11Y Photoconductor drum, 12C, 12K, 12M, 12Y Charger, 13C, 13K, 13M, 13Y Exposure 14C, 14K, 14M, 14Y Development unit, 15C, 15K, 15M, 15Y Primary transfer roller, 16 Intermediate transfer belt, 18 Secondary transfer roller, 20 Sheet holding unit, 22 Paper feed cassette, 24 Paper feed roller, 26 Timing roller, 28 transport path, 30 fixing device, 32 discharge roller, 34 discharge tray, 36 manual feed roller, 40 printing surface side sensor, 42 non-printing surface side sensor, 100 control unit, 102 paper setting management unit, 103 paper Setting, 104 paper type detection unit, 105 paper type information table 106, process control unit, 107 process setting table, 110 input unit, 120 image forming unit, 200, 210 user interface screen, 202, 212 message, 204, 214, 218 icon, 216 icon group, S paper.

Claims (17)

An image processing unit for forming a toner image in accordance with image forming conditions according to paper settings;
A transport mechanism for supplying paper to the image processing unit;
A paper type detection sensor disposed at a stage prior to transferring the toner image formed by the image processing unit to the paper;
A control unit for controlling the image processing unit and the transport mechanism;
The controller is
Causing the image processing unit to form a toner image in accordance with an image forming condition according to a current paper setting, and causing the transport mechanism to start supplying the paper;
Based on the detection result from the paper type detection sensor, it is determined whether the paper type of the supplied paper and the current paper setting match,
If the paper type of the supplied paper matches the current paper setting, continue the transfer of the formed toner image to the supplied paper;
When the paper type of the supplied paper and the current paper setting do not match, the image processing unit re-forms a toner image according to image forming conditions according to the paper type of the supplied paper. An image forming apparatus for transferring the re-formed toner image onto the supplied paper. The transport mechanism includes a timing roller for supplying the paper to the image processing unit,
The paper type detection sensor is disposed upstream of the timing roller,
The image forming apparatus according to claim 1, wherein the control unit re-forms the toner image in a state where the sheet is stopped upstream of the timing roller.   The control unit can form an image in accordance with the image forming condition according to the current paper setting even when the paper type of the supplied paper does not match the paper type included in the current paper setting. The image forming apparatus according to claim 1, wherein the transfer of the toner image is continued without re-forming the toner image.   When the paper type of the supplied paper and the current paper setting do not match, the control unit sets the process speed in the image processing unit as the fastest process speed among the process speeds set for each paper type. The image forming apparatus according to claim 1, wherein the image forming apparatus is switched to a speed. The image processing unit includes a belt that carries an image to be formed and a transfer roller,
The controller controls the process speed after a toner image previously formed on the belt passes through the transfer roller when a paper type of the supplied paper and the current paper setting do not match. The image forming apparatus according to claim 4, wherein the image forming apparatus is switched to a speed corresponding to a paper type of the supplied paper. The image processing unit includes a transfer roller,
When the paper type of the supplied paper does not match the current paper setting, the control unit sets the process speed to the paper of the supplied paper after a predetermined time required for cleaning the transfer roller. The image forming apparatus according to claim 4, wherein the image forming apparatus is switched to a speed corresponding to a species.   If the paper type of the supplied paper and the current paper setting do not match, and there is a paper that has already been processed, the control unit performs processing for the paper that has been processed in advance. The image forming apparatus according to claim 4, wherein a process speed in the image process unit is switched after completion. The image processing section includes a transfer roller that can be pressed and separated,
The image forming apparatus according to claim 1, wherein the control unit separates the transfer roller when a paper type of the supplied paper and the current paper setting do not match.   When the paper type of the supplied paper and the current paper setting do not match, the control unit stops the paper upstream of the timing roller and performs the paper setting to the user. The image forming apparatus according to claim 1, wherein a change is urged.   The image forming apparatus according to claim 9, wherein the control unit recommends a change to a sheet setting corresponding to a sheet type of the supplied sheet.   When the automatic setting mode for determining the image forming condition according to the detection result of the paper type of the supplied paper is selected, the control unit is configured to obtain the detection result by the paper type detection sensor. The image forming apparatus according to claim 1, wherein toner image formation in the image process unit is started.   When the automatic setting mode is selected, the control unit sets the transport speed when transporting the paper to the detection range of the paper type detection sensor to the lowest transport speed set for each paper type. The image forming apparatus according to claim 11, wherein the image forming apparatus is switched to a high conveyance speed.   When the automatic setting mode is selected, the control unit maintains subsequent image forming conditions according to the detected paper type until the paper cassette is attached or detached. The image forming apparatus according to claim 11, wherein the image forming apparatus performs processing.   The control unit matches the paper type of the supplied paper and the current paper setting based on a detection result from the paper type detection sensor even when the automatic setting mode is not selected. The image forming apparatus according to claim 11, wherein it is determined whether or not to perform.   The image forming apparatus according to claim 1, wherein the paper type detection sensor includes a sensor that detects a paper thickness.   The sensor for detecting the paper thickness includes a pair of sensors arranged on the printing surface side and the non-printing surface side of the paper, and the pair of sensors are arranged on the conveyance path so as to sandwich the paper by an actuator. The image forming apparatus according to claim 15. An image forming apparatus control method comprising:
The image forming apparatus includes: an image processing unit that forms a toner image according to an image forming condition according to a paper setting; a transport mechanism that supplies paper to the image processing unit; and a toner image formed by the image processing unit. A paper type detection sensor arranged in the previous stage of transfer to the paper,
The control method is:
Forming a toner image in accordance with an image forming condition according to a current paper setting in the image processing unit, and starting supplying the paper by the transport mechanism;
Determining whether a paper type of the supplied paper and the current paper setting match based on a detection result from the paper type detection sensor;
Continuing the transfer of the formed toner image to the supplied paper if the paper type of the supplied paper matches the current paper setting;
When the paper type of the supplied paper and the current paper setting do not match, the image processing unit re-forms a toner image according to image forming conditions according to the paper type of the supplied paper. And a step of transferring the re-formed toner image onto the supplied paper.

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