Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can easily avoid changing the type of paper used during image formation on multiple sheets of paper. [Solution] The image forming apparatus 100 comprises an image forming unit 60, paper feed trays 18a to d, and a sheet supply unit 80 that supplies sheets P to the image forming unit 60. When an image forming instruction is input to perform image forming of multiple sets of sets on which images are formed on multiple sheets P, the sheets P are supplied to the image forming unit 60 from predetermined paper feed trays 18a to d. If the sheets P in the predetermined paper feed trays 18a to d run out during the image forming process in the image forming instruction, the image forming operation is stopped. If the paper in the predetermined paper feed trays 18a to d runs out when the last sheet of paper in the predetermined set in the image forming instruction is supplied to the image forming unit 60, the paper is supplied to the image forming unit 60 from a different paper feed tray 18a to d than the predetermined paper feed trays 18a to d, and the image forming operation is continued.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus having a plurality of paper feed trays.

Background Art

[0002] In image forming apparatuses such as copiers, facsimile machines, printers, and multifunction peripherals, when a paper jam occurs, the user is notified by displaying the occurrence of the paper jam on a display unit or the like. In addition, there are image forming apparatuses that not only notify of a paper jam but also display a method of replenishing paper.

[0003] Here, among papers, even if the sizes are the same, for example, if they are from different manufacturers, even if they are the same white paper, the paper types may be different, and the paper quality may be different such as gloss and color tone. Also, there are cases where papers of different paper qualities are handled even by the same manufacturer. For example, when printing a document that is a set of multiple sheets, image formation is performed on each of the multiple sheets. However, if a paper jam occurs in the middle and the user replenishes the paper, and the replenished paper is of a different paper type from the paper immediately before the paper jam, although it is a set of the document, the paper type is changed in the middle, and there may be a problem that the user who uses the document feels discomfort.

[0004] As an image forming apparatus capable of preventing such problems, Patent Document 1 discloses an image forming apparatus that determines whether the replenished paper is different from the paper immediately before the paper jam when the user replenishes the paper after a paper jam occurs, and if it is different, displays that fact and confirms with the user whether printing can be continued as it is.

[0005] According to the image forming apparatus disclosed in Patent Document 1, if the type of paper supplied differs from the type of paper used before the paper ran out, the user is notified. The user then recognizes the difference in paper type and replenishes the paper with the same type as the paper used before the paper ran out, thus preventing the problem of the paper type changing midway through the process. Furthermore, if it is acceptable for the paper type to change midway through a single document, the user can choose to proceed with printing without replenishing the paper. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2006-142713 [Overview of the project] [Problems that the invention aims to solve]

[0007] Some image forming machines have multiple paper trays and can be configured with an automatic tray switching function that switches to another paper tray and supplies paper from that tray when the paper in the currently supplied tray runs out, allowing the image forming operation to continue continuously. In such image forming machines, if the automatic tray switching function is set, printing can be performed without stopping during a series of multiple print jobs.

[0008] However, when switching paper trays, if the paper types held in the tray before the switch and the paper types held in the tray after the switch are different, a problem will occur where the paper type changes midway through a series of print jobs.

[0009] This disclosure has been made in view of the circumstances described above, and its purpose is to provide an image forming apparatus that can easily avoid changing the type of paper used when forming images on multiple sheets of paper. [Means for solving the problem]

[0010] An image forming apparatus according to one aspect of the present disclosure is an image forming apparatus comprising: an image forming means for forming an image on paper; a plurality of paper trays, each holding a sheet of paper; and a paper supply means for drawing out sheets of paper one by one from the paper trays and supplying them to the image forming means, wherein when an image forming instruction is input to perform image forming of multiple sets of multiple sheets of paper, the paper supply means supplies paper to the image forming means from a predetermined paper tray; if the paper held in the predetermined paper tray runs out during the image forming process in the image forming instruction, the image forming means stops the image forming operation; and if the paper in the predetermined paper tray runs out when the final sheet of paper in the predetermined set in the image forming instruction is supplied to the image forming apparatus, the paper supply means supplies paper to the image forming means from a different paper tray than the predetermined paper tray, and the image forming means continues the image forming operation.

[0011] Thus, if the paper held in a designated paper tray runs out during image formation, the image formation operation stops. However, if the paper in the designated paper tray runs out after the last sheet of paper in the set is supplied to the image forming means, the image formation operation continues by supplying paper from a different paper tray to the image forming means. Therefore, even if the automatic paper tray switching function is activated and paper is supplied from another paper tray when the paper held in one tray runs out, and each paper tray holds paper of different types, the problem of different types of paper being mixed within the same set can be suppressed. Furthermore, by executing the automatic paper tray switching function, work can be performed efficiently.

[0012] Furthermore, "forming multiple sets of images" refers to, for example, forming multiple copies of a document consisting of multiple sheets of paper.

[0013] Furthermore, in the image forming apparatus described above, it is possible to set the first sheet as the cover sheet when forming an image on multiple sheets of paper, and when an image forming instruction is input to form multiple sets of images on multiple sheets of paper with the cover sheet setting, the paper supply means supplies paper to the image forming means from a predetermined paper tray. If, during the image forming process in the image forming instruction, the paper to be used as the cover sheet is supplied from the predetermined paper tray and the paper held in the predetermined paper tray runs out, the paper supply means may supply paper to the image forming means from a different paper tray than the predetermined paper tray, and the image forming means may continue the image forming operation.

[0014] This prevents the problem of different paper types being mixed within a set, regardless of the cover settings. Furthermore, the automatic paper tray switching function allows for more efficient operation.

[0015] Another image forming apparatus according to one aspect of the present disclosure is an image forming apparatus comprising: an image forming means for forming an image on paper; a plurality of paper trays, each holding a sheet of paper; and a paper supply means for drawing out sheets of paper one by one from the paper trays and supplying them to the image forming means, wherein the plurality of paper trays include a plurality of combinations of paper trays holding sheets of the same size, and different sets of paper trays hold sheets of different sizes, and when an image forming instruction is input to form multiple sets of images on a plurality of sheets of paper of different sizes, the paper supply means supplies paper from a predetermined paper tray to the image forming means according to the paper size in the image forming instruction, and if the paper held in the predetermined paper tray runs out during the image forming of a predetermined set in the image forming instruction, and if image forming on paper of the same size as the runout sheet has not been completed, the image forming means stops the image forming operation.

[0016] This prevents the problem of mixing different paper types within the same size set when paper trays of different sizes are held in multiple trays, and when the paper in one tray runs out and the automatic tray switching function is activated to supply paper from another tray, the trays may hold paper of different types. Furthermore, the automatic tray switching function allows for more efficient work.

[0017] Furthermore, in the image forming apparatus described above, if the paper held in the paper tray within the predetermined paper feed tray runs out during the image forming of a predetermined set in the image forming instruction, and image forming on paper of the same size as the runout paper has been completed, the paper supply means may supply paper to the image forming means from another paper feed tray that holds paper of the same size, different from the predetermined paper feed tray, and the image forming means may continue the image forming operation.

[0018] This means that when paper of different sizes is held in multiple paper trays, and the automatic paper tray switching function is activated to supply paper from another tray when the paper in one tray runs out, the paper quality may differ from set to set because the trays hold paper of different types. However, this prevents the problem of mixing different types of paper of the same size within the same set. Furthermore, the automatic paper tray switching function allows for more efficient work.

[0019] Furthermore, the image forming apparatus described above may be equipped with a display means, and if the image forming means stops its image forming operation during the process, the display means may display information regarding the corresponding method.

[0020] This allows users to understand how to proceed after the image formation process has stopped, enabling them to work more efficiently. [Effects of the Invention]

[0021] According to the present disclosure, it is possible to provide an image forming apparatus that can easily avoid a difference in the type of paper during image formation on a plurality of sheets of paper.

Brief Description of the Drawings

[0022] [Figure 1] It is a front view showing a schematic configuration of an image forming apparatus according to an embodiment of the present disclosure in a perspective manner. [Figure 2] It is an external view of an operation panel of an image forming apparatus according to an embodiment of the present disclosure. [Figure 3] It is a block diagram schematically showing a control configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 4] It is an external view when promoting sheet replenishment of an operation panel of an image forming apparatus according to an embodiment of the present disclosure. [Figure 5] It is a flowchart showing an example of the operation of an image forming apparatus according to an embodiment of the present disclosure. [Figure 6] It is a diagram for explaining Example 1 using an image forming apparatus according to an embodiment of the present disclosure. [Figure 7] It is a diagram for explaining Example 2 using an image forming apparatus according to an embodiment of the present disclosure. [Figure 8] It is a diagram for explaining Example 3 using an image forming apparatus according to an embodiment of the present disclosure. [Figure 9] It is a diagram for explaining Example 4 using an image forming apparatus according to an embodiment of the present disclosure. [Figure 10] It is a diagram for explaining Example 5 using an image forming apparatus according to an embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0023] Embodiments according to the present disclosure will be described with reference to the drawings.

[0024] An image forming apparatus according to an embodiment of this disclosure will be described with reference to the drawings. Figure 1 is a perspective front view showing a schematic configuration of the image forming apparatus according to an embodiment of this disclosure.

[0025] The image forming apparatus 100 is a multifunction device having copying, scanning, facsimile, and printing functions, and includes an image reading device 102 and an image forming apparatus main body 101.

[0026] The image reading device 102 includes an image reading unit 130 and a document feeder 160 [automatic document feeder (ADF)]. The document feeder 160 is located above the image reading unit 130 and is supported so as to be openable and closable relative to the image reading unit 130.

[0027] The document feeder 160 transports one or more documents G one by one in sequence. The image reader 102 reads the documents G being transported one by one by the document feeder 160.

[0028] The image reading unit 130 includes a document placement table 130a on which the document G is placed, a document reading unit 130b, and a scanning optical system 130c for reading the document.

[0029] When the document feeder 160 is opened, the document tray 130a above the image reading unit 130 is opened, allowing the document G to be placed manually. The document feeder 160 also includes a document tray 161 for placing the document G and a document output tray 162 for accumulating the documents G that have been discharged to the outside.

[0030] In the image forming apparatus 100, the document feeder 160 transports the document G placed on the document tray 161 onto the document reading unit 130b of the image reading unit 130. The image reading unit 130 generates image data by scanning the scanning optical system 130c to read the document placed on the document table 130a or by reading the document G being transported by the document feeder 160.

[0031] The image forming apparatus main body 101 includes an image transfer unit 50, an optical scanning device 1, an intermediate transfer belt device 70, a secondary transfer device 11, a fixing device 12, a sheet transport path S, paper feed trays 18a to 18d, and a sheet discharge tray 141. In particular, the image transfer unit 50, the optical scanning device 1, the intermediate transfer belt device 70, the secondary transfer device 11, and the fixing device 12 constitute the image forming unit 60. The image forming unit 60 forms an image on the surface of the sheet P using toner.

[0032] The image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (for example, black).

[0033] The image transfer unit 50 of the image forming apparatus 100 has four image stations Pa, Pb, Pc, and Pd, corresponding to black, cyan, magenta, and yellow. Each of these image stations Pa, Pb, Pc, and Pd is equipped with a developer 2, a photoreceptor drum 3, a drum cleaning device 4, and a charger 5, and these image stations Pa, Pb, Pc, and Pd form four types of toner images. In other words, in the image forming apparatus 100, there are four of each of the developer 2, photoreceptor drum 3, drum cleaning device 4, and charger 5, each corresponding to black, cyan, magenta, and yellow.

[0034] The optical scanning device 1 exposes the surface of the photoreceptor drum 3 to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photoreceptor drum 3 to form a toner image on the surface of the photoreceptor drum 3. The drum cleaning device 4 removes and recovers residual toner from the surface of the photoreceptor drum 3. The charger 5 uniformly charges the surface of the photoreceptor drum 3 to a predetermined potential. Through the above series of operations, toner images of each color are formed on the surface of each photoreceptor drum 3.

[0035] The intermediate transfer belt device 70 comprises an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. The intermediate transfer belt 71 is an endless belt that can move around and is wrapped around the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. In other words, the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73 tension the intermediate transfer belt 71. There are four intermediate transfer rollers 6, each positioned inside the intermediate transfer belt 71 to form four different toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photoreceptor drum 3 to the intermediate transfer belt 71.

[0036] The image forming apparatus 100 sequentially transfers and superimposes the toner images of each color formed on the surface of each photoreceptor drum 3 to form a color toner image on the surface of the intermediate transfer belt 71 stretched over the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. The cleaning apparatus 9 removes and collects waste toner that remains on the surface of the intermediate transfer belt 71 without being transferred to the sheet P. Specifically, after the toner image formed on the intermediate transfer belt 71 has been transferred to the sheet P, the cleaning apparatus 9 performs a cleaning operation to remove any deposits adhering to the intermediate transfer belt 71.

[0037] The secondary transfer device 11 forms a transfer nip region TN between the secondary transfer roller 11a and the intermediate transfer belt 71, and transports the sheet P that has been transported through the sheet transport path S by sandwiching it in the transfer nip region TN. The secondary transfer roller 11a is positioned opposite the intermediate transfer drive roller 72, with the intermediate transfer belt 71 sandwiched between it and the intermediate transfer drive roller 72. As the sheet P passes through the transfer nip region TN, the toner image on the surface of the intermediate transfer belt 71 is transferred to the sheet P and it is transported to the fixing device 12. Although details are omitted, when transferring the toner image from the intermediate transfer belt 71 to the sheet P, the intermediate transfer drive roller 72 and the secondary transfer roller 11a are grounded or electrically biased to facilitate the movement of negatively charged toner from the intermediate transfer belt 71 to the sheet P.

[0038] The fixing device 12 includes a fixing roller 31 and a pressure roller 32 that rotate with the sheet P in between. The fixing device 12 heats and pressurizes the sheet P, on which the toner image has been transferred, by sandwiching it between the fixing roller 31 and the pressure roller 32, thereby fixing the toner image to the sheet P. Specifically, a heater, which is a heat source, is placed inside the fixing roller 31, and the heat generated by this heater heats the surface of the fixing roller 31 that comes into contact with the sheet P on which the toner image has been transferred.

[0039] In this way, an image is formed on the sheet P by the image forming unit 60, which is equipped with an image transfer unit 50, an optical scanning device 1, an intermediate transfer belt device 70, a secondary transfer device 11, and a fixing device 12.

[0040] The four paper feed trays 18a to 18c are trays for holding sheets P used for image formation and are located on the underside of the optical scanning device 1. Each of the paper feed trays 18a to 18c is equipped with a sheet sensor 19a to 19d that detects whether or not a sheet P is held in the paper feed tray 18a to 18c. If there are no more sheets P held in each of the paper feed trays 18a to 18c, a signal is sent from the sheet sensors 19a to 19d to the control unit 180 (see Figure 3), which will be described later. Alternatively, a signal may be sent only when a sheet P is held.

[0041] Furthermore, each of the paper feed trays 18a to 18c is equipped with pickup rollers 16a to 16d for pulling out the sheets P. The sheets P held in each of the paper feed trays 18a to 18d are pulled out by the pickup rollers 16a to 16d and transported to the sheet transport path S. The sheets P transported to the sheet transport path S are transported via the secondary transfer device 11 and the fixing device 12 to the discharge roller 17 and then discharged to the sheet discharge tray 141 in the discharge section 140.

[0042] Here, each of the paper feed trays 18a to 18d may hold sheets P of different sizes, as described above, or may hold sheets P of the same size. In this embodiment, A4-sized sheets P are held in paper feed trays 18a and 18b, and A3-sized sheets P are held in paper feed trays 18c and 18d. However, the sheets P held in paper feed trays 18a and 18b are the same size but have different paper qualities, and the sheets P held in paper feed trays 18c and 18d are also the same size but have different paper qualities. Because of the different paper qualities, even if they are the same white color, the gloss and hue will differ. In addition, the size of the sheets P held in each of the paper feed trays 18a to 18d is registered and stored in the storage unit 182 described later.

[0043] The sheet transport path S is equipped with a transport roller 13, a registration roller 14, and a discharge roller 17. The transport roller 13 facilitates the transport of the sheet P. The registration roller 14 temporarily stops the sheet P and aligns its leading edge. Furthermore, the registration roller 14 transports the temporarily stopped sheet P in accordance with the timing of the color toner image on the intermediate transfer belt 71. As described above, the color toner image on the intermediate transfer belt 71 is transferred to the sheet P in the transfer nip region TN between the intermediate transfer belt 71 and the secondary transfer roller 11a.

[0044] Furthermore, if the image forming apparatus 100 is to perform image formation not only on the front surface but also on the back surface of the sheet P, it transports the sheet P in the reverse direction from the discharge roller 17 to the sheet reversal path Sr. The image forming apparatus 100 reverses the front and back surfaces of the sheet P that has been transported in the reverse direction and guides it back to the register roller 14. The image forming apparatus 100 then forms an image on the back surface of the sheet P guided to the register roller 14 in the same way as the front surface, and transports it to the sheet discharge tray 141.

[0045] Here, the pickup rollers 16a to 16d, the transport roller 13, and the registration roller 14 constitute a sheet supply unit 80 that transports the sheet P from the paper trays 18a to 18d to the image forming unit 60.

[0046] Furthermore, the image forming apparatus 100 has an automatic paper feed tray switching function. Specifically, it has a so-called auto tray switch function, which, if any of the paper feed trays 18a to 18d that supply sheets P to the image forming unit 60 run out, supplies sheets P from a different paper feed tray 18a to 18d, thereby continuing the image forming operation without stopping the image forming operation. However, according to the image forming apparatus 100 of this embodiment, the automatic paper feed tray switching function is executed under predetermined conditions, but otherwise the paper feed tray 18 does not switch automatically.

[0047] The image forming apparatus 100 is also equipped with an operation panel 90. Although Figure 1 is a perspective view, the operation panel 90 is located outside the image forming apparatus 100 and can be operated by the user. The operation panel 90 is a touch panel display that shows images of buttons related to operation, and the user can input information related to operation by touching the touch panel display. For example, the image forming apparatus 100 can be operated by operating the operation panel 90. The size of the sheets P held in each paper tray 18a to 18d can also be registered by operating the operation panel 90. The automatic paper tray switching function can also be set by operating the operation panel 90. The operation panel 90 can also display a preview of documents and images to be printed. The operation panel 90 may also have a soft keyboard or the like in addition to the touch panel display.

[0048] Now, with reference to the drawings, the appearance of the operation panel 90 of the image forming apparatus 100 will be described. Figure 2 is an external view of the operation panel of the image forming apparatus according to an embodiment of this disclosure.

[0049] As shown in Figure 2, the control panel 90 displays various buttons for operating the image forming apparatus 100, and the user can make various settings by touching these buttons (display surfaces). For example, by operating the control panel 90, printing (image formation) can be performed on A4 and A3 sized sheets P. Furthermore, multiple sheets (image formation) can be performed by mixing A4 and A3 sized sheets P. For example, the first sheet can be printed in A4 size, the second in A3 size, the third in A4 size, and the fourth in A3 size, resulting in a total of four sheets P. Moreover, multiple sets of these four sheets can be printed. That is, the first sheet can be printed in A4 size, the second in A3 size, the third in A4 size, and the fourth in A3 size, and then the same four sheets can be printed again to print two copies. In this case, image formation is performed on eight sheets P, and the image formation operation is completed.

[0050] Furthermore, the user can configure whether or not to execute the automatic paper tray switching function by operating the control panel 90. If the automatic paper tray switching function is not configured via the control panel 90, the image forming operation will stop if any of the paper trays 18a to 18d supplying sheets P run out during the image forming operation of the image forming unit 60. In this case, the control panel 90 should display a message to inform the user that sheets P have run out. If the automatic paper tray switching function is configured via the control panel 90, if any of the paper trays 18a to 18d supplying sheets P run out during the image forming operation of the image forming unit 60, the system will switch to supplying sheets P from another paper tray 18a to 18d that holds sheets P of the same size, and the image forming operation will continue without stopping. However, under certain conditions, the image forming operation may stop even if the automatic paper tray switching function is configured. Details of these conditions will be described later.

[0051] Next, the control configuration of the image forming apparatus 100 will be described with reference to the drawings. Figure 3 is a schematic block diagram showing the control configuration of the image forming apparatus according to the embodiment of this disclosure.

[0052] As shown in Figure 3, in addition to the above, the image forming apparatus 100 is equipped with a control unit 180 that controls the entire image forming apparatus 100. Note that Figure 3 shows the components related to control in the image forming apparatus 100, and other components are not shown.

[0053] The control unit 180 is a microcomputer such as a CPU (Central Processing Unit) and is equipped with storage devices such as ROM (Read Only Memory), RAM (Random Access Memory), and data-rewritable non-volatile memory. The storage unit 182 consists of these storage devices.

[0054] The memory unit 182 stores in advance control programs and the like for the operation of the image forming apparatus 100. The memory unit 182 also stores data related to images and documents formed by the image forming unit 60 when the image forming apparatus 100 performs an image forming operation, and stores data read by the image reading device 102.

[0055] Furthermore, the memory unit 182 also stores the settings made by the user via the operation panel 90. For example, if the automatic paper tray switching function is set, that setting is stored. Also, if the size of the sheets P held in each paper tray 18a to 18d is set by the user, the memory unit 182 stores which size sheets P are held in each paper tray 18a to 18d.

[0056] The control unit 180 implements the functions of the processing unit 181 and the image formation operation determination unit 183 by executing a control program pre-stored in the storage unit 182. The storage unit 182 also provides the processing unit 181 with a work area for operation, an image memory for storing image data, and a memory for storing document data.

[0057] The processing unit 181 controls the operation of various components by executing a control program pre-stored in the memory unit 182. For example, the image forming unit 60 and the sheet supply unit 80 are controlled by the processing unit 181. The processing unit 181 also receives signals from the operation panel 90 and the sheet sensors 19a to 19d of the paper feed trays 18a to 18d.

[0058] The control unit 180 may be implemented by one or more control / arithmetic devices (CPU, SoC (System on a Chip)). Furthermore, the control unit 180 may be composed of one or more control circuits.

[0059] The image forming operation determination unit 183 determines whether to execute (continue) or stop the image forming operation based on the print instruction (image forming instruction) for sheet P set by the operation panel 90 and the state of sheet P held by each paper feed tray 18a to 18d detected by the sheet sensors 19a to 19d. Based on the determination of the image forming operation determination unit 183, the processing unit 181 determines whether or not to perform the image forming operation in the image forming unit 60, and instructs the operation of the image forming unit 60 and the sheet supply unit 80. The image forming unit 60 and the sheet supply unit 80 operate according to the instructions from the processing unit 181. Specifically, the image transfer unit 50, intermediate transfer belt device 70, secondary transfer device 11, and fixing device 12 in the image forming unit 60 are operated. In addition, the pickup rollers 16a to 16d, transport rollers 13, and registration rollers 14 are driven. In other words, the operation of the drive motors that drive the various rollers is controlled and operated.

[0060] For example, if a user instructs sheet P to form an image (print) by operating the control panel 90, the processing unit 181 operates the image forming unit 60 and the sheet supply unit 80 based on the signal from the control panel 90 to execute the instructed image forming operation. The image forming operation determination unit 183 determines whether or not to execute the image forming operation.

[0061] Here, the image forming operation determination unit 183, when the automatic paper tray switching function is set to run, and the user operates the operation panel 90 to instruct the image forming unit 60 to perform one or more sets of printing in a series of multiple sheets, and the image forming operation of the image forming unit 60 has started, determines whether to continue or stop the image forming operation if the sheets P run out in any of the paper trays 18a to 18d that supply the sheets P to the image forming unit 60. The processing unit 181 then decides whether to continue or stop the image forming operation according to the determination of the image forming operation determination unit 183.

[0062] The following describes the determination by the image forming operation determination unit 183 regarding the continuation and cessation of the image forming operation when the automatic paper tray switching function is enabled.

[0063] First, let's explain the case where the print instruction is to print multiple sets (for example, two sets) of image formation on multiple sheets P of the same size (in this case, A4 size), with one set (one set) being the print. In other words, this is the case when printing two copies of a document consisting of multiple sheets. For example, let's explain the case where, when the image formation operation starts, A4-sized sheets P are supplied from the paper feed tray 18a to the image forming unit 60 by the sheet supply unit 80 (pickup roller 16a, transport roller 13, registration roller 14), and the sheets P held in the paper feed tray 18a run out while the image is being formed in the image forming unit 60. Note that the fact that the sheets P held in the paper feed tray 18a have run out is detected by the sheet sensor 19a, and a detection signal is sent to the control unit 180.

[0064] If the sheet P held in the paper feed tray 18a runs out when that sheet P is the last page of the first set, that is, when the sheet P corresponding to the last page of the first set is supplied to the image forming unit 60, the sheet P held in the paper feed tray 18a runs out, the image forming operation determination unit 183 determines to continue the image forming operation by supplying a sheet P from the paper feed tray 18b, which holds A4-sized sheets P, to the image forming unit 60. Then, the processing unit 181 operates the pickup roller 16b, transport roller 13, and registration roller 14 to supply a sheet P from the paper feed tray 18b to the image forming unit 60. As a result, the first sheet P of the second set is supplied from the paper feed tray 18b. Therefore, even if the paper quality of the sheets P held in the paper feed tray 18a and the paper feed tray 18b are different, all pages in the first set and all pages in the second set will be composed of sheets P of the same paper quality. This prevents problems such as different paper quality in the middle of a multi-page document. Note that the paper quality may differ between the first and second sets because the paper trays 18a and 18b supplied are different.

[0065] On the other hand, if the sheet P held in the paper feed tray 18a runs out and the sheet P that is not the last page of the first set, that is, if the sheet P held in the paper feed tray 18a runs out for reasons other than when the sheet P corresponding to the last page of the first set was supplied to the image forming unit 60, the image forming operation determination unit 183 determines to stop the image forming operation. Then, the processing unit 181 stops the operation of the pickup roller 16a, the transport roller 13, the register roller 14, and the image forming unit 60.

[0066] In this case, the user may be prompted to reinsert the sheet P into the paper tray 18a. For example, a display informing the user to replenish the sheet P may be shown on the operation panel 90. This display will be explained with reference to the drawings. Figure 4 is an external view of the operation panel of an image forming apparatus according to an embodiment of this disclosure, showing the user being prompted to replenish the sheet.

[0067] As shown in Figure 4, if the image forming operation determination unit 183 determines to stop the image forming operation, the processing unit 181 displays a notification display 91 on the operation panel 90 to inform the user to replenish the sheet P on the operation panel 90. The user can also select "Continue printing" on the notification display 91. If the user selects "Continue printing", the image forming operation determination unit 183 determines to continue the image forming operation by supplying the sheet P from the paper feed tray 18b, which holds the A4-sized sheet P, to the image forming unit 60. The processing unit 181 then operates the pickup roller 16b, transport roller 13, and registration roller 14 to supply the sheet P from the paper feed tray 18b to the image forming unit 60. If the user selects "OK" on the notification display 91, the image forming operation remains stopped and the notification display 91 disappears. After this, the user replenishes the sheet P in the paper feed tray 18a and instructs the user to resume the image forming operation, and the image forming operation continues. Furthermore, in this case, the user can prevent the paper quality of the sheets P from being different within the same set by replenishing the paper tray 18a with sheets P of the same type (paper quality) as the sheets P that were held in the paper tray 18a before they ran out.

[0068] As a result, with the image forming apparatus 100 according to this embodiment, when the user has set the automatic paper tray switching function and prints multiple sets of multiple sheets, problems such as the paper quality changing midway through printing the same document can be suppressed. Furthermore, if the paper quality does not change within the same set, the image forming operation can be continued by automatically switching the paper tray 18a that has run out of sheets P, thus enabling efficient work. In addition, if the user selects "continue printing" (execution of the automatic paper tray switching function) after the image forming apparatus 100 issues a command to replenish sheets P, the image forming operation can be continued by switching the paper tray, thus enabling efficient work.

[0069] Next, we will explain the case where the print instruction is to print multiple sets (for example, two sets) of images formed on multiple sheets P of different sizes (here, A4 size and A3 size). In this embodiment, we will explain the case where one set is made by printing four sheets, the first being A4 size, the second A3 size, the third A4 size, and the fourth A3 size, and two sets of these are printed.

[0070] For example, when the image forming operation starts, an A4-sized sheet P is supplied from the paper feed tray 18a to the image forming unit 60 by the sheet supply unit 80 (pickup roller 16a, transport roller 13, register roller 14), and an image is formed on the first sheet P in the image forming unit 60. Then, a second A3-sized sheet P is supplied from the paper feed tray 18c to the image forming unit 60 and an image is formed thereafter. After that, a third A4-sized sheet P is supplied from the paper feed tray 18a to the image forming unit 60 and an image is formed thereafter, and a fourth A3-sized sheet P is supplied from the paper feed tray 18c to the image forming unit 60 and an image is formed thereafter, completing the first set of printing. The process then proceeds to the second set of printing. The first A4-sized sheet P is supplied from the paper feed tray 18a to the image forming unit 60 for image formation, and the second A3-sized sheet P is supplied from the paper feed tray 18c to the image forming unit 60 for image formation. If the sheets P held in the paper feed tray 18c are depleted, a signal is transmitted from the sheet sensor 19c to the control unit 180 indicating that the sheets P have been depleted.

[0071] Subsequently, a third A4-sized sheet P is supplied from the paper feed tray 18a to the image forming unit 60 for image formation. At this point, the image formation operation determination unit 183 determines that the image formation operation should be stopped, and the processing unit 181 stops the image formation operation. Then, as shown in Figure 4, a notification display 91 is displayed on the operation panel 90. In other words, image formation is not performed by supplying sheets of the same size within the same set from different paper feed trays.

[0072] If the user selects "Continue printing" in the notification display 91, the image forming operation determination unit 183 determines to continue the image forming operation by supplying the A3-sized sheet P from the paper feed tray 18d, which holds the sheet P, to the image forming unit 60. The processing unit 181 then operates the pickup roller 16d, transport roller 13, and registration roller 14 to supply the sheet P from the paper feed tray 18d to the image forming unit 60. If the user selects "OK" in the notification display 91, the image forming operation remains stopped and the notification display 91 disappears. After this, the user replenishes the sheet P in the paper feed tray 18c and instructs the image forming operation to resume, and the image forming operation continues.

[0073] On the other hand, during the image forming operation of the fourth sheet of the first set, if the fourth A3-sized sheet P is supplied from the paper feed tray 18c to the image forming unit 60, and the sheet P held in the paper feed tray 18c runs out, and a signal is sent from the sheet sensor 19c to the control unit 180 indicating that the sheet P has run out, the printer proceeds to print the second set, and the first A4-sized sheet P is supplied from the paper feed tray 18a to the image forming unit 60 for image forming. At this time, the paper feed tray 18c does not hold any sheets P, but the image forming operation determination unit 183 determines to continue the image forming operation. The processing unit 181 then operates the pickup roller 16d, the transport roller 13, and the registration roller 14 to supply the sheet P from the paper feed tray 18d to the image forming unit 60. As a result, the second sheet P of the second set is supplied from the paper feed tray 18d. Therefore, even if the paper quality of the sheets P held in paper tray 18c and paper tray 18d differs, all pages of the same size in the first set, and all pages of the same size in the second set, will be composed of sheets P of the same paper quality. This prevents problems such as the paper quality changing midway through a multi-page document. However, since the paper trays 18a, 18b, 18c, and 18d supplied to the first and second sets are different, there is a possibility that the paper quality of sheets P of the same size may differ.

[0074] In the above description, it is assumed that the image forming apparatus 100 is equipped with a paper feed tray 18d that holds A3-sized recording paper P. However, the A3-sized sheet P may be placed in a manual feed tray (not shown) instead of having a paper feed tray 18d. If the presence of an A3-sized sheet P in the manual feed tray is registered using the operation panel 90, then when the sheet P held in the paper feed tray 18c is depleted and the automatic paper feed tray switching function is executed, the sheet P placed in the manual feed tray will be supplied to the image forming unit 60.

[0075] Thus, according to the image forming apparatus 100 of this embodiment, even if the automatic paper tray switching function is set, when creating multiple sets of sets consisting of multiple sheets P by printing multiple sets, if sheets P are supplied from different paper trays for each set of materials, the image forming operation stops before the sheets are supplied, and the user is notified of this. This makes it easy to use the same paper quality for sheets P of the same size in multiple sets of materials. Furthermore, if the same paper quality is not required, the image forming operation can be easily continued, allowing for efficient work.

[0076] Furthermore, according to the image forming apparatus 100 of this embodiment, when printing multiple sheets of the same size, printing stops if the paper runs out within the same set. This prevents the paper quality from changing within the same set. Also, if the paper for a sheet P of a size that has already been printed within the same set runs out, the image forming operation stops. This prevents the paper quality from changing for sheets P of the same size within the same set.

[0077] Furthermore, according to the image forming apparatus 100 of this embodiment, cover setting can be performed during printing. Cover setting is a function that prints the first sheet of a set to be printed as the cover on a specific type of sheet P. For example, if a sheet P held in the paper feed tray 18b is set as the cover, normally the sheet P is supplied to the image forming unit 60 from the paper feed tray 18a, but for the first sheet of the set, the sheet P is supplied to the image forming unit 60 from the paper feed tray 18a.

[0078] Furthermore, the cover settings can be easily configured by the user via the control panel 90. When the cover settings are configured in this way, even if the automatic paper tray switching function is enabled, when printing on multiple sheets P of the same size, including the cover, the sheet P for the cover should be supplied to the image forming unit 60 from the configured paper tray 18b.

[0079] For example, when printing two sets of three sheets, including the cover, if the paper tray 18a runs out of sheets P when image formation is performed on the third sheet P of the first set, the first sheet of the second set is the cover, so the paper tray 18b supplies sheet P to the image forming unit 60. The image forming operation determination unit 183 then determines to continue the image forming operation and supplies the second and third sheets P from the paper tray 18b.

[0080] Thus, according to the image forming apparatus 100 of this embodiment, even when a cover sheet is set, if the paper tray switching function is set, and the sheets P in the paper tray 18a that is not set as a cover sheet run out, the printing operation can be performed efficiently by forming an image on the sheets P held in the paper tray 18b that is set as a cover sheet.

[0081] Next, an example of the operation of the image forming apparatus 100 according to this embodiment will be described with reference to the drawings. Figure 5 is a flowchart showing an example of the operation of the image forming apparatus according to this disclosure.

[0082] When the automatic paper tray switching function is enabled and a print command is issued to print multiple sheets in multiple sets, the image formation operation determination unit 183 determines whether the sheet P to be printed (image formed) is the first sheet in a set (step S1), as shown in Figure 5. If it is the first sheet in a set (step S1: Yes), it determines whether a cover sheet has been set (step S2). If it is not the first sheet in a set (step S1: No), it proceeds to step S3.

[0083] In step S2, if the cover has not been set (step S2: No), proceed to step S3; if the cover has been set (step S2: Yes), proceed to step S4.

[0084] Step S3 determines whether or not this is the first time this size has been printed in the set (Step S3). If it is the first time this size has been printed (Step S3: Yes), the paper tray to supply sheet P to the image forming unit 60 is determined (Step S4). If the size of sheet P is A4, paper tray 18a should be selected; if the size of sheet P is A3, paper tray 18c should be selected and determined. After that, it is determined whether sheet P is held in the determined paper tray (Step S5). If sheet P is not held (Step S5: No), the paper tray is switched (Step S8) and printing is performed (Step S6). In other words, the processing unit 181 continues the image forming operation. Also, if sheet P is held (Step S5: Yes), printing is performed (Step S6).

[0085] After step S6, it is determined whether there are any print instructions (step S7). If there are still print instructions (step S7: Yes), that is, if there is a sheet P to print, the process returns to step S1. If there are no print instructions (step S7: No), that is, if there is no sheet P to print, the process ends.

[0086] Furthermore, in step S3, if it is not the first time printing this size (step S3: No), the paper tray to supply the sheet P to the image forming unit 60 is determined (step S9), and it is determined whether the sheet P is held in the determined paper tray (step S10). If the sheet P is held (step S10: Yes), printing is performed (step S6). In other words, the processing unit 181 continues the image forming operation.

[0087] Furthermore, if sheet P is not held in step S10 (step S10: No), the processing unit 181 stops the image forming operation (step S11), and then displays a notification 91 on the operation panel 90 (step S12). Then, it determines whether there is an instruction to continue printing (step S13), and if there is an instruction to continue printing (step S13: Yes), that is, if the user selects "Continue printing" in the notification 91, the paper tray is switched (step S14) and printing is performed (step S6). On the other hand, if there is no instruction to continue printing in step S13 (step S13: No), that is, if the user selects "OK" instead of "Continue printing" in the notification 91, the process returns to step S10.

[0088] If the user replenishes the selected paper tray with sheet P (step S: Yes), sheet P is supplied from the selected paper tray to the image forming unit 60 and printing is performed (step S6).

[0089] In the following, specific examples (Examples 1 to 5) of forming an image on a sheet P using the image forming apparatus 100 according to this embodiment will be described with reference to the drawings, along with comparative examples.

[0090] Figure 6 is a diagram illustrating Example 1 using an image forming apparatus according to an embodiment of the present disclosure. Figure 7 is a diagram illustrating Example 2 using an image forming apparatus according to an embodiment of the present disclosure. Figure 8 is a diagram illustrating Example 3 using an image forming apparatus according to an embodiment of the present disclosure. Figure 9 is a diagram illustrating Example 4 using an image forming apparatus according to an embodiment of the present disclosure. Figure 10 is a diagram illustrating Example 5 using an image forming apparatus according to an embodiment of the present disclosure.

[0091] (Example 1) In Example 1, we will describe a case in the image forming apparatus 100 where A4-sized sheets P are held in paper feed trays 18a and 18b, respectively, and an image forming instruction is given to perform image forming (printing) on ​​three A4-sized sheets P as one set (one part), and to perform two sets (two parts). The paper held in paper feed trays 18a and 18b are both A4 size, but are sheets P of different paper qualities. Normally, the sheets P held in paper feed tray 18a are supplied to the image forming unit 60, and the automatic paper feed tray switching function is set to be executed. There are four sheets P held in paper feed tray 18a. A sufficient amount of sheets P are held in paper feed tray 18b.

[0092] In the image forming apparatus 100, when an image forming instruction is given, as shown in Figure 6, for the first part (first set), since there are three sheets, the sheets P held in the paper feed tray 18a are supplied to the image forming unit 60 and an image is formed. However, after forming the first image of the second part (second set), the sheets P held in the paper feed tray 18a are depleted and the paper runs out. In this case, the image forming apparatus 100 stops the image forming operation (printing stops), and a notification display 91 is shown on the operation panel 90.

[0093] At this time, if the user wishes to continue the image forming operation using the sheet P held in the paper tray 18b, selecting "Continue printing" in the notification display 91 will supply the sheet P held in the paper tray 18b to the image forming unit 60 and the image forming operation will continue.

[0094] On the other hand, if the user wishes to avoid having different paper types within the same set, they can select "OK" on the notification display 91 and replenish the paper tray 18a with an A4-sized sheet P of the same paper type as the sheet P held in the paper tray 18a. This will allow the sheet P held in the paper tray 18a to be supplied to the image forming unit 60 again, and the image forming operation will continue.

[0095] Next, as Comparative Example 1, we will describe the case where a conventional image forming apparatus is operated under the same conditions as in Example 1. As shown in Figure 6, after forming the first image of the second set, the sheets held in the paper tray are depleted, resulting in a paper shortage. In this case, the conventional image forming apparatus switches the paper tray and supplies sheets from the paper tray holding sheets of a different paper quality to the image forming unit to perform image formation. Therefore, for the second set, the paper quality will differ between the first sheet and the second and third sheets. In this way, sheets of different paper quality will be mixed within the same set. In other words, if sheets of different paper quality are held in each paper tray, it is difficult to avoid the mixing of sheets of different paper quality within the same set.

[0096] In contrast, in the image forming apparatus 100 according to this embodiment, even when sheets P of different paper qualities are held in each of the paper feed trays 18a and 18b, and the automatic paper feed tray switching function is set to run, it is easy to avoid mixing sheets P of different paper qualities within the same set. Furthermore, if the user accepts this, it is also easy to choose to mix sheets P of different paper qualities within the same set.

[0097] (Example 2) In Example 2, we will describe a case in the image forming apparatus 100 where A4-sized sheets P are held in paper feed trays 18a and 18b, respectively, and an image forming instruction is given to perform image forming (printing) on ​​three A4-sized sheets P as one set, and to perform this twice (twice). The paper held in paper feed trays 18a and 18b are both A4 size, but the sheets P are of different paper qualities. Normally, the sheets P held in paper feed tray 18a are supplied to the image forming unit 60, and the automatic paper feed tray switching function is set to be executed. In addition, there are three sheets P held in paper feed tray 18a, which is different from Example 1. A sufficient amount of sheets P are held in paper feed tray 18b.

[0098] In the image forming apparatus 100, when an image forming instruction is given, as shown in Figure 7, for the first part (first set), since there are three sheets, the sheets P held in the paper feed tray 18a are supplied to the image forming unit 60 and an image is formed. After forming the third image of the first set, the sheets P held in the paper feed tray 18a are depleted and the paper runs out. However, since the next sheet P to be formed is the first sheet of the second set, the paper feed tray 18b is switched over, and the sheets P held in the paper feed tray 18b are supplied to the image forming unit 60 to continue the image forming operation. As a result, although the paper quality differs between the first and second sets, the paper quality is the same within the same set. In this case, the user does not need to select a process, and the image forming operation can be performed efficiently.

[0099] Next, as Comparative Example 2, we will describe the case where a conventional image forming apparatus is operated under the same conditions as in Example 2. As shown in Figure 7, after forming the third image of the first set, the sheets held in the paper tray are depleted, resulting in a paper shortage. In this case, a conventional image forming apparatus switches the paper tray and supplies sheets from a paper tray holding sheets of a different paper quality to the image forming unit to perform image formation. Therefore, the same results are obtained in a conventional image forming apparatus as in the image forming apparatus 100 according to this embodiment.

[0100] (Example 3) In Example 3, we will describe a case where, in the image forming apparatus 100, A4-sized sheets P are held in the paper feed tray 18a, and A3-sized sheets P are held in the paper feed trays 18c and 18d, respectively, and an image forming (printing) instruction is given to perform two sets (two copies) of image forming (printing) on ​​sheets P, with the first sheet being A4 size, the second A3 size, the third A4 size, and the fourth A3 size. Note that the paper held in the paper feed trays 18c and 18d are both A3 size, but are sheets P of different paper qualities. Normally, when an image forming instruction is given for A3-sized sheets P, the sheet P held in the paper feed tray 18c is supplied to the image forming unit 60, and the automatic paper feed tray switching function is set to be executed. Also, there are three sheets P held in the paper feed tray 18c. Note that a sufficient amount of sheets P are held in the paper feed trays 18a and 18d. There are four or more sheets P held in the paper feed tray 18a.

[0101] In the image forming apparatus 100, when an image forming instruction is given, as shown in Figure 8, for the first part (first set), the first sheet P is supplied from the paper feed tray 18a to the image forming unit 60, the second sheet P is supplied from the paper feed tray 18c to the image forming unit 60, the third sheet P is supplied from the paper feed tray 18a to the image forming unit 60, and the fourth sheet P is supplied from the paper feed tray 18c to the image forming unit 60, completing the image forming of the first set, and the image forming operation for the second set continues. For the second set, the first sheet P is supplied from the paper feed tray 18a to the image forming unit 60, and the second sheet P is supplied from the paper feed tray 18c to the image forming unit 60, but this depletes the sheet P held in the paper feed tray 18c, resulting in a paper out. At this point, the third sheet P is A4 size and the paper feed tray 18a is holding sheet P, so the image forming operation continues and the third sheet P is supplied from the paper feed tray 18a to the image forming unit 60. Then, since the fourth A3 size sheet P is not held in the paper feed tray 18c, the image forming apparatus 100 stops the image forming operation (printing stops), and a notification display 91 is displayed on the operation panel 90.

[0102] At this time, if the user wishes to continue the image forming operation using the A3-sized sheet P held in the paper feed tray 18d, selecting "Continue Printing" on the notification display 91 will supply the sheet P held in the paper feed tray 18d to the image forming unit 60 and the image forming operation will continue. Alternatively, the A3-sized sheet P may be placed in the manual feed tray instead of the paper feed tray 18d; in that case, the sheet P placed in the manual feed tray will be supplied to the image forming unit 60.

[0103] On the other hand, if the user wants to avoid having different paper qualities for the same size within the same set, they can select "OK" on the notification display 91 and replenish the paper tray 18c with an A3-sized sheet P of the same paper quality as the sheet P held in the paper tray 18c. This will supply the fourth A3-sized sheet P of the second set from the paper tray 18c to the image forming unit 60, and the image forming operation will be performed.

[0104] Next, as Comparative Example 3, we will describe the case where a conventional image forming apparatus is operated under the same conditions as in Example 3. As shown in Figure 8, after forming the second image of the second set, the paper tray holding the A3-sized sheets runs out of sheets, resulting in a paper shortage. In this case, the conventional image forming apparatus switches the paper tray when supplying the next A3-sized sheet P to the image forming unit, and supplies a sheet from the paper tray holding sheets of a different paper quality to the image forming unit to perform image formation. Therefore, for the second set, the first and third A4-sized sheets are of the same paper quality, but the second and fourth A3-sized sheets are of different paper quality, resulting in a mix of sheets of different paper quality within the same set of the same size. Thus, when each paper tray holding sheets of the same size holds sheets of different paper quality, it is difficult to avoid the mixing of sheets of different paper quality within the same set of the same size.

[0105] In contrast, in the image forming apparatus 100 according to this embodiment, even when different types of paper P are held in each of the paper feed trays 18c and 18d that hold sheets P of the same size, and the automatic paper feed tray switching function is set to run, it is easy to avoid mixing different types of paper P of the same size within the same set. Furthermore, if the user accepts this, it is also easy to select the option of mixing different types of paper P of the same size within the same set.

[0106] (Example 4) In Example 4, we describe a case where, in the image forming apparatus 100, an A4-sized sheet P is held in the paper feed tray 18a, and A3-sized sheets P are held in the paper feed trays 18c and 18d, respectively, and an image forming (printing) instruction is given to perform two sets (two copies) of this, with the first sheet being A4 size, the second A3 size, the third A4 size, and the fourth A3 size. Note that the paper held in the paper feed trays 18c and 18d are both A3 size, but are sheets P of different paper qualities. Normally, when an image forming instruction is given for an A3-sized sheet P, the sheet P held in the paper feed tray 18c is supplied to the image forming unit 60, and the automatic paper feed tray switching function is set to execute. Also, there are two sheets P held in the paper feed tray 18c, which is different from Example 3. Note that a sufficient amount of sheets P are held in the paper feed trays 18a and 18d.

[0107] In the image forming apparatus 100, when an image forming instruction is given, as shown in Figure 9, for the first part (first set), the first sheet P is supplied from the paper feed tray 18a to the image forming unit 60, the second sheet P is supplied from the paper feed tray 18c to the image forming unit 60, the third sheet P is supplied from the paper feed tray 18a to the image forming unit 60, and the fourth sheet P is supplied from the paper feed tray 18c to the image forming unit 60, completing the image forming of the first set. At this point, since the fourth sheet P has been supplied from the paper feed tray 18c to the image forming unit 60, the paper held in the paper feed tray 18c is depleted, resulting in a paper out. In this case, the next A3-sized sheet P to be supplied is not the first set but the second set, so when the next A3-sized sheet P is supplied to the image forming unit 60, the system switches and supplies the A3-sized sheet P from the paper feed tray 18d to the image forming unit 60.

[0108] In the second part (second set) of image formation, the first sheet P is supplied from the paper feed tray 18a to the image forming unit 60, the second sheet P is supplied from the paper feed tray 18d to the image forming unit 60, the third sheet P is supplied from the paper feed tray 18a to the image forming unit 60, and the fourth sheet P is supplied from the paper feed tray 18d to the image forming unit 60, thus completing the image formation of the second set.

[0109] As a result, while the paper quality of the A3-sized sheets P differs between the first and second sets, they will be the same within the same set. Furthermore, in this case, the user does not need to select a processing method, allowing for efficient image formation.

[0110] Next, as Comparative Example 4, we will describe the case where a conventional image forming apparatus is operated under the same conditions as in Example 4. As shown in Figure 9, after forming the fourth image of the first set, the A3-sized sheets held in the paper tray are depleted, resulting in a paper shortage. In this case, the conventional image forming apparatus switches to another paper tray that holds A3-sized sheets, and supplies sheets of a different paper quality from the A3-sized sheets of the first set to the image forming unit to perform image formation. Therefore, the same results are obtained in the conventional image forming apparatus as in the image forming apparatus 100 according to this embodiment.

[0111] (Example 5) In Example 5, we will describe a case in the image forming apparatus 100 where A4-sized sheets P are held in paper feed trays 18a and 18b, respectively. One set consists of image forming (printing) on ​​three A4-sized sheets P, and this is performed in two sets (two copies), with the first sheet of each set being the sheet P designated as the cover sheet. The sheets P held in paper feed trays 18a and 18b are both A4 size but of different paper qualities. Normally, the sheet P held in paper feed tray 18a is supplied to the image forming unit 60, and the automatic paper feed tray switching function is set to be executed. Furthermore, a cover sheet is set, and the sheet P used as the cover (the sheet P designated as the cover) is set to be the sheet P held in paper feed tray 18b. There are two sheets P held in paper feed tray 18a. A sufficient amount of sheets P are held in paper feed tray 18b.

[0112] In the image forming apparatus 100, when an image forming instruction is given, as shown in Figure 10, for the first part (first set), the first sheet becomes the cover, so the sheet P held in the paper feed tray 18b is supplied to the image forming unit 60 and an image is formed. Then, for the second and third sheets, the sheets P held in the paper feed tray 18a are supplied to the image forming unit 60 and images are formed, completing the image forming of the first set. At this point, since the third sheet P has been supplied to the image forming unit 60 from the paper feed tray 18a, the paper P held in the paper feed tray 18a is depleted and the paper runs out, but the image forming of the second part (second set) proceeds. For the second set, first, the first sheet becomes the cover, so the sheet P held in the paper feed tray 18b is supplied to the image forming unit 60 and an image is formed. Then, even though the sheet P held in the paper feed tray 18a is gone, the image forming operation continues without stopping, and sheets P are supplied from the paper feed tray 18b to the image forming unit 60 for the second and third sheets (which are not the cover) to perform image forming. This eliminates the need for the user to select a process, and the image forming operation can be performed efficiently.

[0113] Next, as Comparative Example 5, we will describe the case where a conventional image forming apparatus is operated under the same conditions as in Example 5. As shown in Figure 10, after forming the third image of the first set, the paper tray runs out of sheets other than the cover sheet. In this case, the conventional image forming apparatus switches the paper tray and supplies a sheet from the paper tray holding the cover sheet to the image forming unit to perform image forming. Therefore, the conventional image forming apparatus will produce the same results as the image forming apparatus 100 according to this embodiment.

[0114] This disclosure is not limited to the embodiments described above and can be implemented in various other ways. Therefore, such embodiments are merely illustrative in all respects and should not be constrained. The scope of this disclosure is defined by the claims and is not restricted by the text of the specification. Furthermore, any variations or modifications falling within the equivalent scope of the claims are all within the scope of this disclosure. [Explanation of Symbols]

[0115] 1. Optical scanning device 2. Developing device 3. Photoconductor drum 4. Drum cleaning device 5. Charger 6. Intermediate transfer roller 9. Cleaning device 11. Secondary transfer device 11a Secondary transfer roller 12 Fixing device 13 Conveyor rollers 14 Registrola 16a~16d Pickup roller 17 Discharge roller 18a~18d Paper feed tray 19a~19d Seat Sensor 31 Fixing roller 32 Pressure rollers 50 Image transfer section 60 Image forming unit (image forming means) 80 Sheet supply unit (paper supply means) 90. Operation panel (display means) 91. Notice / Display (Display regarding response method) 70 Intermediate transfer belt device 71 Intermediate transfer belt 72 Intermediate transfer drive roller 73 Intermediate transfer driven roller 100 Image forming apparatus 101 Image forming apparatus main unit 102 Image reading device 130 Image reading unit 130a Manuscript placement stand 130b Manuscript reading unit 130c scanning optical system 140 Discharge section 141 Sheet ejection tray 160 Document feeder 161 Manuscript Tray 162 Document Output Tray 180 Control Unit 181 Processing Unit 182 Storage section 183 Image forming operation judgment unit Sr Sheet Reversal Path S Sheet transport path TN transfer nip region G Manuscript P Sheet (Paper) P1 transport route Pa, Pb, Pc, Pd Image Station

Claims

1. An image forming apparatus comprising: an image forming means for forming an image on paper; a plurality of paper trays, each holding a sheet of paper; and a paper supply means for drawing out sheets of paper one by one from the paper trays and supplying them to the image forming means, When an image formation instruction is received to form multiple sets of images on multiple sheets of paper, the paper supply means supplies paper from a predetermined paper tray to the image forming means. If, during the image formation process as instructed, the paper held in the predetermined paper tray runs out, the image forming means stops the image forming operation. An image forming apparatus characterized in that, when the final sheet of paper in a predetermined set in the image forming instruction is supplied to the image forming means, if the paper in the predetermined paper tray runs out, the paper supply means supplies paper to the image forming means from a different paper tray than the predetermined paper tray, and the image forming means continues the image forming operation.

2. An image forming apparatus according to claim 1, When creating an image on multiple sheets of paper, it is possible to set the first sheet as the cover page. When an image formation instruction is received to form images on multiple sheets of paper with the aforementioned cover settings, the paper supply means supplies paper from a predetermined paper tray to the image forming means. An image forming apparatus characterized in that, during the image forming process in the image forming instruction, if the paper to be used as the cover is supplied from the predetermined paper tray and the paper held in the predetermined paper tray runs out, the paper supply means supplies paper to the image forming means from a paper tray different from the predetermined paper tray, and the image forming means continues the image forming operation.

3. An image forming apparatus comprising: an image forming means for forming an image on paper; a plurality of paper trays, each holding a sheet of paper; and a paper supply means for drawing out sheets of paper one by one from the paper trays and supplying them to the image forming means, The aforementioned multiple paper trays include multiple combinations of paper trays that hold paper of the same size, and different combinations of paper trays that hold paper of different sizes. When an image formation instruction is received to form images on multiple sets of paper, each set containing multiple sheets of paper of different sizes, the paper supply means supplies paper from a predetermined paper tray to the image forming means according to the paper sizes specified in the image formation instruction. An image forming apparatus characterized in that, in the process of forming an image of a predetermined set in the image forming instruction, if the paper held in the predetermined paper tray runs out, and if image forming on paper of the same size as the runout paper has not yet been completed, the image forming means stops the image forming operation.

4. An image forming apparatus according to claim 3, An image forming apparatus characterized in that, in the middle of image forming of a predetermined set in the image forming instruction, if the paper held in the paper tray within the predetermined paper feed tray runs out, and image forming of paper of the same size as the runout paper has been completed, the paper supply means supplies paper to the image forming means from another paper feed tray that holds paper of the same size but is different from the predetermined paper feed tray, and the image forming means continues the image forming operation.

5. An image forming apparatus according to claim 1 or claim 3, Equipped with display means, An image forming apparatus characterized in that, if the image forming means stops the image forming operation in the middle of image formation, the display means displays information on how to respond.

Images