Image forming apparatus

Abstract

To solve such a problem that there may be a case in which it takes time to acquire information on a type of a recording material included in a job in advance, and there is such a risk that image formation timing delays and productivity deteriorates.SOLUTION: An image formation apparatus for forming an image on a recording material by fixing a toner image on the recording material comprises: an acquisition unit which acquires basis weight information of the recording material; and a temperature control unit which controls a temperature of a heating rotor on the basis of the basis weight information. When the prescribed number of pieces of basis weight information can be acquired within a prescribed time after inputting a printing start signal of a job forming an image to the prescribed number of recording materials, the temperature control unit controls the temperature of the heating rotor on the basis of the basis weight information of the prescribed number of recording materials. When the prescribed number of pieces of basis weight information cannot be acquired within the prescribed time, the temperature control unit controls the temperature of the heating rotor on the basis of the basis weight information of the recording materials in the number smaller than the prescribed number.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The image forming apparatus has a fixing device that fixes an unfixed toner image on a recording material to the recording material.

[0002] A fixing device having a heating rotating body with a heat source for heating an unfixed toner image and a pressure roller for pressing the heating rotating body is known (Patent Document 1). The fixing device also has a contact-separation mechanism that enables the pressure roller to move between a position where it contacts the heating rotating body and a position where it is separated from the heating rotating body. When the pressure roller is in the position where it contacts the heating rotating body, a nip portion is formed by the heating rotating body and the pressure roller. When a recording material carrying an unfixed toner image is conveyed to this nip portion, the heat and pressure required for fixing are applied in the nip portion, and the toner on the recording material is fixed.

[0003] When forming a toner image on a recording material, the amount of heat required for fixing the toner image varies depending on the type of the recording material. Patent Document 1 discloses a technique for changing the temperature of the heating rotating body according to the type of the recording material. By this, the amount of heat applied to the toner image on the recording material is appropriately controlled.

[0004] When performing a job in which a plurality of types of recording materials are mixed in one job, if the fixing temperature is changed according to the type of the recording material, the fixing temperature must be changed every time the recording material is changed. Then, the number of printed sheets per unit time (productivity) will decrease. Therefore, it is proposed to acquire in advance information on the types of recording materials included in the job and determine the fixing temperature based on that information. By this, an optimal fixing temperature can be set for the recording materials included in the job, and it becomes possible to reduce the switching of the fixing temperature and suppress the decrease in productivity.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] When acquiring information about the types of recording materials included in a job in advance, the acquisition process may take time if the information to be acquired is large or otherwise complex. Normally, image formation begins only after the acquisition of the recording material information is complete. Therefore, image formation will not start until the acquisition of the recording material information is finished. This can delay the timing of image formation and potentially reduce productivity. [Means for solving the problem]

[0007] In view of the above problems, the present invention provides an image forming apparatus comprising a heating rotating body that heats a recording material, a pressurizing rotating body that pressurizes the heating rotating body, the heating rotating body together with the pressurizing rotating body to form a nip portion and apply heat and pressure to the recording material carrying a toner image at the nip portion, thereby fixing the toner image to the recording material, and forming an image on the recording material by fixing the toner image to the recording material, wherein the apparatus comprises an acquisition unit that acquires basis weight information of the recording material, a temperature control unit that controls the temperature of the heating rotating body based on the basis weight information, and if a predetermined number of basis weight information can be acquired within a predetermined time after a print start signal for a job to form an image on a predetermined number of recording materials is input, the temperature control unit controls the temperature of the heating rotating body based on the basis weight information of the predetermined number of recording materials, and if a predetermined number of basis weight information cannot be acquired within a predetermined time after a print start signal for the job is input, the temperature control unit controls the temperature of the heating rotating body based on the basis weight information of a number of recording materials less than the predetermined number. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress delays in the timing of image formation and to suppress a decrease in productivity. [Brief explanation of the drawing]

[0009] [Figure 1] This is the overall view. [Figure 2] This is a system block diagram. [Figure 3] This is an explanatory diagram of the control panel. [Figure 4] This is an explanatory diagram of the bookbinding process settings. [Figure 5] (a) to (c) are diagrams illustrating the layout method of images during the bookbinding process. [Figure 6] This is an explanatory diagram of lookahead control. [Figure 7] This is a flowchart of the embodiment. [Modes for carrying out the invention]

[0010] <Overall Structure> Figure 1 is a configuration diagram showing the cross-sectional structure of the main part of the image forming system according to the first embodiment of this embodiment. As shown in Figure 1, the image forming system consists of an image forming apparatus 10 and a finisher 500. The image forming apparatus 10 includes an image reader 200 that reads an image from a document and a printer 350 that forms the read image on paper.

[0011] The document feeder 100 feeds documents placed face up on the document tray 101 one by one from the first page to the left in Figure 1, and transports them from left to right across the platen glass 102 via a curved path, passing through predetermined flow scanning positions. Afterward, the documents are discharged towards the external output tray 112. The flow scanning positions are predetermined reading positions on the platen glass of the image reader 200, where the scanner unit 104 is fixed. As the document passes through the flow scanning positions on the platen glass 102 from left to right, the document image is read by the scanner unit 104, which is held at the position corresponding to the flow scanning position. As the document passes through the flow scanning positions, the reading surface of the document is illuminated by the light from the lamp 103 of the scanner unit 104, and the reflected light from the document is guided to the lens 108 via mirrors 105, 106, and 107. The light that passes through this lens 108 is then imaged onto the imaging surface of the image sensor 109.

[0012] In this way, by transporting the document so that it passes through the flow scanning position from left to right, the document scanning is performed with the direction perpendicular to the document transport direction as the main scanning direction and the transport direction as the sub-scanning direction. That is, as the document passes through the flow scanning position, the entire document image is read by the image sensor 109 one line at a time in the main scanning direction, while the document is transported in the sub-scanning direction. The optically read image is converted into image data by the image sensor 109 and output. The image data output from the image sensor 109 is input as a video signal to the exposure unit 110 of the printer 350.

[0013] The exposure unit 110 of the printer 350 modulates and outputs laser light based on the video signal input from the image reader 200. This laser light is scanned by the polygon mirror 110a and irradiated onto the photosensitive drum 111. An electrostatic latent image corresponding to the scanned laser light is formed on the photosensitive drum 111. Here, when the document is fixed and read, the exposure unit 110 outputs laser light so that an upright image (not a mirror image) is formed. This electrostatic latent image on the photosensitive drum 111 is made visible as a developer image by the developer supplied from the developer unit 113.

[0014] Meanwhile, paper fed from the upper cassette 114 or lower cassette 115 equipped in the printer 350 by the pickup rollers 127 and 128 is transported to the registration roller 126 by the paper feed rollers 129 and 130. When the leading edge of the paper reaches the registration roller 126, the registration roller 126 is driven at an arbitrary timing and, at a timing synchronized with the start of laser irradiation, the paper is transported between the photosensitive drum 111 and the transfer unit 116. The developer image formed on the photosensitive drum 111 is transferred onto the fed paper by the transfer unit 116. The paper on which the developer image has been transferred is transported to the fuser unit 117, where the fuser unit 117 fixes the toner image onto the recording material, which carries the toner image, by applying heat and pressure to the nip section formed by a heating rotating body and a pressurizing rotating body. The fuser unit has a heating rotating body, and the heating rotating body generates heat, thereby applying heat to the recording material. The temperature of the heating rotating body is set to a target temperature according to the type and basis weight of the recording material. The temperature control unit, described later, controls the temperature of the heating rotating body so that it reaches the target temperature. The paper that has passed through the fixing unit 117 is discharged from the printer 350 towards the outside of the image forming apparatus (finisher 500) via the flapper 121 and discharge roller 118.

[0015] Here, when discharging the paper with its image forming surface facing downward (face down), the paper that has passed through the fixing unit 117 is once guided into the reverse path 122 by the switching operation of the flapper 121. Then, after the trailing edge of the paper has passed through the flapper 121, the paper is switched back and discharged from the printer 350 by the discharge roller 118. This paper discharge mode is called reverse paper discharge. This reverse paper discharge is performed when forming an image read using the original document feeder 100 or when forming an image output from a computer, etc., when forming images in order from the first page, and the paper order after the discharge is in the correct page order. Also, when a hard paper such as OHP paper is fed from the manual paper feed unit 125 and an image is formed on this paper, the paper is discharged by the discharge roller 118 with the image forming surface facing upward (face up) without guiding the paper into the reverse path 122. Further, when duplex recording for forming images on both sides of the paper is set, after guiding the paper into the reverse path 122 by the switching operation of the flapper 121, the paper is conveyed to the duplex conveyance path 124. Then, control is performed to feed the paper guided to the duplex conveyance path 124 again between the photosensitive drum 111 and the transfer unit 116 at the above-mentioned timing.

[0016] The process from when the recording material fed from this upper cassette 114 or lower cassette 115 passes through the fixing unit 117 until an image is formed on the recording material is defined as image formation.

[0017] The paper discharged from the printer 350 of the image forming apparatus 10 is sent to the finisher 500.

[0018] <Finisher> Next, the configuration of the finisher 500 will be described using FIG. 1.

[0019] The finisher 500 sequentially takes in the paper discharged from the image forming apparatus 10, performs processes such as aligning and bundling the multiple taken-in papers into one bundle, stapling the trailing edge of the bundled paper stack with staples, punching holes near the trailing edge of the taken-in paper, sorting process, non-sorting process, binding process, and other post-sheet processes.

[0020] The finisher 500 takes in the paper discharged from the image forming apparatus 10 by the inlet roller pair 511, and the paper taken in by the inlet roller pair 511 is sent to the sorting path 522.

[0021] Also, a switching flapper 514 is disposed downstream of the sorting path 522, and the switching flapper 514 is a flapper that switches the path between the processing tray 550 and the binding path 523.

[0022] The paper guided to the binding path 523 is conveyed to the binding processing tray 580 via the conveying roller pair 801. A binding inlet sensor (not shown) is provided in the middle of the binding path 523. The binding processing tray 580 is provided with a sheet gripping member 802 and a movable paper positioning member 805. Also, an intermediate stapler 820 is provided, and the intermediate stapler 820 is configured to perform stapling on the stack of papers stored in the binding processing tray 580. A folding roller pair 810 and a protruding member 830 protruding at a position facing the folding roller pair 810 are provided downstream of the intermediate stapler 820. By protruding the protruding member 830 toward the stack of papers stored in the binding processing tray 580, the stack of papers stored in a bundle in the binding processing tray 580 is pushed out between the folding roller pair 810. The folding roller pair 810 folds the stack of papers and conveys the stack of papers downstream. The folded stack of papers is guided to a conveying path and conveyed downstream via the folding conveying roller 811. A press unit 860 is provided further downstream of the folding conveying roller 811, and the stack of papers is conveyed to the press unit 860. By applying pressure to the folding portion by the press unit 860, the fold of the stack of papers is ensured.

[0023] After the stack of papers is woven by the press unit 860, the stack of papers is discharged to the binding tray 850 by the folding conveying roller 811.

[0024] Here, the paper ejected from the image forming apparatus 10 is sequentially loaded onto the aforementioned binding tray 580. However, as explained earlier, the paper is folded so that the middle of the paper protrudes, so the first paper loaded becomes the inside when folded, and the last paper loaded becomes the outside when folded. Therefore, when binding, the paper that will become the cover needs to be on the outside, so the cover is image-formed last and loaded onto the binding tray.

[0025] (Overall system block diagram) Next, the configuration of the controller that controls the entire image forming system and the overall system block diagram will be explained with reference to Figure 2. Figure 2 is a block diagram showing the configuration of the controller that controls the entire image forming system as shown in Figure 1.

[0026] As shown in Figure 2, the controller has a CPU circuit unit 900, which incorporates a CPU 901, ROM 902, and RAM 903. The CPU 901 is the CPU that performs the basic control of the entire image system, and is connected to the ROM 902, where the control program is written, and the RAM 903 for processing by an address bus and a data bus. The CPU 901 comprehensively controls each control unit 911, 921, 904, 922, 931, 941, and 951 by the control program stored in the ROM 902. The RAM 903 temporarily holds control data and is also used as a workspace for calculation processing associated with the control.

[0027] The document feeder control unit 911 drives and controls the document feeder 100 based on instructions from the CPU circuit unit 900. The image reader control unit 921 drives and controls the scanner unit 104, image sensor 109, etc., and transfers the image signal output from the image sensor 109 to the image signal control unit 922.

[0028] The image signal control unit 922 converts the analog image signal from the image sensor 109 into a digital signal, performs various processing steps, converts this digital signal into a video signal, and outputs it to the printer control unit 931. It also performs various processing steps on the digital image signal input from the computer 990 via the external I / F 904, converts this digital image signal into a video signal, and outputs it to the printer control unit 931. The processing operations of the image signal control unit 922 are controlled by the CPU circuit unit 900. The printer control unit 931 controls the exposure unit 110 and the printer 350 based on the input video signal to perform image formation and paper transport.

[0029] The finisher control unit 951 is mounted on the finisher 500 and controls the drive of the entire finisher by exchanging information with the CPU circuit unit 900.

[0030] The operation display control unit 941 exchanges information between the operation display device 600 and the CPU circuit unit 900. The operation display device 600 has multiple keys for setting various functions related to image formation, a display unit for displaying information indicating the setting status, and the like. It outputs key signals corresponding to the operation of each key to the CPU circuit unit 900, and displays corresponding information on the operation display device 600 based on the signals from the CPU circuit unit 900.

[0031] (How to submit a bookbinding job) Next, the configuration of the control panel of this device will be explained using Figure 3. The control panel 600 consists of a touch panel 620 and keypads 604-612 and 614, an ID key 613, a clear key 615, a reset button 616, a start button 602, and a stop button 603.

[0032] The touch panel 620 consists of a liquid crystal display screen and a detection unit capable of acquiring the XY coordinates pressed by the user. The numeric keypads 604-612 and 614 are for inputting numerical values ​​such as the number of job copies and magnification. The ID key 613 is for inputting the user's management number for using this device. The clear key 615 is for clearing the values ​​entered from the numeric keypads 604-612 and 614.

[0033] The reset button 616 is used to return the job settings entered via the touch panel 620 to their default values. The start button 602 is used to start a job based on the job settings entered via the touch panel 620. The stop button 603 is used to stop a job that has been started by the start button 602.

[0034] Next, using Figure 4, we will explain how to specify the paper type when performing the bookbinding process with this device.

[0035] Figure 4(a) shows the initial screen when executing a copy job from the reader unit during the bookbinding process using this device. On this screen, you can set whether or not to use the advanced mode, which includes the bookbinding process. Pressing the advanced mode button on the touch panel 620 will transition to Figure 4(b).

[0036] Figure 4(b) shows the detailed settings screen for the application mode in Figure 4(a), where you can select application mode functions to set for jobs such as mixed paper loads and bookbinding. Multiple application modes can be set. Pressing "Bookbinding" on the touch panel 620 will take you to Figure 4(c). Pressing "Close" will return you to Figure 4(a).

[0037] Figure 4(c) is a detailed settings screen for selecting which paper feed tray to use for the cover when performing the binding process. Selection is possible from paper feed trays 1 and 2, and the manual feed tray. Pressing "Next" on the touch panel 620 will proceed to Figure 4(d).

[0038] Figure 4(d) shows the detailed settings screen for configuring whether or not to perform stapling during saddle stitching with the finisher 500 when performing bookbinding. Selecting "Saddle Stitch" on the touch panel 620 specifies that the pages will be stapled in the middle before being folded. Selecting "Do not saddle stitch" specifies that the pages will be folded without stapling. Pressing "Next" on the touch panel 620 will take you to Figure 4(e).

[0039] Figure 4(e) is the detailed settings screen for specifying whether to create a copy image on each side of the cover paper when performing the binding process. You can set whether or not to copy each side of the "front of the front cover," "back of the front cover," "front of the back cover," and "back of the back cover." Pressing "OK" here sets the specified settings as a job and returns you to Figure 4(b).

[0040] With the above settings, when performing the binding process, you can configure whether or not to feed the cover from a different paper feed tray than the main text, whether or not to perform saddle stitching, and whether or not to copy each side of the cover.

[0041] In the above example, the job settings were made using the touch panel 620, but the embodiment is not limited to this, and the settings may also be made on the screen of a PC terminal that sends the print job to the image forming apparatus.

[0042] <Image layout during bookbinding process> Figures 5(a) to 5(c) illustrate the layout method for each page of the original document image when a binding process is performed to attach a cover to a left-opening bound document and the paper is output to the binding tray 850.

[0043] When paper is to be ejected to the binding tray 850, the images of each page of the original document shown at 1101 in Figure 5(a) are laid out and held on the image signal control unit 922 as shown at 1102 in Figure 5(b). Once the layout is complete, the images are printed in order from the images of the pages corresponding to the body of the book to the images of the pages corresponding to the cover of the book. If the arrangement of the laid-out images is as shown in Figure 5(b), the printer control unit 931 first prints the front (body) of the first page, the back (body) of the first page, the front (body) of the second page, the back (body) of the second page, the front (body) of the third page, and the back (body) of the third page. Finally, the printer control unit 931 prints the front (cover) and back (back cover) of the fourth page. After the printed paper is transported to the finisher 500, it is sequentially accumulated inside the binding processing tray 580. After the binding process is performed, the folding process is performed and the paper is ejected to the binding tray 850.

[0044] <Productivity Priority Mode and Image Quality Priority Mode> The image forming apparatus of this embodiment has a productivity-prioritizing mode that prioritizes productivity and an image quality-prioritizing mode that prioritizes image quality, and image forming can be performed using these modes.

[0045] The mode used for image formation can be selected from the touch panel 620 of the operation unit 600. Furthermore, it may also be selectable from the external I / F 904.

[0046] When recording materials with different basis weights or paper types are mixed in a single job, changing the target temperature of the fixing unit 117 in response to a change in basis weight will reduce productivity. To suppress this decrease in productivity, the productivity priority mode performs fixing at a fixing temperature that ensures proper fixing for recording materials with different basis weights. Therefore, the change in fixing temperature is minimal, and the decrease in productivity can be suppressed.

[0047] On the other hand, the image quality priority mode is a mode that prioritizes the image quality of the resulting image. Therefore, it adjusts the temperature more precisely according to the basis weight than the productivity priority mode. The image quality of the toner image formed on the recording material depends on the amount of heat applied to the toner image. There is an optimal temperature for each basis weight of the recording material, and applying this optimal temperature can improve image quality. The image quality priority mode sets the temperature precisely according to the basis weight and type (coated or uncoated paper) of the recording material. Therefore, when printing a mixed job with different basis weights in image quality priority mode, the fixing temperature is changed more often than in productivity priority mode. When changing the fixing temperature, time must be allocated for the temperature change, which tends to lower productivity. Thus, when printing a mixed job in image quality priority mode compared to productivity priority mode, the image quality tends to be higher when printed in image quality priority mode than in productivity priority mode. Also, when printing in image quality priority mode, productivity tends to be lower compared to printing in productivity priority mode.

[0048] <Information about the recording material is acquired in advance before image formation begins.> This section explains how to acquire information about the recording material before image formation. This involves receiving as much information as possible about the recording material before starting image formation, and then selecting the optimal fixing temperature table from the received information.

[0049] First, the print content is input from the external I / F 904 or the operation display control unit 941. After the print content is input, when the start button 602 on the operation unit 600 is pressed, a print start signal is input to the CPU 901. The print job is started. Once the print job is started, the input print content is transmitted to the CPU 901 in the image forming apparatus. The print content includes information on the basis weight and type of the recording material. The CPU 901 has an acquisition unit that can acquire this information and can grasp the basis weight information of the recording material for the print job. Note that the print job information is acquired in order of printing.

[0050] Using the fixing temperature table shown in Figure 6, we will explain how to select the fixing temperature table when a predetermined number of sheets (15 sheets in this embodiment) are received.

[0051] Here, the prescribed number is set at 15, but it is not limited to 15; the number can be any number depending on the engine configuration, etc.

[0052] The CPU 901 has a temperature control unit that controls the target temperature of the heating rotating body of the fixing unit 117. The temperature control unit then sets the optimal temperature of the heating rotating body based on the basis weight information of a predetermined number of recording materials acquired by the acquisition unit. As will be described later, the optimal temperature here refers to setting the temperature to the temperature table with the shortest temperature switching time.

[0053] Figure 6 shows three types of temperature tables. Each table lists the set temperatures for various types of paper. For example, in temperature table 1, if the paper is thin paper, the temperature is set to control the fuser unit 117 at 150 degrees.

[0054] Here, we will explain how to select the fuser temperature table using a printout with mixed paper types as an example, where the first 10 sheets are plain paper and the following 5 sheets are coated paper.

[0055] The CPU 901 determines, based on previously acquired information about the recording material, that the job consists of, for example, plain paper and coated paper. Note that the information the CPU 901 uses for its determination may also be basis weight. Next, the CPU 901 calculates the temperature change for plain paper and coated paper for each fixing temperature table and selects the table with the smallest temperature change. Specifically, in fixing temperature table 1 in Figure 6, the temperature of plain paper is 150 degrees and the temperature of coated paper is 170 degrees, so the temperature change is 20 degrees. Similarly, in fixing temperature table 2, the temperature of plain paper is 160 degrees and the temperature of coated paper is 170 degrees, so the temperature change is 10 degrees. Similarly, in fixing temperature table 3, the temperature of plain paper is 170 degrees and the temperature of coated paper is 170 degrees, so there is no temperature change. Therefore, the CPU 901 selects fixing temperature table 3.

[0056] Furthermore, in this embodiment, in order to simplify the explanation, we have described a method for selecting a temperature table without considering the order in which the paper information acquired by the acquisition unit before the start of the print job was received (in this case, plain paper to coated paper) or the number of sheets received (in this case, 10 sheets of plain paper and 5 sheets of coated paper). However, it is also possible to select a table while considering the order and the number of sheets received.

[0057] <Explanation of the time determination flow> Previously, we demonstrated an example where acquiring information about the recording material before starting a print job suppresses changes in the target temperature of the heating rotating body of the fixing unit 117 during image formation. However, the time from when the start button 602 is pressed until image formation begins is set to be short in order to increase productivity (number of printed sheets per unit time). Therefore, if it takes a long time to acquire the information about the recording material, for example, if the information about the recording material is heavy, image formation will start only after the acquisition of the information about the recording material is complete. This could lead to a delay until the first recording material for which image formation is complete is ejected, potentially reducing productivity.

[0058] Let's explain specifically what happens when the information on the recording material is heavy. When reading an image, it is necessary to prepare image formation information on a page-by-page basis. This involves RIP (Raster Image Processor) processing, which converts the print control information written in the page description language into bitmap information. The processing time for these RIP processes varies depending on the amount of information written in the page description language, the number and complexity of vector image information to be converted into bitmap information on a single page, and the number of objects to be converted from bitmap data of different formats and resolutions to match the printer engine. If this processing time becomes large, productivity may decrease.

[0059] Therefore, in this embodiment, information about the recording material is acquired before the start of the print job, but a time limit is set for acquiring this information. This makes it possible to print without significantly reducing productivity.

[0060] It is also conceivable to set a fixed time for acquiring information on the recording material, regardless of the job type. However, in this embodiment, the fixed time is varied depending on the job. If it is set to a fixed value, there may be cases where there is insufficient information on the recording material acquired before image formation, making it impossible to select the optimal fixing temperature table. This is the case with saddle-stitched or glued bound books. This is because, as mentioned above, due to the post-processing operations, the processing order of the pages is reversed, and the cover is printed last. In particular, the cover of bound books often uses a different type of paper than the main text, such as coated paper, to improve the appearance of the final product, so there is a high possibility of jobs containing mixed paper types. Information on the recording material is acquired according to the printing order. As a result, the fixed time may be reached before information on paper with a large basis weight or coated paper is acquired, and the CPU 901 will control the temperature of the heating rotating body of the fixing unit 117 without considering the information on these recording materials. Consequently, the frequency and amount of temperature changes of the heating rotating body of the fixing unit 117 will increase, resulting in a decrease in productivity. For jobs where the printing order might result in heavier paper weights or coated paper being used towards the end of the process, it may be advisable to extend the scheduled printing time.

[0061] Figure 7 illustrates the flow for determining the predetermined time. The CPU 901 waits for the start key 602 to be pressed (NO in S101), and starts the job when it is pressed (YES in S101). The CPU 901 obtains the type of job to be used for the image forming operation (S102). Then, the CPU 901 determines from the job type obtained in S102 whether saddle stitching or center folding is specified as the post-processing (S103).

[0062] If saddle stitching or center folding is specified (YES in S103), the CPU 901 sets the predetermined time to 20 seconds (S104). If saddle stitching or center folding is not specified (NO in S103), the CPU 901 sets the predetermined time to 2 seconds (S105). Here, the predetermined time for saddle stitching or center folding is set to 20 seconds because in this embodiment, the maximum number of pages for saddle stitching or center folding is fixed at 25, and even if the cover information is received last due to the reversed page order, this is considered sufficient time. In other cases, since the page order is correct, it is set to 2 seconds because the paper information for the cover and body can be obtained with at least two pages of information. Thus, the predetermined time can be determined by the engine configuration.

[0063] Next, CPU901 starts a timer to measure a predetermined time (S106).

[0064] Next, the CPU 901 determines whether the timer has reached the predetermined time determined in S104 and S105. If the timer has not reached the predetermined time (YES in S107), the process proceeds to S108. If the timer has reached the predetermined time (NO in S107), the process proceeds to S111. Next, the CPU 901 determines whether it has received information about the recording material. If it has not received information about the recording material (NO in S108), the process returns to S107. If it has received information about the recording material (YES in S108), the CPU 901 stores the information about the recording material in the RAM 903 (S109). Next, if the CPU 901 has stored information about 15 or more recording materials (YES in S110), the process proceeds to S111. If it has stored information about fewer than 15 recording materials (NO in S110), the process returns to S107. Each time the process returns to S107, the information about the recording material to be acquired is changed according to the printing order.

[0065] Next, based on the recording material information stored in S109, the system selects the table with the smallest temperature change from the fixing temperature tables shown in Figure 6 (S111). In S111, if the system came from S107, that is, if the number of recording materials acquired by the CPU 901 is less than a predetermined number, the fixing temperature table is determined based on the recording material information stored up to the predetermined time elapsed. On the other hand, if the system came from S110, that is, if the number of recording materials acquired by the CPU 901 is the predetermined number, the fixing temperature table is determined based on the information of 15 recording materials that have been stored.

[0066] Subsequently, CPU 901 performs image formation using the fixing temperature for the paper calculated from the fixing temperature table determined in S111 (S112). Then, if there is a next page (YES in S113), it returns to S112; if there is no next page (YES in S113), it terminates the job.

[0067] Here, the predetermined number of pages is uniformly set to 15, but the number may be changed depending on the engine configuration. The predetermined number of pages may also be changed depending on the type of job. In this embodiment, saddle-stitched binding was used as an example, but jobs where the processing order of pages is reversed, similar to saddle-stitched binding (for example, perfect binding which creates a finished product by gluing), may be handled in the same way.

[0068] For example, in the previous example of a job involving 10 sheets of plain paper and 5 sheets of coated paper, if information on the predetermined number of 15 recording materials is acquired within the predetermined time, fixing temperature table 3, which has a small change in fixing temperature, will be set as the target temperature. However, let's consider the case where information on the predetermined number of recording materials cannot be acquired within the predetermined time. If information on 8 recording materials is acquired within the predetermined time, the CPU 901 will set the fixing temperature table based on the information on 1 to 8 sheets of plain paper. The fixing temperature table setting of the image forming apparatus is set to fixing temperature table 2 by default. Fixing temperature table 2 is set and image forming begins. Therefore, because a predetermined time is set, the fixing temperature may differ depending on whether or not information on the predetermined number of recording materials can be acquired within the predetermined time.

[0069] Furthermore, in the case of a print job consisting of 8 sheets of plain paper and 7 sheets of coated paper, if information on the predetermined number of 15 recording materials is acquired within the predetermined time, the fixing temperature table 3, which requires the least change in fixing temperature, is set as the target temperature. However, consider the case where information on only 8 recording materials can be acquired within the predetermined time, but all the paper types included in the print job are present in those 8 sheets. In this case, the fixing temperature table set will be the same whether or not information on the predetermined number of recording materials can be acquired within the predetermined time, thus suppressing the decrease in productivity due to temperature changes.

[0070] Conventionally, if it took a long time to acquire information from the recording material after the print job started, the start of image formation would be delayed. However, in this embodiment, a predetermined time is set for acquiring information from the recording material after the print job starts. As a result, when the predetermined time is reached, image formation is forcibly started. Therefore, the time from when the image-formed recording material is first ejected from the image forming apparatus is shortened.

[0071] Furthermore, in this embodiment, for the sake of simplicity, the image formation operation is said to start after the fixing temperature table has been determined. However, preparatory operations for entering the image formation operation (for example, rotation of the photosensitive drum 111 and setting of various high-voltage sequences) may be performed in parallel while the information of the recording material is being acquired. Doing so will shorten the time from when the print job starts until the recording material with completed image formation is ejected.

[0072] In this embodiment, an example was described in which a predetermined time is determined based on the type of job when a job is received. However, this is not limited to when a job is received; the predetermined time may be determined based on paper information when information about the recording material is acquired. The same applies to the start of measurement of the predetermined time. In this embodiment, the start of measurement of the predetermined time was set when the start button 602 is pressed or when the predetermined time is set, but it may also be set when the CPU 901 receives a print job.

[0073] As explained above, by allocating a predetermined time for acquiring information from the recording material before image formation begins, it becomes possible to suppress a decrease in productivity and enable printing even when image preparation takes a long time.

[0074] Furthermore, by extending the predetermined time depending on the type of job, it becomes possible to shorten the time required to complete the deliverables.

[0075] Furthermore, while the timeout period is fixed to the job content, it is also possible to configure the system so that the timeout period can be arbitrarily changed by providing a screen for setting it on the control panel or printer driver. This allows users who frequently mix different types of print content within the main body of a document, rather than mixing them between the cover and the body, to increase the timeout period, while users who only print one type of paper can decrease the timeout period. This effectively shortens the waiting time until the print job is completed, thereby increasing user productivity. [Explanation of symbols]

[0076] 10 Image forming apparatus 117 Fixing section 500 Finisher 523 Binding Pass 580 Binding Processing Tray 820 saddle-stitch stapler 850 Binding Tray 901 CPU 902 ROM 903 RAM

Claims

1. A heating rotating body that applies heat to the recording material and A pressurizing rotating body that pressurizes the aforementioned heating rotating body, The heating rotating body, together with the pressurizing rotating body, forms a nip portion and applies heat and pressure to the recording material carrying the toner image at the nip portion, thereby fixing the toner image to the recording material. An image forming apparatus that forms an image on a recording material by fixing the aforementioned toner image onto the recording material, An acquisition unit that acquires basis weight information of the recording material, A temperature control unit that controls the temperature of the heating rotating body based on the basis weight information, If, after a print start signal for a job to form an image on a predetermined number of recording materials is input, the basis weight information for a predetermined number of materials can be acquired within a predetermined time, the temperature control unit controls the temperature of the heating rotating body based on the basis weight information of the predetermined number of recording materials. If the predetermined number of basis weight information sheets cannot be obtained within the predetermined time after the print start signal for the job is input, the temperature control unit controls the temperature of the heating rotating body based on the basis weight information of fewer than the predetermined number of recording materials. An image forming apparatus characterized by the following features.

2. The image forming apparatus has a processing device capable of performing bookbinding, When the aforementioned binding process is performed, the predetermined time is longer compared to when the binding process is not performed. The image forming apparatus according to feature 1.

3. The image forming apparatus according to claim 1, characterized in that the fixing temperature of the heating rotating body to the recording material is the same whether or not the basis weight information for a predetermined number of sheets can be obtained within a predetermined time after a print start signal for a job to form an image on a predetermined number of recording materials is input.

4. The image forming apparatus according to claim 1, characterized in that the predetermined time can be changed arbitrarily.

Images