Image formation device

Abstract

To reduce power consumption during adhesive processing.SOLUTION: An image formation device includes: image formation means for forming an image including an adhesive image made of a powder adhesive on a sheet being transported; adhesive means to which a plurality of sheets on which the image has been formed by the image formation means are transported in sequence, the adhesive means heating the plurality of sheets to adhere the plurality of sheets with the adhesive image formed on the plurality of sheets; and control means for evaluating the temperature of the plurality of sheets transported to the adhesive means and controlling the amount of heat imparted to the plurality of sheets by the adhesive means heating the plurality of sheets based on the evaluated temperature.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an image forming apparatus using a powder adhesive.

Background Art

[0002] As an image forming apparatus, after forming an image on a sheet, an apparatus that performs a stapling process on a plurality of sheets on which the image is formed to create a booklet is used. In the stapling process, a metal needle is used. On the other hand, Patent Document 1 discloses a configuration for creating a booklet without using a metal needle by adhering sheets to each other with a powder adhesive. According to Patent Document 1, toner is used as the powder adhesive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to adhere sheets to each other with a powder adhesive, it is necessary to heat the sheet to which the powder adhesive is attached, and the power consumption becomes larger compared to the stapling process.

[0005] The present invention provides a technique for reducing power consumption in the adhesion process.

Means for Solving the Problems

[0006] According to one aspect of the present invention, an image forming apparatus includes: an image forming unit that forms an image including an adhesive image by a powder adhesive on a conveyed sheet; an adhesion unit to which a plurality of sheets on which the image has been formed by the image forming unit are sequentially conveyed, the adhesion unit heating the plurality of sheets to adhere the plurality of sheets by the adhesive images formed on the plurality of sheets; and a control unit that evaluates the temperature of the plurality of sheets conveyed to the adhesion unit and controls the amount of heat applied to the plurality of sheets by the adhesion unit heating the plurality of sheets based on the evaluated temperature.

Advantages of the Invention

[0007] According to the present invention, the power consumption in the adhesion process can be reduced.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] <First Embodiment> FIG. 1 is a configuration diagram of an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 includes forming units 7Y, 7M, 7C, and 7K that store yellow, magenta, cyan, and black toners, respectively, and form yellow, magenta, cyan, and black toner images. In the following description, it is assumed that black toner is used as a powder adhesive. Regarding the black toner, it can be configured to be used only for adhering sheets, or can be configured to be used both for adhering sheets and for forming a black toner image. When the black toner is used only for adhering sheets, the black color in the image formed on the sheet can be formed by overlapping yellow, magenta, and cyan toners. Note that the color of the toner used as the powder adhesive may be different from black. Further, the number of colors of the toner used as the powder adhesive can be two or more. Further, when the forming unit 7K is used only for adhering sheets, the forming unit 7K can be configured to store a transparent or arbitrary color powder adhesive instead of black toner. Further, a fifth forming unit used for adhering sheets can be provided, and the forming unit can be configured to store a transparent or arbitrary color powder adhesive.

[0011] The configurations of the forming units 7Y, 7M, 7C, and 7K are the same, and each has a photoreceptor 71, a charging roller 72, a developing roller 73, and a primary transfer roller 74. In the following description, when the forming units 7Y, 7M, 7C, and 7K are collectively referred to, they are denoted as forming unit 7. The photoreceptor 71 is rotationally driven in the clockwise direction in the figure during image formation. The charging roller 72 charges the photoreceptor 71 to a uniform potential. The scanner unit 2 forms an electrostatic latent image on each photoreceptor 71 by exposing each photoreceptor 71. Note that the electrostatic latent image includes an electrostatic latent image for adhesion and an electrostatic latent image not for adhesion. The developing roller 73 forms an image of toner (or powder adhesive) on the photoreceptor 71 by developing the electrostatic latent image of the photoreceptor 71 with toner (or powder adhesive). The image formed on the photoreceptor 71 by development includes an image for adhesion and an image not for adhesion. In the following description, the image for adhesion is denoted as an adhesive image.

[0012] The primary transfer roller 74 transfers the image formed on each photoreceptor 71 to the intermediate transfer member 3 that is rotationally driven in the counterclockwise direction in the figure. Due to the rotation of the intermediate transfer member 3, the image transferred to the intermediate transfer member 3 is conveyed to the position facing the secondary transfer roller 5. The secondary transfer roller 5 transfers the image of the intermediate transfer member 3 to the sheet P that has been conveyed along the conveyance path from the cassette 8 or the tray 20.

[0013] The fixing device 6 performs a fixing process of fixing the image on the sheet P by heating and pressing the sheet P on which the image has been transferred. The fixing device 6 includes a heating film 6b that is a heating member, a ceramic heater 6a that is a heat source of the heating film 6b, and a pressure roller 6c that is a pressure member. Further, the fixing device 6 has a temperature sensor, for example, a radiation thermometer, that measures the surface temperature of the heating film 6b (not shown). The sheet P is heated by the heating film 6b and pressed by the pressure roller 6c while passing through the nip region between the heating film 6b and the pressure roller 6c. In the following description, the nip region between the heating film 6b and the pressure roller 6c of the fixing device 6 is simply denoted as "the nip region of the fixing device 6".

[0014] The forming units 7Y, 7M, 7C, and 7K, the scanner unit 2, the intermediate transfer member 3, the secondary transfer roller 5, and the fixing unit 6 constitute an image forming unit that forms an image on the conveyed sheet P.

[0015] When forming an image only on one side (the front surface) of the sheet P, the sheet P that has passed through the fixing unit 6 is conveyed by the flapper 33 toward the intermediate conveyance unit 200. When forming images on both sides of the sheet P, the sheet P on which an image has been formed on the first side (the front surface) is conveyed by the flapper 33 toward the reversing roller 35 after passing through the fixing unit 6, and then is conveyed by the reversing roller 35 toward the duplex conveyance path 36. The sheet P conveyed toward the duplex conveyance path 36 is conveyed again to the opposing position of the secondary transfer roller 5 to form an image on the second side (the back surface). The sheet P on which images have been formed on both sides is conveyed by the flapper 33 toward the intermediate conveyance unit 200 after passing through the fixing unit 6.

[0016] The sheet P conveyed to the intermediate conveyance unit 200 is conveyed along the conveyance path 46 to the post-processing device 300. In the case of a sheet P on which no adhesion process is performed, the sheet P is discharged to the discharge tray 25 by the discharge roller 24. When performing the adhesion process on the sheet P, after the rear end of the sheet P passes the position of the flapper 23, the discharge roller 24 is rotated in the opposite direction to that until then, so as to convey the sheet P toward the thermocompression bonding unit 51. At that time, the flapper 23 is set in a direction to guide the sheet P toward the thermocompression bonding unit 51.

[0017] The thermocompression bonding unit 51 functions as an adhesion part that performs an adhesion process on the sheet P. A plurality of sheets P to be subjected to the adhesion process are sequentially stacked on the intermediate stacking part 42 of the thermocompression bonding unit 51. Alignment processes are performed on the plurality of sheets P stacked on the intermediate stacking part 42 by the vertical alignment reference plate 39 and the horizontal alignment reference plate 43 (Figure 2). After the alignment process, an adhesion process is performed on the plurality of sheets P stacked on the intermediate stacking part 42.

[0018] FIG. 2 is a cross-sectional view of the thermocompression bonding unit 51 when viewed from the direction opposite to the conveyance direction of the sheet P from the vertical alignment reference plate 39 of FIG. 1. The heating plate 502 made of aluminum is heated by the ceramic heater 501 which is a heat source. The ceramic heater 501 is supported by the heater support 503 made of resin. The pressing lever 504 presses down the heating plate 502 via the metal stay 505, thereby heating and pressing the sheet P loaded on the intermediate loading section 42 by the heating plate 502. In addition, a receiving member 506 for stably receiving the pressing force is provided in the region on the intermediate loading section 42 side corresponding to the region of the sheet P pressed by the heating plate 502. The receiving member 506 is made of, for example, silicon rubber. The adhesive image is provided within the region of the sheet P heated and pressed by the heating plate 502.

[0019] FIG. 3(A) shows the adhesive image Tk formed on the sheet P. As shown in FIG. 3(A), the adhesive image Tk is formed along one of the two sides of the sheet P parallel to the conveyance direction of the sheet P. Thereby, a bound booklet can be formed. Further, as shown in FIG. 3(B), the adhesive image Tk can be formed along a partial section of one of the two sides of the sheet P parallel to the conveyance direction of the sheet P. Thereby, a corner-bound booklet can be created. In the present embodiment, as shown in FIG. 3(C), the adhesive image Tk is formed only on one surface of the sheet P loaded on the intermediate loading section 42, for example, the first surface. Therefore, as shown in FIG. 3(C), the adhesive image Tk is not formed on the sheet P located at one of the two ends of the booklet. Note that a configuration in which the adhesive image Tk is formed on all the surfaces to be adhered to other sheets P may also be acceptable.

[0020] Returning to FIG. 1, after the completion of the adhesion process by the thermocompression bonding unit 51, the booklet composed of a plurality of adhered sheets P is pushed out toward the discharge roller 38 by a bundle discharge guide (not shown) and discharged to the discharge tray 37 by the discharge roller 38.

[0021] The control unit 100 includes a volatile and / or non-volatile memory and one or more processors. The one or more processors control the entire image forming apparatus 1 by executing a control program stored in the memory. For example, the control unit 100 controls the power supplied to the ceramic heater 6a so that the surface temperature of the heating film 6b measured by the temperature sensor of the fixing unit 6 becomes the target temperature. Further, the control unit 100 controls the adhesion process by the thermocompression bonding unit 51. Also, in the adhesion process, the control unit 100 controls the heating temperature and heating time by the heating plate 502. In addition to the control program, the memory stores various control data used in the control of the image forming apparatus 1. The temperature sensor 60 is provided at a position not affected by the heat generation of the fixing unit 6, detects the temperature around the image forming apparatus 1 (hereinafter referred to as the ambient temperature), and outputs a signal indicating the detected ambient temperature to the control unit 100. The operation unit 50 provides an input / output interface for the user.

[0022] In this embodiment, the adhesion process by the thermocompression bonding unit 51 is performed in units of a predetermined number N sheets (N is an integer of 2 or more). That is, when creating one booklet with M sheets (M is an integer of 2 or more) that is N sheets or less, when M sheets of the sheet P are loaded on the intermediate loading unit 42, the thermocompression bonding unit 51 performs the adhesion process to create one booklet. On the other hand, when M is more than N sheets, the thermocompression bonding unit 51 performs the adhesion process each time N sheets of the sheet P are newly loaded on the intermediate loading unit 42 and when the last sheet P of the M sheets constituting one booklet is loaded on the intermediate loading unit 42. In the following description, as an example, N is set to 5. Therefore, when M = 12, when the 1st to 5th sheets P are loaded on the intermediate loading unit 42, the thermocompression bonding unit 51 performs the first adhesion process. Subsequently, when the 6th to 10th sheets P are loaded on the 5th sheet P that was the target of the previous adhesion process, the thermocompression bonding unit 51 performs the second adhesion process. Further, when the 11th and 12th sheets P are loaded on the 10th sheet P, the thermocompression bonding unit 51 performs the third adhesion process. In the following description, the 1 to N sheets (5 sheets in this example) of the sheet that is the target of the adhesion process are referred to as the sheet bundle to be processed. For example, when creating one booklet with 12 sheets, the 1st to 5th sheets P are one sheet bundle to be processed, the 6th to 10th sheets P are one sheet bundle to be processed, and the 11th and 12th sheets are one sheet bundle to be processed.

[0023] In this embodiment, in order to reduce the power consumption in the adhesion process, the amount of heat applied by the heating plate 502 to the sheet P in the adhesion process is appropriately controlled. As methods for controlling the amount of heat applied by the heating plate 502 to the sheet P, there are a method of controlling the heating temperature by the heating plate 502, a method of controlling the heating time by the heating plate 502, and a method of controlling both the heating temperature and the heating time by the heating plate 502. In the following description, as an example, it is assumed that the heating time by the heating plate 502 is fixed at 2 seconds, and the amount of heat applied to the sheet P is controlled by controlling the heating temperature. Note that when the heating temperature is constant, as the heating time becomes longer, the amount of heat applied to the sheet P increases. Similarly, when the heating time is constant, as the heating temperature increases, the amount of heat applied to the sheet P increases.

[0024] Subsequently, for the purpose of understanding the embodiment, the results of each experiment conducted by the inventor will be described. In the experiments described below, as the sheet P, RedLabelPresentation (A4 size) manufactured by Canon Inc. was used. Also, in the following description, when distinguishing a plurality of sheets P loaded in the intermediate loading unit 42, the order in which they were conveyed to the intermediate loading unit 42 is used. That is, the first sheet P is the sheet P that was first conveyed to the intermediate loading unit 42, that is, the sheet P that is in contact with the receiving member 506 in FIG. 2.

[0025] (Relationship between sheet temperature and adhesiveness during adhesion process) An experiment was conducted on the relationship between the temperature of the sheet P during the adhesion process and the adhesiveness. In the experiment, five sheets P were loaded in the intermediate loading unit 42 and immediately the adhesion process was performed by the thermocompression unit 51 while changing the heating temperature by the heating plate 502 and the temperature of the sheet P loaded in the intermediate loading unit 42. As described above, the heating time in the thermocompression unit 51 was set to 2 seconds.

[0026] After the subsequent process, as shown in Fig. 4(A), a portion with a length We = 20 mm in the conveyance direction and a width Le = 50 mm in the width direction orthogonal to the conveyance direction was cut out from the booklet formed by the adhesion process as the test piece E. Then, while holding the first sheet P of the test piece E, the second to fifth sheets P were pulled upward, and the strength when the first and second sheets of the test piece peeled off was measured with a digital force gauge as the adhesion strength. As the digital force gauge, FGP-2 manufactured by Nidec-Shimpo Corporation was used. The reason for taking the strength when the first and second sheets of the test piece peel off as the adhesion strength is that among the four adhesive images Tk for adhering the five sheets P, the adhesive image Tk between the first and second sheets is the farthest from the heating plate 502. That is, the temperature of the adhesive image Tk between the first and second sheets is the most difficult to rise.

[0027] Regarding the adhesion strength, considering the actual use, a value of 0.5 N / cm or more per unit distance in the conveyance direction of the test piece E was regarded as passing. Fig. 4(B) shows the experimental results. The "temperature before treatment" in Fig. 4(B) is the temperature of the sheet P before the adhesion process, and the "heating temperature" indicates the heating temperature at which the adhesion strength becomes 0.5 N / cm or more. According to Fig. 4(B), as the temperature before treatment rises, the heating temperature required to maintain the adhesion strength decreases. More specifically, according to the experimental results in Fig. 4(B), the relationship between the heating temperature Tg and the temperature Ta before treatment is expressed by the following Equation 1. Tg = -0.6Ta + 230 (Equation 1) In this way, the higher the temperature of the sheet P before the adhesion process, the lower the temperature of the heating plate 502 can be.

[0028] (Estimation of the pressure roller temperature during fixing) In this embodiment, the temperature of the pressure roller 6c during the fixing process of the sheet P is estimated and used as the evaluation value of the temperature of the sheet P before processing. First, a method for estimating the temperature of the pressure roller 6c will be described. FIG. 5 shows a heat conduction model for estimating the temperature of the pressure roller 6c. Note that FIG. 5(A) is a model when the fixing process of the sheet P is not being performed, and FIG. 5(B) is a model when the fixing process of the sheet P is being performed. In the following description, the temperatures of the pressure roller 6c and the heating film 6b at time t are denoted as Tr(t) and Tf(t), respectively.

[0029] The temperature Tr(t) of the pressure roller 6c at time t when the fixing process is not being performed is estimated based on the following difference equation. {Tr(t) - Tr(t - Δt)} / Δt = A1{Tf(t - Δt) - Tr(t - Δt)} (Equation 2) In Equation 2, Δt is the estimation period, for example, 20 ms. The coefficient A1 is a positive value and is obtained through experiments. From Equation 2, when the temperature of the heating film 6b at time (t - Δt) is higher than the temperature of the pressure roller 6c, the temperature of the pressure roller 6c at time t rises from time (t - Δt). While the fixing process is not being performed, the control unit 100 can estimate the temperature Tt(t) of the pressure roller 6c based on the temperature of the heating film 6b obtained from the temperature sensor of the fixing device 6. Note that the initial temperature when starting the estimation of the temperature Tr(t) of the pressure roller 6c can be, for example, a predetermined value or the ambient temperature measured by the temperature sensor 60.

[0030] The temperature Tr(t) of the pressure roller 6c at time t when the fixing process is being performed is estimated based on the following difference equation. {Tr(t) - Tr(t - Δt)} / Δt = A2{Tr(t - Δt) - Tp} (Equation 3) In Equation 3, Tp is the temperature of the sheet P. In this example, it is set to a predetermined value, for example, 23°C. Note that the temperature Tp of the sheet P can also be the ambient temperature measured by the temperature sensor 60. The coefficient A2 is a negative value and is determined by experiments. From Equation 3, when the temperature of the pressure roller 6c at time (t - Δt) is higher than the temperature of the sheet P, the temperature of the pressure roller 6c at time t decreases from time (t - Δt). When the fixing process is started, the control unit 100 estimates the temperature Tr(t) of the pressure roller 6c based on Equation 3. Note that the temperature Tr(t) of the pressure roller 6c when the fixing process is started is based on Equation 2.

[0031] When starting image formation by a print job, the fuser 6 performs a startup process including starting the heating of the heating film 6b. In the startup process, the temperature of the pressure roller 6c rises due to the heat of the heating film 6b. During the fixing process, since the sheet P takes away the heat of the pressure roller 6c, the temperature of the pressure roller 6c decreases. However, it takes about one hour for the temperature of the pressure roller 6c warmed by the printing process to drop to near room temperature. Therefore, when repeatedly creating booklets in a relatively short time, the temperature of the pressure roller 6c gradually rises.

[0032] (Relationship between the temperature of the pressure roller 6c and the pre-treatment temperature) An experiment was conducted on the relationship between the temperature Tr of the pressure roller 6c estimated using the above Equations 2 and 3 and the pre-treatment temperature Ta. First, a total of 4 experiments were conducted in which booklets made of 5 sheets of sheet P were created 3 sets every 5 seconds. At that time, the temperature of the sheet P conveyed to the thermocompression bonding unit 51 was measured with a non-contact temperature sensor. Note that at the start of each time, the temperature of the pressure roller 6c was set to 23°C, which is the room temperature. Also, the periods of the startup process of the fuser 6 in the first, second, third, and fourth times (hereinafter referred to as the startup time) were set to 5 seconds, 7.5 seconds, 10 seconds, and 20 seconds, respectively.

[0033] Figure 6 shows the above experimental results. From Figure 6, it can be seen that there is a positive correlation between the estimated temperature Tr of the pressure roller and the temperature Ta of the sheet P before treatment. That is, the higher the estimated temperature Tr of the pressure roller, the higher the temperature Ta before treatment. In the results of Figure 6, the relationship between the temperature Tr of the pressure roller and the temperature Ta before treatment is as follows. Ta = 0.0789Tr + 45.9 (Equation 4)

[0034] (Adhesion strength between multiple sheets) As described with respect to Figure 4, in this embodiment, the strength when the first sheet P and the second sheet P are peeled off is defined as the adhesion strength. An experiment was conducted to verify the validity of this. First, as shown in Figure 7(A), the adhesive image that adheres the nth sheet P (n is an integer from 1 to 4) and the (n + 1)th sheet P is denoted as Tn(n + 1). The initial temperature of each sheet P was set to 23°C, and the sheet P was heated by a heating plate 502 at 200°C for 2 seconds, and the temperature of the adhesive image Tn(n + 1) was measured. Figure 7(B) shows the experimental results. From Figure 7(B), the temperature of the adhesive image T12 that adheres the first sheet P and the second sheet P is the lowest.

[0035] (Temperature control of the thermocompression unit 51) Based on the above experiments, in this embodiment, the temperature before adhesion (pre-treatment temperature) of N or fewer (in this example, 5) sheets constituting the sheet bundle to be processed is evaluated, and the heating temperature in the adhesion process is controlled based on the evaluated temperature. Here, as the pre-treatment temperature of the sheet bundle to be processed, among the N or fewer sheets constituting one sheet bundle to be processed, the pre-treatment temperature of the sheet P (hereinafter referred to as the reference sheet) located at the position farthest from the heating plate 502 is used. In this example, the reference sheet is the sheet P that is conveyed to the thermocompression unit 51 first among the N or fewer sheets constituting one sheet bundle to be processed. Further, in this embodiment, the pre-treatment temperature of the reference sheet is evaluated based on the temperature Tr of the pressure roller 6c during the fixing process of the reference sheet. Note that the temperature Tr of the pressure roller 6c used as the evaluation value of the pre-treatment temperature of the reference sheet can be the temperature Tr of the pressure roller 6c at a predetermined timing during the fixing process of the reference sheet. As an example, the predetermined timing can be the timing when the fixing process of the reference sheet is completed, that is, the timing when the trailing end of the reference sheet has passed through the nip region of the fixing device 6. Alternatively, the temperature Tr of the pressure roller 6c used as the evaluation value of the pre-treatment temperature of the reference sheet can be a statistical value obtained based on the temperature Tr of the pressure roller 6c during the fixing process of the reference sheet, for example, an average value.

[0036] FIG. 8 is a flowchart regarding the fixing process according to the present embodiment. The process in FIG. 8 starts with the reception of a printing job involving an adhesion process. In S10, the control unit 100 forms an image on the sheet P, and in S11, the sheet P on which the image has been formed is conveyed to the thermocompression bonding unit 51. In S12, the control unit 100 determines whether the execution conditions for the adhesion process are satisfied. In the present embodiment, the execution conditions for the adhesion process are satisfied when five new sheets P are conveyed to the thermocompression bonding unit 51. In this case, the number of sheets in the sheet bundle to be processed is five. Note that even when it is the last sheet in the printing job, the execution conditions for the adhesion process are satisfied. In this case, the number of sheets in the sheet bundle to be processed can be any one of 1 to 4. If the execution conditions for the adhesion process are not satisfied, the control unit 100 repeats the process from S10. On the other hand, when the execution conditions for the adhesion process are satisfied, the control unit 100 executes the adhesion process in S13. At this time, the control unit 100 controls based on the evaluation value of the temperature before processing of the reference sheet, that is, the temperature of the heating temperature in the adhesion process, namely, the temperature of the heating plate 502. In the present embodiment, the evaluation value of the temperature before processing of the reference sheet is the temperature Tr of the pressure roller 6c during the fixing process of the reference sheet. In S14, the control unit 100 determines whether the printing job is completed. If not, the process is repeated from S10. On the other hand, when the printing job is completed, the control unit 100 ends the process in FIG. 8.

[0037] (Comparison) FIG. 9 shows a comparative example between the case where the heating temperature in the bonding process is set constant and the case where the heating temperature in the bonding process is controlled based on the content described in this embodiment. In the experiment, a total of three times were performed to create three sets of one booklet made of five sheets P every 5 seconds. Note that the temperature of the pressure roller 6c at the start of each time was set to 23° C., which is room temperature. Also, the start-up times of the fuser 6 in the first, second, and third times were set to 5 seconds, 7.5 seconds, and 10 seconds, respectively. Note that, as described above, the heating time by the heating plate 502 was set to 2 seconds. Regarding the power consumption, a wattmeter was connected to the ceramic heater 501 to measure the power consumption [W] of the thermocompression unit 51, and the calculated power consumption [W] was integrated over the heating time (2 seconds). Note that the heating temperature in the comparative example was set to 200° C.

[0038] The pressure roller temperature in FIG. 9 indicates the temperature Tr of the pressure roller 6c estimated at the timing when the fixing process of the reference sheet is completed. Also, the temperature before the process in FIG. 9 indicates the temperature before the process obtained from the temperature Tr of the pressure roller 6c according to Equation 4. As shown in FIG. 9, as the temperature Tr of the pressure roller 6c increases, that is, as the evaluation result of the temperature before the process increases, the control unit 100 decreases the heating temperature. Therefore, the power consumption in the bonding process can be reduced.

[0039] Note that the control unit 100 may be configured to store in advance determination information for determining the heating temperature based on, for example, the temperature of the reference sheet before processing. The determination information in this case may be, for example, information indicating the relationship between the temperature before processing and the heating temperature as shown in Equation 1. Based on the estimated temperature Tr of the pressure roller 6c, the control unit 100 obtains the temperature before processing according to, for example, Equation 4, and sets the heating temperature by referring to the determination information based on the obtained temperature before processing. Alternatively, the control unit 100 may be configured to store in advance determination information for determining the heating temperature based on the temperature Tr of the pressure roller 6c. The determination information in this case indicates the relationship between the temperature Tr of the pressure roller 6c and the heating temperature, and can be obtained based on, for example, Equation 1 and Equation 4. The control unit 100 sets the heating temperature by referring to the determination information based on the estimated temperature Tr of the pressure roller 6c. Note that the temperature of the reference sheet may decrease between when the reference sheet is conveyed to the thermocompression bonding unit 51 and when the bonding process is performed. Therefore, the determination information may be created in consideration of this temperature decrease of the reference sheet.

[0040] Note that as the start-up time of the fixing device 6 becomes longer, the temperature of the fixing roller 6c becomes higher. Therefore, it is also possible to adopt a configuration in which the heating temperature is lowered as the start-up time becomes longer. Further, the temperature Tr of the fixing roller 6c when performing the fixing process on the reference sheet and the temperature of the reference sheet conveyed to the thermocompression bonding unit 51 are measured by a non-contact temperature sensor, and the heating temperature of the bonding process is controlled based on the measured values.

[0041] Furthermore, instead of measuring the temperature of the reference sheet conveyed to the thermocompression bonding unit 51, it is also possible to adopt a configuration in which the temperature of the reference sheet after the fixing process by the fixing device 6 is measured between when it is conveyed from the fixing device 6 to the thermocompression bonding unit 51. Similarly, instead of estimating the temperature of the reference sheet conveyed to the thermocompression bonding unit 51 by Equation 1 or the like, it is also possible to adopt a configuration in which the temperature of the reference sheet conveyed at a predetermined position between the fixing device 6 and the thermocompression bonding unit 51 is estimated. This is based on the fact that the higher the temperature of the sheet P at any position between the fixing device 6 and the thermocompression bonding unit 51, the higher the temperature of the sheet P before processing.

[0042] Furthermore, in the present embodiment, the pre-treatment temperature of the first sheet P in the sheet bundle to be processed is used as the pre-treatment temperature of the sheet bundle to be processed, but a configuration may be adopted in which the pre-treatment temperature of other sheets P in the sheet bundle to be processed is used. For example, when the receiving member 506 is preheated by the heating plate 502 to warm the first sheet P in a state where there is no sheet P in the thermocompression unit 51, the temperature of the adhesive image T23 may be lower than that of the adhesive image T12 in FIG. 7(A). In such a case, the second sheet P can be used as the reference sheet. That is, the reference sheet can be determined according to the configuration of the thermocompression unit 51. Furthermore, when considering the pre-treatment temperature of each sheet P included in the sheet bundle to be processed, a value obtained based on the pre-treatment temperature of each sheet P included in the sheet bundle to be processed can be used as the pre-treatment temperature of the sheet bundle to be processed.

[0043] Note that although the temperature Tr of the pressure roller 6c is estimated according to the heat conduction model shown in FIG. 5, the present embodiment is not limited to estimating the temperature Tr of the pressure roller 6c according to the heat conduction model shown in FIG. 5, and any heat conduction model can be used.

[0044] <Second Embodiment> Subsequently, the differences between the second embodiment and the first embodiment will be mainly described. In the first embodiment, the temperature Tr of the pressure roller 6c is used as the evaluation value of the pre-treatment temperature. In the present embodiment, in addition to the temperature Tr of the pressure roller 6c, the temperature Tf of the heating film 6b is also used.

[0045] The control unit 100 controls the temperature Tf of the heating film 6b according to the type of the sheet P, the amount of toner loaded on the sheet P, and the like. When the temperature Tf of the heating film 6b changes, the amount of heat received by the sheet P from the heating film 6b changes when the sheet P passes through the fixing device 6, and thus the temperature of the sheet P also changes. FIG. 10 shows the results of an experiment in which the pre-treatment temperature was measured while changing the temperature of the heating film 6b. In the experiment, a total of 4 experiments were conducted to create 3 sets of booklets made of 5 sheets P every 5 seconds. At the start of each experiment, the temperature of the pressure roller 6c was set to 23°C, which is room temperature. Also, the temperatures of the heating film 6b in the first, second, third, and fourth experiments were set to 150°C, 160°C, 170°C, and 180°C, respectively. Other conditions were the same for each experiment.

[0046] FIG. 10(A) shows the relationship between the estimated temperature Tr of the pressure roller and the pre-treatment temperature at the timing when the fixing process of the reference sheet is completed. FIG. 10(B) shows the relationship between the temperature Tf of the heating film and the pre-treatment temperature at the timing when the fixing process of the reference sheet is completed. From the results of FIGS. 10(A) and 10(B), the pre-treatment temperature Ta is obtained based on the following Equation 5. Ta = 0.084Tr + 0.154Tf + 17.8 (Equation 5)

[0047] The flowchart regarding the fixing process according to the present embodiment is the same as FIG. 8. However, the evaluation value of the pre-treatment temperature of the reference sheet in S13 is the temperature Tr of the pressure roller 6c and the temperature Tf of the heating film 6b. The temperature of the heating film 6b used as the evaluation value of the pre-treatment temperature of the reference sheet is the temperature Tr of the heating film 6b at a predetermined timing during the fixing process of the reference sheet. As an example, the predetermined timing can be the timing when the fixing process of the reference sheet is completed, that is, the timing when the trailing edge of the reference sheet exits the nip region of the fixing device 6. Alternatively, the temperature of the heating film 6b used as the evaluation value of the pre-treatment temperature of the reference sheet can be a statistical value, for example, an average value, obtained based on the temperature of the heating film 6b during the fixing process of the reference sheet.

[0048] In this embodiment, even if the temperature of the heating film 6b is changed, the pre-treatment temperature can be accurately estimated, and thus the amount of heat in the adhesion treatment can be appropriately controlled. Therefore, the power consumption in the adhesion treatment can be reduced.

[0049] (Comparison) FIG. 11 shows a comparative example between the case where the heating temperature of the adhesion treatment is set constant and the case where the heating temperature of the adhesion treatment is controlled according to the content described in this embodiment. In the experiment, a total of three times were performed to create three sets of one booklet made of five sheets P every 5 seconds. Note that the temperature of the pressure roller 6c at the start of each time was set to 23° C., which is room temperature. Also, the temperatures of the heating film 6b in the first, second, and third times were set to 160° C., 170° C., and 180° C., respectively. Furthermore, the rising time of the fixing device 6 each time was set to 5 seconds, and the heating time by the heating plate 502 was set to 2 seconds. Note that the heating temperature in the comparative example was set to 202° C.

[0050] The pressure roller temperature in FIG. 11 shows the temperature Tr of the pressure roller 6c estimated at the timing when the fixing process of the reference sheet is completed. Also, the heating film temperature in FIG. 11 shows the temperature of the heating film 6b at the timing when the fixing process of the reference sheet is completed. Furthermore, the pre-treatment temperature in FIG. 11 shows the pre-treatment temperature of the reference sheet obtained from the temperature Tr of the pressure roller 6c and the temperature Tf of the heating film 6b according to Equation 5. As shown in FIG. 11, the power consumption of the adhesion treatment can be reduced as compared with setting the heating temperature constant.

[0051] Note that, without using the temperature Tr of the pressure roller 6c, the higher the temperature Tf of the heating film 6b is set, the lower the heating temperature can be set. This is based on the fact that the higher the temperature Tf of the heating film 6b is set, the higher the pre-treatment temperature of the reference sheet becomes. Furthermore, also in this embodiment, the pre-treatment temperature of the sheet bundle to be processed can be set to a value based on the pre-treatment temperature of any one or more sheets P included in the sheet bundle to be processed.

[0052] <Third Embodiment> Next, the differences between the third embodiment and the first embodiment will be mainly described. In this embodiment, in addition to the temperature Tr of the pressure roller 6c, the temperature Tt of the secondary transfer roller 5, the temperature Tm of the conveyance path 46, and information on whether the operation mode of image formation is a single-sided mode or a double-sided mode are used to evaluate the pre-processing temperature. The conveyance path 46 is a conveyance path that connects the fixing device 6 and the thermocompression bonding unit 51. The single-sided mode is an operation mode in which an image is formed only on one side of the sheet P, and the double-sided mode is an operation mode in which images are formed on both sides of the sheet P. In the case of the single-sided mode, the sheet P is not conveyed through the double-sided conveyance path 36. On the other hand, in the case of the double-sided mode, the sheet P on which the fixing process of the image formed on the first side has been performed is conveyed through the double-sided conveyance path 36 for image formation on the second side, and the fixing process by the fixing device 6 is performed again.

[0053] FIG. 12 shows a heat conduction model for estimating the temperature Tt of the secondary transfer roller 5 and the temperature Tm of the conveyance path 46. Note that FIG. 12(A) is a model when the fixing process of the sheet P is not being performed, and FIG. 12(B) is a model when the fixing process of the sheet P is being performed. In FIG. 12(B), "Sheet P (before fixing)" indicates the sheet P when the image is being transferred by the secondary transfer roller 5, and "Sheet P (after fixing)" indicates the sheet P that has passed through the nip region of the fixing device 6 and the sheet P that has been sent out to the conveyance path 46. Although the timing when the sheet P passes through the conveyance path 46 and the timing when it passes through the nip region of the fixing device 6 are different, in FIG. 12(B), they are modeled as the same timing. This is because the model can be simplified by setting the same timing. Furthermore, since the temperature changes of the conveyance path 46, the intermediate transfer body 3, and the secondary transfer roller 5 are gentler compared to the pressure roller 6c, there is no problem in accuracy even if the timing when the sheet P passes is slightly deviated. However, it is also possible to model with different timings for when the sheet P passes through the conveyance path 46 and when it passes through the nip region of the fixing device 6.

[0054] When the fixing process is not being performed, the temperature Tt of the secondary transfer roller 5 and the temperature Tm of the conveyance path 46 at time t are estimated based on the following difference equations. In the following equations, the temperature of the intermediate transfer member 3 is denoted as Tb. {Tm(t) - Tm(t - Δt)} / Δt = A3{Tm(t - Δt) - Tr(t - Δt)} (Equation 6) {Tb(t) - Tb(t - Δt)} / Δt = A4{Tb(t - Δt) - Tr(t - Δt)} + A5{Tb(t - Δt) - Tt(t - Δt)} (Equation 7) {Tt(t) - Tt(t - Δt)} / Δt = A6{Tt(t - Δt) - Tr(t - Δt)} + A7{Tt(t - Δt) - Tb(t - Δt)} (Equation 8)

[0055] When the fixing process is being performed, the temperature Tt of the secondary transfer roller 5 and the temperature Tm of the conveyance path 46 at time t are estimated based on the following difference equations. In the following equations, the temperature of the sheet P (before fixing) is denoted as Tp, and the temperature of the sheet P (after fixing) is denoted as Tpe. {Tm(t) - Tm(t - Δt)} / Δt = A8{Tm(t - Δt) - Tr(t - Δt)} + A9{Tm(t - Δt) - Tpe(t - Δt)} (Equation 9) {Tpe(t) - Tpe(t - Δt)} / Δt = A10{Tpe(t - Δt) - Tr(t - Δt)} (Equation 10) {Tb(t) - Tb(t - Δt)} / Δt = A11{Tb(t - Δt) - Tr(t - Δt)} + A12{Tb(t - Δt) - Tp} (Equation 11) {Tt(t) - Tt(t - Δt)} / Δt = A13{Tt(t - Δt) - Tr(t - Δt)} + A14{Tt(t - Δt) - Tp} (Equation 12)

[0056] The coefficients A3 to A14 in the above formula are obtained by experiments. Also, the temperature Tr of the pressure roller 6c is obtained as described in the first embodiment. Here, in the present embodiment, the temperature Tp of the sheet P is set to 23°C in the single-sided mode and when forming the first side in the double-sided mode. Also, when forming the second side in the double-sided mode, the average value of the temperature Tpe of the sheet P (after fixing) during the fixing process of the image on the first side is used.

[0057] The conveyance path 46 increases in temperature due to the heat from the sheet P on which the fixing process has been performed. Also, in the case of the double-sided mode, the intermediate transfer body 3 and the secondary transfer roller 5 increase in temperature due to the heat from the sheet P on which the fixing process for the image on the first side has been performed. Note that when forming an image on the first side in the single-sided mode or the double-sided mode, the intermediate transfer body 3 and the secondary transfer roller 5 do not change in temperature due to the sheet P at a temperature similar to the ambient temperature, or the temperature decreases because heat is taken away from the sheet P.

[0058] Also, since the temperature Tm of the conveyance path 46, the temperature Tb of the intermediate transfer body 3, and the temperature Tt of the secondary transfer roller 5 change, the heat received by the sheet P when passing through these members changes, so the temperature of the sheet P changes.

[0059] FIGS. 13(A), 13(B), and 13(C) show the relationships between the temperature Tr of the pressure roller 6c, the temperature Tt of the secondary transfer roller 5, and the temperature Tm of the conveyance path 46 estimated at the timing when the fixing process of the reference sheet is completed, and the temperature of the reference sheet before processing. In the figure, 〇 indicates the temperature in the single-sided mode, and × indicates the temperature in the double-sided mode. Also, the temperatures Tr, Tt, and Tm in the double-sided mode are the values during image formation on the second side.

[0060] From the results of FIGS. 13(A) to 13(C), in the case of the single-sided mode, the pre-processing temperature Ta is obtained based on the following formula 13. Ta = 0.0778Tr + 0.154Tm + 0.0184Tt + 41.709 (Formula 13) In the case of the duplex mode, the temperature Ta before processing is obtained based on the following Equation 14. Ta = 0.0945Tr + 0.0811Tm + 0.341Tt + 39.814 (Equation 14)

[0061] The reason for not using the temperature Tb of the intermediate transfer member 3 as the evaluation value of the temperature before processing of the reference sheet is that the correlation coefficient with the temperature Tt of the secondary transfer roller was as high as 0.99 and the collinearity was strong. However, the temperature Tb of the intermediate transfer member 3 can also be configured to be used as the evaluation value of the temperature before processing of the reference sheet. Alternatively, instead of the temperature Tt of the secondary transfer roller, the temperature Tb of the intermediate transfer member 3 can be used as the evaluation value of the temperature before processing of the reference sheet.

[0062] The flowchart regarding the fixing process according to the present embodiment is the same as FIG. 8. However, the evaluation value of the temperature before processing of the reference sheet in S13 is the temperature Tr of the pressure roller 6c, the temperature Tt of the secondary transfer roller 5, the temperature Tm of the conveyance path 46, and the operation mode (single-sided mode or duplex mode). Note that, for the temperatures Tr, Tm, and Tt used to evaluate the temperature before processing of the reference sheet, the temperatures at a predetermined timing while performing the fixing process on the image formed on the second side of the reference sheet can be used. For example, the predetermined timing can be the timing when the fixing process of the image formed on the second side of the reference sheet is completed. Alternatively, for the temperatures Tr, Tm, and Tt used to evaluate the temperature before processing of the reference sheet, statistical values during the fixing process of the image formed on the second side of the reference sheet, for example, average values, can be used.

[0063] In the present embodiment, even if the temperatures of the conveyance path 46 and the secondary transfer roller 5 change, the temperature before processing of the reference sheet can be accurately estimated. When using the temperature of the intermediate transfer member 3 instead of the temperature of the secondary transfer roller 5, the above secondary transfer roller 5 may be replaced with the intermediate transfer member 3. By being able to accurately estimate the temperature before processing, the amount of heat in the adhesion process can be appropriately controlled, and thus the power consumption in the adhesion process can be reduced.

[0064] (Comparison) FIG. 14 shows a comparative example between the case where the heating temperature in the adhesion process is set constant and the case where the heating temperature is controlled according to the content described in the present embodiment. In the experiment, the rising time of the fixing device 6 was set to 5 seconds, and one booklet made of 5 sheets P was created 30 sets every 5 seconds. Note that the single-sided mode and the double-sided mode were switched every set. Further, in each case, the heating time by the heating plate 502 was set to 2 seconds. Note that the heating temperature in the comparative example was set to 200°C.

[0065] FIG. 14 shows the results for the 1st, 2nd, 9th, 10th, 29th, and 30th sets. The pressure roller temperature, conveyance path temperature, and secondary transfer roller temperature in FIG. 14 respectively show the temperature Tr of the pressure roller 6c, the temperature Tm of the conveyance path 46, and the temperature Tt of the secondary transfer roller 5 estimated at the timing when the fixing process of the reference sheet is completed. The temperature before processing in FIG. 14 shows the temperature before processing of the reference sheet obtained based on Equation 13 or Equation 14. As shown in FIG. 14, the power consumption in the adhesion process can be reduced as compared with setting the heating temperature constant.

[0066] Note that, the higher the estimated temperature Tm of the conveyance path 46 becomes, the lower the heating temperature can be set, and the higher the estimated temperature Tt of the secondary transfer roller 5 (or the intermediate transfer member 3) becomes, the lower the heating temperature can be set. This is based on the fact that the higher the temperature Tm of the conveyance path 46 or the temperature Tt of the secondary transfer roller 5 (or the intermediate transfer member 3) becomes, the higher the temperature before processing of the reference sheet becomes. Further, the heating temperature in the double-sided mode can be set lower than the heating temperature in the single-sided mode. This is based on the fact that the temperature before processing of the reference sheet is higher in the double-sided mode than in the single-sided mode.

[0067] In addition, in this embodiment, the temperatures Tr, Tt, and Tm used as the evaluation values of the temperature of the reference sheet before processing were the temperatures during the fixing process of the reference sheet. This is based on the use of the model in FIG. 12. However, the temperature of the secondary transfer roller 5 (or the intermediate transfer member 3) used as the evaluation value of the temperature of the reference sheet before processing can be the temperature at a predetermined timing while the secondary transfer roller 5 is transferring an image to the second surface of the reference sheet. Similarly, the temperature Tm of the conveyance path 46 can also be the temperature at the timing when the reference sheet passes through a predetermined position of the conveyance path 46. In other words, the temperature of the member used as the evaluation value of the reference sheet can be the temperature of the member at the timing when the member is in contact with the reference sheet.

[0068] Note that the heat conduction model shown in FIG. 12 is an example, and the temperatures of the respective members can be obtained using other heat conduction models. Furthermore, a temperature sensor for measuring the temperature of each member can be provided, and the measured values of the temperatures of the respective members can also be used.

[0069] Also, as described in the second embodiment, a configuration can be adopted in which the temperature Tf of the heating film 6b is also used as the evaluation value of the temperature of the reference sheet before processing. That is, the temperature of the heating film 6b can be further used to evaluate the temperature of the reference sheet before processing. Furthermore, also in this embodiment, the temperature of the sheet bundle to be processed can be set to a value based on the temperature of any one or more sheets P included in the sheet bundle to be processed before processing.

[0070] <Fourth Embodiment> Subsequently, the fourth embodiment will be described focusing on the differences from the first embodiment. In the first embodiment, the temperature Tr of the pressure roller 6c was used as the evaluation value of the temperature before processing. In this embodiment, in addition to the temperature Tr of the pressure roller 6c, the ambient temperature Te measured by the temperature sensor 60 is also used.

[0071] When the ambient temperature (room temperature) changes, the temperature of the sheet P stored in the cassette 8 changes, and accordingly, the pre-treatment temperature also changes. FIG. 15 shows the results of an experiment in which the pre-treatment temperature was measured at different ambient temperatures Te. In the experiment, a total of three experiments were conducted to create three sets of booklets made of five sheets P every 5 seconds. The ambient temperature Te for each experiment was set to 15°C, 23°C, and 30°C, respectively. Also, at the start of each experiment, the temperature of the pressure roller 6c was set to the ambient temperature. Other conditions were the same for each experiment.

[0072] FIG. 15(A) shows the relationship between the temperature Tr of the pressure roller estimated at the timing when the fixing process of the reference sheet is completed and the pre-treatment temperature, and FIG. 15(B) shows the relationship between the ambient temperature Te and the pre-treatment temperature. From the results of FIGS. 15(A) and 15(B), the pre-treatment temperature Ta is obtained based on the following Equation 15. Ta = 0.0770Tr + 0.774Te + 28.362 (Equation 15)

[0073] The flowchart regarding the adhesion process according to the present embodiment is the same as FIG. 8. However, the evaluation value of the pre-treatment temperature of the reference sheet in S13 is the temperature Tr of the pressure roller 6c and the ambient temperature Te when the fixing process of the reference sheet is completed. Note that, as the ambient temperature Te used as the evaluation value of the pre-treatment temperature of the reference sheet, since the variation of the ambient temperature Te is gentle, a value at an arbitrary timing from the feeding of the reference sheet to the execution of the adhesion process can be used.

[0074] In the present embodiment, even if the ambient temperature Te varies, the pre-treatment temperature can be accurately estimated, and thus, the amount of heat in the adhesion process can be appropriately controlled. Therefore, the power consumption in the adhesion process can be reduced.

[0075] (Comparison) FIG. 16 shows a comparative example between the case where the heating temperature in the bonding process is set constant and the case where the heating temperature is controlled based on the content described in this embodiment. In the experiment, a total of three times, one booklet consisting of five sheets P was created three sets every 5 seconds. For each ambient temperature Te, it was set to 15°C, 23°C, and 30°C, respectively. Also, at the start of each time, the temperature of the pressure roller 6c was set to the ambient temperature. Other conditions were the same each time. The heating temperature in the comparative example was set to 204°C.

[0076] The pressure roller temperature in FIG. 16 shows the temperature Tr of the pressure roller 6c estimated at the timing when the fixing process of the reference sheet is completed. Also, the temperature before processing in FIG. 16 shows the value obtained according to Equation 15 from the temperature Tr of the pressure roller 6c and the ambient temperature Te. As shown in FIG. 16, the power consumption in the bonding process can be reduced compared to setting the heating temperature constant.

[0077] Note that without using the temperature Tr of the pressure roller 6c, it is also possible to adopt a configuration in which the heating temperature is set lower as the ambient temperature Te increases. This is based on the fact that as the ambient temperature Te increases, the temperature before processing of the reference sheet increases. Further, as described in the third embodiment, as an evaluation value of the temperature before processing of the reference sheet, the temperature of the heating film 6b, the temperature of the secondary transfer roller 5, the temperature Tm of the conveyance path 46, the temperature of the intermediate transfer body 3, and the operation mode (single-sided / double-sided) can also be further used.

[0078] <Fifth Embodiment> Subsequently, the fifth embodiment will be described centering on the differences from the first embodiment. In the first embodiment, the temperature Tr of the pressure roller 6c was used as the evaluation value of the temperature before processing. In this embodiment, in addition to the temperature Tr of the pressure roller 6c, the process speed is used.

[0079] The process speed is a value indicating the speed of image formation. The higher the process speed, the higher the conveyance speed of the sheet P and the rotation speed of the intermediate transfer body 3. Here, when the sheet P passes through the conveyance path 46, it is cooled by having heat taken away from it by the conveyance path 46. The slower the process speed, the longer the time it takes to pass through the conveyance path 46, and thus the lower the pre-treatment temperature. Fig. 17 shows the results of an experiment in which the pre-treatment temperature was measured at different process speeds Vp. In the experiment, a total of three experiments were conducted in which booklets made up of five sheets P were created three sets every five seconds. Note that the process speed Vp for each experiment was set to 321 mm / sec, 226 mm / sec, and 113 mm / sec, respectively. Also, at the start of each experiment, the temperature of the pressure roller 6c was set to the ambient temperature. Other conditions were the same for each experiment.

[0080] Fig. 17(A) shows the relationship between the temperature Tr of the pressure roller estimated at the timing when the fixing process of the reference sheet is completed and the pre-treatment temperature, and Fig. 17(B) shows the relationship between the process speed Vp and the pre-treatment temperature. From the results of Fig. 17(A) and Fig. 17(B), in the case of a process speed of 321 mm / sec, the pre-treatment temperature Ta is obtained based on the following Equation 16. Ta = 0.0789Tr + 45.9 (Equation 16) Also, in the case of a process speed of 226 mm / sec, the pre-treatment temperature Ta is obtained based on the following Equation 17. Ta = 0.0700Tr + 41.7 (Equation 17) Furthermore, in the case of a process speed of 113 mm / sec, the pre-treatment temperature Ta is obtained based on the following Equation 18 Ta = 0.0415Tr + 33.8 (Equation 18)

[0081] The flowchart regarding the fixing process according to this embodiment is the same as Fig. 8. However, the evaluation value of the pre-treatment temperature of the reference sheet in S13 is the temperature Tr of the pressure roller 6c and the process speed Vp.

[0082] In this embodiment, even if the process speed Vp is changed, the temperature before processing can be accurately estimated, and thus the amount of heat in the adhesion process can be appropriately controlled. Therefore, the power consumption in the adhesion process can be reduced.

[0083] (Comparison) FIG. 18 shows a comparative example between the case where the heating temperature in the adhesion process is set constant and the case where the heating temperature is controlled based on the content described in this embodiment. In the experiment, a total of three times were performed to create three sets of one booklet consisting of five sheets P every 5 seconds. For each process speed Vp, they were set to 321 mm / second, 226 mm / second, and 113 mm / second, respectively. Also, at the start of each time, the temperature of the pressure roller 6c was set to the ambient temperature. Other conditions were the same each time. The heating temperature in the comparative example was set to 208°C.

[0084] The temperature of the pressure roller in FIG. 18 shows the estimated temperature Tr of the pressure roller 6c estimated at the timing when the fixing process of the reference sheet is completed. Also, the temperature before processing in FIG. 18 shows the temperature before processing obtained according to Formulas 16 to 18. As shown in FIG. 18, the power consumption of the adhesion process can be reduced compared to setting the heating temperature constant.

[0085] Note that without using the temperature of the pressure roller 6c, it is also possible to adopt a configuration in which the heating temperature is set lower as the process speed increases. This is based on the fact that the temperature before processing of the reference sheet becomes higher as the process speed increases. Furthermore, as described in the fourth embodiment, as evaluation values of the temperature before processing of the reference sheet, the temperature of the heating film 6b, the temperature of the secondary transfer roller 5, the temperature Tm of the conveyance path 46, the temperature of the intermediate transfer body 3, the operation mode (single-sided / double-sided), and the ambient temperature can also be further used.

[0086] As described in the above embodiments, during the adhesion process, the temperatures of a plurality of sheets P to be subjected to the adhesion process are evaluated, and based on the evaluated temperatures, the amount of heat applied to the plurality of sheets P in the adhesion process is controlled. With this configuration, it is possible to prevent applying unnecessary heat to the sheet P, and thus, it is possible to suppress the power consumption in the adhesion process. Note that the amount of heat applied to the plurality of sheets P is made smaller as the evaluated temperature becomes higher.

[0087] As the temperatures of the plurality of sheets P, the temperature of a predetermined sheet among the plurality of sheets P during the adhesion process can be used. Here, the predetermined sheet can be the sheet located at the position farthest from the heating plate 502 among the plurality of sheets P. The plurality of sheets P correspond to the sheet bundle to be processed in the above embodiment.

[0088] Note that, as described in the first embodiment, the temperature of the predetermined sheet can be configured to be evaluated based on the measurement result of the temperature of the predetermined sheet after the fixing process is performed by the fixing device 6. Also, as described in the first embodiment, the temperature of the predetermined sheet can be configured to be evaluated based on the rise time. Furthermore, as described in the above embodiment, the temperature of the predetermined sheet can be evaluated using one or more of the temperatures of the pressure roller 6c, the heating film 6b, the secondary transfer roller 5, the intermediate conveyance path 46, and the intermediate transfer body 3, the environmental temperature, the process speed, the operation mode (single-sided / double-sided), and the rise time.

[0089] Note that the pressure roller 6c, the heating film 6b, the secondary transfer roller 5, the intermediate conveyance path 46, and the intermediate transfer body 3 are examples of members in which heat conduction occurs between the sheet P. Therefore, the temperature of the predetermined sheet can be evaluated based on the temperature of at least one or more members in which heat conduction occurs between the sheet P, and the present invention is not limited to using the members listed above.

[0090] Note that the temperature of one or more members used to evaluate the temperature of a predetermined sheet can be the temperature of the member when the member is in contact with the predetermined sheet. Also, in the case of a member with a gentle temperature change, the temperature at a predetermined timing when the member is not in contact with the predetermined sheet can also be used. As an example, the temperature of one or more members at a predetermined timing while the fixing process of the predetermined sheet by the fixing device 6 is being performed can be used to evaluate the temperature of the predetermined sheet. Alternatively, the temperature at a predetermined timing from when the fixing process is performed until the bonding process is performed can also be used.

[0091] Note that it is not necessary to obtain the temperature during the bonding process of the predetermined sheet among the plurality of sheets P to be subjected to the bonding process. That is, it is also possible to store in the control unit 100 determination information indicating the relationship between one or more parameter values among one or more members that cause heat conduction with the sheet P, the ambient temperature, the process speed, the operation mode (single-sided / double-sided), and the start-up time, and the amount of heat applied to the plurality of sheets P in the bonding process, and to control the amount of heat based on the parameter values and the determination information.

[0092] [Other Embodiments] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0093] The disclosure of this embodiment includes the following configurations. (Configuration 1) An image forming apparatus, image forming means for forming an image including an adhesive image with a powder adhesive on a conveyed sheet; An adhesion means for sequentially conveying the sheet on which the image has been formed by the image forming means, the adhesion means heating a plurality of sheets conveyed and stacked thereon, and adhering the plurality of sheets by the adhesive images formed on the plurality of sheets. Control means for evaluating the temperature of the plurality of sheets conveyed to the adhesion means and controlling the amount of heat applied to the plurality of sheets by heating the plurality of sheets by the adhesion means based on the evaluated temperature. An image forming apparatus comprising the above. (Configuration 2) The control means reduces the amount of heat as the evaluated temperature increases, the image forming apparatus according to Configuration 1. (Configuration 3) The image forming means Transfer means for transferring the image to the sheet, A fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet. The image forming apparatus includes first measuring means for measuring the temperature of the sheet after the fixing process is performed by the fixing means. The control means evaluates the temperature of the plurality of sheets based on the measurement result by the first measuring means, the image forming apparatus according to Configuration 1 or 2. (Configuration 4) The image forming means Transfer means for transferring the image to the sheet, A fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet. The control means evaluates the temperature of the plurality of sheets based on the temperature of the pressing member, the image forming apparatus according to Configuration 1 or 2. (Configuration 5) The image forming means Transfer means for transferring the image to the sheet, A fixing unit that has a heating member for heating the sheet and a pressing member for pressing the sheet, and performs a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet. The control unit evaluates the temperature of the plurality of sheets based on the period during which the heating member was heated before the fixing unit started the fixing process on the plurality of sheets. The image forming apparatus according to Configuration 1 or 2. (Configuration 6) The image forming unit A transfer unit that transfers the image to the sheet, A fixing unit that has a heating member for heating the sheet and a pressing member for pressing the sheet, and performs a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet. The control unit evaluates the temperature of the plurality of sheets based on the temperature of the heating member. The image forming apparatus according to Configuration 1 or 2. (Configuration 7) The image forming unit A transfer unit that transfers the image formed on the intermediate transfer member to the sheet, A fixing unit that has a heating member for heating the sheet and a pressing member for pressing the sheet, and performs a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet. The image forming apparatus has a conveyance path connecting the fixing unit and the adhesion unit, and operates in either a single-sided mode of forming an image on only one side of the sheet or a double-sided mode of forming images on both sides of the sheet. The control unit evaluates the temperature of the plurality of sheets based on at least one of the temperature of the intermediate transfer member, the temperature of the transfer unit, the temperature of the conveyance path, and the operation mode. The image forming apparatus according to Claim Configuration 1 or 2. (Configuration 8) Further includes a second measuring unit for measuring the ambient temperature, The control unit evaluates the temperature of the plurality of sheets based on the ambient temperature. The image forming apparatus according to Configuration 1 or 2. (Configuration 9) The image forming apparatus according to Configuration 1 or 2, wherein the control means evaluates the temperature of the plurality of sheets based on the conveyance speed of the sheets. (Configuration 10) The image forming apparatus according to Configuration 6 or 7, wherein the control means further evaluates the temperature of the plurality of sheets based on the temperature of the pressing member. (Configuration 11) The image forming means transfer means for transferring the image onto the sheet; a heating member for heating the sheet and a pressing member for pressing the sheet, and fixing means for fixing the image transferred onto the sheet to the sheet by heating and pressing the sheet. The image forming apparatus according to Configuration 8 or 9, wherein the control means further evaluates the temperature of the plurality of sheets based on the temperature of the pressing member. (Configuration 12) The image forming apparatus according to any one of Configurations 1 to 12, wherein the control means evaluates the temperature of a reference sheet among the plurality of sheets. (Configuration 13) The adhering means has a heating part, The control means performs an adhering process of heating and adhering the plurality of sheets stacked on the adhering means by the heating part when a predetermined number of sheets among the plurality of sheets constituting one booklet are conveyed to and stacked on the adhering means, and when the last sheet among the plurality of sheets constituting one booklet is conveyed to and stacked on the adhering means. The reference sheet is a sheet located at the position farthest from the heating part among one or more sheets stacked on the adhering means and not heated by the heating part. The image forming apparatus according to Configuration 12. (Configuration 14) An image forming apparatus, image forming means for forming an image including an adhesive image with a powder adhesive on a conveyed sheet; An adhering means for sequentially conveying the sheet on which the image has been formed by the image forming means, the adhering means heating a plurality of sheets conveyed and stacked thereon, and adhering the plurality of sheets by the adhesive images formed on the plurality of sheets. A control means for controlling the amount of heat applied to the plurality of sheets by the adhering means heating the plurality of sheets. Comprising: The control means controls the amount of heat applied to the plurality of sheets based on the temperature of at least one member where heat conduction occurs between the sheet and the environment temperature, an image forming apparatus. (Configuration 15) The image forming means includes: A transfer roller for transferring the image formed on the intermediate transfer body to the sheet, A fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet on the sheet by heating and pressing the sheet. The image forming apparatus has a conveyance path connecting the fixing means and the adhering means. The at least one member includes one or more of the heating member, the pressing member, the intermediate transfer body, the transfer roller, and the conveyance path, the image forming apparatus according to Configuration 14. (Configuration 16) The control means controls the amount of heat applied to the plurality of sheets based on the temperature of the at least one member when a reference sheet among the plurality of sheets is in contact with the at least one member, the image forming apparatus according to Configuration 14 or 15. (Configuration 17) The control means controls the amount of heat applied to the plurality of sheets based on the temperature of the at least one member when the fixing process for a reference sheet among the plurality of sheets is completed, the image forming apparatus according to Configuration 15 or 16. (Configuration 18) The adhering means has a heating part. The control means performs an adhesion process of heating and adhering the plurality of sheets loaded on the adhesion means by the heating unit when a predetermined number of sheets among the plurality of sheets constituting one booklet are conveyed and loaded on the adhesion means, and when the last sheet among the plurality of sheets constituting the one booklet is conveyed and loaded on the adhesion means. The reference sheet is the sheet located at the position farthest from the heating unit among one or more sheets loaded on the adhesion means and not heated by the heating unit. The image forming apparatus according to Configuration 17. (Configuration 19) The control means reduces the amount of heat applied to the plurality of sheets as the temperature of the at least one member increases. The image forming apparatus according to any one of Configurations 14 to 18. (Configuration 20) The control means reduces the amount of heat applied to the plurality of sheets as the ambient temperature increases. The image forming apparatus according to any one of Configurations 14 to 18. (Configuration 21) An image forming apparatus, image forming means for forming an image including an adhesive image by a powder adhesive on a conveyed sheet; adhesion means for sequentially conveying the sheet on which the image is formed by the image forming means, and heating the plurality of sheets loaded on the adhesion means to adhere the plurality of sheets by the adhesive image formed on the plurality of sheets; control means for controlling the amount of heat applied to the plurality of sheets by the adhesion means heating the plurality of sheets; comprising, The control means controls the amount of heat applied to the plurality of sheets based on the conveyance speed of the sheet or the operation mode, either a single-sided mode in which an image is formed on only one side of the sheet or a double-sided mode in which an image is formed on both sides of the sheet. An image forming apparatus. (Configuration 22) The control means reduces the amount of heat applied to the plurality of sheets as the conveyance speed increases. The image forming apparatus according to Configuration 21. (Configuration 23) The image forming apparatus according to Configuration 21, wherein when operating in the double-sided mode, the control means reduces the amount of heat applied to the plurality of sheets compared to when operating in the single-sided mode. (Configuration 24) An image forming apparatus, comprising: image forming means for forming an image including an adhesive image by a powder adhesive on a conveyed sheet; adhesive means for sequentially conveying the sheet on which the image has been formed by the image forming means, and heating the plurality of sheets conveyed and stacked on the adhesive means to bond the plurality of sheets by the adhesive images formed on the plurality of sheets; control means for controlling the amount of heat applied to the plurality of sheets by heating the plurality of sheets by the adhesive means; and comprising: wherein the image forming means includes: transfer means for transferring the image to the sheet; fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet; The image forming apparatus, wherein the control means controls the amount of heat applied to the plurality of sheets based on the period during which the heating member is heated before the fixing means starts the fixing process for the plurality of sheets. (Configuration 25) The image forming apparatus according to Configuration 24, wherein the control means reduces the amount of heat applied to the plurality of sheets as the period during which the heating member is heated before the fixing means starts the fixing process for the plurality of sheets becomes longer. (Configuration 26) The image forming apparatus according to any one of Configurations 1 to 25, wherein the control means controls the amount of heat applied to the plurality of sheets by controlling one or both of the heating time for heating the plurality of sheets by the adhesive means and the heating temperature during the heating time. (Configuration 27) The image forming apparatus according to any one of claims 1 to 26, wherein the powder adhesive is toner used for forming an image different from the adhesive image.

[0094] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the claims are appended to disclose the scope of the invention.

Description of reference numerals

[0095] 7Y, 7M, 7C, 7K: forming unit, 2: scanner unit, 5: secondary transfer roller, 6: fixing unit, 51: thermocompression bonding unit, 100: control unit

Claims

1. An image forming apparatus, comprising: image forming means for forming an image including an adhesive image by a powder adhesive on a conveyed sheet; adhesive means for sequentially conveying the sheet on which the image has been formed by the image forming means, and heating a plurality of sheets conveyed and stacked on the adhesive means to bond the plurality of sheets by the adhesive images formed on the plurality of sheets; control means for evaluating the temperature of the plurality of sheets conveyed to the adhesive means and controlling the amount of heat applied to the plurality of sheets by heating the plurality of sheets by the adhesive means based on the evaluated temperature; An image forming apparatus comprising the above.

2. The image forming apparatus according to claim 1, wherein the control means reduces the amount of heat as the evaluated temperature increases.

3. The image forming means includes: transfer means for transferring the image to the sheet; fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet; The image forming apparatus includes first measuring means for measuring the temperature of the sheet after the fixing process is performed by the fixing means; The control means evaluates the temperature of the plurality of sheets based on the measurement result by the first measuring means.

4. The image forming means includes: transfer means for transferring the image to the sheet; fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet; The control means evaluates the temperature of the plurality of sheets based on the temperature of the pressing member.

5. The image forming means includes: transfer means for transferring the image to the sheet; fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred to the sheet to the sheet by heating and pressing the sheet; The control means evaluates the temperature of the plurality of sheets based on the period during which the heating member has been heated before the fixing means starts the fixing process for the plurality of sheets.

6. The image forming means includes transfer means for transferring the image onto the sheet, a fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and fixing the image transferred onto the sheet to the sheet by heating and pressing the sheet. The control means evaluates the temperature of the plurality of sheets based on the temperature of the heating member. The image forming apparatus according to claim 1. **Claim 7** The image forming means includes transfer means for transferring the image formed on the intermediate transfer body onto the sheet, a fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and fixing the image transferred onto the sheet to the sheet by heating and pressing the sheet. The image forming apparatus has a conveyance path connecting the fixing means and the adhesion means, and operates in any one of a single-sided mode of forming an image on only one side of the sheet and a double-sided mode of forming images on both sides of the sheet. The control means evaluates the temperature of the plurality of sheets based on at least one of the temperature of the intermediate transfer body, the temperature of the transfer means, the temperature of the conveyance path, and the operation mode. The image forming apparatus according to claim 1. **Claim 8** The image forming apparatus further includes second measuring means for measuring the ambient temperature. The control means evaluates the temperature of the plurality of sheets based on the ambient temperature. The image forming apparatus according to claim 1. **Claim 9** The control means evaluates the temperature of the plurality of sheets based on the conveyance speed of the sheet. The image forming apparatus according to claim 1. **Claim 10** The control means further evaluates the temperature of the plurality of sheets based on the temperature of the pressing member. The image forming apparatus according to claim 6 or 7. **Claim 11** The image forming means includes transfer means for transferring the image onto the sheet, a fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and fixing the image transferred onto the sheet to the sheet by heating and pressing the sheet. The control means further evaluates the temperature of the plurality of sheets based on the temperature of the pressing member. The image forming apparatus according to claim 8 or 9. **Claim 12** The control means evaluates the temperature of a reference sheet among the plurality of sheets. The image forming apparatus according to any one of claims 1 to 9. **Claim 13** The adhesion means has a heating section. The control means performs an adhesion process of heating and adhering the plurality of sheets loaded on the adhesion means by the heating unit when a predetermined number of sheets among the plurality of sheets constituting one booklet are conveyed and loaded on the adhesion means, and when the last sheet among the plurality of sheets constituting one booklet is conveyed and loaded on the adhesion means. The reference sheet is the sheet located at the position farthest from the heating unit among one or more sheets that are loaded on the adhesion means and not heated by the heating unit. The image forming apparatus according to claim 12.

14. An image forming apparatus, image forming means for forming an image including an adhesive image with a powder adhesive on a conveyed sheet; an adhesion means for sequentially conveying the sheet on which the image has been formed by the image forming means, and heating the plurality of sheets conveyed and loaded on the adhesion means to adhere the plurality of sheets by the adhesive images formed on the plurality of sheets; control means for controlling the amount of heat applied to the plurality of sheets based on the temperature of at least one member that generates heat conduction with the sheet or the ambient temperature; comprising: The control means controls the amount of heat applied to the plurality of sheets based on the temperature of at least one member that generates heat conduction with the sheet or the ambient temperature. An image forming apparatus.

15. The image forming means includes: a transfer roller for transferring the image formed on the intermediate transfer body to the sheet; a fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process of fixing the image transferred to the sheet to the sheet by heating and pressing the sheet; The image forming apparatus has a conveyance path connecting the fixing means and the adhesion means. The at least one member includes one or more of the heating member, the pressing member, the intermediate transfer body, the transfer roller, and the conveyance path. The image forming apparatus according to claim 14.

16. The control means controls the amount of heat applied to the plurality of sheets based on the temperature of the at least one member when a reference sheet among the plurality of sheets is in contact with the at least one member. The image forming apparatus according to claim 14.

17. The image forming apparatus according to claim 15, wherein the control means controls the amount of heat applied to the plurality of sheets based on the temperature of the at least one member when fixing processing on a reference sheet among the plurality of sheets is completed.

18. The adhering means has a heating unit, The control means performs an adhering process of heating and adhering the plurality of sheets stacked on the adhering means by the heating unit when a predetermined number of sheets among the plurality of sheets constituting one booklet are conveyed to and stacked on the adhering means, and when the last sheet among the plurality of sheets constituting one booklet is conveyed to and stacked on the adhering means. The reference sheet is a sheet located at the position farthest from the heating unit among one or more sheets stacked on the adhering means and not heated by the heating unit. The image forming apparatus according to claim 17.

19. The image forming apparatus according to claim 14, wherein the control means reduces the amount of heat applied to the plurality of sheets as the temperature of the at least one member increases.

20. The image forming apparatus according to claim 14, wherein the control means reduces the amount of heat applied to the plurality of sheets as the ambient temperature increases.

21. An image forming apparatus, image forming means for forming an image including an adhesive image with a powder adhesive on a conveyed sheet; adhering means for sequentially conveying the sheet on which the image has been formed by the image forming means, and adhering the plurality of sheets by the adhesive image formed on the plurality of sheets by heating the plurality of sheets stacked on the adhering means; control means for controlling the amount of heat applied to the plurality of sheets by the adhering means heating the plurality of sheets; comprising: The control means controls the amount of heat applied to the plurality of sheets based on the conveyance speed of the sheet or which operation mode of a single-sided mode of forming an image on only one side of the sheet and a double-sided mode of forming an image on both sides of the sheet the apparatus is operating in. An image forming apparatus.

22. The image forming apparatus according to claim 21, wherein the control means reduces the amount of heat applied to the plurality of sheets as the conveyance speed increases.

23. The image forming apparatus according to claim 21, wherein the control means reduces the amount of heat applied to the plurality of sheets when operating in the duplex mode as compared to when operating in the simplex mode.

24. An image forming apparatus, image forming means for forming an image including an adhesive image with a powder adhesive on a conveyed sheet; adhesive means for sequentially conveying the sheet on which the image has been formed by the image forming means, and heating the plurality of sheets conveyed and stacked on the adhesive means to bond the plurality of sheets by the adhesive image formed on the plurality of sheets; control means for controlling the amount of heat applied to the plurality of sheets by the adhesive means heating the plurality of sheets; comprising: The image forming means includes: transfer means for transferring the image onto the sheet; fixing means having a heating member for heating the sheet and a pressing member for pressing the sheet, and performing a fixing process for fixing the image transferred onto the sheet onto the sheet by heating and pressing the sheet; The control means controls the amount of heat applied to the plurality of sheets based on the period during which the heating member is heated before the fixing means starts the fixing process on the plurality of sheets.

25. The image forming apparatus according to claim 24, wherein the control means reduces the amount of heat applied to the plurality of sheets as the period during which the heating member is heated before the fixing means starts the fixing process on the plurality of sheets becomes longer.

26. The image forming apparatus according to any one of claims 1 to 9 and 14 to 25, wherein the control means controls the amount of heat applied to the plurality of sheets by controlling one or both of the heating time for the adhesive means to heat the plurality of sheets and the heating temperature during the heating time.

27. The image forming apparatus according to any one of claims 1 to 9 and 14 to 25, wherein the powder adhesive is toner used also for forming an image different from the adhesive image.

Images