Image forming apparatus and image forming system

Abstract

To prevent current consumption from exceeding a standard value in an image forming apparatus that heats a plurality of sheets with a heater to bond the sheets to each other, thereby creating a booklet.SOLUTION: Fixing means has a first heater that fixes an image to a sheet. Booklet creation means heats a plurality of sheets with a second heater to bond the sheets to each other, thereby creating a booklet. The first heater and the second heater are supplied with power through an inlet. Control means adjusts the power supplied to the second heater so as to prevent inlet current from exceeding a rated value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and an image forming system. [Background technology]

[0002] A printer system may have an image forming device that fixes a toner image on a sheet using a fixing heater, and an optional device that staples a stack of sheets using a stapler. The stapler requires a large current during operation, but the current consumption of the printer system must not exceed a standard value stipulated by law. Therefore, Patent Document 1 proposes that the image forming device suppresses the power supplied to the fixing heater when it receives a notice of the use of the stapler from the optional device and determines that the current consumption will exceed the standard value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5361505 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, since the time for which the drive current is passed through the stapler is extremely short, the time for which the power supplied to the fixing heater is suppressed may also be extremely short. However, in a booklet production device that employs a heater for booklet production that binds a sheet stack with adhesive toner without using staples, the time for which the power supplied to the fixing heater is suppressed is long. This is because the time required to start the heater for booklet production is longer than the operation time of the stapler. When the power supply to the fixing heater is suppressed, the time required for the temperature of the fixing heater to reach the target temperature increases. As a result, the time required to form a toner image on a sheet also increases. Therefore, an object of the present invention is to make it difficult for the current consumption in an image forming device that heats and adheres multiple sheets with a heater to produce a booklet to exceed a standard value. [Means for solving the problem]

[0005] The present invention relates to, for example, an image forming means for forming an image on a sheet using toner; a fixing means having a first heater for fixing the image onto the sheet; a booklet producing means for producing a booklet by heating and bonding the plurality of sheets that have passed through the fixing means by a second heater; an inlet for supplying power to the first heater and the second heater; A first detection means for detecting an inlet current flowing through the inlet; a control means for controlling the power supplied from the inlet to the first heater and the second heater, The control unit adjusts the power supplied to the second heater based on the inlet current detected by the first detection unit so that the inlet current does not exceed a rated value. Effect of the Invention

[0006] According to the present invention, the current consumption in an image forming apparatus that heats and bonds a plurality of sheets with a heater to produce a booklet is less likely to exceed a standard value. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an image forming system. [Diagram 2] FIG. 1 is a diagram illustrating an area where adhesive toner is applied; [Diagram 3] FIG. 3 is a plan view illustrating the thermocompression bonding unit. [Figure 4] A diagram explaining the thermocompression process [Diagram 5] Diagram explaining the control system [Figure 6] Diagram explaining the change in inlet current and heater current [Figure 7] A diagram explaining the printer control unit [Figure 8] Flowchart for explaining heater power control [Figure 9] Diagram explaining the change in inlet current and heater current [Figure 10] A diagram explaining the printer control unit [Figure 11] Flowchart for explaining heater power control [Figure 12] Diagram explaining the control system [Figure 13] A diagram explaining the printer control unit [Figure 14] Flowchart for explaining heater power control DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0009] <Example 1> (1) Image forming system 1, the image forming system 1 includes an image forming apparatus 100 and a post-processing apparatus 130. The post-processing apparatus 130 is a sheet processing apparatus connected to the image forming apparatus 100. The image forming apparatus 100 forms an image on a sheet S, which is a recording material. The intermediate conveying unit 120 conveys the sheet S on which the image has been formed to the post-processing apparatus 130. The post-processing apparatus 130 performs post-processing on the sheet S as necessary and outputs it.

[0010] The image forming apparatus 100 includes a sheet cassette 8, an image forming unit 10, a fixing unit 6, and a housing 19 that houses these components. The image forming unit 10 forms a toner image on a sheet S fed from the sheet cassette 8. The fixing unit 6 performs a fixing process to fix the toner image on the sheet S.

[0011] The sheet cassette 8 is provided at the bottom of the image forming apparatus 100. The sheet cassette 8 is inserted into the housing 9 so as to be removable, and can store a large number of sheets S. A feed roller 81 feeds the sheet S from the sheet cassette 8, and delivers the sheet S to a conveying roller pair 82. The multi-tray 20 can also feed the sheets S one by one.

[0012] The image forming section 10 is a tandem-type electrophotographic unit including four process cartridges 7n, 7y, 7m, and 7c, an exposure device 2, and a transfer unit 3. ymc means yellow, magenta, and cyan, respectively. n means adhesive toner. The color of the adhesive toner may be transparent or black. When the color of the adhesive toner is transparent, black is realized by appropriately mixing yellow, magenta, and cyan (process black). The process cartridges 7n, 7y, 7m, and 7c allow multiple parts that are responsible for the image forming process to be replaced as a whole. In other words, the process cartridges 7n, 7y, 7m, and 7c are formed by integrating multiple parts.

[0013] The process cartridges 7n, 7y, 7m, and 7c have corresponding developing devices Kn, Ky, Km, and Kc, photoconductor drums Dn, Dy, Dm, and Dc, and charging rollers Cn, Cy, Cm, and Cc. The structure of the process cartridges 7n, 7y, 7m, and 7c is substantially the same, except for the type of toner.

[0014] The developing devices Ky, Km, Kc contain yellow, magenta, and cyan toners for forming a visible image on the sheet S. The developing device Kn contains adhesive toner Tn. The adhesive toner Tn is used to form a user image (original image) and to thermally press a plurality of sheets S together in the post-processing device 130. An image made of the adhesive toner Tn is formed on the photoconductor drum Dn by development using the adhesive toner Tn.

[0015] The image forming unit 10 may have a fifth process cartridge that uses a toner exclusively for adhesion or a black toner. The type and number of printing toners can be changed depending on the application of the image forming apparatus 100.

[0016] The charging rollers Cn, Cy, Cm, and Cc are chargers that uniformly charge the surfaces of the corresponding charging rollers Cn, Cy, Cm, and Cc. The exposure device 2 is disposed below the process cartridges 7n, 7y, 7m, and 7c and above the sheet cassette 8. The exposure device 2 irradiates the photosensitive drums Dn, Dy, Dm, and Dc with corresponding laser beams Jn, Jy, Jm, and Jc to form electrostatic latent images. The exposure device 2 may also be called an optical scanning device.

[0017] The developing devices Kn, Ky, Km, and Kc form toner images by attaching toner to the electrostatic latent images on the photoconductor drums Dn, Dy, Dm, and Dc. The developing devices Kn, Ky, Km, and Kc may also be called developers.

[0018] The transfer unit 3 includes a transfer belt 30 as an intermediate transfer body (secondary image carrier). The transfer belt 30 is an endless belt wound around an inner roller 31 and a tension roller 32. The outer peripheral surface (image forming surface) of the transfer belt 30 faces the photosensitive drums Dn, Dy, Dm, and Dc. Primary transfer rollers Fn, Fy, Fm, and Fc are disposed on the inner peripheral side of the transfer belt 30 so as to face the photosensitive drums Dn, Dy, Dm, and Dc.

[0019] The primary transfer rollers Fn, Fy, Fm, and Fc transfer the toner images from the corresponding photoconductor drums Dn, Dy, Dm, and Dc to the transfer belt 30. The primary transfer rollers Fn, Fy, Fm, and Fc may be called primary transfer devices. The toner images are transported to the secondary transfer section by the counterclockwise rotation of the transfer belt 30.

[0020] The secondary transfer roller 5 is disposed to face the inner roller 31, and forms a transfer nip 52 between the secondary transfer roller 5 and the transfer belt 30. The transfer nip 52 transfers the toner image from the transfer belt 30 to the sheet S. The transfer nip 52 may be referred to as a secondary transfer portion.

[0021] A fixing unit 6 is disposed above the secondary transfer roller 5 (downstream in the conveying direction of the sheet S). The fixing unit 6 applies heat and pressure to the sheet S passing through a fixing nip 61. This causes the toner image to be fixed onto the sheet S. The fixing unit 6 has a fixing heater 62 for heating the toner image and the sheet S. The fixing heater 62 is, for example, a halogen heater or a ceramic heater.

[0022] FIG. 2(A) shows a printing area 211 of adhesive toner Tn. The printing area 211 extends parallel to the long side of the sheet S. The printing area 211 is provided at the end close to the long side. As a result, the post-processing device 130 stacks multiple sheets S and heats and presses the printing areas 211 of the multiple sheets S, thereby adhering the multiple sheets S to form a booklet. The booklet in this case is a long-side bound booklet. Here, the width (length in the short side direction) of the adhesive toner image (printing area 211) is, for example, 4.0 mm.

[0023] 2B, a small print area 212 for adhesive toner Tn may be formed near the corner of the sheet S. This produces a booklet with corner fastenings. An image using adhesive toner Tn is not formed on the sheet S that will be the cover of the booklet.

[0024] Returning to the description of FIG. 1, as shown in FIG. 1, the switching guide 33 is a flap-shaped guide member provided downstream of the fixing unit 6 in the conveying direction of the sheet S. When a single-sided printing mode in which an image is formed on one side of the sheet S is selected, the switching guide 33 guides the sheet S to a discharge roller 34. When a double-sided printing mode in which an image is formed on both sides of the sheet S is selected, the switching guide 33 guides the sheet S with an image formed on the first side to a switchback roller pair 35. The switchback roller pair 35 conveys the sheet S in a first direction. When the rear end of the sheet S is in a state in which it can enter the double-sided conveying path 36, the switchback roller pair 35 starts to reverse. As a result, the sheet S is conveyed to the double-sided conveying path 36. The double-sided conveying path 36 conveys the sheet S again to the secondary transfer unit. As a result, an image is formed on the second side of the sheet S.

[0025] The discharge roller 34 conveys the sheet S to an intermediate conveying unit 120. The intermediate conveying unit 120 has a pair of conveying rollers 121 and 122. The pair of conveying rollers 121 and 122 convey the sheet S to a post-processing device 130.

[0026] (2) After-treatment device The post-processing device 130 is a floor-standing type sheet processing device and has a function of buffering a plurality of sheets, a function of aligning a plurality of sheets, and a function of gluing a sheet stack.

[0027] In the following, the end of the sheet S on the front side in the transport direction is referred to as the leading end. The end of the sheet S on the rear side in the transport direction is referred to as the trailing end. Of the two ends of the sheet S, the end that enters the post-processing device 130 first is referred to as the first end. Of the two ends of the sheet S, the end that enters the post-processing device 130 later is referred to as the second end. Note that the leading end may be changed from the first end to the second end and the trailing end may be changed from the second end to the first end due to the switchback transport performed by the post-processing device 130.

[0028] The sheet S conveyed from the intermediate conveying unit 120 is delivered to the entrance rollers 21 of the post-processing device 130. A sheet sensor 27, also called an entrance sensor, is disposed downstream of the entrance rollers 21. When the sheet sensor 27 detects the rear end of the sheet S, the conveying roller pair 22 accelerates the sheet S. When the rear end of the sheet S, whose discharge destination is set to the upper tray 25, arrives between the conveying roller pair 22 and the conveying roller pair 24, the conveying roller pair 22 decelerates. This causes the conveying speed of the sheet S to become a predetermined discharge speed. The conveying roller pair 22 discharges the sheet S to the upper tray 25.

[0029] When the trailing end of the sheet S, the discharge destination of which is set to the lower tray 37, passes through the check valve 23, the conveying roller pair 22 stops conveying the sheet S. After that, the conveying roller pair 22 starts to rotate in the reverse direction. As a result, the sheet S switches back and is conveyed to the conveying roller pair 26. When the sheet sensor 60 provided downstream of the conveying roller pair 26 detects the leading end of the sheet S, the two rollers constituting the conveying roller pair 24 separate. As a result, the conveying roller pair 24 becomes capable of receiving the following sheet S. Furthermore, the conveying roller pair 26 stops with the preceding sheet S sandwiched between them. The conveying roller pair 26 starts to rotate in the reverse direction in response to the arrival of the following sheet S. As a result, the following sheet S is stacked on top of the preceding sheet S. By repeating the switchback of the sheet S by the conveying roller pair 26, a plurality of sheets S are stacked to form a sheet bundle. Such a sheet bundle forming operation may be called a buffer operation. A unit that realizes the buffer operation is called a buffer unit 80.

[0030] When the sheet stack is completed in the buffer unit 80, the conveying roller pair 26 conveys the sheet stack toward the intermediate stacking unit 42. The sheet stack passes through the conveying roller pair 28 and the sheet sensor 50. The sheet stack is further conveyed to the intermediate stacking unit 42 by the kick-out roller 29. A movable vertical alignment plate 39 is disposed in a standby position at the most downstream portion of the intermediate stacking unit 42. The sheet stack is aligned by hitting the vertical alignment plate 39.

[0031] A plurality of sheet bundles are stacked in sequence on the intermediate stacking section 42. As a result, a predetermined number of sheets S that form a booklet are stacked on the intermediate stacking section 42. When the alignment of the predetermined number of sheets S is completed, the thermocompression bonding unit 51 performs a binding operation (thermocompression bonding process) to form a booklet. The vertical alignment plate 39 moves from the standby position to the discharge position, pushing the booklet toward the discharge rollers 38. When the leading edge of the booklet is clamped by the discharge rollers 38, the vertical alignment plate 39 stops and returns to the standby position again. The discharge rollers 38 discharge the booklet received from the vertical alignment plate 39 from the discharge port 46 to the lower tray 37.

[0032] In the above description, the post-processing device 130 forms a sheet bundle consisting of a plurality of sheets S by using the buffer unit 80, and conveys the sheet bundle to the intermediate stacking unit 42. However, a single sheet S may be conveyed to the intermediate stacking unit 42.

[0033] (3) Booklet production operation 3A to 3D show the booklet production operation executed in the intermediate stacking unit 42. In the initial state, the intermediate stacking unit 42 is empty. As an example, a sheet bundle W consisting of five sheets S is conveyed from the buffer unit 80 to the intermediate stacking unit 42.

[0034] The Y direction is a direction parallel to the stacking surface (stack plate) of the sheets S in the intermediate stacking section 42 and parallel to the transport direction of the sheets S transported from the kick-out roller 29 to the intermediate stacking section 42. The Y direction may be called the vertical direction. The X direction is a direction parallel to the stacking surface of the sheets S in the intermediate stacking section 42 and perpendicular to the Y direction. The X direction may be called the horizontal direction. The Z direction is a direction perpendicular to the X and Y directions (the normal direction of the stacking surface, the thickness direction of the stacked sheets S). The Z direction may be called the height direction. The opposite directions of the X, Y, and Z directions may be called the -X, -Y, and -Z directions, respectively.

[0035] The vertical alignment plate 39 and the vertical alignment roller 40 function as a first alignment unit that aligns a plurality of sheets S in a first direction (Y direction). The vertical alignment plate 39 is disposed at the most downstream portion of the intermediate stacking portion 42 in the Y direction. The vertical alignment plate 39 is a reference member (first reference member) that serves as a reference for the sheet position in the Y direction. The vertical alignment roller 40 is a conveying member that conveys the sheet S in the Y direction so that the sheet S is abutted against the vertical alignment plate 39 for alignment. The vertical alignment plate 39 includes a plurality of contact portions 39a to 39c that are spaced apart in the X direction. The plurality of contact portions 39a to 39c come into contact with the end of the sheet S. The vertical alignment plate 39 and the vertical alignment roller 40 are integrally configured as a movable unit 59 that is movable in the Y direction. The movable unit 59 is movable in the Y direction by a driving source such as a motor. That is, the positions of the vertical alignment plate 39 and the vertical alignment roller 40 in the Y direction are adjustable. The lateral alignment joggers 41a to 41c function as a second alignment unit that aligns the sheet in a second direction (X direction) perpendicular to the first direction.

[0036] The lateral alignment joggers 41a to 41c are moved in the X direction by a driving source such as a motor, and press the side edges of the sheets S stacked on the intermediate stacker 42. The lateral alignment plates 72a and 72b are reference members that serve as references for the position of the sheets S in the X direction. The lateral alignment plates 72a and 72b are disposed to face the lateral alignment joggers 41a and 41b in the X direction.

[0037] (3-1) Preparation stage As shown in FIG. 3A, the sheets S1 to S5 are conveyed toward the kick-out roller 29. The sheets S1 to S5 may be conveyed to the intermediate stacking unit 42 in a state in which the lower sheet Si protrudes in the Y direction from the upper sheet Si+1. Here, i is the index of the sheets S. Before the sheets S are stacked on the intermediate stacking unit 42, the vertical alignment plate 39 moves to a predetermined standby position in advance according to the size of the sheet S to be aligned. The standby position is set so that the end position of the sheet S in the -Y direction is constant, regardless of the size of the sheet S. In other words, the standby position is a position where the distance in the Y direction from the nip position of the kick-out roller 29 to the vertical alignment plate 39 is slightly longer than the length of the sheet in the Y direction. The horizontal alignment joggers 41a to 41c wait at a position away from the sheet S being conveyed in the X direction so as not to interfere with the conveyance of the sheet S.

[0038] (3-2) Vertical alignment stage 3(B) shows that the rear end of the first sheet S1 has passed through the nip of the kick-out roller 29, and the leading end of the sheet S1 has reached the vertical alignment roller 40. The sheet S1 abuts against the vertical alignment plate 39 and is aligned based on the position of the vertical alignment plate 39. As the vertical alignment roller 40 continues to rotate, the sheets S2 to S5 which arrive at the vertical alignment roller 40 after the sheet S1 abut against the vertical alignment plate 39 in order. As a result, the five sheets S1 to S5 are aligned in the Y direction (vertical direction) based on the position of the vertical alignment plate 39.

[0039] (3-3) Lateral alignment stage 3C shows that after the alignment of the sheets S1 to S5 in the Y direction (vertical direction) is completed, the alignment in the X direction (horizontal direction) is started. The lateral alignment joggers 41a to 41c are driven in the X direction, which is the alignment direction, to come into contact with the side edges of the sheets S1 to S5 and press the sheets S1 to S5 toward the lateral alignment plates 72a and 72b. Then, the other side edges of the sheets S1 to S5 come into contact with the contact surfaces 300 of the lateral alignment plates 72a and 72b, so that the sheets S1 to S5 are aligned in the X direction (horizontal direction) based on the positions of the lateral alignment plates 72a and 72b.

[0040] (3-4) Adhesion stage (thermocompression stage) 3(D) shows a state where the alignment of the five sheets S1 to S5 in the X and Y directions has been completed. The target position (alignment position) in the alignment operation is the position of the sheet stack W when the adhesive process (thermocompression bonding) is performed by the thermocompression bonding unit 51. As described above, the image forming apparatus 100 applies adhesive toner Tn to the sheets S1 to S5 so that the side on which the adhesive toner image is formed faces the thermocompression bonding unit 51. If the sheet S1 is the cover of a booklet, adhesive toner Tn is not applied.

[0041] The thermocompression bonding unit 51 applies a thermocompression bonding operation to the sheets S1 to S5 for which alignment has been completed. During this time, the lateral alignment joggers 41a to 41c retreat in the -X direction. This allows the intermediate stacking section 42 to be in a state in which it can receive the next plurality of sheets S. After that, the sheet stack W consisting of sheets S6 to S10 generated in the buffer section 80 is stacked on top of the sheets S1 to S5.

[0042] Thereafter, the above-mentioned four steps are repeated for the sheets S1 to S10, so that the sheets S1 to S10 are bonded together in a precisely aligned state.

[0043] As an example, the sheet bundle W is composed of five sheets S. However, the number of sheets S constituting the sheet bundle W may be two or three, etc. In other words, the number of sheets S included in the sheet bundle W may be equal to or less than the maximum number of sheets S that can be stacked in the buffer unit 80.

[0044] (4) Thermocompression unit As shown in FIG. 4A, the thermocompression bonding unit 51 has an adhesive heater 401 with a built-in heating element as a heat source, and an aluminum heating plate 402 arranged thereon. The adhesive heater 401 is, for example, a halogen heater or a ceramic heater. The temperature of the adhesive heater 401 may be measured by a temperature sensor and controlled by a control circuit so that the measured temperature becomes a target temperature. For example, the target temperature is set so that the surface temperature of the pressure applying portion 409 of the heating plate 402 becomes 200° C. By providing the pressure applying portion 409 on the heating plate 402, the heat and pressure of the thermocompression bonding unit 51 are concentrated at the binding position of the sheet stack W. As a result, the efficiency of heating and pressing is improved.

[0045] The adhesive heater 401 is supported by a heater support 403 made of resin. The pressure lever 404 presses the thermocompression bonding unit 51 in the -Z direction (downward) to pressurize the sheet stack W. The pressure of the pressure lever 404 is transmitted to the pressure section 409 via a metal stay 405 as a rigid body. The pressure of the pressure lever 404 can be controlled according to the amount of movement of the pressure lever 404 in the -Z direction (downward). For example, the pressure is 30 kgf.

[0046] The pressure plate 406 is made of an elastic material (e.g., silicone rubber). This is because the pressure plate 406 is a member that can stably receive pressure force. The thermocompression bonding unit 51 presses the sheet stack W1 consisting of sheets S1 to S5, and then separates from the sheet stack W1. Sheets S1 to S5 in FIG. 4A indicate the first to fifth sheets of a booklet as a result. Sheet S1 is the cover of the booklet. Therefore, no image of adhesive toner Tn is formed on sheet S1. An image of adhesive toner Tn is formed on the lower surfaces of the second and subsequent sheets S2 to S5 of the booklet.

[0047] As shown in Fig. 4(B), a sheet bundle W2 is placed on top of the sheets S1 to S5 that have been thermocompression bonded. The sheet bundle W2 is made up of sheets S6 to S10. The thermocompression bonding unit 51 applies a thermocompression bonding operation to the sheet bundle W2 that is placed on the sheet bundle W1. As a result, a booklet made up of many sheets S is produced.

[0048] The sheets S6 to S10 that are stacked later are included in the same booklet as the sheets S1 to S5. Therefore, an image of the adhesive toner Tn is formed on the lower surface of each of the sheets S6 to S10.

[0049] As an example, the post-processing device 130 can create a portion of a booklet consisting of a maximum of 100 sheets S. When booklet creation is started, the buffer section 80 buffers a maximum of five sheets S at a time to create a sheet bundle W, and supplies the sheet bundle W to the intermediate stacking section 42. Each time a sheet bundle W arrives, the thermocompression bonding unit 51 performs a thermocompression operation consisting of a lowering operation, a pressurizing operation, and a lifting operation. By repeating the buffering operation and the thermocompression bonding operation, the productivity of the image forming apparatus 100 is not reduced, and booklets are created efficiently.

[0050] When the thermocompression bonding operation on the sheet stack W including the last page of the booklet is completed in the intermediate stacking section 42, the vertical alignment plate 39 moves from the standby position to the discharge position. In other words, the vertical alignment plate 39 moves in parallel toward the discharge outlet 46, thereby pushing out the completed booklet. Discharge rollers 38 are provided at the discharge outlet 46. When the leading edge of the booklet slightly passes the discharge rollers 38, the vertical alignment plate 39 stops and returns to the standby position again. The discharge rollers 38 discharge the booklet onto the lower tray 37.

[0051] (5) Control system FIG. 5 shows the circuit configuration of the image forming apparatus 100 and the post-processing device 130 in the first embodiment. The AC power source 500 is, for example, a commercial AC power source. The power supplied from the AC power source 500 is supplied to a power supply device 503 and a drive circuit 505 provided in the image forming apparatus 100. The power supplied from the AC power source 500 is also supplied to a drive circuit 511 provided in the post-processing device 130. The power supply device 503 is an AC-DC converter that converts the AC supplied from the AC power source 500 into a DC voltage. Vcc1 is a DC voltage generated by the power supply device 503. The DC voltage Vcc1 is supplied to a motor that drives a conveying roller in the image forming apparatus 100 and a motor that drives a conveying roller in the post-processing device 130. The DCDC converter 504 is a power supply circuit that reduces the DC voltage Vcc1 to generate a DC voltage Vcc2. The DC voltage Vcc2 is supplied to a printer control unit 506 and an option control unit 510 provided in the post-processing device 130.

[0052] Printer control unit 506 is a control circuit that performs overall control of image forming apparatus 100. Printer control unit 506 is connected to drive circuit 505 via control line 551. Printer control unit 506 controls drive circuit 505 via control line 551. For example, printer control unit 506 sends a control signal to drive circuit 505 so that the temperature detected by temperature sensor 63 becomes a target temperature. Drive circuit 505 controls the power supplied from AC power supply 500 to fixing heater 62 based on the control signal supplied from printer control unit 506. Drive circuit 505 is a switching circuit that includes, for example, a triac or the like that can turn AC on and off.

[0053] The detection circuit 502 is a circuit that detects an AC current (inlet current) input from the inlet 501. The inlet 501 may include, for example, a power plug that is inserted into an outlet of the AC power supply 500, and a power cable that is connected to the power plug.

[0054] The printer control unit 506 communicates with the option control unit 510 via a communication line 552. For example, the printer control unit 506 transmits a booklet production instruction (such as the number of sheets S forming the booklet) to the option control unit 510. The printer control unit 506 transmits a drive instruction for the adhesive heater 401 to the option control unit 510.

[0055] The option control unit 510 controls the drive circuit 511 based on a control instruction from the printer control unit 506. Based on the control instruction, the drive circuit 511 controls the AC supplied from the AC power source 500 to the adhesive heater 401 so that the temperature detected by the temperature sensor 512 becomes the target temperature. The drive circuit 511 is also a switching circuit including a triac or the like that can turn the AC on and off. The option control unit 510 supplies a control signal to the drive circuit 511 via a signal line 553.

[0056] (6) Heater power control The rated current that can be taken out from the power outlet (outlet) of the AC power supply 500 is regulated by the laws and regulations of each country (e.g., the Electrical Appliance and Material Safety Act (PSE standard) in Japan, the EN standard in Europe, the UL standard in the United States, etc.). For example, the rated current (hereinafter referred to as the standard value) supplied to an electrical appliance such as the image forming apparatus 100 is 15 A (amperes). Therefore, the image forming apparatus 100 needs to be designed and controlled so that the inlet current Iin does not exceed the standard value Ipse.

[0057] 6A shows an example in which power control is performed on the fixing heater 62 and the adhesive heater 401 without taking into account the standard value Ipse. The process changes over time as follows.

[0058] At time t1, the image forming apparatus 100 and the post-processing apparatus 130 start a printing operation. The printer control unit 506 starts supplying power to the fixing heater 62 and starts conveying the sheet S. Iin is an inlet current. The heater current Ih1 is a current flowing through the fixing heater 62. The heater current Ih2 is a current flowing through the adhesive heater 401.

[0059] At time t2, the printer control unit 506 sends an instruction to the option control unit 510 to start supplying power to the adhesive heater 401. The option control unit 510 starts supplying power to the adhesive heater 401 based on this instruction.

[0060] At time t3, the inlet current Iin exceeds the standard value Ipse. To start the adhesive heater 401, a large heater current Ih2 needs to flow.

[0061] At time t4, the sheet S arrives at the fixing unit 6. Therefore, the printer control unit 506 controls the heater pole Ih1 so that the temperature of the fixing heater 62 reaches the target temperature by time t4.

[0062] At time t5, the inlet current Iin falls below the standard value Ipse. This is due to a decrease in both the heater current Ih1 and the heater current Ih2.

[0063] At time t6, the thermocompression bonding unit 51 performs a thermocompression process on the sheet stack W.

[0064] In this way, the temperature of the fixing heater 62 must reach the target temperature by time t4. Furthermore, the temperature of the adhesive heater 401 must also reach the target temperature by time t6. Therefore, at time t2, the printer control unit 506 starts supplying power to the adhesive heater 401. After time t2, power is supplied to both the fixing heater 62 and the adhesive heater 401. Here, for simplicity of explanation, it is assumed that the inlet current Iin is the sum of the heater current Ih1 and the heater current Ih2. However, in reality, the inlet current Iin also includes the current used by the power supply device 503.

[0065] In general, the lower the heater temperature, the smaller the heater resistance value. Therefore, the lower the heater temperature, the larger the heater current. When the image forming apparatus 100 is started after being stopped for a long time in a low-temperature environment, the inlet current Iin may exceed the standard value Ipse (=15 A) during the period from time t3 to time t5.

[0066] The following method can be considered as a solution to this problem. When a print mode using a post-processing device 130 with high power consumption is specified by the user, the printer control unit 506 suppresses the power supplied to the fixing heater 62 and delays the start of printing so that the inlet current In does not exceed the standard value Ipse. The start of printing is delayed because suppressing the power supplied to the fixing heater 62 increases the time required for the temperature of the fixing heater 62 to reach the target temperature. As another method, the printer control unit 506 monitors the inlet current Iin and determines whether the inlet current Iin is likely to exceed the standard value Ipse. If there is a risk that the inlet current Iin will exceed the standard value Ipse, the printer control unit 506 suppresses the power supplied to the fixing heater 62 and temporarily suspends the printing operation or slows down the printing speed.

[0067] However, when the adhesive heater 401 for producing a booklet is present as in the first embodiment, simply suppressing the power supply to the fixing heater 62 would result in a significant increase in printing time.

[0068] Fig. 6(B) shows the inlet current Iin and the heater currents Ih1 and Ih2 in Example 1. The heater current Ih2 is shown by a solid line and a dashed line, where the solid line shows the heater current Ih2 in Example 1 (power supply limited mode) and the dashed line shows the heater current Ih2 in Fig. 6(A) (normal mode).

[0069] In the first embodiment, the inlet current Iin is prevented from exceeding the standard value Ipse, while the increase in printing time is suppressed. As shown in FIG. 6B, the printer control unit 506 adjusts the power supplied to at least the adhesive heater 401 based on the inlet current Iin detected by the detection circuit 502.

[0070] Specifically, the printer control unit 506 monitors the inlet current Iin detected by the detection circuit 502 and determines whether the inlet current Iin exceeds the first threshold Ith1. In this example, the inlet current Iin reaches the first threshold Ith1 at time t3. The first threshold Ith1 is smaller than the standard value Ipse. For example, the first threshold Ith1 is determined by subtracting a predetermined margin from the standard value Ipse. The predetermined margin is determined by experiment or simulation. When the inlet current Iin becomes equal to or greater than the first threshold Ith1, the printer control unit 506 instructs the option control unit 510 to limit the power supplied to the adhesive heater 401. Upon receiving this instruction, the option control unit 510 controls the drive circuit 511 to limit the power supplied to the adhesive heater 401.

[0071] As the temperature of the fixing heater 62 approaches the target temperature, the power required for the fixing heater 62 decreases. Therefore, the heater current Ih1 of the fixing heater 62 after time t2 becomes smaller than the heater current Ih1 from time t1 to time t2. For example, the printer control unit 506 may transmit the difference dI between the first threshold Ith1 and the heater current Ih1 to the option control unit 510. The option control unit 510 can further increase the heater current Ih2 supplied to the adhesive heater 401 by the difference dI. This causes the inlet current Iin to not exceed the first threshold Ith1 and the standard value Ipse, and the power supplied to the adhesive heater 401 gradually increases in accordance with the decrease in the fixing heater 62 current. In other words, it will be possible to supply power to the adhesive heater 401 to the maximum extent within the range in which the inlet current Iin does not exceed the standard value Ipse.

[0072] At time t5' shown in Fig. 6(B), the printer control unit 506 recognizes that the inlet current Iin falls below the first threshold Ith1 and determines that the risk of the inlet current Iin exceeding the standard value Ipse has decreased. The printer control unit 506 instructs the option control unit 510 to release the power supply limit to the adhesive heater 401. Upon receiving the instruction to release the power supply limit, the option control unit 510 controls the power supply to the adhesive heater 401 so that the temperature of the adhesive heater 401 reaches the target temperature by time t6.

[0073] When the power supply to the adhesive heater 401 is limited, the time required for the temperature of the adhesive heater 401 to reach the target temperature increases. This means that the printing time increases. When a plurality of heaters (the fixing heater 62 and the adhesive heater 401) are arranged upstream and downstream in the conveying path direction of the sheet S as in the first embodiment, a certain amount of time occurs between when the first sheet S passes through the upstream heater and when it reaches the downstream heater. By utilizing this time, the power supply control to the adhesive heater 401, which is the downstream heater, is realized. As described in relation to FIG. 6B, when the heater current Ih1 flowing at the start-up of the fixing heater 62 is large, the power supply to the adhesive heater 401 is suppressed. On the other hand, when the heater current Ih1 decreases, the power supply to the adhesive heater 401 is increased within a range in which the inlet current Iin does not exceed the standard value Ipse. By executing such power supply control, the amount of suppression of the power supply to the adhesive heater 401 is reduced. In this way, the power supply is reduced in the early stage of start-up of the adhesive heater 401 (for example, from time t2 to time t5'), but the power supply is increased in the middle or later stage of start-up of the adhesive heater 401 (from time t5' to time t6). The amount of power (kWh) supplied to the adhesive heater 401 from time t2 to time t6 does not need to change. Therefore, the printing time does not increase, and the temperature of the adhesive heater 401 can reach the target temperature by time t6.

[0074] According to the first embodiment, the image forming system 1 has a fixing heater 62 arranged on the upstream side of the conveying path and an adhesive heater 401 arranged on the downstream side. According to the first embodiment, the current consumption of the entire image forming system 1 is prevented from exceeding the standard value, and an increase in printing time is suppressed.

[0075] In the first embodiment, the power supplied to the fixing heater 62 may be suppressed to the extent that the printing time does not increase. The printer control unit 506 may determine the first threshold Ith1 according to the print mode (e.g., single-sided printing mode, double-sided printing mode, monochrome mode, color mode). The printer control unit 506 may determine the first threshold Ith1 according to the temperature (and humidity) of the environment in which the image forming apparatus 100 is installed. The printer control unit 506 may determine the first threshold Ith1 according to the type of the sheet S (e.g., plain paper, thick paper, thin paper, coated paper). The printer control unit 506 may monitor the transport position of the sheet S by measuring the elapsed time from the start of feeding of the sheet S with a timer. The printer control unit 506 may determine the first threshold Ith1 according to the transport position (elapsed time) of the sheet S.

[0076] The image forming apparatus 100 may be left in an extremely low-temperature environment for a long period of time. As a result, even if the above-described control is performed, the inlet current Iin may exceed the standard value Ipse. In this case, the printer control unit 506 may suppress the power supply to the fixing heater 62. Alternatively, the printer control unit 506 may temporarily suspend the printing operation or reduce the printing speed. Note that the temporary suspension of the printing operation or the reduction in the printing speed may be performed when the inlet current Iin exceeds the standard value Ipse by only limiting the power supply to the fixing heater 62.

[0077] In the first embodiment, the thermocompression bonding unit 51 is disposed in the post-processing device 130. However, the thermocompression bonding unit 51 may be disposed inside the image forming apparatus 100.

[0078] (7) Functions of the printer control unit 7 shows the functions of the printer control unit 506. As an example, the printer control unit 506 has a CPU 701. The CPU 701 executes a control program stored in the memory 702 to realize various functions. A position monitoring unit 711 monitors the conveying position of the sheet S based on the elapsed time from the time when the feeding of the sheet S is started or the detection results of a plurality of sheet sensors 706 installed on the conveying path. A timer 705 measures the elapsed time from the time when the feeding of the sheet S is started. A threshold determination unit 712 may determine a first threshold Ith1 based on the conveying position of the sheet S. A function or a table for determining the first threshold Ith1 from the conveying position of the sheet S may be stored in the memory 702.

[0079] The threshold determination unit 712 may determine the first threshold Ith1 based on an environmental parameter (e.g., an environmental temperature of the image forming apparatus 100) detected by the environmental sensor 704. A function or a table for determining the first threshold Ith1 from the environmental parameter may be stored in the memory 702.

[0080] The threshold determination unit 712 may determine the first threshold Ith1 based on the type of the sheet S input from the operation unit 703. The first threshold Ith1 associated with each of the multiple types may be stored in the memory 702.

[0081] Alternatively, the first threshold Ith1 may be a fixed value stored in a read-only memory (ROM) area of ​​the memory 702. The threshold determination unit 712 reads out the first threshold Ith1 from the memory 702 and sets it in the determination unit 713.

[0082] The determination unit 713 determines whether the inlet current Iin detected by the detection circuit 502 exceeds the first threshold Ith1. When the inlet current Iin exceeds the first threshold Ith1, the instruction unit 714 transmits an instruction to the option control unit 510 to limit the power supply to the adhesive heater 401. When the inlet current Iin becomes equal to or smaller than the first threshold Ith1, the instruction unit 714 transmits an instruction to the option control unit 510 to release the power supply limit on the adhesive heater 401.

[0083] The heater control unit 715 controls the drive circuit 505 so that the temperature of the fixing heater 62 detected by the temperature sensor 63 reaches a target temperature. The CPU 701 further controls a motor 707 that drives the conveying roller pair 82 that conveys the sheet S. This controls the conveying speed (printing speed) of the sheet S.

[0084] (8) Flowchart 8 shows a power control method for the fixing heater 62 and the adhesive heater 401, which is executed by the CPU 701. When a print instruction is input via the operation unit 703, the CPU 701 executes the following process.

[0085] In S800, the CPU 701 (threshold determination unit 712) sets a first threshold Ith1 in the determination unit 713. The first threshold Ith1 may be read from the memory 702, or may be dynamically determined based on the first threshold Ith1.

[0086] In S801, the CPU 701 (heater control unit 715) turns on the fixing heater 62. For example, the CPU 701 instructs the drive circuit 505 to turn on the fixing heater 62. The CPU 701 outputs a control signal to the drive circuit 505 so that the temperature of the fixing heater 62 detected by the temperature sensor 63 reaches and is maintained at a target temperature.

[0087] In S802, the CPU 701 determines whether a specified timing (e.g., time t2) has arrived. For example, time t2 may be a timing when a predetermined time has elapsed since the time when the print operation started (e.g., time t1). When the specified timing (e.g., time t2) arrives, the CPU 701 proceeds from S802 to S803.

[0088] In S803, the CPU 701 turns on the adhesive heater 401. For example, the CPU 701 (instruction unit 714) instructs the option control unit 510 to turn on the adhesive heater 401. As a result, the option control unit 510 starts supplying power to the adhesive heater 401.

[0089] In S804, the CPU 701 (determination unit 713) determines whether the inlet current Iin exceeds the first threshold Ith1. If the inlet current Iin does not exceed the first threshold Ith1, the CPU 701 proceeds from S804 to S808. If the inlet current Iin exceeds the first threshold Ith1, the CPU 701 proceeds from S804 to S805.

[0090] In S805, the CPU 701 (instruction unit 714) starts limiting the power supply to the adhesive heater 401. The instruction unit 714 transmits a power supply limit instruction to the option control unit 510. In response to this, the option control unit 510 limits the amount of power supply to the adhesive heater 401.

[0091] In S806, the CPU 701 (determination unit 713) determines whether the inlet current Iin has become equal to or less than the first threshold Ith1. If the inlet current Iin is not equal to or less than the first threshold Ith1, the CPU 701 continues the limited state of power supply to the adhesive heater 401. If the inlet current Iin becomes equal to or less than the first threshold Ith1, the CPU 701 proceeds from S806 to S807.

[0092] In S807, the CPU 701 ends the power supply restriction to the adhesive heater 401. For example, the instruction unit 714 transmits a release instruction to the option control unit 510. In response to this, the option control unit 510 releases the power supply restriction to the adhesive heater 401.

[0093] In S808, the CPU 701 determines whether or not the production of the booklet is complete. The completion of the production of the booklet may be, for example, whether or not the production of the booklet is completed when the booklet is discharged to the lower tray 37. If the production of the booklet is not completed, the CPU 701 returns from S808 to S804. If the production of the booklet is completed, the CPU 701 proceeds from S808 to S809.

[0094] In S809, the CPU 701 ends the power supply to the fixing heater 62 and the adhesive heater 401. The heater control unit 715 ends the power supply to the fixing heater 62. The instruction unit 714 instructs the option control unit 510 to end the power supply to the adhesive heater 401. As a result, the option control unit 510 ends the power supply to the adhesive heater 401.

[0095] <Example 2> (1) Basic Concept According to the first embodiment, when the current at the start-up of the fixing heater 62 is large, the power supply to the adhesive heater 401 is suppressed, and when the current at the start-up of the fixing heater 62 decreases, the power supply to the adhesive heater 401 is increased. Also, time t2 in FIG. 6A is the same as time t2 in FIG. 6B. In other words, the timing at which the supply of power to the adhesive heater 401 starts (start timing) has not been adjusted. Therefore, the printer control unit 506 may delay the start timing for the adhesive heater 401 based on the detection result of the inlet current Iin.

[0096] Fig. 9 is a diagram for explaining heater power control in the second embodiment. In Fig. 9, the same reference symbols are used for items common to Fig. 6(A) and Fig. 6(B). In Fig. 9, the control from time t1 to time t2 is the same as the control from time t1 to time t2 in Fig. 6(B).

[0097] At time t2, the CPU 701 determines whether or not to start the power supply to the adhesive heater 401 based on the inlet current Iin detected by the detection circuit 502. For example, the CPU 701 determines whether or not the inlet current Iin exceeds a preset second threshold Ith2. If the inlet current Iin exceeds the second threshold Ith2, and power supply to the adhesive heater 401 is started, the inlet current Iin may exceed the specified value Ispe (=15A). In this case, the CPU 701 delays the timing of power supply to the adhesive heater 401 from time t2 to time t2'. Here, the second threshold Ith2 is smaller than the first threshold Ith1. For example, the second threshold Ith2 may be determined by subtracting the expected maximum current Ih2_max of the adhesive heater 401 from the standard value Ipse or the first threshold Ith1. When the second threshold Ith2 is determined by subtracting the expected maximum current Ih2_max from the first threshold Ith1, the difference between the standard value Ipse and the second threshold Ith2 is greater than the expected maximum current Ih2_max, and as a result, the probability that the inlet current Iin exceeds the standard value Ipse will also decrease.

[0098] At time t2', the heater current Ih1 flowing through the fixing heater 62 decreases, and the inlet current Iin becomes smaller than the second threshold Ith2. Then, the CPU 701 instructs the option control unit 510 to start supplying power to the adhesive heater 401. Based on this instruction, the option control unit 510 starts supplying power to the adhesive heater 401. The option control unit 510 controls the power supplied to the adhesive heater 401 so that the temperature of the adhesive heater 401 reaches the target temperature by time t6.

[0099] As in the first embodiment, the timing to start supplying power to the adhesive heater 401 is delayed by utilizing the transport time from when the first sheet S passes through the fixing heater 62 until it reaches the adhesive heater 401. Note that the time from time t2' to time t6 is shorter than the time from time t2 to time t6, which is the specified timing. Therefore, the power (heater current Ih2 shown by the solid line) supplied to the adhesive heater 401 is increased from the normal power (heater current Ih2 shown by the dashed line). This makes it possible to make the temperature of the adhesive heater 401 reach the target temperature without increasing the printing time.

[0100] (2) Functions of CPU701 FIG. 10 shows functions realized by the CPU 701 of the second embodiment. The threshold determination unit 1012 determines the second threshold Ith2 based on the standard value Ipse and the assumed maximum current Ih2_max stored in the memory 702. If the second threshold Ith2 has already been stored in the memory 702, the threshold determination unit 1012 reads the second threshold Ith2 from the memory 702 and sets it in the judgment unit 1013. If the option control unit 510 has a detection circuit (detection circuit 1202 in FIG. 12) that detects the heater current Ih2, the option control unit 510 reports the heater current Ih2 to the printer control unit 506. When the heater current Ih2 exceeds the existing assumed maximum current Ih2_max, the CPU 701 may update the assumed maximum current Ih2_max stored in the memory 702 with the heater current Ih2.

[0101] The determination unit 1013 determines whether the inlet current Iin exceeds the second threshold Ith2 at time t2. When the inlet current Iin exceeds the second threshold Ith2 at time t2, the instruction unit 1014 delays the transmission of an instruction to turn on the adhesive heater 401 to the option control unit 510. For example, the instruction unit 1014 delays the transmission of an instruction to turn on the adhesive heater 401 to the option control unit 510 until the inlet current Iin falls below the second threshold Ith2 after time t2. When the inlet current Iin falls below the second threshold Ith2 (time t2'), the instruction unit 1014 instructs the option control unit 510 to turn on the adhesive heater 401. At this time, the instruction unit 1014 may instruct the option control unit 510 to increase the power supplied to the adhesive heater 401 more than usual.

[0102] (3) Flowchart Fig. 11 is a flowchart of the second embodiment. The CPU 701 executes the following process according to the control program. In Fig. 11, steps S803 to S807 in Fig. 8 are replaced with steps S1100 and S1101. Therefore, steps S1100 and S1101 will be mainly described. When it is determined in step S802 that the specified timing has arrived, the CPU 701 proceeds from step S802 to step S1100.

[0103] In S1100, the CPU 701 (determination unit 1013) determines whether the inlet current Iin exceeds the second threshold Ith2. If the inlet current Iin exceeds the second threshold Ith2, the CPU 701 delays the timing of starting the power supply to the adhesive heater 401. That is, the CPU 701 waits until the inlet current Iin becomes equal to or less than the second threshold Ith2. When the inlet current Iin becomes equal to or less than the second threshold Ith2, the CPU 701 proceeds from S1100 to S1101. Note that the CPU 701 may set the flag to 1 if the inlet current Iin exceeds the second threshold Ith2 at time t2.

[0104] In S1101, the CPU 701 (instruction unit 1014) instructs the option control unit 510 to turn on the adhesive heater 401. If the flag is 1, the instruction unit 1014 may instruct the option control unit 510 to increase the power supply to the adhesive heater 401. Thereafter, the CPU 701 proceeds from S1101 to S808.

[0105] According to the second embodiment, by delaying the timing at which power supply to the adhesive heater 401 is started, it is possible to prevent the current consumption of the entire printer system from exceeding the standard value and to prevent an increase in printing time.

[0106] Note that there may be cases where the inlet current Iin does not become equal to or less than the second threshold value Ith2 even after a predetermined time has elapsed since time t2. In this case, the CPU 701 may suppress the power supply to the fixing heater 62. Furthermore, the CPU 71 may temporarily suspend the printing operation or reduce the printing speed. Here, the predetermined time is a time determined so that the printing speed (throughput) of the image forming apparatus 100 can achieve a target speed. The throughput is, for example, the number of sheets S that can be printed per unit time.

[0107] The CPU 701 may determine the time difference (delay time) between time t2 and time t2' from the difference between the inlet current Iin and the second threshold Ith2 at time t2. In this case, when time t2' arrives, the CPU 701 may instruct the option control unit 510 to supply power to the adhesive heater 401 without checking the inlet current Iin. The larger the difference between the inlet current Iin and the second threshold Ith2, the longer the delay time. The smaller the difference between the inlet current Iin and the second threshold Ith2, the shorter the delay time.

[0108] <Example 3> (1) Basic Concept The main parts of the third embodiment are similar to those of the first embodiment. Therefore, the same reference numerals are given to the same matters in the third embodiment as those in the first embodiment, and the description thereof will be omitted.

[0109] 12 shows the circuit configuration of the image forming apparatus 100 and the post-processing device 130 in the third embodiment. The post-processing device 130 includes a power supply device 1201 and a detection circuit 1202. The detection circuit 1202 detects the heater current Ih2 flowing to the adhesive heater 401.

[0110] The AC voltage input to the post-processing device 130 is applied to the power supply device 1201 via a path separate from the path to the drive circuit 511 and the detection circuit 1202. The power supply device 1201 is an AC / DC converter, and converts the input AC voltage into a DC voltage Vc3. In the first embodiment, the operating voltage of the motor and the like provided in the post-processing device 130 is the DC voltage Vcc1 generated by the power supply device 503. In the third embodiment, the DC voltage Vcc3 generated by the power supply device 1201 is supplied to the motor and the like provided in the post-processing device 130. This makes it possible to reduce the output power capacity of the power supply device 503 disposed in the image forming apparatus 100. As a result, the manufacturing cost of the power supply device 503 is reduced. The third embodiment will be effective when the cost of the power supply device 503 in the first embodiment is higher than the costs of the power supply device 503 and the power supply device 1201 in the third embodiment.

[0111] The detection circuit 1202 transmits the detection result of the heater current Ih2 flowing through the adhesive heater 401 to the option control unit 510. The option control unit 510 transmits the detection result of the heater current Ih2 to the printer control unit 506 via the communication line 552.

[0112] In FIG. 6B, the power supply to the adhesive heater 401 was suppressed based on the inlet current information Iin, but the proportion of the heater current Ih2 to the inlet current Iin was unknown. As described in the first embodiment, the inlet current Iin also includes the current used by the power supply device 503. Therefore, when the post-processing device 130 also includes the power supply device 1201 as in the third embodiment, the total value of the currents used by the power supply device 503, the power supply device 1201, the fixing heater 62, and the adhesive heater 401 becomes the inlet current Iin. If the proportion F of the heater current Ih2 in the inlet current Iin is small, it may not be possible to suppress the inlet current Iin to the standard value Ipse or less by simply suppressing the power supply to the adhesive heater 401. In that case, the printer control unit 506 needs to suppress the power supply to the fixing heater 62, temporarily suspend the printing operation, or reduce the printing speed.

[0113] However, there is a restriction on the timing at which the conveyance of the sheet S can be stopped or the conveyance speed can be reduced. If the power supply to the fixing heater 62 is suppressed, it takes longer for the temperature of the fixing heater 62 to reach the target temperature. Therefore, the conveyance control must be changed at a timing before the sheet S reaches the fixing device 6. Furthermore, if the conveyance control is changed while the toner image is being transferred from the transfer belt 3 to the sheet S, the quality of the image formed on the sheet S may be reduced. Therefore, changing the conveyance control at such a timing should be avoided. Therefore, the determination of whether to change the conveyance control should be made as early as possible after the start of the printing operation. This will ensure a sufficient period during which the conveyance control of the sheet S can be changed.

[0114] In the third embodiment, the printer control unit 506 determines whether to change the transport control based on the inlet current Iin and the heater current Ih2 of the adhesive heater 401 detected by the detection circuit 1202. The printer control unit 506 obtains the ratio F of the heater current Ih2 in the inlet current Iin, and determines whether this ratio F is smaller than a threshold value Fth. If this ratio F is smaller than the threshold value Fth, the inlet current Iin will exceed the standard value Ipse even if the power supplied to the adhesive heater 401 is reduced. Therefore, the printer control unit 506 reduces the power supplied to the fixing heater 62, temporarily suspends the printing operation, or reduces the printing speed.

[0115] This allows the determination of whether or not to change the transport control to be executed at an earlier timing. A sufficient period of time is secured to change the transport control of the sheet S, and the quality of the image formed on the sheet S is maintained. Furthermore, the inlet current Iin is suppressed to be less than the standard value Ipse.

[0116] Incidentally, in the already described second embodiment, the second threshold value Ith2 is determined by subtracting the expected maximum current Ih2_max from the standard value Ipse. The heater current Ih2 changes depending on the temperature of the adhesive heater 401. Therefore, if the actual heater current Ih2 is less than the expected maximum current Ih2_max, the timing of supplying power to the adhesive heater 401 may be unnecessarily delayed.

[0117] Therefore, the detection circuit 1202 may be added to the second embodiment. The CPU 701 may adjust the curve of the power supplied from time t2' to time t6 based on the actual heater current Ih2. This will prevent the time required for the temperature of the adhesive heater 401 to reach the target temperature from being unnecessarily long.

[0118] According to the third embodiment, the CPU 701 can more accurately determine whether the inlet current Iin is likely to exceed the standard value Ipse by considering both the inlet current Iin and the heater current Ih2 of the adhesive heater 401. As a result, the CPU 701 can more accurately and earlier determine whether an increase in printing time is necessary. This makes it possible to suppress the inlet current Iin to be equal to or lower than the standard value Ipse while maintaining image quality. It also makes it possible to suppress an increase in printing time.

[0119] (2) CPU Functions 13 shows functions realized by the CPU 701 in the third embodiment. Note that the description of the matters described in the first embodiment will be omitted.

[0120] The calculation unit 1301 calculates the ratio F of the heater current Ih2 detected by the detection circuit 1202 to the inlet current Iin detected by the detection circuit 502. The judgment unit 1302 judges whether the ratio F is less than a threshold value Fth. The threshold value Fth is determined in advance by an experiment or a simulation, and is stored in the ROM area of ​​the memory 702. If the ratio F is less than the threshold value Fth, the inlet current Iin may exceed the standard value Ipse even if the heater current Ih2 to the adhesive heater 401 is adjusted. Therefore, the motor control unit 1303 controls the motor 707 to continuously suspend the printing operation, or controls the motor 707 to reduce the printing speed.

[0121] (3) Flowchart Fig. 14 shows power supply control executed by the CPU 701 in the embodiment 3. Fig. 14 differs from Fig. 8 in that if the result in S806 is No, the CPU 701 proceeds from S806 to S1401.

[0122] In S1401, the CPU 701 (calculation unit 1301) calculates the proportion F of the heater current Ih2 in the inlet current Iin. In S1402, the CPU 701 (determination unit 1302) determines whether the proportion F is less than a threshold value Fth. If the proportion F is equal to or greater than the threshold value Fth, the CPU 701 returns from S1402 to S805 and continues limiting the power supply to the adhesive heater 401. On the other hand, if the proportion F is less than the threshold value Fth, the effect of limiting the power supply to the adhesive heater 401 with respect to the inlet current Iin is small. Therefore, the CPU 701 proceeds from S1402 to S1403.

[0123] In S1403, the CPU 701 (motor control unit 1303) changes the transport control of the sheet S. For example, the motor control unit 1303 controls the motor 707 to continuously suspend the printing operation, or controls the motor 707 to reduce the printing speed. This prevents the inlet current Iin from exceeding the standard value Ipse. The CPU 701 may also reduce the power (heater current Ih1) supplied to the fixing heater 62 while changing the transport control. For example, the CPU 701 may change the transport control when the inlet current Iin still exceeds the first threshold value Ith1 even after reducing the heater current Ih1.

[0124] <Technical ideas derived from examples> (Item 1) An image forming means (e.g., image forming unit 10) that forms an image on a sheet using toner; a fixing means (e.g., a fixing device 6) having a first heater (e.g., a fixing heater 62) for fixing the image on the sheet; a booklet-making unit (e.g., post-processing device 130, thermocompression bonding unit 51) that heats and bonds the sheets that have passed through the fixing unit with a second heater (e.g., bonding heater 401) to make a booklet; an inlet (inlet 501) for supplying power to the first heater and the second heater; A first detection means (e.g., a detection circuit 502) for detecting an inlet current flowing through the inlet; a control unit (e.g., a printer control unit 506) that controls the power supplied from the inlet to the first heater and the second heater; The control means adjusts the power supplied to the second heater based on the inlet current detected by the first detection means so that the inlet current does not exceed a rated value (e.g., standard value Ipse), in an image forming apparatus.

[0125] According to the first to third embodiments, at least the heater current Ih2 is controlled so that the inlet current Iin does not exceed the standard value Ipse. This makes it difficult for the current consumption in the image forming apparatus 100, which heats and bonds a plurality of sheets S with a heater to produce a booklet, to exceed the rated value (standard value Ipse).

[0126] (Item 2) The control means 2. The image forming apparatus according to item 1, wherein, when the inlet current exceeds a first threshold value (e.g., Ith1) that is smaller than the rated value, the power supplied to the second heater is reduced so that the inlet current does not exceed the rated value.

[0127] As described in the first and third embodiments, when the inlet current Iin exceeds the first threshold Ith1, at least the heater current Ih2 may be temporarily reduced, so that the inlet current Iin may be maintained below the standard value Ipse.

[0128] (Item 3) The control means 3. The image forming apparatus according to item 1 or 2, wherein, when the inlet current exceeds a first threshold value that is smaller than the rated value, a timing of supplying power to the second heater is adjusted so that the inlet current does not exceed the rated value.

[0129] As described in the first to third embodiments, the timing of supplying power to the adhesive heater 401 may be adjusted. This allows the inlet current Iin to be maintained below the standard value Ipse. Note that, as illustrated in FIG. 6B, reducing the power in the first period and increasing the power in the second period also corresponds to adjusting the timing of supplying power.

[0130] (Item 4) 4. The image forming apparatus according to item 3, wherein adjusting the timing of supplying power to the second heater includes delaying the timing of supplying power to the second heater.

[0131] 9, the CPU 701 may delay the timing of supplying power to the adhesive heater 401. This may keep the inlet current Iin below the standard value Ipse.

[0132] (Item 5) The control means 5. The image forming apparatus according to any one of items 1 to 4, wherein, when the inlet current exceeds a first threshold value that is smaller than the rated value, both the power supplied to the first heater and the power supplied to the second heater are adjusted so that the inlet current does not exceed the rated value.

[0133] As mentioned in the first and third embodiments, both the heater current Ih1 and the heater current Ih2 may be adjusted to maintain the inlet current Iin below the standard value Ipse.

[0134] (Item 6) Further comprising a second detection means (e.g., detection circuit 1202) for detecting a heater current (e.g., Ih2) flowing through the second heater, 6. The image forming apparatus according to any one of items 1 to 5, wherein the control means adjusts the power supplied to at least the second heater based on the inlet current and the heater current detected by the second detection means so that the inlet current does not exceed the rated value.

[0135] As suggested in the second and third embodiments, the CPU 701 may adjust the power to the adhesive heater 401 by taking into consideration both the inlet current Iin and the heater current Ih2. For example, the ratio F of the heater current Ih2 to the inlet current Iin may be taken into consideration. Also, the second threshold Ith2 may be determined based on the maximum value (e.g., Ih2_max) of the heater current Ih2 measured in the past, and the adhesive heater 401 may be controlled based on the second threshold Ith2. This may maintain the inlet current Iin below the standard value Ipse.

[0136] (Item 7) The image forming apparatus according to item 6, wherein the control means delays the timing of supplying power to at least the second heater based on the inlet current and the heater current detected by the second detection means (e.g., detection circuit 1202) so that the inlet current does not exceed the rated value.

[0137] As suggested in the second and third embodiments, the CPU 701 may delay the timing of supplying power to the adhesive heater 401. In this manner, the power supply limit may include both a quantitative limit and a time limit of the power. This may keep the inlet current Iin below the standard value Ipse.

[0138] (Item 8) Further comprising a second detection means (e.g., detection circuit 1202) for detecting a heater current flowing through the second heater, The image forming apparatus described in item 1, wherein the control means reduces both the power supplied to the first heater and the power supplied to the second heater when the proportion (e.g., F) of the heater current detected by the second detection means in the inlet current is smaller than a predetermined value (e.g., Fth).

[0139] As suggested in the third embodiment, the CPU 701 may reduce both the power of the fixing heater 62 and the power of the adhesive heater 401. This may keep the inlet current Iin below the standard value Ipse.

[0140] (Item 9) Further, the sheet is conveyed to the image forming means by a conveying means (e.g., a motor 707). 9. The image forming apparatus according to item 8, wherein the control unit further reduces a conveying speed (e.g., a printing speed) of the sheet when the ratio is smaller than the predetermined value.

[0141] As suggested in the third embodiment, the CPU 701 may reduce the printing speed when the ratio F is too small, thereby keeping the inlet current Iin below the standard value Ipse.

[0142] (Item 10) a first storage means (e.g., memory 702) for storing a second threshold value (e.g., Ith2) smaller than the rated value; 2. The image forming apparatus according to item 1, wherein the control unit starts supplying power to the second heater when the inlet current drops to or below the second threshold after the inlet current exceeds the second threshold.

[0143] As illustrated in FIG. 9, when the inlet current Iin exceeds the second threshold Ith2, the CPU 701 may wait until the inlet current Iin falls to or below the second threshold Ith2.

[0144] (Item 11) 11. The image forming apparatus according to item 10, wherein the difference between the rated value and the second threshold value is equal to or greater than a maximum current flowing through the second heater.

[0145] In the second embodiment, a case has been introduced in which the difference between the standard value Ipse and the second threshold Ith2 is the expected maximum current Ih2_max. However, taking into consideration a further margin, this difference may be set to be greater than the expected maximum current Ih2_max. For example, the difference between the first threshold Ith1 and the second threshold Ith2 may be the expected maximum current Ih2_max.

[0146] (Item 12) A second detection means (e.g., detection circuit 1202) for detecting a current flowing through the second heater; and a second storage means (e.g., memory 702) for storing the maximum current flowing through the second heater detected by the second detection means, Item 12. The image forming apparatus according to item 11, wherein the control unit updates the second threshold value based on the maximum current and the rated value stored in the second storage unit.

[0147] As suggested in the second embodiment, the CPU 701 may obtain the heater current Ih2 by the detection circuit 1202 described in the third embodiment. When the heater current Ih2 is greater than the assumed maximum current Ih2_max stored in the memory 702, the CPU 701 updates the assumed maximum current Ih2_max with the heater current Ih2. Furthermore, the CPU 701 may update the second threshold Ith2 based on the specified value Ipse and the updated assumed maximum current Ih2_max. This allows the inlet current Iin to be maintained below the standard value Ipse even in the image forming apparatus 100 left in a low-temperature environment.

[0148] (Item 13) The image forming apparatus according to any one of items 2 to 5, wherein the control means determines the first threshold value according to a print mode applied to the image forming means, a temperature of an environment in which the image forming apparatus is installed, or a type of the sheet.

[0149] As mentioned in the first embodiment, the first threshold value may be determined according to the print mode, the environmental temperature, or the type of the sheet S. Thus, the first threshold value Ith1 will be set to an appropriate value according to the print mode, the environmental temperature, or the type of the sheet S.

[0150] (Item 14) The image forming apparatus further includes a timer (e.g., a timer 705) for measuring the elapsed time from the start of a printing operation, 6. The image forming apparatus according to any one of items 2 to 5, wherein the control unit determines the first threshold value in accordance with the elapsed time.

[0151] As mentioned in the first embodiment, the first threshold Ith1 may be determined according to the elapsed time from the start of the printing operation.

[0152] (Item 15) A feeding means (e.g., a feeding roller 81) for feeding the sheet to a conveying path; a monitoring unit (e.g., a position monitoring unit 711) that monitors a conveying position of the sheet that is fed to the conveying path by the feeding unit and conveyed along the conveying path, 6. The image forming apparatus according to any one of items 2 to 5, wherein the control unit determines the first threshold value in accordance with the transport position of the sheet.

[0153] As mentioned in the first embodiment, the first threshold Ith1 may be determined depending on the transport position of the sheet S.

[0154] (Item 16) 2. The image forming apparatus according to claim 1, wherein the control unit reduces the amount of power supplied to the first heater when adjusting only the amount or timing of power supply to the second heater would cause the inlet current to exceed the rated value.

[0155] As mentioned in the first and third embodiments, if the inlet current Iin exceeds the standard value Ipse even when the power to the adhesive heater 401 is reduced, the power to the fixing heater 62 may also be reduced. This may reliably maintain the inlet current Iin below the standard value Ipse.

[0156] (Item 17) 17. The image forming apparatus according to item 16, wherein the control unit adjusts the amount or timing of power supply to the second heater, and reduces the conveying speed of the sheet when the inlet current exceeds the rated value even if the amount of power supply to the first heater is reduced.

[0157] As mentioned in the first to third embodiments, the CPU 701 first imposes a power supply limit on the adhesive heater 401. If this is insufficient, the CPU 701 also imposes a power supply limit on the fixing heater 62. If this is insufficient, the CPU 701 may control the motor 707 to reduce the conveying speed of the sheet S. This may reliably maintain the inlet current Iin below the standard value Ipse.

[0158] (Item 18) Item 18. The image forming apparatus according to item 17, wherein reducing the conveying speed of the sheet includes temporarily interrupting image formation on the sheet.

[0159] The CPU 701 may control the motor 707 to set the conveying speed of the sheet S to zero in order to temporarily halt image formation on the sheet S. This will reliably maintain the inlet current Iin below the standard value Ipse.

[0160] (Item 19) 2. The image forming apparatus according to item 1, wherein the control means has a first supply mode in which the power supplied to the second heater is rapidly increased and a second supply mode in which the power supplied to the second heater is gradually increased, and controls the second heater in the first supply mode if the inlet current does not exceed a first threshold value which is smaller than the rated value, and controls the second heater in the second supply mode if the inlet current exceeds the first threshold value.

[0161] As shown in FIG. 6B, the heater current Ih2 indicated by the dashed line corresponds to the CPU 701 executing the first supply mode. The heater current Ih2 indicated by the solid line corresponds to the CPU 701 executing the second supply mode. If the inlet current Iin does not exceed the first threshold Ith1, the CPU 701 controls the adhesive heater 401 in the first supply mode. If the inlet current Iin exceeds the first threshold, the CPU 701 controls the adhesive heater 401 in the second supply mode. This will keep the inlet current Iin below the standard value Ipse.

[0162] (Item 20) The control means A first control unit (e.g., a printer control unit 506, a drive circuit 505) that controls the power supplied to the first heater; A second control unit (e.g., an optional control unit 510, a drive circuit 511) that controls the power supplied to the second heater, 20. The image forming apparatus according to any one of items 1 to 19, wherein, when the inlet current detected by the first detection means exceeds a first threshold value, the first control unit instructs the second control unit to adjust the supply of power to the second heater, thereby preventing the inlet current from exceeding the rated value.

[0163] In this manner, a plurality of heaters may be controlled by a plurality of controllers working together.

[0164] (Item 21) Instructing to adjust the supply of power to the second heater comprises: Adjusting the amount of power supplied to the second heater (e.g., heater current Ih2); and delaying a timing for starting the supply of power to the second heater.

[0165] As mentioned in the first to third embodiments, the power supply limit of the adhesive heater 401 is realized by either limiting the amount of the heater current Ih2 or limiting the amount of the heater current Ih2 over time. This may be realized by reducing the slope of the heater current Ih2.

[0166] (Item 22) The booklet creation means includes: A stacking means (e.g., a sheet cassette 8) for stacking the plurality of sheets; the second heater for heating an adhesive toner image formed on any one of the plurality of sheets stacked on the stacking means; A pressing means (e.g., a pressing unit 409) for pressing the plurality of sheets; 22. The image forming apparatus according to any one of items 1 to 21, comprising:

[0167] (Item 23) An image forming system having an image forming apparatus and a post-processing apparatus detachable from the image forming apparatus, The image forming apparatus includes: an image forming means for forming an image on a sheet using toner; a fixing means having a first heater for fixing the image on the sheet, The post-treatment device includes: a booklet making means for making a booklet by heating and bonding the plurality of sheets that have passed through the fixing means by a second heater, The image forming apparatus further comprises: an inlet for supplying power to the first heater and the second heater; A first detection means for detecting an inlet current flowing through the inlet; a control means for controlling the power supplied from the inlet to the first heater and the second heater, The control unit adjusts the power supplied to the second heater based on the inlet current detected by the first detection unit so that the inlet current does not exceed a rated value.

[0168] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0169] 10: image forming section, 3: fixing device, 51: thermocompression unit, 501: inlet, 502: detection circuit, 506: printer control section, 510: option control section

Claims

1. an image forming means for forming an image on a sheet using toner; a fixing means having a first heater for fixing the image onto the sheet; a booklet producing means for producing a booklet by heating and bonding the plurality of sheets that have passed through the fixing means by a second heater; an inlet for supplying power to the first heater and the second heater; A first detection means for detecting an inlet current flowing through the inlet; a control means for controlling the power supplied from the inlet to the first heater and the second heater, The control unit adjusts the power supplied to the second heater based on the inlet current detected by the first detection unit so that the inlet current does not exceed a rated value.

2. The control means The image forming apparatus according to claim 1 , wherein when the inlet current exceeds a first threshold value that is smaller than the rated value, the power supplied to the second heater is reduced so that the inlet current does not exceed the rated value.

3. The control means The image forming apparatus according to claim 1 , wherein when the inlet current exceeds a first threshold value that is smaller than the rated value, a timing of supplying power to the second heater is adjusted so that the inlet current does not exceed the rated value.

4. The image forming apparatus according to claim 3 , wherein adjusting the timing of supplying power to the second heater includes delaying the timing of supplying power to the second heater.

5. The control means 2. The image forming apparatus of claim 1, wherein when the inlet current exceeds a first threshold value that is smaller than the rated value, both the power supplied to the first heater and the power supplied to the second heater are adjusted so that the inlet current does not exceed the rated value.

6. Further, a second detection means is provided for detecting a heater current flowing through the second heater, 2. The image forming apparatus according to claim 1, wherein the control means adjusts the power supplied to at least the second heater based on the inlet current and the heater current detected by the second detection means so that the inlet current does not exceed the rated value.

7. 7. The image forming apparatus according to claim 6, wherein the control means delays the timing of supplying power to at least the second heater based on the inlet current and the heater current detected by the second detection means so that the inlet current does not exceed the rated value.

8. Further, a second detection means is provided for detecting a heater current flowing through the second heater, 2. The image forming apparatus according to claim 1, wherein the control means reduces both the power supplied to the first heater and the power supplied to the second heater when the proportion of the heater current detected by the second detection means in the inlet current is smaller than a predetermined value.

9. a conveying means for conveying the sheet to the image forming means, 9. The image forming apparatus according to claim 8, wherein the control unit further reduces the conveying speed of the sheet when the ratio is smaller than the predetermined value.

10. a first storage means for storing a second threshold value smaller than the rated value; 2 . The image forming apparatus according to claim 1 , wherein the control unit starts supplying power to the second heater when the inlet current exceeds the second threshold and then drops to or below the second threshold.

11. The image forming apparatus according to claim 10 , wherein the difference between the rated value and the second threshold value is equal to or greater than a maximum current flowing through the second heater.

12. A second detection means for detecting a current flowing through the second heater; a second storage means for storing the maximum current flowing through the second heater detected by the second detection means, The image forming apparatus according to claim 11 , wherein the control unit updates the second threshold value based on the maximum current and the rated value stored in the second storage unit.

13. 6. The image forming apparatus according to claim 2, wherein the control means determines the first threshold value according to a print mode applied to the image forming means, a temperature of the environment in which the image forming apparatus is installed, or a type of the sheet.

14. a timer for measuring an elapsed time from the start of a printing operation in the image forming apparatus; The image forming apparatus according to claim 2 , wherein the control unit determines the first threshold value in accordance with the elapsed time.

15. A feeding means for feeding the sheet to a conveying path; a monitoring unit that monitors a conveying position of the sheet that is fed to the conveying path by the feeding unit and conveyed along the conveying path, The image forming apparatus according to claim 2 , wherein the control unit determines the first threshold value in accordance with the transport position of the sheet.

16. 2. The image forming apparatus according to claim 1, wherein the control unit reduces the amount of power supplied to the first heater when adjusting only the amount or timing of power supply to the second heater causes the inlet current to exceed the rated value.

17. 17. The image forming apparatus according to claim 16, wherein the control unit adjusts the amount or timing of power supply to the second heater, and reduces the conveying speed of the sheet when the inlet current exceeds the rated value even when the amount of power supply to the first heater is reduced.

18. The image forming apparatus according to claim 17 , wherein the step of reducing the conveying speed of the sheet includes temporarily suspending image formation on the sheet.

19. 2. The image forming apparatus according to claim 1, wherein the control means has a first supply mode in which the power supplied to the second heater is suddenly increased and a second supply mode in which the power supplied to the second heater is gradually increased, and controls the second heater in the first supply mode if the inlet current does not exceed a first threshold value which is smaller than the rated value, and controls the second heater in the second supply mode if the inlet current exceeds the first threshold value.

20. The control means A first control unit that controls power supplied to the first heater; A second control unit that controls the power supplied to the second heater, 2. The image forming apparatus according to claim 1, wherein when the inlet current detected by the first detection means exceeds a first threshold value, the first control unit instructs the second control unit to adjust the supply of power to the second heater, thereby preventing the inlet current from exceeding the rated value.

21. Instructing to adjust the supply of power to the second heater comprises: adjusting an amount of power supplied to the second heater; and delaying a timing for starting the supply of power to the second heater.

22. The booklet creation means includes: A stacking means for stacking the plurality of sheets; the second heater for heating an adhesive toner image formed on any one of the plurality of sheets stacked on the stacking means; a pressing means for pressing the plurality of sheets; The image forming apparatus according to claim 1 .

23. An image forming system having an image forming apparatus and a post-processing apparatus detachable from the image forming apparatus, The image forming apparatus includes: an image forming means for forming an image on a sheet using toner; a fixing means having a first heater for fixing the image on the sheet, The post-treatment device includes: a booklet making means for making a booklet by heating and bonding the plurality of sheets that have passed through the fixing means by a second heater, The image forming apparatus further comprises: an inlet for supplying power to the first heater and the second heater; A first detection means for detecting an inlet current flowing through the inlet; a control means for controlling the power supplied from the inlet to the first heater and the second heater, The control unit adjusts the power supplied to the second heater based on the inlet current detected by the first detection unit so that the inlet current does not exceed a rated value.

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