Image forming system, control device and program

Abstract

To reduce power consumption while ensuring productivity and fixability.SOLUTION: An image forming system 10 comprises: a first fixing unit 160 that fixes a first toner image formed on a sheet S; and a second fixing unit 230 that fixes a second toner image formed on the sheet S, and the image forming system comprises: a first determination unit (control unit 101) that determines a first standby temperature that is the temperature of the first fixing unit 160 in a standby state; and a second determination unit (control unit 201) that determines a second standby temperature that is the temperature of the second fixing unit 230 in a standby state. At a temperature lower than a first fixable temperature and at a timing when the sheet S reaches the first fixing unit 160, the first determination unit determines the first standby temperature so that the temperature of the first fixing unit 160 becomes the first fixable temperature. At a temperature lower than a second fixable temperature and at a timing when the sheet S reaches the second fixing unit 230, the second determination unit determines the second standby temperature so that the temperature of the second fixing unit 230 becomes the second fixable temperature.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming system, a control device, and a program. [Background technology]

[0002] In recent years, serial tandem image forming systems have been put to practical use, in which two image forming apparatuses are connected in series to perform double-sided printing, etc. For example, an image forming apparatus in a front stage (a front-stage machine) forms a toner image on a first side (e.g., the front side) of a sheet of paper, and an image forming apparatus in a rear stage (a rear-stage machine) forms a toner image on a second side (e.g., the back side) of the sheet of paper. This allows for improved productivity compared to double-sided printing performed with a single image forming apparatus. Such serial tandem image forming systems are generally applied to production print machines that pursue high productivity.

[0003] In such an image forming system, each of the upstream and downstream machines is provided with a fixing section that fixes the toner image onto the paper. In this regard, Patent Document 1 describes an image forming system that controls target values ​​of temperatures of fixing units in a preceding stage machine and a succeeding stage machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-108273 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in an image forming system in which a fixing unit is provided in each of a front-stage machine and a rear-stage machine, there is a problem in that power consumption is high due to the two fixing units. In Patent Document 1, although power consumption can be reduced by lowering the target temperature of the fixing unit, there is a risk that fixability cannot be ensured if the temperature of the fixing unit during fixing is lowered. In addition, power consumption can be reduced by lowering the temperature of the fixing unit during standby when not fixing, but if the temperature of the fixing unit is lowered too much, it will take a long time for the fixing unit to heat up to a temperature suitable for fixing when printing begins, and there is a risk that productivity will not be ensured.

[0006] An object of the present invention is to provide an image forming system, a control device, and a program that can reduce power consumption while ensuring productivity and fixability. [Means for solving the problem]

[0007] In order to solve the above problem, the image forming system of the invention described in claim 1 comprises: a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; An image forming system comprising: a first determination unit that determines a first standby temperature, which is the temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; a first acquisition unit that acquires a first paper conveyance distance, which is a distance from a reference position to when the paper reaches the first fixing unit; a second acquisition unit that acquires a second paper conveyance distance, which is a distance from the reference position to when the paper reaches the second fixing unit; Equipped with The first determination unit a first arrival time, which is a time it takes for the paper to reach the first fixing unit from the reference position, based on paper information, which is information about the paper, and the first paper transport distance; and determining the first standby temperature to be lower than a first fixable temperature at which the first toner image can be fixed onto the paper, and such that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; The second determination unit A second arrival time, which is a time required for the paper to reach the second fixing unit from the reference position, is calculated based on the paper information and the second paper transport distance, and based on the second arrival time and the paper information,The second standby temperature is determined so that it is lower than a second fixable temperature at which the second toner image can be fixed to the paper, and so that the temperature of the second fixing section will be the second fixable temperature when the paper reaches the second fixing section. In addition, the image forming system of the invention described in claim 2 is a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; An image forming system comprising: a first determination unit that determines a first standby temperature, which is the temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; the first determination unit determines the first standby temperature to be lower than a first fixable temperature at which the first toner image can be fixed to the paper, and such that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; the second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed to the paper and the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit; a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; The timing at which the first control unit increases the temperature of the first fixing unit and the timing at which the second control unit increases the temperature of the second fixing unit are the same.

[0008] Also, claims 3 The invention described in claim 2 In the image forming system described in The second standby temperature is lower than the first standby temperature.

[0009] Also, claims 4 The invention described in claim 2 or 3 In the image forming system described in The first fixable temperature and the second fixable temperature are the same temperature.

[0010] Also, claims 5 The invention described in claim 2 or 3 In the image forming system described in The first fixable temperature is lower than the second fixable temperature.

[0011] Also, claims 6 The invention described in claim 2 or 3 In the image forming system described in The first fixable temperature is higher than the second fixable temperature.

[0012] Also, claims 7 The invention described in claim 2 from 6 In the image forming system according to any one of the above items, the first determination unit determines the first standby temperature based on paper information that is information about the paper; The second determination unit determines the second standby temperature based on the paper information.

[0013] Also, claims 8 The invention described in claim 7 In the image forming system described in The printing apparatus further includes a paper information acquisition unit that acquires the paper information from information on paper on which an image has been formed in the past.

[0014] Also, claims 9 The invention described in claim 2 from 8 In the image forming system according to any one of the above items, a first acquisition unit that acquires a first paper conveyance distance, which is a distance from a reference position to when the paper reaches the first fixing unit; a second acquisition unit that acquires a second paper conveyance distance, which is a distance from the reference position to when the paper reaches the second fixing unit; the first determination unit determines the first standby temperature based on the first paper conveyance distance; The second determination unit determines the second standby temperature based on the second paper transport distance.

[0016] The control device of the invention described in claim 10 comprises: a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; A control device provided in an image forming system including: a first determination unit that determines a first standby temperature, which is the temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; the first determination unit determines the first standby temperature so that the first standby temperature is lower than a first fixable temperature at which the first toner image can be fixed to the paper and so that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; The second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed to the paper and so that the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit. death, a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; The timing at which the first control unit increases the temperature of the first fixing unit and the timing at which the second control unit increases the temperature of the second fixing unit are the same. do.

[0017] The program of the invention described in claim 11 is: a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; A computer of a control device provided in an image forming system including the a first determination unit that determines a first standby temperature, which is the temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; It functions as the first determination unit determines the first standby temperature so that the first standby temperature is lower than a first fixable temperature at which the first toner image can be fixed to the paper and so that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; The second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed to the paper and so that the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit. death, The computer a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; The timing at which the first control unit increases the temperature of the first fixing unit and the timing at which the second control unit increases the temperature of the second fixing unit are the same. do. [Effects of the Invention]

[0018] According to the present invention, it is possible to reduce power consumption while ensuring productivity and fixability. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing the overall configuration of an image forming system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a control block diagram of the image forming system according to the present embodiment. [Figure 3] FIG. 10 is a diagram showing the change over time of the fixing temperature in a conventional example. [Figure 4] 10 is a flowchart showing the flow of a standby temperature determination process. [Figure 5] FIG. 10 is a diagram showing an example of a first table. [Figure 6] FIG. 10 is a diagram illustrating an example of a third table. [Figure 7] FIG. 10 is a diagram showing an example of a fourth table. [Figure 8] FIG. 4 is a diagram showing a change in fixing temperature over time in the present embodiment. [Figure 9] FIG. 4 is a diagram showing a change in fixing temperature over time in the present embodiment. [Figure 10] FIG. 4 is a diagram showing a change in fixing temperature over time in the present embodiment. [Figure 11] FIG. 10 is a diagram showing the overall configuration of a modified image forming system. [Figure 12]FIG. 10 is a diagram showing a change in fixing temperature over time in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present embodiment will be described in detail below with reference to the drawings. An image forming system 10 shown in Fig. 1 includes a first image forming apparatus 100, an intermediate conveying apparatus 300, a second image forming apparatus 200, and a discharge conveying apparatus 400, which are connected in this order.

[0021] It should be noted that a paper feed tray unit (not shown) may be provided upstream of the first image forming apparatus 100, and a post-processing device (not shown) may be provided downstream of the second image forming apparatus 200. The intermediate conveying device 300 includes an inverting section 310 and a cooling section 320. The arrow above the sheet S in the figure indicates the conveying direction of the sheet S. A system configured by connecting two or more image forming apparatuses in series, such as the image forming system 10 shown in FIG. 1, is generally called a serial tandem type image forming system.

[0022] When performing double-sided printing, image forming system 10 feeds paper S from a paper feed tray unit and forms a first toner image on a first side (front side) of paper S using first image forming device 100 (previous stage machine). Then, image forming system 10 inverts paper S using inverting section 310 of intermediate conveying device 300 and conveys paper S to second image forming device 200 (next stage machine). Then, image forming system 10 forms a second toner image on a second side (back side) of paper S using second image forming device 200. After forming the second toner image on the second side of paper S, image forming system 10 discharges paper S using discharge conveying device 400. In this embodiment, the first image forming apparatus 100 and the second image forming apparatus 200 are described as image forming apparatuses that form monochrome images, but are not limited to this and may also be image forming apparatuses that form color images using four colors: C (cyan), M (magenta), Y (yellow), and K (black).

[0023] Next, a description will be given of the functional configuration of the image forming system 10. A block diagram showing the functional configuration of the image forming system 10 is shown in FIG.

[0024] The first image forming device 100 includes a control unit 101, a document reading unit 110, an operation display unit 120, an image processing unit 130, a first image forming unit 140, a conveying unit 150, a first fixing unit 160, a communication unit 171, a memory unit 172, and a first temperature detection unit 180.

[0025] The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, and the like. The CPU 102 reads out a program corresponding to the processing content from the ROM 103, loads it into the RAM 104, and centrally controls the operations of each block of the first image forming apparatus 100 in cooperation with the loaded program.

[0026] The control unit 101 transmits and receives various data to and from the second image forming apparatus 200 via the communication unit 171. The control unit 101 also cooperates with the control unit 201 of the second image forming apparatus 200 via the communication unit 171, and controls the image forming operation by the second image forming apparatus 200 and the cooling operation by the cooling unit 320 of the intermediate conveying device 300.

[0027] Furthermore, the control unit 101 determines a first standby temperature, which is the temperature of the first fixing unit 160 in a standby state where the operation of the first fixing unit 160 is stopped, that is lower than the first fixable temperature so that the temperature of the first fixing unit 160 becomes a first fixable temperature at which a first toner image (described later) can be fixed to the paper S at the timing when the paper S reaches the first fixing unit 160. Here, the control unit 101 functions as a first determination unit. Furthermore, the control unit 101 acquires paper information, which is information relating to the paper S, from information on the paper S on which an image has been formed in the past. Here, the control unit 101 functions as a paper information acquisition unit. Furthermore, the control unit 101 acquires a first paper transport distance, which is the distance from the reference position until the paper S reaches the first fixing unit 160, from the storage unit 172. Here, the control unit 101 functions as a first acquisition unit. Furthermore, the control unit 101 increases the temperature of the first fixing unit 160 so that the temperature of the first fixing unit 160 reaches the first fixable temperature at the timing when the paper S reaches the first fixing unit 160. Here, the control unit 101 functions as a first control unit.

[0028] The document reading unit 110 optically scans the document transported onto the contact glass, and forms an image of the light reflected from the document on the light receiving surface of a CCD (Charge Coupled Device) sensor to read the document. Note that the document is transported onto the contact glass by an automatic document feeder (ADF), but the document may also be placed on the contact glass manually.

[0029] The operation display unit 120 is configured to include a display unit 120a such as an LCD (Liquid Crystal Display), a touch panel 120b provided to cover the display unit 120a, and a group of operation keys (not shown), and receives instructions from a user and outputs the operation signals to the control unit 101. Furthermore, the operation display unit 120 displays various setting screens for inputting various operation instructions and setting information, various processing results, and the like, in accordance with display signals input from the control unit 101.

[0030] The image processing unit 130 includes a circuit for performing analog-to-digital (A / D) conversion processing and a circuit for performing digital image processing. The image processing unit 130 generates digital image data by A / D conversion processing from the analog image signal acquired by the CCD sensor of the document reading unit 110, and outputs the digital image data to the first image forming unit 140 and the second image forming unit 210 (described later).

[0031] First image forming unit 140 forms a first toner image on a first surface of paper S. Specifically, first image forming unit 140 has a photosensitive drum 141, a charging unit 142, an exposure unit (laser light source, polygon mirror) (not shown), a developing unit 143, a transfer unit 144, a separation and neutralization unit (not shown), and a cleaner 145. When forming an image, first image forming unit 140 exposes the surface of photosensitive drum 141, which is uniformly charged by charging unit 142 and rotating, using a laser light source and a polygon mirror, to form an electrostatic latent image corresponding to image data on the surface of photosensitive drum 141. Then, first image forming unit 140 reverse-develops the electrostatic latent image using developing unit 143 to form a first toner image on photosensitive drum 141. Then, first image forming unit 140 sends the fed paper S to a transfer area in accordance with the timing of forming the first toner image. Then, in the transfer area, first image forming unit 140 transfers the first toner image formed on the surface of photosensitive drum 141 onto paper S that has been charged to the opposite polarity by transfer unit 144. Then, first image forming unit 140 separates paper S carrying the first toner image from the surface of photosensitive drum 141 by the action of the separation and discharge unit, sends it to first fixing unit 160, and removes the toner remaining on photosensitive drum 141 by cleaner 145.

[0032] In a configuration in which the first image forming unit 140 forms a color image, the above-mentioned units are provided for each of the colors CMYK, and a toner image for each of the colors CMYK is formed on a photosensitive drum 141 as an image carrier and transferred to the paper S.

[0033] The first fixing section 160 includes a fixing roller 161 arranged on the fixing surface of the paper S, i.e., the side on which the first toner image is formed, a pressure roller 162 arranged on the opposite side of the fixing surface, a heating source 163, etc.

[0034] The amount of heat generated by the heat source 163 is controlled under the control of the control unit 101. This controls the temperature of the first fixing unit 160. Heat source 163 is an internal heat source disposed inside fixing roller 161, and heats first fixing unit 160 from inside first fixing unit 160.

[0035] The first fixing unit 160 applies heat and pressure to the first toner image on the paper S introduced into the fixing nip (thermal fixing), thereby fixing the first toner image to the paper S. As a result, a fixed toner image is formed on the first surface of the paper S.

[0036] The communication unit 171 connects to an external device (for example, a personal computer) via a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network), and transmits and receives various data to and from the external device. The control unit 101 receives, for example, image data transmitted from the external device, and forms an image on paper S based on this image data. The communication unit 171 is configured by a communication control card such as a LAN card.

[0037] The storage unit 172 is configured by, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive. The storage unit 172 stores various programs executed by the control unit 101 as well as parameters, data, etc. required by each unit. Furthermore, storage unit 172 stores a first paper transport distance, which will be described later. The storage unit 172 also stores a first table, a second table, and a third table, which will be described later. The storage unit 172 also stores information such as the paper type and basis weight of the paper S on which an image was formed in a past image forming (printing) process, and information such as the paper type and basis weight of the paper S that was initially set.

[0038] The first temperature detection unit 180 is, for example, a thermistor or a thermocouple, and detects the temperature of the first fixing unit 160. The control unit 101 controls the temperature of the first fixing unit 160 based on the detection result detected by the first temperature detection unit 180.

[0039] The second image forming apparatus 200 includes a control unit 201, a second image forming unit 210, a conveying unit 220, a second fixing unit 230, a communication unit 241, a storage unit 242, a second temperature detection unit 250, and the like.

[0040] The processing of each part of the control unit 201, conveying unit 220, second fixing unit 230, communication unit 241 and memory unit 242 in the second image forming apparatus 200 is similar to the processing of the control unit 101, conveying unit 150, first fixing unit 160, communication unit 171 and memory unit 172 described in the first image forming apparatus 100, so description thereof will be omitted here.

[0041] Furthermore, the control unit 201 determines a second standby temperature, which is the temperature of the second fixing unit 230 in a standby state where the operation of the second fixing unit 230 is stopped, that is lower than the second fixable temperature so that the temperature of the second fixing unit 230 becomes a second fixable temperature at which the second toner image can be fixed to the paper S at the timing when the paper S reaches the second fixing unit 230. Here, the control unit 201 functions as a second determination unit. Furthermore, the control unit 201 acquires paper information, which is information relating to the paper S, from information on the paper S on which an image has been formed in the past. Here, the control unit 201 functions as a paper information acquisition unit. Furthermore, the control unit 201 acquires, from the storage unit 242, a second paper transport distance, which is the distance from the reference position until the paper S reaches the second fixing unit 230. Here, the control unit 201 functions as a second acquisition unit. Furthermore, the control unit 201 increases the temperature of the second fixing unit 230 so that the temperature of the second fixing unit 230 reaches the second fixable temperature at the timing when the paper S reaches the second fixing unit 230. Here, the control unit 201 functions as a second control unit.

[0042] The second image forming unit 210 forms a second toner image on the second surface (the surface opposite to the first surface) of the paper S. The specific processing is the same as that of the first image forming unit 140, and therefore a description thereof will be omitted here.

[0043] The storage unit 242 also stores a second paper transport distance, which will be described later. The storage unit 242 also stores a first table, a second table, and a fourth table, which will be described later. In addition, like memory unit 172, memory unit 242 stores information such as the paper type and basis weight of paper S on which an image was formed in a past image forming (printing) process, as well as information such as the paper type and basis weight of paper S that was initially set.

[0044] Second fixing unit 230 includes fixing roller 231, pressure roller 232, and heat source 233. Fixing roller 231, pressure roller 232, and heat source 233 have the same configurations as fixing roller 161, pressure roller 162, and heat source 163 in first fixing unit 160.

[0045] The second temperature detection unit 250 has the same configuration as the first temperature detection unit 180, and detects the temperature of the second fixing unit 230. The control unit 201 controls the temperature of the second fixing unit 230 based on the detection result detected by the second temperature detection unit 250.

[0046] Intermediate conveying device 300 is a part that conveys paper S conveyed from first image forming device 100 to second image forming device 200, and is equipped with cooling section 320 and the like. Cooling section 320 is, for example, a fan, and cools paper S conveyed from first image forming device 100 in accordance with the control of control section 101. In second image forming device 200, second image forming section 210 is likely to rise in temperature due to paper S on which an image has been formed in first image forming device 100, so cooling paper S by cooling section 320 prevents second image forming section 210 from rising in temperature too much.

[0047] The paper discharge transport device 400 is a part that discharges the paper S transported from the second image forming device 200, and is provided with a paper discharge tray 410 for stacking the discharged paper S, etc.

[0048] Next, temperature control of first fixing section 160 and second fixing section 230 in this embodiment will be described.

[0049] 3 shows the temperature changes over time in the first fixing section 160 (solid line) and the second fixing section 230 (dotted line) of the conventional example. In the example shown in Fig. 3, the horizontal axis represents time and the vertical axis represents the temperature of the fixing section. Also, time t0 is the timing when the state switches from the preparation state before printing starts to the printing start state, time t1 is the timing when the paper S reaches the first fixing section 160, and time t2 is the timing when the paper S reaches the second fixing section 230. Further, the temperature T is a fixable temperature (for example, 210° C.) at which the toner image can be fixed to the paper S. In the example shown in FIG. 3, the fixable temperature (first fixable temperature) in the first fixing unit 160 and the fixable temperature (second fixable temperature) in the second fixing unit 230 are the same, that is, the temperature T. 3, in the conventional example, control unit 101 controlled first fixing unit 160 so that the standby temperature (first standby temperature), which is the temperature of first fixing unit 160 in the period before time t1, became temperature T. Control unit 201 also controlled second fixing unit 230 so that the standby temperature (second standby temperature), which is the temperature of second fixing unit 230 in the period before time t2, became temperature T.

[0050] In this embodiment, the control unit 101 determines a first standby temperature that is lower than the first fixable temperature so that the temperature of the first fixing unit 160 becomes the first fixable temperature at time t1 based on the first arrival time from time t0 to time t1 and the first fixable temperature. In addition, based on the second arrival time from time t0 to time t2 and the second fixable temperature, the control unit 201 determines a second standby temperature that is lower than the second fixable temperature so that the temperature of the second fixing unit 230 becomes the second fixable temperature at time t2. By controlling the first standby temperature to be lower than the first fixable temperature and the second standby temperature to be lower than the second fixable temperature, power consumption can be reduced while ensuring fixability in the first fixing section 160 and the second fixing section 230.

[0051] 4 shows a flowchart of a standby temperature determination process for determining the first standby temperature and the second standby temperature. The standby temperature determination process is executed by the control units 101 and 201 in the image forming system 10.

[0052] In the standby temperature determination process, first, the control unit 101 acquires from the storage unit 172 a first paper transport distance, which is the distance from a reference position to the first fixing unit 160 in the image forming system 10 (step S1). The first paper transport distance is set in advance based on the configuration of the image forming system 10. The reference position is, for example, a position where the paper S is fed from a paper feed tray unit provided upstream of the first image forming apparatus 100. Next, the control unit 101 acquires information such as the paper type and basis weight of the paper S (step S2). The information such as the paper type and basis weight of the paper S may be acquired from the storage unit 172 as information on the paper type and basis weight of the paper S on which an image was formed in the previous image formation (printing) process, or may be acquired from the storage unit 172 as information on the paper type and basis weight of the paper S most used in the image formation processes of the most recent 10 jobs. Note that the number of most recent jobs is not limited to 10 and can be set arbitrarily. Alternatively, information such as the paper type and basis weight of the paper S initially set in advance may be acquired from the storage unit 172.

[0053] Next, the control unit 101 acquires a first paper transport speed, which is the speed at which the paper S is transported to the first fixing unit 160, based on the paper type, basis weight, etc. of the paper S acquired in step S2 (step S3). The first paper transport speed is set in advance in a first table based on the paper type, basis weight, etc. of the paper S, and is stored in the storage unit 172. An example of the first table is shown in Figure 5. The heavier the paper is in terms of basis weight and the rougher the surface of the paper, the more difficult it is for the toner image to be fixed to the paper. Therefore, as shown in Figure 5, the paper transport speed is reduced to ensure fixation. Next, the control unit 101 calculates a first arrival time based on the first paper transport distance acquired in step S1 and the first paper transport speed acquired in step S3 (step S4).

[0054] Next, the control unit 101 determines the first fixable temperature based on the paper type, basis weight, etc. of the paper S acquired in step S2 (step S5). The first fixable temperature is preset in a second table (not shown) based on the paper type, basis weight, etc. of the paper S, and is stored in the storage unit 172. The heavier the basis weight of the paper, and the rougher the surface of the paper, the more difficult it is for the toner image to be fixed to the paper, so the temperature of the fixing unit is raised to ensure fixability. In addition, if the paper S has a large basis weight and a rough surface, fixability can be ensured by slowing down the paper transport speed and increasing the temperature of the fixing unit, or fixability can be ensured by simply increasing the temperature of the fixing unit without slowing down the paper transport speed, or fixability can be ensured by simply slowing down the paper transport speed without increasing the temperature of the fixing unit.

[0055] Next, based on the first arrival time calculated in step S4 and the first fixable temperature determined in step S5, control unit 101 determines a first standby temperature that is lower than the first fixable temperature so that the temperature of first fixing unit 160 becomes the first fixable temperature at time t1 (step S6). The first standby temperature may be obtained from a third table (FIG. 6) that is preset based on the first arrival time and the first fixable temperature, or may be calculated based on the first arrival time and the first fixable temperature.

[0056] Fig. 6 shows an example of the third table when the first fixable temperature is 210°C. As shown in Fig. 6, the slower the first paper transport speed is and the longer the first arrival time is, the lower the first standby temperature can be set. In other words, power consumption can be reduced.

[0057] Next, the control unit 201 acquires from the storage unit 242 a second paper transport distance, which is the distance from the reference position to the second fixing unit 230 in the image forming system 10. The second paper transport distance is set in advance based on the configuration of the image forming system 10. The reference position is, for example, a position where the paper S is fed from a paper feed tray unit provided upstream of the first image forming apparatus 100. Next, the control unit 201 acquires information such as the paper type and basis weight of the paper S (step S8). The information such as the paper type and basis weight of the paper S may be acquired from the storage unit 242 as information on the paper type and basis weight of the paper S on which an image was formed in the previous image formation (printing) process, or may be acquired from the storage unit 242 as information on the paper type and basis weight of the paper S most used in the image formation processes of the most recent 10 jobs. Note that the number of most recent jobs is not limited to 10 and can be set arbitrarily. Alternatively, information such as the paper type and basis weight of the paper S initially set in advance may be acquired from the storage unit 242. Furthermore, the information on the paper type, basis weight, etc. of the sheet S that the control unit 101 acquired in step S2 may be acquired from the first image forming apparatus 100.

[0058] Next, the control unit 201 acquires a second paper transport speed, which is the speed at which the paper S is transported to the second fixing unit 230, based on the paper type, basis weight, etc. of the paper S acquired in step S8 (step S9). The second paper transport speed, like the first paper transport speed, is set in advance in the first table based on the paper type, basis weight, etc. of the paper S. Note that the first sheet transport speed acquired by control unit 101 in step S3 may be acquired from first image forming apparatus 100 as the second sheet transport speed. Next, the control unit 201 calculates the second arrival time based on the second paper transport distance acquired in step S7 and the second paper transport speed acquired in step S9 (step S10).

[0059] Next, the control unit 201 determines the second fixable temperature based on the paper type, basis weight, etc. of the paper S acquired in step S8 (step S11). The second fixable temperature is set in advance in the second table based on the paper type, basis weight, etc. of the paper S, just like the first fixable temperature. The control unit 201 may determine the second fixable temperature based on the type and basis weight of the paper S and the effect of forming an image on the paper S by the first image forming apparatus 100.

[0060] Next, based on the second arrival time calculated in step S10 and the second fixable temperature determined in step S11, control unit 201 determines a second standby temperature that is lower than the second fixable temperature so that the temperature of second fixing unit 230 becomes the second fixable temperature at time t2 (step S12), and then ends the process. The second standby temperature may be obtained from a fourth table (FIG. 7) that is preset based on the second arrival time and the second fixable temperature, or may be calculated based on the second arrival time and the second fixable temperature. The control unit 201 may acquire the first standby temperature from the first image forming apparatus 100, and determine the second standby temperature based on the second reaching time, the second fixable temperature, and the first standby temperature.

[0061] Fig. 7 shows an example of the fourth table when the second fixable temperature is 210°C. As shown in Fig. 7, the slower the second paper transport speed is and the longer the second arrival time is, the lower the second standby temperature can be set. In other words, power consumption can be reduced. Furthermore, as shown in Figures 6 and 7, when the first fixable temperature and the second fixable temperature are the same, the standby temperature (second standby temperature) in the second fixing section 230, which takes longer for the paper S to reach, can be set lower than the first standby temperature.

[0062] 8 shows the temperature changes over time in the first fixing unit 160 (solid line) and the second fixing unit 230 (dotted line) of this embodiment. In the example shown in Fig. 8, the first fixable temperature and the second fixable temperature are the same, temperature T (e.g., 210°C). 8, during a period before time t1, control unit 101 controls first fixing unit 160 so that the temperature of first fixing unit 160 becomes a first standby temperature that is lower than temperature T. Then, control unit 101 controls first fixing unit 160 to start raising the temperature of first fixing unit 160 at time t0 so that the temperature becomes temperature T at time t1. Furthermore, in a period before time t2, control unit 201 controls second fixing unit 230 so that the temperature of second fixing unit 230 becomes a second standby temperature that is lower than temperature T. Then, control unit 201 controls second fixing unit 230 to start raising the temperature of second fixing unit 230 at time t0 so that the temperature becomes temperature T at time t2. By controlling the first fixing section 160 and the second fixing section 230 to start heating at time t0, the first standby temperature and the second standby temperature can be set lower, thereby further reducing power consumption while ensuring productivity and fixability. Furthermore, as shown in FIG. 8, when the first fixable temperature and the second fixable temperature are the same as described above, the standby temperature (second standby temperature) in the second fixing section 230, which takes the paper S longer to reach, can be set lower than the first standby temperature.

[0063] FIG. 9 also shows the change in temperature over time in the first fixing section 160 (solid line) and the second fixing section 230 (dotted line) when the first fixable temperature (temperature T1) is lower than the second fixable temperature (temperature T2). In the case shown in FIG. 9, by executing the standby temperature determination process, the control unit 101 can determine the first standby temperature, and the control unit 201 can determine the second standby temperature. Then, control unit 101 controls first fixing unit 160 so that the temperature of first fixing unit 160 becomes a first standby temperature that is lower than temperature T1 during a period before time t1. Then, control unit 101 controls first fixing unit 160 to start raising the temperature of first fixing unit 160 at time t0 so that the temperature becomes temperature T1 at time t1. Furthermore, in a period before time t2, control unit 201 controls second fixing unit 230 so that the temperature of second fixing unit 230 becomes a second standby temperature that is lower than temperature T2. Then, control unit 201 controls second fixing unit 230 to start raising the temperature of second fixing unit 230 at time t0 so that the temperature becomes temperature T2 at time t2. In the example shown in FIG. 9, the second standby temperature is higher than the first standby temperature.

[0064] FIG. 10 also shows the change in temperature over time in the first fixing section 160 (solid line) and the second fixing section 230 (dotted line) when the first fixable temperature (temperature T1) is higher than the second fixable temperature (temperature T2). In the case shown in FIG. 10, by executing the standby temperature determination process, the control unit 101 can determine the first standby temperature, and the control unit 201 can determine the second standby temperature. Then, control unit 101 controls first fixing unit 160 so that the temperature of first fixing unit 160 becomes a first standby temperature that is lower than temperature T1 during a period before time t1. Then, control unit 101 controls first fixing unit 160 to start raising the temperature of first fixing unit 160 at time t0 so that the temperature becomes temperature T1 at time t1. Furthermore, in a period before time t2, control unit 201 controls second fixing unit 230 so that the temperature of second fixing unit 230 becomes a second standby temperature that is lower than temperature T2. Then, control unit 201 controls second fixing unit 230 to start raising the temperature of second fixing unit 230 at time t0 so that the temperature becomes temperature T2 at time t2. In the example shown in FIG. 10, similarly to the case of FIG. 8, the second standby temperature can be set lower than the first standby temperature.

[0065] (Variation) Next, a modification of the above embodiment will be described. The following description will focus on the differences from the above embodiment. The configuration of the image forming system 10 of this modification includes an intermediate conveying device 500 between the intermediate conveying device 300 and the second image forming device 200 of the image forming system 10 of the above embodiment. FIG. 11 shows the overall configuration of an image forming system 10 according to this modified example.

[0066] The intermediate conveying device 500 is a part that conveys the paper S conveyed from the intermediate conveying device 300 to the second image forming device 200. Further, instead of the intermediate conveyance device 500, a curl adjusting device that corrects curls and / or ripples of the sheet S, a humidifying device that humidifies the sheet S, or a sheet inserting device that inserts the sheet S may be used.

[0067] In the configuration of the image forming system 10 of this modified example, the second paper conveying distance is longer by the length of the intermediate conveying device 500 than in the configuration of the image forming system 10 of the above embodiment. The information on the second paper conveying distance may be input by the user via the operation display unit 120, or the control unit 201 may detect that the intermediate conveying device 500 has been installed in the image forming system 10 and obtain information on the second paper conveying distance of the image forming system 10 including the intermediate conveying device 500 that has been pre-stored in the memory unit 242.

[0068] In this modified example, compared to the above embodiment, the second paper transport distance is longer by the length of the intermediate transport device 500, so if the second paper transport speed in this modified example is the same as in the above embodiment, the second arrival time in this modified example is longer than the second arrival time in the above embodiment. Figure 12 shows the temperature changes over time in the first fixing section 160 (solid line) and the second fixing section 230 (dotted line) when the first fixable temperature and the second fixable temperature are the same temperature T and the second arrival time is longer than in the case shown in Figure 8. In the case shown in FIG. 12, by executing the standby temperature determination process, the control unit 101 can determine the first standby temperature, and the control unit 201 can determine the second standby temperature. Then, in a period before time t1, control unit 101 controls first fixing unit 160 so that the temperature of first fixing unit 160 becomes a first standby temperature that is lower than temperature T. Then, control unit 101 controls first fixing unit 160 to start raising the temperature of first fixing unit 160 at time t0 so that the temperature becomes temperature T at time t1. Furthermore, in a period before time t2, control unit 201 controls second fixing unit 230 so that the temperature of second fixing unit 230 becomes a second standby temperature that is lower than temperature T. Then, control unit 201 controls second fixing unit 230 to start raising the temperature of second fixing unit 230 at time t0 so that the temperature becomes temperature T at time t2. Furthermore, as shown in FIGS. 8 and 12, the longer the second reaching time, the lower the second standby temperature can be set.

[0069] In the above embodiment, the image forming system 10 is configured to connect two image forming apparatuses, the first image forming apparatus 100 and the second image forming apparatus 200, but the present invention is not limited to this. For example, the image forming system may be configured so that a single image forming apparatus includes a first fixing unit and a second fixing unit. In this case, an integrated control unit (control device) provided in the image forming apparatus functions as the control unit 101 and the control unit 201, and determines both the first standby temperature and the second standby temperature. In the above embodiment, the control unit 101 may determine both the first standby temperature and the second standby temperature. In this case, the control unit 101 functions as a control device. In the above embodiment, the control unit 201 may determine both the first standby temperature and the second standby temperature. In this case, the control unit 201 functions as a control device.

[0070] As described above, the image forming system 10 of this embodiment is an image forming system 10 including a first fixing unit 160 that fixes a first toner image formed on a sheet S, and a second fixing unit 230 that fixes a second toner image formed on the sheet S after the first toner image has been fixed on the sheet S by the first fixing unit 160, and further including a first determination unit (control unit 101) that determines a first standby temperature, which is the temperature of the first fixing unit 160 in a standby state, and a second determination unit (control unit 201) that determines a second standby temperature, which is the temperature of the second fixing unit 230 in a standby state, The first determination unit determines a first standby temperature that is lower than a first fixable temperature at which a first toner image can be fixed to the paper S and that will cause the temperature of the first fixing unit 160 to be the first fixable temperature when the paper S reaches the first fixing unit 160 (time t1), and the second determination unit determines a second standby temperature that is lower than a second fixable temperature at which a second toner image can be fixed to the paper S and that will cause the temperature of the second fixing unit 230 to be the second fixable temperature when the paper S reaches the second fixing unit 230 (time t2). Therefore, in the standby state, the temperature of first fixing unit 160 is set lower than the first fixable temperature, and the temperature of second fixing unit 230 is set lower than the second fixable temperature, thereby reducing power consumption. Furthermore, the temperature of first fixing unit 160 is controlled to be the first fixable temperature at time t1, and the temperature of second fixing unit 230 is controlled to be the second fixable temperature at time t2, thereby ensuring productivity and fixability.

[0071] In the image forming system 10 of the present embodiment, the second standby temperature is lower than the first standby temperature. Therefore, in an image forming system in which the second paper transport distance is longer than the first paper transport distance, the second standby temperature can be set lower than the first standby temperature, thereby reducing power consumption.

[0072] In the image forming system 10 of the present embodiment, the first fixable temperature and the second fixable temperature are the same temperature. Therefore, even when the first fixable temperature and the second fixable temperature are the same temperature, it is possible to reduce power consumption while ensuring productivity and fixability.

[0073] In the image forming system 10 of the present embodiment, the first fixable temperature is lower than the second fixable temperature. Therefore, even when the first fixable temperature is lower than the second fixable temperature, it is possible to reduce power consumption while ensuring productivity and fixability.

[0074] In the image forming system 10 of the present embodiment, the first fixable temperature is higher than the second fixable temperature. Therefore, even when the first fixable temperature is higher than the second fixable temperature, it is possible to reduce power consumption while ensuring productivity and fixability.

[0075] Furthermore, in the image forming system 10 of this embodiment, the first determination unit determines the first standby temperature based on paper information, which is information about the paper S, and the second determination unit determines the second standby temperature based on the paper information. Therefore, the first standby temperature and the second standby temperature can be determined based on the paper information of the paper S, and power consumption can be reduced while ensuring productivity and fixability.

[0076] Furthermore, the image forming system 10 of this embodiment includes a paper information acquisition unit (control unit 101, control unit 201) that acquires paper information from information on paper S on which an image has been formed in the past. Therefore, the paper information of the paper S can be easily acquired.

[0077] In addition, the image forming system 10 of this embodiment is equipped with a first acquisition unit (control unit 101) that acquires a first paper transport distance, which is the distance from the reference position until the paper S reaches the first fixing unit 160, and a second acquisition unit (control unit 201) that acquires a second paper transport distance, which is the distance from the reference position until the paper S reaches the second fixing unit 230, and the first determination unit determines a first standby temperature based on the first paper transport distance, and the second determination unit determines a second standby temperature based on the second paper transport distance. Therefore, the first standby temperature and the second standby temperature can be determined based on information on the first paper transport distance and the second paper transport distance, thereby reducing power consumption while ensuring productivity and fixability.

[0078] Furthermore, the image forming system 10 of this embodiment includes a first control unit (control unit 101) that raises the temperature of the first fixing unit 160 so that the temperature of the first fixing unit 160 reaches the first fixable temperature when the paper S arrives at the first fixing unit 160, and a second control unit (control unit 201) that raises the temperature of the second fixing unit 230 so that the temperature of the second fixing unit 230 reaches the second fixable temperature when the paper S arrives at the second fixing unit 230, and the timing at which the first control unit raises the temperature of the first fixing unit 160 and the timing at which the second control unit raises the temperature of the second fixing unit 230 are the same. Therefore, by starting to raise the temperature of the first fixing section 160 and the second fixing section 230 at time t0, the first standby temperature and the second standby temperature can be set lower, thereby further reducing power consumption while ensuring productivity and fixability.

[0079] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present invention. For example, in step S5 of the standby temperature determination process executed in image forming system 10 according to the above embodiment, control unit 101 determines the first fixable temperature based on the paper type and basis weight. Also, in step S11, control unit 201 determines the second fixable temperature based on the paper type and basis weight, but this is not limiting. First image forming apparatus 100 may include a detector that detects the temperature and humidity around first fixing unit 160, and control unit 101 may determine the first fixable temperature based on environmental information (e.g., temperature, humidity, etc.) detected by the detector. Second image forming apparatus 200 may include a detector that detects the temperature and humidity around second fixing unit 230, and control unit 201 may determine the second fixable temperature based on environmental information (e.g., temperature, humidity, etc.) detected by the detector.

[0080] Furthermore, in the image forming system 10 according to the above embodiment, the discharged paper conveying device 400 may include a second cooling unit. The second cooling unit is, for example, a fan, and cools the paper S conveyed from the second image forming device 200 under the control of the control unit 101. In the image forming system 10, double-sided printing is performed, so when the paper S is discharged and stacked in the paper discharge unit, the image-formed sides face each other. Therefore, if the temperature of the paper S is high, the toner on the facing sides when stacked in the paper discharge unit is likely to melt and stick to each other, causing tacking. However, by cooling the paper S using the second cooling unit, the occurrence of tacking can be suppressed.

[0081] The image forming system 10 according to the above embodiment may be an image forming system that forms a color image, an image forming system that forms a single-color image (e.g., a monochrome image), or an image forming system in which an image forming apparatus that forms a color image and an image forming apparatus that forms a single-color image are connected.

[0082] Furthermore, the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from the gist or main features thereof. [Explanation of symbols]

[0083] 10. Image forming system 100 1st image forming device 101 control unit (first determination unit, paper information acquisition unit, first acquisition unit, first control unit) 102 CPU 103 ROM 104 RAM 110 Document reading unit 120 Operation display section 130 Image processing section 140 First image forming unit 141 Photosensitive drum 142 Charging section 143 Development Unit 144 Transcription Unit 145 Cleaner 160 First fixing part 161 Fixing roller 162 Pressure roller 163 Heating source 171 Communications Department 172 Memory section 180 First temperature detection unit 200 Second image forming device 201 control unit (second determination unit, paper information acquisition unit, second acquisition unit, second control unit) 202 CPU 203 ROM 204 RAM 210 Second image forming unit 211 Photosensitive drum 212 Charging section 213 Development Unit 214 Transcription Unit 215 Cleaner 230 Second Fixing Section 231 Fixing roller 232 Pressure roller 233 Heating source 241 Communications Department 242 Storage section 250 Second temperature detection unit 300 Intermediate conveying device 310 Inversion section 320 Cooling section 400 Paper delivery transport device 410 Paper output tray

Claims

1. a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; An image forming system comprising: a first determination unit that determines a first standby temperature, which is a temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; a first acquisition unit that acquires a first paper transport distance, which is a distance from a reference position to when the paper reaches the first fixing unit; a second acquisition unit that acquires a second paper conveyance distance, which is a distance from the reference position to when the paper reaches the second fixing unit; the first determination unit calculates a first arrival time, which is a time required for the paper to reach the first fixing unit from the reference position, based on paper information, which is information related to the paper, and the first paper transport distance; and determines the first standby temperature, based on the first arrival time and the paper information, such that the first standby temperature is lower than a first fixable temperature at which the first toner image can be fixed to the paper, and that the temperature of the first fixing unit becomes the first fixable temperature at the time the paper reaches the first fixing unit; The second determination unit calculates a second arrival time, which is a time required for the paper to reach the second fixing unit from the reference position, based on the paper information and the second paper transport distance, and determines the second standby temperature, based on the second arrival time and the paper information, to be lower than a second fixable temperature at which the second toner image can be fixed onto the paper, and such that the temperature of the second fixing unit becomes the second fixable temperature at the timing when the paper reaches the second fixing unit. Imaging system.

2. A first fixing unit that fixes a first toner image formed on a sheet of paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; An image forming system comprising: a first determination unit that determines a first standby temperature, which is a temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; the first determination unit determines the first standby temperature to be lower than a first fixable temperature at which the first toner image can be fixed onto the paper, and such that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; the second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed to the paper and the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit; a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; The timing at which the first control unit increases the temperature of the first fixing unit is the same as the timing at which the second control unit increases the temperature of the second fixing unit. Imaging system.

3. The image forming system according to claim 2 , wherein the second standby temperature is lower than the first standby temperature.

4. 4. The image forming system according to claim 2, wherein the first fixable temperature and the second fixable temperature are the same temperature.

5. 4. The image forming system according to claim 2, wherein the first fixable temperature is lower than the second fixable temperature.

6. 4. The image forming system according to claim 2, wherein the first fixable temperature is higher than the second fixable temperature.

7. the first determination unit determines the first standby temperature based on paper information that is information about the paper; The image forming system according to claim 2 , wherein the second determination unit determines the second standby temperature based on the paper information.

8. The image forming system according to claim 7 , further comprising a paper information acquisition unit that acquires the paper information from information on paper on which an image has been formed in the past.

9. a first acquisition unit that acquires a first paper transport distance, which is a distance from a reference position to when the paper reaches the first fixing unit; a second acquisition unit that acquires a second paper conveyance distance, which is a distance from the reference position to when the paper reaches the second fixing unit; the first determination unit determines the first standby temperature based on the first paper conveyance distance; The image forming system according to claim 2 , wherein the second determination unit determines the second standby temperature based on the second paper transport distance.

10. a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; A control device provided in an image forming system including: a first determination unit that determines a first standby temperature, which is a temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; the first determination unit determines the first standby temperature so that the first standby temperature is lower than a first fixable temperature at which the first toner image can be fixed onto the paper and so that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; the second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed onto the paper and so that the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit; a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; The control device wherein the first control unit increases the temperature of the first fixing unit at the same time as the second control unit increases the temperature of the second fixing unit.

11. a first fixing unit that fixes the first toner image formed on the paper; a second fixing section that fixes a second toner image formed on the paper after the first toner image has been fixed on the paper in the first fixing section; A computer of a control device provided in an image forming system including the a first determination unit that determines a first standby temperature, which is the temperature of the first fixing unit in a standby state; a second determination unit that determines a second standby temperature, which is the temperature of the second fixing unit in a standby state; It functions as the first determination unit determines the first standby temperature so that the first standby temperature is lower than a first fixable temperature at which the first toner image can be fixed onto the paper and so that the temperature of the first fixing unit becomes the first fixable temperature at a timing when the paper reaches the first fixing unit; the second determination unit determines the second standby temperature so that the second standby temperature is lower than a second fixable temperature at which the second toner image can be fixed onto the paper and so that the temperature of the second fixing unit becomes the second fixable temperature at a timing when the paper reaches the second fixing unit; The computer a first control unit that increases the temperature of the first fixing unit so that the temperature of the first fixing unit reaches the first fixable temperature when the paper reaches the first fixing unit; a second control unit that increases the temperature of the second fixing unit so that the temperature of the second fixing unit reaches the second fixable temperature when the paper reaches the second fixing unit; a program in which the first control unit increases the temperature of the first fixing unit at the same time as the second control unit increases the temperature of the second fixing unit;

Images