Image forming apparatus

Abstract

To further shorten a time required from the start of an apparatus to completion of a print job.SOLUTION: An image forming apparatus includes: a controller control section 100; and an engine control section 200 that controls a printer engine PE to cause an image forming section 12 to form an image on recording paper, and causes a fixing section 13 to fix the image on the recording paper to execute a print job. When the controller control section 100 requests the start of the printer engine PE, the engine control section 200 performs a predetermined initial operation required before the start of execution of the print job and a warm-up operation for raising a temperature of the fixing section 13 to a predetermined target temperature in parallel and starts the execution of the print job for predetermined processing which can be executed even if the warm-up operation is not completed, on the basis of job information, when the initial operation is completed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus including a fixing unit that fixes an image on a recording sheet.

Background Art

[0002] Some image forming apparatuses such as copiers and multifunction peripherals include an image forming unit that forms an image on a recording sheet and a fixing unit that fixes the image formed by the image forming unit on the recording sheet. In such an image forming apparatus, after the startup of the apparatus, a warm-up operation is performed to raise the temperature of the fixing unit to a predetermined target temperature, and after the completion of the warm-up operation, the execution of a print job is started.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above image forming apparatus, since the execution of the print job is not started until the warm-up operation is completed, the time required from the start of startup to the completion of the print job becomes long.

[0005] In the above Patent Documents 1 and 2, techniques for accelerating the start timing of the temperature rise of the fixing unit are described. By accelerating the start timing of the temperature rise of the fixing unit, the timing at which the temperature of the fixing unit reaches the target temperature becomes earlier, and as a result, the start of the execution of the print job can also be accelerated, and the above required time can be shortened. However, since both start printing after the temperature of the fixing device has risen to a printable temperature, there is a limit to accelerating the start timing of the temperature rise.

[0006] This invention has been made in view of the above circumstances, and aims to shorten the time required from the start of the device until the completion of the print job. [Means for solving the problem]

[0007] An image forming position according to one aspect of the present invention comprises: an image forming unit that forms an image on recording paper; a fixing unit that fixes the image formed in the image forming unit to the recording paper; an engine control unit that controls a printer engine comprising the image forming unit and the fixing unit to execute a print job by causing the image forming unit to form an image on the recording paper and the fixing unit to fix the image to the recording paper; and a controller control unit that requests the engine control unit to start the printer engine and transmits job information indicating the content of the print job to the engine control unit. The engine control unit further controls the printer engine when the controller control unit requests the printer engine to start, performing in parallel predetermined initial operations necessary before the start of execution of the print job and a warm-up operation that raises the temperature of the fixing unit to a predetermined target temperature. When the initial operations are completed, the engine control unit starts executing the print job for predetermined processes that can be executed even if the warm-up operation is not completed, based on the job information. [Effects of the Invention]

[0008] According to the present invention, it becomes possible to start executing a print job without waiting for the warm-up operation to complete. That is, it becomes possible to feed recording paper into the image forming unit and start forming an image on the recording paper during the warm-up operation (while the fuser unit is heating up). This makes it possible to effectively utilize the warm-up operation time and shorten the time required from the start of the device to the completion of the print job compared to conventional methods. [Brief explanation of the drawing]

[0009] [Figure 1]This is a schematic partial front view showing the main structural parts of an image forming apparatus according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing the structure of the fixing section in an image forming apparatus. [Figure 3] This is a functional block diagram that schematically shows the main internal components of an image forming apparatus. [Figure 4] This flowchart shows an example of processing performed in the controller control unit and engine control unit of an image forming apparatus. [Figure 5] This figure shows an example of the control flow performed in the engine control unit and the temperature change in the fixing unit. [Figure 6] This figure shows an example of the control flow performed in a conventional engine control unit. [Figure 7] This figure shows an example of the control flow performed in the engine control unit and the temperature change in the fixing unit. [Modes for carrying out the invention]

[0010] Hereinafter, an image forming apparatus according to one embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic partial front view showing the main structural parts of an image forming apparatus according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing the structure of the fixing section in the image forming apparatus.

[0011] The image forming apparatus 1 is a multifunction device that combines multiple functions, such as a copy function, a printer function, a scanner function, and a facsimile function, and is composed of an image forming unit 12, a fixing unit 13, a paper feeding unit 14, and a transport unit 19.

[0012] The image forming unit 12 forms an image on the recording paper P and includes an intermediate transfer unit 120, a photosensitive drum 121 for black, magenta, cyan, and yellow, and a secondary transfer roller 210. The intermediate transfer unit 120 is composed of an intermediate transfer belt 125 on which a toner image is transferred, a drive roller 125A, a driven roller 125B, and a primary transfer roller 126.

[0013] The intermediate transfer belt 125 is stretched between the driving roller 125A and the driven roller 125B, and is driven by the driving roller 125A while being in contact with the circumferential surface of the photosensitive drum 121, and runs endlessly while being synchronized with the photosensitive drum 121.

[0014] The toner images of each color (black, magenta, cyan, yellow) transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 by adjusting the transfer timing to form a color toner image.

[0015] The secondary transfer roller 210 transfers the color toner image formed on the surface of the intermediate transfer belt 125 to the recording paper P from the paper feed unit 14 via the conveyance path 190 at the nip portion N1 between the driving roller 125A with the intermediate transfer belt 125 interposed therebetween.

[0016] The conveyance unit 19 includes a conveyance path 190 connecting the paper feed unit 14 and a discharge tray (discharge unit), not shown in the figure. Along the conveyance path 190, there are a registration roller pair 191 provided upstream of the nip portion N1 (image formation position where an image is formed on the recording paper P in the image forming unit 12) in the recording paper conveyance direction, a registration sensor 192 provided upstream of the registration roller pair 191 in the recording paper conveyance direction, and an intermediate roller pair 193 provided between the registration roller pair 191 and the paper feed unit 14. The conveyance unit 19 conveys the recording paper P from the paper feed unit 14 through the image forming unit 12 and the fixing unit 13 to the discharge tray and discharges the recording paper P to the discharge tray.

[0017] The registration roller pair 191 stops the recording paper P conveyed at the nip portion N2 formed by the registration roller pair 191 and re-conveys the recording paper P to the nip portion N1.

[0018] The registration sensor 192 is provided to adjust the stop timing of the recording paper P. The registration sensor 192 is composed of, for example, a known reflection-type photoelectric sensor including a light-emitting element and a light-receiving element that detects the reflected light from the recording paper P of the light emitted from the light-emitting element, and detects the leading edge or trailing edge of the recording paper P.

[0019] The intermediate roller pair 193 is for conveying the recording paper P toward the registration roller pair 191.

[0020] The paper feed unit 14 includes a plurality of paper feed cassettes 141A to 141C (hereinafter, also simply referred to as "paper feed cassette 141"). Each of the paper feed cassettes 141A to 141C includes a pickup roller 142, a feed roller 143, a retard roller 144 disposed opposite to the feed roller 143, and a conveying roller pair 145.

[0021] The pickup roller 142 is for picking up the recording paper P accommodated in the paper feed cassette 141. The feed roller 143 and the retard roller 144 are for separating the recording paper P picked up by the pickup roller 142 one by one and conveying it toward the conveying roller pair 145. The conveying roller pair 145 is for conveying the recording paper P toward the registration roller pair 191.

[0022] The fixing unit 13 heats and presses the recording paper P on which the toner image is formed by the image forming unit 11 to fix the toner image on the recording paper P, and the recording paper P subjected to the fixing process is discharged to the discharge tray. The fixing unit 13 includes a fixing belt 131, a pressure roller 132, a heater 133, a pressing member 134, and a thermopile 135.

[0023] The fixing belt 131 is an endless belt, is formed in a substantially cylindrical shape extending in the longitudinal direction, and is configured to be rotatable around the axis. The fixing belt 131 is formed of, for example, a synthetic resin having heat resistance and elasticity.

[0024] Inside the fixing belt 131 are a heater 133 extending in the longitudinal direction of the fixing belt 131 and a pressing member 134. The heater 133 heats the circumferential surface of the fixing belt 131. The heater 133 is, for example, a halogen heater. The pressing member 134 is composed of a support member 134A and a pressing pad 134B. The pressing pad 134B is formed in a substantially rectangular parallelepiped shape extending in the longitudinal direction. The pressing pad 134B is fixed to the support member 134A and presses the fixing belt 131 toward the pressure roller 132.

[0025] The thermopile 135 is an infrared sensor that obtains a thermoelectric power proportional to the amount of infrared radiation incident on the light-receiving part, and is positioned near the circumferential surface of the fixing belt 131 to detect the temperature of the fixing belt 131. The pressure roller 132 is formed in a substantially cylindrical shape extending in the longitudinal direction and is configured to be rotatable around its axis. The pressure roller 132 is, for example, a metal cylinder covered with a layer made of synthetic resin or the like, and is pressed against the outer circumferential surface of the fixing belt 131, forming a nip portion N3 between the pressure roller and the fixing belt 131 through which the recording paper P to be fixed is inserted.

[0026] Furthermore, the pressure roller 132 is connected to a drive motor (not shown) via gears, etc., and rotates clockwise in the diagram, receiving the driving force from the drive motor. When the pressure roller 132 rotates, the fixing belt 131 follows the pressure roller 132 and rotates counterclockwise in the diagram.

[0027] The following describes the process when the image forming apparatus 1 performs document reading. The document reading unit 5 optically reads the image of the document supplied to it by the document feeding unit 6, or the document placed on the contact glass (not shown), and generates image data. The image data generated by the document reading unit 5 is stored in an image memory (not shown), etc.

[0028] The following describes the case in which an image forming operation is performed in the image forming apparatus 1. Based on the image data generated by the document reading operation, the image data stored in the image memory, and the image data received from an external device connected to the network (for example, a personal computer), the image forming unit 12 forms a toner image on the recording paper P, which is fed from the paper feeding unit 14, and performs printing.

[0029] Figure 3 is a functional block diagram schematically showing the main internal configuration of the image forming apparatus 1. Components similar to those shown in Figure 1 of the image forming apparatus 1 are denoted by the same reference numerals, and their detailed explanations are omitted. The image forming apparatus 1 comprises a controller unit 10, an engine unit 20, a document feeding unit 6, a document reading unit 5, a network interface unit 91, an operation unit 47, and a printer engine PE. The printer engine PE is a mechanism comprising an image forming unit 12, a fixing unit 13, a paper feeding unit 14, and a transport unit 19.

[0030] The network interface unit 91 is a communication interface that transmits and receives various types of data with external devices (e.g., personal computers) within the local area network or on the internet.

[0031] The operation unit 47 receives instructions from the operator, such as instructions to execute image forming operations, regarding various operations and processes that the image forming apparatus 1 can perform. The operation unit 47 is equipped with a display unit 473 that displays operation guidance to the operator. The operation unit 47 also receives input of instructions from the user based on user operations (touch operations) on the operation screen displayed on the display unit 473 or user operations on physical keys via the touch panel of the display unit 473.

[0032] The display unit 473 consists of an LCD (Liquid Crystal Display) or the like. The display unit 473 is equipped with a touch panel. When the operator touches a button or key displayed on the screen, the touch panel receives an instruction corresponding to the touched location.

[0033] The controller unit 10 and the engine unit 20 are each composed of, for example, a processor, RAM (Random Access Memory), ROM (Read Only Memory), and dedicated hardware circuitry. The processor is, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or an MPU (Micro Processing Unit). The controller unit 10 includes a controller control unit 100, and the engine unit 20 includes an engine control unit 200.

[0034] The controller unit 10 functions as a controller control unit 100 through the operation of the processor in accordance with software such as controller software stored on an HDD (Hard Disk Drive) or SSD (Solid State Drive), etc.

[0035] The engine unit 20 functions as an engine control unit 200 through operation by the processor in accordance with software such as engine software stored on an HDD or SSD.

[0036] However, the controller control unit 100 can be configured by hardware rather than by software operation by the controller unit 10, and the engine control unit 200 can be configured by hardware rather than by software operation by the engine unit 20. The same applies to each embodiment below unless otherwise specified.

[0037] The controller control unit 100 is responsible for the overall operation control of the image forming apparatus 1. The controller control unit 100 is connected to the document feeding unit 6, the document reading unit 5, the network interface unit 91, the operation unit 47, and the engine unit 20, and performs drive control of each of these units. For example, the controller control unit 100 requests printing from the engine unit 20 based on the image data to be printed. Examples of image data to be printed include image data obtained by reading by the document reading unit 5 and image data transmitted from a personal computer and received by the network interface unit 91.

[0038] The engine control unit 200 primarily controls the operation of the hardware. The engine control unit 200 is connected to the printer engine PE and performs drive control of each of these parts. For example, the engine control unit 200 controls the printer engine PE to feed recording paper P of a size specified by the printing conditions from the paper feed cassette 141 to the image forming unit 12 based on the size information of the recording paper P stored in each paper feed cassette 141, and to perform an image forming operation by having the image forming unit 12 form an image on the recording paper P based on the image data to be printed, and then transports the recording paper P with the formed image to the output tray and discharges it.

[0039] Next, an example of processing performed by the controller control unit 100 and the engine control unit 200 in the image forming apparatus 1 will be explained using the flowchart shown in Figure 4. This processing is performed when the controller control unit 100 receives a print job transmitted from an external device, for example, via the network interface unit 91.

[0040] The controller control unit 100 requests the engine control unit 200 to start the printer engine PE (S1).

[0041] When the engine control unit 200 receives a start request from the controller control unit 100, it starts a predetermined initial operation required before the start of execution of the print job (S2), and also starts a warm-up operation to raise the temperature of the fuser unit 13 to a predetermined target temperature G (S3), performing the initial operation and warm-up operation in parallel. The target temperature G is set within the range of the fixable temperature. If the fixable temperature is between 160°C and 200°C, for example, the target temperature G is set to the lowest temperature of 160°C.

[0042] The initial operations performed by the engine control unit 200 include, for example, operations other than the warm-up operation required before the start of execution of a print job, such as accessing the non-volatile memory of the image forming unit 12, reading the stored information (such as control parameters), and transmitting the read information to the controller control unit 100, as well as transmitting information such as the size of the recording paper P contained in each of the paper feed cassettes 141 to the controller control unit 100.

[0043] When the initial operation is complete, the engine control unit 200 sends a notification to the controller control unit 100 indicating that the initial operation is complete (S4), and requests the controller control unit 100 to send job information indicating the contents of the print job. Here, the time required to raise the temperature of the fuser unit 13 to the target temperature G is relatively long, and is assumed to be longer than the time required for the initial operation to be completed. In other words, the warm-up operation will not be completed before the initial operation is completed.

[0044] When the controller control unit 100 receives the above notification from the engine control unit 200, it transmits job information indicating the contents of the print job received from the external device to the engine control unit 200 (S5).

[0045] When the engine control unit 200 receives job information transmitted from the controller control unit 100, it starts executing the print job based on the received job information (S6).

[0046] Figure 5 shows an example of the control flow performed by the engine control unit 200 and the temperature change of the fuser unit 13. When the engine control unit 200 receives a request from the controller control unit 100 to start the printer engine PE, it performs the initial operation and warm-up operation in parallel, as explained in Figure 4. When the initial operation is completed (time TM1), it notifies the controller control unit 100 that the initial operation has been completed. Then, when the engine control unit 200 receives job information sent from the controller control unit 100 in response to the notification that the initial operation has been completed, it executes the print job based on the received job information. Note that the warm-up operation has not been completed at this point.

[0047] Specifically, the engine control unit 200 performs a "primary paper feeding" process to transport the recording paper P to a predetermined waiting position (nip section N2 by the register roller pair 191) on the transport path 190 leading to the image formation position (nip section N1) where an image is formed on the recording paper P in the image forming unit 12. Then, in accordance with the timing of image formation, it performs a "secondary paper feeding" process to transport the recording paper P waiting at the waiting position to the image formation position (nip section N1).

[0048] Furthermore, the engine control unit 200 forms a toner image on the intermediate transfer belt 125, feeds recording paper P from the paper feeding unit 14, performs an "image formation" process in the nip unit N1 to transfer the toner image to the recording paper P, performs a "fixing" process in the nip unit N3 by the fixing unit 13 to fix the toner image to the recording paper P, and then performs an "ejection" process to eject the recording paper P.

[0049] Here, the engine control unit 200 starts the image forming process before the warm-up operation is complete. That is, when the initial operation is completed, the engine control unit 200 starts executing a print job based on the job information for predetermined processes that can be executed even if the warm-up operation is not complete (image forming process, transport of recording paper P by the paper feeding unit 14 and transport unit 19).

[0050] Here, there is no problem if the recording paper P arrives at the nip section N3 after the temperature of the fuser section 13 has reached the target temperature G due to the warm-up operation described above (i.e., after time TM2). On the other hand, if the recording paper P arrives at the nip section N3 before the temperature of the fuser section 13 reaches the target temperature G, the fixing process may not be performed properly.

[0051] Therefore, the engine control unit 200 calculates a first required time L1, which is the time required for the temperature of the fuser unit 13 to reach the target temperature G from the start of the warm-up operation, based on, for example, the current temperature and the heating performance of the fuser unit 13. It also calculates a second required time L2, which is the time required for the recording paper P to arrive at the fuser unit 13 (nip unit N3) from the start of the image forming process, based on the recording paper transport speed by the paper feed unit 14 and the transport unit 19, the job information, and the image forming speed by the image forming unit 12. The engine control unit 200 further determines, based on the first required time L1 and the second required time L2, whether the time (timing) for the recording paper P to arrive at the fuser unit 13 has arrived by the time (timing) when the temperature of the fuser unit 13 reaches the target temperature G. The engine control unit 200 may use a predetermined required time as the first required time, or a predetermined transport time as the second required time L2.

[0052] If the engine control unit 200 determines that the time for the recording paper P to arrive at the fixing unit 13 will arrive before the time when the temperature of the fixing unit 13 reaches the target temperature G, it performs adjustment control to stop the transport of the recording paper P for at least the difference between the time when the recording paper P arrives at the fixing unit 13 and the time when the temperature of the fixing unit 13 reaches the target temperature G, so that the recording paper P arrives at the fixing unit 13 after the temperature of the fixing unit 13 has reached the target temperature G. In other words, the engine control unit 200 performs the above time adjustment if the recording paper P arrives at the fixing unit 13 before time TM2.

[0053] The second required time L2 varies depending on the size and thickness of the recording paper P, the location of the paper feed cassette 141 in which the recording paper P is stored, etc., so the engine control unit 200 calculates the second required time L2 taking these factors into consideration.

[0054] The engine control unit 200 performs the above-mentioned time adjustment, for example, by having the recording paper P wait at the standby position (nip section N2). In other words, the engine control unit 200 delays the start of the "secondary paper feeding" process and starts the "secondary paper feeding" process in accordance with the timing when the temperature of the fuser section 13 reaches the target temperature G.

[0055] For example, if the recording paper P arrives at the fuser unit 13 at time TM12 as shown in Figure 5, the recording paper P will arrive at the fuser unit 13 after the temperature of the fuser unit 13 has reached the target temperature G (after the warm-up operation is complete), so the above time adjustment is unnecessary. On the other hand, if the recording paper P arrives at the fuser unit 13 at time TM11 as shown in Figure 5, the recording paper P will arrive at the fuser unit 13 before the temperature of the fuser unit 13 has reached the target temperature G (before the warm-up operation is complete), so the above time adjustment is necessary.

[0056] Here, we will explain the control performed by a conventional engine control unit. Figure 6 shows an example of the control flow performed by a conventional engine control unit. In a conventional engine control unit, the initial operation is performed first, and after the initial operation is completed, a warm-up operation is performed, and after the warm-up operation is completed, a notification indicating the completion of the warm-up operation is sent to the controller control unit. Upon receiving the above notification, the controller control unit sends job information to the engine control unit, and upon receiving the job information sent from the controller control unit, the engine control unit starts executing the print job.

[0057] Therefore, as shown in Figure 6, conventional engine control units started executing print jobs only after the warm-up operation was complete, meaning the warm-up time was not effectively utilized. Furthermore, the initial operation and warm-up operation were not performed in parallel, resulting in poor efficiency.

[0058] In contrast, according to the above embodiment, it becomes possible to start executing a print job without waiting for the warm-up operation to complete. That is, during the warm-up operation (while the fuser unit 13 is heating up), it becomes possible to feed the recording paper P to the image forming unit 12 and form an image on the recording paper P. This makes it possible to effectively utilize the warm-up operation time and shorten the time required from the start of the printer engine PE to the completion of the print job compared to conventional methods.

[0059] In the above embodiment, the case where the target temperature G is fixed to the lowest possible fixing temperature is described. However, the appropriate fixing temperature varies depending on the size and thickness of the recording paper P, the transport speed, etc. Therefore, in another embodiment, the engine control unit 200 may take these factors into consideration and, based on the job information, calculate its own appropriate fixing temperature according to the print job indicated by the job information (for example, the size and / or type of recording paper), change the target temperature G to the calculated appropriate fixing temperature, and perform a warm-up operation. When the target temperature G is changed to the appropriate fixing temperature, as shown in the example in Figure 7, the time at which the warm-up operation is completed changes from time TM2 to time TM3.

[0060] In this alternative embodiment, the engine control unit 200 calculates the time required for the temperature of the fuser unit 13 to reach the unique appropriate fixing temperature as the first required time L1, and determines, based on the calculated time and the second required time L2, whether the time for the recording paper P to arrive at the fuser unit 13 has arrived by the time the temperature of the fuser unit 13 reaches the target temperature G (appropriate fixing temperature). This makes it possible to control the above-mentioned time required from the start of the printer engine PE until the completion of the print job more accurately according to the print content.

[0061] The present invention is not limited to the configuration of the above embodiments and various modifications are possible. Furthermore, the configuration and processing shown in the above embodiments using Figures 1 to 7 are merely one embodiment of the present invention and are not intended to limit the present invention to such configuration and processing. [Explanation of Symbols]

[0062] 1. Image forming apparatus 12 Image forming unit 13 Fixing section 19 Conveying section 100 Controller Control Unit 190 Conveyor path 200 Engine Control Unit PE Printer Engine

Claims

1. An image forming unit that forms an image on recording paper, A fixing unit for fixing the image formed in the image forming unit onto the recording paper, A paper feed cassette in which the aforementioned recording paper is stored, A transport unit that transports the recording paper from the paper feed cassette toward the image forming unit and the fixing unit, An engine control unit controls a printer engine comprising the image forming unit, the fixing unit, the paper feed cassette, and the transport unit to cause the image forming unit to form an image on the recording paper and the fixing unit to fix the image on the recording paper, thereby executing a print job. The system includes a controller control unit that requests the engine control unit to start the printer engine and transmits job information indicating the contents of the print job to the engine control unit, The engine control unit further, When the controller unit requests the printer engine to be started, the printer engine is controlled to perform, in parallel, a predetermined initial operation required before the start of execution of the print job and a warm-up operation to raise the temperature of the fuser unit to a predetermined target temperature. When the initial operation is completed, based on the job information, the image forming process by the image forming unit and the transport process of the recording paper by the transport unit are started as predetermined processes that can be executed even if the temperature of the fixing unit has not reached the target temperature, and when the temperature of the fixing unit reaches the target temperature, the fixing process by the fixing unit is executed. The engine control unit further calculates a first required time for the temperature of the fixing unit to reach the target temperature, and, based on the job information, calculates a second required time for the recording paper to arrive at the fixing unit. Based on the first required time and the second required time, it is determined whether the recording paper will reach the fixing unit before the temperature of the fixing unit reaches the target temperature. An image forming apparatus that, when it is determined that the recording paper will arrive at the fixing unit before the temperature of the fixing unit reaches the target temperature, stops the transport of the recording paper by the transport unit and performs adjustment control so that the timing of the recording paper's arrival at the fixing unit is after the temperature of the fixing unit has reached the target temperature.

2. When the initial operation is completed, the engine control unit notifies the controller control unit that the initial operation has been completed. The image forming apparatus according to claim 1, wherein when the controller control unit receives the notification indicating that the initial operation has been completed, it transmits the job information to the engine control unit.

3. The image forming apparatus according to claim 1 or 2, wherein the engine control unit calculates the first required time based on the current temperature of the fixing unit and the heating performance of the fixing unit, and calculates the second required time based on the job information, the attributes of the recording paper, the transport speed of the recording paper by the transport unit, and the position of the paper feed cassette.

4. The engine control unit performs primary paper feeding, which transports the recording paper to a predetermined waiting position on the transport path leading to the image formation position where an image is formed on the recording paper in the image forming unit. Subsequently, in accordance with the timing of image formation, it performs secondary paper feeding, which transports the recording paper waiting at the waiting position to the image formation position. The image forming apparatus according to claim 3, which performs the adjustment control by having the recording paper wait in the standby position when it is determined that the recording paper will arrive at the fixing unit before the temperature of the fixing unit reaches the target temperature.

5. The image forming apparatus according to any one of claims 1 to 4, wherein the engine control unit further calculates an appropriate fixing temperature corresponding to the print job indicated by the job information based on the attributes of the recording paper indicated by the job information, and changes the target temperature to the appropriate fixing temperature to perform the warm-up operation.

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