Image forming apparatus

Abstract

This invention provides a means to suppress misalignment of the printed image on pre-printed paper. [Solution] The image forming apparatus (100) includes a controller (200) that outputs image information, an image forming unit (107, 122) that forms an image on paper based on the image information output from the controller, a transport unit (105) that transports the paper to the image forming unit, one or more drive units (321) that are the drive source for the transport unit, and a printer control unit (201) that controls the drive unit, wherein the printer control unit corrects the transport speed of the transport unit based on information regarding the amount of image expansion and contraction notified by the controller (S102).

Description

Technical Field

[0001] The present invention relates to an image forming apparatus using an electrophotographic method.

Background Art

[0002] Conventionally, image forming apparatuses such as printers, copiers, and facsimiles can print an image on pre-printed paper on which forms, company names, logo marks, etc. are pre-printed. When printing an image on pre-printed paper, it is necessary to form a printed image with high positional accuracy with respect to the pre-printed image that has been pre-printed. Therefore, the user finely adjusts the arrangement of the printed image and gives a print instruction so that the printed image is printed at a desired position on the pre-printed paper.

[0003] By the way, even when giving a print instruction for the same image, the degree of stretching and shrinking of the image may be slightly different for each image forming apparatus. For example, when changing the image forming apparatus used by replacing the image forming apparatus or the like, the degree of stretching and shrinking of the image with respect to the conveyance direction of the printed image may change. In this case, there is a possibility that the printing positions of the pre-printed image and the printed image may be slightly shifted.

[0004] Patent Document 1 discloses an image forming apparatus that changes the degree of stretching and shrinking of an image printed on a sheet by adjusting the rotation speed of a polygon mirror in a laser scanner unit.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 modifies image scaling by adjusting the rotation speed of a polygon mirror in a laser scanner unit, but depending on the hardware configuration of the laser scanner unit, image quality may be reduced. Another possible method to suppress the misalignment of the print position between preprinted and printed images is to enlarge or reduce the image data instructed to be printed by the printer's controller. However, adopting such a method increases the load on the controller, takes longer for image processing, and may result in decreased productivity.

[0007] The present invention aims to provide an image forming apparatus capable of printing images with good positional accuracy while suppressing a decrease in productivity. [Means for solving the problem]

[0008] To achieve the above objective, the image forming apparatus of the present invention is characterized by comprising: a controller that outputs image information; an image forming unit that forms an image on paper based on the image information output from the controller; a transport unit that transports the paper to the image forming unit; and a speed correction unit that corrects the transport speed of the paper transported by the transport unit based on information regarding the amount of expansion and contraction of the image notified by the controller. [Effects of the Invention]

[0009] According to the present invention, images can be printed with good positional accuracy while suppressing a decrease in productivity. [Brief explanation of the drawing]

[0010] [Figure 1] Cross-sectional view of the image forming apparatus related to Example 1 [Figure 2] Hardware configuration diagram of the image forming apparatus related to Example 1 [Figure 3] Control block diagram related to Example 1 [Figure 4]Flowchart of the control system related to Example 1 [Figure 5] Cross-sectional view of the image forming apparatus and post-processing apparatus related to Example 2 [Figure 6] Hardware configuration diagram of the post-processing device related to Example 2 [Figure 7] Control block diagram related to Example 2 [Figure 8] Control flowchart related to Example 2 [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted. [Examples]

[0012] <Image Formation Process> Figure 1 is a schematic diagram of a printer 100, which is an example of an image forming apparatus. In Figure 1, the printer 100 has the following elements as components of the image forming section that forms an image on paper. The photosensitive drum 122, which serves as an image carrier composed of an organic photoreceptor or amorphous silicon photoreceptor, is rotated at a predetermined peripheral speed (process speed) in the clockwise direction in Figure 1. The peripheral surface of the photosensitive drum 122 is uniformly charged to a predetermined polarity and potential by a charging roller 123. The peripheral surface of the photosensitive drum 122 is also irradiated with laser light emitted from a laser diode placed in a laser optical box 109, which is polarized by a reflective mirror 108. The controller 200 (see Figures 2 and 3) converts image information transmitted from the host computer 203 into a time-series electrodigital pixel signal (hereinafter referred to as a video signal). Scanning exposure is performed by irradiating the surface with a modulated (on / off converted) laser light corresponding to the converted pixel signal. As a result, an electrostatic latent image corresponding to the image information is formed on the peripheral surface of the photosensitive drum 122. The electrostatic latent image formed in this manner, corresponding to the target image, is developed as a toner image by the developer unit 121.

[0013] The paper feed roller 142 is a paper feed unit that feeds the recording paper placed on the paper feed tray (stacking unit) 140 to the separation roller 143. The separation roller 143 separates the supplied recording paper one sheet at a time and supplies it to the transport roller 105, which is an example of a transport unit. The recording paper supplied to the transport roller 105 is transported to the photosensitive drum 122. A toner image developed on the photosensitive drum 122 is formed on the recording paper. At this time, the transfer roller 107 supplies a charge of opposite polarity to the toner from the back of the recording paper, thereby transferring the toner image from the photosensitive drum 122 to the recording paper. The recording paper that has received the toner image transfer in this way is separated from the photosensitive drum 122 and sent to the fuser 130, where the toner image is heat-fixed. The heat-fixed recording paper is transported by the paper discharge roller 112 and discharged to the paper discharge tray 115.

[0014] <Hardware Configuration Diagram> Figure 2 is a diagram showing the hardware configuration of the printer 100. The engine control unit 201 executes a program stored in a ROM (not shown) and controls the printer 100 by operating each drive circuit in the image forming unit. The conveyance motor 321 is a drive unit driven via the conveyance motor drive circuit 311. Similarly, the paper feed solenoid 322 can be switched between ON and OFF via the paper feed solenoid drive circuit 312. The conveyance motor 321 rotates the rollers of the photosensitive drum 122, the developing unit 121, the charging roller 123, the conveyance roller 105, the fixing unit 130, and the paper discharge roller 112. The paper feed roller 142 and the separation roller 143 use the conveyance motor 321 as a drive source and rotate when the paper feed solenoid 322 is turned ON.

[0015] The conveyance sensor 110 is a detection unit that detects the presence or absence of recording paper on the conveyance path. The detection result of the presence or absence of paper is transmitted to the engine control unit 201 via the conveyance sensor input circuit 316. The paper discharge sensor 111 detects the presence or absence of recording paper on the conveyance path. The detection result of the presence or absence of paper is transmitted to the engine control unit 201 via the paper discharge sensor input circuit 317.

[0016] The controller 200 communicates with the engine control unit 201 via a communication port (not shown) and outputs image information and various other information. For example, it transmits and receives information such as the type of recording paper, including the size of the recording paper, the thickness and basis weight of the recording paper.

[0017] <Control Content> Figure 3 is a control block diagram of Example 1. The controller 200 gives a print instruction to the engine control unit 201 according to an instruction from the host computer 203. Specifically, the controller 200 receives image information and a print command from the host computer 203, analyzes the received image information, converts it into bit data, and notifies the engine control unit 201 of the print command and the video signal for each sheet of recording paper. The print command sent from the controller 200 includes the paper type information of the recording paper to be printed and the size of the recording paper. Also, the controller 200 receives from the user, via the host computer 203, the amount of scaling correction when stretching or shrinking the image in the conveyance direction, and whether to perform the correction for stretching or shrinking in the conveyance direction for the print command instructed by the user. The scaling correction amount specifying unit 205 of the controller 200 notifies the engine control unit 201 of the amount of scaling correction [%] when stretching or shrinking the image received from the user in the conveyance direction. For example, when printing with a 5 mm margin provided at the front and rear ends in the conveyance direction on A4 paper, the printer 100 should eject a sheet on which an image of 287 mm is printed. On the other hand, assume that a sheet on which an image with only a 4 mm margin at the rear end is printed is actually ejected. In other words, assume that a sheet on which an image of 288 mm is printed is ejected. In this case, in order to shrink the image by 1 mm, the scaling correction amount specifying unit 205 notifies the engine control unit 201 of 99.653% (287 mm ÷ 288 mm).

[0018] The correction validity unit 204 of the controller 200 notifies the engine control unit 201 of the information on whether to perform the correction for stretching or shrinking received from the user. The engine control unit 201 performs an image forming process based on the print command, the amount of scaling correction, and the presence or absence of correction execution received from the controller 200.

[0019] The speed determination unit 206 determines the transport speed of the recording paper to be transported to the image forming unit based on the type and size of the recording paper when starting the image forming process. For example, if the recording paper is thick paper, the amount of heat absorbed by the fuser 130 is greater. In order to sufficiently heat-fix the toner image, the fuser 130 needs to heat and fix the recording paper for a long time. Therefore, the speed determination unit 206 slows down the transport speed for thick paper compared to plain paper. The speed determination unit 206 also switches the transport speed according to the width of the paper. The heat emitted by the fuser 130 is absorbed by the paper through the rollers of the fuser 130. The wider the recording paper, the larger the contact area between the rollers of the fuser 130 and the recording paper, so the heat is more easily absorbed by the recording paper. Conversely, the narrower the paper width, the smaller the contact area between the rollers of the fuser 130 and the recording paper, so the heat is less easily absorbed by the recording paper. Therefore, the narrower the recording paper, the more heat tends to accumulate on the rollers. To prevent problems caused by excessive heat buildup on the rollers, the engine control unit 201 reduces the amount of heat generated by the fuser unit 130 when the paper width is too narrow. Even with the reduced amount of heat, the speed determination unit 206 slows down the transport speed when the paper width is narrow in order to ensure that the fuser unit 130 is sufficiently heat-fixed toner.

[0020] Specifically, if the basis weight of the recording paper is 80 g / cm² or less and the paper width is 180 mm or more, the speed determination unit 206 sets the transport speed to 300 mm / s. If the above conditions are not met, the transport speed is set to 200 mm / s.

[0021] The speed correction unit 207 corrects the transport speed determined by the speed determination unit 206 based on the information regarding the amount of image stretching / contraction notified by the stretching / contraction correction amount specification unit 205. For example, if the speed determination unit 206 determines the transport speed to be 300 mm / s and the stretching / contraction correction amount specification unit 205 notifies it of 99%, the transport speed is corrected to 297 mm / s. In this case, the engine control unit 201 transports the paper at 297 mm / s during the printing operation. In this embodiment, the amount of image stretching / contraction is notified in units of [%], but the information regarding the amount of stretching / contraction may also be notified in units of [mm].

[0022] The paper feed timing control unit 208 is a control unit that turns on the paper feed solenoid 322 at desired time intervals. For example, in the first embodiment, the printer 100 requires a minimum paper spacing of 30 mm when printing continuously, due to the shape of the transport sensor 110. Therefore, when continuously printing paper with a length of 270 mm, the paper feed timing control unit 208 turns on the paper feed solenoid 322 every 300 mm of transport. If the transport speed is 300 mm / s, the paper feed timing control unit 208 turns on the paper feed solenoid 322 every 1000 ms.

[0023] The image formation start timing determination unit 209 instructs the controller 200 to start sending a video signal at a predetermined timing so that the leading edge of the image printed by the printer 100 matches the leading edge of the transported paper. This instruction corresponds to the timing of image formation start. For example, suppose the distance between the position where the laser light output from the laser optical box 109 (represented by D1 in Figure 1) irradiates the photosensitive drum 122 and the nip position between the photosensitive drum 122 and the transfer roller 107 is 97 mm. Furthermore, suppose the distance between the nip position between the photosensitive drum 122 and the transfer roller 107 (represented by D2 in Figure 1) and the transport sensor 110 is 100 mm. In this case, since the difference between D2 and D1 is 3 mm, the image formation start timing determination unit 209 instructs the controller 200 to start sending a video signal at the timing when the transport sensor 110's detection state changes from "no paper" to "paper present" and the paper has been transported 3 mm. As a result, the leading edge position of the printed image matches the leading edge position of the paper. Assuming a transport speed of 300 mm / s, the image creation start timing determination unit 209 instructs the controller 200 to start sending the video signal 10 ms after the transport sensor 110 detects the presence of paper.

[0024] The paper length calculation unit 210 is a calculation unit that calculates the length of the paper in the transport direction when it is transported to the printer 100. The paper length calculation unit 210 calculates the length of the paper from the time it takes for the transport sensor 110's detection state to change from "paper present" to "no paper present". For example, if printing is being done at a transport speed of 300 mm / s and the time is 900 ms, the paper length calculation unit 210 calculates the paper length to be 270 mm.

[0025] The paper jam detection unit 211 is a unit that determines whether a paper jam has occurred during printing. If the detection state of the paper ejection sensor 111 does not change from "no paper" to "paper present" even after a predetermined time has elapsed since the detection state of the transport sensor 110 changed from "no paper" to "paper present", the paper jam detection unit 211 determines that a paper jam has occurred. Specifically, if the distance between the transport sensor 110 and the paper ejection sensor 111 is 210 mm and the transport speed is 300 mm / s, it can be assumed that the transport time between the sensors is 700 ms. A 10% margin is added to account for transport errors, etc. In other words, the paper jam detection unit 211 determines that a paper jam has occurred if the detection state of the paper ejection sensor 111 does not change from "no paper" to "paper present" even after 770 ms has elapsed since the detection state of the transport sensor 110 changed from "no paper" to "paper present".

[0026] When stretching or compressing an image in the transport direction, the engine control unit 201 performs the following control. When the engine control unit 201 receives a print command from the controller 200, it starts processing the flowchart in Figure 4. Each step in the flowchart in Figure 4 is executed by the engine control unit 201.

[0027] In S100, the speed determination unit 206 determines the transport speed of the recording paper to be transported to the image forming unit based on the type and size of the recording paper. The details of this determination process are as described above and will be omitted here, but in this embodiment, when printing on A4 plain paper, the transport speed is set to 300 mm / s.

[0028] Next, in S101, the engine control unit 201 determines whether or not to perform image stretching correction based on the information regarding the amount of image stretching notified by the controller 200 along with the image information. Specifically, if the controller 200 receives a notification from the correction activation unit 204 to disable the correction (i.e., a notification that image stretching correction will not be performed), the engine control unit 201 decides not to perform image stretching correction. Also, if the notification received from the stretching correction amount specification unit 205 is 100%, the engine control unit 201 decides not to perform image stretching correction. If it is decided in S101 not to perform image stretching correction, the process proceeds to S108. The various controls when image stretching correction is not performed are as described above.

[0029] On the other hand, if it is determined in S101 to perform image stretching correction, the process proceeds to S102. In S102, the speed correction unit 207 corrects the transport speed during printing, which was determined in S101, based on the information regarding the amount of image stretching notified by the controller 200. For example, if the notification received from the stretching correction amount specification unit 205 is 99%, the speed correction unit 207 corrects the transport speed to 297 mm / s, which is 99% of 300 mm / s, in order to shrink the image. The process then proceeds to S103.

[0030] In S103, the engine control unit 201 determines whether the speed correction performed in S102 is a correction that increases the transport speed. If it is a correction that increases the transport speed, the engine control unit 201 proceeds to S105 without performing the paper feed timing correction in S104. The reason for not performing the paper feed timing correction is as follows: If the transport speed is increased and the paper feed timing is not corrected, the distance between sheets of paper during continuous printing will increase compared to when the transport speed is not corrected. If the paper feed timing is increased to prevent the distance between sheets of paper from increasing, the time between sheets of paper will decrease. If the time between sheets of paper is decreased, the heat storage in the fuser 130 that occurs between sheets of paper will be insufficient, and the fuser 130 will not be able to perform proper thermal fixing. Therefore, if it is determined in S103 to increase the transport speed, the paper feed timing control unit 208 does not correct the paper feed timing and proceeds to S105.

[0031] On the other hand, if the transport speed is slowed down in S103, the process proceeds to S104. In S104, the paper feed timing control unit 208 corrects the paper feed timing so that the gap between sheets of paper is at least 30 mm. In the following explanation, it is assumed that the notification received from the expansion / contraction correction amount specification unit 205 is 99% and the paper length is 270 mm. The paper feed timing control unit 208 corrects the paper feed timing so that paper is fed every 300 mm of transport at a speed of 299 mm / s. Therefore, the paper feed timing control unit 208 changes the paper feed timing to 1003.3 ms.

[0032] Next, the engine control unit 201 corrects the image formation timing in S105. The image formation start timing determination unit 209 determines the timing to instruct the controller 200 to start sending the video signal during printing, in accordance with the corrected transport speed. Specifically, the timing when 3 mm has been transported at 299 mm / s, that is, the time from when the transport sensor 110 detects the presence of paper until the controller 200 is instructed to start sending the video signal, is set to 10.03 ms. As a result, the leading edge registration distance from the leading edge of the paper to the leading edge of the image becomes the same distance (predetermined distance) as when the transport speed is not corrected.

[0033] The process then proceeds to S106. In S106, the paper length calculation unit 210 adjusts the paper length calculation formula to match the corrected transport speed. Therefore, if the time from when the transport sensor 110 detects paper to when it is not detected until it is 900 ms, the paper length calculation unit 210 calculates that the paper length is 269.1 mm. Similarly, if the time is 903 ms, the paper length calculation unit 210 calculates that the paper length is 270 mm. As a result, the paper length calculation unit 210 can correctly calculate the paper length even when the speed correction unit 207 corrects the transport speed.

[0034] The process then proceeds to S107. In S107, the paper jam detection unit 211 corrects the timing at which it determines a paper jam during printing, in accordance with the corrected transport speed. Specifically, the paper jam detection unit 211 determines the timing at which it determines a paper jam has occurred by calculating the time it takes to transport 210 mm, the distance between the transport sensor 110 and the paper discharge sensor 111, at a speed of 299 mm / s, and then adding a 10% margin to the calculation result. In other words, it sets the time to 210 mm ÷ 299 mm / s × 1.1 = 772.6 mm. Therefore, the paper jam detection unit 211 determines a paper jam has occurred if 772.6 ms has elapsed since the detection state of the transport sensor 110 changed from no paper to paper present, and the detection state of the paper discharge sensor 111 has not changed from no paper to paper present. The process then proceeds to S108, and the engine control unit 201 starts printing.

[0035] When printing starts in S108, the process shown in the flowchart in Figure 4 is completed. Subsequently, the engine control unit 201 rotates the transport motor 321 at a speed that results in a transport speed of 299 mm / s.

[0036] As explained above, when the engine control unit 201 receives information regarding the amount of image stretching from the controller 200, it corrects the transport speed according to the instructions given by the correction activation unit 204 and the stretching correction amount specification unit 205. This changes the degree of stretching in the transport direction of the printed image, thereby reducing the misalignment of the print position between the preprinted image printed on the preprint paper and the printed image.

[0037] Furthermore, according to this embodiment, by executing the processes S103 to S107, the engine control unit 201 can reduce the adverse effects caused by switching the transport speed.

[0038] In this embodiment, the stretch / contraction correction amount specification unit 205 is configured to notify the ratio [%] when stretching the image in the transport direction. However, the present invention is not limited thereto. For example, the stretch / contraction correction amount specification unit 205 may be configured to notify the amount [mm] to stretch or contract. In this case, the speed correction unit 207 calculates the transport speed correction rate [%] based on the paper size being fed and the information notified by the stretch / contraction correction amount specification unit 205, and corrects the transport speed. This achieves the same effect as described in this embodiment.

[0039] Furthermore, while Embodiment 1 shows a configuration in which all rollers are driven by a single drive source, the present invention is not limited to this configuration. For example, the printer 100 may have a configuration consisting of multiple drive sources, such as a configuration in which the developing machine 121 and the photosensitive drum 122 have different drive sources. In this case, the speed correction unit 207 corrects the speed for each drive source. This makes it possible to obtain the same effect as described in this embodiment. In a configuration consisting of multiple drive sources, the correction magnification ratios for each drive source do not have to be the same. The correction amount for each drive source may be adjusted considering the influence that each drive source has on the printing operation. [Examples]

[0040] Example 1 describes a method to reduce the misalignment of the printing position between the preprinted image printed on the preprinted paper and the printed image by changing the paper transport speed and stretching the printed image in the transport direction. Example 2 describes a configuration in which the post-processing device is connected to the image forming apparatus.

[0041] As shown in Figure 5, a post-processing device 150, such as a stapler or puncher, may be connected to the printer 100. When the post-processing device 150 is connected to the printer 100, simply changing the transport speed of the printer 100, as in Example 1, will not result in good printing performance. Specifically, during the period when the paper is transported while being sandwiched between the roller driven by the printer 100 (hereinafter referred to as roller A) and the roller driven by the post-processing device 150 (hereinafter referred to as roller B), if the transport speeds of roller A and roller B are different, wrinkles or damage may occur to the paper. More specifically, if the transport speed of roller A is faster than that of roller B, roller A will push the paper in, causing the paper to bend between roller A and roller B. The bent parts of the paper may collide with components of the post-processing device or image forming device, potentially causing damage to the paper. Alternatively, if the paper bends beyond a certain point, creases may form in the paper. Conversely, if the transport speed of roller B is faster than that of roller A, roller B will pull the paper. This may cause scratches on the paper caused by roller B or roller A.

[0042] The following describes how to ensure good printing operation even when the post-processing unit 150 is connected to the printer 100.

[0043] <Image Formation Process> Figure 5 illustrates the image formation process in Example 2. Components identical to those in the previous example are numbered the same as in Figure 1 and their explanations are omitted. The post-processing device 150 is a device that performs post-processing such as stapling and punching on paper transported from the printer 100. The paper output switching flapper 151 is a flapper that switches whether the paper is ejected to the paper output tray 115 or transported to the post-processing device 150. Depending on whether or not post-processing is to be performed on the paper, the post-processing device 150 changes the destination of the paper by switching the paper output switching flapper 151. Paper transported to the post-processing device 150 is gripped and transported by the receiving roller 152. After the paper transported by the receiving roller 152 is subjected to stapling and punching by the post-processing device 150, it is discharged to the second paper output tray 153.

[0044] <Hardware Configuration Diagram> Figure 6 shows the hardware configuration of the post-processing device 150 of Embodiment 2. The post-processing control unit 400 controls the post-processing of the paper transported from the printer 100 by operating each drive circuit. The post-processing transport motor 421 is an example of a post-processing drive unit and is driven via the post-processing transport motor drive circuit 511. The post-processing transport motor 421 rotates the receiving roller 152. The receiving roller 152 is an example of a post-processing transport unit. The paper output switching flapper 151 is driven via the flapper drive circuit 512.

[0045] The controller 200 communicates with the post-processing control unit 400 via a communication port (not shown) and notifies it of various information. For example, information such as the size of the recording paper and the type of recording paper, including its thickness and basis weight, is transmitted between the controller 200 and the post-processing control unit 400. The post-processing control unit 400 also communicates with the engine control unit 201 via the controller 200.

[0046] <Control details> Figure 7 is a control block diagram of Embodiment 2. Note that components performing the same processing as in Embodiment 1 are omitted from the illustration and description. The user notifies the forming controller 200 of post-processing requests, such as stapling or punching, to the printing paper via the host computer 203. The controller 200 notifies the post-processing control unit 400 of the post-processing details notified by the user. After notifying the post-processing details, the controller 200 issues a print command to the engine control unit 201. The speed notification unit 220 notifies the post-processing control unit 400 of the paper transport speed via the controller 200. The post-processing speed control unit 401 switches the speed at which the receiving roller 152 transports the paper by switching the rotation speed of the post-processing transport motor 421. The post-processing control unit 400 performs stapling and punching on the transported paper using a stapling control unit (not shown) and a punching control unit (not shown).

[0047] When the engine control unit 201 receives a print command from the controller 200, it starts the flowchart shown in Figure 8. Note that for processes identical to those in Example 1, the same numbers are assigned, and their explanations are omitted.

[0048] In steps S100 to S102, the speed determination unit 206 and the speed correction unit 207 determine the transport speed of the printer 100 in the same manner as in Embodiment 1. Then, in S109, the transport control is corrected. Specifically, the same control as in S103 to S107 in Figure 4 is performed, and then the process proceeds to S110. In S110, the speed notification unit 220 notifies the post-processing control unit 400 of the transport speed determined in S100 to S102 via the controller 200. The post-processing speed control unit 401 rotates the post-processing transport motor 421 based on the speed notified by the speed notification unit 220. The process then proceeds to S108, where the engine control unit 201 starts printing. Printing starts in S108.

[0049] After printing and heat-fixing the paper in the fuser 130, it is transported to the receiving roller 152. The receiving roller 152 rotates at the same transport speed as the rollers of the fuser 130. Subsequently, the paper is transported to the post-processing device 150, where it undergoes post-processing such as stapling and punching, and is then discharged into the second output tray 153.

[0050] As explained above, according to this embodiment, in a configuration in which the post-processing device 150 is connected to the printer 100, matching the transport speed of the printer 100 with the transport speed of the post-processing device 150 makes it possible to perform good printing operations that reduce wrinkles and scratches on the paper.

[0051] [Other embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0052] This embodiment includes the following configuration.

[0053] (Composition 1) A controller that outputs image information, An image forming unit that forms an image on paper based on image information output from the controller, The image forming unit includes a transport unit for transporting the paper, A speed correction unit corrects the transport speed of the paper transported by the transport unit based on information regarding the amount of image stretching notified from the controller, An image forming apparatus characterized by having the following features.

[0054] (Configuration 2) The image forming apparatus according to configuration 1, wherein the controller has a designation unit that specifies the amount of image stretching or shrinking based on user instructions, and notifies the specified amount of image stretching or shrinking.

[0055] (Composition 3) The image forming apparatus according to configuration 1 or 2, wherein the controller has a correction enabling unit that specifies whether or not to enable image stretching correction, and when it is specified that image stretching correction should be enabled, it notifies information regarding the amount of image stretching.

[0056] (Composition 4) A paper feeding unit that feeds paper placed on the loading unit toward the image forming unit, A paper feed timing control unit that changes the timing at which the paper is fed from the paper feed unit when the speed correction unit corrects the paper transport speed, An image forming apparatus according to any one of configurations 1 to 3, characterized by having the following features.

[0057] (Composition 5) The image forming apparatus according to any one of configurations 1 to 4, characterized in that when the speed correction unit corrects the paper transport speed, it has an image formation start timing determination unit that determines the image formation start timing to instruct the controller so that the distance between the leading edge of the paper in the transport direction and the leading edge position of the image formed on the paper becomes a predetermined distance.

[0058] (Composition 6) A detection unit for detecting the presence or absence of paper being transported by the transport unit, The system includes a paper length calculation unit that calculates the length of the paper in the transport direction based on the time the detection unit detected the paper, The image forming apparatus according to any one of configurations 1 to 5, characterized in that the paper length calculation unit changes the calculation formula of the paper length calculation unit when the speed correction unit corrects the paper transport speed.

[0059] (Composition 7) A detection unit for detecting the presence or absence of paper being transported by the transport unit, The system includes a paper jam detection unit that determines the occurrence of a paper jam based on the paper detection result by the aforementioned detection unit, The image forming apparatus according to any one of configurations 1 to 6, characterized in that the paper jam detection unit changes the timing at which it determines that a paper jam has occurred when the speed correction unit corrects the paper transport speed.

[0060] (Composition 8) A post-processing transport unit that transports the paper transported from the image forming unit, The post-processing drive unit is the drive source for the post-processing transport unit, It includes a post-processing control unit that controls the post-processing drive unit, The post-processing control unit, A post-processing apparatus according to any one of configurations 1 to 7, characterized in that, upon receiving information regarding the paper transport speed corrected by the speed correction unit, the drive of the post-processing drive unit is controlled so that the transport speed of the post-processing transport unit becomes the same as the transport speed of the transport unit.

[0061] (Composition 9) An image forming apparatus according to any one of configurations 1 to 8, characterized by comprising one or more drive units which are the drive source for the transport unit.

[0062] (Composition 10) The image forming apparatus according to any one of configurations 1 to 9, characterized in that the controller notifies the speed correction unit of image information corresponding to the image. [Explanation of symbols]

[0063] 100 printers 105 Conveyor rollers 107 Transfer Roller 108 Reflective Mirror 109 Laser Optical Box 110 Transport Sensor 111 Paper output sensor 112 Paper output roller 115 Paper output tray 121 Developer 122 Photosensitive drum 123 Electrostatic roller 130 Fuser 140 Paper feed tray 142 Paper feed roller 143 Separation Roller 150 Post-processing equipment 151 Paper output switching flapper 152 Accepting roller 153 Second paper output tray 200 controllers 201 Engine Control Unit 203 Host Computer 204 Correction effective area 205 Expansion / contraction correction amount specification section 206 Speed ​​determination section 207 Speed ​​correction section 208 Paper feed timing control unit 209 Image creation start timing determination unit 210 Paper length calculation section 211 Paper jam detection unit 220 Speed ​​notification section 321 Conveyor motor 322 Paper feed solenoid 400 Post-processing control unit 421 Post-processing transport motor 511 Post-processing transport motor drive circuit 512 Flapper drive circuit

Claims

1. A controller that outputs image information, An image forming unit that forms an image on paper based on image information output from the controller, The image forming unit includes a transport unit for transporting the paper, A speed correction unit corrects the transport speed of the paper transported by the transport unit based on information regarding the amount of image stretching notified from the controller, An image forming apparatus characterized by having the following features.

2. The image forming apparatus according to claim 1, wherein the controller has a designation unit that specifies the amount of image stretching or shrinking based on user instructions, and notifies the specified amount of image stretching or shrinking.

3. The image forming apparatus according to claim 1, wherein the controller has a correction enabling unit that specifies whether or not to enable image stretching correction, and when it is specified that image stretching correction should be enabled, it notifies information regarding the amount of image stretching.

4. A paper feeding unit that feeds paper placed on the loading unit toward the image forming unit, A paper feed timing control unit that changes the timing at which the paper is fed from the paper feed unit when the speed correction unit corrects the paper transport speed, The image forming apparatus according to claim 1, characterized by having the following features.

5. The image forming apparatus according to claim 1, further comprising an image formation start timing determination unit that determines the image formation start timing to instruct the controller so that the distance between the leading edge of the paper in the paper transport direction and the leading edge position of the image formed on the paper becomes a predetermined distance when the speed correction unit corrects the paper transport speed.

6. A detection unit for detecting the presence or absence of paper being transported by the transport unit, The system includes a paper length calculation unit that calculates the length of the paper in the transport direction based on the time the detection unit detected the paper, The image forming apparatus according to claim 1, characterized in that the paper length calculation unit changes the calculation formula of the paper length calculation unit when the speed correction unit corrects the paper transport speed.

7. A detection unit for detecting the presence or absence of paper being transported by the transport unit, The system includes a paper jam detection unit that determines the occurrence of a paper jam based on the paper detection result by the aforementioned detection unit, The image forming apparatus according to claim 1, characterized in that the paper jam detection unit changes the timing at which it determines that a paper jam has occurred when the speed correction unit corrects the paper transport speed.

8. A post-processing transport unit that transports the paper transported from the image forming unit, The post-processing drive unit is the drive source for the post-processing transport unit, It includes a post-processing control unit that controls the post-processing drive unit, The post-processing control unit, The post-processing apparatus according to claim 1, characterized in that, upon receiving information regarding the paper transport speed corrected by the speed correction unit, it controls the drive of the post-processing drive unit so that the transport speed of the post-processing transport unit becomes the same as the transport speed of the transport unit.

9. The image forming apparatus according to claim 1, characterized in that it comprises one or more drive units which are the drive source for the transport unit.

10. The image forming apparatus according to claim 1, characterized in that the controller notifies the speed correction unit of image information corresponding to the image.

Images