JP2013182039A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a processing time from creation of image data to transfer of a toner image to a sheet.SOLUTION: In a compound machine, a sheet conveyance time TS to convey a sheet material 16 from a supply tray 14 to a transfer position P1 is longer than image transfer times TZy and TZb to convey an electrostatic latent image and a toner image from an irradiation position P2 to a transfer position P1. In the compound machine, conveyance of the sheet material 16 is started before completion of creation of image data for respective colors used in forming an electrostatic latent image at the transfer position P1. Accordingly, a processing time from creation of image data for respective colors to transfer of the toner image to the sheet material 16 can be reduced.

Description

  The invention disclosed in the present specification relates to a technique used in an image forming apparatus that transports a transfer image and a sheet to a transfer position, transfers the transfer image to the sheet at the transfer position, and forms an image.

  Conventionally, in an image forming apparatus, for example, a toner image is formed on a photoconductor, and the toner image is conveyed to a transfer position using the photoconductor and an intermediate transfer belt. Separately, the paper stored in the recording medium storage unit is conveyed to a transfer position by a roller. The toner image and the paper are conveyed to the transfer position at the same timing, and the toner image is transferred to the paper at the transfer position. In the prior art, in order to transport the paper to the transfer position at an appropriate timing, the transport of the paper is started after the creation of the image data necessary for forming the toner image is completed and the toner image can be formed. Is disclosed (for example, Patent Document 1).

JP 2008-152079 A

  However, depending on the structure of the image forming apparatus, the transport time required for transporting the paper may be longer than the transport time required for transporting the toner image. Therefore, when the conveyance of the paper is started after waiting for the creation of the image data as in the prior art, the toner image over a time corresponding to the time difference between the conveyance time of the paper and the conveyance time of the toner image after the completion of the creation of the image data. Therefore, there is a problem that the processing time from the creation of the image data to the transfer of the toner image onto the paper is prolonged.

  The invention disclosed in this specification discloses a technique for shortening a processing time from creation of image data to transfer of a toner image onto a sheet.

  The image forming apparatus disclosed in this specification includes an image forming unit that forms a transfer image using image data, and the transfer image is formed at an image forming position facing the image forming unit, and carries the transfer image. And an image carrier for conveying the transfer image to a transfer position different from the image forming position, a supply unit on which the sheet is placed, and the sheet placed on the supply unit to the transfer position. A sheet conveying time in which the conveyance unit conveys the sheet from the supply unit to the transfer position, and the image carrier transfers the transfer image from the image forming position to the transfer position. The control section starts image data creation processing for creating the image data, and transport of the sheet before the creation of the image data is completed, and the sheet and the transfer image Was reached the transfer position at the same time, it executes the image forming process of transferring the transfer image to the sheet at the transfer position.

  In this image forming apparatus, since the conveyance of the sheet is started before the creation of the image data is completed, compared to the conventional technique in which the conveyance of the sheet is started after the creation of the image data is completed, the image data is created from the creation of the sheet. The time until the toner is conveyed to the transfer position is shortened, and the processing time from the creation of the image data to the transfer of the toner image onto the sheet can be shortened.

  In the above image forming apparatus, there are a plurality of at least one of the image forming unit and the supply unit, and the control unit determines that a difference between the sheet conveying time and the image conveying time is a first time difference. A first control mode in which image forming processing is performed using a combination of the supply unit and the image forming unit, and the difference between the sheet transport time and the image transport time is the first time difference. The image forming process is performed using the combination of the supply unit and the image forming unit in which the difference between the sheet conveying time and the image conveying time is a second time difference larger than the first time difference without using a combination of forming units. A time period from the start of the image data creation process to the start of sheet conveyance in the second control mode is from the start of the image data creation process to the first control mode. It may be shorter configuration than the time until the start of conveyance of the sheet in the de.

  According to this image forming apparatus, the difference between the sheet conveyance time and the image conveyance time is larger than that in the first control mode, and the time from the creation of the image data to the conveyance of the sheet to the transfer position is extended. In the control mode, the time from the start of image data creation processing to the start of sheet conveyance is made shorter than in the first control mode, so that the processing time can be shortened in the second control mode.

  Further, the image forming apparatus includes a plurality of the image forming units, and the control unit, in the first control mode, is mounted on the upstream side in the conveyance direction of the transfer image or the sheet. An image forming process is performed using an image forming unit, and in the second control mode, an image forming process is performed using the downstream image forming unit placed on the downstream side of the plurality of image forming units, The time from the start of the image data creation process to the start of conveyance of the sheet in the second control mode is longer than the time from the start of the image data creation process to the start of conveyance in the first control mode. The transfer image or the sheet may be set to be short within a conveyance time range in which the transfer image or the sheet is conveyed between the upstream formation unit and the downstream formation unit.

  In this image forming apparatus, the plurality of image forming units are placed on the upstream side and the downstream side in the transport direction. Therefore, in the second control mode using the downstream image forming unit, the upstream image forming unit is used. Compared to the first control mode, the difference between the sheet conveyance time and the image conveyance time becomes larger. Therefore, in this image forming apparatus, in the second control mode, the time from the start of the image data creation process to the start of sheet conveyance is determined between the upstream forming unit and the downstream forming unit. Since it is set short within the range of the transport time for transport, the processing time in the second control mode can be shortened.

  Further, the image forming apparatus includes a plurality of the supply units, and the control unit forms an image using the first supply unit in which the sheet conveyance time is the first sheet conveyance time in the first control mode. In the second control mode, an image forming process is performed using a second supply unit having a second sheet conveyance time longer than the first sheet conveyance time, and the image data generation process is performed. The time from the start of the sheet to the start of conveyance of the sheet in the second control mode is longer than the time from the start of the image data creation process to the start of conveyance in the first control mode. A configuration may be adopted in which the time is set short within a time difference between the conveyance time and the second sheet conveyance time.

  In this image forming apparatus, since there are a plurality of supply units having different sheet conveyance times, the difference between the sheet conveyance time and the image conveyance time is large in the second supply unit in which the sheet conveyance time is longer than that in the first supply unit. Become. Therefore, in this image forming apparatus, in the second control mode, the time from the start of image data creation processing to the start of sheet conveyance is shortened within the time difference between the first sheet conveyance time and the second sheet conveyance time. Since it is set, the processing time in the second control mode can be shortened.

  In the image forming apparatus, the control unit further executes a prediction process for predicting the creation time of the image data from the creation conditions of the image data, and sets a time for starting conveyance of the sheet from the creation time. It is good also as a structure to determine. The creation time required for creating image data is longer or shorter depending on creation conditions such as the size and resolution of the image data. According to this image forming apparatus, since the creation time is predicted from the creation conditions of the image data, the conveyance of the sheet can be started before the creation time elapses.

  In the image forming apparatus, the image forming unit includes a colorant supply unit that supplies a colorant to the image carrier, and the plurality of colorant supply units corresponding to the plurality of image forming units include: The colorants of different colors may be supplied, and the control unit may perform a monochrome image forming process using the downstream image forming unit in the second control mode. According to this image forming apparatus, processing time can be shortened when performing monochrome image forming processing.

  In the image forming apparatus, the image forming unit includes a colorant supply unit that supplies a colorant to the image carrier, and the plurality of colorant supply units corresponding to the plurality of image forming units include: The colorants of different colors may be supplied, and the control unit may perform a single color image forming process using one of the downstream image forming units in the second control mode. According to this image forming apparatus, the processing time can be shortened when performing a monochromatic image forming process.

  The image forming apparatus disclosed in this specification also includes a reading unit that reads read data from an object to be read, an image forming unit that forms a transfer image using image data created from the read data, and the image The transfer image is formed at an image forming position facing the forming unit, the transfer image is supported, and an image carrier that transports the transfer image to a transfer position different from the image forming position, and the sheet are mounted. A sheet that includes a supply unit, a conveyance unit that conveys the sheet placed on the supply unit to the transfer position, and a control unit, and the conveyance unit conveys the sheet from the supply unit to the transfer position. The conveyance time is longer than the image conveyance time for the image carrier to convey the transferred image from the image forming position to the transfer position, and the control unit generates image data for creating the image data from the read data. A creation process; a prediction process for predicting a creation time required for the image data creation process from the read data; and the conveyance of the sheet is started before the creation of the image data is completed. It is also possible to execute an image forming process in which the image is transferred to the transfer position at the same timing and the transfer image is transferred to the sheet at the transfer position.

  In this image forming apparatus, since the conveyance of the sheet is started before the creation of the image data is completed based on the read data read by the reading unit, the conveyance of the sheet is started after the completion of the creation of the image data. Compared to the technique, the time from creation of image data to the conveyance of the sheet to the transfer position is shortened, and the processing time from creation of image data to transfer of the toner image onto the sheet can be shortened.

  According to the invention disclosed in this specification, it is possible to shorten the processing time from the creation of image data to the transfer of a toner image onto a sheet.

Multi-function machine perspective view Sectional view of the multifunction machine of the first embodiment Block diagram of multifunction device 6 is a flowchart illustrating copy processing of the multifunction machine according to the first embodiment. Time chart in copy processing of multifunction machine of embodiment 1 Sectional view of the multifunction machine of the second embodiment Time chart in copy processing of MFP of embodiment 2 Sectional view of the multifunction machine of the third embodiment 10 is a flowchart illustrating copy processing of the multifunction machine according to the third embodiment. Time chart in copy processing of multifunction machine of embodiment 3

<Embodiment>
An embodiment of the invention disclosed in this specification will be described with reference to FIGS.

1. Configuration of Multifunction Device FIG. 1 is a perspective view showing an appearance of a multifunction device 10 according to the present embodiment. The multifunction machine 10 of the present embodiment includes an apparatus main body 12 and an image reading unit 52 that is arranged on the upper part of the apparatus main body 12 and reads an image from a document. The apparatus main body 12 is used as a sheet material by using image data of a document read by the image reading unit 52 or image data input from the outside of the multifunction machine 10 via an external USB interface (hereinafter referred to as I / F) 54. An image forming unit 30 for forming an image is incorporated. In addition to this, an output unit 72 composed of a liquid crystal display and an input unit 71 composed of a power switch, various setting buttons, and a communication line and receiving an operation command from the user are provided on the front side of the multifunction machine 10. ing. The document is an example of an object to be read, and the multifunction machine 10 is an example of an image forming apparatus.

  FIG. 2 is a side sectional view of the multifunction machine 10. As shown in FIG. 2, the image forming unit 30 is an intermediate transfer type color laser printer that forms a color image using toners of four colors (yellow, magenta, cyan, and black). The toner is an example of a colorant.

  A supply tray 14 is provided on the inner bottom of the apparatus main body 12, and a sheet material 16 such as paper is stacked on the supply tray 14. The supply tray 14 is configured to be openable and closable with respect to the apparatus main body 12. When the sheet material 16 is placed on the supply tray 14 by the user and stored in the apparatus main body 12, the sheet material 16 is pressed against the pickup roller 20 by the pressing plate 18. When the pickup roller 20 rotates, the sheet material 16 is conveyed to the conveyance roller 22 along the conveyance path 28 and is conveyed to the transfer position P <b> 1 in contact with the image forming unit 30. In other words, the pickup roller 20 and the conveyance roller 22 form a conveyance unit 29 that conveys the sheet material 16 placed on the supply tray 14 along the conveyance path 28 to the transfer position P1. The sheet material 16 is an example of a sheet, and the supply tray 14 is an example of a supply unit.

  The image forming unit 30 includes a pair of support rollers 32 and 34, a belt 36, four transfer rollers 37, and an image forming unit 40. The belt 36 is provided between the support rollers 32 and 34 and has a ring shape. The transfer rollers 37 are arranged at equal intervals inside the ring-shaped belt 36. The transfer rollers 37 are arranged at equal intervals inside the ring-shaped belt 36. The support rollers 32 and 34 rotate counterclockwise, and the belt 36 moves accordingly.

  An image forming unit 40 is provided below the belt 36. The image forming unit 40 includes a scanner unit 42 and a process unit 44. The process unit 44 includes four photosensitive drums 48y, 48m, 48c, 48b corresponding to four color toners, four developing cartridges 46y, 46m, 46c, 46b, and the like. In the following description, y, m, c, and b described after the figure numbers indicate that they relate to yellow, magenta, cyan, and black, respectively. Each developing cartridge 46 is filled with toner of each color and is provided with a developing roller 47, and the toner in the developing cartridge 46 is supplied to the corresponding photosensitive drum 48 via the developing roller 47. The belt 36 and the photosensitive drum 48 are an example of an image carrier, the scanner unit 42 is an example of an image forming unit, and the developing cartridge 46 is an example of a colorant supply unit.

  The scanner unit 42 is disposed below each of the four photosensitive drums 48 of the process unit 44. The scanner unit 42 irradiates each photosensitive drum 48 of the process unit 44 with the laser light L at the irradiation position P2 using each color image data created from the image data. As a result, an electrostatic latent image corresponding to an image to be formed on the surface of each photosensitive drum 48 is formed. Then, a developing bias is applied to the developing roller 47 of the developing cartridge 46 from a high voltage power source (not shown), and the toner of the developing cartridge 46 is supplied to the electrostatic latent image, whereby the surface of the photosensitive drum 48 has toner. An image is formed. The irradiation position P2 is an example of an image forming position, and the electrostatic latent image and the toner image are examples of a transfer image.

  When the toner image formed on the surface of the photosensitive drum 48 is carried by the photosensitive drum 48 and passes through the contact position P3 with the belt 36, a transfer bias is applied to the transfer roller 37 from the high voltage power source, and Transferred to the surface. The toner image transferred to the surface of the belt 36 is carried by the belt 36 and conveyed to the transfer position P1 where the support roller 32 and the transfer roller 24 face each other, and the toner image on the belt 36 is transferred to the toner image transfer position. The sheet is transferred to the sheet material 16 conveyed to the transfer position P1 when reaching P1. As a result, an image is formed on the sheet material 16. The image formed on the sheet material 16 is sent to the fixing device 50 to be fixed, and conveyed to a paper discharge tray 38 provided on the upper part of the apparatus main body 12.

  When a color image is formed on the surface of the belt 36 using toner of four colors, it passes through four contact positions P3y, P3m, P3c, and P3b corresponding to the four photosensitive drums 48y, 48m, 48c, and 48b. Each time a toner image of each color is transferred. That is, the yellow toner image of the photosensitive drum 48y placed on the most upstream side at the contact position P3y is first transferred onto the surface of the belt 36, and the magenta toner image and the cyan toner image are transferred onto the yellow toner image. Finally, the black toner image on the photosensitive drum 48b mounted on the most downstream side at the contact position P3b is transferred, and the four color toner images transferred in a superimposed manner are transferred onto the sheet material 16 at once. Therefore, an electrostatic latent image starts to be formed earlier on the photosensitive drum 48y placed on the upstream side than on the photosensitive drum 48b placed on the downstream side.

  In the MFP 10 of the present embodiment, the sheet conveyance time TS for conveying the sheet material 16 from the supply tray 14 to the transfer position P1 is the electrostatic latent image and yellow of the photosensitive drum 48y placed on the most upstream side. The toner image is set to be longer than the image conveyance time TZy for conveying the toner image from the irradiation position P2y to the transfer position P1. For this reason, in the multifunction machine 10, the sheet material 16 starts to be conveyed before the electrostatic latent image starts to be formed. In addition, the time difference ΔTZy between the sheet conveyance time TS and the image conveyance time TZy when the most upstream photosensitive drum 48y is used is equal to the sheet conveyance time TS and the most downstream photosensitive drum 48b. It becomes smaller than the time difference ΔTZb from the image transport time TZb when used.

2. FIG. 3 is a block diagram schematically showing the electrical configuration of the multifunction machine 10. As shown in FIG. 3, the multifunction machine 10 includes an ASIC (application-specific integrated circuit) 60 that controls each unit of the multifunction machine 10. The ASIC 60 includes a CPU 62, a ROM 64, a RAM 66, an image processing circuit 68, and a driving circuit 70, and the image forming unit 30, the image forming unit 40, the conveying unit 29, the image reading unit 52, and the like via a bus 69. It is connected to the USB I / F 54, the input unit 71, the output unit 72, and the like. A range 74 including the CPU 62, the ROM 64, the RAM 66, and the image processing circuit 68 indicated by dotted lines in FIG. 4 is an example of the control unit.

  The ROM 64 stores various programs for controlling the operation of the multifunction machine 10, and the CPU 62 controls each unit according to the program read from the ROM 64. Specifically, the CPU 62 controls the image forming unit 30 and the image forming unit 40 to operate the scanner unit 42 and the developing cartridge 46 so as to form a toner image on the photosensitive drum 48, and the photosensitive drum 48 and the belt 36. Is used to transport the toner image to the transfer position P1.

  The RAM 66 stores image data read by the image reading unit 52 and image data input from outside the multifunction device 10 via the external USB I / F 54. The image processing circuit 68 reads the image data stored in the RAM 66 based on a command from the CPU 62 and converts it into each color image data used in the scanner unit 42.

  The drive circuit 70 is connected to the motor M and transmits a pulse signal to the motor M based on a command from the CPU 62. When the motor M rotates according to the pulse signal input from the drive circuit 70, the transport unit 29 is driven according to the rotation, and the sheet material 16 is transported stepwise along the transport path 28. That is, the CPU 62 transmits a pulse signal to the motor M via the drive circuit 70, and the conveyance unit 29 conveys the sheet material 16 to the transfer position P1 accordingly.

3. Copy Process Next, a copy process of the multifunction machine 10 will be described with reference to FIG. 4 or FIG. FIG. 4 shows a flowchart of a copy process executed by the CPU 62 according to a predetermined program, and FIG. 5 shows a time chart of the copy process. In the present embodiment, a case where copy processing is performed using a standard document such as A4 will be described.

  When the CPU 62 receives a copy command (PL2 in FIG. 5) from the user via the input unit 71, the CPU 62 starts processing, and checks whether the copy instruction is associated with a print mode of color printing or monochrome printing. (S2). Here, color printing means a printing mode using four photosensitive drums 48y, 48m, 48c and 48b corresponding to four color toners, and monochrome printing means only a photosensitive drum 48b corresponding to black toner. It means the printing mode used.

  That is, in color printing, printing processing is performed using the photosensitive drums 48y, 48m, and 48c placed on the upstream side of monochrome printing, and the time difference ΔTZy between the sheet conveyance time TS and the image conveyance time TZy in color printing is obtained. The time difference ΔTZb between the sheet transport time TS and the image transport time TZb in monochrome printing is shorter. In monochrome printing, the printing process is performed without using the photosensitive drums 48y, 48m, and 48c used in color printing, and the printing process is performed using the photosensitive drum 48b placed on the downstream side of the color printing. . Color printing is an example of the first control mode, monochrome printing is an example of the second control mode, the time difference ΔTZy is an example of the first time difference, and the time difference ΔTZb is an example of the second time difference.

  When the received copy command is accompanied by color printing (S2: color printing), the CPU 62 starts reading the document using the image reading unit 52 (S4, FIG. 5PL4) and controls the image processing circuit 68 to read it. Creation of four color image data from the image data is started (S6, FIG. 5PL6).

  Further, the CPU 62 predicts a creation time TM necessary for creating each color image data (S8). The CPU 62 predicts the creation time TM from the creation conditions of each color image data included in the received copy command such as the compression rate and resolution. Then, the CPU 62 starts transporting the sheet material 16 using the transport unit 29 at a timing earlier by the time difference ΔTZy from the predicted creation completion time of each color image data calculated using the creation time TM (S10, FIG. 5PL8). . That is, the CPU 62 starts conveying the sheet material 16 before the creation of each color image data is completed.

  The CPU 62 waits for completion of reading of the original and creation of each color image data after the start of conveyance of the sheet material 16 (S12: NO), and after completion of reading of the original, creation of each color image data is completed. When (S12: YES), color printing processing is executed (S14).

  In the color printing process, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data corresponding to the scanner unit 42y, and starts irradiation of the laser beam L to the photosensitive drum 48y (PL10 in FIG. 5). Further, after the irradiation of the laser beam L to the photosensitive drum 48y is started, the laser beam applied to the photosensitive drum 48m after a time TH1 required for the toner image to be conveyed between the adjacent contact positions P3 by the belt 36. The irradiation of L is started (PL12 in FIG. 5). Thereafter, the CPU 62 similarly starts to irradiate the photosensitive drum 48c and the photosensitive drum 48b with the laser light L (PLs 14 and 16 in FIG. 5).

  As a result, the four color toner images formed by the four photosensitive drums 48y, 48m, 48c, and 48b are transferred to the same portion of the belt 36, and the four color toner images and the sheet material 16 are transferred at the same timing. The four color toner images are transferred to the sheet material 16 at a time at the transfer position P1.

  On the other hand, when the received copy command is accompanied by monochrome printing (S2: monochrome printing), the CPU 62 starts reading the document using the image reading unit 52 (S24, FIG. 5PL4), and controls the image processing circuit 68. Creation of black image data is started from the read image data (S26, FIG. 5PL26). Further, the CPU 62 predicts a creation time TM required for creating black image data (S28). In FIG. 5, for comparison between color printing and monochrome printing, the creation time TM in color printing and the creation time TM in monochrome printing are shown as equal times.

  The CPU 62 starts transporting the sheet material 16 using the transport unit 29 at a timing earlier by the time difference ΔTZb from the predicted creation completion time of each color image data calculated using the creation time TM (S30, FIG. 5PL28). As shown in FIG. 5, the image transport time TZb is only three times the time TH1 than the image transport time TZy, that is, the toner image is transported by the belt 36 from the contact position P3y to the contact position P3m. The time required for is short. Therefore, the CPU 62 starts conveying the sheet material 16 in monochrome printing earlier than the color printing by three times the time TH1.

  The CPU 62 waits for completion of reading of the original and creation of each color image data after the start of conveyance of the sheet material 16 (S32: NO), and after completion of reading of the original, creation of each color image data is completed. When (S32: YES), monochrome printing processing is executed (S34).

  In the monochrome printing process, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data corresponding to the scanner unit 42b, and starts irradiation of the laser light L to the photosensitive drum 48b (PL30 in FIG. 5). As a result, the black toner image formed on the photosensitive drum 48b is transferred to the surface of the belt 36, the black toner image and the sheet material 16 are conveyed to the transfer position P1 at the same timing, and the black toner image is transferred to the sheet material 16 at the transfer position P1. The toner image is transferred.

4). Advantages of the present embodiment (1) In the multi-function device 10 of the present embodiment, the CPU 62 creates each color image data based on the image data read by the image reading unit 52 in both color printing and monochrome printing modes. Since the conveyance of the sheet material 16 is started before the completion, the sheet material 16 is transferred from the start of the creation of each color image data as compared with the conventional technique in which the conveyance of the sheet material 16 is started after the creation of each color image data is completed. It is possible to shorten the time until the sheet is transported to the position P1, and to shorten the processing time required for the copy process.

(2) In the multifunction machine 10 of the present embodiment, the CPU 62 predicts the creation time TM from the creation conditions for each color image data included in the received copy command, such as the compression rate and resolution. Therefore, the creation completion prediction time is calculated from the predicted creation time TM, and the conveyance of the sheet material 16 can be started before the creation completion prediction time, that is, before the creation of each color image data is completed. The necessary processing time can be shortened.

(3) In the multifunction machine 10 of the present embodiment, the CPU 62 starts transporting the sheet material 16 earlier than color printing in monochrome printing in which the time difference ΔTZ between the sheet transport time TS and the image transport time TZ is larger than color printing. Then, the time from the start of creation of each color image data to the start of conveyance of the sheet material 16 is made shorter than that of color printing. Therefore, the processing time required for the copy process in monochrome printing can be shortened.

(4) In the multifunction machine 10 of the present embodiment, the CPU 62 performs sheet processing from the start of creation of each color image data in monochrome printing in which printing processing is performed using the photosensitive drum 48 placed on the downstream side of color printing. 16 is shortened by the time required for the toner image to be transported between the contact position P3y and the contact position P3b by the belt 36, compared with the color printing. Therefore, the processing time required for the copy process in monochrome printing can be shortened.

<Embodiment 2>
A second embodiment will be described with reference to FIG. This embodiment is different from the first embodiment in that the image forming unit 30 is a direct transfer tandem color laser printer that forms a color image using four color toners. In the following description, the same description as that of the first embodiment will not be repeated.

1. Configuration of Multifunction Device In the multi function device 10 of this embodiment, the sheet material 16 placed on the supply tray 14 is conveyed to transfer positions P1y, P1m, P1c, and P1b where the photosensitive drum 48 contacts the corresponding transfer roller 37. Is done. The electrostatic latent image and the toner image formed on each photosensitive drum 48 at the irradiation position P2 are carried by the photosensitive drum 48 and conveyed to the transfer position P1, and when passing through the transfer position P1, each toner image corresponding to each toner image. As the sheet reaches the transfer position P1, it is transferred to the sheet material 16 conveyed to the transfer position P1.

  When a color image is formed on the surface of the sheet material 16 using toner of four colors, it passes through four transfer positions P1y, P1m, P1c, and P1b corresponding to the four photosensitive drums 48y, 48m, 48c, and 48b. Each time a toner image of each color is transferred. That is, on the surface of the sheet material 16, first, the yellow toner image of the photosensitive drum 48y placed on the most upstream side at the transfer position P1y is transferred, then the magenta toner image and the cyan toner image are transferred, and finally transferred. The black toner image on the photosensitive drum 48b placed on the most downstream side at the position P1b is transferred. Therefore, an electrostatic latent image starts to be formed earlier on the photosensitive drum 48y placed on the upstream side than on the photosensitive drum 48b placed on the downstream side.

  In the multifunction machine 10 according to the present embodiment, the sheet transport time TSy in which the sheet material 16 is transported from the supply tray 14 to the transfer position P1y of the photosensitive drum 48y is the transfer position of the electrostatic latent image and the toner image from the irradiation position P2. It is set to be longer than the image transport time TZ transported to P1. For this reason, in the multifunction machine 10, the sheet material 16 starts to be conveyed before the electrostatic latent image starts to be formed. Further, the time difference ΔTSy between the sheet conveyance time TSy to the transfer position P1y corresponding to the photosensitive drum 48y placed on the most upstream side and the image conveyance time TZ corresponds to the photosensitive drum 48b placed on the most downstream side. It becomes smaller than the time difference ΔTSb between the sheet conveyance time TSb to the transfer position P1b and the image conveyance time TZ.

2. Copy Process Next, a copy process of the multifunction machine 10 will be described with reference to FIG. FIG. 7 shows a time chart of copy processing executed by the CPU 62 in accordance with a predetermined program. The multifunction machine 10 according to the present embodiment performs copy processing using a standard document such as A4, and includes two types of printing modes, color printing and monochrome printing.

  In color printing, printing processing is performed using four photosensitive drums 48y, 48m, 48c, and 48b corresponding to toners of four colors. In monochrome printing, the photosensitive drum 48 used in color printing is arranged on the upstream side. The printing process is performed using only the photosensitive drum 48b arranged on the most downstream side, without using the photosensitive drums 48y, 48m, and 48c. Therefore, the time difference ΔTSy between the sheet conveyance time TSy and the image conveyance time TZ in color printing is shorter than the time difference ΔTSb between the sheet conveyance time TSb and the image conveyance time TZ in monochrome printing.

  As shown in FIG. 7, when the received copy command is accompanied by color printing, the CPU 62 conveys the sheet material 16 at a timing earlier by the time difference ΔTSy from the predicted creation completion time of each color image data calculated using the creation time TM. Is started (FIG. 7PL8). Further, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data corresponding to the scanner unit 42y, and starts irradiation of the laser light L to the photosensitive drum 48y (PL10 in FIG. 7).

  Thereafter, the CPU 62 transmits each color image data corresponding to the scanner units 42m, 42c, and 42b every time TH2 required for the sheet material 16 to be conveyed between the adjacent transfer positions P1 by the belt 36. Irradiation of the laser light L to the photosensitive drums 48m, 48c, and 48b is started (PL12, 14, and 16 in FIG. 7). The toner image and the sheet material 16 are conveyed to the corresponding transfer position P1 after the image conveyance time TZ from the transmission of the color image data, and the toner image is transferred to the sheet material 16.

  Further, when the received copy command is accompanied by monochrome printing, the CPU 62 starts conveying the sheet material 16 at a timing earlier by the time difference ΔTSb from the estimated completion time of creation of each color image data (PL28 in FIG. 7). Further, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data corresponding to the scanner unit 42b, and starts irradiation of the laser light L to the photosensitive drum 48b (PL30 in FIG. 7). Then, the black toner image and the sheet material 16 are conveyed to the transfer position P1b after the image conveyance time TZ from the transmission of each color image data, and the black toner image is transferred to the sheet material 16.

  That is, the CPU 62 starts transporting the sheet material 16 before the creation of each color image data is completed in both color printing mode and monochrome printing mode. In monochrome printing, three times as much as time TH2, that is, a time 3 × TH2 required for the sheet material 16 to be conveyed from the transfer position P1y to the transfer position P1b by the belt 36 is faster than color printing. The conveyance of the sheet material 16 is started.

3. Advantages of the present embodiment (1) In the multifunction machine 10 of the present embodiment, the CPU 62 starts transporting the sheet material 16 before the creation of each color image data is completed in both the color printing mode and the monochrome printing mode. Therefore, the processing time required for the copy process can be shortened.

(2) In the multifunction machine 10 of the present embodiment, the CPU 62 performs sheet processing from the start of creation of each color image data in monochrome printing in which printing processing is executed using the photosensitive drum 48 placed on the downstream side of color printing. 16 is shortened by a time required for the sheet material 16 to be transported between the transfer position P1y and the transfer position P1b by the belt 36, compared with the color printing. Therefore, the processing time required for the copy process in monochrome printing can be shortened.

<Embodiment 3>
A third embodiment will be described with reference to FIGS. In the present embodiment, the image forming unit 30 is a direct transfer tandem laser printer that forms a monochrome image using a single color toner, and includes two supply trays, a first supply tray 14A and a second supply tray 14B. 14 is different from the first and second embodiments. In the following description, the same description as in the first and second embodiments will not be repeated.

1. Configuration of MFP In the MFP 10 of the present embodiment, the sheet material 16 placed on each supply tray 14 is conveyed to a transfer position P1 where the photosensitive drum 48 contacts the transfer roller 37. The electrostatic latent image and the toner image formed on the photosensitive drum 48 at the irradiation position P2 are carried by the photosensitive drum 48 and conveyed to the transfer position P1, and when passing through the transfer position P1, the toner image is transferred to the transfer position P1. The sheet is transferred to the sheet material 16 conveyed to the transfer position P1 in accordance with the arrival.

  In the multifunction machine 10 of the present embodiment, the sheet latent time TSA and TSB in which the sheet material 16 is conveyed from the supply trays 14A and 14B to the transfer position P1 of the photosensitive drum 48 are irradiated with the electrostatic latent image and the toner image. The belt 36, the transport path 28, and the transport speeds are set so as to be longer than the image transport time TZ transported from the position P2 to the transfer position P1. For this reason, in the multifunction machine 10, the sheet material 16 starts to be conveyed before the electrostatic latent image starts to be formed. The sheet transport time TSB transported from the supply tray 14B to the transfer position P1 is set longer than the sheet transport time TSA transported from the supply tray 14A to the transfer position P1, and therefore, the sheet transport time TSB and the image A time difference ΔTSB from the conveyance time TZ is larger than a time difference ΔTSA between the sheet conveyance time TSA and the image conveyance time TZ.

2. Copy Process Next, a copy process of the multifunction machine 10 will be described with reference to FIG. 9 or FIG. FIG. 9 shows a flowchart of a copy process executed by the CPU 62 in accordance with a predetermined program, and FIG. 10 shows a time chart of the copy process. In the present embodiment, a case where copy processing is performed using a standard document such as A4 will be described.

  When the CPU 62 receives a copy command (PL2 in FIG. 10) from the user via the input unit 71, the CPU 62 starts the process, and confirms from which supply tray 14 the print mode with paper feed is included (see FIG. 10). S42). The print mode using the supply tray 14A is an example of a first control mode, and the print mode using the supply tray 14B is an example of a second control mode. In addition, the time difference ΔTSA between the sheet conveyance time TSA and the image conveyance time TZ in the printing mode using the supply tray 14A is an example of the first time difference, and the sheet conveyance time TSB and the image conveyance in the printing mode using the supply tray 14B. A time difference ΔTSB from the time TZ is an example of a second time difference.

  When the received copy command is accompanied by paper feeding from the supply tray 14A (S42: supply tray 14A), the CPU 62 starts reading the document using the image reading unit 52 (S44, FIG. 10PL4), and the image processing circuit 68. Then, the creation of each color image data is started from the image data read by controlling (S46, FIG. 10PL6).

  Further, the CPU 62 predicts a creation time TM necessary for creating each color image data (S48). Then, the CPU 62 starts transporting the sheet material 16 at a timing earlier by the time difference ΔTSA than the predicted creation completion time of each color image data calculated using the creation time TM (S50, FIG. 10PL8). That is, the CPU 62 starts conveying the sheet material 16 before the creation of each color image data is completed.

  The CPU 62 waits for the completion of reading of the original and creation of each color image data after the start of conveyance of the sheet material 16 (S52: NO), and after completion of the reading of the original, the creation of each color image data is completed. If (S52: YES), the printing process is executed (S54). In the printing process, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data to the scanner unit 42, and starts irradiation of the laser light L to the photosensitive drum 48 (PL10 in FIG. 10). The toner image and the sheet material 16 are conveyed to the transfer position P1 after the image conveyance time TZ from the transmission of the color image data, and the toner image is transferred to the sheet material 16.

  On the other hand, when the received copy command is accompanied by paper feeding from the supply tray 14B (S42: supply tray 14B), the CPU 62 starts reading the document using the image reading unit 52 (S64, FIG. 10PL4), and performs image processing. Creation of each color image data is started from the image data read by controlling the circuit 68 (S66, FIG. 10PL26).

  Further, the CPU 62 predicts a creation time TM required for creating each color image data (S68). Then, the CPU 62 starts conveying the sheet material 16 at a timing earlier than the supply tray 14B by a time difference ΔTSB from the predicted completion time of creation of each color image data calculated using the creation time TM (S70, FIG. 10PL28). That is, the CPU 62 starts transporting the sheet material 16 when feeding from the supply tray 14B is earlier than when feeding from the supply tray 14A.

  The CPU 62 waits for completion of reading of the original and creation of each color image data after the start of conveyance of the sheet material 16 (S72: NO), and after completion of reading of the original, creation of each color image data is completed. If (S72: YES), the printing process is executed (S74). In the printing process, immediately after the creation of each color image data is completed, the CPU 62 transmits each color image data to the scanner unit 42, and starts irradiation of the laser light L to the photosensitive drum 48 (PL30 in FIG. 10). The toner image and the sheet material 16 are conveyed to the transfer position P1 after the image conveyance time TZ from the transmission of the color image data, and the toner image is transferred to the sheet material 16.

3. Advantages of the present embodiment (1) In the multifunction machine 10 of the present embodiment, the CPU 62 allows the sheet material 16 to be printed before the creation of each color image data is completed in any print mode involving paper feed from any supply tray 14. Since the conveyance is started, the processing time required for the copy process can be shortened.

(2) In the multifunction machine 10 according to the present embodiment, the CPU 62 starts the sheet generation from the start of the creation of each color image data in the printing mode that involves feeding from the supply tray 14B, which takes longer time to transport the sheet material 16 than the supply tray 14A. The time until the conveyance of the material 16 is started is made shorter by the difference time ΔTS between the conveyance times TSA and TSB than in the print mode with paper feeding from the supply tray 14A. Therefore, it is possible to reduce the processing time required for the copy process in the print mode that involves feeding from the supply tray 14B.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.
(1) Although the above embodiment has been described using the multifunction machine 10 having the scanner function and the print function as the image forming apparatus, the present invention is not limited to this. For example, if the printer may have only a print function, the multifunction machine 10 may further include a function such as a facsimile function. When the image forming apparatus is a printer, the image processing circuit 68 creates each color image data from the image data stored in the RAM 66 in advance.

(2) In the above-described embodiment, the image reading unit 52 has been described using an example in which a copy process is performed using a standard document such as A4. However, the present invention is not limited to this. If the original is not a fixed form, for example, the image reading unit 52 is a flatbed method, and if the original can be grasped before it is read by pre-scanning or the like, the original is created based on the grasped original. The time TM may be predicted. Further, when the image reading unit 52 is an auto document feeder system and the size of the original cannot be grasped before the original is read, the creation time is calculated from the time required for reading the original or the conveyance time required for reading the original. TM may be predicted.

(3) In the above embodiment, the description has been given using the example in which the control unit is the range 74 including the CPU 62, the ROM 64, and the like. However, the control unit is dedicated to executing different CPUs, ASICs, and various processes. You may comprise using an apparatus etc.

(4) Further, the program executed by the CPU 62 does not necessarily have to be stored in the ROM 64, and may be stored in the CPU 62 itself or in another storage device.

(5) Although the above embodiment has been described using an example in which only the photosensitive drum 48b corresponding to the black toner placed on the most downstream side is used as monochrome printing, the present invention is not limited to this. For example, monochrome printing may be performed using only one of the photosensitive drums 48m and 48c other than the photosensitive drum 48b corresponding to the yellow toner placed on the most upstream side. Alternatively, the photosensitive drum 48b may be disposed on the most upstream side, and monochrome printing may be performed using a plurality of the photosensitive drums 48y, 48m, and 48c disposed on the downstream side.

(6) The above embodiment has been described using an example in which the process for predicting the creation time TM is performed in the copy process. However, when the creation time TM is calculated and stored in advance based on the creation conditions. There is no need to predict the creation time TM again.

(7) In the above embodiment, the description has been given using an example in which each color image data is transmitted to the scanner unit 42 after the creation of each color image data is completed and the irradiation of the laser beam L to the photosensitive drum 48 is started. The invention is not limited to this. For example, each color image data may be transmitted to the scanner unit 42 every time completion of creation of each color image data is completed at a predetermined rate, and irradiation of the laser light L to the photosensitive drum 48 may be started. In this case, conveyance of the sheet material 16 is started earlier by the time difference ΔTZ (ΔTS) than the timing at which each color image data is transmitted to the scanner unit 42 earliest.

(8) In the embodiment described above, the sheet conveyance time TS is set to be longer than the image conveyance time TZy, but may be set to be the same. In that case, the sheet material 16 may not be conveyed from the supply tray 14 but may be conveyed from the conveyance roller after a predetermined conveyance roller of the conveyance unit 29 sandwiches the sheet material 16.

(9) In the above-described embodiment, in monochrome printing, the time from the start of the creation of each color image data to the start of conveyance of the sheet material 16 is determined from the contact position P3y to the contact position P3b by the belt 36 rather than the color printing. Although it has been described that the time required to be conveyed between the contact positions P3y and the contact position P3b is shortened, it may be shortened within a range of time required to be conveyed. In this case, the timing for starting the irradiation of the laser beam L to the photosensitive drum 48b is adjusted using the timing for starting the conveyance of the sheet material 16.

10: MFP, 14: supply tray, 24: transfer roller, 29: transport unit, 30: image forming unit, 37: transfer roller, 42: scanner unit, 46: developing cartridge, 48: photosensitive drum, 52: image reading 68, image processing circuit, 70: drive circuit, P1: transfer position, P2: irradiation position, P3: contact position, TM: creation time, TS: sheet conveyance time, TZ: image conveyance time, ΔTS, ΔTZ: Time lag

Claims (8)

An image forming unit that forms a transfer image using image data;
An image carrier that forms the transfer image at an image forming position facing the image forming unit, carries the transfer image, and conveys the transfer image to a transfer position different from the image forming position;
A supply unit on which the sheet is placed;
A transport unit that transports the sheet placed on the supply unit to the transfer position;
A control unit;
With
The sheet conveyance time for the conveyance unit to convey the sheet from the supply unit to the transfer position is longer than the image conveyance time for the image carrier to convey the transfer image from the image forming position to the transfer position.
The controller is
Image data creation processing for creating the image data;
An image in which the conveyance of the sheet is started before the creation of the image data is completed, the sheet and the transfer image reach the transfer position at the same timing, and the transfer image is transferred to the sheet at the transfer position. An image forming apparatus that executes a forming process. The image forming apparatus according to claim 1,
There are a plurality of at least one of the image forming unit and the supply unit,
The controller is
A first control mode for performing an image forming process using a combination of the supply unit and the image forming unit in which a difference between the sheet conveying time and the image conveying time is a first time difference;
The difference between the sheet conveyance time and the image conveyance time is not the combination of the supply unit and the image forming unit where the difference between the sheet conveyance time and the image conveyance time is the first time difference, and the difference between the sheet conveyance time and the image conveyance time is the first time difference. A second control mode for performing an image forming process using a combination of the supply unit and the image forming unit that have a second time difference greater than
The time from the start of the image data creation process to the start of sheet conveyance in the second control mode is the time from the start of the image data creation process to the start of sheet conveyance in the first control mode. Shorter than the image forming apparatus. The image forming apparatus according to claim 2,
A plurality of the image forming units;
The controller is
In the first control mode, an image forming process is performed using the upstream image forming unit placed on the upstream side in the transport direction of the transfer image or the sheet,
In the second control mode, an image forming process is performed using the downstream image forming unit placed on the downstream side of the plurality of image forming units,
The time from the start of the image data creation process to the start of conveyance of the sheet in the second control mode is longer than the time from the start of the image data creation process to the start of conveyance in the first control mode. The image forming apparatus, wherein the transfer image or the sheet is set to be short within a conveyance time in which the transfer image or the sheet is conveyed between the upstream formation unit and the downstream formation unit. The image forming apparatus according to claim 2,
Comprising a plurality of the supply sections;
The controller is
In the first control mode, an image forming process is performed using the first supply unit in which the sheet conveyance time is the first sheet conveyance time.
In the second control mode, an image forming process is performed using a second supply unit in which the sheet conveyance time is a second sheet conveyance time longer than the first sheet conveyance time,
The time from the start of the image data creation process to the start of conveyance of the sheet in the second control mode is longer than the time from the start of the image data creation process to the start of conveyance in the first control mode. The image forming apparatus is set short within a time difference between the first sheet conveyance time and the second sheet conveyance time. An image forming apparatus according to any one of claims 1 to 4,
The controller is
Further executing a prediction process for predicting the creation time of the image data from the creation conditions of the image data,
An image forming apparatus that determines a time to start conveying the sheet from the creation time. The image forming apparatus according to claim 3, wherein
The image forming unit includes a colorant supply unit that supplies a colorant to the image carrier,
The plurality of colorant supply units corresponding to the plurality of image forming units supply the colorants of different colors, respectively.
The image forming apparatus, wherein the control unit performs a monochrome image forming process using the downstream image forming unit in the second control mode. The image forming apparatus according to claim 3, wherein
The image forming unit includes a colorant supply unit that supplies a colorant to the image carrier,
The plurality of colorant supply units corresponding to the plurality of image forming units supply the colorants of different colors, respectively.
In the second control mode, the control unit performs a monochrome image forming process using one of the downstream image forming units. A reading unit for reading the read data from the reading object;
An image forming unit that forms a transfer image using image data created from the read data;
An image carrier that forms the transfer image at an image forming position facing the image forming unit, carries the transfer image, and conveys the transfer image to a transfer position different from the image forming position;
A supply unit on which the sheet is placed;
A transport unit that transports the sheet placed on the supply unit to the transfer position;
A control unit;
With
The sheet conveyance time for the conveyance unit to convey the sheet from the supply unit to the transfer position is longer than the image conveyance time for the image carrier to convey the transfer image from the image forming position to the transfer position.
The controller is
Image data creation processing for creating the image data from the read data;
A prediction process for predicting a creation time required for the image data creation process from the read data;
An image in which the conveyance of the sheet is started before the creation of the image data is completed, the sheet and the transfer image reach the transfer position at the same timing, and the transfer image is transferred to the sheet at the transfer position. An image forming apparatus that executes a forming process.

Images