JP5216297B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that performs duplex printing based on print data transmitted from an external device such as a personal computer.

As a prior art related to this type of image forming apparatus, there is one that employs a sequence in which a sheet is fed one side at a time (first sheet feeding and second sheet feeding) and printing is performed on both sides (for example, Patent Document 1). reference.). In this prior art, when the number of copies to be printed is less than a predetermined number of copies and the total number of pages in the job is an odd number, the final sheet is fed by the first feed by the printer controller. Is then fed by the second paper feed and the second side of the paper is printed based on the white page data.
JP-A-8-262814 (FIG. 1)

  However, when performing double-sided printing sequence processing as in the prior art, the printing paper is discharged from the apparatus through the transport path in the order of the double-sided printing unit and the discharge tray from the state accommodated in the paper feed cassette. This transport path is no exception even when the printing surface is only one side. In the above prior art, a transport path is used in which the first side is printed by the first paper feed and then the second side is left blank by the second paper feed.

  As an example in which the printing surface is only one side in the double-sided printing sequence, there is a case where one page is printed by specifying both sides, or the last page when the total number of pages is an odd number. In this way, even when the printing surface is only one side, the printing paper passes through the same conveyance path as in the case of both sides, but the printing paper is wastedly conveyed in the duplex printing unit even though printing is not performed again. Pass will be carried. As a result, there is a problem that it takes time until the sheet is discharged outside the apparatus, and the entire printing time becomes long.

  Actually, in the printing apparatus of the prior art (Patent Document 1), when the double-sided printing sequence is selected, the first side of the final paper is first printed, and then the second side of the paper is continuously printed based on the white page data (however, the image Is no transfer). During this time, the printing paper is conveyed via the switching mechanism, the transfer unit, the fixing unit, etc. to print the second surface, and as a result, the time until the printing paper is discharged outside the apparatus is wasted. There is a problem that is getting longer.

  Further, when the printing paper is transported through a waste transport path in the double-sided printing unit or the transfer unit as described above, there is a problem that a risk of causing a path error or a paper jam (JAM) increases in the process.

  Therefore, an object of the present invention is to provide an image forming apparatus capable of performing duplex printing more efficiently when the total number of pages is an odd number.

  In the image forming apparatus of the present invention, when print data transmitted in units of jobs is received, an image is formed based on the received print data. At this time, if double-sided printing is specified in the job, after the sheet is conveyed in a mode in which one side is opposed to the image forming unit, the sheet is reversed so that the opposite side is opposed to the image forming unit. Transport the paper. This is a transport path (first transport means) for duplex printing, and in this case, normal duplex printing is performed. On the other hand, when double-sided printing is not specified in the job, the sheet is conveyed in such a manner that only one side is opposed to the image forming unit. This is a single-sided printing conveyance path (second conveying means). In this case, single-sided printing is executed.

  In addition, when the print data of the job for which duplex printing is specified and the total number of pages is an odd number, the image forming apparatus of the present invention starts to measure the elapsed time when the last page of print data is received. To do. If print data of a job that newly designates double-sided printing is received before the predetermined time is measured, double-sided printing is continued using the conveyance path for double-sided printing, while new double-sided printing is performed. When the predetermined time is measured without receiving the print data of the designated job, printing is performed by switching the transport path.

  As a result, the paper of the last page is printed through the conveyance path for single-sided printing without passing through the conveyance path for double-sided printing. Therefore, it is possible to prevent the paper of the last page from being conveyed via a useless conveyance path. In addition, since the paper is printed on only one side of the last page and then discharged to the discharge tray as it is, the time required until all the paper is finally discharged is shortened. Printing time can be shortened.

  According to the present invention, it is possible to store at least one of the printing conditions obtained from the print data and the model information related to the model, and to reduce the printing time by actually switching the transport path based on the stored information. Judge whether or not. As a result, conveyance path switching control can be executed only when it is determined that the printing time can be shortened.

  According to the image forming apparatus of the present invention, it is possible to perform the duplex printing more efficiently when the total number of pages is an odd number.

Hereinafter, embodiments of the image forming apparatus of the present invention will be described.
FIG. 1 is a vertical sectional front view schematically showing an image forming apparatus 1 of the present embodiment. A solid line arrow in the figure indicates a sheet conveyance path and its conveyance direction.

  As shown in FIG. 1, the image forming apparatus 1 includes a cassette type paper feeding unit 3 at the bottom of a main body 2, a manual paper feeding unit 5 that protrudes to the right above the right side, and a document feeding unit at the top. 8. Optical parts 9 are respectively arranged at positions above the main body 2 below the document feeding part 8. In addition, a paper transport unit 6 is provided inside the main body 2.

  The cassette type paper feed unit 3 is provided with three stages of paper feed cassettes 4. The paper feed cassette 4 is a so-called front loading type, and each of the paper feed cassettes 4 can slide out from the main body 2 to the front side (front side as viewed in FIG. 1). In each paper feed cassette 4, paper P such as cut paper before printing is stacked and accommodated. From the cassette type paper feed unit 3, the paper P stacked in the paper feed cassette 4 is separated and sent out one by one.

  Different paper sizes and paper types can be set in the upper, middle, and lower paper feed cassettes 4 at respective positions. For example, the uppermost sheet feeding cassette 4 is used for multipurpose purposes, and can accommodate OHP sheets, thick paper, thin paper, and the like. The middle sheet cassette 4 can store A4 plain paper, which is relatively frequently used, and the bottom sheet cassette 4 can store sheets larger than A4. The paper size, paper type, and the like stored in the paper cassette 4 at each stage can be set in the image forming apparatus 1 in advance.

  On the manual sheet feeding unit 5, paper P having a size that is not in the cassette type sheet feeding unit 3 or a sheet to be fed one by one such as an OHP sheet is placed. The manual sheet feeding unit 5 may be configured to be folded and stored on the right side surface of the main body 2.

  The paper transport unit 6 is positioned to the right of the paper feed direction when viewed from the relationship with the cassette type paper feed unit 3, and is positioned to the left when viewed from the relationship with the manual paper feed unit 5. The paper P sent out from the cassette type paper feed unit 3 is transported vertically upward along the side surface of the main body 2 by the paper transport unit 6, and the paper P sent out from the manual paper feed unit 5 is transported horizontally. Each reaches the transfer section 11.

  The document feeder 8 is used when a user copies and prints a document. When the user copies an original, an original on which an image such as a character, a figure, or a pattern is drawn is loaded on the original feeding unit 8. When there are a plurality of documents, the document feeding unit 8 separates and transports the documents one by one, and the optical unit 9 reads the image.

  The image forming apparatus 1 also has a function as a network printer or a network scanner, and can receive print data transmitted from, for example, a personal computer (client terminal) (not shown) by an interface unit. The configuration of the interface unit and the like will be described later.

  In the main body 2, a print engine 10 and a transfer unit 11 serving as an image forming unit are provided in a downstream position when viewed in the paper conveyance direction from the paper conveyance unit 6. Among these, the print engine 10 forms an electrostatic latent image of the original image based on the read image or image data obtained by processing the print data received from the client terminal, and further forms a toner image from the electrostatic latent image. The

  A registration roller 7 is provided on the downstream side in the paper transport direction from the paper transport unit 6 and immediately upstream of the transfer unit 11. The registration roller 7 corrects the oblique feeding of the paper P and sends the paper P toward the transfer unit 11 while synchronizing with the toner image formed by the print engine 10. In the transfer unit 11, the toner image is transferred with either one of the front and back surfaces of the paper P sent while being synchronized by the registration roller 7 as the front printing surface.

  A fixing unit 12 is provided on the downstream side of the transfer unit 11 when viewed in the paper transport direction. The paper P carrying the unfixed toner image in the transfer unit 11 is sent to the fixing unit 12 where it is heated and pressurized to fix the toner image.

  In addition, a discharge / branching unit 13 is provided on the downstream side of the fixing unit 12 in the sheet conveyance direction and in the vicinity of the left side surface of the main body 2. When duplex printing is not performed (single-sided printing), the paper P discharged from the fixing unit 12 is discharged from the discharge / branch unit 13 to the discharge tray 14 as it is. In this way, the paper P is discharged from the fixing unit 12 to the outside of the apparatus via the transport path B via the discharge / branch unit 13 and the discharge tray 14.

  A duplex printing unit 20 is provided below the portion from the print engine 10 to the discharge / branch unit 13 and above the cassette type paper feed unit 3. When duplex printing is performed, the paper P discharged from the fixing unit 12 is sent to the duplex printing unit 20 through the discharge / branch unit 13. The transport direction of the paper P sent to the duplex printing unit 20 is subsequently switched by the paper reversing device 30 provided in the duplex printing unit 20, and from here through the paper transport unit 6 and the registration roller 7 again. It is sent to the transfer unit 11.

  The sheet reversing device 30 includes a switchback mechanism 60 and a shift mechanism 70. The switchback mechanism 60 is for reversing the transport direction of the paper P. The shift mechanism 70 is for correcting a positional deviation in the width direction of the paper. A sensor 31 for detecting a positional shift of the paper P in the width direction is provided upstream of the shift mechanism 70 in the paper transport direction.

  The intermediate tray 21 is installed on the further downstream side of the switchback mechanism 60 when viewed in the direction of entry into the sheet reversing device 30. The intermediate tray 21 temporarily stores the paper P printed on one side. The switchback mechanism 60 temporarily stores the paper P in the intermediate tray 21 and then switches it back to switch the transport direction.

  The position of the paper P that has been switched back is corrected by the shift mechanism 70 and then reversed so as to sink downward at a position downstream of the transport direction. The paper P is fed to the right by the plurality of transport rollers 53 below the transfer unit 11 and the print engine 10, and then joins the paper transport unit 6 while rising slightly obliquely.

  In this way, when the paper P is sent again to the transport unit 6 via the transport path A via the discharge / branch unit 13, the switchback mechanism 60, the intermediate tray 21, the shift mechanism 70, and the transport roller 53, it is printed first. The front print surface is turned downward and sent to the print engine 10, and double-sided printing is performed with the other surface, that is, the back surface of the front print surface as the rear print surface. The paper P on which double-sided printing has been performed is discharged to the discharge tray 14 through the discharge / branching unit 13. Alternatively, the paper P is reversed again by the paper reversing device 30 and then conveyed upward along the left side portion of the main body 2 and discharged to the discharge tray 14 (face down).

  In the image forming apparatus 1 of the present embodiment, two types of modes, a normal duplex printing mode and a high-speed duplex printing mode, are prepared when performing duplex printing. Among these, in the normal duplex printing mode, the conveyance direction is switched by the sheet reversing device 30 one by one with respect to the sheet P, and then the sheet is sent again to the transfer unit 11 to perform duplex printing. In the normal duplex printing mode, after duplex printing of one sheet in this way, the next sheet is sequentially duplex printed.

  On the other hand, the high-speed double-sided printing mode is a mode in which double-sided printing is performed on the paper P in parallel by a predetermined number. In this mode, operations such as the transfer of the toner image onto the paper P in the transfer unit 11, the storage of another paper P in the intermediate tray 21, and the transport of another paper P by the transport roller 53 are performed in parallel. Thus, double-sided printing of a predetermined number of sheets P is performed in parallel, and the printing process proceeds at a higher speed than in the normal double-sided printing mode. These two types of modes can be switched according to printing conditions and image data capacity.

  FIG. 2 is a block diagram schematically showing the control configuration of the image forming apparatus 1. The image forming apparatus 1 includes a control unit 100 for controlling the operation. The control unit 100 is configured by an electronic circuit including a central processing unit (CPU), for example, and is built in the image forming apparatus 1 in a state where the electronic circuit is formed on a circuit board.

  The above-described document feeding operation by the document feeding unit 8, the image reading operation by the optical unit 9, the sheet feeding operation from the cassette type sheet feeding unit 3, and the like are controlled by the control unit 100. The operation of the image forming by the print engine 10 and the transfer unit 11, the fixing unit 12, the discharge / branch unit 13, and the duplex printing unit 20 are all controlled by the control unit 100.

  Further, a timer 101, an operation / display unit 102, a transport path switching unit 103, a storage unit 104, and an interface unit 105 are connected to the control unit 100 as other components. Of these, although not shown in FIG. 1, the operation / display unit 102 is provided, for example, on the upper surface of the main body 2 at a position on the front side of the document feeding unit 8 as viewed from the user. The operation / display unit 102 has a touch-type panel in addition to the operation keys, and can accept a user's touch operation through the display screen in addition to operations on the operation keys. The storage unit 104 includes, for example, a storage device (ROM, RAM), a large-capacity storage device (hard disk), and the image read by the optical unit 9 is temporarily stored in the storage unit 104 in a predetermined data format. Memorized.

  In the image forming apparatus 1, for example, data set through operation of the operation / display unit 102 for each job or data set by a job received from an external personal computer is stored in the storage unit 104 via the control unit 100. The This setting includes paper size, type and feeding direction, double-sided or single-sided printing format, document density, frame erasing, binding margin, 4-in-1 aggregation processing, and the like, and the control unit 100 performs image processing according to each setting. Is done. The time required for the image processing by the control unit 100 depends on the contents of this setting. The storage unit 104 stores, for example, a multi-function application program that performs multi-thread processing.

  For example, in image processing that involves copying a document, when a user presses a start button (not shown) of the operation / display unit 102 with the document placed on the document feeder 8, the following operations are performed according to this operation. Is performed. First, when a paper sensor (not shown) built in the document feeding unit 8 detects a document sheet, the document feeding unit 8 feeds the document one by one, and the optical unit 9 in the middle of the document image Are scanned. The image data read at this time is stored in the storage unit 104 via the control unit 100 in units of one job.

  The storage unit 104 stores model information of the image forming apparatus 1 (codes such as “PR-1234” and “LP-C2007”) and configuration information of the image forming apparatus 1. The configuration information includes information on the transport distances of the transport path A and the transport path B obtained from the structural dimensions of the duplex printing unit 20, the discharge / branch unit 13, and the paper transport unit 6 in the image forming apparatus 1. ing.

  The timer 101 measures a set time (for example, several seconds to several tens of seconds) preset in the image forming apparatus 1. Specifically, the measurement is started from the timing when the print data of the last page for double-sided printing in which the total number of pages transmitted from the client terminal is an odd number is received. The set time includes, for example, the time between timings after the transfer to the front print surface of the paper P and the transfer of the toner image to the subsequent print surface when performing double-sided printing. Details of the control will be described later using another flowchart.

  In addition, when printing on only one side of the paper P even if duplex printing is specified, the transport path switching unit 103 transports the path through which the paper P is transported from the transport path A under the control of the control unit 100. It has a function of switching the discharge / branching unit 13 so as to change to the path B. When the transport path switching unit 103 switches to the transport path B, the paper P is discharged to the outside of the apparatus via the discharge / branch unit 13 and the discharge tray 14 without passing through the duplex printing unit 20.

  Here, when duplex printing is designated and printing is performed only on one side of the paper P, only the last page for duplex printing in which the total number of pages is an odd number, or only one page for which duplex printing is designated. Printing etc. are mentioned.

  The interface unit 105 has a function of receiving print data via a network using a cable connected to a connection terminal provided in a part of the image forming apparatus 1. The interface unit 105 receives print data transmitted via a network from a client terminal operated by a user.

  When the interface unit 105 receives print data transmitted from the client terminal, the control unit 100 analyzes the print data and extracts print conditions. Then, the control unit 100 stores the printing condition in the storage unit 104. The printing conditions include conditions and settings related to printing such as designation of double-sided printing, the size of the paper P, and face-up / face-down (FU / FD).

  When the control unit 100 processes print data received from an external client terminal to generate image data, the control unit 100 supplies the image data to the print engine 10. Further, the control unit 100 performs preprocessing such as image noise removal on the image data read by the optical unit 9, and further performs image processing according to various settings, and the data is printed for each page. 10 is supplied. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum of the print engine 10, and this is developed with toner.

  On the other hand, inside the image forming apparatus 1, the paper taken out from the cassette type paper feeding unit 3 is sent to the registration roller 7 and is temporarily stopped here. When the photosensitive drum of the print engine 10 reaches a predetermined rotation angle, the sheet is transported again by the registration roller 7 at this timing, whereby the toner image is transferred onto the sheet.

  When double-sided printing is set (specified) in the current job, the paper on which the toner image is transferred is heated and pressurized through the fixing unit 12, and then the conveyance direction is downward in the discharge / branch unit 13. And is sent out toward the duplex printing unit 20.

  The basic configuration and operation of the image forming apparatus 1 have been described above. In addition, in the present embodiment, for example, when double-sided printing is designated by print data transmitted from a client terminal, one side of the paper P In the process when printing only, it has the following characteristics.

  FIG. 3 is a flowchart of double-sided printing control processing by the control unit 100. Hereinafter, it demonstrates along each procedure.

  As a premise of duplex printing, for example, print data for duplex printing of a document or an image is created at a client terminal. At this time, it is assumed that the print data has a total number of 1 or an odd number such as 3, 5, 7,. When the user designates double-sided printing and gives a print instruction, the client terminal sequentially transmits the print data of the print job for which the print instruction is given via the network.

The control unit 100 sequentially receives print data for each sheet via the interface unit 105, and performs double-sided printing based on each print data.
Step S301: Eventually, the control unit 100 receives the print data of the last page. At this time, the duplex printing is executed in the high-speed duplex printing mode. When the print data designating double-sided printing is only one page, the control unit 100 receives the print data of only one page as the last page. Note that the double-sided printing is designated by only one-page document, for example, if the printer driver configuration is a standard two-sided printing, if the user is dare to specify the format of the two-sided printing.

  Step S302: Next, the control unit 100 starts the timer 101 and starts measuring the set time at the timing when the print data of the last page is received.

  Step S303: The control unit 100 analyzes the print data transmitted from the client terminal in step S301, and extracts printing conditions including designation of double-sided printing and the size of the paper P. Then, the control unit 100 causes the storage unit 104 to store the extracted printing conditions.

  Step S304: While measuring the set time by the timer 101, the control unit 100 determines whether or not the next double-sided print data, that is, the print data of a new print job has been received from the client terminal. .

  Step S305: As a result, when the print data for the next double-sided printing is not received within the set time (step S304: NO), the control unit 100 stores the printing conditions and model stored in the storage unit 104 in step S303. Read information and configuration information. Further, based on the read information, the transport distance of transport path A and transport path B and the time required for transporting paper P in transport path A and transport path B are calculated, and these calculated times are calculated. Is performed, and it is determined whether or not the printing time can be shortened when the transport path A is switched to the transport path B in printing the last page.

  Step S306: When it is determined that the printing time can be shortened (step S305: YES), the control unit 100 controls the conveyance path switching unit 103 to change the conveyance path of the paper P when printing the final page. The conveyance path A is switched to the conveyance path B.

  Step S307: The control unit 100 causes the last page to be printed. At this time, if the transport path of the paper P is switched from the transport path A to the transport path B in step S306, the paper P is passed through the duplex printing unit 20 after the toner image is fixed by the fixing unit 12. Instead, it is discharged to the outside of the apparatus via the discharge / branch portion 13 and the discharge tray 14 as it is.

  On the other hand, when the print data for the next double-sided printing is received within the set time in step S304 (step S304: YES), or when it is determined in step S306 that the printing time can be shortened (step S305: NO), the control unit 100 does not switch from the transport path A to the transport path B by the transport path switching unit 103, and prints the next print data as usual in the high-speed duplex printing mode.

  In this way, when it is determined that the switching of the transport path is appropriate in printing on the final page for double-sided printing in which the total number of pages is an odd number, the paper is discharged without passing through the double-sided printing unit 20. By switching the transport path in this way, it is possible to prevent a useless transport path from being routed. In this case, since the paper P is directly discharged from the discharge tray 14 after printing, the total printing time is shortened accordingly, and the job can be completed more efficiently.

  In the above-described embodiment, it is assumed that plain paper is used as the paper type. However, the paper type is, for example, punched paper (Prepunched), printed paper (Preprinted), letterhead (Letterhead), or the like. In this case, the above control may basically be canceled.

1 is a vertical sectional front view schematically showing a configuration of an image forming apparatus. 2 is a block diagram illustrating a control configuration of the image forming apparatus. FIG. 3 is a flowchart illustrating an operation of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 10 Print engine 11 Transfer part 12 Fixing part 13 Discharge / branch part 20 Duplex printing unit 100 Control part 101 Timer 103 Conveyance path switching part 105 Interface part

Claims (1)

Receiving means for receiving print data transmitted in units of jobs;
An image forming unit that forms an image based on print data received by the receiving unit;
When duplex printing is specified in the job, the sheet is conveyed in such a manner that one side is opposed to the image forming unit, and then the sheet is reversed so that the opposite side is opposed to the image forming unit. First conveying means for conveying
When duplex printing is not designated in the job, a second conveying unit that conveys the sheet in a mode in which only one side is opposed to the image forming unit;
Printing execution means for executing printing by transferring the image formed by the image forming unit to the paper conveyed by the first or second conveying means;
For print data of a job for which double-sided printing is specified, when the print data of the last page is received when the total number of pages is an odd number, a measurement unit that starts a predetermined timer and starts measuring time;
Storage means for storing at least one of printing conditions obtained from the print data received by the receiving means and model information about the model;
If the receiving unit receives print data of a job that newly designates double-sided printing until the predetermined time is measured by the measuring unit, the first conveying unit continuously conveys the paper and performs the printing. When the execution unit causes double-sided printing to be executed, while the receiving unit does not receive print data of a job that newly designates double-sided printing, and the measurement unit measures a predetermined time, the printing stored in the storage unit Based on the conditions and the model information , it is determined whether or not the printing time of the last page can be shortened by switching the printing of the last page from the first conveying unit to the second conveying unit. further comprising a switching means for transporting the sheet of the last page from the first conveying means when it is determined that can be shortened by switching to the second conveying means An image forming apparatus comprising.

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