JP2007149035A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, of which usability is enhanced by preventing wasteful white paper discharge when a user cancels a print job while no print job is started for a long period with papers being provided and the wastful white paper is likely to be discharged. <P>SOLUTION: The apparatus compares time for finishing a print job for a previous-page with time for developing an image for the next page when two or more pages are continuously printed. When the image is developed earlier, a paper sheet for the next page is fed in advance so that the printing speed is increased. When the job completes earlier, the next paper sheet is not fed in advance so that a white paper sheet is not discharged. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, for example, an image forming apparatus that develops information transferred by a host computer through an interface circuit into image information, and prints on recording paper using an electrophotographic system or an inkjet system.

  Conventionally, in an image forming apparatus that prints on recording paper using an electrophotographic method or an inkjet method, printing data transmitted from an externally connected host computer, digital camera, or the like, or recorded on a recording medium such as a flash memory A document, an image file, or the like is input, developed into a format that can be printed by an electrophotographic method or an inkjet method, and printed on a recording sheet.

  In such an image forming apparatus, as a format of input information, a controller unit that inputs a language format describing the arrangement and expression method of characters and images, etc., analyzes the language, and develops the bitmap format Generally, an engine unit that receives print data from a controller unit, conveys a recording sheet, and actually performs printing using a recording member such as a photosensitive drum or an ink jet head is used.

  In developing a bitmap in the controller unit, first, the input language is analyzed and converted into an intermediate processing format called a display list (hereinafter referred to as DL). This DL is a format that does not depend on the language type, and even when the image forming apparatus supports a plurality of types of languages, the difference is absorbed and converted into a format that the renderer can render. The DL is generated in units of objects such as characters, images, and graphics. Next, the generated DL is rendered on an object basis by a renderer and developed into a bitmap. After rendering processing, the developed bitmap is transferred to the engine unit for printing, but the rendering processing unit (band height) is processed by the engine unit so that the used memory capacity and processing speed are most efficient. It is set according to the unit (number of lines).

  Depending on the rendering method, this DL generation and rendering is performed for all objects even if the objects overlap. Depending on the number of objects that exist in each band and the degree of overlap between the objects, Render processing time changes.

  Next, regarding the conveyance and printing of the recording paper in the engine unit, when an ink jet head is used as a recording member, the leading end of the recording paper contained in the paper feed cassette or paper feed tray is a position where the ink jet head performs printing. (Hereinafter referred to as paper feed). After feeding is completed, printing is performed for one recording sheet while repeating printing by the inkjet head and conveyance of the recording sheet, and the recording sheet is discharged to the discharge port after printing is completed. When printing a plurality of pages, a so-called advance paper feed process is performed to improve the throughput. This is because when it is determined that there is a page to be printed (hereinafter referred to as the next page) during printing of a certain page (hereinafter referred to as the previous page), the next page is printed immediately after the printing of the previous page is completed. In this process, the recording paper for the next page is fed in advance during printing of the previous page. By doing so, the time required for printing on the second and subsequent pages is substantially only the printing time, so that the throughput can be improved.

As another means of improving throughput, a printing apparatus equipped with a paper feed option unit is shorter when the image development time during printing is shorter than the paper transport time from the designated paper feed destination. Some have been changed to another paper source that can be transported in time. (For example, refer to Patent Document 1).
Japanese Patent No. 3507187

  However, the image forming apparatus described above has the following drawbacks. As the processing flow for the second and subsequent pages, when the next page is found to be present, the preceding paper feed is performed, and then processing is performed in the order of rendering, bitmap transfer to the engine unit, and printing. The time varies depending on the number of objects and the degree of overlap between objects, and the time increases as the number of objects increases and the overlap between objects increases. In this case, it takes time until the printing is started after the preceding paper feeding, and the state where the recording paper is fed continues for a long time. If the user cancels printing in this state, the blank recording paper that has already been fed will be ejected, and the user will have to re-accommodate the ejected recording paper in the paper cassette or paper tray. There was a problem that it was not easy to use.

The present invention has been made in view of the above-described aspects, and aims to provide each means for solving the problems of the following items. That is,
1) The first purpose is to prevent the possibility that an extra blank sheet will be discharged when the user cancels the print job if the state in which the paper has already been supplied and the printing is not started continues for a long time. Thus, it is intended to improve the usability and the printing throughput.

  2) The second purpose is to develop the image information in units of pages, and to achieve both usability and improvement in print throughput.

  3) The second purpose is to develop the image information in band units, and to achieve both usability and further improvement in print throughput.

  Therefore, the present invention intends to achieve each of the above objects by providing an image forming apparatus having the configuration shown in the following corresponding items (1) to (3).

  (1) In an image forming apparatus that forms an image on a recording sheet and performs printing, an input unit that inputs information to be printed, a developing unit that analyzes information input by the input unit and develops the image information, A first predicting unit that predicts a time until the end of expansion before starting the expansion by the expansion unit, a paper feeding unit that feeds the recording paper, and a parallel operation with the expansion unit. Printing means for printing the developed image information on the recording paper fed by the paper feeding means, second prediction means for predicting the time until printing by the printing means is completed, and the developing means Comparison means for comparing the print end time of the currently printed page predicted by the second prediction means with the expansion end time predicted by the first prediction means before starting the expansion of the second and subsequent pages by As a result of the comparison by the comparison means, if the development end time is earlier than the printing end time, the recording paper of the next page is fed before starting the development, and if the development end time is later than the printing end time, An image forming apparatus characterized in that the recording paper for the next page is fed.

  (2) The image formation according to (1), wherein the expansion unit expands the image information on a page basis, and the first prediction unit predicts a time until the expansion of one page is completed. apparatus.

  (3) The expansion means expands the image information in band units obtained by dividing one page by a predetermined number of lines, and the first prediction means predicts a time until expansion of the top band of the page is completed. The image forming apparatus according to (1), wherein

  According to the present invention, when two or more pages are continuously printed, the print end time of the previous page and the render end time of the next page are predicted and compared, and if the print end is earlier than the end of rendering, the preceding paper feed is not performed. When the printing finishes earlier than the end of rendering, the paper is fed in advance, so it is possible to shorten the time until the completion of printing when inputting printing information with a fast rendering, and input printing information that takes a long time to render. In this case, it is possible to prevent an extra blank sheet from being discharged when the user cancels the job, and there is an effect that it is possible to provide an image forming apparatus that achieves both improved printing throughput and usability. Furthermore, there is an effect that the printing throughput can be further improved by performing rendering and printing in band units.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a configuration of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an image forming apparatus, which prints on printing paper based on information input from the outside or information previously held inside. Reference numeral 2 denotes a host computer (hereinafter referred to as a host), which is connected to the image forming apparatus 1 via a cable 3, and print data and information for controlling the image forming apparatus 1 (hereinafter referred to as print information). ). A digital camera 4 is connected to the image forming apparatus 1 via a cable 5 and transfers print information to the image forming apparatus 1. A flash memory insertion slot 6 is inserted into the flash memory 7, and the image forming apparatus 1 inputs print information stored in the flash memory 7. Reference numeral 8 denotes a paper feed cassette on which a predetermined amount of printing paper can be set. In the figure, the paper feed cassette has a two-stage configuration, and two types of paper of different sizes and types can be set. Reference numeral 9 denotes a paper discharge port for discharging the printed paper. An operation key 10 is a member for performing various settings relating to the operation of the image forming apparatus 1 or performing operations when the image forming apparatus 1 is used alone. Reference numeral 11 denotes a display panel for displaying the status of the image forming apparatus 1 and setting contents when operation settings of the image forming apparatus 1 are performed using the operation keys 10. The type of paper to be printed, the print image quality, and the like can be set with the operation keys 10 and the display panel 11. A power switch 12 is a switch for turning on / off the power of the image forming apparatus 1.

  FIG. 2 is a diagram showing an outline of the configuration of the image forming apparatus 1. In FIG. 1, the image forming apparatus 1 includes a controller unit 13 and an engine unit 14. The controller unit 13 receives print information from the host 2, the digital camera 4, and the flash memory 7, performs processing such as analysis of the print information, and generates print data in a format that can be printed by the engine unit 14. Further, the input of the operation key 10 is accepted, the operating environment of the image forming apparatus 1 is set, and the display panel 11 displays the status of the image forming apparatus 1 and a display for prompting the user to operate with the operation key 10. Etc. The engine unit 14 feeds paper, prints the print data generated by the controller unit 13 and discharges the print data. When an abnormality such as a paper jam or out of paper occurs in the engine unit 14, the controller unit 13 is notified, and the controller unit 13 displays that the abnormality has occurred on the display panel 11, or notifies the host 2 or the digital camera 4. Perform notification processing.

  FIG. 3 is a block diagram showing an internal configuration of the controller unit 13. In the figure, 21 is a controller microcomputer, 22 is a system memory, 23 is an interface circuit (hereinafter referred to as I / F circuit), 24 is a reception buffer, 25 is a DL memory, 26 is a renderer, 27 is a controller memory, and 28 is a resolution. A gradation conversion circuit.

  Next, the operation in the block diagram of FIG. 3 will be described. The controller microcomputer 21 controls all control such as analysis of print information input from the outside, image processing, and conversion processing to a bitmap. The flow of print data is as follows. The print information input from the host 2, the digital camera 4, and the flash memory 7 is stored in the reception buffer 24 via the I / F circuit 23, and the I / F circuit 23 notifies the controller microcomputer 21 that the print information has been received. The The print information includes a page description language (hereinafter referred to as PDL) that describes how to arrange and represent characters and images on a print sheet in units of pages. The controller microcomputer 21 analyzes the received print information, converts it into a display list (hereinafter referred to as DL) format, and stores it in the DL memory 25. The DL is rendered by the renderer 26, converted into a bitmap having a predetermined gradation and resolution, and stored in the controller memory 27. The bitmap is converted into a resolution and gradation printable by the engine unit 14 by the resolution / gradation conversion circuit 28 and sent to the engine unit 14.

  The operation content of the operation key 10 is input to the controller microcomputer 21 and appropriate processing is performed according to the input content. Further, when a printing situation or an error occurs from the engine unit 14, the contents are notified to the controller microcomputer 21, displayed on the display panel 11, or notified to the host 2 or the digital camera 4.

  FIG. 4 is a diagram illustrating an internal configuration of the engine unit 14 and illustrates an image when the image forming apparatus 1 is viewed from the side. In the figure, 41 is an engine microcomputer, 42 is an engine memory, 43 is a carriage, 44 is a carriage motor, 45 is a print head, 46 is a head driver, 47 is a roller, 48 is an LF motor, 49 is printing paper, and 50 is paper supply. A paper sensor, 51 is a paper discharge sensor, and 52 is a program memory.

  Next, the operation in the block diagram of FIG. 4 will be described. The engine microcomputer 41 controls all control such as feeding and discharging of the printing paper 49 and control of the print head. The bitmap sent from the controller unit 13 is stored in the engine memory 42. The printing paper 49 is fed and discharged by driving the LF motor 48 and rotating the roller 47. Whether the paper feed and paper discharge are operating normally is determined by detecting the presence or absence of the print paper 49 by the paper feed sensor 50 and the paper discharge sensor 51. The print head 45 is integrated with the carriage 43 and is driven by a head driver 46. The carriage 43 reciprocates in the direction perpendicular to the paper surface and the conveyance direction of the printing paper by the carriage motor 44, and prints on the printing paper 49 by the print head 45. When the paper feed sensor 50 and the paper discharge sensor 51 detect that the printing paper 49 is jammed, printing is stopped and the controller unit 13 is notified.

  FIG. 5 is a flowchart showing the operation of the embodiment of the present invention. This flowchart is a program diagram showing a program flow built in the system memory 22 of FIG. 3 and the program memory 52 of FIG. 4 and processed by the controller microcomputer 21 and the engine microcomputer 41. The controller microcomputer 21 and the engine microcomputer 41 cooperate with each other. Then, the control operation is executed according to the program flow.

  The flow in FIG. 9 shows a process of switching whether to perform the second page advance feeding by receiving the print job for page 2 and comparing the print end time of the first page with the render end time of the second page. ing. Rendering is performed in units of pages.

  Below, it demonstrates along each step of a flow.

  Step 101 (denoted as S101 in the figure, the same applies hereinafter): Waits until a print job is received from the host 2, the digital camera 4, and the flash memory 7. When received, the I / F circuit 23 notifies the controller microcomputer 21 and stores it in the reception buffer 24.

  Step 102: Analyze the PDL data in the received print job, and generate a DL for the first page. DL is data in a format necessary for rendering processing by the renderer 26.

  Step 103: Predict the printing end time of the first page. Time prediction is performed by calculation based on setting information such as the size of paper to be printed, resolution, color / monochrome, print quality, and the like and the capability of the engine unit. The prediction result is (1).

  Step 104: Feed the first page of paper. Paper feed is performed by rotating the roller 47 by the LF motor 48 and transporting the printing paper 49 to a position where printing can be started. The transport position is controlled by monitoring the signal output of the paper feed sensor 50.

  Step 105: The DL generated in step 102 is input to the renderer 26, and the first page is rendered. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 106: The bitmap of the first page is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 107: Send out the bitmap for one page converted in step 106 to the engine unit 14 to instruct the start of printing of the first page. The transmitted bitmap is stored in the engine memory 42. The engine unit 14 prints the bitmap stored in the engine memory 42 at an appropriate timing. Specifically, the printing paper 49 is conveyed by the LF motor 48 and the roller 47, and printing is performed on the printing paper 49 by the print head 45 while the carriage 43 is reciprocated by the carriage motor 44. The printing position of the printing paper 49 is controlled based on the driving amount of the LF motor 48 and the detection results of the paper feed sensor 50 and the paper discharge sensor 51 in the transport direction, and the moving direction of the carriage 43 on the driving amount of the carriage motor 44. Based on.

  Step 108: Analyze the PDL data in the received print job and generate a DL for the second page.

  Step 109: Predict the rendering end time of the second page. Since rendering is processed for each object, the larger the number of objects present in the band, the longer the rendering time. In addition, since rendering is performed for each object even when the objects overlap each other, the larger the overlapping area, the longer the rendering time. In this step, the rendering time is predicted by analyzing the number of objects and the degree of overlap based on the DL generated in step 108. The prediction result is (2).

  Step 110: The printing end time of the first page predicted in Step 103 ((1)) is compared with the rendering end time of the second page predicted in Step 109 ((2)). From (1) to (2) If this is early, the process proceeds to step 111; otherwise, the process proceeds to step 114.

  Step 111: The second page is fed in advance. This feeding is performed during the printing process for the first page, and the engine microcomputer 41 feeds the second page while checking the progress of the printing process for the first page. To complete the paper feeding.

  Step 112: The DL generated in step 108 is input to the renderer 26, and the second page is rendered. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 113: The second page bitmap is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 114: The DL generated in step 108 is input to the renderer 26 and the second page is rendered. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 115: The bitmap of the second page is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 116: Paper for the second page is fed. The processing here is the same as the feeding of the first page in step 104.

  Step 117: Send out the bitmap for one page converted in step 113 or 115 to the engine unit 14 to instruct the start of printing of the second page. The transmitted bitmap is stored in the engine memory 42. The engine unit 14 immediately prints the bitmap stored in the engine memory 42 when the printing of the first page is finished. If the printing is not finished yet, the engine unit 14 prints it.

  Step 118: If printing has not been completed up to the last page (2 pages in this flowchart), the process waits until it is completed, and if it has been completed, the processing of this flowchart is terminated.

  In the above operation flow, a print job is received in step 101, the processing from DL generation of the first page to printing start is executed in steps 102 to 107, and the DL generation of the second page is executed in steps 108 to 117. Processing up to the start of printing is performed. In step 103, the printing end time of the first page is predicted, and in step 109, the rendering end time of the second page is predicted. In step 110, the two are compared. As a result of comparison, when the rendering end time of the second page is earlier, the processing from step 111 to step 113 is performed, and the preceding paper feeding is performed before the second page rendering. At this time, the first page is still being printed, and the feeding of the second page is completed at the end of the subsequent printing, so printing of the second page can be started immediately. On the other hand, if the print end time of the first page is earlier, the processing from step 114 to step 116 is performed, and paper feeding is performed after the rendering of the second page and the resolution / gradation conversion processing. At the end of printing the first page, the second page is still being rendered and no paper is fed.

  By doing this, in the case of PDL data that does not take a long time for rendering, the preceding paper feeding is performed, so that continuous pages can be printed faster. In the case of PDL data that takes a long time to render, the preceding paper feeding is not performed, and the paper is fed and printed after the rendering is completed. When the job is cancelled, no extra blank paper is discharged and the usability can be improved.

  FIG. 6 is a flowchart showing the operation of the embodiment of the present invention. The flowchart of FIG. 6 is a program diagram showing a program flow built in the system memory 22 of FIG. 3 and the program memory 52 of FIG. 4 and processed by the controller microcomputer 21 and the engine microcomputer 41. Execute the control operation in accordance with the program flow in cooperation.

In the flowchart of FIG. 5, a print job for page 2 is received, and the print end time for page 1 is compared with the render end time for the first band on page 2, and whether or not to perform advance feeding for page 2 is switched. Processing is shown. Rendering is performed in units of bands obtained by dividing one page into a predetermined number of lines.
Below, it demonstrates along each step of a flow.

  Step 201: Wait until a print job is received from the host 2, the digital camera 4, and the flash memory 7. When received, the I / F circuit 23 notifies the controller microcomputer 21 and stores it in the reception buffer 24.

  Step 202: Analyze the PDL data in the received print job, and generate a DL for the first page. DL is data in a format necessary for rendering processing by the renderer 26.

  Step 203: The printing end time of the first page is predicted. Time prediction is performed by calculation based on setting information such as the size of paper to be printed, resolution, color / monochrome, print quality, and the like and the capability of the engine unit. The prediction result is (3).

  Step 204: Feed the first page of paper. Paper feed is performed by rotating the roller 47 by the LF motor 48 and transporting the printing paper 49 to a position where printing can be started. The transport position is controlled by monitoring the signal output of the paper feed sensor 50.

  Step 205: The DL generated in step 202 is input to the renderer 26 to perform rendering processing for one band on the first page. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 206: The bitmap for one band of the first page is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 207: The bitmap for one band converted in step 206 is sent to the engine unit 14 to instruct the start of printing for one band on the first page. The transmitted bitmap is stored in the engine memory 42. The engine unit 14 prints the bitmap stored in the engine memory 42 at an appropriate timing. A specific processing method is the same as step 107 in FIG.

  Step 208: It is determined whether or not the start of printing of all the bands on the first page has been instructed. If there is a band that has not been instructed to start printing yet, the process returns to Step 205 to process the remaining bands. If the start of printing is instructed, the process proceeds to step 209.

  Step 209: Analyze the PDL data in the received print job and generate a DL for the second page.

  Step 210: Predict rendering end time of the first band of the second page. In this step, the rendering time is predicted by analyzing the number of objects and the degree of overlap based on the DL generated in step 209. The prediction result is (4).

  Step 211: The printing end time ((3)) predicted for the first page predicted in step 203 is compared with the rendering end time ((4)) for the first band of the second page predicted in step 210. From (3) If (4) is early, the process proceeds to step 212; otherwise, the process proceeds to step 217.

  Step 212: The second page is fed in advance. This feeding is performed during the printing process for the first page, and the engine microcomputer 41 feeds the second page while checking the progress of the printing process for the first page. To complete the paper feeding.

  Step 213: The DL generated in step 209 is input to the renderer 26, and rendering processing for one band of the second page is performed. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 214: The bitmap for one band on the second page is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 215: The bitmap for one band converted in step 214 is sent to the engine unit 14 to instruct the start of printing for one band on the second page. The transmitted bitmap is stored in the engine memory 42. The engine unit 14 prints the bitmap stored in the engine memory 42 at an appropriate timing.

  Step 216: It is determined whether printing of all bands on the second page has been instructed. If there is a band that has not been instructed to start printing, the process returns to step 213 to process the remaining bands. If the start of printing is instructed, the process proceeds to step 223.

  Step 217: The DL generated in step 209 is input to the renderer 26, and rendering processing for one band of the second page is performed. The result of the rendering process is stored in the controller memory 27 as a bitmap.

  Step 218: The bitmap for one band of the second page is read from the controller memory 27, and the resolution and gradation conversion circuit 28 converts the resolution and gradation into a format printable by the engine.

  Step 219: It is determined whether or not all bands on the second page have been rendered. If there are bands that have not been rendered yet, the process returns to step 217 to process the remaining bands, and all bands have been rendered. If YES, go to Step 220.

  Step 220: Feed the second page of paper. The processing here is the same as the feeding of the first page in step 204.

  Step 221: The bitmap for one band converted in step 218 is sent to the engine unit 14 to instruct the start of printing for one band on the second page. The transmitted bitmap is stored in the engine memory 42, and the engine unit 14 prints the bitmap stored in the engine memory 42.

  Step 222: It is determined whether printing of all bands on the second page has been instructed. If there is a band that has not been instructed to start printing, the process returns to step 221 to process the remaining bands. If the start of printing is instructed, the process proceeds to step 223.

  Step 223: If printing has not been completed up to the last page (2 pages in this flowchart), the process waits until it is completed, and if completed, the processing of this flowchart is terminated.

  In the above operation flow, a print job is received in step 201, processing from DL generation for the first page to printing start in steps 202 to 208, and from generation of DL for the second page in steps 209 to 222. Processing up to the start of printing is performed. Rendering on each page is done in band units. In step 203, the printing end time of the first page is predicted, and in step 210, the rendering end time of the first band of the second page is predicted. In step 211, both are compared. If the rendering end time of the first band of the second page is earlier than the result of comparison, the processing from step 212 to step 216 is performed, and the preceding paper feeding is performed before the rendering of the first band of the second page. At this time, the first page is still being printed, and the feeding of the second page is completed at the end of the subsequent printing, so printing of the second page can be started immediately. On the other hand, if the print end time of the first page is earlier, the processing from step 217 to step 222 is performed, and paper feeding is performed after rendering of all bands of the second page and resolution / gradation conversion processing. At the end of printing the first page, the first band of the second page is still being rendered, and no paper is fed.

  Also in this embodiment, as in the first embodiment, in the case of PDL data that takes a long time to render, since the preceding paper feeding is not performed, the state in which the paper feeding and printing are not started does not continue for a long time. When the job is canceled, extra white paper is not discharged. In addition, in the case of PDL data with high rendering speed, the preceding paper feeding is performed, so that the throughput in printing continuous pages is improved. Furthermore, since rendering and printing are performed in band units in this embodiment, the time for the controller unit and engine unit to operate in parallel is longer than in the processing in page units in the first embodiment. Since the time can be shortened, further improvement in throughput can be realized.

1 is a perspective view illustrating a configuration of an image forming apparatus according to first and second embodiments. 1 is a diagram illustrating an outline of a configuration of an image forming apparatus according to first and second embodiments. 1 is a diagram illustrating an outline of a configuration of an image forming apparatus according to first and second embodiments. 1 is a diagram illustrating an outline of a configuration of an image forming apparatus according to first and second embodiments. The flowchart which shows operation | movement of 1st Example. The flowchart which shows operation | movement of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Host 3 Cable 4 Digital camera 5 Cable 6 Flash memory insertion port 7 Flash memory 8 Paper feed cassette 9 Paper discharge port 10 Operation key 11 Display panel 12 Power switch 13 Controller unit 14 Engine unit 21 Controller microcomputer 22 System memory 23 I / F circuit 24 Reception buffer 25 DL memory 26 Renderer 27 Controller memory 28 Resolution / gradation conversion circuit 41 Engine microcomputer 42 Engine memory 43 Carriage 44 Carriage motor 45 Print head 46 Head driver 47 Roller 48 LF motor 49 Printing paper 50 Supply Paper sensor 51 Paper discharge sensor 52 Program memory

Claims (3)

In an image forming apparatus for forming an image on a recording sheet and performing printing,
An input means for inputting information to be printed;
Expansion means for analyzing the information input by the input means and expanding the image information;
First predicting means for predicting the time until the end of expansion before starting the expansion by the expansion means;
Paper feeding means for feeding the recording paper;
A printing unit that operates in parallel with the developing unit and prints the image information developed by the developing unit on the recording paper fed by the paper feeding unit;
Second predicting means for predicting a time until printing by the printing means is completed;
A comparison comparing the print end time of the currently printed page predicted by the second prediction unit and the expansion end time predicted by the first prediction unit before starting the expansion of the second and subsequent pages by the expansion unit. Means,
As a result of the comparison by the comparison means, if the development end time is earlier than the printing end time, the recording paper of the next page is fed before starting the development, and if the development end time is later than the printing end time, An image forming apparatus characterized in that the recording paper for the next page is fed.   The image forming apparatus according to claim 1, wherein the developing unit develops image information in units of pages, and the first predicting unit predicts a time until the development of one page is completed.   The expansion unit expands image information into band information obtained by dividing one page into a predetermined number of lines, and the first prediction unit predicts a time until expansion of the top band of the page is completed. The image forming apparatus according to claim 1.

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