JP7625800B2 - Image forming apparatus, image forming control method, and image forming program - Google Patents

Description

The present invention relates to an image forming apparatus, an image forming control method, and an image forming program.

In a printing device, in order to increase the printing speed and improve productivity, the "processing of generating drawing data by an information processing device," "image processing to convert the drawing data into print output data," and "processing of transferring the print output data to the image forming unit (engine)" must be performed in synchronization with the transport of the paper to be printed.

For this reason, conventionally, multiple page buffer memories are provided in the data transfer path from the information processing device to the engine. Then, the process of writing the print output data generated by converting the drawing data to the page buffer, and the process of reading and transferring the print output data from the page buffer memory at the timing requested by the engine are performed in parallel. This allows for continuous transfer of print output data while absorbing the difference between the timing when the information processing device generates the drawing data and the timing when the engine requests the transfer of the print output data.

However, depending on the contents of the print document or the contents of image processing, it may take time to generate the drawing data, and the image processing that converts the drawing data into print output data may take time, which may result in a delay in the generation of the print output data. If the generation of the print output data is delayed, the print output data may be in the middle of being written to the page buffer memory when the engine requests the print data, or no print output data may have been written to the page buffer memory at all.

As a result, even though the print paper has been transported to the image-forming position, the paper output may have missing images or may be blank, resulting in abnormal images being mixed into the print output. For this reason, conventional printing devices notify the user of an error when the transfer process of print output data to the image forming unit (engine) is not completed in time, and also stop the printing operation to prevent the mixing of abnormal images.

Patent document 1 (JP 2008-044172 A) discloses an image forming device that can detect duplicate printing and the like without having a configuration for reading the print output results. This image forming device compares the nth page of raster data generated by a raster image processor with pages (n-1) to (n-m) of the preceding raster data. If raster data matching page n is detected for the preceding page, it determines that duplicate printing will occur and performs error processing such as notifying the user and stopping printing. This makes it possible to prevent duplicate printing from occurring.

However, if an error occurs, there is a risk that the printer will output paper with an abnormal image printed on it, such as a paper with a missing image printed on it, or a paper with only one side printed even though the paper is supposed to be double-sided.

The present invention has been made in consideration of the above-mentioned problems, and aims to provide an image forming device, an image forming control method, and an image forming program that prevent the output of abnormal images.

In order to solve the above-mentioned problems and achieve the object, the present invention provides an image forming device that sequentially writes and reads printing information to multiple storage units including a first storage unit and a second storage unit, and supplies the printing information read from each storage unit to an image forming unit to print on paper, the image forming unit having a delay detection unit that detects a delay in starting to write the printing information to each storage unit, and a control unit that, when a delay in starting to write is detected by the delay detection unit, ejects paper that has already been fed and controls the image forming unit to stop feeding paper from the paper feeding unit, thereby interrupting the printing process, and the delay detection unit detects a delay in starting to write when the start of reading from the first storage unit has not been notified of the start of writing to the second storage unit.

The present invention has the effect of preventing the output of abnormal images.

FIG. 1 is a system configuration diagram of a printing system according to an embodiment of the present invention. FIG. 2 is a block diagram of the DFE. FIG. 3 is a block diagram of the image forming apparatus. FIG. 4 is a diagram illustrating a schematic configuration of the image forming unit. FIG. 5 is a block diagram of a printing system serving as a comparative example. FIG. 6 is a block diagram of a printing system according to the embodiment. FIG. 7 is a diagram for explaining write/read control for the page buffer memory. FIG. 8 is a flowchart showing the flow of the write/read operation to the page buffer memory and the operation of determining whether a transfer error has occurred. FIG. 9 is a diagram for explaining write/read control for the page buffer memory in the printing system according to the second embodiment. FIG. 10 is a flowchart showing the flow of the write/read operations to/from the page buffer memory and the operation of determining whether a transfer error has occurred in the printing system of the second embodiment. FIG. 11 is a flowchart for explaining the flow of operations from the printing stop operation due to an error notification to the printing restart operation.

The printing system according to the embodiment will be described below with reference to the attached drawings.

[First embodiment]
(System Configuration)
Fig. 1 is a diagram showing the system configuration of a printing system according to a first embodiment. As shown in Fig. 1, the printing system according to the first embodiment includes one or more client personal computer devices (client PCs) 101, information processing devices (DFEs: Digital Front Ends) 102, and image forming devices 103. The client PCs 101, DFEs 102, and image forming devices 103 are connected to one another via a predetermined communication cable or a predetermined network such as a LAN (Local Area Network).

(Client PC configuration)
The client PC 101 has a typical personal computer configuration connected to a display device such as a liquid crystal display, and input devices such as a mouse and a keyboard. That is, the client PC 101 has a storage unit such as a CPU (Center Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a HDD (Hard Disk Drive), and an SSD (Solid State Drive). The CPU operates based on an operation system program and a print control program stored in the storage unit, and forms a print job of an image that a user wishes to print, and transmits the print job to the DFE 102.

(Configuration of DFE)
Fig. 2 is a block diagram of the DFE 102. As shown in Fig. 2, the DFE 102 has a CPU 201, a ROM 202, a RAM 203, a HDD (or SSD) 204, an external interface (I/F) 205, and an image output interface (image output I/F) 206. The client PC 101 is connected to the I/F 205. The image forming apparatus 103 is connected to the image output I/F 206.

Such a DFE 102 uses a RIP (Raster Image Processor) engine to create drawing data for each color plate based on the print job received from the client PC 101, and transmits the data to the image forming device 103.

(Configuration of Image Forming Apparatus)
Fig. 3 is a block diagram of the image forming apparatus 103. As shown in Fig. 3, the image forming apparatus 103 has a CPU 301, a ROM 302, a RAM 303, a HDD (or SSD) 304, an external interface (I/F) 305, an image processing unit 306, and an image forming unit 307. The I/F 305 is connected to the DFE 102. The client PC 101 is connected to the DFE 102.

The ROM 302 stores an image formation program. Based on the image formation program, the CPU 301 controls the image formation operation by the image processing unit 306 and the image forming unit 307, as described below.

The image processing unit 306 performs image correction processing on the drawing data acquired from the DFE 102 in accordance with the engine output characteristics, and converts the data into print output data that can be printed out by the image forming unit 307. The image forming unit 307 transfers and outputs onto paper an image, etc., that corresponds to the print output data generated by the image processing unit 306.

(Configuration of Image Forming Unit)
Fig. 4 is a diagram showing a schematic configuration of the image forming unit 307. As shown in Fig. 4, the image forming unit 307 is a so-called tandem type image forming unit, and has photoconductor drums 403Y, 403M, 403C, and 403K (sometimes collectively referred to as photoconductor drums 403) of the respective colors of yellow, magenta, cyan, and key plate (black).

The photosensitive drums 403 are arranged in the order of photosensitive drums 403Y, 403M, 403C, and 403K along the intermediate transfer belt 402, from the upstream side in the transport direction of the intermediate transfer belt 402, on which an intermediate transfer image is formed to be transferred to paper fed from the paper feed tray 400 and transported by the transport rollers 401.

A full-color image is formed by transferring the images of each color developed with the toner of each color onto the surface of the photosensitive drums 403 of each color in a superimposed manner onto the intermediate transfer belt 402. The full-color image formed on the intermediate transfer belt 402 is transferred onto the surface of the paper transported along the path by the function of the transfer roller 404 at the position closest to the paper transport path indicated by the dashed line in FIG. 4. The paper with the image formed on its surface is transported further, and the image is fixed (image formed) by the fixing roller 405.

In the case of double-sided printing, the paper on which an image has been formed on the front side is transported to the reversal path 407 in the transport path, where it is inverted, and then transported again to the position of the transfer roller 404, where an image is formed on the back side of the paper.

The paper on which the image has been fixed (paper on which printing has been completed) is discharged to paper discharge outlet 406-1 or paper discharge outlet 406-2. If there are multiple paper discharge outlets, the paper discharge outlet from which the paper is output may be switched depending on the print job.

(Comparative Example Printing System)
Next, a printing system that is a comparative example of the printing system of the first embodiment will be described. Fig. 5 is a block diagram of the printing system that is the comparative example. As shown in Fig. 5, in the printing system that is the comparative example, the image processing unit 306 of the image forming apparatus 103 has a print processing order determination unit 501 and a color plate processing unit 502. In addition, the image forming unit 307 has a transfer error detection unit 508.

The color plate processing unit 502 has a print output data generation unit 503, an output unit 504, and an output control unit 507. The output unit 504 has a first page buffer memory 505 and a second page buffer memory 506.

In this comparative printing system, when the DFE 102 receives a print job from the client PC 101, it forms a print request including information such as print image size, output paper size, color plates used within the page, resolution, print surface, and print management page ID. The print request is formed based on the print job information, and is print management information for notifying the paper type, image size, page management ID information, image processing, print processing contents, etc. required for printing. This print request is supplied to the print processing order determination unit 501 of the image forming device 103.

In addition to text, image data, and layout information, a print job also includes information indicating the type of paper to be printed on, print commands that specify the details of the print process, etc.

The print processing order determination unit 501 determines the page order for executing the print processing based on the print request, forms print information by adding print processing order information to the print request information, and notifies the image forming unit 307. The print processing order determination unit 501 also makes a print data request to the DFE 102 according to the print processing order. This print data request is a data transfer request for the next required drawing data using the page management ID according to the execution order of the print processing.

When the color plate processing unit 502 of the image forming device 103 acquires the drawing data (Y/M/C/K) from the DFE 102, it performs image processing for each output color plate that the image forming unit 307 can handle. The color plate processing unit 502 has multiple processing functions corresponding to the number of output color plates Y/M/C/K. The drawing data is print image data in which the text and image information of the print job is converted into a raster image for each color plate Y, M, C, and K.

The print output data generation unit 503 performs gradation processing such as dithering and correction processing such as gamma processing that matches the output characteristics on the drawing data for each color plate from the DFE 102 so that it can be output by the image forming unit 307.

The output unit 504 temporarily stores one page of print output data that has been image-processed by the print output data generation unit 503, and transmits this print output data to the image forming unit 307 via the output control unit 507. At this time, the output unit 504 switches between the first page buffer memory 505 and the second page buffer memory 506 to write and read data. This enables continuous transfer of print output data. The print output data is image data that has been converted into a format that can be output by the image forming device 103 by performing halftone processing and gamma correction processing on the drawing data for each color plate.

The print output data generation unit 503 of the image processing unit 306 converts the drawing data acquired in the order of printing processing into print output data in a bitmap format that can be output by the image forming unit 307. In addition to this conversion process, the print output data generation unit 503 also performs image processing such as correction processing such as color correction and print position adjustment according to the output characteristics of the image forming unit 307 and the user's requests.

Even if the print output data is for the same page, in the case of image forming unit 307 in which photoconductor drums 403Y, 403M, 403C, and 403K for each color are arranged in tandem as shown in FIG. 4, the transfer of the print output data to image forming unit 307 is at different times for each color plate. For this reason, the print data request and the drawing data corresponding to this print data request are transferred for each color plate, and image processing in image processing unit 306 is also performed for each color plate.

The image processing unit 306 temporarily stores the print output data for each color plate in the first page buffer memory 505 and the second page buffer memory 506 of the output unit 504, the amount of print data corresponding to the print data size notified in the print information. Then, the image processing unit 306 reads out the print output data for each color plate from the first page buffer memory 505 or the second page buffer memory 506 at the timing required by the image forming unit 307, and transfers it to the image forming unit 307.

In this case, continuous print output is supported by using two pages of page buffer memory as toggle buffer memory that alternates between the page buffer memory into which the data generated by the print output data generation unit 503 is written and the page buffer memory from which the data to be output to the image forming unit 307 is read.

The print processing order determination unit 501 checks the transfer status of the print data in the color plate processing 502 using the print data transfer status notification, and if the print output has been completed successfully, it sends an output result notification to the DFE 102 indicating that the print output has been completed successfully. The output result notification is a page management ID for notifying the DFE 102 of the color plate for which the print output has been completed. When the DFE 102 receives this output result notification, it moves on to the next drawing data generation process. In addition, the DFE 102 notifies the completion of the print output by sending the print output result including the page management ID to the upper device, the client PC 101.

Here, in order to maintain the printing speed and productivity through continuous print output, it is necessary to transfer the print output data to the image forming unit 307 without delaying the timing for forming an image on the transported paper.

However, a delay in the generation of drawing data in DFE 102 may cause a delay in the transfer of the drawing data, and may also cause a delay in the processing of print output data generation unit 503, which may cause a delay in writing and reading print output data to and from page buffer memories 505 and 506. If such a delay causes a delay in sending print output data to image forming unit 307, or if print output data cannot be sent to image forming unit 307, an abnormal image such as a missing image or a blank page is output, reducing printing productivity.

In order to prevent such inconveniences of outputting abnormal images, in the printing system of the comparative example, the transfer error detection unit 508 of the image forming unit 307 detects whether the necessary print output data is transferred when executing the print process. If the print output data is not transferred, it means that an abnormality (delay) has occurred in the upstream device, the image processing unit 306 or the DFE 102. For this reason, the transfer error detection unit 508 notifies the print processing order determination unit 501 of the image processing unit 306 of an error notification including the occurrence of an error and a page management ID indicating the color plate page where the error occurred. In addition, the transfer error detection unit 508 monitors the transfer status for each color plate, and notifies the image processing unit 306 for each color plate when an error is detected. In addition, the transfer error detection unit 508 also controls the stop of the printing operation of the image forming unit 307 to prevent the output of an abnormal image.

The print processing order determination unit 501 transmits interruption information indicating pages that have not been printed successfully to the DFE 102 in response to the error notification and print data transfer status notification from the transfer error detection unit 508. The print data transfer status notification is a status management signal that triggers a transition to print processing interruption processing when it is determined that the transfer of print output data will not be in time for the transfer output processing in the image forming unit. The DFE 102 notifies the client PC 101 of the interruption processing result indicating pages that have not been printed based on the interruption information.

To continue the print job that was instructed when the error occurred, the user selects "continue printing" via the operation panel after resolving the error state of the device. When "continue printing" is selected, the DFE 102 generates a print request instructing the image forming device 103 to resume printing from the page that was normally printed, and supplies the request to the image forming device 103. This allows the print process to be resumed from the page that was interrupted.

(Problems with the Comparative Example)
In such a printing system as a comparative example, the transfer error detection unit 508 detects an error by checking whether or not the print output data required for the execution of the printing process is transferred. However, in the printing system as a comparative example, it is difficult to identify the part in the upstream device that is causing the error. Therefore, when the printing is stopped due to an error, the user needs to check the content of the error and resume the printing process after restoring the device to a printable state.

To restore the device to a printable state after an error has occurred, it is necessary to reset the entire image processing system, including the DFE 102 and the image forming device 103, and to turn the power of the image forming device 103 off and then on again, which causes a problem of downtime during which users' printing operations are halted.

(Operation of the Printing System of the Embodiment)
For this reason, in the case of the printing system of the first embodiment, whether the print output data will be ready in time is not determined when the print process is executed in the image forming unit 307, but is determined in advance based on the transfer status of the print output data in the upstream image processing unit 306.

Specifically, as shown in FIG. 6, in addition to the configuration of the comparative example described above, the printing system of the first embodiment includes a retransmission process determination unit 520 in the DEF 102 and an image forming device 103 that includes an image transfer monitoring unit 509. Note that the printing system of the first embodiment does not include the transfer error detection unit 508 that is provided in the image forming unit 307 of the comparative example.

The image transfer monitoring unit 509 includes a transfer status monitoring unit 510 (an example of a delay detection unit) and a transfer abnormality notification unit 511 (an example of a control unit). The transfer status monitoring unit 510 monitors the write/read status of each page buffer memory 505, 506 based on the buffer control status notification supplied from the output unit 504. The transfer abnormality notification unit 511 instructs the image forming unit 307 to suspend printing when a transfer abnormality such as a write delay or read delay in each page buffer memory 505, 506 is detected.

That is, the output unit 504 transmits a buffer control status notification indicating the write status of the print output data from the print output data generation unit 503 to each page buffer memory 505, 506 to the image transfer monitoring unit 509. The buffer control status notification is information for monitoring the transfer status of the print output data, and is information indicating the write status and read status of the page buffer memories 505, 506.

As the buffer control status notification, a "first write start detection notification" and a "first write completion detection notification" indicating the write status of print data to the first page buffer memory 505 are supplied to the image transfer monitoring unit 509. Also, as the buffer control status notification, a "first read start detection notification" and a "first read completion detection notification" of print data to the first page buffer memory 505 are supplied to the image transfer monitoring unit 509.

In addition, as buffer control status notifications, a "second write start detection notification" and a "second write completion detection notification" indicating the write status of print data to the second page buffer memory 506 are supplied to the image transfer monitoring unit 509. In addition, as buffer control status notifications, a "second read start detection notification" and a "second read completion detection notification" of print data to the second page buffer memory 506 are supplied to the image transfer monitoring unit 509.

As an example, the image transfer monitoring unit 509 monitors the amount of data written to or read from each page buffer memory 505, 506 based on the data size information of the print image indicated in the print request.

The output unit 504 starts writing data to each page buffer memory 505, 506 based on the print image size information notified in the print request, and sends a "first write start detection notification" or a "second write start detection notification" to the image transfer monitoring unit 509 when the first line of main scan image data has been written to an empty page buffer memory 505 or 506.

In addition, when all data for one page in the main scan and sub-scan portions has been written to each page buffer memory 505, 506, the output unit 504 transmits a "first write completion detection notification" or a "second write completion detection notification" to the image transfer monitoring unit 509.

In addition, when the output unit 504 starts reading the print output data to be transferred from the first page buffer memory 505 or the second page buffer memory 506 to the image forming unit 307, it sends a "first read start detection notification" or a "second read start detection notification" to the image transfer monitoring unit 509.

As an example, the output unit 504 monitors the amount of data read from each of the page buffer memories 505 and 506. Then, the output unit 504 detects the start of transfer when the image data for the first main scan line of each of the page buffer memories 505 and 506 has been read and transferred.

Also, as an example, the output unit 504 detects the completion of reading when the output of all image data for one page in the main scanning and sub-scanning directions to the image forming unit 307 is completed and each of the buffer memories 505 and 506 becomes empty. Then, the output unit 504 transfers a "first reading completion detection notification" or a "second reading completion detection notification" to the image transfer monitoring unit 509.

The transfer status monitoring unit 510 recognizes the write status and read status of each buffer memory 505, 506 based on such buffer control status notification from the output unit 504. Then, if the transfer status monitoring unit 510 determines that the write status and read status of each buffer memory 505, 506 will not be in time for the print output timing of the image forming unit 307, the transfer abnormality notification unit 511 instructs the image forming unit 307 to suspend printing.

The interruption instruction is information that instructs the image forming unit 307 to specify the output destination for pages that have not been printed correctly and to stop a print request that has not started, in association with the page management ID.

When the image forming unit 307 receives an interrupt instruction, it stops the print output operation and stops the feeding of new paper from the paper feed tray 400. The image forming unit 307 also switches to and discharges, to different paper output outlets 406-1 and 406-2, the paper for the print page that has been printed successfully, the paper for which part of the print image is missing because the print output operation has been stopped, or the paper for which printing has been completed on only one side of a double-sided print job.

In the case of single-sided printing, the pages are printed in order, but in the case of double-sided printing, the image forming unit 307 treats pages for which printing on both sides has been completed as pages that have been printed normally, and controls the discharge of pages for which printing has only been completed on one side, or blank pages for which no printing has been performed, to a different discharge destination (discharge outlet 406-1 or discharge outlet 406-2) from the normal printout. This prevents the inconvenience of incompletely printed paper being mixed in with the normal printout, and makes it easier to manage the normally output printout.

The print processing order determination unit 501 of the image processing unit 306 also associates pages that have been printed out normally or pages that have not been output due to an interruption instruction with page management IDs to form interruption information, and transmits this information to the DFE 102 of the upper device. The retransmission process determination unit 520 of the DFE 102 notifies the client PC 101 of the occurrence of the interruption process and the result of the interruption process. The client PC 101 recognizes the printed page based on the result of the interruption process, and notifies the user of the occurrence of the print interruption via the display unit (or the operation panel of the image forming device 103, etc.).

When the user selects to resume the printing process via the client PC 101, the client PC 101 continues the printing process by resending the print job from the page following the page that was successfully printed before the interruption.

In other words, the resend processing unit 520 determines the part of the interrupted print job where continued printing will be performed (the page following the page where printing completed normally) based on the interruption information, and notifies the client PC 101 of the interruption processing result, which is the result of this determination. Therefore, the client PC 101 resends the print job to resume printing from the page indicated in the interruption processing result. This makes it possible to continue printing from the part where printing was interrupted, rather than on a print job basis.

(Check operation for timing of completion of writing to page buffer memory)
Next, a check operation for the timing of writing completion to the page buffer memory will be described. When the transfer of print output data to the image forming apparatus 103 is completed, the transfer status monitoring unit 510 of the image transfer monitoring unit 509 checks whether the transfer of the next print data to the page buffer memories 505 and 506 has been completed.

The transfer status monitoring unit 510 determines whether the print output data is not ready in the page buffer memories 505 and 506 because the transfer of the drawing data or the processing of the print output data generating unit 503 is not in time. When the transfer status monitoring unit 510 detects a transfer abnormality, the transfer abnormality notification unit 511 supplies an interruption instruction to the image forming unit in order to interrupt the printing process after the relevant page and to perform a purge process that switches the paper output destination of the incomplete print output result.

(Write/read control for page buffer memory)
Next, the write/read control for each of the page buffer memories 505 and 506 will be described with reference to Fig. 7. The print output data P1 of the first page shown in Fig. 7A, which is generated based on the drawing data from the DFE 102, is written to the first page buffer memory 505, and the print output data P2 of the next page (the second page) is written to the second page buffer memory 506.

The image forming unit 307 forms an image based on the print output data P1 read from the first page buffer memory 505 as shown in FIG. 7B in accordance with the printing order for print output (image formation). When reading of the print output data P1 from the first page buffer memory 505 is completed, the DFE 102 transfers the drawing data of the print output data P3 to the image processing unit 306. The image processing unit 306 converts the drawing data into print output data P3 and writes it to the first page buffer 505 as shown in FIG. 7B.

When the print image corresponding to the print output data P1 is output from the image forming unit 307, reading of the print output data P2 for the second page starts from the second page buffer memory 506 as shown in FIG. 7(c). During continuous printing, the print data is continuously transferred to the image forming unit 307 while switching between write control and read control for each page buffer memory 505, 506 in this manner.

(Transfer Abnormality)
Next, the operation when a transfer abnormality occurs will be described. A transfer abnormality of the print output data is determined at the timing of completion of reading from each page buffer memory 505, 506 and completion of writing of the next page. In Fig. 7, an example will be described in which data transfer for the third page is completed normally, but a delay occurs in the data transfer for the fourth page, causing an abnormality to be detected.

When reading of print output data P1 from the first page buffer memory 505 is completed, writing of print output data P3 begins to the first page buffer 505. While the print output data P3 is being written, print output data P2 is read from the second page buffer memory 506 as the second page of print output and output to the image forming device 307.

When the reading of the print output data P2 from the second page buffer memory 506 is completed, a second read completion detection notification is supplied to the image transfer monitoring unit 509 as shown in FIG. 7(c). If a first write completion detection notification indicating the writing of the print output data P3 to the first page buffer memory 505 is generated before this second read completion detection notification is supplied to the image transfer monitoring unit 509, the image transfer monitoring unit 509 determines that the operation is normal.

In response to this, after the reading of the print output data P2 from the second page buffer memory 506 is completed, while the print output data P3 is being printed out by the image forming unit 307, the print output data P4 shown in FIG. 7(a) is written to the free second page buffer memory 506.

Here, if the transfer of drawing data from the DFE 102 or the image processing in the print output data generation unit 503 is delayed, the completion of writing the print output data P4 to the second page buffer 506 will also be delayed, as shown in FIG. 7(c) and FIG. 7(d). When the image forming unit 307 completes the printing of the print output data P3 and completes the reading of the first page buffer memory 505, a first read completion detection notification indicating this is supplied from the output unit 504 to the image transfer monitoring unit 509. In the example of FIG. 7, at the time when the first read completion detection notification is supplied to the image transfer monitoring unit 509, a second write completion detection notification indicating that the writing of the print output data P4 is completed has not been supplied to the image transfer monitoring unit 509. In this case, the image transfer monitoring unit 509 determines that a delay has occurred in the preparation of the print output data, as shown in FIG. 7(e).

When the image transfer monitoring unit 509 detects such a transfer abnormality, the transfer abnormality notification unit 511 supplies an instruction to interrupt the print process to the image forming unit 307. This stops the printing of the print output data P4 and the image formation after the print output data P4. The image forming unit 307 specifies a different discharge destination (discharge outlet 406-1 or discharge outlet 406-2) from the normal print results for sheets of paper for which printing on only one side has been completed despite double-sided printing being specified, and sheets of paper that have been fed into the transport path and cannot be returned to the paper feed tray, and separates them from the normal print results. In addition, the print processing order determination unit 501 supplies interruption information indicating the pages for which normal printing has been completed and the pages for which processing has been separated due to the abnormality determination to the retransmission processing determination unit 520 of the DEF 102.

Note that when the print job processing is complete and the transfer of the drawing data is finished, there is no generation of print output data for the next page, so a false detection may occur after the final page is printed. For this reason, the transfer status monitoring unit 510 determines whether writing has been completed for the page for which a print request has been notified.

Figure 8 is a flowchart showing the flow of the write/read operations for each of the page buffer memories 505 and 506, and the operation of determining whether a transfer error has occurred. Each process in this flowchart is executed by the CPU 301 controlling the image processing unit 306 and the image forming unit 307, etc., based on the image formation program stored in a storage unit such as the ROM 302 provided in the image forming device 103.

In the flowchart of FIG. 8, in step S1, the output control unit 507 starts transferring print output data to the image forming unit 307. When the transfer of the print output data starts, the transfer status monitoring unit 510 determines whether or not the reading of the print output data from the first page buffer memory 505 (or the second page buffer memory 506) is completed based on the first read completion detection notification (or the second read completion detection notification) supplied from the output unit 504 (step S2).

When it is determined that the reading of the print output data from the first page buffer memory 505 (or the second page buffer memory 506) is complete, the print processing order determination unit 501 determines whether or not there is a print request for the next page based on the print request from the DEF 102 (step S3). If there is no print request for the next page (step S3: No), all the processing in the flowchart of FIG. 8 is terminated.

On the other hand, if there is a request to print the next page (step S3: Yes), the transfer status monitoring unit 510 determines whether the page buffer memory from which the print output data is read is the first page buffer memory 505 (step S4).

If the page buffer memory from which the print output data is read is not the first page buffer memory 505 (step S4: No), the process proceeds to step S8, where the transfer status monitoring unit 510 determines whether writing of the next page of print output data to the first page buffer memory 505 is complete based on whether a first write completion detection notification has been supplied (step S8).

If the writing of the print output data of the next page to the first page buffer memory 505 is completed (step S8: Yes), the output unit 504 controls to switch the page buffer memory from which data is read to the first page buffer memory 506 (step S9). This causes the process to return to step S1, and the print output data of the next page written in the first page buffer memory 506 is read and supplied to the image forming unit 307.

On the other hand, if the data is not being read from the first page buffer memory 505 (step S4: No), it is being read from the second page buffer memory 506. At this time, if the writing of the print output data for the next page to the free first page buffer memory 505 has not been completed (step S8: No), this means that a delay in writing to the first page buffer memory 505 has occurred.

The transfer status monitoring unit 510 therefore supplies an error notification indicating that a delay has occurred in receiving the print output data to the transfer abnormality notification unit 511 (step S6). When this error notification is supplied, the transfer abnormality notification unit 511 instructs the image forming unit 307 to suspend printing. This causes the printing to be cancelled (step S7).

On the other hand, if it is determined in step S4 that the print output data is read from the first page buffer memory 505 (step S4: Yes), the process proceeds to step S5. In step S5, the transfer status monitoring unit 510 determines whether writing of the next page of print output data to the second page buffer memory 506 is complete based on whether a second write completion detection notification has been provided.

If the writing of the print output data of the next page to the second page buffer memory 506 is completed (step S5: Yes), the output unit 504 controls to switch the page buffer memory from which data is read to the second page buffer memory 506 (step S9). This causes the process to return to step S1, and the print output data of the next page read from the second page buffer memory 506 is transferred to the image forming unit 307.

On the other hand, when the print output data is read from the first page buffer memory 505 (step S4: Yes), if the writing of the print output data of the next page to the second page buffer memory 506 is not completed (step S5: No), this means that there is a delay in writing the print output data of the next page to the second page buffer memory 506. Therefore, the transfer status monitoring unit 510 supplies an error notification indicating that there is a delay in receiving the print output data to the transfer abnormality notification unit 511 (step S6). When this error notification is supplied, the transfer abnormality notification unit 511 instructs the image forming unit 307 to suspend printing. This causes the printing to be canceled (step S7).

(Print stop operation and print restart operation)
Next, the operation from the printing stop operation due to the error notification to the printing restart will be described with reference to the flowchart in Fig. 11. Each process in the flowchart in Fig. 11 is executed by the CPU 301 controlling the image processing unit 306, the image forming unit 307, etc. based on the image forming program stored in a storage unit such as the ROM 302 provided in the image forming apparatus 103.

In the flowchart of FIG. 11, when the continuation of the print process is selected, if the print output data is not prepared in time and the print operation is interrupted (step S21: transfer error detected), the client PC 101, DFE 102, and image forming device 103 perform a print cancellation process based on the interruption information (step S22).

When the print cancellation process is completed (step S23: Yes) and the user selects the automatic print restart process via the client PC (step S24: Yes), the client PC 101 stores print restart information, including page information for pages that have been successfully printed, in a storage unit such as ROM, RAM, or HDD (step S25).

Next, the client PC 101, the DFE 102, and the image forming device 103 each execute a self-diagnosis after the print cancellation process based on the interruption information (step S26). The contents of the self-diagnosis are the contents executed when the power of each unit is turned on, or operations equivalent thereto, and are inspection contents that can guarantee the operation of the units.

If the results of such self-diagnosis indicate that the printing process can continue (step S27: Yes, step S28: Yes), the client PC 101 and the DFE 102 resume the printing operation following the normal printing result based on the print resumption information, and continue the printing process (step S29).

In addition, the client PC 101 and the DFE 102 display information indicating that printing has been interrupted and resumed, the print job where the interruption occurred, and information on the page on which the interruption occurred on the screen of the client PC 101, the DFE 102, or the operation panel of the image forming device 103 (step S30). This notification of the interruption/restart location information allows the user to check the print results later.

On the other hand, if the self-diagnosis determines that it is difficult to resume printing (step S28: No), the client PC 101, the DFE 102, and the image forming device 103 perform a hardware reset process (initialization process) (steps S31 and S32). This allows the client PC 101, the DFE 102, and the image forming device 103 to perform initialization without turning the power on and off, and to attempt to resolve the error state.

When a hardware reset process is performed, during the device start-up process after the reset, it is checked whether print resume information is stored in the memory unit (steps S33 and S34), and if print resume information is stored in the memory unit (step S34: Yes), the printing operation following normal printing is resumed to continue the printing process (step S29).

On the other hand, if the print resume information is not stored in the memory unit (step S34: No), the user is notified of the print interruption via the display unit of the client PC 101 or the operation panel of the image forming unit 103 (step S35).

In this way, the printing system of the first embodiment allows the user to continue printing without having to select whether to resume the printing process. This reduces downtime of the printing system.

(Effects of the First Embodiment)
As is clear from the above description, in the printing system of the first embodiment, the image forming unit 307 does not determine whether the print output data will be ready in time when the print process is executed, but the image processing unit 306 determines this in advance at the upstream stage when the print output data is transferred. Specifically, the transfer status monitoring unit 510 monitors the write status and read status of each page buffer memory 505, 506 based on the buffer control status notification supplied from the output unit. Then, if the transfer status monitoring unit 510 determines that the print output will not be ready in time for the image forming unit 307's print output timing, the transfer abnormality notification unit 511 instructs the image forming unit 307 to interrupt printing.

When the image forming unit 307 receives an interrupt instruction, it stops the print output operation and stops the feeding of new paper from the paper feed tray 400. At the same time, paper for which normal printing has been completed is discharged to a paper output port for paper for which normal printing has been completed, and paper for incomplete pages, such as pages with missing images due to the stop of the print output operation and pages where printing has been completed only on one side of a double-sided print job, is discharged to a paper output port for these incomplete pages.

The image processing unit 306 also notifies the client PC via the DEF 102 of the information about the page that has been successfully printed as interruption information. The client PC 101 notifies the user of the interruption of printing via a display unit or the like. When the user instructs the printing process to be resumed, the client PC 101 resends the print job information from the page following the page that was successfully printed before the interruption, and the printing process is resumed.

This helps prevent abnormal images from being output and reduces downtime of the printing system.

[Second embodiment]
Next, a printing system according to a second embodiment will be described. In this second embodiment, the transfer status monitoring unit 510 shown in FIG. 6 judges a transfer abnormality of print output data based on the timing of starting writing to an empty page buffer and the timing of starting reading from a page buffer in which writing is not being performed. Note that apart from this point, the configuration and operation are the same as those of the first embodiment described above. Therefore, only the differences between the two will be described below, and overlapping explanations will be omitted.

Next, the write/read control for each page buffer memory 505, 506 will be described with reference to FIG. 9. FIG. 9 shows an example in which data transfer is completed normally on the third page, but a delay occurs in data transfer on the fourth page, causing an abnormality to be detected.

First, as shown in FIG. 9(a) and FIG. 9(b), print output data P1 is read from the first page buffer memory 505, and print output data P3 can be written to the first page buffer 505. After printing of the print output data P1 is completed and the inter-paper transport time has elapsed, the print output data P2 is transferred from the second page buffer memory 506 to the image forming device 307 as the print output of the second page. As a result, a second read start detection notification indicating the start of reading of the print output data P2 from the second page buffer memory 506 is supplied from the output unit 504 to the image transfer monitoring unit 509 as shown in FIG. 9(c).

The writing of print output data P3 to the first page buffer memory 505 can start earlier than the start of output of print output data P2 by the paper transport time. Therefore, if a first write start detection notification of print output data P3 has been supplied to the first page buffer memory 505 at the time a second read start detection notification has been supplied to the second page buffer memory 506, the transfer status monitoring unit 510 determines that the transfer operation of the next page has started normally, as shown in FIG. 9(d).

In response to this, as shown in Figures 9(b) and 9(c), the transfer status monitoring unit 510 determines whether writing of the print output data of the next page, print output data P4, to the second page buffer memory 506 has started at the time when reading of print output data P3 from the first page buffer memory 505 has started.

As shown in Figures 9(b) and 9(c), at the time when the first read start detection notification is provided indicating that reading of print output data P3 has started from the first page buffer memory 505, the second write start detection notification indicating the start of writing of print output data P4 to the second page buffer memory 506 has not occurred. Therefore, the transfer status monitoring unit 510 determines that there is a problem with the preparation of print output data P4, as shown in Figure 9(d). As a result, the transfer abnormality notification unit 511 notifies the image forming unit 307 of an interrupt instruction, and the printing of print output data P4 and image formation after print output data P4 are stopped.

The transfer status monitoring unit 510 judges when to start reading the print output data at the timing when reading starts from each page buffer memory 505, 506. However, if a transfer buffer memory is provided on the transport path from each page buffer memory 505, 506 to the output control unit 507 and the image forming unit 307, the read operation from the page buffer memory may start earlier than the timing when the image forming unit 307 starts actual writing. For this reason, the transfer status monitoring unit 510 may make a judgment under a delayed detection condition so as to detect that the main scan's worth of image data or the main scan's x the specified number of lines' worth of image data has been read, based on the information on the print image size notified by the print request from the DEF 102.

Figure 10 is a flowchart showing the flow of the write/read operations for each page buffer memory 505, 506 and the operation of determining transfer abnormalities in the printing system of the second embodiment. Each process in the flowchart of Figure 10 is executed by the CPU 301 controlling the image processing unit 306 and the image forming unit 307, etc., based on the image formation program stored in a storage unit such as the ROM 302 provided in the image forming device 103.

In the flowchart of FIG. 10, as described above, when a request to print the next page occurs in step S3 (step S3: Yes) and processing proceeds to step S4, the transfer status monitoring unit 510 determines whether or not reading of print output data has started from the first page buffer memory 505 based on the first read start detection notification.

If it is determined that reading of print output data from the first page buffer memory 505 has started (step S4: Yes), the process proceeds to step S5. In step S5, the transfer status monitoring unit 510 determines whether writing of print output data to the second page buffer memory 506 has started based on the second write start detection notification.

Even though reading from the first page buffer memory 505 has started (step S4: Yes), writing of the next page of print output data to the second page buffer memory 506 has not started (step S5: No), which means that a delay error in the print output data has occurred. Therefore, the transfer status monitoring unit 510 notifies the transfer error notification unit 511 of the delay error in the print output data (step S6). As a result, the transfer error notification unit 511 notifies the image forming unit 307 of an interrupt instruction, and the print cancellation process is performed as described above (step S7).

On the other hand, if reading from the first page buffer memory 505 has started (step S4: Yes) and writing of the next page of print output data to the second page buffer memory 506 has already started (step S5: Yes), processing proceeds to step S11.

In step S11, the transfer status monitoring unit 510 determines whether writing of the print output data of the next page to the second page buffer memory 506 is complete based on the second write completion detection notification supplied from the output unit 504. The output unit 504 waits for the writing of the print output data of the next page to be completed to the second page buffer memory 506 (step S11: Yes), and then controls to switch the page buffer memory to be written to to the first page buffer memory 505.

On the other hand, if reading from the first page buffer memory 505 has not started (step S4: No) and writing of the next page of print output data to the first page buffer memory 505 has not started (step S8: No), this means that a delay error in the print output data has occurred. Therefore, the transfer status monitoring unit 510 notifies the transfer error notification unit 511 of the delay error in the print output data (step S6). As a result, the transfer error notification unit 511 notifies the image forming unit 307 of an interrupt instruction, and the print cancellation process is performed as described above (step S7).

On the other hand, if reading from the first page buffer memory 505 has not started (step S4: No) and writing of the next page of print output data to the first page buffer memory 505 has already started (step S8: Yes), the process proceeds to step S11.

In step S11, the transfer status monitoring unit 510 determines whether or not writing of the print output data of the next page to the first page buffer memory 505 is complete based on the first write completion detection notification supplied from the output unit 504. The output unit 504 waits for the writing of the print output data of the next page to be completed to the first page buffer memory 505 (step S11: Yes), and then controls switching of the page buffer memory to be written to the second page buffer memory 506.

This allows for the same effect as in the first embodiment described above.

Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. The novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and modifications of the embodiments are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims.

101 Client PC
102 Information processing device (DEF)
103 Image forming apparatus 306 Image processing unit 307 Image forming unit 400 Paper feed tray 406-1 Paper discharge port 406-2 Paper discharge port 501 Print processing order determination unit 503 Print output data generation unit 504 Output unit 505 First page buffer memory 506 Second page buffer memory 507 Output control unit 509 Image transfer monitoring unit 510 Transfer status monitoring unit 511 Transfer abnormality notification unit 520 Retransmission processing determination unit

JP 2008-044172 A

Claims (6)

An image forming apparatus that sequentially writes and reads print information to and from a plurality of storage units including a first storage unit and a second storage unit, and supplies the print information read from each of the storage units to an image forming unit to print on paper,
a delay detection unit that detects a delay in starting to write the print information to each of the storage units;
a control unit that, when the delay detection unit detects a delay in starting writing, ejects the paper that has already been fed and controls the image forming unit to stop feeding the paper from the paper feed unit, thereby interrupting the print process;
having
The image forming apparatus is characterized in that the delay detection unit detects a delay in the start of writing when the start of writing to the second memory unit has not been notified at the time when the start of reading from the first memory unit is notified. the delay detection unit, after detecting a delay in starting to write the print information to each of the storage units, determines whether or not the delay in starting to write the print information to each of the storage units has been resolved;
2. The image forming apparatus according to claim 1, wherein the control unit controls the image forming unit to resume printing when the delay detection unit determines that a delay in starting to write the print information to each of the memory units has been resolved. The image forming apparatus according to claim 2 , wherein the control unit controls the image forming unit so as to resume printing from a page next to a page for which printing has been completed. the control unit controls the image forming unit so that the paper on which printing has not been completed is discharged from a paper discharge outlet different from a paper discharge outlet for the paper on which printing has been completed;
4. The image forming apparatus according to claim 1, wherein: 1. An image forming method for an image forming apparatus, comprising: sequentially writing and reading print information to and from a plurality of storage units including a first storage unit and a second storage unit; and supplying the print information read from each of the storage units to an image forming unit for printing on paper, the method comprising:
a delay detection step in which a delay detection unit detects a delay in starting writing of the print information to each of the storage units;
a control step of controlling the image forming unit to eject the paper that has already been fed and to stop feeding the paper from the paper feed unit, thereby interrupting the printing process, when the delay detection unit detects a delay in starting writing;
having
The image forming control method is characterized in that the delay detection step detects a delay in the start of writing when the start of writing to the second memory unit has not been notified at the time when the start of reading from the first memory unit is notified. An image forming program for an image forming apparatus that sequentially writes and reads print information to and from a plurality of storage units including a first storage unit and a second storage unit, and supplies the print information read from each of the storage units to an image forming unit for printing on paper,
Computer,
a delay detection unit that detects a delay in starting to write the print information to each of the storage units;
when the delay detection unit detects a delay in starting writing, the image forming unit controls the image forming unit to eject the paper that has already been fed and to stop feeding the paper from the paper feed unit, thereby functioning as a control unit that interrupts the print process;
The image forming program is characterized in that the delay detection unit detects a delay in the start of writing when the start of writing to the second memory unit has not been notified at the time when the start of reading from the first memory unit is notified.

Images