JP2006347100A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that overwriting the storage area of printed printing data with data erasing data to maintain confidentiality when the printing data input from outside is to be stored in a magnetic storage device for example delays the printing of subsequent printing data because the image forming device performs the erasing while the device is waiting so as not to hinder printing. <P>SOLUTION: A printing data erasing section 17 overwrites the storage area of printing data read by an image conversion section 16 with fixed data in parallel with image conversion by the image conversion section and overwrites a storage area overwritten with the fixed data with random number data generated in a random number generation section 18 after printing ends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a processing function for maintaining confidentiality of a printed document.

  After the image formation is completed, there is a case in which the printed data temporarily stored in the storage unit in the process is overwritten with another data, thereby making it impossible to restore the printed data after the erasing process. In this case, when a magnetic storage device such as a hard disk is used as the storage unit, there is a possibility that the original data may be restored by one overwrite, so the overwrite is performed a plurality of times. In addition, the erasing process is performed when the image forming apparatus is in a standby state so as not to interfere with other printing processes.

  In addition, in order to maintain the confidentiality of the printed document, it has a printer having a discharge tray for discharging the normal printed matter and a lock box for discharging the confidential printed matter, and is locked from the terminal device for creating the printed document. There has been a printer system in which a printed matter is discharged to a lock box when a code designating discharge to a box is attached (for example, see Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-227216 (first page, FIG. 1)

  In the case where it is impossible to restore the printed data stored in the magnetic storage device such as a hard disk after the erasing process, when printing data that needs to maintain the confidentiality of the printed document is received one after another, There is a problem in that the storage device is filled with printed data to be erased, and the print processing of the subsequent print data is waited for a long time until the erase processing of the printed data in the storage unit is completed. Further, in the printer system disclosed in Patent Document 1, there is a possibility that the printed data remaining in the storage unit in the system may be restored even if the printed document is kept secret.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that solves the above-mentioned problems, maintains the confidentiality of printed data, and at the same time smoothly performs print processing of sequentially received print data.

The image forming apparatus of the present invention includes:
Print data storage means having a print data storage area for storing print data, print data erasure means for erasing the print data by overwriting different types of erasure write data in the print data storage area, and the print data Print processing means for reading the print data from the storage area and performing print processing;
The print data erasing unit performs a primary overwriting of the erasure data on the storage area of the print data read by the print processing unit in parallel with the print processing of the print processing unit. The second overwriting of the erasing data is executed after the printing process of the print processing unit is completed.

Furthermore, another image forming apparatus of the present invention is
Print data storage means having a print data storage area for storing print data, and the print data storage area by overwriting the write data for erasure that requires computation and the write data for erasure that does not require computation Print data erasing means for erasing data; and print processing means for reading the print data from the print data storage area and performing print processing;
The print data erasure unit overwrites the print data storage area read by the print processing unit with erasure write data that does not require at least the calculation in parallel with the print processing of the print processing unit. Then, after the print processing of the print processing means is completed, the write data for erasure that requires the calculation is overwritten in the storage area in which the write data for erasure that does not require the calculation is overwritten.

  According to the image forming apparatus of the present invention, it is possible to shorten the time for erasing the printed data after the printing process of the print data.

Embodiment 1 FIG.
FIG. 1 is a block diagram schematically showing a main configuration of a printing system according to a first embodiment having an image forming apparatus of the present invention.

  As shown in FIG. 1, the printing system 1 includes an image forming apparatus 10, a printing unit 51, a network 52, and an information processing apparatus 53. The image forming apparatus 10 includes a CPU 11, a RAM 12, a print data management unit 13, and a printing. A control unit 14, a communication control unit 15, an image conversion unit 16, a print data erasing unit 17, a random number generation unit 18, a hard disk 19, and a common bus 20 that connects them are provided.

  The CPU 11 controls the entire apparatus by executing a control program of the image forming apparatus 10. For example, the communication control unit 15, the image conversion unit 16, the print control unit 14, the print data management unit 13, the print data erasing unit 17, a random number The generation unit 18 is activated. The RAM 12 is a volatile memory used when the CPU 11 executes the control program, and stores, for example, print data 21 used by the image conversion unit 16 at the time of image conversion and image data generated as a result of the image conversion. The communication control unit 15 transmits / receives information to / from the information processing apparatus 53 via the network 52. The image forming apparatus 10 receives the print data 21 from the information processing apparatus 53 via the communication control unit 15. The hard disk 19 has a print data storage area and stores print data 21 and a print data management list 22.

  Here, the print data 21 and the print data management list 22 will be described. The print data 21 is a set of image drawing commands generated by the information processing apparatus 53, received by the communication control unit 15, and stored in the hard disk 19. In this embodiment, a description will be given assuming that one print data is stored in the print data storage area in the hard disk 19 as one file. Examples of the image drawing command include PCL (Printer Control Language), POSTSCRIPT, and the like, but are not particularly limited. In the following description, for convenience of explanation, print data before reading for image conversion is referred to as pre-read print data among print data stored in the hard disk 19. The print data is referred to as read print data, and the term “print data” refers to both of them.

  FIG. 2 is a diagram for explaining the print data management list 22. As shown in the figure, the print data management list 22 stores the print data file name, the print data size, and the print processing status of the print data corresponding to each print data, its print data size, and the processing status. to manage.

  The image conversion unit 16 is a part that reads the print data stored in the hard disk 19 during the printing process and converts it into image data that can be printed by the printing unit 51. The image conversion here is performed by analyzing the image drawing command using the CPU 11 and performing operations such as wavelet transform and discrete cosine transform. Therefore, during the image conversion process, the CPU 11 cannot execute another process with a high load factor.

  The print control unit 14 is a part that controls the printing unit 51 during printing processing to print out. The printing unit 51 is a mechanism unit that prints the image data generated by the image conversion unit 16 on a medium. The print data management unit 13 is a part that manages the print data 21 stored in the hard disk 19. The print data 21 is managed when the communication control unit 15 receives print data, when the print control unit 14 completes printing, and when the print data erasing unit 17 completes deletion of printed data. This is done by updating the data management list 22.

  As a result, the print data erasure unit 17 overwrites another print data for erasure in the print data storage area stored in the print data storage area in the hard disk 19 so that the data cannot be restored after the erasure process. It is a part to do. In the present embodiment, when erasing the printed data, the fixed data “0” is written in the area in which the read print data is stored when read for printing, and the print processing is completed. Then, the random number data generated by the random number generator 18 is written.

  However, the value of the data to be overwritten and the number of overwriting are not limited to the present embodiment. The random number generator 18 generates random data to be overwritten when the printed data is deleted. In this embodiment, a hash operation is used to generate random number data, but the random number data generation algorithm is not particularly limited. However, regardless of which random number data generation algorithm is used, computation for a certain period of time using the CPU 11 is required, and during that time, the CPU 11 cannot execute other processing with a high load factor.

  The common bus 20 is a bus that connects the components. The network 52 is a communication path that connects the information processing apparatus 52 and the image forming apparatus 10. In the present embodiment, the network 52 is used as a connection method between the information processing apparatus 52 and the image forming apparatus 10, but the present invention is not limited to this, and a Centronics, USB, wireless LAN, or the like may be used. The information processing device 53 is an external device that generates the print data 21 and transmits the generated print data 21 to the image forming apparatus 10. Examples of the information processing device 53 include a personal computer and a workstation, but are particularly limited. Not what you want.

In the above configuration, the operation of the printing system 1 will be described.
FIG. 3 is a flowchart showing a flow of print data reception processing performed by the image forming apparatus 10. The print data reception process of the image forming apparatus 10 will be described below with reference to this flowchart.

  When receiving the print data from the information processing apparatus 53, the communication control unit 15 detects this and notifies the print data management unit 13 of this detection (step ST101). The print data management unit 13 checks whether or not an erase priority mode, which will be described later, is set (step ST102). If the erase priority mode is set, the print data management unit 13 is in a standby state until the erase priority mode is canceled. . The erasure priority mode is a mode that is set based on a predetermined determination as will be described later in order to temporarily stop the print data reception process and preferentially erase the printed data in the hard disk. . The erasure priority mode is set for the purpose of preventing the hard disk 19 from being filled with printed data and storing data other than the print data, such as font data and macros.

  If the erasure priority mode is not set, the print data management unit 13 stores the print data 21 detected by the communication control unit 15 as a print file in the print data storage area in the hard disk 19 (step S103), and the received print The file size of the data is measured, and the file name and processing state (unprocessed) are registered together in the print data management list 112 (step S104). For example, here, as shown in the first column of the list of FIG. 2, the print data file name (print data 1), the print data size (204800 bytes), and the processing state (unprocessed) are registered.

  FIG. 4 is a flowchart showing the flow of printing processing performed by the image forming apparatus 10. The operation of the printing process of the image forming apparatus 10 will be described below with reference to this flowchart.

  The image conversion unit 16 reads the print data from the hard disk 19 in order to perform the image conversion process (step S201). After the read process is completed, the image conversion unit 16 notifies the print data erasing unit 17 of the file name of the read print data. An overwriting process of the fixed data (fixed value “0”) to the storage area of the read print data in 19 is instructed (step S202). The fixed data overwriting process by the print data erasing unit 17 will be described later using another flowchart.

  The image conversion unit 16 converts the print data read from the hard disk 19 using the CPU 11 into printable image data (step S203), and the print control unit 14 prints the image data generated by the image conversion unit 16. The printing unit 51 prints the received image data under the control of the print control unit 14 (step S204). Note that the printing process performed by the image forming apparatus 10 is a process until the image data generated by the image conversion unit 16 is output to the printing unit 51.

  The print data management unit 13 changes the print data management list 22 so that the processing state of the print data stored in the hard disk 19 corresponding to the print processed image data is “processed” (step S205). The total data size of the print data “processed” in the print data management list 22 is confirmed (step S206).

  FIG. 5 is a flowchart showing the flow of the process for checking the total printed data size performed in step S206 in FIG. The confirmation processing operation performed by the image forming apparatus 10 will be described below with reference to this flowchart.

  The print data management unit 13 calculates the total data size of the print data (print data that has been printed) in the print management data list 22 (see FIG. 2) whose processing status is “processed” (see FIG. 2). Step S301). Then, it is determined whether or not the calculated total size of the “processed” print data exceeds a predetermined processed data upper limit value (step S302). The processed data upper limit value may be given a fixed value in advance or may be set by the user, but here, a fixed value is set in advance.

  Here, when it is determined that the calculated total size is equal to or smaller than the predetermined upper limit value, it is further checked whether or not the erase priority mode is set (step S303). If the erase priority mode is set, the erase priority is set. The mode designation is canceled and the process is terminated. If the deletion priority mode is not set, the process is terminated as it is. On the other hand, if it is determined in step S302 that the total size has exceeded a predetermined upper limit value, an erase priority mode is set (step S305). When the erasure priority mode is set, as described with reference to the flowchart of the print data reception process shown in FIG. 3, print data reception is stopped during this period.

  FIG. 6 is a flowchart of fixed data overwrite processing performed by the image forming apparatus 10. The operation of the fixed data overwriting process of the image forming apparatus 10 will be described below with reference to this flowchart.

  This process is performed in parallel with the image conversion process by the image conversion unit 16. The print data erasure unit 17 receives the file name of the read print data read from the hard disk 19 by the image conversion unit 16 notified from the image conversion unit 16 (by the process of step S202 in the flowchart of the print process in FIG. 4). Then, the fixed data “0” is overwritten in the area where the read print data is stored in the hard disk 19 (step S401). The process of overwriting 0 in the area of the hard disk where file data is stored is performed using DMA (Direct Memory Access), so that the CPU 11 is hardly loaded. Therefore, it can be executed in parallel with the image conversion processing by the image conversion unit 16.

  FIG. 7 is a flowchart showing a flow of random number data overwriting processing performed by the image forming apparatus 10. The operation of the random number data overwriting process of the image forming apparatus 10 will be described below with reference to this flowchart.

  This process is repeatedly executed while the image forming apparatus 10 is in operation. Note that the operating state here is a state in which the image forming apparatus can be used, receiving print data, converting an image, printing processing, or waiting to receive the next print data. It shall mean each state.

  The print data erasure unit 17 inquires the print data management unit 13 about the processing state of the print data 21 stored in the hard disk 19, and the print data management unit 13 confirms the print data management unit 13 in response to the inquiry. Information on the processing state of each print data held in the list 22 (see FIG. 2) is obtained (step S501). The print data erasure unit 17 obtains this information and determines whether or not pre-print data (print data whose processing status in the print data management list 22 is “unprocessed”) exists in the hard disk 19 (step S502). ). When it is determined that the print data exists, the print data erasure unit 17 determines that another processing unit is executing or is scheduled to execute a process with a high load on the CPU 11, and ends the process without doing anything.

  On the other hand, if it is determined in step S502 that the pre-print data does not exist in the hard disk 19, further printed data (print data whose processing status in the print data management list 22 is “processed”) exists in the hard disk 19. It is determined whether or not (step S503). If it is determined that it does not exist, the print data erasure unit 17 ends this process without doing anything.

  On the other hand, if it is determined in step S503 that printed data exists in the hard disk 19, the print data erasure unit 17 instructs the random number generation unit 18 to generate random number data in order to overwrite the printed data. The random number generation unit 18 generates random number data using the CPU 11 and outputs the generated random number data to the print data deletion unit 17 (step S504). The print data erasing unit 17 overwrites the generated random number data in the area where the printed data in the hard disk is stored (the fixed data is already overwritten in this area) (step S505).

  Further, the print data erasing unit 17 deletes the print data file for which the overwriting of the random number data has been completed, and deletes the management information of the print data from the print data management list 22 (step S506). When the print data is deleted from the print data management list 22, the print data management unit 13 re-executes the confirmation process for the total size of the printed data described with reference to the flowchart shown in FIG. The mode is changed (step S507).

  Of the print data storage area in the hard disk 19, the area where the fixed data and the random number data are overwritten as described above is determined to be impossible to restore the print data stored in this area. It is also possible to add processing for releasing the area.

  FIG. 8 is a time chart showing an operation example of the image forming apparatus 10 that operates based on the flowcharts described above. Incidentally, as a guide for knowing the operation status of the CPU 11 and the hard disk 22 during this period, their utilization rates are shown at two levels at the same time. In the time chart, the same process numbers (1) to (6) are assigned to the positions indicating the timings at which the following (Process 1) to (Process 6) are performed.

At time t _1, the communication control unit 15 receives the print data (A) from the information processing apparatus 53, the printing according to the flow of the print data receiving process shown in FIG. 3 described above, print data [A] received in the hard disk 19 The file size and the processing state of the print data [A] stored together with the file name are stored in the print data list 22 (process 1). At this time, it is assumed that the erase priority mode is not set. When then becomes time t _2, the following flow of the printing process shown in FIG. 4 described above, the printing process of the print data stored [A] is started. That the image conversion unit 16 reads out the print data [A] from the hard disk 19 (step 2), the image conversion of the print data with the read At time t ₃ [A] is started. In parallel with this image conversion, the fixed data “0” is overwritten in the storage area of the read print data [A] in the hard disk 19 in accordance with the flow of the fixed data overwrite process shown in FIG. 6 (process 3).

At time t _5, the print control unit 14 performs and controls the printing unit 51, printing of the image data generated by the image conversion by the image conversion unit 16 is started. Then, the print data management unit 13 changes the print data management list 22 so that the processing state of the print data [A] printed out is “processed”, and the print data 11 in the print data management list 22 is changed. Then, the total print data size whose processing status has been printed is confirmed (processing 4).

On the other hand, at time t ₃ , the image forming apparatus 10 receives print data [B] from the information processing apparatus 53. At this time, since the erasure priority mode is not set, the image forming apparatus 10 stores the received print data [B] as a print file in the hard disk 19, and thereafter performs the same print processing as the print data [A] described above. It is executed in parallel with the processing of the print data [A]. That is, execute the processing 1 for the print data from the time t ₃ (B), it is from time t ₄ to execute the process 2 for the print data (B), the print data from the time t ₆ [B The process 3 is executed for the print data [B] from time ₇ .

As described above, the image forming apparatus 10 repeatedly executes the random number data overwriting process according to the flow shown in FIG. 7, and further, at time t ₈ , the processing state of the print data [B] printed out is changed to “Processing”. The print data management list 22 is changed to “complete”. For this reason, there are no “unprocessed” files in the print data management list 22, and there are two “processed” files. By the processing in step S 504 in the flowchart, the printed data is displayed at time t _9. to generate a random number for overwriting the [a] (process 5), the subsequent time t _10, the region printed data generated random number data to the hard disk (a) has been stored (in this area The fixed data is already overwritten), and the file of the printed data [A] is deleted and deleted from the print data management list 22 (process 6).

The random number data overwriting process (process 5, 6), after being executed for print data at time _{t 9} and time _{t 10} [A], the print data at time _{t 11} and time _{t 12} [B] Is also executed.

During this time, the CPU 11 is mainly used at the time of image conversion from time t ₃ or time t ₆ and at the time of random number generation processing from time t ₉ or time t ₁₁ , and at the time of data processing for the hard disk 19 using DMA. Not used. Therefore, it is possible to execute the write process to the time t ₃ or time t of the image conversion processing at the same time as the fixed data from ₆ Hard 19. Furthermore, in the process of processing the print data [A] and the print data [B] in parallel, it is possible to simultaneously access the print data to the hard disk 19. Incidentally, by multiplying the time t ₅ from the time t ₃ when applicable to this situation, utilization of the hard disk 19 is increased. Further, as described above, the image forming apparatus 10 takes into consideration that the image processing by the CPU 11 and the random number generation processing do not overlap by step S502 of the random number data overwrite processing shown in FIG.

  In the time chart of FIG. 8, the print processing period T1 is a period from the start of receiving print data [A] to the completion of printing of print data [B], and the print data erasing period T2 is all print data (print data [A], a period from the completion of printing of the printing data [B]) to the completion of writing the random number data of the printing data [B].

  FIG. 9 shows a time chart in the case where the image conversion process and the writing process of the fixed data to the hard disk 19 are not performed simultaneously as a comparative example. In the time chart of FIG. 9, when the same processing as that performed in the time chart of FIG. 8 is performed on the print data [A] and [B], the same processing number is assigned. The detailed description here will be omitted, and different points will be mainly described below.

In this case, the processing 1 from time t ₂₁ to the print data (A), after the process 2 is executed, only the image conversion process is performed from the time t ₂₂ (process 11). In other words, the fixed data “0” is not overwritten in the storage area of the read print data [A] in the hard disk 19 simultaneously with the image conversion process. On the other hand, in the processing for the print data starting from the time t ₂₂ (B), the processing 1, after the process 2 is executed, the process 11 of the image conversion processing only is executed from the time t _23.

After the print processing period T1 from the start of reception of the print data [A] to the completion of printing of the print data [B] ends, the print data deletion period T3 starts here, but this print data deletion period T3 starts at time t ₂₄ starts from the overwriting process (process 12) of the fixed data “0” to the read print data [A] from ₂₄ . After the overwriting process 12 has been completed, further wherein the random number data overwriting process (process 5, 6) is executed, from the subsequent time t _25, the same processing on the print data is now [B] 12,5 , 6 are sequentially executed, and the print data erasing period T3 ends.

  In this comparative example, only the image conversion process is executed in the process 11, and overwriting of the fixed data “0” to the read print data [A] in the hard disk 19 is not executed in parallel. The rate will not rise. Further, in the comparison with the time chart of FIG. 8, since the overwriting process 12 is performed a plurality of times during the print data erasure period T3, the print data erasure period T3 is correspondingly longer than the print data erasure period T2 in the time chart of FIG. become longer.

  As described above, according to the printing system of the first embodiment, the overwrite process at the time of erasing the print data is divided and the fixed data overwrite process is performed in parallel with the image conversion process. Since only the generation and the overwriting process are performed, the time from the completion of printing to the completion of the erasing process of the print data is shortened. Accordingly, the storage unit is not easily filled with printed data, and even when the storage unit is full, the time until the start of processing of the next pre-print data can be shortened.

Embodiment 2. FIG.
FIG. 10 is a block diagram schematically showing a main configuration of a printing system according to the second embodiment having the image forming apparatus of the present invention. This printing system 2 is mainly different from the printing system 1 of the first embodiment shown in FIG. 1 described above in that a random number storage unit 31 is added to the image forming apparatus 30 and the operation accompanying this addition is different. . Accordingly, in this printing system 2, parts that are the same as those in the printing system according to the first embodiment (FIG. 1) are given the same reference numerals, or the drawings are omitted and the description thereof is omitted here. Explain mainly.

  The random number storage unit 31 is a volatile memory connected to the common bus, and temporarily stores the random number data generated by the random number generation unit 18. In the present embodiment, the random number storage unit 31 is described separately from the RAM 12, but the random number storage unit 31 may be provided in the RAM 12.

In the above configuration, the operation of the printing system 2 will be described.
However, the print data reception process, the print process, and the print data size total confirmation process performed by the image forming apparatus 30 are the same as the print data reception process (see FIG. 3) performed by the image forming apparatus 10 according to the first embodiment. This is the same as the print processing (see the flowchart of FIG. 4), the print data size total confirmation process (see the flowchart of FIG. 5), and the description thereof is omitted here.

  FIG. 11 is a flowchart of the overwrite process executed by the image forming apparatus 30 simultaneously with the image data conversion process. The operation of the overwriting process of the image forming apparatus 30 will be described below with reference to this flowchart.

  This process is performed in parallel with the image conversion process by the image conversion unit 16 (equivalent to the process of step S203 in the flow of FIG. 4). The print data erasure unit 17 receives the file name of the read print data read from the hard disk 19 by the image conversion unit 16 notified from the image conversion unit 16 (by the process of step S202 in the flowchart of the print process in FIG. 4). Then, the fixed data “0” is overwritten in the area where the read print data in the hard disk 19 is stored (step S601). The process of overwriting 0 in the area in the hard disk where the file is stored is performed using DMA (Direct Memory Access), and therefore, the CPU 11 is hardly loaded. Therefore, it can be executed in parallel with the image conversion processing by the image conversion unit 16.

  Then, the print data erasure unit 17 checks whether or not random number data larger than the data size of the read print data currently being overwritten is stored in the random number storage unit 31 (step S602). Here, when the size of the stored random number data is larger than the print data size currently being overwritten, the print data erasing unit 17 stores the random number data read from the random number storage unit 31 with the fixed data overwritten. Further overwriting is performed on the area (step S603). Thereafter, the print data file overwritten with the random number data is deleted, and the management information of the print data is deleted from the print data management list 22 (step S604). When the print data is deleted from the print data management list 22, the print data management unit 13 re-executes the confirmation process for the total size of the printed data described with reference to the flowchart shown in FIG. The mode is changed (step S605).

  On the other hand, in step S602, when the size of the random number data stored in the random number storage unit 31 is smaller than the size of the read print data currently being overwritten, this processing ends. In this case, the read-out print data that could not be overwritten with the random number data is overwritten with the random number data after the printing process is completed by the random number data overwriting process described later.

  FIG. 12 is a flowchart showing a flow of random number data overwrite processing performed by the image forming apparatus 30. The operation of the random number data overwriting process of the image forming apparatus 30 will be described below with reference to this flowchart.

  This process is repeatedly executed while the image forming apparatus 30 is in operation. Note that the operating state here is a state in which the image forming apparatus can be used, receiving print data, converting an image, printing processing, or waiting to receive the next print data. It shall mean each state.

  The print data erasure unit 17 inquires the print data management unit 13 about the processing state of the print data 21 stored in the hard disk 19, and the print data management unit 13 confirms the print data management unit 13 in response to the inquiry. Information on the processing state of each print data held in the list 22 (see FIG. 2) is obtained (step S701). The print data erasure unit 17 obtains this information, and determines whether or not pre-print data (print data in which the processing state of the print data management list 22 is “unprocessed”) exists in the hard disk 19 (step S702). ). If it is determined that the print data exists, the print data erasure unit 17 determines that another processing unit is executing or is scheduled to execute a process with a high load on the CPU 11, and ends the process without doing anything.

  On the other hand, if it is determined in step S <b> 702 that pre-print data does not exist in the hard disk 19, print data (print data whose processing status in the print data management list 22 is “processed”) exists in the hard disk 19. It is determined whether or not (step S703).

  When it is determined that the printed data exists in the hard disk 19, the print data erasing unit 17 instructs the random number generation unit 18 to generate random number data to overwrite the printed data. The random number generation unit 18 generates random number data using the CPU 11 and outputs the generated random number data to the print data erasing unit 17 (step S704). The print data erasing unit 17 overwrites the generated random number data in the area where the printed data in the hard disk is stored (the fixed data is already overwritten in this area) (step S705).

  Further, the print data erasure unit 17 deletes the file storing the print data for which random number data has been overwritten, and deletes the management information of the print data from the print data management list 22 (step S706). When the print data is deleted from the print data management list 22, the print data management unit 13 re-executes the confirmation process for the total size of the printed data described with reference to the flowchart shown in FIG. The mode is changed (step S707).

  On the other hand, if it is determined in step S703 that no printed data exists in the hard disk 19, the print data erasing unit 17 determines that the image forming apparatus 30 is on standby. Thereby, the random number generation unit 18 confirms whether or not there is a remaining capacity capable of writing random numbers in the random number storage unit 31 (step S708), and when there is no remaining capacity, that is, when the random number is fully written. Ends the process as it is, and if there is a remaining capacity, that is, if random numbers can be written, random number data is generated, and the generated random number data is stored in the random number storage unit 31 (step S709). In this case, if the random number data of a large size is generated at one time, reception of the next print data is hindered. Therefore, the size of the random number data generated at a time is set to several hundred kilobytes to several megabytes and can be completed in a short time. desirable.

  FIG. 13 is a time chart showing an operation example of the image forming apparatus 30 that operates based on the flowcharts described above. In addition, as a guide for knowing the operation status of the CPU 11 and the hard disk 22 during this period, their utilization rates are shown in two levels. In the time chart of FIG. 13, the same processing numbers are assigned to the print data [A] and [B] when the same processing as that performed in the time chart of FIG. 8 is performed.

In this time chart, generation of random numbers and storage in the random number storage unit 31 are repeated from time t ₃₁ when the image forming apparatus 30 is on standby until random number data is completely written in the random number storage unit 31. At time t ₃₂ that the storage is finished, the communication control unit 15 receives the print data (A) from the information processing apparatus 53 according to the flow of the print data receiving process shown in FIG. 3 described above, print data received (A) Is stored in the hard disk 19 as a print file, and the file size and processing state of the pre-print data [A] stored together with the file name are also stored in the print data list 22 (process 1). Here, an example is shown in which random number data is fully stored in the random number storage unit 31 by executing generation of a random number and storage in the random number storage unit 31 four times. However, the random number storage unit 31 still stores the random number data. there is available residual capacity, even during ongoing production and storage of the random number, if there is an input of print data before at time t _32, the process is interrupted.

When subsequently at time t _33, according to the flow of a printing process shown in FIG. 4 described above, the printing process of the print data stored [A] is started. That the image conversion unit 16 reads out the print data [A] from the hard disk 19 (step 2), the image conversion of the print data with the read at time t ₃₄ [A] is started. In parallel with this image conversion, the flow of the overwriting process shown in FIG. 11 is performed. Here, in step S602 of the flow, it is determined that the size of the random number data stored in the random number storage unit 31 is equal to or larger than the print data size currently being overwritten. Therefore, the read print data [A] read in process 2 from time t ₃₃ is overwritten with fixed data and random numbers in the storage area in the hard disk 19, and the file and print data management list 22 Management information is deleted (process 21).

At time t _36, the print controller 14 performs and controls the printing unit 51, printing of the image data generated by the image conversion by the image conversion unit 16 is started (step 4). Here, since the information of the print data [A] has already been deleted, steps S205 and 206 in the print processing flow shown in FIG. 4 are substantially passed.

On the other hand, at time t ₃₄ , the image forming apparatus 30 receives pre-printing data [B] from the information processing apparatus 53. At this time, since the erasure priority mode is not set, the image forming apparatus 30 stores the received pre-print data [B] as a print file in the hard disk 19 and thereafter performs the same print processing as the print data [A] described above. This is executed in parallel with the processing of the print data [A]. That is, execute the processing 1 for the previous printing from the time t ₃₄ the data (B), from the time t ₃₅ executes the process 2 with respect to the print data before (B), before printing from the time t ₃₇ The process 21 is executed for the data [B], and the process 4 is executed for the pre-printing data [B] from the time ₃₈ .

  However, for the pre-print data [B], the size of the random number data stored in the random number storage unit 31 in step S602 of the overwrite process flow shown in FIG. It is determined that the print data size is smaller than the medium print data size. Accordingly, here, only the fixed data writing process is performed in parallel (substantially the same as the process 3 in FIG. 8 described above), and steps S205 and 206 in the flow of the print process shown in FIG. 4 are executed.

As described above, the image forming apparatus 30 repeatedly executes the random number data overwriting process according to the flow shown in FIG. 12, and at time t ₃₉ , the processing state of the printed data [B] printed out is changed to “ The print data management list 22 is changed so as to be “processed”. For this reason, there is no “unprocessed” file in the print data management list 22, and there is a “processed” file. The print data [B] is displayed at time t ₄₀ by the process of step S 704 in the flowchart. to generate a random number to overwrite the (process 5), the subsequent time t _41, the region generated random number data has been printed data in the hard disk (B) have been stored (in this area is already fixed Overwriting is started, the file of the printed data [B] is deleted and deleted from the print data management list 22 (process 6).

The print data [A], because already deleted in the process 21, the random number data overwriting process by the flow shown in FIG. 12 (processing 5, 6), the print data [B] at time t ₄₀ and time t ₄₁ Only executed for.

During this time, the CPU 11 is mainly used at the time of random number generation processing at time t ₃₁ or time t ₄₀ and at the time of image conversion from time t ₃₄ or time t ₃₇ and is used at the time of data processing for the hard disk 19 using DMA. Not. Therefore, it is possible to execute the write process to the hard disk 19 of the image conversion processing with the fixed data and the random number data at the same time from the time t ₃₄ or time t _37. Furthermore, in the process of processing the print data [A] and the print data [B] in parallel, it is possible to simultaneously access the print data to the hard disk 19. Incidentally, the period from time _{t 34} corresponding to the situation at time _{t 36,} utilization of the hard disk 19 is increased. Further, the image forming apparatus 30 takes into consideration that the image processing by the CPU 11 and the random number generation processing do not overlap with each other in steps S702 and 703 of the random number data overwrite processing shown in FIG.

  In the time chart of FIG. 13, the print processing period T1 is the time from the start of receiving the print data [A] to the completion of printing of the print data [B], and the print data erasing period T4 is all the print data (print data [A], the time from the completion of printing of the printing data [B]) to the completion of the random number data writing of the printing data [B].

  As described above, according to the printing system of the second embodiment, the overwriting process at the time of erasing the print data is divided, and the fixed data overwriting process is processed in parallel with the image conversion process. Since the random number data for overwriting is generated and stored in advance when the device is in the standby state, the processing until the writing of the random number data is processed in parallel depending on the conditions, so the print data erasure processing time after printing Can be further shortened compared to the case of the first embodiment.

1 is a block diagram schematically showing a main configuration of a printing system according to a first embodiment having an image forming apparatus of the present invention. FIG. 6 is a diagram for explaining a print data management list. 5 is a flowchart showing a flow of print data reception processing performed by the image forming apparatus according to the first and second embodiments. 3 is a flowchart showing a flow of a printing process performed by the image forming apparatuses according to the first and second embodiments. 6 is a flowchart illustrating a flow of a confirmation process of a total printed data size performed by the image forming apparatuses according to the first and second embodiments. 4 is a flowchart of fixed data overwrite processing performed by the image forming apparatus according to the first embodiment. 3 is a flowchart of random number data overwrite processing performed by the image forming apparatus according to the first embodiment. 3 is a time chart illustrating an operation example of the image forming apparatus according to the first embodiment. 3 is a time chart for illustrating a comparative example with respect to an operation example of the image forming apparatus according to the first embodiment. FIG. 3 is a block diagram schematically showing a main configuration of a printing system according to a second embodiment having an image forming apparatus of the present invention. 10 is a flowchart of an overwrite process performed by the image forming apparatus according to the second embodiment. 6 is a flowchart of random number data overwrite processing performed by the image forming apparatus according to the second embodiment. 6 is a time chart illustrating an operation example of the image forming apparatus according to the second embodiment.

Explanation of symbols

1, 2 Printing system 10, 30 Image forming device 11 CPU
12 RAM
DESCRIPTION OF SYMBOLS 13 Print data management part 14 Print control part 15 Communication control part 16 Image conversion part 17 Print data deletion part 18 Random number generation part 19 Hard disk 20 Common bus 21 Print data 22 Print data management list 31 Random number memory | storage part 51 Printing part 52 Network 53 Information Processing equipment.

Claims (10)

Print data storage means having a print data storage area for storing print data;
Print data erasing means for erasing the print data by overwriting different types of erasure write data in the print data storage area;
Print processing means for reading the print data from the print data storage area and performing print processing;
The print data erasing unit performs a primary overwriting of the erasure data on the storage area of the print data read by the print processing unit in parallel with the print processing of the print processing unit. The image forming apparatus, wherein after the print processing of the print processing means is completed, a second overwriting of the erasing data is executed.   The image forming apparatus according to claim 1, further comprising a random number generation unit, wherein the fixed data and the random number data generated by the random number generation unit are used as the erasing write data.   The random data generated by the random number generation unit at the time of the second overwriting is overwritten on the storage area of the print data read by the print processing unit at the time of the first overwriting. 3. The image forming apparatus according to claim 2, wherein the area overwritten with the fixed data is overwritten.   Further, a random number storage unit is provided, the random number data generated by the random number generation unit in the standby state is stored in the random number storage unit in advance, and is stored in the fixed data and the random number storage unit at the time of the first overwriting. 3. The image forming apparatus according to claim 2, wherein random number data is overwritten on a storage area of the print data read by the print processing unit.   The random number data stored in the random number storage unit is overwritten when the random number data size stored in the random number storage unit is equal to or larger than the print data size being printed. Image forming apparatus.   The image forming apparatus according to claim 1, wherein after the second overwriting is executed, an area where the secondary overwrite of the storage area is executed is released. Print data storage means having a print data storage area for storing print data;
Print data erasing means for erasing the print data by overwriting the write data for erasure that requires computation and the write data for erasure that does not require computation in the print data storage area;
Print processing means for reading the print data from the print data storage area and performing print processing;
The print data erasure unit overwrites the print data storage area read by the print processing unit with erasure write data that does not require at least the calculation in parallel with the print processing of the print processing unit. Then, after the print processing of the print processing means is completed, the erasure write data that requires the calculation is overwritten in a storage area that has been overwritten with the erasure write data that does not require the calculation. Forming equipment. A storage unit for storing write data for erasure that requires the calculation,
Write data for erasure that requires an operation in a standby state is generated and stored in the storage unit, and is stored in the storage unit and an erasure write data that does not require the operation in parallel with the printing process of the print processing means. 8. The image forming apparatus according to claim 7, wherein the erased write data is overwritten.   9. The erase write data stored in the storage unit is overwritten when the erase write data size stored in the storage unit is equal to or larger than the print data size being printed. The image forming apparatus described. The image forming apparatus according to claim 1, wherein the print data storage unit is a magnetic storage device.

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