Prior art image forming devices include copiers, facsimile machines and printers. A plurality of these image forming devices is connected via network. In the network system with the above connected image forming devices, collaboration may be performed among the image forming devices. For example, the collaboration reduces the operation time by dividing the tasks. For example, when a single original is to be copied one hundred times, the originating image forming device that is given the above task communicates with other image forming devices. As a result of the communication, the task is divided between two image forming devices so that each device copies fifty times.
In addition, prior art image forming devices scan the originals on the contact glass and store the image information in memory. Based upon the stored image information, an image is printed on the image transfer paper, and the repeated print operations provide a predetermined number of copies. In the above prior art image forming devices, a remaining memory amount is monitored while the originals are being scanned. The scanning operation is interrupted before the remaining memory reaches zero. The copy operation is determined by the user upon detecting the zero memory. The user can select either terminating the copy operation or starting the copy of the image information that has been already scanned. For example, if an automatic feeding mode is used to feed an original to the contact glass surface from the original tray of the automatic document feeder (ADF) and the remaining memory has reached zero, since some of the originals have been already outputted, the user has to put back the originals in the feeding tray after the user cancels the copy operation and retries the same copy operation.
For the prior art technology, the following reference Japanese Patent Publication 2000-69259 discloses that the image information is scanned by an arbitrary image forming device among a plurality of image forming devices, and the image information is transferred to another one of the image forming devices to distribute printing for improved operation in the network system.
In the prior art image forming devices, outputted transfer paper is wasted at a child device when a copy job is terminated in response to a memory full detection at the child device. Further, a single original bundle is unfortunately divided for output at a child device when a specified number of copies is outputted based upon the transferred image at the child image. It remains desirable to provide a highly efficient image forming device network system that causes no wasteful miscopy even when memory becomes full at a child device.
In the prior art image forming devices, a job is reserved on another machine or a child device before a print job is divided for the transferred image data. The next job reservation is made while the current print job is in operation, is being transferred, or is being printed as a divided job. As Japanese Patent Publication Hei 10-322533 discloses that copiers print out images in the storage unit even if a collaboration unit fails to make printers collaborate during the print operation in the image forming device network. The above printing under abnormal conditions continues as much as possible to prevent decreased productivity by terminating the print operation at other copiers.
The Print Operation
For the above prior art system, it is necessary to keep the image data in the storage unit so that the print job is continued until the print job is completed at any one of the printers in the system. However, since a child device may have another job in addition to the current collaboration job, to use the memory resources in an efficient manner, it is also necessary to remove image data that no longer requires the print division. For this reason, it remains desirable to provide an image forming device to efficiently utilize the memory resources in sharing a print job among image forming devices that are connected in common network.
Other prior art references such as Japanese Patent Publications Hei 10-74163 and 2001-13827 disclose the memory resource utilization techniques. To effectively utilize the common memory resources, a memory controller arbitrates the use of the common memory resource among a plurality of software application programs in multifunction devices as well as copiers, printers and fax machines as disclosed in Hei 10-74163. To guarantee a memory area for a collaboration job, a memory block is reserved. However, when there is no collaboration, the memory block is available for any other tasks by a single operation as disclosed in 2001-13827. Furthermore, the rest of the memory block is released if not used even during collaboration. However, the prior art techniques cause restrictions on the memory resources by other application program operations at a child device if the image data is transferred at the beginning of collaboration. For example, if the image data is transferred for collaboration during the execution of a previous job at a child device, the previous job may restrict the memory for a subsequent job. In a worst case, the previous and subsequent jobs compete for memory, and a deadlock may occur. Furthermore, when a next non-collaboration job is to be registered at a child device, the memory resource similarly may not be available. For the above reasons, it remains desirable to control the timing of transferring image data in order to increase the efficiency in the memory resource utilization at a child device.
There are other issues that are associated with image data transfers. As described above, Japanese Patent Publication 2000-69259 discloses a prior art technology that the image information is scanned by an arbitrary image forming device among a plurality of image forming devices, and the image information is transferred to another one of the image forming devices to distribute printing for improved operation in the network system. The image data is scanned by an arbitrary master or parent device among the image forming devices. Alternatively, the image data is already scanned and stored in an external memory storage unit. However, when the image data is distributed among child devices, the remaining memory amount may differ among the child devices. The parent memory may reach zero while the original is being scanned as the remaining memory is monitored. As a result, the original is returned, and it is inefficient. For this reason, it remains desirable to increase the productivity in scanning to distribute the image data among the image forming devices for sharing printing. In prior art technologies, remaining memory is monitored while original documents are scanned. Before the remaining memory reaches zero, scanning is interrupted. Then, a user is given a choice to select. He or she can terminate the copying operation. Alternatively, he or she can specify that the printing is initiated for the image data that has been already scanned. In prior art technologies, remaining supplies such as paper and toner are monitored. At the beginning of a job or during the job, a message is generated upon detecting any empty supply for an operator to provide exhausted supplies. The job is continued after supplies are provided. In the image forming device network system, a job is generated by a parent device and shared among child devices in collaboration as disclosed by Japanese Patent Publication 2001-238035. It remains desirable to monitor the supply level at each of the child devices during the assignment of the print job during collaboration.
In prior art technologies, a final image including from a parent device and a child device is printed at a child device in order to make the print output to be equal to that from a single image forming device. To provide the final image, it is desired that a new consolidated image is generated at a parent image in stead of transferring the scanned image data to the child image. For this reason, it is not necessary to store the image data at a child device, and the child device memory resource is efficiently utilized. Furthermore, it is desired to transfer the image data to a child device from the last page in the reverse order in case of the stack mode printing at a child device.