Network Scanning: A New Feature for Digital Copiers

Transcription

1 Network Scanning: A New Feature for Digital Copiers Abstract Introduction The method of implementing electronic document capture and distribution, known as network scanning, into the traditional copier/printer architecture is described. The addition of the network scanning component is the next step in the technological progression that originated with the copier model and continues through the network connected copier/printer model that is popular today. On a multi-function platform, contention issues between copier and printer functionality are further complicated by the introduction of the network scanning component. Network Scanning converts the scanned document image data into TIFF or PDF and formats it for delivery to user defined destinations utilizing SMTP and FTP protocols. The integration of network scanning into Sharp's Digital Imager printer/copier architecture is presented. Within the last decade, the office environment has seen the transformation of the office copier from an analog, standalone, single-purpose contraption into a digital, multipurpose, network connected peripheral with printer and copier functionality. The next step in this evolutionary process is re-routing the scanned document images, normally destined for the copier laser engine, into the connected network. Network Scanning transforms the prototypical copier capable of reproducing hard copy output into the front end for a document distribution system with and FTP delivery methods. With these capabilities, yet another dimension and business opportunity is added to the ubiquitous copier platform. Contention issues involving the addition of the network connected printer into the copier model were relatively simple to resolve. Walk-up copier operation had precedence over printer jobs at all times. If a print job was active and a user needed to make copies of a document, the print job would be interrupted until the copy job completed. Network Scanning is viewed by the system as a special type of copy job with one key exception: operation of the laser engine is not required for the scan job. So, it is theoretically possible for printing and scanning to occur simultaneously. In this paper, the software component architecture for Sharp's Digital Imager network connected printer/copier system is described. From that baseline system, the addition of the network scanning component, communication between the various embedded system components, and the importance of the real-time operating system will be presented. 1. System Description 1 1 Copier System Description The copier system architecture of Sharp's Digital Imager 58

2 Network Scanning: A New Feature for Copiers is shown in. A document that is to be reproduced on the copier device is placed in the RADF (Re-circulating Automatic Document Feeder) represented by. shows the graphical user interface that allows the user to enter the copy setup parameters (e.g. number of copies, output paper size, duplex or simplex, sorted and stapled, etc.) that control the copy job. The Intermediate Control Unit (ICU), in, contains the Scanner and Engine controller and the ERDH (Electronic Re-circulating Document Handler). The Scanner controller sets up and reads the image data from the CCD and then saves it to the ERDH which is implemented via an IDE hard disk drive unit. The Engine controller reads the image data from the ERDH and supplies the Laser Engine with the data for creating the impression on the paper. Communication between the Scanner and Engine controllers is provided by a SCSI-II connection. The Front Panel communicates with the ICU using a proprietary protocol over a serial port connection. The ERDH's ability to store the document image data and then allow re-reads for multiple copies prevents excessive wear on the CCD unit. This feature significantly extends the life of the scanning mechanism and the CCD unit. 1 2 Network Printer System Description Two key elements of this copier architecture provided the foundation for the addition of network printing: 1) the ERDH, and 2) the SCSI interface to the Engine Controller on the ICU. The ERDH's ability to store image data allows buffering of rendered pages. The SCSI interface provides a communication channel for the transfer of status and page image data from the dedicated printer controller hardware. describes the addition of the Printer Controller to the copier architecture described previously in. When a print job [ ] is submitted to the printer over the network connection, the NIC (Network Interface Card) [ ] receives and buffers the print job into memory and alerts the Printer Controller that data has been received and is ready for processing. The Printer Controller [ ] determines the PDL 59

3 (Page Description Language) required to render the document into image data for printing by the Laser Engine. As the images are rendered, they are transmitted over the SCSI interface to the Engine Controller. The Engine Controller stores all pages on the ERDH for use in making multiple copies or in error recovery. If a print job must be re-ordered (i.e. for printing in booklet mode), all pages are stored on the ERDH before printing begins. If there are no special re-ordering requirements, each page is printed as it is received and simultaneously stored on the ERDH. In the event of a paper jam or other error, the Engine Controller can quickly re-read the image data directly from the ERDH. A print job is designated Mode A when page re-ordering is not required. A Mode B print job requires page reordering to performed and printing is delayed until all pages are stored to the ERDH. Intuitively, Mode A print jobs are printed more quickly than Mode B jobs due to the requirement that Mode B must delay printing until the last page has been rendered and delivered to the ERDH. Also, the limited amount of storage available on the ERDH restricts the number of pages that can be printed in Mode B. Mode A, on the other hand, is sent directly to the Laser Engine and is not hampered by the ERDH limitation. 1 3 Network Printer System Software In the network connected printing system, the central issues are management of I/O communications and image rendering. Data enters the system through the NIC connection or the IEEE 1284 parallel port, is rendered page by page in the image processing software, and then is passed to the ICU via the Engine Interface over a SCSI connection. shows the network printer software architecture implemented on the Printer Controller hardware. The foundation of the system is the Board Support Package (BSP) which provides low-level interfaces and drivers between the hardware and the real-time operating system (RTOS). Communication ports (SCSI, Serial, 1284, etc.), interrupts, timers, and memory interfaces are handled at this level. This layer abstracts the hardware into a generic interface for the RTOS. At the application layer, running as a task on top of RTOS is the SNMP (System Network Management Protocol) component that provides device management information to the network. This allows network administrators to check machine status and configure the device remotely. The I/O Pipeline is the initial stage of the Interpreter component and connects into the Sniffer. The Sniffer determines the type of Page Description Language for the print job such as: PostScript (PS) or Printer Control Language (PCL). The Printer Job Language (PJL) component translates the attributes of the print job that control paper size, orientation, copy count, etc. The Queue Manager and Renderer components coordinate to provide storage and linked-list access to the rendered images. The Queue Manager uses the Renderer to transform data from an internal storage format to a bitmap image and then sends it to the Engine Controller on the ICU via the Engine I/F module. Semaphore signaling controls process operation and synchronization between tasks. It is also used to interrupt the rendering process when a higher priority operation, namely "walkup" copy, occurs, causing the communication and rendering tasks to block until the copy function has completed. 1 4 Network Scanning Description shows the integration of network scanning into the copier/printer architecture described in the preceding sections. Since network scanning is a "walkup" feature related to the copy function, the Front Panel [ ] provides the user interface for the setup of the scan job. The user would setup scanner attributes (e.g. resolution, PDF or TIFF file type, compression, etc.) and the scan job destination. The document to be scanned is placed in the RADF 60

4 Network Scanning: A New Feature for Copiers [ ] and the "Start" button is selected. As each page is scanned, the image data is stored onto the ERDH. When all pages have been scanned successfully the Engine Controller notifies the Printer Controller [ ], over the SCSI connection, that the scan job image data is ready to be transferred. Destinations for delivery of the scanned document are either an addresses or an ftp server and are selected by the user from the Front Panel. Multiple addresses may be grouped together for more efficient distribution of scanned documents. The Printer Controller requests the image data, a page at a time, converts the image to a TIFF or PDF file, compresses it in the selected format, and sends it out through the NIC over the network [ ] to the selected destination. Elements of both network printing and copying are combined to provide the network scanning functionality. The implementation of bi-directional communications between the Printer Controller, Engine Controller, and Scanner Controller allows the movement of critical status and image data between the distributed systems. Connection to the network via the NIC, with back-channel capabilities, provides the ability to deliver to destinations utilizing the standard network protocols FTP and SMTP. 1 5 Network Scanning Software System The ability of these features working together successfully centers on the implementation of the software architecture. The RTOS provides the scalability required to add the network scanning component to the network connected printer on the Printer Controller hardware. The RTOS package provides robust, reliable, and predictable task management and task communication functions that facilitated the implementation of network scanning software. Due to the asynchronous nature of the events involved in both printing and scanning, it is necessary that the operating system handle numerous task switching duties with high reliability. The embedded HTTP server component provides access to the embedded web pages allowing administration of network scanning. No special application program is required for configuration or operation of this feature. Access to all of the features can be obtained via any of the popular web browsers. illustrates how the network printer software architecture accommodates the Network Scanning components. The N/W Scan, HTTP, SMTP, and FTP modules are integrated into RTOS as tasks. FTP and SMTP can create multiple task sessions to allow for numerous connections - one of the many benefits of implementing a multi-tasking operating systems. Network Scanning communicates directly with the Engine Interface through a set of application program interfaces. These APIs provide services for display of the 61

5 Destination Profiles on the Front Panel LCD, retrieval of the scanned document image data, and status information. There are 3 main tasks that comprise the Network scanning component as detailed in These are the Scan Task, Formatting Task, and Delivery Task. The Scan Task interfaces with the Engine I/F for communication over the SCSI channel. Scanner configuration, initiation, servicing of the scan job request, receiving of the scan job image data, and providing information to the user interface are all handled by this task. When the image data is received by the Scan Task, a message is sent to the Formatting Task containing the image format and image data. This task converts the raw image data into the selected file format, either TIFF or PDF. It then applies the user selected compression (e.g. G3, G4, Uncompressed) to the file. When a sufficient amount of data has been places into the file, a message is sent to the Delivery Task so that delivery of the file can proceed. Files are delivered to the network through either (SMTP) or FTP protocols. Communication between the NIC and SMTP and FTP modules is accomplished with a sockets interface, also developed specifically for the Network Scanning component. The scanned document is attached to the message in MIME encoded format. Standard FTP function calls are used to save the converted file to the server specified as the destination when the document was scanned. Efficient management of system RAM was critical in the network scanning implementation. Other resources in the system require a minimal amount of memory to provide functionality. Performance during the rendering of a print job is directly related to the amount of memory installed in the system. It was a requirement that the addition of network scanning could not degrade the performance of the printing process. In order to achieve this requirement, network scanning allows segmenting of scan job file data into discrete sections. This sectioning, or banding, of data permits the sending of documents whose size greatly exceed the available system RAM. While at the same time leaving enough RAM for other tasks to execute simultaneously. Conclusion The successful implementation of Network Scanning into the Network Printer and Copier architecture was the result of many factors: Communication channels among the various embedded systems in the device that provide reliable data transfers between the Scanner Controller, Engine Controller, and Printer Controllers, the storage capabilities of the ERDH for scanned document page images, an RTOS providing flexibility for the addition of the network scanning tasks and reliability in the management of communication between the tasks. All of these elements contributed in providing a manageable development process. Future development and feature enhancements, to this architecture, will be facilitated by the existing infrastructure. Yet another benefit of good design combined with the implementation of a robust real-time operating system that is flexible enough to accommodate the addition of new features (i.e. tasks) to the Printer Controller. The metamorphosis of the printer/copier from a singlepurpose device into the entry point of a network connected document capture and distribution system is just the beginning for this denizen of the office workplace. 62