Input and output scanner

Abstract: A compact combined input scanner and output scanner having a frame assembly (15) with a scanner carriage (20) movably mounted for movement in a scann path along the length of the frame assembly. The scanning carriage has a read head (23) secured thereto for scanning a document to produce a digital image of at least a portion of the document, and a write head (25) secured thereto for relative movement with respect to a copy sheet and electrically connected to the read head for printing a digital image on a copy sheet. The frame assembly includes copy sheet and document transport paths, with an indexer to index a document through the document path in a direction transverse to the scan direction, and to index a copy sheet through the copy sheet path in the opposite transverse direction.

Description: The present invention relates to a very low cost portable compact scanner. More particularly it is directed to a compact device employing a single scanning carriage incorporating a read head and a write head to permit essentially simultaneous reading of an original document and writing of a copy. Historically, copies of original documents have been produced by a xerographic process wherein the original document to be copied is placed on a transparent platen, either by hand or automatically through the use of a document handler, and the original document illuminated by a relatively high intensity light. Image rays reflected from the illuminated document are focused by a suitable optical system onto a previously charged photoconductor, the image light rays functioning to discharge the photoconductor in accordance with the image content of the original to produce an electrostatic latent image of the original on the photoconductor. The electrostatic latent image so produced is thereafter developed by a suitable developer material commonly referred to as toner, and the developed image transferred to a sheet of copy paper brought forward by a suitable feeder. The transferred image is thereafter fixed to the copy paper by fusing to provide a permanent copy, while the photoconductor is cleaned of residual developer preparatory to recharging. More recently, interest has arisen in electronic imaging where, in contrast to the aforedescribed xerographic system, the image of the document original is converted to electrical signals or pixels and these signals, which may be processed, transmitted over long distances, and/or stored, are used to produce one or more copies. In such an electronic imaging system, rather than focusing the light image on to a photoreceptor for purposes of discharging a charged surface prior to xerographic development, the optical system focuses the image rays reflected from the document original on to an image-reading array which serves to convert the image rays to electrical signals. These signals are used to create an image by some means, such as operating a laser beam to discharge a xerographic photoreceptor, or by operating some direct marking system such as an ink jet, direct thermal or thermal transfer printing system. It would be advantageous if the normally-separate document reading and copy printing operations could be combined. If some of these reading/writing functions could be combined, system operation and synchronization could be simplified and system cost reduced through the use of fewer parts. There are systems in the prior art that address the above identified concerns. For example: US-A-4,496,984 and US-A-4,583,126 disclose an input/output scanner for simultaneously reading a document and writing a copy. The document and copy sheet are fed in back-to-back relation to the read/write station. A monolithic full-width reading array reads each line in two steps, to improve resolution. The writing array consists of rows of ink jet nozzles, of which the number and disposition is in direct correspondence to the sensors of the read bar. US-A-4,424,524 discloses a full-width read/write LED array for scanning a document in the read mode or exposing a photoreceptor in the write mode. An optical fiber lens array is used for focusing the full-width LED array on the document or photoreceptor. A difficulty with these known systems is the complexity and cost of separate components, such as the complex optics, photoreceptor and developer in a typical xerographic process. In other systems, it is necessary for an operator to combine a document and copy sheet manually into a single unit for manual insertion to machine feed rolls. Such a system also has a significant cost penalty associated with components such as the monolithic full-width reading array. It is an object of the present invention, therefore, to provide a read/write scanner/printer system in which a read head and print head are both substantially smaller and less expensive than a full-width array component, and co-mounted on the same single scanner carriage to read a stationary document and print a copy on a copy sheet substantially simultaneously. It is another object of the present invention to provide a document that is read, and a copy that is printed, in a series of bands across the document and copy, that is, after each band of information is read and printed, the document and copy sheet are indexed relative to the read and write components so that the next band of information can be read and printed. Most reproduction devices, and in particular copiers, in commercial utilization are intended for permanent or semi-permanent location in an office environment. Indeed some are so large, complex and expensive that only sizable office environments can support then. There is, however, a great need for a portable copier. There is a particular need for very low cost, very compact copiers which enable convenient reproduction of documents at sites remote from an office environment. While many efforts have been made, there is a continuing need for a smaller, more compact, lower cost copying capability. US-A-4,319,283 discloses a portable copying machine. A light-receiving element and a thermal-recording head are both mounted upon a single moving element. The thermal recording head is stationary, while the light-receiving element is movable in a longitudinal scanning direction. A heat-sensitive record sheet is moved in correspondence with lateral movement of the light-receiving element. The machine achieves copying without such components as an image-forming optical system, a photosensitive element, a developing mechanism, and a fixing mechanism. US-A-4,574,317 discloses a hand scannable portable copier for use in copying documents or excerpts of documents, comprising a solid state optical sensor array in a thermal print head array supported within a pocket sized housing. Copies are made using a thermal copy sheet by passing scanning light through the copy sheet, reflecting light back from the original image and copying underneath. A battery supplies power to the copier. US-A-4,823,195 discloses an apparatus in which combined reader and printer heads are scanned together across a document and a copy sheet to process the image lines block by block. As each scan is completed, the document and copy sheet are stepped ahead in synchronization with one another by a distance equal to the width of the block of lines scanned. In addition there are several devices, including hand-held copiers, that use direct thermal printing technology for direct marking on to imaging widths of from 40 to 100 millimeters wide. In US-A-4 920 421 a combined input and output scanner is described wherein a scanning carriage has secured thereto a reading head and a printing head which carriage system scans across a document scanning a band of information across the document on a platen. The carriage system has a separate indexing mechanism to index the scanning carriage to a second position to scan another band of information across the document. The present invention is directed to a small combined input/ output scanner system of ultra compactness, very low cost and, a high degree of portability. While the principle capability of the combined input/output scanner is in the production of copies from original documents, it has the additional capability of operating as a printer, a scanner or a facsimile device, providing a truly multi-mode capability. Accordingly the present invention provides a compact combined input scanner and output scanner comprising a frame assembly containing a carriage movably mounted for scanning movement in a scanning path along the length of the frame assembly, the carriage including a read head secured thereto for scanning a document to produce a digital image of at least a portion of the document, and a print head secured thereto for relative movement with respect to a copy sheet and electrically connected to the read head for printing the digital image on the copy sheet, the frame assembly including copy sheet and document transport paths including means indexing a document through the document path in a direction transverse to the scan path, and for indexing a copy sheet through the copy sheet path in the opposite transverse direction, characterised in that the read and write heads are arranged oppositely-facing so that the right-hand pixel of the read head coincides with the lead edge of a portion of a document to be copied and the left-hand pixel of the print head coincides with the lead edge of the print of said portion on a copy sheet, to form a right reading image on the copy sheet. In a further aspect of the present invention, the scanning carriage is movably mounted between the plane of the document transport path and the plane of the copy sheet transport path. The present invention will now be described by way of example with reference to the accompanying drawings, in which the same reference numerals have been applied to the same parts in several figures. Figure 1 is an exploded isometric view of a compact copier according to the present invention; Figure 2 is a schematic cross-sectional view of the copier shown in Fig 1. Figure 3 is a plan view illustrating the scanner carriage system; Figure 4 is a sectional view along the line A-A of Figure 3, illustrating the elements of the scanner carriage; Figure 5 is a sectional view taken along the line B-B in Figure 3, illustrating the registration mechanism for both the document and the copy sheet; Figures 6A, 6B, and 6C are three isometric views illustrating the general operation of the copier, and Figure 7 is an illustration of the scanning operation. Referring now to Figures 6A, 6B and 6C, a general overview of the compact portable copier according to the present invention is provided. The copier is generally illustrated as comprising a frame assembly 15 having a maintenance station 12 at one end and a top cover 11 pivotally mounted on the frame assembly. To make a copy of a document 14, the top cover is rotated to the open position as shown in Figure 6A, a copy sheet 13 is inserted at the entrance of the copy sheet transport path, and the document 14 is inserted against a registration stop member in the top cover, after which the top cover is closed and the copying sequence begins by the scanner carriage scanning a band across the document. During the scanning operation, the image on the document is digitized by an input digitizing system and, in the preferred embodiment, a digital image is substantially simultaneously printed on the copy sheet by a printing system. Subsequently, the document is indexed to the right as viewed and the copy sheet is indexed to the left as viewed to enable the scanner carriage to scan a second band across the document in the reverse direction. The distance through which both the document and copy sheet are indexed is the width of the scan band. Referring to FIGS. 1 & 2, there is shown a combined input and output scanner. The scanner 10 includes a frame assembly 15 composed of a base unit 18, rails 19 on which scanner carriage 20 is transported during its scanning. When not in operation, the carriage 20 is parked in the maintenance station 12 where it is protected from contamination and maintained in a relatively constant environment. For input scanning, an imaging assembly includes an illuminator 21, which may be an array of light-emitting diodes (LED) or any other suitable device, a mirror 22, a lens 23, which may be a Selfoc lens, and an input digitizing chip 26 which may be a charge-coupled device (CCD) or any other suitable device for receiving optical signals and converting them into electronic 'pixel' information in a data register. As this assembly scans or reads a document 14, the image area is converted to electric image signals or pixels. The image signals generated by the read head are input to a print bar 25, which may be any suitable direct-marking device, such as a direct thermal or thermal transfer head, or preferably a thermal ink jet array 25, to write copies of the document in accordance with the image signals on to a suitable substrate or copy sheet 13. It will be understood that the number of scanning elements or sensors per unit length that comprise the image read bar 17 determine the initial scanning resolution, while the number of ink jet nozzles 27 per unit length that comprise the print bar 25 determine the resolution of the image copy. In a preferred embodiment, the number of input scanner elements equals the number of output printing elements. Both the scanner head and the print head are secured on scanning carriage 20, which is mounted for either undirectional or bi-directional scanning movement in a path along the length of the frame assembly, by means of scan motor 32 through gear 31, pulleys 29 and 30, and cable 28, to move the scanning carriage along the rails 19. The movement of the scan carriage 20 supporting image read assembly 21, 22, 23, 26 and print bar 25 is further illustrated with respect to Figure 7. Arrows 33a and 33b illustrate the forward and reverse scan of the carriage 20 across a document and copy sheet, also shown in Figure 2. The arrows 68 illustrate that a number of pixels, perpendicular to the direction of movement of scan carriage 22, are both read by the read assembly and printed by the print bar as the carriage scans the document and copy sheet. In a typical embodiment, 192 pixels at 12 per mm are read and printed perpendicular to the movement of carriage as it scans. In this example arrow 68 represents a band of information 83 µm long and 16.26 mm wide which is read and printed. The movement of the carriage can be continuous or in discrete steps, but in a preferred embodiment, the 192 pixels are read and printed in increments that are one pixel apart as shown. In one embodiment, each time the scan carriage moves a distance of one pixel width across the sheet, the electronic image of 192 pixels down the sheet are moved into a shift register and then amplified and shifted in reverse order into the print bar to fire the 192 ink jets and thereby create a print of the 192 pixels previously read. This sequence is repeated each time the scan carriage has moved a distance of one pixel width. It should be noted that the scanning could also be done with 192 parallel channels, each channel reading and writing a single line of pixels as the carriage sweeps across the page. While it is preferred that the read/write operation be substantially simultaneous, a digital buffer or register could be incorporated to store the scanned or read signals initially for printing later after a predetermined or arbitrary period. The combined scanner illustrated has multi-mode capability, and could be operated independently as a printer modulated by any suitable device providing digital information, operated independently as a scanner to convert source documents to a digital representation, operated as a facsimile device using the read and write elements when combined with a suitable modem, or operated as a copier by combining the scanning and printing operations. Following a scan in either direction across the length of the frame assembly, the document and copy sheet are each indexed through the scanner in opposite directions a distance equal to the width of the band of information on the document scanned by the read head, which is the same as the width of the band of information printed on the copy sheet by the print head. This width can be any width from a minimum of a single pixel line to a maximum of the width of the entire document. In practical terms, however, in order to keep the cost of the read and write components low, the width of the band is of the order of a few mms to several decades wide. The mechanism for achieving this is illustrated with further reference to FIGS. 1, 2 & 3, wherein an indexing means is provided at one end of the frame assembly, comprising a pair of synchronously-driven rotatable drive rolls 35 forming a feed nip for a document, with document feed idler rolls 42 contained within the top cover 11 of the scanner. The term 'synchronously driven' is intended to mean only that the drive rolls 35 are synchronized to each other. The drive rolls 35 also form a feed nip for a copy sheet with the copy sheet idler rolls 46 in the copy sheet transport path. The drive rolls 35 are driven by index motor 38 through pulley 37 and belt 36. The scan motor 32 and the index motor 38 are controlled by logic 33, as illustrated in Figure 4. With additional reference to Figure 5, the top cover 11 is pivotally mounted to the frame assembly 15, in particular the base unit 18, and pivots about points 41. When the top cover is pivoted to the open position, the document feed idler rolls 42 are disengaged from the drive rolls and the registration edge 44 is inserted into the plane of the document transport path, enabling the placement of a document to be copied in the scanner with its lead edge registered and inhibiting transport of the document through the document transport path. In a similar manner, the first incoming copy sheet idler roll 46 in the base unit is retracted from engagement from the drive roll 35 by linkage (not shown) when the top cover is raised to the open position. Similarly, registration gates 47 are inserted into the copy sheet transport path to enable manual registration of the copy sheet. In a preferred embodiment, the circumference of the drive rolls is equal to the width of the band to eliminate run out and shaft straightness tolerance defects which otherwise might cause some mis-registration between scan widths. As further illustrated in Figure 4, the base unit 18 has ink supply 49 connected to the ink jet print head 27 by means of a flexible umbilical ink supply tube 50. While the scanner of the present invention may have power supplied by conventional connection to domestic mains, Figure 1 illustrates a preferred embodiment wherein a rechargeable battery 43 is contained within the top cover. In operation, when the top cover is opened the idler rolls in the document path which are mounted in the top cover are moved out of position enabling placement of the document against front registration edge which is part of the top cover assembly. Opening the top cover also causes the first incoming copy paper idler roller to disengage from its drive roller, and a set of registration fingers in the copy paper path to move into the copy paper path. A copy sheet may be inserted from the right until its lead edge contacts the registration fingers, and a document may be inserted from the left on the top of the scanner face down. Following insertion of the copy sheet and the document, the top cover is closed, thereby re-engaging both the copy paper and document idler rolls with the drive roll. In addition, the copy paper registration fingers are withdrawn, two sensors (not illustrated) detect that both the document and the copy paper have been loaded accordingly and the logic initiates the copying sequence. The scan carriage containing the read and write head disengages from the maintenance station and scans across the document and copy sheet while both remain stationary. The document is positioned so that its lead edge coincides with the right side pixel of the read head, and the copy paper is positioned so that its lead edge coincides with the left side pixel of the print head. This enables the formation of a right reading image in the copy sheet. A line of information on the document read on the right extreme of the image read head fires the print head on the extreme left of the printing array during the scan of the carriage 20. This may be illustrated with reference to Figure 5. The pixel data received by the input chip at the extreme right of the chip (R) as the carriage 20 moves in the direction into and out of the paper transmitted and amplified to modulate the print head to fire the print head at the extreme left (L) of the print head. This scheme enables the printing of right reading copies with essentially simultaneous reading and writing without information storage. As the carriage scans across both the document and the copy paper, the 16.26 mm band of information being read off the document is immediately printed on to the copy paper. When the first scan is complete, the carriage motion stops. Both the document and copy paper are then indexed in a direction transverse to the scanning direction by the width of the band just scanned. This indexing is accomplished by driving the single pair of drive rolls which engage the document at the 12:00 position with the document feed idler rolls forming a feed nip therebetween, and the copy paper at the 6:00 position with the copy sheet feed idler roll forming a feed nip therebetween. The clockwise motion as viewed of the drive rolls through one revolution causes a document to be indexed 16.26 mm to the right, and the copy paper to be indexed 16.26 mm to the left. In this way the second band on the document is moved into a position over the scan carriage, and a second portion of the copy paper is moved to a position under the print head. The scan carriage scans across the document and copy paper in the reverse direction from the first scan, again reading the document and immediately printing the copy. Alternatively, the scan carriage may return to the maintenance station without reading/writing, and then start its next scan in the same direction as the previous scan. This sequence is repeated until the entire document is read and the entire copy is printed, after which the print head returns to the maintenance station and is parked. After the last scan across the document and copy paper is completed, the index motor is activated to eject the trail edge of the document to the right, and the copy sheet to the left, after which the scanner returns to the dormant state until the top cover is again opened and closed to reinitiate the next copy sequence. Thus according to the present invention a very low cost compact multimode portable scanner has been provided. This scanner may even be so economical that it can be disposed of by the user at the end of its normal life, or discarded in the event of need for repairs. Major cost is eliminated by eliminating the platen, the platen cover, paper insert hold down and eject mechanisms, by using a single pair of drive rolls which index both the document and the copy paper. The reading and printing functions can be performed virtually simultaneously, thus eliminating the need for electronic memory for information storage. Furthermore, in a preferred embodiment, the scanning operation may be bi-directional in both reading the document and printing on the copy sheet thereby increasing the overall throughput of the scanner. While the invention has been illustrated with respect to having an indexing mechanism for the document and copy sheets on only one side of the scanner, a similar indexing mechanism may be provided on the opposite side of the scanner. Further, as discussed above, while the invention has been illustrated as a copier, it is also capable of being operated independently as a printer, scanner or facsimile device.

Claims: A compact combined input scanner and output scanner (10) comprising a frame assembly (15) containing a carriage (20) movably mounted for scanning movement in a scanning path along the length of the frame assembly, the carriage including a read head (23) secured thereto for scanning a document (14) to produce a digital image of at least a portion of the document, and a print head (25) secured thereto for relative movement with respect to a copy sheet (13) and electrically connected to the read head for printing the digital image on the copy sheet, the frame assembly including copy sheet and document transport paths including means (35, 42) indexing a document through the document path in a direction transverse to the scan path, and for indexing a copy sheet through the copy sheet path in the opposite transverse direction, characterised in that the read and write heads are arranged oppositely - facing so that the right-hand pixel of the read head (23) coincides with the lead edge of a portion of a document to be copied and the left-hand pixel of the print head (25) coincides with the lead edge of the print of said portion on a copy sheet, to form a right reading image on the copy sheet. A scanner of claim 1, wherein the reading and printing occur essentially simultaneously without information storage. A scanner of claim 1 or 2, wherein the carriage is mounted for bi-directional scanning movement in the frame assembly. A scanner of any preceding claim, wherein the scanner carriage is movably mounted between the plane of said document transport path and the plane of said copy sheet transport path. A scanner of claim 4, wherein the document transport path is above the copy sheet transport path, and the read head and printing head are mounted on the scann carriage for reading a document face side down in the document transport path, and printing a digital image face side up on a copy sheet in its transport path. A scanner of any preceding claim, wherein when the carriage moves in its scan path the read head scans a band across the document and the print head concurrently prints the same band of information across a copy sheet, and wherein, upon completion of the scanning movement, the indexing means indexes the document and copy sheet through their respective paths a distance equal to the width of said band before the carriage scans another band across the document. A scanner of any preceding claim, wherein the indexing means includes a first pair of synchronously driven rotatable drive rolls (35), each drive roll forming a feed nip for a document with a document feed idler roll (42), and a feed nip for a copy sheet with a copy sheet feed idler roll (46). A scanner of any preceding claim, wherein document feed idler rolls (42) are mounted in a top cover (11) for the frame assembly, the cover being pivotally mounted to the frame assembly and having a document registration edge which extends into the document transport path when the top cover is pivoted to the open position, whereby when the cover is pivoted to the open position, the document feed idler rolls are disengaged from the drive rolls and a document may be placed in the document transport path and its lead edge registered. A scanner of claim 8, including a copy sheet registration edge which is movable into the copy sheet transport path in response to pivoting the cover to its open position to enable the lead edge of a copy sheet inserted along its path to become registered. A scanner of claim 9, including means, responsive to moving the cover from its open to its closed position, for reengageing the document and copy sheet idler rolls with their drive rolls, or any intervening sheets; withdrawing the registration edge, and initiating the copy sequence. A method of copying a document on to a copy sheet without information storage, comprising the steps of: scanning oppositely-facing read and write heads in a path across a document and copy sheet in a first direction; indexing the document and copy sheet relative to the scan path a predetermined distance in a transverse direction, and repeating the successive scanning and indexing motions the read head reading a portion of the document during the scan movements across the document, and the write head printing a portion of a copy during its movement across the copy sheet, characterised in that the read and write heads are arranged oppositely-facing so that the right side pixel of the read head coincides with the lead edge of a portion of a document to be copied and the left side pixel of the print head coincides with the lead edge of the print of said portion on a copy sheet to form a right reading image on the copy sheet.

Inventors: STEMMLE DENIS J, STEMMLE, DENIS J.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1991
Main classification: H04N1
IPC codes: H04N1