SHEET SORTING APPARATUS FOR AN ELECTRONICALLY CONTROLLED SHEET PRINTER

Abstract: For stored sheet collection from an electronically controlled sheet printer (1) in connection with a data or word processing system (5) a sheet sorting apparatus is designed as a supplementary unit (7) comprising a sheet supply slit (8) located opposite a sheet discharge slit (2) of the sheet printer (1). To selectively activate sheet guide means (14) the sorting apparatus comprises a control unit (16) connected into the signal transmitting connection between the data or word processing system (5) and the sheet printer (1) and is programmed to separated sorting control codes added in the data or word processing system (5) to the character information and printing control codes determined for a print page. When used in a multi-user system with a group of sorting bins (13) connected with each individual user device (5 to 5c) the sheet printer and the sorting apparatus (7) may be used simultaneously by the users.

Description: Sheet sorting apparatus for an electronically controlled sheet printer. This invention relates to a sheet sorting appara¬ tus for an electronically controlled sheet printer in connection with a data or word processing system from which character information and printing control codes are transmitted to the sheet printer by signal sequences each of which contains all symbol information and print¬ ing control codes for one page to be printed, said sheet sorting apparatus comprising preferably superposed sorting bins with individual, selectively operable sheet guide means adapted to feed a sheet to an arbitrary bin. When printing information from data or word pro¬ cessing ' systems on separate sheets, so-called page prin¬ ters, e.g. in the form of laser printers or jet ink printers are increasingly spreading because they allow a considerably greater printing speed than usual line printers of the type operating by mechanical impact. Due to the increased printing speed particularly obtained by printers having a xerographic reproduction system it is, however, in practice a severe drawback that the printed sheets in most cases are delivered completely unsorted by the printer. Said drawback occurs both when preparing more copies of a multipage document and in cases where a number of individual user devices of a multiuser data or word processing system make use of a common printer. It is the object of the invention to provide a sheet sorting apparatus fully remedying said drawbacks by allowing a sorted sheet collection from an electro¬ nically controlled sheet printer of said type. For this purpose the sheet sorting apparatus is according to the invention formed as a supplementary unit having a sheet supply slit to receive sheets from a discharge slit of the sheet printer and comprising a control unit to be connected into the character informa¬ tion connection between the data or word processing sy¬ stem and the sheet printer, said control unit being adapted to separate in each transmitted signal sequence a sorting control code applied by the data or word pro¬ cessing system and being connected to said sheet guide means and a driving motor for sheet feeding means in the sorting apparatus for the control thereof on the basis of the separated sorting control code and a control signal supplied to the control unit from a first sheet sensor located at the sheet supply slit. The invention is based on the recognition of the fact that the printing information transmitted from the data or word processing system to the sheet printer besides character information includes particular control codes to start the printing, to determine for¬ matting of the print etc. Said printing control codes vary dependent on the type of the sheet printer. The sorting apparatus according to the invention is based on the fact that such control codes may be used for other purposes, e.g. sheet sorting, to the extent where not reserved for printing functions in the sheet printer. The sorting apparatus according to the invention will, with the needed adaptation to the control codes as practised, be applicable together with arbitrary sheet printers of the type concerned, and such data and word processing systems with which said printers are capable of cooperating without requiring any change in the sheet printer itself or the data or word processing system it cooperates with, or any modification of their control software. The separation of the sorting control codes is in a preferred embodiment of the sorting apparatus accord- ing to the invention effected in that the control unit comprises a microprocessor having means for comparing the information supplied from the data or word proces- sing system to a number of prescribed sorting control codes and a storage containing control information for executing sorting functions in response to the control signal from said first sheet sensor and in dependence on a sorting control code separated by said comparison. The fact that by using the sorting apparatus according to the invention an "intelligent" control unit is so to say inserted between the data or word process¬ ing system and the sheet printer, further opens up the possibility of a quick and reliable detecting of error conditions such as paper jam and the like, resulting in that an ordered sheet printing will not be completed. In this respect the invention provides in a simple manner for ensuring a quick reproduction of a printed page which would otherwise be lost, in that the control unit further includes a buffer memory divided into a number of memory sections which individually receive and store all the character information and printing control codes pertaining to a determined page to be printed before they are transmitted to the sheet printer. The sorting apparatus according to the invention is particularly suited for use in connection with sheet printers shared by individual user devices, in that it allows distribution of printed sheets from the indivi¬ dual display terminals to individual sorting trays. This type of printing (shared print) thus opens up the new possibility that more users may have their printing done at the same time at the expense of a certain reduction of the printing velocity at disposal of the individual user. In order to obtain this, an embodiment of the sorting apparatus according to the invention is charact- erzied in that it comprises inputs for standard signal transmitting cables from a number of user devices and that the microprocessor in a normal working condition is programmed to allocate a number of definite sorting bins with each of said user devices. The invention will be more fully explained in the following with reference to the schematical drawings, in which Fig. 1 illustrates an embodiment of a sheet sort¬ ing apparatus according to the invention in connection with an electronically controlled sheet printer and a data or word processing system, Fig. 2 is a simplified block diagram of a control unit in the sheet sorting apparatus, and Figs 3 to 5 are flow diagrams explaining the mode of operation of the sheet sorting apparatus. The sheet printer illustrated in Fig. 1 is a so- called page printer and may for instance be constituted by an electrophotographic information printer of the type disclosed in the published international patent specification No. WO ' 84/03972. Only the sheet discharge slit 2 is shown in the figure of the printer 1 that is supposed to be structured in a manner known per se, said slit being located opposite a pair of sheet feeding rollers 3, 4 effecting the sheet transfer from the last sheet processing unit, e.g. a fixing device in a xerographic reproduction system to the discharge slit 2. The sheet printer 1 is electronically controlled from a data or word processing system 5 from which char¬ acter information and printing control codes in binary signal form may be transmitted to the sheet printer 1 over a cable connection 6. Said transmission of signals is effected by signal sequences individually containing all character information and printing control codes for a full printed page, the transmission being effected from a storage or a disc in the data or word processing system 5. As signal output unit and signal input unit, re¬ spectively, to an from the cable connection 6 the data or word processing system 5 and the sheet printer 1, respectively, comprise standardized interfaces, e.g. of the types RS 232 C, RS 422 or Centronics. The printing control codes transmitted in addition to the character information are utilized in the sheet printer 1 as control commands to start the printing operation, to determine the format of the print, printing type, number of copies etc., and as regards a determined combination of a data or word processing system and sheet printer they have the form of definite binary signal words beginning for instance with a particular bit-combination which identifies the signal word concerned as a printing control code and indicates the type of the control com¬ mand concerned, respectively. The data or word processing system 5 is illu¬ strated in Fig. 1 as an operator's display terminal with an associated keyboard, but it may as well-be an automa¬ tically operated printer unit, i.e. operated without manual assistance. The sheet sorting apparatus according to the invention is designed as a supplementary unit 7 to be connected with the sheet printer 1 and comprises a sheet supply slit 8 which, when coupled to the sheet printer 1, is located opposite the sheet outlet slit 2 therof to receive sheets directly from the printer 1. The sheet supply slit 8 constitutes the inlet to a sheet feeding path determined by a number of pairs of feeding rollers 9, 10, 11 and 12, said sheet feeding path extending vertically upwards in the illustrated embodiment from the supply slit 8 past the inlet ends of a number of horizontal superposed sorting bins 13. At the sheet inlet end of each of the sorting bins 13 finger-shaped sheet guide means 14 are provided by which a sheet may be fed selectively from the feeding path into a determined sorting bin 13, the sheet guide means 14 of each bin 13 being movable by means of an actuation device 15, e.g. a solenoid, from a position in which they block the inlet to the bin 13 concerned and a posi¬ tion in which they are turned out for engagement in the sheet feeding path in order to guide a supplied sheet into the associate bin 13. For the control of sorting functions the sorting apparatus 7 accommodates a sorting control unit 16 con¬ nected into the signal transmitting connection from the data word processing system 5 to the sheet printer 1 so that character information and printing control codes from the device 5 instead of being directly transmitted to the sheet printer 1 through the link connection 6 are now transmitted through a cable 17 to the sorting con¬ trol unit 16 and therefrom through a cable 18 to the sheet printer 1. In addition to control signal connections 19 to the actuation devices 15 for the guide means 14 , designed as solenoids, a control signal connection for a driving motor 20 of the pairs of sheet feeding rollers 9 to 12 is connected to the sorting control unit 16. More¬ over, for control and alarm purposes, sheet sensors 21 and 22, whose function will be more fully explained in the following, and an alarm indicator 23 which may be disposed either in the sorting apparatus 7 or as a remote indicator on the data or word processing system 5 are connected to the unit 16. As mentioned above the invention is based on the recognition of the fact that the control codes generated in the data or word processing system to the extent when not beforehand reserved for print commands may be used for other purposes, for instance sorting. In the embodiment illustrated in Fig. 2 the control unit 16 comprises a microprocessor 24 with an associated unit (input/output) 25 receiving via the cable 17 the data signals consisting of character infor¬ mation, printing control codes and sorting control codes from the data or word processing system 5 in Fig. 1. The individual data words of the transmitted signals are compared by the microprocessor 24 to a number of sorting control code words permanently stored in a ROM-memory 26 with a view to separating the data words representing sorting control codes. If the result of the comparison is negative corresponding to the case of the data word concerned representing either a character information or a printing control code, the data word is read into a buffer memory 28 formed as a circular memory divided into a number of memory sections 28a 28n each having a storage capacity capable of recording all character information and printing control codes per¬ taining to one page to be printed containing alpha- numeric symbols. In this respect it is remarked that, as regards a print page with graphics, it might be necessa¬ ry to make use of more than one memory section for re¬ cording the required symbol information. If the result of the comparison is positive cor- responding to the case of the recorded data word repre¬ senting a sorting control code, the data word is stored in a separate buffer memory 29 likewise formed as a cir¬ cular memory addressed synchronously with the memory 28 so that the sorting control codes recorded in the memory sections of the memory 29 are unambiguously linked to the information of print pages recorded in the memory sections of the storage 28. The flow diagram in Fig. 3 illustrates the above specified processing of the signals transmitted from the data or word processing system 5 in Fig. 1. The diagram illustrates the processing of the data words transmitted to the sorting control unit 16 in a signal sequence pertaining to a determined printed page, page j, in a situation where there is an unoc- cupied section in each of the circular memories 28 and 29. If the applied data word constitutes one of the sorting control codes recorded in the memory 26 it is entered into the actually addressed storing section of the memory 29. If, however, the data word represents a character information or a printing control code deter¬ mined for the sheet printer 1, it is entered into the actually addressed memory section of the memory 28. In the last mentioned case it is further examined whether the data word is the printing control code determined to release a "start printing" command in the sheet printer 1, said code being always transmitted at the end of the signal sequence pertaining to a deter¬ mined print page. If this is not the case the micropro¬ cessor 24 investigates whether the following memory sec- tion in each of the memories 28 and 29 is free, infor¬ mation in that respect being stored in the working memo¬ ry of the microprocessor 24. If the following section is free the memories 28 and 29 are addressed to enter the succeeding signal sequence into said section. If the following section contains character information and control codes for a print page that has not yet been fully printed a busy signal is transmitted to the data or word processing system 5. As soon as all character information and printing control codes for a full printed page have been record¬ ed in the corresponding memory section of the memory 28, the microprocessor 24 investigates whether the printer 1 is carrying out a printing job. Said investigation may be effected by a condition signal transmitted directly to the microprocessor 24 from the sheet printer 1 or by the control signal transmitted from the sheet sensor 21 upon arrival of a sheet in the slit 8. If the printer 1 is free, character information and printing control codes for printing the succeeding print page are trans- mitted from the memory section concerned into the memory 28 to the printer 1. Said transmission of character in- formation and printing control codes from a memory sec¬ tion in the buffer memory 28 to the printer 1 does, however, not cause erasing of the memory section. As explained in the following the character information and printing control codes for a print, page are in most cases recorded in the memory section concerned of the memory 28 until the microprocessor 24 has ascertained that printing as well as sheet sorting of the printed page concerned have been correctly effected. It is thereby made possible to repeat the printing of a page lost due to paper jam in the sorting apparatus, the necessary character information and printing control codes being immediately available in the memory 28. Said recording of character information and printing control codes further implies that repeated utilization of the information contained in a determined memory section provides for preparing more copies of a printed page also by a sheet printer that is not per se provided with a multicopy function. However, in the above specified situation where the required information for a print page occupies more than one memory section of the memory 28 as is the case with graphics it might be necessary to effect erasing immediately in connection with the transmission of information to the sheet printer 1. The flow diagram in Fig. 4 illustrates the above specified functional cooperation between the sorting apparatus and the sheet printer 1. Information about occupancy and release of the individual memory sections in the storage 28 is current¬ ly entered into the working memory of the microproces¬ sor. If there is at least one filled section in the me¬ mory, the microprocessor 24 investigates, as mentioned above, whether the sheet printer 1 is free and, if so, the information from the addressed memory section is transmitted to the sheet printer 1. As regards a single user system in which the printer 1 and the sorting apparatus 7 only serve a single data or word processing system 5, for instance a display terminal, the sorting control words stored in the memory 26 may for instance represent the three fol¬ lowing sorting functions. a. Selection of sorting bin in case of single-co¬ pying. b. Selection of sorting bin in case of multi-co- pying discharging the copies to the same bin. c. Multi-copying with sheet sorting in different bins. In a ROM-memory 30 of the micro-processor 24 there is, as regards each individual of said sorting functions, stored all needed control information for the actuation devices 15 of the guide means 14 and the • driving motor 20 connected with sorting trays. Execution of a given sorting function for a print page is started when the micro-processor 24, after a section 28a 28n of the memory 28 has been emptied to the printer 1, receives a control signal from the first sheet sensor 21 located at the sheet supply slit 8, said sensor being for instance a reflective photo-electric sensor, indicating the presence of a sheet with the printed page concerned at the supply slit 8. Upon starting the sorting function the micropro¬ cessor 24 reads the sorting control code in the corres¬ ponding section of the memory 29 and then effects the individual operations pertaining to the corresponding sorting function on the basis of the information of the function concerned contained in. the memory 30. As the first operation an activation signal is transmitted to the motor 20, thereby conveying the sheet supplied to the sorting apparatus 7 along the feeding path deter¬ mined by the pairs of feed rollers. The activation devi- ces 15, constituted e.g. by solenoids, of the individual sorting bins are subsequently actuated in dependence on the selected sorting function. In the above mentioned sorting functions a and b the supplied sheet will thus be guided to the selected sorting bin, while the acti¬ vation devices 15, in case of multi-copying of a printed page with sheet sorting, will be actuated consecutively to supply a single copy to each of a number of sorting bins in the sorting apparatus 7, corresponding to the the ordered number of copies. The sheet sensor 22 is common to all of the sorting bins and comprises a light source 22a and a photo-electric sensor 22b located above and beneath the pile of sorting bins 13, respectively, at their inlet end, all bins comprising in alignment with the radiation path between the light source 22a and the sensor 22b apertures 22c for the light passage. In this embodiment the sheet sensor 22 emits a control signal any time a sheet is correctly led into one of the sorting bins 13. Thereby, the microprocessor 24 is adapted to determine the time interval between control signals from the sheet sensors 21 and 22 by means of a clock generator 31 and to transmit an alarm signal to the alarm indicator 23 as a sign of paper jam in the sorting apparatus, if said time interval exceeds a determined period, about which information is recorded in the memory 30. In case of single-copying, the microprocessor 24 emits immediately upon correct receipt of the control signal from the sheet sensor 22 within the said time interval a signal for erasing the memory section con¬ cerned in the memory 28. In case of multi-copying the same printed page said erasing signal is, however, only emitted when the ordered number of copies has been led into the same tray or respective ones of the sorting trays 13. As mentioned above, said postponement of the erasing operation may, however, be selectively inacti- vated with a view to a quicker release of memory sec¬ tions in the memory 28 when the information pertaining to a printed page, e.g. in case of graphics, occupies more than one memory section. In the general case where character information and printing control codes for the printed page concerned is kept stored in the correspond¬ ing memory section of the memory 28 until the erasing signal is emitted in response to a control signal from the sensor 22 it will be possible at the occurrence of paper jam in the sorting apparatus 7 to restart very fast the printing of the ordered page after removal of the paper jam, the necessary character information and printing control codes being immediately available in storage 28. The flow diagram in Fig. 5 illustrates the above specified execution of a sorting function, the last mentioned possibility of inactivating said post¬ ponement of the erasing operatipn- being illustrated in a dashed line. As illustrated in the figures, the sheet sorting apparatus according to the invention may also be appli¬ cable to a multi-user system in which the sheet printer 1 besides the data or word processing system 5 shown in Fig. 1 as a display terminal serves a number of further systems 5a, b and c of the same kind from which charact¬ er information and control codes are transmitted to the control unit 16 of the sorting apparats 7 via individual cable connections 17a, b and c. In such a multi-user system the control unit 16 includes for each user system concerned, a memory 28-1, 28-2 and 28-3 corresponding to the memory 28 of character information and printing con¬ trol codes as well as a separate memory corresponding to the memory 29 of sorting control codes. In a normal working condition of the sorting apparatus a group of determined sorting bins out of the total number of sorting trays 13 may be allocated to each of the user systems 5-5c. Due to the above described structure and mode of operation of the sorting apparatus all of the user sy¬ stems can work simultaneously on the sheet printer 1 and the sorting apparatus 7 which, however, causes a propor- tional reduction of the printing speed compared to the normal working velocity of the sheet printer 1. The microprocessor may, however, be adapted to give on demand to a single user device a preferential position with free disposal of all sorting bins, thereby simultaneously blocking for printing from the other user devices. Particularly, when practising such a multi-user system it is an essential advantage if each of the sort¬ ing bins 13, as illustrated in Fig. 1, is provided with a sensor 32 adapted to detect the presence of fully printed sheets and to emit ' a control signal in case o ' f a fully empty or completely filled sorting bin, respec¬ tively. Thereby, the execution of a sorting function may be inactivated both when a bin selected to collect sheets is not fully empty when the printing starts or if the tray is overfilled. In a multi-user system with allocation of a group of bins to each user an automati¬ cal change to another bin intended for the same user may be effected in case of overfilling.

Claims: PATENT CLAIMS 1. A sheet sorting apparatus for an electronical¬ ly controlled sheet printer (1) in connection with a data or word processing system (5) from which character information and printing control codes are transmitted to the sheet printer (1) by signal sequences each of which contains all symbol information and printing con¬ trol codes for one page to be printed, said sheet sort¬ ing apparatus comprising preferably superposed sorting bins (13) with individual, selectively operable sheet guide means (14) adapted to feed a sheet to an arbitrary bin (13), characterized in that the sheet sorting appa¬ ratus is formed as a supplementary unit (7) having a sheet supply slit (8) to receive sheets from a discharge slit (2) of the sheet printer (1) and comprising a control unit (16) to be connected into the character in¬ formation connection-between the data or word processing system (5) and the sheet printer (1), said control unit (16) being adapted to separate in each transmitted signal sequence a sorting control code applied by the data or word processing system and being connected to said sheet guide means (14) and a driving motor (20) for sheet feeding means (9 to 12) in the sorting apparatus for the control thereof on the basis of the separated sorting control code and a control signal supplied to the control unit (16) from a first sheet sensor (21) located at the sheet supply slit (8). 2. A sheet sorting apparatus as claimed in claim 1, characterized in that the control unit (16) comprises a microprocessor (24) having means for comparing the information supplied from the data or word processing * system (5) to a number of prescribed sorting control codes and a storage (30) containing control information for executing sorting functions in response to the con- trol signal from said first sheet sensor (21) and in dependence on a sorting control code separated by said comparison. 3. A sheet sorting apparatus as claimed in claim 2, characterized in that the control unit (11) further includes a buffer memory (28) divided into a number of memory sections (28a 28n) which individually receive and store all the character information and printing control codes pertaining to a determined page to be printed before they are transmitted to the sheet printer (1) . 4. A sheet sorting apparatus as claimed in claim 2 or 3, characterized in that it further includes a second sheet sensor (22) located in connection with the sorting trays (13) for emitting a control signal upon correct supply of a sheet to an arbitrary bin (13). 5. A sheet sorting apparatus as claimed in claim 4, characterized in that said second sheet sensor (22) is constituted by a photo-electric sensor device common to all of the sorting bins (13) and disposed at the inlet end of the sorting bins (13) so that the radiation path from a light source (22a) to a photo-detector (22b) located at the opposite side of the pile of sorting bins (13) extends substantially perpendicular to the sorting trays (13). 6. A sheet sorting apparatus as claimed in claim 4 or 5, characterized in that the microprocessor (24) is programmed to record the time interval between a control signal from said first sheet sensor (21) and a success¬ ive control signal from said second sheet sensor (22) and to emit an error signal if said time interval exceeds a determined period of time. 7. A sheet sorting apparatus as claimed in any of the preceding claims, characterized in that it comprises inputs for standard signal transmitting cables (17 to 17c) from a number of user devices (5 to 5c) and that the microprocessor (24) in a normal working condition is programmed to allocate a number of definite sorting bins with each of said user devices (5 to 5c) . 8. A sheet sorting apparatus as claimed in claim 7, characterized in that the microprocessor in response to a demand control code from a user device (5 to 5c) is programmed to increase the number of sorting bins accessible to the user device and to processing such demand control codes in priority order. 9. A sheet sorting apparatus as claimed in any of the preceding claims, characterized in that a sensor (32) adapted to detect the presence of sheets in the tray is provided for each of the sorting trays (13).

Inventors: HYLTOFT HANS CHRISTIAN, NIELSEN BENT FROEHLKE, HYLTOFT, HANS, CHRISTIAN, NIELSEN, BENT, FROEHLKE
Applicants: BENT FROEHLKE NIELSEN APS, MERCANTE INT AS, MERCANTE INTERNATIONAL A/S
Application year: 1985
Main classification: B41J13
IPC codes: B07C3, B07C5, B65H39