Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F33/00—Indicating, counting, warning, control or safety devices
  • B41F33/04—Tripping devices or stop-motions
  • B41F33/14—Automatic control of tripping devices by feelers, photoelectric devices, pneumatic devices, or other detectors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F13/00—Common details of rotary presses or machines
  • B41F13/02—Conveying or guiding webs through presses or machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
  • B41J13/0009—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets control of the transport of the copy material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
  • B41J3/60—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for printing on both faces of the printing material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H2513/00—Dynamic entities; Timing aspects
  • B65H2513/10—Speed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H2513/00—Dynamic entities; Timing aspects
  • B65H2513/20—Acceleration or deceleration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
  • B65H2557/20—Calculating means; Controlling methods
  • B65H2557/24—Calculating methods; Mathematic models
  • B65H2557/242—Calculating methods; Mathematic models involving a particular data profile or curve
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H2801/00—Application field
  • B65H2801/03—Image reproduction devices
  • B65H2801/06—Office-type machines, e.g. photocopiers

Definitions

• the invention relates to a method of transporting sheets in a digital printing machine, wherein an individual sheet, preferably each sheet, is brought from a first transport speed to a second transport speed, preferably for transfer from one segment of the transport path to another segment of the transport path, said sheet experiencing at least one speed change (positive and/or negative acceleration).
• a method of the aforementioned type has basically been known from US 6 533 264 B1. With this method, a pre-specified distance between two successive sheets, for example in a copier or printer, is to be set. As a result, a uniform distribution of the sheets as well as a uniform utilization of the printing machine capacity are to be achieved.
• the object of the invention is to provide a method of the aforementioned type permitting an improved processing of print jobs involving recto-printing and verso-printing, specifically also when sheets having different weights, thus exhibiting different running times in the transport path, are used.
• this object is achieved in that, in order to process sets of sheets in batches by recto-printing and verso-printing (duplex printing), the sheets are fed to a transport loop of a transport path in order to pass, before and after a side-reversing inverting for printing, at least one printing unit, that the transport loop can be loaded with a natural number (n e N) of sheets, said number being a function of the format of the sheets to be processed, whereby the transport loop (virtually) is divided into a corresponding number (n) of loading fields (frames) for the sheets, and that the individual sheet in this transport loop is essentially negatively accelerated for the length of a corresponding transport path segment, preferably before passing the minimum of one printing unit, and is essentially positively accelerated for the length of a corresponding transport path segment, preferably after passing said printing unit.
• the minimum of one printing unit is alternately fed one recto printing sheet and then, again, one verso printing sheet.
• This process requires a rather complex coordination, because, for example, it may happen more frequently that, in the course of one print job, one or the other type of printing creates longer breaks because many successive sheets are to be printed in recto mode only ⁇ or every sheet is to be printed also in verso mode, which may certainly result in a situation in which, considering individual sheets, only the rear side is to be printed, i.e., only verso-printing without recto-printing is supposed to occur.
• the print job which potentially is also to be bound sorted, can be mixed up significantly and the minimum of one printing unit is most likely not optimally utilized, despite complex time management.
• the sheets of a print job are processed in batches; this means, sheets that are to be verso-printed are turned over in a greater number and again fed to the minimum of one printing unit and, in so doing, "interleaved" with batches of sheets that are still being recto-printed or "added on” to previous batches.
• sets (batches) of sheets alternate as they pass the printing unit. This causes specifically two problems.
• the transport loop must be divided into a positive whole number, for example 18, of imaginary or virtual fields or frames in order to accommodate exactly one pre-specified batch of sheets.
• the field size, and thus the number of fields potentially accommodated in the transport loop, is a function of the respective format of the sheets. In so doing, less deviating formats such as, e.g., DIN A3 and DIN A3+ do not result in a change of field size but the field is measured to have a size that will still accommodate the largest sheet of this format but that, considering a sheet having a format of, e.g., DIN A4, the field size can be reduced to half and the number of fields can be doubled.
• the second problem is that, in particular two successive batches must follow each other positioned correctly (registered).
• a first transport path segment that starts at the feeding units may consist for example of rotating driven grip belts, between which sheets are transported. Thereafter, the sheets could be transferred to and placed onto a rotating driven transport belt and adhere there due to electrostatic forces.
• this transport belt is a transparent web of plastic material and passes through a printing system, which, for color printing, may of course comprise several printing units.
• electrophotographic printing one latent toner image per color separation is transferred to the sheet. Thereafter, the sheet is transported to a fusing unit, in which the toner image is fused to the printing material, specifically melt-deposited there, and cooled. Considering the transport into and through the fixing unit, a change of the transport member could again occur.
• sheets to be printed on one side are then continued to be transported or ejected into a tray.
• sheets to be printed on both sides are returned to pass the printing unit and are turned over via a transport path loop for continued printing.
• the reverse transport and the turn may take place at the same time, for example, in that, also on this transport path segment, grip belts are used which take an approximately helical course and, in so doing, rotate the sheets about their longitudinal axes (pointing in the transport direction) by 180 degrees.
• the transport belt passing through the printing system and being frequently referred to as a web in electrophotography is to be loaded with sheets to be printed, whereby the space between sheets is to be small enough to achieve the greatest possible throughput per unit of time, i.e., ensure the highest possible printing output.
• minimum distances between successive sheets must be maintained. This applies to simplex-printing of only the front side of sheets, as well as to duplex-printing when the front and rear sides of the sheets are printed and perfected.
• the web is divided virtually, or also by means of controllers, into areas which can be described as frames, in which respectively one sheet - taking into consideration common formats - is to be precisely placed for printing.
• an area of the web is recessed, said area optionally having a transverse seam, by means of which the ends of the web are connected in order to form a closed loop.
• this seam is also used as a mark that is detected by a sensor in order to allow a control of the rotary position of the web and to have a reference point. Therefore, this seam must not be covered by a sheet.
• other marks could also be taken into consideration, in particular those which are applied only along the edge of the web.
• the ratio of the running time of the sheets rotating via the return after the first side has been printed with respect to the running time of the web must represent a whole number.
• problems may still occur in that sheet running times inside the considered printing machine are affected by various parameters. For example, the weight of the paper and the length of the paper have been found to represent dominant paper variables. Likewise, machine-specific parameters such as, for example, exact transport path length, roller diameter and motor speeds are contributing factors.
• the cited DE-A- 102 34 629 suggests that a starting time for feeding a sheet from any, or the only, feeding unit is chosen with respect to the type of printing material of which said sheet consists.
• sheets are started depending on their type - specifically their length and/or weight - at different times, i.e., fed by the respective feeding unit to the transport path, in order to apply a counter-error to potentially (even with respect to each other) wrong positioned sheets as expected during transport for correction at the onset, so that the desired position will be taken during transport.
• a modification in this case provides that information for the selection of the starting time is yielded beforehand by at least one trial run with at least one type of printing material, preferably by trial runs with different types of material, while a corresponding empirical table is created, for example, configured as a lookup table, i.e., a specified table.
• another modification of the inventive method advantageously provides that, during the essentially positive acceleration, the sheet is initially subjected to a negative deceleration from a first transport speed (V 1 ) to a (slightly) lower speed (v m ⁇ n ), then subjected to a positive acceleration to a high speed (v max ), and only then brought to the second transport speed (v 2 ), said second transport speed being (slightly) lower than the high transport speed (v max ) but (distinctly) higher than the first transport speed (V 1 ), whereby the positive acceleration from the lower speed (v min ) to the high speed (v max ) is chronologically shifted as needed, and/or that, during the essentially negative acceleration, the sheet is initially subjected to a positive acceleration from the second transport speed (v 2 ) to the high speed (v max ), then negatively subjected to a negative acceleration to the lower speed (v m i n ), and only then brought to the second transport speed (v 2 ), whereby the negative acceleration from the
• Another modification of the invention provides that, in order to detect the time of arrival of an edge of a sheet, specifically the lead edge and/or the rear edge of the sheet, in a pre-speci- fied position, an edge sensor is provided and that, based on this detection, a comparison of this position of the sheet with a desired position of the sheet to be assumed at this point in time is to take place, and that the velocity control is based on this. For example, based on this, the exact time of arrival of the lead edge of a respective sheet at the beginning of the acceleration segment can be determined, when - considering this acceleration - said sheet's rear edge is cleared, and/or when said sheet's lead edge or rear edge reaches the end of this acceleration segment.
• a precisely controllable high-performance stepper motor is used for the accelerations.
• a path segment between successive transport members, specifically pairs of rollers, of the transport path is used.
• An edge sensor is placed preferably at the start of said path segment.
• Independent protection is requested for a further modification of a method of transporting sheets iaa digital printing machine, whereby a single sheet, preferably each sheet, is brought from a first transport speed to a second transport speed, preferably for transfer from one segment of the transport path to another segment of the transport path, said sheet experiencing at least one speed change (positive and/or negative acceleration), said method independently achieving the object and being characterized in that a counted clock pulse reflecting the position of loading fields (frames), into which a transport loop for sheets is (imaginarily) divided, is generated, and that, based on this, the insofar absolute position of the sheet, i.e., the position of the sheet being a direct function of the positions of the previous and subsequent sheets, is determined with respect to at least one loading field, and that this position is used for a comparison with a desired position of this sheet, preferably with respect to the said loading field.
• a counted clock pulse reflecting the position of loading fields (frames), into which a transport loop for sheets is (imaginarily)
• the inventive method permits, in an especially advantageous manner, a precise positioning of sheets for batch mode, without encountering the above-described problems.
• the space potentially required for marks, specifically register marks, on a transport element (web) for sheets is available.
• the invention provides in particular the advantage that sheets can be fed directly by at least one feeder to a duplex turning loop configured as a transport loop for recto-printing and verso-printing, independent of whether the respective sheet is actually to be printed in recto- printing mode and verso-printing mode or only in recto-printing mode or verso-printing mode.
• a duplex turning loop configured as a transport loop for recto-printing and verso-printing, independent of whether the respective sheet is actually to be printed in recto- printing mode and verso-printing mode or only in recto-printing mode or verso-printing mode.
• independent protection is claimed for a device for transporting sheets in a digital printing machine, said device being used for bringing a single sheet, preferably each sheet, from a first transport speed to a second transport speed, preferably for transfer from one segment of the transport path to a another segment of the transport path, said sheet experiencing at least one speed change (positive and/or negative acceleration), preferably for carrying out the described method, said device independently achieving the object and being characterized in that, in order to process sets (batches) of sheets in recto-printing mode and in verso-printing mode (duplex), a transport loop of a transport path is provided, in which the sheets pass at least one printing unit before and after a side-reversing turn for printing, that the transport loop can be loaded with a natural number (n e N) of sheets which is a function of the format of the sheets to be processed, whereby the transport loop (virtually) is divided into a corresponding number (n) of loading fields (frames) for the sheets, and that the individual sheet in this transport loop
• the invention also relates to a method for transporting a sheet, in particular after a sheet has been picked off a stack and separated, preferable for the feeder-side use in a printing machine, with said sheet being held by a transport element, preferably a transport belt configured as a suction belt, and brought to a transport speed, preferably for transfer to another transport path.
• a transport element preferably a transport belt configured as a suction belt
• the invention relates to a device for transporting a sheet, in particular after a sheet has been picked off a stack and separated, preferably for the feeder-side use in a printing machine, said device comprising a transport element, preferably a transport belt configured as a suction belt, for holding the respective sheet and for bringing the sheet to a transport speed, as well as, preferably, for transferring said sheet to another transport path in order to carry out the aforementioned method.
• a transport element preferably a transport belt configured as a suction belt
• a method and a device of the aforementioned type have been known, in principle, from document DE 196 07 826 A1 , corresponding to document US 5 634 634 A. Specifically (see DE 196 07 826 A1 , column 10, lines 22 through 60), a clutch is selectively actuated to couple a motor with a roller set in such a manner that the transport belts are driven such that the grasped sheet is transported off a stack of sheets and is then ready for further processing.
• a clutch is selectively actuated to couple a motor with a roller set in such a manner that the transport belts are driven such that the grasped sheet is transported off a stack of sheets and is then ready for further processing.
• the object of the invention is to provide a controlled method of the aforementioned type and a device which permits the use of this method, in particular, considering sheets having a larger size and/or weight per unit area.
• this object is achieved, in so far as the method is concerned, in that the sheet is continuously accelerated from the sto'pped state to the transport speed.
• a modification of the inventive method provides that the velocity profile of the transport element essentially comprises three time phases, i.e., a first phase, namely the so-called acceleration phase of continuous acceleration from the stopped state to the transport speed, a second phase, which is the essentially constant transport speed, and a third phase, which is the reduction of the transport speed back to the stopped state.
• a first phase namely the so-called acceleration phase of continuous acceleration from the stopped state to the transport speed
• a second phase which is the essentially constant transport speed
• a third phase which is the reduction of the transport speed back to the stopped state.
• the progress of acceleration or the velocity profile plays a part in a problem-free acceleration of a sheet during the acceleration phase.
• another modification provides that the acceleration profile, during acceleration from the stopped state to the transport speed as a function of time (t), follows substantially a function sin x t, where the exponent x represents a number that is greater than or equal to 1 to smaller than or equal to 4.
• exponent x is approximately equal to 2.
• the speed reduction profile of the reduction during the third phase from the transport speed to the stopped state as a function of time (t) follows essentially a function sin x t, where the exponent x represents a number that is greater than or equal to 1 to less than or equal to 4.
• the negative acceleration profile of speed reduction can also be steeper than during the positive acceleration of the first phase, so that, preferably, in this case the exponent x may be approximately equal to 4.
• Another modification of the inventive method provides that the acceleration profile representing the acceleration from the stopped state to the transport speed is computed and stored, or otherwise recorded, before transport of the sheets, so that during the actual operation, no additional time-critical interventions are necessary during the operating cycle.
• the velocity profile is controlled electronically.
• the acceleration profile is preferably stored in electronic control means.
• an inventive device for transporting a sheet, in particular for picking a sheet off a stack and separating said sheet, preferably for the feeder- side arrangement in a printing machine, said device comprising a transport element, preferably a transport belt configured as a suction belt, for holding the respective sheet and for bringing said sheet to a transport speed, as well as, preferably, for transferring said sheet to another transport path, in order to carry out the aforementioned method, said method being characterized in that the transport element can be driven in such a manner that it can be continuously accelerated from the stopped state to the transport speed.
• the inventive device preferably comprises a (delivery) motor for driving the transport element.
• this delivery motor is a high-performance stepper motor.
• Fig. 1 a schematic side elevation of a part of a digital printing machine for carrying out the inventive method
• FIG. 2 through 9 velocity profiles, respectively showing the velocity v of a sheet as a function of time t,
• Fig. 10 a side elevation of an inventive device
• Fig. 11 a velocity and acceleration profile for carrying out the inventive method as a function of time (t).
• Fig. 1 shows a schematic side ⁇ elevation of a part of a printing machine for carrying out the inventive method.
• a feeder 1 for sheets of printing material a feeding segment 2 for sheets of printing material from said feeder 1 , in which case also more than one feeder may be provided, and a pocket 3 for sheets of printing material, in which case an output segment 14 leads to said pocket.
• the main part of a transport path for sheets of printing material consists of a duplex turning loop 5, which represents a segment of the transport path, the turning operation being symbolically indicated by bent arrows 16.
• An integral part of this duplex turning loop 5 is a closed rotating transport belt 4, which, in particular, moves the sheets of printing material past printing units 15 in order for said sheets to be printed.
• Sheets 7 and 8 are already on transport belt 4.
• Sheets 6 and 9 are in the duplex turning loop 5 and are either just leaving feeder 1 or have already been passed by printing units 15 and been turned over in zone 16. Within a short time, they will (optionally again) move onto transport belt 4.
• Sheets 10 and 11 have already again left transport belt 4 and/or duplex turning loop 5 and are on their way to pocket 3.
• the arriving sheets 6, 9 are fed in a timed manner to transport belt 4 as sheets 7, 8, for example, in such a manner that the printing machine is used in the optimal possible manner, in particular when one printing unit or several color printing units 15 are used optimally.
• sheets 6, 9 are (again) fed to transport belt 4 when said sheets have passed through the duplex turning loop 5 in order to now be printed (after their front sides have been printed or not) on their rear sides by printing units 15.
• a sheet 6, 9 can again be detected by lead edge sensor 13.
• the circulating time of sheet 6, 9 from lead edge sensor 13 via transport belt 4 into duplex turning loop 5 and through the latter back to lead edge sensor 13 is known, so that, during the first pass of a sheet through printing units 15, the sheet's return for printing its rear side could already be planned with respect to time, because, in particular, it is already known during the first pass by lead edge sensor 13 whether the just detected sheet 6, 9 is to be printed in simplex mode or in duplex mode.
• sheets having different weights exhibit different running time behavior in turning loop 5 and that sheets 6, 9, respectively, are to be batch-processed, in which case the number of sheets 6, 9, indicated here only as an example and sporadically for the sake of clarity, in a batch is such that the sheets of the batch just fill the turning loop 5, and that successive batches are to follow in registered position. Therefore, for potential skew correction in accordance with the invention, sheets 6, 7, 8, 9 experience two velocity changes in the duplex turning loop, i.e., at the sites indicated by dashed arrows 19 and 20, which is respectively downstream of turn 16 and upstream of lead edge sensor 13. Transport path segments exhibiting different speeds, for example, make sense even without skew correction in order to be able to feed sheets from feeder 1 at high speed into turning loop 5, for example, and be able to print, with printing units 15, at a relatively low process speed.
• an individual sheet 6 through 9 is accelerated by so-called "velocity ramps" 17, 18 indicated in Fig. 1 schematically by enlarged details in lined boxes, i.e., the sheet is brought in region 19 by ramp 17, essentially positively, to a higher speed and in region 20 by ramp 18, essentially negatively (decelerating), to a lower speed.
• ramps 17, 18 schematic side elevations of transport roller pairs are indicated as circles which may form parts of the transport path in the duplex turning loop 5. Between these transport roller pairs, velocity profiles of the individual sheets are indicated, whereby it is assumed that, in upward direction, the velocity is plotted as a function of time toward the right.
• box 17 indicates a linear velocity increase and box 18 indicates a linear velocity decrease, this resulting in a triangular shape with the coordinate axes, reminding of the side elevation of a ramp.
• box 18 indicates a linear velocity increase and box 18 indicates a linear velocity decrease, this resulting in a triangular shape with the coordinate axes, reminding of the side elevation of a ramp.
• the starting time of the respective positive or negative acceleration may be shifted chronologically as needed, in which case the time interval available is the time during which the sheet is located in the intermediate space between the indicated transport roller pairs.
• the acceleration for an on-demand increase or decrease of one or the other transport path segment of the duplex turning loop 5, namely the segment from zone 19 to zone 20 or the segment from zone 20 and, again, to zone 19, is shifted with respect to time.
• a faster sheet can be maintained longer at the lower speed and a slower sheet can be maintained for a shorter time in order to achieve a skew correction in this manner.
• the inventive method preferably provide ⁇ that, during the essentially positive acceleration, the sheet initially is subjected to a negative deceleration from a first transport speed (V 1 ) to a (slightly) lower speed (v mm ), then subjected to a positive acceleration to a high speed (v max ), and only then brought to the second transport speed (v 2 ), said second transport speed being (slightly) lower than the high transport speed (v max ) but (distinctly) higher than the first transport speed (V 1 ), whereby the positive acceleration from the lower speed (v min ) to the high speed (v max ) is chronologically shifted as needed, and/or that, during the essentially negative acceleration, the sheet is initially subjected to a positive acceleration from the second transport speed (v 2 ) to the high speed (v max ), then subjected to a negative acceleration to the lower speed (v min ), and only then brought to the second transport speed (v 2 ), whereby the negative acceleration from the high speed (v max ) to the lower
• Figs. 2 through 5, as well as Figs. 6 through 9, show detailed velocity/time profiles, respectively in boxes 17 and 18, as indicated by a simple triangular shape.
• the velocity v is plotted as a function of time t (or a distance s).
• time intervals ⁇ t can be converted, respectively, into distance intervals ⁇ s between successive transport rollers, as indicated in part in Figs. 2 through 9.
• the total chronologically or quasi spatially possible shift region of the "ramps" between roller pairs said shift region being indicated by a double arrow in boxes 17, 18 in Fig. 1 , can be identified, in this context with a double arrow, as distance L in Figs. 2 through 9.
• Figs. 2 and 3 now show that a respective sheet could be accelerated simply linearly from a speed V 1 to a speed V 2 , whereby this acceleration could begin sooner (Fig. 2) or later (Fig. 3) in order to change the length ratio between the above-addressed transport path segments for faster or slower sheets as needed.
• the acceleration is somewhat more complex than shown by Figs. 2 and 3, namely as shown by Figs. 4 and 5.
• the sheet is initially subjected to a negative deceleration from a first transport speed (V 1 ) to a (slightly) lower speed (v min ), then subjected to a positive acceleration to a high speed (v max ), and only then brought to the second transport speed (v 2 ), said second transport speed being (slightly) lower than the high transport speed (v max ) but (distinctly) higher than the first transport speed (V 1 ), whereby the positive acceleration from the lower speed (v min ) to the high speed (v max ) is chronologically shifted in segment ⁇ S 2 as needed.
• This procedure allows better consideration of given requirements and, at the same time, of conditions regarding space and time.
• Figs. 6 through 9 show the corresponding relationships and procedures, essentially in reverse, for the essentially negative acceleration in zone 20.
• Figs. 6 and 7 again show a simple linear negative acceleration, which can be shifted with respect to time
• Figs. 8 and 9 again show a more complex, preferred procedure, which provides that, during the essentially negative acceleration, the sheet is initially subjected to a positive acceleration from the second transport speed (v 2 ) to the high speed (v max ), then negatively subjected to a negative acceleration to the lower speed (v min ), and only then brought to the second transport speed (v 2 ), whereby the negative acceleration from the high speed (v max ) to the lower speed (v min ) can be chronologically shifted as needed.
• Fig. 10 shows an outline of a highly schematic illustration of another inventive device, in side elevation.
• the device comprises a separating device 21 for lifting a sheet off a stack 22 and for separating said sheet, and for a first transport of the separated sheet into an (additional) transport path.
• the separating device 21 substantially comprises a transport belt 23, which is configured as a suction belt and is looped around driving rollers 24 and is designed for grasping a sheet lifted off stack 22 and for transporting said sheet in the direction of an arrow 25, and which comprises a suction chamber 26 for attracting a sheet to transport belt 23 and for holding said sheet during its transport by transport belt 23.
• At least one of the driving rollers 24 is permanently connected with a motor 27 by means of a clutch 28, said motor also driving a first pair of transport rollers 29 of a transport path following separating device 21.
• Said motor 27 is a high-performance stepper motor, which is activated by electronic control means 30. With the use of said electronic control means 30, motor 27 - following a pre-specified velocity profile, can be activated and operated. This will be explained in detail in conjunction with Fig. 11.
• the pair of transport rollers 29 is followed by another pair of transport rollers 31 , to which the sheet can be transferred. Apart from that, the further progress of the transport path is not illustrated in detail.
• a sensor - in viewing direction of an arrow 32 - is provided for sheet detection, whereby said sensor may also be connected with electronic control means 30 in order to detect the time of arrival of the trailing edge of said sheet.
• Fig. 11 shows a velocity and acceleration profile of the sheet, or motor 27, and transport belt 23 during transport through separating device 21.
• a solid line shows the profile of velocity v as a function of time t.
• a broken line shows the profile of the associate acceleration as a function of time t for the acceleration phase of the velocity profile.
• the velocity profile is divided into three phases. First, during an acceleration phase, acceleration occurs to a constant transport speed, then, during a second phase, this transport speed is maintained for a certain period of time, and finally, during a third reduction phase, the speed is again reduced to a stopped state.
• the illustrated acceleration during the first acceleration phase in so doing, follows a sin 2 (t) function.
• the reduction of speed during the third reduction phase may be significantly steeper; in this case, the (negative) acceleration could follow, for example, a sin 4 (t) function.
• the reduction phase could be started, in particular, when sensor 32 detects the trailing edge of the sheet, i.e., when the sheet leaves the inventive device.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Delivering By Means Of Belts And Rollers (AREA)
• Sheets, Magazines, And Separation Thereof (AREA)
• Handling Of Sheets (AREA)

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• 2006
  • 2006-04-13 WO PCT/EP2006/003415 patent/WO2006111322A2/en not_active Application Discontinuation
  • 2006-04-13 JP JP2008506978A patent/JP2008536718A/ja not_active Ceased
  • 2006-04-13 EP EP10156368A patent/EP2213463A3/de not_active Withdrawn
  • 2006-04-13 EP EP10156370A patent/EP2191972A3/de not_active Withdrawn
  • 2006-04-13 EP EP06724311A patent/EP1871610A2/de not_active Withdrawn

Patent Citations (7)

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