Abstract:
A method for detecting a copy jam or buildup in a folder uses sensors assigned to a copy transport path for determining a sequence of copies along the copy transport path. The sensors are formed of a transmitting part and a receiving part, and the method includes having the sensors release an input signal to a paper jam-detection device in response to the presence of copies detected by the receiving parts of the sensors. The input signal produces a counting pulse. A system for performing the method and a folder including the system are also provided.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a method and a device for detecting a true product jam in a folder. 
     Japanese Patent JP 5 26382 discloses a device for detecting a paper jam or buildup in a folder. In this heretoforeknown device from the state of the art, a sensor is disposed at a defined location in the folder along the copy transport path, and detects the presence of folded products transported along the path. When the results of the detection show that a paper jam or buildup is occurring at the aforementioned defined location, the rotary printing machine must be stopped. In the improvement in the art presented in this Japanese patent, a test mode is provided, wherein cutoff functions can be simulated, but the cutoff function which brings the rotary printing machine to a stop is blocked. It is thus possible to check whether or not a safety cutoff is functioning reliably as is required when a paper jam is detected in a folder downline of a rotary printing machine. Japanese Patent JP 5 26381 discloses a device for detecting a paper jam or buildup in a folder, wherein a sensor is likewise arranged at a defined location along the folded-copy transport path. The sensor detects the presence of copies transported along the path and, based upon the detection results, establishes that there is a paper jam at the respective location at which the sensor is integrated into the transport path of the copies. Care is taken to ensure that, when the power source is applied, different signals are emitted in a case wherein the sensor is connected to the main circuit and in a case wherein the sensor is separated from the main circuit. 
     Finally, Japanese Patent JP 5 26379 discloses a further device for locating a paper jam or buildup in a folder. This device is equipped with sensors which are likewise arranged at defined locations, in order to detect the presence of copies transported along the folded-copy transport path. Facilities are provided for deciding whether or not, based upon the results of detection by the sensors, there is a paper jam at the respective location. Furthermore, indicators are provided for indicating a paper jam, based upon the decision of the aforementioned decision-making facilities. The indicators include memories which maintain the indication of a paper jam and which, when a paper jam is present, cause only that location to appear on an indicator at which a paper jam was first indicated as being present by the aforementioned decision-making facilities. 
     In copy-processing machines, for example, a rotary printing machine with a downline folder, copy jam or buildup detection is based upon an evaluation of the number of cutting-cylinder revolutions, and an evaluation of the copies seen and correspondingly counted along the copy transport path by the sensor cells. When detached paper shreds or copy fragments move through the folder, which may be swirled around by airflows, these may falsely suggest the occurrence of a copy jam or buildup, even though no copy jam or buildup exists This may be due to the fact that the paper shreds cover a sensor cell in such a way that the sensor cell can no longer reliably count the folded copies passing per unit time. In individual instances, detached pieces of paper or paper shreds have been counted as intact copies by the sensor technology within a folder. A comparison of the counted copies with the copies actually counted off from the incoming material web by the pair of cutting cylinders has led to implausible results. 
     SUMMARY OF THE INVENTION 
     In view of the prior art outlined it is accordingly an object of the invention to provide a device for detecting a true product jam or build-up in a folder and, more particularly, sensor technology for ensuring a correct indication of a copy jam or buildup. 
     With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for detecting a copy jam or buildup in a folder, by sensors assigned to a copy transport path for determining a sequence of copies along the copy transport path, the sensors, respectively, being formed of a transmitting part and a receiving part, which comprises having the sensors release an input signal to a paper jam-detection device, in response to the presence of copies detected by the receiving parts of the sensors; and having the input signal produce a counting pulse. 
     In accordance with another mode, the method of the invention includes providing the paper jam-detection system with inverting inputs for triggering the counting pulse when there is no voltage at the receiving parts. 
     In accordance with a further mode, the method of the invention includes continuously sensing the edge regions of the copies with the sensors. 
     In accordance with an added mode, the method of the invention includes comparing the number of revolutions of a cutting-cylinder pair with the number of copies passing the sensors for determining a paper jam in the folder. 
     In accordance with an additional mode, the method of the invention includes failing to release a counting pulse when the input signal at the paper jam-detection device is based upon a voltage signal from only one of the receiving parts. 
     In accordance with a further aspect of the invention, there is provided a system for detecting a copy jam in a folder by sensors assigned to a copy transport path for detecting a sequence of copies along the copy transport path, comprising a parallel-connected arrangement of the sensors wherein the sensors are assigned to edge regions of the copies, and serve simultaneously for sensing the copy transport path. 
     In accordance with an added feature of the system of the invention, the sensors, respectively, include both a transmitting part and a receiving part. 
     In accordance with an additional feature of the system of the invention, the sensors, respectively, are connected at one voltage level and have a live voltage-carrying output. 
     In accordance with yet another feature of the system of the invention, the voltage-carrying outputs are combined for generating an input signal to the paper jam-detection device. 
     In accordance with yet a further feature of the system of the invention, the receiving parts include switching elements and identical open contact positions for generating a counting pulse at the paper jam-detection device. 
     In accordance with yet an added feature of the invention, at least one closed contact on the receiving parts serves for generating an input signal which does not trigger a paper jam detection. 
     In accordance with a concomitant aspect of the invention, there is provided a folder with a copy transport path, along which copies are transported in a continuous sequence, and sensors assigned to the copy transport path, the sensors, respectively, including a transmitting and a receiving part, comprising at least one parallel-connected sensor pair arrangement provided along the copy transport path for sensing the copy transport path simultaneously with producing combinable output signals by the receiving parts of the sensor-pair arrangement. 
     Thus, by the further developments proposed in accordance with the invention, in the detection of a paper jam or buildup, a counting pulse is triggered only when both sensors indicate the presence of a folded or foldable copy to be transported. Paper shreds or detached product fragments are detected as such and, when they enter the field of detection of one of the sensors, do not generate a counting pulse in the paper jam or buildup detection-device. There is therefore no false indication of a paper jam or buildup; if one of the sensors of a sensor pair fails, the rotary printing machine can nevertheless continue to operate with minimal wiring changes, and the paper jam or buildup-detection device continues to be active. 
     If the paper jam or buildup-detection device has inverting inputs in order to increase redundancy, a counting pulse is triggered in the paper jam or buildup-detection device whenever there is no voltage at the receiving parts of the sensors of the sensor pair. In this case, both sensors of the respective pair see a folded or foldable copy, and this is detected as such and is counted correspondingly. The sensor pairs are oriented along the copy transport path in a manner that they preferably detect edge regions of the folded or foldable copies conveyed in rapid sequence and are arranged eccentrically with respect to the copy transport path. In order to detect a copy jam or buildup, the paper jam or buildup-detection device continuously compares the numbers of revolutions of the cutting-cylinder pair with the number of counted copies. 
     The sensors, respectively, include a transmitting and a receiving part. Radiation is emitted continuously from the transmitting part to the receiving part, and the two sensors of the sensor pair are connected in parallel. The sensors are at one voltage level and include electric contact elements which, when both sensors detect folded or foldable copies, remain open and trigger a counting pulse on the paper jam or buildup-detection device by inverted inputs thereat. Where a contact of one of the sensors of the sensor pair is closed, no counting pulse is generated, and the paper jam or buildup-detection device remains inactive. 
     The method according to the invention can be employed in folders both for newsprinting and for job printing, whether on folders with sets of pins or on folders operating without pins. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a method and device for detecting a true product jam or buildup in a folder, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
    
    
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic top plan view of a sensor device known from the prior art, which is disposed along a copy transport path; 
     FIG. 2 is a view like that of FIG. 1 of sensor devices arranged in parallel with one another for sensing edge regions of copies; 
     FIG. 3 is a schematic and diagrammatic view of transmitting and receiving parts of a conventional sensor device, which are connected to an evaluation unit; 
     FIG. 4 is a view like that of FIG. 3 of a sensor device according to the invention wherein signal indicators of two receiving parts are connected to the evaluation unit; 
     FIGS. 5 a ,  5   b  and  5   c  are respective fragmentary views of FIG.4 showing the sensor parts and receiving parts of the sensor pair in different contact states; and 
     FIG. 6 is a diagrammatic side elevational view of a folder having a pinless operation, with sensor pairs integrated in the copy transport path. 
    
    
     As noted hereinbefore, in the illustration according to FIG. 1, a configuration that has become known from the prior art is shown. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now specifically to the drawings, and particularly to FIG. 1 showing the device of the prior art, folded or foldable copies  4  and  5  are conveyed in a copy transport direction represented by the arrow  1 . Provided in a device which is somewhat central to a copy transport path  2  is a sensor  3  past which a counted copy  4  has been transported, followed by a further folded or foldable copy  5  which is yet to be counted. Whether the sensor  3  disposed centrally to the copy transport path  2  detects a folded or foldable copy, or a part thereof, a fragment or a paper shred as a copy cannot be stated with certainty, because no redundant capability for checking the signal determined by the sensor  3  is provided. 
     The sensor  3  generates a counting pulse even when the sensor  3  is covered or concealed by paper shreds; the addition of pulses obtained in this manner and the comparison thereof regularly leads to the situation wherein the counted pulses exceed the number of cutting-cylinder revolutions which indicate, respectively, that a folded or foldable copy has been detached from the incoming material web, and a paper jam or buildup is detected, even though no such paper jam or buildup is present. 
     In the configuration according to FIG. 2, a device according to the invention is provided which is formed of a sensor pair including the sensors  6  and  7  which are assigned, respectively, to edge regions  8  and  9  of the conveyed folded or foldable copies  4  and  5 . The sensors  6  and  7  are energized in parallel, and continuously and simultaneously sense the copy transport path  2  in the copy transport direction  1 . So that the sensor technology detects a folded or foldable copy as such, both sensors  6  and  7  must detect “paper” simultaneously, with the result that corresponding signals are generated for the paper jam or buildup-detection system  12  (note FIGS.  3  and  4 ). 
     In known sensor devices according to FIG. 3, the sensor  3 , disposed centrally in the copy transport path  2  and formed of a transmitting part  10  and a receiving part  11 , was energized permanently via supply lines  13 . Between the transmitting part  10  and the receiving part  11 , radiation  10 . 1  is exchanged, which indicates the detection of a folded or foldable copy, or implies the absence of a folded or foldable copy. 
     According to FIG. 4, the configuration according to the invention then includes two parallel-connected sensors  6  and  7 . The pairs of sensors may be arranged along the copy transport path  2  through a folder  23  (note FIG. 6) at the critical location along the copy transport path  2 , in particular at a pair of cutting cylinders  24  and at the transfer points of the cylinders guiding the folded or foldable copies. A sensor pair, formed of the sensors  6  and  7 , respectively, sensing two edge regions  8  and  9  of the folded or foldable copies  4  and  5 , is energized in parallel by a supply line  13 . Each of the sensors  6  and  7  is made up of a transmitting part  6 . 1  and  7 . 1 , respectively, and of a receiving part  6 . 2  and  7 . 2 , respectively. The detection of folded or foldable copies  4  and  5 , respectively, takes place without contact between the two by radiation exchange  10 . 1 . The output signals generated by the receiving part  6 . 2  or  7 . 2  of the respective sensor  6 ,  7  are combined and arrive as an input signal  15  corresponding to the combination at the paper jam or buildup-detection device  12 . The latter is activated only by the signal  15  combined from the output signals of both receiving parts  6 . 2  and  7 . 2 . 
     The paper jam or buildup-detection device  12  may either be provided with inverting inputs or else equipped with non-inverting inputs. 
     The manner in which the sensor pair functions is presented in greater detail in the illustration of the various contact states of the sensors  6  and  7 , shown in FIGS. 5 a ,  5   b  and  5   c.    
     The sensors  6  and  7  are connected at  18  to the 0V (zero voltage) level, and to a positive supply voltage +V at 19. 
     The sensors  6  and  7 , in particular on the respective receiving parts  6 . 2  and  7 . 2 , have electric contact elements  16  and  17  which can take on or assume an open or a closed state, respectively. In the state  20 , both contacts  16 , respectively, are open; the sensors  6  and  7  have both detected the presence of a folded or foldable copy  4 ,  5 . A corresponding signal is picked off at the outputs of the respective receiving parts  6 . 2  and  7 . 2  of the sensors  6  and  7 . This signal is transmitted as an input signal  15  to the paper jam or buildup-detection device  12 . If the input of the latter is constructed as an inverting input, then, because the respective contacts  16  of both sensors  6  and  7  are open, and therefore there is no output signal, a counting pulse is triggered due to the inversion at the input  15  of the paper jam or buildup-detection system  12 . 
     When the contacts  17  are closed in both sensors  6  and  7  according to the state  21 , then, presupposing that the inputs on the paper jam or buildup-detection device  12  are inverted, the output signal being inverted when applied, there is no counting pulse in the paper jam or buildup-detection device  12 . 
     According to the state identified by the reference numeral  22 , on the sensors  6 ,  7 , the contact elements  17  of a sensor  6  or  7 , (here the sensor  7 ), are closed. However, the contact elements  17  of the sensor  6  are open, so that, after the output signals from the sensors  6  and  7  are combined, a positive output signal appears at the signal input  15  of the paper jam or buildup-detection device  12 . This signal, inverted at the input of the paper jam or buildup-detection device  12 , does not give rise to any triggering of a paper jam or buildup-detection signal, because only one of the sensors  6  or  7  had detected the presence of “paper”, but not the opposite sensor. The triggering of a false paper jam or buildup detection by a paper shred or other object accidentally covering one of the sensors  6  or  7  is counteracted, with the result that the significant resulting circumstances occurring when a web-fed rotary printing machine is cut off can be avoided altogether and, in particular, the workload and therefore the productivity of web-fed rotary printing machines can be kept at the highest possible level. 
     In addition to the discussion of the inverting inputs of the paper jam or buildup-detection device  12  which was conducted in connection with the various states in FIGS. 5 a ,  5   b  and  5   c , the inputs thereof may also be connected positively. The further processing of the input signal  15  in the case of a positive connection of the paper jam or buildup-detection device  12  and the triggering of a counting pulse then take place correspondingly. 
     FIG. 6 is a diagrammatic reproduction of a folder with pinless operation. The folder  23  includes a plurality of sensor pairs  6 ,  7  disposed along the copy transport path  2 . In the illustration shown, the sensors  6  and  7  are arranged, in particular, at the cutting-cylinder pair  24 , and also along the transport belt train  25 . A further sensor pair  6 ,  7  is accommodated at an exit point downline of the transport belt train  25  before the transfer to the folding cylinder  26  of the copies  4  and  5 , which are to be folded. On the circumference of the paper-guiding cylinder  26 , the copies are conveyed in the direction of rotation  30  towards a point of transfer to a further paper-guiding cylinder  27 , namely, a folding jaw cylinder. A further sensor pair  6 ,  7  may be arranged, either above or below the copy transfer point, in the wedge between the cylinders  26  and  27  guiding the foldable copies, in order to monitor the copy transfer. A sensor pair  6 ,  7  may likewise be accommodated at the transfer point between the folding jaw cylinder  27  and a transport cylinder  28  arranged above the latter. 
     The number of detached folded or foldable copies  4  and  5  can be inferred directly from the number of revolutions of the cutting-cylinder pair  24 , and, in this regard, it is unimportant whether the cutting cylinder pair  24  is of the single-revolution or half-revolution type. From the conventional sensor positions along the copy transport path  2 , reliable evidence as to whether or not there is a copy jam or buildup in the folder  23  is obtainable for each of the positions of the sensors  6  and  7  by the copy number comparisons determined in the paper jam or buildup-detection device  12 .