GB2114339A - Improvements in or relating to devices for counting sheets in stacks of sheets - Google Patents

Abstract

A device for counting the number of sheets in a stack 9 comprises sheet separating assembly insertable between the sheets for separating each successive sheet in the stack. This sheet separating assembly has a bearing surface 4 for accommodating a sheet, a means 7 for carrying the sheet from one side to the other of the bearing surface past a counting station (14), e.g. employing a photo-electric device for counting the separated sheets and is provided with a slotted nozzle 5 communicating with a source 6 of compressed gas to produce a flat jet of gas directed along the bearing surface and such as to provide an underpressure in the proximity of the bearing surface to cause the sheets being separated from the stack of sheets to adjoin the bearing surface with a certain gap between the sheet and the bearing surface. Other embodiments (Figures 6-12) employ a rotating separator disc with the gas jet directed radially outwards in the region of a sheet separating finger (20). <IMAGE>

Description

SPECIFICATION Improvements in or relating to devices for counting sheets in stacks of sheets The present invention relates to devices for counting the number of paper sheets in stacks of sheets without removing the sheets from the stacks of sheets. Such a device may advantageously be used for counting valuable papers, as well as in printing houses, paper production factories and for other uses where a need for such paper counting may arise, for example, in trade and transportation.

According to the invention, there is provided a device for counting sheets in a stack of sheets, comprising a pneumatically operated sheet separating each successive sheet from the stack of sheets, the sheet separating assembly having a bearing surface for accommodating a sheet, means for carrying the sheet in a sheet registering position over the bearing surface, and a register connected to a sheet counter for counting the separated sheets, the sheet separating assembly and the stack of sheets being capable of relative displacement for separating successive sheets from the stack of sheets, the sheet separating assembly being provided with a slotted nozzle communicable with a source of compressed gas to produce a flat jet of gas directed lengthwise of the bearing surface, the pressure and the flow rate of gas in the jet of gas being selected so as to produce an underpressure in the proximity of the bearing surface to cause the sheet being separated from the stack of sheets to adjoin the bearing surface with a gap between the sheet and the bearing surface.

It is thus possible to provide a device for counting the number of sheets in a stack of sheets having a sufficiently simple and reliable construction, being capable of preventing damage to the sheets being counted, and being capable for use for counting various types of paper sheets.

An advantage of such a device is that the use in the sheet separating assembly of compressed gas for successive separation of sheets allows an air cushion effect to be used. A jet of compressed gas provides proper orientation of the sheet being counted relative to the sheet separating assembly with a gas gap, thereby preventing damage to the sheet being separated and wear of the sheet separating assembly due to friction. In addition, construction of the device is considerably simplified and reliability thereof is markedly improved by obviating the susceptibility of the device to clogging and wear of the working surface under the action of the outside medium.

In one preferred modification of the device for counting the number of sheets in a stack of sheets, the sheet separating assembly comprises a jet suction means executing the separation of sheets from the stack of sheets, and two movable axles provided for carrying the sheet being separated over the suction means along a predetermined path, the stack of counted sheets being secured in a clamp intended to orient the stack properly relative to the suction means. Registration of the number of separated sheets is effected by means of a sheet counter arranged to add signals received from a sensor attached under the jet suction means, the signals occurring each time a sheet being separated is carried over the suction means by the sheet separating axle.

In another embodirnent of the device for counting the number of sheets in a stack of sheets, sheet by sheet separation and registration of sheets separated from the stack of sheets being counted is effected by a disc member providing for separation and registration of sheets by means of compressed gas. Sheet separation is executed by a flow of compressed gas escaping from a nozzle in a radial direction between the plane of the disc member and the sheet being counted from the centre of the disc along the bearing surface of smooth concave shape, registration of the separated sheet being done by a pressure sensor having a pneumatic chamber and a hole wherethrough a jet of compressed gas is supplied into a space between the sheet separating tooth and a cover plate.The passage through this area of the separated sheet causes pressure variations in the pneumatic chamber which are registered by the pressure sensor and added by the sheet counter.

In another modified form of the device for counting sheets in a stack of sheets, the sheet separating assembly has the form of a disc member in the form of a truncated cone with a shaped recess defining a sheet separating tooth, the disc member having a bearing surface of smooth concave shape arranged on the base portion of the disc member and provided at the peripheral portion thereof with a through hole or slot communicating the bearing surface of the disc member with the tapered surface thereof, the sheet separating assembly further having fixedly arranged over the base of the disc member a nozzle connected to a pneumatic chamber having a hole, an ejector connected to a source of compressed gas, and a pressure sensor connected to a sheet counter.The device is fed from a source of compressed gas connected with the inlet of the ejector by a conduit, the diffuser of the ejector being connected to the nozzle, the pneumatic chamber being communicable with the pressure sensor and the mixing chamber of the ejector. Sheet separation from the stack of sheets is effected during interaction of the disc member, the jet of compressed gas and the sheets in the stack of sheets to be counted. The separated sheets are registered by the pressure sensor which senses a pressure differential in the pneumatic chamber disposed on the stationary nozzle during carrying of the separated sheets by the sheet separating tooth to the opposite side of the disc member, this pressure differential in the pneumatic chamber occurring due to the displacement of the sheets relative to the hole in the pneumatic chamber.The counter sums up signals received from the pressure sensor in the course of carrying the separated sheets to the opposite side of the disc member.

In yet another embodiment of the invention, the sheet separating assembly has the form of a flat disc the rotation of which may be reversed, the disc being provided with a radial slot and nozzles disposed on the two sides of the disc and communicable with a source of compressed gas, and two collars shaped in such a fashion as to be capable of entrapping a separated sheet and carry this sheet from one disc surface to the opposite one during any of the two directions of disc rntation.Such a construction of the sheet separating assembly allows sheets to be separated from any of the two sides of the stack of sheets thereby providing for multiple sheetcounting.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a sheet counting device constituting a preferred embodiment of the invention provided with a jet suction means for sheet separation and an endless belt or conveyor; Figure 2 shows the device of Figure 1 at the moment when a sheet is separated from a stack of sheets; Figure 3 shows the device of Figure 1 when the sheet is being carried over the suction means; Figure 4 shows the device of Figure 1 when the sheet is being moved on the other side of the jet suction means; FigureS shows the device of Figure 1 at the point of complete separation of the sheet from the stack of sheets; Figure 6 shows another embodiment of the device where use is made of compressed gas engaged periodically;; Figure 7 is a cross-section of the device of Figure 6 taken along the line VII-VII at a point when a sheet is being separated from the stack of sheets; Figure 8 is a cross-section of the device of Figure 6 taken along the line VIII-VIII at a point when the separated sheet passes a sheet counting position; Figure 9 shows a modified device consisting another preferred embodiment of the invention provided with a stationary nozzle; Figure 70 is a section of the device taken along the line X-X in Figure 9 illustrating the manner in which a sheet is separated from the stack of sheets; Figure 7 7 shows another device constituting a preferred embodiment ofthe invention employing a flat plate as the disc member;; Figure 12 is a section taken along the line XII-XII device in Figure 11 from the side of the radial slot; Figure 13 is a section of the device of Figure 11 taken along the line XIII-XIII at a point when a sheet is being separated from the stack of sheets; and Figure 14 is a section taken along the line XIV-XIV ofthe device of Figure 11.

As illustrated in Figures 1,2,3,4 and 5, the device comprises a sheet separating assembly which includes a flat plate and an endless belt or conveyor.

The device further comprises a clamp means for clamping a stack of sheets being counted, a register having a sheet counter, and a source of compressed gas.

The sheet clamp means serves to hold the stack of sheets being counted in a predetermined position relative to the sheet separating assembly The clamp means comprises upper and lower jaws 1 and 2 resiliently urged toward each other, capable of movement along a vertical axle 3 under the gravity of its own weight and the weight of the stack of sheets, and capable of swivelling about this axle.

The sheet separating assembly of the device comprises a smooth plate 4 along which a jet of compressed air from the compressed air source 6 is supplied through a nozzle 5 in the form of an essentially rectangular aperture. By selecting the pressure and flow rate of the gas excaping from the nozzle which may be determined mathematically but is normally found experimentally, an underpressure is produced between a sheet of paper and the plate to result in "jet suction" providing for separation of the sheet from the stack of sheets and holding the sheet to the plate. It should be noted that a thin film of gas is present between the surface of the plate and the sheet preventing a direct contact between the sheet and the plate, the endless belt or conveyor acting to put the sheet thus separated into a sheet registering position.

Separating and support axle 7 and 8, respectively, intended for displacing the sheet separated by jet suction from the stack of sheets 9 to the other side of the plate 4 are set in motion by chains 10 to which they are attached. In turn, the chains 10 are moved by sprockets 11 secured on a common shaft rotated by an electric motor 13 through a coupling 12. The movement of the chains around the sprockets and guide plates of predetermined configuration provides for a travel path of the separating and support axles 7 and 8 such as to minimize crumpling or folding of the sheets.A pick-up 14 for counting the number of sheets displaced to the other side of the jet suction plate is generally a photoelectric cell comprising, for example, a combination of a lightemitting diode and a photodiode arranged at an angle one relative to the other so that, during bending of the sheet around the edge of the jet suction plate overlying the pick-up, the light emitted by the light-emitting diode is reflected from the sheet and falls onto the photodiode. An amplified signal is transmitted to a counter 15 which adds it to the signals thus received.

The counting device described hereinbefore operates as follows.

A stack of sheets to be counted is placed between the upper and lower jaws 1 and 2 of the clamp means in a position of the clamp means swivelled away from the sheet separating assembly, as shown in Figure 1 by broken lines. Thereafter, the clamp means with the stack of sheets is swivelled to a working position for the stack of sheets to bear on the jet suction plate 4 of the sheet separating assembly. When the device is energized, the source of compressed gas and the pick-up with the counter become operational. Upon attaining a preselected pressure in the compressed gas source 6, an electropneumatic transducer 6' is actuated for the compressed gas to be supplied to the nozzle 5 from which it travels lengthwise of the plate 4.Orientation of the lowest sheet in the stack of sheets relative to the plate 4 is ensured by an aerodynamic effect produced by an underpressure caused by an in crease in the flow rate of gas fed into a space between the plate 4 and the stack 9 of sheets as has been mentioned earlier. Therefore, the sheet separated from the stack tends to suspend over the jet suction plate 4 to form between the sheets and the stack 9 a space whereinto the separating and support axles enter (Figure 2). The arrangement of the electropneumatic transducer 6' is followed by actuation of the electric motor 13 driving the endless chain 10 to set the axles in motion.Because the axles move along a path intersecting the thus formed space between the stack and the sheet, the travel of the axle 7 causes each separate sheet to be pulled over the jet suction plate 4 (Figure 3) which axle also acts to separate the sheets which have been counted from the sheets in the stack which are to be counted, whereas the support axle 8, while taking the weight of the stack, provides for a free passage of the separated sheet over the plate 4.

In order to increase the efficiency of the device, the chains providing the movement of the separating and support axles along a predetermined path may additionally have another pair of axles spaced a preselected distance one from another as indicated generally in Figure 4 by the asterisks 7 and 8. Figure 5 illustrates a position where the separated sheet is finally carried over the jet suction plate. When the stack of sheets has been counted, the electropneumatic transducer and the electric motor of the chain belt are disengaged and the stack is swivelled away from the sheet separating assembly to be removed from the clamping jaws.The number of sheets counted is indicated in the counter 15 which can execute a general count, as well as to count according to a predetermined program whereby the counter sends a signal to switch off the drive motor of the chain belt and the electropneumatic transducer, the number of sheets determined by the program therefor taking a position below the jet suction plate.

In order to provide for added reliability of the device, the plane of the jet suction plate 4 is disposed at an angle to the plane of the sheets contained in the stack, whereas the jet of compressed gas escaping from the slotted nozzle having a ratio between the sides thereof 1 to 16 is directed lengthwise of the plate surface towards the stack, the sheets of the stack overlapping the edge of the nozzle. Pressure and flow rate of compressed gas in the jet are selected so that an underpressure is produced in the area adjacent the plate causing the sheet being separated from the stack to stick to the plate with an air gap therebetween.

In the device for counting sheets in a stack of sheets as herein before described, the sheet separating assembly has the form of a generally stationary jet suction means with movable axles acting to displace the sheet being separated. An inherent advantage of such a device resides in that it can count decrepit items, such as used banknotes, coupons, blanks and the like.

With reference to Figure 6, there is shown another sheet separating assembly of a counting device in the form of a disc member having provision for a periodic engagement of compressed gas. The sheet separating assembly (Figures 6, 7 and 8) comprises a disc member 16, a gas distributer 17, and a cover plate 18. The disc member has the form of a truncated cone having a shaped recess 19 defining a sheet separating tooth element 20. The portion of the disc separated by the recess and facing the tooth element 20 is provided with a spirally extending concave bearing surface 21, the concavity of which increases toward the sheet separating tooth element 20. The lower side of the separating tooth element 20 accommodates an opening 22 opening at the base of the disc member 16. The gas distributor 17 is attached to the disc member 16 by screws 23.The upper face of the distributor 17 has an annular recess 24 and a through hole 25, the lower face thereof having two radially extending passages, particularly a passage 26 extending from the through hole 25 and a passage 27 extending from the annular recess 24. The gas distributor is affixed to the disc member in such a manner that the opening 22 communicates with the annular recess 24 by way of the passage 27, the passage 26 defining with the surface of the disc member a narrow slotted nozzle 28 disposed in front of the sheet separating tooth 20. The cover 18 is generally a thinwall plate conforming to the shape of the disc member is attached to the disc member in the zone of the shaped recess 19 to close in on the tapered side of the disc leaving, under the tooth, a space or gap 29 for a sheet being separated and counted to pass therethrough.For the sake of clarity Figures 6,7 and 8 do not show the source of compressed gas, disc drive means, counter with a pick-up or the sheet stack clamping means, since these elements may be embodied in any suitable conventional manner having no bearing on the proper understanding of the invention.

The arrangement just described operates~as follows.

The sheet counting disc is moved toward the stack of sheets for the bearing surface 21 thereof to underlie the stack of sheets. While being rotated in a direction indicated in Figure 6 by an arrow, it contacts by the upper surface of the gas distributor with a stationary gas distributor cover 17'.

This cover 17' (not shown in Figure 6) has three holes: two feeding holes 25' and 24' and one discharge hole 22', to which latter hole 22' the pick-up is connected so as to function as a registration hole. The first two holes 25' and 24' to which a positive pressure is applied are arranged radially in such a manner as to ensure that compressed gas is supplied to the through hole 25 of the gas distributor and to the annular recess 24, the third hole 22' being disposed radially in proximity to the second hole 24' to serve for connecting the pick-up registering pressure variations in the annular recess 24 (pneumatic chamber) during the passage of a separated sheet through the sheet counting disc. When the hole 25 is in registration with the first hole 25' of the gas distributor, a jet of compressed gas is supplied under a sheet 30 being separated lengthwise of the bearing surface, 21 via the passage 26 and the nozzle 28, whereby due to an aerodynamic effect the sheet 30 is properly oriented relative to the bearing surface 21 (Figure 7). A further rotation of the disc results in that its sheet separating tooth 20 enters a space or gap formed between the sheet 30 and the rest of sheets in the stack 31 of sheets to be counted to therefore turn or displace the separated sheet to the otherface of the disc member.While passing through the sheet counting disc, the sheet passes through the space or gap 29 formed between the outer surface of the tooth 20 and the cover 18 to be suspended as if on an air cushion due to the same aerodynamic effect under the action of a jet of gas escaping from the opening 22 in the sheet separating tooth. At the same time, a pressure differential is produced in the annular recess 24 functioning as a pneumatic chamber which signals about such a passage of the separated sheet for the signal to be received and registered by the counter (Figure 8).

The cover 18 attached to the disc member serves to provide a free passage of a separated sheet 30 by the sheet separating tooth 20 and prevents the thus separated sheet from the action exerted by resilient forces of the already separated and counted sheets 32 during such passage, as well as to ensure the constant space or gap 29, which in turn provides for a stable escape of the gas through the registration hole 22.

In this embodiment of the invention, the mechanisms for providing relative movements of the stack of sheets and the disc member are well known and not illustrated in the drawings for the sake of clarity.

For improving the efficiency of the counting device, the sheet counting disc may be of a multiple configuration, that is it may have several shaped recesses, each of the recesses being provided with a corresponding nozzle.

For improved reliability, the sheet counting disc may periodically engage a jet of compressed gas for making a successive sheet being separated from the stack of sheets to conform to the concave surface of the disc member, this jet flowing in a direction from the upper corner of the sheet being separated.

Advantages of this device for counting sheets reside in minimized folding or deformation to which the sheets being counted are subjected, low consumption of compressed gas due to the cyclic engagement thereof, low wear of the bearing surface of the disc member assured by the continuous presence of an "air cushion", and the possibility of its application for counting special types of sheet paper, such as a gummed paper.

With reference to Figures 9 and 10, there is shown another device having a disc-shaped sheet separating assembly, comprising a disc member 33, a nozzle 35 with a pneumatic chamber 36, an ejector 37 and a pressure sensor 38. The disc member 33 has the form of a truncated cone with a shaped recess 39 which defines a sheet separating tooth 40.

The base portion of the disc member has a bearing surface 41 concave in cross-section, the concavity spirally increasing toward the sheet separating tooth 40, the peripheral portion of the concavity adjoining the sheet separating tooth having a slot 42 through which the bearing surface of the disc communicates with the tapered surface thereof. The base of the disc member also has a recessed portion 43 to accommodate thereabove the stationary nozzle 35. The nozzle 35 and the pneumatic chamber 36 are secured by a clamp 44 above the base of the disc member 33 in the recess 43 and are communicable with a source of compressed gas via an ejector 37 by way of conduits 45, the pressure sensor 38 being positioned between the pneumatic chamber 36 and a mixing chamber of the ejector 37.

This device operates as follows.

The disc member 33 is rotated closkwise about its axis. Compressed gas is supplied from the diffuser of the ejector 37 to the nozzle 35 along a pipe 46 and the conduits 45, the compressed gas escaping through an opening 47 toward the periphery of the disc member. The pneumatic chamber 36 disposed on the nozzle 35 communicates with the mixing chamber of the ejector 37 by way of the conduit 45 and through a pipe 48, an underpressure being produced in this chamber 36 when a successive sheet of the stack of sheets blocks a hole 49. The stack of sheets to be counted is moved toward the disc member and set in counting position in such a manner that a peak 50 of the sheets is above the nozzle 35 and the chamber 36 to overlap the hole 49.

During rotation of the disc member 33 a jet of gas excaping from the opening 47 of the nozzle 35 enters a space between the disc member 33 and a sheet 51 being separated from the stack of sheets. When the bearing surface 41 of the disc member 33 assumes a position substantially opposite the opening 47 of the nozzle 35, the sheet is caused to oscillate under the action of the flow of escaping gas to curve and conform to the shape of the bearing surface 41 (Figure 10) dueto an aerodynamic effect.

Oscillations or vibrations of the sheet continue as the concavity of the bearing surface increases to provide for a more reliable separation of the sheet from the stack of sheets because such oscillations cause the sheet to be separated from a subsequent sheet of the stack of sheets despite cohesive forces tending to stick the sheets together or the edges of the sheets to adhere one to another caused by stack cutting. However, vibration of the sheet at the point where the sheet separating tooth enters a space formed between the sheet being separated and a subsequent sheet of the stack affects the reliability of sheet separation. Due to the unstable state of the sheet relative to the bearing surface of the disc member, its edge may collide with the tip of the sheet separating tooth resulting in damage of the sheet, especially in the case of soft paper sheets.

Sheet vibration is caused by attractive force arising in the underpressure zone over the bearing member of the disc member and also by a repulsive force caused by the pressure of the jet of gas exerted on the sheet. This vibration, however, may be effectively controlled. Taking into account that the underpressure produced over the bearing surface of the disc member is directly proportional to the speed with which the gas passes therealong, in order to assure proper orientation of the sheet, it is sufficient to reduce the action of the jet pressure force before the sheet separating tooth while increasing underpressure over the bearing surface of the disc member.This is attained by providing the slot 42 on the periphery of the bearing surface of the disc adjacent the sheet separating tooth so that the bearing surface 41 of the disc communicates with the tapered surface thereof, the slot 42 being therefore intended to maintain a maximum speed of gas flowing along the bearing surface of the disc and minimize the wedging action of the flow of gas. In view of the foregoing, a space is formed between the sheet 51 being separated and the rest of sheets in the stack of sheets into which the sheet separating tooth 40 enters if the disc is further rotated.The sheet 51 entrapped by the sheet separating tooth 40 is displaced to the other side of the disc member through the shaped recess 39, the corner of the sheet being removed from the hole 49 of the pneumatic chamber 36, whereby a pressure differential is produced in this chamber registerrd by the pressure sensor 38. After the sheet has been moved or placed on the opposite side of the disc, a successive sheet of the stack of sheets overlaps or blocks the hole 49 of the pneumatic chamber 36 to result in that an underpressure is produced therein. The jet of gas escaping from the nozzle into the space between the disc and the sheet being separated prevents friction of the sheet against the disc. The clamp 44 provides for arranging the nozzle 35 with the pneumatic chamber 36 in a predetermined position relative to the disc 33.

Increased efficiency of sheet counting may be attained by providing a disc of multiple construction, as described with reference to the previously described embodiment.

Improved reliability of the device for counting sheets in a stack of sheets is ensured by the use of the following elements: an ejector providing for operation of the device from a source of compressed gas, a stationary nozzle providing for continuous passage of gas between a sheet being separated and a disc member, and a through slot arranged in the periphery of the bearing surface of the disc in close proximity to the sheet separating tooth so that the bearing surface of the disc communicates with the tapered surface thereof for proper orientation of the sheet at the moment it is separated from the stack of sheets.

Among advantages of this device are: reliable operation, structural simplicity, lack of friction between the sheet being separated and the disc, prevention of possible damage which can be done to the sheet by the sheet separating tooth during sheet separation, negligeable deformation of the sheet in the course of displacing the sheet to the other side of the disc, and possible use of the device for counting special types of paper.

A mechanism for moving the stack of sheets relative to the sheet separating assembly may be of any known suitable construction, for example, such as that described hereinabove. The pick-up and counter means have not been described for reasons of clarity, since they have no relevance to the essence of the present invention.

In all the devices described herein before, the sheets being counted are moved or turned only in one direction relative to the sheet separating assembly. However, in order to recount the number of sheets in a stack of sheets, a provision may be made for counting the sheets starting from the two opposite sides of the stack of sheets without moving the stack relative to the sheet separating assembly, in other words, to use a reversible sheet separating assembly.

Such a reversible sheet separating assembly is illustrated in Figures 11, 12, 13 and 14 and constitutes yet another embodiment of the sheet counting device according to the invention.

With reference to Figure 11 the reversible sheet separating assembly comprises a disc member 52 having collars 53 and 54 and distributors 55 and 56.

The disc member comprises a flat plate having a radial slot 57. The gas distributors 55 and 56 are provided at their base portions with radial passages 58 and 59 and also have through holes 60 and 61 so that the passages communicate with the opposite sides of the distributor. The distributors 55 and 56 are attached to the opposite sides of the flat disc in such a manner that slotted nozzles 62 and 63 are formed between the disc 52 and the distributors 55 and 56. The collars 53 and 54 are round in crosssection and have the form of arcs bent toward the centre of the disc 52 and attached thereto so as to extend from one side of the disc toward the other side thereof, the end portions of the collars intersecting if viewed axially of the disc. The nozzles 62 and 63 are disposed adjacent the slot 57 to face the collars 53 and 54 raised above the faces of the disc 52.

The aforedescribed reversible sheet separating assembly operates as follows.

The sheet separating assembly is moved toward the corner of the stack of sheets under the stack such that a diagonal line of the stack would pass through the centre of the disc and the sheets would take a position over the disc 52 (Figure 13). During rotation of the disc counterclockwise the hole 60 of the distributor 55 is set in registration with a hole of a stationary plate element (not shown) disposed on a line extending the diagonal line of the sheet and communicating with a source of compressed gas, whereby a jet of compressed gas escapes from the nozzle 62 parallel with the surface of the disc 52 and directed toward and under the sheet 64.Due to the flow of gas in the space between the surface of the disc 52 and the sheet 64 an underpressure occurs resulting in an aerodynamic effect causing the sheet to curve, a thin layer of cushion of gas being formed between the surface of the disc and the sheet.

Further rotation of the disc forms a spice 65 between the sheet 64 being separated and the rest of the sheets in the stack 66 where into the tip of the collar 54 enters to carry the sheet over to the opposite side of the disc.

When counting the sheets in a downward direction, the sheet separating assembly is moved toward the stack of sheets from above, while compressed gas is supplied from the source of compressed gas to the nozzle 63 through the hole 61 of the distributor 56 and the disc is rotated clockwise. The sheets are separated and carried over to the opposite side of the disc essentially as during counting in the upward direction, although this time by means of the collar 53.A major advantage of the reversible sheet separating assembly resides in that, apart from saving time, it enables the reliability of repeated or check counting to be substantially improved, since the sheets are counted from the other side of the stack whereby a possible error (due to separation of two or more sheets stuck together) caused by a defect in one side of the stack corner, usually repeatable if the sheets are recounted from the same side, is minimized. Structural simplicity, lack of wear and clogging due to the use of compressed gas for sheet separation, as well as operational versatility of the sheet counting device make the device reliable in operation and expand the range of its application.

The mechanism for moving the stack of sheets to the sheet separating assembly or for moving the sheet separating assembly toward the'stack of sheets, as well as the means for registering and counting sheets separated from the stack of sheets, have not been described in detail becuse they may be embodied in any suitable manner in the art.

Claims (10)

1. A device for counting sheets in a stack of sheets, comprising a pneumatically operated sheet separating assembly insertable between the sheets for separating each successive sheet from the stack of sheets, the sheet separating assembly having a bearing surface for accommodating a sheet, means for carrying the sheet in a sheet registering position over the bearing surface, and a register connected to a sheet counter for counting the separated sheets, the sheet separating assembly and the stack of sheets being capable of relative displacement for separating successive sheets from the stack of sheets, the sheet separating assembly being provided with a slotted nozzle communicable with a source of compressed gas to produce a flat jet of gas directed lengthwise of the bearing surface, the pressure and the flow rate of gas in the jet of gas being selected so as to produce an underpressure in the proximity of the bearing surface to cause the sheet being separated from the stack of sheets to adjoin the bearing surface with a gap between the sheet and the bearing surface.

2. A device as claimed in claim 1, wherein the bearing surface is a flat stationary plate insertable between the sheets at an angle thereto, there being provided an endless conveyor serving to carry the separated sheet over the plate.

3. A device as claimed in claim 1, wherein the sheet separating assembly is a disc member arranged for rotation in the plane of the sheets and having radial slots passing arcwise of the disc member for carrying the sheets over from one surface of the disc member to the opposite surface, a slotted nozzle extending in a radial direction being arranged adjacent each sheet separating tooth, the slotted nozzle being formed in the body of the disc member on the side of its bearing surface, all the nozzles being communicable with the source of compressed gas tbrough a gas distributor acting to alternately connect the nozzles with the source of compressed gas.

4. A device as claimed in claim 3, wherein the disc member is provided with a recessed portion, the nozzle being arranged in a stationary position relative to the disc in the recess, which position is adjustable.

5. A device as claimed in claim 3, wherein the bearing surface of the disc member is provided with a radially extending concave portion between the nozzle and the sheet separating tooth.

6. A device as claimed in claim 5, wherein the peripheral portion of the bearing surface of the disc member adjacent the sheet separating tooth is provided with a through opening in the form of a slot connecting and bearing surface of the disc member with a tapered surface thereof.

7. A device as claimed in claim 1, having a sheet separating assembly in the form of a flat disc wherein the outer peripheral edge of the disc accommodates two collars in the form of arced sectors interconnected at their one ends and having the other ends thereof extending in the zone of the shaped recess to the opposite bearing surfaces of the flat disc.

8. A device as claimed in any one of claims 1 to 6, wherein the register is defined by an annular chamber arranged in the body of the disc, the chamber being communicable by a passage with the source of compressed gas for the nozzle, and by an opening with a sheet counting position surface with a pneumatic pick-up communicable with this chamber.

9. A device as claimed in any one of the preceding claims, wherein an inlet of the nozzle communicates with the source of compressed gas through an ejector, the upper portion of the nozzle having a chamber with a hole overlappable by the sheet during sheet counting, the chamber communicating with the mixing chamber of the ejector by a conduit provided wth a pressure sensor.

10. A device for counting sheets in a stack of sheets, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.