US 3770264 A
A paper stacker for stacking a continuous paper web in fan-fold form from a printer is disclosed. Rollers having radially projecting resilient fingers engage both folded edges of the web as it is stacked. The rollers are each driven by a motor through a gear secured to the roller shaft. The motor is carried on a plate pivotted about the shaft the plate being held against rotation about the shaft by a spring. When the stack height brings the upper surface of the stack sufficiently close to the rollers the load on the rollers is sufficiently great to cause rotation of the plate against the tension of the spring, thereby making an electrical contact to actuate mechanism for raising the rollers.
Description (OCR text may contain errors)
United States Patent 1 1 Sturman et al. I 1 Nov. 6, 1973  POSITION SENSING APPARATUS 3,083,010 3/l963 Salmon et al. 270/73 l,lO9,296 91914 L 's [751 Inventors: Geoffrey Wilfred 3,640,521 2/1972 HZYIL 270/61 F Frederick Sinfield, both of Letchworth, g Primary Examiner-Robert w. Michell  Assignee: International Computers Limited, Assistant 'f T Helm London, England Attorney-Kath Misegades and George R. Douglas, Jr. 221 Filed Dec. 10, 1970  ABSTRACT [21 Appl. No.: 96,798 A paper stacker for stacking a continuous paper web in fan-fold form from a printer is disclosed. Rollers having radially projecting resilient fingers engage both folded  Forelgn Applicaumi P nomy Data edges of the web as it is stacked. The rollers are each Dec. 16, 1969 Great Br1ta1n 6l,l53/69 driven by a motor through a gear Secured to the roller shaft. The motor is carried on a plate pivotted about  [1.8. CI 270/79, 73/432 R, 340/280 the Shaft the plate being held against rotation about the  'llil. Cl 365]] 45/20 Shaft by a spring w the stack height brings the  Fleld of Search 270/79, 61-62, upper Surface of the Stack sufficiently close to the 270/82 73; 340/259; 271/8, 63; ers'the load on the rollers is sufficiently great to cause 83/83 rotation of the plate against the tension of the spring, 0 thereby making an electricalrcontact to actuate mecha-  References and nism for raising the rollers.
UNITED STATES PATENTS 4 Claims, 2 Drawlng Figures 3,5l0,899 5/1970 Vollenweider et al 15/DIG. 2 3,178,172 4/1965 Lettan 270/79 POSITION SENSING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to position sensing apparatus and particularly, but not exclusively, to apparatus for sensing the position of one surface of a stack formed, for example, by stacking apparatus.
SUMMARY OF THE INVENTION According to one aspect of the invention a position sensing device for detecting the position of a moveable surface included at least one member positioned on a rotatable shaft, the shaft being positioned transversely to and spaced away from the surface in the direction of movement of the surface; drive means supported on a mounting rotatable about the shaft for applying rotational drive to the shaft in one sense; means for applying a predetermined force to resist rotary movement of the mounting about the shaft in the opposite sense and means for detecting rotary movement of the mounting about the shaft in said opposite sense against the applied force, whereby movement of the surface towards the shaft causes frictional engagement of said member with the surface at a predetermined spacing between the surface and the shaft sufficient to overcome said force and produce said rotary movement of the mounting.
According to another aspect of the invention stacking apparatus for stacking a continuous web in fan-fold form includes a support surface for a fan-fold stack; a support member carrying a position sensing device; means operable in response to detection of the rotary movement of the mounting to produce relative. motion between the support member and the support surface to increase the spacing therebetween and thereby maintain the support member at a substantially constant spacing from the' face of the stack.
BRIEF DESCRIPTION'OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a stacking apparatus is arranged to form a pre-folded paper web 1 into a compact stack 2. The stacking arrangement shown in the Figure is particularly suitable for handling a continuous paper web from, for example, the printing mechanism ofa data processing equipment. Typically, such equip ment uses continuous stationery derived from a stack in which the web is folded back and forth in a zig-zag configuration and it is required to reform the web into a similar stack after it has been printed.
The stacking apparatus is supported on a hollow base 3, the top 4 of the base 3 forming a stacking platform. A vertical arm 5 is provided at each side of the base 3.
The arms are spaced apart at their upper ends by a pair" of rods 13. A framework 6 is mounted between a pair of sliders 7, each slider being arranged to move vertically along one of the arms 5. An endless chain 38'is carried over sprockets 39 and 40, respectively mounted at the upper and lower ends of each of the arms 5, and
the sliders 7 are secured to the chains 38 by means of connecting pieces 41. The upper sprockets 39 are idlers and are each supported on a stud 42 in the arms 5. The lower sprockets 40 are mounted on a shaft 42 passing cross the interior of the base 3. The shaft 43 is coupled in a conventional manner by gearing (not shown) through an electrically-actuated clutch (not shown) to a drive motor (not shown) within the base 3. It will'be realised, therefore that by the selective operation of the clutch theshaft 43 may be driven to move the chain 38 and raise the entire framework 6. It will also be appreciated that reversal of the direction of rotation of the motor within the base 3 will cause the entire framework 6 to be lowered if the clutch is energised.
The framework 6 consists of a pair of side members 8 secured together by bars 9 passing across the width of the framework 6. A pair of plates 10 are supported by the side members 8 between the arms 5. The end plates 10 house bearings (not shown) for transverse shafts 11 which carry feed rollers 12.
The shafts 11 are driven ,by conventional gearing (not shown) from a splined shaft 44 arranged vertically in bearings of which only one, 46, is shown, carried by one of the arms 5. The splined shaft 44 is driven by bevel gearing 45 through a further clutch and motor combination (not shown) within the hollow base 3.
At the left-hand end, as shown in FIG], the framework 6 supports a shaft 14. The shaft 14 passes across the framework and is journalled into the side members 8. Finger-rolls 15 are spaced apart along the shaft 14. Parallel with the shaft 14 a bar 49 is also supported between the side members 8, and the bar 49 carries a number of stop members 50 and flexible strips 51, the members 50 and strips 51 being spaced apart along the bar- 49 to lie between the finger rolls 15. FIG. 2 shows the arrangement of the finger rolls 15, the members 50 and the strips 51 in greater detail.
As indicated in FIG. 2,- each finger roll consists of a hub 16 secured to the shaft'l4. The hub 16 is of resilient material and has a number of equally-spaced fingers l7 projecting outwards from it. The fingers I7 taper from the hub towards their free ends. The bar 49 is positioned so that it is clear to the fingers 17 of the rolls [5. Intermediate adjacent rolls l5 stop members 50 are secured to the bar 49, each stop member having a downwardly projecting portion to act as a stack-edge alignment member, and an upper end bentinward's to form an anchoring point to which is secured one end of a flexible strip 51'. The strip 51, which is preferably made of spring steel, is curved first upwards, then downwards to enclose the shaft 14, the free end of the strip 51 being passed through a hole 52 provided for the purpose in the stop member 50. The free end of the strip 51 is bent sharply-downwards to contact the out- .ward'face of the member 50, being located in this position by the tension induced into the strip SI by its curvature.
The side members 8 (FIG. 1) have channels 18 formed'in their outward faces towards those ends of the members 8 remote from the shaft 14. Extension pieces pieces 19 are held in position in the channels 18 by means of a thumbscrew clamp 21 which project through slots in the respective side members 8 so that the extent of the projection of the pieces 19 from the ends of the side members 8 may be adjusted.
The right-hand ends, as shown in FIG. 1, of the extension pieces 19, carry a finger-roll and stop member arrangement similar to that described above at the lefthand side of the framework 6. A shaft 22, journalled into the extension pieces 19 carries finger rolls 23. A bar 53 carries right-hand stop members 54 and flexible strips 55 carried by the members 54 passes round the shaft22.
The finger roll shafts l4 and 22 are each associated with an independent drive unit 24. The drive units 24 are similar, that associated with the shaft 22 being shown with greater clarity in the figure and being described in detail. This drive unit 24 includes a plate 25 which is pivoted on the shaft 22. A shaft driving gear 26 is secured to the shaft 22 so that the plate 25 is sandwiched between the gear 26 and the outer face of one of the extension pieces 19. The plate 25 carries a stud 27 on which is mounted an idler gear 28 meshing with the driving gear 26. A motor 29 having a drive shaft 30 is carried on the plate 25 and a gear wheel 31 meshing with the idler gear 28 is provided on the motor shaft. Thus, the idler gear 28 merely serves to couple the drive from the motor 29 to the driving gear 26, and so to the shaft 22, the motor being connected so that, when engaged, it drives the gear 26 in an anticlockwise direction as shown in the drawing.
A support block 47 is secured to the extension piece 19 adjacent the drive unit 24 and carries at one end a thumbscrew 32. The end of the thumbscrew 32 projects from the block 47 towards the plate 25 and a tension spring 33 is used to couple the screw 32 to the plate 25 to resist rotation of the plate 25 in a clockwise direction as shown in the drawing. The plate 25 also has a lug 34 turned at right angles to the plane of the plate 25. An adjusting screw 35 is threaded through the lug 34 and the end of the screw 35 projects beyond the plate 25 in such a direction as to lead that edge of the plate 25 if the plate rotates about the shaft in a clockwise direction as shown on the drawing. A microswitch 36 is supported on a mounting block 48 so that it has an actuating lever 37 resting against the projecting end of the screw 35.
An electrical circuit, (not shown) is provided to control the operation of the motors of the apparatus and this circuit has the following features: The motor (not shown) which drives the chain 38 is controlled by a switch which is normally closed when the apparatus is in use, so that energisation of the clutch (not shown) referred to in connection with the chain-drive transmits the motor drive to the chain 38. This drive motor is normally running in such a direction as to move the chain 38 to raise the framework 6. In addition, further switches are provided to reverse the direction of the motor drive and to energise the clutch under manual control, so that the framework 6 may be moved upwards or downwards under manual control in order that it may be positioned at a required height. The microswitch 36 is connected into the energisation circuit of the clutch so that the clutch is energised whenever the microswitch 36 is operated. Because the normal direction of the motor drive is such that the framework 6 is raised, it will be seen that operation of the microswitch 36 under these normal operating conditions causes the framework 6 to rise for as long as the microswitch remains operated. The switch referred to above initially energising the chain drive motor is also used to energise the motor (not shown) associated with the drive to the splined shaft 44, so that under normal operational conditions the feed rollers 12 are continuously rotating.
In operation, the end of a paper web 1 to be stacked is passed downwards between the rods 13 and then through the feed rolls 12. The rolls 12 are arranged lightly to grip the web and the direction of rotation of the rolls 12 is such as to feed the web downwards. The rolls 12 preferably each have a resilient periphery and are arranged to skid on the surface of the web 1 so that the web 1 is not damaged by the rolls 12 in the event that the external supply of the web 1 is at a rate less than the stacker can handle. A refinement of operation that may be employed is to arrange the circuit to control the drive to the splined shaft 44 in such a way that the shaft 44 is driven only while the web 1 is being supplied .to the stacker.
The web-end passed downward through the feed rolls 12 is laid on the upper surface 4 of the base 3 so that the preformed folds in the web 1 enable the incoming web to take up its originally folded form. The framework 6 is then lowered by manual operation until the tips of the fingers 17, of the finger rolls,15 and 23 gently stroke the folds of the stack 2 as it is formed, the position of the extension pieces 19 being adjusted with respect to the framework 6 so that the fingers of the rolls l5 and 23 act on the stack near its folded edges.
As the web 1 is fed into the stacks the pre-foldcd creases allow it to assume the original zig-zag formation with the result that the pre-formed creases are impelled towards one or other of the stop members 50 or 54 alternately. As a crease approaches the appropriate stop member, it contacts the curved inward-facing surface of the associated flexible strip 51 or 55 respectively. The action of the strip 51 or 54 is to absorb the kinetic energy of the approaching crease and the stop member 50 or .54 then acts as an aligning stop to dress the incoming web 1 into the stack 2. The finger rolls 15 and 23 aid the formation of the stack by lightly dressing the incoming web downwards and towards the respective stop members 50 and 54. At this point in the operation, the circuitry associated with control of the height of the framework 6 is put into normal operation.
As the web 1 continues to feed into the stack 2, the stack gradually increases in height. As the stack 2 grows higher, the resilient fingers of the rolls l5 and 23 are flexed more and more, with the result that a progressive increase in resistance to the rotation of the rolls 15 and 23 is built up. For the sake of clarity the operation of the drive unit 24 associated with the finger rolls 23 will be considered in detail.
It will be recalled that the finger rolls 23 are driven by the motor 29 through gears 31, 28 and 26 and that the gear 26 rotates in an anticlockwise direction as shown. It will also be remembered that the plate 25 is pivoted about the finger roll shaft 22 but is maintained against turning in a clockwise direction by the force exerted by the spring 33. Hence, as the resistance to rotation of the finger rolls 23, and, in consequence to rotation of the gear 26, is built up the torque applied to turn the gear 26 results in the gear 28 moving in a clockwise direction round the periphery of the gear 26, thus pivoting the plate 25 clockwise about the shaft 22 against the force exerted by the spring 33. This movement of the plate 25 carries the screw 35 towards the microswitch 36, flexing the levers 37, until the microswitch 36 is actuated. It will be recalled that actuation of the microswitch 36 causes the framework 6 to be raised, and this upward movement of the framework 6 opens the gap between the top surface of the stack 2 and the finger rolls 23 so that resistance to rotation of the rolls 2-3 is lessened. The plate 25 now restores under the influence of the spring 33, and the screw 35 moves away from microswitch 36, which is thus allowed to restore to its initial state. It will be seen, therefore, that the right-hand drive unit 24, allows the framework 6 to be raised to follow the increasing height of the right hand edge of the stack 2, as shown. The left hand drive unit 24 operates in the same way with respect to the lefthand edge of the stack 2.
It will be realised that the provision of two drive units 25 permits the finger rolls and 23 at opposite edges of the stack to act together to align the edges of the stack by causing successive layers to be located on the stack according to the pre-formed folds. It will be understood, however, that in the arrangement so far described, where the entire framework 6 is rigidly mounted on the slides 7, it is only necessary to sense the height of the stack by means of one drive unit 24, so that under these conditions satisfactory stacking may be obtained by providing a moveable plate and a microswitch 36 in only one of the driving units 24.
It has been found, however, that, particularly for high feeding rates of the web 1, the provision of microswitches 36 in both drive units 24 allows greater operational tolerance in the mechanical response of the units 24, In particular, the tolerance of the apparatus to the mechanical restoration characteristics of the plates 25 is improved. It is also found that under some conditions of operation it is desirable to arrange that the microswitches 36 are mounted on the opposite sides of the plates 25 to that shown in the drawing, the lugs 34 and adjusting screws also being positioned on the opposite sides of the plates 25. In this way the plates 25 tend to move away from instead of towards the microswitches as the stack height increases. Thus a rapid build up of the stack with a consequent violent swing of the plates 25 can take place without risk of damage to the microswitches 36 by impact from the plates 25. It will be realised that with this arrangement the microswitches are actuated by the plates 25 in their normal positions and are de-actuated as the plates 25 are moved in response to increasing stack height, the microswitches being arranged to make an electrical circuit upon de-actuation.
It will also be readily seen that the height of the folded edges of the stack 2 increases at a greater rate than does the height of the centre of the stack 2. It is for this reason, for example, that it is preferred to make the centre of the upper surface 4 of the base 3 higher 7 than those edges of the surface 4 on which the folded edges of the stack 2 rest, as indicated in the drawing. if, instead of rigidly mounting the framework 6, in the slides 7, the framework 6 is pivotally mounted and a height adjusting structure including, for example, a separate chain 38 for each end of the framework 6 is provided, then the use of the position sensing arrangement in the drive units 24 associated with both sets of finger rolls l5 and 23 would allow the height of the ends of the framework 6 to be separately controlled. Under these conditions, the finger rolls 15 and 23 respectively associated with the opposite edges of the stack 2 may each be maintained in an optimum position with respect to the particular associated edge.
It will be seen, therefore, that the drive units 24 in association with the finger rolls 15 or 23 form devices both for sensing the position of the upper surface of the stack 2 with reference to the ends of the framework 6 and for controlling the height of the framework 6 to maintain the spacing between the framework 6 and the upper stack surface within a predetermined tolerance, dependent upon the resilience of the fingers of the finger rolls and the adjustment of the force exerted by the springs, such as 33, and upon the adjustment of the screws 35.
The movement of the plate 25 is primarily controlled by the resistance to rotation offered to the finger roll shaft 22, and it will be realised that rolls each having, for example, a flexible'periphery could be substituted for the finger rolls shown, provided that these rolls are able to engage the upper surface of the stack 2 with sufficient frictional resistance to motion to produce movement of the plate 25 without at the same time damaging the surface of the stack 2.
It is also to be understood that conversely, the use of the finger rolls is not limited to the actuation of the position sensingdevice within the drive unit 24. As has been pointed out, where only one position sensing device is used, a second set of finger rolls is used to aid in forming the stack. Moreover, finger rolls may also be used in opposition to replace th resilient surfaced rolls 12 in feeding the web into the stacking arrangement.
The use of finger rolls in this position may actually aid the formation of the stack by allowing the pre-folded creases in the web to pass through the feeding station without any contact from feeding rolls which would tend to flatten the creases.
It will be recalled that the base 3 is described as housing separate motors to drive the splined shaft 44 and the chain sprocket 40 respectively. It will be understood, however, that a single motor may be used as the prime mover for both purposes, the drive from the motor being communicated by conventional gearing and electrically controlled clutches. For example, a first gear train may be used to drive the splined shaft 44, and a clutch in this drive chain may be interlocked by means of an electrical connection so that the shaft 44 is driven only while the web 1 is being supplied to r the stacking arrangement. If, for example, the stacker is employed at the output of a printing apparatus, an electrical signal may be transmitted to actuate the splined shaft 44 clutch whenever a spacing or paper feeding operation'is initiated by the printing apparatus. The facility for manual control of the lowering of the framework 6 may be provided by having a dual drive,
effective selectively to produce raising or lowering respectively of the framework-6. If each drive is separately clutchable, then a conventional electrical interlock may be used to ensure that while signals from the microswitch or switches 36 are effective, to produce upward movement of the framework, the upward" clutch cannot be actuated while the downward" clutch is being signalled under manual control, and indeed to provide such a manual override for movement of the framework 6 in either direction.
We claim: i
1. Apparatus for stacking a precreased fan-fold web, including a base member; a framework mounted for movement towards and away from the base member;
web feeding means mounted on the framework and operable to feed the web when in an unfolded condition towards the base member such that a stack of refolded web is formed on the base member the stack having opposed edges formed by the precreased folds in the web; a shaft mounted on the framework; a stack edge contacting roll mounted on the shaft, the roll being positioned adjacent to one of said edges so that it comes into contact with the web being fed to assist in the refolding of the web onto the stack as the depth of the stack increases; means operable to rotate the roll; detecting means operable in response to a predetermined increase in the resistance to rotating of the roll consequent upon its contact with the increasing depth of the stack; and driving means operable in response to operation of the detecting means to move the framework away from the base member to allow the edge contacting roll to accomodate to the increasing depth of the stack 2. Apparatus as claimed in claim 1 in which the detecting means includes a plate pivotally mounted on said shaft; spring means resiliently urging the plate towards pivotting in one direction about the shaft; electrical switching means positioned for operation by the plate pivotting in a direction opposite said one direction and in'which the said driving means is mounted on the plate. a
3. Apparatus as claimed in claim 2 in which the roll has a plurality .of radially arranged fingers of resilient material.
4. Apparatus as claimed in claim 1 in which the base member with which the stack is in contact is so shaped as to provide first and second outer portions for contacting and supporting the opposed folded edges of the stack, and a third portion intermediate the first and second portions raised relative to the first and second por-