This invention concerns a tape feed arrangement suitable for feeding lengths of tape such as of paper to some other process or operation. In particular, this invention relates to improvements in or relating to a known kind of tape feeder, such as a so-called "tabber" as defined hereinafter. This invention further relates to an improved form of tabber.

In various manufacturing or other industrial processes, it is necessary to supply pieces of tape each cut to a predetermined length, the tape being drawn from a roll thereof. For example, in a counting operation performed on sheets of paper in a stack, it may be desirable to insert a plurality of paper tape tabs between sheets of the stack as the counting progresses, to mark each count of some predetermined number of sheets. This is conveniently performed by apparatus which draws marker tape from a roll and which inserts a length of drawn tape to lie between the required two sheets as the counting progresses, the apparatus simultaneously cutting off the inserted tape to the required length.

One known form of such apparatus comprises feed means to draw paper tape from a roll thereof, a tape guide chute extending from the feed means to a point adjacent the location at which a tab is to be inserted between two sheets in a stack, and a guillotine mounted on the end of the chute remote from the feed means to cut an inserted tab from tape in the guide chute. Such apparatus is hereinafter referred to as a "tabber of the kind described" .

The tape used with a tabber of the kind described generally is a smooth paper tape, provided in roll form. The feed means draws tape from the roll and drives it along the guide chute to the guillotine

disposed at the remote end of that chute; when a tab is to be inserted, the feed means is operated for a predetermined period to project a required length of tape beyond the guillotine, whereafter the feed means is stopped and the guillotine is operated and then returned to its initial position, ready for the insertion of a further tab.

It sometimes happens that the cut edge of a piece of tape lying within the guide chute of a tabber of the kind described can become blocked for some reason. If this happens and the tape feed means is operated to insert another tab, tape is pushed into the guide chute notwithstanding the blockage at the remote end of the chute; this causes the tape to crumple within the chute and perfect the tape jam which must then be cleared before the tabber may be operated once more. It is an object of the present invention to provide a tape feed arrangement suitable for use in a tabber of the kind described, where no, or only minimal, driving of the tape takes place in the event that tape cannot be projected from the remote end of the chute.

According to the present invention, there is provided a tape feed arrangement comprising: means for supporting a roll of tape; drive means for drawing a succession of predetermined lengths of tape from the roll; a tape motion detector mounted between a supported roll of tape and the drive means, which detector includes a freely-rotatable roller around part of the periphery of which the tape is constrained to pass; and means to detect rotation of the roller on actuation of the drive means and to inhibit further operation of the drive means should no roller rotation be detected.

The tape motion detector may include a flange having a plurality of notches formed therein, the rotation detecting means being arranged to sense the

notches in the flange passing through a detection station on rotation of the roller. For example, an infra-red slot switch may be disposed over the flange periphery to sense the passage of the notches therethrough.

In a preferred arrangement, the rotation detection means determines the length of tape advanced on each cycle of operation from the angle of rotation of the roller, by counting the notches of the flange passing through the detection station. The determined length may then be compared with a required tape feed length, and an error condition being signalled should the determined length fed differ by more than some pre¬ determined amount from the required length. The arrangement may be enhanced to operate on a closed-loop basis, with the drive means being actuated dependent upon the length of tape determined as having been fed, whereby the drive means will feed a uniform length of tape on each cycle of operation. To allow precise control it is advantageous to employ an induction motor in the tape drive means, though other forms of electric motor could be used, such as a stepper motor. The output shaft of the motor may define combination with a pinch roller a drive nip through which the tape passes.

This invention extends to a tabber for inserting between two sheets of a stack thereof a tab cut from a length of tape, which tabber comprises a tape feed arrangement of this invention as described above in combination with a tape guide chute extending from the tape drive means to a point adjacent the location at which a tab is to be inserted between two sheets in a stack, and a guillotine mounted on to the end of the chute remote from the feed means to cut an inserted tab from tape in the chute.

By way of example only, one specific embodiment of

a tabber of the kind described, but constructed and arranged in accordance with the present invention, will now be described in detail, reference being made as appropriate to the accompanying drawings, in which:- Figure 1 is a diagrammatic view of the embodiment of tabber;

Figure 2 is a diagrammatic sketch showing the tape drive mechanism and tape movement detector used in the tabber of Figure 1; and Figure 3 is a block diagram of a control arrangement for use with the drive mechanism of Figure 2.

Referring initially to Figure 1, there is illustrated diagrammatically a tabber constructed and arranged in accordance with the present invention, and suitable for use in conjunction with apparatus intended to count the number of sheets in a stack, the tabber inserting a paper tab between two sheets each time the count reaches a predetermined value - for example, after each 100 counted sheets. The tabber has a reel 10 mounted on a support bar 11 and arranged to carry a roll of paper tape from which the tabs are to be cut, the bar 11 being adjustable to allow variable positioning of the tabber. A motor-driven tape feed mechanism 12 draws tape from a carried roll, and feeds the tape to tape guide chute 13, for supply to a guillotine indicated generally at 14, disposed at the end of the chute 13 remote from the feed mechanism 12. The guillotine 14 is operated by a flexible Bowden- cable 15 connected back to an actuator (not shown) within the feed mechanism 12. The guide chute 13 may be relatively long (and perhaps up to 750 mm, or even more) and curved, in order to allow the accommodation of the support arrangement 10 and feed mechanism 12 at a position remote from the stack of sheets being counted, with the guillotine 14 being disposed closely

adjacent that stack to permit the insertion of tabs at appropriate points therein, as the count proceeds.

Referring now to Figure 2, there is shown in diagrammatic form the feed mechanism 12 of the tabber of Figure 1. Tape 20 initially passes between a pair of fixed guide pins 21 and 22 supported on a frame (not shown) of the feed mechanism, the pins being disposed so that the tape may enter the mechanism from any position over a wide angular range, to allow accommodation of the paper tape reel at a position to suit a particular installation. From the pins 21 and 22, the tape passes over the periphery of a detector roller 23, and then through a drive nip 24, from where the tape is fed into the chute 13. The detector roller 23 is freely rotatably mounted on the mechanism frame, and carries a flange 25 having four notches 26 formed in its periphery. The flange 25 passes through a photoelectric slot switch 27 which produces an output every time a notch 26 passes therethrough, the switch being connected to a controller (not shown) for the tabber, as a whole.

The nip 24 is defined by the output shaft 30 of a electric motor 31 (such as an induction motor) and a pinch wheel 32 carried in a stirrup 33 and urged by spring 34 into engagement with the shaft 30. The pinch wheel is conveniently defined by a ball bearing assembly. The stirrup 33 is formed integrally with a spindle 36 arranged for sliding movement within a bush 37 adjustable with respect to a base-plate 38, to allow the spring force to be varied.

The force exerted by the spring 34 is selected having due regard to the physical properties of the tape 20, such that should movement of the tape be blocked downstream of the nip 24, slippage should occur between the motor shaft 30 and the tape 20, upon operation of the motor 31. If the motor is driven but

no movement of the tape occurs, the detector roller 23 will not turn so that the switch 27 provides no output; upon detection of this condition, further operation of the motor 31 may be inhibited until the tape blockage has been corrected. Equally, should the roll of tape run out, no output will be obtained from the switch 27 and again further operation of the motor 31 may be inhibited. Simultaneously, a suitable alarm may be issued to warn an operator that attention is required. Figure 3 shows a controller for use with the tape feed arrangement described above. The output from the slot switch 27 is fed to circuit 40, which also provides the drive current for motor 31. A variable control 41 allows the setting of the required length of tape to be fed by the drive nip on each cycle of operation, triggered by a signal on line 42. The motor 31 is normally driven at a pre-set rate, and so the control 41 conveniently varies the time for which the drive current is supplied to the motor. An audible alarm 43 may also be energised by the circuit 40, should an error condition occur.

It will be appreciated that the circuit 40 may detect non-rotation of the roller 23, since the signal from the slot-switch 27 will then be constant. If therefore drive current is supplied to the motor 31 and no rotation of the roller is detected, a warning of an error can be given, and further operation of the motor can be inhibited until the reason for the error is corrected and the controller is reset. In addition to detecting the rotation of the roller 23, the controller may be arranged to detect the length of tape fed by the drive nip in each cycle of operation. This may be achieved by counting the number of pulses detected by the circuit on each tape-feeding operation, which bears a direct relation to the tape length drawn over the roller 23. Resolution of the

detection may be enhanced by increasing the number of notches 26 in the flange 25, and also increasing the diameter of the flange.

Should the length detected as having been fed differ by more than a permissible amount from the pre¬ set feed length, an error condition can be signalled by the controller. Alternatively, the operation of the motor may be controlled dependent upon the detected length fed as compared to the pre-set feed length, thus giving closed-loop operation resulting in accurate feeding of the required length of tape on each operation cycle.