US2275409A

US2275409A - Adhesive tape dispenser

Info

Publication number: US2275409A
Application number: US261537A
Authority: US
Inventors: Arthur A Anderson
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1939-03-13
Filing date: 1939-03-13
Publication date: 1942-03-10
Anticipated expiration: 1959-03-10

Description

March 10, 1942.

A. A. ANDERSON ADHESIVE TAPE DISPENSER Filed March 15, 1939 4 Sheets-Sheet l March 19, 1942. ANDERSON 2,275409 ADHESIVE TAPE DISPENSER Filed March 15, 1939 4 Sheets-Sheet 2 N max 07 ESQ M36074.

y L ,I

March 10, .1942. D N 2,275,409

ADHES IVE TAPE DISPENSER Filed March 13, 1939 l 4 Sheets-Sheet z I .5206 or:

o'zzzrfafizcleniom WW1 W Z March 10, 1942. A. A. ANDERSON 2,275,409

I ADHESIVE TAPE DISPENSER Filed March 13, 1959 4 Sheets-Sheet 4 wfm Patented Mar. 10, 1942 ADHESIVE TAPE DISPENSER Arthur A. Anderson, St. Paul, Minn., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware Application March 13, 1939, Serial No. 261,537

16 Claims.

This invention relates to an adhesive tape dispenser adapted to receive a roll of non-drying pressure-sensitive adhesive tape and automati cally eject predetermined unit lengths which the operator cuts off with a shear, each operation of the shear causing the next unit length to be automatically advanced for cutting oil. The only effort required of the operator is to push down the handle of the shear blade with the finger tips of one hand and to remove the pieces of tape as they are out off.

A feature of the dispenser is that it can be quickly adjusted to vary the predetermined unit length of tape to be dispensed. Another feature is that when a piece of tape is cut off it is automatically positioned with its inner end portion temporarily adhering to a support or ledge from which it can be readily removed for use, as for example by employing the fingers of the same hand employed in operating the shear. Other features and advantages will be apparent from the description and drawings of an illustrative portable embodiment.

The described embodiment illustrates a form of construction designed especially for use in dispensing a normally tacky and pressure-sensitive adhesive tape having a backing of unified creped paper, exemplified by the adhesive tape of this kind which is sold under the trade-mark Scotch," for example. It will be understood, however, that the invention is notlimited to a device for dispensing any one particular kind of adhesive tape, since the principles involved may be employed wherever expedient; and the illustrated form may be modified, if necessary or desirable, to adapt it to other forms of adhesive tape, including gumrned paper tape. By normally tacky and pressure-sensitive adhesive tape, reference is made to the property of the adhesive coating being stably in a condition such that it does not need to be activated by heat or solvents, or be otherwise prepared, in order to secure good adherence to surfaces against which the adhesive surface is pressed by a light application of manual or mechanical pressure. Modern tapes of this type have a non-offsetting adhesive, the adhesive being more cohesive than adhesive, so that the tape can be unwound from rolls and removed from surfaces to which temporarily applied without adhesive transfer occurring.

In the accompanying drawings:

Fig. 1 is a side elevation view of the side carrying the tape dispensing mechanism proper;

Fig. 2 is a plan view;

Fig. 3 is a front elevation view as the operator faces the dispenser;

Fig. 4 is a side elevation showing the opposite side where the cam shaft and its variable ratio drive are located for regulating the length of the tape to be dispensed;

Fig. 5 is a longitudinal vertical section through the axes of the dispensing rollers and the driving shaft, taken on 5--5 of Fig. 2;

Fig. 6 is a transverse vertical section through the tape dispensing mechanism, taken on 6-6 of Fig. 2; and

Fig. 7 is a simplified circuit diagram, showing the operation of the electric control system.

The dispensing machine proper is located upon the rectangular top IU of a box H, the latter having an open bottom and being screwed to base l2. The switching elements and wiring of the motor control system are located within the box and are not shown, although indicated schematically in the circuit diagram, since the construction thereof is not part of the invention and suitable devices can be readily found on the market. The top of the box thus serves as the base for the mechanical elements of the mechanism, and also for the electric driving motor. Looking toward the front of the machine, the right-hand half of the top base supports the tape dispensing unit, and the left-hand half supports the driving unit, including the motor, the cam shaft and the variable ratio drive.

The dispenser mechanism will be described first. Extending along the front of the top base and secured thereto, there is a rectangular upright supporting plate l3, which is recessed along the front to carry a fixed shear blade M, the upper edge of which is adjacent the upper edge of the supporting plate. A stiff metal strip l5, having the upper part bent forward at right angles to provide a fiat horizontal tape supporting ledge it, rests against the outer face of the shear blade, the ledge being spaceda short distance below and parallel to the edge of the blade. The ledge strip and the blade are jointly secured to the supporting plate by machine screws l1 and I8 Joumaled in the outer end portions of the supporting plate and blade, and in support I9 located at the rear right corner of the top base, is shear shaft 20, which runs back at right angles to the fixed blade. The front end of this shaft projects through the fixed blade and is secured to the end of moveable shear blade 2|, which pivots with the shaft to coact with the fixed shear blade in cutting off tape. The angle be- .for manually pushing down the blade with the fingers of one hand. The blades are preferably of the right-angle edge type, as shown. The

moveable blade and the tape supporting ledge are located such that when the moveable blade has been pushed down past the resisting or cutting edge of the fixed shear blade, it will bear against the top surface of the ledge. The shear shaft is provided with a stop finger 23, which is shaped to bear down against the top base when the moveable shear blade is in normal open position and thus limit the upward travel of said blade, so that the blade angle is in the neighborhood of 45. The moveable blade is triangularly shaped so that the handle will be at only a small angle to the horizontal when the blade is in open rest position, thus making it very convenient to operatewith the fingers.

The shear shaft extends rearwardly of support 19 and is provided with an adjustable collar 24 spaced from said support, and which can be locked in desired position by means of its setscrew, and about the shaft between these there is located a concentric loaded coil spring 25, the ends of which are fastened to the support and collar. The spring is loaded by twisting and compression so as to subject the shear shaft both to torque and to rearward pushing, each of which can be varied by adjusting the position of the collar relative to the shaft. One function of the spring is to maintain the moveable shear blade in normally open position, except when it is being operated, and to return it to open-position when released by the operator at the end of a cutting stroke. A second function is to cause the cutting edge of the moveable blade tobear firmly but yieldably against the coacting cutting edge of the fixed blade during the cutting stroke as the contact point between the two moves across the tape. The shaft, at a point intermediate to its supports, carries an eccentric or cam 26 secured thereto by set-

screws

21 and 28. This cam coacts with an underlying switch actuating pin 29 (see Fig. 1), which projects vertically through the top base, and is arranged so that the pin will be held in pushed down position at all times except when the moveable shear blade is in or near closed position, at which time the cam permits the pin to be in raised position. The pin actuates a shear-controlled switching device (not shown, although symbolically indicated in Fig. 7) located below the top base and within the box, comprised of two single-pole one-way microswitches, one of which is in normally open position and the other .in normally closed position when the shear is in or near closed position, being held closed and open, respectively, at other times.

, Thus the operator causes these switches to be actuated in closing and opening the shear.

There is a supporting block 30, parallel to and spaced back from the supporting plate I3 and having a top surface slightly below that of the and extends forwardly with its front edge resting just behind the cutting edge of fixed shear blade l4. The\ table plate is straight-knurled longitudinally by means of a multiplicity of small ridges and grooves extending from the rear to the front edge, i. e., in the line of travel of tape moving forwardly above the plate to the shear. The knurling reduces adhesion of the adhesive tape to the table and minimizes sticking of the tape as it moves along. The front end portion of the table plate is slightly arched or humped, see 34, and just behind this portion the plate is slotted out to provide a series of spaced-apart rectangular. openings extending transversely across the plate, there being four such openings in the illustrated embodiment.

Below said openings there is a transverse driven roller shaft 35, the outer end of which is journaled in support 36 located to the'right of the table, having its axis parallel to the shear blade edges. The roller shaft is turned down so as to provide a series of small, short, spaced-apart, tape propelling and dispensing rollers 31, which project upwardly through the openings in the table plate, and one of which is at each side of the plate, thus making a total of six in the illustrated embodiment. These dispensing rollers are straightknurled longitudinally by a multiplicity of small ridges and grooves running parallel to the axis and hence atright angles to the knurling of the table plate. The top extremities of the rollers project slightly above the adjacent surface of the table plate and serve to grip the lower, tacky,

. face of the adhesive tape 38 for propelling it along during rotation of the roller shaft.

Immediately above and parallel to the roller shaft 35, thereis normally located an idle roller 39, having straight knurlings extending longitudinally, which presses yieldably against interposed adhesive tape and thus coacts with driven propelling rollers 31 by pressing the tape into positive operative engagement with the latter (see Fig. 5). An axle 40 passes through the bore of the idle roller and is journaled in the ends of the arms of the two supporting bell cranks 4| and 42, which are fulcrumed on the ends of spindle 43 which passes through supporting block 30, the other arm ends being fastened to loaded coil springs 44 and 45 which are attached to the rear part of the top base by screws 46 and 41. These springs thus function through the bell cranks to yieldably press the idle roller down, but the latter can be swung back when tape is to be threaded between the rollers. If desired, means can be provided for adjusting the tension of the springs so as to vary the pressure exerted by the idle roller to best accommodate various types of tape.

A box-like oil reservoir can 48 is located below the dispensing rollers 31 and against the rear of upright plate 13 (see Fig. 6), having a length somewhat greater than the width of the overlying table plate 3|. A wick 49, of suitable material such as cloth or felt, in the form of a tape or sheet having a width approximating that of the table plate, extends from the reservoir, passing through duct 50, which runs upwardly from the front and top of the oil reservoir can to just below the top of the upright plate, and the wick passes forwardly between thetable plate and the tops of the underlying upright plate and fixed shear blade to terminate with its edge directly above, and in alignment with, the cutting edge of the shear blade. When tape is cut, the operation is facilitated by the lubricating action of this wick, as hereafter explained in more detail. The oil reservoir can has a hole 5| in its top through which oil can be squirted for replenishment.

At the rear of the top base there is located a metal yoke 52, secured to the rear wall of the box, having arms extending rearwardly and upwardly' therefrom. This yoke serves as the support .and holder for the roll of adhesive tape being dispensed. The ends of the yoke arms are slotted to receive the projecting

hubs

53 and 54 of a wheel 55 upon the rim of which the core of the roll of adhesive tape 38 has been slipped. The yoke is so positioned and constructed that the adhesive tape roll is in alignment with the dispensing rollers and shear and the axis of the tape roll is about level with the top of the.

table plate. The roll of tape is inserted so that the tape will have the adhesive side down as it is drawn forward, and is located so that the tape normally Just clears, or rests lightly against, the top of the table plate as it is drawn from its roll by rotation of the dispensing rollers (see Figs. 1 and 2).

Referring now to the left hand side of the machine, which includes the driving unit and motor, the right end of driving shaft 60 fits into the left end of driven roller shaft 35 and is secured by set-screw 6| The middle of the driving shaft carries a worm wheel 62 which engages worm 63 on shaft 64 of a small electric motor 65, whereby speed reduction occurs (see Fig. This worm drive is contained in housing 86, which provides supporting journals for the driving shaft, and which is fastened to the front of the motor. The electric motor is of the universal type, adapted to operate on both alternat- I ing and direct current, and is mounted on the top base to the rear of the worm wheel so that its shaft lies above and crosses at right angles to the said driving shaft. The left end of driving shaft 60 extends beyond the housing and is threaded to receiv a friction wheel 61 having a rubber rim 68, the position of the wheel being adjustable since it can be screwed back and forth for some distance. A winged lock nut 69 is also carried by the driving shaft and can be screwed against the outer side of the friction wheel to lock it in the desired position.

, A driven cam shaft 10 runs to the rear, its axis approximately intersecting the left end of the driving shaft, at right angles, and carries on its front end a disk II which can be positioned to bear against the rubber rim of friction wheel 61. Thus by moving the friction wheel back and forth on the driving shaft, the turning ratio between the tWo shafts can be varied over a substantial range so that a variable ratio friction drive for driven cam shaft 10 is provided. The cam shaft is journaled in upright 12, located behind the disk, and in upright 13, located toward the rear of the top base. The rear end of the cam shaft terminates within upright 13. A screw 14 is threaded in from the rear of up right 13 and the two facing ends (of shaft '10 and screw 16) are cupped out and a bearing ball i5 is located therebetween. Screw It has a knurled head it and carries a knurled lock nut 11 to bear against the rear of upright 13, permitting ready adjustment. This screw permits of forcing driven shaft it! forward so that disk 1i will bear firmly against the friction wheel, and permits retraction of the disk when it is desired to adjust the position of the friction wheel.

Driven shaftil) carries an eccentric or cam 18, located between the two Journals, and which turns with the shaft to force down underlying vertical pin 19 just before the completion oi one turn. At the start of a cycle of operation of the dispenser, the pin is up and spaced from the camming surface. As the cam shaft turns, the camming surface remains clear of the pin .until Just before the end of the turn, and then depresses the pin for an instant before stopping,

box and serves for plugging in the machine to Cord any convenient electric outlet or socket. 82 connects to the rear of the motor and passes down into the box through a hole in the top for connection to the motor control system.

M ode of operation A roll of tape is placed in its holder, and the end is pulled toward the front oil/the machine and threaded between the rollers, the tacky adhesive side being underneath so as to contact the tape propelling rollers which project slightly above the corrugated table plate 3!. Different widths of tape can be used, since there are a number of such propelling rollers. As previously mentioned, the axis of the tape roll is located so that the tape as it approaches the rollers will just ,clear, or press only lightly against, the knurled table plate. This plate guides the tape so that it will be ejected from the rollers toward the shear. The humped or arched portion 34 at the front end of the plate prevents the ejected tape from pressing, or being pressed during the shearing step, against the table plate portion situated to the rear thereof and in front of the rollers. Thus there is a minimum of opportunity for the advancing tape to stick to the table plate, and the knurled surface of the latter further reduces frictional and stictional engagement of the tape.

The operator turns on the current by flipping toggle switch Bil, assuming that the dispenser has been plugged in, and is ready to begin.

He places the finger tips of one hand in the trough of the finger handle 22 of the movable shear blade 2i and presses downward with a quick movement, causing the shear to close, the projecting tape being cut off as the moving blade passes the resisting edge of fixed shear blade 14, The inner end of the severed piece of tape is carried down by the under surface of the moving shear blade and is pressed against the top of the underlying ledge H5 at the end of the stroke (see Fig. 4). The tacky adhesive adheres to the ledge and the piece of severed tape is temporarily held in position for convenient removal. During the cutting or shearing operation, the tape is pressed against the underlying end of oil wick 49 in advance of the angularly descending moving shear blade, thus squeezing out a small amount of oil upon the cutting edge portion and front face of the fixed blade, and upon the adhesive surface adjacent the cutting edge. The presence of this oil makes for an easy, clean cutting of the tape, including the adhesive coating thereof; and it prevents the adhesive from sticking to the shear blades, thus facilitating the pushing down of the inner end portion of the severed tape to the ledge,

fouled with adhesive material.

At the end of the down stroke of the moveable shear blade, the operator lifts his hand and the blade snaps back to normally open position. This same hand may then be used to grasp the dispensed piece of tape and remove it from its temporary support ready for application to a package or other article to be sealed or labelled, for example. J

As the moving shear blade starts to rise, the motor circuit is automatically closed and by the time the blade is out of the way the next unit length of tape will have started to move forward between the shear blades, being propelled by the dispensing rollers 31, which are driven by the motor as previously indicated. This will continue until cam shaft 10, driven by the motor through driving shaft 60 (which also drives the dispensing rollers) and the variable ratio friction drive, has made substantially one turn, whereupon the motor stops, leaving the predetermined unit length of tape projecting in posi tion for-cutting off. The desired length can be fixed in advance, as previously mentioned, by adjusting the position of friction wheel 61 (on the driving shaft) relative to the center of disk I! (on the cam shaft) so as to regulate the extent of rotation of the driven tape propelling rollers per turn of the cam shaft. The operation of the motor control system will be described hereinafter.

As previously mentioned, the basic machine can be readily modifiedas may be desired for use in connection with various kinds of adhesive tape. If a type of tacky, pressure-sensitive adhesive tape is employed which requires a relatively strong force to pull it from its roll, beyond the capacity of the dispensing roller device specifically illustrated, obviously an auxiliary pull drum can be interposed to be driven by the motor in suitable timed relation. Or the rollers can be increased in size, or a single roller used, arranged to afford a greater surface area to grip the adhesiv'e surface of the tape. If it is desired to dispense a non-tacky tape, such as the gummed paper form, the propelling rollers, or the coacting idle roller 39, or both, can be provided with rubber or other suitable surfaces to give increased traction if found necessary; and suitable guide means can be provided to properly direct the tape to the rollers. Since such gummed tape is non-tacky, the supporting ledge l6 can be modified so as to releasably hold the end of the severed tape. For example, a support having a row of prongs or teeth can be used, the under side of the moveable shear blade being recessed so that the blade will press the inner end portion of the tape into gripping engagement therewith. A moistening sponge device can be located to provide a fiat moistening surface extending forwardly of the temporary tape support, the operator pressing the severed piece of tape down against it and then pulling the tape up and off for sealing application.

Control system The circuit diagram of the electric control system is set out schematically in Fig. 7, and as the connections will be readily apparent upon inspection they will not be detailed, although indicated in the following description of mode of operation. The system works on either alternating or direct current.

When moveable shear blade 2| is in open position, the cam 26 on the shear blade shaft presses pin- 29 down so as to hold the normall closed single-pole one-way switch 90 in open position and the normally open single-pole one-way switch 9| in closed position. When the blade is pusheddown, and just before it reaches the end of the stroke, the cam permits pin 29 to rise so that switch 90 will close and switch 9| will open. And shortly after the blade is released and has started up. the cam again opens switch 90 and closes switch 9|. The switches are of a type which require but little motion of the actuating pin to cause opening and closing. and they are mechanically coupled' so as to be operated simultaneously by pin 29.

A relay is provided, of the kind which will function on either alternating or direct current, having a field coil 92, which when energizedholds the two normally open single-pole one-way switch units 99 and 94 in closed position.

A single-pole two-way switch is actuated by pin 19 which is depressed momentarily Just prior to the completion of each'turn of cam 18, on the cam shaft driven by the motor 65 through the variable ratio friction drive, as heretofore described. The nomially closed connection is designated 95, and the normally open connection is designated 9G.

' and to one terminal of relay field 001192, and it will be understood that tliese connections remain closed at all times during the operation of the dispenser, that is, until the line switch is opened. The connections between the other terminals and the other side of the line remain open at the beginning of the cycle of operation, but become closed as will now be described.

When the shear blade 2| nears the end of its down stroke, it'causes switch 90 to close, thus closing the current path through normally closed cam switch connection 95 to the previously disconnected terminal of the relay field coil. The latter is energized and closes relay switches 93 and 94, and switch 93 being shunted across 90, the opening of the latter will not break the field coil circuit. Switch 9| is now open and prevents the motor from starting.

As the shear blade starts upward, 90 opens without effect on the relay field coil (since 93 is now closed), and 9| closes to complete the motor circuit through closed relay switch 94. The motor causes tape to be dispensed and turns cam 18. Just before the latter completes one turn, it operates through pin 19 to momentarily open the cam switch connection 95, thereby breaking the connection to the relay field coil and causmg relay switches 93 and 94 to open. The opening of 94' breaks the motor connection therethrough, but the motor remains connected due to the simultaneous closing of cam switch connection 96 (which is connected across 94) and thus piovides power to turn cam 18 so that it clears pin 19 and allows the latter to rise. As soon as p.n I9 rises, 96 opens again, thus breaking the motor circuit and stopping the rotation of cam 18 and the rotation of the tape dispensing rollers. This completes the cycle of operation.

It may also be mentioned that since 96 is closed when relay switch 94 opens (the latter being in the motor circuit when closed), arcing of 94 is avoided, which is desirable since the simple type of relay which may be used leaves the switching contacts in the open within the box H, whereas the cam switches are purchased and installed as closed units. 4

It will be understood that the foregoing description of an embodiment of my invention has been given for purposes of illustration and not limitation.

What I claim is as follows:

1. In an adhesive tape dispenser, a normally open shearing means-for cutting off predetermined unit lengths of the tape, driven roller means adapted to propel the tape forwardly from a roll thereof to and through the open shearing means, means, for the controlled driving of said roller means including an electric motor, switching means actuated by the shearing means to start the motor upon the opening of the shearing means following the cutting off of tape and switching means actuated by the motor to stop the motor when the roller means has been driven sufilciently to propel a predetermined unit length of the tape in position for cutting'off by subsequent operation of the shearing means.

2. A device according to claim 1 in which the driven roller means for propelling the tape comprises a series of short rollers on a common driven shaft, a yieldable parallel idle roller pressing thereagainst and coacting with said rollers for propellin tape, and in combination therewith a table plate having openings through which said rollers on the driven shaft project, said table plate extending forwardly to the shearing means.

3. A device according to claim 1 in which the driven roller means for propelling the tape comprises a series of short rollers on a common driven shaft, a yieldable parallel idle roller pressing thereagainst and coacting with said rollers for propelling tapepassing therebetween, the surface of each roller having a straight knurling extending parallel to the axis, a table plate extending at right angles and having openings through which said rollers on the driven shaft project, said table plate extending in both directions from the rollers and the forward end terminating at the shearing means and being slightly arched, the surface of the plate having a straight knurling running longitudinally and at right angles to the knurling of the rollers, a fixed shear blade having its cutting edge near the forward end of said table plate, a moveable shear blade pivoted at one end of the fixed blade and spring means for holding the moveable blade in normally open position.

4. A device according to claim 1 in which the tape shearing means comprises a fixed shear blade over which the tape is propelled, a moveable shear blade pivoted at one end of the fixed blade, a handle on the moveable shear blade, a cam shaft rotated by the moveable blade and adapted to actuate switching means for starting the motor, and spring means for holding the moveable blade in normally open position.

5. A device according to claim 1 in which the tape shearing means comprises a fixed shear blade over which the tape is propelled, a moveable shear blade arranged to coact by pivoting past the fixed blade, and means for supplying oil to the cutting edge of the fixed blade and the overlying surface of the tape as the moveable shear blade cuts the tape.

6. A device according to claim 1 in which the tape shearing means comprises a, fixed shear blade over which the tape is propelled, a moveable shear blade arranged to coact by pivoting past the fixed blade and having a leading edge adapted to push the inner end portion of the severed piece of tape past the fixed blade, and holding means adapted to receive and releasably hold said inner end portion of the severed tape.

7. A device according to claim 1 having a fixed shear blade over which the tape is propelled, the outer side of ,the blade extending vertically downwards. from the cutting edge, an oil reservoir located to the rear of the blade and a fiat oilsupplying wick extending therefrom over the top of the blade and terminating at the cutting edge, a plate overlying the wick and having its forward edge just to the rear of the cutting edge so as to expose only the edge portion of the wick and support tape approaching the fixed shearing blade, a moveable shear blade arranged to cut tape by pivoting past the fixed blade and spring means for holding the moveable blade in normally open position above the fixed blade, a ledge located below the cutting edge of the fixed blade and on the outer side thereof adapted to receive and releasably hold the inner end portion of the severed piece of tape, the movable blade being arranged to push the inner end portion of the severed tape down from the cutting edge of the fixed blade and into engagement with the ledge.

8. A device according to claim 1 in which the controlled driving means includes a variable ratio drive and cam driven by the motor, said cam actuating switching means for stopping the motor, permitting adjustment of the rate of rotation of said cam relative to the rate of rotation of the driven roller means for propelling the tape and thus permitting predetermined adjustment of the unit length of tape to be dispensed.

9. A dispenser adapted to dispense predetermined unit lengths of normally tacky and pressure-sensitive adhesive tape from a roll thereof, comprising a base, a motor, a fixed shear blade having a horizontal cutting edge and a vertical front face located at the front of the base, a ledge located on the front face below the cutting edge, a moveable shear blade pivoted at one end of the fixed blade and located to swing down past the cutting edge of the fixed blade and meet the ledge, a finger handle on the moveable shear blade, spring means adapted to hold the shear in normally open position, a cam connected to the moveable shear blade to turn therewith and assoelated switching means arranged to automatically turn on the motor after the moveable shear blade completes a tape cutting operation, driven roller means located behind the fixed shear blade and adapted to propel adhesive tape to and over said blade with the adhesive side down, a holder for a roll of tape located behind said roller means to supply tape thereto, an oil wick overlying the top of the fixed shear blade and terminating at the cutting edge and an oil reservoir behind the blade into which the wick runs, a table plate extending rearwardly from said cutting edge and lying above the wick to guide tape from the driven roller means to the shear blade, driving means connected between said driven roller means and the motor to actuate the roller means so that tape will be propelled when the motor is running, a cam and associated switching means arranged to turn off the motor when the cam has been driven one turn, and driving means connecting the cam to the motor and adjustable to vary the speed of rotation of the cam in relation to the speed of rotation of the roller means used for propelling the tape whereby the predetermined unit length of tape dispensed can be varied.

10. In a dispenser adapted to dispense predetermined unit'lengths of normally tacky and pressure-sensitive adhesive tape from a roll thereof, a fixed shear blade and a coacting moveable shear blade, means for holding'the moveable blade in normally open' position, means for latter is pushed into engagement by the move- I able shear blade, the major portion of the severed tape projecting free from support in position to be grasped between the fingers for removal of the severed tape when desired.

11. In a, dispenser for normally tacky and pressure-sensitive adhesive tape, shearing means comprising a fixed shear-blade and a coacting moveable shear blade, spring means for holding the moveable blade in normally open position, an oil wick running from the rear of the fixed blade and terminating at the cutting edge thereof for lubricating the edge when tape is being cut, andcovering means overlying the wick and exposing only the edge portion at thecutting edge.

12. In a dispenser for normally tacky and pressure-sensitive adhesive tape, shearing means comprising a fixed shear blade and a coasting moveable shear blade, spring means for holding the moveable blade in normally open position, an oil wick running from the rear of the fixed blade is automatically followed by the advancement of a unit length of tape in position for cutting off upon subsequent operation of the shears so that successive manual operations of the shearing means results in the cutting off of a series of predetermined unit lengths of the adhesive tape as desired.

14. In an adhesive tape dispenser, shearing means including a movable element, tape drivin means adapted to propel the tape forwardly from a roll thereof to and through the shearing means,

and control means including means actuated by said movable element to automatically initiate operation of the tape'driving means following tape severing and also including means to auto- ;matically terminate movement of the tape when a predetermined unit length is positionedfor severing, so that each severing operation is autoa means to automatically terminate movement of and terminating at the cutting edge thereof for lubricating the edge when tape is being cut, covering means overlying the wick and exposing only the edge portion at the cutting edge, and a ledge located below the cutting edge of the fixed blade and adapted to receive and releasably hold the inner end portion of severed tape when the latter is pushed into engagement by the moveable shear blade.

13. In an adhesive tape dispenser, a normally open shearing means adapted for manual operation to cut off predetermined unit lengths of the tape, tape driving means adapted to propel the tape forwardly from a roll thereof to and through the open shearing means, and control means including means actuated by the shearing means to initiate operation of the tape driving means following tape severing and also including means toautomatically terminate movement of the tape when the predetermined unit length is positioned for cutting off, so that each severing operation matically followed by theadvance of a unit length of tape into position for severing.

, 1 5. In combination in a otor operated dispenser for normally tacky pr ure-sensitive adhesive tape, driving means for advancing tape from a roll thereof, tape severing means located to permit advanced tape to be cut off and including a movable element which moves when tape is severed, and control means including means actuated by said movable element to automatically initiate operation of the'tape-advancing means following tape severing and also including the tape when a predetermined unit length is positioned for severing, so that the severing of tape is automatically followed by the advance of a further predetermined length of tape into position for severing.

16. In combination in amotor operated dispenser for normally iy pressure-sensitive adhesive tape, driving eans for advancing tape from a rolithereof into position for severing a predetermined unit length, tape severing means located to permit advanced tape to be severed. and control means including means responsiveto the severing operation adapted to automatically cause operation of the tape-advancing means following tape severing and also including means to automatically terminate movement of the tape when a predetermined unit length is positioned for severing, so that the severing of tape is automatically followed by the advance of a further predetermined length of tape into position for severing.