US3479485A

US3479485A - Heat sealer

Info

Publication number: US3479485A
Authority: US
Inventors: William L Hanna; Christian C Petersen
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1966-10-12
Filing date: 1966-10-12
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18

Description

Nov. 18, 1969 w. HANNA ET AL 3,479,485

HEAT SEALER Filed Oct. 12. 1966 z Sheets-Sheet 1 fee INV N O W T RS 68 BY zmmzwwm Fl G. 4

J. W ATTORNEYS Nov. 18, 1969 w, HANNA ET AL 3,479,485

' HEAT SEALER Filed Oct. 12; 1966 3 S heets-Sheet 2 Fl G 2 1N I W MZFVENTOR BY l/uzafimlm United States Patent HEAT SEALER William L. Hanna, Foxboro, and Christian C. Petersen,

Westwood, Mass., assignors to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Filed Oct. 12, 1966, Ser. No. 586,271

Int. Cl. Hb 3/02 US. Cl. 219-243 Claims ABSTRACT OF THE DISCLOSURE A heat sealing apparatus having a base, a sealer block and an opposed heater arm mounted on the base. The heater arm is provided with a resistance heater element. The heater arm is movable relative to the sealer block by a motor driven cam. A control circuit is provided for the apparatus which includes a motor for driving the cam and a material-actuated start switch for starting the motor. The motor is provided with a dynamic breaking circuit to terminate rotation of the cam at the completion of one cycle.

This invention relates to heat sealing apparatus and in particular to apparatus for sealing or joining sheets of heat fusible materials. A particulary useful application of the invention is the automatic heat sealing of an edge of a plastic pouch designed to hold an identification card.

The plastic pouches as supplied may consist of two sheets of rectangular thermoplastic material superposed over one another and sealed along three edges with one of the edges left open so that an identification card may be inserted before the fourth edge is sealed.

The pouch performs a protective function for the identification card both against the weather and the wear and tear of repeated handling.

The sealer of the present invention may be utilized as part of an identification card system wherein a specially designed identification camera is used to make a color print (employing the well known Land system of photography) in one minute including a picture of an individual and printed identification data. The print is then directed through an automatic laminator and a die-cutter which takes about another 50 seconds and the card is ready to be inserted in its individual pouch and the pouch sealed. A very important criteria for design of the present invention is the ability to seal the pouch automatically and in as short a time as possible so that in about two minutes after sitting in front of the camera a person may receive his completed identification card sealed in its plastic pouch.

Other important aspects of the invention for accomplishing this high speed operation are: (1) the pre-heating of the heater element so it is always at the proper temperature for the particular heat fusible material being used and (2) the automatic operation of the device including an actuating mechanism tripped by insertion of the pouch into an opening provided.

While the present device is disclosed and utilized in an identification card system for sealing the open edge of plastic pouches it is recognized that the device may have other applications and may in fact be utilized whenever the quick edge sealing of two or more heat fusible sheets is required. It is obvious that changes may be made, for example, in the size of the device or the temperature of the heating element to handle different sizes and kinds of materials to be heat fused.

Accordingly, it is an object of this invention to provide a sealer for joining sheets of heat fusible material.

It is another object of this invention to provide a heat sealer which can automatically seal the open edge of a "ice plastic pouch within a short period of time (i.e. 3 to 4 seconds).

It is still another object of this invention to provide a heat sealer which is highly effective and yet simple in structure and operation and inexpensive to manufacture.

Other objects of this invention will in part be obvious and'will in part appear hereinafter.

The invention comprises the apparatus possessing the construction combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be i ndicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the acconipanying drawings wherein:

FIGURE 1 is a perspective view of the apparatus embodying the invention with the cover partly broken away toshow the internal mechanism;

FIG. 2 is a sectional view taken along line 22 in FIG. 1;

FIG. 3 is a view as seen in the direction of arrows 33 in FIG. 1; and

FIG. 4 is a schematic wiring diagram of an electrical control system useful in the practice of this invention.

Referring to FIGURE 1, there is shown an identification card pouch sealer mechanism which includes a base 10 having two side walls and a back wall. The base supports sealer block 11 which is positioned under the heater block 12 so that when the pouch is inserted through chute 13 it may be clamped and sealed between the heater and sealer blocks.

As shown in FIG. 2, the heater block 12 carries a heating element 14 received in a groove in insulating block 15 and covered by a Teflon-glass heater fabric 16. The fabric is clamped to the front and back of the heater block by

clamp plates

17 and 18 mounted on the heater block by

screws

19 and 20. The heater block is supported on heater arm 21 which as shown in FIG. 2 has a pair of bent portions 22 (only one being illustrated) which are pivotally supported on pins journaled in the side walls of base 10. A spring 24 urges the heater arm 21 in an upward direction where it assumes the position shown in broken lines in FIG. 2.

The heater arm has a deformed portion 25 which contacts cam 26 and is biased against said cam by the spring 24. The cam as shown in FIG. 3 has a recessed portion 23 and at the start of the cycle the deformed portion 25 of the heater arm is received in the recessed portion of the cam which permits the spring 24 to bias the heater arm in its upward position. At this point in its cycle the cam is said to be in its dwell position. The cam 26 is mounted on collar 27 by means of roll pin 28, as shown in FIG. 2. The collar 27 in turn is mounted on shaft 29 by means of set screw 30. A conventional motor and gearing system is mounted in housing 31 and drives cam carrying shaft 29. During each sealing operation or cycle the cam 26 rotates a full 360 degrees.

The motor which drives the cam 26 is actuated by start switch 35 which is mounted on the base in close proximity to one end of lever 37. Lever 37 is pivotally connected to flange 38 on plate 40 connected to the side walls of base 10. The other end of said lever extends into the area between the heater and sealer blocks so that when the pouch is inserted beneath the heater element it contacts lever 37 which pivots and trips starter switch 35. The lever 37 is shown in FIG. 2 with broken lines in its rest position and with solid lines when it is pivoted against stop plate 42. There are shallow grooves in sealer block 11 to receive the ends of lever 37 in its rest position. The other end of lever 37 has a pair or prongs 43 and 44. Prong 44 trips starter switch 35 and the switch element 3 45 is spring biased which maintains lever 37 in said rest position. The other prong 44 engages element 48 of reset switch 50, the function of which will be explained later.

After the scaling is accomplished, it is necessary to stop the cam so that the recessed portion 23 is in a position to receive the deformed portion 25 of the heater arm, thereby allowing the heater arm to be biased in its upward position whereby heater element 14 is separated from sealer block 11 and the sealed pouch may be removed. To accomplish this result a brake switch 51 is provided. The brake switch 51 is connected through circuitry to a dynamic braking circuit which discharges through the motor winding 62 and brings the motor with its shaft carried cam 26 to an abrupt halt (within 3 of travel of its output shaft) with the cam in its dwell position, allowing the heater arm to be biased in its upward position. Said brake switch is tripped by means of a follower 53 which rides on cam surface 54 as shown in FIG. 1. The cam surface is designed so that immediately prior to the end of the 360 rotation of the cam the follower trips said brake switch 51.

It is also desirable to prevent the cam 26 from recycling unless the pouch is completely removed and reinserted. To accomplish this the aforementioned reset switch .50 is provided. To explain the operation of the reset switch, it is necessary to describe the simple circuit of the device which is shown in FIG. 4.

The circuit consists of an alternating current source which provides the power to transformer 60. The power output of transformer 60 provides current to the heating element 14 and maintains the heating elementat a predetermined temperature so long as alternating current is being supplied to the device. The alternating current source also supplies current to the winding 62 of the motor which drives cam shaft 29. The start switch-35 and the reset switch 50 are connected in series to the motor. When the brake switch is in the XY position it provides an alternate path, if either the start or reset switch is in the open position, to both the motor and the capacitor 64 for charging purposes. When the brake switch is moved to the YZ position the capacitor 64 is allowed to discharge into the motor winding providing the braking action. Also included in the circuit is diode 66 which permits only the positive half cycle of the alternating current source to charge the direct current capacitor 64. Diode 69 provides a short circuit to any negative spikes of current which might otherwise appear across direct current capacitor 64 at the moment when the capacitor is discharged through motor winding 62 to provide the braking action. The capacitor 64 is discharged through current limiting resistor 69 and another resistor 70 is provided in the RC timing network for charging said capacitor 64.

In operation, first the start switch is closed by activation of lever 37. The projection 72 on the end face of cam 26 opens the reset switch when the cycle is approximately 50% complete. Before this happens and with of rotation of cam 26 the brake switch 51 is moved by means of cam follower 53 from the YZ to the XY position, providing an alternate current path, so that even after the reset switch is opened, the motor continues to run. When the cycle is almost complete the cam through cam follower 53 allows the brake switch to move to the YZ position. This action removes the alternating current from the motor winding and allows the capacitor 64 to discharge into the motor winding 62 providing the braking action. When the pouch is removed from the chute 13 sealer lever arm 37 is free to pivot in a counter clockwise direction opening the start switch, and moving the reset switch to its closed position.

Another feature of the invention is the iron coil resistor 74 shown in the circuit in series with the heater filament 14, FIG. 4. Transformer 60 converts the line voltage to the proper volt-age to be applied across heater element 14.

However, it has been found that the line voltage in many areas is not constant but may vary, for example, in the range between 105-130 volts. As the voltage surges toward and beyond 130 volts, the heater element tends to overheat and might melt the edge of the plastic pouch instead of sealing it. To prevent variations in line voltage from effecting the operation of the device, the iron coil 74 is incorporated into the heater element circuit and prevents the voltage in the heater element 14 from varying greater than a predetermined amount. The iron coil has the characteristic that its resistance becomes greater as it heats up due to an increase in voltage applied to the circuit and this increase in resistance will keep the voltage applied to the heater element within its top effective limit. At lower voltage levels the cooler iron coil will have a relatively low resistance and will allow sufiicient current to flow in the heater element circuit for eflicient operation.

The final feature to be described is a chute divider, shown in FIGS. 1 and 3, having two

arms

76 and 77 which serve as a guide for the pouch when its shorter dimension is inserted into the sealer. Provision is made to remove the chute divider through slots in the bottom 79 of chute 13. This includes plate 78 integral with the chute dividers and having a hand operated portion 80 with which the plate carrying the chute dividers may be moved up and down. To maintain plate 78 in its chute dividing position, a member 81, shown in FIG. 3, is formed having a slot 82 with a shoulder 83. A portion 84 of plate 78, shown in FIG. 2, is bent at a right angle from the plane of the plate and is moved up and down in slot 82 and rests on shoulder 83 when plate 78 is in the up position. A washer 85 and cotter pin 86 prevent the portion 84 from slipping out of slot 82. The coil spring 88 which has one end engaging another small bent away portion 90 of plate 78 and the other end engaging portion 84 exerts a bias on said latter portion to prevent it from slipping off shoulder 83.

Since certain changes may be made in the above device without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A device for joining sheets of heat fusible material comprising:

a base;

a heater arm pivotably mounted on said base and movable between a first and a second position;

an electrically powered heater element carried by said heater arm, said heater element being maintained at a predetermined temperature required to fuse said sheets;

a sealer block mounted on said base in proximity to said heater element so that movement of said heater arm from its first to its second position clamps said heat fusible sheets between said heater element and said sealer block;

a rotary electric motor having a winding and a rotor mounted on said base;

a rotatable disc shaped cam driven by said motor having a peripheral cam surface;

a cam follower portion on said heater arm;

a spring, biasing said pivoted heater arm, and said cam follower portion against said peripheral cam surface so that during each cycle of cam rotation the heater arm is moved between its first and second position;

a capacitor in circuit with the winding of said electric motor;

a start switch in said circuit for connecting said winding and said capacitor to a power source;

a pivoted actuating lever having one end positioned adjacent the sealer block and the other end adjacent said start switch so that insertion of said sheets of heat fusible materials between the heater element and sealer block will cause said lever to trip said start switch and connect said motor winding and said capacitor to the power source for energizing said motor and charging said capacitor; and

means operable in response to one revolution of said cam to disconnect said winding of said electric motor and said capacitor from said power source and to maintain said winding in circuit with said capacitor such that said capacitor discharges through said winding to establish a magnetic force in said electric motor to terminate rotation of the rotor thereof and thus terminates the rotation of said cam.

2. A device for joining sheets of heat fusible materials comprising:

a base;

a heater arm mounted on said base;

a heater element carried by said heater arm;

means for maintaining said heater element at a predetermined temperature required to fuse said sheets;

a sealer block mounted on said base in proximity to said heater element, said heater element and said sealer block being relatively movable so that in a first position said heater element is spaced a distance greater than the combined thickness of said heat fusible sheets from said sealer block and in .a second position said heat fusible sheets are clamped between said heater element and said sealer block;

start switch means tripped by insertion of said heat fusible sheets between said heater element and said sealer block;

means activated by said start switch means to cause relative movement between said heater element and said sealer block between said first and second positions comprising:

.a rotatable driven cam having a first peripheral cam surface;

a cam follower portion on said heater arm biased by said first peripheral cam surface;

a motor having a winding for driving said cam; and

a dynamic braking circuit to terminate rotation of said cam at the completion of one cycle including a capacitor and means for discharging a charge on said capacitor through the winding of the motor driving said cam.

3. The invention according to claim 2 wherein a brake switch means is provided to activate said dynamic braking circuit, said brake switch means comprising:

a second peripheral surface on said rotatable driven cam; and

a cam follower biased against said second peripheral cam surface, said second peripheral cam surface being so formed as to cause said cam follower to trip said brake switch immediately prior to the completion of one cycle of cam rotation.

4. A device for joining sheets of heat fusible materials comprising:

a base;

a heater arm mounted on said base;

a heater element carried by said heater arm;

a sealer block mounted on said base in proximity to said heater element, said heater element and said sealer block being relatively movable so that in a first position said heater element is spaced a distance greater than the combined thickness of said heat fusible sheets from said sealer block and in a second position said heat fusible sheets are clamped between said heater element and said sealer block;

start switch means tripped by insertion of said heat fusible sheets between said heater element and said sealer block including a pivoted lever having one end positioned adjacent the sealer block and the other end adjacent said start switch means such that insertion of said sheets of heat fusible material between the heater element and sealer block causes said lever to, pivot and trip said start switch means; and

means activated by said start switch means to cause relative movement between said heater element and said sealer block between said first and second positions.

5. A device for joining sheets of heat fusible materials comprising:

a base;

a heater arm mounted on said base;

a heater element carried by said heater arm;

means activated by said start switch means to cause relative movement between said heater element and said sealer block between said first and second positions; and

a chute mounted on said base and positioned adjacent said sealer block to guide said heat fusible sheets between said heater element and said sealer block.

6. The invention according to claim 5 wherein means are provided to selectively divide said chute, said means comprising:

a pair of arms mounted on a slidable plate;

a manually operated portion on said plate to slide said plate between a position where the pair of arms extend through slots in said chute to divide said chute; and

a position where said pair of arms are removed from said chute.

7. A device for joining sheets of heat fusible materials comprising:

a base;

a heater arm mounted on said base;

a heater element carried by said heater arm;

a sealer block mounted on said base in proximity to said heater element, said heater element and said sealer block being relatively movable so that in a first position said heater element is spaced a distance greater than the combined thickness of said heat fusible sheets from said sealer block and in a second position said heat fusible sheets are clamped betwen said heater element and sealer block;

start switch means tripped by insertion of said heat fusible sheets between said heater element and said sealer block; and

means activated by said start switch means to cause relative movement between said heater element and said sealer block between said first and second positions, said means including:

a rotatable driven cam having a surface maintained in contact with said heater arm; and

a cam follower portion on said heater arm biased by said cam surface.

8. A heat sealer comprising:

abase;

a heater arm mounted on said base;

a heater element carried by said heater arm;

a sealer block mounted on said base in proximity to said heater element, said heater element and said sealer block being relatively movable between a release position wherein said heater element is spaced from said sealer block and a clamping position to clamp sheets of heat fusible material between said heater element and sealer block;

a start switch tripped by insertion of heat fusible material between said heater element and said sealer block; and

means activated by said start switch to cause relative movement between said heater element and said sealer block between said release and clamping positions, said means including:

a rotatable driven cam having a cam surface, said surface having a recess therein;

means for maintaining said heater arm in contact with said cam surface; and

a cam follower portion on said heater arm biased by said cam surface for urging said heater element carried by said heater arm into said clamping position, said cam follower portion being received in said recess in said cam surface for returning said heater element to said release position.

10. The invention according to claim 7 wherein the heater element is electrically powered further comprising:

References Cited UNITED STATES PATENTS 3,023,295 2/1962 Johnson 219237 X 3,106,630 10/1963 Klamp 219-243 X 3,219,794 11/1965 Mindell et al. 2192l6 3,375,777 4/1968 Techtmann et al. 219243 0 JOSEPH v. TRUHE, Primary Examiner C. L. ALBRITT ON, Assistant Examiner 9. A heat sealer as described in claim 8 wherein said means for maintaining said heater arm in contact with said cam surface comprises a spring.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,479,485 November 18, 1969 William L. Hanna et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 72, "44" should read 43 Column 3, line 47, 69" should read 68 line 58, "with" should read within Column 6, line 2, after "to" cancel the comma. Column 8, line 7, "preventhig" should read preventing Signed and sealed this 16th day of February 1971.

(SEAL) Attest:

WILLIAM E. SCHUYLER, IR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer