Note: Descriptions are shown in the official language in which they were submitted.
CA 02279688 1999-08-OS
HAND-HELD ELECTRIC SEALER WITH SAFETY DEVICE
BACKGROUND OF TH iNV~NTION
The present invention relates to electric sealers, and more particular to a
hand-held electric sealer, and more particularly to a hand-held electric
sealer with a safety
device that controls the heating of the sealing mechanism, and stops the
sealing mechanism
from being triggered accidentally.
A variety of electric sealers have been developed, and have appeared on the
market. These conventional electric sealers are designed to be energized by AC
power
supply, or DC power supply. US Pat. No. 5,142,123 discloses an electric sealer
energizable
by internal battery set or external AC adapter.
SUMMARY OF THE PREFBRR EMBODIM NTS
It is the object of the present invention to provide an electric sealer which
is
hand-held, and safe to use. It is another object of the present invention to
provide an
electric sealer which a hand-held electric sealer which is energizable by
internal battery set
or external AC adapter. It is still another object of the present invention to
provide a hand-
held electric sealer which has means to stop the sealing mechanism from being
triggered
accidentally.
According to one aspect of the present invention, the hand-held electric
sealer
comprises a casing, a sealing mechanism, a press bar, and safety means. The
sealing
mechanism comprises a heat insulative base, a heating wire, and two metal
locating plates.
The heat insulative base has a projecting block on the middle. The heating
wire is mounted
on the projecting block of the heat insulative base. The metal locating plates
are fastened
to the heat insulative base at two opposite sides to hold down the heating
wire. A heat
resistant cover sheet may be fastened to the projecting block of the heat
insulative base,
and covered on the heating wire. There may be more than one heating wire if
desired. The
heat insulative base of the sealing mechanism can be made of ceramics,
Bakelite, heat
insulative plastics, or any material that resists heat as high as about
200°C. The press bar
has one end, namely the fixed end, pivoted to the casing, and an opposite end,
namely the
free end, with a heat insulative block mounted thereon. When the press bar is
pressed
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CA 02279688 1999-08-OS
down, the heat insulative block is lowered with the free end of the press bar
and forced
against the heat insulative base of the sealing mechanism to clamp the mouth
of the plastic
bag, enabling the mouth of the plastic bag to be sealed. The safety means
controls the
heating of the heating wire of the sealing mechanism, and stops the sealing
mechanism
from being triggered accidentally. The safety means can be a stop plate
pivoted to the
outside wall of the casing, and turned between a first position where the stop
plate is
suspended above the sealing mechanism to stop the heat insulative block of the
press bar
from contacting the projecting block of the heat insulative base of the
sealing mechanism,
and a second position where the stop plate is moved away from the sealing
mechanism for
enabling the heat insulative block of the press bar to be pressed against the
projecting block
of the heat insulative base of the sealing mechanism. In another embodiment of
the present
invention, the safety means includes a shaft mounted in a hole inside the
casing, a stop rod
and extended out of a notch on the casing and operated by hand to turn the
stop rod about
the shaft between a fig st position where the sealing mechanism cannot be
triggered, and a
second position where the sealing mechanism can be triggered. The safety means
can be a
safety switch, a press-button switch, or an electric connector, or a
combination thereof.
When a press-button switch is used, a protective shielding means is provided
for protection.
The electric circuit is closed or opened by means of operating the safety
means of the
safety switch, press-button switch or electric connector. In still another
embodiment of the
present invention, the sealing mechanism is installed in the free end of the
press bar.
According to another aspect of the present invention there is provided a hand-
held electric sealer including a housing, a sealing mechanism, a heat
resistant cover sheet
and a press unit pivotally connected to the housing that acts against the
sealing mechanism.
The sealing mechanism is mounted in the housing and includes a heat insulative
base having
a protrusive portion and an electric heating wire mounted on the protrusive
portion of the
heat insulative base. The heat resistant cover sheet covers at least a portion
of the electric
heating wire and is held within a frame. The frame includes retainer means
that engage the
protrusive portion of the heat insulative base to secure the heat resistant
cover sheet to the
protrusive portion and over at least the portion of the electric heating wire.
According to another aspect of the present invention there is provided an
electric sealer comprising a housing, a sealing mechanism mounted within said
housing, a
frame having defined therein an opening having an edge that is aligned with at
least a
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portion of the sealing mechanism, and a heat resistant cover sheet aligned
with at least a
portion of the opening in said frame.
According to yet another aspect of the present invention there is provided an
electric heat sealer comprising a casing, a sealing mechanism mounted and
movable upward
and downward within the casing, the sealing mechanism includes an electric
heating wire
through which electrical current flows, operating means for activating the
sealing
- mechanism, and a safety device that selectively prevents electrical current
from flowing
through the electric heating wire.
Other objects, features and advantages of the present invention will become
apparent to those skilled in the art from the following detailed description.
It is to be
understood, however, that the detailed description and specific examples,
while indicating
preferred embodiments of the present invention, are given by way of
illustration and not
limitation. Many changes and modifications within the scope of the present
invention may
be made without departing from the spirit thereof, and the invention includes
all such
modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an exploded view of a hand-held electric sealer according to a
first
embodiment of the present invention.
Figure 2 is a perspective view of the first embodiment of the present
invention.
Figure 3 is a cross sectional view of the first embodiment of the present
invention, showing the press bar not depressed.
Figure 4 is similar to Figure 3 but showing the press bar depressed.
Figure 5 is an exploded view of a hand-held electric sealer according to a
second embodiment of the present invention.
Figure 6 is an exploded view of a hand-held electric sealer according to a
third
embodiment of the present invention.
Figure 7 is a top plain view of the third embodiment of the present invention,
showing the arrangement of the electric circuit.
Figure 8 is a sectional view of a part of the first embodiment of the present
invention, showing an. AC adapter inserted into the electric connector, the
second terminal
disconnected from the first terminal.
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Figure 9 is an exploded view of a hand-held electric sealer according to a
fourth embodiment of the present invention.
Figure 10 is a top plain view of the fourth embodiment of the present
invention, showing the arrangement of the electric circuit.
Figure 11 is an exploded view of a hand-held electric sealer according to a
fifth embodiment of the present invention.
Figure 12 is an exploded view of part of Figure 1 1 .
Figure 13 is a schematic drawing showing the safety switch of the fifth
embodiment of the present invention operated.
Figure 14 is an exploded view of a hand-held electric sealer according to a
sixth embodiment of the present invention.
Figure 15 is a perspective view of the sixth embodiment of the present
invention.
Figure 16 is another perspective view of the sixth embodiment of the present
invention when viewed from another angle.
Figure 17 is an exploded view of a hand-held electric sealer according to a
seventh embodiment of the present invention.
Figure 18 is an exploded view of a hand-held electric sealer according to an
eighth embodiment of the present invention.
Figure 19 is an exploded view showing the detachable arrangement of the
sealing mechanism according to the present invention.
Figure 20 is a sectional view of an alternate form of the present invention,
showing the sealing mechanism installed in the free end of the press bar.
Figure 21 is similar to Figure 20 but showing the press bar depressed.
Figure 22 is an exploded view of the sealing mechanism for a hand-held
electrical sealer according to another embodiment of the present invention.
Figure 23 is a schematic drawing explaining replacement of the heat resistant
cover sheet in the embodiment of Figure 22.
Figure 24 shows an alternative form of the heat insulative base according to
the present invention.
Figure 25 shows an alternate form of the frame and another alternate form of
the heat insulative base according to the present invention.
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Figure 26 shows another alternate form of the frame and its positioning on
the front cover plate relative to the heat insulative base according to the
present invention.
Figure 27 shows multiple electric heating wires disposed on the heat
insulative base of Figure 24 according to the present invention.
Like numerals refer to like parts throughout the several views of the
drawings.
DETAILED DESK'-RIPTION OF THE PREFFRRFn Ft~nanniMENTS
Referring to Figures 1 through 4, a hand-held electric sealer in accordance
with a first embodiment of the present invention is an electric sealer
energizable by an
internal battery set. The sealer includes a casing 10, a spring holder 1 1, a
press bar 20, a
battery chamber 30, and a sealing mechanism 40.
The battery chamber 30 is defined within the casing 10, and includes a front
contact holder 31 transversely disposed at a front side, a rear contact holder
32
transversely disposed at a rear side, a pair of first metal contacts 33 and 34
bilaterally
provided at the front contact holder 31, a pair of second metal contacts 35
bilaterally
provided at the rear contact holder 32, and two horizontal metal contacts 331
and 341
respectively forwardly extended from the first metal contacts 33 and 34.
According to this
embodiment, the second metal contacts 35 are integral with each other. A
battery set can
then be installed in the battery chamber 30 between the front contact holder
31 and the
rear contact holder 32 to provide DC power to the sealing mechanism 40. The
spring holder
11 is mounted in casing 10 between the horizontal metal contacts 331 and 341.
The sealing mechanism 40 is mounted in the casing 10, and includes a heat
insulative base 41, a heating wire 42, two metal locating plates 43, a heat
resistant cover
sheet 44, and a compression spring 45. The heat insulative base 41 comprises a
flat
projecting block 41 1 on the middle. The heating wire 42 is fastened to the
projecting block
41 1 of the heat insulative base 41. The locating plates 43 are fastened to
the heat
insulative base 41 at two opposite sides to hold the heating wire 42 in place.
The heat
resistant cover sheet 44 is covered on the projecting block 411 and the
heating wire 42 to
protect the heating wire 42, and to provide a smooth surface. The heat
resistant cover
sheet 44 can be a meshed member made of teflon-coated metal wire. The heat
insulative
base 41 further comprises a bottom hole 412. The compression spring 45 has a
bottom
end mounted in the spring holder 1 1 and a top end inserted into the bottom
hole 412.
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Therefore, the sealing mechanism 40 is supported on the compression spring 45,
and can be
moved up and down relative to the casing 10.
The press bar 20 comprises a heat insulative block 21 at the bottom side of
one end, namely the front end thereof, a heat resistant cover sheet 22 covered
on the heat
insulative block 21, and a pair of lugs 23 bilaterally arranged in parallel at
an opposite end,
namely the rear end thereof. The lugs 23 each have a pivot pin 231. The pivot
pins 231 of
the lugs 23 are respectively inserted into respective pivot holes 12 at the
rear side of the
casing 10 remote from the sealing mechanism 40. Therefore, the press bar 20
can be
pivoted up and down about an axis relative to the casing 10. When the press
bar 20 is
pivoted downwards, the heat insulative block 21 is pressed on the projecting
block 41 1 of
the heat insulative base 41 of the sealing mechanism 40. The heat resistant
cover sheet 22
is covered on the heat insulative block 21 to provide a smooth surface. The
heat resistant
cover sheet 22 can be a meshed member made of teflon-coated metal wire.
Further, a
spring plate 24 is provided, having a fixed end fastened to the press bar 20
and a free end
stopped at a part of the casing 10. The spring plate 24 imparts an upward
pressure to the
press bar 20, causing the press bar 20 to be maintained in an "opened"
position where the
heat insulative block 21 is kept away from the projecting block 411 of the
heat insulative
base 41 of the sealing mechanism 40.
A safety stop plate 14 is pivotally connected to the front side of the casing
10. When the heat sealer is not in use, the safety stop plate 14 is pivoted
upwards and
forced into the gap between the heat insulative block 21 of the press bar 20
and the
projecting block 411 of the heat insulative base 41 of the sealing mechanism
40 to prohibit
the heat insulative block 21 of the press bar 20 from contacting the sealing
mechanism 40.
When in use, the safety stop plate 14 is pivoted outwards and then downwards,
enabling
the heat insulative block 21 of the press bar 20 to be pressed against the
projecting block
41 1 of the heat insulative base 41 of the sealing mechanism 40.
A cover 50 is covered on the casing 10 to protect the sealing mechanism 40
and the battery chamber 30. The cover 50 is comprised of a front cover plate
51, which
covers the sealing mechanism 40, a battery cover plate 52, which covers the
battery
chamber 30, and a rear cover plate 53, which covers the rear part of the
casing 10. The
front cover 51 has an opening 511 through which the projecting block 41 1 of
the heat
insulative base 41 of the sealing mechanism 40 passes.
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CA 02279688 1999-08-OS
Further, a magnetic mounting plate 13 is fixedly provided at the back side
(bottom side) of the casing 10. By means of the magnetic mounting plate 13,
the hand-held
electric sealer can be secured to a metal object, for example the metal wall
of a refrigerator,
by magnetic attraction.
The operation of the first embodiment of the present invention is outlined
hereinafter with reference to Figures 3 and 4 again. As illustrated in Figure
3, when the
hand-held electric sealer is not in operation, the metal locating plates 43
are kept away from
the horizontal metal contacts 331 and 341, the heating wire 42 is disconnected
from the
DEC power supply of the battery (which is installed in the battery chamber
30), and the
safety stop plate 14 is stopped between the heat insulative block 21 of the
press bar 20
and the projecting block 411 of the heat insulative base 41 of the sealing
mechanism 40.
Therefore, pressing the press bar 20 does not cause the sealing mechanism 40
to work.
When in use, as illustrated in Figure 4, the safety stop plate 14 is turned
away from the
projecting block 411, then the press bar 20 is depressed to force the heat
insulative block
21 against the heat insulative base 41 of the sealing mechanism 40, causing
the metal
locating plates 42 to be lowered with the heat insulative base 41 into contact
with the
horizontal metal contacts 331 and 341, and the heating wire 42 is electrically
connected to
start the heat sealing operation.
When sealing the two thermoplastic flaps of an article, the thermoplastic
flaps
of the article are placed in between the heat insulative block 21 and the
projecting block
41 1, then the press bar 20 is depressed to force the metal locating plates 43
into contact
with the horizontal metal contacts 331 and 341. When the metal locating plates
43 touch
the horizontal metal contacts 331 and 341, the heating wire 42 is turned on to
produce
heat, thereby causing the thermoplastic flaps of the article to be sealed.
After sealing, the
press bar 20 is released, enabling the heat insulative base 41 and the metal
locating plates
43 to be moved upwardly away from the horizontal metal contacts 331 and 341 by
the
compression spring 45, and therefore battery power is cut off from the heating
wire 42.
Figure 5 shows a hand-held electric sealer according to a second embodiment
of the present invention. This embodiment is energizable by an external AC
adapter. The
structure and operation procedure of this second embodiment are similar to
that of the first
embodiment with the exception of the arrangement of the power supply. The
second
embodiment comprises a power socket 70 for receiving power from an AC outlet
through an
AC adapter. The power socket 70 has two opposite terminals respectively
connected to the
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CA 02279688 1999-08-OS
horizontal metal contacts 331 and 341 by electric wires 72 and 73. Because no
battery is
used, the aforesaid battery chamber can be eliminated from the casing 10.
Therefore, the
size of the casing 10 can be greatly reduced. Further, the safety stop plate
14 is pivotally
connected to the outside wall of the casing 10 relative to the sealing
mechanism 40 for
safety control.
Figures 6 through 8 illustrate a hand-held electric sealer according to a
third
embodiment. This third embodiment can be energized by an internal battery set
or an
external AC adapter as desired. The electric connector, referenced by 90,
comprises a first
terminal 91, a second terminal 92 and a third terminal 93 respectively
connected to the left-
side first metal contact 33 and the two horizontal metal contacts 331 and 341
by
respective electric wires 71, 72 and 73. The left-side horizontal metal
contact 331 and the
left-side first metal contact 33 are separated from each other. The right-side
horizontal
metal contact 341 and the right-side first metal contact 34 are connected
together. As
illustrated in Figure 7, the first terminal 91 and the second terminal 92 are
electrically
connected. When an AC adapter 80 is connected to the electric connector 90,
the second
terminal 92 is forced away from the first terminal 91 (see Figure 81, i.e.,
the battery is off
after installation of the AC adapter 80 in the electric connector 90.
Therefore, at any one
time, only battery power or AC power is exclusively provided to the sealing
mechanism.
The third embodiment further comprises a safety switch 60 installed in the
electric wire 72 between the second terminal 92 of the electric connector 90
and the left-
side horizontal metal contact 331. When not in use, the safety switch 60 is
switched to
the off position to cut off the power supply. Under this condition, pressing
the press bar 20
does not cause the sealing mechanism to work. Because the safety switch 60 can
easily be
achieved by conventional techniques, it is not described in detail.
Figures 9 and 10 illustrate a hand-held electric sealer according to a fourth
embodiment of the present invention. According to this embodiment, the right-
side
horizontal metal contact 341 and the right-side first metal contact 34 are
separated from
each other, the first terminal 91 is connected to the left-side first metal
contact 33 by one
electric wire 71, the second terminal 92 is connected to the left-side
horizontal metal
contact 331 by one electric wire 72, the third terminal 93 is connected to the
right-side
horizontal metal contact 341 by one electric wire 73, and the safety switch 61
is installed in
an electric wire 74, which is connected between the right-side first metal
contact 34 and
the right-side horizontal metal contact 341.
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CA 02279688 1999-08-OS
Figures 11 through 13 illustrate a hand-held electric sealer according to a
fifth
embodiment of the present invention. This fifth embodiment comprises a safety
switch
100. The safety switch 100 is provided at the front side of the casing 10,
comprising a
knob 101, an electrically insulative stop rod 102, and a shaft 103. The shaft
103 is
mounted in a hole 16 inside the casing 10. The electronically insulative stop
rod 102 is a
substantially V-shaped rod turned about the shaft 103. The knob 101 is fixedly
connected
to a part of the stop rod 102, and extended out of a top notch 17 at the front
side of the
casing 10. Further, a spring cap 151 is covered on a spring 15 inside the
casing 10, and
forced upwards by the spring 15 to support the press bar 20 in the open
position.
Referring to Figures 12 and 13 again, when not in use, the knob 101 is
operated by hand to turn the stop rod 102 about the shaft 103 to a first
position where the
two opposite ends of the stop rod 102 are suspended above the horizontal metal
contacts
331 and 341 to stop the metal locating plates 43 from contacting the
horizontal metal
contacts 331 and 341. On the contrary, when using the hand-held electric
sealer, the stop
rod 102 is turned about the shaft 103 to a second position where the two
opposite ends of
the stop rod 102 are moved away from the horizontal metal contacts 331 and
341, for
enabling the metal locating plates 43 to be lowered with the sealing mechanism
30 into
contact with the horizontal metal contacts 331 and 341. This safety switch 100
can be
used in either of the first, second and third embodiments, or any similar
electric sealer.
Figures 14 through 16 illustrate a sixth embodiment of the present invention.
According to this embodiment, the sealing mechanism is substantially
immovable, i.e., the
sealing mechanism cannot be moved vertically. The hand-held electric sealer of
the sixth
embodiment is energizable by a battery set. According to this sixth
embodiment, the
sealing mechanism 40 includes a heat insulative base 41, a heating wire 42,
two metal
locating plates 43, and a heat resistant cover sheet 14. When assembled, the
sealing
mechanism 40 is disposed above the front contact holder 31, and the metal
locating plates
43 are maintained in contact with the horizontal metal contacts 331 and 341.
The front
cover plate 51 holds the sealing mechanism 40 in place, enabling the metal
locating plates
43 to be maintained in contact with the horizontal metal contacts 331 and 341.
The fifth embodiment further comprises a safety device, which can be a
safety switch 75 or a press-button switch 76. Both the safety switch 75 and
the press-
button switch 76 may be simultaneously installed. in this case, the heating
wire 42 can be
turned on only when the safety switch 75 and the press-button switch 76 are
both
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CA 02279688 1999-08-OS
switched on. Referring to Figures 14 through 16 again, the left-side first
metal contact 33
and the left-side horizontal metal contact 331 are separately installed, and
an electric wire
721 is connected between the left-side first metal contact 33 and the left-
side horizontal
metal contact 331. The safety switch 75 is installed in the electric wire 721
to switch
on/off the circuit. Alternatively, the right-side first metal contact 34 and
the right-side
horizontal metal contact 341 can be separately installed and connected by an
electric wire
731, and the press-button switch'76 can be installed in the electric wire 731
and controlled
to close/open the circuit. If desired, the second metal contacts 35 can be
separated from
each other, and connected by an electric wire in which the safety switch or
press-button
switch can be installed and operated to close/open the circuit. The
application of the safety
switch and/or press-button switch can be used in any of the above embodiments.
Referring to Figure 14 again, the sealing mechanism 40 can have a plurality of
heating wires 42. The cross section of the heating wires) 42 can have a
circular shape,
polygonal shape, or any of a variety of shapes.
When the safety switch 75 is switched on, the two thermoplastic flaps of the
article to be sealed are put in between the heat insulative block 21 of the
press bar 20 and
the projecting block 411 of the heat insulative base 41 of the sealing
mechanism 40, then
the press bar 20 is pressed down, and at the same time the press-button switch
76 is
depressed, causing the heating wires) 42 to produce heat, enabling the two
thermoplastic
flaps of the article to be sealed. When the press-button switch 76 is
released, the heating
wire(s1 42 is (are) off. After use, the safety switch 75 is switched off.
Figure 17 shows a seventh embodiment of the present invention. According
to this embodiment, the sealing mechanism is substantially immovable, and
energizable by
an AC adapter. As illustrated, a front contact holder 31, which holds two
horizonal metal
contacts 331 and 341, and a power socket 70 are mounted in the casing 10. The
power
socket 70 receives external power supply, and has two opposite terminals
respectively
connected to the horizonal metal contacts 331 and 341 by respective electric
wires 72 and
73. The aforesaid safety switch 75 and press-button switch 76 can be
selectively installed
in the electric wire 72 or 73, or connected in series in the electric wire 72
or 73. Two or
more safety switches or press-button switches may be installed. When a
plurality of safety
switches or press-button switches are installed, the sealing mechanism can be
operated only
when all safety switches or press-button switches are switched on. The
installation and
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CA 02279688 1999-08-OS
operating of the switches of the seventh embodiment may be used in the second
embodiment.
Figure 18 illustrates an eighth embodiment of the present invention. The
sealing mechanism according to this eighth embodiment is substantially
immovable, and
energizable by an internal battery set or an external AC adapter. According to
this
embodiment, the casing 10 comprises a battery chamber 30 for holding a battery
set. The
battery chamber 30 comprises a front contact holder 31 transversely disposed
at a front
side, a rear contact holder 32 transversely disposed at a rear side, a pair of
first metal
contacts, namely, the left-side first metal contact 33 and the right-side
first metal contact
34 bilaterally provided at the front contact holder 31, a second metal contact
35 bilaterally
provided at the rear contact holder 32, and two horizontal metal contacts
namely a left-side
horizontal metal contact 331 and a right-side horizontal metal contact 341
respectively
disposed in contact of the first metal contacts 33 and 34. Please see also
Figure 8, an
electric connector 90 is mounted in the casing 10. The electric connector 90
comprises a
first terminal 91, a second terminal 92, and a third terminal 93. The
terminals 91, 92 and
93 are respectively connected to the left-side first metal contact 33, the
left-side horizontal
metal contact 331 and the right-side horizontal metal contact 341 by electric
wires 71, 72
and 73. Before the installation of an AC adapter 80 in the electric connector
90, the first
terminal 91 and the second terminal 92 are electrically connected. When an AC
adapter 80
is connected to the electric connector 90, the second terminal 92 is forced
away from the
first terminal 91, i.e., the battery is off after installation of the AC
adapter 80 in the electric
connector 90. Therefore, only battery power or AC power is exclusively
provided to the
sealing mechanism at any one time. A safety switch and a press-button switch
(not shown)
can be connected in series, and installed in the electric wire 72.
Alternatively, a safety
switch and a press-button switch may be connected in series, and installed in
the position
corresponding to the position of the safety switch 61 of the aforesaid fourth
embodiment.
The operations of the sealing mechanism, the safety switch and the press-
button switch are
similar to the sixth and seventh embodiments.
Referring to Figure 19, the sealing mechanism can be detachable. As
illustrated, the horizontal metal contacts 331 and 341 each have an upright
lug 332 or 342,
which has a locating hole 333 or 343. The metal locating plates 42 of the
sealing
mechanism 40 each have a bolt 431 at an outer side. By inserting the bolts 431
of the
metal local plates 43 into the locating holes 333 and 343 of the metal contact
plates 331
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CA 02279688 1999-08-OS
and 341, the sealing mechanism 40 is coupled between the horizontal metal
contacts 331
and 341. Because the sealing mechanism 40 is detachable, it can be replaced
with a new
one when its heating wire or heat resistant cover sheet is damaged.
Referring to Figures 20 and 21, the sealing mechanism 40 can be installed in
the free end of the press bar 20. As illustrated, the press bar 20 comprises
two metal press
plates 25 respectively connected to the sealing mechanism 40. The casing 10
comprises a
heat insulative block 18 at the top corresponding to the sealing mechanism 40
at the press
bar 20. A switch 19 is installed in the casing 10, and controlled to turn
on/off the sealing
mechanism 40. When the press bar 20 is pressed down to force the sealing
mechanism 40
against the heat insulative block 18, the metal press plates 25 are
simultaneously pressed
on the switch 19, causing the switch 19 to be switched on, and therefore the
electric
circuit is closed, enabling electricity to be transmitted to the sealing
mechanism 40. In
Figures 20 and 21, the sealing mechanism 40 is movably provided at the free
end of the
press bar 20 (the sealing mechanism 40 is coupled to the free end of the press
bar 20 and
supported on a spring memberl. Alternatively, the sealing mechanism 40 can be
fixedly
secured to the free end of the press bar 20.
The design of arranging the sealing mechanism at the press bar can be used in
any of a variety of hand-held electric sealers, including battery-operated
electric sealers, AC
electric sealers. AC/DC dual mode electric sealers.
Referring to Figures 22-26, another embodiment of the present invention
including a detachable heat resistant cover sheet is shown. In this
embodiment, the sealing
mechanism 40 includes a heat insulative base 302, an electric heating wire 42,
a pair of
metal locating plates 43, a heat resistant cover sheet 44, and a frame 304.
The heat
resistant cover sheet 44 is held within the frame 304. The heat insulative
base 302
includes a protrusive portion 306 in the middle, two coupling recessed
portions 308 at two
opposite lateral sides, and opposite bottom edges 310. The metal locating
plates 43 are
fastened to the heat insulative base 302 at two opposite locations. The
electric heating
wire 42 is mounted on the protrusive portion 306 of the heat insulative base
302, and
secured in place by the metal locating plates 43. The frame 304 is mounted
around the
protrusive portion 306 of the heat insulative base 302 to hold down the heat
resistant cover
sheet 44 on the protrusive portion 306 over the electric heating wire 42. The
frame 304
includes a top portion 310 having defined therein an opening 312 and a
plurality of
downwardly extending hooks 314. The frame 304.is secured to the heat
insulative base
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CA 02279688 1999-08-OS
302 by engaging the hooks 314 in the coupling recessed portions 308. It will
be
understood that the frame 304 can be secured to the heat insulating base 302
in a number
of different ways. For example, threaded fasteners or snaps can be provided,
the frame
may be threaded, the frame may be hinged to the housing, the frame may be
integral with
the housing. Any method of securing the frame 304 to the heat insulating base
is within
the scope of the present invention.
The heat resistant cover sheet 44 and the frame 304 can be fastened
together by directly molding the frame 304 on the heat resistant cover sheet
44 or by
adhering the heat resistant cover sheet 44 to the frame 304 using an adhesive.
The frame
304 is preferably comprised of a plastic, and can be directly molded on the
heat resistant
cover sheet 44 by injection molding.
The electric heating wire 42 can vary in thickness. Preferably, the thickness
of the electric heating wire varies within the range of 0.10 mm to 0.50 mm.
However, it
will be understood that the electric heating wire 42 of the present invention
can be any
thickness.
Referring to Figure 23, when replacing the heat resistant cover sheet, the
downwardly extending hooks 314 of the frame 304 are disengaged from the heat
insulative
base 302. The used heat resistant cover sheet 44 is then removed from the
frame 304 and
replaced with anew heat resistant cover sheet 44. The frame 304 is then
fastened to the
heat insulative base 302 to secure the new heat resistant cover sheet 44 to
the protrusive
portion 306 of the heat insulative base 302 and at least partially over the
electric heating
wire 42. Alternatively, when frame 304 is molded or adhered to cover sheet 44,
thus
forming a single unit, the entire unit can be removed and replaced with a new
frame 304
and cover sheet 44.
Referring to Figures 24 to 26, alternative embodiments of the heat insulative
base 302 as well as the frame 304 are also included within the scope of the
present
invention. In Figure 24, the heat insulative base 302 has two symmetrical
pairs of coupling
recessed portions 316 at two opposite sides for engagement with the downwardly
extending hooks 314 of the frame 304. The heat resistant cover sheet 44 can be
a meshed
sheet member made from a heat resistant material, such as TEFLON~
(polytetrafluoroethylene) or the like, that provides a smooth surface and
protects the electric
heating wire 42. In a preferred embodiment, the heat resistant cover sheet 44
is in the
range of 5.0 mm to 9.0 mm wide and 8.0 mm to 12.0 mm long. However, it will be
tnnocsusiasse ~ _ 13 _
r
CA 02279688 1999-08-OS
understood that the size of the heat resistant cover sheet 44 is not a
limitation. Any width
and length of the heat resistant cover sheet 44 are within the scope of the
present
invention.
Alternatively, the heat resistant cover sheet 44 can have an adhesive thereon
for adhering the heat resistant cover sheet 44 to the electric heating wire 42
and the
protrusive portion 306 of the heat insulative base 302. The adhesive can be a
special
adhesive that will not damage the electric heating wire 42 when the heat
resistant cover
sheet 44 is removed, thereby allowing the heat resistant cover sheet 44 to be
temporary
and replaceable.
In Figure 25, the heat insulative base 302 includes two horizontal coupling
grooves 318 at two opposite lateral sides. The frame 304 has two coupling
flanges 320 for
engaging the horizontal coupling grooves 318 of the heat insulative base 302.
In Figure 26, the frame 304 has a plurality of downwardly extending hooks
322 respectively hookad in the peripheral edge of an opening 324 on the front
cover plate
51.
As shown in Figure 27, a plurality of electric heating wires 44 can be
employed. The electric heating wires 44 are mounted on the protrusive portion
304 of the
heat insulative base 302, and secured in place by the metal locating plates
43. Any
number of electric heating wires 44 is within the scope of the invention.
It is to be understood that the drawings are designed for purposes of
illustration only, and are not intended as a definition of the limits and
scope of the invention
disclosed.
~.nnocs~zsmsa i _ 14 _
