BACKGROUND OF THE INVENTION
I. FIELD OF THE INVENTION
[0001] The present invention relates generally to automatic switching apparatus and, more
particularly, to automatic switching apparatus for use with appliances having electronic
controls.
II. DESCRIPTION OF THE PRIOR ART
[0002] The possibility of leaving an electrically operated appliance, such as a pressing
iron, turned on and unattended for an extended period of time is a concern to many
users. Some top-of-the-line pressing irons now provide the feature of automatic shut-off
if the iron is not used for a predetermined period of time. Typically, the feature
is included in a complete electronic control system using a microprocessor and an
electromagnetic relay or a solid state switch such as a triac to control power to
the heating element. Both of these devices are expensive and have other drawbacks
as well. A triac, for example, requires a sizeable heat sink to dissipate its power
loss when the iron is on and an iron is obviously a poor location for such a device
because of the hot environment it represents. A power relay requires a significant
amount of power to operate and tends to heat up when it is kept energized in the hot
iron environment.
SUMMARY OF THE INVENTION
[0003] It is an object of the present invention to provide an improved automatic switching
apparatus, and an improved electric iron incorporating such.
[0004] According to one aspect of the present invention, there is provided an automatic
switching apparatus for a hand-held electrically operated appliance, characterized
by switch means convertible between a power mode for electrically connecting the appliance
to source of electrical power and a dormant mode for electrically disconnecting the
appliance from the source of electrical power; electromechanical means operable when
energized for converting said switch means to the dormant mode; a motion sensor responsive
to movement of the appliance for generating a signal; and timer means for timing a
preset period of time responsive to said motion sensor signal, and for energizing
said electromechanical means upon lapse of said preset period of time unless a subsequent
motion sensor signal is generated.
[0005] Manually operable reset means may be provided for converting the switch means to
the power mode. The reset means may comprise latch means for latching the switch means
in the power mode.
[0006] The switch means may comprise first and second mutually engageable contacts. A resilient
blade may bias the second contact away from engagement with the first contact. The
latch means preferably releasably engages with the blade for holding the first and
second contacts mutually engaged, the reset means, when actuated, effecting engagement
of the latch means with said blade.
[0007] Electronic circuitry means which includes the timer means, may be provided for limiting
the energizing of the electromechanical means to a period of up to about one second
in time upon energization of the electromechanical means by the timer means.
[0008] The above automatic switching apparatus is preferably included in an electric pressing
iron.
[0009] The electric iron may have a sole plate and a heating element for heating the sole
plate, the above switch means connecting the heating element to the source of electrical
power in the power mode and disconnecting the heating element from the source of electrical
power in the dormant mode.
[0010] A housing of the iron above the sole plate may contain the switch means, the electromechanical
means, the motion sensor and the timer means. A manually depressible button may be
resiliently urged outwardly with respect to the housing, actuation of this button
resetting the switch means from the dormant mode to the power mode.
[0011] The housing of the iron preferably has a handle portion containing a printed circuit
board, the circuit board having mounted thereon and switch means, the electromechanical
means, the motion sensor and the timer means.
[0012] A lamp may be disposed under the reset button and be electrically connected to the
switch means for indicating when the electric iron is in the power mode.
[0013] Another object of the present invention is to provide an improved method of operating
a hand-held appliance, such as an electric iron.
[0014] Accordingly, there is provided by another aspect of the present invention a method
of operating a hand-held electrically operated appliance having an automatic switching
apparatus characterized by the steps of connecting the appliance to a source of electrical
power for operation of the appliance; sensing the lack of motion of the appliance;
timing electronically the length of time that the appliance remains motionless; and
disconnecting the appliance from the source of electrical power when the length of
time that the appliance remains motionless exceeds a preset value.
[0015] It will be appreciated that the present invention, as disclosed in relation to the
preferred embodiments, represents a simpler and lower cost system according to which
power may be controlled by a manually closed set of contacts which may be tripped
open by a small solenoid. The solenoid is preferably energized by an electronic timing
circuit whenever the iron is "on" but not moved for a predetermined time interval,
typically, seven to ten minutes. A small mercury switch may be mounted so that it
opens and closes randomly when moved by the normal ironing motions. Each time the
switch opens, the timer is reset to the start of its main cycle so that with normal
iron use, the power will never be turned off.
[0016] As the cost of electronic circuitry continues to decrease, it has become possible
to provide features for home appliances which were not heretofore economically feasible.
Such features include those directed to operating convenience and increased utility
as well as features which provide for safer operation of the appliance. The preferred
embodiments incorporate some such features together with a simplified mechanism enabling
the user to reactivate the appliance once it has been turned off for lack of use.
[0017] One feature of the preferred embodiments of the present invention is that no energy
need be expended in a separate system to keep the iron energized. That is, unlike
some known constructions, which require the continuous application of electricity
for operating relays and the like to open and close contacts, and resulting in the
further generation of non-usable heat, the preferred embodiments of the invention
rely on operator energy to actuate a button to return the iron to the power mode.
Furthermore, only a momentary flow of electricity is required to convert the iron
to the dormant mode in the event the iron remains inactive for the seven to ten minute
time interval mentioned above.
[0018] Other objects, features and advantages of the present invention will become more
fully apparent from the following detailed description of the preferred embodiments,
the appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
Figure 1 is a top plan view, certain parts being cut away, illustrating an electrical
appliance in the form of a pressing iron embodying the invention;
Figure 2 is a side elevation view, certain parts being cut away and in section, of
the pressing iron illustrated in Figure 1;
Figure 3 is a detail elevation cross section view illustrating a portion of the appliance
depicted in Figures 1 & 2;
Figures 4 & 5 are further detail views in cross section, similar to Figure 3, and
illustrating successive positions of a reset mechanism utilized by the invention;
Figure 6 is a top plan view of a circuit board utilized by the invention and illustrating
the relative positioning of the electronic components thereon;
Figure 7 is a schematic drawing of a typical electronic circuit utilized by the invention;
Figure 8 is a detail elevation cross section view similar to Figure 3 and depicting
another embodiment of the invention;
Figure 9 is a detail bottom plan view of the embodiment depicted in Figure 8;
Figure 10 is a detail front elevation view of parts illustrated in Figure 8; and
Figure 11 is a detail side elevation view of the construction illustrated in Figure
10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Turn now to the drawings and initially to Figures 1 & 2 which illustrate an electric
pressing iron 20 which includes a sole plate 22, typically of cast aluminum, on which
is mounted a housing 24, typically of molded plastic. The housing 24 includes a bottom
portion or skirt 26 and a handle portion 28 connected by a rear pedestal 30 and a
throat 32. Extending from the rear of the handle portion 28 and the top of the pedestal
30 is a line cord 34 for connecting the iron to a source of power. A number of user
controls including a temperature selector knob, steam actuator, and steam control
button may be provided on the housing 24 but constitute no part of the present invention
and thus will not be discussed.
[0021] Turn now to Figure 3 which illustrates at the left side, that is, the front of the
handle portion 28, a pair of mechanisms, namely a solenoid mechanism 36 and a reset
mechanism 38. These mechanisms are mounted on the front end of the printed circuit
board 40 upon which is also mounted an electronic timing circuit 42 including an electronic
timer U₁ and a motion detector switch MS. The specifics of the electronic timing circuit
will be described below. A pair of contacts 46 & 48 are connected in series with one
power line extending between the line cord 34 (Figure 2) and all of the electrical
or electronic circuits in the iron 20. The contact 46 is mounted to a fixed blade
50 which is riveted or otherwise secured to the circuit board 40. The contact 48 mounted
on a flexible blade 52 which is biased such that, unless otherwise restrained, the
contacts will be moved to an open position as illustrated in Fig. 4.
[0022] A latch 54 serves to hold the contacts closed, the upward force exerted by a compression
spring 56 accomplishing this result. Specifically, the latch 54 comprises a downwardly
extending leg 58 (Figure 5) terminating at a foot 60 which is engageable with the
undersurface of the flexible blade 52. The latch 54 also includes a generally horizontally
extending head member 62 which intersects with the leg 58 at an upwardly projecting
pivot bearing 64 (Figure 3). The pivot bearing 64 is received in a groove 66 formed
in an underside of the reset button 68. The compression spring 56 extends between
a spring support platform 70, cantilevered from the support structure for the solenoid
mechanism 36, and the head member 62.
[0023] The solenoid mechanism 36 comprises a housing or frame 72 suitably mounted on the
printed circuit board 40. The housing 72 encompasses a coil 74 which, when energized,
drives an armature 76 to the left as seen in Figure 3. A free floating rod 78 is mounted
for reciprocation in a bushing 80 supported on the housing 72 and is coaxial with
the armature 76. When the coil 74 is energized, the armature 76 moves to the left,
pushing the leg 58 of the latch 54 also to the left (Figure 4). In this manner, the
foot 60 moves out from under the flexible blade 52, thus allowing the contacts 46
and 48 to open. The contacts are then held open by the flexible blade 52. When the
solenoid is de-energized, the foot 60 is held against the nose 82 by the bias of the
compression spring 56 acting on the latch 54.
[0024] To reenergize the iron, the reset button 68 is depressed as indicated by an arrow
83 in Figure 5,to a position somewhat below the position illustrated in Figures 3
& 4. The latch 54, and specifically the foot 60, slides down the front portion of
the nose 82 and is drawn under the extreme end of the flexible blade 52 by the spring
56 acting on the head member 62.
[0025] At this stage of operation, the coil 74 is not energized which leaves the armature
76 and rod 78 free to move axially in a direction away from the latch 54. As illustrated
in Figure 5, the leg 58, in returning to its latched position, pushes the rod 78 and
therefore the armature 76 towards the right. When the user releases the button 68,
the spring 56 raises the button, and with it the latch 54, until the contacts 46 and
48 again close to the position illustrated in Figure 3, thereby again energizing the
iron.
[0026] It is noteworthy that in this embodiment the contacts 46 and 48 cannot be held closed
by holding the button 68 down. This is for the reason that depressing the button allows
the contacts to open. Even if the button is jammed in its normal position, the switch
will still trip open when the coil is energized.
[0027] Turn now to Figures 3, 6 and 7. The electronic control circuitry is physically illustrated
in Figure 6 and is schematically illustrated in Figure 7. Power is controlled by the
manually closed set of contacts 46 and 48 which, as just described, can be tripped
open by the small solenoid mechanism 36. The coil 74 of the solenoid mechanism is
energized by the electronic timing circuit 42 (Figure 7) whenever the iron is "on"
but not moved for a predetermined time interval. This time interval is typically seven
to ten minutes, but can be of any desired duration. A small motion detector switch
MS, which may be a mercury switch, is mounted on the circuit board 40 such that it
opens and closes randomly when moved by normal ironing motions. Each time the switch
opens, the electronic timer U₁, is reset to the start of its timing cycle so that
with normal iron use the power will never be turned off.
[0028] Referring now particularly to Figure 7, a power lead W₁ is connected to the reset
switch represented by the contacts 46 and 48 (see Figure 3-5), a single pole switch
which is closed to a latch closed condition, as previously described, by manually
depressing the reset button 68. This reset switch then remains closed until tripped
open by the solenoid coil 74 being energized, also as previously described. From the
reset switch represented by the contacts 46 and 48, power proceeds through a power
lead W₂ to an over temperature limiter 84, a thermostat 86, and a calrod heating element
88 which are all the same as in conventional irons. The other calrod terminal is connected
to a power lead W₃ and is also the "common" circuit for the electronic circuitry.
A capacitor C₅ and a metal oxide varistor M, one example being a General Electric
V130LA2 MOV, are added across the power leads W₂ and W₃ for transient suppression.
[0029] Whenever the contacts 46 and 48 are closed, the user is informed that the iron is
"on" by the illumination of a neon bulb N, current flow through which is limited by
a resistor R₁₂ in series therewith. With the contacts 46 and 48 closed, power is also
supplied to the electronic circuitry. The resistors R₁ and R₁₁, diode CR₁ and capacitor
C₁ form a d.c. power supply providing approximately +11 volts across the capacitor
C₁. This voltage is reduced and regulated at 9.1 volts by the resistor R₁₀ and the
zener diode CR₃. An integrated circuit timer U₁ is used to time the seven to ten minute
turn off delay. An acceptable form of the circuit timer U₁ is a TLC555C integrated
circuit timer manufactured and sold by Texas Instruments, or equivalent. The capacitor
C₃ is continually being charged through the resistor R₄, and since no base current
is supplied to the transistor Q₁, the transistor Q₁ is "off" and does not discharge
the capacitor C₃. The seven to ten minute interval is determined by the time required
to charge the capacitor C₃ to two-thirds the voltage at pins 4 and 8 of the timer
U₁.
[0030] The motion detector switch MS, a small mercury switch, as noted above, is normally
closed and capacitor C₂ is charged to approximately 4.5 volts. An acceptable version
of the motion detector switch suitable for purposes of the invention is model TS66
sold by Fifth Dimension, Inc. of Clinton, New Jersey. When the iron 20 is moved, as
in normal ironing motion, the motion switch MS opens momentarily and capacitor C₂
starts to charge towards approximately 9 volts through the resistor R₂. This charge
current is also base to emitter current in transistor Q₁ so that the transistor Q₁
is turned on, momentarily, thereby discharging capacitor C₃ and thus resetting the
timer U₁. When the motion switch MS recloses, capacitor C₂ is partially discharged
again through the resistor R₃, the motion switch MS, and resistor R₉, and the transistor
Q₁ is again turned "off".
[0031] The timer U₁ is connected as a astable oscillator having its output at pin 3 "high"
(approximately 9 volts) for seven to ten minutes followed by several milliseconds
"low" (approximately 0.1 volts) depending upon C₃/R₅ discharge timing. Resistor R₅
determines the rate at which capacitor C₃ is discharged when the circuit times out
because the iron has not been used for 7 to 10 minutes. This insures that the SCR
will be turned on long enough to always trip the solenoid actuated switch. The transistor
Q₂ inverts this voltage from pin 3 of the time U₁ so that its collector is at a low
voltage when pin 3 is high and high when pin 3 goes low at the end of the timing period.
In this context, resistor R₆ is the biasing resistor for transistor Q₂ when pin 3
is high thereby limiting the base current of transistor Q₂ to a safe value. When the
collector of the transistor Q₂ goes "high", the diode CR₂ conducts enough current
through resistor R₇ to resistor R₈ and to the gate of an SCR Q₃ to cause the SCR gate
to turn "on" during positive half cycles of voltage on the power lead W₁. Resistor
R₇ biases the gate of SCR Q₃ and limits the collector current to transistor Q₂ to
a value that enables the charge on capacitor C₁ to last long enough to insure that
the solenoid 36 will trip the switch. Heavy current pulses then flow through the solenoid
coil 74 causing it to trip the reset switch contacts 46 and 48 to an open position
which removes power from the iron heating circuit and from the control circuit.
[0032] Capacitors C₄ and C₆ increase the noise immunity of the timer U₁ as is well known.
Also, a resistor R₈ stabilizes the gate of SCR Q₃ so that voltage withstand and dv/dt
characteristics are improved.
[0033] Thus it will be appreciated that the mechanism described is a simple, low cost, low
power, manually closed but electrically tripped open switching device which is ideally
suited for electrical appliances such as a pressing iron. The energy to close and
open the electrical contacts and the contact holding force and weld breaking force
are all supplied by the user in pushing the reset button 68. Only a momentary current
is used to trigger the device and allow a previously stressed spring, namely the flexible
blade 52, to open the power switching contacts 46 & 48.
[0034] Another, and preferred, embodiment of the mechanism of the invention will now be
described with reference to Figures 6-11. The circuit board 40 supporting all of the
electronic components previously described is suitably mounted in the handle portion
28 of the iron 20. As seen in Figure 8, a solenoid mechanism 102 is mounted on the
circuit board 40 and includes a plastic chassis or coil bobbin 104, a coil 106, and
an armature 108 which moves to the left (Figure 8) when the coil 106 is energized.
[0035] Just inboard from an end 110 of the circuit board 40 is an opening 112 (Figure 9)
through which a stationery contact 114 extends, mounted on a suitable support 116
which is suitably fixed to the circuit board. A flexible blade 118 is bifurcated at
a forward end and has a pair of tabs 119 at a rearward end received through openings
119A and in the circuit board (Figure 9). The tabs 119 are bent over and engage the
circuit board to affix the blade thereto. The blade 118 extends forwardly and has
mounted thereon a movable contact 120 which is engageable with the stationery contact
114. However, the flexible blade 118 is formed of a suitable spring material biased
so that the contacts 114 and 120 are normally separated unless forced together by
an outside influence.
[0036] Such an outside influence is in the form of a latch 122. The latch 122 includes an
elongated latch release spring 124 mounted at its rear end to the bobbin 104 of the
solenoid mechanism 102 and biased upwardly. Near its forwardmost end, the latch release
spring 124 has a pair of depending wings 126 which are suitably pierced to receive
a transversely extending bearing pin 128 for pivotally mounting thereon a downwardly
extending latch lever 130. At a lower extremity of the latch lever 130 is a foot 132
which is releasably engageable with an edge 134 in a recessed region 136 at the end
110 of the circuit board 40. A latch spring 133 is also mounted on the pin 128, with
one end bearing against the latch release spring 124 and the other end against the
latch lever 130 to urge the latter in a counterclockwise direction (Figures 8 and
11). Spaced above the foot 132 and integral with the latch lever is a lobe 138 which
is engageable with an upper surface of the flexible blade 118. A non-magnetic extension
140, preferably of molded plastic material, at the forward end of the armature 108
is engageable with a rear surface of the latch lever 130 and is selectively operable
to move the foot 132 out of engagement with the edge 134.
[0037] A reset button 142 extends through an opening 144 in the handle portion 28. A peripheral
flange 146 on the button 142 is engageable with the opening 144 and restrains the
button against further upward travel. Since the reset button 142 is mounted on the
upper surface of a button retainer spring 148, it is, in effect, captured in place
on the handle portion 28. The retainer spring 148 is suitably fastened to the handle
portion 28 far to the rear of the reset button 142,and at its forward end, the button
142 is provided with a hammer 150 which is engageable with an upper surface of the
latch release spring 124.
[0038] The neon lamp N is illustrated as being suitably mounted on a support 152 fixed to
the bobbin 104 or other structure within the handle portion 28. The reset button is
fabricated from a translucent material and the neon lamp N is positioned beneath the
reset button so as to create a glow in the surface of the reset button when the lamp
is turned on.
[0039] As previously explained, after the iron 20 has remained motionless for the predetermined
period of time, for example, 7 to 10 minutes, as previously described, a pulse of
electrical energy is directed via the electronic circuit to the coil 106. The pulse
is only momentary, no greater than one second in duration, and typically less than
50 milliseconds in duration. When the coil is thereby energized, the armature 108
is magnetically moved forward (to the left in Figure 8) toward the center of the coil
106 where the magnetic lines of force are concentrated and the strongest.
[0040] The non-magnetic molded extension 140 thereby engages the latch lever 130 pushing
it forward against the bias of the latch spring 133 to unlatch the foot 132 from the
front edge 134 of the printed circuit board 40. The force of the upward biased latch
release spring 124 moves the latch lever 130 upwardly and with it the latch spring
133. Motion is also aided by the upward bias of the flexible blade 118 which moves
upward upon release of the foot 132 and opens the switch contacts 114 and 120 to turn
off power to the iron.
[0041] To restore power to the iron, the user pushes the reset button 142. With the downward
motion of the reset button, the latch lever 130 is moved downwardly and with the rearward
bias of the latch spring 133, the foot 132 engages the edge 134 of the printed circuit
board 40. A cam surface 154 on the foot 132 slides along the edge 134 until a shoulder
156 is reached which allows the latch lever to pivot rearwardly (counterclockwise
in Figure 11) such that the shoulder 156 firmly engages the undersurface of the printed
circuit board. Thus, once again, the contacts 114 and 120 are closed to restore power
to the iron. The contacts remain closed until the coil is again energized. The neon
lamp N, being connected in parallel with the control and power circuits, is lighted
when the contacts 114 and 120 are engaged. In an opposite fashion, when the contacts
114 and 120 are open, the neon lamp is turned off.
[0042] While a preferred embodiment of the invention has been disclosed in detail with specific
values recited for certain of the electronic components for greater understanding,
it should be understood by those skilled in the art that various modifications may
be made to the illustrated embodiment without departing from the scope of the invention
as described in the specification and defined in the appended claims.
1. Automatic switching apparatus for a hand held electrically operated appliance (20),
characterized by:
switch means (46, 48) convertible between a power mode (Fig. 3) for electrically connecting
the appliance to source of electrical power and a dormant mode (Fig. 4) for electrically
disconnecting the appliance from the source of material power;
electromechanical means (74, 76, 78) operable when energized for converting said switch
means (46, 48) to the dormant mode;
a motion sensor (MS) responsive to movement of the appliance (20) for generating a
signal; and
timer means (42) for timing a preset period of time responsive to said motion sensor
signal, and for energizing said electromechanical means (74, 76, 78) upon lapse of
said preset period of time unless a subsequent motion sensor signal is generated.
2. The automatic switching apparatus of Claim 1, characterized in that said timer
means (42) is responsive to the latest in a series of signals from said motion sensor
(MS) for re-initiating a timing sequence of said timer means (42) upon movement of
the appliance (20) before completion of said preset period of time, said timer means
(42) energizing said electromechanical means (74, 76, 78) upon uninterrupted completion
of said preset period of time without movement of said appliance (20).
3. The automatic switching apparatus of Claim 1 or 2, characterized by reset means
(38, 54), manually operable, for converting said switch means (46, 48) to the power
mode.
4. The automatic switching apparatus of Claim 3, characterized in that said reset
means (38, 54) comprises latch means (54) for latching said switch means (46, 48)
in the power mode.
5. The automatic switching apparatus of Claim 4, characterized in that:
said switch means (46, 48) comprises first (46) and second (48) mutually engageable
contacts, and a resilient blade (52) biasing said second contact (48) away from engagement
with said first contact (46);
said latch means (54) releasably engages with said blade (52) for holding said first
and second contacts (46, 48) mutually engaged; and
said reset means, when actuated, effects engagement of said latch means with said
blade.
6. The automatic switching apparatus of Claim 4 or 5, characterized in that said electromechanical
means (74, 76, 78) comprises an electromagnetically driven armature (76) movable towards
the away from said latch means (54), said armature when driven towards said latch
means (54) releasing said latch means (54) to place said switch means (46, 48) in
the dormant mode.
7. The automatic switching apparatus of Claim 6, characterized in that said armature
(76) comprises a plunger (76) of a solenoid (36), said plunger moving a free floating
rod (78) aligned therewith, said rod engaging said latch means (54) when said solenoid
(36) is energized.
8. The automatic switching apparatus of any preceding claim, characterized by electronic
circuitry means (40), which includes said timer means (42), for limiting said energizing
of said electromechanical means (74, 76, 78) to a period of up to about one second
in time upon energization of said electromechanical means (74, 76, 78) by said timer
means (42).
9. An electric pressing iron, characterized in that it includes the automatic switching
apparatus of any one of Claims 1 to 8.
10. The electric pressing iron of Claim 9, characterized by a sole plate (22) and
a heating element (88) for heating said sole plate (22), said switch means (46, 48)
connecting said heating element (88) to said source of electrical power in said power
mode and disconnecting said heating element (88) from said source of electrical power
in said dormant mode.
11. The electric pressing iron of Claim 10, characterized by a housing (24) above
said sole plate (22) and containing said switch means (46, 48), said electromechanical
means (74, 76, 78), said motion sensor (MS) and said timer means (42); and by a manually
depressible button (68; 142) resiliently urged outwardly with respect to said housing
(24), actuation of said button (68; 142) resetting said switch means (46, 48) from
said dormant mode to said power mode.
12. The electric pressing iron of Claim 11 when dependent directly or indirectly
on Claim 5, characterized in that:
a latch member (54) extends downwardly from said button (68) and has a foot (60) at
a lower end, in said power mode said foot (60) engaging under said blade (52) and
being urged resiliently upwards to hold said second contact (48) in engagement with
said first contact (46); and
said latch member (54) is moved by said electromechanical means (74, 76, 78), when
energized, to disengage said foot (60) from said blade (52) and allow said blade (52)
to bias said second contact (48) away from said first contact (46) and effect said
dormant mode.
13. The electric pressing iron of Claim 11 when dependent directly or indirectly
on Claim 5, characterized in that:
a latch lever (130) extends downwardly from and is pivotally attached to an elongate
latch release spring (124), said spring (124) extending under and being contactable
by said button (142);
said latch lever (130) having a foot (132) engageable with a fixed member (40), and
having a lobe (138) engageable with said blade (118);
a latching spring (133) biasing said latch lever (130) to pivot relative to said latch
release spring (124);
said button (142) upon actuation moving and stressing said latch release spring (124)
to allow said latching spring (133) to effect engagement of said foot (132) under
said fixed member (40) and to effect engagement of said lobe (138) with said blade
(118) to move said second contact (120) into engagement with said first contact (114)
and effect said power mode; and
said latch lever (130) being pivoted by said electromechanical means (74, 76, 78),
when energized, to disengage said foot (132) from said fixed member (40) and enable
said latch release spring (124) to move said latch lever (130) upwardly and effect
said dormant mode.
14. The electric pressing iron of Claim 10, 11, 12 or 13, characterized by said iron
(20) having a handle portion (28) containing a printed circuit board (40), said circuit
board (40) having mounted thereon said switch means (46, 48), said electromechanical
means (74, 76, 78), said motion sensor (MS) and said timer means (42).
15. The electric pressing iron of Claim 11, 12 or 13, characterized by a lamp (N)
disposed under said button (68, 142) and electrically connected to said switch means
(46, 48) for indicating when said electric iron (20) is in the power mode.
16. A method of operating a hand-held electrically operated appliance having an automatic
switching apparatus as claimed in any one of Claims 1 to 8, characterized by the
steps of:
connecting the appliance to a source of electrical power for operation of the appliance;
sensing the lack of motion of the appliance;
timing electronically the length of time that the appliance remains motionless; and
disconnecting the appliance from the source of electrical power when the length of
time that the appliance remains motionless exceeds a preset value.