Note: Descriptions are shown in the official language in which they were submitted.
37~
.,a.ll.~Q~ Wl.~.~HlNG .a.~ US .EQB ~N EI~E5
~I.IAN~
~Q~ ~2E ~ INVE
I. ~ ~E ~ INVEN~ION
The presen'c invention relates generally to automatic
switching apparatus and, rl~ore particularly, to
10 automatic switching apparatus for use with appliances
having electronic controls.
II. DESG~IPTIQ~ QE THE PRIQ~ A~
The possibility of leaving an electrically operated
appliance, ~uch as a pressing iron, turned on and
unattended for an extended period of ti~e i8 a concern
to ~any user~. So~e top-o~-the-line pressing irons
now provide the feature o~ auto~atic shut-off if ,the
iron is not used for a predetermined period of ti~e.
l'ypically, the feature is included in a co~plete
electronic control syste~ using a microprocessor and an
electro~agnetic relay or a solid state switch such as a
triac to control power to the heating ele~ent. Both of
these devices are expensive and have other drawback~ as
well. A triac, for example, requires a sizeable heat
sink to dissipate its power loss when the iFOn is on
and an iron is obviously a poor location for such a
device because of the hot enviromnent it represents. A
30 power relay requires a significant amount of power to
37
--2--
operate and tends ko heat up when it is kept energized
in the hot iron enviroml~ent.
RY QE T~ ~
It was with knowledge of the ~rior art and the problems
5 existing which gave rise to the present invention. In
brief~ the present invention is directed towards an
automatic switching apparatu or a hand held
el ectrical ly operated appl iance such as a pressing
iron, A motion sensor and an electronic ti~er
lo cooperate to auto~atically shut of~ the iron i the
iron remains stationary for a predetermined period of
time. A simplified ~echanism is manual ly operabl e in
the event the user desires to reactivate the iron. A
circuit board ~ounting simplified electronic circuitry
is located within the handle of the iron, An
appropriate indicator informs the user whether the iron
is in the active ~ode or inactive mode.
~2~
The present invention, as disclosed, represents a
simpler and lower C08t syste~ according to which power
is control led by a manual ly closed set of contact
which can be tripped open by a ~n~all ~olenoid. The
S solenoid is energized by an electronis tin~ing circuit
whenevec the i ron is "on" but not moved ~Eor a
predetern~ined time interval, typically, seven to ten
minute~. A s~all mercury switch is n~Qunted so that lt
o~ens and closes rarldomly when Tl~oved by the nor~al
10 ironing ~otions. Each time the switch opens, the tin~er
is rese~ to the s'cart of i~s rt~ain cycle so that with
normal iron use, the power will never be turned off.
As the cost of electronic ci~cuitry continues to
decrease, it has beco~e desirable to provide features
for no~e appliances which were not heretofore
econo~ically feasible. Sucb features include those
directed to operating convenience and incre~sed utility
as well as features which provide ~or safer operation
of the appliance. The present invention incorporates
such features together with a si~plified ~echanis~
enabling the user to reactivate the appliance once it
nas been turned off for lack of use.
One feature of the present invention is that no energy
is expended in a separate system to keep the iron
energized. That is, unl ike son~e known constructions,
wnicn require the continuous application of electricity
for operating relays and the like to open and close
contacts, and resulting in the further generation of
~2~
non-usable heat, the invention relie on operator
energy to actuate a button to return the iron to the
power ~ode. Furthermoret only a momentary ~low of
electricity is required to convert the iron to the
dor~ant mode in the event the iron remains inactive for
the seven ~o ten ~inute time interval ~entioned above.
O~her and further features, objects, advantages, and
benefits of the invention will beco~e apparent fro~ the
L0 following description taken in conjunction with.the
following drawings. It is to be understood that both
the foregoing general description and the following
de~ailed description are exemplary and explanatory but
not restrictive o~ the invention The acco~panying
drawings, which are incorporated in, and constitute a
part of thi~ invention~ illustrate some of the
embodi~ents of the invention and, together with the
description, serve to explain the principles of the
invention in general ter~s.
. 20
BRIEF DESCRIPTIO~ Q.E ~ D~W;L~
Figure 1 is a top plan view, certain parts being cut
away, illustrating an electrical appliance in the for~
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;
~ 37~
Figure 3 i6 a detail elevation cross section view
illustrating a portion of the appliance depicted in
~igures 1 ~ 2;
Figures 4 ~ 5 are further detail view~ in cross
section, si~ilar to Figure 3r and illustratin~
successive positions of a reset ~echanis~ 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 co~ponents ~hereon;
Figure 7 is a schematic drawing of a typical electronic
lS circuit utilized by the invention;
Figure 8 is a detail elevation cross section view
si~ilar to Figure 3 and depicting another e~bodiment of
the invention;
Figure9 is a detail botto~ pl an v iew of the e~bodi~ent
depic~ed 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 Figur 10.
~ z~9~
~E~LE~y QE THE ~E~ EMBQD~ NT~
Turn now to the drawings and initially to Figures 1 & 2
which illustrate an electric pressing iron 20 which
5 includes a sole plate 2~, typically o~ cast alun~inu~,
on which is ~ounted a housing 24, typically o~ n~olded
plastic. The nousing 24 includes a bottom portion or
skirt 26 and a handle portion 28 cor~nected by a rear
pedestal 30 and a throat 32. Extending froJn the rear
10 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
te~perature selector knob, steam actuator; and stea~
control button may be prov ided on the housing 24 but
lS constitute no part of the present invention and thus
wil 1 not be discussed.
Turn now to Figure 3 which illustra~es at the left
side, that is, the front o the handle portion 28, a
pair of ~echanis~s, na~ely a solenoid mechanis~ 36 and
a reset mechanis~ 38. These ~echanis~s are ~ounted on
the flont end of the printed circuit board 40 upon
wnich is also ~ounted an electronic timing circuit 42
including an electronic ti~er Ul and a motion detector
switch MS. The specifics of the electronic ti~ing
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 ~ounted to a fixed blade 50
~2~3
--7~
which i~ riveted or otherwise secured to the circui'c
board 40. The contact 4B mounted on a flexible blade
52 which is biased such that, unl ess otherwise
restrained, the contacts wil 1 be ~oved to an open
5 position as illustrated in Fig. 4~
A latch 54 serves to hold .the contacts closed, the
upward force exerted by a compres~ion ~pring 56
acco~plisning this result. Specifically, ~he latch 54
10 comprises a downwardly extendin~ 1 eg 58 (Figure 5)
ter~inating at a ~oot 60 which i5 engageable with the
undersurface of the flexible blade 52, The latch 54
also includes a generally horizontally extending head
~e~ber 62 which intersects with ~he leg 58 at an
upwardly projecting pivot bearing 64 (Figure 3). The
pivot bearing 64 is received in a groove 66 Por~ed in
an underside of the reset button 68. The co~pression
spring 56 extends between a spring support platfor~ 70
cantilevered from the support structure for the
solenoid ~echanis~ 36 and the head ~e~ber 6~.
The solenoid mechanis~ 36 co~prises a housing or Pra~e
72 suitably ~ounted on the printed circuit board 40~
The housing 72 enco~passes a coil 74 which~ when
energized, drives an ar~ature76 to the leftas seen in
Figure 3. A free floatin~ rod 7~ is ~ounted for
reciprocation in a bushing 80 supported on the housing
72 and is coaxial with the ar~ature 76. When the coil
74 is energized, the ar~ature 76 ~oves to the left,
pushing the le9 58 of the latch 54 also to the left
(Figure ~). In this ~anner~ the foot 60 moves out
from under the ~lexible blade 52, thus allowing the
contac~s 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 bia.s of the compression spring 56 acting on the
latch 54. t
To reenergize the iron, the reset button 68 i~
depressed as indicated by an arrow 83 in Figure 5 to a
position so~ewhat 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 Elexible blade 52 by
the spring 56 acting on the head ~e~ber 62.
At this stage o~ operation, the coil 74 is not
energized which leaves the ar~ature 76 and rod 78 free
to ~ove axially in a direction away fro~ the latch 54~
As illustrated in Figure5, the leg 58, in returning to
its latched position, pushes the rod 78 and therefore
the ar~ature 76 toward 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
~5 and 48 again close to the position illustrated in
Figure 3, thereby again energizing the iron.
It is notewor~hy ~hat in this e~bodiment the contacts
46 and ~8 cannot be held closed by holding tbe button
68 down~ This is for the reason that depressing the
~z~
button allows the contact~ to open. Even if the button
is jan~ed in its normal position, the sw~tch will still
trip open when the coil is energized.
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 contact~ 46
and 48 whicn, as just described, can be tripped open by
the s~all solenoid mechanis~ 36~ The coil 74 o~ the
solenoid mechanis~ is energized by the electronic
ti~ing circuit 42 (Figure 7) whenever the iron is ~on~
but not moved for a predetermined ti~e interval. This
ti~e interval is typically seven to ten minutes, but
can be of any desired duration. A small ~otion
detector switch MS, which may be a ~ercury ~witch, i~
mounted on the circuit boar~ 40 such that it opens and
closes rando~ly when moved by normal ironing motions.
Each ti~e the switch opens, the electronic timer Ul, is
reset to the start of its timing cycle ~o that with
normal iron use the powerwill never be turned off.
Referring now particularly to Figure 7, a power lead Wl
is connected to the reset switch represented by the
contacts 46 and 48 (see Fi~ure 3-5), a s~ngle pole
switch which is closed to a latched closed condition,
as previously described~ by manually depressing the
rese~ button 68. This reset switch then re~ains closed
until txipped open by the solenoid coil 74 beinq
energized, also as previously described. From the
~2g~
--10-- ~
reset Switch represented by the contacts 46 and 48,
power proceeds through a power lead W2 to an over
te~perature li~iter 84, a ther~ostat 36, and a calrod
heating ele~ent B8 which are all the a~e as in
conventional irons. The other calrod ter~inal is
connected to a power lead W3 and is also the ~co~on~
clrcuit for the electronic circuitryO A capacitor C5
and a Iretal oxide varistor M~ one exall~ple being a
General Electric V13OLA2 MOV, are added acros~ the
10 power leads W2 and W3 for transient ~uppressionO
Whenever the contacts46 and 48areclosed, the user i~
infor~ed that the iron is "on" by the illumination of a
neon bulbN, current flow th~ough which is li~ited by a
resistor R12 in series therewith. With the contacts ~6
and 48 closed, power is also suppl ied to the electronic
circuitry. The resistors Rl and Rll~ diode CRl and
capacitor Cl form a d.c. power supply providing
approxi~ately +11 volts across the capacitor Cl. This
20 voltage is reduced and regulated at 9.1 volts by the
resistor Rlo and the zener diode CR3~ An integrated
circuit timer Ul is used to time the seven to ten
minute turn off delay. An acceptable for~ of the
circuit ti~er Ul is a TLC555C integrated circuit ti~er
~anufactured and sold by Texas Instru~ents, or
equivalent. The capacitor C3 is continually being
cnarged tnrough the resistor R4 and since no base
current is supplied to the transistor Ql~ the
transistor Ql is "of f " and does not discharge the
capacitor C3, The seven to ten ~inute interval is
z~
deterTnined by the time resauired to charge the capacitor
C3 to two-t~lirds the voltage at pins 4 and 8 of the
timer Ul.
S The motion detector switch MS, a smal 1 mercury switch,
as no~ed above, is normally closed and capaci~or C2 is
charged to approxi~a'cely 4 75 vol ts. An acceptabl e
version of the motion detector switch suitable for
purposes of the invention is ~odel TS66 sold by Fifth
Dimension, Inc. of Clintsn, New Jersey. When the iron
20 is moved, as in normal ironing ~otion, the motion
switch ~S opens mo~entarily and capacitor C2 starts to
charge towards approxi~ately 9 volts throuqh the
resistor R2. This charge current i8 also base to
e~itter current in transistor Ql so that the
transistor Ql is turned on, momentarily, thereby
discharging capacitor C3 and thus resetting the timer
Ul. When the ~otion switch MS recloses, capacitor C2
is partially discharged again through the resistor R3,
2~ the ~otion switch MS, and resistor R9, and the
transistor Ql is again turned "o~f~.
The ti~er Ul is connected as a astable oscillator
having its output at pin 3 ~high~ (approxi~ately 9
volts) for seven to ten minutes followed by several
milliseconds Nlow" (approximately 0.1 volts) depending
upon C3/R5 discharge timing~ Resistor R~ deter~ines
the rate at which capacitor C3 is discharged when the
circuit ti~es out because the iron has not been used
for 7 to 10 ~inute~. This insure~ that the SC~ will be
--12--
turned on long enough to always trip the solenoid
actua~ed switch1 The transistor Q~ inverts this
voltage f ro~ pin 3 of the ti~er Ul so that its
collect~r is at a low voltage when pin 3 is high and
high when pin 3 goes low at the end of the ti~ing
period. In this context, resistor R6 is the bia~ing
resi~tor for transistor Q2 when pin 3 i high thereby
li~iting the base current of transistor Q2 to a safe
value. when the collector of the transi~tor Q2 goes
10 "high~, the diode CR2 conducts enough current through
resistor R7 to resistor R~ and to the gate of an ~CR Q3
to cause the SCR gate to turn "on" during positive
half cycles of voltage on the power lead Wl.
Resistor R7 biases the gate o~ SCR Q3 and limits the
collector current to transistor Q2 to a value that
enables the charge on capacitor Cl to last long enough
to insure that the solenoid 36 will trip the switch.
~eavy 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 re~oves power fro~ the
iron heating circuit and fro~ the control circuit.
Capacitors C4 and C6 increase the noise i~munity of the
timer Ul as is well known. Also, a resistor R8
stabilizes the gate of SCR Q3 so that voltage withstand
and dv/dt characteristics are i~provedO
Thus it will be appreciated that the mechanis~
described is a silrple, low cost, low power, ~anually
30 closed but electrically tripped open ~witching device
~2g~3
-13-
which i~ ideally ~ui~ced for electrical appliances such
as a pres~ing 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
5 pushing the reset bu'cton 68. Only a mo~entary current
is used to trigg r the device and allow a previou~ly
stressed spring, na~ely the flexible blade 52, to open
tne power switching contacts 46 & 48.
10 Another, and preerred, e~bodi~ent of the ~echanism of
the invention will now be described with reference to
Figures 6-11. The circuit board 40 supporting all of
tne el~ectronic coll~ponents previously described is
suitably mounted in the handl e portion 28 of the iron
20. As seen in Figure 8, a solenoid ~echanisn~ 102 is
~ounted on the circuit board 40 and includes a plastic
chassis or coil bobbin 104, a coil 106, and an arsrature
108 which ~oves to the left (Figure 8) when the coil
106 is energized.
Just inboard from an end 110 of the circuit board 40
.is an opening 112 (Figure 9) through which a stationary
contact 114 extends, mounted on a suitable support 116
which is suitably fixed to the circuit board. A
25 flexible blade 118 ls bifurcated at a forward end and
nas a pair of tabs 119 at a rearward end received
through openings ll9A in the ci rcuit board ~Figure 9) .
The tabs 119 are bent over and engage the circuit board
to affix the blade thereto. The blade 118 extends
30 forwardly and has ~.ounted thereon a ~ovable contact 120
1~-
whicn i~ engageable with the stationary contact 114~
~owever, the flexible blade 118 is formed of a suitable
spring material biased so that the c~ntact~ 114 and 120
are nor~ally separated unles~ forced together by a~
outside influence,
Such an outside in~luence is in the for~ o~ a latch
122. The latcn 12~ includPs an elongated latch relea~e
spring 124 ~ounted at its rear end to the bobbin 104 of
lû the solenoidl~echanis~ 102 and biased upwardly. Near
its forwardn~ost 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 extre~ity 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 al~o ~ounted
on the pin 128, with one end bearing against the latch
release spring 124 and the other end again~.t 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 o~ the
flexible blade 118. A non-~agnetic extension 140,
preferably of molded plastic ~aterial, at the forward
end of the ar~ature 108 i~ engage~ble with a rear
surace of the latch lever 130 and is selectively
operable to move the foot 132 out of engagement with
3Q tne edge 134.
--15--
A reset button 142 extends through an opening 144 in
the handle portion 28. A peripheral flange 146 on the
button 142 i5 engageable with the opening 144 and
restrains the button against f urther upward travel.
S Since the reset button 142 i~ ~ounted on the upper
surface of a buttsn retainer spring 148, it is, in
effect, captured in place on the handle portion 28.
The retainer spr ng 148 is suikably fastened to the
handle portion 28 Par to the rear of the reset button
142 and at it~ forward end, the button 142 is provided
with a ha~mer 150 which is engageable with an upper
surface of the latch release spring 124.
Tne neon lamp N is illustrated a~ 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 fro~ a translucent ~aterial
and the neon la~p N is positioned beneath the reset
button so as to create a glow in the surface of the
reset button when the la~p is turned on.
As previously explained, a~ter the ixon 20 has re~ained
motionless for the predeter~ined period of ti~e, for
example, 7 to 10 ~inutes, as previously described~ a
25 pulse of electrical energy is directed via the
electronic ci~cuit to the coil 106. The pulse is only
~o~entaryt no greater than one second in durationt and
typically less than 50 milliseconds in durationO When
the coil is thereby energi~ed, the ar~ature 108 is
~agnetically ~oved ~orward (to the left in Figure B)
--16--
toward the center of the coil 106 where the n~agnetic
line~ of force are concentrated and the strongest.
The non-magnetic molded extension 140 thereby engages
tne latch lever 130 pushing it ~orward against the bia~
of the latch spring 133 to unl~tch the foot 132 ~om
the front edge 134 of the printed circui~ board 40.
The f orce of the upward biased 1 atch rel ease spring 124
moves the latch lever 130 upwardly and with it the
latch spring 133. Motion i~ also aided by the upward
bias of the flexible blade 118 which n~oYe~ . upward upon
release of the ~oot 132 and opens the switch contacts
114 and 120 to turn off power to ~he iron.
To restore power to the iron, the user pushes the reset
button 142~ With the downward ll~otion 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
~oard 40. A can~ surface 154 on the foot 132 slides
along the edge 134 until a shoulder 156 is reached
which al 1 ows the latch 1 ever to pivot rea rwardly
(counterclockwise in Figure 11) such that the shoulder
156 firmly engages the undersurface of the printed
circuit board. Thus, once again, the col~tacts 114 and
120 are closed to restore power to the ironO 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 contact~ 114 and 120 are engaged. In
3~
an opposite fashion~ when the contacts 114 and 120 are
openl the neon la~p i5 turned off.
Whil e a 2re~erred en~bodiment of the invention ha~ been
5 disclosed in detail with speci~ic values recited for
certain of the electronic con~ponentæ for greate
understanding, i'c should be understood b~ those skilled
in the art that various ~odif ications may be n~de to
~he illustrated embodiment withou departing ~ro~ the
10 scope of the inv ention as described ~n the
specification and defined in the appended claims.
