CA1197891A - Electronic safety device for an electric flat-iron - Google Patents
Electronic safety device for an electric flat-ironInfo
- Publication number
- CA1197891A CA1197891A CA000446036A CA446036A CA1197891A CA 1197891 A CA1197891 A CA 1197891A CA 000446036 A CA000446036 A CA 000446036A CA 446036 A CA446036 A CA 446036A CA 1197891 A CA1197891 A CA 1197891A
- Authority
- CA
- Canada
- Prior art keywords
- iron
- voltage
- resistor
- contacts
- switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F75/00—Hand irons
- D06F75/08—Hand irons internally heated by electricity
- D06F75/26—Temperature control or indicating arrangements
Abstract
AN ELECTRONIC SAFETY DEVICE FOR
AN ELECTRIC FLAT-IRON
Abstract of the Disclosure A movable body such as a magnet is capable of moving freely on a substantially rectilinear and hori-zontal surface within a housing of a laundry iron when ironing is in progress. The magnet cooperates with a switch associated with a timer for automatically cutting-off the supply of current to the iron at the end of a predetermined period of non-use. A displacement of the magnet either in one direction or in the other produces at least one sequence of opening and closing of the switch contacts for zero-resetting of the timer and maintenance of the current supply to the heating resistor.
AN ELECTRIC FLAT-IRON
Abstract of the Disclosure A movable body such as a magnet is capable of moving freely on a substantially rectilinear and hori-zontal surface within a housing of a laundry iron when ironing is in progress. The magnet cooperates with a switch associated with a timer for automatically cutting-off the supply of current to the iron at the end of a predetermined period of non-use. A displacement of the magnet either in one direction or in the other produces at least one sequence of opening and closing of the switch contacts for zero-resetting of the timer and maintenance of the current supply to the heating resistor.
Description
Thi~ in~ention relates to an elec~ronic safe~y device for an electric f].at-iron. This device per~its automatic interruption of the supply of electric current to the iron at the end of a predetermined interval of non-use~
By way of example, a device of this t~pe ha~
been d~scr1bed in French Cartificate of Utllity No 2 355 113 of June 15, 1977 in the name of Erich R.
BAUMGARTNERand Peter DOEHLER.
~heo~ject contemplated by this device was to prevent accidents by protecting the article to be ironed when the flat-iron is left unattended and i~ th~re fore motionless. In this case the time intexval which elapses prior to interruption of the electric cuxrent supply i5 of short duration and means must be adopted in order to permit reheating of the iron frQ~ the cold s~ate to its operating temperature since the user does not dis-place the iron during this period.
This device utilize~ the motion of a ball placed within a curved tube having a convexity which is directe~
toward the top of the ixon in order to ensure that the bal]. stops at the loweqt point of the tube when the iron i5 not subjected to any mvv. ~nt. l'his position of immobilization of the ball is detected by a time-controlled sc~n~ng de~ice which initiates an interruption of the supply after a predete ~e~ interval of short duration.
The dlsadvantage of this device lies in the fact that it i5 necessaxy to place the ~r~n in an inclined position or on its rear edge when it is desired to heat the sole-plate from the cold state.
The aim of -the present invention is to ovex~ome the draw~acks of the design just described b~ providing a device for automatic interruption of the electric power supply to a flat-iron at the end of a predetermined time interval, thus making it possible to start h~ating of the iron from its normal position.
A further effect of the device in accordance with the invention is the achievement of a substantial economy of electric power consumption.
In accordance with the present invention, -there is provided an electronic safety device for automatically interrupting the supply of electric current to a heating resistor of an iron at the end of the predetermined interval of non-use, said device comprising a movable body which is capable of displacement within a housing of the iron when the iron i~ being moved, said movable body being adapted to control a position of contacts of an associated switch so that at least one opening-closing sequence of said switch contacts is obtained upon displacements o~ said movable body, means associated with said switch consisting of a re istor bridge supplied with a rectified voltage having a value E
and comprising a first resistor and a second resistor in series with said switch contacts, a capacitor being connected to the terminals of said second resistor, a voltage having a value Vo being collected at the terminals of said first resistor, the respective values of said first and second resistors and being such that said voltage ~o is lower than E/2 when said switch contacts are open or closed and higher than E/~ at the time oE
ft~ 3, - 2a -transition of said con-tacts from the open to the closed positionr said voltage Vo being applied to one input of a counter which is reset to zero each time said voltage vo is higher than E/2, said eounter being connected to an input of a comparator for trans-mitting a voltage Vl when said counter attains a predetermined counting threshold, sa.id eomparator being connected to a trigger of a triac having one terminal connected to a current supply and another terminal connected in series to said heating resistor, said comparator being adapted to deliver turn-on pulses to said trigger as long as no voltage Vl is applied and to stop said turn-on pulses as soon as a voltage Vl is applied to said one input of said comparator, thereby interrupting the eurren-t supply to the heating resistor.
The device eontemplated by the invention for automatic interruption of the power supply to an electrie flat-iron at the end of a predetermined interval of non-use comprises a movable body whieh is capable of displacement within a housing of the iron when the iron itself is being moved at the time of ironing. Said movable body is adapted to cooperate with a switch associated with a timer which is eapable of initiating interruption of the power supply to the iron at the end of a predetermined time interval.
In accordance with the invention, said device is distinguished by the fact that the switch cooperates with the movable body so that at least one openin~ and closing movement of the switeh eontaets is obtained at the time of displacement of said movable body either in or.e direetion or in the other. Means associated with said , ~ . ~ ~
switch are provided for ensuring that the aforementioned opening-closing sequence of the contacts initia-tes re-setting of the timer to zero and main-tenance of the electric power supply to the heating resistor of the iron.
~uring each displacement in either one direction or in the other, the switch contacts carry out at least one opening-closing sequence for resetting of the timer which would otherwise initiate interruption of the power supply to the heating resistor at the end of a predeter-mined time interval.
When -the iron is turned-on in the cold state, however, no special position of the iron is required since the predetermined time interval which elapses prior to cutoff is su~ficient to bring the iron -to the preselected temperature. In practice, this time interval is of the order of five minutes.
In a preferred embodiment of the invention, the means associated with the switch consist of a resistor bridye supplied with a rectified voltage E and comprising in series a resistor Rl, the contacts of a magnetic reed switch, a resistor R2 having a substantially higher value than the resistor Rl, a capacitor C being connected to the terminals o~ said resistor R2. A voltage signal Vo is collected at the terminals of the resistor Rl and applied to one input of the timer which is responsive to a voltage signal of higher value than E/2. Said signal Vo , ,.
~'7~
is always lower than E/2 when the contacts are open or closed and ass~mes a value higher than E/2 only at the time of transition of said contacts from the open position to the closed position.
Under these conditions, only a displacement of the movable permanent magnet causes the emission of a signal which actuates the timer, the rest positions of the magnet being without effect on the switch, whether said positions correspond to either open or closed contacts of said switch.
Other features of the invention will be more appare~t upon consideration of the following description and accompanying drawings, wherein :
- FigO l is a partial longitudinal sectional view of a flat-iron in accordance with the invention ;
- Fig. 2 is a sect:Lonal view taken along the plane II-II of Fig. l ;
- Fig. 3 is a schematic view oF a reed switch so arranged as to cooperate with a movable magnet within a housing and illustrates the operation of the device ;
- Fig. ~ is a diagram which is similar to Fig. 3 and shows the position of the reed-swi.tch contacts in the open position (O) or in the closed position (F) as a function of the positions of the magnet within its housing ;
- Fig. 5 is an electric circuit diagram of a resistor bridge controlled by ~he reed-switch contacts for zero-resetting of the timer ;
- FigO 6 represents the voltage signal Vo applied to the counter at the time of a sequence of opening closing of the reed-switch contacts ;
- Fig. 7 provides a general schematic circuit diagram of the device in accordance with the invention ;
- Fig. 8 is a perspective diagram showing the contact-reed and magnet assembly.
In the embodiment of Figs 1 and 2, the flat-iron 1 is provided with a power supply cable 2 and a handle 3 formed, for example, o~ plastic material molded in two parts which fit one inside the other. The handle is of hollow construction and contains the device in accordance with the invention for automatic interruption of the electric power supply to the iron at the end of a pre-determined time interval. This device comprises a plurality oE electronic circuits represented schematically in Fig. 7 a~d mounted on a printed-circuit board 4. These electronic circuits mainly comprise a triac 5 controlled by a comparator ~, a bridge for measuring the temperature o~ the sole-plate of the iron 7, a pulse counter 8 controlled by an oscillator 9, a display device 10 for indicating the temperature ~ones and the state of the iron, for example by means o~ lignt-emitting diodes, and a circuit ~or controlling the zero-reset of the r3~
counter 11 comprising a switch 12. The complete circuitry is supplied from an alternating-current voltage source 14.
The switch 12 consists of a magne-tic reed switch of a known type, the contacts 13 of which are open in the rest position and are sealed within a glass tube 16 which may be either evacuated or Eilled with an inert gas for protecting them both mechanically and chemically.
These contacts 13 are of magnetic material and define a contact zone represented by the chain-dotted line 15. Said contacts are influenced by a magnet, the axis of magnet-ization 18 of which is perpendicular to the contact reeds or strips of the switch 12.
The aforementioned magnet 17 is cylindrical and capable of inertial rolling motion on a substantially rectilinear and horizontal surface 20 within a housing 19 when the iron is moved. The cross-section of the housing 19 is slightly larger than the axial cross-section of the magnet 17 in order to permit free displacement oi this latter between the end walls 21 and 22 of the housing (as shown in Figs. 3 and 4) and the thickness of the magnet is preferably smaller than its diameter in order to facilitate its displacement. The housing 19 is sub-stantially parallel to the longitudinal axis of the iron and is placed in a parallel position with respect to the sealed tube 12. The length of said housing is such that, at the time of displacement of the magnet 17, the axis oE
magnetization 18 scans a zone located on each side of the make zone 15 of -the contacts 13. Said housing is attached in a suitable manner to -the top wall of the handle 3 of the iron as well as to the printed-circuit board 4 ~as shown in Figs. 1 and 2).
Fig. 3 shows the north-pole face (N) and the south-pole Eace (S~ of the magnet. 17 and also shows in dashed outline the lines of force of the magnetic field produced by said magnet. It is apparent from this figure that a north-seeking pole is formed on each contact 13 since the axis of magnetization 18 is very close to the co~tact zone 15 of the contacts and that a repulsive force is consequently exerted between these contacts, which accordingly results in opening of the circuit of the switch 12.
Fig. 4 s a schematic diagram showing the open positlon (0) or closed position (F) of the contacts 13 as a function of the different possible positions of the maynet 17 within its housing. When the magnet 17 is located on the extreme right-hand side of its housing 20, it is not sufficiently powerful to influence the contacts 13 and these latter are therefore naturally open. When the magnet 17 moves to the left from a given position of the magnetiæation axis 18 represented by the chain-dot~ed line 23, the magnetic -Eield is closed by the two flexible contact-reeds and forms a south pole and a north pole -8~
respectively on the contacts 1~. Attraction and closing of the contacts then takes place when the restoring force exerted by the reeds is overcome. When the magnet comes very close to the contactzone 15 of the con-tacts 13, namely starting from the chain-dotted line 24 as indicated earlier with reference to Fig 3, the contacts 13 open and remain open until the axis of magnet:ization 18 passes beyond the threshold position represented by a chain-dotted line 25 in Fig. 4. Beyond this threshold, opposite poles are again formed on the contacts 13, thus resulting in attraction and closure. Similarly, when the magnet 17 continues to move towards the left within the housing 20, its influence decreases and the contacts 13 open after the axis of magnetization 18 has passed beyond the position represented by the chain-dotted line 26.
The same cycle of switching of contacts 13 takes place in a displacement in a direction opposite to that described in the foregoing. Thus, when the magnet 17 undergoes a displacement within the housing 20 either in one direction or in the other according to the direction oE displacement of the iron, ~aid magnet initiates at least one sequence of opening and closing of the reed contacts 13.
Reference being made to Figs. 5 and 6, it will now be shown that the above--mentioned sequence produces a zero-reset of the timer which is constituted by the pulse :, 7~
_9_ counter 8 and the 7.ero-reset control circuit 11 of said counter as shown in Figs. 5 and 7.
The zero-reset circuit 11 comprises a resistor bridge Rl, R2 ~ed by a source of direct-current voltage E
which is obtained after rectification from the alternating-current power supply 14 (as shown in Fig. 5). This voltage is delivered via a so-called voltage-dropping resistor 27 a rectifier diode 29 and an electrolytic smoothing capacitor 28.
Said resistor bridge comprises in series a resistor R1, the contacts 13 of the reed switch 12 and a resistor R2, a capacitor C being connected to the terminals of said resistor R2. A voltage signal Vo is collected at the terminals of the resistor Rl and delivered to terminal No 6 of the pulse counter 8.
Resetting of the counter 8 takes place when a voltage signal having a value slightly higher than E/2 is delivered to the te.rminal. No 6.
When the flat-iron is at rest, the contacts 13 can be eikher open or closed according to the position of the magnet 17 within its housing. If the contacts are closed, the voltage at the terminals o.~ the resistor R
assumes a value V0 = E. Rl/(Rl ~ R2).
By way of exampler if a value of resistance which is substantially double that of the resistor Rl is chosen for the resistor R2, it is apparent that the ,,:
~'7~
voltage Vo is equal to approximately E/3, with the result that the counter is not reset to zero.
If the contacts 13 are open, the voltage at the terminals of the resistor Rl is zero~ thus resulting in continued operation of the counter as well as its counting cycle.
On the other hand, at the time of transition at the instant tl (as shown in Fig. 6) from opening to closing of the contacts 13 produced by displacement of the magnet 17 in front of the reed switch 12, there takes place a sharp rise in voltage from O to ~ E at the terminals of the resistor Rl, this rise being followed in the example chosen by a progressive drop in said voltage to an asymptotic value E/8 as established beforehand when the capacitor C is completely chargedO
Said voltage pulses E are applied to input No 6 of the counter 8 and reset said counter which is controlled by the oscillator 9.
If no voltage pulse E is applied to terminalNo 6 at the end of a predetermined time interval o~ the order of Eive minutes, the counter 8 delivers a voltage signal Vl via its output No 8 to terminal No 6 of the comparator 6.
Moreover, said comparator 6 is responsive to the unbalance of the temperature-measurement bridge 7 which is connected to inputs No 7 and No 8 of said .
comparator. This measuring bridge mainly comprises a potentiometer 31 for regulating the temperature of the sol~-plate of the iron and a thermistor 32 for measuring this temperature. As long as the preselected tempexature has not been reached, turn-on pulses are delivexed to the trigger of the triac 5 via output No 15 of the comparator 6. When this temperature is reached, the measuring bridge 7 interrupts the delivery o~ these pulses and the heating resis~or 30 is no longer supplied with current. Similarly, when a voltage signal Vl is applied to terminal No 6 of ~he comparator 6, said signal interrupts the delivery of turn-on pulses to the triac 5 and consequently interrupts the supply of current to the heating resistor 30. At the same time, the comparator 6 initiates turn-on o~ a lightemitting diode 34 in order to provide a visual indication of this state of the iron.
A single subsequent displacement of the magnet 17 within its housing 21 will be sufficient to initiate a sequence o~ opening~closing oE the contacts 13, thus resultiny in resettlny of the counter 8 and delivery oE
turn-on pulses to the triac 5 via the comparator 6 as well as extinction of the corresponding diode 34 The device further comprises an electrolytic capacitor 33 for maintaining the supply of current to the counter 8 in the event of a brief failure of the power sy~tem or line supply. This capacitor enables the counter 8 to memorize ., -12~
it5 state until the voltage of the line supply 14 is restored (over a -time interval of about five seconds, for example).
The efects and advantages of this device are as ~ollows :
When the iron is switched-on, the user is not obliged by the saety device to place the iron in a particular position in order to permit heating of the iron to the preselected temperature.
.~oreover, the electric circuit adopted for the counter-reset control circuit is not affected by the position o the magnet Said circuit is responsive only to the displacement oE the magnet, with the result that -the safety device in accordance with the invention operates irrespective of the position in which the iron may be left unattended.
In this case, the supply is cut-off at the end of a time interval of the order of five minutesl thus avoiding any unnecessary consumption of electricity. The saEe assurance that the supply of current will be cut off at the end of a relatively short period of time brings appreciable peace of mind in the event, for example, that the user has been called away to other unEoreseen occupations and has left the iron turned-on. The user has no reason to be anxious o~er any need to disconnect the iron since interruption o its current supply takes 7~
place automatically.
Finally, the reed switch adopted for the con-struction of the device in accordance with the invention is a device of reliable and rugged design which is capable of withstanding millions of operations, with the result that its service life is as long if not longer than the other electrical or electronic components of the iron.
As will be readily apparent, the present invention is not limited to the embodiments described in the foregoing and many othe.r alternative forms of con-struction may accordingly be contemplated.
Thus it follows that the reed switch 12 and its control magnet 17 could be replaced by a ball or a cylinder which are capable of rolling within a suitable housing and the displacement of which would have the effect, for example, of depressing a flexible finger extending across the rolling surface provided for said ball or cylinder in order to initiate opening and then closing of an associated contact.
Thls assembly could be replaced by a contactless switch o.~ the photodiode type associated with a light-emitting diode placed on each sLde of the housing provided for the movable body, the light beam of the light-emitting diode being interrupted by the passage of the opaque ball or cylinder which moves within its housing.
~9t7~
This assembly could also be replaced by a drop of mercury which slides alony the bottom of a horizontal glass tube, two short metal electrodes being sealed in the bottom wall of the tube in order to be put into electrical contact with each other by the mercury as it passes during displacement of the flat-iron.
Similarly, the counter of the timing device could be replaced by an RC circuit in which a charged capacitor C is discharged through a resistor R, the resistor and the capacitor being calculated so as to obtain the predetermined time interval for operation of the comparator or of a suitably adapted relay and for cutting-out the resistor of the flat-iron.
The surEace for rectilinear displacement of the magnet 17 or of the movable body could have a low slope in order to give said movable body a preferential position of rest without thereby entailing any disadvantages in regard to the operation of the device. The only condition to be observed is that the above-mentioned slope should be sufficiently low to ensure that, during a normal displace-ment of the iron, the movable body should be set in motion and produce at least one sequence of opening-closing oE
the controlled switch.
By way of example, a device of this t~pe ha~
been d~scr1bed in French Cartificate of Utllity No 2 355 113 of June 15, 1977 in the name of Erich R.
BAUMGARTNERand Peter DOEHLER.
~heo~ject contemplated by this device was to prevent accidents by protecting the article to be ironed when the flat-iron is left unattended and i~ th~re fore motionless. In this case the time intexval which elapses prior to interruption of the electric cuxrent supply i5 of short duration and means must be adopted in order to permit reheating of the iron frQ~ the cold s~ate to its operating temperature since the user does not dis-place the iron during this period.
This device utilize~ the motion of a ball placed within a curved tube having a convexity which is directe~
toward the top of the ixon in order to ensure that the bal]. stops at the loweqt point of the tube when the iron i5 not subjected to any mvv. ~nt. l'his position of immobilization of the ball is detected by a time-controlled sc~n~ng de~ice which initiates an interruption of the supply after a predete ~e~ interval of short duration.
The dlsadvantage of this device lies in the fact that it i5 necessaxy to place the ~r~n in an inclined position or on its rear edge when it is desired to heat the sole-plate from the cold state.
The aim of -the present invention is to ovex~ome the draw~acks of the design just described b~ providing a device for automatic interruption of the electric power supply to a flat-iron at the end of a predetermined time interval, thus making it possible to start h~ating of the iron from its normal position.
A further effect of the device in accordance with the invention is the achievement of a substantial economy of electric power consumption.
In accordance with the present invention, -there is provided an electronic safety device for automatically interrupting the supply of electric current to a heating resistor of an iron at the end of the predetermined interval of non-use, said device comprising a movable body which is capable of displacement within a housing of the iron when the iron i~ being moved, said movable body being adapted to control a position of contacts of an associated switch so that at least one opening-closing sequence of said switch contacts is obtained upon displacements o~ said movable body, means associated with said switch consisting of a re istor bridge supplied with a rectified voltage having a value E
and comprising a first resistor and a second resistor in series with said switch contacts, a capacitor being connected to the terminals of said second resistor, a voltage having a value Vo being collected at the terminals of said first resistor, the respective values of said first and second resistors and being such that said voltage ~o is lower than E/2 when said switch contacts are open or closed and higher than E/~ at the time oE
ft~ 3, - 2a -transition of said con-tacts from the open to the closed positionr said voltage Vo being applied to one input of a counter which is reset to zero each time said voltage vo is higher than E/2, said eounter being connected to an input of a comparator for trans-mitting a voltage Vl when said counter attains a predetermined counting threshold, sa.id eomparator being connected to a trigger of a triac having one terminal connected to a current supply and another terminal connected in series to said heating resistor, said comparator being adapted to deliver turn-on pulses to said trigger as long as no voltage Vl is applied and to stop said turn-on pulses as soon as a voltage Vl is applied to said one input of said comparator, thereby interrupting the eurren-t supply to the heating resistor.
The device eontemplated by the invention for automatic interruption of the power supply to an electrie flat-iron at the end of a predetermined interval of non-use comprises a movable body whieh is capable of displacement within a housing of the iron when the iron itself is being moved at the time of ironing. Said movable body is adapted to cooperate with a switch associated with a timer which is eapable of initiating interruption of the power supply to the iron at the end of a predetermined time interval.
In accordance with the invention, said device is distinguished by the fact that the switch cooperates with the movable body so that at least one openin~ and closing movement of the switeh eontaets is obtained at the time of displacement of said movable body either in or.e direetion or in the other. Means associated with said , ~ . ~ ~
switch are provided for ensuring that the aforementioned opening-closing sequence of the contacts initia-tes re-setting of the timer to zero and main-tenance of the electric power supply to the heating resistor of the iron.
~uring each displacement in either one direction or in the other, the switch contacts carry out at least one opening-closing sequence for resetting of the timer which would otherwise initiate interruption of the power supply to the heating resistor at the end of a predeter-mined time interval.
When -the iron is turned-on in the cold state, however, no special position of the iron is required since the predetermined time interval which elapses prior to cutoff is su~ficient to bring the iron -to the preselected temperature. In practice, this time interval is of the order of five minutes.
In a preferred embodiment of the invention, the means associated with the switch consist of a resistor bridye supplied with a rectified voltage E and comprising in series a resistor Rl, the contacts of a magnetic reed switch, a resistor R2 having a substantially higher value than the resistor Rl, a capacitor C being connected to the terminals o~ said resistor R2. A voltage signal Vo is collected at the terminals of the resistor Rl and applied to one input of the timer which is responsive to a voltage signal of higher value than E/2. Said signal Vo , ,.
~'7~
is always lower than E/2 when the contacts are open or closed and ass~mes a value higher than E/2 only at the time of transition of said contacts from the open position to the closed position.
Under these conditions, only a displacement of the movable permanent magnet causes the emission of a signal which actuates the timer, the rest positions of the magnet being without effect on the switch, whether said positions correspond to either open or closed contacts of said switch.
Other features of the invention will be more appare~t upon consideration of the following description and accompanying drawings, wherein :
- FigO l is a partial longitudinal sectional view of a flat-iron in accordance with the invention ;
- Fig. 2 is a sect:Lonal view taken along the plane II-II of Fig. l ;
- Fig. 3 is a schematic view oF a reed switch so arranged as to cooperate with a movable magnet within a housing and illustrates the operation of the device ;
- Fig. ~ is a diagram which is similar to Fig. 3 and shows the position of the reed-swi.tch contacts in the open position (O) or in the closed position (F) as a function of the positions of the magnet within its housing ;
- Fig. 5 is an electric circuit diagram of a resistor bridge controlled by ~he reed-switch contacts for zero-resetting of the timer ;
- FigO 6 represents the voltage signal Vo applied to the counter at the time of a sequence of opening closing of the reed-switch contacts ;
- Fig. 7 provides a general schematic circuit diagram of the device in accordance with the invention ;
- Fig. 8 is a perspective diagram showing the contact-reed and magnet assembly.
In the embodiment of Figs 1 and 2, the flat-iron 1 is provided with a power supply cable 2 and a handle 3 formed, for example, o~ plastic material molded in two parts which fit one inside the other. The handle is of hollow construction and contains the device in accordance with the invention for automatic interruption of the electric power supply to the iron at the end of a pre-determined time interval. This device comprises a plurality oE electronic circuits represented schematically in Fig. 7 a~d mounted on a printed-circuit board 4. These electronic circuits mainly comprise a triac 5 controlled by a comparator ~, a bridge for measuring the temperature o~ the sole-plate of the iron 7, a pulse counter 8 controlled by an oscillator 9, a display device 10 for indicating the temperature ~ones and the state of the iron, for example by means o~ lignt-emitting diodes, and a circuit ~or controlling the zero-reset of the r3~
counter 11 comprising a switch 12. The complete circuitry is supplied from an alternating-current voltage source 14.
The switch 12 consists of a magne-tic reed switch of a known type, the contacts 13 of which are open in the rest position and are sealed within a glass tube 16 which may be either evacuated or Eilled with an inert gas for protecting them both mechanically and chemically.
These contacts 13 are of magnetic material and define a contact zone represented by the chain-dotted line 15. Said contacts are influenced by a magnet, the axis of magnet-ization 18 of which is perpendicular to the contact reeds or strips of the switch 12.
The aforementioned magnet 17 is cylindrical and capable of inertial rolling motion on a substantially rectilinear and horizontal surface 20 within a housing 19 when the iron is moved. The cross-section of the housing 19 is slightly larger than the axial cross-section of the magnet 17 in order to permit free displacement oi this latter between the end walls 21 and 22 of the housing (as shown in Figs. 3 and 4) and the thickness of the magnet is preferably smaller than its diameter in order to facilitate its displacement. The housing 19 is sub-stantially parallel to the longitudinal axis of the iron and is placed in a parallel position with respect to the sealed tube 12. The length of said housing is such that, at the time of displacement of the magnet 17, the axis oE
magnetization 18 scans a zone located on each side of the make zone 15 of -the contacts 13. Said housing is attached in a suitable manner to -the top wall of the handle 3 of the iron as well as to the printed-circuit board 4 ~as shown in Figs. 1 and 2).
Fig. 3 shows the north-pole face (N) and the south-pole Eace (S~ of the magnet. 17 and also shows in dashed outline the lines of force of the magnetic field produced by said magnet. It is apparent from this figure that a north-seeking pole is formed on each contact 13 since the axis of magnetization 18 is very close to the co~tact zone 15 of the contacts and that a repulsive force is consequently exerted between these contacts, which accordingly results in opening of the circuit of the switch 12.
Fig. 4 s a schematic diagram showing the open positlon (0) or closed position (F) of the contacts 13 as a function of the different possible positions of the maynet 17 within its housing. When the magnet 17 is located on the extreme right-hand side of its housing 20, it is not sufficiently powerful to influence the contacts 13 and these latter are therefore naturally open. When the magnet 17 moves to the left from a given position of the magnetiæation axis 18 represented by the chain-dot~ed line 23, the magnetic -Eield is closed by the two flexible contact-reeds and forms a south pole and a north pole -8~
respectively on the contacts 1~. Attraction and closing of the contacts then takes place when the restoring force exerted by the reeds is overcome. When the magnet comes very close to the contactzone 15 of the con-tacts 13, namely starting from the chain-dotted line 24 as indicated earlier with reference to Fig 3, the contacts 13 open and remain open until the axis of magnet:ization 18 passes beyond the threshold position represented by a chain-dotted line 25 in Fig. 4. Beyond this threshold, opposite poles are again formed on the contacts 13, thus resulting in attraction and closure. Similarly, when the magnet 17 continues to move towards the left within the housing 20, its influence decreases and the contacts 13 open after the axis of magnetization 18 has passed beyond the position represented by the chain-dotted line 26.
The same cycle of switching of contacts 13 takes place in a displacement in a direction opposite to that described in the foregoing. Thus, when the magnet 17 undergoes a displacement within the housing 20 either in one direction or in the other according to the direction oE displacement of the iron, ~aid magnet initiates at least one sequence of opening and closing of the reed contacts 13.
Reference being made to Figs. 5 and 6, it will now be shown that the above--mentioned sequence produces a zero-reset of the timer which is constituted by the pulse :, 7~
_9_ counter 8 and the 7.ero-reset control circuit 11 of said counter as shown in Figs. 5 and 7.
The zero-reset circuit 11 comprises a resistor bridge Rl, R2 ~ed by a source of direct-current voltage E
which is obtained after rectification from the alternating-current power supply 14 (as shown in Fig. 5). This voltage is delivered via a so-called voltage-dropping resistor 27 a rectifier diode 29 and an electrolytic smoothing capacitor 28.
Said resistor bridge comprises in series a resistor R1, the contacts 13 of the reed switch 12 and a resistor R2, a capacitor C being connected to the terminals of said resistor R2. A voltage signal Vo is collected at the terminals of the resistor Rl and delivered to terminal No 6 of the pulse counter 8.
Resetting of the counter 8 takes place when a voltage signal having a value slightly higher than E/2 is delivered to the te.rminal. No 6.
When the flat-iron is at rest, the contacts 13 can be eikher open or closed according to the position of the magnet 17 within its housing. If the contacts are closed, the voltage at the terminals o.~ the resistor R
assumes a value V0 = E. Rl/(Rl ~ R2).
By way of exampler if a value of resistance which is substantially double that of the resistor Rl is chosen for the resistor R2, it is apparent that the ,,:
~'7~
voltage Vo is equal to approximately E/3, with the result that the counter is not reset to zero.
If the contacts 13 are open, the voltage at the terminals of the resistor Rl is zero~ thus resulting in continued operation of the counter as well as its counting cycle.
On the other hand, at the time of transition at the instant tl (as shown in Fig. 6) from opening to closing of the contacts 13 produced by displacement of the magnet 17 in front of the reed switch 12, there takes place a sharp rise in voltage from O to ~ E at the terminals of the resistor Rl, this rise being followed in the example chosen by a progressive drop in said voltage to an asymptotic value E/8 as established beforehand when the capacitor C is completely chargedO
Said voltage pulses E are applied to input No 6 of the counter 8 and reset said counter which is controlled by the oscillator 9.
If no voltage pulse E is applied to terminalNo 6 at the end of a predetermined time interval o~ the order of Eive minutes, the counter 8 delivers a voltage signal Vl via its output No 8 to terminal No 6 of the comparator 6.
Moreover, said comparator 6 is responsive to the unbalance of the temperature-measurement bridge 7 which is connected to inputs No 7 and No 8 of said .
comparator. This measuring bridge mainly comprises a potentiometer 31 for regulating the temperature of the sol~-plate of the iron and a thermistor 32 for measuring this temperature. As long as the preselected tempexature has not been reached, turn-on pulses are delivexed to the trigger of the triac 5 via output No 15 of the comparator 6. When this temperature is reached, the measuring bridge 7 interrupts the delivery o~ these pulses and the heating resis~or 30 is no longer supplied with current. Similarly, when a voltage signal Vl is applied to terminal No 6 of ~he comparator 6, said signal interrupts the delivery of turn-on pulses to the triac 5 and consequently interrupts the supply of current to the heating resistor 30. At the same time, the comparator 6 initiates turn-on o~ a lightemitting diode 34 in order to provide a visual indication of this state of the iron.
A single subsequent displacement of the magnet 17 within its housing 21 will be sufficient to initiate a sequence o~ opening~closing oE the contacts 13, thus resultiny in resettlny of the counter 8 and delivery oE
turn-on pulses to the triac 5 via the comparator 6 as well as extinction of the corresponding diode 34 The device further comprises an electrolytic capacitor 33 for maintaining the supply of current to the counter 8 in the event of a brief failure of the power sy~tem or line supply. This capacitor enables the counter 8 to memorize ., -12~
it5 state until the voltage of the line supply 14 is restored (over a -time interval of about five seconds, for example).
The efects and advantages of this device are as ~ollows :
When the iron is switched-on, the user is not obliged by the saety device to place the iron in a particular position in order to permit heating of the iron to the preselected temperature.
.~oreover, the electric circuit adopted for the counter-reset control circuit is not affected by the position o the magnet Said circuit is responsive only to the displacement oE the magnet, with the result that -the safety device in accordance with the invention operates irrespective of the position in which the iron may be left unattended.
In this case, the supply is cut-off at the end of a time interval of the order of five minutesl thus avoiding any unnecessary consumption of electricity. The saEe assurance that the supply of current will be cut off at the end of a relatively short period of time brings appreciable peace of mind in the event, for example, that the user has been called away to other unEoreseen occupations and has left the iron turned-on. The user has no reason to be anxious o~er any need to disconnect the iron since interruption o its current supply takes 7~
place automatically.
Finally, the reed switch adopted for the con-struction of the device in accordance with the invention is a device of reliable and rugged design which is capable of withstanding millions of operations, with the result that its service life is as long if not longer than the other electrical or electronic components of the iron.
As will be readily apparent, the present invention is not limited to the embodiments described in the foregoing and many othe.r alternative forms of con-struction may accordingly be contemplated.
Thus it follows that the reed switch 12 and its control magnet 17 could be replaced by a ball or a cylinder which are capable of rolling within a suitable housing and the displacement of which would have the effect, for example, of depressing a flexible finger extending across the rolling surface provided for said ball or cylinder in order to initiate opening and then closing of an associated contact.
Thls assembly could be replaced by a contactless switch o.~ the photodiode type associated with a light-emitting diode placed on each sLde of the housing provided for the movable body, the light beam of the light-emitting diode being interrupted by the passage of the opaque ball or cylinder which moves within its housing.
~9t7~
This assembly could also be replaced by a drop of mercury which slides alony the bottom of a horizontal glass tube, two short metal electrodes being sealed in the bottom wall of the tube in order to be put into electrical contact with each other by the mercury as it passes during displacement of the flat-iron.
Similarly, the counter of the timing device could be replaced by an RC circuit in which a charged capacitor C is discharged through a resistor R, the resistor and the capacitor being calculated so as to obtain the predetermined time interval for operation of the comparator or of a suitably adapted relay and for cutting-out the resistor of the flat-iron.
The surEace for rectilinear displacement of the magnet 17 or of the movable body could have a low slope in order to give said movable body a preferential position of rest without thereby entailing any disadvantages in regard to the operation of the device. The only condition to be observed is that the above-mentioned slope should be sufficiently low to ensure that, during a normal displace-ment of the iron, the movable body should be set in motion and produce at least one sequence of opening-closing oE
the controlled switch.
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electronic safety device for automatically interrupt-ing the supply of electric current to a heating resistor of an iron at the end of the predetermined interval of non-use, said device comprising a movable body which is capable of displacement within a housing of the iron when the iron is being moved, said movable body being adapted to control a position of contacts of an associated switch so that at least one opening-closing sequence of said switch contacts is obtained upon displacements of said movable body, means associated with said switch consisting of a resistor bridge supplied with a rectified voltage having a value E
and comprising a first resistor and a second resistor in series with said switch contacts, a capacitor being connected to the terminals of said second resistor, a voltage having a value Vo being collected at the terminals of said first resistor, the respective values of said first and second resistors and being such that said voltage Vo is lower than E/2 when said switch contacts are open or closed and higher than E/2 at the time of transition of said contacts from the open to the closed position, said voltage Vo being applied to one input of a counter which is reset to zero each time said voltage Vo is higher than E/2, said counter being connected to an input of a comparator for trans-mitting a voltage V1 when said counter attains a predetermined counting threshold, said comparator being connected to a trigger of a triac having one terminal connected to a current supply and another terminal connected in series to said heating resistor, said comparator being adapted to deliver turn-on pulses to said trigger as long as no voltage V1 is applied and to stop said turn-on pulses as soon as a voltage V1 is applied to said one input of said comparator, thereby interrupting the current supply to the heating resistor.
and comprising a first resistor and a second resistor in series with said switch contacts, a capacitor being connected to the terminals of said second resistor, a voltage having a value Vo being collected at the terminals of said first resistor, the respective values of said first and second resistors and being such that said voltage Vo is lower than E/2 when said switch contacts are open or closed and higher than E/2 at the time of transition of said contacts from the open to the closed position, said voltage Vo being applied to one input of a counter which is reset to zero each time said voltage Vo is higher than E/2, said counter being connected to an input of a comparator for trans-mitting a voltage V1 when said counter attains a predetermined counting threshold, said comparator being connected to a trigger of a triac having one terminal connected to a current supply and another terminal connected in series to said heating resistor, said comparator being adapted to deliver turn-on pulses to said trigger as long as no voltage V1 is applied and to stop said turn-on pulses as soon as a voltage V1 is applied to said one input of said comparator, thereby interrupting the current supply to the heating resistor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR83.01601 | 1983-02-02 | ||
| FR8301601A FR2540148B1 (en) | 1983-02-02 | 1983-02-02 | ELECTRONIC SECURITY DEVICE FOR ELECTRIC IRON |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1197891A true CA1197891A (en) | 1985-12-10 |
Family
ID=9285527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000446036A Expired CA1197891A (en) | 1983-02-02 | 1984-01-25 | Electronic safety device for an electric flat-iron |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4520257A (en) |
| EP (1) | EP0115982B1 (en) |
| JP (1) | JPS59155300A (en) |
| CA (1) | CA1197891A (en) |
| DE (2) | DE3462526D1 (en) |
| ES (1) | ES529357A0 (en) |
| FR (1) | FR2540148B1 (en) |
Families Citing this family (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4686352B1 (en) * | 1984-04-27 | 1993-12-14 | Sunbeam Corporation | Electronic pressing iron |
| JPS612900A (en) * | 1984-06-14 | 1986-01-08 | 松下電器産業株式会社 | Iron |
| JPH034237Y2 (en) * | 1984-09-19 | 1991-02-04 | ||
| JPS638399Y2 (en) * | 1984-11-02 | 1988-03-14 | ||
| JPS61181499A (en) * | 1985-02-06 | 1986-08-14 | 松下電器産業株式会社 | Unuse sensor for iron |
| JPS61257699A (en) * | 1985-05-10 | 1986-11-15 | 松下電器産業株式会社 | Iron |
| JPS61280898A (en) * | 1985-06-06 | 1986-12-11 | 松下電器産業株式会社 | Power source cutting forget detection circuit of iron |
| JPS6249899A (en) * | 1985-08-30 | 1987-03-04 | 松下電器産業株式会社 | Iron having function detecting forgetting power source cut-off |
| US4661685A (en) * | 1985-09-06 | 1987-04-28 | John Zink Company | Electronic pressing iron |
| FR2591246B1 (en) * | 1985-12-06 | 1988-07-08 | Labo Electronique Physique | ELECTRIC IRON WITH AN AUTOMATIC SAFETY DEVICE |
| CA1262378A (en) * | 1986-01-22 | 1989-10-17 | Harry Albinger, Jr. | Automatic switching apparatus for an electrical appliance |
| FR2593637A1 (en) * | 1986-01-29 | 1987-07-31 | Seb Sa | Safety device to ensure the automatic cutting of the electrical supply to a mobile heating appliance, in particular an iron |
| US4673798A (en) * | 1986-04-02 | 1987-06-16 | John Zink Company | Dual temperature electric curling iron having a safety shut-off circuit |
| US4727240A (en) * | 1986-08-11 | 1988-02-23 | Black & Decker Inc. | Electric iron with dual automatic cutoff |
| IT211107Z2 (en) * | 1986-09-25 | 1989-02-13 | Elvio Bernardi | SAFETY DEVICE FOR FERRIDA IRON IN GENERAL |
| EP0268244B1 (en) * | 1986-11-20 | 1991-05-15 | Ernst Peiniger GmbH Unternehmen für Bautenschutz | Safety device |
| DE3715497A1 (en) * | 1987-05-09 | 1988-11-17 | Braun Ag | SAFETY SWITCHING DEVICE FOR CONTROLLING A POWER CONSUMER |
| US4785197A (en) * | 1987-08-20 | 1988-11-15 | Pulse Electronics, Inc. | Tilt switch |
| DE9004538U1 (en) * | 1990-04-21 | 1990-08-02 | W. Guenther Gmbh, 8500 Nuernberg, De | |
| JPH0321300A (en) * | 1990-05-30 | 1991-01-30 | Sanyo Electric Co Ltd | Electric iron |
| FR2664387B1 (en) * | 1990-07-03 | 1992-10-23 | Cogema | DEVICE FOR MONITORING THE ABSENCE OF MOVEMENT OF A PORTABLE ELECTRIC APPARATUS. |
| GB2250755A (en) * | 1990-12-05 | 1992-06-17 | Superluck Electrics Corp | An ultrasonic iron |
| GB9115902D0 (en) * | 1991-07-23 | 1991-09-04 | Global Domestic Prod Ltd | Electrical heating elements |
| ES2036934B1 (en) * | 1991-10-07 | 1996-07-01 | Fagor S Coop Ltda | "SAFETY SWITCHING DEVICE FOR ELECTRIC PLATES" |
| US5209343A (en) * | 1992-01-21 | 1993-05-11 | Comus International | Electrical tilt switch |
| US5380983A (en) * | 1993-07-12 | 1995-01-10 | Black & Decker Inc. | Electrical appliance having user proximity sensor |
| US5595672A (en) * | 1994-05-19 | 1997-01-21 | Pentalpha Enterprises Ltd. | Automatic power interrupting apparatus for an electric appliance |
| US5751074A (en) * | 1995-09-08 | 1998-05-12 | Edward B. Prior & Associates | Non-metallic liquid tilt switch and circuitry |
| US5637931A (en) * | 1996-01-31 | 1997-06-10 | Lundar Electric Industrial Co., Ltd. | Safety apparatus for an electrical iron |
| US5852279A (en) * | 1996-10-02 | 1998-12-22 | Windmere Corporation | Clothes iron with automatic shut off system controlled by multiple switches |
| FR2778679B1 (en) * | 1998-05-12 | 2002-01-18 | Moulinex Sa | ELECTRIC IRON |
| US6104009A (en) * | 1998-12-07 | 2000-08-15 | Hp Intellectual Corp. | Electrical appliance having user proximity sensor |
| WO2014196847A1 (en) * | 2013-06-06 | 2014-12-11 | Universite Internationale De Rabat | Smart iron |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2382587A (en) * | 1942-06-12 | 1945-08-14 | Albert G Thomas | Electric iron |
| US2470532A (en) * | 1943-08-14 | 1949-05-17 | Albert G Thomas | Electric iron with thermokinetic switch |
| US3601729A (en) * | 1969-11-03 | 1971-08-24 | Western Sales Corp | Switch assembly |
| GB1406314A (en) * | 1972-10-03 | 1975-09-17 | Coupe N T | Tilt warning apparatus |
| DE2627158C2 (en) * | 1976-06-16 | 1983-06-30 | Braun Ag, 6000 Frankfurt | Iron without significant heat storage capacity with a safety switch-off device located in the heating circuit |
| US4203101A (en) * | 1977-01-11 | 1980-05-13 | Towsend Marvin S | Electric power interrupting apparatus |
| DE2750546A1 (en) * | 1977-11-11 | 1979-05-17 | Braun Ag | IRON WITH ONE CONTROL CIRCUIT FOR THE SIMULTANEOUS OPERATION OF AT LEAST TWO CONTROL CIRCUITS |
| US4243875A (en) * | 1978-11-13 | 1981-01-06 | Chang Daniel C | Temperature control for resistance heating element |
| DE2902817A1 (en) * | 1979-01-25 | 1980-08-07 | Bosch Gmbh Robert | Vehicle motion and stop detector - has vibrator and reed switch and retriggerable monostable multivibrator sensing switch state |
| US4366366A (en) * | 1980-09-05 | 1982-12-28 | Ekblad Carl A | Electric iron stand with time delay safety switch arrangement |
| WO1982003520A1 (en) * | 1981-04-07 | 1982-10-14 | Robert C Franklin | Appliance non-use detection safety power shut-off system |
| JPS5985700A (en) * | 1982-11-08 | 1984-05-17 | 松下電器産業株式会社 | Iron |
-
1983
- 1983-02-02 FR FR8301601A patent/FR2540148B1/en not_active Expired
-
1984
- 1984-01-20 EP EP84400124A patent/EP0115982B1/en not_active Expired
- 1984-01-20 DE DE8484400124T patent/DE3462526D1/en not_active Expired
- 1984-01-20 DE DE198484400124T patent/DE115982T1/en active Pending
- 1984-01-25 CA CA000446036A patent/CA1197891A/en not_active Expired
- 1984-01-26 US US06/574,140 patent/US4520257A/en not_active Expired - Fee Related
- 1984-02-01 JP JP59015291A patent/JPS59155300A/en active Pending
- 1984-02-01 ES ES529357A patent/ES529357A0/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59155300A (en) | 1984-09-04 |
| DE3462526D1 (en) | 1987-04-09 |
| ES8500365A1 (en) | 1984-10-01 |
| ES529357A0 (en) | 1984-10-01 |
| EP0115982A1 (en) | 1984-08-15 |
| US4520257A (en) | 1985-05-28 |
| FR2540148B1 (en) | 1986-03-21 |
| EP0115982B1 (en) | 1987-03-04 |
| FR2540148A1 (en) | 1984-08-03 |
| DE115982T1 (en) | 1984-12-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1197891A (en) | Electronic safety device for an electric flat-iron | |
| US6452501B1 (en) | Automatic shut-off and indication device for an electric heating appliance and electric pressing iron comprising such a device | |
| US4803342A (en) | Flat-iron safety device utilizing a dual internal timing circuit | |
| US4727240A (en) | Electric iron with dual automatic cutoff | |
| EP0362845A3 (en) | Remote-controlled circuit breaker | |
| DE3787059T2 (en) | Circuit breaker. | |
| BR8200555A (en) | ELECTRIC CIRCUIT SWITCH | |
| JPS5743135A (en) | High frequency heating device | |
| US4366678A (en) | Temperature control apparatus for refrigerating machine | |
| GB1442962A (en) | Vacuum cleaner having a motor temperature sensing device | |
| ES544426A0 (en) | PROTECTION CIRCUIT OF AN ELECTRIC MOTOR | |
| JPS5692557A (en) | Copying machine | |
| JPS5576578A (en) | Overdischarge-preventing circuit for battery | |
| JPS5640917A (en) | Temperature control circuit of heater | |
| JPS52106447A (en) | Solid state power relay | |
| JPS5572733A (en) | Electric floor heater | |
| JPS6477887A (en) | Heater control device | |
| JPS5566713A (en) | Karman vortex value sensor | |
| JP2715687B2 (en) | Iron | |
| SU1082571A1 (en) | Soldering device | |
| SU645087A1 (en) | Thermoanemometric transducer | |
| JPS55155453A (en) | Electric field emission type electron gun | |
| JPS57132233A (en) | Keyboard device | |
| KR790001475Y1 (en) | Automatic-stopping device of driving source on hoisiery knitting m/c | |
| JPS561279A (en) | Welding device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |