GB2340625A

GB2340625A - Countdown timer unit

Info

Publication number: GB2340625A
Application number: GB9814551A
Authority: GB
Inventors: Ronald Weston Gretton
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-06
Filing date: 1998-07-06
Publication date: 2000-02-23
Also published as: GB9814551D0; WO2000002218A1

Abstract

A timer unit 10 includes input pin connectors in the form of a plug for electrically connecting the unit to a domestic power socket. The unit also includes an electrical outlet switch for electrically connecting the input pins to the outlet. A Count-down timer is activated to countdown for a predetermined time period to operate the switch to disconnect the input pin connectors from the outlet. The unit may countdown to connect the power, or may be incorporated in a different part of the supply line.

Description

2340625 A TIMER UNIT This invention relates to a timer unit. More

particularly but not exclusively this invention relates to a timer unit for controlling the operation of a plug-in appliance In the domestic environment it is desirable to control electrical appliances by timers. It is known, for example, to install timers to activate lamps to switch on and off at predetermined times of the day or night, thus indicating occupancy of an empty property.

Such known timers operate in similar ways. The timer mechanism is located in close proximity to the appliance and is manually set to operate at a required time and to switch off at a later time. This manual operation of the timer may be difficult for persons who are disabled or elderly.

Also conventional timers incorporate a clock or counter which requires access to a power supply even when the appliance is switched off.

There is a need for a timer that alleviates the aforementioned problems and provides improvements generally.

According to the present invention there is provided a timer unit including input pin connectors for electrically connecting the unit to a domestic power socket, electrical outlet switch means for electrically connecting said input pins to the outlet of said unit count-down timer means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically isolate said input pin connectors from said outlet.

Also according to the invention there is provided a timer unit including input pin connectors for electrically connecting the unit to a domestic power socket an electrical outlet switch means for electrically connecting said input pins to the outlet of said unit count-down timer means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically connect said input pin connectors to said outlet.

Also according to the invention there is provided a timer unit including means for electrically connecting the unit to a domestic power socket; an electrical outlet; switch means for electrically connecting said timer 15 unit to the electrical outlet; count-down timer means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically isolate the timer unit electrical input from said outlet.

Advantageously the timer device is activated after the mains power is accessed, either through insertion of the plug within the plug socket or through switching the power supply on.

The operation of the timer requires no pre-setting by the user. The timer is simply activated when the power supply is switched on or off.

Advantageously little or no power is used when the pre determined time period of the timer has elapsed.

2 In an embodiment of the invention the timer is incorporated within a plug adapted to be fitted to the mains cable of the appliance. Advantageously the timer and the plug are combined thus providing the dual operation of switching the appliance on for a pre determined length of time.

The count-down timer is one which performs a single operation at the end of the predetermined time period. After the count-down time period has expired power is either provided to the outlet so as to, for example, switch on an appliance connected thereto, or to electrically disconnect power to the outlet thus switching off an appliance connected thereto. The countdown timer must then be reset if it is to perform further functions.

It is also envisaged that the timer unit, activates a power supply to an appliance after the predetermined time period has elapsed.

In an embodiment there is no need for the user to set the timer except by plugging the timer unit into the domestic power supply. The appliance then operates for the length of time indicated on the product or plug/timer.

The invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view of an embodiment of the invention in use with an electrical appliance; Figure 2 is a wiring diagram of the electrical circuit of an embodiment of the invention.

Figure 3 is a perspective view of an in-line adapter incorporating the timer unit of the present invention 3 According to one embodiment of the invention the timer unit 10 shown generally in figure 1 is incorporated within a standard domestic plug 12 or other suitable plug device. The operational time 14 is indicated on the device. The operational time 14 indicates the length of time the appliance 18 will be connected to the power source. The plug and timer are formed as one unit 10 and attached to an appliance cable 16. Power to the plug and timer unit 10 is activated as soon as the plug is located within the socket 20 or if a switch, if available, when the switch is activated. The appliance 18 may be indicated as on or off by indicator lights 22.

Referring to figure 2 timer unit is connected to the mains though a fuse 24 and a filter comprising inductors 26 and capacitors 28. The filter (26, 28) reduces the effect of incoming and outgoing EMI.

The PIC microcontroller 30 is the main controlling element of the circuit. The software including microcontroller 30 performs a number of functions. When the power is switched on, the microcontroller 30 (triac) samples the incoming ac waveform. At the zero crossing the a triac switch 32 activated to power tile load A timer, positioned within the microcontroller 30 is then activated. When the pre-determined time has elapsed the microcontroller again samples the incoming ac waveform. At the zero crossing the triac switch 32 switched off and the microcontroller 30 enters the sleep mode.

Switching the triac 32 when the ac waveform is near zero voltage reduces load turn offlon transients. The timer is derived from the internal MHz oscillator. other input or output ports may be used to select time intervals by linking to reference voltage 34. The microcontroller 30 requires a nominal input of 5v in order to operate. This voltage is derived directly 4 from the mains by a series resistor dropping chain 36. The use of three resistors spreads the energy dissipation. The ac is then half-wave rectified by a diode 38 and smoother by capacitor 40.

The zener diode 42 regulates the dc supply to the microcontroller to a nominal 5v.

Capacitor 44 is mounted as close to the input current supply pins as possible so that it is effective in the case of high energy transients. The zener diode 42 and rectifier diode 38 also advantageously have a protecting effect with the three series resistors 36 absorbing most of the transient energy due to their inherent high value.

This zero-cross sampling circuit provides a unidirectional sample of the incoming ac: waveform at a suitable level as specified by the voltage input/output limits for the microcontroller, for low level triac 30 switching.

The triac 30 is switched on when the ic pin for driving the triac 30 gate falls to zero with respect to reference voltage 34. the triac gate is thus fed from a nominal 5v source between the gate and the cathode. When the ic pin is switched towards the input voltage 46, there will be approximately zero volts between the gate and the cathode and the triac 30 will switch off.

The timer is a solid state timer although any other suitable timer may be employed.

In one embodiment of the invention it is envisaged that the plug and timer 10 may be formed in the shape of numbers which indicate the length of time the appliance 18 will be in operation before resetting of the timer is required. This is particularly advantageous for the partially sighted user.

The different models of timer could also be colour coded, different colours each representing the length of time for which the timer will be activated.

Advantageously the timer unit is not provided with external controls. It is 10 controlled only by access to a power supply or removing the power supplied to the unit.

In another embodiment of the invention the timer unit is formed as an adapter readily connectable to a domestic plug when in use.

Now referring to figure 3 it is envisaged that the timer unit could be incorporated, in one embodiment, within an in-line adapter 50.

In another embodiment of the invention the timer unit 10 could be 20 provided with a rotating encoder switch or knob. This would allow the timer to be easily programmed in prefixed increments as required. For example the increments could be 15, 30, 45, 69, 90, 120 and 150 minutes. The user would need only to decide how long the unit is to be on or off and then set the unit to one of the times offered. Conventional adjustable timers only allow time adjustments in small equal units of time, this applies to both digital and mechanically adjustable versions.

In a further embodiment of the invention a low voltage switching timer could also be utilised. This would allow the switching of the 240 mains 6 supply internally. A modification to the circuit arrangement could be made so that the timer plug could switch low voltage supplies for low voltage driven products without the built-in timer functions. This would be a volt-free switching function for any required voltage.

The timer unit may also incorporate a buzzer to notify the user when the timer period has elapsed.

In use the timer unit 18 is plugged into the mains socket 20 and the timer operation commences. At the end of the countdown period of time 14 the appliance 18 is switched off or on and remains on or off. The timer unit 10 is re-set by removing the plug from the socket 20 and then reinserting it into the socket. The timer will then automatically revert to its start position. It is also envisaged that the timer unit 10 may be reset by operation of a reset button 24. If the user wishes to use the appliance 18 for a length of time longer than the pre-set timer allows then the plug 12 attached to the appliance 18 would need to be unplugged and replugged in to allow the appliance 18 to resume operation.

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Claims

1 A timer unit including input pin connectors for electrically connecting the unit to a domestic power socket; an electrical outlet; switch means for electrically connecting said input pins to the outlet of said unit; count- down timer means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically isolate said input pin connectors from said outlet.

2. A timer unit including input pin connectors for electrically connecting the unit to a domestic power socket; an electrical outlet; switch means for electrically connecting said input pins to the outlet of said unit; count- down timer means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically connect said input pin connectors to said outlet.

3. A timer unit as claimed in claim 1 or claim 2 wherein said timer is deactivated after the countdown predetermined time period has lapsed.

4. A timer unit as claimed in claim 1 wherein the timer is adapted, in use, to co-operate with a domestic plug.

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5. A timer unit as claimed in any one of the preceding claims wherein the electrical outlet is adapted for connection to a -domestic appliance.

6. A timer unit as claimed any one of the preceding claims characterised in that said timer is formed in the shape of the numerals which indicate the predetermined time period of activation of said timer.

7. A timer unit as claimed in any one of the preceding claims wherein the predetermined time period of activation of said timer is non- alterable.

8. A timer unit as claimed in any one of the preceding claims wherein said timer is activated upon insertion of said plug into a domestic mains socket.

9. A timer unit as claimed in any one of the preceding claims wherein the timer is formed in-situ with a domestic appliance plug.

10. A timer unit as claimed in claim 1 or claim 2 wherein the timer is adapted for use with a plug extension socket.

11. A timer unit as claimed in any one of the preceding claims including current sensing means adapted to activate said timer.

12. A timer unit including means for electrically connecting the unit to a domestic power socket; an electrical outlet; switch means for electrically connecting said timer unit to the electrical outlet; 9 count-down thner means said timer means being activated to countdown for a predetermined time period to operate said switch means to electrically isolate the timer unit electrical input from said outlet.

S

13. A timer unit substantially as described herein with reference to the accompanying drawings.