GB2381674A

GB2381674A - Lamp dimmer

Info

Publication number: GB2381674A
Application number: GB0126273A
Authority: GB
Inventors: Lawrence George Gray; Carol Brigid Gray
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-01
Filing date: 2001-11-01
Publication date: 2003-05-07
Anticipated expiration: 2021-11-01
Also published as: GB2381674B; GB0126273D0

Abstract

An electrical control for a lamp having input connections for connecting to a switched electrical power supply and output connections for connecting to a lamp, the control having control means for controlling a power output to the output connections, such that the control has a high power output level and a reduced power output level, and the control means arranged such that when the lamp is operating at one power output level, the other output power level is selectable by means of switching the electrical power supply off and back on.

Description

Improvements in and relating to electrical controls The present invention relates to electrical controls for lighting.

According to the present invention, there is provided an electrical control for a lamp having input connections for connecting to a switched electrical power supply and output connections for connecting to a lamp, the control having control means for controlling a power output to the output connections, such that the control has a high power output level and a reduced power output level, and the control means arranged such that when the lamp is operating at one power output level, the other output power level is selectable by means of switching the electrical power supply off and back on.

A benefit of the invention is that a night light for a child may be provided without disturbing or altering existing switches or wiring. A further benefit is that the adaptor may be controlled by normal I-way or 2-way switching arrangements again with no alterations to switches or wiring (for example for hall and stair lighting, or bedroom lighting with a wall switch adjacent to a door and a ceiling switch adjacent to a bed).

Hence, where used on a two way switched circuit, a further benefit is that the adaptor may be controlled from either switch.

Preferably the control is arranged such that when electrical power is applied to the control having been absent for at least a first period of time the control operates at a first power output level, and when electrical power is applied to the control having been absent for less than a second period of time the control operates at a second power output level, the first period being longer than the second period.

Preferably the control is further arranged to provide at least one intermediate power output level between the high power output level and the reduced power output level,

the intermediate power output level being selectable by means of switching the electrical power supply off and back on.

Preferably the control is arranged such that, when the control is operating at the high power output level or an intermediate power level, and when electrical power is applied to the control having been absent for less than the second period of time the control is arranged to select a next lower power level.

Preferably the control is arranged such that when the control is operating at the reduced power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to continue to operate at this level.

Preferably the control is arranged such that when the control is operating at the reduced power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to select the high power level.

Preferably in a further embodiment the control is arranged such that, when the control is operating at the reduced power output level or an intermediate power level, and when electrical power is applied to the control having been absent for less than the second period of time the control operates to select a next higher power level.

Preferably in the further embodiment the control is arranged such that when the control is operating at the high power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to continue to operate at this level.

Preferably in the further embodiment the control is arranged such that when the control is operating at the high power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to select the reduced power level.

Preferably the first period is two seconds.

Preferably the second period is less than two seconds. More preferably the second period is one and a half seconds A benefit of the first period being two seconds and the second period being one and a half seconds is that a user may easily switch between the power output levels without having to wait a long time.

Preferably the first power output level is a high power output level and the second power output level is a low power output level.

A benefit of the first power output level being a high power output level, is that in locations such as stairwells or bathrooms, where a high power output level is normally required this is always obtained when the lamp is first switched on. A benefit of this is that safety, for example on stairs, is enhanced.

Preferably the electrical power supply is a household mains electrical supply.

Preferably the first power output level is the high power output level and the second power output level is the reduced power output level.

Preferably the first power output level is the reduced power output level and the second power output level is the high power output level.

A benefit of the first power output level being the reduced power output level, is that in locations such as bedrooms, where a low power output level is preferable to avoid disturbing a sleeping occupant, this is always obtained when the lamp is first switched on.

Preferably a selection means is provided to select between a first mode and a second mode of operation, the first mode being when the first power output level is the high power output level and the second power output level is the reduced power output

level, and the second mode being when the first power output level is the reduced power output level and the second power output level is the high power output level.

Preferably the selection means is operated by two consecutive interruptions of the power supply to the adaptor, each interruption being less than the second period, and each interruption occurring within a period no longer than three times the length of the second period.

Preferably the selection means comprises a switch on the control.

Preferably the control is operating at the high power output level, substantially all the power applied to the input connections is transmitted to the output connections.

A benefit of this is that there is no power dissipated in the control. A further benefit is that the high power output level provides a manufacturer's rated light output from a lamp.

Preferably the control has a latching arrangement arranged to unlatch when a time interval equal to or greater than the first period elapses from when the power supply is switched off, and wherein a 555 integrated circuit is arranged to provide the latching arrangement.

Preferably the control has a latching arrangement arranged to latch when the power supply is switched off for a time interval equal to or less than the second period, and wherein a 555 integrated circuit is arranged to provide the latching arrangement.

Preferably the control is provided with an adjustment means for adjusting a preset power level of the reduced power output level.

Preferably the control further comprises a housing having at one end a lamp cap and lamp cap contacts, being the input connections, for connecting the adaptor to a lamp holder, and having at an other end a lamp holder, for receiving a lamp, with lamp holder contacts, being the output connections, in which housing the control means is incorporated, the control means being connected between the lamp cap contacts and the lamp holder contacts and being arranged such that electrical power from the lampholder passes through the control means to a lamp mounted to the lampholder.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which :Figure 1 is a view of a control according to a first embodiment of the invention showing some hidden details in dotted lines; Figure 2 is a circuit diagram of a second embodiment of a control according to the invention; and Figure 3 is a circuit diagram of a third embodiment of a control according to the invention.

From Figure 1, an electrical control 1 for a lamp 9 comprising an adaptor housing 2 having at one end a lamp cap 3 with lamp cap contacts 4 and 5 for connecting the adaptor to a supply lamp holder (not shown), and having at an other end a lamp holder 6 with lamp holder contacts 15 and 16 for receiving the lamp 9. Mounted within the housing is a control means 10, the control means being connected with wires 11 and 12 to the lamp holder contact terminals 13 and 14 which are electrically connected to the lamp holder contacts 15 and 16. The control means 10 is also connected by wires 17 and 18 to the lamp cap contacts 4 and 5, and is arranged so that electrical power from the supply lampholder passes through the control means to the lamp 9.

In use a user will operate a wall switch or a ceiling switch to switch the lamp. If the lamp has been off for a long time, the period will be greater than the first period, hence when the wall switch is operated, the control will supply power to the lamp at the first power output level. If the user wishes to select the second power output level, then it is necessary for the user to briefly interrupt the supply for a short period of time less than the second period, when the control will operate so that power is supplied to the lamp at the second power output level.

The control 1, also has selection means, which is a switch 20 mounted so that it may be operated by a user between a first position 21 and a second position 22. The switch is connected by wires 23,24 and 25 to the control means 10.

When the selection switch 20 is in the first position 21 a first mode of operation is selected and when it is in position 22 a second mode of operation. The control is arranged so that the first mode is when the first power output level is a high power output level and the second power output level is a low power output level, and the second mode is when the first power output level is a low power output level and the second power output level is a high power output level.

A preset potentiometer 29 has a rotatable shaft 26 protruding the adaptor housing.

The potentiometer is connected to the control by means of wires 27 and 28. In use the shaft 26 may be rotated by a user to adjust the power level of the reduced power level.

Hence, the reduced power level may be adjusted to suit the personal preferences of the user.

The control unit or adaptor, as shown in Figure 1, comprises of a small adaptor with a male bayonet fitting at one end and a female fitting at the other. The electronic switching is contained in the small area in between. To make use of this adaptor, the

lamp bulb and shade are removed from the light fitting in the room. The lamp shade is fitted to the adaptor and the bulb is then plugged into the adaptor. The adaptor is then plugged into the room light fitting.

In an embodiment (not shown) the unit may also be built into a small self contained enclosure which may be hard wired into a circuit. It may also be incorporated into a switch, ceiling rose or other similar fitting.

The operation is as follows :- Turn the light on as normal. To activate the night light, simply switch off the light and turn it back on within approximately 1.5 seconds. To revert back to full brilliance turn the light off for about 2 seconds and then back on. A control is provided to preset the low level setting.

A third embodiment which has the same physical appearance and is installed in the same way as the first, is capable of producing a range of different pre-set light levels.

Again-normal operation of the lighting switch will turn the lamp on, To activate the dimmer, simply turn the light switch off and on again within approximately 1.5 seconds and the light will assume its dimmest setting. Each subsequent off and on operation of the light switch will activate the next highest level of lighting until the maximum level is again reached. If full brilliance is required, turn the switch off for approximately 2 seconds and back on again.

A circuit diagram for a second embodiment of a control according to the invention is shown in Figure 2. Full-Dim is built around a 7555 timer chip.

Referring to Figure 2, power is derived from the mains supply via R5 C3 BR1 and Z2 When the power is initially turned on C 1 begins to charge via diode Dl. The reset pin

4 is held low by Rl which keeps the 7555 timer held low by Rl which keeps the 7555 timer in the reset condition until power rail A reaches 3. 9 volts at which point Zl begins to conduct and pin 4 will go high, allowing the chip to function as normal. Pin 2 (trigger) at this point will be over 1/3 of the voltage on power rail A so the state of the 7555 timer will not change. In this state the output pin 3 will be low.

If the mains supply is now switched off for a short period of time (approximately 1.5 seconds or less) and then turned back on, power rail A will be held high for about 2 seconds via Cl but pin 2 of the 7555 timer chip will drop sharply to below 1/3 of supply rail A. This will cause the output at pin 3 to go high. The 7555 will remain in this state until the power is removed completely by switching it off for over 2 seconds.

When the power is first turned on and the output pin 3 is low, the LED in the optoisolator will be turned on-this will cause the triac to fire very early in the A/C cycle thus causing the bulb to be illuminated at full brilliance. When the 7555 output pin 3 is in the high state, the LED will be turned off and consequently the triac will be fired after a time period which is dictated by the R/C combination ofVRl R6 and C4. This will give a dimmed light which can be set in level by VR1.

Bridge rectifier BR2 and changeover switch C/0 enable the switching modes to reversed. Hence, by operating the changeover switch, when the power is first turned on the bulb will be illuminated at the dimmed light level, which is the reduced power output level.

A circuit diagram for a third embodiment of a control according to the invention is shown in Figure 3.

From Figure 3 it may be seen that A/C mains is taken to Bridge rectifier BRI via R13 and C5. The D. C. output from the bridge rectifier is then held at 16 volts by zener diode D 1. The 16 volts DC is then fed to an 8 volt regulator REG 1. The output from the regulator is then split. The supply rail (A) for the integrated circuits is taken from the regulator via D 11 and is fed to a large electrolytic capacitor C3 which will power the circuit for approximately two seconds after the power has been switched off. The other power rail (B) has only a small reservoir capacitor C4 connected to it which will result in this rail dropping sharply when the power is switched off. This rail is used to trigger the switching circuit and to change the states as is required.

On initial power up ICI and IC2 will be reset. R2 initially takes pin 4 (reset) on both integrated circuits to a low state until the rising DC power supply reaches the D I zener breakdown voltage of 3.9 volts when both pins 4 are raised to this level, thereby removing the reset condition from these pins.

IC3 A on power up will have pins 1 and 2 low because the outputs from IC 1 and IC2 are low. Pin 13 ofIC3A will be high from power rail (B). When the power is turned off and back on again within approximately 1.5 seconds, power rail A will stay high enough to maintain power to the main circuit. Pin 13 of IC3A will fall. At this point all inputs will be low causing IC3A output to change state i. e. pin 12 will go high.

This will cause IC3B to change state and pin 8 will go low. This will cause pin 2 of ICI to drop below 1/3 of power rail A causing the output pin 3 to briefly go high.

This output

1. Is fed to pin 1 ofIC3A which will change its output state. As a consequence IC3B will change its output state which will take pin 2 of IC 1 back to the high state, thereby stopping it retriggering and 2. will change the state of IC3C which will cause pin 2 of IC2 to fall briefly to less than 1/3 power rail A causing IC2 to go the SET state. Pin 8 ofIC3C is also used as the falling edge triggering for the next stage. IC2 is now latched with its output being fed to IC3A pin 2. This will stop any further triggering onC1 until such time as the power is turned off for approximately 2 seconds or more and then switched back on, causing pin 6 of IC2 to rise above 2/3 power rail A at which point IC2 will once again resume its RESET state.

IC4 is a 4 bit binary counter giving 16 possible out-, it states. This IC4 is also reset on initial power up by a positive going pulse, provide my C2 and R3. The triggering pulses from the preceding stage is used to step th1 counter up, until a binary count of 8 is reached. At this point output QD will go high and via D2 will provide a positive pulse once again on the reset pin 2 causing this IC to reset.

The outputs QA, QB and QC are fed to a BCD to decimal converter, which will cause the outputs 0-7 to go low one after the other and back to zero on each successive triggering pulse. These 8 outputs are each connected via a resistor and a diode to a common output. Each resistor has a different value which will result in a different voltage being produced at the output for each successive triggering.

Each trigger pulse is the result of the main light switch being turned off and back on within 1.5 seconds. This output voltage is then fed to a voltage controlled dimmer which as a result will produce 8 different light level outputs. The voltage controlled dimmer, which was used in conjunction with this circuit, was based around

information provided by TEMIC semiconductors on their data sheet referring to a phase control, IC number TEA 1007 which they manufacture.

The circuit is set up so that initially on power on, full brilliance is given, the next switching results in minimum brilliance being produced. The subsequent triggerings produce increasing brilliance until full brilliance is once again achieved. At any time this circuit can be reset to produce maximum brilliance by switching off for approximately 2 seconds or more and then back on.

Claims

CLAIMS 1. An electrical control for a lamp having input connections for connecting to a switched electrical power supply and output connections for connecting to a lamp, the control having control means for controlling a power output to the output connections, such that the control has a high power output level and a reduced power output level, and the control means arranged such that when the lamp is operating at one power output level, the other output power level is selectable by means of switching the electrical power supply off and back on.
2. An electrical control for a lamp as claimed in claim 1, wherein the control is arranged such that when electrical power is applied to the control having been absent for at least a first period of time the control operates at a first power output level, and when electrical power is applied to the control having been absent for less than a second period of time the control operates at a second power output level, the first period being longer than the second period.
3. An electrical control for a lamp as claimed in claim 1 or 2, wherein the control is further arranged to provide at least one intermediate power output level between the high power output level and the reduced power output level, the intermediate power output level being selectable by means of switching the electrical power supply off and back on.
4. An electrical control for a lamp as claimed in claim 3 when dependent on claim 2, wherein the control is arranged such that, when the control is operating at the high power output level or an intermediate power level, and when electrical power is applied to the control having been absent for less than the second period of time the control is arranged to select a next lower power level.
5. An electrical control for a lamp as claimed in claim 4, wherein the control is arranged such that when the control is operating at the reduced power output level,

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and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to continue to operate at this level.
6. An electrical control for a lamp as claimed in claim 4, wherein the control is arranged such that when the control is operating at the reduced power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to select the high power level.
7. An electrical control for a lamp as claimed in claim 3 when dependent on claim 2, wherein the control is arranged such that, when the control is operating at the reduced power output level or an intermediate power level, and when electrical power is applied to the control having been absent for less than the second period of time the control operates to select a next higher power level.
8. An electrical control for a lamp as claimed in claim 7, wherein the control is arranged such that when the control is operating at the high power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to continue to operate at this level.
9. An electrical control for a lamp as claimed in claim 7, wherein the control is arranged such that when the control is operating at the high power output level, and when electrical power is applied to the control having been absent for less than the second period of time, the control is arranged to select the reduced power level.
10. An electrical control for a lamp as claimed in any of the claims 2 to 9, when dependant on claim 2, wherein the first period is two seconds.
11. An electrical control for a lamp as claimed in any of the claims 2 to 10, when dependant on claim 2, wherein the second period is one and a half seconds.

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12. An electrical control for a lamp as claimed in any of the preceding claims wherein the electrical power supply is a household mains electrical supply.
13. An electrical control for a lamp as claimed in any of the claims 2 to 12 when dependant on claim 2, wherein the first power output level is the high power output level and the second power output level is the reduced power output level.
14. An electrical control for a lamp as claimed in any of the claims 2 to 12 when dependant on claim 2, wherein the first power output level is the reduced power output level and the second power output level is the high power output level.
15. An electrical control for a lamp as claimed in any of the claims 2 to 12 when dependant on claim 2, wherein a selection means is provided to select between a first mode and a second mode of operation, the first mode being when the first power output level is the high power output level and the second power output level is the reduced power output level, and the second mode being when the first power output level is the reduced power output level and the second power output level is the high power output level.
16. An electrical control for a lamp as claimed in claim 15 when dependant only on claim 2, wherein the selection means is operated by two consecutive interruptions of the power supply to the adaptor, each interruption being less than the second period, and each interruption occurring within a period no longer than three times the length of the second period.
17. An electrical control for a lamp as claimed in claim 15, wherein the selection means comprises a switch on the control.
18. An electrical control for a lamp as claimed in any of the preceding claims, wherein when the control is operating at the high power output level, substantially all the power applied to the input connections is transmitted to the output connections.

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19. An electrical control for a lamp as claimed in any of the preceding claims, wherein the control has a latching arrangement arranged to unlatch when the power supply is switched off for a time interval equal to or greater than the first period, and wherein a 555 integrated circuit is arranged to provide the latching arrangement.
20. An electrical control for a lamp as claimed in any of the preceding claims, wherein the control has a latching arrangement arranged to latch when the power supply is switched off for a time interval equal to or less than the second period, and wherein a 555 integrated circuit is arranged to provide the latching arrangement.
21. An electrical control as claimed in any of the preceding claims, wherein the control is provided with an adjustment means for adjusting a preset power level of the reduced power output level.
22. An electrical control for a lamp as claimed in any of the preceding claims, wherein the control further comprises a housing having at one end a lamp cap and lamp cap contacts, being the input connections, for connecting the adaptor to a lamp holder, and having at an other end a lamp holder, for receiving a lamp, with lamp holder contacts, being the output connections, in which housing the control means is incorporated, the control means being connected between the lamp cap contacts and the lamp holder contacts and being arranged such that electrical power from the lampholder passes through the control means to a lamp mounted to the lampholder.
23. An electrical control for a lamp, substantially as hereinbefore described and with reference to the accompanying drawings.