Dimmer

Abstract

A dimmer 300 for lighting comprises an input terminal 304, configured for connection to a live mains voltage 108; a first wire 306, configured for connection to a first terminal 410 of a user switch 2

Description

Field of the Invention The present invention relates to dimming systems for use in controlling lighting. Specifically, the invention relates to a dimmer for use in a phase-cut dimming system designed to work in conjunction with one or more light switches, allowing a user to control the brightness of the lighting by varying the electrical power delivered to a lighting fixture. Background of the Invention A basic light switch enables a user to perform on / off control for lighting by opening or closing a circuit. A standard lighting circuit comprises a light switch and a lighting fixture. Two wires run to a back-box which is fitted in a wall cavity, for connection to the light switch. The two wires are a live wire and a switched live wire. The live wire is connected to an alternating current (AC) mains supply, and the switched live wire is connected to the lighting fixture. The lighting fixture is also connected to the neutral wire of the AC mains supply. When the light switch closes, the circuit completes, and current flows to the lighting fixture, illuminating the light. While effective for on / off control, such basic lighting systems lack the ability to control the intensity of the lighting, which may be desirable. To address this limitation, dimming technologies have been developed, allowing a user to adjust the brightness of lighting fixtures. Dimming technology also provides the user with the benefit of reducing energy consumption when dimming a light. Two examples of dimming technologies are resistive dimming and phase-cut dimming. Phase-cut dimming has emerged as a widely adopted and efficient method for controlling light intensity in residential, commercial, and industrial settings. Phase-cut dimming works by modifying the AC waveform delivered to the lighting fixture, reducing the power supplied to the lighting fixture and in turn reducing the brightness / intensity. Phase-cut dimming is more efficient than resistive based methods, which dissipate excess energy as heat. The present invention provides an improved dimmer. Summary of the Invention According to a first aspect of the invention there is provided a dimmer for lighting comprising; an input terminal, configured for connection to a live mains voltage; a first wire, configured for connection to a first terminal of a user switch; a second wire, configured for connection to a second terminal of the user switch; a power supply module, comprising a DC output, electrically connected between the input terminal and the first wire, for providing a DC voltage to the DC output; a controller, electrically connected to: the DC output of the power supply module, to receive power from the power supply module; the second wire; the input terminal, to sense a voltage at the input terminal; and the first wire, to sense a voltage at the first wire; and the controller comprising a dimming module control output, the controller being configured to output a control signal to the dimming module control output; a phase-cut dimming module, electrically connected to: the dimming module control output of the controller, to receive the control signal from the controller; the input terminal; and the first wire, the phase-cut dimming module being configured to provide a voltage to the first wire based on the control signal received from the controller. The controller may be configured, in response to a discrete signal received from said user switch, to output a control signal to the phase-cut dimming module to output a maximum voltage to the first wire, or to allow no current to flow to the first wire to turn off the lighting. The controller may be configured, in response to a continuous signal received from said user switch, to output a control signal to the phase-cut dimming module to increase or decrease the voltage to the first wire. The controller may be configured to store a last control signal output to the phase-cut dimming module, prior to turning off the lighting. The controller may be configured to set the control signal to the last control signal output to the phase-cut dimming module prior to turning off the lighting, in response to a discrete signal received from said user switch. According to another aspect of the invention there is provided a dimming system comprising the dimmer as defined above and a user switch. The user switch may be a one-way retractive switch or a two-way retractive switch. Brief Description of the Drawings The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 shows an example of a conventional lighting circuit incorporating a known resistive dimmer switch. Figure 2 shows an example of a conventional lighting circuit utilising a known phase-cut dimmer pack. Figure 3 is a block diagram of a dimmer in accordance with the invention, showing its external connections. Figure 4 shows a wiring configuration of a lighting circuit incorporating the dimmer of Figure 3. Figure 5 is an internal block diagram of the dimmer of Figure 3, detailing its components. Figure 6 shows a wiring configuration of the lighting circuit of Figure 4 when used with a further retractive switch. Detailed Description Figure 1 shows an example of a conventional lighting circuit 100 incorporating a known resistive dimmer switch 102. The lighting circuit 100 comprises a lighting fixture 104, which may be wall or ceiling mounted. The lighting fixture 104 is controlled by a light switch which is mounted at the wall, in this case the resistive dimmer switch 102. The lighting fixture 104 is powered by an AC mains supply 106. The first, live wire 108 of the AC mains supply is connected to an input terminal 110 of the resistive dimmer switch 102. A second wire 112 is connected from an output terminal 114 of the resistive dimmer switch 102 to the first terminal 116 of the lighting fixture 104, and this connection is referred to as “switched live”. A third wire 118 is connected from a second terminal 120 of the lighting fixture to the neutral 122 of the AC mains supply 106. The resistive dimmer switch 102 functions by varying electrical resistance in series with the lighting fixture 104, to regulate power delivery and control brightness. It comprises a variable resistor, such as a rheostat or potentiometer, which is adjusted via a rotary knob or sliding actuator to modify the current flow. Increasing resistance reduces voltage and current to the lighting fixture 104, thereby dimming the brightness, while decreasing resistance allows greater power flow, thereby increasing brightness. Excess energy is dissipated as heat, making the system inefficient compared to modern dimming technologies. While effective for incandescent and halogen lamps, resistive dimmers are generally unsuitable for LEDs, which may require phase-cut dimming for proper operation. Phase-cut dimming (also known as phase-fired control or phase-angle control) is a commonly used method for controlling light intensity. As is known in the art, this technique involves altering the AC waveform supplied to a lighting load to provide power over only a portion of each mains cycle, effectively reducing the electrical energy received by the lamp and thereby adjusting its brightness. In leading-edge dimming, the circuit cuts off the initial portion of the waveform, making it suitable for resistive and inductive loads such as incandescent and halogen lamps. In trailing-edge dimming, the circuit cuts the latter part of the waveform, providing smoother operation and better compatibility with electronic loads, such as LEDs. Figure 2 shows an example of a conventional lighting circuit 200 utilising a known phase-cut dimmer pack. The arrangement of Figure 2 is similar to that of Figure 1, other than the resistive dimmer switch 102 is replaced by a retractive switch 202 and a phase-cut dimmer pack 204. As with the arrangement of Figure 1, the lighting circuit 200 comprises a lighting fixture 104, which may be wall or ceiling mounted. The lighting fixture 104 is controlled by a light switch which is mounted at the wall, in this case the retractive switch 202. The lighting fixture 104 is similarly powered by an AC mains supply 106. The first, live wire 108 of the AC mains supply 106 is connected to an input terminal 210 of the phase-cut dimmer pack 204. A second wire 112 is connected from an output terminal 214 of the phase-cut dimmer pack 204 to a first terminal 116 of the lighting fixture 104, and this connection is referred to as “switched live”. A third wire 118 is connected from a second terminal 120 of the lighting fixture 104 to the neutral 122 of the AC mains supply 106. The retractive switch 202 is connected to the phase-cut dimmer pack 204 through a first wire 222, and a second wire 224. The first 222 and second 224 wires may have current and voltage ratings which are lower than the live wire 108 of the AC mains supply 106, the switched live wire 112 and the wire 118 running from the lighting fixture 104 to the AC mains supply 106. A retractive switch 202 (also known as a momentary switch) is a type of pushbutton switch that returns to its default position when released. Such a switch will momentarily close the circuit when pressed, before returning to an open position. Retractive switches often have three positions (also known as a two-way retractive switch), whereby a rocker switch can be pushed up or down, in both cases returning to a centre position when released. Phase-cut dimmer packs tend to be large units, requiring separate installation from the user switch, and modifications to the standard wiring serving the user switch. The present invention provides a dimmer that utilises phase-cut dimming to control the lighting intensity of one or more lighting fixtures. Figure 3 is a block diagram of a dimmer 300 in accordance with the invention, showing its external connections. The dimmer 300 has a reduced form factor relative to the conventional phase-cut dimmer pack 204 shown in Figure 2. This reduced size enables the dimmer 300 to be located within the wall cavity behind a user switch, occupying the space typically allocated for a conventional light switch and providing the additional benefit of using less material than conventional phase-cut dimmer packs. The compact design facilitates seamless integration into existing electrical installations without necessitating significant modifications to the mounting enclosure or wiring infrastructure. The dimmer 300 comprises three external connections: a terminal 304, a first wire 306, and a second wire 308. The terminal 304 is configured to receive the live wire present within the wall cavity, establishing an electrical connection with the AC mains supply. This provides the benefit of direct connection to the live wire 108 which is typically run to the wall-mounted back-box, without the need for an additional connector block. The first wire 306 is adapted to establish an electrical connection with a first terminal of a user switch, and the second wire 308 is adapted to establish an electrical connection with a second terminal of the user switch. The first 306 and second wires 308 may be insulated with different colour covering, to easily distinguish their functionality. For example, the first wire 306 may be insulated in a grey covering, and the second wire 308 may be insulated in a white covering. This specific configuration facilitates ease of installation by enabling direct integration into existing lighting circuits without the need for additional wiring modifications or coupling connectors beyond those conventionally employed in standard lighting installations. Figure 4 shows a wiring configuration of a lighting circuit 400 incorporating the dimmer 300 of Figure 3. The lighting circuit 400 comprises a lighting fixture 104, which may be wall or ceiling mounted. The lighting fixture 104 is controlled by a retractive switch 202 which is mounted at the wall. The lighting fixture 104 is powered by an AC mains supply 106. The first, live wire 108 of the AC mains supply 106 is connected to the terminal 304 of the dimmer 300. The first wire 306 of the dimmer 300 is connected to a first terminal 410 of the retractive switch 202, and this connection is referred to as the “switched live”. The second wire 308 of the dimmer 300 is connected to a second terminal 414 of the retractive switch 202. A further switched live wire 112 is connected to the first terminal 410 of the retractive switch 202, and to the first terminal 116 of the lighting fixture 104, this being the switched live wire which typically runs from a wall-mounted back-box to a lighting fixture. A neutral wire 118 is connected from a second terminal 120 of the lighting fixture 104 to the neutral 122 of the AC mains supply 106. Figure 5 is an internal block diagram illustrating the components of the dimmer 300 of Figure 3. The dimmer 300 comprises: a power supply module 502, a controller 504, and a phase-cut dimming module 506. The power supply module 502 is electrically connected at its input to the AC mains live voltage provided through the live terminal 304 of the dimmer 300, and at its output to the switched live 112 via the first wire 306 of the dimmer 300. The power supply module 502 is configured to convert mains AC power into direct current (DC) power of around 2.5 V. Other DC voltages may be used, and are likely to be no more than 5 V. This DC voltage is used internally to power the controller 504 with a reduced voltage, via low voltage supply connection 508. The controller 504 is electrically connected to the second wire 308 of the dimmer 300 and is configured to receive control signals from the retractive switch 202 via said second wire 308. The controller 504 processes signal received from the retractive switch 202 to regulate the operation of the phase-cut dimming module 506 accordingly, via a dimming module control connection 510. The controller 504 is further electrically connected to the live and switched live connections (shown in broken lines 512, 514 respectively), but merely to sense the live voltage and the switched live voltage, for precise control of the phase-cut dimming module 506. The phase-cut dimming module 506 is also electrically connected at its input to the AC mains supply 106 provided through the live terminal 304 of the dimmer 300, and at its output to the switched live wire 112 of the lighting circuit 400 via the first wire 306 of the dimmer 300. The phase-cut dimming module 506 is configured to execute phase-cut dimming on the AC mains supply 106, in response to signals received from the controller 504 via the dimming module control connection 510, thereby generating a reduced AC voltage, which is supplied to the switched live wire 112 via the first wire 306 of the dimmer 300. The power supply module 502 provides energy to the controller 504 from the potential difference between the live voltage at terminal 304 and the switched live voltage at the first wire 306 that exists during the part of the mains cycle when the phase-cut dimming module 506 is not conducting. The controller 504 may be configured to interpret user switch inputs in specific ways. For example, the controller 504 may be configured to output a control signal via a dimming module control output to the phase-cut dimming module 506 based on the following interactions with a one-way retractive user switch: • Single press: A single short press can toggle a light on or off. • Hold press: Holding the switch in a prolonged manner sends a continuous signal, which the dimmer pack interprets as a command to gradually increase or decrease the light's brightness. For a two-way retractive switch, the dimmer pack can be programmed to interpret the switch signals in similar ways, for example: • Single press in either direction: A single short press in either direction can toggle the light on or off. • Hold press upwards: Holding the switch in a prolonged manner in the upwards direction sends a continuous signal, which the dimmer pack interprets as a command to gradually increase the light's brightness. • Hold press downwards: Holding the switch in a prolonged manner in the downwards direction sends a continuous signal, which the dimmer pack interprets as a command to gradually decrease the light's brightness. In one embodiment, the user switch is a one-way retractive switch 202. The controller 504 of the dimmer 300 is programmed to interpret the user switch signals in specific ways. A brief actuation of the retractive switch 202 prompts the controller 504 to instruct the phase-cut dimming module 506 to toggle the lighting between on and off states. A prolonged actuation causes the controller 504 to regulate the phase-cut dimming module 506, thereby modulating the generated AC voltage supplied to the switched live connection, resulting in a corresponding increase or decrease in the brightness of the lighting. A double actuation of the retractive switch may be interpreted by the controller 504 as a command to reverse the direction of brightness adjustment during a long press, switching from an increasing to a decreasing brightness level, or vice-versa. In another embodiment, the retractive switch 202 may be a two-way centre-off retractive switch, having two “on” positions. To distinguish between these two positions, a diode is inserted between one terminal of the retractive switch 202 and the second wire 308, to rectify the input signal to the switch when the switch is actuated in a specific position, thereby allowing the control module to distinguish between upward and downward actuation. In such embodiments, the controller 504 of the dimmer 300 is programmed to interpret the switch signals in specific ways. A brief actuation of the retractive switch 202 in either direction prompts the controller 504 to instruct the phasecut dimming 506 module to toggle the lighting between on and off states. A prolonged actuation of the ‘up’ direction of the two-way retractive switch 202 causes the controller 504 to regulate the phase-cut dimming module 506, thereby increasing the generated AC voltage supplied to the switched live connection, resulting in a corresponding increase in the brightness of the lighting. A prolonged actuation of the ‘down’ direction of the two-way retractive switch 202 causes the controller 504 to regulate the phase-cut dimming module 506, thereby decreasing the generated AC voltage supplied to the switched live connection, resulting in a corresponding decrease in the brightness of the lighting. The controller 504 of the dimmer 300 may be programmed to store the most recent power level prior to when the lights were turned off. In this manner when the light is it turned back on it would do so to a dimmed level, rather than to full brightness. In another embodiment, the retractive switch 202 is an intelligent encoder comprising a rotary switch. This type of switch encodes the rotation and / or pressing of a knob into a pattern of conduction periods. In such embodiments, the controller 504 of the dimmer 300 is programmed to interpret the switch signals in specific ways. A brief actuation of the rotary switch prompts the controller 504 to instruct the phase-cut dimming module 506 to toggle the lighting between on and off states. Rotation of the rotary switch in a clockwise direction may cause the controller 504 to regulate the phase-cut dimming module 506, thereby increasing the generated AC voltage supplied to the switched live connection, resulting in a corresponding increase in the brightness of the lighting. Rotation of the rotary switch in an anti-clockwise direction may cause the controller 504 to regulate the phase-cut dimming module 506, thereby decreasing the generated AC voltage supplied to the switched live connection, resulting in a corresponding decrease in the brightness of the lighting. In some aspects, the dimmer 300 may be user-programmable through predefined sequences of actuations of the user switch. User configurable features may include, but are not limited to, adjustment of the maximum brightness level of the lighting, adjustment of the minimum brightness level of the lighting, activation and deactivation of a ‘boost mode’ for certain types of LED lighting, configuration of a timer function to determine the duration for which the lighting remains active, and activation and deactivation of a child lock feature to prevent unintended adjustments or programming. The controller 504 of the dimmer 300 may be configured to automatically detect the type of user switch connected and adjust its programming parameters accordingly. To use a different type of user switch, the dimmer 300 must be restored to its factory settings. A factory reset of the dimmer 300 may be initiated through the execution of a predefined sequence of actuations of the user switch 202. In some embodiments, multiple user switches may be required. Figure 6 shows a wiring configuration 600 of the lighting circuit 400 of Figure 4 when used with a further retractive switch, such as when two user switches are placed at different entrances to a room. The arrangement of Figure 6 shares the connections and components of Figure 4, however allowing control through more than one switch through the use of a further retractive switch 602 connected in parallel to the retractive switch 202. The first terminal 610 of a further retractive switch 602 is electrically connected to the first terminal 410 of the retractive switch 202, via wire (shown in broken line 606), sharing the switched live connection. The second terminal 614 of the further retractive switch 602 is electrically connected to the second terminal 414 of the retractive switch 202, via wire (shown in broken line 608). Due to the further retractive switch 602 being connected in parallel to the retractive switch 202, the further retractive switch 602 is able to control the dimmer 300 in the same manner as retractive switch 202. Various modifications will be apparent to those in the art and it is desired to include all such modifications as fall within the scope of the accompanying claims.

Claims

1. A dimmer (300) for lighting comprising;an input terminal (304), configured for connection to a live mains voltage (108);a first wire (306), configured for connection to a first terminal (410) of a user switch (202);a second wire (308), configured for connection to a second terminal (414) of the user switch (202);a power supply module (502), comprising a DC output, electrically connected between the input terminal (304) and the first wire (306), for providing a DC voltage to the DC output;a controller (504), electrically connected to:the DC output of the power supply module (502), to receive power from the power supply module (502);the second wire (308);the input terminal (304), to sense a voltage at the input terminal(304); andthe first wire (306), to sense a voltage at the first wire (306);the controller (504) comprising a dimming module control output and being configured to output a control signal to the dimming module control output;a phase-cut dimming module (506), electrically connected to:the dimming module control output of the controller (504), to receive the control signal from the controller (504);the input terminal (304); andthe first wire (306),the phase-cut dimming module (506) being configured to provide a voltage to the first wire (306) based on the control signal received from the controller (504).

2. The dimmer (300) as claimed in claim 1, wherein the controller (504) is configured, in response to a discrete signal received from said user switch (202), to output a control signal to the phase-cut dimming module (506) to output a maximumvoltage to the first wire (306), or to prevent current flowing to the first wire (306) to turn off the lighting.

3. The dimmer (300) as claimed in claim 1 or 2, wherein the controller (504) is configured, in response to a continuous signal received from said user switch (202), to output a control signal to the phase-cut dimming module (506) to increase or decrease the voltage to the first wire (306).

4. The dimmer (300) as claimed in claim 1, 2 or 3, wherein the controller (504) is configured to store a last control signal output to the phase-cut dimming module (506), prior to turning off the lighting.

5. The dimmer (300) as claimed in claim 4, wherein the controller (504) is configured to set the control signal to the last control signal output to the phase-cut dimming module (506) prior to turning off the lighting, in response to a discrete signal received from said user switch (202).

6. A dimming system (400) comprising the dimmer (300) as claimed in any one of the preceding claims and a user switch (202).

7. The dimming system (400) as claimed in claim 6, wherein the user switch (202) is a one-way retractive switch.

8. The dimming system (400) as claimed in claim 6, wherein the user switch (202) is a two-way retractive switch.Application No: GB2501689.0Claims searched: 1 to 8Examiner: Mr Tony OldershawDate of search: 10 March 2025Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1 to 8 GB2251727 A (TUCKER) - see figures 3 and 4; page 5 line 14 to page 6 line 7 X 1 to 8 US2018 / 0153021 Al (GOTOU) - see figure 1; paragraphs [0019] to [0034] X 1 to 8 US2013 / 0271025 Al (HORN) - see figures 5 and 6; paragraphs [0008] and [0023] to [0033] X 1 to 8 US2010 / 0145545 Al (M0SEBR00K) - see figure 7A; paragraphs [0085] to [0087] X 1 to 8 US2007 / 0126368 Al (McDONOUGH) - see figures 1 to 3; paragraphs [0012], [0020] and [0034]to[0049] X 1 to 8 US10219353 Bl (LORENZ) - see figures 1 and 5; column 4 lines 4 to 21 X 1 to 8 US10123391 Bl (XIONG) - see figure 1; column 2 line 51 to column 4 line 45 X 1 to 8 US5248919A (HANNA) - see figure 2; column 1 lines 26 to 37, column 3 lines 40 to 52, column 4 lines 23 to 44 and column 5 line 18 to column 7 line 24X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if combined with one or more other documents of same category. P Document published on or after the declared priority date but before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC_____________ H05B___________________________________________________ The following online and other databases have been used in the preparation of this search report SEARCH-PATENTInternational Classification:Subclass Subgroup Valid From H05B 0047 / 10 01 / 01 / 2020

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