AU2017201031A1 - An indicator for a dimming system - Google Patents

Abstract

Abstract An indicator for a dimming system for controlling a load, the dimming system including at least one dimmer connected in series with the load and an alternating current (AC) source, wherein the at least one dimmer has a user interface and a dimmer circuit for controlling AC to the load, and wherein the dimmer circuit includes: an AC switch for switching the AC to the load at a conduction angle to control the load, wherein the indicator includes: an indicator controller configured to determine a duty cycle of a zero-crossing signal of the AC to the load in response to user input of the user interface selecting the conduction angle to control the load; and an indicator display for displaying an indication of a level of the AC conducted to the load based on the duty cycle. C:\poi\word\SPEC-1 042467.docx Si|Si) l' Figure 1A Figure 1B User interface Line In Sl I Controller AC switch Indicator Indicator - -Controller Display 16 18.12 14 - - - - - - - --- Line Out Figure 2 Power Zero-cross Indicator Indicator I supply detection Drive Display circuit circuit Circuit Figure 3

Description

1 2017201031 16 Feb 2017

An indicator for a dimming system Technical Field [0001 ] The present invention relates to an indicator for a dimming system for controlling a load. In particular, but not exclusively, the present invention relates to an indicator for a dimmer with an indicator display, such as an LED graph display, for displaying an indication of a level of alternating current (AC) mains power conducted to the load based on a duty cycle of a zero-crossing signal of the AC to the load.

Background of Invention [0002] Dimmers typically include a dimmer circuit and a user interface (e.g. a rotary knob) to control power, in particular alternating current (AC) mains power, to a load, such as a light source. In one existing example of a dimmer, a light source can be dimmed using a phase controlled dimmer, whereby power provided to the load is controlled by varying the amount of time that a switch connecting the load to a mains power source is conducting during a cycle of the AC (e.g. varying the duty cycle of the AC). Specifically, in this example, AC power to the load is switched ON and OFF during each half cycle of AC and the amount of dimming of the load is provided by the amount of ON time in relation to the OFF time for each half cycle.

[0003] Phase control dimmer circuits generally operate as trailing edge or leading edge dimmer circuits, and the two circuits are suited to different applications. In leading edge circuits, power is switched OFF at the beginning of each half cycle. In trailing edge circuits, power is switched OFF later in each half cycle (e.g. towards the end of each half cycle). Leading edge dimmer circuits are generally better suited to controlling power to inductive loads, such as small fan motors and iron core low voltage lighting transformers. Trailing edge dimmer circuits, on the other hand, are generally better suited to controlling power to capacitive loads, such as drivers for Light Emitting Diode (LED) lights.

[0004] In some applications, the level of the AC conducted to the load as controlled by a dimmer is not readily discernible to a user. For example, the level of the AC conducted to the load is not readily discernible in the application where the dimming system includes more than one user interface for a dimmer to control the 2 2017201031 16 Feb 2017 load. Also, in the example where the load is a fan motor, the level of AC conducted to the fan motor is not immediately discernible to a user.

Summary of Invention [0005] Accordingly, in one aspect of the present invention, there is provided an indicator for a dimming system for controlling a load, the dimming system including at least one dimmer connected in series with the load and an alternating current (AC) source, wherein the at least one dimmer has a user interface and a dimmer circuit for controlling AC to the load, and wherein the dimmer circuit includes: an AC switch for switching the AC to the load at a conduction angle to control the load, wherein the indicator includes: an indicator controller configured to determine a duty cycle of a zero-crossing signal of the AC to the load in response to user input of the user interface selecting the conduction angle to control the load; and an indicator display for displaying an indication of a level of the AC conducted to the load based on the duty cycle.

[0006] In an embodiment, the indicator is connected in parallel with the at least one dimmer. For example, the indicator is connected in parallel with 3 dimmers for controlling a light source in a room. Alternatively, the indicator is integral with each dimmer in the dimming system. In any event, the indicator indicates to the user the level of AC conducted to the load, which is especially useful where the level of AC conducted to the load is not immediately discernible to a user. For example, the indicator could be used and co-located with a dimmer of a light source where the dimmer and the light source are in different rooms, and the indicator display displays an indication of the brightness of the light source to the user.

[0007] In an embodiment, the indicator display is an LED display. Further, the LED display is an LED graph display including a plurality of LEDs indicating the level of the AC conducted to the load to the user. For example, there are 9 LEDs indicating the level of the AC conducted to the load to the user by illuminating 1 to 9 of the LEDs based on the level. Also, when the AC is not conducted to the load and it is in the OFF state, all the LEDs are off. Alternatively, the indicator display is a seven-segment numerical display and the level of the AC conducted to the load is displayed 3 2017201031 16 Feb 2017 to the user as numbers ranging from 1 to 9 indicative of the level (e.g. brightness of light source).

[0008] As above, the at least one dimmer of the dimming system is typically a leading edge phase control dimmer or a trailing edge phase control dimmer. These dimmers can be 2 or 3-wire phase control dimmers. In an example, the dimming system includes a leading edge phase control dimmer for controlling power to a fan motor, and an indicator wired in parallel to the dimmer to display an indication of the fan speed to a user of the dimmer. In another example, the dimming system includes a single trailing edge phase control dimmer for controlling power to drivers for Light Emitting Diode (LED) lights and one indicator is wired in parallel to this dimmer to indicate brightness of the LED lights to a user. In yet another example, the dimming system includes a plurality of trailing edge phase control dimmers for controlling power to drivers for Light Emitting Diode (LED) lights, and an indicator is wired in parallel to the plurality of dimmers to indicate brightness of the LED lights to a user.

[0009] In the example where the indicator is connected in parallel with a plurality of trailing edge phase control dimmers, the indicator can be used to indicate the load conduction angle as determined by any one of the dimmers. In this embodiment, the dimming system is a system as described in co-pending Australia patent application 2015902150, the contents of which are incorporated herein by way of reference. In this system, the plurality of dimmers are connected in series with the load and an alternating current (AC) source, and each of the plurality of dimmers are connected in parallel with each other. As above, each of the plurality of dimmers has a user interface and a dimmer circuit for controlling AC to the load and the dimmer circuit includes: an AC switch for switching the AC to the load at a conduction angle to control the load, whereby the AC is conducted to the load in an ON state and not conducted to the load in an OFF state; and a controller configured to control the load. Specifically, the controller is configured to determine the conduction angle of the load to control turn-ON at each half cycle of the AC source to control switching of the ON and OFF states of the AC switch based on at least a user control signal from the user interface indicating the conduction angle of the load, detect a zero-crossing of the AC to the load, and track the conduction angle of the load by detecting change in the conduction angle of the load based on the zero-crossing of the AC to the load, so that if the controller of an initiating one of the plurality of dimmers determines a new 4 2017201031 16 Feb 2017 conduction angle of the load based on the user control signal, the controller of the initiating one of the dimmers uses the new conduction angle, the controller of each of the plurality of dimmers except the initiating one of the dimmers detects a change in the conduction angle of the load in response to the new conduction angle, and the controller of each of the plurality of dimmers except the initiating one of the dimmers adopts the new conduction angle. That is, in this system, the indicator is configured to display an indication of the level of the AC conducted to the load (e.g. brightness of an LED light source) corresponding to the new conduction angle.

[0010] Also, the indicator controller includes a number of circuits to operate the indicator display. In one embodiment, the indicator includes a zero-crossing detection circuit configured to detect a zero-crossing of the AC to the load so as to generate the zero-crossing signal. Alternatively, the indictor controller can utilise the zero-crossing detection circuit of the dimmer circuit to generate the zero-crossing signal. It will be appreciated by those persons skilled in the art that a zero crossing occurs when the dimmer terminal instantaneous voltage is substantially close to zero, e.g. less than 10V. It will also be appreciated that the duty cycle is a periodic rectangular waveform with a frequency double that of the mains (AC) voltage, with a duty cycle that follows the dimmer conduction angle and hence the load conduction angle. Accordingly, the level of the AC conducted to the load for display to the user can be derived from the duty cycle signal.

[0011] In an embodiment, the indicator controller also includes a power supply circuit configured to provide power for the indicator when the AC is not conducted to the load. Alternatively, the dimmer circuit includes a power supply circuit configured to provide power for the indicator and the dimmer when the AC is not conducted to the load.

[0012] In an embodiment, the indicator controller includes an indicator drive circuit configured to drive the indicator display to display the level of the AC conducted to the load according to a drive level based on the duty cycle of the zero-crossing signal. In one example, the indicator drive circuit is configured to determine the drive level by converting the duty cycle to an analogue drive signal for an indicator display in the form of an analogue display, such as an analogue meter. In another example, the indicator drive circuit is configured to determine the drive level by measuring the duty 5 2017201031 16 Feb 2017 cycle and forming levels, such as levelsl to 9, corresponding to value ranges of the duty cycle, e.g. level 1: level 1: duty cycle 11 -20%; level 2: duty cycle 21 -30%; level 3: duty cycle 31 -40%; level 4: duty cycle 41 -50%; level 5: duty cycle 51 -60%; level 6: duty cycle 61 -70%; level 7: duty cycle 71-80%; level 8: duty cycle 81 -90%; level 9: duty cycle 91 -100%. In the example, the indicator drive circuit includes a microprocessor configured to measure the duty cycle and form the levels.

[0013] In addition, the level of the AC conducted to the load that is displayed to the user is preferably selected to suit the typical load conduction angle range achievable by the dimmer based on the load. For example, the lower and upper limits of typical trailing edge type dimmers for an LED light source is different than the limits of typical leading edge phase dimmers for fan motor speed control or on-off control. That is, the indicator is configured to be tuned to minimum and maximum load conduction angles to suit that of the dimmer type controlling the load.

[0014] It will be appreciated by those persons skilled in the art that the indicator controller can be implemented by a microprocessor or by analogue circuits. Similarly, the dimmer circuit can either be implemented by a microprocessor or analogue circuits to control the load.

Brief Description of Drawings [0015] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0016] Figure 1A shows an indicator for a dimming system for controlling a load according to an embodiment of the present invention; [0017] Figure 1B shows an indicator for a dimming system for controlling a load according to another embodiment of the present invention; [0018] Figure 2 shows a block diagram of the indicator and the dimmer of the dimming system of Figure 1A; [0019] Figure 3 shows a further block diagram of the indicator of Figure 2; [0020] Figure 4 shows a block diagram of an embodiment of the indicator and the dimmer of the dimming system of Figure 1B; and 6 2017201031 16 Feb 2017 [0021 ] Figure 5 shows a block diagram of another embodiment of the indicator and the dimmer of the dimming system of Figure 1B.

Detailed Description [0022] Figures 1A and 1B show embodiments of a dimming system 10 10’ for controlling a load. The dimming system 10 of Figure 1A includes one dimmer Si connected in series with the load and an alternating current (AC) source, and an indicator I connected in parallel with the at least one dimmer Si. As above mentioned above, in another embodiment, the dimming system 10 can include a plurality of dimmers Si-Sn, whereby each of the plurality of dimmers Si-Sn are connected in parallel with each other and the plurality of dimmers Si-Sn are connected in series with the load and the alternating current (AC) source, and the indicator I is connected in parallel with the plurality of dimmers Si-Sn- The dimming system 10’ of Figure 1B includes one dimmer S-Γ connected in series with the load and the alternating current (AC) source, and an indicator Γ integral with the dimmer S-Γ. Again, as above mentioned above, in the embodiment where the dimming system 10’ of Figure 1B includes a plurality of dimmers S-ι—Sn\ and each of the plurality of dimmers S-ι—Sn’ are connected in parallel, each of the dimmers S-t-Sn’ has an indicator Γ integral thereto.

[0023] Also as discussed above, in one example, the load is a driver for LED lights and the user controls the brightness of the LED lights using the dimmer Si and views an indication of the brightness of the LED lights via the indicator display. In this case, the dimmer Si is preferably a trailing edge phase control dimmer for controlling the LED lights. In another example, the load is a fan motor for a fan and the user controls the fan motor speed of the fan using the dimmer Si and views an indication of the fan speed via the indicator display. In this case, the dimmer Si is preferably a leading edge phase control dimmer for controlling the fan motor speed.

[0024] Figures 2 and 4 show both embodiments of the indicator I Γ in more detail. Both embodiments of the indicator I Γ include an indicator controller 12 12’ configured to determine a duty cycle of a zero-crossing signal of the AC to the load in response to user input of the user interface 20 20’ selecting the conduction angle to control the load, and an indicator display 14’ for displaying an indication of a level of the AC conducted to the load based on the duty cycle. With reference to the above 7 2017201031 16 Feb 2017 examples, the indication of the level of the AC conducted to the LED lights or fan motor is indicative of the brightness of the LED lights or the fan speed of the fan motor.

[0025] In one embodiment, the indicator display 14 14’ is an LED graph display including a plurality of LEDs indicating the level of the AC conducted to the LED lights or fan motor to the user to indicate brightness of fan speed to the user. As above, for example, there are 9 LEDs indicating the brightness of the LED light load or fan load speed to the user by illuminating 1 to 9 of the LEDs based on the level of AC conducted thereto as controlled by the dimmer Si Sr.

[0026] Referring back to Figure 2, the indicator I is connected in parallel with a dimmer Si which includes a dimmer circuit 11 for controlling the load. The dimmer circuit 11 includes a controller 16 configured to control an AC switch 18 configured to switch the AC to the load at a conduction angle to control the load. It will be appreciated that the AC is conducted to the load in an ON state and not conducted to the load in an OFF state. That is, the controller 16 controls delivery of the AC to the load in response to input from a user on the user interface 20, such as a rotary knob. The controller 16 controls the turn-OFF and turn-ON of the AC switch 18 at each cycle of the AC to control switching of the ON and OFF states. Also, the dimming circuit 11 further includes a rectifier for rectifying the AC in the OFF state (nonconduction period) to generate rectified dimmer voltage to be provided to the dimmer circuit 11. It will be appreciated by those persons skilled in the art that many circuits of the dimmer circuit 11 do not affect operation of the indicator I and thus will not be discussed in detail herein.

[0027] Figure 3 shows the indicator I of Figure 2 as a stand-alone indicator connected in parallel to the dimmer Si and shows the indicator controller 12 in more detail. The indicator controller 12 includes a number of circuits to provide the indicator display 14 to the user. The indicator controller 12 includes a power supply circuit 22 including, for instance, a rectifier as mentioned above to generate rectified voltage to be provided to the indicator I when the AC is not conducted to the load and the load is in the OFF state. The indicator controller 12 also includes a zero-crossing detection circuit 24 configured to detect a zero-crossing of the AC to the load so as to generate the zero-crossing signal. In the embodiments shown in Figures 4 and 5, the 8 2017201031 16 Feb 2017 power supply circuit and or the zero-crossing detection circuit are provided as part of the indicator controller 12’ as part of the dimmer circuit 11 ’ and are not shown.

[0028] The indicator controller 12 shown in Figure 3 also includes an indicator drive circuit 26 configured to drive the indicator display 14 to display the level of the AC conducted to the load according to a drive level based on the duty cycle of the zero-crossing signal. In one embodiment, the indicator drive circuit 26 is configured to determine the drive level by measuring the duty cycle signal using a microprocessor.

[0029] As described, the indicator I Γ for a dimming system 10 10’ can be used for controlling different types of loads. In one example, the dimming system 10 10’ includes the dimmer Si Sr connected in series with one of the loads and a 50Hz AC source having a 10ms line voltage half-cycle period. That is, the indicator controller 12 12’ determines a duty cycle of a zero-crossing signal of the AC to the load in response to user input of the user interface selecting the conduction angle to control the load, and the useful dimming range over the 10ms line voltage half cycle (e.g. absolute conduction period) differs for different load types.

[0030] In an example of an incandescent load, the useful dimming range is expected to be about 2 - 8ms. If the indicator display 14 14’ of the indicator IΓ is, for example, a 10 LED bar graph display, the corresponding indication of the level of the AC conducted to the incandescent load would range from 2 to 8 of the LEDs. In an example of an LED Bulb load, the useful dimming range is expected to be about 1 -7ms. If the indicator display 14 14’ of the indicator I Γ is again a 10 LED bar graph display, the corresponding indication of the level of the AC conducted to the incandescent load would range from 1 to 7 of the LEDs in the LED bar graph. In an example of a fan load, the useful dimming range is expected to be about 3 - 9ms. If the indicator display 14 14’ of the indicator IΓ is again a 10 LED bar graph display, the corresponding indication of the level of the AC conducted to the incandescent load would range from 3 to 9 of the LEDs in the LED bar graph.

[0031] In the above examples, the indicator I Γ indicates the half-cycle conduction period of the load as determinable by the user interface 20 20’ of the dimmer Si Sr. It will be appreciated by those persons skilled in the art, however, that it would be 2017201031 16 Feb 2017 9 possible for the indicator I Γ to incorporate a minimum and maximum offset facility so that all the LEDs in say the 10 LED bar graph operate over the useful dimming ranges for the different load types. That is, in the fan load example, the 10-LED bar graph indicator could be configured to illuminate 1 -10 of the LEDs corresponding to different levels of the load conduction angle range of 3 to 9ms.

[0032] In the embodiments of the dimming system 10’ with the indicator Γ being integral with the dimmer S-ι’ as shown in Figure 5, the indicator drive circuit is also implemented by the controller 16’ of the dimmer circuit 1T.

[0033] A person skilled in the art will appreciate that at least parts of the control of the indicator I Γ can be embodied in program code for implementation on a microprocessor. The program code could be supplied in a number of ways, such as on a memory of the indicator I Γ in data communication with the microprocessor, and could be configured to be implemented by the microprocessor implementing at least parts of the indicator controller 12 12’.

[0034] It will also be understood that there may be other variations and modifications to the configurations described herein that are also within the scope of the present invention.

[0035] The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing context for the present invention. It is not suggested or represented that any of these matters formed part of the prior art base or were common general knowledge as it existed before the priority date of each claim of this application.

Claims (11)

1. The claims defining the invention are as follows

   1. An indicator for a dimming system for controlling a load, the dimming system including at least one dimmer connected in series with the load and an alternating current (AC) source, wherein the at least one dimmer has a user interface and a dimmer circuit for controlling AC to the load, and wherein the dimmer circuit includes: an AC switch for switching the AC to the load at a conduction angle to control the load, wherein the indicator includes: an indicator controller configured to determine a duty cycle of a zerocrossing signal of the AC to the load in response to user input of the user interface selecting the conduction angle to control the load; and an indicator display for displaying an indication of a level of the AC conducted to the load based on the duty cycle.
2. 2. An indicator as claimed in claim 1, wherein the indicator is connected in parallel with the at least one dimmer.
3. 3. An indicator as claimed in claim 2, wherein the indicator controller includes a zero-crossing detection circuit configured to detect a zero-crossing of the AC to the load so as to generate the zero-crossing signal.
4. 4. An indicator as claimed in claim 2 or 3, wherein the indicator controller includes a power supply circuit configured to provide power for the indicator when the AC is not conducted to the load.
5. 5. An indicator as claimed in claim 1, wherein the dimmer circuit includes a controller including a zero-crossing detection circuit configured to detect a zero-crossing of the AC to the load so as to generate the zero-crossing signal.
6. 6. An indicator as claimed in any one of claims 1 to 5, wherein the indicator controller includes an indicator drive circuit configured to drive the indicator display to display the level of the AC conducted to the load according to a drive level based on the duty cycle of the zero-crossing signal.
7. 7. An indicator as claimed in claim 6, wherein the indicator drive circuit is configured to determine the drive level by converting the duty cycle to an analogue drive signal.
8. 8. An indicator as claimed in claim 7, wherein the indicator display is an analogue display.
9. 9. An indicator as claimed in claim 6, wherein the indicator drive circuit is configured to determine the drive level by measuring the duty cycle signal.
10. 10. An indicator as claimed in any one of claims 1 to 8, wherein the indicator display is an LED display.
11. 11. An indicator as claimed in claim 6, wherein the LED display is an LED graph display including a plurality of LEDs indicating the level of the AC conducted to the load.