WO2019148163A1

WO2019148163A1 - Dimmer

Info

Publication number: WO2019148163A1
Application number: PCT/US2019/015560
Authority: WO
Inventors: Zdenko Grajcar; David Natarelli; Peter Stolt; Hoa Huynh
Original assignee: Once Innovations Inc
Current assignee: Signify North America Corp
Priority date: 2018-01-29
Filing date: 2019-01-29
Publication date: 2019-08-01
Anticipated expiration: 2020-07-29

Abstract

Providing precisely timed pulses to lighting elements based on a desired dimming input, an optimum operating performance voltage of the lighting elements, a peak voltage of an alternating current (AC) power source, and the frequency of the AC power source. The peak voltage and frequency of the AC power source can be measured or determined such that the timing of current pulses to the lighting elements are calculated and provided to the lighting elements in response to variances in voltage or frequency of the AC power source from their nominal values, while operating the LEDs at a specific or optimal voltage level, thereby reducing the possibility of flicker, while also controlling the intensity of light output from lighting elements having one or more light emitting diodes. One or more current pulses of a calculated duration can be provided to the lighting elements during each cycle of the AC power source.

Description

DIMMER

CLAIM OF PRIORITY

This patent application claims the benefit of priority of Zdenko Grajcar, U.S Provisional Patent Application Serial Number 62/623,084, entitled“DIMMER,” filed on January 29, 2018 (Attorney Docket No. 3931.054PRV), which is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

This document pertains generally, but not by way of limitation, to artificial illumination.

BACKGROUND

The transition from incandescent lighting to other more efficient lighting technologies provides various challenges. Specifically, providing mechanisms to dim lighting elements, such as light emitting diode (LED) lamps, and reducing flicker that may be perceptible to humans. Examples of LED control circuits are presented m U.S. Patent no. 8,373,363 to Grajcar, and U.S. Patent no. 9,775,212 to Grajcar, each of which are incorporated by reference herein. SUMMARY

The present inventors have recognized, among other things, that a problem to be solved can include providing dimmable lighting elements that appear to the human eye to provide steady, e.g., flicker free, light despite variances in voltage or frequency from the nominal values of an input current. The present subject matter can help provide a solution to this problem, such as by providing precisely timed pulses to lighting elements based on a desired dimming input, an optimum operating performance voltage of a lamp or LED, a peak voltage of an alternating current (AC) power source, and the frequency of the AC pow¾r source. The peak voltage and frequency of the AC power source can be periodically measured or determined such that the timing of current pulses to the lighting elements can be adjusted to respond to variances in voltage or frequency from their nominal values, while operating the LEDs at a specific or optimal voltage level, thereby reducing the possibility of flicker being perceived by a human eye and also controlling the intensity of light output from a lighting element having one or more LEDs. These same dimming methodologies can be used to minimize spiking and ringing affects in both individual LED lamps as well as strings or lighting arrays that include multiple LED lamps.

This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 depicts a block diagram of a dimming circuit.

FIG. 2 depicts an example full-rectified sin-wave AC input with different peak voltages and two different on-cycles providing different intensities.

FIG. 3 depicts an example dimming method.

FIG. 4 depicts an example full-rectified sin-wave AC input with different peak voltages and two on-cycles providing a single intensity. DESCRIPTION

FIG. 1 depicts a block diagram of a dimming circuit 100. Dimming circuit

100 receives an alternating current 101 that provides a sinusoidal input, such as a 120 volt (V) at 60 Hz nominal input or a 230 volt at 50 Hz nominal input. Other voltage and frequency combinations can also be accommodated by techniques described herein. The sinusoidal input can optionally be filtered by an AC line filter 102. The AC line filter 102 can include a combination of inductors, capacitors, and resistors configured to filter or suppress undesired noise from the alternating current

101 such as electromagnetic interference (EMI), radio frequency interference (RFI), or a combination of EMI and REI.

The sinusoidal input from the alternating current 101 can be rectified by a full-wave rectifier 103 to generate an input with double the nominal frequency that periodically oscillates between zero volts and its nominal voltage. A voltage detector 104 measures a peak voltage of the input, e.g., 120 volts or 230 volts nominal. The peak voltage can also be calculated or determined based on an indirect measurement. The peak voltage of a source AC input may vary during operation due to changing loads or power fluctuations. It is desirable to adapt the behavior of the dimming circuit 100 to react to variances in the peak voltage in order to minimize the perception of flicker. The voltage detector 104 can include a RC circuit that provides a valise to an analog-to-digital input of the controller 114. The peak voltage is received and monitored by the controller 114 periodically or continuously. In an example, the controller can measure every peak cycle of the input alternating current 101. Less frequent measurement can also be performed by the controller 114.

A frequency detector 106 measures the frequency of the AC input 101. Both the detected peak voltage value of the AC input 101 and the measured frequency value of the AC input 101 are provided to a controller 114. In an example, the frequency detector 106 can be a part of the controller 114. For example, an analog to digital converter of the controller 114 can measure the period of one cycle of the AC input 101 to determine the frequency value. This measurement can be performed multiple times to determine an average frequency valise in one example, the frequency measurement can be performed only when the controller 114 is powered on or reset. In another example, the frequency measurement can be performed periodically when the controller 114 is m operation or when a change m the voltage of the AC input 101 is detected.

A dimmer input 116 can be supplied to the controller 114. The dimmer input 116 can include a manual switch or rheostat, or be a network input that is received over a wired or wireless network interface 124. In an example, the controller 114 can receive a dimming intensity value as a percentage of a maximum illumination output with a range from zero to one-hundred; zero indicating no illumination is desired and one-hundred indicating a maximum illumination is desired. In an example, the controller 114 can receive a control signal ranging from 0 volts (V) to 10V from the dimmer input 116; a 0V control signal indicating no illumination is desired, a 10V control signal radicating a maximum desired illumination, and any control signal voltage between 0V and 10V corresponding to a proportional intermediate intensity.

The controller 114 can be coupled to, or include, a memory 108, which can include volatile or non-volatile memory components. The memory 108 can include instructions 110 that are read and executed by the controller 114. In an example, the controller 114 can be a microprocessor, a microcontroller, a FPGA or a customized ASIC that includes the memory 108 or communicates with the memory 108 over a bus or link.

The memory 108, or a second separate memory device not depicted, can include one or more lighting element profiles 112. The one or more lighting element profiles 112 can include an array of values that correspond to a desired output intensity level for a specified lamp or LED type. The lighting element profiles 112 and the array of values can be stored in an array, table, database or other data structure suitable for storage in the memory 108. The lighting element profiles 112 can include optimum performance voltage values for a specified lamp or LED type for each different nominal voltage and frequency combination (e.g., 120 volts at 60 Hz or 230 volts at 50 Hz). For example, an optimal voltage level for a first LED in a lighting element may be 80 volts, and an optimal voltage level for a second LED in the lighting element may be 90 volts. The optimal voltage level or levels for individual LED types, stored in an array or other data format in memory 108, can include operating values or ranges that include stable voltages or voltage ranges where the light output from an LED type is stable or steady, and exclude voltages that would induce instability or flicker in a LED.

During operation, the controller 114 calculates a time it takes for the input voltage to increase from 0V to a trigger voltage. In an example, 40V is a trigger voltage value sensed by the threshold voltage detector 120 that prompts the controller 114 to start a lighting ON’ cycle. Other voltages, such as 30V or 50V, can be selected if longer or shorter time periods are desired. An ARCSIN value is calculated based on the measured input peak voltage level. Using the ARCSIN value the controller 114 calculates a trigger time (tTrig) to the trigger voltage value.

After tTrig is determined, the controller 114 selects an on-pulse time duration based on the desired output intensity level, and the nominal input voltage and frequency, from the lighting element profile 112 that corresponds to a LED or lamp type included in a lighting element 122. The lighting element 122 is coupled to the controller 114 by a driving circuit 118. The driving circuit 118 can include circuit elements to provide current to a first LED bank 126 and optional additional LED bank(s) 128.

The controller 114 calculates an initial delay tune (tDelay) based on the input peak voltage level so that the first on-pulse will start at a correct voltage level for the lighting element 122. For example, a correct voltage level for a specific LED in a lighting element may be 87 volts. Other LED or lamp types may operate optimally at lower or higher voltages between the threshold voltage and the nominal peak voltage. At high intensity level, the tDelay time can be a short fixed-delay to ensure a maximum light output from the lighting element 122 Using the desired output intensity level the controller 114 determines one or more pulse-on start time(s). The input frequency measurements and the on and off times for all pulses in a desired on-cycle are calculated and stored by the controller 114 along with the tTrig and tDelay time values. These stored values can then be used by the controller to repeatedly illuminate connected lighting elements as the AC input 101 cycles between zero volts and the peak voltage.

In an example, two on-pulses of the same pulse-on time length are timed to be symmetric about successive wave peaks of the AC input 101 In this example, two pulse-on times during the wave peak occur during an on-cycle when the input voltage is above a threshold voltage. In another example, the output of lighting elements can be increased in intensity by adding a third on-pulse in addition to the two symmetric on-pulses. The third on-pulse can be between the two symmetric on- pulses or at any other time during the on cycle. In another example, only a single on-pulse, during the AC wave peak, can be selected to provide a lower light intensity output. After all of the timings have been calculated the controller 114 waits until the input voltage rises to the trigger voltage, and then starts the on-cycle. During the on-cycle the controller 114 sends the on-pulses to the driving circuit 118 that illuminate the one or more lighting element(s) 122. The lighting element(s) 122 can include individual LEDs, an array of multiple LEDs such as a first LED bank 126, or multiple arrays of LEDs such as the first LED bank 126 and optional additional LED bank(s) 128 (e.g., a second LED bank or a plurality of LED banks).

By periodically or continuously measuring the input peak voltage and recalculating the timings before every on-cycle or pulse-on time the dimming circuit 100 compensates for fluctuations in the input peak voltage. This provides a consistent light output from the lighting elements 122 at low⁷, intermediate, and high intensity levels. Additionally, a smooth flicker free transition can be achieved, for example with multi-stage lamps that include multiple LEDs, as the output transitions from lower to higher intensities, and from higher to low⁷er intensities. For example, as the output transitions from a low intensity where only the first LED bank 126 is illuminated, to a higher intensity output where both the first LED bank 126 and the optional additional LED bank(s) 128 are illuminated an additional on- pulse may be provided by the controller 114 at a voltage that causes the optional additional LED bank(s) 128 to begin emitting light without flicker.

FIG. 2 depicts an example full-rectified sin-wave AC input 200 that cycles from zero volts to a nominal voltage peak (vPeak). A trigger voltage of 40 V is illustrated to show the corresponding tTrig time after the AC input begins to rise over zero volts. tTrig defines a time period before the beginning of an on-cycle, for example as the input voltage rises from zero volts to a threshold voltage. The passage of a tTrig time can indicate the beginning of an on-cycle period or cycle- start. time. During an on-cycle, after the threshold voltage is reached, one or more pulse-on times can be triggered after a delay time period (tDelay) elapses. The tTrig and tDelay times, along with the on-pulse duration(s) can be used to calculate the entire time period of the on-cycle. Based on the time period of the on-cycle two pulse-on times can be symmetrically triggered around the peak voltage, such that the on-pulses provide a specific desired voltage, between the threshold voltage and the peak voltage, to the lighting elements.

FIG. 2 also depicts an example of the full-rectified sin-wave AC input at a second voltage (vPeak2) that is higher than the nominal voltage peak (vPeak). A second on-cycle with three pulse-on tunes is depicted at the second voltage vPeak2. The three on-pulses provide a higher intensity illumination output from a lamp receiving the AC input than the same lamp receiving the first two on-pulses at vPeak. In FIG. 2, the third on-pulse is centered between the first and last symmetrical on-pulses. In another example, the third on-pulse can be positioned at any point, corresponding to a higher desired voltage, between the first and last symmetrical on-pulses. In this example, an additional second bank of LEDs can be illuminated at the higher voltage to avoid causing the LEDs in the additional second bank of LEDs to flicker when the second LED bank comes on. In this manner the light output of both the first bank and any additional banks of LEDs can be illuminated with minimal flicker, thereby providing a consistent and continuous light output. FIG. 3 depicts an example dimming method 300. Initially, at 302, an AC input is received. At 304, a controller or processor measures the AC input frequency of the AC input. The measurement of the AC input frequency can be performed using an analog to digital converter of the controller or processor. The period of one cycle is measured by waiting for the input to reach a set trigger level, starting a timer, and then waiting for the input to reach that same trigger level to stop the timer. The input frequency measurement can be performed multiple times and then an average frequency is calculated for use in subsequent calculations and operation.

At 3Q6 a dimming input is received. The dimming input can, for example, be a voltage signal ranging from zero volts to ten volts, or some other appropriate range of voltages that can be interpreted by the controller or processor as a desired level of illumination. At 3Q8, the controller or processor determines a peak voltage of the AC input. The determination of the peak voltage can be performed by reading a stepped-down or compressed voltage signal and then calculating the actual peak voltage. In an alternate example, the measurement of the AC input at 304 and the determination of the peak voltage of the AC input at 308 can be performed together before or after the receipt of the dimming input at 306. In another example, the measurement of the AC input at 304 or the determination of the peak voltage of the AC input at 308 can be performed before every lighting on-cycle, as discussed above with respect to FIG. 2, during method 300.

After the initial measurements, at 310, the controller or processor determines a threshold on- voltage time based on the peak voltage and the frequency. The threshold on-voltage time can correspond to a specific threshold voltage, such as forty volts, which can be used as a trigger to the controller or processor to start a timer that can operate during an on-cycle.

At 312, the controller or processor determines if an on-pulse time is needed based on the dimming input. For example, a zero-dimming input, i.e., no light requested, would not call for an on-pulse. If the dimming input requests

illumination, then one or more on-pulse time or times occur during an on-cycle time. The on-cycle time can, for example, include one, two, three or more different on-pulses that, at 314, drive a lighting element during the on-cycle time after a threshold voltage is met. The on-pulses can drive the lighting element with a voltage that causes the lighting element to output a stable, e.g., without human perceptible flicker, illumination. The voltage can be obtained from an array or table stored in a memory that is coupled to the controller or processor. Specific voltages can be utilized, and stored in the memory, for different nominal AC voltage inputs and dimming inputs.

Meth od 300 can repeat, starting at 308, during each cycle of the AC input. In another example, method 300 can repeat, starting at 306, when a new dimming input is received. A new dimming input can be detected by monitoring an input signal for a change in voltage. The input signal can be filtered, for example, by performing a hysteresis analysis of the input signal voltage to prevent or limit unwanted changes in the lighting intensity that could be caused by noise in the input signal . In an example, method 300 can repeat, starting at 304, at periodic intervals or after a specified number of cycles of the AC input. By continuously measuring the input peak voltage and recalculating the timings before every on-cycle the dimming method compensates for fluctuations in the input peak voltage. This provides for a consistent light output at both high and low intensity levels.

FIG. 4 depicts an example full-rectified sin-wave AC input 400 with different peak voltages and two on-cycles providing a single intensity. The sm-wave AC input 400 that cycles from zero volts to a nominal voltage peak (\ Peak ;·. A trigger voltage of 40 V is illustrated to show the corresponding tTrig time after the AC input begins to rise over zero volts. tTrig defines a time period before the beginning of an on-cycle, for example as the input voltage rises from zero volts to a threshold voltage. The passage of a tTrig time can indicate the beginning of an on- cycle period or cycle-start time. During an on-cycle, after the threshold voltage is reached, one or more pulse-on times can be triggered after a delay time period (tDelay) elapses. The tTrig and tDeiay times, along with the on-pulse duration(s) can be used to calculate the entire time period of the on-cycle. Based on the time period of the on-cycle two pulse-on times can be symmetrically triggered around the peak voltage, such that the on-pulses provide a specific desired voltage, between the threshold voltage and the peak voltage, to the lighting elements.

FIG. 4 also depicts an example of the full-rectified sin-wave AC input 400 at a second voltage (vPeak2) that is higher than the nominal voltage peak (vPeak). A second on-cycle with two pulse-on times is depicted at the second voltage vPeak2. The two on-pulses provide the same intensity illumination output from a lamp receiving the AC input as the same lamp receiving the first two on-pulses at vPeak. In FIG. 4, the first and second symmetrical on-pulses are centered around the voltage peak (vPeak2) and can start after a different tTring2 time and a different tDelay2 that can be calculated in response to the change from vPeak to vPeak2. In this example, a bank of LEDs can be illuminated at the same voltage as the two on- pul es of the first on-cycle to avoid causing the LEDs flicker due to the change in the voltage peak (e.g , the difference between vPeak and vPeak 2). In this manner the light output of the bank or banks of LEDs can be illuminated with minimal flicker, thereby providing a consistent and continuous light output.

The above description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as“examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.

In this document, the terms“a” or“an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of“at least one” or“one or more.” In this document, the term“or” is used to refer to a nonexclusive or, such that“A or B” includes“A but not B,”“B but not A,” and“A and B,” unless otherwise indicated. In this document, the terms “including” and“in which” are used as the plain-English equivalents of the respective terms“comprising” and“wherein.” Also, m the following claims, the terms“including” and“comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms“first,”“second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Method examples described herein can be machine or computer- implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAJVIs), read only memories (ROMs), and the like.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description.

Claims

THE CLAIMED INVENTION IS:

1. A method of dimming a lighting element comprising:

receiving an input alternating current;

determining a peak voltage of the input alternating current;

receiving a dimming input;

determining a trigger time based on a trigger voltage of the input alternating current;

determining a cycle-start time based on the trigger time;

determining at least one pulse-on time after the cycle-start time based on the cycle-start time and the dimming input;

detecting the trigger voltage; and

illuminating the lighting element during the at least one pulse-on time.

2. The method of claim 1, comprising:

measuring a frequency of the input alternating current; and

determining the cycle-start time based on the trigger time and the frequency.

3. The method of claim 1 , comprising:

illuminating the lighting element during a first pulse-on time and a second pulse-on time.

4 The method of claim 3, comprising:

illuminating the lighting element during a third pulse-on time in response to the dimmmg input being a high dimming input.

5. The method of claim 4, comprising:

illuminating the lighting element during a fourth pulse-on time in response to the dimming input being a high dimming input.

6. The method of claim 1 , wherein determining the peak voltage of the input alternating current includes calculating the peak voltage of the input alternating current based on an indirect measurement.

7. The method of claim 4, comprising:

illuminating a second bank of LEDs in the lighting element during the third pulse-on time with a second voltage that is higher than a first voltage used during the first pulse-on time and the second pulse-on time to illuminate a first bank of LEDs in the lighting element.

8. The method of claim 1, wherein illuminating the lighting element during the at least one pulse-on time includes providing a voltage to the lighting element that induces a stable output to be emitted from the lighting element.

9. The method of claim 1, wherein the lighting element includes a light emitting diode (LED).

10. A dimming device comprising:

a controller;

a dimming input coupled to the controller, the dimming input providing a dimming value to the controller;

a frequency detector coupled to the controller, the frequency detector providing a frequency valise of an alternating current input to the controller;

a peak voltage detector coupled to the controller, the peak voltage detector providing a peak voltage value of the alternating current input to the controller; a driving circuit coupled to the controller; and

at least one lighting element coupled to the driving circuit;

wherein the frequency detector and the peak voltage detector receive the alternating current input; and wherein the controller calculates a cycle start time and determines a pulse-on time based on the dimming value, the peak voltage value, and the frequency value, such that the driving circuit illuminates the lighting element in response to a pulse- on signal from the controller corresponding to the pulse-on time by provided an optimum operating performance voltage to the lighting element corresponding to the dimming input.

11. The dimming device of claim 10, comprising:

a threshold voltage detector coupled to the controller; wherein the controller receives an indication from the threshold voltage detector that the input alternating current has exceeded a threshold voltage.

12. The dimming device of claim 10, wherein the controller determines the pulse-on time and a second pulse-on time that are symmetrical about the peak voltage value of the alternating current input.

13. The dimming device of claim 12, wherein the controller determines the pulse-on time and the second pulse-on time that are symmetrical about the peak voltage value of the alternating current input and correspond to the optimum operating performance voltage.

14. The dimming device of claim 10, wherein the lighting element is a LED.

15. The dimming device of claim 10, wherein the lighting element includes a first bank of LEDs and a second bank of LEDs.

16 The dimming device of claim 10, comprising:

a memory coupled to the controller, the memory including an array of voltage values, wherein the driving circuit utilizes at least one of the voltage values to illuminate the lighting element with the at least one voltage value and cause the lighting element to output stable illumination during the pulse-on signal.

17. The dimming device of claim 10, wherein the cycle-start time is based on the trigger time and the frequency.

18. A non-transitory computer-readable storage medium, storing instructions that when executed by a processor of a lighting system, cause the processor to perform operations including:

determining a peak voltage of an input alternating current;

receiving a dimming input;

determining a cycle-start time based on the trigger time;

detecting the trigger voltage; and

illuminating the lighting element during the at least one pulse-on time.

19. The non-transitory computer-readable storage medium of claim 18, w iere m the instructions cause the processor to perform operations including:

measuring a frequency of the input alternating current; and

determining the cycle-start time based on the trigger time and the frequency.

20. The non-transitory computer-readable storage medium of claim 18, where in the instructions cause the processor to perform operations including:

illuminating the lighting element during a first pulse-on time and a second pulse-on time that are symmetric with respect to a peak in the input alternating current.