# US 2013/0154515 A1 · Systems and methods of applying bleed circuits in led lamps

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- Number: US 2013/0154515 A1
- Document ID: US20130154515A1
- Status: Published application
- Kind: A1
- Application number: 13/717,191
- Filed: 2012-12-17
- Published: 2013-06-20
- Earliest claimed: 2011-12-16
- Assignees: TerraLUX, Inc.
- Inventors: Brian Brandt
- Web page: https://patentgrep.com/patent/US20130154515A1

## CPC

- H05B 45/10: Controlling the intensity of the light
- H05B 45/3575: by means of dummy loads or bleeder circuits, e.g. for dimmers
- Y02B 20/40: Control techniques providing energy savings, e.g. smart controller or presence detection
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A bleed circuit is applied to a transformer based on a bleed-on time and a bleed-off time determined by monitoring an output voltage waveform of the transformer.

## Claims

### Claim 1

A method of operating an LED system including an electronic transformer, the method comprising:
monitoring an output voltage waveform of the transformer;
starting a bleed-on timing cycle upon sensing a first voltage-waveform condition and ending the bleed-on timing cycle after the determined bleed-on time has elapsed;
starting a bleed-off timing cycle upon sensing a second voltage-waveform condition different from the first voltage-waveform condition, and ending the bleed-off timing cycle after the determined bleed-off time has elapsed; and
engaging a bleed circuit to the transformer based on a state of the bleed-on timing cycle and disengaging the bleed circuit from the transformer based on a state of the bleed-off timing cycle, the bleed circuit being engaged for a duration adequate to ensure a minimum load on the transformer sufficient to avoid cut-off throughout the output voltage waveform.

### Claim 2 (depends on 1)

The method of claim 1, wherein the state of the bleed-on timing cycle a start thereof and the state of the bleed-off timing cycle is an end thereof.

### Claim 3 (depends on 1)

The method of claim 1, wherein the bleed-on timing cycle starts when a trailing edge of the output voltage waveform falls below a predetermined threshold and ends when a subsequent trailing edge of the output voltage waveform falls below a predetermined minimum threshold.

### Claim 4 (depends on 1)

The method of claim 1, wherein the bleed-off timing cycle starts when a leading edge of the output voltage waveform begins to rise and ends when the leading edge of the output voltage waveform exceeds a predetermined maximum threshold.

### Claim 5 (depends on 3)

The method of claim 3, further comprising, for a current bleed-on timing cycle:
starting the current bleed-on timing cycle upon sensing that the trailing edge of the output voltage waveform falls below the predetermined threshold;
determining a time interval since the trailing edge of the output voltage waveform previously fell below the predetermined threshold; and
ending the current bleed-on timing cycle after the time interval has elapsed.

### Claim 6 (depends on 4)

The method of claim 4, further comprising:
(i) for an initial bleed-off timing cycle:
starting the bleed-off timing cycle upon sensing that the leading edge of the output voltage waveform has begun to rise;
ending the bleed-off timing cycle upon sensing that the leading edge of the output voltage waveform exceeds the predetermined maximum threshold; and
determining a time interval between the starting and ending of the bleed-off timing cycle; and
(ii) for a subsequent bleed-off timing cycle:
starting the bleed-off timing cycle upon sensing that the leading edge of the output voltage waveform has begun to rise; and
ending the bleed-off timing cycle after the time interval has elapsed.

### Claim 7 (depends on 5)

The method of claim 5, further comprising, for a plurality of subsequent bleed-on timing cycles, omitting the determining step and ending a subsequent bleed-on timing cycle after the time interval has elapsed.

### Claim 8 (depends on 6)

The method of claim 6, further comprising repeating step (ii) for a plurality of subsequent bleed-off timing cycles.

### Claim 9 (depends on 1)

The method of claim 1, wherein the bleed-on and bleed-off timing cycles are determined based on a period of the output voltage waveform.

### Claim 10 (depends on 9)

The method of claim 9, wherein the bleed-on timing cycle and the bleed-off timing cycle are adjusted until the period of the monitored output voltage waveform is equivalent to a predetermined period of the output voltage waveform generated by the transformer.

### Claim 11

A system for minimizing flicker in a circuit comprising an LED lamp and an electronic transformer, the system comprising:
a bleed circuit;
an analyzer for monitoring an output voltage waveform of the transformer and determining a bleed-on timing cycle and a bleed-off timing cycle based at least in part on the monitored output voltage waveform;
a memory for storing a duration of the bleed-on timing cycle and a duration of the bleed-off timing cycle; and
control circuitry for engaging the bleed circuit to the transformer during only a portion of a period of the output voltage waveform and based at least in part on the stored durations, the bleed circuit ensuring a minimum load on the transformer sufficient to avoid cut-off.

### Claim 12 (depends on 11)

The system of claim 11, wherein the bleed circuit comprises at least one of a resistor or a transistor.

### Claim 13 (depends on 11)

The system of claim 11, wherein the analyzer is configured to start a bleed-on timing cycle when a trailing edge of the output voltage waveform falls below a predetermined threshold and to end the bleed-on timing cycle when a subsequent trailing edge of the output voltage waveform falls below a predetermined minimum threshold.

### Claim 14 (depends on 13)

The system of claim 13, wherein the analyzer is configured to start a bleed-off timing cycle when a leading edge of the output voltage waveform begins to rise and to end the bleed-off timing cycle when the leading edge of the output voltage waveform exceeds a predetermined maximum threshold.

### Claim 15 (depends on 14)

The system of claim 14, wherein the control circuit is configured to engage the bleed circuit at a start of a bleed-on timing cycle and to disengage the bleed circuit at an end of a bleed-off timing cycle.