Deep dimming of an LED-based illumination device
First Claim
1. A method of controlling an average current supplied to an LED based illumination device, comprising:
- receiving an indication of a desired average current level that differs from a first average current level supplied to a light emitting diode (LED) of the LED based illumination device;
generating a digital control signal with a comparator circuit for periodically switching a current supplied to the LED of the LED based illumination device from a high state to a low state over a switching period while generating an analog control signal with a digital to analog conversion circuit for adjusting a value of the current supplied to the LED during the high state, adjusting a duration of the switching period and adjusting a ratio of a time in the high state to a time in the low state by adjusting with the comparator circuit both the time in the high state and the time in the low state, as the average current supplied to the LED of the LED based illumination device transitions from the first average current level to the desired average current level; and
supplying the current to the LED of the LED based illumination device based on the analog control signal and the digital control signal.
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Accused Products
Abstract
An LED based illumination device is dimmed by controlling an average current supplied to the LED based illumination device. The currently supplied to the LED may be supplied by an LED driver that is in communication with a dimming control engine. The dimming control engine may receive an indication of a desired average current level. The dimming control engine controls the LED driver to periodically switch a current supplied to an LED of the LED based illumination device from a high state to a low state over a switching period, wherein both a duration of the switching period is adjusted and a ratio of a time in the high state to a time in the low state is adjusted as the average current supplied to the LED based illumination device transitions from a first average current level to the desired average current level.
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Citations
16 Claims
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1. A method of controlling an average current supplied to an LED based illumination device, comprising:
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receiving an indication of a desired average current level that differs from a first average current level supplied to a light emitting diode (LED) of the LED based illumination device; generating a digital control signal with a comparator circuit for periodically switching a current supplied to the LED of the LED based illumination device from a high state to a low state over a switching period while generating an analog control signal with a digital to analog conversion circuit for adjusting a value of the current supplied to the LED during the high state, adjusting a duration of the switching period and adjusting a ratio of a time in the high state to a time in the low state by adjusting with the comparator circuit both the time in the high state and the time in the low state, as the average current supplied to the LED of the LED based illumination device transitions from the first average current level to the desired average current level; and supplying the current to the LED of the LED based illumination device based on the analog control signal and the digital control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An LED based illumination device, comprising:
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at least one light emitting diode (LED); a LED driver coupled to the LED, the LED driver configured to supply a current to the LED based on an analog control signal and a digital control signal received by the LED driver; and a dimming control engine configured to communicate the analog control signal and the digital control signal to the LED driver, the dimming control engine, comprising; an amount of electronic circuitry comprising a comparator circuit configured to generate the digital control signal that causes the LED driver to periodically switch the current supplied to the LED between a high state and a low state over a switching period and a digital to analog converter configured to generate the analog control signal that causes the LED driver to change a value of the current supplied to the LED during the high state, and wherein both a duration of the switching period and a ratio of a time in the high state to a time in the low state are adjusted by the comparator circuit, wherein the ratio of the time in the high state and the time in the low state is adjusted by adjusting both the time in the high state and the time in the low state, as an average current supplied to the LED based illumination device transitions from a first average current level to a desired average current level. - View Dependent Claims (11, 12, 13)
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14. A dimming control engine, comprising:
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a microprocessor configured to receive an indication of a desired average current level supplied to a light emitting diode (LED) based illumination device; an amount of electronic circuitry comprising a comparator circuit configured to generate a digital control signal that periodically switches a current supplied to the LED based illumination device between a high state and a low state and a digital to analog converter configured to generate an analog control signal to cause a change in a value of the current supplied to the LED based illumination device during the high state, and wherein both a duration of a switching period and a ratio of a time in the high state to a time in the low state are adjusted by the comparator circuit, wherein the ratio of the time in the high state and the time in the low state is adjusted by adjusting both the time in the high state and the time in the low state, as an average current supplied to the LED based illumination device transitions from a first average current level to the desired average current level. - View Dependent Claims (15, 16)
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Specification