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US 7,598,679 B2Granted
Integrated circuit capable of synchronization signal detection
AssigneeO2Micro International Limited
InventorsYung-Lin Lin, Yu-Cheng Chang
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Abstract
A method according to one embodiment may include providing power to at least one light source. The method of this embodiment may also include detecting the frequency of at least one vertical synchronization signal, among a plurality of different synchronization signals, and controlling the power to at least one light source based on, at least in part, the detected frequency of at least one vertical synchronization signal. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment.
Claims19
An apparatus, comprising:
- an integrated circuit configured to provide power to at least one light source, the integrated circuit further configured to receive a vertical synchronization signal, the integrated circuit comprising:
- synchronization detection circuitry configured to determine whether the frequency of said vertical synchronization signal complies with at least one of a Phase Alternating Line (PAL) or National Television System Committee (NTSC) vertical synchronization signal, said synchronization detection circuitry comprising:
- a current source and a capacitor configured to generate an internal reference signal,
- a switch configured to discharge said capacitor based on said vertical synchronization signal, and
- a comparator configured to compare said internal reference signal with a DC reference signal and generate a first signal if said internal reference signal is less than said DC reference signal and a second signal if the internal reference signal is greater than said DC reference signal;
- wherein said first signal is generated if said vertical synchronization signal changes state before said internal reference signal reaches said DC reference signal, and said second signal is generated if said vertical synchronization signal changes state after said internal reference signal reaches said DC reference signal,
- flip-flop circuitry configured to receive said first and second signals and generate first and second output signals, respectively;
- wherein said first output signal is indicative that said vertical synchronization signal is an NTSC vertical synchronization signal and said second output signal is indicative that said vertical synchronization signal is said PAL vertical synchronization signal;
- and
- pulse width modulation (PWM) circuitry configured to generate a PWM signal to adjust power to said light source, said PWM signal having a frequency that is based on the detected frequency of said vertical synchronization signal.
7 more elements
A system, comprising:
- a television display comprising at least one light source;
- and
- an integrated circuit configured to provide power to at least one light source, the integrated circuit further configured to receive a vertical synchronization signal, the integrated circuit comprising:
- synchronization detection circuitry configured to determine whether the frequency of said vertical synchronization signal complies with at least one of a Phase Alternating Line (PAL) or National Television System Committee (NTSC) vertical synchronization signal, said synchronization detection circuitry comprising:
- a current source and a capacitor configured to generate an internal reference signal,
- a switch configured to discharge said capacitor based on said vertical synchronization signal, and
- a comparator configured to compare said internal reference signal with a DC reference signal and generate a first signal if said internal reference signal is less than said DC reference signal and a second signal if the internal reference signal is greater than said DC reference signal;
- wherein said first signal is generated if said vertical synchronization signal changes state before said internal reference signal reaches said DC reference signal, and said second signal is generated if said vertical synchronization signal changes state after said internal reference signal reaches said DC reference signal,
- flip-flop circuitry configured to receive said first and second signals and generate first and second output signals, respectively;
- wherein said first output signal is indicative that said vertical synchronization signal is an NTSC vertical synchronization signal and said second output signal is indicative that said vertical synchronization signal is said PAL vertical synchronization signal;
- and
- pulse width modulation (PWM) circuitry configured to generate a PWM signal to adjust power to said light source, said PWM signal having a frequency that is based on the detected frequency of said vertical synchronization signal.
9 more elements
A method, comprising:
- providing power to at least one light source;
- receiving a vertical synchronization signal;
- determining if the frequency of said vertical synchronization signal complies with at least one of a Phase Alternating Line (PAL) or National Television System Committee (NTSC) vertical synchronization signal, said determining comprising:
- generating an internal reference signal,
- discharging said internal reference signal based on said vertical synchronization signal,
- comparing said internal reference signal with a DC reference signal, wherein a result of said comparison depends on the frequency of said vertical synchronization signal and generating a first signal if said internal reference signal is less than said DC reference signal and a second signal if the internal reference signal is greater than said DC reference signal;
- wherein said first signal is generated if said vertical synchronization signal changes state before said internal reference signal reaches said DC reference signal, and said second signal is generated if said vertical synchronization signal changes state after said internal reference signal reaches said DC reference signal,
- generating first and second output signals based on said first and second signals and, respectively;
- wherein said first output signal is indicative that said vertical synchronization signal is an NTSC vertical synchronization signal and said second output signal is indicative that said vertical synchronization signal is said PAL vertical synchronization signal;
- and
- generating a PWM signal to adjust power to said light source, said PWM signal having a frequency that is based on the detected frequency of said vertical synchronization signal.
8 more elements
Dependencies are inferred from the claim text.