| US 7,474,235 B2 | ||
| Automatic power control system for optical disc drive and method thereof | ||
| Bing-Yu Hsieh, Taipei (Taiwan); Ming-Jiou Yu, Taipei (Taiwan); Kuo-Jung Lan, Taipei County (Taiwan); Shu-Hung Chou, Taipei County (Taiwan); Chih-Ching Chen, Miaoli County (Taiwan); and Chia-Wei Liao, Hsinchu County (Taiwan) | ||
| Assigned to Mediatek Inc., Hsin-Chu (Taiwan) | ||
| Filed on Jun. 05, 2007, as Appl. No. 11/758,119. | ||
| Claims priority of provisional application 60/803874, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/803875, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/803887, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/810991, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/810972, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/810989, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/811031, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/811017, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/810990, filed on Jun. 05, 2006. | ||
| Claims priority of provisional application 60/810898, filed on Jun. 05, 2006. | ||
| Prior Publication US 2007/0279274 A1, Dec. 06, 2007 | ||
| Int. Cl. H03M 7/00 (2006.01) | ||
| U.S. Cl. 341—61 [375/354] | 7 Claims |
| 1. An automatic power control system for an optical disc drive to control the power of laser beam, the optical disc drive
comprising a laser diode for receiving a control signal to generate a laser beam; and a photodetector for detecting the laser
beam to generate an analog input signal; the automatic power control system, comprising:
an analog-to-digital converter, converting the analog input signal into digital data;
a down sampling circuit, coupled to the analog-to-digital converter, comprising:
a down sampler, receiving a predetermined amount of digital data to generate representation data;
a counter, coupled to the down sampler, calculating an amount of the digital data, and resetting the down sampler when the
amount equals or exceeds the predetermined count; and
a controller, coupled to the counter, disabling the counter when the digital data is invalid;
a comparator, coupled to the down sampling circuit, comparing the representation data with predetermined target data to generate
error data; and
a digital-to-analog converter, coupled to the comparator, converting the error data to analog to generate the control signal.
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