Apparatus and method for detecting beam power in optical drive

An optical recording device, comprising:

• a first light source to produce a first light beam at a first recording power level suitable to optically record to a first type of recording medium;
• a second light source to produce a second light beam at a second recording power level suitable to optically record to a second type of recording medium, the second recording power level being different from the first recording power level;
• a power level monitoring circuit to produce an amplified detection signal representing respective monitored output power levels of at least one of the first light beam and the second light beam, the power level monitoring circuit further comprising:
• a light receiving unit to receive, and to produce a proportional detection signal in response to, at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• and
• an amplification unit having at least a first gain and a second gain, the first gain and the second gain being different from each other, with the amplification unit being configured to receive the detection signal, and to selectively apply to the detection signal one of the first gain and the second gain, to produce the amplified detection signal, with the amplified detection signal having a first dynamic range when the first gain is applied to the detection signal resulting from detection of the portion of the first light beam, and with the amplified detection signal having a second dynamic range when the second gain is applied to the detection signal resulting from detection of the portion of the first light beam, with the first gain being predetermined such that the first dynamic range is wider than the second dynamic range;
• and
• an automatic power control unit to adjust an output power level of at least one of the first light source and the second light source based on the amplified detection signal to maintain the output power level of the first light source substantially at the first recording power level and the output power level of the second light source substantially at the second recording power level.

A recording and/or reproducing apparatus to record on or reproduce from an optical recording medium, comprising:

• a first light source to produce a first light beam at a first desired power level suitable to optically read from and/or record to a first type of recording medium;
• a second light source to produce a second light beam at a second desired power level suitable to optically read from and/or record to a second type of recording medium, with the second desired power level being different from the first desired power level;
• and
• a light detection circuit configured to produce an amplified detection signal representing detection of at least one of the first light beam and the second light beam, the light detection circuit comprising:
• a light receiving unit configured to receive at least one of at least a portion of the first light beam and at least a portion of the second light beam, and to produce a proportional detection signal in response to the received at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• and
• an amplification unit having at least a first gain and a second gain, the first gain and the second gain being different from each other, the amplification unit being configured to receive the detection signal, and to selectively apply to the detection signal one of the first gain and the second gain to produce the amplified detection signal, the amplification unit further comprising a first gain adjustment circuit to vary the first gain and a second gain adjustment circuit to vary the second gain.

A monitoring method of monitoring respective output levels of at least a first light source and a second light source in an optical recording device, the first light source producing a first light beam at a first recording power level suitable for optically recording to a first type of recording medium, the second light source producing a second light beam at a second recording power level suitable for optically recording to a second type of recording medium, with the first recording power level and the second recording power level being different from each other, the monitoring method comprising:

• predetermining a first gain suitable for use in monitoring the output level of the first light source;
• predetermining a second gain suitable for use in monitoring the output level of the second light source;
• determining which one of the first type of recording medium or the second recording medium is being recorded to;
• detecting at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• producing a detection signal proportional to the detected at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• and
• selectively applying one of the first or second gains to the detection signal to produce an amplified detection signal, the first gain being applied when it is determined that the first type recording medium is being recorded to, and the second gain being applied when it is determined that the second type of recording medium is being recorded to, the amplified detection signal having a first dynamic range when the first gain is applied to the detection signal resulting from detection of the portion of the first light beam and the amplified detection signal having a second dynamic range when the second gain is applied to the detection signal resulting from detection of the portion of the first light beam,
• wherein the first gain is predetermined such that the first dynamic range is wider than the second dynamic range.

A monitoring method of monitoring at least a first light source and a second light source in a device for recording to and/or reproducing from an optical recording medium, with the first light source being configured to produce a first light beam at a first desired power level suitable for optically recording to and/or reading from a first type of recording medium, the second light source being configured to produce a second light beam at a second desired power level suitable for optically recording to and/or reading from a second type of recording medium, the monitoring method comprising:

• providing a first predetermined gain suitable for use in detecting the first light beam;
• providing a second predetermined gain suitable for use in detecting the second light beam, the second predetermined gain being different from the first predetermined gain;
• providing a first variable gain adjustment unit to adjust the first predetermined gain to produce a first adjusted gain;
• providing a second variable gain adjustment unit to adjust the second predetermined gain to produce a second adjusted gain;
• determining which one of the first type of recording medium or the second type of recording medium is being recorded to and/or read from;
• detecting at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• producing a detection signal proportional to the detected at least one of at least a portion of the first light beam and at least a portion of the second light beam;
• and
• selectively applying one of the first adjusted gain and the second adjusted gain to the detection signal to produce an amplified detection signal, the first adjusted gain being applied when it is determined that the first type recording medium is being recorded to or read from, and the second gain being applied when it is determined that the second type of recording medium is being recorded to and/or read from.