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US 6,285,636 B1Granted
Optical disc apparatus with lens position detection and control
AssigneeTexas Instruments Incorporated
InventorsHiok-Nam Tay, Xiuli Guo
Life of this patent
Estimating the term…
Abstract
A method of generating a lens position detection signal for optical disc apparatus. The signal is generated in a way which provides continuous position information. The signal is also independent of changes in reflectivity on the surface of the optical disc. Moreover, the signal can be calibrated for DC offset due to misalignment and changes in photo-detector output.
Claims29
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- and
- performing fine lens position control in accordance with the difference of said envelope signals,
- wherein said photo-detector array is divided into quadrants, and signals from only one quadrant in each half of said photo-detector array parallel to said track direction are used to calculate said envelope signals.
2 more elements
A DVD-ROM drive system, comprising:
- (d.) an optical disc apparatus;
- (e.) a lens positioning mechanism;
- and
- (f.) lens position detection control, comprising:
- a photo-detector array divided in half parallel to the track direction of an optical disc apparatus which generates a pair of photo-detector signals, one from each half of said photo-detector array;
- envelope detection circuits which are each connected to a different one of said photo-detector signals and generate an envelope detection signal for each photo-detector signal;
- and
- an arithmetic circuit connected to subtract said envelope signal from the bottom half of said photo-detector array from said envelope signal from the top half of said photo-detector to produce a center error signal and drive said lens positioning mechanism accordingly,
- wherein said lens position detection control further comprises an analog-to-digital converter and a digital signal processor, wherein said envelope signals are connected to and quantized by said analog-to-digital converter, and said digital signal processor is connected to receive the output of said analog-to-digital converter, and the function of said arithmetic circuit is performed in said digital signal processor.
6 more elements
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- performing fine lens position control in accordance with the difference of said envelope signals;
- and
- correcting a shift of said envelope signal by using a digital processor.
2 more elements
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- performing fine lens position control in accordance with the difference of said envelope signals, and
- calculating a lens position detection signal to perform a fine lens position control in according with the differences of said envelope signals.
1 more element
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- and
- performing fine lens position control in accordance with the difference of said envelope signals,
- wherein said envelope signals are quantized and passed to a digital processer and said difference of said envelope signals as obtained by a subtracting and dividing operations performed in said digital processor.
2 more elements
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- and
- performing fine lens position control in accordance with the difference of said envelope signals,
- wherein an automatic gain control device is used to normalize a sum of said envelope signals for compensating for reflectivity changes in the photo-detector signals.
2 more elements
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- performing fine lens position control in accordance with the difference of said envelope signals, and
- performs calculating a lens position detection signal to perform a fine lens position control in according with the differences of said envelope signals.
1 more element
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- performing fine lens position control in accordance with the difference of said envelope signals, and
- calculating a lens position detection signal to perform a fine lens position control in according with the differences of said envelope signals.
1 more element
A method of fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a pair of photo-detector signals corresponding to radially separated disc locations;
- for each said signal received, calculating a respective envelope signal;
- and
- performing fine lens position control in accordance with the difference of said envelope signals,
- wherein said lens position detection signal is first calculated with zero input of a radial actuator to obtain a center error offset, and a gain is calculated as the slope of said lens position detection signal at 0 when the radial actuator bias is swept through a positive and negative range, and said center offset is subtracted from each successive calculation of said lens position detection signal, and said lens position detection signal is adjusted according to said gain.
2 more elements
A method of lens position detection signal calculation for fine control of lens position of an optical disc apparatus, comprising the steps of:
- receiving a photo-detector signal, from each of four or more divisions of a photo-detector array;
- for each said signal received, calculating an envelope signal;
- subtracting the sum of said envelope signals of said photo-detectors in the bottom half of said photo-detector array respective to a division parallel to the track direction of said optical disc apparatus from the sum of said envelope signals in the top half of said photo-detector array respective to a division parallel to said track direction of said optical disc apparatus to obtain a result;
- and
- dividing the result obtained by the sum of all said envelope signals to calculate said lens position detection signal.
2 more elements
A method of producing a lens position detection signal for fine control of an optical disc apparatus, comprising the steps of:
- (a.) receiving a pair of photo-detector signals, one from each part of a photo-detector array divided in half parallel to the track direction of said optical disc apparatus;
- (b.) for each said signal received, calculating an envelope signal;
- (c.) subtracting said envelope signal of said photo-detector below said division from said envelope signal of said photo-detector above said division to obtain a result;
- and
- (d.) dividing the result obtained in step (c.) by the sum of said envelope signals;
- (e.) performing steps (a.)-(d.) with zero input of a radial actuator to calculate an offset;
- (f.) calculating a gain by sweeping the input bias of said radial actuator of said optical disc apparatus through a positive and negative range and determining the slope of the result of step (d.) when said input bias is 0;
- (g.) performing steps (a.)-(d.) to calculate a center error;
- (h.) subtracting said offset from said center error;
- and
- (i.) adjusting the result obtained in accordance with said gain to produce said lens position detection signal.
8 more elements
A system of producing a lens position detection signal for fine control of lens position of an optical disc apparatus, comprising:
- a circuit for receiving a photo-detector signal from each division of a photo-detector array divided in half parallel to the track direction of an optical disc apparatus;
- a circuit for calculating an envelope detection signal for each photo-detector signal received;
- a circuit for subtracting said envelope signal from the bottom half of said photo-detector array respective to a division parallel to said track direction from said envelope detection signal from the top half of said photo-detector array respective to a division parallel to said track direction;
- and
- a circuit for dividing the result obtained by the sum of all said envelope signals to calculate said lens position detection signal,
- wherein said photo-detector array is divided into four or more divisions and generates signals from an equal number of divisions in each half of said photo-detector array parallel to said track direction.
3 more elements
A system of producing a lens position detection signal for fine control of lens position of an optical disc apparatus, comprising:
- a circuit for receiving a photo-detector signal from each division of a photo-detector array divided in half parallel to the track direction of an optical disc apparatus;
- a circuit for calculating an envelope detection signal for each photo-detector signal received;
- a circuit for subtracting said envelope signal from the bottom half of said photo-detector array respective to a division parallel to said track direction from said envelope detection signal from the top half of said photo-detector array respective to a division parallel to said track direction;
- a circuit for dividing the result obtained by the sum of all said envelope signals to calculate said lens position detection signal;
- and
- a circuit for correcting shift of said envelope detection signal.
3 more elements
A system of producing a lens position detection signal for fine control of lens position of an optical disc apparatus, comprising:
- a circuit for receiving a photo-detector signal from each division of a photo-detector array divided in half parallel to the track direction of an optical disc apparatus;
- a circuit for calculating an envelope detection signal for each photo-detector signal received;
- a circuit for subtracting said envelope signal from the bottom half of said photo-detector array respective to a division parallel to said track direction from said envelope detection signal from the top half of said photo-detector array respective to a division parallel to said track direction;
- a circuit for dividing the result obtained by the sum of all said envelope signals to calculate said lens position detection signal;
- and
- a circuit for calculating a center error offset and means for calculating a center error gain and means for correcting said lens position detection signal according to said center error offset and center error gain values.
3 more elements
A DVD-ROM drive system, comprising:
- (a.) an optical disc apparatus;
- (b.) a lens positioning mechanism;
- and
- (c.) lens position detection control, comprising:
- a photo-detector array divided in half parallel to the track direction of an optical disc apparatus which generates a pair of photo-detector signals, one from each half of said photo-detector array;
- envelope detection circuits which are each connected to a different one of said photo-detector signals and generate an envelope detection signal for each photo-detector signal;
- and
- an arithmetic circuit connected to subtract said envelope signal from the bottom half of said photo-detector array from said envelope signal from the top half of said photo-detector to produce a center error signal and drive said lens positioning mechanism accordingly,
- wherein said lens position detection control further comprises an analog-to-digital converter and a digital signal processor, wherein the digital signal processor is used to correct the envelope signal shift of the output of said arithmetic circuit.
6 more elements
Dependencies are inferred from the claim text.