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US 6,603,726 B1Granted
Pre-pit detection unit
AssigneePioneer Corporation
InventorsMasayoshi Yoshida, Yoshitaka Shimoda
Life of this patent
Estimating the term…
Abstract
A pre-pit detection unit having pre-pit detection circuits (600 and 700) respectively corresponding to beam intensity in mark and space periods that are provided in parallel on the output side of a push-pull circuit (500) for generating a pre-data signal. The pre-pit detection unit finally outputs the OR of the outputs of both pre-pit detection circuits as a pre-pit detection signal (l). An AGC circuit (601 and 701) for making the maximum amplitude of a radial push-pull signal (d) obtainable from said push-pull circuit coincide with a reference value is provided in the preceding stages of pre-pit detecting comparators (606 and 706) in the respective pre-pit detection circuits.
Claims18
A pre-pit detection unit comprising:
- a push-pull circuit for generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element,
- a first pre-pit detection circuit for beam intensity in a mark period for detecting a pre-pit corresponding to the beam intensity in the mark period according to the radial push-pull signal obtained from said push-pull circuit, and
- a second pre-pit detection circuit for beam intensity in a space period for detecting a pre-pit corresponding to the beam intensity in the space period according to the radial push-pull signal obtained from said push-pull circuit, so that the OR of outputs of both pre-pit detection circuits is outputted as a pre-pit detection signal, wherein
- a first and a second AGC circuits for making the maximum amplitude of said radial push-pull signal obtainable from said push-pull circuit coincide with a reference value are provided in the preceding stages of pre-pit detecting comparators in said first and said second pre-pit detection circuits respectively.
1 more element
A pre-pit detection unit comprising:
- a push-pull circuit for generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element, and
- a pre-pit detection circuit for detecting a pre-pit detection signal according to said radial push-pull signal, wherein
- said push-pull circuit includes:
- first and second AGC circuits for making the maximum amplitude of said each of lateral outputs obtained from said light receiving element coincide with a first reference value are provided in each input system of a differential operator forming said push-pull circuit for generating the pre-data signal, and
- said pre-pit detection circuit includes:
- a third ACiC circuit for making the maximum amplitude of said radial push-pull signal coincide with a second reference value,
- a comparator for comparing an output signal of said third AGC circuit with a predetermined threshold value.
4 more elements
A pre-pit detection unit comprising:
- a push-pull circuit for generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element, and
- a pre-pit detection circuit for detecting a pre-pit detection signal according to said radial push-pull signal, wherein
- said pre-pit detection circuit includes;
- an AGC circuit for making the maximum amplitude of said radial push-pull signal coincide with a reference value,
- a comparator for comparing an output signal of said AGC circuit with a predetermined threshold value, and
- said AGC circuit includes;
- a variable gain amplifier for adjusting the amplitude of the radial push-pull signal,
- an amplitude detector for detecting the amplitude of the output signal of said variable gain amplifier, and
- a differential operator circuit for generating a gain control signal for controlling the gain of said variable gain amplifier according to the output value of said amplitude detector and a predetermined reference value, and
- said amplitude detector includes;
- a first peak hold circuit which is positioned at the preceding stage and has a small time constant, and
- a second peak hold circuit which is positioned at the following stage and has a large time constant.
9 more elements
A pre-pit detection method comprising the steps of:
- generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element by a push-pull circuit,
- detecting a pre-pit corresponding to beam intensity in a mark period according to the radial push-pull signal obtained from said push-pull circuit by a first pre-pit detection circuit for the beam intensity in the mark period for, and
- detecting a pre-pit corresponding to a beam intensity in a space period according to the radial push-pull signal obtained from said push-pull circuit by a second pre-pit detection circuit for the beam intensity in the space period, so that the OR of outputs of both pre-pit detection circuits is outputted as a pre-pit detection signal, and
- making the maximum amplitude of said radial push-pull signal obtainable from said push-pull circuit coincide with a reference value by a first and a second AGC circuits provided in the preceding stages of pre-pit detecting comparators in said first and said second pre-pit detection circuits respectively.
1 more element
A pre-pit detection method comprising the steps of:
- generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element by a push-pull circuit,
- detecting a pre-pit detection signal according to said radial push-pull signal by a pre-pit detection circuit, and
- making the maximum amplitude of said each of lateral outputs obtained from said light receiving element coincide with a first reference value by first and second AGC circuits provided in each input system of a differential operator forming said push-pull circuit for generating the pre-data signal, wherein
- in said pre-pit detection circuit:
- making the maximum amplitude of said radial push-pull signal coincide with a reference value by a third AGC circuit,
- comparing an output signal of said third AGC circuit with a predetermined threshold value by a comparator.
3 more elements
A pre-pit detection method comprising the steps of:
- generating a radial push-pull signal including a pre-data signal according to each of lateral outputs of a light receiving element by a push-pull circuit,
- detecting a pre-pit detection signal according to said radial push-pull signal by a pre-pit detection circuit, wherein
- in said pre-pit detection circuit;
- making the maximum amplitude of said radial push-pull signal coincide with a reference value by an AGC circuit,
- comparing an output signal of said AGC circuit with a predetermined threshold value by a comparator, and
- in said AGC circuit;
- adjusting the amplitude of the radial push-pull signal by a variable gain amplifier, detecting the amplitude of the output signal of said variable gain amplifier by an amplitude detector, and
- generating a gain control signal for controlling the gain of said variable gain amplifier according to the output value of said amplitude detector and a predetermined reference value by a differential operator circuit, wherein
- said amplitude detector includes;
- a first peak hold circuit which is positioned at the preceding stage and has a small time constant, and
- a second peak hold circuit which is positioned at the following stage and has a large time constant.
8 more elements
Dependencies are inferred from the claim text.