US 7,126,889 B2Granted

Tracking error detector

AssigneeTexas Instruments Incorporated

InventorsKoyu Yamanoi, Hironobu Murata, Aoe Takashi

Life of this patent

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Abstract

A circuit to improve the SN characteristic of a tracking error signal. This tracking error detection circuit is formed as a push-pull system utilizing a quadrant type photo-detector and provided with 4 gain control amplifiers 20, 22, 24, and 26, 4 bottom envelope circuits 28, 30, 32, and 34, a pair of subtracting circuits 36 and 38, adding (subtracting) circuit 40, offset circuit 42, and gain control circuit 44. Bottom envelope circuits 28, 30, 32, and 34 are configured with a capacitor-type peak-hold circuit, for example, whereby bottom envelopes of RF signals SA, SB, SC, and SD given from light receiving areas A, B, C, and D of a photo-detector via gain control amplifiers 20, 22, 24, and 26 are detected, and bottom envelope signals SAbtm, SBbtm, SCbtm, and SDbtm representing the waveforms of the respective bottom envelopes are output.

Claims4

Dependent claims

A tracking error detector being a tracking error detector for detecting a positional error in the radial direction perpendicular to the track direction of a beam spot on a recording plane of an optical disk as a tracking error, comprising:

a photo-detection circuit which receives a beam of light reflected by the signal recording plane of the optical disk using a first and a second set of light receiving areas provided in inverse phases and outputs multiple electric signals according to the light intensities of the light beam reflected at the light receiving areas of the respective sets,
bottom envelope detection circuit which detect bottom envelopes of the multiple electric signals and generate multiple bottom envelope signals representing the waveforms of the respective bottom envelopes,
a first adding circuit which takes the sum of the multiple bottom envelope signals obtained from the first set of light receiving areas in order to generate a first added signal,
a first adding circuit which takes the sum of the multiple bottom envelope signals obtained from the second set of light receiving areas in order to generate a second added signal, and
a tracking error generating circuit which takes the difference between the first added signal and the second added signal in order to generate a tracking error signal representing the tracking error.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/314,821Filed 9 Dec 2002
Priority: JP 2001-39590227 Dec 2001
Published: US 2004/0047250 A111 Mar 2004
Granted: 24 Oct 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G11B 7/131
Optical detectors therefor: arrangement of detectors in a multiple array
G11B 7/0901
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B 7/0903
For track following only: multi-beam tracking systems
G11B 7/0943
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…