KR950012355A - Focus and Tracking Error Detection System for Magneto-optical Disk Drives - Google Patents

Abstract

The present invention relates to a focusing and tracking error detection system for an optical disc drive that is reflected from the surface of an optical disc of the light beam. The system directs a portion of the lens and the reflected light beam to direct the reflected light beam to the first point. And a prism positioned between the first point and the lens for switching.

The first photodetector is located at a first distance from the first point between the prism and the first point. The second optical detector is spaced apart from the second point facing the prism by the same first distance. The first photodetector has a first photosensitive region at its center and second and third photosensitive regions on both sides of the first photosensitive region. The second photodetector has a fourth photosensitive region at its center and has fifth and sixth photosensitive regions on both sides of the fourth photosensitive region. Circuits are connected to the first and second photodetectors. The circuit includes an adder for adding the outputs of the second and third photosensitive regions and the outputs of the fifth and sixth photosensitive regions, respectively, to form first and second addition signals. Also provided is an apparatus for forming first and second normal focus error signals by normalizing the first and second addition signals, respectively, with respect to the sum signal obtained from the three photosensitive regions of the first and second photodetectors.

Description

Focus and Tracking Error Detection System for Magneto-optical Disk Drives

Since this is an open matter, no full text was included.

1 is a schematic diagram of a magneto-optical disk drive system constructed in accordance with the principles of the present invention;

2A and 2B are plan views of the photodetectors in the magneto-optical disk drive system of FIG.

3 is a schematic diagram of circuitry in the magneto-optical disk drive system of FIG.

Claims (18)

A lens for directing the reflected light beam reflected from the information-bearing surface of the optical disc to the first point in the first direction and at a position capable of receiving at least a portion of the reflected light beam, the first distance from the first point in the first direction. A first photosensitive region in the center and second and third photosensitive regions on both sides of the first photosensitive region, each of the photosensitive regions forming an output proportional to the amount of light incident on the photosensitive region; Photodetectors; And a circuit connected to the first photodetector, the adder configured to add outputs of the second and third photosensitive regions to form a first addition signal; A comparison device for forming a first comparison signal by comparing the first addition signal with an output from the first photosensitive region; An adder configured to add outputs of the first, second and third photosensitive regions to form a first sum signal; and a divider to divide the first comparison signal into a first sum signal to form a first normal focus error signal A focus error detection system for an optical disc drive, comprising a circuit consisting of a light beam reflected from an information bearing surface of an optical disc of a light beam. 2. The optical sensing device of claim 1, wherein the first photosensitive region is composed of first and second photosensitive sub-regions, and the circuit compares the outputs of the first and second sub-regions to direct light beams in the radial direction of the optical disc. The system further comprises a comparator for forming a tracking error signal for alignment. The system of claim 1, wherein the optical disc is made of a magneto-optical disc and the reflected light beam is polarized. 2. The system of claim 1, wherein the focus error detection system comprises: a prism positioned between the lens and the first point to divert a portion of the reflected light beam toward the second point in a second direction; The first and second distances from the second point in the second direction, having a fourth photosensitive region and a fifth photosensitive region on both sides of the fourth photosensitive region, and each photosensitive region is a photosensitive region. A second photodetector forming an output proportional to the amount of incident light; And an adder configured to form a second addition signal by adding outputs of the fifth and sixth photosensitive regions; A comparison device for forming a second comparison signal by comparing the second addition signal with the output from the fourth photosensitive region; An adder which adds outputs of the fourth, fifth and sixth photosensitive regions to form a second sum signal; A dividing apparatus for dividing the second comparison signal into the second total signal to form a second normal focus error signal; And an adder configured to add the first and second regular focus error signals to form a combined focus error signal. 5. The system of claim 4, wherein the optical disc is comprised of a magneto-optical disc and the reflected light beam is polarized. A lens for directing the reflected light beam reflected from the information bearing surface of the optical disc to the first point in the first direction, and a first distance from the first point in the first direction at a position capable of receiving at least a portion of the reflected light beam Spaced apart, divided into three parallel regions including one central portion and two outer portions on both sides of the central portion, the central portion is further divided into first and second photosensitive tracking regions, and the outer portion is formed of the first and second portions. A first photodetector comprising two photosensitive focus regions, each photosensitive region configured to form an output proportional to an amount of light incident on the photosensitive region; And a circuit coupled to the first photodetector, the comparator for comparing outputs of the first and second photosensitive tracking regions to form a first comparison tracking signal, the first and second photosensitive tracking regions, and An adder that adds outputs of the first and second photosensitive focus regions to form a first sum signal; And a dividing device for dividing the first comparison tracking signal into the first total signal to form a first normal tracking error signal. 7. The apparatus of claim 6, wherein the circuit further comprises: an adder which adds outputs of the first and second photosensitive focus regions to form a first add focus signal; An adder for adding a first output of said first and second photosensitive tracking regions to form a first add tracking signal; A comparison device for forming a first comparison focus signal by comparing the first addition focus signal and the first addition tracking signal; And a dividing device for dividing the first comparison focus signal into the first sum signal to form a first normal focus error signal. 7. The system of claim 6, wherein the optical disc is comprised of a magneto-optical disc and the reflected light beam is polarized. 7. The system of claim 6, wherein the tracking error detection system comprises: a prism positioned between the lens and the first point to convert a portion of the reflected light beam to a second point; The center of the second point facing the prism is separated from the second point by the first distance, and divided into three parallel regions including two outer portions on both of one central portion and the central portion, the central portion Is again divided into third and fourth photosensitive tracking regions, and the outer portion is composed of third and fourth photosensitive focusing regions, each photosensitive region forming a second output that is proportional to the amount of light incident on the photosensitive region. Photodetectors; And a circuit, comprising: a comparator for comparing outputs of the third and fourth photosensitive tracking regions to form a second comparison tracking signal; An adder for adding a third and fourth photosensitive tracking area and an output of the third and fourth photosensitive focus area to form a second sum signal; A dividing apparatus dividing the second comparison tracking signal into the second total signal to form a second normal tracking error signal; And an adder configured to add the first and second regular tracking error signals to form a combined tracking error signal. 10. The apparatus of claim 9, wherein the circuit further comprises: an adder which adds outputs of the first and second photosensitive focus regions to form a first addition focus signal; An adder for adding a first output of said first and second photosensitive tracking regions to form a first addition tracking signal; A comparison device for forming a first comparison focus signal by comparing the first addition focus signal with the first addition tracking signal, and dividing the first comparison focus signal by the first sum signal to form a first normal focus error signal A divider; An adder for adding the output of the third and fourth photosensitive focus regions to form a second add focus signal, and an adder for adding the outputs of the third and fourth photosensitive tracking regions to form a second add tracking signal; A comparison device for forming a second comparison focus signal by comparing the second addition focus signal with the second addition tracking signal; A dividing apparatus dividing the second comparison focus signal into the second sum signal to form a second normal focus error signal; And an adder which adds the first and second normal focus error signals to form a combined focus error signal. 11. The system of claim 10, wherein the optical disk is comprised of a magneto-optical disk and the reflected light beam is polarized. Directing the reflected light beam reflected from the information bearing surface of the optical disc through the lens to the first point in the first direction; A first distance from the first point in the first direction at a location capable of receiving at least a portion of the light beam, the first and second photosensitive regions at both the first and second photosensitive regions in the center; Wherein each photosensitive region is a first photodetector configured to form an output proportional to the amount of light incident on the photosensitive region, the method comprising: detecting a portion of the light beam; Forming a first addition signal by adding outputs of the second and third photosensitive regions; Forming a first comparison signal by comparing the first addition signal with an output from the first photosensitive region; Forming a first sum signal by adding outputs of the first, second and third photosensitive regions; And dividing the first comparison signal into the first sum signal to form the first normal focus error signal, wherein the optical beam is reflected from the information inclusion surface of the optical disc. 13. The optical disc of claim 12, wherein the first photosensitive region includes first and second photosensitive sub-regions therein, and the method compares the output of the first and second sub-regions to form a tracking error signal. And a process of aligning the light beam in the radial direction of the focus error detection method. 13. The method of claim 12, further comprising: converting a portion of the reflected light beam to a second point in a second direction by a prism positioned between the lens and the first point; A fifth distance from the second point in the second direction by the first distance and having a fifth photosensitive region and a fifth photosensitive region on both sides of the fourth photosensitive region, and each photosensitive region is incident on the photosensitive region. A second photodetector for forming an output proportional to an amount of light to detect a portion of the converted light beam; Forming a second addition signal by adding outputs of the fifth and sixth photosensitive regions; Forming a second comparison signal by comparing the second addition signal with an output from the fourth photosensitive region; Forming a second total signal by adding outputs of the fourth, fifth and sixth photosensitive regions; Dividing the second comparison signal into the second total signal to form the second normal focus error signal; And forming a combined focus error signal by adding the first and second regular focus error signals. 15. The method of claim 14, wherein the first photosensitive region includes first and second photosensitive sub-regions therein, and the fourth photosensitive region includes third and fourth photosensitive sub-regions, the method comprising: Comparing the output of the second photosensitive sub-region to form a first comparison tracking signal; Forming the first summation signal by adding outputs of the first and second photosensitive sub-regions and the second and third photosensitive regions; Dividing the first comparison tracking signal into the first sum signal to form a first normal tracking error signal; Comparing the outputs of the third and fourth photosensitive sub-regions to form a second comparison tracking signal, and adding the outputs of the third and fourth photosensitive sub-regions and the fifth and sixth photosensitive sub-regions to add the second sum. Forming a signal; Dividing the second comparison tracking signal into the second total signal to form a second regular tracking error signal; And forming a combined tracking error signal by adding the first and second regular tracking error signals. Directing the reflected light beam reflected from the information bearing surface of the optical disc toward the first point in the first direction through the lens; and the first point in the first direction at a position capable of receiving at least a portion of the light beam A first distance from the first distance, having a first photosensitive region and a second and third photosensitive region on both sides of the first photosensitive region, wherein the first photosensitive region is composed of first and second photosensitive subregions; Detecting each part of the light beam with a first photodetector, each photosensitive region and each subregion forming an output proportional to an amount of incident light; Comparing the outputs of the first and second photosensitive sub-regions to form a first comparison tracking signal, and adding the outputs of the first and second photosensitive sub-regions and the second and third photosensitive sub-regions to add a first sum. Forming a signal; And dividing the first comparison tracking signal into the first sum signal to form a first normal tracking error signal, wherein the optical beam is reflected from the information bearing surface of the optical disc. 17. The method of claim 16, further comprising: converting a portion of the reflected light beam to a second point in a second direction by a prism positioned between the lens and the first point; And a fifth and a sixth photosensitive region in both the fourth photosensitive region and the fourth photosensitive region in a central portion, the fourth photosensitive region being spaced apart from the second point by the first distance in a second direction. A third and fourth photosensitive subregions, each photosensitive region and the photosensitive subregion detecting a portion of the converted light beam with a second photodetector for forming an output proportional to the amount of incident light; Comparing the outputs of the third and fourth photosensitive sub-regions to form a second comparison tracking signal, and adding the outputs of the third and fourth photosensitive sub-regions and the fifth and sixth photosensitive sub-regions to add a second sum. Forming a signal; And dividing the second comparison tracking signal into the second sum signal to form a second regular tracking error signal, and adding the first and second positive tracking error signals to form a combined tracking error signal. Error detection method. A lens for directing the reflected light beam reflected from the information bearing surface of the optical disc to the first point in the first direction; At a position capable of receiving at least a portion of the reflected light beam, the first distance from the first point in the first direction, divided into three parallel regions including one central portion and two outer portions on both sides of the central portion; The center portion is further divided into first and second photosensitive tracking regions, and the outer portion is composed of first and second photosensitive focus regions, and each photosensitive region is proportional to the amount of light incident on the photosensitive region. A first photodetector configured to form an output, and a prism positioned between the lens and the first point to convert a portion of the reflected light beam to a second point; One center of the second point facing the prism, separated from the second point by the first distance, divided into three parallel regions including one outer center and two outer sides on both sides of the central center, Is divided into third and fourth photosensitive tracking regions, and the outer portion is composed of third and fourth photosensitive focusing regions, each photosensitive region forming a second output which is proportional to the amount of light incident on the photosensitive region. Photodetectors; And a circuit connected to said first photodetector, said comparator for comparing a output of said first and second photosensitive tracking regions to form a first comparison tracking signal; An adder which adds outputs of the first and second photosensitive tracking regions and the first and second photosensitive focus regions to form a first sum signal; A dividing device which divides the first comparison tracking signal into the first sum signal to form a first normal tracking error signal; A comparison device comparing the outputs of the third and fourth photosensitive tracking regions to form a second comparison tracking signal; And an adder configured to add outputs of the third and fourth photosensitive tracking regions and the third and fourth photosensitive focus regions to form a second sum signal: dividing the second comparison tracking signal into the second sum signal A dividing apparatus for forming a regular tracking error signal; An adder which adds the first and second regular tracking error signals to form a combined tracking error signal, and an adder which adds outputs of the first and second photosensitive focus areas to form a first add focus signal; An adder for adding a first output of said first and second photosensitive tracking regions to form a first addition tracking signal; A comparison device for forming a first comparison focus signal by comparing the first addition focus signal with the first addition tracking signal, and dividing the first comparison focus signal by the first sum signal to form a first normal focus error signal A divider; An adder configured to add outputs of the third and fourth photosensitive focus regions to form a second added focus signal; An adder configured to add outputs of the third and fourth photosensitive tracking regions to form a second addition tracking signal; A comparison device for forming a second comparison focus signal by comparing the second addition focus signal with the second addition tracking signal; A dividing apparatus dividing the second comparison focus signal into the second total signal to form a second normal focus error signal; And the circuit comprising an adder which adds the first and second normal focus error signals to form a combined focus error signal, wherein the optical beam is reflected from the information bearing surface of the optical disc. ※ Note: The disclosure is based on the initial application.