Patent EP0227445A2 successfully refreshed from Google Patents.
EP0227445A2
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EP
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Methods of and apparatus for focusing servo control
Assignee: Sony Corp
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Filing: 1986-12-18
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Granted: —
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Expires: 2006-12-18
Abstract
Abstract A photodetector generates a focusing error signal (FE), a tracking error signal (TE) and an RF signal (RF), and a closed loop focusing servo circuit (10) is responsive to the focusing error signal applied thereto for focusing a light spot in position on an optical disc. The focusing error signal (FE) is detected synchronously with the tracking error signal (TE) in circuit blocks (22a,26a,26b) to produce a first periodic function signal. The focusing error signal (FE) is also detected synchronously with the RF signal (RF) in circuit blocks (22b.26c,26d) to produce a second periodic function signal. The tracking error signal (TE) is converted into a sine-wave signal having a predetermined amplitude in an AGC circuit 129a). The RF signal (RF) is converted into a cosine-wave signal having a predetermined amplitude in an AGC circuit (29b). The first periodic function signal is multiplied by the cosine-wave signal in a multiplier (28a) to produce a first component signal. The second periodic function signal is multiplied by the sine-wave signal in a multiplier (28b) to produce a second component signal. The first and second component signals are added in an adder (30) to produce a composed disturbance (W'(S)). The composed disturbance signal (W'(S)) is subtracted from the focusing error signal (FE) applied to the focusing servo circuit (10), thereby cancelling a disturbance (W(S)) superimposed on the focusing error signal (FE) applied to the focusing servo circuit (10).
Inventors
- 👤 Naoya C/O Patents Division Sony Corp. Eguchi
- 👤 Mikio C/O Patents Division Sony Corp. Sugiki
- 👤 Hitoshi C/O Patents Division Sony Corp. Okada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:30
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0941; G11B7/0908; G11B7/0909
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
210 words
A focusing control method utilising a photodetector (P) for generating a focusing error signal (FE), a tracking error signal (TE) and an RF signal (RF), and a closed loop focusing servo circuit (10) responsive to the focusing error signal (FE) applied thereto for focusing a light spot in position on an optical disc, the method comprising the steps of: detecting the focusing error signal (FE) synchronously with the tracking error signal (TE) to produce a first periodic function signal; detecting the focusing error signal (FE) synchronously with the RF signal (RF) to produce a second periodic function signal; converting the tracking error signal (TE) into a sine-wave signal having a predetermined amplitude; converting the RF signal (RF) into a cosine-wave signal having a predetermined amplitude; multiplying the first periodic function signal by the cosine-wave signal to produce a first component signal; multiplying the second periodic function signal by the sine-wave signal to produce a second component signal; adding the first and second component signals to produce a composed disturbance signal (W'(S)); and subtracting the composed disturbance signal (W'(S)) from the focusing error signal (FE) applied to said focusing servo circuit (10), thereby cancelling a disturbance (W(S)) superimposed on the focusing error signal (FE) applied to the focusing servo circuit (10).
Claim 2
Dependent Claim
210 words
A focusing control method utilising a photodetector (P) for generating a focusing error signal (FE), a tracking error signal (TE) and an RF signal (RF), and a closed loop focusing servo circuit (10) responsive to the focusing error signal (FE) applied thereto for focusing a light spot in position on an optical disc, the method comprising the steps of: detecting the focusing error signal (FE) synchronously with the tracking error signal (TE) to produce a first periodic function signal; detecting the focusing error signal (FE) synchronously with the RF signal (RF) to produce a second periodic function signal; converting the tracking error signal (TE) into a sine-wave signal having a predetermined amplitude; converting the RF signal (RF) into a cosine-wave signal having a predetermined amplitude; multiplying the first periodic function signal by the cosine-wave signal to produce a first component signal; multiplying the second periodic function signal by the sine-wave signal to produce a second component signal; adding the first and second component signals to produce a composed disturbance signal (W'(S)); and subtracting the composed disturbance signal (W'(S)) from the focusing error signal (FE) applied to said focusing servo circuit (10), thereby cancelling a disturbance (W(S)) superimposed on the focusing error signal (FE) applied to the focusing servo circuit (10).
Claim 3
Dependent Claim
95 words
A method according to claim 1, wherein the step of producing the first periodic function signal includes sampling the focusing error signal (FE) each time the tracking error signal (TE) crosses zero, the focusing error signal (FE) being inverted before it is sampled when the RF signal (RF) is negative, and wherein the step of producing the second periodic function signal includes sampling the focusing error signal (FE) each time the RF signal (RF) crosses zero, the focusing error signal (FE) being inverted before it is sampled when the tracking error signal (TE) is negative.
Claim 4
Dependent Claim
260 words
Focusing control apparatus comprising: a photodetector (P) for generating a focusing error signal (FE), a tracking error signal (TE) and an RF signal (RF); a closed loop focusing servo circuit (10) responsive to the focusing error signal (FE) applied thereto for focusing a light spot in position on an optical disc; a cancelling signal generator (20) connected to said photodetector (P) for producing a cancelling signal (W'(S)), said cancelling signal generator (20) including means (22a,26a,26b) for detecting the focusing error signal (FE) synchronously with the tracking error signal (TE) to produce a first periodic function signal, means (22b,26c,26d) for detecting the focusing error signal (FE) synchronously with the RF signal (RF) to produce a second periodic function signal, means (29a) for converting the tracking error signal (TE) into a sine-wave signal having a predetermined amplitude, means (29b) for converting the RF signal (RF) into a cosine-wave signal having a predetermined amplitude, means (28a) for multiplying the first periodic function signal by the cosine-wave signal to produce a first component signal, means (28b) for multiplying the second periodic function signal by the sine-wave signal to produce a second component signal, and means (30) for adding the first and second component signals to produce the cancelling signal (W'(S)); and said focusing servo circuit (10) including means (18) connected to said cancelling signal generator (20) for subtracting the cancelling signal (W'(S)) from the focusing error signal (FE) applied to said focusing servo circuit (10), thereby cancelling a disturbance (W(S)) superimposed on the focusing error signal (FE) applied to the focusing servo circuit (10).
Claim 5
Dependent Claim
260 words
Focusing control apparatus comprising: a photodetector (P) for generating a focusing error signal (FE), a tracking error signal (TE) and an RF signal (RF); a closed loop focusing servo circuit (10) responsive to the focusing error signal (FE) applied thereto for focusing a light spot in position on an optical disc; a cancelling signal generator (20) connected to said photodetector (P) for producing a cancelling signal (W'(S)), said cancelling signal generator (20) including means (22a,26a,26b) for detecting the focusing error signal (FE) synchronously with the tracking error signal (TE) to produce a first periodic function signal, means (22b,26c,26d) for detecting the focusing error signal (FE) synchronously with the RF signal (RF) to produce a second periodic function signal, means (29a) for converting the tracking error signal (TE) into a sine-wave signal having a predetermined amplitude, means (29b) for converting the RF signal (RF) into a cosine-wave signal having a predetermined amplitude, means (28a) for multiplying the first periodic function signal by the cosine-wave signal to produce a first component signal, means (28b) for multiplying the second periodic function signal by the sine-wave signal to produce a second component signal, and means (30) for adding the first and second component signals to produce the cancelling signal (W'(S)); and said focusing servo circuit (10) including means (18) connected to said cancelling signal generator (20) for subtracting the cancelling signal (W'(S)) from the focusing error signal (FE) applied to said focusing servo circuit (10), thereby cancelling a disturbance (W(S)) superimposed on the focusing error signal (FE) applied to the focusing servo circuit (10).
Claim 6
Dependent Claim
75 words
Apparatus according to claim 3, wherein said means for detecting the focusing error signal synchronously with the tracking error signal includes a first circuit (22a,26a,26b) for sampling the focusing error signal (FE) each time the tracking error signal (TE) crosses zero, and said means for detecting the focusing error signal synchronously with the RF signal includes a second circuit (22b,26c,26d) for sampling the focusing error signal (FE) each time the RF signal (RF) crosses zero.
Claim 7
Dependent Claim
229 words
Apparatus according to claim 4, wherein said first circuit includes means (22a) for producing a first drive pulse each time the tracking error signal (TE) crosses zero, a first sampling circuit (26a,27a) responsive to the first drive pulse for sampling the focusing error signal (FE), an inverter (23c) for inverting the focusing error signal (FE), a second sampling circuit (26b,27a) connected to said inverter (23c), said second sampling circuit (26b,27a) being responsive to the first drive pulse for sampling the inverted focusing error signal (FE), and means (23b,24a) for applying the first drive pulse to said first sampling circuit (26a,27a) when the RF signal (RF) is positive and to said second sampling circuit (26b,27a) when the RF signal (RF) is negative, and wherein said second circuit includes means (22b) for producing a second drive pulse each time the RF signal (RF) crosses zero, a third sampling circuit (26c,27b) responsive to the second drive pulse for sampling the focusing error signal (FE), a fourth sampling circuit (26d,27b) connected to said inverter (23c), said fourth sampling circuit (26d,27b) being responsive to the second drive pulse for sampling the inverted focusing error signal (FE), and means (23a,24b) for applying the second drive pulse to said third sampling circuit (26c,27b) when the tracking error signal (TE) is positive and to said fourth sampling circuit (26d,27b) when the tracking error signal (TE) is negative.
References Cited (Backward Citations)
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