EP0277793A2
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EP
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Access control apparatus
Assignee: Sony Corp
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Filing: 1988-02-01
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Granted: —
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Expires: 2008-02-01
Abstract
Abstract An access control apparatus for use with a disc drive having a head (2) movable with respect to tracks (TR) on a disc (1) to produce a reproduced signal (RF) containing a data signal. The access control apparatus includes a drive device (4) for moving the head (2) in a direction (6) radially of the disc (1) to perform rapid access from one track to a desired track. A traverse detector (11) is provided for producing traverse detection pulses (SH) in response to the data signal. The traverse detector (11) includes a trigger signal generator (21) responsive to the data signal for producing trigger pulses (STH) for respective cycles of the data signal having a magnitude greater than a predetermined value, and a timer (22) responsive to each of the trigger pulses for changing to a first state. The timer returns to a second state a predetermined time after each trigger pulse occurs. A counter (6) counts the traverse detection pulses (SH) to accumulate a count corresponding to the number of tracks traversed by the head (2). The drive device (4) is controlled in accordance with the count in the counter (6). A second traverse detector (12) may also be provided for low speed traversing, an access speed detector (26) activating a switch (13) to select one of the traverse detectors (11, 12) depending upon the access speed of the head (2).
Inventors
- 👤 Shuichi C/O Patent Division Kimura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 02:05
CPC Classifications
G; G11; G11B; G11B21/00; G11B21/02; G11B21/08; G11B21/081; G11B21/083; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08541
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
199 words
Access control apparatus for a disc drive having a head (2) movable with respect to tracks (TR) on a disc (1) for reproducing a signal (RF) including a data signal (DATA), the apparatus comprising: means (4) responsive to a control signal for moving the head (2) in a direction radially of the disc (1) to perform access from one track to another track; traverse detector means (11) responsive to the data signal (DATA) included in the reproduced signal (RF) for producing traverse detection pulses (SH), the traverse detector means (11) including means (21) responsive to the data signal (DATA) for producing trigger pulses (K1) for respective cycles of the data signal having a magnitude greater than a predetermined value (VTH), and a timer (22) responsive to each of the trigger pulses (K1) for changing to a first state, the timer (22) returning to a second state a predetermined time (τ) after occurrence of each trigger pulse (K1); a counter (6) for counting the traverse detection pulses (SH) to accumulate a count corresponding to the number of tracks traversed by the head (2); and means (3) for producing the control signal in accordance with the count in the counter (6).
Claim 2
Dependent Claim
199 words
Access control apparatus for a disc drive having a head (2) movable with respect to tracks (TR) on a disc (1) for reproducing a signal (RF) including a data signal (DATA), the apparatus comprising: means (4) responsive to a control signal for moving the head (2) in a direction radially of the disc (1) to perform access from one track to another track; traverse detector means (11) responsive to the data signal (DATA) included in the reproduced signal (RF) for producing traverse detection pulses (SH), the traverse detector means (11) including means (21) responsive to the data signal (DATA) for producing trigger pulses (K1) for respective cycles of the data signal having a magnitude greater than a predetermined value (VTH), and a timer (22) responsive to each of the trigger pulses (K1) for changing to a first state, the timer (22) returning to a second state a predetermined time (τ) after occurrence of each trigger pulse (K1); a counter (6) for counting the traverse detection pulses (SH) to accumulate a count corresponding to the number of tracks traversed by the head (2); and means (3) for producing the control signal in accordance with the count in the counter (6).
Claim 3
Dependent Claim
28 words
Apparatus according to claim 1, wherein the predetermined time (τ) set in the timer (22) is slightly longer than the longest possible period of the data signal (DATA).
Claim 4
Dependent Claim
183 words
Apparatus according to claim 1 or claim 2, including: means (26) for detecting the speed of movement of the head (2); second traverse detector means (12) including a first low pass filter (LP1) having a first time constant, the first low pass filter (LP1) being arranged to receive the reproduced signal (RF) for producing a first filtered signal (S11), a second low pass filter (LP2) having a second time constant slower than the first time constant, the second low pass filter (LP2) being arranged to receive the reproduced signal (RF) for producing a second filtered signal (S12), and means (COM1) for producing second traverse detection pulses (SL) each produced when the first filtered signal (S11) is greater than the second filtered signal (S12); and a switching circuit (13) including means for supplying the first-mentioned traverse detection pulses (SH) to the counter (6) when the speed of movement of the head (2) exceeds a predetermined value and for supplying the second traverse detection pulses (SL) to the counter (6) when the speed of movement of the head (2) is less than the predetermined value.
Claim 5
Dependent Claim
127 words
Apparatus according to claim 1 or claim 2, including: means (26) for detecting the speed of movement of the head (2); second traverse detector means (12) including an integrating circuit (INT1) arranged to receive the reproduced signal (RF) for producing an integrated signal (S13), and means (COM2) for producing second traverse detection pulses (SL) each produced when the integrated signal (S13) is greater than a predetermined value; and a switching circuit (13) including means for supplying the first-mentioned traverse detection pulses (SH) to the counter (6) when the speed of movement of the head (2) exceeds a predetermined value and for supplying the second traverse detection pulses (SL) to the counter (6) when the speed of movement of the head (2) is less than the predetermined value.
Claim 6
Dependent Claim
185 words
Access control apparatus for a disc drive having a head (2) movable with respect to tracks (TR) on a disc (1) for reproducing a signal (RF) including a data signal (DATA), the apparatus comprising: means (4) responsive to a control signal for moving the head (2) in a direction radially of the disc (1) to perform access from one track to another track; first traverse detector means (11) for producing first traverse detection pulses (SH); second traverse detector means (12) for producing second traverse detection pulses (SL); means (26) for detecting the speed of movement of the head (2) to produce a signal (SSP) indicative of the detected head speed; switching circuit means (13) for selectively supplying the first or second traverse detection pulses (SH, SL) in accordance with the head speed detection signal (SSP); a counter (6) for counting the traverse detection pulses (STRV) fed thereto from the switching circuit means (13) to accumulate a count corresponding to the number of tracks traversed by the head (2); and means (3) for producing the control signal in accordance with the count of the counter (6).
Claim 7
Dependent Claim
185 words
Access control apparatus for a disc drive having a head (2) movable with respect to tracks (TR) on a disc (1) for reproducing a signal (RF) including a data signal (DATA), the apparatus comprising: means (4) responsive to a control signal for moving the head (2) in a direction radially of the disc (1) to perform access from one track to another track; first traverse detector means (11) for producing first traverse detection pulses (SH); second traverse detector means (12) for producing second traverse detection pulses (SL); means (26) for detecting the speed of movement of the head (2) to produce a signal (SSP) indicative of the detected head speed; switching circuit means (13) for selectively supplying the first or second traverse detection pulses (SH, SL) in accordance with the head speed detection signal (SSP); a counter (6) for counting the traverse detection pulses (STRV) fed thereto from the switching circuit means (13) to accumulate a count corresponding to the number of tracks traversed by the head (2); and means (3) for producing the control signal in accordance with the count of the counter (6).
References Cited (Backward Citations)
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