US5297129A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Waveform shaping method and apparatus for optical recording
Assignee: Optical Disc Corp
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Filing: 1992-12-24
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Granted: 1994-03-22
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Expires: 2012-12-24
Abstract
Abstract Method and apparatus for improving the characteristics of the surface effects recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects or indicia in the moving recording medium when the writing beam is above threshold and incapable of forming surface effects in the moving recording medium when the writing beam is below threshold. The method includes receiving a substantially rectangular waveform having leading and trailing edges, provided as a modulator drive signal to modulate the writing beam to a peak power above threshold and to a minimum power level below thresholds, respectively, and producing a shaped modulator drive signal by increasing the peak power of the writing beam responsive to the occurrence of the leading edges, by decreasing the time the shaped modulator drive signal is above threshold in order to maintain a prescribed duty cycle in the track of surface effects in the moving recording medium, and by producing symmetrical leading and trailing edges of the surface effects.
Inventors
- 👤 Richard L. Wilkinson
- 👤 Stephen P. Brown
- 👤 Shigang Li
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:32
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/128; G11B7/004; G11B7/0045
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
235 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above the threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below the threshold, said waveform shaping circuit comprising: delay means for receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam, and for delaying said leading edges while passing said trailing edges undelayed; and waveform shaping means coupled to said delay means for producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 2
Dependent Claim
235 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above the threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below the threshold, said waveform shaping circuit comprising: delay means for receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam, and for delaying said leading edges while passing said trailing edges undelayed; and waveform shaping means coupled to said delay means for producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 3
Dependent Claim
21 words
The waveform shaping circuit as claimed in claim 1, wherein said trailing edges of said shaped modulator drive signal are linear.
Claim 4
Dependent Claim
26 words
The waveform shaping circuit as claimed in claim 1, wherein said waveform shaping means comprises means for varying the amplitude of said shaped modulator drive signal.
Claim 5
Dependent Claim
28 words
The waveform shaping circuit as claimed in claim 1, wherein said waveform shaping means comprises means for varying the average D.C. level of said shaped modulator drive signal.
Claim 6
Dependent Claim
31 words
The waveform shaping circuit as claimed in claim 1, wherein said waveform shaping means comprises means for varying the slope of the ramped trailing edges of said shaped modulator drive signal.
Claim 7
Dependent Claim
33 words
The waveform shaping circuit as claimed in claim 5, wherein said means for varying the slope of the ramped trailing edges of said shaped modulator drive signal comprises an adjustable constant current source.
Claim 8
Dependent Claim
56 words
The waveform shaping circuit as claimed in claim 1, wherein said delay means includes means for adjusting the delay of said leading edges by about 11/2T, where T is a fixed period of time defined in the rules for the EFM code standard in the recording and reproduction of information discs commonly known as compact discs.
Claim 9
Dependent Claim
98 words
The waveform shaping circuit as claimed in claim 1, wherein: said surface effects are pits in a recording surface of said moving recording medium; and the delay of said delay means and the amplitude and shape of said shaped modulator drive signal produced by said waveform shaping means are selected so as to form pits in said moving recording medium, which in relation to the lands between such pits along a track of alternate pits and lands, have a prescribed duty cycle with said lands when said rectangular waveform received by said delay means is a square wave.
Claim 10
Dependent Claim
79 words
The waveform shaping circuit as claimed in claim 1, wherein, under the influence of said shaped modulator drive signal, the writing beam forms said surface effects in the form of pits in said moving recording medium, said pits having leading edges formed by the steep leading edges of said shaped modulator drive signal, and having trailing edges formed by the ramped trailing edges of said shaped modulator drive signal, to thereby form pits with symmetrical leading and trailing edges.
Claim 11
Dependent Claim
69 words
The waveform shaping circuit as claimed in claim 9, wherein said waveform shaping means comprises means for adjusting the amplitude, average D.C. level and trailing edge slope of said shaped modulator drive signal to thereby produce pits in said moving recording medium which are shaped and which have a prescribed duty cycle with lands between pits when said rectangular waveform received by said delay means is a square wave.
Claim 12
Dependent Claim
210 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming surface discontinuities in the moving recording medium when the writing beam is above the threshold and incapable of forming surface discontinuities in the moving recording medium when the writing beam is below the threshold, said waveform shaping circuit comprising: waveform processing means for receiving a substantially rectangular waveform, having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam, and for producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 13
Dependent Claim
210 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming surface discontinuities in the moving recording medium when the writing beam is above the threshold and incapable of forming surface discontinuities in the moving recording medium when the writing beam is below the threshold, said waveform shaping circuit comprising: waveform processing means for receiving a substantially rectangular waveform, having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam, and for producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 14
Dependent Claim
21 words
The waveform shaping circuit as claimed in claim 11, wherein said trailing edges of said shaped modulator drive signal are linear.
Claim 15
Dependent Claim
26 words
The waveform shaping circuit as claimed in claim 11, wherein said waveform processing means comprises means for varying the amplitude of said shaped modulator drive signal.
Claim 16
Dependent Claim
28 words
The waveform shaping circuit as claimed in claim 11, wherein said waveform processing means comprises means for varying the average D.C. level of said shaped modulator drive signal.
Claim 17
Dependent Claim
31 words
The waveform shaping circuit as claimed in claim 11, wherein said waveform processing means comprises means for varying the slope of the ramped trailing edges of said shaped modulator drive signal.
Claim 18
Dependent Claim
33 words
The waveform shaping circuit as claimed in claim 15, wherein said means for varying the slope of the ramped trailing edges of said shaped modulator drive signal comprises an adjustable constant current source.
Claim 19
Dependent Claim
101 words
The waveform shaping circuit as claimed in claim 11, further comprising: delay means coupled to said waveform processing means for receiving said substantially rectangular waveform having said leading and trailing edges, provided as said modulator drive signal to modulate the writing beam, and for delaying said leading edges while passing said trailing edges undelayed; and wherein said delay means includes means for adjusting the delay of said leading edges by about 11/2T, where T is a fixed period of time defined in the rules for the EFM code standard in the recording and reproduction information discs commonly known as compact discs.
Claim 20
Dependent Claim
106 words
The waveform shaping circuit as claimed in claim 11, further comprising delay means coupled to said waveform processing means for delaying said leading edges while passing said trailing edges undelayed; and wherein the delay of said delay means and the amplitude and shape of said shaped modulator drive signal produced by said waveform processing means are selected so as to form pits in said moving recording medium, which in relation to the lands between such pits along a track of alternate pits and lands, have a prescribed duty cycle with said lands when said rectangular waveform received by said waveform processing means is a square wave.
Claim 21
Dependent Claim
72 words
The waveform shaping circuit as claimed in claim 11, wherein, under the influence of said shaped modulator drive signal, the writing beam forms pits in said moving recording medium, said pits having leading edges formed by the steep leading edges of said shaped modulator drive signal, and having trailing edges formed by the ramped trailing edges of said shaped modulator drive signal, to thereby form pits with symmetrical leading and trailing edges.
Claim 22
Dependent Claim
70 words
The Waveform shaping circuit as claimed in claim 19, wherein said waveform processing means comprises means for adjusting the amplitude, average D.C. level, and trailing edge slope of said shaped modulator drive signal to thereby produce pits in said moving recording medium which are shaped and which have a prescribed duty cycle with lands between pits when said rectangular waveform received by said waveform processing means is a square wave.
Claim 23
Dependent Claim
224 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below threshold, said waveform shaping circuit comprising: means for receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam to a peak power above threshold and to a minimum power level below threshold, respectively; and waveform shaping means coupled to said receiving means for producing a shaped modulator drive signal which increases the peak power of the writing beam responsive to the occurrence of said leading edges, decreases the time said shaped modulator drive signal is above the threshold to maintain a prescribed duty cycle in the track of surface effects in the moving recording medium, and produces a symmetrical geometry at the leading and trailing edges of said track of said surface effects.
Claim 24
Dependent Claim
224 words
A waveform shaping circuit for use in an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below threshold, said waveform shaping circuit comprising: means for receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam to a peak power above threshold and to a minimum power level below threshold, respectively; and waveform shaping means coupled to said receiving means for producing a shaped modulator drive signal which increases the peak power of the writing beam responsive to the occurrence of said leading edges, decreases the time said shaped modulator drive signal is above the threshold to maintain a prescribed duty cycle in the track of surface effects in the moving recording medium, and produces a symmetrical geometry at the leading and trailing edges of said track of said surface effects.
Claim 25
Independent Claim
222 words
A method for improving the characteristics in the indicia recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above the threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below the threshold, said method comprising the steps of: receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam; and producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 26
Independent Claim
222 words
A method for improving the characteristics in the indicia recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above the threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below the threshold, said method comprising the steps of: receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam; and producing a shaped modulator drive signal having steep leading edges reaching a first level sufficient to cause said writing beam to have an intensity above the threshold of the moving medium, and having ramped trailing edges changing amplitude at a prescribed rate to reach a second level sufficient to cause said writing beam to have an intensity below the threshold of the moving medium prior in time to the occurrence of the respective next leading edges of the received rectangular waveform.
Claim 27
Dependent Claim
86 words
The method as claimed in claim 22, including adjusting the width of the portion of said shaped modulator drive signal which, is above threshold, adjusting the slope of said ramped trailing edges, and adjusting the amplitude and D.C. offset of said shaped modulator drive signal to produce surface effects in said recording medium which have a prescribed duty cycle with areas between said surface effects along said track and which have geometric symmetry in the leading and trailing edges of said track of said surface effects.
Claim 28
Independent Claim
223 words
A method for improving the characteristics in the indicia recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below threshold, said method comprising the steps of: receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam to a peak power above threshold and to a minimum power level below threshold, respectively; and producing a shaped modulator drive signal by increasing the peak power of the writing beam responsive to the occurrence of said leading edges, decreasing the time said shaped modulator drive signal is above threshold to maintain a prescribed duty cycle in the track of surface effects in the moving recording medium, and producing a symmetrical geometry at the leading and trailing edges of said track of said surface effects.
Claim 29
Independent Claim
223 words
A method for improving the characteristics in the indicia recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects in the moving recording medium when the writing beam is above threshold and incapable of forming said track of surface effects in the moving recording medium when the writing beam is below threshold, said method comprising the steps of: receiving a substantially rectangular waveform having leading and trailing edges, provided as said modulator drive signal to modulate the writing beam to a peak power above threshold and to a minimum power level below threshold, respectively; and producing a shaped modulator drive signal by increasing the peak power of the writing beam responsive to the occurrence of said leading edges, decreasing the time said shaped modulator drive signal is above threshold to maintain a prescribed duty cycle in the track of surface effects in the moving recording medium, and producing a symmetrical geometry at the leading and trailing edges of said track of said surface effects.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-03-21 | 1997-09-20 | 1998-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-21 | 2001-09-20 | 2002-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-21 | 2005-09-20 | 2006-03-22 | $7700.00 | Window Closed / Lapsed |