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US 6,388,967 B2Granted
Liquid crystal driving signal generating apparatus and optical disk reproducing apparatus with liquid crystal driving signal generating apparatus
AssigneePioneer Corporation
InventorsJunichi Furukawa, Kiyoshi Tateishi, Noriaki Murao, Hiroaki Abe
Life of this patent
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Abstract
A liquid crystal driving signal generating apparatus comprises a PWM signal generator, a low pass filter for limiting a frequency band of a PWM signal outputted from the PWM signal generator, a liquid crystal panel connected to an output of the low pass filter, and a control means for controlling the PWM signal generator. The control means controls the PWM signal generator such that the PWM signal generator generates a PWM signal with a duty ratio corresponding to a refractive index to be set in the liquid crystal panel.
Claims51
A liquid crystal driving signal generating apparatus comprising:
- a PWM signal generator that generates a PWM signal;
- and
- a control circuit that controls said PWM signal generator to generate a PWM signal in which at least two types of duty ratios corresponding to a refractive index to be set in a liquid crystal are combined,
- wherein said refractive index corrects aberration caused by a tilt angle of a disk.
1 more element
An optical disk reproducing apparatus with a liquid crystal driving signal generating apparatus, comprising:
- a liquid crystal panel disposed between a light source and an objective lens;
- a PWM signal generator that generates a PWM signal;
- a detector that detects a tilt angle of a disk;
- and
- a controller that determines a refractive index to be set in said liquid crystal panel for correcting wave surface aberration caused by the tilt angle, and that controls said PWM signal generator such that said PWM signal generator generates a PWM signal in which at least two types of duty ratios corresponding to the refractive index are combined.
2 more elements
An apparatus, comprising:
- a pulse width modulation ( “PWM”) signal generator that generates a PWM signal;
- a liquid crystal that is driven by said PWM signal;
- a controller that receives information corresponding to a refractive index to be set in said liquid crystal and instructs said PWM signal generator to generate said PWM signal based on said information,
- wherein said PWM signal comprises a first signal portion having a first duty ratio and comprises a second signal portion having a second duty ratio,
- wherein said first duty ratio and said second duty ratio are different from each other, and
- wherein said refractive index corrects aberration caused by a tilt angle of a disk.
3 more elements
A liquid crystal driving signal generating apparatus comprising:
- a PWM signal generator that generates a PWM signal;
- and
- a control circuit that controls said PWM signal generator to generate a PWM signal in which at least two types of duty ratios corresponding to a refractive index to be set in a liquid crystal are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N (%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein N is greater than zero and less than 100.
2 more elements
An optical disk reproducing apparatus with a liquid crystal driving signal generating apparatus, comprising:
- a liquid crystal panel disposed between a light source and an objective lens;
- a PWM signal generator that generates a PWM signal;
- a detector that detects a tilt angle of a disk;
- and
- a controller that determines a refractive index to be set in said liquid crystal panel for correcting wave surface aberration caused by the tilt angle, and that controls said PWM signal generator such that said PWM signal generator generates a PWM signal in which at least two types of duty ratios corresponding to the refractive index are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N (%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein N is greater than zero and less than 100.
4 more elements
An apparatus, comprising:
- a pulse width modulation (“PWM”) signal generator that generates a PWM signal;
- a liquid crystal that is driven by said PWM signal;
- a controller that receives information corresponding to a refractive index to be set in said liquid crystal and instructs said PWM signal generator to generate said PWM signal based on said information,
- wherein said PWM signal comprises a first signal portion having a first duty ratio and comprises a second signal portion having a second duty ratio,
- wherein said first duty ratio equals N(%) and said second duty ratio equals 100-N(%),
- wherein said first duty ratio and said second duty ratio are different from each other, and
- wherein N is greater than zero and less than 100.
4 more elements
A liquid crystal driving signal generating apparatus comprising:
- a PWM signal generator that generates a PWM signal;
- and
- a control circuit that controls said PWM signal generator to generate a PWM signal in which at least two types of duty ratios corresponding to a refractive index to be set in a liquid crystal are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N(%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein said first PWM signal constitutes a first half of one cycle of said PWM signal and said second PWM signal constitutes a second half of said one cycle of said PWM signal.
2 more elements
An optical disk reproducing apparatus with a liquid crystal driving signal generating apparatus, comprising:
- a liquid crystal panel disposed between a light source and an objective lens;
- a PWM signal generator that generates a PWM signal;
- a detector that detects a tilt angle of a disk;
- and
- a controller that determines a refractive index to be set in said liquid crystal panel for correcting wave surface aberration caused by the tilt angle, and that controls said PWM signal generator such that said PWM signal generates a PWM signal in which at least two types of duty ratios corresponding to the refractive index are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N (%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein said first PWM signal constitutes a first half of one cycle of said PWM signal and said second PWM signal constitutes a second half of said one cycle of said PWM signal.
4 more elements
An apparatus, comprising:
- a pulse width modulation (“PWM”) signal generator that generates a PWM signal;
- a liquid crystal that is driven by said PWM signal;
- a controller that receives information corresponding to a refractive index to be set in said liquid crystal and instructs said PWM signal generator to generate said PWM signal based on said information,
- wherein said PWM signal comprises a first signal portion having a first duty ratio that equals N(%) and comprises a second signal portion having a second duty ratio that equals 100-N (%),
- wherein said first duty ratio and said second duty ratio are different from each other, and
- wherein said first signal portion constitutes a first half of one cycle of said PWM signal and said second signal portion constitutes a second half of said one cycle of said PWM signal.
3 more elements
A liquid crystal driving signal generating apparatus comprising:
- a PWM signal generator that generates a PWM signal;
- and
- a control circuit that controls said PWM signal generator to generate a PWM signal in which at least two types of duty ratios corresponding to a refractive index to be set in a liquid crystal are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N (%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein said duty ratio of said first PWM signal and said duty ratio of said second PWM signal have values that reduce a direct current component in said PWM signal to substantially zero.
2 more elements
An optical disk reproducing apparatus with a liquid crystal driving signal generating apparatus, comprising:
- a liquid crystal panel disposed between a light source and an objective lens;
- a PWM signal generator that generates a PWM signal;
- a detector that detects a tilt angle of a disk;
- and
- a controller that determines a refractive index to be set in said liquid crystal panel for correcting wave surface aberration caused by the tilt angle, and that controls said PWM signal generator such that said PWM signal generator generates a PWM signal in which at least two types of duty ratios corresponding to the refractive index are combined,
- wherein said PWM signal is formed by a first PWM signal with a duty ratio of N (%) and a second PWM signal with a duty ratio of 100-N (%), and
- wherein said duty ratio of said first PWM signal and said duty ratio of said second PWM signal have values that reduce a direct current component in said PWM signal to substantially zero.
4 more elements
An apparatus, comprising:
- a pulse width modulation (“PWM”) signal generator that generates a PWM signal;
- a liquid crystal that is driven by said PWM signal;
- a controller that receives information corresponding to a refractive index to be set in said liquid crystal and instructs said PWM signal generator to generate said PWM signal based on said information,
- wherein said PWM signal comprises a first signal portion having a first duty ratio that equals N(%) and comprises a second signal portion having a second duty ratio that equals 100-N (%),
- wherein said first duty ratio and said second duty ratio are different from each other, and
- wherein said first duty ratio and said second duty ratio have values that reduce a direct current component in said PWM signal to substantially zero.
3 more elements
Dependencies are inferred from the claim text.