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US 6,184,855 B2Granted
Liquid crystal display panel driving device
AssigneeInternational Business Machines Corporation
InventorsYoshinao Kobayashi, Akihiro Kuroda, Yoshitami Sakaguchi
Life of this patent
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Abstract
An analog driver for a liquid crystal display has sample hold circuits and buffer amplifiers divided into one group for positive inputs and the other groups for negative inputs which buffer amplifiers are selected in accordance with a first and second control signals thereby reducing the power consumption by the driver of buffer amplifiers. Furthermore, when none of the buffer amplifiers are selected, the data lines are held at common voltage to reduce the consumed power by the buffer amplifiers.
Claims16
An LCD panel driver, comprising:
- a first plurality of sample hold and buffer amplification units for positive inputs each including a sample hold circuit for sampling and holding an input video signal having a positive polarity in response to a first control signal and having a first buffer amplifier activated during said holding for charging a data line in an LCD panel;
- a second plurality of sample hold and buffer amplification units for negative input each including a sample hold circuit for sampling and holding an input video signal having a negative polarity in response to a second control signal and having a buffer amplifies activated during said holding for discharging a data line in the LCD panel;
- an output selector for selecting in response to a third control signal one or another of said buffer amplifies in a group including one of said first plurality of sample hold and buffer amplification units for positive input and one of said second plurality of sample hold and buffer amplification units for negative inputs, said outputs selector having means for making said data line a common voltage selected to reduce power consumption by the buffer amplifiers while neither buffer amplifier in the group is selected;
- a bidirectional shift register for generating sampling pulses;
- and
- a controller for generating said first and second control signals which control the timing of sampling and holding in said sample hold circuits and said third control signal from a mode specification signal specifying whether one-sided drive or two-sided drive, and HV inversion or H inversion are performed, a fourth control signal created in response to a Horizontal sync. signal and Vertical sync. signal to control the polarity of output voltage to said LCD panel and said sampling pulses.
3 more elements
An LCD panel driver, comprising:
- a first plurality of sample hold and buffer amplification units for positive inputs each including a sample hold circuit for sampling and holding an input video signal having a positive polarity in response to a first control signal and having a buffer amplifier activated during said holding for charging a data line in an LCD panel;
- a second plurality of sample hold and buffer amplification units for negative inputs each including a sample hold circuit for sampling and holding an input video signal having a negative polarity in response to a second control signal and having a buffer amplifier activated during said holding for discharging a data line in the LCD panel;
- an output selector for selecting in response to a third control signal one or another of said buffer amplifiers in a group including one of said first plurality of sample hold and buffer amplification units for positive input and one of said second plurality of sample hold and buffer amplification units for negative input, said output selector having means for making said data line a common voltage chosen to reduce power consumption by the buffer amplifiers while no buffer amplifier in the group is selected;
- a bidirectional shift register for generating sampling pulses;
- a controller for generating said third control signal and a fifth control signal for distributing said sampling pulses to said sample hold and buffer amplification units for positive input and said sample hold and buffer amplification units for negative input from a mode specification signal specifying whether one-sided drive or two-sided drive, and HV inversion or H inversion are to be performed and a fourth control signal created in response to a Horizontal sync. signal and Vertical sync. signal to control the polarity of output voltage to said LCD panel;
- and
- a plurality of pulse distributors for generating said first and second control signals which control the timing of sampling and holding in said sample hold circuits from said fifth control signal and said sampling pulses.
4 more elements
An LCD panel driver, comprising:
- a first plurality of sample hold and buffer amplification units for positive inputs each including a sample hold circuit for sampling and holding an input video signal having a positive polarity in response to a first control signal and having a buffer amplifier activated during said holding for charging a data line in an LCD panel;
- a second plurality of sample hold and buffer amplification units for negative inputs each including a sample hold circuit for sampling and holding an input video signal having a negative polarity in response to a second control signal and having a buffer amplifier activated during said holding for discharging a data line in the LCD panel;
- an output selector for select in response to a third control signal one or another of said buffer amplifiers in a group including one of said first plurality of sample hold and buffer amplification units for positive input and one of said second plurality of sample hold and buffer amplification units for negative input, said output selector having means for making said data line a common voltage chosen to reduce power consumption by the buffer amplifiers while no buffer amplifier in the group is selected;
- a bidirectional shift register for generating sampling pulses;
- and
- a controller for generating said third control signal and a fourth control signal which controls the polarity of the output to said LCD panel from a mode signal specifying whether one-sided drive or two-sided drive, and HV inversion or H inversion are to be performed and from a Horizontal sync. signal and Vertical sync. signal;
- and
- a plurality of pulse distributors for generating said first and second control signals which control the timing of sampling and holding in said sample hold circuits from said fourth control signal and said sampling pulses.
5 more elements
A liquid crystal display comprising:
- an LCD panel;
- and
- an LCD panel driver, wherein said LCD panel driver comprises:
- a first plurality of sample hold and buffer amplification units for positive inputs each including a sample hold circuit for sampling and holding an input video signal having a positive polarity in response to a first control signal and having a buffer amplifier activated during said holding for charging a data line in the LCD panel;
- a second plurality of sample hold and buffer amplification units for negative inputs each including a sample hold circuit for sampling and holding an input video signal having a negative polarity in response to a second control signal and having a buffer amplifier activated during said holding for discharging a data line in the LCD panel;
- an output selector for selecting in response to a third control signal one of said buffer amplifiers in a group including one of said plurality of sample hold and buffer amplification units for positive input and one of said plurality of sample hold and buffer amplification units for negative input, said output selector having means for making said data line a common voltage selected to reduce power consumption of the buffer amplifiers while no buffer amplifier is selected;
- a bidirectional shift register for generating sampling pulses;
- and
- a controller for generating, said first and second control signals which control the timing of sampling and holding in said sample and hold circuits and said third control signal from a mode specification signal specifying whether one-sided drive or two-sided drive, and HV inversion or H inversion are to be performed, a fourth control signal created in response to a Horizontal sync. signal and Vertical sync. signal to control the polarity of output voltage to said LCD panel and said sampling pulses.
6 more elements
Dependencies are inferred from the claim text.