REDUCING POWER CONSUMPTION IN A LIQUID CRYSTAL DISPLAY
First Claim
1. An apparatus, comprising:
- a bias voltage generator to generate a plurality of bias voltages; and
a drive buffer to drive a passive liquid crystal display (LCD) pixel or segment from at least one of the bias voltages, wherein the drive buffer actively drives the passive LCD segment or pixel in a first phase, and wherein the drive buffer ceases to drive the passive LCD segment or pixel in a second phase.
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Accused Products
Abstract
Embodiments of the invention relate to a method and apparatus to reduce power consumption in a passive matrix LCD driver circuit by using a plurality of drive buffers and active power management of sub-blocks in the passive matrix LCD drive circuit. Each drive buffer may operate in a first phase, which may include a high-drive mode to drive an LCD voltage to a threshold voltage level and a low-drive mode to modify the LCD voltage to approximate an input voltage of the drive buffer, and to maintain a constant LCD voltage level. The low-drive buffer consumes less current than the high-drive buffer, thus reducing power consumption. The drive buffer may also operate in a second phase, also a no-drive mode, in which the drive buffer and the bias voltage generator may be completely turned off, to further reduce power consumption. The drive buffer may be used to drive capacitive loads, as well as partially-resistive loads and inductive loads.
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Citations
20 Claims
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1. An apparatus, comprising:
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a bias voltage generator to generate a plurality of bias voltages; and a drive buffer to drive a passive liquid crystal display (LCD) pixel or segment from at least one of the bias voltages, wherein the drive buffer actively drives the passive LCD segment or pixel in a first phase, and wherein the drive buffer ceases to drive the passive LCD segment or pixel in a second phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method, comprising:
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generating an input voltage; actively driving a voltage associated with a passive liquid crystal display (LCD) segment or pixel to a threshold level in a first phase; modifying the voltage associated with the passive LCD segment or pixel to approximate the input voltage in the first phase; compensating a leakage associated with the passive LCD segment or pixel to maintain the voltage associated with the passive LCD segment or pixel at a substantially constant level in the first phase; and ceasing to drive the passive LCD segment or pixel associated with the passive LCD segment or pixel in a second phase. - View Dependent Claims (12, 13, 14, 15, 16)
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17. An apparatus, comprising:
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means for generating an input voltage; means for actively driving a voltage associated with a passive liquid crystal display (LCD) segment or pixel to a threshold level in a first phase; means for modifying the voltage associated with the passive LCD segment or pixel to approximate the input voltage in the first phase; means for compensating a leakage associated with the passive LCD segment or pixel to maintain the voltage associated with the passive LCD segment or pixel at a substantially constant level in the first phase; and means for ceasing to drive the passive LCD segment or pixel in a second phase. - View Dependent Claims (18, 19, 20)
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Specification