Apparatus for integrated backlight and dynamic gamma/VCOM control on silicon chips
View Patent ↗Integrated backlight unit (BLU) and liquid crystal systems and circuits in liquid crystal display (LCD) systems are described. An LCD system can include a BLU to emit light at different intensities, and a BLU controller coupled to the BLU and configured to control the intensities. An LCD unit can receive the emitted light, and emanate light at a selected luminosity. The LCD unit can include pixels corresponding to: a liquid crystalline medium to provide a transmittance of the light emitted or to transmit a color light; and transistors adapted to modulate reference voltages. An LCD unit controller can be coupled to the LCD unit and configured to control luminosity of the light emanated from the LCD unit. The BLU and the LCD unit, which can be integrated in a single integrated circuit, can be controlled during concurrent time periods for contrast enhancement of images displayed from the LCD unit.
1. A liquid crystal display (LCD) system, comprising:
a backlight unit disposed to emit light at a plurality of intensities, wherein the backlight unit includes a plurality of light emitting diodes, one or more of the plurality of light emitting diodes being operably coupled to the backlight unit controller to be controlled to emit light at one of the plurality of intensities;
a backlight unit controller operably coupled to the backlight unit and configured to control the plurality of intensities of the light emitted from the backlight unit;
an LCD unit located adjacent to the backlight unit for receiving the light emitted from the backlight unit, and configured to be controlled to emanate light at a selected luminosity, wherein the LCD unit comprises a plurality of pixels, one or more of the plurality of pixels corresponding to:
a portion of a liquid crystalline medium adapted to provide a transmittance of the light emitted from a corresponding light emitting diode of the backlight unit; and
a plurality of transistors adapted to control the LCD unit by modulating one or more reference voltages; and
an LCD unit controller operably coupled to the LCD unit and configured to control a luminosity of the emanated light,
wherein the backlight unit and the LCD unit are configured to be controlled concurrently, and wherein the luminosity of a given pixel is controlled by varying the intensity of a light emitting diode corresponding to the given pixel and by varying the transmittance of the liquid crystalline medium corresponding to the given pixel, and wherein the backlight unit controller and LCD unit controller are configured so that a plurality of most significant bits of image data provide coarse intensity variation of the given pixel using the light emitting diode corresponding to the given pixel and a plurality of least significant bits provide finer intensity variation of the given pixel using the liquid crystalline medium, and wherein the given pixel comprises a pixel circuit receiving a gamma voltage, the gamma voltage dictating a luminosity of light emitted from the given pixel and controlling alternating direction of current flow across the pixel circuit,
wherein the LCD unit controller and the backlight unit controller are fabricated on an integrated circuit, and
wherein the given pixel comprises a pixel circuit including at least three transistors adapted for controlling emission of respective color lights, wherein each of the transistors receives a respective gamma voltage from a digital-to-analog converter coupled to a gamma voltage generator, wherein each of the transistors is a thin film transistor (TFT) and TFT gamma voltage controlling electronics are configured to control a TFT gamma voltage for the TFT transistor, wherein the source of the TFT transistor is coupled to a common node, wherein a current flow across the TFT transistor is controlled based on a difference between a voltage corresponding to the TFT gamma voltage and a voltage at the common node, wherein the backlight unit controller and the TFT gamma voltage controlling electronics are fabricated on the integrated circuit.
2. The LCD system of claim 1 , wherein the backlight unit controller is configured to control a first light emitting diode to emit light at a first one of the plurality of intensities and to control a second light emitting diode to, at the same time, emit light at a second one of the plurality of intensities, and wherein the first one of the plurality of intensities is independent of the second one of the plurality of intensities.
3. The LCD system of claim 2 , further comprising a timing controller operably coupled to the backlight unit controller and the LCD unit controller for causing synchronized control of the backlight unit and the LCD unit by outputting one or more signals adapted to be received by the backlight unit controller and the LCD unit controller,
wherein the one or more signals are for causing the backlight unit controller to control one or more of the plurality of light emitting diodes to emit light at one of the plurality of intensities during a first time period, and
wherein the one or more signals are for causing the LCD unit controller to control the LCD unit to emanate light at the selected luminosity during a second time period, the first time period being concurrent with the second time period.
4. The LCD system of claim 1 , wherein the liquid crystalline medium is a twisted nematic liquid crystal medium adapted to bend into one of a plurality of twist angles to provide the transmittance of the light emitted from the backlight unit.
5. The LCD system of claim 1 , further comprising:
a plurality of gamma voltage generators; and
a plurality of gate data signal generators,
one or more of the plurality of transistors being a thin film transistor (TFT) that is a field effect transistor having:
a drain coupled to one of the plurality of gamma voltage generators;
a gate coupled to one of the plurality of gate data signal generators; and
a source coupled to a storage capacitor that is coupled to a common voltage,
one or more of the plurality of the gamma voltage generators being configured to output a gamma voltage signal for controlling a transmission of a color signal, and
one or more of the plurality of the gate data signal generators being configured to output a gate data signal for controlling a current flow from the drain to the source of the TFT.
6. The LCD system of claim 5 , further comprising:
a plurality of first digital-to-analog converters; and
a plurality of second digital-to-analog converters,
wherein the gate of the TFT is coupled to one of the plurality of gate data signal generators one of the plurality of first digital-to-analog converters, and
wherein the drain of the TFT is coupled to one of the plurality of gamma voltage generators via one of the plurality of second digital-to-analog converters.
7. The LCD system of claim 1 , wherein one or more of the plurality of transistors is a thin film transistor (TFT) having a drain, a source and a gate, the LCD system further comprising:
a backlight unit modulator; and
electronics for controlling a voltage at the drain, the source or the gate,
wherein the backlight unit modulator and the electronics for controlling are fabricated on the integrated circuit.
8. The LCD system of claim 1 , wherein the LCD unit controller is configured to control gamma voltage modulation applied to the source or to the drain of the TFT.