Gray scale voltage generator, method of generating gray scale voltage and transmissive and reflective type liquid crystal display device using the same

A gray scale voltage generator for providing a gray scale voltage to a transmissive-and-reflective type liquid crystal display device, the gray scale voltage generator comprising:

• a first reflective mode gray scale data generating means receiving transmissive mode gray scale data, producing real reflective mode gray scale data corresponding to a first effective range of a reflective mode gray scale voltage using a relation between a second effective range of a transmissive mode gray scale voltage and the transmissive mode gray scale data, extracting an integer part from the real reflective mode gray scale data to produce first reflective mode gray scale data, and generating a control datum corresponding to a first figure below a decimal-point of each of the real reflective mode gray scale data;
• a frame counter receiving a frame synchronization signal indicating a beginning of each of the N frames and counting a number of the frame synchronization signal to produce a frame count value;
• a second reflective mode gray scale data generating means mixing the first reflective mode gray scale data and temporary reflective mode gray scale data in a predetermined ratio by N-frame period to produce second reflective mode gray scale data, the temporary reflective mode gray scale data being a sum of a first integer and the first reflective mode gray scale data;
• a third reflective mode gray scale data generating means inserting pseudo gray scale data into the second reflective mode gray scale data to produce a third reflective mode gray scale data, a first number of the pseudo gray scale data being a difference between a second number of a transmissive mode gray scale level and a third number of a reflective mode gray scale level;
• a mode judging means for determining one of a transmissive mode or a reflective mode to output a mode determining signal;
• and
• a selecting means providing the transmissive and reflective type liquid crystal display device with a transmissive mode gray scale data corresponding to the transmissive mode gray scale data when the mode determining signal represents the transmissive mode and providing the transmissive and reflective type liquid crystal display device with a reflective mode gray scale data corresponding to the third reflective mode gray scale data when the mode determining signal represents the reflective mode.

A gray scale voltage generator for providing a gray scale voltage to a transmissive and reflective type liquid crystal display device, the liquid crystal display device including a data driver for applying the gray scale voltage to pixels and a gate driver for controlling switching devices of the pixels and a light source, the gray scale voltage generator comprising:

• a controller for providing the liquid crystal display device with a transmissive mode gray scale data when the light source is turned on, and for providing the liquid crystal display device with a reflective mode gray scale data when the light source is turned off;
• a gamma reference voltage generator for generating a gamma reference voltage based on the transmissive mode gray scale data and the reflective mode gray scale data to output the gamma reference voltage to the data driver;
• and
• a common voltage generator for generating a common voltage to output the common voltage to a common line connected to the pixels.

A gray scale voltage generator for providing a gray scale voltage to a transmissive and reflective type liquid crystal display device, the liquid crystal display device including a data driver for applying the gray scale voltage to pixels and a gate driver for controlling switching devices of the pixels and a light source, the gray scale voltage generator comprising:

• a controller for providing the liquid crystal display device with a transmissive mode selecting signal when the light source is turned on, and for providing the liquid crystal display device with a reflective mode selecting signal when the light source is turned off;
• a gamma reference voltage generator for generating a transmissive mode gamma reference voltage and a reflective mode gamma reference voltage based on the transmissive mode selecting signal and the reflective mode selecting signal, respectively, to the data driver;
• and
• a common voltage generator for generating a common voltage to output the common voltage in response to the transmissive and reflective mode selecting signals to a common line connected to the pixels, the common voltage having a transmissive mode common voltage corresponding to a transmissive mode and a reflective mode common voltage corresponding to a reflective mode.

A liquid crystal display device comprising:

• a first insulation substrate;
• a first wiring formed on the first insulation substrate and extended in a first direction;
• a second wiring formed on the first insulation substrate and extended in a second direction to be insulated from the first wiring, the second direction being substantially perpendicular to the first direction;
• a transparent electrode formed in at least one pixel region, the pixel region defined by the first and second wiring;
• a reflective electrode disposed in the at least one pixel region and having a opening;
• a first thin film transistor substrate connected to the first wiring, the second wiring, the transparent electrode and the reflective electrode;
• a second insulation substrate facing the first insulation substrate;
• a common electrode formed on the second insulation substrate;
• and
• a liquid crystal layer interposed between the first and second insulation substrate, a major axis of each of liquid crystal molecules of the liquid crystal layer being twisted in a predetermined angle with respect to the first insulation substrate toward the second insulation substrate, the predetermined angle being in a range from about 0° to about 50°.

A liquid crystal display device comprising:

• a first insulation substrate;
• a first wiring formed on the first insulation substrate and extended in a first direction;
• a second wiring formed on the first insulation substrate and extended in a second direction to be insulated from the first wiring, the second direction being substantially perpendicular to the first direction;
• a transparent electrode formed in at least one pixel region, the pixel region defined by the first and second wiring;
• a reflective electrode disposed in the at least one pixel region and having a opening;
• a first thin film transistor substrate connected to the first wiring, the second wiring, the transparent electrode and the reflective electrode;
• a second insulation substrate facing the first insulation substrate;
• a common electrode formed on the second insulation substrate;
• and
• a liquid crystal layer interposed between the first and second insulation substrate, a major axis of each of liquid crystal molecules of the liquid crystal layer being twisted in a substantially perpendicular to the first and second insulation substrates, the liquid crystal layer being comprised of a chiral dopant so that the ratio of a cell gap to a pitch of the liquid crystal layer being in a range from about 0 to about 0.15.