Method and apparatus for dynamically and adjustably generating active matrix liquid crystal display gray level voltages

An apparatus to generate an adjustable voltage waveform of a constant, repeating period from which actual gravy scale levels for LCD pixels, which can differ from original gray scale instructions for the LCD pixels, are selected by an active matrix LCD, the apparatus allowing LCD special effects and compensation for LCD viewing and performance problems comprising:

• an active matrix LCD including a plurality of pixels each having an adjustable transmissivity proportional to a voltage potential applied across the pixel, the transmissivity varying from T-max to T-min which correlates with voltage potentials V-max to V-min, the transmissivity range being called actual gray scale, the transmissivity of an individual pixel being called actual gray scale level for the pixel, at least one LCD driver including an electrical device to set a voltage potential from one of the adjustable voltage waveforms across each pixel, and a driver device for presenting original gray scale instructions for each pixel for a given time to the LCD display;
• a display controller of the type including a data device to present data to the driver device of the LCD, the data representing the original gray scale instructions as to gray scale for individual pixels, a voltage generating means for generating the adjustable voltage waveforms-separate from the data, each having a repeating constant period, and each containing a plurality of voltage potentials between V-max and V-min from which the voltage potential across each pixel can be selected, and a timing control including a timing device to correlate presentation of the data and the repeating, constant periods of the voltage waveforms to each driver of the LCD;
• and
• adjustment circuitry added to the display controller, including a modification device to operate upon the adjustable voltage waveforms and alter at least portions of some of the adjustable voltage waveforms without altering the original gray scale instructions in the corresponding data, to alter voltage potential across selected pixels of the LCD from that instructed by the original gray scale instructions;
• wherein the adjustment circuitry includes a digital to analog converter, and a digital means carrying instructions to alter the repeating voltage waveform;
• wherein the digital means includes an information storage means for storing predetermined values for altering the repeating voltage waveform;
• wherein the adjustment circuitry includes temperature sensors and the information storage means includes predetermined values based on temperature information.

A means for compensating and controlling relative brightness of selected pixels of an active matrix LCD to solve off-axis viewing angle and temperature-caused brightness variations, the LCD including a plurality of pixels arranged in an array of columns and rows, an electrical device associated with each pixels to set a voltage potential across the pixel where the set voltage potential determines the transmissivity through an intended brightness of the pixel, digital data devices to receive digital gray scale instructions for each row of pixels, and conversion-devices to time and convert the digital gray scale instructions into corresponding voltage potentials across rows of pixels, a display controller including a data transfer device to send said digital gray scale instructions to the digital data devices of the LCD, a timing device to control timing for the display controller and the LCD, and a voltage waveform generator including a device to produce a repeating voltage waveform of constant period and shape used to produce the voltage potentials at the pixels, the improvement comprising:

• means connected to the display controller for selectivity altering at least portions of selected repeating voltage waveforms to a shape different from the repeating voltage waveforms according to predetermined compensation and control characteristics so that voltage potentials and actual transmissivity for selected pixels are altered from voltage potentials and transmissivity that would occur if the digital gray scale instructions solely controlled voltage potentials for the selected pixels without altering the digital gray scale instructions, to achieve desired brightness compensation for at least a portion of the LCD.

A method for altering an actual gray scale level from an instructed gray scale value generated by a display control for an active matrix LCD without altering the instructed gray scale value where the display control separately issues an instructed gray scale value for a pixel and a repeating voltage waveform of constant period and shape, the instructed gray scale value being correlated to a proportional gray scale voltage contained in the repeating voltage waveform generated in the display control, the proportional gray scale voltage being used to set up a voltage potential at the pixel to produce a transmissivity level through the pixel correlated to said instructed gray scale value, comprising:

• determining the amount of adjustment desired between said instructed gray scale value and said actual gray scale value for the pixel, the step of determining the amount of adjustment including considering the instructed gray scale value and the transmissivity level desired through the pixel for the LCD;
• generating an adjusted voltage waveform different from a selected repeating voltage waveform based on the amount of adjustment desired by changing one or more portions of the repeating voltage waveform used for the pixel;
• and
• utilizing the instructed gray scale value to select a location and corresponding voltage potential on the adjusted voltage waveform to drive the pixel to an adjusted voltage potential different from said proportional gray scale voltage to achieve the actual gray scale value and desired transmissivity level at the pixel without altering the instructed gray scale value for the pixel.

An apparatus for color correction compensation for on and off-axis viewing of an area of an LCD comprising an array of pixels, the array consisting of sets of pixels having green, blue, and red filters for color reproduction purposes, the pixels being driven by a display controller of the type which includes a data device which sends to the LCD a first signal containing digital gray scale instructions for each row of pixels and a voltage generator which sends to the LCD a second signal containing a repeating voltage waveform of constant period and shape and separate from the digital gray scale instructions but correlated to a set of gray scale values and from which a correlated voltage potential for a given pixel can be selected, so that rows of pixels, each having an instructed gray scale value, are successively entered to produce a composite color graphic on the LCD comprising:

• a waveform adjustment component in the display controller to vary selected repeating voltage waveforms in a spatially modulated form to in turn vary actual voltage potential for individual pixels or sets of pixels from correlated voltage potential based on an instructed gray scale values, but without altering the digital gray scale instructions, so that a viewer will average the pixels to the desired color when viewing from both on-axis and off-axis directions, the waveform adjustment component including an information storage means containing data correlated to viewing angle for pixels or sets of pixels at a portion of the LCD, data correlated to effect of viewing angle on perceived brightness for pixels or sets of pixels of said portion of the LCD, and data correlated to spatial modulation values for closely spaced pixels or sets of pixels at said portion of the LCD, the spatial modulation values comprising complimentary voltage potentials which differ in magnitude from each other and from the correlated voltage potentials based on the digital gray scale instructions for selected pixels or sets of pixels;
• a presentation component to present the spatially modulated complimentary voltage potentials to alternating rows of pixels so that voltage potentials at closely spaced pixels or sets of pixels will alternate between the complimentary voltage potentials and an observer from on and off axis viewing positions will average the relative brightness of the pixels or sets of pixels in said portion of the LCD to a brightness and color approximately equivalent to that instructed by the digital gray scale instructions for said portion of the LCD.

A method of color correction for off-axis viewing of an LCD where color is created by providing appropriate gray scale values to each pixel in an array of closely spaced sets of blue, green, and red pixels in an area of the LCD, producing the gray scale values by issuing a first signal comprising row-by-row digital gray scale instructions from a display controller and by issuing from a voltage waveform generator a second signal comprising a repeating voltage waveform of constant period and shape having normal gray scale voltages correlated to gray scale and from which is selected actual driving voltage for each pixel based on information in the first signal, and timing presentation to the pixels of the repeating voltage waveform with each row of digital gray scale instructions, comprising:

• determining the effect of off-axis viewing angle on color perceived by a viewer for the area of the LCD;
• varying the actual driving voltage of selected pixels in a spatially modulated manner to cause a viewer to perceive a correct color which would be perceived as other than the correct color because of the off-axis viewing angle, by altering the shape of selected repeating voltage waveforms to cause selected rows of pixels to be provided, in said second signal a first adjusted voltage waveform having gray scale voltage magnitudes of first amounts compared to normal gray scale voltages, and to cause selected rows of pixels to be provided a second adjusted voltage waveform having gray scale voltage magnitudes of second amounts compared to normal gray scale voltages and differing from said first amounts, so that closely spaced pixels will be driven to voltage potentials which vary from one another and a viewer of said area of the LCD would average closely spaced pixels for said off-axis viewing angle to perceive the correct color as intended by the digital gray scale instructions for said area but without altering the digital gray scale instructions in said first signal.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes a sensing device;
• wherein the sensing device is a temperature sensor.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods, timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes a sensing device:
• wherein the sensing device is a view angle sensor.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes a manipulatable control.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes an information device;
• wherein the information device is a component containing information relating to view angle.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes an information device;
• wherein the information device is a component containing information relating to background brightness.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes an information device;
• wherein the information device is a component containing information regarding transmissivity relative to temperature.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes an information device;
• wherein the information device is a component containing information relating to complimentary colors.

An LCD controller of the type where digital data containing instructed gray scale for rows of pixels is passed in a first signal to a driver of pixels of an active matrix LCD, a voltage ramp of constant period and repeating, non-varying shape is generated and passed in a second signal to the driver of the LCD, and a timed switching component converts the digital data into analog voltages correlated to the instructed gray scale at the pixels, the improvement comprising:

• a circuit added to the display, controller including a component to alter selected voltage ramps in the second signal into adjusted waveforms that are altered to effect the transmittance of selected pixels or sets of pixels without altering the digital data in the first signal so that actual analog voltages set up in selected pixels differ from analog voltages that would have been set up in those pixels if the unaltered selected voltage ramps had been used, thereby compensating or altering the transmittance and actual perceived gray scale without altering the instructed gray scale in the first signal;
• wherein the circuit comprises a voltage generating control producing voltage waveforms in successive equal periods timed to presentation of digital data to the LCD;
• an input component presenting information to the voltage generating control which at least in part determines the voltage waveform for each successive period;
• wherein the input component includes an information device;
• wherein the information device contains information relating to spatial averaging of pixel transmissivity.

A method for selectivity adjusting actual perceived gray scale for a set of pixels of an LCD in a LCD apparatus which includes a display controller which passes digital instructed gray scale values in a first signal to a driver for the LCD and generates a repeating, non-varying linear voltage ramp in a second signal that is made available to each of the pixels of the LCD, so that the instructed gray scale value for each refresh time for the LCD for each pixel is picked from a correlated position along the repeating non-varying voltage ramp to present a known correlated voltage based on the instructed gray scale value to each pixel, comprising:

• determining desired adjustment of actual perceived gray scale to the set of pixels;
• passing the digital data in the first signal of the display controller containing the instructed gray scale values to the LCD without modification;
• modifying at least one repeating non-varying voltage ramp in the second signal of the display controller into an adjusted voltage waveform of equal period to the voltage ramp, making the adjusted voltage waveform available to each of the pixels, and correlating its presentation to the set of pixels in a form and at a time needed to vary the voltage and the actual perceived gray scale at selected pixels of the set of pixels;
• wherein the voltage ramp is adjusted to alter presentation of the voltage to pixels at a selected portion of the LCD based on information related to viewing angle to the LCD.

A method for selectivity adjusting actual perceived gray scale for a set of pixels of an LCD in a LCD apparatus which includes a display controller which passes digital instructed gray scale values in a first signal to a driver for the LCD and generates a repeating, non-varying linear voltage ramp in a second signal that is made available to each of the pixels of the LCD, so that the instructed gray scale value for each refresh time for the LCD for each pixel is picked from a correlated position along the repeating non-varying voltage ramp to present a known correlated voltage based on the instructed gray scale value to each pixel, comprising:

• determining desired adjustment of actual perceived gray scale to the set of pixels;
• passing the digital data in the first signal of the display controller containing the instructed gray scale values to the LCD without modification;
• modifying at least one repeating non-varying voltage ramp in the second signal of the display controller into an adjusted voltage waveform of equal period to the voltage ramp, making the adjusted voltage waveform available to each of the pixels, and correlating its presentation, to the set of pixels in a form and at a time needed to vary the voltage and the actual perceived gray scale at selected pixels of the set of pixels;
• wherein the voltage ramp is adjusted based on information regarding temperature at or near the LCD.

A method for selectivity adjusting actual perceived gray scale for a set of pixels of an LCD in a LCD apparatus which includes a display controller which passes digital instructed gray scale values in a first signal to a driver for the LCD and generates a repeating, non-varying linear voltage ramp in a second signal that is made available to each of the pixels of the LCD, so that the instructed gray scale value for each refresh time for the LCD for each pixel is picked from a correlated position along the repeating non-varying voltage ramp to present a known correlated voltage based on the instructed gray scale value to each pixel, comprising:

• determining desired adjustment of actual perceived gray scale to the set of pixels;
• passing the digital data in the first signal of the display controller containing the instructed gray scale values to the LCD without modification;
• modifying at least one repeating non-varying voltage ramp in the second signal of the display controller into an adjusted voltage waveform of equal period to the voltage ramp, making the adjusted voltage waveform available to each of the pixels, and correlating its presentation to the set of pixels in a form and at a time needed to vary the voltage and the actual perceived gray scale at selected pixels of the set of pixels;
• wherein the voltage ramp is adjusted based on desired change in intensity of selected portions of the LCD.