A method and apparatus for adapting and applying current boost levels to precharge current-driven elements in a matrix, and a method to make devices for this purpose. Elements are driven during successive scan cycles, each having a precharge period and an exposure period. One or more conduction voltages are sensed while an element conducts a selected exposure current, with early samples taken nearer the beginning of exposures and late samples taken nearer the end. Charge delivered during the precharge period is adjusted to reduce differences between early and late voltage samples.
RELATED APPLICATIONS
This application claims priority to, and hereby incorporates by reference, the following patent applications:
U.S. Provisional Patent Application No. 60/342,637, filed on Oct. 19, 2001, entitled PROPORTIONAL PLUS INTEGRAL LOOP COMPENSATION USING A HYBRID OF SWITCHED CAPACITOR AND LINEAR AMPLIFIERS;
U.S. Provisional Patent Application No. 60/343,856, filed on Oct. 19, 2001, entitled CHARGE PUMP ACTIVE GATE DRIVE;
U.S. Provisional Patent Application No. 60/343,638, filed on Oct. 19, 2001, entitled CLAMPING METHOD AND APPARATUS FOR SECURING A MINIMUM REFERENCE VOLTAGE IN A VIDEO DISPLAY BOOST REGULATOR;
U.S. Provisional Patent Application No. 60/342,582, filed on Oct. 19, 2001, entitled PRECHARGE VOLTAGE ADJUSTING METHOD AND APPARATUS;
U.S. Provisional Patent Application No. 60/346,102, filed on Oct. 19, 2001, entitled EXPOSURE TIMING COMPENSATION FOR ROW RESISTANCE;
U.S. Provisional Patent Application No. 60/353,753, filed on Oct. 19, 2001, entitled, METHOD AND SYSTEM FOR PRECHARGING OLED/PLED DISPLAYS WITH A PRECHARGE SWITCH LATENCY;
U.S. Provisional Patent Application No. 60/342,793, filed on Oct. 19, 2001, entitled ADAPTIVE CONTROL BOOST CURRENT METHOD AND APPARATUS, filed on Oct. 19, 2001;
U.S. Provisional Patent Application No. 60/342,791, filed on Oct. 19, 2001, entitled PREDICTIVE CONTROL BOOST CURRENT METHOD AND APPARATUS;
U.S. Provisional Patent Application No. 60/343,370, filed on Oct. 19, 2001, entitled RAMP CONTROL BOOST CURRENT METHOD AND APPARATUS;
U.S. Provisional Patent Application No. 60/342,783, filed on Oct. 19, 2001, entitled ADJUSTING PRECHARGE FOR CONSISTENT EXPOSURE VOLTAGE; and
U.S. Provisional Patent Application No. 60/342,794, filed on Oct. 19, 2001, entitled PRECHARGE VOLTAGE CONTROL VIA EXPOSURE VOLTAGE RAMP;
This application is related to, and hereby incorporates by reference, the following patent applications:
U.S. Provisional Application No. 60/290,100, filed May 9, 2001, entitled "METHOD AND SYSTEM FOR CURRENT BALANCING IN VISUAL DISPLAY DEVICES",
U.S. patent application Ser. No. 10/141,650 entitled "CURRENT BALANCING CIRCUIT", filed May 7, 2002;
U.S. patent application Ser. No. 10/141,325 entitled "CURRENT BALANCING CIRCUIT", filed May 7, 2002;
U.S. patent application Ser. No. 09/904,960, filed Jul. 13, 2001, entitled "BRIGHTNESS CONTROL OF DISPLAYS USING EXPONENTIAL CURRENT SOURCE";
U.S. patent application Ser. No. 10/141659, filed on May 7, 2002, entitled "MATCHING SCHEME FOR CURRENT CONTROL IN SEPARATE I.C.S.";
U.S. patent application Ser. No. 10/141326, filed May 7, 2002, entitled "MATCHING SCHEME FOR CURRENT CONTROL IN SEPARATE I.C.S.";
U.S. patent application Ser. No. 09/852,060, filed May 9, 2001, entitled "MATRIX ELEMENT VOLTAGE SENSING FOR PRECHARGE";
U.S. patent application Ser. No. 10/274,429 entitled "METHOD AND SYSTEM FOR PROPORTIONAL AND INTEGRAL LOOP COMPENSATION USING A HYBRID OF SWITCHED CAPACITOR AND LINEAR AMPLIFIERS", filed on even date herewith;
U.S. patent application Ser. No. 10/274,488 entitled "METHOD AND SYSTEM FOR CHARGE PUMP ACTIVE GATE DRIVE", filed on even date herewith;
U.S. patent application Ser. No. 10/274,428 entitled "METHOD AND CLAMPING APPARATUS FOR SECURING A MINIMUM REFERENCE VOLTAGE IN A VIDEO DISPLAY BOOST REGULATOR", filed on even date herewith;
U.S. patent application Ser. No. 10/141,648, filed May 7, 2002, entitled "APPARATUS FOR PERIODIC ELEMENT VOLTAGE SENSING TO CONTROL PRECHARGE";
U.S. patent application Ser. No. 10/141,318, filed May 7, 2002, entitled "METHOD FOR PERIODIC ELEMENT VOLTAGE SENSING TO CONTROL PRECHARGE,";
U.S. patent application Ser. No. 10/744,489 entitled "MATRIX ELEMENT PRECHARGE VOLTAGE ADJUSTING APPARATUS AND METHOD", filed on even date herewith;
U.S. patent application Ser. No. 10/274,491 entitled "SYSTEM AND METHOD FOR EXPOSURE TIMING COMPENSATION FOR ROW RESISTANCE", filed on even date herewith;
U.S. patent application Ser. No. 10/274,421 entitled "METHOD AND SYSTEM FOR PRECHARGING OLED/PLED DISPLAYS WITH A PRECHARGE LATENCY", filed on even date herewith;
U.S. Provisional Application No. 60/348,168 filed Oct. 19, 2001, entitled "PULSE AMPLITUDE MODULATION SCHEME FOR OLED DISPLAY DRIVER", filed on even date herewith;
U.S. patent application Ser. No. 10/029,563, filed Dec. 20, 2001, entitled "METHOD OF PROVIDING PULSE AMPLITUDE MODULATION FOR OLED DISPLAY DRIVERS";
U.S. patent application Ser. No. 10/029,605, filed Dec. 20, 2001, entitled "SYSTEM FOR PROVIDING PULSE AMPLITUDE MODULATION FOR OLED DISPLAY DRIVERS";
U.S. patent application Ser. No. 10/275,490 entitled "PREDICTIVE CONTROL BOOST CURRENT METHOD AND APPARATUS", filed on even date herewith;
U.S. patent application Ser. No. 10/274,500 entitled "RAMP CONTROL BOOST CURRENT METHOD", filed on even date herewith;
U.S. patent application Ser. No. 10/274,511 entitled "METHOD AND SYSTEM FOR ADJUSTING PRECHARGE FOR CONSISTENT EXPOSURE VOLTAGE", filed on even date herewith;
U.S. patent application Ser. No. 10/274,502 entitled "METHOD AND SYSTEM FOR RAMP CONTROL OF PRECHARGE VOLTAGE", filed on even date herewith;
In a selection period for applying a selection voltage to a scanning strip, a high impedance section for placing a data strip in a high impedance state is provided after a constant current section for supplying a constant current to a data strip from a constant current circuit. An organic electroluminescent element to be used has a small voltage-dependency in luminous efficiencies. When performing grayshade display by PWM, a data strip is supplied with an amount of electric charges from the constant current circuit in the constant current section, the amount of electric charges being calculated by adding an amount of residual electric charges in pixels to an amount of electric charges corresponding to luminance required for respective gray scale levels, the amount of residual electric charges being found based on an estimated potential at the data strip at end of the high impedance section.
The invention relates to a display device comprising a plurality of light emitting elements (1), wherein at least one of the elements has an associated capacitor (C1). The display device comprises pre-charging means (7;8) for generating a pre-charge signal for charging the associated capacitor (C1) at least partly. The pre-charging means (7;8) are adapted for generating a pre-charge signal comprising at least a first pre-charge signal in a first pre-charge stage and a second pre-charge signal in a second pre-charge stage. The pre-charge signal preferably comprises a current pre-charge signal followed by a voltage pre-charge signal. The combined pre-charge signal has the advantage of fast, but accurate pre-charging.
Disclosed herein is an internal voltage supply circuit for a semiconductor device. The internal voltage supply circuit includes a first voltage driver for supplying a first voltage in response to a first enable signal, a second voltage driver for supplying a second voltage in response to a second enable signal, and a first enable signal generator for generating the first enable signal having an enable period of a desired time according to a current drive capability of the semiconductor device. The enable period is set to be shorter than a predetermined reference period when the current drive capability of the semiconductor device is higher than a predetermined reference current drive capability, and the enable period is set to be longer than the reference period when the current drive capability of the semiconductor device is lower than the reference current drive capability.
When the ambient temperature of an organic electroluminescent display device is a low temperature, a capacitive charge driving method is performed to supply a constant current to a column electrode after performing capacitance charge and then apply a constant voltage to the column electrode to turn off a pixel; and when the ambient temperature is room temperature or a high temperature, an electric charge control driving method is performed to supply a constant current to the data electrode and then place the column electrode in a high impedance state. In the electric charge control driving method, a driving section is set in a selection period so as to be shorter than the selection period, and the amount of electric charges supplied to the pixel in the driving section is controlled depending on a required luminance.
Disclosed herein is an internal voltage supply circuit for a semiconductor device. The internal voltage supply circuit includes a first voltage driver for supplying a first voltage in response to a first enable signal, a second voltage driver for supplying a second voltage in response to a second enable signal, and a first enable signal generator for generating the first enable signal having an enable period of a desired time according to a current drive capability of the semiconductor device. The enable period is set to be shorter than a predetermined reference period when the current drive capability of the semiconductor device is higher than a predetermined reference current drive capability, and the enable period is set to be longer than the reference period when the current drive capability of the semiconductor device is lower than the reference current drive capability.
