Timing-Integrated ADC Circuit for Accurate AMOLED Current Sensing
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Solution Overview
Problem
Conventional analog-to-digital conversion methods in AMOLED display apparatuses lack accuracy, leading to non-uniform OLED light emission due to instability in thin-film transistor fabrication and aging, which affects external electrical compensation.
Innovation Solution
An analog-to-digital conversion (ADC) circuit incorporating an operational amplifier, integral capacitor, comparator, and timer, which converts an analog current signal to a digital signal by comparing output voltages and using timing operations to generate binary data, along with optional sub-circuits for reset, level conversion, and timing control to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analog-to-digital conversion methods are used, then the conversion process is simple, but the conversion accuracy is insufficient
Solution Approach 1:
The ADC circuit is divided into distinct functional modules: integral circuit (with operational amplifier and integral capacitor), comparator, timer, and reset sub-circuit. Each module performs a specific function in the conversion process, allowing for optimized design of each component while maintaining overall system accuracy.
Solution Approach 2:
The integral circuit performs preliminary integration of the analog current signal before comparison and timing operations. This preliminary action of integrating the signal over a fixed period prepares the signal for accurate digital representation by converting current to voltage and accumulating the signal energy.
2Stability of the object's composition
If external electrical compensation is performed, then OLED light emission uniformity can be improved, but the compensation accuracy is limited by conventional ADC conversion
Solution Approach 1:
The ADC circuit enables accurate feedback-based external electrical compensation by precisely converting the analog current signal from the signal-collection line to digital form. The timer measures the duration of the output signal, and this measurement is fed back to adjust the compensation current, creating a closed-loop system that improves light emission uniformity.
Solution Approach 2:
The patent replaces conventional low-accuracy ADC conversion methods with a timing-based measurement system. Instead of using complex high-resolution ADC hardware, the system substitutes a simpler timing mechanism that measures the duration of the comparator output signal, achieving high precision through time measurement rather than direct voltage comparison.
3Reliability
If a signal-collection line is used to collect analog current signal, then pixel current can be monitored, but parasitic parameters affect the signal accuracy
Solution Approach 1:
The operational amplifier in the integral circuit acts as an intermediary between the signal-collection line and the timing circuit. It converts the collected analog current signal into a voltage signal and provides isolation, preventing parasitic parameters in the signal-collection line from directly affecting the measurement accuracy while maintaining signal integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ADC circuit provides high conversion accuracy, enabling precise digital data for effective external electrical compensation and improving light-emission uniformity in AMOLED displays.
Implementation Method 1
an integral circuit including an operational amplifier OPAMP and an integral capacitor C... the operational amplifier OPAMP has a negative input terminal coupled to a signal-collection line S1 configured to collect an analog current signal... to generate a first output signal
Implementation Method 2
a comparator COMP configured to compare the first output signal with a second voltage Vref2 to generate a second output signal
Implementation Method 3
a timer 2 configured to start a timing operation when the operational amplifier OPAMP receives the analog current signal from the signal-collection line S1 and end the timing operation when the second output signal changes
Data Source
AI summary
The present application discloses an analog-to-digital conversion (ADC) circuit. The circuit includes an integral circuit including an operational amplifier and an integral capacitor. The circuit further includes a comparator and a timer. The operational amplifier includes a positive input terminal configured to receive a first voltage, a negative input terminal coupled to a signal-collection line configured to collect an analog current signal, and an output terminal configured to output a first output signal. The comparator is configured to compare the first output signal with a second voltage to generate a second output signal to the timer. The timer is configured to start a timing operation when the operational amplifier receives the analog current signal and end the timing operation when the second output signal changes. A binary data resulted from the timing operation characterizes a digital signal corresponding to the analog current signal.