Power Circuit for LCDs Using Frequency Division and Boosting
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Solution Overview
Problem
Current low temperature polysilicon TFT-based liquid crystal display devices face challenges in shifting and dividing high-frequency, low-voltage signals, making it difficult to provide a stable power circuit that operates independently of voltage and frequency for the interface and display device.
Innovation Solution
A power circuit comprising a frequency dividing circuit, a boosting circuit, a level shifter, and a switching unit that complements the signals to achieve level conversion and frequency division, allowing for independent operation of the circuit block, including a DC-DC converter with a boosting pulse switching system to generate internal driving voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a low temperature polysilicon TFT-based power circuit is used to integrate driving circuits on the same substrate, then device integration and compactness are improved, but the ability to shift and divide high-frequency, low-voltage signals deteriorates
Solution Approach 1:
The power circuit is divided into separate functional blocks: a boosting circuit for voltage conversion, a frequency dividing circuit for signal processing, and a level shifter for signal level adjustment. Each block is optimized independently to perform its specific function, allowing the integrated circuit to handle high-frequency, low-voltage signals effectively while maintaining compact substrate area.
2Adaptability or versatility
If voltage level shifting is performed using conventional circuits, then compatibility with external interfaces is improved, but the threshold voltage increase at re-boosting causes instability in the power circuit
Solution Approach 1:
The boosting circuit performs voltage level shifting before signals are processed by the frequency dividing circuit and other downstream components. By pre-converting external interface signals to the appropriate voltage levels, the circuit avoids threshold voltage instability during subsequent boosting operations, ensuring stable power circuit operation while maintaining interface compatibility.
3Speed
If high-frequency, low-voltage signals are inputted directly to the power circuit, then interface speed is improved, but the circuit cannot provide stable operation due to inability to shift and divide signals
Solution Approach 1:
The frequency dividing circuit acts as an intermediary between the high-frequency input signals and the boosting circuit. It receives high-frequency, low-voltage signals, performs frequency division to generate appropriate clock signals, and passes these processed signals to subsequent stages. This intermediary function enables the circuit to handle high-speed interfaces while maintaining stable operation through proper signal conditioning.
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
This solution enables the provision of a stable, low-voltage, high-frequency interface for liquid crystal display devices, ensuring independent operation and efficient power management, thereby supporting the integration of low-voltage and high-frequency type interfaces in mobile terminals.
Implementation Method 1
a boosting circuit (165) driven by a source voltage (VDDI) to boost voltage according to a boosting pulse signal
Implementation Method 2
a frequency dividing circuit (164) driven by a source voltage (VDDI) to divide frequency of an input signal
Implementation Method 3
a level shifter (161) that shifts level of a signal by a boosted voltage output from the boosting circuit (165)
Data Source
AI summary
A power circuit includes: a frequency dividing circuit dividing the frequency of a first signal to which a level shift processing has been applied; a boosting circuit boosting the voltage according to an output signal from the frequency dividing circuit or a second signal having a lower frequency than that of the first signal as a boosting pulse; a level shifter; and a switching unit. The switching unit obtains a boosted voltage output from the boosting circuit after a boosting operation, performed by the boosting circuit having received the second signal, inputs the boosted voltage output to the level shifter such that the level shifter can execute level conversion of the first signal, and stops the boosting operation performed according to the second signal, thereafter inputting the level-shifted first signal to the boosting circuit via the frequency dividing circuit to obtain a final boosted voltage.