Scan Line Driver Bootstrap Circuit for Low-Power Active Matrix Displays
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Solution Overview
Problem
In active matrix display devices, the increased number of scan lines and signal lines leads to higher power consumption, and existing techniques struggle to supply sufficient amplitude to scan lines while minimizing power consumption and signal distortion.
Innovation Solution
A semiconductor device with a scan line driver circuit that includes transistors and capacitors, using a light-transmitting conductive layer for the pixel electrode, gate electrode, source, and drain electrodes, and scan lines, enabling bootstrap operation to supply sufficient signal amplitude with reduced power consumption and minimizing signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of scan lines and signal lines is increased to achieve high definition and larger display size, then display quality and size are improved, but power consumption is increased
Solution Approach 1:
The scan line driver circuit is divided into multiple segments, each controlling a specific group of scan lines. This segmentation allows independent control and optimization of power consumption for different display regions, enabling the display to maintain high definition while reducing overall power consumption by activating only necessary segments.
Solution Approach 2:
The patent implements periodic scanning of display lines rather than continuous activation. By sequentially activating scan lines in periodic intervals and using refresh mechanisms, the display maintains high definition quality while significantly reducing power consumption compared to simultaneous activation of all lines.
2Use of energy by moving object
If the amplitude of scan line selection signal is reduced by the threshold voltage of the transistor, then power consumption is reduced, but signal distortion occurs and rising/falling times are prolonged
Solution Approach 1:
The patent introduces a bootstrap capacitor as an intermediary element between the scan line driver circuit and the scan lines. This capacitor stores and releases energy to compensate for the voltage drop caused by the transistor threshold voltage, ensuring that sufficient signal amplitude is maintained without increasing power consumption, thus preserving signal integrity while avoiding the threshold voltage penalty.
Solution Approach 2:
The patent dynamically changes the voltage parameters of the scan line selection signal by utilizing the bootstrap mechanism. The signal voltage is boosted during the selection period and then reduced during non-selection periods, allowing the system to maintain signal integrity when needed while minimizing power consumption during idle periods.
Data Source
AI summary
It is an object to provide a semiconductor device which can supply a signal with sufficient amplitude to a scan line while power consumption is kept small. Further, it is an object to provide a semiconductor device which can suppress distortion of a signal supplied to the scan line and shorten a rising time and a falling time while power consumption is kept small. A semiconductor device which includes a plurality of pixels each including a display element and at least one first transistor and a scan line driver circuit supplying a signal for selecting the plurality of pixels to a scan line. A light-transmitting conductive layer is used for a pixel electrode layer of the display element, a gate electrode layer of the first transistor, source and drain electrode layers of the first transistor, and the scan line. The scan line driver circuit includes a second transistor and a capacitor for holding a voltage between a gate electrode layer of the second transistor and a source electrode layer of the second transistor. The source electrode of the second transistor is connected to the scan line.