Level Setting Circuit for Flat Display Standby Power Reduction
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Solution Overview
Problem
In liquid crystal display apparatuses, the deep standby mode fails to completely shut off power supply voltages, leading to increased size and power consumption due to through-currents between circuit blocks with different power supply voltages, especially when transitioning from 6V to 3V.
Innovation Solution
A configuration where a first circuit block operates at a higher power supply voltage and a second circuit block processes results from the first, with active elements performing on-off operations complementarily to prevent through-currents, and a level setting circuit maintains the output at a predetermined level as the higher power supply voltage falls, allowing complete power reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage is completely shut off in deep standby mode, then power consumption is reduced, but the configuration becomes complicated and the device size increases
Solution Approach 1:
The level setting circuit preliminarily adjusts the output level of the first circuit block before the power supply voltage falls, ensuring that the active elements in the second circuit block are already in the correct state to prevent through-currents when power is reduced. This preliminary action allows the system to achieve complete power shutdown without requiring complex additional control configurations.
2Loss of energy
If the power supply voltage falls from 6V to 3V, then through-currents are prevented, but leak currents continue to flow and power consumption is not fully reduced
Solution Approach 1:
The invention changes the parameter of power supply voltage from a fixed 6V or 3V to a dynamically controllable parameter that can fall to 0V. By controlling the power supply voltage to completely fall rather than merely transitioning between voltage levels, the system eliminates both through-currents and leak currents, achieving complete power consumption reduction in standby mode.
3Loss of energy
If active elements operate with complementarily on-off operation, then through-currents are prevented, but the output level may become unstable when power supply voltage falls
Solution Approach 1:
The level setting circuit acts as an intermediary between the first circuit block and the active elements. It mediates the transition by controlling the output level of the first circuit block to ensure that when the power supply voltage falls, the active elements maintain stable output levels and remain in the correct state, preventing both through-currents and output instability.
Data Source
AI summary
The present invention is applied, for example, to a liquid crystal display apparatus in which drive circuitry is formed integrally on an insulating substrate, wherein processing results from circuit blocks 41A, 41B on the side of a higher power supply voltage are inputted into the side of a lower power supply voltage through active elements performing on-off operation complementarily, and by the fall of the power supply voltage on this higher side, the output of these active elements is set to a predetermined level.