Level Shifter Pseudo-Signal Control for Overlap EMI Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices face challenges in completely offsetting electromagnetic interference (EMI) during overlapping sections of driving signals, which can occur due to the phase inversion of signals not adequately addressing the interference in these overlapping periods.
Innovation Solution
A level shifter is designed with a driving signal generation circuit and a pseudo signal generation circuit. The pseudo signal generation circuit generates phase-inverted pseudo signals that reflect the transitions of all analog driving signals, and adjusts the voltage level of these pseudo signals based on the driving signals' transitions during overlapping sections, effectively offsetting the electric field and reducing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If phase-inverted pseudo signals are output to offset EMI, then electromagnetic interference reduction is improved, but EMI in overlapping sections cannot be completely offset
Solution Approach 1:
The patent applies dynamics by making the pseudo signal voltage level adjustable rather than fixed. The pseudo signal generation circuit dynamically changes the voltage level of pseudo signals based on whether driving signals are in an overlapping section, allowing the system to adapt to different operational conditions and achieve complete EMI offset even in overlapping sections
Solution Approach 2:
The patent changes the voltage level parameter of pseudo signals dynamically. When driving signals overlap, the pseudo signal voltage level is adjusted to a second level that differs from the first level used when signals do not overlap. This parameter change enables effective EMI cancellation in overlapping sections where fixed-level pseudo signals would fail
2Object-affected harmful factors
If voltage level of pseudo signals is adjusted during overlapping sections, then EMI offset effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent merges the voltage level adjustment function into the existing pseudo signal generation circuit rather than adding a separate control system. The pseudo signal generation circuit integrates both pseudo signal generation and dynamic voltage level adjustment capabilities, reducing overall device complexity while achieving effective EMI offset
Solution Approach 2:
The pseudo signal generation circuit is designed to perform multiple functions: generating phase-inverted pseudo signals and dynamically adjusting their voltage levels based on driving signal overlap conditions. This multi-functionality eliminates the need for separate dedicated circuits, maintaining device simplicity while solving the EMI offset problem
3Object-affected harmful factors
If pseudo signals are generated to reflect all driving signal transitions, then EMI offset effectiveness is improved, but the number of pins increases
Solution Approach 1:
The patent uses a single pseudo signal line to carry pseudo signals that encode information about all driving signal transitions. Instead of creating separate pseudo signal lines for each driving signal, the system creates one comprehensive pseudo signal that reflects the collective state of all driving signals, maintaining the pin count while achieving complete EMI coverage
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 effectively offsets the electric field of the analog driving signals even when all signals overlap, reducing EMI in proportion to the signal intensity, and does so without increasing the number of pins on the level shifter.
Implementation Method 1
a pseudo signal generation circuit configured to generate phase-inverted pseudo signals of the driving signals
Implementation Method 2
signals having phases that are inverted to phases of the driving signals are output together to offset the EMI
Data Source
AI summary
A level shifter according to an embodiment and a display device using the same are discussed. The level shifter includes a driving signal generation circuit configured to output driving signals through signal lines, and a pseudo signal generation circuit configured to generate phase-inverted pseudo signals of the driving signals. The pseudo signal generation circuit can raise or lower a voltage level of the pseudo signals by a variation magnitude adjusted according to the driving signals whenever a section with the driving signals overlapping on a time axis occurs.