Video Switch Asynchronous I2C TMDS Signal Control
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Solution Overview
Problem
Conventional video switching methods result in significant delays and undesirable blank screens during image switching due to HDCP authentication and EDID reading processes, taking around 4 to 2 seconds for lower and higher end televisions respectively, causing long delays and poor viewer experience.
Innovation Solution
A video switch employing asynchronous switching of I2C and TMDS signals using a first and second switch unit, coupled with a microcontroller unit, which maintains video output by switching I2C signals first and then TMDS signals, reducing switching time to approximately 0.3 to 1 second and preventing blank screens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional video switching method is used with HDCP authentication and EDID reading, then security protection and device identification are ensured, but image switching time becomes too long (1-4 seconds) and blank screen occurs
Solution Approach 1:
The patent performs HDCP authentication and EDID reading in advance before the user actually switches channels. The microcontroller unit pre-authenticates the next channel's HDCP security and pre-reads its EDID information during the current channel's display, so when switching is triggered, these time-consuming operations have already been completed, eliminating the 1-4 second delay and preventing blank screens
2Device complexity
If synchronous switching of I2C and TMDS signals is used, then switching control is simple, but blank screen occurs during switching and switching time is extended
Solution Approach 1:
The patent separates the switching control into two independent parts: I2C signal switching (for control data) and TMDS signal switching (for video data). The microcontroller unit first switches the I2C signal to the next channel, then after a predetermined time delay allowing authentication and EDID reading to complete, switches the TMDS signal. This segmentation prevents blank screens while keeping control logic manageable through timing coordination
Data Source
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AI summary
The present invention provides a video switch and a switching method thereof. The video switch comprises a first input port configured to transmit a first Transition Minimized Differential Signaling (TMDS) and a first Inter-Integrated Circuit (I2C) signal; a second input port configured to transmit a second Transition Minimized Differential Signaling (TMDS) and a second Inter-Integrated Circuit (I2C) signal; a first switch unit and a second switch unit. When switching the first input port to the second input port, the video switch firstly outputs the second Inter-Integrated Circuit (I2C) signal a specific time and then outputs the second Transition Minimized Differential Signaling (TMDS).