How to counter frozen images in automotive displays

July 31, 2017 Majeed Ahmed, Automotive Contributor

High-resolution displays are the new norm in cars for infotainment, navigation, and instrument clusters, and chips are becoming available to ensure automotive-grade reliability for these increasingly larger and higher resolution displays.

Take the case of rearview cameras that stream live video onto full-display rearview mirrors. All new vehicles in the United States to be sold after May 2018 are required to have a rearview camera to prevent backover accidents. And these rearview cameras must display video in less than two seconds after the driver places the vehicle into reverse gear. That brings into question a critical issue in automotive display design: fast boot reliability.

Head-units often experience hang-ups caused by operating system (OS) software freezes, and that hampers rearview camera's ability to display live video. Intersil's new LCD video processor (Figure 1) claims to have eliminated this problem by monitoring the infotainment system-on-chip (SoC) and camera output. That way, the video processor can identify frozen images beforehand. The TW8844 processor triggers an interrupt signal if thresholds set for frozen and abnormal image detection are violated.

[Figure 1 | Intersil's LCD processor comes with the analog video decoder, two scalers, and MIPI-CSI2 SoC interface.]

The processor bypasses the SoC by decoupling the camera-to-display signal path from the rest of the infotainment system and instantly displays the rearview camera video and it ensures a smooth input switching between various input sources to avoid screen flicker.

The TW8844 processor features two input measurement engines to monitor input from the SoC and camera for frozen image diagnostics and it's complemented by an EEPROM-based fast boot that allows register programming without the need for an external microcontroller.

A smarter display driver

Rohm Semiconductor and its affiliate company Lapis Semiconductor have also unveiled a display driver chipset for automotive-grade LCDs. However, to counter frozen screens, Rohm has integrated a timing controller onto its LCD driver chipset to incorporate a fail-detection function for verifying infotainment chipset operation.

The chipset facilitates feedback on input signals to the LCD and warns about potential peeling or destruction of the LCD driver.

[Figure 2 | Rohm's display driver boasts circuitry for failure detection.]

Rohm's new chipset also integrates gamma correction IC, source driver, power management IC and gate driver for HD/FHD displays. These features — apart from verifying chipset operations — allow designers to easily configure the high-resolution LCDs.

Rohm claims that its chipset is the first one that supports functional safety for displays. The Japanese chipmaker is aiming this display driver chipset for side mirror and speedometer designs.

Majeed Ahmad is the former Editor-in-Chief of EE Times Asia. He is a journalist with an engineering background and two decades of experience in writing and editing technical content. He is also the author of six books on electronics: Smartphone, Nokia’s Smartphone Problem, The Next Web of 50 Billion Devices, Mobile Commerce 2.0, Age of Mobile Data, and Essential 4G Guide.

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