Vehicle Camera Exposure Control Using Timers to Reduce Hunting
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Solution Overview
Problem
Conventional exposure control devices for vehicle-mounted cameras experience hunting issues, leading to flickering on the display screen when external light illuminance changes rapidly, such as when entering a tunnel or traveling under an overpass, which is unpleasant for occupants.
Innovation Solution
An exposure control device for vehicle-mounted cameras that includes an illumination level determination unit, timers for different change modes, and an exposure level determination unit, which operates timers based on illuminance level changes to provide appropriate temporal hysteresis between illuminance and exposure levels, optimizing exposure control by stepwise changes rather than continuous adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If exposure control continuously adjusts exposure levels according to external light illuminance changes, then the exposure control responds quickly to illuminance variations, but hunting occurs and display screen flickering appears when entering tunnels or traveling under overpasses
Solution Approach 1:
The patent applies periodic action by using timers to create delayed, stepwise exposure level changes instead of continuous adjustments. When illuminance level changes are detected, the system activates corresponding timers that control the timing and sequencing of exposure level transitions, thereby reducing hunting and flickering while maintaining appropriate response to illuminance variations
Solution Approach 2:
The system performs preliminary action by predicting potential hunting situations based on current illuminance levels and their rates of change. The timer operating unit activates timers in advance based on the state of change of illuminance level, preparing the exposure control system to respond in a controlled manner before actual exposure adjustments are needed, thus preventing oscillations
2Reliability
If multiple timers are introduced for different change modes to control exposure level transitions, then hunting and flickering are reduced, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a timer operating unit that manages multiple timers through a unified control logic. The same timer management mechanism handles different change modes (increasing illuminance, decreasing illuminance, stable illuminance) by selecting appropriate timers based on the current illuminance change state, thereby reducing complexity compared to having separate control systems for each mode
Data Source
AI summary
An exposure control device of a vehicle-mounted camera comprises an illuminance level determination unit, a plurality of timers, a timer operating unit, and an exposure level determination unit. The illuminance level determination unit determines that an illumination level of an external light illuminance corresponds to one of a plurality of illuminance levels. The timers each provided for a corresponding one of a plurality of change modes, the change modes being defined among the plurality of illuminance levels, or among a plurality of exposure levels for an exposure of a vehicular camera. The timer operating unit operates each of the timers in accordance with a state of change of the illuminance level of the external light illuminance. The exposure level determination unit determines one of the exposure levels for the exposure of the vehicular camera based on a count state of each of the timers.