Pixel Anti-Overexposure Circuit With Capacitor-Based Exposure Cutoff
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Solution Overview
Problem
Conventional image capture devices face the challenge of overexposure, where near objects become over-exposed when trying to capture clear images of far objects, and vice versa, due to fixed exposure times.
Innovation Solution
An anti-overexposure circuit structure incorporating a photo diode, capacitors, and a control circuit that dynamically adjusts the exposure by switching off the first switch when the state of charge of the capacitors falls below a predetermined level, preventing overexposure by alternately discharging electricity from capacitors during illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exposure time is set long to capture far objects clearly, then far objects are clear, but near objects become over-exposed
Solution Approach 1:
The pixel array is divided into multiple pixel units, each independently equipped with capacitors and switches to implement local exposure control. This segmentation allows different regions to have different exposure characteristics, preventing over-exposure in specific areas while maintaining long exposure for distant objects.
Solution Approach 2:
The patent introduces dynamic exposure control through capacitors that can be switched during the exposure period. The state of charge of capacitors is monitored, and switches are dynamically adjusted to modulate the exposure time for individual pixel units, enabling adaptive exposure adjustment based on real-time charge levels.
2Measurement precision
If exposure time is set short to capture near objects clearly, then near objects are clear, but far objects become under-exposed
Solution Approach 1:
By dividing the pixel array into independently controllable pixel units with dedicated capacitors and switches, the system can apply different exposure durations to different spatial regions, optimizing near object capture without compromising far object visibility.
Solution Approach 2:
The patent changes the exposure time parameter dynamically for different pixel units based on their distance from the subject. Near objects receive shorter exposure times while far objects receive longer exposure, with the transition managed through capacitor charge level monitoring and switch control.
3Illumination intensity
If maximum exposure time is used to ensure all objects are visible, then image brightness is sufficient, but over-exposure occurs in some regions
Solution Approach 1:
The system dynamically monitors capacitor state of charge levels and adjusts switch states in real-time during the exposure period. This dynamic control prevents over-exposure by modulating the exposure duration for individual pixel units while maintaining overall image brightness through coordinated capacitor charging and discharging cycles.
Solution Approach 2:
The control circuit monitors the state of charge of capacitors and uses this feedback information to control the switching elements. When capacitors reach a predetermined charge level, the control circuit adjusts the switch state to prevent over-exposure, creating a closed-loop feedback system that maintains image quality consistency.
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 prevents overexposure, enhancing the quality of captured images and allowing for accurate distance measurement, even at maximum exposure times, by independently activating the anti-overexposure mechanism for each pixel unit, thereby improving image resolution and 3D surface representation.
Implementation Method 1
a photo diode, a first switch and a control circuit. The photo diode is coupled to the first capacitor and the second capacitor
Data Source
AI summary
An anti-overexposure circuit structure and an electronic device using the same are provided. An anti-overexposure circuit structure includes a first capacitor, a second capacitor, a photo diode, a first switch and a control circuit. The photo diode is coupled to the first capacitor and the second capacitor. The first switch is serially connected to the photo diode. The control circuit is coupled to the first switch and configured to: control the first switch to be turned off when SOC of the first capacitor or SOC of the second capacitor the SOC is lower than a predetermined level. As a result, it can prevent pixel unit of the electronic device from being overexposed.