Pre-flash Time Adjusting Circuit for Image Sensors
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Solution Overview
Problem
Conventional image sensors in optical mice fix the pre-flash time, leading to inefficient power usage as they do not adapt to varying brightness levels, requiring longer pre-flash times for darker images and wasting power on brighter images.
Innovation Solution
A pre-flash time adjusting circuit with a switching module and storage capacitor that dynamically adjusts the pre-flash time based on image brightness by charging pixel units until base-emitter voltages of bipolar junction transistors reach a stable state, allowing the light-emitting unit to stop providing light once stability is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pre-flash time is fixed in conventional image sensors, then the circuit structure is simple, but the power consumption increases because the pre-flash time cannot be adapted to different brightness levels
Solution Approach 1:
The patent applies dynamics by making the pre-flash time adjustable rather than fixed. The light-emitting unit's working duration is dynamically controlled based on the brightness of image data, allowing the system to adapt to different lighting conditions and reduce power consumption when brightness levels are high.
Solution Approach 2:
The patent changes the parameter of pre-flash time from a fixed value to a variable that can be adjusted according to image brightness. By modifying the working duration parameter of the light-emitting unit based on detected brightness levels, the system optimizes power consumption while maintaining image quality.
2Reliability
If the pre-flash time is extended to capture darker image data, then the image quality improves, but the power consumption increases
Solution Approach 1:
The patent adjusts the pre-flash time parameter based on the brightness characteristics of the image data. For darker images requiring longer pre-flash times, the system extends the duration, while for brighter images, it reduces the duration, thereby optimizing the balance between image quality and power consumption.
Solution Approach 2:
The system dynamically adapts the light-emitting unit's working duration according to the actual brightness requirements. This dynamic adjustment ensures that the pre-flash time is optimized for each imaging scenario, improving image quality when needed while minimizing power consumption when not required.
3Use of energy by moving object
If the pre-flash time is reduced for brighter images, then the power consumption decreases, but the image quality may deteriorate if the time is too short
Solution Approach 1:
The patent employs feedback by detecting the brightness of image data and using this information to adjust the pre-flash time. The system continuously monitors brightness levels and adapts the light-emitting unit's working duration accordingly, ensuring optimal image quality while minimizing power consumption through intelligent control.
Solution Approach 2:
The system dynamically adjusts the pre-flash time based on real-time brightness detection. This dynamic adaptation ensures that the light-emitting unit operates for the precise duration needed to capture high-quality images of brighter scenes without wasting energy on unnecessarily long pre-flash periods.
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 approach reduces power consumption by up to 86% compared to conventional image sensors, as the pre-flash time is adjusted according to image brightness, optimizing energy use and image capture.
Implementation Method 1
A first end of the storage capacitor is coupled to the switching module, and a second end of the storage capacitor is coupled to ground. When the image sensing array senses a light beam, the switching module selectively connects the first switch and the storage capacitor, such that the storage capacitor starts to charge the first pixel units
Implementation Method 2
The feedback amplifier circuit 150 begins to build up a base-emitter voltage VBE of the BJT transistor Q to increase the beta of the BJT transistor Q to a stable state e.g., ~30. The beta herein is the ratio between the collector current IC and the base current IB of the BJT transistor Q
Implementation Method 3
The photodetector PD operatively generates a base current IB in responsive to a light intensity of the reflected light
Data Source
AI summary
The present disclosure illustrates a pre-flash time adjusting circuit. The pre-flash time adjusting circuit comprises a first pre-flash time adjusting unit coupled to an image sensing array. The image sensing array comprises a plurality of pixel units. The first pre-flash time adjusting unit comprises a switching module and a storage capacitor. When the image sensing array senses a light beam, the switching module selectively connects a first switch and the storage capacitor, such that the storage capacitor starts to charge the first pixel units of the first pixel group, until base-emitter voltages of a plurality of bipolar junction transistors disposed in the first pixel units reaches a stable state.