Projection Image Pickup Device Ambient Light Saturation
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Solution Overview
Problem
Conventional projection image pickup devices suffer from signal saturation when exposed to powerful ambient light, which disrupts proper image capture.
Innovation Solution
A projection image pickup device and method that utilize a pulsed-light emitter, optical sensor, reference timing generator, and signal processor to control exposure periods, including turning off the pulsed-light emitter during the first exposure, emitting light in synchronization during the second exposure, and emitting light with a delayed timing during the third exposure, calculating differential signals to isolate the reflected light component and reduce background light influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical sensor continuously exposes to ambient light, then the image pickup can capture general scene information, but the signal saturates when powerful ambient light enters, disabling proper image pickup
Solution Approach 1:
The patent applies periodic action by dividing the exposure into multiple periods within one frame: a first exposure period without pulsed light, and second and third exposure periods with synchronized pulsed light. This periodic structure allows the system to collect background light information separately from the projected light information, preventing saturation while maintaining reliable image pickup capability.
Solution Approach 2:
The patent segments the image pickup process into distinct exposure periods with different lighting conditions. By separating the capture of ambient light (first exposure) from projected light reflections (second and third exposures), the system can process and subtract background components, eliminating saturation effects while preserving reliable scene capture.
2Measurement precision
If the pulsed-light emitter emits light continuously, then the reflected light signal strength increases, but the background light influence and signal saturation increase simultaneously
Solution Approach 1:
The pulsed-light emitter operates periodically rather than continuously, emitting light only during the second and third exposure periods. This periodic emission synchronizes with the exposure timing, ensuring strong reflected light signals are captured when needed while minimizing background light accumulation that causes saturation.
Solution Approach 2:
The system maintains continuous useful action by ensuring the pulsed light emits precisely when the optical sensor is exposed during the second and third periods. This synchronization maximizes the captured reflected light signal strength while the first exposure period without pulsed light continuously captures background information for subtraction, eliminating both saturation and signal weakness.
3Measurement precision
If multiple exposure periods are implemented within one frame, then the background light can be separated and subtracted, but the frame time increases
Solution Approach 1:
The patent implements partial action by performing background light separation through multiple exposure periods within a single frame rather than requiring separate frames. The first exposure period captures background information that is then subtracted from the second and third exposures, achieving precise background removal without the time loss of extended framing.
Solution Approach 2:
The system merges multiple functions into a single frame structure: background light capture (first exposure), reflected light capture with pulsed synchronization (second exposure), and delayed reflected light capture (third exposure). By combining these functions sequentially within one frame, the patent achieves precise background separation while minimizing time loss compared to using separate frames for each function.
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
Effectively reduces the impact of powerful ambient light, preventing signal saturation and enhancing image quality by isolating the reflected light component.
Implementation Method 1
a pulsed-light emitter that emits light according to light emission control of the controller
Implementation Method 2
an optical sensor that is exposed according to the exposure control of the controller and outputs an output signal indicating an amount of exposure
Data Source
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AI summary
A projection image pickup device (100) includes a pulsed-light emitter (102), an optical sensor (104), a reference timing generator (108) that generates a signal indicating an operation reference timing, a controller (110), and a signal processor (106). The signal processor (106) sets a differential signal between an output signal from the optical sensor (104) in the second exposure period and an output signal from the optical sensor (104) in the first exposure period as a first differential signal, sets a differential signal between an output signal from the optical sensor (104) in the third exposure period and the output signal from the optical sensor (104) in the first exposure period as a second differential signal, and outputs the sum total of at least two differential signals including the first differential signal and the second differential signal.