Image Pickup Device Shutter Pulse Control for Noise Prevention
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Solution Overview
Problem
Image pickup apparatuses face noise generation issues when trying to elongate exposure time or shorten the cycle of the external trigger pulse, particularly in industrial applications, due to the complexity of controlling the shutter pulse within narrow blanking periods and synchronizing signals.
Innovation Solution
A driving control method for an image pickup device that synchronizes the read-out pulse with the horizontal synchronizing signal and generates the shutter pulse during every horizontal blanking period except for the period from the external trigger pulse generation to the read-out pulse, allowing for selection between two shutter pulses to prevent noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the external trigger pulse TRIG is generated within the output period t3 of the image signal to enable slow shutter (long exposure time), then the exposure time is elongated, but noise 20 is generated in the displayed image
Solution Approach 1:
The patent extracts the harmful operation (shutter pulse generation) from the period when image signals are being output. By generating shutter pulses only during horizontal blanking periods and excluding the period from trigger pulse to read-out pulse, the harmful effect of noise is eliminated while preserving the useful function of exposure control.
Solution Approach 2:
The patent performs preliminary timing arrangement by pre-defining the shutter pulse generation window to occur only during horizontal blanking periods. This preliminary action ensures that shutter operations are completed before image signal output begins, preventing noise generation while maintaining the desired exposure duration.
2Productivity
If the cycle of the external trigger pulse TRIG is shortened to reduce inspection time and increase belt conveyor speed, then productivity is improved, but noise 20 is generated in the displayed image
Solution Approach 1:
The patent removes the harmful shutter pulse generation from the image signal output period. By confining shutter operations to horizontal blanking periods only, the system can handle short-cycle trigger pulses without generating noise, thus enabling high-speed operation.
Solution Approach 2:
The patent utilizes the periodic horizontal blanking periods of the video signal as designated windows for shutter pulse generation. This periodic structure provides regular, noise-free opportunities to reset the image sensor without interfering with continuous image signal output, enabling high-speed triggering.
3Object-affected harmful factors
If the external trigger pulse TRIG is controlled to be generated within the narrow blanking period t3 to prevent noise, then noise is prevented, but the device structure becomes complicated and control becomes difficult
Solution Approach 1:
The patent makes the horizontal blanking period serve multiple functions: it acts as both the synchronization interval for video signals and the designated window for shutter pulse generation. This multi-functionality eliminates the need for separate noise-prevention mechanisms while maintaining image quality.
Solution Approach 2:
The video signal's own horizontal blanking periods provide the necessary time windows for noise-free shutter operation. The system uses its existing synchronization structure to automatically prevent noise without requiring additional control complexity or external intervention.
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 method effectively prevents noise in the output image regardless of exposure time and trigger pulse cycle, simplifying the system by not requiring precise timing control within the blanking period, and enables elongation of exposure time and shortening of the trigger pulse cycle.
Implementation Method 1
electric charges obtained by photoelectric conversion of incident light from an object
Data Source
AI summary
The present invention enables prevention of influence of a trigger pulse in an image from an image pickup apparatus, with a simple structure and irrespective of exposure time and the cycle of the trigger pulse. The present invention provides an image pickup apparatus having a CCD image sensor 202 in which electric charges obtained by photoelectric conversion of incident light from an object are stored, the stored electric charges are swept away when a shutter pulse SUB is supplied, and after a read-out pulse SG is supplied, an image pickup signal based on the stored electric charges is read out synchronously with a horizontal synchronizing signal HD, and the image pickup apparatus comprises a timing generator 212 for generating the read-out pulse during a blanking period of the horizontal synchronizing signal, first shutter pulse generation means 310 for generating a first shutter pulse sub1 during every horizontal blanking period of the horizontal synchronizing signal except for a period from generation of a trigger pulse TRIG until generation of the read-out pulse, second shutter pulse generation means 320 for generating a second shutter pulse sub2 at the timing of the trigger pulse, and a switch 330 for selecting either the first shutter pulse sub1 or the second shutter pulse sub2.