Front-Back Image Inspection Timing for Sheet Edge Alignment
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Solution Overview
Problem
Existing image inspection systems struggle to accurately align front and back images of a medium due to variations in timing of sheet edge detection, especially when the CPU is congested, leading to misalignment of images captured by different capturing units.
Innovation Solution
The system employs a capturing-signal generator that generates a second capturing-image signal for the second capturing unit after a predetermined time has elapsed since the first capturing unit captures the first image, using a hardware clock or real-time OS to minimize timing variations, and incorporates background members with distinct colors to enhance edge detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If polling processing by CPU is used to detect sheet edge, then device complexity is reduced, but timing variation increases leading to image misalignment
Solution Approach 1:
The patent replaces the software-based polling mechanism with a hardware-based interrupt system. The photosensors generate hardware interrupts directly to the CPU when sheet edges are detected, eliminating the need for continuous polling loops. This substitution of mechanical/control approach ensures precise timing capture without CPU congestion, resolving the contradiction between simplified device structure and timing precision.
Solution Approach 2:
The photosensors autonomously generate interrupt signals when detecting sheet edges, without requiring CPU initiation or polling. This self-service mechanism allows the detection system to operate independently of CPU scheduling, ensuring consistent timing precision while maintaining device simplicity. The system serves itself by having the sensors trigger the detection process rather than the CPU actively querying them.
2Adaptability or versatility
If separate photosensors are provided for front and back surfaces, then image capture capability is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal photosensor design where a single photosensor model and detection mechanism serves both front and back surface detection functions. The same photosensor type detects sheet edges on both surfaces, and the same interrupt-based processing logic handles both surfaces. This multi-functionality approach maintains image capture versatility while minimizing device complexity by avoiding duplication of specialized components.
3Ease of operation
If CPU polling is used for sheet edge detection, then ease of operation is maintained, but productivity decreases due to processing delays
Solution Approach 1:
The patent transitions from periodic polling action to event-driven interrupt action. Instead of the CPU periodically checking for sheet edges at fixed intervals, the system now responds immediately when edge detection events occur. This event-driven approach eliminates unnecessary periodic checks, accelerates processing by responding only when needed, and maintains operational simplicity through the standardized interrupt handling framework.
Data Source
AI summary
;d;s;w;s;f;h;f;a;302An image inspection apparatus includes: a first capturing unit to capture a first image of one surface of a medium; a second capturing unit to capture a second image of the other surface of the medium; and a capturing-signal generator to generate a second capturing-image signal for causing the second capturing unit to capture the second image after a predetermined time has elapsed since a first start-capturing-image signal for causing the first capturing unit to capture the first image.