Image-Reading Device Time-Division Multiplexing AFE Reduction
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Solution Overview
Problem
Conventional image-reading devices employing contact image sensors require multiple triple-channel analog front ends (AFE) and suffer from inefficiencies in data output speed due to non-sampling periods, especially when dealing with larger image reading areas.
Innovation Solution
An image-reading device with a plurality of image sensors, a starting signal generator, and a signal timing regulator, where the starting signal is generated at predetermined intervals, and the signal timing is regulated to ensure non-overlapping sampling periods, allowing for efficient image reading with fewer AFEs by using a single triple-channel A/D converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the image reading area increases, then the coverage area is improved, but the number of blocks and AFEs required increases
Solution Approach 1:
The patent implements periodic sampling action by dividing the image reading area into multiple blocks that are sampled at different time periods. Each block is read sequentially during different sampling periods within a single pixel reading period, allowing one AFE to handle multiple blocks through time-division multiplexing rather than requiring separate AFEs for each block
Solution Approach 2:
The patent adds a time dimension to the spatial arrangement of blocks. Instead of requiring spatial separation of AFEs for each block, the invention uses temporal separation by assigning different sampling periods to different blocks, effectively converting a spatial problem into a temporal solution that reduces the number of AFEs needed
2Adaptability or versatility
If multiple triple-channel AFEs are used to handle increased image reading area, then the image reading capability is improved, but the device cost and complexity increase
Solution Approach 1:
The patent makes a single triple-channel AFE universal by enabling it to process image signals from multiple blocks sequentially through time-division multiplexing. The AFE serves multiple functions by reading different blocks during different sampling periods, eliminating the need for dedicated AFEs for each block and reducing overall device complexity
Solution Approach 2:
The patent merges the functionality of multiple AFEs into a single AFE by combining the sampling operations of multiple blocks into one time-multiplexed system. The single AFE combines processing capabilities for all blocks through sequential sampling, reducing component count while maintaining image reading capability
3Ease of operation
If non-sampling periods are included in the single pixel reading period, then the sampling process is simplified, but the data output speed decreases
Solution Approach 1:
The patent eliminates non-sampling periods by continuously performing useful sampling actions throughout the entire pixel reading period. Each sampling period is tightly arranged without idle time, ensuring that the AFE continuously processes image data from different blocks without interruption, thereby maximizing data output speed while maintaining operational simplicity
Data Source
AI summary
An image-reading device includes a plurality of image sensors, a starting signal generator and a signal timing regulator. Each image sensor reads images on a pixel basis and generating an image signal indicative of the image. The image signal is an analog signal. The starting signal generator generates starting signals at every predetermined time period. A sampling period for sampling the image signal is set within the predetermined time period. In response to the starting signal sequentially inputted to the image sensors, the image sensors read the image until the predetermined time period is expired. The signal timing regulator delays an input timing at which the starting signal is inputted to the image sensor so that the sampling periods for the plurality of image sensors are different from one another.