Image Signal Serialization for Fast Scanning Over Flat Cables
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Solution Overview
Problem
Existing signal processing apparatuses for image reading devices face challenges in maintaining high-speed data transmission of image LVDS signals and clock LVDS signals over flexible flat cables, which suffer from signal degradation as cable length increases, making it costly to use dedicated cables for maintaining waveform quality.
Innovation Solution
A signal processing apparatus that converts six analog image signals into six 10-bit digital signals, then serializes them into four 10-bit signals, and further into six 7-bit serial signals, which are transmitted as low-voltage differential signals, reducing the transmission speed and mitigating signal degradation even with inexpensive flexible flat cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transfer rate of image LVDS signal is increased to achieve higher reading speed, then productivity is improved, but signal degradation becomes more severe due to use of flexible flat cable
Solution Approach 1:
The patent changes the data transmission parameters by converting 10-bit parallel data to 7-bit serial data, reducing the transmission frequency from 80 MHz to 40 MHz. This parameter change allows the use of flexible flat cable without severe signal degradation while maintaining high reading speed through efficient data serialization and memory buffering
2Reliability
If a dedicated cable optimized for LVDS transmission is used to maintain waveform quality, then reliability is improved, but device cost increases
Solution Approach 1:
The patent replaces the expensive dedicated LVDS cable with an inexpensive flexible flat cable by implementing data rate reduction through serialization. This allows the use of a cheaper cable alternative that would normally be inadequate for high-speed transmission, thereby reducing device cost while maintaining signal quality
3Productivity
If the frequency of analog image signal is increased to achieve higher reading speed, then productivity is improved, but the transfer rate of image LVDS signal must be increased leading to more severe signal degradation
Solution Approach 1:
The patent transitions from parallel data transmission (10-bit width at 40 MHz) to serial data transmission (7-bit width at 40 MHz after serialization), effectively changing the dimension of data flow. This dimensional change allows maintaining high reading speed while reducing the frequency requirements for LVDS transmission, thereby minimizing signal degradation
Data Source
AI summary
Provided is a signal processing apparatus that enables an image reading apparatus to perform higher speed processing of reading a document image. A signal processing unit is configured to convert six analog image signals obtained from a line sensor into six first signals, each of which is a 10-bit digital image signal, respectively, and to write the six first signals into a RAM at a first speed that is the same as a frequency of the analog image signals. The signal processing unit is configured to cause a serialization unit to read out from the RAM the six first signals as four second signals, each of which is a 10-bit digital image signal, at a second speed higher than the first speed, respectively, and to serialize the four second signals to generate six 7-bit serial signals.