Image Reading Apparatus Pixel Readout Control
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Solution Overview
Problem
Conventional image reading apparatuses are inefficient in reading required pixels, leading to suboptimal processing times and throughput.
Innovation Solution
The image reading apparatus adjusts the readout start and end pixels based on document size, employing a CMOS linear sensor and a readout control unit to change the line sync signal period, thereby reducing unnecessary pixel reading and optimizing line period for efficient data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all pixel data is sequentially outputted pixel by pixel in the main-scanning direction, then complete image data can be obtained, but reading time and processing time are excessively long
Solution Approach 1:
The pixel sensors are divided into first half portions and second half portions in the main scanning direction. The transfer circuit segments the data output process by reading from both halves simultaneously and outputting their data in parallel, thereby halving the reading time while maintaining complete image data acquisition.
2Productivity
If data from the joint portion is outputted as first data to enable immediate image processing, then throughput time is shortened, but data processing complexity increases
Solution Approach 1:
The transfer circuit performs preliminary action by outputting data from the joint portion between the first and second half portions as first data before the main scanning is complete. This enables image processing to start earlier on the joint portion without waiting for the entire scanning process, thereby reducing throughput time.
3Measurement precision
If the reading range covers the entire document, then all document content is captured, but unnecessary pixels are read increasing processing time
Solution Approach 1:
The reading system applies local quality by adjusting the readout start and end pixels based on document size. Instead of uniformly reading all pixels across the entire sensor range, the system locally adapts the reading boundaries to match the actual document dimensions, thereby eliminating unnecessary pixel readings and improving processing efficiency.
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 approach allows for faster reading times by reducing the line period by a factor of the square root of 2 when reading documents of different sizes, improving productivity without reading unnecessary pixels.
Implementation Method 1
charges accumulated by allowing light-receiving elements such as a plurality of photodiodes to receive light
Data Source
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AI summary
An image reading apparatus includes: light-receiving elements (300) arranged in a main-scanning direction to perform photoelectric conversion pixel by pixel; AD converter units (304) that convert each piece of analog data photoelectric-converted by the light-receiving elements (300) into parallel pieces of digital data; a storage unit (32) that stores therein each of the digital data converted by the AD converter units (304); a converter unit (34) that reads the digital data stored in the storage unit (32) and converts the read digital data into serial data in the main-scanning direction; a readout control unit (38) that changeably controls a readout start pixel and a readout end pixel of the serial data in the main-scanning direction; and a period change unit (360) that changes a period in which the converter unit (34) converts digital data into serial data in the main-scanning direction based on the readout start pixel and the readout end pixel.