Image Reading Apparatus Phase and Signal Level Correction
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Solution Overview
Problem
Conventional image reading apparatuses experience color shifting due to the sequential emission of red, green, and blue light at different positions on the sheet, leading to incorrect color representation in the read image.
Innovation Solution
An image reading apparatus with a light source that emits red, green, and blue light at predetermined intervals, accompanied by a line-to-line correction and signal level correction mechanism to align and stabilize the signal waveforms, ensuring accurate color representation by correcting phase shifts and signal level differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light source moves in the sub-scanning direction and sequentially switches among red, green and blue light to emit light of different colors to the sheet at different times, then the reading speed is improved, but color shifting occurs because light of different colors is irradiated onto different positions of the sheet
Solution Approach 1:
The patent applies preliminary action by measuring the actual position of the light source at the moment of light emission and using this information to correct the phase of the electric signal before image reconstruction. The phase correction amount is calculated in advance based on the light source position and sub-scanning speed, allowing the color shift to be compensated before the final image is generated, thus maintaining both high reading speed and color accuracy
Solution Approach 2:
The patent implements feedback by continuously monitoring the light source position and using this feedback to dynamically adjust the phase correction amount for each color channel. The system measures the light source position, calculates the corresponding phase shift, and applies the appropriate correction to each color signal, creating a closed-loop control system that maintains color accuracy while enabling high-speed sequential color emission
2Manufacturing precision
If the phase of the electric signal is corrected to correct the color shift, then color shifting is reduced, but the color of the image changes because the signal level difference among color signals is not corrected
Solution Approach 1:
The patent merges phase correction and signal level correction into a unified correction process. Both corrections are applied to each color channel's electric signal before the signals are combined to generate the final color image. This integrated approach ensures that both the positional misalignment (phase shift) and the intensity differences (signal level) are corrected simultaneously, preventing color distortion while maintaining accurate color representation
Solution Approach 2:
The patent introduces signal level correction as an intermediary step between phase correction and image generation. After the phase correction aligns the color signals spatially, the signal level correction adjusts the intensity of each color channel to match the actual reflected light levels. This intermediary correction prevents color distortion by ensuring that the relative intensities of red, green, and blue signals accurately represent the original image colors
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
The apparatus effectively reduces color shifting and maintains accurate color representation by synchronizing the signal waveforms, resulting in a stable and corrected image output.
Implementation Method 1
a light source configured to repeatedly emit first light having a first color, second light having a second color and third light having a third color at different times toward a read target while moving the light source in a first direction, first, second, and third sensors, each configured to sense a strength of first, second, and third reflected light, respectively
Implementation Method 2
first, second, and third sensors, each configured to sense a strength of first, second, and third reflected light, respectively, in a light reflected from the read target, and to output first, second, and third signal waveforms
Data Source
AI summary
An image reading apparatus comprises a light source for repeatedly emitting first light having a first color, second light having a second color and third light having a third color toward a read target while moving the light source in a sub-scanning direction, first, second, and third sensors, each configured to sense a strength of first, second, and third reflected light, respectively, in a light reflected from the read target, and to output first, second, and third signal waveforms corresponding to the strength of the first, second, and third reflected light, respectively, and a controller. The controller is configured to execute a line-to-line correction for correcting a phase shift between the first, second, and third signal waveforms, and to correct a shift in a signal level caused by the line-to-line correction.