Image Reading Apparatus Sampling Timing Adjustment
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Solution Overview
Problem
The accuracy of image reading in image reading apparatuses is reduced due to variations in output time caused by the position of pixels and temperature changes in CMOS image sensors, leading to unstable sampling of analog image signals.
Innovation Solution
An image reading apparatus that includes a temperature detector, a sampling unit that adjusts sampling timing based on detected temperature, and a converter to generate stable digital image data by synchronizing sampling with the output amplifier's temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the output amplifier is arranged at an end of the CMOS image sensor in the main scanning direction to reduce device complexity, then the sampling timing becomes unstable due to varying output times from different pixel positions, but this arrangement simplifies the device structure
Solution Approach 1:
The patent applies preliminary action by calculating and storing the output time for each pixel position in advance, based on the distance from each pixel to the output amplifier. During operation, the AFE uses these pre-calculated values to determine the appropriate sampling timing for each pixel, ensuring stable sampling without requiring complex real-time calculations or changing the physical amplifier arrangement.
2Ease of operation
If the sampling timing is fixed to simplify operation, then the analog image signal may be sampled at unstable signal levels due to temperature variations, but fixed timing simplifies the operation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the sampling timing parameter based on temperature variations. The system detects temperature changes and modifies the sampling timing accordingly, using pre-calculated output time values that account for temperature effects. This allows the operation to remain simple while adapting to environmental conditions to maintain sampling stability.
3Measurement precision
If the sampling timing is adjusted for each pixel position to improve measurement precision, then the device complexity increases due to additional control mechanisms, but sampling accuracy improves
Solution Approach 1:
The patent reduces device complexity by performing the complex calculation work in advance. The output times for all pixel positions are pre-calculated and stored in a lookup table during system initialization or manufacturing. During actual operation, the AFE simply retrieves the appropriate pre-calculated value based on the current pixel position and temperature, avoiding the need for complex real-time computation hardware or sophisticated control mechanisms.
4Ease of manufacture
If the AFE samples the analog image signal at predetermined periods to simplify the conversion process, then the sampling may occur at unstable signal levels due to temperature characteristics, but predetermined sampling simplifies the conversion process
Solution Approach 1:
The patent applies parameter changes by modifying the sampling timing parameter based on temperature conditions while maintaining the overall predetermined sampling approach. The system detects temperature variations and adjusts the sampling timing offset accordingly, using pre-calculated correction values. This allows the conversion process to remain simple and predetermined in structure while adapting the timing parameter to compensate for temperature effects, ensuring accurate sampling without complicating the manufacturing or conversion process.
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 ensures accurate sampling and conversion of analog image signals, thereby enhancing the stability and accuracy of image reading by adjusting sampling timing according to temperature variations, reducing errors caused by pixel position and temperature changes.
Implementation Method 1
The image reading apparatus reads an original image by irradiating an original with light emitted from a light source and reading reflected light with an image sensor
Implementation Method 2
the amplifier being configured to amplify an analog signal corresponding to results of receiving the light by the plurality of light-receiving elements included in the line sensor
Implementation Method 3
a detector configured to detect a temperature of the reading device
Implementation Method 4
a converter configured to convert the value sampled by the sampling unit into a digital value
Data Source
AI summary
An image reading apparatus includes a light emitter configured to irradiate an original with light, a reading device including a line sensor and an amplifier, a detector configured to detect a temperature of the reading device, a sampling portion configured to sample a value of the analog signal output from the amplifier, a converter configured to convert the value sampled by the sampling portion into a digital value. The sampling portion is configured to sample the analog signal corresponding to a first light-receiving element included in the plurality of light-receiving elements at a first timing in a case where the temperature detected by the detector is a first temperature, and to sample the analog signal corresponding to the first light-receiving element at a second timing, which is later than the first timing.