Image Sensor Power Control for Shading Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image reading apparatuses face degradation in image quality due to temperature fluctuations affecting the sensitivity of light-receiving elements in image sensors, which existing technologies attempt to address through complex circuits to stabilize temperature, but these solutions increase size and cost.
Innovation Solution
An image reading apparatus with a power consumption controller that adjusts the power usage of the image sensor to stabilize temperature by driving it at a higher power during preparation and a lower power during reading, allowing for effective shading correction without the need for a large-scale circuit to detect output levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-scale circuit is used to detect the output level of the image sensor in real time, then image quality degradation due to temperature fluctuation can be suppressed, but the size and cost of the apparatus increase
Solution Approach 1:
The patent replaces the mechanical/electrical detection system (large-scale circuit for real-time output level detection) with a optical-based solution. A test chart with known reflectance characteristics is imaged by the image sensor, and the output is processed to detect temperature-induced sensitivity changes. This substitution eliminates the need for complex real-time detection circuits while achieving the same temperature compensation goal.
Solution Approach 2:
The patent uses a test chart (copy of a known reference pattern) to indirectly measure the image sensor's temperature characteristics. Instead of directly monitoring the sensor's output level with complex circuits, the system captures an image of the test chart and compares it against reference data to detect temperature drift. This copying approach simplifies the detection mechanism while maintaining accuracy.
2Reliability
If the image sensor is driven with high power consumption to stabilize temperature, then sensitivity variation due to temperature fluctuation is reduced, but energy consumption increases
Solution Approach 1:
The patent implements periodic temperature compensation by capturing images of a test chart at regular intervals (e.g., every 10 seconds) rather than continuously monitoring with high power consumption. The image sensor operates at normal power levels between measurements, and temperature drift is corrected periodically using the test chart data. This periodic action maintains temperature stability while significantly reducing average power consumption compared to continuous high-power operation.
Solution Approach 2:
The patent changes the operational parameters of the image sensor dynamically. During normal operation, the sensor runs at standard power consumption. When temperature compensation is needed, the system captures test chart images and adjusts the sensitivity correction parameters based on detected temperature drift. This parameter change approach allows the sensor to maintain accuracy without sustained high power consumption.
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 effectively suppresses image quality degradation caused by temperature fluctuations while reducing the apparatus's size and cost by eliminating the need for a large-scale circuit to monitor output levels.
Implementation Method 1
an image sensor configured to receive light reflected on the original and output an image signal representing an original image of the original
Implementation Method 2
drive the image sensor with a first power consumption during a preparation period before the controller causes the image sensor to read the reference member and thereafter drive the image sensor with a second power consumption smaller than the first power consumption
Data Source
AI summary
An image reading apparatus includes: a reading unit configured to read an image of an original and output an image signal; and a white reference plate to be used for shading correction. The image reading apparatus drives the reading unit with maximum power consumption for a predetermined time period and thereafter drives the reading unit with reduced power consumption. The image reading apparatus causes the reading unit with reduced power consumption to read the white reference plate and generates shading data to be used for the shading correction. After that, the image reading apparatus causes the reading unit to read an original and corrects a reading result of the original based on the shading data.