Image Density Control in Image Forming Apparatus via Dual-Sensor Calibration
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately controlling image density due to environmental conditions and developer degradation, requiring calibration processes that can be complex and disruptive to operations.
Innovation Solution
An image forming apparatus with an image carrier, image forming unit, transfer unit, reader, sensor, and controller that forms and reads pattern images on both the image carrier and sheet, allowing for continuous operation and precise control of image density by generating image forming conditions based on measured data from both sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed by reading test images on an image carrier before transfer, then image density control accuracy is improved, but the image forming operation must be interrupted and downtime increases
Solution Approach 1:
The patent applies preliminary action by forming test images on the image carrier before the transfer process, allowing density measurement to be prepared in advance. The controller forms test images including a first test image and a second test image on the image carrier, enabling subsequent density measurement without interrupting the main image forming operation.
Solution Approach 2:
The patent implements continuity of useful action by integrating test image formation into the ongoing image forming process. The image forming unit continues to form images on sheets while the controller simultaneously forms test images on the image carrier, allowing density calibration to proceed without stopping the main operation.
2Productivity
If calibration is performed by reading test images on a sheet after transfer, then the image forming operation can continue without interruption, but image density control accuracy decreases
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into multiple components: test images are formed on the image carrier (first test image) and on the sheet (second test image), with separate measurement processes for each. This allows the system to gather density information from both the carrier and sheet without interrupting operation.
Solution Approach 2:
The patent uses the image carrier as an intermediary medium for density measurement. The controller forms test images on the image carrier which serves as an intermediate transfer member, allowing density measurement before the final transfer to the sheet. This intermediary approach enables accurate measurement while maintaining continuous operation.
3Productivity
If test images are formed in marginal regions of the sheet, then calibration can be performed without interrupting image forming operations, but the available area for user images is reduced
Solution Approach 1:
The patent applies dimensionality change by moving the test image formation from the sheet surface (2D plane) to the image carrier (intermediate transfer member). The controller forms test images on the image carrier which rotates through the transfer process, allowing calibration without consuming sheet area. This dimensional shift enables continuous operation while preserving full sheet area for user images.
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
Enables high-accuracy control of image density without interrupting the image forming process, stabilizing output and maintaining productivity by using a combination of inline sensors and gradation correction patterns to adjust exposure intensity and generate a γ lookup table.
Implementation Method 1
a sensor configured to measure a measuring image on the image carrier
Implementation Method 2
a reader configured to read a pattern image on the sheet while conveying the sheet
Implementation Method 3
An image forming apparatus includes an image carrier, an image forming unit configured to form an image on the image carrier
Data Source
AI summary
An image forming apparatus includes an image forming unit configured to form an image on an image carrier, a transfer unit configured to transfer the image from the image carrier to a sheet, a reader configured to read a pattern image on the sheet while conveying the sheet, a sensor configured to measure a measuring image on the image carrier, and a controller configured to control the image forming unit to form the pattern image and the measuring image while forming images on a plurality of sheets, control the reader to read the pattern image, control the sensor to measure the measuring image, and generate an image forming condition based on a result of reading the pattern image by the reader and a result of measuring the measuring image by the sensor.