Laser Driver IC Shading Correction for Image Forming Apparatus
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Solution Overview
Problem
High-speed and high-resolution image forming apparatuses face challenges in efficiently correcting non-uniform image densities due to varying light emission characteristics of multiple laser sources, leading to increased data communication requirements and prolonged data transmission times.
Innovation Solution
The implementation of a simplified light amount correction system for image forming apparatuses, where correction data is pre-calculated and stored in nonvolatile memory for each laser source, allowing for efficient light amount modulation and reduced data transfer, using a CPU and laser driver IC to control the light emission based on pre-defined profiles for each scan position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple laser beams are used to achieve high-speed and high-resolution image formation, then image forming speed and resolution are improved, but the number of data communication buses increases and data transmission time is prolonged
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing light amount setting data for each laser source in the storage medium of the beam scanning device before image formation. This allows the controller to only transmit correction data (shading data) rather than complete light amount setting data for all lasers, significantly reducing data transmission time while maintaining high-speed image formation capability
Solution Approach 2:
The patent segments the light amount control data into two parts: (1) light amount setting data specific to each laser source that is stored locally in the beam scanning device, and (2) correction data (shading data) that is transmitted from the controller. This segmentation reduces the amount of data that needs to be transmitted over the communication bus, resolving the contradiction between using multiple lasers and data transmission time
2Productivity
If multiple laser beams are used to achieve high-speed and high-resolution image formation, then image forming speed and resolution are improved, but the number of data communication buses increases
Solution Approach 1:
The patent merges the storage function for light amount setting data into the beam scanning device itself, combining the laser control functions and storage medium into a single integrated unit. This eliminates the need for separate communication channels for each laser's full parameter set, reducing the number of required data communication buses while supporting multiple laser beams for high-speed image formation
3Device complexity
If light amount setting data is transmitted serially to correct image density non-uniformity, then data transmission is simplified, but the data communication takes a lot of time
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing light amount setting data for each laser source in the storage medium of the beam scanning device before image formation. This allows the controller to only transmit correction data (shading data) rather than complete light amount setting data for all lasers, significantly reducing data transmission time while maintaining high-speed image formation capability
Solution Approach 2:
The patent segments the light amount control data into two parts: (1) light amount setting data specific to each laser source that is stored locally in the beam scanning device, and (2) correction data (shading data) that is transmitted from the controller. This segmentation reduces the amount of data that needs to be transmitted over the communication bus, resolving the contradiction between using multiple lasers and data transmission time
Data Source
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AI summary
An image forming apparatus capable of correcting light amounts of light beams which expose a photosensitive member with simple construction. The image forming apparatus includes a photosensitive drum, and a beam scanning device including a plurality of semiconductor lasers which emit light beams for exposing the photosensitive drum, and a memory which stores first correction data for correcting the light amount of each light beam in a manner associated with each of the plurality of semiconductor lasers. A CPU outputs second correction data for being commonly used in correcting the light amounts of the light beams emitted from the plurality of semiconductor lasers to the beam scanning device. A laser driver IC provided in the beam scanning device controls the light amount of the light beam emitted from each semiconductor laser based on the first correction data and the second correction data.