Dual-Row Exposure Head Rear-Surface Light Extraction
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Solution Overview
Problem
The existing exposure heads in electrophotographic systems, particularly those using organic EL elements, suffer from low light output due to light obstruction by TFT circuit wiring, which is inefficient and insufficient for high-speed applications like print on demand.
Innovation Solution
The exposure head design includes two rows of light emitting boards with alternating orientations and separate lens arrays to efficiently condense light onto the photosensitive drum, increasing light output by allowing multiple exposure and optimizing light distribution without obstructing the light path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light is extracted through the glass substrate in existing exposure heads, then the structure is simplified and manufacturing is easier, but the light is obstructed by TFT circuit wiring resulting in low light output
Solution Approach 1:
The patent inverts the conventional light extraction approach by extracting light from the rear surface of the glass substrate rather than the front surface. This allows light to escape through the transparent glass without being blocked by TFT circuit wiring, achieving both high light output and manufacturing simplicity
Solution Approach 2:
The patent extracts the harmful element (TFT circuit wiring obstruction) from the light path by changing the extraction direction. Light is taken out from the rear surface where no wiring obstructions exist, eliminating the blocking effect while maintaining the glass substrate structure
2Device complexity
If a single row of light emitting elements is used, then the device complexity is reduced, but the light amount reaching the photosensitive drum is insufficient for high-speed applications
Solution Approach 1:
The patent segments the light emitting structure into multiple rows (first and second light emitting element groups) disposed at different positions. Each row contributes to the total light output, enabling high-speed applications while maintaining manageable device complexity through modular arrangement
Solution Approach 2:
The patent adds a new dimension to the light emitting structure by disposing light emitting elements in multiple rows along the traveling direction of the photosensitive drum. This dimensional expansion increases light output without proportionally increasing device complexity
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 configuration enhances light utilization efficiency, ensuring sufficient light reaches the photosensitive drum, thereby achieving higher output and supporting high-speed printing applications without compromising image quality.
Implementation Method 1
a rod lens array condensing the light of the row of the light emitting elements onto the photosensitive drum
Implementation Method 2
the organic EL light emitting layer is formed, so that light from the organic EL light emitting layer is extracted through the transparent glass substrate
Data Source
AI summary
An exposure head includes a first light emitting board group, a first lens array, a second light emitting board group, and a second lens array. The first light emitting board group is disposing a plurality of first light emitting boards each including a plurality of first light emitting elements disposed side by side in a second direction intersecting with the first direction. The plurality of first light emitting boards are disposed along the second direction and alternately in the first direction. The first lens array condenses light emitted from the plurality of first light emitting elements disposed on the first light emitting board group onto the surface of the image bearing member. The second light emitting board group is disposed in a manner separated with respect to the first light emitting board group in the first direction.