Top-Emission Exposure Head Layout for Efficient Photoconductor Imaging
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Solution Overview
Problem
Existing bottom emission light emitting devices in electrophotographic image forming apparatuses face challenges in achieving high light emission efficiency due to optical path limitations by the TFT circuit, necessitating increased light production.
Innovation Solution
An image forming apparatus with a top emission light emitting device utilizing a silicon substrate, a first electrode layer with a two-dimensional array of electrodes, a light emitting layer, and a common second electrode layer for transmitting light, coupled with a lens array to guide light onto a photoconductor, controlled by a drive circuit for image data alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a bottom emission light emitting device is used, then the device structure is simplified, but the light emission efficiency is reduced due to optical path limitations by the TFT circuit
Solution Approach 1:
The patent inverts the conventional bottom emission structure by adopting a top emission structure where light exits from the top side of the light emitting layer toward the photoconductor. This inversion eliminates the optical path limitations imposed by the TFT circuit on the bottom emission side, allowing light to be emitted directly onto the photoconductor surface without passing through the TFT circuit layer, thereby significantly improving light emission efficiency.
2Manufacturing precision
If the number of light emitting portions is increased to improve resolution, then the image quality improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the light emitting function with the drive circuit function by integrating the light emitting portions directly onto the drive circuit substrate. This integration eliminates the need for separate light emitting component assemblies and reduces the overall number of discrete components, while still enabling high-resolution image formation through precise control of the integrated light emitting portions.
Solution Approach 2:
The drive circuit substrate serves multiple functions: it provides the drive circuits for controlling the light emitting portions, supports the light emitting portions themselves, and acts as the mounting substrate for the entire exposure head assembly. This multi-functionality reduces the number of separate components needed and simplifies the overall device structure while maintaining high resolution capabilities.
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
Enhances light emission efficiency by optimizing electrode arrangement and transmission, allowing for high-density light emission and precise image formation without optical path restrictions, thus improving image quality and reducing component count.
Implementation Method 1
a light emitting layer formed in a layer on the first electrode layer and configured to produce light when a voltage is applied
Implementation Method 2
a lens array configured to guide light emitted from the light emitting device to a photoconductor surface
Data Source
AI summary
A second electrode is laminated on a light emitting layer on an opposite side across the light emitting layer from a first electrode laminated on a silicon substrate. The second electrode is capable of transmitting light. A photoconductor drum is exposed to light by using light transmitted through the second electrode.