Organic EL Print Head Light Emission Control
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Solution Overview
Problem
The existing LED print heads in electrophotographic apparatuses have limited position accuracy due to their complex configuration, while organic EL print heads, made with organic EL luminescence material on a low temperature polycrystalline silicon thin film transistor, offer high precision but face challenges in maintaining light intensity and longevity during image formation.
Innovation Solution
The organic EL print head is designed with a staggered light emitting element array configuration and a control system that adjusts light emitting timing and intensity to prioritize either image quality or print head longevity, using a DRV circuit and D/A conversion circuit to manage light emission and non-emission, thereby forming high-density images with controlled density and reduced light attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LED print head is used, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent replaces the mechanical chip arrangement system with an organic EL material deposition system. Instead of manually or mechanically positioning LED chips, the invention uses vapor phase deposition to form organic EL luminescence materials directly at precise locations on the substrate, eliminating mechanical positioning errors and achieving high manufacturing precision through a chemical deposition process.
2Manufacturing precision
If organic EL print head is used, then manufacturing precision is improved, but light intensity deteriorates
Solution Approach 1:
The patent changes the material parameters by developing organic EL luminescence materials with enhanced light emission characteristics. Through material composition optimization and deposition parameter control, the invention achieves both high positioning precision and sufficient light intensity, resolving the contradiction between precision and illumination performance.
3Manufacturing precision
If organic EL print head is used, then manufacturing precision is improved, but duration of action deteriorates
Solution Approach 1:
The patent optimizes operational parameters including driving voltage, current density, and pulse width modulation to extend the service life of organic EL elements. By controlling the electrical parameters and emission duty cycle, the invention maintains high positioning precision while significantly improving the duration of action and reliability of the print head.
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 image quality by minimizing density variations and extends the print head's lifespan by optimizing light usage, ensuring consistent halftone image density and prolonged operational life.
Implementation Method 1
an exposure device including organic EL (Electroluminescence) as a luminescence material
Data Source
AI summary
In accordance with an embodiment, an image forming apparatus comprises a light emitting element array comprising a low temperature polysilicon transistor and a plurality of light emitting elements that emit light at luminance corresponding to an output current of the transistor; and a processor configured to select either one of a first mode in which the light emitting element emits light for a first irradiation time at a first light quantity per unit area and a second mode in which the light emitting element emits light for a second irradiation time longer than the first irradiation time at a second light quantity less than the first light quantity per unit area, and control emission of light from the plurality of light emitting elements to expose a photoconductor according to acquired image data and a selected mode.