Optical Low-Pass Filter With Transparent Conductive Coating
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Solution Overview
Problem
Existing optical low-pass filters and infrared blocking filters are prone to dirt and dust attachment due to static buildup, leading to image quality issues, and current solutions that address this problem increase the number of components and reduce productivity.
Innovation Solution
An optical low-pass filter with a coating layer comprising alternately disposed high-refractive and low-refractive layers, where at least one high-refractive layer is made of transparent conductive material, effectively preventing dirt and dust attachment while allowing for infrared blocking and reducing light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transparent conductive film is formed on the surface of the optical device to remove static electricity, then dirt and dust attachment is prevented, but light reflection increases due to the high refraction index of the metal coating
Solution Approach 1:
The patent uses a composite coating structure combining transparent conductive material (ITO) with dielectric layers (SiO2, MgF2). This composite approach allows the conductive layer to provide anti-static functionality while the dielectric layers with appropriate refraction indices reduce light reflection through constructive interference and destructive interference effects, resolving the contradiction between conductivity and light transmission.
Solution Approach 2:
The patent applies different materials with specific properties to different layers of the coating structure. The transparent conductive material provides local conductivity for dirt prevention, while the dielectric layers provide local optical properties for reflection control. Each layer is optimized for its specific function, allowing both requirements to be satisfied simultaneously.
2Reliability
If separate optical low-pass filter and infrared blocking filter are provided, then functional requirements are met, but device size increases and productivity decreases
Solution Approach 1:
The patent merges the low-pass filter and infrared blocking filter into a single integrated optical device. The coating layer structure simultaneously achieves both functions by using materials and layer configurations that block infrared radiation while also filtering out specific spatial frequencies, thereby reducing component count and simplifying the imaging apparatus.
Solution Approach 2:
The single optical device performs multiple functions: it acts as both a low-pass filter for spatial frequency control and an infrared blocking filter for radiation management. This multi-functional design eliminates the need for separate components, reducing device complexity while maintaining all required functional performances.
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 preventing dirt and dust attachment, reduces the number of components, and increases manufacturing productivity, allowing for size reduction of imaging devices without compromising light transmission or conductivity.
Implementation Method 1
at least one of the high-refractive layers is made of a transparent conductive material so that the attachment of dirt and dust to the surface of the coating layer is prevented
Implementation Method 2
a coating layer formed to the base material on the light-entering surface side. The coating layer includes a high-refractive layer and a low-refractive layer sequentially disposed alternately on one on the other for reflecting or passing through a light of a specific wavelength range
Implementation Method 3
the coating layer may be the one that blocks infrared radiation
Data Source
AI summary
On the light-entering surface side of a base material 10, a coating layer 11 in which a high-refractive layer and a low-refractive layer are sequentially disposed alternately on one on the other is provided for blocking infrared radiation. One of the high-refractive layers is configured by an ITO film 11a so that the conductivity is increased on the surface of the coating layer. Herein, in view of preventing, to a further extent, the attachment of dirt and dust by providing the conductivity to the surface of the coating layer, it is desirable if the outermost high-refractive layer is made of a transparent conductive material. Moreover, it is desirable if the total layer thickness is 140 nm or smaller for the refractive layers formed outside of the high-refractive layer made of the transparent conductive material.