Pyroelectric Infrared Sensor Thinness via Filter and Cover
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Solution Overview
Problem
Existing pyroelectric infrared sensor devices face challenges in achieving thinness due to the use of lenses and dome-type housings, which hinder their miniaturization and integration into compact designs.
Innovation Solution
A pyroelectric infrared sensor device design that replaces lenses with an infrared transmission filter and a cover member, allowing for a thinner form factor while maintaining high infrared light transmittance and blocking visible light, using materials like high-density polyethylene, glass, or ABS resin for the cover member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lenses are used to condense infrared light on the pyroelectric element, then the infrared detection function is improved, but the device thickness increases
Solution Approach 1:
The patent removes the lens component from the optical system and replaces it with an infrared transmission filter that has light-condensing functionality integrated into its structure. This extraction of the lens while maintaining the light-condensing function through the filter resolves the contradiction between detection function and device thickness.
Solution Approach 2:
The patent combines the infrared transmission filter and the light-condensing function into a single component. The filter not only transmits infrared light but also condenses it onto the pyroelectric element, eliminating the need for a separate lens and reducing overall device thickness.
2Reliability
If a dome type housing is used to protect the sensor, then the sensor is protected from external factors, but the device thickness increases
Solution Approach 1:
The patent removes the dome-type housing and replaces it with a flat plate housing structure. This extraction eliminates the unnecessary curvature and thickness associated with dome housings while maintaining the protective function through the flat plate design combined with the infrared transmission filter.
3Reliability
If the cover member transmits infrared light effectively, then the infrared signal transmission is improved, but visible light may interfere with the sensor
Solution Approach 1:
The patent applies different optical properties to different parts of the cover member and optical system. The infrared transmission filter is designed to be highly transparent to infrared light while being opaque or absorbing to visible light, creating local quality differentiation that allows selective light transmission based on wavelength.
Solution Approach 2:
The patent utilizes the wavelength-selective transmission properties of the infrared transmission filter, which effectively changes its optical characteristics based on the wavelength of incident light. The filter appears opaque to visible light but transparent to infrared light, enabling discrimination between harmful visible light and useful infrared signals.
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
The design achieves significant thinning of the pyroelectric infrared sensor device, enabling its integration into various applications such as mobile devices and security systems without visible indicators, while maintaining sensitivity and wide-angle views.
Implementation Method 1
A pyroelectric element is an element for detecting the light including infrared light by a pyroelectric effect
Implementation Method 2
the infrared transmission filter has a property to transmit light equal to or greater than a wavelength of 1 μm
Implementation Method 3
the cover member has a property that a transmittance of infrared light having a wavelength of from 3 μm to 5.5 μm is equal to or greater than 10%
Data Source
AI summary
A pyroelectric infrared sensor device comprising: a pyroelectric infrared sensor part (2); and a cover member (3). The pyroelectric infrared sensor part comprises: a pyroelectric element (21); a housing (24) that the pyroelectric element is placed inside of and comprises an opening at a position facing a light receiving surface of the pyroelectric element; and an infrared transmission filter (25) that is located to cover the opening of the housing. The cover member covers at least a top surface of the pyroelectric infrared sensor part. The infrared transmission filter transmits light equal to or greater than a wavelength of 1 μm. The cover member has a property that a transmittance of infrared light having a wavelength of from 3 μm to 5.5 μm is equal to or greater than 10% and has a uniform material quality in an area corresponding to the top surface of the pyroelectric infrared sensor part.