Recessed Lens Block for Infrared Sensor Accuracy
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Solution Overview
Problem
Conventional infrared sensors with silicon lens holders suffer from measurement errors due to infrared radiation entering from the holder, leading to complex and inaccurate lens formation processes.
Innovation Solution
An optical device design featuring a lens block with a recessed portion formed by the lens and a sealing member, where the sealing member covers the lens to prevent unwanted infrared radiation from entering, and a frame material with low emissivity to reflect infrared radiation, ensuring accurate and efficient measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lens holder is formed of silicon to enable easy manufacturing, then the manufacturing process is simplified, but infrared radiation transmitted through the lens holder causes measurement errors
Solution Approach 1:
The harmful function of the lens holder (transmitting infrared radiation) is extracted and eliminated by introducing a reflective layer. The lens holder retains its silicon material for easy manufacturing, but the reflective layer prevents infrared radiation from reaching the sensor, thus removing the harmful effect while preserving the beneficial manufacturing simplicity.
Solution Approach 2:
The harmful infrared radiation transmitted through the silicon lens holder is converted into a beneficial reflection. By applying a reflective layer (such as aluminum or silver) to the inner surface of the lens holder, the transmitted infrared radiation is reflected away from the sensor, transforming the harmful transmission into a useful reflection that improves measurement accuracy.
2Measurement precision
If the inner wall of the lens holder is protected by metal to prevent infrared transmission, then measurement accuracy is improved, but the lens forming process becomes complicated
Solution Approach 1:
The lens holder is designed to serve multiple functions: it provides structural support, maintains the lens position, and through the addition of a reflective layer, also prevents infrared radiation transmission. This multi-functional design eliminates the need for separate protective structures, simplifying the overall device complexity while maintaining measurement accuracy.
Solution Approach 2:
The lens holder structure combines silicon (for easy manufacturing and structural integrity) with a reflective coating layer (for infrared radiation prevention). This composite structure leverages the advantages of both materials: the silicon provides mechanical stability and ease of fabrication, while the reflective layer blocks infrared radiation, achieving both manufacturing simplicity and measurement accuracy.
3Volume of moving object
If the optical device is made compact by reducing the lens holder size, then the device profile is thinned, but infrared radiation from surrounding areas may enter the sensor
Solution Approach 1:
The reflective layer acts as an intermediary between the external environment and the sensor. It intercepts infrared radiation from surrounding areas before it can reach the sensor, even when the device is compact. This intermediary layer ensures that the reduced device size does not compromise the sensor's protection from infrared interference.
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 enhances measurement accuracy and simplifies the lens formation process while suppressing temperature changes in the lens block, resulting in a compact and highly accurate optical device.
Implementation Method 1
the infrared radiation is collected onto infrared detecting elements through a lens
Implementation Method 2
infrared detecting elements through a lens, thereby enabling detection of the temperature
Implementation Method 3
the inner wall of the lens holder is protected by metal or the like that does not transmit infrared light
Implementation Method 4
a frame material with low emissivity to reflect infrared radiation
Data Source
AI summary
The optical device includes a photoelectric conversion block including a photoelectric conversion chip configured to include photoelectric conversion elements arranged in a matrix and a first sealing member configured to cover side faces of the photoelectric conversion chip to expose the photoelectric conversion chip and a lens block including a lens and a second sealing member configured to cover side faces of the lens to expose one surface and an other surface of the lens. In the lens block, the one surface of the lens and the second sealing member forms a recessed portion, at least a part of a bottom surface of the recessed portion being formed by the one surface of the lens, a sidewall of the recessed portion being formed by the second sealing member, and the recessed portion being arranged such that the photoelectric conversion chip exposed from the first sealing member is covered.