Semiconductor Sensor Unit Rear-Side Contact Position Measuring Device
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Solution Overview
Problem
Existing position measuring devices with optical scanning are sensitive to contamination, particularly liquid droplets, which can reduce light evaluation and scatter light, leading to unreliable position measurements.
Innovation Solution
The position measuring device features a semiconductor sensor unit with photodetectors on its front side and electrical connections routed via metal through-contacts to the printed circuit board, eliminating wire bonding and potting compound, allowing for a reduced scanning distance of less than 0.55 mm and potentially down to 0.03 mm, thereby minimizing contamination and scattering effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding and potting compound are used to connect the sensor unit to the printed circuit board, then electrical connections are established, but the scanning distance increases and contamination sensitivity increases
Solution Approach 1:
The patent removes wire bonding and potting compound from the connection structure, extracting the harmful elements that increase scanning distance and contamination sensitivity. The sensor unit is connected directly to the printed circuit board via contact surfaces, eliminating the intermediate bonding structures.
Solution Approach 2:
Instead of connecting the front side of the sensor unit to the printed circuit board (which requires wire bonding and increases scanning distance), the patent inverts the approach by routing connections through the rear side of the sensor unit, allowing direct contact without intermediate structures.
2Reliability
If a scanning plate is used to protect the photodetectors, then mechanical protection is provided, but the scanning distance increases and light scattering increases
Solution Approach 1:
The patent removes the scanning plate from the optical path, extracting the element that causes light scattering and increases scanning distance. The photodetectors are exposed directly to the measuring graduation without an intermediate protective plate.
Solution Approach 2:
Instead of a rigid scanning plate, the patent uses a thin protective window that provides mechanical protection while minimizing light scattering and maintaining a small scanning distance. The protective window is optimized to be as thin as possible while still providing protection.
3Reliability
If the scanning distance is reduced to less than 0.55 mm, then contamination resistance improves, but the connection structure becomes more complex
Solution Approach 1:
The patent replaces the mechanical wire bonding system with a direct contact connection system. The sensor unit has contact surfaces on its rear side that directly contact corresponding contact surfaces on the printed circuit board, eliminating the need for wire bonding machinery and processes.
Solution Approach 2:
The patent merges the electrical connection function with the mechanical mounting function. The same contact surfaces that provide electrical connection also provide mechanical attachment, eliminating the need for separate wire bonding and mounting operations.
4Reliability
If wire bonding is used to connect the sensor unit, then electrical connections are established, but the scanning distance increases and the structure is more complex
Solution Approach 1:
The patent removes wire bonding from the connection structure, extracting the element that increases scanning distance. The sensor unit is connected directly to the printed circuit board via contact surfaces without intermediate bonding wires.
Solution Approach 2:
Instead of making electrical connections from the front side of the sensor unit (which increases scanning distance), the patent moves the connection interface to the rear side of the sensor unit, changing the spatial dimension of the connection and reducing the scanning distance.
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 design enhances the device's resistance to contamination, improves light detection reliability, and reduces the risk of mechanical and electrical failures by minimizing the scanning distance and eliminating the need for a scanning plate, resulting in more accurate and robust position measurements.
Implementation Method 1
at least two photodetectors are arranged on a front side of the sensor unit facing the measuring graduation and detect light emitted by an illumination unit and modulated by the measuring graduation
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The present invention relates to a position measuring device comprising a scale (40) and a scanning unit (10) which are arranged to be movable relative to each other in a measuring direction (X), wherein a measuring scale (41) is arranged on the scale (40) which can be scanned by the scanning unit (10) to generate position signals, and the scanning unit (10) for this purpose comprises a lighting unit (20) and a detector unit (30), wherein light can be emitted from the lighting unit (20) in the direction of the measuring scale (41) and light modulated by the measuring scale (41) can be detected by the detector unit (30), and wherein the detector unit (30) comprises a printed circuit board (31) and a sensor unit (32) which is designed as a semiconductor chip.The invention is characterized in that at least two photodetectors (35) are arranged on a front side of the sensor unit (32) facing the measuring scale (41), and the electrical connections of the sensor unit (32) are led to contact surfaces (33) on its rear side by means of metallic vias (36), and the sensor unit (32) is connected via the contact surfaces (33) to corresponding contact surfaces (34) on the circuit board (31). (Figure 1).