Optical Sensing Module Inversion for Assembly Precision
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Solution Overview
Problem
The accuracy of light focusing in optical mice is compromised due to assembly errors caused by deformation of the compound, height errors in the optical sensing die, and thickness errors in the printed circuit board, leading to inefficient focusing of light on the optical sensing die.
Innovation Solution
The optical sensing module positions the packaging body on the lower surface of the printed circuit board and fixes it using the shoulder portion of the lead frame, preventing assembly errors from compound deformation and printed circuit board thickness, thereby improving assembly precision and light focusing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the packaging body is positioned on the upper surface of the printed circuit board with the lead frame bent and inserted through the board, then the assembly process follows conventional methods, but assembly precision deteriorates due to compound deformation, optical sensing die height error, and printed circuit board thickness error
Solution Approach 1:
The packaging body is inverted and positioned on the lower surface of the printed circuit board instead of the upper surface. The lead frame extends downward and is fixed to the lower surface, reversing the conventional assembly direction. This inversion eliminates the accumulation of errors from compound deformation and board thickness variations, achieving higher assembly precision while maintaining ease of manufacture.
2Device complexity
If the lead frame is fixed to the upper surface of the printed circuit board, then the conventional assembly structure is maintained, but light focusing accuracy deteriorates due to interval D error between the optical sensing die and lens unit
Solution Approach 1:
The lead frame and packaging body are inverted to face the lower surface of the printed circuit board. This inversion repositions the optical sensing die at a precise height relative to the lens unit, eliminating interval D errors that affect light focusing accuracy. The assembly structure remains simple while achieving superior optical alignment.
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 solution enhances the precision of the optical sensing module assembly, ensuring accurate light focusing on the optical sensing die, thereby improving the overall performance of the optical mouse.
Implementation Method 1
the light 110 reflected from the object, which, for example, is a mouse pad
Implementation Method 2
The compound has a transparent surface 142... the optical sensing die 146 is packaged in the compound 140
Implementation Method 3
the light 110 reflected from the object... may be focused on the optical sensing die 146
Data Source
AI summary
In an optical mouse, an optical sensing module includes a printed circuit board and a packaging body. The printed circuit board has an upper surface and a lower surface on opposite sides. The packaging body including a compound, an optical sensing die and a lead frame is disposed on the lower surface. The compound has a transparent surface. The optical sensing die used for receiving light is located inner the compound and has an optical sensing surface facing the transparent surface of the compound. The lead frame with a shoulder portion is electrically connected to the optical sensing die. The shoulder portion extends out from the compound along a direction that is parallel to the optical sensing surface of the optical sensing die. The shoulder portion is fixed on the lower surface. The optical sensing module may be used in an optical mouse. In the above optical sensing module, since the packaging body is positioned on the lower surface of the printed circuit board and the shoulder portion is fixed thereon, a preciseness of assembling the above optical sensing module can be easily improved.