Mesa Light Emitter Sidewall Shielding for Encoder Noise Reduction
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Solution Overview
Problem
Light leaking out of the side surface of a light emitting element in a reflective-type encoder can be detected as noise, leading to a decline in detection accuracy.
Innovation Solution
A light emitting element with a metal layer extending along the side surface of the mesa portion, overlapping the active layer, and a resin layer with a thickness decreasing toward the substrate, which effectively blocks leakage light and facilitates the formation of the metal layer on the side surface, preventing noise detection in reflective-type encoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal layer is formed on the side surface of the mesa portion to block leakage light, then detection accuracy is improved, but it becomes difficult to satisfactorily form the metal layer on the side surface
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the mesa portion side surface and the metal layer. This resin layer serves as a mediator that enables the metal layer to be satisfactorily formed on the side surface by providing a suitable interface, thus resolving the manufacturing difficulty while maintaining the light-blocking function that improves detection accuracy.
Solution Approach 2:
The patent changes the physical parameters of the side surface environment by introducing the resin layer, which modifies the surface properties and geometric constraints. This parameter change enables the metal layer formation process to proceed satisfactorily, allowing the light-blocking function to be achieved without manufacturing difficulties.
2Object-generated harmful factors
If the metal layer extends along the side surface to block leakage light, then leakage light is suppressed, but the device structure becomes more complex
Solution Approach 1:
The patent segments the light-blocking function into two distinct parts: the first part (metal layer on top surface) and the second part (metal layer on side surface). This segmentation allows each part to be optimized for its specific function - the first part for electrical connection and the second part for blocking leakage light - thereby suppressing leakage light while managing device complexity through functional division.
Solution Approach 2:
The patent extends the light-blocking function from the top surface into the vertical dimension by forming the second part of the metal layer along the side surface. This dimensional extension effectively blocks leakage light that escapes from the sides, addressing the harmful effect while organizing the structure in multiple dimensions to manage complexity.
3Area of stationary object
If the light passage opening is formed closer to one side of the mesa portion, then the region for external connection is widened, but light is more likely to leak out of the side surface
Solution Approach 1:
The patent segments the light passage opening position from the light-blocking function by introducing the side surface metal layer (second part). This allows the light passage opening to be positioned optimally for external connection on the top surface, while the separate second part on the side surface independently handles the leakage light blocking, thus resolving the contradiction between connection region size and light leakage prevention.
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 solution effectively suppresses leakage light from the side surface of the light emitting element, enhancing detection accuracy in reflective-type encoders by ensuring the metal layer is satisfactorily formed on the side surface, even in complex geometries, and efficiently attenuating light leakage.
Implementation Method 1
the second part overlaps at least the active layer when viewed in a direction perpendicular to a thickness direction of the substrate. As a result, light leaking out of the side surface of the mesa portion can be blocked by the second part
Implementation Method 2
the resin layer with a thickness decreasing toward the substrate, which effectively blocks leakage light and facilitates the formation of the metal layer on the side surface, preventing noise detection
Data Source
AI summary
A light emitting element includes: a substrate; a mesa portion formed on the substrate and including an active layer, a first semiconductor layer, and a second semiconductor layer; a metal layer including a first metal part disposed on a top surface of the mesa portion and connected to the second semiconductor layer and a second metal part formed integrally with the first metal part and extending along a side surface of the mesa portion; an insulating layer formed on the side surface; and a resin layer formed on the insulating layer. The first metal part includes an opening region formed with a light passage opening and a connection region for external connection. The second metal part is formed on the side surface via the insulating layer and the resin layer and overlaps the active layer when viewed in a direction perpendicular to a thickness direction of the substrate.