Optoelectronic element with a non-protruding lens
View Patent ↗An optoelectronic component has a lens that is formed in the surface of an encapsulant surrounding a semiconductor diode element. With respect to emitters, the lens reduces internal reflection and reduces dispersion to increase overall efficiency. With respect to detectors, the lens focuses photons on the active area of the detector, increasing detector sensitivity, which allows a detector having a reduced size and reduced cost for a given application. The lens portion of the encapsulant is generally nonprotruding from the surrounding portions of the encapsulant reducing contact surface pressure caused by the optoelectronic component. This non-protruding lens is particularly useful in pulse oximetry sensor applications. The lens is advantageously formed with a contoured-tip ejector pin incorporated into the encapsulant transfer mold, and the lens shape facilitates mold release.
1. A non-reflectance pulse oximetry sensor capable of being positioned in proximity to a person's skin, the pulse oximetry sensor comprising:
an encapsulant having a surface positionable in proximity to the skin;
a lens comprising a curved lens portion of the surface of the encapsulant;
a generally smooth portion of the surface of the encapsulant, wherein the lens does not protrude substantially beyond the generally smooth portion, thereby avoiding forming a pressure necrosis at the skin;
a trough between the curved lens portion and the generally smooth portion of the surface of the encapsulant, the trough having a sidewall spaced from the lens; and
an optoelectronic element embedded in the encapsulant, the optoelectronic element emitting light through at least a portion of the lens to the skin.
2. The non-reflectance pulse oximetry sensor of claim 1 , wherein the non-reflectance pulse oximetry sensor is a transmission pulse oximetry sensor.
3. The non-reflectance pulse oximetry sensor of claim 1 , wherein the optoelectronic element comprises a first light emitting diode operable to transmit light through at least a portion of the lens.
4. The non-reflectance pulse oximetry sensor of claim 3 , further comprising a second light emitting diode embedded in the encapsulant and operable to transmit light through at least a portion of the lens.
5. The non-reflectance pulse oximetry sensor of claim 4 , wherein the first light emitting diode transmits wavelengths in the red portion of the electromagnetic spectrum and the second light emitting diode transmits wavelengths in the infrared portion of the electromagnetic spectrum.
6. The non-reflectance pulse oximetry sensor of claim 1 , wherein the lens further comprises a flat lens portion which lies substantially parallel to the generally smooth portion of the surface of the encapsulant.
7. The non-reflectance pulse oximetry sensor of claim 1 , wherein the lens has a generally circular cross-section in at least one plane.
8. The non-reflectance pulse oximetry sensor of claim 1 , wherein the lens has a generally parabolic cross-section in at least one plane.
9. The non-reflectance pulse oximetry sensor of claim 1 , wherein the curved lens portion is spherically-curved.
10. The non-reflectance pulse oximetry sensor of claim 1 , wherein the curved lens portion is parabolically-curved.