Combined laser transmitter and photodetector receiver package
View Patent ↗Reflective optical sensors. A reflective optical sensor for sensing the presence of an object can include a reflective sensor package having a first cavity and a second cavity. The first and second cavities can be located side-by-side in the sensor package. A vertical cavity surface emitting laser (VCSEL) can be located within the first cavity for producing an optical emission. An optical receiver can be located within the second cavity and configured to receive at least a portion of the produced optical emission that is reflected from the object such that when the reflected emission is above a threshold strength the object is determined to be present. The optical receiver can be a shunt phototransistor and can include reverse bias protection.
1. A reflective optical sensor for sensing the presence of an object comprising:
a reflective sensor package made of a resilient plastic material comprising:
a first cavity including two opposing outwardly sloped sidewalls; and
a second cavity including two opposing outwardly sloped sidewalls, the second cavity located next to the first cavity in the sensor package such that a physical barrier is disposed between the first and second cavities, wherein the physical barrier becomes gradually thinner between the openings of the first and second cavities toward the openings of the first and second cavities due to the outwardly sloped sidewalls of the first and second cavities, wherein the first and second cavities are only partially filled with an at least partially transparent resin;
a VCSEL located within the first cavity for producing an optical emission;
a shunt phototransistor including reverse bias protection located within the second cavity configured to receive at least a portion of the produced optical emission reflected off of the object, the shunt phototransistor including reverse bias protection comprising:
an emitter;
a collector;
a base;
a diode including an anode and a cathode, the anode being electrically coupled with the base, and the cathode being electrically coupled with the collector;
a shunt internal resistor electrically coupled between the anode and the emitter creating a PN junction relationship, the PN junction relationship being disposed in parallel electrical relationship with the diode and the first resistor; and
a reverse bias protection internal resistor coupled in electrical communication between the first resistor and the emitter.
2. The reflective optical sensor of claim 1 , wherein the shunt phototransistor includes low light level rejection at a predetermined knee point.
3. The reflective optical sensor of claim 1 , wherein the shunt phototransistor has a predetermined light current slope.
4. The reflective optical sensor of claim 1 , further comprising: a first electrical contact electrically coupled to the VCSEL; a second electrical contact electrically coupled to the VCSEL; a third electrical contact electrically coupled to the shunt phototransistor; and a fourth electrical contact electrically coupled to the shunt phototransistor.
5. A reflective optical sensor according to claim 1 , further comprising: a first electrical contact electrically coupled to the VCSEL; a second electrical contact electrically coupled to the VCSEL; a third electrical contact electrically coupled to the shunt phototransistor; a fourth electrical contact electrically coupled to the shunt phototransistor; and the least partially transparent resin filling the first cavity and the second cavity allowing optical transmission to the shunt phototransistor and from the VCSEL.
6. The reflective optical sensor of claim 1 , wherein the optical emission is unfocused as it is transmitted from the VCSEL, reflected by the object, and received by the shunt phototransistor.
7. The reflective optical sensor of claim 1 , wherein the reflective optical sensor does not include a focusing lens.
8. The reflective optical sensor of claim 1 , wherein the VCSEL creates an emission having an angular emission window of about 20-30 degrees.
9. The reflective optical sensor of claim 1 , wherein the reflective optical sensor is at least as small as 3 millimeters or smaller.
10. The reflective optical sensor of claim 1 , further comprising an array of VCSELs for producing optical emissions.
11. The reflective optical sensor of claim 1 , wherein the first cavity surrounds the VCSEL on five sides of the VCSEL, and wherein the second cavity surrounds the shunt phototransistor on five sides of the shunt phototransistor.
12. The reflective optical sensor of claim 1 , wherein the emission from the VCSEL is produced at an angle to a top surface of the reflective optical sensor.
13. The reflective optical sensor of claim 12 , wherein the angle is determined based on a particular application of the reflective optical sensor.
14. The reflective optical sensor of claim 12 , wherein the angle is determined based on a distance between the reflective sensor and the object.