How would you add a hand sensor to this glass?
Hello all. I make several custom touch screens out of 1/8" glass that is back painted using a silk screen. There is a PCB on the back that has reverse mounted LED that send light through the graphics( white area). I am re designing the process and getting a UV flatbed printer to print the graphics on the back instead of silkscreen which is such a pain to do for a number of reasons. On the re design I want to add a hand wave sensor that detects a hand within 4-5". I use a Avago(Broadcom APDS-9960 gesture sensor on some LCD type user interfaces and it works great but those methods allow for the sensor to mount in a recesses area in the plastic bezel around the LCD. On the glass, I am trying to avoid having to make a jig on the CNC to create the hole(oval shape) which involves having to cut with water. I've done it a lot but dont want to do that process anymore. The goal is to make a new PCB for that includes the touch sensor copper plane areas, but include some method of hand sensor on the board or attachable to the board. The APDS-9960 specifies max glass thickness of 1mm. I haven't tested the 1/8" glass but assume it wont work well, usually IR reflections from the top surface of the glass bounce back.
Using something like a Qprox QT1081 touch sensor IC( or similar newer variants), you have to be careful putting signals near the copper plane connected to sensor ICs so I am assuming IR is the best method. I can print the solid black ink and leave a small circle open for an IR sensor on the back to look through assuming something will work in 1/8" clear glass. Radar, Ping, laser TOF, RF all seem problematic. I will have a Prop1 on the PCB on the glass with lots of free pins. Ideally, an off the shelf small diameter IR sensor would be great. Small as in 3/8" diameter clear circle on the glass(no ink), mount the sensor behind the glass.
Any suggestions appreciated.