Today’s Tech: Automating a Motorized Projector Screen
Part of the responsibilities as an engineer at Functional Devices is to answer the technical support calls and emails that come in to the office. Calls can sometimes be routine – from confirming device specifications and device operation to giving a RIB® suggestion to the individual’s problem they may have.
Home media is one of my many off-and-on interests, so when I received a technical support call to suggest a RIB® solution to control a motorized video projection screen, my interest was quickly piqued! Our customer called to see if there was a way to incorporate a RIB® relay to raise or lower the screen based on the status of the digital projector.
Goal: When the projector is turned on, the screen lowers and when the projector is turned off, the screen rises.
Cool! Now, I know some projectors have a dedicated RJ-45 output to connect to some brands of motorized screens for the purpose of sending a signal to raise or lower the screen, but this was clearly not the case. Our customer noted that a limit switch would also be used to stop the screen as it lowers to prevent damage to the motor or screen material. Upon receiving the call, my mind immediately went in the direction of a RIB® current sensor and relay combination – but which relay and current sensor? There are so many options!
Why did I decide on these two devices?
Well, let’s start with the current sensor. Model RIBXGA is a split core current sensor with an adjustable threshold. I had the idea of sensing the current flow to the projector. Projector on = current flow. Projector off = little to no current flow. I suggested the adjustable option, as I was not sure if there would be any “stand-by” current to the projector (i.e. current flow to keep the infrared sensor in the projector ON to see the remote control). The adjustability allows for the current sensor to “look over” the stand-by current that may be there. This will ensure a true ON command from the current sensor.
Model RIB21CDC with a dry contact input relay was suggested because this relay has a pair of wires available to sense the closure of a dry contact output, which is exactly what the output is on the current sensor. When the current sensor detects current flow, the normally-open contact on the sensor will close. The RIB21CDC will sense the closure and then close its normally-open relay contact. Only because the RIBXGA current sensor cannot handle the load of a motor did I suggest the combination of the RIB21CDC and the RIBXGA.
The customer took my suggestion and gave it a shot. No one called back, so I can only assume that the suggestion worked! Always feel free to give us a call if our device is not working as expected or if you need a suggestion, and we will help to solve the problem – hopefully with a RIB® device!