Custom Back-up Camera
April 2021
Starting in 2018, the U.S. National Highway Traffic Safety Administration announced that it would require all automobiles sold in the United States to include backup cameras. Though not required until then, many cars included them much earlier. As a engineer, I have a constant want to improve things and find solutions and/or improvements to problems. When I bought my 2011 Infiniti G37, I noticed an issue when I was driving. Because of the structure of the car, the rear visibility can be bad. When driving, I noticed I couldn't see behind me very well. This can obviously be problematic, especially when changing lanes and backing up. Thankfully, the car comes with a back-up camera, which greatly helps reversing anywhere. Though true, turning and changing lanes can still be problematic. To improve this, I have decided to revise my back-up camera to come on when putting the turn signal on.
To have the camera come on with the turn signal, it's important to first find out how the camera comes on. From the factory, the camera comes on when the car is in reverse. The system for this is actually quite simple. When the car is in reverse, the reverse lights come on. The reverse lights are connected to the reverse camera, powering it up when they're on. Once the power is on, the display inside the vehicle recognizes a video signal. The display then changes from the current screen to the camera. When the car is not in reverse, the camera has no power, thus has no output, and the display doesn't recognize it.
With this knowledge, it's fairly simple to have the back-up camera turn on when the turn signals are on. Firstly, I determined I wanted the ability to switch between different camera modes. I wanted to have a reverse only mode, a reverse and turn signal mode, and a continuously on mode. To do this, I implemented a 3-position switch connected to the camera. Connected to the switch is the turn signal, the reverse light, and a 12V voltage source, which will be my car battery. Unfortunately, this system alone will have a few issues. Firstly, the voltage sources could cause each other to turn on or have reverse current. For example, the reverse light could cause the turn signal to turn on. To prevent this, each voltage source needs a diode in series. Additionally, the power from the turn signal is pulsating. This will cause the back-up camera output to pulsate and potentially not work at all. To solve this issue, an LC filter is used. The LC filter takes the pulsating voltage source and smooths it out to a fairly linear output voltage, which is seen in the diagram to the right.
