Transcript
Introduction to Bolt LED Testing
So today, we’re testing the LED indicator output of the Bolt. You can use wireless communication to talk to the Bolt with your phone, with a tablet, with a laptop through Bluetooth or Wi-Fi. But sometimes you’re in the field and the LEDs are your only indication of what is happening inside the Bolt, so we designed this intentionally to be easy to read and indicate a lot of information to the user, but also to be weatherproof.
We designed a custom translucent end cap that is ULV-0 rated for flammability purposes, but also avoids any extra penetrations in the housing to make sure the LEDs stay contained, that there’s no water ingress. So this is both a diffuser and part of the mechanical design of the Bolt.
Color Accuracy and Test Setup
As described in the Bolt Quick Start Guide, there are several different colors that you may encounter when using the Bolt, and we wanna make sure that the color accuracy on the LEDs is good, to make sure that they’re easily visible, make sure that we’ve avoided colors that are difficult for color-blind folks to see or distinguish.
So we’re going to be testing various metrics from these LEDs with the LED test apparatus that we have. We have an LED sensor. This can measure raw RGB and intensity values. Also, it can measure hues, saturation and intensity to determine color accuracy, and chromaticity to measure our ability to generate white with an RGBLED.
So this device has three fiber optic sensors that go over to this apparatus we have that has an output from each fiber optic sensor that mates up against the Bolt itself so that they’re aligned correctly with the three LEDs. So let’s arrange this and we’ll begin our test, which will go through a series of LED output states and gather data from the LED meter. And then we’ll analyze this to make sure that the LED RGB output is correct, the intensity is good, the hue is good for different colors, and that the chromaticity is within spec.
Running the Automated Test
So we’ll begin the test. This is an automated test. And first, we will gather data for each of the RGB states, so red, and we’re gathering the RGB data to make sure that the intensity is good. Here’s the green.
And to do this, we have a Python script that’s running that controls the LED states on the Bolt. We’re connected through Wi-Fi on the Bolt and this Python script is also querying the data from the LED meter. Now, here’s blue.
And then this is red at one-quarter intensity to make sure we have good control over the brightness or intensity of the LEDs. Now we’re going through the different colors that you might encounter that indicate different states. These are, again, on the Quick Start Guide.
So we have purple, we have orange, and these are all well-separated on the color wheel and we wanna make sure that the color rendering accuracy is good on the LEDs, that we’re generating the colors that we think we are. And then yellow. And to do this, we’ll gather the hue and saturation information to make sure that they are on the right spot on the color wheel.
And aqua. And finally, white. And for white, the metric is chromaticity. This is the accuracy of our ability to generate white with RGBLEDs. And now the test is complete. The script has put all the color information into the data file and we’ll analyze this with MATLAB to see how accurate our LED output is.
LED Separation Test
And for our final test, we’re gonna test the separation of the three LEDs. The diffuser is meant to make sure that a single RGBLED looks like one light source, but we don’t want it to over-diffuse. We don’t want one LED to bleed into the other. So we’re gonna run a test that put separate colors on the three LEDs, with alternating RGB and measure the output and make sure that there’s no bleed-over from one LED to the other.
Analyzing Results in MATLAB
So we gathered the data. Let’s analyze this in MATLAB and see how the Bolt LEDs do. We have a MATLAB script that includes the raw data and all the analysis and let’s run the script and look at the output.
Color Wheel Results
So here we have several graphs. We’re gonna start with the color wheel. We can see the different colors that we generated plotted on the wheel. We have yellow, orange, red, purple, blue, aqua, and green. These are the colors that we used to indicate various states on the Bolt, and they’re well-separated on the color wheel. They’re maximally separated, actually, very good saturation.
So we’re looking at the hue and saturation here, and the saturation is very high on all of ’em. These are very pure colors. So these should be very easy to distinguish for someone out in the field looking at these colors.
Brightness Control
Next we’re looking at the brightness control on the Bolt. We have half-brightness and full-brightness, and we’re looking at the intensity values, and we see the ratio’s 2.05, so that’s very good control over the brightness of the LEDs. We can make them as bright or as dim as we like.
LED Separation Results
The next figure is the LED separation. This is a measure of how well the LEDs are distinguishable. We want the diffuser to blend the RGB components of a single LED into one light source, but we don’t want the diffuser to over-diffuse and have one LED bleed into the other.
So this is a graph that’s showing that separation. We see a very large separation between the primary LED output and the amount of pickup of that color on the other LED points. This is a 10:1 separation, and keep in mind, this is a logarithmic plot, so the separation is actually much higher than that. So we have a good diffuser that is diffusing single LEDs, but not bleeding multiple LEDs together.
Chromaticity Results
And finally, we will look at the chromaticity of the Bolt LED output. This is a measure of the whiteness. When we set it to white here in the center, we see the Bolt LED, the three LEDs are very close together, near the one-third, one-third point. This D65 point is a standard, a 65 kelvin, 6,500 kelvin, reference symmetry that’s considered a good white, and this oval is considered a good white color. So we’re well within that circle.
The other thing this shows us is the gamut of the LED output. The corners of this larger triangle are the red, green, and blue outputs from the Bolt, and the interior of this larger triangle represents all the colors the Bolt can generate. It’s any combination of those. The smaller triangle is the standard RGB output that is used for measuring the capability of monitors and other types of displays. And we have 97.7% coverage, so that’s almost the entire gamut. That’s considered extremely good for a display system.
Conclusion
So we see that the Bolt LED system is well-designed. It can produce good colors. It can produce colors that are easily distinguishable by the user, good intensity, good brightness, and we have good control. So the Bolt LED system has passed all the tests to make sure that it is providing good indications for the user.
