LED Refresh Rate

[abem]

Greetings,

Since I've had a watch using a Frontier 1602 module (used in the Hamilton QED II and Omega Constellation 1602 watches), I noticed that the display has a distinctive scintillation. I guessed that it was because the module had a lower refresh rate than others (30 Hz verses 60 Hz). The other night, I looked over at my camera sitting on the desk and thought I might check this out. So, I simultaneously waved my Omega Constellation and Hamilton QED I (using a Time Computer module) in front of the lens. Here is the result:

Omega / Frontier (left) and Hamilton / Time Computer (right):


A couple things are evident:
1) The refresh rate of the Frontier is half that of the Time Computer module
2) The duty cycle (length of time that the LED display is on) is much longer on the Frontier than on the Time Computer
3) The order that the digits are cycled through is reversed on the Frontier (right to left) as opposed to the Time Computer module (left to right)

So, anyhow, I know this is completely trivial, but I thought some might find it to be of interest. If anyone knows of any other "sparkly" modules, it would be interesting to hear about them.

-abe.

[rewolf]

Interesting observations, I second your conclusions from the photo.
Does the TC module have a light sensor? Would explain the low duty cycle when waving it in the dark.

[abem]

Rewolf,

Yes, the TC module does have a light sensor. The two display are not visually much different in brightness - the Frontier appears to be a bit brighter. In the photo, the TC digits appear a pinkish color rather than red which is what happens when red is overexposed and bleeds out into the other color channels.

So, it looks like the frontier is using long pulses of low brightness and the TC is using short pulses of high brightness, for whatever reason. This is also verified by the fact that on a few photos, I caught the Frontier digits in the process of fading out whereas the TC digits always appeared to be on or off.

-abe.

[LEDluvr]

Most Fascinating......



I wonder how the display of a modern LED watch would appear using the same experiment? Say, an Addidas or Majestic for example?

[abem]

LEDLuvr,

Love the spock image! I'm guessing that the modern LEDs have a lower refresh rate because they seem to scintillate like the Frontier. I have a modern LIP remake that I can try the experiment with.

-abe.

[LEDluvr]

Love the spock image!

Regarding the LIP remake watch, if you have some time it would make for an interesting test.

[rewolf]

...I wonder how the display of a modern LED watch would appear using the same experiment? Say, an Addidas or Majestic for example?

The Majestyk has a weird multiplexing scheme.

[abem]

Ooooh, pretty.

Hmm, it's hard to say what's going on with the Majestyk. That does look strange.

I tried the LIP remake and as expected, it's refreshing at 30Hz also, but left to right as in the Time Computer modules. It looks like the Time Computer starts with the colon followed by the digits but the LIP does the colon after the hours and before the minutes as you'd expect:



Also, this shows that on the Time Computer module, each digit flashes for only about 1 / 1200 second. It's only lit about 5% of the time, remaining dark for the rest of the time. When you look at it that way, those LEDs are impressively bright.

-abe.

[LEDluvr]

It seems these digital gems continue to fascinate us.
Thank you abem and rewolf for your "photogenic research".