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I'm working on a product with a vendor/factory and they've sourced two difference LCD's. One has a darker contrast. We chose the one with the darker contrast because it is easier to read.

However, according to the vendor, they said that variation in production will give us different darkness for the same LCD.

So, today, I received 3 pre-production samples and indeed there was variation in the darkness. One was too dark so that at certain angles the digits were a little hard to read.

Is there a way for them to adjust this? Can they just change a resistor somewhere or put an adjustable potentiometer somewhere? (I read that the bias voltage or the contrast voltage can be adjusted)

Are there LCD's out there where adjustment is not possible?

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All LCD's can be factory tuned for contrast brightness and range. These are set by the voltage references for "black" "white" voltage references on the LCD and the video signal gain and offset. Each design is unique in how stable the voltage references are and what they need to be to match production variances.

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  • \$\begingroup\$ do you think the factory can tune each LCD or am I stuck with this variance? \$\endgroup\$ – milesmeow Nov 28 '12 at 7:23
  • \$\begingroup\$ If you dont have a spec like 100:1 contrast ratio then no hope. Otherwise yes \$\endgroup\$ – Sunnyskyguy EE75 Nov 28 '12 at 8:03

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