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?