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Additional questions about LCDs: Is 400 nit too bright?

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  • Additional questions about LCDs: Is 400 nit too bright?

    I know I am asking alot of questions regarding LCD displays but it is one of two areas of the system that I feel that my lack of experience will hurt the project if I choose poorly. (So I am asking lots of questions to avoid that!)

    I found a 7" LCD Module that comes with everything that I need to make it work (controller, input leads) and am wondering about the specs. I am wanting to ensure that I can see the display during the day so I was told to look for monitors with a higher than 250 nit rating.

    Is 400 nit rating too high? What do you guys think of the following specs:

    Resolution (pixels): 1440 x 234
    Active Area (mm): 154.08 x 86.58
    Screen Size (Inches): 7.0" Diagonal
    Dot Pitch (mm): 0.107 x 0.370
    Color Configuration: RGB V Stripe
    Overall Size (mm): 166 x 100 x 6.79
    Backlight: "L" Shape CCFL
    Input Voltage: 5 VDC
    Contrast Ratio: 150/1
    Brightness: 400 nit

    This is for a unipac UP070W01 LCD module (The vendor that I might purchase from sells a complete kit with everything)

    Please share your experience with me. Once I get this down the other area of concern is powersupply including startup and shutdown circuit. Other than that I am ready to go.

    These forums are great but there is allot of varying opinions on the two topics that I have questions about and I am trying to narrow it down.

    Thanks in advance for all of your help!

  • #2
    if you can adjust the brightness it would work great. I have a 250nit screen and sometimes that is too bright for me at night.
    '98 Explorer Sport (down atm)
    AMD 800mhz 192megs RAM 60gig hard drive 9 inch widescreen VGA
    80% done


    • #3
      I just spoke with the vendor and it looks like this screen will not work also as the operating temp is only 0C which I believe is 32F

      Looking at the manual: -

      It states that I can adjust the brightness by "The brightness of LCD panel could be changed by adjusting the AC component of
      VCOM." I assume that there is some way to maybe tie this to a dimming switch or even to the cars dimmer?

      What I do not understand is the Note number one below. If I am reading correctly the lamp could not be started in temps under 25C or 77F?:

      c. Backlight driving conditions
      Parameter Symbol Min. Typ. Max. Unit Remark
      Lamp voltage VL - ( 580 ) ( 638 ) Vrms Note 3
      Lamp current IL - ( 6.5 ) ( 7 ) mArms Note 3
      Frequency FL - 60 80 kHz Note 3,4
      Lamp starting volt. VS - ( 930 ) ( 1150 ) Vrms Note 1,3,5
      - ( 1100 ) ( 1400 ) Vrms Note 2,3,5

      Note 1: Ta = 25C
      Note 2: Ta = 0C
      Note 3: Reference value, correct value is subject to final backlight specification which will be decided in the future.
      Note 4: The lamp frequency should be selected as different as possible from display horizontal synchronous signal to avoid interference.
      Note 5: For starting the backlight unit, the output voltage of DC/ACís transformer should be larger than the maximum lamp starting voltage.


      • #4
        I believe that is a problem with all the lcd's (cell phones, pda's, etc) but after your car warms up a little you should be all set.

        Oh, I forgot, How much are you getting the LCD for? any links to the vendor?