Additional questions about LCDs: Is 400 nit too bright?

khiser0001 · 05-06-2003, 09:27 AM

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!

hijinks21 · 05-06-2003, 09:40 AM

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.

khiser0001 · 05-06-2003, 09:57 AM

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: -http://www.datamodul.com/pdf/tft/DM%20UP070W01.pdf

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/AC’s transformer should be larger than the maximum lamp starting voltage.

cooljavy · 05-06-2003, 07:13 PM

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?