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Questions: Segment/BL Color, TABvsZIF

Eclipze

New member
Hi... I'm a seasoned embedded designer and have developed a few applications with graphic displays, though I still have some basic questions :cool:

I am quite interested in a few hundred units of both the CFAX12864CP1-NGH and CFAX12864AP-NFH. Not sure of TAB version though. Responses appreciated.

1. Are TAB style displays soldered directly to the board?

2. LCD Segment Color
Some of the display pictures, such as the CFAX12864AP demo boards, shows the display with what appears to be blue segments, other pictures as black. I prefer black segments, and plan to have my own LED backlighting. Is this a result of the EL backlight or incorrect camera color balance?

3. LED Backlight
Can you provide an LED backlight for the CFAX12864CP1-NGH or CFAX12864AP-NFH? I don't wish to use an LCD mount on a PCB with LEDs due to total thickness.

4. Backlight Colours
Should certain backlight colours be avoided? Of interest are blue, amber, yellow and possibly red.

5. Can you supply ZIF connectors?

6. TAB vs ZIF
ZIF is more expensive and requires the additional cost of a connector, though provides serviceability. TAB is cheaper, requires a few extra capacitors and the termination of additional lines. Are there any other differences? I assume TAB must be robotically soldered for manufacture?

BTW... This is an excellent site... nicely laid out and plenty of information and pictures <thumbs up>.
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
 

CF Tech

Administrator
1. Are TAB style displays soldered directly to the board?

Yes. There is a tool available:

http://www.apecorp.com/h.htm

It is meant for re-work of pagers and the like, but could be used for small run production.

2. LCD Segment Color
Some of the display pictures, such as the CFAX12864AP demo boards, shows the display with what appears to be blue segments, other pictures as black. I prefer black segments, and plan to have my own LED backlighting. Is this a result of the EL backlight or incorrect camera color balance?


Probably an artifact of the photographing. If there is a lot of contrast between the backlight and the pixel, the pixel will appear black even though it is a dark blue. The CFAX12864AP-* are FSTN which in theory have a "color neutral" pixel (black, dark gray, etc). The CFAX12864CP-* are STN which will have a blue tint to the pixels. The color of the backlight can change the perceived color of the pixel. A white backlight will tend to make the pixels look blue, a yellow backlight will make them look closer to black.

4. Backlight Colours
Should certain backlight colours be avoided? Of interest are blue, amber, yellow and possibly red.


Blue is trouble, because the LCD has a hard time blocking it. Take a look at a typical white backlit STN negative display:

If the LCD were "perfect", this display would appear as white letters on a black background. But the STN has a hard time blocking the blue portion of th e white light, so the entire background appears blue. By happy coincidence, blue is pleasing to most people, and this combination is quite popular ;)

Amber & Yellow typically look really nice. Red is tough, sometime it looks good, but it is hard to pin down a really good combination of LCD and red backlight.

5. Can you supply ZIF connectors?

No. But Digi-Key can:

ZIF Connector for CFAX series displays

6. TAB vs ZIF . . .

Your summary is correct.

For your volume, I would recommend ZIF. We basically made the ZIF so lower volume production was not difficult.

You can do TAB on low volume, but there are many obstacles.
 
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