EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: matthewpang on April 26, 2016, 03:18:34 am
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Hey All,
I've noticed some display delaminationissues with our Keithley instruments and wanted to see if anybody else is experiencing a similar problem. We've had this issue with several Keithley instruments now and we have sent a SMU 2450 back under warranty as it was *really* bad (very large bubbles in the screen).
See attached pictures / videos - it is difficult to capture on camera but in the photos but you can see it as the region of discoloration/distortion in the display and in the videos you can see the discoloration/distortion change as I press down on it (indicating that the a layer of the display has separated from the layer under it). This is much more obvious in person when using the instrument.
As I mentioned, our previous SMU 2450 worsened to the point of extremely large and noticeable air bubbles (almost like an *extremely* badly applied screen protector - except *in* the display ) and it was returned to Keithley under warranty (alas at that point I didn't think to take pictures of the problem). We received the replacement SMU 2450 back today and I noticed a similar (but less major) issue on the new unit's screen and checked our DMM 7510 and noticed the same.
Are you folks seeing similar issues in your units? ( I would also be interested to know if other Keithley instruments that share the same platform face the same issue)
SMU 2450 Image
(https://photos.smugmug.com/photos/i-XzkBJZf/0/O/i-XzkBJZf.jpg)
DMM 7510 Image
(https://photos.smugmug.com/photos/i-DVXWKWk/0/O/i-DVXWKWk.jpg)
SMU2450 Video
https://www.dropbox.com/s/89xaiwgqsb6p6kk/IMG_5699.MOV?dl=0 (https://www.dropbox.com/s/89xaiwgqsb6p6kk/IMG_5699.MOV?dl=0)
DMM 7510 Video
https://www.dropbox.com/s/g1qu6jk7va7d6cn/IMG_5696.MOV?dl=0 (https://www.dropbox.com/s/g1qu6jk7va7d6cn/IMG_5696.MOV?dl=0)
Cheers,
Matt
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My 2450 shows the same when turned off but I do not see it, when it is turned on.
I think it has to do with the touch screen, probably two screens are very close to each other.
It does not bother me and I don't think it is defect.
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These displays often consist of several foils, like Polarisator, color filter, reflex filters, and so on.
These are glued tightly together, in most cases, so that neither air nor humidity can cause such color fringes (optical interference between thin layers) .. That's no delamination, and no real defect, I think.
If the additional touch pad foil (resistive or capacitive) is separately attached to the display, (due to yield and production reasons), it is not glued to the display.
Maybe in this case it's sitting on a separate plastic protection cover, and there's an air gap between display and cover.
Or the touch foil is simply stretched over the displays front cover..
That may not disturb you, when the display is lit and viewed from a perpendicular angle.
Anyhow, this is not the highest quality of realization for a touch display, it's more a cheap solution, and no great expertise at Keithley how to do this correctly.
Frank