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EPD Source codes and Documentation
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picture vanish #7

Closed holger123 closed 9 years ago

holger123 commented 10 years ago

I use the 144px epaper display on the MSP430 Launchpad. I could download the demo SW. But the cat picture vanished half in the time when the display power is down. What could be the error?

Holger

hxw commented 10 years ago

Can you give some smore details? Such as which version of EPD board, direct connectuon or are you using a ribbon and you are using the latest demo.ino (DEMO_VERSION "2")

I just tried with a EPD-05 board and LaunchPad using direct connection wait for text display to finish an cat to be displayed, the pulled out USB power. (display should be powered down and discharged while red LED is flashing) The picture is still OK.

Is your picture fading only when power is removed or even when red LED is flashing? (possible to attach a photo?)

A possible cause is that the discharge circuit is not working - are you able to check if the discharge pulse is occuring and that the capacitors are discharging properly?

holger123 commented 10 years ago

Hello, I recognised that the demo reacts on light. Under my lamp it doesn’t work at all. I can send you an video per email.

Regards Holger

hxw commented 10 years ago

Today is very sunny, so I moved the 1.44" device into direct sunlight.

  1. with an already displayed image I saw no effect on its image.
  2. with the demo running the cat image would clear instantly at the end of the display sequence.
  3. shadowing the display would make it operate correctly

The 2.0" display tended to go black during the same test and was more sensitive, simply shadowing with my hand only produced less darkening. It had to be move further from the window

I think that duplicates the effect you are seeing. I will contact the engineers for their advice.

holger123 commented 10 years ago

Hello Christopher, any new on this?

Regards Holger

From: Christopher Hall [mailto:notifications@github.com] Sent: Mittwoch, 27. November 2013 02:45 To: repaper/gratis Cc: Schmerling, Holger Subject: Re: [gratis] picture vanish (#7)

Today is very sunny, so I moved the 1.44" device into direct sunlight.

  1. with an already displayed image I saw no effect on its image.
  2. with the demo running the cat image would clear instantly at the end of the display sequence.
  3. shadowing the display would make it operate correctly

The 2.0" display tended to go black during the same test and was more sensitive, simply shadowing with my hand only produced less darkening. It had to be move further from the window

I think that duplicates the effect you are seeing. I will contact the engineer fo their advice.

— Reply to this email directly or view it on GitHubhttps://github.com/repaper/gratis/issues/7#issuecomment-29353891.

hxw commented 10 years ago

Holger, can you try with the patch I just committed - the engineer found my bug

hxw commented 10 years ago

Another question: do you have some kind of bezel around the display?

I found that the light level appear to affect the COG when it is directly exposed; normally this would be covered by the display bezel or the device's case. If you are running with the whole board uncovered under the lamp, try covering the the COG.. I used a metallic-silver paint pen to paint on Scotch 3M tape, made a double layer of this, cut out a rectangular piece sufficient to cover the COG (about 5mm x 15mm). With that in place and the above fix the display was operating correctly only 5cm from the lamp.

Hope this helps.

holger123 commented 10 years ago

I used the fix and a tape bezel around the display now. The seen behavior improved but still some effects under a lamp still exist.

Regards Holger

From: Christopher Hall [mailto:notifications@github.com] Sent: Sonntag, 8. Dezember 2013 07:49 To: repaper/gratis Cc: Schmerling, Holger Subject: Re: [gratis] picture vanish (#7)

Another question: do you have some kind of bezel around the display?

I found that the light level appear to affect the COG when it is directly exposed; normally this would be covered by the display bezel or the device's case. If you are running with the whole board uncovered under the lamp, try covering the the COG.. I used a metallic-silver paint pen to paint on Scotch 3M tape, made a double layer of this, cut out a rectangular piece sufficient to cover the COG (about 5mm x 15mm). With that in place and the above fix the display was operating correctly only 5cm from the lamp.

Hope this helps.

— Reply to this email directly or view it on GitHubhttps://github.com/repaper/gratis/issues/7#issuecomment-30076331.

hxw commented 10 years ago

There is currently no plan to make bezels, cases or thing like that since these items will depend on the final product being made.