Touch screen modification on PRS 700 for improved clarity and contrast

[gokalp]

I was posting my progress in the disassembly thread, but I figured it might be a good idea to form a separate thread for the touchscreen modification. So here is the breakdown, I have accidentally damaged the touchscreen on my PRS 700 trying to clean the dust spots. Sony told me that the replacement panel would be $199.38, so I tried modding the reader with a standard resistive touch panel.

It turns out that the loss of contrast in the screen is mostly due to the digitizer, which also forms the topmost protective layer. Its texture is pretty matte to prevent reflections.

I have ordered a 6.4" resistive digitizer from Mouser:
http://www.mouser.com/Search/Product...4DJrRFjNIx0%3d
It's $29.92, but it transmits 86% light compared to the standard 80%. One problem though, since it is 6.4" and not 6". Hence, it will not fit unless one would trim the sides by a couple of millimeters, which not so easy as the panel is glass. Here is datasheet for the digitizer family: http://www.fujitsu.com/downloads/MIC...rd_ds_rohs.pdf
and the datasheet for the specific model:
http://www.fujitsu.com/downloads/MIC...-0554-t048.pdf.

The panel has arrived, and it required a little bit of retrofitting. I knew that the cable was the same as the original Sony panel, both in terms of size and cable arrangement. However, when I opened the device I saw that in the last centimeter, the cable gets smaller and plugs into a miniature connection. Anyways, I cut the original cable, cleaned up the protective plastic and soldered both connections.

Note that I also cut the front plastic, only the gray bezel (i.e. the frame with the text "home", "search" etc...) remains. This also improved the screen.

The panel worked immediately, even without any calibration. And after the calibration it became even better. A couple of observations, the panel is on glass, it is glossy and it is *very* clear. It works excellent with a finger, and not so much with the stylus, as I think the stylus cross section is too small to register as a touch.

I tried putting the panel behind the reader, facing the back cover. It works, and it is not really difficult to operate, but it also registers a lot of false touches while holding the reader, so I gave up on that. However, I really like the clamshell type design, where I can move the digitizer to the back when needed.

BTW, when the e-ink screen is exposed without any transparent sheet, the lighting does not work. However, the external digitizer fixes this problem perfectly, and even enhances the light uniformity. Originally the reader has a clear light gradient which made the center darker. This is due to the reflective surface being too close to the screen. With the external digitizer, the space between the screen and panel increased and this made the light much more uniform.

So here are the pros and cons of the flippable touch panel:
Pros:
- Excellent clarity and contrast without the touch panel, as much as 505
- Much better clarity and contrast with the touch panel compared to original design.
- Touch panel very easy to operate with finger, this includes slidebars and keyboard.
- Much better light uniformity with the touch screen.
- Much easier to remove the dust

Cons:
- panel does not fit in the front recessed section as it is 5mm larger on either side (which makes this mod flippable)
- glossy touch panel means it might create reflection problems in certain situations. (but you can flip it over to read with the digitizer stored on the back)
- Stylus not working with the digitizer.
- Light dies not work without a panel on the front of the screen (i.e. digitizer or a clear plastic sheet)

Here are some pictures if anyone is interested.

The screen clarity with and without the bottom part of the original digitizer:
Note that in this picture, the left side has the bottom and top digitizer, however the right on only has the top screen.


The screen with the digitizer stored in the back:
Here I cut the top screen such that only the gray bezel remains.


The illumination without and with the external panel:


The reader with the touchscreen on, and an image of the ribbon cable.

[daffy4u]

I love people who are ingenious to try this stuff. I don't have a Sony but I enjoy reading about all the various mods to all the readers. Great job!

[shighfield]

Amazing. I may have to do this if I ever get the reader back as I"m sure the dust will appear again.

Originally Posted by gokalp

Here are some pictures if anyone is interested.

The screen clarity with and without the bottom part of the original digitizer:
Note that in this picture, the left side has the bottom and top digitizer, however the right on only has the top screen.


The screen with the digitizer stored in the back:
Here I cut the top screen such that only the gray bezel remains.


The illumination without and with the external panel:


The reader with the touchscreen on, and an image of the ribbon cable.

Your URLs are not showing up here. Would love to see what you've done.

[gokalp]

Originally Posted by akira28

Your URLs are not showing up here. Would love to see what you've done.

I have uploaded the images to Picasa, you should be able to view them here:
http://picasaweb.google.com/gokalpm/Reader#

[JSWolf]

That is a very nice job. Well done!

Really nice work. But in a way it is disappointing in that now we know that the 700 could have been a much better reader.

How are you securing the new digitizer to the front and, when it is swung to the back?

[Server]

There must be other digitizers that will fit since you're only off
by 5mm I'm wondering if someone like FOXCONN or other supplier
can come up with the right spec. Obviously, the upgrade would be
worth while only if the fit is seamless. ie. enhanced display!

Personally, I don't have a serious issue with the screen but if a
workable digitizer comes to fruition, then I'd mod my unit without
blinking.


Thanks gokalp!

[sthorpe]

I agree with Server. Less Fogginess would make the 700 a top notch reader instead of middle of the road.

[el.astrologo]

Gokalp you rule!
Now, that's what I was talking about!
Great work man, my hat is off to you

if only "someone" were to post a videotutorial for those of us who are electronicly impaired

[lilac_jive]

Did you send this to Sony by any chance? Maybe they would like to see this.

[Server]

They're already watching....

[lilac_jive]

Originally Posted by Server

They're already watching....

Well I know that...but are the designers?

[gokalp]

Thank you everyone for your kind words.

akira28, that is a very good question to ask. I am currently using some double sided sticky tape to hold it. But my ultimate plan is to use a little bit of velcro, which should be both sturdy and easily removable. Though I did not have time to look around yet.

Server, I actually found a better sized digitizer at Digikey. It was 5.88" and the transparent window was bigger than the e-ink screen. However, it was out of stock, and was a special order if I remember correctly. So I had to research more, and found this screen as the next best thing.
As for the modification, I would have been a little bit more hesitant if I did not damage the original digitizer. I knew the PRS 700 screen was not as good as PRS 505, but still it looked very good to me. Now, it looks even better

el.astrologo, I would like to do a videotutorial, but currently I am really busy as I am trying to finish my doctorate degree earlier than expected.
I used the excellent disassembly guide by igorsk, and it nicely shows the related screws and brackets to be removed.
The modification is not difficult really, and it only requires soldering on 4 1mm copper strips. I can take some more photos of what to expect there, to help anyone interested.

lilac_jive, to be honest I do not know who to contact, or whether they would be interested at all. I am sure they have their reasons for making the current decisions, and I would be extremely surprised if they did not try these off the shelf screens already...

[Server]

Originally Posted by gokalp

I was posting my progress in the disassembly thread, but I figured it might be a good idea to form a separate thread for the touchscreen modification....

The screen clarity with and without the bottom part of the original digitizer:
Note that in this picture, the left side has the bottom and top digitizer, however the right on only has the top screen.


The screen with the digitizer stored in the back:
Here I cut the top screen such that only the gray bezel remains.



I was pondering your idea on using the touch panel on the back
in order to use the reader with the naked eInk exposed to have enhanced
contrast. The new interface, forces the use of the touch panel, but
there is no reason why button mapping can't be re-assigned with
a new firmware in order to re-program buttons to navigate the home
screen.

The HOME button can have a DUAL function. While in read mode, selecting
HOME would bring you back to the HOME screen. And using the arrow
buttons, would navigate around books or the Home screen, while the HOME
button could act as a SELECT button (only while in Home screen)
Thereby, eliminating the need to use the touch panel on the back
of the reader. Of course, input search and notes would be an issue
unless button re-mapping could also be used to select letters.

The feesability of this must be studied but once a ROM gets out, it
would be interesting to see if this can be achieved.