OS 2.5 and contrast

[DrBibber]

Hmm... bying two of them takes 3-5 irex weeks, so in between they are maybe releasing two more updates. So better buy four :-D

Is thar mysterious waveform file hackable?

By the way, a lot of the iliad users here are Germans, why don't we have a GIUGM (German Iliad User Group Meeting) :-D

[R2D2]

from

http://www.freshpatents.com/Electrop...0050000813.php

However, the electro-optical properties of encapsulated electrophoretic displays could still be improved. Among the remaining problems of encapsulated electrophoretic displays are so-called "rapid white state degradation", a relatively rapid decline in the reflectivity of the white optical state of the display during the first few days of operation. Another problem, which is discussed in detail in the aforementioned 2003/0137521 and WO 03/107315, is so-called "dwell state dependency", which causes the change in optical state of an electrophoretic medium produced by a specific waveform to vary depending upon the time for which the electrophoretic medium has been in a particular optical state before the waveform is applied. Finally, it is advisable to make the white optical state of the display whiter and the black optical state darker.

So maybe we just went through the "rapid white state degradation"? Hmmm....

[R2D2]

I would say, that it is a wonder, that that thing does work at all.

From

http://www.freshpatents.com/Methods-...0050001812.php

[0034] It must also be recognized that, as discussed in more detail below, depending upon the number of prior states stored, the look-up tables used in look-up table methods may become very large. To take an extreme example, consider a look-up table method for a 256 (2.sup.8) gray level display using an algorithm that takes account of initial, final and two prior states. The necessary four-dimensional look-up table has 2.sup.32 entries. If each entry requires (say) 64 bits (8 bytes), the total size of the look-up table would be approximately 32 Gbyte. While storing this amount of data poses no problems on a desktop computer, it may present problems in a portable device. In another aspect, this invention provides a method for driving a bistable electro-optic display which achieves results similar to those of the look-up table method but which does not require the storage of very large look-up tables.

[0038] A challenge for achieving accurate gray scale levels in an impulse driven medium is applying the appropriate voltage impulse for achieving the desired gray tone. Satisfactory transitions between optical states can be achieved by fine control of the voltage of all or part of the drive waveform. The need for precision can be understood from the following example. Consider the case where a current image consists of a screen that is half black and half white, and the desired next image is a uniform gray intermediate between black and white. In order to achieve a uniform gray level, the impulses used to go from black to gray and white to gray have to be finely adjusted so that the gray level achieved coming from black matches the gray level coming from white. Fine tuning is further needed if the final gray level achieved is a function of prior gray level history of the display. For example, as already discussed, the optical state achieved when going from black to gray can be a function, not only of the waveform applied, but also of what state was visited before the current black state. It is then desirable to have the display module keep track of some aspects of the display history, such as prior image states, and allow fine tuning of the waveform to compensate for this prior state history (see below for more detailed discussions on this point).

[stinky ox]

That's probably why you see that purge to black when a page turns. I guess they transition to flat out black and then to the grey states from that known base. Takes a bit longer but is hella easier than retaining all that prior state info and having to calculate trajectories towards grey from arbitrary prior states.

[Roceh]

I wonder why the 'reset' state is to black though instead of to white. I assume it must be that black 'stuff' in the display is easier (hence lower power) to transition than moving the white 'stuff'.

[Alexander Turcic]

Originally Posted by DrBibber

By the way, a lot of the iliad users here are Germans, why don't we have a GIUGM (German Iliad User Group Meeting) :-D

Sounds like group therapy to me

[tribble]

OK, my contrast has definately declined with 2.5. I have a "high contrast spot" in the upper left corner of the iLiad, which gives me a whiter white and a blacker black. And thats how it used to be in 2.4. I hope its not screen degradation, and seeing all the ghosting, i am pretty sure it is not. I would say its the waveform update, thats causing the problem. Ill try to upload an image of my "hcs" later on.