Interactive compensation for differential ageing in P(O)LED display
Publication Date: 2002-Mar-25
The IP.com Prior Art Database
Interactive compensation for differential ageing in P(O)LED displays
To avoid coloration in P(O)LED displays
P(O)LED devices degrade during operation, resulting in a change (usually a reduction)
in light output at a given current density. In colour displays this degradation process results in
coloration ("white" is no longer white, but has for example a green shade), if the degradation
of the individual colour components have different degradation rates. This effect is
unacceptable and must be minimised in production displays.
Here, we propose a more simple method for compensation of the coloration. The
relative brightness of the individual colours can be set by the user by means of an external
function that is capable of changing the current for the three colours. Visual inspection by the
user is applied as a monitor for the quality of the colour of the display.
The external function can not only be used to compensate for differential ageing, but it
can also be used to set the colour of the display to the individual wishes of the user.
In order to avoid over-stressing, resulting in a short operational lifetime of the device,
the external function can only adjust the relative current of the pixels. The total current for the
three colours is kept constant.