Especially in the tech sector, if you want to know where you are going, it’s good to know where you came from. In this week’s summer school lesson plan is a quick history of the evolution of organic light emitting diode (OLED) display driver integrated circuits (DDIC) technology.
OLED displays are becoming commonplace, particularly in smart phones, favored by design engineers for its ability to deliver dynamic colors and high contrast ratio for great readability even in sunlight. Further, these displays are responsible and flexible/bendable. More and more, buyers will find suppliers of these and related technologies on their bill of materials (BOM).
Let’s take a look at the development timeline for this fast emerging technology.
2000 - 2005
In the early and mid-2000s, OLED display entered the market first with a two-inch range PM OLED sub display of a feature phone, in which the OLED DDIC employed a low-resolution passive current driving method. In the passive current driving method, the core technologies of DDIC included output current matching, controllability and high current consumption control. This was a period of time when -- despite several advantages of an OLED panel -- its high drive current and voltage caused PM OLED and DDIC to face technical challenges to enter the 3-inch or larger main panel market. Therefore, the industry began to address these issues in order to become more competitive with LCD displays.
2006 to 2010
From roughly 2006 to 2010, OLED displays entered the feature phone main display market with the development of the qVGA AMOLED display, which marked the first real competition for LCD. At this point, the OLED DDIC adopted an active voltage driving method, which enables the source output voltage and the controllability of panel voltage noise to improve OLED image quality.
This first- generation core technology was also the first to benefit from lower cost mass production capability. This first-generation core technology marked an evolution in several DDIC characteristics. For instance, at that time existing OLED pixels used a current driving method, but newer-generation DDIC was required to adopt a voltage driving method to achieve higher resolution and realize lower power consumption.
This in turn led to a significantly reduced “non-uniformity” of the pixel circuitry, which converts voltage into current and results in much better noise sensitivity, as compared to an LCD display of an equivalent resolution. To realize completely OLED’s advantages in faster response time, higher contrast ratio and excellent color reproducibility and naturalness, the DDIC was required to perform several times greater output accuracy and noise controllability than an LCD DDIC.
To achieve this, it was inevitable that the OLED DDIC would grow in complexity and size. However, the industry addressed this seeming disadvantage by successfully developing lower-cost mass production techniques for AMOLED DDICs used in mobile phones and Portable Multimedia Player (PMP). This development enabled the first-generation core technology to become truly competitive with LCD and positioned it well for opportunities to expand the OLED market.
2011 to 2014
With the proliferation of smartphones from the mid-2010s, high-resolution displays were adopted in earnest and the consumption of video content increased. This brought to consumers a widespread recognition of the advantages of OLED displays, including lower power consumption as compared to the first OLED displays.