Choosing an OLED Display Module

Display modules come in a variety of flavors: LED, organic LED (OLED), quantum dot LED (QLED), and the ever-popular LCD. We’ve come a long way since the advent of the 7-segment display, and new product designers have plenty of options to choose from when adding a display to their system. Here’s what you need to know about OLED display modules for your next product.

LED vs. OLED Display Modules

Compared to LED displays, OLEDs offer comparable resolution, dynamic range, and color depth, yet OLEDs offer higher contrast without the need for backlighting with an array of white LEDs. OLEDs consume less power than an LED LCD display as there is no need for backlighting, allowing the brightness in an OLED display to be tuned to produce the desired contrast. Some LED or OLED displays can also provide touchscreen functionality for HMI, either as a capacitive or resistive touch screen.

If you’re looking for an OLED display module for an IoT device, infotainment product, or other system that requires HMI, here are some points to consider:

• Power consumption. An IoT or mobile device may run on battery power, and you should consider the power consumption and determine how long the device can run between recharging.
• Touchscreen capabilities. As was mentioned above, your OLED display module might need touch screen capabilities in order to provide user interaction. Using a touchscreen OLED display module eliminates the need for a keypad.
• Bit depth. The bit depth tells you the number of different color levels that the module can display per color channel. Think of this as the number of different color shades the device can display. As an example, an 8-bit RGB display can produce (2^8)^3 = 16,777,216 unique colors.
• Resolution. The resolution (i.e., the fineness of the image on the screen) is determined by the number of pixels in the display. More pixels in each direction generally means higher resolution and finer images. Note that there is a tradeoff between size and resolution; if a large and small display have the same number of pixels, the smaller display will produce a finer image. This is why pixels per inch (PPI) or pixel pitch is a better indicator of image quality than simply looking at the number of pixels.
• Active vs. passive matrix. A passive matrix OLED display module uses an array of perpendicular cathode and anode electrodes to provide addressing and illumination. In contrast, each pixel in an active matrix OLED display module uses a thin-film transistor (TFT) to switch it on or off. The TFTs in an active matrix display consume less power, making them a better choice for larger displays.
• Display size. This is normally measured diagonally across the display area.

Small-sized OLED Display Modules

The OLED display modules presented below are not intended for new televisions. Instead, they are ideal for infotainment systems, wearables, mobile devices, and other applications that require some level of HMI.

Microtips Technology MTD0550AZOM-T-3

The MTD0550AZOM-T-3 active matrix OLED display module from Microtips is ideal for smaller infotainment systems or other systems that require a high resolution capacitive touch screen display. This module provides a 68.299 mm x 121.421 mm viewing area with 8-bit RGB channels and 1080 x 1920 pixels (0.0632 mm pixel pitch). This module includes an integrated driver IC with a 4 lane MIPI interface.

Microtips MTD0550AZOM-T-3 active matrix OLED display module block diagram. From the MTD0550AZOM-T-3 datasheet.

Newhaven Display NHD-1.27-12896G

The Newhaven Display NHD-1.27-12896G OLED display module is ideal for wearable devices or other small displays. Although the pixel resolution appears low (128 x 96 pixels), it has ~0.2 mm pixel pitch and can still produce high quality images. The module is only 1.6 mm thick and includes a flex connector. It includes an SSD1351 controller directly on the module and uses a parallel or serial MPU interface. This particular module uses 6-bit RGB display, providing 262,144 unique colors.

NHD-1.27-12896G OLED display module front and back, from Newhaven Display.

4D Systems UOLED-96-G2

The UOLED-96-G2 OLED display from 4D Systems is a rather small passive matrix OLED display module (0.96 in. viewing area) with 96 x 64 pixels. However, the pixel pitch is ~0.2 mm, making this OLED display module competitive with others on the market. The rated power dissipation is only 1 W at 4.0 to 5.5 V supply voltage (5.0 V nominal). The electrical connections on the pack are provided through pins, so this module is not the best choice for wearables. It includes an embedded Goldelox graphic display processor/controller and a microSD card slot. It also provides a 3.3 V output for powering external circuits.

Image of the UOLED-96-G2 OLED display module, from the UOLED-96-G2 datasheet

If you are looking to build a much larger OLED display than the options presented here, many companies are producing transparent video wall OLED displays that provide impressive resolution and beautiful images. If you’re looking for more specialized display modules, you might consider a QLED display in the future as costs for these modules come down. As new IoT products are created for automating all areas of modern life, you’ll need the right tools to determine which displays and supporting components you’ll need to support your display. Try using our Part Selector guide to determine the best option for your next product.

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