June 20, 2023
An LCD does not emit light; it only blocks it. An OLED pixel emits its own, so the light guide, diffuser, backlight driver and all of their cost, thickness and power disappear at once.
An LCD does not emit light; it only blocks it, which is why it needs a backlight. An OLED pixel emits its own, so the light guide, diffuser films, backlight driver and their power budget all disappear at once. What disappears with them is thickness, weight, power draw and response time. Modules can go a little over one millimetre, dark fields are pure black rather than deep grey, the view from the side does not shift colour, and switching leaves no smear.
For a battery-powered device these stack into something substantial. A wearable that needs charging once or several times a day is directly determined by the display module's power draw, while thickness and weight are close to decisive on ear-worn and eyewear products. Self-emission is not a bonus in these categories; it is a precondition.
Both technology routes are in use at these sizes. PMOLED (passive matrix) has a simple structure and direct driving, scanning line by line and pixel by pixel, which suits small displays with relatively static content — a heart-rate window, a battery indicator, status icons. Its limitation is size: as the panel grows, the time available to light each row compresses, brightness falls behind, and the scan lines become visible.
AMOLED (active matrix) has a TFT behind each pixel for individual driving, which supports higher resolution, higher refresh and better brightness uniformity. Mature solutions exist across the whole 0.42 to 2.42 inch range, suiting products with complex interfaces, animation or video. The cost is higher and the driving is more complex. That range — 0.42 through 2.42 inches — is exactly the band where both approaches cover the requirement and you choose by content complexity.
The value of self-emission has to be cashed out by the product form. Wearables and health monitoring are the obvious case: small screen, battery-sensitive, and often an always-on element. Handheld terminals and barcode scanners work in mixed lighting and need both sunlight readability and non-blinding night operation. Ear-worn devices and smart glasses have hard thickness and weight limits. Instrument clusters with always-on indicators can drop to extremely low power in dark fields showing only a few characters.
The reverse is also true. If the product is a fixed desk device with stable power and a large colour interface, a TFT LCD is likely the better buy. The microdisplay OLED advantage concentrates in four words: small, bright, efficient, thin. It only pays in the right application.
Wide viewing angle and self-emission come with the structure, but landing them in your product takes the surrounding design: a driver IC matched to the resolution, FPC length and pin definition set by the available space, partial-refresh strategy to cut refresh frequency, and sleep and wake behaviour in standby. Individually these are small; together they can account for thirty percent of battery life.
All of these can be settled during customisation. We have both PMOLED and AMOLED solutions across 0.42 to 2.42 inches, with size, interface, voltage, viewing direction, FPC and backlight configuration adjustable to the design; parameters are typical catalogue values and customisation follows your design. State the product form and the usage scenario clearly and the proposal can be right first time — which matters even more for a project that chose OLED for power in the first place.
Two requirements decide whether a PMOLED is viable or whether the product needs something else. The first is always-on operation. An always-on clock on an OLED ages the pixels that are lit, and the burn-in is permanent. Mitigations exist — shifting the display position periodically, dimming, alternating between two layouts — but they need to be designed into the application, not retrofitted. The second is outdoor readability. OLED brightness is specified at a certain ratio of pixels lit, and a screen showing dense white content cannot hold its peak figure; the effective outdoor brightness is a fraction of the headline number.
Both are testable before committing. Ask for the brightness at the actual content ratio you intend to display, and run the always-on layout for a few hundred hours to see the ageing pattern. We supply brightness measured at the content mix specified rather than the catalogue figure, and can run an ageing check on an always-on layout before the order is confirmed.
The OLED saving is structural, but the power the product draws comes from three things: content, refresh strategy and drive parameters. On the same panel, a full-white image and a mostly-dark standby screen can differ by several times in current; an always-on clock and on-demand backlight give completely different battery life.
The common engineering mistake is calculating product power from the screen datasheet and then discovering that the interface design has eaten the advantage. The correct order is to fix the operating profile first — what is displayed permanently, how often the screen lights, how bright the ambient light is — and then select the panel and drive parameters against that profile. Partial refresh, dark interfaces and on-demand backlight together usually achieve more than switching panels.
We intervene at this stage: estimating consumption from the client's interface content and advising on drive parameters. A correct panel choice paired with an unoptimised interface simply hands the saved energy back, and that class of rework is common on small devices.
Microdisplays are small enough that buyers assume they are simple to source, and the opposite is true. An OEM procurement guide for a 0.42 to 2.42 inch panel has to fix things a datasheet leaves open: the active area tolerance against the cover glass window, the flex tail length and bend, the interface (SPI, I2C or parallel), the initialisation sequence the firmware will use, and who supplies the font or the graphics library. Get any of those wrong and the first prototype will not light up.
The second RFQ item is the qualification path. A wearable and an instrument panel can use the same glass and need different evidence: drop test, humidity soak, low temperature operation, and for medical work an ISO 13485 supply chain behind the module. Ask for the test reports with the sample, not after the order, because a supplier who has them will send them in a day and one who does not will promise them for a month.
Tell us your project scenario and requirements, and we will match the right solution and provide a quote within 24 hours.
Get a Free QuoteCOG and COB character and graphic LCDs, PMOLED/AMOLED microdisplays, 0.69–10.1 inch TFT colour panels and LED backlight modules across six product families and 61 standard models. Non-standard sizes, resolutions, interfaces, viewing directions and FPC layouts developed to drawing; standard, industrial and wide-temperature grades; supplied to RoHS, REACH and CE with full compliance documentation and a 12-month warranty that can be extended per project.
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