Ambient Light vs. Display Brightness – a Few Practical Tips

Each of these devices sits in characteristic spaces, which differ in, e.g., the intensity of the lighting that defines one of the crucial parameters of the LCDs, that is, brightness. Unfortunately, there is no universal recipe for display brightness adjustment – each project is different, requiring an individual approach. However, it is possible to indicate approximate values of brightness for chosen applications, which might be useful in researching the appropriate LCD. Scroll to check it out:

• about 250 cd/m² – the typical brightness of home and office equipment; 
• about 250 cd/m² – the sufficient brightness for various gaming machines, which are usually located in shady rooms (e.g., casinos) so the content presented on display will be perfectly readable;
• about 500 cd/m² – kiosks/totems set in intensely lighted interiors, e.g., shopping centers, stations and airports, public buildings such as public offices; among them, e.g., self-checkouts, ticket machines and parking meters, information points, vending machines, etc.; 
• at least 750 cd/m² – advertising media set in intensely lighted interiors, e.g., shopping centers, stations and airports, public buildings such as public offices;
• about 750 cd/m² – the optimal brightness for chosen industrial applications, e.g., HMIs; 
• about 1000 cd/m² – the optimal brightness of modules installed in the vehicles; it is worth noticing that the electronics installed in the vehicles need to fulfill a range of additional requirements, e.g., the devices used in railway vehicles should be in order with EN 50155 standard;
• at least 1000 cd/m² – outdoor applications*.

OLED displays – reliable but costly

OLED technology is relatively “resistant” to factors that might impact the readability of presented content, e.g., the ambient brightness. The OLED display matrix comprises OLEDs, which are a source of light, so they provide an infinite contrast ratio and wide viewing angle. That is why the images presented on the OLED displays are perfectly readable, no matter it is a lighted or darkened space (learn more about OLED technology).

At present, because of the “economic” issues, the OLED displays are often used in applications that require tiny screens, that is up to 5-inch. Among them, e.g., wearables such as smartwatches, household equipment such as audio/video players or coffee machines, as well as computer accessories such as printers or scanners. You may also notice them in the industry applications as screens in portable measuring devices.

EPDs – more and more popular eco alternative

In the case of EPDs (Electronic Paper Displays), you will not find in the datasheets the parameter called “brightness”. It is not determined as there is no backlight in the e-paper displays, so no emitted light. That is why EPDs are energy-efficient – they require only a bit of power to change the image. However, it causes some implications in access to the presented content. In the locations where there is no sufficiently intense source of light, e.g., after dark, the implementation of additional lighting is a must to guarantee the optimal readability of the images, e.g., a few LEDs.

On the market, EPDs are commonly used in a few niches. Although the consumers usually associate e-paper displays with e-readers, they can also notice them while shopping (e-paper price tags on the shelves) or traveling (e-paper timetables on the stops/platforms). Moreover, EPDs can also be used as advertising media – check out, e.g., AB1024-EGA, a variant of ACeP (Advanced Color ePaper), which provides images of seven colors: white, black, red, yellow, blue, green, and orange (learn more about color e-paper displays by E Ink).