Taustavalaisua

Taustavalaisua is the Finnish term for backlighting, the method of illuminating a display or surface from behind to improve readability and contrast. In the context of electronic displays, backlighting provides a uniform light source to illuminate a translucent or non-emissive layer, enabling an image to be seen without the source itself emitting the primary image.

In practice, backlighting can be edge-lit, where LEDs sit along the panel edge and light is distributed through a light guide plate, or direct-lit (full-array), where LEDs are distributed behind the screen. Direct-lit backlighting allows more uniform brightness and supports local dimming, a technique that reduces brightness in darker areas to improve perceived contrast.

Historically, backlighting used cold cathode fluorescent lamps (CCFLs), but modern displays predominantly use LEDs due to higher efficiency, longer life, and thinner profiles. LEDs also enable advanced features such as local dimming and wider color control. While backlighting is essential for LCD technology, OLED displays are self-emissive and do not require a separate backlight.

Applications extend beyond consumer displays to instrument panels, signage, and architectural lighting, where illuminating a translucent surface improves legibility or creates a desired aesthetic effect. Key considerations in backlighting include color temperature (measured in kelvin), brightness (cd/m2 or nits), and uniformity across the surface. Effective backlighting enhances perceived black levels, contrast, and color fidelity, while poor implementation can cause light bleed, halo effects, or hotspots.

Taustavalaisua remains a central concept in display engineering, balancing efficiency, uniformity, and color accuracy across devices from smartphones to televisions.