A backlight is a form of illumination used in liquid-crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination (ambient light or a special light source) to produce a visible image. How to Set Your Backlit HP Laptop Keyboard to Always On. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches, and are used in smart phones, computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild.
Simple types of LCDs such as in pocket calculators are built without an internal light source, requiring external light sources to convey the display image to the user. Most LCD screens, however, are built with an internal light source. Such screens consist of several layers. The backlight is usually the first layer from the back. Light valves then vary the amount of light reaching the eye, by blocking its passage in some way. Most use a fixed polarizing filter and a switching one, to block the undesired light.
HP Backlit Keyboard
The backlit keyboard on an HP laptop works in three states; off, time-out, and always on.
You can toggle the state via the keyboard light button. It’s pictured below. When you tap it, it toggles through its three states. Of course, the only way to tell which state it’s in is to wait and see if the light turns off.
On some HP laptops, you can go to the BIOS and change this setting. Open your HP BIOS and go to the Advanced Settings tap.
If there’s a Built-in Device Options menu there, you will find keyboard settings under it that allow you to set your backlit keyboard to always on.