An LCD display, short for Liquid Crystal Display, is a flat panel display technology that uses liquid crystals to generate images. It is widely used in devices such as computer monitors, televisions, smartphones, and other electronic devices.

 

Construction of an LCD Display:

1. Polarizing Filters: The LCD display consists of two polarizing filters placed parallel to each other. These filters allow only light waves oscillating in a specific direction to pass through.

2. Substrate with Transparent Electrodes: The two polarizing filters are attached to a substrate, which contains transparent electrodes. These electrodes are arranged in a grid pattern and are made of a transparent conductor like indium tin oxide (ITO).

3. Liquid Crystal Layer: The substrate with electrodes is coated with a thin layer of liquid crystals. The liquid crystals are organic compounds that have properties between those of liquids and solids. They can change their alignment when an electric field is applied.

4. Color Filters: Above the liquid crystal layer, there are color filters corresponding to each pixel. These filters transmit specific colors (red, green, and blue) while blocking others.

5. Backlight: Behind the color filters, a backlight is positioned. It provides the light source for the LCD display. Typically, the backlight is composed of fluorescent lamps or LEDs (Light Emitting Diodes).

 

Working of an LCD Display:

1. Polarization: The first polarizing filter polarizes incoming light waves, allowing only vertically polarized light to pass through.

2. Applying Voltage: When a voltage is applied to the transparent electrodes, an electric field is generated, which causes the liquid crystals to align in a specific direction. The alignment of liquid crystals determines the amount of light passing through them.

3. Control of Light: By varying the voltage applied to the electrodes, the liquid crystals can be twisted, allowing more or less light to pass through. This controlled light then interacts with the color filters to produce the desired colors.

4. Image Formation: By selectively controlling the alignment of liquid crystals at different locations, the LCD display can form images and display information.

 

It is important to note that most LCD displays require a backlight to be visible since they do not emit light themselves. However, there is a variation called an OLED (Organic Light Emitting Diode) display, which can produce light and does not require a separate backlight.

 

What is an LCD (Liquid Crystal Display)?

 

A liquid crystal display or LCD draws its definition from its name itself. It is a combination of two states of matter, the solid and the liquid. LCD uses a liquid crystal to produce a visible image. Liquid crystal displays are super-thin technology display screens that are generally used in laptop computer screens, TVs, cell phones, and portable video games. LCD’s technologies allow displays to be much thinner when compared to a cathode ray tube (CRT) technology.

Liquid crystal display is composed of several layers which include two polarized panel filters and electrodes. LCD technology is used for displaying the image in a notebook or some other electronic devices like mini computers. Light is projected from a lens on a layer of liquid crystal. This combination of colored light with the grayscale image of the crystal (formed as electric current flows through the crystal) forms the colored image. This image is then displayed on the screen.

An LCD is either made up of an active matrix display grid or a passive display grid. Most of the Smartphone’s with LCD technology uses active matrix display, but some of the older displays still make use of the passive display grid designs. Most of the electronic devices mainly depend on liquid crystal display technology for their display. The liquid has a unique advantage of having low power consumption than the LED or cathode ray tube.

The liquid crystal display screen works on the principle of blocking light rather than emitting light. LCDs require a backlight as they do not emit light them. We always use devices which are made up of LCD’s displays which are replacing the use of cathode ray tube.  Cathode ray tube draws more power compared to LCDs and is also heavier and bigger.