At the component level, liquid crystal display (LCD) modules are used to replace less efficient displays, such as cathode ray tubes (CRT). These modules do not come with enclosures and must be integrated into a larger instrument or system. LCDs belong to the non-emissive technology category, which means that they do not emit light but instead control the transmission or reflection of an external light source.
To create the display, two sheets of polarizing material are used with a liquid crystal solution sandwiched between them. When an electric current passes through the liquid, it causes the crystals to align so that light cannot pass through them. Each crystal acts as a shutter that can either allow light to pass through or block it. LCDs alter the optical path of light when an electric field is applied across the liquid crystal material.
What is the principle of liquid crystal display
To form a liquid crystal layer, LCDs sandwich a liquid crystal material between two sheets of glass. When a voltage is applied to the transparent electrodes, the liquid crystal molecules rotate in the direction of the electric field, changing their orientation to become perpendicular to the glass surface. Because different orientations of liquid crystal molecules have different optical properties, the degree of light transmission can be controlled by combining their movement with the polarization directions of the polarizers attached to both sides of the glass plate. LCDs utilize these characteristics to display images.
The composition of the liquid crystal display
LCDs are composed of many pixels, with each pixel consisting of three sub-pixels (red/green/blue, RGB). In the case of full HD resolution widely used in smartphones, there are over six million sub-pixels (1,080 x 1,920 x 3 = 6,220,800). To activate these millions of sub-pixels, each sub-pixel requires a TFT, which stands for "thin-film transistor." TFT is a type of semiconductor device that serves as a valve, providing the appropriate voltage to the liquid crystal for each sub-pixel. TFT LCDs have a liquid crystal layer between a glass substrate with TFTs and transparent pixel electrodes and another glass substrate with a color filter (RGB) and transparent counter electrodes. Additionally, polarizers are placed on the outer side of each glass substrate, and a backlight source is placed on the backside. Voltage applied to the liquid crystal changes the transmittance of the panel, including the two polarizers, altering the amount of light passing through the front surface of the display from the backlight. This principle enables TFT LCDs to produce full-color images.
Composition of the liquid crystal display
Medical LCD PCBs refer to printed circuit boards that are specifically designed for use in medical-grade liquid crystal display (LCD) monitors. These PCBs are essential components in medical displays as they provide the necessary electrical connections between the display components, including the LCD panel, backlight, and control circuitry.
Medical PCB must meet stringent requirements to ensure their safety and reliability. They are designed to withstand harsh medical environments, including exposure to moisture, temperature fluctuations, and electromagnetic interference. They must also comply with strict medical regulations, including ISO 13485 and FDA guidelines.
In addition to meeting safety and regulatory requirements, medical LCD must also deliver high-quality image performance. They are optimized for image clarity, contrast, and color accuracy, and are designed to minimize image lag and distortion.
Overall, medical LCD PCB play a crucial role in ensuring the accuracy and reliability of medical displays used in diagnostic and surgical applications.
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