-P-

Term (Acronym) [units]: Definition

Passive Matrix (PM): Used in reference to both LCDs and OLEDs, passive matrix refers to the drive architecture where only the data and gate lines are controlled. PM displays have lower performance and higher power consumption than active matrix (AM) displays.

Passive Matrix LCD (PMLCD): An LCD that uses a passive matrix drive scheme. A pixel in a PMLCD must maintain its state without active driving circuitry until it can be refreshed again.

Passive Matrix OLED (PMOLED): An OLED that uses a passive matrix driving scheme. Almost all OLEDs as of mid-2006 are PMOLEDs because there are some difficult problems still to be solved in creating an AM backplane that works well with current-driven OLEDs (as opposed to voltage-driven LCDs).

Patterned Vertical Alignment (PVA): Samsung’s version of VA technology that adds an etch step to create alignment patterns without using any protrusions. The performance is generally the same as MVA except that the contrast ratio is higher.

Percent of NTSC: The degree to which a display can reproduce the range of colors defined in the 1953 NTSC television spec. Standard LCDs today range from about 45% to 75% of NTSC. LCDs with enhanced CCFL backlights can reach 90%; LCDs with LED backlights can exceed 100%.

Persistence of Vision: The characteristic of the human vision system that allows a series of images displayed in quick succession to be perceived as motion rather than a series of individual frames. The same characteristic allows the interlaced frames of a TV signal to appear as a single image.

Personal Digital Assistant (PDA): A type of small personal computer, mobile and with limited functionality compared to a regular PC. PDA displays are usually in the 3" to 3.8" range.

Phase-Alternating Line (PAL): A European and international broadcast standard for video and broadcasting. PAL is higher resolution than NTSC (625 lines vs. 525 lines).

Phosphor: The coating on the inside of the screen on a CRT, PDP, FED (Field Emission Display) and SED (Surface-conduction Electron-emitter Display). Phosphors glow when struck by electrons; images appear on the screen by controlling when and where electrons hit the phosphors.

Phosphorescent OLED (PHOLED): An OLED that uses the principle of electrophosphoresence to convert up to 100% of the electrical energy in an OLED into light, versus the 25% that’s typical of a standard OLED.

Photolithography: A process in display and semiconductor fabrication that transfers a pattern from a photomask to the surface of a substrate. Photolithography involves a combination of substrate preparation, photoresist application, soft-baking, exposure, developing, hard-baking and etching.

Photomask: As used in photolithography, a photomask is a transparent blank covered with a pattern that is transferred to the surface of a substrate through photographic methods.

Photoresists: Light-sensitive coating applied to a substrate or board, exposed, and developed prior to chemical etching; the exposed areas serve as a mask for selective etching.

Physical Vapor Deposition (PVD): A deposition method commonly used for metal layers through bombardment of target by gas plasma, often called "Sputtering".

Pitch: The center-to-center dimension of adjacent pixels, dots, printed circuit board traces or connector holes.

Pixel: Shorthand for Picture Element, the smallest bit of data that makes up an image. A pixel is composed of three subpixels, one red, one green and one blue. Each subpixel is energized to different intensities, creating a range of colors perceived as the mixture of the subpixels.

Pixel Anomaly: A pixel that displays only one color (white, black, red, green or blue). These are commonly referred to as "stuck" pixels. A small number of pixel anomalies is considered normal in an LCD; the number of anomalies it takes for a display to be considered defective varies by hardware manufacturer.

Pixel Clock Speed: The frequency at which individual pixels in an image are written to the screen.

Pixel Pitch: The distance between pixels on a flat-panel display, measured from the center of one subpixel to the center of the adjacent subpixel. The term "dot pitch" is also used (incorrectly) for this distance, where "dot" refers to the electron beam spot on a CRT.

Pixels Per Inch (PPI): The number of pixels in one horizontal inch of a flat-panel display’s surface. The term Dots Per Inch (DPI) is also used interchangeably (but incorrectly).

Plasma Display Panels (PDP): A type of flat panel display based on plasma technology, which employs the principles of fluorescent lighting. In plasma displays an electric field passes through a gas that is maintained at a low pressure inside a glass tube. The electric charge ionizes the gas, which changes state, becomes plasma and gives off ultraviolet radiation. The radiation strikes the outside of a glass tube coated with phosphor, causing the phosphor to produce visible light.

Plasma Enhanced Chemical Vapor Deposition (PECVD): A CVD process that uses gas plasma to enhance the chemical reaction rates of the precursor (intermediate) materials through disassociation. PECVD allows deposition at lower temperatures, which is often critical in the manufacturing of a display. PECVD is commonly used for Si and ITO layers.

Polarization: The property of electromagnetic waves (such as light) that describes the direction of their transverse electric field. Light waves can be linear polarized with the e-field in a single constant direction, or circular polarized with the e-field rotating like a left- or right-handed corkscrew.

Polarizer: A linear polarizer is a filter that changes normal light (where the e-field goes in all random directions) into light where the e-field goes in a single direction. A circular polarizer is created by laminating a 90-degree retardation film to a linear polarizer.

Polyethylene Naphthalate (PEN): A polyester film that is quite similar to PET but which is more temperature-resistant. It also has better UV resistance and barrier properties. However, it is more expensive and has less flex life.

Polyethylene Terephthalate (PET): A thermoplastic polymer resin of the polyester family. It is most commonly used in its amorphous (transparent) form. 30% of the world’s production of PET is consumed by beverage bottles. PET is used as the top surface of resistive touch screens. Mylar, invented by DuPont, is made of biaxially oriented PET film (boPET).

Polyimide (PI): A transparent polymer used as a base film for the alignment layer in an LCD; also used in opaque form as the base for flexible circuits (e.g., Kapton® from DuPont).

Polymer Light-Emitting Diode (PLED): A form of OLED made with organic polymer compounds. PLEDs are solution-processable, which allows them to be applied to substrates using techniques such as inkjet printing.

Polycrystalline-Silicon (p-Si): Silicon material that has a crystalline structure, but not regular, and exhibits boundaries between grains; the semi-conducting material in p-Si active matrices. Often shortened to "Poly-Silicon".

Polyvinyl Alcohol (PVA): A water-soluble synthetic polymer film used in the manufacturing of polarizers.

Portrait Mode: A screen oriented such that it is narrower than it is tall.

Premium MVA (P-MVA): Same as MVA except that the pixel response time is improved, although it’s still slower than TN.

Printed Circuit Assembly (PCA): A printed circuit board after it has been loaded with electronic components. Sometimes appears as Printed Circuit Board Assembly (PCBA).

Printed Circuit Board (PCB): A substrate used to hold and interconnect electronic components. Made up of one or more conductive layers separated and supported by layers of insulating material that are laminated together.