LCD Structure

Liquid Crystal ("LC") flows like a fluid, but like its namesake can have molecular alignment like a crystal (solid) in optical clarity. TN, STN, and FSTN configurations utilize nematic type LC fluid. Nematic (Greek Origin: "Nema" meaning thread) can be electrically-driven to form thread-like orientations to align towards a predetermined axis. Paring this capability with top and bottom polarization film allows only specific light to pass or become blocked by the top polarizing film layer. The technology can operate off of ambient light an entirely reflective material behind the display and optionally include a light source beneath the panel with transmissive or partially transmissive properties. The term "transflective" is often used for partially transmissive and partially reflective backing material.

Photolithography

Photolithography is a common process for optical electronics of putting transparent circuitry on glass substrate. The circuit is a fine layer of Indium Tin Oxide ("ITO") which serves as conductive circuit on the glass with minimal observability. The process is performed in a cleanroom under light-sensitive conditions. The general process includes application of photoresist to determine where ITO is allowed, controlled exposure and development baking stage, and removal of the photoresist materials. There are many cleaning stages throughout this process. Patterns on the glass for LCD can be made into graphical arrays, alphanumeric arrangements such as 7-segment or 5x8 groupings, or into fully customized icon designs and shapes. Our factory can support full customization of these designs in addition to select public offerings.

Polarization

Polarizer films are essential to the operation of LCD products. Depending on the construction and specifications, LCDs may utilize linear or circular polarizer films. Linear polarizers are necessary for twisted nematic type LC fluid designs and are configured in pairs with specified offset angles. Common polarizer offsets include 90° and 270° for TN and STN technologies respectively. The origin angle is arbitrary to the design and often may be skew to the panel to avoid interference with polarized eyewear of end-users. Polarizers may also be configured in positive or negative modes. The negative mode will require a light source behind the panel for viewing and will be exclusively transmissive in nature to prevent reflection of ambient light and dark inactive area. The positive mode will be able to utilize ambient lighting and have lighter color inactive area such as silver, gray, or yellow-green coloring depending on the materials selected.

IC Bonding

LCD products may be directly driven by a customer processor, but many panel designs will have substantial quantities of pixels or segments to multiplex. For this consideration, many designs will incorporate an application-specific integrated circuit ("ASIC"), commonly just referred to as the display driver IC. These ICs must be paired to provide the correct number of segments & commons for drive of the panel and equally provide the correct power and drive techniques for avoiding accumulation of charge in the panel structure. Display drivers can support various interface protocols and standards. These semiconductors can be bonded by Chip-On-Glass ("COG"), Chip-On-Flex ("COF"), and Chip-On-Board ("COB") bonding methods. Most modern displays are migrating towards compact COG driver packages for cost efficiency.

Interconnect Bonding

Custom LCD solutions may have various interconnection options for your system. ITO glass can have conductive pads on the glass edge that may be paired with elastomeric conductive strips and compression of the glass with a printed circuit board. Equally, the display can have a bonded interconnection option. Bonded connections can include pins and flexible printed circuit ("FPC") designs. FPCs are a popular method for many display products for smooth system assembly and post-production equipment repair and maintenance support. Flex-to-glass bonding is accomplished with Anisotropic Conductive Film ("ACF") that is a durable conductive adhesive between the glass and film attachment area. After bonding, it is common for electrical insulation, limiting environmental exposure, and strain relief material to be applied over the bond area on the glass and FPC. Common material for securing the bond area include Room Temperature Vulcanized ("RTV") silicone which allows for improved quality in storage, handling, and subsequent module integration processes.

Backlighting

LCD technology is able to operate without backlighting if ambient lighting conditions are sufficient, but backlights are often needed for low-light conditions. The primary backlighting technology is light emitting diode ("LED") technology. Fluorescent lamps have been primarily abandoned for this type of appliation due to RoHS and REACH global environmental initiatives. Electroluminescent ("EL") are still available, but are less common for many applications due to their alternating current power supply requirements. LED backlights are optimal for direct current drive and simplified power supply requirements. LED backlights primarily use light guides to optically diffuse the light across the surface area of the LCD. Light boxes are internally reflecting, have rear reflection gradients based on LED arrangement, and have diffuser and/or brightness enhancement film ("BEF") layers for uniformity and blending purposes. Premium materials can combine these film layers for lower light attenuation. Fiber-optic backlight diffusers are also possible, but may come at a cost premium.

Module Assembly

Liquid Crystal Modules ("LCM") are quite popular combining LCD panels with backlighting, frames, and driving electronics. Our factory has some industry standard module designs, but the majority of LCD panels we supply are customized to varying degrees in panel and module requirements. Some applications may seek additional value-added user-interface ("UI") needs including buttons, touchscreens, temperature or other sensors, cameras, and other system components adjacent to the display. Our factory is able to integrate the displays from simple modules, UI subassembly, reaching complex full box builds or enclosed monitors. LCM designs are often much more affordable and impose less minimum order quantities than other display technologies. Our ability to offer module designs that are easy for system integration and optimal performance is part of OSD Displays value proposition.

Quality & Packaging

At the end of our assembly, the final stage is all about our customers. Throughout the display process, various components are tested individually and as subsystems, but the final product is also inspected. OSD Performs 100% inspection on LCD modules including cosmetic, functional, and conformance tests. We maintain a continuous-improvement quality system compatible with our ISO certifications. We additionally are able to cooperate with customers implementing specific test fixtures, or standards, agreed in specification. The completed and tested glass-based product is then focused on protective packaging and preparation for transport globally. Protective packaging can often be custom designed for LCDs and we have packaging design specialists to work with our customers to define this packaging to various levels of requirements . Many items will have customized packaging specifications that can be discussed depending on program requirements. OSD is able to accommodate customer-specified cartons, trays, resale packaging, carton labels with customized inventory management labels, and much more to integrate with the customer's supply chain.