Executive Summary
This white paper provides an overview of the supply chain touchscreen. It will be the main components of the supply chain and touch screen modules available on the market.
Introduction
A detailed understanding of the capacitive touch screen supply chain for the customer, taking into account touchscreen-end products of vital importance. The engagement model should be chosen with the in-house design capabilities, supplierValue Added Services and the available options for module design and supply.
Controller IC Suppliers
The capacitive touch screen controller is a semiconductor device that senses finger position on a touch screen sensor. Different chip architectures and remote sensing methods from different suppliers, which will be used beyond the scope of this document. Capacitive controllers can be divided into two broad categories.
Projected Capacitive
This method senses finger position on aSensor of the electric field projected by a substrate. It is generally implemented with one or more ITO layers structured around one or more transparent substrates applied. Projected capacitive is very durable, because the user the best of the touch of a glass or plastic substrate, while the ITO films are protected below. The coordinates are calculated by measuring signals from patterned ITO to a deterministic position. This makes projecting accurate and repeatable sensing than other capacitivesensing methods. Projected Capacitive controllers usually require more inputs sensing for larger screens. Means, in practice, they are limited in about a 10 "screen size for single-chip solutions. Alternative solutions across multiple controller ICs or unique ITO structure are also possible.
Surface Capacitive
This method uses a single sheet of transparent conductor applied to the sensor substrate, usually ITO on glass, film, or plastic. The method is cost effectiveeffective and suitable for large-volume production with many well-known techniques. Because finger position is determined by four sensors at the corners or edges of the plate may be touch screens, thirty or more inches without increasing the controller IC pin-number scale. There are also considerable disadvantages, especially for smaller screens. First, remote sensing via the touch screen on ITO substrate is carried out. Although the ITO can be protected by a thin hard coating, it is vulnerableto scratch off the fingers, rings, keys, and so on. It is also important inherent nonlinearity of the field for capacitive sensing surface to be corrected if the edge patterns, software or hardware methods. This linearization effect is pronounced with smaller screens. Further details of implementation, such as proximity effect and finger shadow must also be addressed.
Flex Supplier
Flexible Printed Circuit Assemblies (Flex) are used to connect the touch sensor in a systemController board. The flex has assembled an occasional touch-screen controller for supplying a "flex module. Alternatively, a simple circuit flex without controller to the sensor manufacturer, in this case, a controller IC is designed to be delivered to the customer's system" controller board .
Sensor Supplier
Create a rule as a "glass" or "film" suppliers, this member of the supply chain to in-house senior positions on a structuretransparent substrate material. The most common conductor is indium tin oxide (ITO), for the relatively low resistance and high optical clarity. Other transparent conductors in use or under development, but not yet mainstream. Typical sensor substrates are glass, film or polycarbonate derivatives. Some sensor suppliers have additional vertical integration, such as touch-screen controller IC ASIC products, electronics for the controller boards, LCD care, flexFollowing the delivery or the complete module integration.
LCD supplier
Touch screens are typically used in conjunction with video displays, it is logical that LCD manufacturers in the supply chain is essential. Your core is already a participation of deposit patterned ITO on glass and flex circuit for LCD manufacturing. Therefore, it is much easier for them to vertically integrate these important elements of the touch screen supply chain. LCDManufacturers have chosen to simply display to a third party to provide for integration with touch screen modules, or the controller, sensor, glass or flexible printed circuit board in its assembly.
Supply Chain Logistics
Supply chain logistics for the touchscreen production has several permutations, depending on the supplier-customer sales engagement, customer's preferred business model, and the vertical integration of the individual providers. Customers canfirst check, purchase touch screen controllers, sensors, flex and LCD directly from individual suppliers and the performance of their own design and integration. Although these cost savings may have noticed, it is all design, performance and quality issues directly to the customer. Each touch-screen design is unique, so you must configure the controller to correct the sensor characteristics, LCD noise, labor, environment and industrial design factors. This is often outside theAbility of customers for a first draft. The more frequently used approach is for customers to purchase a specially designed and tested good "touch screen module known by one of the participants in the supply chain.
Touch Screen Module
Touch-screen modules are available in three versions depending on the specific retail sale:
Flex Module
This is a combination of controller IC and flexible PCBs. Flex modules are purchased mainly by ITO Sensor SuppliersTouch screen design reduces the cycle time and improve the touch-screen output. The Flex module consists of a flexible circuit board with an attached touch screen controller IC, examined how a known good unit. Flex Modules are usually on ITO Design Controller IC manufacturers or end users through distribution channels. For the Asian market, they are usually "Stocking Reps", which function as a combination of representatives of manufacturers and value-added supply chainManager.
Touch Screen Module
This product combines a Flex module and ITO sensor. With the Flex module, the time to market and improved product reliability, while maintaining flexibility for sensor design. Touch-screen modules are usually from the suppliers of the ITO-glass sensor or film to the big OEM or ODM design retail offer. Some controller IC manufacturers also offer full touch-screen modules for simple construction, though this offer is limited generally to the greatdirect customers. Most large customers have very specific requirements for the marketing industry and product design "look and feel. Subsequently, very few companies an off-the-shelf touch screen module. Most are custom developed directly with the suppliers.
Touch Screen LCD Modules
This is the highest level of integration. It combines a touch screen with an LCD module, create full touch sensitive display device. Design end-user will see the device as a "black box"capable of displaying images and sending touch coordinates to the main system. It is highly desirable for the production of reliability, since each unit of a known good display and touch interface guarantees. Some LCD manufacturers offer this type of module as a product to the general market. For high volume OEM customers, touch-sensor manufacturers and LCDs on the air and produce a touch screen LCD module, glass, Flex and controller IC components.
Abstract
The understanding of the details, such as touch screens are produced to help you choose the right technology and suppliers for your touch-enabled device.
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