Touch Screen

The touch screen is introduced

Also called a touch screen, only one control skills, divided into two ( capacitance, resistance screen ).

Touch screen based on the medium as well as the working principle, can be divided into resistive, capacitive induction, infrared type and surface acoustic wave type four. Touch screen from low-grade to high-grade gradually upgrade and development: from the resistance type, infrared type to capacitor induction type and surface acoustic wave.

Multi touch technology

Touch technology we are not unfamiliar, already had. Bank teller machine is mostly a touch screen, a lot of hospital, library, hall has the touch technology computer. Support touch screen mobile phone, MP3, digital cameras are also many. Touch technology, with fingers instead of the keyboard and mouse, which display in addition to the maximum of humanity, and in certain situations reducing the mouse and keyboard. But these already existing touch screen is a single touch, also can saying is resistive touch. His main drawback is the only recognition and support each time a finger touch, click.

This year, Microsoft in talking about multi-touch applications, the upcoming release of the Windows 7 ( Vista upgrade product) will fully support multi-touch technology. Multi touch technology is a touch technology revolution, that is the screen will be able to identify your five finger while doing the click, the touch-control action. We know that a finger can only do the action of a click, but five fingers derived action will be a lot of very rich. Unfortunately there is no see this multitouch computers, HP is said to do a can support two finger movements of the touch screen.

Why is iPhone so hot, the key is its multi-touch screen technology, the other mobile phone manufacturer is deadly. The company has for the multi touch technology applied for two patents.

Multi touch technology and is not easy to achieve, it is from hardware to software of an organic whole, can saying is a system engineering.

Capacitive touch screen

Capacitor type touch screen using the human body sensing of the current work. Capacitive touch screen is a piece of four layer composite glass screen, glass screen and the inner surface of the interlayer is coated with a layer of ITO ( conductive glass coating ), the outer layer is a thin layer of silica glass protection layer ITO coating is used as a working surface, a four angle from four electrodes, inner ITO is a shielding layer in guarantee a good working environment. When a finger touches the metal layer, the body electric, the user and the touch screen surface to form a coupling capacitor for high frequency current, capacitance is direct conductor, then from the point of contact fingers from a very small current. The current from the touch screen on the four corners of the electrode outflow, and flows through the four electrode current and the finger to the four angle is proportional to the distance, the controller based on the four current ratio calculation, the touch point position information.

Capacitor type touch-control screen advantages

And resistance type touch screen and electromagnetic induction board compared to a capacitive touch screen showed better performance. Because touch feel, easy to use. And the fingers and touch screen contact with almost no wear, stable performance, via mechanical testing the service life of 30 years. In addition, the product is mainly composed of a only a high-integration chip PCB structure, less components, good product consistency, high rate of finished products.

Capacitive touch screen.

On behalf of the popular leader iPhone using a capacitive touch screen will undoubtedly further prove its have various advantages. However, xiabuyanyu, capacitive touch screen is also facing the following challenge: because the body become a circuit part, so the drift phenomenon more serious ; capacitive sensing input technology in small and medium size flat panel display input or control point target (such as a soft keyboard on the phone number or the input word ) when the application needs to be improvement; temperature and humidity drastic changes performance not stable enough to be calibrated frequently ; not applicable to metal cabinet ; when the external inductance and magnetic induction time, may make the touch screen to malfunction. Although available pen tool instead of a finger touch, but its price is more expensive.

Resistance type touch screen

Resistive touch screen ( Touch panel of resistance) also known as resistive touch panel, is a can receiving contact input signal induction type liquid crystal display device, when contact is made with the graphics on the screen button, the screen of a tactile feedback system can be based on pre-programmed program drive link device, can be used to replace a mechanical type the button panel, and by the liquid crystal display screen manufacturing vivid video and audio effect.

As they are a kind of completely isolated from the outside world working environment, no dust, water and oil

It can use any object to touch, can be used for writing and drawing, this is their comparative advantage

The resistive touch screen accuracy depends only on the A / D conversion accuracy, it can easily achieve 4096 * 4096, compared to five line resistance than four wires to ensure resolution accuracy but also is superior, but the cost is large, so the price is very high.

1, four wire resistive touchscreen

Four wire resistance analog technology of two layers of transparent metallic layer each layer were increased when 5V constant voltage : a vertical direction and a horizontal direction. A total of four cables. Features: high resolution, high speed transmission response. The hardness of the surface treatment, reduce abrasion, scratch and chemical processing. With the glossy and matte deal. A correction, high stability, and never drift.

2, five wire resistive touchscreen

Five wires resistive touch screen technology base to two directions of the voltage field via a precision resistor network are added in the glass conductive surface, we can be simply understood as two orientations of the voltage field work time and in the same plane, while the outer layer of nickel metal conductive layer only used as pure conductor there is touch, time-sharing detecting inner ITO contact points X and Y axis voltage value is measured by means of the position of the touch point. Five wire resistive touch screen inner ITO four lead wires, outer conductor just only a touch screen to lead a total of 5. Features: high resolution, high speed transmission response. High surface hardness, reduce abrasion, scratch and chemical processing. With the point of contact of 30000000 can be used. Conductive glass substrate of the medium. A correction, high stability, and never drift. Five wire resistive touch screen with high price and high demand for environment.

3, resistive screen limitations

Whether four or five wire resistive touch screen wire resistive touch screen, which is a kind of completely isolated from the outside world working environment, not afraid of dust and water vapor, it can use any object to touch, and can be used to write and paint, more suitable for the field of industrial control and office limited use. Resistive touch screen common shortcoming because composite film outer layer is made of plastic materials, people who do not know too much force or use sharps touch may scratch the touch screen and scrapped as a result. However, at the limit, scratches will only hurt the outer conductive layer, the outer conductive layer scratch for five wire resistive touch screen, it doesn't matter, and on four wires resistive touch screen is fatal.