Touch screen as an input device with easy to use, durable, fast response time, space-saving and other advantages, the user can use directly through the touch screen to achieve the operation, without the use of a keyboard or mouse, practicality is very strong and widely used.
The quality of the touch screen needs to be verified through testing, in the production of reliability testing must be carried out, the main test items include high and low temperature preservation, cold and hot shock preservation, hitting test, scribing test, surface hardness, surface hydrostatic pressure test, packaging vibration, packaging drop, steel ball impact test and so on. Touch screen test has a greater demand for current transmission, available high-current shrapnel micro-pin module for connection, conduction, first, it can transmit up to 50A current, and can maintain a stable connection; secondly, it will not cause a zap on the connector, with an average of more than 20w times the service life; thirdly, it can cope with the complex test environment, without breaking the pin, not card pin, can effectively improve the test efficiency.
The main components of the touch screen are the sensor unit that handles the user's selection, the controller that senses the touch and locates it, and the software driver that transmits the touch signal to the operating system. These three types of components constitute the working mechanism of the touch screen. In addition to the components, there are several technology types of touch screens: capacitive touch screens, resistive touch screens, infrared touch screens, surface acoustic wave touch screens, and near-field imaging touch screens.
Capacitive touch screen surface coated with a transparent conductive layer ITO, the voltage is connected to the four corners, tiny DC scattered in the screen surface, forming a uniform electric field, the operation of the fun, support for multi-touch, and will not be mistakenly touched. Because it only senses the current of the human body, it can make the corresponding response.
Resistive touch screen is composed of a display and resistive film screen, resistive film screen is divided into two layers, a layer of glass as the base layer, the surface is coated with a transparent conductive layer; outside the base layer is the same conductive layer of plastic layer. Whenever you press or touch the screen, the conductive layer will touch each other to form a contact signal to achieve the operation.
Infrared touch screen is based on the interruption of light technology, set up around the display of an outer frame, the outer frame of one side of the light line or LED, the other side of the light detector or photoelectric sensor, the two sides correspond to the formation of a cross infrared network. Whenever an object is used to touch the display, the infrared rays are blocked, from which the location of the touch point on the screen can be determined.
Acoustic touch screens have sensors mounted on the edge of the glass screen to send ultrasonic signals. Ultrasonic waves are reflected across the screen and accepted by the sensor. Surface acoustic wave signals, is the reflection of the stripe convergence of surface acoustic wave energy into electrical signals; guided acoustic wave technology is the controller through the screen cable to send electrical signals into acoustic wave energy.
Near-field imaging touch screen is composed of two thin glass layer, in the conductive layer to apply the AC signal, the surface of the screen will produce an electric field, when using a finger or conductive pen to contact the sensor, the electric field as soon as a perturbation, the screen will be able to get the signal.
These types of touch screen technology types, resistive touch screen in the work can only judge a control point, more than one will not be able to make a correct judgement, is not suitable for mobile phones with multi-functionality, flat panel, only applies to click, drag and drop, and other simple action judgement. Infrared touch screen resolution is low, the touch mode is more restricted, vulnerable to environmental interference and more sensitive to light environmental factors, these technical limitations make infrared touch screen in the market less popular. Surface acoustic wave screen requires regular maintenance, once the screen surface is stained with dust, oil or liquid, the wave guide slot on the surface of the touch screen will be blocked, so that the wave can not be launched and recognition, resulting in the touch screen can not be used normally.
The capacitive touch screen is very durable, dustproof, waterproof, wear-resistant characteristics, and its multi-touch function can break down the user's touch action, to complete the judgement of complex actions, so it is very ideal for mobile phones, tablet touch screen.