What is a touch panel?
The touch panel is also called Touch Panel, or Touch Screen, or Touch Pad, etc.. All electronic devices use the screen. If you don't want your screen to be occupied by a boring keyboard, you must use the touch screen. As the medium of human-machine dialogue, touch screen is the latest computer input device. It is the simplest, convenient and natural human-computer interaction method. It gives multimedia a new look and is an attractive new multimedia interactive device.
The touch panel was first introduced in 1965 by EA Johnson, a short article describing capacitive touch screens, and then in 1967, there was an article with a truth in the picture. In 1970, two transparent engineers from the two CERN (European Council for Nuclear Research) inventors invented the transparent touch panel in the early 1970s and put it into use in 1973. Then in 1975, an American George Samuel Hurst invented the resistive touch panel and obtained the US patent (#3, 911, 215), and commercialized in 1982.
1. Technical points of the touch panel:
From the technical point of view, the touch screen is a transparent absolute positioning system. First, it must be transparent. Secondly, it is absolute coordinates. Where is the finger touch? It is not like the mouse needs a cursor for relative positioning, so it is very It's easy to distract, because you have to pay attention to where the cursor is.
The structure is usually covered on a semi-reflective liquid crystal panel (ITO transparent conductive electrode), which is highly sensitive to pressure. When an object is pressed on it, a current signal is generated and a pressure source is determined. Location and dynamic tracking. This is the on-cell technology that we report in the media. Now, the In cell Touch touch component is integrated into the display panel, so that the panel itself has a touch function, and the touch effect and application can be achieved without the need for additional bonding and assembly with the touch panel, mainly Apple is researching.
Next, we mainly introduce the differences and principles of different touch technologies from transparency and positioning methods.
2. Classification and principle of touch panel:
From the technical principle to distinguish the touch screen, it can be divided into five basic categories: vector pressure sensing technology touch screen, resistance technology touch screen, capacitive technology touch screen, infrared technology touch screen, surface acoustic wave technology touch screen. Among them, the vector pressure sensing technology touch screen has withdrawn from the historical stage; the infrared technology touch screen is inexpensive, but its frame is fragile, easy to produce light interference, and the surface is distorted; the surface acoustic wave touch screen almost solves all kinds of defects of the touch screen, clear and not It is easy to be damaged and suitable for various occasions. The fatal disadvantage is that if there are water droplets and dust on the surface of the screen, the touch screen will become dull or even not working, so it is difficult to popularize. The following mainly talk about resistive and capacitive screens.
Resistive: It's good to use!
The resistive touch panel is mainly composed of two film substrates coated with ITO (indium tin oxide) on one side, and the upper and lower plates need to be filled with transparent elastic spacers to separate them. It is shown that the lower plate must be a rigid thick glass to prevent deformation, while the upper plate needs to induce an external force to deform, so that it is necessary to explode glass or plastic.
During normal operation, the upper and lower plates are connected to the voltage and are in the off state. When the external force is pressed, the upper plate is deformed and the lower plate is in contact with the lower plate. At this time, a voltage change is generated, and the touch point coordinates can be accurately measured by the voltage change ( Because the upper and lower plates are touched by the upper and lower plates, the upper and lower plates are changed into a resistor divided into two, and the value of the resistance value is proportional to its distance from the edge to calculate the X and Y coordinates. Therefore, the accuracy of the resistive touch screen mainly depends on the conversion accuracy of this coordinate voltage, so it is very dependent on the accuracy of the A/D converter (voltage sensitivity of the magnitude).
Because the resistive screen is controlled by pressure, it does not have to be controlled by hand. The pen, credit card, etc. can be operated. Even if it is worn, it does not matter, and it is isolated from the outside world, so it has the advantage of dustproof and antifouling; If the "touch" is too light, the resistive screen will not respond, so you should use a light stamp. The resistive screen has low cost and low technical threshold. Moreover, it needs to be tapped when operating the resistive touch screen, so it is easy to be bad, and the sensitivity is not so good, and the drawing and writing are not smooth.
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