From the perspective of technical principles, the touch screen is a transparent absolute coordinate positioning system, first of all, it must be guaranteed to be transparent, so it must solve the transparency problem through material technology, such as digitizers, writing boards, elevator switches, they are not touch screens; Secondly, it is an absolute coordinate, where the finger touches, there is no need for the second action, unlike the mouse, it is a set of systems for relative positioning, we can notice that the touch screen software does not need a cursor, and the cursor affects the user's attention, because the cursor is used for the relatively positioned equipment, and the relatively positioned equipment should first know where it is and which direction to move to a place, and it is necessary to constantly feedback the current position to the user at all times so as not to deviate. None of this is needed for touchscreens that take absolute coordinate positioning; The second is to be able to detect the touch of the finger and determine the position of the finger.
Transparent properties
Transparency, which directly affects the visual effect of the touch screen. Transparency has the problem of the degree of transparency, infrared technology touch screen and surface acoustic wave touch screen are only separated by a layer of pure glass, transparent can be regarded as a leader, other touch screens should be carefully scrutinized, "transparent", in the touch screen industry, is just a very general concept, many touch screens are multi-layer composite films, it is not enough to summarize its visual effect with a little transparency, it should include at least four characteristics: transparency, color distortion, reflectivity and clarity, and can be divided again, For example, the degree of reflection includes the degree of mirror reflection and the degree of diffraction reflection, but the diffraction reflection on the surface of the touch screen has not yet reached the level of the CD disk, and for users, these four measures are basically enough.
Due to the existence of light transmittance and wavelength curves, the image seen through the touch screen inevitably produces color distortion with the original image, the static image feels only the color distortion, and the dynamic multimedia image feels not very comfortable, and the color distortion is the maximum color distortion of the figure, which is naturally as small as possible. The transparency that is usually referred to can only be the average transparency of the graph, of course, the higher the better.
Reflective properties
Reflectivity mainly refers to the light and shadow behind the overlapping image due to specular reflection, such as human figures, windows, lights, etc. Reflective is the negative effect of the touch screen, the smaller the better, it affects the user's browsing speed, and even the image characters cannot be recognized in serious cases, the use environment of the reflective touch screen is limited, and the lighting arrangement on the scene is also forced to need to be adjusted. Most of the touch screens with reflective problems are provided with another model with surface treatment: matte touch screen, also called anti-glare type, the price is slightly higher, the anti-glare type reflectivity is significantly reduced, suitable for very well-lit halls or exhibition venues, however, the light transmittance and clarity of the anti-glare type have also decreased significantly. Clarity, after some touch screens are installed, the handwriting is blurry, the image details are blurry, and the whole screen appears blurry and can't be seen clearly, which is that the clarity is too poor. The problem of clarity is mainly caused by the repeated refraction of light and reflection between the layers of the film, and the anti-glare touch screen also causes a decrease in clarity due to surface frosting. The clarity is not good, the eyes are easy to get tired, and there is also some damage to the eyes.
Absolute coordinates
The touch screen is an absolute coordinate system, and the essential difference between the relative positioning system and the mouse is the intuitiveness in place. The characteristics of the absolute coordinate system are that each positioning coordinate has no relationship with the previous positioning coordinates, the touch screen is physically an independent coordinate positioning system, and the data of each touch is converted to the coordinates on the screen through the calibration data, so that the touch screen is required to have this set of coordinates no matter what the situation, the output data of the same point is stable, if it is unstable, then the touch screen can not guarantee the absolute coordinate positioning, and the point is not accurate, which is the most feared problem of the touch screen: drift. In terms of technical principle, all touch screens that cannot guarantee the same touch at the same point and the same sampling data have the problem of drift, and only capacitive touch screens have drift at present.
Detect positioning
Detect touch and localize, various touch screen technologies rely on their own sensors to work, and some even touch screens are a set of sensors themselves. The respective positioning principle and the respective sensors used determine the response speed, reliability, stability and longevity of the touch screen.