Kunlun Tongtai touch screen - the advantages and disadvantages of capacitive touch screen

advantage

1. Durability

The material used in the capacitive sensor interface solution is the same as that of the RTS, which is based on polyethylene terephthalate (PET) with an additional layer of indium tin oxide (ITO). However, capacitive sensors do not have the optical and durability problems of RTS because they are single-laminated and have no air gaps that reduce optical performance, and the former is solid-state with no moving parts, resulting in high reliability and durability.

In capacitive sensors, embedded designers are not limited to bendable surface materials, as capacitance is primarily sensed by non-conductive materials. Even when the sensor is placed under the surface of a durable material such as polycarbonate or acrylic, capacitive sensing is required. In these cases, capacitive sensors still have the environmental durability of a rigid surface, which allows them to operate in environments where other technologies are not adequate. Mechanical simplicity is another major reason for the improved reliability and optical performance. In capacitive sensor modules, the layers are optically matched to each other and laminated together without any air gaps and the internal reflections they cause. Thanks to the extremely thin conductive layer, light absorption is also minimized.

2Support multi-touch

The resistive touch screen can only judge one touch point at a time when working, and if the touch point is more than two, it cannot make a correct judgment, so the resistive touch screen is only suitable for the judgment of some simple actions such as clicking and dragging. The multi-touch of the capacitive touch screen can decompose the user's touch into two tasks: collecting multi-point signals and judging the meaning of the signal, so as to complete the judgment of complex actions. Using two fingers to stretch and transpose on the screen to perform interesting operations such as zooming in and rotating, which was almost univrable before the advent of capacitive touch screens.

3. Stability

Because it is a solid-state sensor, there are no moving parts, and the optical performance remains consistent throughout the sensor's lifetime. Conversely, resistive touchscreens require air gaps and insulation points (spacer dots), both of which produce internal reflections and scattered light. In addition, if the top surface is deformed during resistive touch screen operation, it is necessary to take _f= measures to minimize optical distortion (e.g. Newtonian rings).

Capacitive sensors do not require critical spacing for sensor layers, while bending or deformation of resistive sensors can affect the layer spacing. Capacitive sensors, on the other hand, can sense on curved surfaces with no loss of functionality. In light of these differences, designers can use capacitive sensors to add simple and cost-effective touch sensing when using RTS is effective.

Capacitive sensor-based designs provide excellent optical and finger sensing capabilities to the end user. Due to the optical structure of this sensor, internal reflections are reduced, so that the screen carrying text and graphics is clear and clear.

flaw

As the current popular touch screen technology, although the capacitive touch screen has the advantages of gorgeous interface, multi-touch, and only sensing the human body, at the same time, it also has the following shortcomings:

(1) The accuracy is not high

Since the capacitance value is inversely proportional to the distance between the poles, it is directly proportional to the relative area, and it is also related to the insulation coefficient of the dielectric. Therefore, when the palm of the hand or the conductor held in a larger area is close to the capacitive screen, it can cause the malfunction of the capacitive screen, and in humid weather, this situation is particularly severe, and the malfunction of the capacitive screen can be caused by holding the monitor, the palm of the hand is close to the display within 7 cm or the body is close to the display within 15cm. Since capacitive screens determine their position by sensing an electric current in the human body, they do not respond when touched with a hand that wears an insulating object such as gloves or when holding a non-conductive object.

(2) Prone to drift

When the ambient temperature and humidity change, and the ambient electric field changes, it will cause the drift of the capacitive screen, resulting in inaccuracy. For example, the temperature of the display rises after powering on, which will cause drift: when the user touches the screen, the other hand or side of the body will drift when the user touches the screen; The reason for the drift of the capacitive screen is a congenital deficiency of technology, although the environmental potential surface (including the user's body) is far away from the capacitive touch screen, but it is much larger than the finger area, and they directly affect the determination of the touch position. In addition, theoretically many relationships that should be linear are actually nonlinear, such as: the total amount of current sucked by people with different weights or different degrees of finger wetness is different, and the change of total current and the change of four sub-currents is a non-linear relationship, the custom polar coordinate system of the four corners used by the capacitive touch screen does not have the origin of the coordinates, and the controller can not detect and recover after drifting, and after the completion of 4 A/D, the value of the four shunts is transferred to the x, The process of calculating the Y coordinate value is complex. Since there is no origin, the drift of the capacitive screen is cumulative, and calibration is often required on the job site. The outermost silica protective glass of the capacitive touch screen has good scratch resistance, but it is afraid of the knocking of nails or hard objects, and knocking out a small hole will hurt the interlayer ITO, whether it is to hurt the interlayer ITO or the inner surface ITO layer during installation and transportation, the capacitive screen will not work normally.

The four-layer composite touch screen of capacitive technology has uneven transmittance to each wavelength of light and the reflection of light on each layer, resulting in color distortion and blurred image characters. In addition, there are still certain technical difficulties in the steps of the current capacitive touch screen in the process of attaching the touchpad to the LCD panel, and the yield rate is not high, so the cost of the capacitive touch screen is also increased invisibly.

Kunlun Tongtai touch screen - the advantages and disadvantages of capacitive touch screen

Kunlun Tongtai touch screen - the advantages and disadvantages of capacitive touch screen

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