Vehicle air conditioner controllers mostly use traditional physical and mechanical keys. This paper mainly discusses the application of capacitive touch keys, another new type of keys, including the comparison of the advantages of touch keys and traditional keys, and introduces the structure and design considerations of capacitive touch keys, which can give follow-up capacitive touch keys. The structure design provides a reference.
With the popularity of various capacitive touch electronic products, touch products bring convenience, technology and fashion to end users. With the popularity of automobiles in people’s lives more and more widely, automotive interior decoration is bound to receive consumer attention.
As an indispensable automotive parts in the car, air-conditioning controller, the sense of technology, convenience and convenience of products will become a very important factor affecting automotive sales.
The key panel style products of air-conditioning controller largely determine consumers’recognition of the products. In automobile air-conditioning controller products, the common keys are basically traditional physical keys, that is, they need to press the keys to move up and down to achieve the action of on and off, thus triggering the corresponding function operation of the air-conditioning controller. It is not difficult to find that touch keys will become the main direction of the next generation. Touch keys will be favored by more and more end consumers because of their sensitivity, ease of operation, strong sense of science and technology and strong sense of fashion.
This paper mainly introduces the structure of capacitive touch button and the matters needing attention in its structure design. Because of the use of non-mechanical contact switch, no mechanical action parts, the panel can be made into a sealed type, which can effectively waterproof, dust-proof, oil-proof, anti-static interference. Traditional physical keys: It is easy to weaken the force, function failure, wear and tear the surface, dust entry, and complicated structure design. Advantages of touch keys: dustproof, waterproof, no life limit, simple design showing grade, highlighting the sense of science and technology, leading the trend. Structural film: Substrate of touch film.
ITO and PEDOT: ITO is mainly used to make liquid crystal display, flat panel display, plasma display, touch screen, electronic paper, organic light-emitting diode, as well as solar cells, antistatic coating and EMI shielding transparent conductive coating; PEDOT is a polymer.
PEDOT is widely used in organic thin film solar cell materials, OLED materials, electrochromic materials, transparent electrode materials and other fields because of its simple molecular structure, small energy gap and high conductivity.
There are two schemes for conductive polymers commonly used in thin film keys, thermostatic element ITO and PEDT.
Our current suppliers have both schemes. From the point of view of the process, ITO scheme belongs to the subtraction process, that is, the whole piece of film has ITO material in the process of making, which etches the part that does not need conduction, and retains the part that needs conduction. On the contrary, PEDOT scheme is an additive process, that is, the conductive part is needed to print, and the conductive part is not needed to print. In practical application, due to the characteristics of ITO and PEDOT materials, ITO is brittle and PEDO is flexible. It is suggested that the PEDOT scheme be adopted for vehicle-mounted products. ITO also has vehicle-mounted schemes. From the perspective of industry information, the follow-up PEDOT will become the mainstream based on cost and process. The sensing area of human fingers and keys is equivalent to the positive and negative poles of parallel capacitors. When human fingers are close to the sensing area of keys, the distance between the positive and negative poles of capacitors changes, resulting in the capacitance change. When the touch chip detects the capacitance rise, it outputs switching signals. The basic principle of capacitive touch induction button is a capacitor that continuously charges and discharges. This capacitor has a fixed capacitance value, a fixed charge and discharge parameters, and the capacitance value and frequency can be measured. If you touch the button with your finger or stylus, the capacitance of the button will be changed, and the charging and discharging cycle will be changed.
The touch button chip can detect and detect the touch action. Previous customers should avoid Y-type or T-type layout when giving suggestions on style diagram. Y-type or T-type layout should be considered from the utilization rate of jigsaw.
If you want to design a Y or T style, you need to take full account of the utilization rate of the jigsaw to achieve the optimal scheme.
The above is the schematic change. The shape of the key is very important to the performance of the key. The following shapes are recommended: circular, circular, square and rectangle; triangular or abnormal shape should be avoided as far as possible; and because the sharp angle will concentrate the magnetic field, the sharp angle less than 90 degrees should be avoided as far as possible in the design. With the rapid development of automobile industry, capacitive touch keys will become an inevitable direction for subsequent air-conditioning instruments. For the structure application design of capacitive touch keys, we must focus on the following two aspects: (1) the structure composition of capacitive touch keys; (2) the key points for the structure design of capacitive touch keys.