China's automobile industry has made great progress in R&D and product quality after nearly three decades of development. With the improvement of automobile intelligence and electrification level, more and more controllers are applied in the whole vehicle, and the switch as a manipulator is getting more and more streamlined. This paper describes the current research status of automotive switches and the future development trend of soft and hard switches.

Switch classification

Vehicle switch according to the location and functional requirements in the car is divided into four categories of switches, respectively, the steering column switch assembly, door guard switch assembly, instrument panel switch assembly, contact switch assembly.

Switch structure form

Switches are divided into the following categories according to their structure: push type, rotary type, and touch type.

Push type switches include Push switches, Push switches with self-locking, Rocker switches, Push-Pull switches, and so on. Push switch is the most widely used type of switch, which is mainly composed of key cap, shell, conductive rubber board, PCBA, bottom cover, key cap and bottom cover are installed on the shell through the buckle, as shown in Figure 1.

1-Key cap 2-Case 3-Conductive rubber 4-PCBA 5-Bottom cover 3.1-Contacts 4.1-LEDs

Rotary types include combination switches, air conditioning control knobs, volume adjustment knobs, etc. The combination switch is a very highly integrated switch, for example, the wiper handle integrates all the functions of wiper and washer, in which the intermittent wiper frequency control of the front wipers and the rear wiper wiper mode control are realized by rotary operation, as shown in the figure. As the internal space of the combination switch is very narrow and the structure is very complicated, thus it is not possible to set the background light and working indicator, and its handle is mostly made of nylon material, and the icon is sprayed and printed on the surface of the handle.

Combination Switch Handle

The volume adjustment knob is a typical rotary switch that is used in a wide variety of applications. The structure is shown in Fig. 3. The knob drives the rotary encoder to rotate infinitely, and outputs a rectangular wave to the multimedia controller through PCB to adjust the volume up and down; the button can trigger the micro switch to turn on the mute function when it is pressed. The buttons are made of PC material, with painted end caps and laser-engraved icons, and the background light LEDs are pasted in the circuit board directly under the icons, which are controlled by the BCM to light up.

3 Rotary switch structure

1-Button 2-Knob 3-Housing 4-Rotary encoder 5-PCB 5.1-Microswitch 6-Base

The touch type includes instrument panel center switch group, center console switch group and so on. Touch switches often use the IML process to inlay capacitive film and printed circuits in the panel, which not only has the aesthetics and environmental protection of the in-mold decoration process, but also realizes the seamless combination of function and structural decoration in one piece molding.

Touch switch

Automotive switch as a variety of controller controls, responsible for the vehicle more than 60% of the function of opening and closing, the existing development trend to cancel the original many physical keys, integrated in the control screen to do soft switch, both can reduce the cost and meet the overall interior reflect concise and intelligent.