1、Concept

Conventional types of keyboard include mechanical button and capacitive button. There is also a kind of keyboard with light-touch membrane button among industrial personal computer keyboards. Mechanical keyboard is a structure which has been applied at the earliest, with the principal similar to touch switches where contactors are connected or disconnected, which features in simple process, repair convenience, ordinary hand feeling, large noise and easily wearing. Most cheap mechanical keyboards use copper springs as elastic materials, and copper will be easily folded and easily lose elasticity. Therefore, the fault rate will increase after a long term of use. Capacitive keyboard is designed based on capacitive switch, which changes inter-electrode distance to change capacitance and obtains temporary conditions for vibration pulse to pass. Theoretically, such switch is of noncontact type, and wear rate is extremely small and can even be neglected. It has no risk of poor contact, and features in small noise and being easy to control hand feeling, which can be used to produce high-quality keyboard, but has more complicated process than mechanical structures. There is also a kind of keyboard used in industrial personal computer, which applies light-touch membrane buttons for full sealing, and is only suitable for special occasions.

2、Measuring Element

Keyboard enclosure dimension, positioning of keyboard circuit board, hole site and appearance of keyboard insulating film

3、Difficulty

Keyboard is the most common and uppermost input device, which has a huge market demand. Among the electronic consumer goods, generally, keyboard is a large-sized auxiliary device, and its frame and membrane materials are electronic parts of larger size due to their overall assembly. Large-stroke instrument is needed during testing for matching. Meanwhile, large-stroke measurement instrument always has lower measurement efficiency, especially for measurement of multiple dimensions of complicated structures such as keyboard.

4、Solution

VMQ mobile-platform image measuring instrument is an original high-efficiency and non-contact measuring instrument in this field, which integrates high coverage, extended depth of field and long stroke, and has improved measurement efficiency by more than 10 times. It is designed with the function of coordinate registration, which can automatically match work pieces and achieve automatic positioning. Within its large coverage range, number of measured elements is not limited, all can be measured and several keyboard jigsaws can be completed within 1 second at a super high efficiency.