Development And Research Of The Control System Of The Mobile Phone Touch Screen Tester

With the improvement of people’s living standards and the rapid development of technology, the intelligent mobile phone is more popular among consumers, and the touch screen is an essential part of it. The resolution of touch screen and the sensitivity of touch are important indicators which are people concerned. Therefore, the test for touch screen parameters on mobile phones becomes particularly vital before they are delivered into markets. However, the difficult of the detection is how to control the force which the mechanical arm exert on the touch screen, and how the mechanical arm accurate positions to the touch screen mobile phone. This article are studied according to these two points:1. The system based on vision alignment positioning of the Blob principle was designed, and the system with optical fiber sensor for reference was measured around the scanning head for optical fiber sensor. The coordinate of the center of the head facing the optical fiber sensor was measured by least squares fitting, then the camera scanned optical fiber sensor. The coordinate of the center facing to the camera optical fiber sensor was drew with the Blob analysis principle, then the relationship between the probe coordinate system and camera coordinate system were calculated by conversion relationship between coordinates, which can draw the coordinates facing to the camera phone touch screen.2. The design of the mechanical arm of the probe is the core part of the test instrument. The force way of the voice coil motor changed the traditional force way of low-friction cylinder, and the closed loop negative feedback was designed to improve test Accuracy. The minimum equivalent step of Z axis achieved 0.01 mm.Before the tester used formally, a lot of experiments were carried out, and the repeated positioning accuracy could achieve ? 0.01 mm in the vision alignment system during every test. This means that the test device could meet the test requirement.At present, the tester has been accepted by customers and operate stably.