Application of spectral confocal technology in high-precision measurement of transparent components of mobile phones

With the rapid update of 3C product exterior design and continuous upgrading of material technology, the demand for precision measurement technology in the manufacturing process of 3C products has become increasingly high in recent years, especially for precision measurement needs such as 3D curved screens and mobile phone cameras.

Spectral confocal sensors, as a high-precision measurement technology with wide adaptability to the environment and materials, are increasingly favored by precision manufacturing industries such as 3C due to their obvious advantages such as high speed, high accuracy, and high adaptability. In this issue, we will share several cases of spectral confocal detection in transparent workpieces of mobile phones.

In recent years, almost all flagship phones of brands have been equipped with curved screens. Curved screens have been popular among global consumers due to their three-dimensional display and excellent touch feel, and have become the mainstream of product lines for major consumer electronics manufacturers. However, curved screens have also brought new challenges to mobile phone appearance inspection.

In the hot bending process of 3D curved glass, due to issues such as graphite mold design and temperature control during the pressing process, 3D curved glass may have poor "warping" or warping issues. This will greatly affect the efficiency of the surface fitting process in the future. If it cannot be fully fitted, there may be touch issues with the 3D screen. Therefore, it is necessary to measure the contour of 3D curved glass to ensure that the actual contour line is within the tolerance zone.

Difficulties in detection

1. The reflective glass surface is smooth and reflective strongly. If laser triangulation and structured light measurement methods are used, the diffuse reflection signal of reflective surface will cause serious interference to the measurement signal, and the measurement data accuracy is poor. The spectral confocal measurement technology utilizes surface reflection for measurement, which is suitable for measurement tasks on glass surfaces.

2. Large angle curved glass and lenses with large angle curved surfaces require spectral confocal sensors to have a large measurable inclination angle. Due to the limitations of its optical system design, spectral confocal sensors cannot have both a large measurable tilt angle and a large range. Therefore, in order to measure curved surfaces with large angles, it is necessary to use a spectral confocal sensor to build a measurement module.

3. Online measurement. To control the yield rate, online measurement is required. The online measurement time for multiple items such as length, width, height, R-angle, and profile of a single 3D curved glass is 3-10 seconds, which puts forward high requirements for the efficiency of the measurement system. In addition, online measurement also requires extremely high system stability to avoid downtime affecting normal production.