Watch maker Citizen to mass produce CMOS camera modules with auto focus function for cellular phones

21 May '05

6 min read

Use of a CMOS sensor has helped to achieve a drastic cost reduction over the CCD sensor.

The use of Citizen Electronics Co.'s unique collective process (*1) in the manufacture of this product has made it possible to lower production costs.

1. The collective process is the basic method employed to produce electronic parts at Citizen Electronics Co. Multiple products are fabricated on a single substrate, which is finally cut into different products. This method has been adopted in the production of a large variety of items, including chip LEDs, switches, photo-sensors, and condenser microphones. Applied to the manufacture of large quantities of different products, the method has reduced production costs and improved uniformity of quality. It permits ease of design change and is also suited to the limited production of a variety of products.

The new material resin (*2), which uses carbon nanofibers jointly developed by Miyota Co. and Shinshu University, is used in the lens holder. As a result, high image precision and a high yield have been achieved (*3).

2. A composite material produced by mixing polybutylene terephthalate (PBT) and carbon nanofibers named VGCF (vapor-grown carbon fiber, a multi-layered carbon nanofiber developed by vapor deposition) at a certain ratio. Originated by Professor Morinobu Endo at Shinshu University, it is attracting attention as ENDO FIBERS.

3. For a small camera module to reproduce a mall camera module to reproduce a fine image, it must have a lens holder (optical tube) of a high precision capable of correctly maintaining the relative positions of the various lenses. Development of a high-precision lens holder, therefore, is a major challenge in the improvement of image quality and yield. The new lens holder made of the new material surpasses its conventional counterpart in fluidity and thermal conductivity, is less likely to produce an error in injection molding, offers higher image quality (up 20-30% in the center area and double the quality in the peripheral area), and features a high yield.

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