Sunday, May 28, 2006

US Patent 7049806 - Micromechanical Beam With Resilient Suspension

There are many current commercial applications in divergent fields that employ micromechanical and microelectromechanical systems such as micromirror based displays, microcantilevers for atomic force microscopy, microejectors for inkjet printheads, microsensors, microrelays, etc. Even though micromechanical systems are used in different fields, common problems are found generic to micromechanical structures themselves. This results in inventors focusing on patents for the generic problems of micromechanical structures regardless of the specific application. Unfortunately, the US patent class system does not have a generic class outline for micromechanical systems (although a few areas have been devoted to the fabrication of such systems). This results in a great difficulty for Patent Examiners attempting to search for broadly claimed micromechanical structures. US 7049806 presents an example of such broadly claimed structures. Claim 1 reads:

1. A microelectromechanical system (MEMS) comprising: a beam supported on flexible transverse arms to move longitudinally along a substrate, wherein at least one of the flexible transverse arms is configured to at least one of tolerate and make use of bowing experienced by the arm.

The beam is taught to include structural elements such as serpentine portions allowing for extention and bending of the beam when moving in the direction of extension of the beam. This is taught to compensate for stresses induced by thermal expansion. Unfortunately the Examiner was unaware of earlier patents such as



that would seem to read on some of the claims of US 7049806.

The US patent office has been reluctant to create a patent class devoted to micromechanical systems. Unfortunately this reluctance may result in many micromechanical patents being issued with claims broader than warrented.