The present application is generally related to MEMS accelerometers and, more particularly, to a MEMS accelerometer package having enhanced resistance to mechanical shock as well as an associated method, apparatus and system.
Accelerometers have become ubiquitous in modern electronic devices. In this regard, the measurement of acceleration along three orthogonal axes can provide for essentially complete characterization of device orientation. An accelerometer that is configured for measuring accelerations along three orthogonal axes in a single, convenient package is often referred to as a triaxial accelerometer.
Many modern electronic systems employ accelerometers for a wide range of purposes. As a general example, the operational state or physical orientation of an associated device can be characterized. As another more device specific example, an accelerometer can be used to detect that a hard disk drive is in a state of free fall such that the read/write heads of the drive can be parked in anticipation of mechanical shock upon impending impact. As still another device specific example, modern cellular smart phones typically include an accelerometer to determine the orientation of the phone for display orientation management and for use by a wide range of applications that can be installed on the smart phone. It is noted that the need for accelerometers suited for consumer-grade electronics such as cellular smart phones has driven the development of MEMS triaxial accelerometers that are typically low-cost.
As still another device specific example, an accelerometer can be used as part of a transmitter that is carried by an inground tool in a horizontal directional drilling system for monitoring the orientation and movement of the inground tool. Such monitoring can facilitate steering as well as monitoring the position of the inground tool. As will be described in detail below, Applicants recognize that the use of consumer-grade low-cost accelerometers in a device that subjects the accelerometer to a mechanical shock and vibration environment can lead to failures of these devices. While the overall failure rate has historically not been high, any premature failure of a transmitter can result in significant problems, including idling a crew and equipment while a new transmitter is obtained, missing deadlines, as well as the cost involved with purchasing a new transmitter. To date, the industry has continued to use these accelerometers for lack of an identified, practical alternative.
The present application brings to light a new approach which provides for the use of low-cost consumer-grade accelerometers in a high mechanical shock and vibration environment in a way which enhances reliability.