Measuring and testing – Instrument proving or calibrating – Dynamometer
Reexamination Certificate
1998-12-01
2001-01-23
Noori, Max (Department: 2855)
Measuring and testing
Instrument proving or calibrating
Dynamometer
Reexamination Certificate
active
06176117
ABSTRACT:
FIELD OF INVENTION
This invention relates to a calibration instrument for micro-positively-sensed force and calibration method therefor, in particular to a device that utilizes a load cell and a micro-distance meter to measure and to calibrate an apparatus for measuring positively-sensed force of an electrical connector, and to a method for measuring two calibration curves of load of the apparatus vs. strain value, and of displacement vs. strain value. The apparatus for measuring positively-sensed force of an electrical connector is provided with a strain gauge on an elastically deformable sheet, where value of the-positively-sensed force of the connector terminals is obtainable by matching the measured strain value with the two calibration curves.
BACKGROUND OF INVENTION
In engineering an electrical connector, electrical connector terminals must consist of positively-sensed force of a certain amplitude in order to rub off oxides or sulfides of contact surfaces between a circuit board and the terminals thereby attaining acceptable conductive effects, maintaining sufficient contact area between the circuit board and the connector, and preventing fretting corrosion failure as a result of vibration. On the other hand, if other factors, such as wear reduction, spring rigidity and stability, are taken into account in engineering the connector, the positively-sensed clamping force of the electrical connector terminals effecting to the circuit board is preferred to be minimized so as to optimize connector performance. Therefore, how to maintain an appropriate positively-sensed force being effected to the circuit board is an important engineering issue being intensively observed while engineering new electrical connectors or modifying existing electrical connectors. Because amplitude of the positively-sensed clamping force that an electrical connector effects to a circuit board will eventually affect connector reliability and force required for inserting or withdrawing the connector into or from the circuit board, manufactures of electrical connectors have given much consideration to the amplitude of positively-sensed clamping force while engineering electrical connectors. However, apparatus for measuring positively-sensed force of an electrical connector is currently unavailable in the commercial market, where most of the time, connectors are split apart such that positively-sensed force is measured by conducting tensile test thereto. The majority of manufactures also rely on past experiences, repetitive experiments and design modifications to attain the desired positively-sensed clamping force. It is sometimes necessary to rely on the customers to evaluate whether the ultimate positively-sensed clamping force that the electrical connectors effect to the circuit board qualifies the customers' specifications. The only prior art known so far involves U.S. Pat. No. 4,380,171 that was published on Apr. 19, 1983. Hence, manufacturers of electrical connectors in general cost considerable experimental or trial-run expenditures and take an extended engineering term to attain the desired connectors, where such an engineering approach is obviously disadvantageous to the manufacturers in contending orders and in product manufacturing.
Currently, amplitude of the positively-sensed force of an electrical connector is obtained through two schemes, including analysis and experimentation, wherein the method of analysis mostly involves finite element analysis, from which the overall stress distribution and the positively-sensed clamping force of the electrical connector can be calculated. However, since in such a method numeral results are derived from specific mathematical modes, it is essential to select proper modes and to modify the results based on existent conditions in order to attain correct values. Thus, implementation of the method of analysis still relies on actual measurements of the positively-sensed force to verify the results of the finite elements analysis, to serve as a reference for modifying the analysis modes, and to help engineers who design the electrical connector to acquire feeling for the amplitude of the positively-sensed force. Therefore, taking actual measurements of the positive force is an extremely vital technique in engineering electrical connectors.
In addition, recent development of electronic industry has gradually reduced thickness of common circuit boards down to approximately 1 mm, or even thinner; compact and high density designs are thus trends that electrical connectors must follow, which trends eventually result in reduction of terminal volume and intensify difficulty for measuring the positively-sensed force of such miniature products. Most researches related to taking actual measurements of positively-sensed force of electrical connector terminals being conducted by research teams, are still in the conception stage. It is to the applicant's knowledge that commercial products that are equipped with such functions are currently unavailable in the market.
SUMMARY OF INVENTION AND RELEVANT PRIOR ART
It is a primary object of this invention to provide a device and a method for calibrating an apparatus for measuring positively-sensed force of an electrical connector, which is disclosed in a co-pening patent application entitled “Apparatus for Measuring Positively-sensed Force of an Electrical Connector” filed by the same Applicant, such that manufacturers of electrical connector may conveniently, and easily measure the positively-sensed clamping force of their connector products effecting to circuit boards. It is worthy to note that, though in the preferred embodiments as discussed in this invention, the device being calibrated is an apparatus for measuring positively-sensed force of an electrical connector, this invention is not limited to such a calibration application. In other words, this invention may also be used as a calibration device or method for calibrating other apparatus.
This invention is primarily related to a calibration instrument for micro-positively-sensed force and calibration method therefor, where the instrument is implemented in an apparatus for measuring positively-sensed force of an electrical connector to measure a calibration curve of load (positively-sensed force) vs. strain value and a calibration curve of displacement vs. strain value, such that upon insertion of this invention into the electrical connector, value of the positively-sensed force is obtainable by matching the strain value displayed in a signal amplifying device with the two calibration curves. Detailed structure and features of such an apparatus for measuring positively-sensed force of an electrical connector are disclosed in a co-pening patent application entitled “Apparatus for Measuring Positively-sensed Force of an Electrical Connector” filed by the same Applicant.
The structure and advantages of this invention may be clearly understood by referring to the following illustrations and descriptions of preferred embodiments.
REFERENCES:
patent: 3956919 (1976-05-01), Vranas
patent: 4380171 (1983-04-01), Smith
patent: 5020357 (1991-06-01), Kovacevic et al.
patent: 5092154 (1992-03-01), Eldridge et al.
patent: 5355715 (1994-10-01), Rausche et al.
patent: 5501096 (1996-03-01), Stettner et al.
Chen Li-Sen
Jao Wei-Tai
Wu Chih-Ming
Yen Hung-Ju
Industrial Technology Research Institute
Merchant & Gould P.C.
Noori Max
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