Measuring and testing – By abrasion – milling – rubbing – or scuffing
Reexamination Certificate
1999-11-22
2001-07-10
Noori, Max (Department: 2855)
Measuring and testing
By abrasion, milling, rubbing, or scuffing
Reexamination Certificate
active
06257046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and apparatus for determining the electrostatic force present in an object, more particularly to a method and apparatus in which the electrostatic force is determined in terms of the weight of standardized testing membranes.
2. Description of the Related Art
Fibrous materials, such as non-woven fabrics, used as filter media in air filters, respirators or the like are electrostatically charged for efficient collection of dusts and other microparticles. The dust collecting properties of such a filter medium depends on the sufficiency of the electrostatic force present therein. Electrostatic force is however unfavorable for fibrous materials which are used as absorbent materials in diapers, feminine hygiene products, etc., and should be removed or reduced to a minimum. It is therefore important for manufacturers to evaluate or inspect the level of electrostatic force present in such fibrous materials in order to ensure good quality of their products.
Generally, expensive electrical instruments are used in conventional methods of measuring electrostatic forces. In an example of these methods, a capacitor-type probe is used as a detector for detecting electrostatic charges, and the detected signals are converted and amplified via additional electronic parts. While the instrument used in this method is sensitive and can provide accurate results, the construction thereof is complicated and the results thereof can be readily influenced by the surrounding conditions, such as the temperature, humidity, and the distance between the probe and the article to be tested. It is not economical to use such an instrument for testing and inspecting the electrostatic forces of products which are mass-produced and which do not require accuracy.
SUMMARY OF THE INVENTION
An object of the present invention is to provide simple and inexpensive method and apparatus for determining an electrostatic force present in an article.
Another object of the present invention is to provide an approximate evaluation method which is however reliable for determining an electrostatic force present in an object.
According to one aspect of the present invention, a method for determining an electrostatic force present in a flat object such as a fabric, includes: (a) positioning the object on a flat support; (b) providing a series of testing membranes which are substantially free of electrostatic charges and have different standarized weights; (c) placing on the surface of the object one of the testing membranes and turning the support to an inclined position relative to a horizontal plane; (d) repeating step (c) with the other ones of the testing membranes; (e) examining which one of the testing membranes slides relative to the object after the support is inclined, and determining the smallest weight among the standarized weights, that permits a sliding movement between the testing membranes and the object, and the largest weight among the standarized weights, that prevents the sliding movement; and (f) evaluating the electrostatic force as a function of the largest weight and the smallest weight.
According to another aspect of the invention, an apparatus for determining an electrostatic force present in a flat object, comprises a turnable support having a flat face and a positioning means adapted to position the object on the support, and a series of testing membranes adapted to be placed on the surface of the object held on the support, the testing membranes being substantially free of electrostatic charges and having different standarized weights.
According to still another aspect of the present invention, a method for determining an electrostatic force present in a fabric, comprises: a) positioning the fabric on a flat support; (b) placing on the surface of the fabric a testing membrane which is substantially free of electrostatic charges and which has a standarized weight; (c) turning gradually the support to an inclined position relative to a horizontal plane; (d) measuring the angle of inclination of the support which causes the testing membrane to start to slide downward relative to the fabric; and (e) evaluating the electrostatic force as a function of the weight of the testing membrane and the angle of inclination.
REFERENCES:
patent: 3828250 (1974-08-01), Buser et al.
patent: 3835380 (1974-09-01), Webb
patent: 3898001 (1975-08-01), Hardenbrook et al.
patent: 4983923 (1991-01-01), Taniguchi
patent: 5682102 (1997-10-01), Takahashi et al.
Chu Wei-Cheng
Huang Yii Feng
Teng Kun-Sheng
Wang Yu-Fen
Dickinson Wright PLLC
Kang Na Hsiung Enterprise Co., Ltd.
Noori Max
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