Paper making and fiber liberation – Processes and products – Article forming processes
Reexamination Certificate
2002-03-29
2004-05-25
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Processes and products
Article forming processes
C162S181100, C162S181400, C162S181600, C162S228000, C181S167000, C181S169000, C381S426000, C381S428000
Reexamination Certificate
active
06740202
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a speaker diaphragm and a method of manufacturing the speaker diaphragm.
The present application claims priority from Japanese Application No. 2001-103117, the disclosure of which is incorporated herein by reference for all purposes.
2. Description of the Related Art
Conventionally, as the base materials for forming speaker diaphragms, flammable materials, such as paper, a variety of resins, fabrics or the like, are typically employed because of their lightweight properties and low cost.
Accordingly, when an abnormal current flows through the speaker or when abnormal heating occurs on the periphery of the speaker, there may be cases where an accidental fire originates in the diaphragm, which has the largest area among the parts making up the speaker, and spreads.
Paper, woven fabric and non-woven fabric are most commonly used due to they having the lightest weight and the lowest cost among conventional materials for diaphragms, but they typically are so high in hygroscopicity or water-absorption properties that after the paper, woven fabrics or non-woven fabrics absorbs moisture or water, the binding between fibers making up the material decrease, resulting in a decrease in strength of the material.
Therefore, a problem is that the paper, woven fabric and non-woven fabric are unfit for diaphragms of speakers placed in harsh use-environments where water is directly poured on it or in humid surroundings, e.g., a vehicle-mounted speaker.
Moreover, in order to enhance extension of a high-pitched tone in the speaker, the speaker needs a hard and lightweight diaphragm.
With the conventional diaphragms using paper, the diaphragm is made to be hard by mixing a paper pulp with fibers, such as carbon fiber, or an inorganic substance, such as mica, as a filler in making paper or by impregnating paper with resin.
However, though mixing the paper pulp with the filler or impregnating paper with resin can provide a hard diaphragm to a certain extent, this has not been able to provide a diaphragm satisfying the requirements for a tweeter serving as a speaker designed specially for high frequency.
As the diaphragms for the tweeter, conventionally, a variety of materials are used: for example, metal such as aluminium, beryllium and titanium, a resin film made of polyimide or the like, and carbon.
However, there is a problem that the metal is heavy in weight and the resin film made of polyimide or the like, and carbon are high in cost.
SUMMARY OF THE INVENTION
The present invention has been made to solve the problems associated with the conventional speaker diaphragms as described above.
It is therefore a first object of the present invention to provide a speaker diaphragm having water resistance and humidity resistance without the possibility of an accidental fire, and having a high rigidity with light weight.
Further, it is a second object of the present invention to provide a method of manufacturing a speaker diaphragm allowing the attainment of the first object.
To attain the first object, a speaker diaphragm according to a first aspect of the present invention has the feature of including a material resulting from combining a ceramic-type-coating agent with a fiber-type material.
The speaker diaphragm according to the first aspect is formed by various methods; for example, the fiber-type material is formed into an arbitrary shape of the diaphragm, and then combined with the ceramic-type-coating agent through impregnation or coating; the ceramic-type-coating agent is mixed into the beaten fiber-type material and then processed into paper to form an arbitrary shape of the diaphragm; the fiber-type material is impregnated or coated with the ceramic-type-coating agent, then beaten, and then processed into paper to form an arbitrary shape of the diaphragm.
According to the first aspect, the covering of the surface of the fiber-type material, which is a base material of the speaker diaphragm, with a ceramic film causes the speaker diaphragm to be incombustible or flame-retardant. This prevents the speaker from bursting into flames as a result of the diaphragm catching fire.
Further, the ceramic film formed by the ceramic-type-coating agent having been combined with the fiber-type material increases the rigidity of the diaphragm. Hence, it is possible to significantly improve the endurance against impact even when the diaphragm is placed in a vehicle-mounted speaker, for example.
Still further, the ceramic film formed by the ceramic-type-coating agent having been combined with the fiber-type material improves humidity resistance and water resistance and strengthens the binding between the fibers. Hence, the environmental resistance including thermal resistance is improved to allow the diaphragm to be used in speakers which are placed in harsh environments where water is directly poured on it or the temperature and humidity are high, as in the case of a vehicle-mounted speaker, for example.
Further, according to the first aspect, the impregnation or coating of a fiber-type material, such as paper pulp, or a cloth material, such as glass cloth, with the ceramic-type-coating agent allows the provision of the lightweight and high-rigid diaphragm at low cost.
The use of ceramic for the diaphragm allows a significant extension of the high frequency characteristics of the speaker.
To attain the first object, a speaker diaphragm according to a second aspect of the present invention has the feature, in addition to the configuration of the first aspect, that the ceramic-type-coating agent is a ceramic-type-coating agent made up of at least one item selected from the group consisting of an alkoxy metal, a hydrolysate of the alkoxy metal and a partial condensation product of the hydrolysate.
With the speaker diaphragm according to the second aspect, after the ceramic-type-coating agent made up of at least one item selected from the group consisting of an alkoxy metal, a hydrolysate of the alkoxy metal and a partial condensation product of the hydrolysate, is applied to the fiber-type material such as paper or resin, the ceramic-type-coating agent is hardened at room temperatures or by low-temperature heating, and undergoes hydrolysis and a polycondensation reaction, to form a ceramic film which is noncombustible and outstanding in thermal resistance and weather resistance, and has a high water repellency and water proofing property due to its high density, and also electrical-insulation properties, and shock impact resistance due to its high degree of hardness.
To attain the first object, a speaker diaphragm according to a third aspect has the feature, in addition to the configuration of the first aspect, that the ceramic-type-coating agent is a ceramic-type-coating agent made up of at least one item selected from the group consisting of mixtures of an alkoxy metal and a silicone varnish.
With the speaker diaphragm according to the third aspect, the ceramic-type-coating agent made up of at least one item selected from the group consisting of mixtures of an alkoxy metal and a silicone varnish, which is combined with the fiber-type material serving as the base material of the diaphragm, is hardened at room temperatures or by low-temperature heating, to form a ceramic film which has noncombustibility, thermal resistance, weather resistance and electrical-insulation properties, and is outstanding in damage resistance due to its high degree of hardness.
To attain the first object, a speaker diaphragm according to a fourth aspect has the feature, in addition to the configuration of the first aspect, that the ceramic-type-coating agent is a ceramic-type-coating agent made up of at least one item selected from the group consisting of mixtures of alkali metal salt and silicone varnish emulsion.
With the speaker diaphragm of the fourth aspect, metal alkoxide and metal hydroxide are used for the ceramic-type-coating agent to be combined with the fiber-type material serving as the base material of the diaphragm.
The above ceramic-type-coatin
Ishigaki Toshihiro
Maekawa Koji
Sekikawa Hideo
Shimada Tomoyuki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Chin Peter
Pioneer Corporation
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