Abstract In order to distribute electric charges that build up on the surface of record discs and also to drain them away, a cover sheath is provided for storage of the record disc having at least its surface in contact with the surface of the inserted record disc made of conducting material. The cover sheath can be made of metallized paper or metallized synthetic resin film on the same kind of machinery as is used for making conventional sound record dust covers of paper of synthetic film. If the material is metallized on only one side, it is provided with a cuff around its opening so as to lead charges to the outside where they can be drained away by a conducting storage structure. If the material is metallized on both sides, instead of providing a cuff, electrical connection of the two metallized layers should be provided. Normal handling of sound records kept in non-conducting cover sheaths produces electric charges providing a field strength of the order of 100,000 V/m at 5 am from the record disc surface, which explains the generation of crackling noises when the record is played. The charges can be reduced greatly by insertion in a metallized cover sheath and still more if the cover sheath is grounded, even through a poor conductor, during normal storage.
A protective cover sheath on a synthetic resin plate such as a sound record disc, capable of reducing electrostatic charges on the plate and the consequent attraction thereof for dust, constituted by a flat pocket made of flexible insulating sheet material which is metallized on both sides with a continuous vapor-deposited metal coating and which fits over and covers the synthetic resin plate and is in area contact with both face surfaces therof, the metallizing layers on opposite sides of said material being electrically connected with each other.
Claim 2
Dependent Claim
88 words
A protective cover sheath on a synthetic resin plate such as a sound record disc, capable of reducing electrostatic charges on the plate and the consequent attraction thereof for dust, constituted by a flat pocket made of flexible insulating sheet material which is metallized on both sides with a continuous vapor-deposited metal coating and which fits over and covers the synthetic resin plate and is in area contact with both face surfaces therof, the metallizing layers on opposite sides of said material being electrically connected with each other.
Claim 3
Dependent Claim
23 words
A protective cover sheath on a synthetic resin plate as define in claim 1, in which said pocket is made of metallized paper.
Claim 4
Dependent Claim
48 words
In combination, a plurality of protective cover sheaths as defined in claim 1, each covering a different synthetic resin plate, means for holding said sheaths and their contents in a storage position, and means for connecting the electrically conducting material of said sheaths to an electrical ground potential.
Claim 5
Dependent Claim
127 words
A protective cover sheath on a synthetic resin plate such as a sound record disc, capable of reducing electrostatic charges on the plate and the consequent attraction thereof for dust, constituted by a flat pocket made of flexible insulating sheet material metallized on one side with a continuous vapor-deposited metal coating and fitting over and covering the synthetic resin plate in such a way that the metallized surface of said flexible material is in area contact with both the face surfaces of said synthetic resin plate, said metallized sheet material of the pocket being folded over outwards as a cuff (3) at the entrances to the pocket to provide a portion of said metal coating on the outside of said pocket for readily grounding said coating electrically.
Claim 6
Dependent Claim
127 words
A protective cover sheath on a synthetic resin plate such as a sound record disc, capable of reducing electrostatic charges on the plate and the consequent attraction thereof for dust, constituted by a flat pocket made of flexible insulating sheet material metallized on one side with a continuous vapor-deposited metal coating and fitting over and covering the synthetic resin plate in such a way that the metallized surface of said flexible material is in area contact with both the face surfaces of said synthetic resin plate, said metallized sheet material of the pocket being folded over outwards as a cuff (3) at the entrances to the pocket to provide a portion of said metal coating on the outside of said pocket for readily grounding said coating electrically.
Claim 7
Dependent Claim
48 words
In combination, a plurality of protective cover sheaths as defined in claim 4, each covering a different synthetic resin plate, means for holding said sheaths and their contents in a storage position, and means for connecting the electrically conducting material of said sheaths to an electrical ground potential.
Claim 8
Dependent Claim
23 words
A protective cover sheath on a synthetic resin plate as defined in claim 4, in which said pocket is made of metallized paper.