US2012134A - Disk for phonographic recording - Google Patents

Description

Aug. 20, 1935l H. KUB@ 2,012,134

i scratching.

This invention relates to a Patented Aug. 2 0, v1935 I l 'uNrrizo v`v STATES 5 l'ol-"Fic:le;-

disk for phonographic recording, and to a method-or process for' forming such a disk.

One important object of -the inventionl is to provide van improved construction for such disks adaptedto reduce the noise provided by needle Afsecond important object of the invention is 4to provide an improved disk of this character having means whereby it'rnay be visually determined that the disk has reached, through use, the limit of its utility. Y i A third important objectof the invention is to provide anovel process vfor forming such a disk.

In the annexed drawing;

Fig. 1 is the plan of a part of a recording disk according to this invenon in\whicha part of the oxidized film forming a lake layer is removed;

Fig. 2 shows a microscopic enlargement of the section of the same with sound grooves cut thereon and Fig. 3 shows a microscopic Aenlargement of the section of a recording disk with the sound grooves worn away toomuchjor use. f

This invention is an improvement inthe known aluminum recordingv disk. In vthe drawing, I is an aluminum plate covered with the oxidized film 2.by anodeitreatment, which 'film is` permeated by a suitable coloring matter to fill the 'space among the fine crystal particles y3 which form the oxidized film and` thus not only to make "the oxidized lm compact, but also to change it chemically to form a lake coating on the alumin'um plate The.known' a1uminum recording disk is too soft to use a steel needle in the reproduction of sound. That is to say, it has the inconvenience of requiringafibre needle. Moreover, as it has the soundgi'oove easy to be worn, it can be used only few times. Further, its liability to be corroded makes itunt 'for long vpreservation, and also as it is easy tobexid,` it becomes unsuitable for use duringtransportation or preservation. Besides, if the, sound groove is worn out, it is hard to discover it.l According t'o the present invention, an oxidized film coating 2 is formedon the surface of anfaluminum plate by anode treatment, and vby causing a coloring matter to permeate it the' space among thecrystal particles 3 which form the oxidized lm coating is not-only filled, but said oxidized film coating is changed chemically to form a compact lake coat- 4 (o1. zwi-4,2)

ing- 4.V so that when sound is recorded, the lake-A coating of aluminum oxide of high hardness on the surface is pressed down by a hard recordingl `need1e into the unchangedaluminum plate and forms the, bottom ofthe sound groove, thus preventing said groove from being easily Worn even with -a steel or tungsten needle. Moreover; lit lengthens the life of the disk. Furthermore, the

- lake coating Aof colored aluminum oxide on the surface being Very compact, it softens the needle 10 sound and gives it a clear and distinct tone. Also,-

the strong anti-corrosive powerof the lake coat- 'ing vof colored aluminum oxide on the surface enables the disk to stand long preservation.

'I'he sound recording disk of this invention 15 l a surface of considerably high hardness as compared'with the aluminumdisk, and therefore it 'is so difficult to'bend that there is Ano apprehen- 'sion of its becoming uniit for 'use during trans'- fr portation or preservation. Moreover, if thev lake 20 .coating of aluminum oxide which forms the bottom of the sound groove is worn, aluminum which constitutes the core is exposed, so its lustre enables one to discover that the disk has become unsuitable for use. Thus,my disk is most eflec- 25 tiveas a. sound recording disk. Y

Iclaim; 1. A phonograph disk of aluminum anodically treated to oxidize a surface and' having the oxidized surface impregnated with color-ing 30 matter. l

2. That process of producing a blank for phonograph disks which consists in forming a, metallic disk, oxidizing a face of theY disk to producea coating of, an oxide of the metal of which' the. 35

disk is formed. and impregnating the coating with coloring matter chemically reacting on themetallic oxide to form a lake.

3. 'That process of producinga blank for phonograph 'disks hich consists in forming a disk of 4 0 aluminum, subJecting' the (disk to .anodic treat-v ment to oxidize a surface thereof', and impregnat` .ing the oxidized surface with coloring matter.

' 4. That process ofproducing a blank f or phohograph disks which consistsin .forming a disk of

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