US2338843A - Phonograph recording - Google Patents

Description

Jan. 11, 1944. l... B. GLASER ETAL 2,338,843

PHONOGRAPH RECORDING Filed May 28, 1941 INVENTORS LEO B. G ASER RYO B E RT 6. RANE Y ATTORNEYS Patented Jan. 11, 1944 PHONOGRAPH RECORDING Leo B. Glaser, Cranford, and Robert G. Franey,

Irvington, N. J., assignors to General Instrument Corporation, Elizabeth, N. J., a corporation of New Jersey Application May 28, 1941, Serial No. 395,529

4 Claims.

This invention relates to phonograph recording and particularly to the stripping or removing of the shavings or thread which are cut and severed from the record by the cutting stylus in the recording operation.

The shavings or thread which are cut and severed from the record by the cutting stylus have been a constant source of trouble in professional and home recording of phonograph records. These shavings, in the form of an unbroken thread, are thrown off by the cutting stylus inwardly on to the record surface. The unbroken thread (of substantial tensile strength) as it is cut from the record deposits itself in cumulating concentric rings on the record surface and in doing so attaches itself and tenaciously clings to the face of the record. It often occurs that a section of this thread works itself loose from the record surface and migrates towards the cutting stylus and engages the same, with the result that the thread exerts a pull suflicient to dislodge or move the cutting stylus and its arm from the record, thus causing an interruption or break in the recording operation.

To obviate this encountered difficulty, nu-

merous suggestions have been made and many devices have been used, all designed to remove the shavings or thread from the seat of trouble. In professional recording, a suction device is used to suck up the thread immediately after it is cut, and blower devices have also been employed to blow the thread towards the center of the record before it attaches itself to the record surface. In semi-professional and home recording, the thread is usually brushed towards the center of the record by the operator, various means being employed for this purpose such as felt pads lightly impregnated with oil, metal fixtures lined on their bottoms with felt which. rests on the surface of the record during recording, brushes of light texture, or, as it is usually done, by a sweeping motion of the operators finger. Suction and blower devices are, however, too expensive for home recording purposes. Brushes and equivalent devices are usually only successful on very good recording blanks which have a highly polished low friction surface and are ineffective on recording blanks used in home recording practice. Generally speaking, brush devices are diflicult to handle and to operate because the thread clinging to the record surface is difiicult to dislodge by brushing practice, and the use of these brushes requires constant attendance on the part of the operator. Furthermore, on recording machines with light power driving mechanisms, the engagement of the turntable by the brushing devices is apt to cause intermittent changes of speed of the turntable, resulting in the faulty reproduction known as wow.

In order to eliminate this encountered trouble in recording, records are sometimes made by the method of cutting from the inside out instead of from the outside in. Since, due to the construction of the cutting stylus, the shavings are thrown inwardly towards the center of the record and, therefore, towards the already cut section thereof, the trouble is thus largely, but not altogether, avoided if the record is cut from the inside out.

We have discovered that there is generated on or imparted to the thread in the cutting and severance thereof from the record an electrostatic charge, and that it is due to this charge thereon that the thread attaches itself and tenaciously clings to the face of the record resisting efforts to dislodge and remove the same. We have furtherv found that by freeing this charge from the thread, the cut thread readily releases itself from its clin ing engagement with the record surface and renders itself capable of non-resisting removal from I the record face. When the charge is freed therefrom the thread no longer winds itself cumulatingly' n concentric rings on the record surface but is released therefrom within a cycle of rotation of the record, and may then be easily stripped from the record. We have found that the charge on the thread may be freed by the thread being contacted by a suitable discharging device which may be made to very lightly contac the surface of the rotating record.

The prime object of our present invention,

therefore, relates to the method of stripping the thread from the record based upon these discoveries, and to the device employed in practicing this method.

, To the accomplishment of the foregoing and such other objects as may hereinafter appear, the invention further consists in the method and device hereinafter sought to be defined in the claims and described more in detail hereinbelow in connection with the appended drawing, in which:

Fig. 1 is a plan view of a phonograph recording apparatus of the home recording type, showing the invention applied thereto; and

Fig. 2 is a view of the same with certain parts removed, showing the electrostatic discharging body in operative and in displaced positions.

A conventional form of phonograph recording machine (of the home recording type) is illustrated in the drawing. This machine may comprise a support III, a turntable I I rotatably mounted thereon and operated by any suitable motive means (not shown) provided with a central metallic record receiving spindle I2, 2, reproducing unit l3 shown in its inoperative position mounted on said support I0, and a recording or cutting unit I4 also mounted on said support I and shown in an operative position. As illustrated in the drawing, the recording or cutting unit I4, which may comprise any conventional cutter arm embodying a cutting stylus, is shown operating upon a record I5 which is moving in the direction indicated by the arrow IS, the record grooves already out being indicated as ll.

As hereinbefore described, the shavings which are cut and severed from the record by the cutting stylus in producing the record grooves II, in the form of an unbroken thread, are thrown on" by the cutting stylus inwardly on to the record surface and the thread deposits itself in cumulating concentric rings on the record surface as the record is rotated, and in doing so the thread attaches itself clingingly to the face of the record.

We have discovered as aforesaid that there is generated on or imparted tothe thread in this cutting and severance thereof from the record, an electrostatic charge and that it is due to this charge that the thread attaches itself to the face of the record resisting efforts to remove the same. We have found that this charge is a positive charge, and that by discharging thesame, the cut thread thereby releases itself from the recording surface and is rendered easily removable therefrom.

This method of electrostatically neutralizing and then stripping the thread from the record may be carried out in a variety of ways. We have found one of the simplest ways of accomplishing this is to provide a metallic body contactingthe charged thread, which body may be separate from the phonograph elements and which, therefore, may be quickly moved to operative or inoperative position. In a simple form, such a metallic body may comprise an electrical discharge brush I8 preferably made of very fine metallic wire carried by a suitable base support I9. The material of this electrical brush may,

for example, be brass wire having'a fineness or thickness of .0025 inch. This wire of about, say, one inch trim and having an over-all length of about five inches (for ten inch records) is held by a ferrule 20 supported by any suitable framework such as 2| in turn held on the base support IS. The discharge brush and its supporting elements are so constructed that when the support base I9 is positioned on the phonograph support In, the electrical brush is positioned so that the brush element engages the surface of the record I5 as clearly shown in Figs. 1 and 2 of the drawing. The construction is furthermore such that the brush extends inwardly in a generally radial direction, but at a slight angle to the radius, over a substantial part of the recording surface and the inner end is positioned near the central metal spindle l2, so that after neutralizing or discharging the charged thread, the brush serves to direct the thread as shown in Fig. 1 towards the central rotating spindle I2 which latter acts as a means for stripping the thread from the record. Fig. 2 shows the brush device in both the operative (full line) and the displaced (dot-and-dash line) positions.

When a recording is to be made, the electrical brush is simply placed in the position shown in the drawing. As the record is cut, the shaving or thread indicated as 22 (see Fig. 1) thrown inwardly by the cutting stylus and which attaches itself immediately to the record surface no longer winds itself cumulatingly in concentric rings clinging to the record surface, but is released from adhesion to the record as soon as it passes under and is contacted by the brush, as shown in Fig. 1 of the drawing. Upon brush engagement, the charge is neutralized or freed from the thread and the thread is thereby conditioned for removal. Because of the positioning of the brush element It, the now freed thread is directed towards or moves to the center of the record, as shown in Fig. l of the drawing, and when engaged by the central spindle I2 the thread then wraps and winds itself thereon as the record and spindle rotate. The recording of the entire record may be accomplished without any further attendance to the behavior of the cut thread. The electrical contact brush is of a very soft character and acts primarily as a contact means, the mechanical brushing action thereof being reduced to a minimum.

This method may be manifestly carried out in other ways. Instead of providing a separate electrical brush and arranging the same as above described, the contact element may obviously be attached as by means of a clip to the cutter arm, moving therewith over the recording area. The device illustrated herein, because of its simplicity and easy handling, is one of the preferred means for carrying out the method of the invention.

The method of the present invention, the means employed therewith and the results and advantages produced thereby will, in the main, be fully apparent from the above detailed description thereof. By means of this method the shavings or thread are readily released and then removed from the record, solving the problem and thus eliminating the need of suction, blower or mechanical brush devices. We have found that, an inductive means acting on the principle of lectrosta-tically attracting the charged thread, such as is disclosed in our copending application Serial No. 395,528, filed May 28, 1941, may also be employed in applying the new discoveries, this latter method being preferred because of the inductive action of the means employed, per-' mitting the chargeable element to be spaced above the record without contacting the same and thus without any possibility of marring the surface of the record or afiecting the speed of the turntable. The electrical brush means ofthe present invention, although it engages the record surface, is not a brush in the mechanical sense and does not materially mar the record or interfere with record operation.

It wilrbe apparent that changes may be made in the carrying out of the method and in the means employed therefor, without departing from the essence of the invention defined in the following claims.

We claim:

1. The method in phonograph recording of stripping the thread out from the record by the cutting stylus which consists in providing a metallic discharge brush capable of neutralizing the charge imparted to the thread in the cutting and severance thereof from the record, and positioning the said brush in contact with the record and generally radially over the recording area thereof with the inner end of the brush near the central metal spindle of the phonograph turntable, whereby the charge on the cut thread is neutralized and thereby freed from the record surface and is stripped therefrom by said central spindle.

2. A device for stripping the thread cut from the record by the cutting stylus in phonograph recording comprising a support and an electrostatic discharging element thereon for discharging the charge imparted to the thread in the cutting thereof from the record, the said electrostatic discharging element being carried by the support so as to be positionable above and in contact with the record and the recording area thereof during the recording operation.

3. A device for stripping the thread cut from the record by the cutting stylus in phonograph recording comprising a supporting base and a metallic brush capable of discharging the charge imparted to the thread in the cutting thereof from the record, the said brush being carried by the supporting base and extending therefrom so as to be positionable above and in contact with the record and generally radially over the recording area thereof during the recording operation.

4. The method in phonograph recording of stripping the thread cut from the record by the cutting stylus which consists in providing an electrostatically discharging element capable of neutralizing the charge imparted to the thread in the cutting and severance thereof from the record, and positioning the said element in contact with the record and'generally radially over the recording area thereof with the inner end of the element near the central metal spindle of the phonograph turntable, whereby the charge on the cut thread is neutralized and thereby freed from the record surface and is stripped therefrom by said central spindle.

LEO B. GLASER. ROBERT G. FRANEY.

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