US2353547A - Device for mechanical recording - Google Patents

Description

July 11, 1944. A. CRAMWINCKEL ETI'AL 2,353,547

DEVICE FOR MECHANICAL RECORDING Filed Jan. 16, 1941 Patented July 11, 944

UNITED, STATES PATENT orrlcs 1 yua a sfffc fl fmfiwfamg pel, lindhovemh Alien Property Custodian Application January II In Germany 1041, Serial June I No. sum a. 103s 1 Claim. (01. 214-411 Our invention relates to a method and device for mechanically recording a sound track which ticles of film material, or the like. is largely responsible for a hiss during reproduction. It has been suggested to remove this ,dirt from both surfaces of the carrier at the area of the sound track before the sound track is optically scanned. It is also known that a deposit of dust on the lightsensitive emulsion prior to or during the formation of the photographic sound track deleteriously affects the recording and the quality of the track, obtained and therefore the recording and subsequent development and fixation are usually carried out in rooms which are as free as possible from dust.

In photographic sound-recording it is primarily the emulsion surface, of the carrier, 1. e. the

surface on which recording is effected, which should be kept free from any dirt which might intercept ordifluse the exposure light. Any dirt that may what on the surface of the carrier remote from the exposure light, l. e. the exposed surface of the Celluloid or acetyi cellulose supporting layer, has no influence during the photographical recording upon the quality of. the

sound record. During the reproduction only the particles of dirt which exist at the area of the track have an influence and these particles are responsible, for only a small portion of the total Although in photographic recording it is mainly desirable to remove the light-absorbing or light-diif-using dirt from the recording surface of the carrier, we have found that in mechanical recording of the above-mentionedtype it is mainly desirable to remove both light-transmitting and opaque dirt from the supporting surface of' the carrier prior to the formation of the sound track More particularly, if only one surface of a carrier is cleaned and the carrier is wound on a reel. the cleaned surface would engage the other surface, and as the dirt would be attracted to the cleaned surface due to an electrostatic charge on the carrier. Thus, it would be neces sary that cleaning be eflected during the recording process i. 0. after the carrier is unwound from the reel and immediately before recording.

We have found that the presence of dirt on the supporting surface of the carrier results in greatly interfering additional noise during reproduction of a mechanically-recorded track of the above-mentioned type. because a particle of dirt between the carrier and the supp rtin mb r causes a locally-raised position of the carrier. Thus, during the recording the cutting edge of the cutting tool penetrates locally to a greater depth into the carrier and consequently a supplementary width variation occurs oppositethe particle of dirt.

Our invention is of particular importance-in connection with methods of recording in which the width variations of the track are an enlargement of the depth variation, for instance recording of the type described in the U. 5. Patent #1,919,116 to James A. Miller. In such methods of recording the amplitude of the width deformation caused by the presence of a particle of dirt between the supporting surface of the carrier and the surface of the supporting member :vouid be several times the thickness of the par,

icle.

If, 'in accordance with the above mentioned I patent, the track is cut by means of a cutting tool having a V-shaped cutting edgeof a large apical angle, for instance 174 degrees, a particle of dirt having a size of about 20 microns may cause a local track widening of about 800 microns or 0.8 mm., which in the case of a neutral, track width of 0.3 mm. causes a decided local widening of the track which is audible during reproduc tion as an intense dull detonation. Because of width variations which are greatly enlarged with respect to the depth variations, the interfering influence of the presence of dirt in mechanical recording is much greater than in photographic recording. In fact in photographic recording, particles of dirt between the carrier and its support are of practically noimportance, i. e. the locally-raised position of the carrier causes substantially no variations in the shape of the light line in the emulsion. If particles of dirt are present in the path of the recording light, the interfering influence, insofar as they may intercept the light, depends only on their direct size.

We prefer to clean not only the supporting surface of the carrier but also to clean the recording surface prior to the recording because once the track has been out it is exceedingly difflcult to remove any dirt that gets into the depressions of the track.

During mechanical recording of the track particles. of the carrier disengage from the chips cut therefrom and these particles may deposit on both surfaces of the carrier and be pressed into the material of the carrier during the winding operation effected subsequent to recording. Because of this we prefer also to clean the carrier on both sides after the recording and in some cases even again before the winding operation.

We prefer to effect the cleaning by means of a cleaning device comprising a group of directed hairs, for example a strip of velvet or a brush. In this case the dirt slides between some of the said hairs and is retained, so that the cleaning device is capable of absorbing considerable dirt before being saturated.

If the carrier has been cleaned in the manner described above, any dirt that exists on the carrier andin some cases in the recording device is prevented from depositing on the carrier dur ing mechanical recording and re-winding. If the sound track is optically reproduced after the mechanic'al recording, it is advisable to subject the the boundary of the track due to the particle II will be about times the thickness of this particle.

It should be noted that the above diiliculties occur not only .when the track is surrounded by opaque portions. as shown, but also when the track is cut into a transparent layer and is then blackened. In the latter case the deformation causes a sharp projection of the blackened track.

The recording device diagrammatically shown in Figure 2 is used for recording a variabledepth and variable-width sound track in a carrier or tape 21, which may be of the type shown in Fig.1. Ilf'he carrier -21 is unwound from an unwinding reel II and moves in the direction indicated by thearrows. More particularly, the carrier 21 passes over a guide roller ll. through a cleaning device ll, over a guide roller ll, over a recording roller 20, through a cleaning device 22, through an optical scanning system 23, over a roller Ill and onto a winding reel 24. A roller ll presses the carrier against roller 20.

carrier to another cleaning operation prior to v the optical reproduction in order to remove any dirt which may be deposited on the carrier during its passage along the guide rollers and guide surfaces.

In order that the invention may be clearly understood and readily carried into effect we shall describe the same in more detail with reference to the accompanying drawing. in which Fig. l is a perspective view of a carrier and shows a cutting tool,

Jig. 2 is a diagrammatic view of a recording system comprising a plurality of cleaning de- :g. 3 is a partly-sectionized side view of a cleaning device, and

Hg. 4 is a side view of a cleaning device according to another embodiment of the invenflan.

me carrier shown in Fig. 1 comprises a thin covering layer ll of Opaque material provided on a supporting layer H of a transparent material of good cutting properties. The carrier is moved at a constant speed in the direction of the arrow 2 over a supporting member H, which may be a stationary block as shown. or s. rotating roller as shown for example at 2| in Fig. 2, while a cutting tool i2 is vibrated in the direction of the double-headed arrow I in accordance with the sound being recorded. The cutting tool II, which has a V-shaped cutting edge having a largeapical angle, for instance an angle of about 174', removes portions of the opaque layer II and of the cutting layer II to form in the carrier a sound track I having depth variations and width variations which are an enlargement of the depth variations.

If there is a particle of dirt IS on the supporting surface of the carrier, 1. e. the surface which bears upon the surface of the supporting member ll. the carrier will be slightly raised locally from the surface of member I. As a result the thin covering layer l0 will be raised at this point and the sound track at the location of the particle II will have a width greater than that which corresponds to the ampiitude of the cutting tool. With a V-shaped The recording is effected at roller 20 by means of a recorder 2| which may have cutting tool of the type shown in Fig. 1. As suitable recording devices, scanning devices and driving devices are well known in the art, further description or illustration of the same is believed to be unnecessary.

When carriers of non-conductive substance, such as carriers comprising a gelatin cutting layer superimposed on a Celluloid supporting layer, are unwound from an unwinding reel in a dry atmosphere, they receive an electrostatic charge which attracts many particles of dirt. Furthermore, dirt is deposited on the carrier at points at which the carrier is guided through the recording mechanism and at which the edges pass along flanges or plates. 1. e. along the rollers i0 and I8. To remove this dirt the cleaning device I! is arranged in front of the point of recording i. e. so as to clean the carrier before the track is cut. As the electric charges also exist on the carrier after cleaning and because of other factors causing deposition of dirt on the carrier, for example at the guiding points, this cleaning operation should be effected immediately prior to the recording of the track. The cleaning device I! therefore is arranged as close as is constructionally possible in front of the recording device 2|. Because of the lack of space it is not possible to locate cleaning device I! between the last guide roller II and the recording roller 20, and this is why it is arranged after the next to the last roller IS.

The cleaning device I! cleans not only the supporting surface but also the recording surface of the carrier because the particles of dirt existing on the latter surface might enter the depressions of the cut track and influence the light during reproduction. Furthermore, its should be noted that due to the varying depth of the track it lwould .be very diillcult to remove such paric es.

During cutting, the material removed is in the form of a continuous chip or shaving which is generally removed from the point of recording by auction. However, in practice small particles are disengaged from this shaving and might deposit on the carrier even after cutting. There is the danger that such particles, if they get between the carrier and the surface of the supporting member, or during winding between the turn of the coil, may be pressed into the material of the terrier. Because of this we prefer to repeat the cleaning as soon as possible after the recording.

In the recording device of Fig. 2 the second cleaning member 22 is located after the recording roller 20 and the roller ll, and cleans both surfaces of the carrier. before the opticc-electrical reproduction "for checking the recorded sound track is effected by means of the device 23, the carrier is made as free from dirt as possible on both surfaces. The cleaning member 21 is therefore arranged in front of the point of optical scanning device 21. When the carrier is then wound on the winding reel 24 there is as little dirt as possible between the turns. If desired, cleaning my be affected again immediately beforewinding, i. e. by a cleaning device (not shown) located between reel 24 and roller 5..

We may further clean the carrier when it is rewound on the unwinding reel I, which is generally of an interchangeable form. This cleaning operation is effected by a cleaning device 2! in the rewinding path (indicated by a dotted line) of the carrier in which path the carrier engages a guide roller 2!. This cleaning operation may be effected on both sides of the carrier or on the supporting surface.

The cleaning devices I1, 22 and I! of Fig. 2 may be of the construction illustrated in Fig. 3. The device shown in Figure 3 comprises a housing ll provided at its ends with two openings '2 and SI for the passage of the carrier 21, which moves in the direction of the arrow 36. Within housing Si and bearing upon the upper surface of the carrier 11 is a piece of velvet I while a second piece of velvet 35 engages the lower surface of the carrier and is pressed thereto by a pressing block I! and two compression springs 32. The short. grouped hairs of the velvet u and 3!, which extend substantially perpendicular to the surface of the carrier brush away the particles of dirt loosely-seated on the surfaces of the carrier. The width of the said strips is greater than the width of the carrier itself so that also the lateral sides of the latter are cleaned by the hairs.

If this brushing action is not suillcient to remove the dirt, for example because the adhesion of the dirt to the carrier is greater than the force that the hairs can exert on these particles of dirt, the adhesion of the cleanin member may be increased artificially by the addition of substances of greater adhesion, such as liquids and in some cases tacky or greasy liquids or greasy substances in general. As examples of such substances we may mention sulfonated resinousoil or olive oil. For this purposepa feed tube 30 extends through an aperture 31 provided in the top of housing II near the point at which the carrier 21 enters the cleaning device. The aperture 31 extends at least throughout the width of the carrier and a small supply of the desired liquid or fat is passed through the tube 38 to the velvet and the surface to be cleaned. The substance applied is removed together with the dirt by the portions of the velvet strips remote from the aperture 81.

If cleaning is eifected by means of a volatile Thus, we ensure that liquid such as carbon tetrachloride with some alcohol and water, the recording surface of the' carrier may also be treated in the above manner. The portion of liquid which is not removed in the further part of the cleaning members volatilizes from the track. Non-volatile liquids and fats can be used for cleaning only the supporting surface of the carrier but they have to be removed together with the dirt by means of a strip of velvet.

The cleaning member shown in Fig. 4, which preferably serves for dry cleaning, comprises four brushes I supported in carriers II. The bristles of brushes ll are not at a right angle to the surface of the carrier 21, as in the case of the hairs of the velvet in Fig. 3, but from an acute angle therewith. Furthermore, the bristles are in "anti-direction with the direction of movement 36 of the carrier 21 i. e. they form an obtuse angle with the surface of the incoming carrier. The length of the bristles is of the order of magnitude of 10 mms. i. e. many times greater than that of the velvet, and therefore each bristle per se must be stiff in order that it may form an angle with the surface of the carrier in spite of the pressure of the bristles on the carrier, i. e. in order that it may not become located in the plane of the carrier. The necessary pressure of the bristles on the surface of 'the carrier is procured by the resilience of the skilled in the art.

What we claim is: I

In a device for mechanically recording on a carrier a sound track having depth variations and enlarged optically-reproducible width variations, an unwinding reel for the carrier, means for recording the track disposed at a recording point, and means for removin dirt from the supporting and recording surface of the carrier at a point between the unwinding reel and the recording means, comprising a housing provided at its ends with openings through which the carrier passes, a brush member supported by one inner surface of said housing and comprising a plurality of hairs directed towards one surface of the carrier, a second brush member supported by a movable element of said housing and comprising a plurality of hairs directed towards the other surface of the carrier, resilient means interposed between said element and a second inner surface of the housing for urging the hairs of said latter brushing member towards the carrier, a source of adhesive cleaning fluid and means for supplying said cleaning fluid to said brushing membersand for maintaining selected portions thereof substantially saturated.

ARNAUD CRAMWINCKEL. CORNELIB J OHANNES DIPPEL.

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