US2031134A - Facsimile system - Google Patents

Description

Feb. 18, 1936. H, SHORE 2,031,134

FACSIMILE SYSTEM I Filed Jan. 28, 1933 All A-TORNEY Patented Feb'.` 18, 1936 l y l UNITED STATES `PafrEii'r OFFICE v .2,631,134 I FACSILIILE SYSTEM Henry Shore, Elizabeth, N. J., assigner to Radio Corporation of America, a corporation of Delaware Application January 2s, 193s, serial iva-654,088

s claims. (ci. 17a-69.5)

The present invention relates t facsimile Of these ilgures, Fig. 2 illustrates a sectional 'systems and `is directed primarily to arraneeview of the mechanical filter system; Fig. 3 is ments which will tend to eliminate the streaked a. somewhat detailed view showing the arrange- -or ripple eiects present in many reproduced ment of the braking instrumentality used in 5 pictures. H connection with the mechanical filter system; 5

Such ripples or streaks u susally appear asparal- 'and Fig. 4 illustrates more particularly the relel lines of alternate light and dark shades runsilient coupling between the driving and driven ning in the direction of the line advance. These members.

ripples and streaks are usually Caused by uneven To make reference now to the accompanying 1o sears and uneven driving speeds of the facsimne drawing, it is a1ready known that substantiauy 10 or `picture transmission and reproduction gear. any picture transmitting and' receiving apparatus It is 011e 0f the primary Objects of the present embodies a. scanning drum upon which the pic- I invention to avoid such streaked eiects, which ture of which the e1eetfe-0ptiea1 or other typeof is done by providing wayscnd means by which image representation is desired is suitab1y supthe picture Carrying drum 0r other appropriate ported or upon which'the image representation is 15 instrumentality may be driven at a more uniform produced on o, 'suitably supported recording sneed during the scanning Operation for transsurface. The scanning drum of either the transmission 0r the reproduction Operation for recepmitting or receiving apparatus is driven by some tonappropriate form of drive means suitably con- I zo other objects of the invention are to provide .trolled as to speed in accordance with the desired materially from the general form of transmitting for improved quality 0f the reproduced Picturerate of transmission. Th'e varying intensities Still other objects of the invention are to proof light and shadow of the picture or subject vlde.ways and meufs by Whlch this improved to be transmitted are tested or analyzed by way quahty may be Obi-amable and Stil-1 not depart of a scanning device. The resulting signals are then transmitted to receiving points by way of 25 and recewmg apparatus now m use and as an* a transmitter and amplifier device.` The signals example of which reference may be made for transmitted are then suitably received and amplimechmca'l construcuon to Umted States Patent fied and caused to influence a reproducing device No. 1,803,133, and for electrical construction and to produce a duplicate of the subJect or picture operation to copending application Serial No. located the point of transmission y 30 558,750 led August 22, 1931 jointly by Henry Such apparatus is conventionally shown in Fig. Shore and James N. Whitaker, assigned to Radio Corporation of America. 1 wherein the driving motor is designated as I and Another object of the invention is to provide is arranged. to dnve the.scanmng drm g thvllugh a mechanical filter system which will tend to an gppmpnate mechanical lter devl 03:? make the picture transmission and reproduction deslred ang as shown by Patent No' 8 3 more uniform. 1n addition, it is an object of this above mentlfmed there may be 2P ipeed changing invention to provide a mechanical filter system gear box 4 Intermediate the dnvmg and dnven which can readily be attached to present existing members' 40 picture apparatus. The cut-01T frequency of such The Teeord surface (not shown) Supported by 4o a mechanical filtering System is so chowny that the scanmng drum is suitably analyzed or tested it will be below any frequency which will tend by the scanning devlee 1 and Varying light velues to introduce ripples into the drum. speedthereof are converted in well known manner into Other objects and advantages of the invention, eleetlfleal mpulses t? mfluenee the transmitter oi course, will become apparent and suggest themamphe' 9 from Whleh the Slgnels are directed 45 seh/es to those skilled in the, ari; to which the to a transmitting device II and suitably transinvention is directed by reading the fonowing mined t0 various peints 0f reception by way of Aspecification and claims in connection with the the antenna system I3 or, where desired, by any accompanying drawing, wherein: appropriate form of wire line connecting device. y F1g 1 represents conventionally a, `line diagram If the device is used for receiving pictures, or sig- 50 of the constituent parts of .a picture transmitting nals representing other types of subjects, signals.` or reproducing system; and wherein are suitably received at I3 and passed through Figs. 2,-3 and 4 illustrate further details of the the receiving device Il and thence through the mechanical lter system connected intermediate reproducer amplier to produce from the reprod5 `the driving motor and the picture carrying drum. ducing device 1 appropriate signals to control the 55 image reproduction upon a surface carried'upon the scanning drum 3.

The mechanical filter device 5 applicable for use either in connection with the transmitting device or receiving device is shown in more particular detail in Figs.2, 3 and 4 and it is to this arrangement and its cooperative use in connection with the driving and driven means I and 3 of either the transmitter or the receiver devices to which this invention is particularly directed.

In apparatus used up to the present time, the elimination of the ripple effects above explained has been' attempted by the use of high precision mechanical work. This mechanical high precision work has been made possible by forming the gears very accurately and also by providing very small clearances and careful alignment of thebearing surfaces, all of which vare held to extremely close tolerances. This Work, however, has called for a great degree of mechanical skill and consequently the cost of such precision work has been found to be considerably greater than is justified by the amount of ripple or picture streak elimination accomplished, because even with the nest mechanical layout the ripple is present in the reproduced record at least to some degree.

Therefore, the present system to provide ripple elimination makes use of relatively simple mechanical illter devices which can be applied to a machine which is not absolutely mechanically perfect from a precision viewpoint and yct this relatively simple lter device is capable of eliminating the ripple or vstreaked effect in the reproduced record entirely. -Naturally, this results in a large saving in installation costs, since the filter can be applied to machines already installed at the electrical filter, the flywheel combination, to

be hereinafter described, corresponds to the inductance of the electrical filter, and the braking means, also to be later described in detail, corresponds to the terminating resistance, so that, where it is assumed that this filtering arrangement is to replace, in effect in a mechanical system an electrical half section filter Vin an electrical circuit, the formula for an electrical circuit will hold true` In the mechanical filter R represents the braking force, L the mass, 'that is, the flywheel, and C the resilient drive member of the system. From this it can be seen that if the proper resistance or braking force is not applied hunting or oscillations will result.v

So constituted, the mechanical lter comprises a flywheel 2|, a braking device, generally desighated 23, and a resilient drive means, generally designated 25. 'I'he driving motor I is arranged so as to connect with the shaft 21 which, in turn, has attached thereto by means of a pin 29 an appropriate disk member 3|. The disk 3| is provided at opposite edges with slotted portions 33 and at points on its periphery angularly spaced by a slight amount diametrically opposite pins 35. Upon each pin 35 is attached a spring member 31 which connects, in turn, to a fastening point 39 upon the flywheel 2I so that when the shaft 21 is rotated the driving force is applied through disk member 3I connected to the shaft by Way of the pin 29 so .as to rotate in a resilient'manner the flywheel in the direction shown by the arrow. Also provided on the face of the flywheel adjacent thedisk member 3I are pins 40 which are positioned with the slotted portions 33 but free from the edges thereof. have provided upon the outer surface thereof coverings in the form of cushioning pieces 4I, such as rubber or equivalent, so as to absorb any possible shock due to a sudden pull exerted upon the flywheel due to rotation of the shaft member 21. v

From this description it is seen that as the shaft 21 is rotated the flywheel 2| will also be rotated through the resilient coupling device coupling the flywheel with the shaft. The flywheel itself is rigidly connected to the shaft member 43 which connects with the picture carrying or scanning drum 3 by means of a key or pin 45 so that as the flywheel is rotated due to rotation of the driving motor the scanning drum will also be rotated through the resilient or yieldable connection between the drive motor and the fly- Wheel.

Under such conditions it will be obvious that the mass of the flywheel will to a considerable extent cause the picture carrying or scanning drum 3 to rotate at uniform speed even in spite of slight hunting in the driving motor I. However, it has been found that this mass is in itself insufficient to provide for absolutely smooth and even rotation of the scanning drum since, as was above explained in connection with the formula dened, it is possible for hunting to occur in the absence of any critical damping in the system.

'I'his damping effect is herein provided for mechanically in much the same manner as the damping resistance of the electrical lter circuit.

This resistance or damping is provided according to the present disclosed arrangement by way of a braking device, generally designated as 23. The supporting means for the brake 23 is in a supporting bracket 49 suitably mounted and carried from a support member 5I in which the shaft 21 is suitably journaled in bearings 53 in the same manner that the shaft 43 is journaled in the bearings 55 carried by a support member 51 intermediate the flywheel and the scanning drum 3. 4Upon the support member 49 there is suitably mounted by way of guide members 59 a brake shoe 6I sliding within the support member which is provided with a felt or other suitable covering or lining 63 adapted to bear upon the surface of the flywheel member 2|. The guide members 59 are supported at their upper end, that is, the end opposite the end at which the brake shoe 6I is supported, in a Support member or brake tensioning yoke member B5. Passing through the center of the brake tensioning yoke 65 is a screw threaded spindle 61 to the upper end of which is attached a knurled thumb nut 69 so that in accordance with the position of the thumb nut 69 the brake tensioning yoke is moved either upwardly or downwardly to cause the brake shoe 'and the brake lining 6I and 63to bear with greater or lesser The pins 40.

, upon the brake.

force upon the flywheel surface and thus to vexert greater or lesser braking force.

In order to provide a finer degree of adjustment there is provided .intermediate the thumb nut 69 and the brake tensioning yoke member 65 a suitable tension spring member 1I which serves to regulate and maintain uniform tension It isthis spring member, in combination with the brake, which corresponds to the resistance of .the electrical lter circuit, and it is by virtue of the adjustment and the pressure at which the brake shoe rests upon the iiywheel surface that the damping of the system is altered.

trol gear box 4, would, of course, transmit this velocity to the scanning drum 3 uniformly. However, due to mechanical imperfections in the motor and gear box there will be superimposed upon the uniform velocity higher velocities which would normally be transmitted to the drum. Any variation in acceleration appears as a ripple in the finished or reproduced picture or other subject. I

The use of the resilient coupling and ywheel combination, which constitutes the low pass illter, prevents `these higher velocities from being transmitted. This fact is evident because any` sudden acceleration simply causes the spring member of the mechanical filter system to be placed in tension and so stretched, if the acceleration is positive, or compressed if the acceleration is nega tive. The combined moment of inertia of the` flywheel and the scanning drum resists any tendency for the velocity to change. Consequently, the superimposed velocities will be reduced in this combination. To eliminate completely the transmission of these higher velocities the ywheel and drum must be suitably damped or there is a slight tendency for the system to oscillate at its natural period, as would be true in the electrical circuit, were it not for the damping resistance above described. 'Ihis damping, therefore, is effected in the mechanical lter by means of the braking device and since the spring member provided with the braking device is adjustable the exact value of the damping can be achieved empirically. The ywheel is usually an essential element in the combination since the moment of inertia of the scanning drum alone is `ordinarily not suiiicient to provide a suitable cut-off frequency.

It should be understood that this invention is not limited to a single section low pass filter device since a multi-section filter may prove desirable where the undesired velocities are very high.- The multi-section filter may be provided by theaddition of one or more ywheels and springs. For a two section filter the irst ywheel is mounted on the shaft free to turn, while the second is keyed to the shaft. The second spring is used to couple from the rst to the second flywheel. In general, a multi-section filter will not be necessary.

1 Also, where a small flywheel does not serve to eliminate completely the ripple, a flywheel of increased moment of inertia will accomplish the desired object in much the same manner as the change in the electrical constituents of the electrical filter will change the characteristics thereof.

. `While the invention has' herein been described in aconnection with one of the preferred embodiments which it may assume, it is nevertheless to be understood that it is capable of considerable modification both in form and arrangement of parts, and that such modifications may be made l without departing from the spiritv and scope as herein setforth.

Having thus described my invention, what I claim and desire to secure by Letters Patent is the following:

l. In combination, a driving element, a driven element and a mechanical iilter system connecting the driving and driven elements, said filter system comprising a flywheel rigidly connected with the driven element and resiliently connected with the driving element, and a variable mechanically operable means to critically damp the mechanical filter system.

2. In combination, a driving element, a driven element, a` iiywheel rigidly connected with the driven. means, a resilient connection between the flywheel and the driving means so as to drive the driven element through the flywheel connection, and a variable tension brake arranged to bear upon the flywheel surface so as to critically damp the system.

3. A filter system comprising a driven member, a flywheel rigidly attached to the driven member,

a driving means resiliently connected with the flywheel so as to drive thereby the driven mem-5 ber, and a variable mechanical/braking means to critically damp the flywheel to reduce thereby hunting in the system.

HENRY SHORE.

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