US1820335A - Intensity control - Google Patents

Description

Aug. 25,1931. o. voN BRONK E1' AL 1,820,335

I INTENSITY CONTROL Filed Aug. 6, 192'?` L-B AT RNEY Patented Aug. 25, 1931 UNITED STATES PAfria-N'i- OFFICE orfio vou BRONK AND HANS mirror, onisnnmn enniwmivxnssienoas ToGEsELL- SCHAFT FUR DRAHTLDSE TELEGRAPHIE M. OF BEAR-LIN, IGrillillVlIANY, A COR? PORATION 0F GERMANY Iiv'rnnsifry ooNTRoL Application filed August `6, 1927, Serial No. 211,084,211141 in Germany August 9, 1926'. I

Intensity variations or {iuctuations due to atmospheric conditions are rathercommon in Wireless telcgraphy. While vsuch fluctuations in reading telegiaphy signals and in telephony and also in high-speedvreception with recorder devices still allow Ofcomapparently unavoidable even by repetitions of the massage or text.

The present invention discloses ways and means whereby the influences of such liuctnations upon the quality vofthe pictures can be eliminated or at least greatly diminished. Fundamentally speaking, the invention consists in that in a system for transmitting and receivingT pictures by radio, orV even land line, the receiver or the picture, reproducing apparatus is given a changing' sensitiveness, the latter being adjusted in accordance with the prevailing intensity or volume of reception. Hence, if reception is strong, the sensitivity must be made small, while the sensitivity must be great whenever tlie incoming signals are Weak. y This can be accomplished, for example,l by providing a receiver arrangement with an integrating action during a period which is long f compared with the radio frequencycperiod or picture-element period (fractions of a' second), for example, a simple rectifier with collecting condenser produces a direct current whose strength varies in conformity with the volume of reception, saidv direct current altering, for instance, in the shape of a grid potential, the sensitiveness of the picture reproducing apparatus in the desired manner. Since the fading or inten'sityuctnations are generallyof a period amounting to several seconds, such an integrating device of low inertia is capable ofk compensating 'a large part of the intensity fluctuations.

Instead rent in an integrating manner from part-of the picture, the following method could also be used :l ,f j

The picture is provided marginally with of deriving the regulating cur-r la distinct or separate strip of medium blackness, consisting, for instance, of a shading as illustrated vby-portion S ofthe accompanying drawing. If, then, Zisthe direc-.- tion ofthe lines in the 'transmission ofthe picture, for, each line, during a certain fraction `of the time, the mean transingS will be present. More particularly speaking, the saidstrip S may be used for the purposeofadjusting the Asensitiveness of "the apparatus for the next line inthedesii'ed manner.- Y

By the accompanying drawingswe have shown by Fig. 1 one form which our invention may assume, and by Fig. 2 a modified form of the invention illustrating ka different volume control system.V It: is to the produced'light may be directed through lenses ,or any other preferred means to Vinf be understood,(however, that such-forms FasV are illustrated'are purely by way of-example, and we believe ourselves to be limited' onlyin so .far as is necessary from thel 'mission intensity- Whicli is produced byV shadfluence a light sensitiver stripI Bon a receiv- Ving drum B. VThe receiving drumB is mounted upon'a shaft Cv and is:turned in 'any preferred mannerby a motor or other means of known arrangement (not shown).

The movement of the light source M is likewise accomplished by means of the same motor that rotates the drum B and` through a gear mechanism Vthe motork is adapted `to move thelight source M back and yforth upon a guide strip D ata speedwliich will be in` ysynchronisni withl that of a similar light pick-up mechanism at the transmitting sta-y tion. As the light source M moves back and-7 forth upon the guide strip D, upon reaching the end of each stroke means is preferably provided for advancing the drum B a small fraction of an inch for recording the next band of the picture on the light sensitive strip B. In the preferred embodiment of our invention the light sensitive strip B is provided at one edge (or even at beth edges) with an area or strip of darkened or shaded material S of which the intensity with which the light from source M for a given light intensity at the transmitter should shine through has been determined, since, at the transmitter a shaded strip or area of like intensity to iniiuence a light sensitive means controlling the transmitted. energy is provided.

At the same time that the light source M has been moved so that it is above the darka cned strip S of the light sensitive film B,

- tensity of light from source M to produce the predetermined amount of illumination upon the photo cell P is unobtainable and means must be supplied to increase the sensitivity of the system to produce a finished picture of even light distribution. Therefore, a standard of light intensity M which. is the same as that which is passed through a like strip S at the transmitter to influence the photo cell or" the transmitter has been provided, and each time that the light source M is advanced to reach the portion designated E of the guide strip D, a switch J is closed. The closing of switch J lights the source M by means of a battery L. The switch J includes a conducting strip E which has been made a portion of the guide strip D and a conducting strip made a part oic the portion M including the light source. The circuit for the light source M is closed through parts E, K and the bottom contact of the switch J.

Light shining from the light source M is carried through a screen S of the same darkness as the screened or shaded portion S which has been .made a part of the light sensitive film B. The light from M by means of lenses or other instrumentalities is directed to a photo cell P and by which means a current is caused to fiow owing to the fact that the light changes the resistance properties of the photo cell. The currents flowing through photo cell P are directed to an amplifier A where amplification takes place. Likewise the currents flow from the photo eel] P due to the influence of the lieht v1,eeo,335

from source M when the same has been moved across guide strip D to such a position that its light is directed upon the shaded portion S of the light sensitive film or strip B are directed to the ampliiier A" where they are amplilied. One terminal of each amplifier is preferably connected together and a connection between this common point and a magnetically controlled rheostat F provided with actuating coils H and H at the coininon point on said coils is made.

The other terminals oit the amplifiers A and A are connected to the free end ot coils H and H respectively. it is thus :ren that if the current strength from each pliier is the same, the currents iliiiwing Jrein the windings H and H will be ci' equal intensity and there will be no movement of the armature Gef the magnetically controlled rheostat. However, it the current strength produced. by the incoming signal. energy to lie'ht the source M produces less intensity upon the photo cell P than the source M produces upon the photo cell P, it is readily seen that the armature G will be drawn toward the winding H.

Associated with the receiver and amplilier A is a circuit in which the grid b. be controlled automatically by in light intensity of. M over tha.J which variations may be producer con'nnonly known characteristics ot or other known effects. For any such tion, the sensitivity of the :.nn )liily t., teni A must creased and, therefore, upon fading cond ons taking place, the arma.w ture G will be drawn toward the winding H in such a fashion as to decrease the amount of resistance F in the grid bias control circuit which comprises the resistance F (forming a part of the nui-rjnetically coin trolled rneostat), the battery L and the grid circuits of certain tubes in the ampliiier system A. Since the external influences or fading, static and all other disturbances commonly known as strays, Y

ids, etc. ydo not usually occur with rapidity than the time required for source M 'to traverse the recording strip B, it is suiiicient, in order to obtain a finished picture et' unitaria inten-- sity, to regulate the sensitivity of the i ceiving system at each stroke ot the li` source M across the hlm B. However, it is also within the scope of this invention te control the sensitivity et the sj ste means of the shaded area S on each edge o'i' the recoro` strip B, and such forni ei invention will be substantial duplication o the eleinen s herein set iorth for a c .7 d area on one edge oi' the rccornnig sh; strip.

This system might also be controller. then by an operator to adjust the eener-.licences or the system in accordance with the current le@ oiving through the shaded portion S of the f picture stiip. This arrangement offers the merit that the regula-ting actions are more frequent so thatcompensation is aliected more rapidly than the one before described. Y

vTo be sure, special change-over means are required in order that during the time S only the sensitiveness is regulated, Whereas during the `rest of the time the picture istransmitted. y

By 2,- a modified formy of arrange-v nient is shown.l This arrangement is substantially like the arrangement `shown by Fig. l in that, signals ai'e received upon the antenna N and passed through ythe receiver and amplifier A where they are used tov control intensity of a lightv source M for the purpose of producing a record upon a record strip yB carried by the druinB. In parallel relation to the youtputiterminalsa, (i of the receiver and amplilier A or, Vas shown by Fig.` 2, in parallel to the input terniinals e, e or' the receiver ancL amplifier A,

a senaiate reetif ino' and am olif inft s stomk l D C 7 is inductively coupled. This rectiliying and amplifying system preierably consists in the usual type of thethree electrode vtype vacuum tube for the purpose ot' producing.

ance r associated With the receiver and am,

plilicr A so as to control `the grid bias on the amplifier A and thus provide an arrangement wherein the intensity of the received signal may regulate the sensitiveness of the picture reproducing apparatus in the desired manner. The arrangement shown by Fig. 2 forms an integrating device `oi loW inertia which is capable of compensating for a large part of the intensity fluctuations.

Having thus described our invention, What We claim is :V n. l

l. The method ot eliminating intensity variations in radio picture transmission and reception which comprises providing an arca' of shade upon at least one edge of the picture and controlling the sensitiveness of ri-'reproducing apparatus by the. intensity of reception on said area of shade vat each line of the picture.

2. In an apparatus sio'nand reception, means for receiving and visibly recording messages, and light sensifor eliminating intenf siiy fluctuations in radio picture transmistivemeans for automatically controlling the sensitivity of the receiving means in proportion to the mean intensity of signal re'v c ception at any given time period.

l 3. An apparatus for eliminating intensity fluctuations in radioy picture vtransmission and reception, comprising, means for receiving signals, means for recording messages in` accordance With saidpreceived signals, meanstor automatically controlling the sensitivity of `'said picture receiving apparatus in proportion to the mean intensity of signal reception at any `given "instant, said means including a Vlight sensitive means for controlling the grid blason said receiving apparatus. n y 4l. An apparatus for eliminating intensityV fluctuations in radio ti'ansinission and rc-V ception systems, comprising, light responsive means' or automatically determining the meanfi'ntensity of reception at predetermined time intervals, and meansv for controlling theA sensitiveness of the receiving system Ain pro-portion tothe deviations in the moan intensity at said,predetermined time intervals from a predeterminednormal intensity of reception.V

5. A system cluding, means for producing light intensities of a value governed in accordance With the intensity of reception atv any given iiistant, means for periodicallycomparingthe said light intensity produced with a constant predetermined normal light intensity value,

and means controlled byvariations in said. lirst named light intensity produced from for receiving `facsimile, Vinsaid predetermined normal value oi' light in- Vtensity for controlling the sensitiveness ol the said receiving system.

6. An apparatus vfor eliminating intensity fluctuations in radio transmission aiidreception systems comprising,

means for comparing the intensity of reception Y at said chosen time intervals with a normal standard of reception, and means for controlling the sensitivenessof the receiving system in proportion to the variations in the mean intensity of reception vfromv said predetermined normal standardY value.:

7. A system for receiving-'facsimile .including, meansy for receiving signals and producing vtherefroi'ii light intensitiesjoiE la value governed lin accordance `with the intensityfofA reception of any given instant, means for periodically comparing the said light intensity produced With a predetermined normal constant light intensity value, v and means controlled by variations in said first named light intensity produced fromv said normal value for applying a controlling bias to saidreceiving meansV for governing thesensitiveness'of the said Areceiving system.

a light controlledv means for determining the intensity or' re-r ception at predetermined time intervals,

lio

8. The method oit eliminating intensity fluctuations in radio picture transmission and recelition systems, Which comprises, providing an area of shade upon at least one edge of the picture, directing a light beam governed in intensity by the strength of incoming signals throi'lgh the shaded area at the receiver, providmg a second shaded. area of like density, directing a light beam ot intensity equal to 'the normal light intensity on the tirst shaded area through said second area, comparing the light intensity passing through the second shaded area with that through the first shaded area, and controlling the sensitiveness of a receiving apparatus in accordance with differences in the amount of light passed through each oit said areas.

t). The method ot controlling the sensitiven'ess ol.: radio acsin'iile receiving systems which includes, ce itrolling a light source by received signal pulses, directing the light produced through a shaded area of predetermined density, periodically illuminating a light source et intensity corresl'ionding to normal intensity oli said lirst light source, directing the oght beams issuing through said second light source through a shaded area of like density to said lirst shaded area, comparing the amount el light passed through each of said shaded areas from both of said sources, and controlling the sensitiveness ol the receiving` syst-em in accorilance with variations in the intensities oit ythe said lights passed througli each of said areas.

l0. In a picture receiving system, a light source, an amplilier, means associated with said amplifier for Aillumunitmg said light source and producing an intensity ol illumination. therein proportional to the strength of incoming signals, means or periodically illuminating a source of constant light intensity, `leans for comparing the relative l .intensities ot each ot said light sources, and

moans governial by the variations in light ii'itensity oit said lirst source ot said constant source for applying a compensating bias potential upon said amplifier, whereby the strength et the received signzns is controlled in proportion to the conditions of reception at any given i stant.

ll. In a picture receiving system, a light source, an ainpli'lier, means a sociated with said amplifier lor illuminating said light source from that of said constant source for applying a compensating biasing potential upon said ampliiier, whereby the strength et' the received signals is controlled in proportion to the strength of reception at any given instant;

l2. ln a system for receiving pictures and the like, a receiving and amplitying means for receiving signals :trom a distant point, a light source, means associated with said receiver' and amplilier for illuminating said light source and producing light intensities therefrom governed in accordance with the strength ot said received signals, a light sensitive surface tor producing pictures having their density controlled by the varying intensities of light shiiiing hercon, a shaded area on one edge oit said light seni-sitire surface, i means tor directing said variable strength light through said shaded area, a photo cell sensitive to 'the light projected through said shaded area, a source ot constant lignt intensity, a second shaded area, ot like density to said first sha-fled area, means lor directing the light issuing vfrom said constant source through said secoiui shaded area, a second photo cell, and means lier subjecting said photo cell. to said light Missing through said second shaded area, means tor coniparing the relative intensities of each ot said light sources by the currents produced thereby through said photo ci i, and means controlled by variations in current flow through each ot said photo cells for applying a variable controlling bias potential to said receiver', whereby said irst inlined source oit' light intensity is controlled in accordance with the strength oiE vthe received signals at any instant.

13. In a signalling apparatus, means for receiving and recording signals as picture messages thereof, means determining the average intensity signal reception at predetermined time intervals, means for comparing the intensity ot reception at said chosen time intervals with a predetermined optimum intensity et re option, and means responsive to variations of said received intensities 'trom said optimum intensity for varying the sensitivity et the said receiving means to receive signals.

ll. In a signalling system ttor receiving facsimile messages, means tor translatia,- said received signals into light intensities of values proportional to the average intensityo't reception at predetermined time intervals, means for comparing 'the light intensities produced with a constant predetermined normal light intensity value, and means responsive to differences in said light intensity values for controlling the sensitivity o'l the receiving means.

1:1 In a signalling system for receiving picture messages, means for producing light at predetermined time intervals oit an intensity proportional t the intensity of the received signals, means for comparing the' intensity of the light produced With a constant predetermined normal lightintensity value, and means responsive to differences in said light intensity values for varying'the bias on the receiving means in accordance With the intensity of signal reception at said y predetermined time intervals.

16. An apparatus for eliminating intensity fluctuations in radio reception systems comprising means for receiving signals, means 'l'or amplifying said received signals, means for converting said amplified signal energy into proportionate light intensities for re-k cordmg purposes, and means for controllingtlie amplification of said signals over predetermined periods of time in accordance Vwith the intensity of reception during 'a relatively small portion of said predetermined time period.

17. An apparatus for eliminating intensity `liuctuations in receiving systems comprising means for receiving signals, means fory recording messages in accordance with said received signals, and means for automatically controiling the sensitivity of said signal recording means in accordance with the strength of signals received during predetermined periods of ltime separating successive recording actions.

18. An apparatus for eliminating intensity luctuationsin radio reception systems comprising means 'for receiving signals, means for converting received signals into light impulses of intensities proportionate 'to the received signals, and means for periodically controlling the received 'signal energyin accordance With the intensity vthereof as received over time periods substantially less` than the time period for Which the controlk is to be effective. y

OTTO rvoN BRONK. HANS RUKOP. Y

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