US2066261A

US2066261A - Facsimile receiving system

Info

Publication number: US2066261A
Application number: US76225A
Authority: US
Inventors: William G H Finch
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-11-11
Filing date: 1936-04-24
Publication date: 1936-12-29
Anticipated expiration: 1953-12-29
Also published as: US2066262A

Description

Dec. 29, 1936. W, G, H, FlNCH 2,066,261

FACSIMILE RECEIVING SYSTEM Original Filed Nov. 11, 1935 g Y 0" ,f 22 2a 5f l 27 n 25 j* Fig: 2

.Q l/ $5 gl- RECEIVER T PEA/fbE? 4/4 ll'l'lwy' INVENTOR. 5g 59 WILLIAM G. H. F/NCH E ATTORNEY.

Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE Divided and this application April 24, 1936, Serial No. 76,225

8 Claims. (Cl. P18-5) This invention relates to facsimile systems and more particularly relates to facsimile receivers utilizing local energization for picture recording controllable by the facsimile signals, and is a division of my co-pending application Serial No. 49,222, filed November 11, 1935, now Patent No. 2,060,778. issued Nov. 10, 1936.

Facsimile signals generally comprise amplitude modulated currents varying in accordance with the elemental shading of the picture being transmitted. In black-and-white picture transmission, varying intensity facsimile signals are dispensed with but make-and-break signals or signais of maximum and zero intensity correspond- :5 ing to black-and-white picture portions respectively are transmitted as is well known by those skilled in the art.

Recording or translating picture systems heretofore have depended upon the energy of the 'o amplified received signals to actuate the recording stylus. I contemplate local energization of the facsimile reproducer at a predetermined frequency to compose the reproduction by markings caused by the local ener-By, and adjust u parameters so that the received facsimile signals are sufficient to electromagnetically prevent the recording stylus from marking the record sheet for the white picture elements.

The frequency of the local energization proso duces a plurality of adjacent discrete dot impulses 4 to build up the facsimile reproduction by the discrete dots. A half-tone reproduction results from such nn arrangement. Pictures for newspapers are of the half-tone variety to facilitate :s printing. My present invention reproduces piciurvs having n half-tone effect. A further modincnilon of my present invention resides in the direct etching of a zinc plate by the facsimile recording stylus to yield a metallic picture record n suitable for newspaper mat reproduction, dispensing with intermediate photographic steps.

li. is accordingly anobject of my present invcntion to provide novel facsimile reproducing means utilizing local encrgization for reproduction All power controlled by the incoming signals for lmproving translation efficiency.

Another object of my invention is to provide novel facsimile reproduction means whereby halftone reproductions are effected from otherwise so normal picture transmissions.

A further object of my present invention is to provide n novel facsimile reproducer for directly recording a half-fone picture on a sheet or merhunicnily ctchinrz a metallic plate.

be These and other objects of my invention will become apparent in the following description taken in connection with the drawing in which:

Figure 1 is a schematic illustration of a commonly used chopper amplitude modulated facsimile signal system. 5'

Figure 2 is a preferred modification of an electrodynamic facsimile reproducing system utilizing local signal energization.

Figure 3 is an electromechanical reproducerI modification of Figure 2. 10

Referring to Figure l, a beam of light I0 generated by light source II is focused by lens system I2 to a point I3 on a picture record Il secured to the drum I5 rotated in a predetermined manner by shaft I6. I'he picture I4 is also moved axially 15 so that the light point I3 will in turn continuously scan the picture. The refracted light beam Il is focused by lens system IB to photoelectric cell I9. A chopper wheel is interposed between the light beam Il and photo-cell I9 in 2o order to break up otherwise slowly varying picture currents to produce a predetermined audio carrier frequency so that an ordinary instead of direct current photo-cell amplifier 2| connected n to the output of photo-cell I9 may be employed. 25

'I'he output of photo-cell amplifier 2i is coupled to a power amplier 22 by coupling transformer 23. The output 24-25 of audio amplifier 22 represents the facsimile signals tobe transmitted either over wire line 26-21 when switch 30 28 is closed on contact 29; or radiated by antenna.

I0 when switch 28 is closed on contact 3| connecting audio amplier 22 to the radio frequency transmitter 32 modulating the carrier wave generated by the radio frequency oscillator 35 33 in a manner well known in the art.

The picture record I4 of my present invention preferably contains a black-and-white picture for transmission so that the facsimile signals represent a maximum signal intensity for white and a minimum signal intensity for black picture segments. g

When transmission of the facsimile signals is by radio frequency carrier wave, the corresponding radio receiver 40 is utilized in conjunction with 45 receiver antenna 4I. If the radio frequency oscillator 33 generates a carrier wave in the ordinary radio broadcast band, an ordinary broadcast receiver 40 may be used. The output 42-43 of receiver 40 is normally connected to a loud speaker unit Il when the switch is closed on contact 48. However, for facsimile reproduction according to my system, it is only-necessary to turn the switch I8 on contact Il to introduce the u facsimile signals to the input 48-49 of rectifier unit 50.

The rectifier unit 50 is represented as a copper oxide unit connected in a well known manner to convert the alternating current signals due to the chopper action of wheel 20 or other audio carrier means to the original black-and-white signals of the picture |4 at the output 5|-52 thereof. Rectifier 50 although illustrated as a copper oxide rectifier may be of the electronic type but a copper oxide unit is preferable for simplicity and ruggedness.

The output 5|52 of rectifier 50 is connected to a movable coil 53 wound on coil form 54 floatable in the air gap of the electrodynamic unit 55. The construction of unit 55 is similar to that of the present type electrodynamic loud speaker and comprises a direct current winding 56 about a central core 51 energizedby a direct current source 58 through a series connecting rheostat 59. A circular rim 60 forms an annular air-gap with the circular central core 51. Coil form 54 is compliantly supported upon the core 51 by resilient member 6| mounted on post 52 secured to core 51. A stylus 63 held in retainer 54 is mechanically connected to the suspended movable coil form 54 by the conical extension 55.

The record sheet 66 is moved with respect to stylus 63 in synchronism with the transmitted picture |4 in order to properly compose the facsimile reproduction thereof. I have not illustrated synchronizing methods since they form no part of my present invention.

A second coil 10 is mounted on the coil form 54 and acts in the common air-gap of an electrodynamic unit together with coll 55. Coil 10 is connected to a potentiometer 1| in turn connected to the output of a local audio frequency oscillator 13. Field coil rheostat 59 and potentiometer 1| are adjusted with no facsimile signal input to units 55 so as to produce facsimile impulses upon record sheet 66 of predetermined intensity. The frequency of oscillator 13 is adjusted to a value dependent upon the half-tone effect desired. A higher local frequency will result in a greater number of impulses per unit area and resulting in a correspondingly darker half-tone representation for black picture reproductions.

The alternating current locally produced in the movable coil 10 reacts with the steady magnetic field in the air-gap of unit 55 to vibrate the stylus 63. When no signal current flows through coil 53 the marking impulses upon sheet 55 proceed at a predetermined frequency, for example 3000 cycles and produce a plurality of successive closely spaced dots corresponding to a black signal of the transmitted picture.

When a White picture signal is being transmitted, a corresponding facsimile signal will result in the direct current output of rectifier 55 flowing in coil 53. The polarity of direct current signal ow through coil 53 is connected so that the action of coil 53 is to decrease or buck the strength of the downward or marking impulse due to the local oscillating action by coil 10, to a degree sufficient to avoid an actual mark upon the record sheet 65. A corresponding white portion results upon the record sheet 55 during a signal-on condition. The dark picture section is a plurality of discrete dots or closely spaced marks. The facsimile signals are accordingly superimposed on a loca marking" circuit -to act as an interrupter of the local marking action. The translation efficiency of the reproducer is greatly increased by using the electromagnetic bucking action on local facsimile reproduction means of my present invention.

By converting marking stylus 55 to a sharp etching tool and record sheet 55 to a zinc plate,

a direct photo-engraving action results with a half-tone representation upon the plate avoiding intermediate photographic steps for newspaper plants.

Figure 3 represents a modification of the local energization facsimile reproduction system hereinabove represented by the electrodynamic unit 55 of Figure 2, wherein an electromechanical reproducing unit is employed. The receiver 45, antenna 4|, speaker 44, switch 45 and rectifier unit 50 are similar to the correspondingly numbered components of Figure 2. 'I'he output 5 |-52 of rectifier 55 is connected to solenoid 50 mounted on a common soft iron core 5| of the electromechanical reproducer 52. Another coil 55 is connected to a direct current source 55 through rheostat 55. The attraction for the amature 55 by the electromagnetic action of coil 55 on core 5| is adjustable by varying biasing currents by means of rheostat 55.

The local oscillator 15 passes alternating current of a predetermined frequency through the winding 54 on the core 5| of amplitude controllable potentiometer 1|.

The armature 55 is compliantly mounted on supporting post 55 by leaf spring 51. A spring 55 fixed at one end to member 55 mechanically biases the armature 55 away from the electromagnetic core 5|. A projection 55 in member 5S limits the upward excursion of the armature 85. A marker 5| is secured to receptacle 52 attached to one end of armature 55. A sheet 55 is mounted on drum 54 which is maintained in synchronism with the transmitter drum I5 in rder to correctly compose facsimile reproducion.

4The action of the local oscillator 15 is to cause a varying attraction on the amature 55 and to produce marking impulses of the stylus 5| on the sheet 93 at the predetermined frequency of the oscillator 15. As the sheet 55 moves with respect to the vibrating marking system, a succession of closely spaced marking dots or impulses are formed thereon. The strength of the marking impulses is adjusted by varying the direct current biasing action of coil 55 with rheostat 55 or by controlling potentiometer 1| of oscillator 15 or both. The rectifier facsimile signal current flowing through winding 55 is polarized so that it bucks the armature 55 attraction due to the local direct current biasing action of winding 55. When a "white facsimile signal occurs it will buck or react against the direct current biasing attraction upon armature 55 suilicient to result in a no marking action by the stylus 5| on sheet 55.

The maior portion of the reproducer energy is locally generated in accordance with the facsimile reproducers of my present invention. 'Ihe facsimile signals are utilized to differentially act upon the dot printing stylus of the reproducer mechanism to a degree merely sufiicient to avoid marking impressions by the stylus.

The marking energy of the stylus oscillating at a predetermined amplitude and frequency is supplied locally in amounts sufficient to produce the record markings or the metallic etching operations. 'Ihe signal impulses counteract to some degree the impression excursion of the 7 stylus and limit its excursion to prevent the marking actions.

I claim:

l. In a picture receiving system, a local source of alternating current; an electrodynamic recording unit comprising a movable unit containing a stylus, a first coil connected to said source for operating the stylus on a record sheet and a second coil responsive to incoming picture signals for rendering the operation of said stylus on said sheet' inefIectual by electromagnetically affecting the action of said first coil.

2. In a picture receiving system, a local. source of alternating current; means for rectifying picture signals; an electrodynamic recording unit comprising a stationary, substantially uniform magnetic field, a unit movable in said field containing a stylus, a iirst coil mounted on said unit within the magnetic field, said coil being connected to said source for operating the stylus on a record sheet and a second coil mounted on said unit responsive to the rectifiedpicture signals for preventing marking impulses of said stylus on said sheet by electromagnetically atfecting the action of said rst coil.

3. In a picture receiving system, a local source of alternating current; means for rectifying picture signals; an electrodynamic recording unit comprising a stationary, substantially uniform magnetic field, a unit movable in said ileld containing a stylus, a first coil mounted on said unit within the magnetic field, said coil being connected to said source for operating the stylus on a record sheet, a second coil mounted on said unit responsive to the rectified picture signals for preventing marking impulses of said stylus on said sheet by electromagnetically aiIecting the action of said first coil, and means for controlling the intensity of the marking impulses cornprising a potentiometer connected between said second coil and said source.

4. In a picture receiving system, a local source of alternating current; means for rectifylng picture signals comprising a copper-oxide rectifier; an electrodynamic recording unit comprising a stationary substantially uniform magnetic field, a unit movable in said field containing a stylus, a coil mounted on said unit within the magnetic ileld, said coil being connected to said source for operating the stylus on a record sheet at a predetermined frequency, a second coil vmounted on said unit responsive to the rectified picture signals for preventing marking im pulses of said stylus on said sheet by electromagnetically afIecting the action of said first coil and means for controlling the intensity of the marking impulses comprising a potentiometer connected between said second coil and said www.

5. In a picture receiving system, a local source of alternating current; a recording unit comprising a vibratory armature containing a stylus, a coil having a magnetic core in operative relation with said armature, said coil being connected to said source for operating the stylus on a record sheet at a predetermined frequency; and a second coil responsive to incoming picture signals for rendering the operation of said stylus on said'sheet ineffectual by electromagnetically aiTecting the action of the first coil.

6. In a picture receiving system, a local source of alternating current; means for rectifying picture signals comprising a copper-oxide rectier; an electromechanical recording unit comprising a vibratory armature containing a stylus, a coil having a magnetic core in operative relation with said armature, said coil being connected to said source for operating the stylus on a record sheet at a predetermined frequency. and a second coil responsive to the rectified picture signals for preventing marking impulses of said stylus on said sheet by electromagnetically affecting the action of the first coil.

7. In a picture receiving system, a local source of alternating current; means for rectifying picture signals; an electromechanical recording unit comprising an armature containing a stylus, a solenoid having a magnetic core in operative relation with said armature, said solenoid being connected to said source for operating the stylus on a record sheet and a second solenoid on said core responsive to the rectified picture signals for preventing marking impulses of said stylus on said sheet by electromagnetically affecting the action of the first solenoid.

8. In a picture receiving system, a local source of alternating current; means for rectifying picture signals comprising a copper-oxide rectier; an electromechanical recordingunit comprising a vibratory armature containing a stylus, a coil having a magnetic core in operative relation with said armature, said coil being connected to said source for operating the stylus on a record sheet at a predetermined frequency, a second coil on said core responsive to the rectified picture signals for preventing marking impulses of said stylus on said sheet by electromagnetically affecting the action of the rst coil and means for controlling the intensity oi' the marking impulses comprising a third coil on said core, a source of direct current and a rheostat connected in series.

WILLIAM G. H. FINCH.