US2247051A - Method and apparatus for television - Google Patents

Method and apparatus for television Download PDF

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US2247051A
US2247051A US272319A US27231938A US2247051A US 2247051 A US2247051 A US 2247051A US 272319 A US272319 A US 272319A US 27231938 A US27231938 A US 27231938A US 2247051 A US2247051 A US 2247051A
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electric
image
frequency
laminae
elements
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Chilowsky Constantin
Guerbilsky Alexis
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/07—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-optical liquids exhibiting Kerr effect
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical

Definitions

  • the piez'o-electric crystal having once been set in vibration does not return to rest for too long a time for the purposes of television. Attempts have been made to damp the oscillations of said crystal but this procedure has not been at all satisfactory because this damping can only be performed to the detriment of the acuteness and the intensity of the oscillation.
  • the present invention remedies these difiioulties and solves the problem on an entirely different principle.
  • the present invention is characterized by the production, at the same time as the variation of intensity in the electric current corresponding to the variations in the intensity of illumination at the various points of the image to be transmitted, of variations of frequency in said electric current, these variations corresponding at every moment to the position of the luminous spot being transmitted at that moment and doing this, moreover, even if the variations in position of said spot are very rapid.
  • the receiver it is possible by means of the variations of frequency in the electrical current received to determine the position of the luminous spot to be reproduced corresponding to the position of the spot transmitted and by means of the variations of electrical intensity of said current to determine the intensity of illumination of the spot reproduced.
  • the invention enables the following to be attained simultaneously:-
  • a certain frequency, or a combination of two or more frequencies, of the electrical current or currents which effect the transmission of the image is made to correspond to each element to be decomposed at the transmitter and recomposed at the receiver, so that the transmission of each element (or alternatively of each group of elements) is effected by a frequency proper to that element or to that group of elements, said frequency being reproduced periodically according to one or more continuous (or non-continuous) cycles of variations, and the period of this cycle or cycles of variation being, in general, less than the duration of the persistence of vision of the retina.
  • the transmission of the image is, generally speaking, effected by one or more waves of variable frequency having periodically values forming a continuous or discontinuous series or in other words, by one, or possibly several, bands of frequency.
  • this cyclically varying frequency sets in resonance oscillation a plurality of separate resonators or of resonators constituting one or more series, more or less continuous, of individual distinct frequencies lying within the limits which correspond to resonance with the extreme frequencies of transmission (or within their harmonics).
  • the fundamental frequencies for television are extremely high and are generally of the order of magnitude of frequencies employed in wireless telegraphy. It is to be expressly noted that the transmission of the image may be by Wire or by wireless transmission.
  • the resonators commencing resonance suc cessively in conformity with the variation in frequency of the transmission, elfect the creation or maintenance of the image or the variation in intensity of illumination producing reconstitution of said image.
  • the assembly .of said resonators is disposed or arranged in space in such a fashion as to produce the proper location of the luminous points on the screen for reproducing the image.
  • the resonators may be of various kinds but whatever they may be, their function is to maintain, create or modify luminous intensity when put into resonance by the electric currents or electro-magnetic oscillations.
  • the resonators may be of the following types:
  • Piezo-electric resonators effecting the establishment or the variation of the light by the modification of the optical paths traversed by the light in one or a plurality of piezoelectric crystals in a state of resonance.
  • Electro-mechanical resonators (piezo-electrio in particular) coming successively into Vibration and permitting a pre-determined movement to take place, thereby actuating optical devices such as revoluble or oscillating mirrors in such a manner as to throw at each instant a luminous beam in a different direction.
  • the piezo-electric resonator can b used (as) directly by the variations of its optical properties or (b) indirectly by the utilization of the mechanical effects which it is capable of producing.
  • One of the modes of using these mechanical effects constitutes a very important example of an embodiment of the invention.
  • the image is reconstituted by two distinct mechanisms each controlled by a separate band resonators suitably disposed and conveniently localizing the light.
  • Th displacement according to the second co-ordination is efiected by known synchronization means such as synchronous motors and the like.
  • the synchronous motor itself to be constituted by a large number of resonators, and piezo-electric devices in particular, successively controlled by a band of frequencies thereby providing a synchronous motor operative in accordance with the second co-ordination for displacing the luminous spot proceeding from the first group of resonators.
  • variable frequency of the transmitting station can also operate simultaneously upon the decomposing set and, at the receiving station, upon the set which reconstitutes the image.
  • These two sets or installations will comprise, for example, resonators (preferably piezo-electric devices) alike or coordinated in an appropriate manner. lhey effect in the decomposition, the successive projection of the elements of the image upon a photo-electric device which modulates an electric current in accordance with the luminosity of the successive elements received. At the receiving station, they effect the luminous reconstitution of the image.
  • a feature of the present invention is a method of transmitting images electrically which comprises establishing an oscillating current, decomposing the image to be, transmitted in elements through a scanning device, successively projecting the said elements so as to vary photoelectrically the intensity of the said current, and varying the frequency of the said current under control of the functioning of the said scanning device.
  • Another feature of the invention consistsin that the frequency of the oscillating current utilized for transmitting the elements of the image is varied in accordance with the variation in position of a movable member simultaneously actuated with the scanning device decomposing the image in elements.
  • Figure 1 is a diagram of a transmitting set for television.
  • Figure 2 is a diagram of a corresponding receiving set.
  • Figure 2a shows a detail of the Figure 2 in side elevation.
  • Figure 3 shows diagrammatically a modified detail of the receiving set.
  • Figure 4 shows a piezo-electric block in steps replacing a group of laminae.
  • Figure 5 shows a variant of Figure 2 in which are utilized two series of crossed piezo-electric elements.
  • a I p Figures 6 and 7 show two variations of Figure 5 in which a group of laminae is replaced by an oscillating mirror.
  • Figures 6a and 7a show respectively details of Figures 6 and tion.
  • Figures 8 and 9 show arrangements in which the piezo-electric elements operate at the reception station by regulating the speed of a motor.
  • Figure 1 illustrates the first mode of carrying the invention into effect in a transmitter.
  • the image I to be transmitted is projected by a lens Z upon a wheel B fitted around its periphery with mirrors m.
  • the inclination of the mirrors to the plane of the figure is variable so that in the rotation of the Wheel bearing the mirrors all points of the image I aresuccessively projected by the mirrors m and the lens Z2 to an aperture f behind which a photo-electric cell c or some other photo-sensitive element.
  • This employment of a irror-carrying wheel as a scanning device is already known. 1
  • the wheel R determines the variation, either continuous or discontinuous, of a variable capacity C, or of some other electric device such as an inductance, such capacity or other device being connected in the transmission circuit so that the frequency employed in such transmission depends upon it.
  • a corresponding frequency is determined for the transmission.
  • wheel B may be geared with the spindle of a suitable variable condenser or it may carry plates connected with the transmission circuit and making contact successively with the brush terminals of different condensers.
  • the currents which traverse the photo-electric cell c, after amplification in the amplifier a act upon the transmitting circuit through the medium of the inductance i for modulating the intensity of transmission.
  • the transmission cir-' cult is illustrated very diagrammatically in Fig-' ure 1, and it is understood that it could be replaced by any other oscillatory circuit.
  • This circuit operates through the medium of the amplifier a2 upon the transmitting antenna 2.
  • the emissions from this transmitting station are of a frequency which varies according to the position of the elements explored by the wheel and of an intensity which varies with the brightness or luminosity of that element.
  • the receiving set as shown in Fig. 2 comprises primarily a field of light polarized and parallel or almost parallel and provided by a source of light 8, a condenser lens L, an aperture 0 upon which forms the image of the source S.
  • This image placed at the focus of the lens L2 gives a pencil of parallel rays traversing a polarizer P.
  • a pile of laminae of piezo-electriccrystals interposed between armatures in such manner as to constitute an arrangement of condensers.
  • Each lamina of piezo-electric crystal is placed in the path of the bundle of luminous rays bounding an element of the image. It has been explained that for each element of the image there is a corresponding emission frequency. Consequently the laminae of piezo-electric crystal will be constructed in such a manner that each lamina has an appropriate frequency of vibration and that such lamina resonates when it is excited by an alternating electrostatic field having a frequency corresponding to that element of the image to which the lamina itself corresponds.
  • the polarized light after having traversed the 7 in side eleva
  • the U laminae Q passes through the compensator Q constituted for example, by laminae of the same crystal of the same length or thickness (according to whether the light traverses the piezo-electric laminae in the direction of their length or in the directon of ther thickness).
  • the slow and rapid axes of these crystal laminae of the compensator Q are-displaced through with relation to the similar axes of the laminae Q in such manner as to bring about, in known manner, the compensatory effect on the luminous rays.
  • an analyzer A arranged in such a manner as to obtain an extinction when all the laminae are in repose.
  • the rays are projected by the lens L upon a screen Z.
  • the circuits 5 and 6 have resonance curves (intensity as a function of or plotted against frequency) differing from the resonance curve of the circuit t and the three circuits are chosen, for example, in such manner that the bands of increasing frequencies for which they are respectively in resonance overlap slightly. It will be clear that with such an association of circuits, it-is then possible to cause the piezo-electric laminae to Vibrate between much greater frequency limits.
  • the three cincuits t, 5 and 6, instead of being coupled with one and the same inductance 3 can be associated, for example, with three distinct circuits each comprising a tier of piezo-electric laminae Q. Three circuits l, 5 and 6 have been illustrated but it is possible to use two or a greater number than three.
  • the wheel R projects the luminous rays and an element of the image upon the photo-electric cell a corresponding crystal lamina at the receiving station is put into vibration and produces light at the exit of the analyser, with amplitudes which are greater as the intensity of transmitting current and consequently the mean light of the element are greater.
  • the plurality of piezo-electric laminae can be replaced by one or more piezo electric laminae the thickness of which varies from point to point or from place to place, the dimensions of the places corresponding with those of the decomposition elements of the image. This variation in thickness is sufficient, in effect, to'create variations in resonance.
  • the electrical axis of the lamina assuming it to be sufliciently thin, preferably coincides with the direction of the light.
  • Fig. l One way of producing such a device is illustrated in Fig. l, wherein the said device is formed of a series of prisms H], II, l2, I3, 14, the lower faces of such prisms being in the same plane E6.
  • the upper face I5 of the prism I is inclined to the plane 16 in such manner that the edge ll is nearer to the plane 16 than the edge [8.
  • the edge I9 is at the same distance from the plane l6 as the edge ll but the edge 20 is nearer to the plane l6, and
  • One important modification of the receiving installation consists inreplacing the multitude of piezoelectric laminae by an arrangement comprising two piezo-electric plates or blades 3
  • the functioning of each of the blades or plates 3 l, 32' is analogous to that of each of the steps in Fig.
  • the two blades or plates 3! and 32 are disposed at 90 one with reference to the other, i. e. their trapezoidal crosssections are respectively in the plane of the figure and in a plane perpendicular thereto, the said cross-section being of course in each case perpendicular to the axis of the light beam to be modulated; consequently each element 3
  • the luminous point provided by the intersection of the two allowed passages for the light will thus correspond to the frequency determined by the coordinates of the corresponding point of the picture, as transmitted through the two circuits 31, 38.
  • a motor enabling the mirror to be rotated with a sufficiently high degree of precision (that is to say in very close synchronization with the transmission).
  • This motor may be constructed in the manner which will be described below.
  • a paddle member 59 fixed to a shaft 5! is driven continuously to rotate in the direction of the arrow by an appropriate mechanical or electro-mechanical arrangement, for example, a rotary field arrangement.
  • an appropriate mechanical or electro-mechanical arrangement for example, a rotary field arrangement.
  • the piezo-electric laminae 52, 52', 52" preferably of quartz on account of the mechanical qualities and the sensitiveness of the crystal.
  • the laminae enter into vibration one after the other at precise instants due to the fact that they are disposed in a receiving circuit for the electrical waves in the manner of the laminae Q of Fig. 2 and if, for example, laminae of quartz are provided and the complete cycle of variations of frequency at the transmitting station is effected in A of a second, then the laminae 52, 52 commence to receive vibrations successively at of a second intervals and thus correct the precision of the paddle movement in such a manner that the advance or retardation at any instant may not exceed of a revolution, say of a second and in practice will always be considerably less than this amount.
  • the piezo-electric resonators are constituted in this case preferably in such a manner that their electrical axes are directed according to their thickness that is to say perpendicularly to the useful elongations of the laminae.
  • Fig. 9 illustrates a variant of the method, the quartz laminae being, for purposes of explanation, considered to be numbered in order. If all the even laminae are vibrated at one and the same frequency and the odd laminae are vibrated at another frequency, the paddle 5!! being replaced in this variant by the disc 53 carrying teeth of an appropriate profile and the spacing or pitch of which corresponds to that of two laminae vibrating at the same frequency, all the laminae of similar frequency are vibrating simultaneously and. the braking and controlling efiort is multiplied by the number of laminae vibrating simultaneously.
  • Fig. 6 illustrates the application of this motor to the carrying out of the method of recomposition of the image in which a group of piezo-electric laminae and the motor are employed.
  • a bundle of rays traverses the polarizer P, the piezo-electric prism 34, the optical compensator 3-3, the analyser A, a cylindrical lens I which transforms the luminous bands transmitted by the prism 3! into points, and an objective Z which concentrates all these points upon the mirror m oscillating about an axis 55 perpendicularto the edge of the prism 31.
  • the oscillation of the mirror is produced by means of the motor described with reference to Fig. 8 or Fig. 9, but which can be replaced by another appropriate motor such as a high frequency synchronous motor, and also by means of a mechanism such as an eccentric 55, crank and connecting rod, or any other appropriate cinematic mechanism.
  • the light is then projected by an objective Z" upon the screen 6.
  • the mirror m projects the light coming from the analyser according to difierent bands of the screen.
  • the local resonances of the prism. 3!, or the resonant elements of an assemblage of piezoelectric elements, by which the prism may be replaced, as will be seen farther on, determine at each instant a luminous point of these lines.
  • the position of the mirror and the place of local resonance of the prism, or of the resonant piezo-electric element determines with the two co-ordinates the luminous point of the image.
  • This arrangement shows how it is possible, in general, to have an electric field disposed according to the direction or" the light without preventing the light irom passing.
  • the prism 3! can be replaced by a series of superposed laminae, 100 for example, of different lengths varying between the same limits as the thicknesses of the prism.
  • the receiver it is also possible in the receiver to combine several resonators for obtaining the variation of one of the co-ordinates in such a manner as zone X, the second time upon the zone Y and the third time upon the zone Z.
  • optical devices are disposed between the elements U and the screen and such devices project the light coming from U upon the three zones X, Y and Z.
  • an electro-optic relay as for example a piezo-electric resonator inserted between a polarizer and an analyser, controlled in such a manner that the light at any given instant can pass to a single one only of these three zones according to the fraction of the picture which is being transmitted at thisvv moment.
  • electro-optic relays are actuated either by a current from the transmitting station or by a current which is established or cut ofi each time that the series of resonators U has been traversed by a complete cycle of frequencies. It is possible for this purpose to make use of basculators of a known type, as for example thermionic tubes mounted in a special manner.
  • piezo-electric crystals notably quartz, Rochelle salt, and tourmaline.
  • Rochelle salt is very sensitive, quartz is sensitive and robust, and is also very bi-reiracting.
  • quartz is sensitive and robust, and is also very bi-reiracting.
  • One of these two crystals would usually be selected but the others could also be employed.
  • piezo-electric crystals are not indispensable and these crystals at the receiving station may be replaced by a rarefied gas bulb (a neon bulb for example), the wall of which is interiorly metallized while being transparent to the light.
  • a rarefied gas bulb a neon bulb for example
  • the single bulb or tube may be replaced by a plurality of lamps adapted for giving luminous discharges in rarefied gas, and in particular neon lamps.
  • resonant electric circuits which can be furnished with piezo-electric frequency stabilizers, constituting a series of frequencies appropriate and distinct, these circuits being actuated in their order by the periodic variation of frequency of reception current.
  • monochromatic light may be made use of.
  • the crystalline thickness traversed by the polarized light would be calculated so that they are James ondes or lames demi-ondes for the radiation selected.
  • photo-electric cells have been referred to, but it is to be understood that it is possible to replace these cells by other devices capable of translating luminous intensity variations (or variations of radiations other than light) into variations of electric current, or into variations of fields either electric or mag-
  • other devices capable of translating luminous intensity variations (or variations of radiations other than light) into variations of electric current, or into variations of fields either electric or mag-
  • selenium cells, or ionization chambers for the ultra-violet
  • a luminously responsive receiving screen comprising a plurality of electrical conductors associated with a body of inert gas, said conductors being arranged in a plurality of parallel planes corresponding in number and arrangement to the different lines described across the transmitted picture, means for making said conductors luminous, and means for causing each point of a conductor to glow with the proper intensity to reproduce a picture point.
  • a television system comprising means for transmitting variable frequency signals, means for receiving variable frequency signals, and a screen for visually reproducing the variable frequency signals comprising a multiplicity of parallel extending luminous portions electrically connected to each other and with said receiving means, means for making said portions luminous, and means for causing each point of a luminous portion to glow with the proper intensity to reproduce a picture point.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, nonelectric movable means for causing said photoelectric means to be illuminated with successive luminous intensities corresponding respectively with the luminous intensities of all the elements of the image to be transmitted, movable means distinct from said photo-electric means for varying the frequency of electromagnetic waves thus produced, means for simultaneously actuating both of these movable means, and receiving means responsive to said electromagnetic waves for reproducing said decomposed image.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of said electro-magnetic waves, non-electric movable means for causing said photo-electric means to be illuminated with successive luminous intensities corresponding respectively with the luminous intensities of all the elements of the image to be transmitted, movable means distinct from said photo-electric means for varying the frequency of said electro-magnetic waves, means for simultaneously actuating both of said movable means, and receiving means responsive to said electromagnetic waves for reproducing said decomposed image.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, movable optical scanning means for successively projecting all the elements of the image to be transmitted onto said photo-electric means, movable means distinct from said photo-electric means for varying the frequency of electromagnetic waves thus produced, means for simultaneously actuating both of said movable means, and receiving means responsive to said electro-magnetic waves for reproducing the image.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of said electromagnetic waves, movable optical scanning means for successively projecting all the elements of the image to be transmitted onto said photo-electric means, movable means distinct from said photo-electric means for varying the frequency of said electromagnetic waves, means for simultaneously actuating both of said movable means, and receiving means responsive to said electro-magnetic waves for reproducing the decomposed image.
  • a system for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, non-electric movable means for causing said photo-electric means to be illuminated with successive luminous intensities corresponding respectively with the luminous intensities of all the elements of the image to be transmitted, movable means distinct from said photo-electric means, for varying the frequency of electromagnetic waves thus produced, means for simultaneously actuating both of said movable means, and a receiving device including, a source of light, a plurality of optical effect producing resonators adapted to coact with said source of light for establishing one of the coordinates of the elements of the image to be tarnsmitted, a movable optical system adapted to coact with said source of light for establishing the other coordinate of these elements of the image, a motor for driving said optical system at a predetermined speed, electrical receiving means responsive to electromagnetic waves of varying frequency for imparting vibrations to said resonators, and means responsive to electromagnetic waves of varying ampli
  • a system for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, non-electric movable means for causing said photo-electric means to be illuminated with successive luminous intensities corresponding respectively with the luminous intensities of all the elements of the image to be transmitted, movable means distinct from said photoelectric means, for varying the frequency of the electromagnetic waves thus produced, means for simultaneously actuating both of said movable means, and a receiving device including, a source of light, a plurality of optical effect producing resonators adapted to coact with said source of light for establishing one of the coordinates of the elements of the image to be transmitted, a movable optical system adapted to coact with said source of light for establishing the other coordinate of these elements of the image, a motor for driving said optical system at a predetermined speed, electrical receiving means responsive to electromagnetic waves of varying frequency for imparting vibrations to said resonators, and means responsive to electromagnetic waves of varying amplitude for directly
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, nonelectric movable means for causing said photo electric means to be illuminated with successive luminous intensities corresponding respectively with the luminous intensities of the elements of the image to be transmitted, movable means distinct from said photoelectric means, for varying the frequency of electromagnetic waves thus produced, and means for simultaneously actuating both of these movable means.
  • An apparatus for the electrical transmission of imag s which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of said electromagnetic waves, non-electric movable means for causing said photo-electric means to be illuminated with successive luminous intensities corresponding respectively with the 111- minous intensities of all the elements of the image to be transmitted, movable means distinct from said photo-electric means for varying the frequency of said electromagnetic waves, and means for simultaneously actuating both of said movable means.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of electromagnetic waves thus produced, movable optical scanning means for successively projecting all the elements of the image to be transmitted onto said photo-electric means, movable means distinct from said photoelectric means for varying the frequency of electromagnetic waves thus produced, and means for simultaneously actuating both of these movable means.
  • An apparatus for the electrical transmission of images which comprises in combination, means for producing electromagnetic waves, photo-electric means for varying the amplitude of said electromagnetic waves, movable optical scanning means for successively projecting all the elements of the image to be transmitted onto said photo-electric means, movable means distinct from said photo-electric means for varying the, frequency of said electromagnetic waves, and means for simultaneously actuating both of said movable means.
  • a plurality of piezoelectric elements and means for exciting said elements in succession periodically to resonate with amplitudes corresponding respectively to tone values of elemental areas of said field of view
  • said means including a means for applying a high frequency field across the crystal in a direction such that each vector of said field passes only through a single crystal element.
  • a piezo-electric crystal having a pair of opposite faces non-uniformly spaced at different points throughout their area, said crystal being adapted to vibrate for a band of frequencies corresponding to the dimensions of the crystal between said non-uniformly spaced points, and means to apply a high frequency field across the crystal in a direction such that each vector of said field passes only through the portions of the crystal belonging to a single resonant element.
  • a piezo-electric crystal having a pair of opposite faces tapered toward each other, said crystal being adapted to vibrate for a band of frequencies corresponding to the dimensions of the crystal between its tapering faces, and means to apply a high frequency field across the crystal in a direction such that each vector of said field passes only through the portions of the crystal belonging to a single resonant element.
  • a piezo-electric crystal having a pair of opposite faces non-uniformly spaced at different points throughout their area, said crystal being adapted to vibrate for a band of frequencies corresponding to the dimensions of the crystal between said non-uniformly spaced points, and means to apply a high frequency field across the crystal in a direction such that each vector of said field passes only through the portions of the crystal belonging to a single resonant element, at least one of said faces being step-shaped.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
US272319A 1927-04-26 1938-04-23 Method and apparatus for television Expired - Lifetime US2247051A (en)

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US (1) US2247051A (forum.php)
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DE (2) DE538297C (forum.php)
FR (1) FR644240A (forum.php)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2766659A (en) * 1950-12-11 1956-10-16 Clevite Corp Device for controlling light intensity
US3145355A (en) * 1961-09-20 1964-08-18 Lab For Electronics Inc Variable ultrasonic delay line
US3235799A (en) * 1954-12-27 1966-02-15 Hurvitz Hyman Electroluminescent frequency sensitive visual indicator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE865004C (de) * 1937-08-25 1953-01-29 Interessengemeinschaft Fuer Ru Anordnung zur Wiedergabe eines Fernsehbildes, dessen einzelne Elemente je auf verschiedenen Traegerwellen uebertragen werden
DE877621C (de) * 1938-10-20 1953-05-26 Interessengemeinschaft Fuer Ru Verfahren zur UEbertragung bewegter Bilder
US2591701A (en) * 1947-10-15 1952-04-08 Brush Dev Co Electrical light-transmission controlling arrangement

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2766659A (en) * 1950-12-11 1956-10-16 Clevite Corp Device for controlling light intensity
US3235799A (en) * 1954-12-27 1966-02-15 Hurvitz Hyman Electroluminescent frequency sensitive visual indicator
US3145355A (en) * 1961-09-20 1964-08-18 Lab For Electronics Inc Variable ultrasonic delay line

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GB289416A (en) 1929-07-04
BE350608A (forum.php)
DE599442C (de) 1934-07-02
DE538297C (de) 1931-11-12
FR644240A (fr) 1928-10-04

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