US2163215A - Television transmitter - Google Patents

Television transmitter Download PDF

Info

Publication number
US2163215A
US2163215A US14846A US1484635A US2163215A US 2163215 A US2163215 A US 2163215A US 14846 A US14846 A US 14846A US 1484635 A US1484635 A US 1484635A US 2163215 A US2163215 A US 2163215A
Authority
US
United States
Prior art keywords
signals
potential
resistance
picture
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US14846A
Inventor
Schlesinger Kurt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Loewe Opta GmbH
Original Assignee
Loewe Opta GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Loewe Opta GmbH filed Critical Loewe Opta GmbH
Application granted granted Critical
Publication of US2163215A publication Critical patent/US2163215A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/1607—Supply circuits
    • H04B1/1623—Supply circuits using tubes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/06—Generation of synchronising signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/06—Generation of synchronising signals
    • H04N5/067—Arrangements or circuits at the transmitter end
    • H04N5/0675—Arrangements or circuits at the transmitter end for mixing the synchronising signals with the picture signal or mutually
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/08—Separation of synchronising signals from picture signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/38—Transmitter circuitry for the transmission of television signals according to analogue transmission standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/52—Automatic gain control

Definitions

  • the present invention relates to television transmitters which, on the same wave with the video signals, transmits synchronisation impulses.
  • synchronisation impulses As Wellknown, it is necessary in transmitters of this ⁇ kind that the synchronisation impulses exceed toa certain extent the highest amplitudes ofthe video current, so that at the receiver a proper separation of synchronisation and video signals by means of an amplitude filter will be possible.
  • VAccording to the invention the correct amplitude ratio of video and synchronizing signals is already ensured on the low frequency side, i. e. prior to the entry of the modulating potentials into thehigh-.frequency transmitter. It has already 'been shown in the application Ser. No. 725,743 in what manner a .low-frequency mixing of the image signals and the synchronisation signals ⁇ in this way may be brought about, for example by producing the synchronisation signals electrically .by means of a special impulse connectionand performing an electrical mixing at the output of vthe image current amplifier.
  • the present application sets forth a special method in order to prevent the image potential peaks from becoming occasionally equal to or greater than the synchronisation peaks.
  • the application accordingly relates to the combination of amplitude lirnitingimeans operating without inertia for the image .current amplifier with the method previously set forth in the application Ser. No. 712,971 for the low-frequency mixing of synchronisation and image signals.
  • FIG. 1 shows the general scheme of a transmitteraccorcling to the invention
  • FIG. 2 shows a more detailed connection diagram
  • Fig. 1 shows by way of example a transmission arrangement with low-frequency mixing.
  • the Nipkow disc of the transmitter whiohscans the image in the known fashion and controls the image current amplier 3 through the medium of a-.photo-cell 2, ywhilst a second photo-Celli behind-a separate ring of apertures receives the line frequency.
  • the latter is passed to a special impulse apparatus 5 which, as already described in detail in the application No,
  • the invention will be more clearly explained 725,743, and the construction of which is moreover not essential for comprehension of the present application, furnishes the lead 6 with signals of constant amplitude (for example 30 volts), constant direction (preferably negative, i. e. in the image black) and constant duration (for example 5% of the line period),
  • the two outputs i. e. the leads 6 and 1, the latter being the output of the video current amplifier 3, are connected to the input of a common vhigh frequency transmitter 8. If the unmodulated aerial current is equal to half the maximum value the controlling voltage furnished by the amplifier 3 must obviously full the following conditions:
  • the device referred to under l should be capable of being adjusted and of operating independently of the devices referred to under 2 and 3.
  • Fig. 2 shows a form of embodiment of the peak value device according to the invention.
  • a penultimate and a final amplifier tube 9 and I0 coupled by means of anode resistance I5 and condenser'l.
  • Negative signals at the amplifier output 'I indicate positive signs at the grid of thenal amplier tube Iii.
  • a potential limiter consisting of a discharge tube I4, the anode of which is supplied with an adjustable bias of negative sign I3 over a series resistance I2.
  • the tube I4 is preferably a gaslled diodeV with small inner resistance, i.
  • a time constant of approximately 10-2 seconds is desirable which is obtained by choosing 11 to .1 mf. and 12 to about .1 megohm.
  • this peak value regulator regulates only the opposite amplitude of the signals not already limited by the tube I4.
  • a regulating tube of this character, operating a directional amplier, is designated I1, its anode potential source I8, its anode resistance I9, its grid bias regulator 22. From the point 20 a regulating lead passes to the grid of the tube 9.
  • the grid of the tube I1 is connected with Ya point, the potential of which has a phase of displacement of towards point I6, preferably by Way of the condenser 2I with the output lead 1.
  • this connection system there is not only obtained an adjustment of the amplier 3, regulable by the potentiometer 22, to an always constant medium output potential, but at the same time there is avoided an over-control into positive.
  • the requirements 2 and 3 are accordingly fullled.
  • a limiting device comprising a gas-lled discharge tube having anode and cathode, a D. C.
  • saidanode of said discharge tube being connected by means of said condenser to the input of one of said amplifier valves of said picturecurrent aniplier, said D. C. potential source and said resistance connected in series across the discharge space oi said discharge tube, said D. C. potential source being so adjusted as to limit the output potential of said picture current amplifier asV not to exceed a pre-determined value below the constant output potential of said synchronising signal amplifier.
  • a television transmission arrangement comprising means for transforming the picture to be transmitted into picture contents currents, means for generating synchronisation signals having a constant amplitude exceeding the great- ,est amplitude of said picture contents currents,
  • said electronic amplifiers containing a plurality of electronic valves, means for coupling the stages of said electronic amplier with one another, means for mixing the output potentials of said two amplifiers, means for generating an ultra-short carrier wave and means for modulating said mixture onto said ultra-short carrier wave, a limiting device comprising a gas-bookd discharge tube having anode and cathode, a D. C. potential source, resistance and a condenser, said anode of said discharge tube being connected by means of said condenser to the input ofone of said ampliervalves of said picture current ampliiier, said D. C.
  • said D. C. potential source being so adjusted as to limit the ouput potential of said picture current amplier as not to exceed a pre-determined value below the constant output potential of said synchronising signal amplier, and a regulating device connected to the output of said picture curret amplier for regulating the amplication degree of said picture current amplifier as to give a iixed potential range-for the khighest and lowest amplitudes of the output potential of said picture current ⁇ ampliiier.
  • a television transmission arrangement comprising means for transforming the picture to be transmitted into picture contents currents.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Amplifiers (AREA)
  • Picture Signal Circuits (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Television Systems (AREA)
  • Synchronizing For Television (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)

Description

June .20, 1939 K. scHLl-:slNGER 2,153,215
TELEVISION TRANSMITTER Filed April 5, 1935 v AMA Patented June 20, 1939 UNITED STATI-:s
TELEVISION TRANSMITTER Kurt Schlesinger, Berlin, Germany, assignor to Radioaktiengesellschaft D. S. Loewe, 'Berlin- Steglitz, Germany Application April 5,
1935, Serial No. 14,846
In Germany April 6, 1934 3 Claims.
The present invention relates to television transmitters which, on the same wave with the video signals, transmits synchronisation impulses. As Wellknown, it is necessary in transmitters of this `kind that the synchronisation impulses exceed toa certain extent the highest amplitudes ofthe video current, so that at the receiver a proper separation of synchronisation and video signals by means of an amplitude filter will be possible.
. It-has been proposed to ensure the said condition on .the high frequency side of the transmitter by modulating e. g. the antenna current by the video signals so that it never decreases under a certain minimum value. The aerial. current disappears entirely only when the aerial is disconnected from Vthe high frequency generator by a switch operated by the synchronisation signals, the requirement that thesesignals possess an overwhelming amplitude as compared with' the image` signals thus being complied with.
VAccording to the invention the correct amplitude ratio of video and synchronizing signals is already ensured on the low frequency side, i. e. prior to the entry of the modulating potentials into thehigh-.frequency transmitter. It has already 'been shown in the application Ser. No. 725,743 in what manner a .low-frequency mixing of the image signals and the synchronisation signals `in this way may be brought about, for example by producing the synchronisation signals electrically .by means of a special impulse connectionand performing an electrical mixing at the output of vthe image current amplifier. The present application sets forth a special method in order to prevent the image potential peaks from becoming occasionally equal to or greater than the synchronisation peaks. The application accordingly relates to the combination of amplitude lirnitingimeans operating without inertia for the image .current amplifier with the method previously set forth in the application Ser. No. 712,971 for the low-frequency mixing of synchronisation and image signals.
by means of the accompanying drawing, in which Fig. 1 shows the general scheme of a transmitteraccorcling to the invention, whilst Fig. 2 shows a more detailed connection diagram.
Fig. 1 shows by way of example a transmission arrangement with low-frequency mixing. In the same I is the Nipkow disc of the transmitter, whiohscans the image in the known fashion and controls the image current amplier 3 through the medium of a-.photo-cell 2, ywhilst a second photo-Celli behind-a separate ring of apertures receives the line frequency. The latter is passed to a special impulse apparatus 5 which, as already described in detail in the application No,
,The invention will be more clearly explained 725,743, and the construction of which is moreover not essential for comprehension of the present application, furnishes the lead 6 with signals of constant amplitude (for example 30 volts), constant direction (preferably negative, i. e. in the image black) and constant duration (for example 5% of the line period), The two outputs, i. e. the leads 6 and 1, the latter being the output of the video current amplifier 3, are connected to the input of a common vhigh frequency transmitter 8. If the unmodulated aerial current is equal to half the maximum value the controlling voltage furnished by the amplifier 3 must obviously full the following conditions:
1. In the negative direction it should never surpass a certain value lowering the antenna current to say 20% of its maximum amplitude. If .it exceeds this amount, the amplitude lter of the receiver is no longer able to perform a reliable separation of the signals, and the synchronism is instantly destroyed.
2. In the positive directionit should not surmount the control range of the transmitter.
3. When employing films withrapidly varying transparency there should be provided a special regulating device which compensates electrically the variable light conditions, modulating or strengthening Ythe contrasts of the image.
4. The device referred to under l should be capable of being adjusted and of operating independently of the devices referred to under 2 and 3.
Fig. 2 shows a form of embodiment of the peak value device according to the invention. In the train of the low frequency amplifier 3 there are shown a penultimate and a final amplifier tube 9 and I0 coupled by means of anode resistance I5 and condenser'l. Negative signals at the amplifier output 'I indicate positive signs at the grid of thenal amplier tube Iii. At this point, in accordance with the invention, there is connected through the medium of a coupling condenser II a potential limiter consisting of a discharge tube I4, the anode of which is supplied with an adjustable bias of negative sign I3 over a series resistance I2. The tube I4 is preferably a gaslled diodeV with small inner resistance, i. e., with high emission and small inner spacing. When the vpotential of the grid of the tube IIJ surpasses that of I3 the emission of I4 accordingly occurs very suddenly. The limiting eifect of the arrangement is improved by a series resistance 23. 23 should be small as compared with the capacitative input resistance of the tube I Il at the maximum image frequency, but large as compared with the discharge resistance of the tube I4. The signals, therefore, at the amplifier output 'I are unable to proceed beyond a negative surge value, the height of which may be adjusted by adjustment of the bias I3.
As regards the dimensioning of the coupling means II-I2 a time constant of approximately 10-2 seconds is desirable which is obtained by choosing 11 to .1 mf. and 12 to about .1 megohm.
The latter resistance is relatively large in com-1.
parison to the anode resistance I5 of approximately 5000 ohms. y Y j It is not suiiicient to ensure that the negative peak values are constant if at the same time the` degree of amplification of 3 has been incorrectly adjusted. If the amplifier is set to be too sensitive, it may occur for example that its output Yoscillation is already cut off proceeding from the centre. All values below the middle grey down to black would be made equal in the image, so that corresponding contours would not be visible at all. .The applicant has already set forth in the application No. 725,743 that upon the transmission care requires to be taken by means of an automatic regulator that the frequently occurring considerable fluctuations in the transparency of the lm and the copying brilliancy are intercepted. In addition to these conditions it is necessary that this peak value regulator regulates only the opposite amplitude of the signals not already limited by the tube I4. A regulating tube of this character, operating a directional amplier, is designated I1, its anode potential source I8, its anode resistance I9, its grid bias regulator 22. From the point 20 a regulating lead passes to the grid of the tube 9. The grid of the tube I1 is connected with Ya point, the potential of which has a phase of displacement of towards point I6, preferably by Way of the condenser 2I with the output lead 1. In this connection system there is not only obtained an adjustment of the amplier 3, regulable by the potentiometer 22, to an always constant medium output potential, but at the same time there is avoided an over-control into positive. The requirements 2 and 3 are accordingly fullled.
I claim:
l. In a television transmission arrangement comprising means for transforming the Vpicture vto be transmitted into picture contents currents,
means for generating synchronisation signals having a constant amplitude exceeding the greatest amplitude of said picture contents currents, two electronic ampliers for amplifying said picture contents currents and said synchronisation signals, said electronic amplifiers containing a plurality of electronic valves, means for coupling the stages of said electronic amplier with one another, means for mixing the output potentials of said two amplifiers, means for generating an ultra-short carrier wave and means for modulating said mixture onto said ultra-short carrier wave, a limiting device comprising a gas-lled discharge tube having anode and cathode, a D. C.
potential source, a resistance and a condenser,
saidanode of said discharge tube being connected by means of said condenser to the input of one of said amplifier valves of said picturecurrent aniplier, said D. C. potential source and said resistance connected in series across the discharge space oi said discharge tube, said D. C. potential source being so adjusted as to limit the output potential of said picture current amplifier asV not to exceed a pre-determined value below the constant output potential of said synchronising signal amplifier.
2. In a television transmission arrangement comprising means for transforming the picture to be transmitted into picture contents currents, means for generating synchronisation signals having a constant amplitude exceeding the great- ,est amplitude of said picture contents currents,
two electronic ampliers for amplifying said pic- 'j turecontents currents and said synchronisation signals, said electronic amplifiers containing a plurality of electronic valves, means for coupling the stages of said electronic amplier with one another, means for mixing the output potentials of said two amplifiers, means for generating an ultra-short carrier wave and means for modulating said mixture onto said ultra-short carrier wave, a limiting device comprising a gas-iiled discharge tube having anode and cathode, a D. C. potential source, resistance and a condenser, said anode of said discharge tube being connected by means of said condenser to the input ofone of said ampliervalves of said picture current ampliiier, said D. C. potential source and said resistance connected in series across the discharge space of said discharge tube, said D. C. potential source being so adjusted as to limit the ouput potential of said picture current amplier as not to exceed a pre-determined value below the constant output potential of said synchronising signal amplier, and a regulating device connected to the output of said picture curret amplier for regulating the amplication degree of said picture current amplifier as to give a iixed potential range-for the khighest and lowest amplitudes of the output potential of said picture current` ampliiier. l
1 3. In a television transmission arrangement comprising means for transforming the picture to be transmitted into picture contents currents. means for generating synchronisation signals having a constant amplitude exceeding the greatest amplitude of said picture contents currents, two electronicampliers for amplifying said picture contents currents andsaid synchronisation signals, said electronic ampliers containing a plurality of electronic valves, means for coupling the stages of said electronic ampliler with one another, .means for mixingthe output potentials of said two amplifiers, means for generating an ultra-short carrier wave and means for modulating said mixture onto said ultra-short carrier wave, a limiting device comprising a gas-illled discharge tube having anode and cathode, a D. C. potential source, resistance and a condenser, said anode of said dischargetube being connected by means Yof said condenser to the input of one of said amplifier valves of said picture current ampliiier, said D.'C. potential source and said resistance connected in series across the discharge space of said discharge tube, said D. C. potential source being so adjusted as to limit the output .the potential of said picture current amplier as not to exceed a pre-determined value below Ythe constant output potential of said synchronissaid limiting device independent of an adjust- 70,
ment of saidv regulating device.
' Y l KURT SCHLESINGER...
US14846A 1933-10-11 1935-04-05 Television transmitter Expired - Lifetime US2163215A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE445428X 1933-10-11
DE2226992X 1933-12-06
DE2163215X 1934-04-06

Publications (1)

Publication Number Publication Date
US2163215A true US2163215A (en) 1939-06-20

Family

ID=32073686

Family Applications (2)

Application Number Title Priority Date Filing Date
US756125A Expired - Lifetime US2226992A (en) 1933-10-11 1934-12-05 Picture receiving system
US14846A Expired - Lifetime US2163215A (en) 1933-10-11 1935-04-05 Television transmitter

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US756125A Expired - Lifetime US2226992A (en) 1933-10-11 1934-12-05 Picture receiving system

Country Status (5)

Country Link
US (2) US2226992A (en)
BE (3) BE405608A (en)
FR (6) FR773649A (en)
GB (6) GB441761A (en)
NL (3) NL45395C (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532799A (en) * 1944-08-01 1950-12-05 Rca Corp Facsimile system having rotating scanner moving longitudinally within stationary transparent drum

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2254204A (en) * 1936-05-15 1941-09-02 Emi Ltd Television system
DE741786C (en) * 1936-07-17 1943-11-17 Opta Radio Ag Television scanning arrangement in which the light beam scanning the image is also used to generate synchronizing characters
DE755948C (en) * 1937-01-09 1955-07-28 Opta Radio A G Amplitude filter circuit for the separation of picture content signals and synchronization characters in television
DE757397C (en) * 1937-03-18 1952-12-01 Emi Ltd Circuit for separating parts of a voltage curve that fluctuates over time
DE882252C (en) * 1938-11-10 1953-07-06 Telefunken Gmbh Circuit for the decrease of the control voltages for the line and line extension deflection in television receivers
DE742435C (en) * 1938-12-25 1943-12-03 Fernseh Gmbh Arrangement for separating the line and picture change pulses of the same amplitude, but different duration and frequency, when watching television
NL74227C (en) * 1948-09-11
AU3412095A (en) 1994-08-26 1996-03-22 Kensington Microware Limited Security device for a portable computer
US6662602B1 (en) 1996-11-08 2003-12-16 Acco Brands, Inc. Security device for a portable computer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532799A (en) * 1944-08-01 1950-12-05 Rca Corp Facsimile system having rotating scanner moving longitudinally within stationary transparent drum

Also Published As

Publication number Publication date
BE395149A (en)
BE405608A (en)
NL43702C (en)
FR46290E (en) 1936-04-08
GB441761A (en) 1936-01-22
GB451578A (en) 1936-08-05
FR45574E (en) 1935-10-17
GB459602A (en) 1937-01-06
NL44585C (en)
BE412530A (en)
GB466571A (en) 1937-05-31
NL45395C (en)
FR779533A (en) 1934-04-08
FR46082E (en) 1936-02-15
GB445428A (en) 1936-04-09
FR773649A (en) 1934-11-22
FR46739E (en) 1936-08-10
US2226992A (en) 1940-12-31
GB453463A (en) 1936-09-07

Similar Documents

Publication Publication Date Title
US2163215A (en) Television transmitter
GB542436A (en) Improvements in arrangements for controlling the transfer of signals, particularly applicable to television
GB1400427A (en) Video signal processing apparatus
US2268001A (en) Television transmission system
GB648304A (en) Improvements in television systems, more particularly for colour television
US2564017A (en) Clamp circuit
US2295059A (en) Television receiver
US2353018A (en) Television apparatus
US2402096A (en) Control circuit
GB1297060A (en)
US2223982A (en) Radio system
US2296050A (en) Television circuit
US2353876A (en) Signal mixing amplifier
US2298863A (en) Image transmission system
US4502076A (en) Selective efficiency videofrequency non-linearity correction device
US3011018A (en) Highlight aperture correction system
US2254204A (en) Television system
US2326907A (en) Television system
US2932693A (en) Secret communication system
US2227002A (en) Television transmission method
GB386849A (en) Improvements in and relating to television systems
US2505367A (en) Television receiver brightness and contrast control
US2710347A (en) Interference reducing circuit
US2707268A (en) Pulse width modulation system
US2227492A (en) Television receiving apparatus