DE2028631A1 - - Google Patents

Description

RCA Corporation, New York, V, St.A. Television receiver.

The invention relates to a television receiver, in particular one for several operating modes with which Receive wireless RF television signals as well as video signals from a tape recorder, television camera, or other suitable video source permit.

Television receivers are widely used for entertainment, Educational, educational, instructional, industrial and other purposes. In many places besides the known ones Television broadcasting stations consist of other stations whose main role is to provide educational programs and information Kind of transfer.

A receiver used in this particular environment should, in order to be universally usable, desirably both these broadcast programs and. tape can receive pre-recorded data · Furthermore, some teaching systems are equipped with camera devices with which a classroom performance or other relevant event recorded locally and over a cable system can be transferred to several other locations. The signals that such a receiver can process are corresponding must, of fundamentally very different kinds.

The main differences are as follows:

009851/1890

In the case of HP transmission, the video information is modulated onto a carrier, which is received, amplified, and converted into an IF signal. must be gain controlled and then demodulated. Tape devices and cameras, on the other hand, directly deliver a standard standardized video signal (e.g. NTSC signal) that is not modulated onto a carrier. In the case of HF transmission, different Disturbances in the signal before the demodulation of the useful video signal influence. Such influences are frequency and phase dependent, so that in the construction of the receiver, Appropriate measures must be taken to ensure optimal reproduction. j

For color transmissions to such faults or ■ distortions spread even more, so that whether a color television receiver additionally certain precautions · must. These include an optimal training of the IF and RF amplifiers and certain equalization ^ - and _{Verzögerungsmaß-:} participated in the chrominance and luminance channels of the receiver.

When a television signal is not broadcast wirelessly and. is not modulated onto a carrier, but in the form of the actual borrowed NTSC signal or a video signal that corresponds to the signal ^; which is normally obtained in the receiver by the demodulation process is available, such a signal can be fed directly into the first video amplifier stage or into the video amplifier chain. However, if the receiver is also to be able to process a transmitted HGr signal, such a signal can only be entered successfully if the differences between the direct video information signal and the video signal obtained from the transmitted RF signal are taken into account. A receiver that can be coupled in the sense that it can receive both a transmitted RF signal and video signals originating from other sources, for example a tape recording, must process and resolve these differences.

009851 / 1Sii

Eb is to be expected that in the very near future the general public will have tape recorders, camera equipment and prerecorded Ribbons for normal home receivers with both color and black and white reception will be available. These devices and products will enable consumers, for example, to make their own colored tape recordings and play them on his television receiver or buy pre-recorded tapes for this purpose. Furthermore, the consumer if such means are at his disposal, in certain Cases have a desire to broadcast a television broadcast Tape the program he receives on his home receiver for future use. To one for such To realize the purposes of usable universal television receivers, one must, as will be shown later, certain considerations Take into account, so that you get a receiver that is relatively cheap and still an optimal reproduction guaranteed.

The invention is based on the object of such Multipurpose television receiver that meets these requirements, Create BU. According to the invention to solve this problem provided television receiver includes an automatic gain control circuit (AGC circuit) of known type as well as one selectively operable arrangement, which the receiver on a first operating mode switches, in which he receives a reproduces a television picture with a radio frequency carrier modulated by a composite television signal. The selectively operable arrangement can also be switched to a second operating mode, in which the receiver responds directly to an external video signal, that is not assigned to a high frequency carrier. In a third mode of operation, the receiver delivers a video signal in the form of a Composite television signalsB for external use. The automatic gain control circuit is arranged to: when the selectively operable arrangement on the second and / or third operating mode is switched, can act on the external video signal and on the internally supplied video signal.

009851/1890

ORiGSMAL BATHROOM

The drawings show:

Figure 1 shows the block diagram of a television receiver one controlled by the receiver's AVR circuit Amplifier according to one embodiment of the invention;

FIG. 2 shows the block diagram of a color television receiver, which can process both external video signals and video signals modulated onto an RF carrier;

FIG. 3 shows the circuit diagram partly reproduced in block form a color television receiver for receiving and recording transmitted RF signals βο as for the direct processing of external video signals; and

Figure 4 shows the circuit diagram of a horizontal oscillator and Phase detector arrangement in an inventive Universal receiver can be used

In setting up a television receiver to receive video information that is not modulated onto a carrier, it is desirable to input the video signal directly into the receiver's video amplifier. The input signal should preferably be approximately equal in size or its level to the signal level that prevails at the input point when the receiver processes a transmitted RF signal. In the case of a receiver with vacuum tubes, for example, it would be desirable to input the signal at the grid or at the cathode of the first amplifier stage, ie the video amplifier stage immediately following the video demodulator. The automatic gain control circuit (AGC circuit) of the receiver, which is usually controlled by this amplifier stage, then receives a signal that corresponds or is similar to the signal that is fed to it during normal receiving operation. In normal reception operation, ie when receiving a transmitted RF signal, the AVR circuit regulates the gain of the tuner [ and the IF amplifier so that regardless of fluctuations in the ·

Ü09851 / 1IS0

BATH

Antenna Signal Strength the current level of the horizontal sync pulse peaks held at a predetermined value will. Automatic gain control is a common function that a typical television receiver can perform, in all channels and in all signal propagation conditions to offer optimal reception. If the receiver is not processing an RF signal, the AVR circuit can still in conjunction with another video source such as tape, television camera, etc.

In Figure 1, transmitted RF television signals with the antenna 10 are received, the input of the receiving part 11 of the television receiver with tuner, IF amplifier and Video demodulator supplied. The RF signal is amplified in the tuner and converted into an IF signal with a lower frequency and demodulated, so that a demodulated signal is available at the output of the video demodulator. These functions are general known and in most color and black and white receivers realized.

The output signal of the video demodulator is fed in the usual way to a video amplifier chain 12 and from there to the picture tube 14. The deflection part 15 coupled to the video amplifier 12 on the input side is also attached to the picture tube 14 ^! coupled to the sync, deflection and high voltage generator circuits. The deflection part 15 supplies the deflection signals and operating voltages for generating a raster on the screen of the picture tube 14.

Most receivers have a keyed AVR circuit 16 provided, which increases the gain of the tuner and the IF amplifier regulates so that regardless of the receiving ' signal strength the current sync signal level at a is held at a predetermined value. The keyed AVR circuit supplies the control voltage that corresponds to the size of the video signal is proportional at a certain point in the video amplifier chain and the RF amplifier or tuner as well as the IF, Amplifier is supplied to help when increasing or decreasing

009851/1110

the received signal strength at the antenna the gain '■ this amplifier downloaded or · heraufzuregeln. In this manner, the Synchronisierinfarmation leading part of the signal amplitude in the Smpfänger is relatively constant and independent \ of the channel, is tuned to which the receiver or from the normally expected different reception signal strengths * held at the antenna 10th

The AVR function in Smpfänger is therefore relatively: important in terms of optimum reproduction over a ^wide: range of changing signal amplitudes. >

In FIG. 5, a switch 20 with three contacts is also coupled to a tape recorder (tape recorder) 21, a television camera 22 and a further video source 23. The movable contact or Ana of the switch 20 is connected to a potentiometer 24, the wiper of which is alternately coupled via a capacitor 25 to the input of a DC-coupled video amplifier 26, the output of which is connected to the contact arm of an operating mode selector switch 27 the one fixed contact or pole of switch 2? a connection to the input of the video amplifier 12 is established ₉ while this connection is interrupted when it is set to the second pole. 'The input of the DC coupled fideo amplifier 26! is also coupled via a resistor 29 to the output of a second DC amplifier 30, referred to as • 'polarity ^{amplifier 1} '. The input of the amplifier 30 is connected to the output of the keyed AVR circuit 16 via a further section 31 of the operating mode selector switch 27. By means of another contact 32 See operational. mode selector switch 27, the receiving part 11 can be switched off from the operating voltage B +, so that the tuner, the ZV amplifier; and the video demodulator can be switched off. In FIG. 1, all of the above-mentioned contacts of the operating mode are switched to the video monitor position. The switch 20 is switched

009851 /

switched to the output of the tape device 21, the signal thus at the potentiometer 24 appears · Hit the potentiometer 24 the input signal level is regulated or adjusted to allow the device to handle the various expected signal levels from tape devices, cameras, and other video sources. With the relationships shown in Figure 1, ie. When the mode holder is switched to video monitor mode, the receiver works as follows.

The tuner, the IF amplifier and the video demodulator (Receiving part 11) are switched off because of the switching off of B +, so that no signals to the video amplifier due to HF transmission can arrive. The tape device 21 (e.g.) is with its output to the input of the DC-coupled Video amplifier 26 turned on. The video amplifier 26 receives the signals played back by the tape recorder, amplified it to a suitable level and switches it via the switch 27 to a stage of the video amplifier 12 close to the input. The video amplifier 26 is preferably coupled to that stage or pre-stage of the video amplifier 12 which the Synchronizing and AVR circuits. Thus works on Input of the signal from the tape recorder of the receiver in the usual way Way. However, the signal from a tape, television camera, or other video source may be jammed due to the peculiarities of the respective source change in amplitude. A corresponding setting of the potentiometer is therefore just as important as ia for flawless playback Case of RF transmission

The gated AVR Sehaltung 16 is turned on via the switch section 31 to the ^te leiehstro "polaritäteveretärker 30, which is coupled with its" Auegang via the resistor 29 to the input of video amplifier · 26 · It serves signal voltage tone of the AGC circuit 16 after amplification by the polarity amplifier 30 for biasing the input of the gleiohetrome-coupled video amplifier 26 via the resistor 29. Due to the polarity of the supplied signal results

Q-09851 / mO

BADORiGlNAL

028631

a negative feedback for the amplifier 26 ₉ while the direct current amplifier 30 provides sufficient strength to keep the instantaneous level of the horizontal synchronizing pulse peaks at the same point in the video amplifier at the same predetermined value.

As shown in FIG. 1, the A VH-S ehalt wag 16 thus becomes part of the automatic tensioner © i @ es for the lonitor operation of the receiver in connection with other video sources. The advantages of this special system are that the operating points of the amplifier 12 are the same as in normal operation when receiving transmitted RF signals. As a result, there is only a slight shift in brightness when switching the operating mode between the various external sources and RF reception. Due to the fact that the synchronization signal peaks are kept at a fixed level by the AVR, there is also an effective black control (reintroduction of the direct current component). äes _{SigBals 9} coupled to the picture tube so that the viewer is offered an optimally bright picture «

The vaccinee's own AVR attitude 16, which normally acts on the tuner and IF amplifier, is therefore used to advantage when the receiver works as a monitor device for reproducing other video signals. This preserves all the advantages of the AVE, which are required when working with external sources such as tape recorders, cameras, etc., while at the same time it is ensured that what it is based on its construction is extracted from the remote receiver can accomplish without any noteworthy changes as the inner leimgräaeem of the · Eapfanger · be made. Bend aetsi; the recipient will be able to work ia essential eo % u «how © i? should work with HF transmissions by switching the operating mode selector shown in Figure 1, it is only when the g®3tri © li © lt S @ .rg © etell t «position is switched.

The above-described utilization of the AGC circuit can mil; the same advantage realized with black and white as well as parb receivers will.

Figure 2 shows the block diagram of a color television receiver, which affects both the reception of transmitted RF programs and the playback and control of Video signals received from other sources such as a television camera

22, tape deck 21, or other suitable video source 25 originate, can be adjusted.

The television receiver of Figure 2 operates with the same AVR scheme as the receiver of Figure 1, so that the same Circuit parts that fulfill corresponding functions are denoted by the same reference numerals. The Farhempfaxiger It differs from the black-and-white receiver mainly through the chrominance channel, one of the essential components of which is a chrominance intensifier 40 belongs to the one or more stages of selective bandpass amplifiers with a given gain and there is a frequency response centered within the color carrier signal range. A color burst separator 41 is periodically gated into the conductive state by a pulse taken from the horizontal synchronization circuit of the deflecting part 15, so that it has a amplified version of the color synchronous signal vibration train transmitted in color broadcasts supplies. The output of the color sync separator 41 is to a chrominance or reference oscillator 42 coupled, which has a phase-synchronized output signal with the color carrier frequency for the demodulation of the color carrier sideband aales supplies. The reference oscillator 22 is therefore on the output side coupled to one input of the color demodulator 43, which has another input to the output of the chrominance amplifier 40 is coupled. On the output side, the demodulator 43 is coupled to corresponding electrodes of the color picture tube 45, which can be a three-beam shadow mask tube.

009 851/1890

ι ~ ιο-

An APR and color blocking device 46 is on the input side coupled to the reference oscillator 42 and serves to the Amplitude is the color sync signal at the output of the chrominance amplifier 40 keep it relatively constant regardless of fluctuating input signal strengths at the antenna «, this so-called automatic color control (AFR) complements the action of the AVR for

the higher-frequency color-type components which, due to the properties of the propagation path and other changes, experience selective attenuation or attenuation. In addition, the APR and color blocking circuit 46 serves to switch _{off or on 9} d & si chrominance amplifiers 40 during black and white transmission _; Block in order to prevent interference or frms signals from affecting the output. The circuit components above are well known and are present in most conventional color receivers.

As usual in a color receiver, there is a delay line 47 in the luminance channel to compensate for the greater run or delay 5, which the chrominance signals experience when treated with a narrowband chrominance amplifier compared to the luminance signals amplified in the broadband luminance amplifier (video amplifier 12). In the delay line 47, the luminance signals are delayed in such a way that they arrive at the cathodes of the picture tube at the same time as the arrival of the associated chrominance signals at the grids of the picture tube. If the receiver is in the Work t Videoaonitorbetrieb, ₉ is switched off wis in connection with Figure 1, mentioned "for example, the operating voltage B + via the switch 32 from the IF amplifier. The switch 32 can be a suitable disk or contact arrangement on the mode selector switch 27 "The receiver" can now process a video signal input directly into the video amplifier.

If the IF amplifier effect fails, ie if the IF amplifier is switched off, however, a

.009Θ51. / 1890. BADORiGINAL -;

¹ -11-

Interesting phenomenon, when the delay of the delay line 47 is now too long and consequently the parbaric signals with this delay, under the conditions prevailing in a normal receiver before the arrival of the luminance signals at the cathodes on the screens of the picture tube, Ee must therefore be a Conventional receiver can process both signals that are wirelessly transmitted by means of a carrier ₉ and video signals that are received directly from an appropriate source such as ainea tape or a camera, the delay of the luminance delay line 47 can be shortened or decreased a contact 48 is connected to the operating mode selector switch which shorts a part or section of the delay line 47 when the receiver ^{: is} operating as a monitor device for the reproduction of color video signals from tape or from other sources. ;

FIG. 3 shows the circuit diagram partly in block form a typical commercial color television receiver modified so that it both wirelessly gassed RF signals as well as video signals from other sources.

The antenna 49 is coupled to the input ■■ of the HF suner 50, the output signal of which is fed to the IF amplifier 51 is. The ZP-Veratärker 51 is on the output side at the input of the video demodulator 52 and to the audio part 54 of the receiver coupled. The video demodulator 52 is coupled in the usual way directly to the input of the video amplifier, the in this Pall has an input stage 56 with a pentode. The anode of the pentode is attached to the grid of an amplifier triode 57 coupled, the an anode and a cathode load resistors stood for the control of the synchronizing and AVE circuits or the luminance channel has,

The anode of the amplifier triode 57 is connected to the input of the Synohronisiersignal-Trennstufe 61 and a resistor 62 to the input electrode of a keyed AVH pentode 60

009851 / ItSO _BAD orsgsmäl

COPY

coupled, -The pentode 60 is scanned with positive pulses ₉ which are fed via a capacitor 63 coupled to the anode of the pentode 60 and the deflection circuit 64. The gated pentode 60 supplies to its anoi © a control voltage ₉ which is proportional to the amplitude of the syachronization area of the signal given to the grid. The. Anode load contains suitable BC filter elements % w & filters the control voltage gate whose feed line to the Hl ¹ and ZP amplifiers. The deflection circuit 64 contains the vertical and horizontal deflection stages with return transfor- mator and the various high-voltage stages ₉ as they are normally present in a conventional receiver

The deflection circuit 64 provides two outputs X and Y, the deflection yoke 66 of the picture tube 67, which can be a three-beam shadow mask tube ₉ with the required horizontal and vertical angles

The control signals for the deflection circuit are ^{supplied by the Horizontalossillstor 68 and the Vertical OsgillatoE 1} 69, which are synchronized by the Synch3? Onisiereignal-Tr @ nn @ tufe 61. As usual in such a receiver, the chrominance treatment circuit 70 with the Parbart bandpass amplifier ₉ the color sync signal separator @, the reference oscillator _{9 of} the AFR ~ Saiialtuag and the color lock from the input stage 56 of the video amplifier © controlled ₉ with its anode a condensate? 71 is alternately coupled to the chrominance treatment circuit 70. The outputs of the earbart treatment circuit .70 are coupled to the color demodulator 72 * the color difference signal © -füE supplies the feed line to the picture tube 67 via the color driver stages 73. The cathode output of the video amplifier circuit 57 is normal reception mode via a switch contact 74p © la © gerungeleituag 120
75 on the entrance
line 76 coupled «Di®! © rgSgennagileitiim ^ 76 is

side coupled to the input of a video amplifier 77, the cathodes of the via a suitable control network 78 Picture tube 67 with the relatively wide-margined luminance signals controls. The delay lines 120 and 76 are used to ensure that the broadband amplified luminous esinals at the cathodes of the picture tube 67 approximately simultaneously with the arrival of the chrominance signals at the picture tube grids arrive. The recipient, as far as described so far, is with the exception of the switch contacts 74 and 75 and the split or split delay line 120, 76 of conventional Art.

It will now be described in detail the additional circuit that is in the receiver for the reception of external Video signals originating from a tape recorder or a camera, for example, is provided.

The switch contacts 74 and 75 mentioned are contacts on the same switch, the other contacts 80, 81, 82, S3 and 84 controls «, each of these switch contacts is a single-pole changeover switch although other suitable switch arrangements can be used. Referring to Figure 3, there is a switch operating diagram shown, which indicates that when the switch contacts 74, 75 and 80-84 into the dashed line Position, or upwards, the receiver usually processes an HP transmission. When the switch contacts are on the ones shown in the drawing Positions are switched, the receiver responds to an external video signal from the above sources originates.

In the switch position illustrated in Figure 3, corresponding to the use of the receiver as a video monitor device, is a source of external video signal on terminal 86 coupled, in turn, to one end of a potentiometer 87 is connected. The potentiometer 87 serves as an input signal level controller, which enables the user to adjust the strength of the signal sent to the receiver.

The Grinder, eles Pot ^ atioEasters
88 to the base of a

moderately coupled »The © .1 © Ifetttss'iolg®? designed booster transistor 89 is with soisäQB K © ll®lst © E · üTbar @ in @ n gremsungswiüerstand 90 aa eis © BstriabsspssaimgsfMel] connected «The collector is through for üsshsslstroiasigiiale A capacitor 91 üfeeribMieHsto A Basisi ^ orspannetswerlr for the Traneistor 89 mitcäs UiaQgutaadoa 92 and 93 is between ■ fV and

of the graasistor® 89 is located

Beaiagepotential (Mssse) asiö is ülbss ¹ ®ia © Spul © 95 an di © ein @ e Yerstaiikertrsfflsiistogs 9β ®ag @ lkopp @ lt _ö cltr in Emitter— aBssel © (gt is mslü © i® © K @ ll © kto2? Liaiitη consisting of

the + V and iea collector of this feaasistor-coupled series circuit rack of a resistor 99 ^ aaa of an Eatzernmgsspule 10O ₈ cries ".

The swischea d © ai Eait * fe @ s ^> üqb SE'saeistor® 89 bath of the base & ez transistor 9 <S li © g @ mi @ ipml® 95 is in Sssianresoaaa ^ with a KondenBatog 101 _g äss in the ® © i & @ © it a® Q-attenuation resistance 102 a? iis © hen öi © Bssi® üq & Srsffl.Bis © r® 96 and ground is connected © Bi © Spul © 95g äer loai®ia®ator 101 and the resistor 102 form eiaea lesoaaiigteeis with low Q ° value ₉ • which works as a ZP-Teratärkersiaulator for the Parbträgereignalkoiaponenten »Ber Ioll @ ktor äee transistor 36 is to the base of a Terstärlerteansistora 105 aag @ k @ pp © lt _g the sit its emitter over the series connection of the resistor © 106 and 10? with + V__ Terbunden is «, %> wLB®hen the yerbiming point of the

Cw

Resistors 106 "and * 107 on the one hand and ground üade ^? Ers @ its is a bridging or Ibleitfeondeasator 108 coupled» The collector of the Transistor® 105 is located in a resistor 109 at Ilasse and at the switch of the switch Θ3 ₉ ä @ r ₉ is switched to receive external video signals as shown. The switch 83 couples the collector ö @ s fransistörs 83 with that of the first video amplifier station 56 _o Di © @ e the direct coupling &<so

2028531

amplified video signal to the cathode of the first video amplifier stage 56. When setting to video monitor mode (reception of external video signals), the switch contact 80 the operating voltage B + from the IF amplifier 51 is switched off. As a result, the receiving part of the receiver is switched off, so that no HF signals are used in video monitor mode

can be received and processed. The Veretärkerpentode [

56 amplifies the signal coupled to its cathode, so that!

it delivers amplified video signals to its anode, such as ',

would normally appear there at HF <? £ reception. Furthermore _:

is through the coil 95 in connection with the capacitor 101,

t the video signal from the external source intentionally influenced as it would be if it were demodulated ' of an IF signal would have been obtained.

To this end, the low Q series network is sized so that its resonance peak is at approximately 5.08 HHz or a little below. This allows the ink carrier sideband frequencies to be on the falling for sale the bandpass curve are amplified. When transferring RF signals would have the chrominance or color carrier sideband frequency ζen through the ZF amplifier on the same point relative same slope of the bandpass curve of the IF amplifier amplified.

The purpose of this series resonant circuit is low Q bit it is therefore an optimal video signal (e.g. NTSC-Sig «· nal), at which the amplitudes of the chrominance and the Luminance components are relatively flat and none Distortion in the course of propagation or by the IF and RF amplification experienced intentionally distorting it.

Many stages in a receiver are designed to adequately process the transmitted RF signals. Examples include the band-pass characteristics of the RF and IF stages, "etc. Considering these facts, the optimum video signal aufi the receiver are vorverserrt so before coupling into the first video amplifier stage that it rom receiver

0-09861 / ittO-

can be processed in the usual way. The amplified © signal at the anode of the pentode 56 is now coupled in the usual way via the capacitor 71 to the Parbartbehandlungssßhaltung 70 and from there to the rest of the Parbart circuit, so that the picture tube 67 is fed with the correct color control signals As far as the larbart treatment channel is concerned, there is no difference between these external signals and signals that it would receive with HF reception. The normally present in such a receiver Parbartentzerrnetzwerke equalize after wi © before the chrominance signal before entering into the demodulator * vm the "Abroll.en" the chrominance components due to the ZP-Prequenzgangee% u compensate etc. The Parbartentzerrn © tsw © strength need not be changed or to be influenced, since the video signal has been intentionally pre-distorted by the influence of the coil 95 and the capacitor 101, as mentioned above.

The amplified video signal to the anode of pentode b6 wire on the grid of the Verstärkertriod® 57 coupled ₀ Dae at the anode of the triode 57 appearing amplified © signal is of course, still via the resistor 62 to the keyed AGC pentode 60 coupled and the synchronizing signal -Separation stage 61 fed. In this way, the horizontal and vertical oscillators 6Θ or «69 semi © receive the deflection levels 64 similar or similar signals, as they would be received in normal reception (HP transmission)? so that they supply the necessary voltages and deflection currents for dig 'rast successful beam deflection. On the other hand, the AVH-Sehaltung _8, which is normally connected to the tuner and the EP amplifier, works, but does not regulate this §5tmf®n * because it disconnects the operating voltage B + ψ © η s _o B « & ®m ZP -Veretärker 5% auegeecn & ltet ß ± m \.

However, the anode of the pentode is 60 timr Wlieretänäe 108 ₉ 109 and 110 ait the cathode of a diode 111 g © k @ pp <§lt _$ SI® with its anode is coupled to the base of an amplifier trameistor 112, which is connected to its base Mass® Xi @ gt - ^; Miä with his collector at the connecting road £ uiikt o.er

93 connected in the base biasing network of transistor 89 is. The cathode of diode 111 and the base of the transistor 112 are also connected to the switch contact via a resistor 114- 84 connected, which sends a voltage + V "through the resistor 116 in the video monitor mode, through which the transistor 112 and the diode 111 are forward-biased. To this Way is with forward-biased diode 111 by the am Resistor 110 in the anode circuit of the pentode 60 appearing AVR voltage fluctuations the bias of transistor 112 is modulated or changed. The transistor 112 changes the current of the transistor Ö9 by controlling after its current conduction its base current. Consequently, due to the changes in the collector current of the transistor 89, the operating voltage is applied the base of transistor 96 changed. The transistor 112 It also reverses the voltage fluctuations linked to its base reverses their polarity to ensure that the automatic biasing action is in the correct phase corresponding to the number of preamplification of the outer The stages used in the signal.

The way it works is as follows. If the DC level of the signal at the base of transistor 89 becomes too positive, the DC level of the signal coupled to the cathode of first video amplifier stage 56 also becomes too positive, so that consequently the DC level of the amplified signal at the anode of pentode 56 also becomes too positive . The AGC key pentode 60 therefore receives a video signal at its grid with such a DC level that it cannot conduct, ie is locked * In this mode of operation, transistor 112 therefore conducts more strongly. The increased current conduction of transistor 112 suppresses the DC voltage at the base of transistor 89. In this way, the transistor 96 eugeführten signal \ j lowers the DC level as the DC level of the appearing at the collector of Transistonp 105 signal which is the cathode of pentode 56 ssuge J-leads. This will reduce the DC level at the anode of the!

009851/1890

Pentode 56 lowered. In this way, consequently, the level of the video signal at the anode of the pentode 56 becomes approximately kept the same value as with normal HP-Smpfang so that the AGC circuit can conduct and the preload and operating points of the video amplifier can be kept relatively constant and under the influence of the AVR.

The amplifier triode 57 controls its cathode and switches 74 and 75? The other contacts of the switches 74 and 75 are coupled by the delay line section 120 when the switch is switched to RF interception mode (switch arm upward). The delay line 120 is therefore in series with the delay line 76, as mentioned above, so that there is a longer delay for. gives the luminance channel with HP reception than with reception of the external video signal. Would with HF reception _with the same delay! worked as when receiving external video signals, so when receiving the external video signals the light-emitting signals would arrive at the cathodes of the picture tube after the arrival of the chrominance signals at the grids The IF amplifier and the HF amplifier are switched off and consequently cannot delay the chrominance components of the signal mixture by a different amount than the luminance components. During normal HP reception, the chrominance components appear at the anode of the pentode 56 with an additional delay compared to the luminance components due to the properties of the receiving part before input to the chrominance processing circuit 70. This additional delay does not necessarily occur when receiving video signals from other sources.

The switch 81 fulfills when receiving signals from one Tape recorder or other external sources perform another useful task by providing the accompanying sound portion of the external signal, the

009851/1 890

- ■ BAD ORiGSMAL COPY

20236 ^ 1

recorded on a separate tape track or from a suitable audio amplifier circuit can come from an auagangaseiten coupled to the preamplifier 121 connected to the switch on the audio part 54 of the television receiver. These Coupling can take place via the volume and tone controls of the receiver * Bas ao coupled audio signal bypasses the Sound demodulators, as the sum also belongs to the video signal anassr's sound signal appears in its original form In this way the video signal can be wigdergagabsn on the screen of the picture tube, while at the same time the accompanying sound is played through the receiver's loudspeaker, ao that the viewer @ in® is offered normal performance «

The switch 32 lies with its switching arm to ground and is old powered his two contacts or poles at the Horizontaloazillator 68th A resistor 123 is located next to that contact of switch 82 to which HP reception is switched. The other contact which is switched to when external video signals are received is connected directly to oscillator 68. ■

The switch 82 fulfills the following tasks. During normal reception operation, the horizontal analyzer 58 is synchronized by the synchronizing signal separator stage. A phase detector provides one of the phase; difference between the Synchronlsieriapulsen and the Oeziilatorschwetzung corresponding Hegel voltage for the frequency control of the horizontal oscillator 68, so that it is synchronized in the correct phase. The output signal of the phase detector is pre-filtered in order to prevent interference and other components from incorrectly influencing the control voltage and causing the oscillator 68 to “step” in terms of frequency. Ib normal CCFP narrow-band filtering is operational undergo mis sail tension before supply to the oscillator, because with RF CCFP "ng worse or ungünetlsere aauoch- or SNR ·" α expect are ·

009SS1 / 1U0.

GOPY

»20-

Upon receipt of signals from other external -Sources ^ particularly from a tape device, however, brings a © Such filtering the cable tension before supply to the oscillator problems "at a typical tape recorder for recording and playback of YideoSignalen including those Signalgemiaehe _f as are required for a larb transmission, helical line scanning is used ₉ whereby the recording and playback of the video information takes place with the help of several, usually two magnetic heads *

Typically, this will be two at a distance of 180 on a head wheel arranged magnetic head used e - _t one of which in each case always takes place from the belt ₈ when the other runs on the ribbon ,. Because of mechanical tolerances, the tape recorder and the alignment of the heads, the width of the horizontal synchronization pulse can fluctuate, as it happens that during playback the head running onto the tape begins to play the horizontal synchronization pulse in a different phase than the one just running off the tape Head * Bas intended for the phase detector with HF reception® filter-. network is measured in terms of the expected noise level of the incoming video signal, "Bas Filternetawerk verlang- = · including therefore undesirably Alisprechgeschwindigkeit the Phaeendetektorausgangssignal ® © hr _g than is necessary in order to Phasenstörimgen in a playing signal to carry Reehnung . Consequently, the filtering behind the phase detector must ^; «Here the switch 82 is provided» which has the effect that the amount of effective filtering is reduced in video monitor _{mode 9} so that the phase detector for the "horizontal oscillator 68" reacts to any phase changes of the horizontal synchronizing impMlseB b @ i the bandirf.efierga "b @" · Can. Due to the enlargement of the filter pass range, the receiver can follow such fluctuations more quickly during monitor operation and consequently maintain the phase synchronization of the horizontal oscillator 68 even in the event of disturbances accompanying the horizontal synchronization pulses. -

• 0098S1 / 1SSÖ .. -. "■

From the above description it can be seen how the recipient should be modified in order for the different signal sources, each with optimal reproduction regardless of the way in which the video information is obtained to be ready to receive.

Another function that such a universal receiver has to fulfill is the possibility of tape recording TV broadcasts received in HG operation. As already mentioned, for the purpose of receiving RF transmissions, switches 74,! 75 and 80, 84 in the position shown in dashed lines (contact arms up) switched.

As shown in Figure 3, the cathode of triode 57 is on

coupled to the input electrode or base of an amplifier transistor j 125. Between the cathode of the triode 57 and mass \ is a selective network. A resistor 126 is connected between the cathode of the triode 57 and the base of the transistor 125. Between the base of the transistor 125 and ground there is a series connection of a resistor 127 and a coil 128 as a voltage divider for the bias of the transistor 125 Resistor 127 as well as to one. j. Capacitor 132 is an RG series element 130, 124 for RF compensation. Parallel to coil 128 is a capacitor 131 which, together with this coil, is in resonance at the higher-frequency end of the composite signal spectrum or in the vicinity of the frequency range of the color carrier components.

This resonance network mainly forms an equalization network work to equalize or increase the color carrier components of the signal mixture at the cathode of the triode 57 »so that the attenuation or attenuation of these components in the IF and RF amplifiers is compensated. In this way the Amplitude distribution of the applied to the base of the transistor 125 Signal essentially the usual standardized video signal (e.g. NTSC signal). The emitter circuit designed transistor 125 has a collector load resistor 135 and a Cathode negative feedback resistor 136. Between the collector

009851/189 0

The transistor 129 rad ii®! © si © a © © fe®asietor® 139 is a delay contribution 138 g © kopp @ lt ₀ walohs © in® diff @ r @ ntielle delay s ^ lmokem this

How early is it generally necessary to delay the exercise of a delay than with HF vaccination, generally this is Ϊ ¹ © !! al © HI ⁵ · = - and "ZP ^ Veratärlbar addressed werdea _s so @ lb @ @ Nfall eisa © äiff®r @ atiell @ fer

about 0 ^, 2 mics © sekunä®a gQgdaülbsr d © r? © rgög © ration between these Komposisatea b® ± f®g & rh @ ± t-aMg through the HF »and ZF stages, we went around a banoe, tt £ aal »@ device with a aufaeiekmiMigsgar®elit © n Sigael sia sp®isä @ n ₉ - one must the differential a Tersdgesraag of O ₉ 2 likrostkuad © swischisn Parbart- and leuelitdiclitekosaponenteap on the video demodulator due to the influence of the Hf- uni Z. = »Steps appear, carry recimation © Hiersm disat öi © ^" © rsö ^ erungslei'Sung 13Θ, so that the on fi @ ® Baafi aMfg® ^ @ i © Ma © t® signal again at the ütolisheB g @ norait © 3a Ifiddösignsl (^ ₀ B ₀ ISSG-SigBal) corresponds to t in wolelieia keia © a @ aa © n @ we2? T @ iiff © r © ntielle ¥ er »delay between Lomefetdiiolat © · = unä ^ arlbartkoaipoiienteii exists«

The Yeretärkertraasistor 139 Tsr strengthens the sainer base supplied signal mix aad conducts the Yerstärkt © signal the basis of a close-coupled ¥ © rstäÄertransi0torstufe 140 to, which is also designed in Äitterschßltung and the composite signal on a a for the © feed line to the input a buffer core transistor © r®taf © 145 suitable level further strengthened The buffer transistor 145 lies with his Collector through a working resistor 146 in the earth and is with its emitter via a counter-coupling resistor 147 to the operational tension qu © !! ® +? angeefelossano Ba® A composite video signal is generated via a large capacitor 148 an output jack 150 for video recording AC coupled. The output jack 150 came over other suitable arrangements with de® input for the recording of the fileosignales ¥ erbund © a were «

oosasi / iise

With the receiver equipped with the additional circuit described above, transmitted HP signals that have been demodulated in the normal manner in the receiver to form a video signal can be used are recorded using a tape recorder. The audio part of the receiver is in the meantime via switch 181 The position shown in dashed lines is switched on so that the audio signal, after demodulation by the audio demodulator of the receiver, is fed to an amplifier transmission stage 155, j The transistor 155, which is connected as an emitter follower, is with its! Emitter via a capacitor 156 to an output socket 157 coupled for sound recording, so that the accompanying sound together with the video signal by means of a corresponding recording; Household devices, such as one with helical scanning, can be recorded.

Figure 4 shows a horizontal oscillator circuit. the Circuit contains a triode 150, which is connected with its grid to a horizontal phase detector circuit with two diodes 151 and 152 is coupled. The horizontal synchronizing pulse from the The synchronization signal separator © 61 (FIG. 3) is the connection point of the cathodes of the diodes 151 via a capacitor 153 and 152 supplied. The horizontal oscillator signal is fed to the anode of the diode 151 via a capacitor 180. Means a capacitor 181, the signal amplitude is divided so that it is given the correct level. The diodes generate a DC control voltage on the output side, which is the phase difference between the horizontal synchronization pulses and the oscillator signal is proportional

The control voltage is dea grid of the triode 150 over a Resistor 157 leads. Filtering on the grid of the triode 150 takes place by means of a capacitor 158 coupled between the grid and ground in conjunction with the capacitor 158 coupled in parallel with it switched selective RC series element, consisting of one Capacitor 160 and a resistor 161 · The between anode and the cathode of the triode150 appearing amplified control voltage is via the series connection of a potentiometer 163 and one

Wideretandes 164 fed to the horizontal osillator stage.

009851 / 18ÖO

Between the cathode of the triode 150 and the grid of another Triode 165, two resistors 163 and 164 are connected. The triode 165 belongs to the horizontal oscillator stage, which with Feedback between the anode and grid of the triode via a tapped coil 168 and a capacitor 170 works. The control voltage coupled to the grid via potentiometer 163 causes the horizontal oscillator to synchronize with the horizontal pulses phase synchronized.

A matched parallel resonance circuit with a coil is located between the cathode of the oscillator triode 165 and ground 177 and a capacitor 178. This resonance circuit supplies i with normal reception operation a sinusoidal voltage with horizontal, Oscillator frequency, which in turn defines the control range of the oscillator; limited and the horizontal frequency within close tolerances ι holds by producing a relatively narrow bandpass filter for the oscillator in HP reception. >

If the receiver, as described in connection with Figure 3, is switched to receive external video signals, the switch 82 is in the position shown in FIG. 4, where the resistor which is parallel to the resistor 161 123 is switched off, so that the filter effect is reduced and thereby faster transitions or changes the control DC voltage can reach the grid of the triode 150. At the same time is in this position Switch 82 the tuned circuit with coil 177 and capacitor 178 shorted by the cathode of the oscillator triode 165 is connected to ground. This in turn extends the effective bandpass range of the oscillator, so that the oscillator over a wider range of control voltages can be regulated with sharper or faster transitions from level to level. In video monitor mode, the Oscillator changes its phase and frequency much faster according to the control information received from the phase detector change, so that he relatively rapid disturbances of the phase of the Horizontalaynchronieierimpulse, as they are when playing from Band may occur, may follow.

BATHROOM ORIGINAL

When the switch 82 is switched to RF reception, is the resistor 123 parallel sum resistor 161, so that the Total resistance of the parallel connection is correspondingly lower and the control signal for higher frequencies at the grid of the Triode 150 is more attenuated. In this case, the parallel resonance circuit coupled to the cathode of the triode 165 is also switched on, so that the control range of the horizontal oscillator is narrowed accordingly.

Below are sample values for various Circuit elements indicated in the arrangement according to FIG. Circuit elements that are not in this list have the values given in the drawing.

resistance 87 3500 ohms 90 10 ^M. 92 5600 " 93 5600 " 94 3300 " 99 1500 ^m 102 330 " 106 82 '". 107 18 " 109 220 ^H. 126 750 - 127 270 " 130 180 " 135 820 ■■ 136 330 " 146 82> 147 39 ^w capacitor 88 25 / UF 91 0.01yUF 101 39 PF 108 2200 ■ 124 560 131 470 "

009851/1990

capacitor

Stupid

128

330 P? capacitor 101 3UU
ia I. / WET
iQQQUB at approx. 2 12 © / uH ' capacitor 131 i © s © na Is at ca ₉ 4 άζ with ®5-3i, 1 aa with -4.5 »

213694

155 213694

111 iili®ifflili © de ₉ sB «, E0222

Claims (5)

-27 claims. 1. Television receiver with an automatic gain control circuit aο as with a selectively operable arrangement to switch the receiver to a first operating mode, in which modulated on receipt of a composite television signal HP carrier reproduces a television picture, characterized in that by means of the selectively operable arrangement of the receiver also a second operating mode in which it responds directly to a video signal without an HP carrier coming from an external source (21, 22, 23) responds, and / or to a third mode in which the receiver receives a video signal in the form of a composite television signal for external use, is switchable, the automatic gain control circuit (16) in the second and / or the third operating mode on the outer Acts on a video signal or on an internally provided video signal. 2. Television receiver according to claim 1 with a signal processing circuit, which generates a demodulated video signal from a video-modulated HP carrier signal, as well as with a video amplifier which amplifies the demodulated video signal and feeds it to the image display device of the receiver, wherein the automatic gain control circuit adjusts the gain of the signal treatment circuit according to the amplitude of the demodulated video signal regulates, thereby characterized in that the selectively operable Arrangement of the following facilities for operation in the second Operating mode contains: an amplifier (26) with adjustable bias voltage, the input of which can be supplied with the external video signal and which can be fed to provides its output with an amplified version of the external video signal; a first actuator (27) which is operated in State the output of the voltage controllable amplifier couples to the input of the video amplifier (12); 009851/1890 a & ölungssßhaltung & m b i © actuation of the first Betätigungeorgane the Signalb @ © haltnng off liandliangs® to the Signalbeha (11) docked second actuating member (32) _9; and one between the automatic® gain control! circuit. (16) and the Vorepannungsregelbaren amplifier (26) coupled device (3O) ₉ (27), the automatic Yerstärkungsregelschaltung in the position set of the video signal in the video amplifier (12) j the bias of the vorspannungsregelbaren amplifier in accordance with the DC level upon actuation of the first actuation organs to rules" 3 · television receiver according to claim 1 with a synchronous ^! siersignal-Trennetufüj, which derives a synchronization pulse from the received Signalgemisoh and is assigned to a phase detector that is assigned to a horizontal oscillator of the receiver, in such a way that by comparing the phase and frequency of the synchronizing pulse with the Ossillator signal © ine Hegel voltage is generated via a pilot network Oscillator is fed in such a way. that by regulating the phase of the oscillator signal this is phase-synchronized with the synchronizing pulse, characterized by an arrangement (82,123) coupled to the filter network (158, 160, 161) which, upon actuation of a first actuator (27) of the selectively actuatable arrangement The amount of filtering of the Hegele voltage is reduced if the external video signal is fed to the video amplifier (12) of the receiver » 4. Television receiver according to one of the preceding claims with a signal _{treatment BChaltung s} the reception of an HP carrier, which modulates the television signal mixture by a broadband luminance components and higher-frequency narrow-band color components containing ± st ₉ at the output © ines video demodulator, the television signal mixture, since a A urch in that the selectively operable © arrangement, the following devices aage- for the operation in the third mode a enthälts to the video demodulator (11) coupled · first circuit (125) _f oils upon receipt of the signal mixtures selectively in such a way on the chrominance components single 009851/1890 acts that their properties in relation to the luminance components are changed so that at the output of this first circuit a through the signal treatment circuit im. substantial unaffected composite signal is obtained; and a arrangement coupled to the first circuit (139, 140, 145) » which the signal to a consumer output for the outer; Use. j 5. Television receiver according to claim 4, in which the video-f demodulator the video signal mixture to a chrominance amplifier and ⁱ a luminance amplifier, both of which are coupled to the image display device of the receiver, since you roh geke η η ζ eich η et that the first circuit an equalization network (128, 131) coupled to the output of the video demodulator for selectively increasing the amplitude of the chrominance components relative to the amplitude of the luminance components; in that a delay line (138) is coupled to the first circuit and produces a predetermined differential delay between the luminance components and the chrominance components at its output, I such that a signal mixture with a relatively constant delay distribution with the frequency is obtained; and that an arrangement (139, 140, 145) for amplifying the signal to a level suitable for the feed line to the consumer output is coupled to the delay line. 6, television receiver according to one of claims 1-3 with a signal processing circuit which, upon receipt of a composite television signal containing luminance and chrominance components modulated RF carrier delivers a demodulated composite video signal with a delay line containing video amplifier, which amplifies the signal mixture and delays the luminance components and the image reproduction in front of the direction of the receiver, with a chrominance amplifier that shares at least one input with the Video amplifier has and amplified the chrominance components the image display device, and with an automat! - 0 0 9 8 51/18 9 0 -50- see amplification control circuit which, under control by synchronizing pulses contained in the composite signal, generates a control signal corresponding to their amplitude, regulating the amplification of the signal treatment s circuit according to the size of this; Control signal generated, thereby marked; net that the selectively operable arrangement is as follows. Contains means for operation in the second operating mode; a bias adjustable amplifier (89) o its; Input (86) the external television signal mixture can be suieitbar and at its output a strengthened version of this signal _; misch8 supplies; a circuit coupled to the output of this amplifier (9 <S »105) ₉ ^ i © by selectively reducing the amplitude of the chrominance components compared to the luminance components delivers a second signal mixture on the output side, in which the chrominance components have a different amplitude in relation to the Have luminance component tone than in the first composite signal; a first actuator (83) _s which upon actuation of the output of said circuit (9 ^ ₈ 105) to the common input of the Leuentdichte = and farbartverstärkers: coupled; Second device (60) coupled to the signal handling circuit, which switches on the signal handling circuit when the first operating device is actuated; _{a third device (7 $ 9} 7δ) coupled to the delay line of the video _{amplifier δ} äi © bsi actuation of the first actuation device, the delay of the delay line (76, 120) and consequently the delay between the light emitters te and chrominance components are reduced | and © in © zwäfichen the comatic '¥ e3fstrengthening r © g @ l @ © h®ltixng (60) and the bias-adjustable amplifier (89) coupled © fourth device (112), which is activated when the first actuation device the automatic gain control switch to position B @ t ^ t _{9 to change} the bias voltage of the pre-tensioning controllable lf @ F strength © rs according to the size of the ¹ synchronization pulse in the external television signal mixture ₀ . 009851/1890