DE2542502A1 - TELEVISION RECEIVER WITH A DEVICE FOR THE SIMULTANEOUS PLAYBACK OF MULTIPLE PROGRAMS - Google Patents

Description

German ITT Industries GmbH P.M. Flamm et al 4-4

78 Freiburg, Hans-Bunte-Str. 19 Mo / Be 2542502

23rd September 1975

DEUTSCHE ITT INDUSTRIES GESELLSCHAFT LIMITED LIABILITY

FREIBURGI. BR.

Television receiver having a facility for simultaneous playback multiple programs

Addendum to patent 24 13 839

There are television receivers already commercially available, where additionally in addition to the main screen, a second screen is much smaller in its area Screen is available, so that the viewer has another program of interest in addition to the program of interest running on the main screen Program can be followed on the smaller secondary screen.

In addition to the expense of the second picture tube, such a receiver is required generally two complete receiving parts for the different ones Programs, i.e. tuners, IF amplifiers, video stages and deflection circuits must be duplicated. This means one considerable additional effort.

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A different procedure was occasionally used at exhibitions demonstrated for the simultaneous visualization of two different television programs, see the magazine "radio mentor electronic", March 1974, p. 95. One of the images to be displayed was from a television receiver received and displayed in the usual way. · With a second receiver, another transmitter is received, its - The screen image is in turn scanned by a television camera. The output signals the television camera are then fed to the first receiver and alternately by means of an electronic switch shown, wherein the arrangement can be chosen so that the second image can be seen in an image section of the first. A similar process is also described in DT-OS 2 239 593. These solutions also involve considerable effort and are particularly useful for home recipients not feasible.

The main patent 24 13 839, on the other hand, is a television receiver for simultaneous reception of at least two programs, the structure of which is much simpler than the known one described at the beginning TV receiver with two separate picture tubes and receiving units. For a better understanding of the present invention, therefore, first the television receiver of the Haiiptpatents in detail with reference to FIGS. 1 and the drawing explained in more detail.

Fig. 1 shows schematically the front view of a television. recipient according to the main patent and

Fig. 2 shows the block diagram of the television receiver according to the main patent.

In Fig. 1 this is on the screen 2 of the television receiver 1 for the Viewer desired result shown, namely that on the majority of the screen 2, the program I, so for example a soccer game,

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is visible, while the further program II is made visible. With the usual 625-line standard, the number of lines can be of the image section 2a, for example, be 45 and the length of the image diagonal is about 10 cm. The number of lines and the number of pixels of the Image section 2a is therefore greatly reduced compared to the reproduction of the further program II as the main program on the screen 2. this is easily admissible, since in the image section 2 a generally a scaled down Overall picture of the further "program" is shown.

The block diagram shown in Fig. 2 of an embodiment of the television receiver according to the main patent shows the common signal path for both programs from the antenna via the tuner 3, the intermediate frequency (IF) amplifier 4 and the video amplifier 5 to the picture tube 6, this signal path in the usual way also the horizontal deflection stage and the vertical deflection stage 8 are assigned. The television receiver 1 also contains the audio amplifier 9 and the loudspeaker 10.

The memory and Switching stage 11, on the one hand from the output of the intermediate frequency amplifier 4 and the horizontal deflection stage 7 is controlled and in turn on the tuner 3, the intermediate frequency amplifier 4 and the video amplifier acts in a manner still to be described.

It is assumed that the tuning means of the tuner 3, for example Capacitance diodes with corresponding potentiometers for their voltage setting, are set to the transmitter for program I and the transmitter for further program II. The storage and switching stage 11 now controls the tuner 3 depending on the horizontal level 7 in such a way that that it is switched from program I to further program II during certain lines. During these lines the video amplifier by the switching part of the memory and switching stage 11 with their

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Memory part connected, whereby the lines of the now received and processed further program II are written into the memory. Apart from switching tuner 3 to the other program II a corresponding switchover of the throughput gain of the intermediate frequency amplifier 4 is also initiated.

The memory passes the information written into it to the video stage then off again when the electron beam overwriting the screen arrives in the area of the image section 2a.

The memory has the task of reducing the image of the further program II and the time difference between the. Switch to the transmitter of the further program II and the reproduction of this information. The reduction of the image of the further program II is achieved in that the output speed for the memory is greater than is the input speed.

It is advantageous to switch tuner 3 to the further program II to be carried out only line by line in order to disturb the reception of the program I as little as possible.

Since the flow of information during the switchover to the further program II of the program I to the picture tube 6 is interrupted, it is necessary to offer a "replacement program" to the picture tube 6 during this time. That In the simplest case, the signal determined for this can be derived from the mean brightness value, i.e. the average gray value of the preceding lines! In the color television set it is advisable to continue to display at least the color information, in the case of a color television set according to the PAL system, the color information to be displayed further corresponds to the color signal of the preceding one Line corresponds, d. H. the color information to be displayed is simply taken from the delay line in the device.

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Program I is least disturbed when on the color television set of the picture tube while the further program II is being written into the memory, in addition to the color information mentioned, also the brightness information is fed to the previous line.

In the latter case, an additional memory is required in which the brightness information of the previous line until you switch is saved to the further program II. This additional memory can be relatively simple if the bandwidth of the signal is toggled is reduced significantly, for example by a factor of 10. This can done without further ado, since the pixel resolution of this line does not need to be very high, because the line shown again does so is actually a "wrong" line. -

As already mentioned, the representation of the further program II as a reduced overall image that is written with normal raster resolution, that the number of lines to be stored for this information as well as the Number of pixels per line can be reduced by the image scale can. A good recognition of the program content is already obtained with approx. 50 lines with approx. 50 pixels. · ■

The memory contained in the memory and switching stage 11 for the other Program II is advantageously structured as described below. It consists of storage locations arranged in lines for the lines of the further program II, the number of memory lines being the number of corresponds to the lines to be saved. First of all, the first line of the further program II is written into the first memory line. During the tuner is switched back to program I, the first line of the saved further program II moved to the next memory line, so that the first memory line for the second line of the other to be stored Program II has become free again. This moving the individual Memory lines is made until the first saved line has arrived in the last memory line. Then there is a full

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permanent image of the further program II in the memory. Line by line Shift is advantageously carried out by parallel transmission, however, it can also be done by serial transmission.

The saved image can now be controlled by a corresponding sequence control can be displayed on the picture tube. During the display time of the image of the further program II on the picture tube, the memory contents circulate continuously in the memory.

• As a simplification, the same memory content can be shown in both partial images with a deliberate decision not to use a higher resolution due to the interlaced image. This is possible because the resolution is in the vertical direction still remains in the order of magnitude of the horizontal resolution. By this measure can halve the number of storage spaces required.

From the consideration that the speed of movement of one in program I shown object, e.g. B. .. of a soccer ball, in the image section further Program II need not be larger than in program I, it follows that the number of new images to be stored in the further program II is proportional can be reduced to the reduced scale. This results in the advantage that the disturbance of the program I caused by the switching of the tuner required for storing is greatly reduced.

The switching part of the memory and switching stage 11 is also designed so that during each scrolling of the program I with n / m lines further Program II, where η is the number of lines of the reduced image of the further program II and m is the number of memory runs which is chosen for the renewal of the entire memory content (the number m can also be = 1, for example).

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Both programs (I and II) should be freely selected from the existing transmitter and Program offer can be selected, so that in general both programs are controlled by different clocks. Through this but get the individual lines to be saved of the further program II in any memory locations of the memory, d. H. de * start of line and that

End of line no longer matches the beginning and end of the corresponding Memory line. For a meaningful reproduction, this should therefore be avoided. which can be achieved by letting the information contained in the corresponding memory cell circulate until the line sync pulse appears at a certain point, e.g. at the end of the memory line. Since the image sync pulse of the reduced image with the of the picture from program I is not in phase, an assignment is also required here. A simple picture pulse search circuit derived from a standard Pulse separation circuit can exist with an integration element, controls the storage each line to be stored in the memory lines provided as soon as the image sync pulse is detected in a specific memory line has been.

The memory can advantageously be memory according to the type of known Charge shifting circuits are used, for example Bucket chain circuits, charge-coupled components or the like. Particularly advantageous is the memory described in the earlier application P 24 30 349. 9-53.

It is easily possible to use the picture shown in the other program Π as a standing image to show the current program in certain Time intervals is taken, whereby the memory control can be simplified. In this case, however, the further program II movement information contained, but depending on the evaluation and the dem. attention paid by the viewer to further program II is of minor importance. .

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The present invention thus relates to a television receiver with a screen on which a selected first program is displayed, and with a device by means of which at the same time another program can be played on the same screen, according to patent .... (patent application P 24 13 839.4), wherein the device for reproducing the further program consists of an arrangement in the television set, which is in a Image section of the first program reproduced on the screen, at least one image section of the further program makes visible and contains a memory in which the image content to be reproduced of the further program with reduced number of lines is first saved and then in the corresponding position of the line of the first program to display the next Program is called up line by line, with a common signal path for the simultaneous playback of both programs (Tuner, IF amplifier, video amplifier) is used and a switching part the tuning means of the tuner during the lines to be stored of the picture of the further program from the reception frequency of the first program switches to that of the next program.

As further research has shown, the switching causes of the tuner and the IF amplifier to the further program II Interference in the audio channel, d. H. The useful signal emitted by the device loudspeaker is superimposed by an interference signal that is at least contains the frequency of the tuner switching signal.

The object of the invention is therefore to suppress to specify suitable circuits for this interfering signal. These are characterized in the claims and are based on the further Figures of the drawing explained in more detail together with advantageous embodiments.

Fig. 3 shows the principle circuit diagram of a from f EADERSHIP form a first solution path for the underlying object of the invention,

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Fig. 4 shows the course of the input and output voltage in the arrangement according to Fig. 3,

FIG. 5 shows the basic circuit diagram of an exemplary embodiment of a second approach to the one on which the invention is based Task,

FIG. 6 schematically shows curve shapes of various voltages occurring in the arrangement according to FIG. 5,

Fig. 7 shows the basic circuit diagram of an embodiment of a third approach to the problem underlying the invention and

FIG. 8 schematically shows waveforms of voltages occurring in the arrangement according to FIG. 7.

The three possible solutions to the problem on which the invention is based, which are to be explained with reference to the figures, are based on the knowledge that the narrow-band tone IF filter that is present in conventional televisions, mostly in the form of a ceramic filter to filter out the audio intermediate frequency signal, its frequency in the CCIR television standard is known to be 5.5 MHz and in the USA standard is 4.5 MHz, to the tuner switching that takes place during a line at the end of the line a transient response that z. B. lasts about a further line duration. The audio signal is therefore for a time approximately the sum of the duration of the square-wave pulses switching the tuner 3 and the settling time of the audio IF filter is the same, disturbed and superimposed by the overshoot signal of the tone IF filter. This time is hereinafter referred to as the total disturbance duration T. designated.

In FIGS. 4, 6 and 8, large letters are used to mark the individual ones in connection with the first shown in FIG. 6a Square pulse occurring curves. The Sicrnalwert appearing at the beginning of this disturbance in the audio signal is with F and

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the signal value occurring at the end of this disturbance is denoted by G.

In the first solution according to the invention, which is based on FIG. and FIG. 4 will now be explained, the last one which is just occurring before the start of the switchover of the tuner 3 to the further program II Signal value F of the audio signal NF for the total disturbance duration T is stored by means of a sample-and-hold circuit and for this time fed to the audio output amplifier instead of the audio signal.

In the exemplary embodiment of this solution shown schematically in FIG. 3, the audio signal NF passes through a special one Operational amplifier which is operated as a sample-and-hold circuit for the total duration of the disturbance T by means of appropriate wiring will. For this purpose, the operational amplifier 12 has the input c, via which the output resistance can be electronically controlled and its voltage gain is set to one by means of the resistor R31. The negative feedback resistor R31 couples the output signal of the operational amplifier 12 to the inverting input e back, the output signal not directly at the output a of the operational amplifier 12, but at the Working resistance R32 of the impedance converter connected downstream of output a is connected, which in the exemplary embodiment according to FIG. 3 consists of the field effect transistor operated in a source follower circuit T31 with the drain resistor R33 exists.

The capacitor C31 is located between the output a of the operational amplifier 12 and the circuit zero point. The initial resistance of the operational amplifier 12 influencing input c is operated as a switch via the emitter circuit Transistor T with collector resistor R34 from a value as small as possible when operating as an operational amplifier to one as high a value as possible when operating as a sample-and-hold circuit. The operational amplifier is connected to the inputs b, d

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to the poles of the operating voltage _{source U R} , the minus pole of which is connected to the circuit zero point.

The duration of said switching is equal to the overall fault duration T.Zur generating pulses of this duration in the exemplary embodiment according to FIG. 3, the pulse shaper 13 / which may be realized for example as a monostable multivibrator is provided, whose input E ¹ supplied to the tuner 3-switching rectangular pulses and at its output, which is connected to the base of the transistor T, the pulses with the total duration of the disturbance T occur.

The audio signal NF is the non-inverting input e of the operational amplifier 12 via the input E of the sample-and-hold circuit supplied, while the "compensated" audio signal NF 'via the output A at the source resistor R32 of the field effect transistor T31 is removed.

The curves shown in FIG. 4 illustrate the course of the input voltage U and the output voltage U _{a of} the arrangement according to FIG. IF filter is superimposed. This waveform is shown in Fig. 4a. The total interference duration T is made up of the duration t of the square-wave pulse switching the tuner 3 and the settling time t _{f of} the audio IF filter: T = t + t _f .

The output voltage U shown in FIG. 4b does not contain the interference pulse contained in FIG. 4a; The curve of the output signal U _A therefore "jumps" at the end of the disturbance to the signal value G then occurring in the audio signal.

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For simple audio reproduction that does not place particularly high demands on the sound quality, that is explained with reference to FIGS. 3 and 4 first solution of the problem underlying the invention is sufficient. A sound quality that is higher than this solution can now be explained with the aid of FIGS. 5 and 6, the second solution on which the invention is based Accomplish task. This second solution also uses a sample-and-hold circuit, but avoids that in FIG. 4b "jump" of the audio signal occurring at the end of the interfering signal. In the arrangement shown in FIG. 5, this is achieved by that by integrating the signal value F of the audio signal NF present at the beginning of the disturbance to the end of the disturbance occurring signal value G is raised or lowered.

In this case, the disturbed audio signal NF runs through the delay line 14, for its implementation customary and known delay lines can be used, so for example glass delay lines, according to the principle of charge transfer circuits working delay lines, especially bucket chain circuits, etc .. The delay time t the delay line 14 is to be selected to be equal to the total disturbance duration T.

Furthermore, the signal value G of the audio signal NF appearing at the end of the delay time of the delay line 14 at its input is stored for the total disturbance duration T by means of the sample-and-hold circuit 15. An arrangement as shown in FIG. 3 can be used to implement this sample-and-hold circuit. However, the square-wave pulses switching the tuner 3 are not to be fed directly to the input E ^{1 according to FIG. 3;} Rather, these are first to be delayed by the total disturbance duration T in a delay arrangement.

The delay circuit 14 is finally the operational control

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stronger 16 connected downstream, in which at the end of the delay time t on the one hand the resistor R51 in front of its input from the output of the delay line 14 to the output of the sample-and-hold circuit 15 and on the other hand the capacitor C51 of constant potential to the non-inverting input of the operational amplifier: 16 for the total disturbance duration T and the negative feedback resistor R52 is switched off.

In the exemplary embodiment according to FIG. 5, the disturbed audio signal NF of the delay line 14 becomes capacitive via the capacitor C52 supplied and removed from it capacitively via the capacitor C53. By means of the integrator R54, C54 the DC voltage component of the audio signal NF is obtained and on the one hand, via the resistor R53, the audio signal delayed in the delay line 14 after the capacitor C53 and. on the other hand fed directly to the non-inverting input of the operational amplifier 16.

The above-mentioned switching of the capacitor C51 and the output of the delay line 14 and the disconnection of the resistor R52 is made in the schematic representation of FIG. 5 _r using the drawn as a mechanical switch switches S51 S52, S53. It goes without saying, however, that these changeover switches are expediently designed as electronic switches in a circuit to be implemented. Through the dashed line leading to input E ^1. The line indicates that these switches are actuated during the same times during which the signal controlling the sample-and-hold circuit 15 is present at this input.

In Fig. 6 there are various waveforms of voltage profiles

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shown as they occur in the arrangement of FIG. In FIG. 6a, the voltage U of the square-wave pulses switching the tuner 3 is shown the duration t shown. As can be seen, the tuner is switched in this example every fifth line of a television picture.

FIG. 6b shows the voltage U _{1 present} at the input E, ie the disturbed audio signal NF, the disturbance already shown in FIG. 4a being superimposed on the audio signal NF for the total disturbance duration T. Fiq. 6c shows the input voltage U n, with the course of the square-wave pulses fed to this input, the duration of which is equal to the total disturbance duration T and which are delayed by the same duration T compared to their beginning.

FIG. 6d shows the output signal U of the delay line 14, which differs from the input signal U _F shown in FIG. 6b only in that it is delayed by the delay time χ given the same curve shape.

6e shows the output voltage at the output H of the sample-and-hold circuit 15. The signal value G occurring at the end of the disturbance is constant for the duration T and then "jumps" to the signal value G ¹ currently present.

Finally, FIG. 6f shows the voltage UL at the output A of the on-order according to FIG. 5, that is to say the course of the "compensated" audio signal NF '. Compared to Fig. 6e it can be seen that the there "Jump" is replaced by a continuous transition.

By means of the delay line 14 it is first achieved that the signal values F, G of the audio signal NF occurring at the beginning and at the end of a disturbance equal to the end of this disturbance.

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are available in good time, see Fig. 6e, f at the end of The operational amplifier operating in normal amplifier mode in the switch position shown for changeover switches S51, S52, S53 16 at the end of the disturbance, the point in time at which the signal value F occurring at the beginning of the disturbance at output A of the audio signal NF is switched to integrator mode. From the switching point onwards, the sample-and-hold circuit 15 holds the at the end of the disturbance occurring signal value G of the audio signal NF fixed to its value, so that the at the beginning of the disturbance occurring signal value F charged capacitor C51 is charged via the resistor R51 to the signal value G at point H. or discharges.

FIGS. 7 and 8 relate to a third possible solution of the problem underlying the invention. In the implementation shown schematically in FIG. 7, this solution runs through the disturbed audio signal NF the electronic delay line EK based on the charge transfer principle, whose Delay time t is equal to the total disturbance duration T and at which the frequency f of their clock signals P1, P2 is above the audibility limit. Between input E and output A. the electronic delay line EK is connected to a voltage divider that has as many taps as the delay line Has stages, each tap of the voltage divider at the end of the total disturbance duration T briefly with each stage the delay line EK is connected with direct current.

The delay line shown in the embodiment of FIG EK is structured according to the bucket chain principle; however, all other known types of charge transfer can also be used based delay lines can be applied. Each stage of the delay line EK consists of one

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Insulating layer field effect transistor, which is located with its controlled current path in the signal path, and a capacitor located between its control electrode and the point of the main current path facing away from the entrance. In Fig. 7, six such stages, namely stages 71, 72, 73, 74, 75, 76, are shown. The insulating layer field effect transistor T77, which is the last on the right in FIG. 7 and in which the mentioned capacitor is replaced by a galvanic connection, serves to terminate the line in terms of direct current. The insulating-layer field effect transistor T70, shown first on the left in FIG. 7, and the capacitor C70 assigned to it, one pole at the circuit zero point, as well as the series capacitor C71 following input E and the _{resistor R70 connected to the DC bias voltage U Q} are used to couple the audio signal NF.

The odd-numbered stages 71, 73, 75 are via the control electrodes of the respective insulating layer field effect transistors fed with the clock signal P1 shown in Fig. 7, during the the even-numbered stages 72, 74, 76 the clock signal P2 is supplied in the same way.

As is generally the case with bucket chain circuits, the clock signals P1, P2 are rectangular and have the amplitude U_ as well as the frequency f. The two clock signals P1, P2 are so offset in time that the effective impulses of one signal occur in the pauses of the other.

The frequency £ "of the clock signals, the number of stages η and the delay time ti obey the condition for bucket-chain circuits:

* b * = Ti- or n =:

From the above requirement that the frequency f above the audibility limit is (> 20 kHz), and with a value of 120 μs for the total disturbance duration T, this results in a mini

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times the number of stages η. = 5 and a clock frequency f. = 20.8 kHz.

In the exemplary embodiment shown in FIG. 7 with n = 6, a value of fp = 25 kHz of the clock frequency results when * fc = 120 us again.

The point closer to the input of the main current path of the insulating layer field effect transistor each stage is via the main current path of a corresponding further insulated gate field effect transistor T71, T72, T73, T74, T75, T76 each with a tap of the the resistors R70, R71, R7 2, R73, R74, R75, R76 existing ohmic voltage divider connected. The resistor R70 is on Via the impedance converter 16, that is to say for example via an emitter follower or source follower stage, at the DC voltage level Input of the delay line EK, that is to say at the input of the insulating layer field effect transistor T70. The resistor R76 is connected to the output A via the impedance converter 17, which is in principle identical to the impedance converter 16. The voltage divider resistors R7O .... R76 preferably have the same resistance value, so that the taps are voltage equidistant.

The difference between the and the voltage divider is therefore always present at the beginning of the delay time and at the end of the delay time occurring signal values F, G. This property is now exploited according to the invention by at the end of the total disturbance period T, based on the beginning of a fault, is a narrow one

Pulse is generated, which the transistors T71 T76 momentarily

conductively controls and at this point in time at the taps of the voltage divider lying potential thus into the

individual stages 71 76 of the delay line EK on -

feeds. This brief pulse is fed to input X and can be easily adjusted by means of a pulse shaper and delay circuit can be generated from the square-wave pulses switching the tuner 3.

FIG. 8 schematically shows some waveforms as shown in FIG

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Arrangement according to FIG. 7 occur. 8a and 8b correspond to FIGS. 6a and 6b, ie they show the square-wave pulses of duration t switching over the tuner 3 as well as the disturbed audio signal NF at input E. The course of FIG. 8c corresponds to the curve of FIG. 6d, ie the signal according to FIG. 8b is delayed by the delay time f of the electronic delay line EK. 8d shows the voltage U of the narrow pulses to be applied to input X. Finally, FIG. 8e shows the output voltage U ₇ . with the stepped approach of the signal value F present at the beginning of a disturbance to the signal value G occurring at the end of the disturbance.

In all three approaches according to the invention, it is useful the "compensated" audio signal NF ', before it is fed to the audio output stage, still to pass through a low-pass filter in order to pass the

to suppress interferences superimposed on the various switchover and clock signals. The upper limit frequency of this low pass is advantageously lower than the frequency of the square-wave pulses switching the tuner.

10 patent claims

5 sheet drawing with 8 figures

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Claims (1)

Fl 861 P.M. Flamm et al 4-4 PATENT CLAIMS TV receiver with a screen on which a selected first program is played, and with a device by means of which another program can be played on the same screen at the same time, according to patent (patent application P 24 13 839.4), the device for playing the other program consists of an arrangement in the television set, which makes at least one image section of the further program visible in an image section of the first program reproduced on the screen and contains a memory in which the image content to be reproduced of the further program is first stored with a reduced number of lines and then in a corresponding format Position of the line of the first program to display the next program is called up line by line, with a common signal path (tuner, IF amplifier, video amplifier) also serving for the simultaneous playback of both programs and a switching part for the tuning means of the tuner during the lines of the image of the further program to be stored switches from the reception frequency of the first program to that of the further program, characterized in that the last signal value (F ) of the audio signal (NF) for a time which is approximately equal to the sum of the duration (t) of the square-wave pulses switching the tuner (3) and the settling time (t _f ) of the audio IF filter, the total interference duration (T) j is stored by means of a sample-and-hold circuit and fed to the audio output amplifier instead of the audio signal for this time. -20- 7098U / 0384 Fl 861 P.M. Flamm et al 4-4 2. Television receiver according to claim 1, characterized in that the audio signal (NF) has an operational amplifier (12) with an electronically controllable output resistance and a set voltage gain of one, that the output (a) of the operational amplifier (12) is permanently connected to a capacitor (C31) and that the output resistance from as small as possible to as large as possible for the total duration of the disturbance (T) is switched. 3. TV receiver according to claim 2, characterized in that that the switching signal (U ₅₁₁ ) for switching the operational amplifier from the lowest possible to the highest possible output resistance from the square-wave pulses switching the tuner (3) is generated by means of a pulse shaper circuit (13). 4. TV receiver with a screen on which a chosen one first program is played, and with a facility by means of which at the same time another program on the same Screen can be reproduced according to patent .... (patent application P 24 13 839.4), the device for reproduction the further program consists of an arrangement in the television set, which is shown in an image section of the first program reproduced on the screen makes at least one image section of the further program visible and Contains a memory in which the image content to be reproduced of the further program with a reduced number of lines initially is saved and then in the corresponding position of the line of the first program to display the next -21- 7098U / 0384 Fl 861 P.M. Flamm et al 4-4 Program is called up line by line, with a common signal path (tuner, IF amplifier, video amplifier) also serving for the simultaneous playback of both programs and a switching part the tuning means of the tuner during the lines to be stored of the image of the further program from the reception frequency of the first program switches to that of the further program, characterized in that the audio signal (NF) runs through a delay line (14), the delay time ('p) of which is approximately the sum of the duration (t) of the square-wave pulses switching the tuner (3) and the settling time (t _f ) of the tone IF filter is equal to the total interference duration (T). is the same that the signal value (G) of the audio signal (NF) occurring at the input of the delay line (14) for the total disturbance duration (T) by means of a sample-and-hold circuit at the end of the delay time (tr), based on the start of a tuner switchover pulse (15) is stored that the delay line (14) is followed by an operational amplifier (16) in which at the end of the delay time Cb) a resistor (R51) located in front of its inverting input from the output of the delay line (14) to the Output of the sample-and-hold circuit (15) and a capacitor (C51) connected at one end to the output (A) of the operational amplifier (16) is switched from constant potential to the inverting input of the operational amplifier (16) for the total disturbance period (T) and a negative feedback resistor (R52) between the output (A) and the inverting input is also disconnected for the total duration of the disturbance (T). 5. Television receiver according to claim 4, characterized in that the sample-and-hold circuit (15) consists of one with his 709814/0384 Fl 861 P.M. Flamm et al 4-4 Input connected in parallel to the input of the delay line (14) Operational amplifier (12) with an electronically controllable output resistance and a set one Voltage gain of one, the output of which (a) is permanently connected to a capacitor (C31) and its output resistance from as small as possible to as large as possible for the total duration of the disturbance (T) is switched. Television receiver according to claim 4 or 5, characterized in that that the non-inverting input of the operational amplifier (16) the mean DC potential of the undelayed Audio signal (NF) is supplied and that only the alternating component of the audio signal (NF) passes through the delay line (14). Television receiver with a screen on which a selected first program is played, and with a device, by means of which another program can be played back on the same screen at the same time, according to patent (patent application P 24 13 839.4), whereby the device for reproducing the further program from an existing in the television set Arrangement consists of at least one image section of the first program displayed on the screen makes an image section of the further program visible and contains a memory in which the image content to be reproduced of the other program with a reduced number of lines is initially saved and then in corresponding The position of the line of the first program for displaying the further program is called up line by line, furthermore -23- 709814/0384 Fl 861 P.M. Flamm et al 4-4 is a common pathway for the simultaneous reproduction of the two programs (tuner, IF amplifier, video amplifier) and a switching part to be stored, the image lines of the other program on the switching the tuning of the tuner during the reception frequency of the first program of the other program, characterized characterized in that the audio signal (NF) runs through an electronic delay line (EK) based on the charge transfer principle, the delay time {χ) of which is approximately the sum of the duration (t) of the square-wave pulses switching the tuner (3) and the settling time (t _f ) of the tone IF filter is the same, the total interference duration (T) _{f is the} same and at which the frequency (f) of its clock signals (P1, P2) is above the audibility limit that between the input and the output of the delay line (EK) a voltage divider is connected which has as many taps as the delay line has stages, and that each Tapping of the voltage divider at the end of the total disturbance duration (T) is briefly connected to a corresponding stage (71 ... 76) of the delay line (EK) in direct current. 8. television receiver according to claim 7, characterized in that that an ohmic voltage divider (R7O R76) is used and its taps via insulating-layer field-effect transistors operated as switches (T71 T76) briefly with the corresponding stages (71 76) of the delay line (EK) are connected. 9. Fei ^ sehempfanger according to claim 7 or 8, characterized in that that the voltage divider has an impedance converter (16, 17) each with the input and the output of the 709814/0384 -24- Fl 861 P.M. Flamm et al 4-4 delay line (EK) is connected. 10. Television receiver according to one of claims 1 to 9, characterized in that the "compensated" audio signal (NF ¹ ) is fed to a low-pass filter, the upper limit frequency of which is smaller than the frequency of the square-wave pulses switching the tuner (3). 7098U / 0384