DE3305961C2 - Color television signal processing apparatus for use with a reproducing unit for video information recorded according to the PAL television system - Google Patents

Abstract

A device for processing a PAL color video signal from a video information playback unit is described with a PAL phase converter for converting the PAL phase of a frequency component of a color carrier signal and a color burst signal and with a switching device for selecting either an applied color carrier signal or the output signal of the PAL phase converter. The switch is controlled in such a way that it selects the output signal of the PAL phase converter in the transition period from normal playback from the playback unit to a special playback mode. A generating device for an additional jump operation signal is provided so that an additional jump operation takes place if the number of occurrences of the recording track jump operations is odd during the special playback mode.

Description

The invention relates to a color television signal processing apparatus for use with a display unit for video information recorded according to the PAL television system with normal playback operation and a special display mode, with a color carrier signal phase compensator connected to the display unit with a separator device for transmitting the chrominance component of the scanned color video signal, with a phase converter connected to the separator for inversion the PAL switching phase of the chrominance component, with a first switch to select either the Output signal of the separator device or the output signal of the phase converter and with an adding device for the output signal of the first switch and the luminance component of the output signal of the Playback unit, a second switch for selecting either the output signal of the playback unit during normal playback operation or the output of the adder during special playback mode, and with a control device for controlling the switching state of the first

Switch in such a way that the continuity of the PAL switching phase is maintained during the transition from normal operation to special operation and vice versa, the control device switching the first switch back and forth between the output signal of the phase converter and that of the separator device depending on jump command signals during the special playback operation.
Composite color video signals according to the PAL system are characterized in that one of the color signals changes its phase per horizontal line. Therefore, in television receivers according to the PAL system, it is necessary to change the phase of a subcarrier signal which corresponds to one of the color difference signals at each line. In order to correctly determine the phase reversal of the subcarrier signal, the PAL system television receiver is generally equipped with a burst signal phase discriminator which is used to discriminate the phase reversal of the color burst signal which indicates the phase of the color difference signal. Furthermore, the burst phase discriminator is generally equipped with a time constant characteristic in order to prevent a rapid response to noise signals.

On the other hand, various video playback systems, e.g. B. video tape recorder or video disc player systems used as video information sources for a playback system. With these systems

there are various special playback modes, for example still image playback, line zoom playback, Time-lapse playback at doubled or tripled playback speed, etc. For video disc players (VDP) there is also a fast scanning method in which the scanning device radially over the video disk is driven to search the information recorded on that disk.

During playback of video signals in these special playback modes or in this The scanning mode is a jump mode; H. the movement of the recording or scanning point from a recording track to another is necessary so that the required recording tracks can be followed can. In known systems for reproducing recorded color TV information, however, there is Disadvantage that the phase reversal of the subcarrier signal by the jump operation during a special Playback process can be disturbed, and the same disturbance also when transitioning between the normal reproduction process and the special reproduction process and during the scanning process occurs in the VDP system

A color television signal processing apparatus of the above-mentioned artist is known from US-PS42 36 173 at this known processing device, a special control device is provided that both the control command for the switchover, the control command for the jump process, the control command for the mixing of the phase-shifted Color carrier signal and also the control command for the phase position is generated. This results in significant restrictions with regard to a more free selection of the passage of time in slow-motion or fast-motion playback, and also in this known device is unfavorable that the field of application by the existing need to scan an entire image cycle at a time. is severely restricted.

The invention is based on the object of providing a color television signal processing device as defined at the outset Kind of so that when scanning with the help of all known recording media, especially with video disc players of the most varied types and with all types of playback, in particular still image, Slow-motion, time-lapse and search playback reproduce color-correct playback using the PAL method is possible.

To solve this problem, it is provided that the control device immediately switches to the second switch Occurrence of a special playback mode signal switches to the output of the adding device and at the same time puts the first switch on the output signal of the separator device and that the first switch at Occurrence of the next jump command signal is switched.

In this way it is possible without a temporal link to the jump command in the special playback mode to ensure the correct phase position of the color subcarrier bursts with the return line pulse. The free availability over the time at which the jump commands occur enables a more free selection of the Lapse of time in slow-motion or fast-motion playback.

According to a further development of the invention, a device is provided for generating an additional recording track jump command signal if the number of recording track jump command signals is odd during the special playback mode. Dadu ^r ch is increased security against a color reproduction failure in the return of the special playback mode to the normal playback mode.

According to a further embodiment of the invention, there is a device connected to the separator device for detecting a change in a PAL phase change state of the color burst signal before and after at a certain point in time and for generating a control signal according to the result of the detection process intended.

In this way it is possible to determine whether there is before or after a certain, usually the Jump time corresponding time the phase state of the color carrier burst signal changes, and im If such a change is detected, the control signal is then generated. Another embodiment The invention is characterized in that the device for detecting the phase change is as follows Components includes:

a color burst signal phase converter for phase conversion of the color burst signal with each horizontal line sequence,

a subcarrier signal generator for generating a subcarrier signal from the color burst signal, a Multiplier means for multiplying the output signal of the color burst phase converter by a Signal whose frequency and phase are equal to the frequency and phase of the subcarrier signal to Creation of a DC voltage component which characterizes the phase change state of the color burst signal and

a control signal generator for generating the control signal in accordance with that generated by the multiplier device obtained DC voltage component.

To generate the control signal, a direct current component of the color burst signal and the derived subcarrier signal formed mixed signal used, whereby the generation of the control signal much simplified.

The invention is explained in more detail below with reference to the drawing, for example; in this shows eo

F i g. 1 is a vector diagram of a color carrier signal in a PAL system,

F i g. Fig. 2 is a schematic representation of a portion of recording tracks with the relationship between the path of the recording device and the recording tracks in special playback mode,

F i g. 3 is a block diagram of an embodiment of a color signal processing circuit of a video disc player;

F i g. FIGS. 4A to 4E show timing diagrams of operations of the circuit according to FIG. 3 that without application of the present invention occur in the transition from normal playback to special playback can.

F i g. 5A to 5E timing diagrams similar to FIG. 4 of transitional phenomena without application of the invention can occur during a transition from special playback to normal playback,

6 shows a block diagram of an embodiment of the color signal processing device according to the invention for connection to the control terminals of the switches 55 and 6 from FIG. 3,
F i g. 7 shows a timing diagram for the operation of the circuit according to FIG. 6,

F i g. 8 is a block diagram of a color signal processing circuit of a color receiver according to the PAL system,

9 shows a timing diagram with the phase properties of a color burst signal during the scanning operation,

F i g. 10 is a block diagram of a second embodiment of a color signal processing device according to the invention,

F i g. 11A to 11E timing representations of the operation of the circuit according to FIG. 10, and

F i g. 12A to 12E timing diagrams similar to those in FIG. 11A to 11E for the operation of the circuit according to FIG. 10 with one compared to FIG. 11 phase-inverted color burst signal.

Before explaining the preferred embodiments of the processing device according to the invention, it should first the color video signal according to the PAL system will be explained in detail.

In general, the color video signal Ep according to the PAL system is expressed by the following equation (1):

Ep = Y + (B- Y) sin ω * ΐ ± (RY) cos eo _s t (1)

where V is the luminance signal, β is the blue signal and R is the red signal, and w _{s is} the angular frequency (4.43 MHz) of the subcarrier signal.

The sign ± in equation (1) means the phase change with each line sequence. Therefore, a component R - K of the color carrier signal is generated by amplitude modulation of the subcarrier signal (cos eo _s t) , which changes its phase by 180 ° for each horizontal line. The color burst signal accordingly also represents information that is used in a receiver system to exchange the subcarrier signal for demodulating the phase position of the R- V component in each line. Therefore, as the vector diagram in FIG. 1 shows that the color burst signal is in the form of a signal sin (co _s t ± 135 °) deviating from the B-Y axis by + 135 ° in each horizontal line (the broken line in FIG. 1 will be explained later) .

In order to accurately reproduce the color from the video signal of the PAL system at the receiving end, it is necessary to invert the subcarrier signal of the R- V component every other line in accordance with the phase detection of the color burst signal. For this purpose, a burst phase discriminator is provided in order to distinguish the phase of the color burst signal. If the phase conversion of the subcarrier signal takes place opposite to the correct phase conversion and leads to the reproduction of a negative phase signal - (R- > 9, a circuit for converting the subcarrier signal is reset so that the correct demodulation is then effected.

However, if the burst phase discriminator responds too quickly, any noise will become a component in the color video signal lead to the generation of a reset pulse, which of course is not desirable. To that kind of To avoid malfunction, a time constant is generally set so that the reset pulse signal only is generated when the demodulation of the negative phase signal over more than a predetermined This providing a time constant characteristic is in the reception of television broadcast signals very effective. However, if a receiver with this time constant characteristic is used in the If an image is used that comes from a video disc player (VDP), a later result will result explanatory disadvantage.

In addition to normal playback operations, various specials are also available with the VDP system Types of playback possible, e.g. B. Still playback, slow motion playback, time lapse playback with double and triple speed etc. During the operation of these special types of playback it is necessary to perform a so-called jump process, in which the playback point of the recording device is transferred from one recording track to the next.

In Fig. 2 shows, for example, the path of a playback point of the recording device during the still image mode. As the dashed line 1 shows, the recording point changes from the recording track 3 to the recording track 2. Each section of the recording tracks 2 and 3 corresponds to one horizontal line. In the case of an optical disk with constant angular velocity (CAV), the sections of the recording track for each horizontal synchronization signal, i.e. the boundaries of each section in the radial direction of the optical disk are aligned in adjacent recording tracks.This is a PAL phase, i.e. the phase of the signal (R - Y ) cos <a _s t determined in the manner shown in such a way that it is different, i.e. inverted, in each adjacent recording track Color killer circle off, because the response of the burst phase discriminator (the PAL phase discriminator) is delayed because of the time constant characteristic

In order to avoid this disturbance during a jump process, the VDP video disk player is equipped with a device shown in FIG. 3 circuit shown
According to FIG. 3, a played color video signal is fed to a delay circuit 4 and a PAL phase compensator (color carrier signal phase compensator) 5. An output signal A 2 of the delay circuit 4 and an output signal as 2 of the PAL phase compensator 5 are applied to a second switch 6 whose output has a phase compensator connected to a display or playback system Band-pass filter (BPF) 51 and a low-pass filter (LPF) 52 for separating the color carrier signal and the luminance signal. That

Bandpass filter 51 only picks up frequency components of the color carrier signal. After passing through a PAL phase inverter7, consisting of a multiplier circuit 53 and a bandpass filter 54, its output signal is applied as input signal B 1 to a first switch 55, to which the output signal of bandpass filter 51 is also applied directly as input signal A 1. The output signal of the first switch 55 is added to the luminance signal from the low-pass filter 52 in an adder circuit 56, whereby the output signal B 2 of the PAL phase compensator 5 results. A subcarrier signal generator 8 is provided which picks up only a color burst component from the output signal of the bandpass filter 51 and generates a subcarrier signal cos ca _s l at the same frequency as that of the color burst signal. The output signal from the subcarrier signal generator 8 is then fed to a frequency multiplier 9 which generates a signal cos 2 w _s t. This signal is then fed to the multiplier circuit 53 as a multiplier signal for the output signal of the bandpass filter 51. In this way, the phase inversion of the PAL signal is achieved by means of a so-called "heterodyne conversion".

In particular, the output signal of the multiplier circuit 53 can be expressed according to equation (2) if the color carrier signal including the color burst signal is expressed as sin (<y _s f + Φ) :

cos 2 co _s t ■ sin (co _s t + Φ) =

(3 co, t + Φ) + sin (« ₅ ί - Φ) \

A fundamental wave component is selected by means of the bandpass filter 54 in order to obtain a signal sin {co _s t - Φ) ζν . With respect to the B - K component of the chrominance carrier signal, the phase remains unchanged since the value! ^ Is equal to zero (see FIG. 1). Conversely, the R - K component is phase inverted because the value ^ is equal to ^ r / 2.

In other words: The R - Y component of the output signal of the bandpass filter 54 is determined by sin (fi) _s t - λτ / 2) in contrast to the component of the input signal, sin (<y _s f + λτ / 2) of the PAL Phase converter 7. As for the color burst signal (Φ = ± 135 °), the output signal of the bandpass filter 54 is sin (cüst ± 135 °) with respect to the color burst component sin (a _s t + 135 °) of the input signal to the PAL phase converter 7 inverted in phase In this way, the PAL phase conversion is carried out. Instead of the heterodyne conversion system, a glass delay line or other known circuit can be used.

With this arrangement, the second switch 6 is controlled during normal playback operation to select the signal A 2 in order to bypass the PAL phase compensator 5 and eliminate the signal deterioration. In addition, the delay line 4, which provides a delay corresponding to the delay characteristics of the PAL phase compensator 5, can be omitted.

During the special playback mode, for example the still image mode, the second switch 6 is controlled in such a way that it receives the signal B 2 from the PAL phase compensator 5. The first switch 55 is operated with each occurrence of a jump in such a way that it alternately selects one of the signals A 1 and B ϊ one after the other. In this way, the phase change state of the PAL signal is correctly maintained even when the jump is made.

However, since the second switch 6 can be operated without any relation to the position of the first switch 55, the phase change state of the PAL signal can be discontinuous even when the second switch is operated will. Since the PAL phase discriminator of the playback system to be connected to this circuit, the has the time constant characteristic already mentioned, such a discontinuity of the phase change state results a malfunction of the color rendering and / or the commissioning of the color killer circuit.

This problem is illustrated in detail with reference to FIGS. 4 (4A to 4E) and 5 (5A to 5E) explained below. 2 takes place with each revolution of the optical disc, ie the track point or playback point jumps from a line π + 4 of track 3 to line π + 5 of track 2. In FIG. 4A shows the level of a playback mode signal for controlling the second switch 6, namely the second switch 6 is switched away from the normal playback operating position F i g at the time f 1. 4B now shows the jump signals which are used as trigger signals for a flip-flop to generate a control signal for the first switch 55. FIG. 4C shows the switching between the signal A 2 and B 2. FIGS. 4D and 4E show the switching state of the first switch 55, which selects one of the two input signals A 1 or B 1 as an alternative. These are the two types of switching sequences of the first switch 55 in FIG. 4D or 4E shown as a function of the initial position of the first switch 55. If F i g. 4D holds, the continuity of the PAL phase change is maintained since the first switch 55 sends the inverted Signal! B 1 of the PAL phase converter 7 selects. In the case of the FIG. 4E, however, the first switch 55 selects the non-inverted signal A 1 of the PAL phase converter 7 during the first jump operation. This reverse state of the PAL phase change also continues in the subsequent operation of the first switch 55. So in the case of FIG. 4E, the color reproduction of the display system (on the right in FIG. 3) is disturbed, at least for a few fields after the jump process.

In the same way, the operation in the transition period from the special reproducing operation to the normal reproducing operation becomes with reference to FIG. FIGS. 5A to 5E explain FIG. 5A to 5E correspond to the lines denoted by the same letters in FIG. 4. As in the previous case, two types of switching sequences of the first switch 55 are again possible. In the switching sequence shown in FIG. 5D, the continuity of the phase change of the PAL signal is maintained, since the non-inverted signal A 1 is selected by the first switch 55 just before the second switch 6 is actuated at time 1 3 However , the switching sequence shown on line SE is the phase change state of the PAL signal at time t3 reversed. This reversed phase change state creates the same problem as in the previously explained process.

A first embodiment of the color signal processing device according to the invention will now be described with reference to FIG. 6th shown in Fi g. The circuit shown in FIG. 6 generates the signals for controlling the first switch 55 of the circuit shown in FIG F i g. 3 circuit shown. The playback mode signal, which is used to control the second switch 6 in the

(2) 15

20th

35

40

45

50

55

60

Circuit according to FIG. 3 is used at the same time to a terminal a of the circuit in FIG. 6 created. This reproduction mode signal then comes via an inverter 10 to an input terminal of an OR gate It (negative logic). A jump time signal is applied to the other input terminal of the OR element 11, and its output signal is applied to a flip-flop 12 and an AND element 13. An inverted reproduction mode signal is fed to the flip-flop 12 as a clear signal. The Q output signal of the flip-flop 12 is used as a trigger signal for a monostable multivibrator MMV14 and as a control signal for the first switch 55 of the circuit from FIG. 3 used The Q output signal of the MMV 14 is fed to an OR gate 15 which simultaneously receives the playback mode signal. The output signal of the OR element 15 is applied as a signal / to another input of the UN D element 13, the output signal of which is used as a jump signal g .

ίο The operational sequence of the circuit according to F i g. 6 will now be explained on the basis of the timings TA to TG . In each of these lines, the signal status is shown at the positions in FIG. 6 shown.

It is assumed here that the first and second switches 55 and 6 respectively select the signals BX and B 2 when a control signal with a high level is applied, and select the signals A 1 b7w .4 2 when a control signal with a low level Level is present. For example, the second switch 6 switches from the signal A 2 to the signal B 2 in transition from the normal reproducing mode to a special reproducing mode.

During the special playback operation, for example still picture playback from time f 2 to at time f 3, the flip-flop 12 is triggered by the jump time signal that is sent to line 7C via the OR gate 11 is applied.

The flip-flop 12 was cleared by applying the playback operating signal to its clear input and was now triggered by the first jump signal Ca (see FIG. 7C); the Q output then goes from low to high (Fig. 7D). Since the Q output of the flip-flop is used to control the first switch 55, the initial operating state of this first switch 55 is determined so that the signal A 1 is selected before the occurrence of the first jump signal Ca and the signal B 1 when the first jump signal Ca occurs is selected.

In this way, the conversion of the PAL phase takes place without errors during the first jump process; this corresponds to that in FIG. 4D.

This is the color disturbance in the reproduction system, for example a color television monitor, which could adjust without using the device according to the invention, eliminated

The output signal of the flip-flop 12 is then inverted each time the jump signal occurs, and the correct PAL phase conversion is thus maintained by the subsequent operation of the first switch 55. In addition, during this time, the sequence from 1 1 to f 3 in the special playback mode, the MMV 14 is triggered by the trailing edge of the Q output signal from the flip-flop 12 and the negative single pulses after line TE are generated as the OR gate 15 is closed during this time, the negative output pulses of the MMV 14 are not allowed through to the AND gate 13. For this reason, the member 13 transmits the output signal of the member 11 directly as a jump signal for the control circuit of the recording device.

The following is an explanation of the operation of this circuit during the transition period from the special reproducing mode to the normal reproducing mode. The Q output signal may even immediately before the time possessing 1 3 two different output level when the last jump signal Cf.

If it is initially assumed that the Q output signal of the flip-flop 12 changes from the high level to the low level, as it is drawn in solid line in line TD , the first switch 55 is operated so that it outputs the signal A 1 after the occurrence of the last jump signal cf dials. Accordingly, if the second switch 6 selects the signal A 2 at the time f 3, the correct PAL phase change state is set to the right

On the other hand, assuming that the Q output of the flip-flop 12 when the last |

Jump signal C / passes from the low level to the high level (shown in dashed lines in line TD ), the |

Output signal at time f 3 changed back to the lower level as a result of the change de? Signal f

level of the playback mode signal that is applied to the clear input of the flip-flop 12, as the sequence of the dashed line in line TD shows Line TE is drawn in dashed lines. This single pulse signal comes via the now open element 15 to element 13, and this generates an additional jump signal directly after time? 3, as shown in dashed lines in line TG i3 another jump process takes place, so that a phase conversion of the PAL signal is achieved. In this way, the correct phase change state of the PAL signal is maintained during the transition period from the special reproducing mode to the normal reproducing mode.

It can be said that the operation of the circuit shown in FIG. 6 is that an additional Jump signal is generated if the number of jump signals during the timing of the specific Playback mode is odd. Therefore, the number of jump signals can also be used instead of the one shown Flip-flop circuit 12 can be detected with a counter circuit, and it can be the same operating state as that by the The circuit of FIG. 6 achieved by the above description is also made possible by a microprocessor will.

In addition, the initial position of the first switch at the time of transition from the normal reproducing mode to the special reproducing mode can also be determined so that the inverted PAL signal is selected in accordance with a signal corresponding to the termination of the previous special reproducing mode
The operation of this embodiment was, for example, based on a still picture display as a special playback

dergabebetrieb explains, it can be seen, however, that this explanation also applies to the various other types of playback of the playback system is applicable.

The second embodiment of the device according to the invention will now be discussed with reference to FIGS. First of all, in FIG. 8 shows a demodulator circuit of a reproduction system according to the PAL color video system. A PAL color video signal is applied to a Y- C separator 21, and this separates the video signal into a Y signal (luminance signal) and a C signal (chrominance signal). The C signal is then fed to a burst phase discriminator 22 and a color carrier signal separator 23. A color burst signal sin (* y _s f ± 135 °) is recorded in the burst phase discriminator 22 and passed on to an auxiliary carrier signal generator 24. A subcarrier signal sin (<y _s f + 90 °) = cos <y _s f generated in the subcarrier signal generator 24 is changed by 90 ° in its phase relative to a signal sin ω <Χ , which is an average phase of the color burst signal sin (a) _s t ± 135 °). The subcarrier signal generator 24 is in the form of a phase-locked circuit PLL, and an output signal of a voltage-controlled oscillator VCO of this circuit is used as the subcarrier signal cos co _s t . The auxiliary carrier signal cos u) _s t is then fed directly to a switch 26 and a phase converter 25 which generates a signal phase-shifted by 90 ° and a signal phase-shifted by 180 °. The phase-shifted by 90 ° signal, ie a signal eo sin _s t is defined as detecting subcarrier signal applied to a first synchronous detector 27 the phase-shifted by 180 ° signal -cos a) t _s is applied to the switch 26th An output signal ± cos a> _s t is applied to the switch 26. An output signal ± cos a) _s t of the switch 26 is applied to a second synchronous detector 28 as a detection subcarrier signal

Signals (B-Y) sin w _s t and ± (R-Y) cos w _s t are generated in the color carrier signal generator 23, and these two signals are applied to the first synchronous detector 27 and the second synchronous detector 28, respectively and 28 are followed by low-pass filters LPF 29 and 30, respectively, which result in demodulated signals (B-Y) and (R-Y) , respectively.

In a synchronous detector 31, which receives the PAL color video signal, a line activation pulse signal is generated and a flip-flop 32 is triggered, the output signal of which controls the switching state of the switch 26

The phase change state of the color burst signal, i.e. H. the regular phase inversion for each subsequent one Line is detected by the burst phase discriminator and a reset signal is passed on to the flip-flop 12, if the phase change state has changed from the correct phase change state.

As already mentioned, the PAL color video signal has the property that the polarity of the (R-Y) -YMm components of the color carrier signal is changed for each successive line.

Therefore, in order to correctly reproduce the color in the receiving device, it is necessary to change the polarity of the subcarrier signal corresponding to the (R-Y) components in accordance with the phase change of the color burst signal. For this reason, the burst phase discriminator 32 is used to reset the flip-flop 32 when (as described above) the synchronous detector 28 generates a signal - (RY).

However, if the response speed of the burst phase discriminator is too fast, the problem arises that the reset pulse signal also, as already mentioned, in dependence on contained in the color video signal Noise components is generated. To avoid this, a time-holding characteristic is used for the Burst phase discriminator provided. However, this time-keeping characteristic creates a problem in turn when a video disc player VDP is used as the source for the PAL color video signal, especially in search mode is used. During the search operation, the detection device is in the radial direction of the plate shifted to find a desired recording track, while a track servo loop controls the location of the Controlled detection point of the detection device with the aid of a control signal that is derived from the playback information signal is produced. In order to keep the track during the search operation, a device for moving the scanning or tracking position of the detection device in the radial direction of the plate, for example a tracking mirror is operated in a manner which will be described later. When playing the recorded information also takes place during the search operation, the track mirror rotates around its Axis that a read out light beam in spite of the radial movement of the detection device on a recording track is focused. When the track mirror is rotated to an extreme point of its range of motion there is an immediate rotation of the mirror to the other extreme point of its range of motion, so as to start reading out the information from a new starting point of the recording track. With In other words, a so-called jumping process takes place every time this rapid movement of the track mirror. Since the portions of the recording tracks on which the line sync signals are recorded ' are aligned in the radial direction of the disk, the operation of the servo system for disk rotation correctly maintained during the search operation. As a result of the phase rigidity of the VCO provided therein the PLL circuit of the subcarrier signal generator 24 can easily be set within one field (a horizontal Line) can be locked with the input signal after each jump process during the search mode.

However, the problem involved in the search operation is that the phase change state of the color burst signal can be reversed after a jump, since the number of skipped tracks is a jump process is not constant (see FIG. 9). If the phase change state after a jump operation according to FIG. 9 incorrect, d. H. is rotated exactly by 180 °, there will be a disruption of the color rendering or the Commissioning of a color kill circuit generated

Now, based on Fi g. 10, the second embodiment of the color signal processing apparatus explained a PAL-color video signal is generated by a detection operation as reproduction RF signal from a recording disk and directly to a low-pass filter LPF 33 and a band-pass filter BPF 34 is supplied to the LPF 33 and the BPF, the video signal each into a luminance signal and a color carrier signal (including the color burst signal) having a frequency of 4.43 MHz separated the carrier chrominance signal from the BPF 34 is then a PAL phase converter 35 supplied by the heterodyne type of converter, the PAL-phase converter 35 includes a multiplier circuit 351 and a bandpass filter BPF 352. In the multiplier circuit 351 , the color subcarrier

signal multiplied by a signal cos 2cu _s t coming from a frequency multiplier 36. The BPF 352 |

serves to extract a fundamental frequency _{component (δ> s} ) from the output signal of the multiplier circuit 351

!,. ehmen. The output signal of the BPF 352 is applied to a switch 37 as an input signal, and the switch |

37 also receives a signal directly from the BPF 34. $

The output signal of the BPF 34 is also fed to a burst gate 38, in which a color burst signal is received. The color burst signal from burst gate 38 is then fed to a phase converter 39 and an auxiliary carrier signal generator 40. The auxiliary carrier signal generator 40 is the same as the auxiliary carrier signal generator 24 in FIG. 8 constructed with a PLL circuit In the phase converter 39, the color burst signal from the burst gate 38 is converted in accordance with its phase converter control signal from line a, which has a period of 2 / i, where f / is the period of a line pass 41 in which the signal from the phase converter 39 is multiplied by the signal cos eo _s t from the subcarrier signal generator 40. The thus demodulated signal from the burst demodulator 41 is fed to a zero level comparator 42. The switch 37 is controlled by the output signal of the zero level comparator 42 and the output signal of the switch is added to the luminance signal in the adding circuit 43 so that a reproduced PAL color signal is created. The playback PAL color signal is then, for example, the one shown in FIG. 8 of the playback system circuit shown

The operation of the circuit according to FIG. 10 is described below with reference to FIG. 11 and 12 explained further. Lines UA to HEin, FIGS. 11 and 12A to 12B in FIG. 12 are each time-dependent processes of the signals which occur at the locations in FIG. 10 marked with small letters. The signals in FIG. 11 the correct state of the phase change of the color burst signal. In the phase converter 39, a component of the color burst with the phase position - 135 °, which is present in every second line (2H) , is converted to a signal with the phase + 45 ° (dashed line in FIG. 1) Phase converter 39 the form of signals sin (m _s t + 135 °) and sin (eo _s t + 45 °), which occur alternately in each pass \ H (line WC). In the burst modulator 41 there is a multiplication of the output signal sin (<ö _s r + 135 °), sin (co _s t -} - 45 ^o ) with the output signal cos w _s t of the subcarrier signal generator 40. The output signal of the burst demodulator 41 can now can be expressed mathematically as follows:

sin (fi> _s f + 135 °) · cos <w _s f = V ₂ [Sm (2co _s t + 135 °) + sin 135 °], (3)

sin (fi) _s t + 45 °) · cos co _s t = V ₂ [SIn (2a> _s t + 45 °) + sin 45 °]. (4)

Since only the components with a low frequency are allowed to pass, the output of the

Burst demodulator 41 in a DC voltage signal of positive polarity, as line HD shows If this If a positive DC voltage signal is present, the zero level comparator 42 generates a control signal with a high level, which controls the switch 37 so that the output signal of the BPF 34 is selected. In this case, therefore the PAL color video signal is applied directly to the display device without passing it through the

Color carrier phase change process.
If the phase change state of the color burst signal according to FIG. 12, as line 12ß shows, the reverse of that

In the case just described, the circuit works in the following way: the output signal of the phase converter 39 takes the form of signals sin (<o _s f −135 °) and sin (o) _s t −45 °), which alternately be ^: 'i -. * ¹ " η pass IH occur according to line 12C. The output signal of the burst demodulator 41 can now be expressed in the following way:

sin (<y _s t -135 °) ■ cos e> _s t = V ₂ [SIn (2 ^ -135 ° + sin (-135 °)], (5)

sin [a> st + 45 °) · cos w _s t = V ₂ [Sm (2a) _s t -45 °) + sin (-45 °)]. (6)

Therefore, the output signal of the burst demodulator 41 is a DC voltage with negative polarity. Because of this negative DC voltage, the zero level comparator 42 generates a lower level output signal for driving the switch 37 so that it selects the output signal of the PAL phase converter 35. The operation of the PAL phase converter 35 will now be specifically described. If the color carrier signal including the color burst signal is expressed as sin (iy _s f + Φ) , the output of the multiplier circuit 351 takes the form:

cos a) _s t ■ sin (<y _s i + Φ) = V ₂ [sin (3ß> _s f + Φ) + sin (o) _s t - £>)]. (7)

After passing through the BPF 352, only the fundamental frequency component sin (w _s t - Φ) is applied to the switch 37. As with the B- Y component of the color carrier signal, the phase of the output signal sin o) _s t of the BPF 352 is the same as that of the input signal to the phase converter, since the value Φ is equal to zero (Φ = 0).

Conversely, for the R - Y component of the subcarrier signal, the phase of the output signal sin (co _s t - πΙ2) of the BPF 352 is reversed to the phase of the phase converter input signal sin (co _s t + λγ / 2), since its # value is equal to "t / 2 is (Φ = ir / 2). In the same way, in the case of the color burst signal, the phase of the output signal sin (co _s t + 135 °) is reversed to the phase of the input signal sin (ft> ₅ ± 135 °). In this way, the PAL phase conversion is carried out. The outputs of the switch 37 in both cases are like a comparison of the lines HE and 12E

b ^r i shows identical.

In addition 7 sheets of drawings

Claims (4)

Patent claims: 1. Color television signal processing apparatus for use with a display unit for after PAL television system recorded video information with normal playback operation and a special one Playback mode, with a color carrier signal phase compensator connected to the display unit with a separator device for transmitting the chrominance component of the scanned color video signal, with a phase converter connected to the separator for inverting the PAL switching phase of the chrominance component, with a first switch for selecting either the output signal of the Separator device or the output signal of the phase converter and with an adding device for the output signal of the first switch and the luminance component of the output signal of the playback unit,
a second switch for selecting either the output signal of the reproducing unit during the normal reproducing operation or the output signal of the adding device during the special reproducing operation, and with a control device for controlling the switching state of the first switch such that the continuity the PAL switching phase during the transition from normal operation to special operation and vice versa is maintained, wherein the control device during the special playback mode, the first switch in Dependence on jump command signals between the output signal of the phase converter and that of the Separator device switches back and forth, characterized in that that the control device switches the second switch (6) to the output of the adding device (56) immediately upon occurrence of a special playback type signal and at the same time applies the first switch (55) to the output signal (A 1) of the separator device (51) and that the first switch ( 55) is switched over when the next jump command signal occurs. 2. Processing device according to claim 1, characterized in that a device (14, 15, 13) for Generation of an additional recording track jump command signal is provided, if the number of Recording track jump command signals during the special playback mode is odd 3. Processing device according to claim 1, characterized by a to the separator device (34) connected device (39,40,41,42) for detecting a change in a PAL phase change state of the color burst signal before and after a certain point in time and for generating a control signal according to the result of the acquisition process. 4. Processing device according to claim 3, characterized in that the device for detecting the phase change comprises the following components: a color burst signal phase converter (39) for phase conversion of the color burst signal (b) at each horizontal line sequence, a subcarrier signal generator (40) for generating a subcarrier signal from the color burst signal (b), a MultipHkatoreinrichtung (41) for multiplying the output signal (c) of the color burst signal phase converter (39) with a signal whose frequency and phase equal to the frequency and phase of the Subcarrier signal is to create a phase change state of the color burst signal indicative of DC voltage component (d) and a control signal generator (42) for generating the control signal corresponding to that by the multiplier means (41) obtained direct voltage component.