JPS6331998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a reproducing device for a recording disk or the like on which video signal information is recorded, and is capable of displaying the video signal information detected from the recording disk or the like on the screen of a normal television receiver. The present invention relates to a video signal processing device that converts into a video signal.

For example, in a rotating disk-shaped recording medium on which video signal information is recorded, that is, a recording disk (hereinafter referred to as a video disk), the video signal and audio signal are generally frequency-modulated and recorded.

Here, using an example of a video disc and its playback device, and referring to FIGS. 1 and 2, a schematic configuration of a portion of the playback device that detects video signal information from a video disc and detection of video signal information will be described. Give a basic explanation of what to do.

In FIG. 1A, reference numeral 11 denotes a video disk on which, for example, a spiral recording line is set concentrically on the rotating surface, and on which FM-modulated video signal information, for example, is recorded. This video disc 11 is
It can be placed coaxially on a turntable 12 and is rotationally driven by this turntable 12. On the upper surface side of the video disk 11, there is an arm device 1 that is movable in parallel in the radial direction of the disk.
3 is provided, and this arm device 13 is controlled to move toward the center of the disk or toward the outer circumference by a carriage device 14. The arm device 13 has an opening 131 in the lower abdominal wall of its rectangular cylindrical body, so that the regeneration needle 15 can be lowered or raised. This is because the needle arm 16, which supports the regenerated needle 15 at one end, is driven by the repulsion or attraction force of the electromagnetic field.

FIG. 1B shows a cross-sectional structure of the video disc 11. FIG. In the figure, 111 is a disk substrate made of synthetic resin. Pit 112 is formed along the recording line on this disk substrate 111, a metal plating film 113 is applied on the upper surface, and a dielectric material 114 is further applied on the upper surface of this metal plating film 113. The upper surface of this dielectric 114 is coated with a slippery material 115. The video signal information is recorded as changes in the length and spacing of the pits in the line direction. In the reproducing needle 15 that comes into sliding contact with such a recording line, a metal plating film 152 is provided as an electrode on a needle body 151 made of sapphire.
As a result, a capacitance is generated between the electrode of the playback needle 15 and the electrode of the video disk 11, and a change in this capacitance is detected by a circuit as shown in FIG. 2a. That is, the capacitor 171 between the reproducing needle 15 and the disk 11 is a component of the resonant circuit 17, and the oscillation output of the UHF oscillator 18 is inductively coupled to the resonant circuit 17. When the capacitance 171 changes, the characteristics of the resonant circuit 17 change within the range shown by the broken line and solid line in FIG. 2b. and,
The oscillation frequency F ₁ of the UHF oscillator 18 is set at the slope part of the resonance frequency characteristic. Therefore, if there is a change in the capacitance 171, the diagram A in FIG.
At the point, an output as shown in FIG. 2C is derived due to the shift of the resonance characteristic. This is diode 1
9. By a detection circuit such as a capacitor 20, the second
The signal is rectified and output as shown in Figure d. This corresponds to the FM waves recorded on the disk.

Next, an example of a tracking means for the regenerated needle 15 will be explained using FIG. For example, pits 11 for video signal information are placed along recording lines set in a spiral shape.
Tracking control signals f 1 and f 2 of the playback needle are placed on both sides of the video signal information track T in which the signals f ₁ and f ₂ are arranged.
pits 211 and 212 are arranged. The tracking position deviation of the regeneration needle is corrected by, for example, comparing the amplitudes of the control signals f ₁ and f ₂ detected by the regeneration needle, and depending on this comparison error signal, for example, the arm device 13 (see FIG. By energizing a tracking coil (not shown) provided in the recording medium (see a), the playback needle is driven in the radial direction of the video disc by the force of the electromagnetic field.

By the way, a video signal includes a luminance signal and a color signal, and then is frequency modulated (FM) and recorded. In this case, the color signal is superimposed on the low range of the luminance signal in a state in which the phase is inverted every horizontal scanning period, ie, in a so-called frequency interleaving state. The above FM standards are shown in Figure 4. That is, the white peak of the video signal V is 6.3MHz, and the leading edge of the synchronization signal is 4.3MHz. Considering the upper and lower waves, the bandwidth is approximately 1.3MHz to 9.3M.
Hz. Note that the carrier color signal frequency is converted to 1.53MHz (interleaved frequency).

And the audio signal will not affect the video signal.
Frequency modulates and records carrier waves of 1.3MHz or less.
In this case, for example, there is a method of duty cycle modulating a video FM carrier wave with an audio FM carrier wave and recording the audio signal on the video signal pit.

FIG. 5 shows a conventional example of a video signal processing apparatus that detects the above-mentioned video signal information from a video disc with a playback needle and converts it into a signal that can be displayed on the screen of an ordinary television receiver. In the figure, video signal information picked up by a playback needle 32 from a video disk 31 is detected by a signal detection circuit 33 as shown in FIG. 2A, for example, and is supplied to an amplifier circuit 34. The output of this amplifier circuit 34 is supplied to an FM detection circuit 36 via a limiter circuit 35 and subjected to FM detection. This detected output is supplied to a modulation circuit 39 via a low-pass filter 37 and a dropout compensation switch circuit 38. The carrier color signal frequency of the detection output is
Since it is converted to 1.53MHz, this modulation circuit 3
9, it is modulated by the 5.11MHz oscillation output of the oscillation circuit 40, and the output terminal of the modulation circuit 39 is
A carrier color signal frequency of 3.58MHz is obtained. The output of the modulation circuit 39 is supplied to a 1H delay device 41 that delays the signal by one horizontal scan (1H), and is also supplied to one input terminal of a subtraction circuit 42. The output of the 1H delay device 41 is sent to a subtraction circuit 42.
The signal is supplied to the other input terminal of the detector circuit 43 as well as to the detection circuit 43 . This detection circuit 43 converts the output video signal of the modulation circuit 39 into the modulation circuit 3.
9, it is converted into a video signal before being modulated. The output of this detection circuit 43 is supplied to the selected terminal of the dropout compensation switch circuit 38 via a low-pass filter 44 and an amplifier circuit 45.
It is supplied to one input terminal of the adder circuit 46.
The output of the dropout compensation switch circuit 38 is supplied to the other input terminal of the adder circuit 46 via a phase shift circuit 47.

The 1H delay device 41, the addition circuit 46, and the subtraction circuit 42 have comb filter characteristics that utilize the relationship of frequency interleaving. That is, the video signal delayed by one horizontal scan and the undelayed video signal are processed by the subtraction circuit 4 as described above.
2, the color signal component is derived at the output terminal of this subtraction circuit 42. When supplied to the adder circuit 46, a luminance signal component is derived at the output end of the adder circuit 46.

The color signal component is then supplied to one input end of an adder circuit 50 via a band pass filter (3.58MHz) 48. Further, the luminance signal component derived to the output terminal of the adder circuit 46 is transmitted to the adder circuit 46 via a delay line 49 for time alignment with the color signal component.
0 to the other input terminal. A signal that can be displayed on the screen of an ordinary television receiver is derived from the output terminal of the adder circuit 50.

However, in the video signal processing device having the above configuration, the chrominance signal and the luminance signal can be separated only after a perfect frequency interleaving relationship is established in the circuit portion having the comb filter characteristic. However, if a perfect frequency interleaving relationship does not hold, the chrominance signal in the luminance signal cannot be effectively canceled, resulting in dot interference. Further, the color signal is reproduced by one horizontal scan.

This invention has been made to address the above-mentioned circumstances, and includes dot interference that occurs when separating luminance signal components and color signal components using a comb filter.
It is an object of the present invention to provide a video signal processing device that can correct residual color signal components that appear more than one horizontal interval.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 6 and 7. First, in FIG. 6, video signal information is picked up by a playback needle 62 from a video disk 61 rotating at a predetermined number of rotations, is detected by a signal detection circuit 63, and then passed through an amplifier circuit 64 and a limiter circuit 65 to FM detection. circuit 6
6. The video signal FM-detected by this FM detection circuit 66 is passed through a low-pass filter 67 and a dropout compensation switch circuit 68 to a modulation circuit 6.
9. The video signal supplied to the modulation circuit 69 is modulated by the 5.11 MHz oscillation output from the oscillation circuit 70, thereby converting the carrier color signal frequency from 1.53 MHz to the 3.53 MHz band. The output of the modulation circuit 69 is supplied to a 1H delay device 71 which delays it by one horizontal scanning period, and is also supplied to one input terminal of a subtraction circuit 72. Also
The output of the 1H delay device 71 is supplied to the other input terminal of the subtraction circuit 72. If the signal supplied to the 1H delay device 71 has a frequency interleaving relationship, the subtraction circuit 7
A color signal component is derived from the output terminal of No. 2. This color signal component is supplied to one input terminal of an adder circuit 75 via a bandpass filter 73 and a trap circuit 74.

The output of the 1H delay device 71 is further supplied to a detection circuit 76. This detection circuit 76 returns the input signal to the signal before being input to the modulation circuit 69. The output of this detection circuit 76 is supplied to an amplifier circuit 78 via a low-pass filter 77. This amplifier circuit 78 adjusts the level of the input signal to the same level as the signal level before being input to the modulation circuit 69. This amplifier circuit 7
8 is supplied to the selected terminal of the dropout compensation switch circuit 68 and also to one input terminal 791 of the adder circuit 79. The other input terminal 792 of this adder circuit 79 is supplied with the signal before being input to the modulation circuit 69 via a phase shift circuit 80 . The phase shift circuit 80 performs phase compensation between signals subjected to addition processing in the addition circuit 79. That is, an undelayed signal is derived from the output of the dropout compensation switch circuit 68, but
The delayed signal is passed through a detector 76 and a low-pass filter 7.
7. Since the color signals are applied to the adder circuit 79 through the amplifier 78, the phase is controlled so that the phase difference between the color signals supplied to each input terminal 791, 792 is 180°C.

In the adder circuit 79, both input terminals 79
If a frequency interleaving relationship is established between the signals supplied to the adder circuit 7
The luminance signal component from which the color signal component has been removed is derived from the output terminal of 9. This derived luminance signal component is passed through a time adjustment delay line 81 to a subtraction circuit 82.
is supplied to one input terminal of The delay line 81
is for correcting the time axis of the added luminance signal component and the color signal component separated by the subtraction circuit 72. The output of the subtraction circuit 82 is supplied to the addition circuit 75 via the addition circuit 83. The luminance signal component supplied to the adder circuit 75 is combined with the color signal component supplied from the subtracter circuit 72 side, and the output terminal of the adder circuit 75 receives a video signal that can be reproduced by a normal television receiver. can get.

By the way, considering the part that is not related to frequency interleaving, the output of the adder circuit 79 will continue to increase the color signal for one horizontal scanning period even after the color signal component C disappears, as shown in FIG. 7b, which will be described in detail later. Component C comes out. Furthermore, the luminance signal component B is affected by the amplitude of the luminance signal component B one horizontal scanning period ago.

Here, the processing configuration of the color signal component and the luminance signal component in the portions not related to frequency interleaving will be explained.

A signal supplied to one input terminal 791 of the addition circuit 79 is supplied to one input terminal 8 of the subtraction circuit 84.
41 is also supplied. Further, the signal supplied to the other input terminal 792 of the adder circuit 79 is supplied to the subtracter circuit 84.
is supplied to the other input terminal 842 of. The output of the subtraction circuit 84 is supplied to the addition circuit 83 and first and second level comparison circuits 86 and 87 via a low-pass filter 85. The first level comparison circuit 86 derives a logic "1" when, for example, the output of the low-pass filter 85 is in the negative direction compared to the reference level. The second level comparison circuit 87 derives logic "1" when the output of the low-pass filter 85 is in the positive direction compared to the reference level. The outputs of the first and second level comparison circuits 86 and 87 are outputted to an OR circuit 88.
is supplied to. This OR circuit 88 is further supplied with the output of a pulse amplification circuit 91. The output of the OR circuit 88 is connected to the control terminal of the switch circuit 92. This switch circuit 92
The output of the band pass filter 89 in the color signal band is applied to the subtraction circuit 82 using the output of the OR circuit 88 as a control signal. That is, the output of the delay line 81 is added to the bandpass filter 89 . And this band pass filter 89
The output of is supplied to the switch circuit 92 and also to the saturation line detection circuit 90. The output of the saturation line detection circuit 90 is supplied to the OR circuit 88 as described above, and is further supplied to the control terminal of the trap circuit 74.

The operation in the above configuration will be explained. That is,
Assume that the video signal at the output end of the dropout compensation switch circuit 68 is as shown in FIG. 7a. In FIG. 7, H ₁ , H ₂ , H ₃ . . . each indicates one horizontal scanning period. here,
Suppose that a signal from the horizontal scanning period (H ₁ ) is applied to the input terminal 792 of the adder circuit 79, and a signal from one horizontal scanning period ago, which is substantially similar to this signal and has a frequency interleaving relationship, is applied to the input terminal 791. , the output of the adder circuit 79 becomes a signal corresponding to the period (H ₁ ) in FIG. 7b, and is derived as the luminance signal component B. Further, in the adder circuit 84, a color signal component C is derived, but this is passed through a low-pass filter 85, so that it appears as a constant DC reference level as shown in FIG. 7c. Therefore, only the luminance signal component B is obtained from the adder circuit 83, as shown in FIG. 7h.

In addition, in the subtraction circuit 72, the luminance signal component B is canceled as shown in FIG. Added.

Next, the horizontal scanning period (H ₂ ) shown in FIG. 7 will be explained. That is, this period (H ₂ ) is a case where there is no vertical correlation with respect to the previous period (H ₁ ).

In the adder circuit 79, the signal of this period (H ₂ ) (undelayed signal) and the signal of the period (H ₁ ) one horizontal scanning period before this (delayed signal)
are added, resulting in a signal shown in period (H ₂ ) in FIG. 7b. Partial color signal component C remains without being canceled. This signal is then supplied to a subtraction circuit 82 via a delay line 81. On the other hand, at this time, in the subtraction circuit 84,
Since the signal of the period (H ₂ ) and the signal of the period (H ₁ ) are subtracted and passed through the low-pass filter 85, a signal as shown in the period (H ₂ ) of FIG. 3c is obtained.
This signal is then added to the adder circuit 83,
As shown in the period (H ₂ ) of FIG. 7h, the DC component of the luminance signal component B can be compensated for.

Furthermore, the output of the delay line 81 is also applied to a bandpass filter 89. Therefore,
This filter 89 can extract the color signal component C mixed in the period (H ₂ ) as shown in the period (H ₂ ) in FIG. 7d. The output of this bandpass filter 89 is applied to a switch circuit 92 and also supplied to a saturation line detection circuit 90. Therefore, the pulse amplifier 91 generates a pulse for a period including the color signal component C, as shown in period (H ₂ ) in FIG. 7e. Further, in the first and second level comparison circuits 86 and 87, pulses as shown in FIG. 7f and g are generated. Therefore, Figure 7 e, f, g
Since each pulse passes through the OR circuit 88 and opens the gate of the switch circuit 92, the color signal component C is added to the subtraction circuit 82 during the period in which the color signal component C is mixed. As a result, the subtraction circuit 82
From this, a luminance signal component B from which the color signal component C is completely removed is obtained.

The luminance signal component B at this time still requires correction to the DC level, but this is corrected because the output of the low-pass filter 85 is added in the adder circuit 83 as described above.

On the other hand, the output of the bandpass filter 73 is the seventh
As shown in period (H ₂ ) in Figure i, the color signal is reproduced one horizontal scanning period longer than the original color signal. Therefore, the 3.58 MHz band trap circuit 74 is turned on by the output of the pulse amplifying circuit 91, and the color signal component derived for one horizontal scanning period is erased as shown in 7j. The color signal component from the trap circuit 74 and the luminance signal component from the adder circuit 83 are transferred to the adder circuit 7.
5 and converted into a video signal that can be displayed on the screen of an ordinary television receiver.

As described above, according to the present invention, it is possible to correct the dot interference that occurs when the luminance signal component and the color signal component are separated using a comb filter, and the remaining color signal component that appears more than one horizontal interval, which is an excellent result. A video signal processing device that can contribute to obtaining a reproduced image can be provided.

[Brief explanation of the drawing]

FIG. 1a is a schematic perspective view for explaining the principle of a recording disk reproducing device, and FIG. 1b is an enlarged cross-sectional view of the main part of the recording disk, showing an example of a signal recording method of the recording disk.
Figures 2 a to d are circuit diagrams of a circuit that detects signal information from a recording disk, as well as characteristic diagrams and signal waveform diagrams to explain the operation of each part of this circuit. Figure 3 shows a tracking control signal for a reproduction needle. 4 is an explanatory diagram of the standard of the signal recorded on the recording disk, FIG. 5 is a block diagram showing a conventional example of a video signal processing device, and FIG. 6 is a video signal according to the present invention. A block configuration diagram showing an example of a processing device,
FIGS. 7a to 7j are signal waveform diagrams for explaining the operation of FIG. 6. 72, 82, 84...subtraction circuit, 73, 89...
... Bandpass filter, 74 ... Trap circuit, 7
5, 79, 83... Addition circuit, 85... Low-pass filter, 86, 87... Level comparison circuit, 88...
OR circuit, 90... Saturation line detection circuit, 91... Pulse amplification circuit, 92... Switch circuit.

Claims (1)

[Claims] 1. A first adding circuit that adds a horizontal period delayed video signal and an undelayed video signal to first and second input terminals, respectively, and performs an addition process on these signals; and the first and second input terminals. A first subtraction circuit that performs subtraction processing of the signal, and the output of the first addition circuit are added via a second subtraction circuit, and the output of the first subtraction circuit is added via a low-pass filter. The output of the low-pass filter is added to the second adder circuit, and the output of the low-pass filter is compared with a predetermined reference level. a level comparison circuit that derives a logical output when the signal becomes low, a band filter to which the output of the first adder circuit is added and set to the color signal frequency band, and an output of this band filter to which the output is selected. a switch circuit added to the second subtraction circuit, a saturation line detection circuit to which the output of the bandpass filter is also added, a pulse amplification circuit to which the output of this detection circuit is added, and this pulse amplification circuit and the level comparison circuit. an OR circuit for logically ORing the outputs of the circuits and controlling the switch circuit; means for performing a subtraction process between the delayed video signal and the non-delayed video signal to separate color signals; and means for separating the color signals. a trap circuit to which the output of the trap circuit is applied and which is turned on by the output of the pulse amplification circuit and has an attenuation characteristic in the color signal band, and the addition of the output of this trap circuit and the output of the second addition circuit. A video signal processing device comprising a third addition circuit that performs processing.