JPS6098789A - Cross talk detection device - Google Patents

Abstract

PURPOSE:To allow detection of cross talk also for a CAV disk by detecting an amplitude fluctuation component of color burst of a reproducing video signal and by detecting cross talk from an adjacent record truck. CONSTITUTION:A reproducing color video signal A is impressed onto a BPF1, and extracts a color burst signal B containing a chroma component. The signal B is supplied to an AM detector 2 and rectified. A rectifier output C is impressed on a sample hold S/H circuit 4 after high frequency components such as color sub-carrier frequency of the rectifier output C are removed. A hold output E is impressed on an LPF6 and its high component is removed. An output F of the LPF6 becomes input of an AM detector 7 and is rectified. A rectifier signal G is impressed on an LPF8, turning into a direct current component H, and becomes cross talk detection output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crosstalk detection device, and more particularly to a crosstalk detection device in a recorded information reproducing device such as a video disc player or a VTR.

In a recorded information reproducing apparatus, when a cross phenomenon occurs, which is adversely affected by information on a track adjacent to a read recording track during dragging, it becomes difficult to reproduce good information. In an optical information reproducing device, the recording track is distorted due to aberrations of the pickup lens and the introduction of convergence Distortion occurs in the spot shape of the beam converged upward (this is why cyclotalk occurs).

The causes of the tilt angle between the beam optical axis and the disk include, for example, the disk becoming umbrella-shaped due to aging, and the disk rotation axis becoming tilted due to changes in the shape of the disk rotation axis fixing system of the playback device. etc., and the occurrence of crosstalk is unavoidable due to problems after the product is shipped.

Therefore, as an example of a device that automatically detects the amount of crosstalk and prevents it, there is one disclosed in Japanese Patent Application Laid-open No. 186233/1983.

To explain the principle of this device using Fig. 1, for example (
8,5M l-I which is a constant frequency as shown in A)
For example, 7°5 M l from an adjacent track is recorded in the recording section in which the information that determines the FM carrier A7 frequency of Z is recorded.
-If information on the FM carrier frequency of IZ is leaked as crosstalk, there will be a difference in image frequency in the reproduced signal obtained by FM detection of this.
The Be1 component of l-IZ is included as one stalk and output. Considering this in the case of video information, the information that has a constant FM frequency of 8.5 Mt-lz is shown in (B), which corresponds to the gray level J, and the FM frequency of 7.5 Mt-lz. The adjacent track component whose frequency shifts to the right corresponds to the sync tip level. Therefore, the Go-1 component of C11'Ml-Iz appears as a particularly noticeable 1stoke at the position C where the gray level image 4gH is lined up with the horizontal synchronizing signal of the adjacent rack.

However, when the recording disk is a CLV (constant linear velocity) type 6 type, 1 MH2 crosstalk is particularly noticeable when the synchronization signal part of the adjacent L/rack appears on the gray screen as U talk. . Therefore, if a beat is detected in the reproduced video signal under such conditions, crosstalk can be detected. , especially during the number 1-1 (horizontal period) of the multiplied retrace period of the video signal, it has only gray level information. By selectively extracting the signal using a gate circuit or the like, crosstalk can be detected (EJ function).

The crosstalk detection device disclosed in the above-mentioned publication MJ is based on this principle. However, this device has a stone f/J) for CLV recording disks, but for CAV (constant angular velocity) disks;
C has the disadvantage that it cannot be applied. CAV disk C is
Modulation of the above constant frequency between adjacent 1-racks (the sections where No. 1□ are recorded are aligned with the same radius, so the crosstalk component can be calculated from the read information by 111 m-
This is because it is impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cross-streak detection device that can very easily detect cross-streaks in not only CLVlj type discs but also CAV type discs.

A crosstalk detection device according to the present invention is characterized in that an amplitude fluctuation component of a color burst of a 111 cow video signal is detected, and crosstalk from adjacent recorded tosic can be detected using this amplitude fluctuation component.

The present invention will be explained below using the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, in which the reproduced color video signal A (A) is an F3PF (band pass filter).
1/\ is applied, and a color burst signal (B) containing a chroma component is separated and extracted. This extracted signal ([3) is supplied to the ΔM detector 2 and rectified. This rectified output (
C) is applied to an LPF (low bass noise filter) 3, where high frequency components such as the same wave number as the color rib 11 are removed and applied to the next stage s/1 (ripple hold) circuit 41. This S/H circuit 4 sample pulse (D>
1 non-pull pulse generator based on playback 1' sink 55
It is something that can be taken away completely.

This small field output (2) is applied to LPF 6 and high frequency components are removed. This L P F 6 Deno J (
F) 1.1 AM It becomes the manual power of the M detector 7 and is rectified. This rectified signal (G) is applied to t-1) F8 and converted into a core number component (+-1) to serve as a crosstalk detection force.

The operation of the present invention will be explained below using an optical bidet A disc brake A as an example.

Since this player employs the so-called Guillef 1-M modulation system, the formula for the FM modulation signal in the color burst portion is as follows.

B (t) = cos (ωct−+−m sinωm
t) Here, ωC is the carrier angular frequency, n+ +; L☆
ωm is the angular frequency of the color burst. Here C
, 130(1) from the adjacent track by one cross
When a signal component of 1 to 2 is mixed into the CAM disk, the adjacent 1 to 1 racks of the CAM disk are also recorded portions of color bursts, so the relevant crosstalk component is calculated by the following equation.

Bc (t) = kcos(ω ct + ψ C−
111Sin (ω lnt+ψl1l)) Here, 1( is a coefficient that takes into account the magnitude of contamination, and ψC is the read signal B(t) and the crosstalk signal;) 13C(()
The carrier phase difference with ωm is [3(t) BC(t)
This is the color burst phase difference.

Therefore, the reproduced signal Bp(t) is calculated using the above formula % [3p(shi)-・[3(t)+BcN] Amplitude fluctuation of the reproduced color burst signal after frequency detection of this Bp(t) The component Pam is a function of the above 1(, ψC1ψm. This φC1ψm is determined at the time of cudding the disk, but it is generally difficult to reach zero due to the rotation accuracy of the disk force cutting machine, and at the same time ψ
It is inevitable that the value of c1ψm fluctuates.

Furthermore, during disc playback, the value of ψC1ψm varies by J, -C at the playback location on the disc, which is due to the rotation angle Ij+
Unavoidably, these fluctuations result in a reproduced color burst C. Further, as the value of k changes, the amplitude fluctuation component amount pam of the reproduced color burst changes. If 1 becomes larger, Parrl becomes smaller, and if k becomes smaller, l]am'0 becomes smaller. If the value becomes 1, then Pam()t20.

Based on this principle, the embodiment shown in FIG. 2 is an example of detecting the L1 strike using the amplitude variation O component of the reproduced can burst. Figure 3 shows the operating waveforms of the device in Figure 2, and (△) to (+-1) correspond to the waveforms of the openings (A) and (1-1>) of each part in Figure 2, respectively. The level of faith z <i+> will indicate the hanging of Talostalk.

Note that the above example is for the j speed of the CΔV disc (however, in the case of the CLV disc, the signal BC(t) indicates the reproduction image (ii) and However, it is true that the amplitude fluctuation component of the reproduced color burst indicates the magnitude of the crosstalk.

For example, if the relative inclination angle with respect to the pick-up beam is adjusted so that the level of the detection 'i3 (1-1) thus obtained is minimized, the crosstalk interference appearing on the playback screen will be minimized.

As described above, according to the present invention, C
Closts can be detected not only on LV de C discs but also on CΔV discs, and their effects will be hot.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the operating principle of a conventional crosstalk detection device, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 3 is a waveform diagram showing the operation of the blocks in Fig. 2. . Explanation of symbols for the 1-day type part 1...BPF 2.7...ΔM detector 3.8...LPF 4...S/l-1 Circuit applicant Pioneer Co., Ltd. agent Patent attorney Motohiko Fujimura (external 1st Lu)

Claims (1)

[Claims] Crosstalk detection in a recorded information reproducing apparatus characterized by detecting an amplitude fluctuation component of a reproduced video signal (colorverse) and detecting an amount of crosstalk from adjacent recordings 1 to 3 based on this amplitude fluctuation component. Device.