JPH02216675A - Reproducing device for recording information including address signal - Google Patents

Abstract

PURPOSE:To prevent erroneous information retrieval by stopping the compensating operation of drop-out at least for the period of the occurrence of drop-out at the time of the occurrence of drop-out in an address signal section. CONSTITUTION:A drop-out detecting means 7 to generate a drop-out detection signal and a detecting means 14 to generate an address section detection signal are provided. A gate means 8 is provided which stops passage of the drop-out detection signal only at the time of existence of the address section detection signal, and the compensating operation of a drop-out compensating circuit is controlled based on the output of the gate means 8. Consequently, when drop-out occurs in the address signal section, drop-out compensating operation is stopped at least for the period of this occurrence. Thus, erroneous information retrieval is prevented.

Description

TECHNICAL FIELD The present invention relates to a recorded information reproducing apparatus, and more particularly to a recorded information reproducing apparatus including an address signal for information retrieval.

BACKGROUND ART In addition to video and audio information, a recording medium such as a video disk includes an address signal to facilitate retrieval of this information.

On the other hand, the dropout phenomenon in the reproduced signal is unavoidable, and therefore a dropout compensation circuit is often added to compensate for the reproduced signal.

In cases where such a dropout compensation function is provided,
If a dropout occurs during a period corresponding to the address signal in the reproduced signal, dropout compensation will naturally be performed and the signal will be replaced with, for example, a signal from before IH (one line) during that period. As a result, not only a normal signal is not derived as the address signal, but also a completely different compensation signal is derived, which is undesirable because it causes erroneous information retrieval and significantly reduces its reliability.

Summary of the Invention [Object of the Invention] Therefore, an object of the present invention is to provide a recorded information reproducing device that prevents address information from being replaced with incorrect address information when dropout occurs in an address signal section. shall be.

[Structure of the Invention] A recorded information reproducing apparatus according to the present invention includes a dropout compensation circuit that detects dropouts in a reproduced signal of recorded information including an address signal for information retrieval and performs dropout compensation. dropout detection means for detecting the dropout and generating a dropout detection signal over at least a dropout occurrence period; and a dropout detection means recorded at a predetermined position with respect to a synchronization signal included in the recorded information detection means for detecting a period in which an address signal is included and generating an address section detection signal over the detection period; and gate means for blocking passage of the dropout detection signal only when the address section detection signal is present. and is configured to control the compensation operation of the dropout compensation circuit based on the output of the gate means.

[Operation of the Invention] In the recorded information reproducing apparatus according to the present invention, when a dropout occurs in an address signal section, the dropout compensation operation is stopped for at least the period during which the dropout occurs.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The figure is a schematic block diagram showing an embodiment of the present invention, in which a reproduced RF signal including an address signal is demodulated by a demodulator 1, amplified by an amplifier 2, and then applied to a switching circuit 3 for dropout compensation. . Also, the reproduced RF signal is
The signal is input to the H delay circuit 4, delayed by IH, demodulated by the demodulator 5, amplified by the amplifier 6, input to the switching circuit 3, and also directly supplied to the dropout detection circuit 7. The dropout detection circuit 7 detects dropouts in the reproduced RF signal and generates a high-level dropout detection signal at least during the dropout occurrence period. This dropout detection signal becomes a one-man power of the two-man gate 8. The output of this AND gate 8 becomes a switching control signal for the switching circuit 3 described above.

The output of the switching circuit 3 becomes a video signal output as it is, and also passes through an LPF 9, an amplifier 10, and a pedestal clamp circuit 11 to a sync separation circuit 12 and an address separation circuit 13.
is input to. An address section detection circuit 14 is provided which detects an address signal insertion section from the synchronization separation output of the synchronization separation circuit 12 and generates a low-level detection signal.The address separation circuit 13 outputs a clamp output during the existence period of this detection signal. address signals are gated and separately derived. Here, since the address signal is inserted within a certain section of the synchronization signal, for example, a vertical blanking period, the address section detection circuit 14 detects the initial timing of the vertical synchronization signal and then The configuration is such that a detection signal of a predetermined width is generated with a time delay. Then, this address interval detection circuit 1
The address section detection signal which is the output of 4 becomes the low input of the two-man AND gate 8.

In this configuration, in a normal operating state without a dropout phenomenon, the dropout detection signal is at a low level and the address section detection signal is at a high or low level, so the output of the AND gate 8 is at a low level. Therefore, if the switching circuit 3 is controlled to select the output of the amplifier 2, then the normal video signal,
A synchronization signal and an address signal will be output.

Next, if a dropout occurs outside the address interval, the dropout detection signal transitions to a high level, and since the address interval detection signal is at a high level, the output of the AND gate 8 becomes a high level, and the switching The circuit 3 selects the output of the amplifier 6 and outputs a signal delayed by 1H to perform dropout compensation.

Furthermore, in the address interval, the address interval detection signal transitions to low level, so even if a dropout occurs in the address interval, the output of the AND gate 8 becomes low level, and the switching circuit 3 selects the output of the amplifier 2. As a result, no dropout compensation operation is performed. Therefore, it is advantageous that incorrect address information or the like is not replaced in the address section.

By the way, if there is a dropout in the address area, part of the data will be destroyed, but dropouts in video disk systems are generally short, so
If compensation is made for this dropout, the signal will be replaced over a longer section than the destroyed portion. In this case, the address signal has no correlation with the data before IH, and the data destruction will further expand, exceeding the code error correction ability and increasing the probability that the data cannot be read.

In other words, since there is a line correlation for video signals, it is possible to compensate for dropouts by replacing them with the pre-IH signal, but in the case of address signals, data will be destroyed regardless of whether compensation is provided. If dropout compensation is not performed, the degree of destruction will be much smaller, and the probability that it will be within the code error correction capability will be higher. Data destroyed by dropout can be compensated for by code error correction, so in the address area, By prohibiting the dropout compensation operation, erroneous information searches can be prevented.

Note that the block diagram shown in the figure merely shows an example, and it goes without saying that various modifications are possible.

As described in detail of the invention, the recorded information reproducing apparatus according to the present invention is configured such that when a dropout occurs in an address signal section, the dropout compensation operation is stopped for at least the period during which the dropout occurs. By doing so, dropouts in address ranges are not replaced with uncorrelated address information, and erroneous information searches can be prevented.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. Explanation of symbols of main parts 3...Signal switching circuit 7...Dropout detection circuit 8...
ANDGATE 14...Address section detection circuit Applicant: Pioneer Corporation Pioneer Video Corporation

Claims (1)

[Scope of Claims] A recorded information reproducing apparatus having a dropout compensation circuit that detects dropouts in a reproduced signal of recorded information including an address signal for information retrieval and performs dropout compensation, the apparatus comprising: Dropout detection means detects and generates a dropout detection signal over at least a dropout occurrence period, and detects a period including an address signal recorded at a predetermined position with respect to a synchronization signal included in the recorded information. detection means for generating an address interval detection signal over the detection period; and gate means for blocking passage of the dropout detection signal only when the address interval detection signal is present; A recorded information reproducing apparatus characterized in that the compensation operation of the dropout compensation circuit is controlled based on the dropout compensation circuit.