JPH0450711Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a video disc data reading circuit.

[Prior art]

Conventionally, there is a video disc data reading circuit shown in FIG. 2, which reads data recorded on a VHD language disc into, for example, a video signal processing circuit of a video disc player. This conventional video disc data reading circuit includes a pickup 1 that reads a recorded signal of a video disc (not shown), a video signal demodulation circuit 2 that demodulates the read recorded signal into a video signal, and a horizontal synchronization signal that is extracted from this video signal. A horizontal synchronization separation circuit 3 separates a horizontal synchronization signal, a synchronization clock generation circuit 4 receives a horizontal synchronization signal and generates a synchronization clock having the same phase as the horizontal synchronization signal using a phase lock circuit (PLL), and a vertical synchronization signal is input from the video signal. a vertical synchronization separation circuit 5 that separates the data from the video signal; a counter 6 that counts the synchronization clock of the synchronization clock generation circuit 4 and outputs a data string end position signal at the same time as it is reset by the vertical synchronization signal; A digital data demodulation circuit 7 separates and demodulates the digital data that is already stored, and a digital data demodulation circuit 7 that sequentially inputs this digital data and interrupts the input of new digital data every time a data string end position signal is input and demodulates the already stored digital data. , and an error correction circuit 9 that inputs digital data from the register 8.

However, in such conventional video disc data reading circuits, high accuracy is required in separating the vertical synchronization signal, which is the reference for the timing at which the data string end position signal is output.
Vertical synchronization signals may not be completely separated due to noise, etc., making it impossible to read data.

[Purpose of invention]

The present invention has been developed in view of the above-mentioned circumstances, and even when the vertical synchronization signals cannot be separated sufficiently, the data string end position signal can be reliably obtained and the above-mentioned failure to read data can be prevented. The purpose of this invention is to provide a video disc data reading circuit.

[Structure of the idea]

In order to achieve the above objectives, the present invention
The digital data separated from the video signal obtained from the video disk via pickup is sequentially stored in a register, and the input of data to the register is stopped by a data string end position signal, and the data that has already been input is corrected for errors. In the video disc data reading circuit that outputs to the circuit,
a first data string end position signal forming means for forming a data string end position signal from a vertical synchronization signal separated from the video signal; and a first data string end position signal forming means for forming a data string end position signal from a horizontal synchronization signal separated from the video signal and a previous data string end signal. A second data string end position signal forming means for forming a data string end position signal is connected to the first data string end position signal forming means to the register at the time of startup and when an error occurs, and after the connection, the data string ends. The video disc data reading circuit is characterized in that a switch means is provided for connecting the second data string end position signal forming means after the data string end position signal is output from the position signal forming means.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a video disc data reading circuit according to an embodiment of the present invention. This video disc data reading circuit includes a pickup 1 that reads a recorded signal of a video disc (not shown), a video signal demodulation circuit 2 that demodulates the read recorded signal into a video signal, and a horizontal synchronization signal that is separated from this video signal. Horizontal synchronization separation circuit 3 and horizontal synchronization signal input, phase lock circuit (PLL)
A synchronization clock generation circuit 4 that generates a synchronization clock having the same phase as the horizontal synchronization signal, a vertical synchronization separation circuit 5 that separates the vertical synchronization signal from the video signal, and a first data string end position signal forming means, A counter 6 that counts the synchronous clock of the synchronous clock generating circuit 4 and outputs a data string end position signal at the same time as it is reset by the vertical synchronous signal, and a digital data that separates and demodulates the digital data mixed with the video signal. a demodulation circuit 7, a register 8 which sequentially inputs this digital data, interrupts the input of new digital data every time a data string end position signal is input, and outputs the already stored digital data; The error correction circuit 9 inputs digital data from the computer.

Further, the video disc data reading circuit inputs and counts the synchronization clock during one vertical period, and counts the same number as the number of horizontal synchronization signals during one vertical period. A counter 10 is a second data string end position signal forming means that outputs a data string end position signal when the data string ends, and a switch circuit 11 switches the input destination of the data string end position signal input to the register 8.
It is equipped with Further, the error correction circuit 9 determines whether or not the data string end position signal, which is a reference for data transfer from the register 8, is output at the correct timing, and when it is correct, outputs a switch switching signal, and the second A data string end position signal of the counter 10, which is a data string end position signal forming means, is outputted to the switch circuit 11 so as to be applied to the register 8. When this switch switching signal is not output, that is, when the data string end position signal is given to the register 8 at the wrong timing before the first data string end position signal is output, and a so-called multiple error occurs. The switch circuit 11 is configured to automatically return to supply the data string end position signal of the counter 6, which is the first data string end position signal forming means, to the register 8. The reset port of the counter 10, which is the second data string end position signal forming means, is connected to the data string end position signal input terminal of the register 8.
The counter 10 is configured to be reset by a data string end position signal output from 0.

According to the video disc data reading circuit configured in this manner, the counter 6 serving as the first data string end position signal forming means is connected to the register 8 via the switch circuit 11 at the time of startup and when an error occurs; After that connection this counter 6
After a data string end position signal is output from , if the data string end position signal is input at the correct timing, the error correction circuit 9 outputs a switch switching position signal, and the switch circuit 11 is switched to the second position. A counter 10 serving as a data string end position signal forming means is connected to the counter 6. Therefore, the signals other than the first data string end position signal and the data string end position signal immediately after the multiplex error occur are not based on the vertical synchronization signal.
The data string end position signal formed based on the horizontal synchronization signal, which is separated more reliably than this, can be input to the register 8, and even if the vertical synchronization signal cannot be detected due to noise etc., accurate timing can be obtained. The data string end position signal is sent to register 8.
It is possible to input the information to

[Effect of idea]

As described above, according to the present invention, signals other than the first data string end position signal and the data string end position signal immediately after the occurrence of a multiplex error are separated more reliably without being based on the vertical synchronization signal. The data string end position signal formed based on the horizontal synchronization signal can be input to the register, and even if the vertical synchronization signal cannot be detected due to noise etc., the data string end position signal can be input to the register at accurate timing. It is possible to input the information. As a result, it is possible to significantly reduce the possibility that reading becomes impossible due to loss of the data string end position signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video disc data reading circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional video disc data reading circuit. 1...Pickup, 2...Video signal demodulation circuit, 3...Horizontal synchronization separation circuit, 4...Synchronization clock generation circuit, 5...Vertical synchronization separation circuit, 6...Counter (first data string end position signal forming means),
7... Digital data demodulation circuit, 8... Register, 9... Error correction circuit, 10... Counter (second data string end position signal forming means), 11...
...Switch circuit (switch means).

Claims (1)

[Scope of utility model registration request] The digital data separated from the video signal obtained from the video disk via pickup is sequentially stored in a register, and the input of data to the register is stopped by a data string end position signal, and the data that has already been input is corrected for errors. In a reading circuit for video disc data outputted to a circuit, a first data string end position signal forming means for forming a data string end position signal from a vertical synchronizing signal separated from the video signal; second data string end position signal forming means for forming a data string end position signal from the horizontal synchronization signal and the previous data string end signal; A switch means is provided for connecting the signal forming means and connecting the second data string end position signal forming means after the data string end position signal is output from the data string end position signal forming means. A video disc data reading circuit.