JPH02192075A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain the regeneration signal small in lack of edges and distortion by providing a logarithmic stretcher to stretch an FM demodulating signal between an FM demodulator and a deemphasis circuit. CONSTITUTION:An FM demodulator 7 is provided to demodulate a reproducing FM signal and a logarithm stretcher 8 is provided to stretch the FM demodulating signal. Then, a deemphasis circuit 9 is provided to restore an output signal from this logarithm stretcher 8 to an original signal. Thus, at the time of reproducing, the signal to be FM-demodulated by the FM demodulator is inputted to the logarithm stretcher and stretched and after that, the signal is passed through the deemphasis circuit. Accordingly, since the signal is cut off by a clipper at the time of recording and a waveform, to which logarithm compression is executed, can be stretched, the reproducing signal of the small lack of the edge and small distortion can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a recording/reproducing apparatus such as a video tape recorder, and more particularly to a reproduction signal processing circuit.

[Prior Art] Fig. 5 is a block diagram showing the configuration of a signal processing system of a conventional magnetic recording/reproducing apparatus. Emphasize. (2) uses a clipper to limit the amplitude of the video signal (B) outputted from the pre-emphasis circuit (1) by cutting off the signal components above the negative range. (3) is an FM modulator that performs FM modulation on the amplitude-limited video signal (C).

(4) is a recording amplifier, (5) is a magnetic tape, and the above constitutes a signal processing system for video signals.

(6) is a playback amplifier, (7) is an FM demosulator,
The FM modulation signal (F) reproduced from the magnetic tape (5) is amplified, and the amplified signal CG) is FM demodulated.

(9) is a de-emphasis circuit which restores the FM demodulated signal (H) to the original video signal (J). The above constitutes a video signal reproduction processing system.

Figure 6 shows an example of the configuration of the clipper (2), which includes a resistor (R), two diodes (DI), (D2) and a DC voltage source (V
1) and (V2) - This is a type of boat fishing.

Next, the operation of the above configuration will be explained.

A recorded video signal (A
) is first input to the pre-emphasis circuit (1).

The pre-emphasis circuit (1) emphasizes high frequency components, and the video signal (B), which has a waveform as shown in (15) in FIG. 4, is input to the clipper (2). This clipper (2) cuts off signal components having an amplitude above a certain certain level and limits the amplitude, resulting in a signal waveform as shown in (10) in FIG. Therefore, the amplitude limited video signal (C
) is input to the next stage FM modulator (3) and subjected to FM modulation. The FM wave signal (D) output from the FM modulator (3) is recorded on the magnetic tape (5) as an FM modulation signal (E) via a recording amplifier (4) and a magnetic head (not shown).

Next, during reproduction, the FM modulation signal (E) recorded on the magnetic tape (5) is reproduced via the magnetic head,
After the signal (F) is amplified to a sufficient amplitude by the reproduction amplifier (6), the amplified signal (G) is FM demodulated by the FM demosimulator (7), and then by the de-emphasis circuit (9). The reproduced video signal (J) having a waveform as shown in FIG. 3 (12) is restored and output.

[Problem to be Solved by the Invention] Conventional recording and reproducing devices are configured as follows, so that the reproduced signal processing system can completely restore the signal components that are amplitude-limited and clipped by the clipper during recording. Can not do it. As a result, the playback signal had the disadvantage of becoming a distorted signal with missing edges.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a recording/reproducing apparatus that can obtain a reproduced signal with less edge loss and less distortion.

[Means for Solving the Problems] A recording/reproducing apparatus according to the present invention is characterized in that a logarithmic expander for expanding an FM demodulated signal is provided between an FM demodulator and a de-emphasis circuit.

[Function] According to the present invention, during playback, the signal demodulated by the FM demodulator is input to the logarithmic expander and expanded, and then passed through the de-emphasis circuit, so that the signal is not scraped off by the clipper during recording. Since it is possible to expand a logarithmically compressed waveform, a reproduced signal with less edge loss and less distortion can be obtained.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of a signal processing system of a magnetic recording/reproducing apparatus according to an embodiment of the present invention. Since it is the same as the example, the same reference numerals are given and the explanation thereof will be omitted.

In FIG. 1, a logarithmic expander (8) is interposed between an FM demodulator (7) and a de-emphasis circuit (9) to expand the FM demodulated signal.

Next, the operation of the above configuration will be explained.

A recorded video signal (8) having a waveform as shown in (14) in FIG. 4 is first input to a pre-emphasis circuit (1).

The pre-emphasis circuit (1) emphasizes high frequency components, and the video signal (B), which has a waveform as shown in (15) in FIG. 4, is input to the clipper (2). This clipper (2) cuts off signal components having a certain amplitude or more, resulting in a signal waveform as shown in (10) in FIG.

Then, the amplitude-limited video signal (C) undergoes FM modulation in the next stage FM modulator (3), and then the FM wave signal (D) is transmitted to the magnetic tape (D) via the recording amplifier (4) and the magnetic head. 5) is recorded.

On the other hand, during reproduction, the FM modulated signal (F) picked up by the magnetic head is amplified by a reproduction amplifier (6), and the amplified signal (G) is subjected to FM demodulation by an FM demodulator (7). The waveform after this FM demodulation becomes a waveform similar to (C) during recording, that is, (lO) in FIG. 2. Then, by inputting this signal (11) to a logarithmic expander (8), it is expanded into a waveform as shown in (11) in FIG. During recording, the signal waveform clipped by the clipper (2) has a logarithmically compressed waveform due to the characteristics of these elements. Therefore, by performing logarithmic expansion, which is the opposite of logarithmic compression, at the time of reproduction, the original video signal with small distortion approaching (15) in FIG. 4 will be reproduced.

Although the -J2 embodiments show signal processing of a magnetic recording/reproducing device such as a video tape recorder, the recording medium is not limited to magnetic.

[Effects of the Invention] As described above, according to the present invention, since a logarithmic expander is added to the reproduced signal processing system, it is possible to reduce edge loss in the reproduced signal and reduce distortion. This has the effect of achieving high regeneration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a signal processing system of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram of an input signal to a de-emphasis circuit, and FIG. 3 is a waveform diagram of a reproduced video signal. , FIG. 4 is a waveform diagram of the recorded video signal and the output signal of the pre-emphasis circuit, FIG. 5 is a block diagram showing the configuration of a signal processing system of a conventional magnetic recording/reproducing device, and FIG. 6 is a configuration showing an example of a clipper. It is a diagram. (1)...Pre-emphasis circuit, (2)...-clipper, (3)...FM modulator, (7)...FM
Demosimulator, (8)...logarithmic expander, (9)・-
・De-emphasis circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A pre-emphasis circuit that emphasizes the high-frequency components of the recorded signal, a clipper that cuts off signal components above a certain amplitude of the output signal from the pre-emphasis circuit, an FM demodulator that demodulates the reproduced FM signal, and the FM demodulated signal. 1. A recording/reproducing apparatus comprising: a logarithmic expander for expanding the logarithmic expander; and a de-emphasis circuit for restoring the output signal from the logarithmic expander to the original signal.