JPS63222306A - Magnetic recording and reproducing medium - Google Patents

Abstract

PURPOSE:To permit surer change-over and to facilitate a handling operation by demodulating and holding the part of a reproduction FM signal corresponding to a synchronizing signal and discriminating a frequency set mode at the time of recording at an output level, thereby changing over a reproduction signal processing circuit. CONSTITUTION:The part corresponding to the synchronizing circuit of the FM signal taken out by a gate circuit 21 at the time of reproduction is demodulated by an FM demodulation circuit 22 and the demodulated DC voltage is held in a sample holding circuit 23. The output level from the circuit 23 is converted to a low level in a normal mode and to a high level in a high-band mode, by which an FM equiv. circuit 4, an FM demodulation circuit 7, a deemphasis circuit 8, and a low-pass filter 9 are automatically changed over so as to have the optimum characteristics according to respective modes.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is equipped with a means for switching the FM frequency setting into multiple stages during recording, and when playing back, the optimum characteristics are set according to the setting mode during recording. The present invention relates to a magnetic recording/reproducing device configured to process a reproduced signal.

[Prior Art] Fig. 2 is a block diagram showing a reproduction signal processing circuit in a conventional magnetic recording/reproduction device.
is the video head, (1B) is the rotary transformer, (2) is the head amplifier circuit, (3) is the FM-AGC circuit, (4)
is the FM equivalent circuit, (5) is the dropout compensation circuit,
(6) is a limiter circuit, (7) is an FM demodulation circuit, (
8) is a de-emphasis circuit, (9) is a low-pass filter, and (10) is a luminance signal and chroma signal mixing circuit (
(hereinafter referred to as a Y/C mixing circuit), (11) is an output terminal for a video output signal, and (12) is a switch that is switched according to the FM frequency setting at the time of recording.

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

The signal recorded on the magnetic tape is picked up by a video head (IA), passed through a rotary transformer (IB), and amplified by a head amplifier circuit (2), whose output is FM-
The AGC circuit (3) suppresses variations in the playback output of the head. Next, the frequency characteristics and phase characteristics are optimized in the FM equivalent circuit (4). Next, a dropout compensation circuit (5) compensates for the dropout of the FM signal caused by scratches or dust on the magnetic tape, and the amplitude is limited by a limiter circuit (6).

Subsequently, the video signal subjected to FM demodulation in the FM demodulation circuit (7) is subjected to de-emphasis processing in a de-emphasis circuit (8) with characteristics opposite to the pre-emphasis characteristics at the time of recording. Furthermore, the band is limited by a low-pass filter (9), and mixed with a chroma signal processed by a chroma signal processing circuit (not shown) in a Y/C mixing circuit (10) to form a composite video signal, which is sent to an output terminal (11). is output from.

At this time, the FM Equivalent circuit (4), limiter circuit (6), demodulation circuit (7),
De-emphasis circuit (8), low-pass filter (9)
is switched to a characteristic corresponding to both of the above modes.

[Problems to be Solved by the Invention] Since the conventional magnetic recording/reproducing device is configured as described above, if the FM frequency setting is switched to any one of multiple levels during recording and recorded, even during playback. , it is necessary to switch the playback signal processing circuit so that signal processing with optimal characteristics can be performed in accordance with the setting mode at the time of recording, but such switching must be performed manually via the switch (12). There were some inconveniences.

This invention was made to solve the above-mentioned problems, and when playing back, it automatically ensures that the playback signal processing circuit is in the optimal state in accordance with the FM frequency setting mode during recording. The object of the present invention is to provide a magnetic recording/reproducing device that can switch to

[Means for Solving the Problems] A magnetic recording and reproducing apparatus according to the present invention demodulates a portion of a reproduced FM signal corresponding to a synchronizing signal, and includes a circuit that holds the demodulated voltage, and adjusts its output level. The present invention is characterized in that it is configured to automatically determine the frequency setting mode during recording and to switch the reproduction signal processing circuit.

[Operation] According to the present invention, during reproduction, the FM signal of the synchronization signal portion of the reproduced FM signal is extracted, FM demodulated, and its DC voltage is held.

Then, the FM frequency setting mode at the time of recording is automatically determined based on the output level from the holding circuit, and based on the result of the determination, reproduction is performed with the optimum characteristics for the setting mode at the time of recording.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing a reproduction signal processing circuit of a magnetic recording and reproducing apparatus according to an embodiment of the present invention. In the same figure, the configuration from the video head (IA) to the video output terminal (11) is shown in FIG. Since the configuration is the same as that of the conventional example shown in , the same reference numerals are given and the explanation thereof will be omitted.

In Figure 1, (20) is a synchronous separation circuit, low, -
-4+ no ox/n8 h town-m head office t
l Decoy C ÷ 1 Naka-shi'; Go Tato l S Extract the synchronization signal from the lips. (21) is a gate circuit which manually inputs the reproduced FM signal amplified by the head amplifier circuit (2), is gated by the synchronization signal, and transmits the FM signal corresponding to the synchronization signal portion to the second stage of the next stage. FM demodulation circuit (2
Add to Z). This FM demodulation circuit (22) performs FM demodulation of the synchronization signal portion. (23) is a sample and hold circuit that holds the DC voltage of the FM demodulated signal.

The FM equivalent circuit (4), the first FM demodulation circuit (7), the de-emphasis circuit (8), and the low-pass filter (9) are configured to be controlled by the output voltage from the sample and hold circuit (23). .

The operation of the above configuration will be explained.

During reproduction, the frequency of the reproduced FM signal corresponding to the synchronization signal extracted by the gate circuit (21) is, for example, 3.4 MHz in normal mode and 5 MHz in high band mode.
．． It has been selected as 0MH2. The reproduced FM signal having such a frequency is demodulated by the FM demodulation circuit (22), and an output voltage corresponding to each mode is obtained. The DC 7
One voltage is held in the sample and hold circuit (23) for one horizontal period. The output level from this sample and hold circuit (23) is converted to low level in normal mode and high level in humbant mode, and is converted to FM equivalent circuit (4), first
FM demodulation circuit (7), de-emphasis circuit (8),
The characteristics of the low-pass filter (9) are automatically switched to be optimal according to each mode.

In the above embodiment, the reproduced FM signal is taken out from the output of the head amplifier circuit (2), but it may be taken out from any point up to the FM demodulation circuit (7).

In addition, in the embodiment described above, a configuration is shown in which the DC voltage of the synchronization signal portion is held in the sample and hold circuit (23).
A configuration may also be adopted in which a smoothing circuit is provided to maintain the DC voltage.

[Effects of the Invention] As described above, according to the present invention, the frequency setting mode during recording is automatically determined during playback, and the playback signal processing circuit is configured to have optimal characteristics according to each mote. Since automatic switching is possible, it eliminates the inconvenience of having to manually switch the processing circuit after the user confirms that there is a problem during playback, and has the effect of greatly simplifying handling operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a reproduction signal processing circuit in a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a reproduction signal processing circuit in a conventional magnetic recording/reproducing apparatus. (4) -F M equivalent circuit, (6)... limiter circuit, (7), (22)... demodulation circuit, (8)... de-emphasis circuit, (9)... low-pass filter , (20)...Synchronization separation circuit, (21)...Gate circuit, (23)...Sample and hold circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) In a magnetic recording/reproducing device equipped with means for switching the FM frequency setting to multiple stages during recording,
A circuit that FM demodulates the part corresponding to the synchronization signal of the M signal, a circuit that holds the demodulated DC voltage, and the FM frequency setting during recording is automatically determined based on the output level from the voltage holding circuit. 1. A magnetic recording and reproducing apparatus comprising: means for switching a reproduction signal processing circuit.