JPS6035888A - Rotary head type magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To discriminate whether a PAL signal or an NTSC signal easily by judging a reproduced signal on the basis of a detected output from a counter. CONSTITUTION:The counter 9 counts up horizontally synchronizing signals in one field period repeatedly, and if the counted value exceeds a set value, generates an output. Therefore, whether the reproduced signal is a PAL signal or an NTSC signal can be judged by detecting the existence of the output generated from an output terminal 11 in every one-field period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating head type magnetic recording/reproducing device (VTR), in which the signals recorded during playback are NTSC.
C format television signal (hereinafter referred to as NTSC' signal)
Or PAL television Shingetsu (PAL signal)
It is possible to automatically detect whether the signal is the same or not, and to switch various functions of the VTR to suit each signal.

Conventionally, VTRs have been considered that can selectively switch between NTSC and PAL signals and record and play back NTSC and PAL signals.
.

When playing back a recorded magnetic tape in such a VTR, it is important to check whether the recorded signal on the tape is an NTSC signal or not.
I) It is necessary to switch each circuit of the VTR depending on whether the signal is a PAL signal or not.

The present invention is intended to automatically detect which of the above-mentioned signals a recorded signal is during playback, and one embodiment thereof will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a hesodon cylinder having a magnetic head 2.3, which is rotationally driven by a motor 4.
6 is a rotational phase detection device having a conventionally known configuration and detecting a signal indicating the rotational phase of the magnetic head 2.3;
The detection signal (FIG. 2A) is applied to the next head switching signal generation circuit 6, and a head switching signal port is generated. This head switching signal port is applied to the switching circuit 7,
It is constructed so that the reproduced signals from the magnetic heads 2 and 3 are taken out alternately and guided to the output terminal 14 as a continuous signal.

A part of the head switching signal port is applied to a multiplier circuit 8, and a signal C is generated in response to the rising and falling edges of the signal port. In other words, this signal C is generated every one field period, and is used as a reset signal by the counter 9.
is applied to The number of horizontal synchronization signals separated from the reproduced signal by the synchronization separation circuit 10 is applied as a clock signal to the counter 9, and is sequentially counted. The counter 9 has a count value between 312.5, which is the number of horizontal synchronizing signals within one field period of a PAL signal, and 262.5, which is the number of horizontal synchronizing signals within one field period of an NTSG signal. The configuration is such that when a count of 288 or more is counted, an output E is generated at the output terminal 11.

The J-counter 9 is configured to repeatedly count the horizontal synchronizing signal for one field period of the reproduced signal, and to generate an output if the counted value is 288 or more.
By detecting the presence or absence of output for each field period that occurs in 1, it is possible to determine whether the signal being reproduced is a PAL signal or not.
It is up to you to determine whether it is a signal or not.

That is, if the retrigger monostable multipipe rake 12 is driven by the output of the output terminal 11, if the reproduced signal is a PAL signal, an output is generated at the output terminal 11 for each field. vibrator 12
At the output end 13 of.

A predetermined output indicating that there is a PAL signal is obtained, and conversely, when the reproduced signal is an NTSC signal, the output terminal 11 is output.
As described above, according to the present invention, it is possible to easily determine whether a reproduced signal is a PAL signal or an NTSC signal with a simple configuration. Note that when playing back a signal as a steal, slow motion, or quick motion image by changing the tape speed from the tape speed during recording, there may be a slight error in the number of horizontal synchronization signals between the head switching signal ports. However, if the set value of the counter is set approximately in the middle of the number of regular horizontal synchronization signals of both signals, there is no problem.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the rotary head type magnetic recording/reproducing apparatus of the present invention, and FIG. 2 is an explanatory diagram of the same operation. 1...Head cylinder, 2.3...Magnetic head.

Claims (1)

[Claims] synchronizing signal separating means for separating a horizontal synchronizing signal from a reproduction signal from a rotating magnetic head; means for generating a detection signal corresponding to a rotational phase of the rotating magnetic head; a counter that sequentially counts horizontal synchronization signals, and a count value of the counter is between the number of horizontal synchronization signals of the PAL television signal and the number of horizontal synchronization signals of the NTSC television signal during the repetition period of the detection signal; and detecting means that generates an output upon detecting that a predetermined value has been reached, and depending on whether the output of the detecting means is present or not, the reproduced signal is determined to be a PAL television signal or an NTSC television signal. A rotary head type magnetic recording and reproducing device characterized by determining whether the signal is a signal or not.