JPS6386132A - Detecting circuit for program searching signal - Google Patents

Abstract

PURPOSE:To obtain a stable program searching state by switching a time constant for detecting a program searching signal to match a reproducing speed of a signal, and outputting a release signal by a timing being suitable for each reproducing speed. CONSTITUTION:When a device operation is in a standard mode, a diode D becomes OFF, and in accordance with an output of a program searching signal detecting circuit 2, a release signal R is outputted from a program searching controlling circuit 3, and by a suitable timing, a program searching operation is switched to a reproducing operation. Also, at the time of a triple-speed mode, an output of a switching circuit 4 becomes H, the diode D becomes ON, a time constant R3.C of a time constant circuit 2a becomes 1/3 of (R2+R3).C, the release signal R is outputted, and a program searching operation is released and shifted to a reproducing state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cue signal detection circuit for a magnetic recording/reproducing device.

[Prior Art] FIG. 3 is a block diagram of a conventional cue detection circuit, in which the signal detection circuit is shown, and (3) is a cue control circuit.

Next, the operation will be explained.

When the magnetic recording/reproducing device is in the cueing operation state in standard speed playback mode (hereinafter referred to as "standard mode"), the audio output detection circuit (1) outputs "H" when detecting an audio signal. When no level or audio signal is detected, a detection signal at the rLJ level is continued to be output, and the point at which the detection signal changes from the rHJ level to the rLJ level becomes a signal indicating the end point of a series of audio signals.

This detection signal is input to the transistor Tr of the five-head signal detection circuit (2), and while it is at the rLJ level, the time constant circuit (2) consisting of the capacitor C and the resistor R1
A voltage ■cc is applied to the capacitor C in a) via the resistor R1, and the potential Vc of the capacitor C is increased by the time constant C·R1 as shown in FIG. 2(a).
3) When Vc reaches a predetermined value Vs, the recording/re-recording/playback device outputs the cueing operation and outputs R, and shifts from the operating state to the standard operating mode playback state. . In this case, the time constant C・R1 of the 1 time constant circuit (2a) is
It is set so that Vc becomes Vs in a time T shorter than the running time of the portion of the magnetic tape where no audio signal is recorded, and the next recorded audio signal is played back from the beginning.

[Problems to be Solved by the Invention] Since the conventional cueing signal detection circuit is configured as described above, it outputs the release signal R after the time T regardless of the playback mode of the magnetic recording/playback device. Cueing is performed normally in this mode, but in other playback modes, such as playback mode at 3x speed (hereinafter referred to as ``3x speed mode''),
) Sometimes, the magnetic tape would go into playback mode after it had gone too far, causing the problem that the beginning of the audio output would be cut.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a cueing signal detection circuit that can perform cueing detection suitable for the reproduction mode of a magnetic recording and reproducing apparatus.

[Means for Solving the Problems] The cueing signal detection circuit according to the present invention includes means for switching the delay time during which the canceling signal is output from the cueing control circuit in accordance with the playback mode of the magnetic recording and reproducing device. It is something.

[Function] The cueing signal detection circuit according to the present invention switches the time constant of the time constant circuit according to the playback mode, so that the portion of the magnetic recording medium where the signal to be played back is not recorded passes through the playback head. Since the release signal R is sent from the cue control circuit at an appropriate timing before the end of the playback and the mode is switched to the playback mode, the playback signal will not be cut off.

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

In white, the same symbols as in Fig. 3 indicate the same or corresponding parts, respectively.1 The time constant circuit (2 &) is composed of a series resistor R2 and R3 and a capacitor C, and the time constant (R2 + R3)・C is The value is the same as R1.C in FIG. 3, and R3.C is set to the value of the station R1.C. (4
) is a mode switching circuit, the output is "L" level in standard mode, the diode D connected to the connection point A of resistors R2 and R3 is OFF, and the output is rHJ in triple speed mode.
At this level, the diode D is turned on, and the potential at the connection point A is set to Vcc, and the time constant of the time constant circuit (2a) is switched to R3.C.

Next, the operation will be explained.

The operation when the magnetic recording/reproducing device is in standard mode is as follows.
Diode D is in the OFF state, and (R2+R3)・C
= R1-C, the voltage Vc of the capacitor C rises with the time constant shown in Fig. 2(a), and 1
After time T, Vs is reached and a release signal R is output from the cueing control circuit (3), and the cueing operation is switched to the playback operation at an appropriate timing.

However, in 3x speed mode, the number of modes to be switched/W
^ Output true +, May 1. Shikappu I No Poison D
is turned on, and the potential at point A becomes Vcc. Therefore,
The time constant R3・C of the time constant circuit (2a) is (R2+13
)・C, so as shown in Figure 2 (b),
Vc reaches Vs after time T/3, and at this time, the cueing control circuit (3) outputs a release signal R, and the magnetic recording/reproducing apparatus cancels the cueing operation and shifts to the reproduction state.

In this way, according to this embodiment, not only in the standard mode but also in the triple speed mode.

Since the cueing operation is switched to the playback state at an appropriate timing, the beginning of the playback signal will not be cut off.

In addition, although the above embodiment shows the case where there are two types of magnetic tape running speeds, even when there are multiple types of tape running speeds,
A similar effect can be obtained by configuring the time constant circuit (2a) to switch the time constant depending on the tape speed.

Further, although the above embodiment has been described using a magnetic recording/reproducing device that records audio signals on a magnetic tape, the signals to be reproduced are not limited to audio signals.
Furthermore, in addition to magnetic tape, other recording media such as magnetic disks can be used as the magnetic recording medium, and similar effects can be obtained.

[Effects of the Invention] As described above, according to the present invention, the time constant of the time constant circuit of the cue signal detection circuit is switched according to the reproduction speed of the reproduction signal, and the release signal is applied at a timing appropriate for each reproduction speed. Since I configured it to output, regardless of the playback speed,
This has the effect of providing a stable cueing state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a waveform diagram of the output voltage Vc of a time constant circuit, and FIG. 3 is a block diagram of a conventional cue detection circuit. (1)...Audio output detection circuit, (2)...Cutting signal detection circuit, (2a)...Time constant circuit, (3)...
... Cue control circuit, (4) ... Mode switching circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Means for monitoring the presence or absence of a reproduction signal during cueing operation of a magnetic recording and reproducing device and outputting a detection signal when the reproduction signal is interrupted, a time constant circuit that starts operation in response to this detection signal, and a time constant circuit that starts operation based on this detection signal. means for switching a time constant of a circuit to a time constant corresponding to a reproduction mode of the reproduction signal; and a means for canceling the cueing operation of the magnetic recording and reproduction device when the output voltage value of the time constant circuit reaches a predetermined value for reproduction. A cueing signal detection circuit comprising means for transitioning to operation.