JPS5813513Y2 - Time counter starting device in magnetic recording and playback equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a time counter starting device that displays the amount of tape travel in time based on an output signal from a shaft encoder or the like that changes in response to changes in tape speed.

Magnetic recording and playback devices used in recording studios record a large number of audio recordings for each sound source on magnetic tape, so they are multi-channel magnetic recording and playback devices (hereinafter referred to as multi-recorders).
The multi-recorder is equipped with a time counter that displays the amount of time the tape has traveled.

Further, as a feature of the use of the multi-recorder, there is a method of use in which a recorded program is re-recorded at an arbitrary position and the program is edited.

The usage is so-called pan-nine and punch-out, and the usage of pan-nine and punch-out will be briefly explained below.

That is, a recorded multi-channel program can be played back using the recording head (hereinafter referred to as synchronized playback), and recorded by switching from synchronized playback mode to recording mode at any desired position of the desired channel (hereinafter referred to as pan-nine). If you record at any desired position 1,
The recording mode is switched back to the synchronized playback mode (hereinafter referred to as punch-out), and the recording head performs synchronized playback, and the program is edited while repeating the pan-nine and punch-out operations as necessary.

In order to edit a program recorded on a magnetic tape, edit accurately while checking the synchronized playback sound through a monitor speaker and checking the time counter that displays the amount of time the tape has traveled. There is a need.

However, conventional time counters are started by an output signal from a shaft encoder, etc. installed on the same axis of a rotating body, such as a guide roller, whose rotational speed changes in response to changes in tape speed, and is reset while the tape is running. Although the position of the program recorded on the magnetic tape does not change because it is reset to zero by operating a switch, etc.
It had the disadvantage that once the time counter function had stopped, such as changing the magnetic tape, shifting the position when operating the reset switch, or shutting off the power, it was difficult to detect the same position again using the time counter. .

The present invention eliminates the above-mentioned drawbacks and provides a device that can accurately detect the position of a program recorded on a magnetic tape at any time using a mixed signal of rectangular waves having different frequencies recorded on the magnetic tape. An embodiment thereof will be described in detail below with reference to the drawings.

In the vcb shown in FIGS. 1 and 2, rectangular waves having different frequencies f1 and f2 are oscillated by the oscillation circuits 5 and 5', and mixed by the AND gate IC4, f
The waveform will be as shown in 3.

By closing the recording switch 15, the f.
A signal having a waveform of 3 is waveform-shaped by a recording amplifier circuit 3 having a waveform shaping circuit (not shown) as shown at f4, and then recorded on the magnetic tape 1 for a certain period of time by a recording head 2VC.

Among them, a recording time setting circuit (not shown) is included in the recording amplification circuit 3.

The signal f4 recorded on the recording tape 1 for a certain period of time by the recording head 2 is transmitted to the reproduction head 6 as the magnetic tape 1 runs.
Detected from VC.

Since the signal detected by the playback head 6 is very small as shown in f5, the playback amplification circuit 8Vc detects the thick gf of the signal during recording.
The signal is amplified at 4t and input to the detection circuit 9.

The detected signal looks like f6, and is sent to the waveform slicing circuit (
The detected signal f6 is input to and detected by the amplifier circuit 10 (not shown), and its waveform is sliced and further amplified, resulting in a waveform like f7.

Furthermore, the detection circuit 1 has a different time constant from the detection circuit 9 described above.
1, a signal having a waveform of f8 is detected.

The signal f8 detected by the detection circuit 11Vc is further sliced into a waveform f9 and amplified by an amplifier circuit 12VC including a waveform slicing circuit (not shown) having a time constant different from the waveform slicing circuit described above.

Then, the signal f9 is inputted to a reset circuit (not shown) tC in the time counter 13, reset to zero, and started.

14 is a device for detecting magnetic tape running time, which inputs a signal to the time counter 13 according to the tape speed.

For the time counter 13VC that has been reset and started, detecting the starting signal again may cause a malfunction, so a memory circuit (not shown) included in the slice amplifier circuit 12 causes a relay (not shown) to be activated. After the time counter starts by opening the contact circuit γ of the relay, all signals are cut off to prevent malfunction.

The above is an explanation of how to record the starting signal on a magnetic tape on which no time counter starting signal has been recorded and then reproduce it to start the time counter.

In the case of a magnetic tape on which a time counter starting signal has already been recorded by this device, when the starting signal is detected by the playback head 6 and input to the time counter, the time counter is automatically reset and started. .

As mentioned above, according to the device of the present invention, the time counter is started by the signal recorded on the magnetic tape, so even if the time counter function is temporarily stopped, such as by changing the magnetic tape or cutting off the power, the time counter will continue to be displayed. The location of the program being played is always displayed at the same location, allowing you to accurately check the location of the program.

Furthermore, by using rectangular waves having different frequencies as signals, it is possible to distinguish them from signals other than the starting signal, such as voice or music recorded on a magnetic tape, and to prevent malfunctions.

Furthermore, there is an advantage that detection is possible even if the running speed of the magnetic tape is doubled or quadrupled in order to shorten the time required to detect the starting signal.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the device of the present invention;
The figure is an explanatory diagram showing waveforms at each operating circuit position of the device of the present invention. In the figure, 1 is a magnetic tape, 2 is a recording head, 3 is a recording amplification circuit, 4 is an analog IC, 5 and 5' are a square wave oscillation circuit, 6 is a playback head, l is a relay contact, and 8 is a playback amplification circuit. circuit, 9 is a detection circuit, 10 is a waveform slice amplification circuit, 11
9 is a detection circuit with a different time constant, 12 is a waveform slice amplification circuit with a different time constant from 10, 13 is a time counter,
14 is a device for detecting magnetic tape running time, and 15 is a recording switch.

Claims (1)

[Scope of utility model registration request] In a magnetic recording/playback device that has a time counter that displays the amount of tape travel in time using an output signal from a shaft encoder or the like whose rotational speed changes in response to changes in the tape travel speed, rectangular waves with different frequencies are mixed, and A recording device that shapes the waveform of the mixed rectangular wave and then records the waveform-shaped signal onto a magnetic tape for a certain period of time using a recording head, and a playback head that detects the signal recorded on the magnetic tape and outputs the signal. The time counter is reset and started by the output of the detection circuit, which is composed of an amplification circuit, a detection circuit, an amplification and slicing circuit, and a second detection circuit having a different time constant from the detection circuit. A starting device for a time counter in a magnetic recording/playback device.