JPS5952408A - Tape recorder - Google Patents

Abstract

PURPOSE:To exclude address codes from a playback signal and to stop an abnormal sound and the motion of a woofer when there is no signal, by providing a control circuit for opening and closing a switch and a nonsound detecting circuit which sends a signal to said circuit. CONSTITUTION:The nonsound detecting circuit 6 is a circuit which adds, for example, an L-channel and an R-channel signal together and regards as a nonsound period when the level of the sum signal is less than a specific value continuously for a specific time or longer. In the nonsound period, a signal having, for example, a logical level ''1'' is outputted to a control circuit 7. If the sum signal rises above the specific level when the nonsound detecting circuit 5 judges the nonsound period, the circuit is reset and outputs a signal with a logical level ''0'' to the control circuit 7. The control circuit 7 closes a switch 8 in response to the signal of ''1'' to add the L-channel and R-channel signals and generate an address code ''0'', or opens the switch 8 in response to the signal of ''0'' to form a normal reproduction system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder configured to add an L channel signal and an R channel signal during a silent period during playback of a magnetic tape to make it monaural.

Generally, the address code recorded as an absolute address on the tape is a low frequency (below 201; z) outside the audible band.
low level (20nW for OdB-160nWb/m
b/m), and as shown in Figure 3, the L channel and R channel are in opposite phase, and when the bit information is "1" there is a sine wave, and when the bit information is "0" there is no sine wave and it is recorded on the tape. has been done.

□ When playing such a tape normally in a music correspondence system, it is simply passed through a normal NAB equalizer. Even if the address code is reproduced by a music signal system, the main component is outside the audible band, but since the address code is a discontinuous signal as shown in Figure 3, each component appears on both sides of the main component frequency. is expanding. As a result, you can hear a slight abnormal noise coming from the speaker, and you can also see and feel the movement of the speaker's woofer as shown in Figure 3.

Conventionally, in order to remove such an A/R signal, a bypass filter has been provided in the reproduction system as shown in FIG.

In the figure, 1 and 1' are playback heads (the former is for the L channel, the latter with a dash is for the R channel.

The same applies hereafter), 2.2' is a reproduction equalization amplifier, 3.
3' is a bypass filter, 4.4' is a sofa amplifier, and 5 and 5' are speakers. In such a device, the characteristics of the bypass filters 3, 3' significantly attenuate the address code and also reduce the movement of the woofer.

However, recent music playback systems are low frequency (201
1z), and the music signal itself contains frequency components in the vicinity. Therefore, the cutoff frequency of the bypass filter must be quite low, and it is also desired to have steep characteristics, but even in that case, the address code would theoretically not be O.

The object of the present invention is to overcome the drawbacks of the above-mentioned conventional systems,
To provide a tape recorder capable of removing an address code from a reproduced signal using a bypass filter, and stopping abnormal noise during silent signal waiting and movement of a woofer.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 2 is a program diagram of a reproduction system of a tape recorder according to an embodiment of the present invention.

, as shown in the figure, a switch 8 is provided between the reproduction equalizer amplifier 2°2' and the frequency amplifiers 4, 4' to connect and disconnect the L channel and the R channel via a resistor R9R'. ing. This switch 8 is opened and closed by a control circuit 7. The control circuit 7 receives a signal from the silence detection circuit 6 provided in parallel with the reproduction equalizer amplifiers 2, 2'.

Next, the operation of the system shown in FIG. 2 will be explained.

The signals reproduced by the reproduction heads 1 and 1 pass through reproduction equalizer amplifiers 2 and 2', pass through amplifiers 4 and 4', and reach speakers 5 and 5'.

The reproduced signal is also input manually to the silence detection circuit.

For example, the silence detection circuit 6 adds the I-channel signal and the R-channel signal, and if the sum signal is at a certain specified layer) and continues for more than a certain set time, it is configured to detect the signal as silence. It is a circuit.

When the silence occurs, a logic "t" signal is output to the control circuit 7. Also, when the jli% sound detection circuit 5 determines that there is no sound, if the sum signal level reaches a specified level or higher, it is reset and the logic "0" is reached.
A '' signal is sent to the control circuit 7.

In the control circuit 7, when it is "1", switch 8 is closed and the L channel signal and R channel signal are added to set the address code to O (see Figure 3), and when it is "0", switch 8 is closed. Open it and start playing normally.

In the above embodiment, cent: silence detection, recesso 1~
:Although sound detection is used, the following may also be used.

■ Set: Silence detection Reset Detection of end of near address code or presence of sound ■ Cent: Detection of silence and start of address code Reset: Detection of sound ■ Set: Detection of silence and start of address code Recesso 1- 2. Detection of sound or end of address code However, when detecting the beginning or end of an address code, a separate detection circuit must be provided for that purpose.

Further, in this embodiment, the switch 8 is connected between the reproduction equalizer amplifiers 2, 2' and the Batzer amplifiers 4, 4', but it may be connected to any of the reproduction systems.

As explained above, according to the present invention, when there is no sound, the address code of the L channel and the address code of the R channel are logically added to 0. Any abnormal movement of the woofer that you feel is completely gone. Also, at this time, it becomes a monaural signal, but there is no sound at most during that period.

Since it is a time, the music signal will never be monaural.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional system, FIG. 2 is a block diagram of a reproduction system of a tape recorder according to an embodiment of the present invention, and FIG. 3 is a waveform diagram of an address code. 6... Silence detection circuit, 7... Con I
・Roll circuit, 8...Switch. Patent applicant Pioneer Corporation

Claims (1)

[Claims] A tape recorder comprising a playback system of the tape recorder which is provided with a switch for connecting and connecting an L channel and an R channel, a control circuit for opening and closing the switch, and a silence detection circuit for sending a signal to the control circuit.