JPS60160005A - Magnetic tape reproducer - Google Patents

Abstract

PURPOSE:To know the type of a magnetic tape and to attain the automatic switching to a state according to the type of the using tape, by cutting off signals in response to the presence or absence of signals on the right and left signal paths of a magnetic tape respectively. CONSTITUTION:A detection circuit 31 produces H and L signals to output terminals 31c and 31d when input terminals 31a and 31b are set at L and H respectively, the L and H signals to output terminals 31c and 31d when terminals 31a and 31b are set at H and L respectively, and the L signal to terminals 31c and 31d when terminals 31a and 31b are set at H. Therefore the output of the circuit 31 is set at H when waveform shaping circuits 29 and 30 are set at H. Thus signal circuits 27 and 28 have no actuation and therefore the stereo reproduction is carried out. While the output signal of a preamplifier 25 is first set at H to actuate the circuit 28 in a reproduction mode of a sound multiplex recording tape where the play and music signals are recorded to the right and left channels respectively. Thus the music signal, i.e., the output signal of a preamplifier 26 is cut off, and only the play signal is delivered.

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to a magnetic tape playback device suitable for use in a karaoke machine, and in particular a magnetic tape playback device that automatically selects between a stereo recording tape and an audio multiplex recording tape. The present invention relates to a magnetic tape reproducing device capable of reproducing a magnetic tape.

(B) Prior Art A device (commonly known as a karaoke device) is known that can reproduce a performance signal recorded on a magnetic tape and sing a song in accordance with the performance signal. This device mixes the performance signal obtained from the magnetic tape playback device with the singing signal obtained from the microphone and emits the sound from the speaker, making it possible to easily enjoy singing even without live music.
Currently widely used.

By the way, currently available magnetic tapes for karaoke include stereo recording tapes in which the left stereo signal is recorded on the left channel track of the magnetic tape, and the right stereo signal is recorded on the right channel track, and There is an audio multiplex recording tape in which a performance signal is recorded on one side, and a model singer's singing signal is recorded on the other side. There are two ways to use the audio multiplex bell tape: one uses only the performance signal, and the other uses both the performance signal and the singing signal. In addition, with current audio multiplex recording tapes, it is not determined whether the performance signal is recorded on the left or right channel track, so when using the audio multiplex recording tape, the performance signal is recorded using the audio multiplex volume. It was necessary to select the recorded track.

In Figure 1, (1) is a first magnetic head that reproduces a signal recorded on a left channel track of a magnetic tape;
2) is a second magnetic head for reproducing the signal recorded on the right channel track, and (3) is the first magnetic head (1).
), (4) a second preamplifier that amplifies the output signal of the second magnetic head (2), (5) an audio multiplex volume, (6) a volume polynym, (7) ) is the main amplifier, and (8) is the speaker. When the grounded movable contact (5a) of the audio multiplex polyneme (5) is at the midpoint position shown, the first and second
The output signals of preamplifiers (3) and (4) are mixed at equal levels at point A, and the mixed signal is
) and a main amplifier (7) to a speaker (8), and a sound corresponding to the mixed signal is emitted from the speaker (8). Furthermore, when the movable contact (5a) of the audio multiplexing volume (5) is moved to the point B side, the output signal of the first preamplifier (3) is attenuated, and only the output signal of the second preamplifier (4) is moved to point A. A sound corresponding to the output signal of the second preamplifier (4) is emitted from the speaker (8). Furthermore, a movable contact (5a) of the audio multiplex volume (5)
When moved to the point C side, the output signal of the second preamplifier (4) is attenuated, and only the output signal of the first preamplifier (3) is obtained at point A, and the output signal of the first preamplifier (3) is obtained from the speaker (8). ) is emitted according to the output signal.

When reproducing a stereo recording tape using the magnetic tape reproducing apparatus shown in FIG. 1, the movable contact (5a) of the audio multiplex volume (5) may be set at the midpoint position. Then, the left stereo signal from the first preamplifier (3) and the second
The right stereo signal from the preamplifier (4) is mixed at the same level and obtained at point A, and a sound corresponding to the mixed signal of the left and right stereo signals is emitted from the speaker (8). Next, if you want to simultaneously reproduce the performance signal and singing signal of the audio multiplex recording tape in which the performance signal is recorded on the left channel track and the singing signal is recorded on the right channel track, the movable contact of the audio multiplex volume (5) ( 5a) to the midpoint position, and if only the performance signal is to be reproduced, the movable contact (5a) may be moved to the point C side. Furthermore, when it is desired to simultaneously reproduce the performance signal and singing signal of the audio multiplex recording tape in which the singing signal is recorded on the left channel track and the performance signal is recorded on the right channel track, the movable contact (5a) of the audio multiplex volume (5) is used. ) to the middle position, or if you wish to reproduce only the performance signal, move the movable contact (5
What is necessary is to move a) to the point B side.

On the other hand, a stereo type magnetic tape reproducing apparatus is disclosed in, for example, Japanese Utility Model Application Publication No. 155619/1983, but FIG. 2 shows an improved version of the same to be more suitable for a karaoke apparatus. In FIG. 2, the output signal of the first preamplifier (9) is the first volume volume a1 and the first main amplifier a1.
The output signal of the second preamplifier (131) is applied to the first speaker az via the second volume volume I and the second main amplifier (151).
is applied to. In addition, the first and second main amplifiers a
The collector-emitter path of a transistor η used as an audio multiplex switch is connected between the input terminals of υ and a9, and the base of the transistor fin is connected to a DC power source al via a manual switch. In order to reproduce a stereo recording tape using the apparatus shown in FIG. 2, it is sufficient to set the movable contact (20a) of the audio multiplex volume (2) to the middle position and turn off the manual switch a8. Then, the left stereo signal reproduced by the first magnetic head (all) becomes
The right stereo signal applied to the first speaker via the first preamplifier (9), the first volume volume (II) and the first main amplifier aυ, and reproduced by the second magnetic head 4 is applied to the second preamplifier 0, the second Since it is applied to the second speaker ae via the volume polyneem I and the second main amplifier Q51, stereo sound with good separation can be obtained from the first and second stereophonic forces az and αe. When using an audio multiplex recording tape i on which the performance signal is recorded on the track and the singing signal on the right channel track, and only the performance signal is to be played back, connect the movable contact (20a) of the audio multiplex volume ■ to point C. At the same time, turn on the manual switch and turn on the transistor (17). Then, the second magnetic head (23
The singing signal is reproduced by the second preamplifier (9), the singing signal amplified by the second preamplifier (131) is attenuated, and the performance signal reproduced by the first magnetic head (2υ) is sent to the first preamplifier (9) and the first volume volume 1n.
(1 and the first main amplifier (1N) to the first speaker (12+), and the output signal of the first volume volume (11) is applied to the second speaker (α0) via the transistor fin and the second main amplifier (α9). is applied to the first
Only the sound corresponding to the performance signal is emitted at the same level from the second speakers α2 and (161).Sound multiplexing in which the singing signal is recorded on the left channel track and the performance signal is recorded on the right channel track. Similarly, when reproducing only the performance signal of the recording tape, the audio multiplex voice IJ,
- If you move the movable contact (20a) of the wire to the point B side and turn on the manual switch, only the sound corresponding to the performance signal of the same level will be emitted from the first and second speakers (121 and scream). be done.

As mentioned above, in the magnetic tape playback apparatus shown in FIGS. 1 and 2, if the audio multiplex volume and audio multiplex switch are operated according to the tape being used or the desired playback state,
Appropriate playback can be performed. However, it is extremely troublesome to perform the above operation every time a magnetic tape is loaded into a playback device, and if the operation is performed incorrectly, undesirable playback sound may be generated and the beginning of the song may have to be re-recorded. However, the playback device was not easy to use.

(c) Purpose of the Invention The present invention has been made in view of the above-mentioned points. It is something to do.

B) Structure of the Invention The magnetic tape reproducing apparatus according to the present invention comprises: a first magnetic head for reproducing a left channel signal of a magnetic tape; a second magnetic head for reproducing a right channel signal of the magnetic tape;
first and second signal paths through which the output signals of the first and second magnetic heads pass, respectively; and the first and second @ paths?
The first and second signal cutoff circuits arranged in each of the first and second signal paths detect the presence of a signal in only one of the first and second signal paths, and use the output signal to detect the presence of a signal in only one of the first and second signal paths. and a detection circuit that drives a signal cutoff circuit placed in the signal path.

(E) Embodiment FIG. 3 is a circuit block diagram showing an embodiment of the present invention.
(C) is a first magnetic head that plays back the left channel signal recorded on the left channel track of the magnetic tape, and (C) is the second magnetic head that plays back the right channel signal recorded on the right channel track. C) is a first preamplifier that amplifies the output signal of the first magnetic head (C);
C) is a second preamplifier that amplifies the output signal of the second magnetic head, (5) is a first signal cutoff circuit connected to the output terminal of the first preamplifier (C), and (C) is the ,
A second signal cutoff circuit connected to the output terminal of the second preamplifier (C); (C) a first waveform shaping circuit that shapes the waveform of the output signal of the first preamplifier (C); A second waveform shaping circuit that shapes the waveform of the output signal of the bully amplifier (A), and a second waveform shaping circuit (C31) that cuts off the first and second signals according to the output signals of the first and second waveform shaping circuits (1) and (2). This is a detection circuit that drives circuits (2) and (3).

Generally, the left stereo signal is placed on the left channel track.
On a stereo recording tape in which the right stereo signal is recorded on the right channel track, the beginnings of the songs are aligned. On the other hand, in an audio multiplex recording tape in which the performance signal is recorded on one track and the singing signal on the other track, since there is a prelude to the song, the beginning of the singing signal is different from the beginning of the performance signal. There is a delay of several tens of seconds. The present invention focuses on this point, and if the beginnings of the songs are aligned, it is considered to be a stereo tape, and if the beginnings of the songs are not aligned, it is considered to be an audio multiplexed tape, and the tape is first recorded. It is assumed that a performance signal is present in the signal path from which reproduction No. 1 is obtained, and the state of the circuit is automatically changed.

Now, if a stereo recording tape is being played back, the output signal of the first preamplifier (c) and the output signal of the second preamplifier (to) are generated almost simultaneously, and the first and second waveform shaping circuits and ( The output signals of (to) become rHJ almost simultaneously.

Therefore, the detection circuit C11) has the first input terminal (31a)
is "L", the second input terminal (31b) is rHJ, the first output terminal (31c) is "H", the second output terminal (31d) is rL
In order to generate a J signal, the first input terminal (31a) is set to "H", the second input terminal (31b) is set to rLJ, the first output terminal (31c) is set to "L", and the second output terminal (31c) is set to "L". 31d) rHJ
The first and second input terminals (31
Both a) and (31b) are configured to cut rHJ and generate rLJ signals at the first and second output terminals (31c) and (31d).

Therefore, for stereo tape playback, when the outputs of the first and second waveform shaping circuits w1@ and the ring are both rHJ, the outputs of the detection circuit 61) are both rLJ, and the first and second signal cutoff circuit surfaces and (to) do not operate, the left stereo signal is sent to the first output terminal G, and the left stereo signal is sent to the second output terminal (
In 2), a right stereo signal is generated and stereo reproduction is achieved.

Next, if we are playing an audio multiplex recording tape in which the performance signal is recorded on the left channel track and the singing signal is recorded on the right channel track, the output signal of the first preamplifier (C) is generated first. , the output signal of the first waveform shaping circuit (2) becomes "H" first. Therefore, the first input terminal (31a) of the detection circuit C1υ becomes rHJ, the second input terminal (31b) becomes rLJ, and the first output terminal (31
6) becomes "L" and the second output terminal (31d) becomes rHJ.

Therefore, the second signal cutoff circuit (2
) is activated and cuts off the singing signal which is the output signal of the second preamplifier (to). As a result, only the performance signal, which is the output signal of the first preamplifier (c), is transmitted to the subsequent stage and is emitted from a speaker (not shown).

Furthermore, if we are playing back an audio multiplex recording tape in which the singing signal is recorded on the left channel track and En-4a is recorded on the right channel track, the output signal of the second preamplifier (C) is generated first. , the output signal of the second waveform shaping circuit becomes rHJ first. Therefore, the first input terminal (31a) of the detection circuit 11 is rLJ, and the second output terminal 31b) is rH.
J, and the first output terminal (31c) of the detection circuit 01)
is "H", and the second output terminal (31d) is rLJ. Therefore, the first signal cutoff circuit (c) to which the rHJ signal is applied is activated and cuts off the singing signal that is the output signal of the first preamplifier (c). As a result, only the performance signal, which is the output signal of the second preamplifier (4), is transmitted to the subsequent stage and emitted from the speaker.

Therefore, if the configuration is as shown in FIG. 3, appropriate reproduction according to the type of magnetic tape can be performed simply by loading the magnetic tape into the reproduction device.

Figure 4 shows an example of the concrete circuit shown in Figure 3.
(c) is an exclusive OR circuit connected to the output terminals of the first and second waveform shaping circuits (b); (c) is a first transistor to which the output signal of the exclusive OR circuit (b) is applied to the base; (to)
is a first flip-flop four-tube circuit that operates according to the on/off state of the first transistor, 0? ) and (to) are the second and third transistors driven by the ζ output of the first flip-flop circuit (to), and 09 has the input terminals the outputs of the first and second waveform shaping circuits (to), respectively. @2 flip-flop circuits connected to the terminals, 顛 and (41), respectively control the input terminals of the second flip-flop circuit according to the ζ output of the first flip-flop circuit (to); a fifth transistor (4 is the second transistor);
A first cutoff transistor is turned on in response to the ζ output of the flip-flop circuit c19, and a second cutoff transistor is turned on in response to the output of the second flip-flop circuit 0I.

In addition, (A4tt'-1, monostable multivibrator, (
C) is a sixth transistor that operates according to the output signal of the monostable multivibrator (441), and the monostable multivibrator 04 and the sixth transistor 0!9 are arranged to prevent malfunction.

Next, the operation will be explained. When a stereo recording tape is played back, left and right stereo signals are generated almost simultaneously at the output terminals of the first and second preamplifiers (to), and are shaped by the first and second waveform shaping circuits (2) and (7). and is applied to the exclusive OR circuit (good). Since the input of the exclusive OR circuit changes from rLJ to rHJ at the same time, the output is r
LJ remains unchanged, and the first transistor (to) remains off. Furthermore, the monostable multivibrator (incorporated) is not triggered, and the 6th) transistor (c) also remains in the off state. Since the first flip-flop circuit (2) has the truth values shown in Table 1, when the first transistor (2) is off, the ζ output is rLJ and the output is rHJ. Since the output of the first flip-flop circuit (to) is applied to the bases of the second and third transistors 0η and (to), the output of the first flip-flop circuit is as follows. Transistor (b) and cIa are on. Therefore, regardless of the state of the output of the second flip-flop, the first
The bases of the second cut-off transistors (6) and (43) are grounded, and the first and second cut-off transistors Q4 and (c) are turned off. Therefore, the left voltage obtained at the output terminal of the first preamplifier (c) The stereo signal is generated as it is at the first output terminal 03, and the right stereo signal obtained at the output terminal of the second preamplifier (E) is generated as it is at the second output terminal (to) and is transmitted to the subsequent stage.

Next, when playing back the audio multiplex recording tape with the performance signal recorded on the left channel track and the singing signal recorded on the right channel track, a performance signal corresponding to the accompaniment is first generated at the output end of the first preamplifier (C). Then, it is applied to the input terminal of the exclusive OR circuit (2) via the first waveform shaping circuit (to), and an output signal of rHJ is generated at the output terminal of the exclusive OR circuit (2). The output signal "H" triggers the monostable multivibrator (44), so its output terminal becomes rHJ and the sixth transistor Is is turned on. Therefore, even if the output terminal of the exclusive OR circuit becomes rHJ, the first transistor will not turn on. As time passes, the monostable multivibrator reverses according to its own time constant, and the base of the sixth transistor (c) becomes r.
When LJ is reached, the sixth transistor (c) is turned off, the output signal rHJ of the exclusive OR circuit (b) is applied to the base of the first transistor (to), and the first transistor (to) is turned on. . Then, the input of the first flip-flop circuit (to) becomes rLJ, and the π output remains rHJ, so according to Table 1, the ζ output of the first flip-flop circuit (to) becomes rHJ, and the ζ output becomes rHJ. Become rLJ. When the ζ output reaches rLJ, the second and third transistors 07) and 07 are turned off, and the forced output of the second flip-flop circuit CHI is released.

On the other hand, when the output signal rHJ of the first waveform shaping circuit 4 is generated, the R input of the second flip-flop circuit 6 becomes rHJ,
8 input becomes "L", and the ζ output becomes rLJ and the ζ output becomes rHJ according to the truth values in Table 2. Then, after the elapse of a time determined according to the time constant of the monostable multivibrator θ4, the second and third transistors C (η and (to) are turned off).

The ζ output rHJ of the 27th lip-prop circuit (to) is the second
! ! is applied to the base of the cut-off transistor G43, turning on the second cut-off transistor and turning on the second preamplifier (to).
The singing signal obtained at the output end of is cut off.

17th. At the same time that the output of the flip-flop circuit becomes rLJ, the ζ output becomes rHJ, and the fourth and fifth transistors 01 and 4 are turned on. Then.

The R input and S input of the 27th flip-flop circuit (to) are both rLJ, and based on Table 2, the output from the second flip-flop circuit (to) is maintained at rHJ. Cutting off the input of the second flip-flop circuit C1l by the fourth and fifth transistors and (4υ)
This is to prevent malfunctions during silent parts between songs.

Furthermore, when playing an audio multiplex recording tape in which a singing signal is recorded on the left channel track and a performance signal is recorded on the right channel track, the 211th disconnection transistor (6) is turned on by the same operation, and the first preamplifier is turned on. The singing signal obtained at the fourth output end is cut off.

The monostable multivibrator and the 6th transistor (4) are arranged to prevent malfunction. In other words, when playing back a stereo recording tape, an exclusive OR circuit (
When both power outputs (of the product) are simultaneously switched from rLJ to rHJ, the output of the exclusive OR circuit (2) must maintain the state of rLJ, but depending on the recording conditions etc., even if it is a stereo recording tape, The start time of the first part may be slightly different, and in such a case, if the monostable multivibrator 04) and the sixth transistor (45) are not present, the rHJ output of the exclusive OR circuit will cause the first Transistor 05) turns on, and the first flip-flop circuit (
) is triggered, and the first and second m-off transistors 02
and G13 may turn on. However, the output r of the monostable multivibrator (equipped with four transistors and a sixth transistor Q (g), exclusive OR circuit)
Only when HJ continues for more than a predetermined time, that is, the outputs of the first and second waveform shaping circuits (c) and the equipment become different values (one is "H" and the other is "L") after a predetermined time. If the first transistor 0ω is turned on only when a stereo recording tape is played back, a malfunction in which one channel signal is cut off can be reliably prevented.

In that case, the time constant of the monostable multivibrator (4~) should be set to an appropriate value of about 10 seconds, since the error in stereo recording is about a few seconds, and the prelude time for audio multiplex recording is more than a few tens of seconds. .

(f) Effects of the Invention As described above, the present invention has the advantage that it is possible to automatically select between a stereo recording tape and an audio multiplex recording tape. Further, according to the present invention, since the playback circuit can be automatically switched according to the selection, there is an advantage that a playback circuit can be provided depending on the type of recording. In particular, in the present invention, the conventionally essential audio multiplex volume can be omitted or disconnected from the reproduction circuit, so that singing can be automatically enjoyed in the optimal condition.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional monaural magnetic tape playback device, FIG. 2 is a circuit diagram showing a conventional stereo magnetic tape playback device, and FIG. 3 is a circuit diagram showing an embodiment of the present invention. 4 and 4 are circuit diagrams showing specific circuit examples thereof. Explanation of main drawing numbers 4... Preamplifier @ (to)... Signal cutoff circuit,
@■...Waveform shaping circuit, C11)...Detection circuit. Applicant: Sanyo Electric Co., Ltd. and 1 other agent: Shizuo Sano, patent attorney Figure 1 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) The first unit that reproduces the left channel signal of the magnetic tape.
a second magnetic head for reproducing the right channel signal of the magnetic tape; a first signal path for passing the output signal of the first magnetic head; and a second signal path for passing the output signal of the second magnetic head. a signal path, first and second signal cutoff circuits disposed on each of the first and second signal paths, and a detection circuit that detects the presence of a signal only on one of the first and second signal paths. A magnetic tape playback device comprising: a signal cutoff circuit arranged in a signal path on the side where the signal does not exist, driven by the output signal of the detection circuit.