JPH075523Y2 - Tape pre-coder miuteing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a tape recorder in which first and second tape recorders having at least a reproducing function are incorporated in the same cabinet, and particularly to a muting circuit. Pertain to.

(B) Conventional Technology Recently, a tape recorder called a so-called double tape recorder in which two tape recorders are incorporated in the same cabinet has become widespread, and as a technology related to a reproducing circuit of such a tape recorder, for example, Kosho
There is one disclosed in Japanese Patent Publication No. 57-47494. The double tape recorder includes a first reproducing amplifier circuit for amplifying the signal reproduced by the first magnetic head incorporated in the first tape recorder as disclosed in the above publication. A second reproducing amplifier circuit for applying a signal reproduced by a second magnetic head incorporated in the second tape recorder and amplifying the signal.
It is equipped with two reproducing amplifier circuits, and in such a configuration, the first
The signal reproduced by the tape recorder and the signal reproduced by the second tape recorder can be mixed and heard. However, such a reproduction signal mixing function is rarely used in practice, and it is general that one tape recorder performs a reproduction operation. When one of the two tape recorders is used to listen to the reproduced sound, it is useless to provide two reproducing amplifier circuits. As a technique for improving such a point, recently, a signal reproduced by the first magnetic head and a signal reproduced by the second magnetic head are selectively input to one reproducing amplifier circuit by the function of the switch circuit. In particular, there has been developed one in which such a switch circuit and a reproducing amplifier circuit are incorporated in one IC (integrated circuit).

(C) Problems to be solved by the invention A tape recorder configured to select and input a signal reproduced by the first magnetic head and the second magnetic head to one reproducing amplifier circuit by the action of the switch circuit. Then, when both the first tape recorder and the second tape recorder are set to the reproduction operation state, the reproduction operation of one tape recorder is preferentially performed. Therefore, when the two tape recorders, the first tape recorder and the second tape recorder, are in the reproducing operation state and the tape recorder whose reproduction operation is prioritized is stopped, the switching operation of the switch circuit is performed and the other one is stopped. The signal reproduced by the magnetic head of the tape recorder of will be input to the reproduction amplifier circuit,
There is a problem that a noise signal is generated when this switching operation is performed. The present invention is intended to provide a muting circuit that is improved in this respect.

(D) Means for Solving the Problems The muting circuit of the present invention is incorporated in the first tape recorder and performs reproduction operation, and the first magnetic head is incorporated in the second tape recorder and reproduction is performed. A second magnetic head that operates, a reproduction amplifier circuit that receives a signal reproduced by the first magnetic head or the second magnetic head, and amplifies the signal, and an input signal path of the reproduction amplifier circuit. It is provided and guides a reproduction signal from the first magnetic head or the second magnetic head to the reproduction amplifier circuit according to the reproduction operation of the first tape recorder and the second tape recorder, and the first tape recorder and the second tape recorder. First when both tape recorders are in playback status
A switch circuit that gives priority to the reproduction signal from the magnetic head to the reproduction amplifier circuit, and is provided between the signal transmission path through which the signal amplified by the reproduction amplifier circuit flows and the ground, and is in an operating state. The muting circuit for shunting the signal flowing through the signal transmission path and the switch circuit for guiding the reproduction signal from the first magnetic head to the reproduction amplifier circuit when the reproduction operation of the first tape recorder is performed. It is composed of a control circuit which outputs a switching signal and outputs a drive signal for driving a display element which indicates that the reproducing operation of the first tape recorder is being performed.

(E) Action The present invention suppresses the noise signal generated during the switching operation of the switch circuit, which selectively guides the signal reproduced by the first magnetic head or the second magnetic head to the reproducing amplifier circuit, by the muting circuit. It was done.

(F) Embodiment The illustrated circuit is an embodiment of the muting circuit of the present invention. In the figure, (1) is a first magnetic head which is incorporated in a first tape recorder and which reproduces a signal recorded on a magnetic tape mounted in the tape recorder, and (2) is incorporated in a second tape recorder. A second magnetic head for reproducing a signal recorded on a magnetic tape which is mounted on the tape recorder, and (3)
Is an IC tape recorder circuit, which is provided with input terminals (4) and (5) to which signals reproduced by the first magnetic head (1) and the second magnetic head (2) are applied. . (6) is a reproduction amplifier circuit incorporated in the tape recorder circuit (3), (7) is an output terminal for outputting a reproduction signal amplified by the reproduction amplifier circuit (6), (8) Is an electronic switch (9) incorporated in the tape recorder circuit ( 3 ) and for guiding the reproduction signals from the first magnetic head (1) and the second magnetic head (2) to the reproduction amplification circuit (6). It is a switch circuit that switches the target. The switch circuit (8) has a control terminal (10)
And a first magnetic head (1) when an H (high) level signal is applied to the control terminal (10).
The signal reproduced by is led to the amplifier circuit for reproduction (5),
When a signal of L (low) level is applied to the control terminal (10), the signal reproduced by the second magnetic head (2) is guided to the reproducing amplifier circuit (6). . (11) is a variable resistor for adjusting the level of the reproduction signal output to the output terminal (7) of the tape recorder circuit ( 3 ), and (12) is the level of the variable resistor (11). A line amplifier circuit for applying the adjusted signal and amplifying the signal, (13) is connected to an input terminal of an amplifier having a large output, to which the signal amplified by the line amplifier circuit (12) is applied. Output terminal. (14) is a first reproduction switch that is closed during the reproduction operation of the first tape recorder, (15) is a first stop switch that is closed during the stop operation of the first tape recorder, and (16) is a second switch The second reproduction switch that is closed when the tape recorder is operated for reproduction, (17) is the second stop switch that is closed when the second tape recorder is stopped, and (18)
Is a control circuit that outputs a signal corresponding to each operation to an output terminal when an H-level signal is applied to the input terminal with the closing of each switch. (19) is a first reproduction switching signal which outputs an H level switching signal when the first reproduction switch (14) is closed and is connected to the control terminal (10) of the switch circuit 8). The output terminal (20) outputs the H level signal when it is in the stopped state and outputs the L level signal after a predetermined time when the first reproducing switch (14) is closed. The output signal is an output terminal for the output, and its output signal is inverted from the L level to the H level when the first stop switch (15) is closed in the reproducing state. Reference numeral (21) is a display output terminal for outputting an H level signal as soon as the first reproduction switch (14) is closed. When the first reproduction switch (15) is in the reproduction state, When closed, the H level signal is inverted to the L level after a predetermined time. (22) is a second reproduction switching signal output terminal for outputting an H level switching signal when the second reproduction switch (16) is closed, and (23) is an H level signal when in a stopped state. A second muting output terminal that outputs an L level signal after a predetermined time when the second reproduction switch (16) is closed while being output.
When the second stop switch (17) is closed in the reproducing state, its output signal is inverted from the L level to the H level. (24) is an H level at the first reproduction switching signal output terminal (19) provided in the control circuit (18).
This is a first reproduction switching circuit which is in an operating state while a level signal is being output, and has an action of putting the first tape recorder in a reproducing state. Reference numeral (25) is a second reproduction switching circuit which is in an operating state while an H level signal is being output to the second reproduction switching signal output terminal (22). Have Reference numeral (26) is a light emitting diode whose anode is connected to the display output terminal (21) and whose cathode is grounded through the resistor (27). When the LED is in a lighting state, the reproducing operation of the first tape recorder is performed. Has an effect of displaying that the operation is being performed. (28) is a muting transistor whose collector is connected to the output signal path (29) of the line amplifier circuit (12) and whose emitter is grounded. The output signal path (29) is in a conducting state. It has the effect of diverting the signal flowing through. (30) is a control transistor for controlling the operation of the muting transistor (28), the emitter of which is connected to the power supply and the collector of which is connected to the base of the muting transistor (28) through the resistor (31). It is connected to the. The base (32) is connected to the first muting output terminal (20) provided in the control circuit (18) through the resistor (33) and the collector is connected through the resistor (34). A first transistor (35) connected to the base of the control transistor (30) is a second transistor whose collector is connected to the emitter of the first transistor (32) and whose emitter is grounded. The base is connected to the second muting output terminal (23) of the control circuit (18) through the resistor (36) and the diode (37) and the resistor (3
6) and the diode (38) to the cathode of the light emitting diode (26). The muting circuit of the present invention is constructed as described above. Next, the operation of such a circuit will be described.

Power is supplied to each circuit when the power switch (not shown) is closed, but when in the stopped state, the first reproduction switching signal output terminal (19) and the display output terminal (2) of the control circuit (18)
1) and the second reproduction switching signal output terminal (22) output an L level signal, and the first muting output terminal (20) and the second muting output terminal (23) are H level.
The level signal is output. When an H level signal is output to the first muting output terminal (20) and the second muting output terminal (23), the first transistor (32) and the second transistor (35) are output from the output terminal. A bias current is supplied to the base, and the first transistor (32) and the second transistor (35) become conductive. When the first transistor (32) and the second transistor (35) become conductive, the control transistor (30) is biased and becomes conductive, so that the control transistor (30) is connected between the emitter and collector and the resistor (3).
A bias current is supplied to the base of the muting transistor (28) through (1), and the muting transistor (28) becomes conductive. Therefore, the signal flowing through the output signal (29) of the line amplifier circuit (12) is in a state of being bypassed by the muting transistor (28), and a noise signal or the like is not output to the output terminal (13). Absent.

When the reproduction operation of the first tape recorder is performed in the stop state, the first reproduction switch (14) is closed and the switching signal is input to the control circuit (18). When a switching signal is input to the control circuit (18) by closing the first reproducing switch (14), a first reproducing switching signal output terminal (19)
Also, the H level signal is output to the display output terminal (21), and after a predetermined time, the H level signal output to the first muting output terminal (20) is inverted to the L level. When an H-level signal is output to the first reproduction switching signal output terminal (19), the first reproduction switching circuit (24) is brought into the operating state, and the first tape recorder is brought into the reproducing operating state. Also, H is applied to the switching signal output terminal (19) for the first reproduction.
When the level signal is output, the H level signal is applied to the control terminal (10) of the switch circuit (8). Therefore, the switch (9) outputs the reproduction signal from the first magnetic head (1) to the reproduction amplifier circuit. The state is changed to the state (6). When an H-level signal is output to the first reproduction switching signal output terminal (19), the above-described switching operation is performed to configure the reproduction operation state of the first tape recorder. Such a switching operation is performed. Output terminal for the first muting (20)
Since the H-level signal is output to the muting transistor (28) and the muting transistor (28) is held in the conductive state, the noise signal generated by the switching operation is not output to the output terminal (13). Then, after a predetermined time has passed, the first
Since the H level signal output to the muting output terminal (20) is inverted to L level, the first transistor (32) is inverted to the non-conductive state. When the first transistor (32) is turned off, the base bias of the control transistor (30) is cut off, and the control transistor (30) is turned off. Therefore, the muting transistor (28) is turned off. It is made conductive. In this way, the reproduction operation state of the first tape recorder is configured, and the signal recorded on the magnetic tape mounted on the first tape recorder is reproduced by the first magnetic head (1). The reproduction signal reproduced by the first magnetic head (1) is input to the reproduction amplifier circuit (6) through the switch (9), amplified, and then output to the output terminal (7). The reproduction signal output to the output terminal (7) is adjusted in level by the variable resistor (11) and then input to the line amplifier circuit (12). The reproduction signal input to the line amplifier circuit (12) is output to the output terminal (13) without being amplified and then bypassed. Therefore,
The user can hear the signal reproduced by the first tape recorder. Further, when the reproduction operation of the first tape recorder is being performed, since the H level signal is output to the display output terminal (21) of the control circuit (18), the light emitting diode (26) is in a lighting state, The user can recognize that the reproducing operation of the first tape recorder is being performed. When the first tape recorder is stopped and the first tape recorder is stopped, the first stop switch (15) is closed and the control circuit (1
A switching signal for stopping is input to 8). When a stop switching signal is input to the control circuit (18), an H level signal is output to the first muting output terminal (20) and the first reproduction switching signal output terminal (19) is output. The output H level signal is inverted to the L level, and then the H level signal output to the display output terminal (21) is inverted to the L level. When the H-level signal is output to the first muting output terminal (20), the first transistor (32) is biased and becomes conductive, so that the control transistor (30) and the muting transistor are described above. (28) is biased into conduction. When the H level signal output to the first reproduction switching signal output terminal (19) is inverted to L level, the first reproduction switching circuit (24) returns to the inoperative state and the first tape recorder is stopped. Is switched to. At this time, since the L level signal is applied to the control terminal (10) of the switch circuit (8), the switch circuit (8)
However, the noise signal is not output to the output terminal (13) because the muting transistor (28) is conductive. After such an operation is performed, the output signal of the display output terminal (21) is changed from the H level to the L level.
It is inverted to the level and the light emitting diode (26) is turned off.

Although the reproduction operation and the stop operation of the first tape recorder are performed as described above, the reproduction operation of the second tape recorder will be described below. When the reproduction operation of the second tape recorder is performed while the first tape recorder and the second tape recorder are stopped, the second reproduction switch (16) is closed and the switching signal is input to the control circuit (18). When a switching signal is input to the control circuit (18) by closing the second reproducing switch (10), an H level signal is output to the second reproducing switching signal output terminal (22) and after a predetermined time. The H level signal output to the second muting output terminal (23) is inverted to the L level. When an H-level signal is output to the second reproduction switching signal output terminal (22), the second reproduction switching circuit (25) is brought into the operating state, and the second tape recorder is brought into the reproducing operating state. Further, when in such a state, the control terminal (10) of the switch circuit (8)
Since the L level signal is applied to the switch, the switch (9) is in a state of guiding the reproduction signal from the second magnetic head (2) to the reproduction amplification circuit (6). In this way, the playback operation status of the second tape recorder is configured.
While the switching operation is being performed, the H-level signal is output to the second muting output terminal (23) and the muting transistor (28) is held in the conductive state, so that the switching operation is accompanied. The generated noise signal is not output to the output terminal (13). Then, after a lapse of a predetermined time, the H-level signal output to the second muting output terminal (23) is inverted to L-level, so that the second transistor (35) is inverted to the non-conductive state. When the second transistor (35) is turned off, the base bias of the control transistor (30) is cut off, and the control transistor (30) is turned off. Therefore, the muting transistor (28) is turned off. It is made conductive. In this way, the reproducing operation state of the second tape recorder is configured, and the signal recorded on the magnetic tape mounted on the second tape recorder is the second signal.
Reproduced by the magnetic head (2). Since the signal reproduced by the second magnetic head (2) is input to the reproducing amplifier circuit (6) through the switch (9) and amplified, the reproduced signal is, as described above, the line amplifier circuit (12).
Is further amplified by and then output to the output terminal (13).
Therefore, the user can listen to the signal reproduced by the second tape recorder. When the second tape recorder is stopped and the second tape recorder is stopped, the second stop switch (17) is closed and a switching signal for stopping is input to the control circuit (18).
When a stop switching signal is input to the control circuit (18), an H level signal is output to the second muting output terminal (23) and the second reproducing switching signal output terminal (22) is output. The output H-level signal is inverted to L-level. H at the second muting output terminal (23)
When the level signal is output, the second transistor (35)
Is biased into the conductive state, the control transistor (30) and the muting transistor (28) are biased into the conductive state as described above. When the H level signal output to the second reproduction switching signal output terminal (22) is inverted to L level, the second reproduction switching circuit (25) returns to the inoperative state and the second tape recorder is stopped. Is switched to. When the switching operation is performed, the muting transistor (2
Since 8) is conductive, no noise signal is output to the output terminal (13).

The operation when only one of the first tape recorder and the second tape recorder is operated is performed as described above. Next, the case where the reproducing operations of the two tape recorders are performed simultaneously will be described. First, the case where the reproduction operation of the second tape recorder is performed while the first tape recorder is in the reproduction operation state will be described. When the first tape recorder is in the reproduction operation state, the first reproduction switching signal output terminal (1
The signal of H level is output to 9), and the signal reproduced by the first magnetic head (1) is input to the reproducing amplifier circuit (6). When the reproduction operation of the second tape recorder is performed in such a state, an H level signal is output to the second reproduction switching signal output terminal (22) of the control circuit (18) and the second muting output terminal is output. The H level signal output to (23) is inverted to the L level after a predetermined time. When an H-level signal is output to the second reproduction switching signal output terminal (22), the second reproduction switching circuit (25) is brought into the operating state as described above, and the second tape recorder is put into the reproducing operating state. . However, since the reproduction signal from the first magnetic head (1) is input to the reproduction amplifier circuit (6) by the operation of the switch circuit (8), the reproduction signal of the first tape recorder is output to the output terminal (13). Therefore, the reproduction signal of the second tape recorder is not heard. Since the switching operation of the switch circuit (8) is not performed when such an operation is performed, a noise signal is not generated. When the second tape recorder is stopped in such a state, the H level signal output to the second reproduction switching signal output terminal (22) of the control circuit (18) is inverted to the L level and 2 H for the muting output terminal (23)
The level signal is output. When the output signal from the second reproduction switching signal output terminal (22) becomes L level, the second reproduction switching circuit (25) becomes inoperative and the second tape recorder is stopped. In this way, even if the reproduction operation and the stop operation of the second tape recorder are performed while the first tape recorder is in the reproduction operation state, there is no effect on the reproduction operation of the first tape recorder.

As described above, when the reproduction operation and the stop operation of the second tape recorder are performed while the first tape recorder is in the reproduction state, the operation is performed. The operation when the reproduction operation and the stop operation of the 1 tape recorder are performed will be described. When the first tape recorder is in the stopped state and the second tape recorder is in the playback operation state, the first
Playback switching signal output terminal (19), display output terminal (21)
And an L level signal is output to the second muting output terminal (23), and the first muting output terminal (20)
And the H level signal is output to the second reproduction switching signal output terminal (22). When the reproduction operation of the first tape recorder is performed in such a state, an H-level signal is output to the first reproduction switching signal output terminal (19) and the display output terminal (21), and after a predetermined time, the first signal is output. The H level signal output to the muting output terminal (20) is inverted to the L level. When the H level signal of the display output terminal (21) is output, the light emitting diode (26),
A bias current flows to the base of the second transistor (35) through the diode (38) and the resistor (36), and the second transistor (35) is turned on. When the second transistor (35) becomes conductive, the base of the first transistor (32) is biased for a predetermined time, so that the control transistor (30) and the muting transistor (28) are biased and conductive during the period. become. Further, when an H level signal is output to the first reproduction switching signal output terminal (19), the first reproduction switching circuit (24) enters the operating state and the switching operation by the switch circuit (8) as described above. And the signal reproduced by the first magnetic head (1) is reproduced by the reproducing amplifier circuit (6).
It will be input to. As a result of such switching operation, the reproduction signal from the first tape recorder is output to the output terminal (13) instead of the reproduction signal from the second tape recorder, and the reproduction of the first tape recorder is performed. You will hear the motion signal. Since the muting transistor (28) is in a conducting state when the switching operation of the switch circuit (8) is performed, a noise signal associated with the switching is not output to the output terminal (13). When the reproduction operation of the first tape recorder is performed while the second tape recorder is in the reproduction operation state, the operation is performed as described above. When the reproduction operation state is next, the stop operation of the first tape recorder is performed. The operation in the case of performing will be described. When the first tape recorder is stopped, the H-level signal is output to the first muting output terminal (20) and the H-level signal output to the first reproduction switching signal output terminal (19). It is inverted to L level, and then the H level signal output to the display output terminal (21) is inverted to L level. The first
When the H-level signal is output to the muting output terminal (20), the first transistor (32) is biased, so that the first transistor (32) and the second transistor (35) become conductive and control is performed. Transistor (30)
Also, the muting transistor (28) is made conductive. The first reproduction switching signal output terminal (1
When the H level signal output to 9) is inverted to L level, the first reproduction recorder circuit (24) is returned to the inoperative state to switch the first tape recorder to the stopped state and the switch circuit (8). The switching operation of the switch (9) is performed so that the signal reproduced by the second magnetic head (2) is input to the reproducing amplifier circuit (6). When the switching operation is performed, the muting transistor (28) is in the conductive state, so that the noise signal associated with the switching is not output to the output terminal (13). After such an operation is performed, the H-level signal output to the display output terminal (21) becomes L-level, so that the second transistor (35) is reversed to the non-conducting state and the muting is performed. The transistor (28) becomes non-conductive. Therefore, the signal reproduced by the second magnetic head (2), that is, the reproduction signal of the second tape recorder is output to the output terminal (13), and the reproduction signal of the second tape recorder is heard.

Although the muting circuit is provided on the output side of the line amplifier circuit (12) in this embodiment, it may be provided on the input side. Further, although the muting circuit is configured by the muting transistor (28), the control transistor (30), the first transistor (32) and the second transistor (35), other circuit configurations can be used.

(G) Effect of the Invention The present invention provides a tape recorder in which the first tape recorder and the second tape recorder are incorporated.
When the tape recorder is in the replay operation state, when the first tape recorder is in the replay operation state and when both tape recorders are in the replay operation state When the first tape recorder is switched from the replay operation state to the stopped state ,
Since the muting circuit suppresses the noise signal generated during the switching operation of the switch circuit for selectively guiding the signal reproduced by the first magnetic head and the second magnetic head to the reproducing amplifier circuit, the amplifier having a large output It is very effective when applied to a double tape recorder called a tape deck that is used by being connected to.

The present invention provides a muting circuit in which the second tape recorder is in the reproducing operation state by a drive signal for driving a display element provided to indicate that the first tape recorder is in the reproducing operation state. Since the muting operation is controlled by using a signal for a display operation that is not related to the muting operation, the muting operation in the double tape recorder is simple. The practical value of the present invention is very high.

[Brief description of drawings]

The circuit shown is an example of the muting circuit of the present invention. Description of main drawing numbers (1) …… First magnetic head, (2) …… Second magnetic head, ( 3 ) …… Tape recorder circuit, (6) …… Reproduction amplifier circuit, (8) …… Switch circuit, (10) ... control terminal, (12) ... line amplifier circuit, (18) ... control circuit, (19) ... first reproduction switching signal output terminal, (20) ...
… First muting output terminal, (21) …… Display output terminal, (22) …… Second playback switching signal output terminal, (2
3) …… Second muting output terminal, (24) …… First regeneration switching circuit, (25) …… Second regeneration switching circuit, (28)
...... Muting transistor, (30) …… Control transistor, (32) …… First transistor, (3
5) …… Second transistor.

Claims (1)

[Scope of utility model registration request] 1. A tape recorder in which first and second tape recorders having at least a reproducing function are incorporated in the same cabinet, and a first magnetic head incorporated in the first tape recorder and performing a reproducing operation. A second magnetic head incorporated in a second tape recorder and performing a reproducing operation; and a reproduction amplifier for inputting a signal reproduced by the first magnetic head or the second magnetic head and amplifying the signal. Circuit and a reproduction signal output from the first magnetic head and the second magnetic head according to a reproduction operation of the first tape recorder and the second tape recorder, which is provided in an input signal path of the reproduction amplifier circuit. When the first tape recorder and the second tape recorder are both in the reproducing state, they are led to the reproducing amplifier circuit, and the first magnetic recorder A switch circuit for giving priority to a reproduction signal output from the reproducing circuit to the reproduction amplifier circuit, and a signal transmission path through which the signal amplified by the reproduction amplifier circuit flows and ground, and in the operating state. At this time, the muting circuit for diverting a signal flowing through the signal transmission path and the switch circuit for guiding the reproduction signal from the first magnetic head to the reproduction amplifier circuit when the reproduction operation of the first tape recorder is performed. And a drive signal for driving a display element indicating that the reproducing operation of the first tape recorder is being performed,
And a control circuit for outputting a signal for bringing the muting circuit into an operating state when the first tape recorder and the second tape recorder are in a stopped state, and the first tape recorder when the second tape recorder is in a reproducing operation state Is output from the control circuit during the switching operation of the switch circuit accompanying the switching from the reproducing operation state of the first tape recorder to the stop state when both tape recorders are in the reproducing operation state. A muting circuit for a tape recorder, characterized in that the muting circuit is put into an operating state even when the second tape recorder is in a reproducing operation state by a drive signal for driving the display element.