JPH0782603B2 - Display circuit for cassette type tape recorder - Google Patents

Description

The present invention relates to a cassette type tape recorder in which a first tape recorder and a second tape recorder are incorporated in the same cabinet, and more particularly to a display circuit. .

(B) Prior Art Recently, a so-called double cassette tape recorder, in which a first tape recorder having a reproducing function and a second tape recorder having a recording / reproducing function are incorporated in the same cabinet, has become widespread. . There are three types of magnetic tapes that are widely used: normal tape, chrome tape, metal tape, etc.
There are types. Since the respective magnetic tapes have different characteristics, it is necessary to switch the reproduction equalizer, the recording equalizer, and the recording bias current in accordance with the characteristics of the magnetic tape, and the cassette type tape recorder is generally equipped with such a switching mechanism. In addition, recently spread chrome tapes and metal tapes have recesses formed on the rear end surface of the cassette in order to automatically detect the type of each tape. A device for switching the equalizer by detecting such recesses. For example, there is one disclosed in Japanese Utility Model Publication No. 54-18889. The tape recorder configured as described above includes a display device that displays the type of magnetic tape used by turning on a light emitting element such as a light emitting diode. As such a technique, for example, Japanese Utility Model Publication 59-9398. There is one disclosed in the publication.

(C) Problems to be solved by the invention In the tape recorder incorporating the above-mentioned switching device,
It is suitable for double-cassette tape recorders, because the number of operation switches on the panel surface can be reduced because there is no need for operation switches that switch the equalizer according to the type of magnetic tape. On the other hand, when the above-mentioned display device is incorporated in such a double tape recorder, if each tape recorder is provided with a light emitting element for displaying, there is a problem that the configuration becomes complicated and the cost becomes high. The present invention is intended to provide a display circuit that has improved such points.

(D) Means for Solving the Problems The display circuit of the present invention is incorporated in a first tape recorder and has first and second switches for detecting the first magnetic tape and the second magnetic tape, and the first and second switches. 1 Built-in tape recorder and detecting the presence of cassette 1
A detection switch, third and fourth switches incorporated in the second tape recorder and detecting the first magnetic tape and the second magnetic tape, and incorporated in the second tape recorder and detecting the presence / absence of a cassette Second detection switch, first magnetic tape, second magnetic tape and third
It is composed of first, second and third light emitting diodes which indicate by the lighting that the magnetic tape is used.

(E) Operation In the present invention, the first, second and third light emitting diodes are provided to indicate by lighting that the first magnetic tape, the second magnetic tape and the third magnetic tape are used. When the cassette tape is mounted on only one tape recorder, the first, second, and third light emitting diodes are used for the first tape recorder.
Indicates the type of magnetic tape loaded in the tape recorder, and when the second tape recorder is loaded with the cassette tape, the magnetic tape loaded in the second tape recorder by the first, second and third light emitting diodes. The type of is displayed.

(F) Example The illustrated circuit is an example of the display circuit of the present invention.
(1) is a first switch which is incorporated in a first tape recorder having a reproducing function and which is in a closed state when a metal tape is attached, and is a grounded first switch
It has a terminal (1a) and a second terminal (1b). (2) is a second switch which is incorporated in the first tape recorder and is in a closed state when the metal tape and the chrome tape are attached, and the first terminal (2a) and the second terminal which are grounded It has (2b). (3) is a third switch which is incorporated in a second tape recorder having a recording and reproducing function and which is in a closed state when a metal tape is attached, and which has a grounded first terminal (3a) and It has a second terminal (3b). (4) is the second
First terminal (4a), which is the fourth switch that is in the closed state when it is installed in the tape recorder and the metal tape and the chrome tape are installed, and which is grounded.
And a second terminal (4b). (5) is a first detection switch which is built in the first tape recorder and is closed when a cassette tape is mounted, and has a grounded first terminal (5a) and second terminal (5b). I have it. (6) is a second detection switch which is incorporated in the second tape recorder and is closed when a cassette tape is loaded, and has a grounded first terminal (6a) and second terminal (6b). I have it. (7) is a first NOR circuit in which the first and second input terminals are commonly connected and also connected to the power source through the resistor (8), and has a function of inverting the level of the input signal. There is. (9) is a second NOR circuit in which the first input terminal is connected to the output terminal of the first NOR circuit (7) and the second input terminal is connected to the power source through the resistor (10), (11) The first input terminal is the second N
A third NOR circuit, which is connected to the output terminal of the OR circuit (9) and whose second input terminal is connected to the output terminal of the first NOR circuit (7), and (12) is the first and second input terminals. Are commonly connected and are also connected to a power source through a resistor (13), and the second terminal (6) of the second detection switch (6) is connected.
It is a fourth NOR circuit connected to b) and has the function of inverting the level of the input signal. (14) is a first switching transistor whose emitter is connected to the second terminal (1b) of the first switch (1) and whose collector is connected to the input terminal of the first NOR circuit (7), The base is connected to the second terminal (6b) of the second detection switch (6) via the resistor (15). (16)
The emitter is the second terminal (2b) of the second switch (2)
A second switching transistor having a collector connected to the second input terminal of the second NOR circuit (9) and a base connected to the second detection switch (6) via a resistor (17). Is connected to the second terminal (6b) of the. (18) is a third switching transistor whose emitter is connected to the second terminal (3b) of the third switch (3) and whose collector is connected to the input terminal of the first NOR circuit (7), The base is connected to the output terminal of the fourth NOR circuit (12) via the resistor (19). (20) is a fourth switching transistor whose emitter is connected to the second terminal (4b) of the fourth switch (4) and whose collector is connected to the second input terminal of the second NOR circuit (9). And its base is connected to the output terminal of the fourth NOR circuit (12) through the resistor (21). (22), (23) and (24) are first, second and third light emitting diodes which indicate that they are a metal tape, a chrome tape and a normal tape when they are lit, and (25) has a collector which is the first. A first driving transistor connected to a power source via a light emitting diode (22) and a resistor (26) and having an emitter connected to a second terminal (5b) of the first detection switch (5), The base is connected to the output terminal of the first NOR circuit (7) via the resistor (27). (28) is a second driving transistor whose collector is connected to the power source through the second light emitting diode (23) and resistor (29) and whose emitter is grounded, and whose base is the resistor (30). It is connected to the output terminal of the second NOR circuit (9) through. (31) is a third driving transistor whose collector is connected to the power source through the third light emitting diode (24) and resistor (32) and whose emitter is grounded, and whose base is the resistor (33). Through the third NOR
It is connected to the output terminal of the circuit (11). (34) is a control transistor whose collector is connected to the emitter of the first drive transistor (25) and whose emitter is grounded, and whose base is the fourth NOR circuit (12) via a resistor (35). Is connected to the output terminal of. The display circuit of the present invention is configured as described above, and its operation will be described below.

In the illustrated state, neither the first tape recorder nor the second tape recorder is loaded with a cassette tape, and both the first detection switch (5) and the second detection switch (6) are open. Further, in such a state, the first switch (1), the second switch (2), the third switch (3) and the fourth switch (4) are in the closed state as shown. In such a state, the bases of the first switching transistor (14) and the second switching transistor (16) have resistors (13), (15) and (17) at their bases.
Since a bias current flows through the first switching transistor (14) and the second switching transistor (16), they are in a conductive state. Therefore, an H (high) level signal is output to the output terminal of the first NOR circuit (7), and an L (low) level signal is output to the output terminals of the second NOR circuit (9) and the third NOR circuit (11). Is output. Also the 4th NOR
Since the H level signal is applied to the input terminal of the circuit (12), the L level signal is output to the output terminal thereof, and the third switching transistor (1
8), the fourth switching transistor (20) and the control transistor (34) are off. Therefore 1st N
Even if the H level signal output to the output terminal of the OR circuit (7) is applied to the base of the first driving transistor (25) through the resistor (27), the emitter of the first driving transistor (25) is not Since it is in the grounded state, the first drive transistor (25) does not reverse to the conductive state. 2nd N
Since the L level signal is output to both the output terminals of the OR circuit (9) and the third NOR circuit (11), the second drive transistor (28) and the third drive transistor (31) are both non-conductive. . When neither the first tape recorder nor the second tape recorder is loaded with a cassette tape, as described above, the first drive transistor (25), the second drive transistor (28), and the third drive transistor (31) are non-conductive. The first light emitting diode (22), the second
The light emitting diode (23) and the third light emitting diode (24) are in a non-lighting state. Therefore, the user can recognize that neither the first tape recorder nor the second tape recorder is loaded with a cassette tape.

No. 1 when the metal tape is attached to the No. 1 tape recorder
The detection switch (5) is switched from the open state to the closed state, but the first switch (1) and the second switch (2) are not switched and are in the closed state. When the first detection switch (5) is closed, the first driving transistor (2
Since the emitter of 5) is grounded, the first drive transistor (25) is turned on. When the first driving transistor (25) is turned on, a driving current flows through the first light emitting diode (22) connected to the collector as a load, and the first light emitting diode (22) is turned on. Therefore, the user can recognize that the metal tape is attached by turning on the first light emitting diode (22).

The display operation when the metal tape is mounted on the first tape recorder is performed as described above. Next, the display operation when the chrome tape is mounted will be described. When the chrome tape is attached to the first tape recorder, the first detection switch (5) is closed and the first switch (1) is opened. When the first switch (1) is opened, the emitter of the first switching transistor (14) is in the non-grounded state, so that the first switching transistor (14) is inverted to the non-conductive state. When the first switching transistor (14) is inverted to the non-conducting state, the signal applied to the input terminal of the first NOR circuit (7) becomes H level, and therefore the L level signal is output to the output terminal thereof.
As a result, the levels of the signals input to the first input terminal and the second input terminal of the second NOR circuit (9) both become L level, so that an H level signal is output to the output terminal. When an H level signal is output to the output terminal of the second NOR circuit (9), the second drive transistor (2
A bias current flows through the base of 8) and the second drive transistor (28) is turned on. When the second driving transistor (28) is turned on, a driving current flows through the second light emitting diode (23) connected to the collector as a load, and the second light emitting diode (23) is turned on. Therefore, the user can recognize that the chrome tape is attached by turning on the second light emitting diode (23).

As described above, the display operation is performed when the metal tape and the chrome tape are mounted on the first tape recorder. Next, the display operation when the normal tape is mounted will be described. When a normal tape is mounted on the first tape recorder, the first detection switch (5) is closed and the first switch (1) and the second switch (2) are opened. When the first switch (1) is opened, the first switching transistor (14) is inverted to the non-conducting state, so that the input signal of the first NOR circuit (7) becomes H level, and its output terminal has L level signal. Is output. When the second switch (2) is opened, the emitter of the second switching transistor (16) becomes non-grounded.
The switching transistor (16) is turned off. When the second switching transistor (16) is turned off, an H level signal is applied to the second input terminal of the second NOR circuit (9) through the resistor (10).
An L level signal is output to the output terminal of the 2NOR circuit (9). When an L level signal is output to the output terminal of the first NOR circuit (7) and the output terminal of the second NOR circuit (9), the output terminal of the third NOR circuit (11) that receives the signal is of the H level. The signal is output. When an H level signal is output to the output terminal of the third NOR circuit (11), a bias current flows through the resistor (33) to the base of the third driving transistor (31), and the third driving transistor (31). Is turned on. When the third drive transistor (31) is turned on, the third drive transistor (31) is connected to the collector as a load.
A drive current flows through the light emitting diode (24) and the third light emitting diode (24) is turned on. Therefore, the user can recognize that the normal tape is mounted by turning on the third light emitting diode (24).

As described above, the display operation is performed when the metal tape, the chrome tape, and the normal tape are mounted on the first tape recorder. Next, the display operation when each tape is mounted on the second tape recorder will be described. Second
When the metal tape is attached to the tape recorder, the second detection switch (6) is closed. When the second detection switch (6) is closed, the input terminal of the fourth NOR circuit (12) is grounded, so that an H level signal is output to the output terminal of the fourth NOR circuit (12). When an H level signal is output to the output terminal of the fourth NOR circuit (12), the resistors (19) and (2
A bias voltage is applied to the bases of the third switching transistor (18) and the fourth switching transistor (20) via 1), and the third switching transistor (18) and the fourth switching transistor (20) are turned on. Further, since a bias current is supplied to the base of the control transistor (34) from the output terminal of the fourth NOR circuit (12) through the resistor (35), the control transistor (34) becomes conductive. When the third switching transistor (18) becomes conductive, the first N
Since the L level signal is input to the input terminal of the OR circuit (7), the H level signal is output to the output terminal. When an H level signal is output to the output terminal of the first NOR circuit (7), a bias current is supplied to the base of the first driving transistor (25) through the resistor (27) and the first driving transistor (25) is supplied. Since the emitter of 25) is grounded by the conduction of the control transistor (34), the first drive transistor (25) becomes conductive. Therefore, since the drive current flows through the first light emitting diode (22) and the first light emitting diode (22) lights up, it can be recognized that the metal tape is attached. When the metal tape is attached to the second tape recorder, the operation is performed, but when the chrome tape is attached, the third switch (3) is opened and the first NOR circuit (7) is opened.
Output of the second NOR circuit (9) becomes H level, and the second light emitting diode (23) is turned on by conduction of the second drive transistor (28), so that the chrome tape is attached. Can be recognized. When a normal tape is attached, the second switch (3) and the fourth switch (4) are opened and the signals output to the output terminals of the first NOR circuit (7) and the second NOR circuit (9) are at L level. Therefore, an H level signal is output to the output terminal of the third NOR circuit (11). As a result, the third drive transistor (31) is biased into a conductive state and the third light emitting diode (24) is turned on, so that it can be recognized that the normal tape is mounted.

As described above, the display operation is performed when the metal tape, the chrome tape, and the normal tape are attached to the first tape recorder and the second tape recorder, respectively. Next, the cassette is installed in both the first tape recorder and the second tape recorder. The operation when the tape is attached will be described. When the cassette tape is attached to the first tape recorder and the second tape recorder, the first detection switch (5)
And the second detection switch (6) are both closed. When the second detection switch (6) is closed, the fourth NOR circuit (12)
H-level signal is output to the output terminal of the second tape recorder and is used for the display operation of the magnetic tape adhered to the second tape recorder.
Bias is supplied to the bases of the switching transistor (18) and the fourth switching transistor (20). On the other hand, when the second detection switch (6) is closed, the first switching transistor (14) used for the display operation of the magnetic tape mounted on the first tape recorder.
And the bias supply path to the base of the second switching transistor (16) is grounded, and the first switching transistor (14) and the second switching transistor (16) are non-conductive. Therefore, the opening / closing operation of the first switch (1) and the second switch (2) incorporated in the first tape recorder has no effect on the operation of the display circuit. As described above, when the cassette tape is mounted on both the first tape recorder and the second tape recorder, the third switch (3)
Also, since the lighting operation of the first light emitting diode (22), the second light emitting diode (23) and the third light emitting diode (24) is controlled by the opening and closing operation of the fourth switch (4), it can be mounted on the second tape recorder. The type of magnetic tape in use will be displayed with priority.

Although the display operation for displaying the type of the magnetic tape has been described in this embodiment, it is interlocked with the first switch (1), the second switch (2), the third switch (3) and the fourth switch (4). It goes without saying that the reproducing equalizer, the recording equalizer, and the recording bias are configured to be switched corresponding to the magnetic tape by a switch that can be switched.

(G) Effect of the Invention The display circuit of the present invention is the first, second, and third light-emitting diodes that indicate by lighting that the first magnetic tape, the second magnetic tape, and the third magnetic tape are used. When the cassette tape is mounted only on the first tape recorder, the type of the magnetic tape mounted on the first tape recorder is displayed by the first, second and third light emitting diodes. When the cassette tape is attached to the first, second and third
Since the type of magnetic tape that has been installed in the second tape recorder is indicated by the light emitting diode, that is, the display element is also used, the structure is simplified and when only one tape recorder is used. Since the type of the tape is displayed, it is possible to ensure the recognition of the type of the magnetic tape, and the display circuit of the present invention is the most suitable as the display circuit of the double cassette tape recorder.

[Brief description of drawings]

The circuit shown is an embodiment of the display circuit of the present invention. Description of main drawing numbers (1) …… First switch, (2) …… Second switch,
(3) ... third switch, (4) ... fourth switch,
(5) ... First detection switch, (6) ... Second detection switch, (7) ... First NOR circuit, (9) ... Second NOR circuit,
(11) …… 3rd NOR circuit, (12) …… 4th NOR circuit, (14)
...... First switching transistor, (16) …… Second
Switching transistor, (18) ... Third switching transistor, (20) ... Fourth switching transistor, (22) ... First light emitting diode, (23) ...
… Second light emitting diode, (24) …… Third light emitting diode, (25) …… First driving transistor, (28) …… Second driving transistor, (31) …… Third driving transistor, (34) ... … Control transistor.

Claims (1)

[Claims] 1. A function for automatically switching the equalizer or the like according to the characteristics of the first, second and third magnetic tapes having different characteristics by detecting the presence or absence of a recess formed on the rear end surface of the cassette. A cassette-type tape recorder in which the first tape recorder and the second tape recorder provided are incorporated in the same cabinet, wherein the first tape recorder is incorporated in the first tape recorder and the first magnetic tape and the second magnetic tape are detected. First and second switches, a first detection switch which is incorporated in the first tape recorder and detects the presence or absence of a cassette, and a first magnetic tape and a second magnetic tape which are incorporated in the second tape recorder. Third and fourth switches for detecting,
A second detection switch which is incorporated in the second tape recorder and detects the presence / absence of a cassette; and a first magnetic tape which is controlled by the opening / closing operation of each switch,
When the cassette tape is mounted only on the first tape recorder, it is composed of first, second and third light emitting diodes which indicate by lighting that the second magnetic tape and the third magnetic tape are used. 1st, 2nd and 3rd
The type of magnetic tape mounted on the first tape recorder is indicated by the light emitting diode, and the first and second tape tapes are mounted on the second tape recorder when the cassette tape is mounted.
And a display circuit of a cassette type tape recorder, wherein the type of magnetic tape mounted on the second tape recorder is displayed by the third light emitting diode.