JPH0329787Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Field of industrial application The present invention relates to a tape recorder having a playback function in a first direction and a playback function in a second direction opposite to the first direction. The present invention relates to a circuit that displays the running direction of a magnetic tape, that is, the reproduction direction. (b) Prior Art Recently, tape recorders called head-on stereos, in which the reproduced sound of a magnetic tape can be heard using a head-on, have become popular. A tape recorder built into such a head-on stereo generally has a playback function in a second direction, which is the opposite direction to the first direction, in addition to a playback function in the first direction. A tape recorder having such a bidirectional playback function is equipped with a means for indicating in which direction the playback operation is being performed. There is one disclosed in Publication No. 56-93892. (c) Problems to be solved by the invention Although the display circuit disclosed in the above-mentioned publication can display the direction of playback of a magnetic tape, it is possible to display the playback direction of a magnetic tape, but it is not possible to The conduction of the transistor connected in the bias circuit of one light emitting diode
Since the lighting operation of the two light emitting diodes is controlled by non-conducting operation, it is not possible to easily set the operating point or design to make the brightness of the two light emitting diodes the same. have. The present invention aims to provide a playback direction display circuit with a simple circuit configuration. (d) Means for solving the problem The present invention includes a changeover switch that opens and closes in accordance with the driving direction of the magnetic tape, and when the changeover switch is in the closed state, the changeover switch connects the power supply line and the ground. a first voltage divider circuit comprising first and second resistors connected in series with each other; and a first voltage divider circuit having an anode connected to a power supply line and a cathode connected to a voltage division point of the first voltage divider circuit. light emitting diode,
A display control transistor is in a non-conductive state when the changeover switch is in a closed state, and is in a conductive state by being supplied with a bias current through the first voltage dividing circuit when the changeover switch is in an open state, and the display transistor is in a conductive state. a second voltage divider circuit consisting of a first and second resistor connected in series between the power supply line and the ground by the display control transistor when in the state; and a second light emitting diode connected to the voltage dividing point of the two voltage dividing circuit. (E) Function The present invention includes a first light emitting diode and a second light emitting diode whose operation is controlled by the first voltage dividing circuit and whose lighting indicates that the regeneration operation is being performed in the first direction. A second light emitting diode is provided whose operation is controlled by a voltage divider circuit and which lights up to indicate that a reproduction operation is being performed in the second direction. conduction and
The operation of the first light emitting diode and the second light emitting diode is controlled by a display control transistor whose non-conducting operation is controlled. (F) Embodiment The illustrated circuit is an embodiment of the reproduction direction display circuit of the present invention. In the illustrated circuit, 1 is a first magnetic head that reproduces a signal recorded on a track in a first direction of the magnetic tape, and 2 is a first magnetic head that reproduces a signal recorded on a track in a second direction of a magnetic tape. A second magnetic head 3 receives the signal reproduced by the first magnetic head 1 or the second magnetic head 2, and is also input to a preamplifier circuit 4 for amplifying the signal. This is a selective amplification circuit incorporating a switch circuit 5 that selects and electronically switches a signal, and a first input terminal 6 to which the signal reproduced by the first magnetic head 1 is applied, and a second magnetic head 2. A second input terminal 7 to which a reproduced signal is applied, a power terminal 9 connected to a power supply line 8, a ground terminal 10 which is grounded, and an output terminal 11 to which an output signal of the preamplifier circuit 4 is applied. and a control terminal 12 for controlling the operation of the switch circuit 5. In such a configuration, when the control terminal 12 is not grounded, the signal applied to the first input terminal 6 is input to the preamplifier circuit 4, and when the control terminal 12 is grounded, the signal applied to the second input terminal 6 is input to the preamplifier circuit 4. The switch circuit 5 is configured so that the signal applied to the input terminal 7 is input to the preamplifier circuit 4. 13 is a variable resistor to which a signal output to the output terminal 11 is applied and adjusts the level of the signal; 14 is a variable resistor to which a signal whose level has been adjusted by the variable resistor 13 is applied and which adjusts the level of the signal; This is the main amplification circuit for amplification. Reference numeral 15 denotes a headphone jack into which a headphone plug is inserted, and the main amplifier circuit 1
The signal terminal 16 is provided with a signal terminal 16 to which a No. 4 output signal is applied, and a ground terminal 17 that is grounded. 18 is a battery which is a power source; 19 is a changeover switch which is closed when the magnetic tape drive mechanism is driven in the first direction and opened when it is driven in the second direction; It has a first terminal 19a and a second terminal 19b that are grounded. A first terminal 20 is connected in series between the power supply line 8 and the second terminal 19b of the changeover switch 19.
A first voltage dividing circuit comprising a resistor 21 and a second resistor 22; 23 is a first light emitting circuit whose anode is connected to the power supply line 8 and whose cathode is connected to the voltage dividing point A of the first voltage dividing circuit 20 ; It is a diode. 24 is a display control transistor whose emitter is grounded and whose base is connected to the second terminal 19b of the changeover switch 19 via a resistor 25; 26 is a power supply line 8 and a collector of the display control transistor 24; A second voltage divider circuit 29 has an anode connected to the power supply line 8 and a cathode connected to the voltage divider circuit 26 of the second voltage divider circuit 26. A second light emitting diode connected to point B. 30 is a switching transistor whose collector is connected to the control terminal 12 and whose emitter is grounded in order to control the operation of the switch circuit 5; its base is connected to the second terminal of the changeover switch 19 via a resistor 31; 19b. In such a configuration, the first voltage dividing circuit 2
0 and the first resistor 2 constituting the second voltage dividing circuit 26
The resistance values of the resistors 1 and 27 and the second resistors 22 and 28 are set so that the first light emitting diode 23 and the second light emitting diode 29 do not light up when the voltage of the battery 18 drops below a predetermined voltage value. Further, the resistance values of the resistors 25 and 31 inserted and connected to the base circuits of the display control transistor 24 and the switching transistor 30, respectively, are the same as those of the first voltage dividing circuit 2.
0, and when the base current is supplied to the transistors 24 and 30, the first light emitting diode 23 lights up. It is recommended not to do so. The reproduction direction display circuit of the present invention is constructed as described above, and its operation will be explained below. When the user performs a playback operation, the drive mechanism enters a state for performing a playback operation, and power is supplied to each circuit from the battery 18, and the tape recorder enters a playback state.First, the playback operation in the first direction will be explained. do. When the reproduction operation is in the first direction, the changeover switch 19 is in a closed state, so the display control transistor 24 and the changeover transistor 30 are not biased and are in a non-conducting state. Therefore, the control terminal 1 of the switch circuit 5
2 is in an ungrounded state, and in such a state, the signal applied to the first input terminal 6 is input to the preamplifier circuit 4. Therefore, the signal reproduced by the first magnetic head 1 is transmitted to the preamplifier circuit 4.
The signal is input to the output terminal 11, amplified, and then output to the output terminal 11. The reproduced signal outputted to the output terminal 11 is applied to the variable resistor 13 to have its level adjusted, and then applied to the input terminal of the main amplifier circuit 14. The signal input to the main amplifier circuit 14 is amplified and then sent to the signal terminal 1 constituting the headphone jack 15 .
6, so by inserting the headphone plug into the headphone jack 15 , the signal recorded on the magnetic tape in the first direction can be reproduced and listened to by the headphone. Through this operation, the reproducing operation in the first direction is performed, but when the reproducing operation in the first direction is in the state, the display control transistor 24 is in a non-conducting state, so one end of the second voltage dividing circuit 26 is grounded. without being
The second light emitting diode 29 is in a non-lighting state. In this state, since one end of the first voltage dividing circuit 20 is grounded by the changeover switch 19, the first light emitting diode 23 controlled by the first voltage dividing circuit 20 is in a lighting state. become. In this way, when the tape recorder is in the playback operation state in the first direction, the first light emitting diode 23
lights up, the user must switch on the first light emitting diode 2.
3 lights up, it can be recognized that the reproducing operation in the first direction is being performed. As described above, the reproduction operation in the first direction is performed in this embodiment. Next, the reproduction operation in the second direction, which is the opposite direction to the first direction, will be explained. The reproduction operation in the second direction is performed by operating a reproduction direction switching knob or by a device that detects the end of the magnetic tape. When the reproduction direction is switched, the magnetic tape drive mechanism becomes driven in the second direction, and the changeover switch 19 is opened in conjunction with the switching. When the changeover switch 19 is opened, a bias current flows to the bases of the display control transistor 24 and the changeover transistor 30 through the first resistor 21 and second resistor 22 constituting the first voltage divider circuit 20, and the display control transistor 24 and switching transistor 30 become conductive. When the switching transistor 30 becomes conductive, the control terminal 12 of the switch circuit 5 is grounded, so that the switching operation of the switch circuit 5 is performed, and the signal applied to the second input terminal 7 is input to the preamplifier circuit 4. to be in a state of being Therefore, the signal reproduced by the second magnetic head 2 is input to the preamplifier circuit 4, amplified, and then output to the output terminal 11. The signal output to the output terminal 11 is level-adjusted and amplified by the variable resistor 13 and the main amplifier circuit 14, respectively, and then applied to the signal terminal 16 constituting the headphone jack 15. The headphone jack 1
5, it is possible to play back and listen to the signals in the second direction recorded on the magnetic tape using the headphone. In this way, the reproducing operation in the second direction is performed, but when the reproducing operation is in the second direction, one end of the second voltage dividing circuit 26 is grounded by the display control transistor 24. The second light emitting diode 29 controlled by the second voltage dividing circuit 26 is in a lighting state. In this state, the base currents of the display control transistor 24 and the switching transistor 30 flow through the first voltage dividing circuit 20, but the first light emitting diode 23 does not light up. In this way, when the tape recorder is in the state of playback operation in the second direction, the second light emitting diode 29 is lit, so that the user can perform the playback operation in the second direction by turning on the second light emitting diode 29. It is possible to recognize that something is happening. As explained above, tape recorders are the first
In the playback operation state in the direction and in the second direction, the playback direction is displayed by lighting the first light emitting diode 23 and the second light emitting diode 29.
The voltage display operation will be explained. When the regeneration operation in the first direction is being performed, the first light emitting diode 2 is controlled by the potential control of the first voltage dividing circuit 20.
3 is in a lighting state, but when the voltage of the battery 18 drops below a predetermined value, that is, the voltage value necessary for operating the tape recorder while in such a state, the first light emitting diode 23 becomes a non-lighting state. .
Therefore, the user can recognize that the voltage of the battery 18 has decreased and that the battery 18 needs to be replaced. The voltage display operation is performed when the first light emitting diode 23 is lit and the regeneration operation is performed in the first direction, but next, the operation when the regeneration operation is performed in the second direction will be explained. do. While the regeneration operation in the second direction is being performed, the second light emitting diode 29 is in a lighting state due to the potential control of the second voltage dividing circuit 26 , but the voltage of the battery 18 drops below the predetermined value mentioned above. Then, the second light emitting diode 29 is turned off.
Therefore, even when the reproducing operation is in the second direction, the user can recognize that the voltage of the battery 18 has decreased and that the battery 18 needs to be replaced. In this explanation, the display operation of the playback direction has been explained, but if the changeover switch 19 is associated with a drive mechanism for fast forwarding and rewinding operations, it is possible to display the running direction of the magnetic tape during fast forwarding and rewinding operations. I can do it. Further, even in such a configuration, the power supply voltage can be displayed by the first light emitting diode 23 and the second light emitting diode 29. Further, in this embodiment, a monaural tape recorder has been described, but it is of course possible to implement the present invention in a stereo type tape recorder. (g) Effects of the invention The playback direction indicating circuit of the present invention not only displays the playback direction of the magnetic tape using the first and second light emitting diodes, but also amplifies the switching and lighting operation of the light emitting diodes. The switching operation of the magnetic head connected to the circuit is controlled by using the opening and closing operation of a changeover switch, that is, the switching operation is controlled by a switch with one contact per circuit. It is characterized by
By doing this, there is no need to increase the number of switches or contacts, which simplifies the circuit and mechanical configuration and allows the use of inexpensive switches. This has a very large effect on downsizing the recorder. The present invention also provides a first voltage dividing circuit and a second voltage dividing circuit whose operations are respectively controlled by the changeover switch and a display control transistor whose operation is controlled by the changeover switch.
Since the lighting operation of the first light emitting diode and the second light emitting diode is controlled by the function of the voltage dividing circuit, not only can the operating points of lighting and non-lighting be set accurately, but also the two This invention has the advantage that the luminance of the light emitting diodes can be easily made the same, and the practical value of the present invention is very high.

[Brief explanation of drawings]

The illustrated circuit is an embodiment of the reproduction direction display circuit of the present invention. Explanation of main drawing numbers, 1...first magnetic head, 2...
...Second magnetic head, 3 ...Selective amplifier circuit, 4...
Preamplifier circuit, 5... Switch circuit, 8... Power supply line, 14... Main amplifier circuit, 18... Battery, 19
...Selector switch, 20 ...First voltage divider circuit, 23
...First light emitting diode, 24...Display control transistor, 26 ...Second voltage dividing circuit, 29...
Second light emitting diode, 30... switching transistor.

Claims (1)

[Scope of utility model registration request] In a tape recorder having a playback function in a first direction and a playback function in a second direction opposite to the first direction, a first tape recorder that plays back a signal recorded on a track in the first direction of the magnetic tape a magnetic head; a second magnetic head for reproducing a signal recorded on a track in a second direction of the magnetic tape; and a signal reproduced by the first magnetic head or the second magnetic head being selectively applied to an amplifier circuit. a selective amplifier circuit incorporating a switch circuit for guiding the switch circuit and having a control terminal for controlling the operation of the switch circuit; a changeover switch, and first and second resistors connected in series between the power supply line and ground by the changeover switch when the changeover switch is in the closed state.
a voltage dividing circuit; a first light emitting diode having an anode connected to a power supply line and a cathode connected to a voltage dividing point of the first voltage dividing circuit; and a first light emitting diode having a non-conducting state when the changeover switch is in a closed state. a display control transistor which is turned on by supplying a bias current through the first voltage divider circuit when the display control transistor is in the open state and is in the open state; a second voltage divider circuit comprising first and second resistors connected in series between the line and ground; an anode connected to the power line and a cathode connected to a voltage dividing point of the second voltage divider circuit; and a second light emitting diode connected to the amplifier circuit by the control operation of the switch circuit by the opening/closing operation of the changeover switch, and the changeover switch is in a closed state. At times, the first voltage dividing circuit causes the first light emitting diode to light up, and when the changeover switch is in an open state, the second voltage dividing circuit causes the display control transistor to conduct. A playback direction display circuit for a tape recorder with a bidirectional playback function, characterized in that the second light emitting diode is turned on, and the first light emitting diode and the second light emitting diode are turned on to indicate the playback direction of the magnetic tape. .