JPH0785585A - Tape recorder - Google Patents

Abstract

PURPOSE:To automatically switch an inside microphone and an outside microphone by the inserting state of the outside microphone by making an earphone jack and an outside microphone jack into one jack. CONSTITUTION:The operation or nonoperation of the inside microphone 34 is performed by turning on and off a transistor 32. The inside microphone 34 is not operated by turning off the transistor 32 when an outside microphone plug or an earphone plug 43 with the outside microphone is inserted to the jack 21, and the inside microphone 34 is operated by turning on the transistor 32 at other time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact recordable tape recorder having an internal microphone.

[0002]

2. Description of the Related Art In recent years, recordable tape recorders using magnetic tape cassettes have become smaller and more portable.
Along with this, miniaturization of parts used and reduction of the number of parts are remarkable. As one of them, a system in which the earphone jack and the microphone jack are integrated has been proposed (Japanese Patent Laid-Open No. 6-242242).
2-88105). There is also proposed a method of automatically switching between operating the external microphone and operating the internal microphone depending on the insertion state of the external microphone plug (Japanese Patent Laid-Open No. 59-188809).

A conventional example of a system in which an earphone jack and a microphone jack are integrated will be described below with reference to the drawings. FIG. 3 is a circuit block diagram of a conventional tape recorder. In FIG. 3, 1 is a jack into which each plug of an earphone and a microphone is inserted, 2 is a switch for switching between earphone output and microphone input, 3 is a microphone amplifier, 4 is a power amplifier, 5 is a recording / playback amplifier, and 6 is a recording / playback amplifier. It is a reproducing head.

FIG. 4 is a structural diagram of a jack and a plug for switching the jack shown in FIG. 3, and shows the relationship between the earphone jack 7, the microphone unit 8 and the changeover switch 9. The change-over switch 9 is for switching between earphone output and microphone input, and the microphone unit 8 is provided with a column 10 for operating a switch for switching between earphone output and microphone input.

The operation of the tape recorder configured as described above will be described. First, during reproduction, a signal output from the recording / reproducing head 6 is amplified by the recording / reproducing amplifier 5 and the power amplifier 4, and is connected to the earphone from the jack 1 via the changeover switch 2. In this reproduction state, the movable terminal 2a of the changeover switch 2 is one fixed terminal 2a.
The power amplifier 4 and the jack 1 are connected in the state of being connected to the b side. During recording, a recording signal input from the microphone unit 8 passes from the jack 1 through the changeover switch 2, is amplified by the microphone amplifier 3 and the recording / reproducing amplifier 5, and is recorded on the tape via the recording / reproducing head 6.
In this recording state, the movable terminal 2a of the changeover switch 2 is connected to the other fixed terminal 2c side, and the jack 1 and the microphone amplifier 3 are connected. Changeover switch 9
When the earphone plug is inserted, the movable part of the switch is in a protruding state, and the circuit is in a state in which the earphone output is given to the jack 1. When the microphone unit 8 is inserted, the changeover switch 9 is pushed in by the column 10, and the circuit enters a state in which the microphone input given to the jack 1 is applied to the microphone amplifier 3. Therefore, switching between reproduction and recording of the jack 1 can be automatically performed by inserting the microphone unit 8 into the jack 1.

Next, a conventional example of a system for automatically switching whether to enable the external microphone or the internal microphone according to the insertion state of the external microphone plug will be described. Figure 5
It is a circuit block diagram of the conventional tape recorder. Reference numeral 11 denotes a power source, and an external microphone and an internal microphone 12 not shown.
A DC bias voltage is applied to. Reference numeral 13 is a resistor for controlling a DC bias voltage applied to an external microphone and an internal microphone (not shown). Reference numeral 14 is a capacitor for cutting the DC bias voltage for the external microphone, and 15 is a capacitor for cutting the DC bias voltage for the internal microphone. Reference numeral 16 is a recording amplifier, and 17 is a recording head. With the recording head 17,
The recording signal amplified by the recording amplifier 16 can be recorded on the tape. Reference numeral 18 is a jack into which an external microphone plug is inserted, and a sleeve terminal 18a of this jack 18
Is grounded. Switch terminal 18c of jack 18
Is connected to the internal microphone 12 and the condenser 15.
The chip terminal 18b of the jack 18 is connected to the resistor 13 and the capacitor 14.

The operation of the tape recorder constructed as described above will be described below. When the external microphone plug is not inserted in jack 18, switch terminal 1
Since 8c is in contact with the chip terminal 18b, a voltage is applied to the internal microphone 12 via the resistor 13. Therefore, the internal microphone 12 can convert sound into an electric signal. The signal captured by the internal microphone 12 is A
It is set to C, amplified by the recording amplifier 16, and recorded on the tape by the recording head 17. When the external microphone plug is inserted in the jack 18, the switch terminal 18
c is separated from the chip terminal 18b. Therefore, at this time, no voltage is applied to the internal microphone 12. The external microphone is connected to the DC from the resistor 13 through the chip terminal 18b.
Since the bias voltage is applied, the sound can be converted into an electric signal by the external microphone. At this time, the captured signal is converted into AC by the condenser 14, amplified by the recording amplifier 16, and recorded on the tape by the recording head 17.

[0008]

However, in the conventional structure as described above, it is possible to switch between the internal microphone and the external microphone or the earphone and the external microphone with one jack, but both of them can be switched. Since two jacks are required to perform the operation, the space occupied by the jacks becomes large, and there is a problem that it becomes an obstacle to miniaturization of the tape recorder.

[0009]

In order to solve the above problems, a tape recorder according to the present invention has an internal microphone, a plug for an earphone, a plug for an external microphone, or a plug for an earphone with an external microphone. And a switch means capable of switching between an internal microphone and an external microphone according to the insertion state of a plug into this jack.

[0010]

According to the present invention, since the earphone jack and the external microphone jack can be integrated into one by the above structure, the space occupied by the jack can be reduced and the cost can be reduced at a low cost. Further, it is possible to automatically switch between the internal microphone and the external microphone according to the insertion state of the external microphone.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram mainly showing an input / output jack portion of a tape recorder according to an embodiment of the present invention. Reference numeral 21 is an input / output jack, and a sleeve terminal 21a of this jack 21 is grounded. The ring terminal 21b of the jack 21 is connected to the input side of the switching circuit 25 for switching between the external microphone and the internal microphone. Further, the chip terminal 21c of the jack 21 is connected to the output side of the reproduction amplifier 22 so that the reproduction output signal from the reproduction head 23 can be received via the reproduction amplifier 22.
A recording amplifier 24 is connected to the output side of the switching circuit 25. A recording head 26 records a recording signal amplified by the recording amplifier 24 on a tape.

Next, a detailed circuit configuration of the switching circuit 25 will be described. A power source 27 applies a DC bias voltage to an external microphone and an internal microphone 34 (not shown). Reference numeral 28 is a resistor for controlling a DC bias voltage applied to an external microphone (not shown), and 29 is a capacitor for cutting off a DC bias voltage for the external microphone. Reference numeral 30 is a resistor for controlling the DC bias voltage applied to the internal microphone 34, and 31 is a capacitor for cutting off the DC bias voltage for the internal microphone. 32 is a transistor, and the internal microphone 24
Also, switch the external microphone. 33 is a resistance,
It controls the base current of the transistor 32.

2 (a), (b) and (c) are structural views of the plugs inserted into the jacks 21, respectively. Figure 2
The earphone plug 41 shown in (a) has a sleeve 41a, a ring 41b and a tip 41c which are insulated from each other. Similarly, the external microphone plug 4 shown in FIG.
2 is a sleeve 42a and a ring 42b which are insulated from each other
2C, and the earphone plug 43 with an external microphone shown in FIG. 2C also has a sleeve 43a, a ring 43b and a tip 43c which are insulated from each other.
The tip 41c and the sleeve 41a of the earphone plug 41 and the tip 43c and the sleeve 43a of the earphone plug 43 with an external microphone are connected to the earphone via cords, respectively. The ring 41b of the earphone plug 41 and the tip 42c of the external microphone plug 42 are not connected to any of them and are independent. Also an external microphone plug 4
The ring 42b, the sleeve 42a, the ring 43b and the sleeve 43a of the earphone plug 43 with the external microphone are
Each is connected to an external microphone via a cord.

The earphone plug 41 configured as described above
Is inserted into the jack 21, the chip 41c is connected to the output side of the reproduction amplifier 22 through the chip terminal 21c of the jack 21, and the sleeve 41a is grounded through the sleeve terminal 21a of the jack 21. Further, the ring 41b of the earphone plug 41 is connected to the ring terminal 21b of the jack 21, but since the ring 41b is not connected to anything, it has no influence on the switching circuit 25. At the time of reproduction with the earphone plug 41 inserted in the jack 21, the earphone is inserted between the sleeve terminal 21a and the chip terminal 21c, so the reproduction signal from the reproduction head 23 is reproduced by the reproduction amplifier 22.
The amplified signal is output by the earphone and can be output from the playback signal. Further, at the time of recording, the ring terminal 21b is in an independent state, so that the resistance in which the resistance 28 and the resistance 33 are connected in series to the transistor 32 is used as the base resistance. At this time, since the resistor 28 is connected to the power source 27, a current flows into the base of the transistor 32 and a current flows between the collector and the emitter.
As a result, a current flows through the resistor 30 and the internal microphone 34
Since a voltage is applied to the internal microphone 34, the internal microphone 34 can convert sound into an electric signal. The signal taken in by the internal microphone 34 is converted into the AC component by the capacitor 31, and the recording amplifier 2
It is amplified at 4 and recorded on the tape by the recording head 26.

Next, connect the external microphone plug 42 to the jack 2
1 when inserted into the external microphone plug 42 tip 42c
Is connected to the chip terminal 21c of the jack 21,
Since the chip 42c is not connected to anything, it has no influence on the reproduction amplifier 22. The ring 42b of the external microphone plug 42 is connected to the switching circuit 25 through the ring terminal 21b of the jack 21. At the time of reproduction, since the chip terminal 21c of the jack 21 is not connected to anything, the reproduction signal from the reproduction head 23 is amplified by the reproduction amplifier 22 but is not output. Further, at the time of recording, since the DC bias voltage is applied to the external microphone through the resistor 28 through the ring terminal 21b, the sound can be converted into an electric signal by the external microphone. At this time, the captured signal is converted into AC by the capacitor 29, amplified by the recording amplifier 24, and recorded on the tape by the recording head 26. During recording, the voltage of the ring terminal 21b is set to 0.7 V or less due to the relationship between the external microphone and the resistor 28. By this,
Since no base current flows, no current flows between the collector and emitter of the transistor 32. Therefore, since no current flows through the resistor 30, no voltage is applied to the internal microphone 34, and sound is not converted into an electric signal.

Next, when the earphone plug 43 with an external microphone is inserted into the jack 21, the chip 43c is inserted into the jack 2.
It is connected to the output side of the reproduction amplifier 22 through one chip terminal 21c, and the sleeve 43a is grounded through the sleeve terminal 21a of the jack 21. The ring 43b is connected to the switching circuit 25 through the ring terminal 21b of the jack 21. At the time of reproduction, the reproduction signal can be output from the earphone in the same manner as when the earphone plug 41 is inserted. At the time of recording, after the sound is converted into an electric signal by the external microphone in the same manner as when the external microphone plug 42 is inserted, the capacitor 29 makes only AC, the recording amplifier 24 amplifies, and the recording head 26 records the tape. . Further, since no voltage is applied to the internal microphone 34, sound is not converted into an electric signal.

Finally, the case where none of the earphone plug 41, the external microphone plug 42, and the earphone plug 43 with an external microphone is inserted will be described. At the time of reproduction, since the chip terminal 21c of the jack 21 is not connected to anything, the reproduction signal from the reproduction head 23 is amplified by the reproduction amplifier 22 but is not output. Further, at the time of recording, the state is the same as when the earphone plug 41 is inserted. Therefore, the sound is converted into an electric signal by the internal microphone 34, only the AC component is converted by the condenser 31, the sound is amplified by the recording amplifier 24, and the recording head 26 Recorded on tape by.

As described above, the earphone jack and the external microphone jack can be combined into one jack, and the switching between the internal microphone and the external microphone can be automatically switched depending on the inserted state of the external microphone.

In the above embodiment, the case where the NPN transistor is used has been described. However, it is needless to say that the same effect can be obtained with almost the same circuit configuration even if the PNP transistor is used. The same effect can be obtained when the transistor portion is a mechanical switch that is automatically switched when various plugs are inserted.

[0021]

As described above, according to the present invention, the earphone jack and the external microphone jack can be integrated into one jack, and the internal microphone and the external microphone can be automatically switched depending on the inserted state of the external microphone. It is easy to use and the tape recorder can be miniaturized at low cost.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a tape recorder according to an embodiment of the present invention.

FIG. 2A is a structural diagram of an earphone plug used in a tape recorder according to an embodiment of the present invention. FIG. 2B is a structural diagram of an external microphone plug used in a tape recorder according to an embodiment of the present invention. Of the earphone plug with external microphone of the earphone plug used in the tape recorder in one embodiment

FIG. 3 is a circuit block diagram of a conventional tape recorder.

FIG. 4 is a structural diagram of a conventional jack and plug.

FIG. 5 is a circuit block diagram of a conventional tape recorder.

[Explanation of symbols]

 21 Jack 21a Sleeve Terminal 21b Ring Terminal 21c Chip Terminal 25 Switching Circuit 32 Transistor 34 Internal Microphone 41 Earphone Plug 42 External Microphone Plug 43 Earphone Plug with External Microphone

Claims (1)

[Claims] 1. A jack to which either an internal microphone, a plug for an earphone, a plug for an external microphone, or a plug for an earphone with an external microphone can be connected, and an internal jack depending on the insertion state of the plug into this jack. A tape recorder having switch means for switching between a microphone and an external microphone.