JPS634302Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides recording sensitivity for a tape recorder that is equipped with a built-in microphone and an external input jack that has a switching contact that cuts off the signal path from the built-in microphone when a plug is inserted. The present invention relates to a switching circuit, and will be described in detail below with reference to the drawings.

The illustrated circuit is an embodiment of the present invention, and in the same figure, 1 is a built-in microphone, 2 is an external microphone plug or an external input plug from a radio receiver, etc. is inserted, and the plug is inserted. This external input jack is equipped with a switching piece 3 that cuts off the signal path from the built-in microphone 1 when the built-in microphone 1 is turned on. Reference numerals 4 and 5 are recording/playback switching switches, and the illustrated state is the recording state. Reference numeral 6 denotes a sensitivity changeover switch which is manually operated and which changes the recording sensitivity; the first fixed terminal 6a is connected to the signal terminal of the external input jack 2, and the common terminal 6c is connected to the recording side of the recording/playback changeover switch 4. is connected to terminal 4R. Reference numeral 7 designates a recording/playback magnetic head, one end of which is grounded, and the other end connected to the playback side terminal 4P of the recording/playback changeover switch 4 and the recording side terminal 5R of the recording/playback changeover switch 5. 8 is a preamplifier circuit whose input terminal is connected to the common terminal 4C of the recording/playback switch 4; 9 is a recording amplifier circuit into which the signal amplified by the preamplifier circuit 8 is input; ,
The output terminal is connected to the common terminal 5C of the recording/playback switch 5. 10 is a variable resistor that adjusts the level of the output signal of the preamplifier circuit 8;
Reference numeral 11 denotes a main amplifier circuit to which the signal whose level has been adjusted by the variable resistor 10 is input, and 12 an earphone to which the signal amplified by the main amplifier circuit 11 is applied and into which the earphone plug is inserted. It's a joke. Reference numeral 13 denotes an interlocking switch that is switched in conjunction with the operation of attaching and detaching the plug to the external input jack 2, and the illustrated state is a state in which no plug is inserted. 14 is a first sensitivity switching resistor connected between the first fixed terminal 6a and the second fixed terminal 6b of the sensitivity switching switch 6; 15 is a resistance between the second fixed terminal 6b of the sensitivity switching switch 6 and the interlocking switch 13; A second sensitivity switching resistor 16 is connected between the second fixed terminal 6b of the sensitivity switching switch 6 and the second fixed terminal 13b of the first interlocking switch 13. This is a third sensitivity switching resistor. In this configuration, the resistance value of the third sensitivity switching resistor 16 is set to a smaller value than the resistance value of the second sensitivity switching resistor 15, and the common terminal 13c of the interlocking switch 13 is grounded.

The present invention is constructed as described above, and its operation will be explained next. First, the reproduction operation will be explained. In the reproduction operation state, the recording and reproduction changeover switches 4 and 5 are in a state opposite to the state shown in the figure. In such a reproducing operation state, the signal reproduced by the recording/reproducing magnetic head 7 is inputted to the preamplifier circuit 8 through the recording/reproducing switch 4. The reproduced signal input to the preamplifier circuit 8 is amplified, its level is adjusted by a variable resistor 10, and then input to the main amplifier circuit 11. The reproduced signal input to the main amplifier circuit 11 is amplified and applied to the earphone jack 12, and is listened to by the earphone plugged into the earphone jack 12.

Although the playback operation is performed as described above, the recording operation will be explained next. When the user performs a recording operation, the recording/reproduction changeover switches 4 and 5 are switched to the state shown, and the tape recorder enters the recording operation state. First, a case will be described in which a signal obtained from the built-in microphone 1 is recorded. The recording signal converted into an electric signal by the built-in microphone 1 is input to the preamplifier circuit 8 through the switching contact 3 of the external input jack 2, the sensitivity selection switch 6, and the recording/playback selection switch 4. The recording signal input to the preamplifier circuit 8 is amplified and then input to the recording amplifier circuit 9. The recording amplifier circuit 9
After being further amplified, the recording signal input to the recording/playback switch 5 is applied to the recording/playback magnetic head 7 together with a bias signal from a bias oscillation circuit (not shown), and is recorded on a magnetic tape. In such a state, the recording signal from the built-in microphone 1 is input to the preamplifier circuit 8 through the switching contact 3 of the external input jack 2, the sensitivity selection switch 6, and the recording/playback selection switch 4.
Recording will be performed with high sensitivity without the signal level being attenuated. Therefore, such a recording operation is effective when recording a large number of sounds from a conference or the like. In this way, when recording a meeting, etc., a highly sensitive recording characteristic is required, but when recording a dictation, the recording level becomes excessive in the above-mentioned high sensitivity state, causing a problem. Such dictation recording is performed by switching the sensitivity changeover switch 6 to the opposite side from the state shown in the figure. When the sensitivity selection switch 6 is switched to the opposite side from the state shown in the figure, the recording signal from the built-in microphone 1 passes through the switching contact piece 3 of the external input jack 2, and then passes through the first sensitivity switching resistor 14 and the second sensitivity switching resistor 14. The signal is divided by a two-sensitivity switching resistor 15, and then input to a preamplifier circuit 8 through a sensitivity switching switch 6 and a recording/playback switching switch 4. That is, the sensitivity selector switch 6
is switched, the built-in microphone 1
Since the level of the recording signal from the recording signal is attenuated by the first sensitivity switching resistor 14 and the second sensitivity switching resistor 15, the recording signal is recorded at low sensitivity. Therefore, such a recording operation is suitable for performing dictation recording.

The recording operation using the built-in microphone 1 is carried out as described above. Next, the case where a signal obtained through the external input jack 2 is recorded will be explained. First, a case will be described in which a plug of an external microphone is inserted into the external input jack 2 to record a sound. When the external microphone plug is inserted into the external input jack 2, the interlock switch 13
is switched to the opposite side of the state shown. When the sensitivity selector switch 6 is in the state shown, the recording signal from the external microphone input to the external input jack 2 is input to the preamplifier circuit 8 through the sensitivity selector switch 6 and the recording/playback selector switch 4, and is recorded. Therefore, high-sensitivity recording operation can be performed. In addition, when the sensitivity changeover switch 6 is switched to the opposite side, the first sensitivity changeover resistor 14
Since the amount of attenuation caused by the third sensitivity switching resistor 16 is large, recording with an external microphone is impossible, and by performing such a switching operation, a portion similar to the no-signal recording portion can be formed on the magnetic tape. .

The recording operation using the external microphone is carried out as described above. Next, the case of recording signals from a radio receiver, television, etc., using a connecting plug will be explained. When such a connecting plug is inserted into the external input jack 2, the interlock switch 1 is turned on as described above.
3 is switched to the opposite position from the illustrated position. The level of the recording signal input to the external input jack 2 from a radio receiver, television, etc. is very high compared to the level of the recording signal obtained from the built-in microphone 1 or the external microphone. Therefore, when the sensitivity switch 6 is in the illustrated position, the input is excessively high and the recording signal is significantly distorted, so that the recording operation of such a signal is performed by switching the sensitivity switch 6 to the opposite position from the illustrated position. When the sensitivity switch 6 is in the switched state, the recording signal input to the external input jack 2 is divided by the first sensitivity switching resistor 14 and the third sensitivity switching resistor 16, and then input to the pre-amplifier circuit 8 through the sensitivity switch 6 and the recording/playback switch 4. Therefore, the high-level recording signal input to the external input jack 2 is divided by the first sensitivity switching resistor 14 and the third sensitivity switching resistor 16, and then input to the pre-amplifier circuit 8 through the sensitivity switch 6 and the recording/playback switch 4.
Since the level is attenuated to an appropriate level by 6, a satisfactory recording operation can be performed.

As mentioned above, each recording operation is performed, but since the recording signal which is the output signal of the preamplifier circuit 8 is input to the main amplifier circuit 11 through the variable resistor 10, an earphone plug is inserted into the earphone jack 12. Then, the recording signal can be listened to, ie, monitored.

As explained above, the present invention provides at least the first and second sensitivity switches by switching the sensitivity selector switch which is switched manually and the interlocking switch which is switched in conjunction with the insertion of the plug into the external input jack.
and third recording sensitivity, it is possible to obtain good recording characteristics according to the recording signal source, and it is also possible to record signals with different recording levels with a single external input jack. Because I can,
This is highly effective when implemented in a micro-compact tape recorder in which it is not possible to provide many input jacks.

[Brief explanation of the drawing]

The illustrated circuit is an embodiment of the recording sensitivity switching circuit of the present invention. Explanation of main figure numbers, 1...Built-in microphone,
2...External input jack, 6...Sensitivity selection switch, 7...Magnetic head for recording and playback, 8...Preamplifier circuit, 9...Recording amplifier circuit, 11...Main amplifier circuit, 13...Interlocking Switch, 14... Resistor for first sensitivity switching, 15... Resistor for second sensitivity switching, 1
6...Third sensitivity switching resistor.

Claims (1)

[Scope of utility model registration request] In a tape recorder equipped with a built-in microphone and an external input jack having a switching piece that cuts off the signal path from the built-in microphone when a plug is inserted, the sensitivity is manually switched and the recording sensitivity is switched. It consists of a changeover switch and an interlocking switch that is switched in conjunction with the insertion of a plug into the external input jack, and at least first, second, and third recording sensitivities are obtained by switching the sensitivity changeover switch and the interlocking switch. A recording sensitivity switching circuit for a tape recorder, characterized in that: