Dynamic magnetic information storage or retrieval – General recording or reproducing – Signal switching
Reexamination Certificate
1998-03-17
2001-03-06
Kim, W. Chris (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Signal switching
Reexamination Certificate
active
06198586
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a voice recording/playback apparatus adapted to record a voice signal in a recording medium and play back a recorded voice signal from the recording medium.
(2) Description of the Related Art
A compact-disk (CD) radio cassette tape recorder system in which a CD playback unit, a radio unit and a cassette tape recorder unit are integrally provided is known. In an existing voice recording/playback apparatus of this type, a built-in microphone is provided to record a voice signal in a magnetic tape during a microphone voice recording mode. In order to perform the microphone voice recording mode, a mode selection switch of the CD radio cassette tape recorder system is set by a user.
If a speaker unit outputs a voice during the microphone voice recording mode, the voice is captured by the built-in microphone which causes occurrence of howling. To avoid howling, it is necessary that the outputting of a voice by the speaker unit during the microphone voice recording mode be inhibited.
Generally, in order to inhibit the outputting of a voice by the speaker unit during the microphone voice recording mode, an input of a playback head amplifier unit of the CD radio cassette tape recorder system is set in a muted condition.
FIG. 3
shows a conventional voice recording/playback apparatus of the above-described type.
The conventional voice recording/playback apparatus
1
of
FIG. 3
is applied to, for example, an existing CD radio cassette tape recorder system.
As shown in
FIG. 3
, the conventional voice recording/playback apparatus
1
includes a tape recorder unit
3
which records a voice signal in a magnetic tape
2
and plays back a recorded voice signal from the magnetic tape
2
. A CD playback unit
4
provides a voice signal (or a playback signal) derived from a recorded voice signal of a compact disk (CD). A radio unit
5
provides a voice signal (or a demodulated signal) derived from a radio signal transmitted by a radio broadcast station. A built-in microphone unit
6
provides a voice signal derived from an external voice.
In the conventional voice recording/playback apparatus
1
, a mode selection switch
7
is provided to select one of a plurality of operational modes of the conventional voice recording/playback apparatus
1
. The operational modes include, for example, a tape playback mode, a microphone voice recording mode, a radio output mode, a microphone output mode, and a CD playback mode. A voice output unit
8
amplifies a voice signal obtained during the operational mode selected by the mode selection switch
7
, and outputs a voice in accordance with the voice signal. A control panel
9
is provided for a user to perform a switching operation on the control panel
9
. A connection of the mode selection switch
7
is switched in response to the switching operation by the user.
The tape recorder unit
3
includes a magnetic head
11
, a recording head amplifier unit
12
, a playback head amplifier unit
13
, a record/playback switch SW
1
and a record/playback switch SW
2
.
The magnetic head
11
is a recording/playback head unit which records a voice signal in the magnetic tape
2
and plays back a recorded voice signal from the magnetic tape
2
. The recording head amplifier unit
12
amplifies a voice signal to be input to the magnetic head
11
. The playback head amplifier unit
12
amplifies a playback signal output from the magnetic head
11
. The record/playback switches SW
1
and SW
2
are provided to switch a connection of internal paths when one of a playback mode and a recording mode is selected.
In the tape recorder unit
3
, the magnetic tape
2
runs in a tape running path, and at the same time, the magnetic head
11
is brought into contact with the magnetic tape
2
. The tape recorder unit
3
records a voice signal in the magnetic tape
2
by using the magnetic head
11
during the recording mode. The tape recorder unit
3
outputs a playback signal derived from a recorded voice signal of the magnetic tape
2
by using the magnetic head
11
during the playback mode.
In the tape recorder unit
3
, the magnetic head
11
has a first end connected to a movable contact of the record/playback switch SW
1
, and a second end connected to both the recording head amplifier unit
12
and a fixed contact of the record/playback switch SW
2
.
The record/playback switch SW
1
has a movable contact T
1
, a fixed contact T
2
, and a fixed contact T
3
. A connection of the movable contact T
1
of the record/playback switch SW
1
is switched to one of the two fixed contacts T
2
and T
3
by a switching operation by the user on the control panel
9
. In the record/playback switch SW
1
, the movable contact T
1
is connected to the first end of the magnetic head
11
, the fixed contact T
2
is grounded via a constant-current power supply
14
, and the fixed contact T
3
is connected to a central voltage supply line. A central voltage “½ Vcc” from the central voltage supply line is supplied to the fixed contact T
3
of the record/playback switch SW
1
. During the recording mode, the connection of the movable contact T
1
is switched to the fixed contact T
2
. During the playback mode, the connection of the movable contact T
1
is switched to the fixed contact T
3
.
The record/playback switch SW
2
has a movable contact T
11
, a fixed contact T
12
, and a fixed contact T
13
. A connection of the movable contact T
11
of the record/playback switch SW
2
is switched to one of the two fixed contacts T
12
and T
13
by a switching operation by the user on the control panel
9
. In the record/playback switch SW
2
, the movable contact T
11
is connected to an input of the playback head amplifier unit
13
, the fixed contact T
12
is connected to the central voltage supply line, and the fixed contact T
13
is connected to the second end of the magnetic head
11
. The central voltage “½ Vcc” from the central voltage supply line is supplied to the fixed contact T
12
of the record/playback switch SW
2
. During the recording mode, the connection of the movable contact T
11
is switched to the fixed contact T
12
. During the playback mode, the connection of the movable contact T
11
is switched to the fixed contact T
13
.
The recording head amplifier unit
12
includes an operational amplifier
21
and a plurality of resistors R
1
through R
6
. The recording head amplifier unit
12
constitutes a non-inverting amplifier. The recording head amplifier unit
12
amplifies a voice signal output from one of the CD playback unit
4
, the radio unit
5
and the microphone unit
6
, and supplies the amplified voice signal to the magnetic head
11
.
The playback head amplifier unit
13
includes an operational amplifier
31
, a plurality of resistors R
11
through R
13
, a capacitor C
1
, and a capacitor C
2
. The playback head amplifier unit
13
constitutes a high-gain amplifier. During the playback mode, the magnetic head
11
is connected through the record/playback switch SW
2
to a non-inverting input of the operational amplifier
31
in the playback head amplifier unit
13
. A playback signal from the magnetic head
11
is amplified by the operational amplifier
31
, and the amplified playback signal is output to the mode selection switch
7
. During the recording mode, the central voltage “½ Vcc” from the central voltage supply line is supplied through the record/playback switch SW
2
to the non-inverting input of the operational amplifier
31
. The input of the playback head amplifier unit
13
is set in the muted condition.
It is necessary for the playback head amplifier unit
13
to amplify a small playback signal from the magnetic head
11
. The playback head amplifier unit
13
provides a high gain, for example, 55 dB at 50 Hz, 39 dB at 1 kHz, 34 dB at 10 kHz.
The mode selection switch
7
includes a movable contact T
21
and a plurality of fixed contacts T
22
through T
25
. In the mode selection switch
7
, a connection of the movable contact T
21
is switched to one
Furuya Misao
Takamatsu Seiji
Kim W. Chris
Ladas & Parry
Mitsumi Electric Co. Ltd.
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