JPH0755731Y2 - Radio signal playback device with radio - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an audio signal reproducing apparatus with a radio such as a cassette player with a radio, and in particular, a technique of a circuit for switching between radio output reproduction and another audio output reproduction. Regarding

[Outline of device]

This device has a built-in preamplifier and power amplifier, and powers on these preamplifier and power amplifier separately.
By using an IC having a control unit for turning off, it is possible to favorably switch between radio output reproduction and another audio output reproduction from the reproduction device.

[Conventional technology]

Conventionally, for example, in a so-called cassette player with a radio, a circuit as shown in FIGS. 3 and 4 is known as a circuit for switching between the radio output and the reproduction audio signal output from the cassette tape.

The example of FIG. 3 uses the two-circuit switch S ₁ as a mode changeover switch. When this switch S ₁ is changed over to the cassette player side, the switch S _{1 in} FIG.
_{When 1-1} and S _1-2 are switched to contact TC side and switched to radio receiver side, switches S _1-1 and S _1-2 are contact TR
It will switch to the side.

Further, S ₂ is a leaf switch, which is turned on when the play button of the cassette player is pressed.

Also, (1) is a DC power supply, (2) is a radio receiver section,
(3) is a cassette player driving motor, (4) is a magnetic head, (5) is a reproduction equalizer amplifier, (6) is an audio amplifier, and (7) is headphones.

To explain the operation of the circuit of FIG. 3, the switch
In the case where S ₁ is switched to the TC side, the power supply when the leaf switch S ₂ is not pressed the play button is off (1)
Is not applied to any circuit part, and the device does not operate.

Then, when the play button is pressed and the leaf switch S ₂ is turned on when the switch S ₁ is switched to the TC side, power is supplied from the power supply (1) to the motor (3) and the reproduction equalizer amplifier (5). At the same time as being turned on, the audio amplifier (6) is also turned on via the switch S _1-1 . Therefore, by driving the motor (3), the cassette tape is put into a reproducing state, and the reproduced audio signal from the head (4) is supplied to the audio amplifier (6) through the reproducing equalizer amplifier (5) and the adding circuit (8). The reproduced sound is heard through the headphones (7). That is, the reproduction output mode of the cassette tape player is set.

Next, when switch S ₁ is switched to the TR side, the switch
The radio receiver section (2) is supplied with power via the switch S _1-2 and the audio amplifier (6) is supplied with power via the switch S _1-1 , regardless of whether S ₂ is on or off.
The audio output from the radio receiver section (2) can be heard through the headphones (7). That is, the reproduction mode of the radio receiver output is set.

At this time, a pause signal is given to the motor (3) from the power source (1) through the switches S _1-1 and S _1-2 , and the motor (3)
Is not rotated, so in this radio output reproduction mode, even if the play button is pressed and the leaf switch S ₂ is turned on and the motor (3) is powered on, this motor (3) does not rotate, The cassette tape is not in the playback state.

As described above, in the example of FIG. 3, the radio output reproduction mode and the tape reproduction output mode are switched by the two-circuit switch S ₁ and the leaf switch S ₂ .

Next, the example of FIG. 4 will be explained. In this example, a mode switch is performed by one circuit switch S ₃ and a leaf switch S ₂ which is turned on by pressing a play button and two transistors Q ₁ and Q _2. Therefore, the same reference numerals are given to the portions corresponding to the example of FIG.

To explain the operation in this example, switch S ₃ is
In the case where the switch is switched to the side, when the play button is not yet pressed and the switch S ₂ is off, the power is not supplied to any circuit section, and the device is in the inoperative state.

Also, when the switch S ₃ is switched to the TC side, the leaf switch S ₂ is pressed the play button is ON, the motor (3) via the switch S ₂ and the reproduction equalizer amplifier (5) The audio amplifier (6) is turned on, and the reproduction output of the cassette tape becomes audible through the headphones (7).

Next, when the mode switch S ₃ is switched to the TR side, power is supplied to the audio amplifier (6) and the motor (3) regardless of whether the leaf switch S ₂ is on or off. Also, at this time, the base of the transistor Q ₂ becomes the power supply voltage, so that the transistor Q ₂ is turned on, and thus the transistor Q ₁ is also turned on, and power is supplied to the radio receiver section (2) through the transistor Q _1. At the same time, a pause signal is supplied to the motor (3). Therefore, the motor (3) does not rotate even though the power is on, and the output of the radio receiver can be heard by the headphones.

[Problems to be solved by the invention]

In the case of the switching system of the example of FIG. 3, since two circuit switches are used, the cost of parts is high and the circuit becomes complicated.

Further, the switching system of the example of FIG. 4 requires two transistors even if one circuit switch is used, which increases the cost.

Also, in the case of radio output in both the example of FIG. 3 and the example of FIG. 4,
Since the reproduction equalizer amplifier is in the operating state, its output impedance is low, which causes a drawback that the output level becomes low.

Also, in both cases, a pause signal for stopping the motor must be supplied to this motor at the time of radio output.

Further, in the case of the example of FIG. 4, since the power of the radio receiver section (2) is supplied through the transistor Q ₁ , the power is reduced by the collector-emitter saturation voltage of the transistor Q ₁ and the power is reduced accordingly. Only that means the battery life is short.

This invention is intended to eliminate the above drawbacks.

[Means for solving problems]

In this invention, a radio receiver section (2), a reproducing apparatus section that is driven by a motor (3) to obtain another audio output, and a preamplifier section (the other audio output from the reproducing apparatus section are supplied. 11) and this preamp section (1
The power amplifier section (12) to which the output of 1) and the output of the radio receiver section (2) are supplied, and the preamplifier section (11) and the power amplifier section (12) are connected to the first and second mode signals P ₁
And control unit for each separate power-on and off based on the P ₂ (14) and an IC which is built (10), when the radio output first contact, during the further audio output playback second A first switch S ₄ which is switched to the contact of
A second switch S ₂ that is turned on when reproduction is started in the reproduction device section and a power supply circuit (1) are provided, and the power supply voltage from the power supply circuit (1) is supplied to the IC (10). It is supplied to the radio receiver section (2) via the first contact of the first switch S ₄ and further to the IC (10) as the first mode signal P ₂ , and the power supply voltage is the first switch S ₄ To the IC (10) as the second mode signal P ₁ via the second switch S ₂ via the second contact of

[Action]

The states of the first and second mode signals P ₂ and P ₁ , which are changed by switching the first switch S ₄ , are the control unit (1
It is determined in 4), and based on this, the power on / off of the preamplifier section (11) and the power amplifier section (12) is controlled, and the radio output reproduction and another audio reproduction are switched.

〔Example〕

FIG. 1 shows an example in which the present invention is applied to a cassette player with a radio, and the same parts as those in the conventional example are designated by the same reference numerals.

In this example, a switch S ₄ with one circuit and two contacts is provided as a mode selector switch, and the preamplifier (1
1), a power amplifier section (12), a common section (13) including a bias circuit, and a control section (independently powering on / off each of these amplifier sections (11), (12), and common section (13). An IC (10) with a built-in 14) is provided.

The tape reproduction output from the head (4) is input to the preamplifier section (11) of the IC (10), and a reproduction equalizer element such as a capacitor and a resistor is connected to the IC (10) for the preamplifier section (11). Connect externally to form a playback equalizer amplifier. The output of the reproduction equalizer amplifier is input to the power amplifier section (12) via the volume (15).

Also, the output of the radio receiver section (2) is the volume (15)
Is supplied to the power amplifier section (12) via.

In this example, the common part (1
Bias voltage from 3) is given.

Moreover, although resistors for level adjustment are provided on both the output side of the preamplifier section (11) and the output side of the radio receiver section (2), only one of them may be provided.

Then, the DC voltage of the power source (1) is supplied to the IC (10) and also applied to the movable contact of the mode switch S ₄ . Further, the TC side contact of the mode switch S ₄ is supplied to the power supply terminal of the motor (3) via the leaf switch S ₂ , and
The state of the voltage obtained at the connection point between the leaf switch S ₂ and the motor (3) is supplied to the control unit (14) of the IC (10) as the second mode signal P ₁ . Further, the TR side contact of the mode switch S ₄ is connected to the power line of the radio receiver section (2), and the state of the voltage obtained at this TR side contact is used as the first mode signal P ₂ for the IC (10). Is supplied to the control section (14) of.

The operation of the circuit of FIG. 1 will be described below.

When the mode switch S ₄ is switched to the TC contact and the play button is not pressed and the leaf switch S ₂ is open, the motor (3) is off and both signals P ₁ and P ₂ are low. IC because it is a level
(10) is turned off, so the preamplifier section (1
1), the power amplifier section (12) and the common section (13) are all turned off, and the radio receiver section (2) is also turned off, so the apparatus is off as a whole and nothing is operated.

Next, when the play button is pressed and the leaf switch S ₂ is short-circuited while the switch S ₄ is switched to the TC side contact, the motor (3) is powered on and the second mode signal P ₁ Is high level, and the first mode signal P ₂ remains low level, the preamplifier section (11), the power amplifier section (12) and the common section (13) are powered on by the control section (14), The tape reproduction output from the head (4) can be heard by the headphones (7) through the equalizer amplifier including the preamplifier section (11) and the power amplifier section (12). That is, the cassette reproduction mode is set.

Further, when the switch S ₄ is switched to the TR side contact, the radio receiver unit (2) is powered on and the _second switch is turned on regardless of whether the leaf switch S ₂ is turned on or off.
Mode signal P ₁ of the low level and the first mode signal P ₂ of the high level, the control unit (14) turns off the preamplifier unit (11) and turns on the power amplifier unit (12).
Since the common part (13) is turned on, the radio receiver part (2)
The output of the headphone (7) via the power amplifier (12)
Is supplied to the radio receiver output playback mode.

FIG. 2 is a mode table for explaining the state of each part in each of the above mode states.

In addition, this invention is not limited to a cassette player with a radio,
For example, it can be applied to a compact disc player with a radio and other audio signal reproducing devices with a radio.

[Effect of device]

According to the circuit of the present invention described above, the mode switch is 1
Since it is a circuit switch and does not require an external transistor, the cost is low and the configuration is simple.

Further, since the preamplifier (reproduction equalizer amplifier) is off during radio output, its output impedance is high and the output level does not decrease unlike the conventional example.

Further, since the motor power supply is off during radio output, it is not necessary to supply a pause signal to this motor as in the conventional case, and the structure is simplified accordingly.

Further, since no transistor is used as in the example of FIG. 4, the power supply of the radio receiver does not decrease and the battery life does not become short.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, FIG. 2 is a diagram for explaining a mode state, and FIGS. 3 and 4 are block diagrams of an example of a conventional cassette tape player with radio. (1) is a power source, (2) is a radio receiver section, (3) is a motor, (4) is a reproducing magnetic head, (10) is an IC, (11) is a preamplifier section, and (12) is a power amplifier section. , (14) is a control unit, S ₄ is a mode switch, and S ₂ is a leaf switch.

Claims (1)

[Scope of utility model registration request] 1. A radio receiver section, (b) a reproducing apparatus section which is driven by a motor to obtain another audio output, and (c) another audio output from the reproducing apparatus section. The preamplifier section, the power amplifier section to which the output of the preamplifier section and the output of the radio receiver section are supplied, and the preamplifier section and the power amplifier are separately turned on based on the first and second mode signals. An IC having a built-in control unit for turning it off, (d) a first switch that is switched to the first contact when the radio output is made, and to a second contact when the other audio output is reproduced, (e) It has a second switch that is turned on when reproduction is started in the reproduction device section, and (f) a power supply circuit, and (g) a power supply voltage from the power supply circuit is supplied to the IC and The radio receiver unit via a first contact of the first switch, is further supplied to the IC as the first mode signal, (h) Further, the power supply voltage and the second of said first switch
Is supplied to the motor and the IC as the second mode signal through the second switch through the contact of the first switch, and (i) the first switch which is changed by switching the first switch.
And, the state of the second mode signal is detected by the control unit of the IC, and on / off of the power supply to the preamplifier unit and the power amplifier unit is controlled based on this, and the radio output reproduction and the different audio reproduction are An audio signal reproducing device with a radio adapted to be switched.