JP2001339249A - Electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device which has a mute circuit and a power-ON reset circuit and enables muting and the resetting of a microcomputer with simple constitution. SOLUTION: When the power source is turned on and a power supply circuit 3 supplies electric power to a microcomputer power generating circuit 7, a driving power source generating circuit 4, and the mute circuit 5, the mute circuit 5 mutes an audio signal and the reset circuit 101 sends a reset signal to the microcomputer 9 according to a reset signal sending-out instruction from the mute circuit 5, thereby resetting the microcomputer 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic device, and more particularly, to an electronic device having a mute circuit and a power-on reset circuit.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a main part of an electronic device including a mute circuit and a power-on reset circuit.

The electronic device 1 includes a power supply circuit 3, a drive power supply generation circuit 4, an audio circuit 5, a mute circuit 6, a microcomputer power supply generation circuit 7, a power-on reset circuit 8, and a microcomputer 9.

The power supply circuit 3 supplies power for driving the device 1. The drive power supply generation circuit 4 generates a power supply for driving the audio circuit 5 and the like built in the electronic device 1 from the power supply supplied from the power supply circuit 3.
The audio circuit 5 performs various audio processing such as equalizing on the audio signal and outputs the audio signal.

[0005] The output audio signal of the audio circuit 5 is output via a mute circuit 6. The mute circuit 6 detects the supply and disconnection of power from the power supply circuit 3 and mutes the output audio signal from the audio circuit 5.

The microcomputer power generation circuit 7 generates a power supply for driving the microcomputer 9. The power generated by the microcomputer power generation circuit 7 is supplied to the power-on reset circuit 8 and the microcomputer 9. The power-on set circuit 8
The microcomputer 9 is reset according to the power supply voltage from the microcomputer power generation circuit 7. The microcomputer 9 is reset according to a reset signal from the power-on reset circuit 8. The microcomputer 9 controls the operation of the electronic device 1 according to the operation by the operator.

FIG. 5 shows a circuit configuration diagram of a main part of an example of a conventional electronic device. 4, the same components as those of FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

The driving power supply generating circuit 4 includes a diode D1,
D2, a capacitor C1, and a stabilized power supply circuit 11. The power from the power supply circuit 3 includes diodes D1 and D2.
Is rectified. The power rectified by the diodes D1 and D2 is smoothed by the capacitor C1. The power source smoothed by the capacitor C1 is a stabilized power source circuit 1
1 is supplied. The stabilized power supply circuit 11 includes a diode D
1, a power supply rectified and smoothed by D2 and a capacitor C1 is output after being stabilized at a predetermined power supply voltage. The output voltage of the stabilized power supply circuit 11 is supplied to each part of the electronic device 1 as drive power. The microcomputer power generation circuit 7 includes a diode bridge 12, a capacitor C2, and a stabilized power supply circuit 13. The diode bridge 12 performs full-wave rectification on the power from the power supply circuit 3. Diode bridge 1
The voltage rectified by 2 is smoothed by the capacitor C2. The voltage smoothed by the capacitor C2 is supplied to the stabilized power supply circuit 13. When the voltage rectified and smoothed by the diode bridge 12 and the capacitor C2 is equal to or higher than a predetermined voltage, the stabilized power supply circuit 13
When a voltage of about 5 [V] is output and the voltage rectified and smoothed by the diode bridge 12 and the capacitor C2 is equal to or lower than a predetermined voltage, the output becomes unstable.

The output voltage of the stabilized power supply circuit 13 is used as a drive voltage for the microcomputer 9 and is supplied to the power-on reset circuit 8.

The power-on reset circuit 8 includes a capacitor C3, a diode D3, resistors R4 to R6, and a transistor Q1.
Consists of When the output voltage of the stabilized power supply circuit 13 rises, the capacitor C3 is charged. Capacitor C
The current charged by 3 is supplied to the resistors R1, R2 and the base of the transistor Q1. Transistor Q1
Is turned on when a current flows through the base. When the transistor Q1 is turned on, the transistor Q1
Collector (Treset) goes low. When the charging of the capacitor C3 approaches the end, the transistor Q1
, The transistor Q1 turns off. When the transistor Q1 is turned off, the collector (Treset) of the transistor Q1 becomes high level.

The transistor Q1 is composed of an NPN transistor, the base is connected to the connection point between the resistors R1 and R2, the collector is connected to the output of the stabilized power supply circuit 13 via the resistor R3, and the emitter is grounded. You. The connection point of the resistor R1 and the resistor R2 is a base of the transistor Q1.
It turns on when the voltage is higher than the junction voltage between the emitters, and turns off when the voltage is lower.

A connection point between the collector of the transistor Q1 and the resistor R3 is used as an output terminal. Transistor Q
1 indicates that when the output of the stabilized power supply circuit 13 rises,
Turn on. The collector of the transistor Q1 is connected to the microcomputer power supply terminal Tv1 via the resistor R3 and is also supplied to the microcomputer reset terminal Treset.
Therefore, when the transistor Q1 is turned on, the microcomputer reset terminal Treset goes low. The microcomputer reset terminal Treset is connected to the reset terminal of the microcomputer 9, and the microcomputer 9 is reset when the microcomputer reset terminal Treset goes low.

The mute circuit 5 includes diodes D4 to D4.
7, Zener diode D8, PNP transistor Q
2, NPN transistor Q3, capacitors C4 to C6,
It is composed of resistors R4 to R10. The mute circuit 5 detects a voltage supplied from the power supply circuit 3 to the drive power generation circuit 4 and mutes the audio signal when the power is turned on / off.

When power is supplied from the power supply circuit 3,
While the capacitor C6 is being charged, the transistor Q2 is turned on. When the transistor Q2 is turned on, the transistor Q3 is turned on. The transistor Q3 has a collector connected to the audio signal terminal Tau and an emitter connected to the audio ground terminal Taugnd. For this reason,
When the transistor Q3 is turned on, the audio signal is changed from the audio signal terminal Tau to the audio ground terminal Tau.
The audio signal is muted by flowing to gnd.

When the power supply from the power supply circuit 3 is turned off, the capacitor C6 is discharged, so that the base-emitter voltage of the transistor Q2 becomes an on-voltage, and the transistor Q2 is turned on. When the transistor Q2 is turned on, the electric charge charged in the capacitor C5 flows to the base of the transistor Q3, and the transistor Q3
Turns on, the audio signal flows from the audio signal terminal Tau to the audio ground terminal Taugnd, and the audio signal is muted. The Zener diode D8 prevents the transistor Q2 from malfunctioning when the voltage of the power supply circuit 3 changes.

As described above, the microcomputer 9 is reset and the audio signal is muted.

In the electronic device shown in FIG. 5, the microcomputer 9 can be reset when the power is turned on, but cannot be reset when the power is turned off.

FIG. 6 shows a circuit diagram of another example of the prior art. In the figure, the same components as those of FIG.
The description is omitted.

The reset circuit 21 includes a reset IC 22,
Transistors Q11, Q12, capacitor C11, resistor R11 ~
R15.

The output of the reset IC 22 is low when the input voltage is lower than a predetermined voltage, and is high when the input voltage is higher than the predetermined voltage. Therefore, when the voltage from the microcomputer power generation circuit 7 is equal to or lower than the predetermined voltage, the output of the reset IC 22 is at a low level, and the transistor Q11 is turned off. When the transistor Q11 is off, the transistor Q12 turns on. Transistor Q
When 12 turns on, the reset terminal Treset goes to low level.

When the voltage from the microcomputer power supply generation circuit 7 exceeds a predetermined voltage, the output of the reset IC 22 goes to a high level, so that the transistor Q11 is turned on. When the transistor Q11 turns on, the transistor Q12 turns off. When the transistor Q12 turns off, the reset terminal Tre
set goes high.

[0022]

However, the conventional FIG.
The reset circuit shown in (1) supplies a reset signal when power is turned on, and cannot be reset when power is turned off.

In the reset circuit shown in FIG. 6, reset can be performed both when the power is turned on and when the power is turned off. However, since a reset IC must be used for the reset circuit, the circuit configuration becomes complicated. There was a problem that the circuit became expensive.

[0024] The present invention has been made in view of the above points, and has as its object to provide an electronic device capable of performing mute and reset of a microcomputer with a simple configuration.

[0025]

According to a first aspect of the present invention, a mute circuit detects a mute of an audio signal and outputs a reset signal when the mute of the audio signal is detected.

According to a second aspect of the present invention, a voltage detected by a first power supply stabilizing circuit for stabilizing power supplied to a circuit reset by a reset signal is detected. When the voltage is equal to or lower than the voltage, the mute circuit is controlled to mute the audio signal, and as a result, a reset signal is output.

[0027] Further, a third aspect of the present invention is to detect a voltage in a second stabilized power supply circuit for stabilizing a drive power supply to another circuit, and to detect a voltage detected by the second voltage detection means. When the voltage of the power supply stabilization circuit is lower than a predetermined voltage, the mute circuit is controlled to mute the audio signal, and as a result, to output a reset signal.

According to a fourth aspect of the present invention, there is provided a reset time control circuit for controlling a reset time by a reset signal.

According to the present invention, the mute of the audio signal by the mute circuit is detected, and when the mute of the audio signal is detected, the reset signal is output. Because there is no
The circuit configuration can be simplified.

According to the present invention, the first power supply for stabilizing the power supply to the circuit reset by the reset signal is provided.
The voltage in the power supply stabilization circuit is detected, and when the voltage of the first power supply stabilization circuit is equal to or lower than a predetermined voltage, the sound is muted and a reset signal can be output. Can be reset by the power supply voltage supplied to the circuit.

Further, according to the present invention, the voltage in the second stabilized power supply circuit for stabilizing the driving power supply to another circuit is detected, and the voltage detection result in the second voltage detecting means is used to detect the second voltage. When the voltage of the power supply stabilization circuit is equal to or lower than the predetermined voltage, the mute circuit is controlled, the audio signal is muted, and the reset signal is output. Can be applied.

Further, according to the present invention, by controlling the reset time by the reset signal, the microcomputer or the like can be reliably reset.

[0033]

FIG. 1 is a block diagram showing a first embodiment of the present invention. 4, the same components as those of FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

When the power is turned on and power is supplied from the power supply circuit 3 to the microcomputer power generation circuit 7, the drive power generation circuit 4, and the mute circuit 5, the mute circuit 5
Mutes the audio signal. Also, the mute circuit 5
When the audio signal is muted by the reset circuit 1
01 is instructed to send a reset signal. Reset circuit 10
1 transmits a reset signal to the microcomputer 9 in response to a reset signal transmission instruction from the mute circuit 5.

The mute circuit 5 is connected to the drive power supply generation circuit 4, monitors an input voltage to the drive power supply generation circuit 4, and mutes the audio signal when a voltage drop of the input voltage occurs. . At this time, the mute circuit 5 instructs the reset circuit 101 to send a reset signal. The reset circuit 101 supplies a reset signal to the microcomputer 9 to reset the microcomputer 9.

FIG. 2 shows a circuit configuration diagram of the first embodiment of the present invention. 5, the same components as those of FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the base of the reset signal transmitting transistor Q1 of the reset circuit 101 and the collector of the mute signal transmitting transistor Q2 of the mute circuit 5 are connected via the resistors R1 and R2. And the input terminal of the stabilized power supply circuit 13 constituting the microcomputer power supply generation circuit 7 are connected via a diode D11.

In this embodiment, when a power supply voltage is supplied from the power supply device 3, the transistor Q2 is turned on, a current flows to the collector of the transistor Q2, and the transistor Q3 is turned on. Mute is applied. Further, the reset signal transmitting transistor Q1 is turned on, and the microcomputer 9 is reset. The diode D11 is provided for detecting a voltage drop at the input terminal of the stabilized power supply circuit 13 constituting the microcomputer power supply generation circuit 7. The input voltage of the stabilized power supply circuit 13 constituting the microcomputer power supply generation circuit 7 drops and the capacitor C
When the voltage of the capacitor 2 becomes lower than the voltage of the capacitor C6, a current flows through the diode D11.

When a current flows through the diode D11, a base current flows through the transistor Q2, so that the transistor Q2 is turned on. As a result, the transistor Q3 is turned on to mute the audio signal. Further, a reset signal is sent out to reset the microcomputer 9.

According to the first embodiment, since the reset circuit is controlled by the mute signal of the mute circuit and the microcomputer is reset, the audio signal can be transmitted and received with the relatively simple circuit configuration regardless of whether the power is on or off. It can mute and reset the microcomputer.

FIG. 3 shows a circuit diagram of a second embodiment of the present invention. 2, the same components as those of FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

In the electronic device of this embodiment, the input terminal voltage of the stabilized power supply circuit 11 of the drive power supply generation circuit 4 is divided by the resistors R11 and R12 at the connection point between the capacitor C6 of the mute circuit 5 and the diode D11. The voltage is applied via a diode D12. According to the present embodiment, the reset can also be performed by the input voltage drop of the drive power supply generation circuit 4.

In this embodiment, a reset time control circuit 1 for adjusting (shortening) the period of the reset signal between the collector of the transistor Q1 and the reset terminal Treset is used.
02 is provided.

The reset time adjusting circuit 102 includes a capacitor C21, a resistor R21, and a diode D21, and controls the reset signal period by controlling charging and discharging of the capacitor C21 by the resistor R21 and the diode D21.

According to this embodiment, the time of the reset signal can be set short. Therefore, since the microcomputer 9 can be reset quickly, the microcomputer 9 can be started up earlier than the mute time such as at the time of rising of the current.

In the first and second embodiments, the input voltage of the stabilized power supply circuit is detected to mute and reset. However, as shown by broken lines in FIGS. The output voltage of the circuit may be detected to mute and reset.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

[0048]

As described above, according to the present invention, the muting of the audio signal by the mute circuit is detected, and when the muting of the audio signal is detected, the reset signal is output.
Since the reset signal generation circuit does not need to detect the rise or fall of the power supply, it has features such as simplification of the circuit configuration.

Further, according to the present invention, the first power source for stabilizing the power supplied to the circuit reset by the reset signal is provided.
The voltage in the power supply stabilization circuit is detected, and when the voltage of the first power supply stabilization circuit is equal to or lower than a predetermined voltage, the sound is muted and a reset signal can be output. It can be reset by the power supply voltage supplied to the circuit.

Further, according to the present invention, the voltage in the second stabilized power supply circuit for stabilizing the drive power supply to another circuit is detected, and the voltage detection result in the second voltage detection means is used to detect the second voltage. When the voltage of the power supply stabilization circuit is equal to or lower than the predetermined voltage, the mute circuit is controlled, the audio signal is muted, and the reset signal is output. It has features such as being able to apply.

Further, according to the present invention, by controlling the reset time by the reset signal, the microcomputer can be reset in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example.

FIG. 5 is a circuit configuration diagram of an example of the related art.

FIG. 6 is a circuit configuration diagram of another example of the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 electronic device 101 reset circuit 102 reset time control circuit 3 power supply device 4 drive power generation circuit 5 mute circuit 6 audio circuit 7 microcomputer power supply generation circuit 9 microcomputer

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5D020 AA01 5J055 AX44 AX57 AX58 AX65 BX41 BX42 CX26 DX04 DX55 EX22 EX24 EY01 EY10 EY12 EY17 EZ00 EZ01 EZ15 EZ39 FX05 FX18 FX31 GX01 GX02 5J092 HA20 CA20 HA29 HA36 KA00 KA42 KA51 MA09 MA20 SA05

Claims (4)

[Claims] 1. An electronic device having a mute circuit for muting an audio signal when power is turned on and off, wherein: a mute detecting means for detecting muting of the audio signal by the mute circuit; An electronic device, comprising: a reset signal generation circuit that outputs a reset signal when a mute is detected. 2. A first power supply stabilization circuit for stabilizing power supplied to a circuit reset by the reset signal, and a first voltage detection means for detecting a voltage in the first power supply stabilization circuit. Wherein the mute circuit mutes the audio signal when the voltage of the first power supply stabilization circuit is equal to or lower than a predetermined voltage as a result of the detection by the first voltage detection means. The electronic device according to claim 1. 3. A second circuit for stabilizing a drive power supply to another circuit.
And a second voltage detection means for detecting a voltage in the second power supply stabilization circuit, wherein the mute circuit has a voltage detection result in the second voltage detection means, 3. The electronic device according to claim 1, wherein the audio signal is muted when a voltage of the second power supply stabilization circuit is equal to or lower than a predetermined voltage. 4. The electronic device according to claim 1, further comprising a reset time control circuit for controlling a reset time by said reset signal.