JP2002367270A - Reset circuit in car audio device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reset circuit of a microcomputer for control, which can be operated for reset by a user in a car audio device. SOLUTION: A microcomputer 7 controlling reproduction mechanism is provided with a reset input terminal (RESET) and an eject-input terminal (EJECT) inputting an on-off signal of an eject-key 5, an output Vout of a reset IC 3 is connected to the RESET, normally, it is in a high level of a power source 5 V. A reset circuit 10 cuts off supply of a power source VDD of the reset circuit 10 when the eject-key 5 is pressed for 2-3 seconds or pressed repeatedly (pressed several number of times for 2-3 seconds), when the power source voltage VDD becomes a threshold voltage (2.5 V) of the reset IC 3 by discharge of a capacitor C2, the output voltage Vout is made to a low level, and the microcomputer 7 is reset (initialized).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact disk (hereinafter abbreviated as CD), a mini disk (hereinafter M).
Also abbreviated as D. The present invention relates to a reset circuit for a car audio device provided with a reproducing device for an external recording medium, such as an external recording medium.

[0002]

2. Description of the Related Art Conventionally, amplifiers, tuners, CDs and MDs have been used.
And the like, a playback device for an external recording medium or the like is collectively controlled by one control microcomputer built in the main body. This method is centralized control by one microcomputer, so the cost merit is great, but recently the audio system itself has become too large and the control functions are quite large, so it is difficult to control with one microcomputer. The burden is too high.

In addition, each time a new model is developed, the control portion of the external recording medium is also newly designed, which increases the time and cost required for development.

Therefore, in the field of car audio equipment, development is proceeding in the direction of blocking, and a microcomputer for control is divided into one for controlling a mechanical system and one for controlling a reproducing system instead of one microcomputer. There are many cases to be configured.

[0005]

[0006] Unlike audio equipment for indoor use, car audio equipment has an extremely severe use environment. That is, since there is an environment in which a lot of surge noise due to an ignition, a relay, a motor, static electricity or the like is likely to occur, there is a high possibility that the microcomputer malfunctions. Once a malfunction occurs, it is necessary to cut off the power supply of the microcomputer. However, unlike ordinary home appliances, once a car audio device is turned on, the microcomputer is not turned off except when the battery of the car is replaced. Therefore, after an external recording medium such as a cassette tape, a CD, or an MD is inserted into a playback device of a car audio device, if the microcomputer malfunctions, initialization cannot be performed.
An external recording medium such as D or MD may not be able to be removed even if the eject key is pressed, which may cause a problem.

A microcomputer for control in an audio device is provided with a reset input terminal which is initialized by switching an input signal from high to low, and a reset IC for inputting a reset signal to the reset input terminal.
Are connected to a microcomputer power supply together with an appropriate time constant circuit. This reset IC keeps the reset input terminal low until the voltage reaches a predetermined level when the power is turned on, for example, to avoid an uncertain level state in the microcomputer when the power is turned on / off. For example, the input voltage of the reset IC (power supply voltage of the microcomputer) is equal to the threshold voltage 2.
The output switches between high and low at 5V.

When the above-described problem occurs, the microcomputer can be initialized and returned to a normal state by switching the reset input terminal of the microcomputer from high to low. Even if a reset key for generating the reset signal is provided on the operation panel of the car audio device, an erroneous operation by the user is likely to occur.

Conventionally, it has not been assumed to cope with a situation in which an external recording medium such as a CD or MD cannot be taken out due to a malfunction of the microcomputer. Naturally, an operation button called a reset key is provided on the operation panel. Absent. If the user falls into the above situation, there is no other way than to send the manufacturer a repair.

According to the present invention, in a car audio device, when a situation in which an external recording medium cannot be taken out due to a malfunction of a microcomputer that controls a reproducing mechanism,
It is an object of the present invention to provide a reset circuit in a car audio device in which the microcomputer can be initialized by the user himself so that the microcomputer can be normally restored.

[0010]

According to the present invention, there is provided a microcomputer for controlling a reproducing mechanism of an external recording medium in a car audio apparatus having a reproducing apparatus of the external recording medium. A reset circuit for generating a reset signal for executing the initialization of the microcomputer, and outputting a reset signal for initialization of the microcomputer when an eject key for ejecting the external recording medium from the playback device is kept pressed for a predetermined time. And a reset circuit in the car audio device, wherein the reset signal is input to a reset input terminal of the microcomputer. (2) A reset circuit for generating a reset signal for executing initialization of a microcomputer for controlling a reproduction mechanism of the external recording medium in a car audio device including a reproduction device of the external recording medium, wherein the reset circuit includes: Means for outputting a reset signal for initializing the microcomputer when the eject key for ejecting the recording medium from the playback device is continuously pressed a plurality of times at intervals of a predetermined time or less. Provided is a reset circuit in a car audio device, which is configured to be inputted to a reset input terminal of a computer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reset circuit in a car audio device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an example of a circuit diagram of a reset circuit according to claims 1 and 2 of the present invention.

FIG. 2 shows (a) the reset input terminal voltage (Vout) of the microcomputer, (b) the power supply voltage V _{DD of} the reset IC, and (c) the eject key when the eject key of the reset circuit is pressed. FIG. 9 is a waveform chart of the base potential of the transistor Q1 when the key is repeatedly hit.

In FIG. 1, a microcomputer 7 for controlling the reproducing mechanism 1 has a reset input terminal (RESET).
And an eject input terminal (EJECT) for inputting an on / off signal of the eject key 5. The output Vout of the reset IC 3 is connected to RESET, and is normally at the high level of the power supply 5V.

The reset circuit 10 of the present invention is a circuit portion surrounded by a broken line, and holds when the eject key 5 is pressed, and turns off the power of the reset circuit 10 when the eject key 5 is pressed. Voltage (eg, 2.5
V), the output voltage Vout goes low, and the microcomputer 7 is reset (initialized).

A resistor R1 (150 kΩ) in the circuit diagram is a bias resistor of the transistor Q1 and a capacitor C1 (1 kΩ).
0 μF) forms a time constant circuit. This capacitor C
1 holds the low level for 0.5 to 1 second when the eject key 5 is pressed. The transistor Q1 (for example, 2SC
2712), Q2 (for example, RN2404) is reset I
C3 (for example, S80825) power supply (Pin 2 (+),
Turn on / off the 3rd pin (-)). Resistance R3 (100
kΩ) is a resistance for increasing the ON voltage of the transistor Q1. The capacitor C2 (10 μF) inserted in parallel between the power supplies of the reset IC 3 forms a time constant circuit with the resistor R2 (470 kΩ), and holds the power supply voltage of the reset IC 3 for 2 to 3 seconds. The discharge time is set by the value of the resistor R2.
The output (the first pin) Vout of the reset IC 3 is turned on at the threshold voltage. The resistor R4 (1 kΩ) saves a sudden discharge when the eject key 5 is pressed. Diode D1 is a pull-up resistor R6 of eject key 5.
(47 kΩ).

The eject key 5 is installed on the front panel of the car audio equipment, and has an eject input terminal (EJECT) of the microcomputer 7 and a resistor R.
4. It is connected to the base of the transistor Q1 via the diode D1.

In normal operation, the eject key 5
Is pressed once, the base of the transistor Q1 is discharged via the resistor R4 and the diode D1, and the transistors Q1 and Q2 are turned off for a short time. At this time, since the capacitor C2 is connected to the reset IC 3 and the power supply voltage _VDD is held, there is no reset.

Next, when an abnormality occurs in the microcomputer 7 and the external recording medium material does not operate, even if the user presses the eject key 5 to remove the external recording medium material, the microcomputer 7 in which the abnormality has occurred Cannot be detected, and discharge becomes impossible.

At this time, if the eject key 5 does not work as a human psychology, the eject key 5 is repeated many times.
, Or a long press of the eject key 5 (long press).

If the eject key 5 is pressed for a long time, the transistor Q is connected via the resistor R4 and the diode D1.
1 is discharged, and the transistors Q1 and Q2 are turned off. When the eject key 5 is kept depressed, it remains off, so that the capacitor C2 continues to be discharged, the power supply voltage VDD of the reset IC 3 gradually decreases, and drops to the threshold voltage of the reset IC 3 (for example, 2.5 V). Then, the reset IC 3 operates, Vout goes low, and the microcomputer 7 is reset.
When the eject key 5 is turned off, the microcomputer 7 operates normally, and the eject / key 5 can be normally received. In addition,
It is preferable that the time of the long press until the above-mentioned reset or suspension is performed is 2-3 seconds.

Next, a description will be given of the operation when the reset is suspended by repeatedly hitting the eject key 5. When the eject key 5 is repeatedly turned on / off within a predetermined time interval, the base of the transistor Q1 of the reset circuit 10 is reset. Discharges immediately when the eject key 5 is turned on, but when it is turned off, it takes time to charge due to the time constant of the capacitor C1 and the resistor R1, and the transistor Q1 does not turn on immediately (the eject key 5). 5 is on). Therefore, the off state of the transistors Q1 and Q2 is maintained while the eject key 5 is repeatedly struck, and the power supply voltage V _DD of the reset IC 3 is gradually lowered to be reset.

FIG. 2C shows the waveform of the base voltage of the transistor Q1 when the eject key 5 is repeatedly struck five times at intervals of about 0.6 seconds.
It does not stand up enough to turn on 1 and remains off,
As a result, since the transistor Q2 is turned off, the voltage gradually decreases as shown by the waveform of the power supply voltage _VDD of the reset IC 3 in FIG. 2B, and after a few seconds, Vou as shown in FIG.
t (= the RESET input voltage) goes low, causing a reset. The interval between successive hits is set to 0.8 seconds, for example, so that the transistor Q1 is not turned on. The reset is performed by performing several hits, preferably 2 to 5 times, within a time interval of 0.8 seconds or less. The time constant between the capacitor C1 and the resistor R1 is set as described above.

The reset circuit 10 shown in FIG. 1 is a circuit in which the reset is performed by both the long press and the continuous hit of the eject key 5, but it is needless to say that only one of the reset circuits may be used. The reset circuit 10 holds the off state of the transistor Q1 with the capacitor C1 and resets the reset IC.
3 is an embodiment of a means for setting the output Vout to low, but as another means for realizing a reset circuit, a count circuit is provided, and the eject key 5 is set within a predetermined time set to about 2 to 3 seconds. The number of presses is counted.
Means for resetting by setting T) low may be used.

The essential point of the reset circuit according to the present invention is that the reset input of the microcomputer 7 is performed when a predetermined condition which is achieved by a long press operation or a continuous hit operation of the eject key 5 which is not normally performed by the user under normal conditions is satisfied. The point is that the level of the terminal (RESET) is switched from high to low to perform reset (initialization).

If the above mechanism is described metaphorically, when buying canned juice from a vending machine, if a coin is inserted and the button is pressed and the canned juice does not come out, as a human psychology, the button is pressed many times. They often push or press for a long time. If you still do not come out, you push the coin return lever or hit the vending machine.

The same applies to a car audio device. When a CD or MD does not appear even when the eject key 5 (EJECT KEY) is pressed, the eject key is repeatedly pressed or long-pressed.

The present invention utilizes this human psychology, and when an abnormality occurs in a microcomputer for controlling a reproduction mechanism of an external recording medium, the user himself or herself consciously or unconsciously presses and holds the eject key 5 for a long time. The reset signal (Vout) is generated by repeated tapping, the microcomputer 7 for controlling the reproducing mechanism is initialized, the normal state is restored, and the eject is returned to the normal state.

[0029]

Since the reset circuit in the car audio device according to the present invention is configured as described above, it has the following effects.

(1) If the microcomputer needs to be reset due to an abnormality, it is possible to reset the microcomputer and return to normal by holding down the eject key or repeatedly hitting the power without turning off the power. .

(2) The external recording medium is not ejected even when the eject key is pressed. When the microcomputer malfunctions, the user consciously or unconsciously presses the eject key for a long time or repeatedly presses the eject key to reset the microcomputer. A reset has been made and it can be returned to normal.

[0032]

[Brief description of the drawings]

FIG. 1 is an example of a circuit diagram of a reset circuit according to claims 1 and 2 of the present invention.

FIG. 2 shows (a) a voltage waveform of a reset input terminal (RESET) of a microcomputer, (b) a voltage waveform of a power supply voltage V _DD of a reset IC, when the eject key of the reset circuit is long-pressed or hit repeatedly. (C) is a waveform chart of each base potential of the transistor Q1 when the eject key is repeatedly struck.

[Explanation of symbols]

3 Reset IC 5 Eject key 7 Microcomputer 10 Reset circuit _VDD Power supply voltage of reset IC Vout Output of reset IC RESET Reset input terminal EJECT Eject input terminal

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Rim Bunky 1-1-1 Sakata, Oizumi-cho, Ouraku-gun, Gunma Prefecture FMS Audio Sendy Lian Bahad F-term (reference) 5B054 AA13 BB08 CC01 DD03 DD15 5J055 AX37 AX60 AX66 BX42 CX27 CX28 DX04 DX05 DX55 DX83 EX06 EX22 EY01 EY10 EY17 EZ00 EZ39 FX12 FX17 FX27 FX36 GX01 GX04

Claims (2)

[Claims] 1. A reset circuit for generating a reset signal for executing initialization of a microcomputer for controlling a reproduction mechanism of an external recording medium in a car audio device provided with a reproducing apparatus of the external recording medium, the reset circuit comprising: Means for outputting a reset signal for initialization of the microcomputer when the eject key for ejecting the recording medium from the playback device is kept pressed for a predetermined time, and the reset signal is input to a reset input terminal of the microcomputer. A reset circuit in a car audio device characterized by the following configuration. 2. A reset circuit for generating a reset signal for executing initialization of a microcomputer for controlling a reproduction mechanism of the external recording medium in a car audio device including a reproducing apparatus of the external recording medium, wherein the reset circuit comprises: Means for outputting a reset signal for initializing the microcomputer when the eject key for ejecting the recording medium from the reproducing apparatus is continuously pressed a plurality of times at an interval of a predetermined time or less. A reset circuit in a car audio device, wherein the reset circuit is inputted to a reset input terminal of a computer.