JP2819504B2 - Operation prohibition device for in-vehicle audio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle audio device,
After the audio equipment is stolen from the automobile, the audio equipment is made inoperable to prevent theft.

[0002]

2. Description of the Related Art Such a conventional anti-theft device pays attention to disconnection between an audio device and a battery of an automobile when the device is stolen. An apparatus for disabling audio equipment has been proposed. As a method of canceling the inoperable state, a method of inputting a predetermined recitation code is referred to Japanese Patent Publication No. 3-46897 by the present applicant. Japanese Patent Application Laid-Open No. 60-138645 is referred to as a device in which this reciting code can be arbitrarily set by an operator.

[0003]

However, in any of the above-mentioned conventional examples, when the battery of the automobile is replaced, the acoustic device is temporarily disconnected from the battery. This is the same as a stolen state for audio equipment. When inspecting and servicing a car, use a battery to prevent electric shock and short circuit.
It is common practice to remove these terminals. In this case as well, the audio device is similarly stolen, and the audio device becomes inoperable even if the battery is connected to the audio device.

[0004]

A first and a second power supply line for supplying power from a battery to an on-vehicle audio device by dividing a power supply line from a battery not through an accessory switch of a vehicle into at least two systems. ,
A power cutoff detecting means for detecting that the first and second power supply lines are disconnected from each other; and a power cutoff detecting means.
After the connection of the first and second power supply lines is restored
The control unit also makes the in-vehicle audio device inoperable .

[0005]

The in-vehicle audio equipment is made inoperable in response to the power cutoff detecting means.

[0006]

FIG. 1 is a circuit diagram of an embodiment in which the present invention is incorporated into a tape recorder 10 with a radio mounted on a vehicle. The power supply from the battery 1 mounted on the vehicle is branched off by the connector 2 which is arranged at a position which cannot be normally touched, such as the inside of the dashboard of the vehicle.
It is connected to the terminal 4 of the connector 3 by a connection cord 14 which is a first power supply line, and to the terminal 5 of the connector 3 by a connection cord 15 which is a second power supply line . The power supply from the battery 1 is connected to the terminal 6 of the connector 3 via an accessory (ACC) switch 11 that is linked to turning on and off a key of the vehicle.

A terminal 7 of the connector 3 connects the radio antenna 12 of the automobile to the tape recorder 10, and a terminal 8 connects the ground of the automobile to the tape recorder 10. It is for connecting. Thus, the tape recorder 10 is connected to the battery 1 directly through the terminals 4 and 5 and through the ACC switch 11 through the terminal 6.

The terminal 4 of the connector 3 is a tape recorder 10
Is connected to one end of the coil 20 disposed inside the transistor and is connected to the emitter of the transistor 23. The terminal 5 is connected to the base of the transistor 23. Therefore, in a normal state, the potential difference between the base emitter of the transistor 23 is zero, and the transistor 23 is in a cut-off state. The other end of the coil 20 is connected to the other end of the capacitor 21 whose one end is connected to the ground, and unnecessary noise that enters the tape recorder 10 through the power supply line by the coil 20 and the capacitor 21. Construct a filter that blocks components.

The power obtained through this filter is supplied to the tuner section 63 and the first amplifier section for supplying power to the tuner section 63 and the amplifier section, which require a power source having particularly low noise.
Is supplied to each circuit as the power supply line B1. In addition, motors that are not easily affected by noise mixed into the power supply line
The second power supply line B2 is obtained from the connection point between the terminal 5 of the connector 3 and the transistor 23 in order to supply power to the mechanism unit 62 such as the above. This connection point is connected to the ground via the resistor 13.

The anode of the diode 24 is connected to the other end of the coil 20, and its cathode is connected to the other end of the capacitor 25 whose one end is connected to the ground. The cathode of diode 24 is an IC protector (hereinafter referred to as I).
CP 26). Where I
The CP 26 is an overcurrent protection element having a characteristic of interrupting a circuit at high speed, and has the same function as a normal fuse.

For example, reference is made to the product name ICP-F10 sold by ROHM Co., Ltd., which is very similar in appearance to a semiconductor device such as a normal transistor. By arranging the ICP 26 in series with a required circuit, when a current flows over a predetermined current,
P26 has a function of irreversibly interrupting this circuit.
The other end of the ICP 26 is connected to a theft detection terminal 41 of the microcomputer 40 which will be described later.

Here, the microcomputer 40 is in normal operation.
Control the operation of the tape recorder 10,
It controls the mechanism section 62, tuner section 63, and the like of the tape recorder 10 according to commands from an operation section 60 including various operation switches. Also, when the theft
To control the tape recorder 10 to be inoperable
Functions as a unit.

The base of transistor 27 is connected to the collector of transistor 23, and the collector is connected to the base of transistor 28. The collector of the transistor 28 is connected to the ground, and the emitter is connected to the other end of the ICP 26. The transistor 29 has its base connected to an alarm set terminal 42 of the microcomputer 40 described later, its collector connected to the emitter of the transistor 27, and its emitter connected to ground. The alarm set terminal 42 is set to the "L" level when the microcomputer 40 is initialized.

The base of the transistor 30 is connected to the other end of the ICP 26, the emitter is connected to the ground, and the collector is supplied to the tape recorder 10 via the ACC switch 11 of the automobile and the terminal 6 of the connector 3. It is connected to the power supply line ACC. The collector is connected to the base of the transistor 31 whose emitter is connected to the ground. The collector of the transistor 31 has its anode connected to the power supply line B1, is connected to the cathode of the light emitting die O over leads 32 disposed on the front panel of the tape recorder 10.
The cathode is also connected to the collector of a transistor 33 whose emitter is connected to ground.

The alarm set terminal 42 of the microcomputer 40 is connected to the oscillator 34 which outputs pulses at predetermined intervals. The output of the oscillator 34 is a transistor 3
3 base.

Here, the microcomputer 40 can take the anti-theft mode by a required operation key. The anti-theft mode includes, for example, a fast-forward mode (FF) key and a rewind mode (R) provided on the front panel of the tape recorder 10.
EW) After double pressing of the key, ACC switch 1 of the car
It is obtained by turning 1 off. In this state,
The microcomputer 40 sets its alarm set terminal 42 to "H". The microcomputer detects the voltage level of the theft detection terminal 41 every time the ACC switch 11 of the automobile is turned on.

In the above configuration, the tape recorder 10
Will be described with reference to FIG. 2 which shows an operation flowchart of the microcomputer 40. In the normal connection state shown in FIG. 1, the ACC switch 11 is turned off after the FF key and the REW key are double-pressed (5).
1, 52), the tape recorder 10 enters the anti-theft mode, and the alarm set terminal 42 of the microcomputer 40 becomes "H" (53).

In this anti-theft mode, the transistor 23 is off because there is no potential difference between the base emitters, so that the transistors 27, 28, 31 are off and the transistors 29, 30 are on. Further, the oscillator 34 outputs a pulse having a constant period according to the "H" state of the alarm set terminal 42. By turning on and off the transistor 33 in synchronization with this, the light emitting diode 32 is turned on.
Blinks, appealing to the burglar through the window of the car that the tape recorder 10 is currently in the anti-theft mode.

As a result, a stolen person who knows from experience that such a tape recorder cannot be used even if it is stolen will lose his will to steal such a tape recorder. It is possible to prevent theft.

The following describes a case where the tape recorder 10 is stolen while the light emitting diode 32 is blinking. In this case, the burglar intrudes into the automobile in some way, and generally removes the tape recorder 10 attached to the automobile with screws, nuts, etc. from the automobile, and then connects the automobile to the tape recorder. An attempt is made to remove the connector 3 connecting the cable 10 and the connection cords 14 and 15.

When the connector 3 is disconnected, the connection between the base and the emitter of the transistor 23 via the connector 2 is disconnected. Therefore, the base of the transistor 23 is connected to the resistor 13
It becomes a ground level via a transistor 23 is co
It is turned on by the current from the capacitor 21 . Here, since the transistor 29 has already been turned on, the transistor 27 is also turned on.

When the transistors 27 and 29 are turned on, the transistor 28 is also turned on.
The other end of P26 rapidly goes to the ground level. Therefore,
The current from the capacitors 21 and 25 causes the ICP 26
The ICP 26 instantaneously cuts off conduction at both ends. Note that the overcurrent flows through the ICP 26 only for a predetermined discharging time of the capacitors 21 and 25,
It is sufficient for the CP 26 to cut off the circuit by about 0.1 second. Therefore, the capacitors 21 and 25 only need to have a capacity that can hold the cutoff time.

Next, a case where the burglar cuts off the connection cords 14 and 15 between the connectors 2 and 3 without removing the connector 3 will be described. If the burglar first cuts off the connection code 15 between the connector 2 and the terminal 5 of the connector 3, the base of the transistor 23 is connected to the battery via the connection code 15.
1 is disconnected, so that it is at the ground level via the resistor 13. Thus, the transistor 23 is turned on, but the transistor 29 is turned on, so that the transistor 27 is also turned on.

When the transistors 27 and 29 are turned on, the transistor 28 is also turned on.
The other end of P26 rapidly goes to the ground level. Therefore,
The battery is connected through the connection code 14 which is still connected.
Due to the current from 1, an overcurrent flows through the coil 20 and the diode 24 to the ICP 26, and the ICP 26 instantaneously cuts off conduction at both ends.

Next, the burglar first connects the connector 2 and the connector 3
The case where the connection cord 14 between the terminal 4 of FIG. After this disconnection, the capacitor 21 keeps the voltage applied between both terminals for a while. Subsequently, when the connection cord 15 between the connector 2 and the terminal 5 of the connector 3 is disconnected, the base of the transistor 23 goes to the ground level via the resistor 13, so that the capacitor
The transistor 23 is turned on by the current from 21 .
Therefore, this current turns on the transistor 27 via the coil 20 and the transistor 23.

When the transistor 27 is turned on, the transistor 28 is also turned on. Transistor 29
Is already on because the alarm set terminal 42 is "H". Therefore, the current from the capacitor 21 flows to the ground via the diode 24, the ICP 26, and the transistor 28. With this discharge current, the conduction at both ends of the ICP 26 is cut off.

After the connection cord 14 is cut off and the connection between the capacitor 21 and the battery 1 is cut off, a current flows from the very small amount of capacitor 21 to the amplifier, tuner and the like through the power supply line B1. Therefore, the terminal voltage of the capacitor 21 gradually decreases. Therefore, if the connection code 15 is disconnected after a considerable time has elapsed after the connection code 14 has been disconnected, the IC 21 will drop due to the voltage drop of the capacitor 21.
It is conceivable that a predetermined interruption current cannot be passed through P26.

However, since the capacitor 25 is connected in parallel with the capacitor 21 and the diode 24 is connected between the ICP 26 and the capacitor 21, the capacitor 25 The voltage drop of 25 is small. Therefore, when the connection code 15 is disconnected, the interruption current can be reliably supplied to the ICP 26 by the cooperation of the capacitors 21 and 25.

Of course, there may be a case where the terminal voltages of both the capacitors 21 and 25 are so low that they cannot supply a predetermined cut-off current of the ICP 26.
4 that you cut the connection cord 15 after the lapse of considerable long time after cutting is required. However, since the stolen person usually tries to steal the tape recorder 1 in a short time, the voltage drop state of the capacitors 21 and 25 is negligible.

As described above, when the connector 3 is stolen,
Is removed, or when the connection cords 14 and 15 are disconnected, the ICP 26 is shut off or the stolen tape recorder 10 is attached to the automobile and the ACC switch 11 is turned on (55). After setting the alarm set terminal 42 to the "L" level (56), the microcomputer 40 detects the level of the theft detection terminal 41 (57). In this case, since the ICP 26 is shut off, it becomes the "L" level. I have. Based on this detection, the microcomputer 40 does not accept all the keys in the tape recorder 10 and makes the tape recorder 10 inoperable (58). That is, the capacitors 21, 25,
Transistors 23, 27, 28, 29, IC protector
26 and the microcomputer 40 constitute a power cutoff detecting means.
You. Note that the IC protector 26 detects the power-off detection means.
It has a function of retaining the output result. More maiko
The tape drive 40 responds to the power cut-off detecting means to
A function as a control unit for disabling the coder 10
Also has.

When the ACC switch 11 is turned on,
Since ICP 26 is shut off, transistor 30 is turned off. Therefore, the transistor 31 is turned on,
By setting the cathode of the light-emitting diode 32 to the ground level, the light-emitting diode 32 is continuously lit, indicating that the tape recorder 10 is inoperable.

Here, the I which the stolen person is in the cut-off state
If it is possible to exchange CP26,
Although it is possible to operate the dapper 10, even if the thief has some electrical knowledge,
Normally, a large number of ICPs are used in the damper 10 for circuit protection, and it is impossible to determine whether or not the ICP is in a cut-off state in appearance. Further, since the ICP is very similar in appearance to semiconductor elements such as transistors, the ICP must be fully understood unless a specific circuit configuration is known.
It is virtually impossible to replace CP26.

Next, when the ACC switch 11 is turned off in a state where the anti-theft mode is not set because the FF key and the REW key are not double-pressed (51, 5).
4) The alarm set terminal 42 remains at "L" level. Therefore, the oscillator 34 does not output a pulse, and the light emitting diode 32 remains off.

When the burglar removes the connector 3 in this state, the transistor 29 is off, so that the transistors 23, 27, and 28 do not turn on. Therefore IC
No overcurrent flows through P26, and the circuit is not interrupted. In this case, since the anti-theft mode is not set,
The precoder 10 can operate normally after being stolen. When the tape recorder 10 is detached by a car dealer, a repair shop or the owner of the tape recorder 10 by itself, the anti-theft module is used. If the connector 3 is removed after the ACC switch 11 has been turned off without setting the negative switch, the ICP 26 will not be shut off.

After the FF key and the REW key are double-pressed (51), if 5 seconds have elapsed without turning off the ACC switch 11 (52, 59), the FF key and the REW key are depressed. No double push was made and then ACC
Even when the switch 11 is turned off, the alarm set terminal 42 is kept at the "L" level as described above (54, 55,
56).

When the battery 1 is replaced, the connection cord connected to the terminal of the battery 1 is removed. In this case, the base 2 of the transistor 23 is connected by the connector 2. Since the voltage of the capacitor 21 is similarly applied to the base emitter, the transistor 23 does not turn on and the ICP 26 does not cut off the circuit.

In the above-described embodiment, after detecting that two power supply lines have been cut off, an overcurrent is supplied to the IC protector to shut off the IC protector. Due to this interruption, the tape recorder becomes inoperable thereafter unless the IC protector is replaced. However, the present invention is not limited to this, and can be made operable when a correct recitation number is input after being stolen as in the conventional example.

In the above-described embodiment, two power supply lines are connected to one connector. However, the present invention is not limited to this. It is also possible to provide a connector for each of the two power supply lines.

Although the above-described embodiment uses an IC protector as a means for detecting and storing the theft, the present invention is not limited to this. Can also be used. In this case, it is desirable to use a fuse which has a small breaking current and can be broken at a high speed.

[0040]

As described above, according to the present invention, when the audio equipment is stolen, it is detected that one or both of the two power supply lines connecting the automobile battery and the audio equipment are disconnected. In this case, the audio device is made inoperable even if the accessory switch is turned on thereafter. Therefore, the operation is not disabled when the battery is not stolen, for example, when the battery is replaced. Therefore, it is possible to provide an operation prohibition device for an audio device that can surely and accurately detect the theft.

[0041]

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a tape recorder to which the present invention is applied.

FIG. 2 is a flowchart relating to the operation of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 Connector 3 Connector 10 Tape recorder 11 Accessory switch 26 IC protector 34 Oscillator 40 Microcomputer 41 Theft detection terminal 42 Alarm set terminal 60 Operation part 62 Mechanism part 63 Tuner part

Claims (1)

(57) [Claims] 1. An operation prohibition device for an in-vehicle audio device which is connected to a battery of an automobile and operates by being supplied with power from the battery, wherein at least two power supply lines from the battery without passing through an accessory switch of the automobile are provided. Detecting that the connection between the first and second power supply lines for supplying power to the on-vehicle audio device from the battery and the first and second power supply lines has been disconnected by branching into a system Power cut-off detecting means, and the first and second power supplies in response to the power cut-off detecting means.
A control unit for disabling the in-vehicle audio device even after the line connection is restored , the operation prohibition device for the in-vehicle audio device.