JPH0449746Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an anti-theft device for in-vehicle equipment.

BACKGROUND TECHNOLOGY As an anti-theft device, a device has already been devised that indirectly prevents theft by having an anti-theft function that prevents in-vehicle equipment from operating normally even after the power is turned on once it has been removed from the vehicle body. has been done. In such conventional devices, a control circuit such as a microcomputer that controls the entire device detects whether the device has been removed from the vehicle body by detecting that the electrical connection between the devices, such as a battery, has been interrupted. is configured to detect.
The anti-theft function of such a conventional device is canceled by inputting a numeric code string identical to a pre-stored numeric code string (hereinafter referred to as a security code) from a keyboard or the like.

Since such conventional anti-theft devices wait for an input from a keyboard to activate, various security codes must be entered for each device during the assembly or inspection process of devices including the anti-theft device. It is not possible to carry out inspections, etc., and there is a problem that work efficiency decreases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an anti-theft device for in-vehicle equipment that can operate when necessary without input from a keyboard.

In order to achieve the above object, in the anti-theft device according to the present invention, the memory is freely updatable and an initial code is stored as an initial value, and the code input from the keyboard matches the initial code representing a command to stop the anti-theft function. The device has a comparison means for determining whether or not the two devices match, and when they match, the device can be put into an operable state without waiting for the input of a security code for each user.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIG. A power supply voltage from a power supply 1 is applied via a connection terminal 2 to a voltage converter 3, a relay contact 4a serving as an activation means, and one end of a relay coil 4b. The voltage converter 3 converts the power supply voltage level to a bias voltage level for a microprocessor, etc., and applies it to the control circuit 5. The other end of the relay contact 4a is connected to an on-vehicle device 6 such as a cassette tape deck or tuner to supply power. The other end of relay coil 4b is grounded via drive transistor 7. The drive transistor 7 and the on-vehicle device 6 operate according to a control signal supplied from the control circuit 5. The detection circuit 8 monitors the operating state of the on-vehicle equipment 6 and sends the obtained control information to the control circuit 5.
supply to.

Further, the control circuit 5 is supplied with a code signal representing numbers as a security code or other operation commands from a keyboard 9 serving as input operation means. The control circuit 5 includes a microprocessor, a ROM in which a control program is stored, a RAM in which the above code signals, etc. are stored, and a keyboard 9.
A keyboard control circuit that controls the drive transistor 7, an input/output circuit that sends and receives signals to and from the mechanism drive circuit 6 and the detection circuit 8. When power is supplied, the circuit is set to the initial state and the microprocessor is set to the ROM. It is constructed by a so-called power-on reset circuit (not shown) that automatically executes a program stored at a predetermined address in the program.
The nonvolatile memory 10, which is an updatable memory, stores the latest code signal supplied from the control circuit 5, and does not lose its stored information even if the power supply is cut off due to disconnection of the connection terminal 2 or the like.

Next, the control operation of the control circuit 5 will be explained with reference to the flowchart shown in FIG.
When the connection terminal 2 is connected and power is supplied from the power supply 1 to the control circuit 5, the above-mentioned microprocessor starts up and starts executing the main control program stored in the ROM to confirm the security code input. Move to another subroutine. First, a code signal stored at a predetermined address in the nonvolatile memory 10 is read out and stored in the register of the microprocessor (step S ₁ ). If this read code signal matches an initial code written in the program or separately stored in the non-volatile memory 10 indicating a command to cancel the anti-theft function, for example "0000", a step is taken to activate the security function. , and move on to step _S5 (step _S2 ). Here, steps S ₁ and S ₂ are the first
Corresponds to the means of comparison. If the code signal read from the nonvolatile memory 10 does not match the initial code (step S ₂ ), the microprocessor waits for input of a series of codes from the keyboard 9 (step S ₃ ). When a code group is input from the keyboard 9 and this code group matches the read code signal, for example "1111", the process returns to step _S5 ;
If they do not match, the process returns to step _S3 and waits for the code group to be input again. During this time, the switch 4a is not closed and the on-vehicle device 6 cannot operate. Here, steps S ₃ and S ₄ correspond to the second comparison means. In this manner, the control circuit 5 waits for a command to indicate whether or not to change the stored code signal by indicating on the display panel of an in-vehicle device such as a tape deck or tuner (step _S5 ). The operator is
For example, if the code in the memory 10 is to be changed, such as by inputting a security code from the keyboard 9, "1" is entered, and if the code is not to be changed, "0" is entered. When a code change is commanded and a new code group is input from the keyboard 9 (step S ₆ ),
The microprocessor stores this code group as a new security code in the non-volatile memory 10 and updates the conventional stored code signal (step
_S7 ). When a command indicating that there is no change in the memory code is issued (step _S5 ) or when step _S7 is completed, the microprocessor issues an operation command signal to the activation means, and relay contact 4a closes to activate the on-vehicle equipment. Output power is supplied to 6. And in-vehicle equipment 6
becomes available for use (step _S8 ). here,
Steps _S5 and _S6 correspond to determination means. Also,
Steps _S7 and _S8 correspond to relay means. After completing step _S8 , the flag indicating the end of the subroutine is set to "1", and the process returns to the main control program described above to end the subroutine.

In this way, if the security code consisting of an arbitrary code unique to the user is stored, the anti-theft function is automatically activated, and when the initial code is stored, the anti-theft function is canceled. It is.

Incidentally, steps _S5 to _S7 can be made independent as a security code changing subroutine, and can be called from the main control program according to the operation. In such a case, if the initial code is stored, the input operation (step _S5 ) will return directly to the main control program from step _S2 .
This also saves time and effort. Note that the initial code is not limited to "0000" as described above.

Effects of the Invention As explained above, the anti-theft device for in-vehicle equipment according to the present invention has a first comparison means for identifying whether or not the stored security code matches a predetermined initial code. If the code is memorized, the anti-theft function is canceled, and the specific security code is entered only when the anti-theft function is required to activate the function, so it can be used for assembly, inspection, product display, etc. This is advantageous because it eliminates the need for code entry work and reduces the number of man-hours required.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG. 2 is a flowchart showing a subroutine of control operations. Explanation of symbols of main parts, 2... Connection terminal, 5...
...Control circuit, 10...Nonvolatile memory.

Claims (1)

[Scope of utility model registration request] activating means for enabling the in-vehicle device to operate in response to an operation command signal; a control circuit for issuing the operation command signal when a supplied input code signal satisfies a predetermined condition; and an input operation means for supplying the input code signal or rewriting request command, the control circuit storing the initial code signal and storing the latest code signal among the code signals supplied later. a non-volatile updatable memory for storing a first match signal; a second comparison means for generating a second coincidence signal when the input code signal and the code signal in the updatable memory match in the absence of the rewriting request command; issuing the operation command signal in response to the coincidence signal;
It has a determining means for issuing a standby command when the rewriting request command is present, and a relaying means for issuing the operation command after relaying the input code signal supplied while the standby command is being issued to the updatable memory. An anti-theft device for in-vehicle equipment, which is characterized by: