Antitheft apparatus and method for an automobile
First Claim
1. An antitheft apparatus for an automobile comprising:
- an identification code transmitting means for transmitting an initial identification code;
an immobilizing means for transmitting a variable code which is comprised of a plurality of blocks, wherein each of said plurality of blocks has a plurality of bits, further wherein at least one of said plurality of blocks is generated at random when electricity is supplied to the automobile and the remainder of said plurality of blocks are generated based upon a predetermined function of said at least one of said plurality of blocks and a predetermined key word for a predetermined period after electricity is supplied to the automobile, if the initial identification code and a predetermined identification code agree; and
a start inhibiting means for inhibiting the starting of an engine if a key word, which is decoded based on the variable code transmitted from said immobilizing means and said predetermined key word disagree, for a predetermined period after electricity is supplied to the automobile.
1 Assignment
0 Petitions
Accused Products
Abstract
If agreement between an identification code transmitted from a transmitter 111 installed in a door key 11 and a predetermined identification code is detected in an immobilizing ECU 12, a variable code including a predetermined key word is transmitted from the immobilizing ECU 12 to an engine ECU 13, and the variable code is decoded in the engine ECU 13. If the decoded key word does not agree with the predetermined key word, the starting of the engine is inhibited.
According to another aspect of this invention, a variable code is transmitted from the engine ECU 13 to the immobilizing ECU 12, a returning variable code is calculated based on a predetermined key function in the immobilizing ECU 12, and it returns to the engine ECU 13. If an agreement with returned variable code and a reference variable code determined in the engine ECU 13 is detected for the predetermined period, the starting of the engine is inhibited.
36 Citations
16 Claims
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1. An antitheft apparatus for an automobile comprising:
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an identification code transmitting means for transmitting an initial identification code; an immobilizing means for transmitting a variable code which is comprised of a plurality of blocks, wherein each of said plurality of blocks has a plurality of bits, further wherein at least one of said plurality of blocks is generated at random when electricity is supplied to the automobile and the remainder of said plurality of blocks are generated based upon a predetermined function of said at least one of said plurality of blocks and a predetermined key word for a predetermined period after electricity is supplied to the automobile, if the initial identification code and a predetermined identification code agree; and a start inhibiting means for inhibiting the starting of an engine if a key word, which is decoded based on the variable code transmitted from said immobilizing means and said predetermined key word disagree, for a predetermined period after electricity is supplied to the automobile. - View Dependent Claims (2, 3)
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4. An antitheft apparatus for an automobile comprising:
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an identification code transmitting means for transmitting an initial identification code; a variable code transmitting means for transmitting a variable code which is comprised of a plurality of blocks, wherein each of said plurality of blocks has a plurality of bits and each of said plurality of blocks is generated at random, for a predetermined period after electricity is supplied to the automobile, and calculating a reference code which is determined as a predetermined function of said plurality of blocks of said variable code when electricity is supplied to the automobile and reaches a predetermined operating condition; an immobilizing means for transmitting a return code which is calculated as a predetermined key function of said plurality of blocks of said variable code, if an agreement between said initial identification code and a predetermined identification code is detected; and a start inhibiting means for inhibiting the starting of an engine if an agreement between said return code transmitted from said immobilizing means and said reference code determined in said variable code transmitting means is not detected for a predetermined period after electricity is supplied to the automobile. - View Dependent Claims (5, 6, 7, 8)
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9. An antitheft method for an automobile comprising the steps of:
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transmitting an initial identification code; transmitting a variable code which is comprised of a plurality of blocks, wherein each of said plurality of blocks includes a plurality of bits, wherein at least one of said plurality of blocks is generated at random when electricity is supplied to the automobile and the remainder of the plurality of blocks thereof being determined as a predetermined function of said at least one plurality of blocks and a predetermined key word for a predetermined period after electricity is supplied to the automobile, if an agreement between the initial identification code and a predetermined identification code is detected; and inhibiting the starting of an engine if an agreement between a key word, which is decoded from the transmission variable code and said predetermined key word is not detected for a predetermined period after electricity is supplied to the automobile. - View Dependent Claims (10, 11)
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12. An antitheft method for an automobile comprising the steps of:
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transmitting an initial identification code; transmitting a variable code which is comprised of a plurality of blocks, wherein each of said plurality of blocks has a plurality of bits and is generated at random for a predetermined period after electricity is supplied to the automobile, and calculating a reference code which is determined as a predetermined function of said plurality of blocks of said variable code when electricity is supplied to the automobile and reaches a predetermined operating condition; transmitting a return code which is calculated as a predetermined key function of said plurality of blocks of said variable code, if an agreement between the initial identification code and a predetermined identification code is detected; and inhibiting the starting of an engine if agreement between a key word, which is decoded from the transmitted variable code and said predetermined key word is not detected. - View Dependent Claims (13, 14, 15, 16)
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Specification