US4808981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automotive electronic communication apparatus with theft disabling, particularly car radio or similar automotive audio equipment
Assignee: Blaupunkt Werke GmbH
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Filing: 1988-03-29
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Granted: 1989-02-28
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Expires: 2008-03-29
Abstract
Abstract To prevent overriding an electronic car radio theft disabling system by connecting an external battery to a car radio prior to theft thereof, the radio includes a measuring circuit (7, 7') measures the impedance of a connected accessory, for example a loudspeaker or loudspeaker system (8), and if the impedance of connected loudspeaker does not match the impedance stored in a memory (5) of the car radio, operation of the radio is inhibited until the appropriate code word--known only to the proper owner--is reinserted.
Inventors
- 👤 Peter Seibold
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:19
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/08; H04B1/082; B; B60; B60R; B60R11/00; B60R11/02; B60R11/0205; B60R2011/0096; B60R2011/0098; G; G08; G08B; G08B13/00; G08B13/02; G08B13/14; G08B13/22
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
176 words
Automotive electronic communication apparatus with theft disabling, particularly car radios or similar automotive audio equipment, comprising a memory (5) for storing (a) a selected code word, and (b) an impedance value; input means (1, 4) for entering code words into the memory; means (1) for preventing operation of the communication apparatus (2) until the selected code word is entered for storage into the memory after removal of the radio, and comprising measuring means (7, 7') coupled to an accessory terminal (9) of the communication apparatus (2) and measuring impedance of accessory equipment (8) connected to said terminal; and comparator means (1) coupled to the communication apparatus (2) and controlling operation thereof, said comparator means comparing the impedance of the accessory equipment (8) coupled to said accessory terminal (9) with the impedance value stored in the memory (5) and (i) upon coincidence, permitting operation of the communication apparatus (2), and (ii) upon non-coincidence, inhibiting operation of the communication apparatus until the selected code word, stored in the memory, is again entered into the input means (1, 4).
Claim 2
Dependent Claim
176 words
Automotive electronic communication apparatus with theft disabling, particularly car radios or similar automotive audio equipment, comprising a memory (5) for storing (a) a selected code word, and (b) an impedance value; input means (1, 4) for entering code words into the memory; means (1) for preventing operation of the communication apparatus (2) until the selected code word is entered for storage into the memory after removal of the radio, and comprising measuring means (7, 7') coupled to an accessory terminal (9) of the communication apparatus (2) and measuring impedance of accessory equipment (8) connected to said terminal; and comparator means (1) coupled to the communication apparatus (2) and controlling operation thereof, said comparator means comparing the impedance of the accessory equipment (8) coupled to said accessory terminal (9) with the impedance value stored in the memory (5) and (i) upon coincidence, permitting operation of the communication apparatus (2), and (ii) upon non-coincidence, inhibiting operation of the communication apparatus until the selected code word, stored in the memory, is again entered into the input means (1, 4).
Claim 3
Dependent Claim
27 words
The apparatus of claim 1, wherein said accessory terminal (9) comprises at least one loudspeaker terminal, and said accessory equipment comprises a loudspeaker or a loudspeaker system.
Claim 4
Dependent Claim
35 words
The apparatus of claim 2, wherein the impedance measuring means includes an alternating voltage or signal generator (13) and transfer switch means (10) selectively connecting an alternating signal to said loudspeaker or loudspeaker system (8).
Claim 5
Dependent Claim
21 words
The apparatus of claim 3, wherein the signal generated by said voltage or signal generator (13) is in the super-audible range.
Claim 6
Dependent Claim
24 words
The apparatus of claim 3, wherein the signal generated by said voltage or signal generator (13) is in the order of about 40 kHz.
Claim 7
Dependent Claim
33 words
The apparatus of claim 3, wherein the measuring means (7) comprises current sensing means (W, 14) coupled to said accessory terminal (9) and determining current flow to said loudspeaker or loudspeaker system (9).
Claim 8
Dependent Claim
25 words
The apparatus of claim 6, wherein said measuring means further includes circuit connection means (16, 16', 18) having said alternating signal or frequency applied thereto.
Claim 9
Dependent Claim
62 words
The apparatus of claim 6, further including phase comparator means (20) comparing the phase of current flow to said accessory terminal and said loudspeaker or loudspeaker system with the phase of signals derived from said signal or frequency generating means; and circuit means (22, 23, 6) deriving a measured voltage representative of phase comparison signals derived from said phase comparator means (20).
Claim 10
Dependent Claim
21 words
The apparatus of claim 7, wherein the signal generated by said voltage or signal generator (13) is in the super-audible range.
Claim 11
Dependent Claim
24 words
The apparatus of claim 7, wherein the signal generated by said voltage or signal generator (13) is in the order of about 40 kHz.
Claim 12
Dependent Claim
21 words
The apparatus of claim 8, wherein the signal generated by said voltage or signal generator (13) is in the super-audible range.
Claim 13
Dependent Claim
24 words
The apparatus of claim 8, wherein the signal generated by said voltage or signal generator (13) is in the order of about 40 kHz.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |