US5455571A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fail safe system for a mechanical lock key set with electronic interlock
Assignee: Strattec Security Corp
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Filing: 1994-01-10
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Granted: 1995-10-03
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Expires: 2014-01-10
Abstract
Abstract A mechanical key and lock set with a rotating cylinder includes an electronic interlock which is responsive to the insertion of a mated key in the cylinder and proper rotation of the cylinder. A sensor is placed in communication with the cylinder and senses proper rotation of the cylinder to generate an activation signal. Systems controlled by the lock cannot be enabled without the generation of the activation signal. Fail safe blocking circuitry is placed in communication with the activation signal generator and in the event the actuation signal is attempted to be read in an unauthorized manner without properly rotating the cylinder, the blocking circuitry is functional to preclude reading.
Inventors
- 👤 David C. Janssen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:10
CPC Classifications
G; G07; G07C; G07C9/00; G07C9/00174; G07C9/00658; G07C9/00722; G07C9/00738
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
239 words
A fail safe circuit adapted for preventing the deciphering of a coded electronic interlock for a mechanical lock, the lock having a rotatable cylinder and a mated key used in a normal mode for unlocking a system when the mated key is inserted in the cylinder, and the key and the cylinder are rotated from a lock position to an unlock position, the interlock disabling the system until a preselected coded signal is generated in response to the rotation of the key and cylinder, the interlock including an interlock sensor for determining the rotation of the cylinder and the key and a signal generator for generating the coded signal in response to rotation of the cylinder and key, the fail safe circuit being in communication with the signal generator and operable for preventing the unauthorized reading of the value of the preselected resistance element when a mated key is not present in the cylinder, and the mechanical lock and the cylinder are not properly rotated, the fail safe device comprising: a bypass circuit disposed in parallel with the signal generator and the preselected resistance element, the bypass circuit dormant when the cylinder is properly rotated to generate the coded signal, and the bypass circuit generating a false coded signal when activated so as to prevent the unauthorized reading of the value of the preselected code when a mated key is not present in the cylinder of the mechanical lock.
Claim 2
Dependent Claim
239 words
A fail safe circuit adapted for preventing the deciphering of a coded electronic interlock for a mechanical lock, the lock having a rotatable cylinder and a mated key used in a normal mode for unlocking a system when the mated key is inserted in the cylinder, and the key and the cylinder are rotated from a lock position to an unlock position, the interlock disabling the system until a preselected coded signal is generated in response to the rotation of the key and cylinder, the interlock including an interlock sensor for determining the rotation of the cylinder and the key and a signal generator for generating the coded signal in response to rotation of the cylinder and key, the fail safe circuit being in communication with the signal generator and operable for preventing the unauthorized reading of the value of the preselected resistance element when a mated key is not present in the cylinder, and the mechanical lock and the cylinder are not properly rotated, the fail safe device comprising: a bypass circuit disposed in parallel with the signal generator and the preselected resistance element, the bypass circuit dormant when the cylinder is properly rotated to generate the coded signal, and the bypass circuit generating a false coded signal when activated so as to prevent the unauthorized reading of the value of the preselected code when a mated key is not present in the cylinder of the mechanical lock.
Claim 3
Dependent Claim
33 words
The fail safe circuit of claim 1 further comprising a sensor for activating the bypass circuit in response to a magnetic field generated outside the mechanical lock in the proximity to the sensor.
Claim 4
Dependent Claim
40 words
The fail safe circuit of claim 2 further comprising a comparator circuit in communication with the signal generator for receiving the coded signal, the comparator circuit operable for unlocking the system when the coded signal is within an acceptable range.
Claim 5
Dependent Claim
47 words
The fail safe circuit of claim 2 wherein the cylinder includes a permanent magnet mounted on the periphery thereof and wherein the interlock sensor includes a Hall effect element which generates a signal in response to the proximity of the cylinder magnet relative to the interlock sensor.
Claim 6
Dependent Claim
59 words
The fail safe circuit of claim 4 wherein the bypass circuit includes a transistor switch, the transistor switch normally turned off when the cylinder is rotated with the mated key inserted in the cylinder and turned on to activate the bypass circuit in response to a magnetic field generated outside of the cylinder in proximity of the interlock sensor.
Claim 7
Dependent Claim
40 words
The fail safe circuit of claim 5 further comprising a comparator circuit in communication with the signal generator for receiving the coded signal, the comparator circuit operable for unlocking the system when the coded signal is within an acceptable range.
Claim 8
Dependent Claim
39 words
The fail safe circuit of claim 5 wherein the bypass circuit includes a second transistor switch, the second transistor switch normally off when the first transistor switch is off, and normally on when the first transistor switch is on.
Claim 9
Dependent Claim
28 words
The fail safe circuit of claim i further comprising a means for generating the false coded signal in response to a reverse voltage across terminals of the interlock.
Claim 10
Dependent Claim
108 words
A fail safe circuit for a mechanical lock, having a cylinder and a mated key for unlocking a system when the mated key is inserted in a cylinder and the key and cylinder are rotated from a locked position to an unlocked position, the mechanical lock including an interlock which generates a preselected coded signal in response to rotation of the key and cylinder so as to enable the system, the fail safe circuit comprising: means for generating a false coded signal in response to a magnetic field generated outside the cylinder and in proximity to the lock, the false coded signal precluding the enabling of the system.
Claim 11
Dependent Claim
108 words
A fail safe circuit for a mechanical lock, having a cylinder and a mated key for unlocking a system when the mated key is inserted in a cylinder and the key and cylinder are rotated from a locked position to an unlocked position, the mechanical lock including an interlock which generates a preselected coded signal in response to rotation of the key and cylinder so as to enable the system, the fail safe circuit comprising: means for generating a false coded signal in response to a magnetic field generated outside the cylinder and in proximity to the lock, the false coded signal precluding the enabling of the system.
Claim 12
Dependent Claim
68 words
The fail safe circuit of claim 9, wherein the means for generating the false coded signal comprises: a sensor for sensing a magnetic field in proximity to the mechanical lock and for generating an activation signal in response thereto; and a bypass circuit operatively connected to the sensor and the interlock, the bypass circuit generating a false coded signal in response to the activation signal from the sensor.
Claim 13
Dependent Claim
53 words
The device of claim 10, wherein the interlock comprises: an interlock sensor for determining the rotation of the cylinder and key; and a signal generator having a preselected resistance code controlled by the interlock sensor, the signal generator generating the coded signal in response to the rotation of the cylinder and the key.
Claim 14
Dependent Claim
40 words
The fail safe circuit of claim 11 further comprising a comparator circuit in communication with the signal generator for receiving the coded signal, the comparator circuit operable for unlocking the system when the coded signal is within an acceptable range.
Claim 15
Dependent Claim
57 words
The fail safe circuit of claim 12 wherein the interlock sensor includes a Hall effect element for reading the presence of a magnetic field emanating from the cylinder, and wherein the cylinder includes a permanent magnet located on the outer periphery thereof which is rotated in proximity of the Hall effect element when the cylinder is rotated.
Claim 16
Dependent Claim
28 words
The fail safe circuit of claim 9 further comprising a means for generating the false coded signal in response to a reverse voltage across terminals of the interlock.
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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) | 1998-10-02 | 1999-04-03 | 1999-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-10-02 | 2003-04-03 | 2003-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-10-02 | 2007-04-03 | 2007-10-03 | $7700.00 | Window Closed / Lapsed |