Pop-up, precision lock-cylinder that reveals at once, with visual and tactile cues, who else with a key has sought or gained entry

• US 6,516,643 B1
• Filed: 06/09/2000
• Issued: 02/11/2003
• Est. Priority Date: 06/09/2000
• Status: Expired due to Fees

• Current Assignee: Michael Cohnitz Olshausen
• Original Assignee: Michael Cohnitz Olshausen
• Inventors: Olshausen, Michael Cohnitz
• Primary Examiner(s): BARRETT, SUZANNE LALE DINO
• Application Number:
  US09/590,694
• Time in Patent Office: 977 Days
• Field of Search: 703/37--43, 704/32, 704/38, 704/41, 703/79.R, 703/67, 703/69--71
• US Class Current: 70/337
• CPC Class Codes: E05B 27/0053 for use with more than one key, e.g. master-slave key master key systems in general E05B35/10
• CPC Class Codes: E05B 41/00 Locks with visible indication as to whether the lock is locked or unlocked indicator lights E05B17/10
• CPC Class Codes: Y10T 70/7446 Multiple keys
• CPC Class Codes: Y10T 70/7463 Master- and change-key
• CPC Class Codes: Y10T 70/7638 Cylinder and plug assembly
• CPC Class Codes: Y10T 70/8027 Condition indicators
• CPC Class Codes: Y10T 70/827 Attention-directing

Abstract

Pop-Up Indicator, Replacement Lock-Cylinder with distinctive keys for owner, employee (or acquaintance), and some third party whose right to enter is legitimate only upon notice or in an emergency. The pop-up indicators are brightly and differently colored. The lock cannot be circumvented by pressing a pop-up in and endeavoring to turn the key, because the pop-up'"'"'s barrel blocks rotation of the lock'"'"'s core unless the pop-up is fully extended. Once triggered, the pop-up remains visible and in locked position until the lock owner resets it. A tactile indicator of sought entry is transmitted to the owner upon key insertion and rotation, as well. Meanwhile, the employee and/or third party enjoys unimpeded access. The owner will thus know whether the employee has been over—to inspect for termites, walk the dog, etc.—and the third party cannot allege lockout lease breaking. The lock operates quite normally with either or both pop-ups triggered. Since only the employee'"'"'s key or the third-party key (but not the owner'"'"'s key) is capable of triggering a pop-up, if these keys have been given out, the owner obtains prima facie proof of sought entry. The owner may wish to leave a pop-up exposed in order to show a witness or possibly the police.

Claims

1. A lock having a face, a core, an indicator means, a first key and a second key, said core having a keyway adapted for the insertion into said core either of said first key or said second key, said core being rotatable in said lock after insertion of said first key into said keyway, and said core being rotatable in said lock after insertion of said second key into said keyway, said indicator means having an armed position and an indicator position, said indicator means when in said armed position extending at most a short distance from said face of said lock, said indicator means when in said indicator position extending a substantially greater distance from said face of said lock, and in which a rotation of said first key, after insertion of said first key into said keyway, results in a movement of said indicator means from said armed position to said indicator position, and in which, said movement of said indicator means having occurred, a rotation of said second key, after insertion of said second key into said keyway, permits said indicator means to be moved from said indicator position to said armed position, but in which, said movement of said indicator means having occurred, rotation by said first key of said core does not permit said indicator means to be moved from said indicator position to said armed position.

2. A lock as in claim 1 wherein said first key has a grip and second key has a grip, and said grip of said first key is dissimilar geometrically to said grip of said second key.

3. A lock as in claim 1 wherein said first key has a grip and second key has a grip, and wherein said grip of said first key has an identifying aperture and said grip of said second key has an identifying aperture, and said identifying aperture of said first key is dissimilar geometrically to said identifying aperture of said second key.

4. A lock as in claim 1 wherein rotation by a person of said second key, after the insertion of said second key into said keyway and when said indicator means is in said indicator position, transmits to said person a tactile sensation different from the tactile sensation transmitted to said person when said indicator means is in said armed position and said person rotates said second key after insertion of said second key into said keyway.

5. A lock having a face, a core, a first indicator means, a second indicator means, a first key, a second key, and a third key, said core having a keyway adapted for the insertion into said core of either said first key or said second key or said third key, said core being rotatable in said lock after insertion of said first key into said keyway, or after insertion of said second key into said keyway, or after insertion of said third key into said keyway, said first indicator means having an armed position A and an indicator position AA, and said second indicator means having an armed position B and an indicator position BB, said first indicator means when in said armed position A extending at most a short distance from said face of said lock, said first indicator means when in said indicator position AA extending a substantially greater distance from said face of said lock, and said second indicator means when in said armed position B extending at most a short distance from said face of said lock, said second indicator means when in said indicator position BB extending a substantially greater distance from said face of said lock, and in which a rotation of said first key, after insertion of said first key into said keyway, results in a movement of said first indicator means from said armed position A to said indicator position AA, and in which a rotation of said second key, after insertion of said second key into said keyway, results in a movement of said second indicator means from said armed position B to said indicator position BB, and in which, said movement of said first indicator means having occurred, a rotation of said third key, after insertion of said third key into said keyway, permits said first indicator means to be moved from said indicator position AA to said armed position A, and in which, said movement of said second indicator means having occurred, a rotation of said third key, after insertion of said third key into said keyway, permits said second indicator means to be moved from said indicator position BB to said armed position B, but in which, said movement of said first indicator means having occurred, a rotation by either said first key or by said second key of said core does not permit said first indicator means to be moved from said indicator position AA to said armed position A, and in which said movement of said second indicator means having occurred, a rotation by either said first key or by said second key of said core does not permit said second indicator means to be moved from said indicator position BB to said armed position B.

6. A lock as in claim 5 wherein said first key has a grip, second key has a grip, and said third key has a grip, and wherein said grips of said first and second keys are geometrically dissimilar, but in which said grip of said third key is similar geometrically to one of said grips of said first and second keys.

7. A lock as in claim 5 wherein said first key has a grip, second key has a grip, and said third key has a grip, wherein said grip of said first key has an identifying aperture, said grip of said second key has an identifying aperture, and said grip of said third key has an identifying aperture, and wherein no two of said identifying apertures are geometrically similar.

8. A lock as in claim 5 wherein rotation by a person of said third key, after the insertion of said third key into said keyway and when both said first indicator means and said second indicator means are in their respective said armed positions A and B, transmits to said person a first tactile sensation, and wherein rotation by said person of said third key, after the insertion of said third key into said keyway and when only one of said first indicator means and said second indicator means is in said armed position A or said armed position B, transmits to said persona second tactile sensation, and wherein rotation by said person of said third key, after the insertion of said third key into said keyway and when neither said first indicator means nor said second indicator means is in said armed position A or said armed position B, transmits to said person a third tactile sensation, and wherein no two of said first, said second, and said third tactile sensations are the same.

9. A lock as in claim 5 wherein said first indicator means when in said indicator position AA displays a first colored marking, and wherein said second indicator means when in said indicator position BB displays a second colored marking, and in which said first and second colored markings are not the same color.

10. A lock having a core, a trigger means, a reset means, an indicator means, a first key and a second key, said core having a keyway adapted for insertion either of said first key or said second key into said core, said core being rotatable in said lock after the insertion either of said first key or said second key into said keyway, said trigger means but not said reset means being rotatable in said lock after insertion of said first key into said keyway, said reset means but not said trigger means being rotatable in said lock after insertion of said second key into said keyway, said reset means being contained entirely within said lock, said indicator means having an armed position and an indicator position, and in which a rotation of said trigger means results in a movement of said indicator means from said armed position to said indicator position, and further in which a rotation of said reset means permits said indicator means to be moved from said indicator position to said armed position, but in which a rotation of said trigger means does not permit said indicator means to be moved from said indicator position to said armed position.

11. A lock as in claim 10 wherein said lock has tumblers, and in which said trigger means has a substantially annular edge and a bore through which one of said tumblers is free to move, and in which said bore is tangent to said substantially annular edge.

12. A lock as in claim 10 wherein said lock has tumblers, and in which said reset means has a substantially annular edge and a bore through which one of said tumblers is free to move, and in which said bore is tangent to said substantially annular edge.

13. A lock as in claim 10 wherein said indicator means, when in said armed position, communicates with a compressed spring, and said compressed spring urges said indicator means out of said lock.

14. A lock as in claim 10 wherein said lock has a rear sleeve, and wherein said indicator means has a trough, said trough having a front wall and a rear wall, and in which said movement of said indicator means from said armed position to said indicator position is limited by the contact of said rear sleeve with said rear wall.

15. A lock as in claim 10 wherein said lock has a front sleeve, and wherein said indicator means has a trough, said trough having a front wall and a rear wall, and in which said movement of said indicator means from said indicator position to said armed position is limited by the contact of said front sleeve with said front wall.

16. A lock as in claim 14 or claim 15, said lock further having a means for retaining said sleeve in said lock, and in which said sleeve, when in contact with said trough, is not in contact with said means for retaining said sleeve.

17. A lock as in claim 14 or claim 15 wherein said indicator means is held in a cylindrical bore in said lock, and wherein said indicator means has a shape that is substantially cylindrical, said shape having a lengthwise axis, and wherein said trough has two side walls, and said indicator means is prevented from rotating about said lengthwise axis in said cylindrical bore by the obstruction of said side walls by said sleeve.

18. A lock as in claim 14 or claim 15 wherein said indicator means is held in a bore in said lock, and wherein said indicator means has a lengthwise axis, and wherein said sleeve is tubular in shape, said tubular shape having an inside diameter, and in which said sleeve contains an upper pin free to move within said sleeve, and further in which:

said indicator means has a bore orthogonal to said lengthwise axis and a lower pin free to move within said bore, and in which said lock is adapted to allow said upper pin and said lower pin to be brought into communication with each other, and in which said inside diameter of said sleeve is less than the diameter of said bore of said indicator means.

19. A lock as in claim 10 wherein said indicator means is held in a cylindrical bore in said lock and wherein said indicator means has a shape that is substantially cylindrical.

20. A lock as in claim 19 wherein said shape of said indicator means comprises a flat portion and a fully-cylindrical portion adjacent to said flat portion, and wherein said lock has tumblers, and further wherein said trigger means has a shape that is substantially tubular and is adapted to be mounted on said core, said trigger means further having a bore through which one of said tumblers is free to pass, said tumbler rotating always with said trigger means when said trigger means is rotated in said lock, and said tumbler is blocked from rotating in said lock by said fully-cylindrical portion of said indicator means when said indicator means is in said armed position.

21. A lock as in claim 19 in which said shape of said indicator means comprises a flat portion and a fully-cylindrical portion adjacent to said flat portion, and wherein said trigger means has a shape that is substantially tubular and is adapted to be mounted on said core, said trigger means further having a plateau portion extending radially outward from the outer surface of said tubular shape, and said plateau portion is blocked from rotation by said fully-cylindrical portion of said indicator means when said indicator means is in said armed position.

22. A lock as in claim 21 wherein said plateau portion of said trigger means has at least two beveled sides.

23. A lock as in claim 21 wherein said indicator means, when in said indicator position, remains locked in said indicator position until reset, and in which said plateau portion of said trigger means is first freed to rotate past said fully-cylindrical portion of said indicator means only after said indicator means has locked in said indicator position.

24. A lock as in claim 20 wherein said indicator means, when in said indicator position, remains locked in said indicator position until reset, and in which said tumbler is first freed to rotate past said fully-cylindrical portion of said indicator means only after said indicator means has locked in said indicator position.

25. A lock as in claim 19 in which said indicator means has a lengthwise axis and a bore orthogonal to said axis, and in which said indicator means when in said armed position remains locked in said armed position by a pin in said bore and movable in said bore, and in which said trigger means is adapted to lift said pin when said trigger means is rotated by said first key, said pin, when lifted by said trigger means, freeing said indicator means to move from said armed position to said indicator position.

26. A lock as in claim 25 in which said trigger means has a wedge-shaped cutout adapted to communicate with and to lift said pin.

27. A lock as in claim 26 wherein said wedge-shaped cutout has two beveled faces that do not intersect.

28. A lock as in claim 26 wherein said trigger means has an annular edge and a parallel, substantially annular edge, and said wedge-shaped cutout intersects said substantially annular edge.

29. A lock as in claim 28 wherein said wedge-shaped cutout has a face, and in which said face is a plane, said plane being parallel to said substantially annular edge, but said plane being closer to said annular edge.

30. A lock as in claim 19 in which said indicator means has a lengthwise axis and a bore orthogonal to said lengthwise axis, and in which said indicator means when in said indicator position remains locked in said indicator position by a pin in said bore and movable in said bore, and in which said reset means is adapted to lift said pin when said reset means is rotated by said second key, said pin when lifted by said reset means freeing said indicator means to move from said indicator position to said armed position.

31. A lock as in claim 30 wherein said reset means has a shape that is substantially tubular and is adapted to be mounted on said core, said reset means further having at least one plateau portion extending radially outward from the outer surface of said tubular shape, said plateau portion being adapted to lift said pin when said reset means is rotated by said second key.

32. A lock as in claim 31 wherein each plateau portion of said reset means has at least two beveled sides.

33. A lock having a core, a first trigger means, a second trigger means, a reset means, a first indicator means, a second indicator means, a first key, a second key, and a third key, said core having a keyway adapted for insertion either of said first key or said second key or said third key into said core, said core being rotatable in said lock after the insertion either of said first key or said second key or said third key into said keyway, said first trigger means but neither said second trigger means nor said reset means being rotatable in said lock after insertion of said first key into said keyway, said second trigger means but neither said first trigger means nor said reset means being rotatable in said lock after insertion of said second key into said keyway, said reset means but neither said first trigger means nor said second trigger means being rotatable in said lock after insertion of said third key into said keyway, said first indicator means having an armed position A and an indicator position AA, and said second indicator means having an armed position B and an indicator position BB, and in which rotation of said first trigger means results in a movement of said first indicator means from said armed position A to said indicator position AA, and in which rotation of said second trigger means results in a movement of said second indicator means from said armed position B to said indicator position BB, and in which rotation of said reset means permits said first indicator means to be moved from said indicator position AA to said armed position A, and furthermore in which rotation of said reset means permits said second indicator means to be moved from said indicator position BB to said armed position B, but in which rotation neither of said first trigger means nor of said second trigger means permits said first indicator means to be moved from said indicator position AA to said armed position A, and in which rotation neither of said first trigger means nor of said second trigger means permits said second indicator means to be moved from said indicator position BB to said armed position B.

34. A lock as in claim 33 in which said lock has tumblers, and in which said first trigger means has a substantially annular edge and a bore through which one of said tumblers is free to move, said bore of said first trigger means being tangent to said substantially annular edge of said first trigger means, and in which said second trigger means has a substantially annular edge and a bore through which another of said tumblers is free to move, said bore of said second trigger means being tangent to said substantially annular edge of said second trigger means.

35. A lock as in claim 33 in which said lock has tumblers, and in which said reset means has a substantially annular edge and a bore through which one of said tumblers is free to move, and in which said bore is tangent to said substantially annular edge.

36. A lock as in claim 33 wherein said first indicator means, when in said armed position A, communicates with a first compressed spring, and said first compressed spring urges said first indicator means out of said lock, and wherein said second indicator means, when in said armed position B, communicates with a second compressed spring, and said second compressed spring urges said second indicator means out of said lock.

37. A lock as in claim 33 wherein said lock has a first rear sleeve and a second rear sleeve, and wherein said first indicator means has a trough, said trough having a front wall and a rear wall, and in which said movement of said first indicator means from said armed position A to said indicator position AA is limited by the contact of said first rear sleeve with said rear wall of said trough, and wherein said second indicator means has a similar trough, said similar trough having a front wall and a rear wall, and in which said movement of said second indicator means from said armed position B to said indicator position BB is limited by the contact of said second rear sleeve with said rear wall of said similar trough.

38. A lock as in claim 33 wherein said lock has a first front sleeve and a second front sleeve, and wherein said first indicator means has a trough, said trough having a front wall and a rear wall, and in which said movement of said first indicator means from said indicator position AA to said armed position A is limited by the contact of said first front sleeve with said front wall of said trough, and wherein said second indicator means has a similar trough, said similar trough having a front wall and a rear wall, and in which said movement of said second indicator means from said indicator position BB to said armed position B is limited by the contact of said second front sleeve with said front wall of said similar trough.

39. A lock as in claim 37 or claim 38, said lock further having means for retaining said sleeves in said lock, and in which said sleeves, when in contact with said troughs, are not in contact with said means for retaining said sleeves.

40. A lock as in claim 37 or claim 38 wherein said first indicator means is held in a first cylindrical bore in said lock and said second indicator means is held in a second cylindrical bore in said lock, and wherein said first indicator means has a shape that is substantially cylindrical, said shape having lengthwise axis X1, and wherein said trough of said first indicator means has two side walls, and in which said first indicator means is prevented from rotating about said lengthwise axis X1 in said first cylindrical bore by the obstruction of said side walls of said trough by said first sleeve, and wherein said second indicator means also has a shape that is substantially cylindrical, said shape of said second indicator means having lengthwise axis X2, and wherein said similar trough of said second indicator means has two side walls, and in which said second indicator means is prevented from rotating about said lengthwise axis X2 in said second cylindrical bore by the obstruction of said side walls of said similar trough by said second sleeve.

41. A lock as in claim 37 or claim 38 wherein said first indicator means is held in a first bore in said lock and said second indicator means is held in a second bore in said lock, and in which said first indicator means has lengthwise axis X1, and in which said first sleeve is tubular in shape, said tubular shape having an inside diameter, and in which said first sleeve contains a first upper pin free to move within said first sleeve, and further in which said first indicator means has a bore orthogonal to said lengthwise axis X1 and a first lower pin free to move within said bore, said lock being adapted to allow said first upper pin and said first lower pin to be brought into communication with each other, and in which said inside diameter of said first sleeve is less than the diameter of said bore in said first indicator means, and wherein said second indicator means has lengthwise axis X2, and wherein said second sleeve is tubular in shape, said tubular shape having an inside diameter, and in which said second sleeve contains a second upper pin free to move within said second sleeve, and further in which said second indicator means has a similar bore orthogonal to said lengthwise axis X2 and a second lower pin free to move within said similar bore, said lock being adapted to allow said second upper pin and said second lower pin to be brought into communication with each other, and in which said inside diameter of said second sleeve is less than the diameter of said similar bore of said second indicator means.

42. A lock as in claim 33 wherein said first and second indicator means are held in separate, cylindrical bores in said lock and wherein said first indicator means has a shape that is substantially cylindrical, and wherein second indicator means has a shape that is substantially cylindrical.

43. A lock as in claim 33 wherein said first and second indicator means each have colored portions, said indicator means being adapted to prevent said colored portions from rubbing against said lock when either of the said indicator means moves within said lock.

44. A lock as in claim 42 wherein said shape of said first indicator means comprises a flat portion and a fully-cylindrical portion adjacent to said flat portion, and wherein said shape of said second indicator means comprises two, flat, coplanar portions and a fully-cylindrical portion between said two, flat, coplanar portions, and wherein said lock has tumblers, and wherein said first trigger means has a shape that is substantially tubular and is adapted to be mounted on said core, said first trigger means having a bore through which one of said tumblers is free to pass, said one of said tumblers rotating always with said first trigger means when said first trigger means is rotated in said lock, and wherein said second trigger means has a shape that is substantially tubular and is adapted to be mounted on said core, said second trigger means having a bore through which another of said tumblers is free to pass, said another of said tumblers rotating always with said second trigger means when said second trigger means is rotated in said lock, and in which said one of said tumblers is blocked from rotating in said lock by said fully-cylindrical portion of said first indicator means when said first indicator means is in said armed position A, and in which said another of said tumblers is blocked from rotating in said lock by said fully-cylindrical portion of said second indicator means when said second indicator means is in said armed position B.

45. A lock as in claim 42 wherein said shape of said first indicator means comprises a flat portion and a fully-cylindrical portion adjacent to said flat portion, and wherein said shape of said second indicator means comprises two, flat, coplanar portions and a fully-cylindrical portion between said two, flat, coplanar portions, and wherein said first trigger means has shape T1 that is substantially tubular and is adapted to be mounted on said core, said first trigger means further having a plateau portion extending radially outward from the outer surface of said tubular shape T1, and wherein said second trigger means has shape T2 that is substantially tubular and is adapted to be mounted on said core, said second trigger means further having a plateau portion extending radially outward from the outer surface of said tubular shape T2, said plateau portion of said first trigger means being blocked from rotation in said lock by said-fully cylindrical portion of said first indicator means when said first indicator means is in said armed position A, and said plateau portion of said second trigger means being blocked from rotation in said lock by said fully-cylindrical portion of said second indicator means when said second indicator means is in said armed position B.

46. A lock as in claim 45 in which said plateau portion of said first trigger means has at least two beveled flat sides, and in which said plateau portion of said second trigger means has at least two beveled flat sides.

47. A lock as in claim 44 or 45 in which said shapes of said first and second trigger means are congruent.

48. A lock as in claim 45 wherein said first indicator means, when in said indicator position AA, remains locked in said indicator position AA until reset, and in which said plateau portion of said first trigger means is first freed to rotate past said fully-cylindrical portion of said first indicator means only after said first indicator means has locked in said indicator position AA, and wherein said second indicator means, when in said indicator position BB, remains locked in said indicator position BB until reset, and in which said plateau portion of said second trigger means is first freed to rotate past said fully-cylindrical portion of said second indicator means only after said second indicator means has locked in said indicator position BB.

49. A lock as in claim 44 wherein said first indicator means, when in said indicator position AA, remains locked in said indicator position AA until reset, and in which said one of said tumblers is first freed to rotate past said fully-cylindrical portion of said first indicator means only after said first indicator means has locked in said indicator position AA, and in which said second indicator means, when in said indicator position BB, remains locked in said indicator position BB until reset, and in which said another of said tumblers is first freed to rotate past said fully-cylindrical portion of said second indicator means only after said second indicator means has locked in said indicator position BB.

50. A lock as in claim 42 wherein said first indicator means has a lengthwise axis and a bore orthogonal thereto, and in which said first indicator means, when in said armed position A, remains locked in said armed position A by a pin in said bore and movable in said bore, said first trigger means being adapted to lift said pin in said bore of said first indicator means when said first trigger means is rotated by said first key, said pin when lifted by said first trigger means freeing said first indicator means to move from said armed position A to said indicator position AA, and wherein said second indicator means has a lengthwise axis and a similar bore orthogonal thereto, and in which said second indicator means when in said armed position B remains locked in said armed position B by a pin in said similar bore and movable in said similar bore, and in which said second trigger means is adapted to lift said pin in said similar bore of said second indicator means when said second trigger means is rotated by said second key, said pin when lifted by said second trigger means freeing said second indicator means to move from said armed position B to its said indicator position BB.

51. A lock as in claim 50 wherein said first trigger means has a wedge-shaped cutout adapted to communicate with and to lift said pin in said bore of said first indicator means, and in which said second trigger means has a wedge-shaped cutout adapted to communicate with and to lift said pin in said bore of said second indicator means.

52. A lock as in claim 51 wherein each said wedge-shaped cutout has two beveled faces that do not intersect.

53. A lock as in claim 51 wherein each said trigger means has a substantially annular edge and a parallel, annular edge, and in which the said wedge-shaped cutout of each said trigger means intersects that said trigger mean'"'"'s said substantially annular edge.

54. A lock as in claim 53 wherein each said wedge-shaped cutout has a face, said face being a plane and said plane being parallel to the substantially annular edge of the said trigger means in which the said wedge-shaped cutout is located, said plane being closer, however, to the annular edge of the said trigger means in which the said wedge-shaped cutout is located.

55. A lock as in claim 42 wherein said first indicator means has a lengthwise axis and a bore orthogonal to said lengthwise axis, and in which said first indicator means when in said indicator position AA remains locked in its said indicator position AA by a pin in said bore and movable in said bore, and in which said reset means is adapted to lift said pin when said reset means is rotated by said third key, said pin when lifted by said reset means freeing said first indicator means to move from said indicator position AA to said armed position A, and wherein said second indicator means also has a lengthwise axis and a similar bore orthogonal thereto, and in which said second indicator means when in said indicator position BB remains locked in said indicator position BB by a pin in said similar bore and movable in said similar bore, and in which said reset means is adapted to lift said pin in said similar bore of said second indicator means when said reset means is rotated by said third key, said pin in said similar bore of said second indicator means when lifted by said reset means freeing said second indicator means to move from said indicator position BB to said armed position B.

56. A lock as in claim 55 wherein said reset means has a shape that is substantially tubular and is adapted to be mounted on said core, said reset means further having at least one plateau portion extending radially outward from the outer surface of said tubular shape, said plateau portion being adapted to lift either of said pins when said reset means is rotated by said third key.

57. A lock as in claim 56 wherein each plateau portion of said reset means has at least two beveled flat sides.

58. A lock comprising a core, a set of tumblers, a first key, a second key, a first indicator means having unobtrusive state A and indicator state AA, a second indicator means having unobtrusive state B and indicator state BB, said first key being rotatable in said lock, said rotation of said first key in said lock being sufficient to change the state of said first indicator means from said unobtrusive state A to said indicator state AA, said second key being rotatable in said lock, said rotation of said second key in said lock being sufficient to change the state of said second indicator means from said unobtrusive state B to said indicator state BB, said first key being rotatable in said lock whether or not said second key has been rotated in said lock, said second key being rotatable in said lock whether or not said first key has been rotated in said lock, said core having a lengthwise axis and a keyway into which said first and second keys may be inserted, said core having a number of bores, each bore having a reference point that locates said bore with respect to said core, all said reference points lying in a single plane parallel to said lengthwise axis of said core, said bores being adapted to hold said tumblers, said tumblers communicating with said first key when said first key is inserted into said keyway and said tumblers are in said bores, said tumblers further communicating with said second key when said second key is inserted into said keyway and said tumblers are in said bores, said number of bores being equal to the number of said tumblers, and said bores being located in said core such that the distance between the reference points of adjacent bores is not the same for all pairs of adjacent bores.

59. A lock as in claim 58 wherein said key has a set of keycuts, each keycut having a shape adapted to communicate with at least one of said tumblers, and in which the number of said keycuts is greater than the number of said tumblers.

60. A lock as in claim 58 wherein each keycut has a depth and in which at least one of said keycuts has a depth that may be altered without affecting the ability of said core to rotate in said lock when said key is inserted into said keyway.