Digital electrochromic mirror system

• US 6,299,315 B2
• Filed: 03/28/2001
• Issued: 10/09/2001
• Est. Priority Date: 04/02/1997
• Status: Expired due to Fees

• Current Assignee: Donnelly Corporation (Magna International Incorporated)
• Original Assignee: Donnelly Corporation (Magna International Incorporated)
• Inventors: Schierbeek, Kenneth L., Hoekstra, Eric J.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Robinson, Mark A.
• Application Number:
  US09/820,017
• Publication Number:
  US 20010010595A1
• Time in Patent Office: 195 Days
• Field of Search: 359/601, 359/602, 359/603, 359/604, 359/608, 359/265, 359/266, 359/267, 307/9.1
• US Class Current: 359/603
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors

Abstract

A vehicular electrochromic rearview mirror system is provided including an interior electrochromic rearview mirror assembly and at least one exterior electrochromic rearview mirror assembly. The interior rearview mirror assembly has an interior electrochromic reflective element that assumes a partial reflectance level in response to a first drive signal applied thereto. The exterior rearview mirror assembly has an exterior electrochromic reflective element that assumes a partial reflectance level in response to a second drive signal applied thereto. A drive circuit is provided that supplies a first drive signal to the interior electrochromic reflective element and a second drive signal to the exterior electrochromic reflective element. The drive circuit variably controls a relationship between the partial reflectance levels of the interior reflective element and the exterior electrochromic reflective element by a control signal. The interior electrochromic reflective element has a partial reflectance level that is greater than or equal to the partial reflectance level of the exterior electrochromic reflective element.

Claims

1. A vehicular electrochromic rearview mirror system, comprising:

an interior electrochromic rearview mirror assembly having an interior electrochromic reflective element that assumes a partial reflectance level in response to a first drive signal applied thereto;

at least one exterior electrochromic rearview mirror assembly having an exterior electrochromic reflective element that assumes a partial reflectance level in response to a second drive signal applied thereto; and

a drive circuit supplying a first drive signal to said interior electrochromic reflective element and a second drive signal to said exterior electrochromic reflective element, said drive circuit variably controlling a relationship between the partial reflectance levels of said interior electrochromic reflective element and said exterior electrochromic reflective element by a control signal, whereby said interior electrochromic reflective element has a partial reflectance level that is greater than or equal to the partial reflectance level of said exterior electrochromic reflective element.

2. The vehicular electrochromic rearview mirror system in claim 1 wherein said control signal comprises a pulse width modulated signal.

3. The vehicular electrochromic rearview mirror system in claim 2 wherein said drive circuit comprises a microcontroller.

4. The vehicular electrochromic rearview mirror system in claim 2 including a proportional controller supplying one of said drive signals.

5. The vehicular electrochromic rearview mirror system in claim 1 wherein said at least one electrochromic exterior rearview mirror comprises a driver-side exterior rearview mirror and a passenger-side rearview mirror.

6. The vehicular electrochromic rearview mirror system in claim 1 including a proportional controller supplying one of said drive signals.

7. The vehicular electrochromic rearview mirror system in claim 1 wherein said first drive signal is supplied from a circuit comprising a first electronic switch and said second drive signal is supplied from another circuit comprising a second electronic switch.

8. The vehicular electrochromic rearview mirror system in claim 7 including a microcontroller operating said first electronic switch at a first repetition rate and said second electronic switch at a second repetition rate.

9. The vehicular electrochromic rearview mirror system in claim 8 wherein one said repetition rate is at a high end of human hearing frequencies and another said repetition rate is at a low end of human hearing frequencies.

10. The vehicular electrochromic rearview mirror system in claim 9 wherein said second repetition rate is at a high end of human hearing frequencies and said first repetition rate is at a low end of human hearing frequencies.

11. The vehicular electrochromic rearview mirror system in claim 8 wherein said microcontroller operates said second electronic switch during steady-state reflectance levels at a duty cycle of less than or equal to 65%.

12. The vehicular electrochromic rearview mirror system in claim 11 wherein said microcontroller operates said first electronic switch during steady-state reflectance levels at a duty cycle greater than or equal to 65%.

13. The vehicular electrochromic rearview mirror system in claim 12 wherein said microcontroller operates said second electronic switch during steady-state reflectance levels at a duty cycle in a range of between 0% and 50%.

14. The vehicular electrochromic rearview mirror system in claim 13 wherein said microcontroller operates said first electronic switch during steady-state reflectance levels at a duty cycle in a range of between 75% and 100%.

15. The vehicular electrochromic rearview mirror system in claim 7 wherein said first and second electronic switches are comprised of transistors.

16. The vehicular electrochromic rearview mirror system in claim 7 wherein said first and second electronic switches comprise one of a bipolar transistor and a field-effect transistor.

17. The vehicular electrochromic rearview mirror system in claim 7 wherein said first and second electronic switches are operated in saturated modes.

18. The vehicular electrochromic rearview mirror system in claim 7 wherein said drive circuit monitors voltage across at least one of said reflective elements and controls at least one of said first and second switches at least in part as a function of monitored voltage.

19. The vehicular electrochromic rearview mirror system in claim 7 wherein said drive circuit monitors voltage across said interior electrochromic reflective elements and controls said first electronic switch at least in part as a function of the monitored voltage.

20. The vehicular electrochromic rearview mirror system in claim 19 wherein said drive circuit monitors voltage across said exterior electrochromic reflective elements and controls said second electronic switch at least in part as a function of the monitored voltage.

21. The vehicular electrochromic rearview mirror system in claim 7 wherein said drive circuit monitors voltage across said exterior electrochromic reflective elements and controls said second electronic switch at least in part as a function of the monitored voltage.

22. The vehicular electrochromic rearview mirror system in claim 1 wherein said drive circuit comprises a switching power supply.

23. The vehicular electrochromic rearview mirror system in claim 22 wherein said switching power supply comprises an impedance device and an electronic switch in series electrical connection between the associated one of said electrochromic reflective elements and a voltage potential.

24. The vehicular electrochromic rearview mirror system in claim 23 wherein said impedance device has energy storing capability.

25. The vehicular electrochromic rearview mirror system in claim 23 wherein said impedance device comprises an inductor.

26. The vehicular electrochromic rearview mirror system in claim 23 wherein said voltage potential comprises a voltage in the range from 5 volts DC to 16 volts DC.

27. The vehicular electrochromic rearview mirror system in claim 26 wherein said voltage potential comprises a voltage of approximately 8 volts DC.

28. A vehicular electrochromic rearview mirror system, comprising:

an interior electrochromic rearview mirror assembly having an interior electrochromic reflective element that assumes a partial reflectance level in response to a voltage applied thereto;

at least one exterior electrochromic rearview mirror assembly having an exterior electrochromic reflective element that assumes a partial reflectance level in response to a second voltage applied thereto; and

a digital drive circuit comprising a microcontroller, said digital drive circuit supplying a first voltage to said interior electrochromic reflective element and a second voltage to said exterior electrochromic reflective element, said first voltage being no greater than said second voltage, whereby said interior electrochromic reflective element has a partial reflectance level that is greater than or equal to the partial reflectance level of said exterior electrochromic reflective element, and wherein said microcontroller supplies a pulse width modulated signal controlling a proportion between said first and second voltages.

29. The vehicular electrochromic rearview mirror system in claim 28 wherein said at least one electrochromic exterior rearview mirror comprises a driver-side exterior rearview mirror and a passenger-side rearview mirror.

30. The vehicular electrochromic rearview mirror system in claim 28 including a proportional controller supplying one of said drive signals as a function of said pulse width modulated signal.

31. The vehicular electrochromic rearview mirror system in claim 28 wherein said first voltage is supplied from a circuit comprising a first electronic switch and said second voltage is supplied from another circuit comprising a second electronic switch.

32. The vehicular electrochromic rearview mirror system in claim 31 wherein said microcontroller operates said first electronic switch at a first repetition rate and said second electronic switch at a second repetition rate.

33. The vehicular electrochromic rearview mirror system in claim 32 wherein one said repetition rate is at a high end of human hearing frequencies and another said repetition rate is at a low end of human hearing frequencies.

34. The vehicular electrochromic rearview mirror system in claim 33 wherein said second repetition rate is at a high end of human hearing frequencies and said first repetition rate is at a low end of human hearing frequencies.

35. The vehicular electrochromic rearview mirror system in claim 32 wherein said microcontroller operates said second electronic switch during steady-state reflectance levels at a duty cycle of less than or equal to 65%.

36. The vehicular electrochromic rearview mirror system in claim 35 wherein said microcontroller operates said first electronic switch during steady-state reflectance levels at a duty cycle greater than or equal to 65%.

37. The vehicular electrochromic rearview mirror system in claim 36 wherein said microcontroller operates said second electronic switch during steady-state reflectance levels at a duty cycle in a range of between 0% and 50%.

38. The vehicular electrochromic rearview mirror system in claim 37 wherein said controller operates said first electronic switch during steady-state reflectance levels at a duty cycle in a range of between 75% and 100%.

39. The vehicular electrochromic rearview mirror system in claim 31 wherein said first and second electronic switches are comprised of transistors.

40. The vehicular electrochromic rearview mirror system in claim 39 wherein said first and second electronic switches comprise one of a bipolar transistor and a field-effect transistor.

41. The vehicular electrochromic rearview mirror system in claim 31 wherein said first and second electronic switches are operated in saturated modes.

42. The vehicular electrochromic rearview mirror system in claim 31 wherein said digital drive circuit monitors voltage across at least one of said reflective elements and controls at least one of said first and second switches at least in part as a function of monitored voltage.

43. The vehicular electrochromic rearview mirror system in claim 31 wherein said digital drive circuit monitors voltage across said interior electrochromic reflective elements and controls said first electronic switch at least in part as a function of the monitored voltage.

44. The vehicular electrochromic rearview mirror system in claim 43 wherein said drive circuit monitors voltage across said exterior electrochromic reflective elements and controls said second electronic switch at least in part as a function of the monitored voltage.

45. The vehicular electrochromic rearview mirror system in claim 31 wherein said drive circuit monitors voltage across said exterior electrochromic reflective elements and controls said second electronic switch at least in part as a function of the monitored voltage.

46. The vehicular electrochromic rearview mirror system in claim 28 wherein said digital drive circuit comprises a switching power supply.

47. The vehicular electrochromic rearview mirror system in claim 46 wherein said switching power supply comprises an impedance device and an electronic switch in series electrical connection between the associated one of said electrochromic reflective elements and a voltage potential.

48. The vehicular electrochromic rearview mirror system in claim 47 wherein said impedance device has energy storing capability.

49. The vehicular electrochromic rearview mirror system in claim 47 wherein said impedance device comprises an inductor.

50. The vehicular electrochromic rearview mirror system in claim 47 wherein said voltage potential comprises a voltage in the range from 5 volts DC to 16 volts DC.

51. The vehicular electrochromic rearview mirror system in claim 50 wherein said voltage potential comprises a voltage of approximately 8 volts DC.

52. A vehicular electrochromic rearview mirror system, comprising:

an interior electrochromic rearview mirror assembly having an interior electrochromic reflective element that assumes a partial reflectance level in response to a first drive signal applied thereto;

a first exterior electrochromic rearview mirror assembly having a first exterior electrochromic reflective element that assumes a partial reflectance level in response to a second drive signal applied thereto;

a second exterior electrochromic rearview mirror assembly having a second exterior electrochromic reflective element that assumes a partial reflectance level in response to a third drive signal applied thereto; and

a digital drive circuit comprising a microcontroller, said digital drive circuit supplying a first drive signal to said interior electrochromic reflective element, a second drive signal to said first exterior electrochromic reflective element and a third drive signal to said second exterior electrochromic reflective element, said digital drive circuit variably controlling a relationship among the partial reflectance levels of said interior electrochromic reflective element, said first exterior electrochromic reflective element and said second exterior electrochromic reflective element by at least first and second pulse width modulated control signals.

53. The vehicular electrochromic rearview mirror system in claim 52 wherein said first electrochromic exterior rearview mirror comprises a driver-side exterior rearview mirror and said second electrochromic exterior rearview mirror comprises a passenger-side rearview mirror.

54. The vehicular electrochromic rearview mirror system in claim 52 including a first proportional controller supplying one of said drive signals as a function of said first pulse width modulated signal and a second proportional controller supplying another of said drive signals as a function of said second pulse width modulated signal.

55. The vehicular electrochromic rearview mirror system in claim 52 wherein said first drive signal is supplied from a first circuit comprising a first electronic switch, said second drive signal is supplied from a second circuit comprising a second electronic switch and said third drive signal is supplied from a third circuit comprising a third electronic switch.

56. The vehicular electrochromic rearview mirror system in claim 55 wherein said microcontroller operates said first electronic switch at a first repetition rate, said second electronic switch at a second repetition rate and said third electronic switch at a third repetition rate.

57. The vehicular electrochromic rearview mirror system in claim 56 wherein said microcontroller operates at least one of said second and third electronic switches during steady-state reflectance levels at a duty cycle of less than or equal to 65%.

58. The vehicular electrochromic rearview mirror system in claim 57 wherein said microcontroller operates at least said first electronic switch during steady-state reflectance levels at a duty cycle greater than or equal to 65%.

59. The vehicular electrochromic rearview mirror system in claim 58 wherein said microcontroller operates said at least one of said second and third electronic switches during steady-state reflectance levels at a duty cycle in a range of between 0% and 50%.

60. The vehicular electrochromic rearview mirror system in claim 59 wherein said controller operates at least said first electronic switch during steady-state reflectance levels at a duty cycle in a range of between 75% and 100%.

61. The vehicular electrochromic rearview mirror system in claim 56 wherein said digital drive circuit monitors voltage across said interior electrochromic reflective element and controls said first electronic switch at least in part as a function of the monitored voltage.

62. The vehicular electrochromic rearview mirror system in claim 55 wherein said first, second and third electronic switches are comprised of transistors.

63. The vehicular electrochromic rearview mirror system in claim 62 wherein said first, second and third electronic switches comprise one of a bipolar transistor and a field-effect transistor.

64. The vehicular electrochromic rearview mirror system in claim 55 wherein said first, second and third electronic switches are operated in saturated modes.

65. The vehicular electrochromic rearview mirror system in claim 64 wherein said drive circuit monitors voltage across said first exterior electrochromic reflective element and controls said second electronic switch at least in part as a function of the monitored voltage.

66. The vehicular electrochromic rearview mirror system in claim 55 wherein said digital drive circuit monitors voltage across at least one of said reflective elements and controls at least one of said first, second and third switches at least in part as a function of monitored voltage.

67. The vehicular electrochromic rearview mirror system in claim 66 wherein said drive circuit monitors voltage across said second exterior electrochromic reflective element and controls said third electronic switch at least in part as a function of the monitored voltage.

68. The vehicular electrochromic rearview mirror system in claim 52 wherein said digital drive circuit comprises a switching power supply.

69. The vehicular electrochromic rearview mirror system in claim 68 wherein said switching power supply comprises an impedance device and an electronic switch in series electrical connection between the associated one of said electrochromic reflective elements and a voltage potential.

70. The vehicular electrochromic rearview mirror system in claim 69 wherein said impedance device has energy storing capability.

71. The vehicular electrochromic rearview mirror system in claim 70 wherein said impedance device comprises an inductor.

72. The vehicular electrochromic rearview mirror system in claim 69 wherein said voltage potential comprises a voltage in the range from 5 volts DC to 16 volts DC.

73. The vehicular electrochromic rearview mirror system in claim 72 wherein said voltage potential comprises a voltage of approximately 8 volts DC.