Digital electrochromic mirror sytem
First Claim
1. An electrochromic rearview mirror assembly for a vehicle, comprising:
- an electrochromic reflective element having an electrochromic cell, wherein said reflective element colors to a partial reflectance level in response to a drive signal applied to said electrochromic cell; and
a drive circuit which applies a pulsed drive signal to said electrochromic cell in order to establish said partial reflectance level of said reflective element, said drive circuit controlling said partial reflectance level at least as a function of the duty cycle of said pulsed drive signal.
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Abstract
An electrochromic rearview mirror system for a vehicle includes an electrochromic reflective element having an electrochromic cell, wherein the reflective element colors to a partial reflectance level in response to a drive signal applied to the cell. The rearview mirror assembly additionally includes a drive circuit which applies a pulsed drive signal to the electrochromic cell in order to establish the partial reflectance level of the reflective element. The drive circuit controls the partial reflectance level as a function of the duty cycle of the pulsed drive signal, which has a pulse repetition rate of at least approximately 10 cycles per second and preferably at least approximately 20 cycles per second. The drive circuit additionally adjusts the amplitude of the pulses as a function of the voltage developed across the electrochromic cell.
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Citations
49 Claims
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1. An electrochromic rearview mirror assembly for a vehicle, comprising:
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an electrochromic reflective element having an electrochromic cell, wherein said reflective element colors to a partial reflectance level in response to a drive signal applied to said electrochromic cell; and
a drive circuit which applies a pulsed drive signal to said electrochromic cell in order to establish said partial reflectance level of said reflective element, said drive circuit controlling said partial reflectance level at least as a function of the duty cycle of said pulsed drive signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An electrochromic rearview mirror assembly for a vehicle, comprising:
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an electrochromic reflective element having an electrochromic cell, wherein said reflective element colors to a partial reflectance level in response to a drive signal applied to said electrochromic cell; and
a drive circuit which applies a drive signal to said electrochromic cell in order to establish the partial reflectance level of said reflective element, said drive circuit including a source, a digital controller, a switching device responsive to an output of said controller for applying said source to said electrochromic cell and an input of said controller responsive to the voltage developed across said electrochromic cell by said source, wherein said digital controller monitors the voltage developed across said electrochromic cell, adjusts said source, and closes and opens said switching device according to a particular duty cycle in order to control said partial reflectance level. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. An electrochromic rearview mirror assembly for a vehicle, comprising:
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an electrochromic reflective element having an electrochromic cell, wherein said reflective element colors to a partial reflectance level in response to a drive signal applied to said electrochromic cell; and
a drive circuit which applies a drive signal to said electrochromic cell in order to establish the partial reflectance level of said reflective element, said drive circuit including a digital controller, a first switching device responsive to an output of said controller for applying a source to said electrochromic cell and a second switching device responsive to an output of said controller for draining charge from said electrochromic cell, wherein said controller alternatingly closes said switching devices according to a particular duty cycle in order to control said partial reflectance level at least as a function of said duty cycle, wherein said digital controller closes and opens said switching devices at a repetition rate of at least approximately 10 cycles per second. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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Specification