Source: https://patents.google.com/patent/US5973818A/en
Timestamp: 2019-01-23 07:54:05
Document Index: 131120919

Matched Legal Cases: ['application No. 09', 'application No. 09', 'application No. 09', 'application No. 09', 'application No. 09', 'application No. 09']

US5973818A - Method and apparatus for controlling an electrochromic device - Google Patents
Method and apparatus for controlling an electrochromic device Download PDF
US5973818A
US5973818A US09157723 US15772398A US5973818A US 5973818 A US5973818 A US 5973818A US 09157723 US09157723 US 09157723 US 15772398 A US15772398 A US 15772398A US 5973818 A US5973818 A US 5973818A
US09157723
A method and concomitant apparatus for use in an electrochromic control system in which components causing the charging and discharging of an electrochromic device are subject to drift errors and other errors. In the case of such errors, the actual programming level and the desired programming level as indicated by, e.g., a count value, may diverge. The invention periodically determines the actual programming level of the electrochromic device and responsively adjusts a parameter representative of the desired programming level.
The invention comprises a method and concomitant apparatus for use in an electrochromic control system in which components causing the charging and discharging of an electrochromic device are subject to drift errors and other errors. In the case of such errors, the actual programming level and the a desired programming level as indicated by, e.g., a count value, may diverge. The invention periodically determines the actual programming level of the electrochromic device and responsively adjusts a parameter representative of the desired programming level.
FIG. 1 depicts an electrochromic control apparatus 100 including charge error correction apparatus according to the invention. The electrochromic control apparatus 100 is used to control the amount of charge imparted to an electrochromic device EC. Since the electrochromic device EC may be modeled as a non-linear passive device having an impedance dominated by a capacitive component, the electrochromic device EC is depicted in FIG. 1 as a capacitor having a first terminal and second terminal.
In response to a coloring current ICOLOR applied to the electrochromic device EC at the first terminal 1, the charge of the electrochromic device EC increases, thereby causing the device to darken. In response to a bleaching current IBLEACH the charge of the electrochromic device EC decreases, thereby causing the electrochromic device EC to lighten. One skilled in the art will readily recognize that the polarities of the coloring current ICOLOR and the bleaching current IBLEACH may be reversed, depending on the connection and type of electrochromic device EC employed.
Up/down counter 110, illustratively an N-bit counter where N is an integer value, produces at an output a digital word COUNT indicative of a desired charge level of the electrochromic device. Specifically, up/down counter 110 produces digital word COUNT having a value between 0 and 2N -1, where a value of 0 is indicative of a minimal desired charge level of an electrochromic device (i.e., transparent or fully light) and a value of 2N -1 is indicative of a maximal desired charge level of the electrochromic device (i.e., opaque or fully dark). Thus, if N=8, up/down counter 110 produces a digital word having a value between 0 and 255 (i.e., an 8-bit word). Preferably, N is on the order of 10 or 12, such that up/down counter 110 produces a digital word having a respective value between 0 and 1023 (i.e., a 10-bit word) or 0 and 4095 (i.e., a 12-bit word).
Electrochromic coloration circuit 120 comprises a transistor M1, illustratively a MOSFET, and a battery B1. The transistor M1 has an input terminal coupled to a positive terminal of the battery B1 a control terminal coupled to receive the coloration control signal C. The first terminal of the electrochromic device EC is coupled to an output terminal of the transistor M1, the second terminal of the electrochromic device EC is coupled to a negative terminal of the battery B1. In response to the coloration control signal C, the transistor M1 allows current to flow along the path ICOLOR indicated in FIG. 1, i.e., entering the first terminal of the electrochromic device EC, such that the electrochromic device EC begins to charge and, therefore, darken.
Electrochromic bleaching circuit 125 comprises a transistor M2, illustratively a MOSFET, and a battery B2. The transistor M2 has an input terminal coupled the first terminal of the electrochromic device EC, an output terminal coupled to a negative terminal of the battery B2 and a control terminal coupled to receive the bleaching control signal B. The second terminal of the electrochromic device EC is coupled to a positive terminal of the battery B2. In response to the bleaching control signal B, the transistor M2 allows current to flow along the path IBLEACH indicated in FIG. 1, i.e., exiting the first terminal of the electrochromic device EC, such that the electrochromic device EC begins to discharge and, therefore, lighten.
Timer 140, illustratively a resettable counter, is enabled to begin counting when the charge/discharge status indicator OFF provided by the control logic 115 indicates that the clear and bleach currents are both inactive. Timer 140 counts at a rate determined by the clock input CL from the oscillator 105. A timer output signal START indicates that a predetermined count value has been reached (i.e., a predetermined amount of time has elapsed). The predetermined count value (or amount of time) is associated with the amount of time required for the electrochromic device EC to reach a substantially quiescent charge state after the removal of the color or bleach current. Thus, the timer output signal START indicates that the electrochromic device EC is in a substantially quiescent charge state and that voltage measurements of the EC device will not include voltage due to the coloring current ICOLOR or the bleaching current IBLEACH causing a voltage drop across resistive components within the electrochromic device EC.
1. In a system for controlling a charge state of an electrochromic device by selectively imparting, via control logic, one of a positive charge and a negative charge to said electrochromic device in response to changes in a value representative of a desired charge state, apparatus for correcting said desired charge state representative value comprising:
an analog to digital converter, coupled to measure said charge state of said electrochromic device without significantly altering said charge state, for producing a value representative of an actual charge state of said electrochromic device;
a code converter, coupled to said analog to digital converter, for converting said actual charge state representative value into a corrected charge state representative value;
a timer, coupled to said control logic, for providing a control signal indicative of said electrochromic device achieving a substantially quiescent charge state; and
a value changer, responsive to said quiescent state indicative control signal and said corrected charge state representative value, for replacing said desired charge state representative value with said corrected charge state representative value.
an up/down counter, coupled to said control logic and said code converter, for storing said desired charge state representative value;
said value changer comprising reset circuitry within said up/down counter.
3. The apparatus of claim 1, wherein said code converter comprises a look up table.
said analog to digital converter is coupled to said timer to provide said actual charge state representative value only when said electrochromic device has achieved a substantially quiescent charge state.
said code converter is coupled to said timer to provide said corrected charge state representative value only when said electrochromic device has achieved a substantially quiescent charge state.
said reset circuitry is coupled to said timer to replace said desired charge state representative value with said corrected charge state representative value only when said electrochromic device has achieved a substantially quiescent charge state.
said apparatus is part of a eyeglasses system; and
said electrochromic device comprises a lens portion of said eyeglasses.
8. Apparatus controlling a charge level of an electrochromic device, comprising:
a charge source, for imparting a charge to said electrochromic device;
a memory, for storing a value indicative of a desired charge level;
a controller, coupled to said memory and said charge source, for adapting said imparted charge in response to said desired charge level; and
a voltage measurement unit, coupled to said electrochromic device, for measuring a voltage level of said electrochromic device and producing therefrom a voltage level indicative signal; wherein
said controller, in response to said voltage level indicative signal, calculates an actual charge level of said electrochromic device; and
if said actual charge level is different than said desired charge level stored in said memory, said controller causes said desired charge level stored in said memory to be replaced by a value indicative of said actual charge level.
said memory comprises an up/down counter;
said controller comprises control logic and a code converter, and
said voltage measurement unit comprises an analog to digital (A/D) converter.
said code converter, in response to a output signal from said A/D converter, generates an output code indicative of a value corresponding to said actual charge level of said electrochromic device; and
said up/down counter, in response to said output code, replaces a present count value with said output code value.
said A/D converter is responsive to an output signal from a timer, said timer output signal indicative of said electrochromic device being in a substantially quiescent charge state.
said apparatus is part of an eyeglasses system; and
13. In a system for controlling a charge state of an electrochromic device by selectively imparting, via control logic, one of a positive charge and a negative charge to said electrochromic device in response to changes in a value representative of a desired charge state, a method for correcting said desired charge state representative value comprising the steps of:
measuring, during a substantially quiescent state, the voltage across the electrochromic device;
relating, to said desired charge state representative value, the measured voltage level across the electrochromic device; and
replacing said desired charge state representative value with a value representative of the actual charge state of the electrochromic device.
said electrochromic device comprises a lens portion of a pair of eyeglasses.
US09157723 1998-09-21 1998-09-21 Method and apparatus for controlling an electrochromic device Expired - Fee Related US5973818A (en)
US09157723 US5973818A (en) 1998-09-21 1998-09-21 Method and apparatus for controlling an electrochromic device
PCT/US1999/019292 WO2000017705A1 (en) 1998-09-21 1999-08-20 Method and apparatus for controlling an electrochromic device
US5973818A true US5973818A (en) 1999-10-26
ID=22564995
US09157723 Expired - Fee Related US5973818A (en) 1998-09-21 1998-09-21 Method and apparatus for controlling an electrochromic device
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WO (1) WO2000017705A1 (en)
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SJURSEN, WALTER P.;GREGORY, CHRISTOPHER C.;REEL/FRAME:009470/0619