Method and means for stepwise charge control of electrochromic layers
First Claim
1. Apparatus for step-wise charge control of an electrochromic layer, said layer being in uncolored state for the condition of no charge in said layer, said layer being colored to a first state for a first charge in said layer, and said layer being colored to a second and greater colored state for a second and greater charge in said layer, said apparatus comprising:
- selectively operable means for selecting a change of layer state to one of said states regardless of the currently existing state of said layer;
said selectively operable means including comparator means responsive both to the existing state and to the selected state and having (1) a first control output for the case of the layer in the selected state being more colored than in the existing state (A<
B), (2) a second control output for the case of the layer in the selected state being less than in the existing state (A>
B);
a constant-current charging circuit connected to charge said layer in the event of a signal in said first control output;
a constant-current charge-removal circuit connected to remove charge from said layer in the event of a signal in said second control output;
first interval-timing means connected for response to said first control-output signal and connected to said charging circuit to determine a timed incremental charge in said layer in the direction of increased color development in said layer, and second interval-timing means connected for response to said second control-output signal and connected to said constant-current charge-removal circuit to determine a timed decremental removal of charge from said layer, the timed interval for a charging increment to produce a given layer-coloring increment under control of said first interval-timing means being greater than the timed interval for a corresponding decrement of charge removal to produce a corresponding color-removing decrement under control of said second interval-timing means, and said decrement of color removal being selected to be slightly in excess of the increment of layer coloring, whereby regardless of the number of selected increment-decrement cycles there will be no cyclic growth in the coloring of said layer.
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Accused Products
Abstract
In order to control the absorptance of an electrochromic layer, the invention provides a plurality of steps for establishing different levels of coloring action. Quantities of charge are supplied to and removed from the layer, via one or the other of two constant-current sources, timed with clock pulses to a forward/backward counter. For decoloring processes, smaller quantities of charge are removed from the layer than are supplied to it during a corresponding coloring process. The quantities of charge removed for decoloring processes are, however, slightly greater than the quantities of removed charge needed to reach steps having exactly the same absorptance, so that even in the case of numerous changes between the color steps, destruction of the layer is definitely avoided. Preferred fields of use are lenses, particularly eyeglass lenses, filters and dimmable mirrors, each having an applied electrochromic layer whose absorptance is controlled for step-wise change.
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Citations
17 Claims
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1. Apparatus for step-wise charge control of an electrochromic layer, said layer being in uncolored state for the condition of no charge in said layer, said layer being colored to a first state for a first charge in said layer, and said layer being colored to a second and greater colored state for a second and greater charge in said layer, said apparatus comprising:
- selectively operable means for selecting a change of layer state to one of said states regardless of the currently existing state of said layer;
said selectively operable means including comparator means responsive both to the existing state and to the selected state and having (1) a first control output for the case of the layer in the selected state being more colored than in the existing state (A<
B), (2) a second control output for the case of the layer in the selected state being less than in the existing state (A>
B);
a constant-current charging circuit connected to charge said layer in the event of a signal in said first control output;
a constant-current charge-removal circuit connected to remove charge from said layer in the event of a signal in said second control output;
first interval-timing means connected for response to said first control-output signal and connected to said charging circuit to determine a timed incremental charge in said layer in the direction of increased color development in said layer, and second interval-timing means connected for response to said second control-output signal and connected to said constant-current charge-removal circuit to determine a timed decremental removal of charge from said layer, the timed interval for a charging increment to produce a given layer-coloring increment under control of said first interval-timing means being greater than the timed interval for a corresponding decrement of charge removal to produce a corresponding color-removing decrement under control of said second interval-timing means, and said decrement of color removal being selected to be slightly in excess of the increment of layer coloring, whereby regardless of the number of selected increment-decrement cycles there will be no cyclic growth in the coloring of said layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- selectively operable means for selecting a change of layer state to one of said states regardless of the currently existing state of said layer;
Specification