Method for electrically controlling a functional element enclosed in a glazing unit
A method for electrically controlling a functional element with electrically controllable optical properties enclosed in a glazing unit includes controlling the optical properties by a control unit connected to two transparent flat electrodes of the functional element, and applying a voltage by the control unit between the flat electrodes and the polarity of the voltage is periodically changed. The voltage has a trapezoidal profile and by the control unit an increasing electrical voltage is applied for charging the functional element, the electrical voltage increasing to a first peak value, the electrical voltage is reduced from the first peak value to a final voltage for discharging the functional element, the functional element is charged with the increasing electrical voltage with reversed polarity, wherein the electrical voltage increases to a second peak value, the electrical voltage is reduced from the second peak value to the final voltage for discharging the functional element.
1 . A method for electrically controlling at least one functional element with electrically controllable optical properties enclosed in a glazing unit, the method comprising:
controlling the optical properties by a control unit, wherein the control unit is connected to at least two transparent flat electrodes of the at least one functional element,
applying an electrical voltage by the control unit between the at least two flat electrodes and periodically changing a polarity of the voltage,
wherein the electrical voltage has a trapezoidal profile, and wherein by the control unit
a) an increasing electrical voltage is applied for charging the at least one functional element, wherein the electrical voltage increases to a first peak value,
b) the electrical voltage is reduced from the first peak value to a final voltage for discharging the at least one functional element,
c) the at least one functional element is charged with the increasing electrical voltage with reversed polarity as in step a), wherein the electrical voltage increases to a second peak value,
d) the electrical voltage is reduced from the second peak value to the final voltage for discharging the at least one functional element, and
the steps a) through d) are repeated periodically, and
wherein the control unit has an accumulator for temporary energy storage and wherein in step b) and/or in step d) electrical energy is transferred from the at least one functional element to the control unit and the control unit stores energy transferred from the at least one functional element temporarily in said accumulator;
wherein the control unit includes a switching device comprising a first half-bridge circuit connected to a first of the flat electrodes and a second half-bridge circuit connected to a second of the flat electrodes, each half-bridge circuit being connected to the respective flat electrode by an LC filter including (1) a capacitor connected having a first plate connected to the respective flat electrode and a second plate connected to a ground potential and (2) an inductor coil having a first end connected to the first plate of the capacitor and the respective flat electrode;
the first half-bridge circuit further comprising a switching transistor and the accumulator, one terminal of the accumulator being connected to a second end of the inductor of the first half-bridge circuit, the switching transistor having one terminal connected to the ground potential and another terminal connected to the second end of the inductor of the first half-bridge circuit;
wherein the switching transistor switches between (1) an off state ceasing current flow to the ground potential therethrough to cause current flowing from the second end of the inductor to charge the accumulator and (2) an on state connecting the second end of the inductor to the ground potential;
wherein a pulse width modulator is used during said discharging of step b) and/or in step d) to switch the switching transistor in accordance with a duty cycle, including to said off state to cause current flowing from the second end of the inductor to charge the accumulator and thus store energy transferred from the at least one functional element temporarily in said accumulator.
2 . The method according to claim 1 , wherein the electrical voltage is changed by pulse width modulation.
3 . The method according to claim 1 , further comprising using the energy temporarily stored in the control unit for charging the at least one functional element during step (a) and/or step (c).
4 . The method according to claim 1 , wherein the accumulator is a capacitor.
5 . The method according to claim 1 , wherein the glazing unit comprises an outer pane and an inner pane that are connected to one another via a thermoplastic intermediate layer and in which the at least one functional element is enclosed.
6 . The method according to claim 1 , wherein the at least one functional element is a PDLC functional element that makes the glazing unit appear transparent at least in some regions when the voltage supply is switched on and opaque when the voltage supply is switched off.
7 . The method according to claim 1 , wherein the increasing voltage is applied for the same period of time as the period of time during which the voltage is reduced to the final voltage.
8 . The method according to claim 1 , wherein the first peak value corresponds to the voltage of 48 V and/or the final voltage is 0 V.
9 . A glazing assembly of a vehicle or building, comprising:
a glazing unit with electrically controllable optical properties, which comprises an outer pane and an inner pane that are joined to one another via a thermoplastic intermediate layer, and in which a functional element with electrically controllable optical properties is enclosed, comprising an active layer, with which transparent flat electrodes are associated on both surfaces, and
a control unit for electrically controlling the optical properties of the glazing unit according to a method in accordance with claim 1 .
10 . A vehicle comprising a glazing assembly according to claim 9 .
11 . A method comprising providing the glazing assembly according to claim 9 in a vehicle of locomotion for travel, in the air or on water, or as a functional individual article, or as a built-in part in furniture, an appliance, or a building.
12 . The method according to claim 3 , wherein, in step a) and/or step c), energy temporarily stored in the control unit is used for charging the at least one functional element.
13 . The method according to claim 5 , wherein the switching transistor is a field-effect transistor (FE) T or thyristor.
14 . The method according to claim 11 , wherein the vehicle is a motor vehicle.
15 . The method according to claim 11 , wherein the glazing assembly is a windshield, a rear window, a side window, and/or a roof panel.
16 . The method of claim 1 , wherein said one terminal of the accumulator is also connected to a second end of the inductor of the second half-bridge circuit.
17 . The method of claim 16 , wherein each half-bridge circuit comprises an additional transistor connected between the second end of the inductor of the respective half-bridge circuit and the said one terminal of the accumulator.
18 . The method of claim 16 , wherein the accumulator is a capacitor, the other terminal of the capacitor being connected to ground potential.