METHOD FOR ELECTRICALLY CONTROLLING A FUNCTIONAL ELEMENT ENCLOSED IN A GLAZING UNIT

Abstract

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.

Claims

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 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 has means for temporarily storing energy outputted by the at least one functional element.

2. The method according to claim 1, wherein the electrical voltage is changed by pulse width modulation.

3. The method according to claim 1, wherein energy temporarily stored in the control unit is used for charging the at least one functional element.

4. The method according to claim 1, wherein the control unit has a capacitor for temporarily storing energy transferred by the at least one functional element.

5. The method according to claim 1, wherein the control unit has an LC filter and an output transistor.

6. The method according to claim 1, wherein the control unit has an inductance that is electrically connected to a terminal on a flat electrode and, with a second terminal, the inductance is connected in each case to an input of a switch.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. A vehicle comprising a glazing assembly according to claim 11.

13. A method comprising providing the glazing assembly according to claim 11 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.

14. 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.

15. The method according to claim 5, wherein the an output transistor is a field-effect transistor (FE)T or thyristor.

16. The method according to claim 6, wherein the switch is a transistor.

17. The method according to claim 13, wherein the vehicle is a motor vehicle.

18. The method according to claim 13, wherein the glazing assembly is a windshield, a rear window, a side window, and/or a roof panel.

Description

[0044] They depict:

[0045] FIG. 1 a schematic representation of a glazing assembly,

[0046] FIG. 2 a cross-sectional representation of a first thermoplastic layer with a functional element with an electrical terminal,

[0047] FIG. 3 a graphic representation of a profile of an electrical voltage applied to the functional element in accordance with the method according to the invention,

[0048] FIG. 4 a switching device for implementing the method according to the invention,

[0049] FIG. 5 an exemplary embodiment of a switching device for operating the functional element in accordance with the method,

[0050] FIG. 6 a profile of a voltage V.sub.PDLC1 and a profile of a voltage V.sub.PDLC2,

[0051] FIG. 7 a profile of a voltage V.sub.PDLC, and

[0052] FIG. 8 an equivalent circuit diagram of the functional element.

[0053] In the exemplary embodiments, the components described represent features of the invention, in each case independently of one another, that are also to be regarded as part of the invention in isolation or even in a combination different from that depicted.

[0054] Specifications with numerical values are generally not to be understood as exact values, but also include a tolerance of ±1% up to ±10%.

[0055] FIG. 1 depicts a schematic representation of a glazing assembly 100 with a glazing unit 1, which can be installed, for example, in a motor vehicle or in a building. The glazing unit 1 comprises an outer pane 1a and an inner pane 1b that are joined to one another via an intermediate layer 3. The outer pane 1a has a thickness of 2.1 mm and is made of soda lime glass. The inner pane 1b has a thickness of 1.6 mm and is made of clear soda lime glass.

[0056] The glazing unit 1 is equipped in a central region with the functional element 2 that is enclosed in the intermediate layer 3. The intermediate layer 3 comprises a total of three thermoplastic layers, formed in each case by a thermoplastic film with a thickness of 0.38 mm made of PVB. The first thermoplastic layer 3a is bonded to the outer pane 1; the second thermoplastic layer 3b, to the inner pane 1b. The intervening third thermoplastic layer surrounds the cut-to-size functional element 2 (PDLC multilayer film) substantially flush on all sides. The functional element 2 is thus embedded all around in thermoplastic material and protected thereby.

[0057] FIG. 1 further depicts the switched-on state of the glazing assembly 100 with the functional element 2 enclosed in the glazing unit 1. The glazing assembly 100 also includes a control unit 11 (also called an ECU in a motor vehicle), which is electrically connected to the functional element 2 via a closed switch 12, a flat conductor, electrical terminals 13 (FIG. 2), and bus bars 8 such that an electrical voltage V.sub.PDLC can be applied on the terminals 13.

[0058] The optical properties of the glazing unit 1 are controlled by the control unit 11. For this purpose, the control unit 11 is electrically connected to two transparent flat electrodes 10 of the functional element 2. An electrical voltage V.sub.PDLC is applied between the flat electrodes 10 by the control unit 11 and the polarity of the voltage V.sub.PDLC is changed periodically (alternated). The voltage V.sub.PDLC has a trapezoidal profile, in accordance with FIG. 3.

[0059] FIG. 2 depicts a cross-sectional representation of a first thermoplastic layer 3a with a functional element 2 with an electrical terminal 13. In this embodiment, the first thermoplastic layer 3a is a PVB film with a thickness of 0.38 mm.

[0060] The functional element 2 is a multilayer film composed of an active layer 9, two flat electrodes 10, and two carrier films 11. Such multilayer films are commercially available as PDLC multilayer films. The active layer 9 is arranged between the two flat electrodes 10. The active layer 9 contains a polymer made with liquid crystals dispersed therein, which align themselves as a function of the electrical voltage applied on the flat electrodes 10, by which means the optical properties can be controlled. The carrier films 11 are made of PET and have a thickness of approx. 0.125 mm. The carrier films 11 are provided with a coating of ITO with a thickness of approx. 100 nm facing the active layer, which form the flat electrodes 10.

[0061] The flat electrodes 10 can be connected to an electrical voltage via electrically conductive bus bars 8. Here, the bus bars 8 are formed by a silver-containing screen print. Alternatively, the bus bars can be formed by electrically conductive metal strips or an electrically conductive coating. Here, “metal” (copper) includes metal alloy (copper alloy). One bus bar 8 is connected to the flat electrode 10, by recessing the carrier film 11, a flat electrode 10, and the active layer along an edge region of the respective side of the functional element 2 such that the other opposite flat electrode 10 with the associated carrier film 11 protrudes. The respective bus bar 8 is arranged on the protruding flat electrode 10.

[0062] Two conductor wires connect the bus bars 8 to an electrical voltage V.sub.PDLC via a flat conductor in each case. Here, one conductor wire is electrically conductively connected to a terminal region of the flat conductor in each case. In addition, an electrically conductive connection can be reinforced by a solder connection between a conductor wire and a terminal region 13 in each case.

[0063] FIG. 3 shows a graphic representation of a profile of an electrical voltage V.sub.PDLC applied to the functional element 2. In this example, the voltage V.sub.PDLC was applied to the functional element 2.

[0064] The applied electrical voltage V.sub.PDLC is an AC voltage. The control unit 11 generates the voltage V.sub.PDLC with a trapezoidal profile. The frequency of the voltage is preferably 50 Hz with an effective voltage of 48 V. The trapezoidal shape has a falling slope, marked in FIG. 3, of approx. 5% of the period duration in order to lengthen the discharge phase of the functional element. The voltage profile shown in FIG. 3 was applied to the functional element 2 as follows: [0065] a) an increasing electrical voltage for charging the functional element 2, with the electrical voltage increasing to a first peak value, [0066] b) the electrical voltage was reduced to a final voltage of 0 V for discharging the functional element 2, [0067] c) the functional element 2 was charged with reversed polarity as in step a) with an rising electrical voltage, with the electrical voltage increasing to a second peak value, [0068] d) the electrical voltage was reduced to the final voltage of 0 V for discharging the functional element 2, and [0069] the steps a) through d) were repeated periodically.

[0070] FIG. 4 depicts a circuit diagram of an embodiment of a first half bridge with a downstream LC filter (L1, C2) at the time of the discharging of the functional element 2. Another second half bridge shown in FIG. 5 is necessary for operating the functional element.

[0071] By means of the LC filter (L1, C2) and a pulse width modulation PWM, the flat electrodes 10 are discharged with a delay immediately when the polarity is switched. The duty cycle of the PWM is decisive for the discharge time. For this purpose, an inductance, for example, coil L1, is provided in the control unit 11. The coil L1 is wired with one terminal to a flat electrode 10. With its second terminal, the coil L1 is connected to an input of a switch in each case, e.g., of a transistor (FET, thyristor, or MOSFET), Q1 and Q2. With its output, the transistor Q1 is connected to ground. The output of the transistor Q2 is connected to the first terminal of a capacitor C1 as capacitance. The voltage Vgs between the gate and source of the transistor is 0 V. The transistor Q1 can be switched by means of the pulse width modulation PWM to an electrically conductive state. A second terminal of the capacitor C1 is connected to ground. The capacitor C1 serves as temporary storage. A capacitor C2 capacitively connects the flat electrode 10 to the ground potential. The circuit shown in FIG. 4 can be operated as a half bridge with an LC filter.

[0072] To switch on transparency in the glazing unit 1, the control unit 11 generates the electrical voltage V.sub.PDLC at the electrical terminal 13. The control unit 11 can generate the electrical voltage V.sub.PDLC as AC voltage with a trapezoidal profile, as shown by way of example in FIG. 3. After the functional element 2 has been charged to 48 V, the transistor Q1 is switched with a PWM signal. While the transistor Q1 switches, a current flows from the functional element 2 (PDLC) via the coil L1 and the transistor Q1 to the potential GND (ground potential).

[0073] As soon the transistor Q1 is switched off and no current can flow via the transistor Q1, the coil L1 counteracts this such that the current continues to flow via the transistor Q2 into a capacitor C1. This increases the voltage across the capacitor C1. The energy stored in the capacitor C1 can be used as additional electrical energy for the next charging of the functional element 2 and will not dissipate as reactive power in the form of heat energy as in a conventional control unit. This result was unexpected and surprising for the person skilled in the art.

[0074] FIG. 5 depicts a switching device for operating the functional element 2. The switching device comprises the first half bridge, shown in FIG. 4, consisting of transistor Q11 and transistor Q21 with a downstream LC filter L11, C21 as well as a second half bridge. The second half bridge comprises the transistor Q12 and the transistor Q22 with a downstream LC filter L12, C22. Analogously to FIG. 4, the transistor Q11 is switched by means of PWM1 to an electrically conductive state.

[0075] The voltage V.sub.PDLC, in particular AC voltage, applied to the functional element 2 is generated, by the two half bridges, which switch anti-cyclically between 0 V and an intermediate circuit voltage V.sub.C1. The intermediate circuit voltage V.sub.C1 is applied to the capacitor C1. The negative voltage “sees” only the functional element 2, since it is connected between the two outputs of the two half bridges.

[0076] The state (Vgs=0 V at Q2, PWM at Q1) shown in FIG. 4 applies only to the falling edge of the respective half bridge.

[0077] FIG. 6 through 8 illustrate the generation of the electrical voltage V.sub.PDLC applied to the functional element 2. FIG. 6 shows a profile of a voltage V.sub.PDLC1, which is applied to the output of the first half bridge, as shown in FIG. 5. Furthermore, FIG. 6 shows the profile of a voltage V.sub.PDLC2, which is applied to the output of the second half bridge. Both the voltage V.sub.PDLC1 and the voltage V.sub.PDLC2 have trapezoidal profiles. FIG. 7 shows a voltage difference of the voltages V.sub.PDLC1 and V.sub.PDLC2 as voltage V.sub.PDLC. FIG. 8 depicts an equivalent circuit diagram of the functional element 2. A capacitance C.sub.PDLC represents the functional element 2, on which the electrical voltage V.sub.PDLC, as a difference of the voltages V.sub.PDLC1 and V.sub.PDLC2, is applied.

LIST OF REFERENCE CHARACTERS

[0078] 1 glazing unit [0079] 1a outer pane [0080] 1b inner pane [0081] 2 functional element [0082] 3 intermediate layer [0083] 3a first thermoplastic layer [0084] 3b second thermoplastic layer [0085] 7 carrier film [0086] 8 bus bar [0087] 9 active layer [0088] 10 flat electrodes [0089] 11 control unit [0090] 12 switch [0091] 13 electrical terminal [0092] 100 glazing assembly [0093] C1 capacitor [0094] C2, C21, C22 capacitor [0095] D1 diode [0096] L1, L11, L12 coil [0097] Q1, Q11, Q12 transistor [0098] Q2, Q21, Q22 transistor [0099] V.sub.PDLC, V.sub.PDLC1, V.sub.PDLC2 electrical voltage