Controller, system and method for controlling the state of liquid crystal-based switchable windows

Patent metadata

Field	Value
Publication number	US-12049786-B2
Application number	US-202017631921-A
Country	US
Kind code	B2
Filing date	Jul 30, 2020
Priority date	Aug 2, 2019
Publication date	Jul 30, 2024
Grant date	Jul 30, 2024

Abstract

A method for controlling the state of two or more liquid crystal-based switchable windows includes in a first step providing correction data which define a relationship between a state signal and an output voltage level. The correction data is provided for each of the switchable windows and the state of the switchable windows may be adjusted according to the state signal between a minimum and maximum level. In a subsequent step, the state signal is provided which defines the desired state of one or more selected switchable windows. In a further step, a required voltage level is determined for setting the desired state based on the state signal and the respective correction data for each of the one or more selected windows. In a subsequent step d), an AC output voltage is generated having the required voltage level for each of the one or more selected windows.

First claim

The invention claimed is:

1. A method for controlling the state of two or more liquid crystal-based switchable windows ( 30 ) comprising:
providing correction data which defines a relationship between a state signal which defines the desired state and an output voltage level which defines the output voltage required to set the desired state, wherein the correction data is provided for each of the two or more switchable windows ( 30 ) and wherein the state of the switchable windows ( 30 ) may be adjusted according to the state signal between a minimum level and a maximum level,
providing the state signal which defines the desired state of one or more selected windows of the two or more switchable windows ( 30 ),
determining a required voltage level for setting the desired state based on the state signal and the respective correction data for each of the one or more selected windows, and
generating an AC output voltage having the required voltage level for each of the one or more selected windows,
wherein an output terminal for outputting the AC voltage is monitored for a DC offset and if a DC offset is detected, a DC bias of the AC output voltage is adjusted in order to control the DC offset at the output terminal to a target value of zero.

2. The method according to claim 1 , wherein the state signal is provided as an analogue input signal.

3. The method according to claim 1 , wherein the state is a tint level which defines the transmission of visible light through the respective switchable window ( 30 ).

4. The method according to claim 3 , wherein the state signal is provided in dependence on a received alarm signal, wherein
in case an alarm signal indicating a fire alarm is received a state signal corresponding to a minimum tint level is provided for all switchable windows ( 30 ),
in case an alarm signal indicating a rampage situation is received a state signal corresponding to a maximum tint level and/or a maximum haze level is provided for all switchable windows ( 30 ), and
in case an alarm signal indicating a bird flying in close proximity to a switchable window ( 30 ) is received a state signal corresponding to maximum tint level and/or a maximum haze level for the respective switchable window ( 30 ) is provided.

5. The method according to claim 1 , wherein the state signal is provided in dependence on one or more data sources selected from the group comprising interior photo sensors, exterior photo sensors, clocks, calendars, connections to communication devices, radar sensors, bird detection devices, interior temperature sensors, exterior temperature sensors, user input devices, noise sensors, room occupation sensors, power consumption sensors and historical climate databases.

6. The method according to claim 1 , wherein providing of the state signal takes into account the position of the respective switchable window ( 30 ) in a façade of a building and a desired pattern.

7. The method according to claim 1 , wherein the correction data is provided in form of parameters for a mathematical function and/or in form of a look-up table.

8. The method according to claim 1 , wherein the provided correction data is selected such that the resulting output voltages cause each of the two or more switchable windows ( 30 ) to switch to essentially the same state for the same state signal.

9. The method according to claim 1 , wherein phases of at least two AC output voltages are shifted with respect to each other.

10. The method according to claim 9 , wherein AC output voltages for N of the two or more switchable windows ( 30 ) are provided, and wherein the AC output voltage for the n-th window is phase shifted by an amount of (n−1)*(2π)/N for n from 1 to N.

11. The method according to claim 1 , wherein the AC output voltage is a square wave AC voltage.

12. The method according to claim 1 , wherein a charging current flows to the respective switchable window ( 30 ) for a rising edge of the AC output voltage and a discharge current flows from the respective switchable window ( 30 ) for a falling edge of the AC output voltage, and electrical energy is recuperated during the falling edge of the AC output voltage.

13. A controller ( 20 ) for controlling the state of two or more liquid crystal-based switchable windows ( 30 ) comprising a storage memory for storing correction data for each of the two or more switchable windows ( 30 ), an input port for receiving a state signal which defines the desired state of one or more selected windows of the two or more switchable windows ( 30 ), a processor configured to generate a driving signal for each of the switchable windows ( 30 ) in dependence on the state signal and the respective correction data and amplifiers for each of the two or more switchable windows ( 30 ) for amplifying the driving signal and for providing an AC output voltage for each of the switchable windows ( 30 ), wherein the controller ( 20 ) is configured to execute the method according to claim 1 .

14. The controller ( 20 ) according to claim 13 , wherein the amplifiers are configured as four quadrant buck converters and the controller additionally comprises a DC-buffer for storing recuperated energy.

15. A building management system ( 100 ) for controlling the state of two or more switchable windows ( 30 ) comprising one or more controllers ( 20 ) according to claim 13 , a control unit ( 110 ) and a communication module ( 10 ), wherein the communication module ( 10 ) and the one or more controllers ( 20 ) are adapted to communicate by means of a first communication protocol and the communication module ( 10 ) is further adapted to communicate by means of a second communication protocol with the control unit ( 110 ).

16. A system comprising the building management system ( 100 ) according to claim 15 and two or more liquid crystal-based switchable windows ( 30 ), wherein the two or more liquid crystal-based switchable windows ( 30 ) are connected to the building management system ( 100 ).

17. The method according to claim 1 , wherein the state signal is provided in form of a digital signal.

18. The method according to claim 1 , wherein the state is s a scattering level which defines the haze of the respective switchable window ( 30 ).

19. The method according to claim 1 , wherein the AC output voltage is a trapezoid wave AC voltage.

Assignees

• Merck Patent Gmbh

Inventors

• Christ Heiko
• Nie Chuan
• De Jong Ties
• Van Den Muijsenberg Jasper

Classifications

• G02F1/13306

  Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence) · CPC title

• E06B2009/2464

  featuring transparency control by applying voltage, e.g. LCD, electrochromic panels · CPC title

• G09G3/36

  using liquid crystals · CPC title

• G09G2320/0276

  for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction · CPC title

• G02F1/13756

  the liquid crystal selectively assuming a light-scattering state (G02F1/1334, G02F1/13718 take precedence) · CPC title