TECHNICAL FIELD

The present disclosure relates generally to an automotive glazing having a switchable assembly. It particularly relates to a solution for improved performance of a switchable assembly in an automotive glazing.

BACKGROUND

Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosure, or that any publication specifically or implicitly referenced is prior art.

It is known to one skilled in the art that glazing refers to any and all the glass or similar material within a structure or the installation of any piece of glass or the similar material within a sash or frame. The glass windows of an automobile are referred to as glazing. For laminated glazing, two or more layers of glass or a similar material, are fused together with an interlayer in the middle. The fusion is completed with pressure and heat and it prevents the sheets of glass or the similar material from breaking. While some pieces of glass or the similar material might end up breaking into larger pieces, those pieces will stay together with the help of the interlayer, making it shatterproof. Windshield or windscreen, backlite, sidelite, quaterlite, sunroof etc., are regarded as some instances of glazing in a vehicle. Electrically switchable glazing based on chromogenic technologies are known in the art and includes both architectural and automotive applications. Such electrically switchable glazing technologies mostly includes polymer-dispersed liquid crystal (PDLC), suspended-particle and electrochromic devices. Known in the art are automotive glazing such as a sunroof of the automobile may include switchable assembly such as a polymer-dispersed liquid crystals (PDLC) unit within the glazing. Such an automotive glazing is capable for being selectively, rather electrically turned into transparent or opaque glazing unit. Said electrically switchable liquid crystal device or PDLC unit in the sunroof will change the transparency from opaque to transparent when an electrical field is applied to it. The sunroof may include a laminated glass panel containing the PDLC unit, sandwiched between two glass or polymer substrates and interlayer. Such sunroof glazing unit may include an outer clear glass and inner glass generally referred to as privacy glass.

PDLC unit may be operated without polarizers, and they have high transparency transmission, large viewing angle, fast switching time, they do not require any surface treatment making them potentially suitable glazing for automotive applications. Transmissions levels may also be controlled in such PDLC unit. Generally, PDLC films, within a solid polymer matrix, are composed of lower molecular weight micro sized droplets of liquid crystal. These are situated between two separate transparent conducting electrodes. Reference is made to PIG. 1 that depicts a typical PDLC unit, in which at each side of a PDLC matrix, there are two bus bars, polyethylene terephthalate (PET) films, and Indium tin oxide (ITO) films. In the absence of power or electric field, PDLC film scatters lights. This renders the glazing unit opaque. When power is supplied or electric field is applied, the liquid crystal molecules are so oriented that light passes through it and consequently rendering the glazing unit as transparent. For a given application, the PDLC unit is supposed to exhibit predefined transparency based on voltage and time (for fading effects). However, the actual transparency percentage will vary due to the changes in the environment such as and not limited to changes in temperature and also by the factors associated with aging or life or service hours of the PDLC unit.

Reference is made to “Sucheol Park; Jin Who Hong (2009). Polymer dispersed liquid crystal film for variable-transparency glazing, 517(10), 3183- -3186. doi: 10.1016/j.tsf 2008.11.115” that discloses the transmission of visible light and thermal energy through variable-transparency switchable glazing can be varied. PDLC has been the most widely used variable-transparency glazing technology in the architectural and automotive industries due to its excellent optical performance, durability, and ease of processing into large-area products. However, said literature provides indication that the PDLC product is suitable for interior applications. For exterior application, the temperature stability should be improved.

Again, reference is made to KR102177914B1 that discloses a bidirectional feedback circuit device for an inverter output for a polymer dispersed liquid crystal (PDLC) driving power, capable of a bidirectional output voltage control. The bidirectional feedback circuit device for the inverter output for the PDLC driving power includes an SMPS driver unit for outputting the driving power for driving a PDLC, an output unit for supplying the driving power to the PDLC and a bidirectional feedback circuit unit connected between the SMPS driver unit and the output unit to detect the driving power applied to the output unit and provide the detected driving power as a feedback for driving the SMPS driver unit.

A further reference is made to W02017145015A1 that discloses a moving body and an antiglare system. The disclosed system has a window having variable light transmissivity, and a control circuit for controlling transmissivity. The control circuit has a first circuit, a second circuit, a third circuit, a sensor, and a calculation circuit. The first circuit outputs, to the calculation circuit, a signal for information pertaining to a location at which a passenger will sense a variation in light level. The second circuit outputs, to the calculation circuit, a signal for information pertaining to the amount of time for adapting to a variation in light level. The third circuit outputs, to the calculation circuit, a signal for information pertaining to the speed at which the moving body moves. The sensor outputs, to the calculation circuit, a signal for information pertaining to brightness intensity within the moving body. The calculation circuit outputs, to the window, a signal for gradually altering light transmissivity in accordance with the obtained signals.

Current solutions of controllers or control system for switchable assembly in glazing is based on open loop function in which the output from the controller circuitry is not corrected as per the power consumed by the system. For scenarios, where the temperature of the glass surface of the glazing increases, the power consumption will also gradually increase. It is noted that such increase in power consumption is exponential and may even go beyond the required limit for each of the level of transparency requirement or haze requirement. It is worth noting that for transparency the haze value is desired to be zero. Generally, the prior art solutions are based on an open loop control system. In such solutions, the output voltage is applied with a predetermined value of modulation index (such as pulse width modulation, PWM) where the correction does not occur if the power at output changes.

In view of the prior art solutions disclosed hitherto, there is a requirement of eliminating the existing challenges in the glazing system having switchable assembly and providing more accurate transmittance performance. SUMMARY OF THE DISCLOSURE

An object of the present invention is to provide an improved solution overcoming the drawbacks of the prior art.

Another object of the present invention is to provide an automotive glazing with an electrically switchable assembly with a stable or an improved performance solution.

Yet another object of the present invention is to provide an automotive glazing with an electrically switchable assembly having a closed loop based control system.

A further object of the present invention is to provide an automotive glazing with an electrical switchable assembly in which the voltage to the switchable assembly is controlled based on the temperature of the glazing and/or the age of the switchable assembly.

These and other objects of the invention are achieved by the following aspects of the invention. The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This presents some concept of the invention in a simplified form to a more detailed description of the invention presented later. It is a comprehensive summary of the disclosure and it is not an extensive overview of the present invention. The intend of this summary is to provide a fundamental understanding of some of the aspects of the present invention.

In an aspect of the present invention is disclosed an automotive glazing unit. Said glazing unit comprises a first substrate of glass or polymer having at least two surfaces, a second substrate of glass or polymer having at least two surfaces and one or more interlayers and an electrically switchable assembly disposed between said first and second substrates. The switchable assembly is operably controlled by a control unit and the voltage to the switchable assembly is determined by the temperature of the glazing and life of the switchable assembly for ensuring stable performance of the switchable assembly.

In another aspect of the present invention is disclosed a method of minimizing the variation between the actual haze value and desired haze value of a switching assembly integrated in an automotive glazing by applying a corrected voltage to the switching assembly. The switching assembly is operably coupled to a closed loop based control unit configured to supply the corrected voltage to the switching assembly by determining a correction component, wherein said correction component is a function of temperature of the glazing and/or a function of life of the switchable assembly. The control system would be a closed loop control system capable of monitoring the output current and with relevant current sensing hardware, it is regarded to accommodate the variation in actual current consequently adjusting the transmittance and/or haze. There is a dedicated control unit operably coupled with the PDLC film.

The significant features of the present invention and the advantages of the same will be apparent to a person skilled in the art from the detailed description that follows in conjunction with the annexed drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The following briefly describes the accompanying drawings, illustrating the technical solution of the embodiments of the present invention or the prior art, for assisting the understanding of a person skilled in the art to comprehend the invention. It would be apparent that the accompanying drawings in the following description merely show some embodiments of the present invention, and persons skilled in the art can derive other drawings from the accompanying drawings without deviating from the scope of the disclosure.

FIG. 1 illustrates a typical PDLC unit as known in the art.

FIG. 2 illustrates schematic diagram of the automotive glazing according to an embodiment of the present invention.

FIGs. 3a-3d illustrate different views of the control unit according to an embodiment of the present invention.

FIG. 4 illustrates a graphical presentation of the power consumed by the system being varied by the temperature on the glass or the substrates or the glazing as observed in the prior art.

FIGs. 5a and 5b illustrate a block diagram of the power module and the isolator module according to an embodiment of the present invention.

FIG. 6 illustrates a graphical presentation of the power consumed by the system being varied by the temperature on the glass or the substrates or the glazing according to an embodiment of the present invention.

FIG. 7 illustrates a graphical presentation of a sample data set that shows the effect of light transmittance (TL) and haze measurements with respect to temperatures according to an embodiment of the present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the disclosure.

DETAILED DESCRIPTION

The present disclosure is now discussed in more detail referring to the drawings that accompany the present application. It would be appreciated by a skilled person that this description to assist the understanding of the invention but these are to be regarded as merely exemplary.

The terms and words used in the following description are not limited to the bibliographical meanings and the same are used to enable a clear and consistent understanding of the invention. Accordingly, the terms/phrases are to be read in the context of the disclosure and not in isolation. Additionally, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

In an embodiment of the present invention is disclosed an automotive glazing (100) having a switching assembly. In a preferred embodiment, said glazing is sunroof of the vehicle. The sunroof may include a laminated glass panel containing the switching assembly, sandwiched between two substrates. The glazing unit may be or may not be curved. The schematic diagram of the automotive glazing (100) according to an embodiment of the present invention is shown in FIG. 2. It includes a switchable assembly (103) sandwiched between at least two substrates (101a, 101b) and an interlayer (102b). The automotive glazing unit (100) comprises a first substrate and a second substrate of glass or polymer. Said substrates comprises at least two surfacesan inner face and an outer face. Further included in the glazing is one or more interlayers and a switchable assembly (103) disposed between said first and second substrates, as seen from the figure. The voltage to the switchable assembly (103) is determined by the temperature of the glazing and life of the switchable assembly. The switchable assembly (103) is operably configured to a control unit (104). This control unit (104) is further configured to minimize the variation between an actual haze value and a desired haze value of the switchable assembly (103). The deviation of the actual haze value from the desired haze value is corrected by a correction component. The correction component is a function of temperature and/or it is a function of the age of the switchable assembly (103). The correction component compensates for the switching time increase. The switching time increase usually is experienced due to the age of the switchable film. The age of the switchable assembly may be defined by the service hours of said assembly or in other words, the number of hours said assembly has been functioning.

The switching assembly (103) may comprise one or more elements having switchable optical properties. It may include the electrically switchable film being disposed in between first and a second electrodes or terminals or bus bars as seen in FIG. 1. The electrodes or terminals or bus bars are generally arranged parallel to the surface of the substrates of the glazing. Said terminal may be electrically connected to voltage source. The electrically switchable film may be an electrochromic layer. The transmittance of visible light depends on the orientation of particles in the switchable film. Generally, when a voltage is applied to it the glazing turns transparent with nearly zero haze value. In the absence of voltage, the glazing may be opaque. In an exemplary implementation of the present invention, the switching assembly includes polymer-dispersed liquid crystals (PDLC) unit having terminals, one or more polyethylene terephthalate (PET) films, and one or more Indium tin oxide (ITO) films. PDLC unit may include polymer dispersed liquid crystal film or matrix.

Reference is made to FIG. 3a of the present invention that depicts an architecture of the control unit according to an implementation. Said control unit may be a dedicated control unit for the switching assembly or alternatively an electronic control unit (ECU) of the vehicle. The ECU of the vehicle include one or more modules capable of handling one or more dedicated functions. The modules include a power module, an isolator module configured for isolation or the electrical separation between the input and output of a DC-DC converter, local interconnect network (LIN) circuitry, a microcontroller and an output module that includes at least bridge circuit and low-pass filter (LPF). The control unit or the control system of the switching assembly would be a closed loop control system capable of monitoring the output current and with relevant current sensing hardware, it is regarded to accommodate the variation in actual current consequently adjusting the transmittance and/or haze. There is a dedicated control unit operably coupled with the PDLC film.

FIG. 3 a shows the block diagram of how an open loop based circuitry of the control unit (104) in the prior art solution would be like, while FIG. 3b shows the detailed block diagram of the closed loop based circuitry of the control unit (104) of the present invention. In the closed loop control circuitry, the current to the switchable assembly (103) is measured by current sensing signal conditioning, which is fed to the MCU and power consumed is estimated by the MCU. Depending on the estimated power, the voltage to be applied to the switching assembly is decided. In an implementation of the present invention, power is drawn from the vehicle battery. The circuit may have filter elements, LIN transceiver, boost converter, a core or the logic (such as a micro-control unit), and an amplifier. The MCU may be fed with switch inputs required for the switchable assembly (103) to function. The control circuitry includes modules for digital isolation and isolated power supply. The isolations facilitate for avoiding noise, and smooth generation of PWM signals. Reference is made to FIG. 3c that depicts a schematic diagram of a proportional and integral controller (PI) according to an exemplary embodiment of the present invention and FIG. 3d shows the block diagram of the same. The controller is based on closed loop function. The P.I controller includes a feedback control loop configured to determine an error signal by taking the difference between the output of the system and a predefined set point. The output from the system for the present case is power drawn from a source (for instance and not limited to a vehicle battery). The voltage point set for the functioning of the system is ideal for its functioning near the maximum power without causing the limiter to engage. The control mechanism of said controller involves a transfer function and thereby capable of finding the right proportional and integral constant parameter of the controller. However, this may not be the only means of finding the control parameters, there may be other means as well, as established in the art. In an exemplary embodiment of the present invention, the controller is configured to receive a current and/or voltage measurement from the output of the system. The controller is configured to obtain the power drained from the source (such as a battery) from the measured power. Once the power is obtained, the error signal is determined by obtaining the difference between the obtained power and the respective set point. The error signal is consequently fed into the P.I controller where it gets multiplied by the proportional (Kp) and integral constant (Ki). The output of the P.I control is a power value and in order to convert it to a quantity that is comparable to that of the control signal, it goes through a power to Pulse Width Modulation (PWM) signal converter, given by u(t) = Kp*e(t) + Ki Je(t) dt, where, Kp is the proportional gain constant, Ki is the integral gain constant, and e(t) is the error or the correction component.

The output from the PWM converter includes the adjusted PWM signal which is compared with the input signal to be applied to the switching assembly. For determining the deviation from the actual power and the desired power, a reference table is looked up. The reference table may contain data such as power, respective dimming function command, temperature and the like. Based on the reference, the power which may be drawn from battery is determined, and using the error signal it is accordingly corrected. The controller is further configured to check whether the power drawn is within a maximum limit permitted for the system. The adjusted PWM signal (output of PWM converter) then gets compared with the input signal (Amplitude to be applied), which is also a PWM signal, is thus fed to the controlled system. The P. I controller is configured to indirectly control the power utilized by the switching assembly by directly modifying the control signal. The correction component may thus be the error signal. When the voltage is supplied to the switching circuit, it is desirable to have a zero haze value, implying that transparency is obtained in the glazing.

Reference is made to FIG. 4 that shows a graphical presentation that the power consumed by the system is varied by the temperature on the glass or the substrates or the glazing. As seen from the indicative test data, an exponential pattern is observed in the power consumption with the temperature. In hot climatic conditions, the surface temperature of the glass substrates of the glazing changes based on both the inside temperature of the vehicle and its outside temperature. This will consequently impact the orientation of the liquid crystals of the switching assembly. In the extreme cold climatic conditions, the switching ON/OFF time i. e. the response time of the switchable assembly (103) to selectively turn transparent and opaque varies. The correction component determined by the controller compensates for the increase in switching time of the switching assembly, since the power drawn from source is corrected based on the feedback from output of the system.

In an implementation of the present invention, a DC high voltage is required for the switching assembly or the PDLC unit to operate at nominal AC voltage of 45 to 50 volts rms. The power module in the control unit may include a boost converter which converts a low voltage system (~12-volts) to high voltage system (~75 volts) including load dump and reverse voltage protections. The High voltage is configured to be fed as an input bus voltage to bridge circuits which works as output stage connected to PDLC unit load. A block diagram of the functioning of the power module is depicted in FIG. 5a.

The isolator module is based on galvanic isolation and may include couplers or drivers or both. FIG. 5b shows a simple block diagram of the isolation function. It is a design technique for electrical circuitry that separates electrical circuits to eliminate stray currents. The signals may pass between galvanically isolated circuits, but stray currents are blocked. Stray current as defined here may include electrical currents whose path is not their natural or optimal route, such as differences in ground potential or currents induced by AC power. Isolation functionality include the power category and signal category. Known in the art are several means for achieving isolation and depending on the design requirements a suitable means may be chosen. An example of signal isolation is considered in FIG. 5b wherein circuit 1 is the input signal circuits which may be derived from a high voltage section (indicated as circuit-2). The one side of the LIN section is connected to Circuit -1 , and the other side is to a regulator output derived from high voltage section (Circuit-2). The LIN circuitry takes a load distribution factor (LDF), in which the LIN cluster is defined and the LDF is the cluster specification. The nodes are realized as per specification and LIN circuitry is capable of converting LDF files to LIN application program interface (APIs). A schematic diagram of the workflow is shown in the diagram.

In an exemplary embodiment of the present invention is disclosed power correction determination that includes obtaining a channel output phase current and obtaining the channel output phase voltage. A control unit is configured to generate and control the input to the PDLC unit that includes varying amplitude and with constant frequency. The output from the system may indicate any of the following: an ideal condition, an output due to temperature of glazing or an output due to the age of the PDLC unit. FIG. 6 depicts these outputs in waveforms which are considered at 60HZ frequency with sinusoidal profile as per an exemplary implementation. Here, the sinusoidal profile is chosen in order to consider low EMI/EMC influences.

The performance of the PDLC unit embedded glazing is subjected to variation due to environment conditions such as power dissipation at component level, PDLC glass side (materials properties, variations on electro chemical properties which also have impact on the UV radiations and so on). KI is the co-efficient for PDLC film or unit and K2 is the coefficient of optical properties (say hot and cold conditions). In an implementation of the present invention, the controller module is capable of calculating the error, if there is a deviation from the ideal scenario and then the output will be based on the gain co-efficient and error as per PI controller logics. The gain co-efficient may be chosen even in bench setup conditions. Once the amplitude of the waveform is controlled, the output voltage waveform of current and voltage will indicate the amplitude change based on the PI controller functionalities.

Prom the existent solution of the switchable assembly (such as a PDLC unit) in automotive glazing, it has been observed that there is a deviation from the expected functioning of the unit, when the temperature of the glazing changes. A deviation from the expected functioning is also observed as the age or service hours of the switchable assembly increases. The solution rendered by the present invention factors in this deviation and applies a correction component to the voltage applied to switchable assembly to compensate for such a deviation. Accordingly, the present invention ensures in providing a switchable assembly showing stable performance as opposed to the deviated performance shown by the existent solution. In an implementation of the present invention, the controller or the electronic control unit is configured with the switchable assembly of the glazing to ensure the monitoring for the deviation in performance by applying a check on the power consumed by the system. The controller or the electronic control unit is configured to include a reference table containing the expected power consumption data for a certain temperature or for a certain age of the switchable assembly. When the power consumed by the system is obtained from the feedback of the closed loop, the reference table is referred and the deviation is identified. Further, the correction component is applied to the voltage and compensate for the deviation, thereby ensuring stable performance of the switchable assembly by compensating for the deviation due to temperature and age.

In an embodiment of the present invention is disclosed a method of minimizing the variance between the actual haze value and desired haze value of a switching assembly integrated in an automotive glazing by applying a corrected voltage to the switching assembly. Said switching assembly may include PDLC unit operably coupled to a respective control unit. As established above, it may be noted that the power drawn from the source by said integrated PDLC unit to function may follow an ideal condition. However, it has been observed that due to temperature of the glazing and the aging factor of the PDLC unit, there may be a deviation in the power drawn. The control unit is configured to continuously check whether such a deviation exists in a given system. The control unit of the switching assembly is a closed loop based control unit configured to supply the correct voltage to the switching assembly by determining a correction component for correcting the voltage supplied to the switching assembly. This is required when the control unit determines that the power drawn from the battery is beyond a permissible range offered by a PDLC assembly. The permissible range, inclusive of the maximum value of power is pre-set or predefined in the control unit. The correction component is a function of temperature of the glazing and/or a function of life of the switchable assembly. The correction component is obtained by the control unit by at least obtaining current as feedback from output and estimating power to the switching assembly by measuring the output current. The power values are determined based on pre-defined references, in which said pre-defined references contain values based on functionalities of the switching assembly. The control unit is configured to check if the estimated power is within an operational range or the permissible range. If the estimated power is within the range, no correction component is required. If the estimated power is beyond the range, then, there is a need to correct the voltage supplied to the PDLC unit so that the variance between the actual haze value and desired haze value of the switching assembly integrated in the automotive glazing is rectified. The control unit is configured to obtain the resistance and/or capacitance changes based on a durability test and obtained a correction component for correcting the voltage applied to the switching assembly.

FIG. 7 provides a sample data set that shows the effect of light transmittance (TL) and haze measurements with respect to temperatures. As is evidenced from the graphical representation, there are variations on said parameters when there is a variance in temperature and consequently, the current drawn will be more. In an embodiment of the present invention, the output power consumption (even in each individual channel current) is precisely monitored and controlled by applying the required amplitude voltage (which is inclusive of the correction parameter), so that in any case of variations due to the temperature changes, or the aging of PDLC film, the power consumption of the system never goes beyond the required reference or optimum current. FIG. 7 represents the total power consumption for 9-Channels Vs Temperature as per an implementation of the present invention. The graph indicates that the region of power consumption is not stable or in other terms not flat for full ON condition i.e maximum amplitude. Here, the total output power consumption includes real power (active power) and reactive power.

Experimental Results:

In the following is provided the experimental data showcasing the proof of concept of the instant invention: Reference is made to the FIG. 8a that depicts the data from laboratory experiments showcasing the degradation of the performance of PDLC. It has been observed that the performance of the PDLC gets degraded over time and the maximum transparency that the PDLC unit in glazing can offer for a constant voltage supply reduces over time. As disclosed in an embodiment of the present invention, to overcome such issues associated with PDLC unit and further to maintain the stable performance of the unit over a time, additional voltage may be supplied to the PDLC unit compensating for the degradation observed in such units. Similarly, depicted in FIG. 8b is a demonstration of increased switching time duration as the PDLC unit ages. This issue can also be controlled by additional voltage. The control unit takes into account the age of the PDLC and the number of switching cycles the PDLC film goes through and the deterioration in the switching time of PDLC for the level of aging of the PDLC. Based on this increased switching time, the control unit estimates the additional voltage to be supplied to the PDLC unit in order to maintain the same switching time. Reference is made to FIG. 8c that depicts a scenario where optical contrast ratio decreases with temperature. The contrast ratio is defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. This change in performance is due to temperature variation. This issue may be taken care by control unit by applying variable voltage based on the temperature of the glass unit. This in turn would help in reducing the power usage for PDLC control. Thus, the performance of the PDLC unit degrades with variation in temperature and its age. Overcoming both these issues associated with the PDLC unit, the present invention provides a solution by estimating the required voltage to be supplied to mitigate the malfunctioning due to age and temperature (here, it has been calculated indirectly). The inventors of the instant invention have conducted experiments to showcase increase in voltage resulting in faster switching time and better transparency. The results have been respectively tabulated herein below and have been depicted in FIG. 8d shows how increase in voltage can result faster switching time.

Table 1

Table 2 The various embodiments of the present invention, provides an automotive glazing unit (100). Said glazing unit (100) comprises a first substrate (101a) of glass or polymer having at least two surfaces, a second substrate (101b) of glass or polymer having at least two surfaces, and one or more interlayers (102) and an electrically switchable assembly (103) disposed between said first and second substrates (101a, 101b). The switchable assembly (103) is operably configured to a control unit (104) and the voltage to the switchable assembly is determined by the temperature of the glazing and life of the switchable assembly for ensuring stable performance of the switchable assembly. The control unit (104) is further configured to minimize the variation between an actual haze value and a desired haze value of the switchable assembly (103). The deviation of the actual haze value from the desired haze value is corrected by a correction component, wherein the correction component compensates for the increase in switching time of the switchable assembly (103). Said switching assembly (103) includes polymer-dispersed liquid crystals (PDLC) unit having terminals, one or more polyethylene terephthalate (PET) films, and one or more Indium tin oxide (ITO) films. The correction component is obtained as a function of the temperature of the glazing and/or a function of life of the switchable assembly. The control unit (104) includes a closed loop proportional and integral controller configured to obtain current feedback from the output of the control unit and determine the correction component based on the received feedback. The proportional and integral controller is configured to indirectly control the power utilized by the switching assembly by directly modifying the control signal. The proportional and integral controller is configured to indirectly control the power utilized by the switching assembly (103) by directly modifying the control signal. The control unit (104) is configured to determine the correction component by estimating the temperature parameter and the power from the measured output current, wherein the power supplied is within the desired optimal range and is configured to determine the correction component by obtaining the resistance and/or capacitance changes based on a durability test. The final voltage supplied to the switching assembly is the corrected output voltage by the corrected component. The automotive glazing unit (100) is sunroof of a vehicle. The control unit (104) is configured for isolated power supply and digital isolation for reducing noise and smooth signal generation.

The present invention further includes a method of minimizing the variation between the actual haze value and desired haze value of a switching assembly integrated in an automotive glazing by applying a corrected voltage to the switching assembly. Said switching assembly is operably coupled to a closed loop-based control unit configured to supply the corrected voltage to the switching assembly by determining a correction component, wherein said correction component is a function of temperature of the glazing and/or a function of life of the switchable assembly. The correction component is obtained by the control unit by at least obtaining current as feedback from output, estimating power to the switching assembly by measuring the output current. The power values are determined based on pre-defined references, and said pre-defined references contain values based on functionalities of the switching assembly. The method further includes checking whether the estimated power is within an operational range. If the estimated power is beyond the range, then, the method includes obtaining the resistance and/or capacitance changes based on a durability test and obtaining a correction component for correcting the voltage applied to the switching assembly.

Some advantages of the present invention are enlisted in the following:

• The present invention offers a stable solution for PDLC integrated in automotive glazing.

• The present invention offers closed loop implementation solution for accurate transmittance performance.

• The present invention improves the life of a PDLC integrated glazing. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments. List of reference numerals appearing in the accompanying drawings and the corresponding features:

100: The glazing with controller

101a, 101b: glass 102, 102a: interlayer

103: switchable assembly

104: control unit