TECHNICAL FIELD

The present disclosure relates generally to a system for determining defects, and particularly to a system that uses multiple response imaging in glazing manufacturing line to determine the defects associated with soldering process. The disclosure also provides a method for monitoring solder quality for 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.

Automotive glazing or vehicle glazing may include windshield, sidelite, quaterlite, backlite and the like. It may be laminated glazing or tempered glazing. An automotive glazing manufacturing line has many sub-processes which could be improved by utilization of an imaging system. In an automotive glazing manufacturing line, there may be a particular station where the glazing having connectors could be soldered by way of the soldering processes known in the art. Soldering may be done on laminated glazing or tempered glazing. During such process, defects may occur in the process, thereby rendering a defect in the glazing itself. The defects occurring due to manual or automated process need to be captured and respective measures need to be undertaken.

Reference is made to US2019084070A1 that relates to a MIG welding system including operating a vision module and a welding device, capturing a thermal image of a welding part using an IR thermal camera connected to the vision module, converting the image into a video signal, and transmitting the video image to the vision module, detecting whether there is slag through the vision module, determining whether the detected slag is fixed when the slag is detected through the vision module and analyzing the position of the slag and calculating a coordinate value when it is determined that the detected slag is fixed.

Again, reference is made to CN108562614A that discloses a chip pin welding defect detection system and method based on thermal imaging detection. The system comprises of a thermal imager, attested chip and a processing module, the thermal imager is used for detecting the temperature difference between a pin welding point of the tested chip and a background and recording the temperature field distribution of the surface of the welding spot, so that an infrared thermal image video of the pin welding point of the tested chip is obtained. The processing module is used for processing an infrared thermal image video to obtain a welding defect result of a pin of the tested chip.

Further, reference is made to patent literature EP2714602 (Al) and FR2975687A1 that describe a system to read information on the defects present in flat glass. This involves comparing the defective area to an area with a predetermined area with no defects to determine the presence of any defects on glass and a cutting system to remove the defective section from the flat glass panel by generation the optimum cutting plane for the glass.

A further reference is made to patent literature WO2015121548 (Al), WO2015121549 (Al) and W02015121550 (Al) that describe a system to read barcodes etched into the glass panel such that the barcode can be read through the main face of the panel and also through the thickness of the panel. For this to happen there is a back light required for illuminating the barcode so that it can be captured through the imaging system and be read by the system. In the above-mentioned prior art, there are several disadvantages and limitations such as the suggested solutions are offline process for soldering monitoring, the process control involved in the solution include manual intervention and solder defect identification is done post soldering process. Hence, there is a need for refined prediction model and monitoring method by image AOI (area of interest). It is, therefore, desirable and advantageous to provide an imaging system for reducing the defects during soldering process, and a method to monitor the soldering process in realtime.

SUMMARY OF THE DISCLOSURE

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.

An object of the present invention is to overcome the drawbacks of the prior art solutions.

Another object of the present invention is to provide a solution for the real-time monitoring of the soldering process on a glazing in an automotive manufacturing line.

Yet another object of the present invention is to perform multi-criteria optimization on the soldering process on a glazing in an automotive manufacturing line. Still another object of the present invention is to provide a method of through glass monitoring of temperature at the soldering joint on a glazing in an automotive manufacturing line.

A further object of the present invention is to provide a method to monitor the soldering process in real-time for identifying the defects during soldering process using the corresponding temperatures based on stress as an indicator.

Another object of the present invention is to provide a solution to identify the batches and match to system parameters in order to improve and thereby control the soldering parameters to provide alerts and improve glass traceability.

In an aspect of the present invention is disclosed an apparatus for determining defects in a glazing. The apparatus comprises plurality of sensors configured to obtain at least temperature, images of one or more connecting regions on the glazing during a soldering process on the glazing. It further includes a data acquisition system operably configured with the plurality of sensors for obtaining data from said sensors, a control unit comprising a processing unit operably configured with the data acquisition system for analysing the occurrence of a defect during the soldering process based on an analytical module and an alert unit operably configured with the control unit for providing alerts on detecting the occurrence of a defect. The control unit is configured for defect identification through inspection of a surface of a soldering region or connections therefrom on the glazing prior to or during the soldering process. The analysis for defect identification is based on the solder material in contact with a surface of a substrate of the glazing and the solder material in contact with a connector undergoing the soldering process and the sensor fusion data acquired from the plurality of sensors for optimal detection of defect in glazing. In another aspect of the present invention is disclosed a method of detection of defects in a glazing during a soldering process. The method comprises obtaining, by an imaging unit, images of the surface of the substrate for glazing from one or more sensing devices including a high definition (HD) camera and a thermal camera and further preparing, by a control unit, the obtained images for analysis of occurrence of defects by generation of temperature against time array data. The control unit will further obtain a threshold value for analysis with a maximum value, minimum value, ambient temperature and identifying the peak temperature values based on the inputs from the boundary conditions and will compare the temperature obtained from the sensing unit with the calculated threshold value. The method further includes the data acquisition system beginning to log the data and further analysis of occurrence of defect, if the temperature obtained from the sensing unit is greater than the threshold. The control unit would further compare the temperature of surface of the substrate of the glazing with a reference and trigger a signal for regulating or stopping the soldering process on the glazing, if obtained temperature is greater than a margin of error.

The various aspects of the present invention are directed at solution relating to inline defect detection during a soldering process of contacts on an automotive glazing (such as for instance, soldering of contacts of backlite panels) and correlating the data obtained from the theoretical stress calculation to determine if there is any stress generated to localized heating of the surfaces on the glazing, such as that of backlite panel in the examples, which leads to breakage of the backlite. The drawbacks mentioned in the background are overcome by an optimized imaging system which helps in detecting the glass model to determine the soldering parameters.

The imaging system and a method of through the glass monitoring (across thickness) of the temperature at the soldering joint is simple and effective solution that needs arrangement to align the camera system in a less intrusive arrangement. The solution is capable to monitor the soldering process in real-time. It includes the real time comparison of temperature and thermal stress between actual and computational data thereby performing multi-criteria optimization. The solution is further capable of reducing the defects during soldering process using forecasting methods and develop an optimized soldering process parameters. Additionally, it is capable of identifying the batches and match to system parameters in order to improve and thereby control the soldering parameters to provide alerts, which will enhance glass traceability.

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.

FIGs. 1 (a) - (c) illustrate block diagrams of the solution for determining defects in a vehicle glazing according to an embodiment of the present invention.

FIGs. 2 (a) - (b) illustrate exemplary embodiments of the solution for determining defects in a vehicle glazing according to the present invention.

FIG. 3 (a) illustrates two faces of a glass sheet as known in the art. FIG. 3 (b) illustrates the different layers of the solder material, the connector and the glass according to an example of the present invention.

FIG. 3 (c) illustrates the elongations of the glass and the solder material according to an example of the present invention.

FIG. 4 (a) illustrates a block diagram for the traceability of the vehicle glazing according to an embodiment of the present invention.

FIG. 4 (b) illustrates the method of detection of defects in a glazing during a soldering process according to an embodiment of the present invention.

FIGs. 5 (a) - (e) illustrate the experimental details of a scenario of defect detection according to an embodiment of the present invention.

FIGs. 6 (a) - (c) illustrate the experimental details of a scenario of no defect detection 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.

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.

The present disclosure describes a monitoring or an imaging system which helps in detecting the abnormalities in the soldering associated parameters in a vehicle glazing during soldering process in a vehicle glazing manufacturing line. The disclosure also provides a method of through the glass monitoring (across thickness) of the temperature at the soldering joint. In the instant disclosure a particular station where the vehicle glazing with connectors (are soldered) are considered. The fault occurring during the soldering and the defects thereof in the vehicle glazing occurring due to the manual or automated process are easily captured and updated to the disclosed system to alert operators or take corrective actions. The present disclosure makes use sensor fusion such as and not limited to that of an infrared (IR) camera, temperature sensors to monitor and control the soldering of contacts on the vehicle glazing. The soldering process indicated herein includes soldering associated with any kind of surface (such as and not limited to glass, black ceramic painted region i.e. BCP or single or double vehicle glazing) and also includes integration method involving heating and bonding like soldering (resistance, hot air, solder gun etc.), brazing, friction stir welding. In an embodiment of the present invention is disclosed an apparatus (100) for determining defects in a vehicle glazing as depicted in FIG. 1 (a). The disclosed apparatus comprises plurality of sensors (101) configured to obtain at least temperature and stress on the vehicle glazing during a soldering process and a data acquisition system (102) operably configured with the plurality of sensors for obtaining data from the plurality of sensors. The apparatus further comprises a control unit (103) operably configured with the data acquisition system for analyzing the occurrence of a defect based on analytical module or computational module. The apparatus also has an alert unit (104) operably configured with the control unit for providing alerts on detecting the occurrence of a defect. The control unit may include a processing unit. It may be capable of creating multiple data trails including tolerance of temperature differences, temperature distribution in the soldering area, soldering duration. The plurality of sensors (101) are configured to obtain parameters to examine the surface of the vehicle glazing, said parameters being at least temperature and images of one or more connecting regions and stress on the vehicle glazing during a soldering process on the vehicle glazing. Other parameters may include and not limited to power drawn by the soldering tool during the process.

In an embodiment of the present invention is disclosed an apparatus for determining defects in a vehicle glazing according to an embodiment of the present invention having actuators as alert unit. The plurality of sensors (101) in the apparatus at least includes an imaging unit. Said imaging unit includes a high definition (HD) camera and a thermal camera configured for image acquisition and analysis of soldering process, and said imaging unit is placed such that a field of view of the unit is in line with the soldering process being performed on the vehicle glazing. The thermal camera is configured to have the HD camera imaging output as an input parameter for correlating with the thermal camera for identifying defects during soldering. Said thermal camera is optimally positioned to obtain the maximum temperature and the average temperature of the soldering process. The defect detection may be achieved by way of image fusion segment for identifying the cause and location of the defects.

Reference is again made to FIG. 1 (b) that may depict exemplary embodiment of a system for regulating the soldering process in a vehicle glazing according to an embodiment of the present invention. The system comprises a sensing unit (201) comprising plurality of sensors configured to obtain at least temperature and stress on the vehicle glazing during soldering process and a data acquisition sub-system (202) operably configured with the sensing unit for obtaining data from the sensing unit (201). The system further includes a control unit (203). The control unit (203) comprises a processing unit operably configured with the data acquisition system for analyzing the occurrence of a defect based on analytical module. The system further includes an actuating unit (204) operably configured with the control unit for regulating the soldering process based on stress caused due to solder on the surface of the substrate of the vehicle glazing obtained by the analytical module. The system includes the same computational model or analytical module as that involving an equation which has been further established below as equation (1). The analytical or computational module for analysis of occurrence of defect in vehicle glazing during the soldering process may include computations considering both instantaneous data and historic data of stress and temperature of the surface of the substrate for vehicle glazing. The sensing unit (201) may mounted on a robotic arm or on a gantry system for easy access to a wider conveyor or for obtaining different angles with of view reduced number of sensors. The sensing unit (201) comprises at least an imaging unit (311) including a high definition (HD) camera and a thermal camera configured for image acquisition and analysis of soldering process. The actuating unit (204) is further configured for stopping the soldering process in the event of an abnormality in soldering process. The system may further comprise a power sensor configured for monitoring the power supply on one or more elements performing the soldering process. The disclosed system comprises sensor integration. The sensor integration determines the process parameters and quality control, QC, of heating grid.

In an implementation of the present invention, the imaging unit (311) is operationally configured with control unit (312) which in turn is operationally configured with actuators (313) as shown in FIG. 1 (c). The control unit (312) includes a processing unit (3122) that is configured to coordinate with a data acquisition system (3121) and actuator controls (3123). The actuators controls (3123) are capable of controlling the actuators (313). The actuator in an embodiment serves to divert the defective panels to an auxiliary line for further inspection. The actuators (313) referred in the figure may be and not limited to manual or automated ones. The type and nature of the actuator would depend on the nature of control to be exercised on the system. When the soldering process is manual, there may be indicators that may indicate the operator to stop the soldering if the temperature exceeds a certain range which may result in stress build-up. In case of an automated process, where the soldering system is mounted to an automation system (may be like system simple to just move the soldering system to and away from the glass or a robotic system) and depending upon the temperature and the predictive stress values from the model generated, a better control of the process may be achieved. In case where the process could not be controlled (applies to both the manual and automated systems) and the soldering temperature exceeds the limits then the glass is moved through a conveyor to a different zone for observation (like to check for crack formation/breakage). The actuators for this system may be the conveying system used for handling of the glass. It would be appreciated by one skilled in the art that the actuators may include one or more of such instances as mentioned here and a combination thereof although not limited to these. The imaging system in accordance with the present invention can be mounted onto a robotic arm or gantry system for easy access to wider conveyor or different angles with reduced sensors. The control unit (312) is configured to take data from the sensors and historical or reference data from storage for regulating the soldering process. The system may comprise visualization unit (315) for displaying alert or the data obtained from the sensors.

In an implementation of the present invention, the sensors are configured to communicate with data acquisition system using one or more communication methods and the data acquisition system may have dual connectivity with a storage or server as has been shown in FIG. 2 (a). These connections may be wired or wireless. The sensors may include but not limited to infrared (IR) camera, imaging devices, high definition (HD) imaging devices, ultrasonic sensor, and current sensor. The data acquisition system may comprise an analog to digital converter (ADC) which is connected with the current sensor, an interface for the camera or communications protocol (CSI/SPI) for connecting peripheral devices such as sensors and imaging devices to a central processing unit (CPU) which is connected to a transceiver module. The transceiver module can be wired or wireless such as and not limited to Wi-Fi, Bluetooth and the like.

The disclosed apparatus in accordance with said implementation of the present invention further comprises a storage server or an application programming interface (API) block. The storage server block may store data, perform analysis and transfer data from the sensors to the server or the visualization medium. The imaging unit further comprises an image acquisition and analysis of soldering process by using HD and IR cameras. The apparatus may include a power sensor configured for monitoring the power supply on one or more elements performing the soldering process. The arrangement is capable to align the camera system is in a less intrusive manner without hindering the process of soldering. The alert unit (104) may include visualization device configured to alert upon detecting the occurrence of any defects. For a manual system, this feature is capable of alerting the operator. The visualization devices may be a hand-held device to monitor various data points of the system as shown in FIG. 2 (a). The visualization devices may include and not limited to human machine interface (HMI) on control panels, portable devices, mobile phones, tablets, laptops and the like.

In an implementation is disclosed the process flow of analysis for the data from the thermal camera as has been illustrated in FIG. 2(b). The imaging system as disclosed herein acquires the input from the thermal imager for generating data such as temperature versus time array and thereby generating waveform to view the real time data. From the acquired temperature data, the threshold, the maximum value, the minimum value, the room temperature, and the like may be generated along the rising and falling edge detection of the values of the considered parameters. The temperature may be compared with threshold and if it is found to be greater than the threshold data logging is begun for analysis to create a temporary array to store the data points greater than the threshold. Furthermore, the soldering temperature data based on theoretical calculation (considering the glass mechanics) are referred. The obtained real time temperature is compared with the reference soldering temperature data and if it is greater than normal, then an appropriate action is taken such as triggering of an alarm to alert the soldering process or trigger the actuators to stop or regulate the soldering process. The system is capable of monitoring the soldering process considering the possibilities of errors in the system as well.

In an implementation of the invention, the thermal camera may be placed such that the field of view of the camera is in line with the soldering region on the vehicle glazing panel. When the soldering process begins, the thermal imager is configured to capture the data and compare the collected data with a pre-fed reference. If the thus obtained real time values are within a set limit of the reference the process is deemed to be fine. However, if there is a deviation of the obtained values from said set limit references, the vehicle glazing is isolated. The imaging features of the apparatus include said sensors along with the data acquisition system, storage/server and visualization tools that are capable of detecting the defects or abnormalities of the soldering parameters during soldering process. The imaging unit is capable of facilitating the apparatus to determine parameters such as stress through the glass for monitoring the soldering process based on the established boundary conditions that may include and not limited to reference data for a specific kind of glass, minimum temperature, maximum temperature etc.

The HD and IR images may be overlapped to obtain the required sensor outcome. The thermal camera is configured to use an HD imaging output as another input parameter to correlate with the thermal camera for identifying defects during soldering and it is placed such that the field of view of the camera is in line with the soldering are on the vehicle glazing panel. When the soldering processing starts the thermal imager captures the data and compares the collected data with a reference. The data captured from the one or more sensors may include temperature being obtained over an area, in-line the surface and through vehicle glazing. For instance, say if the soldering is being performed on face 1 of the glass, the sensors are configured to obtain the temperature in face 2. Reference is made to FIG. 3 (a) that shows an exemplary embodiment of the different faces of a glass in vehicle glazing to supplement the understanding of obtaining stress through the glass. Sensor fusion techniques may be used to replace one or more sensing devices. It may include other parameters such as and not limited to optical data, images from HD and IR camera, power drawn as well. The apparatus may use temperature probes, or power measurement sensor. The images from IR camera for temperature distribution in and around an area of soldering is obtained and overlaid with HD image to identify defects during the soldering process. If the real time values are within a set limit of the reference the process is deemed to be fine. If the real time values are showing deviation, then the glass is isolated. Reference is made to FIG. 3 (b) that discloses a layered diagram of the arrangement of the connector, a solder material and the glass below it. In an embodiment of the present invention, the control unit (103) is configured for defect identification through inspection of a surface of a soldering region or connections therefrom prior to soldering process. The defect identification is based on the solder material in contact with a surface of a substrate of the vehicle glazing and the solder material in contact with a connector undergoing the soldering process.

Reference is made to an implementation of the present invention, in which the imaging unit may be mounted at an optimal distance from the vehicle glazing panel focusing on the area under the soldering point. With this the apparatus is capable of obtaining the maximum, average temperatures on face 2 of the vehicle glazing during the soldering process on face 1. The so obtained profile of parameters is used to compare against a standard profile for any deviations. Said standard profile would be pre-determine and would be fed into the control unit. The glasses that shows a deviation from the standard values are then isolated for evaluation of stress.

In an implementation of the disclosed embodiment, the temperatures related to the stresses are the set boundaries for the soldering monitoring. The temperature on the materials involved during the soldering process are calculated computationally. The stress on the glass may be calculated as a function of time period after the soldering process. Critical stress points may be noted and the temperatures corresponding to the stresses are given as boundary conditions. Based on at least the boundary conditions and the material properties involved the stress distribution on the glass may be obtained. Boundary conditions may be set for the analytical purpose and may be defined for specific modules like individual model of glass and the individual area for soldering and the like. From the data observed from the temperature and stress developed, both average and standard deviations are computed for glasses which meet the parameters and are qualified for further steps. The glasses which exceed the temperature parameters for the process are isolated for observation since the stress builds up gradually over time and may even lead to breaking of the glass over a week or 10 days. Temperature range for the specified process and the boundary conditions for correlating with the simulation values are ascertained. In an embodiment of the present invention, the surface inspection of the vehicle glazing during the soldering process is given by stress on the surface of the substrate of the vehicle glazing is given by in which F is the force acting on the area A of the vehicle glazing, AT is the difference between the maximum temperature involved during the soldering process and room temperature, al is the thermal expansion coefficient of solder material, a2 is the thermal expansion coefficient of the surface in contact with solder material, El is the Young’s modulus of the solder material and E2 is the Young’s modulus of the surface in contact with solder material.

The calculations made herein could be split into 2 halves namely calculations involving solder material in contact with glass and calculations involving solder material in contact with connector. Materials when exposed to heat they expand or contract, is explained by the theory of expansion or contraction. When 2 blocks in contact with each other are exposed to heat they expand or contract with respect to each other, finding equilibrium expansion or contraction. The calculations are obtained using thermal expansion concept. Generally, at the time of soldering, a connector with solder material is placed on the glass surface of the vehicle glazing and heat is supplied to connector. Ordinarily, the temperature rises more than 300°C in the solder material. As a result, the solid solder material melts and further cools down to become solid again, thereby connecting the connector to the glass. The stresses on glass start to generate when the solder material starts to form solid again and reach temperatures 50°C and 25°C. It has been observed that stresses are generated at the start of solidus point of solder material, both materials elongate at different magnitude depending on the expansion coefficient of the individual materials. Solder having more expansion coefficient than glass tends to expand more than glass material. Reference is made to FIG. 3 (c) that represents the differential heating of said materials. AL1 shown therein depicts the elongation of solder material, AL2 shows elongation of glass, ALe shows the equilibrium elongation of both materials, Al represents the decrease in length because of the compressive forces acting on solder because of glass, A2 represents the increase in length because of the expansion forces acting on glass because of solder material, ag is the thermal coefficient of glass and as is the thermal coefficient of solder material. At the equilibrium the compressive force acting on solder material because of the glass resistivity to expand and tensile force acting upon the connecting surface of glass because of solder expansion are both equal. The computation module for analysis of occurrence of defect in vehicle glazing during the soldering process includes computation considering both instantaneous data and historic data of stress and temperature of the surface of the substrate for vehicle glazing.

In an embodiment of the present invention is disclosed the traceability of the glass if there is a deviation from normalcy during the soldering process on the vehicle glazing. FIG. 4 (a) illustrates a block diagram for the traceability of the same. The disclosed system in accordance with the present invention can support identifying the glass number, batch and model in the manufacturing line and keep a record of the same in a database. This data may be used in creating a historical information for further predictive and preventive actions for the process. The data acquisition system (102) may be configured to obtain and further record one or more parameters associated with the vehicle glazing for enabling the traceability of the vehicle glazing in case of a deviation from normalcy during the soldering process.

The sensor inputs and other inputs for traceability of glass may include thickness of glass, glass model, geometry identification of glass, soldering power, and thermal-mechanical stress model. An analysis engine of the control unit is capable of taking the glass properties that includes machine and stress response and co-ordinate with the storage or server for desired traceability of glass. In this embodiment of the present invention, the traceability of glass may be limited to rejected vehicle glazing only and may be recognized as a control feature of the system disclosed herein. In this embodiment, the glass may be diverted to an auxiliary line for further inspection via known glass panel transfer mechanisms. Further to which all such glass panels may be sequentially numbered before the soldering process so that the defective cases can be flagged in the database for easier process control.

In an embodiment of the present invention is disclosed a method of detection of defects in a vehicle glazing during a soldering process as has been depicted in FIG. 4 (b). The method may commence with obtaining (SI 01), by the imaging unit, images of the surface of the substrate for vehicle glazing from one or more sensing devices including a high definition (HD) camera and a thermal camera. Further to which, the method includes preparing (SI 02) the obtained images for analysis of occurrence of defects by generation of temperature against time array data. This preparation is performed by the control unit. A threshold value for analysis with a maximum value, minimum value, ambient temperature is then obtained (SI 03) by the control unit for identifying the peak temperature values based on the inputs from the boundary conditions. The control unit then compares (SI 04) the temperature obtained from the sensing unit with the calculated threshold value. The data acquisition system then logs (SI 05) the data and analysis of occurrence of defect in case if the temperature obtained from the sensing unit is greater than the threshold. The control unit compares (SI 06) the temperature of surface of the substrate of the vehicle glazing with a reference. The control unit now triggers (SI 07) a signal for regulating or stopping the soldering process on the vehicle glazing, if obtained temperature is greater than a margin of error. The apparatus in accordance with the present invention have been tested, to check for deviations from the normal conditions during the soldering process in a vehicle glazing. The camera has been mounted at a distance of 400-500 mm from the vehicle glazing panel focusing on the area under the soldering point. With this, the maximum, average temperatures on face 2 during the soldering process have been obtained. This profile is further used to compare against a standard profile for any deviations and such vehicle glazing will be quarantined for evaluation of stress. The sampling sensor data in accordance with the present invention provides sampling rate and sleep mode. The comparator compares the actual with the reference data. In accordance with the present invention the temperatures related to the stresses are the set boundaries for the soldering monitoring. The temperature on the materials involved during the soldering process have been calculated computationally in the computational data block.

To see a procedure if we can correlate the average temperatures shown by the IR camera to the temperature distribution values calculated computationally. During the soldering Process, the temperature on the outer surface have been captured. There may be 2 cases now to be determined: the power supplied is just enough to melt the temperature and the power supplied is high more than required (case of creating runaway of the solder material). The temperatures corresponding to the both scenarios have to be checked, and the material behavior of the solder material have to be checked to identify the type of defects that may occur under the foot of the bridge for higher power.

Once said factors have been determined, a model has been designed in a finite element analysis software to check for the stresses. If the stresses developed are in the allowable ranges, then the temperature corresponding to the model have been set as boundary conditions and it can be said that this is within acceptable limits. If the stresses are not in the boundary conditions, then the temperatures corresponding to the stresses are said to be not acceptable thereby indicating the possibilities of defects. The stress measurement on the vehicle glazing during the soldering process may utilize a polarized scope to get before and after soldering mechanical stress data.

Here, for stress calculation, the materials that are involved include glass, solder material (for example alloy of Tin, Silver and Copper), and connector (for instance, stainless steel). Some of the assumption and approaches made include the blocks being assumed to be composite blocks in contact with each other, black and silver layers being eliminated, which are part of automotive glass, time dependency have not been considered, thickness of the glass have not been considered as the focus is currently on the contact of the two materials, stresses are assumed to be caused due to cooling down and solidification of solder material, and the temperatures of the individual parts in the model are independent to each other (since they have their own cooling rates).

The temperatures on each of the material involved in the soldering process have been given as inputs to calculate stress which has been calculated computationally via finite element analysis. Further, the stress on the glass as a function of time period after the soldering process have been calculated computationally. The critical stress points have been noted and the temperatures corresponding to the stresses have been given as boundary conditions which is 140 Mpa of tensile stress and temperature condition is 150°C. Considering the disclosed computational model, the stress so defined in terms of co-efficient of thermal expansion and Young's modulus is provided at equation (1). In the following table is provided different tensile stresses calculated due to soldering on the vehicle glazing:

Table 1

The embodiments of the present invention may further include identifying the batches and matching to the system parameters to improve the effectiveness of the system and then control the soldering parameters providing alerts. The analytical data model in accordance with the present invention improves the model with the exact set points for soldering. This includes the pressure points, boundary conditions and soldering parameters as well. Multiple soldering simulations with different sets of positions of electrode on the connector which connects heating network to the battery may be obtained, to see the temperature distribution variation and stress generated. Further to this, the tolerance of temperature differences, performing multiple set of trails during soldering and computational as well may be defined.

Industrial Applicability

In an embodiment, the disclosed imaging system to determine the defects for automotive soldering includes a multi-response imaging system that may be used in heating grid, antenna line (automotive) soldering, gypsum dam curing, CFL line curing, glass pilot line.

Experimental details as available from a manufacturing line in a plant:

Reference is made to figure 5 (a) that represents data taken during a process of soldering on glass from a manufacturing plant. The thermal image of temperatures on face 1 of the glass in a vehicle glazing are obtained for lower and higher powers by the apparatus according to the present invention and further to which the apparatus is configured to capture the average temperature and the same is used for the validation using finite element analysis simulation, for correlation of stresses on face 2 with temperatures on face 1. As have been detailed herein above, the apparatus according to an embodiment of the present invention is capable of calculating the stress through the glass post attaining parameters such as temperature, in which the calculations are based on the analytical module involving equation 1.

Defect detection '. From the data so obtained, the control unit of the apparatus is configured to detect a defect based on the stress data, compared with boundary conditions which have been earlier derived. The possible causes of the defects during the soldering process may be due to positioning of the soldering equipment’s electrodes at the edges, however not limited to this and the parameters that are considered for the simulation by the control unit includes flow of electricity from one end to another, the contact of the heat source electrode and heating due to resistance, time of soldering (~ 3s) and the melting point of solder is at around 180°C. Reference is made to FIG. 5 (b) that shows the connector design with the soldering electrode positioned at the edges while FIG 5 (c) discloses the heat distribution on the solder material at the end of soldering process.

Some of the observations from the data obtained from the imaging unit as depicted in the referred figure may include a black region showing areas which is not melted, the heat distribution being uneven, a possibility that the solder material is not evenly spread which may cause additional stress build-up and it is further noted that lowest temperature on the solder material is 157°C. The reasons for defects in the process of soldering may be attributed to the wrong position of the soldering system that results in creating holes in solder because of excess heat at corners. FIG. 5 (d) shows the connector with hole locations which have been created due to wrong positioning of system. FIG. 5 (e) depicts the temperature on solder at the end of 3 s and the respective temperature distribution on face 1 of the glass and the corresponding stress developed on glass surface. The temperatures on the face 1 of vehicle glazing is below 50°C, which is a deviation from the normal conditions. The required alert indications were provided during the process and the vehicle glazing has been isolated for further observation.

No defect detected. A second scenario is now considered in which no defects were identified, the identification being made based on the stress data compared with boundary conditions derived. A case of soldering of symmetric antenna connectors are considered, in which the average temperatures on face 1 is 79°C and the maximum temperature of the solder material is maximum of 249°C which is more than 183 °C (melting point of Sn-Pb). No deviation from normalcy has been noticed herein. At the end of 12 Hours of cooling the maximum stress generated on the glass is 106 Mpa, which is still in limit (normally for glass the value is expected to be < 140Mpa). Reference is made to FIG. 6 (a) that shows an image of symmetric position of the soldering points on the connector. FIG. 6 (b) depicts the temperature on solder material and the respective temperature distribution on face 1 of the glass and the corresponding stress developed on glass surface. 100 Mpa is the compressive stress on the glass surface after tempering in addition to the glass max tensile strength. For utilizing a power symmetric design for the simulation it has been observed that with the increase of temperature by 10°C, the stresses get reduced by 22% and the maximum temperatures on face 1 is 93°C while the maximum temperature of soldering material is 308°C. FIG. 6 (c) shows the thus obtained temperature distribution on face 1 and solder material along with the stress developed on glass for a symmetric power simulation.

With the disclosed invention, stress measurement system is online and the same is performed by way of using a photo-elastic or optical birefringence method to determine stress variations during the process. The apparatus and system involves multi-criteria optimizations for the soldering process for instance and not limited to temperature data (instantaneous, gradient, time), current data, HD image data. Disclosed solution uses imaging data or sensing data as inputs for self-learning algorithms to improve predictability of the defective glass identification and/or for providing optimized control signals for processes based on the reference data. It is advantageously useful for defect identification through inspection of surface of the bus bar or soldering region prior to soldering process.

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

• The disclosed invention provides an online process for monitoring the soldering process on a vehicle glazing and the process of soldering could be controlled with minimum manual intervention and the soldering defects could be identified even after the soldering process.

• It provides a method to monitor the soldering process in real-time with real time comparison of temperature and thermal stress between actual and computational data thereby performing multi-criteria optimization.

• The disclosed invention facilitates for reducing the defects during soldering process using forecasting methods.

• The disclosed invention facilitates for identifying the batches of glass and matching to machine or system parameters to improve / control soldering parameters provide alerts and the like, thereby offering glass traceability.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed. Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Certain features, that are for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in a sub combination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

The description in combination with the figures is provided to assist in understanding the teachings disclosed herein, is provided to assist in describing the teachings, and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application. As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive- or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

List of reference numerals appearing in the accompanying drawings and the corresponding features:

101: sensors

102: data acquisition system

103, 203, 312: control unit

104: alert unit

105, 205, 315: storage/ server

201: sensing unit 201

202: data acquisition sub-system 202

204: actuating unit

311: imaging unit 311

3121: data acquisition system

3123: actuator controls

313: actuators

315: visualization

3122: processing unit

S101-S107: method steps