FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
DEVICE FOR CHECKING THE WORKING OF WINDSHIELD GLASS DEFOGGER AND METHOD THEREFOR
Applicant:
MAHINDRA & MAHINDRA LIMITED
GATEWAY BUILDING, APOLLO BUNDER,
MUMBAI-400001,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE USED

Field of the Invention
The present invention relates to a device for checking the working of windshield defogger, particularly rear windshield glass of a motor vehicle. The present invention also relates to a method for checking the working status of the windshield glass defogger.
Background of the Invention
Accumulation of moisture on windshield glasses of motor vehicles is termed as fogging. This fogging obstructs visibility all-around the vehicle and may often pose a major safety hazard for the occupants of the motor vehicles while driving, changing lanes or even turning left or right. Therefore, excessive fogging of windshield glasses of motor vehicles is not just a safety hazard, but a major consumer and traffic concern.
Most of the motor vehicle users are unaware of the methods for defogging moisture from windshield glasses, because different weather conditions require different approaches for defogging the windshield glasses of motor vehicles. In order to avoid such difficulties faced by the motor vehicle users, at present, high-end motor vehicles are normally equipped with an automated defogging feature, which not only maintains a comfortable interior, but also provides the best possible visibility around the motor vehicles for facilitating both the drivers and the occupants thereof. However, for this automated defogging feature, an excessively high cost is involved and there is a continuous endeavour by automobile manufacturers to look for ways to lower any cost of defogging operation in the motor vehicles manufactured by them.
At present, in high-end products like Scorpio Export, Genio Export and Rexton by Mahindra & Mahindra Limited, the defogger of the rear windshield glass needs to be checked at CAI (Customer Acceptance Inspection) point after shower testing of the vehicle.

Conventionally, the function of defogger is checked by a switch operated on the Crash pad and/or manually by an associate using his hands by touch and feel, and thus they come to a conclusion, whether more time is needed to heat the windshield glass to reach the required temperature. Often, this manual checking may require even two associates at the same time. This is particularly cumbersome in case of a rear windshield glass of the motor vehicle.
Prior Art
In a motor vehicle assembly-line configured for 22 JPH, the maximum cycle time permissible at any stage should be less than or equal to 2.72 minutes. In an exemplary existing arrangement, the checking time taken at shower checking stage of the motor vehicle is 2.51 minutes and the time taken during the subsequent defogger checking stage is 5.23 minutes. Here, defogger checking time is higher than the maximum permissible time for 22 JPH assembly-lines, thus posing major bottlenecks at CAI points, which leads to vehicle pile-ups in the assembly lines.
In order to study the above exemplary defogger inspection process in detail, the time taken for various defogging process steps was recorded, which is tabulated below:

Sr. No. Process Step Time (sec)
1 Defogger coil heating 240
1 Opening the door 2
2. Switching-on the Defogger 2
3. Checking one side (LH/RH) of Windshield glass 28
4. Moving to other side 6
5. Checking other side (RH/LH) of Windshield glass 28
6. Reconfirming the results 4
7. Switching-off the Defogger 2
8. Closing the door 2
Total Inspection Time (sec) → 314

Disadvantages with the prior art
There were several constraints noticed during the defogger checking method studied above. These constraints and their impact on the working of the defogging are briefly summarized below:
1. The conventional defogging method involves subjective inspection process, which is dependent on heating the defogger coils embedded in the rear windshield glass. This may render the defogger inspection process not entirely fool-proof. Due to this constraint, the operator performing the defogger inspection is not self-confidence about the results obtained subsequently.
2. It was recorded that the checking for the defogger functionality took about 5.23 minutes on an average, which poses major bottlenecks for the CAI process flow.
3. It was also noticed that the operator was subjected to a number of stretching and bending movements for checking the defogger working, thus ergonomically it falls in the category of Yellow Stage and it brings down the morale of the operator carrying out the defogger inspection process.
4. Finally, the conventional defogger inspection process also necessitated a separate working space in the assembly plant layout, which should be strictly dedicated to motor vehicles waiting for the defogger functionality inspection.
Objects of the Invention
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a device for checking proper working of the defogger for a rear windshield glass.
Another object of the present invention is to reduce the overall cost of manufacturing of motor vehicles fitted with defogger.
Yet another object of the present invention is to simplify the working of defogger, thereby facilitating an effortless operation thereof.
Still another object of the present invention is to provide a device for checking proper working of defogger, which is easy from the point of view of serviceability thereof.
A further object of the present invention is to provide a defogger which involves lower replacement costs.
Another object of the present invention is to reduce motor vehicle inspection time in the assembly line.
Yet another object of the present invention is to cater to motor vehicles, where the quality is a major issue, however the manufacturing process is adapted to arrive at a compromise between the sophistication and simplicity during defogger inspection.
Still further object of the present invention is to provide a device for defogger testing facility on vehicle TCF (Trim, Chassis and Final Assembly line).
Yet further object of the present invention is to avoid manual checking of the defogger for rear windshield glass by hands employing touch and feel method.
A still further object of the present invention is to provide a method for checking the working status of a defogger coil by using a defogger checking device according to this invention.

Description of the Invention
In order to investigate the design of the defogger for the windshield glass, further studies were conducted, which included the following approach:
• To exploit the current flow, current flow in the defogger coils was studied.
• To explore the feasibility of a simple test-lamp for checking the defogger function, the voltage drop during the current flow was recorded.
• To a mechanically simple and operator friendly device, the terminals and coil arrangement in the windshield glass of the motor vehicle was also studied.
In addition, to investigate the mechanical joints and rear space of the motor vehicle, still further studies were conducted, which are also enumerated below:
• To provide device access to each and every model and variant of the motor vehicle being produced, various available joints were studies in detail.
• To thrive for the suitable materials for the testing device, without incurring any additional costs, the scrap yard and rejection bins were also studied, to check the availability of different scrap materials in the manufacturing plant.
The above detailed studies led the inventors to designing a new defogger checking device.

One of the first steps in realizing this new device was to strive for developing the coils in the defogger, which could be expedited for the device having a speed of detection, which is at least equal to the speed of the electric current.
This way, the dependence of the defogger checking method on the speed of current flow through the defogger coils was eliminated.
In the second step, it was conceived to illuminate a test lamp by passing the electric current during conducting the defogger checking method.
In a third step, it was undertaken to simplify the cover design and the access for the defogger checking device. This included the following stages:
• Option 1: A straight cylindrical cover of 80 mm maximum length
was chosen after studying the rear space of all the variants of the
vehicle being produced.
This has the implication that the defogger checking device became rigid and was not found suitable for all vehicle variants.
• Option 2: An 'L' shaped cylindrical cover of a length AB = 69
cm and BC = 40cm was chosen.
This design demonstrated that the defogger checking device became cumbersome and was suitable for a specific vehicle variant only.
• Option 3: An 'L' shaped cylindrical cover of length AB = 69 cm
and BC = 40 cm with a hinge joint at the L-joint was designed for
imparting the device access to all models and variants of the motor
vehicle.

The above designing process and studies lead to the following unique solution of the defogger checking device:
i) (-) terminal was made from scrap materials.
ii) Cover was also made from scrap materials, e.g. scrap trolley stands.
iii) (+) terminal was made from wheel nuts.
iv) Testing-lamp was made from scrap roof-lamps.
Therefore, by overcoming the difficulties with the conventional defogger checking method, and adopting novel approach to developing the defogger checking device as discussed above, a defogger checking device has been developed in accordance with the present invention for checking the proper working of the rear windshield glass defogger, which is made exclusively from the in-house components.
In this device, one of the terminals is made as a positive terminal and connected to rear windshield glass defogger strip and the other terminal is made as a negative terminal and used for earthing via a door striker. A bulb is connected between these terminals.
On operating the defogger switch, a proper working of electrical supply to the defogger strip can be checked by using this device. The bulb of the device glows, when the defogger strip sufficiently heats the windshield glass. If the defogger strip does not heat the windshield glass sufficiently or if electrical supply not available at the defogger strip, then the bulb of the device does not glow.
A comparative study was conducted by using the defogger device in accordance with the present invention, the results of the time taken for various defogging process steps was recorded, which are tabulated below:

Sr. No. Process Step Time Taken (sec)

Conventional Method New Method
1 Defogger coil heating 240 0
2. Opening the door 2 2
3. Switching-on the Defogger 2 2
4. Checking one side (LH/RH) of Windshield glass 28 0
5. Taking Defogger from stand 0 3
6. Moving to other side 6 0
7. Checking the continuity of Defogger wiring 0 7
8. Checking other side (RH/LH) of Windshield glass 28 0
9. Keeping the Defogger at the stand 0 3
10. Reconfirming the results 4 0
11. Switching-off the Defogger 2 2
12. Closing the door 2 2
Total Inspection Time (sec) → 314 21
Therefore, the new approach by using the defogger checking device in accordance with the invention could produce excellent results at a very nominal cost. This new device brings down the defogger checking time from the earlier observed 340 seconds to mere 21 seconds, thereby completely eliminating the assembly-line bottleneck discussed above. This new device also dispenses with the requirement for using two operators for checking proper defogger working and also reduces the requirement of manpower by half.
Summary of the Invention
In accordance with the present invention, a device is provided for checking the working of a defogger coil in motor vehicles, wherein the device comprises an 'L' shaped configuration having a positive terminal and a negative terminal for checking the functioning of defogger coils in different variants and models of the motor vehicles.

Typically, the device comprises a short leg and a long leg; both the legs are connected to each other by means of a hinged joint.
Typically, the positive terminal is configured at the shorter leg end and the negative terminal is configured at the longer leg end thereof; both the legs adapted to be connected to each other by means of a hinged joint for checking the defogger functioning of different variants and models of the motor vehicles.
Typically, the longer leg includes an indicator bulb substantially in the middle portion thereof for testing the continuity of the electrical circuit of the defogger coil.
Typically, the negative terminal is made of scrap materials available in-house.
Typically, the positive terminal is made from wheel nuts available in-house.
Typically, the testing lamp fitted in the middle of the longer leg of the device is retrieved from the scrap available in-house.
Further, in accordance with the present invention, a method vehicle is disclosed for checking the defogger of a motor vehicle by using a defogger checking device, wherein the method comprises the following steps:
- dismounting from the motor vehicle;
ensuring that the Ignition switch is ON;
keeping the Defogger switch ON (confirming the defogger switch condition by keeping illumination light ON);
taking said defogger checking device from the stand thereof and moving to the rear side door of the motor vehicle;
opening the right side door of the motor vehicle and connecting the positive terminal of said defogger checking device to the positive

terminal near the right side connector of the windshield glass and the negative terminal of said defogger checking device to any coil on the windshield glass on the left side;
checking the glowing status of the bulb provided on said defogger checking device;
wherein a non-glowing bulb status indicates a defect in the electrical circuit of the defogger coil and a glowing bulb status indicates a properly functioning defogger coil of the motor vehicle.
Brief Description of the Accompanying Drawings
The present invention will be briefly described with reference to the accompanying drawings, wherein:
Figure 1 shows a motor vehicle with the time taken by shower checking stage and subsequent defogger working checking stage in a conventional arrangement;
Figure 2 shows a conventional arrangement during the operational movements of the operator/s around the windshield glass of motor vehicle for manually checking the defogger working;
Figure 3 shows a perspective view of a motor vehicle windshield glass embedded with defogger heating coils;
Figure 4 shows the schematic concept of electric current based test lamp for checking defogger working in accordance with the invention;
Figure 5 shows an 'L' shaped cylindrical cover of length AB and BC in accordance with the invention;

Figure 6 shows material savings obtained by making various components of the cylindrical cover in accordance with the present invention having a hinge joint and by using scrap materials available in-house; and
Figure 7 shows the reduced manpower requirement for checking the defogger working by employing a single operator from only one side of the vehicle.
Detailed Description of the Accompanying Drawings
The device for checking the working of windshield glass defogger in accordance with the present invention will now be described in more details with reference to the accompanying drawings, without limiting the scope and ambit of the present disclosure in any way.
Figure 1 shows a motor vehicle with the time taken by shower checking stage (Stage I) and subsequent defogger working checking stage (Stage II) in a conventional arrangement. It is clear from Figure 1 that Stage-I takes less time (2.51 min) than the time taken (5.23 min) for Stage-ll. Due to this time difference, there is a serious bottleneck in the CAI (Customer Acceptance Inspection) because of pile-ups of the motor vehicles in the assembly lines. For example, in case of an assembly line designed for 22 JPH (Jobs per hour), the maximum cycle time allowable at any stage should be less than or equal to 2.72 minutes. In the existing arrangements, this was observed to be much higher (2.51 min + 5.23 min = 7. 74 min) than the permissible cycle time for completing this process.
Figure 2 shows a conventional arrangement during the operational movements of the operator/s around the windshield glass of motor vehicle for manually checking the defogger working. Here, the operator is subjected to a number of stretching and bending movements for checking the defogger working, which is a Yellow Stage category economically and thus, this operation normally brings down the morale of the operator performing the

defogger inspection. This also required one operator each to be present on either side of the vehicle checking the defogger working.
Figure 3 shows a perspective view of a motor vehicle windshield glass 10 embedded with defogger heating coils 14 in accordance with the present invention. This was achieved by developing the coils in the windshield glass. These coils 14 could be expedited for the device having a speed of detection, which is at least equal to the speed of the electric current. The device includes an 'L' shaped checking tool made of waste or scrap materials. For example, the positive terminal is at the free end of the shorter leg marked on RHS and the negative terminal is at the free end of the longer leg marked on LHS. These two legs are connected to each other by means of a hinged joint. Further, the longer led has a testing bulb almost in the middle thereof, which glows if the defogger is working properly, otherwise the defogger is not functioning properly. In this way, the process of checking the defogger working, which was conventionally based on the speed of current flow through the defogger coils, was eliminated.
Figure 4 shows the schematic circuit of testing lamp which may glow by passing electric current and thus used for checking defogger working in accordance with the invention. The positive and negative terminals of a battery 20 were connected in series to a testing lamp 30 by means of wires 40. Further, the negative terminal was made from scrap materials and the positive terminal was made from wheel nuts. The testing lamp 30 was also used from in-house scrap.
Figure 5 shows an 'L' shaped cylindrical cover of length AB and BC in accordance with the invention. It was studied that there are three different variants possible while designing the cover. In the first cover design which may be common to all variants, a straight cylindrical cover of maximum length 80 cm (AC or F) was configured. However, the problem remained that it was rigid and does not actually suit all the variants of the motor vehicle. In a second cover design, a fixed 'L' shaped cylindrical cover of length AB=69 cm

and BC=40 cm. However, this was also found cumbersome and suitable for only a specific variant of the motor vehicle. The third cover has a unique design, which consists of an 'L' shaped cylindrical cover having length AB = 69 cm (distance D) and BC = 40 cm (distance E), however provided with a hinge joint at the L-joint giving optimum results. This design imparted the device access to all models and variants of the motor vehicle.
Figure 6 shows material savings obtained by making various components of the cylindrical cover in accordance with the present invention having a hinge joint (Figure 5, third design) and by using scrap materials available in-house. For example, on the left side in this figure, the yellow encircled portion 50 of the device is the negative terminal made of scrap materials. The covers 90 and 100 are made from the material of scrap trolley stands. The second green encircled portion represents the testing lamp 60 also retrieved from in-house scrap. Further, the 'L' shaped hinge joint 70 shown on the right in this figure is capable of providing access to all models and variants of the vehicle. The positive terminal 80, i.e. the second yellow encircled portion shown at the bottom of the figure, is made from wheel nuts available in-house. Exemplarily, the distance 110 between the negative terminal 50 and the hinge joint is 67 cm, while the distance 120 between the hinge joint 70 and the positive terminal 80 is 38 cm. The distance 130 between the hinge joint 70 and the testing lamp 60 is 37 cm.
Figure 7 shows the reduced manpower requirement for carrying out the checking of the defogger working by employing a single operator from one side of the vehicle.
As explained in Figure 1 and 2, earlier due to dependence of inspection method on the heating of coils and the windshield glass, the process of inspection included inspecting both the sides of the windshield glass on the basis of touch and feel. Therefore, for completing the defogger inspection process without causing any major bottleneck, two inspectors were required. However, with the development of the defogger checking device in

accordance with the present invention discussed above, the dependence on heating of coils got eliminated and the defogger inspection process needs only to check the current flow in the defogger coil. Hence, only one inspector is required for completing the defogger inspection process. In this way, the manpower requirement at the defogger checking stage was also reduced.
Working Principle of the invention
Referring to the figures, the step-by-step method of defogger checking using this device comprises of the following steps:
Dismounting from the vehicle.
Ensuring the Ignition switch is ON, also keep the Defogger switch ON (confirm the defogger switch condition by keeping the illumination light ON).
Taking the defogger checking device from the stand and moving to the rear side door.
Opening the right side door of the motor vehicle and connecting the positive terminal of the defogger checking device to the positive terminal near the right side connector of the windshield glass and the negative terminal of the defogger checking device to any coil on the windshield glass on the left side.
Checking whether the bulb on the defogger checking device is glowing or not, if the bulb is not glowing then there is problem with the electrical circuit of the defogger coil and we should check further for electrical circuit, windshield glass or other defects in the defogger coil.
If the bulb on the defogger checking device is glowing, then the defogger coil is working correctly.

Technical Advantages & Economic Significance
Some of the technical advantages of the device proposed in accordance with the present invention are as under:
1. Application of basic physical principle of applying an electric current in the defogger coils has eliminated the earlier dependence of inspection method on the heating of the coils, which took 5.23 min. per motor vehicle.
2. Time required for the conventional inspection process = 314 sec
Time required for the inspection process in accordance with the present
Invention = 21 sec
Time Saved due to Invention = 293 sec (4.88 min)
Capacity improvement of CAI testing line =100%.
3. Defogger Checking Device has eliminated the dependence of
inspection process on the manual touch and feel by the operator and
therefore, the inspection process makes him more confident, getting
completed with the speed of electric current, thus improving the
productivity of the entire process.
Capacity of conventional CAI testing line = 11 vehicles/hour (11 JPH),
Capacity of new CAI testing line with the defogger checking device in
accordance with the invention = 22 vehicles/hour (22 JPH).
4. Defogger device is configured with a mechanical hinge joint to give it
access to all the models and variants of motor vehicles, so that it can
be used on any platform (Multi Model platform of the motor vehicle).

Some of the economic advantages are as given below:
1. Investment cost for the material of the defogger checking device is almost Zero as the device has been manufactured from scrap materials available in-house.
2. Only one operator is required for defogger checking operation with the productivity improvement in accordance with the invention, hence saving substantial manpower cost/year.
Manpower Cost saved per Year = (2-1)*20000*12= Rs. 240000 per Year.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description of the seat frame structure in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

Although the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification.
A person skilled in the art may make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
All such changes, variations, modifications, alterations and/or integrations in terms of materials and method used in configuring, manufacturing and assembling the novel seat frame structure adopted and arrived by any such skilled person are also comprised and embraced within the scope and spirit of the present invention, whereby it shall be distinctly understood that the entire foregoing description and figures are treated merely illustratively and exemplarily and not as a limitation of the present invention.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. A device for checking the working of a defogger coil in motor vehicles, wherein the device comprises an 'L' shaped configuration having a positive terminal and a negative terminal for checking the functioning of defogger coils in different variants and models of the motor vehicles.
2. Device as claimed in claim 1, wherein the device comprises a short leg and a long leg; both the legs are connected to each other by means of a hinged joint.
3. Device as claimed in claim 1, wherein the positive terminal is configured at the shorter leg end and the negative terminal is configured at the longer )eg end thereof; both the legs adapted to be connected to each other by means of a hinged joint for checking the defogger functioning of different variants and models of the motor vehicles.
4. Device as claimed in claim 1, wherein the longer leg includes an indicator bulb substantially in the middle portion thereof for testing the continuity of the electrical circuit of the defogger coil.
5. Device as claimed in claim 1, wherein the negative terminal is made of scrap materials available in-house.
6. Device as claimed in claim 1, wherein the positive terminal is made from wheel nuts available in-house.
7. Device as claimed in claim 1, wherein the testing lamp fitted in the middle of the longer leg of the device are retrieved from the scrap available in-house.

8. Method of checking the defogger of a motor vehicle using the device as claimed in any of the claims 1 to 7, wherein said method comprises the following steps:
- dismounting from the motor vehicle;
- ensuring that the Ignition switch is ON;
- keeping the Defogger switch ON (confirming the defogger switch condition by keeping illumination light ON);
- taking said defogger checking device from the stand thereof and moving to the rear side door of the motor vehicle;
- opening the right side door of the motor vehicle and connecting the positive terminal of said defogger checking device to the positive terminal near the right side connector of the windshield glass and the negative terminal of said defogger checking device to any coil on the windshield glass on the left side;
- checking the glowing status of the bulb provided on said defogger checking device;
wherein a non-glowing bulb status indicates a defect in the electrical circuit of the defogger coil and a glowing bulb status indicates a properly functioning defogger coil of the motor vehicle.