This disclosure generally relates to temperature-regulation in automobiles, and in particular relates to automatic temperature control within the vehicle-cabin.

Background

The present subject matter relates to automobile air-conditioners, and more particularly to an electric control method for an automobile air conditioner, in which an electronic control unit (ECU) of the vehicle may be employed to direct and maintain the actual in-car temperature towards and within a desired value.

State of the art temperature sensing and regulation mechanisms in automobile cabin involve sampling air temperature at one or more predetermined position within the vehicle cabin. Accordingly, air conditioning is performed such that the temperature within the vehicle cabin becomes equal to a preset-temperature. As a device for detecting the air and environment temperature within the vehicle cabin, an in-car sensor equipped with an aspirator fan motor is known. This in-car sensor equipped with an aspirator fan motor comprises a thermistor as a temperature-sensing element and an aspirator for forcibly drawing air from a predetermined position within the vehicle cabin to the thermistor. The aspirator comprises an aspirator-fan for introducing air from the vehicle cabin to the thermistor, and a motor for driving the aspirator fan.

Under conditions, the aforesaid in-car temperature regulation may be influenced by ambient conditions. For example, if the ambient temperature is low and it is cold outside, then the cabin-temperature may not be lowered much despite the in-car sensor sensing a high cabin temperature. Likewise, an extremely low temperature sensed by the in-car sensor within the cabin does not lead to a temperature rise in case the ambient-conditions outside are already hot.

While there exists embedded systems within the automobile to electronically and automatically regulate the cabin temperature, this lies a need to efficiently, accurately and timely arrive at a desired cabin-temperature.

More specifically there lies a need of time-efficient and accurate in-car temperature regulation mechanisms without any overhead of manufacturing complexity and added-costs.
Summary

This summary is provided to introduce a selection of concepts in a simplified version that is further described below in the detailed description. This summary is not intended to identify key features or essential features of the present invention, nor is it intended as an aid in determining the scope of the present invention.

As known in the state of the art, vehicle-temperature is controlled on the basis of temperatures sensors as one of the factors. For the interior temperature measurement, a sensor is equipped within the vehicle so that it can display the cabin temperature. Also, other types of sensors such as ambient sensors are provided for ambient temperature measurement (i.e. outside the car) to further help in maintenance of in-cabin temperature.

The present subject matter refers a sensing device for an enclosed environment comprising a first sensor for measuring light intensity and an external temperature. A second sensor measures an internal temperature. An ADC is provided for converting measured light intensity and temperature values by the first and second sensor into one or more equivalent voltages corresponding to digital levels. A microcontroller is configured for reading the one or more voltages from the ADC converter. The one or more voltages of the first and second sensor are converted into the temperature values associated with the first and the second sensor. Based on comparing between the temperature values of the first sensor with the second sensor, a desired temperature value is computed for enclosed environment based on processing of the temperature values of the first sensor and the second sensor through a selected criteria.

At least in accordance with an embodiment of the present subject matter, the regulation of the temperature comprises temperature regulation based on consideration of temperature due to sun light (outside the car environment) and car-cabin. In an implementation, the present subject matter derives a compensated value of temperature based on the difference in both type of measured temperatures. As may be understood, the present subject matter advantageously measures the temperature of car cabin through an in-car temperature sensor (NTC) base sensor and the temperature due to the light-intensity through a photo diode based sensor. In an implementation, the NTC is incorporated with photodiode. Temperature sensor (NTC) measures cabin temperature and the photodiode measures the rise of temperature due to the light intensity for facilitating actual temperature management within the car-cabin

The advantages and details of the present invention will be apparent from the following detailed description and accompanying drawings, which are explanatory only and is not restrictive of the present invention.

Brief Description of the Accompanying Drawings

To further clarify the advantages and features of the present invention, a more particular description of the present invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the present invention and are therefore not to be considered limiting of its scope. The present invention will be described and explained with additional specificity and detail with the accompanying drawings in which:

Figure 1 illustrates a perspective view of a combined assembly of NTC-1, NTC-2 sensors as an integrated unit, in accordance with the present subject matter;

Figure 2 illustrates an exploded view of an in-car temperature sensor PCB assembly in accordance with the present subject matter;

Figure 3a illustrates block diagram representation of interfacing of sensor and microcontroller unit in accordance with the present subject matter,

Figure 3b illustrates a schematic view for interfacing of sensor and microcontroller unit based on voltage measurement across the NTC sensors within the integrated unit, in accordance with the present subject matter;

Figure 4 illustrates a block-diagram representation depicting relevant parameters for the conversion of sensor raw value to actual temperature, in accordance with the present subject matter;

Figure 5a illustrates an equivalent flow diagram for process the raw sensor value to the actual temperature value, in accordance with the present subject matter;

Figure 5b illustrates a computational module for computing the desired temperature value, in accordance with the present subject matter;

Figure 6 illustrates the curve of the NTC sensor with respect to temperature and voltages, in accordance with the present subject matter; and

Figure 7 illustrates a graphical representation corresponding to the temperature value change of NTC1, NTC2 in accordance with the present subject matter.

It may be noted that to the extent possible like reference numerals have been used to represent like elements in the drawings. Further, those of ordinary skill in the art will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of aspects of the present invention. Furthermore, the one or more elements may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefits of the description herein.

Detailed Description Drawings

For the purpose of promoting an understanding of the principles of the present invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the present invention and are not intended to be restrictive thereof. Throughout the patent specification, a convention employed is that in the appended drawings, like numerals denote like components.

Reference throughout this specification to “an embodiment”, “another embodiment” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

Various embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Figure 1 illustrates a perspective view of a combined assembly of NTC-1, NTC-2 sensors as an integrated unit, in accordance with the present subject matter. More specifically, Figure 1 illustrates a perspective view of sensor module 100 to interface with a main control unit (not shown in diagrams), according to an embodiment of present matter. The sensor module 100 may be interchangeably referred to measuring the Vehicle in-cabin environment temperature measurement. The sensor module 100 may include a NTC + IR Sensor 101, to make contact with the main control unit with using connector pin referred by two sets 102 & 103. The sensor module 100 may be configured to transmit signal to the main control unit or controller unit based on the vehicle in-cabin temperature.

More specifically, the sensor module 100 of Fig 1 illustrates the in-car sensor having NTC incorporated with photodiode. Another NTC sensor (shown in Fig. 2) is provided as surface mount thermistor or the NTC sensor integral to a PCB circuit, i.e. PCB_Cp mounted NTC. In another embodiment, an IR sensor may also be integral to the PCB circuit as surface mount sensor and thereby assist the determination of temperature alongwith PCB_Cp mounted NTC. The in-car sensor of Fig. 1 is mounted at a strategic-position in the car so both type of temperature reading, i.e. both NTC sensing and photo-diode sensed readings are feasible. As the value of photocurrent and NTC-voltage is measured, the same are communicated to a processing unit or a microcontroller (shown IN Fig. 3a). Moreover, as clearly seen from Fig. 1, the connections of both the IR sensor and NTC thermistors, are isolated from each other as a set of different pins 103. In other words, the NTC + IR and other NTC are connected separately to the microcontroller. Moreover, the in-car sensor comprises terminals defined by the set of pins 102 for connecting to power-supply (+5V) and ground.

In an example and as a part of the PCB arrangement, a differential signalling system may be adopted, where a signal is transmitted down a pair of tightly coupled carriers, one of these carrying the signal, the other carrying an equal but opposite image of the signal. Differential pair PCB routing is a design technique employed to create a balanced transmission system able to carry differential (equal and opposite) signals across a printed circuit board. As one of advantages of differential pairing, noise is subtracted away.

Figure 2 illustrates the exploded view of the In-cabin Temperature sensor module 100 (an in-car temperature sensor PCB assembly), according to an embodiment of the present subject matter. As mentioned earlier, the sensor module 100 may include the NTC + IR Temperature sensor 200 referred as NTC-1 or the first sensor 200 for measuring external temperature. Further, the sensor module may include other NTC sensor as NTC – 2 or the second sensor 202 for measuring internal temperature. In another embodiment, an IR sensor may also be integral to the PCB circuit as surface mount device and thereby act as further sensor within the NTC – 2 or the second sensor 202. Both of the sensors 200, 202 may be encapsulated separately as different components in a housing assembly 201. An arrangement 203 is further provided within the assembly 201 to supports the pins 102, 103 within the sensor module 100.

The sensor module 100 may include, but is not limited to NTC + IR Temperature sensor 200, housing assembly 201 & 203 & NTC – 2 202. The first sensor 200 is an assembly of an NTC sensor and an IR sensor (NTC-1) and disposed externally, and wherein the second sensor 202 is an NTC sensor (NTC-2) integral to the printed circuit board (PCB) and disposed internally.

The sensor module 100 may be attached to the main control unit (not shown in figures) for sensing the control unit internal and environment temperature. In an example, if the user switches on a mode for the control unit to operate temperature dependent functions, the control unit or the microcontroller will initially detect or sense the temperature in raw value (e.g. as Digital signals). Thereafter, the control unit derives the actual temperature values from the raw values as per recommended datasheet, subjects the derived temperature values to predefined processing functions based on predefined formulas.

Figure 3a illustrates block diagram representation of interfacing of sensor module 100 and the microcontroller unit 305, according to an embodiment of the present subject matter. The sensor module 100 may include a connector 300 to make connections with the main control unit (Not shown in drawings), Power supply +5 volt 304, and interfacing signals with microcontroller as 301, 302, and 303, microcontroller unit 305, without departing from the scope of the present subject matter. The sensor module 100 may include, but is not limited to, the housing assembly 201 for encapsulating various components as depicted in Fig. 2. The connector 300 is also provided for mutually insulating the terminals 102, 103 of the first sensor 200, the second sensor 202, the power supply and ground.

Figure 3b illustrates an equivalent circuit for voltage measurement across the NTC sensor, in accordance with the present subject matter. In an embodiment, NTC + IR-sensor signal 307 & 308 respectively, NTC-2 signal 309, upon filtering through a filtering circuit (310-314) are converted into a low current analog signal 312, 313, 314. In an example, the filtering circuit may be an RC filtering circuit. The analog signals 312, 313, 314 are connected with an ADC Channel of microcontroller 305. The sensors 307, 308 are mounted over a PCB module (not shown in figures), and the connector 300 is also mounted over the module’s 100 PCB-CP. The shown components in Fig. 3b are example in nature and are connected to the control unit. However, the same may be construed to cover analogous components as known in state of art.

In an example, the circuit Fig. 3b is triggered by a 5-volt input or Vcc as the common power-supply provided at the ‘terminal 4’ for the photo-diode + NTC sensor (i.e. NTC-1) and NTC-2. The terminal 5, terminal 3 and terminal 2 respectively represent the output-voltage as generated by the photodiode + NTC sensor (i.e. NTC-1) and NTC - 2. The analog-output from terminals 5, 3 and 2 are communicated to the micro-controller in Fig. 3(b) via the ADC. In other words, the low current analog signal is communicated to the ADC converter for further communicating to the microcontroller (305). In an example, the ADCs correspond to a high value shunt resistor acting as the current to voltage converter. Other example of ADC may be flash, successive-approximation, and sigma-delta.
In operation, inside and outside temperature is measured by NTC-1 and NTC-2. For outside, the IR property of the sensor NTC-1 is used. The photodiode sensor-arrangement of NTC-1 in the vehicle is configured to detect the sunlight and energized/Heated up proton packets directly. The photodiode takes the sunlight as an input and renders current in terms of output (e.g. as nano-ampere current). As photodiode works in reverse bias, when light is incident on the photodiode, the output photocurrent and voltage is low. Such low value current, which may be a nano ampere current, is driven through the high value shunt resistor for conversion into a corresponding voltage that meets a standard voltage (or Rail to Rail voltage). Such standard voltage corresponds to a digital level and accordingly the operation of high value shunt resistor may be referred as an analog to digital converter or ADC. The standard voltage is further transmitted to the microcontroller of Fig. 3b. In other optional embodiment, the low value current may be alternately amplified by the operational amplifier acting as the ADC. With increasing the gain, the output value of the Op-Amp voltages meet the standard voltage (or Rail to Rail voltage) that may be transmitted to the microcontroller of Fig. 3b. The standard voltage as obtained is coupled to the microcontroller and enables calculation of the value of the compensated temperature based on the ADC count. Overall, the ADC converter converting the measured light intensity and temperature values by the first sensor 200 and the second sensor 202 into one or more voltages corresponding to digital levels.

The NTC-2 sensor is also triggered by 5-volt input or Vcc as the common power-supply provided by terminal 4, 309. The NTC-2 sensor senses the inside temperature of PCB-Cp, which may be heated by component operations. The NTC-2 internal resistance fluctuates on changing the environment temperature. As earlier described, that changes of resistance can be observed by microcontroller unit 305.

In an example, the electronic circuit of the NTC-1 (307) and NTC-2 (309) sensor comprises a 5-volt input or Vcc as the common power-supply. The thermistor is an electrical-resistor whose resistance reduces upon heating. A pull down resistance configuration may be used to determine the equivalent-voltage (Veq) or Output voltage (Vout) at the Terminal 3 of both of NTC-1 and the NTC-2. With respect to different values of resistance in the NTC sensor that undergoes variation with change in temperatures, the different voltages are calculated with the help of a standard Resistance/Temperature (R/T) table associated with the thermistor.

In operation, the Vout with respect to the NTC’s (307 & 309) sensor is digitized (through analog to digital converter) as per standard values based on the high value shunt resistor for conversion into the corresponding voltage that meets a standard voltage (or Rail to Rail voltage) that may be further transmitted to the microcontroller of Fig. 3b .. In order to meet the required threshold of the standard voltage in accordance with the ADC, the low voltage drop due to nano-ampere current is amplified into a high output-voltage “Vout” by employing a high value of resistance at the output to obtain a measurable voltage detectable by the microcontroller. Thereafter, the standard digital values as obtained are coupled to the microcontroller and leads to calculation of the value of the compensated temperature or a desired temperature value based on the ADC count.

Figure 4 illustrates a block-diagram representation depicting relevant parameters for conversion of sensor raw value to actual temperature, in accordance with the present subject matter. More specifically, Fig. 4 illustrates any Block diagram for complete temperature measurement and compensation system.

At step 400, Temperature sensor NTC-1 and NTC-2 measures temperature value (analog) in the sensor module 100. The analog values are converted into digital levels through the ADC conversion as depicted in Fig. 3b. In addition, values from other state-of-the art sensors such as ambient temperature sensors (LDR), solar sensor, evaporator sensor data etc may be used as miscellaneous sensor data to supplement the values provided by the present sensor 100.

At step 401, the microcontroller reconverts the received digital values into temperature values. Thereafter, the microcontroller executes a computation module to select an appropriate criterion for conversion of the temperature values.

At step 402, based on the criterion selection, a temperature compensation is performed and final compensated temperature values are obtained as a result.

Figure 5 illustrates an equivalent flow diagram for process the raw sensor value to the actual temperature value and a computational module for computing a desired temperature value, in accordance with the present subject matter.

Specifically, Figure 5a illustrates a method 500 for measuring the signal from sensor module 100 upon having been triggered by the power supply.

At step 501, the input voltages or power supply Vcc triggers the operation of the sensor NTC-1 and NTC-2 as depicted before. The triggering activates the sensors NTC-1 and 2 with respect to the main control unit. The filtering circuit 310-314 of Fig. 3b is provided for filtering the temperature values obtained from the NTC-1 or the first sensor 200 and the NTC-2 or the second sensor 202 for converting into a low current analog signal. In another embodiment, the IR sensor may also be integral to the PCB circuit as surface mount device and thereby act as further sensor within the NTC – 2 or the second sensor 202 to assist temperature compensation.
At step 502, the analog values determined in the Step 501 and corresponding to currently determined temperature from the sensor module are converted into digitized values based on the implementation in Fig. 3a and Fig. 3b through the ADC conversion. In operation, the Vout with respect to the NTC sensor as obtained in step 501 is digitized as per standard values by the operational amplifier acting as the ADC. Therefrom, the standard values as obtained are read by the microcontroller and leads to the calculation of the value of the compensated temperature based on the ADC count later in step 507.
At step 503, the method 500 includes identifying a raw value of the ADC counts and reconversion back into the temperature values for all connected sensors NTC-1 and NTC-2.

At step 504, the method 500 includes comparing the generated temperature of NTC-1 and NTC-2 as obtained in step 503 to determine inequality there-between. Based on such comparison, the microcontroller decides estimating a more accurate temperature based on following steps 505 and 506.

At step 505, if the comparison in step 504 meets the condition NTC – 1 < NTC – 2, then the falling temperature criteria 609 and coefficient is selected as provided in Fig. 5b. Such criteria may be defined as
Falling/Cooling temp. = x2*internal temp + y2*external temp + z2-------(509)

At step 506, if the comparison in step 504 meets the condition NTC - 1 > NTC – 2, then a rising temperature criteria 608 and co-efficient is selected as provided in Fig. 5b. Such criteria may be defined as
Rising/Heating temp. = x1*internal temp + y1*external temp + z1-------(508)

Here in equations 508 and 509, NTC1 is the External temperature and the NTC2is Internal temperature. Further, x1 and y1 are the coefficients computed in real time and z1,z2 represent the constants in equations 508 and 509.

At step 507, a desired temperature value is computed for the enclosed environment such as the in car temperature based on processing of the temperature values of the NTC - 1 or the first sensor and the NTC – 2 or the second sensor through the selected criteria.

Figure 6 illustrates the curve of NTC sensor with respect of temperature and voltages, in accordance with the present subject matter. Specifically, Figure 6 illustrates the sensor data read by the NTC1, NTC2, ambient temperature with the help of thermocouple, calculated values achieved by the formula for rising 508 and falling 509 for accurate compensated values which will follow the ambient real time values. Real time samples are taken for ambient temperature measurement, in an example from a thermocouple. NTC1 sensor 601 senses the value outside the casing or sensor module 100 and NTC2 senses the temperature value inside the casing 600 of the sensor module 100. Real-time ambient temperature sensing is done with the help of thermocouple 602.

After compensation of temperature value read by the NTC1 601 & NTC2 600 using the formula for the rising criteria 506 and falling criteria 505, the calculated temperature which also points to the desired temperature or the compensated temperature is shown under the column 603. The difference between the ambient temperature calculated values 602 calculated by the thermocouple and the calculated temperature values 603 in accordance with the steps 505 and 506 is shown as a “difference” through the column 604.

Figure 7 illustrate the graph corresponds to the temperature values change of NTC1, NTC2, Ambient value by the thermocouple sensor, calculated value by the rising and falling formula and the differences of ambient and calculated values.

NTC2 (blue color) temperature value 700 reading variations shown in graph. NTC1 (orange color) temperature value 701 reading variation has been shown in graph. Thermocouple based Ambient temperature sensor reading 702 is shown in graph with gray color. Calculated values using the formula for rising and falling temperature are shown in graph with yellow color 703.
As may be observed from Fig. 7 and Fig. 6, when compared with the calculation of actual ambient temperature and based on a data-analysis for compensation of the ambient temperature, the calculated result of temperature data is observed as substantially close to the actual ambient values.
The rate of change and the way of temp raising and falling is observed and based thereupon the rising and falling temperature criteria for accurate measurement is employed. The coefficient values in the rising 506 and falling 505 temp criteria are computed in real time and accordingly vary on case to case basis. A resultant compensated temperature-value is calculated by a compensation-logic in the microcontroller, wherein the compensated temperature value is computed based on the prevailing in-car temperature and ambient temperature that is determined due to prevailing light intensity (e.g. light intensity due to sunshine). Overall, the sensor module 100 is enabled to operate in any changing ambient temperature with robustness and accuracy of results.
Based on aforesaid sensor data collected, the microcontroller 305 incorporates a control procedure as depicted in steps 502 till 506 for an automobile air conditioner in which a digital computer is utilized to calculate a value required to direct the actual in-car temperature toward a desired value or a compensated value in consideration with various changes of ambient temperature. In an example, the calculated value is compensated to effectively reduce a difference between the actual in-car temperature and the desired value when the rate of change of the actual in-car temperature becomes below a predetermined value.

Overall, the present subject matter provides an in-car sensor that enables measurement of the temperature of car cabin as well as temperature of light intensity due to sun. The same is at least facilitated by the incorporation of NTC with photodiode. As the value of photocurrent and NTC voltage is measured, it is sent to processing unit. A compensated temperature value is calculated by a temperature compensation logic which is executed by the processor.

Embodiments of the present invention have been described in detail for purposes of clarity and understanding. However, it will be appreciated that certain changes and modifications may be practiced within the scope of the present invention. Thus, although the present invention is described with reference to specific embodiments and drawings thereof, the embodiments and drawings are merely illustrative, and not limiting of the present invention.

We Claim:

1. A sensing device (100) for an enclosed environment comprising:
a first sensor (200) for measuring at least one of light intensity and an external temperature;
a second sensor (202) for measuring an internal temperature;
an ADC converter for converting measured light intensity and temperature values by the first (200) and second sensor (202) into one or more voltages corresponding to digital levels;
a microcontroller (305) configured for:
reading (502) the one or more voltages from the ADC converter;
converting (503) the one or more voltages of the first and second sensor into the temperature values associated with the first and second sensor;
comparing (504) the temperature value of the first sensor with the second sensor;
select (505, 506) a criteria out of a plurality of criteria based on said comparison; and
computing (508) a desired temperature value for enclosed environment based on processing of the temperature values of the first sensor and the second sensor through the selected criteria.

2. The sensing device (100) as claimed in claim 1, wherein the first sensor (200) is an assembly of an NTC sensor and an IR sensor (NTC-1) and disposed externally, and wherein the second sensor (202) is an NTC sensor (NTC-2) integral to a printed circuit board (PCB) and disposed internally.

3. The sensing device (100) as claimed in claim 2, wherein the NTC sensor (NTC-2) is powered by a 5-volt input (VCC ) power-supply and comprises:
a thermistor;
a pull down resistance to determine the equivalent-voltage or Output voltage, and
wherein the second sensor 202 further comprises an IR sensor integral to the PCB.

4. The sensing device (100) as claimed in claim 1, further comprising:
a filtering circuit (310-314) for filtering the temperature values obtained from the first (200) and the second sensor (202) for converting into a low current analog signal, wherein the filtering circuit (310-314) is an RC filtering circuit; and
communicating the low current analog signal to the ADC converter for further communicating to the microcontroller (305).
5. The sensing device (100) as claimed in claim 1, further comprising:
a connector (300) for mutually insulating the terminals (102, 103) of the first sensor (200), the second sensor (202), the power supply and ground.
6. The sensing device (100) as claimed in claim 1, wherein comparing the temperature value of the first sensor (200) with the second sensor (202) by the microcontroller (305) comprises determining inequality between the temperature values of the first sensor (200) and the second sensor (202).
7. The sensing device (100) as claimed in claim 1, wherein selecting the criteria out of the plurality of criteria by the microcontroller (305) comprises:
selecting (506) a rising temperature criteria if the calculated temperature of the first sensor (200) exceeds the second sensor (202).
8. The sensing device (100) as claimed in claim 1, wherein selecting the criteria out of the plurality of criteria by the microcontroller comprises:
selecting (505) a falling temperature criteria if the calculated temperature of the second sensor (202) exceeds the first sensor (200).
9. The sensing device (100) as claimed in claims 7 and 8, wherein computing the desired temperature value for enclosed environment by the microcontroller (305) comprises:
computing the desired temperature value based on the processing of the temperature values of the first sensor (200) and the second sensor (202) through the rising temperature criteria (506) or the falling temperature criteria (505).
10. A method of operation of a sensing device (100) for an enclosed environment comprising:
Measuring (501) at-least one of light intensity and an external temperature by a first sensor (200);
Measuring (501) an internal temperature by a second sensor (202);
Converting (501) measured light intensity and temperature values by the first (200) and second sensor (202) into one or more equivalent voltages corresponding to digital levels;
reading (502) the one or more voltages from the ADC converter;
converting (503) the one or more voltages into of the first (200) and the second sensor (202) into the temperature values associated with the first and second sensor;
comparing (504) the temperature value of the first sensor (200) with the second sensor (202); and
selecting (505, 506) a criteria out of a plurality of criteria based on said comparison;
computing (507) a desired temperature value for enclosed environment based on processing of the temperature values of the first sensor (200) and the second sensor (202) through the selected criteria.