FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“AN INTERFACE CIRCUIT FOR MAINTAINING AIR DELIVERY VOLUME OF A CEILING FAN”
We, Bajaj Electricals Limited, an Indian National, of 45/47, Veer Nariman Road, Fort, Mumbai- 400001, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present disclosure relates to the field of consumer electronics, in particular, ceiling fans. More particularly, the disclosure relates to an interface and method for controlling the air delivery volume.
BACKGROUND OF THE INVENTION
This section is intended to provide information relating to the field of the invention and thus, any approach or functionality described below should not be assumed to be qualified as prior art merely by its inclusion in this section.
Ceiling fans are conventionally hung from a ceiling to provide air flow in a radially downward direction. Conventional ceiling fan are known to employ a motor and a plurality of fan blades mounted on the said motor, wherein the said motor is employed to provide rotational motion therein. Conventional ceiling fans are enabled to operate at a one or more pre-defined speeds to deliver a pre-determined volume of air.
During installation/uninstallation, wear and tear under normal conditions, the angle of one or more blades of the ceiling fan may deviate from the original configuration and/or the shape of the blade may distort, thereby effecting the air delivery volume. In the event the angle of the blade increases, the air delivery volume increases due to the increased surface area, which also leads to higher energy consumption due to increased air resistance. Conversely, the air delivery volume decreases as angle of the blade decreases, leading to reduced energy consumption due to reduced air resistance. In both cases, the change in air volume delivery is an inconvenience to the user and the operation of the ceiling fan is compromised.
Therefore, there is a need in the art to overcome the aforesaid limitation(s) to provide for maintaining the desired intended air delivery volume as a function of time that can accommodate changes in the angle of the ceiling fan blade.

SUMMARY OF THE INVENTION
This section is intended to introduce certain objects of the disclosed method and system in a simplified form, and is not intended to identify the key advantages or features of the present disclosure.
In an aspect of the present invention, there is provided an interface circuit for maintaining air delivery volume per unit time of a ceiling fan comprising: a detection module to detect at least an input current from an output of an AC/DC SMPS (switch mode power supply) of the ceiling fan; a comparison module to compare the input current with at least a pre-defined current to provide a weighted current; and a transmission module to transmit the weighted current to a motor controller electrically connected to a fan motor for maintaining air delivery volume per unit time.
In another aspect of the present invention, the interface circuit comprises a hardware memory module, wherein the hardware memory module is adapted to transiently store the weighted current, said weighted current is equal to the value transmitted to the motor controller.
In yet another aspect of the present invention, the hardware module is adapted to transmit a stored pre-defined current by the transmission module, or the weighted current to the motor controller upon initialization of a power on cycle.
In yet another aspect of the present invention, the interface module comprising detection module, comparison module, and transmission module are provided in a single unit.
In yet another aspect of the present invention, the detection module, comparison module and transmission module are individual units interconnected with each other.
In still another aspect of the present invention, the AC/DC SMPS (switch mode power supply) [102] comprises a step-down DC voltage converter and AC/DC converter.

In another aspect of the present invention, there is provided a method for maintaining air delivery volume per unit time of a ceiling fan upon initialization of a power on cycle, said method comprising: (a) fetching at least a stored pre-defined current or a weighted current stored in a hardware memory module; and (b) transmitting the pre-defined current or the weighted current from the hardware memory module to a motor controller electrically connected to a fan motor via transmission module; wherein said hardware memory module is comprised in an interface circuit as claimed in claim 1, said interface circuit comprising: a detection module to detect at least an input current from an output of an AC/DC SMPS (switch mode power supply) of the ceiling fan; a comparison module to compare the input current with at least a pre-defined current to provide weighted current; and a transmission module to transmit the weighted current to a motor controller electrically connected to a fan motor for maintaining air delivery volume per unit time.
In yet another aspect of the present invention, the method for maintaining air delivery volume per unit time of a ceiling fan upon initialization of a power on cycle, further comprises a default value transiently stored in the hardware memory module, wherein the default value is a pre-defined current or a weighted current
In yet another aspect of the present invention, there is provided a method for maintaining air delivery volume per unit time during operation of a ceiling fan, said method comprising: (a) detecting by a detection module at least an input current from an output of an AC/DC SMPS (switch mode power supply) of the ceiling fan; (b) comparing the input current with at least a pre-defined current in a comparison module to provide a weighted current; and (c) transmitting by a transmission module the weighted current to a motor controller electrically connected to a fan motor, wherein the speed of the ceiling fan is varied to maintain air delivery volume per unit time; and the detection module, comparison module, and the transmitting module are comprised in an

interface circuit, said interface circuit comprising: a detection module to detect at least an input current from an output of an AC/DC SMPS (switch mode power supply) of the ceiling fan; a comparison module to compare the input current with at least a pre-defined current to provide a weighted current; and a transmission module to transmit the weighted current to a motor controller electrically connected to a fan motor for maintaining air delivery volume per unit time.
In yet another aspect of the present invention, the method for maintaining air delivery volume per unit time during operation of a ceiling fan further comprises an interface circuit, wherein memory hardware of the interface circuit transiently stores a weighted current.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In order to explain the technical solution in the embodiments of the present application more clearly, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application. For those skilled in the art, without any creative work, other drawings can be obtained based on these drawings.
It is to be noted, however, that the appended drawings only illustrate typical embodiments of the present subject matter, and are therefore, not to be considered for limiting of its scope, for the subject matter may admit to other equally effective embodiments.
FIG. 1 illustrates a system architecture of an interface circuit for maintaining air delivery volume per unit time of a ceiling fan, in accordance with embodiments of the present invention.
FIG. 2 illustrates an exemplary flow diagram of a method of maintaining air delivery volume per unit time upon initialization of a power on cycle, in accordance with embodiments of the present invention.

FIG. 3 illustrates an exemplary flow diagram of a method of maintaining air delivery volume per unit time during operation of a ceiling fan, in accordance with embodiments of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent, however, that embodiments of the present invention may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address any of the problems discussed above or might address only one of the problems discussed above.
Some of the problems discussed above might not be fully addressed by any of the features described herein. Exemplified embodiments of the present invention are described below, as illustrated in various drawings in which like reference numerals refer to the same parts throughout the different drawings.
The present invention provides an interface circuit [106] comprising: (a) a detection module [108] to detect at least an input current from an output of an AC/DC SMPS (switch mode power supply) [102] of the ceiling fan [100]; (b) a comparison module [110] to compare the input current with at least a pre¬defined current to provide a weighted current; and (c) a transmission module [112] to transmit the weighted current to a motor controller [116] electrically connected to a fan motor [118] for maintaining air delivery volume per unit time.
In an embodiment, the interface circuit [106] further comprises a hardware memory module [114] adapted to transiently store the weighted current, said weighted current is equal to the value transmitted to the motor controller [116]. The hardware memory module [114] is adapted to transmit a stored pre-defined current or a weighted current by the transmission module [112], to the motor controller [116] upon initialization of a power on cycle.

In a preferred embodiment, the interface circuit [106] comprises: (a) a detection module [108] to detect at least an input current from an output of an AC/DC SMPS (switch mode power supply) [102] of the ceiling fan [100]; (b) a comparison module [110] to compare the input current with at least a pre¬defined current to provide a weighted current; (c) a transmission module [112] to transmit the weighted current to a motor controller [116] electrically connected to a fan motor [118] for maintaining air delivery volume per unit time; and (d) a hardware memory module [114] adapted to transiently store the weighted current, said weighted current is equal to the value transmitted to the motor controller [116]. The hardware memory module [114] is adapted to transmit a stored pre-defined current or a weighted current by the transmission module [112], to the motor controller [116] upon initialization of a power on cycle.
In an embodiment, the interface circuit [106] comprising the detection module [108], comparison module [110], and transmission module [112] are provided in a single unit. In another embodiment, the detection module [108], comparison module [110], and the transmission module [112] are individual units interconnected with each other.
In an embodiment of the present invention, the AC/DC SMPS (switch mode power supply) [102] device comprises a step-down DC voltage converter [104] and AC/DC converter.
The present invention also provides a method for maintaining air delivery volume per unit time of a ceiling fan [100] ] upon initialization of a power-on cycle, the method comprising: a) fetching at least a stored pre-defined current or a weighted current stored in a hardware memory module [114]; and b) transmitting the pre-defined current or the weighted current from the hardware memory module [114] to a motor controller [116] electrically connected to a fan motor [118] via a transmission module [112]; wherein the hardware memory module [114] is comprised in an interface circuit [106]. The interface circuit [106]

is as substantially described in the present specification.
In an embodiment, the pre-defined current is a default value transiently stored in the hardware memory module [114]. In another embodiment, the weighed current is a default value transiently stored in the hardware memory module [114].
The present invention also provides a method for maintaining air delivery volume per unit time during operation of a ceiling fan [100], said method comprising: a) detecting by a detection module [108] at least an input current from an output of an AC/DC SMPS (switch mode power supply) [102] of the ceiling fan [100]; b) comparing the input current with at least a pre-defined current in a comparison module [110] to provide a weighted current; and c) transmitting by a transmission module [112] the weighted current value to a motor controller [116] electrically connected to a fan motor [118], wherein the speed of the ceiling fan [100] is varied to maintain air delivery volume per unit time.
In an embodiment, the detection module [108], comparison module [110], and the transmission module [112] are comprised in an interface circuit [106]. The interface circuit [106] is as substantially described in the present specification. In a preferred embodiment, the interface circuit [106] further comprises a hardware memory module [114] as substantially described herein.
In an embodiment, the weighted current is transiently stored in the memory hardware module [114] comprised in the interface circuit [106] during operation of the ceiling fan [100].
In a preferred embodiment, the interface circuit comprising the detection module [108], comparison module [110], and transmission module [112] are provided in a single unit. In another preferred embodiment, the detection module [108], comparison module [110], and transmission module [112] are individual units interconnected with each other.

Fig 1. illustrates the system architecture of the interface circuit [106] for maintaining air delivery volume per unit time of a ceiling fan [100] of the present invention. The ceiling fan [100] is a conventionally known fan that is mounted from a ceiling to provide air flow in a radially downward direction. The ceiling fan [100] (not shown) comprises a fan assembly [102] (not shown) controlled by a control unit, wherein the control unit is employed to drive the fan assembly [102]. The fan assembly [102] comprises a fan motor [118] and a plurality of fan blades, wherein the plurality fan blades are mounted on the circumference of the fan motor [118]. The fan motor [118] drives the plurality of fan blades in a clockwise motion thereby delivering air flow in a radially downward direction. A structure and arrangement of the control unit will be described hereinafter in detail. CONTROL UNIT
The control unit is employed to control various parameters of the fan motor [118] such as input current and speed of the fan motor [118] to provide maintained air delivery per unit time. The control unit comprises an Alternating Current/Direct Current Switch Mode Power Supply (AC/DC SMPS) module [102], which includes a Step down DC voltage converter [104] (not shown) and an interface circuit [106], wherein the AC/DC SMPS module [102] is electrically connected to an alternating current (AC) power source. AC/DC SMPS
The AC/DC SMPS [102] is an electrical device that is employed to convert the input alternating current from an AC power source into direct current (DC) to provide the fan motor [118] with the stable current. The AC/DC SMPS [102] device comprises step-down DC voltage converter [104] (not shown) and AC/DC converter. Further the step-down DC voltage converter [104] is electrically connected to the AC/DC convertor [102]. The step-down DC voltage converter [104] reduce the voltage received from the AC/DC converter to the required voltage. Further, the step-down DC voltage converter [104] is electronically

connected to the interface circuit [106], wherein the interface circuit [106] detects an input current and compares it with a predefined current to provide a weighted current. ‘Weighted current’ refers to the current to be transmitted to the fan motor [118]. INTERFACE CIRCUIT
The interface circuit [106] is essentially a microcontroller that performs the necessary operations of the control unit. For example, the interface circuit [106] is a microcontroller electronically communicating with a detection module [108], a comparison module [110], a hardware memory module [114], a transmission module [112], and a motor controller [116], wherein the control circuit is deployed to maintain air delivery volume per unit time. In a preferred embodiment the interface circuit [106] is a single module, wherein the micro¬controller includes the detection module [108], the comparison module [110], the hardware memory module [114], the transmission module [112], and the motor controller [116] as one unit. In another embodiment, the detection module [108], the comparison module [110], the hardware memory module [114], the transmission module [112], and the motor controller [116] are individual modules electronically connected therein. For ease in reference and understanding, the interface circuit [106] will be described for a single module however, a similar functioning and arrangement of the multiple modules of the interface circuit [106] may be envisioned by a person skilled in the art. DETECTION MODULE
The detection module [108] employed for detecting at least an input current from an output of the step-down DC voltage converter [104] of the switch mode power supply [102]. The detection module [108] electronically connected to the comparison module [110] and the transmission module [112], wherein the detection module [108] electronically transmits the input current to the comparison module [110] as well as the transmission module [112]. Upon initialization, the transmission module [112] retrieves any one of a pre-defined

current, and a weighted current and transmits any one of the said pre-defined
current and the said weighted current to the motor controller [116]. ‘Pre-defined
current’ refers to default value stored within the hardware memory module
[114].
COMPARISON MODULE
The comparison module [110] electronically connected to the detection module [108] wherein the comparison module [110] compares the input current with at least a pre-defined current retrieved from the hardware memory module [114] to provide a weighted current. The weighted current from the comparison module [110] is transmitted to the motor controller [116] via a transmission module [112]. TRANSMISSION MODULE
The transmission module [112] employed to transmit one of the predefined current, weighted current to the motor controller [116] to deliver substantially constant air delivery volume per unit time. The transmission module [112] electronically interconnected to the comparison module [110], the detection module [108], the hardware memory module [114], and the motor controller [116], wherein the transmission module [112] transmit any one of a predefined current, and a weighted current to the motor controller [116], to substantially maintain air delivery volume per unit time. HARDWARE MEMORY MODULE
The hardware memory module [114] is adapted transmit a stored pre-defined value to the motor controller [116] by the transmission module [112] upon initialization of a power cycle. The hardware memory module [114] is further adapted to transiently store the weighted current wherein the said weighted current is equal to the value transmitted to the motor controller [116]. Further, the hardware memory module [114] is in communication with the comparison module [110].

OPERATION
FIG. 2 illustrates an exemplary a flow diagram of a method of maintaining air delivery volume per unit time upon initialization of a power on cycle, in accordance with embodiments of the present invention. FIG. 3 illustrates an exemplary flow diagram of a method of maintaining air delivery volume per unit time during operation of a ceiling fan, in accordance with embodiments of the present invention. FIG. 2 and 3 are to be viewed in conjunction with one another, in order to completely understand the concepts of the present disclosure.
The method of maintaining air delivery volume per unit time upon initialization of a power on cycle as shown in Fig.2 initiates at step 202, fetching a default pre-defined current or a weighted current stored in a hardware memory module [114]. At step 204, the default pre-defined or weighed current is transmitted by a transmission module. At step 206, the pre-defined current or weighted current is received by a motor controller. At step 208, motor controller controls/ modulates the fan motor by providing the pre-defined current or the weighted current from the motor controller [116].
The method of maintaining air delivery volume per unit time during operation of a ceiling fan [100] as shown in Fig, 3 initiates at step 302, detecting by a detection module [108] at least an input current value from an output of step-down DC voltage converter of the switch mode power supply [102]. At step 304 and 306, the comparison module [110] compares the detected input current value from the output of step-down DC voltage converter with at least a pre¬defined current from the hardware memory module [114] to provide a weighted current. At step 308, the weighted current is transmitted by a transmission module [112] to a motor controller [116]. At step 310, the weighted current is stored transiently in the hardware memory module [114] as a default value. At step 312, the weighted current is provided to the fan motor by the motor controller [116] to control the speed of the fan to maintain air volume delivery.

Notably, with such arrangement of the ceiling fan [100], the control unit [102] enables to the ceiling fan [100] to maintain a substantially constant air delivery volume per unit time. Further, there is reduction in the time taken for the fan to reach optimum speed as the hardware memory module [114] provides a stored current value to the motor controller [116].
EXAMPLES
During regular use of a ceiling fan, the blades of the fan may be damaged due to wear-and-tear, or due to accidental damage, as a result of which, the blade angle of one or more blades of the ceiling fan may be altered. Such change in blade angle will result in change in air delivery volume as a function of time due to change in the blade resistance to air as it rotates. In conventional ceiling fans, for a particular selected regulator setting, the speed (RPM) of the fan is kept constant, and change in blade angle may also result in change in power requirements of the ceiling fan. As a result, for a particular selected speed, not only the air volume delivery is mismatched, there is also changes in power input.
In an exemplary implement, as seen in Table 1, change in blade angle results in increase or decrease of the air delivery volume per unit time. As the angle of fan blade is increased, there is an increase in air delivery volume per unit time due to increased air resistance the blade encounters when rotating. This is also associated with increased power requirement to maintain the speed of the fan at the desired RPM. Conversely, as the angle of the fan is decreased, there is a decrease in air delivery volume per unit time due to decreased air resistance the blade encounters while rotating. This is also associated with change in power requirement.
Table 1:

1. 2. 3. 4. 5. Blade Angle Power (W) Speed (RPM) Air Delivery (Approx.)

7 21 350 203

7.5 23.6 350 207

8 25.8 350 214

8.5 28 350 219

9 29.5 350 221
In view of the above, there is a need to maintain a constant air delivery volume, which is achieved by the interface circuit as substantially described in the present specification. Table 2 below shows that with changing blade angle, the ceiling fan of the present invention is able to maintain a substantially same air delivery volume by changing the speed (RPM) of the ceiling fan. The power requirement is also controlled within a narrow band as compared to Table 1, resulting in power savings.
Table 2:

1. 2. 3. 4. 5. Blade Angle Power (W) Speed (RPM) Air Delivery (Approx.)

7 25 372 215

7.5 26.1 362 217

8 26.5 350 216

8.5 26.8 336 216

9 26.8 326 214
While the preferred embodiments of the present invention have been described hereinabove, it should be understood that various changes, adaptations, and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims. It will be obvious to a person skilled in the art that the present invention may be embodied in other

specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.
LIST OF REFERENCE NUMERALS
100 – Ceiling Fan
102 – AC/DC SMPS
104 – Step Down DC voltage converter
106– Interface circuit
108 - Detection Module
110 – Comparison Module
112 – Transmission Module
114 – Hardware Memory Module
116 – Motor Controller
118 – Fan Motor

We claim:
1. An interface circuit [106] for maintaining air delivery volume per unit time of
a ceiling fan [100], wherein the interface circuit [106] comprises:
a. a detection module [108] to detect at least an input current from
an output of an AC/DC SMPS (switch mode power supply) [102] of
the ceiling fan [100];
b. a comparison module [110] to compare the input current with at
least a pre-defined current to provide a weighted current; and
c. a transmission module [112] to transmit the weighted current to a
motor controller [116] electrically connected to a fan motor [118]
for maintaining air delivery volume per unit time.
2. The interface circuit [106] as claimed in claim 1, comprising a hardware memory module [114], wherein the hardware memory module [114] is adapted to transiently store the weighted current, said weighted current is equal to the value transmitted to the motor controller [116].
3. The interface circuit [106] as claimed in claim 2, wherein the hardware memory module [114] is adapted to transmit a stored pre-defined current by the transmission module [112] or the weighted current to the motor controller [116] upon initialization of a power on cycle.
4. The interface circuit [106] as claimed in claim 1, wherein said detection
module [108], comparison module [110], and transmission module [112] are
provided in a single unit.
5. The interface circuit [106] as claimed in claim 1, wherein said detection module [108], comparison module [110], and transmission module [112] are individual units interconnected with each other.
6. The interface circuit [106] as claimed in claim 1, wherein the AC/DC SMPS (switch mode power supply) [102] comprises a step-down DC voltage converter and AC/DC converter.

7. A method for maintaining air delivery volume per unit time of a ceiling fan
[100] upon initialization of a power on cycle, said method comprising:
a. fetching at least a stored pre-defined current or a weighted
current stored in a hardware memory module [114]; and
b. transmitting the pre-defined current or the weighted current from
the hardware memory module [114] to a motor controller [116]
electrically connected to a fan motor [118] via transmission
module [112];
wherein said hardware memory module [114] is comprised in an interface circuit [106] as claimed in claim 1.
8. The method as claimed in claim 7, wherein the pre-defined current or a weighted current is a default value transiently stored in the hardware memory module [114].
9. The method as claimed in claim 7, wherein said detection module [108], comparison module [110], and transmission module [112] are provided in a single unit.
10. The method as claimed in claim 7, wherein said detection module [108], comparison module [110], and transmission module [112] are individual units interconnected with each other.
11. A method for maintaining air delivery volume per unit time during operation of a ceiling fan [100], said method comprising:
a. detecting by a detection module [108] at least an input current
from an output of an AC/DC SMPS (switch mode power supply)
[102] of the ceiling fan [100];
b. comparing the input current with at least a pre-defined current in
a comparison module [110] to provide a weighted current; and
c. transmitting by a transmission module [112] the weighted current
to a motor controller [116] electrically connected to a fan motor
[118],

wherein the speed of the ceiling fan [100] is varied to maintain air delivery volume per unit time; and the detection module [108], comparison module [110], and the transmitting module are comprised in an interface circuit [106] as claimed in claim 1.
12. The method as claimed in claim 11, wherein said weighted current is transiently stored in a memory hardware module [114] comprised in the interface circuit [106] as claimed in claim 1.
13. The method as claimed in claim 11-12, wherein said detection module [108], comparison module [110], and transmission module [112] are provided in a single unit.
14. The method as claimed in claim 11-12, wherein said detection module [108], comparison module [110], and transmission module [112] are individual units interconnected with each other.