FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit
APPLICANTS
Crompton Greaves Limited, Co House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
Inventors
Siddiquee Qutbuddin and Guruguntla Nagarjuna, both of Crompton Greaves Limited, IPR Cell & Technology Information Centre (TIC), C G Global R&D, Kanjurmarg (East), Mumbai 400 042, Maharashtra, India, both Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF THE INVENTION
This invention relates to an oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit.
BACKGROUND OF THE INVENTION
During operation of an oscillatory table fan or pedestal fan, the fan oscillates about a vertical axis and distributes the cooling air being swept and blown by the fan and makes the cooling air available over a large area. Oscillatory' motion of the fan is usually within about 180° and is given by a swing motor. During the oscillatory motion, the fan rotates at a constant speed selected on the speed regulator or remote control by manually operating the speed regulator or remote control by hand. Manual selection of speed control is inconvenient and cumbersome to carry out and the fan is not, therefore, user friendly. Besides this, the users of a fan most often position themselves in front of the fan in a staggered manner. Some of the users may be close to the fan while others may be away from the fan. Users also often do not sit uniformly in rows in front of the fan. As a result of all this, some places or seats in the various rows will remain vacant. Since the fan rotates at the selected constant speed during the oscillatory motion of the fan, cooling air is not available to all the users in a proportionate manner or in equal amounts. Users away from the fan receive less cooling air as compared to those close to the fan. Therefore, comfort level offered by the fan to the various users is not in a proportionate manner. There is also wastage of energy. Further the fan completes its full angle of oscillation irrespective of whether there are users sitting along the entire path of oscillation of the fan. Wherever there are no users along the path of oscillation of the fan, cooling air being swept and blown by the fan is not made use of. This results in further wastage of energy as no useful

purpose is served. US 2005/0276695A1 describes an electric fan with a sensing arrangement which changes the speed of the fan responsive to change in temperature or body odour. The sensing arrangement includes temperature or smell sensor, a control chip, a light control unit, a light sensor and a power control unit. Only automatic speed control of the fan is achieved by the sensing arrangement.
OBJECTS OF THE INVENTION
An object of the invention is to provide an oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit which increases or reduces the fan speed responsive to position of users with respect to the fan and which limits the angle of oscillation of the fan depending upon the position of users so as to increase comfort level to the users and reduce wastage of energy.
Another object of the invention is to provide an oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit, which is user friendly and is simple in construction.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided an oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit comprising a microprocessor connected to an object sensor and to a first logic gate, the first logic gate being connected to the object sensor and to a distance sensor, the object sensor and distance sensor being mounted on the fan support structure facing the users, a digital to analog converter connected to the microprocessor and to a voltage comparator, the voltage comparator being connected to a RAMP generator and to a

TRIAC, the TRIAC being connected to the fan motor and to an AC power supply, the microprocessor being further connected to the swing motor of the fan through a second logic gate.
The following is a detailed description of the invention with reference to the accompanying drawings, in which the sole Fig 1 is a block diagram of the automatic speed and oscillation controlling circuit according to an embodiment of the invention. The automatic speed and oscillation controlling circuit 1 as illustrated in Fig 1 of the accompanying drawings comprises a microprocessor 2 connected to an object sensor 3 and a first logic gate 4. The first logic gate 4 is also connected to the object sensor and a distance sensor 5. Both the object sensor and distance sensor are mounted on the support structure (not shown) of AC driven table fan or pedestal fan (not shown) facing the users. 6 is a digital to analog converter connected to the microprocessor and to a voltage comparator 7 which comprises various voltage references corresponding to various speeds of the fan. Voltage comparator is connected to a RAMP generator 8 and to a TRIAC 9. The TRIAC is connected to the fan motor 10 and to an AC power supply 11. The microprocessor is also connected to the swing motor 12 of the fan through a second logic gate 13. The object sensor is, for instance, passive infrared based sensor and the distance sensor is for instance, laser or ultrasonic based sensor. The presence of users in front of the fan will be sensed by the microprocessor based on input from the object sensor. The first logic gate 4 senses the presence of users from the object sensor and also the distance of the users with respect to the fan through the distance sensor and inputs a corresponding signal to the microprocessor. Based on the input from the first logic gate 4 regarding the presence of the users and also the position of the users with respect to the fan, the

microprocessor outputs a digital signal to the digital to analog converter 6 proportional to the speed at which the fan should be rotated. The digital to analog converter converts the digital signal to a corresponding voltage and feeds the voltage signal to the voltage comparator. The DC voltage is used as a reference input of the comparator whereas the Ramp wave form generated by the Ramp generator and synchronized to the AC power supply wave form is used as the other input to the comparator. The resultant signal from the comparator which is a phase angle controlled trigger signal drives the TRIAC. The TRIAC conducts and turns on the fan motor for the corresponding duration of the AC power supply wave form and causes the fan to rotate for the corresponding duration at the rated speed selected by the microprocessor. Depending upon the presence and position of the users with respect to the fan, the fan speed will be increased or reduced so as to give the required amount of cooling air to the users and satisfy the cooling requirement of the users. Since the fan rotation is automatically controlled responsive to requirement in terms of presence and position of users wastage of energy is eliminated. Simultaneously the microprocessor controls the oscillation of the swing motor through the second logic gate depending upon the presence and location of the users with respect to the fan and prevents oscillation of the fan along the path where there are no users. This helps to further save energy and operate the fan in an energy efficient manner. Since the operation of the fan is automatic without having to select fan speed on a speed regulator or remote control it is easy and convenient to operate the fan and the fan is user friendly.
The above embodiment is by way of example of the invention and should not be construed and understood to be limiting the scope of the invention. The fan can be

wall mounted also. In the case of a DC driven fan, a Bipolar transistor or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) can be used in the place of TRIAC. Embodiments comprising such variations of the invention are obvious to those skilled in the art and are to be construed and understood to be within the scope of the invention.

We claim :
1) An oscillatory table fan or pedestal fan with an automatic speed and oscillation controlling circuit comprising a microprocessor connected to an object sensor and to a first logic gate, the first logic gate being connected to the object sensor and to a distance sensor, the object sensor and distance sensor being mounted on the fan support structure facing the users, a digital to analog converter connected to the microprocessor and to a voltage comparator, the voltage comparator being connected to a RAMP generator and to a TRIC, the TRIAC being connected to the fan motor and to an AC power supply, the microprocessor being further connected to the swing motor of the fan through a second logic gate.
2) The automatic speed and oscillation controlling circuit as claimed in claim 1, wherein the object sensor comprises a passive infrared based sensor and the distance sensor comprises a laser or ultrasonic based sensor.
Dated this 19th day of March 2009