DESC:FIELD OF THE INVENTION:

The present invention generally relates to mosquito repellent liquid vaporizer. More particularly, it relates to an electronic control solution for mosquito repellent liquid vaporizer using PTC as a cheapest power supply circuit to create a safety environment.

BACKGROUND OF THE INVENTION:

Liquid repellents are widely used to keep mosquitoes away. The liquidator mosquito repellent has a graphite rod in the middle surrounded by a heater and the bottle is filled with the repellent. The repellent chemical vaporises and disables the sensors (nervous system) of the mosquitoes. The fumes produced by the repellent blocks the chemo sensors of mosquitoes so that they cannot identify human beings.

Conventional liquid vaporizers or liquidators use different type of heaters such as pure resistor/resistive method, PTC/NTC (Positive/Negative Temperature Coefficient) Thermistor and induction coil heaters. The liquid vaporizers use either a single heater or two heaters to vaporize the chemicals. In the single heater liquid vaporizers, as long as the unit is in power on mode, the heater will produce constant heat and keep vaporising. There is no time control for on/off and no control for the heater.

When two heaters are used, these can be controlled by either manual, bi metal sensor or electronic unit. It produces different temperatures by using the above control at different times as per the requirement. Also, the temperature changes the quantity of vaporizer. There are two modes available called as active mode and normal mode. In the active mode, two heaters are on, and the temperature is above 150 degrees. Under these conditions, more vapour is produced. The active mode duration can be controlled by manual, bi metal or electronic method. After active session, the unit will switch over to one heater mode which is called the normal mode. In this mode, the temperature will be 30-40 degrees lesser than the active mode temperature. So, vapour produced is also lesser. The concept of active and normal mode was used to keep away the mosquitoes immediately within few minutes of switching on and then once the mosquitoes are away, the normal mode maintains it. This saves the chemical and cost too.

The manual heater control method uses a mechanical slide switch which is used by consumer to select active mode or normal mode. The problem in this control is, if the user forgets to switch over from active mode to normal mode, it will lead to more chemical usage and also hazardous to health. So, it is preferable to have an automatic control using a bimetal sensor. In the automatic control method, initially the machine switches on both the heaters and once a desired temperature is reached, then the Bi metal sensor senses the heat and delinks one heater. The problem in this is that the manufacturer cannot decide on the active mode duration. Whenever there is need for more time or control of time of active mode, this will not support and hence the purpose of having the automatic controls to change the modes will not be served.

The above problems faced in the manual and Bi-metal sensor methods can be solved by the electronic control method in which an electronic circuit is used to have all control by the manufacturer or user. The active mode time can be changed by the manufacturer. A longer period can be set by the manufacturer. In case, the consumer wants more time of active mode, then the unit can be restarted again to have more active mode. If necessary, the electronic control can be designed to make user be able to adjust the active mode session. The electronic control can be achieved by 555 timer, op amp, micro controller and ASIC.

The electronic circuits normally operate with low voltage in the range of 3V-24VDC whereas the Indian power outlets are 230VAC. So, to bring down low DC voltage from high AC voltage, a power supply circuit is required. There are different types of power supply techniques such as conventional power supply using a step-down transformer, SMPS, capacitance dropping method and resistor dropping method to operate electronic circuit with low voltage of about 3V-24VDC. The use of conventional power supply and SMPS are more costly and bulky in nature. Though the capacitance dropping method and resistor dropping method are cost effective, it cannot withstand repeated surge which may lead to an explosion on fire.

Also in existing circuits, the arrangement of electronic components in mosquito repellent liquid vaporizers involves the connection of PTC and load in parallel with main supply 230V and also with indication (LED) circuit, which results in less protection and does not provide safety on high voltage surge. Further, the PTC is driven by full-wave rectifier, which also increases the cost. Therefore, the skill of the designer is important to select the right components to overcome these problems.

There are many mosquito repellent liquid vaporizers known in the existing art. For example, prior art CN202436006, CN201805843, CN2216342, CN2292388, US7201916 and US6792199 deal with insect repellent liquid vaporizers that comprise of a separate power supply circuit and PTC as heater/output load.

Hence, there is a need for a simple, safe and cost-effective solution without using separate power supply circuit.

Thus, in order to overcome the above mentioned problems and to minimize the use of complex circuits in the existing art, the present invention provides a simple, low cost, less space and fewer components to achieve safe electronic control solution for mosquito repellent liquid vaporizer.

SUMMARY OF THE INVENTION:

An objective of the present invention is to provide an electronic control solution for mosquito repellent liquid vaporizer which uses same PTC as heating load as well as to produce low voltage to drive an electronic circuit.

In order to achieve the above objective, the present invention discloses an electronic control system for mosquito repellent vaporizer. The electronic control system comprises an input power, an electronic circuit and an output load. The input power used here is 230VAC and it uses one or more PTC (Positive Temperature coefficient) heaters as an output load and also as an input to drive the electronic circuit without using separate power supply circuit.

According to the present invention, the PTC is not only working as a load but also acts as a barricade to low voltage circuits. It also withstands incidental high input voltage in the order of 500VAC and repeated surge of about 2KV. In addition, PTC changes its resistance value from low to high which simultaneously changes the current through Zener diode from high to low. So, it increases reliability rather than the burdens of Zener diode.

In accordance with the present invention, PTC is connected with a half wave rectifier that used for both power supply as well as to get sufficient heat from the PTC heater.

Thus, the electronic control solution of the present invention uses simple, less cost, less space and less components. It withstands 200% input voltage and repeated surge of 2KV. Also, there is no heat generated and hence provides highest safety in terms of explosion.

These objectives and advantages of the invention will become more evident from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The objective of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

FIG. 1A represents a power supply circuit using PTC according to the present invention;

FIG. 1B represents the electronic circuit used according to one embodiment of the present invention;

FIG. 2 represents the arrangement of PTC heater with half wave rectifier and indication circuit according to another embodiment of the present invention when single heater is used;

FIG. 3 represents the use of half wave rectifier to drive PTC according to the present invention;

FIGS. 4A and 4B represent a bottom view of a power supply circuit using PTC according to the present invention; and

FIGS. 5A and 5B represent a top view of a power supply circuit using PTC according to the present invention.

REFERENCE NUMERALS:

Electronic control system (10)
Power supply unit (12)
PTC (Positive Temperature coefficient) heaters (14)
PTC heaters 1 (14A)
PTC heaters 2 (14B)
Electronic circuit or control unit (16)
Input supply line (18)
Load control line (20)
Indication unit (LED) (22)
Half wave rectifier (24)

DETAILED DESCRIPTION OF THE INVENTION:

The present invention provides an electronic control solution for insecticidal liquid vaporizer, i.e. a mosquito repellent liquid vaporizer comprises a cheapest power supply circuit using positive temperature coefficient (herein referred to as PTC) resistor.

A typical electronic circuit consists of an input power, independent power supply circuit, control circuit and output load. The electronic circuits normally operate with low voltage in the range of 3V-24VDC wherein the input power is 230VAC. So, the power supply circuit is required to bring down low DC voltage from high AC voltage. Also typical electronic circuit uses a full wave rectifier circuit for both power supply circuit and to PTC.

Normally mosquito repellent liquid vaporizers use PTC as a heater to produce required heat to evaporate their chemicals and hence, PTC is used as output load. When PTC is at an ambient temperature, its resistance value is less which is in order of 600 to 900 ohms. When PTC is connected to 230VAC, it generates heat and temperature raises which in turn raises the PTC resistance. The maximum resistance value of PTC of about 4000 ohms is reached at desired temperature. Thus, the PTC regulates the desired heat by changing the resistance value. This physical phenomenon of PTC is used in the present invention.

According to the present invention, the electronic control system (10) of mosquito repellent vaporizer comprises of input power / input supply line (18), an electronic circuit / control unit (16) and an output load (14). The input power is 230VAC and the output load is PTC heater (14). The PTC heater (14) is connected with a half wave rectifier D5 (24) at one end and connected with the electronic circuit (16) through load control line (20) at the other end. In the present invention, the PTC (14) is used as heating load as well as used to produce low voltage to drive the electronic circuit (16). The power supply circuit (12) using PTC (14) is represented in FIG. 1A. This eliminates the need of separate power supply circuit such as SMPS or capacitance voltage dropping or resistor voltage dropping.

In the present invention, the PTC heater (14) itself works as a voltage dropping apart from producing the heat. Since PTC (14) is rugged, it has been working in an accidental high input voltage of about 500VAC and also withstands repeated surge of 2KV. Therefore, safety for low voltage electronic circuit (16) is automatically achieved without using extra components. Also, PTC (14) changes its resistance value from low to high, which in turn varies the flow of current through Zener diode Z1 from high to low. So, load on Zener diode Z1 decreases with increase in its reliability.

In one embodiment of the present invention, two PTC heaters (14A and 14B) of different temperatures are used and the electronic circuit (16) is used to control the PTC heaters (14A and 14B) independently. FIG. 1B shows the electronic circuit (16) setup used in this embodiment, in which, the PTC heater (14B) is connected with the half wave rectifier D1 (24) through the Zener diode Z1 and the Fuse F1.

In another embodiment of the present invention, an indication circuit (22) is used to represent the ON / OFF state of the PTC (14) as shown in FIG. 2. In FIG. 2, the indication circuit (22) is connected with the half wave rectifier D2 (24) and the PTC heater/ load (14) is connected in series with main supply 230AC and indication (LED) circuit (22). Thus, the series connection of components increases the protection and saves money. Also, this connection provides safety on high voltage surge.

By referring to FIG. 3, it represents the connection of PTC (14) with the half wave rectifier D2 (24) which drives the PTC (14) in both the embodiments. The use of half wave rectifier D2 (24) provides the same heating as the conventional method of driving PTC (14) by full wave rectifier. The implementation of half wave rectifier (24) results in simple circuit design and also reduces the circuit cost and time.

FIGS. 4A and 4B illustrate the bottom view of the power supply circuit using PTC within the electronic control system (10) and FIGS. 5A and 5B illustrate the top view of the power supply circuit using PTC within the electronic control system (10), where the size of Printed Circuit Board (PCB) assembly, look of the PCB assembly and arrangements of electronic components may differ with respect to outer case.

Thus, the present invention provides a low voltage power supply circuit using PTC which is simple, safe, cost effective, less space, less components and withstands 200% input voltage and repeated surge of 2KV, for mosquito repellent liquid vaporizers. The electronic control system described in the present invention is applicable to all types of liquid vaporizer.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope of the invention as claimed.
,CLAIMS:We Claim:

1. An electronic control system (10), comprising:
a. an input power (18);
b. an electronic circuit (16);
c. one or more positive temperature coefficient resistor (PTC) (14) as output load, wherein said PTC (14) is also designed to supply low voltage to said electronic circuit (16); and
d. a half wave rectifier (24).

2. The electronic control system as claimed in claim 01, wherein said electronic control system (10) is applicable to all types of liquid vaporizer including but not limiting to insecticidal liquid vaporizers.

3. The electronic control system as claimed in claim 02, wherein said insecticidal liquid vaporizer is a mosquito repellent liquid vaporizer.

4. The electronic control system as claimed in claim 01, wherein said PTC (14) is driven by said half wave rectifier (24).

5. The electronic control system as claimed in claim 01, wherein said PTC (14) is connected in series with said input power (18) and indication (LED) circuit (22).

6. The electronic control system as claimed in claim 01, wherein said PTC (14) changes the flow of current from high to low through the Zener diode by changing its resistance value from low to high.

7. A mosquito repellant liquid vaporizer, comprising:
an electronic control system (10), comprising:
a. an input power (18);
b. an electronic circuit (16);
c. one or more positive temperature coefficient resistor (PTC) (14) as output load, wherein said PTC (14) is also designed to supply low voltage to said electronic circuit (16); and
d. a half wave rectifier (24).