THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

TRANSACTION RETENTION DURING POWER FAILURE WITH CAPACITOR MODULE IN FUEL DISPENSER.
numbered as dated
A) FIELD OF TECHNOLOGY:
1. The present invention relates generally to electronics and specifically to the field of memory retention of a transaction module and more specifically to the use of transaction retention in fuel dispenser during power failure. The invention is presented for fuel dispenser but the application not only Hmited to dispensing but also to any dispensing unit or continuous counting unit where the last transaction needs retention during power failure and thereof.
B) DESCRIPTION OF PRIOR ART:
2. This invention relates to a method and apparams for retaining the last transaction in fuel dispenser using power storage capability during a power failure scenario in petrol pumps and other fields wherein there is continuous count of transaction detail, such as in telephone billing meter etc.,
3. In the modern world gasoline or fiiel are supplied to the customer at various stations or bunks by major oil companies across the world. At each station, a centralized site controller may control all of the communications with the plurality of gasoline dispensers. The dispensers may also include magnetic card readers for reading credit and debit cards for the purpose of collecting money from the customers. The ftiel dispenser may also include devices such as bar code readers, cash acceptors, and change machines.

4. Fuel dispensers most popularly known as fuel pumps, at fuel stations dispense fuel from underground tanks to customer automobiles. Apart from dispensing the fiiel dispensers also calculate and measure the quantity of fuel dispensed so that customers may be billed for the amount of ftael that they receive. The quantity of liquid fiiel that is dispensed is measured using a fuel meter. Modern service stations often provide up to four different products or grades of fuel on each of two sides of a fuel dispenser. Each fuel dispenser therefore includes up to eight fuel meters, one for each grade of fuel on each side of the dispenser.
5. The type of fuel meter commonly used in fuel dispensers for the last fifty years is a positive displacement piston-type meter. This type of meter has traditionally been used due to its ability to measure liquid flow at both low rates of flow and at high rates of flow. Each fuel bunk may have one or more dispenser unit which fetches fuel from a stored location (general under the ground). Each dispenser unit may have one or more pumps and nozzles to dispense fuel fetched from the main storage space.
6. When there is a power failure while fuel dispensing is going on in one or more
dispensing unit, the transaction details may get erased or vanish from the display
unit. Though the dispenser stops pumping out fuel, the bill for the pumped out fuel
now becomes unaccounted for and thereof. For this purpose the petrol bunks may
have been provided with expensive battery back up or uninterrupted power supply
units called UPS or may have generators for continuous supply of electricity. This
leads to inconvenience of spending lot of money on having such back up and most
fuel bunks may not have it. It is primary intention of this invention is to address one
such issue with fuel bunks where there is often power failure is encountered.

C) OBJECT OF THE INVENTION:
7. It is the primary object of the invention to invent an electronic hardware to retain power for the display module of a fuel dispenser.
8. It is another object of the invention to invent a method of providing power back up for the display unit for at least twenty minutes.
9. It is another object of the invention to invent a low cost electronic module without compromising on the requirements to retain the power for the display unit of a fuel dispenser.
10. It is another object of the invention to invent an electronic hardware, which does not alter the voltage level of the input power while in operation by drawing negligible power that should not affect the remaining operation of the dispenser unit.
D) PROPOSED SOLUTION:
11. We propose a novel design in the field of fuel dispenser display unit. The novelty of the design is in having back up for the display unit. Even though battery back up may be provided for the display unit it adds up the following inconvenience
• The battery will add extra weight to the dispenser unit
• The user may forget to change the battery as and when it is totally discharged
• Continual money spent on battery

12. Our current novel design of back up avoids all these discomfort and annoyance and still serving the purpose. The block diagram of the electronic hardware for power retention in display unit is given below.
E) Description of the Design
13. The novel design of the power back up unit consists of a 5 volt dc source [1] which is active while the main power supply is ON, a forward diode [2] to prevent discharging of the capacitor to the dc source[l], a limiting resistor [3] which primary controls the capacitor charging current from the main power supply when the power is ON, a discharge diode [4] which prevents capacitor-^from discharging through the limiting resistor [3], the capacitor [6] of lF/5.5 volt whose primary job is to discharge the power stored during power failure to the display controller and liquid crystal display (LCD) module [5], a 7 volt dc power supply [7] for the back lit light emitting diodes (LEDs) and a backlit LEDs [8] placed behind the LCD module to make the background of the display unit bright and to make the characters more visible.
F) Operational Details of the Hardware
14. Diagrammatically described unit of the current invention wiU be elaborated in detail about the operation of the unit. The high value capacitor [6] requires high inrush charging current that has to be controlled by the forward diode [2] while charging of the capacitor under normal circumstances when the main power supply is ON. This also prevents and blocks the capacitor charge being discharged back to the main power supply circuit [1] on power failure conditions. Limiting resistor [3] is provided to limit the inrush charging current. To avoid capacitor [6] discharging to the load

(display circuit here) [5] through this limiting resistor [3] discharge diode [4] is connected.
G) The best method of perfotming the invention:
15. To summarize, the scheme presented here is implemented by designing the power
back up module along with the display unit and tested in a fuel-dispensing unit. The
capability of the transaction retention module is shown below.
16. Under normal operating conditions of the display module [5] the capacitor [6] can
discharge 2 volts and the display module would draw a current of 0.001 Amperes. A
simple graphical representation below gives the time versus current drawn for the
module and it is evident that the capacitor can support the display module without
any input current for more than 30 minutes.

WE CLAIM:
The design and use of transaction retention module for fuel dispenser unit with the capability of supplying power to the display module more than 30 minutes is claimed here.
What is claimed:
1. A design and use of transaction retention module for fuel dispensing unit in
plurality constituting
a capacitor for charging and discharging current;
two diodes to prevent reverse power discharge;
a display unit for the transaction display;
a back lit for displaying the units and characters more brighter;
2. The method of claim 1, wherein said step of charging comprising the capacitor
capable of drawing minimum current while the main power is ON is claimed
here.
3. The method of claim 1, wherein the said step of discharging comprising the capacitor capable of discharging power to the display unit more than 30 minutes under normal working conditions is claimed.
4. The method of claim 1, wherein the said step of charging and discharging of the capacitor replacing the costly affair of using batter back for the purpose of power supply to the display unit is claimed here.

5. The method of claim 1, wherein the said step of charging and discharging
preventing the user from time to time taking pains to replace the power back up
utiit is claimed.
6. The method of claim 1, where in the said step of charging and discharging
allowing enough time to store the retained value in a permanent memory for later
use is claimed.