Description:A next generation electricity generating backpack is designed that is very much lighter in weight, has multiple electricity generating mechanisms used in the straps of the backpack. Piezoelectric material is used in this electricity generating mechanism for electricity generation. Piezoelectric materials are the materials which generate electricity when a pressure force is applied on these materials. This backpack works on the concept of piezoelectric effect. Piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. Piezoelectric materials are very much sensitive in voltage generation through very small deflection.
Main element that is used to apply force to the piezoelectric material is a circular cylinder of solid structure. This solid cylinder is used to apply the force on the piezoelectric ceramic discs. The reaction force obtained through the application of applied force by the circular cylinder is used to transfer the reaction force to the piezoelectric crystal that is attached with the circular cylinder i.e. force application member.
Piezoelectric crystals employed in all the electricity generating mechanisms are designed to be in the form of simply supported beam .Force is applied at the center of the beam by force application member and central deflection of the beam is obtained. Simply supported beam structure is used because it gives maximum deflection if the force is applied at the center.
A special structure is designed for piezoelectric ceramic disc to act as simply supported beam. Basic structure of both the circular and rectangular generators are same but the external structure are designed to make it light weight, comfortable and compatible to the user. Basically Polly lactic acid (PLA) is used to design the structure but it can be changed according to strength requirement. Poly lactic acid is basically a general purpose plastic that is very much ecofriendly and biodegradable too.
All the piezoelectric ceramic discs are attached in parallel combination so that their voltage generation can be added together. In the same way all the four electricity generating components are attached to an electronic circuit and battery is charged through the voltage generated.
When user of backpack walks with the backpack having straps on the shoulders, he creates tension in the straps alternatively during movement. This tension force is converted to the compression force through the design of components. The compressive force generated inside the component is used to apply the compression force to the piezoelectric material. In this way voltage generated and this is stored in the battery. Voltage is generated anytime when the straps of the backpack feels tension. The voltage generation also depends upon the way of movement. So in case of running or moving faster this will generate more electricity. The electricity generated and stored by the backpack may be used to charge batteries and to power a number of devices that may be carried by the backpack.
These and other characteristics features of the invention will be apparent to those skilled in the art based on the following description of the invention.

Claims:1. An energy harvesting back pack comprising of shoulder straps that are connected with the energy harvesting components. Rectangular energy harvesting components are attached with upper part of the straps and circular components are attached with the lower part of the straps. Piezoelectric ceramic disc are used to generate the electricity. These discs are arranged in the form of simply supported beams in the structure. All the wires and electronic circuit is internal to the backpack. Battery is used to store the voltage.
2. An electricity generating backpack as in claim 1, wherein said electricity generating mechanism comprises some piezoelectric discs. These discs are made of some piezoelectric discs. These discs are made of some piezoelectric materials. Different types of piezoelectric materials have some different voltage generation. So all these different types of piezoelectric materials can be used in place of the material used in the present invention. The battery charging backpack will vary with respect to different types of materials.
3. An electricity generating backpack as in claim 1 further compromising of a force application member. This is used to apply force to the discs and used between two discs. The diameter and shape of the force application member can be varied according to the requirements. The diameter of the force application member also varies according to the thickness of different types of materials.
4. An electricity generating backpack as in claim 1 consists of energy harvesting components. In the present invention, Poly lactic Acid (PLA) is used to design these components but this material can be changed to any other material according to strength requirements for the backpack. These components should be designed with respect to load carrying by the backpack.
5. Energy harvesting components used in the straps can be taken internal to the backpack. Energy harvesting components requires only the tension for the mechanism. Same tension can be given to the mechanism by attaching these components internal to the backpack. S energy harvesting components can also be used internal to the backpack.
6. An electricity generating backpack as in claim 1consists of electronic circuits. This electronic circuit can be changed or modified according to the voltage generation. Various electronic components like Diode, Capacitors are used to store the charge in the battery. The other entire electronic component can be used in making the electronic circuit.
7. The design of energy harvesting components that are used to support the piezoelectric ceramic disc in form of simply supported beam can be changed according to requirements.
8. Piezoelectric ceramic discs are designed in the form of simply supported beams but it can be changed to cantilever beams or overhanging beams but specific design will be required. Simply supported beam structure is used to get the large deflections. But same deflection can also be achieved through some other modified designs.
9. An energy harvesting backpack consists of a Li ION battery that is used to store the voltage but this battery can be changed to other according to voltage generated and some specific requirements.
10. The mechanism of energy harvesting backpack can be used in any bag i.e. hand bags, side bags, carry bags etc. This mechanism can be modified to use it for other type of bags also.