Patent Application
20090184106
The present invention generally relates to heating devices, and more particularly to a flexible planar heating device whose heat producing members connect to a power source via a number of low-resistance members.
In conventional planar heating devices, conducting wires or rigid circuit boards are arranged across a planar heat-producing member so as to create a large warm area. The common drawbacks of these heating devices are that it takes a considerable amount of time for the heat-producing member to heat up, the heat is not evenly distributed, and the heating devices usually cannot be folded or bended.
Flexible planar heating devices using various types of fabrics as heat-producing members are disclosed, for example, in R.O.C. Taiwan Patent Nos. M257591 and M294805. These devices have their power cables connected to the heat-producing members via point contacts such as those by soldering or riveting. A high temperature is usually developed at these contact points, which would cause some protective covers to the heating device to catch fire and, therefore, presents a potential hazard to the user. Additionally, these protective covers could be easily peeled off after a period of usage and the heating device is therefore not properly insulated.
U.S. Pat. Nos. 7,115,844, 4,149,066, and 3,359,524 also teach planar heating devices yet with similar drawbacks described above. For example, the planar heating device of U.S. Pat. No. 7,115,844 has point contacts; and the heating devices of U.S. Pat. Nos. 4,149,066 and 3,359,524 would take a rather long time to heat up, suffer uneven heat distribution, and result in broken conducting wires after a period of usage.
The foregoing teachings further suffer additional drawbacks such as that they all consume a considerable amount of electricity, which is not quite environmentally friendly from today's standard, and that they are rather rigid to fit on various objects, and that their protective covers could easily be peeled off.
Accordingly, a novel flexible planar heating device is provided herein that avoids the use of point contacts, reduces electricity consumption without sacrificing heating time, and achieves a substantially uniform heating.
To achieve these objectives, the heating device according to the present invention utilizes a number of linear, low-resistance conducting members sandwiched between two flexible heat-producing members. The linear conducting members function as intermediate media to the wires of a power cable. The large contact area between the linear conducting members and the heat-producing members prevents the development of high temperature at a few points. The linear conducting members, on the other hand, help distributing the electrical current to the heat-producing member so as to achieve shorter heating time and more uniform distribution of heat. In addition, a number of through openings distributed across the heat-producing members help lowering the electricity consumption with no noticeable effect to the user.
The heating device could be submerged in insulating ink and then thermally cured to form an insulating ink layer around the heating device to provide the required insulation. Alternatively, an insulating member could be coated on the heating device.
The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts.
Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.
The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims.
As shown in
The first conducting member 10 is made of an electrically conducting rubber having a high resistance. The first conducting member 10 can have an appropriate planar shape and is not limited to the rectangular shape as illustrated. Preferably, the first conducting member 10 is made of silicone rubber conductor so that the first conducting member 10 can be flexibly pressed into a planar shape and cam be flatly arranged on a surface of an object. When electricity is introduced through the first conducting member 10, heat is produced from its high resistance. The openings 11 are provided to reduce the amount of electricity consumed. The openings 11 can also have appropriate shapes and sizes, and can be arranged across the first conducting member 10 in various ways. For example, as; shown in
The second conducting member 20 can be made of a rigid or flexible conducting material but with a resistance substantially smaller than that of the first conducting member 10. Preferably, the second conducting members 20 have resistances below one ohm. The second conducting members 20 can have a planar shape, a strip-like shape, or a wire-like shape. They can be integrally formed and embedded in the first conducting members 10 by the application of heat and pressure, or they can be flatly attached to the first conducting members 10. If the second conducting members 20 are made of a flexible material, it can be flexibly laid on an object's surface along with the first conducting members 10.
Each conducting wire 30 has at least one of its ends connected to a second conducting member 20. Two of the conducting wires 30 have the other ends connected to the positive and negative terminals of an external DC or AC power supply (not shown) so as to introduce electricity into the first conducting member 10 via the second conducting members 20. The voltage of the power supply could range from 0.1V to 500V. The temperature of the heating device could range from 1° C. to 230° C. relative to the environment.
The insulating members 40 can be made of a rigid or flexible insulating material such as non-woven fabric, silicon, and plastic film. The first conducting members 10, the second conducting members 20, and the conducting wires 30 interconnecting the second conducting members 20 are flatly sealed between the two insulating members 40. The insulating member 40 is, on one hand, to enhance the robustness of the heating device and, on the other hand, to prevent electrical short circuit or leakage of the first and second conducting members 10 and 20 if they are in direct contact with the object to be heated. For each opening 11 of the first conducting members 10, there are compatible and corresponding openings 41 on the insulating members 40.
For the heating device as described, using the second conducting members 20 as intermediate media between the conducting wires 30 and the first conducting members 10, due to the low resistance and large contact area of the second conducting members 20, leads to an even distribution of electrical current and a shorter heating time, and also prevents the produced heat from concentrating at a few points.
Four embodiments (namely, a, b, c, and d) of the present invention are shown in
Similarly, as shown in
As illustrated in
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As illustrated in
While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.
