Cellular telephone shield for the reduction of electromagnetic radiation exposure

Abstract

A radiation shield comprises a substrate polymer layer, a conductive layer having an aperture providing access to a front face of a cellular telephone, adjacent the substrate polymer layer, and an adhesion surface adjacent the conductive layer and the front face. A radiation shield comprising a first substrate polymer layer, a conductive layer having an aperture providing access to a touch-sensitive screen of the front face, adjacent the first substrate polymer layer, a second substrate polymer layer adjacent the conductive layer, and an adhesion surface adjacent the conductive layer and the front face. At least one opening provides access to the front face.

Claims

1. A radiation shield for attachment to a cellular telephone, the cellular telephone having a front face and a touch-sensitive screen, comprising: a first substrate polymer layer; a conductive layer, adjacent the first substrate polymer layer; a second substrate polymer layer, adjacent the conductive layer; an adhesion surface, adjacent the second substrate polymer layer and the front face; the conductive layer having an aperture that provides access to the touch-sensitive screen; whereby the radiation shield attenuates electromagnetic radiation.

2. The radiation shield of claim 1, wherein the cellular telephone has a set of controls and the radiation shield has at least one opening providing access to the set of controls.

3. The radiation shield of claim 1, wherein the first substrate polymer layer has a thickness range of approximately 0.1 mm to approximately 0.7 mm.

4. The radiation shield of claim 1, wherein the first substrate polymer layer is a material selected from the group of polyester, polyethylene terephthalate, glass, and polycarbonate.

5. The radiation shield of claim 1, wherein the second substrate polymer layer has a thickness range of approximately 0.1 mm to approximately 0.7 mm.

6. The radiation shield of claim 1, wherein the second substrate polymer layer is a material selected from the group of polyester, polyethylene terephthalate, glass, and polycarbonate.

7. The radiation shield of claim 1, wherein the conductive layer has a sheet resistance range of about 10 ohms per square to about 15 ohms per square.

8. The radiation shield of claim 1, wherein the conductive layer has a thickness range of approximately 0.03 mm to approximately 0.06 mm.

9. The radiation shield of claim 1, wherein the conductive layer is made of a material selected from the group of indium tin oxide, silver, gold, graphene, carbon nanotubes, polyacetylene, polyphenylenen vinylene, polythophene, polyphylene sulfide, polyaniline nanofibers, and carbon nanofibers.

10. The radiation shield of claim 1, wherein the adhesion surface further comprises an adhesive layer.

11. The radiation shield of claim 1, wherein the adhesive layer has a thickness range of approximately 0.035 mm to approximately 0.065 mm.

12. The radiation shield of claim 1, wherein the aperture is a semi-transparent region having at least 84% transparency.

13. The radiation shield of claim 1, further comprising: the conductive layer juxtaposed between the first substrate polymer layer and the second substrate polymer; the second substrate polymer layer juxtaposed between the conductive layer and the adhesion surface; the conductive layer formed as a metallic coating; a first opening that is sized to approximately match a speaker of the cellular telephone; a second opening that is sized to approximately match a camera of the cellular telephone; a third opening that is sized to approximately match a button of the cellular telephone; the aperture having a set of dimensions that are approximately equal to a set of dimensions of the touch-sensitive screen; the aperture being an area of the radiation shield where the conductive layer is not present; the electromagnetic radiation that is attenuated is in one of the 800 MHz band and the 1900 MHz band for cellular telephone operation; wherein the first substrate polymer layer has a thickness range of approximately 0.6 mm to approximately 0.7 mm; and, wherein the aperture is a semi-transparent region having transparency in a range from 84% to 89%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosed embodiments will be described with reference to the accompanying drawings.

(2) FIG. 1 is an exploded isometric view of a preferred embodiment.

(3) FIG. 2 is an exploded isometric view of a preferred embodiment.

(4) FIG. 3 is an isometric view of a preferred embodiment in use.

(5) FIG. 4 is an isometric view of a preferred embodiment in use.

(6) FIG. 5 is an exploded isometric view of a preferred embodiment in use.

(7) FIG. 6 is a plot of an electromagnetic radiation pattern in a curved plane produced by a cellular telephone.

(8) FIG. 7 is a plot of an electromagnetic radiation pattern in a curved plane produced by a cellular telephone utilizing a preferred embodiment.

(9) FIG. 8 is an isometric view of a cellular telephone.

(10) FIG. 9A is a graph of an electromagnetic radiation pattern measured from a cellular telephone and a cellular telephone utilizing a preferred embodiment along an x-axis.

(11) FIG. 9B is a graph of an electromagnetic radiation pattern measured from a cellular telephone of the prior art and a cellular telephone utilizing a preferred embodiment along a y-axis.

(12) FIG. 9C is a graph of an electromagnetic radiation pattern measured from a cellular telephone of the prior art and a cellular telephone utilizing a preferred embodiment along a z-axis.

DETAILED DESCRIPTION

(13) Referring to FIG. 1, radiation shield 100 comprises a substrate polymer layer 101, a scratch resistant layer 104, conductive layer 102, and adhesive layer 103, polymer layer 101, opening 107, and opening 108. Conductive layer 102 has apertures 109, 110 and 111. Adhesive layer 103 has attachment surface 105, tack surface 106, opening 112, and opening 113.

(14) In a preferred embodiment, substrate polymer layer 101 is comprised of a polyester substrate having a thickness of between about 0.01 mm and 0.02 mm.

(15) In a preferred embodiment, substrate polymer layer 101 is comprised of polyethylene terephthalate (PET) having a thickness of between about 0.5 mm and 1.0 mm.

(16) In a preferred embodiment, substrate polymer layer 101 is a glass material having a thickness of between about 0.5 millimeters and 1.0 millimeters. Preferred glasses include 75% silica glass having non-metallic doping.

(17) In another embodiment, substrate polymer layer 101 is comprised of a polycarbonate material having a thickness of between about 0.5 millimeters and 1.0 millimeters. Preferred polycarbonate materials are LEXAN, MAKROKOM or MAKROCLEAN available from Sabic Innovative Plastics and Aria Plast AB of Sweden, respectively.

(18) In a preferred embodiment, scratch resistant layer 104 is a scratch resistant material having a thickness of between about 0.01 millimeters and 0.02 millimeters. In a preferred embodiment, the scratch resistant surface is an acrylic coating or magnesium fluoride applied by spraying during manufacture.

(19) In a preferred embodiment, conductive layer 102 is a metallic coating which is applied to the substrate polymer, having a thickness of between approximately 0.03 millimeters and 0.06 millimeters and a sheet resistance of between about 10 ohms per square and about 15 ohms per square. Preferred methods of manufacture include sputtering and vapor deposition of the metallic layer onto the substrate polymer. Apertures 109 and 111 do not have conductive layer 102. In a preferred embodiment, the substrate polymer is masked during application of the conductive layer to create apertures 109, 110 and 111. The apertures provide several functions. First, they allow the touch-sensitive screen of modern cellphones to function. Second, they provide sufficient visibility to all the cellular telephone display to be seen. Also, the partial metal coating remaining after etching provides additional electromagnetic shielding properties. In other embodiments, the conductive layer is removed after deposition by laser or chemical etching, particularly hydrochloric acid or nitric acid. Conductive layer 102 is preferably comprised of indium tin oxide having a transparency of at least 84% light transmission upon application. Other conductive materials such as silver, gold, and carbon nanotubes or graphene will also suffice. Conductive polymers can also be used with success, such as polyacetylene, polyphenylenen vinylene, polythophene and polyphylene sulfide. Similarly, conducting polymer nanofibers can be used with success, particularly polyaniline nanofibers and carbon nanofibers.

(20) In a preferred embodiment, adhesive layer 103 is a transparent adhesive having a thickness of between about 0.035 and 0.065 millimeters. Ideally, the adhesive coating adheres permanently to conductive layer 102, but enables tack surface 106 to be removed and repositioned on surfaces of a cellular telephone. In a preferred embodiment, the adhesive is No. 7651 adhesive available from Dow Corning Corporation of Midland, Mich., has an adhesive strength range of approximately 1.97 grams per meter (g/m) to approximately 3.94 grams per meter (g/m). Other adhesives with suitable transparent properties will also suffice.

(21) In another embodiment, adhesive layer 103 comprises a polymer coating suitable for static adherence to the face of a cellular telephone.

(22) Referring to FIG. 2, an alternative embodiment is shown. Radiation shield 200 comprises scratch resistant layer 205, first substrate polymer layer 201, conductive layer 202, second substrate polymer layer 203, and adhesive layer 204. First substrate polymer layer 201 has openings 208, 209, and 210. Conductive layer 202 attaches to first substrate polymer layer 201. Conductive layer 202 has openings 211, 212, and 213, and aperture 214. Second polymer layer 203 attaches to conductive layer 202. Second substrate polymer layer 203 has openings 215, 216, and 217. Adhesive layer 204 attaches to second substrate polymer layer 203. Adhesive layer 204 has attachment surface 206, tack surface 207, and openings 218, 219, and 220.

(23) In a preferred embodiment, scratch resistant layer 205 is a magnesium fluoride coating of between about 0.01 millimeters and 0.015 millimeters, applied through vapor deposition.

(24) In a preferred embodiment, first substrate polymer layer 201 is made of a polyester substrate having a thickness of between about 0.1 millimeters and 0.7 millimeters.

(25) In a preferred embodiment, first substrate polymer layer 201 is comprised of polyethylene terephthalate (PET) having a thickness of between about 0.1 mm and 0.7 mm.

(26) In another embodiment, first substrate polymer layer 201 is made of a glass material having a thickness of between about 0.1 millimeters and 0.7 millimeters. Preferred glasses include 75% silica glass having non-metallic doping.

(27) In another embodiment, first substrate polymer layer 201 is made of a polycarbonate material having a thickness of between about 0.1 millimeters and 0.7 millimeters. Preferred polycarbonates are LEXAN, MAKROKOM or MAKROCLEAN available from Sabic Innovative Plastics and Aria Plast AB of Sweden, respectively.

(28) In a preferred embodiment, second substrate polymer layer 203 has a thickness of between about 0.1 millimeters and 0.7 millimeters.

(29) In a preferred embodiment, second polymer layer 203 is made of a polyester substrate having a thickness of between about 0.1 millimeters and 0.7 millimeters.

(30) In a preferred embodiment, second substrate polymer layer 203 is comprised of polyethylene terephthalate (PET) having a thickness of between about 0.1 mm and 0.7 mm.

(31) In another embodiment, second substrate polymer layer 203 is made of a glass material having a thickness of between about 0.25 millimeters and 0.5 millimeters. Preferred glasses include 75% silica glass having non-metallic doping.

(32) In another embodiment, second substrate polymer layer 203 is made of a polycarbonate material having a thickness of between about 0.1 millimeters and 0.7 millimeters. Preferred polycarbonates are LEXAN, MAKROKOM or MAKROCLEAN available from Sabic Innovative Plastics and Aria Plast AB of Sweden, respectively.

(33) In a preferred embodiment, conductive layer 202 is a metallic coating which is applied to the substrate polymer, having a thickness of between approximately 0.03 millimeters and 0.06 millimeters and a sheet resistance of between about 10 ohms per square and about 15 ohms per square. Preferred methods of manufacture include sputtering and vapor deposition of the metallic layer onto the substrate polymer. Openings 211, 212, 213 and aperture 214 do not have conductive layer 202. In a preferred embodiment, the substrate polymer is masked during application of the conductive layer to create openings 211, 212, 213 and aperture 214. In other embodiments, the conductive layer is removed after deposition by laser or chemical etching, particularly hydrochloric acid or nitric acid. Conductive layer 202 is preferably comprised of indium tin oxide having a transparency of at least 84% light transmission upon application. Other conductive materials such as silver, gold, and carbon nanotubes or graphene will also suffice. Conductive polymers can also be used with success, such as polyacetylene, polyphenylenen vinylene, polythophene and polyphylene sulfide. Similarly, conducting polymer nanofibers can be used with success, particularly polyaniline nanofibers and carbon nanofibers.

(34) In a preferred embodiment, adhesive layer 204 is a transparent adhesive having a thickness of approximately 0.035 and 0.065 millimeters and properties that enable it to permanently adhere to second polymer layer 203 and yet enable tack surface 207 to removably attach to flat surfaces on a cellular telephone. In a preferred embodiment, the adhesive is No. 7651 adhesive available from Dow Corning Corporation of Midland, Mich., has an adhesive strength range of approximately 1.97 grams per meter (g/m) to approximately 3.94 grams per meter (g/m). Other adhesives with suitably transparent properties will also suffice.

(35) Referring to FIG. 3, an application of an assembled radiation shield to a cellular telephone is shown. Radiation shield 301 has aperture 302, openings 303 and 304. The shield includes exposed scratch resistant surface 305 and exposed tack surface 306. Exemplary cellular telephone 401 has front surface 402, speaker 403, screen 404, trackball 405, and keyboard 406. Opening 303 approximately matches speaker 403. Opening 304 approximately matches the dimensions of keyboard 406 and trackball 405. Aperture 302 has a set of dimensions sized to approximately match the dimensions of screen 404.

(36) In the assembled radiation shield 301 includes aperture 302. Aperture 302 is an area of the shield where conductive layer 307 is not present. In this embodiment, openings 303 and 304 extend through radiation shield 301. Aperture 302 allows screen 404 to properly function. Aperture 302 is largely transparent due to the transparency of the substrate polycarbonate layer and the scratch resistant layer. The transparency allows transmission of the light from the screen of the cellular telephone. Opening 304 allows controls of the cellular telephone to be easily accessed. Similarly, opening 303 allows sound from the speaker to exit the phone unhindered.

(37) In a preferred embodiment, tack surface 306 is adhered to front surface 402 by static attraction.

(38) Referring to FIG. 4, another embodiment is shown. Radiation shield 350 includes aperture 351, openings 352, 353, and 354, scratch resistant surface 355, tack surface 356, and conductive layer 357. Cellular telephone 451 has front outside surface 452, speaker 453, camera 454, touch-sensitive screen 455, and button 456. Aperture 351 has a set of dimensions that are approximately equal to the dimensions of touch-sensitive screen 455. Opening 352 is sized to approximately match speaker 453. Opening 353 is sized to approximately match camera 454. Opening 354 is sized to approximately match button 456.

(39) In the assembled radiation shield 350 includes aperture 351. Aperture 351 is an area of the shield where conductive layer 357 is not present. In this embodiment, openings 352, 353 and 354 extend through radiation shield 350. Aperture 351 allows touch-sensitive screen 455 to maintain touch-sensitive functionality. Aperture 351 is largely transparent due to the transparency of the substrate polycarbonate layer and the scratch resistant layer. The transparently allows transmission of the light from the screen of the cellular telephone. Opening 303 allows controls of the cellular telephone to be easily accessed. Similarly, opening 352 allows sound from the speaker to exit the phone unhindered.

(40) In a preferred embodiment, tack surface 356 is adhered to front surface 452 by static attraction.

(41) Referring to FIG. 5, another embodiment is shown. In this embodiment, radiation shield 350 is shown positioned inside a cellular telephone assembly. In this embodiment, radiation shield 350 has the same layered construction as radiation shield 200 of FIG. 2, except radiation shield 350 does not include adhesive layer 204 or scratch resistant layer 205. Cellular telephone 451 includes base 461 and cover 462. Base 461 includes speaker 453, camera 454, screen 455, and button 456. Cover 462 includes front outside surface 452 and front inside surface 464. Radiation shield 350 is located inside cellular telephone 451 between base 461 and cover 462, and adjacent front inside surface 464.

(42) Tests were conducted to measure the specific absorption rate produced by three cellular telephones with and without the radiation shield at a location on a simulated human head. In the following tests, the sample volume is 1 gram of tissue.

(43) The detection system used in each test was a DASY52 dosimetric scanner manufactured and sold by Schmid & Partner Engineering AG of Zurich, Switzerland (SPEAG) having an EX3DV3 probe attached to the DASY52 scanner. The simulated human head called a phantom was a SAM2 phantom manufactured and sold by SPEAG. The sensor position was swept robotically through multiple positions within the phantom to measure the electromagnetic radiation produced by the cellular telephone.

(44) Test 1 Results

(45) FIG. 6 shows a map of radiated power as measured in the matching fluid. Cellular telephone 10 was positioned in contact with surface 11 at a perpendicular tangent at electromagnetic radiation source 25 on surface 11. Equipotential lines 12, 13, and 14 of the electromagnetic radiation are mapped on surface 11. The cellular device emitted approximately two (2) watts peak power. Equipotential lines 12, 13, and 14 have values of approximately 0.783 mW/g, 0.626 mW/g, and 0.470 mW/g, respectively. Equipotential lines 12, 13, and 14 appear as radial distances from electromagnetic radiation source 25 of approximately 1.5, 2.5, and 2.8 centimeters, respectively.

(46) Referring to FIG. 7, radiation shield 15 is shown attached to cellular telephone 10. Equipotential lines 16, 17, and 18 are mapped on surface 11 when cellular telephone with radiation shield 15 is use. Equipotential lines 16, 17, and 18 have values of approximately 0.697 mW/g, 0.559 mW/g, and 0.457 mW/g, respectively. Equipotential lines 16, 17, and 18 appear as radial distances from electromagnetic radiation source 25 of approximately 1.5, 2.8, and 3.0 centimeters, respectively.

(47) Comparing FIGS. 6 and 7, it is seen that the radiation shield 15 attenuates the electromagnetic radiation directed toward the human head from a cellular telephone 10. Equipotential lines 16, 17, and 18 are attenuated by as much as 30% when compared to equipotential lines 12, 13, and 14 in distance. As a result, radiation levels are reduced across surface 11 thereby reducing radiation absorbed by the human tissue.

(48) Test 2 Results

(49) Test 2 measured the SAR level produced by the Apple iPhone 4 cellular telephone positioned against the right-hand side of the simulated human head. Three SAR levels were tested: a baseline SAR level produced with no radiation shielding attached; a SAR level produced with radiation shield 200 attached to the phone; and a SAR level produced with a portion of the lower section removed.

(50) The results of Test 2 are listed in Table 1 below.

(51) TABLE-US-00001 TABLE 1 Apple iPhone 4 SAR Measurement Results SAR Frequency Side of 1 g Device Band Channel (MHz) Mode Head (W/kg) iPhone 4 Cell 189 836.60 GSM Right 0.823 (baseline) Voice iPhone 4 with Cell 189 836.60 GSM Right 0.134 Radiation Shield Voice iPhone 4 with Cell 189 836.60 GSM Right 0.712 Radiation Shield Voice with lower section removed to expose cellular antenna

(52) Test 3 Results

(53) Test 3 measured the SAR level produced by the Apple iPhone 3 cellular telephone positioned against the right-hand side ear and the left-hand side ear of the simulated human head. Eight SAR levels produced by the Apple iPhone 3 cellular telephone were measured, with and without the radiation shield attached to the cellular telephone: four SAR levels with the cellular telephone operating in the 800 MHz band; and four SAR levels with the cellular telephone operating in the 1900 MHz PCS band. A baseline SAR level was measured from the phone with no radiation shielding attached.

(54) The results of Test 3 are listed in Table 2 below.

(55) TABLE-US-00002 TABLE 2 Apple iPhone 3 SAR Measurement Results SAR Frequency Side of 1 g Device Band Channel (MHz) Mode Head (W/kg) iPhone 3 Cell 189 836.60 GSM Right 0.418 (baseline) Voice iPhone 3 with Cell 189 836.60 GSM Right 0.311 Radiation Shield Voice iPhone 3 Cell 189 836.60 GSM Left 0.371 (baseline) Voice iPhone 3 with Cell 189 836.60 GSM Left 0.314 Radiation Shield Voice iPhone 3 PCS 661 1880.0 GSM Right 1.250 (baseline) Voice iPhone 3 with PCS 661 1880.0 GSM Right 0.307 Radiation Shield Voice iPhone 3 PCS 661 1880.0 GSM Left 0.997 (baseline) Voice iPhone 3 with PCS 661 1880.0 GSM Left 0.290 Radiation Shield Voice

(56) Test 4 Results

(57) Test 4 measured the SAR level produced by the HTC Evo cellular telephone positioned against the right-hand side ear and the left-hand side ear of the simulated human head. Eight SAR levels produced by the phone were measured, with and without an embodiment of the radiation shield disclosed herein attached to the phone: four SAR levels with the phone operating in the 800 MHz band; and four SAR levels with the phone operating in the 1900 MHz PCS band. A baseline SAR level was measured from the phone operating with no radiation shielding attached, at each head band of operation.

(58) The results of Test 4 are listed in Table 3 below.

(59) TABLE-US-00003 TABLE 3 HTC Evo SAR Measurement Results Fre- Side SAR quency of 1 g Device Band Channel (MHz) Mode Head (W/kg) HTC Evo Cell 384 836.52 CDMA- Right 0.737 (baseline) RC3/SO55 HTC Evo with Cell 384 836.52 CDMA- Right 0.659 Radiation Shield RC3/SO55 HTC Evo Cell 384 836.52 CDMA- Left 0.900 (baseline) RC3/SO55 HTC Evo with Cell 384 836.52 CDMA- Left 0.816 Radiation Shield RC3/SO55 HTC Evo PCS 600 1880.0 CDMA- Right 1.620 (baseline) RC3/SO55 HTC Evo with PCS 600 1880.0 CDMA- Right 0.989 Radiation Shield RC3/SO55 HTC Evo PCS 600 1880.0 CDMA- Left 1.800 (baseline) RC3/SO55 HTC Evo with PCS 600 1880.0 CDMA- Left 1.170 Radiation Shield RC3/SO55

(60) Referring to FIGS. 8, 9A-9C, components of the electromagnetic power emitted by a cellular telephone with and without a radiation shield present are plotted x-axis 30, y-axis 21 and z-axis 22 related to a cellular phone body. Cellular telephone 10 has surface 23 and electromagnetic radiation source 25. X-axis 30 extends parallel to surface 23, through electromagnetic radiation source 25. Y-axis 21 extends parallel to surface 23, through electromagnetic radiation source 25 and parallel to height 24. Z-axis 22 extends perpendicular to both y-axis 21 and x-axis 30 and perpendicularly from surface 23 through electromagnetic radiation source 25.

(61) Referring to FIG. 9A, curve 81 shows the power, measured in milliWatts (mW), at distances along x-axis 30 from electromagnetic radiation source 25 with no radiation shielding. Curve 85 shows the power in mW at distances along x-axis 30 from electromagnetic radiation source 25 with radiation shield 15 attached to cellular telephone 10.

(62) Curve 85 shows the power, measured in milliWatts (mW), at distances along the x-axis from electromagnetic radiation source 25 with radiation shield 15 adhered to the surface of electromagnetic radiation source 25. The power is significantly less than the power measured with no radiation shield. Point 80 shows a peak power of approximately 0.780 mW. Point 83 shows a power of approximately 0.157 mW. Point 84 shows a peak power of approximately 0.697 mW. Point 86 shows a power of approximately 0.152 mW.

(63) Referring to FIG. 9B, curve 88 shows the power, measured in milliWatts (mW), at distances along y-axis 21 from electromagnetic radiation source 25 with no radiation shielding. Curve 91 shows the power in mW at distances along y-axis 21 from electromagnetic radiation source 25 with radiation shield 15 attached to cellular telephone 10.

(64) Curve 91 shows the power, measured in milliWatts (mW), at distances along the y-axis from electromagnetic radiation source 25 with radiation shield 15 adhered to the surface of electromagnetic radiation source 25. The power is significantly less than the power measured with no radiation shield. Point 87 shows a peak power of approximately 0.780 mW. Point 89 shows a power of approximately 0.157 mW. Point 90 shows a peak power of approximately 0.697 mW. Point 92 shows a power of approximately 0.152 mW.

(65) Referring to FIG. 9C, curve 94 shows the power, measured in milliWatts (mW), at distances along z-axis 22 from electromagnetic radiation source 25 with no radiation shielding. Curve 97 shows the power in mW at distances along z-axis 22 from electromagnetic radiation source 25 with radiation shield 15 attached to cellular telephone 10.

(66) Curve 97 shows the power, measured in milliWatts (mW), at distances along the x-axis from electromagnetic radiation source 25 with radiation shield 15 adhered to the surface of electromagnetic radiation source 25. The power is significantly less than the power measured with no radiation shield. Point 93 shows a peak power of approximately 0.780 mW. Point 95 shows a power of approximately 0.157 mW. Point 96 shows a peak power of approximately 0.697 mW. Point 98 shows a power of approximately 0.152 mW.

(67) It will be appreciated by those skilled in the art that modifications can be made to the embodiments disclosed and remain within the inventive concept. Therefore, this invention is not limited to the specific embodiments disclosed, but is intended to cover changes within the scope and spirit of the claims.