Magnetic field shielding sheet for digitizer and method of manufacturing the same and portable terminal device using the same

• US 9,392,735 B2
• Filed: 06/04/2013
• Issued: 07/12/2016
• Est. Priority Date: 06/04/2012
• Status: Active Grant

• Current Assignee: Amosense Co., Ltd.
• Original Assignee: Amosense Co., Ltd.
• Inventors: Jang, Kil Jae, Lee, Dong Hoon, Lee, Byoung Ki
• Primary Examiner(s): Ngo, Hung V
• Application Number:
  US14/405,502
• Publication Number:
  US 20150124402A1
• Time in Patent Office: 1,134 Days
• US Class Current: 1/1
• CPC Class Codes: B32B 2307/208 Magnetic, paramagnetic
• CPC Class Codes: B32B 2307/212 Electromagnetic interference shielding
• CPC Class Codes: B32B 2307/702 Amorphous
• CPC Class Codes: B32B 2307/748 Releasability
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/04 Time
• CPC Class Codes: B32B 2309/105 Thickness
• CPC Class Codes: B32B 2457/00 Electrical equipment
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/281 comprising polyimides
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: B32B 38/00 Ancillary operations in connection with laminating processes
• CPC Class Codes: B32B 38/0036 Heat treatment for heating or cooling of layers during lamination B32B37/06, B32B37/08
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C21D 6/00 Heat treatment of ferrous alloys
• CPC Class Codes: G06F 1/1643 the display being associated to a digitizer, e.g. laptops that can be used as penpads details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615
• CPC Class Codes: G06F 1/182 with special features, e.g. for use in industrial environments; grounding or shielding against radio frequency interference [RFI] or electromagnetical interference [EMI]
• CPC Class Codes: H01F 1/15308 based on Fe/Ni H01F1/15325 takes precedence
• CPC Class Codes: H01F 27/366 : made of ferromagnetic material
• CPC Class Codes: H05K 9/0075 : Magnetic shielding materials

Abstract

A magnetic field shielding sheet includes: at least one layer thin magnetic sheet made of a Fe-based amorphous alloy and flake-treated so as to be separated into a plurality of fine pieces; a protective film that is adhered on one surface of the thin magnetic sheet via a first adhesive layer provided on one side of the protective film; and a double-sided tape that is adhered on the other surface of the thin magnetic sheet via a second adhesive layer provided on one side of the double-sided adhesive tape, wherein the thin magnetic sheet is obtained by heat treating an amorphous ribbon sheet made of the Fe-based amorphous alloy at a temperature of 300° C. to 480° C. A method of manufacturing the magnetic field shielding sheet, and a portable terminal device using the magnetic field shielding sheet are disclosed.

Claims

1. A magnetic field shielding sheet for a digitizer, the magnetic field shielding sheet comprising:

at least one layer thin magnetic sheet which is flake-treated so as to be separated into a plurality of fine pieces;

a protective film that is adhered on one surface of the thin magnetic sheet via a first adhesive layer provided therebetween; and

a double-sided adhesive tape that is adhered on the other surface of the thin magnetic sheet via a second adhesive layer provided therebetween,

wherein the thin magnetic sheet is obtained by heat treating an amorphous ribbon sheet made of a Fe-based alloy at a temperature less than a crystallization temperature.

2. The magnetic field shielding sheet according to claim 1, wherein the amorphous ribbon sheet is heat treated in a temperature range of 300°

C. to 480°

C., preferably of 445°

C. to 460°

C.

3. The magnetic field shielding sheet according to claim 2, wherein an inductance value of the magnetic sheet is set to be in the range of 15 μ

H to 18 μ

H when a geomagnetic sensor is used together with the digitizer.

4. The magnetic field shielding sheet according to claim 1, wherein the amorphous ribbon sheet is formed in the range of 15 μ

m to 35 μ

m thick.

5. The magnetic field shielding sheet according to claim 1, wherein some of the first adhesive layer and the second adhesive layer are filled into the gaps between the fine pieces.

6. The magnetic field shielding sheet according to claim 1, wherein the fine pieces are formed of several tens of micrometers (μ

m) to 3 mm in size.

7. The magnetic field shielding sheet according to claim 1, wherein the thin magnetic sheet comprises:

a Fe-based alloy ribbon sheet formed of the fine pieces;

a polymer sheet that is stacked on the ribbon sheet and has a lower permeability than the ribbon sheet; and

an adhesive layer that mutually bonds the ribbon sheet and the polymer sheet.

8. The magnetic field shielding sheet according to claim 1, further comprising an auxiliary magnetic sheet that is overlapped in an annular form on one side or an outer periphery of the thin magnetic sheet.

9. The magnetic field shielding sheet according to claim 1, further comprising a conductive sheet that is formed of a thin plate on an outer surface of the protective film to thus shield an electromagnetic wave.

10. A method of manufacturing a magnetic field shielding sheet for a digitizer, the method comprising the steps of:

heat treating a Fe-based amorphous alloy ribbon sheet made at a temperature of 300°

C. to 480°

C. for 30 minutes to 2 hours, to thereby form a thin magnetic sheet;

adhering a protective film and a double-sided tape formed of a release film on an exposed surface of the double-sided tape, respectively, on both sides of the thin magnetic sheet, to thereby form a laminate sheet;

performing a flake treatment process of the laminate sheet to thus separate the thin magnetic sheet into a plurality of fine pieces; and

laminating the flake treated laminate sheet,

wherein the laminate sheet is flattened and slimmed by lamination of the laminate sheet and some parts of first and second adhesive layers are filled into gaps among the plurality of fine pieces.

11. The method of claim 10, wherein the amorphous ribbon sheet is heat treated for 30 minutes to 2 hours in a heat treatment temperature range of 445°

C. to 460°

C.

12. The method of claim 11, wherein an inductance value of the ribbon sheet is set to be in the range of 15 μ

H to 18 μ

H.

13. The method of claim 10, wherein the fine pieces are formed of several tens of micrometers (μ

m) to 3 mm in size.

14. The method of claim 10, further comprising the step of bonding a Cu or Al foil on an outer surface of the protective film after the laminating step.

15. A portable terminal device having a first magnetic field shielding sheet that is inserted between a digitizer panel and a main circuit board and shields an alternating-current (AC) magnetic field generated from the main circuit board, the first magnetic field shielding sheet comprising:

at least one layer thin magnetic sheet which is flake-treated so as to be separated into a plurality of fine pieces;

a protective film that is adhered on one surface of the thin magnetic sheet via a first adhesive layer provided therebetween; and

a double-sided adhesive tape that is adhered on the other surface of the thin magnetic sheet via a second adhesive layer provided therebetween,

wherein the thin magnetic sheet is obtained by heat treating an amorphous ribbon sheet made of a Fe-based alloy at a temperature less than a crystallization temperature.

16. The portable terminal device according to claim 15, wherein the amorphous ribbon sheet is heat treated in a temperature range of 300°

C. to 480°

C., preferably of 445°

C. to 460°

C., and an inductance value of the ribbon sheet is set to be in the range of 15 μ

H to 18 μ

H.

17. The portable terminal device according to claim 15, further comprising a geomagnetic sensor that is disposed at one corner of the main circuit board, wherein the first magnetic field shielding sheet is made in a shape corresponding to a digitizer and that is mounted at an interval from the geomagnetic sensor.

18. The portable terminal device according to claim 15, further comprising a second magnetic field shielding sheet that has a permeability higher than that of the first magnetic field shielding sheet, that is overlapped from one side of the first magnetic field shielding sheet or extended from the first magnetic field shielding sheet while being partially overlapped with the first magnetic field shielding sheet, or that is extended in a flat form from the first magnetic field shielding sheet.

19. The portable terminal device according to claim 15, further comprising a second magnetic sheet that has a permeability different from that of the first thin magnetic sheet and that is stacked on one side of the thin magnetic sheet.

20. The portable terminal device according to claim 15, wherein the first magnetic field shielding sheet further comprises a conductive sheet that is formed of a thin plate on an outer surface of the protective film to thus shield an electromagnetic wave.