Patent Description:
In recent years, portable terminal devices such as smart phones with a digitizer feature have been commercialized and become popular in the market. A digitizer using an electronic pen enables a user to draw a line of about <NUM> thick and thus is more precise than a capacitive type touch panel recognizing a line of <NUM>-<NUM> thick, to thereby perform a fine work easily.

In addition, it is possible to take handwritten notes, to draw a picture, and edit an image or photo, by using an electronic pen such as a stylus. Furthermore, pressure of a force applied to the electronic pen is detected when a user holds the electronic pen in hand to write a letter and thus thickness of the letter varies depending on the detected force, to thereby enable a work with a high resolution.

To implement such a digitizer feature, a digitizer panel is provided at a lower side of a touch screen/display panel. In addition, since the digitizer panel is formed of a thin metal film, a feeble electromagnetic field is created when the digitizer panel conducts electricity, and since a built-in ultra-small metal coil is provided at the end of the portable electronic pen, an alternating magnetic field is generated in use.

Thus, when the tip of the electronic pen is close to the touch screen, the electromagnetic induction phenomenon occurs, while deformation of the electromagnetic field that has already been formed occurs on the digitizer panel disposed below the touch screen/display panel. Here, deformation of the electromagnetic field is detected through a sensor arranged at a side edge of the digitizer panel to thereby be interpreted as the actual movement of the electronic pen.

This digitizer feature is being applied to a large screen tablet personal computer (PC) employing a large display as well as a small portable terminal device such as a smart phone.

In order to use a digitizer feature using an electromagnetic induction phenomenon in a portable terminal device, a magnetic field shield sheet for shielding an electromagnetic field generated from various components of a main body of the portable terminal device, is inserted and used between the digitizer panel and a main circuit board. The main body of the portable terminal device has a variety of communication chips and antennas and generates an electromagnetic field for wireless communications.

Recently, a spread of a long-term evolution (LTE) implementing a fourth generation mobile communication technology uses radio waves much stronger than a conventional wireless communication terminal using the <NUM> mobile communication system. Accordingly, an influence upon a digitizer from the strong electromagnetic field is precluded, and a reliable magnetic field shield is required for smooth magnetic field communications between the stylus and the digitizer.

Meanwhile, the portable terminal device includes a geomagnetic sensor in order to implement functions such as navigation or augmented reality by using GPS (Global Positioning System) technologies. In addition, in the case of smart phones employing the Android operating system (OS), it is an essential condition to adopt the geomagnetic sensor.

Since the magnetic field shield sheet is formed of a size corresponding to a digitizer, i.e., a display so as not to influence upon a digitizer function, it is difficult to design a gap between the magnetic field shield sheet and the geomagnetic sensor in the inside of the portable terminal device to become <NUM> or longer.

However, in the case that the magnetic field shield sheet is used in the portable terminal device in the proximity of and together with the geomagnetic sensor, the magnetic field shield sheet affects the geomagnetic sensor thereby causing malfunction in the geomagnetic sensor.

In other words, the geomagnetic sensor can cause azimuth distortion, sensor sensitivity distortion, and magnetic hysteresis distortion by the magnetic field shield sheet.

Azimuth distortion means a phenomenon of distorting the direction of the magnetic north due to the magnetic field shield sheet, sensor sensitivity distortion means a phenomenon of distorting the sensitivity among X-, Y-, Z-axis sensors constituting the geomagnetic sensor, since the strength of the magnetic field is also changing due to the magnetic field shield sheet, and magnetic hysteresis distortion means a phenomenon of making an error in the azimuth depending on the direction of rotation of the sensor because of the magnetic hysteresis of a magnetic substance.

Accordingly, in order to prevent the distortion of the geomagnetic sensor and in order to measure accurate azimuth, it is necessary to correct the geomagnetic sensor. However, it is possible to correct the azimuth distortion and the sensor sensitivity distortion accurately, but it is difficult to correct the magnetic hysteresis distortion accurately, to thereby weight an error of the geomagnetic sensor.

It is general to use a magnetic substance such as heatless treatment Fe-based and Co-based amorphous ribbons, ferrite sheets, or polymer sheets containing magnetic powder, as the magnetic field shield sheet. A magnetic field focusing effect to improve performance of a magnetic field shielding function and a digitizer feature, may be good in the order of high magnetic permeability Fe-based and Co-based amorphous ribbons, ferrite sheets, and polymer sheets containing magnetic powder.

Heatless treatment Fe-based and Co-based amorphous ribbons are metal sheets in themselves, and thus, have no burden to the thickness. However, heatless treatment Fe-based and Co-based amorphous ribbons have too large magnetic permeability, and thus affect the geomagnetic sensor. As a result, heatless treatment Fe-based and Co-based amorphous ribbons are not used as the magnetic field shield sheets. In addition, the ferrite sheets also have too large magnetic permeability and thus affect the geomagnetic sensor. In addition, the ferrite sheets also have drawbacks of getting thick.

Thus, the conventional magnetic field shield sheet employs a polymer sheet containing magnetic powder of a relatively poor magnetic permeability. However, when compared with the Fe-based and Co-based amorphous ribbons, the polymer sheet has low magnetic permeability, to thereby cause a problem that an electronic pen such as a stylus is very expensive and sensitivity of the stylus is degraded to the half (<NUM>/<NUM>).

In addition, since the polymer sheet has low magnetic permeability, when compared with the Fe-based and Co-based amorphous ribbons, the polymer sheet gets thick in comparison with the Fe-based and Co-based amorphous ribbons that are thin plates of several tens of micrometers (µm) in order to improve the performance of the low magnetic permeability. Accordingly, it is difficult to cope with the trend that the terminals get thin, and the material cost is further increased due to an increase of the thickness.

Meanwhile, the magnetic hysteresis phenomenon means that a magnetic body has a hysteresis that magnetic induction values in the inside of the magnetic body do not match each other when a magnetic field is applied to the magnetic body through a rise and fall of the magnetic field, and may occur in the case that the magnetic field is applied to the magnetic body until to the magnetic body is saturated. In the case that the magnetic field does not reach a saturation region, the magnetic induction values are repeatedly increased and decreased without causing any hysteresis along an initial magnetization curve.

In the case of the heatless treatment Fe-based amorphous ribbon among the amorphous ribbons, a value of a saturation field (Hs) that is the minimum magnetic field to obtain the saturation induction is about <NUM> that is lower than the earth magnetic field having a value of about <NUM>, in a magnetic hysteresis loop.

Therefore, the Fe-based amorphous ribbon sheet exhibits the magnetic hysteresis phenomenon even in the case of a change in the earth magnetic field, with the result that a geomagnetic sensor used in a terminal to which a Fe-based amorphous ribbon sheet is applied, has the fatal disadvantage that even the magnetic hysteresis phenomenon due to the Fe-based amorphous ribbon sheet should be corrected.

In addition, in the case that Fe-based and Co-based amorphous ribbon sheets are used, the geomagnetic sensor causes an azimuth hysteresis phenomenon that is generated according to the rotational direction of the geomagnetic sensor in the X-axis, Y-axis, and Z-axis sensed values when the geomagnetic sensor is rotated in the clockwise direction and the counterclockwise direction, and an azimuth hysteresis phenomenon is not accurately calibrated thereby weighting errors to the sensor operation.

Meanwhile, <CIT> proposed an electromagnetic wave absorbing sheet containing a Fe-based nanocrystalline soft magnetic powder and a carbon-based conductive material powder. The Fe-based nanocrystalline soft magnetic powder is formed of a Fe-Si-B-Nb-Cu-based alloy as an amorphous alloy. The Fe-Si-B-Nb-Cu-based alloy is preliminarily heat treated at a temperature of <NUM> to <NUM> for <NUM>-<NUM> minutes, to thus obtain alloy powders, the alloy powders are primarily and secondarily crushed, and then the crushed powders are meshed to be <NUM> mesh in particle size, to thereby obtain Fe-based nanocrystalline soft magnetic powders having nano-sized crystal grains.

The electromagnetic wave absorbing sheet is made to have a thickness of <NUM>, to thus absorb <NUM> to <NUM> band electromagnetic waves.

However, the electromagnetic wave absorbing sheet is simply used to absorb the high frequency band electromagnetic waves, and employs a kind of polymer sheet that is made to have a thickness of <NUM> by mixing a Fe-based nanocrystalline soft magnetic powder having nano-sized crystal grains, with a binder. As a result, the electromagnetic wave absorbing sheet gets thick when compared with the case of using the amorphous ribbon sheet (whose thickness is about <NUM> or less), and also has a low magnetic permeability due to the mixture of the binder.

<CIT> discloses a metal and polymer composite having a low frequency magnetic field shielding function, wherein at least one selected from Permalloy®, Sendust®, and a rapidly solidified alloy that are metal alloys having a high magnetic permeability is included by <NUM> to <NUM> wt% in a powdered, flaky or fibrous form; a soft polymer material is included by <NUM> to <NUM> wt% as a matrix where the metal alloys are dispersed; and various additives are included by <NUM> to <NUM> wt% in order to be used to mix the metal alloys and the soft polymer material.

Further, the Permalloy® is magnetically heat treated under the magnetic field of <NUM> to <NUM> gauss and at a temperature of <NUM> to <NUM> for <NUM>-<NUM> hours, the Sendust® is magnetically heat treated under the magnetic field of <NUM> to <NUM> gauss and at a temperature of <NUM> to <NUM> for <NUM>-<NUM> hours, and the rapidly solidified alloy is magnetically heat treated under the magnetic field of <NUM> to <NUM> gauss and at a temperature of <NUM> to <NUM>, for <NUM>-<NUM> hours.

The metal and polymer composite includes a metal alloy and a polymer material in a powdered, flaky or fibrous form, and thus has the same problem as the polymer sheet.

Further, the <CIT> describes a magnetic field shielding sheet for a wireless charger and a method for manufacturing the magnetic field shielding sheet. The sheet comprises, among others, a thin magnetic sheet made of an amorphous ribbon which is obtainable by heat treating an amorphous ribbon sheet for <NUM> to <NUM> hours in a selected temperature range so as to obtain a high permeability. <CIT> discloses a method of manufacturing an electromagnetic wave shielding material by using a metal foil ribbon of high magnetic permeability, the method including: preparing a metal foil ribbon with a metal or alloy by performing a quenching solidification method; annealing the metal foil ribbon in a temperature range of <NUM> to <NUM> and under a hydrogen or vacuum atmosphere; and forming an adhesive layer on at least one surface of the metal foil ribbon.

The aforementioned prior art discloses an electromagnetic wave absorbing sheet or a magnetic field shield sheet. However, when both an electronic pen function (i.e., a stylus function) and a navigation function are implemented in a portable terminal device such as a smart phone, the above-described conventional magnetic field shield sheet does not propose a possible solution to the problems that a distortion problem for the geomagnetic sensor is present, the thickness of the magnetic field shield sheet gets thick, and the material cost for the magnetic field shield sheet is very expensive.

Taking into account that the distortion of the azimuth and the sensor sensitivity distortion among the distortions that occur in the geomagnetic sensor due to the shield sheet can be accurately corrected, but the directional hysteresis due to the magnetic hysteresis phenomenon cannot be accurately corrected, the inventor(s) has tried to develop shield sheets that do not cause the distortion problem due to the magnetic hysteresis phenomenon, and seen that there may be little change in the magnetic permeability even though the thin-film ribbon is flaked in the case of the nanocrystalline ribbon and there is no distortion problem due to the magnetic hysteresis phenomenon because of no magnetic saturation, which leads the inventor(s) to the present invention.

In the case of using a digitizer function in a smart phone such as a conventional tablet PC or a tablet phone, the digitizer function is not activated until a sufficient force is applied onto tempered glass provided on a touch screen panel or a display panel with the tip of the electronic pen so as to feel the pressure of the tip of the electronic pen. In addition, the thickness of the character may be changed by detecting the intensity of the pressure of the tip of the electronic pen. Therefore, it is required to implement a contactless pen function for ease of use, improvement of durability, and improvement of sensitivity of the digitizer function.

To solve the above problems or defects, it is an object of the present invention to provide a magnetic field shield sheet for a digitizer, and a manufacturing method thereof, which enables a B-H loop (i.e., a curve between the magnetic flux density and the magnetic field intensity) to be changed in an initial magnetization curve, shield sheets of desired specific magnetic permeability to be easily manufactured, and the magnetic permeability of shield sheets to be selected widely, by performing superheating treatment at a temperature above a critical temperature, when a nanocrystalline ribbon having a nanocrystalline microstructure is manufactured by heat treatment of an amorphous alloy ribbon or strip.

It is another object of the present invention to provide a magnetic field shield sheet for a digitizer, which can shield an electromagnetic field generated from various components of a main body of a portable terminal device when a digitizer function is implemented in the portable terminal device, while minimizing an influence upon a geomagnetic sensor, and can improve the sensitivity of an electronic pen such as a stylus, a manufacturing method thereof, and a portable terminal device having a digitizer function.

It is still another object of the invention to provide a portable terminal device having a magnetic field shield sheet for a digitizer, which does not nearly generate measurement errors of the azimuth of a geomagnetic sensor due to a magnetic hysteresis phenomenon in a heatless treatment Fe-based or Co-based amorphous ribbon, and which establishes a magnetic main body of a portable terminal device when a digitizer function is implemented in the portable terminal device, while minimizing an influence upon a geomagnetic sensor, and can improve the sensitivity of an electronic pen such as a stylus, a manufacturing method thereof, and a portable terminal device having a digitizer function.

It is still another object of the invention to provide a portable terminal device having a magnetic field shield sheet for a digitizer, which does not nearly generate measurement errors of the azimuth of a geomagnetic sensor due to a magnetic hysteresis phenomenon in a heatless treatment Fe-based or Co-based amorphous ribbon, and which establishes a magnetic permeability of the magnetic field shield sheet to be higher than a polymer sheet, and to be equal to or higher than the heatless treatment Fe-based or Co-based amorphous ribbon, so as to absorb a magnetic flux required to perform a digitizer function at a high sensitivity, to thereby enable the digitizer function to be performed at a non-contact state of a wireless electronic pen on a display surface of the portable terminal device, and to thus achieve ease of use and improvement of durability.

It is yet another object of the invention to provide a magnetic field shield sheet for a digitizer, and a manufacturing method thereof, which can maximize a magnetic permeability for a magnetic shielding function by using a nanocrystalline ribbon having a nanocrystalline microstructure that is obtained by heat treating an amorphous alloy ribbon or strip, and which can increase a demagnetizing field by a flake treatment process so as not to achieve magnetic saturation, to thus block a distortion problem due to a magnetic hysteresis phenomenon.

It is yet still another object of the invention to provide a magnetic field shield sheet for a digitizer, and a manufacturing method thereof, which fills a gap between fine pieces of a nanocrystalline ribbon with an adhesive by performing a flake treatment process of the nanocrystalline ribbon and then by performing a compression laminating process, to thereby prevent water penetration, and which simultaneously surrounds all surfaces of the fine pieces with the adhesive (or the dielectric) to thus mutually isolate the fine pieces to thereby promote reduction of eddy currents and prevent shielding performance from falling.

It is a further object of the present invention to provide a magnetic field shield sheet for a digitizer, and a manufacturing method thereof, which sequentially performs a flake treatment process and a laminating process by using a roll-to-roll method, to thereby achieve a sheet molding process to thus maintain the original thickness of the sheet and to thus exhibit.

According to another aspect of the present invention, there is provided a method of manufacturing a magnetic field shield sheet for a digitizer, the method comprising the steps of:.

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, to thereby isolate the plurality of fine pieces.

According to still another aspect of the present invention, there is provided a portable terminal device having a magnetic field shield 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, wherein the magnetic field shield sheet comprises:.

Some parts of first and second adhesive layers are filled into gaps among the plurality of fine pieces, to thereby isolate the plurality of fine pieces, and a B-H loop that is a curve between a magnetic flux density and a magnetic field intensity of the first magnetic sheet is changed in an initial magnetization curve.

As described above, the present invention provides a magnetic field shield sheet that does not cause a distortion problem due to a magnetic hysteresis phenomenon, by considering that an azimuth distortion and a sensor sensitivity distortion among distortions that occur in a geomagnetic sensor due to the magnetic field shield sheet can be accurately corrected, but the directional hysteresis due to the magnetic hysteresis phenomenon cannot be accurately corrected. As a result, the magnetic field shield sheet according to the present invention does not generate a distortion problem due to a magnetic hysteresis phenomenon but generates only an azimuth distortion and sensor sensitivity distortion, to thus solve the distortions through compensation and to thereby implement a distortion-free navigation function.

To this end, the present invention performs a superheating treatment at a temperature above a critical temperature, when a nanocrystalline ribbon sheet having a nanocrystalline microstructure is manufactured by heat treatment of an amorphous alloy ribbon or strip, to thereby enable a B-H loop (i.e., a curve between the magnetic flux density and the magnetic field intensity) to be changed in an initial magnetization curve, shield sheets of desired specific magnetic permeability to be easily manufactured, and the magnetic permeability of shield sheets to be selected widely.

In addition, the present invention can control a magnetic permeability of a shield sheet according to a heat treatment temperature into a desired value, to thus easily control the magnetic permeability of the shield sheet so as to absorb a magnetic flux required to perform a digitizer function at a high sensitivity.

Further, the magnetic field shield sheet of the present invention can shield an electromagnetic field generated from various components of a main body of a portable terminal device when a digitizer function is implemented in the portable terminal device, while minimizing the influence upon a geomagnetic sensor, and can improve the sensitivity of an electronic pen such as a stylus, on behalf of a polymer sheet that is expensive and has a low magnetic permeability, and a heatless treatment Fe-based or Co-based amorphous ribbon sheet having an advantage in the thickness and excellent magnetic permeability characteristics but generating a magnetic hysteresis distortion in a geomagnetic sensor.

Considering that magnetic permeability characteristics almost do not change although the thin ribbon is flaked, in the case of nanocrystalline ribbon, the surface resistance of the ribbon is heightened by heat treatment and the ribbon is flake-treated after the heat-treatment, to thereby reduce the surface area of the ribbon, to thus increase a demagnetizing field to prevent magnetic saturation, and to thus reduce losses due to eddy current.

To this end, the present invention can maximize a magnetic permeability for a magnetic shielding function by using a nanocrystalline ribbon having a nanocrystalline microstructure that is obtained by heat treating an amorphous alloy ribbon or strip, and can increase a demagnetizing field by a flake treatment process so as not to achieve magnetic saturation, to thus block a distortion problem due to a magnetic hysteresis phenomenon.

A nanocrystalline ribbon sheet of the present invention is separated into a number of fine pieces and/or is formed of cracks, through a flake treatment process. For this reason, even in the case that a magnetic field is applied from the outside along one side of the nanocrystalline ribbon sheet, the magnetic field is attenuated while passing through a number of the fine pieces, and thus is not nearly dissipated on the opposite side of the nanocrystalline ribbon sheet to which the magnetic field has been applied.

As a result, the present invention has little effect on the geomagnetic sensor even in the case that a magnetic field is applied from the outside along one side of the nanocrystalline ribbon sheet, when the magnetic field shield sheet having a nanocrystalline ribbon sheet is used in a portable terminal device.

In the present invention, differently from a heatless treatment Fe-based or Co-based amorphous ribbon, the shield sheet does not generate a magnetic hysteresis phenomenon, and thus errors of the azimuth of the geomagnetic sensor can be removed through a compensation algorithm. In addition, the shield sheet according to the present invention has a higher magnetic permeability characteristic than the polymer sheet, to thereby improve a pen function, and provide an advantage that the azimuth errors of the geomagnetic sensor are not almost generated.

In the case that the nanocrystalline ribbon that is manufactured through such a heat treatment and flake treatment process is used as a magnetic field shield sheet, the losses due to the eddy current are greatly reduced. Accordingly, performance of the digitizer function is maximized and the magnetic field is shielded, to thereby implement a portable terminal device so as not to affect components such as a battery in the portable terminal device.

In addition, the present invention does not nearly generate measurement errors of the azimuth of a geomagnetic sensor due to a magnetic hysteresis phenomenon in a Fe-based or Co-based amorphous ribbon, and establishes a magnetic permeability of the magnetic field shield sheet to be higher than a polymer sheet, and to be equal to or higher than the Fe-based or Co-based amorphous ribbon, so as to absorb a magnetic flux required to perform a digitizer function at a high sensitivity, to thereby enable a wireless electronic pen to be performed at a non-contact state on a display surface of the portable terminal device, and to thus achieve ease of use and improvement of durability.

Moreover, the present invention fills a gap between fine pieces of a nanocrystalline ribbon with an adhesive by performing a flake treatment process of the nanocrystalline ribbon and then by performing a compression laminating process, to thereby prevent water penetration, and simultaneously surrounds all surfaces of the fine pieces with the adhesive (or the dielectric) to thus mutually isolate the fine pieces to thereby promote reduction of eddy currents and prevent shielding performance from falling.

In addition, the present invention sequentially performs a flake treatment process and a laminating process by using a roll-to-roll method, to thereby achieve a sheet molding process to thus maintain original thickness of the sheet and to thus exhibit high productivity and inexpensive manufacturing costs.

The above and other objects, features, and advantages of the present invention can be appreciated by the following description and will be understood more clearly by embodiment of the present invention. In addition, it will be appreciated that the objects and advantages of the present invention will be easily realized by means shown in the appended patent claims, and combinations thereof.

Further, if it is determined that the detailed description of the known art related to the present invention makes the gist of the present invention unnecessarily obscure, a detailed description thereof will be omitted.

Referring to <FIG>, a magnetic field shield sheet <NUM> according to an embodiment of the present invention includes: at least one layer or a double-layer nanocrystalline ribbon sheet <NUM>, by thermally treating an amorphous alloy ribbon or strip (hereinafter, simply called a "ribbon") as a thin magnetic sheet, to have nanocrystalline microstructures, and then performing a flake treatment process to be separated and/or cracked into a plurality of fine pieces <NUM>; a protective film <NUM> that is adhered on one side of the nanocrystalline ribbon sheet <NUM>; a double-sided tape <NUM> that is adhered on the other side of the nanocrystalline ribbon sheet <NUM>; and a release film <NUM> that is adhered on an exposed surface of the double-sided tape <NUM>.

Further, when the nanocrystalline ribbon sheet <NUM> is a two-layer structure, the double-sided tape is inserted in the intermediate portion of the two-layer structure.

Meanwhile, a thin ribbon made of a Fe-based nanocrystalline magnetic alloy can be used as the nanocrystalline ribbon sheet <NUM>.

An alloy satisfying the following Equation <NUM> is preferably used as the Fe-based nanocrystalline magnetic alloy.

Fe<NUM>-c-d-e-f-gAcDdEeSifBgZh     Equation <NUM>.

In Equation <NUM>, an element A is at least one element selected from Cu and Au, an element D is at least one element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ni, Co, and rare earth elements, an element E is at least one element selected from Mn, Al, Ga, Ge, In, Sn, and platinum group elements, an element Z is at least one element selected from C, N, and P, c, d, e, f, g, and h are numbers that satisfy the following relational expressions <NUM> ≤ c ≤ <NUM> at%, <NUM> ≤ d ≤ <NUM> at%, <NUM> ≤ e ≤ <NUM> at%, <NUM> ≤ f ≤ <NUM> at%, <NUM> ≤ g ≤ <NUM> at%, <NUM> ≤ f + g+ h ≤ <NUM> at%, respectively, and the alloy structure of an area ratio of <NUM>% or more is formed of the fine structure of the particle size of equal to or less than <NUM>.

In the aforementioned Equation <NUM>, the element A is used to enhance corrosion resistance of the alloy, to prevent coarsening of crystal grains and at the same time, improve the magnetic properties such as the iron loss and the permeability of the alloy. When the content of the element A is too small, it is difficult to obtain the effect of suppressing coarsening of crystal grains. Conversely, when the content of the element A is excessively large, the magnetic properties are degraded. Thus, it is preferable that the content of the element A is in the range from <NUM> to <NUM> at%. The element D is an element that is effective for the uniformity of the crystal grain diameter, the reduction of magnetostriction, etc. It is preferable that the content of the element D is in the range from <NUM> to <NUM> at%.

The element E is an element that is effective for the soft magnetic properties of the alloy and improvement of corrosion resistance of the alloy. The content of the element E is preferably not more than <NUM> at%. The elements Si and B are elements that make the alloy to become amorphous at the time of producing the magnetic sheet. It is preferable that the content of the element Si is in the range from <NUM> to <NUM> at%, and it is preferable that the content of the element B is in the range from <NUM> to <NUM> at%. In addition, it may include the element Z as an element that makes the alloy to become amorphous, other than Si and B. In that case, the total content of the elements Si, B and Z is preferably in the range of <NUM> to <NUM> at%. It is preferable to implement the microcrystalline structure that crystal grains whose grain diameters are in the range of <NUM> to <NUM> nmexist in the range of <NUM> to <NUM>% as an area ratio in the alloy structure.

Further, a Fe-Si-B-Cu-Nb alloy can be used as a Fe-based nanocrystalline magnetic alloy that is used in the nanocrystalline ribbon sheet <NUM>, and in this case, it is preferable that the content of Fe is <NUM>-<NUM> at%, the content of the sum of Si and B is <NUM>-<NUM> at%, and the content of the sum of Cu and Nb is <NUM>-<NUM> at%. An amorphous alloy that is obtained by producing such a composition range in the form of a ribbon can be easily precipitated into nanocrystalline grains by a thermal treatment to be described later.

As shown in <FIG>, a magnetic field shield sheet <NUM> according to a first example of the present invention has a structure that one nanocrystalline ribbon sheet <NUM> is used in which a protective film <NUM> is bonded on one side of the nanocrystalline ribbon sheet <NUM>, and a release film <NUM> is bonded via a double-sided tape <NUM> on the other side of the nanocrystalline ribbon sheet <NUM>.

In the case of a large display having a big area than a smartphone, for example, a portable terminal device with a width of <NUM>, two magnetic field shield sheets <NUM> according to the first example of the present invention each sheet having a <NUM> width are butted or overlapped with each other in the longitudinal direction. Since currently produced amorphous ribbons are typically about <NUM> wide, two sheets are butted in the longitudinal direction, to thus cover the magnetic field shield sheet <NUM> for the portable terminal device having a width of <NUM>.

Furthermore, in the case of constituting a magnetic field shield sheet 10b for a portable terminal device with a width of <NUM> like the second example as shown in <FIG>, first and second nanocrystalline ribbon sheets <NUM> and <NUM> are connected in a butting or overlapping manner in a first layer as two magnetic sheets, a wide-width double-sided tape 3a is stacked over the first layer, and third and fourth nanocrystalline ribbon sheets <NUM> and <NUM> are connected in a butting or overlapping manner so as to cross in a direction perpendicular to the first and second nanocrystalline ribbon sheets <NUM> and <NUM>. In this manner, the magnetic field shield sheet 10b for the wide-width portable terminal device can be configured.

As described above, a number of nanocrystalline ribbon sheets <NUM>-<NUM> are stacked and used, the double-sided tape 3a is inserted between a plurality of nanocrystalline ribbon sheets <NUM>-<NUM> as in the second example of the present invention.

As shown in <FIG>, the protective film <NUM> may be implemented by using a base member <NUM> including a polyethylene terephthalate (PET) film, a polyimide film, a polyester film, polyphenylene sulfade (PPS) film, a polypropylene (PP) film, or a fluorine resin-based film such as poly terephthalate (PTFE). A first adhesive layer <NUM> is attached to one side of the protective film <NUM>. When the protection film <NUM> is attached on one side of the nanocrystalline ribbon sheet <NUM>, or <NUM>-<NUM>, a release film 4a attached on the other surface of the first adhesive layer <NUM> to protect the first adhesive layer <NUM> is removed and then the protection film <NUM> is attached on one side of the nanocrystalline ribbon sheet.

Further, the protective film <NUM> is <NUM> to <NUM>, in thickness, and it is preferably in the range of <NUM>-<NUM>, and it is more preferable to have a thickness of <NUM>.

Further, as shown in <FIG>, the double-sided tape <NUM>, 3a, or 3b is formed of a base member <NUM> made of a fluorine resin-based film, for example, a PET (Polyethylene Terephthalate) film, on both sides of which second and third adhesive layers <NUM> and <NUM> are formed. Release films <NUM> and 4b are attached on the outer surfaces of the second and third adhesive layers <NUM> and <NUM>, respectively, in order to protect the second and third adhesive layers <NUM> and <NUM>.

When the double-sided tape 3a or 3b is inserted between the nanocrystalline ribbon sheets <NUM>-<NUM> in order to interconnect the nanocrystalline ribbon sheets <NUM>-<NUM>, the release films <NUM> and 4b on both sides of the double-sided tape 3a or 3b are peeled off and removed. The double-sided tape 3b coupled to the exterior of the nanocrystalline ribbon sheets <NUM> and <NUM> at the lowermost portion of the stacked nanocrystalline ribbon sheets <NUM>-<NUM>, is made at a state where the release film <NUM> is attached in order to protect a third adhesive layer <NUM> exposed to the outside.

The double-sided tapes <NUM>, 3a and 3b may be a type of including a base member as described above, but may be a type of including no base member but being formed of only adhesive layers. In the case of the double-sided tapes 3a and 3b interposed between the nanocrystalline ribbon sheets <NUM>-<NUM>, it is preferable to use no-base type double-sided tapes in terms of a thinning process.

The adhesive layers <NUM>, <NUM>, and <NUM> that are used for the protective film <NUM> and the release film <NUM> may be implemented by using, for example, acrylic adhesives, but may be of course possibly implemented by using different types of adhesives.

The double-sided tapes <NUM>, 3a, and 3b may have <NUM>, <NUM>, <NUM> thick, preferably have a thickness of <NUM>.

As shown in <FIG>, the magnetic field shield sheet <NUM>, 10a, or 10b according to the embodiment of the present invention may be made into a rectangular shape in correspondence to a digitizer <NUM> of <FIG>, and has preferably a shape corresponding to a shape of a portion required for shielding a magnetic field.

One piece of the nanocrystalline ribbon sheet <NUM> that is used for the magnetic field shield sheet <NUM>, 10a or 10b may have a thickness of <NUM> to <NUM> for example. In this case, in consideration of a handling process after the heat treatment of the nanocrystalline ribbon sheet <NUM>, and a treatment process when two or more ribbons are overlapped, a thickness of the nanocrystalline ribbon sheet <NUM> is preferably set to be in the range of <NUM> to <NUM>. The thinner the thickness of the ribbon may become, a breakage phenomenon of the ribbon may occur due to even a little shock at the time of performing a handling process after the heat treatment. Especially, in the case that two pieces of ribbons are overlapped, the mating surface of the ribbons may become wrinkled due to the thin ribbons, to thereby cause handling difficulties.

Hereinafter, a method of manufacturing a magnetic field shield sheet <NUM> according to the embodiment of the present invention, will be described with reference to <FIG>.

First, an ultra-thin amorphous ribbon equal to or less than <NUM> made of a nanocrystalline alloy as a Fe-based amorphous ribbon, e.g., a Fe-Si-B-Cu-Nb alloy is prepared by a rapidly solidification process (RSP) due to melt spinning (S11), and is cut in a predetermined length to then be laminated in a sheet form (S12) so that post- processing after a heat treatment can be easily performed.

Then, the laminated amorphous ribbon sheet is heat treated at a temperature exceeding <NUM> up to <NUM> for <NUM> minutes to <NUM> hours thereby forming the nanocrystalline ribbon sheet <NUM> or <NUM>-<NUM> formed of nanocrystalline grains (S13).

The nanocrystalline ribbon sheet <NUM> or <NUM>-<NUM> is obtained through a method of making a nanocrystalline alloy in a ribbon or strip form, and heat treating the nanocrystalline alloy of the ribbon or strip form under a none-magnetic field circumstance, at a heat treatment temperature interval (Tp) exceeding <NUM> to <NUM> for <NUM> minutes to <NUM> hours, to thereby precipitate fine crystal grains. In this case, since content of Fe is more than <NUM> at%, if heat treatment is made in the air in view of the heat treatment atmosphere, oxidation is made to thereby cause an undesirable situation in terms of visual aspects. Thus, the heat treatment is preferably performed in a nitrogen atmosphere. However, even if the heat treatment is made under an oxidizing atmosphere, permeability of the nanocrystalline ribbon sheet has substantially no difference at the same temperature condition.

In the case that the heat treatment temperature is less than <NUM>, the nanocrystalline grains are not sufficiently produced and thus a desired permeability is not obtained. In addition, it takes a longer time for the heat treatment. Also, in a subsequent step of handling a flake treatment process, the magnetic sheet is not well flaked. In addition, in the case of exceeding <NUM>, the permeability is significantly lowered by an overheat treatment. Generally, when the heat treatment temperature is low, it takes a long time for the heat treatment. In contrast, when the heat treatment temperature is high, the heat treatment time is shortened.

Referring to <FIG>, when amorphous ribbon is heat treated, nanocrystalline grains will be generated from <NUM> during an increase of the heat treatment temperature, and a value of the inductance of the heat treated amorphous ribbon, i.e. the sheet increases according to an increase in temperature. When the temperature is in the range of <NUM> to <NUM>, the inductance value of the sheet is increased to the maximum. Thereafter, if the sheet is overheated up to <NUM> exceeding the temperature of <NUM> to <NUM>, the inductance value of the sheet is inversely proportional to the heat treatment temperature, to thus show abruptly reduced values. The amorphous ribbon exhibits the maximum inductance value between temperatures of <NUM> to <NUM> due to individual variations.

The permeability of the sheet is proportional to the inductance value. Thus, if overheating is made up to <NUM> exceeding the temperature of <NUM> to <NUM>, magnetic sheets having a desired magnetic permeability can be easily manufactured by using a point that represents the characteristics of linearly decreasing the inductance value of the sheet.

In addition, if the amorphous ribbon is overheated in an overheating treatment temperature interval (To) between <NUM> to <NUM>, embrittlement becomes strong. Thus, when a flake treatment process is executed in a subsequent step, the amorphous ribbon is easily flaked. Furthermore, since the overheating treatment temperature interval (To) is wide, and if the sheet is heat treated by using the wide overheating treatment temperature interval (To), the magnetic permeability of the shield sheet may be widely selected.

The permeability of the surface of the heat-treated sheet can be obtained by measuring the inductance value of the sheet under the conditions of <NUM> and <NUM> V in an LCR meter by using of a coil of <NUM>µH, and then converting the measured inductance value of the sheet into the permeability of the surface of the heat-treated sheet.

In the case of the polymeric sheet, the inductance value of <NUM>µH is obtained, and in the case of the heatless treatment Fe-based amorphous sheet, the inductance value of <NUM>µH is obtained.

Subsequently, a flake treatment process is performed with respect to one or two pieces of the heat treated nanocrystalline ribbon sheets <NUM>, at a state where a protective film <NUM> is attached on one side thereof, and a double-sided tape <NUM> attached with a release film <NUM> is attached on the other side thereof (S14).

In the case that the stacked nanocrystalline ribbon sheets <NUM>-<NUM> are stacked in a two-layer form, the double-sided tape 3a is inserted between the ribbon sheets <NUM>-<NUM>, to thus enable mutual adhesion of the ribbon sheets <NUM>-<NUM>.

The flake treatment process is executed by allowing the laminate sheet <NUM> that is obtained by sequentially stacking, for example, the protective film <NUM>, the nanocrystalline ribbon sheet <NUM>, the double-sided tape <NUM>, and the release film <NUM>, to pass through first and second flake devices <NUM> and <NUM> illustrated in <FIG> and <FIG>, to thereby separate the nanocrystalline ribbon sheet <NUM> into a number of fine pieces <NUM>. In this case, a plurality of the separated fine pieces <NUM> are maintained to keep a separated state by first and second adhesive layers <NUM> and <NUM> that are bonded to both sides of the nanocrystalline ribbon sheet <NUM> as shown in <FIG>.

For example, as shown in <FIG>, an available first flake device <NUM> may consist of a metal roller <NUM> on the outer surface of which a plurality of irregularities <NUM> are formed, and a rubber roller <NUM> that is disposed in opposition to the metal roller <NUM>. As shown in <FIG>, a second flake device <NUM> may be composed of a metal roller <NUM> on the outer surface of which a plurality of spherical balls <NUM> are mounted, and a rubber roller <NUM> that is disposed in opposition to the metal roller <NUM>.

Thus, when the laminate sheet <NUM> is passed through the first and second flake devices <NUM> and <NUM>, the nanocrystalline ribbon sheet <NUM> is separated into a number of the fine pieces <NUM> and gaps 20a are formed between the fine pieces <NUM>, as shown in <FIG>.

Since the fine pieces <NUM> of the nanocrystalline ribbon sheet <NUM> are formed to have a size of a range of several tens micrometers (µm) to <NUM> milimeters (mm), preferably, to have a size of a range of several hundred micrometers (µm) to <NUM> milimeters (mm), a demagnetizing field is made to increase to thereby remove a hysteresis loss and to thus heighten a uniformity of the permeability of the sheet.

Further, the flake treatment process of the nanocrystalline ribbon sheet <NUM> may reduce the surface area of the fine pieces <NUM> and prevent a heat generation problem caused by an eddy current that is produced by an alternating-current magnetic field.

The flake treated laminate sheet <NUM> has the gaps 20a between fine pieces <NUM>. Thus, when the water is penetrated into the gaps 20a, the nanocrystalline ribbon sheet is oxidized and the appearance of the nanocrystalline ribbon sheet is poor and the shield performance is degraded.

Further, in the case that only a flake treatment process is performed, the fine pieces <NUM> are in contact with each other along the flow of the fine pieces <NUM>, to accordingly increase the size of the fine pieces <NUM> and to thus cause a problem that the eddy-current loss increases.

Furthermore, the flake treated laminate sheet <NUM> may have non-uniformity caused on the surface of the sheet during performing the flake treatment process, and stabilization of the flake treated ribbon is needed.

Thus, the flake treated laminate sheet <NUM> undergoes a laminating process for flattening, slimming, and stabilization of the sheet <NUM>, while simultaneously filling the adhesive into the gaps 20a of the fine pieces <NUM> (S15). As a result, water penetration is prevented, and at the same time all sides of the fine pieces <NUM> are surrounded by the adhesive, to thereby separate the fine pieces <NUM> from one another and reduce the eddy current.

As shown in <FIG>, a laminating device <NUM> for the laminating process may employ a roll press type including a first pressing roller <NUM> and a second pressing roller <NUM> that is disposed at a predetermined distance from the first pressing roller <NUM>, between which the flake treated laminate sheet <NUM> passes. As shown in <FIG>, a laminating device <NUM> for the laminating process may employ a hydraulic press type including a lower pressing member <NUM> and an upper pressing member <NUM> that is vertically movably disposed on the upper side of the lower pressing member <NUM>.

When the flake treated laminate sheet <NUM> is heated at room temperature or at a temperature of <NUM> to <NUM>, and then is passed through the laminating device <NUM> or <NUM>, a first adhesive layer <NUM> of the protective film <NUM> is pressed, while some of the adhesive of the first adhesive layer <NUM> are introduced into the gaps 20a to seal the gaps 20a. Simultaneously, the double-sided tape <NUM> is pressed, while some of the adhesive of the second adhesive layer <NUM> are introduced into the gaps 20a to seal the gaps 20a.

Here, the first adhesive layer <NUM> and the second adhesive layer <NUM> may be formed by using an adhesive that can be deformed at the time of being pressed at room temperature, or may be formed by using a thermoplastic adhesive that can be thermally deformed by applied heat.

In addition, the first adhesive layer <NUM> and the second adhesive layer <NUM> preferably have a thickness of at least <NUM>% when compared to the thickness of the nanocrystalline ribbon so as to sufficiently fill the gaps 20a between the fine pieces <NUM>.

Further, the interval between the first pressure roller <NUM> and the second pressure roller <NUM> and the interval between the upper pressing member <NUM> and the lower pressing member <NUM> when the upper pressing member <NUM> is in a lowered state, are preferably formed of a thickness of <NUM>% or less when compared to the thickness of the laminate sheet <NUM>, so that the adhesives of the first adhesive layer <NUM> and the second adhesive layer <NUM> can be introduced into the gaps 20a.

Any device of performing the pressing of the laminate sheets <NUM> and <NUM> and the flake treatment process, can be used in the present invention.

As shown in <FIG>, when the laminating process is completed, an electromagnetic wave absorbing sheet <NUM> according to the present invention may have a structure that the first adhesive layer <NUM> and the second adhesive layer <NUM> partially fill the gaps 20a between the fine pieces <NUM> at a state where the nanocrystalline ribbon sheet <NUM> is separated into the fine pieces <NUM>, to thereby prevent the oxidation and the flow of the nanocrystalline ribbon sheet <NUM>.

Finally, the magnetic field shield sheet <NUM> or 10b having undergone the laminating process is stamped into a rectangular shape of the size corresponding to a digitizer <NUM> of <FIG> so as to be produced into products (S16).

In the embodiment, it has been described with respect to the case that a sheet of the protective film <NUM> is adhered to one side of the magnetic sheet <NUM> and then the flake treatment process and the laminating process are executed, but the protective film <NUM> may be damaged by the flake treatment process. Thus, preferably, a temporary protective film for protecting the protective film <NUM> is attached on top of the protective film <NUM> before performing a treatment process, and then the temporary protective film on the surface of the magnetic sheet <NUM> is peeled off and removed after completion of the treatment process.

A humidity test was conducted for <NUM> hours at temperature of <NUM> and humidity of <NUM>% with respect to the magnetic field shield sheet <NUM> obtained in accordance with the invention and the laminate sheet <NUM> that has undergone the flake process but does not pass through the lamination process.

As a result, as shown in <FIG>, in the case of the laminate sheet <NUM> where only the flake-treatment was processed, it can be seen that water is penetrated into the gaps between fine pieces when the amorphous ribbon has been separated into a large number of fine pieces and then the amorphous ribbon is oxidized, and thus the appearance of the amorphous ribbon was changed. However, it can be seen that the magnetic field shield sheet <NUM> in accordance with the present invention shows the appearance that does not change as shown in <FIG>.

The magnetic field shield sheet 10b of the two-layer structure illustrated in <FIG> according to the second example of the present invention is configured by using the same nanocrystalline ribbon sheets <NUM>-<NUM> as the magnetic sheets, but the magnetic field shield sheet according to the present invention may be configured by using a hybrid type thin magnetic sheet made of different materials as in the case of the third example of the present invention illustrated in <FIG>.

As shown in <FIG>, a thin film magnetic sheet <NUM> according to the third example of the present invention can be configured in a hybrid form in which a bonding layer 35c is inserted and combined between a first magnetic sheet 35a of a high permeability and a second magnetic sheet 35b of a permeability lower than that of the first magnetic sheet 35a.

A nanocrystalline ribbon sheet consisting of the above-described nanocrystalline alloy or nanocrystalline alloy, a permalloy sheet having an excellent soft magnetic characteristic, or a MPP (Moly Permalloy Powder) sheet can be used as the first magnetic sheet 35a.

The second magnetic sheet 35b may be formed of a polymer sheet consisting of a magnetic powder of a high permeability such as an amorphous alloy powder, soft magnetic powder, or a Sendust, and a resin.

In this case, the amorphous alloy powder has a composition selected from the group consisting of for example, Fe-Si-B, Fe-Si-B-Cu-Nb, Fe-Zr-B and Co-Fe-Si-B, and preferably is formed of an amorphous alloy powder comprising one or more amorphous alloys.

Further, in the case that both a near field communications (NFC) function and a wireless charging function are employed in a portable terminal, the hybrid-type thin film magnetic sheet <NUM> is formed by using an amorphous ribbon sheet and a ferrite sheet with low frequency dependence that are laminated and stacked one over another, as the first and second magnetic sheets 35a and 35b, as shown in <FIG>. Accordingly, it is possible to solve both the near field communications (NFC) function and the wireless charging function by using the ferrite sheet for the magnetic field shield for the NFC and by using the amorphous ribbon sheet for the digitizer.

Further, the hybrid-type thin film magnetic sheet <NUM> may be formed by using a certain area of a nanocrystalline ribbon sheet at a center of the hybrid-type thin film magnetic sheet <NUM>, as a first magnetic sheet 36a, and by combining a second annular magnetic sheet 36b that surrounds the whole of the first magnetic sheet 36a on the outside of the first magnetic sheet 36a into a polymer sheet or a ferrite loop, as shown in <FIG>. That is, the polymer sheet or the ferrite having a relatively smaller permeability than the nanocrystalline ribbon sheet is formed in a loop form and is arranged in the outer block of the nanocrystalline ribbon sheet. As a result, the present invention can shield the magnetic field applied to the digitizer, while minimizing an influence upon the geomagnetic sensor <NUM>.

In addition, referring to <FIG>, the hybrid type thin magnetic sheet <NUM> according to the third example of the present invention is configured by including first and the second magnetic sheets 37a and 37b of different areas. The first magnetic sheet 37a is formed of a nanocrystalline ribbon sheet of a larger area than the second magnetic sheet 37b, and the second magnetic sheet 37b is formed of a magnetic sheet having a higher permeability than the nanocrystalline ribbon sheet on one side of the first magnetic sheet 37a, for example, a heatless treatment Fe-based amorphous sheet with a width of about <NUM>-<NUM>. That is, the first magnetic sheet 37a and the second magnetic sheet 37b are combined in a hybrid form, to thus form the hybrid type thin magnetic sheet <NUM>.

In the case of forming the hybrid type thin magnetic sheet <NUM>, the second magnetic sheet 37b may be overlapped with the first magnetic sheet 37a, or may be partially overlapped with the first magnetic sheet 37a and extended from one end of the first magnetic sheet 37a. Otherwise, the second magnetic sheet 37b may be extended on a flat plane from one end of the first magnetic sheet 37a. In the case that the magnetic field shield sheet using the hybrid type thin magnetic sheet <NUM> is applied to the portable terminal device <NUM>, the second magnetic sheet 37b consisting of the Fe-based amorphous sheet is mounted to be disposed at a remote place from the geomagnetic sensor <NUM> disposed in a main circuit board <NUM> of <FIG>.

The second magnetic sheet 37b consisting of a high permeability Fe-based amorphous sheet is used in a range capable of minimizing an influence on the geomagnetic sensor <NUM>, and the high permeability magnetic field shield sheet plays a role of assisting to absorb electromagnetic waves required to perform the digitizer function, that is, improves sensitivity of the electronic pen by increasing a transfer rate of a magnetic flux.

Meanwhile, the hybrid type thin magnetic sheets <NUM> according to the third example of the present invention shown in <FIG> employs the second magnetic sheet 37b having the higher permeability than the first magnetic sheet 37a. However, the second magnetic sheet 37b has the lower permeability than the first magnetic sheet 37a.

That is, the first magnetic sheet 37a is composed of a nanocrystalline ribbon sheet, and the second magnetic sheet 37b is composed of a polymer sheet. The second magnetic sheet 37b having a low magnetic permeability is mounted to be disposed at a near place from the geomagnetic sensor <NUM> disposed in the main circuit board <NUM> of <FIG>. As a result, the present invention can shield the magnetic field applied to the digitizer, while minimizing an influence upon the geomagnetic sensor <NUM>.

Meanwhile, <FIG> shows a shield sheet having a function of shielding an electromagnetic wave according to a fourth example of the present invention.

The shield sheet 10c according to the fourth example of the present invention has a structure that a conductive sheet <NUM> made of a Cu or Al foil having an excellent conductivity is bonded on one side of the magnetic field shield sheet <NUM> according to the first example of the present invention, by using a double-sided tape or adhesive, so as to provide an additional function of shielding the electromagnetic wave. It is suitable that the conductive sheet <NUM> has a thickness of <NUM> to <NUM>, preferably, a thickness of <NUM> to <NUM>.

Further, the conductive sheet <NUM> can be possibly formed of a thin film metal layer made of one selected from Cu, Ni, Ag, Al, Au, Sn, Zn, Mn or a combination thereof, by a sputtering method, other than the conductive sheet <NUM> made in the form of a foil.

The shield sheet 10c having the function of shielding the electromagnetic wave, can be used to block an electromagnetic wave generated from a main body of a notebook computer such as a laptop computer from influencing a digitizer, in the case that a digitizer function is provided for the notebook computer from which the electromagnetic wave, for example, such as power source noise is severely generated.

In this case, the shield sheet 10c according to the fourth example of the present invention is attached to the back surface of a digitizer panel (PCB) throughout the double-sided tape <NUM> so that the conductor sheet <NUM> is exposed toward the main circuit board.

Meanwhile, a structure that the magnetic field shield sheet according to the present invention is applied to a portable terminal device having a digitizer function will be described below with reference to <FIG>.

<FIG> is a schematic exploded perspective view of the structure that a magnetic field shield sheet according to the present invention is applied to a portable terminal device having a digitizer function.

Referring to <FIG>, a portable terminal device <NUM> according to the present invention includes a touch screen panel <NUM>, a display panel <NUM>, a digitizer panel <NUM>, a magnetic field shield sheet <NUM>, a bracket <NUM>, a main circuit board <NUM>, and a rear cover <NUM> that are sequentially engaged, and an electronic pen <NUM> that receives power from the portable terminal device <NUM> in a non-contact manner to then be activated.

The portable terminal device <NUM> includes an integrated touch panel <NUM> disposed on the whole surface of an LCD or AMOLED type display panel <NUM>, on a top surface of the portable terminal device <NUM>, in order to act as an interface between the portable terminal device <NUM> and a user. The touch screen panel, for example, may be implemented in an 'On-Cell' manner just above the AMOLED display in a deposition form.

In order to implement the portable terminal device <NUM> having a digitizer function, the electronic pen <NUM> is configured to have a coil-shaped antenna and circuit elements for wireless communications therein to send and receive information to and from the portable terminal device <NUM> via wireless communications, to thereby receive power in a non-contact manner to thus drive the circuit elements.

To this end, the electronic pen <NUM> receives an alternating-current (AC) magnetic field of a band of <NUM> to <NUM> generated in the portable terminal device <NUM> so that power is wirelessly transmitted to the electronic pen <NUM>, and thus the internal circuit elements are driven, by employing a wireless charge function by an electromagnetic induction coupling method, and performs wireless communications between the digitizer panel <NUM> and the electronic pen <NUM> by using frequencies above <NUM>.

Features of the electronic pen are implemented by the digitizer panel <NUM> disposed on the lower side of the touch screen panel <NUM> and the display panel <NUM>. The digitizer panel <NUM> is formed of a thin metallic film. If electricity flows through the digitizer panel <NUM>, the electromagnetic field is created. An ultra-miniature antenna coil for generating an alternating-current (AC) magnetic field is provided at the tip end portion of the electronic pen <NUM>.

When the tip end portion of the pen <NUM> is made to approach the touch screen panel <NUM>, In the case of using the digitizer function, an electromagnetic induction phenomenon occurs while the electromagnetic field that has already been formed on the digitizer panel <NUM> disposed below the touch screen panel <NUM> and the display panel <NUM> is transformed. Such a transformation of the electromagnetic field is detected by a sensor (not shown) disposed on one side edge of the digitizer panel <NUM>, to thus recognize X and Y coordinates and the behavior of the pen.

In order to use the digitizer function using the electromagnetic induction phenomenon, it is necessary to shield electromagnetic fields generated from various components of a main circuit board <NUM> from influencing upon the digitizer panel <NUM>. For this purpose, a magnetic field shield sheet <NUM> is inserted between the digitizer panel <NUM> and the main circuit board <NUM>.

The magnetic field shield sheet <NUM> can be in close contact with the rear surface of the digitizer panel <NUM>, by using a double-sided tape, or can detachably coupled to the rear surface of the digitizer panel <NUM>, by using a separate fixing bracket <NUM>.

That is, as shown in <FIG>, in the case of a method of attaching the magnetic field shield sheet <NUM> on the rear surface of the digitizer panel <NUM>, the release film <NUM> is removed from the lower portion of the magnetic field shield sheet <NUM> and the double-sided tape <NUM> exposed from the lower portion of the magnetic field shield sheet <NUM> is attached on the rear surface of the digitizer panel <NUM>.

Further, as shown in <FIG>, instead of a method of attaching the magnetic field shield sheet <NUM> on the rear surface of the digitizer panel <NUM>, an alternative double-sided tape disposed on top of a protective film <NUM> of the magnetic field shield sheet <NUM> is attached on the rear surface of the digitizer panel <NUM>, and the release film <NUM> is removed from the lower portion of the magnetic field shield sheet <NUM> and a finishing material (not shown) may be attached to an adhesive layer <NUM> of the double-sided tape <NUM> exposed from the lower portion of the magnetic field shield sheet <NUM>.

Meanwhile, for implementing functions such as navigation or augmented reality, the portable terminal device is provided with the geomagnetic sensor <NUM> disposed on one corner of the main circuit board <NUM>.

The magnetic field shield sheet <NUM> is made in size corresponding to the digitizer panel <NUM> so as not to affect the digitizer function. In this case, the magnetic field shield sheet <NUM> is formed slightly smaller than the size of the main circuit board <NUM>, and thus it is desirable to maintain spacing of at least <NUM> between the magnetic field shield sheet <NUM> and the geomagnetic sensor <NUM> inside the portable terminal device.

Even when the magnetic field shield sheet <NUM> according to the invention is made to lie adjacent to the geomagnetic sensor <NUM> as described above, and to be used in the portable terminal device together with the geomagnetic sensor <NUM>, an influence upon the geomagnetic sensor <NUM> is minimized.

As described above, the magnetic field shield sheet <NUM> according to the present invention includes at least one layer nanocrystalline ribbon sheet made of a nanocrystalline microstructure and flake-treated so as to be separated and/or cracked into a plurality of fine pieces, to thereby maximize a magnetic permeability for a magnetic field shield function, and simultaneously reduce a surface area of the ribbon by a flake treatment process. As a result, a demagnetizing field increases and thus magnetic saturation is not achieved.

Further, the nanocrystalline ribbon sheet <NUM> is flake-treated to thereby reduce the surface area of the ribbon, and to thus block a heat generation problem due to the eddy currents generated by the alternating-current (AC) magnetic field.

Meanwhile, the magnetic field shield sheet employed in the portable terminal device is built in the portable terminal device in order to shield a vertical magnetic field applied along the direction perpendicular to the magnetic field shield sheet. However, the portable terminal device can be placed in a situation where a magnetic field that includes the geomagnetic field and is much higher than the geomagnetic field is applied from the side surfaces of the magnetic field shield sheet.

When a magnetic field is applied from the outside along one side surface of a magnetic field shield sheet in the case that the conventional Fe-based amorphous ribbon sheet is applied as the magnetic field shield sheet, the magnetic field passes through along the plane of the sheet and radiates toward the opposite side to the sheet to which the magnetic field has been input. As a result, the geomagnetic sensor <NUM> has a difference in the intensities of the sensitivities in X, Y, and Z directions, and causes a problem that an angular error occurs.

In contrast, since the nanocrystalline ribbon sheet <NUM> according to the present invention is separated and/or cracked into a large number of fine pieces <NUM> by a flake treatment process, even in the case that a magnetic field is applied from the outside along one side surface of the nanocrystalline ribbon sheet <NUM>, the magnetic field is attenuated while passing through the fine pieces <NUM>, and thus does not nearly radiate toward the opposite side to the sheet to which the magnetic field has been input.

As a result, when the magnetic field shield sheet <NUM> having the nanocrystalline ribbon sheet <NUM> according to the present invention is used in a portable terminal device <NUM>, even in the case that a magnetic field is applied along one side surface of the magnetic field shield sheet <NUM> from the outside, the geomagnetic sensor <NUM> is not nearly influenced by the magnetic field.

Meanwhile, when looking at the BH loop of the Fe-based amorphous ribbon sheet, i.e., the magnetic hysteresis loop, as shown in <FIG>, a value of a saturation field (Hs) that is the minimum magnetic field for obtaining the saturation induction of the magnetic field is about <NUM> A/m (<NUM>), which is lower than that of the geomagnetic field having a value of about <NUM>.

Therefore, the Fe-based amorphous ribbon sheet exhibits a magnetic hysteresis phenomenon even in the case that the geomagnetic field is changing. As a result, the geomagnetic sensor that is used in a portable terminal device in which a Fe-based amorphous ribbon sheet is applied, has a fatal disadvantage that the hysteresis correction due to the Fe-based amorphous ribbon sheet should be performed.

On the contrary, when looking at the magnetic hysteresis loop of the nanocrystalline ribbon sheet <NUM> that is used in the magnetic field shield sheet <NUM> according to the present invention, as shown in <FIG>, a value of the saturation magnetic field (Hs) is about <NUM> A/m (≒ <NUM>), which is substantially higher than that of the geomagnetic field having a value of about <NUM>.

Thus, even in the case that the geomagnetic field is changing, the nanocrystalline ribbon sheet <NUM> does not exhibit a hysteresis and changes in the initial magnetization curve. As a result, the geomagnetic sensor <NUM> that is mounted in the portable terminal device <NUM> in which the magnetic field shield sheet <NUM> according to the present invention is applied does not exhibit a hysteresis due to the nanocrystalline ribbon sheet <NUM>, and thus has advantages of easy azimuth correction and a higher accuracy, when compared with the case that the heatless treatment Fe-based amorphous ribbon sheet is applied as the magnetic field shield sheet.

That is, when using the magnetic field shield sheet according to the present invention, the geomagnetic sensor does not cause a hysteresis distortion problem but cause only distortions of azimuth and sensor sensitivity. These distortions can be solved via a correction, to thereby implement a distortion-free navigation function.

In addition, as described above, in the case that the high permeability magnetic field shield sheet <NUM> is included in the digitizer panel <NUM> of the portable terminal device <NUM>, the high permeability magnetic field shield sheet <NUM> blocks effects influencing upon the digitizer panel <NUM> due to the alternating-current (AC) magnetic field that is generated when the portable terminal device performs the wireless communications or additional features such as NFC (Near Field Communications) or RFID (Radio Frequency Identification), and at the same time plays a role of assisting the high permeability magnetic field shield sheet <NUM> to absorb electromagnetic waves required to perform a digitizer function, that is, increases a transfer rate of the magnetic flux, to thereby improve sensitivity of the electronic pen.

Hereinafter, embodiments of the present invention will be described in more detail. However, the following examples are nothing but illustrative of the present invention and the scope of the present invention is not limited thereto.

(Characteristics of a geomagnetic sensor when a heatless treatment Fe-based amorphous ribbon sheet is used as a magnetic field shield sheet).

In Comparative Example <NUM>, a heatless treatment Fe-based amorphous ribbon sheet of <NUM> µ m thick was used as a magnetic sheet, and a protective film and a double-sided tape each of <NUM> µ m thick were attached on both sides of the heatless treatment Fe-based amorphous ribbon sheet, to thereby use the heatless treatment Fe-based amorphous ribbon sheet having an inductance value <NUM>µH as a magnetic field shield sheet in a portable terminal device having a digitizer function. Then, operating characteristics of a geomagnetic sensor were measured and shown in <FIG> and <FIG>.

<FIG> is a graph comparatively illustrating angular errors of five geomagnetic sensors in the case of using a heatless treatment Fe-based amorphous ribbon sheet of Comparative Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, in which the angular errors of the five geomagnetic sensors were measured at intervals of <NUM> degrees from <NUM> degrees to <NUM> degrees, to thereby show a degree of distortion of the azimuth of the geomagnetic sensor with respect to each of the measured azimuths of the five geomagnetic sensors.

<FIG> is a graph illustrating angular errors of a geomagnetic sensor that changes in accordance with the rotating directions of the geomagnetic sensor, in the case of using a heatless treatment Fe-based amorphous ribbon sheet of Comparative Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, in which the angular errors of the geomagnetic sensor were measured at intervals of <NUM> degrees from <NUM> degrees to <NUM> degrees while rotating the geomagnetic sensor in the right direction (the solid line) and in the left direction (the dotted line), respectively, to thereby show a degree of distortion of the azimuth of the geomagnetic sensor with respect to each of the measured azimuths of the geomagnetic sensor.

Referring to <FIG>, when the heatless treatment Fe-based amorphous ribbon sheet of Comparative Example <NUM> was used as the magnetic field shield sheet, it can be seen that the angular errors of about <NUM> degrees were generated in the characteristics of some of the geomagnetic sensors and functions of some of the geomagnetic sensors were lost. Referring to <FIG>, it can be seen that a great hysteresis phenomenon occurred according to the direction of rotation, an offset (that is a degree where a circle is beyond the origin point) was distorted by approximately <NUM>% in the Y-axis direction due to the influence of the heatless treatment Fe-based amorphous ribbon sheet, and a sensitivity of the X-axis was also smaller by about <NUM>% in comparison with the Y-axis, due to the influence of the magnetic hysteresis of the heatless treatment Fe-based amorphous ribbon sheet.

(Characteristics of a geomagnetic sensor when a polymer sheet is used as a magnetic field shield sheet).

In Comparative Example <NUM>, a high permeability Sendust alloy (i.e., a Fe-Si-Al alloy) powder was mixed with a polymer material that acts as a binder, to thereby prepare a Sendust sheet of <NUM> thick having an inductance value <NUM>µH as a polymeric sheet, and then a protective film and a double-sided tape each of <NUM> thick were attached on both sides of the polymeric sheet. Thereafter, when the prepared sheet was used as a magnetic field shield sheet in a portable terminal device having a digitizer function, operating characteristics of a geomagnetic sensor were measured and shown in <FIG> and <FIG>.

<FIG> is a graph comparatively illustrating angular errors of five geomagnetic sensors in the case of using a Sendust sheet of Comparative Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, and <FIG> is a graph illustrating angular errors of a geomagnetic sensor that changes in accordance with the rotating directions of the geomagnetic sensor, in the case of using a Sendust sheet of Comparative Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, in which the angular errors were measured in the same manner as that of Comparative Example <NUM>.

Referring to <FIG>, when the Sendust sheet of Comparative Example <NUM> was used as the magnetic field shield sheet, it can be seen that the angular errors of about <NUM> degrees were generated in the characteristics of some of the geomagnetic sensors and accuracies of some of the geomagnetic sensors were a little reduced. Referring to <FIG>, it can be seen that a very small hysteresis phenomenon occurred according to the direction of rotation, an offset was distorted by approximately <NUM>% in the Y-axis direction due to the influence of the Sendust sheet, and a sensitivity of the Y-axis was also smaller by about <NUM>% in comparison with the X-axis, due to the influence of the magnetic hysteresis of the Sendust sheet.

(Characteristics of a geomagnetic sensor when a nanocrystalline ribbon sheet is used as a magnetic field shield sheet).

In Example <NUM>, a nanocrystalline ribbon sheet of <NUM> µ m thick and having an inductance value is <NUM>µH was used as a magnetic sheet, and a protective film and a double-sided tape each of <NUM> µ m thick were attached on both sides of the nanocrystalline ribbon sheet, to then use the nanocrystalline ribbon sheet as a magnetic field shield sheet in a portable terminal device having a digitizer function, through flake and laminate processes. Then, operating characteristics of a geomagnetic sensor were measured and shown in <FIG> and <FIG>.

<FIG> is a graph comparatively illustrating angular errors of five geomagnetic sensors in the case of using a nanocrystalline ribbon sheet of Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, and <FIG> is a graph illustrating angular errors of a geomagnetic sensor that changes in accordance with the rotating directions of the geomagnetic sensor, in the case of using a nanocrystalline ribbon sheet of Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, in which the angular errors were measured in the same manner as that of Comparative Example <NUM>.

Referring to <FIG>, when the nanocrystalline ribbon sheet of Example <NUM> was used as the magnetic field shield sheet, and distortions of the five geomagnetic sensors were measured, it can be seen that the angular errors of about <NUM> degrees were generated in the characteristics of some of the geomagnetic sensors and accuracies of some of the geomagnetic sensors were a little reduced. Referring to <FIG>, it can be seen that a very small hysteresis phenomenon occurred according to the direction of rotation of the nanocrystalline ribbon sheet of Example <NUM>, an offset was distorted by approximately <NUM>% in the Y-axis direction due to the small influence of the nanocrystalline ribbon sheet, and a sensitivity of the X-axis was also smaller by about <NUM>% in comparison with the Y-axis, due to the small influence of the magnetic hysteresis of the nanocrystalline ribbon sheet.

In Example <NUM>, in the same manner as in Example <NUM>, a nanocrystalline ribbon sheet of <NUM> thick but having an inductance value of <NUM>µH was used as magnetic sheets, and a protective film and a double-sided tape each of <NUM> thick were attached on both sides of each of the nanocrystalline ribbon sheets, to then use the nanocrystalline ribbon sheet as magnetic field shield sheet in portable terminal devices having digitizer functions, through flake and laminate processes. Then, operating characteristics of a geomagnetic sensor were measured and shown in <FIG> and <FIG>.

<FIG> is a graph comparatively illustrating angular errors of five geomagnetic sensors in the case of using a nanocrystalline ribbon sheet of Example <NUM> whose inductance value is <NUM>µH, as the magnetic field shield sheet, and <FIG> is a graph illustrating angular errors of a geomagnetic sensor that changes in accordance with the rotating directions of the geomagnetic sensor, in the case of using a nanocrystalline ribbon sheet of Example <NUM> whose inductance values is <NUM>µH, as the magnetic field shield sheet.

When distortions of the five geomagnetic sensors were measured, it can be seen that the angular errors of about <NUM> degrees were generated in the characteristics of some of the geomagnetic sensors as shown in <FIG> in Example <NUM>, and accuracies of some of the geomagnetic sensors were excellent.

When looking at a hysteresis that changes in accordance with the rotating directions of the geomagnetic sensor, in the case of using the nanocrystalline ribbon sheet of Example <NUM>, it can be seen that a very small hysteresis phenomenon occurred, an offset was distorted by approximately <NUM>% in the Y-axis direction due to the small influence of the sheet, and a sensitivity was also smaller by about <NUM>% or less between the X-axis and the Y-axis, due to the small influence of the sheet, in Example <NUM>, as shown in <FIG>.

Accordingly, when the angular errors of the geomagnetic sensors as well as the hysteresis that changes according to the rotation direction of the geomagnetic sensor are compared with those of Comparative Examples having the same inductance value as Examples of the present invention, in the case of using the nanocrystalline ribbon sheet according to Examples of the present invention, it appeared that the sheets of the present invention were excellent in terms of all the hysteresis, offset and sensitivity.

In the case that the nanocrystalline ribbon sheet according to the present invention is configured by employing a sheet of an inductance value (permeability) of <NUM>µH that is a little smaller than the heatless treatment Fe-based amorphous ribbon sheet of Comparative Example <NUM>, the geomagnetic sensor was not nearly influenced. As a result, the nanocrystalline ribbon sheets having inductance values in the range of <NUM>µH to <NUM>µH do not almost cause angular errors to occur in geomagnetic sensors, so as to be used immediately without correction of an algorithm.

Further, it was investigated whether an electronic pen was activated in a certain distance from a display surface (that is, reinforced glass) of a portable terminal device with respect to Examples <NUM> and <NUM> and Comparative Examples <NUM> and <NUM>, and the results are shown in Table <NUM>.

The above experiments were conducted at the states where the magnetic field shield sheets of Examples <NUM> and <NUM> were used instead of a polymer sheet in a digitizer that was implemented by using the polymer sheet having an inductance value of <NUM>µH.

As described above, when the nanocrystalline ribbon sheet is used as a magnetic field shield sheet in the portable terminal device having a digitizer function, it can be seen that sensitivity of a signal that an electronic pen transmits is increased according to an increase of an inductance (that is, permeability) in the nanocrystalline ribbon sheet, and the electronic pen is activated in a non-contact state, that is, performance of the electronic pen is improved.

In the present invention, the electronic pen can be made active in the non-contact state with respect to the glass substrate of the display, to thereby improve durability of the display and the electronic pen, and to thus be able to develop a different function by using a digitizer function of a non-contact manner.

In order to see frequency characteristics with respect to a permeability of a magnetic field shield sheet that is implemented by using a nanocrystalline ribbon sheet according to the present invention, the inductance values of the sheet were measured by using a coil having an inductance value (Ls) of <NUM>µH, while changing frequencies from <NUM> to <NUM> under the condition of AC 1V in an LCR meter that is a piece of electronic test equipment used to measure the inductance (L), capacitance (C), and resistance (R) of a component, and thus the measured results are shown in <FIG>.

Referring to <FIG>, regarding nanocrystalline ribbon sheets having inductance values of <NUM>µH and <NUM>µH that are respectively used in the magnetic field shield sheets of the present invention (Examples <NUM> and <NUM>); a heatless treatment Fe-based amorphous ribbon sheet of <NUM>µH (Comparative Example <NUM>); a metal-powder sheet of a permeability of <NUM> (an inductance value of <NUM>µH) (M-P 100u); a metal-powder sheet of a permeability of <NUM> (an inductance value of <NUM>µH) (M-P 130u); and a metal-powder sheet of a permeability of <NUM> (an inductance value of <NUM>µH) (M-P 150u), the inductance value (Ls) of each sheet was measured according to the change in frequency. As a result, in the case of the Fe-based amorphous ribbon sheet (Comparative Example <NUM>), dependence on frequencies in the range of <NUM> to <NUM> appears considerably large. However, in the case of the nanocrystalline ribbon sheets (Examples <NUM> and <NUM>), dependence on frequencies in the range of <NUM> to <NUM> is not nearly present to thus exhibit identical permeability properties. In addition, a nanocrystalline ribbon sheet having an inductance value of <NUM>µH (Example <NUM>) also exhibits a much higher permeability characteristic than the metal-powder sheet of a permeability of <NUM> (an inductance value of <NUM>µH) (M-P 150u).

Therefore, in the case of using the nanocrystalline ribbon sheets according to the present invention, permeability characteristics become good and dependence on frequencies in the low frequency range is not nearly present. The nanocrystalline ribbon sheets according to the present invention have good characteristics as shield sheets for the digitizer.

In the present invention, nanocrystalline ribbon sheets each having a nanocrystalline microstructure are stacked and used by heat treatment of amorphous alloy ribbons or strips, to thus maximize the magnetic permeability for a magnetic field shielding function, and have a value of a saturation magnetic field (Hs) higher than the geomagnetic field, through a flake treatment process, and to thereby block magnetic saturation.

As a result, the nanocrystalline ribbon sheet <NUM> according to the present invention does not exhibit a hysteresis even in the case of a change in the geomagnetic field, and changes in the initial magnetization curve. Accordingly, when a magnetic field shield sheet <NUM> employing the nanocrystalline ribbon sheet <NUM> is used as the magnetic field shield sheet for the digitizer, the geomagnetic sensor <NUM> does not generate azimuth errors caused by the hysteresis of the nanocrystalline ribbon sheet, and thus can minimize hysteresis distortion problems of the geomagnetic sensor <NUM>.

In addition, the inventive nanocrystalline ribbon sheet <NUM> is flake-treated and thus significantly reduces the distortion phenomenon of the geomagnetic sensor according to an external magnetic field. As a result, even the sheets having the same inductance values of <NUM>µH but having not been flake-treated generate the azimuth errors of about <NUM> degrees. However, the sheets having been flake-treated generate the azimuth errors of about <NUM> degrees or less and do not affect the large impact on the geomagnetic sensors.

Accordingly, when the magnetic field shield sheet <NUM> employing the nanocrystalline ribbon sheet <NUM> according to the present invention is compared with the magnetic field shield sheet employing the conventional heatless treatment Fe-based amorphous ribbon sheet, the present invention has advantages of easy azimuth correction and a higher accuracy. In addition, when compared with the polymer sheet consisting of the magnetic powder and the binder, the present invention has a higher magnetic permeability, and thus can implement a wireless electronic pen function of a high sensitivity.

In addition, the present invention sequentially performs a flake treatment process and a laminating process by using a roll-to-roll method, to thereby achieve a molding process for a sheet, to thus maintain original thickness of the sheet and to thus exhibit high productivity and inexpensive manufacturing costs.

Claim 1:
A magnetic field shield sheet (<NUM>) for a digitizer, the magnetic field shield sheet (<NUM>) comprising:
at least one layer thin magnetic sheet (<NUM>) made of a nanocrystalline alloy which is flake-treated so as to be separated into a plurality of fine pieces (<NUM>);
a protective film (<NUM>) that is adhered on one surface of the thin magnetic sheet (<NUM>) via a first adhesive layer (<NUM>) provided on one side of the protective film (<NUM>); and
a double-sided tape (<NUM>) that is adhered on the other surface of the thin magnetic sheet (<NUM>) via a second adhesive layer (<NUM>) provided on one side of the double-sided adhesive tape (<NUM>),
wherein the magnetic field shield sheet (<NUM>) has an inductance value measured according to the description in the range of <NUM>µH to <NUM>µH that is obtained by heat treating an amorphous ribbon sheet in a temperature range exceeding <NUM> up to <NUM>.