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`LG Electronics Ex. 1031
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`U.S. Patent
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`Jan. 6, 1998
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`Sheet 1 of 5
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`5,706,134
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`LGE_001098
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`LGE_001098
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`U.S. Patent
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`Jan. 6, 1993
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`Sheet 2 of 5
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`5,706,134
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`1{
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`Fig. 3A
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`LGE_001099
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`LGE_001099
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`U.S. Patent
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`Jan. 6, 1993
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`Sheet 3 of 5
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`5,706,134
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`B X1
`Fig. 4A
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`LGE_001100
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`LGE_001100
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`U.S. Patent
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`Jan. 6, 1998
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`Sheet 4 of 5
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`5,706,134
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`LGE_001101
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`LGE_001101
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`U.S. Patent
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`Jan. 6, 1998
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`Sheet 5 of 5
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`5,706,134
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`LGE_001102
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`
`1
`LIGHT-DIFFUSING SHEET MEMBER
`
`5,706,134
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`2
`
`This is a continuation of U.S. application Ser. No.
`07/954,304. filed Sep. 30, 1992. now abandoned.
`FIH.D AND BACKGROUND OF THE
`INVENTION
`
`The present invention relates to a light diffusing sheet
`member which uniformly dilfuses fight, and more particu-
`larly to a light diffusing sheet member for use as a light
`diifusing plate that uniformly diffuses light transmitted from
`a light source which is the back light of a liquid crystal panel
`in a liquid crystal display.
`In a prior art liquid crystal display 10 as shown in FIG. 6,
`light irradiated by a fluorescent tube 11, which is a back
`light, passes through a guide plate 12. ‘The fluorescent tube
`11 is provided on the backside of a liquid crystal panel. On
`the bottom face of the guide plate 12 is provided a reflecting
`portion which consists of a metal deposition layer, which is
`formed by deposition of a metal such as silver or aluminum.
`The light guided upwardly is uniformly diffused and passed
`by a diffusing plate 13 provided above the guide plate 12,
`and is then guided to a liquid crystal display unit 14 provided
`above the diffusing plate 13.
`Conventionally, the diffusing plate 13 comprises a light
`diffusing sheet member wherein a resin such as polycarbon-
`ate which is melted and extruded on tl1e surface of a base
`material is finished by means of a pressing and cooling roll
`(so-called mat roll) or the like having many fine concave and
`convex portions impressed on its surface so that the resin has
`fine concave and convex portions on its surface, or the resin
`is heated and pressurized by means of a pressing roll having
`many fine convex portions on its surface so that the resin has
`many fine concave and convex portions (embossed).
`(1) Japanese Utility Model Publication No. 2648111991
`discloses a light difiusing sheet member in which a light
`diffusing layer is aflixed to the surface of a polyester film or
`the like, the light diffusing layer containing light diffusing
`materials such as titanium oxide, calcium carbonate, talc,
`silica powder, glass beads and the like.
`(2) Japanese Unexamined Utility Model Publication No.
`11201/1991 discloses a light diffusing sheet member in
`which light is uniformly irradiated from a light source to the
`outside through a sheet body irrespective of the distance
`from the light source by means of a pattern display having
`a diiferenoe in the distribution of density caused by a minute
`material group for light reflection such as aluminum powder
`or silver powder which is provided on the light irradiation
`face of the sheet body on the light source side.
`However, the light diffusing sheet member used as a
`difl"using plate of a liquid crystal display according to the
`prior art has the following drawbacks.
`According to the light diffusing sheet member in publi-
`cation No. 26481/1991, a fight diffusing material is aflixed
`to the film surface so that uniform light diffusion cannot
`fully be performed.
`According to the light difiusing sheet member in publi-
`cation No. 11201/1991, it is necessary that the difference in
`distribution be set great when the distance from the light
`source is increased. Accordingly, the structure is compli-
`cated and costs are increased.
`
`In both of the above light diffusing sheet members, the
`luminance of the screen of a liquid crystal display portion is
`not suflicient. Consequently, it is hard or impossible to read
`characters, graphics and the like displayed on the screen,
`depending on the viewing angle.
`
`LGE_001103
`
`It is an object of the present invention to provide a light
`diffusing sheet member wherein light is uniformly diffused
`and more particularly to a light diffusing sheet member used
`as a diffusing plate which uniformly diffuses light transmit-
`ted from a light source in a liquid crystal display, so that the
`luminance of a screen of a light difl‘using plate liquid crystal
`display portion is sufiicient and a user can easily look at
`characters, graphics and the like displayed on the screen
`from diiferent angles.
`
`SUMMARY OF THE INVENTION
`
`The present invention has been made in consideration of
`the above-mentioned problems and object. and comprises a
`light diffusing sheet member characterized in that a light
`diffusing layer is formed on the surface of a base material
`sheet, the light diffusing layer being a synthetic resin layer
`having beads mixed therein.
`is transparent and the light
`The base material sheet
`diffusing layer is a transparent synthetic resin layer having
`transparent beads mixed therein.
`The light diffusing layer has beads mixed therein. the
`beads having dilferent sizes.
`The beads include particles buried in the synthetic resin
`layer and particles which at least partially project from the
`synthetic resin layer.
`The beads cover almost the entire surface of the base
`material sheet.
`
`25
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`30
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`A metal deposition layer is formed on the back of the base
`material sheet.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`35
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`45
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`55
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`The foregoing and other objects. features and advantages
`of the present invention will become more apparent upon a
`reading of the following detailed description and the
`drawings, wherein:
`FIG. 1(a) is a partially enlarged sectional view showing a
`light diffusing sheet member according to a first embodi-
`ment of the present invention;
`FIG. 1(b) is a blowup of a portion of FIG. 1(a);
`FIG. 2 (a) is a sectional View showing the light diffusing
`sheet member according to the first embodiment of the
`present invention;
`FIG. 2 (b) is a sectional view showing a light diffusing
`sheet member according to a second embodiment of the
`present invention;
`FIGS. 3 (a) and 3 (b) are sectional views showing
`variations of the light dilfusing sheet member in accordance
`with the present invention;
`FIG. 4 (a) is a partial sectional view illustrating the state
`of light diffusion performed by the light diifusing sheet
`member according to the first embodiment of the present
`invention;
`
`FIG. 4 (b) is a partial sectional view illustrating the state
`of light diffusion performed by the light ditfusing sheet
`member according to the second embodiment of the present
`invention;
`
`FIG. 5 is a perspective View showing an application of the
`light diffusing sheet member in accordance with the present
`invention;
`
`FIG. 6 is a sectional view showing the structure of a liquid
`crystal display according to the prior art; and
`FIGS. 7 (a) and 7 (b) are plan views showing the
`distribution pattern of head particles on the diffusing layer of
`
`LGE_001103
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`5,706,134
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`3
`
`the light difl‘nsing sheet member in accordance with the
`present invention.
`
`DE'I‘AILED DESCRIPTION OF THE
`INVENTION
`
`Preferred embodiments of the present invention are be
`described in detail with reference to the figures of the
`accompanying drawings.
`In FIG. 1 (a), the reference numeral 1 denotes a light
`diffusing sheet member which essentially comprises a trans-
`parent base material sheet 2 and a light diffusing layer 3
`applied thereon.
`Preferable examples of the base material sheet 2 include
`a transpuent glass substrate and a synthetic resin film such
`as polyethylene terephthalate (PET). polycarbonate (PC) or
`a transparent acrylic resin having a thickness of about 20 to
`300 pm. There can be used any base material sheet which is
`transparent. does not inhibit light from passing and has
`elasticity, durability and the like. according to the use of the
`sheet
`
`The light diffusing layer 3 is formed by a synthetic resin
`5 (FIG. 1A) and the like as a base layer. There are mixed, in
`the synthetic resin 5 base layer. one or more kind(s) of bead
`particles 4 such as a urethane resin. a vinyl chloride resin. an
`acrylic resin or glass.
`In considaation of light diffusing eifects. the ratio of the
`beads particles 4 to the synthetic resin 5 is suitably 30 to
`90% by weight. If the ratio is smaller than 30% by weight.
`desirable light difinsing effects cannot be obtained. If the
`ratio is greater than 90% by weight. the adhesion of the bead
`particles 4 to the synthetic resin 5 is poor so that the beads
`particles 4 easily come off.
`In order to obtain good light diifusing effects, the size of
`the bead particles 4 is suitably about 1 to 50 um. In addition,
`it is preferred that two or more kinds of beads having
`different sizes are mixed. In consideration of working
`properties, strength and light difinsing effects, it is preferred
`that the synthetic resin 5 include an acrylic resin as a main
`agent having bead particles mixed therein, and a resin of a
`two-liquid hardening type using an isocyanate synthetic
`resin as a hardening agent and having a thickness of about
`15 to 20 pm (including no beads particles). However, there
`can be used other kinds of bead particles and synthetic resins
`by which desirable light diffusing effeas may be obtained
`The light diffusing layer 3 having beads particles may
`properly be applied on the top face of the base material sheet
`2 by a known blade roll coating method or the like.
`It is always required that particles 4a and particles 4b be
`mixed in the synthetic resin 5 so that light transmitted
`throng: the base material sheet 2 is uniformly diflused
`through the light diffusing layer 3. As shown in FIG. 1 (b),
`the particles 4a are completely buried in the synthetic resin
`5. and the particles 4b are partially buried in the synthetic
`resin 5 and at least partially project from the synthetic resin
`5. The ratio of particles to be mixed can suitably be changed
`according to the desired light diffusing ratio. The bead
`particles 4 may be distributed over the surface of the base
`material sheet 2 as shown in FIG. 7 (a), and may cover
`almost the entire surface of the base material sheet 2 as
`shown in FIG. 7 (b). In the latter case with greater density
`of the bead particles. light to be transmitted can be diffused
`more uniformly.
`As mentioned above and as shown in the drawings.
`relatively large size and small size beads are provided. The
`ratio of the number of small size beads to the large size beads
`is in the range from 1:99 to 99:1; preferably in the range
`
`4
`from 5:95 to 95:5. Some of the beads are totally embedded
`and others are partially embedded. The ratio of the number
`of totally embedded beads or particles to the partially
`embedded beads or particles is in the range from 1:99 to
`99:1; preferably in the range from 5:95 to 95:5.
`With the light diffusing sheet member having the above-
`mentioned structure, light A (FIG. 4 (a)) is transmitted from
`below the base material sheet 2 of the light diffusing sheet
`member 1, passes through the base material sheet 2. and into
`a layer having the particles 4a and 4b so as to be uniformly
`difl’used by the particles as shown in FIG. 4 (a) (see an arrow
`B). The particles 4a are completely buried in the synthetic
`resin 5 of the light diffusing layer 3 (see FIG. 1 (b)). The
`particles 4b are partially bmied in the synthetic resin 5 and
`at least partially project from the synthetic resin 5.
`With reference to FIG. 2 (a). the light diffusing sheet
`member of the second embodiment has the same structure as
`that of the first embodiment except that there is provided a
`metal deposition layer 6 which is formed by depositing a
`metal such as silver or aluminum on the bottom face of a
`base material sheet 2.
`
`Referring to the fight dilfnsing sheet member having the
`above—mentioned structure of the present invention (see
`FIG. 4 (b)). light C transmitted through the side of the base
`material sheet 2 of a light diffusing sheet member 1 is
`reflected by the metal deposition layer 6 formed on the
`bottom face of the base material sheet 2 and an interface
`between the base material sheet 2 and a light diffusing layer
`3 formed on the top face of the base material sheet 2. guided
`to the light difinsing layer 3 and then uniformly diffused in
`the same manner as in the first embodiment shown in FIG.
`4 (a).
`According to one manner of use. an adhesive layer 7 may
`be provided on the bottom face of the base material sheet 2
`as shown in FIG. 3 (a) and a printing portion 8 may be
`provided on the adhesive layer 7 as shown in FIG. 3 (b) so
`that patterns such as characters can be displayed. In addition,
`a release paper can be removably afixed to the adhesive
`layer 7 so as to attach the light difiusing sheet member 1 to
`an object. Those skilled in the art can easily understand the
`foregoing.
`Furthermore, a synthetic resin layer having bead particles
`such as silica or carbon mixed therein may be applied on
`cloth. nonwoven fabric. a compound base material sheet
`formed by aflixing a vinyl chloride resin sheet to cloth, or the
`like. In this case, there can be provided an excellent light
`diifusing sheet which can widely be used as an antireflection
`sheet.
`
`10
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`EXAMPLEI
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`5 Parts by weight of “PTC LN hardening agent"
`(manufactured by DAINICHI SEIKA KABUSHIKI
`KAISHA) as a hardening agent was mixed with 100 parts by
`weight of a coating main agent (“RUB coating agent"
`manufactured by DAINICI-II SEIKA KABUSHIKI
`KAISHA) containing acrylic beads (having a size of 5 to 40
`pm) as a resin of a two-liquid hardening type. The mixture
`thus prepared was applied at a thickness of 15 to 20 um
`(including no beads) on the top face of a polyethylene
`terephthalate (PET) sheet (“PET T-100” manufactured by
`DIAPHOYL KABUSHIKI KAISHA) as a base material
`having a thickness of 100 pm by a known blade roll coating
`method.
`The results of characteristic tests of a sheet member thus
`prepared are as follows:
`
`LGE_001104
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`LGE_001104
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`5
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`5,706,134
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`Optical characteristics:
`
`
`light transmittance
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`88.9%
`(by us K 7105 A method)
`34.99:.)
`(by us K 7105)
`10.7%
`(by JIS K 7105 A method)
`10“(£])
`(by us K 6911)
`Pencil hardne
`(not less than 41-I)
`(by us K 5400)
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`Hm
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`Surface reflectance:
`
`Surface electric resistance
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`Surface hardness
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`EXAMPLE 2
`
`5 Parts by weight of “PTC LN hardening agent”
`(manufactured by DAINICHI SEIKA KABUSHIKI
`KAISHA) as a hardening agent was mixed with 100 parts by
`weight of a coating main agent (“RUB coating agent”
`manufactured by DAINICHI SEIKA KABUSHIKI
`KAISHA) containing acrylic beads (having a size of 30 to 40
`pm) as a resin of a two-liquid hardening type. The mixture
`thus prepared was applied at a thickness of 15 to 20 um
`(including no beads) on the top face of a vinyl chloride sheet
`(“hard vinyl chloride sheet” manufactured by RIKEN
`VINYL KOGYO KABUSHEKI KAJSHA) as a base mate-
`rial having a thickness of 0.1 mm by a known blade roll
`coating method.
`The results of characteristic tests given to a sheet member
`thus prepared are as follows:
`Surface hardness:
`
`Pencil hardness (not less than 4 H) (by JIS K 5400)
`Taber's abrasion resistance test (not greater than 10‘3 g)
`(by ASTM D 1044)
`Adhesion:
`
`There was used a label having an adhesion of 1200 gf/25
`mm or more to a stainless plate.
`Alfixz
`
`40° C., 40 g/cm’ >04 hr.
`Evaluation:
`
`There was confirmed the presence of adhesion after
`release at an angle of 90°—no adhesion)
`Surface reflectance: not greater than 10% (by JIS K 7105 A
`method)
`According to the light diifusing sheet member having the
`above-mentioned structure of the present invention, a light
`diffusing layer is formed on the surface of a transparent base
`material sheet. The light difiusing layer is a transparent
`synthetic resin layer having transparent beads mixed therein.
`The beads have different sizes and include particles buried
`in the synthetic resin layer and particles which at least
`partially project from the synthetic resin layer:
`Thus, Light transmitted from below the base material
`sheet passes through the base material sheet and then
`through the light diffusing layer. Consequently, the light is
`uniformly difiused by the bead particles mixed in the light
`difiusing layer.
`Accordingly, if the light diffusing sheet member of the
`present invention is used as a diffusing plate provided on the
`back of a liquid crystal panel in a liquid crystal display, light
`transmitted from a light source can be diffused more uni-
`formly than in the prior art. Thus, there can be provided a
`light diffusing sheet member as a diifusing plate by which
`the luminance of a screen of a light diffusing plate liquid
`crystal display portion is suflicient and a user can view
`characters. graphics and the like displayed on the screen
`from different angles.
`
`20
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`25
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`35
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`55
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`60
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`LGE_001105
`
`In case a metal deposition layer is formed on the back of
`the base material sheet of the light diffusing sheet member
`according to the present invention, light transmitted through
`the side of the base material sheet is reflected by a metal
`deposition face and an interface between the base material
`sheet and the light diffusing layer and is guided to the light
`diffusing layer so as to be diffused uniformly.
`On the back of the liquid crystal panel in the liquid crystal
`display, the light diffusing sheet member can function as a
`reflecting plate, a guide plate and a diffusing plate according
`to the prior art.
`For example. in case the light diffusing sheet member of
`the present invention is placed on or afiixed to the front
`interior member of a car 20. in particular a top face 22 of a
`dash board 21 as shown in FIG. 5, light A transmitted
`through a front glass 24 is irregularly reflected.
`Consequently, the front interior member of the car 20, in
`particular the dash board, is mirrored in the front face of the
`front glass so that it is possible to prevent a driver's view
`from being interrupted.
`In order to prevent the light of lighting equipment from
`being reflected by the display portion of a transparent liquid
`crystal panel of a clock or a digital meter of a car, a screen
`of a word processor or a computer, and the like, so that the
`display portion or screen is hard to look at. the light diflusing
`sheet member of the present invention can be used on the
`surface of a member which should prevent light from being
`reflected, for example, can be allixed to the surfaces of
`members around a CRT (Cathode Ray Tube) of OA devices
`or the like. Thus, remarkable elfects can be obtained.
`Although the present invention has fully been described
`by way of example with refaence to the accompanying
`drawings, it is to be understood that various changes and
`modifications will be apparent to those skilled in the art.
`However, unless such changes and modifications depart
`from the scope of the invention, they should be construed as
`being included therein.
`What is claimed is:
`
`1. A light-diffusing sheet member comprising a transpar-
`ent base material sheet and a light-difiusing layer formed on
`the surface of said base material sheet and made of a
`transparent synthetic resin layer having transparent beads
`mixed therein;
`wherein said light-difiusing layer has beads of ditferent
`particle sizes, the ratio of said beads to said synthetic
`resin layer is 30 to 90% by weight, and said light-
`ditfusing layer has some of said beads buried therein
`and other of said beads projecting partially therefrom.
`2. A light-diifusing sheet member according to claim 1,
`wherein said beads comprise small beads and large beads in
`the quantity ratio of from 1:99 to 99:1.
`3. Alight-diffusing sheet member according to claims 1 or
`2, wherein said beads comprise the buried beads and the
`partially projected beads in the quantity ratio of from 1:99 to
`99:1.
`
`4. A light-diifusing sheet member comprising a base
`material sheet and a light-difiusing layer formed on the
`surface of said base material sheet and made of a synthetic
`resin layer having beads mixed therein;
`wherein said light-diffusing layer has beads of different
`particle sizes. and said light-diffusing layer has some of
`said beads buried therein and other of said beads
`projecting partially therefrom. said light-difiusing sheet
`member further comprising a metal deposition layer
`formed on the back of said base material sheet.
`
`*
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`*
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`III
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`3|!
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`*
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`LGE_001105
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`
`DATED
`
`INVENTORISI
`
`:
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`:
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`5,706,134
`
`January 6, 1998
`
`TERUAKI KONNO, ET AL.
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`On the title page, under
`
`[30] Foreign Application Priority Data,
`
`the data for the first application shou1d
`
`read Jun. 22, 1992 LIP} Japan .......... .. 4-042936 U
`
`I561 Referemes Cited:
`
`the eighth reference listed, should be corrected to
`
`read " 3,994,086 11/1976 Mizuochi
`
`-—.
`
`Signed and Sealed this
`
`Eighteenth Day of May, 1999
`
`Am-”5“'nK 0.[flC'€"
`
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`Q. 'l‘0Dl) l)lCKlNS()N
`
`LGE_001106
`
`LGE_001106