Patent
Right

Date
Case number

July 10, 20192019 (Ne) 10010

Court

Intellectual Property
High Court, First
Division- A case in which, with regard to presence or absence of infringement of the patentright related to the invention titled "lightguide plate and lightguide plate assembly",
the electronic book reader (defendant's product) sold by the appellee does not satisfy
the constituent feature that "diffraction grating provided on a rear surface of a plateshaped body" in the description in the scope of claims of the patent and a portion thatthe diffraction grating is provided on the rear surface of the plate-shaped body in theinvention is an essential part in the invention and does not satisfy the first requirementof the doctrine of equivalence.
Case type: Compensation for unjust enrichment
Result: Appeal dismissed
References: Article 70, paragraphs (1) and (2) of the Patent Act
Number of related rights, etc.: Patent No. 2865618
Summary of the Judgment
1

This case is a case in which, the appellant having the patent right related to theinvention titled "lightguide plate and lightguide assembly" alleged that the electronic
book reader (defendant's product) sold by the appellee is equivalent to the invention
according to the aforementioned patent right and belongs to the technical range
thereof, and the appellant suffered a loss corresponding to the profit by the sales
thereof and required compensation of 1.5 million yen and delay damages from theappellee on the basis of the compensation for unjust enrichment gained by the
infringer in Article 703 of the Civil Code and by clearly indicating that it is a part ofan amount corresponding to the royalty of the present patent right.
The court of prior instance judged that the aforementioned product sold by theappellee does not satisfy the requirements of the doctrine of equivalence anddismissed the appellant's request.

The appellant instituted this appeal and added theallegation of wording infringement.
2This judgment dismissed the appeal by finding as follows in brief:(1) Establishment of wording infringement
A. With regard to propriety of the appellant's new allegation of the wording
infringement in addition to the allegation of infringement under the doctrine ofequivalence in the court of second instance, the allegation on details of the technicalmatters related to the technical range of the patent invention and approval ordisapproval thereof do not constitute admission of major facts and do not bind theⅰcourt or the parties concerned and thus, they are not approved due to confliction withthe established admission, and even if the wording infringement is examined in theappeal court for this case, it is not found that completion of the lawsuit would bedelayed and thus, dismissal under Article 157, paragraph (1) of the Code of Civil
Procedure is not rendered.
B. The constituent feature A is understood to describe the contents of theinvention by defining one of the both surfaces of the transparent plate -shaped body as
the "rear surface" and the other as the "front surface" from the context of the portion
that "diffracted to the front surface side of the plate shaped body by the diffraction
grating provided on the rear surface of the plate-shaped body".
Which side of the surface of the transparent plate-shaped body that the constituent
feature defines as the "rear surface" or the "front surface" should be interpreted byconsidering the problem, the solution thereof, and the effect of the present inventionin addition to that the constituent feature B describes that "at least one of a sectional
shape of the diffraction grating or a ratio of grating part width/non-grating part width
in a unit width is characterized to be changed so that brightness on the surface of thelightguide plate increases and is uniformized".
It is found that the present invention is characterized in that, in order to solv e theproblem of illuminating a liquid crystal display panel or the like uniformly and withhigh brightness, a diffraction grating is provided on a surface on a side opposite to an
illuminated surface in both surfaces of the plate-shaped body which is a lightguideplate so that the light incident to the plate-shaped body which is the lightguide plate
exerts uniform and high brightness on the side of the illuminated surface by adiffracting function of this diffraction grating.
From a viewpoint of the role played by the light emitted from the light source inthe aforementioned mechanism, the side where the effect of the uniform and highbrightness is exerted by advancing of the light emitted from the light source isunderstood to be the "front surface" side.
Then, it is reasonable to interpret that the "rear surface" referred to in the"diffraction grating provided on the rear surface of the plate-shaped body" of theconstituent feature A is the surface located opposite to the illuminated surface which
is a surface on which the light emitted from the light source advances and the effect of
the uniform and high brightness is exerted occurs.

The aforementioned

interpretation also follows the description in the embodiment of the present
Description.
C. In the defendant's product, the light emitted from the light source is expected toⅱexert the uniform and high brightness on the display side; that is, on the lower side ofthe lightguide.

Moreover, the light transmitted through a micro-structural bodyprovided on the lightguide is used for illuminating the display.

Since the side where

this light advances, and where the effect of exerting the uniform and high brightness
is generated, is the front surface, the micro-structural body of the defendant's productis assumed to be provided on the "front surface" of the light guide and is not provided
on the "rear surface".
The defendant's product does not satisfy the "diffraction grating provided on therear surface of the plate-shaped body" of the constituent feature A.
(2) Establishment of infringement under the doctrine of equivalence
In the present invention, the diffraction grating (marked line groove) is worked on
the surface (rear surface) opposite to the side where the effect of illumination i s
generated in the both surfaces of the lightguide plate made of a transparent plate shaped body at an interval determined appropriately on the basis of an incident angle
and a critical angle of the light, whereby the light incident from one end surface of thelight guide plate toward the rear surface is diffracted by the diffraction grating toward
the surface (the surface where the effect of illumination is generated) of the lightguideplate, and the front surface of the lightguide plate is illuminated extremely brightly by
the outgoing light with high intensity orthogonal to that and the total reflection light
led into the lightguide plate.

(omitted)

In view that such mechanism constitutes thetechnical idea of the present invention, the portion where the diffraction grating isprovided on the rear surface of the plate-shaped body in the present invention is theessential part of the present invention.
Since the defendant's product does not include the portion that the diffraction
grating is provided on the rear surface of the plate-shaped body as having been
already examined in the relationship with the wording infringement, the different
point between the present invention and the defendant's product is the essential part in
the end and does not satisfy the first requirement of the doctrine of equivalence.

ⅲ

Judgment rendered on July 10, 20192019 (Ne) 10010, Appeal case of seeking compensation for unjust enrichment (Courtof prior instance: Osaka District Court 2016 (Wa) 4759)
Date of conclusion of oral argument: May 29, 2019
Judgment
Appellant: Shimada Precision, Co., Ltd.
Appellee: Amazon.com Int'l Sales, Inc.

Main text
1. The appeal shall be dismissed.
2. The appellant shall bear the cost of the appeal.
Facts and reasonsNo. 1 Gist of the appeal
1. The judgment in prior instance shall be reversed.
2. The appellee shall pay to the appellant 1.5 million yen and 5% interest per
annum from June 11, 2016 to completion of the payment.
No. 2 Outline of the case (Abbreviations follow those in the judgment in priorinstance unless otherwise specified)
1. This case is a case in which the appellant having the present patent right related
to the invention titled "lightguide plate and lightguide plate assembly" (Patent No.
2865618) alleged that the electronic book reader sold by the appellee has aconfiguration equivalent to that described in the scope of claims according to theaforementioned patent right and belongs to the technical range of the patent inventi on,
and the appellant suffered from a loss corresponding to the profit by the sales thereof,
and required compensation of 1.5 million yen from the appellee on the basis of theright to claim compensation for unjust enrichment in Article 703 of the Civil Codeand by clearly indicating that it is a part of an amount corresponding to the royalty ofthe present patent right, and also claimed payment of delay damages at the rate of 5%
per annum prescribed under the Civil Code from June 11, 2016, the day following thedate of service of the complaint, to completion of the payment.
1Since the court of prior instance judged that the aforementioned product sold by
the appellee did not satisfy the requirements of the doctrine of the equivalent anddismissed the appellant's claim, the appellant instituted the present appeal.
2. Since the basic facts are as described in No. 2, 2 in the "Facts and reasons" inthe judgment in prior instance, they are cited herein.
3. Issues(1) Whether the defendant's product belongs to the technical range of the present
invention (issue 1)
A. Whether the wording thereof belongs to the technical range of the present
invention (issue 1-1. Added in this court)
B. Whether the defendant's product is equivalent to the present invention andbelongs to the technical range thereof (issue 1-2)
(2) Whether the present patent should be invalidated in the patent invalidation trial(issue 2).
A. Violation of Article 29-2 of the Patent Act by Exhibit Otsu 7 (issue 2-1)
B. Violation of Article 29-2 of the Patent Act by Exhibit Otsu 8 (issue 2-2)
C. Lack of novelty by Exhibit Otsu 9 (issue 2-3)
D. Lack of inventive step with Exhibit Otsu 9 as the primary cited reference (issue
2-4)
E. Violation of support requirements (issue 2-5)
(3) Amounts of appellant's loss and appellee's profits (issue 3)(omitted)
No. 4 Judgment of this court
1. Establishment of wording infringement (issue 1-1)
(1) Propriety of new allegation of wording infringement in this court
A. The appellant exclusively alleged the infringement under the doctrine ofequivalent in the court of prior instance and since it was decided that the firstrequirement (non-essential part) of the doctrine of equivalent was not fulfilled, theappellant added the allegation of wording infringement in this court that thedefendant's product belongs to the technical range of the present invention also in thewording.
B. In this regard, although the appellant stated in the court of prior instance that"the fact that the diffraction grating of the defendant's product is provided on theguideline surface", the appellee alleges that the allegation of the fact that the2diffraction grating of the defendant's product is provided on a rear surface of theguideline in this court conflicts with the established admission and is not allowed.
However, the allegation on details of the technical matters related to the technicalrange of the patent invention and approval or disapproval thereof do not constituteadmission of major facts and thus, do not bind the court or parties concerned.
Thus, it is not said that the aforementioned allegation by the appellant is not
approved due to confliction with the established admission.
C. The appellee alleges that the appellant's aforementioned allegation mentioning
establishment of the wording infringement falls under a belated attack method andshould be dismissed under Article 157, paragraph (1) of the Code of Civil Procedure,
but since it is not found that completion of the lawsuit is delayed by examination ofwording infringement in this court, the appellant's aforementioned allegation shall not
be dismissed under Article 157, paragraph (1) of the Code of Civil Procedure even on
the ground of the examination history of the court of prior instance.
(2) Establishment of wording infringement
A. Description of scope of claims
The constituent features of the description of the scope of claims in this case are
separately described as follows:
C. A lightguide plate
A. which is a lightguide plate for diffracting light from a light source incident atleast within a range from one end surface of a transparent plate-shaped body to a front
surface side of the plate-shaped body by a diffraction grating provided on a rearsurface of the plate-shaped body,
B. characterized in that at least one of a sectional shape of the diffraction grating
and a ratio of a grating portion width/non-grating portion width in a unit width iscaused to be changed so that brightness on the front surface of the lightguide plateincreases and is uniformized.
B. Description in Description of this case
The "Detailed Description of the Invention" in Description of this case has thefollowing description (Exhibit Ko 6).

(For the drawings, see the attached list of

drawings.)(A) Technical field of the invention
The present invention relates to a lightguide plate used for a backlight of a liquid
crystal display device and the like or a light emission inductive plate ([0001]).
(B) Prior Art
In conventionally known planar illuminating devices used for a backlight of a3liquid crystal display device, a lightguide plate made of a transparent acrylic resin
having a large number of multi-surface prisms on a lower surface is provided ([0002]),
and when the light source of the liquid crystal display device is turned on in a darkplace, light incident toward the lower surface of the lightguide plate from the lightsource is led to a far place by reflection on the multi-surface prism while most of it istotally reflected in the lightguide plate and thus, the liquid crystal display panel can beilluminated brightly from below with less uneven brightness ([0003]).
(C) Problem to be Solved by the Invention
However, in the aforementioned planar illuminating device, the multi-surface
prisms provided in a large number on the lower surface of the lightguide plate have
one side of approximately 0.16 mm, for example, which is considerably larger than awavelength of the light, and since each prism individually and totally reflects the lightwithout collaboration, if the brightness of the lightguide plate is to be improved as awhole, there have been problems that irregular reflection occurs at a spotcorresponding to a valley between each of the prisms, a light amount toward an uppersurface decreases, and extreme light/dark contrast occurs on the upper surface which
is an illuminated surface.

Moreover, when this planar illuminating device is used forthe liquid crystal display device driven by a battery cell, the light source needs to beilluminated with a large electric current in order to compensate for the decrease in thelight amount toward the illuminated surface and to obtain high brightness and thus, alife of the battery cell becomes short and long-time use cannot be obtained, which isalso a problem ([0004]).
An object of the present invention is to provide a lightguide plate which canobtain brightness which is considerably higher and more uniform than that of theconventional planar illuminating device across the entire illuminated surface by using
a diffraction phenomenon based on the property of light wave and not the totalreflection by the prism using geometrical optics of the light and thus, lon ger life of
the battery can be realized by reduction in power consumption of the light source([0005]).
(D) Means for Solving the Problem
The present invention is a lightguide plate for diffracting light from a light source
incident within a range from at least one end surface of a transparent plate-shaped
body to a front surface side of the plate-shaped body by a diffraction grating provided
on a rear surface of the plate-shaped body, characterized in that at least one of thesectional shape of the diffraction grating and a ratio of a grating portion width/nongrating portion width in a unit width is caused to be changed so that brightness on the4front surface of the lightguide plate increases and is uniformized ([0006]).
Figure 1 shows an embodiment of the present invention, in which diffraction
gratings (marked line grooves) are worked at an interval d on the rear surface of thelightguide plate made of a transparent plate-shaped body.
The light incident toward the rear surface from the one end surface of thelightguide plate is diffracted by the diffraction grating toward the front surface of thelightguide plate, and the light with an incident angle larger than a critical angle φ istotally reflected by the front surface and led to a far place through the lightguide plate,while the light with the incident angle smaller than the critical angle φ exits outward
from the front surface.

Therefore, by adjusting the incident angle of the light to therear surface and by appropriately determining the interval d of the grating in a
relationship with the wavelength of the light source, the front surface of the lightguideplate is illuminated extremely brightly by outgoing light with high intensity
orthogonal thereto and the totally reflected light is led into the lightguide plate (see[0007], Figure 1 in the attached list of drawings).
(E) Embodiment of the Invention
Figure 2 in the attached list of drawings illustrates an embodiment of thelightguide plate used for the backlight of the liquid crystal display device in a working
example of the present invention.
The aforementioned liquid crystal display device is made of a liquid crystal
display panel 10 and a planar illuminating device 1 provided on a lower part thereof.
The planar illuminating device 1 is constituted by a lightguide plate 2 made of atransparent plastic resin on which a diffraction grating 3 is provided on a rear surface
2b, a fluorescent tube 4 having a cold cathode or a semi-hot electrode as a light source
arranged along a thick-side end side 2c of this lightguide plate 2, a reflector 5 which
covers a surface other than a front surface 2a of the lightguide plate 2 and thefluorescent tube 4 so as to surround them and reflects the light, a diffusion plate 6
arranged in parallel on the front surface 2a side of the lightguide plate 2, and a prism
sheet 7 for collecting light and arranged in parallel on the front surface side of this
diffusion plate 6 ([0013]).
The rear surface 2b of the lightguide plate 2 is inclined at an angle of 0.5° to 5°
with respect to the front surface 2a so that the light incident substantially in parallelfrom the fluorescent tube 4 can be received on the whole surface and has thediffraction grating 3 molded/worked as a fine marked line groove.

The gratinginterval d of the diffraction grating 3 is set so that lower-order diffraction light isemitted substantially perpendicularly from the front surface 2a and matched with a5direction of total reflection.

Moreover, the ratio of grating portion width/non-grating

portion width in a unit width of the diffraction grating 3 is set so as to gradually
become larger with increasing distance from the end side 2c so that a diffraction lightamount increases in accordance with a decrease in an amount of light reaching thegrating from the fluorescent tube 4.

The unit width here refers to the sum of one

grating portion width and one non-grating portion width and is a width of a unit
section.

On the rear surface 2b of the lightguide plate 2 in Figure 2, 11 sections eachhaving a unit width illustrated schematically are provided and are indicated by a boldline portion for each section of the grating portion width and a thin line portion foreach section of the non-grating portion width, and it can be understood that thediffraction light amount increases since a rate of the bold line portion in each section ;that is, the grating portion width, increases with increasing distance from the end side
2c ([0014]).
The planar illuminating device 1 having the lightguide plate 2 with theaforementioned configuration illuminates the liquid crystal display panel 10 asfollows.

White light emitted from the fluorescent tube 4 enters the lightguide plate 2

substantially horizontally from the end side 2c, hits the entire surface of the rearsurface 2b inclined at an angle of 0.5° to 5°, and is diffracted by collaboration withadjacent smooth surfaces between the large number of marked line grooves of thediffraction grating 3 provided on this entire surface, and the lower-order (1 to 3 order,
for example) diffraction light with high intensity is emitted substantiallyperpendicularly from the front surface 2a of the lightguide plate 2 as an arrow in the
figure.

In the diffraction grating 3, since the fine and large number of marked line

grooves collaborate and synergistically act on the order of 1/100, emission light withintensity extremely higher than a conventional triangular-pyramid prism can beobtained.

The grating portion width/non-grating portion width in a unit width of thediffraction grating 3; that is, diffraction efficiency of the grating (a ratio of thediffraction light intensity to incident light intensity) becomes larger with increasing
distance from the end side 2c on the fluorescent tube 4 side and thus, the diffraction
light amount increases in accordance with a light amount decrease with increasing
distance from the light source, and the front surface 2a of the lightguide plate 2 whichis the illuminated surface is illuminated with high brightness and extremely uniformly([0016]).
(F) Advantageous Effect of the Invention
Since, in the lightguide plate of the present invention, at least one of the sectional
shape and a ratio of the grating portion width/non-grating portion width in a unit
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width of the diffraction grating provided on the rear surface of the transparent plate shaped body to which the light from the light source is incident within a range at leastfrom the one end surface is caused to be changed so that the brightness on the front
surface of the lightguide plate increases and is uniformized, unlike the prism on theconventional lightguide plate rear surface in which a dimension is larger than the
wavelength of the light and the light is geometrically-optically and totally reflectedindividually without mutual collaboration, the fine gratings adjacent to each other by
the unit of micron collaborate and are synergized, and the light as wave can bediffracted extremely strongly and moreover, the sectional shape or the ratio of thegrating portion width/non-grating portion width in a unit width is adjusted so that thegreater the decrease in the light amount reaching from the light source with increasing
distance from the one end surface, the stronger the diffraction of the light and thus,
the front surface of the lightguide plate is illuminated with high brightness andextremely uniformly.

By applying this lightguide plate to the liquid crystal display

device driven by a battery cell, a liquid crystal television, a light emission inductive
plate displaying an emergency exit, or the like, bright and uniform illumination can beobtained with power consumption extremely lower than before ([0023]).
C. Interpretation of "diffraction grating provided on a rear surface of the plateshaped body"
The constituent feature A is understood to describe the contents of the invention
by defining one of the both surfaces of the transparent plate-shaped body as the "rearsurface" and the other as the "front surface" from the context of the portion that"diffracted to the front surface side of the plate-shaped body by the diffraction grating
provided on the rear surface of the plate-shaped body".
Which side of the surface of the transparent plate-shaped body that the constituent
feature defines as the "rear surface" or the "front surface" should be interpreted byconsidering the problem, the solution thereof, and the effect of the present inventionin addition to that the constituent feature B describes that "at least one of the sectional
shape of the diffraction grating or a ratio of the grating part width/non-grating part
width in a unit width is characterized to be changed so that brightness on the surfaceof the lightguide plate increases and is uniformized".
The problem and the solution thereof of the present invention, and its
advantageous effect are as described in the aforementioned B, and in short, it is foundthat the present invention is characterized in that, in order to solve the problem ofilluminating a liquid crystal display panel or the like uniformly and with highbrightness, a diffraction grating is provided on a surface on a side opposite to an
7

illuminated surface in the both surfaces of the plate-shaped body which is a lightguideplate so that the light incident to the plate-shaped body which is the lightguide plate
exerts uniform and high brightness on the side of the illuminated surface by adiffraction function of this diffraction grating.
From a viewpoint of the role played by the light emitted from the light source inthe aforementioned mechanism, the side where the effect of the aforementioned
uniform and high brightness is exerted by advancing of the light emitted from thelight source is understood to be the "front surface" side.
Then, it is reasonable to interpret that the "rear surface" referred to in the"diffraction grating provided on the rear surface of the plate-shaped body" of theconstituent feature A is the surface located opposite to the illuminated surface which
is a surface on which the light emitted from the light source advances and the effect ofexerting the uniform and high brightness occurs.
The aforementioned interpretation also follows the description in the embodimentof the present Description (aforementioned B (D) and (E)).
D. Configuration of defendant's productAll the defendant's products have a structure made of three layers; that is, [i]lightguide, [ii] touch screen, and [iii] display from above between upper and lower
frame bodies, and the structures and features of the lightguides do not have particulardifference among the first to third generation products (the product of the third
generation is as illustrated in the attached Figure 1 in the judgment in prior instance;
there is no dispute).
In the lightguide, a large number of fine structural bodies configured irregularly
by nano-imprinting in a unit pixel of 200 μm x 200 μm are provided diagonally with awidth XXXX of a projecting part and a width YYYY of a recess part.

They areprovided so that the length and/or the number of fine structural bodies in the unit
pixel increase with increasing distance from the light source, and an area of the finestructural body portion increases (the outline thereof is as in the attached Fig ure 2 in
the judgment in prior instance; there is no dispute).
In the defendant's product, the light emitted from the light source is expected toexert uniform and high brightness on the display side; that is, on a lower side of thelightguide.

Moreover, the light transmitted through a micro-structural body provided

on the lightguide is used for illuminating the display.

Since the side where this lightadvances, and where the effect of exerting the uniform and high brightness isgenerated, is the front surface, the micro-structural body of the defendant's product isassumed to be provided on the "front surface" of the lightguide, and is not provided
8

on the "rear surface".
E. Fulfillment of constituent feature(A) As described above, the defendant's product is considered not to satisfy the"diffraction grating provided on the rear surface of the plate-shaped body" of theconstituent feature A.
(B) Appellant's allegation
The appellant pointed out that the light diffracted to the front surface side of theplate-shaped body by the fine structural body of the defendant's product includes
transmitted diffraction light and reflected diffraction light and tried to makeinterpretation on front/rear on the basis of the reflected diffraction light, but since thedisplay of the defendant's product is illuminated only by the transmitted light, theappellant's allegation is not grounded.
(3) Summary
Therefore, it should be considered even with the new allegation by the appellant
that the defendant's product cannot be found to belong to the technical range of thepresent invention in view of the wording thereof.
2. Establishment of infringement under the doctrine of equivalent (issue 1-2)
(1) As described above, in the defendant's product, since the fine structural body isprovided on the "front surface" of the lightguide, it has a portion different from thepresent invention.
The technical range of the patent invention is established by wording
interpretation of the configuration described in the scope of claims in principle, buteven if there is a portion different from the product manufactured or the like by thecounterpart in the configuration described in the scope of claims, when [i] the portion
is not an essential part of the patent invention (first requirement); [ii] the object of thepatent invention can be achieved and the same working effects are exerted even if the
portion is replaced with the target product or the like (second requirement); [iii] bymeans of the replacement as above, a person having ordinary knowledge in thetechnical field to which the invention belongs (a person ordinarily skilled in the art)
could have easily conceived of the patent invention at the time of manufacture or the
like of the target product or the like (third requirement); [iv] the target product or the
like is not identical to a well-known art at the time of filing of the patent invention orit could not have been easily conceived of by the person ordinarily skilled in the art
from this at the filing (fourth requirement); and [v] there are no special circumstancessuch that the target product or the like is intentionally excluded from the scope ofclaims in the filing procedure of the patent invention (fifth requirement), it is9reasonable to consider that the target product or the like is equivalent to theconfiguration described in the scope of claims and belongs to the technical range ofthe patent invention (Supreme Court 1994 (O) 1083, the same on February 24, 1998,
Third Petty Bench Judgment/Collection of Court Precedents of Civil Cases ,Vol 52,
No. 1, page 113).
(2) First requirement of the doctrine of equivalent (non-essential part)A. Finding of essential part in the patent invention
An essential value of the invention to be protected by the Patent Act is a point thata solution based on a unique technical idea not found in the prior art for realizing
solution of the technical problem which could not be achieved by the prior art wasdisclosed with specific configuration to society and thus, the essential part in thepatent invention is interpreted to be a feature part constituting the unique technicalidea not found in the prior art in the description of the scope of claims of the patentinvention.
Moreover, it is reasonable to approve the essential part by finalizing the feature
portion constituting the unique technical idea not found in the prior art in thedescription of the scope of claims of the patent invention by grasping the problem andthe solution of the patent invention and the effect thereof on the basis of thedescription in the scope of claims and Description.
In finding of the above, since the essential value of the patent invention isdetermined in accordance with a degree of contribution in comparison with the prior
art in the technical field, it is reasonable to find the same from comparison in thedescription of the scope of claims and Description and particularly with the prior art
described in the Description.
In determination on the first requirement; that is, in determination on whether or
not the different part from the target product or the like is a non-essential part, it isreasonable to determine whether the target product or the like includes in common theessential part of the patent invention finalized as above, and if it is found to be
included, to determine that the different part is not the essential part.
B. Establishment of first requirement in this case
The description of the scope of claims and Description according to the present
invention is as above (1(2), A and B) and in summary, the present invention relates tothe planar illuminating device used for the liquid crystal display device, and with theprior art in which a large number of multi-surface prisms are provided on the lower
surface of the lightguide plate, there have been problems that irregular reflection
occurs and the light amount toward the upper surface decreases, and extreme
10dark/bright contrast is generated on the upper surface which is the illuminated surface
and the like, and in order to solve the problem of illuminating the liquid crystal
display device with uniform and high brightness, a diffraction grating is provided on asurface on the side opposite to the illuminated surface in the both surfaces of theplate-shaped body which is the lightguide plate, and the light incident to the plateshaped body which is the lightguide plate is allowed to exert uniform and highbrightness on the side of the illuminated surface by the diffraction function of thisdiffraction grating.
The diffraction grating is provided on the surface on the side opposite to theilluminated surface because, according to the description in Description of thiscase(1(2)B (D), (E), and (F)), in the present invention, the diffraction grating (marked
line grooves) is worked on the surface (rear surface) opposite to the side where theeffect of illumination is generated in the both surfaces of the lightguide plate made ofa transparent plate-shaped body at an interval determined appropriately on the basis of
an incident angle and a critical angle of the light, whereby the light incident from theone end surface of the lightguide plate toward the rear surface is diffracted by thediffraction grating toward the surface (the surface where the effect of illumination is
generated) of the lightguide plate so that the front surface of the lightguide plate is
illuminated extremely brightly by the outgoing light with high intensity orthogonal tothat and the total reflection light led into the lightguide plate, and it is found that theabove is the mechanism of the diffraction function in the present invention.
In view that such mechanism constitutes the technical idea of the present
invention, provision of the diffraction grating on the surface on the side opposite to
the illuminated surface; that is, the portion where the diffraction grating is provided
on the rear surface of the plate-shaped body in the present invention should beconsidered to be an essential part in the present invention.
Since the defendant's product does not include the portion that the diffraction
grating is provided on the rear surface of the plate-shaped body as having been
already examined in the relationship with the wording infringement, the different
point between the present invention and the defendant's product is the essential part in
the end and thus, it should be considered that the first requirement of the doctrine ofequivalent is not satisfied.
(3) Summary
As described above, it cannot be considered that the defendant's product isequivalent to the present invention and belongs to the technical range thereof, andinfringement under doctrine of equivalent of the present patent right cannot be11approved, either.
3. Conclusion
As described above, neither the wording infringement nor the infringement under
doctrine of equivalent is established in this case.

Then, the claim for compensationof unjust enrichment in this case is not grounded, without even determining on
propriety of defense of patent invalidation, since the cause of claim is not approved.
Thus, the judgment in prior instance which dismissed the appellant 's claim isreasonable and the appeal shall be dismissed since the appeal is not grounded, and thejudgment shall be rendered as in the main text.
Intellectual Property High Court, First Division
Presiding Judge: TAKABE Makiko
Judge: KOBAYASHI YasuhikoJudge: SEKINE Sumiko

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Attachment
List of drawings

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