United States Patent [19]
`Funamoto et al.
`
`[54] SURFACE· TYPE ILLUMINATION DEVICE
`AND LIQUID CRYSTAL DISPLAY
`
`[75]
`
`Inventors: Tatsuaki Funamoto; Toru Yagasaki;
`Fumiaki Akahane, all of Suwa, Japan
`
`[73] Assignee: Seiko Epson Corporation, Tokyo,
`Japan
`
`[21] Appl. No.:
`
`204,374
`
`[22] PCT Filed:
`
`Jul. 13, 1993
`
`[86] PCTNo.:
`
`PCT/JP93/00965
`
`§ 371 Date: May 10, 1994
`
`§ 102(e) Date: May 10, 1994
`
`[87] PCT Pub. No.: W094/01795
`
`PCT Pub. Date: Jan. 20, 1994
`
`[30]
`
`Foreign Application Priority Data
`
`Jul. 13, 1992
`May 13, 1993
`
`[JP]
`[JP]
`
`Japan .................................... 4-184976
`Japan .................................... 5-111852
`
`Int. C1.6
`................................................... G02F 1/1335
`[51]
`[52] U.S. CI ..................................... 349/61; 349/5; 349/62
`[58] Field of Search .................................. 359/40, 42, 48,
`359/49, 50, 70; 362126, 31, 32, 330
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,729,067
`4,842,378
`4,974,122
`4,985,809
`5,057,974
`5,130,898
`5,134,549
`5,283,673
`5,363,294
`
`3/1988 Ohe ........................................... 362/26
`6/1989 Flasck et aI.
`.. ........................... 359/48
`11/1990 Shaw ......................................... 362/32
`1/1991 Matsui et aI .............................. 362/31
`10/1991 Milzobe .................................... 362126
`711992 Akahane ................................... 362/31
`7/1992 Yokoyama ................................ 362/31
`2/1994 Murase et aI ............................. 359/49
`11/1994 Yamamoto et aI ..................... 3621330
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`US005619351A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,619,351
`Apr. 8, 1997
`
`FOREIGN PATENT DOCUMENTS
`
`0317250
`0442529
`2632432
`54-40086
`166585
`62-102226
`63-45537
`63-124217
`1183626
`351476
`4102888
`8808149
`
`5/1989
`8/1991
`12/1989
`311979
`7/1986
`5/1987
`3/1988
`8/1988
`711989
`5/1991
`4/1992
`10/1988
`
`European Pat. Off ..
`European Pat. Off ..
`France.
`Japan .
`Japan .
`Japan .
`Japan .
`Japan .
`Japan .
`Japan .
`Japan .
`WIPO.
`
`OTHER PUBLICATIONS
`
`"Advancements in Backlighting Technologies for LCDs,"
`K. Hathaway, Spie Proceedings, High-Resolution Displays
`and Projection Systems, vol. 1664, Feb. 1992, pp. 108-116.
`Abstract for 62-102226 May 12, 1987, Japan.
`
`Primary Examiner-William L. Sikes
`Assistant Examiner-James A. Dudek
`Attorney, Agent, or Firm-Eric B. Janofsky
`
`[57]
`
`ABSTRACT
`
`A surface-type illumination device suitable for providing
`backlight in a liquid crystal display is disclosed. For
`example, an L-shaped fluorescent light can be used as an
`illuminant and mounted next to two edges of a substantially
`rectangular light guide plate. The comer of an edge portion
`between the two edges is removed. The fluorescent light, the
`length of whose illuminating portion is long, is positioned
`with an appropriate gap from the light guide plate allowing
`for illumination with high brightness and low power con(cid:173)
`sumption. Consequently, when the illumination device is
`used in a color liquid crystal display, appropriate backlight
`with high brightness can be obtained. Moreover, because the
`influence of the temperature from the illumination device is
`small, a stable color display can be achieved.
`
`18 Claims, 12 Drawing Sheets
`
`I
`
`"===1/=====1'1 25
`
`Sony Corp. Exhibit 1010
`
`SONY_000540
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 1 of 12
`
`5,619,351
`
`II
`
`---JI
`
`3
`FIG._1
`
`4
`
`36 10~
`
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`31
`
`SONY_000541
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 2 of 12
`
`5,619,351
`
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`SONY_000542
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 3 of 12
`
`5,619,351
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`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 4 of 12
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`5,619,351
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`
`SONY_000544
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 5 of 12
`
`5,619,351
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`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 6 of 12
`
`5,619,351
`
`21
`
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`SONY_000546
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 7 of 12
`
`5,619,351
`
`DOD·
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`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 8 of 12
`
`5,619,351
`
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`SONY_000548
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`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 9 of 12
`
`5,619,351
`
`I
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`SONY_000549
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 10 of 12
`
`5,619,351
`
`61
`
`41b
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`SONY_000550
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 11 of 12
`
`5,619,351
`
`SURFACE TEMPERATURE
`
`65
`
`35
`
`25 - - - - - - - - - - - - - - - - - - - - - -
`ROOM TEMPERATURE
`
`t
`
`POSITION DIRECTLY
`OVER THE
`LIGHT SOURCE
`
`FIG._18
`POSITION DIRECTLY J CENTRAL J
`
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`LIGHT SOURCE
`
`PORTION OF
`THE IMAGE
`
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`
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`
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`
`SURFACE TEMPERATURE
`
`~ -------------~--------
`ROOM TEMPERATURE
`
`END PORTION ~ CENTRALJ
`
`OF THE IMAGE
`
`PORTION OF
`THE IMAGE
`
`t
`
`POSITION DIRECTLY
`OVER THE LAMP
`LIGHT SOURCE
`
`SONY_000551
`
`

`
`u.s. Patent
`
`Apr. 8, 1997
`
`Sheet 12 of 12
`
`5,619,351
`
`82a
`
`82b
`
`91-1\
`
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`
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`
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`
`SONY_000552
`
`

`
`5,619,351
`
`1
`SURFACE-TYPE ILLUMINATION DEVICE
`AND LIQUID CRYSTAL DISPLAY
`
`FIELD OF THE INVENTION
`
`This invention relates in general to a thin, surface-type
`illumination device that can be used as a backlight for liquid
`crystal displays (LCD) and, in particular, to a suitable
`illumination device for use in a notebook computer display
`that provides high brightness with low power consumption 10
`as well as to a liquid crystal display that uses this illumi(cid:173)
`nation device.
`
`BACKGROUND OF THE INVENTION
`
`2
`such as microcomputers where thinness and small size are
`important.
`In accordance with the instant invention, a suitable illu(cid:173)
`mination device for color liquid crystal displays can be
`5 obtained that are small in size, lightweight, and have high
`and uniform brightness. Further, it is an object of the
`invention to provide a surface-type illumination device that
`can prevent heat generation and its resulting bad effects to
`the liquid crystal display panel.
`Another object of the invention is to provide a surface(cid:173)
`type illumination device that, without increasing the number
`of driver circuits for driving the fluorescent lights, displays
`a brightness higher than conventional illumination devices
`and restricts heat radiation.
`A further object of the invention is to generate a suitable
`diffusion pattern to realize a surface-type illumination
`device, this diffusion pattern being used in the illumination
`device.
`Still another object of the invention is to provide a stable
`liquid crystal display where the driver IC for driving the
`liquid crystal display panel is positioned so that it will not be
`affected by heat.
`
`Surface-type illumination devices with a cylindrical light 15
`source and a flat polarizer such as the devices described in
`Japanese Kokai No. 60-205576 and Japanese Kokai No.
`61-248079 are well-known. One such example is shown in
`FIG. 21. In the illumination device 90, cylindrical fluores(cid:173)
`cent light 92 is positioned on one side of the substantially 20
`rectangular and flat polarizer 91. The light introduced to
`polarizer 91 from fluorescent light 92 is reflected by the
`diffusion pattern printed on polarizer 91 and emitted from
`the surface of the polarizer at a fixed density of light.
`This type of surface illumination device, in recent years, 25
`has been used extensively as backlights for liquid crystal
`display panels. The use of liquid crystal display panels are
`increasing as displays in such things as laptop computers,
`televisions and cameras. The use of liquid crystal display
`panels for color displays is also increasing. As the size of 30
`personal computers and televisions become smaller, it is
`imperative that liquid crystal display panels become thinner
`and lighter.
`Accordingly, it is necessary that the surface-type illumi(cid:173)
`nation device used for liquid crystal display panels as a
`backlight, in correlation with the color displays, becomes
`thinner and lighter with less power consumption. Also, to
`allow for use in color displays, a sufficient brightness is
`necessary to clearly show the colors displayed in the liquid
`crystal. This requires the use of a high output fluorescent
`light in the illumination device. However, along with the
`light, heat is also radiated from the high-output fluorescent
`light. The effect of this heat, as shown in FIG. 22, is great.
`The temperature may rise 30°-40° C. above a normal
`temperature of 25° C. Consequently, when this type of
`illumination device is used as a backlight in an MIM active
`color display panel or in a STN passive color display panel,
`a special method to reduce the heat is necessary to control,
`to a certain extent, the color and brightness irregularities.
`In stead of using one high output fluorescent tube, it is
`also conceivable to increase the number of fluorescent tubes.
`In this way, it is possible to control to some extent the
`temperature increase due to the light source. However, as the
`number of fluorescent tubes is increased, many other prob(cid:173)
`lems appear. One of these problems is the variations in the
`illumination of the fluorescent tubes. Because the illumina(cid:173)
`tion intensity of florescent tubes varies according to each
`tube, it is necessary to adjust such things as the resistance
`within the fluorescent tube driver circuit to obtain a fixed
`illumination intensity. Consequently, in the case when sev(cid:173)
`eral fluorescent tubes are used in one illumination device,
`extra time is required during the manufacturing process to
`obtain a balanced and fixed illumination intensity.
`Another problem is the increased number of driver cir- 65
`cuits required to tum on the fluorescent tubes. The number
`of these driver circuits can not be easily increased in devices
`
`DISCLOSURE OF THE INVENTION
`
`35
`
`In accordance with the instant invention, by employing an
`illuminant longer than conventional illuminants, illumina(cid:173)
`tion with high illumination intensity is obtained without
`increasing the number of driver circuits for driving the
`illuminants and without concentrating the heat diffusion.
`Further, by bending the illuminant, light can be introduced
`along the polygon-shaped polarizer. Also, to maintain proper
`space between the polarizer and the illuminant and to
`increase the efficiency of the light introduced to the polar(cid:173)
`izer, a comer is removed from the edge of the polarizer. In
`other words, the surface-type illumination device of the
`instant invention comprises a polarizer which is polygon(cid:173)
`shaped and substantially transparent; a diffusion pattern
`40 arranged on one side of the polarizer, the diffusion pattern
`emitting substantially evenly from one side of the polarizer
`light that is introduced from the illuminant to the other side
`of the polarizer; and a cylindrically-shaped illuminant bent
`so that the illuminant faces at least two sides of the polarizer;
`45 wherein the edge sandwiched between the at least two sides
`is processed so that the comer does not protrude.
`Through using an illuminant bent along the polarizer, the
`length per cylindrically-shaped illuminant is long, and an
`illuminant with large illuminating area can be used. Conse-
`50 quently, the rise in temperature of the illuminant can be kept
`down and high brightness obtained. Furthermore, an
`increase in the number of driver circuits that drive the
`illuminant can be prevented. When bending an illuminant
`such as a fluorescent light to adjust for interference between
`the bent portion and the comer of the polarizer, the width or
`length of the entire illumination device becomes longer,
`preventing miniaturization. In the instant invention, by
`removing a comer of the polarizer, the distance between the
`polarizer and the illuminant can be kept within a fixed range
`60 for high incident efficiency, and thus, a highly efficient
`illumination device that is small in size can be realized.
`Further, by using a long illuminant as mentioned above,
`an improvement in conversion efficiency from power tp light
`is also attained. For example, in illuminants such as a
`fluorescent light, power to the illuminant is consumed by the
`cathode drop, which is due to the glow discharge, and
`consumed by positive column gradient voltage, which is due
`
`55
`
`SONY_000553
`
`

`
`5,619,351
`
`3
`to light emission. When a plurality of illuminants are used
`and the input voltage increased, the portion consumed by the
`cathode drop voltage significantly increases and an increase
`in the positive column gradient tendency for light emission
`is small. However, in the illumination device of the instant 5
`invention, which uses a long illuminant, power is efficiently
`converted into light as an increase in the positive column
`gradient voltage is smaller than the case when the number of
`illuminants is increased.
`The edge of the polarizer can be processed into many 10
`different shapes, for example, removing the comer in the
`shape of an isosceles triangle. In the case of the isosceles
`triangle, a high incident efficiency of light from the illumi(cid:173)
`nant to the polarizer can be maintained. It is desirable to
`make the length of one of the sides of the isosceles triangle
`to be removed in the approximate range of 0.6 times to 1.0 15
`times the smallest radius of curvature of the bent portion of
`the illuminant so as to realize a small-sized illumination
`device. Also, in order to prevent light incident from the edge,
`and to increase the uniformity of the light radiated from the
`polarizer, it is effective to include a shield at the edge portion 20
`to prevent introduction of light from the illuminant.
`Also, the comer of the edge may be removed in a
`diamond-shape. In order to make the incident efficiency high
`and keep the size of the device small, it is desirable to make
`the length of one of the sides of the comer removed in a
`diamond-shape within a range of 0.6 times to 1.0 times the
`smallest radius of curvature of the bent portion of the
`illuminant. Also, if all the comers are removed from the
`edges of the polarizer so that they do no protrude, the 30
`directionality of the polarizer disappears and the manufac(cid:173)
`turing process time required to position the polarizer
`becomes unnecessary.
`It is common to cover the illuminant with a reflector to
`increase the incident efficiency of the light from the illumi(cid:173)
`nant to the polarizer. When a bent illuminant such as the one
`described above is used, it is desirable for the reflector to be
`comprised of a straight first reflector and a second reflector
`positioned along two of the sides of the polarizer wherein at
`the edge, the first reflector is covered by the second reflector. 40
`It is also possible for the reflector to be comprised of a first
`reflector that covers the lower half portion of the illuminant
`on one side of the polarizer and a second reflector that covers
`the upper half of the illuminant from the other side of the
`polarizer.
`The diffusion pattern that diffuses light incident to the
`polarizer from the bent illuminant can be generated by the
`following method. In other words, to generate a diffusion
`pattern that evenly radiates, from the other side of the
`polarizer, light introduced from the illuminant to the polar- 50
`izer in an illumination device where a cylindrically-shaped
`illuminant is positioned near at least a first side and a second
`side of a substantially rectangular polarizer, the density
`distribution per unit area of the diffusion pattern can be
`found by: finding a predicted emitted light intensity distri(cid:173)
`bution for the y-direction along the first side based on the
`intensity of the light incident to the polarizer from the
`second side and the density distribution of a presupposed
`diffusion pattern; then finding a predicted emitted light
`intensity distribution for the x-direction along the second
`side based on the intensity of the light incident to the
`polarizer from the first side and the density distribution of
`the presupposed diffusion pattern; and then compensating
`the density distribution of the presupposed diffusion pattern
`so that the sum of the predicted emitted light intensity 65
`distribution for the x-direction and the predicted emitted
`light intensity distribution for the y-direction on arbitrary
`
`45
`
`4
`rectangular xy coordinates of the polarizer fit within a fixed
`range.
`When an edge reflector is installed at at least one of the
`two sides opposite the first side and the second side for
`reflecting the light from the inner part of said polarizer to
`said polarizer, it is good to compensate the density distri(cid:173)
`bution by computing the reflected light intensity incident
`from the edge reflector to the polarizer with a fixed attenu-
`ation factor; finding a predicted emitted light intensity
`distribution for at least one of the xy directions of the
`reflected light intensity; and adding this to the predicted
`emitted light intensity distribution found above.
`By printing the diffusion pattern described above on the
`polarizer or by putting on the polarizer a sheet with the
`pattern formed on it, light introduced from the bent illumi(cid:173)
`nant can be evenly radiated from the polarizer. Similarly,
`light can be evenly emitted by making the thickness of a
`polarizer with an even diffusion pattern inversely proportion
`to the compensated density distribution of the diffusion
`pattern.
`Effects of the heat from the illuminant can be minimized
`by using as a bent illuminant an L-shaped illuminant and by
`placing in a position opposite the illuminant a driver device
`25 such as a driver IC for driving the liquid crystal display.
`Consequently, as the threshold value of the driver does not
`become unstable due to the heat, a color display with stable
`contrast is obtained. Further, a high quality display with high
`brightness and a small illumination device is also obtained.
`Further, a stable, high quality display can be obtained that
`reduces heat using an even longer U-shaped illuminant. The
`brightness of the display is easy to adjust when illuminants
`such as L-shaped and U-shaped illuminants are used because
`nearly the same intensity of light is incident from the
`35 periphery of the polarizer. Of course, an O-shaped illumi(cid:173)
`nant can also be arranged around the periphery of a rectan(cid:173)
`gular polarizer as well as an illuminant bent to fit the shape
`of any other polygon.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a sketch of a liquid crystal display using the
`surface-type illumination device in accordance with the first
`embodiment of the invention.
`FIG. 2 is a cross-sectional view of FIG. 1 showing the
`structure of the liquid crystal display.
`FIG. 3 is a break-down view showing the structure of the
`liquid crystal display of FIG. 1.
`FIG. 4 is a break-down view showing the construction of
`the surface-type illumination device used in the liquid
`crystal display of FIG. 1.
`FIG. 5 is a top plan view illustrating the combination of
`the surface-type illumination device and the liquid crystal
`55 display panel shown in FIG. 4.
`FIG. 6 is an explanatory drawing showing the positioning
`of the polarizer and fluorescent light of the surface-type
`illumination device of FIG. 4.
`FIG. 7 is a cross-sectional view showing the relationship
`60 of the polarizer, fluorescent light, and reflector of the sur(cid:173)
`face-type illumination device of FIG. 4.
`FIG. 8 is an explanatory drawing showing the assembly of
`the reflector of FIG. 7.
`FIG. 9 is an enlarged view of the edge of the polarizer.
`FIG. 10 is an enlarged view showing several possible
`edge formations of the polarizer.
`
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`5,619,351
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`5
`FIG. 11 is an explanatory drawing showing the diffusion
`pattern formed on the diffusion sheet, this diffusion sheet
`being stuck to the polarizer.
`FIG. 12(a), which differs from FIG. 11, is a plan view
`showing a polarizer where the thickness has been changed.
`FIG. 12(b), which differs from FIG. 11, is a cross(cid:173)
`sectional view showing a polarizer where the thickness has
`been changed.
`FIG. 13 is a top plan view showing the combination of the 10
`liquid crystal display panel and illumination device in accor(cid:173)
`dance with the second embodiment of this invention.
`FIG. 14 is a cross-sectional view showing the relationship
`of the liquid crystal display panel, illumination device, and
`illuminant as shown in FIG. 13.
`FIG. 15 is a breakdown view of the structure of the
`surface-type illumination device shown in FIG. 14.
`FIG. 16 is an explanatory drawing showing the relation(cid:173)
`ship of the polarizer and the fluorescent light which is in the
`surface-type illumination device of FIG. 15.
`FIG. 17 is an explanatory drawing showing the diffusion
`pattern that is printed on the polarizer of FIG. 15.
`FIG. 18 is a graph showing the surface temperature of the
`liquid crystal display panel shown in FIG. 13.
`FIG. 19 is an explanatory drawing showing a relationship,
`different from above; of the_polarizer and the fluorescent
`light.
`FIG. 20 is an explanatory drawing showing a [still further
`different relationship] of the polarizer and the fluorescent 30
`light.
`FIG. 21 is an explanatory drawing showing a conven(cid:173)
`tional polarizer and fluorescent light.
`FIG. 22 is a graph showing the surface temperature of a
`liquid crystal display panel using a surface-type illumination 35
`device similar to the one shown in FIG. 21.
`
`20
`
`6
`formed by enclosing the liquid crystal, transparent elec(cid:173)
`trodes and such between two layers of transparent glass
`substrates 11 and 12. At side lOa of liquid crystal display
`panel 10, a plurality of driver ICs 13 are installed for
`latching pixel data for the rows and sending it to the liquid
`crystal display panel. Also, at side lOb, which is adjacent to
`side lOa, a plurality of driver ICs 14 are installed for latching
`pixel data for the columns and sending it to the liquid crystal
`display panel.
`Frames 30 and 31 are used to protect illumination device
`20 and to position it within the case. At the same time, it also
`fills the role of maintaining a fixed distance for gap 33
`between illumination device 20 and liquid crystal display
`panel 10, for example, 0.2-1 mm. For this reason, frames 30
`and 31 are prepared so that their lower halfs 34 and 35
`15 support illumination device 20 and their upper halfs 36 and
`37 act as spacers between illumination device 20 and liquid
`crystal display panel 10. In this example the frame is divided
`into two pieces, however, the number of pieces is not limited
`to two. For example, three pieces, four pieces, or even more
`is possible, and even just one piece is also conceivable.
`Furthermore, the frame need not cover the entire periphery
`of illumination device 20 or liquid crystal display panel 10.
`A plurality of pieces may be arranged in appropriate places.
`Illumination device 20 is a surface-type illumination
`25 device set up with a cylindrically-shaped fluorescent light 22
`at the edge of substantially rectangular polarizer 21. Fluo(cid:173)
`rescent light 22 is roughly L-shaped and is covered by
`reflectors 23a and 23b. Wires for supplying power to drive
`fluorescent light 22 extend from both ends of fluorescent
`light 22 and are connected to the driver circuit on the host
`side through connector 7 which is for turning on the light.
`FIG. 4 is a break-down view of illumination device 20 and
`will be used to explain the structure of this embodiment of
`the illumination device. lllumination device 20 is comprised
`of polarizer 21, which is substantially rectangular in shape
`and is missing the comer of edge 40, fluorescent light 22,
`which encompasses edge 40 in an L-shape, and reflectors
`23a and 23b, which cover fluorescent light 22 in the direc(cid:173)
`tion of polarizer 21 and efficiently reflect light from fluo-
`40 rescent light 22 to polarizer 21. On lower surface 21b of
`polarizer 21, the side opposite of the side where liquid
`crystal display panel 10 is arranged, pattern sheet 24, which
`is printed with diffusion pattern 50, and reflecting sheet 25
`are arranged in that order. On upper surface 21a of polarizer
`45 21, the side where liquid crystal display panel 10 is arranged,
`diffusion sheet 26 and prism sheet 27 are arranged. Edge
`reflective tape 28 is installed at edge 41a and 41b, oppOsite
`fluorescent light 22 of polarizer 21.
`Polarizer 21 is a transparent material whose index of
`refraction is greater than that of air. An index of refraction
`equal to or greater than 1.41 is desirable using such materials
`as acrylic resin, poly carbonate resin, amorphous polyole(cid:173)
`fine-type resin, and polystyrene resin. Use of these type of
`materials for polarizer 21 result in a critical angle of 45° or
`less. If upper surface 21a and lower surface 21b are smooth
`and mirror-like, the light incident from edges 41a, 41b, 4lc,
`and 41d, which are formed at right angles to surface 21a and
`21b, is completely reflected from surfaces 21a and 21b.
`Pattern sheet 24 is a transparent sheet with a fixed number
`60 of diffusion patterns 50 printed on it, the printed diffusion
`patterns being adhered to the lower surface 21b of polarizer
`21. Light incident from sides 41, to some extent, reach
`diffusion pattern 50 and, without being completely reflected
`will be diffused in the direction of upper surface 21a.
`65 Consequently, light incident from the fluorescent light by
`way of edges is emitted to the liquid crystal display panel 10
`from upper surface 21a.
`
`BEST MODE FOR IMPLEMENTATION OF THE
`INVENTION
`
`The embodiments of the instant invention are explained
`below using the above drawings as reference.
`
`EMBODIMENT 1
`
`FIG. 1 is a sketch ofliquid crystal display 1 in accordance
`with one embodiment of this invention. Liquid crystal
`display 1 is constructed with liquid crystal display panel 10
`and an illumination device to be described later sandwiched
`between upper case 2 and lower case 3. Upper case 2 and 50
`lower case 3 are fixed in place by tooth 4. The scanning data
`that comprises the image is supplied from the host side to
`each row or column through tape electrode 5 and tape
`electrode 6. This data is latched by a driver IC which will be
`described below, is synchronized, and is supplied to liquid 55
`crystal display panel 10 where the image is formed. Power
`is supplied from the driver circuit of the host side to the
`fluorescent light comprising the illumination device through
`connector 7, connector 7 extending past liquid crystal dis(cid:173)
`play 1 and used lighting.
`The basic structure of one embodiment of liquid crystal
`display 1 will be explained using the cross-sectional view of
`liquid crystal display 1 shown in FIG. 2 and the break-down
`view of liquid crystal display 1 shown in FIG. 3. In liquid
`crystal display 1, illumination device 20 is installed in lower
`case 3. Above that, liquid crystal display panel 10 is installed
`using frame 30 and 31. Liquid crystal display panel 10 is
`
`SONY_000555
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`5,619,351
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`Reflecting sheet 25 is a thin PET sheet with a thickness
`approximately 0.05-0.5 mm. Light coming from upper
`surface 21a from polarizer 21 through diffusion pattern 50
`travels through the diffusion sheet 26 or prism sheet 27,
`which are arranged on the upper portion of upper surface 5
`21a and light up liquid crystal display panel 10. However, a
`portion of the light is reflected through sheet 26 and 27 in the
`lower direction. The light reflected from the upper direction
`is returned to polarizer 21, among others, through reflecting
`sheet 25. Reflecting sheet 25 may also be aluminum or other 10
`non-PET material. Also, lower case 3 may be used in place
`of a reflecting sheet as a reflector. Further, the frame of a
`computer or such carrying the illumination device or liquid
`crystal display of the instant invention can also be used as a
`reflector in place of the reflecting sheet.
`Diffusion sheet 26 is an approximately 0.05-0.5 mm thin
`PET sheet or PC sheet. Diffusion sheet 26 diffuses the light
`that is reflected by diffusion pattern 50 and radiated from
`upper surface 21a. Diffusion pattern 50 is often formed in a
`narrow line configuration or net configuration. The light that 20
`is reflected by these types of patterns is diffused by diffusion
`sheet 26. The diffusion pattern carmot be recognized from
`the liquid crystal display panel 10. Diffusion sheet 26 is
`arranged with a very small layer of air between it and the
`upper surface 21a of polarizer 21. The angle mentioned 25
`above is maintained in regards to the angle of upper surface
`21a. Reflection sheet 26 is not limited to a PET sheet and
`such sheets as acrylic-type sheets, among others, may be
`used.
`Prism sheet 27, which is arranged on diffusion sheet 26, 30
`is made up of very small linear prisms lined in a cross(cid:173)
`sectional array. The angle of the light radiating from diffu(cid:173)
`sion sheet 26 is arranged to improve the illuminating inten(cid:173)
`sity of the liquid crystal display panel 10. Although the
`brightness can be improved through prism sheet 27, when 35
`sufficient brightness is achieved through diffusion sheet 26,
`prism sheet 27 can be omitted, thus reducing manufacturing
`cost.
`Fluorescent light 22, which is used as the light source of 40
`illumination device 20, is in an L-shape, and is positioned
`adjacent to edges 41c and 41d of polarizer 21. It is desirable,
`as will be explained later, to maintain a gap between edges
`4lc and 41d and fluorescent light 22 of around 0.8-1.5 mm.
`The comer of edge 40 of polarizer 21 is removed and the 45
`fluorescent light 22 is able to be positioned with the above
`noted gap. Also, through removing this comer, fluorescent
`light 22 and the comer of polarizer 21 are kept from
`touching and such things as damage to the fluorescent light
`can be prev