JP2003322840A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin and lightweight liquid crystal display with excellent display quality. <P>SOLUTION: The liquid crystal display has a cut part for arranging a point light source at one or two or more corner parts (α) in rectangular transparent cell substrates (10, 20) forming a liquid crystal cell. The cell substrates has a transparent layer which has a refractivity lower than the substrates and which is provided on the liquid crystal side. Further, on the outside, an optical path control layer (40) is provided and which has an optical path conversion slant surface (Z) that reflects light made incident from the cut part into the cell substrate in the substrate direction. Consequently, liquid crystal displays of transmitting, reflective and semi-transmitting types and a dual purpose type for external light/illumination all with excellent display quality can be constructed which compactly store the point light source, have a small-size and thin structure illumination mechanism that efficiently transmits the incident light from the point light source over the entire substrate and evenly illuminates the liquid crystal by efficiently performing optical path conversion of the transmitted light via the optical path control layer and which have excellent thinness, small weight, brightness and brightness uniformity. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transmissive type, a reflective type, a semi-transmissive type, and an external light / illumination dual type, which has a uniform surface emission even for a point light source such as a light emitting diode, is thin and lightweight and has excellent display quality. Liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, there has been known a transmissive or reflective liquid crystal display device in which a substrate on the viewing side or the back side of a liquid crystal cell is provided with prismatic irregularities for reflecting incident light to the liquid crystal side ( JP 2001-318379, JP 2001
-356327). These are a thin liquid crystal cell in which the side-light type light guide plate for forming a backlight or a front light is omitted by forming an illumination mechanism with the prismatic irregularities, the cell substrate and a linear light source arranged on the side surface thereof. It is possible to reduce the weight. However, there is a problem that it is difficult to meet further demands for size reduction and weight reduction in the field of liquid crystal panels such as mobile phones by using a linear light source.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to develop a liquid crystal display device which is thin and lightweight and has excellent display quality.

[0004]

According to the present invention, a rectangular transparent cell substrate forming a liquid crystal cell has a missing portion for arranging a point light source at one or more corners, and the cell substrate has a liquid crystal side. In addition to having a transparent layer having a refractive index lower than that of the substrate, and having an optical path control layer on the outside, the optical path control layer causes light in the direction of the substrate that has entered the cell substrate from the missing portion to the liquid crystal in the liquid crystal cell. The present invention provides a liquid crystal display device having an optical-path changing slope that reflects in a direction.

[0005]

According to the present invention, the point light source can be arranged in the missing portion of the corner of the cell substrate and can be accommodated compactly, and the incident light from the point light source can be efficiently transmitted throughout the substrate. , It is possible to form a small and thin illumination mechanism that efficiently changes the optical path of the transmitted light through the optical path control layer to illuminate the liquid crystal with good uniformity, and has a good display quality with excellent thinness and lightness, brightness and uniformity. It is possible to form a transmissive type, a reflective type, a semi-transmissive type, and an external light / illumination type liquid crystal display device.

The above-mentioned characteristics are based on the fact that the point light source arranged in the missing portion can make the surface of the entire cell substrate emit light uniformly and the use of the linear light source is omitted. Incidentally, in order to obtain a linear light source from a point light source such as a light emitting diode, a linearization means is required, and the accommodation space is enlarged. Further, in the method of arranging the point light source in the center of the side surface of the cell substrate, it is difficult for light to be transmitted to both end portions on the arrangement side and it becomes dark, resulting in surface emission with a large difference in brightness.

In view of the above, even in the method of arranging a plurality of point light sources on the side surface of the cell substrate at regular intervals, the transmitted light inside the substrate is refracted according to Snell's law, and for example, in the cell substrate having a refractive index of 1.5, ± Since the transmission angle is 41.8 degrees and the transmission is in a narrow range, the distance between the light sources becomes dark, and separate means such as diffusion is required to expand the transmitted light. This leads to inconvenience due to changes in light emission characteristics such as a decrease in the amount of light incident on the control layer.

According to the present invention, by arranging the point light sources at the corners of the cell substrate, the transmission angle required for uniform light emission is narrowed to ± 45 degrees, which is half the transmission angle of ± 90 degrees in the case of the side surface arrangement. The light emission can be made uniform by means of slightly enlarging to suppress the change of the light emission characteristic by the optical path control layer, and the emission characteristic advantageous for the illumination of the liquid crystal can be obtained. In that case, if the point light sources are simply arranged at the corners of the rectangle, the light is incident from two side surfaces having an inclination angle of 45 degrees with respect to the light rays, and the incidence efficiency of the light is reduced. The uniformity of surface emission is also reduced because the light is divided into two rays that are divided at the corners.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to the present invention has a rectangular transparent cell substrate forming a liquid crystal cell, and has a missing portion for arranging a point light source at one or more corners, and The substrate has a transparent layer having a refractive index lower than that of the substrate on the liquid crystal side and an optical path control layer on the outer side, and the optical path control layer causes the light in the direction of the substrate to enter the cell substrate through the missing portion. It is provided with an optical path changing slope which reflects in the liquid crystal direction in the cell.

An example of the above-mentioned liquid crystal display device is shown in FIGS. FIG. 1 shows an example of a transmissive liquid crystal display device.
Is an example of a liquid crystal display device of a reflection type or an external light / illumination type. 10 is a cell substrate on the back side, 20 is a cell substrate on the viewing side, 14 and 24 are transparent layers having a low refractive index, 30 is a liquid crystal, and 40
Is an optical path control layer, Z1 is an optical path conversion slope, and 51 is a point light source. In addition, 11 and 21 are transparent electrodes, 12 and 22 are alignment films, 15 and 25 are polarizing plates, 16 and 26 are retardation plates, and 17
Is a light reflecting layer also serving as an electrode, and 23 is a color filter.

The liquid crystal cell has a missing portion for arranging the point light source 51 at one or more corners of the rectangular transparent cell substrate 10 (20) forming the cell as shown in the figure. , The cell substrate 10 (20) has a transparent layer 14 (24) having a lower refractive index than the substrate on the liquid crystal side,
An optical path control layer 40 is provided on the outside, and the optical path control layer is provided with an optical path conversion slope (Z1) for reflecting the light in the substrate direction incident on the cell substrate through the missing portion to the liquid crystal direction in the liquid crystal cell. Any of these can be used, and the type thereof is not particularly limited.

Therefore, as shown in the examples of FIG. 1 and FIG.
Viewing side and back side cell substrates 10, 2 provided with 17, 21
0 is placed with their electrode sides facing each other, while the liquid crystal 3
It is possible to use various liquid crystal cells in which 0 is enclosed, such as a transmissive type, a reflective type, a semi-transmissive type, and an external light / illumination type. Reference numeral 31 in the drawing is a sealing material for enclosing the liquid crystal 30 between the cell substrates 10 and 20.

By the way, specific examples of the above-mentioned liquid crystal cell include twist type, non-twist type and guest host type such as TN liquid crystal cell, STN liquid crystal cell, vertical alignment cell, HZN cell, OCB cell based on the alignment form of liquid crystal. And ferroelectric liquid crystals, and those that utilize light diffusion.
The liquid crystal drive system may be an appropriate system such as an active matrix system or a passive matrix system.
The liquid crystal is usually driven by a pair of cell substrates 10 and 2 as shown in the drawing.
It is performed through electrodes 11, 17, and 21 provided inside 0.

In the above, transparent or opaque of the cell substrate and the electrode is properly used depending on the display type such as transmissive type, reflective type, and semi-transmissive type. By the way, in the transmissive type or the semi-transmissive type illustrated in FIG. 1, a transparent substrate provided with transparent electrodes 11 and 21 in order to allow the transmission of illumination light or display light is made of a cell substrate 10 on the viewing side and the back side. , 20 are formed.

On the other hand, in the case of the reflection type illustrated in FIG. 2, the cell substrate 20 on the viewing side is a transparent substrate provided with a transparent electrode 21 in order to allow transmission of illumination light, external light and display light. The cell substrate 10 on the back side must be formed by
Can be selectively used depending on whether or not it is necessary to transmit illumination light or the like.

For example, when the light reflecting layer 17 is provided in the liquid crystal cell as shown in FIG. 2, the cell substrate 10 on the back side is
It is not necessary to transmit illumination light or the like. Therefore, it may be a transparent substrate or an opaque substrate. On the other hand, when the light reflecting layer is provided outside the liquid crystal cell, the cell substrate 10 on the back side is formed of a transparent substrate because it is necessary to transmit illumination light and the like. In FIG. 2, the light reflection layer 17 also serves as an electrode.

The cell substrate can be formed of an appropriate material such as glass or resin. Above all, a transparent substrate is preferably made of an optically isotropic material from the viewpoint of suppressing the birefringence as much as possible and reducing the optical loss. Further, from the viewpoint of improving the brightness and display quality, it is preferable to use one having excellent colorless transparency such as a non-alkali glass plate with respect to a blue glass plate, and a resin substrate is preferable from the viewpoint of lightness and the like. The form of the cell substrate is generally a rectangular plate.

The thickness of the cell substrate is not particularly limited and can be appropriately determined according to the liquid crystal encapsulation strength and the size of the point light source to be arranged. Generally, 10 μm to 5 m in terms of balance between optical transmission efficiency and thinness and lightness.
m, especially 50 μm to 2 mm, especially 100 μm to 1 mm. The cell substrate used as an optical transmission substrate on which a point light source is arranged has a larger cross-sectional area in terms of incidence efficiency, transmission efficiency, and the like, and thus a thicker substrate is more preferable.

On the other hand, a cell substrate which is not used as a transmission substrate for incident light is more advantageous in terms of thinness and lighter weight.
Therefore, the thickness of the cell substrate on the viewing side and the thickness of the cell substrate on the back side may be the same or different. Note that the cell substrate may be the same thickness plate, or the thickness may be partially different such as a wedge shape in cross section for the purpose of improving the incident efficiency of the transmitted light on the slope of the optical path conversion due to the inclined arrangement of the optical path control layer. May be

Further, the cell substrates on the viewing side and the back side may have the same plane dimensions or may have different plane dimensions. Therefore, as in the example of FIGS. 1 and 2, the cell substrate 10 or 20 serving as an optical transmission substrate is provided on the entire side surface of one side or two sides on the side having the missing portion where the point light source 51 is arranged, or on the side surface portion near the missing portion. Alternatively, it may be in a state of protruding from the side surface formed by the other cell substrate 20 or 10. This is because even when the light incident on the cell substrate is difficult to be transmitted to the protruding portion, it is less likely to affect the uniform illumination of the liquid crystal layer, which is advantageous for the uniform illumination of the liquid crystal layer.

As shown in FIG. 3, a rectangular transparent cell substrate forming a liquid crystal cell has one or more corners α, β, γ, δ for the purpose of arranging the point light source 51. It is considered as missing. In the illustrated example, the corner portion α is a missing portion, and the point light source disposition surface η is formed on the cell substrate based on this. In the figure, A and B are front and back surfaces of the cell substrate,
C, D, E, and F indicate the sides of the rectangular cell substrate,
Z is a light emitting means having an optical path changing slope.

The missing portion can be formed by an appropriate method such as a cutting method. The shape of the above-mentioned point light source arrangement surface, which is the cell substrate surface formed by the missing portion, can be appropriately determined and is not particularly limited. Generally, it is a straight surface as illustrated in FIGS. 4 and 5 or a curved surface (concave surface) curved toward the substrate as illustrated in FIGS. The straight surface is excellent in ease of formation and shape stability, and the concave curved surface is advantageous in that the lens action enlarges the incident light from the point light source and improves the uniformity of transmitted light in the cell substrate. .

By the way, the convex curved surface opposite to the concave curved surface exhibits a lens effect of condensing the incident light from the point light source to narrow the transmission angle, and for example, the refractive index of the cell substrate is 1.5. , Then ± 41.8 on the above straight surface.
In contrast, the concave curved surface spreads more than that, and
On a convex curved surface, the angle is less than ± 41.8 degrees, and in particular, it is difficult for light to propagate near the two sides that form the corners where the cutouts are formed, and the uniformity of transmitted light deteriorates. It is preferable that the point light source arrangement surface is a smooth surface due to mirror finishing or the like from the viewpoint of light incidence efficiency, but with a fine uneven surface showing a light diffusion function for the purpose of expanding the transmission range of incident light. It may have been done.

The size of the point light source arrangement surface is appropriately determined according to the size and number of the point light sources to be arranged. Generally, from the viewpoint of workability of installing a point light source such as a light emitting diode, improvement of incident efficiency of divergent light, and even distribution of incident light in the direction of two sides adjacent to the missing portion, Missing length, L1 or L2 length is 0.3mm or more, especially 0.4mm or more, especially 0.5mm in the example of Figs.
It is above, and the total length of the two sides, in the above example, the length of (L1 + L2) is 1.0 to 50 mm, especially 1.2 to
It is 40 mm, particularly 1.5 to 30 mm.

The cell substrate forming the above-mentioned missing portion is appropriately used depending on the display type such as transmissive type, reflective type or semi-transmissive type. That is, in the transmissive type or the semi-transmissive type illustrated in FIG. 1, the missing portion is provided in the back side cell substrate 10, and in the reflective type illustrated in FIG. 2, the missing portion is provided in the visible side cell substrate 20. This is because light from a point light source is made incident through these cell substrates to achieve liquid crystal display.

The missing portions of the corners provided on the cell substrate may be provided at one location or at two to four locations. When a plurality of missing portions are provided, the combination of the corners can be appropriately determined such as adjacent corners, facing corners, or a combination thereof.

The cell substrate on which the missing portion is formed is shown in FIGS.
As in the above example, the transparent layer 14 or 24 having a lower refractive index than the substrate is provided on the side of the liquid crystal 30 of the substrate 10 or 20, and the optical path control layer 40 is provided outside the substrate.

The transparent layer having a low refractive index is provided as a layer having a refractive index lower than that of the cell substrate to which the transparent layer is attached.
As indicated by polygonal line arrows ψ1 and 2,
When the incident light from the inside of the cell substrate 10 or 20 is transmitted, the transmitted light is transmitted to the cell substrate 10 or 20 and the transparent layer 1.
4 or 24 through which the light is totally reflected and efficiently confined in the cell substrate, whereby the transmitted light is efficiently transmitted to the opposite side (rear) and the optical path control layer 40 at a position far from the point light source. The transmitted light is also supplied to the optical path conversion slope Z1 with good uniformity, and the optical path is converted to the liquid crystal 30 side through the reflection by the slope to show the brightness uniformity in the entire display screen as shown by the broken line arrows ω1 and ω2. The purpose is to improve. If the transparent layer with a low refractive index is not provided, the rearward transmission efficiency is poor, and the farther from the point light source, the darker the screen becomes and the display becomes difficult to see.

In the low refractive index transparent layer, the transmitted light is incident on the liquid crystal layer 30 and is subjected to birefringence and scattering, whereby the transmitted state is partially changed and the transmitted light is reduced. Prevents uneven display and darkens the display,
It is also intended to prevent the display in the vicinity of the point light source from becoming a ghost in the rear and deteriorating the display quality. Further, when the color filter 23 and the like are arranged, it is also an object to prevent abrupt attenuation due to absorption of the transmitted light due to the color filter 23 and to prevent the transmitted light from decreasing. JP-A-5-158033
In the case where the incident light from the light source is transmitted through the liquid crystal layer as in the liquid crystal display device taught by the publication, the transmitted light is scattered in the liquid crystal layer and becomes a non-uniform transmission state, resulting in non-uniformity of output light and ghost. And the displayed image is hard to see.

The transparent layer having a low refractive index is formed by a vacuum evaporation method or a spin coating method using an appropriate material such as an inorganic or organic low refractive index dielectric material having a lower refractive index than the cell substrate on which it is provided. It can be formed by a method of applying a suitable method such as the above and sintering it as necessary, and there is no particular limitation on the material and the forming method.

From the standpoint of the transmission efficiency to the rear due to the above-mentioned total reflection, the larger the difference in refractive index between the transparent layer and the cell substrate on which it is provided, the more advantageous it is. It is preferably 0.4. With such a difference in the refractive index, in the case of the dual-use type of external light / illumination, there is almost no effect on the display quality due to the reflection mode by external light. By the way, when the refractive index difference is 0.1, the reflectance of external light at the interface is 0.1% or less, and the decrease in brightness and contrast due to the reflection loss is extremely small.

The arrangement position of the transparent layer having a low refractive index can be appropriately determined, but from the viewpoints of the effect of confining the transmitted light and the prevention of invasion into the liquid crystal layer, the cell substrate 10 or 2 is provided as shown in the figure.
It is preferable to locate it between 0 and the transparent electrode 11 or 21. In addition, a color filter 2 is provided between the cell substrate and the transparent electrode.
In the case of disposing No. 3, from the viewpoint of preventing absorption loss of transmitted light due to the color filter, it is preferable to be located closer to the cell substrate side on which the color filter is provided than the color filter.

Therefore, the transparent layers 14 and 24 having a low refractive index are usually used.
Is preferably provided adjacent to the cell substrates 10 and 20. In that case, the smoother the surface of the substrate on which the transparent layer is attached, and thus the smoother the transparent layer is, the more advantageous in preventing the scattering of transmitted light, and the more preferable in terms of preventing the influence on the display light. From the above point, in the case of the transmissive type, it is generally preferable that the color filter 23 is located on the viewing side substrate 20 side as in the example of FIG.

If the thickness of the transparent layer having a low refractive index is too thin, the confinement effect described above may be diminished due to the phenomenon of wave bleeding. Therefore, it is more advantageous to maintain the total reflection effect. The thickness can be appropriately determined from the viewpoint of total reflection effect and the like, but in general, from the viewpoint of total reflection effect to visible light having a wavelength of 380 to 780 nm, particularly to light having a wavelength of 380 nm on the short wavelength side, the refractive index x 1/4 wavelength (95 nm) to 10 μm, especially 1/2 wavelength (190 nm) or more, especially 1 wavelength (380 nm) to 5 μm based on the optical path length calculated by layer thickness
The thickness is preferably 600 nm to 3 μm.
A thickness of m is preferred.

The transparent electrode provided on the cell substrate can be formed of an appropriate material in accordance with the related art such as ITO. When forming a liquid crystal cell, an alignment film made of a rubbing film for aligning the liquid crystal or the like, if necessary,
One or two or more suitable functional layers such as a color filter for color display can be provided. As shown in the drawing, the alignment films 12 and 22 are usually formed in contact with the liquid crystal 30, and the color filter 23 is usually provided between one of the cell substrates 10 and 20 and the transparent electrode. In the illustrated example, a color filter 23 is provided on the cell substrate 20 on the viewing side.

As shown by arrows ω1 and ω2 in FIGS. 1 and 2, the optical path control layer 40 is incident light into the cell substrate or transmitted light from the point light source 51 arranged at the missing portion of the cell substrate 10 or 20. It is intended to reflect the light in the direction of the substrate through the optical path conversion slope Z1 and change the optical path to the liquid crystal 30 side, that is, the viewing direction of the cell to be used as illumination light (display light).

Therefore, in the transmissive or semi-transmissive liquid crystal display device as shown in the figure, the optical path control layer 40 is arranged outside the cell substrate 10 on the back side so as to form a backlight mechanism, and is of a reflective type. In the liquid crystal display device, the front light mechanism is formed outside the cell substrate 20 on the viewing side. Further, the optical path control layer is arranged on the side opposite to the side on which the above-mentioned transparent layer having a low refractive index is provided in the cell substrate as shown in the figure.

As described above, by using the slope reflection type optical path control layer, the light in the regular reflection direction showing the peak due to the slope can be mainly used, and the optical path of the reflected light can be controlled to direct the display in an advantageous direction. In particular, a bright display can be achieved by providing directivity in the front (vertical) direction. In addition, even in a liquid crystal display device of both external light and illumination type, it is possible to easily balance the illumination light in a state advantageous to both modes by utilizing a flat portion other than the slope of the optical path control layer in a reflection mode by external light. it can.

In the above-mentioned scattering and reflection method via a rough surface, it is difficult to provide directivity, and the light emitted from the cell substrate is inclined more than the front direction, and the display in the front direction becomes dark. Further, it is difficult to balance the illumination light in both modes in the external light / illumination dual type.

The optical path control layer can be formed in an appropriate shape except that it has the above-mentioned optical path conversion slope. From the point of obtaining display light having excellent directivity in the front direction through optical path conversion or the like, it is based on an optical path control layer having an optical path conversion slope Z1 facing a missing portion in which a point light source is arranged, particularly based on prismatic irregularities. An optical path control layer having an optical path conversion slope Z1 is preferable.

The optical path control layer is preferably formed by arranging a plurality of light emitting means Z having an optical path converting slope Z1 as shown in the figure from the viewpoint of thinning, and further provided on the cell substrate. It is preferably formed as a layer having a higher refractive index than the transparent layer having a low refractive index. When the refractive index of the optical path control layer is lower than that of the transparent layer, the incident light from the point light source to the cell substrate or its transmitted light is easily confined in the substrate, and the incidence on the optical path control layer is hindered and displayed. It becomes difficult to use it as light.

As an example of the light emitting means having the above-mentioned optical path changing slope or the prism-shaped concavo-convex, there may be mentioned one having a convex portion or a concave portion having a cross section of a trigonal pentagon or the like. The convex portion or the concave portion may have two or more optical path conversion slopes Z1 based on an isosceles triangle or the like as in the example of FIG. 8, or as shown in the example of FIG. It may have a steep slope with a larger inclination angle or a gentle slope with a smaller inclination angle. The convex portion means a protrusion, and the concave portion means a groove. Further, a polygon such as a triangle is not strictly defined, and it is permissible to round the corners or bend the sides due to manufacturing errors or the like.

Therefore, as in the above example, the light emitting means is
It can be formed on a convex portion or a concave portion that is an equilateral surface or a slope having the same inclination angle, or can be formed on a convex portion or a concave portion that is formed by an optical path conversion slope and a steep slope or a gentle slope or a slope having a different inclination angle. The form can be appropriately determined by the number and position of the missing portions. From the viewpoint of maintaining the slope function by improving scratch resistance, it is advantageous that the slope is less likely to be scratched because the light emitting means is formed of concave portions rather than convex portions.

The light path control layer 40 or the light emitting means Z, which is preferable from the viewpoint of achieving good display quality by changing the light path of the light in the substrate direction with good vertical directivity to the liquid crystal cell, is the reference plane (virtual horizontal plane) of the cell substrate. ) With an inclination angle of 35-48
The optical path changing slope Z1 having a degree is provided facing the missing portion. Therefore, when arranging the point light sources in two or more missing portions, two or more optical path conversion slopes Z are provided corresponding to the number and the position.
An optical path control layer having 1 or a means for emitting light is preferably used.

The above-mentioned optical path changing slope Z1 reflects the light incident on the surface Z1 of the incident light from the missing portion through the point light source or the transmitted light to change the optical path to the liquid crystal side in the cell. Play a role of supply. In that case, the optical path conversion slope Z1
By setting the inclination angle of 35 to 48 degrees with respect to the reference plane, as shown by the broken line arrows ω1 and 2 in FIGS. It is possible to efficiently obtain display light that is converted and has excellent directivity to the front.

When the inclination angle is less than 35 degrees, the optical path of the reflected light is largely deviated from the front direction, and the light is usually emitted in an oblique direction exceeding 30 degrees and is difficult to be effectively used for display, resulting in poor brightness in the front direction. If it exceeds 48 degrees, the leak light from the optical path conversion slope becomes larger than the condition for totally reflecting the incident light or the transmitted light, and the light utilization efficiency of the incident light becomes poor. The preferable inclination angle of the optical path conversion slope Z1 from the viewpoints of optical path conversion with excellent directivity to the front and suppression of leaked light takes into consideration total reflection conditions based on refraction according to Snell's law of light transmitted in the cell substrate. It is 38 to 45 degrees, especially 40 to 44 degrees.

Light emitting means Z having an optical path changing slope Z1
Is usually formed for the purpose of thinning as described above, and is formed as an optical path control layer 40 in which a plurality of the layers are distributed as shown in the drawing. In that case, as shown by the polygonal line χ in FIG. 2, the incident light from the missing portion is reflected backward and is efficiently transmitted to the opposite side to emit light as uniformly as possible over the entire surface of the liquid crystal display. Inclination angle to the plane is 10 degrees or less, especially 5 degrees or less, especially 0 to
It is preferable to adopt a structure including a gentle slope of 3 degrees or a flat surface (the portion other than the light emitting means in the optical path control layer) having an inclination angle of approximately 0 degrees.

Therefore, in the light emitting means Z including the steep slope (the surface facing the optical path changing slope Z1) illustrated in FIG. 9, the steep slope has an angle of 50 degrees or more, preferably 60 degrees or more, particularly 70 to 9 degrees.
A structure in which the width of the flat surface can be widened to 0 degree is preferable. If such an inclination angle is large, the leaked light that is incident at an angle that cannot be totally reflected on the optical path conversion slope is re-injected into the optical path control layer through reflection on the steep slope, and the concave lens effect based on the shape causes It is possible to change the light into a light having a small transmission angle that is easily transmitted and is easily totally reflected on the slope of the optical path.

The above-mentioned gentle slope or flat surface is shown in FIG.
By arranging the light reflection layer on the back side (outer side) of the optical path control layer 40 in the transmission type illustrated in FIG. 1, the reflection light (display light) is transmitted through the incident portion of external light and the light reflection layer of the incident light. As a result, it is possible to perform display in a reflection mode by external light with the point light source turned off, and to form an external light / illumination type liquid crystal display device.

Further, in the case of the front-light type reflection type liquid crystal display device and the external light / illumination dual type liquid crystal display device illustrated in FIG. 2, the gentle slope or flat surface is the external light incident part and its incident light or illumination. It functions as a transmission part of the reflected light (display light) through the light reflection layer 17 of light, and is essential for achieving liquid crystal display.

Therefore, in the above-mentioned case, when the optical path control layer has the adjacent repeating structure of the light emitting means composed of the optical path conversion slope and the gentle slope, the angle difference of the inclination angle of the gentle slope with respect to the reference plane is taken as the entire optical path control layer. Within 5 degrees, within 4 degrees, especially within 0.1-3 degrees, and the difference in inclination angle between the nearest gentle slopes within 0.5 degrees, within 0.3 degrees, especially 0.0
It is preferable to set it to 01 to 0.1 degree. This does not significantly change the optimum viewing direction of the liquid crystal display device, in particular, the optimum viewing direction in the vicinity of the front direction due to the transmission of the gentle slope.
The purpose is not to make a large change between the nearest gentle slopes.

From the point of obtaining a bright display in the reflection mode, the projected area of the gentle slope with respect to the reference plane is 5 times or more, especially 10 times or more, of that of the optical path conversion slope Z1.
It is preferably ˜100 times. This is intended to improve the incidence efficiency of external light and the transmission efficiency of reflected display light through the light reflection layer.

The light emitting means Z may be formed continuously from one side to the opposite side of the optical path control layer, or may be intermittently formed discontinuously as shown in FIG. In the case of forming discontinuously, the length of the optical path conversion slope in the long side direction is 5 to 500 times the depth or height of the groove or the protrusion from the viewpoints of the incident efficiency of the transmitted light and the optical path conversion efficiency. ˜200 times, and particularly preferably 10 to 100 times. From the viewpoint of uniform light emission of the liquid crystal display surface, the length of the optical path conversion slope in the long side direction is 500 μm or less, preferably 10 to 400 μm, especially 30 to 3 μm.
It is preferably set to 00 μm.

The arrangement of the plurality of light emitting means forming the optical path control layer can be appropriately determined. For example, the long side direction of the optical path conversion slope is arranged so as to be parallel or inclined to the missing portion where the point light source is arranged. However, the light emitting means is arranged so that the long side direction of the optical path conversion slope faces as shown in the example of FIG. 3 rather than the point that the radial incident light from the point light source is dealt with and the surface emission is performed with good uniformity. Further, it is preferable that the optical path control layer is arranged concentrically with respect to the virtual center at the missing portion, particularly with respect to the point light source.

In the above description, the arrangement pitch of the light emitting means is not particularly limited. Since the optical path conversion slope becomes a factor that determines the brightness in the illumination mode, the light emission uniformity on the liquid crystal display surface, and for both external light and illumination type, depending on the uniformity of the light emission on the liquid crystal display surface in the reflection mode, etc. It can be determined, and the light quantity for changing the optical path can be controlled by the distribution density.

Therefore, the light emitting means and the inclination angle of the optical path conversion slope forming the light emitting means may have a constant shape over the entire surface of the optical path control layer, or may cause absorption loss or attenuation of transmitted light due to the previous optical path conversion. For the purpose of coping with the uniform emission of light on the liquid crystal display surface, the light emitting means may be made larger as the distance from the missing portion increases as illustrated in FIG. Further, the light emitting means may have a constant pitch, or as shown in FIG. 9, the pitch may be gradually narrowed as the distance from the missing portion is increased to increase the distribution density of the light emitting means Z. Further, the light emission on the liquid crystal display surface can be made uniform with a random pitch.

In addition, in the case where the light emitting means has irregularities formed by discontinuous grooves or protrusions, the irregularities in the size and shape of the irregularities, the distribution density, the direction of the ridges, or the like can be used. It is also possible to uniformly arrange light emission on the liquid crystal display surface by arranging regularly or uniformly irregularities. Therefore, uniform emission of light on the liquid crystal display surface as in the above-described example can be achieved by applying an appropriate method to the light emitting means. In FIGS. 8 and 9, the arrow direction is the transmission direction of the incident light from the missing portion.

When a liquid crystal display device of a reflection type or an external light / illumination type is used, if the optical path conversion slope of the light emitting means overlaps the pixel of the liquid crystal cell, the display light is insufficiently transmitted, resulting in an unnatural display. In some cases, the overlap area is preferably made as small as possible rather than the point of preventing it so as to secure a sufficient light transmittance through the gentle slope or the flat surface.

From the above point, considering that the pixel pitch of the liquid crystal cell is generally 100 to 300 μm, the optical path conversion slope is 1 to 40 based on the projection width to the reference plane.
The thickness is preferably 3 to 20 μm, especially 5 to 15 μm. Such a projection width is more preferable than the point that the deterioration of display quality due to diffraction is prevented because the coherent length of the fluorescent tube is generally about 20 μm.

On the other hand, it is preferable that the distance between the light path changing slopes is larger than the above point, but on the other hand, the light path changing slope is a functional portion for substantially forming illumination light by changing the light path of the missing portion incident light as described above. Therefore, if the interval is too wide, the illumination at the time of lighting may be sparse, resulting in an unnatural display. Considering these, the distribution pitch of the optical path conversion slope is 2
mm or less, preferably 20 μm to 1 mm, especially 50 μm to 0.5 mm.

Further, the distribution pattern of the light emitting means may interfere with the pixels of the liquid crystal cell to cause moire. The moire can be prevented by adjusting the distribution pitch of the light emitting means, but as described above, the pitch has a preferable range. Therefore, a solution when moire occurs in the pitch range becomes a problem. In the present invention, it is preferable to arrange the light emitting means in a crossing state with respect to the pixels to prevent moire.

In the above case, if the inclination angle of the light emitting means is too large, the reflection through the optical path converting slope is deflected, and a large deviation occurs in the direction of optical path conversion, which is likely to cause a deterioration in display quality. The inclination angle is preferably within ± 30 degrees, and more preferably within ± 25 degrees. The irregular arrangement of the light emitting means with a random pitch or the like is also effective for preventing moire.

The optical path control layer can be formed by an appropriate method. By the way, as an example, a method of transferring a shape by pressing a transparent film made of a thermoplastic resin under heating to a mold capable of forming a predetermined light emitting means, a heat-melted thermoplastic resin or heat or a solvent is used. A method of filling a fluidized resin into a mold capable of forming a predetermined light emitting means, a liquid resin capable of being polymerized by heat, ultraviolet rays, or radiation such as an electron beam, a monomer, an oligomer or the like is used as a predetermined light emitting means. There is a method in which a mold capable of forming is filled or cast and polymerized.

Further, a transparent resin is coated with a liquid resin, a monomer, an oligomer or the like which can be polymerized by radiation such as heat, ultraviolet rays or electron rays, and the coating layer is formed into a mold capable of forming a predetermined light emitting means. A method of pressing and molding followed by polymerization treatment, filling the liquid resin or the like into a mold capable of forming a predetermined light emitting means, and arranging a transparent film in close contact on the filling layer and irradiating with ultraviolet rays or radiation. A method of performing a polymerization treatment may also be used. In that case, the transparent film can be adhered and integrated with the formed optical path control layer, or can be separated, and at that time, the transparent film need not be a transparent film.

Therefore, the optical path control layer can be formed by directly providing the cell substrate or the like with a predetermined shape, or can be formed as a transparent sheet or the like having a predetermined shape. The thickness of the optical path control layer can be appropriately determined, but is generally 300 μm or less, especially 5 to 200 μ from the viewpoint of thinning.
m, especially 10 to 100 μm.

The optical path control layer is provided on the cell substrate because the incident light from the point light source or its transmitted light is efficiently incident on the optical path control layer from the cell substrate to achieve a bright display through the optical path conversion slope. It is preferable that the optical path control layer has a refractive index difference of 0.15 or less, particularly 0.10 or less, particularly 0.05 or less, and particularly, a refractive index higher than that of the cell substrate.

The optical path control layer suppresses the amount of lost light that is confined in the cell substrate due to interface reflection and cannot be emitted, and efficiently supplies the missing portion incident light or its transmitted light to the optical path control layer, especially to the optical path conversion slope. From the point, as in the case of the cell substrate, the refractive index is 0.05 or more than that of the low refractive index transparent layer,
Above all, it is preferably 0.08 or more, and particularly preferably 0.1 to 0.4.

As shown in FIGS. 1 and 2, the optical path control layer should be arranged with the surface having the light emitting means Z on the outside so that the reflection efficiency via the optical path conversion slope Z1 and the effective use of the light incident on the missing portion can be improved. It is more preferable in terms of improving the brightness. When the optical path control layer is independently formed as a transparent sheet or the like as described above, the transparent sheet or the like is 0.05 or more, more preferably 0.08 or more, as compared with the transparent layer 14 having a low refractive index as shown in FIG. ,
In particular, it is more preferable to adhere to one side of the liquid crystal cell via the adhesive layer 18 having a high refractive index of 0.1 to 0.4 from the above points. The adhesive layer has a refractive index difference of 0.
It is preferably 15 or less, more preferably 0.10 or less, particularly 0.05 or less, and particularly preferably a refractive index higher than that of the cell substrate. Further, such an adhesive layer can be provided in advance on a transparent sheet or the like.

Therefore, the refractive index of the adhesive layer can be the same as that of the above-mentioned optical path control layer. The adhesive layer can be formed with an appropriate transparent adhesive, and the type of the adhesive is not particularly limited. The adhesive method using an adhesive layer is preferable from the viewpoint of simplicity of the adhesive treatment work. For forming the adhesive layer, for example, an adhesive agent having a base polymer of an appropriate polymer such as rubber type, acrylic type, vinyl alkyl ether type, silicone type, polyester type, polyurethane type, polyether type, polyamide type, styrene type, etc. Can be used.

Above all, those having excellent transparency, weather resistance, heat resistance and the like, such as an acrylic pressure-sensitive adhesive having a base polymer of a polymer mainly composed of an alkyl ester of acrylic acid or methacrylic acid, are preferably used. In the adhesive layer such as the adhesive layer, for example, inorganic particles which have an average particle diameter of 0.5 to 20 μm and which may be conductive such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc. Alternatively, one or more kinds of appropriate transparent particles such as organic particles made of crosslinked or uncrosslinked polymer may be blended to form a light diffusion type adhesive layer.

An illumination mechanism functioning as a backlight or a front light in a liquid crystal display device has a point light source arranged at least at one of the missing portions provided on the cell substrate,
It can be formed by making the light from the light source enter the cell substrate. This makes it possible to provide a thin and lightweight liquid crystal display device that illuminates the liquid crystal in the cell in cooperation with the optical path control layer. As the point light source, an appropriate one such as a light emitting diode can be used.

The point light source enables visual recognition in the illumination mode by turning on the light, and in the case of an external light / illumination type liquid crystal display device, it is necessary to turn on the light in the reflection mode by external light. Since there is no light, it is possible to switch the light on and off. As the switching method, any method can be adopted, and any conventional method can be adopted. The point light source to be arranged may be of a different color light emission type capable of switching the emission color, or may be one capable of emitting different color light via different point light sources.

The point light source may be a combination body in which an appropriate auxiliary means such as a reflector is arranged to guide the divergent light into the cell substrate, if necessary. As the reflector, a suitable reflection sheet that reflects light, such as a resin sheet provided with a metal thin film having high reflectance, a white sheet or a metal foil, may be used.

A liquid crystal display device generally comprises a liquid crystal cell functioning as a liquid crystal shutter, a driving device associated with the liquid crystal cell, a front light or a back light, and optional components such as a light reflection layer, a polarizing plate, and a retardation plate for compensation. Are formed by appropriately assembling. In the present invention, there is no particular limitation except that a point light source is arranged in the above-mentioned missing portion of the liquid crystal cell to form an illumination mechanism, and it is formed according to a conventional front light type or backlight type. You can Therefore, it is possible to form an appropriate liquid crystal display device such as a transmissive type, a reflective type, a semi-transmissive type, or an illumination / external light type.

Incidentally, the transmissive liquid crystal display device has the cell substrates 10 and 2 on the viewing side and the back side of the liquid crystal cell as in the example of FIG.
0 is a transparent substrate having a transparent electrode, and the cell substrate on the back side thereof is provided with the above-mentioned missing portions and the like. Polarizing plates can be formed on both the viewing side and the back side of the liquid crystal cell as necessary. 15, 25 are arranged. In that case, by providing a light reflecting layer on the back side (outer side) of the optical path control layer, light leaking from the optical path conversion slopes can be reflected and returned to the direction of the liquid crystal cell, which can be used for cell illumination, thereby improving the brightness. Can be planned.

In the above case, by using the light reflection layer as a diffusive reflection surface, the reflected light can be diffused and directed in the front direction, and can be directed in an effective direction by visual recognition. Further, by providing the above-mentioned light reflection layer, it can be used as a transmissive liquid crystal display device for both external light and illumination.

The reflection type liquid crystal display device can be formed by using the cell substrate on the viewing side of the liquid crystal cell provided with the above-mentioned missing portions as shown in the example of FIG. The polarizing plate 25 is arranged on the back side and / or. In that case, it is common to arrange the optical path control layer 40 on the viewing side as shown in the figure to form a front-light type liquid crystal display device.

In the reflection type liquid crystal display device, the arrangement of the light reflection layer is essential. The arrangement position can be provided inside the rear substrate 10 in the liquid crystal cell as illustrated in FIG. 1 or outside the liquid crystal cell. Therefore, in the example of FIG. 1, the light reflection layer 17 also serves as an electrode. The reflection type liquid crystal display device according to the present invention can be generally used as an external light / illumination type. When a light reflecting layer is provided on the outer side of the back side of the liquid crystal cell, a polarizing plate can be arranged between the light reflecting layer and the liquid crystal cell as necessary.

In the above description, the light reflecting layer is, for example, a coating layer containing a powder of a high reflectance metal such as aluminum, silver, gold, copper or chromium in a binder resin, or an attached layer of a metal thin film by a vapor deposition method or the like. The coating layer or the additional layer can be formed as an appropriate light-reflecting layer according to a conventional method such as a reflecting sheet having a base material supported thereon, a metal foil, a transparent conductive film, or a dielectric multilayer film.

On the other hand, a semi-transmissive liquid crystal display device can be formed by forming the light-reflecting layer in the above-mentioned reflective type into a semi-transmissive reflective layer that reflects and transmits light. In that case, the optical path control layer may be disposed on the viewing side of the liquid crystal cell, but is generally preferably disposed on the back side. Therefore, it is preferable to comply with the case of the transmission type including the arrangement of the polarizing plate.

The semi-transmissive liquid crystal display device can be used as an external light / illumination type device. Further, according to the above-mentioned transmission type, when the liquid crystal cell has an optical path control layer on the outer side of the back side, the light reflecting layer is arranged on the back side (outer side) of the layer to further improve the brightness. You can This is because it is possible for light that has passed through the semi-transmissive reflective layer or is reflected by the semi-transmissive reflective layer to reach the back surface of the liquid crystal display device to be reflected and inverted by the light reflective layer and re-enter the liquid crystal cell. .

The semi-transmissive reflective layer is a suitable system such as a system in which the above-mentioned light reflective layer reflects and transmits light like a half mirror, or a system in which an opening for light transmission is provided in the light reflective layer. Can be done at. The openings are preferably distributed so as to correspond to the pixels of the liquid crystal cell.

In the above-mentioned transmissive type or semi-transmissive type, and further in the reflective type in which a light reflection layer is arranged outside the liquid crystal cell, the cell substrate or electrode has a transparent substrate or a transparent substrate in order to enable liquid crystal display. It is necessary to form it as a material that can transmit light, such as an electrode.

In the liquid crystal display device, as shown in the examples of FIGS. 1 and 2, one or more suitable optical layers such as polarizing plates 15 and 25, retardation plates 16 and 26, and a light diffusing layer are added to the liquid crystal cell. It may be one. In that case, those optical layers may be applied as an optical member integrated with the optical path control layer.

The above-mentioned polarizing plate is intended to achieve display utilizing linearly polarized light, and the retardation plate is intended to improve display quality by compensating for retardation due to birefringence of liquid crystal.
In addition, the light diffusion layer expands the display range by diffusing the display light, equalizes the brightness by leveling the bright line emission through the optical path conversion slope of the optical path control layer, and the optical path control layer by diffusing the transmission light in the cell substrate. The purpose is to increase the amount of incident light on the.

As the polarizing plate, an appropriate one can be used without any particular limitation. From the viewpoint of obtaining a good contrast ratio display due to the incidence of highly linearly polarized light, it is more hydrophilic than those such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film. There is a high degree of polarization such as an absorptive polarizing film made by adsorbing and stretching a dichroic substance such as iodine or a dichroic dye on a molecular film or a film having a transparent protective layer on one or both sides thereof. It can be preferably used.

In forming the transparent protective layer, those having excellent transparency, mechanical strength, thermal stability and moisture shielding property are preferably used. Examples include acetate-based resins and polyester-based resins, polyethersulfone-based resins and polycarbonate-based resins, polyamide-based resins and polyimide-based resins, polyolefin-based resins and acrylic-based resins, polyether-based resins, polyvinyl chloride, and styrene-based resins. Examples thereof include polymers such as and norbornene resins, and thermosetting or ultraviolet curing resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone resins. The transparent protective layer can be provided by an adhesive method of a film or a coating method of a polymer liquid or the like. Therefore, the above-mentioned optical path control layer or transparent sheet can be used as a transparent protective layer.

The polarizing plate to be used, particularly the polarizing plate on the viewing side, has been subjected to a non-glare treatment or an antireflection treatment for the purpose of preventing visual inhibition due to the surface reflection of external light, and a hard coat treatment for the purpose of preventing scratches. May be Non-glare treatment can be performed by making the surface a fine concavo-convex structure by various methods such as a roughening method such as a sandblasting method or an embossing method, a mixing method of transparent particles such as silica, and the antireflection treatment is It can be applied by a method of forming an interfering vapor deposition film.

Further, the hard coat treatment can be performed by a method of coating a hard resin such as a curable resin. Further, the non-glare treatment, the antireflection treatment, and the hard coat treatment can be carried out by the above-mentioned method of adhering a film provided with the surface fine uneven structure or the interference film. The polarizing plates may be provided on both sides of the liquid crystal cell as shown in the figure, or may be provided on only one side of the liquid crystal cell. The non-glare treatment, antireflection treatment, and hard coat treatment described above can also be applied to the light emitting means forming surface of the optical path control layer.

On the other hand, as the retardation film, a birefringent film or a nematic film obtained by subjecting a film made of a suitable polymer such as those exemplified in the above-mentioned transparent protective layer to a stretching treatment by a suitable method such as uniaxial or biaxial. An appropriate film such as an alignment film of an appropriate liquid crystal polymer such as a liquid crystal system or a discotic system, or an alignment film in which the alignment layer is supported by a transparent substrate can be used, and the thickness of the heat shrinkable film can be increased under the action of the heat shrinkage force. For example, the refractive index in the vertical direction may be controlled.

The retardation plates 16 and 26 for compensation are usually disposed between the polarizing plates 15 and 25 on the viewing side and / or the back side and the liquid crystal cell as necessary as shown in the figure, and the retardation plates are provided on the retardation plates. May be appropriately selected depending on the wavelength range and the like. Further, the retardation plate may be used by superposing two or more layers for the purpose of controlling optical characteristics such as retardation.

The light diffusing layer can also be provided by an appropriate method using a coating layer or a diffusing sheet having a surface fine uneven structure according to the non-glare layer. The light diffusing layer can be formed as a pressure-sensitive adhesive layer containing transparent particles and also as a layer that also serves as an adhesive for a polarizing plate and a retardation plate, thereby making it possible to reduce the thickness.

According to the liquid crystal display device of the present invention, most of the incident light from the missing portion is transmitted rearward through the cell substrate through reflection according to the law of refraction, and emission (leakage) from the substrate surface is prevented. Meanwhile, the optical path conversion slope Z of the optical path control layer
The light incident on 1 is efficiently and vertically redirected in the viewing direction with good directivity, and the other transmitted light is further transmitted backward by total reflection and is incident on the rearward optical path conversion slope Z1 to be efficiently vertically directed in the viewing direction. It is possible to achieve a display with excellent uniformity of brightness on the entire surface of the liquid crystal display surface by performing optical path conversion with good performance. Therefore, it is possible to form a liquid crystal display device of a transmissive type, a reflective type, a semi-transmissive type or an external light / illumination dual type which is bright and easy to see and is excellent in display quality by efficiently utilizing light from a point light source.

In the external light / illumination type liquid crystal display device conforming to the transmission type illustrated in FIG. 1 described above, the visual confirmation is that in the illumination mode by turning on the light source, the optical path conversion slope of the optical path control layer arranged on the back side is observed. The light reflected at is incident on the liquid crystal cell, and the display light transmitted through the polarizing plate on the viewing side is visually recognized. Further, in the external light mode by turning off the light source, the external light incident from the viewing side surface passes through the liquid crystal cell to reach the optical path control layer on the back side, and the light incident from the part other than the light emitting means is provided on the back surface. The display light which is inverted through the light reflection layer and transmitted through the inside of the liquid crystal cell in the opposite direction is visually recognized.

On the other hand, in the reflection type liquid crystal display device illustrated in FIG. 2, visual recognition by both external light and illumination is emitted from the back surface of the optical path control layer 40 as indicated by an arrow ω2 in the illumination mode by turning on the light source 51. After the light is reflected by the light reflection layer 17 via the liquid crystal cell, it travels backward in the liquid crystal cell to reach the optical path control layer, and the display light transmitted through the portion other than the light emitting means Z is visually recognized.

On the other hand, in the external light mode in which the light source is turned off, the light incident from the portion other than the light emitting means in the optical path control layer passes through the light reflecting layer 17 and reversely travels in the liquid crystal cell in the same manner as described above to control the optical path. The display light which reaches the layer and is transmitted from the portion other than the light emitting means is visually recognized.

On the other hand, in the semi-transmissive liquid crystal display device, the visual recognition by both external light and illumination is based on the transmitted light and / or the reflected light through the semi-transmissive reflective layer, based on the transmissive liquid crystal and / or the reflective liquid crystal. According to the display device, visual recognition of the display light in the illumination mode or the external light mode is achieved.

In the present invention, the optical elements or parts such as the optical path control layer, the liquid crystal cell, the polarizing plate and the retardation plate which form the above-mentioned liquid crystal display device are integrally or integrally laminated and fixed. Alternatively, they may be arranged in an easily separable state. The fixed state is preferable from the standpoint of preventing the reduction of the contrast by suppressing the interface reflection. An appropriate transparent adhesive such as a pressure-sensitive adhesive can be used for the fixing and adhesion treatment, and the transparent adhesive layer can be made to contain the above-mentioned transparent particles or the like to form an adhesive layer having a diffusion function.

The above-mentioned optical elements or parts, especially those on the viewing side, are treated with an ultraviolet absorber such as salicylate compound, benzophenone compound, benzotriazole compound, cyanoacrylate compound, nickel complex salt compound or the like. For example, it is possible to have an ultraviolet absorbing ability.

[0100]

EXAMPLES Example 1 Width 27 mm, Length 36 mm, Thickness 0.7 mm, Refractive Index 1.52
Vacuum-deposited magnesium fluoride on a non-alkali glass plate to form a low-refractive-index transparent layer with a thickness of 600 nm and a refractive index of 1.38, and a red, blue, and green stripe-shaped color filter layer, ITO. After forming transparent electrodes in order and cutting the upper left corner at 45 degrees with notches on both sides of 0.7 mm, spin coat polyvinyl alcohol solution on it and rub the dried film to make it visible. A cell substrate was obtained. On the other hand, similar to the above, width 25mm, length 34mm, thickness 0.7mm
Aluminum was vapor-deposited on the non-alkali glass plate to form a light reflecting layer which also serves as an electrode, and a rubbing treatment film was provided thereon to obtain a back side cell substrate. The transparent electrode on the viewing side and the reflective electrode on the back side were divided by etching.

Then, the cell substrates on the visible side and the back side are opposed to each other with their rubbing surfaces facing each other so that the rubbing directions are orthogonal to each other, a gap adjusting material is arranged, and the periphery is sealed with an epoxy resin, and then a liquid crystal (manufactured by Merck). And a UV-curable resin are injected to expose the film to ultraviolet light, forming a liquid crystal cell that becomes cloudy when no electric field is applied and becomes transparent when an electric field is applied. A transparent sheet on which an optical path control layer is formed is adhered to the sheet with a polarizing plate, and a width of 25
A liquid crystal panel having a length of mm and a length of 34 mm was obtained. When forming the liquid crystal cell, both sides of the corner of the cell substrate where the missing portion was formed were protruded by 2 mm from the cell substrate on the back side. Next, a white light emitting diode was arranged and fixed to the missing portion of the viewing side cell substrate to obtain a reflective liquid crystal display device.

For the transparent sheet, a transparent film having a refractive index of 1.54 is coated with a UV-curable resin having a refractive index of 1.518 after curing, and the resin is allowed to stand on a mold previously formed into a predetermined shape. It was obtained by forming an optical path control layer by exposing it to ultraviolet rays and curing it. The optical path control layer is
The light emitting means consisting of a concave portion with a triangular cross-section having a length of about 100 μm and a width of about 10 μm, an optical path conversion slope with an inclination angle of about 41 degrees and a steep slope of about 75 ° C. has a width of 21 mm and a length of 30 mm in a rectangular range. It is irregularly distributed and the optical path conversion slopes are concentrically distributed with one corner portion of the rectangular range as a virtual center. The transparent sheet was adhered to the liquid crystal cell via an acrylic adhesive layer having a refractive index of 1.520 attached to the surface not having the optical path control layer and with the optical path conversion slope facing the missing part.

Example 2 Width 27 mm, Length 36 mm, Thickness 0.7 mm, Refractive Index 1.52
Vacuum-deposited magnesium fluoride on a non-alkali glass plate to form a low-refractive-index transparent layer with a thickness of 600 nm and a refractive index of 1.38, and an ITO transparent electrode was formed on it to form the upper left corner on both sides. After cutting at 45 degrees with a notch length of 0.9 mm,
A polyvinyl alcohol solution was spin coated thereon and the dried film was rubbed to obtain a back side cell substrate.
On the other hand, similar to the above, width 25 mm, length 34 mm, thickness 0.7
A red, blue, and green striped color filter layer and an ITO transparent electrode were sequentially formed on a non-alkali glass plate having a size of mm, and a rubbing treatment film was provided thereon to obtain a cell substrate on the visible side. The transparent electrodes on the viewing side and the back side were divided by etching.

Then, a liquid crystal cell was formed according to Example 1 using the above-mentioned viewing-side and back-side cell substrates, and polarizing plates were adhered to both sides thereof, and the same optical path control as in Example 1 was performed on the back side. A transparent sheet with a layer is adhered, and a white light emitting diode is arranged and fixed in the missing portion of the cell substrate on the back side of the transparent sheet with a width of 2
A transmissive liquid crystal display device having a length of 5 mm and a length of 34 mm was obtained. During the formation of the liquid crystal cell, both sides of the corner of the cell substrate where the missing portion was formed were projected by 2 mm from the cell substrate on the viewing side.

Comparative Example 1 A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that the cell substrate on the viewing side was not provided with a missing portion. The white light emitting diode was arranged at the protruding corner portion.

Comparative Example 2 A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that the low refractive index transparent layer was not provided on the cell substrate on the viewing side.

Comparative Example 3 Example 1 was repeated except that the size of the missing portion in the cell substrate on the viewing side was 2 mm on the left side and 0.2 mm on the upper side.
A reflective liquid crystal display device was obtained according to the above.

Comparative Example 4 A reflective liquid crystal display device according to Example 1 except that the size of the cutout portion on the viewing-side cell substrate was 0.3 mm (total 0.6 mm) on the left and upper sides. Got

Comparative Example 5 The cell substrate on the viewing side was not provided with a missing portion, and a white light emitting diode was arranged at the center of the upper side of the cell substrate.
A reflective liquid crystal display device was obtained in the same manner as in Example 1 except that a transparent sheet with an optical path control layer was bonded so that the light emitting diode became the virtual center of the optical path conversion slope.

Comparative Example 6 A transmissive liquid crystal display device was obtained in the same manner as in Example 2 except that the rear cell substrate was not provided with a missing portion. The white light emitting diode was arranged at the protruding corner portion.

Comparative Example 7 A transmissive liquid crystal display device was obtained in the same manner as in Example 2 except that the low refractive index transparent layer was not provided on the cell substrate on the back side.

Evaluation Tests Regarding the liquid crystal display devices obtained in Examples and Comparative Examples, the light emitting diode was turned on in a dark room with no voltage applied to the liquid crystal cell in the reflective type and in the transmissive type with voltage applied.
The front luminance at the center of the screen is measured by a luminance meter (Topcon Co., BM
-5).

The above results are shown in the following table. Front Brightness (cd / m ² ) Example 1 31 Example 2 52 Comparative Example 1 3 Comparative Example 2 6 Comparative Example 3 8 Comparative Example 4 8 Comparative Example 5 37 (Variation of Brightness) Comparative Example 6 5 Comparative Example 7 7

In the above, the bright and uniform display was achieved in Example 1, but the comparative example 1 was dark and non-uniform display, and the bright portion was within a range of about 60 degrees from the corner of the light source arrangement. The regions near the two corners on the left and right, which share a side with the corners of the light source arrangement, were very dark. In Comparative Example 2, only the vicinity of the light source was bright, and it became darker as it was farther from the light source, and uniform light emission was not obtained. In Comparative Example 3, only the upper side was bright and the left side was dark with almost no light emission. Further, in Comparative Example 4, the image is dark as a whole, especially in the vicinity of the upper side and the left side, and in Comparative Example 5 as well, the vicinity of the left and right corners of the upper side of the liquid crystal panel is also very dark, and the central portion is bright, resulting in large variations in brightness. It was
In Example 1, bright and uniform display was achieved even in the reflection mode by external light.

On the other hand, the transmissive type of Example 2 also achieved bright and uniform display, but in Comparative Example 6, it is bright only in a narrow area in the central portion and its surroundings are dark, and in Comparative Example 7, it is far from the light source. It became darker and darker than Example 2. As described above, in the present invention, a liquid crystal display device of a transmissive type, a reflective type, a semi-transmissive type or an external light / illumination dual type having a uniform brightness distribution by preventing absorption by a color filter through a low refractive index transparent layer. Can be formed, while aiming to reduce the thickness and weight by avoiding the light guide plate,
It can be seen that a liquid crystal display device with good display quality can be formed by the optical path control layer method.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of an example of a transmissive liquid crystal display device.

FIG. 2 is an explanatory cross-sectional view of an example of a reflection type (external light / illumination type) liquid crystal display device.

FIG. 3 is an explanatory plan view of a missing portion and an optical path control layer.

FIG. 4 is an explanatory plan view of a missing portion.

FIG. 5 is an explanatory perspective view of the missing portion.

FIG. 6 is an explanatory plan view of another missing portion.

FIG. 7 is a perspective explanatory view of the missing portion.

FIG. 8 is an explanatory side view of an example of an optical path control layer.

FIG. 9 is a side view illustrating another example of the optical path control layer.

[Explanation of symbols]

10, 20: Cell substrates 11, 21: Transparent electrodes 14, 24: Low-refractive-index transparent layer 17: Light reflecting layer also serving as an electrode 30: Liquid crystal 40: Optical path control layer (Z: light emitting means, Z1: optical path conversion slope) ) 51: Point light source α, β, γ, δ: Corner portion η: Point light source arrangement surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuki Nakano             Nittoden 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture             Within Kou Co., Ltd. (72) Inventor Ryoji Kinoshita             Nittoden 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture             Within Kou Co., Ltd. F-term (reference) 2H090 JA01 JA02 JA04 JA11 JA13                       JB02 JB03 JB12 JD00 LA11                       LA16                 2H091 FA23X FA23Z FA45X FA45Z                       FB02 FB07 FC17 GA01 LA03                       LA16 LA17 LA18 LA19

Claims (14)

[Claims] 1. A rectangular transparent cell substrate forming a liquid crystal cell has a missing portion for arranging a point light source at one or more corners, and the cell substrate is closer to the liquid crystal than the substrate. An optical path that has a transparent layer with a low refractive index and an optical path control layer on the outside, and the optical path control layer reflects the light in the substrate direction incident on the cell substrate through the missing portion to the liquid crystal direction in the liquid crystal cell. A liquid crystal display device comprising a conversion slope. 2. The liquid crystal display device according to claim 1, wherein the missing length of one side of the missing portion is 0.3 mm or more, and the total missing length of the two sides is 1 to 50 mm. 3. The reflection type liquid crystal display device according to claim 1, wherein the cell substrate having a missing portion is a viewing side substrate having a transparent electrode, and the back side substrate of the liquid crystal cell has a light reflecting layer. 4. The transmissive type according to claim 1, wherein the cell substrate having a missing portion is a back side substrate having a transparent electrode, and the viewing side substrate of the liquid crystal cell is a transparent substrate having a transparent electrode, or A semi-transmissive liquid crystal display device in which a rear substrate includes a semi-transmissive reflective layer that transmits and reflects light. 5. The liquid crystal display device according to claim 1, wherein a point light source is provided in at least one place of the missing portion. 6. The optical path control layer according to claim 1, which is a layer having a higher refractive index than the transparent layer having a low refractive index, and is inclined at an angle of 35 to 48 degrees with respect to the reference plane of the cell substrate. A liquid crystal display device having a plurality of optical path changing slopes. 7. The liquid crystal display device according to claim 6, wherein the optical path conversion slope is arranged so as to face the missing portion. 8. The liquid crystal display device according to claim 1, wherein the optical path changing slope is formed by a prism-shaped concave portion having a triangular cross section. 9. The liquid crystal display device according to claim 8, wherein the prism-shaped concave portion is a discontinuous groove, and the long side length of the optical path conversion slope is 5 to 500 times the groove depth. 10. The liquid crystal display device according to claim 8 or 9, wherein the optical path control layer is formed by arranging prism-shaped concave portions concentrically with respect to an imaginary center located in the missing portion. 11. The optical path control layer according to claim 1, wherein the optical path control layer is made of a transparent sheet having a higher refractive index than the transparent layer having a low refractive index, and the transparent sheet has a low refractive index transparent with the optical path control layer facing outside. A liquid crystal display device which is adhered to one side of a cell substrate through an adhesive layer having a refractive index higher than that of the layer. 12. The liquid crystal display device according to claim 1, wherein the cell substrate surface in the missing portion is a straight surface or a curved surface curved toward the substrate. 13. The liquid crystal display device according to claim 1, wherein the optical path control layer and the cell substrate having the optical path control layer have a refractive index higher by 0.05 or more than that of the transparent layer having a low refractive index. 14. The liquid crystal display device according to claim 1, wherein the transparent cell substrate in the liquid crystal cell is made of an optically isotropic material.