CN101251674A - Backlight device and transmissive display device - Google Patents

Abstract

Provided are a backlight device and a transmissive display device capable of irradiating in frontal and left-right directions. To this end, the first light source (2) is arranged on the end face side of the first light guide plate (1), and the light extraction side of the first light guide plate (1) is formed into a triangular shape on the side opposite to the first light guide plate (1). The first prism sheet (3) is arranged in a prism row. On the side opposite to the first prism sheet (3) of the first light guide plate (1), the second light source (4) is configured through the viewing angle adjustment film (5), and the light from the second light source (4) Controlled by the viewing angle adjustment film 5, so that the angular distribution of the light emitted from the second light source (4) is narrow, and has directivity on the normal direction of the outgoing surface (30) of the first prism sheet (3) .

Description

Backlight device and transmissive display device

technical field

The present invention relates to a backlight device excellent in illumination characteristics and a transmissive display device excellent in display characteristics.

Background technique

Disclosed is a display device having a configuration in which light sources are respectively arranged on two different light-incident end surfaces of a light guide plate, and double-sided prism lenses having triangular prism rows and cylindrical lens rows are arranged on the light-emitting surface side of the above-mentioned light guide plate. sheet, and a transmissive display panel is arranged on the light-emitting surface side of the above-mentioned prism sheet. In this display device, light from the light source is emitted from the transmissive display panel at angles respectively corresponding to left and right parallax, and is synchronized with the light source so that parallax images are alternately displayed on the transmissive display panel, thereby Stereoscopic display is possible (for example, refer to Patent Document 1).

Also disclosed is a liquid crystal display device using a liquid crystal display panel in which an image forming layer including a liquid crystal layer and a parallax barrier layer are provided via a transparent layer. In this liquid crystal display device, the distance between the image forming layer and the parallax barrier layer is adjusted to a distance suitable for dual image display through the above-mentioned transparent layer, and the image for the left observer formed on the above-mentioned image forming layer and The image for the observer on the right is guided to the observers on the left and the right by transmitted light passing through the parallax barrier, thereby enabling dual image display in which different images are displayed (for example, refer to Patent Document 2).

[Patent Document 1] International Publication No. 04/027492 Pamphlet (Page 1)

[Patent Document 2] Japanese Patent Laid-Open No. 2005-258016 (Page 1)

Although in the display device shown in Patent Document 1, as long as two different images are repeated and rewritten on the liquid crystal panel in synchronization with the lighting switching of the light sources respectively arranged on the two different light incident end faces of the light guide plate, Users who watch from the normal direction of the display surface to 15 degrees to the left and users who watch to the right 15 degrees respectively watch different images, but there is a problem when the main user is facing directly When the panel is displayed, there is a problem that two images are mixed in the front direction.

In addition, the liquid crystal display panel of Patent Document 2 is provided with a parallax barrier so that an image for a left observer and an image for a right observer are displayed on the pixel formation layer, and the light emitted from each image is guided to the left and right respectively. For observers on the side and the right side, there is a problem that the display angle is tilted, and it is difficult to use when facing the display panel. In addition, since the image forming layer is divided into left and right observers, the image becomes an image with half the number of pixels, and a part of the transmitted light is blocked by the parallax barrier, so the display becomes dark.

Contents of the invention

The present invention is made in order to solve the above problems, and its purpose is to obtain a backlight device capable of illuminating in the front direction and the left and right directions.

Another object is to obtain a transmissive display device capable of displaying bright images in the frontal direction and in the lateral direction.

The backlight device related to the present invention comprises: a first prism sheet having triangular prism rows on one face; There is directional light on the direction that the normal line direction of the exit surface is inclined, and is incident on the triangular shape prism column of the above-mentioned first prism sheet; And the second light source will have a direction on the normal line direction of the exit surface of the above-mentioned first prism sheet Light is incident on the triangular prism arrays of the first prism sheet.

Directional light is incident on the triangular prism row of the first prism sheet in a direction inclined with respect to the normal direction of the outgoing surface of the first prism sheet, and is reflected on the slope of the triangular prism row of the first prism sheet And exit to the front direction. In addition, light having directivity in the normal direction of the output surface of the prism sheet enters the triangular prism array of the first prism sheet, is refracted on the prism sheet, and exits from the prism sheet in the left and right direction. Through the above processing, it is possible to irradiate in the frontal direction and the left-right direction.

Description of drawings

FIG. 1 is a perspective view of a backlight device according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory view showing a transmission optical path of light from a light source in FIG. 1 .

FIG. 3 is a diagram showing a transmitted light path in a first prism sheet according to Embodiment 1 of the present invention.

4 is a characteristic diagram showing angular distributions of incident light and outgoing light on the first prism sheet of light from the first light source in Embodiment 1 of the present invention.

5 is a characteristic diagram showing angular distributions of incident light and outgoing light on the first prism sheet of light from the second light source in Embodiment 1 of the present invention.

FIG. 6 is an explanatory diagram of an illumination state of the backlight device according to Embodiment 1 of the present invention.

7 is a characteristic diagram showing the angular distribution of irradiated light of the backlight device according to Embodiment 2 of the present invention.

8 is a characteristic diagram showing the angular distribution of irradiated light in the backlight device according to Embodiment 2 of the present invention.

9 is a characteristic diagram showing the angular distribution of irradiated light in the backlight device according to Embodiment 2 of the present invention.

10 is a characteristic diagram showing the angular distribution of irradiated light in the backlight device according to Embodiment 2 of the present invention.

11 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

12 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

13 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

14 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

15 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

16 is a characteristic diagram showing an angular distribution of light emitted from a second light source in the backlight device according to Embodiment 3 of the present invention.

17 is a configuration diagram of a backlight device according to Embodiment 4 of the present invention.

18 is a perspective view of a backlight device according to Embodiment 5 of the present invention and a transmissive display device using the same.

FIG. 19 is a diagram showing a transmission light path of the backlight device in FIG. 18 and a transmission state of a transmission panel.

FIG. 20 is a schematic diagram showing an alignment state of liquid crystal molecules in an optical component according to Embodiment 5 of the present invention.

FIG. 21 is a schematic view showing an alignment state of a liquid crystal material in an optical member related to another backlight device according to Embodiment 5 of the present invention.

22 is a cross-sectional view of another first light guide plate according to Embodiment 5 of the present invention.

23 is a configuration diagram of a backlight device according to Embodiment 6 of the present invention and a transmissive display device using the same.

24 is a configuration diagram of a transmissive display device according to Embodiment 7 of the present invention.

25 is a configuration diagram of a transmissive display device according to Embodiment 8 of the present invention.

26 is an explanatory diagram of a display image formed by the transmissive display device according to Embodiment 8 of the present invention.

Detailed ways

Embodiment 1

FIG. 1 is a perspective view of a backlight device according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram showing a transmitted optical path of light from the light source in FIG. 1 , and is a cross-sectional view using a plane perpendicular to the ridgeline direction of the triangular prism array of the prism sheet.

The first light source 2 is arranged respectively on the different two end face sides of the first light guide plate 1, the first prism sheet 3 is set on the light extraction side (exit side) of the first light guide plate 1, and the first light guide plate 1 On the side opposite to the first prism sheet 3 , the second light source 4 is arranged with the viewing angle adjustment film 5 interposed therebetween. In addition, a light source control unit 6 is provided to perform brightness adjustment or blink switching of the lights from the first light source 2 and the second light source 4 .

As the first light source 2 according to the present embodiment, an LED or an electric lamp is generally used, and light emitted from the first light source enters the end surface of the first light guide plate 1 . In addition, as the second light source 4 according to this embodiment, a surface light source such as electroluminescence other than LEDs and lamps is used, and light emitted from the second light source enters the main surface of the first light guide plate 1 .

In addition, although at least one of the first light source 2 and the second light source 4 may be arranged, as shown in this embodiment, when the first light source 2 is arranged on two different end face sides of the first light guide plate 1, Alternatively, when a plurality of second light sources 4 are arranged, uniformity of brightness in the backlight surface and angular distribution of irradiated light can be realized symmetrically.

The first light guide plate 1 according to this embodiment has a rectangular side surface and a flat plate shape as a whole, and a concave-convex prism composed of a gently inclined obtuse angled slope of 5 degrees or less is formed on at least one of the upper and lower surfaces to extract light. Or wrinkle. The light incident on the end surface of the first light guide plate 1 from the first light source travels while repeating total reflection, and a part of the light hits the uneven surface of the corrugation for light extraction and exits from the first light guide plate 1 .

In addition, the direction of the ridges of the triangular prism rows of the first prism sheet 3 according to the present embodiment is substantially parallel to the incident end surface of the first light guide plate 1 for light from the first light source 2 . By making them parallel, the light emitted from the first prism sheet 3 can be easily made uniform within the surface of the first prism sheet 3 .

As the viewing angle adjustment film 5 according to this embodiment, for example, a light control film manufactured by Sumitomo 3M (Three Em) Co., Ltd. is used, and the angular distribution of light emitted from the second light source 4 is narrowed to control directivity. . In this embodiment, the light leaked downward from the first light guide plate is absorbed by the viewing angle adjustment film 5 , thereby preventing it from becoming stray light. By reducing stray light, less light is missed in the left and right directions when the first light source 2 is turned on.

In addition, the first prism sheet 3 according to the present embodiment is formed of, for example, a material with a refractive index of 1.5, and is arranged in a triangular prism row in which the ridgeline extends in a direction parallel to the end surface of the first light guide plate 1 on one surface. It extends in a direction perpendicular to the plane of the paper, and is provided so that the surface side facing the first light guide plate 1 serves as a triangular prism array. Light from the first and second light sources enters the triangular prism array and exits from the surface of the first prism sheet 3 opposite to the first light guide plate 1 , that is, the exit surface 30 of the first prism sheet 3 .

3 is a diagram showing the transmission optical path of light from the first and second light sources in the first prism sheet 3 related to the backlight device of the present embodiment, and is a film in which the vertex angle of the triangular prism array is 60 degrees. Example of triangle formation.

As shown in FIG. 3 , the light from the first light source 2 passes from the first light guide plate 1 as a direction inclined relative to the normal direction of the exit surface 30 of the first prism sheet 3 (hereinafter referred to simply as the normal direction). Directional light is emitted. This light a1 having directivity in the direction inclined with respect to the normal direction is incident from the slope 3b of the triangular-shaped prism row of the first prism sheet 3, and is reflected at the slope 3a of the triangular-shaped prism row. The emission surface 30 of the sheet 3 emits light a2 having directivity in the normal direction, thereby irradiating the front direction. In addition, the light from the second light source 4 passes through the viewing angle adjustment film 5 to control directivity, and becomes light b1 having directivity in the normal direction. The slope 3a of the triangular prism row of the prism sheet 3 is incident, refracts when incident on the slope 3a of the triangular prism row, from the outgoing surface 30 of the first prism sheet 3, as on the direction inclined with respect to the normal direction The directional light b2 is emitted, thereby irradiating the left and right directions.

In addition, in the first prism sheet 3, the light b2 from the second light source is refracted when it enters the slope 3a of the triangular prism array, and has an angle of β with respect to the normal direction. Under the situation that the half angle of the apex angle of the triangular prism row of the first prism sheet 3 is α, if set β≤α, then above-mentioned light b2 can go out on the left and right direction, and can not be in the triangular prism row and Reflection occurs on the slope 3b opposite to the slope 3a.

Fig. 4 shows that as shown in Fig. 2, the angular distribution of the incident light a1 incident on the first prism sheet 3 through the first light guide plate 1, and the incident light a1 exiting from the first prism sheet 3 are emitted from the first light source 2 and passed through the first light guide plate 1 The characteristic diagram of the simulation results when the angular distribution of the outgoing light a2 is simulated by the ray tracing method based on the Monte Carlo method. In the figure, the horizontal axis is the angle relative to the normal direction. On the paper of FIG. 2, the left side relative to the normal direction is negative and the right side is positive, and the vertical axis is the intensity of light expressed in arbitrary units.

Fig. 4 (a) is the angular distribution of the incident light a1 that emerges from the first light source 2 and is incident on the first prism sheet 3. Among the figures, the angular distribution shown by the solid line is formed by the first prism on the left side of the paper surface in Fig. 2 The angular distribution of the incident light generated by a light source 2, the angular distribution shown by the dotted line is the angular distribution generated by the first light source 2 on the right, and they are mirror images of each other. That is to say, the light emitted from the left and right first light sources 2 is light having an angular distribution of 60° to 80° relative to the normal direction and light a1 having an angular distribution of -80° to -60° from the first light source 2 . A light guide plate is incident on the first prism sheet 3 .

Fig. 4 (b) is the angular distribution of the outgoing light a2 when the incident light a1 incident on the first prism sheet 3 exits from the first prism sheet 3, it shows that it has an angular distribution at -20 degrees to 20 degrees with respect to the normal direction , and spotlights in the normal direction.

5 shows the angular distribution of the incident light b1 emitted from the second light source 4 and incident on the first prism sheet 3 as shown in FIG. The angle distribution is a characteristic diagram of the simulation result when the simulation is performed by the Monte Carlo method based on the ray tracing method. In the figure, the horizontal axis is the angle relative to the normal direction. On the paper of Figure 2, the left side relative to the normal direction is negative and the right side is positive. The vertical axis is the intensity of light, expressed in arbitrary units .

Fig. 5 (a) is the angular distribution of the incident light b1 that exits from the second light source 4 and is incident on the triangular-shaped prism row of the first prism sheet 3, for example makes it narrow by viewing angle adjustment film 5 so that relative to the normal direction It has an angle distribution from -35 degrees to 35 degrees, and controls directivity in the normal direction. Fig. 5 (b) is the angular distribution of the outgoing light b2 when the incident light b1 incident on the first prism sheet 3 exits from the first prism sheet 3, it shows that it is not outgoing in the normal direction, but with respect to the normal direction The beams are emitted separately in the left and right directions so as to have an angle distribution of -30 degrees or less and 30 degrees or more.

FIG. 6 is an explanatory diagram of an illumination state of the backlight device according to the present embodiment. From the outgoing light of backlight device 10, to the viewer's side exit, if suppose the distance of left eye 8a and right eye 8b when the viewer is in the opposite side is about 65mm, from the exit surface 30 of the first prism sheet 3 to the line of sight of the viewer If the distance is about 300mm, the angle 9a formed by the normal direction 9 of the emitting surface 30 and the straight line connecting the left eye 8a or the right eye 8b is about 6 degrees. In addition, when one of the observer's left and right eyes is facing each other, the other eye is in the directions of -12 degrees and 12 degrees.

According to the above description, the frontal direction in this specification refers to the left and right 12 degrees centered on the normal direction on the above-mentioned emitting surface 30, that is, the angle area including the angle range of -12 degrees to +12 degrees relative to the normal direction, The angle range deviated from the above-mentioned frontal direction is defined as the left-right direction.

Therefore, as described above, in the present embodiment, since the light having the angular distribution shown in FIG. It is converged, so the angle range (range of -12 degrees to +12 degrees relative to the normal direction) of the outgoing light that can be recognized by the observer in the front direction can be fully included, and the front direction is irradiated by the first light source 2 .

In addition, since the light with the angular distribution shown in FIG. 5(a) is bent by the first prism sheet 3 so as to have an angular distribution of -30 degrees or less and 30 degrees or more with respect to the normal direction, it is possible to deviate from the viewer's The angle range of the emitted light in which the front direction can be identified (the range of −12 degrees to +12 degrees with respect to the normal direction) is irradiated by the second light source 4 in the left and right directions.

Embodiment 2

Use the first prism sheet 3 that the apex angle of triangular prism row is respectively 70 degree, 65 degree, 60 degree or 55 degree, as incident light b1 from the second light source 4 incident to the first prism sheet 3, use in the normal direction Light having directivity and having an angular distribution between -35° and 35° with respect to the normal direction, that is, light having an angular distribution of 70° around the normal direction, is subjected to the same process as in the first embodiment. The simulation of the angular distribution of each outgoing light when the light of the first and second light sources is emitted on each of the above-mentioned first prism sheets 3 .

7 to 10 are the simulation results of the angular distribution of the outgoing light b2 emitted on each of the first prism sheets 3 in the case of using the first prism sheet 3 having triangular prism rows with different apex angles. , that is, the angular distribution of the irradiated light of the backlight device of this embodiment. In addition, in each figure, (a) is the simulation result of the angular distribution of the outgoing light a2 emitted after the light from the first light source 2 is incident on the first prism sheet 3, and (b) is from the second light source 4 incident to the first prism sheet 3. A simulation result of the angular distribution of the outgoing light b2 emitted after the prism sheet 3.

When the apex angle of the prism is 70 degrees, as shown in Figure 7(a), the irradiated light in the front direction has an angular distribution of -10 degrees to 10 degrees with respect to the normal direction of the irradiated surface, and the angular distribution is wide. Narrower, as shown in Figure 7(b), the irradiating light toward the left and right directions is distributed below -20 degrees and above 20 degrees, so any range between -20 degrees to -10 degrees and 10 degrees to 20 degrees becomes The darker range of angles where light is difficult to see is difficult for the observer to use.

In addition, in the cases where the apex angles of the prisms are 65 degrees (shown in FIG. 8 ) and 60 degrees (shown in FIG. 9 ), the aforementioned darker angle regions are considerably narrowed and improved. However, when the apex angle of the prism is 55 degrees (as shown in FIG. 10 ), a dip in brightness occurs in the front direction, and a darker dark line can be seen in the front direction.

From the above description, it can be seen that the apex angle of the prisms as the first prism sheet 5 is preferably 60° to 65°.

Implementation mode 3.

Using the first prism sheet 3 having a triangular prism array having an apex angle of 60 degrees in Embodiment 1, the light b1 incident on the first prism sheet 3 from the second light source 4 has directivity in the normal direction, and Relative to the normal direction at -20° to 20°, -30° to 30°, -35° to 35°, -40° to 40°, -45° to 45°, or -50° to 50° In the case of having an angular distribution, that is, having an angular distribution with a width of 40 degrees, 60 degrees, 70 degrees, 80 degrees, 90 degrees, and 100 degrees around the normal direction, the above-mentioned each Simulation of the angular distribution of each outgoing light b2 when the incident light b1 with angular distribution is emitted on the first prism sheet 3 .

11 to 16 are the simulation results of the angular distribution of the outgoing light b2 when the incident light b1 having the above-mentioned different angular distributions exits from the first prism sheet 3. In each figure, (a) is from the second light source 4 Angle distribution of the incident light b1 incident on the triangular prism row of the first prism sheet 3, (b) is the angle of the outgoing light b2 when the light b1 incident on the first prism sheet 3 is emitted from the first prism sheet 3 Distribution of simulation results.

As shown in Figure 15 (angle distribution on -45 degrees to 45 degrees) and Figure 16 (angle distribution on -50 degrees to 50 degrees), if the incident light incident on the first prism sheet 3 from the second light source 4 If the angle distribution of b1 is wider than -45 to 45 degrees relative to the normal direction, the leakage of the outgoing light b2 from the first prism sheet 3 to the front direction will increase. In addition, as shown in FIG. 11, if the angle distribution of the incident light b1 incident on the first prism sheet 3 from the second light source 4 is narrowed to a range of -20 degrees to 20 degrees or less, the light from the first prism sheet 3 The range of the angular distribution of the outgoing light b2 is also narrowed, and the brightness of the slope below -60 degrees and above 60 degrees will decrease, so the amount of irradiation in the left and right directions will decrease, and the range will also be narrowed.

Thereby, it can be known that the angle distribution of the incident light b1 as the triangular prism column of the first prism sheet 3 from the second light source 4 is incident, as shown in Figure 12 (angle distribution on -30 degrees to 30 degrees), Figure 13 (in -30 degrees). Angle distribution at 35° to 35°) as shown in FIG. 14 (angle distribution at -40° to 40°), light having a wide angular distribution of 60 to 80° with the normal direction as the center is optimal. In addition, light with the above-mentioned angular distribution can be obtained by appropriately combining a diffusion film and a viewing angle adjustment film.

Embodiment 4

In the backlight device according to Embodiment 4 of the present invention, light from the second light source is extracted as light having directivity in the normal direction through a prism sheet, instead of light from the second light source 4 in Embodiment 1. The light having directivity in the normal direction passes through the viewing angle adjustment film 5 and enters the first prism sheet 3 .

17 is a configuration diagram of a backlight device according to Embodiment 4 of the present invention.

In the backlight device of Embodiment 1, on the side opposite to the first prism sheet of the first light guide plate, a second prism sheet is provided with the viewing angle adjustment film 5 and the diffusion sheet 8 interposed therebetween. A second light guide plate is arranged on the opposite side of the first light guide plate. The second light source 4 is arranged on the end face side of the second light guide plate 11 , and the reflective sheet 9 is provided on the side of the second light guide plate 11 opposite to the second prism sheet 13 .

In the backlight device of this embodiment, the light coming out from the first light source 2 travels while repeating total reflection in the first light guide plate 1, and comes out from the first light guide plate 1, and passes through the triangular shape of the first prism sheet 3. The oblique surfaces of the prism columns emit light towards the front through reflection. In addition, the light that comes out from the second light source 4 is also the same as above, and is reflected on the slope of the triangular prism array of the second prism sheet 13 to emit toward the front direction, and the outgoing light that has directionality in the normal direction is incident on the second prism sheet 13. The triangular prism rows of the first prism sheet 3 are emitted from the first prism sheet 3 in the left-right direction as in the first embodiment.

In addition, the apex angles of the triangular-shaped prisms of the first and second prism sheets in the backlight unit of the present embodiment are both 60 degrees, the angular distribution of the light incident on the first prism sheet 3 and the light output from the first prism sheet 3 The simulation results of the angular distribution of light are the same as those in FIGS. 4 and 5 .

In addition, in the present embodiment, since light with high directivity in the normal direction is emitted from the second prism sheet 13 , there is an advantage that less light is absorbed by the viewing angle adjustment film 5 and the luminance efficiency is high.

Embodiment 5

18 is a perspective view of a backlight device according to Embodiment 5 of the present invention and a transmissive display device using the same. 19 is an explanatory view showing the transmitted light path of the backlight device in FIG. 18 and the transmitted state of the transmissive panel, using a cross-sectional view of a plane perpendicular to the longitudinal direction of the groove array provided on the first light guide plate.

In the backlight device 10 of this embodiment, in Embodiment 1, the first light guide plate 1 has groove arrays 1 _y on the main surface opposite to the first prism sheet 3 , and the optical components 1 _a having optical anisotropy are closely spaced. It is the same as the first embodiment except that it is attached to the groove surface 1 _z of the groove row 1 _y .

In more detail, on one main surface of the first light guide plate 1 according to this embodiment, the groove row 1 _y is continuously provided, and the longitudinal direction of the groove row 1 _y is aligned with the light from the first light source 2 of the first light guide plate 1 . The incident end face 1 _x of the first prism sheet 3 is substantially parallel to the ridge line direction of the triangular prism array of the first prism sheet 3 . The optical component 1 _a is formed by filling the groove row 1 _y with an optically anisotropic liquid crystal material, has optical anisotropy, and is closely attached to the groove surface 1 _z of the groove row 1 _y .

For example, the first light guide plate 1 related to this embodiment adopts acrylic resin (refractive index: 1.49), and the optical member 1 _a related to this embodiment has optical anisotropy, and adopts ultraviolet curable liquid crystal material (major axis direction The refractive index of 1.5, the refractive index of the minor axis direction is 1.7), and can be produced as follows. However, as described above, the refractive index of one of the liquid crystal materials forming the optical member 1 _a is substantially equal to the refractive index of the first light guide plate 1 .

First, by injection molding using the acrylic resin above, the first light guide plate 1 having the groove array 1 _y whose longitudinal direction is substantially parallel to the incident end face 1 _x of the light from the first light source 2 on one main surface is manufactured, and if necessary, An alignment film is formed or a rubbing treatment is performed on the surface of the groove array 1 _y .

Next, in order to fill the groove array 1 _y of the first light guide plate 1 , the above-mentioned ultraviolet curable liquid crystal material is applied and cured by irradiation with ultraviolet rays, whereby the optical member 1 having optical anisotropy is formed.

FIG. 20 is a schematic diagram showing the alignment state of liquid crystal molecules in the optical component 1 _a having optical anisotropy according to the present embodiment. As shown in FIG. 20 , the cross-sectional shape perpendicular to the longitudinal direction of the groove row 1 _y provided on the first light guide plate 1 is an equimembrane triangle shape with an apex angle γ of about 160 to 175 degrees and a wide apex angle. As shown in FIG. 20 , the optical component 1 _a according to the present embodiment fills grooves having a triangular cross section so that the long axis direction of the rod-shaped liquid crystal molecules 40 is aligned substantially perpendicular to the flat main surface of the first light guide plate 1 . And hardened to become a triangular prism, which has optical anisotropy with the direction perpendicular to the main surface of the first light guide plate 1 as the optical axis. Here, the refractive index of the liquid crystal molecules 40 in the minor axis direction is different from that of the first light guide plate 1 , and the refractive index of the major axis direction is substantially equal to that of the first light guide plate 1 .

In addition, in order to more stably form the vertical alignment of liquid crystal molecules as described above, it is more effective to use a polyimide or polyvinyl alcohol film with an alkyl chain as the alignment film 50 coated on the groove surface 1 _z of the groove array 1 _y . .

The transmissive display device using the backlight device 10 of this embodiment, as shown in FIG. Furthermore, polarizing plates 7d and 7e are provided so as to sandwich the glass substrates 7a and 7b.

Generally speaking, in a transmissive display device, the light emitted from the backlight device 10 selects only linearly polarized light components by the polarizer 7e of the transmissive display panel 7, and reaches the liquid crystal layer 7c after passing through the glass substrate 7b. In many cases, the polarizing plate absorbs the polarized light component corresponding to the absorption axis of the polarizing plate 7e among the light emitted from the backlight unit 10 due to dichroic absorption. That is, half of the light emitted from the backlight device 10 is uselessly absorbed, which is a cause of greatly reducing the light utilization efficiency of the liquid crystal display device.

Therefore, as shown in FIG. 20 , the backlight device 10 of the present embodiment utilizes the above-mentioned useless light by providing the optical member 1 _a having optical anisotropy on the groove row 1 _y of the first light guide plate 1 . The operation will be described below.

As shown in FIG. 19 , the light emitted from the first light source 2 has linearly polarized light including electric field components in the _y- length direction perpendicular to the groove row 1 of the first light guide plate 1 (that is, within the paper plane), that is, p waves 2 _p , _{The y-} length direction of the groove row 1 parallel to the first light guide plate 1 (that is, the plane perpendicular to the paper surface) contains the linearly polarized light of the electric field component, that is, the s-wave 2 _s , and is incident on the first light guide plate 1 from the end surface 1 _x .

Among the incident light, the p wave 2 _p performs Fresnel reflection on the interface between the first light guide plate 1 and the optical component 1 _a corresponding to the refractive index difference between the acrylic resin and the liquid crystal material of 0.2, and transmits it from the transmissive display panel 7 The light that exceeds the critical angle is radiated from the side surface, is bent toward the front by the first prism sheet 3, and then passes through the polarizing plate 7e of the transmissive display panel 7. At this time, the transmission axis of the polarizing plate 7e is set to pass the direction of the p-wave, and since there is no light loss here, the utilization efficiency of light is high.

On the other hand, among the light coming out from the light source 2 and incident on the first light guide plate 1 from the end face _1x , the s-wave 2 _s and the p-wave not reflected on the interface with the optical component _1a are transmitted by the optical component 1 The bottom surface of _a undergoes total reflection and propagates to the first light guide plate 1. On the way, due to the birefringence of the acrylic resin of the first light guide plate 1, the phase of the s wave 2 _s also changes accordingly to generate the p wave 2 _p component , and used for display in the same manner as above.

In addition, in this embodiment, as shown in FIG. 19 , a reflection plate 51 and a 1/4 wavelength plate 52 are attached to the end face of the first light guide plate 1 opposite to the first light source 2 .

Therefore, the light propagating through the first light guide plate 1 and reaching the end face opposite to the first light source 2 is reflected by the reflection plate 51 and enters the first light guide plate 1 again. At this time, the s-wave 2 _s with a high remaining ratio becomes the p-wave 2 _p by the 1/4 wavelength plate 52 . The p-wave _2p incident again on the first light guide plate 1 is reflected at the interface with the optical member _1a in the same manner as above, and is used for display in the same manner as above.

As described above, in the backlight device 10 of the present embodiment, most of the light emitted from the first light source 2 can be taken out from the first light guide plate 1 as p waves _2p , and the light emitted from the first light source 2 can be highly Efficiently used for display, brightness can be improved.

In addition, even if the first light guide plate 1 and the optical member 1 _a according to this embodiment are used, since no new stray light is generated, as shown in the first embodiment, the light from the first light source 2 has directionality and is transmitted from The first light guide plate 1 emits light. That is to say, the above-mentioned light from the first light source 2 enters the triangular-shaped prism row of the first prism sheet 3 as light a1 having directivity in a direction inclined with respect to the normal direction, and passes through the inclined plane of the triangular-shaped prism row It is reflected and emitted from the emission surface 30 of the first prism sheet 3 as light a2 having directivity in the normal line direction, thereby irradiating the front direction.

Next, the behavior of light b1 incident on the main surface of the first light guide plate 1 from the second light source 4 is considered. The light b1 from the second light source 4 has the linearly polarized light 4 _x passing through the polarizing plate 7 e and the absorbed linearly polarized light 4 _y , but no matter what kind of light, its electric field component is parallel to the flat main surface of the first light guide plate 1 . As for the direction parallel to the main surface of the first light guide plate 1, since there is no difference in refractive index at the interface between the first light guide plate 1 and the optical member _1a , these linearly polarized lights can travel without being refracted.

Therefore, groove arrays are provided on the second light guide plate 11 of the backlight device according to the fourth embodiment similarly to the first light guide plate 1 according to the present embodiment, and the optical member having optical anisotropy according to the present embodiment is made Closely attached to the groove surface of this groove row. In this way, the light b1 from the second light source 4 can be made into light having more linearly polarized light components passing through the polarizing plate 7e, and the utilization efficiency of the light b1 from the second light source 4 can be improved, so that the backlight device 10 The brightness is further improved.

Next, a case where the optical member 1 _a according to this embodiment is formed using disk-shaped discotic liquid crystal molecules instead of aligning rod-shaped liquid crystal molecules as shown in FIG. 20 will be described.

FIG. 21 is a schematic diagram showing an alignment state of liquid crystal molecules in an optical component 1 _a of another backlight device according to this embodiment. That is to say, using the first light guide plate 1 provided with the groove row 1 _y of the cross-sectional shape shown in FIG. The groove rows 1 _y are filled and hardened in a parallel orientation. Such alignment of liquid crystal molecules can be realized by appropriately selecting the alignment film 50 provided on the groove surface 1 _z of the groove row 1 _y of the first light guide plate.

Here, the refractive index of the acrylic resin in the first light guide plate 1 and the refractive index in the radial direction of the discotic liquid crystal molecules of the optical member 1 _a are set to be approximately equal, and the refractive index of the above-mentioned acrylic resin, The refractive index in the direction perpendicular to the radial direction of the cholesteric liquid crystal molecules 41 is set to a different value. Thereby, similar to the case of using the above-mentioned rod-shaped liquid crystal molecules 40, the p-wave can be reflected by the optical member _1a , and the p-wave can be efficiently emitted from the first light guide plate 1 and used for display, thereby improving luminance.

In this embodiment, as shown in FIG. 20 or FIG. 21 , the cross-section in the direction perpendicular to the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is a triangle whose hypotenuse is a straight line, and is closely attached to the groove row 1 The case where the optical member 1 _a of _{the y} groove surface 1 _z constitutes a triangular prism array has been described, but the shapes of the groove array 1 _y and the optical member 1 _a are not limited to this. That is to say, as shown in FIG. 22 , the cross-sectional shape in the direction perpendicular to the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is such that the hypotenuse is not a straight line as shown in FIG. 20 , but A triangular shape that curves slightly outwards or inwards from a straight line. In this case, if the maximum inclination angles α and β of the curves of the hypotenuses are 3° to 10° inclining from the main surface direction of the first light guide plate 1 , the same effect as that of the present embodiment can be easily obtained.

In addition, in this embodiment, the optical component 1 _a is arranged on the opposite side of the first prism sheet 3 of the first light guide plate 1 , but no matter whether it is arranged on the first prism sheet 3 side of the first light guide plate 1 or further On both sides of the first light guide plate 1, the same effects as those of the present embodiment can be obtained.

In addition, the present embodiment shows the case where one of the optical components 1 _a has optical anisotropy, but whether the first light guide plate 1 has optical anisotropy on one side or both are optically anisotropic materials, it does not matter. The same effects as those of the present embodiment can be obtained. Here, the materials constituting the first light guide plate 1 and the optical member 1 a are selected so that there are refractive index values such that the first light guide plate 1 and the optical member 1 _a are substantially equal to each other.

In addition, in this embodiment, since the ridge line direction of the triangular prism row of the first prism sheet 3 is parallel to the incident end face of the light from the first light source 2 of the first light guide plate 1, it is possible to 3 The emitted light is easily uniform within the surface of the first prism sheet 3 . Furthermore, since the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is parallel to the ridgeline direction of the triangular prism row of the first prism sheet 3 , rotation when polarized light passes through the first prism sheet 3 can be prevented. Furthermore, since the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is parallel to the incident end surface 1 _x of the light from the first light source 2 , brightness unevenness hardly occurs.

Embodiment 6

23 is an explanatory view showing a backlight device according to Embodiment 6 of the present invention, and a transmissive light path of a transmissive display device using the same, and a transmissive state of a transmissive panel. Section view of perpendicular planes.

The backlight device 10 of this embodiment is the same as that of the fifth embodiment except that the optical member 1 _a is obtained by orienting the rod-shaped liquid crystal molecules used in the fifth embodiment in a direction different from that of the fifth embodiment.

That is, in the anisotropic optical component 1 _a according to this embodiment, the long-axis direction of the rod-shaped liquid crystal molecules is in a direction parallel to the longitudinal direction of the groove row 1 _y of the first light guide plate 1 , that is, Oriented in a plane direction perpendicular to the paper plane.

The first light guide plate 1 according to this embodiment uses the same acrylic resin as the above-mentioned embodiment as the molding material, and for example, the side surface perpendicular to the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is provided in the inner cavity. The injection port (gate) for injecting the molten molding material is made by injection molding.

Next, in order to fill the groove row 1 _y of the first light guide plate 1, the same ultraviolet-curable liquid crystal material as used in Embodiment 5 is applied, cured by irradiation with ultraviolet rays, and the long-axis direction of the rod-shaped liquid crystal molecules is aligned with that of the first light-guiding plate 1. The longitudinal direction of the groove array 1 _y of a light guide plate 1 is oriented in parallel to form an optical component 1 _a having optical anisotropy.

On the other hand, after suitably manufacturing the first light guide plate 1 in which the groove row 1 _y has been formed, the groove surface 1 _z is rubbed with an abrasive, and then, by selecting the abrasive, an ultraviolet-curable UV-curable coating is applied in the same manner as above. The liquid crystal material is cured to align the rod-shaped liquid crystal molecules 40 with their long axes parallel to the longitudinal direction of the groove array 1 _y of the first light guide plate 1 to form an optical component 1 _a with optical anisotropy.

In addition, the optical axis of the optical component ₁ a obtained as above becomes parallel to the longitudinal direction of the groove array 1 _y .

As shown in FIG. 23 , the s-wave 2 _s of the light coming out of the first light source 2 and entering the first light guide plate 1 from the end surface 1 _z is at the interface between the first light guide plate 1 and the optical component 1 _a . Fresnel reflection is carried out corresponding to the refractive index difference of 0.2, and the light exceeding the critical angle is radiated from the side of the transmissive display panel 7 , and passes through the polarizer 7 e of the transmissive display panel 7 after being bent toward the front direction a2 by the first prism sheet 3 . At this time, the transmission axis of the polarizing plate 7e is set to pass through the direction of the s-wave, and since there is no light loss here, the utilization efficiency of light is high. In addition, since the Fresnel reflectance of the s-wave is higher than that of the p-wave, light can be easily extracted from the light guide plate, and there is an effect that the overall light utilization efficiency can be improved.

As described above, in the backlight device 10 of this embodiment, most of the light emitted from the first light source 2 can be extracted from the first light guide plate 1 as s-waves 2 _s , and the light from the first light source 2 can be highly Efficiently used for display, brightness can be improved.

In addition, even if the first light guide plate 1 and the optical member 1 _a according to this embodiment are used, since no new stray light is generated, as shown in the first embodiment, the light from the first light source 2 has directionality and is transmitted from The first light guide plate 1 emits light. That is to say, the above-mentioned light from the first light source 2 enters the triangular-shaped prism row of the first prism sheet 3 as light a1 having directivity in a direction inclined with respect to the normal direction, and passes through the inclined plane of the triangular-shaped prism row It is reflected and emitted from the emission surface 30 of the first prism sheet 3 as light a2 having directivity in the normal direction, thereby irradiating the front direction.

Next, the behavior of light b1 incident on the main surface of the first light guide plate 1 from the second light source 4 is considered. The light b1 from the second light source 4 has the linearly polarized light 4 _x passing through the polarizing plate 7e and the absorbed linearly polarized light 4 _y , the electric field component is perpendicular to the linearly polarized light of the length direction of the groove column 1 _y of the first light guide plate 1 , because there is no refractive index difference at the interface of the first light guide plate 1 and the optical component 1 _y . On the other hand, the linearly polarized light whose electric field component is parallel to the longitudinal direction of the groove row 1 _y of the first light guide plate 1 is refracted at the interface between the first light guide plate 1 and the optical component 1 _y due to the difference in refractive index. For this reason, it is desirable that the optical component 1 _a has an obtuse angle with an apex angle of 170 to 175 degrees.

Also, instead of the optical member 1 _a according to the present embodiment, the optical member 1 a is formed by aligning the radial direction of the disk-shaped liquid crystal molecules 41 substantially parallel to the flat main surface of the first light guide plate 1 _. , the same effects as those of the present embodiment can also be obtained. That is to say, the s-wave 2 _s among the light coming out from the first light source 2 and entering the first light guide plate 1 from the end surface _1x can be efficiently extracted from the first light guide plate 1, and the same high Efficiently used for display. However, in this case, the refractive index of the acrylic resin of the first light guide plate 1 and the refractive index of the cholesteric liquid crystal in the optical member 1 _a in the radial direction are set to different values, and the sum of the refractive indices of the acrylic resin and The refractive indices in the direction perpendicular to the radial direction of the cholesteric liquid crystal molecules are set to approximately equal values.

Embodiment 7

24 is a configuration diagram showing the structure of a transmissive display device according to Embodiment 7 of the present invention, using the transmissive display panel 7 and the backlight device 10 according to Embodiment 1. FIG. On the transmissive display panel 7, an image signal is displayed by an image driving part. In addition, the directional light from the second light source in the normal direction is bent in the left and right directions by the first prism sheet 3, and illuminates the front direction and the left and right directions of the transmissive display panel 7 respectively.

In the backlight device 10 used in this embodiment, as shown in FIG. The output can transmit the image displayed on the transmissive display panel 7 to the observer in the front direction.

On the other hand, as shown in FIG. 5( b ), the light from the second light source 4 is bent in the left and right directions of -30 degrees or less and 30 degrees or more with respect to the normal direction, and is emitted toward the observer. The image displayed on the transmissive display panel 7 is conveyed to observers in the left and right directions deviated from the front direction.

In addition, in this embodiment, the front direction and the left-right direction are adjusted independently by the light source control unit 6, whereby uniform light can be irradiated with a wide viewing angle.

Embodiment 8

25 is a configuration diagram of a transmissive display device according to Embodiment 8 of the present invention, in which a synchronous drive unit is added to the transmissive display devices according to Embodiments 5 to 7. FIG.

On the transmissive display panel 7, two different image signals are alternately displayed by the image driving part, and are synchronized with the above-mentioned image signals by the synchronous driving part 16, and alternately switch the first direction of the front direction of the irradiating transmissive display panel 7. A light source and a second light source illuminating the left and right directions of the transmissive display panel 7 . Specifically, using the synchronous driving unit 16, the first light source 2 is turned on when the image for the front direction is displayed, and the second light source 4 is turned on when the image for the left and right direction is displayed, and one light source point Turning off the other light source when it is on is switched by the light source control unit 6 .

26 is an explanatory diagram of a display image using a transmissive display device according to Embodiment 8 of the present invention. FIG. (b) is the angular distribution of the image guided to the viewer in the left and right directions and the irradiated light from the backlight device.

With the backlight device 10 related to this embodiment, as shown in FIG. 4( b ), light with an angular distribution that is converged at -20 degrees to 20 degrees relative to the normal direction, and as shown in FIG. 5( b ) The transmissive display panel 7 is irradiated with light having an angle distribution bent in the left-right direction of -30 degrees or less and 30 degrees or more with respect to the normal direction. On the other hand, two different images, an A image for the front direction and a B image for the left and right directions, are alternately displayed on the liquid crystal panel 20 by the image driving means. Therefore, through the synchronous drive unit 16, the above-mentioned image signals and the switching of the first light source 2 and the second light source 4 by the light source control unit 6 are synchronized. If this switching is repeated at a frequency of 60 Hz or more, the As shown in 26 , the A image is recognized brightly by the observer in the front direction, and the B image is recognized as a continuous bright image by the observer in the left and right directions.

As described above, it is possible to display an image that is easily seen by the observer who is facing it, and to display a different image to the surrounding people who are viewing from the left and right oblique directions, and to hide the image viewed by the frontal observer from the surrounding people. Effect.

In addition, in the backlight device 10, since the viewing angle adjustment film 5 is provided on the surface side of the first light guide plate opposite to the prism side, it absorbs the light leaked downward from the first light guide plate 3 and prevents it from becoming Effect of stray light. Since the stray light is reduced, the light leaking to the left and right directions when the upper first light source 4 is turned on is reduced, so the risk of the front image being peeped from the left and right directions is reduced.

Claims (15)

1. A backlight device, characterized in that: The first prism sheet has triangular prism columns on one surface; The first light source will have directional light on the direction inclined with respect to the normal direction of the exit surface of the side opposite to the above-mentioned triangular-shaped prism row of the first prism sheet, and is incident on the triangular shape of the above-mentioned first prism sheet. prism columns; and The second light source injects light having directivity in a direction normal to an emission surface of the first prism sheet to the triangular prism array of the first prism sheet. 2. According to the backlight device recorded in claim 1, it is characterized in that having: The first light guide plate is arranged on the face side of the triangular prism row of the first prism sheet, Wherein, the first light source is disposed on the end face side of the first light guide plate, and the second light source is disposed on the opposite side of the first light guide plate to the first prism sheet. 3. According to the backlight device recorded in claim 1, it is characterized in that: Light incident from the second light source to the triangular prism array of the first prism sheet has an angular distribution of 60° to 80° around the normal direction of the output surface of the first prism sheet. 4. According to the backlight device recorded in claim 3, it is characterized in that: The vertex angle of the prisms of the triangular prism row is 60-65 degrees. 5. According to the backlight device recorded in claim 2, it is characterized in that: The second light source is provided through the viewing angle adjustment film. 6. According to the backlight device recorded in claim 2, it is characterized in that having: The second prism sheet is arranged on the opposite side of the first light guide plate to the first prism sheet; and The second light guide plate is arranged on the opposite side of the second prism sheet to the first light guide plate, and The second light source is provided on the end surface side of the second light guide plate. 7. According to the backlight device recorded in claim 2, it is characterized in that: The first light guide plate has, on at least one main surface, groove rows continuously arranged in a longitudinal direction substantially parallel to the ridgeline direction of the triangular prism rows of the first prism sheet, And it is equipped with an optical component that is closely attached to the groove surface of the groove row and has optical anisotropy. 8. According to the backlight device recorded in claim 7, it is characterized in that: The refractive index of one of the optical members is substantially equal to the refractive index of the first light guide plate. 9. According to the backlight device recorded in claim 7, it is characterized in that: The optical member is formed by orienting rod-shaped liquid crystal molecules such that the long-axis direction of the liquid crystal molecules is substantially perpendicular to the main surface of the first light guide plate. 10. The backlight device according to claim 7, characterized in that: The optical member is formed by aligning disk-shaped liquid crystal molecules so that the radial direction of the liquid crystal molecules is substantially parallel to the main surface of the first light guide plate. 11. The backlight device according to claim 7, characterized in that: The optical member is formed by orienting rod-shaped liquid crystal molecules such that the long-axis direction of the liquid crystal molecules is substantially parallel to the longitudinal direction of the groove array of the first light guide plate. 12. The backlight device according to claim 6, characterized in that: The second light guide plate has, on at least one main surface, groove rows continuously arranged in a longitudinal direction approximately parallel to the ridgeline direction of the triangular prism rows of the second prism sheet, And it is equipped with an optical component that is closely attached to the groove surface of the groove row and has optical anisotropy. 13. The backlight device according to claim 1, characterized in that: A light source control unit that independently controls the operations of the first and second light sources is provided. 14. A transmissive display device comprising a transmissive display panel and the backlight device according to claim 1. 15. A transmissive display device, comprising: Transmissive display panel; An image driving unit that alternately displays two different image signals on a transmissive display panel; The backlight device described in claim 13; A synchronous drive unit that synchronizes the flickering of the first and second light sources by the light source control unit of the backlight device with the above-mentioned respective image signals, and alternately switches them.

Images