JP2010160360A - Light distribution control sheet, light distribution control panel using same, display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve light distribution control for obtaining relatively high front surface luminance and reducing the ejection to an unnecessary angular field of view. <P>SOLUTION: This light distribution control panel 10 includes one or more strip-like projections 12 on a sheet-like substrate 11 having translucency. Projections 14 having a triangular end surface have a first light distribution control surface 12 where angle α with respect to a substrate surface is between 5° and 40° and a second light distribution control surface 13 where angle β with respect to the substrate surface is between 60° and 90°. A light control member 15 including a light shielding film such as a black film for blocking the transmission of light and an antireflective film such as a silicon oxide film is disposed on the second light distribution control surface 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light distribution control sheet, specifically to a light distribution control sheet for efficiently emitting light from a light source in a specific direction, a light distribution control panel using the sheet, and a display device.

  In recent years, a moving body represented by an automobile is often equipped with a display device that presents various information to a driver, for example, a car navigation system. Such display devices are typically placed on a dashboard in front of the driver's seat. At this time, depending on the installation angle of the windshield of the automobile, an image displayed on the display device may be reflected on the windshield, and the reflected image is clearly visible at night. As a result, it may become an obstacle to driving.

  Under such circumstances, for example, Japanese Patent Application Laid-Open No. 2001-305312 (Patent Document 1) discloses a louver film having first and second main surfaces and a polarizing film on the first main surface of the louver film. A liquid crystal display panel is disclosed in which an optical element including a laminated and fixed polarizing film is disposed between a backlight and a liquid crystal panel. In this liquid crystal display panel, the louver in the optical element exerts the effect of controlling the traveling method of the light transmitted through the louver film within a predetermined emission angle range, thereby eliminating the need for light transmitted through the liquid crystal panel in the lateral direction. Injection is suppressed. And the brightness | luminance of liquid crystal panel transmitted light is improved by presence of a polarizing film. Further, in this display panel, the emission angle range of the liquid crystal panel transmitted light can be controlled by changing the angle of the louver in the louver film with respect to the light from the backlight.

  Japanese Unexamined Patent Publication No. 2000-193809 (Patent Document 2) discloses a plate-like or sheet-like light distribution control sheet provided with a first light control means for light distribution control with a fine shape on one surface of a light source. A light distribution control sheet is disclosed in which second light control means having a fine shape is further provided on at least one surface of the light control means. In this light distribution control sheet, the prism or diffraction grating, which is the first light control means, refracts light incident from the outside of the sheet to control the emission direction of the sheet transmitted light. Examples of the second light control means include a minute prism, a minute conical protrusion, and a light diffusion surface. And this 2nd light control means distributes light in the direction which the 1st light control means wants to control in combination with the 1st light control means, and improves the light distribution nature of sheet transmission light. Yes.

JP 2001-30531 A JP 2000-193809 A

  Incidentally, FIG. 13 is a graph showing the luminance on the display surface of a liquid crystal display device using a louver film. This figure is a graph showing an example of an effect using a louver film. As shown by the broken line in the figure, when the louver film is not used, the light transmitted through the liquid crystal panel spreads from the front to the left and right directions in a substantially left-right symmetrical manner at a wide emission angle, but when the louver film is used, As indicated by the solid line in the figure, the light transmitted through the liquid crystal panel spreads only at a narrow emission angle, and the light distribution is improved. The emission angle, that is, the viewing angle at which the light reaches depends on the louver arrangement interval, the louver angle, and the louver thickness (length in the optical axis direction).

  However, in the liquid crystal display panel described in Patent Document 1, since the louver film blocks light from the backlight, not only the front luminance of the display device decreases, but also the light use efficiency is remarkably low. Insufficient brightness. For this reason, there is a problem that the luminance of the backlight has to be increased, and means for preventing an increase in power consumption and a temperature rise in the liquid crystal display panel are required.

  On the other hand, in the light distribution control sheet described in Patent Document 2, the second light control unit performs emission control of light incident on the second light control unit in a direction controlled by the first light control unit. Therefore, the light use efficiency is increased and the front brightness can be maintained high. The peak of the luminance distribution viewed from the front of the sheet moves to a position shifted from the front to the left or right. That is, the peak of the luminance distribution is shifted in the direction to be controlled by the first light control means.

  However, in this light distribution control sheet, since light passes in a direction different from the direction to be controlled, light is also emitted at a viewing angle that is not originally required. Therefore, even if this light distribution control sheet is used for a display panel, it is expected that upward emission cannot be prevented and reflection on the windshield of an automobile cannot be sufficiently prevented.

  The present invention has been made in view of the background art described above, and an object of the present invention is to realize light distribution control that obtains a relatively high front luminance and reduces emission to an unnecessary viewing angle.

  The light distribution control sheet of the present invention is a light distribution control sheet provided with one or a plurality of strip-shaped convex portions on a light-transmitting sheet-like base material, and the convex portions are formed on the surface of the base material. A light distribution control surface having an acute angle or a right angle, and having at least two light distribution control surfaces different from each other, and having a large angle with the base material surface of the two light distribution control surfaces. The light control member is provided in at least a part of the area.

  According to the present invention, it has a strip-like convex part having two light distribution control surfaces with different angles formed with the substrate surface, and the angle formed with the substrate surface is large among the two light distribution control surfaces. Since a light control member is provided in at least a partial area of the light distribution control surface, the light distribution property to either the left or right field of view is improved while maintaining high front luminance, and the other field of view, that is, an unnecessary field angle can be obtained. Injection is almost suppressed.

It is a disassembled perspective view of the light distribution control panel which is one Embodiment of this invention. It is the end elevation which partially fractured the light distribution control sheet which is used for the same light distribution control panel. It is the schematic diagram which illustrated the relationship between the viewing angle in the front of a light distribution control panel same as the above, and a brightness | luminance. It is the end elevation which fractured | ruptured partially the light distribution control sheet which is other embodiment of this invention. It is a figure which shows the relationship between the viewing angle and the brightness | luminance at the time of simulating the light distribution control panel of this invention, Comprising: The case where the angle (alpha) which a 1st light distribution control surface and a base-material surface make is 30 degree | times is shown. It is a figure which shows the relationship between the viewing angle and the brightness | luminance at the time of simulating the light distribution control panel of this invention, Comprising: The case where the angle (alpha) which a 1st light distribution control surface and a base-material surface make is 25 degree | times is shown. It is a figure which shows the relationship between the viewing angle and the brightness | luminance at the time of simulating the light distribution control panel of this invention, Comprising: The case where the angle (alpha) which a 1st light distribution control surface and a base-material surface make is 20 degree | times is shown. It is a figure which shows the relationship between a viewing angle and the brightness | luminance at the time of simulating the light distribution control panel of this invention, Comprising: The case where the angle (alpha) which a 1st light distribution control surface and a base-material surface make is 15 degree | times is shown. It is a figure which shows the relationship between the viewing angle at the time of using the light distribution control panel of this invention, and the light distribution control panel which is not provided with the light control member which is a reference example, and a brightness | luminance. It is explanatory drawing which shows an example of the mobile body provided with the display apparatus for mobile body mounting of this invention. It is the end elevation which fractured | ruptured a part of light distribution control sheet | seat which is another embodiment of this invention. (A) and (b) are the end views to which the convex part of the light distribution control sheet which is further another embodiment of this invention was expanded, respectively. It is a figure which shows the relationship between the viewing angle and the brightness | luminance in the liquid crystal display panel using the louver film which is a prior art example.

  Hereinafter, the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a light distribution control panel according to an embodiment of the present invention, and FIG. 2 is an end view in which the light distribution control panel is partially broken. However, the embodiment shown below is an exemplification, and the present invention is not limited to the following embodiment, and all the modifications included in the scope of the claims and equivalents thereof are included in the present invention. It is intended to be included.

  The light distribution control panel 1 shown in FIG. 1 is a liquid crystal display panel. The light distribution control panel 1 distributes light from a backlight 30 that is a light source, a liquid crystal panel 20 that displays an image, and the backlight 30. A light distribution control sheet 10 that is controlled and emitted toward the liquid crystal panel 20 is provided.

  The light distribution control sheet 10 has a strip-like convex portion 12 on one surface of a translucent plate-like or sheet-like base material 11 and is called a so-called prism sheet or prism array. It is. In the light distribution control panel 1 shown in FIG. 1, the light distribution control sheet 10 is disposed between the backlight 30 and the liquid crystal panel 20 with the convex portion 12 facing the backlight 30 side. However, in the present invention, the light distribution control sheet 10 may be arranged on the display surface of the liquid crystal panel 20 with the convex portion 12 facing the liquid crystal panel 20 side. The configurations of the backlight 30 and the liquid crystal panel 20 are not particularly limited, and various known backlights and liquid crystal panels used in conventional liquid crystal display panels are exemplified.

  In the present invention, the strip-like convex portion 12 is a convex portion 12 having a length extending linearly, and at least one, preferably a large number of convex portions 12 are arranged in parallel. Means that. As shown in FIG. 1, the light distribution control panel 1 is preferably provided with a convex portion 12 having the same width as the sheet width (corresponding to the depth of the sheet in the figure). The length of the convex portion 12 is not necessarily the same length as the sheet width, and is appropriately designed according to the purpose of use, for example, the structure of the backlight. Further, the light distribution control sheet 10 may have a region where the base material 11 is exposed at the peripheral edge of the base material 11. As shown in the figure, it is preferable to arrange the convex portion 12 and the convex portion 12 without any gap, but there is no problem even if a gap is provided between the convex portion 12 and the convex portion 12 and arranged at a constant interval. .

  In this light distribution control sheet 10, a base material 11 and a convex portion 12 are integrally formed from a light-transmitting material such as glass, polycarbonate resin, or polyimide resin. In particular, in order to cope with the improvement in resolution of the liquid crystal panel 20, the fine convex portion 12 is required. For this purpose, a resin material that can be transferred using a mold in which a fine transfer pattern is formed. Are preferably used.

  The light distribution control sheet 10 shown in FIG. 1 has a triangular side end face (cross section) as shown in FIG. 2, and two light distribution control surfaces on the side surface, that is, a first light distribution control surface. 13 and a second light distribution control surface 14. The angle α formed by the first light distribution control surface 13 and the surface of the base material 11 (hereinafter referred to as “base material surface”) is different from the angle β formed by the second light distribution control surface 14 and the base material surface. One is a right angle or an acute angle and the other is an acute angle. For example, in the example shown in FIG. 2, the angle α formed by the first light distribution control surface 13 and the substrate surface is smaller than the angle β formed by the second light distribution control surface 14 and the substrate surface.

  In the light distribution control sheet 10 of the present invention, the light distribution control surface having a larger angle with the substrate surface, that is, the second light distribution control surface 14 in the illustrated example, includes the light control member 15. The light control member 15 suppresses transmission and reflection of light from the second light distribution control surface 14 and reduces luminance at an unnecessary viewing angle. The light control member 15 is not particularly limited as long as it is a film that suppresses transmission and reflection. For example, the light control member 15 is formed of a black film that absorbs light in the visible region or an antireflection film such as a silicon oxide film. The former can be formed by, for example, vapor deposition of graphite, and the latter can be formed by, for example, sputtering silicon oxide. It is also possible to form a black film in a necessary area of the mold on which the fine transfer pattern is formed and transfer it. It is not sufficient for the light control member 15 to reduce the luminance at an unnecessary viewing angle, and it is desired to suppress the luminance to almost zero. Accordingly, the light diffusion surface described in Patent Document 2 is insufficient, and an antireflection film such as a black film or a silicon oxide film that absorbs the light is desirable. Of course, as long as the luminance at an unnecessary viewing angle can be made almost zero, the configuration is not limited.

  The light control member 15 is preferably formed on the entire second light distribution control surface 14, but if the luminance at an unnecessary viewing angle can be reduced, preferably almost zero, it may be partially formed. It can be formed.

  FIG. 3 is a schematic view illustrating the relationship between the viewing angle and the luminance in the front of the light distribution control panel 1. 3 indicates the case where the light distribution control sheet 10 of the present invention in which the light control member 15 is provided on the entire surface of the second light distribution control surface 14 is used, and the broken line c indicates the first light distribution control surface 13. When the light distribution control sheet 10 having the same angle α formed by the substrate surface and the angle β formed by the second light distribution control surface 14 and the substrate surface is used (when the light control member 15 is not provided), The angle α formed by the first light distribution control surface 13 and the base material surface is different from the angle β formed by the second light distribution control surface 14 and the base material surface, but the second light distribution control surface 14 is controlled by light. The case where the light distribution control sheet 10 which does not have the member 15 is used is shown. The vertical axis in FIG. 3 indicates the relative luminance, and the horizontal axis indicates the viewing angle from the front. Light is emitted from the first light distribution control surface 13, and the viewing angle is in the negative direction (indicated by the arrow in FIG. 2). It shows that light is emitted in the emission direction.

  As shown by the broken line C in FIG. 3, when the angle α and the angle β are equal, that is, in the light distribution control sheet 10 in which the first light distribution control surface 13 and the second light distribution control surface 14 are symmetric. , A luminance distribution that is symmetric when viewed from the front is obtained, but by changing the angle α and the angle β, as shown by the dashed line a in FIG. The luminance distribution shifts to the viewing angle side. However, in this case, as shown in the drawing, the luminance at the positive viewing angle, that is, the unnecessary viewing angle side is relatively high, and reflection on the windshield of the automobile cannot be sufficiently prevented.

  However, when the second light distribution control surface 14 is provided with the light control member 15 made of a light shielding film or an antireflection film as in the present invention, the spread of light is cut as in the case of using a louver film ( Although the effect of shaping up is not produced, the light tailing to the other visual field side is cut while the central axis of the luminance distribution is shifted to the one visual field side. That is, when the light distribution control sheet 10 having the structure shown in FIG. 2 is used, the luminance distribution shifts to the negative viewing angle as shown by the solid line a in FIG. The luminance can be reduced from a small viewing angle, and the luminance when the viewing angle is, for example, 25 degrees to 30 degrees or more can be made almost zero. As a result, when used in a liquid crystal display panel in a car navigation system, unnecessary upward emission can be eliminated and reflection on the windshield is prevented.

  The angle α formed between the first light distribution control surface 13 and the substrate surface and the angle β formed between the second light distribution control surface 14 and the substrate surface are appropriately set according to the required light distribution characteristics. By changing the angle α and the angle β, it is possible to adjust the viewing angle as a dark region, that is, the angle at which the luminance becomes almost zero. The luminance at the viewing angle at which the luminance decreases tends to depend on the formation accuracy of the light control member 15, that is, the light transmission degree (light shielding degree) and the light reflection degree of the light control member 15. If formed accurately, the luminance at an unnecessary viewing angle approaches nearly zero, and the luminance does not become zero when the light shielding property and light reflectivity of the light control member 15 are lowered. As can be understood from the following simulation, in order to reduce the luminance to zero on the unnecessary viewing angle side, the smaller angle, that is, the angle α between the first light distribution control surface 13 and the base material surface is 5 degrees. It is preferable that the larger angle of 40 degrees or less, that is, the angle β between the second light distribution control surface 14 and the substrate surface is set to 60 degrees or more and less than 90 degrees. By adjusting within this range, the luminance in the range (one side) larger than the desired viewing angle can be made almost zero.

  Of course, in the light distribution control sheet 10 of the present invention, not only the convex portion 12 is arranged on the light source side as shown in FIG. 2, but the convex portion 12 is arranged on the opposite side to the light source side as shown in FIG. It doesn't matter. Even in this case, the light control member 15 is formed on the second light distribution control surface 14 having a large angle β with the base material surface.

  5 to 8 are diagrams showing the relationship between the viewing angle and the luminance when the light distribution control panel 1 of the present invention is simulated, and the angle α formed between the first light distribution control surface 13 and the base material surface and the second angle. In this case, the angle β formed by the light distribution control surface 14 and the substrate surface is changed. In each figure, when the angle α formed by the first light distribution control surface 13 and the substrate surface is 30 degrees, 25 degrees, 20 degrees, and 15 degrees, the second light distribution control surface 14 and the substrate surface are In this example, the angle β formed is changed to 70 degrees, 75 degrees, 80 degrees, 85 degrees, and 90 degrees. In each figure, a line indicated by BL indicates a backlight light source. For reference, in FIG. 9, when the light distribution control sheet 10 of the present invention is used (the product of the present invention: α = 25 degrees, β = 85 degrees), a light distribution control sheet without the light control member 15 is used. Comparison is shown with the case of using (Reference Example 1: α = 25 degrees, β = 85 degrees) and the case of using a light distribution control sheet having the same angle α and angle β (Reference Example 2: 160 ° prism). . The light distribution control sheet 10 has the configuration shown in FIG. 2, and the refractive index of the material is 1.53, the thickness of the substrate 11 is 200 μm, the width (pitch) of the convex portions 12 is 100 μm, and the second light distribution control surface. Assuming that the light transmittance at 14 is zero, a simulation was performed in a state where light was applied from the convex portion 12 side.

  According to this simulation, in the light distribution control sheet 10 of the present invention, it depends on the angle α formed between the first light distribution control surface 13 and the substrate surface and the angle β formed between the second light distribution control surface 14 and the substrate surface. It is understood that the luminance is almost zero in the range where the emission angle is +25 degrees or more.

  FIG. 10 is a diagram showing an example in which the light distribution control panel 1 of the present invention is used for a moving body such as an automobile. For example, the light distribution control panel 1 of the present invention is used in a display device for mounting on a moving body, for example, a display unit 2 of a car navigation system, a display unit 3 such as a speedometer, or the like. As described above, the light distribution control sheet 10 of the present invention shifts the peak of the luminance distribution from the almost front of the light distribution control panel 1 to the required viewing angle side, and the luminance on the viewing angle side that is unnecessary. Can be brought close to zero. Therefore, the image displayed on the windshield of the display unit 2 such as the display unit 2 of the car navigation system, the speedometer, or the so-called tachometer for displaying the rotation speed of the engine is prevented, thereby contributing to safe driving.

  In the above-described embodiment, the convex portion 12 has a triangular shape on the end surface. However, the angle β between the first light distribution control surface 13 and the base material 11 is the angle α with the base material 11. If the second light distribution control surface 14 is formed, for example, as shown in FIG. 11, the convex portion 12 having a substantially trapezoidal end surface having the third light distribution control surface 16 on the light emission side is formed. It doesn't matter. Even in this case, if the light control member 15 is formed on the second light distribution control surface 14 having a large angle with the base material 11, the luminance at an unnecessary viewing angle can be made substantially zero. Further, in this case, it is preferable that the third light distribution control surface 16 is directed in the light emission direction so as to prevent emission to an unnecessary viewing angle.

  The first light distribution control surface 13 and the second light distribution control surface 14 are generally formed in a planar shape as shown in FIGS. 1 and 2, but are not necessarily formed in a planar shape. As shown in FIG. 12 (a), each light distribution control surface 13, 14 may be formed so as to bulge in a convex shape or may be formed in a concave shape as shown in FIG. 12 (b). There is no problem. In addition, although not shown, it is also possible to expand one of the light distribution control surfaces and dent the other light distribution control surface. Note that the angle α or β formed with the base material 11 in these cases is the tangent (tangential plane) at each center point 18 of the first light distribution control surface 13 or the second light distribution control surface 14 as shown in the figure. It shall mean the angle formed by the substrate surface.

  In the above embodiment, the light distribution control panel 1 provided with the backlight 30 as the image display panel has been described. However, in the present invention, a self-luminous image display panel (not shown) can also be used. The self-luminous image display panel is different from the liquid crystal display panel 20 in which an image is displayed on the liquid crystal display panel 20 by the backlight 30 described above, and the backlight 30 is unnecessary, and an image is obtained using a light emitter provided in the image display panel as a light source. Can be displayed. The light distribution control sheet 10 of the present invention is also applicable to such a self-luminous image display panel, and is an organic EL panel using an organic material (organic electroluminescence) as an illuminant or an inorganic material (inorganic electroluminescence). It can be applied to any inorganic EL panel using The light distribution control sheet 10 is disposed on the image display surface side of the self-luminous image display panel. At this time, the convex portion 12 can be arranged on the image display surface side or can be arranged on the light emitting side. Thus, in the present invention, the image display panel is used in a broad sense including various image display panels such as a liquid crystal panel using a backlight light source, a self-luminous display panel such as an organic EL panel and an inorganic EL panel, By combining the image display panel and the light distribution control sheet of the present invention, the light distribution can be further enhanced.

DESCRIPTION OF SYMBOLS 1 Light distribution control panel 2 Display part 3 of a car navigation system 3 Display parts, such as a speedometer 10 Light distribution control panel 11 Base material 12 Convex part 13 1st light distribution control surface 14 2nd light distribution control surface 15 Light control Member 20 Liquid crystal panel 30 Backlight

Claims (10)

A light distribution control sheet comprising one or a plurality of strip-shaped convex portions on a sheet-like substrate having translucency,
The convex part has at least two light distribution control surfaces whose angles to the substrate surface are acute angles or right angles, and whose angles are different from each other,
The light distribution control sheet | seat in which the light control member was provided in the at least one partial area | region of the light distribution control surface with a large angle made with the said base material surface among two said light distribution control surfaces.   The light distribution control sheet according to claim 1, wherein a light control member is provided on the entire surface of the light distribution control surface.   The light distribution control sheet according to claim 1, wherein the light control member is a black film.   The light distribution control sheet according to claim 1, wherein the light control member is an antireflection film.   The light distribution control sheet according to claim 1, wherein the convex portion has a triangular cross section.   The angle formed by one light distribution control surface and the substrate surface is 5 degrees or more and 40 degrees or less, and the angle formed by the other light distribution control surface and the substrate surface is 60 degrees or more and 90 degrees or less. The light distribution control sheet according to claim 1. The light distribution control sheet according to any one of claims 1 to 6,
Light distribution control panel with image display panel.   The light distribution control panel according to claim 7, wherein the image display panel is a display panel including a light source and a liquid crystal display panel.   The light distribution control panel according to claim 7, wherein the image display panel is a self-luminous image display panel.   A moving body-mounted display device comprising the light distribution control panel according to any one of claims 7 to 9.

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