Patent Application
20110128470
The present invention relates to a light distribution control panel, a display device for mounting on a mobile unit, a light distribution control sheet, an optical component, a lighting device, and a display device. More particularly, the present invention relates to a light distribution control panel that can control light distribution, and a display device for mounting on a mobile unit. Specifically, the present invention relates to a light distribution control sheet for efficiently emitting light from a light source in a particular direction, as well as a light distribution control panel and a display device in which the sheet is used. In addition, the present invention relates to an optical component that can be suitably used for viewing angle control. Furthermore, the present invention relates to a lighting device and a display device in which such an optical component is used.
A light distribution control panel that controls light distribution direction of light has conventionally been known (see, for example, Japanese Patent Laying-Open No. 2000-193809 (hereinafter referred to as Patent Document 1)). Patent Document 1 discloses a sheet-like light distribution control panel made of a translucent material for the purpose of efficiently directing light toward a particular direction without impairing softening of light, wherein light control means (e.g., a prism that is a linear projection having a triangular cross-sectional shape) for light distribution control with a minute shape is formed on one surface on a light source side, and second light control means (e.g., a minute prism, a diffraction grating or a diffusing surface) with a further minute shape is formed on one surface of the prism. In Patent Document 1, the use of the light distribution control panel mainly in outdoor lighting equipment is assumed.
In addition, in recent years, a display device for presenting various information to a driver and the like, for example a car navigation system and the like, has been mounted in many cases on a mobile unit typified by a vehicle. Such a display device is generally positioned on a dashboard in front of the driver's seat. In some cases, an image displayed on the display device is reflected on a windshield of the vehicle, depending on the angle at which the windshield is placed. During nighttime, the reflected image is visually identified clearly, which may result in an obstacle to driving.
Under these circumstances, Japanese Patent Laying-Open No. 2001-305312 (hereinafter referred to as Patent Document 2), for example, discloses a liquid crystal display panel, wherein an optical element is positioned between a backlight and a liquid crystal panel, and the optical element includes a louver film having first and second main surfaces and a polarizing film stacked on and fixed to the first main surface of this louver film. In this liquid crystal display panel, a louver in the optical element produces the effect of controlling, to a prescribed emission angle range, a traveling direction of light passing through the louver film, and thus, unnecessary emission of light passing through the liquid crystal panel toward the direction of right and left side surfaces is suppressed. The presence of the polarizing film enhances the luminance of the light passing through the liquid crystal panel. In addition, in this display panel, the emission angle range of the light passing through the liquid crystal panel can be controlled by changing the angle of the louver in the louver film with respect to light from the backlight.
Patent Document 1 also discloses a plate-like or sheet-like light distribution control sheet, wherein first light control means for light distribution control with a minute shape is provided on one surface on a light source side, and second light control means with a further minute shape is provided on at least one surface of the light control means, as described above. In this light distribution control sheet, a prism or a diffraction grating serving as the first light control means refracts light incident from outside the sheet, thereby controlling the emission direction of light passing through the sheet. In addition, a very small prism, a very small cone-shaped projection or a light diffusing surface is described as an example of the second light control means. Together with the first light control means, this second light control means distributes light toward a direction in which the first light control means wants to control light, and enhances the light distribution characteristics of the light passing through the sheet.
An optical component that employs the viewing angle control technique has also been used for a display such as a liquid crystal display in order to prevent a peep at a display of a mobile phone or a display of a personal computer, as in the case of preventing reflection on a front panel of the car navigation as described above. In such an optical component, light from the display is emitted only to a certain range of the viewing angle.
Such an optical component includes a louver disclosed in Non-Patent Document 1. In this louver, a plurality of light blocking plates are arranged in one direction with respective main surfaces facing one another. According to the louver, light incident to the louver at a certain angle or more can be blocked.
The louver disclosed in Non-Patent Document 1, however, blocks a part of light having an angle at which light transmission is desired, that is, light incident to the louver at a small incidence angle. As a result, in order to increase the luminance of a display including this louver, it is required to increase an output of a light source.
On the other hand, Patent Document 1 discloses, as a panel for lighting equipment, a panel having a plurality of prism elements arranged therein as described above.
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As already described, in recent years, the display device has been mounted on the mobile unit typified by a vehicle, in order to display various information. For example, the display device includes a display device of the car navigation system of the vehicle, a display device for presenting information about vehicle driving to the driver, and the like. These display devices are positioned on the dashboard on the front side of the vehicle, for example. As described above, contents displayed by the display device may be reflected on the windshield adjacent to the dashboard. Such reflection is not preferable because the reflection obstructs the view of the driver of the vehicle. Thus, the use of the above light distribution control panel is considered in order to suppress such reflection. Patent Document 1, however, discloses an example of the light distribution control panel whose use mainly in outdoor lighting equipment is assumed. Patent Document 1 does not disclose preferable conditions and configuration of the light distribution control panel for suppressing the reflection on the glass surface of the display device mounted on the mobile unit as described above.
In the liquid crystal display panel disclosed in Patent Document 2, however, the louver film blocks light from the backlight. Thus, the front luminance of the display device decreases, and in addition, the efficiency of use of light is significantly low and the luminance of the panel display surface is insufficient. Therefore, the luminance of the backlight must be increased, and means for preventing an increase in electric power consumption and an increase in temperature of the liquid crystal display panel is required.
On the other hand, in the light distribution control sheet disclosed in Patent Document 1, the second light control means controls emission of light incident to the second light control means, toward the direction controlled by the first light control means. Therefore, the efficiency of use of light is enhanced and the front luminance can be maintained high. The peak of the luminance distribution as seen from the front of the sheet moves to a position that has shifted from the front to either right or left. In other words, the peak of the luminance distribution shifts in the direction in which the first light control means wants to control light.
In this light distribution control sheet, however, light also passes in a direction different from the direction in which the first light control means wants to control light. Therefore, light is also emitted to a viewing angle that is not required essentially. Accordingly, even if this light distribution control sheet is used in the display panel, it is expected that upward emission cannot all be prevented and reflection on the windshield of the vehicle cannot be sufficiently prevented.
On the other hand, the louver disclosed in Non-Patent Document 1 blocks a part of light having an angle at which light transmission is desired. As a result, in order to increase the luminance of the display including this louver, it is required to increase an output of the light source.
In addition, in order to apply the panel disclosed in Patent Document 1 to the display, it is required to decrease the cycle of each prism element to the order of several hundreds micrometers. Processing for roughening the second surface of the prism element having such a cycle is difficult or requires a highly sophisticated processing technique.
The present invention has been made to solve the above problems, and one object of the present invention is to provide a light distribution control panel that can suppress reflection on a glass surface in a mobile unit when the light distribution control panel is applied to a display device mounted on the mobile unit, and a display device for mounting on a mobile unit in which the light distribution control panel is used.
In addition, another object of the present invention is to achieve light distribution control for obtaining the relatively high front luminance and reducing emission to an unnecessary viewing angle.
Furthermore, still another object of the present invention is to provide an optical component having a viewing angle control function and having high efficiency of use of light. Moreover, a further object of the present invention is to provide a lighting device and a display device in which such an optical component is used.
Additionally, a further object of the present invention is to provide an optical component that controls the emission direction of light, has high efficiency of use of light and can be readily processed. In addition, a further object of the present invention is to provide a lighting device and a display device in which such an optical component is used.
A light distribution control panel according to the present invention is directed to a light distribution control panel, including a plate-like or sheet-like base material made of a translucent material, and the base material has a plurality of convex portions for light distribution control formed on one surface of the base material opposite to a light source side. The plurality of convex portions are positioned to extend in parallel to one another. The light distribution control panel includes a light transmission suppressing portion for suppressing emission, from at least a part of a surface of the convex portion, of light incident from a surface of the base material on the light source side.
With such a configuration, in a direction perpendicular to a direction in which the convex portion in the light distribution control panel extends, the light distribution of light passing through and emitted from the light distribution control panel can be controlled to be different on the right and left sides. For example, in a region of the convex portion on the one corner portion side of corner portions at opposite ends located at a boundary portion between the convex portion and the surface of the base material in a cross section in the above direction perpendicular to the direction in which the convex portion extends, the viewing angle at which a low luminance region having a reduced luminance (intensity) of light is formed can be relatively increased, whereas in a region of the convex portion on the other corner portion side, the viewing angle at which the low luminance region having a reduced luminance (intensity) of light is formed can be relatively decreased.
In the above light distribution control panel, the light transmission suppressing portion may include a light absorbing layer formed on the surface of the convex portion. In this case, the light absorbing layer can absorb at least a part of light emitted from the surface of the convex portion, and thus, the luminance of light in a direction in which the light emitted from the surface of the convex portion is released can be reduced. As a result, as for light emitted through a region where the light absorbing layer is formed, the viewing angle of a region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, the light transmission suppressing portion may include a different refractive index layer formed on the surface of the convex portion and having a refractive index different from a refractive index of a material that configures the convex portion. In this case, by adjusting the refractive index of the different refractive index layer, the emission direction of light emitted from the surface of the convex portion can be changed. Therefore, the luminance of light in a direction in which light emitted through a region where the different refractive index layer is formed travels when the different refractive index layer is not present can be reduced. As a result, in this direction, the viewing angle of the region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, the convex portion may have a triangle-like cross section in a direction perpendicular to a direction in which the convex portion extends. The light transmission suppressing portion may suppress emission of the light in the convex portion from one side surface that is continuous with any one of two corner portions located at a boundary portion between the convex portion and the surface of the base material in the cross section.
In this case, the convex portion can act as a prism. Therefore, by adjusting the angle of the corner portion located at the boundary portion between the convex portion and the surface of the base material in the cross section of the convex portion as well as the shape of the side surface that is continuous with the corner portion, the light distribution characteristics of light emitted from the surface (one surface opposite to the light source side of the base material) where the convex portion is formed in the light distribution control panel can be controlled. By using the light transmission suppressing portion to suppress the light emitted from the side surface that is continuous with one corner portion, the luminance of light in the direction in which the light emitted from the side surface that is continuous with the one corner portion is released can be reduced. Therefore, in this direction, the viewing angle of the region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, the light transmission suppressing portion may include a light source side light absorbing layer formed on a light source side surface of the base material to block at least a part of a path of light emitted from the one side surface, of light incident from the light source side surface to the base material when the light source side surface is flat. In this case, the light source side light absorbing layer can be absorb at least a part of light to be incident to one side surface. Therefore, the luminance of light in the direction in which the light emitted from the one side surface is released can be reduced. As a result, in this direction, the viewing angle of the region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, the light transmission suppressing portion may include a groove formed on a light source side surface of the base material to intersect a path of light emitted from the one side surface, of light incident from the light source side surface to the base material when the light source side surface is flat.
In this case, at least a part of light to be incident to one side surface can be reflected or refracted at the side surface of the groove. Therefore, the luminance of light in the direction in which the light emitted from the one side surface is released can be reduced. As a result, in this direction, the viewing angle of the region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, in the convex portion, roughness of the one side surface may be larger than roughness of the other side surface that is continuous with the other corner portion of the two corner portions. In this case, the light emitted from one side surface can be scattered at the one side surface. Therefore, the luminance of light in the direction in which the light emitted from the one side surface is released can be reduced. As a result, in this direction, the viewing angle of the region that forms the low luminance region can be effectively increased.
In the above light distribution control panel, a ratio (A/B) between roughness A of the one side surface that is continuous with one corner portion and roughness B of the other side surface that is continuous with the other corner portion may be 3 or more and 3000 or less. In this case, the light emitted from one side surface can be scattered more reliably.
In addition, the reason why the numerical range of the ratio (A/B) between surface roughness A of one side surface and roughness B of the other side surface is determined is that the above numerical range allows suppression of the amount of light reaching a glass surface (e.g., a glass surface at a driver's seat) of a mobile unit from a display device for mounting on a mobile unit to which the above light distribution control panel is applied, by setting the one side surface side to the glass surface side, when the display device is positioned in the proximity of the glass surface. Therefore, reflection of displayed contents on the glass surface can be sufficiently suppressed. It is noted that the ratio (A/B) is preferably set to 50 or more and 1000 or less.
In the above light distribution control panel, the other corner portion of the two corner portions may have an angle α of 5° or more and 40° or less, and the one corner portion may have an angle β of 60° or more and 90° or less. In this case, in the direction perpendicular to the direction in which the convex portion in the light distribution control panel extends, the light distribution of light passing through and emitted from the light distribution control panel can be reliably controlled to be different on the right and left sides.
In addition, the reason why the angle range of angle α is determined is that the angle range as described above allows prevention of reflection on the glass surface of an image displayed by the display device and suppression of degradation in front luminance of the display device to an acceptable range, when the light distribution control panel is applied to the above display device for mounting on a mobile unit. It is noted that angle α is preferably set to 10° or more and 30° or less.
Furthermore, the reason why the angle range of angle β is determined is that the angle range as described above allows suppression of leakage of light from the light distribution control panel to the glass surface side to a sufficiently low level, when the light distribution control panel is applied to the display device for mounting on a mobile unit. It is noted that angle β is preferably set to 60° or more and 90° or less.
In the above light distribution control panel, the base material may have a refractive index of 1.4 or more and 1.6 or less.
It is noted that the reason why the refractive index of the base material is set to 1.4 or more and 1.6 or less is that a material having such a refractive index is commonly available at low cost, which is effective at suppressing an increase in cost of the light distribution control panel. It is noted that the material may have a refractive index of 1.4 or more and 1.5 or less.
In addition, the light distribution control panel may have a light transmittance of 70% or more. It is noted that the reason why the light transmittance of the light distribution control panel is set to 70% or more is that an output of the light source required to maintain the luminance in a display surface of the display device at a fixed level can be suppressed by suppressing the light absorption rate in the light distribution control panel to be low, when the above light distribution control panel is applied to the display device, for example. For example, when the above light distribution control panel is applied to a liquid crystal display device, an output (luminance) of a backlight device needs to be made large enough to cover a loss in the light distribution control panel in order to ensure the sufficient luminance of the display surface if the light distribution control panel has a low light transmittance. By increasing the light transmittance of the light distribution control panel as described above, such a loss of light in the light distribution control panel can be decreased, which can result in a decrease in luminance of the backlight. As a result, the electric power consumption of the liquid crystal display device (display device) can be decreased, and thus, the power-saving and efficient display device can be implemented. It is noted that the light transmittance may be set to 80% or more.
In the above light distribution control panel, a width of the convex portion in the direction perpendicular to the direction in which the convex portion extends may be 20 μm or more and 500 μm or less. In addition, the lower limit of the width may be set to 50 μm or more and the upper limit of the width is preferably set to 100 μm or less. In this case, assuming that the light distribution control panel is applied to, for example, the display device and the like mounted on the mobile unit, the width (pitch) of the convex portion can be reduced to be less than or equal to the resolution of the human eye. Therefore, as for light that has passed through the light distribution control panel, recognition by human beings of the presence of the convex portion and an uncomfortable feeling about displayed contents displayed by using the light can be suppressed. In addition, by setting the above width to 100 μm or less, human beings hardly recognize the presence of the convex portion, and thus, the above effect can be reliably obtained.
It is noted that the reason why the lower limit of the pitch is set to 20 μm is to reduce, to a reasonable range, the manufacturing cost and the manufacturing time of a die used to manufacture the light distribution control panel.
The above light distribution control panel is directed to a light distribution control panel for a light source of a display device mounted on a mobile unit such as a vehicle. The effect of the present invention is particularly prominent when the light distribution control panel of the present invention is used in the light source of the display device mounted on the mobile unit in such a manner.
A display device for mounting on a mobile unit according to the present invention, includes: a light source; the above light distribution control panel; and a display unit. The light distribution control panel is positioned on the light source. The display unit is mounted on the light distribution control panel. With such a configuration, a direction in which arrival of light emitted from the display device is not desired can be configured as the low luminance region by adjusting the arrangement of the light distribution control panel (the direction in which the convex portion extends), when the display device is mounted on the mobile unit. Therefore, a defect due to the light emitted from the display device (e.g., reflection of a displayed image on a windshield) can be lessened.
The above display device for mounting on a mobile unit may be positioned at a site adjacent to a glass surface in a mobile unit, and the display device for mounting on a mobile unit may be positioned such that a direction perpendicular to a direction in which the convex portion extends matches a direction toward the glass surface. In this case, the direction toward the glass surface can be configured as the low luminance region, and thus, reflection on the glass surface of an image displayed by the display device can be suppressed.
A light distribution control panel according to the present invention is directed to a light distribution control panel, including a plate-like or sheet-like base material made of a translucent material, and the base material has a plurality of convex portions for light distribution control formed on one surface of the base material on a light source side. The plurality of convex portions are positioned to extend in parallel to one another and each has a triangle-like cross section in a direction perpendicular to a direction in which the convex portion extends. The base material has a refractive index of 1.4 or more and 1.6 or less. The light distribution control panel has a light transmittance of 70% or more. It is noted that the light transmittance herein refers to a transmittance of light having a wavelength of 400 nm or more and 700 nm or less. In the convex portion, one corner portion of two corner portions located at a boundary portion between the convex portion and a surface of the base material in the cross section has an angle β of 60° or more and 90° or less, and the other corner portion has an angle α of 5° or more and 40° or less. A ratio (A/B) between roughness A of one side surface of a surface of the convex portion that is continuous with the one corner portion and roughness B of the other side surface of the surface of the convex portion that is continuous with the other corner portion is 3 or more and 3000 or less.
With such a configuration, in the direction perpendicular to the direction in which the convex portion in the light distribution control panel extends, the light distribution of light passing through and emitted from the light distribution control panel can be controlled to be different on the right and left sides. For example, in a region of the convex portion on one corner portion side, the viewing angle of a low luminance region having a reduced luminance (intensity) of light can be relatively increased, whereas in a region of the convex portion on the other corner portion side, the viewing angle of the low luminance region having a reduced luminance (intensity) of light can be relatively decreased. In this case, the intensity of light passing through the light distribution control panel can be maintained, as compared with a configuration in which light traveling toward a region that should form the low luminance region is simply blocked.
It is noted that the reason why the refractive index of the base material is set to 1.4 or more and 1.6 or less is that a material which is commonly available at low cost has the above range of the refractive index. It is noted that the base material may have a refractive index of 1.45 or more and 1.55 or less.
In addition, the reason why the light transmittance of the light distribution control panel is set to 70% or more is that light emitted from a light source such as a backlight can be effectively made full use of, which allows a decrease in luminance of the mounted light source and electric power savings. It is noted that the light transmittance may be set to 80% or more.
Furthermore, the reason why the angle range of angle α is determined as described above is that this angle range allows prevention of reflection of an image on a windshield and allows light distribution without degrading the luminance (front luminance) on the front side of the light distribution control panel when the light distribution control panel according to the present invention is applied to the display device mounted on the mobile unit, as already described.
Moreover, the reason why the angle range of angle β is determined as described above is that this angle range allows sufficient suppression of leakage of light to the windshield, as already described. It is noted that angle β is preferably set to 70° or more and 90° or less.
Additionally, the reason why the numerical range of the ratio (A/B) between surface roughness A of one side surface and roughness B of the other side surface is determined is that this numerical range allows sufficient suppression of leakage of light to the windshield side as described above. It is noted that the ratio (A/B) is preferably set to 50 or more and 100 or less.
In the above light distribution control panel, a width of the convex portion in the direction perpendicular to the direction in which the convex portion extends may be 20 μm or more and 500 μm or less. In addition, the width is preferably set to 100 μm or less. In this case, assuming that the light distribution control panel is applied to, for example, the display device mounted on the mobile unit, the width (pitch) of the convex portion can be reduced to be less than or equal to the resolution of the human eye. Therefore, as for light that has passed through the light distribution control panel, recognition by human beings of the presence of the convex portion and an uncomfortable feeling about displayed contents displayed by using the light can be suppressed. In addition, by setting the above width to 100 μm or less, human beings hardly recognize the presence of the convex portion, and thus, the above effect can be reliably obtained.
It is noted that the reason why the lower limit of the pitch is set to 20 μm is that when the pitch is set to less than 20 μm, enormous manufacturing cost and manufacturing time of a die are required and manufacturing at practical manufacturing cost becomes difficult.
The above light distribution control panel is directed to a light distribution control panel for a light source of a display device mounted on a mobile unit such as a vehicle. The effect of the present invention is particularly prominent when the light distribution control panel of the present invention is used in the light source of the display device mounted on the mobile unit in such a manner.
A display device for mounting on a mobile unit according to the present invention includes: a light source; the above light distribution control panel; and a display unit. The light distribution control panel is positioned on the light source. The display unit is mounted on the light distribution control panel. With such a configuration, a direction in which arrival of light emitted from the display device is not desired can be configured as the low luminance region by adjusting the arrangement of the light distribution control panel (the direction in which the convex portion extends), when the display device is mounted on the mobile unit. Therefore, a defect due to the light emitted from the display device (e.g., reflection of a displayed image on a windshield) can be lessened.
The above display device for mounting on a mobile unit may be positioned at a site adjacent to a glass surface in a mobile unit, and the display device for mounting on a mobile unit may be positioned such that a direction perpendicular to a direction in which the convex portion extends matches a direction toward the glass surface. In this case, the direction toward the glass surface can be configured as the low luminance region, and thus, reflection of an image displayed by the display device on the glass surface can be suppressed.
In addition, a light distribution control sheet according to the present invention is directed to a light distribution control sheet including one or a plurality of linear convex portions on a translucent sheet-like base material. The convex portion has at least two light distribution control surfaces that each forms a different acute angle or right angle with respect to a surface of the base material. The light distribution control sheet includes a light control member provided on at least a part of a region of the light distribution control surface of the two light distribution control surfaces that forms a large angle with respect to the surface of the base material.
Furthermore, an optical component according to the present invention includes: a first lens array; a second lens array; and a light blocking portion array. The first lens array has a plurality of first lens elements arranged in one direction. The second lens array has a plurality of second lens elements arranged in one direction. The light blocking portion array has a plurality of light blocking portions arranged in one direction with a spacing therebetween. The plurality of first lens elements each has a convex incidence surface. The plurality of second lens elements each has a convex emission surface. The first lens array collects a part of incident light between the plurality of light blocking portions and couples the part of incident light to the second lens array, and couples, to any one of the plurality of light blocking portions, at least in part a different part of incident light incident at a larger angle with respect to an optical axis of the plurality of first lens elements than an angle formed by an incident direction of the part of incident light with respect to the optical axis.
According to the optical component of the present invention, of incident light, a part of light incident at a small angle with respect to the optical axis of the first lens element is collected by the first lens array between the light blocking portions and is emitted from the second lens array. On the other hand, incident light incident at a large angle with respect to the optical axis of the first lens element is blocked by the light blocking portion. In addition, since the second lens element has the convex emission surface, light coupled to the second lens array is emitted at a small angle with respect to an optical axis of the second lens element. Accordingly, in the present optical component, emitted light provides a small viewing angle and the efficiency of use of light emitted at a small angle with respect to the optical axis of the second lens element is enhanced.
In the optical component of the present invention, the light blocking portion is not preferably located on the optical axis of the plurality of first lens elements and on the optical axis of the second lens elements. In addition, in the optical component of the present invention, the light blocking portion is preferably located between a boundary between adjacent first lens elements and a boundary between adjacent second lens elements. Furthermore, the optical axis of the plurality of first lens elements matches the optical axis of the plurality of second lens elements. Cylindrical lenses can be used as the plurality of first lens elements and the plurality of second lens elements.
In addition, the present invention relates to a lighting device. This lighting device includes: a light source; and a light guiding plate for guiding, to the above optical component, light emitted from the light source. It is noted that the light guiding plate includes any members if the member has a light guiding function, and includes a diffusing plate, for example.
Furthermore, the present invention also relates to a display device. This display device includes: the above lighting device; and a liquid crystal panel for receiving light emitted from the lighting device and emitting the light.
Moreover, an optical component according to the present invention includes: a first prism array; and a second prism array. The first prism array has an incidence plane as well as a plurality of first surfaces and a plurality of second surfaces. The plurality of first surfaces and the plurality of second surfaces are provided alternately. The second prism array has an emission plane as well as a plurality of third surfaces and a plurality of fourth surfaces. The plurality of third surfaces and the plurality of fourth surfaces are provided alternately. Adjacent first surface and second surface extend along surfaces inclined with respect to the incidence plane and intersecting each other. An inclination angle formed by the plurality of first surfaces with respect to the incidence plane is smaller than an inclination angle formed by the plurality of second surfaces with respect to the incidence plane. The adjacent first surface and second surface as well as the incidence plane configure a prism element. Adjacent third surface and fourth surface extend along surfaces inclined with respect to the emission plane and intersecting each other. An inclination angle formed by the plurality of third surfaces with respect to the emission plane is smaller than an inclination angle formed by the plurality of fourth surfaces with respect to the emission plane. The adjacent third surface and fourth surface as well as the emission plane configure a prism element. The first prism array and the second prism array are spaced such that the first surface faces the third surface and the second surface faces the fourth surface. A refractive index of the first prism array and a refractive index of the second prism array are larger than a refractive index of a medium between the first prism array and the second prism array. The optical component of the present invention can emit light in a limited direction. In addition, the amount of light traveling toward a direction other than the direction, that is, a loss is small. Furthermore, this optical component eliminates the need for processing for surface roughening.
In the optical component of the present invention, an angle formed by the fourth surface with respect to the emission plane is preferably 85° or less. The medium may be a layer of air. The refractive index of the first prism array is preferably lower than the refractive index of the second prism array.
In addition, a lighting device of the present invention includes the above optical component of the present invention. Furthermore, a display device of the present invention includes the above optical component of the present invention.
According to the present invention, a decrease in intensity of light can be suppressed and the low luminance region can be formed in a particular direction of the viewing angle. Therefore, particularly when the present invention is applied to the display device for mounting on the mobile unit, reflection of an image on the adjacent glass surface and the like can be effectively suppressed.
In addition, according to the present invention, a decrease in intensity of light can be suppressed and the low luminance region can be formed in a particular direction of the viewing angle. Therefore, particularly when the present invention is applied to the display device for mounting on the mobile unit, reflection of an image on the adjacent glass surface and the like can be effectively suppressed.
Furthermore, according to the present invention, the light distribution control sheet has the linear convex portion having the two light distribution control surfaces that form different angles with respect to the surface of the base material. The light distribution control sheet includes the light control member provided at least the part of the region of the light distribution control surface that forms a large angle with respect to the foregoing surface of the base material, of the foregoing two light distribution control surfaces. Therefore, the high front luminance is maintained, and in addition, the light distribution characteristics to either right or left visual field are enhanced and emission to the other visual field, that is, unnecessary viewing angle is almost suppressed.
Moreover, according to the present invention, there is provided an optical component having a viewing angle control function and high efficiency of use of light. Additionally, according to the present invention, there is provided a lighting device and a display device in which this optical component is used.
Besides, according to the present invention, there is provided an optical component that controls the emission direction of light, has high efficiency of use of light and can be readily processed. In addition, according to the present invention, there is provided a lighting device and a display device in which such an optical component is used.
Embodiments of the present invention will be described hereinafter with reference to the drawings. The same or corresponding portions are denoted with the same reference characters in the following drawings, and description thereof will not be repeated.
A light distribution control panel according to the present invention, a display device, and a vehicle serving as a mobile unit on which the display device is mounted will be described hereinafter with reference to
As shown in
The characteristic configuration of above light distribution control panel 1 is summarized as follows: light distribution control panel 1 includes base body 7 serving as a plate-like or sheet-like base material made of a translucent material, and base body 7 has the plurality of convex portions 2 serving as convexly-shaped portions for light distribution control formed on one surface opposite to the light source (a backlight 11) side of base body 7. The plurality of convex portions 2 are positioned to extend in parallel to one another as shown in
The plurality of convex portions 2 each has a triangle-like cross-sectional shape in the direction perpendicular to the direction in which convex portion 2 extends. Although convex portion 2 may have a triangular cross-sectional shape as shown in
Base body 7 has a refractive index of 1.4 or more and 1.6 or less. Light distribution control panel 1 has a light transmittance of 70% or more. In convex portion 2, the other corner portion 3 that is the other corner portion of the two corner portions located at the boundary portion between convex portion 2 and the surface of base body 7 in the above cross section has angle α of 5° or more and 40° or less, and one corner portion 4 that is one corner portion has angle β of 60° or more and 90° or less. The ratio (A/B) between roughness A of one side surface 6 that is continuous with one corner portion 4 in the surface of convex portion 2 and roughness B of the other side surface 5 that is continuous with the other corner portion 3 in the surface of convex portion 2 is 3 or more and 3000 or less.
With such a configuration, in the direction perpendicular to the direction in which convex portion 2 in light distribution control panel 1 extends, the light distribution (luminance distribution) of light passing through and emitted from light distribution control panel 1 can be controlled to be different on the right and left sides as shown in
In above light distribution control panel 1, pitch P that is the width of convex portion 2 in the direction perpendicular to the direction in which convex portion 2 extends is 20 μm or more and 500 μm or less. Preferably, pitch P is set to 100 μm or less. In this case, assuming that light distribution control panel 1 is, for example, applied to a display device 10 for mounting on the mobile unit as will be described later, recognition by human beings of the presence of convex portion 2 and an uncomfortable feeling about displayed contents can be suppressed as for light that has passed through light distribution control panel 1. This is because the width (pitch P) of convex portion 2 can be reduced to be less than or equal to the resolution of the human eye. In addition, when above pitch P is set to 100 μm or less, human beings hardly recognize the presence of convex portion 2, and thus, the above effect can be reliably obtained.
Next, a method for manufacturing above light distribution control panel 1 by molding through the use of a die will be described hereinafter.
In the method for manufacturing light distribution control panel 1, a die having a concave portion corresponding to the surface shape of light distribution control panel 1 formed therein is first prepared. A thin film made of a resin that will configure light distribution control panel 1 is set between this die and an opposite surface plate. In this state, the thin film made of a resin is heated. Thereafter, molding is performed by pressing the heated thin film made of a resin to be sandwiched by the die and the opposite surface plate. After cooled, the thin film made of a resin is removed from the die. As a result, light distribution control panel 1 shown in
As a method for heating the thin film made of a resin, a method for sandwiching the thin film made of a resin between the die and the opposite surface plate and then heating the thin film made of a resin, a method for heating only the thin film made of a resin in a non-contact state in advance, and the like can be arbitrarily employed. The thin film made of a resin can be heated by a heater and the like placed directly below the die and the opposite surface plate. The thin film made of a resin, however, can also be heated by using a heating function introduced into the die and the opposite surface plate (the heater and the like is placed inside the die and the opposite surface plate).
The thin film made of a resin is preferably heated to be higher than or equal to a temperature at which the resin starts to be liquefied. The thin film made of a resin is heated to be higher than or equal to the temperature at which the resin starts to be liquefied as described above, and then, is subjected to pressurization processing to press the thin film made of a resin by the die and the opposite surface plate. As a result, by using the phenomenon where the resin is liquefied, the shape of the concave portion formed in a surface of the die can be transferred to a surface of the thin film made of a resin. In such a manner, light distribution control panel 1 according to the present invention can be manufactured.
The use, as the resin that will configure light distribution control panel 1, of a resin that melts in a relatively narrow temperature range and rapidly cures when cooled is preferable because the throughput is increased. Accordingly, polycarbonate, polyimide, polymethylmethacrylate, polyether sulfone, polysulfone, polyetherimide, and the like are suitable. Although the thickness of the thin film made of a resin is not particularly limited, the thickness is preferably set to 20 μm or more, and more preferably 100 μm or more.
The die used to form light distribution control panel 1 can be manufactured by using any conventionally well-known methods. For example, the die can be manufactured by using a method including the steps of: forming a resin die by molding; forming a layer made of a metallic material on the resin die on a substrate by plating; and removing the resin die.
At this time, a parent die used in the step of forming the resin die by molding can be manufactured by, for example, machining. Specifically, a thick NiP (nickel phosphorus)-plated layer is formed on a base plate, for example. Then, a surface of the plated layer is subjected to cutting processing by a cutting tool having a tip shape corresponding to the surface shape of light distribution control panel 1 (cross-sectional shape of convex portion 2). In such a manner, the above parent die can be formed. As the parent die, a precise microstructure can be used. In this case, a child die manufactured by the parent die is also a precise microstructure. Therefore, minute molding with high dimensional accuracy can be performed on the thin film made of a resin. In addition, because of molding through the use of the die, a molded body can be integrally molded with good reproducibility. Furthermore, the surface roughness (Ra) of the molded body can also be suppressed to 10 nm or less.
The method for manufacturing the die by using the above molding will be specifically described hereinafter. First, by using the die (parent die) having a convex portion, molding such as injection molding is performed to manufacture the resin die having a concave-convex portion. The resin die is made of polymethylmethacrylate, polypropylene, polycarbonate, or the like. Next, a conductive substrate is formed to cover a top portion of the resin die, and then, the resin die is polished or ground. As a result of this polishing or grinding, a base portion of the resin die is removed, thereby achieving a state where a pattern made of the resin is formed on a surface of the conductive substrate. In other words, the resin die having the conductive substrate as a base is formed.
Thereafter, by using the conductive substrate as a plating electrode, electroforming is performed to deposit the metallic material layer on the resin die. A prescribed thickness of the metallic material layer is obtained by polishing or grinding as required, and then, the resin die is removed by wet etching or plasma ashing. As a result, the die having the conductive substrate as the base and having the metallic material layer formed on the surface of the conductive substrate in a prescribed pattern is obtained. In this die, the conductive substrate is used as the seat (base) of the die, and thus, the electroforming time required to form the seat can be saved. In addition, since the seat is not formed by electroforming, only a small amount of warpage occurs in the die due to internal stress.
The above die can also be manufactured by using another method. The method will be specifically described hereinafter.
First, by using the die (parent die) having the convex portion, molding is performed to manufacture the resin die. Next, the metallic material layer is formed on the resin die by electroless plating. Thereafter, the resin die is removed by wet etching or plasma ashing. As a result, the die is obtained.
Light distribution control panel 1 shown in
As shown in
Backlight 11 may be configured such that a diffusing plate and a luminance assisting film are positioned on the light distribution control panel 1 side. In addition, an LCD unit, for example, can be used as display unit 12. The LCD unit includes, for example, a liquid crystal cell, a phase difference plate positioned on each of the front surface and the back surface of the liquid crystal cell, and a polarizing plate positioned on the outer circumferential surface of each phase difference plate. The liquid crystal cell has a structure in which liquid crystals and a thin-film transistor for driving the liquid crystals are positioned between two substrates of glass positioned to face each other with a spacer interposed therebetween. It is noted that a unit having another configuration may be used as display unit 12 if the unit passes and uses light from backlight 11. In addition, as a different arrangement of light distribution control panel 1, light distribution control panel 1 may be positioned on display unit 12 (on a surface of display unit 12 opposite to a surface (back surface) on the backlight 11 side.
With such a configuration, by appropriately adjusting the shape of convex portion 2 (see
Display device 10 shown in
Referring to
A second embodiment of the light distribution control panel according to the present invention will be described with reference to
Light distribution control panel 1 shown in
Convex portion 2 of light distribution control panel 1 shown in
Next, a method for manufacturing light distribution control panel 1 shown in
A modification of the light distribution control panel shown in
Light distribution control panel 1 shown in
It is noted that light distribution control panel 1 shown in
A third embodiment of the light distribution control panel according to the present invention will be described with reference to
Light distribution control panel 1 shown in
Convex portion 2 of light distribution control panel 1 shown in
It is noted that light distribution control panel 1 shown in
A modification of the light distribution control panel shown in
Light distribution control panel 1 shown in
Convex portion 2 of light distribution control panel 1 shown in
It is noted that light distribution control panel 1 shown in
A light distribution control panel 101 according to the present invention will be described with reference to
As shown in
The characteristic configuration of above light distribution control panel 101 is summarized as follows: light distribution control panel 101 includes base body 107 serving as a plate-like or sheet-like base material made of a translucent material, and base body 107 has the plurality of convex portions 102 serving as a linear and convexly-shaped portion for light distribution control formed on one surface on the light source (a backlight 111) side of base body 107. The plurality of convex portions 102 are positioned to extend in parallel to one another, and each convex portion 102 has a triangle-like cross-sectional shape in the direction perpendicular to the direction in which convex portion 102 extends. Although convex portion 102 may have a triangular cross-sectional shape as shown in
With such a configuration, in the direction perpendicular to the direction in which convex portion 102 in light distribution control panel 101 extends, the light distribution (luminance distribution) of light passing through and emitted from light distribution control panel 101 can be controlled to be different on the right and left sides as shown in
In above light distribution control panel 101, pitch P that is the width of convex portion 102 in the direction perpendicular to the direction in which convex portion 102 extends is 20 μm or more and 500 μm or less. Preferably, pitch P is set to 100 μm or less. In this case, assuming that light distribution control panel 101 is, for example, applied to a display device 110 for mounting on the mobile unit as will be described later, recognition by human beings of the presence of convex portion 102 and an uncomfortable feeling about displayed contents can be suppressed as for light that has passed through light distribution control panel 101. This is because the width (pitch P) of convex portion 102 can be reduced to be less than or equal to the resolution of the human eye. In addition, when above pitch P is set to 100 μm or less, human beings hardly recognize the presence of convex portion 102, and thus, the above effect can be reliably obtained.
Light distribution control panel 101 shown in
As shown in
With such a configuration, by appropriately adjusting the shape of convex portion 102 (see
Display device 110 shown in
Referring to
The following simulation experiment was carried out to check the effect of the light distribution control panel according to the present invention.
(As to Experimental System)
As a system assumed in the simulation experiment, an optical system was used in which light distribution control panel 101 according to the present invention was positioned such that convex portion 102 faced the front (light emitting side) of backlight 111 as shown in
Specifically, angle β of one corner portion was changed to 70°, 75°, 80°, 85°, and 90° with angle α of the other corner portion fixed and with angle α of the other corner portion set to 15°, 20°, 25°, and 30°.
It is noted that the refractive index of the material that configured the light distribution control panel was set to 1.53. In addition, thickness T of base body 107 (see
(Details of Simulation)
The viewing angle distribution of the relative luminance was calculated for the optical systems in which light distribution control panels 101 having different convex portions 102 as described above were used.
(Results)
In
As described above, by controlling angle α of the other corner portion and angle β of one corner portion, the range of the low luminance region can be changed. This result shows that according to the light distribution control panel of the present invention, the low luminance region having a range sufficient to suppress reflection on the glass surface in the display device for mounting on the mobile unit is obtained, and a decrease in luminance can be suppressed in the other region (luminance ensuring region).
A light distribution control panel 201 shown in
Light distribution control sheet 210 has a linear convex portion 212 on one surface of a translucent plate-like or sheet-like base material 211, and is referred to as a so-called prism sheet or prism array. In light distribution control panel 201 shown in
Linear convex portion 212 in the present invention refers to linearly-extending and elongated convex portion 212, and means that at least one, and preferably multiple convex portions 212 are disposed in parallel. Light distribution control panel 201 includes convex portion 212 having preferably the same length and width as the sheet width (corresponding to the depth of the sheet in the figure) as shown in
In this light distribution control sheet 210, base material 211 and convex portion 212 are integrally formed of a translucent material such as glass, a polycarbonate resin and a polyimide resin, for example. In particular, minute convex portion 212 is required to deal with an increase in resolution of liquid crystal panel 220. In order to achieve this, a resin material that allows transfer by using a die having a minute transfer pattern formed thereon is suitably used.
Light distribution control sheet 210 shown in
Further, in light distribution control sheet 210 of the present invention, the light distribution control surface that forms a larger angle with respect to the base material surface, that is, second light distribution control surface 214 in the illustrated example includes a light control member 215. This light control member 215 suppresses light transmission and reflection of second light distribution control surface 214, and reduces the luminance in the unnecessary viewing angle. This light control member 215 is not particularly limited if light control member 215 is a film that suppresses transmission and reflection. For example, light control member 215 is formed of a black film that absorbs light in the visible region or an antireflective film such as a silicon oxide film. When light control member 215 is formed of the black film, light control member 215 may be formed by, for example, deposition of graphite. When light control member 215 is formed of the antireflective film, light control member 215 may be formed by, for example, sputtering silicon oxide. In addition, by forming the black film in a necessary region of the die having the above minute transfer pattern formed therein, the transfer pattern can also be transferred. As for this light control member 215, only a reduction in luminance in the unnecessary viewing angle is insufficient, and suppression of the luminance to almost zero is desired. Accordingly, the light diffusing surface as disclosed in Patent Document 2 is insufficient, and the black film that absorbs light or the antireflective film such as the silicon oxide film as described above is desirable. As a matter of course, any configuration is possible if light control member 215 can suppress the luminance in the unnecessary viewing angle to almost zero.
It is desirable to form this light control member 215 preferably all over second light distribution control surface 214. This light control member 215 may, however, be formed on a part of the region if light control member 215 can reduce the luminance in the unnecessary viewing angle, and desirably can suppress the luminance in the unnecessary viewing angle to almost zero.
Solid line A in
As indicated by broken line C in
When second light distribution control surface 214 includes light control member 215 formed of a light blocking film or the antireflective film as in the present invention, a central axis of the luminance distribution shifts to one visual field side and light tailing to the other visual field side is cut, although the effect of cutting (shaping up) the spread of light as in the case where the louver film is used is not produced. In other words, when light distribution control sheet 210 having the structure shown in
Angle α formed by first light distribution control surface 213 and the base material surface as well as angle β formed by second light distribution control surface 214 and the base material surface are each appropriately set depending on the required light distribution characteristics. By changing these angle α and angle β, the viewing angle at which a dark region is formed, that is, the angle at which the luminance becomes almost zero can be adjusted. It is noted that the luminance in the viewing angle at which the luminance decreases tends to depend on the accuracy of formation of light control member 215, so to speak, the light transmission degree (light blocking degree) and the light reflection degree of light control member 215. By forming light control member 215 with good accuracy, the luminance in the unnecessary viewing angle approaches almost zero. When the light blocking performance and the light reflection performance of light control member 215 deteriorate, the luminance does not become zero. As can also be seen from the following simulation, in order to suppress the luminance to zero on the unnecessary viewing angle side, the smaller angle, that is, angle α formed by first light distribution control surface 213 and the base material surface is preferably set to 5° or more and 40° or less, and the larger angle, that is, angle β formed by second light distribution control surface 214 and the base material surface is preferably set to 60° or more and less than 90°. By adjusting angle α and angle β within this range, the luminance in the range of an angle (one side) larger than a desired viewing angle can be suppressed to almost zero.
As a matter of course, in light distribution control sheet 210 of the present invention, convex portion 212 may be positioned not only on the light source side as shown in
According to this simulation, it is understood that in light distribution control sheet 210 of the present invention, the luminance becomes almost zero in the range of the emission angle of +25° or more without depending on angle α formed by first light distribution control surface 213 and the base material surface as well as angle β formed by second light distribution control surface 214 and the base material surface.
For example, light distribution control panel 201 of the present invention is used in the display device for mounting on the mobile unit, for example, display device 10 of the car navigation system shown in
Although the case where convex portion 212 has a triangular end surface has been described in the above embodiment, convex portion 212 may be formed to have a substantially trapezoidal end surface in which convex portion 212 has a third light distribution control surface 216 on the light emission side as shown in
First light distribution control surface 213 and second light distribution control surface 214 are generally formed to have a planar shape as shown in
Although light distribution control panel 201 as an image display panel including backlight 230 has been described in the above embodiment, a self-light-emitting image display panel (not shown) can also be used in the present invention. Unlike the display panel that displays an image on liquid crystal display panel 220 by using above backlight 230, the self-light-emitting image display panel does not require backlight 230 and allows display of an image by using, as a light source, an illuminant provided within the image display panel. Light distribution control sheet 210 of the present invention is also applicable to such a self-light-emitting image display panel, and is also applicable to both of an organic EL panel in which an organic material (organic Electroluminescence) is used as the illuminant and an inorganic EL panel in which an inorganic material (inorganic Electroluminescence) is used as the illuminant. Light distribution control sheet 210 is positioned on the image display surface side of the self-light-emitting image display panel. At this time, light distribution control sheet 210 can be positioned such that convex portion 212 faces the image display surface side or the light emission side. As described above, the image display panel is used in the present invention in a broad sense including various types of image display panels such as the liquid crystal panel in which the backlight light source is used, the self-light-emitting display panel including the organic EL panel and the inorganic EL panel. By combining the image display panel and the light distribution control sheet of the present invention, the light distribution characteristics can be further enhanced.
An optical component 310 shown in
First lens array 312 includes a plurality of first lens elements 312a. The plurality of first lens elements 312a are arranged in one direction, that is, in the x direction. First lens elements 312a each includes a convex incidence surface 312b. In other words, first lens element 312a has a convex surface on the opposite side of a boundary between light blocking portion array 316 and this first lens element 312a. In the present embodiment, each of first lens elements 312a is a cylindrical lens.
Second lens array 314 includes a plurality of second lens elements 314a. The plurality of second lens elements 314a are also arranged in one direction. In the present embodiment, the plurality of second lens elements 314a are also arranged in the x direction. In other words, second lens elements 314a are arranged in the same direction as the direction in which the plurality of first lens elements 312a are arranged. Second lens elements 314a each includes a convex emission surface 314b. In other words, second lens element 314a has a convex surface on the opposite side of a boundary between light blocking portion array 316 and this second lens element 314a. In the present embodiment, each of second lens elements 314a is also the cylindrical lens.
Light blocking portion array 316 has a plurality of light blocking portions 316a. In the present embodiment, the plurality of light blocking portions 316a each has a plate-like shape. The plurality of light blocking portions 316a are arranged in one direction with spacings therebetween. In the present embodiment, the plurality of light blocking portions 316a are arranged in the same direction as the direction in which the plurality of first lens elements 312a are arranged. In addition, the plurality of light blocking portions 316a extend along a surface that intersects the direction in which the plurality of light blocking portions 316a are arranged. In light blocking portion array 316 of the present embodiment, a member, for example a resin, transparent to incident light is filled with a space 316b between adjacent light blocking portions 316a.
In the present embodiment, the cycle of the plurality of first lens elements 312a, the cycle of the plurality of second lens elements 314a, and the cycle of the plurality of light blocking portions 316a are all the same. In addition, light blocking portion 316a is provided between a boundary between adjacent first lens elements 312a and a boundary between adjacent second lens elements 314a. Furthermore, a position of the boundary between adjacent first lens elements 312a in the direction in which these first lens elements 312a are arranged matches a position of the boundary between adjacent second lens elements 314a in the direction in which these second lens elements 314a are arranged. In other words, an optical axis of first lens element 312a matches an optical axis of second lens element 314a.
A path of light incident to the present optical component will be described in detail hereinafter. In
As shown in
On the other hand, light L3 that forms a larger angle with respect to optical axis Z1 than light L1 and light L2, of the light incident to optical component 310, is coupled to light blocking portion 316a. Accordingly, light L3 is blocked by light blocking portion 316a and is not coupled to second lens element 314a.
In such a manner, in optical component 310, the incident light incident at a small angle with respect to optical axis Z1 of first lens element 312a can be coupled to second lens array 314, without blocked by light blocking portion 316a. In addition, the light incident to second lens array 314 is emitted such that the emission direction forms a small angle with respect to optical axis Z2. Accordingly, optical component 310 can narrow the viewing angle, and the loss of unnecessary light due to light blocking portion 316a can be reduced, which can enhance the efficiency of use of light.
In
The characteristics for the optical component of the present embodiment shown in
thickness of the first lens element on the optical axis: 0.3 mm;
the first lens element and the second lens element: cylindrical lens;
curvatures of the incidence surface of the first lens element and the emission surface of the second lens element: 0.5 mm;
shapes of the emission surface of the first lens element and the incidence surface of the second lens element: planar;
cycles of the first lens element and the second lens element: 0.6 mm;
distance between the first lens element and the second lens element: 1.2 mm;
material of the first lens element: polycarbonate (refractive index: 1.59);
material of the second lens element: polycarbonate (refractive index: 1.59);
thickness of the light blocking portion: 50 μm;
length of the light blocking portion: 1 mm;
cycle of the light blocking portion: 0.6 mm;
material of the light blocking portion: black-colored silicone rubber; and
material of the space between the light blocking portions: silicone rubber (refractive index: 1.43).
As is clear from
The suitable embodiments of the present invention have been described above. In the optical component of the present invention, a spacing between adjacent light blocking portions, a spacing between adjacent first lens elements, and a spacing between adjacent second lens elements are preferably equal. In addition, the first lens element and the second lens element preferably have the positive power in the z-x plane.
Furthermore, the boundary position in the direction in which adjacent first lens elements are arranged preferably matches the position of the light blocking portion in the direction in which adjacent first lens elements are arranged. It is noted that a manner in which the light blocking portion is located on the optical axis of the first lens element is not preferable because light incident at a small angle with respect to the optical axis of the first lens element is blocked. The boundary position in the direction in which adjacent first lens elements are arranged may be slightly shifted from the position of the light blocking portion in the direction in which adjacent first lens elements are arranged.
Moreover, the shape of the first lens element and the shape of the second lens element may be the same or different from each other. The length of the light blocking portion in the z direction may be equal to the distance from the first lens array to the second lens array, or may be shorter than this distance. In order to efficiently block light incident at a large angle with respect to the optical axis of the first lens element, the length of the light blocking portion in the z direction needs to be at least about a half of the distance from the first lens array to the second lens array.
The light blocking portion preferably has a transmittance of 0% in a wavelength (e.g., 400 to 700 nm) of incident light. Even if the light blocking portion has a transmittance of about 10%, the desired effect of the present optical component is obtained.
In addition, the cycle of the plurality of light blocking portions may be N times (N is an integer of 1 or more) of the cycle of the plurality of first lens elements and the cycle of the plurality of second lens elements. In an optical component 310A shown in
Furthermore, the cycle of the plurality of light blocking portions may be partially different from the cycle of the plurality of first lens elements and the cycle of the plurality of second lens elements. In an optical component 310B shown in
Moreover, the direction in which the plurality of second lens elements are arranged may be different from the direction in which the plurality of first lens elements are arranged and the direction in which the plurality of light blocking portions are arranged. In an optical component 310C shown in
Additionally, the light blocking portion may be inclined with respect to the optical axis of the first lens element. In an optical component 310D shown in
Besides, the boundary position between adjacent second lens elements may not match the boundary position between adjacent first lens elements, in the arrangement direction. In an optical component 310E shown in
A display device in which the above optical component is used will be described hereinafter. A display device 320 shown in
A display device 320A shown in
Optical component 410 shown in
First prism array 412 has an incidence plane 412a, a plurality of first surfaces 412b and a plurality of second surfaces 412c. Incidence plane 412a is a surface which light from the light source enters, and substantially forms a plane.
First surface 412b and second surface 412c are alternately provided. Adjacent first surface 412b and second surface 412c extend along two surfaces that intersect incidence plane 412a and intersect each other, respectively. An angle α1 formed by first surface 412b with respect to incidence plane 412a is smaller than an angle β1 formed by second surface 412c with respect to incidence plane 412a. In first prism array 412 having such a surface configuration, incidence plane 412a and adjacent first surface 412b and second surface 412c configure the prism element. In first prism array 412, the prism elements configured in such a manner are arranged in one direction (x direction). In such a manner, first prism array 412 has a plurality of prism elements, and the cycle in the direction in which the prism elements are arranged can be set to approximately several hundred micrometers.
Second prism array 414 has an emission plane 414a, a plurality of third surfaces 414b and a plurality of fourth surfaces 414c. Emission plane 414a is a surface from which the light incident to this optical component 410 is emitted outside, and substantially forms a plane.
Third surface 414b and fourth surface 414c are also alternately provided. Adjacent third surface 414b and fourth surface 414c extend along two surfaces that intersect emission plane 414a and intersect each other, respectively. An angle α2 formed by third surface 414b with respect to emission plane 414a is smaller than an angle β2 formed by fourth surface 414c with respect to emission plane 414a. In second prism array 414 having such a surface configuration, emission plane 414a and adjacent third surface 414b and fourth surface 414c configure the prism element. In second prism array 414, the prism elements configured in such a manner are arranged in one direction (x direction). In such a manner, second prism array 414 has a plurality of prism elements, and the cycle in the direction in which the prism elements are arranged can be set to approximately several hundred micrometers.
First prism array 412 and second prism array 414 are spaced such that first surface 412b faces third surface 414b and second surface 412c faces fourth surface 414c. In the present embodiment, first prism array 412 and second prism array 414 are provided such that the sum of a distance t1 from incidence plane 412a of first prism array 412 to a side where first surface 412b intersects second surface 412c and a distance t2 from emission plane 414a of second prism array 414 to a side where third surface 414b intersects fourth surface 414c becomes smaller than a distance t between incidence plane 412a and emission plane 414a.
A medium 416 is provided between first prism array 412 and second prism array 414 provided in such a manner. An air layer or an adhesive layer can be used as medium 416. A refractive index n1 of first prism array 412 and a refractive index n2 of second prism array 414 are larger than a refractive index n0 of this medium 416.
In optical component 410, if first prism array 412 is the same as second prism array 414, most of incident light beam is emitted at an angle equal to the incidence angle. Accordingly, any one of α1≠α2, β1≠β2, and n1≠n2 needs to be satisfied.
A path of light incident to such optical component 410 will be described hereinafter.
As shown in
In addition, as shown in
On the other hand, as shown in
According to the Snell's law, the relationship between incidence angle i and emission angle θ7 is as described in the following expressions:
sin(i)=n1×sin θ1
θ2=θ1+α1
n1×sin(θ2)=n0×sin(θ3)
θ4=θ3−α1+α2
n0×sin(θ4)=n2×sin(θ5)
θ6=θ5−α2
n2×sin(θ6)=sin(θ7). (1)
As incidence angle i is increased until θ2 reaches a critical angle, emission angle θ7 is also increased. Therefore, emission angle θ7 of light beam L having the path as shown in
sin(iR)=n1×sin(sin−1(n0/n1)−α1))
Next, a path of light entering incidence plane 412a and reaching second surface 412c or fourth surface 414c will be described.
As shown in
On the other hand, as shown in
In addition, as shown in
The path of light in optical component 410 has been described above with reference to
According to the Snell's law, the relationship between incidence angle j of light beam L shown in
sin(j)=n1×sin(γ1)
γ2=γ1−α1
n
1×sin(γ2)=n0×sin(γ3)
γ4=γ3+α1−α2
n
0×sin(γ4)=n2×sin(γ5)
γ6=180°−γ5−α2−β2
γ7=β2−γ6
n
2×sin(γ7)=sin(γ8).
As is clear from
In addition, as is clear from
In
The angle distribution of the luminance shown in
cycle of the prism element: 0.3 mm;
α1=17°;
β1=89°;
α2=16°;
β2=76°;
t1=0.25 mm;
t2=0.25 mm;
t=0.44 mm;
medium 416: air layer;
refractive index of the first prism array: 1.4; and
refractive index of the second prism array: 1.6.
As shown in
A display device in which the above optical component is used will be described hereinafter. A display device 420 shown in
It should be understood that the embodiments and examples disclosed herein are illustrative and not limitative in any respect. The scope of the present invention is defined by the terms of the claims, rather than the above description, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
The present invention is advantageously applied to a display device mounted on a mobile unit, in particular, a display device positioned adjacent to a glass surface, and a light distribution control panel used in the display device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 208-107778 | Apr 2008 | JP | national |
| 2008-177103 | Jul 2008 | JP | national |
| 2008-177121 | Jul 2008 | JP | national |
| 2008-198408 | Jul 2008 | JP | national |
| 2009-002968 | Jan 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/057496 | 4/14/2009 | WO | 00 | 2/9/2011 |
