JP2010267524A - Lighting device and display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: in a conventional configuration in which a prism sheet is placed on an emission surface that emits diffusion light having a brightness peak at the front to distribute emitted light in two directions, the control of the direction of light coming out of the emission surface is difficult, which results in lower light use efficiency. <P>SOLUTION: A light guide plate 2 guides light from a light source 1 to cause light having vertical directivity to come out of the emission surface of the light guide plate 2, on which a prism sheet 3 is disposed to distribute light coming out of the emission surface in specific two directions. To align beams of light guided through the light guide plate 2, an incoming light portion of the light guide plate 2 has an incoming light surface 2a with a recession formed thereon and a paraboloid connected to the incoming light surface 2a. A reflection structure is disposed on the undersurface of the light guide plate 2, so that light is guided vertically to the emission surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lighting device and a display device used for an electronic device. In particular, the present invention relates to a liquid crystal display device used in a car navigation system, a liquid crystal television, and the like, and an illumination device such as a front light and a backlight that illuminate a non-self-luminous display element. The present invention also relates to equipment lighting equipment for residences and offices.

  Conventionally, when there are observers in two specific directions, such as a driver's seat and a passenger's seat, as in a car navigation system, an illumination device that appears brightest from the two directions has been proposed. In such an illuminating device, a prism sheet having a prism with an apex angle of about 90 ° is arranged on the light exit surface of the surface light source so that light is emitted in two directions so that the apex angle of the prism faces the light exit surface. Is known to distribute light (see, for example, Patent Document 1).

JP 2000-164016 A

  In the illumination device disclosed in FIG. 2 of Patent Document 1, light diffused from the center of the light exit surface of the light guide is emitted so as to have a luminance peak in front of the light exit surface. In the lighting device having such a light distribution characteristic, the light emitted from the light guide does not have directivity in a specific direction, so it is difficult to control the light emission direction. For this reason, when the prism sheet is disposed on the light guide, the light emitted from the light guide cannot be efficiently incident on the prism sheet, and the luminance of the lighting device tends to decrease. Further, the direction of light distributed by the prism sheet is limited to a certain angle.

  Furthermore, since the lighting device having such a light distribution characteristic requires a plurality of optical films to be disposed on the light output surface of the light guide, the thickness of the lighting device is increased and the manufacturing cost is increased. Further, since these optical films and the prism sheet are overlapped, there is a problem that the prism of the prism sheet is rubbed when the illumination device vibrates.

  In order to solve the above-described problems, an illumination device according to the present invention includes a light source and a light guide that enters light from the light source from a side surface and emits light in a vertical direction from the upper surface. A prism sheet that distributes the emitted light in two directions is arranged. Further, a concave portion is formed on the light incident surface of the light guide so as to face the light source, and a parabolic surface extending radially from the light emitting portion of the light source in the light emitting direction is connected to the light incident surface. A prism is disposed on the opposite surface of the light guide opposite to the exit surface, and light from the light incident surface is reflected by this prism and emitted in the vertical direction.

  Furthermore, the angle and intensity of the light transmitted through the prism sheet were corrected by providing a prism on the exit surface of the light guide.

  ADVANTAGE OF THE INVENTION According to this invention, the light radiate | emitted from the output surface of a light guide can be controlled, and the high-intensity and thin illuminating device which utilized light efficiently can be provided. In addition, the angle and intensity of light distributed by the prism sheet can be adjusted.

It is a schematic diagram which shows the structure of the illuminating device of this invention. It is an enlarged view which shows typically a part of structure of the illuminating device of this invention. It is a schematic diagram which shows the structure of the illuminating device of this invention. It is a schematic diagram explaining the light-incidence part of the illuminating device of this invention. It is an enlarged view which shows typically a part of structure of the illuminating device of this invention. It is a schematic diagram which shows the cross-sectional structure of the illuminating device of this invention. It is a schematic diagram which shows a part of structure of the illuminating device of this invention. It is a figure which shows the behavior of the light of the illuminating device of this invention.

  The illuminating device of this invention is demonstrated based on FIGS. 1-3. FIG. 1 is an overhead view schematically showing the illumination device of the present invention. As shown in the figure, the light emitted from the emission surface is specified on the emission surface of the light guide 2 that guides light from the light source 1 and emits light having directivity in the vertical direction from the emission surface. A prism sheet 3 that distributes light in the direction is provided. The light guide 2 can be roughly divided into a light incident part 2a and a light emitting part. The light incident part 2 a includes a light incident surface facing the light outgoing part of the light source 1 and a parabolic surface formed in a parabolic shape from the light outgoing part of the light source 1 in the light outgoing direction. As shown in the figure, when a plurality of light sources are provided, a paraboloid is formed in the light incident portion 2a facing the interval between the light sources 1. Further, the light source 1 is disposed in the vicinity of the light incident surface of the light incident portion 2a. The light guide 2 guides the light incident from the light incident surface of the light incident portion 2a and emits it from the light emitting surface of the light emitting portion. A concave portion is formed on the light incident surface of the light incident portion 2 a so as to face the light exit portion of the light source 1. Light from the light source 1 is aligned in a certain direction in the light incident part 2a and introduced into the light guide 2, and light having directivity is emitted in the vertical direction from the emission surface.

  FIG. 2 is a side view of the illumination device of FIG. 1 as viewed from the rear of the light source. As shown in the figure, a prism sheet 3 that distributes light from the exit surface of the light guide 2 in two directions is disposed above the exit surface of the light guide 2. The prism sheet 3 is disposed so that the apex angle of the prism faces the light exit surface of the light guide 2. FIG. 3 is an enlarged view of a part of FIG. 2 and shows the behavior of light of the present lighting device. The light emitted from the light source 1 enters the light guide 2, exits almost perpendicularly from the exit surface 2 e of the light guide 2, and enters the prism sheet 3. The prism of the prism sheet 3 has a function of distributing light emitted from the emission surface 2e in two directions. The apex angle of the prism of the prism sheet 3 is desirably 60 degrees to 110 degrees. Of the outgoing light 7 having a vertical light component, the light hitting the inclined surface 3a constituting the prism is refracted to become outgoing light 7a, which is emitted from the upper surface of the prism sheet. Similarly, of the outgoing light 7, the light hitting the inclined surface 3 b constituting the prism is also refracted to become outgoing light 7 b, which is emitted from the upper surface of the prism sheet. In this way, the outgoing light 7 having a vertical light component is distributed in two specific directions by the prism of the prism sheet, and is emitted from the prism sheet 3.

  Next, a configuration in which light emitted from the light source 1 is emitted almost vertically from the emission surface 2e of the light guide 2 will be described with reference to FIG. As described above, the light incident part is composed of the light incident surface and the paraboloid in which the concave portion is formed, so that the light of the light source that emits light in a wide range is aligned in a certain direction inside the light guide 2. It can be introduced. The light guide 2 is formed with a reflective structure for emitting light incident from the light incident surface from the light exit surface. The light that is aligned in a certain direction by the light incident part is reflected by this reflecting structure and is emitted vertically from the emission surface of the light guide 2.

  At this time, the height may be changed by setting the pitches of the reflecting structures at regular intervals. That is, the height of the reflecting structure is increased as the distance from the light source increases. Alternatively, the height of the reflecting structure may be constant and the pitch may be variable. That is, the pitch of the reflecting structure is reduced as the distance from the light source increases.

  In addition, a second reflecting structure that corrects the direction and intensity of light from the exit surface is provided between the exit surface of the light guide 2 and the prism sheet 3. An upper prism that is substantially perpendicular to the light incident surface of the light guide may be formed on the exit surface of the light guide 2 to form the second reflective structure. The apex angle of the upper prism is in the range of 40 ° to 170 °. The upper prism is desirably formed not only on the entire surface of the light emitting portion of the light guide 2 but also on the light incident portion. The upper prism may be formed as close as possible to the light source. At this time, a prism having a shape different from the shape of the prism formed on the exit surface of the light emitting portion is formed in the light incident portion. The upper prism of the light incident part is shaped so that the directions of light emitted from the light incident part are aligned, and the upper prism of the light emitting part is shaped so as to correct the direction and intensity of light from the emission surface.

  The display device of the present invention is configured to illuminate a non-self-luminous display element with the illumination device having any one of the above-described configurations.

  This embodiment will be described with reference to FIGS. In FIG. 4, the shape of the light incident part 2a of the light guide 2 is enlarged and shown. As shown in the drawing, a trapezoidal concave portion 2 b is provided on the light incident surface facing the light source 1. The short side of the trapezoid is 0.2 to 0.6 mm, the long side is about 1.0 to 1.2 mm, the height is about 0.5 to 1.0 mm, and the optimum value depends on the light distribution characteristics of the light source 1 and the like. . In addition, a parabolic surface 2d extends in a parabolic shape from the light output portion of the light source 1 along the light output direction. The curve of the paraboloid 2d is determined by the focal position of the parabola that forms the paraboloid 2d, and the focal position is in the range of approximately 0.5 to 0.7 mm horizontally from the light source 1 along the emission surface. The shape of the recess, the parabola and the focal position thereof are optimized according to the light distribution characteristics of the light source 1. In this embodiment, the concave shape is trapezoidal, but the same effect can be obtained even if the shape is a semicircle, a triangle, or a polygon. Further, in this embodiment, the paraboloid 2d is formed by a curved surface, but it may be formed by a plurality of planes combined at an angle to have a polygonal shape. When the paraboloid 2d has a polygonal shape, the light distribution can be freely controlled, and a higher-luminance and higher-uniform illumination device can be realized.

  Reflective structures such as prisms and dots are formed on the exit surface and the opposing surface of the light guide 2. The light that has entered the light guide 2 travels while guiding the inside of the light guide, and exits from the exit surface of the light guide 2 by hitting the reflection structure. The light incident portion 2a of the present embodiment causes more light components that exit perpendicularly from the exit surface (in other words, toward the observer) to enter the light guide when hitting the reflecting structure. Can do. The light incident portion 2a has a function of converting the direction of some components while dividing the light of the light source 1 into three directions. The light emitted from the light source 1 collides with the trapezoidal concave portion 2b, enters the light guide 2 from the short side of the trapezoid, and refracts from the two oblique sides of the trapezoid and the linear component 8a that travels in a straight line. It is divided into components that enter light. This component hits the paraboloid 2d, and many of the components are totally reflected to become the reflection component 8b, and travel in substantially the same direction as the straight component 8a. That is, by providing the trapezoidal concave portion 2b and the parabolic surface 2d on the light incident surface of the light incident portion, the direction of light from the light source 1 can be aligned. The focal length of the paraboloid 2d is about 0.5 to 0.7 mm from the light source 1. The light of the rectilinear component 8a and the reflection component 8b hits the reflection structure formed in the light guide 2 and is emitted from the emission surface.

  Next, FIG. 5 schematically shows a main part of an illumination device in which a lower prism is formed on the opposite surface of the light guide as a reflective structure. Since the light entrance 2 is formed with the light incident portion 2 a described above, most of the light emitted from the light source 1 is a component perpendicular to the lower prism 5. Light in a direction perpendicular to the top line of the lower prism 5 is reflected by the lower prism 5 and is emitted perpendicularly from the emission surface. Therefore, the light output efficiency from the light guide can be made extremely high.

FIG. 6 schematically shows a cross-sectional configuration of the illumination device having the light guide 2 on which the lower prism 5 is formed.
The light guide 2 has an exit surface 2e and a facing surface. Above the exit surface 2e, the prism sheet 3 is arranged such that the prism apex angle of the prism sheet 3 faces the exit surface 2e. The prism of the prism sheet 3 has an apex angle of approximately 60 ° to 110 °. Basically, the smaller the prism apex angle, the wider the relative angle of light distributed in two directions, and the wider the apex angle, the narrower the relative angle of light distributed in two directions. When the apex angle of the prism is less than 60 degrees, most of the light that is emitted from the light guide 2 and is perpendicular to the exit surface is reflected by the inclined surface that forms the prism, so that the intensity of light distributed in two directions is weakened. In addition, when the prism apex angle is 110 ° or more, when the light is guided into the prism sheet, the change in the angle of the light becomes small, and it becomes difficult to clearly distribute the light in two directions.

  Below the facing surface of the light guide 2, a reflection sheet 4 is installed. The reflection sheet 4 is often a type in which silver or aluminum is vapor-deposited on a transparent film such as PET, white PET, ESR manufactured by Sumitomo 3M, or the like. The frame 6 was used to mechanically support the light source 1, the light guide 2, and the reflection sheet 4, and to prevent leakage light and improve the light utilization efficiency. That is, the reflective sheet 4 is disposed on the frame 6, and the light guide 2 is disposed so that the reflective surface of the reflective sheet 4 faces the opposing surface. The frame 6 is often a resin molded product such as white polycarbonate. The frame 6 may be further covered with a metal frame such as aluminum.

  The lower prism 5 is a concave portion formed on the lower surface (opposing surface) of the light guide 2 and is composed of at least two surfaces. Of these two surfaces, the surface close to the light source 1 is the reflecting surface 2f. As described above, the light incident on the light guide 2 from the light source 1 is divided into the straight component 8a and the reflective component 8b, and strikes the lower prism 5 perpendicular to the top line of the lower prism 5. Therefore, many components are easily emitted from the emission surface 2e. Further, if the prism angle (the angle formed by the reflecting surface 2f of the lower prism 5 and the light emitting surface 2e) is in the range of 40 to 50 degrees, many components are reflected on the reflecting surface 2f of the lower prism 5 and the light guide. 2 is totally reflected in a direction perpendicular to the exit surface 2e of the second. In this embodiment, the pitch of the lower prism 5 is set to be equal and the height is changed. The lower the prism 5 is, the lower the distance from the light source 1, and the higher the distance from the light source 1. When used in combination with a light guide formed with a prism and a liquid crystal panel, there may be a prism pitch that easily interferes with the dot pitch of the liquid crystal panel. If the pitch is constant as in this embodiment, there is an advantage that it is easy to avoid interference with the liquid crystal panel.

  On the other hand, when the height of the lower prism 5 has to be very small depending on the thickness and size of the light guide 2, on the contrary, the height of the reflecting structure is made constant and the pitch can be made variable. An effect can be obtained.

  With the configuration as described above, the emission direction of the light emitted from the emission surface 2e of the light guide 2 is aligned in the vertical direction, and the light can be efficiently incident on the prism sheet.

  The illumination device of the present embodiment is different from the first embodiment in that a prism is provided on the light exit surface 2e of the light guide 2, and is the same as the first embodiment in other structures. FIG. 7 schematically shows a configuration in which a prism is formed on the light exit surface 2 e of the light guide 2. As shown in the drawing, an upper prism 9 having an arrangement direction orthogonal to the arrangement direction of the lower prism 5 is formed on the emission surface 2 e of the light guide 2. By forming the upper prism 9 as described above, the direction and intensity of light emitted from the light guide 2 and incident on the prism sheet 3 can be corrected.

  The apex angle of the upper prism 9 may be set in a wide range of 40 ° to 170 °. The upper prism 9 is desirably formed not only on the entire surface of the light emitting portion of the light guide 2 but also on the upper surface of the light incident portion 2a. That is, it is desirable to form as close to the light source 1 as possible. By forming the upper prism 9 up to the upper surface of the light incident part 2a, the straight component 8a and the reflection component 8b can be mixed more uniformly. The optimum value of the upper prism apex angle for uniformly mixing the straight component 8a and the reflection component 8b, and the upper prism apex angle for correcting the direction and intensity of light incident from the light guide 2 to the prism sheet 3 The value is often different. Therefore, if the upper prism shape provided on the upper surface (light guide 2 near the light source 1) of the light incident part 2a and the upper prism shape provided on the light emitting part of the light guide 2 are individually optimized, good. That is, the apex angle of the prism formed on the upper surface of the light incident part near the light source is set so as to align the direction of the light emitted from the light incident part, and the apex angle of the prism formed on the upper surface of the light emitting part is the output surface It is set to correct the direction and intensity of the light emitted from 2e.

  The behavior of the light of the illumination device in the present embodiment is shown in FIGS. As shown in the drawing, an upper prism is provided on the exit surface 2e of the light guide 2, and the apex angles of the upper prisms are different from each other. 8A and 8B, the upper prism of FIG. 8A is formed to have a larger apex angle. When the apex angle of the upper prism of the light guide 2 is increased, the emitted light 7 has many light components perpendicular to the emitting surface 2e, as shown in FIG. 8A. The outgoing light 7 enters the prism sheet 3 perpendicularly and is distributed by the prism sheet 3 in two specific directions.

  On the other hand, if the apex angle of the upper prism is reduced, the viewing angle of the emitted light 7 from the light guide 2 can be widened as shown in FIG. 8B, and the relative angle of the two directions of light emitted from the prism sheet 3 can be increased. Can be bigger.

  Thus, by adjusting the magnitude of the apex angle of the upper prism, it is possible to change the angle of light in two directions distributed by the prism sheet 3.

  In FIG. 8C, the apex angle of the upper prism is tilted from the direction perpendicular to the exit surface 2e of the light guide 2. Thereby, the component of the outgoing light 7 from the light guide 2 can be tilted from the direction perpendicular to the outgoing surface 2e, and the intensity of the light distributed in two directions through the prism sheet 3 can be changed. it can.

  The illumination device and the display device according to the present invention can be applied to display devices such as a mobile phone, a PDA, a car navigation system, and a television. It can also be applied to equipment lighting equipment such as a residence or office.

DESCRIPTION OF SYMBOLS 1 Light source 2 Light guide 2a Light incident part 2b Recessed part 2d Parabolic surface 2e Output surface 2f Reflective surface 3 Prism sheet 4 Reflective sheet 5 Lower prism 6 Frame 7 Output light 8a Straight component 8b Reflective component 9 Upper prism

Claims (7)

A light source;
A light guide that aligns light from the light source in a certain direction at the light incident portion and introduces the light into the inside, and emits light having directivity in the vertical direction from the emission surface;
An illumination device comprising: a prism sheet disposed above the light guide and distributing light emitted from the light guide in two specific directions. A concave portion is provided on the light incident surface of the light incident portion so as to face the light emission portion of the light source,
The lighting device according to claim 1, wherein the light incident portion includes a paraboloid extending on a parabola in a light exit direction from the light incident portion of the light source and the light exit portion of the light source. A reflective structure is formed on the lower surface of the light guide,
The illumination device according to claim 1, wherein the reflection structure reflects light introduced from the light incident portion and emits the light vertically from the emission surface.   4. The prism according to claim 1, wherein a prism having an apex angle of 60 to 110 degrees is formed on the prism sheet, and the apex angle is disposed so as to face an emission surface of the light guide. The lighting device according to claim 1.   The lighting device according to claim 1, wherein a plurality of upper prisms are formed on the emission surface in a direction orthogonal to the light incident surface.   The said upper prism is also formed in the said light incident part, The shape of the upper prism formed in the said output surface and the upper prism formed in the said light incident part differs. Lighting device. A light source;
A light guide that aligns light from the light source in a certain direction at the light incident portion and introduces the light into the inside, and emits light having directivity in the vertical direction from the emission surface;
A non-self-luminous display element disposed above the light guide;
A display device comprising: a prism sheet that is disposed between the light guide and the display element and distributes light emitted from the light guide in two specific directions.

Images