JP5460440B2 - Illumination device and display device - Google Patents

Description

  The present invention relates to a technique suitable for use in a lighting device and a display device.

Electronic paper is known as a reflective display that reflects external light and performs display. This electronic paper refers to a display medium that has the visibility and portability, which are the advantages of paper, and can electrically rewrite display contents. Electronic paper is being adopted for electronic book readers and the like because of the above advantages.
An electrophoretic technique is a typical display technique for electronic paper. In this method, an electrophoretic element is sandwiched between a pixel substrate and an element substrate on which a thin film transistor for driving the pixel electrode is formed and a counter substrate in which a transparent electrode (counter electrode) is uniformly formed on a transparent substrate. Configuration is adopted. With this configuration, an image can be formed by applying a desired potential difference between the transparent electrode and the pixel electrode. In this method, an image is generally viewed from the side of the counter electrode formed by a transparent electrode (for example, Patent Documents 1 and 2).
In addition to the above-described electrophoretic technique, there is a technique that uses a cholesteric liquid crystal that selectively reflects light of different wavelengths to enable multicolor display.

  Unlike the transmissive display, the reflective display using the above-described electronic paper or a so-called reflective liquid crystal display device performs display by reflecting external light such as fluorescent light or sunlight. For this reason, it cannot be used in a dark environment, and a front light may be provided for display illumination.

US Pat. No. 6,067,185 JP 2003-107535 A JP 2007-052930 A

However, a front light used for an electronic book reader in which portability is more important than a notebook PC or the like is required to be thin and light. In addition, in electronic paper or the like that employs an electrophoresis method, power is consumed only when the display content is changed, so that the proportion of illumination in the power consumption of the entire apparatus is relatively large. For this reason, the power consumption reduction request | requirement with respect to a front light is strong.
Further, the front light is required to have high light transmittance. This is because if the light transmittance of the front light is impaired, the visibility of the display screen is greatly reduced even if the degree is small. In particular, the decrease in visibility when the front light is not turned on is significant.

In an electronic book reader, it is necessary to ensure good visibility even in a use environment without sufficient light. For that purpose, high brightness of the front light is required, but at the same time, uniformity of brightness is also required. For example, the entire display screen of about A4 size is uniformly illuminated with high brightness so that it is under sunlight. It was difficult to provide high visibility.
For example, when a light guide plate having a concavo-convex surface is used as a front light as in Patent Document 2, the display screen is visually recognized through the concavo-convex portion, and the reduction in visibility and display nonuniformity cannot be ignored.
Also, as in Patent Document 3, if a structure having a scratched flat surface is used to give sufficient brightness, the scratched part reflects light from the light source and shines. The visible part interfered with the display, and the visibility was significantly reduced.
Thus, an illumination device having both visibility and portability has not been proposed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an illumination device having both visibility and portability and a display device on which the illumination device is mounted.

The lighting device of the present invention is a lighting device including a light guide plate capable of covering at least a part of a plate-shaped display medium, and a light source provided on an end surface of the light guide plate,
The non-facing surface, which is the surface opposite to the side facing the display medium of the light guide plate, is provided with a dot-like reflecting recess having a reflecting surface inclined toward the light source with respect to the non-facing surface, The light transmitted by the light guide plate is reflected by the reflecting surface of the dot-like reflecting recess to illuminate the display medium,
The aperture ratio of the dot-like reflection recess is set to 0.5 to 5%, the shape of the dot-like reflection recess in plan view is a substantially rectangular shape, and its aspect ratio is 1: 1. the surface roughness of the reflecting surface, solves the above problems by the following der Rukoto 1 [mu] m.
In the illumination device of the present invention, the reflecting surface of the dot-shaped reflective concave portion, to the non-facing surface of the light guide plate, it is a Turkey inclined at 80 degrees or less than 30 degrees.
In addition, a means in which the opening size of the dot-like reflection concave portion is set to 1 μm to 1 mm can be employed.
In the illuminating device of the present invention, it is desirable that the pitch of the dot-shaped reflective recesses is set to 1 μm to 1 mm.
In the illumination device of the present invention, the display medium can be a liquid crystal display device or an electrophoretic display device.
The display device of the present invention is a display device comprising a plate-shaped display unit, a light guide plate capable of covering at least a part of the display unit, and a light source provided on an end surface of the light guide plate,
The light guide plate is provided with a dot-like reflective recess having a reflective surface inclined to the light source side with respect to the non-facing surface on a non-facing surface opposite to the side facing the display medium. The light transmitted by the light plate is reflected by the reflecting surface of the dot-like reflecting recess to illuminate the display unit,
The aperture ratio of the dot-like reflection recess is set to 0.5 to 5% , the shape of the dot-like reflection recess in plan view is a substantially rectangular shape, and its aspect ratio is 1: 1. surface roughness of the reflective surface of the can below der Rukoto 1 [mu] m.
In the display device of the present invention, the reflecting surface of the dot-shaped reflective concave portion, to the non-facing surface of the light guide plate, it is a Turkey inclined at 80 degrees or less than 30 degrees.
In addition, a means in which the opening size of the dot-like reflection concave portion is set to 1 μm to 1 mm can be employed.
In the display device according to the aspect of the invention, it is preferable that the pitch of the dot-like reflective recesses is set to 1 μm to 1 mm.
In the display device of the present invention, the display unit can be constituted by a liquid crystal display device or an electrophoretic display device.

  ADVANTAGE OF THE INVENTION According to this invention, the illuminating device which has visibility and portability, and a display apparatus which mounts it can be provided.

1 is a perspective view showing a first embodiment of a display device according to the present invention. It is an expanded sectional side view which shows the dot-shaped reflective recessed part in 1st Embodiment of the display apparatus which concerns on this invention. It is an enlarged front view which shows the dot-shaped reflective recessed part in 1st Embodiment of the display apparatus which concerns on this invention. It is an enlarged front view which shows the other example of arrangement | positioning of a dot-shaped reflective recessed part. It is an enlarged front view which shows the other example of arrangement | positioning of a dot-shaped reflective recessed part. It is a typical sectional side view which shows 2nd Embodiment of the display apparatus which concerns on this invention. It is a perspective view which shows 2nd Embodiment of the display apparatus which concerns on this invention. It is operation | movement explanatory drawing of an electrophoretic element. It is a typical sectional side view which shows 3rd Embodiment of the display apparatus which concerns on this invention. It is a perspective view which shows 4th Embodiment of the display apparatus which concerns on this invention. It is a typical sectional side view which shows 5th Embodiment of the display apparatus which concerns on this invention. It is a typical sectional side view which shows 5th Embodiment of the display apparatus which concerns on this invention. It is a model front view which shows 5th Embodiment of the display apparatus which concerns on this invention. It is an enlarged front view which shows the other example of arrangement | positioning of a dot-shaped reflective recessed part.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment relating to an illumination device according to the invention will be described with reference to the drawings.
As shown in FIG. 1, the illumination device 10 according to the present embodiment includes a transparent light guide plate 11 and a light source 14 that is provided on an end surface 11 a of the light guide plate 11 and emits light toward the light guide plate 11.

As the light source 14, an LED, a fluorescent lamp, an incandescent lamp, a mercury lamp, a rod-shaped light guide, or the like can be used. The light source 14 is preferably formed so as to extend along the extending direction of the light guide plate 11. In FIG. 1, the light source 14 is formed to extend along the end surface 11 a on one side of the substantially rectangular light guide plate 11.
As the light source 14, for example, a plurality of LEDs arranged in a direction along the end surface 11a can be used. Moreover, the light emitted from the light source 14 can be exemplified by white light, daylight light, warm color light, and the like, and can be appropriately selected according to the object to be illuminated. The light source 14 can also be provided on the other end surface of the light guide plate 11. The light source 14 is connected to a power source and a light emission control unit (not shown).

  The light guide plate 11 may be a material that is transparent to light of the wavelength used, and a plate made of a synthetic resin such as an acrylic resin, a polycarbonate resin, a silicon resin, a cyclopolyolefin resin, or a glass plate is used. Among these, an acrylic plate is preferable from the viewpoints of transparency and ease of processing. Moreover, as a manufacturing method of the light guide plate 11, a method capable of forming the shape of a dot-like reflective recess 12 described later is employed. That is, for example, injection molding or cutting, a method of pressing the blade in a heated state disclosed in Patent Document 3, and the like are employed. In the injection molding, a light guide plate having a thickness of about 0.3 to 0.5 mm can be manufactured.

  The thickness of the light guide plate 11 can be, for example, in the range of 0.3 mm to 2 mm. It is preferable that the thickness of the light guide plate 11 is uniform throughout the light guide plate 11. Further, as shown in FIG. 2, the light guide plate 11 has a visible light transparency that does not deteriorate the visibility of a display medium to be illuminated (not shown) that is close to the back surface (opposing surface) 11 c side, that is, transparent. It is preferable that Moreover, in the case of this embodiment, although the light-guide plate 11 is substantially rectangular shape, it is not limited to this. That is, the shape of the light guide plate 11 is arbitrary as long as even the end face 11a on which the light from the light source 14 is incident can be formed. In the drawing, the back surface 11c of the light guide plate 11 is a surface facing the display medium, and the front surface 11b is the surface on the opposite side and the surface on the observer side.

A plurality of dot-like reflective recesses 12 are uniformly formed on the entire surface (non-opposing surface) 11b.
As shown in FIG. 2 and the like, the dot-like reflective recess 12 is a cutout formed in the surface 11b, and reflects the light L1 incident on the light guide plate 11 from the end surface 11a to the back surface 11c as reflected light L2. 12a. In FIG. 2, light in the main optical axis direction is described as the incident light L1. The reflected light L2 is also described as corresponding to it. In this example, the main optical axis direction is a direction orthogonal to the end face 11a. As will be described later, the dot-like reflective recess 12 is shaped so that the incident light L1 strikes the reflective surface 12a. In addition, as shown in FIG. 2 etc., the direction orthogonal to the end surface 11a is hereafter called c direction. The light guide plate thickness direction orthogonal to the c direction is hereinafter referred to as the t direction. Hereinafter, a direction orthogonal to both the c direction and the t direction is referred to as an r direction.

  In the present embodiment, as shown in FIG. 2, the dot-like reflective recesses 12 are formed in a V shape having a cross section of the light guide plate 11 along the direction of the incident light L1 and the reflective surface 12a as a hypotenuse. As shown in FIG. 3, it is substantially rectangular in plan view. In addition, this planar view shape is also the shape of the opening part of the dot-shaped reflective recessed part 12. FIG.

  The aspect ratio (aspect ratio) of the dot-shaped reflective recess 12 in plan view (rectangular shape) is preferably in the range of 10: 1 to 1: 1, and more preferably in the range of 5: 1 to 1: 1. However, the aspect ratio is most preferably 1: 1. Here, the aspect ratio refers to a ratio between a long side and a short side of a rectangle having a minimum area that is inscribed by the dot-like reflective recess 12 in plan view. In the present embodiment, the shape of the dot-like reflective recess 2 in plan view is a rectangle, and the aspect ratio is the ratio of the long side to the short side of the rectangle (long side: short side). If the aspect ratio is large, the dot-shaped reflective concave portion 12 is easily noticeable to the observer, and as a result, the visibility is lowered, which is not preferable. In the present embodiment, for example, the rectangular shape of the dot-like reflective recess 2 is arranged in parallel with the end face 11a.

  The reflecting surface 12a is inclined toward the light source 14 with respect to the surface 11b. As shown in FIG. 2, the inclination angle α of the reflecting surface 12a with respect to the surface 11b is set so as to efficiently reflect the incident light L1 to the display medium side.

  The inclination angle α is preferably 30 degrees or greater and 80 degrees or less. In addition, when making the output direction of the reflected light L2 into the direction t which is a light-guide plate thickness direction, the inclination | tilt angle (alpha) of the reflective surface 12a has preferable 40 to 60 degree | times. On the other hand, since the emission direction of the reflected light L2 may be shifted from the direction t, the inclination angle α is preferably in the range of 30 degrees to 80 degrees.

Although the inclination angle α of the reflection surface 12a can be made uniform over the entire back surface 11b of the light guide plate 11, it is not limited to this. The reflective surfaces 12a of the respective dot-like reflective recesses 12 can be made parallel to each other, but are not limited thereto. For example, as shown in FIG. 14, the reflective surface 12 a can be directed to the center of the light guide plate 11 in the vicinity of the edge 11 e of the light guide plate 11. Thereby, the reflected light L <b> 2 comes to the center of the light guide plate 11 in this vicinity.
In the illustrated example, the reflecting surface 12a is a flat surface, but is not limited thereto. The reflection surface 12a may be any surface that can obtain a sufficient illumination effect on the display medium without leaking extra light to the surface 11b side.

  The surface roughness (maximum height Ry) (JIS B 0601-1994) of the reflecting surface 12a is 1 μm or less, preferably 0.1 μm or less. By setting the surface roughness within this range, the light reflection efficiency on the reflecting surface 12a can be increased.

  If the depth γ (FIG. 2) of the dot-like reflecting recess 12 is too small, the reflected light on the back surface 11c side is small and the illumination effect is insufficient, and if too large, the dot-like reflection of light from the display medium is too large. Due to the reflection and scattering in the unnecessary direction by the recess 12, the transparency is impaired and the visibility of the display is lowered. Therefore, the depth γ of the dot-like reflective recess 12 is preferably 1 μm to 1 mm, and more preferably 10 μm to 200 μm. The depth γ of the dot-like reflecting recess 12 may be uniform throughout the light guide plate 11 or not.

As shown in FIG. 3, if the long side length β1 of the dot-like reflective recess 12 is too small, the reflected light to the back surface 11c side is small and the illumination effect is insufficient, and if it is too large, the transparency is impaired. Display visibility is reduced. Therefore, the long side length β1 is preferably 1 μm to 1 mm, and more preferably 10 μm to 200 μm.
Moreover, as shown in FIG. 3, the short side length β2 of the dot-like reflective recess 12 is preferably 1 μm to 1 mm, and more preferably 10 μm to 200 μm. The reason is the same as the long side length β1.
The long side length β1 and the short side length β2 are the long side length and the short side length of the opening portion of the dot-like reflective recess 12. Therefore, when these are not particularly distinguished, they are hereinafter referred to as opening sizes as appropriate.

  The pitch p1 (FIG. 3) in the direction c of the dot-shaped reflective recess 12 and the pitch p2 in the direction r are both preferably set to 1 μm to 1 mm, and more preferably set to 10 μm to 300 μm. .

Note that these pitches p1 and p2 can be equal or different. In any case, these pitches are related to an aperture ratio K, which will be described later, of the dot-like reflective recess 12, and the aperture ratio K is set to be in the range of 0.5 to 5%.
If the area of all the dot-like reflection recesses 2 is constant, the intensity of the reflected light in the dot-like reflection recesses 12 located far from the light source 14 tends to be lower than the reflected light in the dot-like reflection recesses 12 close to the light source 14. There is. In order to compensate for this decrease in reflected light intensity, the pitches p1 and p2 can be changed according to the distance from the light source 14. More specifically, it is preferable to reduce at least one of the pitch p1 and the pitch p2 of the dot-like reflective recess 12 according to the distance from the light source 14.

The aperture ratio K of the dot-like reflective recess 12 is preferably set in the range of 0.5 to 5%, more preferably 0.75 to 3.5%.
Here, the aperture ratio K is the ratio of the area of the dot-like reflective recess 12 per unit area on the front surface 11b (or the back surface 11c) of the light guide plate 11. That is, the number (density) of the dot-shaped reflective recesses 12 formed per unit area on the front surface 11b (or the back surface 11c) is n / cm ^2, and the long-side length β1 and the short-side length β2 of the dot-shaped reflective recesses 12 are set. Is constant, the aperture ratio K can be expressed as n × β1 × β2, and when the pitch of the dot-like reflective recesses 12 is constant, the aperture ratio K is (β1 × β2) / (p1 × p2). It is expressed.

  If the aperture ratio K of the dot-like reflective recess 12 is smaller than the above range, the area of the reflective surface 12a cannot be secured sufficiently, so that sufficient reflected light cannot be obtained, resulting in dark lighting. Moreover, when the aperture ratio K of the dot-shaped reflection recessed part 12 is larger than said range, the dot-shaped reflection recessed part 12 will become easy to be visually recognized from the surface 11b side, and visibility will fall.

In the illuminating device 10 of this embodiment, the light from the light source 14 transmitted by the light guide plate 11 is efficiently reflected by the reflecting surface 12a of the dot-like reflecting recess 12 and emitted from the back surface 11c. For this reason, a plate-shaped display medium (not shown) placed in contact with or close to the back surface 11c of the illumination device 10 can be illuminated with uniform irradiation light.
Therefore, the luminance per unit area of the display medium can be sufficiently increased without substantially blocking the observer's line of sight from the surface 11b side. For this reason, excellent visibility can be obtained even when the surroundings are dark or observation is performed at a distance from the display medium. Moreover, by suppressing the area and density of the dot-shaped reflection recessed part 12 to said range, the transparency of the illuminating device 10 becomes high and the visibility of a display is hardly impaired.

  In the present embodiment, as shown in FIG. 4, it is possible to provide the row of dot-like reflective recesses 12 shifted in the r direction by, for example, the short side length β2. Furthermore, as shown in FIG. 5, it is possible to provide a row of dot-like reflective recesses 12 on the right side of the right-side row in the drawing while being shifted in the r direction opposite to the example of FIG. Similarly, it is possible to arrange the rows of dot-like reflective recesses 12 side by side. By arranging the dot-like reflective recesses 12 so as not to overlap as seen from the light source 14 side as described above, it is possible to prevent the reflected light from decreasing at a position away from the light source 14. Further, the rows of dot-like reflective recesses 12 can be arranged so as to be alternately shifted in the r direction.

Further, in the present embodiment, the dot-like reflective recesses 12 are provided uniformly distributed over the entire back surface 11c. For example, the dot-like reflective recess 12 may be provided only on a specific portion of the back surface 11c, or may be provided so as to be rough or dense on a part of the back surface 11c. For example, it is possible to compensate for luminance by increasing the density at the peripheral portion far from the light source 14.
It is also possible to provide the dot-like reflective recess 12 only on a part of the back surface 11c. The light guide plate 11 may be curved as well as flat. For example, it may be curved into any shape such as a cylinder according to the shape of the object to be illuminated.

  In the present embodiment, a protective layer can be provided on the surface 11b side. With such a configuration, it is possible to prevent dust and the like from directly attaching to the light guide plate 11 and to suppress unnecessary light from being visually recognized due to light scattering. Further, the protective layer can be made of a material having a refractive index lower than that of the light guide plate 11. For example, when the light guide plate 11 is made of an acrylic resin, a silicon-based resin, a fluorine-based resin, or the like having a lower refractive index than the acrylic resin can be used as the protective layer material. Thereby, even when fine dust adheres to the surface 11b, light in the light guide plate 11 can be prevented from leaking and visibility being lowered. The protective layer can be formed by a screen printing method, a dipping method, or the like.

Hereinafter, a second embodiment related to a display device according to the present invention will be described with reference to the drawings.
FIG. 6 is a schematic side sectional view showing the display device 20 in the present embodiment, FIG. 7 is a schematic perspective view showing the display device 20 in the present embodiment, and reference numeral 6 denotes a display unit to be irradiated. In the present embodiment, components corresponding to the configurations shown in the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

  In the display device 20 of the present embodiment, as shown in FIG. The illuminating device 10 is disposed on the front side of the display area 60 of the display unit 6 as a display medium so that the entire display area 60 can be illuminated by reflected light emitted from the back surface 11c side. And as shown in FIG. 7, these illuminating devices 10 and the display part 6 are stored in the case 21 which provided the operation part 21a with the power supply and display control part which are not shown in figure. With such a configuration, when the external light is sufficiently bright, the operation unit 21a can be operated to turn off the lighting device 10 to view the display unit 6, and when the external light is not sufficient and the light is dark, the operation unit 21a is operated. Then, the illumination device 10 can be turned on to view the display unit 6. Without these operations, the brightness of the external light may be detected and the lighting device 10 may be turned on when it is dark, and the lighting device 10 may be turned off when it is bright. In any case, when the lighting device 10 is turned on, uniform and sufficient luminance can be obtained, so that the visibility of the display unit 6 is ensured. When the lighting device 10 is turned off, the visibility of the display unit 6 is ensured because the lighting device 10 is transparent.

In the present embodiment, the display unit 6 employs an electrophoretic method. As shown in FIG. 8, a plurality of microcapsules 61 as electrophoretic elements are arranged between an element substrate 62 and a counter substrate 63. A large number of pixels configured as described above are provided on the entire display region 60 in a planar manner. The display area 60 is, for example, a portion excluding the inside of about 5 mm from the edge of the light guide plate 11 and a portion not covered with the case 21.
The microcapsule 61 has a particle diameter of about 50 μm, for example, and is a spherical body in which a dispersion medium such as oil, a large number of white particles 64 and black particles 65 are enclosed.

  The white particles 64 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white, and antimony trioxide, and are used, for example, by being negatively charged. The black particles 65 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used, for example, positively charged. These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compound charge control agents, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added. Further, instead of the black particles 65 and the white particles 64, for example, pigments such as red, green, and blue may be used. According to such a configuration, red, green, blue, and the like can be displayed.

8A and 8B are explanatory diagrams of the operation of the electrophoretic element. FIG. 8A shows a case where the pixel is displayed in white, and FIG. 8B shows a case where the pixel is displayed in black. In the case of white display, the transparent electrode 62 on the illumination device 10 side is held at a relatively high potential and the electrode 63 is held at a relatively low potential. Thereby, the negatively charged white particles 64 are attracted to the electrode 64, while the positively charged black particles 65 are attracted to the electrode 63. As a result, when this pixel is viewed from the electrode 62 side which is the display surface side, a white (W) point is recognized. In the case of black display shown in FIG. 8B, the electrode 62 is held at a relatively low potential and the electrode 63 is held at a relatively high potential. Thereby, the positively charged black particles 65 are attracted to the electrode 63, while the negatively charged white particles 64 are attracted to the electrode 63. As a result, when this pixel is viewed from the electrode 63 side, a black (B) point is recognized.
FIG. 8 is an operation explanatory diagram when black particles are positively charged and white particles are negatively charged. However, if necessary, black particles may be negatively charged and white particles may be positively charged. Good. In this case, when a potential is supplied in the same manner as described above, a display in which white display and black display are reversed can be obtained.

  In the electrophoretic display device 20 configured as described above, outside light is incident from the surface 11b side in a bright place such as in the daytime or indoors, and after passing through the electrophoretic element such as the microcapsule 61, the reflecting plate is used. The light is reflected by the electrode 63 that is also used, and is again transmitted through the electrophoretic element and emitted. Thereby, the monochrome display by an electrophoretic element is visually recognized.

  In the display device of the present invention, for example, the display area 60 has a substantially rectangular shape, and the diagonal length is in the range of 5.1 cm (2 inches) to 36.4 cm (A4 size). Even on a large screen such as an A4 size, the entire display area 60 can be illuminated with uniform brightness, and a reduction in display visibility can be minimized.

  In the present embodiment, an electrophoretic display unit is used as the display unit 6, but a display unit using cholesteric liquid crystal may be used.

Hereinafter, a third embodiment of a lighting device and a display device according to the present invention will be described with reference to the drawings.
FIG. 9 is a schematic side cross-sectional view showing the display device 30 in the present embodiment, and reference numeral 7 denotes an object to be illuminated. In the present embodiment, components corresponding to the configurations shown in the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the display unit 7 as a display medium is a reflective liquid crystal display device, and the display area 70 is an area corresponding to the display area 60 shown in FIGS. The liquid crystal is arranged between the electrodes.
As shown in FIG. 9, the light guide plate 11 is disposed adjacent to the front surface of the display area 70 of the display unit 7. A reflective plate 71 is disposed on the back surface of the display unit 7 to constitute a reflective liquid crystal display device. The light guide plate 11 irradiates the display unit 7 and can transmit the light reflected by the reflection plate 71 and passing through the liquid crystal with little scattering. For this reason, when the light source 14 is turned off in a place where the external light is sufficiently irradiated, since the external light is applied instead of the light from the light source 14, the visibility is prevented from being lowered and the display quality is affected. Can be minimized. Further, when the light source 14 is turned on in a dark place where the outside light is not sufficient, the light guide plate 11 uniformly illuminates the entire display area 70, and the light reflected by the reflection plate 71 and passing through the liquid crystal is turned off as described above. As with time, it can be transmitted with almost no scattering. For this reason, high visibility can be obtained.

  In the transmissive liquid crystal display device, since the backlight is arranged behind the liquid crystal, the light from the backlight is transmitted only once through the liquid crystal to generate contrast in bright and dark areas. In the reflection type liquid crystal display device as described above, the illumination device 10 as a front light is arranged in front of the display unit 7, so that the light from the illumination device 10 is reflected by the reflection plate 71 after passing through the liquid crystal once. Therefore, the contrast is increased and high visibility can be obtained. Thereby, the thin surface illumination suitable for display media, such as a display and a display body using external light, can be provided.

In addition, there is a lighting device that can be used alone for reading when reading a paper book as a display medium in a dark environment where there is insufficient external light, or for lighting outdoor maps as a display medium. It is convenient if there is. For example, as illustrated in FIG. 10, such a lighting device 40 stores the light source 14 and a power source (not illustrated) in a case 41 having an operation unit 41 a with most of the lighting device 40 exposed (projected). It can be configured. When using the lighting device 40, at least a part of a display area which is a printing surface of an object to be illuminated (display medium) such as a paper book is covered with the light guide 11. When the power supply to the light source 14 is turned on in this state, the light from the light source 14 is reflected by the dot-like reflective recesses 12 dispersed throughout the light guide plate 11, and the display medium on the back surface 11c side is uniformly illuminated. The As a result, it is possible to visually recognize characters, illustrations, and the like on the display area.
As described above, according to the embodiments of the present invention, it is possible to provide a lighting device that is thin, has high illuminance uniformity, uses less light sources, saves power, and has a built-in display device with a simple configuration. it can.

Hereinafter, 2nd Embodiment of the illuminating device and display apparatus which concern on this invention is described based on drawing.
In the present embodiment, components corresponding to the configurations shown in the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted. The display device 70 in the present embodiment is different from the embodiment shown in FIGS. 6 and 7 in that the illumination device 71 (10) is detachably provided, and FIG. FIG. 12 is a schematic side sectional view showing the display device 70 from which the illumination device 71 is detached in the embodiment, and FIG. 12 is a schematic side sectional view showing the display device 70 to which the illumination device 71 in this embodiment is attached.

According to the display device 70 of the present embodiment, the plurality of locking portions 18 are provided at the four corner edges of the lighting device 10, and the locking portions 18 are locked to the display device 72 to be the lighting device 10. Is installed.
The locking portion 18 includes a protruding portion 18a that protrudes in the t direction from the back surface 11c of the light guide plate 11, and a flexible protruding portion 18b that can be locked to the case 21 provided inward at the tip thereof. have. The locking portion 18 can be integrated with the light guide plate 11.
As shown in FIG. 13, the position where the locking portion 18 is provided may be any position as long as it is outside the display area 60, and is not limited to the four illustrated positions. Further, the locking portion itself is not limited to the shape shown in the drawing, and a configuration in which a rotating switching fixing portion or the like is provided in addition to a flexible configuration is also possible.

  Furthermore, the lighting device of the present invention has various uses. Illustrating this, lighting of mobile devices such as mobile phones, small information devices, watches, compact lighting for reading used on book pages, in-plane reading lighting, outdoor map lighting, loupe lighting, Lighting used for small household items such as photo frame lighting and frame lighting.

6 ... Illuminated body (display device, display medium), 7 ... Illuminated body (display device, display medium), 10 ... Illuminating device, 11 ... Light guide plate, 11a ... End face, 11b ... Non-opposing surface (front surface), 11c ... opposing face (back face), 12a ... reflective face, 60, 70 ... illuminated area (display area), 12 ... dot-like reflective recess, 12a ... reflective face, 14 ... light source

Claims (10)

A lighting device comprising a light guide plate capable of covering at least a part of a plate-shaped display medium, and a light source provided on an end surface of the light guide plate,
The light guide plate is provided with a dot-like reflective recess having a reflective surface inclined to the light source side with respect to the non-facing surface on a non-facing surface opposite to the side facing the display medium. The light transmitted by the optical plate is reflected by the reflecting surface of the dot-like reflecting recess to illuminate the display medium,
Set the aperture ratio of the dot-shaped reflective recess to 0.5 to 5% ,
The planar shape of the dot-like reflective recess is a substantially rectangular shape, and its aspect ratio is 1: 1.
Surface roughness of the reflecting surface of the dot-shaped reflector recess, the lighting device according to claim der Rukoto below 1 [mu] m. The reflecting surface of the dot-shaped reflecting concave lighting device according to claim 1, with respect to the non-facing surface of the light guide plate, and being inclined at 80 degrees or less than 30 degrees. The lighting device according to claim 1 or 2 opening size of the dot-shaped reflective concave portion is characterized in that it is set to 1 m to 1 mm. The lighting device according to any one of claims 1 to 3 , wherein a pitch of the dot-like reflective recesses is set to 1 µm to 1 mm. The illumination device according to any one of claims 1 to 4 , wherein the display medium is a liquid crystal display device or an electrophoretic display device. A display device comprising: a plate-like display unit; a light guide plate capable of covering at least a part of the display unit; and a light source provided on an end surface of the light guide plate,
The light guide plate is provided with a dot-like reflective recess having a reflective surface inclined to the light source side with respect to the non-facing surface on a non-facing surface opposite to the side facing the display medium. The light transmitted by the light plate is reflected by the reflecting surface of the dot-like reflecting recess to illuminate the display unit,
Set the aperture ratio of the dot-shaped reflective recess to 0.5 to 5% ,
The planar shape of the dot-like reflective recess is a substantially rectangular shape, and its aspect ratio is 1: 1.
Surface roughness of the reflecting surface of the dot-shaped reflective concave portion is a display device according to claim der Rukoto below 1 [mu] m. The display device according to claim 6 , wherein a reflective surface of the dot-like reflective recess is inclined at 30 degrees or more and 80 degrees or less with respect to a non-facing surface of the light guide plate. 8. The display device according to claim 6, wherein an opening size of the dot-like reflective recess is set to 1 μm to 1 mm. The display device according to any one of claims 6 to 8 , wherein a pitch of the dot-like reflective recesses is set to 1 µm to 1 mm. Wherein the display unit, a liquid crystal display device or the display device according to any one of claims 6-9, characterized in that is composed of a display device of an electrophoretic system.

Images