JP2016080737A - Lighting device, and liquid crystal display device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of preventing luminescence unevenness, while being miniaturized.SOLUTION: A lighting device includes: a nearly rectangular light guide plate (10) arranged in such a manner that an incident surface incident with light and an emission surface for irradiating guided light are arranged to be nearly orthogonal to each other; a point light source (20) arranged to face the incident surface; and a finder internal liquid crystal display device (30) for displaying nearly rectangular imaging information. The emission surface is treated with mat processing having a light diffusion effect. The surface opposite to the emission surface is arranged with a reflection surface treated with a Fresnel shape. The side face of the finder internal liquid crystal display device is arranged to face the emission surface of the light guide plate, and a portion inside the emission surface is provided with a protrusion protruded further than the periphery. The protrusion, when viewed from the normal line of the emission surface, has a nearly rectangular shape. The protrusion is arranged within the range of the display area of the finder internal liquid crystal display device.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an illuminating device including a light guide plate, and more particularly to an illuminating device in which a point light source is disposed on a side surface of the light guide plate and a liquid crystal display device including the same.

  In recent years, digital cameras that convert an optical image of a subject into an electrical image signal to capture an image, particularly digital single-lens reflex cameras with interchangeable lenses, have rapidly become widespread. A liquid crystal display device is used for in-viewfinder display that superimposes and displays shooting information such as a distance measurement frame and a shooting mode on a camera finder image. Since the liquid crystal panel is not self-luminous, an illumination device is required. Since the illumination device in the viewfinder is required to be thin, it is arranged on the side surface instead of the back surface of the liquid crystal panel. A light emitting diode (LED) suitable for miniaturization is employed as a light source of the lighting device.

  However, if the liquid crystal panel is directly illuminated by the LED, the vicinity of the LED becomes brighter than the surroundings, and uneven brightness occurs in the liquid crystal panel, degrading the display quality. Therefore, a configuration is adopted in which a light guide plate is disposed on the side surface of the liquid crystal panel, the exit surface of the light guide plate is matted, and the LED is illuminated from the side surface of the light guide plate. By doing so, it is possible to irradiate light with uniform brightness from the light guide plate, and to solve the brightness unevenness of the liquid crystal panel to some extent.

  However, when the LED light source is close to the liquid crystal panel display area, the luminance unevenness cannot be solved. As a countermeasure, a configuration is known in which a deflection structure is provided outside the effective light emitting area of the light guide plate, that is, outside the display area of the liquid crystal panel (see Patent Document 1). The deflection structure has a surface inclined with respect to the emission surface, and changes the light that has arrived from the inside of the light guide plate in a direction parallel to the emission surface and emits the light. Thereby, the uneven brightness of the liquid crystal panel is eliminated.

  On the other hand, as a further problem, a recess having a large area (a recess by an ejector pin) is generated on the mat surface of the light guide plate. Then, the direct light from the LED is refracted at the end face of the recess, and enters the display area of the liquid crystal panel as abnormal light. As a result, linear luminance unevenness due to abnormal light occurs in the liquid crystal panel, and display quality is impaired. As a solution to this problem, a configuration is known in which the end surface of the recess is disposed outside the display area of the liquid crystal panel. An illumination device having such a configuration is schematically shown in FIG.

  FIG. 7A is a schematic view of a conventional lighting device. The light guide plate 101 is provided with an exit surface 101a and an entrance surface 101c, and the exit surface 101a is matted with a light diffusion effect over the entire area. The LED 102 is disposed to face the incident surface 101 c of the light guide plate 101. The liquid crystal panel 103 is arranged so that the incident surface 103 b which is the side surface thereof faces the output surface 101 a of the light guide plate 101. The liquid crystal panel 103 is provided with a display area 103a to be illuminated. As shown in the figure, the exit surface 101 a of the light guide plate 101 has a recess 101 e formed by protruding ejector pins, and the end surface of the recess 101 e is arranged outside the display area 103 a of the liquid crystal panel 103.

  FIG. 7B is an enlarged view of the vicinity of the end face of the concave portion 101e of the light guide plate 101 surrounded by the dotted frame A in FIG. In addition, the thick line arrow in a figure represents the direct light from LED102, and if it injects into the display area 103a of the liquid crystal panel 103, it will lead to generation | occurrence | production of brightness irregularity as abnormal light. As shown in the figure, the direct light from the LED 102 is refracted at the end face of the recess 101e. However, since the distance from the end surface of the recess 101e to the display area 103a is sufficiently secured, the refracted light attenuates (the dotted arrow in the figure represents the attenuated light), and abnormal light is present in the display area of the liquid crystal panel. Will not be incident. Thereby, the linear luminance unevenness is eliminated.

JP 2012-134124 A

  However, in the above-described conventional technology, the linear luminance unevenness cannot be eliminated, and when the intensity of the LED light is increased, the luminance unevenness becomes visible. In addition, the light guide plate must be made larger than the display area of the liquid crystal panel, and the lighting device cannot be reduced in size.

  Accordingly, an object of the present invention is to provide an illumination device that can prevent luminance unevenness while being downsized.

  In order to achieve the above object, the illumination device of the present invention includes a substantially rectangular light guide plate arranged so that an incident surface on which light is incident and an output surface on which light is guided are substantially orthogonal, A point light source disposed opposite to the incident surface, and a liquid crystal display device in a viewfinder for displaying substantially rectangular shooting information, and the exit surface is subjected to a matting process having a light diffusion effect, and the exit surface A reflective surface with a Fresnel shape is disposed on the opposite surface, and the side surface of the in-viewfinder liquid crystal display device is disposed to face the light exit surface of the light guide plate. Protrusions that protrude from the periphery are provided on the part, and the protrusions have a substantially rectangular shape when viewed from the normal direction of the exit surface, and the protrusions are provided in the display area of the liquid crystal display device in the viewfinder. It is arranged within the range.

  ADVANTAGE OF THE INVENTION According to this invention, the illuminating device which enabled it to prevent a brightness nonuniformity, reducing in size can be provided.

It is the schematic which shows the function structure of the digital camera which concerns on this embodiment. It is a perspective view of the display unit in the viewfinder of the digital camera according to the present embodiment. It is the schematic of the display unit in a finder of the digital camera which concerns on this embodiment. It is the schematic which looked at the light-guide plate which concerns on this embodiment from the normal line direction of the output surface. It is an enlarged view of the end surface of the convex part of the light-guide plate which concerns on this embodiment. It is the schematic of the convex part of the output surface of the light-guide plate which is a modification which concerns on this embodiment. It is the schematic of the conventional illuminating device.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail based on attached drawing.
[Example 1]
FIG. 1 is a schematic diagram illustrating a functional configuration of a digital camera 200 according to the present embodiment. The taking lens unit 201 is connected to the digital camera 200. The main mirror 202 moves between a position where the subject image can be observed by the finder (mirror down position) and a position where the subject image is retracted (mirror up position). When in the mirror down position, the main mirror 202 guides the photographic light beam passing through the photographic lens 201 to the pentaprism 203 while being held at an angle of 45 degrees with respect to the photographic optical axis shown in FIG. This part is transmitted and guided to the sub mirror 204.

  The sub mirror 204 guides the photographing light beam transmitted through the main mirror 202 to the focus detection sensor unit 205. On the other hand, at the mirror-up position, not only the main mirror 202 but also the sub-mirror 204 moves to a position where the imaging light beam is retracted, and a subject image is formed on the image sensor 207 described later. The focus detection sensor unit 205 performs phase difference type focus detection. Based on the signal output from the focus detection sensor unit 205, the focus lens in the interchangeable lens 201 is moved to the focus position, and the imaging light beam is focused on the image sensor 207.

  The pentaprism 203 converts and reflects the photographing light beam reflected by the main mirror 202 into an erect image. Thus, the photographer can observe the subject image from the viewfinder eyepiece window 206 through the viewfinder optical system. The in-finder display unit 210 is a block in which components including a liquid crystal panel 30 such as a PN liquid crystal and a lighting device that illuminates the liquid crystal panel 30 are unitized. The in-finder display unit 210 displays the shooting information of the camera such as the distance measurement frame and the shooting mode so as to overlap the subject image.

  The imaging element 207 is an imaging device such as a CMOS sensor or a CCD, for example, and photoelectrically converts an optical image of the formed subject. An optical low-pass filter 208 is disposed in front of the image sensor 207.

  FIG. 2 is a perspective view of the in-finder display unit 210 of the digital camera according to the present embodiment. FIG. 3 is a schematic view of the in-finder display unit 210 of the digital camera according to the present embodiment. An LED 20 is connected to a flexible printed circuit board (not shown) and emits light when a voltage is applied through the flexible printed circuit board. The LED 20 is disposed to face the incident surface 12 of the light guide plate 10. In addition, LED20 is a point light source as described in a claim. The light guide plate 10 is substantially rectangular, and is provided with an exit surface 11 in the longitudinal direction and an entrance surface 12 in the lateral direction, and both are orthogonal to each other. The exit surface 11 is matted with a light diffusion effect over the entire area.

  On the other hand, a reflection surface 13 having a Fresnel shape is provided on the opposite side of the emission surface 11. Reference numeral 30 denotes a substantially rectangular liquid crystal panel, which is provided with a display area 32, and displays shooting information of the camera such as a distance measurement frame and a shooting mode in the display area. The liquid crystal panel 30 is arranged such that the incident surface 31 that is the side surface thereof faces the light emitting surface 11 of the light guide plate 10. The liquid crystal panel 30 is the in-finder liquid crystal display device described in the claims. Reference numeral 40 denotes a holding member that holds the light guide plate 10, the LED 20, and the liquid crystal panel 30 at desired positions.

  The light of the LED 20 enters from the incident surface 12 of the light guide plate 10 and is reflected by the reflecting surface 13 so that the amount of light is uniform in the direction of the liquid crystal panel 30. Then, when the light of the LED 20 is emitted from the emission surface 11, the light is diffused by the mat, and more uniform surface emission is generated. The light is incident from the incident surface 31 of the liquid crystal panel 30, and uniformly illuminates the display region 32.

  Here, the exit surface 11 of the light guide plate 10 will be described in detail. As described above, when the light emitting plate 11 and the reflecting surface 13 are provided on the light guide plate 10, it is necessary to project the ejector pins on the light emitting surface 11 when forming the light guide plate 10. As shown in FIG. 3, the region where the ejector pin protrudes is a convex portion protruding from the surrounding light exit surface 11. Let this convex part be 11a. By controlling the protrusion amount of the ejector pin, the protrusion amount of the protrusion 11a can be managed. In addition, the mat | matte process is given to the convex part 11a similarly to the surrounding output surface. FIG. 4 is a schematic view of the light guide plate 10 as viewed from the normal direction of the emission surface 11.

  As shown in the figure, the convex portion 11 a has a substantially rectangular shape when viewed from the normal direction of the emission surface 11. Protruding a wide area to some extent can prevent warping of molding and the like, leading to an improvement in the quality of the light guide plate 10. Further, when viewed from the normal direction of the exit surface 11 of the light guide plate 10, the convex portion 11 a is disposed within the display area 32 of the liquid crystal panel 30. By doing so, it is possible to make the entire emission surface 11 including the convex portion 11 a smaller than the incident surface 31 of the liquid crystal panel 30. Furthermore, the length of the light guide plate 10 in the longitudinal direction can be reduced with respect to the incident surface 31 of the liquid crystal panel 30. Thereby, the size of the entire lighting device can be reduced.

  Next, the arrangement of the end surface 11b and the end surface 11d of the convex portion 11a of the light guide plate 10 will be described. FIG. 5 is an enlarged view of the end surface of the convex portion 11a. Fig.5 (a) is an enlarged view of the end surface 11b of the convex part 11a at the side close | similar to LED20 (enlarged view of the dotted-line round frame A in FIG. 3). FIG. 5B is an enlarged view of the end surface 11d of the convex portion 11a on the side far from the LED 20 (enlarged view of a dotted-line round frame B in FIG. 3). In addition, the thick line arrow in a figure represents the direct light from LED20, and if it injects into the display area 32 of the liquid crystal panel 30, it will lead to generation | occurrence | production of brightness irregularity as abnormal light. Although not shown, normal light is light that is reflected by the reflecting surface 13 from the LED 20 and travels toward the liquid crystal panel 30.

  As shown in FIG. 5A, the end surface 11b of the convex portion 11a on the side close to the LED 20 is disposed at a position where the direct light from the LED 20 is totally reflected by the emission surface 11c before the end surface 11b and does not enter the end surface 11b. ing. The end face 11b cannot be subjected to mat processing in terms of molding. This is because if the mat treatment is performed, the light guide plate 10 is cast, warping or the like occurs in the light guide plate 10, and the quality is deteriorated. Further, the strength of the mold itself is significantly impaired, and the maintenance cycle of the mold is shortened. If the LED direct light is incident on the end surface 11b that is not matted, strong light is directly incident on the liquid crystal panel 30 without being diffused, and luminance unevenness occurs.

  However, with the above configuration, direct light from the LED 20 does not pass through the end surface 11b and enter the display region 32 of the liquid crystal panel 30, and linear luminance unevenness can be prevented.

  As shown in FIG. 5B, the end surface 11 d of the convex portion 11 a far from the LED 20 is a position where the direct light from the LED 20 is emitted from the end surface 11 d and the direct light is totally reflected by the incident surface 31 of the liquid crystal panel 30. Is arranged. As described above, since the end surface 11d cannot be matted for molding, the LED direct light transmitted through the end surface 11d is not diffused and is emitted toward the liquid crystal panel 30 as strong light. However, with the above configuration, direct light from the LED 20 does not enter the display region 32 of the liquid crystal panel 30, and linear luminance unevenness can be prevented.

  With the above configuration, it is possible to make the size of the light guide plate 10 smaller than the side length of the liquid crystal panel 30 while preventing unevenness in the brightness of the display area 32 of the liquid crystal panel 30 due to direct light from the LEDs 20. The lighting device can be downsized.

  Below, the modification of the convex part of the output surface of a light-guide plate is shown. FIG. 6 is a schematic view of a convex portion on the exit surface of the light guide plate. As shown in FIG. 6A, the region 51a where the ejector pin protrudes in the exit surface 51 of the light guide plate 50 is inclined with respect to the exit surface 51, and the side closer to the LED 20 has a convex portion. The side far from the LED 20 has a recess. As described above, the convex end surface 51b is disposed at a position where the direct light from the LED 20 is totally reflected by the emission surface 51c in front of the end surface 51b and does not enter the end surface 51b. On the other hand, since the light transmitted through the matted region 51a reaches the concave end surface 51d, luminance unevenness of the liquid crystal panel 30 does not occur.

  Therefore, the recessed end surface 51d may be disposed at a position necessary for molding. Even with the configuration described above, the size of the light guide plate 50 can be made smaller than the length of the side surface of the liquid crystal panel 30 while preventing luminance unevenness in the display region 32 of the liquid crystal panel 30 due to direct light from the LEDs 20. As a result, the lighting device can be downsized.

  Further, as shown in FIG. 6B, the convex portion 61 a in the region where the ejector pin protrudes in the emission surface 61 of the light guide plate 60 has an end surface 61 b near the LED 20 having a gradient with respect to the emission surface 61. It has a shape. This gradient may be set to an angle at which direct light from the LED 20 (thick arrow in the figure) does not hit the end face 61b. Therefore, direct light from the LED 20 does not pass through the end face 61b and enter the display area 32 of the liquid crystal panel 30, and linear luminance unevenness can be prevented. On the other hand, the end surface 61c of the convex portion 61a on the side far from the LED 20 is arranged at a position where the direct light from the LED 20 is emitted from the end surface 61c and totally reflected by the incident surface 31 of the liquid crystal panel 30 as described above. Has been.

  Even if comprised as mentioned above, it is possible to make the size of the light guide plate 60 smaller than the side length of the liquid crystal panel 30 while preventing the luminance unevenness of the display area 32 of the liquid crystal panel 30 due to the direct light from the LED 20. As a result, the lighting device can be downsized.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 10 Light guide plate, 11 Output surface, 11a Convex part, 20 LED, 30 Liquid crystal panel

Claims (4)

A rectangular light guide plate (10) disposed so that an incident surface for incident light and an output surface for irradiating guided light are orthogonal to each other;
A point light source (20) disposed opposite the incident surface;
A liquid crystal display device (30) in the viewfinder for displaying rectangular shooting information,
The exit surface is subjected to a matte treatment having a light diffusing effect, and a reflective surface having a Fresnel shape is disposed on the surface opposite to the exit surface,
The liquid crystal display device in the finder is arranged with its side surface facing the emission surface of the light guide plate,
Providing a convex part protruding from the periphery in a part in the emission surface,
The convex portion has a rectangular shape when viewed from the normal direction of the exit surface,
The illuminating device, wherein the convex portion is disposed within a display area of the in-viewfinder liquid crystal display device. The convex end surface on the side close to the incident surface of the light guide plate is arranged so that the direct light of the point light source is totally reflected by the exit surface near the convex end surface on the side close to the incident surface of the light guide plate. The lighting device according to claim 1. The direct light of the point light source emitted from the end surface of the convex portion on the side far from the incident surface of the light guide plate is totally reflected on the side surface of the liquid crystal display device in the viewfinder, and is on the side far from the incident surface of the light guide plate. The lighting device according to claim 1, wherein the end face of the convex portion is arranged. 4. The lighting device according to claim 1, wherein a length of the light guide plate in a longitudinal direction is shorter than a side surface of the in-viewfinder liquid crystal display device.