JP2007033633A - Video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video display device by which a high-definition video image is obtained at low cost, with less crosstalk and less illumination irregularity. <P>SOLUTION: The video display device is equipped with an illumination means for emitting first, second and third light fluxes at least in three different directions, respectively by time sharing, a transmission display element capable of displaying a first video image using the first light flux as illumination light, a second video image using the second light flux as illumination light and a third video image using the third light flux as illumination light by time sharing, the illumination means is equipped with a first light source 20 which emits the first light flux, a second light source 25 which emits the second light flux, a third light source 29 which emits the third light flux, a first light guide plate 21 which emits the first light flux emitted from the first light source 20 only in the direction of a first observer, a second light guide plate 22 which emits the second light flux emitted from the second light source 25 only in the direction of a second observer and a third light guide plate 23 which emits the third light flux emitted from the third light source 29 only in the direction of a third observer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a video display device.

  2. Description of the Related Art Conventionally, there has been known an image display device that has one display surface and can observe an image corresponding to each viewing direction. For example, Japanese Patent No. 3072866 discloses a display device in which images can be observed from two directions using matrix illumination and a lenticular lens.

  Japanese Patent Laying-Open No. 2005-77437 discloses an image display apparatus in which one lenticular lens is associated with three light sources so that an image can be observed from three directions.

  Japanese Patent No. 3585781 discloses a first and second wedge-shaped light guides, and a first wedge light guide that is disposed on the first and second wedge light guides. A prism film that converts the emitted light from the first light source and the second light source into angles corresponding to the first and second parallaxes, a transmissive display panel disposed on the prism film, and first and second There is disclosed a stereoscopic display device including a synchronous driving unit that displays a parallax image on a display panel.

Japanese Patent No. 3072866 JP-A-2005-77437

  In Japanese Patent No. 3072866, since observation from the front is not supported, for example, when considering application to an in-vehicle image display device, images can be observed from the driver's seat and passenger seat, Inconveniences such as seat passengers being unable to observe images occur. In addition, in an optical system using a lenticular lens, if the left and right images are separated at a large angle, the focal length must be reduced, the curvature becomes very large, and the aberration increases with the result. In particular, there is a problem that the influence of crosstalk becomes large.

  Japanese Patent Application Laid-Open No. 2005-77437 also allows front-view observation, but uses a lenticular lens, and thus has the same problem as described above.

  In Japanese Patent No. 3585781, a prism film is used instead of a lenticular lens. Since the prism film has many edge portions, scattered light and unnecessary stray light are generated, causing crosstalk. Further, since the prism film is usually designed to change the directivity of light in a specific direction, it is difficult to control incident light in three directions.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a video display device and an in-vehicle video display device that can obtain a high-quality video with little crosstalk. is there.

  Another object of the present invention is to provide a video display device and a vehicle-mounted video display device that can observe videos from multiple directions such as right, left, and front.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a video display device having a single display screen capable of displaying video corresponding to each of a plurality of observers, and at least 3 in a time division manner. Illumination means for emitting first, second, and third light fluxes in two different directions, a first image that uses the first light flux emitted from the illumination means as illumination light, and the second light flux, respectively. A transmissive display element capable of displaying in a time-division manner a second image that uses illumination light as a second image and a third image that uses the third light flux as illumination light. A first light source that emits one light beam, a second light source that emits the second light beam, a third light source that emits the third light beam, and a first light source emitted from the first light source. A first light guide plate that emits one light beam only in the direction of the first observer, and the second light source. A second light guide plate that emits the second light flux emitted only in the direction of the second observer, and a third light flux emitted from the third light source only in the direction of the third observer. A third light guide plate. Thus, by using a light guide plate having a three-plate structure, illumination in the third direction as well as the left and right directions is possible.

  According to a second aspect of the present invention, in the first aspect, at least one of the first, second, and third light beams has an emission direction with respect to the display surface of the transmissive display element. This is the central illumination light flux that is normal. This also enables illumination in the front direction.

  According to a third aspect of the present invention, in the second aspect, the illumination range of the central illumination light beam is different from the illumination range of other light beams. For example, considering the in-vehicle environment, the driver and passenger seats need a wide observation range close to the display element, but in the observation from the center of the rear seat, which is far away, a narrow observation range is sufficient. In this way, by making the illumination range of the central illumination light beam different from the illumination range of other light beams, it is possible to provide an image that is easy to see for any observer.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, at least one of the first and second light guide plates and the second and third light guide plates. A diffusion plate is arranged. According to such a configuration, it is possible to independently control the spread of the three light beams.

According to a fifth aspect of the present invention, in the fourth aspect, the first light guide plate emits the central illumination light beam. This is a specific embodiment of the third aspect, in which the luminous flux in the normal direction does not pass through the diffuser plate and therefore has a narrow illumination range, and the luminous flux in the other direction passes through the diffuser plate, and thus has a wide illumination range. It becomes.

  According to a sixth aspect of the present invention, in the third aspect, a field selection element is disposed in front of the first, second, and third light guide plates, and the field selection element is incident in a normal direction. The transmitted light is transmitted as it is, and light incident at an angle is diffused and transmitted. This is a specific embodiment of the third aspect, and the effect is the same as that of the fifth aspect.

  According to a seventh aspect of the present invention, in the first aspect, the first, second, and third light sources sequentially emit light in a time-sharing manner, and the transmissive display element includes the first, second, The third video is sequentially displayed in a time division manner. According to such a configuration, it is possible to provide different images in three directions.

  According to an eighth aspect of the present invention, in the first aspect, at least one of the first, second, and third light sources has the same lighting timing as the other light sources. According to such a configuration, the same image can be observed in two of the three observation areas.

  According to a ninth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source and the first light source. A first light guide plate that emits the emitted first light flux only in the direction of the first observer, a second light source, and a second light flux emitted from the second light source for the second observation. At least a second light guide plate that emits only in the direction of the person, illuminating means that emits the first and second light fluxes in at least two different directions in a time-sharing manner, and the light emitted from the illuminating means A transmissive display element capable of displaying, in a time division manner, a first image using the first light flux as illumination light and a second image using the second light flux as illumination light, the illumination means, and the transmission And an expansion device for diffusing the first and second light fluxes from the illumination means. It includes functions and, first, a diffuse transmission device and a transmission function of transmitting the second beam, and a switching means for switching between the diffusion function and the transmission function of the diffuse transmission element. In the case of illumination with directivity in different directions, it is suitable for observing different images depending on the direction, but if you want to observe the same image from any direction, the brightness at the boundary of each directivity The video is difficult to see due to its low level. As in the ninth aspect, by enabling switching to omnidirectional illumination, it is possible to provide an image that can be easily observed in both scenes.

  According to a tenth aspect of the present invention, in the ninth aspect, the diffuse transmission element is made of a nematic liquid crystal, and the switching by the switching means is performed based on ON / OFF of a voltage to be applied.

  According to an eleventh aspect of the present invention, in the ninth aspect, when the diffuse transmission element functions as a diffusion element, the first light flux and the second light flux are emitted simultaneously. In the case of illumination with directivity in different directions, it is suitable for observing different images depending on the direction, but if you want to observe the same image from any direction, the brightness at the boundary of each directivity The video is difficult to see due to its low level. As in the eleventh aspect, by enabling switching to omnidirectional illumination, it is possible to provide an image that can be easily observed in both scenes.

  According to a twelfth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source, and the first light source. A first light guide plate that emits the emitted first light flux only in the direction of the first observer, a second light source, and a second light flux emitted from the second light source for the second observation. At least a second light guide plate that emits only in the direction of the person, and a first illumination unit that emits the first and second light fluxes in at least two different directions in a time-sharing manner, and the first illumination And a second illuminating unit that emits a light beam that is transmitted through the first illuminating unit and has no directivity. According to such a configuration, the omnidirectional illumination is obtained when the diffusion backlight is turned on, and an image that is easy to view from the front direction as well as the left-right direction can be provided.

  According to a thirteenth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source, and the first light source. A first light guide plate that emits the emitted first light flux only in the direction of the first observer, a second light source, and a second light flux emitted from the second light source for the second observation. At least a second light guide plate that emits only in the direction of the person, illuminating means that emits the first and second light fluxes in at least two different directions in a time-sharing manner, and the light emitted from the illuminating means A transmissive display element capable of displaying, in a time division manner, a first image using the first light flux as illumination light and a second image using the second light flux as illumination light, the illumination means, and the transmission A first light beam from the first light guide plate, and the second In the second light flux from the light guide plate comprises a a field selection device capable of varying the degree of diffusion. According to such a configuration, the light of the first light flux can be largely diffused by the visual field selection element, and the light of the second light flux can be made small diffusion. TV images and the like can be provided to the passenger seat and the rear seat without disturbing the driver's attention.

According to a fourteenth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying images corresponding to a plurality of observers, the first light source, the first illumination lens, and the like. A first light guide plate that emits a first light beam incident at a predetermined NA by a combination of the first light source and the first illumination lens only in the direction of the first observer. The second luminous flux incident at an NA different from the predetermined NA by a combination of the illumination means, the second light source, the second illumination lens, and the second light source and the second illumination lens. A second illuminating unit including a second light guide plate that emits only in the direction of the second observer, and a first illuminant that uses the first luminous flux emitted from the first illuminating unit as illumination light. An image, and a second image using the second light flux emitted from the second illumination means as illumination light; When comprising a transmissive type display device capable of displaying, for a split. According to such a configuration, the NA of the light incident on the end surface of the light guide plate is different, so that the size of the viewing angle of the light emitted from each light guide plate is different, and the viewing angle suitable for each observation environment is set. It is possible to set.

  According to a fifteenth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source, and a slope having a predetermined shape. A first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the predetermined shape is different At least a second light guide plate that emits the second light beam emitted from the second light source only in the direction of the second observer. Illuminating means for emitting the first luminous flux in at least two different directions in a time division manner, a first image using the first luminous flux emitted from the illuminating means as illumination light, and the second luminous flux as illumination light And a transmissive display element capable of displaying the second video in a time-sharing manner. According to such a structure, the magnitude | size of the viewing angle of the light which each light guide plate injects can differ by making the shape of the slope part of two light guide plates into a different shape. It is possible to set the viewing angle according to each observation environment.

  According to a sixteenth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source, and the first light source. A first light guide plate that emits the emitted first light flux only in the direction of the first observer, a second light source, and a second light flux emitted from the second light source for the second observation. At least a second light guide plate that emits only in the direction of the person, illuminating means that emits the first and second light fluxes in at least two different directions in a time-sharing manner, and the light emitted from the illuminating means A transmissive display element capable of displaying, in a time-sharing manner, a first image using a first light flux as illumination light and a second image using the second light flux as illumination light, The light guide plate and the second light guide plate can be replaced with other light guide plates having different emission angles. According to such a configuration, it is possible to set a light emission direction in accordance with a place where the display device is arranged, because the light guide plates can be exchanged with different light emission angles.

  According to a seventeenth aspect of the present invention, there is provided an image display device having a single display screen capable of displaying an image corresponding to each of a plurality of observers, the first light source, and the first light source. A first light guide plate that emits the emitted first light flux only in the direction of the first observer, a second light source, and a second light flux emitted from the second light source for the second observation. At least a second light guide plate that emits only in the direction of the person, illuminating means that emits the first and second light fluxes in at least two different directions in a time-sharing manner, and the light emitted from the illuminating means A transmissive display element capable of displaying, in a time division manner, a first image using the first light flux as illumination light and a second image using the second light flux as illumination light, the illumination means, and the transmission And an emission angle of the first luminous flux and an emission angle of the second luminous flux. Includes a prism sheet that alter the angle, the. According to such a configuration, since the prism sheet can be inserted, it is possible to set the illumination emission direction according to the place where the display device is arranged.

  According to the present invention, a high-quality image can be obtained at low cost with little crosstalk and little illumination unevenness.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is directed to a video display device having a single display screen capable of displaying video corresponding to at least two observers.

(First embodiment)
The first embodiment is an embodiment in the case where an observer is arranged in two left and right directions. FIG. 1 is a diagram showing, in a horizontal section, an observable range of an image emitted from a display panel 24 that can display images corresponding to two observers. The display panel 24 emits the first image to the first observer existing in the first observer area 36 and the first image to the second observer existing in the second observer area 37. It is possible to emit a different second image. In this case, the central area 35 between the first observer area 36 and the second observer area 37 is a part where the image from the display panel 24 does not reach, and the image cannot be seen.

  FIG. 2 is a diagram showing a schematic configuration of an image display device capable of displaying images corresponding to two observers. The transmissive display element 24 and the light diffusing element 123 are sequentially arranged from the position of the observer. The first light guide plate 21 and the second light guide plate 22 are arranged. Thus, here, the first light guide plate 21 and the second light guide plate 22 are doubled. A first light source 20 is disposed adjacent to one end of the first light guide plate 21, and a second light source 25 is disposed adjacent to an end portion of the second light guide plate 22 opposite to the one end. That is, the first light source 20 and the second light source 25 are arranged at different positions on the left and right sides of the first light guide plate 21 and the second light guide plate 22.

  The light diffusing element 123 is disposed between the first light guide plate 21 and the transmissive display element 24 in order to reduce uneven illumination. Here, since the images are separated so as to have two directivities in the horizontal direction, if the diffusion in the horizontal direction is too strong, the two images may be mixed and appear as a double image. Therefore, it is preferable here to use a light diffusing element that suppresses horizontal diffusion rather than vertical diffusion. Specifically, it is desirable that the horizontal diffusion intensity distribution be 30 degrees or less at full width at half maximum.

  In addition, the first light guide plate 21 and the second light guide plate 22 have a configuration in which a special groove, an inclination, and a protrusion are provided in a transparent member, and light incident from the side surface is directed only in a certain direction having directivity. I am trying to inject. The first light source 20 and the second light source 25 may be anything as long as they are illuminated from one direction of the first light guide plate 21 and the second light guide plate 22, may be columnar light sources such as cold cathode tubes, and light sources such as LEDs are used. They may be used side by side.

  FIG. 3 is a horizontal cross-sectional view of the illuminating means of the video display device capable of displaying corresponding videos for two observers. Behind the light diffusing element 123, the first light guide plate 21 and the second light guide plate 22 are disposed so as to overlap each other. The first light source 20 is disposed adjacent to one end (the left end in the figure) of the first light guide plate 21, and the end of the second light guide plate 22 opposite to the one end (left end) of the first light guide plate 21 (in the figure). A second light source 25 is disposed adjacent to the right end). As described above, the positions where the first light source 20 and the second light source 25 are disposed are different between the first light guide plate 21 and the second light guide plate 22.

  In the following, the direction approaching the observer's position (upward in the figure) will be considered as the front. Light incident on the first light guide plate 21 from the first light source 20 is transmitted while being totally reflected in the first light guide plate 21, but a special surface treatment is applied to the surface of the first light guide plate 21 or a part thereof. Alternatively, by making the surface have a special shape, the light emitted from the first light guide plate 21 can be illuminated only in the direction of the first observer as the first video illumination 26. On the other hand, the light incident on the second light guide plate 22 from the second light source 25 is transmitted while being totally reflected in the second light guide plate 22, but a special surface treatment is applied to the surface of the second light guide plate 22 or a part thereof. Or by making the surface have a special shape, the light emitted from the second light guide plate 22 can be illuminated as the second video illumination 27 only in the direction of the second observer. The front-rear relationship in arrangement of the first light guide plate 21 and the second light guide plate 22 is arbitrary.

  FIG. 4 is a schematic diagram showing a specific cross-sectional structure of an image display device capable of displaying images corresponding to two observers. Here, similarly to the configuration of FIG. 3, the first light guide plate 21 and the second light guide plate 22 are disposed so as to overlap each other, and the positions at which the first light source 20 and the second light source 25 are disposed are set to the first light guide plate 21. And the second light guide plate 22 are different.

  Further, on the rear surfaces of the light guide plates 21 and 22, a plurality of slope portions 121-1 to 121-3 extend in a streak shape at a predetermined interval to form stepped portions. The first light guide plate 21 and the second light guide plate 22 have the same shape, but the left and right directions are different. A light absorbing member 28 for absorbing outside light and unnecessary light is disposed behind the second light guide plate 22.

  The light emitted from the first light source 20 enters the first light guide plate 21 and proceeds while repeating total reflection on the front and rear surfaces thereof, but the light totally reflected on the slope portions 121-1 to 121-3 is Since the light is reflected forward at a steeper angle than the light totally reflected on the horizontal surface of the first light guide plate 21, the total reflection condition is not satisfied on the front surface of the first light guide plate 21. Therefore, the light is illuminated as the first video illumination 26 in the first observation direction.

  On the other hand, the light emitted from the second light source 25 enters the second light guide plate 22 and travels while repeating total reflection on the front and rear surfaces thereof, but the light totally reflected on the slope portions 122-1 to 122-3. Is reflected forward at a steeper angle than the light totally reflected on the horizontal surface of the second light guide plate 22, the total reflection condition is not satisfied on the front surface of the first light guide plate 21. Therefore, the light is illuminated as the second video illumination 27 in the second observation direction.

  The second video illumination 27 derived from the second light source 25 passes through the first light guide plate 21 on the way, but is the same as when passing through the parallel flat plate in most parts other than the slope portions 121-1 to 121-3. In order to have an effect, the final emission angle does not change, and the change in angle when the second video illumination 27 is incident on the slope portions 121-1 to 121-3 of the first light guide plate 21 is the second observation. Since it changes in the direction toward the outer side of the position, that is, in the direction opposite to the first observation direction, it does not affect the crosstalk or the like.

  In the drawing, since it is schematically drawn, only three slopes are drawn on one side, but actually four or more are arranged at a predetermined pitch.

  FIG. 5 is a diagram for explaining an example of the drive timing of the video display device capable of displaying video corresponding to two observers. The first image (A) and the second image (B) are alternately displayed on the transmissive display element 24, and the first light source 20 that is a light source for the first light guide plate 21 and the second light guide plate 22. The images observed in the first observer area 36 and the second observer area 37 are determined according to the ON / OFF timing of the second light source 25 that is a light source for use. The first light source 20 is turned on only when the first video (A) is displayed. In this case, the first observer can observe only the first video. On the other hand, the second light source 25 is turned on only when the second image (B) is displayed. In this case, the second observer can observe only the second image. The images that can be observed are also switched by switching the timings of the first light source 20 and the second light source 25.

  Further, when the first light source 20 and the second light source 25 are turned on at the same timing, or when the first image and the second image are exactly the same image, the first observer and the second observer are The same image can be observed.

(Second Embodiment)
The second embodiment is an embodiment in the case where the observer is arranged in three directions, left, right, and center. In the first embodiment, only observation from the left and right directions is supported, and observation from the front direction is not considered. As a problem of this configuration, there is a drawback that the luminance in the front direction cannot be secured and the image is viewed as a dark image when viewed from the front. In addition, when used as an in-vehicle display monitor, it has been optimized between the driver's seat and the passenger's seat, and there is a problem that observation cannot be performed at the optimal position when the display monitor is shifted in position.

  As a means for solving such a problem, in the present embodiment, the dual light guide plate is used to provide the directivity in two directions. However, by adding one light guide plate for the front, it can be used in three directions. It is possible to respond.

  In addition, by providing means for switching the illumination in two directions to illumination in all directions with no directivity, when viewing the same image on the left and right, it is possible to locate at any position by using diffuse illumination with no directivity similar to a normal display device. However, an observable display device is possible.

  As another means, the luminance in the front direction can be secured by increasing the viewing angle of one of the directional illuminations in two directions.

  FIG. 6 is a diagram showing a basic configuration for realizing directional illumination in three directions, and includes a first light source 20 and a first light guide plate 21 for emitting a first light beam, and a second light beam. The second light source 25 and the second light guide plate 22 for emitting the light, and the third light source 29 and the third light guide plate 23 for emitting the third light flux, which are sequentially stacked and arranged, The second light flux passes through the first light guide plate 21, the third light flux passes through the first light guide plate 21 and the second light guide plate 22, and the emission directions of the light fluxes are different.

  FIG. 26 is an enlarged view showing a slope portion of the light guide plate. Considering the first and second light guide plates, FIG. 26 is a light guide plate that illuminates in the first observation direction when the horizontally incident light is used as a reference. A light beam 30 exiting vertically in the figure, which is the boundary of the observation region, becomes a boundary without crosstalk. At this time, the angle θ of the slope portion 31 is 45 degrees.

In addition, if the light beam reflected by the inclined surface portion 31 satisfies the total reflection condition on the front surface of the light guide plate, the light beam cannot be emitted from the light guide plate. When the angle condition is calculated,
n · sin (90−2θ) <1, that is, n · cos 2θ <1
From the above, in order to efficiently illuminate the first observation direction and the second observation direction without crosstalk, the condition of the angle θ of the inclined surface portion 31 is
θ <45 degrees, n · cos 2θ <1
It can be seen that Incidentally, when n = 1.5, 24 degrees <θ <45 degrees. In particular, when the first and second observer directions are set to 30 degrees with respect to the normal line of the display element, it is desirable to set θ to 30 degrees to 40 degrees. It is more desirable to satisfy 34 degrees <θ <38 degrees. On the other hand, since the third light guide plate guides light toward the front, it is desirable that θ = approximately 45 degrees.

  As described above, the light guide plate having a directivity direction has a three-plate structure in which the second light guide plate (first light guide plate 21 and second light guide plate 22) is added with the third light guide plate 23 for illuminating in the front direction. Therefore, it is possible to cope with observation from the front. Since both the first and second light guide plates 21 and 22 are structured to transmit light from below, they can be used even when a plurality of sheets are stacked. Further, the images that can be observed from the front differ at the timing when the third light source 29 of the third light guide plate 23 is turned on. For example, the first and second images are alternately displayed on the display element. By turning on and off at the same timing as the first light source 20, the first image can be observed in the front, and the second light source 25. By turning ON / OFF at the same timing, the second image can be observed in the front. Furthermore, by alternately displaying the first, second, and third images on the display element, different images (first image illumination 26, second image illumination 27, and third image illumination 28) are observed in three directions. It is also possible to do.

  Next, a method for narrowing the field of view only in the center when performing directional illumination in three directions will be described. FIG. 7 shows an example in which the video display device of the present invention is mounted in a vehicle as an in-vehicle monitor 200. By setting the passenger seat at the position of the first observer 201, the driver's seat at the position of the second observer 202, and the rear center seat at the position of the third observer 203, the observation range 203 of the first image The observation range 205 for the second image and the observation range 204 for the third image are determined, and images corresponding to the passenger in the passenger seat, the driver, and the passenger in the rear central seat can be observed. For example, while providing a car navigation image and a driving assistance image to the driver, at the same time, various images such as a TV image, a DVD image, a game, and various information retrieval can be provided to the passenger in the passenger seat. As a result, even if images such as TV and movies that are restricted for viewing while driving are provided only to the passenger seat, passengers in the passenger seat can watch TV and movies even when the car is moving. You can watch the video.

  In the above-described three-way directional lighting, in consideration of use in the vehicle, the viewing angle in the front direction on the premise of use from the rear seat may be smaller than the viewing angle required by the driver seat and the passenger seat side. . Therefore, when considering the illumination configuration in which the viewing angle in the front direction is smaller than the viewing angle in the other direction, a configuration as shown in FIG. 8 can be considered.

  FIG. 8 shows an example in which a diffusion plate is used as the first configuration for narrowing the angle of the visual field in the central direction. FIG. 8 shows a configuration of three light guide plates. A third light guide plate 23 having directivity in the front direction is disposed on the foremost side, and the first light guide plate 21 and the second light guide plate are located behind it. 22 are arranged. Further, a diffusion plate 130 is disposed between the third light guide plate 23 and the first light guide plate 21. As a result, the illumination from the third light guide plate 23 disposed in front of the diffusion plate 130 has a small diffusion angle due to a small diffusion (third video illumination range 28 ′), and is disposed behind the diffusion plate 130. The illumination from the light guide plates 21 and 22 has a large diffusion and a wide viewing angle (first video illumination range 26 ′, second video illumination range 27 ′).

  Thus, by arranging the third light guide plate 23 for illumination in the front direction in front, illumination with a small viewing angle is possible only in the front direction.

  FIG. 9 shows an example in which a visual field selection element is used as a second configuration for narrowing the visual field angle in the central direction. Here, the visual field selection element 31 is disposed on the forefront of the three light guide plates 21 to 23. The field-of-view selection element 31 is an element designed to transmit incident light from one direction as it is and diffuse incident light from another direction, and is generally known. What is used here is an element that has a function of diffusing light that enters perpendicularly and that diffuses light that enters at an angle. As a result, the third image illumination range that is the front direction is narrow, and the first and second image ranges can be illuminated with a wide observation range.

  FIG. 10 is a diagram for explaining an example of the drive timing of the video display device capable of displaying the video corresponding to each of the three observers. In addition to the drive timing example described in FIG. An example in which a light source is added is shown. The first image (A) and the second image (B) are alternately displayed on the transmissive display element 24, and the first light source 20 that is a light source for the first light guide plate 21 and the second light guide plate 22. The image to be observed is determined by the ON / OFF timing of the second light source 25 that is a light source for the third light source and the third light source 29 that is a light source for the third light guide plate 23. The first light source 20 is turned on only when the first video (A) is displayed. In this case, the first observer can observe only the first video. On the other hand, the second light source 25 is turned on only when the second image (B) is displayed. In this case, the second observer can observe only the second image. The images that can be observed are also switched by switching the timings of the first light source 20 and the second light source 25.

  FIG. 10 shows that the same image as that of the first observer can be observed in the front direction by setting the third light source 29 at the same timing as the first light source 20. On the contrary, if the third light source 29 is driven at the same timing as the second light source 25, the same image as the second observer can be observed.

  As an application example, by turning on the first, second, and third light sources in accordance with respective video display timings, the first video (A), the second video (B), and the third video are alternately displayed on the display element. It is possible to display and observe images with different images (C). FIG. 11 shows such a driving example.

  FIG. 27 is an example of a block diagram for performing such display. As shown in FIG. 27, the video signals A, B, C from the three video signal input means 401, 402, 403 are supplied to the display panel 407 via the high-speed video switching signal processing means 405. On the other hand, the light emission of the light sources A (408), B (409), and C (410) is controlled by the light source light emission timing control means 406. The high-speed video switching signal processing means 405 and the light source light emission timing control means 406 are controlled by the synchronization control means 404.

  As shown in FIG. 11, the video signals A, B, and C from the video signal input means 401, 402, and 403 are processed by the high-speed video switching signal processing means 405 that receives the control signal from the synchronization control means 404, Video signals A, B, and C are repeatedly supplied in this order to the display panel 407, and an image corresponding to each video signal is displayed.

  On the other hand, the light sources A (408), B (409), and C (410) are controlled by the light source emission timing control means 406 that receives the control signal from the synchronization control means 404, and an image based on the video signal A is displayed on the display panel 407. The light source A (408) is turned on in synchronization with the image signal B, the light source B (409) is turned on in synchronization with the image based on the video signal B being displayed on the display panel 407, and the image based on the video signal C is displayed. The light source C (410) is turned on in synchronization with the display on the panel 407. For this reason, each image is observed in a direction in which light is emitted by the light sources A (408), B (409), and C (410), and images different in three directions can be switched and distributed at high speed. Each of the light sources A (408), B (409), and C (410) is turned off slightly earlier than the timing at which the corresponding image is completely switched to the next image, and other images are to be observed in a certain direction. It prevents the images to be observed in the direction from mixing.

  Furthermore, if there is no observer in the observation area, turning off the light source corresponding to that area reduces power consumption or eliminates reflection on the window glass caused by emitting extra light. Can do. Instead of turning off the light source, a video corresponding to the area may be a black image.

  Next, a method for switching between directional illumination in two directions and diffuse illumination will be described. FIG. 12 shows a configuration in which a diffuse transmission element is arranged on the front surface of the light guide plate in order to switch between directional illumination in two directions and diffuse illumination. In this configuration, it is possible to switch between illumination means for viewing different images in two directions and illumination means for observing the same image in two directions. By disposing a diffuse transmission element 32 that can be turned ON / OFF by a switch 37 in front of the first and second light guide plates 21 and 22, light is not diffused as it is when the diffusion transmission element 32 is in the ON state. Since the transmitted light is diffused when the diffuse transmission element 32 is in the OFF state, the directivity is lost and the luminance distribution is easy to see from any direction. .

  As an example of the diffuse transmission element 32, there can be used an element capable of adjusting the degree of diffusion of light by ON / OFF of the voltage, which is a sheet-like element enclosing liquid crystal as disclosed in JP-A-5-188353. .

  FIG. 13 shows a configuration in which a diffusion backlight is disposed on the back surface of the light guide plate in order to switch between directional illumination in two directions and diffusion illumination. In this configuration, the first and second light guide plates 21 and 22 are disposed, and the diffusion backlight 33 is disposed behind the light guide plates 21 and 22. The directional illumination in two directions is obtained by the first and second light guide plates 21 and 22, but when switching to diffuse illumination, if the diffusibility of the diffuse backlight 33 is sufficient, the first and second light sources 20 are used. , 25 is turned off, a flat luminance distribution can be obtained. When the diffusibility of the diffusing backlight 33 is not sufficient, it is possible to obtain a flat luminance distribution as a whole by turning both the first and second light sources 20 and 25 on.

  Hereinafter, automatic viewing angle switching will be described with reference to FIGS. 14 (a) and 14 (b). FIG. 14A shows a case where, for example, in the configuration of FIG. 12, the diffusive transmission element 32 is turned on and the light beams from the first light guide plate 21 and the second light guide plate 22 are transmitted. A first image observation range 205 is formed by the light beam, and a second image observation range 206 is formed by the second light beam. However, when the diffusion transmission element 32 is turned OFF and the light beams from the first light guide plate 21 and the second light guide plate 22 are diffused, the same image observation range 207 is formed by the first light beam due to the diffusion action. .

  Similarly, when the first light source 20 and the second light source 25 are turned on in the configuration of FIG. 13 with the diffusion backlight 33 turned off, the first image observation range 205 and the second image as shown in FIG. An observation range 206 is formed. However, when the first light source 20 and the second light source 25 are turned off with the diffusion backlight 33 turned on, the same image observation range 207 as shown in FIG. 14B is formed.

  A method for changing the viewing angle between the first direction and the second direction will be described below. As shown in FIG. 15, when the front seat is located at the position of the first observer 201, the driver seat is located at the position of the second observer 202, and the rear seat is located at the position of the third observer 203, the first direction By changing the viewing angle between the first and second directions, the first viewer 201 and the third viewer 203 can increase the observation range 203 of the first video so that the first video can be observed. The second observer 202 can observe the second image. Therefore, the first observer 201 in the passenger seat and the third observer in the rear seat can observe the first image such as a navigation screen, for example, and the second observer 202 in the driver seat is used as an entertainment image such as a TV image. A second image can be observed.

  FIG. 16 shows the first configuration for changing the viewing angle between the first direction and the second direction, and the field selection element 31 as described in FIG. 9 is used as the first configuration of the two light guide plates 21 and 22. The field-of-view selection element 131 is disposed in A field selection element is an element designed to transmit incident light from one direction as it is and diffuse light incident from another direction, and is generally known. Accordingly, only the illumination light from the first light guide plate 21 can be greatly diffused, and the illumination light from the second light guide plate 22 can be prevented from being diffused. As a result, the first video illumination range 26 ′ is widened, The two-image illumination range 27 ′ can be narrowed.

  FIG. 17 shows a second configuration for changing the viewing angle between the first direction and the second direction. The first diffusion plate 34 is disposed on the front surface of the first light guide plate 21, and the second light guide plate 22 The second diffusion plate 35 is disposed on the front surface. According to such a configuration, the light emitted from the first light guide plate 21 is transmitted through the two diffusion plates of the first diffusion plate 34 and the second diffusion plate 35, resulting in a larger diffusion angle. Large first video illumination range 26 'is obtained. On the other hand, since the light emitted from the second light guide plate 22 is transmitted through only one diffusion plate of the second diffusion plate 35, the light is diffused smaller than the first image illumination range 26 ′. The range 27 'is narrow.

  A method for changing the position of the viewing angle will be described below. FIGS. 18A and 18B show how the observation angles of the first observer 201 and the second observer 202 change depending on the place where the display element 24 is arranged. Therefore, it is desirable to be able to correct such an observation position shift.

  FIG. 19 shows a first configuration for correcting the shift of the observation position. Here, the displacement of the observation position is corrected by replacing the current first light guide plate 21 or the second light guide plate 22 with another light guide plate having a different emission angle. The emission angle mainly from the light guide plate is determined by the angle of the inclined surface portion where the light is reflected in the specific configuration example of FIG. Therefore, by replacing the light guide plate with a different slope angle, it is possible to set the video observation range in an optimum direction for each observer according to the position where the display element 24 is arranged. A light guide plate having an emission angle different between the first light guide plate 21 and the second light guide plate 22 can also be used.

  FIG. 20 shows a second configuration for correcting the shift of the observation position. Here, by arranging the prism sheet 36 in front of the first light guide plate 21 and the second light guide plate 22, the angle of the light emitted from the light guide plate can be changed. When the prism sheet 36 is disposed on the front surface of the first light guide plate 21, the angles of the light emitted from the first light guide plate 21 and the second light guide plate 22 are changed. On the other hand, by arranging the prism sheet 36 between the first light guide plate 21 and the second light guide plate 22, it is possible to change the angle of only the light emitted from the second light guide plate 22.

  In the following, an embodiment of another application in which the directivity at the center of the three-directional directional light guide plate is widened will be described. In the description of FIG. 7, assuming a vehicle-mounted application, a three-way light guide plate configuration with a narrow center and a wide viewing angle in the left-right direction is shown. In the following, a configuration and application of a light guide plate having a wide central viewing angle and narrow left and right viewing angles will be described.

  FIG. 21 shows a configuration example in which the center has a wide viewing angle. In this configuration, of the three light guide plates (the first light guide plate 21, the second light guide plate 22, and the third light guide plate 23), only the third light guide plate 23 for emitting in the front direction is behind the diffusion plate 130. In addition, the first and second light guide plates 21 and 22 for emitting left and right are arranged in front of the diffusion plate 130. Therefore, the emitted light in the front direction is greatly diffused to have a wide viewing angle, and the emitted light in the left-right direction has a narrow viewing angle.

  FIG. 22 shows an application example in which the center has a wide viewing angle. When the present invention is used for a display device 350 for a passage disposed on a wall 251 such as a passage 250, a display image 2 that a passer-by 302 observes from a forward route and a display image 3 that a passer-by 301 observes from the front. The display image 1 that the passerby 300 observes from the return path can be prepared on one display screen. Conventionally, it has been impossible to change the guidance and advertisements displayed in the direction of the people who come and go, and two display devices have been required to display both. As shown in FIG. 22, if there is a display device 350 that can display different images depending on the direction of traffic, information can be transmitted to passers more efficiently.

  In the case of observing the display screen from the front, as shown in FIG. 22, observation is performed from a location relatively close to the screen, and a wide viewing angle is required. On the other hand, when a person passing from the left and right observes the display screen, the person is relatively away from the screen, and the viewing angle is limited, so that a narrow viewing angle can be handled.

  FIG. 23 shows an example of an image observed according to the viewing direction. From the passer-by 300, the destination display guidance “example: station” in the traveling direction is displayed, and the passer-by 302 also displays the destination display guidance “example: city hall” in the traveling direction. On the other hand, the passerby 301 at the front position displays “example: advertisement” so that advertisements and the like can be observed, and information corresponding to each position can be provided by one display device.

  Next, a configuration example for making the directivity angle different in the first direction and the second direction will be described. FIGS. 24A and 24B show an embodiment in which the NA (Numerical Aperture) of the light source incident on the light guide plate is changed. FIG. 24A shows a case where NA is reduced when directivity is small, and FIG. 24B shows a case where NA is increased when directivity is large.

  Light is incident from the end surface of the light guide plate 302 by the light source 300 and the illumination lens 301, and the field of view of the reflected light from the inclined surface 303 of the light guide plate 302 and the emitted light from the light guide plate 302 increases as the NA at that time increases. It is possible to increase the corner.

  Furthermore, it is possible to perform illumination having different directivities depending on the observation direction by making light having different NAs incident on the end surfaces of at least two light guide plates. That is, as shown in FIG. 24C, the light from the first light source 300-1 is incident on the first light guide plate 302-1 through the first illumination lens 301-1, and then emitted with a large viewing angle. Then, the light from the second light source 300-2 is incident on the second light guide plate 302-2 via the second illumination lens 301-2 and then emitted with a small viewing angle.

  Furthermore, a mechanism that can change the size of the viewing angle can be realized by making the light source position and the illumination lens position variable.

  Next, a configuration for changing the slope shape of the light guide plate will be described with reference to FIG. As shown in FIG. 25A, when the slope portion 304 of the light guide plate 302 has a planar shape, the reflection angle of light incident on the slope portion 304 is uniform, and the directivity of light emitted from the light guide plate 302 is Narrow (small viewing angle). On the other hand, if the slope portion of the light guide plate 302 has a curved shape, the reflection angle of light incident on the slope portion is reflected at various angles depending on the surface position of the slope portion. Sex is wide. Examples of the curved surface include a convex slope 305 as shown in FIG. 25B and a concave slope 306 as shown in FIG.

  Furthermore, by using a light guide plate having a different slope shape with at least two light guide plates, illumination having different directivities depending on the observation direction can be performed.

  According to the above-described embodiment, there is an effect that the cost is low, the crosstalk is small, and the illumination unevenness is small.

It is the figure which represented the observable range of the image | video inject | emitted from the display panel 24 which can display the image | video corresponding to two observers with a horizontal cross section. It is a figure which shows schematic structure of the video display apparatus which can display the image | video corresponding to each to two observers. It is a horizontal sectional view of the illumination means of the video display apparatus which can display the image | video corresponding to each to two observers. It is a schematic diagram which shows the concrete cross-section of the video display apparatus which can display the image | video corresponding to each to two observers. It is a figure for demonstrating an example of the drive timing of the video display apparatus which can display the image | video corresponding to each of two observers. It is a figure which shows the basic composition for implement | achieving directional illumination of 3 directions. It is a figure which shows the example at the time of mounting the video display apparatus of this invention in the vehicle as the vehicle-mounted monitor 200. FIG. It is a figure which shows the structure of the illumination that the viewing angle of a front direction becomes smaller than the viewing angle of another direction. It is a figure which shows the example which used the visual field selection element as the 2nd structure for narrowing the angle of the visual field of a center direction. It is a figure for demonstrating an example of the drive timing of the video display apparatus which can display the image | video corresponding to each to three observers. Timing for turning on the first, second, and third light sources in accordance with the respective video display timings in order to display different videos of the first video (A), the second video (B), and the third video (C). FIG. It is a figure which shows the structure which arrange | positions a diffuse transmission element in the front surface of a light-guide plate in order to switch directional illumination of 2 directions, and diffused illumination. It is a figure which shows the structure which arrange | positions a spreading | diffusion backlight on the back surface of a light-guide plate in order to switch between directional illumination of 2 directions, and diffused illumination. It is a figure for demonstrating automatic switching of a viewing angle. It is a figure for demonstrating the method to change a viewing angle with a 1st direction and a 2nd direction. It is a figure which shows the structure which has arrange | positioned the visual field selection element in order to change a viewing angle with a 1st direction and a 2nd direction. It is a figure which shows the structure which has arrange | positioned two diffuser plates in order to change a viewing angle with a 1st direction and a 2nd direction. It is a figure which shows how the observation angle of a 1st observer and a 2nd observer changes with the place where a display element is arrange | positioned. It is a figure which shows the 1st structure which correct | amends the shift | offset | difference of an observation position. It is a figure which shows the 2nd structure which correct | amends the shift | offset | difference of an observation position. It is a figure which shows the structural example whose center becomes a wide viewing angle. It is a figure which shows one application example of the structure whose center becomes a wide viewing angle. It is a figure which shows the example of an image observed by the viewing direction. It is a figure which shows embodiment which changes NA of the light source which injects into a light-guide plate. It is a figure for demonstrating the structure which changes the slope shape of a light-guide plate. It is a figure which expands and shows the slope part of a light-guide plate. It is a block diagram for displaying three images by turning on the first, second, and third light sources in accordance with each image display timing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... 1st light source, 21 ... 1st light guide plate, 22 ... 2nd light guide plate, 23 ... 3rd light guide plate, 24 ... Transmission type display element, 25 ... 2nd light source, 26 ... 1st video illumination, 27 ... 1st 2 image illumination, 28 ... 3rd image illumination, 123 ... light diffusion element.

Claims (17)

A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
Illuminating means for emitting first, second, and third light fluxes in at least three different directions in a time-sharing manner,
A first image using the first light beam emitted from the illumination means as illumination light, a second image using the second light beam as illumination light, and a first image using the third light beam as illumination light. A transmissive display element capable of displaying three images in a time-sharing manner;
Comprising
The illumination means includes
A first light source that emits the first luminous flux;
A second light source that emits the second luminous flux;
A third light source that emits the third luminous flux;
A first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer;
A second light guide plate for emitting the second light flux emitted from the second light source only in the direction of the second observer;
A third light guide plate for emitting the third light flux emitted from the third light source only in the direction of the third observer;
An image display device comprising:   At least one of the first, second, and third light beams is a central illumination light beam whose emission direction is normal to the display surface of the transmissive display element. 2. The video display device according to 1.   The image display device according to claim 2, wherein an illumination range of the central illumination light beam is different from an illumination range of other light beams.   4. The diffusion plate according to claim 1, wherein a diffusion plate is disposed between at least one of the first and second light guide plates and between the second and third light guide plates. 5. The video display device described.   The video display device according to claim 4, wherein the first light guide plate emits the central illumination light beam.   A field selection element is disposed in front of the first, second, and third light guide plates. The field selection element transmits light incident in the normal direction as it is, and diffuses light incident at an angle. The image display device according to claim 3, wherein the image display device transmits the image.   The first, second, and third light sources sequentially emit light in a time division manner, and the transmissive display element sequentially displays the first, second, and third images in a time division manner. Item 2. The video display device according to Item 1.   2. The video display device according to claim 1, wherein at least one of the first, second, and third light sources has the same lighting timing as the other light sources. A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
From the first light source, the first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the second light source At least a second light guide plate that emits the emitted second light flux only in the direction of the second observer, and emits the first and second light fluxes in at least two different directions in a time-sharing manner. Lighting means;
A transmissive display element capable of displaying, in a time-sharing manner, a first image using the first light beam emitted from the illumination means as illumination light and a second image using the second light beam as illumination light; ,
A diffusing function for diffusing the first and second light fluxes from the illuminating means, and a transmissive function for transmitting the first and second light fluxes, disposed between the illuminating means and the transmissive display element; A diffusive transmission element comprising:
Switching means for switching between the diffusion function and the transmission function of the diffusion transmission element;
An image display device comprising:   The video display device according to claim 9, wherein the diffuse transmission element is made of a nematic liquid crystal, and switching by the switching unit is performed based on ON / OFF of an applied voltage.   The video display device according to claim 9, wherein when the diffuse transmission element functions as a diffusion element, the first light flux and the second light flux are emitted simultaneously. A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
From the first light source, the first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the second light source At least a second light guide plate that emits the emitted second light flux only in the direction of the second observer, and emits the first and second light fluxes in at least two different directions in a time-sharing manner. First illumination means;
A second illuminating unit disposed behind the first illuminating unit and emitting a light beam that is transmissive through the first illuminating unit and has no directivity;
An image display device comprising: A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
From the first light source, the first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the second light source At least a second light guide plate that emits the emitted second light flux only in the direction of the second observer, and emits the first and second light fluxes in at least two different directions in a time-sharing manner, respectively. Lighting means;
A transmissive display element capable of displaying, in a time-sharing manner, a first image using the first light beam emitted from the illumination means as illumination light and a second image using the second light beam as illumination light; ,
A degree of diffusion between the illuminating means and the transmissive display element, and a degree of diffusion between the first light flux from the first light guide plate and the second light flux from the second light guide plate. A field of view selection element that can be different;
An image display device comprising: A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
A first light beam incident at a predetermined NA is emitted only in the direction of the first observer by a combination of the first light source, the first illumination lens, and the first light source and the first illumination lens. A first illumination means comprising a first light guide plate that
A second light source incident on the second light source, the second illumination lens, and a second light beam incident at a NA different from the predetermined NA by a combination of the second light source and the second illumination lens is transmitted to the second observer. A second illumination means comprising a second light guide plate that emits only in the direction of
A first image using the first light beam emitted from the first illumination means as illumination light, and a second image using the second light beam emitted from the second illumination means as illumination light And a transmissive display element capable of displaying in a time-sharing manner,
An image display device comprising: A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
A first light source, a first light guide plate having a slope portion having a predetermined shape, and emitting a first light beam emitted from the first light source only in the direction of the first observer; A second light guide that emits the second light flux emitted from the second light source only in the direction of the second observer. An illuminating means for emitting the first and second light fluxes in at least two different directions in a time-sharing manner, respectively.
A transmissive display element capable of displaying, in a time-sharing manner, a first image using the first light beam emitted from the illumination means as illumination light and a second image using the second light beam as illumination light; ,
An image display device comprising: A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
From the first light source, the first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the second light source At least a second light guide plate that emits the emitted second light flux only in the direction of the second observer, and emits the first and second light fluxes in at least two different directions in a time-sharing manner. Lighting means;
A transmissive display element capable of displaying, in a time-sharing manner, a first image using the first light beam emitted from the illumination means as illumination light and a second image using the second light beam as illumination light; ,
Comprising
The video display device, wherein the first light guide plate and the second light guide plate can be replaced with other light guide plates having different emission angles. A video display device having one display screen capable of displaying video corresponding to each of a plurality of observers,
From the first light source, the first light guide plate that emits the first light beam emitted from the first light source only in the direction of the first observer, the second light source, and the second light source At least a second light guide plate that emits the emitted second light flux only in the direction of the second observer, and emits the first and second light fluxes in at least two different directions in a time-sharing manner. Lighting means;
A transmissive display element capable of displaying, in a time-sharing manner, a first image using the first light beam emitted from the illumination means as illumination light and a second image using the second light beam as illumination light; ,
A prism sheet disposed between the illuminating means and the transmissive display element and having an action of changing an emission angle of the first light beam and an emission angle of the second light beam;
An image display device comprising:

Images