Image display device and image display method

Abstract

This image display device displays a stereoscopic image by using a parallax barrier scheme, the image display device comprising: a transmission-type image display surface on which an image having left-eye image data and an image having right-eye image data are alternately displayed; an image forming unit in which a plurality of optical members having a plurality of band-shaped patterns with optical properties are disposed on a surface positioned on the rear surface side of the image display surface; and a plurality of band-shaped light sources which are disposed on a lighting arrangement surface, which is a surface positioned on the rear surface side of the image forming unit, and which irradiate the image display surface with illumination light. Slit regions of a parallax barrier scheme are formed by an image obtained by the optical members of the image forming unit forming an image on the rear surface side of the image display surface with the illumination light from the band-shaped light sources.

Description

Technical Field

[0001] The present invention relates to an image display device and an image display method. This application claims priority based on Japanese Patent Application No. 2020-175498 filed in Japan on October 19, 2020, the content of which is incorporated herein by reference.

Background Art

[0002] In recent years, research and development have been conducted on image display devices that enable stereoscopic viewing of images without using glasses. As an image display device that enables stereoscopic viewing of images without using glasses, for example, a naked-eye stereoscopic video display device using a parallax barrier method by time division is known (Patent Document 1). In the naked-eye stereoscopic video display device described in Patent Document 1, two liquid crystal panels are stacked, and a right-eye image and a left-eye image are alternately displayed on one of the liquid crystal panels, and a parallax barrier is displayed on the other of the liquid crystal panels (referred to as an active parallax barrier method).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the naked-eye stereoscopic video display device described in Patent Document 1, since two liquid crystal panels are stacked and used, the transmittance of illumination light is lowered. Therefore, in the naked-eye stereoscopic video display device described in Patent Document 1, it has been necessary to use a backlight with very high brightness and high power consumption. There has been a demand for reducing power consumption in an image display device that displays a stereoscopic image by a parallax barrier method.

[0005] The present invention has been made in view of the above points, and provides an image display device capable of reducing power consumption in an image display device that displays a stereoscopic image by a parallax barrier method, and an image display method.

Means for Solving the Problems

[0006] The present invention has been made to solve the above problems, and one aspect of the present invention is an image display device that displays a stereoscopic image by a parallax barrier method, including a transmissive image display surface on which an image of left-eye image data and an image of right-eye image data are alternately displayed, and an imaging unit in which a plurality of optical members having a plurality of strip-shaped optical characteristic patterns are arranged on a surface located on the back side of the image display surface, and a plurality of strip-shaped light sources arranged on an illumination arrangement surface that is a surface located on the back side of the imaging unit and irradiates the image display surface with illumination light, wherein the slit region of the parallax barrier method is formed by an image obtained by imaging illumination light from the strip-shaped light source on the back side of the image display surface by the optical member included in the imaging unit. In the following, the columnar optical member will be described as a lenticular lens.

[0007] Another aspect of the present invention is the above image display device, wherein the parallax barrier method is a time-division parallax barrier method, and an illumination arrangement surface control unit that changes the arrangement of a light-emitting region that generates the illumination light in the illumination arrangement surface by changing which of the plurality of strip-shaped light sources emits light, and an image display surface control unit that controls the image display surface based on the left-eye image data and the right-eye image data are further provided, and the image display surface control unit controls each of a left image region on the image display surface where the image of the left-eye image data is displayed and a right image region on the image display surface where the image of the right-eye image data is displayed according to the arrangement of the slit region that changes according to the arrangement of the light-emitting region.

[0008] Further, in one aspect of the present invention, in the above-described image display device, a position information acquisition unit that acquires position information indicating an observer distance, which is the distance between at least one of the two eyes of an observer observing the image display surface and the image display surface, is further provided, and the image display surface control unit controls each of the left image region and the right image region based on the observer distance indicated by the position information acquired by the position information acquisition unit.

[0009] Further, in one aspect of the present invention, in the above-described image display device, when the number of divisions of the time division is n, a relationship represented by Expression (2) holds among a distance D, which is the distance between the light source and the imaging unit, a distance d, which is the distance between the imaging unit and the back side of the image display surface, a slit width w, which is the width of the slit region, and a pitch Wl, which is the distance between the centers of adjacent optical members arranged in a plurality in the imaging unit.

[0010] Further, in one aspect of the present invention, in the above-described image display device, the arrangement of the light emitting region that generates the illumination light in the illumination arrangement surface does not change with time.

[0011] Also, one aspect of the present invention is an image display device that displays a stereoscopic image by a parallax barrier method, including a transmissive image display surface on which images of left-eye image data and images of right-eye image data are alternately displayed, and a plurality of optical members having a plurality of strip-shaped optical property patterns are disposed on a surface located on the back side of the image display surface. An imaging unit, and a plurality of strip-shaped light sources disposed on an illumination arrangement surface that is a surface located on the back side of the imaging unit and irradiates illumination light onto the image display surface. An image display method of the image display device, including: an illumination arrangement surface control step of emitting a light source corresponding to a light emission region that generates the illumination light on the illumination arrangement surface among the plurality of strip-shaped light sources; a slit region forming step of forming a slit region of the parallax barrier method by an image obtained by imaging illumination light from the strip-shaped light source on the back side of the image display surface by the optical member included in the imaging unit; and an image display surface control step of controlling the image display surface based on the left-eye image data and the right-eye image data.

Effects of the Invention

[0012] According to the present invention, power consumption can be reduced in an image display device that displays a stereoscopic image by a parallax barrier method.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Figure 8

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Figure 10

Figure 11

Modes for Carrying Out the Invention

[0014] (Embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For convenience of explanation, the drawings show an XYZ orthogonal coordinate system, which is a three-dimensional orthogonal coordinate system. In the XYZ orthogonal coordinate system, the direction of the Z-axis is vertically upward. In the following description, the direction parallel to the Z-axis is also referred to as the vertical direction. The direction of the Z-axis is also referred to as the upward direction. The direction opposite to the direction of the Z-axis is also referred to as the downward direction. The positive side in the direction of the Z-axis is also referred to as the upper side, and the negative side in the direction of the Z-axis is also referred to as the lower side. The direction parallel to the X-axis is also referred to as the depth direction. The positive side in the direction of the X-axis is also referred to as the front side, and the negative side in the direction of the X-axis is also referred to as the back side. The direction parallel to the Y-axis is also referred to as the left-right direction. The positive side in the direction of the Y-axis is also referred to as the right side, and the negative side in the direction of the Y-axis is also referred to as the left side.

[0015] [Configuration of Parallax Barrier] FIG. 1 is a diagram showing an example of the configuration of a parallax barrier PB according to the present embodiment. In the present embodiment, an example in the case where the parallax barrier method is the time-division parallax barrier method will be described. Note that in the present embodiment, an example in the case where the number of time divisions in the time-division parallax barrier method is 4 will be described, but the same applies to cases where the number of time divisions is other than 4. Also, in the following description, the number of time divisions is simply referred to as the number of divisions. The parallax barrier PB according to the present embodiment is realized using a light source unit LE and a lenticular lens LL.

[0016] The light source unit LE includes a plurality of strip-shaped light sources LB. Here, strip-shaped means an elongated shape having a constant width like a strip. The strip shape is also referred to as a rectangular shape. In FIG. 1, as the plurality of strip-shaped light sources LB, strip-shaped light sources LB1-1 to LB1-4 and strip-shaped light sources LB2-1 to LB2-4 are shown. The plurality of strip-shaped light sources LB irradiate illumination light onto an image display surface DS (not shown in FIG. 1). The strip-shaped light source LB, as an example, includes a light emitting diode (LED). The plurality of strip-shaped light sources LB are arranged on an illumination arrangement surface LS (not shown in FIG. 1 or shown in FIG. 2), which is a surface located on the back side of the imaging unit, and is an example of a plurality of strip-shaped light sources that irradiate illumination light onto the image display surface DS. Note that the strip-shaped light source LB may include a laser diode (LD, also referred to as a semiconductor laser) having a radiation angle of a predetermined magnitude or more instead of the LED.

[0017] Referring now to FIG. 2, the arrangement of a plurality of strip-shaped light sources LB will be described. FIG. 2 is a diagram showing an example of the arrangement of a plurality of strip-shaped light sources LB according to the present embodiment. In FIG. 2, strip-shaped light sources LB1-1, LB1-2, LB1-3, and LB1-4 among the plurality of strip-shaped light sources LB are shown. As shown in FIG. 2, the plurality of strip-shaped light sources LB are inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS. The shape of the strip-shaped light source LB is a substantially parallelogram. The parallelogram has a long side in the vertical direction of the illumination arrangement surface LS. Note that the strip shape is also referred to as a rod shape. In the light source unit LE, a plurality of strip-shaped light sources LB are arranged side by side on the illumination arrangement surface LS. The plurality of strip-shaped light sources LB are arranged adjacent to each other substantially in parallel.

[0018] The illumination arrangement surface LS is a control surface for variably controlling the arrangement of illumination light irradiated onto the image display surface DS from the back of the image display surface DS with respect to the image display surface DS. In the time-division parallax barrier method, in accordance with the fact that the number of divisions is 4, one strip-shaped light source that emits light is periodically changed in a predetermined order in units of four strip-shaped light sources. In FIG. 2, in the example shown in FIG. 2, the strip-shaped light source LB1-1 is emitting light, and the strip-shaped light sources LB1-2, LB1-3, and LB1-4 are not emitting light. The same applies to the strip-shaped light sources other than the strip-shaped light sources LB1-1, LB1-2, LB1-3, and LB1-4 among the plurality of strip-shaped light sources LB. Note that the width of the illumination arrangement surface LS (the length in the left-right direction, that is, the length in the direction of the Y axis) may be substantially equal to the width of the image display surface DS or may be wider by a predetermined width than the width of the image display surface DS.

[0019] In the present embodiment, a plurality of illumination arrangement control elements (not shown) are arranged in a matrix on the illumination arrangement surface LS. The plurality of strip-shaped light sources LB are realized as light emission patterns obtained by each of the plurality of illumination arrangement control elements controlling a plurality of LEDs. Note that, as the configuration of the light source unit LE, instead of a configuration in which a plurality of illumination arrangement control elements are arranged in a matrix on the illumination arrangement surface LS, a configuration in which a plurality of strip-shaped (or rod-shaped) lights are arranged side by side may be used.

[0020] As described above, the plurality of strip-shaped light sources LB are inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS. When the plurality of strip-shaped light sources LB are not inclined by a predetermined angle with respect to the vertical direction, the slit region of the parallax barrier PB can only be translated at a distance with one sub-pixel as a unit. On the other hand, when the plurality of strip-shaped light sources LB are inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS as in the present embodiment, the slit region of the parallax barrier PB can be translated at a distance greater than 0 and equal to or less than one sub-pixel. That is, when the plurality of strip-shaped light sources LB are inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS, the position of the slit region can be translated by a finer distance compared to the case where it is not inclined.

[0021] Note that the plurality of strip-shaped light sources LB do not necessarily have to be inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS. That is, the plurality of strip-shaped light sources LB may be arranged substantially parallel to the vertical direction on the illumination arrangement surface LS.

[0022] Returning to FIG. 1, the description of the configuration of the parallax barrier PB will be continued. The lenticular lens LL is arranged on the side of the image display surface DS (that is, the front side) rather than the light source unit LE. The lenticular lens LL includes a plurality of element lenses LU. The element lens LU is a convex lens having a shape of a column with a substantially semi-circular bottom surface. In the lenticular lens LL, the plurality of element lenses LU are arranged adjacent to each other substantially parallel to each other in the height direction of the column of the element lens LU in a planar manner.

[0023] When illumination light irradiated from a plurality of strip-shaped light sources LB is incident on the lenticular lens LL, the lenticular lens LL forms an image of the illumination light on the back side of the image display surface DS. In the parallax barrier PB according to the present embodiment, an image obtained by forming an image of the illumination light from the strip-shaped light source LB on the back side of the image display surface DS by the element lens LU included in the lenticular lens LL is used as a slit region of the parallax barrier method. The focal length of the element lens LU is a predetermined focal length selected according to a predetermined position where the parallax barrier PB is arranged.

[0024] In addition, the longitudinal direction of the strip shape of the strip-shaped light source LB and the columnar height direction of the element lens LU included in the lenticular lens LL are substantially parallel. In the present embodiment, in response to the plurality of strip-shaped light sources LB being inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS, the element lens LU included in the lenticular lens LL has the columnar height direction of the element lens LU inclined by the predetermined angle with respect to the vertical direction on the illumination arrangement surface LS and is arranged on a surface located closer to the image display surface DS than the light source unit LE.

[0025] The lenticular lens LL is an example of an imaging unit in which a plurality of optical members each having a plurality of strip-shaped optical property patterns are arranged on a surface located on the back side of the image display surface DS. Note that any optical member that forms an image of illumination light from the strip-shaped light source LB on the back side of the image display surface DS can be used as the imaging unit instead of the lenticular lens LL. That is, an optical member having optical properties equivalent to those of the lenticular lens LL in which a plurality of element lenses LU are arranged may be used instead of the lenticular lens LL. The optical properties equivalent to those of the lenticular lens LL are optical properties that do not change in the vertical direction (or, when a plurality of strip-shaped light sources LB are inclined by a predetermined angle with respect to the vertical direction on the illumination arrangement surface LS as in the present embodiment, in the direction inclined by the predetermined angle). The optical properties include, for example, refractive index and / or transmittance. For example, instead of the element lens LU, a columnar plano-lens in which the refractive index is changed within the lens may be used. Further, for example, a plate-shaped (rectangular parallelepiped shape) optical member made of a plurality of types of materials, in which the pattern of the distribution of the refractive index values is strip-shaped, that is, an optical member in which the refractive index changes at a predetermined interval only in the left-right direction and is constant in the vertical direction may be used.

[0026] Here, referring to FIG. 3, the relationship between the width of the strip-shaped light source LB and the width of the slit region of the parallax barrier PB will be described. FIG. 3 is a diagram showing an example of the relationship between the width of the strip-shaped light source LB and the width of the slit region according to the present embodiment. The length of the short side of the parallelogram, which is the shape of the strip-shaped light source LB, is defined as the width of the strip-shaped light source LB. Let the width of the strip-shaped light source LB be width W. Let the distance in the depth direction between the light source unit LE and the lenticular lens LL be distance D. Let the distance in the depth direction between the lenticular lens LL and the parallax barrier PB be distance d. Let the width of the slit region of the parallax barrier PB be slit width w. A relationship expressed by Equation (1) holds among distance D, distance d, width W, and slit width w due to the similarity of triangles.

[0027]

Equation

[0028] Here, the distance D is longer than the distance d, and the width W is longer than the slit width w. That is, in the parallax barrier PB, a slit width w shorter than the width W of the plurality of strip-shaped light sources LB arranged in the light source unit LE is realized. The longer the distance D is compared to the distance d, the shorter the slit width w is compared to the width W. Therefore, by increasing the distance D between the light source unit LE and the lenticular lens LL, a narrow slit region is formed in the parallax barrier PB.

[0029] Here, in the lenticular lens LL, the distance between the centers of the plurality of element lenses LU is referred to as the pitch Wl of the element lens LU. A relationship represented by Equation (2) holds among the distance D, the distance d, the slit width w, and the pitch Wl.

[0030]

Equation

[0031] In Equation (2), the number n indicates the number of divisions. When the relationship represented by Equation (2) holds, the slit regions formed by the images of the illumination light from different strip-shaped light sources LB completely overlap. (See Figure 4) On the other hand, when the relationship represented by Equation (2) does not hold 、 s parts that do not overlap occur between the slit regions. That is , only a part of the slit region formed by the image of the illumination light from the strip-shaped light source LB1-1 and the slit region formed by the image of the illumination light from the strip-shaped light source LB2-1 overlap, and non-overlapping parts occur u .

[0032] Referring now to FIG. 5, a pattern in which the slit region of the parallax barrier PB changes will be described. FIG. 5 is a diagram showing an example of a pattern in which the parallax barrier PB according to the present embodiment changes. As described above, a plurality of illumination arrangement control elements are arranged in a matrix on the illumination arrangement surface LS to control a plurality of LEDs. Therefore, in the light source unit LE, the light emission pattern of the strip light source LB can be changed at high speed. Since the parallax barrier PB is an image of the illumination light from the strip light source LB formed by the lenticular lens LL, the position and / or width can be changed by changing the light emission patterns of the plurality of strip light sources LB on the illumination arrangement surface LS at high speed. Alternatively, the parallax barrier PB can be blinked.

[0033] In FIG. 5, the light emission pattern of the strip light source LB changes in the order of FIGS. 5(A), 5(B), 5(C), and 5(D), and the pattern of the position of the slit region of the parallax barrier PB changes according to each light emission pattern.

[0034] Note that in FIG. 5, for the sake of easy viewing of the change in the pattern of the position of the slit region, the case where the distance between the light source unit LE and the lenticular lens LL is not sufficiently long compared to the distance between the lenticular lens LL and the parallax barrier PB is illustrated. Although the parallax barrier PB shown in FIG. 5 is indicated by a plurality of dots, when the distance between the light source unit LE and the lenticular lens LL is sufficiently long compared to the distance between the lenticular lens LL and the parallax barrier PB, a slit region having a width of about the pitch of the plurality of dots is realized. Also note that in FIG. 5, for the sake of easy viewing of the change in the pattern of the position of the slit region, the case where the slit regions, which are images of the illumination light from different strip light sources LB, overlap is shown.

[0035] [Configuration of Image Display System] FIG. 6 is a diagram showing an example of the configuration of the image display system 1 according to the present embodiment. The image display system 1 is a system for displaying a stereoscopic image by the above-described parallax barrier PB. The image display system 1 includes an image display device 10. The image display device 10 displays a stereoscopic image by a parallax barrier method using time division. The image display device 10 includes a display unit 2, an irradiation unit 3, and a control device 4.

[0036] The display unit 2 includes a transmissive image display surface DS on which images of left-eye image data and images of right-eye image data are alternately displayed. The display unit 2 includes a liquid crystal display (LCD) as the image display surface DS. The irradiation unit 3 includes the above-described light source unit LE and a lenticular lens LL. In the example shown in FIG. 6, the illumination arrangement surface LS provided in the light source unit LE includes an LCD instead of an illumination arrangement surface in which LEDs are arranged in a matrix. The sizes of the LCDs provided on the image display surface DS and the illumination arrangement surface LS are both 24 inches.

[0037] In an example shown in FIG. 6, the distance between the light source unit LE and the lenticular lens LL is 100 mm. The distance between the lenticular lens LL and the image display surface DS is 6.5 mm. The number of pixels of the illumination arrangement surface LS is 1920×1080 pixels. The width of the strip-shaped light source LB provided in the light source unit LE is 25 mm. The pitch of the element lens LU is 0.7 mm. The radius of the substantially semi-circular bottom surface of the element lens LU having a columnar shape is 0.5 mm.

[0038] The control device 4 controls the entire image display device 1. The control device 4 performs control of each of the display unit 2 and the irradiation unit 3. The control device 4 is, for example, a personal computer (PC). The observer H observes the image display surface DS. The observer H observes the image display surface DS from a position where the distance between at least one of his own eyes and the image display surface DS is 800 mm.

[0039] [Functional Configuration of the Control Device] Hereinafter, with reference to FIG. 7, the functional configuration of the control device 4 will be described. FIG. 7 is a diagram showing an example of the functional configuration of the control device 4 according to the present embodiment. The control device 4 includes a control unit 40 and a storage unit 41.

[0040] The control unit 40 controls the entire control device 4. The control unit 40 includes a reading unit 401, an image generation unit 402, an illumination arrangement surface control unit 403, and an image display surface control unit 404. These functional units included in the control unit 40 are realized, for example, when a CPU (Central Processing Unit) (not shown) executes various programs stored in the storage unit 41 described later. Also, some or all of the functional units may be hardware functional units such as an ASSP (Application Specific Standard Product) or an ASIC (Application Specific Integrated Circuit).

[0041] The reading unit 401 reads out various information stored in advance in the storage unit 41. The various information includes first image data and a parameter set PS. The first image data is image data of an image including parallax information. Also, the first image data may be image data of a moving image or image data of a still image. The parameter set PS includes the number of divisions, the slit width, and the inclination of the slit.

[0042] The image generation unit 402 generates left image data and right image data based on the first image data read from the storage unit 41 by the reading unit 401 and the number of divisions indicated by the parameter set PS.

[0043] The illumination arrangement surface control unit 403 controls the light source unit 30 provided in the irradiation unit 3 to generate a parallax barrier PB. The light source unit 30 has the same configuration as the above-described light source unit LE. The illumination arrangement surface control unit 403 changes the light emission pattern of the plurality of strip-shaped light sources LB by controlling a plurality of LEDs via a plurality of illumination arrangement control elements arranged on the illumination arrangement surface LS. That is, the illumination arrangement surface control unit 403 changes the arrangement of the light emission regions that generate the illumination light irradiated by the strip-shaped light sources LB on the image display surface DS by changing which of the plurality of strip-shaped light sources LB emits light.

[0044] The image display surface control unit 404 causes an image to be displayed on the image display surface DS provided in the display unit 2. The image display surface control unit 404 causes an image to be displayed based on the parameter set PS and the left image data and the right image data generated by the image generation unit 402. Here, the image display surface control unit 404 controls the image display surface DS based on the left-eye image data and the right-eye image data. The image display surface control unit 404 controls each of the left image region and the right image region according to the arrangement of the slit region that changes according to the arrangement of the light emission region on the image display surface DS. The left image region is the region on the image display surface DS where the image of the left-eye image data is displayed. The right image region is the region on the image display surface DS where the image of the right-eye image data is displayed.

[0045] In the image display device 10, by providing the illumination arrangement surface control unit 403, the light emission pattern of the plurality of strip-shaped light sources LB on the illumination arrangement surface LS can be changed at high speed, so that the position and / or the width can be changed. Alternatively, the parallax barrier PB can be blinked. Note that in the present embodiment, an example in the case where the image display device 10 includes the illumination arrangement surface control unit 403 has been described, but the present invention is not limited to this. As long as the arrangement of the light emission region on the image display surface DS can be changed by changing which of the plurality of strip-shaped light sources LB emits light, other mechanisms may be used.

[0046] In the present embodiment, an example in which the image display device 10 displays a stereoscopic image by means of a time-division parallax barrier method has been described, but the present invention is not limited to this. The image display device 10 may display a stereoscopic image by means of a static parallax barrier method. In the static parallax barrier method, the arrangement of the light-emitting regions that generate illumination light on the illumination arrangement surface LS does not change with time. That is, when displaying a stereoscopic image by means of a static parallax barrier method, the image display device 10 does not switch the position of the parallax barrier PB. In that case, the illumination arrangement surface control unit 403 may be omitted from the configuration of the image display device 10.

[0047] As described above, the image display device 10 according to the present embodiment is an image display device that displays a stereoscopic image by means of a parallax barrier method, and includes an image display surface DS, an imaging unit (in the present embodiment, a lenticular lens LL), and a plurality of strip-shaped light sources (in the present embodiment, a plurality of strip-shaped light sources LB). In the imaging unit (in the present embodiment, the lenticular lens LL), a plurality of optical members (in the present embodiment, element lenses LU) having a plurality of strip-shaped optical property patterns are arranged on the surface located on the back side of the image display surface DS. The plurality of strip-shaped light sources (in the present embodiment, the plurality of strip-shaped light sources LB) are arranged on the illumination arrangement surface LS, which is the surface located on the back side of the imaging unit (in the present embodiment, the lenticular lens LL), and irradiate the image display surface DS with illumination light. In the image display device 10 according to the present embodiment, a slit region of the parallax barrier method is formed by an image obtained by imaging illumination light from a strip-shaped light source (in the present embodiment, a strip-shaped light source LB) on the back side of the image display surface DS by the optical member (in the present embodiment, an element lens LU) included in the imaging unit (in the present embodiment, the lenticular lens LL).

[0048] With this configuration, in the image display device 10 according to the present embodiment, since the parallax barrier PB is an image formed by the illumination light being imaged by the convex lens (lenticular lens LL), it is not necessary to use an LCD or the like to form the parallax barrier as in the prior art (for example, Patent Document 1). Therefore, in an image display device that displays a stereoscopic image by the time-division parallax barrier method, power consumption can be reduced.

[0049] In a conventional naked-eye stereoscopic video display device, since two liquid crystal panels (one for displaying the parallax barrier and the other for displaying the image) are used in an overlapping manner, the transmittance of the illumination light has become low. Therefore, in a conventional naked-eye stereoscopic video display device, it has been necessary to use a backlight with very high brightness and high power consumption. In the image display device 10, the illumination light from the light source unit LE only needs to have a brightness sufficient to pass through the lenticular lens LL. Therefore, compared with the case of overlapping two liquid crystal panels, power consumption can be significantly reduced. Here, the visible light transmittance of the lenticular lens LL is approximately 90% or more, while the visible light transmittance of the liquid crystal panel is at most about 20 to 30%.

[0050] Also, in a conventional naked-eye stereoscopic video display device, the liquid crystal panel is made to emit light and used as a so-called backlight. In that case, even though there is a difference in brightness between the slit region and the barrier region, all the elements of the liquid crystal panel are made to emit light. In the image display device 10, only the light-emitting region is made to emit light on the illumination arrangement surface LS. That is, in the image display device 10, the area of the region that emits light on the illumination arrangement surface becomes one divided by the number of divisions compared to the conventional case. Therefore, in the image display device 10, only about one divided by the number of divisions of the power consumption compared to the conventional case is required.

[0051] (Modification example) Hereinafter, a modification example of the above embodiment will be described in detail with reference to the drawings. There may be a case where the distance between the observer H and the image display surface DS changes. In that case, in order to suppress crosstalk between the left-eye image and the right-eye image, it is necessary to change the number of time divisions according to the distance. Here, as described above, in a conventional autostereoscopic display device, the parallax barrier was displayed as an image on a display surface such as an LCD. Therefore, in the conventional autostereoscopic display device, by controlling the pixels of the display surface, the width of the slit region was changed according to the change in the number of divisions.

[0052] As described above, in the image display device 10 according to the embodiment, the parallax barrier PB is an image formed by the illumination light through the convex lens. Therefore, in the image display device 10, when the distance between the observer H and the image display surface DS changes, instead of changing the slit width, it is conceivable to change the image displayed on the image display surface DS. In this modification, a case will be described in which the left-eye image and the right-eye image displayed on the image display surface DS are controlled according to the distance between the observer H and the image display surface DS.

[0053] FIG. 8 is a diagram showing an example of crosstalk according to the present embodiment. There may be a case where the slit width of the slit region of the parallax barrier PB does not match the width of the pixels provided on the image display surface DS. In that case, as shown in FIG. 8, crosstalk may occur between the left-eye image and the right-eye image. Crosstalk between the left-eye image and the right-eye image means that the illumination light transmitted through the pixels on which the left-eye image is displayed enters the right eye, or the illumination light transmitted through the pixels on which the right-eye image is displayed enters the left eye.

[0054] In FIG. 8, the sub-pixels on the image display surface DS are shown. A sub-pixel is each of the partial pixels obtained by equally dividing each pixel constituting the image displayed in the image display system 1 along the vertical direction into m (where m is an integer of 2 or more), that is, n partial pixels arranged side by side in the horizontal direction in each pixel. Note that the sub-pixels may be each of the partial pixels obtained by equally dividing each pixel constituting the image displayed in the image display system 1 into m equal parts along a direction different from the vertical direction.

[0055] Either the left-eye image or the right-eye image is displayed in each sub-pixel. In FIG. 8, the left-eye image is indicated by the character "L", and the right-eye image is indicated by the character "R". In the following description, in the image display surface DS, the region occupied by the sub-pixels in which the left-eye image is displayed is also referred to as the left-image region, and the region occupied by the sub-pixels in which the right-eye image is displayed is also referred to as the right-image region.

[0056] In FIG. 8, in the regions D1, D2, D3, and D5 on the image display surface DS, the left-eye image is displayed, and the illumination light transmitted through the pixel is incident on the left eye EL. On the other hand, in the region D4, both the left-eye image and the right-eye image are displayed, and the right-eye image included in the region D4 is incident on the left eye EL.

[0057] In order to eliminate crosstalk, in this modification, as shown in FIG. 9, the arrangement of the left-eye image and the right-eye image is changed. In FIG. 8, the period in which the left-eye image and the right-eye image are arranged in the sub-pixels is such that the left-eye image and the right-eye image are each continuously arranged in only 4 sub-pixels, and the length of the period in which the left-eye image and the right-eye image are arranged in the sub-pixels is 8 sub-pixels.

[0058] In contrast, in FIG. 9, the length of the period in which the left-eye image and the right-eye image are arranged in sub-pixels is 7 sub-pixels. In the region to the left of region D8 here, only 3 consecutive sub-pixels of the left-eye image are arranged, and only 4 consecutive sub-pixels of the right-eye image are arranged. In the region including and to the right of region D8 compared to the region, only 4 consecutive sub-pixels of the left-eye image are arranged, and only 3 consecutive sub-pixels of the right-eye image are arranged. As a result, in regions D6, D7, D8, D9, and D10, the left-eye image is displayed and crosstalk does not occur. That is, only the left-eye image can be seen by the left eye EL. The period of the arrangement of the sub-pixels after the change is determined according to the distance between the observer H and the image display surface DS.

[0059] In FIG. 9, sub-pixels M1 to M5 show the sub-pixels removed from the arrangement of the sub-pixels in FIG. 8 for the purpose of explanation, and those sub-pixels M1 to M5 are not actually arranged.

[0060] The image display system according to this modification example is referred to as image display system 1a, and the image display device is referred to as image display device 10a. The image display device 10a includes a control device 4a as a control device. FIG. 10 is a diagram showing an example of the functional configuration of the control device 4a according to this modification example. The control device 4a includes a control unit 40a and a storage unit 41. The control unit 40a includes a reading unit 401, an image generation unit 402, an illumination arrangement surface control unit 403, an image display surface control unit 404a, and a position information acquisition unit 405a. Here, when comparing the control device 4a (FIG. 10) according to this modification example with the control device 4 (FIG. 7) according to the embodiment, the image display surface control unit 404a and the position information acquisition unit 405a are different in the control unit 40a. Here, the functions of the other components (the reading unit 401, the image generation unit 402, the illumination arrangement surface control unit 403, and the storage unit 41) are the same as those in the embodiment. The description of the same functions as in the embodiment is omitted, and in the second embodiment, the description will be centered on the parts different from the embodiment. Note that the same components as those in the above-described embodiments are denoted by the same reference numerals, and the description of the same components and operations is omitted.

[0061] The position information acquisition unit 405a acquires position information indicating the observer distance. The observer distance is the distance between at least one of the eyes of the observer H observing the image display surface DS and the image display surface DS. The image display surface control unit 404a controls each of the left image area and the right image area based on the observer distance indicated by the position information acquired by the position information acquisition unit 405a. Here, as described with reference to FIG. 9, the image display surface control unit 404a changes the period in which the left image area and the right image area are arranged on the image display surface DS based on the observer distance.

[0062] In the image display device 10a according to this modification, by including the position information acquisition unit 405a and the image display surface control unit 404a, each of the left image area and the right image area can be controlled based on the observer distance, so that crosstalk between the left-eye image and the right-eye image can be suppressed.

[0063] (Example) An example in the case where the image display system according to the above-described embodiment is used in an in-vehicle head-up display (HUD) will be described. FIG. 11 is a diagram showing an example of the configuration of the HUD 1b according to this example. The HUD 1b projects and displays an image SI1 on the windshield of an automobile as an example. The image SI1 is a stereoscopic image using a parallax barrier. The driver H1 drives while observing various information displayed as the image SI1 on the windshield.

[0064] The HUD 1b includes an image display device S1 and a camera C1. The configuration of the image display device S1 is the same as that of the image display device 10 (Fig. 7). That is, the image display device S1 includes a light source unit, a lenticular lens, an LCD, a control device, and the like. However, the image display device S1 is different from the image display device 10 in that the display unit is a front glass on which the image SI1 is projected. Further, the image display device S1 is different from the image display device 10 in that the control device changes the position of the image SI1 projected on the front glass according to the line of sight of the driver H1.

[0065] The camera C1 acquires the direction of the line of sight of the driver H1. The camera C1 is an eye-tracking camera. The control device provided in the image display device S1 changes the position of the image SI1 projected on the front glass according to the direction of the line of sight of the driver H1 acquired by the camera C1.

[0066] When the driver H1 observes the image SI1 projected on the front glass while sitting in the driver's seat, the driver H1 is recognized as, for example, the image SI1 being displayed at a position farther from himself than the position of the front glass. In Fig. 11, the distance VID1 indicates the virtual distance between the driver H1 and the image SI1 recognized by the driver H1. On the other hand, the depth SDD1 is the depth of the stereoscopic image of the image SI1. As described above, the distance VID1 is larger than the distance from the viewpoint of the driver H1 to the front glass corresponding to the display screen on which the image SI1 is displayed.

[0067] Note that, in the above-described embodiments, the image display device 10 or a part of the image display device 10a, for example, the control unit 40 or the control unit 40a may be realized by a computer. In that case, a program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize it. Here, the "computer system" refers to a computer system built in the image display device 10 or the image display device 10a and includes hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Furthermore, the "computer-readable recording medium" also includes a communication line such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, which holds the program dynamically for a short time, and a volatile memory inside a computer system serving as a server or a client in that case, which holds the program for a certain period of time. Also, the above program may be for realizing a part of the aforementioned functions, and furthermore, it may be realized in combination with a program already recorded in the computer system for realizing the aforementioned functions. Also, a part or all of the image display device 10 or the image display device 10a in the above-described embodiments may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the image display device 10 or the image display device 10a may be individually made into a processor, or a part or all of them may be integrated and made into a processor. Also, the method of integrating into an integrated circuit is not limited to LSI and may be realized by a dedicated circuit or a general-purpose processor. Further, when a technology for integrating into an integrated circuit that replaces LSI appears due to the progress of semiconductor technology, an integrated circuit using such technology may be used.

[0068] The above has described in detail an embodiment of the present invention with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of the present invention.

Explanation of Reference Signs

[0069] 10, 10a... Image display device, LS... Lighting arrangement surface, LB... Strip light source, LL... Lenticular lens, LU... Element lens, DS... Image display surface

Claims

1. An image display device that displays a stereoscopic image by a parallax barrier method, a transmissive image display surface on which images of left-eye image data and images of right-eye image data are alternately displayed, an imaging unit in which a plurality of optical members having a plurality of strip-shaped optical property patterns are arranged on a surface located on the back side of the image display surface, a plurality of strip-shaped light sources that are arranged adjacent to each other in the width direction of the illumination arrangement surface, which is a surface located on the back side of the imaging unit, and irradiate illumination light onto the image display surface, comprising: the slit region of the parallax barrier method is formed by an image obtained by imaging illumination light from the strip-shaped light source on the back side of the image display surface by the optical member included in the imaging unit, the plurality of strip-shaped light sources are arranged on the illumination arrangement surface such that images formed by the strip-shaped light sources that are arranged adjacent to each other in the width direction of the illumination arrangement surface and are separated by a predetermined number based on the parallax barrier method are at the same position, an image display device.

2. The parallax barrier method is a time-division parallax barrier method, an illumination arrangement surface control unit that changes the arrangement of a light-emitting region that generates the illumination light in the illumination arrangement surface by changing which of the plurality of strip-shaped light sources emits light, an image display surface control unit that controls the image display surface based on the left-eye image data and the right-eye image data, further comprising: the image display surface control unit controls, according to the arrangement of the slit region that changes according to the arrangement of the light-emitting region, each of a left image region on the image display surface where the image of the left-eye image data is displayed and a right image region on the image display surface where the image of the right-eye image data is displayed. The image display device according to claim 1.

3. a position information acquisition unit that acquires position information indicating an observer distance, which is the distance between at least one of the two eyes of an observer observing the image display surface and the image display surface, further comprising: the image display surface control unit controls each of the left image region and the right image region based on the observer distance indicated by the position information acquired by the position information acquisition unit. The image display device according to claim 2.

4. A distance D, which is the distance between the light source and the imaging unit, a distance d, which is the distance between the imaging unit and the back side of the image display surface, a slit width w, which is the width of the slit region, and a pitch Wl, which is the distance between the centers of adjacent optical members arranged in plurality in the imaging unit, satisfy a relationship represented by Expression (2) when the number of divisions of the time division is n. 【Number 1】 The image display device according to claim 2 or claim 3.

5. The arrangement of the light-emitting region that generates the illumination light in the illumination arrangement surface does not change with time. The image display device according to claim 1.

6. An image display device that displays a stereoscopic image by a parallax barrier method, A transmissive image display surface on which images of left-eye image data and images of right-eye image data are alternately displayed, An imaging unit in which a plurality of optical members having a plurality of strip-shaped optical property patterns are arranged on a surface located on the back side of the image display surface, A plurality of strip-shaped light sources that are arranged adjacent to each other in the width direction of the illumination arrangement surface on a surface that is the back side of the imaging unit and irradiate illumination light to the image display surface, Comprising: Among the plurality of strip-shaped light sources, among the plurality of strip-shaped light sources arranged adjacent to each other in the width direction of the illumination arrangement surface, every predetermined number of strip-shaped light sources based on the parallax barrier method are arranged on the illumination arrangement surface such that images obtained by imaging illumination light from the strip-shaped light sources by the optical members included in the imaging unit are at the same position. An image display method of the image display device, An illumination arrangement surface control step of emitting a light source corresponding to a light-emitting region that generates the illumination light in the illumination arrangement surface among the plurality of strip-shaped light sources, A slit region forming step of forming a slit region of the parallax barrier method by the image, An image display surface control step of controlling the image display surface based on the left-eye image data and the right-eye image data, An image display method having the above steps.

Images