JP2007240965A - Three-dimensional display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-shaped, high-speed light-direction control back light having high light-using efficiency, and also, capable of corresponding to multi-view points, to provide a direct-vision three-dimensional display using the back light, to provide a projection optical system where a high-speed light-direction control can be performed, and to provide a projection type three-dimensional display using the projection optical system. <P>SOLUTION: The direct-vision type display is constituted with the combination of a back light system 15 having a three-dimensional linear space imaging optical system and a spatial light modulator type image display device 22, n-sheets of the directive image by n view-points integral photography are displayed at high speed while changing the light direction in time division. The projection type display includes a means for switching the direction of exit light from a screen in time division. The switching means comprises one or m image display devices 22 and an enlarging projection optical system (e.g., lens 5 of focal distance f<SB>2</SB>). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stereoscopic display, and more particularly, to a time-division or a combination of time-division and space-division, a direct-viewing stereoscopic display for directional image display integral photography, and a projection-type stereoscopic display. In the present specification, “IP” means “integral photography”.

  In recent years, as the interest in a three-dimensional display increases, a more realistic stereoscopic display system has been required. Among many proposed methods, unlike holograms, laser light is not required, display resolution is not required to be in the wavelength order of light, colorization is easy, glasses are not required, and a wide field of view is achieved. There is a multi-view type three-dimensional display method that has a high possibility of the above.

This is an integral photography (abbreviation: IP) that enables very realistic stereoscopic display by increasing the number of viewpoints from the basic two viewpoints (two-lens) to multiple viewpoints (multi-lens). ) Is a method using technology (for example, Non-Patent Documents 1 to 5).
Of the following documents, those other than Non-Patent Documents 1 to 5 are cited as references in the disclosure section of the invention described later, Non-Patent Document 6 is OCB, and Non-Patent Documents 7 to 10 are FLC. Non-Patent Documents 11 and 12 are DMDs, Non-Patent Document 13 is Lumisty, and Patent Document 1 is a document relating to a three-dimensional linear space imaging optical system.
Japanese Patent Application No. 2005-200969 (public number not yet issued) MGLippman ： Epreuves reversibles donnant la sensation du relief. J.de phys., 7,4th series (November 1908), 821-825 HEIves: Optical properties of a Lippman lenticulated sheet. J. Opt. Soc. Am., 21 (March 1931), 171-176 APSokolov: “Autostereoscopy and integral photography by Professor Lippman's method”, Izd.MGU, Moscow State University Press, 1911 CBBurckhardt and ETDoherty: Beaded plate recording of integral photographs. Appl. Opt., 8, No. 11 (November 1969), 2329-2331 RLDeMontebello: Wide-angle integral photography-The integram system. Proc. 1977 SPIE Annu. Tech. Conf., San Diego, Seminar 10, No. 120-08 (August 1977), Tech. Digest 73-91 Y. Yamaguchi, T. Miyashita and T. Uchida: SID'93 Digest, p.277-281 (1993) Meyer, RB: “Ferroelectric Liquid Crystals”: A Review. Mol. Cryst. & Liq. Cryst., 40, p.33 (1977) Meyer, RB, Lieb ▲ e ▼ rt, L. Strzelecki, L. and Keller, P .: “Ferroelectric Liquid Crystals”, J. Phys. (France), 36 pL 69 (1975) Clark, NA and Lagerwall, ST: “Submicrosecond Bistable Electro-Optic Switching in Liquid Crystals”, Appl. Phys. Lett., 36, p. 899 (1980) Clark, NA, Handschy, MA and Lagerwall, ST: “Ferroelectric Liquid Crystal Electro-Optics Using the Surface Stabilized Structure”, Mol. Cryst. & Liq. Cryst., 94, p. 213 (1983) RNThomas, J. Guldberg, HCNathanson and PRMalmberg: IEEE Transactions on Electron Devices, ED-22 (1975) PGSerafimovich, BHCheong, PSAhn, JKShin and SHKim: “DMD Illumination Using Diffractive Optical Elements”, SID 2005 Digest of technical papers Vol.36-I p.902-905 Okita et al .: Sumitomo Chemical 1991-I, p.37-48

  In the method using the IP technology, as the number of viewpoints is increased as described above, realistic stereoscopic display is possible. However, the number of pixels required for the display is increased correspondingly, which is very expensive. Become a thing. If the number of viewpoints is increased by assuming that the number of pixels is constant, the resolution of the display image in one direction is degraded by that amount (1 / n resolution for n viewpoints). This is because multi-viewpoint display is performed only by space division.

  Therefore, as a method of solving this problem, a method of displaying a multi-viewpoint directional image using time division can be considered. This is because a high-speed display is used to control the direction of light from the display (screen in the case of projection), and at a certain moment, a directional image of a certain viewpoint is displayed and switched at high speed to display one frame. This is a method of sequentially displaying multi-directional directional images within a time period. In this case, although the resolution is not deteriorated, an n-times high-speed display and a high-speed light direction control system are required for n viewpoints.

  In the case of the direct-view type, OCB (Non-Patent Document 6), FLC (Non-Patent Documents 7 to 10), etc. can be considered as a liquid crystal display for high-speed display. There is currently no backlight as a high-speed light direction control system that can be used. In the case of a projection system, as a high-speed image display device, there are OCB and FLC modes as LCD and LCOS types, and other DMD types (Non-Patent Documents 11 and 12) exist. There is currently no projection optical system capable of this.

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a high-speed light direction control backlight that is thin, has good light use efficiency, and can handle multiple viewpoints. A second object is to provide a projection optical system capable of high-speed light direction control for projection.
The technology described above relates to a method for realizing multi-view integral photography by changing space division to time division, but for the purpose of more realistic stereoscopic display, the number of viewpoints is as large as possible. In addition, it is necessary to increase the resolution. In this case, in the method using only the time division described above, the limit of the high-speed response characteristic of the image display device determines the number of viewpoints. Therefore, although the number of pixels increases, it is conceivable to use both the space division method and the time division method.

A third object of the present invention is an integral photography that uses the high-speed light direction control backlight of the first object, adopts a space division method for an image display, and uses both a time division method and a space division method. It is to provide a 3D display (direct view type) of the system.
The fourth purpose is a projection system version for the third purpose, which uses a plurality of optical engines or projectors in the projection optical system capable of high-speed light direction control, and uses both time division and space division. It is to provide an integral photography type stereoscopic display (projection type).

To achieve the above object, the present invention is as follows.
The present invention (1) is a backlight having a three-dimensional linear space imaging optical system (: claim 1).
The present invention (1-2) is a backlight system comprising a backlight having a three-dimensional linear spatial imaging optical system and means for controlling the direction of light emitted from the backlight ( : Claim 2).

  In the present invention (2), a spatial light modulator type image display device is combined with the backlight system of the present invention (1-2), and a directional image of n-view integral photography is optically divided in a time division manner. The three-dimensional display is characterized in that n sheets are displayed at a high speed by changing the direction of (3). Here, “at high speed” quantitatively means displaying 60n images per second, “n” is an integer of 2 or more, and “directivity” is synonymous with “direction” ( same as below).

According to the present invention (3), in the present invention (2), the image display device is combined with a space division method by integral photography to display n viewpoints by time division and m viewpoints by space division. A three-dimensional display characterized by: (Claim 4). Here, “m” is an integer of 2 or more (hereinafter the same).
The present invention (3-2) is the stereoscopic display according to the present invention (3), wherein the time division direction and the space division direction are substantially orthogonal to each other (specifically, the time division direction / space (Division direction orthogonal combination type integral photography stereoscopic display): (Claim 5).

The present invention (4) is a projection three-dimensional display characterized by having means for switching the direction of light emitted from the screen in a time division manner in the projection display.
According to the present invention (5), in the present invention (4), the switching means displays n directional images of n-view integral photography at a high speed by changing the direction of light in a time division manner. A projection three-dimensional display (specifically, a time-division sequential integral photography type projection three-dimensional display) comprising a single image display device and an enlarged projection optical system.

  According to the present invention (6), in the present invention (5), there are m instead of the one, and each of the m image display devices converts a directional image of n-view integral photography by time division. Three-dimensional display that displays n viewpoints by time division and m viewpoints by space division by changing the direction of light and displaying n images at high speed (more on both time division and space division in detail) Type sequential integral photography type projection stereoscopic display) (claim 8).

  According to the present invention, it is possible to obtain a high-speed light direction control backlight that is thin, has high light utilization efficiency, and can handle multiple viewpoints. Further, a projection optical system capable of high-speed light direction control can be obtained for projection. In addition, using the high-speed light direction control backlight and adopting the space division method for the image display display, an integral photography type stereoscopic display (direct view type) that uses both the time division method and the space division method is obtained. It is done. Further, an integral photography type stereoscopic display (projection type) using a plurality of optical engines or projectors in the projection optical system capable of high-speed light direction control and using both time division and space division is obtained.

[Direct view type]
An example of the three-dimensional linear space imaging optical system (Patent Document 1) of the present invention (1) to (1-2) is shown in FIG. (A) of the figure shows an optical system in which two lenses 3 having a focal length f are arranged at the same magnification, the optical axes 10 are aligned with each other, and are separated by a distance 2f, and (b) is an enlarged case. In this optical system, the lenses (first lens, second lens) 4 and 5 having the focal lengths f ₁ and f ₂ are arranged such that their optical axes 10 coincide with each other and the distance f ₁ + f _{2 is} separated. A solid grid located at a distance f to the left from the left lens 3 in FIG. 1A is an object grid 1 representing a three-dimensional coordinate with respect to an object, and is located at a distance f from the right lens 3 to the right. A certain three-dimensional grid is an imaging grid 2 representing three-dimensional coordinates for imaging (the same applies to FIG. 1B). This optical system reproduces the position and direction of light emitted from one point of the object grid 1 in the state where the optical axis is symmetrically converted to the imaging grid 2. Therefore, the position and direction of a light beam at an arbitrary point on the object grid 1 are completely coincident with each other when the symmetry is transformed with respect to the optical axis 10 in the position and direction of the light beam on the imaging grid 2.

Now, pay attention to one point A on the object grid 1 in FIG. Assume that the direction of the light beam incident on this point A is changed to the right and left with respect to the optical axis direction as shown in the figure. At a point A ′ on the imaging grid 2 (a point corresponding to the point A), the incident direction to the point A is symmetrically transformed with respect to the optical axis 10 and becomes the emission direction at the point A ′. As shown in the figure, the direction of the light beam changes from side to side with respect to the optical axis 10. If the incident angle of light with respect to the optical axis 10 to the point A is ± θ ₁ , the light emission angle from the point A ′ is − (± θ ₁ ).

Similarly, in the case of the enlargement shown in FIG. 1B, the incident angle of the light to the point B on the object grid 1 located at the distance f ₁ from the first lens 4 to the left is changed, and the optical axis direction is changed. When the light beam is changed to the left and right, the emitted light with respect to the optical axis 10 at the point B ′ (the point corresponding to the point B) on the imaging grid 2 located at the distance f2 to the right from the second lens 5 It will change symmetrically.
When the incident angle to the point B is ± θ ₂ , the emission angle is − (± θ ₃ ), and the relationship between θ ₂ and θ ₃ is expressed by the following equation.

In the case of a backlight, the image display device surface 6 shown in FIGS. 1A and 1B has only an opening, and the imaging surface 7 is an emission surface of the backlight. In the case of a rear or front projection system, the image display device surface 6 has a surface of a device such as LCD, LCOS, or DMD, and the imaging surface 7 has a screen surface.
From the above discussion, when the incident angle of the parallel light is changed on the image display device surface 6 shown in FIGS. 1A and 1B, the parallel light is also formed on the image plane 7 and is described by the equation (1). The direction of light changes depending on the relationship.

The three-dimensional linear spatial imaging optical system shown in FIG. 1 has a trapezoidal shape on the imaging plane 7 even if the image display device surface 6 is tilted at a very large angle (even if θ ₄ and θ ₅ are increased). This optical system is suitable for ultra-thin rear projection systems without any distortion.
When this characteristic is applied to a backlight system, a thin backlight system having a three-dimensional linear spatial imaging optical system is realized. This thin backlight system does not control the light output by a light guide plate or a diffusing plate like a normal backlight, but controls the light output by using image formation. , Very good characteristics can be obtained.

FIG. 2 shows an example of a three-dimensional linear spatial imaging optical system for a thin backlight system. This is a second lens function reflecting mirror 8 which is optically equivalent to the second lens 5 in FIG. 1, and uses only the portion where the light strikes. The magnification f ₂ / f ₁ and the inclination θ ₅ of the image display device surface 6 are set so that the image plane 7 is substantially parallel to the optical axis.
The relationship between the magnifications f ₂ / f ₁ and θ ₅ and θ ₆ in FIG. This relationship is similarly established in FIG.

Assuming that the surface of the image display device actually exists on the image display device surface 6 and considering the pixels, the aspect ratio that is the ratio of the vertical and horizontal pixels on the image display device changes on the imaging surface 7, but the back This problem does not exist when used for lights.
FIG. 3 shows an internal structure of a light direction control thin backlight system having a three-dimensional linear spatial imaging optical system. In FIG. 2, a prism sheet 9 is installed on the imaging surface 7 and the direction of the emitted light is variable around the normal direction of the backlight emitting surface. A lens 11 (: focal length f _D ) is installed on the image display device surface 6. The main plane of the lens 11 coincides with the image display device surface 6, and the center (node) of the lens 11 is located on the optical axis 10 of the three-dimensional linear space imaging system. As means for switching the direction of light, for example, a plurality of LEDs (ultra-high brightness LEDs) 12 are installed on the front focal plane 13 of the lens 11 installed on the image display device surface 6. Reference numeral 14 denotes an optical axis of the lens 11.

  Therefore, the light emitted from any one of the ultra-bright LEDs 12 becomes substantially parallel light by the lens 11 and enters the three-dimensional linear space imaging optical system. The direction of the parallel light is a direction of a straight line connecting the position of the LED 12 and the center (node) position of the lens 11. Therefore, when a plurality of LEDs 12 are installed in this order from the front side to the oblique rear side as shown in the figure, and light is emitted one by one in the same order as this installation order, the light enters the three-dimensional linear space imaging optical system. The direction of the parallel light changes as shown in the figure, and the direction of the emitted parallel light whose direction has been changed by the prism sheet 9 on the imaging surface 7 also changes as shown in the figure. As is clear from the figure, the direction of the emitted parallel light can be designed according to the installation position of the LED 12.

FIG. 4 shows a backlight (thin backlight or thin backlight system) 15 in which the structure of FIG. 3 is mounted in a housing. The exit surface 16 of the backlight 15 is drawn face down in FIG. 3, but is drawn face up in FIG.
When the LEDs 12 in the housing (not visible in FIG. 4) are made to emit light one by one, almost parallel light is emitted from the entire surface of the prism sheet 9 and changes from side to side with the normal direction of the prism sheet 9 as the center. To do.

  That is, the backlight 15 is a time-division light direction control backlight having a three-dimensional spatial imaging optical system. In order to use this for integral photography, it is necessary to add a condensing function to the emitted light. This is because each directional image visible region must be separated in order to eliminate crosstalk between directional images. Since the backlight 15 shown in FIG. 4 is intended for directional image display only in the left-right direction, a Fresnel cylindrical lens 17 is provided on the prism sheet 9 as shown in FIG. Place additional.

  Since the light emitted from the prism sheet 9 is substantially parallel light, it is collected in a substantially line shape on the focal plane 18 of the Fresnel cylindrical lens 17. However, since the size of the light emitting portion of the LED 12 (see FIG. 3) is not a point like a delta function but a finite size, this condensed line has a width. This is the width in the left-right direction in each of the directional image visible regions # 1 to # 9 shown in FIG. The control of the width can be designed by the size of the light emitting portion of the LED 12 (see FIG. 3), the size of the homogenizer of each LED lamp, and the like. The directional image visible regions # 1 to # 9 correspond to each of the nine ultra-high brightness LEDs 12 (see FIG. 3). When light is emitted sequentially one by one, the Fresnel cylindrical lens 17 serving as the backlight emission surface. The light emitted from the entire surface gathers in one corresponding area of the directional image visible areas # 1, # 2, # 3,..., # 9, and one area where the light gathers sequentially is # 1. , # 2, # 3,... # 9 (in order of visible region sequence 19).

  However, although the backlight 15 shown in FIG. 5 can control the light in the left and right direction, it remains parallel light in the vertical direction, so a high-speed image display liquid crystal display is mounted on the backlight 15. Even if it is installed, only one part of the front view is visible, and the top and bottom of the display are invisible because no light enters the eyes. Therefore, a film that diffuses light only in the vertical direction is required. Since the diffusion in the left-right direction causes crosstalk of each directional image, it is desirable that the diffusion film does not have a diffusion characteristic in the left-right direction. Although diffusion by a lenticular lens sheet is also conceivable, moire with the prism sheet 9 and the Fresnel cylindrical lens 17 is generated, which is not preferable. Therefore, as an ideal form, a unidirectional diffusion film (D-film) that diffuses light only in one direction is used as a prism for diffusing in the vertical direction by aligning the one direction (light diffusion direction) with the vertical direction in FIG. The form arrange | positioned on the sheet | seat 9 can be considered. As this D-film, Lumisty (Non-Patent Document 13) can be cited. An example in which this D-film is used as a vertical diffusion film is shown in FIG. 20 in the figure is a three-layer structure in which a Fresnel cylindrical lens 17 (see FIG. 5) is arranged on a prism sheet 9 (see FIG. 4), and the D-film is arranged thereon as a vertical diffusion film. It is a structural film. The time-division light direction control backlight shown in FIG. 6 not only allows the upper and lower sides of the display to be seen by the D-film, but also increases the upper and lower viewing angles. Further, this D-film also serves to eliminate moire of the prism sheet 9 of the backlight and the Fresnel cylindrical lens 17.

  Spatial light modulator type high-speed image display (OCB, FLC, etc.) on 20 in FIG. 6 (the Fresnel cylindrical lens 17 is laminated on the prism sheet 9 and the D-film is further laminated thereon) The liquid crystal display) corresponds to the stereoscopic display of the present invention (2). The super bright LEDs 12 (see FIG. 3) for selecting the directional image visible region (# 1 to # 9) in FIG. 6 are sequentially emitted one by one, and the corresponding directional images are sequentially displayed on the display. If the display is performed at high speed, a stereoscopic image can be seen by a person watching the display in the directional image visible region (# 1 to # 9). Furthermore, when the observer moves the line of sight within the directional image visible region (# 1 to # 9), a stereoscopic video change accompanying the movement is seen, so that a more realistic stereoscopic view can be felt. The above is the description of the backlight (or backlight system) of the present invention (1) and (1-2) and the stereoscopic display of the present invention (2).

  A stereoscopic display using the backlight system of the present invention does not require alignment with pixels required for a parallax barrier or a lenticular lens system as in the prior art, and is easy to manufacture. Furthermore, since there is no slit for absorbing light, such as a parallax barrier, the light utilization efficiency is good. In addition, since the number of viewpoints can be changed simply by changing the number and position of the super-bright LEDs, the degree of freedom in design is great.

Next, the stereoscopic display of the present invention (3) and (3-2) will be described.
The stereoscopic display can realize more realistic stereoscopic display when the number of viewpoints is large. The stereoscopic display of the present invention (2) using the backlight or the backlight system of the present invention (1) to (1-2) is a time-dividing directional (directional) image of n-view integral photography. The number of viewpoints n is determined by the limit of the response speed of the device of the high-speed display to be used. Therefore, in order to exceed the upper limit value of n only by this time division, the stereoscopic display of the present invention (3) and (3-2) uses both the time division method and the space division method.

  Now, in the case of time division n viewpoints and space division m viewpoints, the total number of viewpoints is n × m viewpoints. In this case, assuming that the number of pixels is constant, the resolution of the directional (directional) image is 1 / m. As an example, FIG. 7 shows a horizontal time division / vertical space division type IP-LCD (example: 9 horizontal viewpoints × 5 vertical viewpoints = total 45 viewpoints). The backlight system 15 of FIG. 7 is the same as that of FIG. 6 and functions to switch the directional image visible areas # 1 to # 9 in the horizontal direction at high speed in a time division manner.

  The space-divided vertical multi-lens LCD 21 (for example, five vertical viewpoints) installed on the backlight system 15 is a lenticular lens type IP display only in the vertical direction. Therefore, when the ultra-high brightness LED corresponding to one directional image visible region # 1 in the backlight system 15 emits light, the directional images in the vertical direction are respectively displayed in the regions a to elongate in the vertically elongated region # 1. 5 viewpoints are displayed simultaneously in e. When a directivity image corresponding to five vertical viewpoints corresponding to the areas a to e in the area # 2 is displayed in synchronization with the light emission of the LED corresponding to the area # 2 at the next moment, the areas a to # in the # 2 are displayed. Within e, the corresponding directional images can be seen. This process is repeated at high speed in the order of # 1 to # 9, and the display of # 1 to # 9 of the next frame is performed in the same manner to perform moving image stereoscopic display.

  In the example of FIG. 7, the IP for 45 viewpoints is realized with the number of pixels for 5 viewpoints, and the resolution of 9 times the time division is compared to the conventional IP that displays only 45 viewpoints by space division alone. Will be realized. Also, as in this example, one of the vertical and horizontal directions orthogonal to each other is set to space division (or time division), and the other is set to time division (or space division) (in the present invention (3-2)). Applicable) has an advantage that the time division method and the space division method can be used together with a simple structure.

  Next, FIG. 7A shows an example of horizontal space division (three viewpoints) and horizontal time division (three viewpoints) only for the structure of one pixel. The focal lengths of the lenticular lenses 31 to 34 are all the same f, the distance between the principal planes of the lenticular lenses 31 and 32 and 33 and 34 is f, the principal plane of the lenticular lenses 32 and 33, and the LCD pixel The pixel surfaces 51, 52, and 53 are installed in substantially the same plane. The number of super bright LEDs required when using time division and space division only in the horizontal direction (or vertical direction) is the same as the number of viewpoints to be displayed, that is, the number of time divisions × the number of space divisions (this example Then, 3 × 3 = 9).

  In one pixel of the LCD, there are three pixels 51, 52, 53 for three viewpoints of space division. Each of the pixel surfaces of these three pixels 51, 52, and 53 is divided into three regions, which are regions 41 to 43, 44 to 46, and 47 to 49 shown in the figure. Although the LCD device is not divided into the areas 41 to 43, the position where the LED light is condensed and passed is different. The same applies to the regions 44 to 46 and 47 to 49. Therefore, in the case of FIG. 7A, there are three pixels where the positions where the nine LEDs converge in the areas 41 to 49 (the area including the areas 41 to 43 to be condensed is the pixel 51, and the areas 44 to 46 are similarly condensed. Is the pixel 52, and similarly, the region where the condensing regions 47 to 49 are combined is the pixel 53). In driving, the three LEDs corresponding to the areas 41, 44, and 47 emit light simultaneously from the left, and the directional images corresponding to the respective areas are simultaneously displayed on the three spatially divided pixels of the LCD. At the next moment, the three LEDs corresponding to the regions 42, 45, and 48 are caused to emit light at the same time, and the directional images corresponding to the respective regions are simultaneously displayed by the three spatially divided pixels of the LCD. At the last moment, the three LEDs corresponding to the regions 43, 46, and 49 are caused to emit light at the same time, and the directional images corresponding to the respective regions are simultaneously displayed by the three spatially divided pixels of the LCD. If the above process is considered as one frame and a moving image is displayed, IP for nine viewpoints in the horizontal direction can be realized with the number of pixels for three viewpoints using a normal triple speed device.

  The method illustrated in FIG. 7A (a method in which a combination of space division and time division is applied in the same direction (horizontal and horizontal, or vertical and vertical)) is the method illustrated in FIG. 7 (space division and time division are orthogonal to each other). Compared to the direction (vertical and horizontal or horizontal and vertical), alignment of four lenticular lenses and ultra-bright LEDs equivalent to the number of time divisions × number of space divisions are necessary and more complicated. Although it has a simple structure, it is a powerful system for applications that require as many viewpoints as possible only in the horizontal direction, and for securing the number of viewpoints in one direction when the device response speed is not very high. .

This is the end of the description of the direct view type.
[Projection type]
Next, the projection stereoscopic display of the present invention (4) and (5) will be described. These apply a time division sequential integral photography system to a projection type, and an example is shown in FIG. In the figure, the developed state of the optical system constituting the projection stereoscopic display is shown. Ultra-high brightness LEDs 12 corresponding to the number of time division viewpoints are installed in each of five viewpoint areas A to E arranged in one direction (in this example, in the horizontal direction) in the same plane. .

The image display device 22, are installed in the main plane of the lens 4 of focal length f _1. The lens 4 has a two-lens configuration, and an image display device 22 exists between the two lenses. Is parallel to the surface and the LED12 of the installation area A~E ride plane of the image display device 22, the distance between these two surfaces is a _1. Among the regions A to E, the central region C is located on the optical axis of the lens 4.
The focal length f ₂ of the lens 5 projection system magnified imaging system is (invention (5), (corresponding to enlarged projection optical system referred to in 6)) in fact composed of a plurality of lenses. The optical axis of the lens 5 coincides with the optical axis of the lens 4, the principal planes of the lenses 4 and 5 are parallel to each other, and the distance between the principal planes is b ₁ (= a ₂ ). At this time, the relationship a _1, b _1, f ₁ becomes the following equation.

Fresnel lens 23 having a focal length f ₃ is present on the screen surface of the rear projection system. The optical axis of the Fresnel lens 23 coincides with the optical axis of the lens 5 at the focal length f ₂ , the principal planes of the lenses 5 and 23 are parallel to each other, and the distance between the principal planes is b ₂ (= a ₃ ). At this time, the relationship between a ₂ , b _{2 and} f _{2 is} as follows.

Now, paying attention to the expression (3), the images of the five ultra-high brightness LEDs 12 are formed on the main plane of the lens 5 having the focal length f ₂ by the action of the lens 4 having the focal length f ₁ . The imaged areas A ′ to E ′ are indicated by dotted circles. In the case of time division, only one of the five ultra-bright LEDs 12 emits light at a certain moment, so that the light is focused on only one of the areas A ′ to E ′, and the LED 12 An image is formed. It is assumed that the light emitting surface of the ultra-high brightness LED 12 used in this system is homogenized. Since the light condensed in any one of the regions A ′ to E ′ passes through the entire lens 4 having the focal length f ₁ , the image information displayed by the image display device 22 installed on the main plane of the lens 4. Have everything.

Next, paying attention to equation (4), the image information displayed by the image display device 22 is enlarged and formed on the main plane of the Fresnel lens 23 having the focal length f ₃ by the action of the lens 5 having the focal length f ₂ . As is clear from the figure, even if the LED 12 located in any of the five regions A to E emits light, the emitted light is displayed on the image display device on the main plane of the lens 4 having the focal length f _1. was the image information is through the LED imaging on the corresponding region to E ', the same position on the principal plane of the Fresnel lens 23 having a focal length f _3, capable of magnified images.

In the case of time division, only one LED 12 at a certain moment emits light in the order of A → B → C → D → E, and in synchronization with this light emission, the image display device 22 displays a corresponding directional (directional) image. Is displayed. The enlarged image forming positions of these directional images are on the main plane of the Fresnel lens 23 at the same position corresponding to all five LEDs 12.
Well, here, spaced a distance b ₃ to the right from the main plane of the Fresnel lens 23 having a focal length f _3, consider a virtual plane 25 to the main plane and extending parallel to the Fresnel lens 23, a _3, The relationship between b ₃ and f ₃ is as follows.

Equation (5) shows the function of forming the image of the LED 12 in the regions A ′ to E ′ on the main plane of the lens 5 having the focal length f ₂ on the virtual plane 25. The second imaging regions A ″ to E ″ of the LED 12 are indicated by dotted circles on the virtual plane 25.
The second image formation is also displayed on the screen surface by the image display device 22 in the same manner as the first image formation of the LED 12 formed in the regions A ′ to E ′ on the main plane of the lens 5 having the focal length f _2. It includes all of the image information enlarged and imaged on the main plane of the corresponding Fresnel lens 23. Regions A ″ to E ″ where the second image of the LED 12 is imaged on the virtual plane 25 become directivity (directional) image visible regions A ″ to E ″. Because, in any of the areas A '' to E '', all of the image information enlarged and imaged on the main plane of the Fresnel lens 23 is included, and therefore, when a human eye is placed in this area, the crystalline lens This is because the image information enlarged and formed on the main plane of the Fresnel lens 23 is formed on the retina by the action of.

  Next, driving of the system (stereoscopic display) shown in FIG. 8 will be described. Only the LED 12 in the area A emits light at the first moment, and in synchronization with this, the image display device 22 displays a directivity (directionality) image to be viewed in the directivity (directionality) image visible area A ″. Due to the above-mentioned optical system mechanism, the directivity (directionality) image visible in the visible area A ″ can be seen by the human eye as an enlarged image on the main plane of the Fresnel lens 23. It will be. At the moment when only the LED 12 in the region A emits light, nothing can be seen in the other regions B ″ to E ″.

  At the next moment, the LED 12 in the area A disappears and only the LED 12 in the area B emits light. In synchronism with this, the image display device has a directivity (direction) to be seen in the image visible area B '' ( (Direction) Display an image. Directivity (direction) (magnified) on the main plane of the Fresnel lens 23 for the human eye in the directivity (directional) image visible area B '' by the same optical mechanism as when the LED 12 emits light in the area A Gender) The image will be visible. Note that at the moment when only the LED 12 in the region B emits light, nothing can be seen in the other regions A ″, C ″ to E ″.

A similar process is performed for the LED 12 in region C at the next moment, the LED 12 in region D at the next moment, and the LED 12 in region E at the last moment. When displaying at about 60 frames per second as one frame of moving image stereoscopic video in the entire process for the LEDs 12 in the areas A to E, the moving image IP of 5 viewpoints on the large screen by the projection system can be viewed with only one image display device. Can do.
In FIG. 8, since the time-division IP only in the horizontal direction is specialized, a unidirectional diffusion film (D that performs diffusion only in the vertical direction (the direction perpendicular to the paper in FIG. 8) in order to widen the vertical viewing angle) (D -film) 24 is added to the exit surface of the Fresnel lens 23 which is the screen surface. The unidirectional diffusion film 24 functions even if it is composed of a lenticular lens, but in order to avoid moire with the Fresnel lens, it is desirable that the film does not have a structure such as a microlens structure (surface irregular shape). As a desirable example, the above-mentioned rumisty can be mentioned.

  The above is the description of the system shown in FIG. 8, but the direction of the time division viewpoint is not limited to the horizontal (left and right) direction, but can be the vertical (up and down) direction. Furthermore, if the super bright LED 12 is not arranged in a horizontal row or a vertical row, but as a two-dimensional array, the diffusion plate of the Fresnel lens 23 is taken (if the unidirectional diffusion film 24 is removed), the vertical and horizontal (up / down / left / right) The time-sharing viewpoint IP can be realized with the projection system.

  Next, the projection stereoscopic display of the present invention (6) will be described. This realizes a larger number of viewpoints by using both the time division viewpoint switching method and the space division method, and an example is shown in FIG. This is basically the same as the system illustrated in FIG. 8 in terms of the optical mechanism and the driving method, but a plurality of image display devices are driven simultaneously as a combination of not only time division but also space division. It differs from that of FIG. 8 in that it is displayed.

That is, in the example of FIG. 9, three image display devices 22 ₁ , 22 ₂ , and 22 ₃ are used, and each of them realizes time division IP with five viewpoints in the horizontal direction with the same optical mechanism and driving method as described in FIG. In order to display three horizontal viewpoints simultaneously in three spatial directions, IP for three horizontal viewpoints = total three horizontal viewpoints = 15 horizontal viewpoints in time division = three image display devices 22 _This is realized by ₁ , 22 ₂ and 22 ₃ .

Next, a driving method will be described. Only the LEDs 12 in the areas A, F and K emit light simultaneously at the first moment. At this time, the image display devices 22 ₁ , 22 ₂ , and 22 ₃ respectively display directivity (directional) images to be viewed in the directivity (directional) image visible areas A ″, F ″, and K ″. To do. By the same optical mechanism as described in FIG. 8, the human eye existing in the directivity (directional) image visible region A ″, F ″, K ″ has the main plane of the Fresnel lens 23. The directivity (directionality) image that is enlarged and formed on the top is seen separately in each region. Note that the moments when only the LEDs 12 in the regions A, F, and K emit light are the regions B '' to E '' and G '' to J in the other regions (other than the regions A '', F '', and K ''). '' 、 L '' ～ O ''can't see anything.

At the next moment, the LEDs 12 in the regions A, F, and K disappear, and only the LEDs 12 in the regions B, G, and L emit light, and in synchronization with this, the image display devices 22 ₁ , 22 ₂ , and 22 ₃ are respectively Directivity (Direction) Image The directivity (direction) image to be viewed in the visible region B ″, G ″, L ″ is displayed. By the same optical mechanism as when the LEDs 12 in the areas A, F, and K emit light, the human eyes existing in the directional (directional) image visible areas B '', G '', L '' A directional (directional) image enlarged and imaged on the main plane of the lens 23 can be seen. In addition, at the moment when only the LEDs 12 in the regions B, G, and L are emitting light, the regions A ″, C ″ to E ″, other regions (other than the regions B ″, G ″, and L ″) F ″, H ″ to J ″, K ″, M ″ to O ″ cannot see anything.

  The same process is performed for the LEDs 12 in the regions C, H, M at the next moment, the LEDs 12 in the regions D, I, N at the next moment, and the LEDs 12 in the regions E, J, O at the last moment. When displaying at about 60 frames per second as one frame of moving image stereoscopic video in the entire process of the above five steps, only the three image display devices 22 can see the moving image IP of 15 viewpoints in the horizontal direction of the large image by the projection system. Can do.

  In FIG. 9, since it is specialized in the time-division / space-division combined IP only in the horizontal direction, a unidirectional diffusion film (D-film) 24 that performs diffusion only in the vertical direction in order to widen the vertical viewing angle is provided. Further, it is added to the exit surface of the Fresnel lens 23 which is the screen surface. The unidirectional diffusion film 24 functions even if it is composed of a lenticular lens, but in order to avoid moire with the Fresnel lens, it is desirable that the film does not have a structure such as a microlens structure (surface irregular shape). As a desirable example, the above-mentioned rumisty can be mentioned.

The above is the description of the system shown in FIG. 9, but the direction of the time division viewpoint and the direction of the space division viewpoint are not limited to the horizontal (left and right) direction, and may be the vertical (up and down) direction, and the combinations are free. .
Note that the light diffusion direction of the unidirectional diffusion film 24 added to the Fresnel lens 23 may cause crosstalk of directivity (directionality) images unless designed to be perpendicular to the direction in which the viewpoints are arranged. When the viewpoints are arranged two-dimensionally vertically and horizontally, it is desirable not to add the unidirectional diffusion film 24 in order to avoid crosstalk.

  The description of the time division / space division combined IP system projection stereoscopic display according to the present invention (6) is now completed.

It is the schematic which shows the example of a three-dimensional linear space imaging optical system, (a) is a case of same magnification, (b) is a case of expansion. It is the schematic which shows the example of the three-dimensional linear space imaging optical system for thin-type backlight systems. It is the schematic which shows the example of the internal structure of the light control type backlight system which has a three-dimensional linear space imaging optical system. It is the schematic which shows the form which mounted the structure of FIG. 3 in the housing | casing. It is the schematic which shows the form which has arrange | positioned the Fresnel cylindrical lens on the prism sheet of the backlight of FIG. It is the schematic which shows the example of the backlight used for the three-dimensional display of this invention (2). It is the schematic which shows the example (example of this invention (3), (3-2); horizontal 9 viewpoints x vertical 5 viewpoints = total 45 viewpoints) of IP-LCD using horizontal time division and vertical space division combined. In this invention (3), it is the schematic which shows the system for 1 pixel of the example whose space division direction and time division direction are the same directions. It is the schematic which shows the example of the three-dimensional display of this invention (4), (5). It is the schematic which shows the example of the three-dimensional display of this invention (6).

Explanation of symbols

1 Object grid 2 Imaging grid 3 Lens (: Focal length f)
4 lenses (first lens: focal length f ₁ )
5 lens (second lens: focal length f ₂ )
6 Image display device surface 7 Imaging surface 8 Reflector for second lens function 9 Prism sheet
10 Optical axis (optical axis of 3D linear spatial imaging optical system)
11 Lens (Lens installed on the image display device surface: Focal length f _D )
12 LED (Super bright LED)
13 Front focal plane of lens (11)
14 Optical axis of lens (11)
15 Backlight (or backlight system; thin type)
16 Output surface of backlight (15)
17 Fresnel cylindrical lens
18 Focal plane of Fresnel cylindrical lens
19 Visible region sequence
20 Three-layer structure film (D-film for vertical diffusion + Fresnel cylindrical lens (17) + prism sheet (9))
21 Space division vertical multi-view LCD
22 Image display device
23 Fresnel lens
24 Unidirectional diffusion film (D-film)
25 Virtual plane
31, 32, 33, 34 Lenticular lens
41, 42, 43, 44, 45, 46, 47, 48, 49 area
51, 52, 53 pixels

Claims (8)

  A backlight having a three-dimensional linear spatial imaging optical system.   A backlight system comprising: a backlight having a three-dimensional linear space imaging optical system; and means for controlling the direction of light emitted from the backlight.   3. A spatial light modulator type image display device is combined with the backlight system according to claim 2, and a directional image of n-view integral photography is changed at high speed by changing the direction of light in a time division manner. A three-dimensional display characterized by displaying n sheets.   The stereoscopic display according to claim 3, wherein the image display device is combined with a space division method using integral photography to display n viewpoints by time division and m viewpoints by space division. .   The stereoscopic display according to claim 4, wherein the time division direction and the space division direction are substantially orthogonal to each other.   A projection display, comprising: means for switching the direction of light emitted from the screen in a time division manner.   The switching means includes a single image display device and an enlarged projection optical system that display n sheets of n-view integral photography directional images at high speed by changing the direction of light in a time division manner. The projection stereoscopic display according to claim 6.   In place of the one, the number is m, and each of the m image display devices displays n-view integral photography directional images at high speed by changing the direction of light in a time division manner. Accordingly, display of n viewpoints by time division and m viewpoints by space division are performed.

Images