JP2009081645A - Video image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video image display apparatus which can selectively switch a two-dimensional image and a three-dimensional image, and display a high definition image by a low cost. <P>SOLUTION: The video image display apparatus prepares: a display screen; a first light image modulation unit which forms a first image modulated according to a video image signal on the display screen according to the video image signal; a second light modulation unit which forms a second image modulated according to the video image signal; and a switching unit. The second light modulation unit selectively switches and displays the formed second image together with the first image formed on the display screen based on a switching state of the switching unit by the same configuration of the first image, or a different configuration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video display device capable of selectively switching between a two-dimensional image and a three-dimensional image on a display screen, and in particular, a video that can be provided at low cost even when the display screen is enlarged. The present invention relates to a display device.

In recent years, with the suspension of terrestrial analog TV (television) broadcasting scheduled in 2011, high-definition (for example, 1920 × 1080 pixels) high-definition broadcasting and high-quality terrestrial digital TV (television) that have already started. ) Large-screen direct-view video display devices that can receive broadcasts have become widespread.

Generally, a display panel used in a thin direct-view type video display device includes a PDP (Plasma).
There are display panels and liquid crystal panels, but the contrast (also called the contrast ratio) of the liquid crystal panel is about an order of magnitude worse than that of the PDP. On the other hand, PDP still has problems to be solved, such as insufficient brightness when white display is performed on the entire surface. In addition, thin direct-view type video display devices account for a large percentage of the total cost, but panel unit prices have fallen significantly due to excessive panel production due to large-scale capital investment by panel manufacturers. The price has fallen by more than 20% per year.

  For this reason, each set maker continues to develop high-value-added video display devices, and the panel resolution is compatible with high-definition high-definition (1920 × 1080 pixels) broadcasting from XGA (1024 × 768 pixels). The pillar of the product lineup has shifted to the model. Further, as a next step, development of a 3D video display device capable of displaying a 3D stereoscopic image (hereinafter referred to as “3D image”) is in full swing.

  As a three-dimensional display method for displaying this three-dimensional image (three-dimensional stereoscopic image), at the initial stage of development, a right-eye image (two-dimensional image) and a left-eye image (two-dimensional image) are used as one field of a video signal. A liquid crystal shutter glasses method is known in which the liquid crystal shutters are switched every time and the liquid crystal shutters incorporated in the glasses are synchronized in synchronization therewith. However, this method is very inconvenient in practical use because liquid crystal shutter glasses are essential. Further, since the focus adjustment with the naked eye is performed on the surface on which the two-dimensional image is displayed (hereinafter referred to as “display surface”), there is a physiological problem such as eye strain.

  Patent Document 1 is known as a three-dimensional display method for solving the above-described problems and a three-dimensional video display apparatus using the same.

Japanese Patent No. 3022558

  In the above-mentioned Patent Document 1, a two-dimensional image obtained by projecting a display target object on a plurality of display surfaces at different positions in the set depth direction from the viewer's line-of-sight direction (hereinafter, a two-dimensional image is simply “ A three-dimensional display method is disclosed in which the image is abbreviated as “image” and the brightness of the image is individually and independently controlled for each display surface to obtain a three-dimensional image with less discomfort. In the three-dimensional display method according to the present invention, for example, while keeping the overall luminance seen from the viewer constant, the display surface closer to the viewer increases the luminance of the image, and the display surface farther from the viewer Reduce the brightness of the image. As a result, the viewer feels that the three-dimensional image is located between the plurality of display surfaces even if the two-dimensional image is displayed due to physiological or psychological factors or illusions. It will be.

  Further, the above-mentioned Patent Document 1 discloses a plurality of examples of a 3D video display device using the 3D display method.

  For example, in the first embodiment of the three-dimensional video display device (FIG. 20 of Patent Document 1), a plurality of two-dimensional video display devices (for example, CRT, liquid crystal display, LED display, plasma display, FED display, DMD) are provided by a half mirror. An optical system that arranges images of a display, a projection display, a line drawing display, etc.) at different positions (display surfaces) in the depth direction is disclosed. However, in this 3D video display device, in order to obtain a large 3D image, there is a problem that the device becomes large (particularly, the device depth becomes long) and becomes expensive. Furthermore, since the half mirror is used, the light use efficiency is reduced, and the brightness of the apparatus is reduced.

  Further, the 3D video display apparatus of the second embodiment (FIG. 21 of Patent Document 1) includes a shutter element that transmits / blocks light in front of a plurality of projectors that project images, and each projector. A scattering plate that controls scattering / transmission or reflection / transmission is arranged at the image formation position of the projected image from the projector, and the scattering / transmission timing of the scattering plate and the transmission / blocking timing of the shutter element are driven in combination. An optical system for controlling the depth position of an image formed on a scattering plate in a time division manner is disclosed. However, in this 3D video display device, the device becomes larger (particularly, the device depth becomes longer) in order to obtain a large 3D image. Further, the scattering plate for controlling scattering / transmission or reflection / transmission becomes very expensive when the size is increased.

  Further, in the 3D video display device described in the third embodiment (FIG. 22 of Patent Document 1), an optical system for displaying a plurality of images inside the 3D video display device outside the 3D video display device. Is disclosed. However, it is difficult to design a lens optical system 183 that converts a plurality of images inside the 3D video display device to an external display surface of the 3D video display device. Similarly, it is not practical to perform the shape control of the varifocal mirror described in the fourth embodiment (FIG. 23 of Patent Document 1) with high accuracy because it is extremely difficult. Further, the embodiment described below (for example, FIG. 24 of Patent Document 1) is not only difficult to manufacture due to high technical hurdles, but also causes a cost increase in order to realize a three-dimensional video display device. Many are likely to be very expensive.

  The present invention has been made in view of the above-described problems, and a purpose thereof is a video that can selectively switch between a two-dimensional image and a three-dimensional image and can display a high-quality image at low cost. It is to provide a display device.

  In order to achieve the above object, according to the present invention, there is provided a display device, a first light modulation unit that forms a first image modulated according to a video signal on the display screen, and the display screen; A second light modulation unit that forms a second image modulated in accordance with the video signal; and a switching device, the second light modulation unit based on a switching state of the switching device, Provided is a video display device that selectively switches and displays the formed second image together with the first image formed on the display screen in the same form as the first image or in a different form. .

  According to the present invention, in the video display device described above, when the second image is displayed in the same form as the first image, the second image is displayed as the first image. When the second image is formed in the same position on the same surface and the second image is displayed in a form different from the first image, the second image is changed to the first image when viewed from the observation direction. It is preferable that the second image is formed at a position on the display surface having a different depth, or when the second image is displayed in the same form as the first image, the second image is the same as the first image. When the second image is displayed in a form different from the first image, the second image is enlarged with respect to the first image on the display surface. It is preferable to form. Alternatively, when the second image is displayed in a form different from the first image, the second image is formed at a position on the display surface having a depth different from that of the first image when viewed from the observation direction. In addition, it is preferable that the luminance level is displayed on the display surface different from that of the first image, or the second image is displayed with a definition lower than the definition of the first image. Here, when the video signal that is the basis of the first image and the second image is entirely dark, that is, when the information relating to the luminance of the video signal is lower than a predetermined value, the luminance level of the second image is set to the luminance of the first image. It is preferable to make it higher than the level. Further, when the video signal is generally bright, that is, when the information related to the luminance of the video signal is higher than a predetermined value, the luminance level of the second image is preferably made lower than the luminance level of the first image.

  Furthermore, according to the present invention, in the video display device described above, the first light modulation unit and the second light modulation unit can each modulate light for each pixel corresponding to a video signal. Further, it is preferable that the liquid crystal panel forming the second light modulation unit has a smaller display area than the liquid crystal panel forming the first light modulation unit. In addition, according to the present invention, the video display device described above further includes a light source, and in order from the light source, a liquid crystal panel that forms the second light modulation unit, and the first light modulation unit. The liquid crystal panel to be formed further includes a polarization conversion unit that converts light from the light source into a desired polarization component, and the second light modulation unit includes the polarization The magnified image forming unit that modulates the intensity of light from the conversion unit corresponding to the video signal, and that magnifies and projects a magnified image of the second image from the second light modulation unit, further projects Preferably, the projection lens apparatus includes a rotationally asymmetric mirror and a lens.

  According to the present invention, it is possible to provide a video display device capable of selectively switching between a two-dimensional image and a three-dimensional image and capable of displaying a high-quality image at low cost.

  Hereinafter, the best mode of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the element which has a common function is attached | subjected and shown, and the overlapping description is abbreviate | omitted about what was once demonstrated. In order to simplify the description, a case where a two-dimensional image is displayed on two display surfaces will be described, but the present invention is not limited to this. It goes without saying that the same effect as described later can be obtained with two or more display surfaces.

  Before describing the present embodiment, first, the principle of the three-dimensional display method disclosed in Patent Document 1 used for displaying a three-dimensional stereoscopic image in the video display device of the present embodiment will be described.

  FIG. 16 is a diagram for explaining the principle of the three-dimensional display method according to the present embodiment. The (a) figure is a perspective view, and the (b) figure is the figure seen from the front.

  As shown in FIG. 16, a plurality of display surfaces, for example, a first display surface 170a and a second display surface 160a, are set at different positions in the depth direction in front of the viewer 250 who views the video, Two images (two-dimensional images), that is, a first image 175 and a second image 155 are displayed on these display surfaces by using the video display device according to the present embodiment described later. The first display surface 170a corresponds to a display surface (image forming surface) of an image display liquid crystal panel 170 serving as a first light modulation unit described later, and the second display surface 160a is a second display surface described later. The display surface (image forming surface) of the liquid crystal panel 150 serving as the light modulation unit corresponds to the projected image surface (imaging surface) enlarged and projected by the projection lens device 10.

  The images (two-dimensional images) 175 and 155 displayed on the first display surface 170a and the second display surface 160a are three-dimensional objects to be presented to the viewer as described in FIG. It is an image obtained by projecting (display object) onto the display surfaces 170a and 160a from the viewing direction of both eyes of the viewer.

  As a method for generating images projected onto the display surfaces 170a and 160a, for example, a method using a two-dimensional image obtained by photographing a three-dimensional object with a camera from a line-of-sight direction, or a plurality of two-dimensional images obtained from different directions. Various methods such as a method of synthesizing from an image, a method of using computer graphic synthesis or modeling, and the like are mentioned. Note that the first video signal and the second video signal used in the video display device according to the present embodiment, which will be described later, are generated using any of these, and the first video signal is converted into the first image. Correspondingly, the second video signal often corresponds to the second image and has different signal components.

  On the other hand, in addition to the method disclosed in Patent Document 1, the present inventors display two types of images on a prototype video display device, change the sizes of the first image and the second image, It has also been confirmed that even though the content of the display screen is the same by changing the level of the luminance signal, it is displayed in a pseudo three-dimensional manner but can be visually recognized. Further, a more realistic three-dimensional image can be obtained by increasing the number of second images.

  As shown in FIG. 16B, the first image 175 and the second image 155 generated in this manner are respectively displayed on the first display surface 170a and the second display surface 160a. 250 are displayed so as to overlap each other when viewed from one point on the line connecting the right eye and the sagittarius. In the video display device according to the present embodiment to be described later, the size of the display surface is sufficiently large, such as about 27 to 100 inches, and the distance L between the first display surface 170a and the second display surface 160a is, for example, Since the optimum display interval can be set in accordance with the screen size from about 0 mm to about 50 mm, this condition can be sufficiently satisfied.

  Then, in order to make a three-dimensional image (three-dimensional stereoscopic image) sensed from two images (two-dimensional images), it is possible to view the three-dimensional object while keeping the overall luminance viewed from the viewer 250 constant. Change according to the depth position from the viewer. In order to display a two-dimensional image, two images (two-dimensional images) may be displayed.

  Next, an example of how to change the luminance will be described with reference to FIG. Here, for the sake of easy understanding, the higher luminance is shown darker.

  That is, for example, while keeping the overall luminance as viewed from the viewer 250 constant, the display surface closer to the viewer (here, the first display surface 170a) increases the luminance of the image and is farther from the viewer. The brightness of the image is lowered as the display surface (here, the second display surface 155a) is reached. Thereby, the viewer can display a plurality of display surfaces (here, the first display surface 170a and the second display) even if the two-dimensional image is displayed due to physiological or psychological factors or illusions. It will feel as if the three-dimensional image is located between the surfaces 155a). Furthermore, the definition of the first display surface may be higher than the definition of the second display surface.

  By using the three-dimensional display method described above, a plurality of images (two-dimensional images) are formed on a plurality of display surfaces having different depth positions as viewed from the viewer, thereby displaying a three-dimensional image (stereoscopic view). And a video display device capable of displaying an image capable of selectively switching between a two-dimensional image and a three-dimensional image by forming a plurality of images (two-dimensional images) on the same display surface. can get.

  Next, the video display apparatus according to the present embodiment will be described.

  The video display apparatus according to the present embodiment forms an optical image as an image in order to form a plurality of images (two-dimensional images) on a plurality of display surfaces having different depth positions as viewed from the viewer. At least two parts. Then, the first light modulation unit for modulating the incident light according to the first video signal to form the first image, and the light from the light source according to the second video signal One or a plurality of second light modulators to be arranged, and the light that is arranged on the light incident side of the first light modulator and is light-modulated by the second light modulator, An enlarged image forming unit for forming (mapping) a second image in the vicinity of the light incident side of the first light modulation unit. Then, the second light modulator is configured to display the formed second image together with the first image formed on the display screen based on the switching state of the switching device in the same form as the first image, or , Selectively display in different forms.

More specifically, when the second image is displayed in the same form as the first image, the second image is formed on the same position on the same surface when the first image is displayed, On the other hand, when the second image is displayed in a form different from the first image, the second image is formed at a position on the display surface having a depth different from that of the first image when viewed from the observation direction. Alternatively, when the second image is displayed in the same form as the first image, the second image is formed in the same size as the first image, while the second image is the first image. When displaying in a different form, the said 2nd image is expanded with respect to a 1st image, and it forms on a display surface. Furthermore, when the second image is displayed in a form different from that of the first image, the second image is formed at a position on the display surface that is different in depth from the first image when viewed from the observation direction. In addition, when the brightness level is displayed on the display surface different from the first image, or when the second image is displayed in a form different from the first image, the second image is The same effect can be obtained by displaying with a definition lower than the definition of one image.
Here, when the video signal that is the basis of the first image and the second image is entirely dark, that is, when the information relating to the luminance of the video signal is lower than a predetermined value, the luminance level of the second image is set to the luminance of the first image. It is preferable to make it higher than the level. Further, when the video signal is generally bright, that is, when the information related to the luminance of the video signal is higher than a predetermined value, the luminance level of the second image is preferably made lower than the luminance level of the first image. The information relating to the luminance of the video signal is, for example, an average luminance level (APL) for one screen (one frame or one field period) of the video signal. That is, in this embodiment, the APL of the input video signal is detected, and when this is lower than a predetermined threshold, the luminance level of the second image is set higher than the luminance level of the first image. The brightness or contrast of the second video signal corresponding to the second image is controlled. In addition, when the detected APL is higher than a predetermined threshold, the brightness of the second video signal corresponding to the second image or the brightness level of the second image is set to be lower than the luminance level of the second image. Control the contrast. Of course, the brightness or contrast of the first video signal corresponding to the first image may be controlled.
Furthermore, a luminance histogram for one screen (one frame or one field period) of the video signal may be used as the information relating to the luminance of the video signal. This luminance histogram divides the range from minimum to maximum luminance (gradation) into a plurality of areas in advance, and shows how many pixels belong to this divided gradation area in the period of one screen of the video signal. This is statistical information. For example, when the gradation expression range is 8 bits, that is, 0 to 255, it is divided into 32 gradations to obtain a total of 8 divided gradation areas. Then, a luminance histogram is obtained by counting the number of pixels belonging to the divided chairman area for each divided gradation area. In this luminance histogram, for example, the number of pixels belonging to the lowest divided gradation region is compared with a predetermined threshold value. When the number of pixels is larger than a predetermined threshold, it is determined that the image is entirely dark, and for example, the second video signal corresponding to the second image is controlled to be higher than the luminance level of the first image. On the other hand, when the number of pixels is smaller than a predetermined threshold value, or when the number of pixels belonging to the highest divided gradation area is higher than the predetermined threshold value, it is determined that the entire image is bright, for example, the second image The corresponding second video signal is controlled to be lower than the luminance level of the first image.
The above-described APL detection, luminance histogram generation, and control of the first or second video signal are executed by the control circuit 310 described later.

  Accordingly, the light of the second image formed by the magnified image forming unit is incident, and the light of the second image is optically modulated according to the first video signal to form the first image. In the present embodiment, as described above, the optical image (image) formed by the second light modulation unit is enlarged and projected (mapped) by the enlarged image forming unit to form the second image, and then by the switching device. As appropriate, the two-dimensional image and the three-dimensional image can be selectively switched. In addition, according to such a configuration, the screen size of the second light modulation unit can be made sufficiently smaller than the screen size of the first light modulation unit, so that a low-cost video display device and a three-dimensional video to which this is applied. A display device can be realized. In the following description, an optical image (image) formed by the second light modulator is referred to as an “original image” or a “second original image” in order to distinguish it from the enlarged and projected second image. And

FIG. 1 is a configuration diagram schematically showing an image display apparatus according to an embodiment of the present invention. In the following embodiments, a case where a transmissive liquid crystal panel is used as the second light modulator will be described as an example. In order to obtain a color image, color separation means for separating white light into RGB three primary color lights, three liquid crystal panels corresponding to each, and a composite prism for combining the color light images formed by the liquid crystal panels as a color image However, in FIG. 1, it is omitted for easy understanding, and each component is schematically shown by ignoring actual dimensions.

  In FIG. 1, an image display device 100 according to the present embodiment includes an image display liquid crystal panel 170 as a first light modulation unit for forming a first image, and a projection image forming device 200 for forming a second image. The Fresnel lens sheet 160 serving as a light direction conversion unit disposed in the vicinity of the incident side of the image display liquid crystal panel 170 and the first panel drive circuit 192 for driving the image display liquid crystal panel 170 to form a first image. And a second panel drive circuit 192 that drives the projection image forming apparatus 200 to form a second image.

  Depending on the set configuration of the video display device 100, a light diffusion sheet may be used instead of the Fresnel lens sheet 160.

  The projection image forming apparatus 200 is an image display liquid crystal panel (hereinafter simply referred to as “liquid crystal panel”) that performs color display as a first light modulation unit that modulates light (light modulation) in response to the first video signal 193. An enlarged image is projected from behind 170, and a second image is formed in the vicinity of the light incident side of the image display liquid crystal panel 170. That is, the second display surface 160 a described with reference to FIG. 16 is located in the vicinity of the light incident side of the image display liquid crystal panel 170. Then, the projection image forming apparatus 200 sequentially converts the light source 110 that emits substantially white light and the non-biased light emitted from the light source 110 into a polarization component in a desired direction toward the liquid crystal panel 170 for image display. A polarization conversion element 130 as a polarization conversion section to be aligned, a liquid crystal panel 150 as a second light modulation section that modulates light (white light) from the polarization conversion element 130 to form a second original image, and a liquid crystal panel In 150, the light beam (second original image) light-modulated corresponding to the second video signal 196 is enlarged and projected onto the image display liquid crystal panel 170 as the first light modulation unit, and the image display liquid crystal is displayed. The projection lens apparatus 10 is included as an enlarged image forming unit that forms the second image 155 on the second display surface 160a in the vicinity of the light incident side of the panel 170 (for example, in the vicinity of an incident side polarizing plate not shown).

  Note that the light flux from the projection lens device 10 is incident on the incident surface of the image display liquid crystal panel 170 substantially perpendicularly at the display surface position of the second display surface 160 a provided in the vicinity of the light incident side of the image display liquid crystal panel 170. A Fresnel lens sheet 160 is provided as a light direction conversion unit for conversion to be performed. Since the light flux from the projection lens device 10 is made to be a substantially parallel light flux by the Fresnel lens sheet 160, only light having an angle component with excellent contrast performance is incident on the image display panel, and as a result, video display is performed. The overall contrast performance of the device is greatly improved. On the other hand, it is possible to omit the Fresnel lens sheet 160 in order to realize cost reduction. In this case, however, it is necessary to add a diffusion sheet having a large light diffusion effect, so that the above-described effects cannot be obtained and the contrast is increased. The performance improvement effect cannot be obtained.

  The image display liquid crystal panel 170 serving as the first light modulation unit converts the image light of the projection image (second image 155) obtained by enlarging the second original image emitted from the projection image forming apparatus 200 into the first panel. Light modulation is performed again based on the first video signal 193 via the driving circuit 192 to form and emit a first image 175 as a main display image. Here, an active matrix driving TFT (Thin) used in a large-screen direct-view type liquid crystal TV having an aspect ratio of 16: 9, a pixel number of 1920 × 1080, and a screen size (diagonal dimension L1 of the screen display effective area) of about 27 to 60 inches. Film transistor) type liquid crystal panel. In general, the contrast ratio of a TFT type liquid crystal panel is about 1000: 1.

  Note that the liquid crystal panel 150 serving as the second light modulation unit and the liquid crystal panel 170 for image display serving as the first light modulation unit provided in the projection image forming apparatus 200 are arranged on the incident side and the liquid crystal panel 170 to obtain a high contrast image. Although a polarizing plate is provided on the emission side, illustration is omitted. In the case where the contrast performance is not important, the desired performance may be obtained even if one of the polarizing plates is omitted, so that all the polarizing plates are not necessarily required. In this case, it is possible to reduce the cost for the material cost of the omitted polarizing plate. Furthermore, since the projection image forming apparatus 200 of the present invention is provided with a polarization conversion unit that converts the uniform light emitted from the light source 110 into a polarization component in a desired direction and aligns it, the light utilization efficiency is normal. Extremely high compared to direct-view LCD TVs.

  The light source 110 includes, for example, a lamp 101 such as a high-intensity high-pressure mercury lamp that emits substantially white light, and a rotating paraboloid shape that covers the lamp 101 from behind and reflects the white light from the lamp 101 to convert it into parallel light. Reflector 102. In the present embodiment, the light emitted from the light source 110 irradiates the liquid crystal panel 150 as the second light modulator, which is sufficiently smaller than the image display liquid crystal panel 170, as will be described later. A discharge lamp such as a lamp can be used.

  The light emitted from the lamp 101 is reflected by, for example, a reflector 102 having a reflecting surface having a paraboloidal shape, is substantially parallel to the optical axis 115, and a substantially parallel light beam is emitted from the light source 110. The light emitted from the light source 110 enters the polarization conversion element 130.

  The polarization conversion element 130 aligns light with no bias emitted from the light source 110 with polarized light having a predetermined polarization direction. The light converted into the predetermined polarized light by the polarization conversion element 130 enters the liquid crystal panel 150.

  The liquid crystal panel 150 as the second light modulation unit performs light modulation based on the second video signal 196 via the second panel drive circuit 195 to form an optical image (second original image). Here, in order to reduce the price of the video display device, if the resolution is not so important, the resolution of the liquid crystal panel 150 may be lowered and a lower price panel may be used. For example, when the liquid crystal panel 170 has an aspect ratio of 16: 9 and an HD pixel count of 1920 × 1080, the WSVGA pixel count of 852 × 480 may be used for cost priority. On the other hand, as a screen size (diagonal dimension L2 of the screen display effective area), a TN type liquid crystal panel (transmission type liquid crystal panel) of a single matrix drive of about 0.4 to 1.3 inches is used.

  In general, the contrast ratio of a TN liquid crystal panel is about 700: 1, which is lower than that of a TFT type. However, in the present invention, the contrast ratio is the product of the contrast ratio of the liquid crystal panel 150 as the second light modulation unit and the contrast ratio of the image display liquid crystal panel 170 as the first light modulation unit. Another advantage is that the contrast ratio can be greatly improved while using a cheap panel.

  The second panel drive circuit 195 has a scaling function when the resolution of the liquid crystal panel 150 as the second light modulation unit is lower than that of the liquid crystal panel 170 as the first light modulation unit in order to reduce costs. In some cases, the second video signal 196 may be subjected to image processing such as scaling corresponding to the resolution of the liquid crystal panel 150. Thereafter, the liquid crystal panel 150 is driven to form a second original image (optical image). Further, the RGB signal supplied from the first panel drive circuit 192 to the image display liquid crystal panel 170 is supplied to the liquid crystal panel 150 (scaling processing corresponding to the resolution of the liquid crystal panel 150 if necessary). Also good.

  The projection lens device 10 as the enlarged image forming unit is configured to enlarge an image formed by the liquid crystal panel 150 and project the image onto the image display liquid crystal panel 170 as the first light modulation unit. At this time, when a conventional projection lens device is used, the depth dimension of the image display device increases. Therefore, although details will be described later in this embodiment, oblique projection is used to make the depth dimension as thin as possible.

  Since the projection lens device 10 of the present invention enlarges and projects the image of the liquid crystal panel 150 toward the image display liquid crystal panel 170 as the first light modulation section, it is necessary to satisfy the following conditions.

第２の光変調部としての液晶パネルは、最も小さいもので現在０．４８インチ（対角寸法）程度であり、０．４インチが限度と考えられている。そこで、液晶パネル１５０の画面サイズをＬ２＝０．４インチとし画像表示用液晶パネル１７０の画面サイズをＬ１＝６０インチとすればＬ１／Ｌ２＝１５０となる。Ｌ１／Ｌ２が１５０を越えると第１の光変調部としての画像表示用液晶パネル１７０に照射される明るさが暗くなるという問題が生じる。従って、Ｌ１／Ｌ２を１５０以下とすることが望ましい。下限は、液晶パネル１５０の画面サイズによるが、画像表示用液晶パネル１７０の画面サイズに近づけると、コストダウンにつながらないので、少なくともＬ１／Ｌ２＝１０以上とするのが望ましい。一般に、投写型映像表示装置に用いられる上限に近い画面サイズＬ２＝１．３インチのパネルを第２の光変調部としての液晶パネル１５０とし、第１の光変調部としての画像表示用液晶パネル１７０の画面サイズをＬ１＝２７インチとすればＬ１／Ｌ２＝２０程度となり、上記を満足することができる。

The liquid crystal panel as the second light modulation unit is the smallest and is currently about 0.48 inch (diagonal dimension), and 0.4 inch is considered the limit. Therefore, if the screen size of the liquid crystal panel 150 is L2 = 0.4 inches and the screen size of the image display liquid crystal panel 170 is L1 = 60 inches, L1 / L2 = 150. When L1 / L2 exceeds 150, there arises a problem that the brightness irradiated to the image display liquid crystal panel 170 as the first light modulation section becomes dark. Therefore, it is desirable that L1 / L2 be 150 or less. The lower limit depends on the screen size of the liquid crystal panel 150, but if it approaches the screen size of the image display liquid crystal panel 170, it does not lead to cost reduction, so it is desirable to set at least L1 / L2 = 10 or more. In general, a panel having a screen size L2 = 1.3 inches close to the upper limit used in a projection display apparatus is used as a liquid crystal panel 150 as a second light modulation section, and an image display liquid crystal panel as a first light modulation section. If the screen size of 170 is L1 = 27 inches, L1 / L2 = 20, which satisfies the above.

  The Fresnel lens sheet 160 is provided in the vicinity of the position of the second display surface 160a, and changes the light direction so that the oblique light from the projection lens device 10 is incident on the incident surface of the image display liquid crystal panel 170 substantially perpendicularly. Part. A refractive type that refracts and emits light having an incident angle within a predetermined value on one surface of the base material 161 constituting the Fresnel lens sheet 160 (here, the surface opposite to the image display liquid crystal panel 170 side). A plurality of Fresnel lenses 162 and a plurality of total reflection type Fresnel lenses 167 that totally reflect and emit light having an incident angle of a predetermined value or more are formed concentrically. Then, the light from the projection lens device 10 is refracted or totally reflected according to the incident angle by the refraction type Fresnel lens 162 and the total reflection type Fresnel lens 167, and is incident substantially perpendicularly on the incident surface of the image display liquid crystal panel 170. (Details will be described later).

  As described above, in the present embodiment, the liquid crystal panel 150 having a small size is used, light is modulated (light modulation, light intensity modulation) in accordance with the second video signal, and an image (second original image) is obtained. Image) is magnified and projected by the projection lens device 10 toward the image display liquid crystal panel 170 as the first light modulation unit, and the first image is displayed near the light incident side of the image display liquid crystal panel 170 (for example, near the incident side polarizing plate). The second image 155 is formed, and the light beam incident on the liquid crystal panel 170 is light-modulated again (the first image is formed) corresponding to the second video signal, so that the image can be viewed through the liquid crystal panel 170. Two images (second image and first image) having different depth positions as viewed from the user can be displayed simultaneously instead of time division. However, the stereoscopic display is not sufficient if the video display device 100 according to the present embodiment simply displays a plurality of images having different depth positions as viewed from the viewer. Therefore, the three-dimensional display method disclosed in Patent Document 1 is applied. That is, for example, the luminance is changed according to the depth position from the viewer of the three-dimensional object while keeping the overall luminance seen from the viewer 250 constant. As a specific example, for example, while keeping the overall luminance as viewed from the viewer 250 constant, the display surface closer to the viewer (here, the first display surface 170a) is increased in brightness of the image. The brightness of the image is lowered as the display surface is farther from the viewer (here, the second display surface 155a).

  In order to perform the control described above, when the video display device 100 is applied to a 3D video display device 300 that can select 2D video display or 3D video display, the 3D video display device 300 displays video. In addition to the device 100, a switching device 311 for switching display selection is provided together with the control circuit 310, so that the user can freely switch, for example. Note that the switching device 311 has at least “two-dimensional display” and “three-dimensional display” states (that is, switch switching states).

  The control circuit 310 includes a first panel drive circuit 192 that drives the image display liquid crystal panel 170 serving as the first light modulation unit, and a second panel drive circuit that drives the liquid crystal panel 150 serving as the second light modulation unit. For 195, control is performed so that a luminance difference is generated between the first image and the second image. For example, the first panel driving circuit 192 is controlled to increase the luminance, and the second panel driving circuit 195 is controlled to decrease the luminance. Needless to say, the luminance may be lowered only for the second panel drive circuit 195. Alternatively, the definition of the second image and the position of the display screen may be changed by adjusting the position of the projection lens device 10 as the enlarged image forming unit in accordance with the state of the switching device 311.

  Of course, the control circuit 310 is not limited to this. For example, as shown in FIG. 17, the 3D image display apparatus 300A includes a control circuit 310A instead of the control circuit 310, inputs a video signal 191 to the control circuit 310A, and performs predetermined signal processing in the control circuit 310A. The first video signal (for the first light modulation unit) and the second video signal (for the second light modulation unit) having a luminance difference are generated, and the generated first video signal 193 ′ and the second video signal (for the second light modulation unit) are generated. Two video signals 196 ′ may be supplied to the first panel drive circuit 192 and the second panel drive circuit 195, respectively.

  Note that the three-dimensional display method is not limited to the one described above, and it is obvious that various brightness control methods disclosed in Patent Document 1 may be adopted.

  Here, a part of the features other than the three-dimensional display of the video display device 100 of the present embodiment will be described.

  In the video display device 100 according to the present embodiment, as described above, the contrast ratio of the image is the product of the contrast ratio of the liquid crystal panel 150 and the contrast ratio of the image display liquid crystal panel 170. Can be improved.

  On the other hand, compared with the image display liquid crystal panel 170 as the first light modulation unit, the liquid crystal panel 150 as the second light modulation unit is sufficiently small, and in addition, the size of the light source 110 can be reduced. Accordingly, a projection device and a Fresnel lens sheet will be added compared to a method using an expensive liquid crystal panel of the same size as the image display liquid crystal panel 170, but when a low resolution liquid crystal panel can be used, The cost of the video display device can be reduced to 2/3 to 1/2.

  Further, the serviceability is greatly improved by making the liquid crystal panel 150 into a block with a synthetic prism (not shown) and replacing the light source 110 with each other.

  Further, unlike a normal direct-view type liquid crystal display device, it is not necessary to place a light source (usually a cold cathode ray tube or LED) as a heat source in the vicinity of the image display liquid crystal panel 170, and the design of the cooling structure is easy. It becomes.

  Although not described in detail above, even if one pixel of the liquid crystal panel 150 as the second light modulator is associated with a plurality of pixels of the image display liquid crystal panel 170 as the first light modulator, the reverse is also true. Further, a plurality of pixels of the liquid crystal panel 150 may correspond to one pixel of the image display liquid crystal panel 170, and the present invention is not limited to these. Needless to say, one pixel of the liquid crystal panel 170 for image display (one pixel includes a set of R pixel, G pixel, and 1B pixel) may correspond to one pixel of the liquid crystal panel 150.

  Moreover, although the high pressure mercury lamp was used as the light source, a white light LED or laser may be used. When the amount of light is insufficient with one LED or laser, an array of a plurality of LEDs or lasers may be used.

  In addition, a transmissive liquid crystal panel is used as a second light modulation unit that modulates a light beam from a light source corresponding to the second video signal. Instead, a reflective light modulation element such as a reflective liquid crystal panel is used. (LCOS: Liquid Crystal on Silicon) or a micro mirror device (DMD: Digital Micro Mirror Device) may be used.

Next, an embodiment of the projection lens device will be described. Here, in order to make the depth dimension of the image display device as thin as possible, the projection lens device described in Japanese Patent Application Laid-Open No. 2006-292900 filed by the inventors is applied.

  FIG. 2 is a cross-sectional view showing the basic optical system configuration of the projection lens apparatus in the video display device, and the optical system configuration is shown as a YZ cross section in the XYZ orthogonal coordinate system. Here, the origin of the XYZ orthogonal coordinate system is the center of the display screen of the liquid crystal panel 150, and the Z axis is parallel to the normal 8 of the image display liquid crystal panel 170. The Y axis is parallel to the short side of the display screen of the image display liquid crystal panel 170 and is equal to the vertical (up and down) direction of the image display liquid crystal panel 170. The X axis is parallel to the long side of the display screen of the image display liquid crystal panel 170 and is equal to the horizontal (left and right) direction of the image display liquid crystal panel 170. FIG. 3 is a perspective view of a projection lens device constituting the projection image forming apparatus, and FIG. 4 is a cross-sectional view of the projection lens in which the optical path in the projection lens device is omitted. In FIG. 2, the Fresnel lens sheet 160 as the light direction conversion unit is omitted for the sake of simplicity.

  As shown in FIG. 2, the projection lens device 10 includes a projection lens 2 arranged in order from the liquid crystal panel 150 side on the optical path from the liquid crystal panel 150 to the Fresnel lens sheet 160 and the image display liquid crystal panel 170, It includes a free-form surface mirror 4 as one reflection mirror and a plane reflection mirror 5 as a second reflection mirror.

  The second original image on the display screen of the liquid crystal panel 150 is projected by the projection lens 2 toward the image display liquid crystal panel 170 as the first light modulation unit. At this time, when projected linearly, a predetermined distance is required, and the depth dimension of the image display apparatus 100 becomes long. That is, the depth of the video display device 100 is increased. Therefore, the optical path from the projection lens 2 toward the image display liquid crystal panel 170 (for example, optical paths indicated by the light beams 21, 22, and 23) is turned back by the free-form curved mirror 4 and the plane reflection mirror 5 to reduce the depth of the video display device 100. Like to do. Further, a light beam 21 that exits from the center of the screen of the liquid crystal panel 150 and travels toward the screen center of the image display liquid crystal panel 170 (hereinafter referred to as “screen center light beam”) The depth of the image display apparatus 100 is reduced by vertical (generally, such projection is referred to as “oblique projection”).

  As is apparent from FIGS. 2 and 4, the projection lens 2 has a front group 12 composed of a plurality of refractive lenses having a rotationally symmetric surface shape, and a free-form surface having at least one surface rotationally asymmetric. The rear group 13 includes a lens (hereinafter referred to as a “free-form surface lens”).

  In FIG. 2, since the length of the projection lens 2 is long, the position of the liquid crystal panel 150 may be far from the direction of the normal 8 of the image display liquid crystal panel 170, and the depth may be increased. . However, here, as shown in FIG. 3, an optical path bending mirror 14 is arranged in the middle of the front group 12 arranged in parallel to the X axis (that is, the long side of the image display liquid crystal panel). The optical axis 9 (that is, the optical axis of the projection lens) is bent in the Z-axis direction (that is, the direction parallel to the normal 8 of the image display liquid crystal panel 170) to prevent an increase in depth. Of course, the present invention is not limited to this, and the optical path bending is performed to bend the optical path between the free-form mirror 4 and the rear group 13 of the projection lens 2 or between the front group 12 and the rear group 13 of the projection lens 2. A mirror may be arranged.

  In the present embodiment, as shown in FIG. 2, the center of the display screen of the liquid crystal panel 150 is disposed on the optical axis 9 of the projection lens 2. Accordingly, the screen center ray 21 that exits from the center of the display screen of the liquid crystal panel 150 and passes through the center of the entrance pupil of the projection lens 2 toward the screen center of the image display liquid crystal panel 170 travels along the optical axis of the projection lens. . The screen center light beam 21 is reflected at a point P2 on the reflection surface of the free-form surface mirror 4, and then reflected at a point P5 on the plane reflection mirror 5, to a point P8 at the center of the screen of the image display liquid crystal panel 170. The light is incident at a predetermined angle (θs) (that is, obliquely) with respect to the normal 8 of the incident surface of the image display liquid crystal panel.

  This means that the light beam that has passed along the optical axis 9 of the projection lens 2 is obliquely incident on the image display liquid crystal panel 170, and the optical axis of the projection lens 2 is substantially the same as that for image display. It is provided obliquely with respect to the liquid crystal panel 170. When incident obliquely on the image display liquid crystal panel 170 by such a method, various aberrations that are not rotationally symmetric with respect to the optical axis occur in addition to the so-called trapezoidal distortion in which the projected rectangular shape becomes a trapezoid. Therefore, in this embodiment, these are corrected by the rear group 13 of the projection lens 2 and the reflecting surface of the free-form curved mirror 4.

  In the cross section shown in FIG. 2, a light beam emitted from the lower end of the screen of the liquid crystal panel 150 through the center of the entrance pupil of the projection lens 2 and incident on the point P9 at the upper end of the screen of the liquid crystal panel for image display 170 corresponding thereto. Let it be a light beam 22. Also, a light ray that is emitted from the upper end of the screen of the liquid crystal panel 150 through the center of the entrance pupil of the projection lens 2 and incident on the point P7 at the lower end of the screen of the liquid crystal panel 170 for image display is referred to as a light beam 23. Referring to FIG. 2, the optical path length from the point P3 through the point P6 to the point P9 is longer than the optical path length from the point P1 through the point P4 to the point P7. This means that the image point P9 of the image display liquid crystal panel 170 is farther than the image point P7 when viewed from the projection lens 2. Therefore, an object point corresponding to the image point P9 of the image display liquid crystal panel 170 (a point on the display screen of the liquid crystal panel 150) is closer to the projection lens 2, and an object point corresponding to the image point P7 is more If it is at a point far from the projection lens 2, the tilt of the image plane can be corrected. For this purpose, the normal vector at the center of the display screen of the liquid crystal panel 150 is inclined with respect to the optical axis of the projection lens 2. Specifically, the normal vector may be tilted so as to be directed toward the image display liquid crystal panel 170 in the YZ plane. A method of inclining the object plane to obtain an image plane inclined with respect to the optical axis is known. However, at an angle of view of a practical size, the image plane due to the inclination of the object plane is asymmetrically deformed with respect to the optical axis, and correction is difficult with a rotationally symmetric projection lens. Therefore, in the present embodiment, a rotationally asymmetric free-form surface that is not rotationally symmetric, ie, asymmetrical deformation of the image surface is used. For this reason, tilting the object plane can greatly reduce the distortion of the lower-order image plane, which is effective in assisting correction of aberrations by a free-form surface.

  Next, the operation of each optical element will be described. The projection lens 2 has an image display liquid crystal in which the front group 12 uses a second original image (a two-dimensional image obtained by light modulation) of the liquid crystal panel 150 as a second light modulation unit as a first light modulation unit. This is a main lens for enlarging and projecting on the panel 170 (to be precise, for example, forming an image in the vicinity of the incident side polarizing plate (not shown) in the vicinity of the incident side of the image display liquid crystal panel 170). Correct basic aberrations. The rear group 13 of the projection lens 2 includes a rotationally asymmetric free-form surface lens. Here, as is apparent from FIGS. 2, 3, and 4, the free-form surface lens is curved so as to face the concave with respect to the light emission direction. Then, the curvature of the portion of the free-form surface lens through which the light beam 23 toward the lower end of the image display liquid crystal panel 170 passes is made larger than the curvature of the portion through which the light beam 22 toward the upper end of the image display liquid crystal panel 170 passes. Yes.

  The free-form surface mirror 4 has a reflection surface having a rotationally asymmetric free-form surface. Here, the free-form surface mirror 4 is a rotationally asymmetric convex mirror that is curved so that a part thereof is convex toward the light reflection direction. Specifically, the curvature of the portion (P1) of the free-form curved mirror 4 that reflects the light that goes downward of the image display liquid crystal panel 170 is the curvature of the portion that reflects the light that goes upward of the image display liquid crystal panel 170 (P3). It is larger than the curvature. In other words, in the YZ section of the free-form surface mirror 4 (the screen longitudinal direction cross-section of the image display liquid crystal panel 170), the position P2 between the screen center ray 21 and the free-form surface mirror 4 is between P1 and P2. The dimension and the dimension between P3-P2 are made different so that the following equation is established.

また、自由曲面ミラー４の、画像表示用液晶パネル１７０の下方に向かう光を反射する部分（Ｐ１）が該光の反射方向に凸の形状を為し、画像表示用液晶パネル１７０の上方に向かう光を反射する部分（Ｐ３）が光の反射方向に凹の形状をなすようにしてもよい。

Further, a portion (P1) of the free-form curved mirror 4 that reflects light directed downward of the image display liquid crystal panel 170 has a convex shape in the reflection direction of the light and is directed upward of the image display liquid crystal panel 170. The portion (P3) that reflects light may have a concave shape in the light reflection direction.

  By the action of the free-form surface lens and the free-form surface mirror, correction of aberrations caused by oblique incidence is mainly performed. That is, in the present embodiment, the free-form curved mirror 4 mainly corrects trapezoidal distortion, and the rear group 13 of the projection lens 2 mainly corrects asymmetrical aberrations such as image plane distortion.

  As described above, in this embodiment, the projection lens 2 includes at least one rotationally asymmetric free-form surface lens, and the free-form surface mirror 4 forms a rotationally asymmetric free-form surface reflecting mirror. For this reason, it is possible to correct both trapezoidal distortion and aberration caused by oblique projection. As a result, the second original image light-modulated by the liquid crystal panel 150 based on the second video signal is enlarged and projected toward the image display liquid crystal panel, and this video light beam is again used as a pseudo secondary light source. Optical modulation is performed on the basis of the first video signal by the image display liquid crystal panel. From the viewing side, two images having different depth positions, that is, the second image 155 and the first image 175 can be observed at the same time instead of time division.

  Further, as these two images (second image and first image), two-dimensional images obtained by projecting the display object from the direction of the line of sight of the viewer are used. A two-dimensional image is generated as an enlarged image (projected image) of the liquid crystal panel 150 as the second light modulation unit, and the two-dimensional image on the near side as viewed from the other viewing side is an image as the first light modulation unit. By displaying on the display liquid crystal panel 170, a video display device capable of displaying a three-dimensional image can be obtained (for example, see the description of FIG. 16). At this time, it goes without saying that in order to increase the amount of information in the depth direction of the image and increase the definition of the three-dimensional image, it is sufficient to increase the number of display images of the projection image (two-dimensional image) as the second image. No.

  Next, the optical system of the projection lens apparatus 10 described above will be described with reference to FIGS. 5 and 6 and Tables 1 to 4 with specific numerical values exemplified.

  5 and 6 are ray diagrams of the optical system of the projection lens apparatus according to the present embodiment based on numerical examples. In the XYZ orthogonal coordinates described above, FIG. 5 shows a configuration in the YZ section, and FIG. 6 shows a configuration in the XZ section. In the projection lens 2, the optical path bending mirror 14 is disposed in the middle of the front group 12 as described in FIG. 3, but in FIG. 5, the optical path bending mirror 14 is omitted, and the optical system is arranged in the Z-axis direction. Expanded to show. The same applies to FIG. The optical path bending mirror has a certain degree of arbitrary installation position and angle, and does not affect the function of each optical element. Therefore, in the following description, the optical path bending mirror is omitted.

  The light emitted from the liquid crystal panel 150 displayed on the lower side of FIG. 5 first passes through the front group 12 including only lenses having only rotationally symmetric surfaces among the projection lenses 2 including a plurality of lenses. Then, the light passes through the rear group 13 including a rotationally asymmetric free-form surface lens and is reflected by the reflection surface of the free-form surface mirror 4. The reflected light is reflected by the flat reflecting mirror 5 and then enters the image display liquid crystal panel 170.

  Here, the front group 12 of the projection lens 2 is composed of a plurality of lenses each having a rotationally symmetric refracting surface, and four of the refracting surfaces are rotationally symmetric aspherical surfaces, and the others are spherical surfaces. It is. The rotationally symmetric aspherical surface used here is expressed by the following equation using a local cylindrical coordinate system for each surface.

ここで、ｒは光軸からの距離であり、Ｚはサグ量を表している。また、ｃは頂点での曲率、ｋは円錐定数、ＡからＪはｒのべき乗の項の係数である。

Here, r is the distance from the optical axis, and Z represents the sag amount. C is the curvature at the apex, k is the conic constant, and A to J are coefficients of the power of r.

  The free-form surface lens in the rear group 13 of the projection lens 2 uses a local orthogonal coordinate system (x, y, z) whose origin is the surface vertex of each surface, and is expressed by the following expression including X and Y polynomials. It is.

ここで、ＺはＸ、Ｙ軸に垂直な方向で自由曲面の形状のサグ量を表わしており、ｃは頂点での曲率、ｒはＸ、Ｙ軸の平面内での原点からの距離、ｋは円錐定数、Ｃ（ｍ、ｎ）は多項式の係数である。

Here, Z represents the sag amount of the shape of the free-form surface in the direction perpendicular to the X and Y axes, c is the curvature at the vertex, r is the distance from the origin in the plane of the X and Y axes, k Is a conic constant and C (m, n) is a coefficient of a polynomial.

  Table 1 shows numerical data of the optical system according to the present embodiment. In Table 1, S0 to S23 correspond to the codes S0 to S23 shown in FIG. Here, S0 indicates the display surface of the liquid crystal panel 150, that is, the object surface, and S23 indicates the reflection surface of the free-form curved mirror 4. Further, S24 is not shown in FIG. 4, but indicates an incident surface of the image display liquid crystal panel 170, that is, an image surface. In FIG. 4, the upper diagram shows a YZ sectional view of the projection lens 2 and the free-form surface mirror 4 according to this embodiment, and the lower diagram shows an XZ sectional view of the optical system.

  In Table 1, Rd is the radius of curvature of each surface. In FIG. 5, when the center of curvature is on the left side of the surface, it is expressed as a positive value, and in the opposite case, it is expressed as a negative value. In Table 1, TH is the inter-surface distance, and indicates the distance from the apex of the lens surface to the apex of the next lens surface. When a next lens surface is located on the left side in FIG. 5 with respect to a certain lens surface, the inter-surface distance is represented by a positive value, and when located on the right side, it is represented by a negative value. Further, in Table 1, S5, S6, S17, and S18 are rotationally symmetric aspherical surfaces. In Table 1, the surface number is indicated with an asterisk for easy understanding. Table 2 shows the coefficients of these four aspheric surfaces.

  In Table 1, S19 to S22 are the refractive surfaces of the free-form surface lens included in the rear group 13 of the projection lens 2, and S23 is the reflection surface of the free-form surface mirror 4 as described above, and the surface number. # Is shown next to Table 3 shows values of coefficients representing the shapes of these five free-form surfaces.

  In the present embodiment, the object surface that is the display screen of the video display element 11 is inclined by −1.163 degrees with respect to the optical axis of the projection lens 2. The inclination direction is expressed by a positive value in the direction in which the normal of the object surface rotates counterclockwise in the cross section of FIG. Therefore, in this embodiment, the object surface is inclined 1.163 degrees in the clockwise direction from the position perpendicular to the optical axis of the projection lens 2 in the cross section of FIG.

  The free-form surface mirror 4 in S23 has the origin of its local coordinates on the optical axis of the projection lens 2. Then, the normal line at the origin of the local coordinates of the free-form surface mirror 4, that is, the Z-axis is inclined by 29 degrees from a position parallel to the optical axis of the projection lens 2. As in the case of the object surface, the inclination direction is positive in the counterclockwise direction in the cross section of FIG. 5, and is therefore inclined counterclockwise. As a result, the screen center ray that has exited from the center of the screen of the liquid crystal panel 150 and traveled substantially along the optical axis of the projection lens 2 is reflected at S23 and then twice the tilt angle with respect to the optical axis of the projection lens 2. Proceed in a direction inclined by 58 degrees. Here, a direction that passes through the coordinate origin of S23 and is inclined twice the tilt angle of S23 with respect to the optical axis of the projection lens 2 is set as a new optical axis after reflection, and the subsequent surfaces are arranged on this optical axis. Shall. The surface spacing value −400 shown in S23 of Table 1 is that the next S24 is on the right side of S23, and the origin of the local coordinates is located at a distance of 400 mm along the optical axis after reflection. Is shown. The following planes are also arranged according to the same rules.

  Table 4 shows the state of inclination or decentering of the local coordinate system of each surface in this example. In Table 4, the inclination angle and the value of eccentricity are shown on the right side of the surface number, ADE is the magnitude of the inclination in the plane parallel to the cross section of FIG. 5, and the display rule is as shown above. is there. YDE is the magnitude of the eccentricity, and the eccentricity is set in a direction parallel to the cross section of FIG. 5 and perpendicular to the optical axis, and the downward eccentricity in the cross section of FIG. 5 is positive. In this embodiment, YDE is set to 0 (that is, no eccentricity).

  In the present embodiment, the inclinations and decentrations of all the optical elements are set in directions in a cross section parallel to the illustrated cross section.

  From Tables 1 and 3, it can be seen that the curvature c and the conic coefficient k are 0 in this embodiment. Trapezoidal distortion due to oblique incidence occurs extremely large in the direction of oblique incidence, and the amount of distortion is small in the direction perpendicular thereto. Therefore, a significantly different function is required between the direction of oblique incidence and the direction perpendicular thereto, and asymmetric aberrations are excellent by not using the curvature c and the conic coefficient k that function in all directions in rotational symmetry. Can be corrected.

上記表１〜４の数値は、液晶パネル１５０の画面上における１６×９の範囲の光変調された光学像（調光像）を画像表示用液晶パネル１７０の画面上における１４５２．８×８１７．２の大きさに投写する場合の一例である。そのときの図形歪を図７に示す。図７の縦方向は図５の上下方向であり、Ｙ軸の方向である。図７の横方向は画像表示用液晶パネル１７０上でＹ軸と直交する方向であり、図の長方形の中央が画面の中央である。図は画面の縦方向を４分割、横方向を８分割した直線の曲がりの状態を表示して図形歪の様子を示している。

The numerical values in the above-mentioned Tables 1 to 4 indicate that the light-modulated optical image (light control image) in the range of 16 × 9 on the screen of the liquid crystal panel 150 is 1452.8 × 817. This is an example of projecting to a size of 2. The graphic distortion at that time is shown in FIG. The vertical direction in FIG. 7 is the vertical direction in FIG. 5 and is the Y-axis direction. The horizontal direction in FIG. 7 is a direction perpendicular to the Y axis on the image display liquid crystal panel 170, and the center of the rectangle in the figure is the center of the screen. The figure shows the state of figure distortion by displaying the state of straight line bending in which the vertical direction of the screen is divided into four and the horizontal direction is divided into eight.

  A spot diagram of this numerical example is shown in FIG. In FIG. 8, the values of the X and Y coordinates on the display screen of the liquid crystal panel 150 are (8, 4.5), (0, 4.5), (4.8, 2.7), (8, 0). ), (0, 0), (4.8, -2.7), (8, -4.5), and (0, -4.5). Show. The unit is mm. The horizontal direction of each spot diagram is the X direction on the image display liquid crystal panel 170, and the vertical direction is the Y direction on the image display liquid crystal panel 170. Thus, both maintain good performance.

  The embodiment of the projection lens apparatus has been described above. In the above description, the light beam emitted from the projection lens 2 is reflected by the free-form curved mirror 4, and is further folded by the flat reflection mirror 5 so as to be directed to the image display liquid crystal panel 170. The present invention is not limited to this, and it goes without saying that the above-described plane reflecting mirror for folding may be omitted depending on the position of the projection lens.

  Next, an example of the Fresnel lens sheet 160 as the light direction conversion unit will be described.

  FIG. 9 is a schematic configuration diagram of a Fresnel lens sheet. FIG. 9A is a perspective configuration diagram when the Fresnel lens sheet is viewed from the projection device side, and FIG. 9B is a cross-sectional configuration along line GG. FIG.

  As shown in FIG. 9, the Fresnel lens sheet 160 is positioned corresponding to the refraction area 160 </ b> D corresponding to the approximate center of the screen of the image display liquid crystal panel 170 and the screen peripheral side of the image display liquid crystal panel 170. The total reflection region 160E is disposed so as to surround the refraction region 160D. In the refraction region 160D, a plurality of refraction type Fresnel lenses 162 are concentrically formed on the surface of the base material 161 opposite to the image display liquid crystal panel 170 side. The refractive Fresnel lens 162 has a function of refracting the light beam L61 having an incident angle projected from the projection lens device 10 within a predetermined value and emitting it vertically to the image display liquid crystal panel 170. In the total reflection region 160E, a plurality of total reflection type Fresnel lenses 167 are concentrically formed on the surface of the base material 161 opposite to the image display liquid crystal panel 170 side. The total reflection type Fresnel lens 167 has a function of totally reflecting the light beam L66 whose incident angle projected from the projection device 10 is equal to or greater than a predetermined value and emitting it vertically to the image display liquid crystal panel 170.

  As is well known, when the Fresnel lens sheet is composed only of a refractive Fresnel lens, the incident angle (angle formed with the normal line) incident on the Fresnel lens sheet increases and reflection at the incident surface of the Fresnel lens is likely to occur. Thus, the reflection loss greatly increases, and the image becomes dark at the peripheral edge of the screen. Therefore, in the present embodiment, the technique of WO2004 / 049059 is applied, and the total reflection is performed in the peripheral portion of the first image display liquid crystal panel 170 in a region where the incident angle from the projection device 10 is a predetermined value or more. Place the mold prism.

  First, the refractive Fresnel lens 162 in the refractive region 160D will be described.

  When the prism surfaces 163 of the respective refractive Fresnel lenses in an arbitrary cross section in the refractive region 160D of the Fresnel lens sheet 160 are joined, one curve (that is, an envelope) is obtained. A set of all obtained cross sections of the envelope forms one virtual plane. Hereinafter, this virtual surface is referred to as an “original surface”.

  The original surface associated with the refractive Fresnel lens constituting the refractive region 160D is generally a spherical surface in the projection display apparatus, but in this embodiment, the Fresnel lens sheet disclosed in Japanese Patent Application Laid-Open No. 2006-154719. Thus, the aspherical shape corresponding to the incident angle of the light beam incident on the image display liquid crystal panel 170 from the projection lens device 10 is adopted.

  At this time, the Fresnel angle of each prism surface is larger in the upper part than in the lower part in the refraction region 160D. As a result, light rays incident on the incident surface of the refractive region 160D of the Fresnel lens sheet 160 are incident substantially perpendicularly on the incident surface of the image display liquid crystal panel 170 over substantially the entire surface of the image display liquid crystal panel 170. Is converted to

  Next, a method of setting the surface shape of the plurality of concentric prism surfaces 163 (so-called Fresnel lens original surfaces) in the refraction type Fresnel lens 162 formed in the refraction region 160D described above will be described with reference to FIG. This will be described in detail with reference to FIG. As described above, the prism surface of the refractive Fresnel lens constituting the refractive region 160D is formed concentrically with a certain point (rotation axis) as the center. The original surface for determining the Fresnel angle of the prism surface of each refractive Fresnel lens (that is, the angle between the prism surface and the principal plane of the Fresnel lens sheet 160) is an aspherical shape. Here, as described above, the original surface is for determining the Fresnel angle of each prism surface, and refers to this lens surface when the entire refractive region 160D of the Fresnel lens sheet 160 is formed as one lens. That is, when setting the Fresnel angle of the prism surface of the refractive Fresnel lens, it is assumed that the entire refractive region 160D of the Fresnel lens sheet 160 has one lens characteristic, and the surface shape of the lens is the original surface. Set as. Then, a shape corresponding to each point of the refractive area 160D of the original surface (for example, a tangent line of the original surface at each point) is developed on the surface of the refractive area 160D. Thereby, the Fresnel angle of the prism surface at each point of the refraction area 160D is set. Therefore, a curve obtained by connecting the prism surfaces in the entire refractive area 160D of the Fresnel lens sheet according to the Fresnel angle, that is, an envelope including a set of all prism surfaces in the entire refractive area 160D of the Fresnel lens sheet is the original. Represents a surface. That is, the light refraction direction on the prism surface at each point in the refraction region 160D is determined by the shape of the original surface corresponding to each prism. The rotation axis is assumed to be orthogonal to the main plane (XY plane in FIG. 10) of the Fresnel lens sheet 160 (plane including the Z axis in the figure). The rotation axis includes a light ray 25 incident on the Fresnel lens sheet 160 and a point P15 where a surface 165 (a surface parallel to the YZ plane) that divides the Fresnel lens sheet 160 equally in the left and right directions intersects. That is, the rotation axis is an axis perpendicular to the main plane of the Fresnel lens sheet 160 (parallel to the normal 8 of the first image display liquid crystal panel 170), that is, the axis 166 in FIG.

  However, in the above description, since the incident angle of the incident light beam 25 varies depending on the position on the image display liquid crystal panel 170 (the angle with respect to the normal line of the incident surface), a plurality of axes 166 obtained as described above are also provided here. Will exist. Of the plurality of axes, the axis at the center is the rotation axis of the refractive Fresnel lens (that is, the center position of the concentric prisms constituting the refractive Fresnel lens).

  Subsequently, the Fresnel angle shape (angle) of each prism surface is obtained as follows. First, the angle of the prism for emitting the incident light to the image display liquid crystal panel 170 in the normal direction (the outgoing angle is 0 degree) while refracting the incident light on the prism surface of the refractive area 160D is set to each point of the refractive area 160D. Each of these is obtained by Snell's law. Next, the obtained prism surface is made continuous to form the original surface (aspheric surface) of the refractive Fresnel lens.

  The obtained original surface is approximated by the aspherical expression of Equation 3.

ここで、ＺはＺ軸に平行な面のサグ量、ｒは回転軸からの距離、ｃは頂点での曲率、ｋはコーニック定数（円錐定数）、ＡからＦはｒのべき乗の項の係数（非球面係数）である。

Here, Z is the sag amount of the plane parallel to the Z axis, r is the distance from the rotation axis, c is the curvature at the apex, k is the conic constant (conical constant), and A to F are the coefficients of the power of r (Aspherical coefficient).

  At this time, the approximate aspheric coefficient is compared with the actual light beam exit angle, and the position of the rotation axis and the aspheric coefficient are appropriately modified and / or appropriately adjusted so that the exit angle is approximately 0 degrees. Or make a change.

  In this way, depending on the required element, that is, the position of the rotation axis serving as the rotation center of the concentric prism portion constituting the refractive type Fresnel lens, and the aspherical coefficient of the original surface formed by the set of the prism surfaces. The refraction area 160D portion of the Fresnel lens sheet 160 is formed.

  FIG. 11 shows a schematic cross-sectional view of the Fresnel lens sheet 160 configured through the above process. FIG. 11 shows a cross section of the Fresnel lens sheet 160 that is parallel to the normal line of the Fresnel lens sheet 160 and includes the rotation axis.

  In FIG. 11, Z = f (r) is a polynomial that represents the aspherical original surface 164 associated with the refractive Fresnel lens in the refractive region 160 </ b> D of the Fresnel lens sheet 160, and is expressed by Equation 5. r corresponds to r in Equation 5 above and represents the distance from the rotation axis. The Fresnel angle θ1 of the prism surface 163 of the refractive Fresnel lens at the distance r1 (the angle between the principal plane of the Fresnel lens sheet 160 and the prism surface) is substantially equal to the inclination (tangent) of the original surface 164 at the distance r1. That is, when the aspherical expression of the original surface expressed by Equation 3 is Z = f (rn) and n is an integer of 1 or more, the Fresnel angle θn at each position of the refraction region 160D is expressed by Equation 6. .

よって、θ１ ＝ｆ(ｒ１ )´、θ２ ＝ｆ(ｒ２ )´、θ３ ＝ｆ(ｒ３ )´…となる。このように、屈折領域１６０Ｄの各位置のフレネル角θｎ は、非球面式の各位置（各距離ｒｎ）における微分値にほぼ対応している。このようにして、フレネルレンズシート１６０における屈折領域１６０Ｄの各位置のフレネル角θｎが設定される。

Therefore, θ1 = f (r1) ′, θ2 = f (r2) ′, θ3 = f (r3) ′,. As described above, the Fresnel angle θn at each position of the refraction region 160D substantially corresponds to the differential value at each position (each distance rn) of the aspherical expression. In this way, the Fresnel angle θn at each position of the refractive region 160D in the Fresnel lens sheet 160 is set.

  As described above, the light beam incident on the refractive region 160D of the Fresnel lens sheet 160 from the projection lens device 10 is refracted by each prism surface 163 of the refractive Fresnel lens. As described above, if the original surface 164 of the refractive Fresnel lens is formed into an aspherical shape corresponding to the incident angle of the incident light beam at each position of the refractive region 160D, each light beam refracted by each prism surface 163 is It becomes substantially parallel to the normal line of the Fresnel lens sheet 160. Here, as is apparent from FIG. 11, the Fresnel angle θ of the prism surface 163 located above the refraction area 160D of the Fresnel lens sheet 160 (that is, far from the rotation axis at the upper part in the vertical direction of the image display liquid crystal panel). Is larger than the Fresnel angle θ of the prism surface 163 located below the refractive region 160D of the Fresnel lens sheet 160 (that is, at the lower part in the longitudinal direction of the image display liquid crystal panel and close to the rotation axis). This is because, in the oblique projection in the present embodiment, the incident angle of the light beam is larger in the upper part of the image display liquid crystal panel than in the lower part of the image display liquid crystal panel.

  Next, the total reflection type Fresnel lens 167 in the total reflection region 160E will be described with reference to FIG.

  As shown in FIG. 11, the total reflection type Fresnel lens in the total reflection region 160 </ b> E includes a refractive surface 1671 and a total reflection surface 1672. The light beam L66 incident on the total reflection type Fresnel lens 167 in the total reflection region 160E is refracted by the refractive surface 1671 and travels toward the total reflection surface 1672. Then, it is totally reflected by the total reflection surface 1672, exits the Fresnel lens sheet 160, and enters the image display liquid crystal panel 170 perpendicularly.

  In order to emit incident light vertically to the image display liquid crystal panel 170, the angle α formed by the total reflection surface 1672 and the main plane is changed to a total reflection type Fresnel lens far from the total reflection type Fresnel lens close to the projection device 10. The angle β formed by the refracting surface 1671 and the main plane is conversely multiplied by a total reflection type Fresnel lens far from the total reflection type Fresnel lens close to the projection lens device 10. What is necessary is just to make it set large gradually. In this way, the light incident on the total reflection region can be emitted vertically to the image display liquid crystal panel 170.

  If the Fresnel lens sheet 160 is configured as described above, the incident angle of the light beam projected from the projection lens device 10 toward the image display liquid crystal panel 170 becomes approximately 0 degrees. Thus, it can be converted and emitted. Therefore, when the Fresnel lens sheet according to the present embodiment is used, the light beam from the projection lens device 10 is incident in parallel to the normal line of the image display liquid crystal panel 170 (that is, perpendicular to the image display liquid crystal panel 170). A high-contrast image can be displayed on the display liquid crystal panel 170.

  In the Fresnel lens sheet 160 described above, the refractive area and the total reflection area are provided on the incident side of the sheet, but the present invention is not limited to this. For example, as described in Japanese Patent Application Laid-Open No. 2005-91541 filed by the present inventors, a total reflection region is provided at the peripheral portion having an incident angle of a predetermined value or more on the incident side of the sheet, and the incident angle is formed on the exit side of the sheet However, a refractive region may be provided in the central portion that is less than or equal to a predetermined value.

  In the video display device shown in FIG. 1, the light amount distribution (also referred to as light intensity distribution or illuminance distribution) emitted from the light source 110 to the liquid crystal panel is not uniformed. There is a risk of uneven brightness in the image. Therefore, a projection image forming apparatus according to the first embodiment in which an integrator for uniformizing the light quantity distribution of illumination light from the light source is inserted between the light source and the liquid crystal panel will be described with reference to FIG.

  FIG. 12 is a schematic configuration diagram of the projection image forming apparatus according to the first embodiment.

  As shown in FIG. 12, the projection image forming apparatus of the present embodiment includes a light source 110, a first multi-lens element 121 and a second multi-lens element 122 that function as a multi-lens integrator 120 in a pair, The polarization conversion element 130 </ b> A, the superimposing lens 141, the field lens 145, the second liquid crystal panel 150, and the projection lens device 10 are included.

  The light source 110 includes a lamp 101 and a reflector 102. The lamp 101 is a white lamp of a high pressure mercury lamp. The reflector 102 has a reflecting surface having a parabolic shape, for example, which is disposed so as to cover the lamp 101 from the rear side, and has a circular or polygonal exit opening.

  The light emitted from the lamp 101 is reflected by the reflector 102 having a rotating parabolic reflecting surface, is substantially parallel to the optical axis 115, and a substantially parallel light beam is emitted from the light source 110. Light emitted from the light source 110 enters a multi-lens integrator.

  The multi-lens integrator 120 includes a first multi-lens element 121 and a second multi-lens element 122.

  The first multi-lens 121 has a plurality of rectangular shapes substantially similar to the liquid crystal panel 150 as the second light modulation unit and the image display liquid crystal panel 170 as the first light modulation unit when viewed from the direction of the optical axis 115. The lens cells are arranged in a matrix, and light incident from the light source is divided into a plurality of lights by a plurality of lens cells, and efficiently passes through the second multi-lens element 122 and the polarization conversion element 130A. To guide. That is, the first multi-lens element 121 is designed so that the lamp 101 and each lens cell of the second multi-lens element 122 are in an optically conjugate relationship.

  Similar to the first multi-lens element 121, the second multi-lens element 122 having a configuration in which a plurality of rectangular lens cells as viewed from the direction of the optical axis 115 are arranged in a matrix form each of the lens cells constituting the first multi-lens element 121. The shape of the lens cell of the first multi-lens element 121 corresponding to is projected (mapped) onto the liquid crystal panel 150 together with the superimposing lens 141.

  In this process, the light from the second multi-lens element 122 is aligned in a predetermined polarization direction by the polarization conversion element 130A. Then, the projected images by the lens cells of the first multi-lens element 121 are superimposed by the superimposing lens 141 and are made substantially parallel to the optical axis 115 by the field lens 145, and then superimposed on the liquid crystal panel 150. Adapted.

  Note that the second multi-lens element 122 and the condensing lens 141 disposed in the vicinity thereof are such that each lens cell of the first multi-lens element 121 and the liquid crystal panel 150 are optically an object and an image. Therefore, the light beam divided into a plurality of parts by the first multi-lens element 121 is liquid crystal panel by the second multi-lens element 122 and the superimposing lens 141. The light amount distribution on the liquid crystal panel 150 is made uniform by being superimposed on the image 150.

  Here, the polarization conversion action of the polarization conversion element 130A will be described with reference to FIG. FIG. 13 is a cross-sectional configuration diagram in which the polarization conversion element is cut along the long side of the liquid crystal panel including the optical axis.

  As shown in FIG. 13, the polarization conversion element 130 </ b> A includes a translucent member 31 that is a parallelogram column extending along a direction parallel to the short side of the second liquid crystal panel 150. In parallel with the orthogonal plane, a plurality of arrays are arranged in a direction parallel to the long side of the liquid crystal panel 150, and a polarizing beam splitter film (alternatively at the interface between the adjacent translucent members 31 arranged in an array. Hereinafter, abbreviated as “PBS film”) 32 and a reflective film 33 are formed. In addition, a λ / 2 phase difference plate 34 is provided on the exit surface from which the light transmitted through the PBS film 32 passes through the opening 35 on the incident side of the polarization conversion element 130A. In addition, the polarization conversion element 130A is a surface formed by the optical axis 115 and the extending direction of the translucent member 51 having a parallelogram prism (the optical axis 115 is a plane. It is configured symmetrically with respect to S115.

  Of the light rays 37 incident on the opening 35 through the first multi-lens element 121 and the second multi-lens element 122 to the polarization conversion element 130A configured as described above, for example, S-polarized light is PBS film 32. , Reflected by the opposing reflecting mirror 33 and emitted as S-polarized light. The P-polarized light passes through the PBS film 32, is converted to S-polarized light by the λ / 2 phase difference plate 34 on the emission surface, and is emitted. A plurality of such basic polarization conversion units 30 are configured, and the polarization conversion element 130A emits the light with the polarization direction of the incident light aligned with light having a predetermined polarization direction (here, S-polarized light). When aligning P-polarized light, a λ / 2 phase difference plate 34 may be provided on the exit surface of S-polarized light.

  As described above, the liquid crystal panel 150 can be uniformly illuminated by the multi-lens integrator 120 including the first multi-lens element 121 and the second multi-lens element 122 that form a pair.

  In the first embodiment, a multi-lens integrator 120 including a pair of first multi-lens elements and second multi-lens elements is used as an integrator for uniformizing (homogenizing) illumination light. Next, a projection image forming apparatus according to a second embodiment using a rod type integrator which is a kind of integrator will be described with reference to FIG.

  The rod type integrator includes a light funnel and a rod lens. Here, a light funnel is used. A reflective liquid crystal panel is used as the liquid crystal panel. However, the present invention is not limited to this, and a rod lens may be used instead of the light funnel, and the configuration of the optical system is changed. An arranged DMD (Digital Micro Mirror Device) element or a transmissive liquid crystal panel may be used.

  FIG. 14 is a schematic configuration diagram of a projection image forming apparatus according to the second embodiment.

  As shown in FIG. 14, the projection image forming apparatus of the present embodiment includes a light source 110B, a light funnel 125 functioning as an integrator, a polarization conversion element 130B, a condensing lens 142, a field lens 146, and a polarizing plate 151. A polarizing beam splitter prism (hereinafter abbreviated as “PBS prism”) 152, a reflective liquid crystal panel 150 B, a polarizing plate 153, and the projection lens device 10.

  The light source 110 </ b> B includes a lamp 101 and a reflector 103. The lamp 101 is a white lamp of a high pressure mercury lamp. The reflector 103 has a spheroidal reflecting surface disposed so as to cover the lamp 101 from the rear side.

  The light emitted from the lamp 101 disposed at the first focal point of the reflector 103 is reflected by the reflector 103 having a spheroidal reflection surface, and is disposed near the second focal position of the reflector 103. Is incident on the incident surface 125a.

  That is, the reflector 103 functions as a condensing unit that condenses the light emitted from the lamp 101 onto the incident surface 125 a of the light funnel 125. Of course, as in the first embodiment, a reflecting parabolic reflecting mirror may be used as the reflector 103, and the light may be condensed on the incident surface 125a of the light funnel 125 by a condenser lens.

  The light funnel 125 is formed of a hollow light pipe (so-called light pipe) like a kaleidoscope, and has a function of making the incident light quantity uniform (uniform) by repeating total reflection a plurality of times. Here, a light pipe is used in which the area of the cross section perpendicular to the optical axis 115 gradually increases toward the emission side. However, a rod lens filled with contents may be used.

  The light incident on the light funnel 125 repeats total reflection on the side surface of the light funnel 125, and light at various angles is superimposed on the exit surface 125b, so that the light quantity distribution is uniform. In addition, since the cross-sectional shape of the light funnel 125 is larger on the emission side, the angle of the light beam emitted from the emission surface 125b is substantially parallel to the optical axis. The light emitted from the light funnel 125 enters the polarization conversion element 130B.

  The polarization conversion element 130B includes a PBS prism 41 having a PBS film 41a provided on the exit surface 125b of the light funnel 125, and a total reflection disposed on the side of the PBS prism 41 on which the S-polarized light reflected by the PBS film 41a is directed. It includes a total reflection prism 42 having a film 42a, and a λ / 2 phase difference plate 43 provided on an emission surface 41b from which P-polarized light transmitted through the PBS film 41a of the PBS prism 41 is emitted.

  Of the light having a uniform light quantity distribution incident on the PBS prism 41 of the polarization conversion element 130B from the light funnel 125, the S-polarized light (S-polarized light) is reflected by the PBS film 41a and is reflected by the total reflection prism 42. The light is incident, reflected by the total reflection film 42a, and emitted from the emission surface 42b of the total reflection prism. Further, P-polarized light (P-polarized light) incident on the PBS prism 41 is transmitted through the PBS film 41a, emitted from the emission surface 41b, and further converted to S-polarized light by the λ / 2 phase difference plate 43 and emitted. In this way, the non-biased light incident on the polarization conversion element 130B is aligned with the S-polarized light by the polarization conversion element 130B.

  In addition, since the light beam approximately parallel to the optical axis 115 is incident on the polarization conversion element 130B by the light funnel 125 spreading on the emission side, it can be efficiently polarized and separated by the PBS film 41a. The shape of the exit surface of the polarization conversion element 130B configured by the exit surface 41b and the exit surface 42b is substantially similar to that of the reflective liquid crystal panel 150B.

  The condenser lens 142 is a relay lens that maps the exit surface of the polarization conversion element 130B onto the reflective liquid crystal panel 150B.

  The S-polarized light emitted from the polarization conversion element 130B is condensed by the condensing lens 142, is made substantially parallel to the optical axis 116 by the field lens 146, passes through the polarizing plate 151, is reflected by the PBS prism 152, and is reflected liquid crystal. Incident on panel 150B.

  Since the dimming image formed by being modulated by the reflective liquid crystal panel 150B is P-polarized light, it is transmitted through the PBS prism 152, the contrast is increased by the polarizing plate 153, and the projection lens device 10 forms an image display liquid crystal panel. The projected image is enlarged.

  A video display apparatus according to Example 3 will be described with reference to FIG.

  The video display apparatus according to the present embodiment is different from the second embodiment in that a color wheel is disposed as a time-division color separation unit in the vicinity of the incident surface 125a of the light funnel 125. If a color wheel is used, a color image can be time-divisionally displayed (color sequential display) by an image display light modulation unit that performs monochromatic display (for example, monochrome display). Therefore, when performing color display, one pixel is composed of a set of color pixels (R pixel, G pixel, and B pixel). However, since monochrome display is performed with one pixel, the total number of pixels is small. Panels can be used. For this reason, cost reduction can be aimed at.

  FIG. 15 is a schematic configuration diagram of a video display apparatus according to the third embodiment.

  In FIG. 15, reference numeral 180 denotes a color wheel, and 170B denotes an image display liquid crystal panel that performs the above-described monochromatic display.

  The color wheel 180 includes, for example, an R light filter 181 that transmits R light (red light), a G light filter 182 that transmits G light (green light), and a B light filter 183 that transmits B light (blue light). The disk is formed at a predetermined ratio, has a rotation shaft (not shown) at the center thereof, and is rotated at a high speed by a drive unit (not shown). The color wheel 180 configured as described above is disposed between the light source 110 </ b> B and the light funnel 125 in the vicinity of the incident surface 125 a of the light funnel 125.

  The substantially white focused light emitted from the light source 110B is color-separated into R light, G light, and B light by the color wheel 180 in a time division manner.

  Then, the color light color-separated by the color wheel 180 is incident on the light funnel 125, the light quantity distribution is made uniform, and then converted into S-polarized light by the polarization conversion element 130B. Further, as the second light modulation unit, The image is modulated by the reflective liquid crystal panel in accordance with the second video signal, and the modulated image is enlarged and projected onto the image display liquid crystal panel 170B as the first light modulation unit by the projection lens device 10. The image display liquid crystal panel 170B forms a high-contrast image by performing modulation again according to the first video signal using the irradiated modulated enlarged image as a pseudo secondary light source. Through such a process, an R light image, a G light image, and a B light image are formed on the image display liquid crystal panel 170B in a time division manner, and are visually recognized as a color image.

  According to the present embodiment, it is possible to reduce the cost of the color direct-view image display device.

  In the above description, the reflective liquid crystal panel is used for the second light modulation unit. However, a DMD element in which micromirrors are two-dimensionally arranged may be used. Since the DMD element has a larger contrast ratio than the liquid crystal panel, it can be used more suitably.

  In the embodiment described above, polarizing plates are provided on the incident side and the emission side of the image display liquid crystal panel 170B. However, the screen size is large in the case of the direct view type video display device. Therefore, when a liquid crystal panel is used as the second light modulation unit, the first light modulation unit can be obtained by increasing the degree of polarization by using two polarizing plates disposed on the optical path of the liquid crystal panel, for example, two exit side polarizing plates. There is a possibility that the incident-side polarizing plate of the image display liquid crystal panel 170B may be deleted. In this case, the size of the polarizing plate attached to the liquid crystal panel is almost the same as that of the liquid crystal panel, and the incident side polarizing plate of the image display liquid crystal panel 170B is removed rather than the cost increase with two exit side polarizing plates. Therefore, the cost reduction of the video display device can be reduced. Further, when a DMD element is used as the second light modulation unit, the DMD element has a sufficiently larger contrast ratio than the liquid crystal panel. Therefore, the incident side of the image display liquid crystal panel 170B as the first light modulation unit is used. There is a possibility that the polarizing plate can be deleted.

The block diagram which showed typically the video display apparatus of one Embodiment by this invention. FIG. 3 is a cross-sectional view showing a basic optical system configuration of a projection lens device in an image display apparatus according to the present invention. The perspective view of the projection lens which comprises a projection lens apparatus. Sectional drawing of a projection lens. The light ray figure of the projection optical system in the YZ cross section concerning this embodiment. The light ray figure of the projection optical system in the XZ cross section concerning this embodiment. The figure showing the distortion performance of the projection optical system concerning this embodiment. The figure showing the spot performance of the projection optical system concerning this embodiment. The schematic block diagram of the Fresnel lens sheet concerning this embodiment. Explanatory drawing of the method of setting the prism surface shape which comprises the refractive type | mold Fresnel lens of the refraction | bending area | region 160D. The figure which shows the relationship between the prism surface in the refraction | bending area | region 160D, and an original surface. 1 is a schematic configuration diagram of a projection image forming apparatus according to Embodiment 1. FIG. FIG. 3 is a cross-sectional configuration diagram in which the polarization conversion element according to Example 1 is cut along the long side of the liquid crystal panel including the optical axis. FIG. 6 is a schematic configuration diagram of a projection image forming apparatus according to a second embodiment. FIG. 6 is a schematic configuration diagram of a video display device according to Embodiment 3. The figure for demonstrating the principle of the three-dimensional display method concerning this embodiment. The block diagram which showed typically the modification of the three-dimensional video display apparatus of one Embodiment by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Projection lens, 4 ... Free-form surface mirror, 5 ... Plane reflection mirror, 9 ... Optical axis, 10 ... Projection lens apparatus, 12 ... Front group, 13 ... Rear group, 14 ... Optical path bending mirror, 21 ... Screen center ray,
22, 23 ... light, 25 ... light, 30 ... polarization converter, 31 ... translucent member, 32 ... PBS film, 33 ... reflection film, 34 ... λ / 2 phase difference plate, 35 ... opening, 37 ... light 41 ... PBS prism, 41a ... PBS film, 41b ... outgoing surface, 42 ... total reflection prism, 42a ... total reflection film,
42b: exit surface, 43: λ / 2 phase difference plate, 101: lamp, 102: reflector, 103
Reflector 110 Light source 115 Optical axis S115 Optical axis plane 116 Optical axis 120
... multi-lens integrator, 121 ... first multi-lens element, 122 ... second multi-lens element, 125 ... light funnel, 125a ... incident surface, 125b ... exit surface, 1
30, 130A, 130B ... polarization conversion element, 141 ... superimposing lens, 142 ... condensing lens,
145 ... Field lens, 146 ... Field lens, 150 ... Liquid crystal panel, 150B
DESCRIPTION OF SYMBOLS ... Liquid crystal panel 151 ... Polarizing plate 152 ... PBS prism 153 ... Polarizing plate 155 ... Second image 160 ... Fresnel lens sheet 160a ... Second display surface 160D ... Refraction region 160E ... Total reflection type region , 161 ... Base material, 162 ... Refractive Fresnel lens, 163 ... Prism surface, 164 ... Original surface, 165 ... Surface that divides the Fresnel lens sheet vertically and horizontally equally, 166 ... Rotating shaft, 167 ... Reflective Fresnel lens, 1671 ... Refracting surface, 1672
... Total reflection surface, 170, 170B ... Liquid crystal panel for image display, 170a ... First display surface, 17
5 ... 1st image, 180 ... Color wheel, 181 ... R light filter, 182 ... G light filter, 183 ... B light filter, 191 ... Video signal, 192 ... 1st panel drive circuit, 193 ...
First video signal, 195... Second panel drive circuit, 196... Second video signal, 200... Projection image forming apparatus, 300, 300 A. Three-dimensional video display apparatus, 310, 310 A ... control circuit, 311. Device, L61 ... light, L66 ... light, 100 ... video display device.

Claims (14)

A display device,
A display screen;
A first light modulation unit for forming a first image modulated in accordance with a video signal on the display screen;
A second light modulator for forming a second image modulated in accordance with the video signal;
A switching device,
The second light modulation unit, based on the switching state of the switching device, together with the first image formed on the display screen, the formed second image in the same form as the first image, Alternatively, a video display device that selectively switches and displays in different forms.   In the video display device according to claim 1, when the second image is displayed in the same form as the first image, the second image is displayed on the same surface as the first image is displayed. In the case where the second image is displayed in a different form from the first image, on the other hand, the second image is viewed from the observation direction and the depth relative to the first image is formed. Are formed on positions on different display surfaces.   In the video display device according to claim 1, when the second image is displayed in the same form as the first image, the second image is formed in the same size as the first image. On the other hand, when the second image is displayed in a form different from the first image, the second image is enlarged with respect to the first image and formed on the display surface. Video display device.   In the video display device according to claim 1, when the second image is displayed in a form different from the first image, the second image is viewed from the observation direction with respect to the first image. A video display device, wherein the video display device is formed at a position on a display surface having a different depth and is displayed on the display surface with a luminance level different from that of the first image.   5. The video display device according to claim 4, wherein a luminance level of the second image is lower than that of the first image.   6. The video display device according to claim 5, wherein when the information about the luminance of the video signal is higher than a predetermined value, the luminance level of the second image is made lower than that of the first image. Video display device.   5. The video display device according to claim 4, wherein a brightness level of the second image is higher than that of the first image.   8. The video display device according to claim 7, wherein when the information related to the luminance of the video signal is lower than a predetermined value, the luminance level of the second image is set higher than that of the first image. Video display device.   2. The video display device according to claim 1, wherein when the second image is displayed in a form different from the first image, the second image is displayed with a definition lower than the definition of the first image. A video display device characterized by being displayed on the screen.   2. The video display device according to claim 1, wherein each of the first light modulation unit and the second light modulation unit is a liquid crystal panel capable of modulating light for each pixel corresponding to a video signal. A video display device characterized by the above.   11. The video display device according to claim 10, wherein the liquid crystal panel forming the second light modulation unit has a smaller display area than the liquid crystal panel forming the first light modulation unit. Video display device.   12. The video display device according to claim 11, further comprising a light source, and in order from the light source, a liquid crystal panel that forms the second light modulator, and a liquid crystal panel that forms the first light modulator. A video display device characterized by comprising:   The video display device according to claim 12, further comprising a polarization conversion unit that converts light from the light source into a desired polarization component, and the second light modulation unit includes the polarization A video display device characterized by modulating the intensity of light from a conversion unit in accordance with a video signal.   2. The video display device according to claim 1, wherein the magnified image forming unit that magnifies and projects a magnified image of the second image from the second light modulation unit further includes a projection lens device. The lens apparatus includes a rotationally asymmetric mirror and a lens.

Images