JP2008139694A - Image display device and image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device and an image display method which are high in image quality and inexpensive. <P>SOLUTION: Light from a light source is polarized, the polarized light is separated and an image is formed by linear order by using a display element. Further, a middle image having a pixel arrangement possessed by the display element is formed and the light is deflected in a plurality of different areas on the exit side of a microlens array provided in a middle image surface. Thus, the image display device and the image display method which are high in image quality and inexpensive can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection type image display apparatus and an image display method using an optical deflection element.

In recent years, technologies relating to an optical deflection element and an image display apparatus using the same have been developed.
The light deflection element is an element in which a liquid crystal layer is provided between a pair of transparent substrates provided with a transparent electrode. The linearly polarized light is incident on this light deflection element. The liquid crystal layer uses a chiral smectic C layer ferroelectric liquid crystal capable of high-speed response, and directly shifts (light deflects) linearly polarized light incident on the liquid crystal layer to change the optical path. In other words, this is a technology that can shift light with a single element.

  Here, the transparent electrode is composed of a plurality of parallel line-shaped electrodes, and uniform light deflection is performed by giving a uniform electric field strength to the liquid crystal. It is known that high-quality image quality can be realized by the effect of increasing the number of pixels using this light deflection element in a projector (see, for example, Patent Document 1).

  On the other hand, an intermediate image of a spatial light modulation element is formed by a macro lens, a microlens array is placed at the position of the intermediate image, and the pixels are optically reduced. The reduced pixels are projected onto the screen by a projection lens. In addition, the number of pixels is increased by using an optical path shift element. Even when the optical path is shifted without reducing the pixels, the image quality can be further improved. Here, the optical path shift element is provided apart from the microlens. Further, the spatial light modulation element is mechanically driven to perform optical path shift (see, for example, Patent Document 2).

FIG. 20 is a diagram showing a conventional example of an image display device in which a transmissive liquid crystal spatial light modulator and a liquid crystal element + quartz plate are combined. In this technique, a deflection element is formed of a liquid crystal element and a quartz plate.
In the figure, 1 is a polarization direction control liquid crystal panel, 2 is a crystal plate, 3 is a transmissive liquid crystal spatial light modulator, 4 is a projection lens, 5 is a light source, and 61 and 62 are transmissive liquid crystal spatial light modulators 3. A frame memory having the same capacity as the number of pixels, 7 is a distributor, 8 is a synchronizing signal generator, 9 is a drive voltage generator for the polarization direction control liquid crystal panel 1, and 10 is a screen.

  The image display apparatus shown in FIG. 2 converts two orthogonal linearly polarized light beams emitted from a transmissive liquid crystal spatial light modulator (first linearly polarized light and second linearly polarized light) into a polarization direction by an image shift element. Correspondingly, the image is projected onto a different position on the observation surface or screen. The image formed on the entire pixel array (matrix) of the transmissive liquid crystal spatial light modulator is a one-frame image, which is divided into two fields (rows are divided into odd and even numbers), One linearly polarized light is made to correspond to the second linearly polarized light in even-numbered rows and alternately displayed in terms of time, and the number of pixels is apparently increased using a human afterimage. The transmissive liquid crystal spatial light modulation element and the deflection element do not correspond to the line sequential method. In addition, a technique is disclosed in which a microlens array is made to correspond to the pixel arrangement of the transmissive liquid crystal spatial light modulation element, the pixels are apparently reduced, and the overlap of pixel images on the screen is reduced (for example, Patent Documents). 3 and 4).

In addition, a technique is disclosed in which light emitted from an image display device in which pixels are arranged in a matrix is shifted by an image shift element divided into a plurality of regions to increase the apparent number of pixels and improve the resolution. ing.
The image display device is a method of displaying an image by scanning a video signal, and the image shift element shifts light in synchronization with this scanning. A plurality of regions of the image shift element are divided by line electrodes. There is a common electrode facing the line electrode, and a liquid crystal layer is provided between them. This changes the polarization direction of the linearly polarized light emitted from the pixel, and the light is deflected by the birefringence of a crystal plate adjacent to the element (see, for example, Patent Document 5).
JP 2003-0985502 A JP 2003-098595 A Japanese Patent No. 2813041 Japanese Patent No. 2939826 JP-A-8-194207

  However, the light deflection element corresponds to a spatial light modulation element that rewrites the screen all at once, and is used in a method that forms an image by scanning the entire screen in a line shape (referred to herein as a line sequential method). , Image quality may be degraded. This is because when the light deflection element tries to light deflect a certain frame (entire screen), the spatial light modulation element starts to form the next frame, that is, when the first frame is light deflected, the second second frame. This is because part of the light is also deflected.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image display apparatus and an image display method that can display a high-quality image on a display element that forms an image by line-sequential and can be manufactured at low cost.

  The invention according to claim 1 is a light source, a display element that forms an image by line sequential, a projection optical system that forms an intermediate image of a pixel array of the display element in an optical path of light from the display element, A microlens array provided at the position of the intermediate image and an optical deflection element provided on the emission side of the microlens array and deflecting light in a plurality of regions are provided.

  According to a second aspect of the present invention, in the image display device according to the first aspect, the microlens array and the light deflection element are integrated.

  According to a third aspect of the present invention, in the image display device according to the first or second aspect, the intermediate image is equal to or less than equal magnification.

  According to a fourth aspect of the present invention, a plurality of the microlens arrays according to any one of the first to third aspects are used.

  According to a fifth aspect of the present invention, in the image display device according to any one of the first to fourth aspects, the microlens array has a substantially flat portion around the apex.

  According to a sixth aspect of the invention, in the image display device according to any one of the first to fifth aspects, the three spatial light modulation elements are used.

  According to a seventh aspect of the present invention, in the image display device according to any one of the first to sixth aspects, the direction of light to be deflected is oblique with respect to a side of a rectangular pixel included in the display element. It is characterized by.

  According to the eighth aspect of the present invention, an image is formed line-sequentially by a display element using light from a light source, an intermediate image of a pixel array included in the display element is formed, and the intermediate image is provided at the position of the intermediate image The light emitted from the microlens array is deflected in a plurality of regions.

  According to the present invention, it is possible to provide an image display apparatus and an image display method that can display a high-quality image on a display element that forms an image by line-sequential and can be manufactured at low cost.

Next, embodiments of the present invention will be described.
FIG. 1A is a conceptual diagram showing an embodiment of an image display apparatus to which an image display method according to the present invention is applied, and FIG. 1B is an image display apparatus shown in FIG. FIG. 6 is an enlarged side view of the vicinity of the projection optical system.
The main configuration of the image display device is a light source 1, a polarization optical system 2, a display element 3, projection optical systems 4a to 4d, a microlens array 5a, a light deflection element 5b, and a control means 6, which are the projector casing. 7 and a screen 8 is arranged on the front surface (the upper side of FIG. 1A). Note that although a transmissive spatial light modulator is used as the display element, a reflective spatial light modulator may be used in the present invention. When the reflection type is used in this way, the configuration of the reflection type spatial light modulation element before and after is different, but the relationship between the microlens array and the light deflection element is the same. Examples of the spatial light modulator include those using liquid crystal or micromirrors.

That is, in FIG. 1A, a polarization optical system 2 including a polarization conversion element that polarizes light from the light source 1 in one direction is disposed on the optical path of the light source 1 that emits light in the Z-axis direction. A display element 3 is disposed on the light path on the emission side of the polarization optical system 2. If the display element is a display element that reacts only to one polarized light such as a liquid crystal, it is necessary to dispose the polarizing optical system 2 as described above. However, in the case of a display element using a micromirror device called MEMS, it is not always necessary to perform polarization. In addition, since the below-described light deflection element uses liquid crystal, it has dependence on linearly polarized light. Thus, for example, if the display element does not depend on polarization, before the non-polarized light is incident on the light deflecting element, the non-polarized light is made to be easily controlled so that the light deflecting element is not deflected or deflected. It is necessary to adjust to linearly polarized light.
A lens 4a of the projection optical system is disposed on the light path on the emission side of the display element 3, and a plane mirror 4b of the projection optical system is disposed on the light path on the light emission side of the lens 4a so as to be inclined by 45 ° with respect to the Z axis. Yes. The optical path of the reflected light of the plane mirror 4b is parallel to the X-axis direction. On the reflected optical path of the plane mirror 4b, the lens 4c of the projection optical system, the microlens array 5a, the light deflection element 5b, and the projection optical system. The lenses 4d are arranged in this order. A control signal line of the control means 6 is connected to the display element 3 and the light deflection element 5b.

Here, there are two types of image display devices, a front projector and a rear projector.
When the image display device is a front projector, the screen 8 may be a wall of a room or the like, and the screen 8 is not included in the constituent elements. However, when the image display device is a rear projector, the screen 8 is also included in the constituent elements.
The minimum configuration is shown whether the image display apparatus is a front projector or a rear projector.

  The light source 1 is generally a white lamp, for example, an ultra-high pressure mercury lamp. However, light sources such as light-emitting diodes and laser diodes are also being used, and are not limited to white lamps. A white lamp emits white light, which is unpolarized. This non-polarized light is aligned with the specific linearly polarized light by the polarization optical system 2. In order to increase the use efficiency of polarized light, a film using a polarization separation multilayer film is used, but in principle, only a specific polarized light can be extracted from non-polarized light even with a simple polarizing plate.

  Although not shown in FIG. 1A, as will be described later, white light is separated into three primary colors of red, green, and blue (hereinafter, R, G, and B) by a color separation element and a color separation optical system. Is done. If it remains white, it becomes a black and white image including a halftone.

  Here, the term “image shift element” is used in the conventional example, but in this embodiment, it is referred to as an optical deflection element.

  The projection optical systems 4a to 4d are composed of three lenses and one plane mirror. Here, it is simplified, the actual projection optical system is complicated, the number of optical elements is larger, and the shape is complicated. For example, the number of optical elements is about 10, and the shape may be an aspherical surface or a free curved surface instead of a spherical surface. In particular, when the image display device is a rear projector, a projection optical system that uses aspherical lenses and free-form surface mirrors in order to project an image on a screen without reducing the optical performance in reducing the thickness and size of the housing. Used. In such a projection optical system, an intermediate image may be formed between the optical elements.

In FIG. 1B, only five pixels 3a of the display element 3 are drawn. The lenses 4a to 4c are drawn as one lens. An intermediate image of the pixel 3a of the display element 3 is formed by the lenses 4a to 4c, and the microlens array 5a is installed at the position of the intermediate image. At this time, the pixels 3a and the microlenses 5aa of the microlens array 5a are set to correspond one-to-one.
That is, the size of the pixel 3a and the size of the microlens 5aa in the intermediate image are substantially equal.

  Here, the arrangement of the microlens array 5a at the position of the intermediate image of the pixel array is performed using, for example, a triaxial stage (adjustment with a high degree of freedom can be achieved by using a stage having a larger number of axes). In addition, a method may be used in which a jig with a microlens is aligned instead of the stage, and is bonded and fixed after adjustment.

Each microlens 5aa of the microlens array 5a condenses incident light on the region 10, for example. The light deflection element 5b is disposed adjacent to the emission side of the microlens array 5a. In FIG. 1B, there is a gap between the microlens array 5a and the light deflection element 5b, but it may be in close contact.
The object surface of the lens 4d is the position of the region 10 condensed by the microlens 5aa, and the image surface is a screen (not shown). If the light deflection element 5b is not driven, a pixel array 141 with a gap is displayed on the screen at this time as shown in FIG. That is, the pixel 143 is optically reduced.

  By forming an intermediate image in the projection optical system in this way, the light deflection element can be incorporated into the projection optical system. Further, by using the microlens array adjacent to the light deflection element, the step of providing the microlens according to the pixel arrangement of the spatial light modulation element can be omitted, and the cost can be reduced.

  In the present embodiment, since the microlens array 5a and the spatial light modulation element 3 are separated from each other, the step of manufacturing the microlens array 5a monolithically in the pixel array, or the microlens array 5a in the pixel array with high accuracy. The bonding step can be omitted, and the cost can be reduced.

  The control means 6 shown in FIG. 1A generates a signal synchronized with an image signal input to the display element 2 and a liquid crystal driving voltage for the light polarizing element 5b.

Details of the display element 3 are shown in FIGS.
FIG. 2A is a diagram of the display element 3 viewed from the front (optical axis), and FIG. 2B is an explanatory diagram thereof.
In the drawing, the number of pixel arrays is thinned out, but there is a 1024 × 728 pixel array by XGA (Extended Graphics Array). Also, in the figure, the pixels 3a are arranged without a gap, but in reality there is a gap (ineffective area) due to wiring to the pixel, etc., and the opening is determined by the ratio of the area of the part through which light passes and the area of the entire pixel. Rate is determined. The pixel 3a is, for example, a liquid crystal layer sandwiched between a pair of transparent electrodes. The pixel array is m × n (FIG. 2B).

  The image is formed by linear scanning. Scanning is performed in the row direction as indicated by a horizontal arrow in FIG. 2B (1 to m), proceeds to the first row, the second row,..., The nth row, returns to the first row, and the like. Repeated. This is one frame and one screen. In the line sequential method, scanning of the second row, the third row,..., The nth row is started before the first row is scanned. This is schematically shown in a timing chart as shown in FIG.

In FIG. 3, the horizontal axis is time, and the parallelogram showing one frame and two frames is drawn by superimposing signals in each row.
In FIG. 3, the signals in each row shown in FIG. 2B are represented by lines. After the start of the first row, the second scan is started. After the second row starts, the third row starts. The same applies to the nth row. When the scanning of the nth row is finished, this is one frame.
The scanning of the first row of 2 frames starts at the scanning time of the jth row of 1 frame. When one pixel in the pixel array is designated by (i, j) and a signal of the pixel is input in scanning, a voltage is applied to the liquid crystal layer according to the signal, and incident linearly polarized light is transmitted. Either changing the direction of vibration of the electric field is performed.

In an image display device using such a spatial light modulation element, a problem occurs when light deflection is performed on the entire surface of the element.
In FIG. 4, the timing chart shown in FIG. 3 and the timing chart of optical deflection are drawn together.
The signal on the rectangle indicates that light is deflected during that period. When the first frame is optically deflected, scanning starts for the second frame of the display element in the middle of the optical deflection of the first frame, so that the first image of the second frame is also deflected. As a result, the image quality is degraded.

(Description of optical deflection element)
FIGS. 5A and 5B show the configuration and function of the light deflection element used in the image display apparatus according to the present invention.
As shown in FIG. 5A, a liquid crystal 52 is sandwiched between a pair of translucent substrates 51. Although not shown, a transparent electrode and an alignment film are formed on the surface of the translucent substrate 51 on the liquid crystal 52 side. By applying a voltage in the y-axis direction of the illustrated coordinate (horizontal electric field) and reversing its polarity, the orientation of the liquid crystal molecules changes (FIGS. 5A and 5B).

When linearly polarized light having a vibration direction 53 of an electric field parallel to the y-axis as shown in the figure is incident on the light deflecting element, the light is deflected. On the contrary, when linearly polarized light having an electric field oscillation direction parallel to the x-axis (perpendicular to the paper surface) is incident on the light deflecting element, the light travels straight without being deflected.
Further, the material of the liquid crystal 52 used for the optical deflection element is preferably a ferroelectric liquid crystal that has good optical performance and can respond at high speed. For example, it is a chiral smectic C phase liquid crystal. However, it is not limited to this. The transparent electrode is generally ITO (Indium Tin Oxide), but is not limited to this, and may be ZnO or the like. Further, the optical deflection element shown in FIGS. 5A and 5B is divided into a plurality of regions.

FIG. 6 shows the optical deflection element divided into two parts, and FIG. 7 shows a timing chart of the optical deflection element shown in FIG.
The light deflection element shown in FIG. 6 is formed by patterning a transparent electrode in two regions on a single substrate. An electrode is provided so that a voltage can be independently applied to the two regions. In this example, there are two regions, but three or more regions may be used. When a voltage is applied to region 1, light deflection is performed only in region 1, and the same applies to region 2. It is also possible to deflect light by slightly shifting the timing, and it is possible to prevent the beginning of the second frame from being deflected at the time of the light deflection of the first frame (see FIG. 7).

The first frame is deflected in the first area until the middle of the first frame, then the remainder of the first frame is deflected in the second area, and the second frame that has already started is deflected in the first area. Repeat the operation. This operation is performed by the control means 6 shown in FIG.
Thus, by dividing the light deflection region of the light deflection element into a plurality, even when a line-sequential rewritable display element is used, light deflection is possible without degrading the image quality, and the number of pixels is increased. The resolution can be improved.

  In addition, when a conventional liquid crystal element and a light deflecting element using a combination of quartz plates are compared, the element can be simplified. Two translucent substrates having electrodes, two translucent substrates having electrodes with respect to the configuration of liquid crystals, and the configuration of liquid crystals.

FIGS. 8A and 8B show a case where light is deflected in the x-axis and y-axis, or in the horizontal and vertical directions.
It consists of two optical deflection elements 81 and 83 and a half-wave plate 82, and the half-wave plate 82 is between the two deflection elements 81 and 83. In FIG. 8A, the vibration direction of the electric field of the incident linearly polarized light is parallel to the x axis, and the first light deflecting element 81 deflects the linearly polarized light in two directions. On the other hand, in FIG. 8B, the oscillation direction of the electric field of the incident linearly polarized light is parallel to the y-axis, and the first light deflection element 81 does not deflect the linearly polarized light.

The linearly polarized light in these two directions is turned into a linearly polarized light whose vibration direction is parallel to the y-axis by rotating the vibration surface of the electric field by 90 ° with the half-wave plate 80. At this time, the slow axis of the half-wave plate 80 is installed rotated by 45 ° from the x-axis. Linearly polarized light having the electric field oscillation direction parallel to the y-axis is incident on the second light deflecting element 83, and is deflected in two directions and deflected in four directions.
Here, the deflection direction of the first optical deflection element 81 and the deflection direction of the second optical deflection element 83 are orthogonal to each other. In this way, it is possible to improve the number of pixels by four times.

  The amount of light deflection is preferably about ½ of the pixel pitch on the screen. The pixel pitch is a period of pixel arrangement in the spatial light modulator. When projected on the screen, it is multiplied by the projection magnification. This is adjusted by the thickness of the liquid crystal layer of the light deflection element, the refractive index, the voltage applied to the liquid crystal, and the like.

  An image obtained by pixel reduction is as shown in FIG. 14A. By deflecting the image in four directions, an image 142 as shown in FIG. 14B without a gap can be displayed. This is because the pixel 143 apparently increases by a factor of four due to the afterimage of a person and looks like 144. Further, since the pixels are reduced, the image quality can be improved.

  The surface of the microlens is preferably formed with a surface antireflection film.

An element in which the microlens array and the light deflection element are integrated is shown in FIG.
The light deflection element is formed by two glass substrates 90 and 91 on which a transparent electrode and an alignment film are formed, with the liquid crystal 92 sandwiched therebetween so that the transparent electrode and the alignment film face each other.
A feature of the present invention is that a microlens array 93 is provided on one glass substrate 90. A method of forming a microlens array on the glass surface of the deflecting element after forming the optical deflecting element is also conceivable. However, the method of forming the optical deflecting element using the substrate on which the microlens array of this embodiment is manufactured is also possible. However, production is easy.

  In addition, when the microlens array and the light deflection element are integrated, the microlens array substrate and the light polarization element substrate can be used together, and it is possible to reduce the number of members and manufacturing processes, thereby reducing the cost. It becomes possible.

  When the microlens is resinous, the microlens may be formed in an array on the glass surface by using, for example, an ink jet technique after the light deflection element is manufactured. When the size of the microlens increases, the intermediate image may be formed with a large magnification.

Further, the intermediate image to be formed is preferably equal to or less than the same size.
10A and 10B show the display element 103, the projection optical system 104, the intermediate image 105 (105-1, 105-2), and the light deflection element 106. FIG. The microlens array is omitted. Further, the projection optical system is drawn with only one lens in order to avoid complexity, but may be a plurality of optical systems. Here, it is assumed that the projection optical system 104 is a macro lens. Further, although the pixel arrangement of the display element 103 and the intermediate image 105 is omitted, it is assumed that there are many arrangements.
FIG. 10A shows a state in which the intermediate image 105-1 is formed at the same size as the image formed by the display element 103 (that is, the pixel area of the display element). The intermediate image 105-1 is formed in accordance with a microlens array (not shown) on the front surface of the light deflection element 106. The object surface of the macro lens is the surface of the pixel array of the display element. A macro lens forms an intermediate image of a pixel array, and a micro lens array is installed at that position. Further, the object plane of the subsequent projection optical system becomes the image plane of the pixel reduced by the microlens array.

Next, FIG. 10B shows a state in which the intermediate image 105-2 is formed at a smaller magnification than the image formed by the display element 103 (that is, the pixel area of the display element).
In this case, it can be seen that the size of the microlens array and the light deflection element 106 (not shown) may be small. Reducing the size can reduce the cost. Further, when changing the alignment direction of the liquid crystal element, it is necessary to form a uniform horizontal electric field over the entire surface of the light deflection element 106. This is because if the electric field is inhomogeneous in the plane, the change in the orientation of the liquid crystal molecules becomes uneven and the image quality deteriorates.

Here, when the size of the macro lens or the light deflection element 106 is reduced, the formation of a uniform electric field is facilitated, leading to an improvement in image quality. Further, the smaller the size, the easier it is to make the thickness of the liquid crystal layer uniform, and the image quality can be improved.
Thus, by making the magnification of the intermediate image equal to or less than the same size as the image formed by the display element, the size of the light deflection element can be reduced and the cost can be reduced, and the accuracy of the light deflection element can be improved. High quality can be achieved.

A simple way to form an intermediate image is to use a macro lens. FIG. 11 shows the optical system.
114a is a macro lens. The object surface of the macro lens 114a is the surface of the pixel array of the display element 113, and a micro lens array is installed on the image surface. The object surface of the lens 114b is an intermediate image formed on or inside the light deflection element 115b, and the image surface is a screen 118. The macro lens 114a is preferably telecentric, and more preferably bilateral telecentric.
Reference numeral 111 denotes a light source, 112 denotes a polarization optical system, 116 denotes a control means, and 117 denotes a casing.

An example of a deflection optical system using two microlens arrays is shown in FIG.
The first microlens 120 is fabricated on the light deflection element 121, the second microlens 122 is fabricated by itself, and the two are bonded together. By using a plurality of microlenses in this manner, various aberrations can be reduced, and the light collection (light utilization) efficiency can be improved, and the image quality can be further improved. Reference numeral 123 denotes a transparent substrate, and 124 denotes a liquid crystal.

FIG. 13 shows a microlens array in which the vicinity of the apex of the microlens is substantially flat.
The microlens 130 does not have a condensing function with respect to the light 131 incident near the apex of the lens, but has a condensing function only with respect to the light 132 and 133 incident on the side surface of the lens.

  A contrast ratio is an index of projector performance. This displays black display and white display and takes the ratio of the illuminance. A typical example is a contrast ratio defined by ANSI (American National Standard). This is a method using a checker pattern of white (display) and black (display).

  The higher the contrast ratio, the higher the quality of the image. One of the causes for reducing the contrast ratio is a change in the polarization state of linearly polarized light that flies within the projector. This is because linearly polarized light is not ideally maintained and the polarization state changes due to elliptical polarization, rotation of the polarization plane, and the like. Polarized light whose state has changed becomes leakage light, which increases the illuminance of black display and lowers the contrast ratio.

The rotation of the polarization plane increases as the incident angle increases with respect to the plane, and becomes remarkable with a lens having a small radius of curvature. The microlens used in the image display device according to the present invention flattens the vicinity of the apex to suppress the rotation of the polarization plane and improve the contrast ratio.
However, since the pixel cannot be reduced unless the light condensing function is ensured, the lens side surface remains spherical. However, the rotation of the polarization plane is increased on the side surface of the lens, and this shape cannot be significantly reduced, but is advantageous over a lens having no flat portion.
Thus, by using a microlens with a substantially flat apex, leakage light due to rotation of the polarization plane of linearly polarized light on the curved surface of the microlens can be reduced, and high contrast can be achieved.

  Further, the flat portion does not need to be completely flat, may have a gentle curvature, and may be an aspherical surface or a free-form surface.

If the number of display elements used in the projector is reduced, the cost can be reduced. FIG. 15A shows a single-plate projector that uses one display element, and FIG. 15B shows a color separation optical system.
The basic configuration is the same as the configuration example of FIG. 11, but in this configuration example, a color separation optical system 1510 that separates white light into R, G, and B is added to the optical system. In this method, R, G, and B filters are formed on a disc of a translucent member and rotated at a high speed. When white light is incident on the disk as the color separation optical system 1510, it is separated into three primary colors of R, G, and B by time division (field sequential).
As described above, since the optical system based on the combination of the light deflecting element and the microlens array is applied to the single-plate image display device, the image quality is better and the cost can be reduced than the conventional one.

FIG. 16 shows a three-plate projector using three display elements.
The optical system includes a light source 1601 similar to the light source 111, a polarization optical system 1602 similar to the polarization optical system 112, a first dichroic mirror 1603, a first mirror 1604, a second mirror 1605, a second dichroic mirror 1606, Third mirror 1607, fourth mirror 1608, fifth mirror 1609, first display element 1612, second display element 1611, third display element 1610, cross prism 1613, projection optical system 1614, 1616, light A deflecting optical system 1615 (microlens array 1615a, light deflecting element 1615b) and a screen 1617 are included. In this embodiment, since the display element is a liquid crystal display element, a polarization optical system 1602 is provided.

  That is, the polarization optical system 1602 is arranged on the optical path of the light source 1601 shown in FIG. 16, and the first dichroic mirror 1603 is arranged on the optical path on the emission side of the polarization optical system 1602. On one reflected light path of the dichroic mirror 1603 (upper side in the figure), the first mirror 1604 is inclined 45 ° with respect to the light emitted from the light source 1601, and the reflected light is in the same direction as the light emitted from the light source 1601. Has been placed. On the other reflected light path of the first dichroic mirror 1603 (lower side in this case), the second mirror 1605 is disposed at an angle of 45 ° and the reflected light is in the same direction as the emission direction of the light source 1601. . On the reflection side optical path of the first mirror 1604, a second dichroic mirror 1606 is disposed at an angle of 45 ° so as to face the second mirror 1605. A third mirror 1607 is arranged on the transmission optical path of the second dichroic mirror 1606, and a fifth mirror 1609 is arranged at an angle of 45 ° on the reflection optical path of the second dichroic mirror 1606 so as to face each other. ing. A cross prism 1613 is disposed at the intersection of the reflected light paths of both mirrors 1607 and 1609. On the reflected light path of the second mirror 1605, the fourth mirror 1608 is arranged at an angle of 45 °, and the reflected light path is superimposed on the reflected light path of the third mirror 1607.

A first display element 1612 is disposed on the first mirror 1612 side of the cross prism 1613, a second display element 1611 is disposed on the fifth mirror 1609 side of the cross prism 1613, and the third display element 1612 is disposed on the third prism 1613 side. A third display element 1610 is disposed on the mirror 1607 side.
A projection optical system 1614 is disposed on the exit side of the cross prism 1613, and a light deflection optical system 1615 (microlens array 1615a, light deflection element 1615b) is disposed on the light path on the exit side of the projection optical system 1614. A projection optical system 1616 is disposed on the emission optical path of the light deflection optical system 1615 (microlens array 1615a, light deflection element 1615b), and a screen 1617 is disposed on the emission optical path of the projection optical system 1616.

  Unpolarized white light emitted from the light source 1601 is converted into linearly polarized light by the polarization optical system 1602. This linearly polarized light is divided into light of one color and two colors by the first dichroic mirror 1603 (a combination of R, G, and B). The light divided into two colors goes to the first mirror 1604, and the light divided into one color goes to the second mirror 1605 (this will be called the first light). The light reflected by the first mirror 1604 enters the second dichroic mirror 1606, and the two colors are separated (referred to as second light and third light). Light that goes to the third mirror 1607 is called third light, and light that goes to the fifth mirror 1609 is called second light.

  The first light is reflected by the second mirror 1605 and reflected by the fourth mirror 1608 and enters the first display element 1612. The second light is reflected by the fifth mirror 1609 and enters the second display element 1611. The third light is reflected by the third mirror 1607 and enters the third display element 1610. The first to third lights are modulated (or not modulated) by the liquid crystal of the display element, are incident on the cross prism 1613, are color-combined, and travel to the subsequent optical system. The projection optical system 1614 forms an intermediate image of the pixel array of the first to third display elements at the position of the microlens array 1615a, and the formed intermediate image is projected onto the screen 1617 by the projection optical system 1616.

When a line-sequential display element is used, in the conventional example, it is necessary to make the display element and the light deflection element adjacent to each other. This is because the light has a divergence angle, so if the distance between the two elements is increased, the light spreads accordingly, and the light emitted from the pixel is incident on a wide area of the light deflection element. This is for degrading the image quality. Further, the size of the light deflection element increases with the spread. For this reason, in a three-plate projector, the same number of light deflecting elements, that is, three, are required for each color display element, resulting in high costs. By forming an intermediate image by the projection optical system as in the present embodiment, only one optical deflection element is required, and it is possible to provide a high-quality image, while reducing the cost and size. Can be planned. Further, the power consumption required for the optical deflection element may be one sheet.
As described above, since the optical system based on the combination of the deflecting element and the microlens is applied to the three-plate projector, the image quality can be further improved.

In a single-plate image display device, light deflection need not necessarily be performed for the three colors R, G, and B, and only one color may be used.
In the case of a single-plate image display device, R, G, and B are incident on the light deflecting element in a time-sharing manner. Therefore, when light is deflected for each color, the light deflecting element needs to be driven three times faster. As a result, the load increases. However, this load can be reduced if the light deflection is only one color. Further, a normal inexpensive nematic liquid crystal or the like can be used without requiring a high-speed response, and the cost can be reduced.

Also, the color to be deflected is preferably green.
This is because green has the highest relative visibility for humans, and is therefore more effective than light deflecting the other two colors R and B.

The direction of light deflection is not limited to two directions, horizontal and vertical, but may be an oblique direction. The oblique direction means that the direction is shifted with respect to the vertical or horizontal direction (vertical or horizontal) of the pixel array 1801, and the deflection amount is adjusted to √2 times the pitch of the pixels 1803 as will be described later. It is preferable. In other words, when the pixel is rectangular, the oblique direction means that the pixel is deflected obliquely with respect to the rectangular side of the pixel.
An optical system that deflects in an oblique direction is shown in FIGS.
The example shown in FIG. 17A has basically the same configuration as the example shown in FIG. 11, but the half-wave plate 1700 includes a lens 114a and a light deflection optical system 115 (a microlens array 115a, a light deflection element). 115b). The functions of the half-wave plate 1700 are shown in FIGS. Both figures are views as seen from the z-axis.
First, in FIG. 17B, an arrow 1710 is linearly polarized light emitted from the lens 114a, and the direction of the arrow indicates the vibration direction of the electric field. A dotted line arrow 1711 of the half-wave plate 1700 indicates a slow axis of the half-wave plate 1700. It is assumed that it is rotated 22.5 ° clockwise from the y-axis. The vibration plane of the linearly polarized light transmitted through the half-wave plate 1700 in the direction of the arrow 1710 is rotated so that the electric field is oscillated at 45 ° from the x (y) axis as indicated by the arrow 1712 in FIG. It becomes linearly polarized light whose surface is rotated. A dotted arrow 1713 of the light deflection optical system 115 (microlens array 115a, light deflection element 115b) indicates the deflection direction. When linearly polarized light in the direction of the arrow 1712 is incident, the light is deflected in the direction of the arrow. This makes it possible to deflect light in an oblique direction.

Projected images on the screen are shown in FIGS.
The pixel array 1801 can be shifted in an oblique direction to be displayed like the pixel array 1802 (FIG. 18A → FIG. 18B). Preferably, since the amount of deflection is diagonal, it is adjusted to √2 times (arrow 1804) the pitch of the pixels 1803. This adjusted √2 times oblique deflection is a combination of vertical and horizontal deflections. Therefore, only the deflection in the oblique direction can provide an effect close to that in the vertical and horizontal four directions.
FIG. 19A shows a case where a diagonal line 1901 is displayed by pixels without light deflection. If the light is deflected obliquely, it can be seen that jaggy (jagged edges) is reduced as shown by the oblique line 1902 in FIG. By deflecting light in an oblique direction, it is possible to obtain an image close to the same image quality as being deflected in four directions.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

  The present invention can be used for an image display device such as a projector and a head-mounted display, an optical switch, and an imaging optical system.

(A) is a conceptual diagram which shows one Embodiment of the image display apparatus to which the image display method which concerns on this invention is applied, (b) is the projection optical system vicinity of the image display apparatus shown to (a). It is a side enlarged view. (A) is the figure which looked at the display element 3 from the front (optical axis), (b) is the explanatory drawing. 3 is a timing chart of the display element 3 shown in FIG. 4 is a timing chart in which the timing chart shown in FIG. 3 and the optical deflection timing chart are combined. It is a figure which shows the structure and function of the optical deflection element used for the image display apparatus which concerns on this invention. It is a figure which shows the optical deflection | deviation element divided into two. It is a figure which shows the timing chart of the optical deflection | deviation element shown in FIG. It is a figure which shows the case where light is deflected to x-axis and y-axis or horizontal and vertical. It is a figure which shows the element which integrated the micro lens array and the optical deflection element. It is a figure which shows the spatial light modulation element 103, the projection optical system 104, the intermediate image 105, and the light deflection element 106. It is a figure which shows the simple optical system which forms an intermediate image. It is a figure which shows an example of the polarization optical system using two microlens arrays. It is a figure which shows the micro lens array in which the vertex vicinity of a micro lens is substantially flat. It is explanatory drawing of the pixel arrangement | sequence formed on a screen. (A) shows a single-plate projector using a single spatial light modulator, and (b) shows a color separation optical system. It is a figure which shows the three plate-type projector using three spatial light modulation elements. It is a figure which shows the optical system which performs the shift of a diagonal direction. It is a figure which shows the projection image on a screen. (A) is a figure which shows the case where a diagonal line is displayed with a pixel, without deflecting light, and the case where a diagonal line is displayed with the pixel which carried out the light deflection diagonally. It is a figure which shows the prior art example of the image display apparatus which combined the transmissive | pervious liquid crystal spatial light modulation element and the deflection element by a liquid crystal element + quartz plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Polarization optical system 3 Display element 4a, 4b, 4c, 4d Projection optical system 5a, 5b Light polarization element 6 Control means 7 Case 8 Screen

Claims (8)

  A light source, a display element that forms an image by line-sequential; a projection optical system that forms an intermediate image of a pixel array of the display element in an optical path of light from the display element; and a position of the intermediate image An image display device comprising: a microlens array; and an optical deflection element that is provided on an emission side of the microlens array and deflects light in a plurality of regions.   2. The image display device according to claim 1, wherein the microlens array and the light deflection element are integrated.   3. The image display device according to claim 1, wherein the intermediate image is equal to or less than equal magnification.   An image display device comprising a plurality of the microlens arrays according to any one of claims 1 to 3.   5. The image display device according to claim 1, wherein the microlens array has a substantially flat portion around a vertex. 6.   6. The image display device according to claim 1, wherein three of the spatial light modulation elements are used.   The image display device according to claim 1, wherein the direction of light to be deflected is oblique with respect to a side of a rectangular pixel included in the display element.   An image is formed line-sequentially by a display element using light from a light source, an intermediate image of a pixel array included in the display element is formed, and a plurality of light emitted from a microlens array provided at the position of the intermediate image An image display method characterized by deflecting light in a region.

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