• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A light source, a polarizing beam splitter surface for separating light rays into S- and P-polarizations, and a color separation surface for separating the polarization into red, green and blue light beams in a direction orthogonal to the optical axis A prism block having a?,?? Plate for delaying the phase of the polarized light so that the phase difference becomes 1/4 wavelength, a mirror for reflecting the polarized light passed through the?? The pixels are arranged in a matrix, and a liquid crystal panel for light modulating the red, green and blue light beams incident from the color separation surface, and projecting the red, green and blue light beams passing through the liquid crystal plate on the screen. Disclosed is a projection image display device including a projection lens. Since two polarization components, S-polarized light and P-polarized light, can be used, the light efficiency can be greatly increased.
    公开号:KR19990043705A
    申请号:KR1019970064747
    申请日:1997-11-29
    公开日:1999-06-15
    发明作者:김진태
    申请人:전주범；대우전자 주식회사；
    IPC主号:
    专利说明:

    Projection type image display device
    BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a projection image display device, and more particularly, to a projection type display device including a liquid crystal panel to improve light efficiency and to be broadcast in a bright room.
    In general, a spatial light modulator, which is an apparatus for projecting optical energy onto a screen, may be applied to various fields such as optical communication, image processing, and information display apparatus. Typically, such devices are classified into a direct-view image display device and a projection-type image display device according to a method of displaying optical energy on a screen.
    An example of a direct-view image display device is a CRT (Cathode Ray Tube). The CRT device is called a CRT, which has excellent image quality but increases in weight and volume as the screen is enlarged, leading to an increase in manufacturing cost. There is.
    Projection type image displays include liquid crystal displays (LCDs), deformable mirror devices (DMDs), and actuated mirror arrays (AMAs). Such projection image display devices can be further divided into two groups according to their optical characteristics. That is, devices such as LCDs can be classified as Transmissive spatial light modulators, while DMD and AMA can be classified as Reflective spatial light modulators.
    An LCD device is a display device using a liquid crystal that can electrically control the transmittance of light. The display device using the LCD (or liquid crystal projector) has a very simple optical structure, which makes it possible to reduce light weight and shorten the size of a CRT projector. Can be. In addition, it is widely used as a display device for high-definition television (HDTV) and video conferencing because large screens and high image quality can be obtained.
    A liquid crystal panel used in a liquid crystal projector is commonly known as a matrix liquid crystal panel, in which pixels are arranged in a matrix in two directions perpendicular to each other, and are driven individually by a driving voltage to provide optical Change characteristics. The driving voltage can be applied to individual pixels by a simple matrix system, and non-linear two-terminal elements such as metal-insulating metal (MIM) or three-terminal switching elements such as TFT (thin film transistor) are placed for each pixel. It can be applied to each pixel alternately by the active matrix system.
    In such an active matrix system, the pixels must be arranged at a minimum pitch, thereby reducing the ratio of openings occupied by the pixels to the total area (aperture ratio). The transmittance of the liquid crystal plate is determined by the efficiency of the polarizer and the aperture ratio of each pixel. Therefore, in order to increase the aperture ratio, a method of disposing a microlens array on the light incident surface or the light incident surface and the exit surface of the display element corresponding to each pixel is mainly used. This microlens array includes multiple lens elements arranged at the same pitch as the pitch between the pixels, wherein light is focused on each pixel through lens elements disposed on the light incident surface.
    1 is a schematic diagram showing the configuration of a projection display device using a conventional liquid crystal plate.
    Referring to FIG. 1, a conventional projection display device 10 includes a projection lens 24 for projecting colored light L, and a red light R, green light G, and blue light B. Each of the liquid crystal plates 20a, 20b, and 20c. The liquid crystal plates 20a, 20b, and 20c change their transmittances according to the applied image signal to transmit or block red, green, and blue lights. The transmitted light is projected by the projection lens 24 into a ray L comprising three color rays.
    In addition, the conventional projection display device 10 includes a metal halide lamp 12, a microlens array 14, a dichroic mirror 16a, 16b, and a mirror for emitting light rays. 17a, 17b, 17c, condenser lenses 18a, 18b, and dichroic prism 22 are further provided.
    The microlens array 14 is composed of multiple lens elements arranged at the same pitch as the pitch between the pixels of the liquid crystal plates 20a, 20b, and 20c, and each pixel through lens elements disposed on a light incident surface. To focus the light on.
    The dichroic mirrors 16a and 16b serve to separate white light emitted from the halogen metal lamp 12 into three primary colors of light, that is, red light, green light, and blue light. The dichroic mirrors 16a and 16b are reflectors made of many thin layers of materials having different refractive indices. The dichroic mirrors 16a and 16b reflect light of some color and transmit light of all other colors.
    The dichroic prism 22 has a dichroic mirror reflecting only red light and transmitting other light and a dichroic mirror reflecting only blue light and transmitting other light in the form of 'X'. Thus, by reflecting the red light and blue light incident on the three mutually perpendicular surfaces of the prism and transmitting the green light as it is, three color light rays are synthesized and incident to the projection lens 24.
    The operation principle of the conventional projection display device 10 will be briefly described as follows.
    After white light is emitted from the halogen metal lamp 12, the white light is focused by the microlens array 14 and irradiated to the dichroic mirror 16a. Among the white light, green light G and blue light B pass through dichroic mirror 16a, while red light R is reflected on it. The red light R is reflected by the mirror 17a and then passes through the R-liquid crystal plate 20a as the transmittance of the R-liquid crystal plate 20a changes. The red light R then enters the dichroic prism 22 and is reflected by a dichroic mirror that reflects only the red light in the dichroic prism 22. The reflected red light R enters the projection lens 24.
    On the other hand, the green light G and the blue light B transmitted by the dichroic mirror 16a reflect the green light G by the dichroic mirror 16b and the blue light B is transmitted. The green light G passes through the G-liquid crystal plate 20b as the transmittance of the G-liquid crystal plate 20b changes. The green light G passing through the G-liquid crystal plate 20b enters the dichroic prism 22, passes through the dichroic prism 22, and enters the projection lens 24.
    The blue light B transmitted through the dichroic mirror 16b passes through the condenser lens 18a and is then reflected by the mirror 17b to enter the condenser lens 18b. The blue light B passing through the condenser lens 18b is reflected by the mirror 17c and then passes through the B-liquid crystal plate 20c as the transmittance of the B-liquid crystal plate 20c changes. The blue light B passing through the B-liquid crystal plate 20c enters the dichroic prism 22 and is then reflected by a dichroic mirror reflecting only the blue light in the dichroic prism 22. The reflected blue light B enters the projection lens 24.
    In this way, dichroic prism 22 synthesizes three rays (red, green, and blue rays), and projection lens 24 displays the synthesized rays L on a screen (not shown). To project on.
    2A and 2B are schematic views for explaining the structure and operating principle of the liquid crystal plate 20 shown in FIG.
    Referring to FIGS. 2A and 2B, the liquid crystal plate 20 includes a polarizer and an analyzer spaced at regular intervals, and a liquid crystal injected into a gap between the polarizer and the analyzer. Twisted Nematic (TN) liquid crystal is mainly used as the liquid crystal, and each transmission axis of the polarizer and the analyzer is perpendicular to each other.
    Looking at the operating principle of the liquid crystal plate 20, when no voltage is applied, as shown in Figure 2a, the incident light transmitted through the polarizer is a linear polarization (phase difference is mπ) rotated 90 ° by the TN liquid crystal Permeate. On the other hand, when a voltage is applied to the liquid crystal plate 20, as shown in FIG. 2B, due to the dielectric anisotropy of the TN liquid crystal, the light incident through the polarizer may not be linearly polarized because the TN liquid crystal is standing upright. Since the transmission axis of the analyzer is perpendicular to the transmission axis of the polarizer, the incident light transmitted through the polarizer is completely blocked by the analyzer and cannot be transmitted.
    In general, incident light is light that is not polarized but is polarized while passing through a polarizer. Polarized light consists largely of P-polarized light and S-polarized light, where P-polarized light is a component of a wave polarized in the plane of incidence perpendicular to the interface and defined by the wave vector of the incident wave, and S-polarized light is incident The component of the wave polarized perpendicular to the plane. When no voltage is applied to the liquid crystal plate 20, when the polarization direction of the polarizer is in the P-polarization direction, as shown in FIG. 2A, the S-polarized light is absorbed from the polarizer while the P-polarized light is transmitted through the polarizer. The transmitted P-polarized light is rotated 90 ° by the TN liquid crystal and is converted into S-polarized light, and then passes through the analyzer.
    As described above, in the conventional projection display device, only one polarization component, that is, S-polarized light or P-polarized light, is transmitted by the polarizer of the liquid crystal plate and projected onto the screen by the projection lens. In general, the light utilization efficiency of the projection display device using the liquid crystal plate is mainly affected by the light collimation optics and the liquid crystal plate. In the conventional projection display device as described above, since one polarization component, that is, S-polarized light or P-polarized light is always lost by the polarizer of the liquid crystal plate, the light efficiency is significantly reduced.
    Accordingly, an object of the present invention is to provide a projection display device including a liquid crystal plate and a projection display device using the same polarization components to increase the light efficiency to be able to air even in a bright room and a projection method using the same. .
    1 is a schematic diagram showing the configuration of a conventional projection display device.
    2A and 2B are schematic views for explaining the structure and operating principle of a liquid crystal panel used in the projection display device shown in FIG. 1.
    3 is a schematic view showing the configuration of a projection display device according to the present invention.
    FIG. 4 is a schematic diagram for explaining propagation paths of S-polarized light and P-polarized light by the polarization beam splitter plane and the λ / 4 plate in the apparatus shown in FIG. 3.
    FIG. 5 is an enlarged schematic view of portion 'A' of the apparatus of FIG. 3.
    <Explanation of symbols for main parts of the drawings>
    100: projection display device 102: lamp
    104: reflector 106: condenser lens
    108: prism block 110: polarizing beam splitter surface
    112a, 112b: lambda / 4 plate 114a, 114b: mirror
    116a, 116b, and 116c: color separation surface 118: microlens array
    120: liquid crystal plate 124: projection lens
    The present invention to achieve the above object, the light source for emitting a light ray; A polarizing beam splitter surface positioned on the optical axis of the light source for separating the light rays into S-polarized light and P-polarized light, and in a direction orthogonal to the optical axis, the polarized light being red, green and blue light rays. Prism block having a color separation surface for separating into; A λ / 4 plate for retarding the phase of the polarization such that the phase difference is 1/4 wavelength; A mirror for reflecting polarized light passing through the [lambda] / 4 plate to be incident back to the [lambda] / 4 plate; A liquid crystal panel in which pixels are arranged in a matrix form and light modulating red, green, and blue light rays incident from the color separation surface into an image; And a projection lens for projecting red, green, and blue light rays passing through the liquid crystal plate onto a screen.
    As described above, the present invention is directed to a prism block having a polarization beam splitter surface and a color separation surface such as a dichroic filter by irradiating the light beam emitted from the light source, and thereby radiating the light beam by the polarization beam splitter surface. Separate into polarized light and P-polarized light. The two polarizations separated by the polarizing beam splitter plane are each 1/4 in phase difference by a first λ / 4 plate located in a direction orthogonal to the optical axis of the light source and a second λ / 4 plate located on the optical axis. After changing to the wavelength, it is reflected by the first and second mirrors located on the rear surface of each of the first and second λ / 4 plates and is incident back to the first and second λ / 4 plates. As a result, the polarization changes by 90 ° with respect to the polarizations incident from the polarization beam splitter plane to the first and second λ / 4 plates, respectively, and the two polarizations whose phase difference is changed through the polarization beam splitter plane. It is incident on the color separation surface of the prism block. The color separation surface separates both polarizations into red, green and blue light rays and enters the liquid crystal panel, and the red, green and blue light rays passing through the liquid crystal plate are projected onto the screen through the projection lens.
    Therefore, according to the projection image display device according to the present invention, since both polarization components, that is, S-polarized light and P-polarized light can be used, the light efficiency can be greatly increased.
    Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.
    3 is a schematic diagram showing the configuration of a projection image display device using the liquid crystal plate according to the present invention.
    Referring to FIG. 3, the projection image display apparatus 100 according to the present invention includes a light source 102, a reflector 104, a condenser lens 106, a prism block 108, and a polarizing beam splitter surface for emitting light rays. 110, first λ / 4 plate 112a, second λ / 4 plate 112b, first mirror 114a, second mirror 114b, first color separation surface 116a, second color The separation surface 116b, the reflection surface 116c, the microlens array 118, the transmissive liquid crystal plate 120, and the projection lens 124 are included.
    The light source 102 preferably emits long wavelength infrared (LWIR) to ultraviolet (UV) light in the spectrum as a halogen metal lamp of 170W to 250W. The reflector 104 serves to reflect the light rays emitted from the lamp 102 in the opposite direction to the condenser lens 106 and back to the condenser lens 106.
    The prism block 108 has a polarizing beam splitter surface 110 located on the optical axis of the light source 102 and three color separation surfaces 116a, 116b, 116c located in a direction orthogonal to the optical axis. The polarizing beam splitter surface 110 is manufactured to perform the roles of the polarizer and the beam splitter at the same time. The polarizing beam splitter surface 110 is a thin film coated on an oblique surface of a right-angle prism and attached with an adhesive. When the non-polarized monochromatic light is incident on the polarizing beam splitter surface 110, light polarized in a direction perpendicular to the straight direction comes out. S-polarized light, which is an electric field vector perpendicular to the plane of incidence, emerges in a direction perpendicular to and parallel to the plane of incidence. The electric field vector, P-polarized light, is transmitted. In the present invention, since the incident light is polarized by using the polarizing beam splitter surface 110, the transmissive liquid crystal plate 120 includes only a liquid crystal and an analyzer without a polarizer.
    The first color separation surface 116a and the second color separation surface 116b are preferably composed of a dichroic filter. The dichroic filter is an optical filter that selectively passes light by wavelength. In addition, the color separation surface may be formed of a dichroic mirror.
    The first [lambda] / 4 plate 112a and the second [lambda] / 4 plate 112b serve to invert the light in the polarization state so that the phase difference becomes 90 degrees. For example, when linearly polarized light exits a λ / 4 plate, it becomes left or right polarized light due to the refractive index anisotropy of the λ / 4 plate. In the present invention, in order to use both the S-polarized light and the P-polarized light separated by the polarizing beam splitter surface 110, the first In the advancing direction of the S-polarized light, that is, the direction perpendicular to the optical axis of the light source 102. The / 4 plate 112a is disposed, and the second λ / 4 plate 112b is disposed on the traveling direction of the P-polarized light, that is, the optical axis.
    The first mirror 114a and the second mirror 114b are located at the rear surfaces of the first λ / 4 plate 112a and the second λ / 4 plate 112b, respectively, and the first λ / 4 plate 112a. And reflects the polarized light that has passed through the second λ / 4 plate 112b and back enters the first λ / 4 plate 112a and the second λ / 4 plate 112b.
    The liquid crystal plate 120 changes its transmittance according to an applied image signal to transmit or block red, green, and blue light rays. The microlens array 118 is positioned on the light incident surface of the liquid crystal plate 120, and one lens element 119 corresponds to the three pixels 122a, 122b, and 122c of the liquid crystal plate. It consists of
    The projection lens 124 serves to project red, green, and blue light rays transmitted through the liquid crystal plate 120 onto a screen (not shown).
    FIG. 4 shows S-polarized light by the polarization beam splitter surface 110, the first [lambda] / 4 plate 112a and the second [lambda] / 4 plate 112b in the projection image display device 100 shown in FIG. And a schematic diagram for explaining the propagation path of P-polarized light. FIG. 5 is an enlarged view of portion 'A' of the apparatus of FIG. 3, and is a schematic diagram illustrating propagation paths of red, green, and blue light rays in the microlens array 118 and the liquid crystal plate 120.
    Hereinafter, the operation principle of the projection image display apparatus 100 according to the present invention will be described in more detail with reference to FIGS. 3 to 5.
    After white light is emitted from the halogen metal lamp 102, the white light is focused on the polarizing beam splitter face 110 of the prism block 108 by the condenser lens 106. Since the polarizing beam splitter surface 110 reflects S-polarized light and transmits P-polarized light, the reflected S-polarized light is first λ / 4 plate 112a located in a direction orthogonal to the optical axis of the lamp 102. Is incident on. The linear S-polarized light incident on the first λ / 4 plate 112a has a phase difference changed to a quarter wavelength to change to a left circle or right circle polarized light, and then is located on a rear surface of the first λ / 4 plate 112a. Reflected by the mirror 114a, it is changed back to right or left circularly polarized light. Right or left circularly polarized light reflected from the first mirror 114a is reversely incident on the first λ / 4 plate 112a and is incident from the polarization beam splitter surface 110 to the first λ / 4 plate 112a. The phase difference becomes 90 [deg.] For the linear S-polarized light, which is changed to linear P-polarized light. The P-polarized light thus obtained penetrates through the polarization beam splitter surface 110 and is incident on the first color separation surface 116a. The first color separation surface 116a transmits the red light R and the green light G out of the white light and reflects only the blue light B to enter the liquid crystal plate 120. Among the red light R and the green light G transmitted through the first color separation surface 116a, the green light G is reflected by the second color separation surface 116b and the red light R is transmitted to the liquid crystal plate. Incident on 120. The red light R transmitted through the second color separation surface 116b is reflected by the reflection surface 116c and is incident on the liquid crystal plate 120.
    Meanwhile, the linear P-polarized light transmitted through the polarization beam splitter surface 110 is incident on the second λ / 4 plate 112b located on the optical axis of the lamp 102. The linear P-polarized light incident on the second λ / 4 plate 112b has a phase difference changed to a quarter wavelength to change to a left circle or right circle polarization, and then a second second λ / 4 plate 112b is located on the rear surface of the second λ / 4 plate 112b. Reflected by the mirror 114b, it is changed back to right or left circularly polarized light. Right or left circularly polarized light reflected from the second mirror 114b is incident back to the second λ / 4 plate 112b and is incident from the polarization beam splitter surface 110 to the second λ / 4 plate 112b. The phase difference becomes 90 ° for the linear P-polarized light, which is changed into linear S-polarized light. The S-polarized light thus obtained is reflected by the polarization beam splitter surface 110 and is incident on the first color separation surface 116a. The first color separation surface 116a transmits the red light R and the green light G out of the white light and reflects only the blue light B to enter the liquid crystal plate 120. Among the red light R and the green light G transmitted through the first color separation surface 116a, the green light G is reflected by the second color separation surface 116b and the red light R is transmitted to the liquid crystal plate. Incident on 120. The red light R transmitted through the second color separation surface 116b is reflected by the reflection surface 116c and is incident on the liquid crystal plate 120.
    The blue light B of the two polarization components (S-polarized light and P-polarized light) reflected by the first color separation surface 116a, the second color separation surface 116b, and the reflective surface 116c through the above-described steps, respectively ), The red light R and the green light G are incident on the liquid crystal plate 120 through the microlens array 118. As shown in FIG. 5, the microlens array 118 is formed such that one lens element 119 corresponds to the three pixels 122a, 122b and 122c of the liquid crystal plate 120. Therefore, the blue light B incident on one lens element 119 of the microlens array 118 is focused on the B-pixel 122c of the liquid crystal plate, and the red light R is focused on the R-pixel 122a. The green light G is focused on the G-pixel 122b.
    The liquid crystal plate 120 changes its transmittance according to an applied image signal to transmit or block red, green, and blue light rays. Therefore, as the transmittance of the liquid crystal plate 120 changes, the red, green, and blue light rays passing through the liquid crystal plate 120 are projected onto the screen through the projection lens 124, thereby displaying a color image.
    As described above, the present invention irradiates a light beam emitted from a light source to a prism block having a polarization beam splitter surface and a color separation surface such as a dichroic filter, and transmits the light beam by S-polarization and P- by the polarization beam splitter surface. Separate by polarized light. The two polarizations separated by the polarizing beam splitter plane are each 1/4 in phase difference by a first λ / 4 plate located in a direction orthogonal to the optical axis of the light source and a second λ / 4 plate located on the optical axis. After changing to the wavelength, it is reflected by the first and second mirrors located on the rear side of each of the first λ / 4 plate and the second λ / 4 plate, and is reversed to the first λ / 4 plate and the second λ / 4 plate. Incident. As a result, the polarization changes by 90 ° with respect to the polarizations incident from the polarization beam splitter plane to the first and second λ / 4 plates, respectively, and the two polarizations whose phase difference is changed through the polarization beam splitter plane. It is incident on the color separation surface of the prism block. The color separation surface separates both polarizations into red, green and blue light rays and enters the liquid crystal panel, and the red, green and blue light rays passing through the liquid crystal plate are projected onto the screen through the projection lens.
    Therefore, according to the projection image display device according to the present invention, since both polarization components, that is, S-polarized light and P-polarized light can be used, the light efficiency can be greatly increased. Therefore, it is possible to provide a liquid crystal projector that can be broadcast even in a bright room.
    Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.
    权利要求:
    Claims (4)
    [1" claim-type="Currently amended] A light source 102 for emitting light rays;
    A polarizing beam splitter surface 110 positioned on the optical axis of the light source for separating the light beam into S-polarized light and P-polarized light, and located in a direction orthogonal to the optical axis and separating the polarized light into red, green and blue light rays. A prism block 108 having a first color separation surface 116a, a second color separation surface 116b, and a reflecting surface 116c to make;
    The phase difference of the polarization is delayed so that the phase difference becomes 1/4 wavelength, and the first λ / 4 plate 112a located in the direction orthogonal to the optical axis of the light source 102 and the second located on the optical axis λ / 4 plate 112b;
    Reflecting the polarized light passing through the first λ / 4 plate 112a and the second λ / 4 plate 112b, it is incident to the first λ / 4 plate 112a and the second λ / 4 plate 112b Mirrors 114a and 114b for making;
    The pixels 122 are arranged in a matrix form and light modulate red, green, and blue light rays incident from the first color separation plane 116a, the second color separation plane 116b, and the reflective surface 116c into an image. A liquid crystal plate 120 in which three pixels form one pixel; And
    And a projection lens (124) for projecting red, green, and blue light rays passing through the liquid crystal plate onto the screen.
    [2" claim-type="Currently amended] The projection image display apparatus according to claim 1, further comprising a condenser lens (106) for focusing light rays emitted from said light source onto said polarizing beam splitter surface.
    [3" claim-type="Currently amended] The liquid crystal display of claim 1, wherein one lens element 119 is positioned on a light incident surface of the liquid crystal plate 120 and corresponds to multiple lens elements corresponding to three pixels 122a, 122b, and 122c of the liquid crystal plate. And a microlens array (118) made of the projection type image display device.
    [4" claim-type="Currently amended] The projection image display device according to claim 1, wherein the first color separation surface (116a) and the second color separation surface (116b) are composed of three dichroic filters.
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    同族专利:
    公开号 | 公开日
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1997-11-29|Application filed by 전주범, 대우전자 주식회사
    1997-11-29|Priority to KR1019970064747A
    1999-06-15|Publication of KR19990043705A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019970064747A|KR19990043705A|1997-11-29|1997-11-29|Projection type image display device|
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