Patent Publication Number: US-2005140934-A1

Title: Projection device

Description:
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 10-2003-0102318 filed in Korea on Dec. 31, 2003, the entire contents of which are hereby incorporated by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a projection device, and more particularly, to a projection device in which an image of a resolution higher than a resolution of a display panel included therein can be displayed.  
      2. Description of the Background Art  
      Generally, a projection device is a device, which is composed of a light source and an optical system and is adapted to magnify an image and to project the magnified image onto a screen. In the past, a projection device in which a cathode ray tube (CRT) is mounted was usually employed. Recently, various kinds of projectors using a liquid crystal display (LCD) panel, a digital mirror device (DMD) panel or a liquid crystal on silicon (LCoS) panel and the like have been commercialized.  
      In the projection device having the LCD panel mounted in, in the case of a three-panel type, three liquid crystal panels have the three colors of spectrum red, blue and green pass pixels of the liquid crystal and have a lens collect light that have passed the pixels to produce an image.  
      In the projection device having the DMD panel mounted in, thousands of fine mirrors corresponding to pixels are integrated into a chip called DMD. The mirrors having a slant form an image depending on the degree of reflection of light.  
      Furthermore, the projection device having the LCoS panel mounted in has a silicon wafer into which a LCD is integrated. It is advantageous in that the number of pixels is less limited than that of the LCD or DMD mode.  
      Of the various projection devices, the projection devices of the LCD mode and the DMD mode cannot provide an image of a maximum resolution  720   p  in terms of a mounted panel. The projection device having the LCoS panel mounted in is advantageous in that it can provide a resolution higher than that of the projection device of the LCD mode and the DMD mode, but is disadvantageous in that the price of the projection device is high.  
     SUMMARY OF THE INVENTION  
      Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the background art.  
      An object of the present invention is to provide a high resolution projection device in which an image of a high resolution can be provided by using a digital display panel that supports a low resolution.  
      A projection device according to Claim  1  of the present invention is a projection device that projects an image signal onto a screen, the projection device includes image forming means that forms an image by using an inputted image signal, and image shift means that transmits the image intact or shifts the image, and projects the intact or shifted image onto the screen.  
      A projection method according to Claim  6  of the present invention is a projection method in which an image signal is projected onto a screen, the projecting method comprising the steps of: an image forming step of forming an image by using an inputted image signal, and an image shift step of transmitting the image intact or shifting the image, thus projecting the image onto the screen.  
      A projection device according to Claim  11  of the present invention is a projection device that projects an image signal onto a screen, the projection device including partial image forming means that divides an image signal constituting one screen so that the image signal is suitable for a resolution of a display panel, thus forming several partial images, and image shift means, which transmits or shifts the several partial images and thus projects the image onto the screen.  
      A projection method according to Claim  17  of the present invention is a projection method that projects an image signal onto a screen, the projection method includes a partial image forming step of dividing an image signal constituting one screen so that the image signal is suitable for a resolution of a display panel, thus forming several partial images, and an image shift step of transmitting or shifting the several partial images, thus projecting the image onto the screen.  
      A projection device according to Claim  22  of the present invention is a projection device that projects an image signal onto a screen, the projection device including a display driving unit that transforms an inputted image signal, which constitutes one screen, into a partial image signal so that the image signal is suitable for a resolution of a display panel, an image forming unit including the display panel, the image forming unit converting the partial image signal into an image optical signal, an optical path changing unit that forms a partial image by using the image optical signal, an image shift unit, which transmits the partial image intact in a first state and shifts the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the partial image outputted from the image shift unit onto the screen.  
      A projection device according to Claim  48  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projecting device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to n th  partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to n th  partial images outputted from the image shift unit onto the screen.  
      A projection device according to Claim  57  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projection device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to n th  partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to n th  partial images outputted from the image shift unit onto the screen, wherein the display panel is three transmission-type LCDs, the optical path changing unit includes a X-prism, and the image shift unit includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      A projection device according to Claim  58  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projection device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to n th  partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to n th  partial images outputted from the image shift unit onto the screen, wherein the display panel is a single DMD panel, the optical path changing unit includes a TIR prism, and the image shift unit includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      According to a projection device in accordance with the present invention, an image of a high resolution can be provided by using a digital display panel that supports a low resolution. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.  
       FIG. 1  is a block diagram of a projection device, which can increase a resolution according to the present invention;  
       FIG. 2  is a block diagram of a display driving unit included in the projection device according to the present invention;  
       FIG. 3  is a view for explaining the operation of the display driving unit according to the present invention;  
       FIG. 4  shows an operating waveform of the display driving unit according to the present invention;  
       FIG. 5  is a block diagram of a projection device in which a resolution can be increased according to a first embodiment of the present invention; and  
       FIGS. 6 and 7  are block diagrams of a projection device in which a resolution can be increased according to a second embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings.  
      A projection device according to Claim  1  of the present invention is a projection device that projects an image signal onto a screen, the projection device includes image forming means that forms an image by using an inputted image signal, and image shift means that transmits the image intact or shifts the image, and projects the intact or shifted image onto the screen.  
      In the invention according to Claim  1 , the image forming means forms an image by using an inputted image signal. The image shift means transmits the formed image intact or shifts the image, thus projecting the image. Accordingly, even a projection device including a display panel of a low resolution can form a partial image so as to be suitable for the display panel of the low resolution, and then properly project the partial image onto the screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      According to Claim  2 , in the projection device according to Claim  1 , the image shift means includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  2 , the image shift means includes the polarization conversion unit and the birefringence unit, and performs a function of shifting the image.  
      According to Claim  3 , in the projection device according to Claim  2 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      In the invention according to Claim  3 , the number of each of the polarization conversion unit and the birefringence unit, which constitute the image shift means, can be one or more.  
      According to Claim  4 , in the projection device according to Claim  1 , the image shift means includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  4  is the projection device in which the image shift means is composed of the transmitting body and the piezoelectric ceramic element, unlike Claim  2 , thereby performing the function of shifting the image.  
      According to Claim  5 , in the projection device according to Claim  4 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  5 , it is possible to shift the image by controlling the movement of the transmitting body by means of the piezoelectric ceramic element.  
      A projection method according to Claim  6  of the present invention is a projection method in which an image signal is projected onto a screen, the projecting method comprising the steps of: an image forming step of forming an image by using an inputted image signal, and an image shift step of transmitting the image intact or shifting the image, thus projecting the image onto the screen.  
      In the invention according to Claim  6 , an inputted image signal is formed by an image. The image signal is transmitted intact or shifted, thus being projected onto a screen. Accordingly, even a projection device including a display panel of a low resolution can form a partial image so as to be suitable for the display panel of the low resolution, and then properly project the partial image onto the screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      According to Claim  7 , in the projection method according to Claim  6 , the image shift step is performed by an image shift means including a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  7 , the image shift means is composed of the polarization conversion unit and the birefringence unit, thus performing a function of shifting an image.  
      According to Claim  8 , in the projection method according to Claim  7 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      In the invention according to Claim  8  the number of the polarization conversion unit and the birefringence unit, which constitutes the image shift means, can be one or more.  
      According to Claim  9 , in the projection method according to Claim  6 , the image shift step is performed by image shift means including a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  9  is a projection method in which the image shift means is composed of the transmitting body and the piezoelectric ceramic element, unlike Claim  2 , thereby performing the function of shifting the image.  
      According to Claim  10 , in the projection method according to Claim  9 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  10 , the piezoelectric ceramic element can shift the image by controlling the movement of the transmitting body.  
      A projection device according to Claim  11  of the present invention is a projection device that projects an image signal onto a screen, the projection device including partial image forming means that divides an image signal constituting one screen so that the image signal is suitable for a resolution of a display panel, thus forming several partial images, and image shift means, which transmits or shifts the several partial images and thus projects the image onto the screen.  
      In the invention according to Claim  11 , an image signal constituting one screen is divided according to a resolution of a display panel by using the image forming means, thus forming several partial images. The several partial images are transmitted intact or shifted by using the image shift means, and are then projected onto the screen. Accordingly, even a projection device including a display panel of a low resolution can form a partial image so as to be suitable for the display panel of the low resolution, and then properly project the partial image onto the screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      According to Claim  12 , in the projection device according to Claim  11 , the image shift means includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  12 , the image shift means includes the polarization conversion unit and the birefringence unit, and performs a function of shifting the image.  
      According to Claim  13 , in the projection device according to Claim  12 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      In the invention according to Claim  13 , the number of each of the polarization conversion unit and the birefringence unit, which constitute the image shift means, can be one or more.  
      According to Claim  14 , in the projection device according to Claim  11 , the image shift means includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  14  is the projection device in which the image shift means is composed of the transmitting body and the piezoelectric ceramic element, unlike Claim  2 , thereby performing the function of shifting the image.  
      According to Claim  15 , in the projection device according to Claim  14 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  15 , it is possible to shift the image by controlling the movement of the transmitting body by means of the piezoelectric ceramic element.  
      According to Claim  16 , in the projection device according to any one of Claims  11  to  15 , the image shift means can be disposed at a given position between the display panel and the screen.  
      In the invention according to Claim  16 , the image shift means can be disposed at a given position of a predetermined region of the projection device.  
      A projection method according to Claim  17  of the present invention is a projection method that projects an image signal onto a screen, the projection method includes a partial image forming step of dividing an image signal constituting one screen so that the image signal is suitable for a resolution of a display panel, thus forming several partial images, and an image shift step of transmitting or shifting the several partial images, thus projecting the image onto the screen.  
      In the invention according to Claim  17 , an image signal constituting one screen is divided according to a resolution of a display panel by using the image forming means, thus forming several partial images. The several partial images are transmitted intact or shifted by using the image shift means, and are then projected onto the screen. Accordingly, even a projection device including a display panel of a low resolution can form a partial image so as to be suitable for the display panel of the low resolution, and then properly project the partial image onto the screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      According to Claim  18 , in the projection method according to Claim  17 , the image shift step is performed by an image shift means including a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  18 , the image shift step is performed by an image shift means including a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave, so that a function of shifting an image can be performed.  
      According to Claim  19 , in the projection method according to Claim  18 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      In the invention according to Claim  19 , the number of the polarization conversion unit and the birefringence unit, which constitutes the image shift means, can be one or more.  
      According to Claim  20 , in the projection method according to Claim  17 , the image shift step is performed by image shift means including a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  20  is a projection method in which the image shift step is performed by image shift means including a transmitting body, and a piezoelectric ceramic element connected to the transmitting body, unlike Claim  18 , so that a function of shifting the image can be performed.  
      According to Claim  21 , in the projection method according to Claim  20 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  21 , the piezoelectric ceramic element can shift the image by controlling the movement of the transmitting body.  
      A projection device according to Claim  22  of the present invention is a projection device that projects an image signal onto a screen, the projection device including a display driving unit that transforms an inputted image signal, which constitutes one screen, into a partial image signal so that the image signal is suitable for a resolution of a display panel, an image forming unit including the display panel, the image forming unit converting the partial image signal into an image optical signal, an optical path changing unit that forms a partial image by using the image optical signal, an image shift unit, which transmits the partial image intact in a first state and shifts the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the partial image outputted from the image shift unit onto the screen.  
      In the invention according to Claim  22 , an image signal constituting one screen is divided so as to be suitable for a resolution of a display panel by using the display driving unit, the image forming unit and the optical path changing unit, thus forming several partial images. The image shift unit transmits the several partial images intact or shifts them, and then projects the partial images onto the screen. Accordingly, even a projection device including a display panel of a low resolution can form a partial image so as to be suitable for the display panel of the low resolution, and then properly project the partial image onto the screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      According to Claim  23 , in the projection device according to Claim  22 , the display driving unit includes a resolution conversion unit for forming the partial image signal, and a driving control unit for controlling the first and second states of the image shift unit.  
      In the invention according to Claim  23 , the display driving unit includes the resolution conversion unit and the driving control unit.  
      According to Claim  24 , in the projection device according to Claim  23 , the display driving unit further includes a format conversion unit for, if the image signal constituting the one screen is a signal of an interlace mode, converting the image signal into a signal of a progressive mode.  
      In the invention according to Claim  24 , the display driving unit further includes the format conversion unit so that the image signal can operate in the same manner even if it is a signal of an interlace mode.  
      According to Claim  25 , in the projection device according to Claim  22 , the image shift means includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  25 , the image shift means includes the polarization conversion unit and the birefringence unit, and performs a function of shifting the image.  
      According to Claim  26 , in the projection device according to Claim  25 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      In the invention according to Claim  26 , the number of each of the polarization conversion unit and the birefringence unit, which constitute the image shift means, can be one or more.  
      According to Claim  27 , in the projection device according to Claim  22 , the image shift means includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  27  relates to the projection device in which the image shift means is composed of the transmitting body and the piezoelectric ceramic element, unlike Claim  25 , thereby performing the function of shifting the image.  
      According to Claim  28 , in the projection device according to Claim  27 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  28 , it is possible to shift the image by controlling the movement of the transmitting body by means of the piezoelectric ceramic element.  
      According to Claim  29 , in the projection device according to Claim  22 , the image shift unit is disposed between the display panel and the optical path changing unit.  
      According to Claim  30 , in the projection device according to Claim  22 , the image shift unit is disposed between the optical path changing unit and the projection lens unit.  
      According to Claim  31 , in the projection device according to Claim  22 , the image shift unit is disposed between the projection lens unit and the screen.  
      The invention according to Claims  29  to  31  indicates a detailed position in which the image shift unit can be disposed within the projection device.  
      According to Claim  32 , in the projection device according to Claim  22 , the display panel is a single DMD panel, and the optical path changing unit includes a TIR prism.  
      According to Claim  33 , in the projection device according to Claim  22 , the display panel is a single DMD panel, and the optical path changing unit includes a dichroic mirror.  
      According to Claim  34 , in the projection device according to Claim  22 , the display panel is two or more DMD panels, and the optical path changing unit includes a X-prism.  
      According to Claim  35 , in the projection device according to Claim  22 , the display panel is two or more DMD panels, and the optical path changing unit includes a dichroic mirror.  
      According to Claim  36 , in the projection device according to Claim  22 , the display panel is a single LCD panel of a transmission type, and the optical path changing unit includes a TIR prism.  
      According to Claim  37 , in the projection device according to Claim  22 , the display panel a single LCD panel of a transmission type, and the optical path changing unit includes a dichroic mirror.  
      According to Claim  38 , in the projection device according to Claim  22 , the display panel is a single LCD panel of a transmission type, and the optical path changing unit includes a PBS.  
      According to Claim  39 , in the projection device according to Claim  22 , the display panel is two or more LCD panels of a transmission type, and the optical path changing unit includes a X-prism.  
      According to Claim  40 , in the projection device according to Claim  22 , the display panel is two or more LCD panels of a transmission type, and the optical path changing unit includes a dichroic mirror.  
      According to Claim  41 , in the projection device according to Claim  22 , the display panel is two or more LCD panels of a transmission type, and the optical path changing unit includes a PBS.  
      According to Claim  42  in the projection device according to Claim  22 , the display panel is a single LCoS panel, and the optical path changing unit includes a TIR prism.  
      According to Claim  43 , in the projection device according to Claim  22 , the display panel is a single LCoS panel, and the optical path changing unit includes a dichroic mirror.  
      According to Claim  44 , in the projection device according to Claim  22 , the display panel is a single LCoS panel, and the optical path changing unit includes a PBS.  
      According to Claim  45 , in the projection device according to Claim  22 , the display panel is two or more LCoS panels, and the optical path changing unit includes a X-prism.  
      According to Claim  46 , in the projection device according to Claim  22 , the display panel is two or more LCoS panels, and the optical path changing unit is a dichroic mirror.  
      According to Claim  47 , in the projection device according to Claim  22 , the display panel is two or more LCoS panels, and the optical path changing unit is a PBS.  
      The invention according to Claims  32  to  47  is an implementation of actual materials, which can be applied to the display panel and the optical path changing unit. Real products can be implemented by using the materials.  
      A projection device according to Claim  48  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projecting device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to nth partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to nth partial images outputted from the image shift unit onto the screen.  
      In the invention according to Claim  48 , a person can view the screen with a resolution of an inputted image signal by using the display panel that supports only the number of a scanning line, which is 1/n times greater than that of scanning lines of an image signal constituting one screen.  
      According to Claim  49 , in the projection device according to Claim  48 , the display driving unit includes a resolution conversion unit for forming the partial image signals, and a driving control unit for controlling the first and second states of the image shift unit.  
      In the invention according to Claim  49 , the resolution conversion unit of the display driving unit converts an inputted image signal of one screen into a partial image signal so as to be suitable for the display panel, and the driving control unit controls a state of the image shift unit.  
      According to Claim  50 , in the projection device according to Claim  49 , the display driving unit further includes a format conversion unit which, if the image signal constituting the one screen is a signal of an interlace mode, converts the image signal into a signal of a progressive mode.  
      In the invention according to Claim  50 , an image signal constituting one screen, which is inputted to the display driving unit, can be applied to even a signal of an interlace mode.  
      According to Claim  51 , in the projection device according to Claim  48 , the resolution conversion unit forms the n number of the partial image signals by sampling an image signal corresponding to the order of the scanning lines having the same remnant when the order of the scanning lines of the image signal constituting the one screen is divided by n.  
      In the invention according to Claim  52 , data of an image signal constituting one screen can be divided into n number of partial images by means of the resolution conversion unit.  
      According to Claim  52 , in the projection device according to Claim  49 , the resolution conversion unit forms the n number of the partial image signals in such a way as to n-divide a reference clock of the image signal constituting the one screen and then sample the image signal constituting the one screen at the rising edge and the falling edge of the n-divided clocks.  
      In the invention according to Claim  52 , the resolution conversion unit forms n number of partial images in another method. Even in this method, n number of partial images can be formed.  
      According to Claim  53 , in the projection device according to Claim  48 , the image shift unit includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      In the invention according to Claim  53 , the image shift means includes the polarization conversion unit and the birefringence unit, and performs a function of shifting an image.  
      According to Claim  54 , in the projection device according to Claim  53 , the polarization conversion unit and the birefringence unit are one or more in number, respectively.  
      The invention according to Claim  54  represents that the polarization conversion unit and the birefringence unit, which constitutes the image shift means, can be constructed one or more in number.  
      According to Claim  55 , in the projection device according to Claim  48 , the image shift unit includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  55  relates to a projection device in which the image shift means includes the transmitting body and the piezoelectric ceramic element, unlike the invention according to Claim  53 , thereby performing a function of shifting an image.  
      According to Claim  56 , in the projection device according to Claim  55 , the transmitting body can be moved, and can transmit or shift the image by way of the movement.  
      In the invention according to Claim  56 , the piezoelectric ceramic element can control the movement of the transmitting body to shift the image.  
      A projection device according to Claim  57  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projection device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to nth partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to nth partial images outputted from the image shift unit onto the screen, wherein the display panel is three transmission-type LCDs, the optical path changing unit includes a X-prism, and the image shift unit includes a polarization conversion unit that converts light into an S wave or a P wave, and a birefringence unit that causes birefringence in the S wave or the P wave.  
      The invention according to Claim  57  discloses an embodiment in which the display panel that supports only the number of scanning lines which is 1/n times greater than the number of scanning lines of an image signal constituting one screen is three LCDs of a transmission type, the optical path changing unit includes the X-prism, and the image shift unit has the polarization conversion unit. Thereby, a partial image is formed to be suitable for a display panel of a low resolution and is properly projected onto a screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      A projection device according to Claim  58  of the present invention is a projection device including a display panel that supports the number of scanning lines, which is 1/n times greater than the number of scanning lines of an image signal constituting one screen, the projection device including a display driving unit that converts the image signal constituting the one screen into n number of partial image signals so that the image signal is suitable for the display panel, an image forming unit including the display panel, wherein the image forming unit converts the n number of the partial image signals into n number of image optical signals, an optical path changing unit that forms n number of partial images by using the n number of the image optical signals, an image shift unit, which transmits a first partial image among the n number of the partial image intact in a first state, and shifts second to nth partial images among the n number of the partial image in a second state, under the control of the display driving unit, and a projection lens unit that projects the first to nth partial images outputted from the image shift unit onto the screen, wherein the display panel is a single DMD panel, the optical path changing unit includes a TIR prism, and the image shift unit includes a transmitting body, and a piezoelectric ceramic element connected to the transmitting body.  
      The invention according to Claim  58  discloses an embodiment in which the display panel that supports only the number of scanning lines which is 1/n times greater than the number of scanning lines of an image signal constituting one screen is the single DMD panel, the optical path changing unit includes the TIR prism, and the image shift unit includes the transmitting body and the piezoelectric ceramic element. Thereby, a partial image is formed to be suitable for a display panel of a low resolution and is properly projected onto a screen. This makes a person view the screen with a resolution of an image signal constituting one screen.  
      Hereinafter, the present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings.  
       FIG. 1  is a block diagram of a projection device, which can increase a resolution according to the present invention.  
      Referring to  FIG. 1 , the high resolution projection device of the present invention includes an image forming unit  100 , an optical path changing unit  110 , an image shift unit  120 , a projection lens unit  130  and a display driving unit  140 .  
      &lt;Image Forming Unit&gt; 
      The image forming unit  100  includes a digital display panel that supports the number of pixels smaller than a resolution of a frame to be displayed. Preferably, the digital display panel according to the present invention supports pixels of 1/n times (n is a natural number) of the whole resolution for forming a frame.  
      Hereinafter, one frame to be displayed is called the whole image. An image formed by the digital display panel is called an image optical signal.  
      For example, if the whole image, which is projected by the projection device according to the present invention and is thus viewed to the eyes of a person has a resolution of  1080   p,  a resolution that is supported by the digital display panel is  540   p.  Examples of this digital display panel may include a LCD panel, a DMD panel and an LCoS panel and so on.  
      &lt;Optical Path Changing Unit&gt; 
      The optical path changing unit  110  reflects each of n number of image optical signals, which are outputted from the image forming unit  100 , to form n number of partial images depending on the image optical signals. This optical path changing unit  110  can be selected depending on the type of a panel included in the image forming unit  100 , or can be omitted.  
      For example, in the case where a single DMD panel is used as the digital display panel of the image forming unit  100 , the optical path changing unit  110  includes a Total Internal Reflection (TIR) prism. If a single LCoS panel is used as the digital display panel, the optical path changing unit  110  includes a Polarizing Beam Splitter (PBS). If three LCoS panels are used as the digital display panel, the optical path changing unit  110  includes a PBS or a X-prism. If three transmission-type LCDs are used as the digital display panel, the optical path changing unit  110  includes a X-prism. Finally, if a transmission-type a single LCD panel is used as the digital display panel, the optical path changing unit  110  is not required.  
      &lt;Image Shift Unit&gt; 
      The image shift unit  120 , in a first state, transmits a first partial image, which is outputted from the optical path changing unit  110  intact, and, in a second state, consecutively shifts and transmits second to nth partial images, which are outputted from the optical path changing unit  110 , on a 1/n pixel basis.  
      As the first partial image and the second to nth partial images are sequentially transmitted, the whole image of a resolution higher than that of the partial image itself is displayed.  
      In this time, if n is 2, the first state is a turn-off state, and the second state is in a turn-on state. If n is 3 or more, the first state is in a turn-off state, and the second state is in a state where the remaining second to nth partial image are sequentially shifted.  
      For example, if a resolution of the whole image to be displayed is  1080   p,  the image forming unit  100  and the optical path changing unit  110  output a first partial image having a resolution of  540   p.  In this time, if the image shift unit  120  is turned off, the first partial image passes through the image shift unit  120  and is then projected through the projection lens unit  130  without any change.  
      Then, the image forming unit  100  and the optical path changing unit  110  output a second partial image having a resolution of  540   p.  If the image shift unit  120  is turned on, the second partial image is shifted by ½ pixel by means of the image shift unit  120  and is then projected through the projection lens unit  130 .  
      If this process is performed, while the first partial image which is projected with the image shift unit  120  being turned off and the second partial image which is projected with the screen shift unit being turned on are consecutively displayed on the screen, the whole image is formed by way of an afterimage effect. For example, while a first partial image of  540   p  and a second partial image of  540   p  are displayed, the whole image of  1080   p  is formed by way of an afterimage effect.  
      Preferably, the first partial image of  540   p,  which is projected with the image shift unit  120  being turned off, corresponds to an odd-numbered line of a frame of  1080   p.  The second partial image of  540   p,  which is projected with the image shift unit  120  being turned on, corresponds to an even-numbered line of a frame of  1080   p,  which is shifted by the image shift unit  120 .  
      &lt;Display Driving Unit&gt; 
      The display driving unit  140  converts an externally input image signal into an image signal of a-predetermined format, and converts the converted image signal into n number of partial image signal the resolution of which is 1/n-times higher than that of the converted image signal, so that the image forming unit  100  forms n number of image optical signals corresponding to the n number of the partial image signals. Driving of the first state and the second state of the image shift unit  120  is thus controlled according to the n number of the image optical signals.  
       FIG. 2  is a block diagram of the display driving unit  140  included in the projection device according to the present invention. Referring to  FIG. 2 , the display driving unit  140  includes a format conversion unit  141 , a resolution conversion unit  143  and a driving control unit  145 .  
      The format conversion unit  141  converts an inputted image signal that supports a resolution of an interlace mode into an image signal that supports a resolution of a progressive mode.  
      The resolution conversion unit  143  samples image signals corresponding to lines of order having the same remnant when order of each line constituting the resolution of the progressive mode is divided by n, and combines the sampled image signals to form n number of partial image signals.  
      For example, if n=2, the resolution conversion unit  143  samples image signals corresponding to odd-numbered lines that constitute the resolution of the progressive mode and then combines the image signal into one, and samples image signals corresponding to an even-numbered line and then combines the image signals into one.  
      Furthermore, in the case where n=3, if order of respective lines that constitute the resolution of the progressive mode is divided by 3, the remnant is 0, 1 or 2. Thus, image signals corresponding to the first, fourth, seventh, fifth, eighth, . . . lines are combined into one, and image signals corresponding to the third, sixth, ninth, . . . lines into are combined one.  
      The driving control unit  145  controls the operation of each of the format conversion unit  141  and the resolution conversion unit  143 , and controls the operation of the first state and the second state of the image shift unit  120 .  
       FIG. 3  is a view for explaining the operation of the display driving unit  140  according to the present invention. In this time, n=2.  
      Referring to  FIG. 3 , reference numeral  310  shows a state where an image signal of a resolution  1080   i  of the interlace mode is converted into an image signal of a resolution  1080   p  of the progressive mode by means of the format conversion unit  141  shown in  FIG. 2 .  
      Reference numeral  320  shows a state where the image signal of  1080   p  is converted into an image signal of  540   p  that corresponds to an odd-numbered line of the image signal of  1080   p  by means of the resolution conversion unit  143  shown in  FIG. 2 .  
      Reference numeral  330  shows a state where the image signal of  1080   p  is converted into the image signal of  540   p  corresponding to an even-numbered line of the image signal of  1080   p  by means of the resolution conversion unit  143  shown in  FIG. 2 .  
      Reference numeral  340  shows an image of  1080   p,  which is displayed when the partial image of  540   p  corresponding to the odd-numbered line and the partial image of  540   p  corresponding to the even-numbered line, which are generated by the resolution conversion unit  143  of  FIG. 2 , are overlapped.  
      That is, the driving control unit  145  of the display driving unit  140  turns off the image shift unit  120  simultaneously when the image signal of  540   p,  which corresponds to the odd-numbered line, is applied to the image forming unit  100 .  
      Then, a partial image corresponding to the image signal of  540   p,  which corresponds to the odd-numbered line, is projected onto the screen through the projection lens unit  130 .  
      The driving control unit  145  of the display driving unit  140  then turns on the image shift unit  120  while applying the image signal of  540   p,  which corresponds to the even-numbered line, to the image forming unit  100 .  
      Thus, while the partial image corresponding to the image signal of  540   p,  which corresponds to the even-numbered line, is shifted by ½ pixel, it is projected onto the screen through the projection lens unit  130 , so that a complete image of  1080   p  is formed by way of the afterimage effect. Accordingly, assuming that an image of 60 frames is projected onto the screen per second, the projection device according to the present invention can project  120  partial images per second.  
      Through this process, an image having the resolution of  1080   p  is formed through the image forming unit  100  that supports the resolution of  540   p.    
       FIG. 4  shows an operating waveform of the display driving unit  140  according to the present invention;  
      FIGS.  4 ( a ) and  4 ( b ) show a reference clock waveform and a data waveform corresponding to the resolution of  1080   p,  which are transmitted from the format conversion unit  141  to the resolution conversion unit  143  in  FIG. 2 .  
       FIG. 4 ( c ) shows a clock waveform corresponding to a resolution of  540   p,  which is 2-divided by the resolution conversion unit  143 . FIGS.  4 ( d ) and  4 ( e ) are a data waveform corresponding to an odd-numbered line, and a data waveform corresponding to an even-numbered line, respectively.  
      In this time, as shown in  FIG. 4 ( c ), the resolution conversion unit  143  form a clock waveform corresponding to  540   p  by 2-dividing the clock waveform corresponding to  1080   p  to.  
      Thereafter, the resolution conversion unit  143  samples the data waveform corresponding to the resolution of  1080   p  at the rising edge of the clock waveform corresponding to  540   p,  thus forming the data waveform corresponding to the odd-numbered line as shown in  FIG. 4 ( d ). Also, the resolution conversion unit  143  samples the data waveform corresponding to the resolution of  1080   p  at the falling edge of the clock waveform corresponding to  540   p,  thus forming the data waveform corresponding to the even-numbered line as shown in  FIG. 4 ( e ).  
      The above-described waveforms are waveforms where n=2. Generally, a clock waveform is n-divided to form a clock waveform corresponding to a resolution of 1/n times of a resolution of the whole image.  
       FIG. 5  is a block diagram of a projection device in which a resolution can be increased according to a first embodiment of the present invention.  
      Referring to  FIG. 5 , in the first embodiment of the projection device according to the present invention, an image forming unit  100  includes three LCDs, an optical path changing unit  110  includes a X-prism, and an image shift unit  120  includes a polarization conversion unit  121  and a birefringence unit  123 . In this time, the birefringence unit  123  according to a first embodiment of the present invention is calcite.  
      That is, light that has passed through the respective transmission-type LCD panels, which corresponds to R, G and B, are converted into an S wave or a P wave by means of the polarization deflection device  121 . The light that is converted into the S wave by the polarization deflection device  121  is shifted by the birefringence unit  123 . The light that is converted into the P wave by the polarization deflection device  121  passes through the birefringence unit  123  intact.  
      Accordingly, if the display driving unit  140  controls the LCD panels according to the data waveform of  540   p,  which corresponds to the odd-numbered line formed by the resolution conversion unit  143  of the display driving unit  140 , the light that has passed through the LCD panels forms one partial image, while being reflected from the X-prism.  
      In this time, if the display driving unit  140  operates the polarization conversion unit  121  to convert the partial image into the P wave, the birefringence unit  123  transmits the partial image converted into the P wave.  
      Thereafter, if the display driving unit  140  controls the LCD panel according to the data waveform of  540   p  corresponding to the even-numbered line formed by the resolution conversion unit  143  of the display driving unit  140 , the light that has passed through the LCD panel forms another one partial image. In this time, the driving control unit  145  of the display driving unit  140  operates the polarization conversion unit  121  to convert the partial image into the S wave, the birefringence unit  123  shifts the one partial image.  
      In this time, since the amount of the shift is a semi-pixel, an image of  1080   p  is formed as two partial images are overlapped.  
       FIGS. 6 and 7  are block diagrams of a projection device in which a resolution can be increased according to a second embodiment of the present invention.  
      Referring to  FIGS. 6 and 7 , in the second embodiment of the projection device according to the present invention, an image forming unit  100  includes a DMD panel, an optical path changing unit  110  includes a TIR prism, and an image shift unit  120  includes a flat panel glass  129  having a piezoelectric ceramic element  127  attached to both ends.  
      As shown in  FIG. 6 , in the case where the display driving unit  140  forms a partial image of  540   p  corresponding to an odd-numbered line through a DMD panel while not applying a signal to the piezoelectric ceramic element  127  attached to both ends of the flat panel glass  129 , the flat panel glass becomes parallel to the DMD panel, so that a position onto which the image of  540   p  is projected returns to its original position.  
      Furthermore, as shown in  FIG. 7 , in the case where the display driving unit  140  forms the partial image of  540   p,  which corresponds to the even-numbered line, through the DMD panel while applying a signal to the piezoelectric ceramic element  127 , pressure is generated in the piezoelectric ceramic element  127 . Thus, as an equilibrium state of the flat panel glass and the DMD panel is upset, the partial image shifts. Therefore, the partial image corresponding to the odd-numbered line and the partial image corresponding to the even-numbered line are overlapped to form the image of  1080   p.    
      In the aforementioned second embodiment, if n=2 or n =3, the display driving unit controls the amount of a voltage applied to the piezoelectric ceramic element  127  to be different, so that n number of the partial images is sequentially shifted by the 1/n pixel.  
      According to a projection device in accordance with the present invention, an image of a high resolution can be provided by using a digital display panel that supports a low resolution.  
      As described above, the present invention can provide a projection device including a display panel having a resolution lower than that of an image signal constituting one screen.  
      The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following Claims.