Abstract:
A spatial light modulator includes a pixel array including a plurality of pixel elements arranged in a form of a matrix; a word line extending along and connected to a row of the pixel elements pixel elements; and a plate line for transmitting additional modulating signals to said pixel array extended along each row of the pixel array and connected to the pixel elements in a first row and a second row constituting two different rows. 
     A method for controlling a spatial light modulator implemented with plate lines extended along rows of a pixel array including a plurality of pixel elements arranged in a form of a matrix, comprising: selecting and transmitting a data access signal on a first plate line; and selecting and transmitting a subsequent data access signal on a second plate line with the second plate line located at N rows away from the first plate line, where N is a positive integer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Non-provisional application of a Provisional Application 61/069,454 filed on Mar. 15, 2008 and a Continuation in Part Application of a Non-provisional patent application Ser. No. 12/291,922 filed on Nov. 13, 2008 and another Non-provisional application Ser. No. 12/074,033 filed on Mar. 1, 2008. This Application is further a Continuation in Part Application of a Non-provisional patent application Ser. No. 11/121,543 filed on May 4, 2005 issued into U.S. Pat. No. 7,268,932 and another Non-provisional application Ser. No. 10/698,620 filed on Nov. 1, 2003. The application Ser. No. 11/121,543 is a Continuation In Part (CIP) Application of three previously filed Applications. These three Applications are 10/698,620 filed on Nov. 1, 2003, 10/699,140 filed on Nov. 1, 2003 now issued into U.S. Pat. No. 6,862,127, and Ser. No. 10/699,143 filed on Nov. 1, 2003 now issued into U.S. Pat. No. 6,903,860 by the Applicant of this patent applications. The disclosures made in these patent applications are hereby incorporated by reference in this patent application. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates generally to a video project apparatus implemented with a spatial light modulator. More particularly, the invention relates to a spatial light modulator implemented with plate lines for transmitting signals to modulate said pixel array. 
         [0004]    2. Description of the Related Art 
         [0005]    Even though there are significant advances made in recent years on the technologies of implementing electromechanical micro-mirror devices as spatial light modulator, there are still limitations and difficulties when employed to provide high quality images display. Specifically, when the display images are digitally controlled, the image qualities are adversely affected due to the fact that the image is not displayed with sufficient number of gray scales. 
         [0006]    Electromechanical micro-mirror devices have drawn considerable interest because of their application as spatial light modulators (SLMs). A spatial light modulator requires an array of a relatively large number of micro-mirror devices. In general, the number of required devices ranges from 60,000 to several million for each SLM. Referring to  FIG. 1A , an image display system  1  including a screen  2  is disclosed in a relevant U.S. Pat. No. 5,214,420. A light source  10  is used to generate light beams to project illumination for the display images on the display screen  2 . 
         [0007]    The light  9  projected from the light source is further concentrated and directed toward lens  12  by way of mirror  11 . Lenses  12 ,  13  and  14  form a beam columnator operative to columnate the light  9  into a column of light  8 . A spatial light modulator  15  is controlled by a computer through data transmitted over data cable  18  to selectively redirect a portion of the light from path  7  toward lens  5  to display on screen  2 .  FIG. 1B  shows a SLM  15  that has a surface  16  that includes an array of switchable reflective elements  17 ,  27 ,  37 , and  47 , each of these reflective elements is attached to a hinge  30 . When the element  17  is in an ON position, a portion of the light from path  7  is reflected and redirected along path  6  to lens  5  where it is enlarged or spread along path  4  to impinge on the display screen  2  to form an illuminated pixel  3 . When the element  17  is in an OFF position, the light is reflected away from the display screen  2  and, hence, pixel  3  is dark. 
         [0008]    The on-and-off states of the micromirror control scheme, as that implemented in the U.S. Pat. No. 5,214,420 and in most conventional display systems, impose a limitation on the quality of the display. Specifically, applying the conventional configuration of a control circuit limits the gray scale gradations produced in a conventional system (PWM between ON and OFF states), limited by the LSB (least significant bit, or the least pulse width). Due to the ON-OFF states implemented in the conventional systems, there is no way of providing a shorter pulse width than the duration represented by the LSB. The least intensity of light, which determines the gray scale, is the light reflected during the least pulse width. The limited levels of the gray scale lead to a degradation of the display image 
         [0009]    Specifically,  FIG. 1C  exemplifies, as related disclosures, a circuit diagram for controlling a micromirror according to U.S. Pat. No. 5,285,407. The control circuit includes memory cell  32 . Various transistors are referred to as “M*” where “*” designates a transistor number and each transistor is an insulated gate field effect transistor. Transistors M 5 , and M 7  are p-channel transistors; transistors, M 6 , M 8 , and M 9  are n-channel transistors. The capacitances, C 1  and C 2 , represent the capacitive loads in the memory cell  32 . The memory cell  32  includes an access switch transistor M 9  and a latch  32   a  based on a Static Random Access switch Memory (SRAM) design. All access transistors M 9  on a Row line receive a DATA signal from a different Bit-line  31   a . The particular memory cell  32  is accessed for writing a bit to the cell by turning on the appropriate row select transistor M 9 , using the ROW signal functioning as a Word-line. Latch  32   a  consists of two cross-coupled inverters, M 5 /M 6  and M 7 /M 8 , which permit two stable states that include a state  1  when is Node A high and Node B low, and a state  2  when Node A is low and Node B is high 
         [0010]    The control circuit positions the micro-mirrors to be at either an ON or an OFF angular orientation, as that shown in  FIG. 1A . The brightness, i.e., the number of gray scales of display for a digitally control image system, is determined by the length of time the micro-mirror stays at an ON position. The length of time a micromirror is in an ON position is controlled by a multiple bit word.  FIG. 1D  shows the “binary time intervals” when controlling micromirrors with a four-bit word. As shown in  FIG. 1D , the time durations have relative values of 1, 2, 4, 8, which in turn define the relative brightness for each of the four bits where “1” is the least significant bit and “8” is the most significant bit. According to the control mechanism as shown, the minimum controllable differences between gray scales for showing different levels of brightness is a represented by the “least significant bit” that maintains the micromirror at an ON position. 
         [0011]    For example, assuming n bits of gray scales, one time frame is divided into 2 2 −1 equal time periods. For a 16.7-millisecond frame period and n-bit intensity values, the time period is 16.7/(2 n −1) milliseconds. 
         [0012]    Having established these times for each pixel of each frame, pixel intensities are quantified such that black is a 0 time period, the intensity level represented by the LSB is 1 time period, and the maximum brightness is 2 n −1 time periods. Each pixel&#39;s quantified intensity determines its ON-time during a time frame. Thus, during a time frame, each pixel with a quantified value of more than 0 is ON for the number of time periods that correspond to its intensity. The viewer&#39;s eye integrates the pixel brightness so that the image appears the same as if it were generated with analog levels of light. 
         [0013]    For controlling deflectable mirror devices, the PWM applies data to be formatted into “bit-planes”, with each bit-plane corresponding to a bit weight of the intensity of light. Thus, if the brightness of each pixel is represented by an n-bit value, each frame of data has the n-bit-planes. Then, each bit-plane has a 0 or 1 value for each mirror element. According to the PWM control scheme described in the preceding paragraphs, each bit-plane is independently loaded and the mirror elements are controlled according to bit-plane values corresponding to the value of each bit during one frame. Specifically, the bit-plane according to the LSB of each pixel is displayed for 1 time period. 
         [0014]    Meanwhile, higher levels of resolution and higher grades of gray scales required for better quality display images are in demand for projection apparatuses, especially in recent years due to the increased availability of video images, such as that provided by high definition television (HDTV) broadcasting. 
         [0015]    However, in the gray scale control by the pulse width modulation (PWM), as shown in  FIG. 1D , the expressible gray scale is limited by the length of the time period determined by the LSB. An attempt to add a new control structure to a memory cell of the above described SRAM structure in order to overcome the aforementioned limitation creates another problem, that is, the structure of a complex memory cell, with a larger number of transistors than, for example, the memory cell of a DRAM structure, increases the size of the mechanism. 
         [0016]    Specifically, in order to obtain a higher definition display image, a large number of mirror elements are required. Each of these mirror elements, comprising an SRAM-structured memory cell, must be reduced in size to fit in the space of a certain mounting size (e.g., a predefined package size or chip size). However, the addition of a new control structure to an SRAM-structured memory cell in order to attain a higher level gray scale display image increases the size of the memory cell, thereby inhibiting a higher level display image. 
         [0017]    In light of the above described limitations, it is necessary to solve the technical challenge of realizing a higher gray scale level, which exceeds the conventional method to control the gray scale a display image with pulse width modulation (PWM), while projecting images with a higher definition with memory cells having the simplest possible structure comprising a small number of circuit elements. 
       SUMMARY OF THE INVENTION 
       [0018]    An aspect of the present invention is to provide a new configuration and control process for a video projection apparatus implemented with a spatial light modulation element. The video project apparatus can display images with a higher gray scale and a higher definition without increasing the number of wires. 
         [0019]    A first embodiment of the present invention provides a spatial light modulator that includes a plurality of pixel elements arranged in a form of a matrix; a word line extending along and connected to a row of the pixel elements pixel elements; and a drive line for transmitting additional modulating signals to said pixel array extended along each row of the pixel array and connected to the pixel elements in a first row and a second row constituting two different rows. 
         [0020]    A second embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein the drive lines are connected to the pixel elements arranged on two adjacent rows. 
         [0021]    A third embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein each of the plurality of pixel elements includes first and second memories each including a capacitor and a transistor, a first electrode connected to the first memory, a second electrode connected to the second memory; a third electrode connected to the a first drive line extended along the first row including the pixel element, and a fourth electrode connected to a second drive line extended along the second row not including the pixel element. 
         [0022]    A fourth embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein each of the plurality of pixel elements includes a first memory including first and second capacitors, and a first transistor, a second memory including third and fourth capacitors, and a second transistor, a first electrode connected to the first memory, and a second electrode connected to the second memory; the second capacitor is connected to the first drive line extended along the first row including the pixel element; and the fourth capacitor is connected to the second drive line arranged in the second row not including the pixel element. 
         [0023]    A fifth embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein each of the plurality of pixel elements includes a first memory including a first capacitor and a first transistor, a second memory including a second capacitor and a second transistor, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first capacitor is connected to a first drive line extended along the first row including the pixel element; and the second capacitor is connected to a second drive line extended along the second row not including the pixel element. 
         [0024]    A sixth embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein each of the plurality of pixel elements includes a first memory including a first capacitor, and first and second transistors, a second memory including a second capacitor, and third and fourth transistors, a power supply connected to the second and the fourth transistors, a first electrode connected to the first memory, and a second electrode connected to the second memory; the second transistor is connected to the drive line extended along the first row including the pixel element; and the fourth transistor is connected to the drive line extended along the second row not including the pixel element. 
         [0025]    A seventh embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein each of the plurality of pixel elements includes a first memory including a first capacitor, a first transistor and a first diode, a second memory including a second capacitor, a second transistor and a second diode, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first diode is connected to the drive line extended along the first row including the pixel element; and the second diode is connected to the drive line extended along the second row not including the pixel element. 
         [0026]    An eighth embodiment of the present invention provides the spatial light modulator according to the first embodiment, comprising a mirror device. 
         [0027]    A ninth embodiment of the present invention provides the spatial light modulator according to the first embodiment, wherein the drive line is controlled for defecting a mirror of the pixel element in the first row in an ON direction, and the drive line is controlled simultaneously for deflecting a mirror of the pixel element in the second row in an OFF direction. 
         [0028]    A tenth embodiment of the present invention provides the spatial light modulator according to the first embodiment, further comprising: a driver circuit for transmitting a signal to the pixel element in the second row and simultaneously transmitting the signal to the pixel element in the first row by the drive line. 
         [0029]    An eleventh embodiment of the present invention provides the spatial light modulator according to the first exemplary embodiment, further comprising a driver circuit for transmitting a signal through the drive line to generate and apply a potential on the drive line to drive the pixel element. 
         [0030]    A twelfth embodiment of the present invention provides the spatial light modulator according to the first embodiment, which further comprises a bit line extended along each column of the pixel array and connected to the pixel elements in each column of the pixel array, wherein a driver circuit for transmitting a signal through the drive line for applying a potential on the bit line in the pixel element. 
         [0031]    A thirteenth embodiment of the present invention provides the spatial light modulator according to the first embodiment, further comprising a driver circuit for transmitting a signal through a drive line with a shorter transmission duration than a cycle of an access to the pixel element through the word line. 
         [0032]    A fourteenth embodiment of the present invention provides the spatial light modulator according to the first embodiment, further comprising: a driver circuit for transmitting a signal through a drive line with a shorter transmission duration almost equal to a cycle of an access to the pixel element through the word line. 
         [0033]    A fifteenth embodiment of the present invention provides the spatial light modulator according to the first embodiment, which further comprises a bit line extending along each column of the pixel array and connected to the pixel elements in each column of the pixel array, wherein: each of the plurality of pixel element elements includes a first memory including a first capacitor, and first and second transistors, a second memory including a second capacitor, and third and fourth transistors, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first transistor is connected to the word line and a first bit line; the second transistor is connected to the drive line in the first row including the pixel element, and a second bit line; the third transistor is connected to the word line and a third bit line; the fourth transistor is connected to the drive line extended along the second row not including the pixel element, and a fourth bit line; a driver circuit for synchronously transmitting signals in the first and the second bit lines of different voltages; and the driver circuit further synchronously transmits signals in the third and the fourth bit lines of different voltages. 
         [0034]    A sixteenth embodiment of the present invention provides the spatial light modulator according to the first embodiment, which further comprises a scanning direction switching unit for switching a scanning direction of the drive line between a forward direction and a reverse direction. 
         [0035]    A seventeenth embodiment of the present invention provides a spatial light modulator, which comprises a pixel array including a plurality of pixel element arranged in a form of a matrix; a drive line for transmitting signals for modulating said pixel array extended along each row of the pixel array, and connected to the pixel elements in first row and a second row, wherein a signal is transmitted to a pixel element in the second row while the signal is transmitted by the drive line to the pixel element in the first row. 
         [0036]    An eighteenth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein a driver circuit for transmitting a signal through the drive line to generate and apply a potential on the drive line to drive the pixel element. 
         [0037]    A nineteenth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, which further comprises a bit line extended along each column of the pixel array and connected to the pixel elements in each column of the pixel array, wherein a driver circuit for transmitting a signal through the drive line for generating a potential for applying to the pixel element from the bit line. 
         [0038]    A twentieth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, further comprising: a driver circuit for transmitting a signal through a drive line with a shorter transmission duration than a cycle of an access to the pixel element through a word line and extended along each row of the pixel array and connected to the pixel elements in each row of the pixel array. 
         [0039]    A twenty-first embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein a driver circuit for transmitting a signal through a drive line with a shorter transmission duration almost equal to a cycle of an access to the pixel element through the word line extended along each row of the pixel array and connected to the pixel elements in each row of the pixel array. 
         [0040]    A twenty-second embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, which further comprises a bit line extended along each column of the pixel array and connected to the pixel elements in each column of the pixel array, wherein: each of the plurality of pixel elements includes a first memory including a first capacitor, and first and second transistors, a second memory including a second capacitor, and third and fourth transistors, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first transistor is connected to a word line extended along each row of the pixel array and connected to the pixel elements in each row of the pixel array and a first bit line; the second transistor is connected to the drive line in the first row including the pixel element, and a second bit line; the third transistor is connected to the word line and a third bit line; the fourth transistor is connected to the drive line extended along the second row not including the pixel element, and a fourth bit line; a driver circuit for synchronously transmitting signals of different voltages in the first and the second bit lines; and a driver circuit for synchronously transmitting signals of different voltages in the third and the fourth bit lines. 
         [0041]    A twenty-third embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, which further comprises a scanning direction switching unit for switching a scanning direction of the drive line between a forward direction and a reverse direction. 
         [0042]    A twenty-fourth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein the first row and the second row connected to a same drive line are two adjacent rows. 
         [0043]    A twenty-fifth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein each of the plurality of pixel elements includes first and second memories each including a capacitor and a transistor; a first electrode connected to the first memory, a second electrode connected to the second memory a third electrode connected to the drive line extended along the first row including the pixel element belongs, and a fourth electrode connected to the drive line extended along the second row not including the pixel element. 
         [0044]    A twenty-sixth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein each of the plurality of pixel elements includes a first memory including first and second capacitors, and a first transistor, a second memory including third and fourth capacitors, and a second transistor, a first electrode connected to the first memory, and a second electrode connected to the second memory; the second capacitor is connected to the drive line extended along the first row including the pixel element; and the fourth capacitor is connected to the drive line extended along the second row not including the pixel element. 
         [0045]    A twenty-seventh embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein each of the plurality of pixel elements includes a first memory including a first capacitor and a first transistor, a second memory including a second capacitor and a second transistor, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first capacitor is connected to the drive line extended along the first row including the pixel element; and the second capacitor is connected to the drive line extended along the second row not including the pixel element. 
         [0046]    A twenty-eighth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein each of the plurality of pixel elements includes first memory including a first capacitor, and first and second transistors, a second memory including a second capacitor, and third and fourth transistors, a power supply connected to the second and the fourth transistors, a first electrode connected to the first memory, and a second electrode connected to the second memory; the second transistor is connected to the drive line extended along the first row including the pixel element; and the fourth transistor is connected to the drive line extended along the second row not including the pixel element. 
         [0047]    A twenty-ninth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein each of the plurality of pixel element elements includes a first memory including a first capacitor, a first transistor and a first diode, a second memory including a second capacitor, a second transistor and a second diode, a first electrode connected to the first memory, and a second electrode connected to the second memory; the first diode is connected to the drive line extended along the first row including the pixel element belongs; and the second diode is connected to the drive line extended along the second row not including the pixel element. 
         [0048]    A thirtieth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, comprises a mirror device. 
         [0049]    A thirty-first embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, wherein a driver circuit for transmitting a signal through the drive line for deflecting a mirror of the pixel element in the first row toward an ON direction, and for simultaneously deflecting a mirror of the pixel element in the second row toward an OFF direction. 
         [0050]    A thirty-second embodiment of the present invention provides a method for controlling a spatial light modulator implemented with drive lines extended along rows of a pixel array including a plurality of pixel elements arranged in a form of a matrix, comprising: transmitting a signal to a plurality of pixel elements along selective rows through a plurality of selected drive lines when no signals are transmitted in other drive lines. 
         [0051]    A thirty-third embodiment of the present invention provides the method according to the first embodiment, wherein the step of transmitting a signal to a plurality of pixel elements along selective rows through a plurality of selected drive lines comprising a step of transmitting the signal to a plurality of pixel elements extended along a first row and a second row. A thirty-fourth embodiment of the present invention provides the method according to the second embodiment, wherein the step of transmitting a signal to a plurality of pixel elements along selective rows through a plurality of selected drive lines comprising a step of transmitting the signal to a plurality of pixel elements extended along a first row and a second row adjacent to the first row. 
         [0052]    A thirty-fifth embodiment of the present invention provides a method for controlling a spatial light modulator implemented with drive lines extended along rows of a pixel array including a plurality of pixel elements arranged in a form of a matrix, comprising: selecting and transmitting a data access signal on a first drive line; and selecting and transmitting a subsequent data access signal on a second drive line with the second drive line located at N rows away from the first drive line, where N is a positive integer. 
         [0053]    A thirty-sixth embodiment of the present invention provides the method according to the fourth embodiment, further comprising a step of connecting a drive line to the pixel elements along a first row and a second row in the pixel array. 
         [0054]    A thirty-seventh embodiment of the present invention provides the method according to the fifth embodiment, wherein connecting a drive line to the pixel elements along a first row and a second row with the second row adjacent to the first row in the pixel array. 
         [0055]    A thirty-eight embodiment of the present invention provides the method according to claim  4 , wherein the step of selecting and transmitting a data access signal on a first and second drive lines located with N rows between the first and second drive lines comprise a step of select and transmitting the data access signal on two adjacent drive lines with N=0. 
         [0056]    A thirty-ninth embodiment of the present invention provides the method according to the fourth embodiment, wherein the step of selecting and transmitting a data access signal on a first and second drive lines located with N rows between the first and second drive lines comprise a step of select and transmitting the data access signal on two drive lines with N=1. 
         [0057]    A forty embodiment of the present invention provides the method according to the fourth embodiment, wherein the step of selecting and transmitting a data access signal on a first and second drive lines located with N rows between the first and second drive lines comprise a step of select and transmitting the data access signal on two drive lines with N=2. 
         [0058]    A forty-first embodiment of the present invention provides the method according to the fourth embodiment, wherein the step of selecting and transmitting a data access signal on a first and second drive lines located with N rows between the first and second drive lines comprise a step of processing an input video image signal applying a processing result for determining the number of rows represented by N. 
         [0059]    A forty-second embodiment of the present invention provides the method according to the tenth embodiment, wherein the step of processing the input video image signal further comprising a step of determining the input video image signal comprising an interlaced signal or a progressive signal. 
         [0060]    A forty-third embodiment of the present invention provides a method for controlling a spatial light modulator implemented with lines in a pixel array with a plurality of pixel elements arranged in a form of a matrix, comprising partitioning the drive lines into at least two groups and transmitting a signal to a pixel element through the drive lines within each of the groups in a predetermined duration. 
         [0061]    A forty-fourth embodiment of the present invention provides the method according to the twelfth embodiment, further comprising a step of connecting a drive line to the pixel elements along a first row and a second row in the pixel array. 
         [0062]    A forty-fifth embodiment of the present invention provides the method according to the twelfth embodiment, wherein the step of partitioning the drive lines into at least two groups further comprising a step of partitioning the drive lines into a plurality of groups with each group including an equal number of drive lines. 
         [0063]    A forty-sixth embodiment of the present invention provides the method according to the twelfth embodiment, wherein the step of partitioning the drive lines into at least two groups further comprising a step of partitioning the drive lines into groups according to driver circuit configuration for controlling the drive lines. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0064]      FIG. 1A  illustrates the basic principle of a projection display using a micromirror device, as disclosed in a prior art patent; 
           [0065]      FIG. 1B  is a top view diagram showing the configuration of mirror elements of a portion of a micromirror array of a projection apparatus disclosed in a prior art patent. 
           [0066]      FIG. 1C  is a circuit diagram showing the configuration of a drive circuit of mirror elements of a projection apparatus disclosed in a prior art patent. 
           [0067]      FIG. 1D  shows the scheme of Binary Pulse Width Modulation (Binary PWM) of conventional digital micromirrors for generating a grayscale; 
           [0068]      FIG. 2  is a functional block diagram showing an exemplary configuration of a display system according to a preferred embodiment of the present invention. 
           [0069]      FIG. 3  is a diagram showing an exemplary configuration of a spatial light modulation element constituting a display system according to a preferred embodiment of the present invention. 
           [0070]      FIG. 4  is a conceptual diagram showing the configuration of an individual pixel unit constituting a spatial light modulator according to a preferred embodiment of the present invention. 
           [0071]      FIG. 5  is a top view for showing a diagonal perspective view of a mirror device comprised of, in two dimensions on a device substrate, a plurality of mirror elements, each controlling the reflecting direction of an incident light by the deflection a mirror 
           [0072]      FIG. 6  is a timing diagram showing an exemplary mirror control profile used in a display system according to a preferred embodiment of the present invention. 
           [0073]      FIG. 7A  is a cross-sectional diagram showing the ON state of a micromirror. 
           [0074]      FIG. 7B  is a timing diagram showing the intensity of light projected in the ON state of a micromirror. 
           [0075]      FIG. 7C  is a cross-sectional diagram showing the OFF state of a micromirror. 
           [0076]      FIG. 7D  is a timing diagram showing the intensity of light projected in the OFF state of a micromirror. 
           [0077]      FIG. 7E  is a cross-sectional diagram showing the oscillating state of a micromirror. 
           [0078]      FIG. 7F  is a timing diagram showing the intensity of light projected in the oscillating state of a micromirror. 
           [0079]      FIG. 8  is a functional circuit diagram for explaining a configuration example of a pixel unit in the display system according to the embodiment of the present invention; 
           [0080]      FIG. 9A  is a schematic top view diagram showing an example of the layout of electrodes of the pixel unit shown in  FIG. 8 ; 
           [0081]      FIG. 9B  is a schematic top view diagram showing another example of the layout of electrodes of the pixel unit shown in  FIG. 8 ; 
           [0082]      FIG. 9C  is a schematic top view diagram showing a further example of the layout of electrodes of the pixel unit shown in  FIG. 8 ; 
           [0083]      FIG. 9D  is a cross sectional diagram, taken along line IXC-IXC in  FIG. 9C , of the pixel unit having the layout shown in  FIG. 9C   
           [0084]      FIG. 9E  is a schematic top view diagram showing a further example of the layout of electrodes of the pixel units shown in  FIG. 8 ; 
           [0085]      FIG. 9F  is a schematic top view diagram showing a further example of the layout of electrodes of the pixel units shown in  FIG. 8 ; 
           [0086]      FIG. 10  is a top view diagram showing an example of the connections of the pixel units and plate lines, which are shown in  FIG. 8 ; 
           [0087]      FIG. 11A  is a cross-sectional view showing an example of the OFF state of the pixel unit having the layout shown in  FIG. 9A ; 
           [0088]      FIG. 11B  is a cross-sectional view showing an example of the ON state of the pixel unit having the layout shown in  FIG. 9A ; 
           [0089]      FIG. 11C  is a cross-sectional view showing an example of the intermediate oscillation state of the pixel unit having the layout shown in  FIG. 9A ; 
           [0090]      FIG. 12A  is a functional circuit diagram for explaining the action of the pixel unit shown in  FIG. 8 ; 
           [0091]      FIG. 12B  is a functional circuit diagram for explaining the action of the pixel unit shown in  FIG. 8 ; 
           [0092]      FIG. 12C  is a functional circuit diagram for explaining the action of the pixel unit shown in  FIG. 8 ; 
           [0093]      FIG. 12D  is a functional circuit diagram for explaining the action of the pixel unit shown in  FIG. 8 ; 
           [0094]      FIG. 13A  is a functional circuit diagram showing an example of the layout of peripheral circuits of a pixel array in the display system according to the embodiment of the present invention; 
           [0095]      FIG. 13B  is a functional circuit diagram showing an example of the internal configuration of a plate line address generator (PL Address Generator) shown in  FIG. 13A ; 
           [0096]      FIG. 14  is a functional circuit diagram showing an example of the internal configuration of a plate line address decoder (PL Address Decoder-a) shown in  FIG. 13A ; 
           [0097]      FIG. 15  is a functional circuit diagram showing an example of the internal configuration of a plate line driver (PL Driver) shown in  FIG. 13A ; 
           [0098]      FIG. 16  is a functional circuit diagram showing an example of the internal configuration of a bit line driver (Bitline Driver) shown in  FIG. 13A ; 
           [0099]      FIG. 17  is a table that stipulates the operations of the bit line driver (Bitline Driver) shown in  FIG. 13A ; 
           [0100]      FIG. 18  is a timing chart showing an example of operations of the pixel array of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0101]      FIG. 19A  is a timing diagram showing an example of the settings of a mirror control profile of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0102]      FIG. 19B  is a timing diagram showing an example of the settings of the mirror control profile of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0103]      FIG. 19C  is a timing diagram showing an example of the settings of the mirror control profile of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0104]      FIG. 19D  is a timing diagram showing an example of the settings of the mirror control profile of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0105]      FIG. 20  is a functional circuit diagram showing another modification example of the pixel unit in the display system according to the embodiment of the present invention; 
           [0106]      FIG. 21  is a schematic top view diagram showing the layout of electrodes of the pixel unit shown in  FIG. 20 ; 
           [0107]      FIG. 22  is a timing chart showing an example of operations of the pixel array of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0108]      FIG. 23  is a functional circuit diagram showing a further modification example of the pixel unit in the display system according to the embodiment of the present invention; 
           [0109]      FIG. 24  is a functional circuit diagram showing a further modification example of the pixel unit in the display system according to the embodiment of the present invention; 
           [0110]      FIG. 25  is a timing chart showing an example of operations of the pixel array of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0111]      FIG. 26  is a functional circuit diagram showing a further modification example of the pixel unit in the display system according to the embodiment of the present invention; 
           [0112]      FIG. 27  is a timing chart showing an example of operations of the pixel array of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0113]      FIG. 28  is a functional circuit diagram showing a modification example of the layout of peripheral circuits of the pixel array in the embodiment of the present invention; 
           [0114]      FIG. 29  is a functional circuit diagram showing a further modification example of the pixel unit in the display system according to the embodiment of the present invention; 
           [0115]      FIG. 30  is a functional circuit diagram showing an example of a configuration added to the bit line driver unit (Bitline Driver) in the pixel array having the configuration shown in  FIG. 29 ; 
           [0116]      FIG. 31  is a timing chart showing an example of operations of the pixel array of the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0117]      FIG. 32  is a conceptual diagram showing an example of a control for making a sequential access to plate lines while skipping a plurality of rows in the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0118]      FIG. 33  is a flowchart showing an example of the sequential access control for the plate lines in the spatial light modulator configuring the display system according to the embodiment of the present invention; 
           [0119]      FIG. 34  is a functional block diagram showing an example of a configuration of a projection device in an embodiment of the present invention; and 
           [0120]      FIG. 35  is a functional block diagram showing an example of a configuration of a control unit included in the projection device in the embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0121]    Preferred embodiments according to the present invention are described in detail below with reference to the drawings. 
         [0122]      FIG. 2  is a functional block diagram showing an exemplary configuration of a display system according to a preferred embodiment of the present invention.  FIG. 3  is a block diagram showing an exemplary configuration of a spatial light modulation element implemented in a display system according to a preferred embodiment of the present invention.  FIG. 4  is a functional circuit diagram showing an exemplary configuration of a pixel unit  211  implemented in a spatial light modulator according to the present embodiment. 
         [0123]    An example of the basic configuration of a projection device  100  in the embodiment is initially described, and the embodiments are described thereafter. 
         [0124]    The projection apparatus  100  according to the present embodiment comprises a spatial light modulator  200 , a control apparatus  300 , a light source  510  and a projection optical system  520 . 
         [0125]      FIG. 5  is a top view diagram showing a diagonal perspective of a spatial light modulator wherein multiple mirror elements (i.e., pixel units), which control the reflecting direction of incident light by the deflection of the mirrors, are arrayed in two dimensions on a device substrate. 
         [0126]    As shown in  FIG. 5 , the spatial light modulator  200  is configured by arraying pixel units  211 , each of which comprises an address electrode (not shown in the drawing), an elastic hinge (not shown in the drawing), and a square mirror  212  supported by the elastic hinge, in a two-dimensional array on a substrate  214 . 
         [0127]    The mirror  212  of one pixel unit  211  is controlled by applying a voltage to an address electrode placed on the substrate  214 . 
         [0128]    Meanwhile, the pitch (i.e., the interval) between adjacent mirrors  212  is preferably set anywhere between 4 μm and 14 μm, or more preferably between 5 μm and 10 μm, in consideration of the number of pixels ranging from a super high definition television (i.e., a full HD TV) (e.g., 2048 by 4096 pixels) to a non-full HD TV, and of the sizes of mirror devices. Specifically, the pitch is defined as the distance between the deflection axes of adjacent mirrors  212 . 
         [0129]    Specifically, the area size of a mirror  212  may be anywhere between 16 square micrometers (μm 2 ) and 196 μm 2 , more preferably anywhere between 25 μm 2  and 100 μm 2 . More specifically, the shape of the mirror  212  and the pitch between the adjacent mirrors is arbitrary. 
         [0130]    In  FIG. 5 , the dotted line shows the deflection axis  212   a  for deflecting the mirror  212 . An incident light  511  emitted from a coherent light source  510  is incident along a perpendicular or diagonal direction relative to the deflection axis  212   a  of the mirror  212 . The light source  510  may be implemented with a laser light source to emit a coherent light. 
         [0131]    The following provides a description of the comprisal and operation of one pixel unit  211  with reference to the cross-sectional diagram thereof on the line II-II of the spatial light modulator  200  shown in  FIG. 5 . 
         [0132]      FIG. 4  is an outline diagram of a cross-section, viewed as indicated by the line II-II in  FIG. 5 , of one mirror element of the spatial light modulator. 
         [0133]    As shown in  FIGS. 2 and 3 , the spatial light modulator  200  in this embodiment includes a pixel array  210 , a bit line driver unit  220 , and a word line driver unit  230 . 
         [0134]    In the pixel array  210 , pixel units  211  are positioned in a grid where individual bit lines  221  extending vertically from the bit line driver unit  220  cross individual word lines  231  extending horizontally from the word line driver unit  230 . 
         [0135]    As shown in  FIG. 4 , each pixel unit  211  comprises a mirror  212  which tilts freely while supported on the substrate  214  by a hinge  213 . 
         [0136]    An OFF electrode  215  (and an OFF stopper  215   a ) and the ON electrode  216  (and an ON stopper  216   a ) are positioned symmetrically across the hinge  213  that comprises a hinge electrode  213   a  on the substrate  214 . 
         [0137]    When a predetermined voltage is applied to the OFF electrode  215 , it attracts the mirror  212  with a Coulomb force and tilts the mirror  212  so that it abuts the OFF stopper  215   a . This causes the incident light  511  to be reflected to the light path of an OFF position, which is not aligned with the optical axis of the projection optical system  130 . 
         [0138]    When a predetermined voltage is applied to the ON electrode  216 , it attracts the mirror  212  with a Coulomb force and tilts the mirror  212  so that it abuts the ON stopper  216   a . This causes the incident light  311  to be reflected to the light path of an ON position, which is aligned with the optical axis of the projection optical system  130 . 
         [0139]    An OFF capacitor  215   b  is connected to the OFF electrode  215  and to the bit line  221 - 1  by way of a gate transistor  215   c  that is constituted by a field effect transistor (FET) and the like. 
         [0140]    Further, an ON capacitor  216   b  is connected to the ON electrode  216 , and to the bit line  221 - 2  by way of a gate transistor  216   c , which is constituted by a field effect transistor (FET) and the like. The opening and closing of the gate transistor  215   c  and gate transistor  216   c  are controlled with the word line  231 . 
         [0141]    Specifically, one horizontal row of pixel units  211  that are lined up with an arbitrary word line  231  are simultaneously selected, and the charging and discharging of capacitance to and from the OFF capacitor  215   b  and ON capacitor  216   b  are controlled by way of the bit lines  221 - 1  and  221 - 2 , and thereby the individual ON/OFF controls of the micromirrors  212  of the respective pixel units  211  of one horizontal row are carried out. 
         [0142]    In other words, the OFF capacitor  215   b  and gate transistor  215   c  on the side of the OFF electrode  215  constitute a memory cell M 1  that is a so called DRAM structure. 
         [0143]    Likewise, the ON capacitor  216   b  and gate transistor  216   c  on the side of the ON electrode  216  constitute a DRAM-structured memory cell M 2 . 
         [0144]    With this configuration, the tilting operation of the mirror  212  is controlled in accordance with the presence and absence of writing data to the respective memory cells of the OFF electrode  215  and ON electrode  216 . 
         [0145]    As shown in  FIG. 2 , the light source  510  illuminates the spatial light modulator  200  with the incident light  511 , which is reflected by the individual micromirrors  212  as a reflection light  512 . The reflection light  512  then passes through a projection optical system  520  and is projected, as projection light  513 . 
         [0146]    A control apparatus  300 , according to the present embodiment, controlling the spatial light modulator  200  uses the ON/OFF states (i.e., an ON/OFF modulation) and oscillating state (i.e., an oscillation modulation) of the mirror  212 , thereby attaining an intermediate gray scale. 
         [0147]    A non-binary block  320  generates non-binary data  430  used for controlling the mirror  212  by converting an externally inputted binary video signal  400  into non-binary data. In this event, one LSB is different between the period of ON/OFF states of the mirror  212  and the period of intermediate oscillating state. 
         [0148]    A timing control unit  330  generates, on the basis of an input synchronous signal  410  (Sync), a drive timing  420  for the non-binary block  320 , a PWM drive timing  440 , and an OSC drive timing  441  for the mirror  212 . 
         [0149]    As shown in  FIG. 6 , the present embodiment is configured such that a desired number of bits of the upper bits  401  of the binary video image signal  400  is assigned to the ON/OFF control for the mirror and the remaining lower number of bits  402  is assigned to the oscillation control. 
         [0150]    Then, the control is such that the ON/OFF (positioning) state is controlled by the PWM drive timing  440  from the timing control unit  330  and the non-binary data  430 , while the oscillation state is controlled by the PWM drive timing  440  and OSC drive timing  441  from the timing control unit  330  and the non-binary data  430 . 
         [0151]    Next, the fundamental control for each mirror  212  of the spatial light modulator in this embodiment is described. 
         [0152]    More specifically, “Va (1, 0)” indicates an application of a predetermined voltage Va to the OFF electrode  215  and no application of voltage to the ON electrode  216  in the following description. 
         [0153]    Similarly, “Va (0, 1)” indicates no application of voltage to the OFF electrode  215  and an application of a voltage Va to the ON electrode  216 . 
         [0154]    “Va (0, 0)” indicates no application of voltage to either the OFF electrode  215  or ON electrode  216 . 
         [0155]    “Va (1, 1) indicates the application of a voltage Va to both the OFF electrode  215  and ON electrode  216 . 
         [0156]      FIGS. 7A ,  7 B,  7 C,  7 D,  7 E and  7 F show the configuration of the pixel unit  211  comprising the mirror  212 , hinge  213 , OFF electrode  215  and ON electrode  216 , and a basic example wherein the mirror  212  is controlled under an ON/OFF state and under an oscillating state 
         [0157]      FIG. 7A  shows the mirror  212  tilted from the neutral state to the ON state by being attracted to the ON electrode  216  as a result of applying a predetermined voltage (i.e., Va (0, 1)) to only the ON electrode  216 . In the ON state of the mirror  212 , the reflection light  512 , by way of the mirror  212 , is captured by the projection optical system  520  and projected as a projection light  513 .  FIG. 7B  shows the intensity of light projected in the ON state. 
         [0158]      FIG. 7C  shows the mirror  212  tilted from the neutral state to the OFF state by being attracted to the OFF electrode  215  as a result of applying a predetermined voltage (i.e., Va (1, 0)) to only the OFF electrode  215 . In the OFF state of the mirror  212 , the reflection light  512  is deflected from the projection optical system  520 , and therefore does not constitute a projection light  513 . The far right side of  FIG. 7B  shows the intensity of light projected in the OFF state.  FIG. 7D  shows the intensity of light projected in the OFF state. 
         [0159]      FIG. 7E  exemplifies a case of the mirror  212  performing a free oscillation in the maximum amplitude of A 0  between a tilted position (i.e., a Full ON) in contact with the ON electrode  216  and another tilted position (i.e., a Full OFF) in contact with the OFF electrode  215  (at Va (0, 0)). 
         [0160]    An incident light  511  is illuminated on the mirror  212  at a prescribed angle, and the intensity of light resulting from the incident light  511  reflecting in the ON direction and a portion of the light (i.e. the intensity of light of the reflection light  512 ) reflecting in a direction that is between the ON direction and OFF direction are incident to the projection optical system  520  so as to be projected as projection light  513 .  FIG. 7F  shows the intensity of light projected in an oscillating state. 
         [0161]    Specifically, in the ON state of the mirror  212  shown in  FIG. 7A , the flux of light of the reflected reflection light  512  is directed in the ON direction so as to be captured almost entirely by the projection optical system  520  and projected as the projection light  513 . 
         [0162]    In the OFF state of the mirror  212  shown in  FIG. 7C , the reflection light  512  is directed in an OFF direction away from the projection optical system  520 , and thus a light projected as a projection light  513  does not exist. 
         [0163]    In the oscillating state of the micromirror  212  shown in  FIG. 7E , a portion of the light flux of the reflection light  512 , diffraction light, diffusion light and the like are captured by the projection optical system  520  and projected as a projection light  513 . 
         [0164]    More specifically, the examples shown in  FIGS. 7A ,  7 B,  7 C,  7 D,  7 E and  7 F described above have been described for a case of applying the voltage Va represented by a binary value of “0” or “1” to each of the OFF electrode  215  and ON electrode  216 . Alternatively, a more minute control of the tilting angle of the mirror  212  is available by increasing the steps of the magnitude of Coulomb force generated between the mirror  212  and the OFF electrode  215  or ON electrode  216  by increasing the steps of the voltage values Va to multiple values. 
         [0165]    Furthermore, the examples shown in  FIGS. 7A ,  7 B,  7 C,  7 D,  7 E and  7 F described above have been described for a case of setting the mirror  212  (i.e., the hinge electrode  213   a ) at the ground potential. Alternatively, a more minute control of the tilting angle of the mirror  212  may also be achieved by applying an offset voltage thereto. 
         [0166]    A method for displaying a video image by using the projection device  100  in this embodiment is described below. 
         [0167]    When a binary video image signal  400  and a synchronization signal  410  are inputted into the control device  300 , the non-binary data  430 , the PWM driving timing  440  and the OSC driving timing  441  are generated. 
         [0168]    The non-binary block  320  and timing control unit  330  calculate, for each mirror of the SLM constituting a pixel of the video image of a frame, the period of time for controlling each mirror  212  under an ON state and under an oscillating state or the number of oscillations within one frame of a video image, in accordance with the binary video signal  400  and the drive timing  420  generated by the timing control unit  330  from the synchronous signal  410 . The non-binary block  320  and timing control unit  330  also generate non-binary data  430 , a PWM drive timing  440  and an OSC drive timing  441 . 
         [0169]    Specifically, the non-binary block  320  and timing control unit  330  that are comprised in the control apparatus  300  use the ratio of the intensity of a projection light  513  obtained by oscillating a predetermined mirror  212  in an oscillation time T to the intensity of a projection light  513  obtained by controlling the mirror  212  under an ON state during the oscillation time T, and calculate the period of time for controlling the mirror  212  under an ON state, the period of time for controlling the mirror  212  under the oscillating state or the number of oscillations during the period. 
         [0170]    The ON/OFF control and the oscillation control for each of the mirrors  212  configuring one frame of the video image are performed by using the non-binary data  430 , the PWM driving timing  440  and the OSC driving timing  441 , which are based on the calculated durations or the number of times of oscillation. 
         [0171]    Based on the above-described basic configuration, an example of the configuration of each pixel unit  211  of the pixel array  210  in the spatial light modulator  200  according to this embodiment is described with reference to  FIG. 8   
         [0172]    The pixel unit  211  having the configuration shown in  FIG. 8  is implemented by adding a second OFF electrode  236  (D) and a second ON electrode  235  (C), to the OFF and the ON sides, respectively, and by adding one plate line  232  (PL-n where “n” is the number of ROW lines) to each ROW line in the basic configuration shown in  FIG. 4 . 
         [0173]    The plate line  232  (PL- 2 ) is directly connected to the second ON electrode  235  (C 2 - 1 ) in the ROW line to which the plate line  232  (PL- 2 ) belongs, and also directly connected to the second OFF electrode  236  (D 1 - 1 ) in the ROW line (ROW- 1 ) adjacent to the ROW line (ROW- 2 ) to which the plate line  232  (PL- 2 ) belongs. 
         [0174]    Unlike the above described basic configuration, in addition to the potential control performed on the ON and the OFF sides by the word line  231  and the bit line  221 , the plate lines  232  can also applied to control the potential. 
         [0175]    Accordingly, potential control by the plate lines  232  may be performed while the mirror  212  is tilting between ON and OFF. This controls the mirror  212  to freely oscillate, with its tilting amplitude smaller than the maximum amplitude between ON and OFF. As a result, using the plate lines  232 , a higher gray scale, such as finer intermediate gray scale levels, can be implemented. 
         [0176]    Additionally, the plate lines  232  are controlled independent of the word lines  231  and the bit lines  221  in the embodiment shown in  FIG. 8 . Therefore, the potential control can be performed irrespective of the potentials of bit lines  221 . 
         [0177]    Furthermore, the electrodes on the ON and the OFF sides can be independently controlled by the plate lines  232 , whereby the ON and the OFF sides can be swapped and used depending on the placement direction of the light source. A control for the scanning direction of a plate line  232 , which will be described later, can be used. 
         [0178]    According to the conventional technique, to independently perform the potential control on the ON and the OFF side by using the plate lines  232 , a total of two plate lines  232  must be added to each ROW line. 
         [0179]    However, in this embodiment, the second OFF electrode  236  (D) and the second ON electrode  235  (C) can be independently controlled by adding as few as one plate line  232  to each ROW line, as will be described later. 
         [0180]    As a result, the number of plate lines  232  in a spatial light modulator  200  can be reduced by the total number of ROW lines (such as 1080 lines, etc.), in comparison with the conventional technology. With a reduction in the number of plate lines  232 , the space necessary for the configuration also decreases and a higher definition image with a higher gray scale can be projected using the plate lines  232 . 
         [0181]    Additionally, the space saved by reducing the plate lines  232  can be used to make the remaining plate lines  232  thicker. This increases the speed of the ON/OFF operations of the mirror by applying a higher potential to a plate line  232 , and by decreasing a floating capacitance of the plate line  232 , the operations can be more quickly and reliably implemented. 
         [0182]    The configuration shown in  FIG. 8  is schematically depicted to add one electrode to the ON and the OFF sides, respectively, and does not otherwise stipulate the positional relationship among the electrodes. 
         [0183]    The second ON electrode  235  (C) and the second OFF electrode  236  (D) may be arranged on the outer side of the ON electrode  216  (B) and the OFF electrode  215  (A), respectively. 
         [0184]    Alternately, the second ON electrode  235  (C) and the second OFF electrode  236  (D) may be arranged orthogonal to the deflection direction of the ON electrode  216  (B) and the OFF electrode  215  (A). 
         [0185]      FIG. 8  depicts a configuration with the second ON electrode  235  (C) and the second OFF electrode  236  (D) connected to different plate lines  232 . 
         [0186]    A plate line  232  may be connected to the second OFF electrode  236  (D) in the same ROW line instead of connecting to the second ON electrode  235  (C) in the same ROW line as that shown for the plate line  232 . In this case, the second ON electrode  235  (C) is connected to the plate line  232  of the adjacent ROW line. 
         [0187]    Additionally, an electrode in a ROW line located at a different ROW from a plate line  232  and connected to the plate line  232  can also be connected to an electrode not in an adjacent ROW line. For example, the plate line  232  (PL- 3 , not shown) may be connected to the second OFF electrode  236  (D 1 - 1 ) in the ROW line next to the adjacent line. 
         [0188]    Furthermore, one of two adjacent plate lines  232  may be connected to an electrode in the ROW line of the other plate line  232 . For example, the plate line  232  (PL- 1 ) is connected to the second ON electrode  235  (C) in the ROW line of the plate line  232  (PL- 1 ), and also connected to the second OFF electrode  236  (D) in the ROW line of the plate line  232  (PL- 2 ). Moreover, the plate line  232  (PL- 2 ) is connected to the second ON electrode  235  (C) in the ROW line of the plate line  232  (PL- 2 ), and also connected to the second OFF electrode  236  (D) in the ROW line of the plate line (PL- 1 ). 
         [0189]      FIGS. 9A ,  9 B and  9 C are schematic diagrams of exemplary embodiments of the layouts of the electrodes of pixel units  211  shown in  FIG. 8 . The common configuration of the layouts will be initially described with reference to  FIG. 9D .  FIG. 9D  shows an example of a cross section of the pixel unit, taken along the line IXC-IXC, of the layout shown in  FIG. 9C . 
         [0190]    As shown in  FIG. 9D , all of the layouts shown in  FIGS. 9A ,  9 B and  9 C are configurations wherein a hinge electrode  914  is arranged on the deflection axis  212   a , and an elastic hinge  911  supports the mirror  212  via a metal layer  912  on the upper surface of the hinge electrode  914 . Two electrodes are similarly arranged symmetrically about the hinge electrode  914 . The ON electrode  216  (B) and the second ON electrode  235  (C) are arranged on one side of the hinge electrode  914 , and the OFF electrode  215  (A) and the second OFF electrode  236  (D) are arranged on the other side. 
         [0191]      FIGS. 9A ,  9 B and  9 C show configurations obtained by varying the shapes and the sizes of the OFF electrode  215  (A), the ON electrode  216  (B), the second ON electrode  235  (C), and the second OFF electrode  236  (D). 
         [0192]    In  FIGS. 9A ,  9 B, and  9 C, the shape of the mirror  212  is represented with a dotted line in order to represent the positional relationship among the electrodes and the mirror  212 . The deflection axis  212   a  of the mirror is represented with a dashed vertical line. 
         [0193]    In the layout of  FIG. 9A , the ON electrode  216  (B) is arranged to enclose the three sides of the hinge electrode  914  on one side of the deflection axis  212   a , and the second ON electrode  235  (C) is arranged at the corner of the mirror to the right of the ON electrode  216  (B). Similarly, the OFF electrode  215  (A) is arranged to enclose the three sides of the hinge electrode  914  on the other side of the deflection axis  212   a , and the second OFF electrode  236  (D) is arranged at the corner of the mirror to the left of the OFF electrode  215  (A). The tips of the OFF electrode  215  (A) and the ON electrode  216  (B) are convex. These electrodes are designed so that when the mirror  212  is tilted to each side, it comes into contact with the convex protrusions of the OFF electrode  215  (A) and the ON electrode  216  (B), and the deflection angle of the mirror  212  is constant when the mirror  212  is deflected. 
         [0194]    In the layout shown in  FIG. 9A , the surface areas of the ON electrode  216  (B) and the OFF electrode  215 (A) are larger than the surface areas of the second ON electrode  235  (C) and the second OFF electrode  236  (D). This layout that can generate a sufficient Coulomb force even if relatively low voltages are applied to the ON electrode  216  (B) and the OFF electrode  215  (A). In contrast, the surface areas of the second ON electrode  235  (C) and the second OFF electrode  236  (D) are small. This reduces the voltage applied to the electrodes by making the necessary Coulomb force itself relatively low, according to the principle of leverage with the arrangement of the second ON electrode  235  (C) and the second OFF electrode  236  (D) in positions away from the hinge electrode  914 . 
         [0195]    In the layout shown in  FIG. 9B , the OFF electrode  215  (A), the ON electrode  216  (B), the second ON electrode  235  (C) and the second OFF electrode  236  (D) all have identical forms and are arranged around the hinge electrode  914 . Since the electrodes are formed into only one shape, the manufacturing process is simplified through design simplification, improvements in manufacturing yield, and cost. 
         [0196]      FIG. 9C  shows the layout wherein the second ON electrode  235  (C) and the second OFF electrode  236  (D) are arranged on the inside, and the OFF electrode  215  (A) and the ON electrode  216  (B) are arranged on the outside. The tips of the second ON electrode  235  (C) and the second OFF electrode  236  (D) arranged on the inside are convex. These electrodes are designed so that when the mirror  212  is tilted to each side, it comes into contact with the convex protrusions of the second ON electrode  235  (C) and the second OFF electrode  236  (D), and the deflection angle of the mirror  212  is constant when the mirror  212  is deflected. 
         [0197]    Since the OFF electrode  215  (A) and the ON electrode  216  (B), which are arranged on the outside, have larger surface areas, this layout offers an advantage in that lower voltages may be applied to the OFF electrode  215  (A) and the ON electrode  216  (B), as compared to those in the other layouts. 
         [0198]    The layouts shown in  FIGS. 9E and 9F  are configured with only the second ON electrode  235  (C) and the second OFF electrode  236  (D). 
         [0199]      FIG. 10  is a simplified diagram showing an example of the connections between the pixel units  211  and the plate lines  232 , which are shown in  FIG. 8 . The layout shown in  FIG. 10  is described with reference to the electrode layout shown in  FIG. 9A . However, the layout of the electrodes is not limited to this particular layout. 
         [0200]    As shown in  FIG. 10 , each of the plate lines  232  is connected to the electrodes of ROW lines on both sides of the plate line  232 . The plate line  232  is connected to the second OFF electrode  236  (D) in the ROW line on one side of the plate line  232  and to the second ON electrode  235  (C) in the ROW line on the other side of the plate line  232 . Specifically, one plate line  232  is simultaneously connected to the electrodes in two ROW lines. This means that two different ROW lines share one plate line  232 . 
         [0201]      FIGS. 11A ,  11 B and  11 C are cross-sectional views of the pixel unit  211  taken along the line IXA-IXA in the layout shown in  FIG. 9A . In this layout, the hinge electrode  914 , the ON electrode  216  (B) and the OFF electrode  215  (A) are arranged on the surface of a substrate  901 , whereas the second ON electrode  235  (C) and the second OFF electrode  236 (D) are buried in the substrate  901 . 
         [0202]      FIGS. 12A ,  12 B,  12 C and  12 D are functional circuit diagrams which correspond to the states shown in  FIGS. 11A ,  11 B and  11 C, respectively, in which voltages are applied to the bit lines  221 , the word line  231 , the plate lines  232  and the electrodes. 
         [0203]    An example of the operations of the pixel unit  211  having the configuration shown in  FIG. 8  is described below with reference to  FIGS. 11A ,  11 B,  11 C,  12 A,  12 B,  12 C and  12 D. 
         [0204]    The following is a description of the operations for changing the mirror  212  to the OFF state, which is shown in  FIG. 11A . 
         [0205]    As shown in  FIG. 12A , an H level (5V) is applied to the word line  231  while an H level (5V) and an L level (0V) are applied to the bit lines  221 - 1  and  221 - 2 , respectively. As a result, gate transistors  215   c  and  216   c  are turned on, and the potentials of the OFF electrode  215 (A) and the ON electrode  216  (B) become identical to the bit lines  221 - 1  and  221 - 2 , respectively. Specifically, 5V and 0V are respectively applied to the OFF electrode  215 (A) and the ON electrode  216  (B). 
         [0206]    Since the plate lines  232  (PL- 1 , PL- 2 ) remain at 0V, both the second ON electrode  235 (C) and the second OFF electrode  236 (D) are driven to 0V. As a result, a Coulomb force is generated only between the OFF electrode  215 (A), to which 5V is applied, and the mirror  212 . The mirror  212  is tilted by being drawn by the OFF electrode  215 (A) and changes to the OFF state, as shown in  FIG. 11A . 
         [0207]    The following is a description of the operations for changing the mirror  212  to the ON state, which is shown in  FIG. 11B . 
         [0208]    As shown in  FIG. 12B , the H level (5V) is applied to the word line  231  while the L level (0V) and the H level (5V) are applied to the bit lines  221 - 1  and  221 - 2 , respectively. As a result, the gate transistors  215   c  and  216   c  are turned on, and the potentials of the OFF electrode  215  (A) and the ON electrode  216  (B) become identical to the bit lines  221 - 1  and  221 - 2 , respectively. Specifically, 0V and 5V are respectively applied to the OFF electrode  215 (A) and the ON electrode  216  (B). Since the plate lines  232  (PL- 1 , PL- 2 ) remain at 0V, both the second ON electrode  235 (C) and the second OFF electrode  236 (D) are driven to 0V. As a result, a Coulomb force is generated only between the ON electrode  216 (B), to which 5V is applied, and the mirror  212 . The mirror  212  is tilted by being drawn by the ON electrode  216 (B) and changes to the ON state, as shown in  FIG. 11B . 
         [0209]    The following is a description of the operations for changing the mirror  212  to the intermediate oscillation state, which is shown  FIG. 11C . 
         [0210]    To cause the mirror  212  to make an intermediate oscillation, the H level (5V) is applied to the word line  231  while the L level (0V) is applied to both the bit lines  221 - 1  and  221 - 2 , as shown in  FIG. 12C . As a result, the gate transistors  215   c  and  216   c  are turned on, and the potentials of the OFF electrode  215  (A) and the ON electrode  216  (B) become identical to the bit lines  221 - 1  and  221 - 2 , respectively. Specifically, 0V is applied to both of the electrodes. Additionally, since the plate lines  232  (PL- 1 , PL- 2 ) remain at 0V, both the second ON electrode  235 (C) and the second OFF electrode  236 (D) are driven to 0V. As a result, no voltages are applied to the electrodes, and the mirror  212  tilts away from the ON electrode  216  by the restoring force of the elastic hinge  911  and starts to freely oscillate towards the OFF side. 
         [0211]    While the mirror  211  is tilting towards the OFF side with the free oscillation, the H level (10V) is applied to the plate line  232  (PL- 1 ), as shown in  FIG. 12D . At this time, the bit lines  221 - 1  and  221 - 2 , the word line  231 , and the plate line  232  (PL- 2 ) are at 0V. As a result, a Coulomb force is generated in a direction reverse to the direction in which the mirror  212  is moving, between the second ON electrode  235 (C), to which 10 V is applied, and the mirror  212 . This reduces the tilting force of the mirror  212  towards the OFF side. 
         [0212]    Furthermore, as shown in  FIG. 12C  when all of the electrodes are driven to 0V, the operation state is restored, by applying the L level to the plate line  232  (PL- 1 ) before the mirror  212  is prevented from tilting toward the OFF side by the Coulomb force generated between the second ON electrode  235  (C) and the mirror  212 . 
         [0213]    As a result, the mirror  212  changes to the intermediate oscillation state shown in  FIG. 11C  with an amplitude smaller than the maximum amplitude. 
         [0214]    The operations of the pixel unit  211  are described with the assumption that the H levels of the bit lines  221 - 1  and  221 - 2  and the word line  231  are 5V, and the H level of the plate line  232  is 10V. However, the applied voltages are not limited these specific values. The voltages may be adjusted according to the Coulomb force required by the weight of the mirror, the distance from the bary center to the rotational center, and the thickness, width, length, material, or the shape of the cross section of the elastic hinge. 
         [0215]    The change of the mirror  212  from the ON state to the intermediate oscillation state is illustrated as an example of operations. A change from the OFF state to the intermediate oscillation state can be similarly implemented by using the second OFF electrode  236  (D). 
         [0216]    The above described operation example refers to the change made to the intermediate oscillation state as an example of using the plate lines  232 . However, the usage of the plate lines  232  is not limited to this example. For example, the plate lines  232  can be used to assist change operations by temporarily applying a voltage equal to or higher than that applied from the bit line  221 - 1  or  221 - 2  at the start of a state change, (i.e., from the ON state to the OFF state, from the OFF state to the ON state, from the oscillation state to the ON state, from the oscillation state to the OFF state, etc.) 
         [0217]      FIG. 13A  shows an example of a layout of the configuration of the control circuit for the pixel array  210 , where the pixel units  211  shown in  FIG. 8  are arranged as an array. 
         [0218]    A plate line driver unit  250  for controlling the plate lines  232 , added to the basic configuration of the pixel array  21  shown in  FIG. 3 , is added. 
         [0219]    Specifically, the present embodiment is configured to add the plate line driver unit  250  in the vicinity of the pixel array  210 , in addition to the provision of the bit line driver part  220  and word line driver unit  230 . 
         [0220]    The word line driver unit  230  comprises a first address decoder  230   a  and a word line driver  230   b  that are used for selecting word lines  231  (WL). 
         [0221]    The plate line driver unit  250  comprises a plate line driver  251 , plate line address decoders  252 - 1  and  252 - 2 , all of which are used for selecting plate lines  232  (PL). 
         [0222]    Furthermore, the plate lines  232  are arranged so that the number of plate lines  232  is greater than the number of ROW lines by one line. The one extra plate line  232  is required to make the configurations of the pixel units  211  identical in the configuration according to this embodiment. 
         [0223]    Each pixel unit  211  is connected to the bit lines  221 - 1  and  221 - 2  of the bit line driver unit  220  (Bitline driver) so that data is written to the pixel units  211  belonging to the ROW line selected by a word line  231  (WL). 
         [0224]    A signal produced by an external input data though a serial word line (WL_ADDR  1 ) is connected in parallel to an address decoder  230   a  (WL Address Decoder). A word line driver  230   b  (WL Driver) converts the input data into a designated voltage and applies the voltage to the word line  231  (WL). 
         [0225]    In addition to the control processes carried out by the signals transmitted on the word line  231  (WL), the electrodes on the ON and the OFF sides of each of the pixel units  211  are also controlled by the plate line  232  (PL). For the plate lines  232  (PL), serial data PL_ADDRa and PL_ADDRb, provided from the plate line address generator  253  (PL Address Generator) are made parallel by a plate line address decoder  252 - 1  (PL Address Decoder-a) and a plate line address decoder  252 - 2  (PL Address Decoder-b). The data is converted into a necessary voltage by the plate line driver  251  (PL Driver). 
         [0226]    Here, the number of ROW lines can be set to, for example, 720 lines or more. 
         [0227]    In this case, data signals respectively inputted from the bit lines  221 - 1  and  221 - 2  to the memory cells M 1  and M 2  are transmitted to all memories in one ROW line within 23 nsec (nanoseconds). 
         [0228]    Namely, 720 ROW lines are processed by partitioning a display duration into four periods and assigning the four periods to the four colors of R, G, B and W, each of which has 256 gray scale levels, in 60 frames per second, 
         [0229]    1/60 sec/partitioned into 4/256 gray scale levels/720 lines=22.6 nsec 
         [0230]    Additionally, 1080 ROW lines are processed by partitioning a display duration into three periods and assigning the three periods to the three colors of R, G and B, each of which has 256 gray scale levels, in 60 frames per second, 
         [0231]    1/60/3/256/1080=20 nsec 
         [0232]      FIG. 13B  is a conceptual diagram showing an example of the internal configuration of the above described plate line address generator  253  (PL Address Generator) shown in  FIG. 13A . The plate line address generator  253  may be configured as part of the plate line driver unit  250 , as shown in  FIG. 13A , or as a module different from the module configuring the pixel array. 
         [0233]    Within the plate line address generator  253 , an increment counter  253   a , used when the scanning direction of the plate line  232  is a forward direction, and a decrement counter  253   b , used when the scanning direction of the plate line  232  is a reverse direction, are arranged along with a NOT circuit  253   c , AND circuits  253   d  and  253   e , and an OR circuit  253   f.    
         [0234]    The plate line address generator  253  can selectively output an address signal by using the increment counter  253   a  or the decrement counter  253   b  according to an externally inputted selection signal (Select). 
         [0235]    More specifically, the externally inputted selection signal (Select) is inputted to the AND circuits  253   d  and  253   e . However, since the signal input to the AND circuit  253   d  is inputted after being inverted by the NOT circuit  253   c , the externally inputted selection signal (Select) enables either the AND circuits  253   d  or the  253   e . Specifically, the AND circuit  253   d  is enabled when the selection signal (hereinafter referred to as a forward direction signal), which specifies the scanning direction of the plate line  232  to be the forward direction, is inputted, or the AND circuit  253   e  is enabled when the selection signal (hereinafter referred to as a reverse direction signal), which specifies the scanning direction of the plate line  232  to be the reverse direction, is inputted. 
         [0236]    As a result, an address signal (PL_ADDRx) is outputted from the OR circuit  253   f  on the basis of the address information of the plate line  232 , which is recorded in the increment counter  253   a , when the forward direction signal is inputted. 
         [0237]    Similarly, the address signal (PL_ADDRx) is outputted from the OR circuit  253   f  on the basis of the address information of the plate line  232 , which is recorded in the decrement counter  253   b , when the reverse direction signal is inputted. 
         [0238]      FIG. 14  shows an example of the internal configuration of the plate line address decoder  252 - 1  (PL Address Decoder-a) shown in  FIG. 13A . 
         [0239]    The plate line address decoder  252 - 1  comprises a serial-parallel conversion circuit  252   a  for serial-to-parallel converting an externally serially inputted address signal (PL_ADDRa) into the number of bits of the plate lines  232 , and an address detection unit constituted by EXOR circuits  252   b  and NOR circuits  252   c , all of which are equipped for the number of bits of the PL_ADDRa. 
         [0240]    An externally inputted address signal (PL_ADDRa) is serial-to-parallel converted by the serial-parallel conversion circuit  252   a  and is inputted in parallel to the respective EXOR circuits  252   b.    
         [0241]    If a plate line (PL) is the same as a plate line  232  (PL) selected by the parallel-converted value, the present PL is selected by the address detection unit (i.e., the EXOR circuit  252   b  and NOR circuit  252   c ) corresponding to the individual plate line  232 . 
         [0242]    Although not specifically shown in a drawing, the internal configurations of the plate line address decoder  252 - 2  (PL Address Decoder-b) and first address decoder  230   a  (WL Address Decoder) can be similar to that of the above described plate line address decoder  252 - 1 . 
         [0243]      FIG. 15  is a conceptual diagram showing an example of the internal configuration of the plate line driver  251  (PL Driver) shown in  FIG. 13A . 
         [0244]    The internal configuration of the plate line driver  251  (PL Driver) is comprised of circuits provided correspondingly to the plate lines  232  (PL). 
         [0245]    In the plate line driver  251 , an OR circuit  251   a  is equipped on the initial stage so as to enable either the plate line address decoder  252 - 1  (PL Address Decoder-a) or the plate line address decoder  252 - 2  (PL Address Decoder-b) to select a plate line  232  (PL). 
         [0246]    The output of the OR circuit  251   a  is inputted to the flip-flop  251   b  (Flip-Flop), and the output value is retained therein. 
         [0247]    Then, the output value is latched at the latch  251   c  (Latch) with a PL-CLK in order to synchronize with the bit line driver part  220  (Bitline driver). It is then converted by the level shift circuit  251   d  (Level shift) into the required voltage applied to the ON electrode  216 . 
         [0248]      FIG. 16  shows an example of the internal configuration of the bit line driver unit  220  (Bitline Driver) shown in  FIG. 13A . 
         [0249]    The bit line driver unit  220  in this embodiment includes a first stage latch  220   a , second stage latches  220   b , level shift circuits  220   c , third stage latches  220   d , inverters  220   e , and mode switches  220   f.    
         [0250]    The inverter  220   e  and mode changeover switch  220   f  function as column decoder for controlling the bit lines  221 - 1  and  221 - 2 . 
         [0251]    Specifically, the inverter  220   e  logically inverts the output (latch-out) from the third stage latch  220   d  to branch out as a bit line  221 - 1 , while the mode changeover switch  220   f  turns ON/OFF the latch-out output to the pre-branched bit line  221 - 2 . 
         [0252]    If one ROW is, for example, 1920 bits, the bit line driver part  220  receives an external input that is 15 times of 128-bit pixel data. 
         [0253]    The bit line driver part  220  latches this volume of data in three stages as follows: 
         [0254]    First stage: 128 latches (at the first stage latch  220   a ) 
         [0255]    ↓ 
         [0256]    Second stage: 640 latches (at the second stage latch  220   b ) 
         [0257]    ↓ 
         [0258]    Voltage conversion (level shift) (at the level shift circuit  220   c ) 
         [0259]    ↓ 
         [0260]    Third stage: 1920 latches (at the third stage latch  220   d ) 
         [0261]    The logic states of the bit lines  221 - 1  and  221 - 2  are decided according to a logic determined based on a table shown in  FIG. 17 , when the data is transmitted to the ON (bit line  221 - 2 ) side and the OFF (bit line  221 - 1 ) side of bit line after 1920 latches are made by the third stage latches  220   d , as described above. 
         [0262]      FIG. 18  is a timing chart showing the operational timings of &lt;pixel  1 - 1 &gt; (pixel unit  211 ) and &lt;pixel  2 - 1 &gt; (pixel unit  211 ), which share the plate line  232 , and the corresponding state of the mirror  212 , in the pixel array  210  shown in  FIG. 8 . 
         [0263]    The following descriptions of  FIG. 18  for using the plate lines  232  in different ROW lines provide one of the common characteristics of the spatial light modulator in this embodiment.  FIG. 18  shows the case where the plate line  232  is used to generate an intermediate oscillation, and the influence on &lt;pixel  1 - 1 &gt; (pixel unit  211 ) by the control of plate line  232  (PL- 2 ), which is used to generate the intermediate oscillation in &lt;pixel  2 - 1 &gt; (pixel unit  211 ). 
         [0264]    Additionally, the scanning directions of the word line  231  and the plate line  232  are assumed to be in a direction proceeding from larger to smaller numbers assigned to ROW lines (hereinafter referred to as the reverse direction). For example, ROW- 1081 , ROW- 1080 , ROW- 1079 , . . . , ROW- 3 , ROW- 2 , and ROW- 1  are sequentially accessed in this order. 
         [0265]    The scanning direction of the plate line  232  can be also controlled by the above described plate line address generator  253  having the internal configuration shown in  FIG. 13B . Moreover, a similar control can be performed for the word line  231  by providing an address generator having a configuration similar to the plate line address generator  253 , although this is not described here. 
         [0266]    As shown in  FIG. 18 , the two focused pixel units  211  (&lt;pixel  2 - 1 &gt; and &lt;pixel  1 - 1 &gt;) belong to different ROW lines. Therefore, a mode switch signal  221 - 3  (Intermediate) and the signals of the word line  231  and the plate line  232  of each pixel unit are different signals. However, only the effects of the control for the pixel unit  211  &lt;pixel  2 - 1 &gt; exerted on &lt;pixel  1 - 1 &gt; will be described here. Therefore, the mode switch signal  221 - 3  (Intermediate) and the signals of the word line  231  and the plate line  232  of &lt;pixel  1 - 1 &gt; are omitted. The bit lines  221  (the bit line  221 - 1 , the bit line  221 - 2 ) common to the two focused pixel units  211  are used, unlike the word line  231 , the plate line  232 , etc. However, since the ROW lines to which the pixel units  211  belong are different, different signals are provided at the timing when the word line  231  in each ROW line is sequentially accessed.  FIG. 18  illustrates the case where the same signal is. Therefore, the two focused pixel units  211  are displayed in gray. 
         [0267]    The following is a description of the operations of the pixel unit  211  &lt;pixel  2 - 1 &gt;. 
         [0268]    The signal of the word line  231  (WL- 2 ) operates at predetermined time intervals (in this case, the interval between control timings t 1  and t 4  is assumed to be one cycle) in order to control the selection of the bit lines  221 - 1  and  221 - 2 . 
         [0269]    In the meantime, the signal of the plate line  232  (PL- 2 ) starts to operate with a delay from the signal of the word line  231  (WL- 2 ) by an interval (between the control timings t 1  and t 2 ) that is shorter than one cycle of the signal of the word line  231  (WL- 2 ). In the example shown in  FIG. 18 , the signal of the plate line  232  operates two successive times during one cycle of the word line (WL- 2 ) (see the changes of the potential  232   a  that becomes ON with the pulse of the plate line address decoder  252 - 1  and becomes OFF with the pulse of the plate line address decoder  252 - 2 ). 
         [0270]    Accordingly, the transmission speed (frequency) of the signal in the plate line  232  (PL- 2 ) is faster than that of the signal in the word line  231  (WL- 2 ). 
         [0271]    The mirror  212  of &lt;pixel  2 - 1 &gt; stays stationary on the side of the ON electrode  216  (B 2 - 1 ) if LatchOUT (the output of the third stage latch  220   d ) is 1, or stays stationary on the side of the OFF electrode  215  (A 2 - 1 ) if the LatchOUT is 0 before the control timing t 1 , when the mode switch signal  221 - 3  (Intermediate) is “L”. Namely, the operations of the mirror  212  are controlled with pulse width modulation (PWM) like a PWM control profile  451  before the control timing t 1 . 
         [0272]    If LatchOUT is “1” at and after the control timing t 1  when the mode switch signal  221 - 3  (Intermediate) is “H”, the OFF electrode  215  (A 2 - 1 ) and the ON electrode  216  (B 2 - 1 ) are driven to 0V, and the mirror starts to freely oscillate as a result. 
         [0273]    As described above, the mode conversion between the pulse width modulation (PWM) and the intermediate oscillation (OSC) is controlled with the mode switch signal  221 - 3  (Intermediate). At control timing t 1  and after, there is a switch to the intermediate oscillation mode, when the signal of the word line  231  (WL- 2 ) is initially inputted after the mode switch signal  221 - 3  is driven to the H level. Before the control timing t 1 , there is a switch to the PWM mode. 
         [0274]    At the control timing t 2 , the plate line  232  (PL- 2 ) is selected by the plate line address decoder  252 - 1  (PL Address Decoder-a) and driven to the potential  232   a  of the H level. The plate line  232  (PL- 2 ) remains high until the selection of the plate line  232  (PL- 2 ) is cancelled by the plate line address decoder  252 - 2  (PL Address Decoder-b) at the control timing t 3 . 
         [0275]    Between control timing t 2  and control timing t 3 , during which the level of the plate line  232  (PL- 2 ) is high, the second ON electrode  235  (C 2 - 1 ) is driven to the potential  221   a  of H-level, and a Coulomb force is applied to the mirror  212  in the direction of the second ON electrode  235  (C 2 - 1 ). As a result, the intermediate oscillation (OSC) like an intermediate oscillation control profile  452  is generated. 
         [0276]    At the control timing t 5 , the OFF electrode  215  (A 2 - 1 ) is driven to the H level by the bit line  221 - 1  (Bitline). As a result, the mirror  212  is drawn by the OFF electrode  215  (A 2 - 1 ), changes from the intermediate oscillation state to the OFF state, and remains stationary. 
         [0277]    The following is a description of the operations of the pixel unit  211  &lt;pixel  1 - 1 &gt; with a focus on the effects the operations of the pixel unit  211  &lt;pixel  2 - 1 &gt;. 
         [0278]    The signal of the word line  231  (WL- 1 ) operates at predetermined time intervals similar to the word line  231  (WL- 2 ). However, the word line  231  (WL- 1 ) is sequentially accessed after the word line  231  (WL- 2 ), according to the above described scanning direction. Therefore, its signal is inputted with a delay from the signal of the word line  231  (WL- 2 ). Accordingly, the mirror  212  of &lt;pixel  1 - 1 &gt; starts an intermediate oscillation with a delay from the mirror  212  of &lt;pixel  2 - 1 &gt;, although the mirror  212  of &lt;pixel  1 - 1 &gt; has a control profile similar to &lt;pixel  2 - 1 &gt;. 
         [0279]    The potential  221   a  of the second OFF electrode  236  (D 1 - 1 ) in &lt;pixel  1 - 1 &gt;, which is generated by the voltage applied to the plate line  232  (PL- 2 ) in order to control &lt;pixel  2 - 1 &gt;, occurs while &lt;pixel  1 - 1 &gt; is in the PWM mode due to a delay of the sequential access to the word lines  231 . In this case, the mirror  212  of &lt;pixel  1 - 1 &gt; remains on the side of the ON electrode  216  (B 1 - 1 ) with the Coulomb force generated by the potential of the ON electrode  216  (B 1 - 1 ), as shown in  FIG. 18 . Accordingly, the mirror  212  of &lt;pixel  1 - 1 &gt; continues to stay on the side of the ON electrode  216  (B 1 - 1 ) because the Coulomb force generated between the second OFF electrode  236  (D 1 - 1 ) and the mirror  212  is temporary. 
         [0280]    In  FIG. 18 , the two focused pixel units  211  are displayed in gray. However, similar results can be obtained even if &lt;pixel  1 - 1 &gt; is displayed in another state. 
         [0281]    For example, if &lt;pixel  1 - 1 &gt; is displayed in black, the mirror  212  of &lt;pixel  1 - 1 &gt; remains on the side of the OFF electrode  215  (A 1 - 1 ) of &lt;pixel  1 - 1 &gt;, while the potential of the second OFF electrode  236  (D 1 - 1 ) in &lt;pixel  1 - 1 &gt; is the potential  221   a . Accordingly, the Coulomb force generated by the potential  221   a  of the second OFF electrode  236  (D 1 - 1 ) is applied in the direction of maintaining the stationary state. Therefore, the control operations of &lt;pixel  2 - 1 &gt; do not affect &lt;pixel  1 - 1 &gt;. 
         [0282]    More specifically, a delay of the sequential access to the word line  231  can also be adjusted by using the control for making a sequential access to the plate lines  232  while skipping them, which will be described later. As a result, the control for the intermediate oscillation by the plate line  232  can be more reliably performed. 
         [0283]      FIGS. 19A , through  19 D are charts showing various exemplary placements of a PWM control profile  451  (PWM drive timing  440 ) and an intermediate oscillation control profile  452  (OSC drive timing  441  in the mirror control profile  450 ) for one frame period of a mirror. 
         [0284]    The mirror control profile shown in  FIG. 19A  exemplifies the case of sequentially generating a PWM control profile  451  and an intermediate oscillation control profile  452  in the latter part of one frame. 
         [0285]      FIG. 19B  exemplifies the case of generating the PWM control profile  451  in the beginning of one frame and generating the intermediate oscillation control profile  452  towards the end of the same frame. 
         [0286]      FIG. 19C  exemplifies the case of generating the intermediate oscillation control profile  452  in the first half of one frame and then generating the PWM control profile  451 . 
         [0287]      FIG. 19D  exemplifies the case of generating the intermediate oscillation control profile  452  at the start of one frame and generating the PWM control profile  451  at the end thereof. 
         [0288]      FIG. 19E  exemplifies the case of aligning the ON position of the PWM control profile  451  with the beginning of one frame and aligning the end of the intermediate oscillation control profile  452  with the end of the same frame. 
         [0289]    The pattern (mirror control profile  450 ) of the behaviors of the mirror  212  in the aforementioned pixel units &lt;pixel  1 - 1 &gt; and &lt;pixel  2 - 1 &gt;), which are displayed in gray in  FIG. 18 , corresponds to  FIG. 19A . 
         [0290]    For any of the mirror control profiles  450  shown in  FIGS. 19A to 19D , the start timing of the intermediate oscillation control profile  452  is identified within one frame period. Therefore, sharing of a plate line  232  by different ROW lines in this embodiment can be implemented when the plate line  232  is controlled to generate the intermediate oscillation. 
         [0291]    Since the mirror  212  changes from the ON state to the intermediate oscillation state in the cases shown in  FIGS. 19A and 19D , the second ON electrode  235  (C) is used. Additionally, since the mirror  212  changes from the OFF state to the intermediate oscillation state in the cases shown in  FIGS. 19B and 19C , the second OFF electrode (D) is used. 
         [0292]      FIG. 20  is a functional circuit diagram showing a modification example of the pixel unit  211  described in  FIG. 8 . 
         [0293]    The modification example shown in  FIG. 20  represents the configuration in which one ON electrode  216  and one OFF electrode  215  are respectively arranged on the ON and the OFF sides. 
         [0294]    A plate line  232  is connected to the ON electrode  216 , which is arranged in the same ROW line as the plate line  232 , via a second ON capacitor  216   d  (Cap 3 ). The plate line  232  is also connected to the OFF electrode  215 , which is arranged in a ROW line different from the plate line  232 , via a second OFF capacitor  215   d  (Cap 4 ). 
         [0295]    This configuration enables the potential control for the ON and the OFF sides by using as few as one plate line  232  for each ROW line, in addition to the potential control using the word line  231  and the bit lined  221 . 
         [0296]      FIG. 21  is a schematic diagram for explaining an example of a layout of the electrodes in the pixel unit  211  shown in  FIG. 20 . 
         [0297]    On one side, the ON electrode  216  (B) is arranged to enclose the three sides of the hinge electrode  914  at the center of the deflection axis  212   a , represented with a vertical dashed line. The OFF electrode  215  (A) is similarly arranged to enclose the three sides of the hinge electrode  914  on the other side of the deflection axis  212   a.    
         [0298]    In this layout, the electrodes controlled with the word line  231  and the bit lines  221 , and the electrodes controlled with the plate line  232  are the same. Accordingly, the size of the electrodes can be increased, in comparison with the configuration shown in  FIG. 8 , thus a Coulomb force can be efficiently generated. 
         [0299]      FIG. 22  is a timing chart showing the operational timings of &lt;pixel  1 - 1 &gt; (pixel unit  211 ) and &lt;pixel  2 - 1 &gt; (pixel unit  211 ), which share the plate line  232  in the pixel array  210  with the configuration shown in  FIG. 20 , and the state of the mirror  212  corresponding to the timings is also described. Here, the effect on &lt;pixel  1 - 1 &gt;, when &lt;pixel  2 - 1 &gt; is controlled to make the intermediate oscillation by applying a voltage to the plate line  232 , is described. 
         [0300]    Additionally, the scanning directions of the word line  231  and the plate line  232  are assumed to be a direction (hereinafter referred to as the reverse direction) proceeding from larger to small numbers assigned to the ROW lines. For example, ROW- 1081 , ROW- 1080 , ROW- 1079 , . . . , ROW- 3 , ROW- 2 , ROW- 1  are sequentially accessed in this order. 
         [0301]    As shown in  FIG. 22 , the two focused pixel units  211  (&lt;pixel  2 - 1 &gt; and &lt;pixel  1 - 1 &gt;) are assumed to be displayed in gray. 
         [0302]    The following is a description of the operations of &lt;pixel  2 - 1 &gt;. 
         [0303]    Fundamentally, the operations are similar to those described in  FIG. 18 . However, since the plate line  232  (PL- 2 ) is connected to the ON electrode  216  (B 2 - 1 ) via the second ON capacitor  216   d , the voltage is applied to the ON electrode  216  (B 2 - 1 ) between control timing t 2  to control timing t 3 , and the ON electrode  216  (B 2 - 1 ) is therefore driven to the potential  221   a  of H level. As a result, the mirror  212  performs an intermediate oscillation (OSC), like the intermediate oscillation control profile  452 , with the Coulomb force generated between the ON electrode  216  (B 2 - 1 ) and the mirror  212 . 
         [0304]    The potential  221   a  of the ON electrode  216  (B 2 - 1 ) is determined by an applied voltage and the ratio of the capacitance of the ON capacitor  216   b  to that of the second ON capacitors  216   d.    
         [0305]    The following is a description of the operations of pixel unit  211 &lt;pixel  1 - 1 &gt; with a focus on the effects of the above described operations of pixel unit  211  &lt;pixel  2 - 1 &gt;. 
         [0306]    The operations of pixel unit  211  &lt;pixel  2 - 1 &gt; are fundamentally similar to those in the case shown in  FIG. 18 . However, the voltage applied to the plate line  232  (PL- 2 ) generates the potential  221   a  at the OFF electrode  215  (A 1 - 1 ) of &lt;pixel  1 - 1 &gt;. During this time, the mirror  212  of &lt;pixel  1 - 1 &gt; remains on the side of the ON electrode  216  (B 1 - 1 ) with a Coulomb force generated by the potential of the ON electrode  216  (B 1 - 1 ), as shown in  FIG. 22 . Accordingly, the mirror  212  of &lt;pixel  1 - 1 &gt; remains on the side of the ON electrode  216  (B 1 - 1 ) because the Coulomb force generated between the OFF electrode  215  (A 1 - 1 ) and the mirror  212  of &lt;pixel  1 - 1 &gt; is temporary. 
         [0307]    Similar results are obtained even if &lt;pixel  1 - 1 &gt; is displayed in another state. 
         [0308]    For example, if &lt;pixel  1 - 1 &gt; is displayed in black, the mirror  212  of &lt;pixel  1 - 1 &gt; remains on the side of the OFF electrode  215  (A 1 - 1 ) during the period in which the voltage is applied by the plate line  232  (PL- 2 ). Accordingly, the mirror  212  continues to stay on the side of the OFF electrode  215  (A 1 - 1 ) of &lt;pixel  1 - 1 &gt; even if the voltage is applied to the OFF electrode  215  (A 1 - 1 ) by the plate line  232  (PL- 2 ). Accordingly, the control operations for &lt;pixel  2 - 1 &gt; do not affect &lt;pixel  1 - 1 &gt;. 
         [0309]      FIG. 23  shows another modification example of the above described pixel unit  211  shown in  FIG. 8 . 
         [0310]      FIG. 23  shows the configuration obtained by omitting (from the configuration shown in  FIG. 20 ) the OFF capacitor  215   b  (Cap 1 ) and the ON capacitor  216   b  (Cap 2 ) from the sides of the OFF electrode  215  and the ON electrode  216 , respectively. However, the gate transistors  215   c  and  216   c  each have a floating capacitance Cf at their source terminals connected to the OFF electrode  215  and the ON electrode  216 , respectively, and the floating capacitance Cf achieves an effect similar to the omitted Cap 1  and Cap 2 . 
         [0311]    In this case, the capacitance of the second ON capacitor  216   d  is set almost equal to the capacitance of the OFF capacitor  215   b  (Cap 3 =Cap 1 ). Since the floating capacitance Cf is normally very small, Cap 3 &gt;&gt; Cf, and the potential of the ON electrode  216  becomes close to the voltage of the plate line  232  (PL). 
         [0312]    In the configuration shown in  FIG. 23 , the operational timings of &lt;pixel  1 - 1 &gt; (pixel unit  211 ) and &lt;pixel  2 - 1 &gt; (pixel unit  211 ), which share the plate line  232 , and the corresponding state of the mirror  212  are similar to the timing chart shown in  FIG. 22 . Therefore, further descriptions are omitted here. 
         [0313]      FIG. 24  shows a further modification example of the above described pixel unit  211  shown in  FIG. 8 . 
         [0314]    In the configuration shown in  FIG. 24 , an ON gate transistor  216   e  (and OFF gate transistor  215   e ) is arranged as a replacement for the second ON capacitor  216   d  (and second OFF capacitor  215   d ) in the pixel unit  211  shown in  FIG. 20 . Specifically, the plate line  232  is connected to the gate electrode of the ON gate transistor  216   e  (and OFF gate transistor  215   e ), and the application of a power supply voltage Vcc, to which the drain of the ON gate transistor  216   e  (and OFF gate transistor  215   e ) is connected, to the ON capacitor  216   b  (and OFF capacitor  215   b ) is controlled with the voltage applied from the plate line  232 . 
         [0315]      FIG. 25  is a timing chart showing the operational timings of &lt;pixel  1 - 1 &gt; (pixel unit  211 ) &lt;pixel  2 - 1 &gt; (pixel unit  211 ), which have the configuration including the ON gate transistor  216   e  (and OFF gate transistor  215   e ) and sharing the plate line  232 , and the corresponding state of the mirror  212 . 
         [0316]    Although the timings and the state of the mirror are fundamentally similar to the case of  FIG. 22 , there is a difference in that the potential  221   a  applied to the ON electrode  216 , according to the control for the plate line  232  (PL- 2 ), is determined not with the voltage of the plate line  232  (PL- 2 ) but with the power supply voltage Vcc connected to the drain of the ON gate transistor  216   e.    
         [0317]    Also the effects of the control for the plate line  232  on the pixel unit  211  &lt;pixel  1 - 1 &gt; is similar to that in the case of  FIG. 22 . 
         [0318]      FIG. 26  shows a further modification example of the pixel unit  211  shown in  FIG. 8 . This figure shows a configuration in which an ON diode  216   f  is arranged as a replacement for the second ON capacitor  216   d  (Cap 3 ) on the ON side in the configuration of the modification example shown in  FIG. 20 . Also on the OFF side, an OFF diode  215   f  is arranged as a replacement for the second OFF capacitor  215   d  (Cap 4 ). 
         [0319]    Operations of &lt;pixel  2 - 1 &gt; and &lt;pixel  1 - 1 &gt; are described with reference to  FIG. 27 . 
         [0320]    The control example shown in  FIG. 27  is different from the control example of  FIG. 25  in that the potentials of the ON electrode  216  (B 2 - 1 ) and the OFF electrode  215  (A 1 - 1 ) at the control timing t 3  are discharged by the bit lines  221 - 2  (bitline) and  221 - 1  (bitline) and the word line  231  (WL- 2 ) (see the waveform at the control timing t 3  in the word line  231 ). 
         [0321]    Accordingly, only one PL Address Decoder  252 - 1  (plate line address decoder  252 - 1 , plate line address decoder  252 - 2 ) is sufficient. An example of the layout of the control circuit in the periphery of the pixel array  210  in this case is shown in  FIG. 28 . 
         [0322]    As shown in  FIG. 28 , this is a simpler configuration in which one plate line address decoder  252  is connected to the plate line driver  251  instead of the two plate line address decoders  252 - 1  and  252 - 2  shown in  FIG. 13A . 
         [0323]    Namely, in this configuration, the word lines  231  (WL- 1 , WL- 2 ) are operated to discharge the voltage applied by the plate line  232  (PL- 2 ) via the ON diode  216   f , in addition to periodical operation at predetermined time intervals. 
         [0324]    Furthermore, the voltage of the pixel unit  211  &lt;pixel  1 - 1 &gt; can also be discharged by the operations of the word line (WL- 1 ) that are performed at predetermined time intervals depending on conditions such as the size of the applied potential  221   a , etc. 
         [0325]    In this case, the voltage that the plate line  232  (PL- 2 ) applies to the OFF electrode  215  (A 1 - 1 ) of &lt;pixel  1 - 1 &gt; at the control timing t 2  is discharged at the initial control timing t 6 , which occurs at predetermined time intervals in the word line  231  (WL- 1 ) after the control timing t 2 . Accordingly, the voltage is applied to both of the OFF electrode  215  (A 1 - 1 ) and the ON electrode (B 1 - 1 ) from the control timing t 2  to the control timing t 6  in the pixel unit  211  &lt;pixel  1 - 1 &gt;. However, since the mirror  212  of &lt;pixel  1 - 1 &gt; remains stationary on the side of the ON electrode  216  at the control timing t 2 , a relatively high Coulomb force is applied between the ON electrode  216  and the mirror  212 . If the Coulomb force applied between the mirror  212  and the ON electrode  216  of &lt;pixel  1 - 1 &gt; is higher than the Coulomb force applied between the mirror  212  and the OFF electrode  215  of &lt;pixel  1 - 1 &gt; and the restoring force of the elastic hinge  911 , the mirror  212  of &lt;pixel  1 - 1 &gt; will remain on the side of the ON electrode  216  (B 1 - 1 ) for the duration of control timing t 2  to control timing t 6 . 
         [0326]    By using the control for making a sequential access while also skipping the plate lines  232 , which will be described later, a delay of the sequential access to the word lines  231  is adjusted. Consequently, the interval from the control timing t 2  to the control timing t 6  can be adjusted. As a result, the above described operations can be performed more reliably. 
         [0327]      FIG. 29  shows a further modification example of the pixel unit  211  shown in  FIG. 8 . There are a total of four bit lines; specifically, two bit lines  221  (bit line  221 - 1   a , bit line  221 - 2   b ), the only difference being the applied voltages, are provided on the ON side, and two bit lines  221  (bit line  221 - 2   a , bit line  221 - 2   b ), the only difference being the applied voltages, are provided on the OFF side. 
         [0328]      FIG. 29  shows the configuration where the drain of the ON gate transistor  216   e  (OFF gate transistor  215   e ) is connected to the added bit lines  221  (bit line  221 - 1   b . The bit line  221 - 2   b ) replaces the power supply voltage Vcc in the configuration of the modification example shown in  FIG. 24 . 
         [0329]    From the two bit lines  221  provided on the ON side, identical signals, which only vary in terms of H-level voltage differences, are outputted. The two bit lines  221  provided on the OFF side operate in a similar manner. Accordingly, the above described bit line driver unit  220  shown in  FIG. 13A  can be replaced with a 5V bit line driver unit  220   g  and a 10V bit line driver unit  220   h , which are shown in  FIG. 30 . The internal configurations of the 5V bit line driver unit  220   g  and the 10V bit line driver unit  220   h  are similar to that of the bit line driver unit  220  shown in  FIG. 16 . However, the only difference is that voltages converted by the level shift circuit  220   c  are 5V and 10V, respectively. 
         [0330]    As a result, the two bit lines, in which the only difference is the voltage, are provided on the ON and the OFF sides of each pixel unit  211 . 
         [0331]      FIG. 31  is a timing chart showing the operational timings of &lt;pixel  2 - 1 &gt; (pixel unit  211 ) and the state of the mirror  212  in the configuration shown in  FIG. 29 . In  FIG. 31 , the plate line  232  is used to change the mirror  212  from the oscillation state to the stationary state. 
         [0332]    Before the control timing t 1 , when the mode switch signal  221 - 3  (Intermediate) is “L”, both of the two bit lines  221  on the ON side are “1” and both of the two bit lines  221  on the OFF side are “0” if LatchOUT is 1. As a result, the mirror  212  remains on the side of the ON electrode  216  (B 2 - 1 ). In contrast, if LatchOUT is “0”, both of the two bit lines  221  on the OFF side are “1” and both of the two bit lines  221  on the ON side are “0”. As a result, the mirror  212  remains on the side of the OFF electrode  215  (A 2 - 1 ). Specifically, before the control timing t 1 , the operations of the mirror  212  are controlled like the PWM control profile  451  with the pulse width modulation (PWM). 
         [0333]    At and after the control timing t 1 , when the mode switch signal  221 - 3  (intermediate) is “H”, all of the bit lines  221  on the ON and the OFF sides are 0, and the OFF electrode  215  (A 2 - 1 ) and the ON electrode  216  (B 2 - 1 ) are driven to 0V if LatchOUT is “1”. As a result, the mirror  212  starts to freely oscillate. 
         [0334]    Thereafter, at the control timing t 5 , the plate line address decoder  252 - 1  (PL Address Decoder-a) and the plate line address decoder  252 - 2  (PL Address Decoder-b) are sequentially selected synchronously with the operations of the word line  231  (WL- 2 ). 
         [0335]    As a result, the plate line  232  (PL- 2 ) operates and the OFF gate transistor  215   e  is opened, whereby the potential of the OFF electrode  215  (A 2 - 1 ) becomes the same as the bit line  221 - 1   b , to which the higher voltage is applied. Moreover, the ON electrode  216  is driven to 0V because both of the two connected bit lines  221  (bit line  221 - 2   a , bit line  221 - 2   b ) are 0V. 
         [0336]    Consequently, it becomes possible to switch the mirror  212  more quickly towards the OFF electrode  215  with a higher Coulomb force, as compared with the case of operating only with the word line  213  (WL- 2 ). As a result, the state change time is reduced, and a more ideal gray scale level can be represented. 
         [0337]      FIG. 32  is a conceptual diagram showing the state where the sequential access to the plate lines  232  is controlled. This figure shows the state where the sequential access is made to the plate lines  232  while skipping two lines. 
         [0338]    By performing the above described sequential access control, the effects on other ROW lines, which accompany the selection of a plate line  232  in this embodiment, can be more reliably avoided, as will be described later. 
         [0339]      FIG. 32  shows an example in which the plate lines  232  are used to generate the intermediate oscillation. A pulse signal  252 - 3  represents a signal for selecting a plate line  232 . The pulse signal  252 - 3  is composed of a selection start signal  252 - 1   a , outputted from the plate line address decoder  252 - 1  shown in  FIG. 13A , and a selection cancel signal  252 - 2   a , outputted from the plate line address decoder  252 - 2  shown in  FIG. 13A . 
         [0340]    In  FIG. 32 , the selection start signal  252 - 1   a  and the selection cancel signal  252 - 2   a  are depicted for each plate line  232 , and the timing differences of pulse signals  252 - 3  inputted to the plate lines  232  are also depicted. 
         [0341]    Specifically, after an access is made to an arbitrary plate line  232  (PL-n), the access is made to the plate lines  232  by skipping every two lines such as plate line  232  (PL-n+3) and plate line  232  (PL-n+6). 
         [0342]    As a result, a higher gray scale and a higher definition image can be projected by implementing the diverse operations of the mirror  212  with signals applied to the plate lines  232 , without being restricted by the cycle of access to the memory cells M 1  and M 2  of each pixel unit  211 . 
         [0343]      FIG. 33  is a flowchart showing an example of the sequential access control for the plate lines in the spatial light modulator comprising the display system, according to the embodiment of the present invention. 
         [0344]    A process for the sequential access control is invoked by externally inputting a binary video image signal  400 . This access control is performed by the control device  300 . 
         [0345]    Initially, in step S 10 , the type of the binary video image signal  400  is analyzed. Whether the binary video image signal  400  is an interlaced signal or a progressive signal is determined based on the analysis result in step S 20 . 
         [0346]    If the binary video image signal  400  is determined to be the interlaced signal in step S 20 , the process proceeds to step S 30 , in which the number of skip lines N is set to the number of skip lines Ni (Ni is an integer equal to or larger than 1) of the plate lines  232 , which is optimized for the interlaced signal. 
         [0347]    With the interlaced signal, in order to reproduce one binary video image signal  400 , even-numbered fields obtained by collecting remaining even-numbered ROW lines are scanned after all the odd-numbered fields obtained by collecting odd-numbered ROW lines are scanned. 
         [0348]    This causes a significant difference between the scanning timings of adjacent ROW lines, and the even-numbered ROW lines are scanned with a sufficient delay from the odd-numbered ROW lines. 
         [0349]    Because of this, the PWM mode may be applied to an adjacent ROW line if a plate line  232  is used to generate the intermediate oscillation in the configuration in which, as in this embodiment, the plate line  232  is shared by adjacent ROW lines. 
         [0350]    Accordingly, the number of skip lines N may be set to 1, the original number of skip lines of an interlaced signal. As a result, the effect on other ROW lines can be more reliably prevented. 
         [0351]    Alternately, the number of skip lines N may be set to an odd number other than 1. 
         [0352]    If the binary video image signal  400  is determined to be the progressive signal in step S 20 , the process proceeds to step S 40 , in which the number of skip lines N is set to the number of skip lines Np (an integer equal to or larger than 0) of the plate lines  232 , which is optimized for the progressive signal. 
         [0353]    With the progressive signal, the ROW lines are sequentially scanned without being skipped in order to reproduce one binary video image signal  400 . 
         [0354]    Since the scanning timing of an adjacent ROW line is delayed, the PWM mode may be applied to the adjacent ROW line. Accordingly, the number of skip lines N is normally set to 0. However, if the above described delay is not sufficient, the number of skip lines N, which causes the PWM mode to be executed for an adjacent ROW line, is set. 
         [0355]    In step S 50 , the pulse signal  252 - 3  that instructs the timing of an access to the plate line  232  waits to be inputted. 
         [0356]    In step S 60 , the sequential access is made to the plate lines  232 , while skipping the plate lines  232  by the number of skip lines N set in step S 30  or S 40 . 
         [0357]    If the sequential access reaches the plate line  232  that cannot be skipped any more, a similar sequential access is made after shifting the plate line  232  to be scanned from the scanned plate line  232  by one line. 
         [0358]    The variables are internally used to manage the plate lines  232  to be sequentially accessed. However, the above described variables may be separately controlled for the case where the pulse signal  252 - 3  is the selection start signal  252 - 1   a  and the case where the pulse signal  252 - 3  is the selection cancel signal  252 - 2   a , resulting in mutually independent sequential access controls for the plate lines  232 . 
         [0359]    In step S 70 , it is determined whether or not a series of pulse signals  252 - 3  for the binary video image signal  400  has been inputted. 
         [0360]    If the determination result in step S 70  is “NO”, the process proceeds to step S 50 , in which the sequential access is continuously made by waiting for the next pulse signal  252 - 3  to be inputted. 
         [0361]    If the determination result in step S 70  is “YES”, the process proceeds to step S 80 , in which the sequential access control process is terminated. 
         [0362]    By performing the above described sequential access control, the effects on other ROW lines, which accompany the selection of a plate line  232  shared by a plurality of ROW lines as in this embodiment, can be more reliably prevented. 
         [0363]    Additionally, the sequential access control can handle the binary video image signal  400 , whether it is an interlaced signal or a progressive signal. 
         [0364]    The above described sequential access control for the plate lines  232 , skipping the plate lines by a predetermined number, has another advantage in that the sequential access control itself for the plate lines  232  is simplified. 
         [0365]    In the example shown in  FIG. 32 , the sequential access for inputting the selection cancel signal  252 - 2   a  occurs after the scanning of the sequential access of one time for inputting the selection start signal  252 - 1   a  is terminated. Accordingly, a complicated control process, for example, when one signal starts to scan while another signal is under the scanning process, can be avoided. This can be implemented because the scanning of the sequential access can be terminated within the short interval after the selection start signal  252 - 1   a  is inputted to the time when the selection cancel signal  252 - 2   a  is inputted. This can be realized by changing the number of the skip-lines N. 
         [0366]      FIG. 34  is a functional block diagram showing the configuration of a projection device including the spatial light modulator according to an embodiment of the present invention. As shown in  FIG. 34 , the projection device  5010  according to this embodiment includes a spatial light modulator  5100  (spatial light modulator  200 ), a control unit  5500  (control device  300 ), a TIR (Total Internal Reflection) prism  5300 , a projection optics system  5400 , and a light source optics system  5200 . The projection apparatus  5010  is a so-called single-panel projection apparatus  5010  comprising a single spatial light modulator  5100 . 
         [0367]    The spatial light modulator  5100  is configured with the above described spatial light modulator  200  having the plate lines  232 . 
         [0368]    The projection optical system  5400  is equipped with the spatial light modulator  5100  and TIR prism  5300  in the optical axis of the projection optical system  5400 , and the light source optical system  5200  is equipped in such a manner that the optical axis matches that of the projection optical system  5400 . 
         [0369]    The TIR prism  5300  causes the illumination light  5600 , incoming from the light source optical system  5200  placed onto the side, to enter the spatial light modulator  5100  at a prescribed inclination angle as incident light  5601  and causes a reflection light  5602 , reflected by the spatial light modulator  5100 , to transmit to the projection optical system  5400 . 
         [0370]    The projection optical system  5400  projects the reflection light  5602  as projection light  5603  to a screen  5900 . 
         [0371]    The light source optical system  5200  comprises a variable light source  5210  for generating the illumination light  5600 , a condenser lens  5220  for focusing the illumination light  5600 , a rod type condenser body  5230 , and a condenser lens  5240 , all of which are sequentially placed in the aforementioned order in the optical axis of the illumination light  5600 , which is emitted from the variable light source  5210  and incident to the side face of the TIR prism  5300 . 
         [0372]    The projection apparatus  5010  employs a single spatial light modulator  5100  for implementing a color display on the screen  5900  by means of a sequential color display method. 
         [0373]    Specifically, the variable light source  5210 , comprising a red laser light source  5211 , a green laser light source  5212  and a blue laser light source  5213  (which are not shown in the drawing), allows independent controls for the light emission states and divides one frame of display data into a plurality of sub-fields (i.e., three sub-fields, that is, red (R), green (G) and blue (B) in the present case). It further causes each of the red  5211 , green  5212  and blue  5213  laser light sources to emit each respective light in a time series at the time band corresponding to the sub-field of each color. 
         [0374]      FIG. 35  is a functional block diagram showing an example of the configuration of the control unit  5500  in the above described projection device  5010 . This control unit  5500  includes a frame memory  5520 , an SLM controller  5530 , a sequencer  5540 , a video image analyzing unit  5550 , a light source controlling unit  5560 , and a light source driving circuit  5570 . 
         [0375]    The sequencer  5540  is configured with a microprocessor and controls the operational timings of the entire control unit  5500  and the spatial light modulator  5100 . 
         [0376]    The frame memory  5520  holds an input image signal  5700  (binary video image signal  400 ) of, for example, one frame, inputted from an external device (not shown) and connected to a video image signal input unit  5510 . The input image signal  5700  is updated each time one frame has been displayed. 
         [0377]    The SLM controller  5530  processes the input image signal  5700  read from the frame memory  5520 , partitions the signal into a plurality of subfields, and outputs the partitioned data to the spatial light modulator  5100  as control data for implementing the ON/OFF control and the oscillation control for a mirror  5112  of the spatial light modulator  5100 . The control data also includes the control data of the plate line  232  on the basis of the type  5800  of the input image signal  5700 . 
         [0378]    The sequencer  5540  outputs a timing signal- to the spatial light modulator  5100  in synchronization with the generation of data in the SLM controller  5530 . 
         [0379]    The video image analyzing unit  5550  outputs a video image analysis signal  6800  for generating diverse light source pulse patterns on the basis of the input image signal  5700  inputted from the video image signal input unit  5510 , and notifies the SLM controller  5530  of the type  5800  of the input image signal  5700 . 
         [0380]    The light source controlling unit  5560  controls operations for emitting the illumination light  5600 , which are performed by the variable light source  5210 , via the light source driving circuit  5570  on the basis of the video image analysis signal  6800  obtained from the video image analyzing unit  5550  via the sequencer  5540 . 
         [0381]    The light source driving circuit  5570  drives the red laser light source  5211 , the green laser light source  5212 , and the blue laser light source  5213  of the variable light source  5210  to emit light according to an instruction issued from the light source controlling unit  5560 . 
         [0382]    According to the present invention, the projection technique, which uses the spatial light modulator element, for achieving both of a higher gray scale and a higher definition of a projected image can be provided without increasing the number of wires.