Patent Grant
7916381
1. Technical Field
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.
2. Description of the Related Art
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.
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
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.
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
Specifically,
The control circuit positions the micro-mirrors to be at either an ON or an OFF angular orientation, as that shown in
For example, assuming n bits of gray scales, one time frame is divided into 2n−1 equal time periods. For a 16.7-millisecond frame period and n-bit intensity values, the time period is 16.7/(2n−1) milliseconds.
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 2n−1 time periods. Each pixel'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's eye integrates the pixel brightness so that the image appears the same as if it were generated with analog levels of light.
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.
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.
However, in the gray scale control by the pulse width modulation (PWM), as shown in
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
An eighth embodiment of the present invention provides the spatial light modulator according to the first embodiment, comprising a mirror device.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
A thirtieth embodiment of the present invention provides the spatial light modulator according to the seventeenth embodiment, comprises a mirror device.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Preferred embodiments according to the present invention are described in detail below with reference to the drawings.
An example of the basic configuration of a projection device 100 in the embodiment is initially described, and the embodiments are described thereafter.
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.
As shown in
The mirror 212 of one pixel unit 211 is controlled by applying a voltage to an address electrode placed on the substrate 214.
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.
Specifically, the area size of a mirror 212 may be anywhere between 16 square micrometers (μm2) and 196 μm2, more preferably anywhere between 25 μm2 and 100 μm2. More specifically, the shape of the mirror 212 and the pitch between the adjacent mirrors is arbitrary.
In
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
As shown in
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.
As shown in
An OFF electrode 215 (and an OFF stopper 215a) and the ON electrode 216 (and an ON stopper 216a) are positioned symmetrically across the hinge 213 that comprises a hinge electrode 213a on the substrate 214.
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 215a. 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.
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 216a. 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.
An OFF capacitor 215b is connected to the OFF electrode 215 and to the bit line 221-1 by way of a gate transistor 215c that is constituted by a field effect transistor (FET) and the like.
Further, an ON capacitor 216b is connected to the ON electrode 216, and to the bit line 221-2 by way of a gate transistor 216c, which is constituted by a field effect transistor (FET) and the like. The opening and closing of the gate transistor 215c and gate transistor 216c are controlled with the word line 231.
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 215b and ON capacitor 216b 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.
In other words, the OFF capacitor 215b and gate transistor 215c on the side of the OFF electrode 215 constitute a memory cell M1 that is a so called DRAM structure.
Likewise, the ON capacitor 216b and gate transistor 216c on the side of the ON electrode 216 constitute a DRAM-structured memory cell M2.
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.
As shown in
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.
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.
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.
As shown in
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.
Next, the fundamental control for each mirror 212 of the spatial light modulator in this embodiment is described.
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.
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.
“Va (0, 0)” indicates no application of voltage to either the OFF electrode 215 or ON electrode 216.
“Va (1, 1) indicates the application of a voltage Va to both the OFF electrode 215 and ON electrode 216.
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.
Specifically, in the ON state of the mirror 212 shown in
In the OFF state of the mirror 212 shown in
In the oscillating state of the micromirror 212 shown in
More specifically, the examples shown in
Furthermore, the examples shown in
A method for displaying a video image by using the projection device 100 in this embodiment is described below.
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.
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.
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.
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.
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
The pixel unit 211 having the configuration shown in
The plate line 232 (PL-2) is directly connected to the second ON electrode 235 (C2-1) in the ROW line to which the plate line 232 (PL-2) belongs, and also directly connected to the second OFF electrode 236 (D1-1) in the ROW line (ROW-1) adjacent to the ROW line (ROW-2) to which the plate line 232 (PL-2) belongs.
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.
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.
Additionally, the plate lines 232 are controlled independent of the word lines 231 and the bit lines 221 in the embodiment shown in
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.
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.
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.
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.
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.
The configuration shown in
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.
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).
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.
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 (D1-1) in the ROW line next to the adjacent line.
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).
As shown in
In
In the layout of
In the layout shown in
In the layout shown in
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.
The layouts shown in
As shown in
An example of the operations of the pixel unit 211 having the configuration shown in
The following is a description of the operations for changing the mirror 212 to the OFF state, which is shown in
As shown in
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
The following is a description of the operations for changing the mirror 212 to the ON state, which is shown in
As shown in
The following is a description of the operations for changing the mirror 212 to the intermediate oscillation state, which is shown
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
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
Furthermore, as shown in
As a result, the mirror 212 changes to the intermediate oscillation state shown in
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.
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).
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.)
A plate line driver unit 250 for controlling the plate lines 232, added to the basic configuration of the pixel array 21 shown in
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.
The word line driver unit 230 comprises a first address decoder 230a and a word line driver 230b that are used for selecting word lines 231 (WL).
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).
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.
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).
A signal produced by an external input data though a serial word line (WL_ADDR 1) is connected in parallel to an address decoder 230a (WL Address Decoder). A word line driver 230b (WL Driver) converts the input data into a designated voltage and applies the voltage to the word line 231 (WL).
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).
Here, the number of ROW lines can be set to, for example, 720 lines or more.
In this case, data signals respectively inputted from the bit lines 221-1 and 221-2 to the memory cells M1 and M2 are transmitted to all memories in one ROW line within 23 nsec (nanoseconds).
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,
1/60 sec/partitioned into 4/256 gray scale levels/720 lines=22.6 nsec
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,
1/60/3/256/1080=20 nsec
Within the plate line address generator 253, an increment counter 253a, used when the scanning direction of the plate line 232 is a forward direction, and a decrement counter 253b, used when the scanning direction of the plate line 232 is a reverse direction, are arranged along with a NOT circuit 253c, AND circuits 253d and 253e, and an OR circuit 253f.
The plate line address generator 253 can selectively output an address signal by using the increment counter 253a or the decrement counter 253b according to an externally inputted selection signal (Select).
More specifically, the externally inputted selection signal (Select) is inputted to the AND circuits 253d and 253e. However, since the signal input to the AND circuit 253d is inputted after being inverted by the NOT circuit 253c, the externally inputted selection signal (Select) enables either the AND circuits 253d or the 253e. Specifically, the AND circuit 253d 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 253e 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.
As a result, an address signal (PL_ADDRx) is outputted from the OR circuit 253f on the basis of the address information of the plate line 232, which is recorded in the increment counter 253a, when the forward direction signal is inputted.
Similarly, the address signal (PL_ADDRx) is outputted from the OR circuit 253f on the basis of the address information of the plate line 232, which is recorded in the decrement counter 253b, when the reverse direction signal is inputted.
The plate line address decoder 252-1 comprises a serial-parallel conversion circuit 252a 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 252b and NOR circuits 252c, all of which are equipped for the number of bits of the PL_ADDRa.
An externally inputted address signal (PL_ADDRa) is serial-to-parallel converted by the serial-parallel conversion circuit 252a and is inputted in parallel to the respective EXOR circuits 252b.
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 252b and NOR circuit 252c) corresponding to the individual plate line 232.
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 230a (WL Address Decoder) can be similar to that of the above described plate line address decoder 252-1.
The internal configuration of the plate line driver 251 (PL Driver) is comprised of circuits provided correspondingly to the plate lines 232 (PL).
In the plate line driver 251, an OR circuit 251a 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).
The output of the OR circuit 251a is inputted to the flip-flop 251b (Flip-Flop), and the output value is retained therein.
Then, the output value is latched at the latch 251c (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 251d (Level shift) into the required voltage applied to the ON electrode 216.
The bit line driver unit 220 in this embodiment includes a first stage latch 220a, second stage latches 220b, level shift circuits 220c, third stage latches 220d, inverters 220e, and mode switches 220f.
The inverter 220e and mode changeover switch 220f function as column decoder for controlling the bit lines 221-1 and 221-2.
Specifically, the inverter 220e logically inverts the output (latch-out) from the third stage latch 220d to branch out as a bit line 221-1, while the mode changeover switch 220f turns ON/OFF the latch-out output to the pre-branched bit line 221-2.
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.
The bit line driver part 220 latches this volume of data in three stages as follows:
First stage: 128 latches (at the first stage latch 220a)
↓
Second stage: 640 latches (at the second stage latch 220b)
↓
Voltage conversion (level shift) (at the level shift circuit 220c)
↓
Third stage: 1920 latches (at the third stage latch 220d)
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
The following descriptions of
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.
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
As shown in
The following is a description of the operations of the pixel unit 211 <pixel 2-1>.
The signal of the word line 231 (WL-2) operates at predetermined time intervals (in this case, the interval between control timings t1 and t4 is assumed to be one cycle) in order to control the selection of the bit lines 221-1 and 221-2.
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 t1 and t2) that is shorter than one cycle of the signal of the word line 231 (WL-2). In the example shown in
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).
The mirror 212 of <pixel 2-1> stays stationary on the side of the ON electrode 216 (B2-1) if LatchOUT (the output of the third stage latch 220d) is 1, or stays stationary on the side of the OFF electrode 215 (A2-1) if the LatchOUT is 0 before the control timing t1, 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 t1.
If LatchOUT is “1” at and after the control timing t1 when the mode switch signal 221-3 (Intermediate) is “H”, the OFF electrode 215 (A2-1) and the ON electrode 216 (B2-1) are driven to 0V, and the mirror starts to freely oscillate as a result.
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 t1 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 t1, there is a switch to the PWM mode.
At the control timing t2, 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 232a 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 t3.
Between control timing t2 and control timing t3, during which the level of the plate line 232 (PL-2) is high, the second ON electrode 235 (C2-1) is driven to the potential 221a of H-level, and a Coulomb force is applied to the mirror 212 in the direction of the second ON electrode 235 (C2-1). As a result, the intermediate oscillation (OSC) like an intermediate oscillation control profile 452 is generated.
At the control timing t5, the OFF electrode 215 (A2-1) 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 (A2-1), changes from the intermediate oscillation state to the OFF state, and remains stationary.
The following is a description of the operations of the pixel unit 211 <pixel 1-1> with a focus on the effects the operations of the pixel unit 211 <pixel 2-1>.
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 <pixel 1-1> starts an intermediate oscillation with a delay from the mirror 212 of <pixel 2-1>, although the mirror 212 of <pixel 1-1> has a control profile similar to <pixel 2-1>.
The potential 221a of the second OFF electrode 236 (D1-1) in <pixel 1-1>, which is generated by the voltage applied to the plate line 232 (PL-2) in order to control <pixel 2-1>, occurs while <pixel 1-1> 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 <pixel 1-1> remains on the side of the ON electrode 216 (B1-1) with the Coulomb force generated by the potential of the ON electrode 216 (B1-1), as shown in
In
For example, if <pixel 1-1> is displayed in black, the mirror 212 of <pixel 1-1> remains on the side of the OFF electrode 215 (A1-1) of <pixel 1-1>, while the potential of the second OFF electrode 236 (D1-1) in <pixel 1-1> is the potential 221a. Accordingly, the Coulomb force generated by the potential 221a of the second OFF electrode 236 (D1-1) is applied in the direction of maintaining the stationary state. Therefore, the control operations of <pixel 2-1> do not affect <pixel 1-1>.
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.
The mirror control profile shown in
The pattern (mirror control profile 450) of the behaviors of the mirror 212 in the aforementioned pixel units <pixel 1-1> and <pixel 2-1>), which are displayed in gray in
For any of the mirror control profiles 450 shown in
Since the mirror 212 changes from the ON state to the intermediate oscillation state in the cases shown in
The modification example shown in
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 216d (Cap3). 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 215d (Cap4).
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.
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 212a, 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 212a.
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
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.
As shown in
The following is a description of the operations of <pixel 2-1>.
Fundamentally, the operations are similar to those described in
The potential 221a of the ON electrode 216 (B2-1) is determined by an applied voltage and the ratio of the capacitance of the ON capacitor 216b to that of the second ON capacitors 216d.
The following is a description of the operations of pixel unit 211<pixel 1-1> with a focus on the effects of the above described operations of pixel unit 211 <pixel 2-1>.
The operations of pixel unit 211 <pixel 2-1> are fundamentally similar to those in the case shown in
Similar results are obtained even if <pixel 1-1> is displayed in another state.
For example, if <pixel 1-1> is displayed in black, the mirror 212 of <pixel 1-1> remains on the side of the OFF electrode 215 (A1-1) 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 (A1-1) of <pixel 1-1> even if the voltage is applied to the OFF electrode 215 (A1-1) by the plate line 232 (PL-2). Accordingly, the control operations for <pixel 2-1> do not affect <pixel 1-1>.
In this case, the capacitance of the second ON capacitor 216d is set almost equal to the capacitance of the OFF capacitor 215b (Cap3=Cap1). Since the floating capacitance Cf is normally very small, Cap3>> Cf, and the potential of the ON electrode 216 becomes close to the voltage of the plate line 232 (PL).
In the configuration shown in
In the configuration shown in
Although the timings and the state of the mirror are fundamentally similar to the case of
Also the effects of the control for the plate line 232 on the pixel unit 211 <pixel 1-1> is similar to that in the case of
Operations of <pixel 2-1> and <pixel 1-1> are described with reference to
The control example shown in
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
As shown in
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 216f, in addition to periodical operation at predetermined time intervals.
Furthermore, the voltage of the pixel unit 211 <pixel 1-1> 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 221a, etc.
In this case, the voltage that the plate line 232 (PL-2) applies to the OFF electrode 215 (A1-1) of <pixel 1-1> at the control timing t2 is discharged at the initial control timing t6, which occurs at predetermined time intervals in the word line 231 (WL-1) after the control timing t2. Accordingly, the voltage is applied to both of the OFF electrode 215 (A1-1) and the ON electrode (B1-1) from the control timing t2 to the control timing t6 in the pixel unit 211 <pixel 1-1>. However, since the mirror 212 of <pixel 1-1> remains stationary on the side of the ON electrode 216 at the control timing t2, 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 <pixel 1-1> is higher than the Coulomb force applied between the mirror 212 and the OFF electrode 215 of <pixel 1-1> and the restoring force of the elastic hinge 911, the mirror 212 of <pixel 1-1> will remain on the side of the ON electrode 216 (B1-1) for the duration of control timing t2 to control timing t6.
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 t2 to the control timing t6 can be adjusted. As a result, the above described operations can be performed more reliably.
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
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.
Before the control timing t1, 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 (B2-1). 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 (A2-1). Specifically, before the control timing t1, the operations of the mirror 212 are controlled like the PWM control profile 451 with the pulse width modulation (PWM).
At and after the control timing t1, 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 (A2-1) and the ON electrode 216 (B2-1) are driven to 0V if LatchOUT is “1”. As a result, the mirror 212 starts to freely oscillate.
Thereafter, at the control timing t5, 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).
As a result, the plate line 232 (PL-2) operates and the OFF gate transistor 215e is opened, whereby the potential of the OFF electrode 215 (A2-1) becomes the same as the bit line 221-1b, 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 221-2a, bit line 221-2b) are 0V.
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.
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.
In
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).
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 M1 and M2 of each pixel unit 211.
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.
Initially, in step S10, 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 S20.
If the binary video image signal 400 is determined to be the interlaced signal in step S20, the process proceeds to step S30, 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.
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.
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.
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.
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.
Alternately, the number of skip lines N may be set to an odd number other than 1.
If the binary video image signal 400 is determined to be the progressive signal in step S20, the process proceeds to step S40, 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.
With the progressive signal, the ROW lines are sequentially scanned without being skipped in order to reproduce one binary video image signal 400.
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.
In step S50, the pulse signal 252-3 that instructs the timing of an access to the plate line 232 waits to be inputted.
In step S60, 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 S30 or S40.
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.
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 252-1a and the case where the pulse signal 252-3 is the selection cancel signal 252-2a, resulting in mutually independent sequential access controls for the plate lines 232.
In step S70, it is determined whether or not a series of pulse signals 252-3 for the binary video image signal 400 has been inputted.
If the determination result in step S70 is “NO”, the process proceeds to step S50, in which the sequential access is continuously made by waiting for the next pulse signal 252-3 to be inputted.
If the determination result in step S70 is “YES”, the process proceeds to step S80, in which the sequential access control process is terminated.
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.
Additionally, the sequential access control can handle the binary video image signal 400, whether it is an interlaced signal or a progressive signal.
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.
In the example shown in
The spatial light modulator 5100 is configured with the above described spatial light modulator 200 having the plate lines 232.
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.
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.
The projection optical system 5400 projects the reflection light 5602 as projection light 5603 to a screen 5900.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 now abandoned. The application Ser. No. 11/121,543 is a Continuation In Part (CIP) Application of three previously filed Applications. These three Applications are Ser. No. 10/698,620 filed on Nov. 1, 2003, now abandoned Ser. No. 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.
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| Number | Date | Country | |
|---|---|---|---|
| 20090207165 A1 | Aug 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61069454 | Mar 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12291922 | Nov 2008 | US |
| Child | 12381812 | US | |
| Parent | 12074033 | Mar 2008 | US |
| Child | 12291922 | US | |
| Parent | 11121543 | May 2005 | US |
| Child | 12074033 | US | |
| Parent | 10698620 | Nov 2003 | US |
| Child | 11121543 | US | |
| Parent | 10698620 | US | |
| Child | 11121543 | US | |
| Parent | 10699140 | Nov 2003 | US |
| Child | 10698620 | US | |
| Parent | 10699143 | Nov 2003 | US |
| Child | 10699140 | US |
