JP2005221564A - Image display device, driving circuit, method for controlling light transmissivity of display element and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving circuit capable of preventing the component cost and the mounting cost from increasing by making a D/A converter which operates at a high speed and has a high resolution and an amplifier which has a broad band region and high precision unnecessary, and to provide an image display device and method having the driving circuit. <P>SOLUTION: The driving circuit is provided with an image data forming means 11 of forming pixel data of (n) bits corresponding to respective pixels, an analog voltage generating means 12 of generating an analog lamp wave of which the voltage is changed periodically in a prescribed range, a digital signal producing means 13 of producing a digital signal of (n) bits according to the voltage value of analog lamp wave, a comparator 14 which compares the pixel data with the digital signal and a gamma correction means which supplies the voltage value of the analog lamp wave in accordance with the timing when the pixel data and the digital signal are in accord with each other to the corresponding pixels and displays a desired image and, at the same time, performs the gamma correction of pixel data in accordance with a voltage-transmissivity characteristic in synchronization with the timing when the digital signal value of the driving circuit of the image display device is switched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image display device including an image display element having pixels for displaying an image corresponding to a supplied voltage value, a drive circuit, a method for controlling the light transmittance of the display element, and a program therefor, in particular, the image display element. The present invention relates to an image display device having a gamma correction function, a drive circuit, a light transmittance control method for a display element, and a program thereof.

  A liquid crystal display element using liquid crystal is generally used as an image display element having a plurality of pixels for displaying an image in accordance with a supplied voltage value.

Various systems have been proposed as drive circuits for liquid crystal display elements. As an example,
(1) image data generating means for generating pixel data corresponding to each pixel of the liquid crystal display element;
(2) analog voltage generating means for generating an analog ramp wave whose voltage value periodically changes within a predetermined range;
(3) Digital signal generating means for generating an n-bit digital signal corresponding to the voltage value of the analog ramp wave;
(4) a comparator for comparing each pixel data with the digital signal;
Japanese Patent No. 3045266 discloses a driving circuit that displays a desired image by supplying a voltage value of an analog ramp wave to a corresponding pixel in accordance with the timing at which pixel data and a digital signal match. Is disclosed.

  On the other hand, a liquid crystal display element usually has a desired characteristic because the relationship between the display luminance (T; synonymous with the light transmittance of liquid crystal) and the VT characteristic is nonlinear with respect to the supplied voltage value (V). Therefore, a so-called gamma correction function is required. An example of the V-T characteristic is shown in FIG. As can be seen from this figure, even if the voltage applied to the liquid crystal is changed from zero to V1, V2,... At equal intervals, the corresponding light transmittances T0, T1,.

In the above prior art, as a gamma correction method, the analog ramp wave is corrected according to the VT characteristic of the liquid crystal. Specific means is shown in FIG.
In FIG. 11, a comparison counter clock CCLK derived from a timing generation circuit and a start pulse Sp output every horizontal period are supplied to an n-bit counter circuit. This n-bit counter circuit derives count outputs Q0... Qn (n bits) and inputs them to the memory address of the next stage. The memory is a data table, and the data contents are values corresponding to the correction curves of the gamma correction in the order of the addresses. Accordingly, the data output of the memory is corrected by the correction curve of the gamma correction, and the data output subjected to the gamma correction is supplied as the data input of the D / A converter. Here, the correction data is m-bit data larger than n. As a result, the output of the D / A converter changes at the step of the comparison counter clock CCLK, and a conversion analog input signal Ta having a correction curve for gamma correction in one horizontal period is generated. Accordingly, if the analog ramp wave has a correction curve as shown in V of FIG. 12 for the liquid crystal pixel as shown in FIG. 10, the light transmission changes linearly with respect to the pixel data as shown in T of FIG. Rate characteristics are obtained.
Japanese Patent No. 3045266

However, in such a method, a voltage waveform that is nonlinear and requires extremely high voltage accuracy at each timing must be transmitted to the liquid crystal display element.
(1) A high-speed, high-resolution D / A converter and a broadband, high-accuracy amplifier are required, resulting in high component costs.
(2) High-quality design with a wide band and low noise is also required in the transmission path, and the component cost and mounting cost increase.
As a whole, there is a problem that it becomes a high-cost drive circuit.

  An object of the present invention is to solve the problems of the prior art as described above, and to provide an image display device or a drive circuit for the image display device that can perform gamma correction with low cost and high accuracy. That is, the analog ramp wave is a simple waveform and is subjected to gamma correction by digital control, thereby reducing the components and mounting costs related to the generation and transmission of the analog ramp wave.

  That is, the present invention has been made in view of the above-described problems of the prior art, and provides an image display apparatus capable of performing gamma correction with high accuracy at low cost and a drive circuit used in the apparatus. In other words, for the purpose of reducing the cost of mounting components related to the generation of an analog lamp wave for emitting an analog lamp as a light source and the transmission of image light including image light or irradiation light emitted from the lamp. Yes.

Another object of the present invention is to provide specific means for controlling the timing for switching the value of the digital signal in the gamma correction means. Furthermore, it aims at providing the specific waveform suitable for the above-mentioned analog ramp wave.
For example, in an image display element using liquid crystal, the optimum drive voltage range may be different for each element. The object of the present invention is to provide a means for always obtaining an optimum gamma characteristic. Furthermore, the present invention provides an image display device having a suitable configuration, and a large-screen image display device capable of obtaining a high gradation display quality that is gamma-corrected with low cost and high accuracy using the image display device. It is intended to provide.

  The present invention further provides a large-screen image display capable of obtaining a high gradation display quality with high-precision gamma correction at a low cost and capable of displaying a high-resolution image by using the above-described image display device. The object is to provide a device. A further object of the present invention is to provide a large-screen color image display device that can obtain high gradation display quality that has been subjected to gamma correction at a low cost and with high accuracy using the image display device.

  According to a first aspect of the present invention, there is provided an image display device driving circuit comprising: image data generating means for generating n-bit pixel data corresponding to each pixel; and an analog ramp wave whose voltage value periodically varies within a predetermined range. An analog voltage generating means for generating; a digital signal generating means for generating an n-bit digital signal corresponding to the voltage value of the analog ramp wave; and a comparator for comparing the pixel data with the digital signal. The analog ramp wave voltage value corresponding to the timing at which the digital signal coincides with the corresponding pixel is supplied to the corresponding pixel to synchronize with the timing at which the digital signal value of the drive circuit of the image display device is switched. And gamma correction means for performing gamma correction of the pixel data in accordance with the voltage / transmittance characteristics of each pixel. The features.

  According to a second aspect of the present invention, in the first aspect, the gamma correction unit generates a pulse signal whose rising or falling transition or both occurrence timings change according to the voltage / transmittance characteristics of each pixel. It is characterized by comprising a pulse signal generating means and an n-bit first counter for counting rising or falling transitions or both of the pulse signal, and using the output of the counter as the digital signal.

  According to a third aspect of the present invention, in the second aspect, the pulse signal generation means loads a gamma correction data storage means for storing gamma correction data and counts a clock signal having a predetermined frequency by loading the gamma correction data. And a second counter that outputs a signal that causes a transition after a count number corresponding to the loaded gamma correction data, wherein the output signal of the second counter is used as the pulse signal.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the analog ramp wave includes a time region in which the voltage value changes linearly with time for each period. .

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the apparatus includes a voltage adjusting unit that varies a predetermined voltage range of the analog ramp wave.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the digital signal device further comprises timing adjusting means for adjusting a timing at which the value of the digital signal is switched.

  The image display device according to claim 7 generates an image display element having a plurality of pixels for displaying an image according to a supplied voltage value and n-bit pixel data corresponding to each of the plurality of pixels. Image data generating means, analog voltage generating means for generating an analog ramp wave whose voltage value periodically changes within a predetermined range, and digital for generating an n-bit digital signal corresponding to the voltage value of the analog ramp wave A signal generation unit; and a comparator that compares the pixel data with the digital signal, and supplies the voltage value of the analog ramp wave corresponding to the timing at which the pixel data matches the digital signal to the corresponding pixel. The voltage / transmittance characteristics of each pixel are synchronized with the timing at which the value of the digital signal of the image display device for displaying a desired image is switched. Characterized by comprising a gamma correction means for performing gamma correction of the pixel data corresponding to.

  According to an eighth aspect of the present invention, in the seventh aspect, the gamma correction unit generates a pulse signal in which a rising or falling transition or both occurrence timings change according to a voltage / transmittance characteristic of each pixel. It is characterized by comprising a pulse signal generating means and an n-bit first counter for counting rising or falling transitions or both of the pulse signal, and using the output of the counter as the digital signal.

  The invention according to claim 9 is the invention according to claim 7, wherein the pulse signal generation means counts clock signals having a predetermined frequency by loading the gamma correction data storage means for storing gamma correction data and loading the gamma correction data. A second counter that outputs a signal that causes a transition after a count number corresponding to the loaded gamma correction data is provided, and an output signal of the second counter is used as the pulse signal.

  A tenth aspect of the present invention is characterized in that, in any one of the seventh to ninth aspects, the analog ramp wave includes a time region in which the voltage value linearly changes with time in one period. .

  An eleventh aspect of the invention is characterized in that, in any one of the seventh to tenth aspects, voltage adjusting means for changing a predetermined voltage range of the analog ramp wave is provided.

  A twelfth aspect of the invention is characterized in that in any one of the seventh to eleventh aspects, a timing adjustment means for adjusting a timing at which the value of the digital signal is switched is provided.

  A thirteenth aspect of the present invention is the liquid crystal display according to any one of the seventh to twelfth aspects, wherein the image display device is an LCOS (Liquid Crystal) in which a display unit including a liquid crystal layer and an electrode for driving the liquid crystal layer is formed on a silicon backplane. On Silicon) is an image display element formed in an element shape.

  The invention according to claim 14 is the image display device according to any one of claims 1 to 13, an illumination device that is a light source for illuminating the image display element of the image display device, and an output from the image display element. An optical device for enlarging / reducing the incident light and projecting the light onto the projection surface, and expanding and / or reducing and projecting the emitted light from the image display element, which is spatially light-modulated based on the pixel data, onto the projection surface; An image is formed.

  According to a fifteenth aspect of the present invention, in the fourteenth aspect, the image data generation unit divides a display image for one frame into a plurality of subframe images, and sequentially subdivides each subframe for output. A data generation unit is provided, and an image pattern that is time-divisionally projected for each subframe is synthesized on the projection surface to display the image for one frame.

  According to a sixteenth aspect of the present invention, in the fourteenth or fifteenth aspect, the sub-frame image data generating means outputs corresponding pixel data with a pixel arrangement selected from the display image for one frame as one sub-frame, and The optical device includes optical path deflecting means for deflecting the optical path of the outgoing light from the image display element, and controls the deflection state of the optical path of the outgoing light that has been spatially light modulated by the image display element, corresponding to the subframe. The display position is shifted on the projection surface to display an image, and an image simulated to have a number of pixels substantially larger than the number of pixels of the image display element is displayed.

  In accordance with a seventeenth aspect of the present invention, in any one of the fourteenth to sixteenth aspects, the sub-frame image data generation means associates the display image for one frame as one sub-frame for each color, and stores pixel data. The illumination device includes a color separation element that separates light from the light source into a predetermined color and sequentially enters the image display element, and spatial light modulation is performed for each subframe corresponding to the color of the incident light. The emitted light is synthesized on the projection surface to display a color image.

  An invention of a method for controlling light transmittance of a display element according to claim 18 uses an image display device to change pixel data corresponding to each pixel and light transmittance of the display element in the image display device. Synchronizing with a digital signal corresponding to an analog ramp wave for the purpose, including a portion in which the voltage is linearly changed for each period period which is one horizontal scanning period of the analog ramp wave Features.

  According to a nineteenth aspect of the present invention, there is provided a method for controlling a light transmittance of a display element, wherein an analog ramp wave is formed in synchronization with a clock signal obtained from a digital ramp signal in the order of output of pixel data.

  The invention according to claim 20 corresponds to pixel data corresponding to each pixel by the image display device and an analog ramp wave for changing the light transmittance of the display element in the image display device. In synchronization with the digital signal, the light transmittance of the display element is controlled by including a portion in which the voltage is linearly changed for each period period which is one horizontal scanning period of the analog ramp wave. It is a program for.

  According to the present invention, in an image display device or a drive circuit for displaying a desired image by supplying a voltage value of an analog ramp wave corresponding to a timing at which pixel data and a digital signal coincide with each other to a corresponding pixel, gamma is obtained by digital control. Since the correction is performed, an expensive D / A converter or amplifier is not required, and the design and mounting cost of the signal transmission system is reduced, so that an image display device or an image that can perform gamma correction with high accuracy at low cost. A drive circuit for the display device is realized.

In the present invention, the analog ramp wave is changed linearly with time in one period of the analog ramp wave, so that the analog voltage generation circuit can be made low-cost by using a simple integration circuit or the like. Can be realized.
Further, according to the present invention, since the adjusting means for obtaining the optimum gamma characteristic is provided for each element even when the optimum driving voltage range is different for each element, a versatile driving circuit can be easily realized.

  Further, since the present invention uses LCOS in which a display unit including a liquid crystal layer and an electrode for driving the liquid crystal layer is formed on the silicon backplane as the image display element, pulse signal generation means that requires high-speed operation on the silicon backplane. By configuring a comparator or the like, finer gamma correction can be easily realized.

Further, according to the present invention, by using the image display device, a projection image display device capable of displaying a large screen with high image quality by low-cost and high-precision gamma correction is realized.
Further, according to the present invention, the display image for one frame is divided into a plurality of sub-frame images, and the time-division display is sequentially performed for each sub-frame, so that the total number of components can be reduced and the projection can be performed at a lower cost. An image display device is realized.

In the projection image display apparatus according to the present invention, since the optical path deflecting unit is provided to display an image having an apparently larger number of pixels than the number of pixels of the image display element, high gradation display with high-precision gamma correction is performed. An extremely high-quality projected image display device with high quality and high resolution is realized.
Further, according to the present invention, since one frame is displayed in a time-division manner for each color in the projection image display device, high gradation display quality with high precision gamma correction can be obtained and color projection image display at a lower cost can be achieved. A device is realized.

  Hereinafter, the present invention will be described in more detail by way of embodiments with reference to the drawings.

[Embodiment 1] (Claims 1, 4, 7, and 10)
FIG. 1 is a diagram schematically showing an example of the configuration of an image display device and its drive circuit according to the present invention. FIG. 2 is a timing chart showing an example of the operation.
As shown in FIG. 1, in the first embodiment, as a drive circuit of an image display device, an image data generation circuit 11 that is an image data generation unit, an analog voltage generation circuit 12 that is an analog voltage generation unit, and a digital signal generation It has a digital signal generation circuit 13 as means, and a comparator that compares pixel data with a digital signal.

Here, in FIG. 1, the image display element has a resolution of the number N of scanning lines in the vertical direction of the screen and the number of pixels M for each scanning line. The image data generation circuit outputs pixel data for one scanning line as a signal Dx for one horizontal scanning period. For example, if the pixels located on the L (1 ≦ L ≦ N) th scanning line are P _{1, L} , P _{2, L} ,..., P _{M, L} , pixel data (pixel data signal) corresponding to each pixel As shown in FIG. 1, D _{1, L} , D _{2, L} ,..., D _{M, L} are sequentially output in synchronization with the synchronization signal HCK. Here, one horizontal scanning period refers to one period of the horizontal synchronization signal HD (a period from the rising of the first pulse shown in FIG. 1 to the rising of the next pulse).

The shift register 15 sequentially captures the pixel data signals D1 _{, L} , D2 _{, L} ,..., DM _{, L} based on the synchronization signal HCK. The latch circuit 16 takes in all the outputs of the shift register 15 that are all pixel data for one scanning line at the same time at the rising edge (rising transition timing) of the horizontal synchronization signal HD, and outputs it to the comparator 14.

  The digital signal generation circuit 13 outputs a control signal CEN, an n-bit digital signal DRMP, and a DRMP synchronization signal CCK. As shown in FIG. 2, the signal DRMP and the synchronization signal CCK are signals whose periods change with time.

  The comparator 14 compares all the pixel data from the latch circuit 16 with the signal DRMP when the control signal CEN is at “H” (High) level. The comparator 14 also has outputs S1 to SM corresponding to the respective pixel data from the latch circuit 16, and outputs the output corresponding to the pixel data whose value matches the value of the signal DRMP to the falling (falling transition) of the synchronization signal CCK. In synchronism with (timing), a transition is made from the "H" level to the "L" level and held. In FIG. 2, signals G0 to G15 are pixels that match the values “0” to “15” of the signal DRMP (in this description, they are described as 4 bits, but the present invention is not limited to this). The timing waveforms of the comparator outputs S1 to SM corresponding to the data are shown. When the control signal CEN becomes “L” level, all outputs return to “H” level (with the transition timing when CEN in FIG. 2 falls, all of G0 to G15 are simultaneously returned from L to H level. ).

  The analog voltage generation circuit 12 generates an analog ramp wave ARMP whose voltage value linearly changes in synchronization with a digital signal DRMP (digital ramp signal) and a synchronization signal CCK. As shown in FIG. Output. The analog switch 17 outputs the analog ramp wave ARMP to the image display element when the output Sk (1 ≦ k ≦ M) of the comparator is “H” level, and shuts off when it is “L” level.

  The scanning line driving circuit 18 sequentially drives the outputs R1 to RN every horizontal scanning period to select one scanning line at a time. In the image display element, a transistor is disposed in each pixel, and the transistor connected to the selected scanning line is turned on to supply the analog ramp voltage ARMP from the analog switch to the corresponding pixel.

  Therefore, since the ARMP voltage value is held at each pixel when the pixel data coincides with the signal DRMP, if the change in the cycle of the signal DRMP corresponds to gamma correction, the pixel data and As shown in FIG. 3, the relationship between the corresponding supply voltages can correspond to the change in the period of the signal DRMP to the gamma correction, and the gamma correction characteristic can be obtained in the same manner as shown in FIG. That is, the horizontal axis shown in FIG. 3 is divided into n equal parts, and a curve showing the relationship between the supply voltage and the pixel data Dx shown in FIG. 3 and a line drawn in parallel to the vertical axis from each point divided into n parts. Intersection points are obtained, and the supply voltage obtained from these intersection points coincides with the gamma correction characteristics. And the relationship between these supply voltages and the transmittance | permeability T can be calculated | required similarly to FIG. If these are analyzed and output as a DRMP signal, the target analog ramp wave ARMP can be generated, and thus the lamp as the light source can be freely controlled.

  In the present embodiment, the voltage value of the analog ramp waveform changes linearly, but the present invention is not limited to this. In the present invention, the period of the signal DRMP is changed corresponding to the gamma correction, and the analog voltage generation circuit 12 synchronizes with the digital signal DRMP and the synchronization signal CCK, thereby freely generating the analog ramp wave ARMP. Can do.

[Embodiment 2] (Claims 2, 3, 6, 8, 9, 12)
FIG. 4 is a diagram schematically showing an example of digital signal generation means (for example, the digital signal generation circuit 13 of the first embodiment) used in the image display apparatus and the drive circuit thereof according to the present invention.
When the horizontal synchronizing signal HD as shown in FIG. 2 transits from “L” to “H”, the digital signal generation control circuit 130 sets the control signal CEN0 shown in FIG. The control signal CEN0 is output as a controlled signal CEN whose timing is optimized by the delay circuit 133 in order to optimize the timing with the analog ramp wave.

The gamma data memory 132 outputs gamma correction data GD based on the address RA.
The second counter 132 loads the gamma correction data GD and starts counting the system clock SCK when the control signal CEN becomes “H”. When the count value reaches the maximum, the output CCK is set to “H”. The actual count number from when the count is started until the count value becomes maximum differs depending on the loaded data GD. Therefore, if the data GD is controlled (set) to a desired value, the CCK cycle can be controlled accordingly (that is, by counting up to the set value).

When CCK becomes “H”, the control circuit 131 changes the address RA to an address different from the previous address and outputs the next gamma correction data GD. On the other hand, when CCK becomes “H”, the second counter 132 reloads the gamma correction data GD and repeats the counting operation.
The first counter 135 counts CCK and outputs the count value as a digital signal DRMP.
When the count value DRMP of the first counter 135 reaches a predetermined value, the control circuit 131 initializes the whole and sets the signal CEN0 to the “L” level.

[Embodiment 3] (Claims 2, 3, 9, 13)
FIG. 5 is a diagram schematically showing a configuration example of analog voltage generation means (for example, the analog voltage generation circuit 12 of the first embodiment) used in the image display apparatus of the present invention.
The level shift circuit 121 receives the digital pulse signal ASYN from the synchronization control circuit 19 in FIG. 1 and converts it into a pulse signal that swings or sweeps to ± Va. That is, the differential amplifier A1 in the level shift circuit 121 compares the signal ASYN with the threshold voltage Vth set by the resistors R1 and R2 and the signal ASYN. When the voltage value of the signal ASYN is lower than Vth, the output V1 of A1 is −Va, and when the voltage value of the signal ASYN is higher than Vth, the output V1 of A1 is + Va.

The integrating circuit 122 in the analog voltage generating means integrates the output signal V1 of A1 in the level shift circuit 121, generates a waveform whose voltage value changes linearly, and outputs this. When the output signal V1 of A1 is + Va, the charging current of the capacitor C1 flows through the resistor R3, and the output V2 of the differential amplifier A2 in the integrating circuit 122 is in the negative direction with a slope corresponding to the time constant C1 · R3. The voltage absolute value increases linearly. On the other hand, when V1 is -Va, the charging current of the capacitor C1 flows in the reverse direction through the resistor R4. Therefore, the output V2 of A2 in the integrating circuit 122 has a linear slope corresponding to the time constant C1 · R4, and the voltage value increases linearly from minus to zero. However, since V2 is clamped by diode D2, it does not exceed it when it reaches zero volts.
The output voltage V2 from the integrating circuit 122 can be adjusted to an optimum peak voltage value by controlling the value of the resistor R3, for example.

  The voltage V2 is input to the non-inverting amplifier and the inverting amplifier. The non-inverting amplifier adds the common voltage Vcom to the voltage V2 by the amplifier A3 and outputs the result. On the other hand, the differential amplifier A4 outputs a difference voltage between the voltages V2 and Vcom, that is, Vcom−V2 by the differential amplifier A4. As a result, the non-inverting amplifier outputs a negative ramp voltage with respect to the common voltage Vcom, and the inverting amplifier outputs a positive ramp voltage with respect to the common voltage Vcom.

  The analog switch alternately selects the output voltage from the non-inverting amplifier and the output voltage from the inverting amplifier based on the control signal S2 from the synchronous control circuit 19 of FIG. Output as voltage ARMP. As a result, when a liquid crystal display element is used as the image display element, the liquid crystal display element can be AC driven to ensure operation reliability.

[Embodiment 4] (Claim 13)
FIG. 6 schematically shows an example of the configuration of an LCOS in which a display unit including a liquid crystal layer and an electrode for driving the liquid crystal layer is formed on a silicon backplane as an example of an image display element used in the image display apparatus according to the present invention. FIG. That is, in LCOS (LIQUID CRYSTAL ON SILICON), a silicon substrate is used as one of upper and lower substrates enclosing liquid crystal. Since this silicon substrate is used, a microfabrication process similar to that of a normal semiconductor device can be used, and not only a pixel transistor but also a shift register, a latch circuit, a comparator, an analog switch, a scanning line driving circuit, etc. Reference) can also be configured on the same substrate, and a small and low-cost drive circuit can be realized.

[Embodiment 5] (Claims 14 to 16)
FIG. 7 is a diagram schematically showing a configuration example applied to a projection type image display device as an image display device according to the present invention.
In FIG. 7, the integrator optical system 102 is composed of, for example, a fly-eye lens array, and uniformizes light from the light source. The condenser lens 103 is for condensing and illuminating the illumination light from the light source 101 on the spatial light modulator. Here, the spatial light modulation element is a reflective liquid crystal panel, but is not limited to this, and other known light modulation elements can also be used.

  The drive circuit 1 includes the scanning line drive circuit and the signal line drive circuit shown in FIG. 1, the digital signal generation circuit shown in FIG. 4, and the analog voltage generation circuit shown in FIG. 5, and has a good gamma correction function. Have. The spatial light modulator 104 modulates illumination light incident on each pixel based on image data from the drive circuit 1. The illumination light that has been spatially modulated by the spatial light modulation element 104 is incident on the optical path deflecting element 106 as image light, and the incident image light is deflected so as to be shifted by a set amount in the pixel arrangement direction. Is done. The optical path deflection is controlled by the drive circuit 2. The polarization beam splitter 105 is for separating illumination light and image light.

Light emitted from the optical path deflecting element 106 is magnified by the projection lens 107 and projected onto the screen.
The optical path deflection amount is preferably 1 / n of the pixel pitch (n is an integer). For example, when performing image multiplication twice as much as the pixel arrangement direction, the pixel pitch is set to 1/2. When performing pixel multiplication of 4 times, the pixel pitch is set to 1/4. preferable. In any case, the image frame is composed of a plurality of sub-frames divided in time according to the number of deflection directions to be switched, and the optical path deflecting element 106 is operated for each sub-frame. By displaying the image information corresponding to the display position according to the action state on the image display element, it is possible to display an apparently high-definition image.

  In this example, a configuration using a reflective image display element as a spatial light modulation element, such as LCOS, has been described as an example. However, a configuration example using a transmissive image display element is also possible for the image display apparatus of the present invention. It is.

[Embodiment 6] (Claims 14, 15, and 17)
FIG. 8 is a diagram schematically showing a configuration example of another projection type image display device as the image display device according to the present invention.
Illumination light emitted from the light source is narrowed by a condenser lens and is incident on a rotating color separation disk disposed near the focal position.
As shown in FIG. 9, the rotating color separation disk is divided into a red transmissive region R, a green transmissive region G, and a blue transmissive region B, which are divided into three for each predetermined wavelength region. Separate colors. Each region is constituted by a filter made of a multilayer dielectric thin film or the like.

  As shown in FIG. 9, this rotating color separation disk is divided into R, G, and B, and is rotated by motor drive. As shown in FIG. 10, the display image data output is shown in FIG. In synchronization with the voltages V1 to V7 as shown, only the color corresponding to the wavelength range of the incident position of the illumination light is transmitted and incident on the spatial light modulator. For example, as shown in FIG. 10, if the image supply voltage is 0, the transmittance T is maximum, which is white, whereas if the image supply voltage is V7, the transmittance is minimum (0 in FIG. 10). : Origin) and black. Although the color gradation shown in FIG. 10 is 3 bits, this is merely an example, and the number of gradations is not limited. Again, the spatial light modulator is a reflective image display element.

  The driving circuit 1 includes the scanning line driving circuit and the signal line driving circuit shown in FIG. 1, the digital signal generation circuit shown in FIG. 4, and the analog voltage generation circuit shown in FIG. Data is output sequentially for each RGB color. The spatial light modulator 114 modulates illumination light incident on each pixel based on the display image data from the drive circuit 1. The illumination light that has been spatially modulated by the spatial light modulation element 114 is emitted as image light from the spatial light modulation element 114 and is enlarged and projected onto the screen surface by the projection lens 116. The polarization beam splitter 115 is for separating illumination light and image light. Similar to the above-described embodiment, the configuration using a reflective liquid crystal panel has been described as an example in the present embodiment, but a configuration example using a transmissive liquid crystal panel is also possible.

  The drive circuit of the present invention captures all devices (for example, image forming devices (including televisions), image input devices (videos, cameras, moving images, still images) of devices that require gamma correction such as liquid crystal display elements. Device (including mobile phones, portable terminals, and computers))), and a gamma correction value is obtained by reflecting the DRMP signal by inputting a gamma correction function by a known method. The present invention can also be applied as a method.

It is the figure which showed roughly an example of the structure of the image display apparatus which concerns on this invention, and its drive circuit. 2 is a timing chart showing an example of the operation of the image display device and its drive circuit shown in FIG. It is a figure which shows an example of the relationship between pixel data Dx and a supply voltage. It is the figure which showed roughly the example of a structure of the digital signal generation means (for example, digital signal generation circuit 13 of Embodiment 1) used for the image display apparatus of this invention. It is the figure which showed schematically the example of a structure of the analog voltage generation means (for example, analog voltage generation circuit 12 of Embodiment 1) used for the image display apparatus of this invention. The figure which showed typically the structural example of LCOS which formed the display part containing the liquid crystal layer and the electrode which drives it on a silicon | silicone backplane as an example of the image display element used for the image display apparatus which concerns on this invention. It is. It is the figure which showed roughly the structural example applied to the projection type image display apparatus as an image display apparatus which concerns on this invention. It is the figure which showed roughly the other structural example applied to the projection type image display apparatus as an image display apparatus which concerns on this invention. It is a figure which shows an example of the rotation color separation disk divided | segmented into the red permeation | transmission area | region R divided into 3 for every predetermined wavelength range, the green permeation | transmission area | region G, and the blue permeation | transmission area | region B. It is a figure which shows an example of the relationship between the pixel supply voltage of an image display element (liquid crystal display element), and the light transmittance. It is a figure which shows the example of 1 structure of the means which performed the correction | amendment according to the VT characteristic of the liquid crystal with respect to the conventional analog ramp wave (it can be used also in this invention). It is a figure which shows an example of the relationship between the pixel data of an image display element (liquid crystal display element), and the supply voltage V (or light transmittance T).

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Image data generation circuit 12 Analog voltage generation circuit 13 Digital signal generation circuit 14 Comparator 15 Shift register 16 Latch circuit 17 Analog switch

Claims (20)

  Image data generating means for generating n-bit pixel data corresponding to each pixel, analog voltage generating means for generating an analog ramp wave whose voltage value periodically varies within a predetermined range, and voltage value of the analog ramp wave The analog ramp wave according to the timing at which the pixel data and the digital signal match each other, and a digital signal generating means for generating an n-bit digital signal corresponding to the above and a comparator for comparing the pixel data with the digital signal. In accordance with the voltage / transmittance characteristics of each pixel in synchronization with the switching timing of the digital signal value of the driving circuit of the image display apparatus that supplies the corresponding voltage value to the corresponding pixel and displays a desired image. A drive circuit for an image display device, comprising gamma correction means for performing gamma correction of the pixel data.   The gamma correction unit includes a pulse signal generation unit that generates a pulse signal in which the generation timing of the rising or falling transition or both changes according to the voltage / transmittance characteristics of each pixel, and the rising or rising of the pulse signal. The drive circuit for an image display device according to claim 1, further comprising an n-bit first counter that counts downstream transitions or both, and using an output of the counter as the digital signal.   The pulse signal generation means loads a gamma correction data storage means for storing gamma correction data, counts a clock signal having a predetermined frequency by loading the gamma correction data, and outputs a count number corresponding to the loaded gamma correction data. 3. The drive circuit for an image display device according to claim 2, further comprising: a second counter that outputs a signal that causes a transition later, and using the output signal of the second counter as the pulse signal.   The drive circuit for an image display device according to claim 1, wherein the analog ramp wave includes a time region in which a voltage value linearly changes with time for each period.   5. The drive circuit for an image display device according to claim 1, further comprising a voltage adjustment unit configured to vary a predetermined voltage range of the analog ramp wave.   6. The drive circuit for an image display device according to claim 1, further comprising timing adjusting means for adjusting a timing at which the value of the digital signal is switched.   An image display element having a plurality of pixels for displaying an image according to a supplied voltage value, an image data generating means for generating n-bit pixel data corresponding to each of the plurality of pixels, and a voltage within a predetermined range Analog voltage generating means for generating an analog ramp wave whose value periodically changes, digital signal generating means for generating an n-bit digital signal corresponding to the voltage value of the analog ramp wave, the pixel data and the digital signal A digital comparator of the image display device for supplying a voltage value of the analog ramp wave corresponding to a timing at which the pixel data and the digital signal coincide with each other to display the desired image. Gamma correction of the pixel data according to the voltage / transmittance characteristics of each pixel in synchronism with the timing of signal value switching The image display apparatus characterized by comprising a gamma correction means for performing.   The gamma correction unit includes a pulse signal generation unit that generates a pulse signal in which the generation timing of the rising or falling transition or both changes according to the voltage / transmittance characteristics of each pixel, and the rising or rising of the pulse signal. The image display apparatus according to claim 7, further comprising: an n-bit first counter that counts a downstream transition or both, and an output of the counter is used as the digital signal.   The pulse signal generation means loads a gamma correction data storage means for storing gamma correction data, counts a clock signal having a predetermined frequency by loading the gamma correction data, and outputs a count number corresponding to the loaded gamma correction data. The image display apparatus according to claim 7, further comprising a second counter that outputs a signal that causes a transition later, and using the output signal of the second counter as the pulse signal.   The image display apparatus according to claim 7, wherein the analog ramp wave includes a time region in which a voltage value linearly changes with time in one cycle.   The image display device according to any one of claims 7 to 10, further comprising a voltage adjusting unit that makes a predetermined voltage range of the analog ramp wave variable.   The image display device according to claim 7, further comprising a timing adjustment unit that adjusts a timing at which the value of the digital signal is switched.   The image display device is an image display element in which LCOS (Liquid Crystal On Silicon) in which a display unit including a liquid crystal layer and an electrode for driving the liquid crystal layer is formed on a silicon backplane is formed in an element shape. Item 13. The image display device according to any one of Items 7 to 12.   The image display device according to any one of claims 1 to 13, an illumination device that is a light source for illuminating the image display element of the image display device, and light emitted from the image display device is enlarged / reduced and projected. An optical device for projecting on a surface, and forming an image on the projection surface by enlarging and / or reducing and projecting light emitted from the image display element that has been spatially light-modulated based on the pixel data. Projection image display device.   The image data generation means includes subframe image data generation means for dividing a display image for one frame into a plurality of subframe images and sequentially time-dividing each subframe for output, and time-division projection for each subframe. The projected image display device according to claim 14, wherein the image pattern is synthesized on the projection surface to display the image for one frame.   The sub-frame image data generation means outputs pixel data corresponding to a pixel arrangement selected from the display image for one frame as one sub-frame, and the optical device outputs an optical path of light emitted from the image display element. An optical path deflecting means for deflecting, and controlling the deflection state of the optical path of the emitted light spatially modulated by the image display element in correspondence with the sub-frame to display the image by shifting the display position on the projection plane; The projected image display device according to claim 14, wherein an image simulated to have a number of pixels substantially larger than the number of pixels of the image display element is displayed.   The sub-frame image data generation means outputs pixel data by corresponding the display image for one frame as one sub-frame for each color, and the illumination device separates light from the light source into a predetermined color. A color separation element that sequentially enters the image display element, and displays a color image obtained by synthesizing, on the projection surface, outgoing light that is spatially modulated for each subframe corresponding to the color of the incident light. The projection image display apparatus according to any one of claims 14 to 16, wherein:   Using an image display device, pixel data corresponding to each pixel is synchronized with a digital signal corresponding to an analog ramp wave for changing the light transmittance of a display element in the image display device. A method for controlling the light transmittance of a display element, comprising a portion in which the voltage is linearly changed for each period period which is one horizontal scanning period of the analog ramp wave.   A method for controlling light transmittance of a display element, wherein an analog ramp wave is formed in synchronization with a clock signal obtained from a digital ramp signal in the order of output of pixel data.   Synchronizing pixel data corresponding to each pixel by the image display device and a digital signal corresponding to an analog ramp wave for changing the light transmittance of the display element in the image display device, A program for controlling the light transmittance of a display element, including a portion in which a voltage is linearly changed for each cycle period which is one horizontal scanning period of an analog ramp wave.

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