Patent Application
20080024652
Exemplary embodiments of the invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
At first, an electro-optical device, an image processing circuit, an image processing method, and an electronic device including the electro-optical device according to embodiments of the present invention will be described. A three panel-type projector (projection-type projector) using a liquid crystal display panel that is a type of electro-optical device as a light valve is exemplified in the embodiments. The projector is an example of the electronic device according to an embodiment of the invention. The projector can project a composed image of projection images that project through three light valves corresponding to R (red light), G (green light), and B (blue light) on a projection surface such as a screen on an enlarged scale.
At first, an electrical configuration of a projector 1100 according to an embodiment of the invention will be described with reference to
The liquid crystal display panels 100R, 100G, and 100B respectively correspond to primary color light of R (red), G (green), and B (blue) and display an image using the colors. Each of the liquid crystal display panels 100R, 100G, and 100B is formed by sandwiching liquid crystals between a component substrate and an opposite substrate, and a data line driving circuit 101 and a scanning line driving circuit 102 are provided on peripheral edges of a display area 103 of the component substrate.
A plurality of data lines and a plurality of scanning lines are formed so as to intersect each other in the display area 103. TFTs serving as switching elements are provided in correspondence with the intersections of the data lines and the scanning lines. A gate electrode, a source electrode, and a drain electrode of each TFT are electrically connected respectively to a scanning line, a data line, and a pixel electrode. One pixel is formed by a TFT, a pixel electrode, and an opposite electrode provided on the opposite substrate. The position of a pixel in the display area 103 is given by a set of coordinates.
The data line driving circuit 110 and the scanning line driving circuit 102 drive the pixels by supplying various signals respectively to the plurality of data lines and the plurality of scanning lines which are formed in the display area 103. In the embodiment, the number of dots of the display area 103 is assumed to correspond to XGA (1024 horizontal dots×768 vertical dots) for the convenience of description.
The timing circuit 200 supplies various timing signals to the data line driving circuit 101, the scanning line driving circuit 102, and the image signal processing circuit 300 when the projector 100 is operated. The image signal processing circuit 300 includes a gamma correction circuit 301, a color non-uniformity correction circuit 302, S/P conversion circuits 303R, 303G, and 303B, and inverting amplifier circuits 304R, 304G, and 304B.
The gamma correction circuit 301 performs gamma correction respectively for input image data DR, DG, and DB, which are digital signals, in accordance with display characteristics of the liquid crystal panels 100R, 100G, and 100B and outputs resultant image data DR′, DG′, and DB′.
The color non-uniformity correction circuit 302 includes a first color non-uniformity correction circuit 302-1 which is an example of a first input image correction circuit and a second color non-uniformity correction circuit 302-2 which is an example of a second input image correction circuit.
The color non-uniformity correction circuit 302 performs a color non-uniformity correction process to be described later for the image data DR′, DG′, and DB′ which are examples of corrected input image data and performs a D/A conversion process on the corrected data for outputting resultant signals as image signals VIDR, VIDG, and VIDB. The configurations and operations of the first color non-uniformity correction circuit 302-1 and the second color non-uniformity correction circuit 302-2 will be described later in detail.
The S/P conversion circuit 303R corresponding to R distributes the image signal VIDR into six series and expands (serial-parallel conversion) the image signal by six times in the time axis for outputting. The reason for the conversion into image signals of six series is to acquire the sampling time and charge/discharge time of a data signal of the liquid crystal display panel sufficiently by lengthening the application time of the image signal supplied to a TFT in a sampling circuit (built in the data line driving circuit 101) of the liquid display panel.
The inverting amplifier circuit 304R corresponding to R inverts the polarity of the image signals and amplifies the inverted image signals to supply the resultant signals to the liquid crystal display panel 100R as image signals VIDr1 to VIDr6.
In addition, the image signal VIDG corresponding to G output by the color non-uniformity correction circuit 302 is similarly converted into six series by the S/P conversion circuit 303G and then amplified with the polarity inverted by the inverting amplifier circuit 304G for being supplied as image signals VIDg1 to VIDg6 to the display panel 100G. Similarly, the image signal VIDB corresponding to B is converted into six series by the S/P conversion circuit 303B and then amplified with the polarity inverted by the inverting amplifier circuit 304B so as to be supplied as image signals VIDb1 to VIDb6 to the liquid crystal display panel 100B.
The polarity inversion in the inverting amplifier circuits 304R, 304G, and 304B involves inverting the voltage level of the image signal alternatingly with respect to the amplitude center voltage of the image signal as a reference. The period of polarity inversion may be arbitrarily set as polarity inversion in units of scanning lines, polarity inversion in units of data signal lines, or polarity inversion in units of one frame on the basis of the application mode of the data signal.
Next, the detailed configuration of the projector 1100 will be described with reference to
The image signals VIDr1 to VIDr6, VIDg1 to VIDg6, and VIDb1 to VIDb6 of R, G, and B that are processed by the image signal processing circuit 300 (omitted in
As for the zoom function, digital zoom performed by signal processing along with optical zoom performed by a zoom operation of the projection lens may be used.
The configurations of the first and second color non-uniformity correction circuits 302-1 and 302-2 which are included in the color non-uniformity correction circuit 302 will be described with reference to
Hereinafter, a process performed for image data corresponding to R (red) and circuit units performing the process will be mainly described, however, the same process is performed for the image data corresponding to G (green) and B (blue) by using the same configuration as that for the image data corresponding to R.
In
The zoom amount detecting circuit 310 detects the zoom amount of the projection lens 1114, to be more specific, the shift amount of the projection lens 1114 shifted in correspondence with the wide (enlargement) side and tele (reduction) side.
The memory device 311 includes a plurality of lookup tables including the first reference correction data set in correspondence with a plurality of specific zoom amounts among the zoom amounts that the projection lens 1114 can have. In this embodiment, as detailed examples of the plurality of lookup tables, a LUT 312W including the first reference correction data piece set in the wide side and a LUT 312T including the first reference correction data piece set in the tele side are included. The first reference data included in LUTs 312W and 312T are respectively correction values for input image data DR′ that are used for correcting the input image data DR′ such that the color non-uniformity does not occur in a projection image when the projection image is projected on a screen with the projection lens 1114 shifted to wide side and tele side in advance.
While the first reference correction data are set for the zoom amounts of the projection lens 1114, that is, specific values of the absolute values of shifted amount in cases where the projection lens 1114 is shifted respectively to the wide side and the tele side in this embodiment, the first reference correction data may be set for a plurality of specific zoom amount among the zoom amounts of the projection lens 1114 that are shifted amounts of the projection lens 1114 respectively to the wide side and the tele side from a reference zoom amount among the zoom amounts of the projection lens 1114 for which the color non-uniformity does not occur in the projection image without correction of the input image data DR′.
The calculation unit 313 acquires information on the zoom amount of the projection lens 1114 from the zoom amount detecting circuit 310. The calculation unit 313 reads out the data stored in LUTs 312W and 312T and calculates the first correction data on the basis of the zoom amount that has been acquired from the zoom amount detecting circuit 310 corresponding to the zoom amount.
To be more specific, as shown in
Again in
In this embodiment, the memory device 311 nay store the first reference correction data for each luminance level of the input image data DR′ or each reference coordinate, and the calculation unit 313 may interpolate the plurality of first reference correction data for each of different specific levels included in the plurality of specific levels or for each set of different reference coordinates among the plurality of sets of reference coordinates. In this case, before the second color non-uniformity correction circuit 303-2 corrects the input image data DR″, the luminance non-uniformity of the image displayed in the display area 103 can be reduced. The precision of the first correction data that is generated by interpolating the first reference correction data for each of the different specific levels or each set of the different reference coordinates on the basis of the zoom amount of the projection lens 1114 is lower than that of the second correction data that is generated by the second color non-uniformity correction circuit 302-2. To be more specific, since the first correction data may be generated by the first color non-uniformity correction circuit 302-1 such that the color non-uniformity occurring due to the zoom amount of the projection lens 1114 is not detected, the interpolation is performed on the basis of reference values, the number of which is less than that for the second reference data that is generated on the basis of both the plurality of specific levels and the plurality of reference coordinate levels, and accordingly, the precision of the correction for the input image data DR′ may be low.
Next, the configuration of the second color non-uniformity circuit 302-2 will be described with reference to
When the projector 1100 is operated, the X counter 10 counts a dot clock signal DCLK synchronized with a dot period and outputs X coordinate data Dx representing the X coordinate of the input image data. The Y counter 11 counts a horizontal clock signal HCLK synchronized with horizontal scanning and outputs Y coordinate data Dy representing the Y coordinate of the input image data. Accordingly, the set of coordinates of a dot (pixel) corresponding to the input image data can be detected by referring to the X coordinate data Dx and the Y coordinate data Dy.
The ROM 12 is a non-volatile memory. The ROM 12 outputs reference correction data Dref that is an example of the second reference correction data when power is supplied to the projector 1100. The reference correction data Dref corresponds to a plurality of sets of predetermined reference coordinates and specific levels of the colors of R, G, and B and becomes reference data for correcting the color non-uniformity using the second color non-uniformity correction circuit 302-2.
Here, the sets of reference coordinates in the embodiment will be described with reference to
Next, the specific levels for each color of R, G, and B will be described with reference to
As shown in
Here, the reasons the above-described three voltage levels are selected are as follows. First, since the change in the transmittance is small in the region having a voltage level smaller than the voltage level V1 or the region having a voltage level larger than the voltage level V3 although the levels (gradation or luminance) of the image data are markedly different, it can be generally assumed that using reference correction data Dref corresponding to the voltage level V1 or the voltage level V3 is sufficient. Second, when the reference correction data Dref corresponding to the voltage levels V0 and V4 instead of the voltage levels V1 and V3 is stored and correction data corresponding to each level in the range of the voltage levels V0 to V4 is calculated by interpolation, the display characteristic W changes rapidly at the voltage levels V1 and V3, and accordingly correction data cannot be calculated precisely over the whole region. Third, by using the voltage level V2 at which the transmittance is about 50%, the precision of the interpolation process can be improved.
When the above reasons are considered, since a liquid crystal display panel has a display characteristic depending on the composition of liquid crystals serving as electro-optical materials generally, the second color non-uniformity correction circuit 302-2 cannot perform precise correction, although all the levels that the image data can have are corrected using correction data corresponding to one level of the image data. To the contrary, it is ideal to store correction data in correspondence with all the levels of the image data, but in such a case, the required storage capacity in the ROM 12 increases, Thus, the second color non-uniformity correction circuit 302-2 stores reference correction data Dref in correspondence with three different levels, and correction data corresponding to levels other than the above-described three different levels is acquired by performing an interpolation process for the stored reference correction data Dref.
Next, the contents stored in the ROM 12 will be described with reference to
Next, the setting of the reference correction data will be described with reference to
At first, a signal generator which is not shown in the figure is connected to the system 1000 and supplies image data DR′ of R corresponding to the white reference level (image data DG′ and DB′ is fixed in correspondence with a voltage level V4 of the minimum transmittance). Accordingly, a projection image of one red color is displayed on the screen S. Next, the projection image is photographed by the CCD camera 500 and supplied to the personal computer 600 as the image signal Vs. Thereafter, the personal computer 600 divides the screen of one frame into six vertical blocks X eight horizontal blocks as shown in
Thereafter, the personal computer 600 compares the luminance level of the set of reference coordinates with a predetermined luminance level and calculates reference correction data Dref on the basis of the comparison result. In addition, the personal computer 600 performs the calculation operation similarly for the 63 sets of reference coordinates, the center reference level (voltage level V2), and the black reference level (voltage level V3) and calculates reference correction data Drefr in correspondence with R.
Subsequently, the image data DR′ and DB′ are fixed in correspondence with the voltage level V4 of the minimum transmittance, the image data DG′ of G is sequentially converted to correspond to the white reference level, the center reference level, and the black reference level, and the reference correction data Drefg corresponding to G are calculated by the personal computer 600. Similarly, the image data DR′ and DG′ are fixed so as to correspond to the voltage level V4 of the minimum transmittance, the image data DB′ of B is sequentially converted to correspond to the white reference level, the center reference level, and the black reference level, and the reference correction data Drefb corresponding to B are calculated by the personal computer 600. The calculated reference correction data Drefr, Drefg, and Drefb are stored in the ROM 12 of the projector 1100. Accordingly, the reference correction data is stored in the ROM 12.
Again in
Next, in
The correction table 14R stores the correction data DHr calculated by the interpolation processing unit 13 in a region having the set of reference coordinates as a row address and the level as a column address which is a coordinate axis and outputs correction data DHr1 to DHr4 of four points from a storage region designated by a read address.
Here, the contents stored in the correction table 14R will be described with reference to
In
Second, the address generating unit 17R generates a row address corresponding to a level of the image data DR″. For example, when the level of the image data DR″ is “m+1”, the row address indicating the second row is generated. However, when the level of the image data DR″ is smaller than “m”, a row address indicating the first row is generated, and when the level of the image data DR″ is larger than “n”, a row address corresponding to “n” is generated.
Third, the address generating unit 17R generates four read-out addresses by combining four row addresses and one column address. Four correction data pieces DHr1 to DHr4 from the correction data DHr stored in the correction table 14R are selected by the address generating unit 14R. For example, when the image data DR′ is “m+1” and the coordinates given by the X coordinate Dx and the Y coordinate Dy is (64, 64), “DHr1, 1(m+1)”, “DHr128, 1(m+1)”, “DHr1, 128(m+1)”, and “DHr128, 128(m+1)” are read out from the correction table 14R as the correction data pieces DHr1 to DHr4 in
Next, the calculation unit 15R acquires correction data Dh corresponding to the set of coordinates (set of coordinates corresponding to the image data DR″) specified by the X coordinate Dx and the Y coordinate Dy by performing an interpolation process using the correction data pieces DHr1 to DHr4 of the four read-out points, To be more specific, the calculation unit 15R acquires the correction data Dh by performing linear interpolation for the correction data pieces DHr1 to DHr4 of four points along each distance from the coordinates given by the X coordinate Dx and the Y coordinate Dy to the coordinates corresponding to the correction data pieces DHr1 to DHr4.
The adding unit 16R generates image data to which the correction process has been completed by adding the image data DR″ and the correction data Dh. The image data to which the correction process has been completed is output as an analog image signal VIDR through the D/A converter 18R. In this embodiment, a case where the image data DR″ of R (red) is corrected is described in detail, but the same color non-uniformity correction process is performed for the image data DR″ of G (green) and the image data DR″ of B (blue) to be output as analog signals VIDG and VIDB.
Next, an image processing method according to an embodiment of the invention will be described with reference to
At first, the process performed in the first color non-uniformity correction circuit 302-1 will be described. When the power is supplied to the projector 1100 (step S100), the zoom amount detecting circuit 310 detects the zoom amount of the projection lens 1114 in a status that the projector 1100 can project a projection image on the screen (S111). The calculation unit 313 reads out the first reference correction data from the memory device 311 and generates correction data on the basis of the zoom amount read by the zoom amount detecting circuit 310(S112). An adder 314 corrects the input image data DR′ by adding the generated correction data to the input image data DR′ and outputs the input image data DR″ for which the color non-uniformity due to the zoom amount can be reduced to the second color non-uniformity correction circuit 302-2 in the latter stage.
Next, the process performed in the second color non-uniformity correction circuit 302-2 will be described. When the power is supplied to the projector 1100 (step S100), the reference correction data Dref (Drefr, Drefg, and Drefb) corresponding to each set of reference coordinates is read from the ROM 12 in a status that the projector 1100 can project a projection image on the screen (step S121). Next, the interpolation processing unit 13 generates the correction data pieces DHr, DHg, and DHb by performing an interpolation process in a gradation (level) direction on the basis of the reference correction data Dref (step S122). In other words, since each of the reference correction data pieces Drefr, Drefg, and Drefr correspond only to three voltage levels V1, V2, and V3 in the sets of reference coordinates including 63 points, the correction data pieces DHr, DHg, and DHb corresponding to each level from the voltage level V1 to the voltage level V3 are generated respectively by interpolation processes.
Next, when the correction data pieces DHr, DHg, and DHb are stored respectively in correction tables of the correction units UR2, UG2, and UB2, a dot clock signal DCLK and a horizontal clock signal HCLK are respectively supplied to the X counter 10 and the Y counter 11 (step S123), and the image data DR″, DG″, and DB″ is supplied in synchronization with the clock signals. Here, it can be determined that to which dot (pixel) in the display area 103 the image data DR″, DG″, and DB″ corresponds in a specific timing by the X coordinate data Dx output from the X counter 10 and the Y coordinate data Dy output from the Y counter 11.
Thereafter, four correction data pieces DHr1 to DHr4 that become the base of the interpolation process for the coordinates are read out from the correction table 14R on the basis of the X coordinate data Dx, the Y coordinate data Dy, and the level of the image data DR″ (step S124). This operation also applies for other colors. Thereafter, the correction data Dh is generated (step S126) by interpolating the correction data pieces DHr1 to DHr4 on the basis of the X coordinate data Dx and the Y coordinate data Dy using the calculation unit 15R (step S125). The correction data Dh is added to the image data DR″ by the adding unit 16R (step S127), and the resultant data is converted by the D/A converter 15R into analog data to be output as the image signal VIDR of R (red). The same process is performed for G (green) and B (blue) and then, the resultant data is output as image signals VIDG and VIDB.
By using the above-described image processing method according to an embodiment of the invention, the input image data can be corrected at a high speed, whereby the color non-uniformity occurring due to the zoom amount of the projection lens 1114 can be reduced. In addition, the correction data Dh is generated by generating the Correction data DH corresponding to each level of the image data for each set of reference coordinates from the reference correction data Dref corresponding to each set of coordinates and three voltage levels V1, V2, and V3 and performing an interpolation process for the correction data pieces DHr1 to DHr4 of four points on the basis of the X coordinate data Dx and the Y coordinate data Dy. Accordingly, since a precise correction is performed on the basis of each level of the image data DR″, DG″, and DB″, the color non-uniformity or the luminance non-uniformity can be markedly reduced over all the gradations.
Since the correction data Dh is generated for each of the image data pieces DR″, DG″, DB″, it is possible to maintain white balance by supplementing with G and B in a case where the correction amount of R is insufficient. For example, when the number of bits of the image data DR″, DG″ and DB″ is ten and the number of bits of the correction data Dh is limited to four, there may be a case where the color non-uniformity cannot be completely corrected by a correction process for each color, but the color non-uniformity can be corrected by correcting using balances with other colors.
In the embodiment, since the interpolation process corresponding to the coordinates is performed after the interpolation process corresponding to the level of the gradation or the like, that is, the interpolation processes of two stages are performed, the required memory capacity of the ROM 12 and the correction table 14R can be reduced markedly. In addition, since the X counter 10, the Y counter 11, the ROM 12, and the interpolation processing unit 13 also serves as correction units UR2, UG2, and UB2, the configuration can be simple to that amount, whereby it becomes possible to reduce the costs.
Next, an electro-optical device, an image processing circuit, and an image processing method according to other embodiments of the invention will be described with reference to
The electrical configuration of a projector 1400 according to another embodiment of the invention will be described with reference to
The image signal processing circuit 400 includes a gamma correction circuit 301 and a color non-uniformity correction circuit 402 and an S/P conversion circuit 303 and an inverting amplifier circuit 304 which correspond to each color of red (R), green (G) and blue (B).
The color non-uniformity correction circuit 402 performs a color non-uniformity correction process, to be described later, for the input image data DR′, DG′, and DB′ and performs a D/A conversion process on the corrected input image data for outputting resultant signals as image signals VIDR, VIDC, and VIDB. The gamma correction circuit 301, the S/P conversion circuit 303, and the inverting amplifier circuit 304 perform the same processes as in the first embodiment. Hereinafter, the case where the input image data of red (R) is corrected will be described in detail.
The configuration of a color non-uniformity correction circuit 402 included in an image processing circuit according to another embodiment of the invention will be described with reference to
In
The memory 12 is an example of the reference correction data storage circuit and stores reference correction data for correcting input image data DR′, to be described later, for each of a plurality of sets of reference coordinates. The reference coordinates means the same as described in the first embodiment. The interpolation processing unit 13 is an example of the first correction data generating circuit. The interpolation processing unit generates first correction data corresponding to each level of the input image data DR′ for each set of coordinates by performing an interpolation process on the reference correction data for the gradation level of the input image data. The correction table 14R is an example of the first correction data storage circuit and stores the first correction data generated by the interpolation processing unit 13 in correspondence with the reference coordinates and the level. The calculation unit 15R serves as both the selection circuit and the correction data generating circuit. The calculation unit selects a first correction data piece from the first correction data stored in the correction table 14R that corresponds to a plurality of sets of reference coordinates in the display area 103 positioned in proximity of the coordinates given by the address information and the level of the input image data DR′. To be more specific, the calculation unit 15R selects the first correction data pieces DHr1, DHr2, DHr3, and DHr4 from the correction table 14R on the basis of the address information of a pixel corresponding to the input image data DR′ determined on the basis of the address information supplied from the address generating circuit 17R, that is, the clock signals DCLK and HCLK.
The correction coefficient generating unit 19R is an example of the second correction circuit and generates correction data Dh′ by multiplying the correction data Dh output from the calculation unit 15R by a correction coefficient. The adding unit 16R adds the correction data Dh′ to the input image data DR′. The input image data DR′ corrected on the basis of the correction data Dh′ is converted into an analog signal by the D/A converter 18R to be output as an image signal VIDR.
Next, the configuration of the correction coefficient generating unit 19R will be described with reference to
The LUT 21R stores a correction coefficient K for reducing the color non-uniformity occurring due to the size of a projection image that is projected on the screen corresponding to the input image data DR′. The zoom amount detecting circuit 22R detects the zoom amount of the projection lens 1114. The calculation unit 23R detects the zoom amount of the projection lens 1114 from the zoom amount detecting circuit 22R, that is, the size of the projection image and reads out a correction coefficient corresponding to the size from the LUT 21R and multiplies the correction data Dh by the correction coefficient. Accordingly, the correction data Dh′ that can be used for reducing the color non-uniformity occurring due to the size of a projection image is generated. The adding unit 16R corrects the input image data DR′ by adding the correction data Dh′ to the input image data DR′. For the input image data corresponding to green (G) and blue (B), the same process is performed, thereby the color non-uniformity of the projection image is reduced. In addition, since the correction data that can be used for reducing the color non-uniformity is generated by multiplying the correction data Dh by the correction coefficient K, the correction data can be corrected at a high speed without individually storing the correction data corresponding to the size of the projection image in the memory 12 in advance. By using the correction data, the input image data can be corrected at a high speed.
Next, an image processing method performed in the projector 1400 will be described with reference to
At first, when the power is supplied to the projector 1100 (step S100), the zoom amount detecting circuit 22R detects the zoom amount of the projection lens 1114 in a status that the projector 1400 can project a projection image on the screen (step S131). The calculation unit 313 detects the zoom amount from the zoom amount detecting circuit 22R and generates a correction coefficient K corresponding to the read zoom amount on the basis of the data read-out from the memory 21R (step S132). The operations of the steps S121 to S126 are performed, as in the first embodiment, simultaneously with the operations of the steps S131 and S132 or before/after the operations of the steps S131 and S132, whereby the correction data Dh is corrected on the basis of the correction coefficient K (step S128). Thereafter, the adding unit 16R generates input image data to which the correction process has been completed by adding the corrected correction data Dh′ to the input image data DR′ (step S127). The input image data corrected as described above is converted from digital data to analog data by the D/A converter 18R to be output.
By using the above-described method, the correction data Dh is corrected on the basis of the correction coefficient K only, and accordingly, the correction data can be corrected at a high speed, whereby the color non-uniformity occurring due to the size of a projection image can be effectively reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-201665 | Jul 2006 | JP | national |
