JP2015064467A - Image processing circuit, electro-optic device, image processing method, and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent disclination and prevent the contrast from being reduced in a part having a gray level difference.SOLUTION: When a dark pixel to be applied with a voltage less than a first threshold and a bright pixel to be applied with a voltage higher than a second threshold are adjacent to each other, the voltage to be applied to the dark pixel is made higher than the previous one, while the voltage to be applied to the bright pixel is made lower than the previous one. The voltage to be applied to a pixel which is located second on the side of the dark pixel from a boundary between the dark pixel and the bright pixel is made lower than the previous one, while the voltage to be applied to a pixel which is located second on the side of the bright pixel from the boundary between the dark pixel and the bright pixel is made higher than the previous one.

Description

  The present invention relates to a technique for suppressing the occurrence of alignment defects in liquid crystals.

  In a liquid crystal panel, a horizontal electric field is generated between adjacent pixels due to a potential difference between adjacent pixels, and liquid crystal alignment defects (disclination) due to the horizontal electric field may occur. Since the occurrence of disclination causes a reduction in display quality of the liquid crystal panel, an invention for suppressing the occurrence of disclination has been made as disclosed in, for example, Patent Document 1.

JP 2009-237366 A

  In the invention disclosed in Patent Document 1, the driving voltage of a pixel is corrected so that the difference in driving voltage between two adjacent pixels becomes small. As a result, the potential difference between adjacent pixels is reduced to suppress the generation of a transverse electric field and to suppress the occurrence of disclination. However, when the potential difference between adjacent pixels is reduced, the gradation difference between the two pixels is reduced. Compared with the case where correction is not performed, the contrast of the portion having the gradation difference is reduced. Become.

  The present invention has been made in view of the above-described circumstances, and one of its purposes is to suppress the occurrence of disclination and to prevent a decrease in contrast in a portion having a gradation difference.

In order to achieve the above object, an image processing circuit according to the present invention receives video data designating an applied voltage for each pixel and defines an applied voltage of the pixel by correction data obtained by correcting the video data. A first pixel whose applied voltage specified by the video data is lower than a first threshold, and an applied voltage specified by the video data exceeds a second threshold higher than the first threshold. A boundary detection unit that detects a boundary with the second pixel; and the video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary. The video image so that a voltage difference between the applied voltage of the third pixel adjacent to the side opposite to the boundary when viewed from the second pixel and the applied voltage of the fourth pixel adjacent to the side opposite to the boundary viewed from the second pixel is increased. Correct data It has a Tadashibu, the.
According to the present invention, it is possible to suppress the occurrence of disclination and prevent a decrease in contrast in a portion having a gradation difference.

In the present invention, the correction unit may correct the applied voltage of the third pixel and correct the applied voltage of the fourth pixel.
According to this configuration, since the gradation difference between the pixels sandwiching the pixels adjacent to the boundary increases, it is possible to prevent a decrease in contrast in a portion where there is a gradation difference.

In the present invention, the correction unit may be configured such that the applied voltage of the fifth pixel adjacent to the side opposite to the boundary as viewed from the third pixel and the side opposite to the boundary as viewed from the fourth pixel. The video data may be corrected so that a voltage difference from the applied voltage of the adjacent sixth pixel becomes large.
According to this configuration, since the gradation difference between the third pixels counted from the boundary increases, it is possible to prevent a decrease in contrast in a portion where there is a gradation difference.

The image processing circuit according to the present invention is an image processing circuit that receives video data designating an applied voltage for each pixel and defines the applied voltage of the pixel by correction data obtained by correcting the video data. A boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. The image data is corrected so as to reduce a lateral electric field generated between the boundary detection unit to detect, the first pixel and the second pixel adjacent to the boundary, and is opposite to the boundary when viewed from the first pixel. The video data is corrected so that a voltage difference between the applied voltage of the third pixel adjacent to the second pixel and the applied voltage of the fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is reduced; Before seeing from 3 pixels The video data so that a voltage difference between the applied voltage of the fifth pixel adjacent to the side opposite to the boundary and the applied voltage of the sixth pixel adjacent to the side opposite to the boundary when viewed from the fourth pixel is increased. A correction unit that corrects.
According to this configuration, it is possible to suppress the occurrence of disclination and to prevent a decrease in contrast in a portion having a gradation difference.

In the present invention, the correction unit may be configured to vary the amount of correction for the third pixel to the sixth pixel according to the applied voltage represented by the video data.
According to this configuration, it is possible to further prevent a decrease in contrast in a portion where there is a difference in gradation as compared with a case where the correction amount is constant.

In the electro-optical device according to the invention, a plurality of pixels and video data designating an applied voltage for each pixel are input, and an applied voltage of the pixel is defined by correction data obtained by correcting the video data. An image processing circuit configured to output a first pixel whose applied voltage specified by the video data is lower than a first threshold value, and an applied voltage specified by the video data from the first threshold value. A boundary detection unit that detects a boundary with a second pixel that is higher than a second threshold value, and corrects the video data so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary. And the voltage difference between the applied voltage of the third pixel adjacent to the opposite side of the boundary when viewed from the first pixel and the applied voltage of the fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel. So that the Having a correction unit for correcting the data.
According to this configuration, it is possible to suppress the occurrence of disclination and to prevent a decrease in contrast in a portion having a gradation difference.

In another electro-optical device according to the invention, a plurality of pixels and video data designating an applied voltage for each pixel are input, and the applied voltage of the pixels is set by correction data obtained by correcting the video data. Each of the image processing circuits defining a first pixel whose applied voltage specified by the video data is below a first threshold, and the applied voltage specified by the video data is the first image processing circuit. A boundary detection unit that detects a boundary with a second pixel that exceeds a second threshold value that is higher than a threshold value, and the video data so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary. And the applied voltage of the third pixel adjacent to the side opposite to the boundary when viewed from the first pixel, and the applied voltage of the fourth pixel adjacent to the side opposite to the boundary when viewed from the second pixel. Before the voltage difference becomes smaller Correcting the video data, the applied voltage of the fifth pixel adjacent to the side opposite to the boundary when viewed from the third pixel and the voltage of the sixth pixel adjacent to the side opposite to the boundary viewed from the fourth pixel And a correction unit that corrects the video data so that a voltage difference from the applied voltage becomes large.
According to this configuration, it is possible to suppress the occurrence of disclination and to prevent a decrease in contrast in a portion having a gradation difference.

  In addition to the image processing circuit, the present invention can also be conceptualized as an image processing method and an electronic apparatus including the electro-optical device.

1 is a block diagram showing the overall configuration of an electro-optical device 1. FIG. FIG. 4 shows a configuration of a display panel 100. FIG. 6 shows a configuration of a pixel 110. FIG. 6 is a diagram showing a relationship between applied voltage and transmittance in the liquid crystal element 120. The figure for demonstrating operation | movement of 1st Embodiment. The figure for demonstrating operation | movement of 2nd Embodiment. The figure for demonstrating operation | movement of 3rd Embodiment. FIG. 3 is a diagram illustrating a configuration of a projector using the electro-optical device according to the embodiment. The figure for demonstrating the operation | movement of a modification. The figure for demonstrating the operation | movement of a modification. The figure for demonstrating the operation | movement of a modification. The figure for demonstrating the operation | movement of a modification.

[First Embodiment]
FIG. 1 is a block diagram showing an overall configuration of an electro-optical device 1 according to the first embodiment of the present invention. As shown in FIG. 1, the configuration of the electro-optical device 1 is roughly divided into a timing control circuit 10, a display panel 100, and an image processing circuit 20.
The timing control circuit 10 generates various control signals in synchronization with a synchronization signal Sync given from an external device (not shown), and controls each part of the electro-optical device 1.
The image processing circuit 20 is a circuit that processes a signal supplied to the display panel 100. Image data Da-in is supplied to the image processing circuit 20 from an external device in synchronization with the synchronization signal Sync. The video data Da-in is digital data that designates the gradation value of each pixel of a plurality of pixels (a display area 101 described later) included in the display panel 100. The gradation value is a parameter that defines the brightness of the pixel. Here, the video data Da-in is set to 8 bits, and the gradation to be expressed by the pixel is designated with 256 gradations in increments of “1” from the darkest “0” to the brightest “255”. ing. The video data Da-in is supplied in the order of scanning according to the vertical scanning signal, horizontal scanning signal, and dot clock signal (all not shown) included in the synchronization signal Sync. The image processing circuit 20 processes the video data Da-in and outputs correction data Da-out to the display panel 100. The video data Da-in designates the gradation value of each pixel of the display panel 100. Since the voltage applied to the liquid crystal element of the pixel is determined according to the gradation value, the video data Da- It can be said that in designates the voltage applied to the liquid crystal element.
The display panel 100 is an active matrix display device in which each pixel is driven by a switching element such as a transistor, for example. The display panel 100 displays an image based on the correction data Da-out supplied from the image processing circuit 20.

  FIG. 2 is a diagram illustrating a configuration of the display panel 100. As shown in FIG. 2, in the display area 101 where an image is displayed in the display panel 100, 1, 2, 3,..., M rows of scanning lines 112 are provided along the X direction. In the display area 101, 1, 2, 3,..., N columns of data lines 114 are provided along the Y direction orthogonal to the scanning lines 112. Each data line 114 and each scanning line 112 are provided so as to be electrically insulated from each other. The pixels 110 are provided corresponding to the intersections of the m rows of scanning lines 112 and the n columns of data lines 114, respectively. Therefore, in this embodiment, in the display area 101, the pixels 110 are arranged in a matrix with m rows × n columns.

Around the display area 101, a scanning line driving circuit 130 and a data line driving circuit 140 are arranged.
The scanning line driving circuit 130 selects the scanning line 112 specified by the control signal Yctr supplied from the timing control circuit 10. The scanning line driving circuit 130 sets the scanning signal for the selected scanning line 112 to the H (High) level corresponding to the selection voltage, while setting the scanning signal for the other scanning lines 112 to the L (Low) level corresponding to the non-selection voltage. And In FIG. 2, the scanning signals supplied to the scanning lines 112 in the first, second, third,..., M-th rows are denoted as G1, G2, G3,.
The data line driving circuit 140 drives the pixel 110 by a so-called voltage modulation method based on the correction data Da-out. Specifically, the data line driving circuit 140 applies voltage data having a magnitude corresponding to the correction data Da-out to the data lines 114 in the first to nth columns in accordance with the control signal Xctr supplied from the timing control circuit 10. Supply signal.
The pixel 110 has a liquid crystal element in which a liquid crystal is sandwiched between a pixel electrode and a common electrode, and a data signal supplied to the data line 114 is applied to the pixel electrode when the scanning line 112 is selected. .

FIG. 3 is a diagram showing an equivalent circuit of the display panel 100. As shown in FIG. 3, the display panel 100 has a configuration in which liquid crystal elements 120 each having a liquid crystal 105 sandwiched between a pixel electrode 118 and a common electrode 108 are arranged corresponding to the intersection of a scanning line 112 and a data line 114. is there. In the equivalent circuit of the display panel 100, an auxiliary capacitor (storage capacitor) 125 is provided in parallel with the liquid crystal element 120. The auxiliary capacitor 125 has one end connected to the pixel electrode 118 and the other end commonly connected to the capacitor line 115. Note that the capacitor line 115 is maintained at a constant voltage over time.
In the configuration shown in FIG. 3, when the scanning line 112 becomes H level, a TFT (Thin Film Transistor) 116 whose gate electrode is connected to the scanning line is turned on, and the pixel electrode 118 is connected to the data line 114. Therefore, when the data signal is supplied to the data line 114 when the scanning line 112 is at the H level, the data signal is supplied to the pixel electrode 118 through the TFT 116 which is turned on. When the scanning line 112 becomes L level, the TFT 116 is turned off, but the voltage applied to the pixel electrode 118 is held by the capacitive element of the liquid crystal element 120 and the auxiliary capacitor 125.
In the liquid crystal element 120, the molecular alignment state of the liquid crystal 105 changes according to the electric field generated by the pixel electrode 118 and the common electrode 108. For this reason, if the liquid crystal element 120 is a transmission type, it has a transmittance corresponding to the applied / holding voltage. In the display panel 100, since the transmittance varies for each liquid crystal element 120, each of the pixels 110 includes the liquid crystal element 120. In the present embodiment, the liquid crystal 105 is set to a VA (Vertical Alignment) system, which is a normally black mode in which the liquid crystal element 120 is in a black state when no voltage is applied.

  FIG. 4 is a graph showing a curve representing the relationship between the applied voltage and the transmittance in the normally black mode liquid crystal element 120. In the graph shown in FIG. 4, the horizontal axis corresponds to the magnitude of the voltage applied to the liquid crystal element 120, and the vertical axis corresponds to the magnitude of the transmittance (specifically, relative transmittance) of the liquid crystal element 120. Yes. In order to make the liquid crystal element 120 have a transmittance corresponding to the gradation value specified by the video data Da-in, a voltage having a magnitude corresponding to the gradation value may be applied to the liquid crystal element 120. In the normally black mode, the voltage to be applied to the liquid crystal element 120 increases as the gradation value increases.

In order to prevent the deterioration of the liquid crystal 105, the liquid crystal element 120 is basically driven in alternating current in the display panel 100. However, when the liquid crystal element 120 is driven in alternating current, the liquid crystal element 120 is expressed so as to express a certain gradation. Are driven, two types are required: a positive polarity that is higher than the amplitude center voltage, and a negative polarity that is lower than the amplitude center voltage.
For the voltages of the embodiments, except for the voltage applied to the liquid crystal element 120, the ground potential not shown is used as a reference for zero voltage unless otherwise specified. The voltage applied to the liquid crystal element 120 is a potential difference between the voltage LCcom of the common electrode 108 and the pixel electrode 118. When the liquid crystal element 120 holds the voltage corresponding to the gradation, when the writing polarity is positive, the potential of the pixel electrode 118 is higher than the voltage LCcom of the common electrode 108, and the writing polarity is negative. In this case, the potential of the pixel electrode 118 is lower than the voltage LCcom of the common electrode 108.

By the way, when the difference in the applied voltage to the liquid crystal element 120 is greater than or equal to a predetermined threshold value between adjacent pixels, the lateral electric field becomes strong due to this applied voltage difference, and disclination may occur. . Among these pixels, the pixel on the low gradation side may indicate a black state near the minimum gradation or a state close to the black state, or may indicate a relatively bright state near the intermediate gradation. On the other hand, the pixel on the high gradation side may indicate a brightness state near the intermediate gradation, or may indicate a white state near the maximum gradation or a state close to the white state. Thus, disclination occurs due to a potential difference between adjacent pixels, but the brightness around the generation region varies.
In the present embodiment, a pixel in which a voltage applied to a pixel is lower than a predetermined first threshold value Vth1 (first voltage) (a pixel whose gradation value is lower than a predetermined first threshold value Cth1) is a dark pixel, A pixel in which the voltage applied to the pixel exceeds a predetermined second threshold Vth2 (second threshold Vth2> first threshold Vth1) (a pixel whose gradation value exceeds a predetermined second threshold Cth2) is defined as a bright pixel. The boundary between adjacent dark pixels and bright pixels is defined as a boundary where disclination occurs.

  Next, the configuration of the image processing circuit 20 will be described with reference to FIG. The image processing circuit 20 includes a conversion unit 21, a frame memory 22, a boundary detection unit 23, and a correction unit 24. The conversion unit 21 acquires video data Da-in supplied from an external device. The conversion unit 21 obtains a voltage to be applied to the pixel 110 when changing the gradation of the pixel to the gradation represented by the video data Da-in. The converter 21 outputs voltage data DV1 representing the obtained voltage. Specifically, the conversion unit 21 includes a table in which the gradation value is associated with the voltage value applied to the pixel when the gradation value is set, and the video data Da-in is used using this table. Find the voltage from In this table, the voltage may be a normalized value so that the calculation described later is easy.

  The frame memory 22 has a storage area corresponding to a pixel array of vertical m rows × horizontal n columns corresponding to the display area 101, and receives one frame (one frame) of voltage data DV 1 supplied from the conversion unit 21. Remember. Each storage area stores voltage data DV1 indicating a voltage to be applied to the corresponding pixel 110. Here, the frame refers to a period required to display one frame of an image by driving the display panel 100. For example, if the frequency of the vertical scanning signal included in the synchronization signal Sync is 60 Hz, the period is 16.7 milliseconds which is the reciprocal thereof. Note that the writing of the voltage data DV1 to the frame memory 22 and the reading of the voltage data DV1 from the frame memory 22 are, for example, a memory (not shown) according to the drive timing in the display panel 100 under the control of the timing control circuit 10. Performed by the controller.

The boundary detection unit 23 analyzes the voltage data DV1 of a plurality of pixels with reference to the frame memory 22, and the difference between applied voltages applied to two adjacent pixels is equal to or greater than a threshold value (that is, disclination occurs). Detect a boundary (which is a possible applied voltage difference).
Specifically, the boundary detection unit 23 applies the voltage applied to one pixel below the first threshold value Vth1 in two pixels adjacent in the X direction shown in FIG. When the voltage applied to the pixel exceeds the second threshold value Vth2, a detection is made between the two pixels as a boundary. Note that, for the first threshold value Vth1 and the second threshold value Vth2, for example, values obtained experimentally are set in the image processing circuit 20. Further, the boundary detection unit 23 applies the voltage applied to one pixel below the first threshold value in the two pixels adjacent in the Y direction shown in FIG. 2 based on the voltage data DV1, and applied to the other pixel. When the voltage exceeds the second threshold value, a detection is made between the two pixels as a boundary. When detecting the boundary, the boundary detection unit 23 outputs position information Pos indicating the position of the detected boundary.
Since the voltage data DV1 corresponds to the gradation of the pixel, the boundary detection unit 23 corresponds to the pixel below the gradation corresponding to the first threshold Vth1 (first gradation) and the second threshold Vth2. It can be said that a boundary between pixels exceeding the gradation (second gradation) is detected as a boundary.

The correction unit 24 includes a voltage difference calculation unit 25 and a correction value calculation unit 26. Based on the voltage data DV1 read from the frame memory 22, the voltage difference calculation unit 25 applies the voltage applied to one of the two pixels adjacent to the position represented by the position information Pos and the voltage applied to the other pixel. A voltage difference ΔV from the applied voltage is calculated. Here, the voltage difference calculation unit 25 calculates the voltage difference ΔV by subtracting the applied voltage to the low potential side pixel from the applied voltage to the high potential side pixel. The greater the voltage difference ΔV, the greater the difference between the voltage applied to the pixel electrode 118 of one adjacent pixel and the voltage applied to the pixel electrode 118 of the other pixel.
The correction value calculation unit 26 has a memory for storing a predetermined first correction coefficient α, and calculates the correction value ΔRE1 by multiplying the voltage difference ΔV calculated by the voltage difference calculation unit 25 by the first correction coefficient α. To do.

  The correction unit 24 corrects the voltage data DV1 of the pixel adjacent to the boundary, and outputs the voltage data obtained by the correction as correction data Da-out. Specifically, for the bright pixel (second pixel) among the pixels adjacent to the boundary at the position indicated by the position information Pos, the correcting unit 24 applies the voltage data DV1 when applying a positive voltage to the pixel. When the negative voltage is applied to the pixel as a result of subtracting the correction value ΔRE1 from the applied voltage, the result of adding the correction value ΔRE1 to the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage Is output. In addition, for the dark pixel (first pixel) among the pixels adjacent to the boundary at the position indicated by the position information Pos, the correction unit 24 applies a correction value to the voltage data DV1 when a positive voltage is applied to the pixel. When applying the result of adding ΔRE1 as an applied voltage and applying a negative voltage to the pixel, the result of subtracting the correction value ΔRE1 from the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage is output. .

In addition, for the second pixel (fourth pixel) counted from the boundary to the bright pixel side, the correction unit 24 applies a predetermined correction value ΔRE2 to the voltage data DV1 when applying a positive voltage to the pixel. When the addition result is used as an applied voltage and a negative voltage is applied to the pixel, the result obtained by subtracting the correction value ΔRE2 from the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage is output. The correction unit 24 subtracts the correction value ΔRE2 from the voltage data DV1 when a positive voltage is applied to the second pixel (third pixel) counted from the boundary to the dark pixel side. Is applied voltage, and a negative voltage is applied to the pixel, the result obtained by adding the correction value ΔRE2 to the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage is output.
Note that the correction unit 24 outputs the corrected data Da-out without correcting the voltage data DV1 for pixels that are not in contact with the boundary.

(Operation example of the first embodiment)
Subsequently, an operation example of the first embodiment will be described. FIG. 5 shows the correspondence between 10 pixels arranged in one direction (for example, the X direction in FIG. 2) in the display area 101 and the applied voltages of these pixels. FIG. 5 shows the case of positive polarity writing. FIG. 5A is a diagram showing a correspondence relationship when the correction processing is not performed (or before the correction processing), and FIG. 5B shows a correspondence relationship after the correction processing by the correction unit 24. FIG. In the following description, the voltage applied to the pixel a which is a dark pixel is lower than the first threshold Vth1 and the voltage applied to the pixel b which is a bright pixel is higher than the second threshold Vth2 before the correction process. And

  If the correction unit 24 is configured not to correct the voltage data DV1, as shown in FIG. 5A, the potential difference between the pixel a and the pixel b is large, so the adjacent pixels a and b In the vicinity of the boundary portion, the region is easily affected by a lateral electric field and becomes a disclination generation region. When the applied voltage to the pixel is negative, the applied voltage to each pixel is symmetric with respect to applying a positive voltage with respect to the common electrode voltage, and the magnitude relation of the potential is reversed. However, since there is no change in the potential difference, the vicinity of the boundary between the dark pixel and the bright pixel is the disclination generation region.

  The correction unit 24 performs correction processing so that such a disclination occurrence area does not appear. Specifically, when the video data Da-in is supplied to the image processing circuit 20, the conversion unit 21 outputs voltage data DV1 representing the voltage applied to each pixel. The voltage data DV1 of each pixel output from the conversion unit 21 is stored in the frame memory 22.

The boundary detection unit 23 refers to the voltage data DV1 stored in the frame memory 22 and detects the boundary. For example, for the first pixel a from the left and the second pixel a from the left adjacent to each other in the X direction, the boundary detection unit 23 causes the voltage data DV1 to be lower than the first threshold Vth1 and higher than the second threshold Vth2. Therefore, these pixels are not detected as boundaries.
On the other hand, for the fifth pixel a from the left and the sixth pixel b from the left adjacent to each other in the X direction, the voltage data DV1 of the pixel a is below the first threshold value Vth1, and the voltage data DV1 of the pixel b is the second voltage data DV1. Since it exceeds the threshold value Vth2, between these pixels is detected as a boundary, and position information Pos indicating the position of the detected boundary is output.

  The correction unit 24 acquires the position information Pos and corrects the voltage data DV1 supplied from the frame memory 22. For example, as described above, when the boundary between the fifth pixel a from the left and the sixth pixel b from the left is the boundary in the X direction, the voltage difference calculation unit 25 applies the applied voltage to the pixel a. And a voltage difference ΔV from the voltage applied to the pixel b is calculated. The correction value calculator 26 calculates the correction value ΔRE1 by multiplying the voltage difference ΔV calculated by the voltage difference calculator 25 by the first correction coefficient α. Then, the correction unit 24 sets the applied voltage (voltage Va1) as a result of adding the correction value ΔRE1 to the voltage data DV1 for the dark pixel among the two pixels adjacent to the boundary, and the correction data Da− representing this voltage. out is output. Further, for the bright pixel adjacent to the boundary, the correction unit 24 sets the applied voltage (voltage Vb1) as a result of subtracting the correction value ΔRE1 from the voltage data DV1, and outputs correction data Da-out representing this voltage.

  The correction unit 24 applies the result of subtracting the correction value ΔRE2 from the voltage data DV1 for the second pixel (fourth pixel from the left in FIG. 5A) counting from the boundary to the dark pixel side. The voltage (voltage Va2) is used, and correction data Da-out representing this voltage is output. Further, the correction unit 24 applies the result of adding the correction value ΔRE2 to the voltage data DV1 for the second pixel (fourth pixel from the right in FIG. 5A) counting from the boundary to the bright pixel side. The voltage (voltage Vb2) is used, and correction data Da-out representing this voltage is output.

  As a result, as shown in FIG. 5B, since the difference in applied voltage between the corrected pixel a1 and the corrected pixel b1 is reduced, the generation of a lateral electric field is suppressed, and disclination is prevented. Occurrence is suppressed. Further, since the corrected pixel a2 adjacent to the pixel a1 is corrected so that the applied voltage is low, the gradation is low, and the corrected pixel b2 adjacent to the pixel b1 is high in applied voltage. Since the correction is made, the gradation becomes higher. In other words, since the gradation difference between pixels separated by one pixel from the boundary becomes larger than before correction, it is possible to suppress a decrease in contrast of a portion serving as an outline in a displayed image.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The electro-optical device 1 according to the second embodiment differs from the first embodiment in the operation of the correction unit 24. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals, the description thereof will be omitted, and differences from the first embodiment will be mainly described.

The correction unit 24 according to the second embodiment applies a predetermined correction from the voltage data DV1 when a positive voltage is applied to the third pixel (sixth pixel) from the boundary to the bright pixel side. When applying the result of adding the value ΔRE3 as an applied voltage and applying a negative voltage to the pixel, the result obtained by subtracting the correction value ΔRE3 from the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage is output. To do.
The correction unit 24 subtracts the correction value ΔRE3 from the voltage data DV1 when applying a positive voltage to the third pixel (fifth pixel) from the boundary to the dark pixel side. When applying a negative voltage to the pixel as an applied voltage, a result obtained by adding the correction value ΔRE3 to the voltage data DV1 is used as an applied voltage, and correction data Da-out representing this applied voltage is output.

  Next, an operation example of the second embodiment will be described. FIG. 6 is a diagram showing a voltage applied to the pixel when the correction process is performed when the state before correction is the state shown in FIG. When the video data Da-in is supplied to the image processing circuit 20, the boundary detection unit 23, as in the first embodiment, is the fifth pixel a from the left adjacent in the X direction shown in FIG. And the sixth pixel from the left is detected as a boundary, and position information Pos indicating the position of the detected boundary is output.

  The correction unit 24 acquires the position information Pos and corrects the voltage data DV1 supplied from the frame memory 22. The correction unit 24 corrects the voltage data DV1 in the same manner as in the first embodiment for dark pixels and bright pixels adjacent to the boundary, and outputs correction data Da-out representing the corrected voltage. The correction unit 24 also corrects the voltage data DV1 in the same manner as in the first embodiment for the second pixel counted from the boundary to the bright pixel side and the second pixel counted from the boundary to the dark pixel side. The correction data Da-out representing the corrected voltage is output.

  Further, the correction unit 24 applies the result of subtracting the correction value ΔRE3 from the voltage data DV1 for the third pixel (third pixel a from the left in FIG. 5A) counting from the boundary to the dark pixel side. The voltage (voltage Va3) is used, and correction data Da-out representing this voltage is output. The correction unit 24 applies the result of adding the correction value ΔRE3 to the voltage data DV1 for the third pixel (the third pixel b from the right in FIG. 5A) counting from the boundary to the bright pixel side. The voltage (voltage Vb3) is used, and correction data Da-out representing this voltage is output.

  As a result, as shown in FIG. 6, since the difference in applied voltage between the corrected pixel a1 and pixel b1 is reduced, the generation of a lateral electric field is suppressed and the occurrence of disclination is suppressed. In addition, the corrected pixel a2 adjacent to the pixel a1 is corrected so that the applied voltage is low, so that the gradation is low, and the corrected pixel b2 adjacent to the pixel b1 is high in applied voltage. Therefore, the gradation is increased. Further, since the corrected pixel a3 adjacent to the pixel a2 is corrected so that the applied voltage is low, the gradation is lowered, and the corrected pixel b3 adjacent to the pixel b2 is increased in applied voltage. Therefore, the gradation is increased. In other words, since the gradation difference between the pixels separated by one pixel from the boundary and the pixels separated by two pixels from the boundary is larger than before the correction, it is possible to suppress a decrease in the contrast of the contour portion in the displayed image. be able to.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The electro-optical device 1 according to the third embodiment is different from the first embodiment in the operation of the correction unit 24. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals, the description thereof will be omitted, and differences from the first embodiment will be mainly described.

The correction unit 24 according to the third embodiment applies a predetermined correction from the voltage data DV1 when a positive voltage is applied to the second pixel (fourth pixel) from the boundary to the bright pixel side. When applying the result of subtracting the value ΔRE4 as the applied voltage and applying a negative voltage to the pixel, the result obtained by adding the correction value ΔRE4 to the voltage data DV1 is used as the applied voltage, and correction data Da-out representing this applied voltage is output. To do. The correction unit 24 adds the correction value ΔRE4 to the voltage data DV1 when applying a positive voltage to the second pixel (third pixel) from the boundary to the dark pixel side. When applying a negative voltage to the pixel as an applied voltage, a result obtained by subtracting the correction value ΔRE4 from the voltage data DV1 is used as an applied voltage, and correction data Da-out representing this applied voltage is output.
Further, when applying a positive voltage to the third pixel (sixth pixel) from the boundary to the bright pixel side, the correction unit 24 applies the result of adding the correction value ΔRE2 to the voltage data DV1. When a negative voltage is applied to the pixel, a result obtained by subtracting a predetermined correction value ΔRE2 from the voltage data DV1 is used as an applied voltage, and correction data Da-out representing this applied voltage is output. The correction unit 24 subtracts the correction value ΔRE2 from the voltage data DV1 when applying a positive voltage to the third pixel (fifth pixel) from the boundary to the dark pixel side. When applying a negative voltage to the pixel as an applied voltage, a result obtained by adding the correction value ΔRE2 to the voltage data DV1 is used as an applied voltage, and correction data Da-out representing this applied voltage is output.

  Next, an operation example of the third embodiment will be described. FIG. 7 is a diagram showing the voltage applied to the pixel when the correction process is performed when the state before correction is the state shown in FIG. When the video data Da-in is supplied to the image processing circuit 20, the boundary detection unit 23, as in the first embodiment, is the fifth pixel a from the left adjacent in the X direction shown in FIG. And the sixth pixel from the left is detected as a boundary, and position information Pos indicating the position of the detected boundary is output.

  The correction unit 24 acquires the position information Pos and corrects the voltage data DV1 supplied from the frame memory 22. The correction unit 24 corrects the voltage data DV1 in the same manner as in the first embodiment for dark pixels and bright pixels adjacent to the boundary, and outputs correction data Da-out representing the corrected voltage.

  The correction unit 24 applies the result of adding the correction value ΔRE4 to the voltage data DV1 for the second pixel (fourth pixel a from the left in FIG. 5A) counting from the boundary to the dark pixel side. The voltage (voltage Va4) is used, and correction data Da-out representing this voltage is output. Further, the correction unit 24 subtracts the correction value ΔRE4 from the voltage data DV1 for the second pixel b (fourth pixel b from the right in FIG. 5A) counted from the boundary to the bright pixel side. The applied data (voltage Vb4) is output, and correction data Da-out representing this voltage is output.

  The correction unit 24 applies the result of subtracting the correction value ΔRE2 from the voltage data DV1 for the third pixel (the third pixel a from the left in FIG. 5A) counting from the boundary to the dark pixel side. The voltage (voltage Va2) is used, and correction data Da-out representing this voltage is output. Further, the correction unit 24 applies the result of adding the correction value ΔRE2 to the voltage data DV1 for the third pixel (the third pixel b from the right in FIG. 5A) counted from the boundary to the bright pixel side. The voltage (voltage Vb2) is used, and correction data Da-out representing this voltage is output.

  As a result, as shown in FIG. 7, since the difference in applied voltage between the corrected pixel a1 and pixel b1 is reduced, the generation of a lateral electric field is suppressed, and the occurrence of disclination is suppressed. Further, the corrected pixel a2 adjacent to the pixel a1 is corrected so that the applied voltage is increased, so that the gradation is increased, and the corrected pixel b2 adjacent to the pixel b1 is decreased in applied voltage. Therefore, the gradation is lowered. Further, since the corrected pixel a3 adjacent to the pixel a2 is corrected so that the applied voltage is low, the gradation is lowered, and the corrected pixel b3 adjacent to the pixel b2 is increased in applied voltage. Therefore, the gradation is increased. That is, the pixel adjacent to the boundary and the pixel separated by one pixel from the boundary have a smaller gradation difference than before the correction, and the pixels separated by two pixels from the boundary have a larger gradation difference than before the correction. Therefore, it is possible to suppress a decrease in contrast of a portion that becomes an outline in the displayed image.

[Electronics]
Next, a projector using the display panel 100 of the electro-optical device 1 as a light valve will be described as an example of an electronic apparatus using the electro-optical device 1 described above. FIG. 8 is a plan view showing the configuration of the projector.
As shown in this figure, a projector 2100 is provided with a lamp unit 2102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 2102 is provided with three primary colors of R (red), G (green), and B (blue) by three mirrors 2106 and two dichroic mirrors 2108 disposed therein. And led to the light valves 100R, 100G and 100B corresponding to the respective primary colors. Note that B light has a longer optical path than other R and G colors, and therefore, in order to prevent the loss, B light passes through a relay lens system 2121 including an incident lens 2122, a relay lens 2123, and an exit lens 2124. Led.

In the projector 2100, three sets of electro-optical devices 1 including the display panel 100 are provided corresponding to each of R color, G color, and B color. The video data Da-in corresponding to each of the R, G, and B colors is supplied from the upper circuit. The configuration of the light valves 100R, 100G, and 100B is the same as that of the display panel 100 described above, and is driven according to the video data Da-in corresponding to each of the R color, G color, and B color. .
The lights modulated by the light valves 100R, 100G, and 100B are incident on the dichroic prism 2112 from three directions. In the dichroic prism 2112, the R and B light beams are refracted at 90 degrees, while the G light beam travels straight. Therefore, after the images of the respective colors are combined, a color image is projected onto the screen 2120 by the projection lens 2114.

  Since light corresponding to each of R color, G color, and B color is incident on the light valves 100R, 100G, and 100B by the dichroic mirror 2108, it is not necessary to provide a color filter. In addition, the transmission images of the light valves 100R and 100B are projected after being reflected by the dichroic prism 2112, whereas the transmission image of the light valve 100G is projected as it is, so the horizontal scanning direction by the light valves 100R and 100B is The image is reversed in the horizontal scanning direction by the light valve 100G and displayed in an inverted image.

  In addition to the electronic devices described with reference to FIG. 8, the electronic devices include a television, a viewfinder type / direct monitor type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a television. Examples include a telephone, a POS terminal, a digital still camera, a mobile phone, and a device equipped with a touch panel. The electro-optical device may be applied to these various electronic devices.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows. In addition, you may combine each of embodiment mentioned above and the following modifications.

In the embodiment described above, the liquid crystal element 120 is normally black, but may be normally white. In the above-described embodiment, the display panel 100 is a transmissive liquid crystal display panel, but may be a reflective liquid crystal display panel.
When the liquid crystal element 120 is normally white, the relationship between addition and subtraction of the correction value is opposite to that of normally black. For example, for a dark pixel, the correction value is subtracted from the voltage data DV1 when applying a positive polarity voltage to reduce the gradation difference, and the voltage data DV1 is corrected when applying a negative voltage. Add the values. For a bright pixel, when a gradation difference is reduced, a correction value is added to voltage data DV1 when a positive voltage is applied, and correction is performed from voltage data DV1 when a negative voltage is applied. Subtract the value.

  In the above-described embodiment, the third pixel counting from the boundary is corrected, so that three pixels below the first threshold are consecutive from the boundary and three pixels above the second threshold are consecutive from the boundary. As described above, the voltage data DV1 may be corrected.

In the above-described embodiment, the voltage data DV1 is corrected for both of the two pixels adjacent to the boundary. However, the present invention is not limited to this configuration.
For example, when the state shown in FIG. 5A is corrected, as shown in FIG. 9, the voltage applied to the bright pixel adjacent to the boundary is corrected to be lowered and applied to the dark pixel adjacent to the boundary. Do not correct the voltage. In addition, the applied voltage is not corrected for the second and subsequent pixels counted from the boundary to the bright pixel side, and the applied voltage is corrected to be lowered for the second pixel counted from the boundary to the dark pixel side. The applied voltage is not corrected for the third pixel counted from the boundary to the dark pixel side. Note that the potential difference between pixels adjacent to the boundary is preferably set to be less than the difference between the first threshold value Vth1 and the second threshold value Vth2 after correction.

  Further, in the configuration in which the applied voltage is not corrected for both the pixels adjacent to the boundary, for example, when the state illustrated in FIG. 5A is corrected, as illustrated in FIG. The voltage applied to the matching dark pixel is corrected to increase, the voltage applied to the bright pixel adjacent to the boundary is not corrected, and the voltage applied to the second and subsequent pixels from the boundary to the dark pixel side is corrected. Is corrected so that the applied voltage is increased for the second pixel counted from the boundary to the bright pixel side, and the applied voltage is applied to the third pixel counted from the boundary to the bright pixel side. You may make it not correct | amend. In this modification as well, it is preferable that the potential difference between the pixels adjacent to the boundary is less than the difference between the first threshold value Vth1 and the second threshold value Vth2 after correction.

Further, in the configuration in which the voltage data DV1 is corrected for both of the two pixels adjacent to the boundary, for example, when the state illustrated in FIG. 5A is corrected, the boundary as illustrated in FIG. The correction may be made so that the applied voltage is lowered for the second pixel counting from the dark side to the dark pixel side, and the applied voltage may not be corrected for the second pixel counting from the boundary to the bright pixel side. .
Further, for example, when the state shown in FIG. 5A is corrected, as shown in FIG. 12, the correction is performed so that the applied voltage is increased for the second pixel counted from the boundary to the bright pixel side. The applied voltage may not be corrected for the second pixel counted from the boundary to the dark pixel side.

  In the configuration for correcting the voltage applied to the third pixel counted from the boundary as in the second embodiment and the third embodiment, the third pixel counted from the boundary to the bright pixel side. The voltage applied may be corrected, and the voltage applied to the third pixel counted from the boundary to the dark pixel side may not be corrected. Further, in the configuration in which the voltage applied to the third pixel counted from the boundary is corrected, the voltage applied to the third pixel counted from the boundary to the dark pixel side is corrected, and the bright pixel from the boundary is corrected. For the third pixel counted to the side, the applied voltage may not be corrected.

  In the second and third embodiments, the applied voltage is not corrected for the second and third pixels counted from the boundary to the dark pixel side, or counted from the boundary to the bright pixel side. For the second and third pixels, the applied voltage may not be corrected.

The correction unit 24 may determine the correction amount of the voltage to be applied in accordance with the relationship between the voltage applied to the liquid crystal element 120 and the transmittance.
For example, according to the VT curve representing the relationship between the voltage applied to the liquid crystal element 120 and the transmittance, the liquid crystal element 120 changes the applied voltage in the range close to the lowest gradation or the highest gradation. Is large, the gradation change is small, and in the intermediate gradation range, the gradation change is large even if the applied voltage is small. Therefore, for the second pixel and the third pixel counted from the boundary, the correction amount is increased when the pixel gradation is a dark pixel and close to the lowest gradation, and the pixel gradation is a dark pixel. If the value is close to the first threshold, the correction amount may be reduced. In addition, for the second pixel and the third pixel counted from the boundary, when the pixel gradation is a bright pixel and close to the maximum gradation, the correction amount is increased, and the pixel gradation is a bright pixel. If it is close to the second threshold, the correction amount may be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 10 ... Timing control circuit, 20 ... Image processing circuit, 21 ... Conversion part, 22 ... Frame memory, 23 ... Boundary detection part, 24 ... Correction part, 25 ... Voltage difference calculating part, 26 ... Correction value Arithmetic unit, 100 ... display panel, 101 ... display area, 105 ... liquid crystal, 110 ... pixel, 112 ... scanning line, 114 ... data line, 120 ... liquid crystal element, 130 ... scanning line driving circuit, 140 ... data line driving circuit, 2100 ... Projector

Claims (10)

An image processing circuit that inputs video data specifying an applied voltage for each pixel and that defines an applied voltage of the pixel by correction data obtained by correcting the video data,
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. A boundary detection unit that
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. A correction unit that corrects the video data so that a voltage difference between an applied voltage and an applied voltage of a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is increased;
An image processing circuit. The correction unit is
The image processing circuit according to claim 1, wherein the applied voltage of the third pixel is corrected and the applied voltage of the fourth pixel is corrected. The correction unit is
The voltage difference between the applied voltage of the fifth pixel adjacent to the side opposite to the boundary as viewed from the third pixel and the applied voltage of the sixth pixel adjacent to the side opposite to the boundary as viewed from the fourth pixel. The image processing circuit according to claim 2, wherein the video data is corrected so as to increase. An image processing circuit that inputs video data specifying an applied voltage for each pixel and that defines an applied voltage of the pixel by correction data obtained by correcting the video data,
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. A boundary detection unit that
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. The video data is corrected so that a voltage difference between an applied voltage and an applied voltage of a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is reduced, and the boundary when viewed from the third pixel. The video data is adjusted so that a voltage difference between an applied voltage of the fifth pixel adjacent to the opposite side of the fourth pixel and an applied voltage of the sixth pixel adjacent to the opposite side of the boundary when viewed from the fourth pixel is increased. A correction unit to correct,
An image processing circuit.   The image processing circuit according to claim 3, wherein the correction unit varies the amount of correction for the third pixel to the sixth pixel according to an applied voltage represented by the video data. A plurality of pixels;
Image data specifying an applied voltage for each pixel is input, and has an image processing circuit that defines an applied voltage of each pixel by correction data obtained by correcting the video data,
The image processing circuit includes:
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. A boundary detection unit that
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. A correction unit that corrects the video data so that a voltage difference between an applied voltage and an applied voltage of a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is increased;
An electro-optical device. A plurality of pixels;
Image data specifying an applied voltage for each pixel is input, and has an image processing circuit that defines an applied voltage of each pixel by correction data obtained by correcting the video data,
The image processing circuit includes:
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. A boundary detection unit that
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. The video data is corrected so that a voltage difference between an applied voltage and an applied voltage of a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is reduced, and the boundary when viewed from the third pixel. The video data is adjusted so that a voltage difference between an applied voltage of the fifth pixel adjacent to the opposite side of the fourth pixel and an applied voltage of the sixth pixel adjacent to the opposite side of the boundary when viewed from the fourth pixel is increased. A correction unit to correct,
An electro-optical device. An image processing method for defining an applied voltage of each pixel by correction data obtained by correcting video data specifying an applied voltage for each pixel,
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. And
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. An image processing method for correcting the video data so that a voltage difference between an applied voltage and a voltage applied to a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is increased. An image processing method for defining an applied voltage of each pixel by correction data obtained by correcting video data specifying an applied voltage for each pixel,
Detects a boundary between a first pixel whose applied voltage specified by the video data is lower than a first threshold and a second pixel whose applied voltage specified by the video data is higher than a second threshold higher than the first threshold. A boundary detection unit that
The video data is corrected so as to reduce a lateral electric field generated between the first pixel and the second pixel adjacent to the boundary, and a third pixel adjacent to the side opposite to the boundary as viewed from the first pixel is corrected. The video data is corrected so that a voltage difference between an applied voltage and an applied voltage of a fourth pixel adjacent to the opposite side of the boundary when viewed from the second pixel is reduced, and the boundary when viewed from the third pixel. The video data is adjusted so that a voltage difference between an applied voltage of the fifth pixel adjacent to the opposite side of the fourth pixel and an applied voltage of the sixth pixel adjacent to the opposite side of the boundary when viewed from the fourth pixel is increased. Image processing method to be corrected.   An electronic apparatus comprising the electro-optical device according to claim 6.