JP6340931B2 - Electro-optical panel driving method, electro-optical device, and electronic apparatus - Google Patents

Description

  The present invention relates to an electro-optical device, a driving method of the electro-optical device, and an electronic apparatus.

  In an electro-optical device that displays an image using an electro-optical element such as a liquid crystal element or an organic EL (Electro-Luminescence) element, for each of a plurality of subfield periods obtained by dividing a frame period that is a unit of an operation period of the electro-optical device In addition, there has been proposed a technique for expressing an intermediate gradation by driving an electro-optical element in either an on state or an off state and changing a ratio of time for driving in an on state or an off state (patent). Reference 1).

JP 2003-114661 A

Incidentally, an image display system for displaying 3D is known. In this image display system, a user wears stereoscopic glasses having a left-eye shutter and a right-eye shutter, displays a left-eye image on a display device in a certain frame period, and then displays the next frame. The right eye image is displayed during the period. In this case, since the time length of the frame period is halved compared to 2D display, the number of subfield periods that can be used in one frame period is halved. As a result, the 3D display has a problem that gradation is deteriorated.
Further, in 3D display, it is necessary to scan the scanning line at a double speed compared with 2D display, so the time length of the horizontal scanning period is shortened. In particular, in the weighted subfield driving method in which the time length is different for each subfield period, it is necessary to select a plurality of scanning lines in a time division manner and write data signals to the pixels in one horizontal scanning period. As described above, when the time length of the horizontal scanning period is shortened, the number of scanning lines that can be selected in one horizontal scanning period is also reduced. As a result, there is a problem that variations in the subfield period are lowered, and as a result, the gradation is lowered. Such an inconvenience is not limited to 3D display, but is the same when the frame period is shortened in 2D display.

  The present invention has been made in view of the above-described circumstances. When a pixel is turned on or off for each subfield period, the gradation that can be displayed without increasing the number of subfield periods included in the frame period. Increasing the number is one of the resolution issues.

  In order to solve the above problems, a driving method of an electro-optical device according to the present invention includes M scanning lines including a first scanning line, a second scanning line, and a third scanning line, and N scanning lines. A method for driving an electro-optical device including a data line and a pixel provided corresponding to an intersection of the M scanning lines and the N data lines, the first period, and a first specific The scanning line is selected for each horizontal selection period including a period, a second period, and a second specific period, and the first scanning line is selected in the first period in one horizontal selection period. And supplying a data signal for controlling on or off the pixels in the n-th column (n is an arbitrary natural number satisfying 1 ≦ n ≦ N) corresponding to the first scanning line to the n-th data line, In the second period, the second scanning line is selected and the nth column corresponding to the second scanning line is selected. A data signal for controlling the pixel to be turned on or off is supplied to the n-th data line, and the third scanning line is selected in the first specific period and the second specific period, and the third scanning line is selected. A data signal for controlling the pixel in the n-th column corresponding to the scan line to be turned off is supplied to the data line in the n-th column, and the time length of the first specific period is the time length of the first period and the first The time length of the second specific period is shorter than the time length of the two periods, and is shorter than the time length of the first period and the time length of the second period.

  According to one aspect of the driving method of the electro-optical device according to the invention, in the first period or the second period, the data signal for controlling the pixel to be turned on or off is supplied to the data line, while In the specific period and the second specific period, a data signal for controlling the pixel to be turned off is supplied to the data line. That is, as a result of writing the data signal to the pixel in the first period or the second period, the pixel is controlled to the maximum gradation or the minimum gradation during the period until the next data signal is written. Here, the time lengths of the first specific period and the second specific period are shorter than the time length of the first period and the time length of the second period. Since the data line has a parasitic capacitance, it can be said that the data line is a capacitive load. For this reason, even when a data signal is written to a pixel in one specific period in one horizontal selection period, the gray level of the pixel is not necessarily the minimum gray level. However, the writing of the data signal in the first period and the second period is in accordance with the gradation to be displayed, while the writing of the data signal in the specific period is for controlling the gradation of the pixel to the minimum gradation. Therefore, the effect on the image quality is small. Even if a data signal sufficient to turn off the pixel in the first specific period cannot be written, the data signal to turn off the pixel is written in the second specific period, so that the gradation of the pixel is minimized. It can be close to gradation. Note that the pixel may include a liquid crystal element or a light emitting element, for example.

  In addition, an electronic apparatus according to the present invention includes the above-described electro-optical device. Such electronic devices include car navigation devices, personal computers, televisions, projection display devices, and the like.

  In one aspect of the driving method of the electro-optical device described above, the third scanning line is moved in the first specific period and the second specific period belonging to another horizontal selection period different from the one horizontal selection period. It is preferable to select and supply a data signal for controlling the n-th column pixel corresponding to the third scanning line to the n-th column data line.

  According to this aspect, since the data signal for controlling the pixel to be turned off is written also in the first specific period and the second specific period of the other horizontal selection periods, the gradation of the pixel is made closer to the minimum gradation. Can do. Thereby, the time length of a 1st specific period and a 2nd specific period can be shortened, and the time length of a 1st period and a 2nd period can be lengthened that much.

  In one aspect of the driving method of the electro-optical device described above, the first subfield period having a first time length and the second subfield period having a second time length different from the first time length are included. In a frame period for displaying one screen including a plurality of subfield periods and a plurality of erase periods, the pixels are controlled to be turned on or off for each subfield period, and the pixels are turned off in the erase periods. By controlling, the gradation to be displayed by the pixel in the frame period is controlled, and the first subfield period starts in the pixel corresponding to the first scanning line in the one horizontal selection period. And in the pixel corresponding to the second scanning line, the second subfield period starts and corresponds to the third scanning line. Preferably, the erase period is started in the pixel.

  According to this aspect, it is possible to perform subfield driving, and by selecting three scanning lines in one horizontal selection period, the pixels corresponding to the first scanning line can select the first subfield period. The second subfield period can be started in the pixel corresponding to the second scan line, and the erase period can be started in the pixel corresponding to the third scan line.

  In one aspect of the driving method of the electro-optical device described above, the frame period is divided into a plurality of block periods including a first block period and a second block period, and the first block period is divided into a predetermined number of unit periods. Dividing, dividing the second block period into the predetermined number of unit periods, and allocating the first subfield period in the first block period and the second block period, and the second subfield It is preferable that the unit period to which the period is allocated is different. According to this aspect, since the order of the first subfield period and the second subfield period differs between the first block period and the second block period, variations in combinations of subfield periods increase, and one frame period The number of gradations that can be displayed can be increased.

  Next, according to one aspect of the electro-optical device according to the invention, the M scan lines including the first scan line, the second scan line, and the third scan line, the N data lines, and the M Comprising pixels provided corresponding to the intersection of one scanning line and the N data lines, the first period, the first specific period, the second period, and the second specific A scanning line driving circuit that selects at least three scanning lines for each horizontal selection period including the period and pixels in the nth column (n is an arbitrary natural number satisfying 1 ≦ n ≦ N) are controlled to be turned on or off. A data line driving circuit for supplying a data signal to the data line of the n-th column. In one horizontal selection period, in the first period, the scanning line driving circuit selects the first scanning line, and The data line driving circuit is a data signal for controlling on / off the pixels in the nth column corresponding to the first scanning line. Is supplied to the n-th data line, and in the second period, the scanning line driving circuit selects the second scanning line, and the data line driving circuit corresponds to the second scanning line. A data signal for controlling on / off of the pixel of the eye is supplied to the data line of the nth column, and in the first specific period and the second specific period, the scanning line driving circuit supplies the third scanning line to the data line. The data line driving circuit supplies a data signal for controlling the n-th column pixel corresponding to the third scanning line to off to the n-th column data line, and the time length of the first specific period is selected. Is shorter than the time length of the first period and the time length of the second period, and the time length of the second specific period is shorter than the time length of the first period and the time length of the second period. It is characterized by that.

  According to this aspect, in the first period or the second period, the data signal for controlling the pixel to be turned on or off is supplied to the data line, while in the first specific period and the second specific period. A data signal for controlling the pixel to be turned off is supplied to the data line. That is, as a result of writing the data signal to the pixel in the first period or the second period, the pixel is controlled to the maximum gradation or the minimum gradation during the period until the next data signal is written. Here, the time lengths of the first specific period and the second specific period are shorter than the time length of the first period and the time length of the second period. Since the data line has a parasitic capacitance, it can be said that the data line is a capacitive load. For this reason, even when a data signal is written to a pixel in one specific period in one horizontal selection period, the gray level of the pixel is not necessarily the minimum gray level. However, the writing of the data signal in the first period and the second period is in accordance with the gradation to be displayed, while the writing of the data signal in the specific period is for controlling the gradation of the pixel to the minimum gradation. Therefore, the effect on the image quality is small. Even if a data signal sufficient to turn off the pixel in the first specific period cannot be written, the data signal to turn off the pixel is written in the second specific period, so that the gradation of the pixel is minimized. It can be close to gradation.

  In the electro-optical device according to the aspect of the invention described above, in the specific period belonging to another horizontal selection period different from the one horizontal selection period, the scanning line driving circuit selects the third scanning line. It is preferable that a data signal for controlling the pixel in the nth column corresponding to the third scanning line to be turned off is supplied to the data line in the nth column.

  According to this aspect, since the data signal for controlling the pixel to be turned off is written also in the first specific period and the second specific period of the other horizontal selection periods, the gradation of the pixel is made closer to the minimum gradation. Can do. Thereby, the time length of a 1st specific period and a 2nd specific period can be shortened, and the time length of a 1st period and a 2nd period can be lengthened that much.

  In one aspect of the electro-optical device according to the present invention described above, in the frame period for displaying one screen including a plurality of subfield periods and a plurality of erase periods, the pixel is turned on or off for each subfield period. And the gray level to be displayed by the pixel in the frame period is controlled by controlling the pixel to be turned off in the erase period, and the scanning line driving circuit controls the subfield period and the erase period. A shift register that sequentially shifts a start pulse designating start in synchronization with a clock signal and outputs M shift signals that are exclusively active every horizontal selection period, and a first active register in the first period. One enable pulse, a second enable pulse that is active in the second period, and the first M for selecting the m-th scanning line based on the erase pulse that is active in the fixed period and the second specific period and the m-th shift signal (m is an arbitrary natural number satisfying 1 ≦ m ≦ M). It is preferable to include a scan selection circuit that generates a second scan signal.

  According to this aspect, it is possible to perform subfield driving, and by selecting three scanning lines in one horizontal selection period, the pixels corresponding to the first scanning line can select the first subfield period. The second subfield period can be started in the pixel corresponding to the second scan line, and the erase period can be started in the pixel corresponding to the third scan line.

  Next, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention. Such electronic devices include projectors, televisions, personal computers, and the like.

1 is a block diagram of an electro-optical device according to an embodiment of the invention. FIG. It is a circuit diagram of a pixel circuit. It is explanatory drawing for demonstrating the operation | movement period of the pixel in 2D display. It is explanatory drawing for demonstrating the operation period of the pixel in 3D display. It is a block diagram which shows the structure of a scanning line drive circuit. 6 is a timing chart for explaining the operation of the scanning line driving circuit in 2D display. 6 is a timing chart for explaining the operation of the electro-optical device in 3D display. 6 is a timing chart for explaining the operation of the scanning line driving circuit in 3D display. 9 is a timing chart for explaining the operation of the electro-optical device in which the period Tx in FIG. 8 is enlarged. It is explanatory drawing for demonstrating the operation period of the pixel in 3D display which concerns on the modification of this invention. It is a perspective view of an electronic device (projection type display device). It is a perspective view of an electronic device (personal computer).

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the size and scale of each part are appropriately changed from the actual ones. Further, since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are attached thereto. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

<A. Embodiment>
FIG. 1 is a block diagram of an electro-optical device 1 according to an embodiment of the present invention. The electro-optical device 1 alternately displays a right-eye image and a left-eye image to which parallax is given in a time-division manner, thereby displaying a stereoscopic image and a 2D image. Display is possible. In the present embodiment, the electro-optical device 1 performs 3D display and 2D display by subfield driving.

The electro-optical device 1 includes an electro-optical panel 10, a control unit 50, and stereoscopic glasses 60.
The electro-optical panel 10 includes a display unit 30 in which a plurality of pixels Px are arranged, and a drive circuit 20 that drives each pixel Px. On the electro-optical panel 10, right-eye images and left-eye images are alternately displayed in a time division manner. Hereinafter, the drive circuit 20 and the control unit 50 may be collectively referred to as the control drive unit 100.

  As shown in FIG. 1, the display unit 30 is formed with M scanning lines 32 extending in the x direction and N data lines 34 extending in the y direction intersecting the x direction. (M and N are natural numbers). A plurality of pixels Px are arranged in a matrix of vertical M rows × horizontal N columns corresponding to each intersection of the scanning lines 32 and the data lines 34 in the display unit 30. In the present embodiment, the pixels Px are arranged at all of the M × N intersections formed by the M scanning lines 32 and the N data lines 34, but some of these M × N intersections. It does not matter even if it is arranged.

The drive circuit 20 is a circuit that supplies a data signal VD [n] (n = 1 to N) designating a gradation to be displayed by each pixel Px to a pixel circuit 40 provided corresponding to each pixel Px. A scanning line driving circuit 22 and a data line driving circuit 24 are provided.
The scanning line driving circuit 22 sequentially selects the scanning lines 32 by supplying the scanning signals Y [1] to Y [M] corresponding to the scanning lines 32 to the scanning lines 32. Specifically, the scanning signal Y [m] (m = 1 to M) is set to a predetermined selection potential (that is, the scanning line 32 of the mth row is selected), so that the scanning line 32 of the mth row. Is selected.
The data line driving circuit 24 supplies data signals VD [1] to VD [n] to each of the N data lines 34 in synchronization with the selection of the scanning line 32 by the scanning line driving circuit 22. The data signal VD [n] (n = 1 to N) is variably set according to the gradation specified by the input image data Din described later for each pixel Px.

FIG. 2 is a circuit diagram of the pixel circuit 40 provided corresponding to each pixel Px. As shown in FIG. 2, each pixel circuit 40 includes a liquid crystal element CL, a selection switch Sw, and a capacitor Co.
The liquid crystal element CL is an electro-optical element including a pixel electrode 41, a common electrode 42, and a liquid crystal 43 provided between the pixel electrode 41 and the common electrode 42. The transmittance (display gradation) of the liquid crystal 43 changes according to the voltage applied between the pixel electrode 41 and the common electrode 42. The common electrode 42 is set to a constant potential Vcom. The capacitor Co has one end electrically connected to the pixel electrode 41 and the other end electrically connected to a capacitor line 36 maintained at a constant voltage. The common electrode 42 is also electrically connected to the capacitor line 36.

The selection switch Sw is, for example, an N-channel transistor, and is provided between the pixel electrode 41 and the data line 34, and controls the electrical connection (conduction / insulation) between the two. Specifically, the gate of the selection switch Sw that is an N-channel transistor is electrically connected to the scanning line 32, and when the scanning signal Y [m] is set to the selection potential, the pixel circuit 40 in the m-th row. The selection switch Sw provided in is turned on. When the selection switch Sw is turned on, the data signal VD [n] is supplied from the data line 34 to the pixel circuit 40, and a voltage corresponding to the data signal VD [n] is applied to the liquid crystal element CL. The As a result, the liquid crystal element CL of the pixel circuit 40 is set to a transmittance corresponding to the data signal VD [n], and the pixel Px corresponding to the pixel circuit 40 has a gradation corresponding to the data signal VD [n]. Is displayed.
After the voltage corresponding to the data signal VD [n] is applied to the liquid crystal element CL of the pixel circuit 40, when the selection switch Sw is turned off, the data signal VD [n] is held by the capacitor Co. Therefore, each pixel Px displays a gradation corresponding to the data signal VD [n] in a period from when the selection switch Sw is turned on to when it is next turned on.

Returning to FIG. As shown in FIG. 1, the control unit 50 includes a display control circuit 51, a glasses control circuit 52, and an LUT (Look Up Table) 53.
Input image data Din is supplied to the display control circuit 51 from a host device (not shown) in synchronization with a synchronization signal.
Here, the input image data Din is data for designating a gradation to be displayed in each pixel Px. In the present embodiment, the input image data Din is digital data that defines the gradation to be displayed in each pixel Px in 256 steps (ie, 8 bits) from “0” to “255”.
The synchronization signal is a signal including, for example, a vertical synchronization signal Vsnc, a horizontal synchronization signal, and a dot clock signal.

The display control circuit 51 generates a control signal Ctr that is a signal for controlling the operation of the electro-optical panel 10 based on the synchronization signal supplied from the host device, and supplies the generated control signal Ctr to the drive circuit 20. To do. Here, the control signal Ctr is, for example, a signal including a vertical synchronization signal Vsnc, a Y input pulse signal Dyin, a Y clock signal Cly, enable signals EB1 to EB10, a dot clock signal, and the like. Details of these various signals will be described later.
The LUT 53 stores the gradation specified by the input image data Din for each pixel Px and the subfield code (SF code) Cd in association with each other. The correspondence between the gradation and the SF code Cd is different between 3D display and 2D display.
The display control circuit 51 acquires the SF code Cd corresponding to the input image data Din from the LUT 53, generates image data Dx based on the acquired SF code Cd, and then generates the generated image data Dx as the data line driving circuit 24. Supply against. In the present embodiment, the image data Dx is a digital signal, but may be an analog signal.

Based on the control signal Ctr generated by the display control circuit 51, the glasses control circuit 52 generates a glasses control signal that is a signal for controlling the operation of the stereoscopic glasses 60, and supplies this to the stereoscopic glasses 60. To supply.
The stereoscopic glasses 60 are glasses-type instruments worn by an observer when viewing a stereoscopic image displayed on the electro-optical panel 10, and include a left-eye shutter 62 and a right eye positioned in front of the left eye of the observer. And a right-eye shutter 64 positioned in front of the camera. Each of the left-eye shutter 62 and the right-eye shutter 64 is based on the spectacles control signal supplied from the spectacles control circuit 52, and is in an open state (transmission state) that transmits the irradiation light and a closed state that blocks the irradiation light ( The light shielding state). For example, a liquid crystal shutter that changes from one of the open state and the closed state to the other by changing the alignment direction of the liquid crystal according to the applied voltage may be employed as the left-eye shutter 62 and the right-eye shutter 64.

FIG. 3 is an explanatory diagram for explaining an operation period in 2D display of each pixel Px (pixel circuit 40) included in the electro-optical device 1, and FIG. 4 is a 3D display of each pixel Px included in the electro-optical device 1. It is explanatory drawing for demonstrating the operation | movement period.
As shown in FIGS. 3 and 4, the operation period of each pixel Px is defined by a frame period F. The frame period F is a period determined for each pixel Px, and is a period required for displaying one screen. More specifically, the frame period F in the 2D display shown in FIG. 3 is a period necessary for each pixel Px to display a gradation corresponding to a two-dimensional image, and the 3D display shown in FIG. In the case of the frame period F, when the electro-optical device 1 displays one stereoscopic image including one left-eye image and one right-eye image, each pixel Px has the one stereoscopic image. (I.e., the gradation corresponding to one left-eye image and the gradation corresponding to one right-eye image). For example, when the electro-optical device 1 displays 60 stereoscopic images per second, the frame period F is about 16.67 milliseconds.

  As shown in FIG. 3, the frame period F for 2D display is divided into a first control period C1 and a second control period C2. The first control period C1 is a period including a first block period B1 and a second block period B2, and a positive data signal VD [n] is written to the pixel Px. The second control period C2 is a period including a third block period B3 and a fourth block period B4, and a negative data signal VD [n] is written to the pixel Px. Here, the polarity of the data signal VD [n] means that the high potential data signal VD [n] is positive with respect to the potential Vcom of the common electrode 42, and the low potential data signal VD [n] is negative. That's it. The first to fourth block periods B1 to B4 may be collectively referred to as “block period B”.

  The 2D display block period B includes 10 subfield periods Sf1 to Sf10. In this example, the time lengths of the subfield periods Sf1 to Sf10 are different. In the subfield periods Sf1 to Sf10, the data signal VD [n] for controlling the pixel Px to be turned on or off is written to the pixel Px. Therefore, weighting is performed by changing the time lengths of the subfield periods Sf1 to Sf10. FIG. 3 shows the subfield periods Sf1 to Sf10 of the first block period B1 and the second block period B2, but the same applies to the third block period B3 and the fourth block period B4.

  As shown in FIG. 4, the frame period F for 3D display includes a display period T1 for the left-eye image (hereinafter simply referred to as “display period T1”) and a display period T2 for the right-eye image (hereinafter simply referred to as “ Referred to as “display period T2”). In this example, each of the display periods T1 and T2 includes a first block period B1, a second block period B2, a third block period B3, and a fourth block period B4. Hereinafter, the display period T1 and the display period T2 may be collectively referred to as “display period T”.

  The block period B in 3D display includes six unit periods, and includes five subfield periods Sf1 to Sf5 and an erase period E. In this example, the time length of the subfield periods Sf1 and Sf2 is Ta, the time length of the subfield periods Sf3 and Sf4 is Tb, the time length of the subfield period Sf5 is Tc, and Ta <Tb <Tc. There is a relationship. In the subfield periods Sf1 to Sf5, the data signal VD [n] for controlling the pixel Px to be turned on or off is written to the pixel Px, and in the erase period E, the data signal VD [n] for controlling the pixel Px to be turned off is written. Written.

  The display period T is divided into a first control period C1 and a second control period C2. The first control period C1 is a period including a first block period B1 and a second block period B2, and a positive data signal VD [n] is written to the pixel Px. The second control period C2 is a period including a third block period B3 and a fourth block period B4, and a negative data signal VD [n] is written to the pixel Px.

In the first control period C1 in which the positive polarity data signal VD [n] is written in the 3D display, the first block period B1 and the second block period B2 are in the order of Sf1, Sf2, Sf3, Sf4, Sf5, and E. Subfield periods Sf1 to Sf5 and an erase period E are assigned to each unit period.
On the other hand, in the second control period C2 in which the negative polarity data signal VD [n] is written in 3D display, Sf5 → Sf4 → Sf3 → Sf2 → Sf1 → E in the third block period B3 and the fourth block period B4. Subfield periods Sf1 to Sf5 and an erase period E are assigned to each unit period in order.

That is, the order of the subfield periods is different between the first block period B1 and the second block period B2, and the third block period B3 and the fourth block period B4. In this way, by changing the arrangement of the subfield periods between the positive polarity and the negative polarity, the variation of combinations of the subfield periods increases, and the number of SF codes Cd can be increased.
In the erase period E assigned to the last unit period of the block period B, control for displaying black on the pixel Px is executed. Considering the gamma characteristics of the electro-optical panel 10, it is important to improve the gradation on the low gradation side. By providing the erase period E, the display gradation can be shifted to the lower gradation side, so that the display quality can be improved.

In the 2D display, the data line driving circuit 24 performs the data signal VD [n at the timing when each of 40 unit periods (subfield periods Sf1 to Sf10) per frame period F is started for each pixel Px. In the 3D display, at the timing when each of the 24 unit periods (subfield periods Sf1 to Sf5 and erase period E) included in each display period T is started for each pixel Px, the data A signal VD [n] is supplied.
In the present embodiment, the data signal VD [n] is a signal that designates ON or OFF of the pixel Px. Specifically, when the data signal VD [n] designates ON for the pixel Px, the potential at which the pixel Px displays the maximum gradation (that is, transmission of the liquid crystal element CL included in the pixel Px). The potential at which the rate becomes the maximum value). In addition, when the data signal VD [n] is designated to be off for the pixel Px, the potential at which the pixel Px displays the minimum gradation (that is, the transmittance of the liquid crystal element CL included in the pixel Px is minimum). Value).

  The data line driving circuit 24 generates a data signal VD [n] to be supplied to each pixel Px based on the image data Dx supplied from the display control circuit 51. As described above, the display control circuit 51 acquires the SF code Cd corresponding to the input image data Din from the LUT 53, and generates the image data Dx based on the acquired SF code Cd. The LUT 53 includes a 2D table 53a for 2D display and a 3D table 53b for 3D display.

The LUT 53 includes 256 types of gradations “0” to “255” that can be specified for each pixel Px by the input image data Din, and 256 SF codes Cd corresponding to these 256 types of gradations on a one-to-one basis. (Cd [0] to Cd [255]) are associated with each other and stored in 2D display and 3D display, respectively.
Each SF code Cd stored in the 2D table 53a is a value “designating that the pixel Px is turned on for each of the 20 subfield periods S included in the first control period C1 and the second control period C2. This is 20-bit data in which either “1” or a value “0” that designates turning off the pixel Px is set. On the other hand, each SF code Cd stored in the 3D table 53a turns off the value “1” that designates turning on the pixel Px or turning off the pixel Px for each of the 20 subfield periods S included in the display period T. This is 20-bit data in which one of the values “0” for designating is set.
As a general rule, the SF code Cd is applied to each subfield period S so that the time length during which the pixel Px is turned on in the display period T becomes longer as the level of the gradation that the pixel Px should display in the display period T becomes higher. This specifies the on / off state of the pixel Px.

The display control circuit 51 refers to the LUT 53 and acquires the SF code Cd corresponding to the input image data Din. As a result, when the display control circuit 51 displays the gradation specified by the input image data Din on the pixel Px in the display period T, the display control circuit 51 performs the pixel in each of the 20 subfield periods S included in the display period T. It can be determined based on the SF code Cd whether to specify an on or off state for Px.
When the SF code Cd indicates a value “1” that specifies that the pixel Px is turned on for each subfield period S, the display control circuit 51 specifies a data signal that specifies the maximum gradation for the pixel Px. When image data Dx corresponding to VD [n] is generated and a value “0” indicating that the pixel Px is to be turned off is indicated, it corresponds to the data signal VD [n] that specifies the minimum gradation for the pixel Px. The image data Dx to be generated is generated.

  In the present embodiment, the pixel Px includes the liquid crystal element CL, and the gradation displayed by the pixel Px is controlled by controlling the transmittance of the liquid crystal element CL.

  FIG. 5 shows a block diagram of the scanning line driving circuit 22. As shown in this figure, the scanning line driving circuit 22 includes a shift register 221 and a scanning line selection circuit 222. The shift register 221 sequentially shifts the Y input pulse signal Dyin according to the Y clock signal Cly, and generates shift signals SR [1] to SR [M] that are exclusively active every horizontal selection period.

The scanning line selection circuit 222 includes a plurality of selection units U. The first selection unit U includes 20 NAND circuits 230 and 20 inverters 240. Any one of the shift signals SR [1] to SR [20] is supplied to one input terminal of each NAND circuit 230, and any one of the enable signals EB1 to EB10 is supplied to the other input terminal. Supplied. The output signal of the NAND circuit 230 is inverted by the inverter 240 and output to the scanning line 32 as a scanning signal.
FIG. 6 shows a timing chart of the scanning line driving circuit 22 in 2D display. As shown in this figure, the enable signals EB1 to EB10 have enable pulses EP1 to EP10 that become active at 10 timings obtained by dividing the half cycle of the Y clock signal Cly into 10, respectively. The ten timings are given by the definition of the address within one clock shown in FIG.

  FIG. 7A is a timing chart for explaining the relationship between the operation period of the pixel Px and the operation period of the electro-optical device 1 in 3D display. As shown in this figure, the scanning lines 32 from the first row to the M-th row are sequentially selected every horizontal selection period. In 3D display, one block period B includes five subfield periods Sf1 to Sf5 and one erase period E. For this reason, it is necessary to exclusively select six scanning lines 32 in a certain horizontal selection period.

  This means that the six scanning signals Y are exclusively activated in a certain horizontal selection period. In 3D display, the time length of the horizontal selection period is shorter than that in 2D display. Therefore, in order to secure time for writing the data signal VD [n] to the pixel Px, it is exclusively active in a certain horizontal selection period. It is necessary to limit the number of scanning signals Y.

  The erase period E is long in the block period B4 in order to limit the number of scanning signals Y that are exclusively active in the horizontal selection period. As described above, in order to secure the number of SF codes Cd while limiting the number of subfield periods, in this embodiment, the order of the subfield periods is changed between the first control period C1 and the second control period C2. ing. For this reason, it is necessary to make the erase period E of the block period B4 longer than the erase period E of the block periods B1 to B3.

If the time lengths of the erase periods E of all the block periods B1 to B4 are equal, the transition between the subfield periods Sf1 to Sf5 and the erase period E in the first to Mth rows is as shown in FIG. It will be shown. In this case, for example, at time Tc, three scanning lines 32 are selected to start the subfield periods Sf1 and Sf2 of the block period B4 and the erase period E, and further, the subfield periods Sf1 to Sf1 of the block period B1 are selected. In order to start Sf4, four scanning lines 32 need to be selected.
Therefore, in this embodiment, as shown in FIG. 7A, the erase period E of the block period B4 is lengthened. Note that the scanning line 32 is not selected in the period Tw shown in FIG.

  FIG. 8 is a timing chart showing the relationship between the enable signals EB1 to EB10 and the Y clock signal Cly in 3D display. In the 2D display, the enable signals EB1 to EB10 are generated using the 10 enable pulses EP1 to EP10. In the 3D display, the enable signals EB1 to EB10 are used using the 5 enable pulses EP1 to EP5 and the erase pulse ELP. Is generated. The enable pulses EP1 to EP5 and the erase pulse ELP are exclusively active. The erase pulse ELP is between the enable pulses EP1 and EP2, between the enable pulses EP2 and EP3, between the enable pulses EP3 and EP4, and between the enable pulses EP4 and During EP5, it becomes active between enable pulses EP5 and EP1.

  FIG. 9 shows a timing chart in which the period Tx in FIG. 8 is enlarged. The data signal VD [n] is written to the pixel Px in the first row and the nth column during the period in which the enable signal ENB1 becomes high level and becomes active. For this reason, the potential V [n] held in the pixel Px in the n-th column of the predetermined row is such that the data signal VD [n] is the pixel in the first row and n-th column in the periods Ta and Tb in which the enable pulse EP1 is active. Written to Px. As a result, in the example shown in FIG. 9, the potential V [n] held in the pixel Px in the n-th column of the predetermined row becomes the potential Vmax. Thereafter, when the erase pulse ELP becomes active, the potential Vmin is written to the pixel Px in the first row and nth column. However, since the period during which the erase pulse ELP is active is shorter than the enable pulses EP1 to EP5, one write operation is performed. Then, the potential V [n] does not become the potential Vmin, but becomes the potential Vmin by writing a plurality of times. In this example, the potential V [n] is converged to the potential Vmin by the four erase pulses ELP, but the potential V [n] is converged to the potential Vmin by the writing using the ten erase pulses ELP. do it.

  As a result, it is not necessary to assign the enable pulses EP1 to EP5 to the erase period E for displaying black, and the pulse width of the enable pulses EP1 to EP5 can be increased. As a result, the erase period E can be introduced without reducing the scanning speed of the scanning line 32, and the gradation can be greatly improved.

  For example, as shown in FIG. 7, in the first horizontal selection period of the block period B2, the first scanning line 32, the h1st scanning line 32, and the h2nd scanning line 32 are displayed. Are selected. In this case, in the first horizontal selection period Ty (one horizontal selection period) shown in FIG. 9, in the period Ta1 (first period) in which the enable pulse EP1 is active, the scanning line 32 (first first row) The scanning signal Y [1] for selecting the scanning line) becomes active. Therefore, in the period Ta1, the data signal VD [n] for controlling the pixel 40 to be turned on or off is supplied to the n-th data line 34.

  In the horizontal selection period Ty, in the period Ta2 (second period) in which the enable pulse EP2 is active, the scanning signal Y [h2] for selecting the scanning line 32 (second scanning line) in the h2nd row is active. Thus, in the period Ta1, the data signal VD [n] for controlling the pixel 40 to be turned on or off is supplied to the data line 34 in the n-th column.

  Further, in the horizontal selection period Ty, in the period Te1 (first specific period), Te2 (second specific period), Te3, Te4, and Te5 in which the erase pulse ELP is active, the scanning line 32 in the h1th row. The scanning signal Y [h1] for selecting (third scanning line) becomes active, and the data signal VD [n] for controlling the pixel 40 to be turned off is supplied to the n-th data line 34 in the periods Te1 to Te5. The

  Thereby, in the horizontal selection period Ty, a certain subfield period (first subfield period) is started in the pixel 40 corresponding to the first row scanning line 32 (first scanning line), and the h2nd row Another subfield period (second subfield period) is started in the pixel 40 (second scanning line) corresponding to the scanning line 32 of the eye, and the pixel 40 (seconding line) corresponding to the scanning line 32 of the h1th row. 3), the erase period starts.

In addition, in another horizontal selection period Tz different from the horizontal selection period Ty, in a period Te1 to Te5 in which the erase pulse ELP is active, the scanning signal Y [h1] for selecting the scanning line 32 in the h1st row is active. Thus, in the periods Te1 to Te5, the data signal VD [n] for controlling the pixel 40 to be turned off is supplied to the n-th data line 34.
Here, the time length of the periods Te1 to Te5 is shorter than the time length of the period Ta1 and shorter than the time length of the period Ta2. Further, the scanning signal Y [h2] is activated on the scanning line 32 in the h1th row in synchronization with ten erase pulses ELP over a plurality of horizontal selection periods Ty and Tz. Here, the total time length of the pulse widths of the 10 erase pulses ELP can be made longer than the time length of the pulse width of one enable pulse. On the other hand, the total time length of the pulse widths of the five erase pulses ELP belonging to one horizontal selection period Ty can be made shorter than the time length of the pulse width of one enable pulse. For this reason, the pulse width of the enable pulses EP1 to EP5 can be increased, and the data signal VD [n] for controlling the pixel 40 to be turned on or off can be reliably written to the pixel 40.

  As described above, in the present embodiment, in the 3D display, by introducing the erase period E in addition to the sub-feed periods Sf1 to Sf5, the number of scanning lines 32 to be selected in a certain horizontal selection period is limited. It was possible to change the order of the subfield periods Sf1 to Sf5 in the block period B and the order of the subfield periods Sf1 to Sf5 in the other block periods. As a result, the variation in the combination of the subfield periods Sf1 to Sf5 for controlling the pixel 40 to be turned on or off can be increased to improve the gradation. Furthermore, the data signal VD [n] for controlling the pixel 40 to be turned off is written to the pixel 40 using the erase pulse ELP that is active during part or all of the period in which the enable pulses EP1 to EP5 are inactive. It becomes possible to increase the pulse width of the enable pulses EP1 to EP5.

<B. Modification>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other.

(1) Modification 1
In the above-described embodiment, the erase period E is provided in the case of 3D display. However, the present invention is not limited to this, and in the 2D display, the erase period E may be provided as in the above-described embodiment. . In this case, even if the frame period F is shortened, it is possible to display an image without greatly reducing the gradation. For example, when displaying content such as sports, it is possible to display an image with little afterimage by shortening the frame period F.

(2) Modification 2
In the embodiment described above, the period Tw in which the scanning line is not selected is provided in the case of 3D display. However, the period may be a reset period R in which the left-eye shutter and the right-eye shutter are simultaneously closed. FIG. 10 is an explanatory diagram for explaining the operation period of the pixel Px according to the second modification. In this example, a reset period R is provided between the display period T1 and the display period T2. Since the image displayed in the display period T1 and the image displayed in the display period T2 are different, by providing the reset period R, crosstalk between the image for the left eye and the image for the right eye is prevented, and 3D The display quality of the display can be improved.

(3) Modification 3
In the embodiment and the modification described above, the pixel circuit 40 provided corresponding to the pixel Px includes the liquid crystal element CL as an example of an electro-optical element, but includes a light emitting element such as an organic light emitting diode. Also good.

<C. Application example>
The electro-optical device 1 exemplified in the above embodiments can be used in various electronic apparatuses. 11 and 12 exemplify specific forms of electronic equipment that employs the electro-optical device 1.

  FIG. 11 is a schematic diagram of a projection display device (three-plate projector) 4000 to which the electro-optical device 1 is applied. The projection display device 4000 includes three electro-optical devices 1 (1R, 1G, 1B) corresponding to different display colors (red, green, blue). The illumination optical system 4001 supplies the red component r of the light emitted from the illumination device (light source) 4002 to the electro-optical device 1R, the green component g to the electro-optical device 1G, and the blue component b to the electro-optical device 1B. To supply. Each electro-optical device 1 functions as a light modulator (light valve) that modulates each monochromatic light supplied from the illumination optical system 4001 in accordance with a display image. The projection optical system 4003 synthesizes the emitted light from each electro-optical device 1 and projects it onto the projection surface 4004. An observer visually recognizes an image projected on the projection surface 4004.

  FIG. 12 is a perspective view of a portable personal computer that employs the electro-optical device 1. The personal computer 2000 includes an electro-optical device 1 that displays various images, and a main body 2010 on which a power switch 2001 and a keyboard 2002 are installed.

  The electronic apparatus to which the electro-optical device according to the present invention is applied includes, in addition to the apparatus illustrated in FIGS. 11 and 12, a personal digital assistant (PDA), a digital still camera, a television, a video camera, Car navigation devices, in-vehicle displays (instrument panels), electronic notebooks, electronic paper, calculators, word processors, workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices with touch panels, etc. Can be mentioned.

DESCRIPTION OF SYMBOLS 1 ... Electro-optical device, 10 ... Electro-optical panel, 20 ... Drive circuit, 22 ... Scan line drive circuit, 24 ... Data line drive circuit, 30 ... Display part, 32 ... Scan line, 34 ... Data line, 40 ... Pixel circuit, 50 ... Control unit, 51 ... Display control circuit, 52 ... Glasses control circuit, 53 ... LUT, 60 ... Stereoscopic glasses, 62 ... Shutter for left eye 64 ... right eye shutter, 100 ... control drive unit, 221 ... shift register, 222 ... scanning line selection circuit, Px ... pixel, CL ... liquid crystal element.

Claims (9)

  An electro-optical panel having pixels provided corresponding to the intersections of a plurality of scanning lines and a plurality of data lines is subjected to subfield driving to display a right-eye image and a left-eye image in a first display period and a second display period. Driving method for performing 3D display alternately in time division,
  The frame period has a plurality of subfield periods having different time lengths and a plurality of erase periods,
  In the plurality of subfield periods, a data signal for controlling pixels on or off is supplied to the data line,
  In the plurality of erase periods, a data signal for controlling pixels to be off is supplied to the data line,
  Of the first display period and the second display period, immediately before the end of one display period and immediately after the start of the other display period, the subfield period becomes a subfield period having a short time length.
  An electro-optical panel driving method, wherein among the plurality of erase periods, an erase period provided between the subfield periods having a short time length has a longer time length than other erase periods.   Each of the first display period and the second display period includes a first control period in which a positive data signal is written to the pixel, and a second control period in which a negative data signal is written to the pixel.
  2. The method of driving an electro-optical panel according to claim 1, wherein the order of subfield periods is different between the first control period and the second control period.   The first control period and the second control period are composed of a plurality of block periods,
  The block period includes a plurality of subfield periods followed by an erase period.
  The subfield periods of the one display period are in the order of increasing, the subfield periods of the other display period are in the order of decreasing,
  3. The method of driving an electro-optical panel according to claim 2, wherein the erase period in the last block period of the one display period is longer than the other erase period.   4. The electro-optical panel according to claim 1, wherein the 3D display and a 2D display having a subfield period larger than the 3D display and no erase period are switchable. 5. Driving method.   An electro-optical panel including pixels provided corresponding to intersections of a plurality of scanning lines and a plurality of data lines, stereoscopic glasses, and a control unit. An electro-optical device that performs 3D display for alternately displaying images for use in a time division in a first display period and a second display period,
  The electro-optical panel is controlled by a control signal from the control unit.
  The frame period has a plurality of subfield periods having different time lengths and a plurality of erase periods,
  In the plurality of subfield periods, a data signal for controlling the pixels to be turned on or off is supplied to the n-th data line,
  In the plurality of erase periods, a data signal for controlling the pixel to be turned off is supplied to the data line of the nth column,
  Of the first display period and the second display period, immediately before the end of one display period and immediately after the start of the other display period, the subfield period becomes a subfield period having a short time length.
  Of the plurality of erase periods, the erase period provided between the subfield periods having a short time length is longer than the other erase periods.
An electro-optical device.   Each of the first display period and the second display period includes a first control period in which a positive data signal is written to the pixel, and a second control period in which a negative data signal is written to the pixel.
  The electro-optical device according to claim 5, wherein the order of subfields is different between the first control period and the second control period.   The first control period and the second control period are composed of a plurality of block periods,
  The block period includes a plurality of subfield periods followed by an erase period.
  The subfield periods of the one display period are in the order of increasing, the subfield periods of the other display period are in the order of decreasing,
  The electro-optical device according to claim 6, wherein the erase period in the last block period of the one display period is longer than the other erase period.   The electro-optic according to any one of claims 5 to 7, wherein the 3D display and the 2D display having a subfield period larger than the 3D display and having no erase period are switchable. apparatus. An electronic device including an electro-optical device according to any one of claims 5 to 8.

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