JP2008070885A - Method and device for driving electro-optic element, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid different levels of gray scale resulting from irregularity of a relation in terms of position among selected sub-fields. <P>SOLUTION: The pixel driving method according to this invention includes: a selecting step of sequentially selecting, according to gray scale data, a plurality of first sub-field periods continuous with respect to one another and a plurality of second sub-field periods continuous with respect to one another and following consecutively the plurality of first sub-field periods in a direction moving away from a boundary of the plurality of first sub-field periods and the plurality of second sub-field periods, which is given as the origin; and a driving step of switching ON the pixels for the selected sub-field periods. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pixel driving method, a driving apparatus, and an electronic apparatus for driving a pixel which is an electro-optical element using pulse width modulation.

  Conventionally, a pixel driving method is used in which a plurality of pixels arranged in a matrix are driven using a scanning signal for selecting the pixel and a data signal for defining a gradation to be displayed by the pixel. It has been. Among the pixel driving methods, in order to improve the image quality of a display image, the data signal is transmitted in each of a plurality of periods (hereinafter referred to as “subfield”) provided in one frame. Sub-field driving in which application is performed for all pixels has been proposed.

  According to the subfield driving, in each subfield, a voltage (for example, high pulse) for representing each pixel as on (for example, black) or a voltage for representing off (for example, white) as the data signal (for example, white). In this way, each pixel is subjected to pulse width modulation by the data signal within one frame, and as a result, for example, one gradation of 64 gradations is applied to the pixel. Can be displayed.

However, when driving with N subfields in the conventional ^2N gray scale, the subfield to which the ON voltage is to be applied has no regularity among the plurality of subfields included in the frame. For example, there is a problem that different gradations are displayed due to the irregularity of the positional relationship between the selected subfields even though the same gradation should be displayed originally. was there.

Further, in the case of driving with (2 ^N −1) subfields with 2 ^N gradations, the number of subfields is large, and the number of times of writing a voltage to a pixel in one frame period is increased, resulting in an increase in power consumption.
Furthermore, since the number of gradations is increased, that is, the length of each subfield has to be shortened as the number of gradations is increased, the application of the data signal must be performed under time constraints. In addition, there is a problem that it is difficult to control the application of the data signal with high accuracy.

  In order to solve the above problem, an object of the present invention is to provide a pixel driving method, a driving apparatus, and an electronic apparatus that can avoid a difference in gradation caused by irregularly selected subfield positions. There is.

  The electro-optic element driving method according to the present invention includes turning on the electro-optic element during a period corresponding to gradation data that defines gradation to be displayed by the electro-optic element throughout a frame period. An electro-optical element driving method for displaying the gradation on the optical element, wherein a plurality of mutually continuous first subfield periods used for securing a period corresponding to the gradation data, and the plurality of the plurality of sub-field periods A plurality of consecutive first subfield periods, each of which is substantially equivalent to the length of the total period of the plurality of first subfield periods and one first subfield period. Two subfield periods, a first subfield period and a second subfield period positioned in contact with boundaries between the plurality of first subfield periods and the plurality of second subfield periods A selection step of sequentially selecting according to the grayscale data in the direction of a first subfield period and a second subfield period that are located farthest from the boundary from the bfield period, and during the selected subfield period, And a driving step of turning on the electro-optic element.

  In another driving method of the electro-optical element according to the present invention, the electro-optical element is turned on during a period corresponding to gradation data defining a gradation to be displayed by the electro-optical element through a plurality of frame periods. The electro-optic element driving method for causing the electro-optic element to display the gradation, and for specifying a period corresponding to the gradation data included in each frame period constituting the plurality of frame periods A plurality of first subfield periods that are continuous with each other, and a plurality of first subfield periods that are consecutive in the plurality of first subfield periods and are included in the plurality of frame periods, respectively. A plurality of second subfield periods that are continuous with each other and have a length equal to or longer than the total period of each of the plurality of first subfields for each frame period. And a first subfield period and a second subfield period that are located farthest from the boundary from a first subfield period and a second subfield period that are located between and between the plurality of second subfield periods. A selection step of sequentially selecting according to the gradation data in a direction of a subfield period, and a driving step of turning on the electro-optic element during the selected subfield period for each frame period. It is characterized by.

  Another electro-optical element driving method according to the present invention is a driving method of an electro-optical element that causes the electro-optical element to display a gradation in units of a frame period, and is timed with respect to a reference point existing in the frame period. In particular, two or more first subfield periods that are adjacent to each other on either the front side or the rear side and that turn on or off the electro-optic element are subordinate to the data that defines the gradation. In order from the reference point toward the one side in accordance with the value indicated by the bit, it exists on the other side of the reference point in time either forward or backward and adjacent to each other , One or more second subfield periods for turning on or off the electro-optic element, wherein one period is a sum of the plurality of first subfield periods A selection step of sequentially selecting a second subfield period set longer than the second subfield period from the reference point toward the other side in accordance with a value indicated by an upper bit excluding the lower bit in the data; And a driving step of continuously turning on (or turning off) the electro-optic element during the selected first and second subfield periods.

  The electro-optic element driving apparatus according to the present invention turns on the electro-optic element by turning on the electro-optic element during a period corresponding to gradation data that defines gradation to be displayed by the electro-optic element throughout the frame period. An electro-optical element driving apparatus for displaying the gradation on the optical element, wherein a plurality of mutually continuous first subfield periods used for specifying a period corresponding to the gradation data, A plurality of consecutive first subfield periods, each of which is substantially equivalent to the length of the total period of the plurality of first subfield periods and one first subfield period. Two subfield periods, a first subfield period and a second subfield period positioned in contact with boundaries between the plurality of first subfield periods and the plurality of second subfield periods A selection circuit that selects according to the grayscale data in a direction of a first subfield period and a second subfield period that are located farthest from the boundary from the bfield period; and during the selected subfield period, And a driving circuit for turning on the electro-optic element.

  In another electro-optical element driving apparatus according to the present invention, the electro-optical element is turned on during a period corresponding to gradation data that defines gradations to be displayed through the plurality of frame periods. The electro-optic element driving apparatus for displaying the gradation on the electro-optic element, wherein a plurality of mutually continuous multiples used for specifying a period corresponding to the gradation data included in each frame period The first subfield period and the plurality of first subfield periods, each of which is longer than the total period of all the first subfield periods included in the plurality of frame periods. A plurality of second subfield periods that are continuous with each other, and each of the plurality of first subfield periods and the plurality of second subfield periods for each frame period. Select according to the grayscale data in the direction of the first subfield period and the second subfield period located farthest from the boundary from the first subfield period and the second subfield period located in contact with the boundary And a driving circuit that turns on the electro-optic element during the selected subfield period for each frame period.

  An electro-optical element driving apparatus according to the present invention is an electro-optical element driving apparatus that displays a gray scale on an electro-optical element in units of a frame period, and is temporally related to a reference point existing in the frame period. Two or more first subfield periods that are adjacent to each other on either the front side or the rear side and that turn on or off the electro-optic element are represented by lower bits of the data defining the gradation. Selecting sequentially from the reference point toward the one side according to the indicated value, and existing or adjacent to each other on either the front side or the back side in time with respect to the reference point, One or more second subfield periods for turning on or off the electro-optic element, wherein one period is a total period of the plurality of first subfield periods A selection circuit that sequentially selects a second subfield period that is set to be longer from the reference point toward the other side according to a value indicated by upper bits excluding the lower bits of the data; And a driving circuit for continuously turning on (or turning off) the electro-optic element during the selected first and second subfield periods.

  An electronic apparatus according to the present invention includes a plurality of electro-optical elements arranged in a matrix, and includes a display device for displaying an image related to the electronic apparatus and any one of the electro-optical element driving devices. It is characterized by.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
An electro-optical device using a subfield driving method which is a pixel driving method according to the present invention will be described.
FIG. 1 shows the configuration of the electro-optical device according to the first embodiment. The electro-optical device includes a plurality of pixels arranged in a matrix between the element substrate and the counter substrate, and simultaneously selects a predetermined number of pixels arranged in the row direction (X) in one frame, that is, one frame period. Are sequentially performed in the vertical direction, that is, line-sequentially, and a signal for defining a gradation, that is, 0 or ± V, is applied to the pixel to display the gradation on each pixel. More specifically, for example, the electro-optical device selects a predetermined number of pixels arranged in one row for each subfield of a plurality of subfields constituting one frame. Depending on which subfield the voltage is applied to the pixel, pulse width modulation is performed on the pixel within one frame. As a result, the effective voltage value applied to the pixel can be changed, and gradation can be displayed on the pixel during one frame.
Hereinafter, applying ± V is referred to as “on”, and applying 0 is referred to as “off”. Since the liquid crystal requires AC driving, + V application and −V application are substantially synonymous from the viewpoint of gradation.

  FIG. 10 shows subfields. As shown in FIG. 10, one frame (1F) is composed of subfields SF1 to SF7. The weights of the lengths of the subfields SF1 to SF3 are set small, while the weights of the lengths of the subfields SF5 to SF7 are set large. For example, assuming that gradation data supplied to the electro-optical device and defining gradations to be displayed by pixels defines 16 gradations by 4 bits, the lengths of the subfields SF1 to SF3 are “1”. On the other hand, the length of the subfields SF5 to SF7 corresponds to “4” gradation. That is, the lengths of the subfields SF5 to SF7 substantially correspond to the total length of the three subfields SF1 to SF3 and the length of one of these subfields. In order to provide the threshold voltage Vth related to driving of the liquid crystal, the subfield SF4 provided between the subfields SF1 to SF3 and the subfields SF5 to SF7 is always turned on regardless of the gradation.

  The on / off states of the subfields SF5 to SF7 (pixels in the subfields SF5 to SF7) are determined by the upper 2 bits of the 4-bit gradation data. In other words, the subfields SF5 to SF7 are sequentially selected along the direction from the subfield SF5 to the subfield SF7 according to the upper 2 bits. For example, when the upper 2 bits are “00”, all of the subfields SF5 to SF7 are turned off, when “01”, only the subfield SF5 is turned on, and when “10”, the subfield is turned on. SF5 and SF6 are turned on. When “11”, all of the subfields SF5 to SF7 are turned on.

  The on / off states of the subfields SF1 to SF3 are determined by the lower 2 bits of the 4-bit gradation data. In other words, the subfields SF1 to SF3 are sequentially selected along the direction from the subfield SF3 to the subfield SF1 according to the lower 2 bits. For example, when the lower 2 bits are “00”, all of the subfields SF1 to SF3 are turned off, when “01”, only the subfield SF3 is turned on, and when “10”, the subfield is turned on. SF2 and SF3 are turned on. When “11”, all of the subfields SF1 to SF3 are turned on.

  The on / off normal state of the subfields SF5 to SF7 and the subfields SF1 to SF3 will be described in more detail. For example, when the gradation data is “1001” defining the “9” gradation, as shown in FIG. In addition, the subfields SF5 and SF6 are turned on, and the subfield SF3 is turned on. Further, for example, when the gradation data is “1110” defining the “14” gradation, all of the subfields SF5 to SF7 are turned on and the subfields SF2 and SF3 are set as shown in FIG. Turn on.

Here, N-bit gradation data that defines gradations having a gradation number of 2 to the Nth power (N is an integer equal to or greater than 2) is represented by upper M bits (M is a positive integer smaller than N) and lower ( NM) bits, the number of first subfields corresponding to the lower (NM) bits and the second subfields corresponding to the upper M bits. ^Assuming that the numbers of (2 ^N−M −1) and (2 ^M −1) are, respectively, and the weight of the first subfield is α, the second sub weighting of the field will α2 ^N-M.

  As described above, a plurality of mutually continuous subfields (SF5 to SF7) and a plurality of mutually continuous subfields (SF1 to SF3) are substantially adjacent to each other in accordance with the gradation data. From the boundary (reference point) between the subfields SF5 and SF3 to be performed, in other words, from the subfield SF4 (rear end) to the subfield SF1 or the subfield SF7. That is, the subfields SF1 to SF3 and the subfields SF5 to SF7 are sequentially selected from the center of the frame period to the outside. Therefore, the subfield to be turned on can be continuously selected regardless of the value of the grayscale data, thereby avoiding the occurrence of a grayscale defect due to the discontinuity of the subfield. It becomes possible.

  In addition, by providing a subfield SF4 that should always be on at the boundary between the upper bit subfield and the lower bit subfield, the voltage effective value corresponding to the characteristics of the liquid crystal can be obtained while maintaining the above continuity. Since it can be applied to the liquid crystal, gradation control can be performed accurately.

  Returning to FIG. 1, the electro-optical device includes a display unit 101a, an oscillation circuit 150, a timing signal generation circuit 200, a data conversion circuit 300, a scanning line driving circuit 130, a data line, as shown in FIG. Drive circuit 140.

  In the display unit 101a, the plurality of pixels 110 are arranged in m rows × n columns, and scanning lines 112 for selecting the plurality of pixels 110 are formed extending in the X (row) direction, On the other hand, a data line 114 for supplying a data signal defining the gradation to the plurality of pixels 110 is formed extending in the Y (column) direction.

  The timing signal generation circuit 200 is supplied from a vertical synchronization signal Vs, a horizontal synchronization signal Hs and a dot clock signal DCLK of input gradation data D0 to D3 supplied from a host device (not shown), and an oscillation circuit 150. Based on the read timing basic clock RCLK, the signals LCOM, FR, DY, CLY, LP, and CLX as shown in FIG. 1 are generated.

  The drive signal LCOM is a constant potential (zero potential) applied to the counter electrode of the counter substrate in order to drive the plurality of pixels 110. The AC signal FR indicates the timing at which the polarity of the voltage applied to the liquid crystal is inverted every frame. The start pulse DY indicates the position of each subfield SF1 to SF7. The clock signal CLY is used for defining a horizontal scanning period on the scanning side (Y side). The latch pulse LP defines a horizontal scanning period (1H). The clock signal CLX is a dot clock signal for display.

  The data conversion circuit 300 is supplied with gradation data D0 to D3 defining 16 gradations with 4 bits. Here, for example, D3 is the most significant bit, while D0 is the least significant bit. The data conversion circuit 300 generates a data signal Ds based on the gradation data D0 to D3, and outputs the data signal Ds to the data line driving circuit 140.

  The scanning line driving circuit 130 applies scanning signals G1, G2, G3,..., Gm to the m scanning lines 112 included in the display unit 101a based on the signals DY and CLY output from the timing signal generation circuit 200. And each of the m scanning lines 112 is selected a plurality of times during the horizontal scanning period 1H, and more specifically, one frame is composed of seven subfields shown in FIG. If there is, each scanning line 112 is selected seven times within one frame. The data line driving circuit 140 outputs the signals FR, LP, and CLX output from the timing signal generation circuit 200 and the data conversion circuit 300 to the pixels 110 for one row related to the selected scanning line 112. Based on the data signal Ds, the data signals d 1, d 2, d 3,..., Dn are supplied via n data lines 114, respectively.

  FIG. 2A shows a configuration of a pixel provided in the display portion. As shown in the figure, the gate, source, and drain of a thin film transistor (TFT) 116 are connected to the scanning line 112, the data line 114, and the pixel electrode 118, respectively, and between the pixel electrode 118 and the counter electrode 108. A liquid crystal 105 as an electro-optic material is sandwiched between the two. A storage capacitor 119 for holding charges is formed between the pixel electrode 118 and the counter electrode 108.

  In order to reduce the offset voltage between the voltage applied to the pixel electrode 118 and the voltage applied to the data line 114, the pixel shown in FIG. 2 (b) is used instead of the pixel having the configuration shown in FIG. 2 (a). A pixel having a configuration in which a P-channel transistor and an N-channel transistor are combined in a complementary manner is desirable. As shown in FIG. 2A, when one channel type transistor is used, an offset voltage is required.

  3A and 3B show the structure of the electro-optical device. The electro-optical device 100 includes, for example, a sealing material 104, a light shielding film 106, a deflecting plate, an alignment film, and a color filter in addition to the components shown in FIG.

FIG. 4 shows the configuration of the data line driving circuit. As shown in FIG. 4, the data line driving circuit 140 shown in FIG. 1 includes an X shift register 1402, a first latch circuit 1404, a second latch circuit 1406, and a potential selection circuit 1408. ing.
The X shift register 1402 uses the latch pulse LP supplied from the timing signal generation circuit 200 as a latch signal S1, S2, S3,..., Sn as a first latch in accordance with the clock signal CLX supplied from the timing signal generation circuit 200. This is sequentially supplied to the circuit 1404.

  The first latch circuit 1404 sequentially latches the data signal Ds output from the data conversion circuit 300 at the fall of the latch signals S1, S2, S3,. The second latch circuit 1406 latches the data signal Ds latched by the first latch circuit 1404 at the falling edge of the latch pulse LP and transfers the data signal Ds to the potential selection circuit 1408.

  The potential selection circuit 1408 converts the latched data signal Ds into data signals d1, d2, d3,... Dn based on the alternating signal FR output from the timing signal generation circuit 200, and applies the data signal to the data line 114. . That is, when the alternating signal FR is at the L level, the H level of the data signals d1, d2, d3,..., Dn is converted to + V1, while when the alternating signal FR is at the H level, the data signal d1. , D2, d3,... Dn are converted to -V1. Regardless of whether the alternating signal FR is L or H, the L level of the data signals d1, d2, d3,.

  FIG. 5 shows the configuration of the start pulse generating circuit, and FIG. 6 is a time chart showing the operation of the start pulse generating circuit. The start pulse generation circuit 210 is provided in the timing signal generation circuit 200 shown in FIG. 1, and generates a start pulse DY.

As shown in FIG. 5, the start pulse generation circuit 210 includes a counter 211, a comparator 212, a multiplexer 213, a ring counter 214, a D flip-flop 215, and an OR circuit 216.
The counter 211 counts the line clock signal LCLK synchronized with the clock signal CLY, and the count value is reset by the output signal of the OR circuit 216.

The ring counter 214 counts the number of start pulses DY, and the multiplexer 213 selects and outputs count data Dc1, Dc2,..., Dc7 indicating the times of the subfields SF1 to SF7 based on the count result S214 of the ring counter 214. To do.
The comparator 212 compares the count value S211 of the counter 211 with the output data value S213 of the multiplexer 213, and outputs a match signal S212 that is at the H level when they match. The comparator 212 outputs a coincidence signal S212 when the count value S211 of the counter 211 reaches the subfield break. Since the coincidence signal is fed back to the reset terminal of the counter 211 via the OR circuit 216, the counter 211 starts counting again from the subfield separation.

  The D flip-flop 215 latches the output signal of the OR circuit 216 with the line clock signal LCLK, and generates a start pulse DY. One input terminal of the OR circuit 216 is supplied with a reset signal RESET that becomes H level only for one period of the line clock signal LCLK at the start of the frame. Thereby, the count value of the counter 211 is reset to the start time of the frame.

  When the coincidence signal S212 rises, first, the start pulse DY rises at the rising timing of the line clock signal LCLK. On the other hand, since the count value S211 and the output data value S213 do not coincide with each other due to the rise of the line clock signal LCLK, the coincidence signal S212 becomes L level. Therefore, when the line clock signal LCLK rises next time, the coincidence signal S212 at the L level is latched by the D flip-flop 215, so that the start pulse DY becomes the L level. In this way, the start pulse DY is output at the beginning of each subfield.

  FIG. 7 shows the configuration of the data conversion circuit. The data conversion circuit 300 shown in FIG. 1 includes a write address control unit 310, a decoder 312, a plurality of memory blocks 321 to 327, a display address control unit 330, and an OR circuit 332. When the gradation data D0 to D3 are input, the decoder 312 receives the gradation data D0 to D3 from the subfield data SD1 which is bit data corresponding to the on / off states of the subfields SF1 to SF3 and SF5 to SF7. Convert to ~ SD3, SD5 ~ SD7. The memory blocks 321 to 327 are provided for storing subfield data SD1 to SD3 and SD5 to SD7, respectively, and m × n bits corresponding to the display area (m rows × n columns) of the element substrate 101. Memory space. The memory blocks 321 to 327 execute write and read operations asynchronously and independently.

  The write address control unit 310 supplies the write enable signal WE and the write address WAD to each memory block in synchronization with the vertical synchronization signal Vs, the horizontal synchronization signal Hs, and the dot clock signal DCLK. That is, the write address control unit 310 counts up the dot clock signal DCLK, outputs the count result as the write address WAD, and outputs the write enable signal WE every time the value of the write address WAD is determined. The count result of the write address control unit 310 is reset every time the vertical synchronization signal Vs is input. As a result, each memory block 321 to 327 is supplied with the write address WAD for sequentially accessing the m × n-bit memory space, and the subfield data SD1 to SD3 and SD5 to SD7 are displayed at the display positions in the corresponding memory block. Are sequentially stored at addresses corresponding to

  The display address controller 330 outputs an address signal RAD for accessing the bit data of the corresponding display row when each of the subfield periods is started. The address signal RAD is incremented “n−1” times in accordance with the number of display columns in synchronization with the clock signal CLX. As a result, an address signal RAD for sequentially accessing the bits in the first column to the n-th column for the corresponding display row is output.

  The read signals RD1 to RD3 and RD5 to 7 are always enabled during the corresponding subfields SF1 to SF3 and SF5 to SF7, respectively, and are turned off during the other subfield periods. As a result, in each of the subfields SF1 to SF3 and SF5 to SF7, only one corresponding memory block can be read, and the other memory blocks are read prohibited. Thereby, when the subfield SF1 is started, the m-row × n-column subfield data SD1 is sequentially read from the memory block 321.

  Similarly, in the subfields SF2 and SF3, the memory blocks 322 and 323 are accessed, and the subfield data SD2 and SD3 of m rows × n columns are sequentially read out. Next, in the subfield SF4, the ON signal S_on is held at the H level. Note that the ON signal S_on is held at the L level in a period other than the subfield SF4. Next, also in the subfields SF5 to SF7, the memory blocks 325 to 327 are similarly accessed, and the subfield data SD5 to SD7 of m rows × n columns are sequentially read out. The OR circuit 332 outputs the logical sum of the subfield data SD1 to SD3, SD5 to SD7 and the ON signal S_on as the data signal Ds.

  FIG. 8 shows a truth table used by the decoder. The truth table used by the decoder 312 includes gradation data and 1 or 0 in the subfield data (SD1 to SD3, SD5 to SD7) that defines on / off of the subfields SF1 to SF3 and SF5 to SF7. The correspondence relationship is shown. For example, to represent “5” gradation (0101), since the subfield data SD3 and SD5 are 1, the subfields SF3 and SF5 are turned on.

  FIG. 9 shows a waveform of a signal according to the first embodiment. When the start pulse DY is supplied in one frame (1F) in which the AC signal FR becomes L level, the scanning signals G1, G2, G3,..., Gm are transferred by the scanning line driving circuit 130 according to the clock signal CLY. The data are sequentially output exclusively during the period (t). The period (t) is set to a period shorter than the shortest subfield SF1.

  The scanning signals G1, G2, G3,..., Gm each have a pulse width corresponding to a half cycle of the clock signal CLY, and the scanning signal G1 corresponding to the first scanning line 112 counted from the top is a start signal. After the pulse DY is supplied, the clock signal CLY rises for the first time and is output after being delayed by at least a half cycle of the clock signal CLY. Therefore, one shot (G0) of the latch pulse LP is supplied to the data line driving circuit 140 after the start pulse DY is supplied and before the scanning signal G1 is output.

  First, when one shot (G0) of the latch pulse LP is supplied to the data line driving circuit 140, the latch signals S1, S2, S3,..., Sn are transferred by the transfer according to the clock signal CLX in the data line driving circuit 140. Are sequentially output exclusively during the horizontal scanning period (1H). Note that each of the latch signals S1, S2, S3,..., Sn has a pulse width corresponding to a half cycle of the clock signal CLX.

  The first latch circuit 1404 in FIG. 4 supplies the pixel 110 corresponding to the intersection of the first scanning line 112 counted from the top and the first data line 114 counted from the left at the falling edge of the latch signal S1. The data signal Ds is latched, and then, at the falling edge of the latch signal S2, to the pixel 110 corresponding to the intersection of the first scanning line 112 counted from the top and the second data line 114 counted from the left. Thereafter, similarly, the data signal Ds to the pixel 110 corresponding to the intersection of the first scanning line 112 counted from the top and the nth data line 114 counted from the left is similarly latched. To do.

  Thus, first, the data signal Ds for one row corresponding to the intersection with the first scanning line 112 from the top in FIG. 1 is latched dot-sequentially by the first latch circuit 1404. Note that the data conversion circuit 300 converts the grayscale data D0 to D3 of each pixel into a data signal Ds and outputs the data in accordance with the latch timing of the first latch circuit 1404.

  Next, when the clock signal CLY falls and the scanning signal G1 is output, the pixel corresponding to the intersection with the scanning line 112 is selected as a result of selecting the first scanning line 112 counted from the top in FIG. All 110 transistors 116 are turned on. On the other hand, the latch pulse LP is output at the falling edge of the clock signal CLY. At the falling timing of the latch pulse LP, the second latch circuit 1406 receives the data signal Ds latched dot-sequentially by the first latch circuit 1404 via the potential selection circuit 1408. Data signals d1, d2, d3,..., Dn are simultaneously supplied to each of the lines 114. Therefore, data signals d1, d2, d3,..., Dn are simultaneously written in the pixels 110 in the first row counted from the top.

  In parallel with this writing, the data signal Ds for one row corresponding to the intersection with the second scanning line 112 from the top in FIG. 1 is latched dot-sequentially by the first latch circuit 1404. Thereafter, the same operation is repeated until the scanning signal Gm corresponding to the mth scanning line 112 is output. That is, in one horizontal scanning period (1H) in which a certain scanning signal Gi (i is an integer satisfying 1 <i <m) is output, data for one row of the pixels 110 corresponding to the i-th scanning line 112. The writing of the signals d1, d2, d3,... Dn and the dot sequential latching of the data signal Ds for one row of the pixels 110 corresponding to the (i + 1) th scanning line 112 are performed in parallel. Note that the data signal written to the pixel 110 is held until writing in the next subfield SF2.

  Thereafter, the same operation is repeated every time the start pulse DY that defines the start of the subfield is supplied. Furthermore, even when the AC signal FR is inverted to H level after one frame has elapsed, the same operation is repeated in each subfield.

[Application of the first embodiment]
In the first embodiment described above, the data signal of the voltage + V1 or −V1 instructing ON at the start of each subfield is applied to the pixel electrode 118 by turning on the transistor 116 (on-pixel writing). In fact, the voltage of the pixel electrode 118 does not immediately become the voltage of the data signal because of a kind of capacitance due to the liquid crystal 105 sandwiched between the pixel electrode 118 and the counter electrode 108. In addition, the ON period of the transistor 116 in each sub-field is extremely short compared to the normal driving in which one vertical scan is performed in one frame. For this reason, there is a high possibility that the voltage at the pixel electrode 118 of the pixel to be turned on does not reach + V1 or −V1 in one writing operation. In other words, it is assumed that the voltage of the pixel electrode 118 approaches + V1 or −V1 as the number of times of on-pixel writing in one frame increases.
For this reason, the gradation of the pixel should ideally depend only on the total duration of the subfield that is turned on in one frame, but in practice it also depends on the number of on-pixel writes per frame. The tendency to do is strong.

However, in the first embodiment, the number of times of on-pixel writing in one frame is represented by gradations 0, 1, 2, 3 as shown by vertical bold lines in the start period of each subfield in FIG. Then, it is 1 time, 2 times, 3 times, and 4 times, respectively, and increases once in order according to the gradation, whereas it is twice in gradation 4 that is one level higher than gradation 3. On the contrary, it starts to decrease twice, and thereafter, in gradations 5, 6, and 7, it increases once again in order according to the gradation. Similarly, the gradation 7 is 5 times, the gradation 8 is 3 times, the gradation 11 is 6 times, and the gradation 12 is 4 times. End up.
That is, in the first embodiment, the number of times of on-pixel writing per frame does not increase uniformly according to the gradation.

  For this reason, in the first embodiment, the gradation designated for the pixel (indicated gradation) and the gradation (transmittance or reflectance) by the actual pixel are shown in FIG. As described above, there may be a stepped shape having a portion that is partially flat. Specifically, a phenomenon occurs in which there is almost no difference in transmittance or reflectance between the indication gradations 3 and 4. A similar phenomenon occurs between the instruction gradations 7 and 8 and the instruction gradations 11 and 12. Such a phenomenon causes a difference between the instructed gradation and the actual gradation, thereby degrading gradation reproduction characteristics as a display device.

In order to prevent such deterioration in gradation reproduction characteristics, in this application example, the setting of the sub-field that defines the on / off period of each pixel is improved as follows.
That is, when the gradation data is divided into upper bits and lower bits, the grayscale data has a period length corresponding to the weight of the least significant bit of the upper bits and a number corresponding to the maximum value that can be expressed by the upper bits. The two subfields are divided into two or more, and the divided subfields are improved so as to execute the write operation with the same contents.

  When such an application example is applied to the first embodiment in which 4-bit grayscale data is divided into lower 2 bits and upper 2 bits, as shown in FIG. 11, the period of subfields SF1 to SF3 The subfield SF5 having a period length of “4” when the length is “1” is divided into two subfields SF5a and SF5b having a period length of “1” and “3”, for example, and the divided subfields Then, the write operation with the same content is executed. Similarly, each of subfields SF6 and SF7 is divided into subfields SF6a and SF6b and SF7a and SF7b, and the same sub-field writing operation is executed in the divided subfields.

When subfields are set in this way, the number of times of on-pixel writing in one frame is, for example, three for gradation 4 that is one level higher than gradation 3, and only one decrease is required. Similarly, the gradation 7 is 6 times, the gradation 8 is 5 times, and the gradation 11 is 8 times, whereas the gradation 12 is 7 times, each of which is 1 time. It will fit in the decrease.
Therefore, in this application example, the dependence of the number of writings on the actual gradation (the actual gradation depends not only on the total period of the subfields turned on in one frame but also on the number of on-pixel writings. Can be reduced.
As a result, as shown in FIG. 13B, the designated gradation and the gradation based on the actual pixel eliminate the partially flat portion, thereby preventing the gradation reproduction characteristics from being deteriorated. It becomes possible.

Here, the division of the subfield is easily achieved by configuring the start pulse generation circuit 210 as shown in FIG. 12 and outputting the start pulse DY described above at the start of the divided subfield period. Is done.
That is, in the multiplexer 213, instead of the count data Dc5, Dc6, and Dc7 of FIG. 5, the count data DC5a, Dc5b, Dc6a, Dc6b, Dc7a, DC7b is supplied, and the comparator 212 compares the count value S211 of the counter 211 with the output data value S213 of the multiplexer 213, and outputs a match signal S212 that is at the H level when they match. .
In addition, since the subfields SF5a and SF5b may be supplied with the same data signal Ds as that of the subfield SF5 before division, the display address control unit 330 applies twice to the memory block 325 over the subfields SF5a and SF5b. The address signal RAD may be output. Similarly, the display address control unit 330 may output the address signal RAD twice to the memory block 326 over the subfields SF6a and SF6b and twice to the memory block 327 over the subfields SF7a and SF7b.

Note that each of the second subfield periods SF5, SF6, and SF7 corresponding to the weighting represented by the upper 2 bits in the gradation data may be divided into three, for example, instead of dividing into two. Further, instead of dividing the second subfield period uniformly into two, for example, the second subfield is divided so that a certain second subfield period is divided into two and another subfield period is divided into three. The number of divisions may be different between periods.
When the number of divisions differs between the second subfield periods, the number of subfields corresponding to a certain bit among the upper bits is divided into subfields corresponding to lower bits. It is desirable not to set it larger than the number. In other words, the number of divisions of the second subfield may be set so as to increase as it is closer to the boundary (reference point) with the first subfield (that is, as the corresponding bit weight is smaller). desirable.

  For example, in the application example described above, with respect to the number of divisions of the subfields SF5, SF6, and SF7, as illustrated in FIG. Here, in FIG. 14, when the period length of subfields SF1 to SF3 is set to “1”, subfield SF5 having a period length of “4” has periods of “1”, “1”, and “2”, respectively. It is divided into three subfields SF5a, SF5b and SF5c having a length. The subfields SF6 and SF7 are similarly divided into three. In this way, the division into three is possible by changing the count data supplied to the multiplexer 213 in the start pulse generation circuit 210 and controlling the access in the display address control unit 330 as described in the application example described above. It is.

  Thus, the reason why the number of divisions of the second subfield is set so as to increase as it approaches the boundary with the first subfield is as follows. In other words, the ON period of the transistor 116 in each sub-field is extremely short compared to the normal driving in which one vertical scan is performed in one frame. For this reason, the voltage at the pixel electrode 118 of the pixel to be turned on does not reach + V1 or −V1 in one writing operation, and may occur particularly in a low temperature state. In other words, it is assumed that as the number of times of on-pixel writing in one frame increases, the voltage of the pixel electrode 118 approaches + V1 or −V1 and saturates at a certain number of times. For this reason, if the number of divisions is increased closer to the boundary of the second subfield and the number of times of writing is almost saturated, it is not necessary to increase the number of times of writing.

  Note that the above reason does not necessarily have to be taken into account for the division of the second subfield. For example, as shown in FIG. 15, only the second subfield period SF6 located in the middle of the second subfield periods SF5 to SF7 is divided and the remaining second subfield periods SF5 and SF7 are divided. Or only the second subfield period SF7 farthest from the boundary among the second subfield periods SF5 to SF7 is divided and the remaining second subfield periods SF5 and SF6 are not divided. It may be. That is, only an arbitrary second subfield period among the second subfield periods SF5 to SF7 may be divided.

  The division ratio of the second subfield may be other than FIG. 11, FIG. 14, and FIG. For example, a subfield having a period length of “4”, for example, may be divided into two as “1.2” and “2.8”. However, because the period length of the subfields SF1 to SF4 is “1”, it is more preferable to set the period of the subfields SF5a, SF5b, etc. to a period length obtained by multiplying this period by an integer, that is, the second The division period of the subfield is considered to be advantageous in that one of the first subfield periods is used as a unit because it is not necessary to supply the count data with decimals to the multiplexer 213.

[Second Embodiment]
An electro-optical device according to a second embodiment will be described with reference to FIGS.
FIG. 19 shows subfields of the second embodiment. As is clear from the comparison between FIG. 19 and FIG. 10 showing the subfields of the first embodiment, the frame 1F of the second embodiment has a subfield that is turned off regardless of the gradation data. SF8 has been added.

  FIG. 16 shows the configuration of the start pulse generation circuit of the second embodiment, FIG. 17 shows the configuration of the data conversion circuit of the second embodiment, and FIG. 18 shows the configuration of the second embodiment. The signal waveform is shown. The electro-optical device according to the second embodiment includes the start pulse generation circuit 210 shown in FIG. 16 and the data conversion circuit 300 shown in FIG. 17 in order to operate using the subfield SF8. In the start pulse generation circuit 210, as shown in FIG. 16, count data Dc8 for generating a period corresponding to the subfield SF8 is supplied to the multiplexer 213a. In the data conversion circuit 300, as shown in FIG. 17, the display address control unit 330a outputs the S_off signal only when the start pulse DY indicates the subfield SF8.

  According to the electro-optical device of the second embodiment, when it is necessary to slightly increase or decrease one of the periods of the subfields SF1 to SF7 in order to finely adjust the gradation, the other subfields SF1 to SF3, Since the gradation can be finely adjusted by increasing / decreasing only the period of subfield SF8 by the length requiring the increase / decrease without increasing / decreasing the length of SF5 to SF7, the fine adjustment of the gradation is easy. It becomes possible to do.

[Third Embodiment]
The electro-optical device according to the third embodiment displays more gray levels than the electro-optical devices according to the first and second embodiments. An electro-optical device according to a third embodiment will be described with reference to FIGS.

  FIG. 23 shows subfields of the third embodiment. In the electro-optical device according to the third embodiment, one frame (1F) is displayed in FIG. 23 in order to display 64 gradations defined by the 6-bit gradation data D0 to D5 input to the electro-optical device. As shown, it has seven subfields SF1-SF7, seven subfields SF9-SF15, and subfield SF8. The lengths of the subfields SF1 to SF7 have a weight of “1” gradation, and the lengths of the subfields SF9 to SF15 have a weight of “8” gradation. In order to provide the threshold voltage Vth defined by the operating characteristics of the liquid crystal, the subfield SF8 is always turned on regardless of the gradation.

  The on / off states of the subfields SF1 to SF7 are defined by the lower 3 bits (D0 to D2) of the gradation data D0 to D5, while the on / off states of the subfields SF9 to SF15 are defined by the gradation data D0 to D5. It is defined by the upper 3 bits (D3 to D5) of D5. For example, when the gradation data D0 to D5 is “001010” indicating “10” gradation, the subfields SF6 and SF7 are turned on and the subfield SF9 is turned on. When D5 is “011100” indicating “28” gradation, the subfields SF4 to SF7 are turned on, and the subfields SF9 to SF11 are turned on.

As described above, the subfields SF1 to SF7 and the subfields SF9 to SF15 are divided between the subfields SF7 and SF9 according to the increase in the value of the lower bits (D0 to D2) and the value of the upper bits (D3 to D5). By selecting in order from the substantial boundary in the direction of the outside of the frame, the continuity of the selected subfields can be ensured as in the first embodiment.
Instead of dividing the 6-bit gradation data D0 to D5 into 3 bits, it is also possible to divide into 6 upper bits and 4 lower bits, for example.

20 shows the configuration of the start pulse generation circuit of the third embodiment, FIG. 21 shows the configuration of the data conversion circuit of the third embodiment, and FIG. 22 shows the configuration of the third embodiment. The operation of the electro-optical device is shown. In order to perform the above operation, the electro-optical device according to the third embodiment includes the start pulse generation circuit shown in FIG. 20 and the data conversion circuit supported by FIG.
In start pulse generation circuit 210, as shown in FIG. 20, count data Dc1 to Dc15 for generating periods corresponding to subfields SF1 to SF15 are supplied to multiplexer 213b. In the data conversion circuit 300, as shown in FIG. 21, the decoder 312b is supplied with the gradation data D0 to D6, outputs the subfield data SD1 to SD7, SD9 to SD15, and the display address control unit 330b The read signals RD1 to RD7 and RD9 to RD15 are output every time the start pulse DY indicates the subfields SF1 to SF15.

[Fourth Embodiment]
An electro-optical device according to a fourth embodiment will be described with reference to FIG.
FIG. 24 shows subfields of the fourth embodiment. As shown in FIG. 24, the electro-optical device according to the fourth embodiment basically turns on the subfield SF4, which is described in the first embodiment and should always be turned on regardless of the gradation data. On the other hand, it is turned off only when the gradation data is 0000. As a result, it is possible to increase the contrast and improve the image quality.

[Fifth Embodiment]
An electro-optical device according to a fifth embodiment will be described with reference to FIG.
FIG. 25 shows subfields of the fifth embodiment. As shown in FIG. 25, the electro-optical device according to the fifth embodiment continues the subfields to be selected according to the gradation at the boundary F between adjacent frames. In other words, the subfield is configured so that the boundary (reference point) P when the first subfield and the second subfield are sequentially selected according to the gradation and the frame boundary F coincide. ing.

Thus, the first subfield (SF1 to SF3) is backward from the boundary with respect to the time axis, and the second subfield (SF5 to SF7) is forward from the boundary with respect to the time axis. In the opposite direction to the first embodiment, selection is made in order according to the gradation. That is, in the fifth embodiment, the subfield selection direction is apparently directed to the center of the previous frame and the subsequent frame.
Therefore, in the fifth embodiment, the continuity is ensured although it differs from the other embodiments in that the selected subfield extends over two adjacent frames. As in the case of this embodiment, it is possible to avoid the occurrence of a gradation defect.

  The subfield when the technique according to the application example of the first embodiment described above (that is, the technique of dividing the second subfield into two or more) is applied to the fifth embodiment. For example, as shown in FIG. That is, the number of divisions of the second subfield is set so as to increase as it approaches the boundary P with the first subfield, so that the reverse is seen from the time axis direction, but the subfields SF5 and SF6 are reversed. The number of divisions of SF7 is, for example, 3 times, 2 times, and 1 time, respectively, as in the above application example.

[Sixth Embodiment]
An electro-optical device according to a sixth embodiment will be described. The electro-optical device according to the sixth embodiment includes the technology for ensuring the continuity of selected subfields and FRC (Frame Rate Control) modulation described in the first to fifth embodiments. It is characterized by combining.

  FRC modulation refers to displaying gray scales through a plurality of mutually continuous frames, rather than displaying gray scales through one frame period. For example, when displaying “11” gradation out of 64 gradations using two consecutive frames, “6” gradation is displayed in the first frame, and the second frame is displayed. “5” gradation is displayed. For example, when displaying “11” gradation out of 64 gradations using three consecutive frames, “4” gradation is displayed in the first frame, and the second frame is displayed. To display “4” gradation, and display “3” gradation in the third frame. As the gradations to be displayed become larger, such as 64 gradations, 128 gradations, and 256 gradations, a length corresponding to a subfield for displaying a low gradation, for example, “1” gradation. Since the length of the subfield having a large length must be shortened, the FRC modulation is particularly suitable for controlling on / off of the subfield for displaying a low gradation with high accuracy.

Here, the N bits constituting the gradation data are composed of upper M bits (M is a positive integer smaller than N) and lower (NM) bits, and the first subfield is the lower (N−M). M) having a first weight corresponding to the weight of the least significant bit in the bits, and a second subfield having a second weight corresponding to the weight of the least significant bit in the upper M bits, Assuming that the number of the plurality of frames is F,
The number b of the first subfield and the number c of the second subfield in each frame are b = (2 ^N−M −1) / F (1),
c = (2 ^M −1) (2)
Indicated by However, in the formula (1), when 2N-M-1 is not divisible by F (when a remainder is generated), the number b is set as a number obtained by adding 1 to the integer part of the quotient.
Further, assuming that the first weighting is α, the second weighting β is
β = α2 ^N−M / F (3)
Indicated by

In addition, regarding one frame, the number Z of selection patterns indicating the combination of selection / non-selection of the first and second subfields is:
Z = 2 ^M (b + 1) (4)
Indicated by Furthermore, it is preferable that the grayscale data is divided into upper bits and lower bits based on an optimal solution of M that minimizes the total number of the first and second subfields.
It should be noted that the above formulas (1), (2), and (4) do not take into account the subfields that should be always on and the subfields that should always be off.

Hereinafter, for 64 gradations 3FRC displaying 64 gradations defined by 6-bit gradation data using three continuous frames, the gradation data is divided into upper 2 bits and lower 4 bits. Let's take an example.
In this case, since N = 6, M = 2, and F = 3, b = 5 from the above equation (1), c = 3 from the above equation (2), β = 5.33α from the above equation (3), From the above equation (4), Z = 24.
This state will be described with reference to FIG. 30. As a result of distributing 15 subfields for 16 gradation display to be expressed by the lower 4 bits of the gradation data to the three frames through three frames, Five (b = 5) subfields SF1 to SF5 having the weight of the least significant bit are provided in each frame.
On the other hand, three (c = 3) subfields SF7 to SF9 corresponding to the weight of the least significant bit among the upper 2 bits of the gradation data are provided in each frame. Specifically, when the weight of the least significant bit of the gradation data is “1”, the weight of the least significant bit of the upper 2 bits of the gradation data is “16”, which is distributed over three frames. As a result, the period length of the subfields SF7 to SF9 is “5.33” (when the period length of the subfields SF1 to SF5 is “1”).
After all, each frame is provided with a total of nine subfields: subfields SF1 to SF5 corresponding to the lower 4 bits, SF7 to SF9 corresponding to the upper 2 bits, and subfield SF6 to be always on. Yes.

  In FIG. 30, since the number of subfields SF1 to SF5 corresponding to the lower bits is 5, and the number of subfields SF7 to SF9 corresponding to the upper bits is 3, the selection pattern is 24 (= ( 5 + 1) × (3 + 1)) types. This point is also clear from Z = 24.

  FIG. 31 is a chart showing selection patterns to be selected in each frame in the case of 64 gradations 3FRC. For example, when the gradation data indicates “7” gradation (000111), the first frame forms the selection pattern 3 shown in FIG. 30 among the subfields included in the first frame. The subfields necessary for the selection are selected, that is, the subfields SF3 to SF5 are selected. In the second frame, among the subfields included in the second frame, the selection pattern 2 shown in FIG. The subfields necessary for constructing are selected, that is, the subfields SF4 and F5 are selected, and the third frame also constitutes the selection pattern 2 among the subfields included in the third frame. The subfields necessary for the selection are selected, that is, the subfields SF4 and SF5 are selected.

  FIG. 27 is a diagram showing a configuration of a data conversion circuit for 64-gradation 3FRC. As shown in this figure, the data conversion circuit 300s includes a write address control unit 310s, a display address control unit 330s, a frame memory 321s, and a decoder 312s, as in the first embodiment.

The gradation data D0 to D5 are once written at the address indicated by the write address WAD in the storage area of the frame memory 312s, then read from the address indicated by the read address RAD, and output to the decoder 312s. The
Of the frame numbers specified by the signals FRD0 and FRD1, the decoder 312s corresponds to the subfield period defined by the subfield numbers specified by the signals SFD0 to SFD3 (details are shown in the truth table shown in FIG. 28). The gradation data is decoded into the data signal Ds.
According to the data conversion circuit 300s, for example, in the gradation data (000001) indicating the gradation “1”, the first frame FR1 is specified by the signals FRD0 and FRD1 among the three frames, and the subfield Of SF1 to SF9, when the subfield SF5 is specified by the signals SFD0 to SFD3, it is converted into a data signal Ds of “1” instructing that the pixel should be turned on.

  FIG. 29 shows the waveform of a 64-gradation 3FRC signal. The waveform of the signal shown in FIG. 29 is substantially the same as the waveform of the signal in the first embodiment.

Next, a description will be given of a case where 64 gradations 2FRC that displays 64 gradations defined by 6-bit gradation data using two frames are divided into upper 3 bits and lower 3 bits. To do.
In this case, since N = 6, M = 3, and F = 2, b = 4, c = 7 from the above equation (2), β = 4α from the above equation (3), due to the exception of the above equation (1), From the above equation (4), Z = 40.
This state will be described with reference to FIG. 33. Four (b = 4) subfields SF1 to SF4 having the weight of the least significant bit of the gradation data are provided in each frame, while the gradation data Seven (c = 7) subfields SF6 to SF12 corresponding to the weighting of the least significant bit among the upper three bits are provided in each frame.
When each period length of subfields SF1 to SF4 is “1”, each period length of subfields SF6 to SF12 is “4”.
After all, in each frame, there are a total of 12 subfields SF1 to SF4 corresponding to the lower 3 bits, 7 SF6 to SF12 corresponding to the upper 3 bits, and a subfield SF5 to be always turned on. Subfields are provided. Therefore, the selection patterns in one frame are 40 (= (4 + 1) × (7 + 1)) types as shown in FIG. This point is also clear from Z = 40.

  FIG. 34 is a chart showing a selection pattern to be selected in each frame in the case of 64 gradation 2FRC. For example, when the gradation data indicates “6” gradation (000110), the first frame forms the selection pattern 4 shown in FIG. 33 among the subfields included in the first frame. The subfields SF1 to SF4 necessary for the selection are selected, and in the second frame, the subfields necessary for configuring the selection pattern 3 shown in FIG. 33 among the subfields included in the second frame are selected. Fields SF2 to SF4 are selected.

  In the sixth embodiment, naturally, in addition to 64 gradations using 6-bit gradation data, 256 gradations using 8-bit gradation data are possible.

  As described above, according to the sixth embodiment, by using FRC modulation, it is possible to reduce the number of subfields with small weights to be provided in each frame. Since the period of the subfield can be increased, the writing time to the pixel can be extended. Thereby, it becomes easy to apply the data signal to the liquid crystal with high accuracy.

  Note that, by performing the operation described above with reference to FIG. 11 as an application example of the first embodiment, the second subfield is divided into a plurality of drives in the FRC of the sixth embodiment. Is possible.

[Seventh Embodiment]
An electronic device according to a seventh embodiment will be described.
FIG. 35 shows a configuration of an electronic apparatus according to the seventh embodiment. As shown in FIG. 35, the electronic apparatus mainly includes a display information output source 1000 that outputs display information such as an image signal, a display information processing circuit 1002 that sequentially generates a digital signal from the display information, The electro-optical device 1001 described in each embodiment, the driving circuit 1004 that drives the electro-optical device 1001, and includes the scan line driving circuit 130 and the data line driving circuit 140 described above, a clock generation circuit 1008, and a power supply circuit 1010. As representative electronic devices of the tenth embodiment, there are a projector, a mobile computer, and a mobile phone.

  36A shows the configuration of the projector, FIG. 36B shows the configuration of the mobile computer, and FIG. 36C shows the configuration of the mobile phone. As shown in FIG. 36A, the projector 1430 has the electro-optical device as the liquid crystal light modulation devices 100R, 100G, and 100B, and the mobile computer 1200 is as shown in FIG. Further, the display unit 1206 includes the above-described electro-optical device 100 and a backlight, and the mobile phone 1300 includes the above-described electro-optical device as a display unit as illustrated in FIG. Yes.

  The weighting of each subfield set in the above example can be adjusted in consideration of the liquid crystal characteristics and the like. In the above example, the liquid crystal display device has been described. However, the present invention can also be applied to electro-optical elements such as an electroluminescence (EL) display, a plasma display, and a digital micromirror device (DMD) display.

1 is a diagram illustrating a configuration of an electro-optical device according to a first embodiment. It is a figure which shows the structure of the pixel provided in the display part of 1st Embodiment. 1 is a diagram illustrating a structure of an electro-optical device according to a first embodiment. 1 is a diagram illustrating a configuration of a data line driving circuit according to a first embodiment. FIG. It is a figure which shows the structure of the start pulse generation circuit of 1st Embodiment. 3 is a time chart illustrating an operation of the start pulse generation circuit according to the first embodiment. It is a figure which shows the structure of the data converter circuit of 1st Embodiment. It is a figure which shows the truth table which the decoder of 1st Embodiment uses. It is a time chart which shows the waveform of the signal of 1st Embodiment. It is a figure which shows the subfield of 1st Embodiment. It is a figure which shows the subfield which concerns on the application example of 1st Embodiment. It is a figure which shows the structure of the start pulse generation circuit of the application example of 1st Embodiment. (A) is a figure which shows the gradation-transmittance characteristic of 1st Embodiment, (b) is a figure which shows the gradation-transmittance characteristic of an application example. It is a figure which illustrates the case where the division | segmentation number is not uniform in an application example. It is a figure which illustrates the case where the subfield which should be divided | segmented in an application example differs. It is a figure which shows the structure of the start pulse generation circuit of 2nd Embodiment. It is a figure which shows the structure of the data converter circuit of 2nd Embodiment. It is a time chart which shows the waveform of the signal of 2nd Embodiment. It is a figure which shows the subfield of 2nd Embodiment. It is a figure which shows the structure of the start pulse generation circuit of 3rd Embodiment. It is a figure which shows the structure of the data converter circuit of 3rd Embodiment. FIG. 10 is a diagram illustrating an operation of an electro-optical device according to a third embodiment. It is a figure which shows the subfield of 3rd Embodiment. It is a figure which shows the subfield of 4th Embodiment. It is a figure which shows the subfield of 5th Embodiment. It is a figure which illustrates the case where the division | segmentation number is not uniform in 5th Embodiment. It is a figure which shows the structure of the data converter circuit of 6th Embodiment. It is a figure which shows the truth table which the decoder of 6th Embodiment uses. It is a time chart which shows the waveform of the signal of 6th Embodiment. It is a figure which shows the subfield of 6th Embodiment. It is a figure which shows the selection pattern in each frame of 6th Embodiment. It is a figure which shows the structure of the data converter circuit of 6th Embodiment. It is a figure which shows the subfield of 6th Embodiment. It is a figure which shows the selection pattern in each frame of 6th Embodiment. It is a figure which shows the structure of the electronic device of 7th Embodiment. It is a figure which shows the structure of a projector, a mobile type computer, and a mobile telephone.

Explanation of symbols

101a Display unit 150 Oscillation circuit 200 Timing signal generation circuit 300 Data conversion circuit 130 Scan line drive circuit 140 Data line drive circuit

Claims (35)

An electro-optic element that causes the electro-optic element to display the gradation by turning on the electro-optic element during a period corresponding to gradation data that defines gradation to be displayed through the frame period. Driving method,
A plurality of mutually continuous first subfield periods used for securing a period corresponding to the gradation data, and a plurality of first subfield periods, each of which is continuous with the plurality of first subfield periods. A plurality of second subfield periods consecutive to each other substantially corresponding to the length of the total period of the field period and one first subfield period are defined as the plurality of first subfield periods and the plurality of subfield periods. The first subfield period and the second subfield period that are located farthest from the boundary from the first subfield period and the second subfield period that are located in contact with the boundary of the second subfield period A selection step of sequentially selecting in accordance with the gradation data in the direction of
And a driving step of turning on the electro-optic element during the selected subfield period. The method of driving an electro-optic element according to claim 1, wherein the plurality of first subfield periods and the plurality of second subfield periods are included in the same frame period. A part of the plurality of first subfield periods and a part of the plurality of second subfield periods are included in one frame period of two consecutive frame periods, and the other subfields The electro-optical element driving method according to claim 1, wherein the period is included in the other frame period. The partial subfield period is one of the plurality of first subfield periods and the plurality of second subfield periods, and the other subfield period is the other subfield period. The electro-optical element driving method according to claim 3, wherein the driving period is a subfield period. The method of driving an electro-optical element according to claim 1, wherein, in the driving step, a period during which the electro-optical element is turned on is inserted into the boundary regardless of the gradation data. The drive step includes inserting a period during which the electro-optic element is turned off when the gradation data represents zero and the electro-optic element is turned on at the boundary otherwise. 2. A method for driving an electro-optical element according to 1. When the second subfield period is selected in the selection step,
2. The electro-optic according to claim 1, wherein in the driving step, at least one second subfield period among the selected second subfield periods is divided into a plurality of divided periods and turned on. Device driving method. 8. The second subfield period at a position near the boundary among the selected second subfield periods is preferentially divided and turned on in the driving step. Driving method of the electro-optic element. When two or more second subfield periods are selected in the selection step,
In the driving step, the second subfield period that is the two or more second subfield periods selected and is adjacent to each other among the second subfield periods that are adjacent to each other is the second subfield period that is close to the boundary. 9. The method of driving an electro-optic element according to claim 8, wherein the number of divisions is equal to or less than the number of divisions of the two subfield periods. 8. The method of driving an electro-optic element according to claim 7, wherein in the driving step, all of the selected second subfield periods are divided and turned on. The electro-optical element driving method according to claim 7, wherein in the driving step, at least one divided period of the plurality of divided periods corresponds to one first subfield period. The gradation data is composed of N bits (N is an integer equal to or greater than 2) for defining the gradation having 2 N power types,
The upper M bits of the N bits define a gray level to be displayed by the plurality of second subfield periods;
The lower (N−M) bits of the N bits define gray levels to be displayed by the plurality of first subfield periods,
The M is an optimal solution of M given when it is assumed that the frame period includes (2 ^N−M −1) first subfield periods. Driving method of electro-optical element. The gradation data is composed of N bits (N is an integer equal to or greater than 2) for defining the gradation having 2 N power types,
The length of each of the second subfield periods corresponds to the length of a period for representing a gradation defined by the least significant bit among the M bits on the upper side included in the N bits,
The number of the plurality of second subfield periods corresponds to a maximum number represented by the M bits,
The length of each of the first subfield periods is a length of a period for representing a gray scale defined by the least significant bit among the lower (NM) bits included in the N bits. Is equivalent to
2. The electro-optic element driving method according to claim 1, wherein the number of the plurality of first subfield periods corresponds to a maximum number represented by the (N−M) bits. The electro-optic element is turned on during the period corresponding to the gradation data that defines the gradation to be displayed through a plurality of frame periods, thereby causing the electro-optic element to display the gradation. An optical element driving method comprising:
A plurality of mutually continuous first subfield periods used for specifying a period corresponding to the grayscale data included in each frame period constituting the plurality of frame periods, and the plurality of first subfields A plurality of second subfield periods that are continuous with each other and each have a length equal to or greater than the total period of all the first subfield periods included in the plurality of frame periods. The boundary from the first subfield period and the second subfield period located in contact with the boundary between the plurality of first subfield periods and the plurality of second subfield periods for each frame period. Selection step of sequentially selecting according to the gradation data in the direction of the first subfield period and the second subfield period located farthest from the first subfield period ,
And a driving step of turning on the electro-optic element during the selected subfield period for each frame period. The selection step displays the number of first subfield periods to be selected for each frame period through the plurality of first subfield periods included in the plurality of frame periods of the grayscale data. The method of driving an electro-optical element according to claim 14, wherein the power gradation is determined according to a gradation data portion that defines a power gradation. In the selecting step, the gradation to be displayed through the plurality of frame periods, and the sub-period to be selected from the plurality of first subfield periods and the plurality of second subfield periods in each frame period. The method of driving an electro-optical element according to claim 14, wherein the selection is made according to a table that defines a correspondence relationship with the position of the field period. When the second subfield period is selected in the selecting step, at least one second subfield period among the selected second subfield periods is divided into a plurality of divided periods in the driving step. The electro-optic element driving method according to claim 14, wherein the electro-optic element is turned on. 18. The second subfield period close to the boundary among the selected second subfield periods is preferentially divided and turned on in the driving step. Driving method of the electro-optic element. When two or more second subfield periods are selected in the selection step, the second subfield periods adjacent to each other in the two or more second subfield periods selected in the driving step are selected. 19. The electro-optic element according to claim 18, wherein the second subfield period far from the boundary is turned on by dividing it into the same number or less as the number of divisions of the second subfield period close to the boundary. Driving method. 18. The method of driving an electro-optical element according to claim 17, wherein in the driving step, all of the selected second subfield periods are divided and turned on. 18. The method of driving an electro-optic element according to claim 17, wherein in the driving step, at least one of the plurality of divided periods corresponds to one first subfield period. The gradation data is composed of N bits (N is an integer equal to or greater than 2) for defining the gradation having 2 N power types,
The upper M bits of the N bits define a gray level to be displayed by the plurality of second subfield periods;
The lower (N−M) bits of the N bits define gray levels to be displayed by the plurality of first subfield periods,
The M is given when it is assumed that the frame period includes (2 ^N−M −1) / F first subfield periods (F represents the number of the plurality of frames). The method of driving an electro-optical element according to claim 14, wherein When (2 ^N−M −1) / F generates a remainder, the number obtained by adding 1 to the integer part of the quotient of (2 ^N−M −1) / F as the number of the first subfield period The method of driving an electro-optical element according to claim 22, wherein: A method of driving an electro-optic element that displays a gradation on the electro-optic element in units of frame periods,
Two or more first subfield periods that are adjacent to each other on either the front side or the rear side in time with respect to a reference point existing in the frame period and for turning on or off the electro-optic element Are sequentially selected from the reference point toward the one side according to the value indicated by the lower bits of the data defining the gradation,
One or more second subfield periods that are present on or adjacent to each other on either the front side or the rear side in time with respect to the reference point, and for turning on or off the electro-optic element. The second subfield period in which one period is set to be longer than the total period of the plurality of first subfield periods is determined according to the value indicated by the upper bits of the data excluding the lower bits. A selection step of sequentially selecting from the point toward the other side;
And a driving step of continuously turning on (or turning off) the electro-optic element during the selected first and second subfield periods. When the second subfield period is selected in the selection step,
25. The electro-optic according to claim 24, wherein, in the driving step, at least one second subfield period among the selected second subfield periods is divided into a plurality of divided periods and turned on. Device driving method. 26. In the driving step, among the selected second subfield periods, the second subfield period located near the boundary is preferentially divided and turned on. Driving method of the electro-optic element. When two or more second subfield periods are selected in the selection step,
In the driving step, the second subfield period that is the two or more second subfield periods selected and is adjacent to each other among the second subfield periods that are adjacent to each other is the second subfield period that is close to the boundary. 27. The method of driving an electro-optic element according to claim 26, wherein the number of divisions is equal to or less than the number of divisions of the two subfield periods. 25. The method of driving an electro-optical element according to claim 24, wherein in the driving step, all of the selected second subfield periods are divided and turned on. 25. The electro-optic element driving method according to claim 24, wherein, in the driving step, at least one of the plurality of divided periods corresponds to one first subfield period. An electro-optic element that causes the electro-optic element to display the gradation by turning on the electro-optic element during a period corresponding to gradation data that defines gradation to be displayed through the frame period. Drive device
A plurality of consecutive first subfield periods used for specifying a period corresponding to the grayscale data, and a plurality of first subfield periods that are consecutive to each other, each of the plurality of first subfield periods. A plurality of second subfield periods consecutive to each other substantially corresponding to the length of the total period of the field period and one first subfield period are defined as the plurality of first subfield periods and the plurality of subfield periods. Of the first subfield period and the second subfield period that are located farthest from the boundary from the first subfield period and the second subfield period that are located adjacent to the boundary of the second subfield period A selection circuit that selects the direction according to the gradation data;
A drive circuit for turning on the electro-optic element during the selected sub-field period. The electro-optic element is turned on during the period corresponding to the gradation data that defines the gradation to be displayed through a plurality of frame periods, thereby causing the electro-optic element to display the gradation. An optical element driving device comprising:
A plurality of mutually continuous first subfield periods used for specifying a period corresponding to the grayscale data included in each frame period, and the plurality of first subfield periods, A plurality of mutually continuous second subfield periods having a length equal to or longer than the total period of all the first subfield periods included in the plurality of frame periods, for each frame period. The first subfield period located closest to the boundary from the first subfield period and the second subfield period located in contact with the boundary between the plurality of first subfield periods and the plurality of second subfield periods. A selection circuit that selects in accordance with the grayscale data in the direction of the subfield period and the second subfield period,
A drive circuit for an electro-optic element, comprising: a drive circuit that turns on the electro-optic element during the selected subfield period for each frame period. A drive device for an electro-optic element that displays gradation on the electro-optic element in units of frame periods,
Two or more first subfield periods that are adjacent to each other on either the front side or the rear side in time with respect to a reference point existing in the frame period and for turning on or off the electro-optic element Are sequentially selected from the reference point toward the one side according to the value indicated by the lower bits of the data defining the gradation,
One or more second subfield periods that are present on or adjacent to each other on either the front side or the rear side in time with respect to the reference point, and for turning on or off the electro-optic element. The second subfield period in which one period is set to be longer than the total period of the plurality of first subfield periods is determined according to the value indicated by the upper bits of the data excluding the lower bits. A selection circuit for selecting in order from the point toward the other side;
And a driving circuit for continuously turning on (or turning off) the electro-optic element during the selected first and second subfield periods. A display device including a plurality of electro-optic elements arranged in a matrix and displaying an image related to an electronic device;
An electronic apparatus comprising: the electro-optic element driving device according to claim 30. A display device including a plurality of electro-optic elements arranged in a matrix and displaying an image related to an electronic device;
An electronic apparatus comprising: the electro-optic element driving device according to claim 31. A display device including a plurality of electro-optic elements arranged in a matrix and displaying an image related to an electronic device;
An electronic apparatus comprising: the electro-optical element driving device according to claim 32.

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