JP2009128405A - Electro-optical device, its driving method, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve gradation expression characteristics when pixels are turned off or on in sub-fields obtained by dividing one field into a plurality. <P>SOLUTION: The pixels are greater in the rate of change in brightness on one of a high gradation side than on a low gradation side with respect to the ratio at which the application period of an off voltage or on voltage occupies over the period of each one field. The image for one field to be displayed is analyzed, and is judged whether or not there are few pixels to be made to one gradation on the high gradation side or the low gradation side. When such pixels are judged to be few, control is performed so that the on voltage or off voltage may be applied according to the gradations to each of the pixels for every sub-field obtained by equally dividing the one field into 16. On the other hand, the pixels are judged not to be few, each term of the 16 subfields is shorten and control is performed so that the on voltage or off voltage may be applied according to the gradations to each of the pixels for every sub-field shortened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a technique for expressing gradation by dividing one field into a plurality of subfields and turning on or off pixels in each subfield.

When performing gradation display in an electro-optical device having a display element such as a liquid crystal capacitor in a pixel,
The following technique has been proposed as an alternative to the voltage modulation method. In other words, one field is equally divided into a plurality of subfields, and pixels (liquid crystal capacitors) are turned on or off in each equally divided subfield to change the proportion of time during which the pixels are turned on in one field. A technique for performing gradation display has been proposed (Patent Document 1).
reference).
JP 2003-114661 A

However, in the above technique, for example, in the normally white mode, the expression on the bright gradation side is reduced, specifically, the gradation difference in the area on the bright side when displaying the gray scale is There was a problem that it appeared larger than the difference in gradation in other regions.
The present invention has been made in view of the above-described circumstances, and one of its purposes is an electro-optical device with improved gradation expression characteristics when a pixel is turned on or off in a subfield obtained by dividing one field into a plurality of fields. An object of the present invention is to provide a driving method and an electronic apparatus.

In order to solve the above problems, the present invention includes a plurality of pixels, and each of the plurality of pixels has a rate of change in brightness with respect to a ratio of an on-voltage or off-voltage application period over a period of one field. In an electro-optical device in which one of the high gradation side and the low gradation side is larger than the other, the image to be displayed is analyzed, and the number of pixels to be the one gradation on the high gradation side or the low gradation side is small And a determination circuit for determining whether or not the number of pixels is small in the determination circuit, for each subfield obtained by equally dividing one field into a plurality of sub-fields, the on-voltage according to the gradation Alternatively, when it is determined that an off voltage is applied while it is determined that the number of pixels is not small, each period of a plurality of subfields is shortened, and for each shortened subfield, For each element, characterized by comprising a control circuit for controlling as ON voltage or an OFF voltage is applied according to the tone, the. According to the present invention, when the rate of change in brightness is higher than the other on one side of the high gradation side or the low gradation side, if it is determined that the number of pixels for the one gradation is small, Since the period is shortened, the difference in gradation on one side can be improved small.

Here, in the present invention, the application of an on voltage or an off voltage to each of the plurality of subfields according to the gradation is determined with reference to a table, and the contents of the table are determined by the determination circuit. It is good also as a structure changed according to this determination result. Further, in this configuration, a temperature sensor that detects the ambient temperature of the pixel may be provided, and the contents of the table may be changed according to the detected temperature.
The present invention can be conceptualized not only as an electro-optical device, but also as a driving method of the electro-optical device, and also as an electronic apparatus having the electro-optical device.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment of the invention. As shown in this figure, the electro-optical device 1 includes a display panel 10, a video processing circuit 20, a timing control circuit 30, a data conversion circuit 40, and a temperature sensor 50.

FIG. 2 is a diagram illustrating a configuration of the display panel 10 in the electro-optical device 1, and FIG. 3 is a diagram illustrating a configuration of the pixels 110 in the display panel 10.
As shown in FIG. 2, the display panel 10 has a configuration in which a Y driver (scanning line driving circuit) 130 and an X driver (data line driving circuit) 140 are arranged around the display area 100. In the present embodiment, in the display area 100, 1080 scanning lines 112 are provided so as to extend in the row (horizontal direction), and 1920 data lines 114 extend in the column (vertical direction). The scanning lines 112 are provided so as to be electrically insulated from each other. Further, 1080 scanning lines 112 and 1920 columns of data lines 11
Corresponding to the intersection with 4, the pixels 110 are arranged. Therefore, in this embodiment, the pixels 110 are arranged in a matrix of 1080 vertical rows × horizontal 1920 columns in the display region 100, but the present invention is not limited to this arrangement.

FIG. 3 shows a total of 4 pixels of 2 × 2 corresponding to the intersection of the i row and the (i + 1) row adjacent to it by 1 row and the j column and the (j + 1) column adjacent to the right by 1 column. The structure of is shown. In addition,
i and (i + 1) are symbols for generally indicating the row in which the pixels 110 are arranged, and are integers of 1 to 1080 in this description. J and (j + 1) are symbols for generally indicating a column in which the pixels 110 are arranged, and are integers of 1 or more and 1920 or less.

As shown in FIG. 3, each pixel 110 includes an n-channel transistor 116 and a liquid crystal capacitor 120. Here, since each pixel 110 has the same configuration, if the configuration is represented by a pixel located in the i-th row and j-th column, the gate electrode of the transistor 116 in the pixel 110 in the i-th row and j-th column is scanned in the i-th row. While being connected to the line 112, its source electrode is connected to the data line 114 in the j-th column, and its drain electrode is connected to the pixel electrode 118.
Although not particularly shown, the display panel 10 has a configuration in which a pair of substrates of an element substrate and a counter substrate are bonded together with a certain gap therebetween, and the liquid crystal 105 is sealed in the gap. Among them, the element substrate includes a scanning line 112, a data line 114, and a transistor 116.
While the pixel electrode 118 and the like are formed, the common electrode 108 is formed on the counter substrate, and these electrode forming surfaces are bonded together with a certain gap so as to face each other. For this reason, in this embodiment, the liquid crystal capacitor 120 is configured by the pixel electrode 118 and the common electrode 108 sandwiching the liquid crystal 105.

In this embodiment, a constant voltage LCcom is applied to the common electrode 108 in terms of time. In the present embodiment, if the effective voltage value held in the liquid crystal capacitor 120 is close to zero, the transmittance of light passing through the liquid crystal capacitor is maximized to display white, while the effective voltage value increases. The normally white mode in which the amount of transmitted light decreases and finally the black display with the minimum transmittance is set.
In the pixel 110, a storage capacitor 109 is formed for each pixel. This storage capacity 10
One end of 9 is connected to the pixel electrode 118 (the drain of the transistor 116), while the other end is commonly connected to the capacitor line 107 over all pixels. The capacity line 107 is maintained at a constant time, for example, the same voltage LCcom as the common electrode 108.

In this configuration, a selection voltage is applied to the scanning line 112 to turn on the transistor 116 (
When the data signal is supplied to the pixel electrode 118 through the data line 114 and the transistor 116 in the ON state, the scanning line 112 to which the selection voltage is applied and the data line 114 to which the data signal is supplied are crossed. In the corresponding liquid crystal capacitor 120, a differential voltage between the voltage of the data signal and the voltage LCcom applied to the common electrode 108 is written. After that, when the scanning line 112 becomes a non-selection voltage, the transistor 116 is turned off (non-conducting). However, in the liquid crystal capacitor 120, the voltage written when the transistor 116 is turned on depends on the capacitance. Retained.

In the case of gradation display by a normal analog method, the data signal is set as a voltage corresponding to the gradation,
Although written in the liquid crystal capacitor 120, in this analog method, display unevenness due to wiring resistance or the like occurs, or a separate D / A conversion circuit or the like is required.
For this reason, in this embodiment, the voltage of the data signal is a binary value of an on-voltage that turns on the liquid crystal capacitor 120 or an off-voltage that turns off the liquid crystal capacitor 120. Thus, the liquid crystal capacity 1
In order to perform gradation display using only the two values of the on-voltage and off-voltage, the ratio of the period during which the on-voltage (or off-voltage) is applied in one field, which is the basic period, is represented by gradation. Should be changed accordingly. Note that one field here means a period required to form an image for one sheet, and is synonymous with a frame in the non-interlace method, and is constant at 16.7 milliseconds (one frequency of 60 Hz). It is.

FIG. 6 is a diagram illustrating the relationship between the number of subfields to which the ON voltage is applied (number of left-shifted pulses) and the transmittance of the liquid crystal capacitor 120 when one field is equally divided into 80 subfields. . Note that the actual transmittance of the liquid crystal capacitor 120 is approximately proportional to the integral value of the period during which the on-voltage is applied, so that the subfield to which the on-voltage is applied is temporally moved forward and continuous. In this figure, the transmittance is shown as a relative value normalized with the darkest value being 0% and the brightest value being 100%.

As shown in this figure, by increasing or decreasing the number of subfields to which the ON voltage is applied in one field, the transmittance changes from approximately 0 to 100%, so that many gradations can be expressed. Is possible. However, in the region B where the number of left-shifted pulses is small in the normally white mode, it can be seen that the change in transmittance is larger than the other regions as the number of left-shifted pulses increases and decreases. This means that if the number of equal divisions in one field is small, the gradation expression in the bright area B is deteriorated.
That is, FIG. 6 shows the case where the number of subfields that equally divide one field is “80”, but when this is reduced to, for example, “16”, this corresponds to the transmittance of black circles in FIG. As a result, the difference in bright gradation in the region B increases. In order to improve the difference in gradation in the region B, the number of subfields to be divided in one field may be increased. However, since it is necessary to transfer data in each divided subfield, there is a limitation. There are many.

Therefore, in the present embodiment, when the gradation expression in a bright region is not important, the normal image display mode is set, and a subfield obtained by equally dividing one field into “16” as shown in FIG. The on voltage or the off voltage is applied in each subfield. Here, a period of one subfield obtained by equally dividing one field into 16 subfields in the normal video display mode is represented by Ta.
On the other hand, when emphasis is placed on gradation expression in a bright region, the high gradation display mode is set, and FIG.
), Each of the 16 subfields is shortened to reduce the difference in gradation in a bright region. Here, when the period of one subfield in the high gradation display mode is Tb, naturally, Ta> Tb. In the figure, for 16 subfields, for convenience, sf1, sf2, sf3,.
16 is written.
Note that when a subfield constituting one subfield is shortened in the high gradation display mode, a null period is generated, and the state of the liquid crystal capacitor 120 in the null period is as follows.
The on or off voltage written in the immediately preceding subfield sf16 is held as it is.
In the present embodiment, whether to set the normal video display mode or the high gradation display mode, a gradation histogram for one field in the pixel 110 of vertical 1080 rows × horizontal 1920 columns is created, and a bright gradation component is created. Judgment is made based on whether or not there are few.
In the present embodiment, the number of subfields constituting one field is “16”, but it goes without saying that the number is not limited to this.

Returning the description to FIG. 1 again, the video processing circuit 20 supplies various kinds of video data Din supplied from an external upper circuit (not shown) in synchronization with the synchronization signal Sync and designating the gradation of each pixel 110. Video processing, for example, noise reduction processing, ghost removal processing, and the like are performed and output as video data Da. Also, the video processing circuit 20 creates a gradation histogram every time one field of the video data Da subjected to various video processes is output, and sets the normal video display mode or the high gradation display mode. Judge about. The video processing circuit 20 outputs a signal a / b indicating the determination result.
The timing control circuit 30 generates a signal a / from one field defined by the synchronization signal Sync.
The subfields sf1 to sf16 are divided in a period according to the determination result indicated by b, and the Y driver 130 and the X driver 1 are divided according to the subfields sf1 to sf16.
40 is controlled.

In general, the data conversion circuit 40 converts the gradation specified by the video data Da into data Dsf that specifies an on-voltage or an off-voltage for each of the subfields sf1 to sf16.
It is to convert to. For this reason, the data conversion circuit 40 includes a field memory 410, a look-up table (LUT) 412, LUT selection circuits 414 and 418, an LUT expansion circuit 416, and an LUT synthesis circuit 420.
Among these, the field memory 410 stores the video data Da for at least one field under the control of the timing control circuit 30 and reads the stored video data Da for each of the subfields sf1 to sf16.

A table synthesized by the LUT synthesis circuit 420 is set in the LUT 412. This table defines whether the on-voltage or the off-voltage is set for each of the subfields sf1 to sf16 with respect to the gradation defined by the video data Da read from the field memory 410.
Here, in order to convert to data Dsf, in addition to video data Da, information indicating which of the subfields is to be used is necessary. Therefore, the timing control circuit 30
Supplies the data Nsf indicating the subfield number to the LUT 412, and the LUT 412 specifies the gradation and data Nsf specified by the video data Da read from the field memory 410.
The data Dsf corresponding to the subfield indicated by is output.

Incidentally, the conversion contents of the table synthesized by the LUT synthesis circuit 420 are roughly as follows. That is, for the brightest gradation, the off-voltage is specified for all subfields, and the subfield for specifying the on-voltage starting from the subfield sf1 extends backward in time as the gradation becomes darker. It has become. In addition,
Since the response speed of the liquid crystal is slow, as described in Patent Document 1, by inserting a subfield for applying an off voltage between subfields for applying an on voltage, 1
It is possible to express the number of gradations more than the number of subfields in the field.
In addition, as described above, in the present embodiment, one subfield is set as the period Ta when an image for one field is displayed in the normal video display mode, and one subfield is displayed when the image is displayed in the high gradation display mode. Since the field is changed short to the period Tb, it is necessary to change the conversion contents of the table in two display modes.
The conversion contents of the table are experimentally determined in accordance with the characteristics of the display panel 10 in both the normal video display mode and the high gradation display mode.

The LUT selection circuit 414 and the LUT expansion circuit 416 are configured to change the conversion contents of this table. The LUT selection circuit 414 includes a table a used in the normal video display mode,
The table b used in the high gradation display mode is code-compressed and stored in advance, and one of the tables is selected according to the determination result indicated by the signal a / b. Specifically, the LUT selection circuit 414 selects the table a when the signal a / b indicates that the normal video display mode is selected, and indicates that the high gradation display mode is selected. In this case, the table b is selected. For code compression, various methods such as a run length method are used. The LUT expansion circuit 416 expands (expands) the table selected by the LUT selection circuit 414.

Thereby, a table of the normal video display mode or the high gradation display mode indicated by the signal a / b can be obtained. This table may be set in the LUT 412 as it is,
Since the characteristics shown in FIG. 6 also change depending on the temperature, in this embodiment, the conversion contents of the table are also changed depending on the temperature.
The temperature sensor 50 detects the temperature in the vicinity of the display panel 10, particularly the pixel 110, and outputs detected temperature data Tmp. The LUT selection circuit 418 has a plurality of tables corresponding to the temperature range in advance, and outputs a table having the temperature indicated by the data Tmp as a range.
The conversion contents of this table are also experimentally determined according to the temperature characteristics of the display panel 10.
The LUT synthesis circuit 420 includes the table expanded by the LUT expansion circuit 416, the LUT
The selection circuit 418 synthesizes the table corresponding to the temperature and sets it in the LUT 412.
Therefore, the conversion content of the table set in the LUT 412 corresponds to the normal video display mode or the high gradation display mode, and the one reflecting the temperature characteristics of the display panel 10 is updated for each field. .

In such a configuration, the video processing circuit 20 performs video processing on the video data Din supplied from the external upper circuit, and a bright gradation component is present in the pixels of the image for one field expressed by the processed video data Da. When it is determined that there are few, the display panel 10 is driven in a normal video display mode in which one field is equally divided into subfields sf1 to sf16.

Specifically, as shown in FIG. 5A, the timing control circuit 30 has 1, 2, 3,... In each of the subfields sf1 to sf16 that are equally divided into 16 fields.
The scanning signal G1, which sequentially becomes H level (selection voltage VH), on the scanning line 112 in the 1080th row,
The Y driver 30 is controlled so that G2, G3,..., G1080 are supplied. That is,
The scanning line 112 is selected in the order of the 1st to 1080th rows in each of the subfields sf1 to sf16. In the figure, in the normal video display mode, 1 in each subfield.
A period in which the scanning lines 112 for the row are selected (a period in which the scanning signal is at the H level) is denoted by Ha.

The timing control circuit 30 reads from the field memory 410 video data Da corresponding to one row of pixels in the 1st to 1920th columns located on the scanning line for setting the scanning signal to the H level in accordance with the control for the Y driver 30. Thereby, in the LUT 412, the video data Da for one row located on the scanning line is converted into data Dsf corresponding to the subfield number indicated by the data Nsf. Here, in the LUT 412, conversion contents reflecting the normal video display mode and the temperature of the display panel 10 are set.
Then, the timing control circuit 30 transfers the converted data Dsf corresponding to the pixels in the 1st to 1920th columns to the X driver 140, and the X driver 140 transfers the data corresponding to the transferred pixels in the 1st to 1920th columns. Dsf is reconverted to the on or off voltage indicated by the signal, and the data signal 114 to the data line 114 in the 1st to 1920th columns is used as the data signals d1 to d1920.
According to the control of 0, the scanning signal of the row is supplied in accordance with the H level. When the scanning line 112 is at the selection voltage VH corresponding to the H level, the transistor 116 having the gate electrode connected to the scanning line 112 is turned on, so that the on or off voltage supplied to the data line 114 is changed to the pixel electrode. 118 to be applied.

In order to prevent a direct current component from being applied to the liquid crystal 105, there are two types of on-voltage, positive polarity and negative polarity, which are alternately used for each field period. Therefore, the X driver 140 supplies the on-voltage with a positive polarity if, for example, an on-voltage is indicated in the odd field, and if the on-voltage is indicated in the even field, the X driver 140 It becomes the composition to supply. Here, positive polarity means a higher side than the voltage LCcom applied to the common electrode 108, and negative polarity means a lower side than the voltage LCcom. Also,
The off voltage may be the voltage LCcom without dividing the polarity as long as the difference voltage of the liquid crystal capacitor 120 is zero.

The operation of supplying the data signal and writing to the pixel electrode in this way is the subfield sf1.
In each of ˜sf16, the scanning line 112 in the 1st to 1080th rows is repeated each time it is selected in order.
In such a normal video display mode, each of the subfields sf1 to sf16 is a period in which the period of one field is equally divided into 16, so that the gradation expression characteristic in a bright region is deteriorated as described above. Since the premise for the normal video display mode is that there are not many pixels with bright gradations, the deterioration of the expression characteristics is not noticeable.

On the other hand, when it is determined that there are not many (high) bright gradation components in the pixels of the image for one field expressed by the video data Da processed by the video processing circuit 20, the display panel 10 is driven in the high gradation display mode. Is done.
Specifically, the timing control circuit 30 sets each period of the subfields sf1 to sf16 to T
As shown in FIG. 5 (b), the scanning signals G1, G2, G3,... The Y driver 30 is controlled so that G1080 is supplied. In the figure, in the normal video display mode, the period during which one row of scanning lines 112 is selected in each subfield is denoted as Hb.

Here, the timing control circuit 30 reads and transfers the video data Da from the field memory 410 and controls the X driver 140 so that the period of each subfield is Ta.
This is the same as the normal video display mode except that the time is shortened from Tb to Tb. Also, the LUT 41
In 2, the conversion content reflecting the high gradation display mode and the temperature of the display panel 10 is set.
In such a high gradation display mode, each period of the subfields sf1 to sf16 is shortened to Tb, so that the gradation expression characteristic in a bright region can be improved as compared with the normal video display mode. In the high gradation display mode, on the other hand, a null period occurs, so that the gradation expression characteristic in a dark region may be deteriorated. Since there are many cases, even if the expression characteristics are lowered, it is not noticeable.

In the above embodiment, since the on or off voltage is applied to the pixel electrode 118 in each of the 16 subfields obtained by dividing one field, the influence of off-leakage is small as compared with the analog driving. The capacity value of the storage capacitor 109 may be small.

In the embodiment, the transmittance characteristic in the liquid crystal capacitor 120 is described as a normally white mode. However, if the effective voltage value held in the liquid crystal capacitor 120 is close to zero, the transmittance is minimized and black display is obtained. On the other hand, the amount of transmitted light increases as the effective voltage value increases, and finally a normally black mode in which white display with the maximum transmittance is achieved may be set.
In the case of the normally black mode, the gradation expression characteristic in a dark region is deteriorated. Therefore, in the above-described embodiment, the video processing circuit 20 performs one field as a normal image display mode when there are few dark gradation components. Is driven in the equally divided sub-field, while the low-gradation display mode may be shortened when the low-gradation component is not small (large). Further, when the normally black mode is set, the LUT selection circuit 414
The table a used in the normal video display mode and the table b used in the low gradation display mode may be stored, and any table may be selected according to the display mode. .

In the embodiment, a gradation histogram is created for an image for one field, and the display mode is determined for each field based on the gradation histogram. The display mode may be determined.
Furthermore, one pixel may be configured by three pixels of R (red), G (green), and B (blue) to perform color display. Further, the present invention is not limited to the transmissive type, and may be a reflective type or a semi-transmissive / semi-reflective type intermediate between the two.

<Electronic equipment>
Next, as an example of an electronic apparatus using the electro-optical device according to the above-described embodiment, a projector using the above-described electro-optical device 1 as a light valve will be described. FIG. 7 is a plan view showing the configuration of the projector.
As shown in this figure, a projector 2100 is provided with a lamp unit 2102 composed of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 2102 is separated into three primary colors of R (red), G (green), and B (blue) by three mirrors 2106 and two dichroic mirrors 2108 arranged inside. Are led to the light valves 10R, 10G and 10B corresponding to the respective primary colors. Note that B light has a longer optical path than other R and G colors, and therefore, in order to prevent the loss, B light passes through a relay lens system 2121 including an incident lens 2122, a relay lens 2123, and an exit lens 2124. Led.

In this projector 2100, three sets of electro-optical devices including the display panel 10 are provided corresponding to each color of R, G, and B, and video data corresponding to each color of R, G, and B is received from an external upper circuit. It is a configuration to be supplied. The configuration of the light valves 10R, 10G, and 10B is the same as that of the display panel 10 in the above-described embodiment, and R, G, and B of the timing control circuit (not shown in FIG. 7) provided corresponding to each color is provided. The data signal is driven for each subfield.
The lights modulated by the light valves 10R, 10G, and 10B are incident on the dichroic prism 2112 from three directions. And this dichroic prism 211
In 2, the light of R color and B color is refracted at 90 degrees, while the light of G color goes straight. Therefore, after the images of the respective colors are combined, a color image is projected onto the screen 2120 by the projection lens 2114.

The light valves 10R, 10G, and 10B include a dichroic mirror 2108.
Therefore, light corresponding to the primary colors of R, G, and B is incident, so there is no need to provide a color filter. The transmitted images of the light valves 10R and 10B are the dichroic prism 21.
12 is projected after being reflected by the light valve 12, while the transmitted image of the light valve 10G is projected as it is, so the horizontal scanning direction by the light valves 10R and 10B is the light valve 10G.
The image is reversed in the horizontal scanning direction according to the above, and an image with the left and right reversed is displayed.

In addition to the electronic device described with reference to FIG. 7, the electronic device includes a television, a viewfinder type / monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a television. Examples include a telephone, a POS terminal, a digital still camera, a mobile phone, and a device equipped with a touch panel. Needless to say, the electro-optical device according to the present invention is applicable to these various electronic devices.

1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment of the invention. FIG. 2 is a diagram showing a configuration of a display panel in the same electro-optical device. FIG. It is a figure which shows the structure of the pixel in the display panel. It is a figure which shows the field structure in the display panel. It is a figure for demonstrating the operation | movement in each subfield. It is a figure which shows the transmittance | permeability characteristic in the display panel. It is a figure which shows the structure of the projector to which the same electro-optical apparatus is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 10 ... Display panel, 20 ... Image processing circuit, 30 ... Timing control circuit, 40 ... Data conversion circuit, 50 ... Temperature sensor, 105 ... Liquid crystal, 108 ... Common electrode, 11
DESCRIPTION OF SYMBOLS 0 ... Pixel, 112 ... Scan line, 114 ... Data line, 116 ... Transistor, 120 ... Liquid crystal capacity, 130 ... Y driver, 140 ... X driver, 412 ... LUT, 414 ... LUT selection circuit, 2100 ... Projector

Claims (5)

Having a plurality of pixels,
The plurality of pixels each have an electro-optic in which the rate of change in brightness is greater on the high gradation side or the low gradation side than on the other with respect to the ratio of the on-voltage or off-voltage application period over one field period. In the device
A determination circuit that analyzes an image to be displayed and determines whether or not the number of pixels to be set to one of the high gradation side and the low gradation side is small;
When the determination circuit determines that the number of pixels is small, an on voltage or an off voltage is applied to each of the pixels for each subfield obtained by equally dividing a field into a plurality of subfields. While controlling
When it is determined that the number of pixels is not small, each period of the plurality of subfields is shortened, and an on voltage or an off voltage is applied to each of the pixels for each shortened subfield according to the gray level. A control circuit for controlling
An electro-optical device comprising: For each of the plurality of subfields, applying an on voltage or an off voltage according to the gradation is determined with reference to a table, and
The electro-optical device according to claim 1, wherein contents of the table are changed according to a determination result of the determination circuit. A temperature sensor for detecting the ambient temperature of the pixel;
The electro-optical device according to claim 2, wherein the contents of the table are changed according to the detected temperature. Having a plurality of pixels,
The plurality of pixels each have an electro-optic in which the rate of change in brightness is greater on the high gradation side or the low gradation side than on the other with respect to the ratio of the on-voltage or off-voltage application period over one field period. In the driving method of the apparatus,
Analyzing the image to be displayed and determining whether or not there are few pixels for one of the high gradation side or the low gradation side,
When it is determined that the number of pixels is small, control is performed so that an on voltage or an off voltage is applied to each of the pixels for each subfield obtained by equally dividing a field into a plurality,
If it is determined that the number of pixels is not small, each period of the plurality of subfields is shortened, and an on voltage or an off voltage is applied to each of the pixels for each shortened subfield depending on the gray level. A method for driving an electro-optical device, characterized by:   An electronic apparatus comprising the electro-optical device according to claim 1.

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