JP2009175214A - Electrooptical device, driving method thereof, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of scrolling noise without changing a driving frequency of a light source. <P>SOLUTION: An electrooptical device includes: a display panel which has a plurality of pixels and has an AC-driven light source irradiated with light; a memory in which supplied display data is stored and from which display data are read out; a control signal output circuit which outputs a control signal having a prescribed frequency; a driving circuit which scans and drives the display panel so that a period when the plurality of pixels are driven in accordance with display data read out from the memory is a scan period corresponding to the frequency of the control signal in each scan; and a control circuit which changes the scan period by changing the frequency of the control signal output from the control signal output circuit in a range of the prescribed number of frequencies at intervals of one or more scans and reads out display data stored in the memory synchronously with the control signal to supply the data to the driving circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for improving display quality in an electro-optical device such as a projector.

There is a projector that generates a reduced image using a light valve such as a liquid crystal panel, and enlarges and projects the reduced image using an optical system. As a light source used in such a projector, a high-pressure discharge lamp or the like is used, and AC driving using a pulse or a triangular wave is performed in order to extend its life (see Patent Document 1). As a result, the amount of light of the light source increases immediately after the polarity is switched, and thus the light source flickers at a frequency twice the driving frequency. On the other hand, the liquid crystal panel is driven at a constant frequency, for example, 50 Hz in the PAL system and 100 Hz in the double speed driving system, and flickers according to the driving frequency.

Here, depending on the relationship between the driving frequency of the light source and the driving frequency of the liquid crystal panel, the flickering components may interfere with each other to generate a low-frequency component, resulting in flickering or scrolling bands (scrolling noise). Display quality may be deteriorated. In order to improve this, a technology is disclosed in which the driving frequency of the light source is set to a frequency at which scroll noise is difficult to see with respect to the driving frequency of the liquid crystal panel (see Patent Document 2). Further, a technique for changing the driving frequency of the light source is disclosed irrespective of driving of the liquid crystal panel so that the interference component does not have regularity (see Patent Document 3).
JP 2003-36992 A JP 2003-156798 A JP 2006-72196 A

Here, in the technique of Patent Document 2, depending on the driving frequency of the liquid crystal panel, the driving frequency of the light source for reducing scroll noise may be a frequency that adversely affects the lifetime. In the technique of Patent Document 3, depending on the mode of changing the driving frequency of the light source, scroll noise may occur if the changed driving pulse is similar for each video frame. In order to achieve this, it is necessary to frequently change the drive frequency, which increases the circuit load.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electro-optical device, a driving method thereof, and a projector that can suppress the generation of scroll noise without changing the driving frequency of a light source. And

In order to solve the above-described problems, the present invention includes a display panel having a plurality of pixels and irradiating light to an AC-driven light source, a memory for storing supplied display data, and reading the display data. A control signal output circuit that outputs a control signal of a predetermined frequency and display data read from the memory are supplied, and a period for driving the plurality of pixels according to the display data in each scan is as follows: A drive circuit that scans and drives the display panel and a frequency of the control signal output from the control signal output circuit so as to have a scanning period according to the frequency of the control signal, and the frequency of the control signal for each scan By changing within a predetermined number range, the drive circuit is controlled to change the scanning period, and the display data stored in the memory is read in synchronization with the control signal. Providing an electro-optical device characterized by comprising a control circuit for supplying to said drive circuit by. According to the electro-optical device, the relationship between the blinking timing of the light source and the position of the scanning line selected at this timing can be irregularly changed by changing the scanning period for each scanning. The occurrence of scroll noise can be suppressed.

In another preferred embodiment, the control circuit outputs a timing signal defining the start timing of the scanning period to the driving circuit at a constant cycle, and reading of the display data stored in the memory is performed by the control signal. It is performed in synchronization with the timing signal. In this way, it is possible to change the scanning period and the blanking period while keeping the period of one scanning constant in each scanning.

In another preferable aspect, the control circuit outputs a timing signal that defines a start timing of the scanning period to the driving circuit, and outputs an output timing of the timing signal in a scanning period started by the timing signal. The display data stored in the memory is read out in synchronization with the control signal and the timing signal, adjusted for each scanning within a period until a predetermined time elapses after the end of the immediately preceding scanning period. And In this way, the relationship between the blinking timing of the light source and the position of the scanning line selected at this timing can be changed more irregularly.

In another preferable aspect, the control circuit outputs a timing signal that defines a start timing of the scanning period to the driving circuit, and outputs an output timing of the timing signal in a scanning period started by the timing signal. The display data stored in the memory is read in synchronism with the control signal and the timing signal at a predetermined time after the end of the immediately preceding scanning period. In this way, it is possible to output a timing signal with a fixed blanking period, and it is possible to easily adjust the start timing of the scanning period.

Note that 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 a projector having the electro-optical device.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment>
FIG. 1 is a plan view showing a configuration of a projector to which an electro-optical device according to an embodiment of the invention is applied. As shown in FIG. 1, a projector 2100 is provided with a lamp 2102 made of a white light source such as a halogen lamp driven by alternating current.

The projection light emitted from the lamp 2102 is composed of three mirrors 2106 disposed inside.
And two dichroic mirrors 2108, 3 for R (red), G (green), and B (blue).
The light is separated into primary colors and led to display panels 100R, 100G, and 100B corresponding to the primary colors. Note that the B-color light has an incident lens 2122, a relay lens 2123, and an exit lens 21 in order to prevent loss due to a long optical path compared to other R colors and G colors.
It is guided through a relay lens system 2121 comprising 24.

As will be described later, the display panels 100R, 100G, and 100B are each driven by display data corresponding to each color of R, G, and B, whereby a reduced image of each color is formed.
Reduced images formed by the display panels 100R, 100G, and 100B, that is, modulated light, enters the dichroic prism 2112 from three directions. In the dichroic prism 2112, the R and B light is refracted at 90 degrees,
G light 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 display panels 100R, 100G, and 100B include a dichroic mirror 21.
Since the light corresponding to the primary colors of R, G, and B is incident by 08, there is no need to provide a color filter. In addition, the transmission images of the display panels 100R and 100B are projected after being reflected by the dichroic prism 2112, whereas the transmission images of the display panel 100G are projected as they are, so that the reduced images formed by the display panels 100R and 100B. And the reduced image formed by the display panel 100G are in a horizontally reversed relationship.

Next, an electro-optical device with control of the display panels 100R, 100G, and 100B will be described.

FIG. 2 is a diagram illustrating a configuration of the electro-optical device 10. As shown in FIG. 2, the electro-optical device 1
0 includes a control circuit 12, a memory 13, display panels 100R, 100G, and 100B.
Among these, the display panels 100R, 100G, and 100B are driven by the drive circuits 14R, 14G, and 14B, respectively, corresponding to the primary colors of R, G, and B, respectively.

FIG. 3 is a diagram showing the configuration of the display panel 100R and the drive circuit 14R. In FIG. 3, the display panel 100R is described as an example, but the display panels 100R, 100G, 1
The configurations of 00B are the same. Therefore, the following description of the display panel 100R is similarly applied to the display panels 100G and 100B.
, 100B and the reduced image formed by the display panel 100G are in a horizontally reversed relationship as described above.

As shown in FIG. 3, in the display panel 100R, 1080 scanning lines 112 are arranged in the horizontal direction (X
The data lines 114 of 1920 columns are extended in the vertical direction (Y direction).
Each of the plurality of pixels 110 forming the reduced image has these scanning lines 112 and data lines 114.
Are arranged corresponding to each intersection. As described above, in the present embodiment, the pixels 110 are arranged in a matrix of 1080 vertical rows by 1920 horizontal columns, but the present invention is not limited to this arrangement, and the intersection of a plurality of scanning lines and a plurality of data lines. Any arrangement may be used as long as it is provided corresponding to.

The pixel 110 includes a liquid crystal element and a switching transistor (hereinafter referred to as a TFT) that is turned on or off between one end of the liquid crystal element and the data line. this house,
The liquid crystal element is a kind of capacitance in which liquid crystal is sandwiched between one end and the other end maintained at a constant potential, and has a transmittance according to the effective value of the holding voltage. The TFT is turned on when the scanning line 112 is selected and connects one end of the liquid crystal element to the data line 114.

The drive circuit 14R is divided into a Y driver 142 that drives the scanning line 112 and an X driver 144 that drives the data line 114. Of these, the Y driver 142 is 1, 2, 3,.
Scan signals Y1, Y2, Y3,..., Y1080 are supplied to the scan line 112 in the 1080th row.
Specifically, in this embodiment, the Y driver 142 sets the scanning line 112 to 1, 2, 3,.
In the order of the 80th row, the scanning signal to the selected scanning line is set to a level for turning on the TFT, and the scanning signal to the other scanning line is set to a level for turning off the TFT. This is controlled by a scanning control signal Cry output from the control circuit 12 described later. On the other hand, the X driver 144 sends a data signal X to the data line 114 in the 1, 2, 3,.
1, X2, X3,..., X1920 are supplied. Specifically, the X driver 144 outputs a voltage data signal corresponding to the gradation value of the pixel (the gradation value specified by the display data Dr) to the pixel 110 located on the selected scanning line 112. The data line 114 is supplied.

As a result, the liquid crystal element in the pixel holds a voltage corresponding to the gradation and has a transmittance corresponding to the holding voltage. In addition, since a liquid crystal may be deteriorated when a direct current component is applied, the drive of the liquid crystal element is basically an alternating current drive. Therefore, X driver 14
4 supplies the voltage of the data signal supplied to the same liquid crystal element by alternately switching the voltage at the other end of the liquid crystal element between the high-order side (positive polarity) and the low-order side (negative polarity).

Here, in the present embodiment, a period from when the scanning line 112 is sequentially selected from the first row to the 1080th row by the drive circuit 14R and the voltage is supplied to all the pixels 110 is referred to as the scanning period Fa. That's it. A period after the scanning period until the next scanning is started, that is, until the next scanning line 112 is selected is referred to as a blanking period Fb. Thereby, the period in one scanning is comprised by the scanning period Fa and the blanking period Fb.

Returning to FIG. 2, the description will be continued. The control circuit 12 controls the operation of each part of the electro-optical device 10. Specifically, the control circuit 12 receives a synchronization signal Sync from a higher-level device (not shown).
The display data Vd supplied in synchronization with is temporarily transferred to and stored in the memory 13, and then the display data Vd is read out from the memory 13 in synchronization with scanning of the display panels 100R, 100G, and 100B. Of the display data Vd, the control circuit 12 supplies the R component display data Dr to the drive circuit 14R, the G component display data Dg to the drive circuit 14G, and the B component display data Db to the drive circuit 14B. . The memory 13 is a FIFO (First-I
n First-Out) type memory.

Further, the control circuit 12 drives the drive circuits 14R and 14G so as to be synchronized with these supply operations.
, 14B are controlled by scanning control signals Cry, Cgy, Cby, respectively. The scanning control signals Cry, Cgy, and Cby are a timing signal DY that defines the start timing of the scanning period Fa, and a clock signal CL that is output from the control signal output circuit 15 described later.
Y is configured. The control circuit 12 performs control to change the frequency of the clock signal CLY output from the control signal output circuit 15 for each scan. Note that this frequency change may be performed for each of a plurality of scans.

The control signal output circuit 15 generates a clock signal CL having a frequency controlled by the control circuit 12.
Y is generated. The clock signal CLY is a control signal that defines the scanning period Fa by its frequency, as will be described below.

FIG. 4 shows the clock signal CLY and the scanning signals Y1, Y in the Y driver 142 described above.
2, Y3,..., Y1080. As shown in FIG. 4, the Y driver 14
2 generates scanning signals Y1, Y2,... According to the clock signal CLY, and scan line 1
12 are selected in the order of 1, 2, 3,. In the present embodiment, since two scanning lines 112 are sequentially selected during one cycle Tc of the clock signal CLY, the scanning period Fa, which is a period during which 1080 scanning lines 112 are selected, is 540 x Tc
It will be represented by Thus, the scanning period Fa is the period Tc of the clock signal CLY,
That is, it is defined by the frequency.

Therefore, when the frequency of the clock signal CLY is changed, the control circuit 12 changes the scanning period Fa.
Will be changed. Therefore, the control circuit 12 controls the drive circuits 14R, 14G, and 14B so as to change the scanning period Fa by changing the frequency of the clock signal CLY within a predetermined number range for each scan. Here, the predetermined number range may be, for example, a range in which the scanning period Fa does not exceed the period in one scan. In other words,
The control circuit 12 changes the frequency of the clock signal output from the control signal output circuit 15 so that the scanning period Fa started by the timing signal DY ends before the next timing signal DY is output. You can do it. That is, in the present embodiment, the control circuit 12 causes the clock signal CL so that 540 × Tc is shorter than the period in one scan.
The frequency of Y may be controlled. Although the lower limit of the frequency is determined by this, the upper limit may be determined or may not be determined. In the case of determination, for example, since the selection period of one scanning line is shortened, the period in which a voltage corresponding to the gradation value can be sufficiently supplied to each pixel and the period in which the voltage can be held are determined. The upper limit of the frequency may be determined. That is, it is good also as an upper limit of the frequency according to the characteristic of TFT of each pixel. Further, an appropriate frequency may be set in advance as an upper limit and a lower limit.

Returning to FIG. 2, the description will be continued. The lighting circuit 20 drives the lamp 2102 with alternating current by outputting a drive signal Fla having a predetermined frequency. Here, when the polarity of the drive signal Fla is switched, the pulse shape of the drive signal Fla is adjusted (not shown) in order to increase the life of the lamp 2102. As a result, the lamp 2102 repeats blinking at twice the frequency of the drive signal Fla because the amount of light increases immediately after the polarity is switched.

Next, the display data Vd described above will be described. The display data Vd is supplied at a constant supply speed in synchronization with the synchronization signal Sync supplied at a constant cycle. The display data Vd is
As shown in FIG. 5, the period f of one frame includes an input scanning period fa and an input blanking period fb. In this input scanning period fa, the display data Vd is from 1 row 1 column to
1 row 1920 column, 2 rows 1 column to 2 rows 1920 columns, 3 rows 1 column to 3 rows 1920 columns, ..., 1080
The pixels are supplied in the order of pixels of row 1 column to 1080 row 1920 column. On the other hand, the input blanking period fb
In this case, nothing is supplied as the display data Vd. The same applies to the next frame, and this supply is repeated thereafter.

Next, for each operation of the operation of the electro-optical device 10 according to this embodiment, the clock signal CL
Compared to the prior art in which the frequency of Y is not changed, a description will be given with reference to FIGS.

FIG. 6 is a diagram showing the relationship of operation between the lamp 2102 and the display panel 100 in the prior art. The horizontal axis of FIG. 6 shows the progress of time. In the prior art, as shown in FIG. 6, a synchronization signal Sync is supplied in synchronization with the display data Vd. And the drive circuit 14R,
14G and 14B are supplied in synchronization with the scanning control signals Cry, Cgy and Cby, in which the display data Dr, Dg and Db are composed of the timing signal DY and the clock signal CLY. Driving is performed so that the scanning period becomes the scanning period Fa and the blanking period Fb. At this time, the input scanning period fa related to the display data Vd
The clock signal CLY is controlled so that the scanning period Fa is the same time. Further, since the timing signal DY is output in the same cycle as the synchronization signal Sync without adjusting its output timing, the input blanking period fb and the blanking period Fb related to the display data Vd are the same time. . Q1, Q2,... Indicate display data corresponding to each scan.

Here, the timing at which the polarity of the drive signal Fla switches within the scanning period of each scan is such that the relative relationship within that scanning period is shifted by a certain amount for each scan, as indicated by the dashed arrows in the figure. To go. As a result, the timing at which the light amount of the lamp 2102 increases and the position of the scanning line selected at that timing are gradually shifted and recognized as scroll noise. At this time, the closer the relationship between the period of one scan and the period of an integral multiple of the period corresponding to half of the drive signal Fla is, the easier it is to be visually recognized because the relative relationship shifts slowly. The effect of scroll noise is increased.

FIG. 7 is a diagram illustrating the relationship between the operation of the lamp 2102 and the display panel 100 of the electro-optical device 10 according to this embodiment. The horizontal axis in FIG. 7 indicates the progress of time. Q1, Q2,
... Shows display data corresponding to each scan as in FIG. At this time, when the display data Vd for one frame can be stored in the memory 13 and the display data Vd corresponding to Q2 is supplied to the memory 13, the display data Dr, Dg, D corresponding to Q1.
b is read from the memory 13.

As described above, the control circuit 12 changes the scanning period Fa by changing the frequency of the clock signal CLY for each scan. In the present embodiment, when changing the frequency of the clock signal CLY, the control circuit 12 changes the frequency from a predetermined number range to a randomly selected frequency. The drive circuits 14R, 14G, and 14B are provided with scanning control signals Cry, which are composed of the timing signal DY and the clock signal CLY output in this way.
Display data Dr, Dg, Db is supplied in synchronization with Cgy, Cby, and the display panel 100
A period in one scanning in R, 100G, and 100B is a scanning period Fa (Fa0, Fa
1, Fa2,...) And a blanking period Fb (Fb0, Fb1, Fb2,...).

Here, since the output timing of the timing signal DY is not adjusted and the sync signal Sync is output at a constant cycle, the period of one scanning, that is, the scanning period Fa and the blanking period Fb The total duration does not change. That is, when the frequency of the clock signal CLY is changed by the control circuit 12, the scanning period Fa is changed for each scanning, and accordingly, the blanking period Fb is also changed.

Here, the timing at which the polarity of the drive signal Fla switches within the scanning period Fa of each scan is irregular for each scan, as indicated by the dashed arrows in the figure, in the relative relationship within the scanning period Fa. To change. As a result, even when the light amount of the lamp 2102 increases and the position of the scanning line selected at that timing changes, this shift mode is irregularly changed, so that it is not recognized as scroll noise.

As described above, in the electro-optical device 10 according to the present embodiment, the clock signal C is scanned for each scan.
Since the scanning period Fa is changed by changing the frequency of LY, the occurrence of scroll noise can be suppressed without changing the driving frequency of the light source. Therefore, even if the lamp 2102 using the drive signal Fla of any drive frequency is used, the generation of scroll noise can be suppressed.

As mentioned above, although embodiment of this invention was described, this invention can be implemented in various aspects as follows.

<Modification 1>
In the above-described embodiment, the timing signal DY is output at a constant period. However, the control circuit 12 may adjust the output timing of the timing signal DY for each scan. The adjustment of the output timing may be performed, for example, so as to be a timing selected at random within a period until a predetermined time elapses after the end of the scanning period immediately before the scanning period started by the timing signal DY. The predetermined time can be various times. For example, the display data Vd stored in the memory 13 is stored in the memory 1.
What is necessary is just the time until 3 reaches the amount of data that can be stored.

FIG. 8 is a diagram illustrating the relationship between the operation of the lamp 2102 and the display panel 100 of the electro-optical device 10 according to this modification. In FIG. 8, Q1 is compared with FIG. 7 in the description of the embodiment.
The output timing of the timing signal DY that defines the start timing of the scanning periods Fa1 and Fa3 related to Q3 and Q3 is adjusted to a later timing, while the scanning period Fa2 related to Q2 and Q4 is adjusted.
The output timing of the timing signal DY that defines the start timing of Fa4 is shown when adjusted to the previous timing.

In this way, since the start timing of each scanning period Fa can also be changed, the timing at which the amount of light of the lamp 2102 becomes larger than the case where the start timing is not changed, and the scanning line selected at that timing. The irregularity of the mode of deviation when the position changes for each scan becomes larger, and the generation of scroll noise can be further suppressed. In particular, among the scanning lines selected at the timing when the amount of light of the lamp 2102 increases, the scanning line corresponding to the first part of the scanning period Fa has a large irregularity in the position change, and thus the display panel 100. The effect of removing the scroll noise in the upper part can be made large.

<Modification 2>
In the embodiment described above, the control circuit 12 changes the frequency of the clock signal CLY to a frequency randomly selected from a predetermined number range in order to change the scanning period Fa for each scan. May be. For example, the control circuit 12 defines candidate frequencies, stores a plurality of these frequencies, and selects the candidate frequencies randomly or by a predetermined algorithm for each scan, and changes the frequency of the clock signal CLY. You may do it.
Note that the predetermined algorithm may be any algorithm as long as it prescribes the order of frequencies to be selected for each scan.

In the first modification described above, the control circuit 12 randomly selects the adjustment of the output timing within a period until a predetermined time elapses after the end of the scanning period immediately before the scanning period started by the timing signal DY. However, it may not be random. For example, the timing at which the control circuit 12 becomes a candidate is defined as an adjustment time from the end of the scanning period until the timing signal is output, a plurality of adjustment times are stored, and the candidate adjustment time is randomly determined for each scan. Or select with a predetermined algorithm,
The timing signal DY may be output corresponding to the adjustment time. Note that the predetermined algorithm may be any algorithm as long as it defines the order of adjustment times to be selected for each scan.

<Modification 3>
In the first modification described above, the timing signal D is set so that the blanking period Fb is constant.
The Y output timing may be defined. In this case, the control circuit 12 may set the output timing of the timing signal DY to a timing after a predetermined time from the end of the scanning period immediately before the scanning period started by the timing signal DY.

In the embodiment, since the timing signal DY is output at a constant period, the period in one scan is constant, and even if the scan period Fa is changed in each scan, the scan period Fa and the blanking period in one scan Although the total period of Fb was constant, in this way, the control circuit 1
Second, by adjusting the output timing of the timing signal DY, the blanking period Fb may be constant in each scan, and the period in one scan may be changed for each scan. The blanking period Fb in each scan and the period in one scan may be changed. That is, the control circuit 12 may determine the blanking period Fb and the period in one scan in any manner as long as the scan period Fa is changed for each scan by changing the frequency of the clock signal CLY.

<Modification 4>
In the embodiment described above, the electro-optical device 10 includes the display panels 100R, 100G,
Although 100B uses a transmissive liquid crystal panel, it may be a reflective type. Also,
In the embodiment described above, the case where the electro-optical device 10 is applied to a projector has been described. However, the electro-optical device 10 may be used for a direct-view display having a backlight which is an AC-driven light source.

It is a top view which shows the structure of the projector which concerns on embodiment of this invention. 1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment of the invention. FIG. It is a figure which shows the structure of the display panel which concerns on embodiment of this invention. It is a figure which shows the relationship between the clock signal which concerns on embodiment of this invention, and a scanning signal. It is a figure which shows the display data which concern on embodiment of this invention. It is a figure which shows operation | movement of the conventional electro-optical apparatus. FIG. 6 is a diagram illustrating an operation of the electro-optical device according to the embodiment of the invention. FIG. 10 is a diagram illustrating an operation of the electro-optical device according to the first modification of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electro-optical apparatus, 12 ... Control circuit, 13 ... Memory, 14R, 14G, 14B ... Drive circuit, 15 ... Control signal output circuit, 20 ... Lighting circuit, 100R, 100G, 100B ... Display panel, 110 ... Pixel, 2100 …projector

Claims (6)

A display panel having a plurality of pixels and irradiating light to a light source driven by alternating current;
A memory for accumulating display data to be supplied and reading the display data;
A control signal output circuit for outputting a control signal of a predetermined frequency;
The display data read from the memory is supplied, and in each scan, the period for driving the plurality of pixels according to the display data is a scan period according to the frequency of the control signal. A driving circuit for scanning and driving the display panel;
The drive circuit is controlled to change the scanning period by changing the frequency of the control signal output from the control signal output circuit within a predetermined number range for each of one or a plurality of scans, and the control And a control circuit that reads display data stored in the memory in synchronization with a signal and supplies the display data to the driving circuit. The control circuit includes:
A timing signal that defines the start timing of the scanning period is output to the driving circuit at a constant period,
The electro-optical device according to claim 1, wherein the display data stored in the memory is read in synchronization with the control signal and the timing signal. The control circuit includes:
Outputting a timing signal defining the start timing of the scanning period to the drive circuit;
The output timing of the timing signal is adjusted for each scan within a period until a predetermined time elapses after the end of the scanning period immediately before the scanning period started by the timing signal,
The electro-optical device according to claim 1, wherein the display data stored in the memory is read in synchronization with the control signal and the timing signal. The control circuit includes:
Outputting a timing signal defining the start timing of the scanning period to the drive circuit;
The output timing of the timing signal is a timing after a predetermined time after the end of the scanning period immediately before the scanning period started by the timing signal,
The electro-optical device according to claim 1, wherein the display data stored in the memory is read in synchronization with the control signal and the timing signal. An electro-optical device according to any one of claims 1 to 4,
A projector comprising: a projection lens that projects modulated light obtained by irradiating the display panel with light emitted from the light source. A driving method of an electro-optical device including a display panel having a plurality of pixels and irradiated with light to a light source that is AC driven,
Output a control signal of a predetermined frequency,
After storing the supplied display data in the memory, the display data is read at a predetermined timing,
In each scan, the display panel is scanned and driven so that a period during which the plurality of pixels are driven according to display data read from the memory is a scan period according to the frequency of the control signal. And
Controlling the drive of the display panel to change the scanning period by changing the frequency of the control signal within a predetermined number of ranges for every one or a plurality of scans;
The timing for reading the display data stored in the memory is synchronized with the control signal.

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