JPH03271795A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce electric power consumption and to suppress stripe-shaped disturbances to an inconspicuous level as well as to allow flickerless AC driving by setting the polauty inversion period of an image signal voltage to the time for driving address lines successively by every other piece or every other plural pieces down to the bottom end of a screen. CONSTITUTION:An interlace control circuit 110 controls an address line driving circuit 17 and drives the address lines of a liquid crystal panel 10 successively by every other piece or every other plural pieces down to the bottom end of the screen, then repeats the operation of to the top end of the screen and driving every other piece or every other plural pieces. The signal lines are driven by the image signal voltages, inverts the polarity at every time when the driving circuit 17 drives the address lines down to the battom end of the screen and subjects to the polarity inversion by every one or every plural pieces thereof. The stripe-shaped disturbances in the frame are suppressed down to the inconspicuous level in this way and the flickerless AC driving is possible while the increase in the electric power consumption is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a liquid crystal display device, and particularly to a drive circuit for driving a liquid crystal panel.

(Prior Art) Generally, a liquid crystal display device (TPT-LCD) using a thin film transistor (TPT) in a drive circuit is configured as shown in FIG. In FIG. 16, the liquid crystal panel 10
is a plurality of address lines 11 along the horizontal scanning direction, a plurality of signal lines 12 along the vertical scanning direction, and a liquid crystal display element connected to each intersection of these address lines 11 and signal lines 12. (referred to as pixels) 13.

The pixels 13 each include a liquid crystal cell 14 and a thin film transistor (
TPT) 15 and a capacitor 16 for charge retention. An address line drive circuit 17 is connected to the address line 11, and a signal line drive circuit 18 is connected to the signal line 12. The address line drive circuit 17 is a circuit that sequentially drives the address lines 11 one by one, and the signal line drive circuit 18 is a circuit that drives the signal lines 12 simultaneously in accordance with image signals.

Figure 17 is an equivalent circuit for one pixel in Figure 16.
FIG. 8 shows the waveforms of the image signal voltage VSI that drives the signal line 12, the gate voltage Vgn that drives the address line 11, and the pixel voltage V that is applied to the liquid crystal cell 14.

First, the image signal voltage VSI is applied only to the liquid crystal cell 14 of the pixel selected for each field by the gate voltage Vgn, thereby changing the pixel potential (2). At this time, TFT15
On-current I flowing through.

is ID −Cox・u (W/L)(Vo −V
ss) fVgn-Vth-(Vo +Vsm)/21
(1) It is expressed as. Here, Cox: gate insulating film (oxide film) capacitance of the TFT 15, μ: mobility, V th: threshold voltage, W: channel width of the TFT 15, and L: channel length of the TFT 15.

In a liquid crystal display device, if a voltage with a constant polarity is applied to a liquid crystal cell, a DC component will accumulate and the liquid crystal cell will be burned out.
As shown in Figure (a), a method is used in which the image signal voltage Vss is inverted for each field. When such AC driving is performed, as is clear from equation (1), the image signal voltage V
When SI is positive, the on-state current is smaller than when it is negative, so asymmetry occurs during positive and negative driving as shown in FIG. 18(C), which may cause flicker. This is because the liquid crystal reacts with the effective value of the applied voltage, so the pixel potential Vp is folded back at the common electrode potential Vcow of the liquid crystal panel 1o.
This is because the transmittance (ultimately, the brightness) of the liquid crystal varies from field to field because the difference in each field differs from field to field.

Furthermore, as is clear from FIG. 17, the pixel potential VD leaks through the parasitic capacitance Cgd between the gate and drain of the TFT 15 at the moment the gate voltage Vgn is turned off, and drops by the amount. However, Cds: the drain of TFT15
Source-to-source parasitic capacitance, C8: Capacitance of the polarizer 16, Ct
c: fi crystal capacitance, Cpd: parasitic capacitance between the signal line 11 and the drain of the TFT 15. This potential change also appears in the field period, resulting in flicker.

In addition to the two factors mentioned above, there are other factors contributing to flicker.
There is an off-state current of FT15. This is because the off-state current of the TFT 15 changes depending on the gate-source voltage Vgs, that is, it differs depending on whether the pixel potential VD is positive or negative.
As shown in Figure 13(c), (△v opp −△V
This appears as a field flicker with a luminance change corresponding to (opp-).

In summary, the causes of flicker in a TFT-LCD include: (1) Insufficient on-current of the TPT; (2) Leakage of gate voltage due to capacitance between the gate and drain of the TPT; (2) Off-current of the TPT.

As described above, because the characteristics of the TFT 15, which is a switching element of the liquid crystal panel 10, are insufficient, the effective voltage applied to the pixel varies depending on the polarity of the image signal voltage, and as a result,
When normal field inversion driving as shown in FIG. 19(a) is performed, a surface flicker of 80 Hz appears. As a method of reducing this surface flicker, a method of inverting the image signal voltage within a frame has been proposed. That is, it attempts to visually reduce the amount of flicker by converting surface flicker into line flicker or minute surface flicker (for example, pixel flicker). A known example of flickerless drive using this method is shown in Figure 19(b).
Shown in (c). FIG. 19(b) shows a line inversion method in which the image signal voltage is inverted for each horizontal scanning line, and by performing inversion driving not only within a frame but also between frames, alternating current driving for each pixel is realized. Also, Fig. 19(C)
In this method, the polarity of the image signal voltage is inverted for each signal line 11 or each pixel 13 (for each dot), and inversion is performed between frames in the same way as line inversion, thereby converting surface flicker into flicker for each signal line. According to the intra-frame inversion methods represented by these three methods, line inversion, signal line inversion, and dot inversion, since the brightness is balanced in each frame, surface flicker in each frame is reduced not only theoretically but also visually. below the detection limit.

However, in the intra-frame reversal method, movement occurs on the screen due to panning of the video camera, and visual disturbance occurs when the movement is followed with the eye. For example, in line reversal, the visual movement in the vertical direction has a velocity Ve Ve = (2n+ 1) fl Y /Tf'
(3) However, if the pixel pitch in the 1y and 2 vertical directions is n: o, 1.2... Tf: field period, this speed is exactly the same as the moving speed of the horizontal stripes caused by positive/negative reversal driving within the frame. Because they match, the horizontal stripes within the frame appear to be stationary. the result,
Horizontal stripes are clearly perceived on the screen, and on the contrary, they become a major hindrance.

Regarding the signal line inversion and dot inversion in FIG. 14(C), there is almost no fundamental difference except that the horizontal stripes are changed to vertical stripes.

Figure 20 shows the contrast discrimination threshold of human vision.
This shows the results of an investigation by Mr. Hiwatari et al. of HK. It can be seen that the maximum sensitivity point exists at spatial frequencies 2 to 3 [cpd], and the bandpass characteristics can be discriminated with a contrast of 0.005, and that the higher the spatial frequency is, the harder it is to see. From this, it is possible to compare the disturbance sensation caused by horizontal stripes and vertical stripes using spatial frequency, which is one parameter of visual characteristics. Considering the condition that the screen is viewed from three times the screen height H, that is, from 3H, the spatial frequencies of horizontal stripes and vertical stripes are as follows.

In line inversion, however, Nv: Number of vertical scanning lines fLN: Spatial frequency of horizontal stripes If Nv = 488, then f LN-12,8 [cpd] In signal line inversion and dot inversion, however, NH: Number of horizontal pixels fspt: From the spatial frequency equations (4) and (5) for vertical stripes, the relationship between the number of pixels and the spatial frequencies of vertical stripes and horizontal stripes is as shown in FIG. However, when performing the above calculations, we confirmed through experiments that horizontal and vertical stripes occur at the pitch shown in Figure 22 depending on the drive method, since the visual sense has maximum sensitivity near green. used. As can be seen from FIG. 22, in the signal line inversion method and the dot inversion method, the pitch of vertical stripes is larger and easier to see than in the line inversion method. This is especially true when the color filter array is a delta array, as shown in Figure 22, the image signal voltage of the G (green) pixel is 2.
This is because unnecessary pitches occur because every other piece is inverted.

From the above, it can be said that the line inversion method is currently less visually noticeable, but the line inversion method has the problem of increased power consumption. The power consumption P is the drive frequency fDs, the amplitude of the image signal voltage input is vp-p
, the power supply voltage is given by the following equation, where the capacitance of the capacitor for holding VD% is C.

P=Vn-fo' C・Vp-p (6) Therefore, power consumption changes depending on how the input changes, but since the correlation between images is high, consider the case where the voltage of human power is almost constant. .

I) Field inversion, signal line inversion Since the input frequency fD is 172 times the field frequency fv, the power consumption P PR + P SR in field inversion and signal line inversion is p , Rwm p S
il v -V, ・-・C-Vp-p (7)1
1) Since the line inversion and dot inversion input frequency is the horizontal frequency fH, the power consumption in line inversion and dot inversion is PLR+PDR
N is PLR″″PDRN-■. -f, -C·v p-p = 525PFR (8) Thus, it can be seen that the line inversion method requires several hundred times as much power consumption as the signal line inversion method.

(Problems to be Solved by the Invention) As described above, as a flicker-free AC drive method for conventional liquid crystal display devices, methods using polarity inversion drive within a frame such as signal line inversion, dot inversion, and line inversion are known. However, the signal line inversion method and the dot inversion method cause striped interference within the frame, and while the line inversion method causes less interference, it has the problem of increased power consumption.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can realize flicker-free AC driving while making striped interference in a frame less noticeable and minimizing an increase in power consumption.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the liquid crystal display device of the present invention has the following features:
A first driving means that repeats the operation of sequentially driving every other address line or every plurality of address lines in the liquid crystal panel to the bottom edge of the screen, and after driving the address lines to the bottom edge of the screen, returns to the top edge of the screen and drives every one or more lines. and a first driving means that drives the signal lines in the liquid crystal panel with an image signal voltage whose polarity is inverted every time the first driving means drives the address line to the bottom edge of the screen, and whose polarity is inverted for each signal line or every plurality of signal lines. It has two driving means.

In addition, in a liquid crystal display device according to another aspect of the present invention, a display screen formed by a liquid crystal panel is virtually divided into a plurality of blocks, and address lines are sequentially arranged every other block or every plurality of blocks in each block. A first driving means repeats the operation of driving the signal line to the bottom end, driving it to the bottom end of the block, returning to the top end of the block, and driving every other line or every plurality of address lines. It has a second driving means that is driven by an image signal voltage whose polarity is inverted every time it is driven to the bottom end of the block, or by an image signal voltage whose polarity is inverted for each one or a plurality of signal lines.

(Function) In the present invention, the polarity of the image signal voltage is reversed within the frame, and flicker-free AC driving is realized. The polarity inversion period of the image signal voltage in the present invention is the time required to sequentially drive every other address line or every other address line to the bottom of the screen, and is longer than the polarity inversion period of the image signal voltage in the line inversion method. Therefore, power consumption is reduced. Moreover, the striped disturbances occurring within the frame become visually inconspicuous because they become diagonal stripes or dots.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a liquid crystal TV to which a liquid crystal display device according to an embodiment of the present invention is applied.

In FIG. 1, an NTSC video signal, for example, is input to an input terminal 100. This input video signal is split into two, one of which is input to an A/D converter 101 and digitized. The other of the two-branched input video signal is PL
The signal is input to the L circuit 108, and a reference clock signal synchronized with the input video signal is generated. Based on this reference clock signal, timing control circuit 109 generates timing signals necessary for controlling each part.

The video signal digitized by the A/D converter 101 is first converted into a luminance signal (Y/C) by the Y/C separation circuit 102.
signal) and a color difference signal (C signal). The output of the Y/C separation circuit 102 is an interlace signal according to the NTSC system, and is converted into a non-interlace signal by the double speed conversion circuit 103. The double speed conversion circuit 103 interpolates the interlaced signal and increases the horizontal scanning frequency to 15
．． An operation of converting from 73 kHz to 31.47 kHz, so-called double speed conversion, is performed. The double-speed converted luminance signal and color difference signal are converted into RGB signals by the RGB conversion circuit 104 and then input to the order conversion circuit 105.

The order conversion circuit 105 changes the RGB of each scanning line in response to the address lines of the liquid crystal panel 10 being driven every other or every other address line (in this example, every second or third address line). Swap the signals. This order conversion circuit 1
05 is specifically configured using, for example, three frame memories, and after temporarily storing the input KGB signals in each frame memory under the control of the timing control circuit 109, the position of the address line to be driven (scanning line ), the order-converted RGB signals are output.

The RGB signals thus order-converted are sent to the D/A converter 1.
06, the signal is returned to an analog signal, and further amplified to an appropriate level by a polarity inverting amplifier 107 for AC drive, and then supplied to the signal line drive circuit 18. The signal line drive circuit 18 is composed of, for example, first and second integrated circuits that are arranged separately on both the upper and lower sides of the liquid crystal panel 1o in the figure, and the first integrated circuit is arranged, for example, at an odd-numbered integrated circuit as counted from the starting end in the horizontal scanning direction. The second integrated circuit drives the even-numbered signal lines. In this case, the polarity of the image signal voltage applied to the signal line driven by the first integrated circuit and the polarity of the image signal voltage applied to the signal line driven by the second integrated circuit are always opposite in polarity. The polarity inversion amplifier 107 is controlled by a timing control circuit 109.

On the other hand, the 3:1 interlace control circuit 110 controls the address line drive circuit 11 so that every three address lines of the liquid crystal panel 10 are sequentially driven.

Next, the operation of this embodiment will be explained.

As explained in the above-mentioned section on the prior art, there are three main factors that can cause flicker, and the largest factor among them is the off-state current. Therefore, Tadashi
Regarding the case where different off-state currents occur with negative polarity,
Let's consider it in a little more detail. First, (1) The off-state current varies depending on the polarity, but is constant.

(2) The response speed of the liquid crystal is not considered.

Assume the following conditions. Assumption (2) is considered valid since it is sufficient to finally multiply the response characteristics.

At this time, the transmission characteristic 1(t) (luminance characteristic) of the liquid crystal panel 1o, that is, the temporal change in flicker, can be expressed as shown in FIG. 2(a). This can be expressed numerically as follows.

If we expand this into a Fourier, we get (VN Vp ) sinkt + (1+(-1
)' )(VN +VP)coskt
(10) Here, 30Hz is important for flicker.
Considering only the components, k-1, that is, each pixel has a spectrum pio as a flicker component as shown in FIG. 2(b).

As a method to remove this flicker component, ■Brightness change i(t) itself becomes a high frequency.

■Compensate using adjacent pixels.

Methods such as the following can be considered, but at present, method (2) is often used due to problems such as high speed driving with method (2). The line inversion, signal line inversion, and dot inversion methods described in the prior art section are typical examples of the method (2). Here, method (2) will be explained in more detail.

First, in any method, signals of opposite polarity are input to adjacent pixels, so the average luminance i a(t) of two pixels is expressed by the following equation.

ω. −π/Tf When this is Fourier transformed, I a(ω) −I o(ω)(l −e “””)(
13) It becomes.

Therefore, Ia(ω.)-0, and the flicker component can be completely compensated for.

The above is a case in which flicker components are compensated for and removed by two adjacent pixels, but this can generally be considered by expanding the number of adjacent pixels that are mutually compensated to N pixels. At this time, the average brightness i of adjacent N pixels
a(t) and its Fourier transform 1a(ω) are:

The following description will take an example of a case where flicker components are compensated for using three pixels. In Fig. 3, the time change i (t) of the transmittance of each of the three pixels obtained from equation (14) is shown as a solid line, - a dashed line,
The dotted line indicates the overall transmittance change at this time i a(t)
It was shown as Moreover, the frequency spectrum is shown in FIG. As is clear from FIG. 3, if the transmittance changes i (t) of mutually compensated pixels are the same, originally 2Tf'
(Tf: field period - 1/60 seconds), the flicker component was reduced to 2Tf/3, that is, 1/60 seconds, by three-pixel compensation.
It is possible to set the cycle to 3. Looking at the frequency spectrum, this means that each pixel is π/Tf relative to each other, as shown in Figure 4.
, 2π/Tf components are compensated for each other.

In this embodiment, the above principle is used to sequentially drive every third address line (every second line), that is, every third line, as shown in FIG. In other words, one field period Tf is set to 3
Divide it into two periods, and in the first T'/3 period, extend the address line from the top of the screen to 1.4...N, N+3.N+6...
It is driven every three lines. After driving to the bottom of the screen in this way, it returns to the top of the screen in the next Tf/3 period, and shifts the address line by one line from the first Tf/3 period by 2, 5. ...N+1. N+4°N+7.・・・
・Similarly drive every 3 lines to the bottom edge of the screen. After that, in the final Tf /3 period, return to the top of the screen again and change the address line to 3.6. ...N+2. N+5
．． N+8. ... Drive every 3 lines to the bottom of the screen. This constitutes one field.

In this case, in the first field, the polarity of the image signal voltage applied to the signal line is positive in the first Tf /3 period, negative in the next Tf /3 period, and positive in the last Tf /3 period. In the next second field, if an image signal voltage with the opposite polarity is applied to the signal line, each pixel will be driven by alternating current with field inversion.
The DC component does not accumulate. In addition, the polarity inversion period of the image signal voltage is 1/3 field period (Tf/3), which is much longer than one horizontal scanning period (IH) of the line inversion method, which is advantageous in terms of power consumption. becomes.

However, when such driving is performed, although flicker is eliminated, horizontal stripes within the frame become more noticeable than in the line inversion method. For example, if the liquid crystal panel 10 is a color panel and its color filter arrangement is a delta arrangement as shown in FIG. Horizontal stripes occur. The pitch of these horizontal stripes is 1.5 times that of line inversion, making it easier to see.

Therefore, in this embodiment, the polarity of the image signal voltage is also inverted in the signal line direction so that such horizontal stripes become less noticeable. In this case, the horizontal stripes are converted into a zigzag pattern of diagonal stripes as shown in FIG.

FIG. 10 and FIG. 11 show how pixels are driven in the first field and the second field in this embodiment.

That is, the initial Tf'/3 in the first field
During the period, as shown in FIG. 10(a), 1.4. ...
N, N+3. N+5. . . . While driving the address line of the line, a positive image signal voltage is applied to the odd-numbered signal lines, and a negative image signal voltage is applied to the even-numbered signal lines.

In the next Tf /3 period, 2, 5... as shown in FIG. 10(b). ...N+1. N+4. N+7. . . . While driving the address line of the line, a negative image signal voltage is applied to the odd-numbered signal lines, and a positive image signal voltage is applied to the even-numbered signal lines. In the final Tf /3 period, as shown in FIG. 10(c), 3.6. -N+2
．． N+5°N+8. . . . In addition to driving the address line of the line, as in the first Tf/3 period, a positive image signal voltage is applied to the odd-numbered signal lines, and a negative image signal voltage is applied to the even-numbered signal lines. Apply.

In the second field, similar driving is performed by reversing the polarity of the image signal voltage from the first field. That is, in the first T'/3 period in the second field, as shown in FIG. 11(a), 1.4...N, N+3.
N+6.・・・While driving the address line of the line,
An image signal voltage of negative polarity is applied to the odd-numbered signal lines, and an image signal voltage of positive polarity is applied to the even-numbered signal lines. In the next Tf /3 period, as shown in FIG. 11(b), 2.5. ...N+1. N+4°N+7. . . . While driving the address line of the line, a positive image signal voltage is applied to the odd-numbered signal lines, and a negative image signal voltage is applied to the even-numbered signal lines. In the last T'/3 period, as shown in Fig. 11(C), 3,6°...N
+2. N+5. N+8. . . . In addition to driving the address line of the line, as in the first Tf/3 period, a negative image signal voltage is applied to the odd-numbered signal lines, and a positive image signal voltage is applied to the even-numbered signal lines. Apply.

Such driving is achieved by, for example, controlling the address line driving circuit 18 so that the address lines are driven as described above by the 3:1 interlace control circuit 110 in FIG. 1, and also controlling the signal line driving circuit 18. By controlling the polarity inverting amplifier 107 so that the polarity of the image signal voltage applied to the odd-numbered and even-numbered signal lines from the first and second integrated circuits, respectively, is inverted every Tf /3 period. It can be realized.

When driving according to the present embodiment as described above, a positive polarity image signal voltage was applied which increases the transmittance (brightness) of the liquid crystal among the green (G) pixels, which have high visibility for humans. Considering that the 0 pixel is visually the most conspicuous, diagonal stripes as shown in FIG. 9 will occur in a liquid crystal panel having a delta color filter arrangement as shown in FIG. 7. The shaded area in FIG. 9 indicates the position of the 0 pixel to which a positive image signal voltage was applied in the driving process described using FIGS. 10 and 11.

Since human visual characteristics are less sensitive to diagonal directions by about 6 dB, diagonal stripes as shown in FIG. 9 are less visually noticeable than horizontal or vertical stripes. Moreover, since this diagonal stripe pattern moves diagonally at a speed of 3/Tr, it becomes more difficult to detect. Furthermore, since this driving method compensates for the brightness from the left, right, top and bottom of the pixel, it is possible to compensate for inputs (for example, vertical stripes, horizontal stripes) that cannot be compensated for only from the top and bottom or from the left and right.

Furthermore, according to this embodiment, lower power consumption is achieved.

That is, the power consumption P when compensation is performed using adjacent (2n+1) pixels as in this embodiment is as follows, and it can be seen that the power consumption P is considerably reduced compared to line inversion.

Next, other embodiments of the present invention will be described.

In the previous embodiment, 30Hz flicker was completely compensated for, but in reality, the DC component is compensated for by 140Hz.
If it's around dB, you can't see it. An example of flickerless driving using this will be described with reference to the following embodiment.

In this embodiment, first, a display screen made up of the liquid crystal panel 10 is virtually divided into a plurality of blocks. As a method of dividing the display screen into blocks, it may be divided into upper and lower blocks (in the vertical scanning direction) as shown in FIG.
The image may be divided horizontally (in the horizontal scanning direction) as shown in FIG. 12(b), or vertically and horizontally as shown in FIG. 12 <C>.

Then, for each block, for example, as shown in FIG. 13, address lines are connected N from the top of the block.

N+2. N+4. ...The lines (indicated by solid arrows) are driven every other line (every second line) sequentially to the bottom of the block, and a positive image signal voltage is applied to all signal lines, and then from the top of the block N+1. N+3. N+5.
. . . Address lines (indicated by broken arrows) are sequentially driven to the bottom end of the block, and negative image signal voltages are applied to all signal lines.

After one field of screen is constructed in this way, the next field is driven with a signal of opposite polarity. Let us consider the influence that such driving has on flicker.

Now, the time difference until the polarity of the image signal voltage changes from positive polarity to negative polarity within each block (for example, 1, 3...
N, N+2. N+4. . . . After the start of driving the address line of the line to the bottom end of the block, N+1. N+3
．． N+5. ...time until the start of driving the address line of the line) τ. Then, the average brightness spectrum of two pixels adjacent in the vertical scanning direction is as shown in FIG. Actually τ. The direction of the component indicated by the broken line arrow changes depending on the magnitude of , and the improvement rate of the most conspicuous π/Tf component changes. Therefore, τ0 or the number of lines in the block N, and π/T
Let's find the relationship with the f flicker component.

Letting θ be the angle between the π/Tf flicker component F30 for compensation as shown in FIG. 60r l) 1 Number of lines in the block N and flicker improvement rate R calculated from the above formula
FIG. 15 shows the relationship between From FIG. 15, if it is desired to improve the flicker by about 10 dB, for example, the screen can be divided into blocks and driven such that 200 lines are in one block, that is, 215 lines on the display screen are in one block.

In addition, the power consumption PB at this time is determined by the drive frequency f (where N is the number of lines in the block) and the 30Hz fritz force component in the case of field inversion, F N
ot, then F 3ot -2F 3on Therefore, the improvement rate R is as follows: PB =Vo -fs -C*Vp-p25 1■.・-fv'c ・v p-p-P LR pot -(21) Even in the drive as in the second embodiment, if the horizontal stripes in the frame are noticeable, A method of inverting the polarity of the image signal voltage may also be used. That is, in the above embodiment, one address line is provided for each block.
Drive every other block sequentially to the bottom end of the block, then return to the top end of the block and repeat the operation of driving every other block, and apply voltage to the signal line every time the address line is driven to the bottom end of each block. The polarity of the image signal voltage may be inverted, or in addition, when driving the signal lines, an image signal voltage with inverted polarity may be applied to each signal line or to each plurality of signal lines. As a result, the striped interference becomes diagonal stripes or dots as in the previous embodiment, and the sense of interference is further reduced.

In this embodiment, every other address line is sequentially driven, but it is also possible to drive every other two or more address lines.

[Effects of the Invention] According to the present invention, it is possible to reduce the striped interference occurring within the frame while performing flickerless driving, and the power consumption is only slightly higher than before performing flickerless driving. It has the advantage of being much smaller than the line inversion method.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a diagram showing the temporal change and spectrum of flicker to explain the principle of the embodiment, and FIG. FIG. 4 is a diagram showing the flicker spectrum, FIG. 5 is a diagram showing the address line driving method in the same embodiment, and FIG. 6 is a diagram showing the signal line driving method in the same embodiment. 7 is a diagram showing the color filter arrangement of the liquid crystal panel in the same example. FIG. 8 is a diagram showing how horizontal stripes occur in the frame when the driving method of FIG. 5 is implemented alone. Fig. 9 shows how diagonal stripes are produced in the frame by combining the driving methods shown in Figs. 5 and 6, and Figs. FIG. 12 is a diagram showing a method of driving a liquid crystal panel; FIG. 12 is a diagram showing a method of dividing a display screen into blocks for explaining another embodiment of the present invention; FIG.
The figures are diagrams for explaining the driving method of the liquid crystal panel in the same embodiment, FIG. 14 is a diagram showing the average brightness spectrum of two pixels adjacent to each other in the vertical scanning direction in the same embodiment, and FIG. 15 16 is a diagram showing the relationship between the number of lines in a block and the flicker improvement rate according to the same example, and FIG. 16 is a diagram showing a liquid crystal panel of a liquid crystal display device using TPT and its driving circuit.
Fig. 17 is a diagram showing an equivalent circuit for one pixel in Fig. 16, Fig. 18 is a drive waveform diagram for explaining the flicker occurrence situation according to the conventional technology, and Fig. 19 shows the conventional flickerless driving method. 2110...Liquid crystal panel 11...Address line 12...Signal line 13...Liquid crystal display element (pixel) 14...Liquid crystal cell 15...TPT 16...Holding capacitor 17...Address line drive circuit (first drive means) 18...Signal line drive circuit (second drive means) 105...Order conversion circuit

Claims (3)

[Claims] (1) A liquid crystal panel in which a plurality of liquid crystal display elements constituting pixels are connected to the intersections of a plurality of address lines along the horizontal scanning direction and a plurality of signal lines along the vertical scanning direction, and the address lines are connected to each other. a first driving means that repeats the operation of sequentially driving every other or every plurality to the bottom edge of the screen, returning to the top of the screen after driving to the bottom of the screen, and sequentially driving every other or every plurality to the bottom of the screen; a second driving means for driving the signal line with an image signal voltage whose polarity is inverted every time the first driving means drives the address line to the bottom edge of the screen and whose polarity is inverted for each signal line or for each plurality of signal lines; A liquid crystal display device comprising a driving means. (2) A liquid crystal panel in which a plurality of liquid crystal display elements constituting pixels are respectively connected to intersections of a plurality of signal lines along the vertical scanning direction and a plurality of address lines along the horizontal scanning direction, and the liquid crystal panel The display screen to be formed is virtually divided into a plurality of blocks, and for each block, the address lines are sequentially driven to the bottom end of the block every other or every second line, and after being driven to the bottom end of the block, they are returned to the top end of the block. a first driving means that repeats an operation of driving every other or every plurality of address lines to the bottom end of the block; and reversing the polarity of the signal line each time the first driving means drives the address line to the bottom end of each block. 1. A liquid crystal display device comprising: second driving means driven by an image signal voltage. (3) A liquid crystal panel in which a plurality of liquid crystal display elements constituting pixels are respectively connected to intersections of a plurality of signal lines along the vertical scanning direction and a plurality of address lines along the horizontal scanning direction, and the liquid crystal panel The display screen to be formed is virtually divided into a plurality of blocks, and for each block, the address lines are sequentially driven to the bottom end of the block every other or every second line, and after being driven to the bottom end of the block, they are returned to the top end of the block. a first driving means that repeats an operation of driving the signal line to the bottom end of the block every other line or every plurality of lines; and a polarity of the signal line is inverted every time the first driving means drives the address line to the bottom end of each block. and a second driving means that is driven by an image signal voltage whose polarity is inverted for each signal line or for each plurality of signal lines.