JPH0343786A - Signal processing circuit for active matrix liquid crystal panel - Google Patents

Abstract

PURPOSE:To eliminate a vertical brightness inclination without reference to whether an image is light or dark by providing a signal processing means which varies a quantity for compensating the vertical brightness inclination according to a picture element potential. CONSTITUTION:Video signals after series/parallel conversion are inputted through a series/parallel converting circuit 7 to X electrodes 4 to which input electrodes of field effect transistors 3 are connected in common, column by column; and a multiplier 12 multiplies a video signal inputted to a video signal input terminal 10 by a correction signal inputted to a correction signal input terminal 11 and an AC converting circuit 13 which converts the output of the multiplier 12 into an AC signal. In this case, the video signal increases in amplitude relatively with time from right after the inversion of the video signal to right before next inversion. Consequently, the vertical brightness inclination can be corrected without reference to whether the image is light or dark.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to field effect transistors, particularly TFTs (TFTs).
The present invention relates to a signal processing circuit for driving an active matrix liquid crystal panel using thin film transistors (thin film transistors).

[Prior Art] In recent years, TPT active matrix liquid crystal panels, which have a structure in which a TPT is connected to each of liquid crystal cells arranged in a matrix to drive the liquid crystal cells, have come into use.

FIG. 5 is an equivalent circuit diagram showing the overall configuration of such a TPT active matrix liquid crystal panel module.

In the figure, (1) is a liquid crystal cell arranged in a matrix, (2) is a storage capacitor connected in parallel with each liquid crystal cell (1), and (3) is one of the liquid crystal cells for each liquid crystal cell (1). These three elements constitute one pixel. (
4) is a field effect transistor (
3) a plurality of X electrodes commonly connected to the input electrode (source electrode), and (5) a FET (
A plurality of Y electrodes are commonly connected to the gate electrode of 3). In addition, (6) is a scanning circuit that sequentially applies scanning pulses to the Y electrode (5), and (7) is a scanning circuit that samples and holds the video signal to convert the video signal for one horizontal scan into the same number of parallel video signals as the X electrodes. A serial/parallel conversion circuit (8) is a common electrode commonly connected to the other electrode of all liquid crystal cells (1). (9) is an AC video signal input terminal for supplying the amplified and AC video signal to the serial/parallel conversion circuit (7) for driving the liquid crystal cell.

Next, a method of driving the TPT active matrix liquid crystal panel module shown in FIG. 5 will be explained. Now, if the i-th electrode of Y electrode (5) is Yl, then Y electrode (5)
For each electrode, for example, Y1 to Y4, Y1 in FIG.
~The waveform signal with timing like Y4 is the scanning circuit (6)
is applied by. When this scanning pulse is applied to the gate of the field effect transistor (3), all the field effect transistors (3) in the selected row are turned on, and charges corresponding to the parallel video signal are transferred from the X electrode (4) to the electric field. Storage capacitor (2) via effect transistor (3)
is charged to. Even if the field effect transistor (3) is turned off, the video signal is sent to the liquid crystal cell (1) by the charge stored in the storage capacitor (2) for one frame period until the next write. Since a voltage corresponding to the voltage is continuously applied, the transmitted light of each liquid crystal cell (1) can be controlled by the video signal and displayed.

It should be noted that the voltage ε of the same polarity continues to be applied to the liquid crystal cell (1).
Due to the problem of shortened lifespan, liquid crystal cells (1)
Taking advantage of the fact that the transmitted light characteristics remain the same even if the polarity of the voltage applied to the voltage is reversed, it is possible to The potential of the pixel electrode is inverted at each frame period.

Therefore, when converting to AC in video signal processing, characteristics as shown in FIG. 7 are used. That is, with respect to the input signal VO, the output signal S is symmetrical about the reference potential VC at positive polarity and negative polarity, such as Vc±(d+bVO).

Here, FIG. 6 shows the level of the common electrode potential VCOH applied to the common electrode (8) of FIG. 5 at the same time as the output signal S.

Originally, if the overall configuration of the TPT active matrix liquid crystal panel module was as shown in Figure 5, V CO
M and VC should match.

However, in reality, the true equivalent circuit of the liquid crystal panel section has become more complicated due to various factors, and as a result, as shown in Figure 6, it is necessary to take the difference ΔV between VC and V COM. It is no longer necessary. The reason for this is shown below in Figure 8.
This will be explained in detail using FIG. 9.

FIG. 8 is an equivalent circuit diagram of one pixel of a realistic TPT active matrix liquid crystal panel. a field effect transistor (3) and a storage capacitor (2) with g=Cm;
The common electrode (8) is the same as the conventional example, and the source (3a) and gate (3b) of the field effect transistor (3) are
They are connected to the X electrode (4) and Y electrode (5) in FIG. 5, respectively. In addition, Cec and Rec are the fifth
The equivalent circuit of the liquid crystal cell (1) shown in the figure corresponds to the capacitance and resistance. Furthermore, Cgd is a gate-drain coupling capacitance caused by the overlap of the gate and drain.

FIG. 9 is a diagram illustrating dynamic characteristics based on the equivalent circuit of FIG. 8, and shows the waveform of the pixel (drain) voltage over a large period of time. First, during the gate selection period (the period in which the gate is ON), the capacitances Cm and Cec are charged to a potential corresponding to the source voltage on both the positive and negative polarity sides. Then the gate is O
At the moment it becomes FF, the amplitude Vg of the gate pulse is equal to the capacitance C
As shown in the figure, the potential shifts by an amount divided by the parallel capacitance of 111 and Cec and the gate-drain coupling capacitance Cgd, that is, gd ΔVgd−@Vg Cm +Cec+Cgd. Then, during approximately one frame period when the gate is OFF, the resistor bone Ree discharges, the potential decreases by ΔVR, and the above cycle is repeated. Therefore, in order to AC drive the liquid crystal in a state close to ideal, it is necessary to bring the potential of the common electrode (8) approximately to the center of the real-time waveform of the pixel (drain) voltage shown in FIG. As such, the actual common electrode potential V COM is lower than the reference potential VC when converting to AC by an amount ΔVc that takes into account the drop ΔVgd due to the gate-drain coupling capacitance Cgd and the drop ΔVR due to the resistor Rec. It is set to .

Next, the influence of the TPT OFF characteristic on image quality, which is the problem of this invention, will be described.

In Fig. 10, when time t is plotted on the horizontal axis and line address is plotted on the vertical axis, the next data is written from the moment it is written to each line of the video signal, which is changed to positive or negative polarity in the frame period. It shows what the polarity is up to the moment. To simplify the explanation, the pixel configuration of the TPT panel is assumed to consist of six lines, with the first line being the top line and the sixth line being the bottom line. From FIG. 10, for example, in the first line (at the top of the screen), the signal supplied to the source path line after being written with positive polarity is always positive until this line is written next.
Furthermore, it can be read that the signal supplied to the source path line after being written to negative polarity is always negative polarity until this line is written next time.

On the other hand, in the 6th line (at the bottom of the screen), contrary to the situation in the 1st line, for example, after the 6th line is written to positive polarity, the signal supplied to the source path line immediately changes to negative polarity. , this situation continues until the next time this line is written. Furthermore, if the sixth line is written to negative polarity, the signal supplied to the source path line will immediately change to positive polarity, and this situation will continue until this line is written next.

Therefore, at the bottom of the screen, there are more drains (pixels) than at the top.
It can be seen that the voltage between the -source and the source tends to remain high for a long time, and this tendency becomes stronger as you move from the second part of the screen toward the bottom. However, in principle, FET (FTP)
-D voltage increases, leakage current 1 during OFF period
OFF will increase. FIG. 11 shows how the voltage of each pixel changes during one frame period due to this influence. In addition, in FIG. 11, in order to simplify the explanation, ΔVgd explained in FIG. 9 and the potential drop ΔVl? due to the resistance bone Rec of the liquid crystal are shown. The effect of is ignored.

The upper part of FIG. 11 shows the signal voltage of the source pass line, the middle part shows the signal voltage of the pixel electrode of the upper line, and the lower part shows the signal voltage of the pixel electrode of the lower line.
It is expressed by taking time t on the horizontal axis. Common electrode (common electrode) written in the upper source path line signal in the figure
The potential VCON is set to VCON-Vc, ignoring the influence of ΔVgd, as described above. In addition, the signal supplied to the source is the positive polarity side Vc + (d+bVO)
, the negative polarity side Vc - (d+bVO), which is a white peak signal, is charged or discharged to the above potential at the moment it is written into each pixel via TPT.

First, if we pay attention to the middle row of FIG. 11 (pixel signals of the upper line), at the moment the upper line is written, VCOM±(d
After that, the polarity of the signal supplied to the source path line is mostly the same as the polarity at the moment of writing during one frame, and the potential difference between S and D is small, so the signal is turned OFF. The leakage current during the period 1 OFF is sufficiently low, and therefore the pixel potential hardly changes. However, the leakage current during the OFF period is 1OFF, which is a short time after the polarity of the source signal changes until the upper line is selected.
There will be some impact from the increase in

Next, paying attention to the lower part of FIG. 11 (pixel signals of the lower line), at the moment when the lower line is written, VCOM±(d
+bVo), but soon after that, the polarity of the signal on the source path line is reversed, so the potential difference between S and D is large for most of the 171 node period, and the OFF
Due to the influence of the increase in leakage current I OFF during the period, the pixel potential fluctuates as shown in the figure.

FIG. 12 shows temporal fluctuations in the absolute value of the potential difference between the pixel electrodes and the common electrode at the top and bottom of the screen.

Since a liquid crystal responds in proportion to the effective value of the potential difference between its two ends, if there is a difference between the top and bottom of the screen as shown in Figure 12, the effective value at the bottom of the screen will be smaller than the top, which will appear as a vertical brightness gradient. , the image quality will deteriorate significantly.

Conventionally, as a countermeasure to this kind of problem, a driving method has been adopted in which the polarity is reversed even in the line period, taking into account that the alternating current cycle of each pixel is one frame, as shown in Figure 13. Ta.

Note that the view of FIG. 13 is the same as that of FIG. 10. According to such a driving method, even in the first line, the sixth line
Also in the line, for each pixel potential, a signal of the opposite polarity is supplied to the source path line for approximately the same period of time.

Figure 14 shows this situation.
It is similar to that in the figure. As is clear from the figure, for both the second line and the lower line, the leakage current is 1 during the OFF period, which is a period in which a signal with a polarity opposite to that written in each line is supplied to the source path line in one frame. There is an effect of an increase in OFF.

Similarly to FIG. 12, FIG. 15 shows how the absolute value of the potential difference between the pixel electrode and the common electrode changes over time for the upper line and the lower line. According to this method, the potential fluctuations of each pixel at the top and bottom of the screen are almost the same as shown in the figure, so the vertical brightness gradient described above is eliminated.

However, according to such a driving method, the signal supplied to the source path line is a high-frequency signal that is inverted at the line period, compared to frame inversion. However, in general, TF
The load capacitance of the source path line of the T panel is the driver I
It is not so small that it can be ignored with respect to the C output impedance, and increasing the frequency of the source path line signal in this way leads to a decrease in its effective value. To compensate for this, it was necessary to supply a signal with a large amplitude in advance so that the effective value of q could be reduced. This not only causes an increase in the dynamic range of the video signal processing unit and the source driver, but also an increase in power consumption.In particular, for the source driver, this is a result that contradicts the trend of increasing the scale of LSI integration from the perspective of compact packaging. The negative effects were fatal.

Therefore, as a driving method that takes the above-mentioned problems into consideration, a method has been proposed in which the source signal is frame-inverted as in the conventional method, and a correction signal synchronized with the source signal as shown in Fig. 16 is added to the common side. .

This driving method is explained in comparison with Fig. 14 in the first part.
This is Figure 7.

In Figure 17, the upper row shows the signals of the source pass line and common electrode of Figure 16 at the same time, the middle row shows the voltage of the pixel electrode on the upper line, and the lower row shows the fluctuations in the voltage of the pixel electrode on the lower line. Each situation is expressed using time on the horizontal axis.

In the middle and lower diagrams, the dotted lines indicate the voltage of the common electrode at each time, and are the same signals as those in the upper diagram of FIG. 17.

First, pixel voltage fluctuations in the middle upper line will be explained. The moment the upper line is written, ■COH±(d+b
After that, the polarity of the signal supplied to the source path line is mostly the same as the polarity at the moment of writing during one frame, and the potential difference between S and D is small, so the signal is turned OFF. Leakage current during the period 1 Almost no voltage fluctuation occurs at the pixel electrode due to the OFF period. However, except for the write period, the TPT is in the OFF state and the pixel electrode is equivalent to an open state from a circuit perspective, so fluctuations in the common electrode voltage are directly applied through the capacitance Cecs Cyg, etc. The changes are as follows.

Next, the lower part of FIG. 17 (voltage fluctuation of the pixel electrode in the lower line) will be explained. The moment the bottom line is written, V
The potential becomes CON±(d+bVo), but shortly thereafter, the polarity of the signal on the source path line is reversed, so the potential difference between S and D is large for most of the period during one frame, and the leakage current 1 There is an effect of an increase in OFF. Therefore, if there is no variation in the common electrode potential, a decreasing characteristic of the holding period as shown in the lower part of FIG. 11 will appear. However, as described above, since the fluctuations in the common electrode potential are directly added through the capacitances *Cec, .

FIG. 18 shows temporal fluctuations in the absolute value of the potential difference between the pixel electrode and the common electrode at the top and bottom of the screen in the case of FIG. 17. As can be seen from this figure, the AC potential difference between the pixel electrode and the common electrode changes in the same way as in the conventional example shown in FIG. 12.

However, since the common electrode potential at the time of writing is different between the time when the upper part of the screen is written and the time when the lower part of the screen is written, the DC potential difference between the pixel electrode and the common electrode is different from that in Fig. 12. .

As a result, as shown by the dotted line in FIG. 18, the average level can be made the same at the top and bottom of the screen.

Here, the signal applied to the common electrode is a sawtooth wave,
The falling characteristic of the holding period was also made linear, so the average value was the same at the top and bottom, but in consideration of the falling characteristic due to leakage current 1 OFF, etc., the effective value was made equal at the top and bottom of the screen. By devising the signal applied to the common electrode and controlling the DC potential difference, it is possible to compensate for the vertical brightness gradient without increasing the frequency of the source signal (line inversion) due to the effective value response of the liquid crystal. This is the translation.

However, when considering the principle of occurrence of vertical brightness gradient, both of the above two methods have a common problem.

That is, in both of the above two methods, although it is possible to improve the luminance difference caused by the influence of the polarity of the source signal between the upper and lower parts of the screen, it is not possible to improve the luminance difference caused by the difference in the voltage level of each pixel.

For example, in the case of the white peak signal shown in the upper part of Figure 11, the falling characteristic of the pixel voltage in the lower line is as shown in the lower part of the figure.
In the case of a black peak signal, the difference between the source signal and pixel voltage between positive and negative polarities is not as large as in the case of a white peak signal.
The influence of the leakage current I OFF is also small, and the vertical luminance gradient amount depends not only on the line address but also on the pixel potential.

Therefore, when displaying a gray scale like the one shown in the upper row of FIG. 19, the conventional method for improving the vertical brightness gradient
When the vertical brightness gradient is corrected according to the bright level, a vertical brightness gradient occurs on the dark side, as shown in the middle row of the figure. Conversely, if the vertical brightness gradient is corrected according to the dark level, a vertical brightness gradient will occur on the concave side, as shown in the lower part of the figure. In such cases, it may be possible to use human perceptual characteristics to correct the level of the dark side, which is sensitive to visual characteristics, but as the screen size becomes larger, especially as the number of vertical lines increases, this tendency becomes less As this becomes more and more noticeable, even the brightness slope on the concave side becomes noticeable, and as the screen becomes larger, the image quality tends to deteriorate.

[Problems to be Solved by the Invention] Conventional Problems The conventional driving method for improving the vertical luminance gradient of a TPT liquid crystal panel is as described above, so that it is not possible to correct the difference in the amount of vertical luminance gradient due to the influence of pixel potential. First, there were problems such as a vertical brightness gradient occurring due to the brightness of the image.

Therefore, there is a problem that the above problems must be solved.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a signal processing circuit for a TPT active matrix liquid crystal panel that can improve the vertical luminance gradient regardless of the brightness or darkness of the image.

[Means for Solving the Problems] A signal processing circuit for an active matrix liquid crystal panel according to the present invention has a field effect transistor arranged in each of the liquid crystal cells arranged in a matrix to form a matrix arrangement. A scanning pulse is sequentially applied to a plurality of Y electrodes in which the gate electrodes of field effect transistors arranged in each row are commonly connected, and the input electrodes of the field effect transistors are connected in common to a number of stages of X electrodes in each column. , a signal processing circuit that supplies a video signal to an active matrix liquid crystal panel configured to input a video signal converted into serial/parallel data via a serial/parallel conversion circuit. The signal circuit for an active matrix liquid crystal panel according to the present invention includes a video signal input terminal,
A correction signal input terminal, a multiplier that multiplies the video signal input to the video signal input terminal and the correction signal input to the correction signal input terminal, and an AC conversion circuit that converts the output of the multiplier to AC. The multiplier and the correction signal are configured to relatively increase the amplitude of the video signal that is inverted in a frame period as time passes from immediately after the video signal is inverted to immediately before the next inversion. It is characterized by:

"Function" In the signal processing circuit for an active matrix liquid crystal panel according to the present invention, as the time changes from immediately after the source signal, that is, the video signal is inverted to immediately before the next inversion, the amplitude of the video signal changes relatively. By increasing the size of the image, it is possible to obtain the same effect as changing the amount of correction of the vertical brightness gradient depending on the pixel potential, and therefore, it is possible to correct the vertical brightness gradient regardless of the brightness or darkness of the image. be.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

The configuration of the TPT liquid crystal panel module is as shown in FIG. 5, and has already been explained in detail in the description of the conventional example, so a repeated explanation will be omitted. The method of alternating current is the same as that of the conventional example shown in FIG. 10, and the driving means on the common side is the same as that shown in FIG. 16, so a description thereof will be omitted.

The present invention differs from the conventional example described above in that the AC video signal supplied to the AC video signal input terminal (9) in FIG. 5 is obtained by a signal processing circuit configured as shown in FIG. 1, for example. This is the point where the signal is S (t, y).

In Figure 1, (10) is the video signal input terminal to which the video signal g (t) is supplied, and (11) is the time change from immediately after the inversion of the source signal, which is inverted at the frame period, to immediately before the next inversion. This is a correction signal input terminal to which a correction signal f (t) that becomes relatively larger as At the same time as it is a function, it is also a signal that increases as the line order increases from the top line to the bottom line, as shown in Figure 3, for example, as shown in Figure 3, so it is easy to understand when explaining. This correction signal is used for the purpose of f (Y)
It is described as follows. (12) is a multiplier that multiplies the video signal g (t) and the correction signal f (y), and (13) is a multiplier (
12) is an AC converting circuit that converts the output of
is input.

Next, a process of improving the vertical brightness gradient according to the present invention will be described.

The conventional AC video signal can be written as VC±(d+bVO), as shown in FIG. 7 of the conventional example.

Since vO varies over time depending on the signal to be displayed, V
It is written as O(t). Here, we will replace the above equation with the following equation.

VC±(d+bVO(t) -Vc±(a+g(t))...(1) In the above equation, g(t) corresponds to the signal supplied to the video signal input terminal (10) in Figure 1. , a corresponds to the average area of the offset mainly due to d in equation (1).

Here, if the vertical brightness slope is the leakage current i of TPT
Assuming that driving by TPT rather than by or'p is ideal, and assuming that the vertical luminance gradient is caused by the source signal, the signal is expressed by the following equation, as described in the explanation of the conventional example. It can be seen that the signal is supplied.

VC±(a+g (t)-ay (y) gY (
V)... (2) In the above equation, ay (y) is a term that depends only on line address y, and gY (y) is a term that depends not only on line address y but also on video signal level g (t). This term represents the vertical brightness gradient.

Now, let F (y) be the basic formula representing a non-negative brightness gradient that increases as the line address y increases, that is, from the top line to the bottom line, (2)
The equation can be expressed approximately as shown below.

VC±(a0g (t)-ay (y)-gy(y)) -VC±(a+g (t) -F (y) ・a-F
(y) ・g (t) ) ・・
・(3) Therefore, the vertical brightness slope improvement method that relies only on the line address, such as correction on the common side in Figure 16, corrects the third term F (y) ・a in the parentheses of equation (3). After applying the means shown in FIG. 16, the source signal can be expressed and expanded as shown in the following equation.

Vc ± (a+g (t) -F (!/)
' g (t) )−Ve ± (a+g (t
) (1-F (y) )... (4) Therefore, in order to correct the vertical luminance gradient according to this video signal g(1), f (y
) -1/(1-F(y)), the coefficient (1-F(y)) in the second term to the west of the parentheses in equation (4) can be eliminated, and as a result, the vertical luminance The slope can be improved.

This signal f (y), which increases with the line address so as to eliminate the vertical luminance gradient, corresponds to the correction signal f CY> in FIGS. 1 and 3.

Therefore, in the configuration shown in Figure 1, by varying the drive voltage using the line address and adding a signal to the common side that can compensate for the influence of a-F (y) using the means shown in Figure 16, The vertical brightness gradient can be almost completely improved.

In the above embodiment, the compensation for a-F(y) in the third equation, which depends only on the line address, is dealt with on the common side. However, if there is sufficient dynamic range on the source signal side, This amount can also be compensated for on the source signal side. In this case, equation (3) is Vc±(a0g (t)−a−F (y) ・g (t
)・F(y)) -VC±(a(1-F(y))+g(t)(1-F(y))...(5
), and the first term in parentheses a (1-F(
In order to eliminate line address dependence of y)), 1/(1-F
(y) ). The configuration of the signal processing circuit in this case is shown in FIG.

The circuit in FIG. 4 basically has the same configuration as in FIG. 1, but a correction signal input terminal (14) is newly provided, and a correction signal h (y ) -a · (1-F (y) ) is added to the output of the multiplier "5 (12) by the adder (15) for the above-mentioned reason, and then converted to alternating current."

Note that the source signal corrected as above is vc±(h (!/) 10g (,t) ・f(y))
-VC±(a-f (Y) +g (t) ・f □
/))-Ve±f (y)(a+g (t))-Vc
f (!/) (d+bVO) -VC± (d+bVo) 1-F (y) ... (6) As shown in Figure 2, the signal covering all levels from the dark level to the bright level is The level corresponds to the function f (5/) of address y.

[Effects of the Invention] As described above, according to the present invention, depending on the pixel potential,
With a configuration that includes a signal processing means that can change the intensity of compensation for vertical brightness gradients, it is possible to eliminate vertical brightness gradients regardless of the brightness or darkness of the image, resulting in the effect of significantly improving the image quality displayed by a TPT active matrix liquid crystal panel. There is.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of a signal processing circuit for obtaining an AC video signal according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams for explaining driving according to the present invention, and FIG. 4 is a circuit configuration diagram of another signal processing circuit for obtaining an AC video signal of the present invention, FIG. 5 is an equivalent circuit diagram showing the overall configuration of a conventional TPT liquid crystal panel module and a TPT liquid crystal panel module of the present invention, and FIGS. 6 and 7 are The figure is an explanatory diagram for explaining the display principle of a TPT liquid crystal panel, Figure 8 is a detailed equivalent circuit diagram of one pixel of the liquid crystal panel, and Figure 9 is a state of pixel potential fluctuation when using a conventional drive method. Explanatory diagram showing details, No. 10.11.12
Figures 13, 14, and 15 are explanatory diagrams for explaining the principle of vertical luminance gradient generation using the conventional frame inversion driving method. Figures 13, 14, and 15 are explanatory diagrams for explaining the process of improving the vertical luminance gradient using the conventional line inversion driving method. , Figures 16, 17, and 18 are explanatory diagrams for explaining the conventional process of improving the vertical luminance gradient from the common side, and Figure 19 is an explanatory diagram for explaining the problems of the conventional method for improving the vertical luminance gradient. It is. In the figure, (1) is a liquid crystal cell, (2) is a storage capacitor, (3) is a field effect transistor, (4) is an X electrode, (5) is a Y electrode, (6) is a scanning circuit, (7) is (8) is a common electrode, (9) is an AC video signal input terminal, (10) is a video signal input terminal, (11) is a correction signal input terminal, (12) is a multiplier, ( 13) is an alternating circuit, (14) is a correction signal input terminal, and (15) is an adder. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A field effect transistor is provided in each of the liquid crystal cells arranged in a matrix, and the gate electrodes of the field effect transistors arranged in the matrix are sequentially scanned to a plurality of Y electrodes commonly connected in each row. It was configured to apply a pulse and input a video signal converted into series/parallel via a serial/parallel conversion circuit to a plurality of X electrodes in which the input electrodes of the field effect transistors were commonly connected for each column. A signal processing circuit that supplies a video signal to an active matrix liquid crystal panel, comprising a video signal input terminal, a correction signal input terminal, and a video signal input to the video signal input terminal and a correction signal input terminal. The multiplier includes a multiplier that multiplies the output of the multiplier by a correction signal, and an AC converting circuit that converts the output of the multiplier to AC, and the multiplier and the correction signal multiply the video signal before converting to AC by the correction signal, and adjust the frame period. An active matrix liquid crystal panel characterized in that the amplitude of a video signal is relatively increased as time passes from immediately after the video signal is inverted to immediately before the next inversion. signal processing circuit.