JP3253331B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple matrix type image display device used for a computer, a word processor and the like.

[0002]

2. Description of the Related Art FIG. 9 is a diagram showing the configuration of a pixel of a simple matrix type image display device, in which (I, J) to (I + 1, J +).
1 shows four pixels. Liquid crystal 1 of pixel (I, J)
53 is sandwiched between row electrodes 151 and column electrodes 152 that are arranged orthogonally. A plurality of transparent row electrodes parallel to the row electrode 151 are formed on one glass substrate, and a plurality of transparent column electrodes parallel to the column electrode 152 are formed on the opposite glass substrate. An image is displayed by controlling the voltage of the enclosed liquid crystal for each pixel with the intersecting electrodes. R (I), R (I
+1) is the signal of the row electrode of row I and row (I + 1),
(J) and S (J + 1) are signals of the column electrodes in the J and (J + 1) columns.

FIG. 10 is a screen view of a liquid crystal display for explaining "display unevenness". 161 is a column-side drive circuit for supplying a signal to a column electrode of the liquid crystal display, and 162 is a row-side drive circuit for transmitting a signal to a row electrode. The right half of the screen is mostly black solid 1
In the display of 63, there is a white portion 164 on the lower side. The left half is the white part 1 below the display where the horizontal stripes of the black part 165 and white part 166 are repeated.
There are 67. In this display pattern, black 165 on the left half is blacker than black 163 on the right half, and white 166,1 on the left half.
The white 164 on the right half surface is whiter than 67, and black and white are each “uneven display” which is not uniform in density.

FIG. 11 is a driving signal diagram of a liquid crystal for explaining "display unevenness". FIG. 11 (a) is a potential diagram of a signal of a row electrode and lighting and non-lighting of a column electrode, and FIG. Left half 1
FIG. 11C is a drive signal diagram applied to the liquid crystal in the 67 portion of the liquid crystal, and FIG. 10C is a drive signal diagram applied to the liquid crystal in the right half surface 164 of the screen of FIG.

[0005] signal of the row electrodes in (a) is a period of non-selection potential V ₅ shown in 171, the selection potential V shown in 172
_In the next frame in which there is a selection period for one row of pixels and the polarity is inverted due to the AC driving of the liquid crystal, the non-selection period is 17
3, the non-selection potential V ₂ , and the selection period is 174 selection potentials V ₆
It has become. Reference numerals 175 and 177 denote the non-lighting potential V ₄ and the lighting potential V ₆ of the column electrodes, respectively, and 176 and 178 denote the non-lighting potential V ₃ and the lighting potential V in the frame whose polarity is inverted.
_Is one. V _K −V _{K + 1} = V (K = 1, 2, 4, 5) and the same voltage.

(B) and (c) show the voltage applied to the liquid crystal between the row electrode and the column electrode. 179 and 182 are 167,
The liquid crystal of the 164 portion is in the selection period, and is (selection potential (V ₁ ) −image signal potential (V ₆ )). 18
0, 183 are in the non-selection period, and (the non-selection potential (V ₅ ,
V ₂₎ - an image signal potential _{(V 4} or _V 6, _{V 3} or _V 1)). Polarity of the next selection period 181 and 184 in the voltage applied to the liquid crystal _(V 6 -V ₁₎ is inverted. 1
In the next frame after 181 and 184, the polarity of the signal for one frame period from 79, 182 to immediately before 181 and 184 is inverted and AC driving is performed.

[0007] Comparing the shaded portions (b) and (c), the lighting (white) and the non-lighting (black) in the column direction as shown in the left half of FIG.
In a pattern with a large number of repetitions, when the image signal is inverted between the lighting potential and the non-lighting potential, the response waveform of the drive signal voltage applied to the liquid crystal bends due to the signal output resistance, electrode resistance, and liquid crystal capacitance. The area of the hatched portion is smaller than that of the pattern in which the image signal does not change as in the right half plane. Accordingly, both the black and white pixels on the left half surface have a lower driving effective voltage than the right half surface, resulting in “display unevenness”.

In recent years, an image display device having a larger area and a higher definition uses a super twist type liquid crystal display system in which a transmittance-voltage curve is steep, but the number of row electrodes increases and the selection period becomes longer. The drive effective voltage for distinguishing between lighting and non-lighting became shorter, and the above-mentioned "display unevenness" began to be a disadvantage that was easily recognized depending on the pattern, as compared with a fine character display and a large pattern. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to improve the display unevenness by using an improved driving method which has not been known hitherto. Are newly provided.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has a structure in which a substrate on which a plurality of row electrodes are formed and a counter substrate on which a plurality of column electrodes are formed are provided. A liquid crystal is sandwiched, a potential signal for setting a pixel to a selection potential or a non-selection potential is sent to the row electrode for each row, and the column electrode is turned on or off.
Sends an image signal corresponding to the two states of the non-lighting state, in the image display apparatus driven by alternating current by inverting a frame period the polarity of the drive signal applied to the liquid crystal, the period of one frame period
In each of the two rows,
If the polarity of the dynamic signal is inverted is provided, as a potential of (A) an image signal, the lighting voltage to the non-selection potential, non-lighting voltage, the corrected lighting voltage 及 beauty corrected non-lighting voltage
And a first potential group having the first potential group.
Kano, (1) lit potential correction lighting potential of the image signal lighting state
Given as potential, (2) non-lighting voltage and the corrected non-lighting voltage is given as a potential of an image signal of the non-lighting state, (3) and the voltage between the lighting potential and the non-selection potential, the non-selection potential and the non (4) The voltage between the corrected lighting potential and the non-selection potential is made higher than the voltage between the lighting potential and the non-selection potential, and (5) the corrected non-lighting potential correction lighting potential is a relationship which is inverted referenced to non-selection potential was further supplied with the potential of the image signal when the (B) polarity reversal
For example, the second potential in which each potential of the first potential group is inverted
Potential group is provided, and the potential signal applied to the liquid crystal of the (C) a row electrode, the image
The potential relationship with the signal is inverted from the potential relationship in the previous row.
If not, select from the potential group used in the previous row.
Lighting potential or non-lighting potential is applied as the potential of the image signal.
Erare, (D) potential signal and the potential relationship one line before and inversion of the image signal
In the next row period, the potential group different from that of the previous row
Selected lighting potential or OFF potential No. image signal from the electrical
Given as position, (E) in the case of the above (C), one line prior to the image signals
Is the non-lighting potential and the image signal of the next row is the lighting potential
When the image signal of the previous line is the lighting potential and the image of the next line
When the signal is at the non-lighting potential, and in the case of the above (D)
And the image signal of the previous line is the lighting potential and
Is the lighting potential, the image signal of the previous line is
The non-lighting potential and the image signal of the next row is the non-lighting potential
Sometimes, a non-selection potential in a group of potentials
The image signal is inverted, and during the selection period of that row,
Correcting the lighting voltage or the corrected non-lighting <br/> conductive position from among the potential group of need to provide an image display apparatus characterized by being et given as the potential of the selected image signal.

[0011]

According to the present invention, when the image signal applied to the column electrode is inverted with reference to the non-selection potential of the row electrode, compared to the non-inverted state, the image signal of one row is applied to the period during which the image signal is applied to the column electrode. The image signal voltage based on the non-selection potential of the column electrode is increased. By doing so, the effective voltage drop caused by the bending of the drive response waveform as shown by the hatched portion in FIG. 11B compared with the hatched portion in FIG.
"Display unevenness" is reduced.

[0012]

FIG. 1 is a driving signal diagram of a liquid crystal of an image display device according to the present invention, and shows a voltage applied to a liquid crystal between a row electrode and a column electrode. 1 is a selection period, and (selection potential−
2 to 6 are non-selection periods, and a voltage of (non-selection potential-image signal potential) is applied to the liquid crystal. In 3 subsequent to 2, in 5 subsequent to 4, the image signal potential is inverted with reference to the non-selection potential corresponding to the voltage 0 in the non-selection period, and in 3 and 5, the liquid crystal during one horizontal scanning period in which one row of pixels is selected. Is applied with a voltage of V ⁺ . 4 following 3 and 6 following 5 represent that the image signal is in the same state of the lighting potential and the non-lighting potential and does not cross the non-selection potential and is not inverted.
Voltage is applied. With the image signal voltage based on the non-selection potential, V ⁺ is adjusted to be larger than V to correct a decrease in the effective driving voltage associated with the inversion of the image signal.

FIG. 2 is a power supply circuit diagram for generating a liquid crystal drive potential of the image display device of the present invention. Resistance R between power supply V _CC and V _ZZ
5, transistor of R ₅ and the emitter follower 11
Are connected in series to divide the voltage, and the power supply V _CC and the transistor 11
Between the emitter potentials V _{EE of the} two, voltage follower 1
2 outputs the intermediate potential _VMM . The voltage between the power supply V _CC and V _ZZ is _divided by a resistor R ₆ and a variable resistor R ₇ to form a transistor 1
1 and adjust the potentials of V _EE and V _MM with respect to V _CC by changing the variable resistor R ₇ .

Reference numeral 14 denotes a regulator which sets the reference COM to V _CC and the input IN to the potential V _LL to generate the potential of V _SS , and
Reference numeral 5 denotes a regulator which sets the reference COM to V _SS and the input IN to V _CC, and outputs a potential of V _DD . Input resistance is R,
Inverting amplifier 16 and the feedback resistors R is outputting the potential of the inverting the potential of V _DD relative to the V _MM V _BB. V _DD
-V _SS power supply voltage of the logic circuit portion of the liquid crystal driving circuit, V _DD
−V _BB is a power supply voltage of the liquid crystal drive output circuit portion.

The voltage between the power supply V _CC and V _EE is _divided by the resistors R ₈ and R ₉ and input to the base of the transistor 13. The collector outputs the potential V _{LL through} the emitter follower having the potential V _ZZ . Resistor R ₁₀ is the load. V _LL is the input potential of the regulator 14, and the power supply potential on the positive electrode side is V _CC
Are used for the power supply potential on the negative side of the operational amplifiers 17 to 21. In this circuit, the resistance R ₉ can be V _ZZ instead of V _EE . Capacities C ₃ , C ₄ , C ₅ , C ₆ , C
_7, C ₈ are for the stabilization of the potential.

Similarly, resistances R ₁₁ and R ₁₂ are applied between the potentials V _CC and V _EE.
In divided and input to the base of the transistor 27, a load resistor and outputs a potential of V _PP in emitter follower to R _10. The voltage division ratio of the resistors R ₁₁ and R ₁₂ is determined so that V _PP is higher than V _MM , and the positive power supply of the operational amplifiers 12, 16, 22 to 26 has a negative power supply potential of V _EE. Used for potential.

The power supply potentials of V _CC , V _DD , V _SS , and V _ZZ are V
For example, assuming that _CC is the reference 0 V, for example, V _DD = −5 V, V _SS = −10
v, V _ZZ = −40v. Since V _LL and V _PP can be the potentials of (V _EE (or V _ZZ ) + constant voltage) and (V _CC -constant voltage), the resistors R ₉ and R ₁₁ are Zener diodes and R ₈ and R as necessary. _A configuration in which a resistance lower than ₁₂ is connected in series and input to the bases of the transistors 13 and 27 may be adopted. V _LL ,
V _PP is also (V _CC -constant voltage), (V _EE + constant voltage (>
V _MM )), instead of the resistors R ₈ and R ₁₂ , a Zener diode may be connected between the potentials V _CC and V _EE and the base of the transistor, and the resistors R ₉ and R ₁₁ may be connected in series. . If the power supply potential is selected within the rated range of the regulator and the operational amplifier, the regulator 14 is replaced with V _ZZ and the operational amplifiers 12, 16, and 17 instead of the potentials of V _LL and V _PP.
26 can be set to V _CC and V _EE .

A resistor R ₄ and a diode D ₁ , a variable resistor R ₃ , and resistors R ₁ , R ₁ and R ₂ are connected in series between the potentials V _DD and V _MM to divide the voltage, and the potential at each point is applied to a voltage follower 17. ~ 20
To generate potentials of V ₁ ⁺ , V ₁ , V ₂ and V ₃ respectively. The lighting potential V ₁ , the row non-selection potential V ₂ , and the non-lighting potential V ₃ are V ₁ −V ₂ = V ₂ −V ₃ = V. FIG.
V ⁺ of the correction voltage at the time of image signal changes illustrated in varies the variable resistance R _3, corrected lighting voltage V ₁ ⁺ -V ₂ = V ⁺ to. The corrected non-lighting potential V ₃ ⁺ is formed by inverting the corrected lighting potential V ₁ ⁺ by an inverting amplifier 21 with reference to a potential corresponding to the non-selection potential V ₂ stabilized by the capacitor C ₃ . Usually, the feedback resistance of the inverting amplifier is set equal to the input resistance R, and V ₁ ⁺ −V ₂ = V ₂ −V ₃ ⁺ . Selection potential line is equal to the lighting voltage V ₆ of the polarity inversion time, which will be described later. in this way
Then, the first potential group is provided in advance.

The potentials V ₄ ⁺ , V ₄ , V ₅ , and V ₄ ⁺ of the second potential group for inverting the polarity of the signal of the row electrode and the column electrode are used.
V ₆ and V ₆ ⁺ are the inverting amplifiers 2 having the potentials of V ₃ ⁺ , V ₃ , V ₂ , V ₁ and V ₁ ⁺ as input resistors and feedback resistors, respectively.
In 2-26, are making is inverted with respect to the V _MM.
V ₄ ⁺ is a corrected non-lighting potential, V ₄ is a non-lighting potential, V ₅ is a row non-selection potential, V ₆ is a lighting potential, and V ₆ ⁺ is a corrected lighting potential. Thus ^{_{V 4 + -V 5 = V 5}} -V 6 + = a V ^+, the correction potential is adjusted in conjunction with ₃ single variable resistor R. Selection potential line at the time of polarity inversion is equal to the lighting voltage V ₁ described above. Capacitors C ₁ and C ₂ are for stabilizing the liquid crystal driving potential.

When the response waveform differs between the non-lighting potential and the lighting potential depending on the direction in which the image signal changes with reference to the non-selection potential of the row and fine adjustment is required, a corrected non-lighting potential V ₃ ⁺ is output. The input or feedback resistance of the inverting amplifier 21 is finely adjusted. In the figure, a variable fine adjustment resistor R _V is provided in series with R as a feedback resistor.

If it is necessary to separate the divided voltage input to the operational amplifiers 17 to 20 or the potential connected to the input resistance of the operational amplifiers 21 to 26 from the potential for driving the liquid crystal, the output of the operational amplifiers 17 to 26 is required. The capacitors C ₁ and C ₂ are removed, and output is performed by a voltage follower, and the capacitors C ₁ and C ₂ are attached to the output terminals.

The corrected lighting potential V ₁ ⁺ is obtained by using an inverting amplifier capable of adjusting the feedback resistance / input resistance ratio to be larger than 1 in place of the operational amplifier 17 with reference to a potential corresponding to the non-selection potential V _{2. 3} can be made by inverting amplification. At that time R ₃ is a short-circuit.

The voltage dividing circuit is formed between the potentials of V _CC and V _MM , and R ₄ and R ₄ are set so that the potentials of V ₁ ⁺ and V ₁ become lower than V _DD.
A resistance ratio of ₁ , R ₁ and R ₂ may be selected. A Zener diode having a Zener voltage higher than (V _CC -V _DD ) can be used instead of R ₄ , and the diode D ₁ may be short-circuited. The voltage _dividing mechanism between V _CC and V _MM is V _EE
In the direction of inversion in the direction, and V _CC and V _EE
It is also possible to divide the voltage for output of the potentials of ₁ , V ₂ , V ₃ , V ₄ , V ₅ , and V ₆ , and output a voltage other than the correction potential by a voltage follower.

The operational amplifier for outputting the liquid crystal driving potential can be a parallel connection of two or more operational amplifiers.
In particular, it is preferable that a plurality of operational amplifiers for outputting the non-selection potentials V ₂ and V _{5 of the} row electrodes and the power supply potential V _BB of the liquid crystal drive output circuit be connected in parallel to have a low output resistance.

The liquid crystal driving potential is V _DD ≧ V ₁ ⁺ ≧ V ₁ > V _{2
^{> V 3 ≧ V 3 +>}} V MM> V 4 + ≧ V 4> V 5> V 6 ≧ V 6 + ≧
V _BB , the power supply potential on the positive side of the operational amplifier that outputs V _{1 to} V ₃ is V _CC , the power supply potential on the negative side of the operational amplifier that outputs V _{4 to} V ₆ is V _EE , against it (V _CC -V _DD) above wide supply potential of both poles of the operational amplifier voltage, such that (V _CC -V _LL) and (V _PP -V _EE) is substantially equal voltage, V _LL And V _PP are set.

FIG. 3 is a drive circuit diagram on the column side of the image display device of the present invention. 31 transfers the horizontal start signal _HST with the clock CP, and outputs the sampling signals C (1), C (2),
Are output, and the output of the shift register is common to the circuits in column a sampling the image signals one by one on the image signal bus DD. a
Is selected to be 4 or 8.

[0027] 32 is a latch, a shift register output C (1) and the enable input G _1, an image signal DD
Is input to I ₁ and latched by the signal of C (1).
A flip-flop 33 uses the enable signal LP for updating the signal of the column electrode as the clock CL ₂ and the output Q _{1 of the} latch 32 as the input I _2. LP is changed from “1” (= V _DD ) to “0” (= V _DD ). _Vss ), the signal is updated. 34 is a flip-flop to the clock CL ₃ enable signal LP Similarly, the output Q ₂ of the flip-flop 33 I ₃
Input to the signal of the flip-flop 33 as Q ₃ the signal immediately before one horizontal scanning period to be updated, is output in synchronization with the enable signal LP '0'.

The signal M for identifying the selection period of the pixel in one row at the time when the polarity of the signal of the row electrode and the column electrode is inverted by “0” is
'1' by the switch 35 to select the inverted signal Q ₃ ^* output Q ₃ of flip-flop 34, a switch 36 with a '1' output '0', the inverter 57 to choose Q _3,
An exclusive OR 37 with the output Q ₂ of the flip-flop 33 is taken. 37 is '1' if the signal Q ₂ is in the same state as the previous row, '0' if the signal Q ₂ is different, and '0' if the signal Q ₂ is in the same state at the time of polarity reversal of M = '0'; Become.
The time when the image signal of the column electrode is inverted with respect to the non-selection potential of the row electrode corresponds to “0”, and the non-inversion corresponds to “1”.

F is a signal designating the selection of a correction function when the image signal changes. T is a horizontal scanning period during correction, that is, a selection period of pixels in one row, and a potential actually turned on and off is defined as a correction potential. This is a signal that determines the period of time to perform. Signal F is '1'
Designates the correction, T is the correction potential at the time of correction "0", and "1"
To select a non-correction potential. The signal T is inverted by the inverter 58, the NAND 59 is taken together with the F, the output thereof is taken OR 38 together with the output of the exclusive OR 37,
The NAND 39 between the output of the OR 38 and the signal F is taken.

The output Q ₂ of the flip-flop 33 is represented by I _Q ,
The output of OR 38 I _X, the output of NAND 39 as I _Y, converted to V _DD -V _BB potential level of the signal from the V _DD -V _SS at the level converting circuit 40, and outputs Q, X, as Y ing. Q ^* is an inverted signal of Q.

The polarity inversion signal PO converts from V _DD -V _SS to V _DD -V _BB potential level of the signal at the circuit of 60~62, P and buffer at 63 and 64, the inverted signal of the P P ^* And Illuminated, non-illuminated image signals Q, Q ^* , uncorrected,
The AND signals 41 to 44 and NANDs 45 to 48 are taken by three inputs of the correction selection signals X and Y and the polarity signals P and P ^* , and the N-channel transistors 49 to 52 and the P-channel transistors 53 to 56 are controlled to control the liquid crystal. Driving potential bus V
The potential is selected more, and the image signal S (1) of the first column is output.

When the correction function of signal F is "1", Y is X
Is an inversion signal of. When the signal T is “0”, X is “1” and Y is “0” at the time of non-correction, and X is “0” and Y is “1” at the time of correction. For (Q, X, P), (1, 1,
In 1), the transistor 55 is turned on by the NAND 47, and S
(1) is the lighting potential V _1, and in (0, ₁ , 1), the transistor 54 is turned on by the NAND 46 and the non-lighting potential V ₃ ,
In ( ₁ , 0, 1), the transistor 56 is turned on by the NAND 48 to turn on the corrected lighting potential V ₁ ⁺ , and in (0, 0, 1), the transistor 53 is turned on by the NAND 45 to turn off the corrected non-lighting potential V
₃ ⁺ When the polarity is inverted, the transistor 50 is turned on at (42) at (1,1,0) and the lighting potential V ₆ at S (1), and the transistor 51 is turned on at (43) at (0,1,0) and the non-lighting potential. In V ₄ , (1, 0, 0), the transistor 49 is turned on by AND 41 and the corrected lighting potential V
₆ ⁺ , (0,0,0) and transistor 44 at AND 44
2 is turned on, and the correction non-lighting potential V ₄ ⁺ is set.

If the signal F is "1" and T is "1", X
= "1" and Y = "0", which is the potential at the time of non-correction.
At this time, the column electrode signal having the correction potential V _K ⁺ (K = 1, 3, 4, 6) becomes the non-correction potential V _K. If the liquid crystal driving potentials V _K ⁺ and V _K are previously set to the same potential and the signal F is set to “0” and the function is not corrected, both X and Y are “1”.
Transistors 49 and 50, 51 and 52, 53 and 54,
55 and 56 are connected in parallel, and in the state of (Q, P), V
_1, the inner one of the potentials of V _3, V _4, V ₆ is selected.

A circuit 66 similar to the circuit 65 in the first column consisting of 32 to 56 is a circuit in the a-th column, and 67 is a circuit (a + 1) from the image signal sampled at the output C (2) of the shift register. The signal of S (a + 1) is output to the column. V _DD -V _SS is a part of 31 to 39, 40 and 57 to 60
Of the power supply system, the majority of 40 and 41-56, 61
64 operate on the power supply system of V _DD -V _BB .

FIG. 4 is a circuit diagram of flip-flops 33 and 34 for storing image signals used in the drive circuit shown in FIG. When the clock CL is “1”, the clock control type inverter 71 is turned on, the input I is written, and the clock control type inverters 76 and 75 are turned on at the same time.
Hold and output the same image signal as before writing. At this time, the clock control type inverters 73 and 74 are off.
When the clock CL becomes '0', the inverted signal CL of CL ^*
Becomes “1” and the clock control type inverter 71,
76 is turned off, 73 and 74 are turned on, and the image signal written by 73 and the inverter 72 is held.
4 and 75, the image signal Q to be output is updated.

FIG. 5 is a drive circuit diagram on the row side of the image display device of the present invention. Reference numeral 81 denotes a shift register which transfers the vertical start signal _VST using the enable signal LP as a clock and outputs signals D (1), D (2),..., D (b),. . 82 is a level conversion circuit, an input I to shift register output D (1), V _DD
-V _SS is converted to V _DD -V _BB potential level of the signal Q from. Q ^* is an inverted signal of Q.

The polarity inversion signal PO converts from V _DD -V _SS to V _DD -V _BB potential level of the signal at the circuit of 91~93, P and buffer at 94 and 95, the inverted signal of the P P ^* And Selection and non-selection signals Q and Q ^* and polarity signals P and
The two inputs P ^* take ANDs 83 and 84 and NANDs 85 and 86, control the N-channel transistors 87 and 88 and the P-channel transistors 89 and 90, and select the potential from the potential bus V for driving the liquid crystal. One row electrode signal R (1) is output.

Regarding (Q, P), in (1, 1), the transistor 87 is turned on by the AND 83, and R (1) is set to the selection potential V _6, and in (0, 1), the transistor 89 is turned on by the NAND 85, and the selection potential V _2. When the polarity is inverted, the transistor 90 is turned on by the NAND 86 at (1, 0) and the selection potential V ₁ is set to R (1), and the transistor 88 is turned on by the AND 84 at (0, 0) and the non-selection potential V ₅
And Circuits 97 and 98, which are similar to the circuit 96 in the first row consisting of 82 to 90, generate R (2) and R (b) row electrode signals from the outputs of the shift registers in the second and bth rows, respectively. ing. 81, 82 a portion 91 the power supply system of the V _DD -V _SS of, a portion 83～90,92～95 of 82 V _DD -
It operates on the _VBB power supply system.

FIG. 6 is a signal waveform diagram for explaining the operation of the image display device of the present invention shown in FIGS. Signal F
Is a signal T that selects a correction function with '1' and specifies a correction period.
Is always '0'. In synchronization with the timing when the enable signal LP becomes '0' (= V _SS ), the polarity inversion signal PO, the signal M specifying the selection period of one row at the time of polarity inversion, the column electrode signal S (J) in the J column, Row I, (I + 1)
Row electrode signals R (I), R (I +
1), R (I + 2) has changed. The signal R (I) is S
(J) takes the selection potential V ₁ at the time of 104, when the 105 polarity followed is inverted in the non-selection potential V _2, the signal of the next row R
(I + 1) becomes the selection potential V ₆ . At that time, the non-selection potential V
₂ is a signal R (I + 2) is, R (I + 1) non-selection potential V ₂ to become selected in synchronism with the timing potential V _6, and the signal of row electrodes selected pixels in each row, and unselected It is a potential signal.

The image signal S (J) of the column electrode indicated by 101 is the non-selection potential of the row electrode, which is V ₅ and V ₂ in synchronization with the polarity inversion signal PO. When M is “1” and the image signal is inverted with reference to the non-selection potential 101, when 102 to 103 and 106 to 107,
V ₄ ⁺ from each image signal V _6, is under corrected changes from V ₃ ⁺ to V ₁ ^+. 103 to 104 is non-inverting and flows from V ₄ ⁺ in the non-correction potential of V _4. When M changes from “1” to “0” from 107 to 108 and 109 to 110, the image signal is a change between the lighting potential or the non-lighting potential, but the image signal is inverted based on the non-selection potential 101. V ₁ ⁺ to V ₆ ⁺ , V ₄ to V ₃ ⁺
And it is corrected. 104 to 105, 1
11 when from 112 of the image signal lighting - is a change between non-lighting voltage, a non-inverting non-selection potential 101 as a reference, V ₁ from V ₄ respectively, V ₃ ⁺ from the V ₆ non It has changed to the correction potential.

As shown in FIG. 1, when the voltage between the uncorrected image signal potential and the non-selection potential is V, and the voltage between the corrected image signal potential and the non-selection potential is V ⁺ , the image signal is not selected. The image signal voltage is V ⁺ during one horizontal scanning period in which the potential is inverted with reference to the potential, and V in the non-inverted state. Signal T is always '0'
In, before and after the inversion of the image signal, the image signal voltage is passed to V ⁺ from the V or V ^+, at the transition of the non-inverting has changed from V or V ⁺ to V. (V ⁺ -V) is considerably smaller than V, and an image display device having 400 row electrodes
When driving at a frame frequency of 60 Hz, 200
It is adjusted at a voltage within about mV.

FIG. 7 is a signal waveform diagram of a driving method of the image display device according to the present invention, in which the correction potential is set from the time when the image signal changes and the non-correction potential is set in the second half of the selection period of one row of pixels.
The signal F selects a correction function with "1", and the signal T specifying the correction period takes "0" in synchronization with "0" of the enable signal LP, and becomes "1" in the latter half of one horizontal scanning period. I have. Polarity inversion signal PO, image signal S of column electrode of J column
(J) shows a state change similar to FIG. 121 is a change in the non-selection potential of the row electrode.

122 corresponding to 106-107 in FIG.
In 123-124 · 125, it changes to V ₃ ⁺ · V ₃ −V ₁ ⁺ · V _1, and the correction potential is set in the first half 122 and 124 of one horizontal scanning period, and the non-correction potential is set in the second half 123 and 125. , 124-125-12 corresponding to 107-108
6-127 Looking at ^{_{V 1 + · V 1 -V 6}} + · V 6, when the image signal is inverted to non-selection potential as a reference, the image signal voltage is in a change in V ⁺ from V. Since the correction voltage V ⁺ always becomes the non-correction voltage V in the latter half of one horizontal scanning period, it remains at V in the non-inverted transition, and
128.129-130 corresponding to V ₃ ⁺ · V ₃ −V ₆
Has changed.

FIG. 8 shows an image display device according to the present invention. The signal waveform of a driving method in which the non-correction potential is changed after the change of the image signal at the non-correction potential, and the non-correction potential is set before the selection period of the next row is reached. FIG. The signal F is "1", T is "0" in the middle of one horizontal scanning period, and "1" in the front and rear portions. The polarity inversion signal PO and the image signal S (J) of the column electrode in the J-th column show a state change similar to that in FIGS. Reference numeral 131 denotes a change in the non-selection potential of the row electrode. 137 · 13 corresponding to 107
8, 139 changes to V ₁ V ₁ ⁺ V ₁ corresponding to the signal T of "1", "0", "1".

132-133 corresponding to 102-103
At 134, it changes to V ₆ -V ₄ .V ₄ ^+, and 106-10
135, 136-137, 138 corresponding to 7
^{_{3 + · V 3 -V 1,}} V 1 +, 13 corresponding to 107-108
In ^{_{8 · 139-140 · 141 V 1 +}} · V 1 -V 6 · V
₆ ^+, 142-143, 144 corresponding to 109-110
In has changed with the ^{_{V 4 -V 3 · V 3 +}} . When the image signal is inverted with the non-selection potential as a reference, the image signal voltage changes with the non-correction voltage V, and thereafter becomes the correction voltage V ⁺ within the selection period of one row of pixels. The transition of the non-inverted image signal voltage is the same as the non-correction voltage V as in FIG.
145, 146-147 corresponding to -112 is V ₃ ⁺ · V
₃ is a change of -V _6.

[0046]

According to the present invention, in a simple matrix type image display device in which liquid crystal is sandwiched between orthogonal row electrodes and column electrodes, when an image signal applied to a column electrode is inverted with reference to a non-selection potential of the row electrode. Increases the image signal voltage based on the non-selection potential of the column electrode during the period in which the image signal of one row is applied to the column electrode as compared with the case of non-inversion, and changes the polarity of the drive signal applied to the liquid crystal. The AC driving is performed by inverting at the frame cycle.

When the image signal is inverted with reference to the non-selection potential, the waveform corresponding to the drive signal voltage applied to the liquid crystal bends due to the output resistance of the signal, the resistance of the electrode, and the capacitance of the liquid crystal. Pixels with high inversion frequency have lower effective driving voltage than pixels with lower inversion frequency.
In the present invention, when the image signal is inverted, a large corrected image signal voltage is applied to the liquid crystal to reduce the voltage. Lighting pixel,
The driving effective voltage of each non-lighting pixel becomes uniform, and a high-quality image is displayed.

[Brief description of the drawings]

FIG. 1 is a drive signal diagram of a liquid crystal of an image display device of the present invention.

FIG. 2 is a power supply circuit diagram for generating a liquid crystal drive potential of the image display device of the present invention.

FIG. 3 is a drive circuit diagram on the column side of the image display device of the present invention.

FIG. 4 is a circuit diagram of a flip-flop for storing image signals used in the drive circuit shown in FIG.

FIG. 5 is a drive circuit diagram on the row side of the image display device of the present invention.

FIG. 6 is a signal waveform chart for explaining the operation of the image display device of the present invention.

FIG. 7 is a signal waveform diagram of a driving method in the image display device according to the present invention, in which a correction potential is set from a point in time when an image signal changes, and a non-correction potential is set in a second half of a selection period of one row of pixels.

FIG. 8 is a signal waveform diagram of a driving method in the image display device according to the present invention, in which a non-correction potential is used after a change in an image signal at the time of a change, and the correction potential is used before a next row selection period.

FIG. 9 is a configuration diagram of a pixel of a simple matrix type image display device.

FIG. 10 is a screen view of a liquid crystal display for explaining “display unevenness”.

11 (a) is a potential diagram of a signal of a row electrode and lighting and non-lighting of a column electrode, FIG. 11 (b) is a driving signal diagram applied to the liquid crystal on the left half surface 167 of the screen of FIG. 10, and FIG. 10 is a drive signal diagram applied to the liquid crystal in the right half surface 164 of the screen of FIG.

[Explanation of symbols]

V Uncorrected image signal voltage based on non-selection potential V ⁺ Corrected image signal voltage based on non-selection potential V ₁ ⁺ Corrected lighting potential V ₁ Lighting potential and selection potential for V ₅ V ₂ Non-selection potential V ₃ OFF potential V ₃ ⁺ correction OFF potential V ₄ ⁺ V ₃ ⁺ and polarity inversion correction unlit potential V ₄ V ₃ and the polarity reversed unlit potential V ₅ V ₂ and inverted polarity non-selection potential V ₆ V ₁ a polarity reversed lighting potential and the selection potential V ₆ ⁺ V ₁ ⁺ and polarity inversion correction turned potential for V ₂

Continuation of the front page (56) References JP-A-3-179390 (JP, A) JP-A-3-126988 (JP, A) JP-A-2-297586 (JP, A) JP-A-2-89 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G09G 3/00-3/38 G02F 1/133 505-580

Claims (1)

(57) [Claims] 1. A potential signal for sandwiching liquid crystal between a substrate on which a plurality of row electrodes are formed and an opposing substrate on which a plurality of column electrodes are formed, wherein the row electrodes select and deselect pixels for each row. In an image display device which sends an image signal for lighting and non-lighting to a column electrode and inverts the polarity of a driving signal applied to the liquid crystal in a frame cycle and performs AC driving, an image signal applied to a column electrode is a non-selection potential of a row electrode. When inverting with reference to, the liquid crystal is driven by setting the image signal voltage based on the non-selection potential of the column electrode to be higher than in non-inversion during the selection period of one row of pixels. apparatus.