JPH0782166B2 - Liquid crystal display - Google Patents

Description

TECHNICAL FIELD The present invention relates to a matrix display device in which the X axis and the Y axis are crossed in a matrix.

[Outline of Invention]

The present invention relates to a driving method of a thin matrix display device having a built-in nonlinear active element (MSI, MIM, etc.),
The response time is improved by correcting the asymmetry of the IV characteristic of the nonlinear active element (in the positive direction and the negative direction) and making the holding voltage applied to the liquid crystal symmetrical in the positive direction and the negative direction. The purpose is to improve the life of the liquid crystal and display quality.

[Conventional technology]

A conventional matrix display device using liquid crystal employs a drive bias circuit of a voltage averaging method as shown in FIG. That is, by equally dividing V _DD -V _LC by resistors having the same resistance value, the drive voltages in the positive direction and the negative direction applied to the liquid crystal are equalized so that a DC voltage is not applied to the liquid crystal. Is made.

[Problems to be Solved by the Invention]

FIG. 4 is a matrix diagram showing the structure of a matrix display device incorporating a non-linear active element. X ₁ , ~
X ₂ is an X-axis electrode, Y _{1 to} Y ₂ are Y electrodes, LA is a non-linear active element, and LC is a liquid crystal display dot at the intersection. Fifth
The figure is a diagram showing the asymmetry of the IV characteristic of the nonlinear active element. As shown in FIG. 5, comparing the case where a positive direction voltage is supplied to the nonlinear active element from the X electrode side and the case where a negative direction voltage is supplied, the same current flows in the positive direction. It is necessary to increase the voltage. Since the liquid crystal is driven by the non-linear active element to display the liquid crystal by holding the charge amount charged by this current, it is important to make the liquid crystal symmetrical. What happens is that the same voltage in the positive and negative directions
It can be understood that the holding time of the charge amount varies depending on the voltages in the positive direction and the negative direction because the impedances in the positive direction and the negative direction are different when applied to the nonlinear active element. That is, there is a problem that striping display (horizontal stripe) is generated when the display blinking operation is performed due to the difference in the fall time at which the display disappears. Further, when excessive electric charge is accumulated and the display is erased, charge-up occurs and it takes a long time until the display disappears, which causes a problem in display quality.

[Means for Solving the Problems]

In order to solve the above problems, the present invention relates to a driving method of a liquid crystal display device having a built-in nonlinear active element, the method including X-
The drive voltage applied to one electrode of the Y electrode is different from the drive voltage supplied to the other electrode in the direction that corrects the positive and negative asymmetry of the nonlinear active element, and X- The intersection of the Y electrodes is driven by alternating current.

[Action]

One example of the driving system of the present invention is the bias voltage generating circuit shown in FIG. In FIG. 1, 6 to 10 are resistors for bias voltage division. Reference numerals 1 to 5 denote operational amplifier circuits. V _DD is + 5V and V _LC is the liquid crystal driving negative power supply. V ₀₁ and V ₀₂ respectively indicate positive selection voltages of the X electrode and the Y electrode. V ₅ indicates the selection voltage in the negative direction. V _{1 to} V ₄ indicate bias voltages when not selected. Here, assuming that the resistance value of the resistor 8 is 1.0R, the resistance values of 6, 7, 9, and 10 are 1.5R, 0.5R, 1.5R, and 0.5R, respectively. Further, 6 is composed of a variable resistor, and the midpoint voltage thereof is amplified by the operational amplifier circuit 1. Therefore, it can be understood that the positive selection voltage V ₀₂ applied to the Y electrode is lower than the positive selection voltage V ₀₁ applied to the X electrode. Also, the voltage difference between V ₀₁ -V ₁ and V ₃ -V ₄ increases due to the voltage difference between V ₂ -V ₃ , while V ₁ -V _1
2 , the voltage difference between V _{4 and} V ₅ is smaller than the voltage difference between V _{2 and} V ₃ . That is, the bias voltage is not divided evenly, but is divided unevenly. This is to correct the asymmetry of the above-mentioned nonlinear active element.

〔Example〕

FIG. 3 is a diagram showing an example of the drive waveforms of the present invention. FIG. 3 shows an example of drive waveforms when 1-dot display and non-display are repeated for each line.
M indicates a polarity inversion signal for each frame, and DFM indicates a polarity inversion signal for every two lines. Y ₁ and X ₁ are the Y electrode and X, respectively
The drive waveform applied to the electrodes is shown. and again,
Y ₁ -X ₁ shows a driving voltage waveform to be applied to the liquid crystal at the intersection of Y ₁ -X _1. As shown, Y ₁ −X ₁
It can be understood that the drive waveform between the two is shifted to the X ₁ electrode side as a whole, and a positive voltage is applied to the X electrode side and a larger voltage is applied to the negative electrode voltage. Further, the selection voltage V ₀₂ applied in the positive direction of the Y electrode can be arbitrarily set by the variable resistor 6. As a result, the positive-direction voltage at the time of selecting the intersection of the X electrode and the Y electrode can be arbitrarily set independently of the voltage that shifts as a whole. Therefore, by applying a larger voltage to the X electrode side so as to correct the asymmetry of the non-linear active element, it becomes possible to flow the same charging current in voltage driving in the positive direction and the negative direction. Therefore, the correction can be performed so as to hold the same charge.

〔The invention's effect〕

As described above, according to the present invention, in order to correct the non-linearity of the non-linear active element by the driving voltage, the striping problem that has been a conventional problem, that is, the driving voltage in the positive direction or the negative direction is displayed. However, the problem is that the difference in the fall response time when it is hidden and the difference of about 2 to 10 ms are striping, but the uniform fall is caused by changing the resistance value and adjusting the variable resistance value. We had time to solve this problem.
Further, the charge-up problem that the non-lighting time becomes long due to the excessive accumulated charge amount and the display does not disappear easily can be solved. Further, the liquid crystal at the intersection of the X-axis and the Y-axis is driven by an alternating current having substantially no direct-current component, so that it has a great effect that the life of the liquid crystal can be extended as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a conventional bias circuit diagram, FIG. 3 is a diagram showing an embodiment of a drive waveform of the present invention, and FIG. 4 is a nonlinear active element. FIG. 5 is a matrix diagram showing the structure of the built-in matrix display device, and FIG. 5 is a diagram showing the asymmetry of the IV characteristic of the nonlinear active element. 1 to 5 ... Operational amplifier circuit 6 to 10 ... Dividing resistor for bias voltage LA ... Non-linear active element LC ... Liquid crystal

Claims (2)

[Claims] 1. A display pixel is formed at an intersection of a matrix of X electrodes and Y electrodes, and a non-linear resistance element having asymmetric current-voltage characteristics and a liquid crystal are electrically connected to the display pixels. The voltage levels applied to the X electrode and the Y electrode are serially connected to each other, and the ratio thereof is determined by resistance division of a bias circuit. The Y electrode is selectively frame-scanned, and the voltage level depends on the potential difference between the X electrode and the Y electrode. In the display device in which the composite voltage is applied to the display pixels to operate, the polarities of the composite voltage of the first frame scan and the composite voltage of the second frame scan are reversed, and the non-selection of the first frame scan and the second frame scan is performed. The average of the combined voltage of the period includes the first DC component of one polarity, and the first frame scan and the second frame
The average of the combined voltage in the selection period of the frame scan includes the second DC component of one polarity, and the bias circuit independently sets the voltage level of the first DC component and the voltage level of the second DC component to each other. A display device having means for performing setting. 2. The display device according to claim 1, wherein the bias circuit has at least five resistors in which resistors R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are connected in series. The voltage levels V ₀₁ and V ₅ at both ends are divided by the above resistors to form R ₁
And between R _2, is R ₂ and between R _3, R ₃ and each of the voltage levels between R ₄ is _{V 1, V 2, V 3} , V 4, and, R ₁ is located at a variable resistor , The potential level from the midpoint of the variable resistor is V ₀₂ , and in the first frame scan, the voltage levels in the selection period and the non-selection period of the Y electrode are V ₀₂ and V ₄ , respectively, and the selection of the X electrode is The voltage levels in the period and the non-selection period are V ₅ and V ₃ , respectively, and in the second frame scan, the voltage levels in the selection period and the non-selection period of the Y electrode are V ₅ and V ₁ , respectively, and the selection of the X electrode is The voltage levels in the period and the non-selected period are V ₀₁ and V ₂ , respectively, and the means provides the first DC component by setting the resistance R ₄ larger than the resistance R ₂ , and the variable resistance R 1
The display device is characterized in that the second DC component is independently given to the setting of the first DC component by arbitrarily setting the intermediate point of.