JP3612947B2 - Method for driving liquid crystal display device and liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device driving method and a liquid crystal display device driving device for driving a liquid crystal display device in a communication terminal such as a mobile phone, an electronic notebook, and a display device. The present invention relates to a driving method of a liquid crystal display device and a liquid crystal display device capable of correcting contrast characteristics of the liquid crystal display device provided.
[0002]
[Prior art]
For example, as a display device using a liquid crystal display device provided with a two-terminal nonlinear resistance element such as an MIM (Metal-Insulator-Metal) element, a display device having the structure shown in FIG. 6 is conventionally known. The display device 10 shown in the figure includes X drivers 12 and 12 that output a signal line side signal to the signal line side electrode of the transmissive liquid crystal panel 11, and a reverse selection negative voltage signal and a positive selection positive voltage applied to the scanning line side electrode. Y drivers 13 and 13 for outputting a scanning line side signal composed of a set of signals are provided.
[0003]
In this display device 10, when the arrangement of the liquid crystal elements at a predetermined portion of the liquid crystal panel 11 is changed and displayed in black, the Y driver 13 moves the liquid crystal elements as shown on the left side of FIG. For example, in the first half period of one horizontal period (1H), the negative selection negative voltage signal 21 of −25V is output to all the scanning line side electrodes in the row direction, and in the second half period of one horizontal period (1H), for example, , 30V positive selection positive voltage signal 22 is output. At this time, the X driver 12 outputs a signal line side signal 23 of 0 V, for example, as shown on the left side of FIG. As a result, the scanning line side signal and the signal line side signal are applied to both ends of the MIM element, and the voltage difference between both ends exceeds the operating voltage of the MIM element. When it is driven to the state, black is displayed.
[0004]
On the other hand, when displaying in white without changing the arrangement state of the liquid crystal elements, as shown on the right side of FIG. 5A, the Y driver 13 performs one horizontal period (1H) with respect to the scanning line side electrode. In the first half period, for example, a negative selection negative voltage signal 24 of −30 V is output, and in the second half period of one horizontal period (1H), for example, a positive selection positive voltage signal 25 of 25 V is output. At this time, the X driver 12 outputs a signal line side signal 26 of 5 V, for example, as shown on the right side of FIG. In this case, since the voltage difference between both ends of the MIM element does not exceed the operating voltage, the liquid crystal element displays a white color as a result of maintaining the transmission state without changing the arrangement. Thus, in this display device 10, the Y drivers 13 and 13 drive the liquid crystal panel 11 by outputting a scanning line side signal having a 50% duty ratio in one horizontal period. Further, the Y driver 13 is driven by the scanning line side signal composed of the reverse selection negative voltage signal and the positive selection positive voltage signal, so that the Y driver 13 is driven by the scanning line side signal of the positive voltage. It is possible to improve the contrast ratio.
[0005]
[Problems to be solved by the invention]
However, this conventional display device 10 has the following problems.
[0006]
That is, the I / V characteristics (hereinafter also simply referred to as “I / V characteristics”) in the pool-Frenkel plot of the MIM type liquid crystal panel, as shown in FIG. The I / V characteristic C1 having a normal value of (I / V) has two types of variations of the I / V characteristic C2 and the I / V characteristic C3 shown in FIG. Exists. Specifically, the I / V characteristic C2 has a slope β of the value of log (I / V) with respect to the drive voltage V (tan-1 ((m3−m4) / (10V−4V)) in the figure). The on-resistance of the MIM element has the I / V characteristic C1, although it is the same as the slope β of the I / V characteristic C1 (in the figure, tan-1 ((m1-m2) / (10V-4V))). Since the resistance is higher or lower than that of the MIM element, the characteristics are translated along the drive voltage axis. On the other hand, the slope of the I / V characteristic C3 (in the figure, tan-1 ((m5−m6) / (10V−4V)) itself is different from the normal I / V characteristic C1.
[0007]
Here, when the MIM type liquid crystal panel has the I / V characteristic C2, for example, a volume for changing the drive voltage of the scanning line side signal is arranged in the display device 10, and the volume is adjusted. Therefore, it is possible to set the contrast substantially the same as the normal I / V characteristic C1.
[0008]
However, the MIM type liquid crystal panel having the I / V characteristic C3 cannot be set to the same contrast as the normal I / V characteristic C1 even if the drive voltage of the scanning line side signal is varied. That is, as shown in FIG. 5, in the contrast characteristic CR1 of the MIM type liquid crystal panel having the I / V characteristic C1, for example, when the scanning line side signal is the voltage V0, the value is (b11 / a11). In the contrast characteristic CR3 of the MIM type liquid crystal panel having the I / V characteristic C3, the value is (b12 / a12) when the scanning line side signal is the voltage V0. In this case, even if the drive voltage of the scanning line side signal is varied depending on the volume, the contrast characteristic has a different slope, so it cannot be made the same as the contrast characteristic CR1 of the MIM type liquid crystal panel having the I / V characteristic C1. As a result, the conventional display device 10 has a problem that it is difficult to maintain a constant quality including its contrast characteristics.
[0009]
Further, for example, when the luminance of the liquid crystal panel 11 is changed to a plurality of gradations by performing pulse width modulation on the signal line side signal, for example, when the drive voltage of the scanning line side signal is a value V0, the contrast characteristic CR1 has the luminance. Is the value (b11), whereas the brightness of the contrast characteristic CR3 is the value (b12). For this reason, there is a problem that the set luminance gradation is different from the actual luminance gradation. In this case, when a full-color liquid crystal display device is configured with three colors of red, green, and blue (hereinafter also referred to as “RGB”), the luminance gradation of each of the three RGB colors is different. There is also a problem that the color is different.
[0010]
The present invention has been made to remedy such problems, and a liquid crystal display device capable of making the contrast characteristics of a liquid crystal display device uniform due to a characteristic error or a manufacturing error of a two-terminal nonlinear resistance element. The main object is to provide a driving method and a liquid crystal display device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a driving method of a liquid crystal display device according to claim 1, wherein the signal line side signal is output to the signal line side electrode, and the reverse selection negative voltage signal and the positive selection positive voltage signal are output to the scanning line side electrode. In a driving method of a liquid crystal display device including a two-terminal nonlinear resistance element that outputs a scanning line side signal composed of a set, by varying a duty ratio between the reverse selection negative voltage signal and the positive selection positive voltage signal The contrast characteristic of the liquid crystal display device is corrected.
[0012]
In this driving method of the liquid crystal display device, when the I / V characteristic of the liquid crystal display device to be driven is different from that of a normal liquid crystal display device having the I / V characteristic C1, the reverse selection negative voltage of the scanning line side signal The duty ratio between the signal and the positive selection positive voltage signal is varied. In this case, if the duty ratio of the positive selection positive voltage signal changes, the response of a two-terminal nonlinear resistance element such as an MIM element (hereinafter, described by taking the MIM element as an example) for the positive selection positive voltage signal Characteristics can be changed. That is, it is possible to control the slope β in the I / V characteristic of the MIM element by changing the duty ratio of the positive selection positive voltage signal. Therefore, the I / V characteristic that varies due to the characteristic error or the manufacturing error of the MIM element can be arbitrarily corrected. As a result, the contrast characteristic of the liquid crystal display device can be made uniform.
[0013]
The method for driving a liquid crystal display device according to claim 2 is the method for driving a liquid crystal display device according to claim 1, wherein the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal line side signal. And
[0014]
In this liquid crystal display device driving method, the luminance gradation of the liquid crystal display device is controlled by performing pulse width modulation on the signal pulse width of the signal line side signal. In this case, the I / V characteristics of the MIM element can be made uniform, and as a result, the set luminance gradation and the actual luminance gradation always coincide. Moreover, even when the full color is formed using the three colors of RGB, the set color and the actually displayed color always coincide with each other, so that the display color can be made uniform.
[0015]
The method for driving a liquid crystal display device according to claim 3 is the method for driving a liquid crystal display device according to claim 1 or 2, wherein at least one of the minimum value of the reverse selection negative voltage signal and the maximum value of the positive selection positive voltage signal is corrected. Thus, the contrast characteristic of the liquid crystal display device is corrected.
[0016]
The contrast characteristic can be corrected by changing the duty ratio of the positive selection positive voltage signal in the scanning line side signal, but the contrast value for the driving voltage of the scanning line side signal is not automatically equalized. . In such a case, the display device that adjusts the contrast by changing the drive voltage of the scanning line side signal using the adjustment volume uses a liquid crystal display device that originally has normal I / V characteristics, and I / V. When using the liquid crystal display device with corrected characteristics, the rotational positions of the volumes are different from each other when the same contrast is set. In this liquid crystal display device driving method, at least one of the minimum value of the reverse selection negative voltage signal and the maximum value of the positive selection positive voltage signal of the scanning line side signal is corrected, so that the contrast characteristic with respect to the rotational position of the volume is adjusted. It becomes possible to make uniform.
[0017]
According to a fourth aspect of the present invention, there is provided a liquid crystal display device including a driving unit that generates and outputs the signal line side signal and the scanning line side signal according to the driving method of the liquid crystal display device according to any one of the first to third aspects. It is characterized by.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a liquid crystal display device driving method and a liquid crystal display device according to preferred embodiments of the invention will be described with reference to the accompanying drawings. The display device 1 using the liquid crystal display device has a driving method different from that of the conventional display device 10 shown in FIG. 6, but the configuration itself is the same. Therefore, the liquid crystal display device according to the present invention is described with reference to FIG. A method of driving the liquid crystal panel 11 by the X driver 12 and the Y driver 13 corresponding to the driving means will be described in detail.
[0019]
The essential feature of the display device 1 according to this embodiment is that the reverse selection negative voltage signal 31 and the positive selection positive voltage signal 32 of the scanning line side signal are shown in FIG. The duty ratio is variable.
[0020]
Hereinafter, a driving method of the liquid crystal panel 11 when the inclination β of the I / V characteristic in the liquid crystal panel 11 is different from the normal I / V characteristic will be described with reference to FIGS.
[0021]
FIG. 3A shows the contrast characteristic CR11 when it is assumed that the slope β in the I / V characteristic of each MIM element of the liquid crystal panel 11 is, for example, a normal value 4.0. In the figure, the Y axis indicates the transmittance, and the X axis indicates the scanning line side signal voltage. Further, in the contrast characteristic CR11, the duty ratio of the positive selection positive voltage signal to the signal width of the scanning line side signal output from the Y driver 13 is approximately 50%, that is, the positive selection positive voltage signal 32, FIG. In the state where the pulse width of 32 (hereinafter referred to as “pulse width w”) is set to 30 μS, which is about 1 / 2H, the luminance at the time of driving the signal line side signal of the on signal and the off signal from the X driver 12 A characteristic 41 and a non-driving luminance characteristic 42 are shown. In this contrast characteristic CR11, for example, when the drive voltage of the scanning line side signal is the value V1, the contrast value (b1 / a1) is obtained.
[0022]
On the other hand, if the value of the slope β in the I / V characteristic for each MIM element of the liquid crystal panel 11 varies in an increasing direction, for example, 5.0, the liquid crystal panel 11 has the contrast characteristic CR12 shown in FIG. doing. In this case, the contrast when the drive voltage of the scanning line side signal is the value V1 is a value (b2 / a2), which is different from the contrast characteristic CR11. Further, in the contrast characteristic CR12, the change in contrast with respect to the drive voltage of the scanning line side signal is also a characteristic that changes sharply. In such a case, even if the drive voltage of the scanning line side signal is varied, the contrast characteristic CR12 cannot be made the same as the contrast characteristic CR11.
[0023]
In such a case, in the display device 1 according to this embodiment, as shown in FIG. 1, the pulse width w of the positive selection positive voltage signal 32 in the scanning line side signal output from the Y driver 13 is, for example, 10 μS. Set. As a result, the response of the MIM element to the positive selection positive voltage signal 32 in the liquid crystal panel 11 is slowed down. As a result, the slope β in the I / V characteristic is reduced, whereby the liquid crystal panel 11 is shown in FIG. It has a contrast characteristic CR13. In this contrast characteristic CR13, the contrast when the drive voltage of the scanning line side signal is the value V2 is the value (b1 / a1), and the contrast characteristic CR11 in FIG. Become. That is, the liquid crystal panel 11 has a characteristic that the followability of the transmittance change of the liquid crystal element with respect to the positive selection positive voltage signal 32 tends to decrease.
[0024]
Therefore, by providing a contrast adjustment volume in the display device 1 and changing the volume to vary the drive voltage of the scanning line side signal, the contrast characteristic CR11 shown in FIG. The same contrast characteristic can be corrected.
[0025]
Further, in this case, as shown in FIG. 2, if the drive voltage of the positive selection positive voltage signal 33 is set to a high voltage, the contrast characteristic with respect to the rotation position of the contrast adjustment volume is shown in FIG. It can be made the same as the contrast characteristic CR11. That is, if the drive voltage of the scanning line side signal is corrected, the contrast characteristic CR13 in FIG. 9C is translated along the driving voltage axis of the scanning line side signal. Therefore, for example, in the display device 1 using the liquid crystal panel 11 having the contrast characteristic CR11, the rotation position of the volume where the drive voltage of the scanning line signal becomes the value V1 and scanning in the display device 1 using the liquid crystal panel 11 having the contrast characteristic CR13. If the maximum value of the drive voltage of the positive selection positive voltage signal 33 is corrected so that the rotational position of the volume at which the drive voltage of the line signal is the value V1 is the same position, the volume of the liquid crystal panel 11 of the contrast characteristic CR13 is corrected. The contrast characteristic with respect to the rotational position apparently shifts to the contrast characteristic CR4 shown in FIG. Therefore, the contrast value with respect to the rotational position of the volume can be made uniform.
[0026]
Further, even when the luminance gradation of the liquid crystal panel 11 is controlled by stepwise changing the pulse width of the signal line side signal 26 shown in FIG. 7B, the contrast characteristics of the liquid crystal panel 11 are made uniform. As a result, the set luminance gradation and the actual luminance gradation can always be matched. Therefore, even when a full-color two-terminal liquid crystal display device is configured using RGB three-color filters, the set color can be always matched with the actually displayed color.
[0027]
As described above, according to the display device 1 according to this embodiment, the variation in the contrast characteristic due to the variation in the I / V characteristic of the MIM element caused by the characteristic error of the MIM element itself or the manufacturing error. Can be easily corrected by changing the pulse width w. Even when the contrast is adjusted by the contrast adjusting volume, the contrast characteristic with respect to the rotational position of the volume can be made uniform by correcting the drive voltage of the positive selection positive voltage signal.
[0028]
The present invention is not limited to the above-described embodiment. For example, the driving voltage of the signal line side signal and the driving voltage of the scanning line side signal respectively output from the X driver 12 and the Y driver 13 can be set to the most appropriate voltage according to the characteristics of the liquid crystal panel 11. In addition, in the present embodiment, the duty ratio of the positive selection positive voltage signal with respect to the signal width of the scanning line side signal has been described as an example in which the duty ratio is reduced. However, the liquid crystal display device driving method and the liquid crystal display apparatus according to the present invention have been described. Then, the duty ratio may be increased in accordance with the contrast characteristics of the liquid crystal panel 11. Further, it is possible to employ a configuration in which a switch or a volume for setting the duty ratio is provided, and the Y driver 13 is controlled so as to have a duty ratio set by the switch.
[0029]
In this embodiment, the contrast characteristic is corrected by changing the pulse width w of the scanning line side signal output from the Y driver 13, but the driving voltage of the signal line side signal of the X driver 12 is also changed. You may make it change in steps. In such a case, the contrast characteristic of the liquid crystal panel 11 can be controlled to an arbitrary characteristic.
[0030]
In the present embodiment, the two-terminal nonlinear resistance element has been described by taking the MIM element as an example. However, the present invention is not limited to this, and is a two-terminal element having a conductor-insulator-conductor structure. Any material that exhibits non-linear resistance characteristics may be used.
[0031]
Furthermore, in the present embodiment, an example of driving while correcting the contrast characteristics of the transmissive liquid crystal panel 11 has been described. However, the driving method of the liquid crystal display device according to the present invention is also applied to a reflective liquid crystal display device. be able to.
[0032]
In addition, the liquid crystal display device driving method and the liquid crystal display device according to the present invention can be suitably used for electronic devices and information devices such as mobile phones, electronic notebooks, personal computers, and liquid crystal televisions.
[0033]
【The invention's effect】
As described above, according to the driving method of the liquid crystal display device according to claim 1, the two-terminal nonlinear resistance is obtained by changing the duty ratio between the reverse selection negative voltage signal and the positive selection positive voltage signal in the scanning line side signal. I / V characteristics that vary due to element characteristic errors, manufacturing errors, and the like can be corrected uniformly, whereby the contrast characteristics of the liquid crystal display device can be made uniform.
[0034]
According to the method for driving a liquid crystal display device according to claim 2, when the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal line side signal, the I / O of the two-terminal nonlinear resistance element is used. As a result of making the V characteristic uniform, the set luminance gradation and the actual luminance gradation can always be matched. In addition, even when the full color is formed using the three colors of RGB, the set color and the actually displayed color always coincide with each other, so that the display color can be made uniform.
[0035]
Further, according to the driving method of the liquid crystal display device according to claim 3, the adjustment is performed by correcting at least one of the minimum value of the reverse selection negative voltage signal and the maximum value of the positive selection positive voltage signal in the scanning line side signal. Even when the contrast is adjusted by the volume or the like, the contrast characteristic with respect to the rotation position of the adjustment volume can be made uniform.
[0036]
According to the liquid crystal display device of the fourth aspect of the present invention, the two-terminal type non-linearity is provided by providing the driving means for changing the duty ratio between the reverse selection negative voltage signal and the positive selection positive voltage signal in the scanning line side signal. The I / V characteristics that vary due to errors in the characteristics of the resistive elements, manufacturing errors, and the like can be corrected uniformly, whereby the contrast characteristics of the liquid crystal display device can be made uniform. In addition, since the I / V characteristics of the two-terminal nonlinear resistance element can be made uniform, the set luminance gradation and the actual luminance gradation can always be matched. Further, even when the full color is made using the three colors of RGB, the set color and the actually displayed color always coincide with each other, so that the display color can be made uniform. In addition, by adjusting at least one of the minimum value of the negative selection negative voltage signal and the maximum value of the positive selection positive voltage signal in the scanning line side signal, the adjustment can be performed even when adjusting the contrast using an adjustment volume. The contrast characteristics with respect to the rotational position of the volume for use can be made uniform.
[Brief description of the drawings]
FIG. 1 is a signal waveform diagram of a scanning line side signal output from a Y driver in a display device according to an embodiment of the present invention.
FIG. 2 is another signal waveform diagram of a scanning line side signal output from a Y driver in the display device according to the embodiment of the present invention.
3A is a characteristic diagram of a contrast characteristic CR11, FIG. 3B is a characteristic chart of a contrast characteristic CR12, FIG. 3C is a characteristic chart of a contrast characteristic CR13, and FIG. 3D is a contrast characteristic CR4; FIG.
FIG. 4 is a characteristic diagram showing I / V characteristics in a pool Frenkel plot for a liquid crystal display device to be driven.
FIG. 5 is a contrast characteristic diagram for explaining an example in which contrast characteristics differ due to differences in I / V characteristics.
FIG. 6 is a block diagram of a conventional display device and a display device according to the present embodiment.
7A is a signal waveform diagram of a scanning line side signal output from a Y driver in a conventional display device, and FIG. 7B is a signal waveform side signal output from an X driver in a conventional display device. It is a signal waveform diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Display apparatus 11 Liquid crystal panel 12 X driver 13 Y driver 31 Reverse selection negative voltage signal 32 Positive selection positive voltage signal

Claims (4)

A two-terminal nonlinear resistance element that outputs a signal line side signal to the signal line side electrode and outputs a scanning line side signal composed of a set of a reverse selection negative voltage signal and a positive selection positive voltage signal to the scanning line side electrode is provided. In the driving method of the liquid crystal display device,
A method of driving a liquid crystal display device, comprising: correcting a contrast characteristic of the liquid crystal display device by varying a duty ratio between the reverse selection negative voltage signal and the positive selection positive voltage signal. 2. The driving method of a liquid crystal display device according to claim 1, wherein the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal line side signal. 3. The liquid crystal according to claim 1, wherein the contrast characteristic of the liquid crystal display device is corrected by correcting at least one of a minimum value of the reverse selection negative voltage signal and a maximum value of the positive selection positive voltage signal. A driving method of a display device. 4. A liquid crystal display device comprising drive means for generating and outputting the signal line side signal and the scanning line side signal according to the liquid crystal display device driving method according to claim 1. .

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