JPH09222593A - Liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device capable of minimally suppressing a disparity in brightness of an image caused by a change of a drive signal. SOLUTION: The drive signal supplied to a drive electrode of a liquid crystal element 21 by a drive control circuit 41 for driving a liquid crystal filled up between substrates is changed by an adjustment volume 45, and the disparity in the brightness of the display image caused by the change of the drive signal is compensated by an image conversion control means 44. That is, the image conversion control means 44 is provided with a variable amount detection part 44a detecting a variable amount in the drive signal, and compensates the disparity in the brightness of the image by outputting a compensation signal answering to a detective signal from the variable amount detection part 44a to an image conversion circuit 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device for displaying characters and images, and more particularly to a liquid crystal device adapted to adjust a display image by changing a drive signal.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal device for displaying an image by driving a liquid crystal (compound) filled between substrates on which a matrix electrode having a scan electrode group and an information electrode group is formed is well known. ing. Among them, a liquid crystal device using a ferroelectric liquid crystal having bistability and having a quick response to an electric field is expected as a high-speed and memory type display device. It is proposed in Japanese Patent Laid-Open No. 107216.

By the way, when image information is displayed by such a liquid crystal device, the drive voltage applied to the drive electrodes is changed by adjusting the drive voltage, for example, by manually operating the adjustment knob to adjust the display image. Those who do are widely known.

[0004]

However, in such a conventional liquid crystal device, when the drive signal is adjusted by the adjusting volume or the like, the range in which good ON / OFF can be displayed can be adjusted, but the other ranges can be adjusted. Since it is difficult to make a good adjustment, there is a problem that a difference in brightness of displayed images occurs and the overall contrast changes.

Therefore, the present invention has been made in order to solve such a problem, and it is an object of the present invention to provide a liquid crystal device capable of minimizing the difference in image brightness caused by a change in drive signal. To aim.

[0006]

SUMMARY OF THE INVENTION The present invention is a liquid crystal device for displaying an image by driving a liquid crystal filled between substrates with a drive signal applied to a drive electrode. A driving signal supplying means for supplying the driving signal; a driving signal changing means for changing the driving signal; and a compensating means for compensating for a difference in brightness of a display image caused by a change in the driving signal by the driving signal changing means. It is characterized by that.

According to the present invention, the compensating means includes a change amount detecting section for detecting a change amount of the drive signal, and compensates for a difference in brightness of the display image according to a detection signal from the change amount detecting section. The compensation signal is output to the drive signal supply means.

Further, the present invention is characterized in that the compensating means outputs the compensation signal based on a table showing the relationship between the variation amount of the drive signal and the compensation signal corresponding to the variation amount. Is.

The present invention is also characterized in that the drive signal changing means changes the drive signal by a manual operation.

The present invention is also characterized in that the drive signal changing means is an adjusting knob.

The present invention is also characterized in that the drive signal changing means changes the drive voltage of the drive signal.

Further, the present invention is characterized in that the drive signal changing means changes the frequency of the drive signal.

Further, the present invention is characterized in that the drive electrode is a matrix electrode having a scan electrode group and an information electrode group.

The present invention is also characterized in that the liquid crystal is a ferroelectric liquid crystal. Further, the present invention is characterized in that the liquid crystal is a chiral smectic liquid crystal.

With this configuration, the drive signal supplied to the drive electrodes by the drive signal supply means for driving the liquid crystal filled between the substrates is changed by the drive signal changing means and is compensated. The means compensates the difference in brightness of the display image caused by the change of the drive signal.

That is, the compensating means is provided with a change amount detecting section for detecting the change amount of the drive signal, and the compensating signal is outputted to the drive signal supplying means in accordance with the detection signal from the change amount detecting section, whereby the image To compensate for the difference in brightness.

Further, the compensating means includes a variation amount of the drive signal,
The compensation signal is output based on a table showing the relationship with the compensation signal corresponding to the amount of change.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a liquid crystal device according to the present invention. In FIG. 1, 1 is a liquid crystal device. The liquid crystal device 1 has a transmissive display unit 2, a backlight unit 3 for illuminating the display unit 2, and a drive unit 4 for driving the display unit 2.

Here, the display unit 2 includes a liquid crystal element 21.
And an information signal applying circuit 22 and a scanning signal applying circuit 23 for driving the same. Further, the liquid crystal element 21 is provided with a pair of glass substrates 4a and 4b which are arranged opposite to each other as shown in FIG. 2, and the polarizing plates 3a and 3b are attached to the outside of these glass substrates 4a and 4b. ing. Further, the light shielding metal 7, the color filter 8 and the planarizing resin 14 are provided on the one glass substrate 4b.

Further, a scanning electrode group 5A composed of the ITO electrode 5a and the metal electrode 6a and an information electrode group 5B composed of the ITO electrode 5b and the metal electrode 6b are respectively formed between the glass substrates 4a and 4b. Here, each of these electrode groups forms a matrix electrode which is a drive electrode and is covered with insulating films 13a and 13b. The insulating films 13a and 13b are further aligned with the alignment films 9a and 9b.
It is covered by b. Spacer beads 10 and an adhesive 11 are arranged between these substrates (more precisely, between the alignment films 9a and 9b), and the spacer beads 10 and the adhesive 11 cause a gap between the substrates 4a and 4b. Is configured to keep constant.

A ferroelectric liquid crystal (for example, a chiral smectic liquid crystal) 12 is filled between the substrates 4a and 4b. The ferroelectric liquid crystal 12 is applied to the scanning electrode group and the information electrode group. The optical stable state is changed according to the voltage (hereinafter, referred to as drive voltage) to display predetermined information. Further, the ferroelectric liquid crystal 12 has a memory effect of holding its stable state even when a drive voltage is not applied. The physical properties of the ferroelectric liquid crystal 12 are as shown in the table of FIG.

On the other hand, the backlight unit 3 includes a backlight device 31, an inverter 32 for applying a voltage to the backlight device 31, and a backlight device 3 as shown in FIG.
1 and the dimming control circuit 33 for adjusting the brightness.
Here, the dimming control circuit 33 outputs a dimming control signal to the inverter 32, and the inverter 3
2 is a backlight device 31 according to the dimming control signal.
The voltage applied to the backlight device 31 is changed, whereby the brightness of the backlight device 31 is adjusted.

The backlight device 31 is shown in FIG.
A liquid crystal device 1 containing a display unit 2 as shown in FIG.
Of the fluorescent lamp 34, the light guide plate 35, the reflecting plate 36, and the diffusing plate 3 which are arranged on the inner side of the casing 1A.
7 is provided. Here, this backlight device 31
Guides the light from the fluorescent lamp 34 to the light guide plate 35 and the reflection plate 3.
After being reflected by 6, the display unit 2 is illuminated with uniform brightness by diffusing by the diffusion plate 37. An opening 1B is formed in the upper part of the housing 1A, and a display board 1C is arranged in the opening 1B.

On the other hand, the drive section 4 has a drive control circuit 41 and a graphic controller 42 for storing image information as shown in FIG. 1, and the image information from the graphic controller 42 is sent to an image conversion circuit 43. After being converted into image conversion data, it is supplied to the drive control circuit 41.

Then, the image conversion data is converted into a scanning signal and an information signal by the drive control circuit 41, and then the scanning electrode group 5A is passed through the scanning signal applying circuit 23 and the information signal applying circuit 22 of the display unit 2. And to the information electrode group 5B. The drive control circuit 41, the graphic controller 42, and the image conversion circuit 43 constitute a drive signal supply means.

In the figure, reference numeral 44 is connected to the image conversion circuit 43, and controls the expansion of the contrast of the liquid crystal element 21 or vice versa (hereinafter referred to as the contrast / enhancement function) to reduce the difference in brightness of the displayed images. It is an image conversion control circuit which is a compensating means for compensating.

Here, the contrast / enhancement function is a linear modification and is uniquely applied to the red, green, and blue elements. It is configured to shift all colors towards the corners of the entire input, increasing the contrast between near black and near white regions.

The contrast expansion is realized by changing the value loaded in the look-up table of the color rendering table look-up unit (not shown) provided in the image conversion circuit 43. Specifically, the linear multiplication coefficient h is applied to each of the R, G, and B values of each sample according to the following relational expression.

R _OUT = [(R _in −128) * (256 / h)] + 128 G _OUT = [(G _in −128) * (256 / h)] + 128 B _OUT = [(B _in −128) * (256 / h)] + 128 where h is an integer in the range of 1 to 256. h = 1,
FIG. 5 shows the relationship when 64, 128, and 256.

By the way, as shown in FIG. 1, the image conversion control circuit 44 is connected to an adjusting volume 45 which is a drive signal changing means manually operated by an operator and which is an example of an adjusting knob. Here, the adjustment volume 45 is for changing a drive signal, in the present embodiment, a drive voltage in accordance with an adjustment signal given as an integer value of 0 to 255, for example.

By the way, when the drive voltage is changed by the adjusting volume 45, the brightness is reduced due to the voltage characteristic of the liquid crystal element 21, so that a difference in brightness occurs on the display surface 1C. Therefore, in order to compensate for the difference in brightness, in the present invention, the image conversion control circuit 44 is provided with the adjusting volume 4.
Change amount detecting section 44a for detecting the change amount of the drive voltage by monitoring the adjustment signal input from the drive control circuit 41 to the drive control circuit 41.
And outputs a detection signal detected by the change amount detection unit 44a, that is, a contrast control signal, which is a compensation signal so as to automatically set the contrast / enhancement function in accordance with a change in drive voltage, to the image conversion circuit 43. I am trying to do it.

Here, this contrast control signal changes the multiplication coefficient h of the look-up table provided in the image conversion circuit 43, and thus the multiplication coefficient h is changed according to the change of the driving voltage. By changing the difference, it is possible to compensate for the difference in the brightness of the display image, and to keep the difference in the brightness of the image before and after the adjustment of the drive signal to a minimum.

The image conversion circuit 43, which receives the contrast control signal, carries out image conversion of the display data having a size corresponding to the multiplication coefficient h and inputs it to the drive control circuit 41. And the display data whose size has changed is
It is adapted to be inputted to the liquid crystal element 21 via the scanning signal applying circuit 23 and the information signal applying circuit 22.

In the present embodiment, the image conversion control circuit 44 shows the relationship between the adjustment signal and the driving voltage as shown in FIG. 6 and the relationship between the adjustment signal and the multiplication coefficient as shown in FIG. A table is provided, and a contrast control signal is output to the image conversion circuit 43 based on this table.

That is, for example, when the value of the adjustment signal increases,
As is apparent from FIG. 6, the drive voltage increases and a difference in brightness occurs on the display surface 1C, but the image conversion control circuit 44 responds to the increase in the value of the adjustment signal by the multiplication coefficient h. Therefore, the difference in the brightness of the image before and after the adjustment of the drive signal can be kept to a minimum.

Next, the image display operation of the liquid crystal device thus constructed will be described.

When the operator operates the adjustment volume 45 to change the drive voltage, the image conversion control circuit 44 monitors the adjustment signal input from the adjustment volume 45 to the drive control circuit 41, and outputs the contrast control signal to the image conversion circuit. Four
Enter 3 Then, the image conversion circuit 43 receiving the contrast control signal automatically sets the contrast / enhancement function, and the graphic controller 42
Image conversion is performed according to the display data supplied from the display control circuit 41, the scanning signal applying circuit 23, and the information signal applying circuit 22 to display on the liquid crystal element 21. This allows
The difference in brightness on the display surface of the liquid crystal device can be compensated.

Although the case where the drive voltage V is changed according to the adjustment signal has been described in the present embodiment, the present invention is not limited to this, and the drive frequency f may be changed instead of the drive voltage. .

[0040]

As described above, according to the present invention, the compensation signal is supplied to the drive signal supply means in accordance with the change in the drive signal, so that the difference in the brightness of the display screen caused by the change in the drive signal is eliminated. Since compensation can be performed, the difference in brightness of the display image before and after the adjustment of the drive signal can be kept to a minimum.

[Brief description of drawings]

FIG. 1 is a block diagram of a display device according to the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal element.

FIG. 3 is a chart showing physical properties of liquid crystal.

FIG. 4 is a sectional view of a housing of the liquid crystal element.

FIG. 5 is a chart showing a relationship between a multiplication coefficient of a contrast / enhancement function and input / output data.

FIG. 6 is a chart showing a relationship between an adjustment signal and a driving voltage.

FIG. 7 is a chart showing a relationship between an adjustment signal and a multiplication coefficient.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal device 4a, 4b Glass substrate 12 Ferroelectric liquid crystal 21 Liquid crystal element 22 Information signal application circuit 23 Scan signal application circuit 41 Drive control circuit 43 Image conversion circuit 44 Image conversion control circuit 44a Change amount detection unit 45 Adjustment volume 5A Scan electrode Group 5B Information electrode group

Claims (10)

[Claims] 1. A liquid crystal device for displaying an image by driving a liquid crystal filled between substrates with a drive signal applied to a drive electrode, wherein a drive signal supply means for supplying a drive signal to the drive electrode, A liquid crystal device comprising: a drive signal changing unit for changing the drive signal; and a compensating unit for compensating for a difference in brightness of a display image caused by a change in the drive signal by the drive signal changing unit. . 2. The compensating means includes a change amount detecting section for detecting a change amount of the drive signal, and a compensating signal for compensating for a difference in brightness of the display image according to a detection signal from the change amount detecting section. Is output to the drive signal supply means. 3. The compensating means outputs the compensation signal based on a table showing a relationship between a variation amount of the drive signal and a compensation signal corresponding to the variation amount. Liquid crystal device. 4. The liquid crystal device according to claim 1, wherein the drive signal changing means is configured to change the drive signal by a manual operation. 5. The liquid crystal device according to claim 4, wherein the drive signal changing means is an adjusting knob. 6. The liquid crystal device according to claim 1, wherein the drive signal changing unit changes a drive voltage of the drive signal. 7. The liquid crystal device according to claim 1, wherein the drive signal changing means changes a frequency of the drive signal. 8. The liquid crystal device according to claim 1, wherein the drive electrode is a matrix electrode having a scan electrode group and an information electrode group. 9. The liquid crystal device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal. 10. The liquid crystal device according to claim 1, wherein the liquid crystal is a chiral smectic liquid crystal.