JPS59214015A - Liquid-crystal display device - Google Patents

Abstract

PURPOSE:To improve display quality by providing only two states, i.e. a lighting and a crosstalk state in a visual area. CONSTITUTION:The 1st scanning electrode group 8 and the 2nd scanning electrode group 10 are arranged on the surface of one transparent substrate of a liquid-crystal display panel 12, and the 1st signal electrode group 9 and the 2nd signal electrode group 11 are arranged on the surface of the other transparent plate. Further, the 1st picture element group wherein the electrode group 8 and electrode group 9 cross each other forms a display area for displaying characters, etc., and the 2nd picture element group wherein the electrode groups 8 and 11 cross each other and the 3rd and the 4th picture element groups wherein the electrode group 10 and electrode groups 9 and 11 cross each other are arranged at the circumference of the display area 2. Electrodes 8 and 10 are driven on time-division basis, and the electrode group 9 is supplied with a voltage signal corresponding to display information while the electrode group 8 is selected or with a nonselection or selection signal voltage while the electrode group 10 is selected. Then, the occupation ratio of the 1st picture element group in the display area is almost equal to those of the 2nd - the 4th picture element groups.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal display device that can be used for displaying information on personal computers, measuring instruments, and the like.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, liquid crystal display devices have been used as display devices for portable personal computers, measuring instruments, and the like, and their use in both fields and quantities has been increasing significantly year by year.

Recently, the display capacity has become larger and larger, such as display devices for word processors that display two lines of kanji, and display devices for personal computers that display eight lines of the alphabet. .

There are various types of liquid crystal displays, such as TN type, DSM type, and phase change type, among which TN type is the most commonly used. This TN type liquid crystal display device will be explained below.

Driving methods for TN type liquid crystal display devices can be roughly divided into two types: static driving and time division driving (multiplex driving or dynamic driving). The former is limited to relatively small-scale display devices such as those used in wristwatches, while all devices used in the personal computers mentioned above are time-division drive, and the latter will account for an increasing proportion of the total in the future. I think it will go.

Hereinafter, a liquid crystal display panel used in a conventional liquid crystal display device will be described with reference to the drawings.

FIG. 1 is a plan view of a liquid crystal display panel, and the region 1 surrounded by the two-dot chain line in the figure is the visible region, which is the region visible from outside the device when it is installed in a device such as a personal computer. Further, an area 2 surrounded by a broken line in the figure is a display area, and is a part where characters and the like are displayed. As shown, the visible area 1 includes a display area 2 and a portion outside the display area. Figure 2 is a partially enlarged view of the electrode layout of a liquid crystal display panel.
This figure shows the arrangement of two display areas and the transparent electrodes arranged around them. In the figure, 3a, 3h, 3c...3
h is a scanning electrode group, 4a, 4b, 4a...4j
is a signal electrode group, and the scanning electrode group 3 and the signal electrode group 4 are orthogonal to each other. This kind of liquid crystal display panel is usually called a dot matrix liquid crystal display panel.
The portion where the signal electrode group 4 and the scanning electrode group 3 intersect is a display pixel. There is a liquid crystal layer between the signal electrode group 4 and the scan electrode 3, and whether the light is turned on or off is determined depending on the effective value of the potential difference between the signal electrode and the scan electrode. As can be seen in the figure, one scanning electrode, for example 3a, is connected to a plurality of display pixels. Similarly, one signal electrode, for example 4a, is also connected to a plurality of display pixels.

In such a liquid crystal display panel, when time-division driving is performed, the display pixels have a selected state, that is, a lit state, and a non-selected state, but even in the non-selected six-page state, they are completely non-lit. It is well known that the light does not turn on but remains slightly lit, that is, it becomes a half-lit state, and this half-lit state is called crosstalk.

Crosstalk becomes more noticeable as the duty ratio of time-division driving becomes smaller (the higher the time-division driving becomes), and it actually becomes quite noticeable. In the future, as liquid crystal display panels become larger in size, it is inevitable that the duty ratio will become smaller, and there is little room for significant improvement in the characteristics of liquid crystal materials.
It cannot be expected to reduce crosstalk to a point where it can be ignored.

FIG. 3 is a plan view of a display pixel, showing only the display pixel of FIG. 2, and is an example indicated as [ABJ] in the figure. The colored display pixels in the figure are the pixels in the lit state,
The shaded display pixels are display pixels in which crosstalk occurs. Portions other than display pixels are completely non-lit.

FIG. 4 is a plan view of a conventional liquid crystal display panel in a character display state, and the hatched area indicates that crosstalk occurs in display pixels other than the lit state, as shown in page 6. In this way, there are three color states within the visible region: a lit part, a part where crosstalk occurs, and a background part that is not lit at all. In such a display, as is clear from FIG. 4, there are two types of contrast of the illuminated portion 6: the contrast with the portion 6 where crosstalk is occurring and the contrast with the background portion 7. , the former becomes blurred and the apparent contrast decreases as a result. It is also unfavorable from an aesthetic point of view and reduces display quality.

OBJECTS OF THE INVENTION An object of the present invention is to provide a liquid crystal display that eliminates the above-mentioned drawbacks and allows only two states, a lighting state and a crosstalk state, to exist in the visible region, thereby improving display quality. The purpose is to provide equipment.

Structure of the Invention The liquid crystal display device of the present invention has a liquid crystal display panel in which a liquid crystal is sandwiched between two parallel transparent substrates, and a first 7-page surface of one of the facing transparent substrates of the liquid crystal display panel is provided. A first signal electrode group and a second signal electrode group are arranged on the surface of another transparent substrate, and a first signal electrode group and a second signal electrode group are disposed on the surface of another transparent substrate, and A first pixel group that intersects with a signal electrode group forms a display area for displaying display information such as characters, and a second pixel group that intersects with a first scanning electrode group and a second signal electrode group forms a display area for displaying display information such as characters. 2 scanning electrode groups and the first
A third and a fourth pixel group are arranged at the periphery of the display area, and the first and second scanning electrode groups are driven by time division driving, and the first signal electrode group intersects with the second signal electrode group. A voltage signal according to display information is applied to the electrode group during a period when the first scanning electrode group is selected, and a non-selection voltage signal or a selection voltage signal is applied to the electrode group during a period when the second scanning electrode group is selected. ,
Either a non-selection voltage signal or a selection voltage signal is applied to the second signal electrode group, and the ratio of the area occupied by the first pixel group within the display area to the second. Third. By making the ratio of the area occupied by the fourth pixel group in the peripheral part of the display area almost the same, only two states, the lighting state and the crosstalk state, exist in the visible region.
15(3) In this way, display quality can be improved.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is a partially enlarged view of the electrode arrangement of a liquid crystal panel in a liquid crystal display device according to an embodiment of the present invention, showing the arrangement of transparent electrodes arranged in two display areas and their surrounding areas. In the figure, 8a, 8b, 8c, . . . , 8h are a first scanning electrode group, which correspond to the scanning electrode group 3 of the conventional example shown in FIG. Also, 9a, 9b.

9C...9j is the first signal electrode group and also the second signal electrode group.
This corresponds to signal electrode group 4 in the figure. This first scanning electrode group 8
and the first signal electrode group 9 constitute a first pixel group, which becomes a display area. Furthermore, 10a and 10b.

10C is the second scanning electrode group, 11a, 1lb
, 11c.

11d and 11e are second signal electrode groups, and a second pixel group consisting of a first scanning electrode group 8 and a second signal electrode group 11, as well as a second pixel group consisting of a second scanning electrode group 10 and a first signal electrode group. The third and fourth pixel groups, which are configured by the second signal electrode groups 9 and 11, are arranged around the display area.

FIG. 6 is a block diagram of a drive circuit for driving the liquid crystal panel of this embodiment. In the figure, reference numerals 8 , 9 , 10 , and 11 are the scanning and signal electrodes described above, which constitute the liquid crystal panel 12 . 13 is a signal electrode driver, 14 (
d shift register latch, 16 external system, 16
1 is a scanning electrode driver, 17 is a shift register, 18 is a timing controller, 19 is a signal electrode selection voltage line, 2
o is a signal electrode non-selection voltage line, 21 is a scan electrode selection voltage line, and 22 is a scan electrode non-selection voltage line. The timing controller 18 sends a timing signal to the shift register 17, so that the scan electrode driver 16 applies either a scan electrode selection voltage or a scan electrode non-selection voltage to the first and second scan electrode groups 8 and 1°. By sequentially controlling the timing, the liquid crystal panel 12 is driven in a time division manner. On the other hand, display data from the external system 16 corresponding to the display content of the selected scan electrode is transferred to the shift register.
The signal electrode driver 13 selects either the signal electrode selection voltage or the signal electrode non-selection voltage according to the display data and applies it to the first signal electrode group 9 via the page latch 14, and the liquid crystal panel 12 performs display. is controlled to be the signal electrode non-selection voltage regardless of the data during the period when the second scanning electrode group 10 is selected. A signal electrode non-selection voltage is always applied to the second signal electrode group 11. In this way, the pixel group is composed of the second scanning electrode group 1o and the first and second signal electrode groups 9 and 11, and the pixel group is composed of the first scanning electrode group 8 and the second signal electrode group 11. The pixel group is always in a non-selected state, that is, a state in which crosstalk occurs.

In addition, by driving in this way, the duty ratio becomes slightly smaller, so the display quality may be slightly degraded. /33,
Expressed as a margin that can represent the display quality depending on the duty ratio, 1/32 is 1.196, 1/33 is 1,192, and there is only 11-' sunset of 0.3 inches, and it has been confirmed experimentally. However, the difference is easily recognized and can be ignored.

FIG. 7 is a plan view of the pixel group in this embodiment, and shows only the pixel group in FIG. 6. This is an example in which "ABJ" is displayed by the drive circuit in FIG. It can be seen that groups are arranged.In the figure, the colored portions are lit pixels, and the diagonally shaded pixels are pixels that are causing crosstalk.

FIG. 8 is a plan view of a liquid crystal display panel in a character display state according to an embodiment of the present invention. There are only two parts in the visible area: the illuminated part and the part where crosstalk occurs, and as you can see from Figure 4, the display is easy to see, making it easy to see the characters. It can be seen that the contrast at the top has improved.

When looking at the entire visible region macroscopically as shown in FIG. 8, it is desirable that the degree of coloring within the display region and its surroundings be the same. To this end, it is sufficient to make the ratio of the area occupied by each pixel, that is, the aperture ratio, approximately equal between the inside of the display area and the peripheral area.

In addition, the above description has been made for positive display, that is, display of black characters on a white background, but for negative display, that is, display of white characters on a black background, it is better to switch the signal electrode selection voltage and the signal electrode non-selection voltage. A liquid crystal display device can be provided, and its industrial value is great.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a liquid crystal display panel of a general liquid crystal display device, Fig. 2 is a partially enlarged view of the electrode arrangement of a conventional liquid crystal display panel, Fig. 3 is a plan view of a conventional display pixel, and Fig. 4 5 is a plan view of a conventional liquid crystal display panel in a character display state, FIG. 5 is a partially enlarged view of the electrode arrangement of the liquid crystal display panel of a liquid crystal display device according to an embodiment of the present invention, and FIG. 6 is a diagram showing the driving of the same liquid crystal display panel. A block diagram of the circuit, Figure 7 is a plan view of the same pixel group, Figure 8 is a block diagram of the circuit.
The figure is a plan view of the liquid crystal display panel in the same character display state. 13Baget...Visible area, 2...Display area, 3.
・River/scanning electrode group, 3a, 3b, 3c, aa,
3e, 3f. 3g, 3h...Scanning electrode, 4.Old...Signal electrode group, 4a, 4b, 4c, 4d, 4e, 4f
, 4g, 4h. 4i, 4j... Signal electrode, 6... Mark/lighting part, 6... Part where crosstalk occurs, 7...
...Background part, 8...First scanning electrode group, 8a, 8b, 8c. 8d, 8e, 8f, Bq, Bh-■-first scanning electrode, 9...first signal electrode group, 9a, 9b, 9a
. 9d, 9e, 9f, 9q, sh, 9i, 9
j・mountain・-first signal electrode, 10...second scanning electrode group, 10a, 1ob, 10a・---
--Second scanning electrode, 11... Second signal electrode group, 11a, 11b, 11c. 11d, 11e... second signal electrode, 12...
Mark/Liquid crystal panel, 13...Signal electrode driver,
14・Old...Shift register/latch, 16...River/External system, 16...Scan electrode driver, 17
...Shift register, 18...Timing controller, 19...Signal electrode selection voltage line, 20...Signal electrode non-selection voltage line, 21...
. . . Scanning electrode selection voltage line, 22 . . . Page 14 Scan electrode non-selection voltage line. Name of agent: Patent attorney Toshi Nakao Haga 1 person 41
E t 2 Figure 2 Figure 3 Figure 4 Figure 5 Figure 1 Figure 6 11 γ ll De ll

Claims (1)

[Claims] (1) It has a liquid crystal display panel in which a liquid crystal layer is sandwiched between two parallel transparent substrates, and a first scanning electrode is provided on one surface of the transparent substrate facing each other with the liquid crystal layer of the liquid crystal display panel sandwiched therebetween. A first signal electrode group and a second signal electrode group are arranged on the surface of the other transparent substrate, and the first signal electrode group and the second signal electrode group are disposed on the surface of the other transparent substrate.
forming a display area for displaying display information such as characters in a first pixel group where the scanning electrode group and the first signal electrode group intersect;
A second pixel group where the first scanning electrode group and the second signal electrode group intersect; and a third and fourth pixel group where the second scanning electrode group and the first and second signal electrode groups intersect. are arranged around the display area, the first and second scanning electrode groups are driven by time division driving, and the first signal electrode group receives display information during the period when the first scanning electrode group is selected. During the period when the second scanning electrode group is selected, a non-selection signal voltage or a selection signal voltage is applied to the second page, and a non-selection voltage signal or a selection voltage is applied to the second signal electrode group. A liquid crystal display device configured to provide either signal. (→ Claim 1D in which the ratio of the area occupied by the first pixel group in the display area and the ratio of the area occupied by the second, third, and fourth pixel groups in the peripheral part of the display area are approximately the same) The liquid crystal display device described.