JP2997948B2 - Driving method of multicolor liquid crystal display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving method of a multi-color display device using a liquid crystal.

[Prior Art] Conventionally, in a multi-color display device using a liquid crystal, as shown in FIG. 4, a common electrode is provided for a plurality of horizontal pixel lines for each pixel of one line, and is orthogonal to the common electrode. In the direction, three segment electrodes Sr, Sg, Sb provided with three primary color filter layers of R (red), G (green), and B (blue) are provided for each pixel of each line, and a common electrode is provided. Selective scanning is sequentially performed by division (dynamic drive), and the selected common electrode is required to be able to output the color according to the color to be displayed in each pixel, from among the segment electrodes Sr, Sg, and Sb. An appropriate electrode is selected, and electricity is supplied to that electrode.

[Problem to be Solved] However, even in alphanumeric (alphabetic and numeric) display using a normal 5 × 7 matrix, the number of common electrodes is required seven, and an operating margin (α = on pixel (Effective voltage value applied / effective voltage value applied to OFF pixel) is low (α =
About 1.48), therefore, there was a problem that a high contrast could not be obtained and a vivid color could not be obtained.

In addition, there are an active matrix cell method in which a thin film transistor is provided for each pixel, such as a liquid crystal television, and a super twist mode (STN) method. The former has a good contrast but uses a semiconductor process, so the process is complicated. In addition, it is too expensive, and it is difficult to manufacture a large display device.The latter requires high precision in cell thickness control, making it difficult to make a uniform and large display device, and requires an optical phase plate in addition to a polarizing plate. And it is expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of driving a multicolor liquid crystal display device which is inexpensive, has high contrast and can produce a vivid color, and is capable of forming a large multicolor display device.

[Means for Solving the Problems] In order to achieve the above object, a method for driving a multicolor liquid crystal display device according to the present invention includes a segment electrode, a liquid crystal layer, a plurality of common electrodes, and a plurality of common electrodes corresponding to each of the common electrodes. In a multicolor liquid crystal display device having a plurality of pixels constituted by color filters of different colors and having common electrodes corresponding to color filters of the same color connected in common, the segment electrodes have the same waveform. One of two types of signals having different phases, segment on and segment off, is selectively supplied, and each of the common electrodes is
In accordance with a desired display color, any of the signals having the same waveform as the segment-on signal or the same waveform as the segment-on signal and different phases but excluding the segment-off signal is selectively supplied.

[Operation] The signal applied to each common electrode is the same as the segment-on signal or the same as the segment-on signal and the same waveform but different from the phase, except for the segment-off signal, according to the desired display color. Either of the signals is selectively provided.

When the same signal as the signal supplied to the segment electrode is supplied to a certain common electrode, when the signal is supplied to the segment electrode, the voltage applied to the liquid crystal becomes 0, so that the operation margin is infinite. can do.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

 First, a first embodiment will be described.

In FIG. 1, M × N pixels 1 are arranged in a matrix, and R (red), G (green), and B (blue) color filters are arranged for each horizontal pixel line. Kinds of common electrodes COMR, COMG, COMB are provided in parallel in this order. The position of the color filter may be on the liquid crystal side or on the surface side with respect to each of the common electrode positions. The common electrodes are connected in common for the same color, and the same signal is simultaneously supplied to the common electrodes of the same color. The common connection of the same type of common electrode may be performed in all panels, or may be performed for each pixel in a block of one display character. It should be noted that an intersecting portion of the wiring is provided with an insulating layer (not shown) interposed therebetween so as not to short-circuit each other.

Next, at each pixel position, a separate segment electrode 2 is provided for each pixel so as to face the common electrode and sandwich a liquid crystal layer (not shown). Each segment electrode 2 is supplied with a signal separately.

Note that an alignment film (not shown) is formed on the inner surface of each of the common electrode and the segment electrode, and is oriented in a predetermined direction. Even if a protective layer is provided between the color filter and the electrode. Further, a polarizing plate (not shown) is provided outside the common electrode and the segment electrode, and a white light source (not shown) is provided outside the polarizing plate.

 Next, a driving method will be described.

According to the present invention, n kinds of signals having the same waveform and different phases are prepared, and two kinds of signals are selected as segment on and segment off signals for the segment electrodes, and segment off for each of the n common electrodes. Select and supply any of the other signals except the signal, and supply a segment-on signal to the segment electrode to selectively respond or respond to the liquid crystal between each of the n common electrodes and the segment electrode. Non-response, a predetermined color is output by the combination, a segment-off signal is supplied to the segment electrodes, and the liquid crystal between all the n common electrodes and the segment electrodes is made to respond, and a segment-on signal is supplied. The color display is performed based on the difference between the color of the pixel and the pixel to which the segment-off signal is supplied. The operation margin can be made infinite by using the method of the present invention.

In FIG. 2, one cycle of the signal is divided into three, and a rectangular waveform having the same shape is provided at the first, second, and third positions from the front of the three divisions, ie, three types of signals having different phases, that is, the signal (1) ,
(0,0), (0,1,0), (0,0,1) are prepared, the signal (1,0,0) is used as the segment-on signal, and the signal (0,0) is used as the segment-off signal. , 1,0).

Next, any one of the signals (1, 0, 0) and (0, 0, 1) is selected and supplied to each of the common electrodes except for the segment off signal. With this combination, eight ways of giving signals can be obtained.

When the segment off signal (0,1,0) is supplied to the segment electrodes, the signals (1,0,0), (0,0,1)
No matter which of the above is selected, the effective voltage value of the signal applied to the liquid crystal is always the value to which the liquid crystal responds. Therefore, the pixel is normally white (a mode in which light is transmitted when no voltage is applied). In the case of a twisted nematic liquid crystal, when the polarizers are at right angles to each other), light cannot pass through the polarizers at all of the common electrodes, and is recognized as black by human eyes.

For example, in the second stage, signals (1,0,0), (0,0,1), (0,0,1) are supplied to the common electrodes COMR, COMG, and COMB, respectively, and a segment-off signal is supplied. All the liquid crystals respond and black is displayed. Next, at the second stage, when a segment-on signal is supplied, the common electrode COMR
Is 0, a signal having a voltage effective value to which the liquid crystal responds is applied between the common electrode COMG and the common electrode COMG.
A signal having a voltage effective value to which the liquid crystal responds is also applied between the common electrode COMB. Therefore, in normally white, only red light can be transmitted, and the pixel is recognized as red by human eyes. Thus, by combining the signals given to the common electrodes, eight colors can be displayed when the segment is on.

Considering the operation margin α, since the effective voltage value when the liquid crystal does not respond is 0, α = infinity, and
It is possible to obtain the maximum contrast of the display device, and therefore, it is not necessary to perform various adjustments according to the temperature change.

In this embodiment, two kinds of signals to be supplied to each common electrode are supplied in eight combinations in accordance with a color to be displayed, and a segment-on signal is supplied to a segment electrode of a pixel such as a character to be displayed. Then, a segment-off signal is supplied to the segment electrode of the background pixel. As a result, characters of a predetermined color and the like can be made to emerge on a black background.
When changing the color to be displayed, the same operation is performed by changing the combination of signals supplied to each common electrode. Further, for example, when it is desired to change the color to be displayed for each character, the wiring of the common electrode is divided into blocks for each part constituting one character on the display surface, and a different common electrode signal is supplied for each block. .

Note that when the display mode was normally black (a mode in which light was not transmitted when no voltage was applied and the polarizing plates were parallel to each other in the case of a twisted nematic liquid crystal), a segment-off signal was supplied. Since the liquid crystal of a part responds and transmits light, the light of each subsequent column of the display color column of FIG. 2 appears on a white background.

 Next, a second embodiment will be described.

In the present embodiment, the arrangement of the common electrodes is changed to eliminate the intersection of the wiring when connecting the same type of common electrodes.

In FIG. 3, the common electrode COMG is divided into two, that is, the common electrode COMG having a half width of the common electrode COMR or COMB.
Are formed, and the common electrode COMR, the common electrode COMG, the common electrode COMB, and the common electrode COMG are arranged in order for each pixel line. The common electrode COMR is connected to each other on the left end of the common electrode, the common electrode COMB is connected to each other on the right end of the common electrode, and the common electrode COMG is connected to the left end.
The wiring is connected alternately in the order of the right end, and the common electrode COMR
And the common electrode COMB. The signal supply method may be the same as in the first embodiment. Therefore, there is no need to provide an insulating layer or the like to prevent a short circuit, and wiring work can be simplified and cost can be reduced.

Note that the electrode divided into two may be the common electrode COMR or COMB, and the arrangement order may be any other order.

In the first and second embodiments, the signal supplied to the segment electrode and the common electrode is a signal having a rectangular waveform and a different phase. However, the waveform may have various shapes other than the rectangular shape and the phases of the waveforms may be different. You may do so.

Although the red, green, and blue color filters are used in the first and second embodiments, color filters of other colors may be used. In the first embodiment, the common electrode is not limited to three colors. Two or four or more colors may be used.

[Effects] With the above configuration, the present invention can provide an infinite operation margin at low cost, obtain the maximum contrast of the display device, produce vivid colors, and can be used in a wide temperature range. The viewing angle can be widened. Also, a large-sized multi-color display device can be used, and scroll display with the same color or the same color for each character block is also possible. Further, since the driving waveform can be composed of only one value, the circuit configuration becomes easy.

[Brief description of the drawings]

1 and 2 show a first embodiment of the present invention. FIG. 1 is an explanatory view of an electrode arrangement and a wiring pattern, and FIG. 2 is an explanatory view showing signals supplied to electrodes and waveforms obtained thereby. FIG. 3 is an explanatory view of an electrode arrangement and a wiring pattern according to a second embodiment of the present invention, and FIG. 4 is an explanatory view showing an electrode arrangement of a conventional example. 1 ... Pixel 2 ... Segment electrode COMR, COMG, COMB ... Common electrode

Claims (1)

(57) [Claims] A plurality of pixels each including a segment electrode, a liquid crystal layer, a plurality of common electrodes, and color filters of different colors corresponding to the respective common electrodes; In a multi-color liquid crystal display device in which a common electrode is connected in common, the segment electrode selectively receives one of two types of signal, segment on and segment off, which have the same waveform and different phases. Each of the common electrodes is supplied with one of the same signal as the segment-on signal or the same signal as the segment-on signal and having the same waveform but a different phase, excluding the segment-off signal, according to a desired display color. A method for driving a multi-color liquid crystal display device, wherein the method is selectively supplied.