JP2985734B2 - Color liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device of the active matrix type, and more particularly to a color liquid crystal display device in which the display pixels are arranged in a so-called delta arrangement and the scanning in the row direction is improved.

[0002]

2. Description of the Related Art In general, a liquid crystal display device has attracted attention as a display device replacing a CRT because of very low power consumption and the like, and has been widely used. In a color filter used in a color liquid crystal display device, a primary color filter portion generally has a delta shape, and accordingly, display pixels are also arranged in a delta arrangement. Examples of active matrix type color liquid crystal display devices in which display pixels are arranged in a delta arrangement are disclosed in, for example, US Pat. No. 5,144,288, JP-A-63-168689, and JP-A-63-8559.
No. 9, JP-A-63-91692 and the like are known.

FIG. 7 shows an example of a conventional color liquid crystal display device in a delta arrangement, in which a pair of R, G, and B pixels adjacent to each other over two rows are all arranged in a triangle (delta) shape. I have. In this figure, DR _i , DB _i , DG _i ,.
DG _{i + 2} ... Indicate column signal electrodes, L _j , L _{j + 1} ... Indicate row scanning electrodes, and a portion surrounded by a square indicates a liquid crystal display pixel 1 corresponding to each of RGB colors. Here, RGB indicates the three primary colors of light, R indicates red, G indicates green, and B indicates blue. Column signal electrodes DR _i , DB _i , DG
_The display signals corresponding to the arrangement of the display pixels of each color are supplied to _i ... DG _{i + 2} . On the other hand, switching pulses, which are switched in a cycle of one scanning line period of the display signal, are sequentially supplied to the row scan electrodes L _j , L _{j + 1} ,... From the row scan electrode drive circuit 3 to the display pixels of the selected row. The display signal is written. Two rows of the pixel array in this embodiment, for example, figure PL _n and PL n _{+ 1} is selected in the same row scanning electrodes, for example L _j, it becomes active.

FIG. 8 is a view showing an example of another color liquid crystal display device of a delta arrangement according to the prior art. In this device example, for example, a double-speed conversion method is employed in which a display signal for one scanning line of a display signal is sequentially written in a time-division manner over two rows of a pixel array. In this example, the information of one scanning line of the display signal is converted into a double speed signal by a scanning speed converting means (not shown) including an external memory means, and the column signal electrode lines DR, D
G, DB,... And row scan electrodes L _j , L
_{j + 1} ,..., two consecutive lines, for example, L _j and L _{j + 1} are 1
Time-division driving is performed so as to be sequentially activated in the first half and the second half during the scanning period. At this time, the display signal whose sampling point is shifted according to the position of each color pixel for each row is output to the column signal electrode DR,
DG, DB,... To improve the resolution in the horizontal direction.

FIG. 9 is a diagram showing a relationship between a pixel arrangement and a display signal of the above two devices. In the figure, for example, a portion indicated by oblique lines corresponds to a display signal for one scanning line (one line), and two rows of pixel columns are in an active state.

[0006]

As described above, in the conventional apparatus, the information for one scanning line of the display signal is displayed in two rows of the pixel array in any case, so that the effective scanning line of the image to be displayed is provided. Requires twice as many rows of pixels. Therefore,
In a conventional delta array type color liquid crystal display device, one line (scanning line) of an image signal is displayed by a pixel array of two rows, and therefore, a column direction (vertical direction in the figure).
However, there is a problem that the resolution of the displayed image is degraded as a result.

In particular, in a projection type liquid crystal display device,
Due to demands for miniaturization of devices and cost reduction of optical systems, display panels are required to be miniaturized.
It is also desired to deal with high-resolution images such as those described above, but the above-mentioned problems will be noticeable. For example, assuming that the effective pixel area of the display panel is 2 inches, the aspect ratio (the aspect ratio of the screen)
Consider the case of displaying 16: 9 HDTV video. When the number of samplings for each color in the horizontal direction is set to 1300 to 1500 for 1035 effective scanning lines, the pixel arrangement in the conventional method is as shown in Table 1. Note that, as is clear from FIG. 7, sampling in the horizontal direction of each color is performed at every 1.5 pixel pitch.

[0008]

[Table 1]

Thus, in the configuration of the conventional device, the column (vertical)
The pixel arrangement pitch in the direction becomes about 50 to 60% of the pitch PH in the row (horizontal) direction, and the arrangement itself becomes horizontally long. When the aspect ratio of the pixel arrangement pitch is largely deviated from 1: 1 as described above, the degree of the influence of the resolution degradation and the substantial aperture ratio reduction due to the electric field distribution in the liquid crystal is more remarkable especially in the short pitch direction. There is a problem that it is easy to do. FIG. 10 shows a configuration example of a projection type color display device.
1 shows a configuration using fine lenses as color separation means. In brief, the light source LS in FIG.
Light from the three dichroic mirrors DM _R and DM
_G, is decomposed into three primary colors of each different incident angles by DM _B, it passes through the microlens plate MLP, given the active matrix panel unit AMP. This panel part A
Light emitted from MP is collected by the projection lens PL.

As shown in FIG. 11, one fine lens M
Focusing on L, light of each color incident on the lens ML at a different angle forms a spot on a pixel of the corresponding color, and receives a modulation corresponding to each color at each pixel to display a color image. This device example has a feature that higher light use efficiency can be achieved as compared with a configuration in which a color filter is provided for each pixel. Here, FIG. 12 illustrates the positional relationship between the pixel arrangement of each color and the arrangement of the fine lenses in the present embodiment on the same image. As described above, in the conventional display device of the delta arrangement, the aspect ratio of the pixel arrangement pitch becomes horizontally long especially when HDTV is supported, and as a result, the fine lens ML in FIG.
Is correspondingly horizontally long. When such a horizontally long lens is realized by a normal fine lens forming process, there is a problem that aberration increases and performance is deteriorated.

Further, especially in the case of the apparatus example shown in FIG.
Circuits such as a scanning speed conversion unit must be separately provided, which causes an increase in cost. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in order to effectively solve the problems. The purpose of the present invention is to provide information for one scanning line of a display signal for 1.5 rows of a row pixel array. It is another object of the present invention to provide a color liquid crystal display device capable of displaying a color image.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a liquid crystal display device comprising a switching element and a liquid crystal display element as display pixels of three different colors in a predetermined repetition order in a row direction. And a liquid crystal display pixel group in which display pixels of the same color in adjacent rows are arranged so as to be shifted from each other by 1.5 pixels in the column direction, and a switching element of each liquid crystal display pixel corresponds to each color. A plurality of column signal electrodes for supplying a selected display signal, a plurality of row scanning electrodes for supplying a scanning signal to a switching element of each of the liquid crystal display pixels to selectively turn on / off, and the column signal electrode. In a color liquid crystal display device including a column signal electrode drive circuit for driving the pixel electrodes and a row scan electrode drive circuit for driving the scan electrodes, one of three consecutive rows in the row direction array of the display pixels is provided. For an array of pixels, the switching elements of the display pixels that are adjacent on the same row, which is constituted to be connected alternately to different two rows scan electrodes.

[0013]

Since the present invention is constructed as described above, the pitch of display pixels which are selected by the same row scanning electrode and become active is 1.5 pixel pitch in the column direction on average. That is, one scanning line (1) of the display signal is used without using a special scanning speed converting means such as an external memory.
It is possible to display information of (line) for 1.5 rows of the row pixel array. Therefore, even when an HDTV-compatible device is configured, the aspect ratio of the pixel array pitch can be set close to 1: 1. Therefore, the direction dependency of the resolution and the aperture ratio can be eliminated. Further, even when a fine lens array is used, the lens shape does not become flat, and good optical system performance can be secured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color liquid crystal display device according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram showing a first embodiment of a color liquid crystal display device of the present invention, FIG. 2 is a circuit configuration diagram of one display pixel in the device shown in FIG.
FIG. 3 is a diagram showing the correspondence between the pixel arrangement of the device shown in FIG. 1 and the display signals for one scanning line. The same parts as those of the conventional device shown in FIG.

In the illustrated example, the rectangular liquid crystal display pixels 1 are arranged in the row direction (horizontal direction in the drawing) in a predetermined repetition order as display pixels of three colors different in RGB, and are arranged in columns (FIG. In the (middle vertical direction) direction, the same-color display pixels in adjacent rows are arranged so as to be shifted from each other by 1.5 pixels, and a so-called delta arrangement in which the same-color display pixels are arranged in a triangular shape. DR _i , DB _i , DG _i ,
.. DG _{i + 2} ... Indicate column signal electrodes, and L _j , L _{j + 1} . The row scanning electrodes L _j , L _{j + 1} ,... Are not arranged at all between the element arrays PL _n , PL _{n + 1} , PL _{n + 2} ,. It is provided intermittently so that it is not provided between the next element arrays. Each column signal electrodes _{DR i, DB i, DG i} ... DG
_{i + 2} ... it is connected to the column signal electrode driving circuit 2, which each display signal corresponding to the arrangement of the display pixel of the color is supplied from.

On the other hand, each row scanning electrode L _j , L _{j + 1,.}
A switching pulse (selection signal) which is connected to the row scan electrode drive circuit 3 and is switched in a cycle of one scan line period of the display signal is sequentially supplied from the row scan electrode drive circuit 3, and the display signal is supplied to the display pixels of the selected row. Is written. Then, as for the pixels arranged in one row (center row in the illustrated example) of the three consecutive rows in the row direction array of the display pixels, the switching elements of the adjacent display pixels on the same row (see FIG. 2) .. Are connected alternately to two different row scanning electrodes, for example, _Lj and _{Lj + 1} , _{Lj + 2} and _{Lj + 3} .

More specifically, three consecutive rows of pixel arrays PL
_n, PL _n + _1, PL Focusing on n + _2, the PL _n row switching elements of all the display pixels (FIG. 2
The middle switching transistor Tr) is connected to the same row scanning electrode _Lj , and in the PL _{n + 2} row, the switching elements of all display pixels are connected to the row scanning electrode L _{j + 1} .
For the PL _{n + 1} row located between these two rows, the switching elements of adjacent pixels are alternately connected to different row scan electrodes L _j and L _{j + 1} . Here, as shown in FIG. 2, one display pixel 1 includes a switching transistor Tr as a switching element, a storage capacitor CS, and a liquid crystal display element LC. Then, the row scanning electrode L is connected to the gate of the switching transistor Tr. In the figure, reference numeral 4 denotes a transparent common electrode connected to the storage capacitor CS and the display pixel 1.

Next, the operation of the embodiment constructed as described above will be described. Now, the selection signal from the row scanning electrode drive circuit 3 to the row scanning electrodes L _j is supplied, all of the switching transistor Tr connected to the electrode L _j becomes conductive, from the column signal electrode driving circuit 2 in this state The display signal supplied to each column signal electrode DR _i , DB _i , DG _i ... Is written to the display pixel 1 via the switching transistor Tr. As a result, the information of one line of the display signal is written into the display pixels indicated by oblique lines in FIG.
During the next one scanning line period, the row scanning electrode _{Lj + 1} becomes active, and this time, writing is performed on the display pixel 1 in the non-hatched portion (white) in FIG. Hereinafter, writing is performed on all display pixels in the same manner.

From the above configuration and operation, a display signal for one scanning line (one line) is displayed by 1.5 rows of the pixel array. Therefore, the total number of rows of the pixel array may be 1.5 times the number of effective scanning lines of the image to be displayed. That is, in the conventional device shown in FIG. 7 and the like, the display signal for one scanning line is displayed by two rows of the pixel array. It will take only lines.

Further, regarding the sampling number for each color in the row (horizontal) direction, when attention is paid to a pixel of a specific color (for example, R in the figure) in the display information of one scanning line shown in FIG. Since there are three samplings per pixel, it can be considered that one sampling is taken every two pixels on average. Here, corresponding to Table 1 shown in the conventional device example, Table 2 shows a pixel arrangement when a 2-inch diagonal HDTV-compatible element is configured according to the present invention.

[0021]

[Table 2]

Here, the number of samplings for each color in the horizontal direction is set to 1300 to 1 for 1035 effective scanning lines.
The case where it is set to 500 is shown. As is apparent from comparison with Table 1 above, in the configuration like the present invention, the ratio of the pixel array pitch (PH: PV) is a value close to approximately 1: 1 and a good result is shown. Therefore, since the aspect ratio of the pixel arrangement pitch can be made approximately 1: 1, it is possible to suppress the deterioration of the resolution and the decrease of the aperture ratio based on the electric field distribution in the liquid crystal.

In the apparatus example shown in FIG. 1, two row pixel electrodes are commonly connected to one row scanning electrode provided between two row pixel arrays. The present invention is not limited to this. For example, as shown in FIG. 4, row scanning electrodes are provided between all row pixel arrays, each electrode is connected to an individual row pixel array, and a pair of adjacent row scanning electrodes They may be connected at an appropriate place. According to this, the same operation and effect as the apparatus of FIG. 1 can be exerted.

Next, a second embodiment of the present invention will be described. In this embodiment, a configuration example of a color liquid crystal display device suitable for displaying a video signal of 2: 1 interlaced scanning (interlaced scanning) is shown. Normally, in a liquid crystal display element, it is necessary to drive the liquid crystal by AC, and the polarity of the display signal is inverted at a field cycle or a frame cycle. On the other hand, NTSC (National Telsvisio)
In the current television system such as n System Committee or HDTV, the video signal is an interlaced signal with a frame frequency of 30 Hz, and when writing to the liquid crystal display element is performed in an interlaced manner corresponding to this, each pixel becomes 1 pixel. Since it is selected only once per frame, the frequency of the AC drive is 15 Hz, which is １ ／ of the frame frequency. Therefore, there is a problem that flicker of the display pixels easily occurs. In this embodiment, this flicker phenomenon can be solved.

FIG. 5 is a block diagram showing a second embodiment of the present invention. The same parts as those of the apparatus shown in FIG. 5, the connection between each display pixel 1 and row scanning electrodes L _j , L _{j + 1} , L _{j + 2} ... And column signal electrodes DR, DB, DG... Is the same as in the first embodiment of FIG. However, in FIG. 5, the switching means SW _k , SW _{k + 1} , SW between the row scan electrode drive circuit 3 and each row scan electrode
_{k + 2} ... are provided. A pair of control signals S1 and S2 are provided to control the switching of these switch means, and control signals of opposite polarities are supplied to the control signal lines S1 and S2. The changeover switch means is alternately connected to the different control signal lines S1 and S2.
Every other changeover switch means is controlled by the same control signal.

During the odd field period of the video signal, every other changeover switch means SW _k , SW _{k + 2} ... Become conductive, and every other changeover switch means SW _{k + 1} ,.
SW _{k + 3} ... Are turned off. as a result,
(L _j , L _{j + 1} ) and (L _j ) of two adjacent row scan electrodes
_{j + 2} , L _{j + 3} )... are selected and selected simultaneously in each combination. Accordingly, in the odd-numbered field, a display signal for one scanning line is written with the pixel array indicated by oblique lines in FIG. 6A as one unit.

Next, during the even field period of the video signal, the changeover switch means SW _{k + 1} , SW _{k
k + 3} ... is turned on, the other of the switch means SW
_k, the switch is switched to SW k + ₂ ... becomes nonconductive. As a result, the combination of the row scanning electrodes is shifted one by one instead of the above, and (L _j )
(L _{j + 1} , L _{j + 2} ), (L _{j + 3} , L _{j + 4} )... _Are combined, and the combination of the row scanning electrodes is shifted by one row with respect to the odd field. Become. At this time, 1
The display signals for the scanning lines are written using the pixel array in the hatched portion in FIG. 6B as one unit.

According to the second embodiment, since all the pixels are selected in one field period even for the interlaced video signal, the AC driving frequency of the liquid crystal display element is set to the field frequency (30 Hz). )
Image display with less flicker is possible. Also, odd numbers,
By changing the combination of the row scan electrodes between even fields, a high vertical resolution can be obtained. The structure described in each of the above embodiments can also be applied to a projection type color liquid crystal display device, for example, in combination with the fine lens plate MLP as the fine lens array means described in FIG. 10 as an applied device. .

The present invention is characterized by the configuration of the row scanning electrodes of the color liquid crystal display device of the delta arrangement. The active matrix type substrate has a structure in which a switching element is formed by a thin film transistor on a semiconductor substrate or an insulating substrate. Is used, and M is formed on a semiconductor substrate.
A device in which a switching element is formed using an OS transistor can also be used. Further, the present invention can be applied to both a transmission type and a reflection type display device.

[0030]

As described above, according to the color liquid crystal display of the present invention, the following excellent functions and effects can be exhibited. The information for one scanning line (one line) of the display signal can be displayed in 1.5 rows of the row pixel array without using a special scanning speed conversion means such as an external memory. Therefore, even when an apparatus compatible with HDTV is configured, the aspect ratio of the pitch of the pixel array can be set to be close to 1: 1 and the direction dependency of the resolution and the aperture ratio can be eliminated. Further, even when the fine lens array means is used, the lens shape does not become flat, and good optical system performance can be secured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a color liquid crystal display device according to the present invention.

FIG. 2 is a circuit configuration diagram of one display pixel in the device shown in FIG.

FIG. 3 is a diagram showing a correspondence between a pixel array of the device shown in FIG. 1 and a display signal for one scanning line.

FIG. 4 is a view showing a modification of the first embodiment of the device of the present invention.

FIG. 5 is a configuration diagram showing a second embodiment of the device of the present invention.

FIG. 6 is a diagram showing the correspondence between the pixel array of the second embodiment and display signals for one scanning line.

FIG. 7 is a configuration diagram showing a conventional color liquid crystal display device.

FIG. 8 is a configuration diagram showing another conventional color liquid crystal display device.

FIG. 9 is a diagram showing a correspondence between a pixel array and a display signal for one scanning line in a conventional device.

FIG. 10 is a schematic explanatory view of a projection type color liquid crystal display device.

11 is an explanatory diagram of the principle of color separation by a fine lens of the device shown in FIG.

12 is a diagram showing a positional relationship between a pixel array and a fine lens of the device shown in FIG.

[Description of Signs] 1 ... liquid crystal display pixel, 2 ... column signal electrode drive circuit, 3 ... row scan electrode drive circuit, 4 ... common electrode, D, DR, DB, DG
... different signal electrodes, DM: dichroic mirror, L: row scanning electrode, LC: liquid crystal display element, MLP: fine lens plate (fine lens array means), S1, S2: control signal lines, SW: changeover switch, Tr: switching Transistor (switching element).

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-2525 (JP, A) JP-A-64-31128 (JP, A) JP-A-63-179388 (JP, A) JP-A-63-179388 91628 (JP, A) JP-A-61-190315 (JP, A) JP-A-60-218626 (JP, A) JP-A-59-9636 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G02F 1/1343 G02F 1/1335 505 G02F 1/136 500

Claims (6)

(57) [Claims] 1. A plurality of liquid crystal display pixels comprising a switching element and a liquid crystal display element are arranged as display pixels of three different colors in a row direction in a predetermined repetition order, and display pixels of the same color in adjacent rows are arranged in a column direction. A liquid crystal display pixel group arranged so as to be shifted from each other by 1.5 pixels, a plurality of column signal electrodes for supplying a display signal corresponding to each color to a switching element of each liquid crystal display pixel, A plurality of row scan electrodes for supplying a scan signal to a switching element of a liquid crystal display pixel to selectively turn on / off, a column signal electrode drive circuit for driving the column signal electrode, and a row for driving the scan electrode A color liquid crystal display device having a scan electrode driving circuit, wherein three consecutive display pixels in a row direction are arranged.
A color liquid crystal display, wherein the switching elements of adjacent display pixels on the same row are alternately connected to two different row scanning electrodes for one row of the array pixels. Display device. 2. The color liquid crystal display according to claim 1, wherein the array pixels in which the switching elements are alternately connected to different row scanning electrodes are the middle array pixels of the three rows of array pixels. apparatus. 3. A plurality of changeover switches for electrically connecting the adjacent row scan electrodes to each other, and turning on and off every other changeover switch in the same state,
3. The color liquid crystal display device according to claim 1, further comprising a control signal line for switching the on / off state every time the field changes. 4. A color liquid crystal display device according to claim 1, further comprising a fine lens array means for irradiating light of a color corresponding to each of said display pixels. 5. The color liquid crystal display device according to claim 1, wherein a switching element of said liquid crystal display element is formed by a thin film transistor. 6. The color liquid crystal display device according to claim 1, wherein the switching element of the liquid crystal display pixel is a MOS transistor formed on a semiconductor substrate.