JP2020101654A - Display device - Google Patents

Abstract

To provide an area gradation display device which suppresses the influence on the image quality due to pixel division and reduces a burden on a manufacturing process.SOLUTION: A display device includes a plurality of unit pixels PX arranged so as to be adjacent to each other. The unit pixel includes three subpixels PG, PB, PR that are arranged adjacently to display different colors. The three subpixels include N display areas respectively. The area gradation of N bits is possible with the combination of the display areas. The lowest bit display area of the display area corresponding to the lowest bit is rectangle. The display device is arranged so that the lowest bit display area of the subpixel displaying one color in one unit pixel touches the lowest bit display area of the subpixel displaying other two colors included in any of the same unit pixel and adjacent unit pixel, and the lowest bit display area of the subpixel of the unit pixel does not touch the upper bit display area corresponding to the upper bits of the subpixel in the same color of the adjacent unit pixel.SELECTED DRAWING: Figure 5

Description

Embodiments of the present invention relate to a display device.

In recent years, various display devices have been proposed which employ a so-called MIP (Memory-in-Pixel) system having a memory unit capable of storing data in pixels. In the case of a still image, MIP does not need to write image data each time, and therefore can realize ultra-low power consumption drive. For example, by combining with a reflective liquid crystal display technology, wearable devices and IOT (Internet of Things) devices can be used. By applying it to applications, a remarkable effect can be expected for long-term operation. On the other hand, since the data that can be held in the memory in the pixel is either 0 or 1, gray scale control cannot be performed by adjusting the voltage applied to the pixel electrode like a normal analog drive method, and white or black is not possible. There is a problem that it can only display. Therefore, when gradation display is performed in such a display device, one pixel or subpixel is divided into a plurality of display regions (segments) having different areas, and gradation display is performed by a combination of ON and OFF of these regions. The so-called area gradation method for realizing the above is adopted.

In a display device having an area gradation method, pixels or subpixel electrodes are divided according to the number of bits to be displayed. Specifically, when displaying n bits, a pixel or subpixel electrode is generally divided into n segments having an area ratio of 1, 2,... 2̂(n−1). .. Each segment has a corresponding memory portion, can hold data, and can perform gray scale display of 2 nth power by switching the white and black display of each area. For example, in the case of 2 bits, 2 squares in a segment having an area ratio of 1:2, that is, in the case where four gradations have an area ratio of 1:2:4 in the case of 3 bits, It is possible to express the third power of, that is, eight different gradations. However, it is known that if the segments to be divided are not arranged in an appropriate form, it is difficult to separate the segments from the adjacent pixels, which causes a problem in gradation display. In order to avoid this problem, a normal pixel in which sub-pixels (sub-pixels) displaying three primary colors of red (R; Red), green (G; Green), and blue (B; Blue) are arranged in a stripe pattern In this case, in the technique of displaying 2 bits with a structure in which each subpixel of RGB is divided into three, or in RGBW pixels composed of four subpixels to which another subpixel such as white (W; White) is added, A technique is known in which a bit segment is arranged near the center of a pixel electrode.

JP, 2014-021277, A JP, 2014-186283, A

However, when the sub-pixel is divided into three and two-bit display is performed with area gradation, it is necessary to add a new insulating layer and a wiring layer in order to electrically connect two separated electrodes. There are problems that the process becomes complicated and that the aperture ratio is reduced by dividing the pixel electrode into three. Further, in a method of arranging from a low bit segment in order from the center in a known manner as a known technique, for example, four sub-pixels of the same shape consisting of R, G, B and W are arranged in 2 rows and 2 columns. However, there is a problem in that it cannot be applied to pixels including three sub-pixels such as normal R, G, and B.

It is an object of the present invention to provide a means for reducing the load on the manufacturing process and performing area gray scale display having sufficient gray scale representation in a display device having three sub-pixels. ..

In order to achieve the above object, a display device according to the present invention includes a plurality of unit pixels arranged adjacent to each other, and the unit pixels are three sub-pixels arranged adjacent to each other and displaying different colors. Wherein each of the three sub-pixels is a display device having N display regions, and an N-bit area gradation display of each color is possible by a combination of the display regions. The display area corresponding to the least significant bit is rectangular, and the least significant bit display area of the sub-pixel that displays one color in one unit pixel is provided in either the same unit pixel or the adjacent unit pixel. The least significant bit display area of the subpixel of the unit pixel, which is in contact with the least significant bit display area of the subpixel that displays the other two colors. It is arranged so as not to contact the display area corresponding to the upper bits of the pixel.

According to the present invention, when the area gradation method is applied to a pixel configuration using three sub-pixels of RGB, for example, gradation expression with sufficient characteristics can be provided without increasing the load on the manufacturing process. it can. In the display device according to the present invention, at least one of the sub-pixels included in the unit pixel has a different shape from the other two, and one side of the unit pixel is shared by the three sub-pixels. The unit pixel is rectangular as a whole. As a result, it becomes possible to solve the problems of the conventionally known examples.

Further, when the display device according to the present invention intends to perform a semi-transmissive display, by providing a transmissive electrode in the same ratio as the area ratio of the reflective electrode, it is equivalent to the reflective display, and is excellent in the transmissive display. A tonal image can be displayed.

Further, the display device according to the present invention is provided with the interface for adjusting the input order of the data signals input to the segments, so that the RGB signals sent in the normal arrangement are directly received and the display device according to the pixel shape is received. Since the signal can be appropriately converted internally, it is possible to provide a means that does not impose a special load on the processor outside the display device.

FIG. 1 is a schematic view showing a cross section of a liquid crystal display device. FIG. 2 is a schematic diagram of the entire LTPS active matrix type TFT drive circuit. FIG. 3 is a schematic circuit diagram of a pixel portion of the MIP method. FIG. 4 is a diagram for explaining a conventionally known example of the area gradation method. FIG. 5 is a diagram illustrating the unit pixel PX according to the first embodiment of the present invention. The unit pixel PX according to the derivative form 1 of the first embodiment of the present invention will be described with reference to FIG. The unit pixel PX according to the derivative form 2 of the first embodiment of the present invention will be described with reference to FIG. 7. The unit pixel PX according to the derivative form 3 of the first embodiment of the present invention will be described with reference to FIG. The unit pixel PX according to the derivative form 4 of the first embodiment of the present invention will be described with reference to FIG. 9. A unit pixel PX according to the second embodiment of the present invention will be described with reference to FIG. 10. FIG. 11 shows the structure of the pixel electrode in the case of the semi-transmissive liquid crystal display device of the present invention. FIG. 12 shows a conventionally known example for explaining the data signal transmission order. FIG. 13 is a schematic diagram for explaining the data signal transmission order of the present invention. FIG. 14 shows a data control circuit and a timing chart for a conventional pixel array. FIG. 15 shows a data control circuit configuration for a pixel array disclosed in the present invention. Specific examples of electronic devices using the display device of the present embodiment will be described with reference to FIG. 16. With reference to FIG. 17, a specific example of an electronic device using the display device of this embodiment will be described.

Hereinafter, the present embodiment will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and a person having ordinary skill in the art can easily think of appropriate modifications while keeping the gist of the invention, and are naturally included in the scope of the invention. Further, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part as compared with the actual mode, but this is merely an example, and It does not limit the interpretation. In each figure, the same or similar elements arranged consecutively may be omitted from the reference numerals. Further, in the present specification and the drawings, constituent elements that exhibit the same or similar functions as those described above with respect to the already-existing drawings are designated by the same reference numerals, and redundant detailed description may be appropriately omitted. ..

In this embodiment, a liquid crystal display device is disclosed as an example of the display device. The display device can be applied to various devices such as a smartphone, a tablet terminal, a mobile phone terminal, a personal computer, a television receiver, an in-vehicle device, and a game machine. The main configuration disclosed in the present embodiment can be applied to a display device having an area gradation display unit other than the liquid crystal display device.

The description will be given in the following order.
1. Liquid crystal display device to which the present disclosure is applied 1-1. Semi-transmissive liquid crystal display device compatible with color display 1-2. Drive circuit configuration 1-3. MIP type liquid crystal display device 1-4. 1. In-pixel circuit of MIP type liquid crystal display device Description of Embodiment 2-1. Area gradation method 2-2. Pixel electrode for semi-transmissive display 2-3. Data signal transmission order and signal control circuit 3. Electronics

<1. Liquid crystal display device to which the present disclosure is applied>
The liquid crystal display device can be classified into a transmissive type, a reflective type, and a semi-transmissive type when classified according to a display form. The technique of the present disclosure is also applicable to a transmissive liquid crystal display device, but in practice, Suitable results can be obtained by mainly applying to the reflective and semi-transmissive liquid crystal display devices. The liquid crystal display device according to the present disclosure is an electronic device, in particular, a portable electronic device that is frequently used outdoors, that is, a mobile terminal device, for example, a mobile information device such as a digital camera or a mobile communication device such as a mobile phone. It is suitable for use as a display unit of.

A liquid crystal display device to which the present disclosure is applied includes a plurality of sub-pixels (sub-pixels) in one pixel (unit pixel) that is a unit for forming a color image. More specifically, in a display device compatible with color display, the unit pixel includes, for example, a sub-pixel that displays red (Red:R), a sub-pixel that displays green (Green:G), and a blue (Blue:B). Including three sub-pixels for displaying. However, the three sub-pixels are not limited to the three primary colors of RGB, and may be combinations such as cyan, magenta, and yellow. In any case, when the area gradation display is performed by the pixel including the three sub-pixels. Can be applied in.

[1-1. Semi-transmissive liquid crystal display device compatible with color display]
Hereinafter, as a liquid crystal display device to which the present disclosure is applied, a transflective liquid crystal display device compatible with color display will be described as an example with reference to the drawings. The present disclosure is not limited to the semi-transmissive liquid crystal display device, and can be applied to transmissive and reflective liquid crystal display devices.

FIG. 1 is a cross-sectional view showing a configuration example of a display device according to an embodiment. As shown in FIG. 1, the display device 13 includes a first panel 15, a second panel 14, and a liquid crystal layer 16. The second panel 14 is arranged so as to face the first panel 15. The liquid crystal layer 16 is provided between the first panel 15 and the second panel 14. The surface of the second panel 14 is a display surface 1a for displaying an image. Light incident from the outside on the display surface 1a side is reflected by the pixel electrode 9 of the first panel 15 and emitted from the display surface 1a. Further, the light emitted from the backlight unit 20 and incident from the first panel 15 side is also emitted from the display surface 1a. The display device 13 of the present embodiment is a semi-transmissive liquid crystal display device that displays an image on the display surface 1a using the reflected light and the transmitted light from the backlight. In the present specification, the direction parallel to the display surface 1a is the X direction, and the direction intersecting the X direction on the surface parallel to the display surface 1a is the Y direction. Further, the direction perpendicular to the display surface 1a is the Z direction.

The first panel 15 includes a first substrate 12, an insulating layer 11, a pixel electrode 10, and an alignment film 9. The transflective or transmissive liquid crystal display device has a quarter-wave plate 17, a half-wave plate 18, and a polarizing plate 19. As the first substrate 12, for example, a glass substrate or a resin substrate is used. On the surface of the first substrate 12, circuit elements (not shown) and various wirings such as gate wirings and signal wirings are provided. The circuit element includes a capacitive element and a switching element such as a TFT (Thin Film Transistor). The TFT may be formed of any of amorphous silicon (Amorphous Si), low temperature polysilicon LTPS (Low Temperature Poly Si), and transparent amorphous oxide semiconductor TAOS (Transparent Amorphous Oxide Semiconductor).

The insulating layer 11 is provided on the first substrate 12 and has a function of flattening the surfaces of circuit elements, various wirings, and the like. The pixel electrode 10 is provided on the insulating layer 11, and the alignment film 9 is provided between the pixel electrode 10 and the liquid crystal layer 16. The pixel electrode 10 may have a configuration in which a metal such as aluminum (Al) or silver (Ag), or a metal material thereof and a translucent conductive material such as ITO (Indium Tin Oxide) are used together. The metal material portion of the pixel electrode 10 functions as a reflection plate that reflects light incident from the outside.

The light reflected by the pixel electrode 10 travels toward the display surface 1a in a certain direction. The pixel electrode 10 is provided corresponding to each sub-pixel of R (red), G (green), and B (blue), and the liquid crystal layer 16 is changed by changing the voltage level applied to the pixel electrode 10. The retardation changes in, and as a result, the light transmission state is adjusted for each sub-pixel. That is, the pixel electrode 10 also has a function as a pixel electrode. Although the pixel electrode 10 and the insulating layer 11 are shown to be flat in FIG. 1, the surface of the insulating film 11 may be formed to have unevenness for diffuse reflection.

The second panel 14 includes a second substrate 4, a color filter 5, an overcoat 6, a common electrode 7, an alignment film 8, a quarter-wave plate 3, a half-wave plate 2, and a polarizing plate 1. Including and A color filter 5, an overcoat 6, and a common electrode 7 are provided on the surface of the second substrate 4 facing the first panel 15. An alignment film 8 is provided between the common electrode 7 and the liquid crystal layer 16. The quarter-wave plate 3, the half-wave plate 2, and the polarizing plate 1 are provided in this order on the surface of the second substrate 4 on the display surface 1a side. In this embodiment, the condition of the broadband circular polarizing plate made up of the combination of the quarter-wave plate 3 and the half-wave plate 2 is illustrated. I do not care. Although not illustrated in this embodiment, an isotropic or anisotropic diffusion layer is provided at a position adjacent to any one of the quarter wave plate 3, the half wave plate 2 and the polarizing plate 1. It may be one that has been submitted.

The second substrate 4 is a glass substrate or a resin substrate, and the common electrode 7 is formed of a translucent conductive material such as ITO. The common electrode 7 is arranged to face the plurality of pixel electrodes 9 and supplies a common potential to each sub-pixel. The color filter 5 has, for example, three filters of R (red), G (green), and B (blue), but may include four or more different color filters. The overcoat 6 is a flat insulating layer and is provided on the liquid crystal layer 16 side of the color filter 5.

The liquid crystal layer 16 is, for example, a nematic liquid crystal enclosed in a liquid crystal cell. In the liquid crystal layer 16, the voltage level between the common electrode 7 and the pixel electrode 10 is changed, so that the retardation of each sub-pixel is modulated, and as a result, the light of each sub-pixel is modulated.

Incident light entering from the display surface 1a side of the display device 13 passes through the second panel 14 and the liquid crystal layer 16 and reaches the pixel electrode 10. Then, the incident light is reflected by the pixel electrode 10. The light reflected by the pixel electrode 10 passes through the liquid crystal layer 16, is modulated for each sub-pixel, and is emitted from the display surface 1a. As a result, the image is displayed.

The backlight unit 20 used in the case of a transflective or transmissive liquid crystal display device is an illumination unit that illuminates the liquid crystal display panel from the back side thereof, that is, the side opposite to the liquid crystal layer 16 of the first panel unit 15. is there. The structure and constituent elements of the backlight unit 20 are not particularly limited, but for example, a light source such as an LED (Light Emitting Diode) or a fluorescent tube, and well-known members such as a prism sheet, a diffusion sheet, and a light guide plate. And can be used.

[1-2. Drive circuit configuration]
Before describing the embodiments of the present disclosure, a display device to which the technology of the present disclosure is applied will be described. Here, an active matrix liquid crystal display device will be described as an example of a display device to which the technique of the present disclosure is applied, but the display device is not limited thereto.

In FIG. 2, an outline of an LTPS (Low Temperature Poly Si) active matrix type TFT (Thin Film Transistor) drive circuit including a MIP drive circuit as a part thereof is described, and in FIG. To do.

The liquid crystal display device 13 according to this application example has a configuration including a pixel array section 30 in which pixels 21 are two-dimensionally arranged in a matrix, and a drive section arranged around the pixel array section 30. .. The drive unit includes a signal output circuit 35, a scanning circuit 40, a drive timing generation unit 45, and the like. For example, the drive unit is integrated on the same liquid crystal display panel (substrate) 11 as the pixel array unit 30. Each pixel 20 is driven. Here, in the liquid crystal display device 13 according to this application example, one unit pixel is composed of three sub-pixels, and each of these sub-pixels corresponds to the pixel 21. Therefore, in the configuration described below, the “sub-pixel” in the unit pixel is simply described as a “pixel”.

In FIG. 2, the signal lines 31-1 to 31-n (hereinafter, may be simply referred to as “signal line 31”) along the column direction with respect to the m-row by n-column pixel array of the pixel array unit 30. Are wired for each pixel column. In addition, scanning lines 32-1 to 32-m (hereinafter, sometimes simply referred to as “scanning line 32”) are laid out for each pixel row along the row direction. Here, the “column direction” refers to the arrangement direction of pixels in a pixel column, and the “row direction” refers to the arrangement direction of pixels in a pixel row.

Each one end of the signal line 31 (31-1 to 31-n) is connected to each output end corresponding to the pixel column of the signal line driving unit 35. The signal line drive unit 35 operates so as to output a signal potential reflecting a predetermined gradation to the corresponding signal line 31. Further, the signal line driving section 35 operates so as to output a signal potential reflecting a required gray level to the corresponding signal line 31 when the logic levels of the signal potentials held in the pixels 21 are exchanged. In FIG. 2, the scanning lines 32-1 to 32-m are shown as one wiring for one row of pixels, but actually, the number of scanning lines proportional to the number of bits is arranged. One end of each of the scanning lines 32-1 to 32-m is connected to each output end corresponding to the pixel row of the scanning line driving unit 40.

The drive timing generation unit (TG; timing generator) 45 generates various drive pulses (timing signals) for operating the signal line drive unit 35 and the scanning line drive unit 40, and supplies these to the drive units 35 and 40.

[1-3. MIP liquid crystal display device]
The display device of the present disclosure is a display device in which pixels having a memory function are arranged. As this type of display device, for example, a so-called MIP (Memory-in-Pixel) liquid crystal display device having a memory unit capable of storing data in a pixel can be exemplified. In addition, the idea of the present disclosure can be applied to a display device that uses a material having a memory property such as a ferroelectric liquid crystal, but in the following, the application to a MIP liquid crystal display device is considered first. And explain.

In the display device according to the embodiment of the present invention, one pixel (unit pixel), which is a unit for forming a color image, is configured by three sub-pixels. For example, R (red) G (green) B (Blue) 3 primary colors, etc. In the pixel of the MIP liquid crystal display device, the sub-pixel is further divided into a plurality of segments (display areas) according to the number of display bits, and in a segment corresponding to 1 bit, only two gradations of black and white are displayed. It is not possible to perform key expression. Therefore, as a gradation expression method, an area gradation method is used in which one subpixel is divided into a plurality of segments and gradation is displayed by a combination of areas of the plurality of segments. Here, the “area gradation method” is, as an example, N number of segments, that is, divided electrodes, in which the area ratio is weighted in the order of 2 ⁰ , 2 ¹ , 2 ² ,..., 2 ^N−1 . This is a gradation expression method for expressing 2N gradations.

In adopting the area gradation method, when the electrode of one sub-pixel is divided into a plurality of electrodes, the electrode of one sub-pixel is divided into, for example, two segments having different areas, and a segment having a small area is set as the minimum bit. It is possible to adopt a configuration in which a segment having a size twice as large as the area of the segment for displaying the smallest bit is the next bit, and by combining two segments, gradation display is performed with the largest bit. Each segment serves as an electrode, and the liquid crystal layer is also controlled according to the controlled potential based on the information stored in the memory. As a result, each segment has either a white or a black binary state.

[1-4. In-pixel circuit of MIP system]
FIG. 3 is a block diagram showing an example of a circuit configuration of each segment in subpixels forming a pixel in a MIP display device. Although illustration of the pixel electrode is omitted for simplification of the drawing, the liquid crystal capacitance 22 is the capacitance component of the liquid crystal material generated between the pixel electrode and the counter electrode formed facing the pixel electrode. The common voltage Vcom is applied to the counter electrode of the liquid crystal capacitor 22 commonly to all pixels.

As shown in FIG. 3, a pixel configuration with an SRAM (Static Random Access Memory) having three switch elements 23 to 25 and a latch section 26 is provided, and one end of the switch element 25 is connected to a signal line 31. There is. Data supplied from the signal line driving unit 35 via the signal line 31 is turned on (closed) by applying a scanning signal from the scanning line driving unit 40 via the scanning line 32 in FIG. Take in SIG. The latch unit 26 is composed of inverters 27 and 28 connected in parallel in opposite directions, and holds (latches) the potential according to the data SIG taken in by the switch element 25.

The potential V1 having the same phase as the common potential Vcom and the potential XV1 having the opposite phase to the common potential Vcom are applied to one terminal of each of the switch elements 23 and 24. The other terminals of the switch elements 23 and 24 are commonly connected and serve as an output node Nout of the pixel circuit. One of the switch elements 23 and 24 is turned on according to the polarity of the holding potential of the latch section 26. As a result, the in-phase potential V1 or the anti-phase potential XV1 is applied to the pixel electrode of the liquid crystal capacitor 21 to which the common potential Vcom is applied to the counter electrode, and white or black is displayed depending on the liquid crystal mode. It At the time of displaying a still image, since the information held in the latch unit 26 is used, it is not necessary to perform the write operation of the signal potential in the polarity inversion cycle of the liquid crystal layer, which has an advantage that power consumption can be reduced.

As described above, in the display device (that is, the active matrix type liquid crystal display device) 13 according to this application example, SRAMs (Static Random Access Memory) having the latch unit 26 that holds the potential according to the display data are arranged in a matrix. It is arranged. In this application example, the case where the SRAM is used as the built-in memory unit is described as an example. However, the SRAM is only an example, and a memory unit having another configuration, for example, a DRAM (Dynamic Random Access Memory) is used. It doesn't matter.

<2. Description of Embodiments>
[2-1. Area gradation method]
In the case of a display device having a memory function inside a pixel, for example, a MIP type liquid crystal display device, it is possible to display only two gradations per 1-bit segment. Therefore, the area gradation method is an effective means for providing richer gradation expression. Specifically, in the case of an application example of the present invention which is a color liquid crystal display device, the sub-pixel which is a constituent element of the pixel 21 is further divided into a plurality of area-weighted segments according to the number of display bits. The divided segment is composed of an electrode for electrically controlling the liquid crystal layer and a memory portion paired with the electrode.

In order to facilitate understanding, a conventionally known example is shown in FIG. 4 and its problems will be described. Specifically, an area gray scale method in which 4 gray scales are expressed by 2 bits by a segment obtained by dividing the area of one sub-pixel with a weight of 2:1 will be described as an example. Then, the configuration of the pixel according to the embodiment of the present invention will be described with reference to FIGS.

In FIG. 4A, a representative example of a conventionally known example in which a subpixel is divided into two is shown. Taking a sub-pixel displaying red (R) as an example, it is divided into two into a lower bit segment PR1 and an upper bit segment PR2 at an area ratio of 1:2. FIG. 4B shows a state in which the arranged pixels of FIG. 4A show different gray levels L0, L1, L2, and L3. Here, in all the segments, L0 indicates a black state and L3 indicates a white state. Here, when the pixels of the gradation L1 and the gradation L2 are adjacent to each other, the sum of the gradation L1 and the gradation L2 is exactly the same as the area of the pixel of the gradation L0, and thus it is difficult to distinguish them. Become. Therefore, it causes a problem of gradation display.

FIG. 4C shows an example in which the sub-pixel is divided into three among the conventionally known examples. Taking a sub-pixel displaying red (R) as an example, the point of PR1 which is a segment of lower bits and the segment PR2 which is an upper bit have an area ratio of 1:2, respectively. However, the difference is that PR2 is further divided into two. As a result, as shown in FIG. 4D, the adjacent pixels of the L1 and L2 gradations can be distinguished from the pixels of the L0 gradation, so that the problem of gradation display can be solved. However, in order to make the high-order bit into two segments with a large distance, it is necessary to branch the signal wiring to form a contact portion that electrically connects with each segment. The definition of is reduced. In order to solve this problem, a so-called multilayer wiring structure has been proposed, in which one insulating layer is added more than usual and connected with new wiring, but the problem of increasing the load on the manufacturing process Are listed.

FIG. 5A shows a configuration of a unit pixel PX according to the first embodiment of the present invention, which solves the above-described problem of the known example. The unit pixel PX has three adjacent subpixels, a subpixel PG that displays green (G), a subpixel PR that displays red (R), and a subpixel PB that displays blue (B). Color filters of colors corresponding to PG, PR, and PB are arranged to face the respective pixel electrodes. The unit pixel PX having a square shape is composed of sub-pixels having different shapes. As an example, as shown in FIG. 5A, the sub-pixel PG is a vertically long rectangle extending in the Y-axis direction, and the sub-pixel PR. The sub-pixel PB is a horizontally long rectangle extending in the X-axis direction. In FIG. 5A, the sub-pixel displaying green (G) is selected as a vertically long rectangle, but red (R) and blue (B) may be arranged instead.

Each sub-pixel has two segments having different areas in order to perform area gradation. The sub-pixel PG is the first segment PG1 having a small area and the second segment PG2 having a large area, the sub-pixel PR is the first segment PR1 and the second segment PR2, and the sub-pixel PB is the first segment. It has a segment PB1 and a second segment PB2, respectively. The area ratio of the first segment to the second segment is 1:2, and these two segments are combined so that the first segment is the low-order bit and the second segment is the high-order bit.

FIG. 5B is a diagram showing a state of gradation display according to the first embodiment of the present invention, in which L0 to L3 respectively represent gradation values, which means that the brightness increases in this order. To do. The gradation value L0 is black in all the segments of the unit pixel PX, the gradation value L1 is white in the segments PG1, PR1 and PB1 and the rest is black, and the gradation value L2 is in the segments PG2, PR2 and PB2. Is white and the rest is black, and the gradation value L3 is such that all the segments of the unit pixel PX display white. It should be noted that the state in which the "segment displays black" here means that the segment is off, and in the case of a reflective liquid crystal display device, the light reflected by the reflective electrode cannot go out of the display device. Equivalent to. Further, the state in which the “segment displays white” corresponds to the state in which the segment is on, and the state where the light reflected on the electrode passes through the corresponding color filter layer and exits. In addition, here, for simplification, the segments in the sub-pixels PR, PG, and PB are interlocked with each other and described in the same state, but it is also possible to change the state independently in each sub-pixel.

Since the lower-bit segments PR1, PG1, and PB1 are all surrounded by the higher-bit segments PR2, PG2, and PB2, adjacent pixels and lower-bit segments do not contact each other. Therefore, as shown in FIG. 5B, the adjacent pixels of the L1 and L2 gradations can be distinguished from the pixels of the L0 gradation, so that the above-described gradation display problem can be solved. Further, in the case of 2-bit display for each color, it is not necessary to divide one subpixel into three segments as in the conventionally known example of FIG. 4C, and it is sufficient to divide it into two. It is not necessary to add an insulating layer for connection, and the manufacturing process can be performed in the conventional manner.

6 and 7 show derivative forms 1 and 2 of the first embodiment of the present invention. Compared with the first embodiment of the present invention shown in FIG. 5A, the sub-pixel PG has a vertically long rectangle extending in the Y-axis direction, and the sub-pixels PR and PB have a horizontally-long rectangle extending in the X-axis direction. Is common, but differs in that the lower-order bit segments PR1, PG1, and PB1 are elongated rectangles. As shown in FIGS. 6B and 7B, the adjacent pixels of the L1 and L2 gradations can be discriminated from the pixels of the L0 gradation, so that the problem of the gradation display described above should be solved. Can be done. Note that, as an example, the sub-pixel displaying green (G) is selected as a vertically long rectangle, but red (R) and blue (B) may be arranged instead.

FIG. 8 shows a derivative form 3 of the first embodiment of the present invention. As shown in FIG. 8A, the unit pixel PX is a square, two sub-pixels, here, PR and PG are L-shaped, and the remaining sub-pixel PB is a vertically long rectangle. Also in this configuration, as can be seen from FIG. 8B, the lower-bit segments PR1, PG1, and PB1 are arranged so as to be sandwiched by the upper-bit segments PR2, PG2, and PB2. It is possible to avoid the problem of gradation display due to.

FIG. 9 shows a derivative form 4 of the first embodiment of the present invention. As shown in FIG. 9A, the unit pixel PX is a square, and includes two L-shaped sub-pixels (here, PR and PB) and the remaining rectangular sub-pixels (here, PG). The difference from the pixel of FIG. 8 is that a rectangular sub-pixel is surrounded by two L-shaped sub-pixels and is not in contact with an adjacent pixel. As can be seen from FIG. 9B, since the lower-bit segments PR1, PG1, and PB1 do not contact adjacent pixels, it is possible to avoid the problem of gradation display.

FIG. 10 shows a second embodiment of the present invention. As shown in FIG. 10A, the unit pixel PX is composed of rectangular sub-pixels PR, PG, and PB, and the lines connecting the respective center points are arranged in a delta array that is a triangular array. As can be seen from FIG. 10B, since the lower-bit segments PR1, PG1, and PB1 are arranged so as to be sandwiched by the upper-bit segments PR2, PG2, and PB2, gradation display due to the influence of adjacent pixels is displayed. It is possible to avoid the problem of.

[2-2. Pixel electrode for semi-transmissive display]
FIG. 11 illustrates the configuration of the pixel electrode in the case of a semi-transmissive liquid crystal display device as one embodiment of the present invention. FIG. 11A shows the configuration of the first embodiment shown in FIG. 5, in which PG1_T, PG2_T, PR1_T, PR2_T, PB1_T, PB2_T are transparent transparent electrodes, PG1_R, PG2_R, PR1_R, PR2_R, PB1_R, and PB2_R represent reflective metal electrodes. The transparent electrode and the reflective metal electrode in one segment are electrically connected to each other with some overlap at the end, and the potential is changed in conjunction with the electric signal supplied from one contact hole CH, Controls the liquid crystal layer. Here, in the case of a 2-bit area gradation pixel for each color, in addition to the areas of the segments in one sub-pixel being divided at a ratio of 1:2, the transparent electrode portion and the reflective metal electrode portion are both 1 By dividing at a ratio of :2, it is possible to perform desired gradation display that works in both transmissive display and reflective display.

Although the illustration and explanation of all the configurations of the first and second embodiments of the present invention shown in FIGS. 5 to 10 will be omitted, in any configuration, a semi-transmissive liquid crystal display device is used. When applied, the above embodiment can be adopted. That is, the transparent electrode and the reflective metal electrode in one segment are electrically connected to each other with some overlap at the end, and the potential changes in conjunction with the electric signal supplied from one contact hole CH. Then, the liquid crystal layer is controlled. Further, the pixel configurations of the first and second embodiments of the present invention are not limited to the transflective liquid crystal display device, and may be applied to a reflective liquid crystal display device.

[2-3. Data signal transmission order and signal control circuit]
12 and 13, the data signal transmission order and the control circuit for the signal will be described for the embodiment of the present invention. FIG. 12 is a conventional known example illustrated for comparison, and FIG. 13 is an example showing the case of the embodiment of the present invention, and representatively illustrates the case of the first embodiment. Each segment has a corresponding memory circuit section 50, and data is exchanged through the signal line 31 when the scanning line 32 is controlled to be open.

In the case of a conventionally known example, as shown in FIG. 12A, upper bit and lower bit segments of the same color are arranged in the Y-axis direction, that is, in the direction parallel to the signal line 31, and the memory circuit unit corresponding to each segment. 50 is also arranged in the same order. Therefore, as shown in FIG. 12B, the data signal 51 is sequentially transmitted through one signal line, such as data RL for lower bits and data RH for higher bits of the same color.

In the embodiment of the present invention, unlike the conventionally known example, the upper bit and the lower bit segment of the same color are not necessarily arranged in the Y-axis direction, that is, parallel to the signal line 31. As shown in FIG. 13A, since the red (R) and blue (B) sub-pixels PR1, PR2 and PB1, PB2 are arranged in the X-axis direction, the corresponding memory circuit section 50 is also the same. Has become. Therefore, as for the data signal 52, as shown in FIG. 13B, it is necessary to send data of subpixels of different colors through one signal line.

It is also possible to input the data rearranged in such an order into the display device after being converted on the MPU side of the electronic device, but the electronic device side sends a conventional signal and rearranges the data on the display device side. Is more convenient when viewed from the electronic device side. Therefore, in order to explain the method of converting the data arrangement in the display device, FIG. 14 discloses a conventional data control circuit for pixel arrangement, and FIG. 15 discloses the present invention which realizes data rearrangement in the display device. 2 shows a data control circuit configuration for a pixel array.

In the case of the conventional pixel array data control circuit shown in FIG. 14A, the shift register SR is synchronized so that the image signals sent to the display device as serial data are sequentially stored in the memory holding unit LAT1. To operate. When the data storage for one row of the display device is completed, the data is collectively written in the next second memory holding unit LAT2. Therefore, the potential is adjusted to a predetermined value, and then information is written to the memory in the segment in the sub-pixel that constitutes the pixel. A timing chart of the above circuit operation is shown in FIG.

In the case of the circuit for controlling the data rearrangement for the pixel array disclosed in the present invention in the display device shown in FIG. 15, a data interchange section DE is newly added as compared with the configuration of FIG. , The number of line memories has been doubled. By doing so, the signals normally sent in the order of R, G, and B can be appropriately exchanged according to the pixel array of the present invention. A timing chart of the above circuit operation is shown in FIG.

<3. Electronics>
16 and 17 specifically show examples of electronic devices using the display device of the present embodiment. FIG. 16 shows an example in the case of a laptop computer, which uses the display device of the present embodiment to ensure a certain level of image quality and is significantly lower than the case of using a conventional transmissive liquid crystal display. It becomes possible to realize power consumption reduction. In the case of the tablet shown in FIG. 17 as well, since it is a portable type, it is desired to reduce the power consumption for long-term use. Even in this case, by adopting the display device of the present embodiment for the screen SCR, It is possible to bring out a remarkable effect.

As described above, according to this embodiment, it is possible to provide a display device capable of improving display quality and saving power.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

1 Polarizing Plate 2 1/2 Wave Plate 3 1/4 Wave Plate 4 Second Substrate 5 Color Filter 6 Overcoat 7 Common Electrode 8 Alignment Film 9 Alignment Film 10 Pixel Electrode 11 Insulating Film 12 First Substrate 13 Display Device 14 Second Panel 15 First panel 16 Liquid crystal layer 17 1/4 wave plate 18 1/2 wave plate 19 Polarizing plate 20 Back light section 21 Pixel 22 Liquid crystal capacity 23 Switch elements 24, 24, 25 Switch element 26 Latch section 27, 28 Inverter 30 Pixel array section 31 Signal line 32 Scan line 35 Signal output circuit 40 Scan circuit 45 Drive timing generation section 50 Memory circuit section 51, 52 Data signal Vcom, V1, XV1 Potential Nout Output node PR1, PG1, PB1 Lower bit Segments PR2, PG2, PB2 Lower-order bit segments L0, L1, L2, L3 Grayscale PX Unit pixels PR, PG, PB Sub-pixel blue PG1_T, PG2_T, PR1_T, PR2_T, PB1_T, PB2_T Transparent transparent electrode PG1_R, PG2_R, PR1_R, PR2_R, PB1_R, PB2_R Reflective metal electrode
CH Contact hole SR Shift register LAT1, LAT2 Memory holding section DE Data exchange section SCR screen

Claims (6)

A plurality of unit pixels arranged adjacent to each other,
The unit pixel includes three sub-pixels arranged adjacent to each other to display different colors,
The three sub-pixels are display devices each having N display regions,
It is possible to display an area gradation of N bits for each color by combining the display areas.
Of the display area, the display area corresponding to the least significant bit is a square,
The least significant bit display area of a sub-pixel that displays one color in one unit pixel is a sub-pixel that displays two other colors provided in either the same unit pixel or an adjacent unit pixel. The least significant bit display area is in contact with the least significant bit display area, and the least significant bit display area of the subpixel of the unit pixel is not in contact with the display area corresponding to the upper bit of the subpixel of the same color of the adjacent unit pixel. , Display device arranged as.
In the sub-pixel included in the unit pixel,
At least one has a different shape from the other two,
In addition, the one side of the unit pixel is arranged so as not to be shared by the three sub-pixels,
The display device according to claim 1, wherein the unit pixel has a rectangular shape as a whole.
The display device according to claim 1, wherein the plurality of unit pixels are arranged by repeating a delta arrangement in which a line connecting center points of the three subpixels arranged adjacent to each other is a triangle.
Each of the N display regions in the sub-pixel is
A reflective area made of a reflective metal electrode,
With a transparent area consisting of transparent transparent electrodes,
The transflective liquid crystal display device according to claim 1, wherein an area ratio of the N reflective areas and the transmissive area is equal to an area ratio of the N display areas.
A first storage unit that holds signal data for one row of the display device, a replacement unit for the data held in the storage unit, and the data replaced by the replacement unit are stored in the first storage unit. The display device according to any one of claims 1 to 4, further comprising a second storage unit having a number twice that of the storage unit.
A plurality of unit pixels arranged adjacent to each other,
The unit pixel includes three sub-pixels arranged adjacent to each other to display different colors,
The three sub-pixels are display devices each having N display regions,
It is possible to display an area gradation of N bits for each color by combining the display areas.
Of the display area, the least significant bit display area corresponding to the least significant bit is a square,
The least significant bit display area of a sub-pixel that displays one color in one unit pixel is a sub-pixel that displays two other colors provided in either the same unit pixel or an adjacent unit pixel. The least significant bit display area, which is in contact with the least significant bit display area and is the least significant bit display area of the sub-pixel of the unit pixel, corresponds to the most significant bit of the sub-pixel of the same color of the adjacent unit pixel. An electronic device including a display device arranged so as not to come into contact with the electronic device.