JP2006053497A - Color display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color display device which makes various color displays including the three primary color display with simple wiring. <P>SOLUTION: The pixels 50 of the color display element is composed of the 1st subpixels 52 to make color display by using a modulation area based on the hue changes of the medium, and the 2nd subpixels 51 having one of the red, green, and blue filters. The 1st subpixels 52 are modulated in the hue variation range of the medium to display color, and the 2nd subpixels 51 are modulated in the lightness variation range of the medium to display the color of the filter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color display device capable of displaying a plurality of colors.

  Conventionally, the segment type display element can be used to easily display numerical values and simple alphabets, and thus is widely used as a display unit of various devices such as a wristwatch, a thermometer, a weight scale, a tester, a calculator, and a remote controller. In addition to such numerical display, it is also widely used for various character displays such as an icon display indicating the remaining battery level and the radio wave status of the mobile phone.

  Here, as a display element used for this, there are a light emitting type such as an LED, or a non-light emitting type using a liquid crystal. Among them, a direct drive type reflective display element using a liquid crystal has low power consumption. It is the most widely used because it can be driven with a dry battery for a long time.

  The most widely used direct drive reflective display element using this liquid crystal is a TN liquid crystal display in which a TN mode liquid crystal is sandwiched between two polarizing plates and a reflector is provided on the back. It is an element.

  Here, in this TN type liquid crystal display device, two upper and lower polarizing plates are orthogonally crossed, and a nematic liquid crystal that is parallel to a pair of glass (or plastic) substrates with a transparent electrode and twisted by 90 degrees is sandwiched therebetween. It is a thing of composition.

  With this configuration, light is transmitted through the liquid crystal layer when no voltage is applied, and the transmitted light is reflected by the reflector on the back surface, and can pass through the liquid crystal layer again to obtain a bright display. . On the other hand, when a voltage is applied to the liquid crystal layer, the liquid crystal molecules are aligned perpendicular to the substrate, so that the incident light cannot pass through the polarizing plate on the back side, and the light does not reach the reflector, resulting in a dark display. Can be obtained. In this way, it is possible to switch between a state in which the background color (generally white) and display color contrast exist and a state in which no contrast exists, and a highly visible monochrome display can be obtained. .

  Next, a structure of a monochrome 7-segment display device which is an example of a liquid crystal display device using a display element that performs such monochrome display will be described with reference to FIG.

  In FIG. 9, an electrode provided on one of a pair of substrates (not shown) corresponds to a segment electrode corresponding to each of the seven segments 61 to 67, and an electrode provided on the other substrate is a common electrode. It corresponds to.

  Then, a pulse voltage is applied to the common electrode, and the voltage applied to the common electrode by the common electrode control unit 69 is applied to the segment electrode corresponding to the segment for which black display is to be obtained by the segment electrode control unit 68 as a control signal. By applying a reverse-phase voltage, a state in which a pulsed electric field is continuously applied between the electrodes is realized.

  Moreover, the state which does not apply an electric field between electrodes is implement | achieved by applying the voltage in phase with the voltage applied to a common electrode to the segment electrode corresponding to the segment which wants to obtain white display. In this way, a bright and dark monochrome display can be obtained.

  On the other hand, in a color LCD (liquid crystal display device) used for a PC monitor or a liquid crystal television, it is possible to display three primary colors and mixed colors by providing a color filter for a monochrome display element.

  By the way, in the display device having the conventional direct drive type reflective display element which is widely used because of such features such as simple driving and low power consumption, the reflective type, the transmissive type and the LED display have been used so far. In view of the above, the present situation is that a product capable of displaying multiple colors has not been realized.

  However, this is not because there is no need for colorization. This is because, by coloring characters and numerical values that are directly driven, it is possible to give meaning to the display, and it is possible to give great value to the product itself.

  For example, when it is applied to a thermometer display, for example, a blue numerical value is displayed when it is less than 37 degrees, a yellow value is displayed when it is 37 to 38 degrees, and a red numerical value is displayed when it is 38 degrees or more. It may be easier. Moreover, color display of numerical values and characters is considered effective from the viewpoint of barrier-free and universal design.

  In order to colorize, for example, in a reflective TN-LCD, if a simple color filter is used, an object having a thickness such as glass or a polarizing plate exists between the liquid crystal layer and the reflector. Parallax will occur. As a result, the reflected light passes through a color filter of a different color from the color filter through which incident light passes, and as a result, a very dark display is obtained. In order to avoid such a phenomenon, a reflection display mode of a single polarizing plate type in which a reflection plate is provided on the inner side of glass may be applied (for example, see Non-Patent Document 1). Alternatively, there is no problem if it is a transmissive display mode.

  Further, in the conventional monochrome display element, when three types of color filters of R (red), G (green), and B (blue) are provided for one segment or character, the color filter of such a color display element is used. As shown in FIG. 10, if one segment (or character) is simply divided into three as shown in FIG. 10, the shape of the segment (or character) changes during color display.

  In order to avoid such a phenomenon, as shown in FIG. 11, stripe color filters of R, G, and B are alternately arranged in the horizontal direction, and the same type of color filters are simultaneously driven. Even when color display is performed in various display colors, the shape can be prevented from changing.

  Here, considering the electrode connection of these three kinds of stripe color filters R, G, and B, the electrode connection is laid out to minimize the wiring length as shown in FIG. One of a method of using a multilayer wiring structure to prevent a short circuit between electrodes due to electrode overlap and a method of laying a wiring between stripe electrodes as shown in FIG. 13 to avoid the multilayer wiring can be considered.

Japan Display '86 p. 312: K.M. Tadokoro et al.

  However, in the conventional color display element having such a configuration, the cost increases as compared with the conventional monochrome type in any connection method. There is concern that the yield will decrease, so it is not suitable for mass production.

  In particular, in the connection method shown in FIG. 13, since it is necessary to provide a black stripe in order to conceal the wiring part between the stripe electrodes, the aperture ratio is greatly reduced, and the optical loss and aperture ratio decrease due to the color filter. The loss of both results in a very dark display. Furthermore, there is a concern about display unevenness due to electrode resistance.

  Therefore, as a configuration for solving such problems, for example, instead of using three types of RGB color filters, only two of RGB or only one of RGB color filters, A method in which the number of electrodes to be controlled is two types by combining a color filter and a color filter having a complementary color relationship is conceivable.

  And by comprising in this way, a simple wiring structure as shown in FIG. 6 mentioned later can be taken. This eliminates the need for wiring such as multilayer wiring and stripe electrodes as described above, so that it is possible to suppress yield problems during manufacturing, reduction in aperture ratio, and display unevenness.

  However, when only two of RGB are used as the color filter, only two primary colors among the three primary colors can be displayed, and at the same time, white display cannot be performed. Further, when any one of RGB and its complementary color is combined, white display is possible, but only one of the three primary colors can be displayed. That is, in any case, only a limited display color can be expressed, and the change in display color such as blue, yellow, and red cannot be realized as described in the example of the thermometer.

  In addition, when the color filter is disposed only on the electrode as in the configuration used in a normal color LCD, a state in which the background color matches the display color cannot be obtained. Can't get.

  Accordingly, the present invention has been made in view of such a situation, and an object of the present invention is to provide a color display device that can display various colors including three primary colors with a simple wiring structure.

  The present invention uses a medium having a lightness change range in which the lightness is changed by the modulation means and a hue change range in which the hue is changed by the modulation means, and a color display device including a color display element having a plurality of pixels. A first sub-pixel that performs color display on the pixels of the color display element using a modulation region based on a hue change of the medium, and a first sub-pixel that is provided with any one of red, green, and blue color filters. Two subpixels, and electrodes for inputting color output signals to the two subpixels, respectively, and inputting the color output signal from the modulation means to the electrodes, The first subpixel is subjected to modulation of the hue change range of the medium to display a chromatic color, and the second subpixel is subjected to modulation of the brightness change range of the medium. It is characterized in that to display the color of the serial color filter.

  As in the present invention, a plurality of pixels of a color display element are provided with a first subpixel that performs color display using a modulation region based on a hue change of a medium, and any one color filter of red, green, and blue The second subpixel is composed of two subpixels, the first subpixel is modulated in the hue change range of the medium to display a chromatic color, and the lightness of the medium is displayed on the second subpixel. By displaying the color of the color filter by applying the modulation of the change range, it is possible to perform multicolor display including the three primary colors with a simple wiring structure.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. Before that, a color display device capable of performing color display without using the color filter which is the basis of the present invention will be described. A color liquid crystal display device using an ECB type (electric field control birefringence effect type) liquid crystal display element as an example will be described.

  As the ECB type liquid crystal display element, a transmissive type and a reflective type, in which a liquid crystal cell having a medium between a pair of substrates is sandwiched and polarizing plates are arranged on the front side and the back side, respectively. In addition, the reflective type is a single polarizing plate type in which a polarizing plate is disposed only on one substrate, and two polarizing plates are disposed on both substrates and a reflecting plate is provided outside the polarizing plate. There is a polarizing plate type.

  Here, for example, in the case of a transmissive ECB type liquid crystal display element, linearly polarized light that is transmitted through one polarizing plate is polarized by the birefringence of the liquid crystal layer in the process of passing through the liquid crystal cell. The light becomes elliptically polarized light with different states, the light is incident on the other polarizing plate, and the light transmitted through the other polarizing plate corresponds to the ratio of the light intensity of each wavelength light constituting the light. Colored colored light.

  Thus, the ECB type liquid crystal display element colors light by utilizing the birefringence action of the liquid crystal and the polarization action of the polarizing plate, and does not absorb the light by the color filter. Can be increased to obtain a bright color display. Moreover, since the birefringence of the liquid crystal layer changes according to the voltage, the color of transmitted light or reflected light can be changed by controlling the voltage applied to the liquid crystal. If this is used, a plurality of colors can be displayed in the same segment.

  FIG. 1 shows the relationship between the birefringence amount (referred to as retardation R) of such an ECB type liquid crystal display element and the coordinates on the chromaticity diagram. According to FIG. 1, R ranges from 0 to about 250 nm. Is almost achromatic in the center of the chromaticity diagram, but it can be seen that the color changes according to the amount of birefringence beyond that.

  In this case, a material having a negative dielectric anisotropy (expressed as Δε) is used as the liquid crystal. When such a liquid crystal is aligned vertically with respect to the substrate when no voltage is applied, the liquid crystal molecules As the liquid crystal tilts, the amount of birefringence (called retardation) of the liquid crystal increases.

  At this time, under crossed Nicols, the chromaticity changes along the curve of FIG. That is, when no voltage is applied, R is almost 0, so light is not transmitted and is in a dark state (black state). However, as the voltage increases, the brightness increases from black to gray to white. . When the voltage is further increased, the color changes, and the color changes, such as yellow → red → purple → blue → yellow → purple → light blue → green.

  Thus, the ECB type liquid crystal display element can change the brightness between the maximum brightness and the minimum brightness by the voltage in the modulation region on the low voltage side, and can change a plurality of hues by the voltage in the higher voltage region. Can do.

  In the following, the retardation range (0 to 250 nm) in which the brightness changes from black to gray to white on the chromaticity diagram is referred to as the brightness change range, and the chromatic color change range above yellow (250 nm or more) is referred to as the hue change range. . Since the boundary between the achromatic color and the chromatic color cannot be determined clearly, the above range of 250 nm is a rough standard.

  In the present invention, a color obtained by retardation is mentioned, which is a color along the curve of FIG. As shown in FIG. 1, the point where the purity is maximized has retardations near 450 nm, 600 nm, and 1300 nm, and is visually recognized as red, blue, and green. However, since there is a range that can be regarded as substantially the same color with a width of about 100 nm before and after these points, the colors in the range are also called red, blue, and green in the present invention. Magenta is in the vicinity of 530 nm between red and blue.

  Furthermore, the color of the color filter used in a liquid crystal display device or the like is usually more pure than the color obtained by retardation, and is outside the above range on the chromaticity diagram. In the present invention, these are also called by the same color.

  Although the ECB type liquid crystal display element can display color, in order to display green, a retardation amount of about 1300 nm is required as shown in FIG. 1, and when a normal liquid crystal material is used, it is compared with a conventional liquid crystal display element. Therefore, a considerably large cell thickness is necessary.

  For example, a liquid crystal element known as a VA (Virtual Alignment) mode is set to be vertically aligned in a no-voltage applied state, and the maximum retardation amount is changed to about 200 to 250 nm by applying a voltage. The brightness change region from black to white at is used. A full color display is obtained by an additive color mixing method by providing an RGB color filter.

  Compared with this, in the method of performing color display using the ECB effect, that is, the change in chromaticity due to retardation, the cell thickness needs to be set to about 6 times if the liquid crystal material is the same. That is, if the cell thickness of a product using the current VA mode is 4 to 5 microns, a cell thickness of 20 to 30 microns is necessary in the color display mode using the coloring phenomenon due to the ECB effect.

  Next, an embodiment of the present invention will be described.

  FIG. 2 is a diagram showing a structure of one pixel of a color liquid crystal display element which is an example of a color display element used in a color liquid crystal display apparatus which is an example of a color display apparatus according to the first embodiment of the present invention. .

  In FIG. 2, reference numeral 50 denotes a segment (or character) that is a pixel, and this segment 50 is divided into two sub-segments (or sub-characters) 51 and 52. Each of the sub-segments 51 and 52 may be composed of a plurality of sub-segments and driven simultaneously.

  Here, a green color filter G is disposed in one of the sub-segments 51. The color filter G is disposed on a transparent electrode denoted by reference numeral 137 in FIG. 7 described later. The other sub-segment 52 is not provided with a color filter. In this sub-segment 52, the retardation is adjusted to change the luminance of an achromatic color from black to white, and from blue to magenta. Or any color from green to green.

  That is, in the present embodiment, the first segment 50 displays the chromatic color by changing the retardation of the liquid crystal layer by applying a voltage corresponding to the color output signal by the modulation means capable of controlling the power source (not shown) for the one segment 50. A second sub-segment which has a first sub-segment 52 as a sub-pixel and a green color filter G, and displays the color of the color filter, that is, green (G), by changing the retardation in the brightness change range by applying a voltage. The second sub-segment 51 is a pixel.

  Then, as in the present embodiment, a green color filter G is disposed on the second sub-segment 51 to display green with high visibility, and the first sub-segment 52 is red due to a coloring phenomenon caused by ECB. And blue are displayed.

  With this configuration, for example, when displaying white, the second sub-segment 51 (hereinafter referred to as the G segment) 51 with the green color filter G is in a dark state, and the first sub-segment without the color filter is used. By making the sub-segment (hereinafter referred to as a transparent segment) 52 white (the maximum luminance state of the achromatic color change region), white can be displayed as a whole segment. Alternatively, the G segment 51 may be set to a substantially maximum transmission state, and the transparent segment 52 may be set to a magenta color in a chromatic color region. In this case, since the magenta color includes both red (R) and blue (B) colors, white display is obtained as a result of the synthesis.

  In order to display a single G color, the G segment 51 is set to the maximum transmission state, and the transparent segment 52 is set to the dark state. Further, in order to display R single color (B single color), the G segment 51 is set in the dark state, and the retardation value of the transparent segment 52 is set to 450 nm (600 nm). Furthermore, a color mixture of R and G and B and G can be obtained by combining these. Furthermore, it goes without saying that if the G segment 51 and the transparent segment 52 are both darkened by setting the retardation to 0, a black display can be obtained.

  In the present embodiment, the G segment 51 changes the retardation in the range of 0 to 250 nm, and the transparent segment 52 changes the retardation in the range of 0 to 250 nm and the range of 450 nm to 600 nm. In general, since the liquid crystal material is common to both the sub-segments 51 and 52, the drive voltage ranges are set differently.

  Here, when the green color filter G is provided as in the above example, it is avoided to make green by adjusting the retardation, so that it is not necessary to increase the cell thickness. In addition, since green has high visibility, a color filter can produce a high-purity color, which is effective for increasing the number of colors.

  In addition, by performing color display with a color filter, even if the color display state due to retardation changes slightly changes due to temperature change or viewing angle, there is a clear difference between the color of the color filter part and the color part due to retardation. It will be planned. Therefore, the risk of erroneous operation is reduced even when various users use it based on the barrier-free.

  In addition, such a color filter may be disposed in the background portion other than on the 50 electrodes. When the color filter is disposed in this way, the display state in a state where no voltage is applied to the liquid crystal layer is obtained. Since they match on the electrode and the background portion, it is possible to obtain a display state with high visibility where the presence or absence of display contrast can be clearly seen.

  According to the present embodiment, as described above, for example, one color such as the G segment 51 is displayed by the color filter, and the other colors are displayed by colors generated by the medium (in the above case, liquid crystal) itself. However, the present invention can be applied to media other than liquid crystals. That is, in general, if a medium whose optical properties are changed by a modulation means applied from the outside is used and the medium has a modulation area whose brightness is changed by the modulation means and a modulation area whose hue is changed, the present invention is used. Is applicable.

  Here, when such a medium is used, for example, a display element is configured using such a medium, and a unit segment is composed of a transparent first sub-segment and a second sub-segment having a color filter. Constitute. Then, the first sub-segment is modulated such that the hue changes in a predetermined range to display the color in the range, and the second sub-segment is modulated in the lightness change range to adjust the brightness of the color of the color filter. By changing the height, color display is performed. In this case, in order to display black, gray, and white achromatic colors, the lightness change range may be modulated on the transparent first sub-segment.

  The retardation value is for a transmissive liquid crystal display element arranged under crossed Nicols, but when this is applied to a reflective liquid crystal display element, the cell thickness is halved and the response speed is reduced to ¼. In addition to speeding up, the manufacturing process is close to the cell thickness setting with other LCDs, which contributes to improved yield.

  As described above, the color liquid crystal display element according to the present embodiment employs a display method using a coloring phenomenon based on the ECB effect for, for example, red and blue, and therefore when using red and blue color filters respectively. Compared with the optical loss, the optical loss can be greatly reduced. As a result, it is a feature that an element with high light utilization efficiency can be obtained as compared with the conventional method of displaying the three primary colors using only the RGB color filter.

  On the other hand, the liquid crystal display element having such a configuration has a high transmittance of the liquid crystal layer even as a transmissive liquid crystal display element, and therefore requires less backlight power consumption to obtain the same brightness as that of the conventional method. It is preferably used from the viewpoint of low power consumption.

  So far, for example, an analog gradation has been realized by using the color filter G for green display, and a coloring phenomenon based on the ECB effect has been described for red and blue. An example of using a color filter for blue and an example of using a color filter for blue are considered.

  By the way, at least one color filter of red, blue, and green is disposed in the second sub-segment 51, and the first sub-segment 52 is complementary to the color filter disposed in the second sub-segment 51. A color filter may be provided. And by comprising in this way, in a segment (or character) display, a display with higher color purity is attained.

  Next, for such a second embodiment of the present invention, for example, a green color filter is disposed in the second sub-segment 51, and a magenta color filter that is a complementary color of green is disposed in the second sub-segment 51. The case where it arrange | positions is demonstrated.

  For example, when a color filter is not used for the first sub-segment 52 as in the first embodiment described above, yellow → yellow red → red → purple in the range of the retardation amount exceeding the white region. (Magenta) → purple → blue violet → blue shows a change in color tone. By arranging a magenta color filter in the first sub-segment 52 like this embodiment, red and blue color reproduction is performed. The range can be greatly expanded.

  FIG. 3 is a diagram showing the structure of one segment (pixel) of the color liquid crystal display element used in the color liquid crystal display device according to the present embodiment. The G segment 51 is the same as that of the first embodiment described above. A green color filter G is disposed, and a magenta color filter M is disposed in the first sub-segment 52.

  In the present embodiment, as in the first embodiment, the second sub-segment (G segment) 51 is modulated in the modulation region that changes the brightness of the liquid crystal, thereby changing the green brightness. On the other hand, the first sub-segment 52 is given a modulation of the modulation region that changes the hue of the liquid crystal to display a chromatic color, and is also given a modulation of the modulation region that changes the lightness to change the lightness of the magenta color. Display.

  FIG. 4 shows a calculated value of color change due to retardation when an ideal magenta color filter having a transmittance of zero to 580 nm to 580 nm and a transmittance of other wavelengths of 100% is provided. Indicates. As apparent from FIG. 4, in the first sub-segment 52, as the retardation amount increases from zero, the black display is changed to a dark magenta (magenta halftone) to a bright magenta display. It shows the change of brightness in various chromatic colors.

  Further, after this, the amount of retardation further increases, and when the retardation amount exceeds the white region in the example where no color filter is used for the first sub-segment 52, magenta → red → purple (magenta). It shows a continuous change of chromatic colors such as → purple → blue.

  When this is compared with FIG. 1, the range of chromaticity change extends to near the red and blue pure colors (the corners of the chromaticity diagram), and the magenta color filter M is arranged in the first sub-segment 52. It can be seen that the red and blue color reproduction range is expanded. It can also be seen that since the change from red to blue moves along the lower side of the chromaticity diagram, a continuous color change from red to blue is obtained. As described above, by arranging the magenta color filter M, the color reproduction range of red and blue is expanded, and at the same time, a continuous change of the intermediate color is obtained when the retardation is changed.

  For example, in this embodiment, in order to display white, both the first sub-segment (hereinafter referred to as magenta segment) 52 and the G segment 51 are set to the same retardation value (250 nm) that gives the maximum transmittance. Alternatively, the G segment 51 may be set to a substantially maximum transmittance state (in the vicinity of a retardation value of 250 nm), and the magenta segment 52 may be set to an intermediate retardation value of red and blue (in the vicinity of 550 nm).

  In the case of the former method, in order to change the lightness of the achromatic color, the retardation of the magenta segment 52 is changed in accordance with the retardation of the G segment 51 so that the gradations of both the sub-segments 51 and 52 change together. You can do it. In addition, when displaying each color of black display, G, R, and B, displaying those mixed colors is the same as that of the first embodiment.

  As described above, when the green color filter G is used, by using the magenta color filter M having a complementary color relationship with green, an achromatic gradation can be expressed, and at the same time, the gradation of the green complementary color can be obtained. Since it can be expressed, the number of display colors that can be expressed can be greatly increased. Of course, since it is possible to continuously change the hue of red and blue, it is possible to obtain more display colors by combining these display colors with the G segment 51. Further, since the magenta color filter M transmits both red and blue, a bright display can be obtained as compared with the conventional method in which the red and blue color filters are provided.

  In addition to the VA mode in which the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the substrate surface when no voltage is applied, and the retardation is changed by tilting from the substantially vertical alignment when a voltage is applied, there are various types described below. Applicable to liquid crystal display mode.

  In the OCB (Optically Compensated Bend) mode, the liquid crystal molecules in the liquid crystal layer change the retardation by changing the alignment state between the bend alignment and the substantially vertical alignment by applying a voltage, and therefore the present invention can be applied to the VA mode. It is the same.

  Further, in this configuration, in order to use the display color due to the retardation change, the color tone change due to the viewing angle must be considered. However, recent advances in LCD development are remarkable, and it is no exaggeration to say that the problem of viewing angle dependency is almost solved in color liquid crystal displays using the RGB color filter system. For example, in the OCB mode, it is reported that the retardation change accompanying the change in the viewing angle is suppressed by the self-compensation effect by the bend alignment. In addition, the viewing angle characteristics of the STN mode are greatly improved due to the development of the retardation film.

  Since the OCB and STN modes can obtain a coloring phenomenon based on the ECB effect by appropriately setting the retardation amount, the configuration of the present invention can be applied. In particular, in the OCB mode, since the response speed described above can be greatly improved, the OCB mode is preferably used in applications that require high speed.

  On the other hand, the MVA (Multidomain Virtual Alignment) mode has already been commercialized and widely used as a mode exhibiting very good viewing angle characteristics. In addition, a mode called a PVA (Patterned Virtual Alignment) mode is also widely used.

  These vertical alignment modes achieve a wide viewing angle characteristic by controlling the liquid crystal molecule tilt direction during voltage application by making the surface uneven (MVA) or devising the electrode shape (PVA). . Since these are modes in which the amount of retardation is changed by voltage, the configuration of the present invention can be applied. By doing so, it is possible to realize a liquid crystal display element that simultaneously satisfies high transmittance (or reflectance), a wide viewing angle, and a wide color space. In addition to these, various liquid crystal modes such as a parallel alignment ECB mode and a HAN mode having a vertically asymmetric pretilt can be applied.

  In the description so far, green having high visibility is handled independently, and the other primary colors are displayed using the coloring effect due to birefringence in segments other than green. As described above, this is the most advantageous for the display performance of natural images, but it is not necessarily limited to green, but red is treated as an independent segment, and blue and green are utilized by the birefringence coloring effect. A display method or a method in which blue is treated as an independent segment and red and green are displayed using a coloring effect by birefringence may be used.

  In addition, as described above, a medium whose optical properties are changed by a modulation signal applied from the outside is used, and the medium has a modulation area whose brightness is changed by a modulation means and a modulation area whose hue is changed. If so, the present invention can be applied to various display elements without being limited to liquid crystal elements. For example, a display mode in which the thickness of the interference layer is mechanically changed by an external modulation means, an electrophoretic display element that can control different display colors in a unit segment by using electrophoretic particles of multiple colors, etc. Can give.

  FIG. 5 is a diagram showing a structure of a liquid crystal display device which is an example of a liquid crystal display device including the liquid crystal display element according to the first or second embodiment described above, and this liquid crystal display device has seven segments. (Or character) 61-67. A color output signal is inputted to each of the seven segments (or characters) 61 to 67 through a wiring configuration as shown in FIG.

  A color output signal is input to each of the segments (or characters) 61 to 67, and a color output signal is controlled by a modulation means (not shown), thereby enabling multicolor display including three primary colors. It is possible to add value to various devices. Needless to say, not only seven-segment display but also multi-color display is possible in character and icon display, and an added value is given.

  In this manner, the hue change range of the medium such as liquid crystal is modulated on the first sub-segment 52 to display red and blue by the coloring phenomenon by ECB, and the lightness change range of the medium is displayed on the second sub-segment 51. By applying modulation to display green, which is the color of the color filter, it is possible to perform multicolor display including three primary color displays only by controlling the color output signal. As a result, multi-color display including three primary color displays can be performed with a simple wiring structure. In addition, since a color filter is also provided in the background portion, display with high visibility can be performed.

(Example)
Next, the display element of this invention is explained in full detail using Examples 1-15. In this embodiment, when a color filter is used for the first sub-segment 52 (see FIG. 2), magenta is used as the color filter color and used for the second sub-segment 51 (see FIG. 2). Assume that green is used as the color filter.

  Here, the common structure of the liquid crystal display element as an example of the color display element used in Examples 1 to 15 is as follows.

  As a structure of the liquid crystal layer, two glass substrates subjected to vertical alignment treatment are superposed to form a cell, and a liquid crystal material having a negative dielectric anisotropy Δε as a liquid crystal material (manufactured by Merck, model name: MLC-6608) Is used. At this time, the cell thickness is changed so as to optimize the retardation according to the embodiment.

  As a substrate structure to be used, one substrate is a substrate on which a desired electrode and a color filter are patterned, and the other substrate is a substrate having a light-reflective common electrode. The electrode shape and color filter configuration at this time are changed according to the embodiment.

  In addition, a phase compensation such as a broadband λ / 4 plate (a phase compensation plate that can substantially satisfy the ¼ wavelength condition in the visible light region) between the upper substrate (color filter substrate) and the polarizing plate according to the embodiment. A board is placed. By changing the retardation amount used at this time, it is possible to control the display state when no voltage is applied in the reflective display.

Example 1
As shown in FIG. 2 described above, the segment configuration of the liquid crystal display element used in the first embodiment is that one unit segment 50 is divided into two sub-segments 51 and 52, and one sub-segment 51 is divided among them. Only a green color filter is provided, and the remaining one sub-segment 52 is not provided with a color filter. Note that the color filter G exists only on the segment electrode.

  FIG. 7 is a sectional view of such a liquid crystal display element. In FIG. 7, reference numeral 130 denotes a reflective liquid crystal element. 131 is a linear polarizing plate, and 132 is a λ / 4 plate. At this time, in order to satisfy the λ / 4 condition over the entire visible light region, the λ / 2 plate and the λ / 4 plate may be used in combination using a known method, and the wavelength dispersion characteristic is controlled. Alternatively, a λ / 4 plate may be used. 133 is a forward scattering plate, and 134 and 142 are glass or plastic substrates. Note that a transparent substrate is necessary for 134, but 142 is not necessarily transparent.

  A color filter 135 is formed in a necessary region. Reference numeral 136 denotes a planarizing layer, which is used to eliminate a level difference that occurs when a color filter is present or not, or when different types of color filters are used. Reference numeral 137 denotes a transparent electrode such as ITO, and 138 and 140 denote alignment films. In this embodiment, a vertical alignment film is used. In addition, rubbing is applied in the antiparallel direction to align the liquid crystal molecule tilt direction when voltage is applied.

  Reference numeral 139 denotes a liquid crystal layer. In the liquid crystal layer 139, the liquid crystal molecules are inclined by about 1 degree from the normal direction of the substrate when no voltage is applied by the rubbing process. Reference numeral 141 denotes an electrode having light reflectivity, such as aluminum or silver. The layer thickness (cell thickness) of the liquid crystal layer of the liquid crystal display element 130 was 5 microns. At this time, the retardation amount when a ± 5 V voltage is applied to the transparent sub-segment without the color filter is about 300 nm.

  And about such a liquid crystal display element, the display state was changed by changing a voltage. First, when no voltage is applied, black is displayed in any segment. Further, with respect to the sub-segment having the green color filter, the transmittance change according to the applied voltage value is shown in the region of 3V or less, and the continuous tone characteristic is obtained.

  On the other hand, with respect to the other transparent sub-segments, blue is displayed when 5 V is applied, and red is displayed when 3.8 V is applied. Thus, it can be seen that the liquid crystal element of the present example displays three primary colors. Further, in an area of 3 V or less, a monochrome continuous tone corresponding to the magnitude of the applied voltage is displayed.

  This makes it possible to perform a 7-segment display capable of displaying the three primary colors. In the present embodiment, the portion other than the electrodes (segment peripheral portion) where no voltage is applied is always displayed in black, and a numerical display showing various display colors is provided on the black background.

  In addition, the mixed colors of the display colors can be displayed by variously changing the display colors displayed on the two sub-segments. Thereby, white / black and RGB three primary colors and YMC display can be performed. In addition, a great number of display colors can be obtained by combining continuous tone regions.

(Example 2)
The segment configuration of the liquid crystal display element used in the second embodiment is the same as that in the first embodiment, and one unit segment is divided into two sub-segments, and a green color filter is provided in one sub-segment. In addition, a magenta color filter is disposed in the remaining one sub-segment. The cell thickness of this element was 5 microns. At this time, the amount of retardation when a ± 5 V voltage is applied to the sub-segment having the magenta color filter is about 300 nm. The color filter exists only on the segment electrode.

  When such a liquid crystal display element is displayed by changing the voltage, the sub-segment having a green color filter shows a change in transmittance according to the applied voltage value in the region of 3 V or less, Tonal characteristics can be obtained. On the other hand, other sub-segments having a magenta color filter are blue when 5V is applied and red when 3.8V is applied, and thus it can be seen that the liquid crystal panel of this embodiment is the three primary color display. Further, in an area of 3 V or less, a magenta continuous tone corresponding to the magnitude of the applied voltage is displayed. In addition, a high color purity at this time can be obtained.

  In this way, it is possible to perform a 7-segment display capable of displaying three primary colors with high color purity. In other words, a numerical display showing various display colors with high color purity is made on a black background.

  In addition, the mixed colors of the display colors can be displayed by changing the display colors displayed on the two sub-segments in various ways. Thereby, white / black and RGB three primary colors and YMC display can be performed. In addition, a great number of display colors can be obtained by combining continuous tone regions.

(Example 3)
In the third embodiment, in the configuration of the first and second embodiments, a color filter is provided in a portion other than the electrode. And by comprising in this way, the brightness of the black display state at the time of no voltage application becomes uniform, and a display element with high uniformity can be obtained.

Example 4
In the present Example 4, it was set as the same structure except having excluded (lambda) / 4 used for Examples 1-3. At this time, the color filter is disposed only on the electrode.

  And in this Example 4, since only a linear polarizing plate is used for the liquid crystal element, when the amount of retardation of the liquid crystal layer is almost zero in the state where no voltage is applied, the incident polarized light is reflected by the reflective electrode, In order to emit light while maintaining the polarization state as it is, white display is performed in the state where no voltage is applied.

  In addition, when the voltage is about 3 V and the retardation of the liquid crystal layer is about λ / 4, black is displayed, and when the voltage is further increased, white is displayed again. Obtainable. That is, the same effect can be obtained even in the white display mode when no voltage is applied.

(Example 5)
In the configuration of Example 4, when observed when no voltage is applied, only the portion corresponding to 7 segments is displayed slightly dark, and there is a possibility that the user may be concerned that the display is erroneous. Therefore, in the fifth embodiment, by providing a color filter in a portion other than the electrodes, the overall brightness when no voltage is applied can be made uniform, and the possibility of erroneous operation can be avoided.

(Example 6)
In addition to the configurations used in Examples 1 to 3, the display color when no voltage is applied can be changed to various ones by applying a retardation plate having another large retardation value.

  In this example, when a phase difference plate having a retardation of 300 nm is added and observed, blue display can be obtained in a state where no voltage is applied. Other colors can be obtained by changing the above values to other values. As a result, a device with high designability can be obtained by using this color segment display element, for example, by matching the housing color and the segment background color. In this case as well, it is possible to obtain a display element with higher uniformity by disposing a color filter in addition to the electrodes.

(Example 7)
In FIG. 5 described above, the direction of the stripe color filter (stripe pattern) on the 7 segments is almost the same as the direction of connection, and is in the horizontal direction. However, in this embodiment, as shown in FIG. Patterning is performed so that the direction of the (striped pattern) is parallel to the long side (longitudinal) direction of each of the seven segments.

  As a result, electrode extraction can be realized with a simple pattern, so that concerns such as disconnection and short circuit are reduced. Thereby, it is only necessary to determine which pattern direction is adopted according to the manufacturing process, which contributes to the improvement of the yield.

(Example 8)
In Example 8, a 7-segment color display element is used for calculator display. In this case, for example, if the calculation result is set to a red value when the calculation result is a negative value, a calculation error is reduced.

Example 9
In the ninth embodiment, the 7-segment color display element is used for a weight scale capable of obtaining a body mass index (BMI) from a preset height and a measured weight. The BMI can be obtained from (weight (kg) ÷ height (m) ² ).

  In this case, when the BMI value deviates from the prescribed value, the weight display can be displayed in color to help maintain health. It is also effective to display in color when the body fat percentage exceeds a specified value, which is considered useful for dieting and the like.

(Example 10)
In the tenth embodiment, a 7-segment color display element is used for tester display. In this case, for example, in an existing tester, a result is obtained by a beep sound for an open / short check, but the measurement can be performed in a quiet experimental environment by displaying this in color. In addition, when measuring resistance values, units such as Ω, KΩ, MΩ, and GΩ may be misunderstood, but measurement errors can be prevented by changing the display color of the numerical values that are displayed according to the unit change. it can.

(Example 11)
In the eleventh embodiment, the contact driving type color display element is applied to an indicator icon indicating the remaining battery level of the notebook PC. In this case, it is possible to prevent the loss of data due to running out of the battery by effectively warning the user by displaying the red color when the remaining battery level is low.

(Example 12)
In the twelfth embodiment, the direct drive type color display element is applied to an indicator icon indicating a radio wave condition of a mobile phone. In this case, a mobile phone with high design can be obtained.

(Example 13)
In Example 12, a 7-segment color display element is used for displaying a wristwatch. In this case, for example, the schedule time is set, and the time display color is changed as the schedule approaches, so that the schedule is not overlooked.

(Example 14)
In Example 14, a 7-segment color display element is used for remote control display for an air conditioner. In this case, for example, even when the set temperature is 23 ° C., it is possible to know at a glance whether the setting is the heating setting, the cooling setting, or the dry setting, which can lead to an energy saving effect.

(Example 15)
In Example 15, a 7-segment color display element is used for display for a rice cooker. In this case, for example, the state during cooking is understood at a glance. In addition, for example, when the use is exceeding a specified value, such as when the heat retention time exceeds 24 hours, a warning can be displayed, which can contribute to prevention of food poisoning.

  As described above, the added value of the product can be greatly increased by using the color display device of the present invention. In this embodiment, the liquid crystal is mainly described. However, instead of the liquid crystal element having the ECB effect, a mode in which a gap distance which is a thickness of air as a medium of the interference layer is changed by mechanical modulation is used. However, the same effect as the present embodiment can be obtained.

  Further, even when a particle movement type display element that moves a plurality of particles that are media based on the configuration described in the embodiment by applying a voltage is used as the color display element, the same effect as in this embodiment can be obtained.

  In this embodiment, the combination of green and magenta (or green and transparent) is described as the color filter, but the combination of red and cyan (or red and transparent) and blue and yellow (or blue and transparent) is also applicable. It is.

The figure showing the color tone change when the retardation change of the liquid crystal display element used for this invention is carried out. 1 is a diagram showing a structure of one pixel of a color liquid crystal display element which is an example of a color display element used in a color liquid crystal display apparatus which is an example of a color display apparatus according to a first embodiment of the present invention. The figure which shows the structure of 1 segment (pixel) of the color liquid crystal display element used for the color liquid crystal display device which concerns on the 2nd Embodiment of this invention. The figure showing the color tone change when the retardation of the liquid crystal display element is changed. FIG. 5 shows a structure of a liquid crystal display device using the liquid crystal display element. The figure which shows the wiring of seven segments of the said liquid crystal display device. Sectional drawing of the liquid crystal display element used for Example 1 of this invention. The figure which shows the structure of the 7 segment liquid crystal display device which concerns on Example 7 of this invention. The figure which shows the structure of the conventional monochrome 7 segment display element. The figure which shows the example which divided the color filter provided in the conventional monochrome display element into three. The figure which shows the example which divided | segmented the color filter provided in the conventional monochrome display element into plurality. The figure which shows the wiring of the unit segment of the conventional RGB color filter system. The other figure which shows the wiring of the unit segment of the conventional RGB color filter system.

Explanation of symbols

50 segments (characters)
51 Second sub-segment 52 First sub-segment 61 to 67 Seven segments 130 Reflective liquid crystal element 135 Color filter 137 Transparent electrode G Green color filter M Magenta color filter

Claims (9)

In a color display device using a medium having a lightness change range in which the lightness is changed by the modulation means and a hue change range in which the hue is changed by the modulation means, and including a color display element having a plurality of pixels,
A first sub-pixel that performs color display on the pixels of the color display element using a modulation region based on a hue change of the medium, and a second color filter provided with any one of red, green, and blue color filters. And two subpixels of the subpixel,
Each of the two subpixels is provided with an electrode for inputting a color output signal, and the color output signal from the modulation means is input to the electrode, whereby the hue change range of the medium is modulated on the first subpixel. And displaying the chromatic color and modulating the brightness change range of the medium to the second subpixel to display the color of the color filter.   The color display device according to claim 1, wherein the color filter is also disposed in a background portion of the pixel.   2. The color according to claim 1, wherein each of the first and second sub-pixels includes a plurality of stripe patterns, and the stripe patterns of the same type are connected to the electrodes and driven simultaneously. Display device.   The color display device according to claim 3, wherein a direction of the stripe pattern and a connection direction of the stripe pattern substantially coincide with each other.   The color display device according to claim 3, wherein a direction of the stripe pattern substantially coincides with a long side direction of the pixel.   The color display element includes at least one polarizing plate, a pair of substrates that are arranged to face each other by patterning electrodes, and a liquid crystal layer that is disposed between the substrates. The unit pixel of the color display element includes a plurality of sub-pixels, and the plurality of sub-pixels change the retardation of the liquid crystal layer by applying a voltage, thereby chromatic color. And a second sub-pixel having a color filter and displaying a color of the color filter by changing a retardation in a brightness change range according to a voltage. The color display device according to any one of 1 to 5.   The color display element has a function of changing a color tone of an interference color by arranging a plurality of metal thin films on at least a substrate and modulating a gap distance which is a thickness of air as a medium between the metal thin film and the substrate. And at least one of the plurality of pixels includes a first sub-pixel capable of performing color display based on a hue change according to a change in interference color due to a change in gap distance, and a second filter having a color filter layer. The color display device according to claim 1, comprising: a sub-pixel.   The color display element moves a plurality of particles as a medium by applying a voltage, and at least one of the plurality of pixels has at least two or more drive electrodes and at least two or more kinds of different particle movement characteristics. 7. The color display device according to claim 1, comprising: a first subpixel including particles exhibiting coloration; and a second subpixel having a color filter layer. 8. A color display device configured using a medium having a brightness change range for changing the brightness of incident light by a modulation applied from the outside and a hue change range for changing the hue,
The display device includes a background region in which the medium exhibits a certain optical state, and a modulation region that is embedded in the background region in a predetermined pattern and the medium is modulated to exhibit a different optical state, A color display device, wherein the background region and the modulation region each include a first sub-pattern portion and a second sub-pattern portion having a color filter.

Images