JP2005345661A - Display device and large display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device using a cholesteric liquid crystal, with which a gray scale is displayed and further in which contrast is not lowered, and to provide a large display device using the same. <P>SOLUTION: The display device is equipped with a display device 111 using the cholesteric liquid crystal, a characteristics determining part to determine whether image data displayed on the display device 111 include three or more gray scales, and a characteristics determining part to determine the driving conditions of the display device 111, using a first characteristic of the cholesteric liquid crystal, when the image data include three or more gray scales as decideded by the characteristics deciding part, and using a second characteristic of the cholesteric liquid crystal in the case the image data include less than three gray scales. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device and a large display device using the display device, and particularly relates to a display device including a display device using a cholesteric liquid crystal and a large display device using the display device.

  As a typical configuration of a large display device, a display module is configured by mounting a drive circuit on each display device, and the display modules are arranged in a matrix. However, it is necessary to arrange the display modules close to each other so that the joint between the display devices does not stand out in a tile shape. In each display module, a part of an image divided in accordance with the size of the display module is displayed, and one image is displayed on the entire display module arranged in a matrix.

  Conventionally, CRT (Cathode Ray Tube), PDP (Plasma Display Panel), VFD (Vacuum Fluorescent Display), LCD (Liquid Crystal Display), and the like are widely used as display devices in this type of large display device. In particular, various types of devices such as TN mode LCDs, STN mode LCDs, and TFT-LCDs are used in LCDs.

  However, due to the characteristics of the display element, the above display device cannot perform display unless a predetermined drive is always performed. For this reason, even an image having no change such as a still image needs to be driven at all times and consumes power. On the other hand, a display device using a cholesteric liquid crystal having a memory operation mode is attracting attention because it does not need to be driven to hold a displayed image and can reduce power consumption. As shown in Patent Document 1, practical application of a display device using a cholesteric liquid crystal has been studied.

  Next, the operation of a display device using cholesteric liquid crystal will be described. The display device corresponds to the direction of twist when the twisted central axis (helical axis) of the cholesteric liquid crystal sandwiched between a pair of parallel substrates is aligned perpendicularly to the substrate on average. It has the property of reflecting the circularly polarized light. This phenomenon is called selective reflection, and a liquid crystal array that exhibits this selective reflection is called a planar alignment.

  On the other hand, as a liquid crystal alignment different from the planar alignment, it is possible to take an arrangement called a focal conic arrangement in which the twist axes of liquid crystals are arranged in a random direction or a non-perpendicular direction with respect to the substrate in a plurality of domains. . The focal conic arrangement shows a weak scattering state and does not reflect light of a specific wavelength unlike selective reflection.

  Cholesteric liquid crystal changes the planar arrangement to a focal conic arrangement or the focal conic arrangement to a planar arrangement by applying a pulsed voltage between substrates and controlling the magnitude of the applied voltage amplitude (applied voltage value). Can be made. The change from the focal conic alignment to the planar alignment occurs via a liquid crystal alignment (referred to as homeotropic) in which the liquid crystal molecules are substantially parallel to the electric field application direction, and therefore the highest applied voltage is required. The above contents are described in detail in, for example, Patent Document 2.

  A display device using a cholesteric liquid crystal changes an alignment state by controlling an applied voltage, controls reflection of external light, and displays an image. In order to effectively represent the image to be displayed, it is important to improve the ratio of the reflectance between the white display and the black display of the displayed image, that is, the contrast.

Japanese Patent Laid-Open No. 14-14324 Japanese Patent Laid-Open No. 14-202495

  A display device using a cholesteric liquid crystal shows a high reflectance when the applied voltage value (amplitude of the applied voltage waveform) is from 0 V to a certain voltage value, but when the voltage exceeds a certain voltage value, the reflectance decreases. Go. Even if the voltage value applied from there is increased, the reflectance remains low, but after applying a certain voltage value, when the voltage application is suddenly stopped (the voltage value is reduced to zero), a high reflectance is exhibited. It becomes like this. That is, a display device using a cholesteric liquid crystal has a voltage-reflectance characteristic (hereinafter also referred to as a left side characteristic) in which the reflectance decreases when the applied voltage is increased, and a voltage-reflectance in which the reflectance increases when the applied voltage is increased. Characteristics (hereinafter also referred to as right-side characteristics).

  The left-side characteristics described above are used to display halftones necessary for expressing a full-color image in a display device using a cholesteric liquid crystal because the change in reflectance with respect to an applied voltage is gradual. ing. However, when using the left side characteristic, the longer the voltage application time to the cholesteric liquid crystal, the lower the white display reflectance and the lower the contrast.

  On the other hand, the right characteristic is not suitable for halftone display because the change in reflectance with respect to the applied voltage is steep, but the reflectance of white display does not decrease even if the voltage application time to the cholesteric liquid crystal is long. Contrast does not decrease. That is, when the left side characteristic is used, there is a problem that the contrast is lowered as compared with the case where the right side characteristic is used.

  However, in the display device using the right side characteristic, the image representation uses a pure color, and halftone cannot be used, so that a full color image cannot be sufficiently expressed. Conventional display devices are configured to use either the left-side or right-side characteristics of voltage-reflectance characteristics in advance. Select whether to sacrifice contrast or halftone display. There was a need to do.

  Accordingly, the present invention has been made to solve the above problems, and provides a display device using cholesteric liquid crystal capable of halftone display and causing no reduction in contrast, and a large display device using the same. The purpose is to provide.

  The solving means according to the present invention includes a display device using a cholesteric liquid crystal, a characteristic determining unit that determines whether image data displayed on the display device is a first image characteristic or a second image characteristic, When the characteristic determination unit determines that the image data has the first image characteristic, the driving condition of the display device is determined using the first characteristic of the cholesteric liquid crystal, and is determined to be the second image characteristic. A characteristic determination unit that determines a driving condition of the display device using the second characteristic of the cholesteric liquid crystal.

  The display device according to the present invention and the large display device using the same determine whether the image data has the first image characteristic or the second image characteristic, and based on the result, determine the characteristic of the cholesteric liquid crystal. Since the selection and the driving conditions of the display device are determined, it is possible to provide a display device using a cholesteric liquid crystal capable of halftone display and causing no reduction in contrast, and a large display device using the same. .

(Embodiment 1)
FIG. 1 shows a schematic diagram of a display device according to the present embodiment. The display device shown in FIG. 1 includes a display module 11 on which a display device using cholesteric liquid crystal is mounted, and a display control unit 12 that transmits image data to the display module 11 and performs control.

  Here, the image data is data that constitutes one image by configuring each pixel of red, green, and blue corresponding to the three primary colors of light as one pixel and arranging the pixels as a minimum unit in a matrix. It is. On the other hand, a display device using cholesteric liquid crystal is configured to display all pixels of image data. For example, in a standard generally known as XGA (eXtended Graphics Array), the image data is composed of a matrix of horizontal 1024 pixels and vertical 768 pixels, and this XGA image data is displayed on one display module 11. When trying to do so, a display device using cholesteric liquid crystal needs to be composed of 1024 pixels in the horizontal direction and 768 pixels in the vertical direction.

  FIG. 2 is a block diagram of the display device according to this embodiment. In addition, the code | symbol in a figure respond | corresponds with the code | symbol of FIG. The display control unit 12 illustrated in FIG. 2 includes a drive condition control unit 121 and an image data storage unit 122. The drive condition control unit 121 has a function of determining drive conditions necessary for displaying an image on the display module 11 and transmitting image data. Specifically, the drive condition determined by the drive condition control unit 121 includes a pulse width of an applied voltage waveform supplied to the display device. The image data storage unit 122 stores image data to be displayed on the display module 11 in advance, and transmits optimal image data to the drive condition control unit 121.

  Next, the display module 11 determines a cholesteric liquid crystal display unit 111 that is a display device using cholesteric liquid crystal, a voltage value (amplitude of an applied voltage waveform) to be applied to the cholesteric liquid crystal display unit 111, and supplies the applied voltage. And a display driving unit 13. The display drive unit 13 includes an image characteristic determination unit 131 and a drive unit 132.

  The image characteristic determination unit 131 analyzes the image data received from the drive condition control unit 121 and determines whether to drive the cholesteric liquid crystal display unit 111 using the left side characteristic or the right side characteristic. FIG. 3 shows voltage-reflectance characteristics of a display device using cholesteric liquid crystal. In FIG. 3, the horizontal axis represents the applied voltage value (unit V), and the vertical axis represents the reflectance (unit%). In FIG. 3, when the voltage value applied to the display device using the cholesteric liquid crystal is from 0 V to a certain voltage value, the reflectance is high, and when the voltage value exceeds a certain voltage value, the reflectance is lowered, and a higher voltage is applied. It is shown that when the voltage application is suddenly stopped after application (the voltage value is made zero), high reflectance is exhibited.

  The drive unit 132 generates and drives a voltage to be applied to the cholesteric liquid crystal display unit 111 based on the result from the image characteristic determination unit 131 and the image data and the drive condition from the drive condition control unit 121. The cholesteric liquid crystal display unit 111 displays a desired image by the applied voltage supplied from the driving unit 132. The cholesteric liquid crystal display unit 111 and the display driving unit 13 are configured as one display module 11.

  FIG. 4 is a block diagram of the display driving unit 13 according to the present embodiment. FIG. 5 is a flowchart of the image characteristic determination unit 131 according to the present embodiment. The operation of the display device according to the present embodiment will be described with reference to FIGS. First, the image characteristic determination unit 131 according to the present embodiment includes a characteristic determination unit 21 and a characteristic determination unit 22 as shown in FIG.

  The characteristic determination unit 21 receives the image data transmitted from the drive condition control unit 121 (step AS1 in FIG. 5), and analyzes the gradation information used in the image data (step AS2). Here, when the image data is expressed as 24-bit full color bitmap data, each pixel of red, green, and blue has 8 bits, that is, 256 kinds of gradation information from 0 to 255. In this analysis, all the pixels of the received image data are analyzed.

  The analysis in step AS2 analyzes which gradation of 256 types of gradation information each pixel of the image data is. Based on the analyzed information, whether the image data includes halftone (gradation other than 0 gradation or 255 gradation) or only pure color (0 gradation or 255 gradation) It is determined by the characteristic determination unit 21 (step AS3). Here, when it is determined that the pixel data is composed only of the pure color, the pixel data has only two kinds of gradation information of the 0 gradation and the 255 gradation, or one of the 0 gradation and the 255 gradation is one. This is either case of having only type of gradation information.

  However, even in the case of image data including halftones, for example, image data including only two types of halftones of 100 gradations and 200 gradations is handled in the same manner as image data composed only of pure colors. However, the information contained in the image does not deteriorate. Further, by converting 100 gradations to 0 gradations and 200 gradations to 255 gradations, the contrast of the image data is improved. Therefore, in the present embodiment, when it is determined that the image is composed only of pure colors, it is sufficient that the image data includes gradations of two gradations or less. That is, the image data including only two types of halftones of 100 gradations and 200 gradations is determined by the characteristic determination unit 21 according to the present embodiment to include only pure colors.

  On the other hand, when all the pixels of the image data are analyzed to have three or more gradations, it is determined that the image data is an image including a halftone.

  Next, the characteristic determination unit 22 shown in FIG. 4 receives the determination result transmitted from the characteristic determination unit 21, and uses either the left side characteristic or the right side characteristic of the voltage-reflectance characteristic shown in FIG. It is determined whether to drive the display unit 111. When the image data includes halftones, that is, when it is determined in step AS3 that the image data includes three or more gradations, the cholesteric liquid crystal display unit 111 is driven using the left side characteristic. When the image data includes only pure colors, that is, when it is determined in step AS3 that the image data includes gradations of two gradations or less, the cholesteric liquid crystal display unit 111 is driven using the right side characteristic.

  Next, the characteristic determination unit 22 determines an applied voltage value (amplitude of the applied voltage waveform) of each pixel of the image data based on the determined result of the characteristic (left or right characteristic) of the cholesteric liquid crystal (step AS6). . Specifically, when driving using the left characteristic, the reflectance of the left characteristic is divided into 256 gradations, and the applied voltage value corresponding to the gradation of the image to be displayed is determined. For example, the applied voltage value is selected and determined according to the gradation in the range of 10V to 30V.

  In the case of driving using the right side characteristic, it is determined to be either an applied voltage value for a transmission mode with a low reflectance or an applied voltage value for a reflection mode with a high reflectance. For example, the applied voltage value is selected and determined as either a transmission mode of 30 V or a reflection mode of 50 V. In the case of driving using the right side characteristic, each pixel has only two kinds of gradations, so that the cholesteric liquid crystal display unit 111 displays eight colors at the maximum.

  After the applied voltage value to the cholesteric liquid crystal display unit 111 is determined by the characteristic determining unit 22, the applied voltage value is sent to the drive unit 132 (step AS7). The drive unit 132 supplies a voltage to the cholesteric liquid crystal display unit 111 based on the drive conditions (such as the pulse width of the applied voltage waveform) received from the drive condition control unit 121 and the applied voltage value, and displays a desired image.

  As described above, when the image displayed on the cholesteric liquid crystal display unit 111 is a full-color image including a halftone such as a photograph, the color is frequently used by driving using the left side characteristic of the voltage-reflectance characteristic of FIG. In the case of illustrations and characters including gradations of two gradations or less, driving using the right characteristic of the voltage-reflectance characteristic of FIG. 3 and driving using the left characteristic. A better contrast can be obtained as compared with the case of the above. In other words, by controlling the characteristics of the cholesteric liquid crystal in accordance with the characteristics of the image, it is possible to perform an expression most suitable for the image to be displayed.

  In FIG. 1, the display module 11 and the display control unit 12 are separated, but the present invention is not limited to this, and the display control unit 12 is incorporated in the display module 11 so that the above functions can be combined into one module. good. In this embodiment, the case where the image data includes three or more gradations is defined as the first image characteristic, and the case where the image data includes two or less gradations is defined as the second image characteristic. However, this is merely an example, and the classification of the first and second image characteristics may be another method.

(Embodiment 2)
In the first embodiment, it is necessary to check all the pixels included in the image data in the image characteristic determination unit 131 shown in FIG. For this reason, the speed until the image data transmitted from the display control unit 12 is processed by the display module 11 and displayed is restricted by the processing in the image characteristic determination unit 131.

  Therefore, in the present embodiment, before transmitting image data from the display control unit 12 to the display module 11, it is determined whether or not the image data includes gradations of three gradations or more, and the attribute information is determined. Assigned to image data. As a result, the display module 11 does not need to check all the pixels included in the image data, and whether to use the left side characteristic or the right side characteristic by simply checking only the attribute information given to the image data. Judgment is possible. Note that the attribute information of the image data may be given at the creation stage of the image data, or may be given by checking the image data at a timing different from the display of the image.

  FIG. 6 is a block diagram of a display device according to this embodiment. Here, in the display device shown in FIG. 6, the same parts as those of the display device shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the following, the description will focus on the parts different from the display device shown in FIG.

  First, in the display control unit 12 according to the present embodiment, an attribute information adding unit 125 is newly provided. The attribute information adding unit 125 acquires the image data from the image data storage unit 122, determines whether or not the image data includes three or more gradation levels, and uses the result as attribute information in the image data. Append. Here, the attribute information is 1-bit information added to each image data. For example, 1 is added as attribute information for image data including gradations of 3 gradations or more, and 0 is added as attribute information for image data including gradations of 2 gradations or less. The attribute information adding unit 125 adds the attribute information to the image data, and then stores the image data to which the attribute information is added in the image data storage unit 126.

  The image data to which the attribute information is added is transmitted to the display module 11 via the drive condition control unit 121. The display drive unit 13 of the display module 11 receives the image data to which the attribute information is added. In the display drive unit 13 according to the present embodiment, an image attribute information determination unit 133 is provided instead of the image characteristic determination unit 131 shown in FIG. The image attribute information determination unit 133 reads the attribute information from the received image data, and determines whether to use the left side characteristic or the right side characteristic based on the attribute information. For example, when the attribute information is 1, the left side characteristic of the voltage-reflectance characteristic of FIG. 3 is used, and when the attribute information is 0, it is determined that the right side characteristic is used.

  Next, FIG. 7 shows a block diagram of the display driving unit 13 according to the present embodiment. FIG. 7 shows that the image attribute information determination unit 133 includes an attribute information analysis unit 23 and a characteristic determination unit 22. The attribute information analysis unit 23 reads the attribute information added to the image data and analyzes the content of the attribute information. The characteristic determination unit 22 is the same as the contents described in the first embodiment except that the characteristic is determined based on the attribute information.

  For example, when the attribute information is 1, the characteristic determination unit 22 according to the present embodiment determines that the image data includes three or more gradations and determines the applied voltage value using the left characteristic. When the attribute information is 0, it is determined that the image data includes gradations of 2 gradations or less, and the applied voltage value is determined using the right side characteristic.

  FIG. 8 is a flowchart showing the operation of the image attribute information determination unit 133 according to this embodiment. The operation of the image attribute information determination unit 133 will be described based on the flowchart shown in FIG. Here, the same steps as those in the flowchart illustrated in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted. In the following, the steps different from FIG. 5 will be mainly described.

  First, the image attribute information determination unit 133 receives image data to which attribute information is added (step AS1). For the image data to which the attribute information is added, the attribute information is read and analyzed by the attribute information analysis unit 23 (step BS1). The characteristic determination unit 22 determines a characteristic for driving the cholesteric liquid crystal display unit 111 based on the result of the analyzed attribute information (step BS2). For example, when the attribute information is 1, it is determined that the image data includes gradations of 3 gradations or more, and the cholesteric liquid crystal display unit 111 is driven using the left side characteristics (step BS3). When the attribute data is 0, it is determined that the image data includes gradations of 2 gradations or less, and the cholesteric liquid crystal display unit 111 is driven using the right side characteristic (step BS4).

  As described above, in the present embodiment, the display control unit 12 determines the gradation of three or more gradations without determining whether or not the display module 11 is image data including the gradation of three or more gradations. Since it is configured to determine whether or not the image data is included and transmit the attribute information to the display module 11, the display module 11 only needs to check the attribute information added to the image data. Processing speed is improved. This makes it possible to quickly perform drive control suitable for the type of image.

(Embodiment 3)
In the first embodiment, the image characteristic determination unit 131 shown in FIG. 2 determines whether to use the left characteristic or the right characteristic for image data, and determines the applied voltage value. And this image characteristic determination part 131 needs to be provided in the display module 11, and the hardware configuration of the display module 11 becomes complicated. Further, the conventional display module 11 cannot be used as it is.

  Therefore, in the present embodiment, in the display control unit 12, it is determined whether the image data uses the left side characteristic or the right side characteristic, and the applied voltage value is determined based on the characteristic. Thereby, it is not necessary to provide the image characteristic determination unit 131 in the display module 11, and the hardware configuration can be simplified. Also, the conventional display module 11 can be used as it is.

  FIG. 9 is a block diagram of a display device according to this embodiment. Here, in the display device shown in FIG. 9, the same parts as those of the display device shown in FIG. Below, it demonstrates centering on a different part from the display apparatus shown in FIG.

  The display control unit 12 illustrated in FIG. 9 includes an image characteristic determination unit 131. Then, the image characteristic determination unit 131 acquires image data from the image data storage unit 122, determines whether the image data includes gradations of three gradations or more, and a characteristic determination unit A characteristic determining unit that determines characteristics to be used for the image data based on the result and determines an applied voltage value is provided. The contents of the characteristic determination unit and the characteristic determination unit are the same as those described in the first embodiment.

  In the display control unit 12 shown in FIG. 9, the applied voltage value is determined by the image characteristic determination unit 131, and the driving condition such as the pulse width of the applied voltage waveform is determined by the driving condition control unit 121. Data on driving conditions such as the determined applied voltage value and pulse width is transmitted to the display module 11. In the display module 11, an applied voltage is supplied based on the data received by the drive unit 132, and the cholesteric liquid crystal display unit 111 is driven.

  The display control unit 12 shown in FIG. 9 can also be configured to add attribute information to image data and determine characteristics based on the attribute information as in the second embodiment. That is, in the display control unit 12, a part for adding attribute information to the image data and a part for determining whether to use the left side characteristic or the right side characteristic based on the attribute information and determining the applied voltage value are added. This is possible.

  As described above, in the present embodiment, since the display control unit 12 includes the characteristic determination unit and the characteristic determination unit, the hardware configuration of the display module 11 can be simplified, and the conventional display module 11 can be used as it is. Can do.

(Embodiment 4)
FIG. 10 is an external view of a large display device according to this embodiment. In FIG. 10, a large display unit 14 is configured by arranging a plurality of display modules 11 in a matrix. In FIG. 10, the large display unit 14 and the display control unit 12 are separated, but the display control unit 12 may be incorporated in the large display unit 14.

  In Embodiment 1 or the like, an example of a display device that analyzes gradation information of an image to be displayed and determines whether to use the left side characteristic or the right side characteristic of the voltage-reflectance characteristic based on the result is shown. Even in the case of a large display device, as shown in FIG. 11, depending on an image to be displayed, an image region 15 (an image such as a photograph that needs to express a halftone) to be controlled using the left side characteristic and a right side characteristic are used. It is conceivable that image areas 16 (illustrations, characters, etc.) to be controlled are mixed.

  In such a case, the large display device is driven by analyzing the gradation information of the image data displayed for each display module 11 and determining whether the left side characteristic or the right side characteristic is used for each display module 11. It is possible. As a result, it is possible to simultaneously drive a full color display portion including three or more gradations and a portion including two or less gradations in one image with optimum characteristics. The expression effect can be enhanced.

  FIG. 12 is a block diagram of a large display device according to this embodiment. In the block diagram shown in FIG. 12, the same parts as those in the block diagram shown in FIG. The large display unit 14 shown in FIG. 12 is configured by arranging a plurality of display modules 11 in a matrix. The display modules 11 are arranged close to each other so that the seam is not conspicuous in a tile shape.

  On each display module 11, a part of the image divided in accordance with the size of the display module 11 is displayed, and one image is displayed on the entire large display unit 14. Unlike the display control unit 12 shown in FIG. 2, the display control unit 12 according to the present embodiment differs from the display control unit 12 in that it includes an image data dividing unit 127 that divides a partial image corresponding to the size of each display module 11, and divided image data. Is added to the image data storage unit 128.

  Furthermore, a display module control unit 123 that performs synchronous control on the display of each display module 11 is added to the display control unit 12 according to the present embodiment. The display module control unit 123 transmits an image, a driving condition, a synchronization timing, and the like divided according to the size of each display module 11 to all the display modules 11, and the large display unit 14 has one display module 11. An image can be displayed.

  Next, the operation of the display control unit 12 according to the present embodiment will be described. The image data dividing unit 127 receives the image data of the image data storage unit 122 and divides the image data corresponding to the size of each display module 11. The divided image data is temporarily stored in the image data storage unit 128.

  The drive condition control unit 121 reads the divided image data from the image data storage unit 128, and determines a drive condition of the cholesteric liquid crystal for each divided image data. In addition, the drive condition control unit 121 transmits the divided image data, the drive condition, and the like to the display module control unit 123 at the same time. The display module control unit 123 sequentially transmits the divided image data, driving conditions, and the like to each display module 11. At that time, necessary synchronization signals are also transmitted so that all the display modules 11 can simultaneously display images.

  Note that the large-sized display device according to this embodiment can be formed by arranging the display devices described in Embodiment 1 in a matrix. However, it is necessary to add a display module control unit 123 that controls each display module 11 to the display control unit 12 according to the present embodiment.

  FIG. 13 is a flowchart showing the operation of the large display device according to the present embodiment. First, the image characteristic determination unit 131 of each display module 11 receives the divided image data (step CS1). The image characteristic determination unit 131 of the display module 11 analyzes the gradation information of all the pixels with respect to the divided image data (step CS2). Based on the analysis result of step CS2, it is determined whether or not the divided image data includes gradations of 3 gradations or more (step CS3). When the number of gradations including three or more gradations is included, it is determined that the cholesteric liquid crystal display unit 111 is driven using the left side characteristics (step CS4). It is determined that the cholesteric liquid crystal display unit 111 is driven by using (step CS5).

  The display module control unit 123 determines whether to use the left-side characteristic or the right-side characteristic of the voltage-reflectance characteristic for all the display modules 11 constituting the large-sized display unit 14, and all the determinations are completed. It is confirmed whether or not (step CS6). When there is a display module 11 that has not been determined in step CS3, the processing from step CS2 to step CS5 is performed on the display module 11. When the determination of all the display modules 11 is completed, the image characteristic determination unit 131 of each display module 11 determines the applied voltage value of the cholesteric liquid crystal display unit 111 based on the selected characteristic (step AS6), and the driving unit 132. (Step AS7).

  As described above, in this embodiment, since the display module 11 described in Embodiment 1 is arranged in a matrix to form a large display device, a full color image portion such as a photograph has a voltage-reflectance characteristic. By driving with the left-hand side characteristics, it is possible to express a lot of colors, and the parts such as illustrations and letters are better than driving with the left-side characteristics by driving with the right-side characteristics of the voltage-reflectance characteristics. Contrast can be obtained. By mixing the display module 11 driven using the left side characteristics and the display module 11 driven using the right side characteristics, a large display device capable of displaying most suitable for an image can be configured.

(Embodiment 5)
In the large display device according to the fourth embodiment, it is necessary to check the gradation of all the pixels of the divided image data for each display module 11. Therefore, the speed until the image data transmitted from the display control unit 12 is processed and displayed by each display module 11 is restricted by the processing by the image characteristic determination unit 131 of each display module 11. .

  Therefore, in the present embodiment, before the divided image data is transmitted to each display module 11, it is determined whether or not the divided image data includes three or more gradations, and the attribute is determined. Information is assigned to each divided image data. Thereby, each display module 11 does not need to check all the pixels of the divided image data, and only the attribute information given to the divided image data is checked, so that either the left characteristic or the right characteristic can be obtained. It is possible to determine whether to use. Note that the attribute information of the image data may be given at the creation stage of the image data, or may be given by checking the image data at a timing different from the display of the image.

  FIG. 14 is a block diagram of a large display device according to this embodiment. In the large display device shown in FIG. 14, the same parts as those in the large display device shown in FIG. In the following description, the description will focus on parts different from FIG.

  The image data divided by the image data dividing unit 127 is transmitted to the attribute information adding unit 125. The attribute information adding unit 125 adds, for each divided image data, attribute information indicating whether or not the divided image data includes three or more gray levels. For example, 1 is added as attribute information for divided image data including gradations of 3 gradations or more, and 0 is added as attribute information for divided image data including gradations of 2 gradations or less. . After the processing by the attribute information adding unit 125, the image data to which the attribute information is added is stored in the image data storage unit 129.

  In the present embodiment, an image attribute information determination unit 133 shown in FIG. 14 is provided instead of the image characteristic determination unit 131 shown in FIG. The image attribute information determination unit 133 receives the image data to which the attribute information is added, reads out the attribute information, and performs analysis. For example, when the attribute information is 1, the image attribute information determination unit 133 determines that the cholesteric liquid crystal display unit 111 is driven using the left side characteristic of the voltage-reflectance characteristic, and when the attribute information is 0, the voltage information -It determines with driving the cholesteric liquid crystal display part 111 using the right side characteristic of a reflectance characteristic.

  The large display device according to the present embodiment can be configured by arranging the display devices described in the second embodiment (display devices to which attribute information is added in the display control unit 12) in a matrix. It is. However, it is necessary to add a display module control unit 123 that controls each display module 11 to the display control unit 12 according to the present embodiment.

  FIG. 15 is a flowchart showing the operation of the large display device according to the present embodiment. First, the image attribute information determination unit 133 of each display module 11 receives the divided image data (step CS1). The image attribute information determination unit 133 reads and analyzes the attribute information from the divided image data transmitted by the display module control unit 123 (step DS1). Then, the image attribute information determination unit 133 determines characteristics for driving the cholesteric liquid crystal display unit 111 based on the attribute information (step DS2).

  For example, when the attribute information is 1, it is determined that the image data includes three or more gradations, and it is determined to drive the display module 11 using the left side characteristics (step DS3). If the attribute data is 0, it is determined that the image data includes gradations of 2 gradations or less, and it is determined that the display module 11 is driven using the right side characteristics (step DS4).

  The display module control unit 123 determines whether to use the left-side characteristic or the right-side characteristic of the voltage-reflectance characteristic for all the display modules 11 constituting the large-sized display unit 14, and all the determinations are completed. It is confirmed whether or not (step CS6). When the determination of all the display modules 11 is completed, the image characteristic determination unit 131 of each display module 11 determines the applied voltage value of the cholesteric liquid crystal display unit 111 based on the selected characteristic (step AS6), and the driving unit 132. (Step AS7).

  As described above, in the present embodiment, the display module 11 described in the second embodiment is arranged in a matrix to constitute a large display device. Therefore, either the left side characteristic or the right side characteristic of the voltage-reflectance characteristic is obtained. When determining whether to use, it is only necessary to check the attribute information, and the display processing speed can be improved. This makes it possible to quickly perform drive control suitable for the type of image. Further, in the present embodiment, the display module 11 using the left characteristic and the display module 11 using the right characteristic are driven in a mixed manner, so that the display most suitable for the image can be performed.

(Embodiment 6)
In the fourth embodiment, each display module 11 includes an image characteristic determination unit 131 that analyzes the gradation of image data and determines characteristics. Therefore, the same number of image characteristic determination units 131 as the number of display modules 11 are required. In addition, since the display module 11 must always include the image characteristic determination unit 131, the conventional display module 11 cannot be simply used.

  Therefore, the large display device according to the present embodiment is configured to include the image characteristic determination unit 131 in the display control unit 12. Accordingly, it is not necessary to provide the image characteristic determination unit 131 in each display module 11, the hardware configuration can be reduced, and the processing in the display module 11 can be simplified. The large display device according to this embodiment can be configured by arranging the display device of Embodiment 3 in a matrix.

  FIG. 16 is a block diagram of a large display device according to this embodiment. Below, it demonstrates centering on a different part from the block diagram shown in FIG. First, the display control unit 12 according to the present embodiment is provided with an all display module image characteristic determination unit 124. The all-display module image characteristic determination unit 124 reads the divided image data, analyzes the gradation of all pixels for each divided image, and uses either the left characteristic or the right characteristic of the voltage-reflectance characteristic. Judging whether to do.

  The drive unit 132 of each display module 11 drives the cholesteric liquid crystal display unit 111 based on the result of the all display module image characteristic determination unit 124 and the drive condition of the drive condition control unit 123.

  In addition, the display control unit 12 according to the present embodiment can be configured to add attribute information to the divided image data as in the fifth embodiment and determine the characteristics based on the attribute information. It is. That is, in the display control unit 12, a part for adding attribute information to the image data and a part for determining whether to use the left side characteristic or the right side characteristic based on the attribute information and determining the applied voltage value are added. This is possible.

  As described above, in the present embodiment, the display modules 11 described in the third embodiment are arranged in a matrix to form a large display device. Therefore, each display module 11 has a left-side characteristic or a voltage-reflectance characteristic. It is not necessary to provide a part for determining which of the right side characteristics is used for driving, the hardware configuration can be reduced, and the processing in the display module 11 is simplified. In the present embodiment, the conventional display module 11 can be used as it is.

It is the schematic of the display apparatus which concerns on Embodiment 1 of this invention. 1 is a block diagram of a display device according to Embodiment 1 of the present invention. It is a figure which shows the relationship of the voltage-reflectance characteristic of a cholesteric liquid crystal. It is a block diagram of the display drive part concerning Embodiment 1 of the present invention. It is a flowchart of the display apparatus which concerns on Embodiment 1 of this invention. It is a block diagram of the display apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the display drive part which concerns on Embodiment 2 of this invention. It is a flowchart of the display apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the display apparatus which concerns on Embodiment 3 of this invention. It is the schematic of the display apparatus which concerns on Embodiment 4 of this invention. It is the schematic of the display apparatus which concerns on Embodiment 4 of this invention. It is a block diagram of the display apparatus which concerns on Embodiment 4 of this invention. It is a flowchart of the display apparatus which concerns on Embodiment 4 of this invention. It is a block diagram of the display apparatus which concerns on Embodiment 5 of this invention. It is a flowchart of the display apparatus which concerns on Embodiment 5 of this invention. It is a block diagram of the display apparatus which concerns on Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Display module, 111 Cholesteric liquid crystal display part, 12 Display control part, 121 Drive condition control part, 122,126,128,129 Image data storage part, 123 Display module control part, 124 All display module image characteristic determination part, 125 attributes Information adding unit, 127 Image data dividing unit, 13 Display driving unit, 131 Image characteristic determining unit, 132 Driving unit, 14 Large display unit.

Claims (8)

A display device using cholesteric liquid crystal;
A characteristic determination unit that determines whether the image data to be displayed on the display device is a first image characteristic or a second image characteristic;
When the characteristic determining unit determines that the image data is the first image characteristic, the driving condition of the display device is determined using the first characteristic of the cholesteric liquid crystal, and the second image characteristic is determined. And a characteristic determining unit that determines a driving condition of the display device using a second characteristic of the cholesteric liquid crystal. The display device according to claim 1,
The first image characteristic is characterized in that the image data includes three or more gradations, and the second image characteristic includes the image data including two or less gradations. Display device. The display device according to claim 1 or 2,
A display module and a display control unit for controlling the display module;
The display device, wherein the display device, the characteristic determination unit, and the characteristic determination unit are provided in the display module. The display device according to claim 1 or 2,
A display module and a display control unit for controlling the display module;
The characteristic determination unit is provided in the display control unit,
The display device and the characteristic determination unit are provided in the display module,
Furthermore, the display control unit includes an attribute addition unit that adds attribute information indicating a determination result of the characteristic determination unit to the image data. The display device according to claim 1 or 2,
A display module and a display control unit for controlling the display module;
The characteristic determination unit and the characteristic determination unit are provided in the display control unit,
The display device, wherein the display device is provided in the display module. A large-sized display device using the display device according to claim 1 or 2,
A plurality of display modules and a display control unit for controlling the plurality of display modules;
The large-sized display device, wherein the display device, the characteristic determination unit, and the characteristic determination unit are provided in each of the plurality of display modules. A large-sized display device using the display device according to claim 1 or 2,
A plurality of display modules and a display control unit for controlling the plurality of display modules;
The characteristic determination unit is provided in the display control unit,
The display device and the characteristic determination unit are provided in the plurality of display modules,
Furthermore, the display control unit includes an attribute addition unit that adds attribute information indicating the determination result of the characteristic determination unit to the image data. A large-sized display device using the display device according to claim 1 or 2,
A plurality of display modules and a display control unit for controlling the plurality of display modules;
The characteristic determination unit and the characteristic determination unit are provided in the display control unit,
The large display device, wherein the display device is provided in each of the plurality of display modules.

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