JP2005092034A - Liquid crystal display device and display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent tone reversal in which colors are seen as if they are changed depending on angles by which a user observes a display screen. <P>SOLUTION: This liquid crystal display is equipped with a means 2 for receiving input of a visual inspection direction of the user to the display screen of the liquid crystal display 1 from the outside, a means 3 for converting original image data created on the premise that the user performs visual inspection of the display screen from the front into data so that no tone reversal occurs corresponding to the inputted visual inspection direction and a means 4 for performing picture display by using the image data after conversion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a display method using liquid crystal, and more specifically, image data is corrected in order to prevent tone reversal so that displayed colors look different depending on the angle at which the liquid crystal display screen is viewed. The present invention relates to a liquid crystal display device and a display method.

  In a liquid crystal display device widely used as a data display device for images and the like, it is well known that the screen becomes difficult to see depending on the angle at which the user views the display screen. When the display screen is viewed obliquely as compared to when viewed from the front, the display screen is generally difficult to see. For example, in a display device using TFT liquid crystal, when viewed from an obliquely upward direction of the display screen, the color may be different from that viewed from the front, that is, gradation inversion may occur.

  The direction of gradation inversion when viewed from different directions depends on the liquid crystal manufacturing method and its mounting method, but in many liquid crystal display devices, gradation inversion occurs when viewed from diagonally upward or downward. It has been known.

  FIG. 12 shows a configuration example of a liquid crystal display system as a conventional screen data display device. In the figure, it is assumed that a personal computer 50 and a liquid crystal display device 51 are connected, and the liquid crystal display device 51 is connected to a programmable logic controller (PLC) 52 used for control in a factory or the like. Then, the screen data created by the screen data creation tool 54 on the personal computer 50 side is temporarily stored in the file 55, for example, and then transferred to the display device 51 and used for displaying various control data of the PLC 52, for example.

  As shown in FIG. 12, for example, when the liquid crystal display device is used for displaying various control data of the PLC 52, the display device 51 is mounted at various positions near, for example, a control panel or various machines. Will be used.

  Therefore, the position (height, etc.) and the direction of the display screen also vary, and the screen data created by using the screen data creation tool 54 on the personal computer 50 side, that is, the screen originally created on the assumption that it is viewed from the front. When data is displayed on the display device 51 side, for example, depending on the angle at which the operator views the display screen, a color different from the color that should be originally displayed can be seen due to a change in luminance gradation, that is, gradation can be reversed. Sex exists. In order to prevent such tone reversal, a liquid crystal display device using a wide viewing angle film is also used. However, in this case, there is a problem that the cost increases.

The following documents are available as conventional techniques for solving such problems related to the viewing direction (viewing angle) of the liquid crystal.
Japanese Patent Laid-Open No. 7-294872 “Liquid Crystal Display Panel” JP 2003-14924 A (P2003-14924A) “Optical Anisotropic Element Manufacturing Method and Optical Anisotropic Element” Patent Document 1 automatically detects a viewing angle by scanning a distance sensor by rotating an arm. Although a technology for setting the drive voltage level applied to each pixel of the liquid crystal display panel according to the viewing angle is disclosed, a special mechanism is required for automatic detection of the viewing angle, and the control is complicated. There was a problem of becoming.

  Patent Document 2 discloses an optical anisotropic element that is manufactured by further irradiating ultraviolet light onto an element having a phase difference caused by polarized light exposure, and can obtain the effect of expanding the field of view of a liquid crystal display device. Adoption of special elements also has problems from the viewpoint of cost.

  An object of the present invention is to change the color, that is, to invert the gradation, by correcting the screen data by a simple data conversion process and displaying the screen by a simple data conversion process corresponding to the viewing angle of the liquid crystal display screen without increasing the cost. It is to provide a liquid crystal display device and a display method capable of reducing the above, and to improve the display performance of the liquid crystal display device.

FIG. 1 is a block diagram showing the principle configuration of the liquid crystal display device of the present invention. In FIG. 1, the liquid crystal display device 1 includes a viewing direction input unit 2, an image data conversion unit 3, and a display unit 4.
The viewing direction input unit 2 receives an input of the user's viewing direction with respect to the display screen of the liquid crystal display device 1 from the outside, and the image data conversion unit 3 is created on the assumption that the user views the display screen from the front. The original image data thus converted is converted into data corresponding to the input viewing direction, and the display means 4 performs screen display using the converted image data.

  In the embodiment of the invention, as the conversion to the data corresponding to the viewing direction by the image data conversion means 3, the original image data is reduced so as to reduce the gradation inversion compared to when the original image data is viewed from the front. Can also be converted.

  In this case, the image data conversion means 3 can also convert the original image data based on a conversion curve that gives a relationship between the original image data and the data corresponding to the viewing direction, and further in the inputted viewing direction. Correspondingly, one of a plurality of conversion curves can be selected, and the original image data can be converted based on the selected conversion curve.

  Next, with respect to the display method of the present invention, the input of the user's viewing direction with respect to the display screen of the liquid crystal display device is received from the outside, and the original image data created on the assumption that the user views the display screen from the front, A method of converting the data into data corresponding to the input viewing direction and performing screen display using the converted image data is used.

  In the embodiment of the invention, a program used by a computer to realize this display method and a computer-readable portable storage medium storing the program used by the computer can be used.

  According to the present invention, it is possible for the user to recognize the correct color even when the angle at which the user views the display screen of the liquid crystal display device is changed. Depending on the position of the liquid crystal display device, the angle of the display screen, etc., prepare multiple data conversion curves according to several angles, and select one of them to correct gradation inversion By performing the above, it is possible to display appropriate data corresponding to the angle, which greatly contributes to improving the practicality of the liquid crystal display device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a configuration example of the liquid crystal display system in the present embodiment. This figure is basically similar to the configuration of the conventional example of FIG. 12, but the liquid crystal display device is connected to a programmable logic controller (PLC) to display various control data and characteristics. For emphasis, the programmable display 10 is named, and the programmable display 10 is connected to the personal computer 11 and the PLC 12. In the personal computer 11, a screen creation tool 13 is provided as in FIG.

  The programmable display 10 is connected to a CPU 15 for controlling the whole, an LCD 16 as a display element, an LCD controller 17 as its controller, a video memory 18 for storing image data to be displayed on the LCD 16, a personal computer 11 and a PLC 12, and the like. An external input / output port 19, a flash memory 20, a RAM memory 21 for storing work data, and a touch panel 22 are provided.

FIG. 3 is an explanatory diagram of screen data conversion and display corresponding to the angle at which the user views the display screen when displaying the control data of the PLC 12 on the LCD 16.
Similarly to FIG. 12 of the conventional example, the screen data created by the screen creation tool 13 in the personal computer 11 of FIG. 2 is stored as screen data 25 in the flash memory 20 in FIG. For example, when an angle for viewing the display screen is input from the user via the touch panel 22, the CPU 15 performs data conversion on the screen data 25 stored in the flash memory 20, and the converted data is expanded and temporarily stored in, for example, the video memory 18. The stored data and the converted data are read from the video memory 18 and displayed on the LCD 16 by the LCD controller 17. 2 and 3, instead of providing the LCD controller 17, the CPU 15 can perform the operation instead. In this case, the RAM memory 21 or the like is used instead of the video memory 18.

  Here, the influence of the viewing direction in the liquid crystal display element, for example, TFT liquid crystal, that is, the direction in which the user views the display screen will be described with reference to FIGS. FIG. 4 is an explanatory diagram of the relationship between the liquid crystal display result, for example, the luminance as a result of using the backlight, and the size of the input data corresponding to the pixels of the liquid crystal. Here, the influence of the viewing direction will be described on the assumption that the input image data has 5 bits, that is, 32 levels from 0 to 31, and the luminance also has 32 gradations from 0 to 31.

  When viewed from the front, for the sake of simplicity, it is assumed that the luminance is proportional to the value of the input data and increases linearly with respect to the value of the input data. On the other hand, when viewed from obliquely upward, the attenuation is particularly large when the value of the input data is small, and the luminance tends to increase rapidly when the value of the input data exceeds a certain value. Further, the curve swells downward as the angle θ between the normal direction of the display screen and the viewing direction increases. When viewed from an obliquely downward direction, the shape of the curve is opposite to that observed from an obliquely upward direction, and is a curve that swells upward, that is, the luminance is saturated within a large range of input data.

  The curves in FIG. 4 are almost the same for the three primary colors R, G, and B. As described above, the influence of the viewing direction varies depending on the manufacturing method and the mounting method of the liquid crystal element. However, here, the gradation correction method of the present invention will be further described by taking a liquid crystal having the characteristics shown in FIG. 4 as an example.

  FIG. 5 is an example of a numerical display (table) of the data conversion curve corresponding to the characteristics of FIG. In the same figure, when the converted data is calculated by the following equation using the image data created on the assumption that the display screen is viewed from the front as the input value and the value of γ as the variable corresponding to the viewing angle. Are shown in the table as correction values. Note that “31” in this equation is the maximum value of the input data, and is generally a constant determined by the luminance gradation of the display.

The actual conversion of the input image data may be calculated using the above equation, or the correction value may be obtained using the table of FIG.
In FIG. 5, the value of γ is a value corresponding to the viewing direction of the screen by the user as described above. For example, the value is 0.25 for oblique downward correction (large). This is used to correct the luminance characteristics when the angle θ on the right in FIG. 4 is large. For example, the value of γ in the case of diagonally upward correction (small) is 2, which is used to correct the luminance characteristic when the central angle θ in FIG. 4 is relatively small.

  FIG. 6 illustrates the conversion characteristics of FIG. In the same figure, the straight line without correction corresponds to the luminance characteristic when viewed from the left front of FIG. 4, and the input data is output as it is without being substantially corrected. On the other hand, the two curves corresponding to the upward correction correspond to the center diagram of FIG. 4, and the conversion curve has a shape that swells upward in order to perform correction to increase the value in a small range of input data. Further, as the angle θ between the direction in which the user views the screen and the normal direction of the screen increases, the bulge becomes larger.

On the other hand, the two correction curves for the diagonally downward direction correspond to the diagram on the right side of FIG. 4, and are correction curves that swell downward to avoid saturation when the input data is large.
FIG. 7 is an explanatory diagram of a specific example of such color correction, that is, image data conversion. In the figure, the upper center is image data for a certain pixel before conversion corresponding to when viewed from the front, and since the values of R and G are both 31, the display color is yellow. The lower center data is also pre-conversion image data corresponding to a case where another pixel is viewed from the front, but since the R value is 31 and the G value is 15, there is a slight change in color. When viewed from the front, the display color is basically yellow.

  On the other hand, the left side corresponds to the display when viewed obliquely upward, and shows equivalent image data corresponding to the luminance of the display result. In the upper data, the value of G is slightly decreased to 29. As a display color, yellow can be visually recognized. On the other hand, for the lower data, the value of G attenuates from 15 to 3, for example, so that the display when viewed from the front is yellow, while viewed from obliquely upward. In this case, the display color will appear red.

  The right-side converted data naturally does not change with respect to the upper data, but with respect to the lower data, the G value is corrected from 15 to 25 to correct the attenuation when viewed obliquely from above. Even when attenuation is taken into consideration, the display can be visually recognized as yellow even when viewed obliquely from above.

  FIG. 8 is an overall flowchart of image data correction display processing according to this embodiment. When the processing is started in the figure, first, in step S1, designation of the viewing direction, that is, the angle θ formed by the normal direction of the display screen and the viewing direction, for example, corresponding to the position and state where the display device is attached. User input is received.

  Subsequently, an image data conversion curve corresponding to the angle θ specified in step S2 is selected from the plurality of conversion curves described with reference to FIG. 6, and R, G, B image data ( Display image data is generated based on the conversion curve) and the converted image, and the converted image is displayed in step S4, and the process ends.

  In the above description, the embodiment has been described on the assumption that data conversion is performed for each of R, G, and B image data corresponding to each pixel on the display screen. However, the image data corresponding to each pixel is directly converted. A case where palette data corresponding to each pixel is converted instead of conversion will be described as a different embodiment with reference to FIGS.

  FIG. 9 is an explanatory diagram of a palette data table. This table stores image data of colors that can be displayed corresponding to each pixel on the display screen of the liquid crystal display device. For example, when 128 colors can be displayed, data corresponding to R, G, and B is stored for color numbers 0 to 127, respectively. For example, for color number 0, the values of R, G, B are all 0. In this case, black is displayed, and for color number 113, the values of R, G, B are both 15, Is displayed in gray, and for the color number 127, the values of R, G, and B are all 31, so that white is displayed.

  FIG. 10 shows an example of the contents stored in the pixel data memory corresponding to the palette data table. In the pixel data memory, the color to be displayed is given as the color number of the palette data table corresponding to each of the m × n pixels on the display screen. Thus, an arbitrary screen display can be performed by specifying the color number for each pixel using the contents of the palette data table.

  In a different embodiment, the contents stored in the palette data table, that is, the values of R, G, and B corresponding to the color numbers, are shown in the conversion curve of FIG. 6 corresponding to the direction (angle θ) the user views the display screen. By performing conversion using either one, the color correction processing corresponding to the display screen is performed without changing the contents of the image data memory in FIG.

  Although the details of the liquid crystal display device and the display method of the present invention have been described above, the liquid crystal display device can naturally be used by being included in a general computer system. FIG. 11 is a block diagram showing the configuration of such a computer system, that is, a hardware environment.

  In FIG. 11, the computer system includes a central processing unit (CPU) 30, a read only memory (ROM) 31, a random access memory (RAM) 32, a communication interface 33, a storage device 34, an input / output device 35 including a liquid crystal display device, a portable type. A storage medium reading device 36 and a bus 37 to which all of them are connected are configured.

  As the storage device 34, various types of storage devices such as a hard disk and a magnetic disk can be used, and the program shown in the flowchart of FIG. The program according to claim 6 in the range is stored, and such a program is executed by the CPU 30, so that it is possible to prevent gradation inversion by converting image data according to the viewing direction of the user in the present embodiment. .

  Such a program is stored, for example, in the storage device 34 from the program provider 38 via the network 39 and the communication interface 33, or in a portable storage medium 40 that is commercially available and distributed. It can also be set in the reading device 36 and executed by the CPU 30. As the portable storage medium 40, various types of storage media such as CD-ROM, flexible disk, optical disk, magneto-optical disk, and DVD can be used, and the program stored in such a storage medium is read by the reading device 36. By reading the image data, it is possible to perform image data correction processing corresponding to the angle at which the user views the liquid crystal display screen in the present embodiment.

  In the above, for example, image data is created on the premise that the user views the display screen from the front on the personal computer side, and the image data is converted on the display device side according to the viewing direction of the user. Naturally, it is possible to take various embodiments such as creating image data in advance using the viewing direction (angle) as a parameter on the personal computer side and performing display using the data on the display device side. 2 and 3, image data corresponding to the viewing direction of the user can be created on the personal computer 11 side, and the image data can be stored in the video memory 18 and displayed on the programmable display 10 side. is there.

  Further, in the above description, the embodiment has been described in which the change in the viewing direction of the user with respect to the display screen is (diagonal) in the vertical direction, but the present invention is naturally applicable to the case where the change in direction is in the horizontal direction.

  The present invention can be used in any industry that uses liquid crystal display elements as a matter of course in the manufacturing industry of liquid crystal display devices.

It is a principle block diagram of the liquid crystal display device of the present invention. It is a block diagram of the structural example of a liquid crystal display system. It is explanatory drawing of the conversion operation | movement of the image data in FIG. It is explanatory drawing of the influence of the visual recognition direction with respect to the relationship between a brightness | luminance and input data. It is an example of the numerical display of the conversion characteristic of input data. It is an example of the conversion characteristic curve of image data. It is explanatory drawing of the specific example of image data conversion. It is a whole flowchart of an image data correction display process. It is explanatory drawing of a pallet data table. It is an example of the storage content of the pixel data memory corresponding to a palette data table. It is a figure explaining the loading to the computer of the program in this invention. It is a block diagram which shows the structure of the prior art example of a liquid crystal display system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51 Liquid crystal display device 2 Visual direction input means 3 Image data conversion means 4 Display means 10 Programmable display 11,50 Personal computer 12,52 Programmable logic controller (PLC)
13 Screen creation tool 15,30 CPU
16 LCD
17 LCD controller 18 Video memory 19 External input / output port 20 Flash memory 21 RAM memory 22 Touch panel 25 Screen data 31 Read only memory (ROM)
32 Random access memory (RAM)
33 Communication Interface 34 Storage Device 35 Input / Output Device 36 Reading Device 37 Bus 38 Program Provider 39 Network 40 Portable Storage Medium 54 Screen Data Creation Tool 55 File

Claims (7)

In a display device using liquid crystal,
Visual direction input means for receiving an input of a user's visual direction on the display screen of the device from the outside;
Image data conversion means for converting original image data created on the premise that the user visually recognizes the display screen from the front, to data corresponding to the input viewing direction;
A liquid crystal display device comprising: display means for performing screen display using the converted image data.   As the conversion to the data corresponding to the viewing direction, the image data conversion means converts the original image data so that no color change occurs compared to when the original image data is viewed from the front. The liquid crystal display device according to claim 1.   2. The liquid crystal display according to claim 1, wherein the image data converting means converts the original image data based on a conversion curve that gives a relationship between the original image data and data corresponding to the viewing direction. apparatus.   The image data conversion means selects one of the plurality of conversion curves corresponding to the input viewing direction, and performs conversion of original image data based on the selected conversion curve. The liquid crystal display device according to claim 3. In a display method using a liquid crystal display device,
Receiving an external input of the user's viewing direction on the display screen of the device,
The original image data created on the premise that the user visually recognizes the display screen from the front is converted into data corresponding to the input viewing direction,
A display method characterized by performing screen display using the converted image data. In a program used by a computer equipped with a liquid crystal display device,
A procedure for receiving an external input of the user's viewing direction on the display screen of the device;
A procedure for converting original image data created on the assumption that the user visually recognizes the display screen from the front, to data corresponding to the input viewing direction;
A program for causing a computer to execute a screen display procedure using the converted image data. In a storage medium used by a computer comprising a liquid crystal display device,
Receiving from the outside an input of a user's viewing direction on the display screen of the device;
Converting the original image data created on the assumption that the user visually recognizes the display screen from the front to data corresponding to the input viewing direction;
A computer-readable portable storage medium storing a program for causing a computer to execute a screen display step using the converted image data.

Images