JP2007147956A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of improving convenience to a viewer by allowing an image to be viewed, even if a fault occurs in a light source that emits light ray in some color in the display device, using an illumination device which has a plurality of kinds of light sources that emit illumination light of different colors. <P>SOLUTION: The display device includes the illumination device, having a plurality of first and second light sources 11 and 10 emitting illumination lights that differ in color and a display panel 3 for displaying an image, by modulating the illumination lights of the illumination device, on the basis of an input video signal. When a fault has occurred in a second light source 10, all the second light sources 10 are extinguished, and at least the first light sources 11 are lit. Accordingly, the viewer can continue to view the image with less in-congruities. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device that includes a plurality of light sources having different colors and includes an illumination device that illuminates a light modulation panel from its back surface.

  In recent years, in a non-self-luminous display device using a light modulation panel such as a liquid crystal panel, a fluorescent tube (hereinafter referred to as a fluorescent lamp, CCFL) used as a light source of an illuminating device (backlight device) as the screen size increases. , Which is also referred to as a cold cathode tube), and the number of fluorescent tubes is increasing. As the number of fluorescent tubes increases, measures to be taken when one of the plurality of fluorescent tubes is not lit become a problem.

  In a backlight device using only a plurality of fluorescent tubes emitting white light, the lamp protection circuit informs the microcomputer when at least one of the plurality of fluorescent tubes is not lit. Therefore, it is common to turn off the power of the product, and viewing cannot be performed even if one fluorescent tube is not lit.

  As an improvement plan of this problem, in Japanese Patent Application Laid-Open No. 2004-53988, even if one fluorescent tube is not lit, without forcibly turning off the fluorescent tube driving circuit, Proposals have been made to enable the user to continue viewing with peace of mind by performing a non-lighting process only at the failure location.

  In a backlight device using only a plurality of white fluorescent tubes, even if one of the plurality of fluorescent tubes is not lit, the brightness of the entire display screen is only slightly uneven, Since there is no change in the color component of the light device itself, the color tone of the displayed image does not change. For this reason, even if one fluorescent tube is turned off, the viewer feels less uncomfortable and the above-described measures are possible.

  In recent years, products that employ not only fluorescent tubes but also light emitting diodes (hereinafter referred to as LEDs) have appeared as light sources for backlight devices. The purpose of adopting the LED is mainly to enlarge the color reproduction range. Specific to a backlight device using three types of LEDs that emit three primary colors of red, green, and blue, and a conventional fluorescent tube that emits white light in order to achieve both cost and color reproducibility expansion. Backlight devices using various light sources such as those using a combination of LEDs emitting a single color have been developed.

  For example, according to a backlight device comprising a combination of a fluorescent tube that emits white light and an LED that emits red light, it becomes possible to compensate for the portion of the white fluorescent tube where the amount of red wavelength light is insufficient by the light emission of the red LED. In particular, the red color reproduction range can be expanded.

  In such a backlight device using a plurality of types of light sources that emit different colors, when a light source that emits a certain color is not lit, some of the plurality of white fluorescent tubes are not lit. Unlike the case of the above, the color tone of the entire backlight device changes greatly, and the displayed video also has an unnatural color tone.

  For example, in the above-described backlight device using a combination of a white fluorescent tube and a red LED, when the red LED is turned off, the color of the display image is composed of blue, green, and cyan, yellow is green, and magenta is It becomes blue and the video becomes uncomfortable for the viewer.

  In addition, even on-screen displays such as menus (hereinafter referred to as OSD displays), characters that are not displayed are generated due to the above-described change in color tone. For example, when a backlight device using a combination of a white fluorescent tube and a red LED is used, the OSD display of a red character for warning becomes unclear due to extinction of the red LED, which causes a problem in product use.

In order to prevent these problems, in a backlight device having a plurality of light sources of different colors, when a light source that emits a certain color is not lit due to a malfunction, light sources that emit other colors can be turned on. However, it is common to turn off all light sources of the backlight device.
JP 2004-53988 A

  However, if a backlight device malfunction occurs, if the specifications that immediately turn off all the light are used, which part of the product is defective, and if it is estimated that the backlight device is defective, in which part of the backlight device It will be in the state which does not understand whether there is a malfunction.

  For this reason, the user cannot know the extent of the problem, cannot give a specific explanation to the service, and a problem arises that the response of the service is delayed. Since the backlight device itself controls lighting of a plurality of light sources, the contents of the trouble are complicated, and the importance of knowing the contents of the trouble more specifically when the trouble occurs is increasing.

  Further, even when a plurality of light sources that emit different colors are used, the light sources are not in a completely complementary relationship, and the light emission wavelengths may overlap somewhat. At that time, even when illumination light of only a certain light source is used, it may be considered that viewing is possible to some extent. Therefore, it is desirable to maintain a viewable state to some extent when the backlight device is defective.

  Here, if only the defective light source is turned off, color unevenness and brightness unevenness occur on the screen, which gives viewers discomfort. Furthermore, when the light source that emits a certain color is turned off, the color component of the illumination light (backlight) changes, the color tone of the display image changes, and the OSD display such as the menu becomes unclear. There's a problem.

  The present invention has been made to solve the above-described problems, and in a display device using an illuminating device having a plurality of types of light sources that emit different colors, a problem occurs in the light source that emits a certain color. Even in this case, it is possible to provide a display device that enables viewing of an image and can improve the convenience of the viewer.

  According to a first aspect of the present application, there is provided an illuminating device having a plurality of first and second light sources that emit different colors, and image display by modulating illumination light of the illuminating device based on an input video signal. In a display device comprising display means for performing, when the luminance control for the second light source becomes impossible, all of the second light source is turned off and at least the first light source is turned on. And

  According to a second aspect of the present invention, an illuminating device having a plurality of first and second light sources that emit different colors, and image display by modulating the illuminating light of the illuminating device based on an input video signal. In a display device comprising display means, when at least a part of the second light source is not lit, all of the second light source is turned off and at least the first light source is turned on. Features.

  A third invention of the present application is characterized in that, in the display device of the first or second invention, the user is notified that all of the second light source is turned off.

  A fourth invention of the present application is characterized in that, in the display device of the third invention, the display means displays on-screen that all of the second light source is turned off.

  According to a fifth aspect of the present invention, in the display device according to any one of the first to fourth aspects, when all of the second light source is turned off, the display color of the on-screen display by the display means is changed. It is characterized by that.

  A sixth invention of the present application is characterized in that, in the display device according to any one of the first to fifth inventions, when all of the second light source is turned off, image display by the display means is continued. And

  The seventh invention of the present application is characterized in that, in the display device of the sixth invention, the hue of the input video signal is changed when all of the second light source is turned off.

  According to an eighth aspect of the present invention, in the display device according to the seventh aspect, when all of the second light source is turned off, a change in hue of a display image due to the non-lighting of the second light source is compensated. In addition, the hue of the input video signal is corrected.

  According to a ninth aspect of the present invention, in the display device according to any one of the first to eighth aspects, the first light source is a cold cathode fluorescent lamp (CCFL).

  According to a tenth aspect of the present invention, in the display device according to any one of the first to eighth aspects, the second light source is a light emitting diode (LED).

  According to an eleventh aspect of the present invention, in the display device according to any one of the first to eighth aspects, the first light source is a light emitting diode (LED).

  A twelfth aspect of the present invention is the display device according to any one of the first to eighth aspects, wherein the second light source is a cold cathode fluorescent lamp (CCFL).

  According to the present invention, in a lighting device using a plurality of types of light sources that emit different colors, when a failure occurs in a light source that emits a certain color, the entire lighting device is not forced to be turned off. Since the non-lighting process is performed on all the types of light sources in which the light is generated and all other types of light sources are turned on, the user can continue to view the image without feeling uncomfortable, and the OSD displays the light source defects. Thus, user convenience can be improved.

  In addition, as described above, when other types of light sources continue to be lit, by correcting the hue of the image, it is possible to reduce the influence of the hue deviation of the illumination light due to the non-lighting of a certain type of light source. An easy-to-view video can be presented to improve user comfort.

  In addition, as described above, when other types of light sources are kept on, the OSD-displayed character color is set to a color that can be easily displayed by illumination light from other types of light sources, so that menu display, channel display, and warning can be performed. The display can be clearly displayed, and the clarity of information to the user can be improved.

  One embodiment of a display device of the present invention will be described with reference to FIGS. 1 to 6, for example, a liquid crystal display device. Here, FIG. 1 is an explanatory diagram showing the emission luminance levels of the respective wavelengths of the CCFL backlight light source and LED backlight light source in the present embodiment, and FIG. FIG. 3 is a flowchart showing an operation process when an LED backlight light source malfunctions in the liquid crystal display device of the present embodiment. FIG. 4 is an explanatory diagram showing an OSD display example of a backlight malfunction notification in the liquid crystal display device of the present embodiment. FIG. 5 is an explanatory diagram showing the display luminance level of each wavelength when the LED backlight light source is not lit in the liquid crystal display device of this embodiment, and FIG. 6 shows the operation processing when the CCFL backlight light source malfunctions in the liquid crystal display device of this embodiment. FIG.

  Here, the light source of the backlight device (illumination device) is composed of a three-wavelength fluorescent tube (hereinafter also referred to as CCFL) and a red monochromatic LED, and the red component of the CCFL is illumination light from the CCFL and the red monochromatic LED. A method for obtaining predetermined luminance and chromaticity by combining the above will be described. For example, as shown in FIG. 1, the CCFL color component is composed of λb (blue), λg (green), and λr (red), and the LED color component is λLED (red). ).

  As shown in FIG. 2, the liquid crystal display device according to the present embodiment performs image adjustment such as edge enhancement and gamma correction of an input video signal, and signal levels of R, G, and B that are color components of the video signal. Is provided with an image processing circuit 1 that can be varied independently. The operation of the image processing circuit 1 is mainly controlled by the microcomputer 4, and display data for menu, channel display, and the like is inserted from the OSD display unit 5. A video signal subjected to various image processing and image synthesis by the image processing circuit 1 is output to the liquid crystal panel controller 2.

  Further, a liquid crystal panel controller that displays an image on the liquid crystal panel 3 by controlling a transmission amount of the backlight illumination light through the liquid crystal panel 3 by controlling a source driver and a gate driver (not shown) according to the input video data. 2 is provided. The liquid crystal panel controller 2 is mainly controlled by the microcomputer 4. The contents of control by the microcomputer 4 are mainly various parameter settings according to the liquid crystal panel 3. The liquid crystal panel 3 is an aggregate of transmissive pixels having a matrix structure, and each element is composed of R, G, and B sub-pixels.

  Furthermore, the microcomputer 4 which performs image control and backlight control is provided. The microcomputer 4 performs image processing such as edge enhancement and noise removal by setting parameters of the image processing circuit 1. In addition, the hue of the display image is also changed by changing the signal levels of R, G, and B, which are the color components of the image.

  Further, by instructing the OSD display unit 5 with the character font and character color, the menu display, channel display, and warning display are combined and displayed on the image. The OSD display unit 5 determines actual display data according to the character font and character color data instructed by the microcomputer 4, generates a signal to be superimposed on the image, and outputs the signal to the image processing circuit 1.

  Further, the microcomputer 4 communicates with the WB control microcomputer 6 to obtain uncontrollable information such as white balance control of the LED backlight light source 10, abnormality of the color sensor of the LED backlight light source 10, disconnection of the LED backlight light source 10, and the like. . Further, the LED drive circuit 8 is controlled to turn on and off the LED backlight light source 10 and the fluorescent tube drive circuit 9 is controlled to turn on and off the CCFL backlight light source 11. To do.

  Further, failure information such as non-lighting of the CCFL backlight light source 11 is obtained from the failure detection circuit 13. Further, the microcomputer 4 and the WB control microcomputer 6 perform bidirectional communication, and when the WB control microcomputer 6 runs away, it can be detected on the microcomputer 4 side due to a communication abnormality.

  Then, the WB control microcomputer 6 performs white balance control of the LED backlight light source 10 and failure detection of the LED backlight light source 10. In the LED white balance control, the LED backlight light source 10 is adjusted so that the white balance (white point) of the entire backlight device is adjusted according to the measurement result of the color component of the illumination light of the entire backlight device obtained from the color sensor 7. Increase or decrease the light emission brightness. Further, the abnormal operation of the color sensor 7 and the LED breakage are detected and transmitted to the microcomputer 4. The color sensor 7 measures the color components of the illumination light of the entire backlight device as R, G, and B luminance levels.

  The LED drive circuit 8 supplies an appropriate current to the LED backlight light source 10. Further, the disconnection of the LED is detected by a change in the driving current and the information is transmitted to the microcomputer 4. The fluorescent tube driving circuit 9 is a circuit for driving the CCFL backlight light source 11 and controls turning on and off of the CCFL backlight light source 11.

  The LED backlight light source 10 irradiates the entire liquid crystal panel 3 by arranging a plurality of single red LEDs on the surface. Here, as shown in FIG. 1, the light component of the wavelength λled by the LED and the light component of the wavelength λr by the CCFL are combined into a red luminance component. The CCFL backlight light source 11 has a structure in which a plurality of CCFLs are arranged on the surface, and irradiates the entire liquid crystal panel 3. As shown in FIG. 1, the illumination light from the CCFL backlight light source 11 is composed of light components having wavelengths of λb, λg, and λr, and λr is combined with the light component of λled generated by the LED backlight light source 10. It becomes a red color component.

  The failure detection circuit 12 detects a failure of the CCFL backlight light source 11 and transmits it to the microcomputer 4. Which fluorescent tube among the plurality of CCFLs has a defect is detected.

  Next, the operation at the time of malfunction of the LED backlight light source in the liquid crystal display device having the above-described configuration will be described with reference to the flowchart of FIG. In FIG. 3, first, when the power of the liquid crystal display device is turned on (S1), the WB control microcomputer 6 is initialized (S2). Initialization is the setting of the luminance start level, control range, control cycle, etc. during white balance control. Then, it is determined whether or not the initialization of the WB control microcomputer 6 has failed (S3). This is because when the initialization fails, the WB control microcomputer 6 itself does not move and may not move at all including other parts. If it is determined that the initialization has failed, a process for turning off the power of the entire liquid crystal display device is performed for safety (S9).

  When the initialization of the WB control microcomputer 6 is completed, a CCFL lighting process is performed (S4). A CCFL lighting command is issued from the microcomputer 4 to the fluorescent tube driving circuit 9, and the fluorescent tube driving circuit 9 lights the CCFL backlight light source 11. Further, an LED lighting process is performed (S5). An LED lighting command is issued from the microcomputer 4 to the LED driving circuit 8, and the LED driving circuit 8 lights the LED backlight light source 10.

  Next, it is determined whether or not the color sensor 7 is operating normally (S6). The color sensor 7 measures the color components of the entire backlight, and specifically measures the luminance levels of red (R), green (G), and blue (B) that are color components. The abnormality of the color sensor 7 is determined by the WB control microcomputer 6 and is determined by showing an abnormal value such that all or some of the measurement results of R, G, B always show a constant value. The detection result is transmitted to the microcomputer 4. If the color sensor 7 is abnormal, the LED backlight source 10 is turned off (S10).

  If the color sensor 7 is abnormal, it is determined whether the LED is turned off (S7). When the LED in the LED backlight light source 10 is cut off, the LED drive current in the LED drive circuit changes. The change is detected and it is determined that the LED is out. The detection result is transmitted to the WB control microcomputer 6 and further to the microcomputer 4. When the LED break is detected, the LED backlight light source 10 is turned off (S10).

  If the LED is not cut off, it is determined whether the WB control microcomputer 6 has runaway (S8). While the liquid crystal display device is operating, the LED control microcomputer may run away. The cause may be a software defect in the WB control microcomputer 6 or static electricity. At that time, it is necessary to stop the LED backlight system related to the WB control microcomputer 6 for safety. Therefore, it is necessary to turn off the LCD backlight light source 10. When communication abnormality occurs between the microcomputer 4 and the WB control microcomputer 6, it is determined that the WB control microcomputer 6 is out of control. When it is determined that runaway occurs, the LED backlight source 10 is turned off (S10).

  S10 to S12 are processes when the LED backlight is abnormal. After performing this process, screen display, menu display, channel switching display, and the like of the input video signal are continuously performed (S13). That is, in S10, the microcomputer 4 instructs the LED drive circuit 8 to turn off the LED backlight light source 10, and turns off the LED. Next, in S11, the defect content of the LED backlight light source 10 is OSD-displayed. The displayed contents are “color sensor abnormality”, “LED disconnection”, “LED microcomputer abnormality”, and the like. An example of the OSD display is shown in FIG.

  Further, in S12, the green and blue signal levels of the input video signal are lowered by a predetermined amount. This is to compensate for a change in the color component balance of R, G, and B due to the red LED being turned off. As shown in FIG. 1, the wavelength distribution of the backlight by combining the CCFL and the LED in the normal state is that the LED has a wavelength of λLED. The combined light of λr and λLED has a red luminance level. When the LED is turned off, as shown in FIG. 5, the red display brightness level is lowered, so that the overall display brightness is lowered by lowering the levels of λb and λg accordingly, but the brightness balance of R, G, and B is reduced. Can take.

  Here, the correction for lowering the display luminance levels of green and blue is performed by lowering the G and B signal levels of the input video signal in the image processing circuit 1. The reduction amount of the signal level is determined in advance by calculation or measurement based on the luminance ratio between the CCFL and the LED.

  In S13, the OSD display color is changed to be composed of green and blue. Since the G and B levels of the input video signal are lowered in S12, it is conceivable to similarly reduce the G and B levels for the OSD signal. However, the visibility of the OSD display deteriorates due to the decrease in luminance. It will be.

  Therefore, the color elements of the OSD signal are made independent of the G and B signal levels of the video signal, and the visibility is prevented from being deteriorated by using only G and B without lowering the signal level. The design in which the character color is changed is stored in the microcomputer 4 in advance. By configuring the OSD display in green and blue, it is possible to display menus, channels, and warnings that are clearly visible even after the LEDs are turned off.

  After performing the processing as described above, normal operation including image display is continued (S14). As a result, the viewer can continue viewing the displayed image without feeling extreme discomfort even after the LED backlight light source 10 is not lit, and the defects of the LED backlight light source 10 can be clearly identified by OSD display. Can be recognized.

  Here, since not all of the LED backlight light source 10 in which a defect has occurred is turned off, but all of the LED backlight light source 10 is turned off, color unevenness and luminance unevenness in the screen do not occur. Therefore, it is possible to suppress the user's discomfort.

  Next, the operation at the time of malfunction of the CCFL backlight light source will be described with reference to the flowchart of FIG. In FIG. 6, first, when the power of the liquid crystal display device is turned on (S101), a CCFL lighting process is performed (S102). That is, a CCFL lighting command is issued from the microcomputer 4 to the fluorescent tube driving circuit 9, and the fluorescent tube driving circuit 9 turns on the CCFL backlight. Then, an LED lighting process is performed (S103). That is, an LED lighting command is issued from the microcomputer 4 to the LED driving circuit 8, and the LED driving circuit 8 lights the LED backlight 10.

  Further, it is determined whether there is a CCFL defect (S104). Here, the failure detection circuit 12 determines whether or not there is a failure in each CCFL for a plurality of CCFLs. The determination result is transmitted to the microcomputer 4. If there is a problem with the CCFL, the CCFL backlight 11 is turned off (S105). If the CCFL is not defective, the process of S104 described above is repeated.

  S105 to S107 are processes when the CCFL backlight is abnormal. After performing this process, screen display of the input video signal, menu display, channel switching, and the like are continuously performed (S108). That is, in S105, the microcomputer 4 instructs the fluorescent tube driving circuit 9 to turn off the CCFL backlight light source 11, and turns off the CCFL. Next, in S106, the trouble content of the CCFL backlight light source 11 is OSD-displayed. The displayed content is “CCFL error” or the like.

  In step S107, the OSD display color is changed to red. This is because the emission wavelength of the LED is only the red wavelength. Here, the design in which the character color is changed is stored in the microcomputer 4 in advance. By configuring the OSD display in red, the menu, channel display, and warning can be displayed even after the CCFL is turned off.

  After performing the processing as described above, normal operation including image display is continued (S108). Thus, the viewer can display a provisional video even after the CCFL backlight light source 11 is not lit, and can clearly recognize the malfunction of the CCFL backlight light source 11 by the OSD display.

  Here, the CCFL backlight light source 11 is not turned off, but the CCFL backlight light source 11 is turned off, so that color unevenness and luminance unevenness in the screen do not occur. Therefore, it is possible to suppress the user's discomfort.

  The display device of the present invention can be realized by various embodiments without departing from the gist of the present invention described above. For example, the hue change in the above-described embodiment may not be performed by the image processing circuit 1 but may be performed by changing the R, G, and B signal levels in the liquid crystal panel controller 2. Further, the above-mentioned LED backlight failure notification to the user may be performed not by OSD display but by blinking of a power ON / OFF confirmation LED or the like.

  In the above-described embodiment, the description has been given of the case where the backlight device using the combination of the CCFL that emits white light and the LED that emits red light is used. However, the present invention is not limited to this. Using various backlight devices such as a backlight device composed of a combination of CCFL that emits a component and an LED that emits a red color component, and a backlight device composed of LEDs each emitting three primary colors of red, green, and blue Also good.

  In the case of a backlight device that uses three or more types of light sources that emit different colors, such as LEDs that emit each of the three primary colors, turn off all the types of light sources that caused the failure and turn off all other light sources. Needless to say, it is sufficient to turn on the light and continue the image display.

It is explanatory drawing which shows the luminance level of each wavelength of the CCFL backlight light source and LED backlight light source in the liquid crystal display device of one Embodiment of this invention. It is a block diagram which shows the principal part schematic structural example in the liquid crystal display device of one Embodiment of this invention. It is a flowchart which shows the operation | movement process at the time of LED backlight light source failure in the liquid crystal display device of one Embodiment of this invention. It is explanatory drawing which shows the example of OSD display of the backlight malfunction notification in the liquid crystal display device of one Embodiment of this invention. It is explanatory drawing which shows the display luminance level of each wavelength at the time of LED backlight light source non-lighting in the liquid crystal display device of one Embodiment of this invention. It is a flowchart which shows the operation | movement process at the time of CCFL backlight light source failure in the liquid crystal display device of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image processing circuit 2 ... Liquid crystal panel controller 3 ... Liquid crystal panel 4 ... Microcomputer 5 ... OSD display part 6 ... WB control microcomputer 7 ... Color sensor 8 ... LED drive circuit 9 ... Fluorescent tube drive circuit 10 ... LED backlight light source 11 ... CCFL backlight light source 12 ... failure detection circuit

Claims (12)

An illumination device having a plurality of first light sources and second light sources that emit different colors;
In a display device comprising display means for displaying an image by modulating illumination light of the illumination device based on an input video signal,
When the luminance control for the second light source becomes impossible, the entire second light source is turned off and at least the first light source is turned on. An illumination device having a plurality of first light sources and second light sources that emit different colors;
In a display device comprising display means for displaying an image by modulating illumination light of the illumination device based on an input video signal,
When at least a part of the second light source is not turned on, the entire second light source is turned off and at least the first light source is turned on. In the display device according to claim 1 or 2,
A display device that notifies a user that all of the second light source has been turned off. The display device according to claim 3,
An on-screen display by the display means that all of the second light source is extinguished. The display device according to any one of claims 1 to 4,
A display device that changes a display color of on-screen display by the display means when all of the second light source is turned off. The display device according to any one of claims 1 to 5,
The display device, wherein the display unit continues to display an image when all of the second light sources are turned off. The display device according to claim 6,
A display device that changes the hue of the input video signal when all of the second light sources are turned off. The display device according to claim 7,
When the second light source is all turned off, the hue of the input video signal is corrected so as to compensate for the change in the hue of the display video due to the non-lighting of the second light source. apparatus. The display device according to any one of claims 1 to 8,
The display device, wherein the first light source is a cold cathode tube. The display device according to any one of claims 1 to 8,
The display device, wherein the second light source is a light emitting diode. The display device according to any one of claims 1 to 8,
The display device, wherein the first light source is a light emitting diode. The display device according to any one of claims 1 to 8,
The display device, wherein the second light source is a cold cathode tube.

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