JP2012220889A - Dimmer control device and display control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dimmer control device capable of suppressing the lowering of visibility of a display image by a dimmer control, and a display control device.SOLUTION: The dimmer control device is configured to cause a dimmer control section to select luminance information that is set for each type of an image and represents a correspondence between an illuminance in the periphery of the display device and a light emission luminance of a backlight of the display device, according to the type of an image to be displayed by the display device; to control the light emission luminance of the backlight according to the luminance information; and to perform the dimmer control according to the illuminance in the periphery of the display device.

Description

  The present invention relates to a dimmer control device and a display control device.

  2. Description of the Related Art Conventionally, there is known a dimmer control device that reduces power consumption by reducing the light emission luminance of a backlight of a display device so that a display image becomes dark according to a decrease in brightness around the display device.

  By the way, in the dimmer control device, for example, when the dimmer control is performed to reduce the light emission luminance of the backlight as the surrounding brightness decreases while displaying a relatively dark image, the display image becomes darker and the display image becomes darker. Visibility may be reduced.

  In view of this, a device has been devised that analyzes the data of the video displayed by the display device and changes the contents of the dimmer control according to the brightness of the video.

  For example, Patent Document 1 previously stores a plurality of dimming curve data in which peripheral brightness and backlight emission luminance are associated with each other, and the dimming curve corresponding to the average luminance of the video calculated from the display video data. An apparatus for controlling the light emission luminance of the backlight is disclosed.

JP 2009-192717 A

  However, since the conventional apparatus performs the same dimmer control regardless of the image type, for example, a display that needs to be displayed brighter than other images for safety, such as an image around a vehicle captured by a camera. Even in the case of an image, the displayed image may become dark, which is not preferable.

  For this reason, how to realize a dimmer control device and a display control device that can suppress a decrease in the visibility of a display image due to dimmer control is a major issue.

  The present invention has been made in view of the above, and an object of the present invention is to provide a dimmer control device and a display control device capable of suppressing a reduction in the visibility of a display image due to dimmer control.

  In order to solve the above-described problems and achieve the object, the present invention is a dimmer control device that controls the light emission luminance of the backlight of the display device according to the illuminance around the display device, and for each video type. A dimmer control that selects the luminance information according to the type of video displayed by the display device from luminance information that is set and indicates the correspondence between the illuminance and the luminance, and controls the luminance according to the luminance information It has the part.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the dimmer control apparatus and display control apparatus which can suppress the fall of the visibility of the display image by dimmer control can be provided.

FIG. 1 is a diagram showing an outline of a dimmer control method according to the present invention. FIG. 2 is a block diagram illustrating the configuration of the display control apparatus according to the present embodiment. FIG. 3 is a diagram illustrating an example of the luminance information selection table according to the present embodiment. FIG. 4 is a diagram illustrating an example of luminance information according to the present embodiment. FIG. 5 is a flowchart showing main processing executed by the dimmer control device according to the present embodiment. FIG. 6 is a flowchart illustrating the luminance information selection process in the main process executed by the dimmer control device according to the present embodiment. FIG. 7 is a diagram illustrating an example of the second luminance information according to the first modification. FIG. 8 is a diagram illustrating a relationship between the dimmer lower limit value and the brightness setting value according to the second modification.

  Exemplary embodiments of a dimmer control device and a display control device to which a dimmer control method according to the present invention is applied will be described below in detail with reference to the accompanying drawings. In the following, the outline of the dimmer control method according to the present invention will be described with reference to FIG. 1, and then an embodiment of a display control device to which the dimmer control method according to the present invention is applied will be described with reference to FIGS. I will explain.

  FIG. 1 is a diagram showing an outline of a dimmer control method according to the present invention. A dimmer control device to which the dimmer control method according to the present invention is applied (hereinafter referred to as “the present dimmer control device”) has a brightness of an environment (hereinafter simply referred to as “periphery”) provided with a display device. It is a device that performs dimmer control on the light emission luminance of the backlight of the display device in accordance with the illuminance shown.

  For example, the dimmer control device reduces power consumption by reducing the light emission luminance of the backlight as the ambient illuminance decreases. Furthermore, the present dimmer control device suppresses a decrease in the visibility of the display video due to the dimmer control by changing the content of the dimmer control according to the type of the video displayed by the display device, while having a simple configuration. It is configured.

  Specifically, as shown in FIG. 1, the dimmer control device includes a storage unit and a dimmer control unit. The storage unit stores luminance information indicating a correspondence relationship between ambient illuminance and backlight emission luminance for each video type.

  Each luminance information is information that defines the emission luminance of the backlight corresponding to the ambient illuminance for each type of video so as to prevent a reduction in the visibility of the displayed video and reduce power consumption. A specific example of luminance information will be described later with reference to FIG.

  The dimmer control unit selects luminance information according to the type of video displayed by the display device, and controls the light emission luminance of the backlight that irradiates the display panel with light according to the selected luminance information.

  For example, when a predetermined operation unit is operated and a video of type A is displayed on the display panel of the display device, the dimmer control unit displays video type information indicating that the video type of the display video is A from the operation unit. Is acquired (step S1). That is, the dimmer control unit acquires, as video type information, an operation signal output by the operation unit when a display video type determining operation is performed.

  Subsequently, the dimmer control unit acquires luminance information for video type A corresponding to the acquired video type information from the storage unit (step S2). Subsequently, the dimmer control unit obtains illuminance indicating ambient brightness from the illuminance sensor (step S3).

  Then, the dimmer control unit outputs a control signal generated based on the illuminance acquired from the illuminance sensor and the luminance information for video type A acquired from the storage unit to the backlight (step S4), so that the video type A The backlight emits light with a brightness suitable for the image.

  In this way, the dimmer control device stores in advance the luminance information that defines the correspondence between the ambient illuminance and the appropriate light emission luminance of the backlight for each video type, and stores the luminance information corresponding to the type of display video. Select and dimmer control the backlight based on the luminance information and illuminance. Therefore, this dimmer control apparatus can suppress the fall of the visibility of the display image by dimmer control.

  For this reason, this dimmer control device uses luminance information dedicated to the camera in the case of a display image that needs to be displayed brighter than other images for safety, such as an image around the vehicle imaged by the camera. Thus, the light emission luminance of the backlight can be adjusted appropriately. This point will be specifically described in the embodiments described later.

  Below, the Example about the display control apparatus to which the dimmer control method demonstrated using FIG. 1 is applied is described in detail. In the following embodiments, a display control device that controls an in-vehicle display device will be described as an example. However, the dimmer control method according to the present invention is not limited to an in-vehicle display device, and a display that controls an arbitrary display device. It can be applied to a control device.

  FIG. 2 is a block diagram illustrating a configuration of the display control apparatus 1 according to the present embodiment. The display control device 1 is a device that controls the light emission luminance of a backlight that irradiates light to the display panel of the display device and performs video correction that improves the visibility of the display video according to the illuminance around the display device.

  Specifically, as shown in FIG. 2, the display control device 1 includes a video information acquisition unit 2, a direct-light correction unit 3, an illuminance sensor 4, a backlight control unit 5, a dimmer control device 6, and a multiplication unit 7. Yes. The portion other than the illuminance sensor 4 in the display control device 1 is an ASIC (Application Specific Integrated Circuit) specially designed to perform image correction and backlight operation control.

  The video information acquisition unit 2 is a processing unit that acquires video information from a video signal input from each device serving as a video source and outputs the video information to the direct light correction unit 3 and the backlight control unit 5. Here, a case where a video signal is input to the video information acquisition unit 2 from a camera and a car navigation device that captures the periphery of the vehicle will be described.

  Note that the car navigation apparatus outputs video signals of videos having different background colors between daytime and nighttime to the video information acquisition unit 2. For example, a car navigation device outputs a video signal for daytime images with a bright background color when the vehicle headlamps are turned off, and is used for daytime when the headlamps are turned on. The video signal of the video for the night whose background color is darker than the video of is output.

  Hereinafter, the video signal output from the camera is referred to as “camera video”, and the video signal video output from the car navigation device is referred to as “navigation video”. The device that outputs the video signal to the video information acquisition unit 2 may be an arbitrary video source such as a DVD (Digital Versatile Disc) playback device or a digital television broadcast receiver.

  The illuminance sensor 4 is a sensor that detects illuminance indicating the brightness around the display device and outputs the detected illuminance to the direct light correction unit 3 and the dimmer control device 6.

  The direct-light correction unit 3 corrects video information according to the illuminance input from the illuminance sensor 4 and outputs the corrected video information to the video compensation unit 34 in order to suppress a decrease in the visibility of the displayed video due to the influence of direct sunlight or the like. Part. Specifically, the direct-light correction unit 3 includes a visibility correction unit 31, a saturation correction unit 32, and a blend unit 33.

  The visibility correction unit 31 performs edge correction on the video information input from the video information acquisition unit 2 so as to make the contour portion included in the display video stand out, and sends the corrected video information to the saturation correction unit 32. It is a processing part to output.

  The saturation correction unit 32 performs gradation correction on the video information input from the visibility correction unit 31 so that the intermediate color included in the display video is close to the primary color, and outputs the corrected video information to the blending unit 33. Is a processing unit. The visibility correction unit 31 and the saturation correction unit 32 generate video information that is corrected so that the visibility is most improved under a situation where the influence of direct sunlight or the like is the strongest.

  The blend unit 33 blends the uncorrected video information input from the video information acquisition unit 2 and the corrected video information input from the saturation correction unit 32 with a blend ratio according to the illuminance input from the illuminance sensor 4. A processing unit that blends and outputs the blended video information to the video compensation unit 34.

  The blending unit 33 blends so that the higher the illuminance input from the illuminance sensor 4, the higher the blending ratio of the corrected video information in the video information after blending, and the lower the blending ratio of the video information before correction. Adjust the ratio.

  When the video information is input from the video information acquisition unit 2, the backlight control unit 5 creates a luminance histogram of the input video, and sets the backlight duty ratio to an upper limit value (for example, 80%) according to the luminance of the input video. This is a processing unit that calculates in the following range and outputs a control signal for causing the backlight to emit light to the backlight via the multiplication unit 7 and outputs the calculated duty ratio to the video compensation unit 34.

  The video compensation unit 34 compensates the luminance of the video by the amount of light reduced by the backlight control unit 5 so as to be the same as when the input video is emitted with a duty ratio of 100%, and supplies the supplemented video information to the display panel. It is a processing part to output. The backlight emits light with an emission luminance corresponding to the duty ratio of the control signal input from the display control device 1.

  For example, the backlight emits light (lights up) when the duty ratio is 100%, and turns off when the duty ratio is 0%. Then, the backlight control unit 5 outputs a control signal whose duty ratio corresponds to the luminance of the input video to the multiplication unit 7 during a period in which the video information is input from the video information acquisition unit 2.

  The multiplication unit 7 is a processing unit that outputs to the backlight a control signal in which the duty ratio is adjusted by multiplying the duty ratio input from the backlight control unit 5 by the duty ratio input from the dimmer control device 6. Yes, and constitutes a final luminance value calculation unit.

  That is, for example, when a duty ratio of 80% is input from the backlight control unit 5 and a duty ratio of 50% is input from the dimmer control device 6, the multiplication unit 7 backs up a control signal having a duty ratio of 40%. By outputting to the light, the backlight is caused to emit light with a light emission luminance of 2/5 of the maximum light emission luminance.

  The dimmer control device 6 is a device that reduces the power consumption of the backlight while maintaining the visibility of the display image by controlling the duty ratio of the control signal output to the backlight according to the illuminance around the display device. . The dimmer control device 6 performs control to reduce the light emission luminance of the backlight as the illuminance around the display device decreases.

  Specifically, the dimmer control device 6 includes a storage unit 8 and a dimmer control unit 9. The storage unit 8 stores, for each video type, a plurality of pieces of luminance information indicating a correspondence relationship between the illuminance around the display device and the light emission luminance of the backlight.

  In the example illustrated in FIG. 2, the storage unit 8 includes first luminance information 81, second luminance information 82, and third luminance that define a correspondence relationship between appropriate backlight luminance and illuminance for each video type. Four types of luminance information, that is, information 83 and fourth luminance information 84 are stored. The storage unit 8 can store an arbitrary number of luminance information. Specific examples of the first to fourth luminance information 81, 82, 83, and 84 will be described later with reference to FIG.

  Further, the storage unit 8 stores a luminance information selection table 85 that is referred to by the dimmer control unit 9 to select luminance information corresponding to the type of display video. A specific example of the luminance information selection table 85 will be described later with reference to FIG.

  The first to fourth luminance information 81, 82, 83, 84 and the luminance information selection table 85 are stored in an external storage device by an information reading processing unit (not shown) when the display control device 1 is powered on. (Not shown) is read out and stored in the storage unit 8.

  The dimmer control unit 9 calculates the luminance of the backlight based on the selection unit 91 that selects the luminance information corresponding to the display image, the luminance information selected by the selection unit 91, and the illuminance detected by the illuminance sensor 4. And a luminance value calculation unit 92 for performing the above operation.

  The selection unit 91 is a processing unit that selects luminance information based on day / night information and video type information input from a predetermined operation unit provided in the vehicle. When the user of the vehicle operates a predetermined operation unit, the selection unit 91 acquires an operation signal input from the operation unit as day / night information or video type information.

  For example, when the user operates a switch for displaying a camera video, the selection unit 91 acquires an operation signal input from the switch as video type information, and a video indicating that the video type is a camera video Stored as type information in an internal memory (not shown).

  In addition, for example, when the user operates a predetermined switch to turn on a vehicle headlamp or a vehicle width lamp, the selection unit 91 acquires an operation signal input from the switch as day / night information, and sets the night time. The stored day / night information is stored in an internal memory (not shown).

  In addition, when the user operates a predetermined switch to turn off the vehicle headlamp or the vehicle width lamp, the selection unit 91 acquires an operation signal input from the switch as day / night information, and day / night indicating daytime. Information is stored in an internal memory (not shown).

  The selection unit 91 obtains luminance information corresponding to the type of display video determined based on the video type information and the day / night determination result determined based on the day / night information from the first to fourth luminance information 81, 82, Select from 83 and 84 and output to luminance value calculation unit 92.

  Note that the selection unit 91 may be configured to determine daytime when the illuminance detected by the illuminance sensor 4 is greater than or equal to a predetermined threshold, and to determine nighttime when the illuminance is less than the threshold. Good.

  Here, a specific example of the luminance information selection table 85 and a procedure for selecting luminance information by the selection unit 91 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of the luminance information selection table 85 according to the present embodiment.

  As shown in FIG. 3, the luminance information selection table 85 is information in which luminance information, day / night information, and video type are associated with each other. Specifically, the first luminance information 81 is associated with day / night information called daytime and a video type called navigation video.

  The second luminance information 82 is associated with day / night information at night and a video type called navigation video. The third luminance information 83 is associated with day / night information of daytime and the video type of camera video, and the fourth luminance information 84 is day / night information of night and the video type of camera video. Are associated with each other.

  And the selection part 91 discriminate | determines day and night based on the day and night information input from the predetermined | prescribed operation part provided in the vehicle, and also displays on a display apparatus based on the image | video classification information input from the predetermined | prescribed operation part. The type of video to be played is determined.

  As described above, the selection unit 91 functions as a day / night discrimination unit that discriminates day and night, and also functions as a type discrimination unit that discriminates the type of display video. Subsequently, the selection unit 91 selects luminance information associated with the day / night discrimination result and the video type discrimination result in the luminance information selection table 85.

  Thereby, the selection part 91 can select the suitable brightness | luminance information according to the time according to the kind of image | video displayed by a display apparatus, and the difference in daytime. Here, specific examples of the first to fourth luminance information 81, 82, 83, and 84 will be described with reference to FIG.

  FIG. 4 is a diagram illustrating an example of the luminance information (first to fourth luminance information 81, 82, 83, and 84) according to the present embodiment. In addition, each horizontal axis of the 1st-4th brightness information 81, 82, 83, and 84 shown in FIG. 4 has shown the illumination intensity (Lx) detected by the illumination intensity sensor 4, and each vertical axis | shaft is to a backlight. The duty ratio (%) of the output control signal is shown.

  As shown in FIG. 4, the first luminance information 81 and the second luminance information 82 are luminance information for navigation video. Among these, the first luminance information 81 is daytime luminance information, and the second luminance information. Information 82 is luminance information for nighttime.

  The third luminance information 83 and the fourth luminance information 84 are luminance information for a camera image in which the periphery of the vehicle is imaged. Among these, the third luminance information 83 is luminance information for daytime, and the fourth luminance. Information 84 is nighttime luminance information.

  These first to fourth luminance information 81, 82, 83 and 84 are functions (hereinafter referred to as “characteristic functions”) indicating the relationship between the illuminance detected by the illuminance sensor 4 and the duty ratio of the control signal output to the backlight. Is described).

  In FIG. 4, for ease of explanation, the characteristic function corresponding to each piece of luminance information is shown by a graph. However, the characteristic function is stored in the storage unit 8 as a function expression corresponding to each graph shown in FIG. Is done.

  Each of the first to third luminance information 81, 82, and 83 includes 11 types of characteristic functions having different duty ratios corresponding to illuminance, and the user selects a desired characteristic function from the 11 types of characteristic functions. This makes it possible to change the luminance of the backlight.

  Among these 11 types of characteristic functions, each characteristic function having an intermediate duty ratio (sixth from the lowest duty ratio) is a characteristic function used as a default when the luminance value calculation unit 92 calculates the luminance value. (Hereinafter referred to as “default function”).

  By the way, as described above, the night navigation video has a darker background color than the daytime navigation video. For this reason, the visibility of the nighttime navigation video is not greatly reduced even if the light emission luminance of the backlight is reduced. Therefore, the second luminance information 82 corresponding to the nighttime navigation video defines a lower duty ratio (backlight emission luminance) corresponding to the illuminance than the first luminance information 81 corresponding to the daytime navigation video. ing.

  As a result, when the navigation video is displayed at night, by controlling the light emission luminance of the backlight using the second luminance information 82, the visibility of the navigation video is suppressed from being lowered and lower than the daytime. Navigation video can be displayed with power consumption.

  In addition, the camera video needs to be displayed brighter than the navigation video from the viewpoint of vehicle driving safety. Therefore, the third luminance information 83 corresponding to the daytime camera image defines a higher duty ratio (backlight emission luminance) corresponding to the illuminance than the first luminance information 81 corresponding to the daytime navigation image. Yes.

  Thereby, when displaying a camera image in the daytime, by controlling the light emission luminance of the backlight using the third luminance information 83, the camera image can be displayed brighter than when displaying the navigation image. For this reason, it can prevent that the safety | security of vehicle driving | running | working falls.

  In addition, since the camera image becomes dark around the vehicle at night, the displayed image itself becomes dark. Therefore, if dimmer control is performed on the night camera image to reduce the light emission brightness of the backlight in accordance with the decrease in illuminance, the display image becomes darker, which is not preferable in terms of vehicle safety.

  Therefore, the fourth luminance information 84 that is the luminance information for the night of the camera image is defined such that the duty ratio (light emission luminance of the backlight) is the highest (100%) regardless of the illuminance detected by the illuminance sensor 4. is doing.

  Note that 100% is an example, and if it is too bright at a duty ratio of 100% at night, it can be lowered to a duty ratio smaller than 100%. The duty ratio may be larger than the maximum duty of the 2 luminance information.

  Accordingly, when displaying the camera image at night, the luminance of the backlight is controlled by using the fourth luminance information 84, thereby preventing a decrease in the visibility of the camera image due to the dimmer control and the vehicle traveling safety. Sex can be secured.

  As described above, the first to fourth luminance information 81, 82, 83, and 84 are used to prevent a reduction in safety due to a decrease in visibility or consumption depending on the type of video displayed by the display device or the difference between day and night. The duty ratio corresponding to the illuminance is specified so that the light emission luminance is suitable for reducing the power.

  Thus, the dimmer control device 6 performs complicated processing only by determining the type of display video, selecting luminance information corresponding to the determined type of display video, and using it for controlling the light emission luminance of the backlight. In addition, appropriate dimmer control according to the type of display video can be performed. For this reason, although the dimmer control apparatus 6 is a simple structure, it can suppress the fall of the visibility of the display image by dimmer control.

  Returning to the description of FIG. 2, the luminance value calculation unit 92 is based on the illuminance input from the illuminance sensor 4 and the luminance information selected by the selection unit 91, and the duty ratio of the control signal corresponding to the light emission luminance of the backlight. Is a processing unit that calculates and outputs to the multiplication unit 7.

  The luminance value calculation unit 92 selects a default function from the luminance information input from the selection unit 91 and the illuminance input from the illuminance sensor 4 to the default function when the setting of the light emission luminance of the backlight is not changed by the user. Is used to calculate the duty ratio.

  On the other hand, the luminance value calculation unit 92 acquires, as brightness setting information, an operation signal input from a predetermined operation unit when the user performs an operation to change the light emission luminance of the backlight with respect to the predetermined operation unit. To do.

  Then, the luminance value calculation unit 92 reads the characteristic function corresponding to the brightness setting information from the luminance information input from the selection unit 91, and calculates the duty ratio by substituting the illuminance input from the illuminance sensor 4 into the characteristic function. To do.

  Subsequently, the luminance value calculation unit 92 outputs the calculated duty ratio to the multiplication unit 7, so that a control signal having a duty ratio according to the type of video, the difference between day and night, or the user setting is output from the multiplication unit 7. To control the luminance of the backlight.

  Next, main processing executed by the dimmer control device 6 will be described. FIG. 5 is a flowchart illustrating main processing executed by the dimmer control device 6 according to the present embodiment.

  As shown in FIG. 5, when the power is turned on to the dimmer control device 6, the information reading processing unit (not shown) is connected to the first to fourth luminance information 81, 82, and the like from an external storage device (not shown). 83 and 84 are read and stored in the storage unit 8 (step S101).

  At this time, the information reading processing unit reads other information necessary for the dimmer control, such as the luminance information selection table 85 and the luminance sampling timing, from the external storage device and stores them in the storage unit 8.

  Subsequently, the selection unit 91 performs luminance information selection processing for selecting luminance information corresponding to the type of display video and the day / night discrimination result (step S102). Details of the luminance information selection processing will be described later with reference to FIG.

  Subsequently, the luminance value calculation unit 92 determines whether or not it is the sampling timing (step S103), and when it is determined that it is not the sampling timing (step S103, No), the determination process of step S103 is repeated until the sampling timing is reached. If the luminance value calculation unit 92 determines that it is the sampling timing (step S103, Yes), the luminance value calculation unit 92 acquires the illuminance from the illuminance sensor 4 (step S104).

  Subsequently, the luminance value calculation unit 92 calculates the duty ratio of the control signal output to the backlight based on the luminance information selected by the process of step S102 and the illuminance acquired by the process of step S104 (step S105). ).

  At this time, the luminance value calculation unit 92 calculates the duty ratio using the default function in the luminance information selected in the process of step S102 when the user has not performed an operation of changing the light emission luminance of the backlight.

  On the other hand, the luminance value calculation unit 92 responds to the user's operation when the luminance information other than the fourth luminance information 84 is selected in the process of step S102 and the user performs an operation of changing the light emission luminance of the backlight. The duty ratio is calculated using the characteristic function.

  Subsequently, the luminance value calculation unit 92 outputs the duty ratio calculated in step S105 to the multiplication unit 7 (step S106), and determines whether the power is turned off (step S107). If the luminance value calculation unit 92 determines that the power is not turned off (No in step S107), the process proceeds to step S102. On the other hand, if the luminance value calculation unit 92 determines that the power has been turned off (Yes in step S107), the process ends.

  Next, the luminance information selection process in the main process will be described with reference to FIG. FIG. 6 is a flowchart showing the luminance information selection process in the main process executed by the dimmer control device 6 according to this embodiment.

  As shown in FIG. 6, when the luminance information selection process is started, the selection unit 91 determines that the type of video displayed by the display device is a camera based on the video type information stored in the internal memory (not shown). It is determined whether or not the image is a video (step S201).

  When the selection unit 91 determines that the video type is not a camera video (No in step S201), the selection unit 91 determines whether it is daytime based on the day / night information stored in the internal memory (not shown) (step S201). S202).

  If the selection unit 91 determines that it is daytime (step S202, Yes), the first luminance information 81 is selected (step S203), and the process proceeds to step S103 illustrated in FIG. On the other hand, when the selection unit 91 determines that it is nighttime (No in Step S202), the second luminance information 82 is selected (Step S204), and the process proceeds to Step S103 illustrated in FIG.

  If the selection unit 91 determines that the type of video displayed by the display device is a camera video (Yes in step S201), the selection unit 91 determines whether it is daytime (step S205). If the selection unit 91 determines that it is daytime (Yes at Step S205), the selection unit 91 selects the third luminance information 83 (Step S206), and moves the process to Step S103 illustrated in FIG. On the other hand, when the selection unit 91 determines that it is nighttime (No at Step S205), the fourth luminance information 84 is selected (Step S207), and the process proceeds to Step S103 illustrated in FIG.

  As described above, the dimmer control device according to the present embodiment previously stores luminance information indicating the correspondence between the illuminance around the display device detected by the illuminance sensor and the light emission luminance of the backlight of the display device for each video type. Remember. The dimmer control device according to the present embodiment selects luminance information according to the type of video displayed by the display device, and performs dimmer control on the light emission luminance of the backlight according to the selected luminance information.

  Thus, the dimmer control device according to the present embodiment determines the type of display video, and performs the dimmer control based on the luminance information corresponding to the determined video type. A reduction in the visibility of the video can be suppressed.

  Further, the dimmer control device according to the present embodiment stores the luminance information for daytime and the luminance information for nighttime for each type of video, and based on the luminance information selected according to the determination result of determining daytime and nighttime. Controls the luminance of the backlight.

  Thereby, the dimmer control device according to the present embodiment, for example, in the case of a display image provided from a device that outputs images with different brightness at day and night, such as a camera or a car navigation device that images the periphery of the vehicle, Appropriate dimmer control can be performed according to the difference between day and night.

  Further, in the dimmer control device according to the present embodiment, out of the luminance information for night, the luminance information related to the image around the imaging device captured by the imaging device is emitted corresponding to the illuminance rather than the luminance information other than the luminance information. The brightness is specified to be high.

  Thereby, the dimmer control device according to the present embodiment displays, for example, a video that is brighter than video provided from other video sources when a video around the vehicle imaged by the imaging device is displayed. It is possible to ensure safety by suppressing a decrease in visibility.

  Further, in the dimmer control device according to the present embodiment, the luminance information other than the luminance information for night related to the image around the imaging device captured by the imaging device has different characteristics of the change in the emission luminance of the backlight accompanying the change in illuminance. Each has a plurality of characteristic functions.

  And when the selection operation which selects a characteristic function is performed, the dimmer control apparatus which concerns on a present Example controls the light emission luminance of a backlight based on the characteristic function corresponding to selection operation. As a result, the dimmer control device according to the present embodiment can control the luminance of the backlight so as to achieve the light emission luminance desired by the user within a predetermined luminance range corresponding to the type of display video.

  By the way, in the above-described embodiment, the case where the backlight of the in-vehicle display device is dimmer controlled has been described. However, the dimmer control device according to the present embodiment is a display device that displays an image of a security camera provided in a building. The backlight can also be dimmer controlled.

  In addition, in the above-described embodiment, the luminance information defined so that the backlight emission luminance decreases as the illuminance decreases is given as an example other than the luminance information for the night of the camera image. The luminance information stored by the dimmer control device is not limited to this.

  That is, the dimmer control device according to the present embodiment is, for example, a luminance that is associated with a constant light emission luminance regardless of the illuminance around the display device if the luminance information of the backlight is different for each video type. Information may be stored.

  Next, Modification 1 and Modification 2 of the above-described embodiment will be described with reference to FIGS. FIG. 7 is a diagram illustrating an example of the second luminance information according to the first modification. FIG. 8 is a diagram illustrating a relationship between the duty ratio lower limit value and the brightness setting value according to the second modification.

(Modification 1)
In the above embodiment, the dimmer control is performed on the navigation video for both daytime and nighttime. That is, as shown in FIG. 4, control is performed to reduce the duty ratio when the illuminance decreases for both daytime and nighttime use.

  The dimmer control is used to smooth the screen brightness from a screen with high daytime brightness to a screen with low nighttime brightness by gradually decreasing the amount of backlight light when the surroundings are dim, such as when driving in the evening or in a tunnel. Used to connect.

  However, at night, the surroundings remain dark, and the dimmer control is performed even though the ambient illuminance hardly changes, leading to an increase in power consumption. Further, when the ambient illuminance changes due to the influence of a streetlight or the like, the light amount of the backlight also changes according to the change. Furthermore, since dimmer control is performed with a low backlight light intensity at night, the change in the light intensity due to the change in the illumination is conspicuous, leading to an increase in flicker and noise.

  Therefore, in the first modification, the dimmer control is prohibited when it is determined at night. For example, taking a navigation video as an example, the second luminance information for night shown in FIG. 4 is transformed as shown in FIG. That is, the duty ratio is prevented from changing in a low-illuminance region α corresponding to night.

  In this example, nighttime is determined by the illuminance value. If nighttime is determined by the day / night information shown in FIG. 2, a method of fixing to the immediately preceding duty ratio when switching from a daytime video to a nighttime video based on the day / night information may be used. Thus, according to the modification 1, power consumption can be reduced and flicker and noise can also be reduced.

  Although the first modification is applied to a night navigation video, it can also be applied to a video that does not have daytime and nighttime video such as a TV video. In this case, the luminance information may be luminance information having a single characteristic as shown in FIG.

  The first modification is not only applied to the dimmer control that controls the light emission luminance in accordance with the type of video, but can be applied to the entire dimmer control that controls the light emission luminance in accordance with the ambient illuminance.

(Modification 2)
In the backlight control, a duty ratio lower limit value (for example, 3%) determined by the operation characteristics of the light emitting element is set in order to ensure the control operation. The multiplication unit 7 in FIG. 2 has such a lower limit value, and limits the final output duty ratio so as not to be lower than the lower limit value.

  Here, the backlight control unit 5 determines the duty ratio of the backlight according to the luminance of the input video, determines the video compensation amount so that the video does not appear to change, and the video compensation unit 34 compensates the video. However, since the luminance of the input video changes for each frame, the duty ratio and the video compensation amount change accordingly.

  However, when the multiplication unit 7 multiplies the duty ratio calculated by the dimmer control unit 9 and the duty ratio calculated by the backlight control unit 5 and continues to be below the lower limit value, the final output duty ratio becomes the lower limit value. The amount of video compensation will change even though it remains unchanged.

  For this reason, a flickering feeling is given to the user. This phenomenon becomes prominent particularly when the user sets the lowest duty ratio characteristic at night. This is because, as is apparent from the first luminance information and the second luminance information shown in FIG. 4, the duty ratio is set relatively low at night compared to daytime.

  In the second modification, therefore, a lower limit value is also set for the duty ratio of the backlight calculated by the backlight control unit 5 (hereinafter, the lower limit value of the multiplication unit 7 is the first lower limit value, and the lower limit value of the backlight control unit 5). Is referred to as a second lower limit value).

  The second lower limit value may be constant, but it is preferable to vary the lower limit value according to the brightness setting information set by the user as shown in FIG. That is, the second lower limit value is set lower as the brightness setting value is larger, in other words, as the maximum duty ratio is larger.

  For this purpose, the brightness setting information is also input to the backlight control unit 5 in FIG. When the brightness setting value is large, the duty ratio output from the dimmer control unit 9 is also large, so that the second lower limit value of the backlight control unit 5 can be lowered by that amount within a range that does not fall below the first lower limit value. Thereby, further power saving can be achieved.

  Therefore, according to the second modification, it is possible to suppress the flickering of the video, and to further save power by changing the lower limit value according to the brightness setting information. The modification 2 is not only applied to the dimmer control that controls the light emission luminance according to the type of video, but can be applied to all the dimmer control that controls the light emission luminance according to the ambient illuminance.

DESCRIPTION OF SYMBOLS 1 Display control apparatus 2 Image | video information acquisition part 3 Direct sunlight correction | amendment part 31 Visibility correction | amendment part 32 Saturation correction | amendment part 33 Blend part 4 Illuminance sensor 5 Backlight control part 6 Dimmer control apparatus 7 Multiplication part 8 Memory | storage part 81 1st brightness | luminance information 82 Second luminance information 83 Third luminance information 84 Fourth luminance information 85 Luminance information selection table 9 Dimmer control unit 91 Selection unit 92 Luminance value calculation unit

Claims (7)

A dimmer control device for controlling the light emission luminance of the backlight of the display device according to the illuminance around the display device,
The luminance information is selected according to the type of video displayed by the display device from the luminance information that is set for each type of video and indicates the correspondence between the illuminance and the luminance of light emission, and the light emission luminance is determined according to the luminance information. A dimmer control device comprising: a dimmer control unit for controlling the control. A storage unit for storing the luminance information;
And a discriminator for discriminating day and night,
The storage unit
Store the luminance information for daytime and the luminance information for nighttime for each type of video,
The dimmer control unit
The dimmer control device according to claim 1, wherein the luminance information is selected according to a determination result by the determination unit. Among the luminance information for nighttime, the luminance information related to the image around the imaging device captured by the imaging device has a higher emission luminance corresponding to the illuminance than the luminance information other than the luminance information. The dimmer control device according to claim 2. The luminance information other than the luminance information for night related to the image around the imaging device includes a plurality of characteristic functions each having a different change characteristic of the light emission luminance accompanying the change in the illuminance,
The dimmer control unit
The dimmer control device according to claim 3, wherein, when a selection operation for selecting the characteristic function is performed, the light emission luminance is controlled based on the characteristic function corresponding to the selection operation. With a means to detect the night,
5. The dimmer control device according to claim 1, wherein when it is detected that it is nighttime, the control of the light emission luminance according to the illuminance is prohibited. A backlight control unit for controlling the light emission luminance of the backlight according to the luminance of the displayed image;
According to the light emission luminance value calculated by the backlight control unit, a video compensation unit that compensates the luminance of the displayed video;
A final luminance value calculation unit for determining a final luminance value within a range equal to or higher than a first lower limit value based on the luminance value calculated by the backlight control unit and the luminance value calculated by the dimmer control unit; In addition,
The backlight control unit calculates a light emission luminance value in a range equal to or greater than a second lower limit value whose value changes according to brightness setting information for changing the light emission luminance of the backlight by a user operation. The dimmer control device according to any one of claims 1 to 5. A display control device that controls the light emission luminance of the backlight of the display device according to the illuminance around the display device,
An illuminance detector for detecting the illuminance;
The luminance information is selected according to the type of video displayed by the display device from the luminance information that is set for each type of video and indicates the correspondence between the illuminance and the luminance of light emission, and the light emission luminance is determined according to the luminance information. And a dimmer control unit for controlling the display.

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