Patent ID: 12222600

DETAILED DESCRIPTION

In general, according to one embodiment, a display device includes a display panel including a display area which displays images, a plurality of light sources irradiating light to display an image on the display area and a control unit which sequentially causes the plurality of light sources, which correspond to a plurality of areas divided from the display area, to emit light for each of the areas. The control unit repeatedly causes the light source, which corresponds to an area specified from the plurality of areas based on the image, to emit light during one frame period of displaying an image on the display area.

Embodiments will be described hereinafter with reference to the accompanying drawings.

Note that the disclosure is merely an example, and proper changes within the spirit of the invention, which are easily conceivable by a skilled person, are included in the scope of the invention as a matter of course. In addition, in some cases, in order to make the description clearer, the widths, thicknesses, shapes, etc., of the respective parts are schematically illustrated in the drawings, compared to the actual modes. However, the schematic illustration is merely an example, and adds no restrictions to the interpretation of the invention. Besides, in the specification and drawings, the same or similar elements as or to those described in connection with preceding drawings or those exhibiting similar functions are denoted by like reference numerals, and a detailed description thereof is omitted unless otherwise necessary.

FIG.1shows an example of the configuration of an image display system according to this embodiment. As shown inFIG.1, an image display system10includes a control device11and a display device12.

The control device11is equivalent to a host CPU or the like for controlling the operation of the image display system10, and supplies images and the like to be displayed on a display device12to the display device12, as will be described later.

The display device12is, for example, a liquid crystal display (LCD) including a display panel containing a liquid crystal layer, and displays images supplied from the control device11on a display area of the display panel.

Although omitted inFIG.1, it is assumed that the image display system10further includes, for example, a storage device that stores a program necessary for executing various types of processes in the image display system10, or other data, and the like.

In this embodiment, the control device11and the display device12are described as separate devices, but the control device11and display device12may be configured as a single unit.

FIG.2shows an example of the configuration of the display device12shown inFIG.1. As shown inFIG.2, the display device12includes a signal processing unit121, a display panel122, a panel drive unit (panel driver)123, a backlight (light source device)124and a backlight control unit (light source drive unit)125and the like.

The signal processing unit121is a processor which controls the operation of the display panel122and the backlight124. The signal processing unit121is connected to the panel drive unit121for driving the display panel122and the backlight control unit125for driving the backlight124.

Here, an image supplied from the control device11to the display device12contains a matrix of pixel data, which is referred to as a Bayer array, for example. Such an image is subjected to image processing (Bayer transformation) to be converted into an image signal containing RGB components. It is assumed that this image processing is performed, for example, in the control device11.

To the signal processing unit121, the image signal subjected to image processing as described above is input from the control device11. The signal processing unit121executes necessary processing on the input image signal and outputs to the panel drive unit123(display panel122).

Further, the signal processing unit121generates a backlight control signal based on the input image signal and outputs the backlight control signal to the backlight control unit125.

The display panel122includes a display area DA, and within the display area DA, a plurality of pixels PX are arranged in a two-dimensional matrix (of rows and columns).

The panel drive device123includes a signal output circuit123aand a scanning circuit123b. The signal output circuit123ais electrically connected to the display panel122by signal lines DTL. The signal output circuit123aholds the image signals output from the signal processing unit121and sequentially outputs the image signals to the display panel122.

The scanning circuit123bis electrically connected to the display panel122by scanning lines SCL. The scanning circuit123bcontrols switching elements for selecting pixels in the display panel122to be set to an on state or an off state.

The backlight124is disposed, for example, on a rear surface side of the display panel122and emits light toward the display panel122. The backlight124is provided with a plurality of light sources. As the light sources provided in the backlight, for example, light-emitting diode elements (to be simply referred to as “LEDs” hereinafter) are used.

The backlight control unit125adjust, for example, the current or duty cycle supplied to the backlight124based on the backlight control signal output from the signal processing unit121, thereby controlling the amount (intensity) of light irradiated from the backlight124to the display panel122.

The display device12with such a configuration displays images on the display area DA of the display panel122as the image signals (pixel signals) output from the signal processing unit121are sequentially written to each group of a plurality of pixels PX (display line) arrayed in matrix in the display panel122, which is illuminated by light from the backlight124, according to the operations of the panel drive device123(the signal output circuit123aand the scanning circuit123b) and the backlight control unit125.

Incidentally, the display device12(image display system10) of this embodiment can be used in a head-up display (HUD), in which images are reflected on a projection surface such as a windshield or the like of an automobile, to display the images in the driver's field of view. According to the head-up display, it is possible to reproduce virtual images in a location about 4 m ahead of the windshield, and the driver can view the images without greatly moving his/her line of sight.

Here, with reference toFIG.3, an outline of the head-up display will now be explained. As shown inFIG.3, the head-up display includes a display device12for projecting images and, for example, two concave mirrors M1 and M2. According to such a configuration, an image output from the display device12(that is, the image displayed in the display device12) is reflected and concentrated by the concave mirrors M1 and M2, and projected onto, for example, an inner surface (projection surface) of the windshield FG of an automobile.

The image thus projected is reflected by the windshield FG toward the driver and forms a virtual images V several meters ahead of the windshield FG.

Note here that the explanation is provided on the assumption that the mirrors M1 and M2, which constitute a part of the head-up display, are concave mirrors, but the mirrors M1 and M2 may not necessarily be concave mirrors, but may be other optical components such as half mirrors or Fresnel mirrors, for example. Further, the image may not be projected onto the windshield FG, but onto a transparent reflector or the like installed in front of the driver.

As described above, the images displayed on the display device12are supplied from the control device11, but the control device11is omitted from the illustration inFIG.3.

Here, it is assumed that in the display device12of this embodiment, backlight scan is employed as described above. The backlight scan is a method of dividing the display area DA (the light-emitting surface of the backlight124) into multiple areas and controlling the light emission of the backlight124so that the multiple areas are scanned sequentially. In other words, the backlight scan causes the backlight124to emit light by parts sequentially to correspond to each of the multiple areas divided from the display area DA. Such a backlight scan is useful for improving image quality.

The outline of the backlight scan will now be described with reference toFIG.4. Here, it is assumed that as shown inFIG.4, the display area DA is divided into multiple areas DA1to DA8. In the example shown inFIG.4, the display area DA is divided such that the multiple areas DA1to DA8each extend along the Y direction (the first direction) and the areas DA1to DA8are arranged along the X direction (the second direction).

Here, it is assumed that as shown inFIG.4, a plurality of LEDs124aare arranged in a matrix in the backlight124. Here, in the backlight scan, first, the LEDs124acorresponding to the area DA1(in this case, four LEDs124a) corresponding to area DA1are driven to emit light (lit). These LEDs124acorresponding to the area DA1are those LEDs disposed directly below the area DA1to illuminates the area DA1in order to display images in the area DAL Note that this is also the case for the LED124acorresponding to each of the other areas DA2to DA8.

Next, the light emission of the LEDs124acorresponding to the area DA1is stopped (the LEDs124aare set to the off state), and LED124bcorresponding to the area DA2are set to the on state. Then, similar control is repeated for from the area DA3on, and thus the backlight scan is executed.

Note thatFIG.5shows an example of the circuit configuration of the backlight124. As described above, in the backlight124, a plurality of LEDs124aare provided in a matrix. Further, to an anode of each of the four LEDs124acorresponding to the area DA1, for example, as described inFIG.4above, one end of a single common switch (anode switch)124bis electrically connected (anode common). On the other hand, cathodes of the four LEDs124acorresponding to the area DA1and the other end of the switch124bare electrically connected to the backlight control unit125. By setting the switch124bwith such a configuration to an on state and supplying anode power from the other end of the switch124b, the LED124acorresponding to the area DA1can be caused to emit light.

Here, the area DA1(corresponding to the multiple LEDs124a) is discussed above and the same can be applied to the other areas DA2to DA8. That is, in this embodiment, the switch124bis provided for each of the plurality of areas DA1to DA8divided from the display area. Here, when the switches124bare set into the on state sequentially, the backlight scan described above can be realized.

Note that in this embodiment, two switches124bare not set to the on state at the same time, but the switches124bare one by one set to the on state.

Note that inFIG.5, the numerals indicated near the switches124bindicate the order of the switches124bwhich are set to the on state. That is, in the backlight124shown inFIG.5, the switches124bare sequentially set to the on state in order from the left side in backlight scanning.

Incidentally, in general, the maximum luminance of the backlight124is limited by the instantaneous current that can flow to the LEDs124aprovided in the backlight124, but the instantaneous current is determined based on the rating (specification or performance) of the LEDs124a, the current supply capability of the backlight control unit125(LED driver), the power supply design or the like.

Therefore, in order to temporarily increase the brightness of the image displayed on the display device12employing the backlight scan described above, it is necessary to adjust the rating of the LEDs124aand design the backlight control unit125in accordance with the brightness to be increased, which increases the manufacturing cost of the display device12.

Therefore, the display device12of this embodiment has a configuration that can improve the brightness of the images without increasing the manufacturing cost.

The operation of the display device12of this embodiment will now be described with reference toFIGS.6to9.

First,FIG.6shows an example of an image displayed on the display device12, andFIG.7shows the timing for setting the on state in the switches124bprovided in each of the above-mentioned areas DA1to DA8when displaying an image200shown inFIG.6.

Assuming that the display device12of this embodiment is used for the head-up display described inFIG.3, the image200shown inFIG.6is equivalent to the image presented to the driver in a normal conditions, and the image200contains information such as the speed of the automobile driven by the driver, the legal speed of the road on which the automobile is traveling, and the like.

In the case where the LEDs124aare configured to emit light in units of the areas DA1to DA8as described above, it is necessary to drive the LEDs124ato emit light in all of the areas DA1to DA8for displaying the image200shown inFIG.6.

In this case, the backlight control unit125carry out control to emit light from the LEDs124acorresponding to each of the areas DA1to DA8by sequentially setting the on state in the switches124bprovided in each of the areas DA1to DA8as shown inFIG.7.

Note that the period from the start of light emission of the LEDs124acorresponding to the area DA1to the stop of light emission of the LEDs124acorresponding to the area DA8is equivalent to a period (one frame period) of displaying the image200(one frame). That is, to display the image200, during one frame period, each of the eight switches124bprovided for each of the areas DA1to DA8is set to the on state only one time during the one-frame period (that is, the backlight scan is executed once). Not that in this embodiment, such an expression as “backlight scan is executed once” is meant that all of the eight switches124bprovided for each of the areas subject to the backlight scan (in this case, the areas DA1to DA8) are set to the on state one time each.

Next,FIG.8shows another example of images displayed on the display device12, andFIG.9shows the timing for setting the on state in the switches124bprovided in each of the above-mentioned areas DA1to DA8when displaying an image300shown inFIG.8.

Assuming that the display device12of this embodiment is used for the head-up display described inFIG.3, the image300shown inFIG.8is equivalent to an image presented to the driver in an emergency, and the image300contains information that notifies that, for example, the road on which the automobile driven by the driver is running is slippery. The image300includes information that notifies the driver that, for example, the road on which the driver's vehicle is traveling is slippery.

In the case where the LEDs124aare configured to emit light in units of the areas DA1to DA8as described above, it suffices if the LEDs124aare driven to emit light in each of the areas DA3to DA6out of the areas DA1to DA8in order to display the image300shown inFIG.8. In other words, in the image300, left and right regions which have a certain width in the image300(specifically, the areas DA1, DA2, DA7and DA8) are black areas, where illumination from the backlight124is not required.

In this case, the backlight control unit125sets the switch124bprovided for each of the areas DA3to DA6to the on state, sequentially as shown inFIG.9, so as to drive the LEDs24corresponding to each of the areas DA3to DA6to sequentially emit light.

Here, when displaying the image200described above, the eight LEDs provided for each of the areas DA1to DA8are set to the on state one by one during one frame period. On the other hand, when displaying image300, the eight switches124bprovided for each of the areas DA3to DA6(the areas subjected to backlight scan) are set to the on state twice each as shown inFIG.9(in other words, the backlight scan is executed twice).

That is, in this embodiment, no an image such as the image200, for which all of the LEDs124acorresponding to the entire display area DA (the areas DA1to DA8) need to be driven to emit light (lit) (full screen illuminated image), but an image such as the image300, which can be display by driving only the LED124acorresponding to a part of the display area DA (the areas DA1to DA8) (partially illuminated image) is to be displayed, only the corresponding LEDs124ashould be driven to emit light repeatedly during one frame period.

Note that the image to be displayed on the display device12in this embodiment is supplied to the display device12from the control device11, but the image (for example, the image200or300) may be determined by the control device11based on, for example, information held within the image display system10or information obtained from outside the image display system10(for example, a server equipment or various types of sensors, etc.).

Further, the area where the LEDs124aare needed to emit light in order to display the image supplied from the control device11as described above, may be specified, for example, by the control device11side based on the corresponding image and instructed (notified) to the display device12. Or the area may be specified by the display device12side (for example, the signal processing unit121or the like) based on the corresponding image.

This embodiment is described in connection with the case where the LEDs124acorresponding to the areas DA3to DA6are repeatedly driven to emit light during one frame period (that is, the backlight scan is repeated for the areas DA3to DA6), but the areas corresponding to the LEDs124awhich are driven to emit light repeatedly are not necessarily contiguous with each other.

Specifically, when displaying, for example, an image400shown inFIG.10as the partially illuminated image described above, the LEDs124acorresponding to each of the areas DA1, DA2, DA7and DA8among the areas DA1to DA8should be driven to emit light sequentially.

In this case, the backlight control unit125sets the LEDs124acorresponding to the areas DA1, DA2, DA7, and DA8to the on state sequentially as shown inFIG.11, and thus the LEDs124acorresponding to each of the areas DA1, DA2, DA7and DA8are driven to emit light repeatedly emitted during one frame period.

The areas DA1to DA8described in this embodiment are an example, and the number of areas divided from the display area may be other than eight, and the shape of the areas may as well be different from that described in this embodiment. Further, this embodiment is described in connection with the case where the number of LEDs124acorresponding to each of the areas DA1to DA8is four, but the number of LEDs124acorresponding to each of the areas DA1to DA8may be other than four, and the arrangement of the LEDs may as well be different from that described in this embodiment. Further, for example,FIG.9and the like show an example case where the backlight scan is repeated twice, and one frame period ends at the timing when the switches124bprovided for the area DA6are switched from the on state to the off state. But, depending on the period during which the on state of each of the switched124bis maintained, the light emission of the backlight124(the LEDs124a) may be controlled so that one frame period ends at the timing when the switches124bprovided for, for example, the areas other than the area DA6(that is, the areas DA3to DA5) are switched from the on state to the off state. That is, in this embodiment, it suffices if the LEDs124acorresponding to at least one of the areas specified by the image (for example, the areas DA3to DA6) are configured to emit light multiple times during one frame period.

As described above, in this embodiment, when the backlight scan in which the LEDs (light sources)124acorresponding to each of the plurality of areas (for example, the areas DA1to DA8) divided from the display area DA is employed, the LEDs124acorresponding to those of the areas specified based on the image (in other words, the LEDs124athat need to be driven to emit light when displaying an image) are driven to emit light repeatedly during one frame period when the image is displayed in the respective display area DA.

In other words, in this embodiment, when the area in which the LEDs124aare driven to emit light can be reduced according to the image to be displayed (that is, displaying a partially illuminated image), the number of backlight scans per unit time (one frame period) is increased, and thus the light emission time of the LEDs124acorresponding to the area subjected to the backlight scans can be reduced. Thus, in this embodiment, the brightness of the image displayed on the display device12can be improved.

Specifically, in the case of the configuration in which the backlight scan is repeated for four (the areas DA3to DA6or the like) of the eight areas DA1to DA8divided from the display area DA as described above, the LEDs124aare caused to emit light twice the number of times (that is, twice the period) for one area, as compared to the configuration in which the backlight scan is executed for all of the areas DA1to DA8as described inFIG.7, thereby increasing the brightness of the image two times.

In addition, although specific examples of images are omitted, in the case of the configuration in which the backlight scan is repeated for two areas DA4and DA5of the areas DA1to DA8as shown inFIG.12, for example, the LEDs124aare caused to emit light four times the number of times (that is, four times the period) for one area, as compared to the configuration in which the backlight scan is repeated for all of the areas DA1to DA8, thereby increasing the brightness of the image four times.

In other words, when displaying an image (partially illuminated image) in which the area (illuminated area) in which the LEDs124aare emitted is ½ or ¼ of the display area DA, the maximum brightness of the image is can be made two or four times that of the normal image (full screen illuminated image).

According to the above configuration, the brightness of the images can be improved without changing, for example, the ratings of LEDs124a, the design of the backlight control unit (LED driver) and the power source and the like, and therefore, the increase in manufacturing cost can be suppressed.

Further, in this embodiment, for example, the image200(a first image) displayed in a normal situation and the image30and the image300(a second image) displayed in an emergency situation can be displayed, and the area specified based on the image200is different from the area specified based on the image301. That is, in this embodiment, when displaying a full-screen illuminated image such as the image200and a partially illuminated image such as the image300while switching therebetween, the brightness of the partially illuminated image can be improved when the image is displayed.

In this embodiment, the LEDs124aare arranged in a matrix, and the areas DA1to DA8divided from the display area DA each extend along the Y direction (the first direction) and are aligned along the X direction (the second direction). Furthermore, the LEDs124acorresponding to each of the areas DA1to DA8with such a configuration are electrically connected to the switches124bprovided for the area. In this embodiment, by sequentially setting the switches124bwith such a configuration to the on state, the backlight scan can be executed.

Note that this embodiment is described on the assumption that the corresponding LEDs124aare caused to emit light in the order of the areas DA1to DA8as described with reference toFIG.5, but, for example, depending on the specifications or performance of the backlight control unit125, the switch124b(LED124a) that initiates the backlight scan may have to be fixed. In this case, for example, assuming that the switches124bare set to the on state in the order described with reference toFIG.5, the switches124bmust be set to the on state from those provided for the area DA1, and therefore the image200and the like cannot be displayed as described in this embodiment.

In contrast, for example, even in the case where the order in which the switches124bdescribed with reference toFIG.5, for example, are set to the on state is changed as shown inFIG.13, the image200and the like can be displayed at high brightness if the switch124bthat starts the backlight scan as described above needs to be fixed as described above. That is, in this embodiment, it suffices if the switches124bare configured to be set to the on state in a predetermined order based on the image to be displayed on the display device12.

Further, in this embodiment, the brightness of the image displayed on the display device12is improved as described above, and therefore, for example, the visibility of the image displayed in an emergency situation, such as the image300can be improved. Thus, it is possible to promote alertness based on the information to be notified in such an emergency situation. But, from the viewpoint of promoting such alertness, such display control may be performed that the image300and the image400, which can be displayed with high brightness, are periodically switched (that is, blinking by alternately displaying), as shown inFIG.14.

Further, in such a case where the display device12is used for a head-up display, the brightness of the backlight124(the LEDs124a) when the image200is displayed in a normal situation may be adjusted according to the illuminance (brightness) of the external light measured by a sensor, for example. Even in such a configuration, when displaying the image300and the like in an emergency situation, as described above, the backlight124is automatically caused to emit light at the maximum brightness (that is, the current of the backlight control unit125is automatically set to the maximum), thereby further improving the visibility.

Note that the descriptions are directed to the case where the backlight124is caused to emit light at the maximum luminance, the backlight124(the LEDs124a) may not necessarily be caused to emit light at the maximum luminance, or the luminance of the backlight124may be changed at the timing when the backlight scan is repeated during one frame period. According to such a configuration, while improving the brightness of the image, the power saving can be achieved.

Furthermore, in this embodiment, the LEDs124aprovide in the backlight124are driven by a passive matrix mode, for example, but if the light emission (lighting) time of the LEDs124ais limited to a part of one frame period, this embodiment may be applied to the display device12in which the LEDs124aare driven by the active matrix mode.

Incidentally, this embodiment is described on the assumption that the display device12includes one backlight control unit125. But, as shown inFIG.15, the display device12may be configured to include two backlight control units (a first backlight control unit125aand a second backlight control unit125b) as shown inFIG.15(to be referred to as a modified example hereinafter).

FIG.16shows an example of the circuit configuration of the backlight124provided in the display device12of this modified example.

This modified example is different from that shown inFIG.5in that the first backlight control unit125ais connected to some of the LEDs124provided in a matrix in the backlight124, and the second backlight control unit125bis connected to the remaining ones (the second light source) of the LEDs124a.

In the example shown inFIG.16, the first backlight control unit125ais electrically connected to the LEDs124acorresponding to the areas DA1to DA4of the areas DA1to DA8divided from the display area DA.

On the other hand, the second backlight control unit125bis electrically connected to the LEDs124acorresponding to the areas DA5to DA8of the areas DA1to DA8divided from the display area DA.

Note that the configuration in which the switches124bare provided for each of the areas DA1to DA8is as described with reference toFIG.5provided above, and therefore detailed descriptions thereof will be omitted here.

According to this configuration, the first backlight control unit125asequentially sets the switches124bprovided for the areas DA1to DA4, and thus the LEDs124acorresponding to each of the areas DA1to DA4can be caused to emit light sequentially for each of these areas. Similarly, the second backlight control unit125bsequentially set the switches124bprovided for the areas DA5to DA8to the on state, and thus the LEDs124bcorresponding to the areas DA5to DA8can be sequentially caused to emit light for each of the areas.

In the case of such a configuration which includes the first backlight control unit125aand the second backlight control unit125bas in this modified example, two switches124bcan be set to the on state at the same time.

The operation of the display device12in this modified example will now be described with reference toFIGS.17and18.

First,FIG.17shows the timing of setting the switches124bprovided for each of the areas DA1to DA8to the on state when displaying the image200shown inFIG.6discussed above.

In order to display the image200shown inFIG.6, the LEDs124amust be caused to emit light in all of the areas DA1to DA8.

In this case, the first backlight control unit125asequentially set the LEDs124aprovided for each of the areas DA1to DA4to the on state, and thus the LEDs124acorresponding to each of the areas DA1to DA3are sequentially caused to emit light.

Note that the period from the start of the light emission of the LEDs124acorresponding to area DA1to the stop of the light emission of the LEDs124bcorresponding to the area DA4is equivalent to the period (one frame period) during which image200is displayed. That is, when displaying the image200in this modified example, each of the switches124bprovided for each of the areas DA1to DA4is set to on state just once during one frame period (that is, the backlight scan is executed once).

Similarly, the second backlight control unit125bsequentially sets the switches provided for each of the areas DA5to DA8to the on state, and thus the LEDs124acorresponding to each of the areas DA5to DA8are sequentially caused to emit light.

Note that the period from the start of light emission of the LEDs124acorresponding to the area DA5to the stop of light emission of the LEDs124acorresponding to the area DA8is equivalent to the period during which the image200is displayed (one frame period). That is, when displaying the image200in this modified example, each of the switches124bprovided for each of the areas DA5to DA8is set to the on state just once during one frame period (that is, the backlight scan is executed once).

Thus, in this modified example, the LEDs124acorresponding to two of the areas DA1to DA8are caused to emit light at the same time, and thus the light emission time of each of these LEDs124acan be prolonged. Therefore, the luminance can be increased as compared to the case described with reference toFIG.7provided above.

Next,FIG.18shows the timing of setting the switches124bprovided for each of the areas DA1to DA8to the on state when displaying the image300shown inFIG.8provided above.

In order to display the image300shown inFIG.8, it suffices if the LEDs124aare caused to emit light in the areas DA3to DA6of the areas DA1to DA8as described above.

In this case, the first backlight control unit125asequentially set the switches124bprovided for each of the areas DA3and DA4to the on state as shown inFIG.18, and thus the LEDs124acorresponding to each of the areas DA3and DA6are sequentially caused to emit light.

Similarly, the second backlight control unit125bsequentially sets the switches124bprovided for each of the areas DA5and DA6to the on state, and thus the LEDs124bprovided for each of the areas DA5and DA6are sequentially caused to emit light.

Here, when displaying the image200described above, the four LEDs124aprovided for each of the areas DA1to DA4are set to the on state one time each during one during one frame. On the other hand, when displaying the image300, each of the two switches124bprovided for each of the areas DA3and DA4can be set to the one state twice each (that is, the backlight scan is executed twice), and further each of the two switches124bprovided for each of areas DA5and DA6can be set to the one state twice each (that is, the backlight scan is executed twice), as shown inFIG.18.

That is, this modified example includes the first backlight control unit125aand the second backlight control unit125b. The first backlight control unit125arepeatedly causes those corresponding to the areas DA3and DA4of the LEDs124acorresponding to the areas (for example, the areas DA3to DA6) specified based on an image to emit light, whereas the second backlight control unit125brepeatedly causes those corresponding to the areas DA5and DA6of the LEDs124acorresponding to the areas (for example, the areas DA3to DA6) specified based on the image to emit light.

In this modified example, with such a configuration as described above, the number of times of backlight scans per unit time (one frame period) can be increased, and thus the brightness of the image displayed on the display device12can be improved.

Specifically, in the case of the configuration that the backlight scan is repeated for four of the multiple areas DA1to DA8divided from the display area DA, the LEDs124aare caused to emit light twice the number of times (that is, twice the period) for one area as compared with the configuration in which the backlight scan is repeated for all of the areas DA1to DA8as described with reference toFIG.17, thereby making the brightness of the image two times as high.

That is, even in the case of the configuration including two backlight control units as in this modified example, when the area in which the LEDs124aare caused to emit light (lit area) displays an image (partially illuminated image) of ½ of the display area DA, the maximum brightness of the image can be made twice that of the image (full screen image) in a normal situation. Although the details thereof are omitted, in the case of displaying an image in which the area in which the LED124aemits light is ¼ of the display area DA, the maximum brightness of the image can be made four times that of the image in the normal situation.

Note that this embodiment (and the modified example of this embodiment) described above is described in connection with the backlight124(direct type LED backlight) in which LEDs are disposed at positions corresponding to the entire surface of the display panel122(that is, directly below the display panel12), but the backlight124may be an edge type LED backlight in which LEDs are arranged at positions corresponding to the left, right, upper, lower and other edges of the display panel122.

Further, when the display device12of this embodiment is a liquid crystal display as described above, the display device12may as well be configured to carry out local dimming to control the luminance distribution of the backlight124according to the image. In other words, this embodiment can be used in conjunction with local dimming.

Furthermore, the display device12of this embodiment may be, for example, an LED display in which a plurality of light-emitting diode elements (light sources) are arranged according to a plurality of pixels, or may be, for example, an OLED display in which a plurality of organic electroluminescent elements (light sources) are arranged according to a plurality of pixels.

Inventions according to this embodiment are added as appendix.

[C1]

A display device including:a display panel including a display area whichdisplays images;a plurality of light sources irradiating light to display an image on the display area; anda control unit which sequentially causes the plurality of light sources, which correspond to a plurality of areas divided from the display area, to emit light for each of the areas, whereinthe control unit repeatedly causes the light source, which corresponds to an area specified from the plurality of areas based on the image, to emit light during one frame period of displaying an image on the display area.
[C2]

The display device of item [C1], whereinthe image displayed on the display area includes a first image and a second image, andan area specified based on the first image is different from an area specified based on the second image.
[C3]

The display device of item [C1] or [C2], whereinthe plurality of light sources are arranged in a matrix along a first direction and a second direction; andthe plurality of areas extend along the first direction and are aligned along the second direction.
[C4]

The display device of item [C3], further including:a plurality of switches provided for the plurality of areas,whereinthe light source corresponding to each of the plurality of areas is electrically connected to the switch provided for the area, respectively.
[C5]

The display device of item [C4], whereinthe plurality of switches are configured to be set to on state in a predetermined order based on the image.
[C6]

The display device of any one of items [C1] to [C5], whereinthe control unit includes a first control unit which causes a first light source of the plurality of light sources to emit light and a second control unit which causes a second light source different from the first light source of the plurality of light sources to emit light,the first control unit repeatedly causes the first light source which corresponds to the area specified based on the image to emit light during one frame period in which the image is displayed on the display area, andthe second control unit repeatedly causes the second light source which corresponds to the area specified based on the image during to emit light one frame period in which the image is displayed on the display area.
[C7]

The display device of any one of items [C1] to [C6], whereinthe display panel includes a liquid crystal layer, andthe plurality of light sources are provided in a backlight disposed on a rear surface side of the display panel.
[C8]

The display device of any one of [C1] to [C6], whereinthe display panel includes a plurality of pixels arranged in a matrix in the display area, andthe plurality of light sources includes a plurality of light-emitting diode elements provided in accordance with the plurality of pixels.
[C9]

The display device of any one of [C1] to [C6], whereinthe display panel includes a plurality of pixels arranged in a matrix in the display area, andthe plurality of light sources include a plurality of organic electroluminescent elements provided in accordance with the plurality of pixels.
[C10]

A method executed by a display device including a display panel including a display area which displays images and a plurality of light sources irradiating light to display an image on the display area, the method including:when sequentially causing the plurality of light sources, which correspond to the plurality of areas divided from the display area, to emit light for each of the areas, repeatedly causing the light source, which corresponds to an area specified from the plurality of areas based on the image, to emit light during one frame period in which an image is displayed in the display area.
[C11]

The method of item [C10], whereinthe image displayed on the display area includes a first image and a second image, andan area specified based on the first image is different from an area specified based on the second image.
[C12]

The method of item [C10] or [C11], whereinthe plurality of light sources are arranged in a matrix along a first direction and a second direction; andthe plurality of areas extend along the first direction and are aligned along the second direction.
[C13]

The method device of item [C12], whereinthe display device further includes a plurality of switches provided for the plurality of areas,andthe light source corresponding to each of the plurality of areas is electrically connected to the switch provided for the area, respectively.
[C14]

The method of item [C13], whereinthe plurality of switches are configured to be set to one state in a predetermined order based on the image.
[C15]

The method of any one of items [C10] to [C14], whereinthe repeatedly causing the light sources to emit light, includes causing a first light source of the plurality of light sources to emit light and causing a second light source different from the first light source of the plurality of light sources to emit light,the causing the first light source to emit light, includes repeatedly causing the first light source which corresponds to the area specified based on the image to emit light during one frame period in which the image is displayed on the display area, andthe causing the second light source to emit light, includes repeatedly causing the second light source which corresponds to the area specified based on the image to emit light during one frame period in which the image is displayed on the display area.
[C16]

The method of any one of items [C10] to [C15], whereinthe display panel includes a liquid crystal layer, andthe plurality of light sources are provided in a backlight disposed on a rear surface side of the display panel.
[C17]

The method of any one of items [C10] to [C15], whereinthe display panel includes a plurality of pixels arranged in a matrix in the display area, andthe plurality of light sources includes a plurality of light-emitting diode elements provided in accordance with the plurality of pixels.
[C18]

The method of any one of [C10] to [C15], whereinthe display panel includes a plurality of pixels arranged in a matrix in the display area, andthe plurality of light sources include a plurality of organic electroluminescent elements provided in accordance with the plurality of pixels.

All display devices, which are implementable with arbitrary changes in design by a person of ordinary skill in the art based on the display devices described above as the embodiments of the present invention, belong to the scope of the present invention as long as they encompass the spirit of the present invention.

Various modifications are easily conceivable within the category of the idea of the present invention by a person of ordinary skill in the art, and these modifications are also considered to belong to the scope of the present invention. For example, additions, deletions or changes in design of the constituent elements or additions, omissions or changes in condition of the processes may be arbitrarily made to the above embodiments by a person of ordinary skill in the art, and these modifications also fall within the scope of the present invention as long as they encompass the spirit of the present invention.

In addition, the other advantages of the aspects described in the above embodiments, which are obvious from the descriptions of the specification or which are arbitrarily conceivable by a person of ordinary skill in the art, are considered to be achievable by the present invention as a matter of course.