JP2007225871A - Display device and its display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device and its display method in which the device reduces power consumption at the time of displaying a bright video and eliminates luminance unevenness at the time of displaying a dark video. <P>SOLUTION: In the display device for displaying video information, first light emitting diodes (LEDs 1) of strong irradiation light and second light emitting diodes (LEDs 3) of weak irradiation light are alternately arranged and the average luminance value within one screen of the video information is computed and whether the average luminance value is above the prescribed value or not is decided. If the average luminance value is above the prescribed value, only the LEDs 1 are made to emit light and if the average luminance value is below the prescribed value, the LEDs 1 and the LEDs 3 are made to emit light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device and a display method thereof, and more particularly to a display device that displays video information and a display method thereof.

  In recent years, liquid crystal display devices (LCDs) have been widely used as display devices for electronic devices such as personal computers, mobile phones, and navigation systems. A liquid crystal display device applied to such an electronic device generally has a configuration in which an illumination device (backlight) is provided on the back side of a transmissive display panel, and the display panel on which video information is displayed is applied. Visibility is improved by irradiating irradiation light.

10A and 10B are schematic views of a conventional backlight, in which FIG. 10A is a simplified configuration diagram of the backlight, and FIG. 10B is a diagram of the backlight viewed from the direction of the upper surface of the light guide plate. Although not shown, an LCD is disposed on the upper surface side of the light guide plate.
As shown in FIG. 10A, the backlight includes a light source in which a plurality of white light emitting diodes (LEDs) 50 are arranged, a light guide plate 52, and the like. In the backlight, the light emitted from the LED 50 enters the inside from the side surface 54 of the light guide plate and is emitted through the upper surface 56 of the light guide plate, thereby converting the light into planar light and irradiating the LCD. In such a backlight, the luminance uniformity is required. However, as shown in FIG. 10B, in the vicinity of the light source 58, the light from the light source does not reach and causes luminance unevenness. It was. Further, since all the LEDs 50 of the light source emit light when displaying an image, the power consumption of the backlight is large.

As a first conventional technique, as shown in FIG. 11, a backlight is proposed that includes a light source in which wide directional LEDs 60 and narrow directional LEDs 62 are alternately arranged, and these lights are incident on a light guide plate 64 ( Patent Document 1). According to this technology, the light of the narrow directivity angle LED 62 reaches the vicinity 66 near the light source, and the luminance unevenness near the light source 66 can be eliminated. As a second conventional technique, a backlight that changes the illuminance of irradiation light emitted from the backlight when displaying a special image (for example, an image having a letterbox) as shown in FIG. 12 has been proposed. (See Patent Document 2). Specifically, the presence / absence of a letterbox is detected from the video, the illuminance of the LEDs 7 and 12 corresponding to the letterbox is reduced, and the illuminance of the LEDs 8 to 11 corresponding to the video area is normal. According to this technique, the power consumption of the backlight can be reduced.
JP 2004-303578 A JP 2004-221503 A

  However, although the first conventional technique can eliminate luminance unevenness near the light source, even when displaying an image in which the luminance unevenness is difficult to recognize (for example, a bright image with a high luminance value), all the wide directivity LEDs are narrow. Since the directional angle LED emits light, the power consumption of the backlight has increased. In the second prior art, although the power consumption can be reduced by controlling the intensity of the irradiation light of each LED, the luminance unevenness in the vicinity of the light source cannot be eliminated.

  Accordingly, an object of the present invention is to provide a display device and a display method for reducing power consumption when displaying a bright image and eliminating luminance unevenness when displaying a dark image.

  According to the present invention, in the display device that displays video information, the above-described problem is an average luminance value calculation unit that calculates an average luminance value in one screen of the video information, a first light-emitting diode that emits strong light, It is determined whether the backlight unit alternately arranged with the second light emitting diodes having weak irradiation light and the average luminance value calculated by the average luminance value calculating unit are equal to or greater than a predetermined value, and the average luminance value is a predetermined value If so, the first light emitting diode is instructed to emit light, and if the average luminance value is less than a predetermined value, the first light emitting diode and the second light emitting diode emit light. This is achieved by a display device that includes an instruction control unit and a light emission adjustment unit that adjusts a light emission state of the first light emitting diode and the second light emitting diode based on an instruction from the control unit.

  According to the present invention, in the display device that displays video information, the non-display area detection unit that detects a non-display area included in the video information, the first light-emitting diode with strong irradiation light, and the irradiation light And when the non-display area is detected by the non-display area detecting section, the first light-emitting diode and the second light-emitting diode emit light. And when the non-display area is not detected, a control unit that instructs to emit light from the first light emitting diode, and the first light emitting diode and the first light emitting diode based on the instruction from the control unit This is achieved by a display device that includes a light emission adjusting unit that adjusts a light emission state with the two light emitting diodes.

  The control unit instructs the first light emitting diode and the second light emitting diode to emit light in a region corresponding to the non-display region, and turns the first light emitting diode in a region not corresponding to the non-display region. Instruct to emit light.

  According to the present invention, in the display method of a display device for displaying video information, the first light emitting diode with strong irradiation light and the second light emitting diode with low irradiation light are alternately arranged, and the video is displayed. An average luminance value in one screen of information is calculated, it is determined whether the average luminance value is a predetermined value or more, and if the average luminance value is a predetermined value or more, the first light emitting diode is emitted, If the average luminance value is less than a predetermined value, it is achieved by the display method of the display device that emits light from the first light emitting diode and the second light emitting diode.

  According to the present invention, in the display method of a display device for displaying video information, the first light emitting diode with strong irradiation light and the second light emitting diode with low irradiation light are alternately arranged, and the video is displayed. When a non-display area included in information is detected and the non-display area is detected, the first light-emitting diode and the second light-emitting diode emit light, and when the non-display area is not detected, This is achieved by a display method of a display device that emits light from one light emitting diode.

  According to the present invention, when the non-display area is detected, the first light-emitting diode and the second light-emitting diode emit light in the area corresponding to the non-display area, and the non-display area is detected. In the non-corresponding region, the first light emitting diode emits light.

  According to the present invention, first light emitting diodes with strong irradiation light and second light emitting diodes with low irradiation light are alternately arranged to calculate an average luminance value within one screen of the video information, and the average It is determined whether the luminance value is equal to or higher than a predetermined value. If the average luminance value is equal to or higher than the predetermined value, the first light emitting diode emits light. If the average luminance value is lower than the predetermined value, the first Since the light emitting diode and the second light emitting diode are configured to emit light, power consumption is reduced when displaying a bright image in which luminance unevenness is difficult to recognize, and luminance unevenness is displayed when displaying a dark image in which luminance unevenness is easily recognized. Can be eliminated.

  According to the present invention, the first light emitting diodes with strong irradiation light and the second light emitting diodes with low irradiation light are alternately arranged to detect a non-display area included in the video information, and the non-display area If the first light emitting diode is detected, the first light emitting diode and the second light emitting diode emit light. If the non-display area is not detected, only the first light emitting diode emits light. Luminance unevenness can be eliminated for an image including a region. In addition, for an image that does not include a non-display area, power consumption can be reduced because only the first light emitting diode needs to emit light.

  According to the present invention, when the non-display area is detected, the first light emitting diode and the second light emitting diode emit light in the area corresponding to the non-display area, and the area does not correspond to the non-display area. Then, since the first light-emitting diode is configured to emit light only, luminance unevenness can be eliminated in the non-display area, and power consumption can be reduced in the non-display area.

(A) Outline of the Present Invention FIG. 1 is a schematic view of the present invention.
In the display device, a light source is configured by alternately arranging LEDs 1 having strong irradiation light and LEDs 3 having low irradiation light. The display device receives a video signal from a video player such as a DVD player, calculates an average luminance value from the video signal, and determines whether the average luminance value is a predetermined value or more. If this average luminance value is equal to or greater than a predetermined value, the display device determines that the image is a bright image in which uneven luminance is difficult to recognize, emits only the LED 1 with strong irradiation light, and is not shown through the light guide plate 5. The LCD is irradiated (see FIG. 1A). On the other hand, if the average luminance value is not equal to or greater than the predetermined value, the display device determines that the image is a dark image in which uneven brightness is easily recognized, and emits the LED 1 with strong irradiation light and the LED 3 with low irradiation light, An LCD (not shown) is irradiated through the light guide plate 5 (see FIG. 1B). Accordingly, it is possible to reduce power consumption when displaying a bright video in which luminance unevenness is difficult to recognize, and to eliminate luminance unevenness when displaying a dark image in which luminance unevenness is easily recognized.

(B) Configuration of Backlight in the Present Invention FIG. 2 is an exploded view for explaining the configuration of the backlight that irradiates the LCD.
As shown in FIG. 2, the backlight is roughly configured to include a flat light source unit 10 and a light emission adjusting unit 12.
The planar light source unit 10 has a planar shape corresponding to the shape of the LCD 14, and includes a light guide plate 10a, a reflection plate 10b disposed on the bottom surface side of the light guide plate 10a (the side opposite to the LCD 14 side), and an upper surface side of the light guide plate 10a. A diffusion plate 10c disposed on the (LCD 14 side) and a light source 10d in which LEDs 1 with strong irradiation light and LEDs 3 with low irradiation light are alternately arranged along the side surface of the light guide plate 10a are provided. In such a planar light source unit 10, the light emitted from the light source unit 10 d is incident on the side surface of the light guide plate 10 a, is repeatedly reflected, and is emitted through the diffuser plate 10 c, so that the light is emitted from the back side of the LCD 14. Irradiate.
The light emission adjusting unit 12 is configured to control the LEDs 1 and 3 constituting the light source unit 10d based on a light emission control signal from a control unit (not shown). Here, in the light emission control of the LED 1 and the LED 3 by the light emission adjusting unit 12, when a bright image is displayed on the LCD 14, only the LED 1 constituting the light source unit 10 d is caused to emit light and the LCD 14 is irradiated with irradiation light. Further, when a dark image is displayed on the LCD 14, the LED 1 and the LED 3 constituting the light source unit 10d are caused to emit light and the LCD 14 is irradiated with irradiation light.

FIG. 3 is a circuit diagram showing a circuit example of the backlight according to the present invention.
The LED 1 with strong irradiation light and the LED 3 with low irradiation light are alternately arranged, and the anode terminals are connected in parallel at a common contact point Na to constitute the light source unit 10d (here, both LED 1 and LED 3 are 3 for convenience). Is shown). The cathode terminal of each LED 1 is connected to a resistor R1 connected to the ground potential via a common contact Nb. The cathode terminal of each LED 3 is connected to one end of a switch SW (light emission adjusting unit 12), and the other end of the switch SW is connected to a resistor R3 connected to the ground potential via a common contact Nb. However, the resistance value of the resistor R1 connected to the LED1 is smaller than the resistance value of the resistor R3 connected to the LED3. As a result, a larger current than LED 3 flows through LED 1, and LED 1 with strong irradiation light and LED 3 with low irradiation light can be realized. The drive power supply BT has a positive electrode connected to the contact Na and a negative electrode connected to the ground potential.
Based on the light emission control signal from the control unit 16, the light emission adjustment unit 12 switches the switch SW between on and off. Specifically, the video processing unit 14 calculates an average luminance value in one screen from the video signal, and inputs this average luminance value to the control unit 16. The control unit 16 determines whether the average luminance value is equal to or greater than a predetermined value. If the average luminance value is equal to or greater than the predetermined value, the control unit 16 determines that the image is a bright image in which uneven luminance is difficult to recognize, and only the LED 1 is used. If the average luminance value is not equal to or greater than a predetermined value, it is determined that the image is a dark image in which uneven luminance is easily recognized, and the LEDs 1 and 3 are emitted. The light emission adjusting unit 12 is instructed. Thus, based on this instruction, the light emission adjusting unit 12 turns off the switch SW and causes the LED 3 not to emit light if the image is bright, and turns on the switch SW and turns on the LED 3 if the image is dark. Make it emit light.

(C) Configuration of Display Device in Present Invention FIG. 4 is a configuration diagram of a display device in the present invention, and the backlight uses the backlight shown in FIG.
A video signal from a video player such as a DVD player (not shown) is input to the video holding unit 20 and the video processing unit 22. The video processing unit 22 calculates an average luminance value in one screen from the video signal, inputs the average luminance value to the control unit 24, and instructs the timing signal generation unit 26 that the average luminance value calculation processing is completed. To do. Based on this instruction, the timing signal generator 26 generates a timing signal and inputs this signal to the controller 24. The control unit 24 determines whether the average luminance value from the video processing unit 22 is a predetermined value or more. If the average luminance value is equal to or greater than a predetermined value, the backlight unit 30 is instructed to emit only LEDs with strong irradiation light. If the average luminance value is not equal to or greater than the predetermined value, all LEDs are emitted. Instructs the backlight unit 30. Thereby, the backlight part 30 performs light emission adjustment of LED for every screen display. Further, the control unit 24 generates control signals (horizontal control signal, vertical control signal) for controlling the operation timing in the source driver 28 and the gate driver 32 based on the timing signal from the timing signal generation unit 26, and the horizontal control signal Is output to the source driver 28, and the vertical control signal is output to the gate driver 32. Based on the horizontal control signal from the control unit 24, the source driver 28 sequentially captures and holds video signals for one row of the LCD 34 from the video holding unit 20. On the other hand, the gate driver 32 sequentially applies scanning signals to the scanning lines SL arranged on the LCD 34 based on the vertical control signal from the control unit 24 to set the display pixels Px group in each row to a selected state. The source driver 28 supplies the video signal voltage corresponding to the held video signal to each display pixel Px simultaneously through each data line DL in synchronization with the selection timing of the display pixel Px group in each row. By repeating such a series of operations for each row for one screen, desired video information based on the video signal is displayed on the LCD 34. At this time, the video information is viewed by the user by causing the backlight to emit light in synchronization with the display timing of the video information for one screen and transmitting the irradiation light from the backlight unit 30 to the viewing side of the LCD 34. The

(D) First light emission adjustment processing in the present invention In the first light emission adjustment processing in the present invention, an average luminance value in one screen of video information is calculated, and light emission of the backlight is adjusted according to this average luminance value. To do.
FIG. 5 is a flowchart showing the first light emission adjustment processing in the present invention.
A video signal for one screen is input to the video holding unit 20 and the video processing unit 22 from a video player (not shown) (step S1). The video processing unit 22 calculates an average luminance value from the video signal, and inputs this average luminance value to the control unit 24 (step S2). The control unit 24 determines whether the average luminance value is equal to or greater than a predetermined value Th (step S3). If the average luminance value is equal to or greater than the predetermined value Th, the control unit 24 recognizes the image as a bright image, instructs the backlight unit 30 to emit only the LED with strong irradiation light, and the backlight unit. The light emission adjusting unit 12 (FIG. 3) 30 turns off the switch SW and causes only the LED 1 with strong irradiation light to emit light (step S4). Accordingly, when a bright image is input, the backlight unit 30 operates as shown in FIG. On the other hand, if the average luminance value is not equal to or greater than the predetermined value Th, the control unit 24 recognizes the image as a dark image, instructs the backlight unit 30 to emit all LEDs, and the backlight unit 30. The light emission adjusting unit 12 turns on the switch SW, and causes all the LEDs (the LED 1 with strong irradiation light and the LED 3 with low irradiation light) to emit light (step S5). Thereby, when a bright image is input, the backlight unit 30 operates as shown in FIG. Thereafter, it is determined whether there is a video signal for one screen from the video player (step S6). If there is no video signal for one screen from the video player, the light emission adjustment process is terminated, and one screen from the video player. If there are enough video signals, the processes in steps S1 to S5 are repeated.

  According to the first light emission adjustment process, an average luminance value within one screen of video information is calculated, it is determined whether the average luminance value is equal to or greater than a predetermined value, and if the average luminance value is equal to or greater than a predetermined value. If only the LED with strong irradiation light is emitted and all the LEDs emit light if the average luminance value is less than the predetermined value, the power consumption is reduced when displaying a bright image in which uneven luminance is difficult to recognize. When displaying a dark image in which unevenness is easily recognized, uneven brightness can be eliminated.

(E) Second light emission adjustment processing according to the present invention In the second light emission adjustment processing according to the present invention, the light emission of the backlight is adjusted according to the presence or absence of a non-display area (for example, a letterbox) in the video. The configuration of the display device is the same as that of the display device of the first embodiment shown in FIG.
FIG. 6 is a flowchart showing the second light emission adjustment processing in the present invention.
A video signal for one screen is input to the video holding unit 20 and the video processing unit 22 from a video player (not shown) (step S10). The video processing unit 22 detects the presence / absence of a letterbox from the video signal, and inputs a signal indicating the presence / absence of the letterbox to the control unit 24 (step S11). In step S <b> 11, if a signal indicating that there is a letterbox is input to the control unit 24, the control unit 24 instructs the backlight unit 30 to emit all LEDs, and the light emission adjustment unit of the backlight unit 30. 12 (FIG. 3) turns on the switch SW, and causes all LEDs (LED 1 with high irradiation light and LED 3 with low irradiation light) to emit light (step S12). Thus, when an image with a letterbox is input, the backlight unit 30 operates as shown in FIG. On the other hand, if a signal indicating that there is no letterbox is input to the control unit 24 in step S11, the control unit 24 instructs the backlight unit 30 to emit only the LED with strong irradiation light, and the backlight unit. The light emission adjusting unit 12 of 30 turns off the switch SW and causes only the LED 1 with strong irradiation light to emit light (step S13). As a result, when an image without a letterbox is input, the backlight unit 30 operates as shown in FIG. Thereafter, it is determined whether or not there is a video signal for one screen from the video player (step S14). If there is no video signal for one screen from the video player, the light emission adjustment process is terminated, and one screen from the video player. If there are enough video signals, the processes in steps S10 to S13 are repeated.

  According to the second light emission adjustment process, it is detected whether or not there is a non-display area (for example, a letterbox) in the video information. If there is a non-display area, all the LEDs of the backlight unit 30 are caused to emit light and are not displayed. If there is no area, only the LED with strong irradiation light of the backlight unit 30 is caused to emit light. Therefore, luminance unevenness can be eliminated for an image including a non-display area, and for an image including no non-display area. Can reduce power consumption.

(F) Third light emission adjustment process in the present invention In the third light emission adjustment process in the present invention, depending on the average luminance value in one screen and the presence or absence of a non-display area (for example, a letterbox) in the video, Adjust the backlight emission. The configuration of the display device is the same as that of the display device of the first embodiment shown in FIG.
FIG. 8 is a flowchart showing a third light emission adjustment process in the present invention.
A video signal for one screen is input to the video holding unit 20 and the video processing unit 22 from a video player (not shown) (step S20). The video processing unit 22 calculates an average luminance value from the video signal, and inputs this average luminance value to the control unit 24 (step S21). The control unit 24 determines whether the average luminance value is equal to or greater than a predetermined value Th (step S22). If the average luminance value is not equal to or greater than the predetermined value Th, the control unit 24 recognizes the image as a dark image, instructs the backlight unit 30 to emit all LEDs, and emits light from the backlight unit 30. The adjustment unit 12 (FIG. 3) turns on the switch SW and causes all the LEDs (the LED 1 with the strong irradiation light and the LED 3 with the low irradiation light) to emit light (step S23). On the other hand, if the average luminance value is equal to or greater than the predetermined value Th in step S22, the video processing unit 22 detects the presence / absence of a letterbox from the video signal and inputs a signal indicating the presence / absence of the letterbox to the control unit 24. (Step S24). In step S24, if a signal indicating that there is a letterbox is input to the control unit 24, the process of step S23 is performed, and the light emission adjusting unit 12 of the backlight unit 30 causes all LEDs to emit light. In step S 24, if a signal indicating that there is no letterbox is input to the control unit 24, the control unit 24 instructs the backlight unit 30 to emit only the LED with strong irradiation light. The light emission adjusting unit 12 turns off the switch SW and causes only the LED 1 with strong irradiation light to emit light (step S25). Thereafter, it is determined whether or not there is a video signal for one screen from the video player (step S26). If there is no video signal for one screen from the video player, the light emission adjustment process is terminated, and one screen from the video player. If there are enough video signals, the processing from step S20 to step S25 is repeated.

  In the third light emission adjustment process, the backlight unit 30 emits only an LED with strong irradiation light when a bright image without letterbox is input, and all other images are input. Because the LED emits light, power consumption can be reduced for a bright image with no letterbox, and uneven brightness can be eliminated for other images.

(G) Modified example of light emission adjustment processing in the present invention In the second light emission adjustment processing, when letterboxes are detected from the video signal, all the LEDs are caused to emit light. However, as shown in FIG. It is also possible to control so that all the LEDs emit light in the corresponding region, and only the LED 1 with strong irradiation light emits light in the region not corresponding to the letterbox. As a result, the light emission can be partially adjusted with respect to one image, luminance unevenness can be eliminated in the non-display area, and power consumption can be reduced in the area that is not the non-display area.

  In addition, the configuration and control procedure of the display device can be variously modified and changed within the scope of the gist of the present invention described in the claims.

It is the schematic of this invention. It is an exploded view explaining the structure of the backlight which irradiates LCD. It is a circuit block diagram which shows the circuit example of the backlight in this invention. It is a block diagram of the display apparatus in this invention. It is a flowchart which shows the 1st light emission adjustment process in this invention. It is a flowchart which shows the 2nd light emission adjustment process in this invention. It is a figure which shows the LED light emission state of the 2nd light emission adjustment process in this invention. It is a flowchart which shows the 3rd light emission adjustment process in this invention. It is a figure which shows the LED light emission state of the modification of the light emission adjustment process in this invention. It is the schematic of the conventional backlight. It is the schematic of the 1st prior art backlight. It is a figure which shows the LED light emission state of the 2nd prior art backlight.

Explanation of symbols

LED1 ... LED with strong irradiation light
LED3 ... LED with weak irradiation light
SW ... Switch 10 ... Flat light source unit 12 ... Light emission adjusting unit 22 ... Video processing unit 24 ... Control unit 28 ... Source driver 30 ... Backlight unit 32 ... Gate driver 34 ... LCD

Claims (6)

In a display device that displays video information,
An average luminance value calculating unit for calculating an average luminance value in one screen of the video information;
A backlight unit in which first light emitting diodes having strong irradiation light and second light emitting diodes having low irradiation light are alternately arranged;
It is determined whether the average luminance value calculated by the average luminance value calculation unit is equal to or greater than a predetermined value, and if the average luminance value is equal to or greater than a predetermined value, the first light emitting diode is instructed to emit light, A control unit that instructs the first light emitting diode and the second light emitting diode to emit light if the average luminance value is less than a predetermined value;
A light emission adjusting unit that adjusts a light emission state of the first light emitting diode and the second light emitting diode based on an instruction of the control unit;
A display device characterized by that. In a display device that displays video information,
A non-display area detection unit for detecting a non-display area included in the video information;
A backlight unit in which first light emitting diodes having strong irradiation light and second light emitting diodes having low irradiation light are alternately arranged;
When the non-display area is detected by the non-display area detecting unit, the first light-emitting diode and the second light-emitting diode are instructed to emit light, and when the non-display area is not detected, the first light-emitting diode is detected. A control unit for instructing the light emitting diodes to emit light,
A light emission adjusting unit that adjusts a light emission state of the first light emitting diode and the second light emitting diode based on an instruction of the control unit;
A display device characterized by that. The control unit instructs the first light emitting diode and the second light emitting diode to emit light in a region corresponding to the non-display region, and turns the first light emitting diode in a region not corresponding to the non-display region. Instruct to fire,
The display device according to claim 2. In a display method of a display device for displaying video information,
The first light emitting diode with strong irradiation light and the second light emitting diode with low irradiation light are alternately arranged,
An average luminance value within one screen of the video information is calculated,
Determining whether the average luminance value is equal to or greater than a predetermined value;
If the average luminance value is greater than or equal to a predetermined value, the first light emitting diode emits light. If the average luminance value is less than the predetermined value, the first light emitting diode and the second light emitting diode emit light. To
A display method for a display device. In a display method of a display device for displaying video information,
The first light emitting diode with strong irradiation light and the second light emitting diode with low irradiation light are alternately arranged,
Detecting a non-display area included in the video information;
When the non-display area is detected, the first light-emitting diode and the second light-emitting diode emit light, and when the non-display area is not detected, the first light-emitting diode emits light.
A display method for a display device. When the non-display area is detected, the first light emitting diode and the second light emitting diode emit light in an area corresponding to the non-display area, and the first light emission in an area not corresponding to the non-display area. Light emitting diode,
The display method of a display device according to claim 5.

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