JP2008301167A - Liquid crystal television receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal television receiver capable of adjusting display size of video according to change of the video and reducing power consumption without sacrificing contrast of the display video on a liquid crystal display panel when the video image of a broadcast program changes into the one of a scene which is suitable for display on a large screen and the one which is not so at any time. <P>SOLUTION: A position and size of a face of a person included in the video of the broadcast program under display by the liquid crystal display panel 20 are detected, a matching status between a detection result of the position and the size of the face and standard face information regarding the position and the size of an image of the face of the person in the display video by the liquid crystal display panel 20 is discriminated, display size of the video of the broadcast program on the liquid crystal display panel 20 is switched according to discrimination results of the matching status, light sources 18, 19 which illuminate a non-display area of the video on the liquid crystal display panel 20 are turned off and light sources 18, 19 which illuminates a display area of the video image is lit according to switching of the display size. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display panel that displays video of a broadcast program and a liquid crystal television receiver that includes a light source that illuminates it from the back.

The liquid crystal television receiver includes a liquid crystal display panel that displays video of a broadcast program and a plurality of light sources (so-called backlights) that illuminate the panel from the back. As the backlight, a cold cathode tube (fluorescent tube) that emits combined light of red, green, and blue wavelengths is generally used. In addition, the light of the cold cathode tube tends to have a shortage of light intensity in the red wavelength band with respect to the white balance suitable for human vision. Therefore, the cold cathode tube is combined with a red light emitting diode (LED). There are also hybrid-type backlights.
By the way, nowadays, large-sized liquid crystal television receivers have become widespread, and as a result, it has become possible to provide realistic images even when viewing broadcast programs related to movies, sports, natural scenery, and the like.
On the other hand, some broadcast programs include scenes in which video display on a large screen is not appropriate, such as scenes that give viewers a sense of discomfort or discomfort when the video is displayed on a large screen. For example, in broadcast programs such as news and wide shows, scene reports and other scenes are videos that you want to see on a large, realistic screen, but the scenes that newscasters and moderators will take close-ups in the studio Is an image in which a human face is projected with almost no change, and when the image is displayed on a large screen, the viewer may feel a sense of oppression or discomfort.
On the other hand, for example, Patent Document 1 proposes a television receiver that changes the display size of a video on a liquid crystal display panel in accordance with the genre of a broadcast program that is displaying the video.

In addition, a large liquid crystal television receiver has a large power consumption because it includes a large liquid crystal display panel and a large number of light sources for backlights that illuminate the entire back surface. For example, in a 52-inch liquid crystal television receiver, the power consumption of the entire apparatus is about 320 W, and the power consumption of the backlight is about 220 W (about 70%). In this way, in a liquid crystal television receiver, the power consumption of the backlight accounts for the majority of the power consumption of the entire device, so control of the lighting state of the backlight is very important for power saving of the entire device. Become.
Conventionally, Patent Document 2 discloses a technique for reducing the power supplied to the backlight when the output voltage of the battery decreases for the purpose of extending the operation time of the battery.
Further, in Patent Document 3, in order to maintain the brightness of the screen in an appropriate state according to the video content, the luminance of the backlight is changed according to the luminance (gradation) level of the video displayed on the liquid crystal display panel. The technology to be shown is shown.
On the other hand, Patent Literature 4 and Patent Literature 5 disclose techniques for easily and accurately detecting a face and its orientation based on an image captured by a camera.
Japanese Patent Laid-Open No. 10-108108 JP-A-6-205343 International Publication No. 2003/038799 Pamphlet JP 2001-101429 A JP 2006-259900 A

However, as described above, even in one broadcast program, the video of the broadcast program changes from time to time to a video representing a scene suitable for display on a large screen and a video representing a scene other than that. Therefore, as shown in Patent Document 1, when the display size of the video is changed in accordance with the genre of the broadcast program, even a video to be viewed on a large screen with a sense of reality is displayed in a small size. There was a problem that there was.
Further, as disclosed in Patent Document 2, when the power supply to the backlight is reduced by giving priority to reducing the power consumption of the device, there is a problem that the contrast of the display image on the liquid crystal display panel is sacrificed.
Also, in any of Patent Documents 1 to 3, when the video of a broadcast program changes from time to time, the video of a scene suitable for display on a large screen and the video of a scene that is not so, the display size of the video is optimized. There is no disclosure or suggestion of techniques that are effective for this purpose.
Accordingly, the present invention has been made in view of the above circumstances, and the purpose of the present invention is to change the video of a broadcast program from time to time of a scene suitable for display on a large screen and a video of a scene other than that. To provide a liquid crystal television receiver capable of optimizing the video display size according to the change and reducing the power consumption without sacrificing the contrast of the video displayed on the liquid crystal display panel. In particular, scenes that give a viewer a feeling of oppression or discomfort when displayed on a large screen, such as scenes in which a person's face is projected at a fixed position with almost no change, or scenes in which a person's face is projected greatly Other scene videos are automatically discriminated, and the display size of the displayed broadcast program video can be optimized according to the discrimination result, and the LCD panel can be optimized. To provide a liquid crystal television receiver capable of reducing power consumption without sacrificing the contrast of the display image at.

In order to achieve the above object, a liquid crystal television receiver according to the present invention includes a liquid crystal display panel for displaying broadcast program images and a plurality of light sources (light sources for backlight) that illuminate the liquid crystal display panel from the back side. And the following components (1) to (5).
(1) Face arrangement information storage means for storing face arrangement information relating to the position and size of a human face image in a display image by the liquid crystal display panel.
(2) Face detecting means for detecting the position and size of a human face image included in the video of the broadcast program being displayed on the liquid crystal display panel.
(3) Status of matching between the position and size of the human face image detected by the face detection means and the position and size of the human face image based on the face arrangement information stored in the face arrangement information storage means Means for determining a face arrangement match status.
(4) Video size switching means for switching the display size of the video of the broadcast program on the liquid crystal display panel according to the determination result by the face arrangement match situation determination means.
(5) In response to switching of the video display size by the video size switching means, the light source that illuminates the non-display area of the video of the broadcast program on the liquid crystal display panel is turned off, and the video display area of the broadcast program is Light source blinking control means for turning on the light source to be illuminated.

The liquid crystal television receiver according to the present invention includes a scene image in which a human face is projected at a fixed position with almost no change (for example, a scene image in which a newscaster or the like is a close-up in a studio) and other scene images. Is automatically determined, and the display size of the video of the broadcast program being displayed is automatically switched according to the determination result. As a result, the liquid crystal television receiver according to the present invention, when the video of the broadcast program changes from time to time, the video of the scene suitable for display on a large screen and the video of the scene not so, the video according to the change. Display size can be optimized.
Furthermore, the liquid crystal television receiver according to the present invention is configured to turn off and turn on the light source that illuminates each of the non-display area and the display area of the video of the broadcast program on the liquid crystal display panel according to switching of the video display size. To control. As a result, the liquid crystal television receiver according to the present invention can reduce power consumption without sacrificing the contrast of the display image on the liquid crystal display panel.

By the way, the video of a broadcast program shot in a studio is a video in which a human face image is enlarged in a predetermined area including the center of the screen. The position, size, and number of the human face images are taken. Differ for each broadcast program.
Therefore, in the liquid crystal television receiver according to the present invention, the face arrangement information storage unit stores the broadcast program identification information and the face arrangement information in association with each other, and the face arrangement match situation determination unit further includes: The match status may be determined based on the face arrangement information corresponding to the identification information of the broadcast program that is displaying an image on the liquid crystal display panel. This makes it possible to appropriately control the video display size according to the video characteristics of each broadcast program.
In order for the liquid crystal television receiver according to the present invention to store (register) the face arrangement information in the face arrangement information storage means, the following components (6), (7) and ( It is conceivable to include one or both of the constituent elements shown in 8).
(6) When it is detected that a predetermined registration operation has been performed on a predetermined operation unit, based on the identification information of the broadcast program that is displaying an image on the liquid crystal display panel and the detection result by the face detection means Face arrangement information semi-automatic registration means for storing the face arrangement information in association with the face arrangement information in the face arrangement information storage means.
(7) Program genre discriminating means for discriminating the genre of the broadcast program that is displaying video on the liquid crystal display panel based on the electronic program guide information stored in the predetermined storage means.
(8) When the determination result by the program genre determination means is a predetermined specific genre and the detection result by the face detection means satisfies a predetermined registration condition, the liquid crystal display panel Face arrangement information automatic registration means for associating identification information of the broadcast program that is displaying an image with the face arrangement information based on the detection result of the face detection means and storing the information in the face arrangement information storage means.
Thus, it becomes easy to appropriately register or update the face arrangement information, which is a criterion for switching the video display size, according to the user's preference and broadcast program reorganization. In addition, the television receiver according to the present invention includes a network communication interface for connecting to the Internet and means for appropriately downloading the face arrangement information through the Internet and storing the face arrangement information in the face arrangement information storage means, or It is also conceivable to include means for appropriately downloading face arrangement information through satellite waves or ground waves received by an antenna and storing the face arrangement information in the face arrangement information storage means.
The registration condition may be, for example, a condition that there is an image of a person's face that has a predetermined size or more and whose position change within a predetermined time is within a predetermined range. .

  According to the present invention, when the video of a broadcast program changes at any time between a video of a scene suitable for display on a large screen and a video of a scene other than that, the video display size can be optimized according to the change. Thus, the power consumption can be reduced without sacrificing the contrast of the display image on the liquid crystal display panel.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal television receiver X according to an embodiment of the present invention. FIG. 2 is a diagram showing an arrangement state of backlight light sources inside the liquid crystal television receiver X. FIG. 3 is a flowchart showing a display screen size control procedure in the liquid crystal television receiver X, and FIG. 4 is a diagram showing an example of a lighting state of a backlight light source in the liquid crystal television receiver X.

First, the configuration of the liquid crystal television receiver X according to the embodiment of the present invention will be described with reference to the block diagram shown in FIG.
The liquid crystal television receiver X extracts a video signal related to a broadcast program from a television broadcast signal received by an antenna or the like, and displays a video based on the video signal on the liquid crystal display panel 20. On the back surface of the liquid crystal display panel 20, there are provided a cold cathode tube 18 (shown as CCFL in the figure) that emits light blue and a LED 19 that emits red light, which are backlight light sources that illuminate the liquid crystal display panel 20 from the back. ing.
As shown in FIG. 1, a liquid crystal television receiver X includes a digital tuner 1, a demodulation circuit 2, a demultiplexer 3, a video decoder circuit 4, a video processing circuit 5, an image recognition circuit 6, a remote controller 7, a control circuit 8, and a remote controller. The light receiving unit 9, the liquid crystal display panel 20, the cold cathode tube 18 and the LED 19 which are light sources for the backlight, the inverter circuit 14, the LED driving circuit 15, the color sensor 16, the brightness sensor 17, the audio decoder circuit 10, and the audio processing circuit 11. , Amplifier 12, speaker 13 and the like.

The digital tuner 1 selects a carrier frequency component including a broadcast program signal instructed to be selected by the control circuit 8 and transmits the selected carrier frequency component to the demodulator 2 at the subsequent stage.
The demodulation circuit 2 demodulates a transport stream signal (Transport Stream signal: hereinafter referred to as TS signal) from the carrier frequency component transmitted from the digital tuner 1.
The demultiplexer 3 separates and extracts a video signal and an audio signal corresponding to a broadcast program to be viewed and additional data from the TS signal extracted by the digital tuner 1 and the demodulation circuit 2. Further, the demultiplexer 3 extracts a video signal and an audio signal of a broadcast program to be viewed according to a PID (Packet IDentification) received from the control circuit 8, and each signal is extracted from the video decoder circuit 4 and the video signal. The data is transmitted to each of the audio decoder circuits 10. Further, the demultiplexer 3 extracts SI (Service Information) as additional data from the TS signal and transmits it to the control circuit 8. This SI is data obtained by multiplexing information about an EPG (electronic program guide) (for example, information indicating a program name, a broadcast time, etc.).
The video decoder circuit 4 decodes the video signal received from the demultiplexer 3 and transmits the decoded video signal to the video processing circuit 5. Similarly, the audio decoder circuit 10 decodes the audio signal received from the demultiplexer 3 and transmits the decoded audio signal to the audio processing circuit 11.
The video processing circuit 5 performs various signal processing on the video signal transmitted from the video decoder circuit 4. For example, the video processing circuit 5 has a screen size switching function for switching the screen size of the video to be displayed on the liquid crystal display panel 20 to a size specified by the control circuit 8.
The audio processing circuit 11 performs various signal processing on the audio signal transmitted from the audio decoder circuit 10 in accordance with instructions from the control circuit 8. For example, equalization processing, surround processing, or the like according to the characteristics of the speaker 13 is performed. The amplifier 12 performs a process of amplifying or attenuating the audio signal processed by the audio processing circuit 11 according to an instruction from the control circuit 8 and outputs the amplified signal to the speaker 13.
The liquid crystal display panel 20 displays video (broadcast program video) based on the video signal output from the video processing circuit 5.
The brightness sensor 17 is a sensor that detects the brightness of the front side of the liquid crystal display panel 20, and the color sensor 16 is a color distribution (R, G, B) of light on the back side of the liquid crystal display panel 20. Sensor). These sensors are used for brightness (output) control of the cold cathode tube 18 and the LED 19 as will be described later.

The control circuit 8 includes an MPU 8a that is an arithmetic means, a ROM 8b (EPROM) that is a storage means in which a control program executed by the MPU 8a is stored in advance, and various types of data that are read and written (referenced or written) in processing executed by the MPU 8a. A non-volatile memory 8c for storing data is provided, and the entire liquid crystal television receiver X is controlled. The nonvolatile memory 8c is, for example, a flash memory.
The control circuit 8 acquires EPG information (electronic program guide information) based on the SI extracted by the demultiplexer 3, and stores the EPG information in the nonvolatile memory 8c. This EPG information includes information such as the program code and program title of each broadcast program, broadcast start date and time, broadcast end date and time, program genre (news, wide show, etc.), performers, and the like.
The image recognition circuit 6 converts the video signal (image) of the broadcast program based on the video signal transmitted from the video decoder circuit 4 (that is, the video signal of the broadcast program being displayed on the liquid crystal display panel 20). It is a circuit that executes an image recognition process for detecting the position and size of an included human face image (hereinafter referred to as a face image) (an example of the face detection means). This image recognition circuit 6 continuously detects the position and size of the face image for each of all the frame images in the video signal of the broadcast program or for each of the frame images sampled at a constant interval. Further, the processing result (position and size of the face image) by the image recognition circuit 6 is transmitted to the control circuit 8. The image recognition circuit 6 is a circuit realized by, for example, a DSP (Digital Signal Processor).
Here, as an example of an image processing algorithm for detecting (specifying) the position of a human face image from an image (video), for example, as shown in Patent Documents 4 and 5, etc., the positions of the pupil images of both eyes are determined. Since various algorithms such as detection are already known, description of the contents is omitted here. Similarly, an image processing algorithm for detecting (specifying) the size of a human face image from an image, for example, uses the distance between the pupil images detected as a feature of the human face image as the size of the face. For example, an algorithm for converting the length to the height can be considered.
The image recognition circuit 6 detects the position and size of each of the plurality of face images when there are a plurality of the face images in the image being displayed.

The remote control light receiving unit 9 is a signal transmission interface for receiving a radio signal by infrared from a remote control 7 (remote operation unit) for operating the liquid crystal television receiver X according to a predetermined signal transmission protocol. The remote control light receiving unit 9 acquires operation input information for the remote control 7 by infrared signal transmission, and transmits the operation input information to the control circuit 8.
The cold cathode tube 18 as a light source for the backlight of the liquid crystal display panel 20 emits combined light (light blue) of light of each wavelength of green and blue, and is configured by arranging a plurality of cold cathode tubes. ing. Similarly, the LED 19 that is a light source for the backlight is a red LED that emits light of a red wavelength, and a plurality of LEDs 19 are arranged between a plurality of cold cathode tubes 18.
FIG. 2 is a diagram illustrating an arrangement state of the light sources for the backlight (the cold cathode tubes 18 and the LEDs 19) inside the liquid crystal television receiver X.
As shown in FIG. 2, the cold cathode tubes 18 are arranged in the vertical direction in a region extending over the entire back surface of the liquid crystal display panel 20, and a plurality of LEDs 19 are equally spaced between the plurality of cold cathode tubes 18. It is arranged.

The inverter circuit 14 (shown as an INV circuit in the figure) is a circuit that adjusts the power supplied to each of the plurality of cold cathode tubes 18 in accordance with a control signal output from the control circuit 8. That is, according to the control signal transmitted from the control circuit 8, the inverter circuit 14 adjusts the brightness of the cold cathode tube 18 by PWM (Pulse Width Modulation) control and controls the turning on and off. I do. The inverter circuit 14 can individually turn on, turn off, and control the brightness of each cold cathode tube 18.
The LED drive circuit 15 is a circuit that adjusts the power supplied to the LED 19 (red LED) in accordance with a control command output from the control circuit 8. That is, the LED drive circuit 15 adjusts the brightness of the LED 19 and controls turning on and off according to the control signal transmitted from the control circuit 8. The LED driving circuit 15 can individually control lighting, extinction, and brightness for each LED 19 in one horizontal column (one row).
The control circuit 8 detects the detection level of the brightness sensor 17 that detects the brightness of the front side of the liquid crystal display panel 20 and the color sensor 16 that detects the color distribution of the light on the back side of the liquid crystal display panel 20. The brightness (light quantity) of the cold-cathode tube 18 and the brightness (light quantity) of the LED 19 are adjusted according to the detection result, but the detailed description thereof is omitted here.

Further, the non-volatile memory 8c in the control circuit 8 stores the face image (human face image) in a standard image of a broadcast program in which a video displayed on the liquid crystal display panel 20 is photographed in a studio of a broadcasting station. ) Is stored as standard face information (an example of the face arrangement information) (an example of the face arrangement information storage means). The standard screen information is stored in the nonvolatile memory 8c in association with broadcast program identification information (for example, a program name or broadcast start time used in electronic program guide information (EPG information)). That is, the standard face information is information set for each broadcast program.
The standard face information is information registered (recorded in the nonvolatile memory 8c) automatically or semi-automatically by the control circuit 8 (MPU 8a). Hereinafter, the semi-automatic registration process and the fully automatic registration process of the standard face information executed by the control circuit 8 will be described.

First, the semi-automatic registration process will be described.
The control circuit 8 monitors whether or not a predetermined registration operation has been performed on the remote controller 7 (an example of an operation unit) when an image of a broadcast program is displayed on the liquid crystal display panel 20. The registration operation is an operation performed when the user (viewer) decides to display the image being displayed on the liquid crystal display panel 20 on a small-size screen. For example, the registration operation is an operation of pressing a “registration key” provided on the remote controller 7 (an example of an operation unit).
When the control circuit 8 detects that the registration operation has been performed through the remote control light receiving unit 9, the position and size information of the face image detected by the image recognition circuit 6, that is, the liquid crystal Information on the position and size of the facial image in the video being displayed on the display panel 20 is acquired, and the information is used to identify the broadcast program whose video is being displayed on the liquid crystal display panel 20 (program title and broadcast start time). And the like are stored in the nonvolatile memory 8c in association with each other (an example of the face arrangement information semi-automatic registration unit). The control circuit 8 is a broadcast program that is displaying an image on the liquid crystal display panel 20 based on the current date and time measured by a timing circuit (not shown), the channel selected by the digital tuner 1, and the EPG information. Identify the identification information.

Next, the fully automatic registration process will be described.
Based on the EPG information (electronic program guide information) stored in the non-volatile memory 8c, the control circuit 8 executes a process of determining the genre of the broadcast program that is displaying the video on the liquid crystal display panel 20 (the above-mentioned) An example of program genre discrimination means). That is, the control circuit 8 is a broadcast program that is displaying an image on the liquid crystal display panel 20 based on the current date and time measured by a timing circuit (not shown), the channel selected by the digital tuner 1, and the EPG information. Identification information is specified, and a genre corresponding to the identification information is searched from the EPG information.
Further, the control circuit 8 is a case where the determination result of the broadcast program genre is a predetermined specific genre (for example, news or wide show), and the face image detected by the image recognition circuit 6 is used. When the position and size of the video signal satisfy predetermined registration conditions, the identification information of the broadcast program that is displaying the video on the liquid crystal display panel 20 and the face position and size that are the detection results of the image recognition circuit 6 are displayed. And a fully automatic registration process in which the information is stored in the nonvolatile memory 8c in association with each other (an example of the face arrangement information automatic registration unit). Note that this fully automatic registration process is automatically executed periodically, for example.
The registration condition is a condition indicating the position and size of the face image (human face image) in a standard video of a broadcast program such as news or a wide show that is shot in a broadcast station studio. It is.
Here, as the registration condition, for example, the size of the facial image is equal to or larger than a predetermined size, and the change of the position of the facial image within a predetermined time is within a predetermined range. A condition that such a face image exists in the image being displayed can be considered. More specifically, for example, the height (length in the vertical direction) of the facial image is at least a quarter of the height of the entire image, and the height direction and width of the facial image for 10 seconds. The registration condition can be considered that the change in the position of the direction is less than 5% with respect to the height and width of the entire image.
As described above, the control circuit 8 executes the semi-automatic registration process and the full-automatic registration process, so that a criterion for switching the video display size, which will be described later, according to user preference or broadcast program reorganization. It becomes easy to appropriately register or update the standard screen information.

Next, a display screen size control procedure executed by the image recognition circuit 6 and the control circuit 8 (MPU 8a) will be described with reference to a flowchart shown in FIG. At the start of the processing shown in FIG. 3, the liquid crystal television receiver X turns on all the light sources for the backlight (the cold cathode tube 18 and the LED 19), and the video of the broadcast program is displayed on the liquid crystal display panel 20. Is displayed. Further, S1, S2,... Shown below represent identification codes of processing procedures (steps).
First, the image recognition circuit 6 acquires from the control circuit 8 the standard face information corresponding to the broadcast program that is currently displaying video by the video display panel 20 (S1). At this time, the control circuit 8 identifies the broadcast program that is displaying the video on the liquid crystal display panel 20 based on the current date and time, the EPG information, and the channel selected in the digital tuner 1 (program title or broadcast start time). Etc.), and the standard face information corresponding to the identification information is read from the nonvolatile memory 8c and delivered to the image recognition circuit 6.
Further, the image recognition circuit 6 is based on the video signal transmitted from the video decoder circuit 4 (the video signal of the broadcast program being displayed on the liquid crystal display panel 20), and the video (frame image) of the broadcast program. The image recognition process for detecting the position and size of the face image included in the image is executed (S2).

  Next, the image recognition circuit 6 determines that the detection result of the facial image detected in step S2 is within a predetermined allowable range with respect to the position and size of the facial image in the standard facial information acquired in step S1. By determining (comparing) whether or not they are within the range, it is determined whether or not the detection result of the position and size of the face image matches the position and size of the face image in the standard face information (S3, face An example of an arrangement match situation determination unit). For example, the image recognition circuit 6 determines that the position and size detected in step S2 are within a predetermined allowable range for the position and size in the standard face information for a predetermined time (for example, about several seconds). ) If it is continued, it is determined that the two match, and if not, it is determined that the two do not match (non-match). When a plurality of facial images are detected in step S2, the image recognition circuit 6 compares each of the plurality of facial images with the one having the position of the facial image close in the standard facial information. The determination result (match or non-match) in step S3 is transmitted from the image recognition circuit 6 to the control circuit 8.

Then, the control circuit 8 outputs a control signal to the video processing circuit 5 according to the determination result (match or non-match) in step S3, whereby the display size of the broadcast program video on the liquid crystal display panel 20 is displayed. Is switched to a predetermined small screen size or a large screen size over the entire liquid crystal display panel 20 (S4, S6, an example of the video size switching means). That is, if it is determined in step S3 that the detection result of the position and size of the face image matches the position and size of the face image in the standard face information, the control circuit 8 displays the video of the broadcast program. The video processing circuit 5 is controlled so as to be reduced and displayed in a partial area at the center of the liquid crystal display panel 20 (S4, setting of a small screen size). The video processing circuit 5 is controlled so that the video is displayed over the entire area of the liquid crystal display panel 20 (S6, setting of a large screen size). For example, when the size of the liquid crystal display panel 20 is 52 type, the large screen size is set to a 52 type screen size, and the small screen size is set to a size corresponding to a 26 type screen.
If the video of the program to be sent changes from time to time in the video suitable for the display on the large screen and the video in the other scene by the processing in steps S4 and S6, the video display size is appropriately adjusted according to the change. Can be

Further, the control circuit 8 controls the inverter circuit 14 and the LED driving circuit 15 in accordance with the switching of the video display size by the processing of steps S4 and S6, thereby allowing the video of the broadcast program on the liquid crystal display panel 20 to be controlled. Control is performed to turn off the light source (the cold cathode tube 18 and the LED 19) that illuminates the non-display area and turn on the light source that illuminates the display area of the broadcast program image (S5, S7, an example of the light source blinking control means) ).
FIG. 4 is a diagram illustrating an example of a lighting state of the backlight light source by the processes in steps S5 and S7.
When the video display area of the broadcast program is the display area a2 having the small screen size (S4), the control circuit 8 turns on the cold cathode tube 18 and the LED 19 that illuminate the display area a2 in step S5. (Noted as “lit” in FIG. 4), and the cold-cathode tube 18 and the LED 19 that illuminate the non-display area (area excluding the area a1) of the image are turned off as much as possible (FIG. 4). In FIG.
On the other hand, when the video display area of the broadcast program is the large screen size display area a1 (S6), the control circuit 8 turns on all the cold cathode tubes 18 and LEDs 19 in step S7.
For example, when the size of the liquid crystal display panel 20 (the large screen size) is 52 type, the size of the video display area is reduced to half the size of the entire display area, and the backlight light source for illuminating the non-display area of the video is used. By controlling the power supply, it is possible to reduce the power consumption to the extent corresponding to a 37-inch liquid crystal television receiver.
Therefore, the power consumption of the liquid crystal television receiver X can be greatly reduced without sacrificing the contrast of the display image on the liquid crystal display panel 20 by the processing in steps S5 and S7.

Further, the control circuit 8 is a broadcast program that is displaying an image on the liquid crystal display panel 20 based on the current date and time measured by a timing circuit (not shown), the channel selected by the digital tuner 1, and the EPG information. By identifying the identification information and monitoring the change in the identification information, it is determined at any time whether or not the broadcast program displaying the video on the liquid crystal display panel 20 has been switched (S8).
If it is determined in step S8 that the broadcast program that is displaying video on the liquid crystal display panel 20 has been switched, the processes in steps S1 to S7 described above are repeated, while the broadcast program is switched. If it is determined that it is not, the processes in steps S2 to S7 described above are repeated.

In the embodiment described above, the inverter circuit 14 and the LED drive circuit 15 can turn on and off the light sources 18 and 19 for the backlight in units of one row (one row in the horizontal direction). However, the unit that can be turned on / off can be considered to be another unit. For example, the inverter circuit 14 and the LED driving circuit 15 can turn on and off the light sources 18 and 19 for backlight in units of two rows (two columns in the horizontal direction) It is conceivable that the LED drive circuit 15 can be turned on and off in units of a plurality of adjacent LEDs 19.
In the above-described embodiment, an example in which the backlight is a hybrid type composed of both light sources of the cold cathode tube 18 and the LED 19 is shown. However, only the cold cathode tube that emits white light, only the LED that emits white light, or A backlight composed of a combination of RGB three-color LEDs is also conceivable.

  The present invention is applicable to a liquid crystal television receiver.

1 is a block diagram illustrating a schematic configuration of a liquid crystal television receiver X according to an embodiment of the present invention. The figure showing the arrangement state of the light source for backlights in the inside of liquid crystal television receiver X. 7 is a flowchart showing a procedure for controlling the display screen size in the liquid crystal television receiver X. The figure showing an example of the lighting state of the light source for backlights in the liquid crystal television receiver.

Explanation of symbols

X: Liquid crystal television receiver 1: Digital tuner 2: Demodulation circuit 3: Demultiplexer 4: Video decoder circuit 5: Video processing circuit 6: Image recognition circuit 7: Remote control 8: Control circuit 9: Remote control light receiving unit 10: Audio decoder Circuit 11: Audio processing circuit 12: Amplifier 13: Speaker 14: Inverter circuit 15: LED drive circuit 16: Color sensor 17: Brightness sensor 18: Cold cathode tube (light source for backlight)
19: LED (light source for backlight)
20: Liquid crystal display panels S1, S2,...: Step (processing procedure)

Claims (5)

A liquid crystal television receiver comprising a liquid crystal display panel for displaying a broadcast program image and a plurality of light sources for illuminating the liquid crystal display panel from the back side,
Face arrangement information storage means for storing face arrangement information relating to the position and size of an image of a human face in a display image by the liquid crystal display panel;
Face detection means for detecting the position and size of a human face image included in the video of the broadcast program being displayed by the liquid crystal display panel;
A matching situation between the position and size of the human face image detected by the face detection means and the position and size of the human face image based on the face arrangement information stored in the face arrangement information storage means is determined. A face arrangement match situation discrimination means;
Video size switching means for switching the display size of the video of the broadcast program on the liquid crystal display panel according to the determination result by the face arrangement match situation determination means;
In response to switching of the video display size by the video size switching means, the light source that illuminates the non-display area of the video of the broadcast program on the liquid crystal display panel is turned off, and the display area of the video of the broadcast program is illuminated Light source blinking control means for turning on the light source;
A liquid crystal television receiver, comprising: The face arrangement information storage means stores the identification information of the broadcast program and the face arrangement information in association with each other,
2. The liquid crystal according to claim 1, wherein the face arrangement matching status determination unit determines the matching status based on the face arrangement information corresponding to identification information of the broadcast program that is displaying an image on the liquid crystal display panel. Television receiver.   The face arrangement based on the identification information of the broadcast program that is displaying an image on the liquid crystal display panel and the detection result by the face detection means when it is detected that a predetermined registration operation is performed on a predetermined operation unit 3. The liquid crystal television receiver according to claim 2, further comprising face arrangement information semi-automatic registration means for storing information in association with information in the face arrangement information storage means. Program genre discriminating means for discriminating the genre of the broadcast program being displayed on the liquid crystal display panel based on the electronic program guide information stored in the predetermined storage means;
When the determination result by the program genre determination means is a predetermined specific genre, and the detection result by the face detection means satisfies a predetermined registration condition, an image is displayed on the liquid crystal display panel. Face arrangement information automatic registration means for associating and storing the identification information of the broadcast program in the face arrangement information based on the detection result by the face detection means in the face arrangement information storage means;
A liquid crystal television receiver according to claim 2, comprising:   5. The liquid crystal according to claim 4, wherein the registration condition is that there is an image of a human face having a predetermined size or more and a change in position within a predetermined time within a predetermined range. Television receiver.

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