JP2010117682A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device in which a driving period of an emergency power source can be considerably extended. <P>SOLUTION: The display device, which functions by power feeding from a commercial power source AC in normal operation and functions by power feeding from the emergency power source Vdc in an emergency, includes: a power failure detecting section 5 which detects power failure of the commercial power source AC; and switching sections (Q1, Q2, D1) which switch to display only a portion of an area out of an entire display screen upon receipt of a power failure signal from the power failure detection section 5. The emergency power source Vdc is a battery, and the commercial power source AC and the battery are changed over when receiving the detection signal from the power failure detecting section 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device that operates with a commercial power supply at all times and an emergency power supply in an emergency.

  In recent years, the spread of liquid crystal televisions and plasma televisions compatible with digital broadcasting has been rapidly progressing mainly in ordinary households. Furthermore, not only ordinary homes but also large screens with screen sizes exceeding 40 inches are spreading as information displays in public facilities such as stations, airports and shopping malls. The information display mainly displays advertisements and promotions, but can receive a digital broadcast signal and function as a television. Information displays are installed in public places where many people gather, so they can also function as emergency lighting and guide lights to eliminate confusion and anxiety during emergencies. desired.

  Normally, an information display is operated by power supply from a commercial power supply. However, in order to function in an emergency, it is necessary to operate by power supply from an emergency power supply. The emergency power supply is generally a battery, and there are a built-in system and a separate system. In some cases, an external uninterruptible power supply is provided, or a power generation system is provided. In any case, in order to use the emergency power supply, which is a limited power supply in an emergency, and to continue the function of the emergency lighting function and the guide light as long as possible, the power consumption is minimized and the drive time is reduced. Significant growth is a challenge. In addition, suppressing power consumption in an emergency leads to miniaturization of the emergency power supply.

In order to solve the above-described problems, a display device that is not used for emergency purposes but can extend the driving time of the battery is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2005-210707). ing. The display device disclosed in Patent Literature 1 controls a broadcast content detection unit and at least one of backlight luminance, liquid crystal drive spatial resolution, and time resolution based on CM information detected by the broadcast content detection unit. The display control unit controls the backlight brightness or the liquid crystal drive of the liquid crystal panel based on the CM information to reduce power consumption and extend the battery drive time. As an embodiment of Patent Document 1, a mode is disclosed in which power consumption is reduced by changing the display screen to a small screen during CM and using partial lighting of the backlight in accordance with the small screen.
JP 2005-210707 A

  However, the display device of Patent Document 1 produces a power saving effect by partially lighting the backlight. However, since the liquid crystal panel is driven by one liquid crystal driving circuit, the liquid crystal panel operates as a whole. Therefore, the liquid crystal driving circuit controls the black display so that the image is not displayed. Therefore, the display device of Patent Document 1 needs to drive the liquid crystal panel even in a place where no video is displayed, and power consumption is required. The backlight of Patent Document 1 is dimmed and controlled by a PWM signal input to the inverter. For example, even when the backlight is turned off, it is necessary to control the turning off by inputting a signal of Duty: 0% as a PWM signal to the inverter. That is, the display device of Patent Document 1 requires control power for turning off the control in the inverter control unit even when the discharge lamp is turned off.

  As described above, the display device of Patent Document 1 has a problem that it requires power for driving the liquid crystal panel at a location where no image is displayed and power for inverter control of the backlight that is turned off. . Particularly in a large display device for information and the like, the power consumption can be a factor for shortening the drive time of the emergency power supply.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a display device capable of significantly extending the driving time of an emergency power supply.

  In order to solve the above-mentioned problems, the invention of claim 1 is a display device that functions by power supply from the commercial power supply AC at all times and functions by power supply from the emergency power supply Vdc in an emergency, as shown in FIG. A power failure detection means 5 for detecting a power failure of the commercial power supply AC, and a means for switching to display only a part of the entire display screen in response to the power failure detection signal from the power failure detection means 5 ( Q1, Q2, D1) are provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, as shown in FIG. 1, the emergency power source Vdc is a battery, and the commercial power source AC and the battery are detected from the power failure detection means 5. And switching.

  The invention of claim 3 comprises the emergency signal receiver 25 for receiving an emergency signal from the outside as shown in FIG. 8 in the invention of claim 1 or 2, wherein the power failure detection means 5 detects a power failure, In addition, when an emergency signal is received by the emergency signal receiving unit 25, display corresponding to the information of the emergency signal (see FIG. 9) is performed in a partial area of the display screen.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, as shown in FIG. 11, the power failure detection means 5b detects a power failure in response to a signal from the emergency power supply (standby power supply device 7b). It is characterized by that.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, as shown in FIG. 1, the display device includes a backlight BL including a plurality of light sources La1 to La3, and the plurality of light sources La1 to La3. Are divided into a first light source group La3 that irradiates only a partial region of the display screen and a second light source group La1 and La2 that irradiates other regions, and the light source groups La1 to La3 are respectively lit. When a power failure is detected by the power failure detection means 5 as shown in FIG. 3, only the lighting circuit 3 of the first light source group La3 is fed from the emergency power source Vdc. In response, the first light source group La3 is turned on.

  According to the invention of claim 6, in the invention of claim 5, as shown in FIG. 4, the liquid crystal panel 20 and the liquid crystal panel in the region irradiated by the first light source group La3 among the plurality of light sources La1 to La3 are driven. A first liquid crystal panel driver 24 and a second liquid crystal panel driver 23 for driving the liquid crystal panel in the region irradiated by the second light source groups La1 and La2, and the power failure detection means 5 detects a power failure. In this case, only the first liquid crystal panel driver 24 operates by receiving power from the emergency power supply Vdc.

  According to a seventh aspect of the present invention, when the power failure detection means 5 detects a power failure in the invention of the fifth or sixth aspect, the first light source group La3 blinks and lights up at a cycle of a critical flicker frequency or more. It is characterized by that. Here, the critical flicker frequency is a limit frequency at which human beings cannot sense blinking.

  The invention according to claim 8 is the invention according to claims 5 to 7, wherein the light source of the backlight is a discharge lamp or a light emitting diode, and includes a direct-type backlight unit (FIG. 2) configured using them. It is characterized by that.

  According to a ninth aspect of the present invention, in the fifth to seventh aspects of the present invention, the light source of the backlight is a discharge lamp or a light emitting diode, and includes a sidelight type backlight unit (FIG. 5) configured by using them. It is characterized by that.

  The display device of claim 1 is switched to display only a part of the entire display screen when the power failure is detected by the power failure detection means and operated by power supply from the emergency power supply. Compared with displaying on the screen, power consumption can be greatly reduced. Accordingly, the drive time of the display device by the emergency power source, which is a limited power source in an emergency, can be greatly extended, and the emergency power source can be downsized. In addition, various display devices that are normally used as displays for televisions, advertisements, and advertisements can be used as emergency lighting and guide lights.

  The display device according to claim 2 receives the power failure detection signal from the power failure detection means and switches between the commercial power source and the battery as the emergency power source, so that the power source can be smoothly switched in an emergency.

  In the display device according to claim 3, when a power failure is detected by the power failure detection means and an emergency signal is received by the emergency signal receiving unit, information on the emergency signal is displayed in a part of the display area of the entire display screen. Since the corresponding display is performed, it is possible to eliminate confusion and anxiety in an emergency, and to provide emergency useful information such as the cause of a power failure and an evacuation route.

  The display device according to claim 4 can easily determine power outage or non-power outage by receiving a signal from an external emergency power supply and determining whether or not the emergency power supply is operating.

  In the display device according to the fifth aspect, since the lighting device of the second light source group is not supplied with power in an emergency, it is possible to reduce power consumed for control for turning off the light.

  In the display device according to claim 6, since the second liquid crystal panel driver is not supplied with power in an emergency, the power consumed by the second liquid crystal panel driver and the liquid crystal panel driven by the second liquid crystal panel driver is reduced. it can.

  The display device according to claim 7 blinks and lights up the first light source group at a cycle of a critical flicker frequency at which humans can feel blinking, so display contents displayed in a part of the display area of the entire display screen Can be easily noticed by humans.

  Since the display device according to the eighth aspect includes the direct-type backlight unit, the light extraction efficiency from the backlight is high.

  Since the display device according to the ninth aspect includes a side light type backlight, the display device can be configured with a small number of backlights, and the cost is low.

(Embodiment 1)
An embodiment of a display device according to the present invention will be described using an example of a liquid crystal display device.

  First, the configuration of the liquid crystal display device of this embodiment will be briefly described with reference to FIG. The present liquid crystal display device stores U-shaped discharge lamps La1 to La3 which are backlights BL of the liquid crystal display device, the discharge lamps La1 to La3, and a storage case 11 having a front surface made of metal, for example, A reflective plate 12 disposed on the bottom surface on the open side of the storage case 11 and a liquid crystal panel 20 installed on the open surface of the storage case 11 as light parallelized by averaging the light emitted from the discharge lamps La1 to La3. The liquid crystal display device of the direct illumination system is composed of an optical sheet 13 for supplying to the liquid crystal and a liquid crystal panel 20 for displaying an image using a light beam emitted from the optical sheet 13 as a backlight. Here, the optical sheets 13 are formed by, for example, laminating a diffusion plate 13a, a diffusion sheet 13b, and a lens sheet 13c in order from the back side. The lighting devices for the discharge lamps La1 to La3 and the driver for the liquid crystal panel 20 are not shown, but they are generally arranged on the back side or the side surface side of the storage case 11.

  In the liquid crystal display device of this embodiment, as described above, the backlight is constituted by the U-shaped discharge lamps La1 to La3 as described above. In general, the information display has a large size exceeding 40 inches. However, in the case of a 40-inch liquid crystal display device, the backlight is composed of around 16 straight-line cold cathode lamps. The power consumption per cold cathode lamp is about 10 W, although it depends on the tube diameter of the cold cathode lamp and the enclosed gas.

  Next, the system configuration of the liquid crystal display device of this embodiment will be described with reference to FIG. The system of the present liquid crystal display device smoothes the rectified pulsating voltage connected to both ends of the diode bridge DB into a DC voltage with less ripples, and a diode bridge DB that rectifies the AC voltage of the commercial power supply AC. An electrolytic capacitor C1, a chopper circuit 4 that is connected to both ends of the electrolytic capacitor C1, for example, steps down the DC voltage, and a lighting circuit 1 that lights the discharge lamps La1 to La3 using the output voltage of the chopper circuit 4 as an input voltage. 3, a liquid crystal panel driver 21 that drives the liquid crystal panel 20, and a video processing circuit 22 that controls the liquid crystal panel driver 21 in order to display an image based on an external video signal on the liquid crystal panel 20. Yes. Further, at the output end of the chopper circuit 4, switching means Q <b> 2 for switching supply / cutoff of the power supply voltage from the chopper circuit 4 to the lighting circuits 1 to 3, the liquid crystal panel driver 21 and the video processing circuit 22 is provided. It has been.

  An emergency power supply Vdc charged by the emergency power supply charger 6 connected to the commercial power supply AC has an emergency output to the lighting circuit 3, the liquid crystal panel driver 21, and the video processing circuit 22. A switching means Q1 for switching between supply and interruption of the power supply voltage from the power supply Vdc is provided. Since the diode D1 is provided on the power supply line from the chopper circuit 4 to the lighting circuit 3, power is not supplied from the emergency power supply Vdc to the lighting circuit 1 and the lighting circuit 2. Further, the liquid crystal display device is provided with a power failure detection means 5 for monitoring the voltage of the electrolytic capacitor C1 and detecting a power failure. The emergency power supply charger 6 and the emergency power supply Vdc may be built in the liquid crystal display device or may be installed outside the liquid crystal display device.

  Subsequently, the operation of the liquid crystal display device of the present embodiment will be described with reference to FIGS. 1 and 3A to 3D. The system of the present liquid crystal display device operates differently at all times and in an emergency, and the emergency here is a state involving at least a power failure.

  First, the system operation of the present liquid crystal display device at all times will be described with reference to FIG. 1. The power failure detection means 5 is in a state where no power failure has been detected (a state in which it is determined to be always), and the switching means Q2. Is switched on and the switching means Q1 is controlled to be off. That is, normally, the power supply voltages of the lighting circuits 1 to 3, the liquid crystal panel driver 21, and the video processing circuit 22 are supplied from the chopper circuit 4. Further, at all times, an image based on an image signal from the outside is displayed on the liquid crystal panel 20. Further, the emergency power supply Vdc is charged by the emergency power supply charger 6 connected to the commercial power supply AC.

  Next, the operation of the present liquid crystal display device in an emergency will be described. The power failure detection means 5 detects a power failure by detecting that the voltage of the electrolytic capacitor C1 has dropped, turns off the switching means Q2, and turns on the switching means Q1. That is, in an emergency, the power supply lines from the chopper circuit 4 to the lighting circuits 1 to 3, the liquid crystal panel driver 21, and the video processing circuit 22 are shut off by turning off the switching means Q 2, and the switching means Q 1 is replaced. When turned on, the power supply voltage is supplied from the emergency power supply Vdc charged by the emergency power supply charger 6 to the lighting circuit 3, the liquid crystal panel driver 21, and the video processing circuit 22 for lighting the discharge lamp La3. At this time, the power supply voltage is not supplied from the emergency power supply Vdc to the lighting circuit 1 and the lighting circuit 2 due to the action of the diode D1.

  Therefore, during an emergency in which a power failure is detected by the power failure detection means 5, only the lighting circuit 3 among the lighting circuits 1 to 3 is supplied with power from the emergency power source Vdc, and the back shown in FIG. Since only the discharge lamp La3 is turned on among the lights, the display area of the present liquid crystal display device is a display in which the discharge lamp La3 is arranged directly below the entire display area as shown in FIG. 3B. Only area. The display area in which the discharge lamps La1 and La2 are arranged directly below the entire display area is a non-display area.

  Further, the video processing circuit 22 receives the power failure detection signal from the power failure detection means 5 and displays the display based on the external video signal on the region where the discharge lamp La3 can be irradiated in the liquid crystal panel (all display regions). The liquid crystal panel driver 21 is controlled so as to switch to the emergency display. For example, a white screen is displayed in the display area as shown in FIG. 3B, and the luminous flux is used for emergency lighting, or “power outage” is displayed in the display area as shown in FIG. Control is performed to display characters or to display the guidance information in the display area as shown in FIG.

  As described above, the liquid crystal display device according to the present embodiment functions by power supply from the commercial power supply AC at all times, switches power from the commercial power supply AC to the emergency power supply Vdc in emergency, and supplies power to the backlight BL. By turning on only a part of the display area, a part of the entire display screen is used as a display area.

  Next, the effect of this embodiment will be described. First, the display device of the present embodiment can use a display device that is usually used as a display for television, advertisement, or promotion as an emergency lighting or guide light. Further, in an emergency, the power failure detection means 5 detects a power failure, turns off the switching means Q2 and turns on the switching means Q1 so that the power feeding means is switched from the commercial power supply AC to the emergency power supply Vdc. Since the operation of the diode D1 is performed so that only the discharge lamp La3 of the backlight BL is lit, only the area of the liquid crystal panel 20 in which the discharge lamp La3 is arranged directly below the display screen is the display area. Compared with the case where display is performed on the entire display screen, power consumption can be significantly reduced, and the driving time of the display device using the emergency power supply Vdc, which is a limited power supply in an emergency, can be greatly extended.

(Embodiment 2)
The configuration of the liquid crystal display device of the present embodiment is the same as that of FIG.

  Next, the system configuration of the liquid crystal display device of this embodiment is shown in FIG. The system of this liquid crystal display device is connected to both ends of the diode bridge DB for full-wave rectification of the AC voltage of the commercial power supply AC, and smoothes the full-wave rectified pulsating voltage to a DC voltage with less ripple. An electrolytic capacitor C1 that is connected to both ends of the electrolytic capacitor C1, for example, a chopper circuit 4 that steps down the DC voltage, and a lighting circuit 1 that lights the discharge lamps La1 to La3 using the output voltage of the chopper circuit 4 as an input voltage. -3, liquid crystal panel drivers 23 and 24 for driving the liquid crystal panel 20, and a video processing circuit 22 for controlling the liquid crystal panel drivers 23 and 24 in order to display an image based on an external video signal on the liquid crystal panel 20. It consists of and. Here, the liquid crystal panel driver 23 is a liquid crystal panel driver for driving a liquid crystal panel area arranged in front of the discharge lamps La1 and La2, and the liquid crystal panel driver 24 is a liquid crystal panel area arranged in front of the discharge lamp La3. Is a liquid crystal panel driver for driving.

  The output terminal of the chopper circuit 4 has switching means Q2 for switching supply and cut-off of the power supply voltage from the chopper circuit 4 to the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22. Is provided.

  On the other hand, an emergency power supply Vdc to the lighting circuit 3, the liquid crystal panel driver 24, and the video processing circuit 22 is connected to the output terminal of the emergency power supply Vdc charged by the emergency power supply charger 6 connected to the commercial power supply AC. A switching means Q1 for switching between supply and interruption of the power supply voltage from is provided. Since the diode D1 is provided on the power supply line from the chopper circuit 4 to the lighting circuit 3, power is not supplied from the emergency power supply Vdc to the lighting circuit 1, the lighting circuit 2, and the liquid crystal panel driver 23. . Further, the liquid crystal display device is provided with a power failure detection means 5 for monitoring the voltage of the electrolytic capacitor C1 and detecting a power failure.

  Subsequently, the operation of the liquid crystal display device of this embodiment will be described with reference to FIGS. 4, 3 </ b> A, and 3 </ b> B. First, with reference to FIG. 4, the system operation of the present liquid crystal display device at all times will be described. The power failure detection means 5 is in a state where no power failure is detected (a state in which it is determined to be always), and the switching means Q2. Is switched on and the switching means Q1 is controlled to be off. That is, normally, the power supply voltages of the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22 are supplied from the chopper circuit 4. Further, at all times, an image based on an image signal from the outside is displayed on the liquid crystal panel 20. Further, the emergency power supply Vdc is charged by the emergency power supply charger 6 connected to the commercial power supply AC.

  Next, the operation of the present liquid crystal display device in an emergency will be described. The power failure detection means 5 detects a power failure by detecting that the voltage of the electrolytic capacitor C1 has dropped, turns off the switching means Q2, and switches the switching means. Turn on Q1. That is, in an emergency, the power supply lines from the chopper circuit 4 to the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22 are shut off by turning off the switching means Q 2, and instead the switching means. By turning on Q1, the power supply voltage is supplied to the lighting circuit 3, the liquid crystal panel driver 24, and the video processing circuit 22 for lighting the discharge lamp La3 from the emergency power supply Vdc charged by the emergency power supply charger 6. The At this time, the power supply voltage is not supplied from the emergency power supply Vdc to the lighting circuit 1, the lighting circuit 2, and the liquid crystal panel driver 23 due to the action of the diode D1.

  Therefore, in the event of an emergency in which a power failure is detected by the power failure detection means 5, only the discharge lamp La3 in the backlight shown in FIG. 3A is lit by receiving power supply from the emergency power supply Vdc. . Further, as shown in FIG. 3B, the display area of the present liquid crystal display device is only the area of the liquid crystal panel in which the discharge lamp La3 is arranged immediately below the entire display area and the liquid crystal panel driver 24 is driven. . Of the entire display area, the discharge lamps La1 and La2 are arranged directly below, and the area of the liquid crystal panel 20 driven by the liquid crystal panel driver 23 is a non-display area. Further, the video processing circuit 22 receives the power failure detection signal from the power failure detection means 5 and controls the liquid crystal panel driver 24 to display, for example, a white screen in the display area from the display based on the external video signal. However, the display in an emergency is not limited to the white screen, and may be a display as shown in FIGS.

  As described above, the liquid crystal display device according to the present embodiment includes the liquid crystal panel driver 23 that drives the liquid crystal panel region in which the discharge lamps La1 and La2 that are turned off in an emergency are arranged, and the discharge lamp La3 that is turned on in an emergency. And a liquid crystal panel driver 24 for driving the liquid crystal panel region arranged in the above. In an emergency, only the liquid crystal panel driver 24 that drives the liquid crystal panel region in which the discharge lamp La3 is disposed directly below the liquid crystal panel drivers 23 and 24 is supplied with power from the emergency power supply Vdc, and the discharge lamps La1 and La2 The liquid crystal panel driver 23 that drives the liquid crystal panel region arranged immediately below is not supplied with power. That is, when the discharge lamps La1 and La2 are extinguished, the liquid crystal panel driver 23 is also stopped together, so that the power consumption in the liquid crystal panel driver 23 and the consumption in the liquid crystal panel 20 driven by the liquid crystal panel driver 23 are reduced. Electric power can be reduced.

(Embodiment 3)
The configuration of the liquid crystal display device of this embodiment will be described with reference to FIG. The present liquid crystal display device is made of, for example, a metal, a storage case (not shown) whose front surface is open, a reflector 12 disposed on the bottom surface on the open side of the storage case, and an acrylic, for example, of the reflector 12 A light guide plate 14 disposed on the storage case, and a light emitting diode LED1 to LED6 serving as a backlight BL disposed on a side surface of the light guide plate 14, and the light emitting diodes LED1 to LED6 mounted thereon Sidelight type liquid crystal display comprising a mounting substrate 15 housed in a case, optical sheets 13 disposed on the front surface of the light guide plate 14, and a liquid crystal panel 20 disposed on the front surface of the optical sheets 13. Device. The light guide plate 14 functions to uniformly shine the entire front surface of the light guided from the light emitting diodes LED1 to LED6 into the light guide plate 14 using total reflection. The reflector 12 functions to reflect the light leaked to the back surface of the light guide plate 14 to the front surface of the light guide plate 14. Although the lighting devices of the light emitting diodes LED1 to LED6 and the driver of the liquid crystal panel 20 are not shown, they are generally arranged on the back side or side surface side of the storage case.

  Next, FIG. 6 shows the system configuration of the liquid crystal display device of this embodiment. In the system of the present liquid crystal display device, the loads of the lighting circuits 1 to 3 are light emitting diodes. The light emitting diodes LED1 and LED2, the light emitting diodes LED3 and LED4, and the light emitting diodes LED5 and LED6 connected in series are respectively connected to the lighting circuit 1 and the lighting circuit. 2. The lighting circuit 3 lights up, but the others are the same as in FIG. 4 which is a system configuration diagram of the second embodiment, and thus the system configuration and description of the operation are omitted.

  In the present liquid crystal display device, an operation in an emergency when a power failure is detected by the power failure detection means 5 will be described. A light-emitting diode among the backlights shown in FIG. Only LED5 and LED6 are lit. Further, as shown in FIG. 7B, the display area of the present liquid crystal display device is a liquid crystal panel area in which light-emitting diodes LED5 and LED6 are arranged in the sidelights in the entire display area. It is driven by a liquid crystal panel driver 24 that receives power from the power source Vdc.

  Next, the effect of this embodiment will be described. Since the present embodiment is a sidelight type liquid crystal display device, a low cost configuration with a small number of backlights can be realized.

(Embodiment 4)
FIG. 8 shows a system configuration diagram of the liquid crystal display device of the present embodiment. The system configuration of the present liquid crystal display device is equipped with an emergency signal receiving unit 25 for receiving an emergency signal from the outside in addition to FIG. 4 showing the system configuration of the second embodiment. Here, the emergency signal from the outside is specifically a signal for informing a disaster such as a large earthquake or a fire.

  First, the operation of the present liquid crystal display device at all times will be described with reference to FIG. 8. The power failure detection means 5 is in a state where no power failure is detected (a state in which it is determined that it is always), and the switching means Q2 is The on / switching means Q1 is controlled to be off. That is, normally, the power supply voltages of the lighting circuits 1 to 3, the liquid crystal panel driver 23, the liquid crystal panel driver 24, and the video processing circuit 22 are supplied from the chopper circuit 4. In addition, a video based on a video signal from the outside is displayed on the liquid crystal panel 20 at all times. However, when an emergency signal from the outside is received without a power failure, the video processing circuit 22 In response to the emergency signal from the signal receiving unit 25, the display video is switched from the display based on the video signal to the display corresponding to the content of the emergency signal and displayed on the entire screen.

  Next, the operation of the present liquid crystal display device in an emergency will be described. The power failure detection means 5 detects a power failure by detecting that the voltage of the electrolytic capacitor C1 has dropped, turns off the switching means Q2, and switches the switching means. Turn on Q1. That is, in an emergency, the power supply lines from the chopper circuit 4 to the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22 are shut off by turning off the switching means Q 2, and instead the switching means. By turning on Q1, the power supply voltage is supplied to the lighting circuit 3, the liquid crystal panel driver 24, and the video processing circuit 22 for lighting the discharge lamp La3 from the emergency power supply Vdc charged by the emergency power supply charger 6. The At this time, the power source voltage is not supplied from the emergency power source Vdc to the lighting circuit 1, the lighting circuit 2, and the liquid crystal panel driver 23 due to the action of the diode D1.

  Therefore, in the event of an emergency when a power failure is detected by the power failure detection means 5, only the discharge lamp La3 in the backlight shown in FIG. 3A is turned on in response to power supply from the emergency power supply Vdc. Further, as shown in FIG. 3B, the display area of the present liquid crystal display device includes only the area of the liquid crystal panel 20 in which the discharge lamp La3 is arranged immediately below the entire display area and the liquid crystal panel driver 24 drives. Become. Of the entire display area, the discharge lamps La1 and La2 are arranged directly below, and the area of the liquid crystal panel 20 driven by the liquid crystal panel driver 23 is a non-display area.

  Furthermore, in the system of the liquid crystal display device according to the present embodiment, when the power failure is detected by the power failure detection means 5 and the emergency signal is received from the outside by the emergency signal receiver 25, the video processing circuit 22 In response to the emergency signal from the emergency signal receiver 25, information corresponding to the content of the emergency signal as shown in FIGS. 9A and 9B is displayed in the display area. FIG. 9A shows an example of display contents when an earthquake occurs, and FIG. 9B shows an example of display contents when a fire occurs.

  Here, in order to make it easy for a human to notice the display contents when performing display according to an emergency signal as shown in FIGS. 9A and 9B, the discharge lamp La3 is operated by the lighting circuit 3 so as to have a critical flicker frequency. It is good to control so that it blinks with a period of. The critical flicker frequency is a limit frequency at which human beings cannot detect blinking. Specifically, it is desirable to set the cycle of blinking lighting to a cycle of 30 (ms) or more. Although not shown in FIG. 8, for example, by setting the period of the dimming PWM signal input to the lighting circuit 3 to be equal to or greater than the period of the critical flicker frequency, blinking lighting can be easily realized.

  As described above, the liquid crystal display device according to the present embodiment always functions by supplying power from the commercial power supply AC. In an emergency, the power supply is switched from the commercial power supply AC to the emergency power supply Vdc, and a power failure is detected. In addition, in the state of receiving an emergency signal from the outside, the display corresponding to the information of the emergency signal is performed on a part of the display area of the entire display screen. It can provide emergency useful information such as the cause of power outages and evacuation routes. In addition, in an emergency, the backlight blinks at a frequency of the critical flicker frequency or more, so that there is an advantage that a person can easily notice the display corresponding to the information of the emergency signal.

(Embodiment 5)
FIG. 10 shows a system configuration diagram of the liquid crystal display device of the present embodiment. The liquid crystal display device of the present embodiment operates by supplying power from the standby power supply device 7a provided in the commercial power supply line in an emergency involving a power failure. The standby power supply device 7a is specifically an uninterruptible power supply (UPS power supply), and the uninterruptible power supply includes an alternating current type and a direct current type, but in the present embodiment, a direct current type is assumed. The standby power supply device 7a is provided outside the liquid crystal display device, and becomes an input power source for the liquid crystal display device instead of the commercial power source AC as an emergency power source when a power failure occurs. Further, since the functions of the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22 in FIG. 10 are the same as those in the second embodiment, description thereof is omitted.

  Next, the operation of the liquid crystal display device of this embodiment will be described with reference to FIG. In the liquid crystal display device of the present embodiment, the power failure detection means 5a is connected to the power supply line, and detects the power failure by discriminating between the AC voltage and the DC voltage.

  Here, the state in which the AC voltage from the commercial power supply AC is detected is always (no power failure), and the state in which the DC voltage from the standby power supply device 7a is detected is an emergency (power failure). The power failure detection means 5a always controls the switching means Q2 to be on and the switching means Q1 to be off. In an emergency, the power failure detection means 5a controls the switching means Q2 to be off and the switching means Q1 to be on. Input the signal. Normally, the commercial power source AC is used as the input power source, and the output voltage of the chopper circuit 4 is transferred to the lighting circuits 1 to 3, the liquid crystal panel drivers 23 and 24, and the video processing circuit 22 through the switching means Q2 by the control. Supplied. In an emergency, the standby power supply 7a is used as an input power source, and the output voltage of the chopper circuit 4 is switched via the switching means Q1 by the control of the power failure detection means 5a, the lighting circuit 3, the liquid crystal panel driver 24, It is supplied to the video processing circuit 22. Here, the output voltage from the chopper circuit 4 is not supplied to the lighting circuits 1 and 2 and the liquid crystal panel driver 23 by the action of the diode D1.

  That is, in the emergency, the liquid crystal display device of the present embodiment detects that the standby power supply 7a becomes the input power supply instead of the commercial power supply AC and is switched to the standby power supply 7a by the power failure detection means 5a. In response to the detection signal, only the discharge lamp La3 of the backlight BL is turned on, and only the liquid crystal panel driver 24 of the liquid crystal panel drivers 23 and 24 is controlled to operate. Accordingly, the display area of the present liquid crystal display device is only the area of the liquid crystal panel in which the discharge lamp La3 is disposed immediately below the entire display area and the liquid crystal panel driver 24 is driven.

  Next, the effect of the liquid crystal display device of the present embodiment will be described. In an emergency where the standby power supply is an input power source, only a part of the entire screen of the liquid crystal display device becomes a display region. The power can be reduced, and the drive time of the display device by the standby power supply device can be extended.

(Embodiment 6)
FIG. 11 shows a system configuration diagram of the liquid crystal display device of the present embodiment. The standby power supply device 7a in the liquid crystal display device of the fifth embodiment is a direct current power supply. However, in the liquid crystal display device of the present embodiment, the standby power supply device 7b is assumed to be an alternating current power supply. However, when the standby power supply 7b is an AC power supply, it cannot be distinguished from the commercial power supply AC that is also an AC power supply, and a power failure detection means 5a connected to the power supply line detects a power failure as shown in the fifth embodiment. Can not do it. Therefore, in the liquid crystal display device of the present embodiment, the power failure detection means 5b receives a signal indicating the operation state from the standby power supply device 7b and determines the power failure.

  Next, the effect of the liquid crystal display device of the present embodiment will be described. Even when the standby power supply 7b, which is an AC power supply, is used as an emergency input power supply, a power failure detection means 5b is received in response to a signal from the standby power supply 7b. Can be used to determine the power outage.

It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 1 of this invention. It is a disassembled perspective view which shows the structure of the liquid crystal display device of Embodiment 1 of this invention. FIG. 2 is an operation explanatory diagram of Embodiment 1 of the present invention, (A) is an explanatory diagram of a backlight operation in an emergency, (B) is an explanatory diagram of a display area in an emergency, and (C) and (D) are emergency. It is explanatory drawing which shows the example of the display content in. It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 2 of this invention. It is a disassembled perspective view which shows the structure of the liquid crystal display device of Embodiment 3 of this invention. It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 3 of this invention. It is operation | movement explanatory drawing of Embodiment 3 of this invention, (A) is explanatory drawing of the backlight operation | movement in emergency, (B) is explanatory drawing of the display area in emergency. It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 4 of this invention. It is operation | movement explanatory drawing of Embodiment 4 of this invention, (A) is explanatory drawing of the display area at the time of earthquake occurrence, (B) is explanatory drawing which shows the example of the display content at the time of fire outbreak. It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 5 of this invention. It is a block circuit diagram which shows the circuit structure of the liquid crystal display device of Embodiment 6 of this invention.

Explanation of symbols

1 to 3 lighting circuit 5 power failure detection means AC commercial power supply Vdc emergency power supply La1 to La3 discharge lamp Q1, Q2 switching means

Claims (9)

A display device that functions by power supply from a commercial power supply at all times, and functions by power supply from an emergency power supply in an emergency, comprising a power failure detection means for detecting a power failure of the commercial power supply, and a power failure detection signal from the power failure detection means And a means for switching so that only a part of the entire display screen is displayed. 2. The display device according to claim 1, wherein the emergency power source is a battery, and switches between the commercial power source and the battery in response to a detection signal from the power failure detection means. 3. The display according to claim 1, further comprising an emergency signal receiving unit that receives an emergency signal from the outside, wherein the power failure detection means detects a power failure and the emergency signal reception unit receives the emergency signal. A display device that performs display corresponding to emergency signal information in a partial area of a screen. 4. The display device according to claim 1, wherein the power failure detection means detects a power failure in response to a signal from the emergency power source. 5. The backlight according to claim 1, comprising a backlight composed of a plurality of light sources, wherein the plurality of light sources irradiate only the first light source group that irradiates only a partial region of the display screen and the other region. Each of the light source groups is provided with a lighting device, and when a power failure is detected by the power failure detection means, only the lighting device of the first light source group is the emergency power source. A display device characterized in that the first light source group is turned on in response to power supply from the power source. 6. The liquid crystal panel according to claim 5, a first liquid crystal panel driver for driving a liquid crystal panel in a region irradiated with a first light source group among the plurality of light sources, and a liquid crystal panel in a region irradiated with a second light source group A second liquid crystal panel driver for driving the power supply, and when a power failure is detected by the power failure detection means, only the first liquid crystal panel driver is operated by receiving power from the emergency power supply. Characteristic display device. 7. The display device according to claim 5, wherein when a power failure is detected by the power failure detection means, the first light source group blinks and lights up at a period of a critical flicker frequency or more. The display device according to claim 5, wherein a light source of the backlight is a discharge lamp or a light emitting diode, and includes a direct-type backlight unit configured using them. The display device according to claim 5, wherein a light source of the backlight is a discharge lamp or a light emitting diode, and includes a sidelight type backlight unit configured using them.

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