JP2011118286A - Liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display apparatus the luminous efficiency of which is improved, the power consumption of which is reduced without lowering the luminance thereof, the dynamic range of which is widened drastically and the service life of whose hot cathode fluorescent lamp is restrained from be deteriorated. <P>SOLUTION: A backlight of a liquid crystal panel includes a plurality of hot cathode fluorescent lamps and a light emitting diode array. A light emitter is changed over and driven according to the luminance and the ambient temperature or by the selection of a user to reduce the power consumption while improving the image quality. The illuminance of the hot cathode fluorescent lamp is lowered to prolong the service life thereof. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that performs power-saving backlight driving with improved image quality.

  For example, liquid crystal display devices are widely used as display means for various information terminal monitors such as mobile phones and personal computers, or television receivers. This type of liquid crystal display device is for visualizing an image formed on a liquid crystal panel by irradiating light. Some small information devices use ambient light as a light source for visualization, but in order to display a good image regardless of the ambient light state or on a relatively large screen, a liquid crystal panel is used. In many cases, the illumination light source includes an illumination light source called a backlight installed on the back surface of the liquid crystal panel, and an image formed on the liquid crystal panel is irradiated with illumination light from the illumination light source.

There are roughly two types of backlights. One is a side-edge type backlight used for a monitor or the like in which the depth of the device is limited. The other is a direct-type backlight installed directly under the back of the liquid crystal panel in a relatively large monitor or television receiver that requires high luminance.
Patent Document 1 discloses a gallium nitride-based light emitting element as a conventional example of this type of direct type backlight.
In Patent Document 2, a temperature sensor is provided in the vicinity of the backlight, and when the temperature near the backlight is low, the driving ratio of the cold cathode fluorescent lamp is increased, and when the temperature in the vicinity is high, the driving ratio is decreased. A technique for improving the rise of brightness and suppressing the decrease in brightness at room temperature to extend the life of the cold cathode fluorescent lamp is disclosed.

Japanese Patent Laid-Open No. 11-8437 Japanese Patent Laid-Open No. 9-288262

  As described above, the liquid crystal display device adopting the cold cathode fluorescent lamp has a slow response to the rise of the lamp brightness in a low temperature environment, and therefore, it is difficult to follow the optimal dimming control in real time and is continuous. In bright scenes, the luminous efficiency decreases as the temperature of the lamp and the surrounding area rises, the brightness gradually decreases, and the power consumption for a given brightness also increases. In these environments, the life of the lamp itself is increased. There was a problem of shortening.

  Further, the method disclosed in Patent Document 2 increases the ON ratio of the lighting drive circuit of the cold cathode lamp when the temperature is low, and conversely reduces the ON ratio of the cold cathode fluorescent lamp when the temperature is high. Although it can be extended, there is a problem not only with stability of image quality and deterioration of lamp life but also with increased power consumption due to switching of the lighting ratio of the lamp. There is still a gap.

  It is an object of the present invention to provide a liquid crystal display device that solves the problems of the prior art and performs power-saving backlight driving with improved image quality.

  In order to achieve the above object, the present invention provides a liquid crystal display device that displays an image by irradiating a backlight to a liquid crystal panel, and supplies a hot cathode fluorescent lamp for supplying the backlight and the backlight. It has the light-emitting-diode array for doing.

  The present invention also provides a liquid crystal display device that displays an image by irradiating a backlight to a liquid crystal panel, and is supplied with a video luminance signal inputted for display on the liquid crystal display device, and brightness of the video luminance signal A brightness detection circuit for detecting the brightness, a control calculation circuit for generating a brightness control signal for controlling the brightness of the backlight based on the brightness of the video brightness signal detected by the brightness detection circuit, and the control calculation circuit And a light emitting diode array for supplying the backlight based on the luminance control signal generated by the control arithmetic circuit. .

  According to the present invention, it is possible to realize a liquid crystal display device that can drive a power-saving backlight with improved image quality, and it is possible to contribute to improving the performance of the liquid crystal display device.

1 is a first basic configuration diagram showing a backlight of a liquid crystal display device according to an embodiment of the present invention. It is a 2nd basic block diagram which shows the backlight of the liquid crystal display device in one Example of this invention. It is a circuit block diagram of the liquid crystal display device in one Example of this invention. It is a 1st time chart which shows the light emission luminance in the 1st Embodiment of this invention. It is a 2nd time chart which shows the light emission luminance in the 1st Embodiment of this invention. It is a figure which shows the relationship between the light-emitting luminance and ambient temperature in the 2nd Embodiment of this invention. It is a figure which shows the relationship between the light-emitting luminance and the horizontal direction position in the 3rd Embodiment of this invention. It is a 1st time chart which shows the power consumption in the 4th Embodiment of this invention. It is a 2nd time chart which shows the power consumption in the 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, parts having common functions are denoted by the same reference numerals, and those that have been described once are not described repeatedly in order to avoid complicated description.

  FIG. 1 is a first basic configuration diagram showing a backlight of a liquid crystal display device according to an embodiment of the present invention. The backlight according to the present embodiment has one feature in that a plurality of hot cathode fluorescent lamps 4 and a plurality of light emitting diode arrays 7 arranged in parallel inside are installed. Here, two hot cathode fluorescent lamps 4 and a plurality of light emitting diodes 7 are arranged as an array. The light emitting diode 7 can be substantially white by combining RGB light emitting diode arrays. In the following description, the light emitting diode array may be simply described as a light emitting diode or LED.

  The two hot cathode fluorescent lamps 4 are connected to the lamp driving circuit 5, and the light emitting diode array 7 is connected to the LED driving circuit 6, and the light emitted from each is radiated into the light guide plate 8. Has been. Here, in the drawing, a diffusion plate 10 is installed on the upper side of the light guide plate 8 and a reflection plate 9 is installed on the lower side. That is, FIG. 1 shows the above-described side edge type backlight, with the image display portion facing upward. In this case, the light emitted from the hot cathode fluorescent lamp 4 and the light emitting diode array 7 is incident on the light guide plate 8 and propagates in the plane direction inside the light guide plate 8. Thereafter, the light is reflected from the boundary surface of the reflecting plate 9 with the light guide plate 8 and then irradiated to the inside of the diffusing plate 10 to become uniform light in the surface direction, and the liquid crystal provided on the upper side of the diffusing plate 10 in the drawing. (Not shown) is emitted as illumination light. The contact surface between the light guide plate 8 and the reflection plate 9 forms, for example, a wedge-shaped curved surface so that the above-described light is reflected as uniformly as possible in the surface direction of the light guide plate 8.

  FIG. 2 is a second basic configuration diagram showing the backlight of the liquid crystal display device in one embodiment of the present invention. The case of the direct type backlight described above is shown. FIG. 2 is different from FIG. 1 in that the image display portion is drawn diagonally toward the right side on the drawing. The hot-cathode fluorescent lamp 4 and the light-emitting diode array 7 of this embodiment are driven and controlled by a drive circuit to be described later, and the backlight light quantity control according to the brightness of the video signal displayed on the liquid crystal panel is controlled at high speed. High-speed response of video brightness can be realized without increasing power consumption. On the back side of the light guide plate 8 in the drawing, a reflection plate 9 is installed with the hot cathode fluorescent lamp 4 and the light emitting diode array 7 interposed therebetween. Light from the hot-cathode fluorescent lamp 4 or the light-emitting diode array 7 driven by alternating current enters the light guide plate 8. The incident light is emitted as illumination light in the direction of the liquid crystal panel (not shown) from the front diffusion plate 10 in the drawing while propagating through the inside of the light guide plate 8.

  Next, an embodiment of the present invention will be described in detail with reference to FIGS. By selecting and automatically controlling either or both of the hot cathode fluorescent lamp 4 and the light emitting diode array 7, the user can select the backlight according to the viewing environment, and at the same time, the power of the backlight can be reduced. One feature is that the liquid crystal display device and its drive circuit can be configured. That is, the hot cathode fluorescent lamp 4 has high illuminance, but has a relatively short life and high power consumption. On the other hand, the light emitting diode array 7 has a slightly low illuminance, but has a long lifetime and low power consumption for obtaining a constant illuminance. The aim of this embodiment is to reduce the power consumption, extend the life of the hot cathode fluorescent lamp 4 and improve the image quality of the displayed image by making use of the advantages of both according to the situation of use. is there.

FIG. 3 is a circuit block diagram of the liquid crystal display device according to one embodiment (first embodiment) of the present invention.
The present embodiment is a liquid crystal display device provided with drive circuits 13 and 21 for detecting the characteristics of a video signal and controlling the hot cathode fluorescent lamp 4 and the light emitting diode array 7 of the backlight. In FIG. 3, this liquid crystal display device has a side edge type backlight having a hot cathode fluorescent lamp 4 and a light emitting diode array 7 on a liquid crystal panel (LCD panel) 14. The hot cathode fluorescent lamp 4 and the light emitting diode array 7 in FIG. 3 are schematically shown as one each.

A video signal (image display signal) is supplied from the video input processing circuit 18 to the LCD panel controller 17. The video input processing circuit 18 includes a contrast control circuit 18A, a DC level control circuit 18B, and a digital γ correction circuit 18C.
The liquid crystal panel 14 includes an LCD driver (column side) 15 and an LCD driver (row side) 16 that are driven by an LCD panel controller 17.

The hot cathode fluorescent lamp 4 is AC-driven by a lighting circuit (also called a fluorescent lamp driving circuit or an inverter) 13 and supplied with a low-power driving current. The lighting circuit 13 corresponds to the lamp driving circuit 5 of FIG. 1, but has a new feature that the lighting circuit 13 is controlled by the control arithmetic circuit 20 in accordance with the image to be displayed and the surrounding environment.
On the other hand, the light emitting diode array 7 is supplied with a dimming signal via a lighting circuit (also referred to as an LED driving circuit or a light emitting diode driving circuit) 21. The lighting circuit 21 corresponds to the light-emitting diode driving circuit 6 of FIG. 1, but has a new feature that the lighting circuit 21 is controlled by the control arithmetic circuit 20 in accordance with the image to be displayed and the surrounding environment.

  A control arithmetic circuit 20 that generates a dimming signal according to the video signal is connected to the light emitting diode drive circuit 21. The control arithmetic circuit 20 has an image quality control circuit 20A and a backlight luminance control circuit 20B. The control detection circuit 20 is supplied with the following detection signal from the brightness detection circuit 19 of the video signal.

  The brightness detection circuit 19 includes an APL detection circuit 19A, a MAX luminance detection circuit 19B, and a MIN luminance detection circuit 19C. The video signal input from the external circuit is input to the APL detection circuit 19A and the average luminance level (Average Picture Level) is detected. The MAX luminance detection circuit 19B and the MIN luminance detection circuit 19C each have the maximum video luminance signal. Detect value and minimum value. The average luminance level, the maximum luminance value, and the minimum luminance value detected by the brightness detection circuit 19 are input to the image quality control calculation circuit 20A, and the image quality control amount is calculated.

  The image quality control amount calculated by the image quality control calculation circuit 20A of the control / arithmetic circuit 20 is supplied to the luminance backlight control circuit 20B, generates an optimal dimming signal, and passes through the light emitting diode drive circuit 21 to the light emitting diode array 7. Applied. In accordance with the dimming signal related to the luminance of the video signal to be displayed, the light emitting diode array 7 is dimmed at high speed.

  The image quality control amount calculated by the image quality control circuit 20A of the control / arithmetic circuit 20 is applied to the contrast control circuit 18A and the DC level control circuit 18B of the previous image quality control circuit 18. The contrast control circuit 18A and the DC level control circuit 18B control the contrast and DC level of the video display signal to optimum values that are preferably displayed visually according to the input image quality control amount.

  A technique for controlling the contrast and DC level of a video to be displayed with reference to the average value, maximum value, and minimum value of a video luminance signal to be displayed is known. In this embodiment, the average value, maximum value, and minimum value are known. One feature is that the backlight is further controlled.

The hot-cathode fluorescent lamp 4 is normally AC-driven by the lighting circuit 13 regardless of the change in the luminance of the video display signal, for example, with a low current with a margin sufficient to obtain the average luminance level of the video signal.
When the user selects the power saving mode according to the user's specification, only the light emitting diode array 7 is driven. Further, when the user selects the high luminance mode, the light emitting diode is driven simultaneously with the hot cathode fluorescent lamp 4. It is also possible to control the luminance to increase with the light amount of the array 7.

Alternatively, when the illuminance of the hot cathode fluorescent lamp 4 decreases and when the illuminance of the hot cathode fluorescent lamp 4 falls below a specified value, that is, when the remaining lifetime is small, or the ambient temperature is low and the illuminance of the hot cathode fluorescent lamp 4 is low. In this case, only the light emitting diode array 7 is driven. These can also be implemented by detecting the illuminance and temperature in the LCD panel 14 using the illuminance sensor circuit 22A and the temperature sensor circuit 22B and supplying them to the image quality control circuit 20A.
Therefore, according to the present embodiment, the power of the lighting circuit 13 that is a driving power source of the hot cathode lamp 4 that requires AC driving can be reduced by the user's selection, so that the amount of heat generation is reduced, resulting in a temperature rise. Deterioration of the hot cathode lamp itself is suppressed, and a longer life can be achieved.

Further, only when the video signal exceeds a certain threshold value, the hot cathode lamp 4 and the light emitting diode array 7 can be turned on at the same time. The light emitting diode array 7 emits light in the characteristics obtained only by the hot cathode lamp 4. Needless to say, the peak intensity characteristic can be added.
Further, the color γ characteristic of the liquid crystal panel is set to a value that can improve the color reproducibility depending on each lighting mode when the light emitting diode array 7 alone or the light emitting diode array 7 and the hot cathode fluorescent lamp 4 are simultaneously turned on. Therefore, high image quality performance can be realized under any lighting conditions.

  According to the embodiment described above, the amount of light of the backlight is controlled at high speed according to the brightness of the video signal, the luminous efficiency of the hot cathode fluorescent lamp 4 can be improved, and the power consumption can be reduced. In addition, by controlling the light emission of the light emitting diode array 7, the dynamic range of the backlight is expanded to widen the entire dynamic range, or the illuminance of the hot cathode fluorescent lamp 4 is lowered according to the illuminance of the light emitting diode array 7. The life of the hot cathode fluorescent lamp 4 can be extended.

FIG. 4 is a first time chart showing the light emission luminance in the first embodiment of the present invention, and using both the hot cathode fluorescent lamp 4 and the light emitting diode array 7 as a backlight of the liquid crystal display device, An example is shown in which the emission luminance (vertical axis in the figure) is controlled with time (horizontal axis in the figure).
The same reference numerals as those of the embodiments correspond to the same functional parts. In this embodiment, a combination of the hot cathode lamp 4 and the light-emitting diode array 7 described in FIG. 3 is used as the light source of the backlight, and the circuit configuration shown in FIG. 3 is used as its drive circuit. .

  When only the light emitting diode array 7 is driven (period A in the figure), the power source of the lighting circuit 13 of the hot cathode fluorescent lamp 4 is turned off. Similarly, when only the hot cathode fluorescent lamp 4 is driven (period B in the figure), the power source of the lighting circuit 21 of the light emitting diode array 7 is turned off. In other words, when the power supplied to the lighting circuit 13 of the hot cathode fluorescent lamp 4 is not used, the power consumption can be further reduced by cutting the power supply and suppressing the minute power.

  FIG. 5 is a second time chart showing the light emission luminance in the first embodiment of the present invention, and shows an example in which only the light emitting diode array 7 is used. In this case, as shown in the figure, the power supply from the lighting circuit 13 of the hot cathode fluorescent lamp 4 is cut (off) and driven by the light emitting diode array 7 alone.

FIG. 4 corresponds to the case where control according to the brightness around the liquid crystal display device is performed, for example. At night when the surroundings are relatively dark, the brightness of the display image is not required so much, so that only the light emitting diode array 7 is turned on as the backlight as in the period A. On the other hand, since the brightness of the display image is necessary during the daytime, the hot cathode fluorescent lamp 4 is turned on as a backlight as in the period B. Of course, both the hot cathode fluorescent lamp 4 and the light emitting diode array 7 may be turned on during the daytime. In this way, power consumption at night can be reduced, and high-quality images can be displayed during the day without being disturbed by ambient light.
When the illuminance of the hot cathode fluorescent lamp 4 changes due to a change in ambient temperature or deterioration during use due to the lifetime, the illuminance is switched to the light emitting diode array 7 during the period B or the hot cathode fluorescent light is changed according to the change. Both the lamp 4 and the light emitting diode array 7 are preferably turned on.

FIG. 5 is applicable when the liquid crystal display device is always installed in a dark place such as a bedroom. That is, when not much brightness is required, current consumption can be reduced by always lighting only the light emitting diode array 7.
Further, as described above, when the illuminance of the hot cathode fluorescent lamp 4 is low due to the low ambient temperature or the short remaining life, it is preferable to always turn on only the light emitting diode array 7 as shown in FIG.

  Either of FIG. 4 and FIG. 5 may be switched manually by the user. Further, for example, the illuminance of the hot cathode fluorescent lamp 4 may be detected and automatically switched using the illuminance sensor circuit 22A shown in FIG. Similarly, the brightness around the liquid crystal display device may be detected by an illuminance sensor circuit and automatically switched.

FIG. 6 is a diagram showing the relationship between the light emission luminance and the ambient temperature in the second embodiment of the present invention. The light emission luminance of the backlight of the liquid crystal display device according to the ambient temperature (horizontal axis in the drawing) An example of controlling the vertical axis) is shown.
The same reference numerals as those of the embodiments correspond to the same functional parts. In this embodiment, a combination of the hot cathode lamp 4 and the light emitting diode array 7 described in FIG. 3 detects the temperature of the LCD panel 14 and supplies temperature information to the image quality control circuit 20A. Based on this, the control arithmetic circuit 20 controls the backlight as follows, for example.

  First, when the temperature is as low as 15 degrees (Celsius) or lower and as high as 35 degrees or higher, the luminous efficiency of the hot cathode lamp 4 is low, so that only the light emitting diode array 7 is lit to reduce the current consumption. Since the luminous efficiency of the hot cathode lamp 4 is high between 15 degrees and 35 degrees, only the hot cathode lamp 4 is turned on so that a bright backlight can be obtained. Alternatively, either the hot cathode lamp 4 or the light emitting diode array 7 can be selected. This may be switched manually by the user as in FIG. 4, or may be switched automatically by providing, for example, a temperature sensor circuit 22B. An illuminance sensor circuit 22A may be provided to detect the illuminance of the hot cathode lamp 4 and switch automatically.

  In either case, when the remaining life of the hot cathode lamp 4 is reduced, only the light emitting diode array 7 is driven. Each time the power is turned on, the liquid crystal display device displays a fluorescent lamp replacement mark or the like that can determine that the hot-cathode fluorescent lamp is at the end of its life, presents information on lamp replacement to the user, and drives only the light-emitting diode array 7. .

FIG. 7 is a diagram showing the relationship between the light emission luminance and the horizontal position in the third embodiment of the present invention, and shows an example used to improve the alignment characteristics of the liquid crystal display device.
In the orientation characteristics of the hot cathode lamp 4, there is a tendency that the remaining life is reduced and the light emission characteristics around the tube are rapidly lowered. In order to improve this, the present embodiment is characterized in that the light emitting characteristics are improved by lighting the light emitting diode array 7 in the peripheral portion. That is, the light emitting diode array 7 is turned on to compensate for the decrease in brightness of the hot cathode lamp 4 in the peripheral portion, and only the hot cathode lamp 4 is turned on in the center portion if the decrease in brightness of the hot cathode lamp 4 is not a problem. Let Thereby, it is possible to compensate for the deterioration of the image quality due to the life of the hot cathode lamp 4.

FIGS. 8 and 9 are first and second time charts showing power consumption in the fourth embodiment of the present invention, and showing an example of switching the lighting circuit of the liquid crystal display device depending on the case. .
This embodiment is characterized in that switching is performed according to the content for displaying the light source of the backlight. That is, in FIG. 8, when watching a relatively short news program broadcasted on the A channel, for example, about one hour, the light emitting diode array 7 is used as a backlight. Thereby, power consumption can be reduced even if the brightness is slightly dark. In addition, when viewing a relatively long entertainment program of about 2 hours broadcast on the B channel, the hot cathode fluorescent lamp 4 is used as a backlight. Thereby, an entertainment program can be enjoyed with a bright image. Switching for this may be performed manually by the user, or may be switched automatically by determining the type of program on the liquid crystal display device side.

  In FIG. 9, the commercial (CM) is switched to the light emitting diode array 7 during broadcasting, and the program content is switched to the hot cathode fluorescent lamp 4 during broadcasting to be used as a backlight. Accordingly, an image with a relatively low priority can be displayed with priority on reducing power consumption, and an image with a high priority can be displayed with priority on brightness. Switching for this purpose may be performed manually by the user, but since a technique for automatically determining a commercial is known, it may be switched automatically by determining a commercial on the liquid crystal display device side.

  4, 6, 8, and 9, when the hot cathode fluorescent lamp 4 is turned on and used as a backlight, the light emitting diode array 7 may be turned on at the same time. In this case, as described above, the dynamic range of the backlight can be expanded, or the lifetime of the hot cathode fluorescent lamp 4 can be reduced by reducing the illuminance of the hot cathode fluorescent lamp 4 according to the illuminance of the light emitting diode array 7. Can be extended.

  According to the embodiment described above, the light intensity control of the backlight is controlled at high speed according to the brightness and temperature of the surroundings or the brightness and contents of the video signal, so that the light emission efficiency can be improved and the power consumption can be reduced. When necessary, a bright high-quality image can be obtained. In addition, by controlling the light emission of the light emitting diode array, the dynamic range of the backlight can be expanded to widen the entire dynamic range, and the life of the hot cathode fluorescent lamp can be extended.

  The embodiments described above are not intended to limit the present invention. Different examples are conceivable in the circuit block diagram of FIG. 3, and application examples other than the examples shown in FIGS. 4 to 9 are conceivable, all of which fall within the scope of the present invention.

  4: hot cathode fluorescent lamp, 5: lamp driving circuit, 6: light emitting diode driving circuit, 7: light emitting diode array, 8: light guide plate, 9: reflecting plate, 10: diffuser plate, 11: lamp reflecting sheet, 14: LCD Panel, 15: LCD driver, 17: LCD panel controller.

Claims (8)

A liquid crystal display device that displays an image by irradiating a backlight to a liquid crystal panel,
A hot cathode fluorescent lamp for supplying the backlight;
A liquid crystal display device comprising: a light emitting diode array for supplying the backlight. A liquid crystal display device that displays an image by irradiating a backlight to a liquid crystal panel,
A brightness detection circuit that is supplied with an input video luminance signal for display on the liquid crystal display device and detects the brightness of the video luminance signal;
A control arithmetic circuit for generating a luminance control signal for performing luminance control of the backlight based on the brightness of the video luminance signal detected by the brightness detection circuit;
A hot cathode fluorescent lamp for supplying the backlight based on a luminance control signal generated by the control arithmetic circuit;
A liquid crystal display device comprising: a light emitting diode array that supplies the backlight based on a luminance control signal generated by the control arithmetic circuit. The liquid crystal display device according to claim 2,
An illuminance sensor circuit for detecting the illuminance of the backlight in the liquid crystal panel;
A temperature sensor circuit for detecting a temperature in the liquid crystal panel;
The control arithmetic circuit is
A liquid crystal display device that generates a luminance control signal for performing luminance control of the backlight based on the illuminance detected by the illuminance sensor circuit or the temperature detected by the temperature sensor circuit. The liquid crystal display device according to claim 3.
The control arithmetic circuit is
Based on the temperature detected by the temperature sensor circuit, the backlight emits light from the light emitting diode array at a low temperature, and the backlight is the hot cathode fluorescent lamp or the hot cathode fluorescent lamp and the light emitting diode at a temperature higher than a predetermined temperature. A liquid crystal display device generating a luminance control signal for controlling the hot cathode fluorescent lamp and the light emitting diode array so that both of the arrays emit light. The liquid crystal display device according to claim 3.
The control arithmetic circuit is
Based on the illuminance detected by the illuminance sensor circuit, when the illuminance of the hot cathode fluorescent lamp is lower than a predetermined value, the backlight emits the light emitting diode array so that the backlight emits light. A liquid crystal display device characterized by generating a luminance control signal for controlling the brightness. The liquid crystal display device according to claim 2,
The user selects whether the hot cathode fluorescent lamp emits light from the backlight, the light emitting diode array emits light, or both the hot cathode fluorescent lamp and the light emitting diode array emit light. A liquid crystal display device. The liquid crystal display device according to claim 3.
The control arithmetic circuit is
When the illuminance irradiated by the hot cathode fluorescent lamp detected by the illuminance sensor circuit is lower than the central portion of the liquid crystal panel in the peripheral portion of the liquid crystal panel,
The liquid crystal display device according to claim 1, wherein a luminance control signal for controlling the light emitting diode array is generated so that the illuminance of the peripheral portion of the liquid crystal panel is compensated by the light emitting diode array. The liquid crystal display device according to claim 2,
The control arithmetic circuit is
A liquid crystal display device that generates a luminance control signal for controlling the hot cathode fluorescent lamp and the light emitting diode array based on video content input to the liquid crystal display device.

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