WO2013125073A1

WO2013125073A1 - Backlight light source, backlight device, liquid crystal display device, and method for controlling lighting of backlight light source

Info

Publication number: WO2013125073A1
Application number: PCT/JP2012/071911
Authority: WO
Inventors: 仁米田; 守高谷
Original assignee: シャープ株式会社
Priority date: 2012-02-20
Filing date: 2012-08-29
Publication date: 2013-08-29
Also published as: JP2013171149A

Abstract

The purpose of the present invention is to prevent a DC/DC converter and the periphery thereof from being heated to a high temperature. A lighting timing determination unit (21) can switch between a first mode in which the reference points in time for at least either turning on or turning off of LEDs are different for each line in an LED matrix, and a second mode in which the reference points in time for at least either turning on or turning off of LEDs correspond to each other for at least two lines in the LED matrix and the reference points in time do not correspond between the two lines and the other lines. When the temperature of the DC/DC converter exceeds a prescribed value, the lighting timing determination unit (21) switches to the second mode that is a heat generation reduction mode.

Description

Backlight light source, backlight device, liquid crystal display device, and lighting control method for backlight light source

The present invention relates to a backlight light source provided corresponding to one of a plurality of display areas obtained by dividing one display screen (hereinafter also referred to as “screen”) in a liquid crystal panel. The present invention also provides a backlight device including a plurality of backlight light sources provided corresponding to each of the plurality of display areas, a liquid crystal display device including the backlight device, and a backlight light source. The present invention relates to a lighting control method.

In a liquid crystal display device, a technique called local dimming (also referred to as local dimming) is known as a technique for improving the contrast of an image displayed on a screen. Local dimming is a technique for controlling the brightness of lighting by a backlight device composed of, for example, LEDs (Light Emitting Diodes) for each of a plurality of display areas obtained by dividing the screen.

In addition, as a technique for reducing blurring of a moving image displayed on a screen in local dimming, Japanese Patent Application Laid-Open No. 2004-228561 discloses that a backlight light source corresponding to the display area is turned on after the rewriting of the image in the display area responds. Techniques for making them disclosed are disclosed.

Specifically, the liquid crystal display device disclosed in Patent Document 1 is divided into a liquid crystal panel having a divided portion in which the entire area of the screen is divided into a plurality of divided portions corresponding to the divided portions of the liquid crystal panel. And a rear light source having a divided portion. Then, the divided portion of the back light source corresponding to the divided portion of the liquid crystal panel during the response transition is turned off. As a result, in the technique disclosed in Patent Document 1, the moving image generated due to the obscuration of the screen in the region of the liquid crystal panel during the response transition and the hold characteristic by the TFT (Thin Film Transistor). It becomes possible to improve the deterioration of.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2000-275605 (October 6, 2000)”

FIG. 6 is a diagram illustrating a configuration example of main parts of a backlight device and a backlight light source that are conventionally provided in a local dimming liquid crystal display device.

In FIG. 6, as the above configuration example, a backlight device and a backlight light source that illuminate a liquid crystal panel (not shown) in which the screen is divided into a total of eight display areas (2 horizontal × 4 vertical). The structure of is shown.

The backlight device 70 shown in FIG. 6 includes eight backlight light sources 711L to 714L and 711R to 714R. The backlight light sources 711L to 714L and 711R to 714R are arranged to form a matrix and correspond to the eight display areas on a one-to-one basis. The backlight sources 711L to 714L and 711R to 714R each illuminate one corresponding display area and can be lit independently of each other.

Then, according to the image displayed on the screen, the backlight light sources 711L to 714L and 711R to 714R are turned on independently of each other, so that the brightness of lighting by the backlight device 70 is set for each of the eight display areas. It becomes possible to control.

Further, the backlight light source 711L includes LEDs A1, A2, A3,..., LEDs B1, B2, B3,..., And LEDs C1, C2, C3,. For convenience of illustration, FIG. 6 shows only a total of nine LEDs (3 horizontal x 3 vertical), and the other LEDs are not shown. However, in practice, it is general that four or more LEDs are provided horizontally, and four or more LEDs may be provided vertically.

The backlight light source 711L further includes a DC / DC (direct current-direct current) converter 72 and an LED drive circuit 73.

LEDA1, A2, A3,..., LEDB1, B2, B3,..., And LEDC1, C2, C3,. Is connected to the LED drive circuit 73.

Further, LEDA1, A2, A3,..., LEDB1, B2, B3,..., And LEDC1, C2, C3,. That is, the LEDs A1, A2, A3,... Are arranged in a row horizontally. The same applies to LEDs B1, B2, B3,... And LEDs C1, C2, C3,. Moreover, LEDA1, B1, and C1 are arranged vertically, LEDA2, B2, and C2 are arranged vertically, and LEDA3, B3, and C3 are arranged vertically. The same applies to other LEDs not shown.

The DC / DC converter 72 steps down the applied voltage, and converts the current obtained from the stepped down voltage into LEDA1, A2, A3,..., LEDB1, B2, B3,. To C3,. .., LEDB1, B2, B3,..., And LEDs C1, C2, C3,... Are turned on by the current supplied from the DC / DC converter 72.

The LED drive circuit 73 controls whether or not the LEDs A1, A2, A3,..., The LEDs B1, B2, B3,..., And the LEDs C1, C2, C3,. Thus, these LEDs are driven to control lighting by the backlight light source 711L. Thereby, local dimming can be realized.

FIG. 7 is a diagram illustrating a configuration example of the LED drive circuit 73.

The LED drive circuit 73 includes a lighting timing determination unit 81.

The lighting timing determination unit 81 determines the lighting timing (lighting and extinguishing timing) of the LED included in the backlight light source 711L based on the lighting reference position information and the lighting period width information, and selects the LED according to the lighting timing. Light up. The lighting timing determination unit 81 performs the determination and lighting of the lighting timing for all LEDs included in the backlight light source 711L.

The lighting reference position information is information indicating a timing that is a reference of timing for determining each lighting timing and lighting each LED to be lit.

The lighting reference position information is the same information among the LEDs A1, A2, A3,..., The same information between the LEDs B1, B2, B3,..., And the same between the LEDs C1, C2, C3,. It becomes information of. Further, the lighting reference position information is in the order of the lighting timing of LEDs A1, A2, A3,..., The lighting timing of LEDs B1, B2, B3,..., And the lighting timing of LEDs C1, C2, C3,. It becomes information that the lighting timing of the LED comes.

Also, in order to reduce the blurring of the moving image displayed in the display area, it is necessary to turn on the LED in order from the one that illuminates the place where the image rewriting response is completed in the display area. In many cases, the lighting reference position information indicates a timing at which the lighting of the LED is terminated as the reference timing. However, the lighting reference position information may indicate a timing at which the lighting of the LED is started as the reference timing.

The lighting period width information is information indicating a period (width) during which each of the LEDs to be lit and the lighting timing is turned on.

The lighting period width information is independent information for all the LEDs provided in the backlight light source 711L, and is updated for each frame of the image. Note that the period during which the LED is lit, which is indicated by the lighting period width information, differs depending on whether the LED is lit brightly or darkly. The longer the LED is lit, the brighter the LED is lit.

Here, as described above, the timing for ending the lighting of the LED is determined based on the lighting reference position information. For this reason, the lighting period width information is information that changes the timing of starting the lighting of the LED according to the period of lighting the LED so that the lighting of the LED can be terminated at the timing.

As a result, the lighting timing determination unit 81 first determines each LED constituting a row (hereinafter also referred to as “A row”) composed of LEDs A1, A2, A3,... Based on the lighting reference position information. Light up until timing. After the timing of ending the lighting of the respective LEDs constituting the A row, the lighting timing determining unit 81 constitutes each row constituting the rows (hereinafter also referred to as “B row”) composed of LEDs B1, B2, B3,. The LED is lit up to a predetermined timing based on the lighting reference position information. After the timing of ending the lighting of the LEDs constituting the B row, the lighting timing determining unit 81 constitutes a row (hereinafter also referred to as “C row”) composed of the LEDs C1, C2, C3,. The LED is lit up to a predetermined timing based on the lighting reference position information. In addition, all the rows A, B, and C are lit up to the predetermined timing corresponding to the individual periods in the individual rows based on the lighting period width information.

Here, a case is considered in which the periods during which the LEDs A1, A2, A3, the LEDs B1, B2, B3, and the LEDs C1, C2, C3 are lit are determined as shown in the table of FIG. .

FIG. 8 is a table showing the relationship between the LED to turn on the backlight light source 711L and the lighting period. In addition, about the LED which is not displayed in the table | surface shown in FIG. 8, the period to light is assumed to be 0 (it is not lighted).

FIG. 9 is a timing chart when the LED is turned on according to the table shown in FIG.

In the timing chart shown in FIG. 9, the dark-colored portion of the band indicates a state where the corresponding LED is lit, and the portion where the band is colorless indicates a state where the corresponding LED is turned off. . In the timing chart, one section obtained by dividing the time axis (horizontal axis) by two adjacent broken lines indicates one unit period, which corresponds to the lighting period “5” in the table shown in FIG.

For LEDs A1, A2, and A3, the end point of the fourth unit period is set as the lighting end timing based on the lighting reference position information (see the lighting reference position in row A in FIG. 9). Each of the LEDs A1, A2, and A3 is lit for the lighting period determined by the lighting period width information until the timing.

For LEDs B1, B2, and B3, the end point of the eighth unit period is the end timing of lighting based on the lighting reference position information (see the lighting reference position of row B in FIG. 9). Each of the LEDs B1, B2, and B3 is lit for the lighting period determined by the lighting period width information until the timing.

For LEDs C1, C2, and C3, the end point of the twelfth unit period is set as the lighting end timing based on the lighting reference position information (see the lighting reference position in row C in FIG. 9). Each of the LEDs C1, C2, and C3 is lit for the lighting period determined by the lighting period width information until the timing.

FIG. 9 also shows the total current I total supplied by the DC / DC converter 72 for each unit period.

According to FIG. 9, the DC / DC converter 72 supplies current in the 2nd to 4th unit period, the 6th to 8th unit period, and the 10th to 12th unit period. In addition, there is a peak of the total amount I 供給する total of current supplied by the DC / DC converter 72 in the fourth unit period, the eighth unit period, and the twelfth unit period.

Although the configuration of the backlight light source 711L has been described above, the backlight light sources 712L to 714L and 711R to 714R have the same configuration as the backlight light source 711L.

Here, when the LEDs A1, A2, A3, LEDs B1, B2, B3, and LEDs C1, C2, C3 are turned on according to the timing chart shown in FIG. 9, the following problems occur in the DC / DC converter 72. To do.

It is a problem that the DC / DC converter 72 and its surroundings may become hot enough that the heat generation of the DC / DC converter 72 increases and exceeds the temperature standard in the liquid crystal display device.

That is, the DC / DC converter 72 includes a switching element, and voltage is stepped down by switching of the switching element. However, when the LEDs A1, A2, A3, LEDs B1, B2, B3, and LEDs C1, C2, C3 are turned on according to the timing chart shown in FIG. 9, the period for supplying current to these LEDs is long. It reaches. Along with this, the period during which the switching element performs switching also extends for a long time. The power consumption of the DC / DC converter 72 increases as the period during which the switching element performs switching increases. In addition, when a period during which the switching element performs switching in one frame extends for a long time, conversion loss due to the switching increases. As a result, there is a concern that the heat generation of the DC / DC converter 72 is increased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a backlight light source, a backlight device, a DC / DC converter, and a peripheral device that can reduce the risk of the surrounding temperature becoming high. An object of the present invention is to provide a liquid crystal display device and a lighting control method for a backlight light source.

In order to solve the above problems, the backlight light source of the present invention is a backlight light source that illuminates a display area provided in a liquid crystal panel, and is lit by a current supplied from a DC / DC converter to display the display. A plurality of light emitting elements arranged so as to illuminate the area and form a matrix of three rows or more and two columns or more, and lighting and extinguishing are controlled for each of the plurality of light emitting elements, and image rewriting in the display area is performed. A lighting control unit that illuminates the light emitting element that illuminates a place where the response has been completed, and the lighting control unit performs lighting and lighting of all the light emitting elements included in the row for each row constituting the matrix. The first mode in which the reference position, which is at least one of the turn-off timings, differs from the reference position in at least two rows in the matrix, and the row Is characterized in that in all the rows can be switched between the second mode of not the reference position matches the.

Further, in order to solve the above-described problem, the backlight light source lighting control method of the present invention is a backlight light source lighting control method for illuminating a display area provided in a liquid crystal panel, and the backlight light source includes: The display area is illuminated by lighting with a current supplied from a DC / DC converter, and includes a plurality of light emitting elements arranged to form a matrix of 3 rows or more and 2 columns or more. Controls turning on and off for each light emitting element, turns on the light emitting element that illuminates the place where the image rewriting response is completed in the display area, and for each row constituting the matrix, all the light emission included in the row A first mode in which the reference position at which the element is turned on and off is different, and the reference position in at least two rows in the matrix; There match, and is characterized by switching a second mode in which the reference position in all the rows in the matrix do not match.

According to the above configuration, in the second mode, the reference positions are the same in at least two rows in the matrix of the plurality of light emitting elements. For this reason, in the second mode, the period during which the switching element of the DC / DC converter performs switching is shorter than that in the first mode. When the period during which the switching element performs switching is short, the power consumption of the DC / DC converter is reduced, and thus the heat generation of the DC / DC converter is reduced. Further, since the current from the DC / DC converter flows in a short period of time when the switching element performs switching, the conversion loss due to the switching is reduced, and the heat generation of the DC / DC converter is reduced.

As a result, it is possible to solve the problem that the DC / DC converter and its surroundings may become hot enough that the heat generation of the DC / DC converter increases and exceeds the temperature standard in the liquid crystal display device.

As described above, the backlight light source of the present invention is a backlight light source that illuminates a display area provided in a liquid crystal panel, and illuminates the display area by lighting with a current supplied from a DC / DC converter. A plurality of light emitting elements arranged so as to form a matrix having at least two rows and two or more columns, and a place where the response of image rewriting in the display area is completed by controlling turning on and off for each of the plurality of light emitting elements. A lighting control unit that turns on the light emitting element that illuminates the light source, and the lighting control unit is configured to turn on and off all the light emitting elements included in a row for each row constituting the matrix. The first mode having a different reference position, and the reference position coincides in at least two rows in the matrix, and all in the matrix It can be switched between the second mode of not the reference position matches in the row.

Further, the lighting control method of the backlight light source of the present invention is a lighting control method of the backlight light source that illuminates the display area provided in the liquid crystal panel, and the backlight light source is a current supplied from a DC / DC converter. The display area is illuminated by illuminating with a plurality of light emitting elements arranged to form a matrix of 3 rows or more and 2 columns or more, and lighting and extinguishing are controlled for each of the plurality of light emitting elements Then, the light emitting element that illuminates a place where the image rewriting response is completed in the display area is turned on, and at least one of lighting and extinguishing of all the light emitting elements included in the row for each row constituting the matrix The first mode having a different reference position, and the reference position coincides in at least two rows in the matrix, and the matrix In all rows kick switch and a second mode in which the reference position does not coincide.

Therefore, the present invention has an effect that it is possible to reduce the possibility that the DC / DC converter and its surroundings become hot.

It is a circuit diagram which shows schematic structure of the backlight light source which concerns on embodiment of this invention. It is a block diagram which shows the structure of the LED drive circuit of the backlight light source shown in FIG. It is a timing chart which shows an example of the timing which lights each LED in DC / DC heat_generation | fever reduction mode. It is a timing chart which shows an example of the timing which lights each LED in animation blur reduction mode. It is a table | surface which shows an example of the relationship between each mode which concerns on this invention, and the division | segmentation number defined by vertical direction division | segmentation information. It is a figure which shows the structural example of the principal part of the backlight apparatus and backlight light source which were conventionally provided in the local dimming liquid crystal display device. It is a block diagram which shows the structural example of the LED drive circuit of the backlight light source shown in FIG. It is a table | surface which shows the relationship between LED which turns on the backlight light source shown to FIG. 1 and FIG. 6, and the lighting period. FIG. 9 is a timing chart when the LED of the backlight source shown in FIG. 6 is turned on (normal mode) according to the table shown in FIG. 8.

FIG. 1 is a circuit diagram showing a schematic configuration of a backlight light source according to the present embodiment.

The backlight light source 11 shown in FIG. 1 is provided corresponding to one of a plurality of display areas obtained by dividing one display screen in a liquid crystal panel of a local dimming liquid crystal display device (not shown).

The backlight light source 11 shown in FIG. 1 has LEDs (light emitting elements) A1, A2, A3,..., LEDs B1, B2, B3,..., LEDs C1, C2, C3,. It has. For convenience of illustration, FIG. 1 shows only a total of nine LEDs (3 by 3 x 3), and the other LEDs are not shown. However, in practice, it is general that four or more LEDs are provided horizontally, and four or more LEDs may be provided vertically.

The backlight light source 11 further includes a DC / DC converter 12, an LED drive circuit 13, a plurality of switches 14, a plurality of resistors 15, and a power source 20.

Further, the DC / DC converter 12 includes a switching element 16, an inductor 17, a diode 18, and a capacitor 19.

LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,... Illuminate the display area corresponding to the backlight source 11.

LEDA1, A2, A3, ..., LEDB1, B2, B3, ... and LEDC1, C2, C3, ... have anodes connected to the DC / DC converter 12. Further, LEDs A1, A2, A3,..., LEDs B1, B2, B3,..., And LEDs C1, C2, C3,.

Further, LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,... Have a matrix similar to the backlight light source 711L shown in FIG. It is an arrangement to configure. That is, the LEDs A1, A2, A3,... Are arranged in a row horizontally. The same applies to LEDs B1, B2, B3,... And LEDs C1, C2, C3,. Moreover, LEDA1, B1, and C1 are arranged vertically, LEDA2, B2, and C2 are arranged vertically, and LEDA3, B3, and C3 are arranged vertically. The same applies to other LEDs not shown.

Incidentally, the backlight source 11 needs to have an LED arrangement that constitutes a matrix of 3 rows or more and 2 columns or more.

In addition, as a light emitting element, a well-known general light source can be utilized besides LED.

The DC / DC converter 12 steps down the voltage applied from the power source 20, and converts the current obtained from the stepped down voltage into LEDA1, A2, A3,..., LEDB1, B2, B3,. , C2, C3,... .., LEDB1, B2, B3,..., And LEDs C1, C2, C3,... Are turned on by the current supplied from the DC / DC converter 12.

The DC / DC converter 12 performs voltage step-down by switching of the switching element 16. Specifically, the DC / DC converter 12 generates a square wave voltage by switching of the switching element 16, leveles the output current by the inductor 17, and smoothes the output voltage by the capacitor 19. The diode 18 is a free-wheeling diode that establishes a current path when the switching element 16 is non-conductive. For example, the DC / DC converter 12 steps down a 40V DC voltage applied from the power supply 20 to generate a 20V DC voltage. Then, the DC / DC converter 12 converts the current flowing by the DC voltage of 20V to LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,. To supply.

The LED drive circuit 13 controls whether or not the LEDs A1, A2, A3,..., The LEDs B1, B2, B3,... And the LEDs C1, C2, C3,. A lighting timing determination unit (lighting control unit) 21 is provided. The LED driving circuit 13 drives these LEDs by the lighting timing determination unit 21 and controls lighting by the backlight light source 11.

Each of the switch 14 and the resistor 15 is provided in the same number as the total number of LEDs A1, A2, A3,..., LEDB1, B2, B3,..., And LEDs C1, C2, C3,. These LEDs are provided in one-to-one correspondence.

Here, LEDs A1, A2, A3,..., LEDB1, B2, B3,..., And LEDs C1, C2, C3,. And a resistor 15 is connected. That is, paying attention to any one of LEDA1, A2, A3,..., LEDB1, B2, B3,..., And LEDC1, C2, C3,. It is.

One end of the switch 14 is connected to the cathode of any one of the above LEDs. The other end of the switch 14 is connected to one end of the resistor 15. The other end of the resistor 15 is grounded. The LED, the switch 14 and the resistor 15 are connected in series with each other. Further, the series circuit of the LED, the switch 14 and the resistor 15 constitutes a series circuit with the DC / DC converter 12 and the power source 20.

By the way, when the switch 14 is closed, the LEDs connected in series with the switch 14 (LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,. Current) flows, and the LED lights up. On the other hand, when the switch 14 is opened, no current flows through the LED, and the LED is turned off.

The lighting timing determination unit 21 of the LED drive circuit 13 is configured to be able to open and close the plurality of switches 14 individually (in units of one switch 14). The lighting timing determination unit 21 opens and closes the plurality of switches 14 individually, thereby LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,. Can be individually controlled (for each light emitting element).

It should be noted that the lighting timing in this specification includes lighting end timing (that is, extinguishing timing) regardless of lighting start timing.

FIG. 2 is a block diagram showing the configuration of the LED drive circuit 13 of the backlight source 11.

As shown in FIG. 2, the LED drive circuit 13 receives lighting reference position information, lighting period width information, vertical division information, and peak current information in the lighting timing determination unit 21. The lighting timing determination unit 21 refers to the input information, and LEDA1, A2, A3,..., LEDB1, B2, B3,..., LEDC1, C2, C3,. Controls the timing of lighting.

The lighting reference position information (reference position information) is information that is also input to the lighting timing determination unit 81 shown in FIG. 7, and determines the lighting timing and the reference for the timing for lighting each of the LEDs to be lit ( Reference position). In other words, the lighting reference position information indicates the reference in each of the LEDs A1, A2, A3,..., The LEDs B1, B2, B3,... And the LEDs C1, C2, C3,. Information.

The lighting period width information is information that is also input to the lighting timing determination unit 81 illustrated in FIG. 7 and is information that indicates a period (width) during which each of the LEDs that are the target of lighting timing and lighting is lit. . In other words, the lighting period width information indicates a period during which each of the LEDs A1, A2, A3,..., The LEDs B1, B2, B3,... And the LEDs C1, C2, C3,. Information.

Since the lighting reference position information and the lighting period width information are described in detail in the description part with reference to FIG. 7, detailed description thereof is omitted here.

The vertical direction division information is a standard defined by the lighting reference position information for LEDs A1, A2, A3,..., LEDB1, B2, B3,..., And LEDs C1, C2, C3,. It is the information which shows the line which makes the timing common. In other words, the vertical division information is information indicating a line that matches the criteria individually defined for each of the A-line to the C-line (that is, which line and which line are matched). It is.

As an example, let us consider a case where the vertical direction division information is information indicating that the reference is matched between the A row and the B row. In this case, the lighting timing determination unit 21 that has received the vertical division information includes the LEDs A1, A2, A3,... Constituting the A row and the LEDs B1, B2, B3,. , Standardize the reference timing.

The peak current information is the current (DC) supplied from the DC / DC converter 12 to the LEDs A1, A2, A3,..., The LEDs B1, B2, B3,. This is information indicating the upper limit value of the total amount of current I total).

The lighting reference position information, lighting period width information, vertical direction division information, and peak current information are all input to the lighting timing determination unit 21 from the outside of the backlight source 11. However, the lighting reference position information, the lighting period width information, the vertical direction division information, and the peak current information may all be input from the inside of the backlight light source 11 to the lighting timing determination unit 21.

From here, in this embodiment, specific examples of timings for lighting the LEDs A1, A2, and A3, the LEDs B1, B2, and B3, and the LEDs C1, C2, and C3 by the lighting timing determination unit 21 by mode are described. explain.

In the following, it is assumed that the relationship between the LED to be turned on and the lighting period is as shown in the table of FIG. That is, in this embodiment, each of the LEDs A1, A2, A3, the LEDs B1, B2, B3, and the LEDs C1, C2, C3 is lit in the same lighting period as that in the timing chart shown in FIG. To do.

In addition, in this embodiment, the LEDs A1, A2, A3, LEDs B1, B2, B3, and LEDs C1, C2, C3 are turned on mainly at different timings from the lighting in the timing chart shown in FIG. An example to be performed will be described.

First, the normal mode (first mode) will be described. This normal mode means lighting according to the timing chart shown in FIG.

As described with reference to FIG. 9 with reference to the lighting reference position information and the lighting period width information, the lighting timing determination unit 21 performs LEDA1, A2, A3, LEDB1, B2, B3, and LEDC1 in the normal mode. , C2, and C3 can be controlled.

Subsequently, the DC / DC heat generation reduction mode (second mode) will be described. The DC / DC heat generation reduction mode is a mode for the purpose of reducing the heat generation of the DC / DC converter 12.

FIG. 3 is a timing chart showing an example of timing for lighting each LED in the DC / DC heat generation reduction mode. FIG. 3 shows the timing and the waveform of I total in the same manner as in FIG.

The timing chart shown in FIG. 3 is an example in the case where the vertical division information is information indicating that the reference is matched between the A row and the B row. In this case, the lighting timing determination unit 21 that has received the vertical division information includes the LEDs A1, A2, A3,... Constituting the A row and the LEDs B1, B2, B3,. , Standardize the reference timing.

LEDB1, B2, and B3 are based on the lighting reference position information, and the end point of the eighth unit period is the lighting end timing, as in the timing chart shown in FIG. Each of the LEDs B1, B2, and B3 is lit for the lighting period determined by the lighting period width information until the timing.

On the other hand, according to only the lighting reference position information, LEDs A1, A2, and A3 have the lighting end timing at the end of the fourth unit period, as in the timing chart shown in FIG.

However, the standards of LEDs A1, A2, and A3 are shared with those of LEDs B1, B2, and B3 by the vertical division information. As a result, the end time of the eighth unit period of the LEDs A1, A2, and A3 is set as the lighting end timing (see the lighting reference positions of the A and B rows in FIG. 3). Each of the LEDs A1, A2, and A3 is lit for the lighting period determined by the lighting period width information until the timing.

The switching frequency of the switching element 16 is about 150 kHz, which is very high speed. For this reason, in the switching by the switching element 16, power consumption is increased, which is a cause of heat generation in the DC / DC converter 12.

However, in the DC / DC heat generation reduction mode, it is not necessary to turn on the LED in the first to fourth unit periods as shown in the timing chart of FIG. Therefore, the first to fourth unit periods do not correspond to the period in which the switching element 16 of the DC / DC converter 12 performs switching. That is, the period during which the switching element 16 performs switching is shorter than the normal mode shown in FIG.

As described above, in the DC / DC heat generation reduction mode, in the A row and the B row, the timing standards for turning on the respective LEDs constituting these rows are the same. For this reason, in the DC / DC heat generation reduction mode, the period during which the switching element 16 of the DC / DC converter 12 performs switching is shorter than that in the normal mode. When the period during which the switching element 16 performs switching is short, the power consumption of the DC / DC converter 12 is reduced, and thus the heat generation of the DC / DC converter 12 is reduced. Further, since the current from the DC / DC converter 12 flows in a short period of time when the switching element 16 performs switching, conversion loss due to the switching is reduced, and heat generation of the DC / DC converter 12 is reduced.

As a result, it is possible to solve the problem that the DC / DC converter 12 and its surroundings may become hot enough that the heat generation of the DC / DC converter 12 increases and exceeds the temperature standard in the liquid crystal display device. Become.

In addition, the lighting timing determination unit 21 matches the reference in the A row and the reference in the B row with the reference in the B row, which is the latest timing in the normal mode, in the DC / DC heat generation reduction mode. ing.

In order to reduce the blurring of the moving image displayed in the display area, it is necessary to turn on the LED in order from the one that illuminates the place where the image rewriting response is completed in the display area. However, in realizing the DC / DC heat generation reduction mode, when the standard is made common by advancing the reference timing from the normal mode, an LED that illuminates a location where the image rewriting response has not been completed is lit. There is a possibility that blurring of the moving image occurs at the location.

According to the timing chart shown in FIG. 3, the DC / DC heat generation reduction mode is realized by delaying the reference timing in the A row to the reference timing in the B row with respect to the normal mode. I don't go early. In this way, by realizing the DC / DC heat generation reduction mode only by delaying the reference timing from the normal mode, there is no possibility that the LED that illuminates the portion where the response of the image rewriting has not been completed, It is possible to reliably reduce the blurring of the moving image displayed in the display area.

Further, it is preferable that the lighting timing determination unit 21 switches to the DC / DC heat generation reduction mode when the temperature of the DC / DC converter 12 exceeds a predetermined temperature.

According to the above configuration, when the temperature of the DC / DC converter 12 becomes high, the mode is switched to the DC / DC heat generation reduction mode so that the heat generation of the DC / DC converter 12 is reduced. Therefore, it can suppress that the DC / DC converter 12 becomes high temperature.

Here, the predetermined temperature may be, for example, a temperature determined by a temperature standard in a liquid crystal display device including the backlight source 11 or a temperature uniquely determined by the manufacturer or user of the backlight source 11. It may be.

The DC / DC heat generation reduction mode is a mode in which the lighting timing criteria are made to coincide with each other for a plurality of rows in a matrix of a plurality of LEDs for which the DC / DC converter 12 is in charge of lighting.

Specifically, in the DC / DC heat generation reduction mode, when the DC / DC converter 12 is at a high temperature, the number of divisions (the number of rows of the matrix having different references) is reduced according to the vertical direction division information. Moreover, if the DC / DC converter 12 becomes low temperature, the number of divisions may be increased. For example, if the DC / DC converter 12 becomes hot, the number of divisions is reduced and the lighting reference positions of the A and B rows are made common. At this time, the period during which the current flows is shortened, the period during which the switching element 16 of the DC / DC converter 12 performs switching is reduced, and the conversion efficiency is improved by causing a large amount of current to flow during the period. Thus, the heat generation of the DC / DC converter 12 can be suppressed.

However, as the number of lines for standardization increases, the effect of reducing moving image blur becomes smaller, so it is necessary to pay attention to this point. In particular, if the reference is matched in all rows (in the case of the backlight light source 11, all rows A to C), the backlight light source 11 is turned on all at once. Since such a lighting operation is considered to be a conventional lighting operation, it cannot be said to be appropriate as the present embodiment. In other words, in the DC / DC heat generation reduction mode, the reference should not be matched in all rows composed of a plurality of LEDs.

Subsequently, the motion blur reduction mode (third mode) will be described. This moving image blur reduction mode aims to reduce the peak value of the total amount of current I 供給する total supplied by the DC / DC converter 12 while maintaining the same level of motion blur reduction effect as the normal mode. It is a mode to do.

FIG. 4 is a timing chart showing an example of timing for lighting each LED in the moving image blur reduction mode. FIG. 4 shows the timing and the waveform of I total in the same manner as in FIGS.

Here, the value of the total current I 量 total when the L LEDs are lit for the M unit period is referred to as “current value: N”. However, L and M are both natural numbers, and N is a product of L and M. For example, the value of the total current I total when three LEDs are lit for two unit periods is expressed as current value: 6.

The timing chart shown in FIG. 4 is an example in the case where the peak current information is information indicating that the upper limit value of the total current I total is the current value: 2. In this case, the lighting timing determination unit 21 that has received the peak current information adjusts the reference timing for each LED so that the number of LEDs that are simultaneously turned on is two or less.

For LEDs A1, A2, and A3, according to only the lighting reference position information, the end point of the fourth unit period is set as the lighting end timing, as in the timing chart shown in FIG. However, in this case, in the fourth unit period, the total amount of current I total is a current value: 3, which exceeds the upper limit value indicated by the peak current information.

Therefore, in the moving image blur reduction mode, for example, as shown in the timing chart of FIG. 4, the lighting end timings of the LEDs A1 and A2 are maintained (refer to the lighting reference positions of the LEDs A1 and A2 in FIG. 4). On the other hand, the end point of the second unit period of the LEDA3 is the lighting end timing (see the lighting reference position of the LEDA3 in FIG. 4). Each of the LEDs A1, A2, and A3 is lit for the lighting period determined by the lighting period width information until the timing.

The same applies to LEDs B1, B2, and B3 and LEDs C1, C2, and C3.

That is, the lighting end timings of the LEDs B2 and B3 are maintained at the end point of the eighth unit period (see the lighting reference positions of the LEDs B2 and B3 in FIG. 4). On the other hand, the end time of the seventh unit period of LEDB1 is the lighting end timing (see the lighting reference position of LEDB1 in FIG. 4). Each of the LEDs B1, B2, and B3 is lit for the lighting period determined by the lighting period width information until the timing.

Further, the lighting end timings of the LEDs C2 and C3 are maintained at the end point of the 12th unit period (see the lighting reference positions of the LEDs C2 and C3 in FIG. 4). On the other hand, the end point of the 10th unit period of LEDC1 is the lighting end timing (see the lighting reference position of LEDC1 in FIG. 4). Each of the LEDs C1, C2, and C3 is lit for the lighting period determined by the lighting period width information until the timing.

As a result, in the 1st to 12th unit period, the peak value of the total amount of current I total is the current value: 2. In the normal mode, the peak value is the current value: 3 according to the timing chart shown in FIG. 9, and in the DC / DC heat generation reduction mode, the peak value is the current value: according to the timing chart shown in FIG. 6. Therefore, in the moving image blur reduction mode, the peak value in the 1st to 12th unit periods can be reduced.

In the moving image blur reduction mode, the operation is performed so as to reduce the number of the plurality of LEDs that are simultaneously lit, so that the peak value of the total amount of current I 供給する total that the DC / DC converter 12 supplies to the plurality of LEDs can be reduced. Become.

As a result, the peak value of the total amount of current I 供給する total supplied by the DC / DC converter 12 becomes large, and the problem that the rating of the current flowing through the DC / DC converter 12 may be exceeded can be solved. .

Further, according to the timing chart shown in FIG. 4, for row A, LEDA3 is lit while LEDA2 is lit. For row B, LEDB1 is lit while LEDB3 is lit, and for row C, LEDC1 is lit while LEDC3 is lit.

That is, in the moving image blur reduction mode, the lighting timing determination unit 21 lights up the LEDs that are targets of different standards while the other LEDs configuring the same row are on.

Thereby, it is possible to reduce the peak value of the total amount I 供給する total of the current that the DC / DC converter 12 supplies to the plurality of LEDs without increasing the period during which the switching element 16 of the DC / DC converter 12 performs switching. Become. Moreover, according to this, it is not necessary to change significantly the lighting timing of LED used as the object from which a reference | standard differs. Therefore, the possibility that the timing at which the response of rewriting the image is completed and the lighting timing of the LED are remarkably shifted is reduced.

Further, it is preferable that the lighting timing determination unit 21 switches to the moving image blur reduction mode when the total amount I total of the current supplied from the DC / DC converter 12 to the plurality of LEDs exceeds a predetermined current value.

Thus, when the total amount of current I total becomes large, the mode is switched to the motion blur reduction mode, and the peak value of the total amount of current I total is reduced. Therefore, it can suppress that this peak value becomes large.

Here, the predetermined current value may be, for example, a current value less than or equal to the rated current flowing in the DC / DC converter 12, or a current value uniquely determined by the manufacturer or user of the backlight light source 11. May be.

The moving image blur reduction mode is a mode in which the lighting timing is changed so that the lighting does not overlap in the period after the response period of the liquid crystal panel.

Specifically, this is a mode in which the lighting timing of each LED is determined based on the peak current information so as not to exceed the upper limit value indicated by the peak current information.

Note that it is possible to combine the DC / DC heat generation reduction mode and the moving image reduction mode. That is, the upper limit value is determined for the total current I total supplied by the DC / DC converter 12 shown in the timing chart of FIG. Then, in order to prevent the total amount I total of the current from exceeding the upper limit value, the lighting timing determination unit 21 determines the number of LEDs that are simultaneously turned on with respect to the DC / DC heat generation reduction mode with respect to the timing chart shown in FIG. Therefore, the reference timing is adjusted for each LED so as to reduce the power consumption. Thereby, it is possible to easily combine the DC / DC heat generation reduction mode and the moving image blur reduction mode.

In addition, in this Embodiment, although the lighting timing determination part 21 to which both vertical direction division | segmentation information and peak current information are input is illustrated, the structure of the lighting timing determination part 21 is not limited to this.

That is, when only the normal mode and the DC / DC heat generation reduction mode are performed (that is, only the heat generation of the DC / DC converter 12 is concerned), the lighting direction determination unit 21 receives the vertical direction division information. The peak current information may not be input. On the other hand, when only the normal mode and the moving image blur reduction mode are performed (that is, only the peak value of the total amount I total of the current that the DC / DC converter 12 supplies to the plurality of LEDs is concerned), the lighting timing determination unit 21 While the peak current information is input, the vertical division information may not be input.

Further, the vertical division information is not limited to being input to the lighting timing determination unit 21 based on the temperature of the DC / DC converter 12. For example, even if the vertical division information is not input, the lighting timing determination unit 21 predicts the temperature of the DC / DC converter 12 based on the lighting timing at which each LED is actually lit in the past. It is also possible to generate vertical division information.

Further, it is preferable that the lighting timing determination unit 21 switches each mode in accordance with an instruction from the outside of the backlight light source 11.

Thereby, for example, it is possible to switch between the normal mode, the DC / DC heat generation reduction mode, and the moving image blur reduction mode in accordance with an instruction from the user.

In addition, a table showing various patterns of lighting reference position information, lighting period width information, and vertical direction division information in the DC / DC heat generation reduction mode is prepared in advance, and the lighting timing determination unit 21 refers to the table. DC / DC heat generation reduction mode can be implemented. In addition, a table indicating various patterns of lighting reference position information, lighting period width information, and peak current information in the moving image blur reduction mode is prepared in advance, and the lighting timing determination unit 21 refers to the table to move the moving image blur. A reduction mode can be implemented.

Further, the temperature of the DC / DC converter 12 is measured by a temperature sensor (not shown) provided outside the backlight light source 11, and when the temperature exceeds a predetermined threshold, the mode is switched to the DC / DC heat generation reduction mode. It is possible to perform advanced switching such as. Further, when the value of the current I total output from the DC / DC converter 12 is measured by a current measuring device (not shown) provided outside the backlight light source 11 and this value exceeds a predetermined threshold value, It is possible to perform advanced switching such as switching to the motion blur reduction mode.

Incidentally, the vertical division information is generally controlled by a microcomputer based on the menu of the liquid crystal display device, and the peak current information is generally determined according to the standard in the liquid crystal display device. That is, the vertical direction division information and the peak current information are determined in the liquid crystal display device.

Also, a switch 14 connected in series with each LED is provided, and the lighting timing determination unit 21 controls the lighting timing of each LED according to each mode by opening and closing each switch 14. As a result, the control can be easily performed.

In the present embodiment, an example in which the switch 14 is provided outside the LED drive circuit 13 has been described. However, the switch 14 may be provided inside the LED drive circuit 13.

Further, it is preferable that the timing for terminating the lighting of the LED substantially coincides with the timing for starting rewriting of the image in the display area illuminated by the LED.

As described above, the backlight source 11 illuminates the display area provided on the liquid crystal panel. The backlight light source 11 illuminates the display area by being lit by the current supplied from the DC / DC converter 12, and as a plurality of light emitting elements arranged to form a matrix of 3 rows or more and 2 columns or more, LEDA1, A2, A3,..., LEDB1, B2, B3,..., And LEDs C1, C2, C3,. The backlight light source 11 includes a lighting timing determination unit 21 that controls lighting and extinguishing for each of these LEDs, and lights the LEDs that illuminate a portion where the image rewriting response has been completed in the display area. Then, the lighting timing determination unit 21 performs the normal mode in which the reference position that is the timing of at least one of lighting and extinguishing of all the LEDs included in the row is different for each row of the LEDs, and the reference position in at least two rows. Can be switched to the DC / DC heat generation reduction mode in which the reference positions do not match in all rows.

Further, the lighting control method of the backlight light source 11 can be interpreted as follows.

This is a lighting control method for a backlight light source 11 that illuminates a display area provided on a liquid crystal panel. The backlight light source 11 illuminates the display area by lighting with a current supplied from a DC / DC converter 12, and has three rows. A plurality of LEDs arranged so as to form a matrix of two or more columns is provided, and lighting and extinguishing are controlled for each of the plurality of LEDs to illuminate a place where an image rewriting response is completed in the display area. The LED is turned on, and for each LED row, the normal mode in which the reference position at which at least one of the lighting and extinguishing timings of all the LEDs included in the row is different matches the reference position in at least two rows, In addition, the DC / DC heat generation reduction mode in which the reference positions do not match in all rows is switched.

Further, the backlight device according to the present embodiment includes a plurality of backlight light sources 11 provided for each of a plurality of display areas obtained by dividing one display screen in a liquid crystal panel. As a specific example, in the backlight device 70 shown in FIG. 6, each of the backlight light sources 711L to 714L and 711R to 714R is constituted by the backlight light source 11.

Further, the liquid crystal display device according to the present embodiment includes the backlight device according to the present embodiment. A specific example of the liquid crystal display device is a local demming liquid crystal display device.

According to the above configuration, a backlight device and a liquid crystal display device that achieve the same effect as the backlight light source 11 can be realized.

Here, in one of the liquid crystal display devices, the vertical division information and the peak current information can be set depending on the operation mode or the like.

Specifically, the DC / DC heat generation reduction mode (advanced mode (strong / standard), standard mode, etc.) is a mode in which reduction of heat generation of the DC / DC converter 12 is emphasized. In this mode, heat generation of the DC / DC converter 12 is suppressed by setting a short period for switching the switching element 16 of the DC / DC converter 12.

The moving image blur reduction mode (scan mode) is a mode in which importance is attached to reducing the blur of moving images.

In this mode, it is required to turn on the LED that illuminates the display area almost simultaneously with the response to the rewriting of the image in the display area. Here, the rewriting is performed by the number of rows (lines) equal to or more than the number of rows of the plurality of LEDs that are arranged in a matrix. For example, in FHD (Full High Definition), about 10 rows of LEDs are arranged while the rewriting is 1080 lines. For this reason, it is desired to increase the number of divisions (number of rows of the matrix having different references) determined by the vertical direction division information. Further, if the lighting of the LED is limited only after the response of the rewriting, the lighting period of the LED is shortened. For this reason, it is desirable to increase the current flowing through one LED as much as possible so that the screen does not become dark.

Furthermore, as a mode in which both the reduction of heat generation of the DC / DC converter 12 and the reduction of blurring of moving images are emphasized, a mode called a DC / DC heat generation reduction / moving image blur reduction mode can be considered.

The DC / DC heat generation reduction / moving image blur reduction mode is the same as the DC / DC heat generation reduction mode in that importance is placed on the reduction of heat generation of the DC / DC converter 12, but the motion image blur is reduced as much as possible. It is a mode to make it. In the DC / DC heat generation reduction / moving image blur reduction mode, the total amount of current I 発熱 total supplied by the DC / DC converter 12 in the DC / DC heat generation reduction mode is set to the upper limit value or less as shown in the timing chart of FIG. That is, the DC / DC heat generation reduction / moving image blur reduction mode referred to here is a mode in which the DC / DC heat generation reduction mode and the moving image blur reduction mode are combined.

In the DC / DC heat generation reduction / moving image blur reduction mode, it is preferable to increase the number of divisions of the portion where the displayed image has a motion by the vertical division information. On the other hand, when the temperature of the DC / DC converter 12 is measured and the temperature approaches the rating, the temperature increase of the DC / DC is reduced by reducing the number of divisions beforehand using the vertical direction division information. It is possible. However, in that case, the effect of reducing the blur of the moving image is reduced.

In this case, it is conceivable to set the following parameters from a microcomputer or the like (see FIG. 5). FIG. 5 is a table showing an example of the relationship between each mode described above and the number of divisions determined by the vertical direction division information.

The peak current information preferably indicates a current value that satisfies a rating (hereinafter referred to as “Imax”) relating to the current flowing through the DC / DC converter 12.

Here, in the moving image blur reduction mode, it is required to increase the current (hereinafter referred to as “Ich”) per LED, but conventionally, when there are N LEDs having the same lighting reference position information, It was necessary to set Ich so as to satisfy the following formula (1).

Imax> N × Ich (1)
However, depending on the period during which the LED is lit, it may be necessary to set the Ich by further considering LEDs with different lighting reference position information.

On the other hand, in the backlight source 11, even if Ich is set to a value that does not satisfy the above formula (1), it can be adjusted to satisfy Imax.

Besides, when the temperature around the liquid crystal display device is high, the DC / DC converter 12 is likely to become high temperature, so it is conceivable to increase the number of divisions determined by the vertical division information.

By the way, when the LEDs A1, A2, A3, LEDs B1, B2, B3, and LEDs C1, C2, C3 are turned on according to the timing chart shown in FIG. 9, the following problems occur in the DC / DC converter 72. It is also possible.

It is a problem that the peak value of the total amount of current I 供給する total supplied by the DC / DC converter 72 becomes large and may exceed the rating of the current flowing through the DC / DC converter 72.

In order to solve the above problem, the lighting control unit of the backlight source of the present invention reduces the number of the first mode, the second mode, and the plurality of light emitting elements that are simultaneously lit. In addition, it is preferable that switching to the third mode in which the reference position is adjusted for each light emitting element is possible.

According to the above configuration, in the third mode, since the operation is performed so as to reduce the number of the plurality of light emitting elements that are simultaneously turned on, the peak value of the total amount of current that the DC / DC converter supplies to the plurality of light emitting elements is reduced. It becomes possible to do.

As a result, it is possible to solve the problem that the peak value of the total amount of current supplied by the DC / DC converter is increased, and there is a possibility that the rating of the current flowing through the DC / DC converter may be exceeded.

In the second mode, the lighting control unit of the backlight light source according to the present invention sets the reference positions of all the light emitting elements included in a row for each row constituting the matrix in the first mode. It is preferable to match the reference position that is the slowest in the above.

In order to reduce blurring of the moving image displayed in the display area, it is necessary to turn on the light emitting elements in order from the one that illuminates the place where the image rewriting response is completed in the display area. However, when the second mode is realized, if the timing of the reference position is advanced from the first mode, a light emitting element that illuminates a place where the response of rewriting the image is not completed, and the moving image is There is a risk of blurring.

According to the above configuration, the second mode is realized only by delaying the timing of the reference position from the first mode. Therefore, there is no possibility that the light emitting element that illuminates the portion where the response of rewriting the image is not completed, and it is possible to reliably reduce the blur of the moving image displayed in the display area.

In the backlight light source of the present invention, the lighting control unit includes reference position information indicating the reference position in each of the plurality of light emitting elements, and a lighting period width indicating a period in which each of the plurality of light emitting elements is turned on. It is preferable to implement the second mode with reference to information and vertical division information indicating rows in the matrix that match the reference position.

Further, it is preferable that the lighting control unit of the backlight source of the present invention switches to the second mode when the temperature of the DC / DC converter exceeds a predetermined value.

According to the above configuration, when the temperature of the DC / DC converter becomes high, the mode is switched to the second mode and operates to reduce the heat generation of the DC / DC converter. Therefore, it can suppress that a DC / DC converter becomes high temperature.

Further, the lighting control unit of the backlight source of the present invention may be configured such that, in the third mode, the light emitting elements to be subjected to the different reference positions are the same as the other light emitting elements constituting the same row in the matrix. It is preferable to light up during lighting.

According to said structure, it becomes possible to make small the peak value of the electric current which this DC / DC converter supplies to several light emitting elements, without lengthening the period for which the switching element of a DC / DC converter switches. . Moreover, according to said structure, it is not necessary to change significantly the timing of lighting of the light emitting element used as the object from which the said reference position differs.

In the backlight light source of the present invention, the lighting control unit includes reference position information indicating the reference position in each of the plurality of light emitting elements, and a lighting period width indicating a period in which each of the plurality of light emitting elements is turned on. It is preferable to implement the third mode with reference to the information and peak current information indicating the upper limit value of the current supplied to the plurality of light emitting elements by the DC / DC converter.

Moreover, it is preferable that the lighting control unit of the backlight source of the present invention switches to the third mode when a current supplied to the plurality of light emitting elements by the DC / DC converter exceeds a predetermined value. .

According to the above configuration, when the current supplied from the DC / DC converter to the plurality of light emitting elements becomes large, the mode is switched to the third mode so that the peak value of the current is reduced. Accordingly, it is possible to suppress an increase in the peak value of the current supplied from the DC / DC converter to the plurality of light emitting elements.

In addition, it is preferable that the lighting control unit of the backlight light source of the present invention switches the above mode according to an instruction from the outside of the backlight light source.

According to the above configuration, for example, it is possible to switch between the first to third modes in accordance with an instruction from the user.

In addition, a table indicating various patterns of the reference position information, lighting period width information, and vertical direction division information in the second mode is prepared in advance, and the lighting control unit performs the second mode with reference to the table. can do. In addition, a table indicating various patterns of reference position information, lighting period width information, and peak current information in the third mode is prepared in advance, and the lighting control unit refers to the table and performs the third mode. be able to.

Further, according to the above configuration, the temperature of the DC / DC converter is measured by the temperature sensor provided outside the backlight light source, and when the temperature exceeds a predetermined threshold, the mode is switched to the second mode, etc. It is possible to perform such advanced switching. Further, according to the above configuration, when a current value output from the DC / DC converter is measured by a current measuring device provided outside the backlight light source, and the current value exceeds a predetermined threshold, It is possible to perform advanced switching such as switching to the 3 mode.

The backlight light source of the present invention includes a plurality of switches connected in series to each of the plurality of light emitting elements, and the lighting control unit opens and closes the plurality of switches individually, thereby It is preferable to individually control the timing of turning on and off the plurality of light emitting elements.

According to the above configuration, the lighting and extinguishing timing of each light emitting element according to each of the first to third modes can be easily realized by opening and closing the switch connected in series to each light emitting element. It becomes possible.

The backlight device of the present invention is a backlight device having a backlight light source for each of a plurality of display areas formed by dividing one display screen in a liquid crystal panel, and each of the backlight light sources is The backlight light source of the present invention is a feature.

The liquid crystal display device of the present invention includes the backlight device of the present invention.

According to the above configuration, it is possible to realize a backlight device and a liquid crystal display device that have the same effect as the backlight light source of the present invention.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

The present invention can be used for a backlight light source provided corresponding to one of a plurality of display areas obtained by dividing one display screen in a liquid crystal panel. The present invention also provides a backlight device including a plurality of backlight light sources provided corresponding to each of the plurality of display regions, a local demming liquid crystal display device including the backlight device, and the backlight. It can be used in a lighting light source control method.

11, 711L Backlight light source 12 DC / DC converter 14 Switch 16 Switching element 21 Lighting timing determination part (lighting control part)
70 Backlight devices A1, A2, A3, ... LED (light emitting element)
B1, B2, B3, ... LED (light emitting element)
C1, C2, C3, ... LED (light emitting element)
I total The total amount of current that the DC / DC converter supplies to multiple light-emitting elements

Claims

A backlight source that illuminates a display area provided on a liquid crystal panel,
A plurality of light emitting elements arranged so as to illuminate the display area by lighting with a current supplied from a DC / DC converter and constitute a matrix of 3 rows or more and 2 columns or more;
A lighting control unit for controlling lighting and extinguishing for each of the plurality of light emitting elements, and for lighting the light emitting elements that illuminate a place where an image rewriting response in the display area is completed,
The lighting control unit
A first mode in which a reference position that is a timing of at least one of lighting and extinguishing of all the light emitting elements included in a row is different for each row constituting the matrix;
A backlight light source characterized in that switching to a second mode in which the reference position is the same in at least two rows in the matrix and the reference position is not the same in all rows in the matrix is possible.
The lighting control unit switches between the first mode, the second mode, and a third mode in which the reference position is adjusted for each light emitting element so as to reduce the number of the plurality of light emitting elements that are simultaneously turned on. The backlight light source according to claim 1, wherein:
In the second mode, the lighting control unit
2. The backlight source according to claim 1, wherein, for each row constituting the matrix, the reference positions of all the light emitting elements included in the row are matched with the slowest reference position in the first mode. .
The lighting control unit
Reference position information indicating the reference position in each of the plurality of light emitting elements;
Lighting period width information indicating a period for lighting each of the plurality of light emitting elements;
2. The backlight source according to claim 1, wherein the second mode is implemented with reference to vertical division information indicating a row in the matrix that matches the reference position.
The lighting control unit
The backlight light source according to claim 1, wherein when the temperature of the DC / DC converter exceeds a predetermined value, the mode is switched to the second mode.
In the third mode, the lighting control unit
3. The backlight source according to claim 2, wherein the light emitting elements that are targets of different reference positions are turned on while the other light emitting elements constituting the same row in the matrix are turned on.
The lighting control unit
Reference position information indicating the reference position in each of the plurality of light emitting elements;
Lighting period width information indicating a period for lighting each of the plurality of light emitting elements;
3. The backlight source according to claim 2, wherein the third mode is implemented with reference to peak current information indicating an upper limit value of a current supplied to the plurality of light emitting elements by the DC / DC converter. .
The lighting control unit
The backlight light source according to claim 2, wherein when the current supplied to the plurality of light emitting elements by the DC / DC converter exceeds a predetermined value, the mode is switched to the third mode.
The backlight light source according to claim 1, wherein the lighting control unit switches the mode according to an instruction from the outside of the backlight light source.
A plurality of switches connected in series to each of the plurality of light emitting elements,
The backlight light source according to claim 1, wherein the lighting control unit individually controls lighting and extinguishing timings of the plurality of light emitting elements by individually opening and closing the plurality of switches.
A backlight device including a backlight light source for each of a plurality of display areas obtained by dividing one display screen in a liquid crystal panel,
The backlight device according to any one of claims 1 to 10, wherein each of the backlight light sources is the backlight light source according to any one of claims 1 to 10.
A liquid crystal display device comprising the backlight device according to claim 11.
A lighting control method for a backlight light source that illuminates a display area provided on a liquid crystal panel,
The backlight light source includes a plurality of light emitting elements arranged so as to illuminate the display area by being turned on by a current supplied from a DC / DC converter to form a matrix of three rows or more and two columns or more. And
Control lighting and extinction for each of the plurality of light emitting elements, to turn on the light emitting elements that illuminate the location where the response of image rewriting in the display area is completed,
A first mode in which a reference position that is a timing of at least one of lighting and extinguishing of all the light emitting elements included in a row is different for each row constituting the matrix;
A method for controlling lighting of a backlight source, wherein the second mode in which the reference position matches in at least two rows in the matrix and the reference position does not match in all rows in the matrix is switched.