KR20060070347A - Backlight apparatus and display device - Google Patents

Abstract

The present invention relates to a backlight device, the backlight device includes a light source unit having a light source, a cooling device for discharging heat generated from the light source unit to the outside, a temperature sensing unit for changing the state of the signal output according to the temperature of the light source unit, and A control unit configured to control an operation of the cooling device according to the on / off signal and the temperature detection signal, and an on / off signal whose state is determined according to the operation of the light source and the temperature detection signal are input. It includes. As a result, since the operation of the cooling device is controlled not only in the operating state of the light source unit but also in the ambient temperature, the cooling effect is increased and unnecessary power consumption is reduced. In addition, since unnecessary cooling devices are eliminated, noise is reduced and life is extended.

LCD, LCD, Backlight, LED, Cooling System, Cooling Fan, Temperature Sensor, Thermistor

Description

Backlight Device and Display Device {BACKLIGHT APPARATUS AND DISPLAY DEVICE}

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is an equivalent circuit diagram of one pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a block diagram of a cooling unit according to an embodiment of the present invention.

5 is a flowchart illustrating an operation of a controller according to an exemplary embodiment of the present invention.

The present invention relates to a backlight device and a display device.

Display devices used in monitors and TVs of computers include light emitting diodes (LEDs), electroluminescence (EL), vacuum fluorescent displays (VFDs), and electroluminescent devices (fields). emission display (FED), plasma display panel (PDP), and the like, a liquid crystal display (LCD) that does not emit light by itself and requires a light source.                         

A general liquid crystal display device includes two display panels provided with a field generating electrode and a liquid crystal layer having dielectric anisotropy interposed therebetween. A voltage is applied to the field generating electrode to generate an electric field in the liquid crystal layer, and the voltage is changed to adjust the intensity of the electric field, thereby adjusting the transmittance of light passing through the liquid crystal layer to obtain a desired image.

In this case, the light may be a separate artificial light source or natural light.

As a light source for a liquid crystal display, that is, a backlight device, a plurality of fluorescent lamps or light emitting diodes (LEDs), such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL), are used as a light source. Use

In the case of using a fluorescent lamp, the power consumption is large and the device characteristics of the liquid crystal display are deteriorated due to heat generation. In addition, since fluorescent lamps are typically rod-shaped, they are susceptible to shock and have a high risk of damage.

On the other hand, since the light emitting diode is a semiconductor device, it has a long life, a fast lighting speed, and low power consumption. In addition, it is strong in impact and advantageous in miniaturization and thinning.

Therefore, a light emitting diode is used as a light source of a backlight device not only for a small liquid crystal display device such as a mobile phone but also for a medium and large liquid crystal display device such as a monitor or a television.

 However, the operation of such a light source generates a lot of heat, and especially in the case of medium and large size, the amount of heat generated by increasing the size and number of light sources used increases. This heat adversely affects not only the light source but also the peripheral device. Therefore, the backlight device is generally attached to a cooling device such as a cooling fan near the portion where the light source is mounted.

Therefore, the technical problem to be achieved by the present invention is to improve the operating efficiency of the cooling device.

Another technical problem to be achieved by the present invention is to draw power consumption due to the operation of the cooling device.

According to an aspect of the present invention, a backlight unit includes a light source unit including a light source, a cooling device for discharging heat generated from the light source unit to the outside, and a temperature at which a state of a signal output is changed according to the temperature of the light source unit. A sensing unit and an on / off signal whose state is determined according to the operation of the light source and a temperature sensing signal from the temperature sensing unit are input, and the operation of the cooling apparatus according to the on / off signal and the temperature sensing signal It includes a control unit for controlling.

According to another aspect of the present invention, a display device includes a plurality of pixels arranged in a matrix, a light source unit including at least one light source for supplying light to the pixels, and a cooling device to discharge heat generated from the light source unit to the outside. A temperature sensing unit for changing a state of the signal output according to the temperature of the light source unit, a temperature sensing unit for determining a state according to the operation of the light source, and a temperature sensing unit for changing a state of the signal output according to the temperature of the light source unit And an on / off signal having a state determined according to whether the light source is operated and a temperature sensing signal from the temperature sensing unit, and controlling the operation of the cooling apparatus according to the on / off signal and the temperature sensing signal. It includes a control unit.

The temperature sensing unit may be a thermistor, and the light source may be a light emitting diode.

The controller may be configured to operate the cooling device when it is determined that the light source is operating based on the on / off signal, and not to operate the cooling device when it is determined that the light source is not operated. Do.

The controller may control the operation of the cooling device in stages based on the detected temperature range according to the temperature detection signal.

The cooling device is a cooling fan, and the control unit may change the rotational speed of the cooling fan in stages based on the sensed temperature range.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right on" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A liquid crystal display, which is an example of a backlight device and a display device according to an exemplary embodiment of the present invention, will now be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a liquid crystal display according to an embodiment of the present invention, FIG. 2 is a block diagram of a liquid crystal display according to an embodiment of the present invention, and FIG. 3 is a liquid crystal according to an embodiment of the present invention. It is an equivalent circuit diagram of one pixel of a display device. 4 is a block diagram of a cooling unit according to an embodiment of the present invention.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal module 350 including a display unit 330 and a backlight unit 900, and an upper portion and a lower portion accommodating the liquid crystal module 350. Chassis 361, 362, and mold frame 364.

The display unit 330 includes a liquid crystal panel assembly 300, a plurality of gate carrier package (TCP) 410 and data TCP 510 attached thereto, and a gate printed circuit board attached to the corresponding TCPs 410 and 510. A printed circuit board (PCB) 450 and a data PCB 550.

The liquid crystal panel assembly 300 includes a lower panel 100, an upper panel 200, and a liquid crystal layer 3 interposed therebetween.

The lower panel 100 includes a plurality of display signal lines G ₁ -G _n , D ₁ -D _m , and the lower and upper panel 100, 200 includes display signal lines G ₁ -G _n , D ₁ -D _m ) and includes a plurality of pixels arranged in a substantially matrix form.

The display signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”) and a data line D for transmitting a data signal. ₁ -D _m ). The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each pixel includes a switching element Q connected to a display signal line G ₁ -G _n , D ₁ -D _m , and a liquid crystal capacitor C _LC and a storage capacitor C _ST connected thereto. It includes. The holding capacitor C _ST can be omitted as necessary.

The switching element Q, such as a thin film transistor, is provided in the lower panel 100, and the control terminal and the input terminal are three-terminal elements, respectively, with gate lines G ₁ -G _n and data lines D ₁ -D _m . The output terminal is connected to a liquid crystal capacitor (C _LC ) and a holding capacitor (C _ST ).

The liquid crystal capacitor C _LC has two terminals, the pixel electrode 190 of the lower panel 100 and the common electrode 270 of the upper panel 200, and the liquid crystal layer 3 between the two electrodes 190 and 270. It functions as a dielectric. The pixel electrode 190 is connected to the switching element Q, and the common electrode 270 is formed on the front surface of the upper panel 200 and receives a common voltage V _com . Unlike in FIG. 3, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 190 and 270 may be linear or rod-shaped.

The storage capacitor C _ST , which serves as an auxiliary part of the liquid crystal capacitor C _LC , is formed by overlapping a separate signal line (not shown) and the pixel electrode 190 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage V _com is applied to this separate signal line. However, the storage capacitor C _ST may be formed such that the pixel electrode 190 overlaps the front end gate line directly above the insulator.

A polarizer (not shown) for polarizing light is attached to an outer surface of at least one of the two display panels 100 and 200 of the liquid crystal panel assembly 300.

As shown in FIG. 1, the gate TCP 410 is attached to one edge of the lower panel 100 of the liquid crystal panel assembly 300, and a gate driving integrated circuit constituting the gate driver 400 is formed on the chip. Equipped with. The data TCP 510 is attached to the other edge of the lower panel 100 of the liquid crystal panel assembly 300, and a data driver integrated circuit constituting the data driver 500 is mounted in the form of a chip. The gate driver 400 and the data driver 500 may include the gate lines G ₁ -G _n and the data lines of the liquid crystal panel assembly 300 through signal lines (not shown) formed in the TCPs 410 and 510. D ₁ -D _m ) are each electrically connected.

The gate driver 400 applies a gate signal formed of a combination of the gate on voltage V _on and the gate off voltage V _off to the gate lines G ₁ -G _n , and the data driver 500 applies the data voltage. It is applied to the data lines D ₁ -D _m .

Unlike this, a driver integrated circuit chip constituting the gate driver 400 and the data driver 500 may be directly attached onto the display panel without using TCP (chip on glass, COG mounting method), and the gate driver 400 or the data driver 500 may be formed directly on the liquid crystal panel assembly 300 together with the switching element Q and the display signal lines G ₁ -G _n and D ₁ -D _m .

The gate PCB 450 is attached to the TCP 410 in the longitudinal direction in parallel to the lower panel 100, and a plurality of signal lines (not shown), electronic components, and the like for transmitting signals are formed thereon.

The data PCB 550 is attached to the TCP 510 in the longitudinal direction in parallel to the lower panel 100, and a plurality of signal lines (not shown), electronic components, and the like for transmitting signals are formed thereon.

The gray voltage generator 800 generates two sets of gray voltages related to the transmittance of the pixel and provides them to the data driver 500 as data voltages. One of the two sets has a positive value for the common voltage (V _com ) and the other set has a negative value.

1, 2, and 4, the backlight unit 900 is housed in a lower chassis 362 fixed to the upper chassis 361, and a light source unit mounted on a lower portion of the liquid crystal panel assembly 300. 960, a plurality of optical devices 908 located between the assembly 300 and the light source unit 960 and processing light from the light source unit 960, and cooling to discharge heat generated from the light source unit 960 to the outside. Part 970 is included. In addition, the backlight unit 900 includes a support frame 905 received in the lower chassis 362 to fix the light source unit 960 and support the optical apparatus 908. This support frame 905 is fixed with the mold frame 363.

The light source unit 960 includes a plurality of PCBs 962 on which the plurality of light emitting diodes 961 are mounted, and a heat radiating member 963 attached to the PCB 962 to radiate heat. The heat dissipation member 963 is preferably made of a thermally conductive material. Each PCB 962 is arranged horizontally in the long axis direction of the liquid crystal panel assembly 300, and a plurality of red, green, and blue light emitting diodes 961 are alternately mounted. In this case, the number of green light emitting diodes mounted on each PCB may be greater than the number of red or blue light emitting diodes, for example, about twice as many. However, the number of these light emitting diodes may vary as needed.

On the other hand, to implement color display, each pixel uniquely displays one of the three primary colors (spatial division) or each pixel alternately displays the three primary colors over time (time division) so that the desired color can be selected by the spatial and temporal sum of these three primary colors. To be recognized. 3 illustrates that each pixel includes a red, green, or blue color filter 230 in an area of the upper panel 200 corresponding to the pixel electrode 190. Unlike FIG. 3, the color filter 230 may be formed above or below the pixel electrode 190 of the lower panel 100.

In FIG. 1, the optical apparatus 908 is positioned between the assembly 300 and the light source unit 960, and light emitting parts having a predetermined size are formed at regular intervals, and reflecting plates reflecting light emitted from the light emitting parts downwardly. 904 and a light blocking film 903 mounted on the reflecting plate 904 and formed at a portion facing the light emitting diodes 961 and uniformizing the intensity of light emitted through each of the light emitting diodes 961. And a diffuser plate 902 and at least one optical sheet 901 for guiding and diffusing light from the light guide plate 903 into the assembly 300.

In FIG. 1, the light emitting portion formed in the reflecting plate 904 has a circular shape in which each light emitting diode 961 can protrude, but has a size and shape, for example, a slit, in which a predetermined number of light emitting diodes can protrude simultaneously. It may have various sizes and shapes, such as shapes. The inner side of the support frame 905 is inclined at an angle to reflect light upwards.

The cooling unit 970 is mounted between the lower portion of the light source unit 960 and the lower chassis 936, but the mounting position of the cooling unit 970 may be changed as necessary.

Although not shown in FIG. 1, an upper case and a lower case are positioned at an upper portion of the upper chassis 361 and a lower portion of the lower chassis 362, respectively, to form a liquid crystal display device by combining them.

The signal controller 600 controls operations of the gate driver 400 and the data driver 500.                     

The display operation of such a liquid crystal display device will now be described in detail.

The signal controller 600 is configured to control the input image signals R, G, and B and their display from an external graphic controller (not shown), for example, a vertical synchronization signal Vsync and a horizontal synchronization signal ( Hsync, main clock MCLK, and data enable signal DE are provided. The signal controller 600 properly processes the image signals R, G, and B according to the operating conditions of the liquid crystal panel assembly 300 based on the input image signals R, G, and B and the input control signal, and controls the gate control signal. After generating the CONT1, the data control signal CONT2, the backlight control signal CONT3, and the like, the signal controller 600 then emits the gate control signal CONT1 to the gate driver 400 and the data control signal CONT2. The processed image signal DAT is sent to the data driver 500 and the backlight control signal CONT3 is sent to the backlight unit 900.

The gate control signal (CONT1) is such as at least one clock signal for controlling the output time and the output voltage of the start scan to indicate the start of output of a gate-on voltage (V _on) signal (STV), a gate-on voltage (V _on) Include.

The data control signal CONT2 includes a horizontal synchronization start signal STH indicating the start of transmission of the image data DAT, a load signal LOAD for applying a data voltage to the data lines D ₁ -D _m , and a common voltage V. _com ), the inversion signal RVS and the data clock signal HCLK for inverting the polarity of the data voltage with respect to the _com voltage (hereinafter, referred to as the polarity of the data voltage by reducing the polarity of the data voltage with respect to the common voltage).

The backlight control signal CONT3 is an on / off signal for controlling the blinking of the light source 960 and a pulse width modulation (PWM) signal for controlling the blinking of the light emitting diode of the light source 960. And a plurality of control signals such as a light source control signal.

Unlike the embodiment of the present invention, the backlight control signal CONT3 may be generated by a separate control device.

The data driver 500 sequentially receives and shifts the image data DAT for one row of pixels according to the data control signal CONT2 from the signal controller 600, and the gray voltage from the gray voltage generator 800. The grayscale voltage corresponding to each image data DAT is selected to convert the image data DAT into a corresponding data voltage, and then apply the grayscale voltage to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage V _on to the gate lines G ₁ -G _n in response to the gate control signal CONT1 from the signal controller 600, thereby applying the gate lines G ₁ -G _n. ) Turns on the switching element Q connected thereto, so that the data voltage applied to the data lines D ₁ -D _m is applied to the corresponding pixel through the turned-on switching element Q.

The difference between the data voltage applied to the pixel and the common voltage V _com is shown as the charging voltage of the liquid crystal capacitor C _LC , that is, the pixel voltage. The liquid crystal molecules vary in arrangement depending on the magnitude of the pixel voltage.

The light source unit 960 operates under the control of the backlight control signal CONT3 to perform flashing operations of the red, green, and blue LED strings.

According to the operation of the backlight unit 900, the light emitted from each light emitting diode string passes through the liquid crystal layer 3, and its polarization changes according to the arrangement of the liquid crystal molecules. This change in polarization is represented by a change in the transmittance of light by the polarizer.

The cooling unit 970 controls the operation state of the cooling fan 973 according to the operation state of the light source unit 960 when the light source unit 960 operates. The operation of the cooling unit 970 will be described in detail below.

After one horizontal period (or 1H) (one period of the horizontal synchronization signal Hsync) passes, the data driver 500 and the gate driver 400 repeat the same operation for the pixels in the next row. In this manner, the gate-on voltages V _{on are} sequentially applied to all the gate lines G ₁ -G _n during one frame to apply data voltages to all the pixels. When one frame ends, the next frame starts and the state of the inversion signal RVS applied to the data driver 500 is controlled so that the polarity of the data voltage applied to each pixel is opposite to that of the previous frame (frame inversion). . In this case, the polarity of the data voltage flowing through one data line may be changed (row inversion or dot inversion) or the polarity of the data voltage applied to one pixel row may be different according to the characteristics of the inversion signal RVS within one frame. (Heat inversion, dot inversion).

Next, the cooling unit 970 according to the exemplary embodiment of the present invention will be described in detail with reference to FIG. 5 in addition to FIG. 4 described above.                     

As shown in FIG. 4, the cooling unit 970 includes a temperature sensing unit 971, a control unit 972 connected to the temperature sensing unit 971 and a cooling fan connected to the control unit 972, to which an on / off signal is applied. 973).

The temperature detector 971 is a temperature sensor such as a thermistor in which an internal resistance value is changed according to the ambient temperature and the magnitude of the output electrical signal is determined, but other types of temperature sensors may be used.

The operation of the cooling unit 970 will be described in detail with reference to FIG. 5.

First, the temperature detector 971 detects an ambient temperature and transmits a signal having a corresponding magnitude, for example, a voltage, to the controller 970.

The control unit 972 receives a signal from the temperature sensing unit 971 and receives an on / off signal for controlling the lighting and turning off of the light source unit 960 (S11).

Then, the control unit 972 first determines the state of the on / off signal to determine whether the current state of the light source unit 960 is an on state, that is, an operating state (S12).

When the state of the on / off signal is an off state, that is, the light source unit 960 is in an inoperative state, the control unit 972 does not operate the cooling fan 973 (S14).

However, when the on / off signal is in an on state, that is, when the light source unit 960 is in an operating state, the controller 972 reads a detection signal from the temperature detector 971 to sense a temperature around the light source unit 960. (S13). Then, the controller 972 controls the rotation speed of the cooling fan 973 based on the sensed temperature (S15).

For example, the rotational speed of the cooling fan 973 may be gradually added or subtracted according to the sensed temperature range, or the rotational speed of the cooling fan 973 may also be changed in proportion to the change of the sensed temperature.

In this case, the controller 972 may be an inverter controller, or may be a controller separate from the inverter controller.

According to the present invention, since the operation of the cooling apparatus is controlled not only in the operating state of the light source unit but also in the ambient temperature, the cooling effect is increased and unnecessary power consumption is reduced. In addition, since unnecessary cooling devices are eliminated, noise is reduced and life is extended.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (12)

A light source unit having a light source, Cooling device for discharging the heat generated from the light source to the outside, A temperature sensor for changing the state of the signal output according to the temperature of the light source unit, and A control unit configured to control an operation of the cooling device according to the on / off signal and the temperature detection signal, and an on / off signal whose state is determined according to the operation of the light source and the temperature detection signal are input. Backlight device comprising a. In claim 1, The temperature sensing unit is a backlight device. In claim 1, The light source is a light emitting diode. In claim 1, The control unit operates the cooling device when it is determined that the light source is operating based on the on / off signal, and does not operate the cooling device when it is determined that the light source is not operating. . In claim 1, The control unit controls the operation of the cooling device step by step based on the temperature range detected according to the temperature detection signal. In claim 5, The cooling device is a cooling fan, The controller is configured to change the rotational speed of the cooling fan in stages based on the sensed temperature range. A plurality of pixels arranged in a matrix form, A light source unit including at least one light source for supplying light to the pixel; Cooling device for discharging the heat generated from the light source to the outside, A temperature sensor for changing the state of the signal output according to the temperature of the light source unit, and A control unit configured to control an operation of the cooling device according to the on / off signal and the temperature detection signal, and an on / off signal whose state is determined according to the operation of the light source and the temperature detection signal are input. Display device comprising a. In claim 7, And the temperature sensing unit is a thermistor. In claim 7, The light source is a light emitting diode. In claim 7, The control unit operates the cooling device when it is determined that the light source is operating based on the on / off signal, and does not operate the cooling device when it is determined that the light source is not operating. . In claim 7, The control unit controls the operation of the cooling device in stages based on the detected temperature range according to the temperature detection signal. In claim 7, The cooling device is a cooling fan, The control unit changes the rotational speed of the cooling fan in stages based on the sensed temperature range.

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