CN1842923A - Drive device for back light unit and drive method therefor - Google Patents
Drive device for back light unit and drive method therefor Download PDFInfo
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- CN1842923A CN1842923A CNA2005800008619A CN200580000861A CN1842923A CN 1842923 A CN1842923 A CN 1842923A CN A2005800008619 A CNA2005800008619 A CN A2005800008619A CN 200580000861 A CN200580000861 A CN 200580000861A CN 1842923 A CN1842923 A CN 1842923A
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Abstract
A drive unit for a back light unit (20) having a plurality of LED (Light Emission Diode) elements concatenated for each of three primary colors, comprising a signal generating unit (44) for generating a signal with an arbitrary amplitude, a unit (50) for regulating the light emitting quantities of LED element groups (30) based on a signal generated by the signal generating unit (44), a voltage applying unit (41) for applying a specified voltage to each of LED element groups (30), a light emitting quantity detection unit (33) for detecting a light quantity emitted from an LED element group (30) according to a voltage applied by the voltage applying unit (41), a calorie detection unit (32) for detecting calorie emitted from an LED element group (30), and a control unit (50) for controlling the signal generating unit (44) based on a light emitting quantity detected by the light emitting quantity detection unit (33) and calorie detected by the calorie detection unit (32).
Description
Technical field
The present invention relates to suitable drive unit and the driving method of carrying out the drive controlling of the back light unit of forming by many groups LED element.
The application requires the priority of Japanese patent application No.2004-205146 that submitted on July 12nd, 2004 and the Japanese patent application No.2004-336373 that submitted on November 19th, 2004, combines the full content of these patent applications here by reference.
Background technology
In using the display device of LED (light-emitting diode) element,, need be used for the X-Y addressing drive circuit of each pixel in order to carry out the matrix driving operation of LED element as display pixel.Display device is used to utilize the addressing drive circuit to carry out being positioned at the LED selection of components (addressing) that hope is launched the locations of pixels place of (lighting), in order to modulating the time of lighting with for example PWM (pulse-width modulation) drive system, thereby carry out briliancy (luminance) adjustment, to obtain to have Showing Picture of predetermined gray scale (gradation).
But, when drive circuit be at independent LED assemble the time, under the situation of LED huge amount, it is complicated that circuit arrangement becomes, so cost improves.
On the other hand, proposed and study and use the LED element as the backlight liquid crystal display light source.Particularly, because following method can easily realize color balance: the LED element that is respectively red (R), green (G) and blue (B) primary colors is used for optically carrying out synthetic addition colour mixture individually to obtain white light, and therefore such method is studied the display device as telecvision picture receiver widely.
Simultaneously, LED has the inhomogeneities of brightness value individually.When attempting to proofread and correct these independent inhomogeneities, must utilize independent driving circuits to drive each independent element one by one.So, drive form become that the utmost point is similar to and previously described use LED element as the form of the corresponding matrix type drive system of the display device of display pixel.That is, under the huge situation of LED component number, adopt the drive circuit of addressing will become very complicated.
In addition, be used as at the element such as the LED element under the situation of back light of liquid crystal display, because being respectively the luminous coefficient of the LED element of red (R), green (G) and blue (B) primary colors differs from one another, therefore also must be at each color, adjustment will be provided to the electric current of the LED element of each color.In addition, in the LED element, because forming, the semiconductor of each color elements differs from one another, so the voltage of each color elements and power consumption differ from one another.
In addition, drive in the side circuit of operation having powerful each LED element and be used to LED for the illumination purpose, owing to also do not prepare at the LSI of high-power driving etc., so the cost of matrix type drive system improves, thereby has shortcoming economically.
Given this, proposed following method: the type of attachment of LED element is used the form that connects as cascade, so that can not make that circuit scale is too big.In the cascade type of attachment, based on synthesizing of the light that sends from redness, green and blue LED element, electric current in certain series of LED connection group (for example the red, green and blue look LED element of each color be formed by connecting group) is carried out PWM adjust, to adjust the color harmony briliancy.
In adopting the back light unit of cascade type of attachment as the type of attachment of LED element, the DC-DC inverter power supply unit that is used for carrying to every group of redness, green and the blue-led element of cascade connection predetermined voltage is provided, and provides LED-PWM control unit in load-side.
Simultaneously, in above-mentioned configuration, because the temperature dependency of the luminous output of each color system is also different, and temperature characterisitic is inconsistent, therefore need utilize the drive circuit of each color specific that the pulsewidth of every kind of color is carried out adjustment.
For example, just lighted under the situation that temperature does not rise fully afterwards backlight, the LED element of redness with high-luminous-efficiency is luminous in time of about 50% of ON time of the driving pulsewidth of pwm signal, and the LED element with low luminous efficiency is luminous in time of about 80～90% of ON time of the driving pulsewidth of pwm signal.
Because the light that sends from the LED element has such attribute, therefore must guarantee to remain unchanged by the tone (colour temperature and colourity) and the briliancy of the synthetic white light that obtains from the light of red, green and blue-led element emission, thereby utilize light sensors respectively from the light of red, green and blue-led element emission to carry out feedback servo, so that detected like this value becomes constant.
In such reponse system, for example under the coarse situation of the resolution of the change of the pulsewidth that is used to control pwm signal, to cause adjusting the difference of accuracy, the feasible number of cutting apart that depends between 0% to 100%, change width roughening under the situation of red LED element, under the situation of blue-led element, become meticulous with poor (low) luminous efficiency and change width with good (height) luminous efficiency.
In addition, since from the color of the light of LED element emission because the difference of the resolution of each color system and have uneven accuracy, therefore to the adjustment of RGB balance and/or to the adjustment of the white light difficulty that becomes at each color.
In addition, even the problems referred to above all can be solved, the luminous output of the LED element of each color and luminescent spectrum distribute and all change with the temperature change in the LED element of each color, thereby the luminescent chromaticity of each color is changed.Therefore, under the situation of the method for the light quantity that only adopts the LED element that utilizes optical sensor to detect each color, the change that can't proofread and correct tone.Have at back light unit under the situation of Temperature Distribution (for example on the direction up and down when it drives operation), will colour inhomogeneous based on this temperature contrast be taken place.As mentioned above, the temperature characterisitic of the luminescence distribution of the performance of optical sensor and/or LED element is to keeping a restriction of accuracy, making that the colourity control deviation approximately is Δ x ≈ 0.002 and Δ y ≈ 0.002.
Summary of the invention
The problem to be solved in the present invention:
The present invention proposes in view of the problem that above-mentioned prior art has, its purpose is to be provided for the drive unit and the driving method of back light unit, this drive unit and driving method are suitable for one or more calorific values and the luminous quantity based on the LED element group that constitutes back light unit, and control is used to make the luminous driver element of LED element group.
Drive unit according to the present invention is at a kind of drive unit that is used to comprise the back light unit of LED (light-emitting diode) element group, in described LED element group, a plurality of LED elements connect with every trichromatic mode cascade, described drive unit comprises: signal generating apparatus is used to generate the signal with any amplitude; Adjusting device is used for based on the luminous quantity of being adjusted LED element group by the signal of signal generating apparatus generation; Voltage supply device is used for to each LED element group supply predetermined voltage; The luminous quantity checkout gear, be used to detect according to by the voltage of voltage supply device supply from the amount of the light of LED element group emission; Temperature-detecting device is used to detect one or more temperature of LED element group; And control device, be used for based on by the detected luminous quantity of luminous quantity checkout gear with by the detected one or more temperature of temperature-detecting device, control signal generating apparatus.
In addition, driving method according to the present invention is a kind of driving method that is used to comprise the back light unit of LED (light-emitting diode) element group, in described LED element group, a plurality of LED elements connect with every trichromatic mode cascade, described driving method comprises: voltage supply step, and this step is fed to each LED element group with predetermined voltage; Luminous quantity detects step, and this step detects according to the voltage that is provided by voltage supply step and from the amount of the light of LED element group emission; The temperature detection step, this step detects one or more temperature of LED element group; Signal generates step, and this step is based on being detected the detected luminous quantity of step and by the detected one or more temperature of temperature detection step, generated the signal with any amplitude by luminous quantity; And set-up procedure, this step is adjusted the luminous quantity of LED element group based on the signal that is generated by signal generation step.
In drive unit according to the present invention and driving method, be used as in the system of LED element of LCD backlight in driving, the testing result of the optical sensor relevant with random color is caught the reference as other colors of monitoring, to carry out the feedback of relevant percentage (ratio), and testing result based on temperature sensor, change the ratio of experience feedback, thereby make the on all four control of execution become possibility.
From the embodiment that describes below with reference to the accompanying drawings, other purposes of the present invention and the advantage that obtains by the present invention will become clearer.
Description of drawings
Fig. 1 is the stereogram that the color liquid crystal display arrangement of the back light system that the present invention is applied to is shown with model form.
Fig. 2 is the block diagram that the drive circuit of color liquid crystal display arrangement is shown.
Fig. 3 is the plane graph that the layout example of employed light-emitting diode in the back light unit that constitutes color liquid crystal display arrangement is shown.
Fig. 4 utilizes the diode mark of circuit diagram symbol that the figure of the type of attachment of each light-emitting diode in the layout example of light-emitting diode is shown with model form.
Fig. 5 is the pattern symbol that utilizes according to the light-emitting diode sequence number of each color, with model form the figure of cell cube (unit cell) is shown, and six light-emitting diodes are arranged in rows altogether in this cell cube.
Fig. 6 is the pattern symbol that utilizes according to the light-emitting diode sequence number, and the figure of the situation that three cell cubes of serving as elementary cell are connected in succession is shown with model form.
Fig. 7 is the figure of actual connection example that the light-emitting diode of the light source that constitutes back light unit is shown with model form.
Fig. 8 is the figure that is illustrated in the connection example of the light-emitting diode that uses in the back light unit with model form.
Fig. 9 is the figure that the Temperature Distribution of display unit is shown with model form.
Figure 10 is the figure that the Temperature Distribution of the connection status of the light-emitting diode in the back light unit and display unit is shown with model form.
Figure 11 is used to illustrate the figure that is used for from the processing of the temperature of a temperature sensor and each position of Temperature Distribution model estimation.
Figure 12 is the block diagram that the drive circuit that is used for the driven for emitting lights diode is shown.
Figure 13 is the figure that is used to illustrate from the temperature characterisitic of the light of each LED element emission.
Figure 14 illustrates with respect to the wavelength shift of the temperature change of each LED element and the performance plot of resultant brightness (brightness) characteristic.
Figure 15 illustrates when the light from the emission of each LED element to be combined with the figure of the synthetic addition colour mixture of optically the carrying out back light unit white chromaticity distortion when obtaining white light.
Figure 16 A and Figure 16 B illustrate by optically carrying out the figure of the data that optics output balance obtains.
Figure 17 is the block diagram that the configuration of back light unit is shown.
Figure 18 A, Figure 18 B and Figure 18 C are the figure that is used to illustrate the resolution of pwm signal.
Figure 19 A, Figure 19 B and Figure 19 C are the figure of waveform that the pwm signal of the LED element group that is transported to each color is shown.
Figure 20 A, Figure 20 B and Figure 20 C are the figure of actual example of waveform that the pwm signal of the LED element group that is transported to each color is shown.
Embodiment
Describe embodiments of the invention below with reference to the accompanying drawings in detail.
The present invention for example is applied to has the color liquid crystal display arrangement 100 of the back light system of configuration as shown in Figure 1.
Color liquid crystal display arrangement 100 as shown in Figure 1 comprises transmission (transmission) formula color liquid crystal display panel 10 and is set at the back light unit 20 of color liquid crystal display panel 10 back one side.
Transmission-type color liquid crystal display panel 10 has following configuration: TFT substrate (substrate) 11 and reverse electrode substrate (substrate) 12 are arranged relative to one another, and liquid crystal layer 13 is set in the interval between two substrates, for example is filled with twisted nematic (TN) liquid crystal in described liquid crystal layer 13.On TFT substrate 11, be formed with holding wire 14 and scan line 15 with matrix arrangement, and as the thin-film transistor 16 of switch element be arranged in the pixel electrode 17 at its place, crosspoint.Thin-film transistor 16 is scanned line 15 selective sequentials, and is used for being written to corresponding pixel electrode 17 with transmitting the vision signal of coming from holding wire 14.On the other hand, reverse electrode 18 and colour filter 19 are formed on the inner surface of reverse electrode substrate 12.
Color liquid crystal display arrangement 100 fitted to be the transmission-type color liquid crystal display panel 10 with this configuration is placed between two polarising sheets, with by back light unit 20 from behind in the state of side irradiation white light, utilize active matrix system to carry out and drive operation, show thereby can obtain required full-color image.
The color liquid crystal display arrangement 100 that the present invention is applied to is for example driven by the drive circuit 200 with circuit arrangement shown in Figure 2.
In drive circuit 200, by RGB process control unit 150, the vision signal Vi by internal terminal 140 input is caught to experience the signal processing such as colourity processing etc.In addition, processed video signal Vi is converted to the RGB separation signal of the driving operation that is suitable for color liquid crystal display panel 10 from composite signal like this.The RGB separation signal of Huo Deing is passed to control unit 170 like this, and is passed to X driver 120 by video memory 160.In addition, control unit 170 utilizes the RGB separation signal that is transported to X driver 120 by video memory 160, with scheduled timing control X drive circuit 120 and Y drive circuit 130 corresponding to the RGB separation signal, drive color liquid crystal display panel 10, to show and the corresponding image of RGB separation signal.
Then, the layout at the light-emitting diode at light source 21 places of back light unit 20 will be illustrated.
Fig. 3 illustrates following state: as the layout example of light-emitting diode, in each cell cube 4-1,4-2, use two red light emitting diodes 1, two green LEDs 2 and two blue LEDs 3 respectively, thereby six light-emitting diodes are arranged in rows altogether.
Though in this layout example, provide six light-emitting diodes as cell cube 4, but the distribution of each number of color may be different from this example according to the needs of adjusting light output balance, and this is to have well balanced white light because the color of mixing is caught to become according to the grade of employed light-emitting diode and/or luminous efficiency etc.
In layout example shown in Figure 3, cell cube 4-1 and cell cube 4-2 have identical configuration, and their two ends at the center are continuous, and be indicated as arrow.In addition, Fig. 4 shows the example that the diode mark that utilizes the circuit diagram symbol comes the type of attachment of illustrated cell body 4-1 and cell cube 4-2.Under the situation of this example, each light-emitting diode (i.e. Hong Se light-emitting diode 1, green light-emitting diode 2 and blue light-emitting diode 3) has at them to be followed electric current and from left to right is connected in series under the state of the polarity of flow direction.
Here, carry out when the number of the light-emitting diode that utilizes each color cell cube 4 (has wherein been used two red light emitting diodes 1, two green LEDs 2 and two blue LEDs 3 respectively, thereby six light-emitting diodes are arranged in rows altogether) the pattern note time, it is represented as ( 2G 2R 2B), as shown in Figure 5.That is, ( 2G 2R 2B) illustrates: six patterns altogether that are made of two green patterns, two red pattern and two blue patterns are caught as elementary cell.In addition, under the situation of three cell cubes that connect elementary cell as shown in Figure 6 in succession, when utilizing the number of light-emitting diode to carry out the pattern note according to the symbol that is represented as 3* ( 2G 2R 2B), these cell cubes are indicated with ( 6G 6R 6B).
Then, the annexation at the light-emitting diode at light source 21 places of back light unit 20 will be illustrated.
As shown in Figure 7, at light source 21 places, the big three times elementary cell of elementary cell (2G2R 2B) than previously described light-emitting diode is caught as a temporary location ( 6G 6R 6B), thereby a plurality of temporary locations ( 6G 6R 6B) are arranged with matrix form, this matrix has the five-element on the horizontal direction with respect to screen, four row are arranged in vertical direction.So, 360 light-emitting diodes have been arranged altogether.These temporary locations ( 6G 6R 6B) are electrically connected on the horizontal direction of screen, and light-emitting diode is arranged on the horizontal direction of screen.As mentioned above, at light source 21 places of back light unit 20, the temporary location that is electrically connected on the horizontal direction of screen ( 6G 6R 6B) is connected in series, as shown in Figure 8.Like this, a plurality of groups 30 that constitute by a plurality of light-emitting diodes that are connected in series have in the horizontal direction been formed.
In addition, at back light unit 20 places, provide independently led drive circuit 31 one by one respectively by the group 30 that the light-emitting diode that is connected in series in the horizontal direction constitutes to each.Led drive circuit 31 is to be used for allowing electric current to flow so that their luminous circuit in the group 30 of light-emitting diode.
Here, there is following state in layout for the group 30 of the light-emitting diode that is connected in series in the horizontal direction: the light-emitting diode that wherein is disposed in certain zone is connected to each other, in described zone, when measuring the Temperature Distribution of back light unit 20, each LED has essentially identical temperature.
When operation back light unit 20, the Temperature Distribution example on the screen of color liquid crystal display arrangement 100 as shown in Figure 9.The part that shade shown in Fig. 9 is dense is a high-temperature area, and the light part of shade is a low-temperature region.As shown in Figure 9, in color liquid crystal display arrangement 100, along with the distance to picture top Su shortens and temperature uprises, it is higher that temperature becomes, and screen bottom Sd has low temperature.
Among the figure of Figure 10, the figure of the annexation of indication light-emitting diode and the temperature profile of Fig. 9 overlap each other among Fig. 8.As shown in figure 10, in this example, when the light-emitting diode of arranging on the horizontal direction at screen was connected, the light-emitting diode with basic identical temperature was connected to each other.
In addition,, as shown in figure 10, provide temperature sensor 32, be used to detect the temperature of each light-emitting diode group 30 at back light unit 20 places.
As temperature sensor 32, as shown in figure 10, can with corresponding each upright position of group of the light-emitting diode gone up in the horizontal direction of being connected in series on a plurality of LED are set respectively, perhaps can a LED only be set at back light unit 20 places.In addition, as shown in figure 11, for example, back light unit 20 can be caught to have following configuration: a temperature sensor 32 is set and memory (has wherein been stored the Temperature Distribution pattern on the screen vertical direction in advance in screen center, example is memory 49 as will be described later), with by the content of reference, estimate the temperature of each position on the screen vertical direction from the detected value of a temperature sensor 32.The temperature value that is detected by temperature sensor 32 is transported to the led drive circuit 32 that is used to drive corresponding light-emitting diode group.
In addition, at back light unit 20 places, as shown in figure 10, for example provide the light quantity of the light quantity of each color R of being used for detecting each light-emitting diode group 30, G, B or colourity or chromaticity transducer 33 (33R, 33G, 33B).
As shown in figure 10, (33R, 33G 33B) are set on group 30 corresponding each upright positions with the light-emitting diode that is connected in series in the horizontal direction for a plurality of light quantities or chromaticity transducer 33.In addition, can adopt following optical system: wherein be used to allow the slow fire plate of whole blend of colors unanimity to wait the blend of colors etc. of the light of carrying out each LED emission effectively, (33R, 33G, number 33B) have only one to allow light quantity or chromaticity transducer 33.
Note, be used as at LED under the situation of back light of liquid crystal, has following example: wherein light quantity or chromaticity transducer 33 for limit former of layout and shape thereby can not be placed on light-emitting diode group 30 near.Under light quantity or chromaticity transducer 33 were placed on situation away from the part of light-emitting diode group 30, they will detect as the low light level from the light of light-emitting diode group 30 emissions.Under light quantity or chromaticity transducer 33 were placed on situation near the part of light-emitting diode group 30, they will detect as high light from the light of light-emitting diode group 30 emissions.In the case, by utilizing with reference to execution optics emulation or actual measurements such as light-emitting diodes, calculate the characteristic of light quantity or chromaticity transducer 33, with its correcting value data that is prepared in advance as memory table, thereby proofread and correct the light quantity data of sensing based on this correcting value data, make like this and can comply with this situation or inconvenience.
Then, the led drive circuit 31 that is used to drive the light-emitting diode group 30 that is connected in series in the horizontal direction will be illustrated.In the case, led drive circuit 31 is set in the backlight drive control unit 180.
The circuit arrangement example of led drive circuit 31 as shown in figure 12.
FET 46, resistor 47, maintenance timing circuit 48, memory 49 and CPU (CPU) 50 that led drive circuit 31 comprises DC-DC converter 41, constant resistance device (Rc) 42, FET 43, pwm control circuit 44, capacitor 45, is used to sample and keeps.
Led drive circuit 31 is provided to one or more temperature sensors 32 and light quantity or chromaticity transducer 33 (33R, 33G, detection output valve 33B).
DC-DC converter 41 is provided to from the dc voltage V of light source shown in Figure 2 110 generations
IN, carry out handover operation with DC electric power, to generate stable DC output voltage V cc to input.DC-DC converter 41 generates stable output voltage V cc, and making becomes from the voltage of feedback terminal Vf input and the electrical potential difference between the output voltage V cc equals reference voltage level (Vref).In this example, reference voltage level (Vref) transmits from CPU 50.
The anode-side of the group 30 of the light-emitting diode that is connected in series is connected to the lead-out terminal of the output voltage V cc of DC-DC converter 41 by constant resistance device (Rc).In addition, the anode-side of the group 30 of the light-emitting diode that is connected in series is connected to the feedback terminal of DC-DC converter 41 by source electrode-drain electrode that sampling keeps FET 46.The cathode side of the group 30 of the light-emitting diode that is connected in series in addition, is ground connection by the part (raceway groove) between source electrode and the drain electrode.
The grid of FET 43 is provided to the pwm signal that generates from pwm control circuit 44.When pwm signal is in the ON state, part (raceway groove) conducting between the source electrode of FET 43 and the drain electrode.When pwm signal was in the OFF state, the part (raceway groove) between source electrode and the drain electrode was turned off.Therefore, when pwm signal was in the ON state, FET 43 allowed electric current to flow in light-emitting diode group 30.When pwm signal was in the OFF state, FET 43 made the electric current that flows in light-emitting diode group 30 become 0.That is, when pwm signal was in the ON state, FET 43 made light-emitting diode group 30 luminous.When pwm signal was in the OFF state, FET 43 stopped the luminous light emission operation of light-emitting diode group 30.
Pwm control circuit 44 generates pwm signal, and this pwm signal is a kind of binary signal, and wherein ON time and the duty ratio of OFF between the time can be adjusted.Pwm control circuit 44 is provided to the PWM controlling value from CPU 50, to change duty ratio according to the PWM controlling value.
Keep timing circuit 48 to be provided to pwm signal, to generate inhibit signal, this inhibit signal only is switched to one period scheduled time of OFF at the rising edge of pwm signal, all switches to ON at other times.
Sampling keeps the grid of FET 46 to be provided to from keeping the inhibit signal of timing circuit 48 outputs.When inhibit signal was in the OFF state, sampling kept the source electrode of FET 46 and part (raceway groove) conducting between the drain electrode.When inhibit signal was in the ON state, sampling kept the source electrode of FET 46 and the part (raceway groove) between the drain electrode to be turned off.
In aforesaid led drive circuit 31, only being in time period of ON state, the pwm signal that generates from pwm control circuit 44 makes electric current I
LEDIn light-emitting diode group 30, flow.In addition, capacitor 45, sampling keep FET 46 and resistor 47 to constitute sampling hold circuit.This sampling hold circuit be used for when pwm signal is in the ON state to light-emitting diode group 30 anode (, an end that is not provided output voltage V cc of constant resistance device 42) magnitude of voltage sampling, thus the magnitude of voltage that will sample like this is transported to the feedback terminal of DC-DC converter 41.Because DC-DC converter 41 based on the magnitude of voltage that is imported into feedback terminal, makes output voltage V cc stable, therefore the electric current I that flows in constant resistance device Rc 42 and light-emitting diode group 30
LEDSummit (peak) value become constant.
Therefore, in led drive circuit 31, in the electric current I that flows through light-emitting diode group 30
LEDThe constant state of summit (peak) value in carry out and the corresponding pulsed drive operation of pwm signal.
Can be by changing the PWM controlling value to be adjusted at the duty ratio of the electric current that flows in the light-emitting diode group 30, can be transported to the reference voltage level (Vref) of DC-DC converter 41 to be adjusted at summit (peak) value of the electric current that flows in the light-emitting diode group 30 by change, perhaps can carry out adjustment by the combination of these methods of adjustment to value of current flowing in light-emitting diode group 30.
As mentioned above, CPU 50 is based on one or more temperature sensors 32 and light quantity or chromaticity transducer 33 (33R, 33G, 33B) both detection signals, the light intensities that light-emitting diode group 30 is luminous are carried out FEEDBACK CONTROL, be created on the white light that has even color and briliancy in the image and become possibility thereby make.
Here, the detection output valve of serviceability temperature transducer 32 reason of controlling the intensity of lumination of light emitting diode will be illustrated.
At first, the temperature characterisitic of LED element will be described referring to figs. 13 through Figure 15.
Figure 13 is the figure that each redness (R), green (G) and the relative brightness value of blue (B) LED element are shown.In the figure of Figure 13, indication LED component temperature on the x direction of principal axis, the relative briliancy of indication on the y direction, and to make the relative briliancy at 25 ℃ of points of component temperature place be 100%.
Red (R) LED element has the layered semiconductor structure of the quaternary prime system system of AlInGaP.Because band-gap energy is low, therefore reduce when the high temperature for luminous contributive charge carrier.Therefore, the light quantity that is launched is lowered.So, under common about 70 ℃ state as operation (work) temperature of LED element, brightness value be lowered to when being set to normal temperature for 25 ℃ about 60%.In addition, in the LED element of red (R), brightness value is bigger than other colors with respect to the change of temperature.
On the other hand, in green (G) the LED element and blueness (B) LED element of the layered semiconductor structure of the element system with InGaN, these LED elements have than the shorter wavelength of red (R) LED element, so their color becomes more purple.Therefore, band-gap energy is very big.Therefore, these LED elements become and are difficult to be subjected to Temperature Influence.
As mentioned above, will be understood that the amount of the light of LED element is such, promptly the temperature characterisitic of different colours is different.
Figure 14 illustrates the figure of the brightness of each redness (R), green (G) and blue (B) LED element with respect to emission wavelength.Temperature be shown be the figure under each situations of 0 ℃, 25 ℃ and 50 ℃ among Figure 14.In the case, in the figure of Figure 14, on the x direction of principal axis, indicate emission wavelength, and indication luminous output (brightness) on the y direction of principal axis.
Figure 14 understands as reference, and in each LED element, not only luminous quantity changes with respect to temperature (zone of the part of being surrounded by curve), and wavelength rises towards long wavelength's one side translation with temperature.Particularly, in red (R) LED element, with the corresponding wavelength in chevron summit (peak) (peak wavelength) along with temperature rises towards long wavelength's one side translation.
From above-mentioned Figure 13 and Figure 14 as can be known, the temperature characterisitic of LED element depends on that each color has very big change.Particularly, will be understood that, blue (B) LED element has such characteristic: brightness value changes hardly with respect to temperature change, and wavelength is very little with respect to the change of temperature change, and on the other hand, red (R) LED element has such characteristic: brightness value is very big with respect to the change of temperature change, and wavelength is also very big with respect to the change of temperature change.
Figure 15 shows when being combined optically to carry out synthetic addition colour mixture when obtaining white light at back light unit 20 from the light of redness (R) LED element with above-mentioned characteristic, green (G) LED element and the emission of blueness (B) LED element, (the cie color coordinate shows the temperature deviation of (x, y)) to white colourity.In the case, characteristic shown in Figure 15 is measured under the state that the FEEDBACK CONTROL based on the light quantity of chromaticity transducer and temperature is stopped.As shown in figure 15, when temperature when 35 ℃ rise to 60 ℃, the colourity of white light has with lower deviation: the deviation of Y (Δ y value) become equal+0.0025, and the deviation of X (Δ x value) becomes and equals-0.015.The colourity that is appreciated that white is corresponding to following trend: in the characteristic of temperature change with respect to red (R) LED element shown in Figure 14, rise with temperature with the corresponding wavelength in chevron summit (peak) (peak wavelength) and towards long wavelength's one side translation.
The LED element has the said temperature characteristic.
Such LED element has very big temperature dependency, and their characteristic can depend on color and different.For this reason, require CPU 50 also to carry out control, so that permission is constant from tone (colour temperature and the colourity) maintenance of the white light of back light unit 20 emissions by serviceability temperature transducer 32.
In addition, in order to allow to keep constant from the tone (colour temperature and colourity) of the white light of back light unit 20 emission, CPU 50 need utilize optical sensors to detect each luminous quantity of each color of redness (R), green (G) and blue (B), with the luminous quantity of control synthetically red (R), green (G) and blueness (B).Promptly, do not adopt by the optical sensors of only reference red (R) and export the method for carrying out the FEEDBACK CONTROL of red (R) luminous quantity, but need be by exporting the FEEDBACK CONTROL of carrying out red (R) luminous quantity with reference to the optical sensors of all colours that also comprises other colors (red (R), green (G) and blue (B)).
Therefore, CPU 50 is based on representing to carry out computing (calculating) as the matrix operations that contain triplex row and three row with following formula (1) indication, with each color of comprehensive adjustment (R, G, the luminous quantity of LED element B).
[1]
Matrix A
…(1)
In formula (1), " X ", " Y " and " Z " representative are from the chromaticity coordinate of the light of back light unit 20 emissions.In addition, in formula (1), the detection output valve of the red component of " Lr " indication light quantity or chromaticity transducer 33, the detection output valve of the green component of " Lg " indication light quantity or chromaticity transducer 33, and the detection output valve of the blue component of " Lb " indication light quantity or chromaticity transducer 33.
In addition, the last matrix that is in formula (1) right side is the Coefficient m by triplex row * three row
XyThe matrix A that constitutes, this matrix A is detection output valve (Lr, Lg, coefficient matrix Lb) that is multiplied by light quantity or chromaticity transducer 33.(in the case, the subscript x of m is 1,2,3, and its indication is corresponding to the line of coefficients of this coefficient number, and the subscript y of m is 1,2,3, and its indication is corresponding to the coefficient row of this coefficient number.) matrix A should be represented as constant in the ideal case.But because as mentioned above, in fact the LED element of each color has temperature characterisitic, so matrix A is by multiply by the matrix that matrix B obtains with following Matrix C: Matrix C is by the constant j of triplex row * three row
XyExpression, and matrix B is by the function k of the temperature T of using the LED element as parameter
Xy(T) constitute, it is used to eliminate temperature characterisitic.
[2]
The Matrix C matrix B
…(2)
In other words, CPU 50 is based on formula (1), and (Lr, Lg Lb), carry out FEEDBACK CONTROL, so that the tone of white light (colour temperature and colourity) becomes constant to utilize the detection output (T) of temperature sensor 32 and the detection output of light quantity or chromaticity transducer 33.
In this example, as the function k of the component of matrix B
Xy(T) value and as the coefficient j of the component of Matrix C
XyFrom factory's shipment or before sending in advance by experiment or meter calculate, and to be stored in be in the memory 49 of nonvolatile memory.
The practical operation of the CPU 50 that is used to carry out above-mentioned computing (calculating) and controls is as described below.
At back light unit 20 duration of works, CPU 50 with the suitable time period (for example every the preset time section or free) carry out adjustment control to the colourity and the briliancy of back light unit 20.
When CPU 50 began adjustment control to the colourity of back light unit 20 and briliancy, it read the output of one or more temperature sensors 32 and light quantity or chromaticity transducer 33, and calls (reading) function k from memory 49
XyWith coefficient j
Xy
In addition, CPU 50 is adjusted at value of current flowing (PWM duty ratio or summit value) in the LED element of each color, so that the colourity (X that calculates like this, Y, Z) equal to be stored in value in memory 49 grades, in described memory 49, store the specific value of setting that is provided with or before sending, for example ideal value from factory's shipment.
Like this, CPU 50 allows the tone (colour temperature and colourity) of the white light launched from back light unit 20 to keep constant if having time in institute.
Figure 16 A is illustrated in only to utilize light quantity or chromaticity transducer 33 to carry out colourity control and do not utilize temperature sensor 32 to carry out under the situation of FEEDBACK CONTROL (situation of conventional method), (the cie color coordinate shows the temperature deviation of (x, y)) to the colourity of the white light of launching from back light unit 20.In addition, Figure 16 B is illustrated in to utilize both FEEDBACK CONTROL of temperature sensor 32 and light quantity or chromaticity transducer 33 to be performed with under the situation of carrying out colourity control (situation of method of the present invention), (the cie color coordinate shows the temperature deviation of (x, y)) to the colourity of the white light of launching from back light unit 20.
Shown in Figure 16 A, only utilizing light quantity or chromaticity transducer 33 to carry out under the situation of colourities control, Δ y value is+0.0010 and Δ x value is-0.0015, as the deviation in the scope from 25 ℃ to 50 ℃.Will be understood that this characteristic is compared with characteristic shown in Figure 15, improving 1/5 aspect the Δ y value, and improving 1/10 aspect the Δ x value.
In addition, utilize temperature sensor 32 and light quantity or chromaticity transducer 33 both carry out FEEDBACK CONTROL with the situation of carrying out colourity control under, shown in Figure 16 B, Δ y value is+0.0005 and Δ x value is-0.0005, as the deviation in the scope from 25 ℃ to 50 ℃.Will be understood that this characteristic is compared with characteristic shown in Figure 15, improving 1/2 aspect the Δ y value, and improving 1/3 aspect the Δ x value, therefore realized further characteristic improvement.
As mentioned above, the back light unit 20 that is applied to according to the present invention, because based on one or more temperature sensors 32 and light quantity or chromaticity transducer 33 (33R, 33G, 33B) both detection signals, the tone (colour temperature and colourity) of the white light that is launched and briliancy are caught constant, therefore can have the light of stable tone with the emission of high accuracy ground.
Then, will the configuration of backlight drive control unit 180 be described.As shown in figure 17, backlight drive control unit 180 comprises above-mentioned a plurality of led drive circuit 31, and led drive circuit 31 is provided to the voltage from power supply 110, and it is used for becoming dc voltage with driven for emitting lights diode group 30 the AC voltage transitions.
In Figure 17, the group of group g1 indication top line, it comprises red light emitting diodes group 30 (R1), green LED group 30 (G1) and blue LED group (B1).Group g2 indication is positioned at the group at delegation place below the group g1, and it comprises red light emitting diodes group 30 (R2), green LED group 30 (G2) and blue LED group 30 (B2).In addition, Figure 17 shows when pwm signal is transported to each row light-emitting diode group 30 with model form, drives the difference between the width.
Here, the PWM to light-emitting diode group 30 that is carried out by backlight drive control unit 180 drives and operates and will be illustrated.
At first, pay close attention to blue (B) LED element.Because blue (B) LED element is had any problem aspect luminous efficiency, therefore make ON time of pwm signal be caught light period, to supply or to compensate the deficiency of light quantity aspect greater than red (R) LED element and green (G) LED element.In addition, between the driving width of the pwm signal of the capable B2p of the driving width of the pwm signal of the capable B1p of g1 and g2, there are differences hardly.This be because since g1 capable at display position above g2 is capable, thereby have high-temperature, but be blue (B) LED element by the LED element paid close attention to, it is because the luminous change that temperature dependency causes is less, need not to make therefore that to drive width different.
Then, pay close attention to red (R) LED element.Because red (R) LED element has good illumination efficiency, thus the ON time period of pwm signal compare with blueness (B) LED element and be shortened.In addition, the difference k between the driving width of the pwm signal of the R2p that the driving width of the PWN signal of the R1p that g1 is capable and g2 are capable is very big.This be because since g1 capable at display position above g2 is capable, thereby temperature is very high, and is red (R) LED element by the LED element paid close attention to, therefore it must make that to drive width different because luminous quantity that temperature dependency causes changes greatlyyer.Backlight drive control unit 180 is carried out and is driven operation, so that the pulsewidth of the capable place of g1 pwm signal becomes when temperature is very high greatly, so that realization is with respect to the light quantity balance of other groups of going.
The difference that backlight drive control unit 180 fitted to be the ON time period that makes pwm signal is used as the technology that changes luminous quantity, so that the Temperature Distribution of display is consistent, thereby makes the consistency of guaranteeing temperature characterisitic in the display possibility that becomes.
Then, the operation that is used to adjust the resolution of each color will be illustrated.
Figure 18 A is the oscillogram that the resolution of pwm signal is shown to 18C.Figure 18 A shows the oscillogram of the pwm signal that is transported to redness (R) light-emitting diode group 30, Figure 18 B shows the oscillogram of the pwm signal that is transported to green (G) light-emitting diode group 30, and Figure 18 C shows the oscillogram of the pwm signal that is transported to blueness (B) light-emitting diode group 30.
As light from red (R) LED element emission, be adjusted to obtain predetermined this true result of white light from the light of green (G) LED element emission with from the mixing ratio of the light of blue (B) LED element emission, as Figure 18 A to shown in the 18C, can obtain predetermined white light when following mixing ratio occurring: the pulsewidth that wherein is transported to the pwm signal of blueness (B) light-emitting diode group 30 is 256 (about 100%), the pulsewidth that is transported to the pwm signal of green (G) light-emitting diode group 30 is 191 (about 75%), and the pulsewidth that is transported to the pwm signal of redness (R) light-emitting diode group 30 is 126 (about 50%).
In addition, in above-mentioned example, be set at the adjustment width of the pulsewidth of the pwm signal that is transported to each light-emitting diode group 30 under 8 the situation, be transported to blueness (B) light-emitting diode group 30 pwm signal pulsewidth the degree of freedom can with 1/256 the step (Step) adjust, shown in Figure 18 C.But, be transported to redness (R) light-emitting diode group 30 pwm signal pulsewidth the degree of freedom only with 1/126 the step (only about half of) adjust.In addition, there is following inconvenience: 1 step of pulsewidth that is transported to the pwm signal of blueness (B) light-emitting diode group 30 value of twice in 1 step of pulsewidth of the pwm signal that equals to be transported to redness (R) light-emitting diode group 30 that becomes.This is inconvenient from the angle of guaranteeing to adjust accuracy.
For fear of such inconvenience, must improve the resolution of adjusting width.For example, having the adjustment width of pulsewidth of the pwm signal of the light-emitting diode group 30 allow to be transported to blueness (B) is 10 technology.But, between the adjustment step number of each light-emitting diode group 30, there are differences.Owing to carry out to improve on principle, therefore when the difference of ON time period of pwm signal reaches 50%, the adjustment width of pulsewidth that is transported to the pwm signal of redness (R) light-emitting diode group 30 will be with the value deterioration corresponding to 1.In addition, become and equal 10 or when bigger when adjusting resolution, the converter that is used to carry out processing etc. becomes very expensive, thereby can improve the cost of equipment itself.
Given this, as Figure 19 A to shown in the 19B, backlight drive control unit 180 is adjusted and is transported to summit (peak) value (constant current value ILED) of the signal of each light-emitting diode group 30 from the DC-DC converter, so that be transported to the adjustment width basically identical (for example 8) of the pwm signal of each light-emitting diode group 30.The oscillogram of pwm signal that is transported to redness (R) light-emitting diode group 30 is shown in Figure 19 A, the oscillogram of pwm signal that is transported to green (G) light-emitting diode group 30 is shown in Figure 19 B, and the oscillogram of pwm signal that is transported to blueness (B) light-emitting diode group 30 is shown in Figure 19 C.
180 pairs of backlight drive control units are carried out PAM (pulse amplitude modulation) from the signal that for example DC-DC converter is transported to each light-emitting diode group 30, are transported to summit (peak) value of the constant current value ILED of each light-emitting diode group 30 with adjustment.Therefore, backlight drive control unit 180 is being carried out adjustment to the signal that is transported to each light-emitting diode group 30 on the time orientation and on the direction of summit value, guaranteeing the accuracy when adjusting, thereby make the balance of the adjustment accuracy of keeping each light-emitting diode group 30 become possibility.
Here, the actual example of the signal waveform when the signal that is transported to light-emitting diode group 30 is adjusted is as follows.Figure 20 A shows when at the signal on the time orientation modulated (PWM is performed) and the signal on the amplitude direction does not change (fixing), i.e. signal waveform under the unaltered situation of the peak current of LED element.In addition, Figure 20 C shows when fixing at the signal of time orientation (on the PWM direction) the only signal waveform under the modulated situation of the signal on the amplitude direction.In addition, Figure 20 B shows when modulated and also be modulated at signal waveform under the situation at the signal on the amplitude direction at the signal on the time orientation.
Note, for example can utilize white balance to wait to concentrate under the situation of adjusting briliancy, backlight drive control unit 180 is carried out modulation (PWM) on time orientation, and the modulation on the amplitude direction (PAM) can be performed, and proofreaies and correct luminous output with the Temperature Distribution of utilizing display.
When adjusting the light emission operation of the light-emitting diode group 30 that constitutes back light unit 2, on amplitude direction and time orientation, carry out adjustment according to the backlight drive control unit 180 that the invention among the application constitutes by this way, so that the adjustment resolution in all light-emitting diode group 30 of each color becomes consistent.
In addition, because the backlight drive control unit 180 according to the application's invention suitably detects the Temperature Distribution of extending towards the display bottom from display top, to carry out the adjustment on the amplitude direction based on testing result, thereby carry out peak value control, therefore can utilize the Temperature Distribution of display to eliminate the inhomogeneities of demonstration the current value that is transported to light-emitting diode group 30.
Note, with reference to the accompanying drawings and the preferred embodiments of the present invention that are described in detail the present invention has been described, but it should be understood by one skilled in the art that, the present invention is not limited to these embodiment, under the situation that does not break away from the scope and spirit of the present invention that propose by appended claims and limits, can realize various modifications, replacement structure or equivalent.
Claims
(according to the modification of the 19th of treaty)
1. (revise afterwards) a kind of drive unit that is used for back light unit, wherein a plurality of light-emitting diodes are disposed in different piece with a plurality of light-emitting diode groups that every trichromatic mode is connected in series in described back light unit,
Described drive unit comprises:
Signal generating apparatus is used to generate the luminous signal of described light-emitting diode group;
Drive unit is used for the signal that generated by described signal generating apparatus based on, drives described light-emitting diode group;
Voltage supply device is used for to described light-emitting diode group supply voltage;
The luminous quantity checkout gear is used to detect from the amount of the light of the light-emitting diode group emission that has been supplied voltage;
Temperature-detecting device is used to detect one or more temperature of described light-emitting diode group; And
Control device, be used for based on by the detected luminous quantity of described luminous quantity checkout gear with by the detected one or more temperature of described temperature-detecting device, at least control described signal generating apparatus, with control and the corresponding luminous output of each light-emitting diode group of having arranged.
2. (revise afterwards) drive unit as claimed in claim 1,
Wherein, described each light-emitting diode group is disposed in the wherein said a plurality of LED elements that are connected in series and has in the zone of essentially identical temperature.
3. (revise afterwards) drive unit as claimed in claim 2,
Wherein, described each light-emitting diode group fitted to be and makes the described a plurality of light-emitting diodes that are connected in series be arranged in the horizontal direction.
4. (revise afterwards) drive unit as claimed in claim 1,
Wherein, described signal generating apparatus generates pulse-width signal.
5. (revise afterwards) drive unit as claimed in claim 1,
Wherein, described luminous quantity checkout gear detects from the amount of the light of the light-emitting diode group emission of the light-emitting diode that comprises any primary colors.
6. (revise afterwards) drive unit as claimed in claim 1, comprising:
Amplitude adjustment means is used for being adjusted at the amplitude of the constant current value that flows in the described light-emitting diode group according to by the detected one or more temperature of described temperature-detecting device,
Wherein, described control device is controlled described amplitude adjustment means and connected described signal generating apparatus, to control the luminous output of described light-emitting diode group.
7. (revise afterwards) drive unit as claimed in claim 1, comprising:
Selector installation is used for selecting to constitute the light-emitting diode group of described back light unit according to by the detected one or more temperature of described temperature-detecting device,
Wherein, described control device is based on the signal that has been generated by described signal generating apparatus, the luminous quantity of the light-emitting diode group that control has been selected by described selector installation.
8. (revise afterwards) drive unit as claimed in claim 1, comprising:
Be used to store the memory of correction data, described correction data is used for proofreading and correct amount by the detected light from described light-emitting diode emission of described luminous quantity checkout gear accordingly with the part of having placed described light-emitting diode,
Wherein, described control device based on by be stored in the described memory the corrected luminous quantity of correction data and by the detected one or more temperature of described temperature-detecting device, control described signal generating apparatus.
9. (revise afterwards) drive unit as claimed in claim 1, comprising:
Memory table; In described memory table, stored the correcting value data that obtains by predetermined actual measurement method; So that under described luminous quantity checkout gear is disposed in situation away from the part of described light-emitting diode group; Described luminous quantity checkout gear will detect as the low light level from the light of described light-emitting diode group emission; And under described luminous quantity checkout gear is disposed in situation near the part of described light-emitting diode group; Described luminous quantity checkout gear will detect as high light from the light of described light-emitting diode group emission
Wherein, described control device is based on the correcting value data that is stored in the first memory table, proofread and correct by the detected luminous quantity of described luminous quantity checkout gear, with based on calibrated luminous quantity with controlled described signal generating apparatus by the detected one or more temperature of described temperature-detecting device.
10. (revise afterwards) drive unit as claimed in claim 1, comprising:
The light amount ratio adjusting device is used for suitably adjusting the light amount ratio of each light-emitting diode, and
The second memory table has wherein been stored when obtaining white light by described light amount ratio adjusting device with the temperature information of any one color for referencial use and the correcting value data by the actual measurement method acquisition be scheduled to,
Wherein, described control device is based on the correcting value data that is stored in the described second memory table, proofread and correct by the detected luminous quantity of described luminous amount detection device value, with based on calibrated luminous quantity with controlled described signal generating apparatus by the detected one or more temperature of described temperature-detecting device.
(11. revising the back) a kind of driving method that is used for back light unit, wherein a plurality of light-emitting diodes are disposed in different piece with a plurality of light-emitting diode groups that every trichromatic mode is connected in series in described back light unit,
Described driving method comprises:
Voltage supply step, this step is fed to each described light-emitting diode group with voltage;
Luminous quantity detects step, and this step detects from supplied the amount of light of the light-emitting diode group emission of voltage by described voltage supply step;
Temperature detection step, this step detect one or more temperature of described light-emitting diode group;
Signal generates step, and this step is based on being detected the detected luminous quantity of step and by the detected one or more temperature of described temperature detection step, generated the luminous signal of described light-emitting diode group by described luminous quantity; And
Controlled step, this step is based on generating the signal that step generates by described signal, control and the corresponding luminous output of corresponding a plurality of light-emitting diode groups of having arranged.
(12. revising the back) driving method as claimed in claim 11,
Wherein, described each light-emitting diode group is disposed in the wherein said a plurality of LED elements that are connected in series to be had in the zone of essentially identical temperature, and
At described each light-emitting diode group place, luminous output and described each light-emitting diode group be Be Controlled accordingly.
(13. revising the back) driving method as claimed in claim 11,
Wherein, described each light-emitting diode group fitted to be and makes the described a plurality of light-emitting diodes that are connected in series be arranged in the horizontal direction, and
At described controlled step place, luminous output and described each light-emitting diode group be Be Controlled accordingly.
(14. revising the back) driving method as claimed in claim 11,
Wherein, generate the step place at described signal, pulse-width signal is generated.
(15. revising the back) driving method as claimed in claim 11,
Wherein, detect the step place at described luminous quantity, the amount of the light that generates from the light-emitting diode group of the light-emitting diode that comprises any primary colors is detected.
16. (revising the back) driving method as claimed in claim 11 comprises:
The amplitude set-up procedure, this step is adjusted at the amplitude of the constant current value that flows in the described light-emitting diode group according to by the detected one or more temperature of described temperature detection step,
At described amplitude set-up procedure place,, control the luminous output of described light-emitting diode group like this based on the constant current value of having carried at described amplitude set-up procedure place with by the luminous signal of described signal generation step generation.
17. (increase) driving method as claimed in claim 11 comprises:
Select step, this step selects to constitute the light-emitting diode group of described back light unit according to by the detected one or more temperature of described temperature detection step,
Like this at described controlled step place, based on generating the signal that step generates by described signal, the luminous quantity of the light-emitting diode group that control has been selected by described selection step.
18. (increase) driving method as claimed in claim 11 comprises:
Aligning step, this step is proofreaied and correct the luminous quantity that is detected the detected described light-emitting diode of step by described luminous quantity accordingly with the part of having placed described light-emitting diode,
Generate the step place at described signal like this, by the corrected luminous quantity of described aligning step with by the detected one or more temperature of described temperature detection step, generate luminous signal based on.
19. (increase) driving method as claimed in claim 11 comprises:
First aligning step, this step is based on the correcting value data of the memory table of wherein having stored the correcting value data that obtains by predetermined actual measurement method, correction is from being used at the luminous quantity of described luminous detection step detection from the transducer acquisition of the amount of the light of described light-emitting diode group emission, make under described transducer is disposed in situation away from the part of described light-emitting diode group, described transducer will detect as the low light level from the light of described light-emitting diode group emission, and under described transducer is disposed in situation near the part of described light-emitting diode group, described transducer will detect as high light from the light of described light-emitting diode group emission
Wherein, generate the step place at described signal, by the luminous quantity of described first aligning step correction with by the detected one or more temperature of described temperature detection step, described luminous signal is generated based on.
20. (increase) driving method as claimed in claim 11 comprises:
The light amount ratio set-up procedure, this step is suitably adjusted the light amount ratio of the light-emitting diode of each color; And second aligning step, this step is proofreaied and correct by the detected luminous quantity of described luminous detection step based on memory table, stored in the described memory table when obtaining white light by described light amount ratio set-up procedure with the temperature information of any one color for referencial use and the correcting value data by predetermined actual measurement method acquisition
Wherein, generate the step place at described signal, by the luminous quantity of described second aligning step correction with by the detected one or more temperature of described temperature detection step, described luminous signal is generated based on.
Claims (16)
1. drive unit that is used to comprise the back light unit of light-emitting diode group, in described light-emitting diode group, a plurality of light-emitting diodes connect with every trichromatic mode cascade,
Described drive unit comprises:
Signal generating apparatus is used to generate the signal with any amplitude;
Adjusting device is used for the signal that generated by described signal generating apparatus based on, adjusts the luminous quantity of described light-emitting diode group;
Voltage supply device is used for to each described light-emitting diode group supply predetermined voltage;
The luminous quantity checkout gear, be used to detect according to by the voltage of described voltage supply device supply from the amount of the light of described light-emitting diode group emission;
Temperature-detecting device is used to detect one or more temperature of described light-emitting diode group; And
Control device is used for based on controlling described signal generating apparatus by the detected luminous quantity of described luminous quantity checkout gear with by the detected one or more temperature of described temperature-detecting device.
2. drive unit as claimed in claim 1,
Wherein, described signal generating apparatus generates pulse-width signal.
3. drive unit as claimed in claim 1,
Wherein, described luminous quantity checkout gear detects from the amount of the light of the light-emitting diode group emission of the light-emitting diode that comprises any primary colors.
4. drive unit as claimed in claim 1 also comprises:
Amplitude adjustment means is used for adjusting the amplitude of constant current value according to by the detected one or more temperature of described temperature-detecting device,
Wherein, described voltage supply device is used to allow the voltage of the supply of each light-emitting diode group to change based on the constant current value of having come from described adjusting device transmission.
5. drive unit as claimed in claim 1 also comprises:
Selector installation is used for selecting to constitute the light-emitting diode group of described back light unit according to by the detected one or more temperature of described temperature-detecting device,
Wherein, described adjusting device is used for the signal that generated by described signal generating apparatus based on, adjusts the luminous quantity of the light-emitting diode group of being selected by described selector installation.
6. drive unit as claimed in claim 1 also comprises:
The memory of storage correction data, described correction data are used for proofreading and correct amount by the detected light from described light-emitting diode emission of described luminous quantity checkout gear accordingly with the part of having placed described light-emitting diode,
Wherein, described control device based on by be stored in the described memory the corrected luminous quantity of correction data and by the detected one or more temperature of described temperature-detecting device, control described signal generating apparatus.
7. drive unit as claimed in claim 1 also comprises:
Memory table; In described memory table, stored the correcting value data that obtains by predetermined actual measurement method; So that under described luminescence detection apparatus is placed on situation away from the part of described light-emitting diode group; Described luminescence detection apparatus will detect as the low light level from the light of described light-emitting diode group emission; And under described luminescence detection apparatus is placed on situation near the part of described light-emitting diode group; Described luminescence detection apparatus will detect as high light from the light of described light-emitting diode group emission
Wherein, described control device is based on the correcting value data that is stored in the described memory table, proofread and correct by the detected luminous quantity of described luminous quantity checkout gear, with based on calibrated luminous quantity with controlled described signal generating apparatus by the detected one or more temperature of described temperature-detecting device.
8. drive unit as claimed in claim 1 also comprises:
Adjusting device and memory table, described adjusting device is used for suitably adjusting the light amount ratio of each light-emitting diode, stored in the described memory table when obtaining white light by described adjusting device with the temperature information of any one color for referencial use and the correcting value data by predetermined actual measurement method acquisition
Wherein, described control device is based on the correcting value data that is stored in the described memory table, proofread and correct by the detected luminous quantity of described luminous amount detection device value, with based on calibrated luminous quantity with controlled described signal generating apparatus by the detected one or more temperature of described temperature-detecting device.
9. driving method that is used to comprise the back light unit of light-emitting diode group, in described light-emitting diode group, a plurality of light-emitting diodes connect with every trichromatic mode cascade,
Described driving method comprises:
Voltage supply step, this step is fed to each described light-emitting diode group with predetermined voltage;
Luminous quantity detects step, this step detect according to by the voltage of described voltage supply step supply from the amount of the light of described light-emitting diode group emission;
Temperature detection step, this step detect one or more temperature of described light-emitting diode group;
Signal generates step, and this step by the detected luminous quantity of described luminous detection step with by the detected one or more temperature of described temperature detection step, generates the signal with any amplitude based on; And
Set-up procedure, this step is adjusted the luminous quantity of described light-emitting diode group based on generating the signal that step generates by described signal.
10. driving method as claimed in claim 9,
Wherein, described signal generation step is suitable for generating pulse-width signal.
11. driving method as claimed in claim 9,
Wherein, described luminous quantity detection step is suitable for detecting the light quantity of having launched from the light-emitting diode group that comprises the light-emitting diode with any primary colors.
12. driving method as claimed in claim 9 also comprises:
The amplitude set-up procedure, this step is adjusted the amplitude of constant current value according to by the detected one or more temperature of described temperature detection step,
Wherein, described voltage supply step is suitable for allowing the voltage of the supply of each light-emitting diode group to change based on the constant current value of having come in described set-up procedure transmission.
13. driving method as claimed in claim 9 also comprises:
Select step, this step selects to constitute the light-emitting diode group of described back light unit according to by the detected one or more temperature of described temperature detection step,
Wherein, described set-up procedure is suitable for based on generating the signal that step generates by described signal, adjusts the luminous quantity of the light-emitting diode group of being selected by described selection step.
14. driving method as claimed in claim 9 also comprises:
Aligning step, this step is proofreaied and correct the luminous quantity that is detected the detected described light-emitting diode of step by described light accordingly with the part of having placed described light-emitting diode,
Wherein, described signal generates step and is suitable for based on by the corrected luminous quantity of described aligning step with by the detected one or more temperature of described temperature detection step the signal that generation has any amplitude.
15. driving method as claimed in claim 9 also comprises:
Aligning step, this step is based on the correcting value data of the memory table of wherein having stored the correcting value data that obtains by predetermined actual measurement method, correction detects the luminous quantity that obtains from the transducer of the amount of the light of described light-emitting diode group emission from being used for detecting step at described luminous quantity, make under described transducer is placed on situation away from the part of described light-emitting diode group, described transducer will detect as the low light level from the light of described light-emitting diode group emission, and under described transducer is placed on situation near the part of described light-emitting diode group, described transducer will detect as high light from the light of described light-emitting diode group emission
Wherein, described signal generates step and is suitable for based on the luminous quantity of having been proofreaied and correct by described aligning step with by the detected one or more temperature of described temperature detection step the signal that generation has any amplitude.
16. driving method as claimed in claim 9 also comprises:
Set-up procedure, this step is suitably adjusted the light amount ratio of the light-emitting diode of each color; And aligning step, this step is proofreaied and correct based on the corrected value in the memory table and is detected the detected luminous quantity of step by described luminous quantity, stored in the described memory table when obtaining white light by described set-up procedure with the temperature information of any one color for referencial use and the correcting value data by the actual measurement method acquisition be scheduled to
Wherein, described signal generates step and is suitable for based on the luminous quantity of having been proofreaied and correct by described aligning step with by the detected one or more temperature of described temperature detection step the signal that generation has any amplitude.
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| JP2004205146 | 2004-07-12 | ||
| JP205146/2004 | 2004-07-12 | ||
| JP336373/2004 | 2004-11-19 |
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| CN1842923A true CN1842923A (en) | 2006-10-04 |
| CN100530706C CN100530706C (en) | 2009-08-19 |
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| WO2009129650A1 (en) * | 2008-04-22 | 2009-10-29 | 光远科技股份有限公司 | Attenuating compensation method for led backlight plate of lcd and liauid crystal display |
| CN102007815A (en) * | 2007-07-31 | 2011-04-06 | 克里公司 | Correction of temperature induced color drift in solid state lighting displays |
| CN102375461A (en) * | 2010-08-16 | 2012-03-14 | 上海航空电器有限公司 | Bus control-based digital light modulation technology of control panel of airplane driving cabin |
| CN102472906A (en) * | 2009-08-31 | 2012-05-23 | 夏普株式会社 | Driver device, backlight unit, and image display apparatus |
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