WO2009129650A1 - 液晶显示器led背光装置的衰减补偿方法和液晶显示器 - Google Patents

液晶显示器led背光装置的衰减补偿方法和液晶显示器 Download PDF

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Publication number
WO2009129650A1
WO2009129650A1 PCT/CN2008/000824 CN2008000824W WO2009129650A1 WO 2009129650 A1 WO2009129650 A1 WO 2009129650A1 CN 2008000824 W CN2008000824 W CN 2008000824W WO 2009129650 A1 WO2009129650 A1 WO 2009129650A1
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Prior art keywords
led
value
optical sensor
liquid crystal
crystal display
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PCT/CN2008/000824
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English (en)
French (fr)
Inventor
王遵义
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光远科技股份有限公司
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Priority to PCT/CN2008/000824 priority Critical patent/WO2009129650A1/zh
Publication of WO2009129650A1 publication Critical patent/WO2009129650A1/zh

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133621—Illuminating devices providing coloured light
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0666—Adjustment of display parameters for control of colour parameters, e.g. colour temperature
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/021—Power management, e.g. power saving
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2340/00—Aspects of display data processing
    • G09G2340/06—Colour space transformation
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/145—Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources

Definitions

  • the present invention relates to a display attenuation compensation method, and more particularly to an attenuation compensation method for an LED backlight panel display and the display. Background technique
  • the biggest advantage is that the light frequency is pure, so that the color gamut can cover about 130% of the NTSC standard, allowing viewers to feel richer colors. Variety.
  • the use of "dynamic backlight area control" in LCD-TV can increase the contrast ratio of LCD-TV to over 10,000:1, and even its low-brightness color gamut can be improved. To the level of high brightness, and also to reduce the dynamic image blur of the motion picture.
  • the in-plant photometric color measuring instruments are used to measure the LEDs or LEDs of each group.
  • the brightness and chromaticity of each color are calculated according to the brightness and chromaticity requirements of the backlight.
  • the Dot Correcting Value DCV of each LED is obtained, and these DCV values are stored and recorded.
  • the LEDs are used to weight the LEDs to display the same chromaticity and brightness when the LEDs on the backlight are lit. Therefore, these values are called "Standard Dot Correcting Value".
  • the biggest disadvantage of the direct-illumination backlight is that the light intensity is attenuated after long-term use of the LED, and if the three color-separated LEDs are used, the attenuation speeds are different, even if the LEDs of the same color are limited.
  • Different manufacturing conditions and ambient temperature, and different attenuation speeds resulting in uneven brightness and chromaticity of each area of a backlight board, deviating from the standard requirements and affecting the quality of LCD-TV; even using white LED as the light source, each LED dies have different attenuation speeds and still cause uneven brightness and chromaticity between regions.
  • the sensitivity of the human eye is quite high, and it is even more unbearable for the aging of such products.
  • one or several color-photometry sensors are used to measure the three "tri-stimulus values" of the red, green and blue of the entire backlight in the full-bright state. And using the magnitude of the three stimulus values, the weight ratio of the red, green, and blue lights of the entire backlight panel is adjusted, thereby controlling the overall illumination brightness and white balance of all the LEDs. To compensate for the aging decay, the total supply of power is increased by this measurement as a weighted reference to enhance the overall brightness and total chromaticity of the overall backlight.
  • Another object of the present invention is to provide an LED backlight display display attenuation compensation method for automatically detecting the attenuation degree of each group of LEDs and compensating them separately.
  • Still another object of the present invention is to provide an LED backlight display display attenuation compensation method for quickly detecting the degree of attenuation of each group of LEDs and compensating them separately.
  • Still another object of the present invention is to provide an LED backlight panel display that automatically detects the degree of attenuation of each group of LEDs and compensates them separately.
  • Still another object of the present invention is to provide an LED backlight panel display that quickly detects the degree of attenuation of each group of LEDs and compensates them separately.
  • the LED backlight panel liquid crystal display attenuation compensation method of the present invention wherein the display comprises a set of liquid crystal display modules; a set of LED backlight panels having a plurality of LED die sets; the display is further provided with at least one set of optical sensors; An energy supply device that supplies energy to the LED die group and outputs an adjustable power; a set of storage devices storing the sensed value of the optical sensor, the storage device is stored in the liquid crystal display module in a predetermined state, and the LED a sensed value of the optical sensor when the die set is illuminated one by one at at least one known power; and a set of processing devices that receive the optical sensor sensed value and control the power output of the powered device.
  • the method comprises the steps of: a) limiting the liquid crystal display module to the predetermined time at a predetermined time a state, and turning off the power supply of the LED die set; b) illuminating at least one of the LED die sets with at least one known power stored by the storage device; c) sensing the LED crystal by the optical sensor The sensing value of the particle group is compared with the pre-stored sensing value in the storage device; d) when the sensing value deviates from the pre-stored sensing value by a predetermined difference, the processing device drives the energy-providing device to change the supply The electrical energy of the LED die.
  • the invention not only effectively eliminates the interference of external light noise, but also quickly and accurately checks the attenuation degree of each group of LED dies one by one, thereby real-time compensation, ensuring that the luminous intensity and chromaticity of each area of the display are uniform as new.
  • FIG. 1 is a block diagram of a first preferred embodiment of the present invention
  • FIG. 2 is a schematic diagram of the LED die set and current pushing circuit of FIG. 1;
  • FIG. 3 is a schematic structural view of the backlight of FIG. 1;
  • Figure 4 is a circuit diagram of Figure 1;
  • Figure 5 is a timing diagram of electrical signals of a synchronous phase detection process
  • FIG. 6 is a flow chart of a display attenuation compensation method of the present invention.
  • Figure 7 is a circuit diagram of Figure 1, illustrating the attenuation compensation process
  • Figure 8 is a perspective view of a 42” LED backlight panel showing how the most corner LEDs are detected by optical sensors
  • FIG. 9 is a perspective view of a backlight panel according to a second preferred embodiment of the present invention.
  • Figure 10 is a block diagram showing the circuit of a second preferred embodiment of the present invention.
  • FIG. 11 is a perspective view of a backlight panel according to a third preferred embodiment of the present invention.
  • Figure 12 is a perspective view showing a portion of a structure of a backlight panel according to a fourth preferred embodiment of the present invention.
  • DSP Digital Signal Processor
  • VA Voltage Amplifier
  • A/D Analog/Digital Converter
  • PCS programmable current source
  • a first embodiment of the display of the present invention includes a set of backlights 1 having a plurality of LED die sets, and a set of liquid crystal display modules 2 shielded in front of the backlights.
  • a set of energizing means 4 for energizing the LED die set a set of examples are illustrated as processing means 5 comprising digital processor DSP 500, and a set of storage means 6.
  • the storage device includes a read only memory EEPROM 61, an EEPROM 62, and an EEPROM 63 for storing data such as the SDCV.
  • the power driving circuit 40 includes an analog switch (Analog Switch) AS 402, a constant current source Iso 400, and a pulse width modulation circuit PWM generator 404.
  • the PWM generator 404 is a PWM wave that generates different duty-cycle ratios depending on the data of the "Brightness Control Data BCD" value. Therefore, the average luminance of the LED group 10 will be determined by the constant current source Iso 400 and the duty cycle ratio.
  • the constant current source Iso 400 of each group of LEDs 10 will not change, and its brightness will be changed proportionally according to the BCD value.
  • the general BCD value is a set of multi-bit data. For example, 8 bits can provide 256-step brightness control, 10 bits can provide 1024-order brightness control, and 12 bits can provide 4096-order brightness control.
  • the brightness control data BCD is sent by the digital signal processor DSP, and the DSP will send different BCD values to illuminate each group of LEDs according to different functional requirements.
  • the LED luminous intensity is only about 60 ⁇ 70% of its maximum brightness, so that when the LED luminous intensity is attenuated in the future, the difference can be used to improve the brightness of the LED.
  • LEDs of three colors of red, green, and blue, respectively are arranged in a matrix (iXj) as a backlight source, and the backlight is formed by a direct illumination method. Irradiation.
  • the appearance of the backlight panel is roughly a six-sided hollow box-shaped structure, six sides are respectively labeled as front and rear planes 101, 103, left and right planes 104, 102, and upper and lower planes are 105, 106.
  • the other five faces 101, 102, 103, 104, 106 may be made of a material such as plastic or metal, and are all opaque faces, and a total reflection surface is disposed inside, except that the upper surface 105 is a light-emitting surface.
  • a diffusion sheet 12 is disposed on the upper surface 105 as a light-emitting surface to uniformly diffuse the light of the backlight directly to the LED under the regional illumination characteristics in which the respective LEDs are retained.
  • the diffusion sheet 12 is further provided with other panel structures 120.
  • a phototransistor 3 as an optical sensor is disposed at an appropriate position in the center of the lower plane 106, for example, to sense the brightness of the light from the LED die set 10.
  • the phototransistor 3 is connected in series with the load resistor as a current-voltage conversion, and then passed through a voltage amplifier (Voltage Amplifier) VA 52, which can be selected, for example, xl, ⁇ 10, ⁇ , A variety of different gains, such as voltage gain range control, to generate different ranges of photocurrents for LEDs of different distances.
  • VA 52 Voltage Amplifier
  • the gain selection is determined by the gain file GR sent by the DSP 50. Since the distance between each group of LEDs and the optical sensor is quite different, the voltage amplifier 52 requires different amplification gains to achieve a suitable voltage level that can be performed by the analog/digital converter (A/D converter) 54.
  • the digital signal output of the A/D converter 54 is sent to the DSP 50 for processing.
  • the backlight 1 is disposed behind the liquid crystal display module 2 (including a glass substrate, a liquid crystal, a color filter, a polarizing film, a TFT glass, etc.), when the optical sensor is used to detect the brightness of the LED in the display body, each group The brightness of the light emitted by the LED reflected back to the optical sensor will be affected by the following factors: (1) the reflection coefficient of each surface of the backlight; (2) the reflection coefficient of each optical surface structure in the liquid crystal display module; (3) The degree of opening/closing of the liquid crystal valve; (4) the amount of incident light of the ambient light and other factors.
  • the first two factors are the backlight panel and the panel structure. After the backlight panel and the liquid crystal display module are assembled, the influencing factors are completely fixed; the degree of opening/closing of the liquid crystal valve can be controlled by the liquid crystal valve in a specific state during the test, for example Make the panel appear completely dark, and you can confirm that the liquid crystal molecules are completely closed. Closed state. At this time, the reflected or diffused light of the LED to be tested will be fixed; and when the liquid crystal is fully closed, the incident light from the external environment is also largely shielded from entering the machine, and the influence of external ambient light on the optical sensor can be reduced. .
  • the present invention further proposes a "synchronous phase detection" process for processing the sensing value of the optical sensor with a DSP as shown in FIG. 5, similar to an analog lock-in amplifier function, fixing the BCD value sent by the DSP.
  • the synchronization phase is used to integrate the positive and negative phases (ie, positive phase addition, negative phase subtraction).
  • the BCD is a 10-bit data set to the PWM generator.
  • the BCD value sent by the DSP will be 512, so that the PWM generates a 50% High, 50% Low square wave to drive the LED to emit light.
  • the DSP can use this clock to process the plus and minus data processing of positive and negative phases.
  • the analog switch is ON, the LED can be illuminated, and the other 50% Low period, the analog switch is OFF, so that the LED does not emit light in the negative phase, and the LED light passes through the interior of the backlight and the panel.
  • the different structures are reflected back onto the phototransistor 3, and the photocurrent I s is generated in synchronism with the LED illumination.
  • the DSP accumulates the data from the A/D in the 50% half cycle 81, 83, 85... of the High, and subtracts the data from the A/D in the 50% half cycle 82, 84, 86... of the Low, thus synchronizing
  • the sensed value of the positive phase will be gradually strengthened, and the negative phase has no light, no value. Can be reduced; the more cycles the DSP handles, the larger the sensed value will accumulate.
  • ambient light is mostly ambient light that changes DC or slow
  • the signal measured by the optical sensor is also a DC or slow-changing signal.
  • the sensed value generated by the ambient light enters the DSP, and the half cycle of the 50% of the high 81, 83, 85... is added, and the half cycle of the 50% of the low cycle 82, 84, 86... is subtracted due to Ambient light is almost DC or slow. Therefore, regardless of the half period of High or Low, the photocurrent I n is almost equal. Therefore, after the DSP performs positive and negative phase addition and subtraction, the sensed values almost cancel each other out.
  • the processed data in the DSP only has the sensing value generated by the light of the LED, which greatly increases the ratio of the light sensing value of the LED to the ambient light sensing value, thereby almost completely eliminating the influence of ambient light. .
  • step 71 the display is first adjusted to a full dark condition, and each corresponding current in the power supply device pushes the circuit to output to each LED die group (ij) one by one, for example, with the same known power, in order.
  • each group of LEDs 10 in the backlight panel is illuminated; for convenience of explanation, this known power is hereinafter referred to as "standard lighting power".
  • the attenuation of each group of LEDs must be detected first.
  • the so-called attenuation amount is the standard luminance difference between the LED after use and the factory. Therefore, in step 72, the value sensed by the phototransistor 3 is processed by the digital signal processor (DSP) to perform the above-mentioned "synchronous phase detection” processing.
  • the measured value is measured before the LED die is not attenuated, so it is called “Standard Sensing Data"; and the sensed value and its corresponding voltage gain file GR(i,j) are recorded at the same time.
  • EEPROM 62 thus, a record of the relative optical power level of each group of LEDs (including different color lights) before leaving the factory is established, as the LED fading of the group is tested in the future. The basis for the determination of the amount of reduction and the adjustment of compensation.
  • the step of automatically performing the attenuation detection every time the display is turned on is selected.
  • step 74 the liquid crystal display device of the display is controlled to be fully off, and the monochromatic light source of each group of LEDs (ij) is illuminated one by one by using the above-mentioned "standard lighting power”.
  • step 74 the voltage gain of the photovoltage generated by the light is processed by the voltage gain file GR(ij) stored in the EEPROM corresponding to the position (ij), and the A/D conversion value of the photovoltage after the gain is used.
  • the sensing value of each color light is obtained. For the sake of distinction, it is called “currently sensing data, CSD (ij)".
  • step 75 the DSP finds the "standard sensing value SSD(ij)J and the "standard single point correction value SDCV" corresponding to the group LED, and uses the following relationship to find the following "new single point".
  • Correction value NDCV New Dot Correcting Value
  • the system has a signal-to-noise ratio (S/N) of 33 times, so when the difference between the NDCV and the previously stored value reaches a predetermined value, for example 3%, the new single-point correction value is facilitated in step 76.
  • S/N signal-to-noise ratio
  • the NDCV is stored in the EEPROM 63 as the brightness compensation correction data of the adjusted LEDs.
  • the backlight board When the panel is in normal use, the backlight board must illuminate each group of LEDs in the backlight panel according to the requirements of “dynamic area brightness control”.
  • the brightness of a group of LEDs should be sent to the DSP area brightness control data LACBD by the LCD module.
  • the value is determined, but each group of LEDs is subjected to the aforementioned correction, so the true brightness control value BCD of the group of LEDs in this example is the product of the LACBD value and the single point correction value DCV value, and in step 77, it is determined whether compensation is required.
  • step 78 If there is a significant change in brightness, it will be in step 78, as shown in Figure 7 by the DSP 50.
  • the required brightness value LACBD sent by the area brightness control is multiplied with the new single point correction value NDCVJ, and then some suitable high bits are taken as the "brightness control value BCD" of the LED, and sent to the PWM generator 404.
  • This increase corresponds to the duty cycle ratio of the PWM to increase the brightness of the set of LEDs 10, and restores the original standard to maintain the factory brightness and chromaticity.
  • each "group” LED is an LED that is illuminated by the same group of circuits, but in actual implementation, a single LED can also be used as a group. Or, a plurality of LEDs are driven together by a plurality of circuits in an adjacent small area to form a so-called "LED chip group” for common correction and compensation. In addition, since the luminous intensity of the LED sometimes rises and then drops, this compensation is not a periodic task ratio that enhances the driving signal.
  • the calibration and adjustment can be performed at any time, and is not limited to the time when the power is turned on, or can be performed every predetermined time such as one thousand hours, shutdown, or the user presses the button command calibration. Automatically detect compensation to achieve a new look and brightness of the entire display and backlight.
  • a 42-inch LED backlight LCD-TV is taken as an example.
  • the size of the backlight is shown in Figure 8.
  • the optical power of the photoreceptor is 0.5 X l (T 8 w can be seen that the incident amount of ambient light is about 6 times larger than the incident amount of the LED light.
  • the above description is for the LED that is farthest from the optical sensor. If one LED is only 4cm away from the optical sensor, the photocurrent generated by the LED to the phototransistor is about 4 ⁇ A according to the above calculation. The size is about 2000 times the photocurrent generated by the farthest LED, and the voltage amplifier (VA) gain of the latter stage must be reduced to xl times, otherwise the voltage will reach saturation.
  • VA voltage amplifier
  • the above "standard lighting power” can also select multiple. This different power is taken as the standard by the distance from the optical sensor. The lighting power in the near place is lower, and the lighting power in the far place is higher. It only needs to be the same as the lighting condition when the recording is established before leaving the factory.
  • the same diffusion sheet 12 front plane 101", right plane 102", left plane 104", upper plane 105", Other configurations 120", processing device 5", voltage amplifier (VA) 52", analog/digital converter (A/D) 54", storage device 6", read only memory (EEPROM) 62", circuit 40", etc.
  • VA voltage amplifier
  • A/D analog/digital converter
  • EEPROM read only memory
  • circuit 40 circuit 40
  • the LED can be used not only in a single-color LED, but also in a lower plane 106", which is provided with three LED crystals of different colors to be collectively packaged into a so-called “three-in-one” LED color LED 10", each of which The LEDs are a group, which constitutes a matrix of fixed pitch (iXj).
  • a plurality of optical sensors 3" are disposed, for example, on the rear plane 103", and the sensitized values of these optical sensors can be added together to be used as a single use, thereby increasing sensitivity-sensitivity.
  • the optical sensor 3" can be a wide-band spectral optical sensor of a photodiode or other materials in addition to the above-mentioned silicon (Si) phototransistor, as long as there is a light sensitivity in the visible light spectrum, and the sensitivity of each spectrum is inexhaustible. Equal; the optical sensor can also be separately covered with red, green, blue three-band filter chrominance light sensor.
  • each optical sensor 3" and each LED 10" are different, the reflection coefficient of the optical path Differently, the photo-response of each of the LEDs 10'' is different for the optical sensor 3''; however, as long as the position of the LED 10" and the reflection coefficient of the optical path are not changed with respect to the optical sensor 3", the illumination thereof The sensitivity will not change. Therefore, repeat the same "standard lighting power" to illuminate each corresponding LED 10". If the sensory value is changed after optical metering, the LED can still be clearly analyzed. The effect of attenuation is compensated.
  • the power supply to the LED is not controlled by the periodic task ratio of the pulse width modulation PWM, but the programmable current source PCS (Programmable Current Source) 406'' is used to adjust the brightness together with the duty cycle of the pulse width modulation. .
  • the current magnitude Iso of the programmable current source is controlled by the ratio of BCD sent by the DSP 50"; and different BCD values are sent depending on different operational functions. For example, when the panel is normally used, the BCD value will be from the EEPROM 63. The NDCV is obtained and sent an equal value; however, when the "standard lighting power" is used to detect the LED, the value of the BCD must be obtained from the SDCV in the EEPROM 61".
  • the duty cycle size of the PWM generator 404" is scaled by the data PWMD sent by the DSP 50.
  • its PWMD value is equivalent to the LACBD value sent by the "dynamic area brightness control”; but when the "standard bright spot power” is lit to light each LED for detection, the PWMD is fixed at 50%.
  • the PWM value of the task cycle is fixed.
  • each group of LEDs 10" has a corresponding set of constant current correction data.
  • the LEDs of each color have only the problem of brightness attenuation.
  • the amount of chromaticity change of the illuminating light can be neglected; but after actual long-term use, the LEDs of various colors are in brightness. Attenuation also causes some minor chromaticity changes.
  • the LED dies produce such a decay of the illuminating frequency distribution, if only the brightness of each monochromatic LED is adjusted to return to the factory standard, the deviation of the chromaticity cannot be compensated and restored, so the original color cannot be restored. Degree requirements.
  • a set of three chromatic optical sensors 31"', 32"', 33'" for red, green, and blue color measurement are respectively disposed on the rear plane 103"', and a plurality of measurement are set under Plane 106'"
  • the "three-in-one" LED group 10'" are composed of three standard color filters of red, green and blue respectively ( Color matched filter) formed by an optical sensor.
  • the frequency response of the chrominance optical sensors 31'", 32'", 33'" is not a narrow-frequency response that is only coincident with the illuminating frequency, even the chromaticity optical sensor 31'" that illuminates the red and blue with green light, 33'", there is still a lower photocurrent output.
  • each chromaticity optical sensor 31"', 32'", 33'" has different sensing values for each color light emitted by the LED group 10'", and by using these different sensing values, the decay of each color light can be known. To the extent that the driving values of the three different color lights of red, green and blue in the light-emitting diode group 10'" are mixed, the original brightness and chromaticity are restored.
  • the red, green and blue LEDs of each of the LED groups 10'" are first measured by the in-plant photometric color measuring instrument.
  • the three individual stimuli are denoted as 9 values such as X k , X 2r > X 3r and X lg , X 2g , X 3g and X lb , X 2b , X 3b , etc., where X k and X 2r are respectively
  • the three stimulus values of the group of red LEDs are analogous. Therefore, if there are N groups of LED groups 10'" in the backlight panel, the 9N stimulation values must be measured by an in-plant photometric colorimeter.
  • the liquid crystal state of the panel is controlled to be in a dark state, and the light crystal grains of each color in the LED group 10'" are illuminated one by one by using the aforementioned "standard lighting power", and each color is recorded.
  • the sensing values of the optical sensors 31"', 32'", 33' for example, when lighting the red LED dies in the group, the three sensing values are recorded as x ⁇ , x 2r , x 3r , illuminate
  • x lg , x 2g , x 3g and blue LED dies are denoted as x lb , x 2b , x 3b , etc.;
  • the measured value is "standard sensed value”.
  • These 9N "standard sense values” have a linear relationship with the aforementioned 9N stimulus values. That is, the stimulus value of each color of each LED has a certain weighted proportional relationship with its sensed value.
  • X ir represents the red component
  • X ig represents the green component
  • X ib represents the blue component.
  • the color of each group of LEDs is known to be the total composition of X, X 2 , and X 3 , it can represent the group. Brightness and chromaticity. At this point, define
  • X20 X2r+X2g+X2b
  • the three stimulus values of X 1() , X 2 o, and X 3G can represent the brightness and chromaticity of the set of LEDs.
  • the backlight is used to generate brightness and chrominance decay of the LED, if the decayed group of LEDs can change the driving weight of each color light to emit a combination of different brightness, the three stimulation values of the group are restored, ie It can restore its brightness and chromaticity.
  • P G, P B three weights relative value proportional to the driving time of the original factory DCV to promote light emission, it will be the respective stimulus values scaled to P r X ir ', P g X ig ', l, 2, 3)o
  • the new relative driving weights of the respective colors of the set of LEDs can be calculated using equations (9), (10), and (11) , P g , P b to drive the brightness of each color of the set of LED lights. In this way, the three stimulation values after the mixing of the three color lights will return to the three stimulation values at the factory, so that the The group LEDs are restored to the factory standard brightness and chromaticity.
  • the sensitivity of the photosensitivity is smaller than that of the previous embodiments, and generally only 20 ⁇ 30
  • the signal/noise ratio of the sensed value is reduced by about %. Therefore, in the measurement of the sensed value, the signal can be "synchronized” by the digital signal processor by using the "synchronous phase detection method" described above. To increase its signal/noise ratio. Another way to increase the signal/noise ratio is to increase the so-called "standard lighting power" value for the "standard sensing value” measurement and the "current sensing value” measurement, using the larger "standard point". The Bright Power value compensates for its small sensitivity.
  • the driving current of a general low-power LED is generally "standard lighting power”
  • the driving current is 20 mA
  • the duty cycle of the PWM is 50%.
  • the "standard point” can be improved.
  • "Bright power” is a higher “standard lighting power” with a driving current of 50 mA and a PWM duty cycle of 50%. Therefore, when measuring "standard sensing value” and "current sensing value”, the signal/noise ratio will be improve.
  • the LED 10"" is disposed on the side of the backlight panel module, and is sent via the light guide panel 14'"'.
  • Light source steering, diffused light source design as long as its LED10"" can be separately illuminated, it can also pass
  • the attenuation is compensated; and in order to improve the signal/noise ratio, a design that increases the light sensing area may be adopted, for example, solar cells are cut to fit the space inside the backlight, respectively.
  • the front, rear, left, and right planes 101 ⁇ ", 103"", 104 ⁇ ", 102' ⁇ ' are used as light sensors to achieve the same attenuation compensation effect.
  • the illuminating intensity of each group of LEDs is corrected, and the aging attenuation of the LED is performed in real time before the user has not noticed, timely and quickly sensing in the body and calculating through the processing device.
  • the compensation ensures that the luminous intensity and chromaticity of the LEDs in each small area are completely compensated to the state as in the case of a new product, and therefore all of the above objects of the present invention can be effectively achieved by the present invention.

Description

液晶显示器 LED背光装置的衰减补偿方法和液晶显示器
技术领域
本发明涉及一种显示器衰减补偿方法，特别是涉及一种 LED背光板显示 器的衰减补偿方法及该显示器。 背景技术
利用红、 绿、 蓝三色的 LED作为背光板的光源， 最大优点在于发光频 率较纯， 使其色域 (color gamut)可涵盖到 NTSC标准的 130%左右， 让观看 者感受更丰富的色彩变化。 近年来， 由于 LCD-TV中利用 「动态背光区域 控制」 （dynamic backlight area control)可以使得 LCD-TV 的明暗对比度 (contrast ratio)提高到 10000: 1以上， 甚至其低亮度的色域也可以提高到高 亮度下的水平， 而且还可以减小动态影像的模糊感问题 (dynamic image blur)。
此外， 利用三色光时序驱动发亮而免除使用彩色滤色片之 color-filterless LCD-TV, 使得以红、 绿、 蓝三色光 LED为光源的直照式可 区域控制背光板也将日益普遍。 当然， 不仅可以采用三种色彩独立的 LED 作为光源， 也可以采用所谓 「三合一」 三色一体的 LED作为光源， 其色彩 及亮度均匀性更佳， 且价格较便宜， 市场接受度将日渐提升。
由于各 LED的发光效率均不相同，为能在出厂时得到共同的均匀亮度， 各 LED安置在背光板后， 会利用厂内测光测色仪器， 分别量测各颗 LED 或各组 LED的各色光亮度及色度， 并按背光板的亮度及色度需求计算， 得 到各 LED的单点校正值 (Dot Correcting Value)DCV,储存记录这些 DCV值， 并用以加权驱动各 LED, 可使背光板上的各 LED点亮时， 呈现出相同的色 度及亮度。所以这些值称为「标准单点校正值 SDCV(Standard Dot Correcting Value)] o
然而， 直照式背光板的最大缺点在于 LED经过长期使用后， 光强度会 衰减， 并且若采三种色彩分离的 LED, 其分别衰减的速度又不相同， 即使 同一色彩的 LED, 也受限于制造条件及环境温度的差异， 而具有不同的衰 减速度， 导致一片背光板的各区域亮度与色度不均匀， 偏离标准要求而影 响 LCD-TV的质量； 即使是利用白光 LED作为光源， 各 LED晶粒的衰减 速度不同， 仍会导致区域间亮度与色度不均的问题。 尤其人眼的敏感度相 当高， 更无法忍受此种产品老化现象。
在以往的技术中， 会利用一个或数个色度光传感器 (color-photometry sensor)测量整个背光板在全亮状态下的红、绿、蓝三个「刺激值」 (tri-stimulus value), 并利用此三个刺激值的大小， 调整整个背光板的红、 绿、 蓝三色光 的权值比例， 从而控制搭配出所有 LED的整体发光亮度及白平衡。 若要补 偿老化衰减现象时， 将以此测量值为基准加权计算而提高总供应电能， 以 增强整体背光板的总亮度及总色度。
利用此方法， 虽可以恢复整个背光板的平均总亮度及总色度， 但是却 无法对每个 LED的衰减进行一对一地调整补偿， 所以对各小区域的亮度及 色度因每个 LED老化所产生的差异， 及 「动态背光区域控制」 过程中所造 成亮度及色度的区域不均匀性， 毫无修补效果， 仍然不能完全补偿改善面 板的显示质量劣化问题。
因此， 若能提供一种可自动化、 有效率且分别检验各组 LED的衰减程 度， 分别加以补偿的方法及装置， 无疑地可保持具有 LED背光板显示器的 成像质量， 使其在使用寿命终结前， 维持全新时的发光亮度与均匀度， 而 成为最佳的解决方案。
发明内容
因此， 本发明的一个目的， 在于提供一种精确检测各组 LED衰减程度 并分别加以补偿的 LED背光板显示器衰减补偿方法。
本发明另一目的， 在于提供一种自动化检测各组 LED衰减程度并分别 加以补偿的 LED背光板显示器衰减补偿方法。
本发明的再一目的， 在于提供一种迅速检测各组 LED衰减程度并分别 加以补偿的 LED背光板显示器衰减补偿方法。
本发明的又一目的， 在于提供一种能精确检测各组 LED衰减程度并分 别加以补偿之具有 LED背光板显示器。
本发明的又另一目的， 在于提供一种自动化检测各组 LED衰减程度并 分别加以补偿的 LED背光板显示器。
本发明的又再一目的， 在于提供一种迅速检测各组 LED衰减程度并分 别加以补偿的 LED背光板显示器。
因此本发明的 LED背光板液晶显示器衰减补偿方法， 其中该显示器包 括一组液晶显示模块；一组具有多个 LED晶粒组的 LED背光板；该显示器 还设置有至少一组光学传感器； 一组向该 LED晶粒组供能且输出电能可调 的供能装置； 一组储存有该光学传感器感测值的储存装置， 该储存装置储 存有在液晶显示模块处于一个预定状态、 且和该 LED晶粒组在至少一个已 知功率下逐一点亮时的该光学传感器的感测值； 及一组接收该光学传感器 感测值并控制该供能装置输出电能的处理装置。
该方法包括下列步骤： a)在一个预定时间限制该液晶显示模块为该预定 状态， 且关闭该 LED晶粒组的电能供应； b)以该储存装置储存的至少一个 已知功率点亮该 LED晶粒组中的至少一组； c)将该光学传感器感测该 LED 晶粒组的感测值与该储存装置中预储存感测值对比; d)当该感测值偏离该预 存感测值达一个预定差值时， 由该处理装置驱动该供能装置变化供应该 LED晶粒的电能。 通过本发明， 不仅有效排除外部光噪声的干扰， 迅速且精确地逐个检 验各组 LED晶粒的衰减程度， 从而实时补偿， 确保显示器的各区域发光强 度与色度均匀如新。
附图说明
图 1是本发明第一较佳实施例的方块图； 图 2是图 1的 LED晶粒组与电流推动电路示意图；
图 3是图 1的背光板结构示意图；
图 4是图 1的电路示意图；
图 5是同步相位检测流程的电信号时序图；
图 6是本发明显示器衰减补偿方法的流程图；
图 7是图 1的电路示意图， 说明衰减补偿过程；
图 8是 42吋 LED背光板的立体示意图， 说明最角落的 LED如何被光 学传感器检测；
图 9是本发明第二较佳实施例的背光板立体示意图；
图 10是本发明第二较佳实施例的电路方块示意图；
图 11是本发明第三较佳实施例的背光板立体示意图；
图 12是本发明第四较佳实施例的背光板部份结构立体示意图。
附图中， 各标号所代表组件列表如下 1...背光板 2...液晶显示模块 3、 3'、 3"...光敏晶体管
4…供能装置 5、 5"…处理装置 6、 6"…储存装置
61~63、 61〃~63〃...只读存储器(£5?1 0]^)
10、 10'、 10"..丄 ED晶粒组 12、 12"...扩散片
40、 40"…电路 50、 50"...数字信号处理器 (DSP)
52、 52〃…电压放大器 (VA) 54、 54〃…模拟 /数字转换器 (A/D) 71~79...步骤 101、 101"、 10""...前平面
102、 102"、 102'"'...右平面 103、 103"、 103'"、 103""...后平面 104、 104"、 104〃"...左平面 105、 105〃...上平面
106、 106'、 106"、 106'〃...下平面 120、 120' '…其它构造
402...模拟开关 (AS) 400...恒流源 Iso
404、 404"…电路 PWM产生器 406"...可编程电流源 (PCS) 10"'、 10""…发光二极管 3""…太阳能电池 14'"'...导光板 31"'、 32"'、 33'"…光学传感器 电阻 具体实施方式
有关本发明的前述及其它技术内容、 特点与功效， 在以下配合参考图 的较佳实施例的详细说明中， 将可清楚的呈现。
针对上述问题， 本发明显示器的第一实施例如图 1 所示， 包括一组具 有多个 LED晶粒组的背光板 1、 一组遮蔽于该背光板前方的液晶显示模块 2、 一组例释为光敏晶体管 3的光学传感器， 一组向该 LED晶粒组供能的 供能装置 4、一组例释为包括数字处理器 DSP 500的处理装置 5、及一组储 存装置 6。 储存装置在本实施例中， 包括用以储存该 SDCV等资料的只读 存储器 EEPROM 61、 EEPROM 62与 EEPROM 63。 本实施例中， 如图 2所示， 以例如两颗所发光均为红色的单色 LED晶 粒串接作为一组 LED 晶粒组 10， 并被单一组电流推动电路 (LED current driver)40供能而点亮， 电流推动电路 40包括模拟开关 (Analog Switch)AS 402、 恒流源 Iso 400及脉宽调变 (Pulse Width Modulation)电路 PWM产生器 404。 PWM 产生器 404 是依输入 「亮度控制数据 (Brightness Control Data)BCD」 值的数据而产生不同任务周期比 (duty -cycle ratio)的 PWM波。 所以 LED组 10平均发光亮度将由恒流源 Iso 400及任务周期比例共同决定。
在本实施例中，各组 LED 10的恒流源 Iso 400将不变，其亮度将视 BCD 值而等比例改变。一般 BCD值为一组多位数据， 例如 8位可提供 256阶的 亮度控制， 10位可提供 1024阶的亮度控制， 12位可以提供 4096阶的亮度 控制。 而此亮度控制数据 BCD是由数字信号处理器 DSP所送出， DSP将 视不同的功能需求， 送出不同的 BCD值来点亮各组 LED。 一般在出厂时， LED发光强度仅约为其最大亮度的 60~70%， 以便当日后 LED发光强度衰 减时， 即可利用此差值达到提高 LED亮度的目的。
如图 3所示， 本实施例中是利用多组发光分别为红、 绿、 蓝三种颜色 的 LED排列成矩阵 (iXj)，作为背光板光源， 并以直照式的方法形成背光板 的照射。 背光板外观大致呈一个六面中空箱形结构， 六面分别被标示为前、 后平面 101、 103, 左、 右平面 104、 102, 上、 下平面则为 105、 106。 其中 除上平面 105为出光面而可透光外， 其余五个面 101、 102、 103、 104、 106 可用塑料或金属等材料构成， 均为不透光面， 且其内部安置有全反射面或 全反射膜； 以将 LED晶粒组 10输出、 且未由出光面射出的光线经由面板 各处再反射至上平面 105， 以增加背光板输出光的效率。 作为出光面的上平面 105上则置有扩散片 12，以将背光板直照 LED的 光线在保留有各个 LED的区域性照射特性下， 稍加扩散均匀化。 本实施例 中， 扩散片 12上更设置有及其它面板构造 120。 且在例如下平面 106中央 的适当位置上设置有一个作为光学传感器 (optical sensor)的光敏晶体管 3， 以感测来自 LED晶粒组 10的光亮度。
如图 4所示，光敏晶体管 3反向串接负载电阻 ，作为电流电压转换， 再经一个可调整电压增益的电压放大器 (Voltage Amplifier)VA 52, 该电压放 大器可选择例如 xl， χ10， χΙΟΟ, ΙΟΟΟ等 4个增益档 (voltage gain range control)的多档不同增益， 以对应各种不同距离的 LED所产生不同范围的光 电流。 增益的选择是由 DSP 50所送出之增益档 GR而定。 由于各组 LED 与光学传感器距离相差很多， 因此电压放大器 52需要不同的放大增益来达 到可被模拟 /数字转换器 (A/D converter)54 执行的合适电压大小。 A/D converter 54的数字信号输出即送入 DSP 50内处理。
因为背光板 1是被装置在液晶显示模块 2(包括玻璃基板、 液晶、 彩色 滤光片、 偏光膜、 TFT玻璃等)背后， 在显示器机体内利用该光学传感器检 测 LED的光亮度时， 各组 LED所发出光反射回到光学传感器的亮度大小， 将受下列各因素影响： （1)背光板的各个面的反射系数； （2)液晶显示模块内 的各光学面结构反射系数； （3)液晶阀的开 /闭程度； （4)外界环境光线的入射 量大小等因素。
前两个因素是背光板及面板结构， 在背光板及液晶显示模块组装完成 后， 影响因素已完全固定； 液晶阀的开 /闭程度则可通过在测试时控制液晶 阀处于一个特定状态， 例如令面板呈现全暗， 即可确定液晶分子在完全关 闭状态。此时被测 LED的反射或漫射光将会固定；且液晶在全关闭状态下， 从外界环境的入射光线也被大量屏蔽而不能进入机内， 同时可减小外界环 境光线对光学传感器的影响。
上述第 4个因素， 一方面因每组 LED本身的光功率并不大， 而且只有 其中非常小部份反射光线或漫射光线会被光学传感器检测到； 相反地， 虽 然可控制液晶阀于全关闭状态， 但因外界光线可能非常强， 部份漏光即可 影响光学传感器而形成背景光的干扰， 影响检测的精确度。
因此， 本发明进一步提出如图 5所示， 用 DSP处理光学传感器感测值 的 「同步相位检测」 流程， 类似一个模拟锁相放大器 (lock-in amplifier)的功 能， 将 DSP送出的 BCD值固定在脉宽调变任务周期为 50%的值， 利用同 步相位进行正负相位的积分 (即正相位做加法，负相位做减法)，例如该 BCD 是以 10位之数据组输至 PWM产生器， 当 BCD=1023时为 100%的任务周 期，此时 DSP所送出去 BCD值将为 512， 使 PWM产生一个 50%High、 50 %Low的方波， 以驱动 LED发光。 - 因为 PWM产生器的时钟信号 clock是由 DSP所送出， DSP可利用此 clock的同步处理正、 负相位的加、 减数据处理。 脉冲为 High时， 模拟开 关为 ON, 供能使 LED发光， 而另外 50%Low的周期， 模拟开关为 OFF, 使 LED在负相位时不发光， LED的光线经背光板内部四周及面板内各不同 结构反射回到光敏晶体管 3上,其光电流 Is的产生恰与 LED是否发光同步。
DSP在 High的 50%的半周期 81、 83、 85…累加来自 A/D的数据，而在 Low 的 50%的半周期 82、 84、 86…减去来自 A/D的数据， 因而在同步相位的正 负相位加减过程中， 正相位的感测值将逐渐被加强， 负相位没有光， 无值 可减； DSP所处理累加的周期愈多， 该感测值累加将愈大。
相反地， 一般外界光线大都为直流或慢速改变的环境光线， 由光学传 感器量得的信号亦为直流或慢速改变的信号。 此环境光所产生的感测值进 入 DSP内， High的 50%之半周期 81、 83、 85...相加， Low的 50%之半周 期 82、 84、 86...相减， 由于环境光几乎为直流或慢速变化， 因此不管 High 或 Low的半周期，其光电流 In几乎相等，因而 DSP做正、负相位的加减后， 其感测值几乎互相抵消。利用以上方法， DSP内所处理后的数据只剩下 LED 的光所产生的感测值,大幅提高 LED的光感测值对环境光线感测值的比例， 由此几乎完全消除环境光线的影响。
由于背光板中各 LED晶粒组 10对光敏晶体管 3的几何位置及光学反 射路径均不随时改变， 一并参考附图 4及附图 6所示， 在背光板调校完成、 显示器完成全机组装后的步骤 71时， 是先将显示器调整至全暗条件下， 由 供能装置中的各对应电流推动电路， 以例如一个相同已知功率逐一输出给 各 LED晶粒组 (ij)， 循序点亮背光板内各组 LED 10; 为便于说明起见， 以 下将此已知功率称为 「标准点亮功率」。
为使日后能对 LED晶粒组 10的衰减补偿调回，必须先检测出各组 LED 的衰减量。 所谓衰减量就是 LED使用后与出厂前的标准亮度差， 所以随后 于步骤 72,利用数字信号处理器 (DSP)对该光敏晶体管 3感测的值进行上述 「同步相位检测」 处理， 因为此感测值是在 LED晶粒未衰减前测得， 所以 称 「标准感测值 SSD(Standard Sensing Data)」； 并同时将此感测值及其对应 的电压增益文件 GR(i，j)记录于 EEPROM 62中。 由此， 建立每一组 LED (包 含不同的色光)出厂前的相对光功率大小的记录，作为日后测试该组 LED衰 减量大小的判断及补偿调整的基础。
本实施例中， 是选择该显示器每次开机时， 自动进行衰减检测之步骤
73 , 此时会将显示器的液晶显示装置控制在全关闭状态， 利用上述的 「标 准点亮功率」 逐一点亮各组 LED(ij)的单色光源。 并于步骤 74利用储存于 EEPROM中、对应该位置 (ij)的电压增益文件 GR(ij)处理该光所产生光电压 的电压增益，并利用该增益后的光电压的 A/D转换数值，重新经过 DSP「同 步相位检测」 处理， 得到各色光的感测值， 为便于区别， 称之为 「现时感 测值 (currently sensing data), CSD(ij)」。
DSP在步骤 75 自储存装置中， 找出对应该组 LED 的 「标准感测值 SSD(ij)J及「标准单点校正值 SDCV」， 并利用下列关系式， 求出下列「新 的单点校正值 NDCV(New Dot Correcting Value)]：
NDCV=SDCV X SSD/CSD (1)
本实施例中假定系统的讯杂比 (S/N)达 33倍， 所以当 NDCV与原先储 存的数值差值达到一预定数值， 例如 3%时， 便于步骤 76将这些新的单点 校正值 NDCV存入 EEPROM 63中，做为调整后的各 LED的亮度补偿校正 数据。
当在面板正常使用时， 背光板必须按照 「动态区域亮度控制」 的需求 来点亮背光板内的各组 LED，某一组 LED的光亮度应由 LCD模块送入 DSP 的区域亮度控制数据 LACBD值决定， 但每组 LED均经过前述校正， 所以 本例中该组 LED的真正亮度控制值 BCD是由 LACBD值及单点校正值 DCV 值的乘积， 在步骤 77决定是否需补偿。
若发现亮度有明显变化，将于步骤 78， 由 DSP 50如图 7所示将「动态 区域亮度控制」所送入的需求亮度值 LACBD与 「新的单点校正值 NDCVJ 做乘法运算， 然后取合适的某些高位作为 LED的 「亮度控制值 BCD」， 送 到 PWM产生器 404,由此调高对应 PWM的任务周期比以增加该组 LED 10 的光亮度， 而恢复原先的标准， 使其保持出厂时的亮度与色度。
当然， 熟悉本技术领域者能轻易理解， 前述实施例中是例释每 「组」 LED为多颗由同一组电路致能点亮的 LED, 但实际实施时， 也可由单一颗 LED作为一组、或以一个相邻小区域内的多个电路共同驱动多个 LED构成 所谓 「LED晶粒组」， 共同校正及补偿。 此外， 由于 LED发光强度有时会 先升后降， 所以此补偿并非一味提升驱动信号的周期任务比。 且由于此感 测补偿程序全部在机体内进行， 可以随时进行校正及调整， 并不局限于开 机时， 也可在每操作例如一千小时、 关机、 或使用者以按钮指令校准等预 定时间进行自动检测补偿， 以达到整个显示器及背光板亮度与色度永远如 新的感觉。
此处以一个 42吋的 LED背光板 LCD-TV为例， 其背光板尺寸如图 8 所示，其中 Si光电二极管 3'置于背光板的中央位置，如果 LED10'为最边远 的一颗，光电二极管 3'的光受面积 a=1.0 cm2,其光感度 (photo -responsitivity) 在蓝光时 RS=0.4A/W， LED10'为一般低功率 LED, 在 Iso=20mA时， 其蓝 色光功率 mw， 则 LED10'发光时， 该光电二极管 3'所产生的光电流可 由下列步骤计算出：
(1) LED10'经上平面 105'、扩散膜、或面板各部份所反射回来的比例 设为 30%，其中 20%由扩散膜反射 (80/20的透射 /反射比)， 另 10%为面板 结构所反射。 (2) 因此该 LED10'所发出的光功率 P!=5mw中有 1.5mw被反射回 来。
(3) 假设该反射回来的 P尸 1.5mw光功率将以漫射方式平均分配到整 个下平面 106'， 总立体角为 2π。
(4)光电二极管 3'的接受面积 a=1.0cm2， 其所含的立体角 ΔΩ = ， 其中
Figure imgf000013_0001
3
cos^ =— = 0.055
55
ΔΩ≡ 2xl(T5 (5) 因 此 该 光 敏 晶 体 管 3' 所 接 受 到 的 光 功 率
P, =Prx^ = 5xlO-9W
(6) 光电二极管3'产生的光电流= ？^=0.4^\\^5.(^10^^=2.0 10"9A=2nA
(7) 该电路的噪声有两个主要来源， 其一为负载电阻 的热噪声 (thermal noise)电流 In， 其大小为 Ιη 2=41ίΤ/¾ Δ f， 其中 k为波兹曼常数， T 为背光板的温度， Af为频宽。若 PWM频率为 fw=30KHz，则要求 Af^3fw, 取
Figure imgf000013_0002
则热噪声电流 In=0.14nA， 因此原始的光电流 /噪声的比值 (S/N)=2/0.14=14倍。
(8) 将此光电流加噪声的信号输入放大器， A/D转换后进入 DSP并进 行「同步相位检测」 处理， 当要求每组 LED需在 lms内处理完， 即使背光 板中有一千组 LED晶粒组， 亦可在一秒钟内完成检测。 因此， DSP对此信 号的积分时间需限制在 lms内， 而相较于 PWM频率为 30KHz的光电流信 号， DSP可在 1ms内累加 30次感测值，使 S/N比至少同步提升 5.5倍。 亦即， 经 DSP「同步相位检测」处理后的 S/N比可达 77倍左右。 使所得的 LED感测值可以非常精确判断其衰减量， 其精度可达约 1.3 %。
(9) 如前 (7)项所述， 另一噪声来源为外界环境光线的干扰， 严重程度视 外界环境光而不同。假设外界环境光照度为 1000 lux, 即 1000 1m/m2， 相当 于 1.5W/m2的光功率照度，一般 LCD面板在液晶阀全开时，约有 10%的光 可透射到背光板内，而如果在液晶阀全闭时， 约只有全开的 1/500以下。所 以若要求在测试 LED时， 将液晶阀全关闭， 则在此情况下， 该环境光透射 到背光板内的光功率照度约为 0.3mw/m2， 这个光照度在光敏晶体管 3'的面 积 a=lcm2接受面上的入射光功率 P ambient)
Figure imgf000014_0001
相比前式算出 的 LED光线在此光感受器光功率 =0.5 X l(T8w可看出， 环境光的入射量比 LED光的入射量约大 6倍。 同样地， 由于环境光可以视为几乎直流或变化 很慢 (一般在 60Hz以内)， 所以如前所述， 经 DSP做正、 负相位的加减 30 次后， 其感测值将下降 30倍以上， 而 LED的感测信号由于同步的关系， 将会增加 30倍， 因此 LED的光功率产生的感测值与环境光的感测值之比 将提升到 30/(6/30) =900/6=150倍左右。所以可非常精确地判断出 LED的衰 减量， 其精确度可达 0.6%左右。
以上说明， 是针对离开光学传感器最远的一颗 LED, 若某一颗 LED离 光学传感器只有 4cm， 则按上述计算， 该 LED的光照到光敏晶体管所产生 的光电流大小约为 4 μ A， 其大小约为最远 LED所产生光电流的 2000倍， 后级的电压放大器 (VA)增益必需降为 xl倍， 否则电压会达到饱和。 当然， 本领域普通技术人员能轻易理解， 上述 「标准点亮功率」 亦可选择多个彼 此相异的功率， 以其与光学传感器之距离远近作为标准， 近处的点亮功率 较低， 远处点亮功率较高； 仅需与出厂前建立记录时点亮条件相同即可。
此外， 如图 9及图 10本发明第二较佳实施例所示， 与前实施例相同的 扩散片 12"、前平面 101"、右平面 102"、左平面 104"、 上平面 105"、 其它 构造 120"、处理装置 5"、 电压放大器 (VA)52"、模拟 /数字转换器 (A/D)54"、 储存装置 6"、只读存储器 (EEPROM)62"、电路 40"等不再赘述。其中， LED 不仅可采用单色发光 LED, 也可选择在下平面 106"上设置多颗由三种不同 颜色的 LED晶粒共同封装成一颗所谓「三合一」 的 LED彩色 LED10", 以 每颗 LED为一组，构成固定间距的矩阵 (iXj)排列。 由于背光板内含有多只 的矩阵排列 (iXj)LEDlO", 其数量 N=iXj， 因此共需要 3N组 「标准单点校 正值」 SDCV, 此数据必须存放在某一个只读存储器 EEPROM 61"中。
在本实施例中， 多个光学传感器 3"被设置在例如后平面 103"上， 这些 光学传感器的感光值可以加总在一起而视为单颗使用， 从而增加感光灵敏 (sensing-sensitivity)。此光学传感器 3"除上述的硅 (Si)光敏晶体管亦可为光电 二极管、 或其它材料的宽带谱光学传感器， 只要在可见光频谱都有光感度 (responsitivity)即可， 各频谱的感度则可不尽相等； 光学传感器也可选分别 覆盖有红、 绿、 蓝三波段滤光片组成的色度光传感器。 即使各光学传感器 3"与各 LED 10"的距离及方位均不同， 光学路径的反射系数也不同， 使各 LED 10〃对光学传感器 3' '的照光感度 (photo-response)均不同； 但只要 LED 10"的位置及光学路径的反射系数，相对于光学传感器 3"没有改变，其照光 感度就不会有变化。因此重复以同一个「标准点亮功率」来点亮各对应 LED 10"，如果经光学传感器测光后发现其感测值有变化，仍可清楚分析该 LED 衰减的效应而加以补偿。
本实施例中， 向 LED供能并非利用脉冲宽度调变 PWM的周期任务比 调控， 而是利用可编程电流源 PCS (Programmable Current Source)406' '与脉 宽调变的任务周期比共同调控亮度。 该可编程电流源的电流大小 Iso是由 DSP 50"所送出的 BCD比例调控其大小； 并视不同的操作功能而送出不同 BCD值。例如在面板平常使用时，该 BCD值将由 EEPROM 63〃中的 NDCV 所得到而送出相等的值； 但当进行 「标准点亮功率」 对 LED进行检测时， 该 BCD的值则必须由 EEPROM 61 "中的 SDCV取得所送出的值。
另外， PWM产生器 404"的任务周期大小则由 DSP50"所送出的资料 PWMD作比例的调整。当面板在正常使用时，其 PWMD值即相当于由「动 态区域亮度控制」所送入的 LACBD值； 但当进行「标准亮点功率」点亮各 LED进行检测时， 其 PWMD的为固定 50%的任务周期的 PWM值。 当然， 若利用可编程电流源 PCS 406"调校亮度， 则各组 LED 10"有一组对应的恒 流校正数据。
更深入探讨， 在前面各实施例中， 都假设各色 LED只有亮度衰减的问 题， 在衰减过程中， 其所发光的色度变化量均可忽略不计； 但实际长时间 使用后，各色 LED在亮度衰减的同时，也会引起些微小的色度变化。当 LED 晶粒产生此种发光频率分布的衰变时， 如果只调整各单色 LED的亮度， 使 其恢复到出厂标准， 则其色度之偏离并不能被补偿与恢复， 所以无法恢复 原来的色度要求。
如图 11所示， 例如后平面 103"'上设置一组分别针对红、 绿、 蓝测色 的三颗色度光学传感器 31"'、 32"'、 33'"， 量测多个设置在下平面 106'"上 的 「三合一」 发光二极管组 10'"。 其中， 色度光学传感器 31'"、 32'〃、 33〃' 是由三个分别配置有红、绿、蓝三片标准色滤光片 (color matched filter)的光 学传感器所形成。 由于色度光学传感器 31'"、 32'"、 33'"的频率响应并非仅 针对发光频率吻合的窄频响应， 即使是以绿色光照射至红色与蓝色的色度 光学传感器 31'"、 33'"， 仍有较低的光电流产出。
若绿色光的发光强度不变，发光频率向长波长 (红光)漂移， 则蓝色的色 度光学传感器 33"'响应的光电流将会减弱， 红色的色度光学传感器 31'"响 应的光电流则增强。 考虑各色度光学传感器 31"'、 32'"、 33'"对发光二极管 组 10'"所发的各色光均有不同感应值， 利用这些不同感应值的变化与否， 即可知各色光的衰变程度， 并利用混合该发光二极管组 10'"内的红、 绿、 蓝三个不同色光的驱动值来调整恢复原来的亮度及色度。
在背光板完成但尚未装置于面板之前， 先对每一个发光二极管组 10'" 的红、 绿、 蓝三色 LED, 利用厂内测光测色仪器测出该组红、 绿、 蓝三色 光的个别三个剌激值， 记为 Xk、 X2r> X3r及 Xlg、 X2g、 X3g及 Xlb、 X2b、 X3b 等 9个值， 其中 Xk、 X2r, 分别为该组红光 LED的三个刺激值， 其余类 推。 因此若该背光板内有 N组发光二极管组 10'"， 则必须利用厂内测光测 色仪测出该 9N个刺激值。
将背光板组装至面板后， 将面板液晶状态控制在全暗状态下， 利用前 述的 「标准点亮功率」， 逐一点亮发光二极管组 10'"内的各色光晶粒， 并记 录各该色度光学传感器 31"'、 32'"、 33'"的感应值， 例如当点亮该组中的红 色 LED晶粒时， 其三个感应值记为 x^、 x2r, x3r, 点亮绿色 LED晶粒时， 记为 xlg、 x2g、 x3g, 蓝色 LED晶粒则记为 xlb、 x2b、 x3b等； 并称这 9N个感 测值为 「标准感测值」。 而这 9N个 「标准感测值」 与前述所谓的 9N个刺 激值存在线性关系。 即各个 LED的各色光的刺激值与其感测值几乎有一定 的加权比例关系。
由于三个色度光学传感器 31'"、 32'"、 33'"的色滤光片大致与厂内的测 色测光仪器一致， 且如前所述， 各 LED在背光板内的反射路径也与色谱无 明确相关， 则由下列关系式可看出： 各色光的刺激值定义为
X JSj ZiWdA ,
其中， Sj( X )表示各色光的频谱能量大小， 且 j=r，g，b， 分别代表红、 绿、 蓝 三色光； Zi( X )为标准色滤光片的波长函数 (i=l,2，3， 代表红、 绿、 蓝三个标 准色函数)，而当该组 LED的该色光 (j=r，g，b)发光时的三色光感测值 (i=l，2，3， 分别代表 31"'，32'"， 33'"三个传感器)为： 其中， Ky分别表示各色光 (j=r,g，b)到各传感器 3r",32'"，33'"(i=l,2,3)反射系 数的大小， 而得到 Xij = KijXXy的关系。 因此该组 LED各色光的感测值 Xij 与其三个刺激值 Χϋ关系为：
Xii
Figure imgf000018_0001
2、 3， j= r、 g、 b)
因为刺激值 Xir代表红光成分， Xig代表绿光成分， Xib代表蓝光成分， 只要知道该组 LED的各色光在 X,、 X2、 X3的总成分， 即可代表该组的亮 度及色度。 此时， 定义
Figure imgf000018_0002
X20=X2r+X2g+X2b，
X30=X3r+X3g+¾b 则 X1()、 X2o、 X3G三个刺激值即可表示该组 LED的亮度及色度。 当该背光 板使用至 LED产生亮度及色度衰变时，如果能将该衰变后的各组 LED改变 其各色光的驱动权值发出不同光亮度的组合， 恢复该组的三个刺激值， 即 可以恢复其亮度及色度。
假设该组 LED的三色光经过衰变后， 不但其亮度衰减， 且其色度也改 变。 因此如果当使用过一段时间后， 利用前面所述的 「标准点亮功率」 逐 一点亮各组 LED内的各色光，并记录其在色度光学传感器 31'"、 32"'、 33"' 内的 「现时感测值」， 记为 Xi/ (i=l、 2、 3, j=r、 g、 b), 共可得到 9个 「现 时感测值」。 如果想要利用调整该组 LED内的各色光的相对驱动权值 、 Pg、 Pb (相对于出厂的单点校正值 DCV值之比例)来混色调整恢复原先的三 个刺激值 X1()、 X20> X3o， 其关系式可利用下列方法求出。 由于刺激值与感 测值成正比， 因此 LED衰减后的各个剌激值 Xi可由下式表示，
Figure imgf000019_0001
(i= l、 2、 3， j= r、 g、 b)…… (2)
如果该组红、 绿、 蓝各色光 LED各以 、 Pg、 Pb三个相对于原来出厂 时的 DCV值比例的相对驱动权值来推动发光，则其各自的刺激值将比例调 整为 PrXir'、 PgXig'、
Figure imgf000019_0002
l、 2、 3)o
如果要求该组 LED的 Xt、 X2、 X3的三个刺激值要回到原先的 X1Q、 X2o、 X3。的值， 则其关系为
Figure imgf000019_0003
PrX2g'+PgX2g'+PbX2b'=X20 (4)
Figure imgf000019_0004
代入 X¾ = Xij的关系， 则上列关系式可以改写为
hi. 十 rb-^ib - : x,n =x„+x1 ig„+x1 lb -(6)
Figure imgf000020_0001
上式 (6)、 （7)、 （8)可以改写为
Figure imgf000020_0002
利用方程式 (9)、（10)、 (11), 可解出 、 Pg、 Pb三个相对于出厂时 DCV 值比例的相对驱动权值。 由于方程式 (9)、 （10)、 （11)中， 各刺激值 Χ¾均在 背光板制作完成后， 利用厂内测色测光仪器量出， 己计算出其相对值， 例 如 Xir/Xio、 Xlg/ l0、
Figure imgf000020_0003
X2 ¾)、 X2g/¾0、 Χ2ΐ ¾)、 3 ¾0、 X3g/¾0、
X3b X3o等 9个值 (各值范围为 0~1之内)， 而且「标准感测值」 xlr、 xlg、 xlb、 x2r. x2g、 x2b、 、 x3g、 等 9个值也在出厂时利用背光板内的色度光学传 感器 31'"、 32"'、 33"'测出， 并记录于该内部 EEPROM内， 若再利用同一 组色度光学传感器 31"'、 32"'、 33'"在同一 「标准点亮功率」 下， 且控制在 同一面板液晶状态下量测出其「现时感测值」 xi > xlg'、 xlb'、 x2 、 x2g'、 x2b'、 x3 、 x3g'、 x3b' 9个值， 则可利用方程式 (9)、 （10)、 （11)算出该组 LED的各 色光的新相对驱动权值 、 Pg、 Pb来驱动该组 LED各色光的光亮度。如此， 该三色光的混合后的三个刺激值， 将恢复到出厂时的三个刺激值， 就使该 组 LED恢复到出厂的标准亮度及色度。
在本实施例中， 由于色度光学传感器 31'"、 32"'、 33'"均置有滤光片， 因此其感光灵敏度会比前面各实施例中的较小， 一般可能只有 20~30%左 右， 因而造成感测值的信号 /噪声比下降。 因此在感测值量测时， 可以利用 前面所述的 「同步相位检测法」， 利用数字信号处理器将信号加以 「同步相 位」处理， 以增加其信号 /噪声比。 另一个增加信号 /噪声比的方法就是加大 在做「标准感测值」 量测及「现时感测值」 量测时的所谓 「标准点亮功率」 值， 利用其较大的 「标准点亮功率」 值来弥补其较小的感光灵敏度。 例如 一般低功率 LED其驱动电流一般 「标准点亮功率」 下时， 其驱动电流为 20mA, PWM的任务周期 (duty-cycle)为 50%， 然而在本实施例中， 可以提 高其「标准点亮功率」为驱动电流 50mA， PWM任务周期为 50%的较高「标 准点亮功率」， 因此在量测 「标准感测值」 与 「现时感测值」 时， 其信号 / 噪声比将可以提高。
在同一个背光板内的不同区域的 LED, 由于其距离感光器的距离相差 很多倍， 因此在远距离的 LED宜选择较大的「标准点亮功率」来驱动感测。 但是同一组 LED的感测量测时 (即包括出厂所量测的「标准感测值」与「现 时感测值」 量测)所需的 「标准点亮功率」 必须一致。 因而在同一个背光板 内可视需要而有多组不同的 「标准点亮功率」 值， 这些数据也必须记录在 背光板内的 EEPROM中。
虽然前述各实施例均是以直照式的 LED背光板液晶显示器为例， 但对 于如图 12所示， LED 10""设置在背光板模块的侧面， 经由导光板 14'"'将 所发光束转向、 扩散的光源设计， 只要其 LED10""可被分别点亮， 也可通 过本发明的揭露而补偿其衰减； 且为提高信号 /噪声比， 亦可采增加光感测 面积的设计， 例如将太阳能电池 (solar celi '"'裁切至符合背光板内空间尺 寸， 分别设置在例如前、 后、 左、 右平面 101〃"、 103""、 104〃"、 102'〃'作 为光传感器， 而达成相同的衰减补偿功效。
依照上述方法， 根据分别感测与记录各组 LED被校正后的发光强度， 而在机体内适时且迅速感测、 经由处理装置的运算， 在使用者尚未察觉前， 实时对 LED的老化衰减进行补偿，确保各小区域中的 LED发光强度与色度， 完全被补偿至如同新品时的状态， 因此通过本发明确实可以有效达成本发 明的所有上述目的。
以上所述， 仅为本发明的较佳实施例而已， 但不能以此限定本发明实 施的范围， 即凡是依本发明申请专利范围及发明说明书内容所作的简单的 等效变化与修饰， 均应仍属本发明专利涵盖的范围内。

Claims

权 利 要 求 书
1、 一种 LED背光板液晶显示器衰减补偿方法， 该显示器包括一组液 晶显示模块； 具有多个 LED晶粒组的 LED背光板； 该显示器设置有至少 一组光学传感器； 一组向该 LED晶粒组供能， 并且输出电能可调的供能装 置； 一组储存有该液晶显示模块处于一个预定状态、且该等 LED晶粒组在 至少一个己知功率下逐一点亮时之该光学传感器感测值的储存装置； 及一 组接收该光学传感器感测值并控制该供能装置输出电能之处理装置。 所述 方法包括下列步骤：
a)在一预定时间， 限制所述液晶显示模块为所述预定状态， 且关闭所 述 LED晶粒组的电能供应；
b) 以所述储存装置所储存的所述至少一个已知功率点亮所述 LED 晶 粒组中的至少一组；
c)将所述光学传感器感测该 LED 晶粒组的感测值与所述储存装置中 预储存感测值比对；
d) 当所述感测值偏离所述预储存感测值达一个预定差值时， 由所述处 理装置驱动所述供能装置改变供应所述 LED晶粒的电能。
2、根据权利要求 1所述的衰减补偿方法， 更包括逐一点亮感测所述每 一 LED晶粒组直到所述 LED晶粒组全部被感测对比的循环步骤 e)。
3、根据权利要求 1所述的衰减补偿方法， 其中所述步骤 c)更包括同步 相位检测的步骤 cl)及对比步骤 c2)。
4、根据权利要求 1所述的衰减补偿方法， 更包括在步骤 a)前， 感测所 述预储存感测值的同步相位检测步骤 f)。
5、根据权利要求 1、 2、 3或 4所述的衰减补偿方法， 其中所述步骤 a) 所述预定状态是指所述液晶显示模块为完全关闭状态。
6、根据权利要求 1、 2、 3或 4所述的衰减补偿方法， 其中所述预定时 间是每一次所述显示器开机时。
7、根据权利要求 1、 2、 3或 4所述的衰减补偿方法， 其中所述预定时 间是当所述显示器被连续开机达到一个预定时段时。
8、 一种具有衰减补偿装置的 LED背光板液晶显示器， 包括： 一组液晶显示模块；
一组具有多个 LED晶粒组的 LED背光板；
至少一组光学传感器；
一组向所述 LED晶粒组供能， 且输出电能可调的供能装置； 一组储存有所述光学传感器感测值的储存装置， 该储存装置储存有在 所述液晶显示模块处于一个预定状态、所述 LED晶粒组在至少一个己知功 率下点亮时的所述光学传感器的感测值；
及一组处理装置， 当以所述储存装置所储存的所述已知功率点亮所述 LED 晶粒组中之一时， 所述处理装置接收来自所述光学传感器感测所述 LED晶粒组的感测值， 与所述储存装置中的所述预储存感测值比对， 且当 所述感测值与所述预存感测值达一个预定差值时， 控制所述供能装置改变 供应所述 LED晶粒组的电能。
9、根据权利要求 8所述的显示器， 其中所述光学传感器是一组光敏晶 体管。
10、 根据权利要求 8所述的显示器， 其中所述光学传感器是一组光电 二极管。
11、 根据权利要求 8所述的显示器， 其中所述光学传感器是一组测色 感光器。
12、 根据权利要求 8所述的显示器， 其中所述光学传感器是一组太阳 能电池。
13、 根据权利要求 8、 9、 10、 11或 12所述的显示器， 其中所述 LED 背光板设置有多个直照至所述液晶显示面板的 LED。
14、 根据权利要求 8、 9、 10、 11或 12所述的显示器， 更包括一组用 以放大所述光学传感器感测值的电压放大器、 及一组用以转换所述电压放 大器输出电信号的模拟 /数字转换器。 一
15、 根据权利要求 8、 9、 10、 11或 12所述的显示器， 其中所述供能 装置包括一组脉宽调变电路产生器。
16、 根据权利要求 8、 9、 10、 11或 12所述的显示器， 其中所述供能 装置包括一组可编程电流源。
PCT/CN2008/000824 2008-04-22 2008-04-22 液晶显示器led背光装置的衰减补偿方法和液晶显示器 WO2009129650A1 (zh)

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Publication number Priority date Publication date Assignee Title
CN1517968A (zh) * 2003-01-24 2004-08-04 三星电子株式会社 用于液晶设备的背光驱动设备
CN1721943A (zh) * 2004-07-12 2006-01-18 索尼株式会社 显示单元与背光单元
CN1746743A (zh) * 2004-09-07 2006-03-15 安捷伦科技有限公司 使用多个光传感器调整用于显示器的直亮式背光
CN1842923A (zh) * 2004-07-12 2006-10-04 索尼株式会社 用于驱动背光单元的装置和方法
CN100360999C (zh) * 2003-11-27 2008-01-09 三星Sdi株式会社 场序液晶显示器
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