TWM339775U - LED backlight plate liquid crystal display having decay-compensation apparatus - Google Patents

Description

M339775 VIII. New description: [New technical field] The present invention relates to a display, in particular to an LED backlight liquid crystal display having an attenuation compensation device. [Prior Art] Using the red, green and blue LEDs as the light source of the backlight board, the biggest advantage is that the light emission frequency is relatively pure, so that the color gamut can cover about 130% of the NTSC standard, so that the viewer can feel More colorful color changes. In recent years, 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 can also reduce the dynamic image blur of dynamic images. In addition, it has been proposed to use three-color light timing to drive the light, eliminating the use of color filters for color-filterless LCD-TV. Direct-illuminated area-controlled backlights that use red, green, and blue LEDs as light sources will also become increasingly popular. Of course, not only three colors of independent LEDs can be used as the light source, but also a so-called "three-in-one" three-color integrated LED, which has better uniformity in color and brightness, and is cheaper in price, and the market acceptance is also increasing. Since the luminous efficiencies of the LEDs are all different, in order to obtain a common uniform brightness at the factory, after each LED is disposed on the backlight panel, the in-plant photometric color measuring instrument is used to measure the color of each LED or each group of LEDs. The brightness and chromaticity are calculated according to the brightness and chromaticity requirements of the backlight. The Dot Correcting Value (DCV) of each LED is obtained. The storage frequency 5 M339775 records these DCV values and is used to weight the LEDs. When the LEDs on the backlight panel are lit, the same chromaticity and brightness are exhibited. Therefore, these values are called "Standard Dot Correcting Value". However, the biggest disadvantage of the 'direct-lit backlight board is that the light intensity will be attenuated after the LED is used for a long time, and if the LEDs with three colors are separated, the speed of the other J is reduced, even if the LED of the same color is affected. Limited to the manufacturing conditions and the difference in ambient temperature, but with different attenuation speeds, resulting in uneven brightness and chromaticity of each area of a backlight panel, deviating from the standard requirements and affecting the quality of LCD-TV; even using white LED as a light source The attenuation speed of each LED die is different, which still causes the problem of uneven brightness and chromaticity between regions. In particular, the sensitivity of the human eye is quite high, and it is even more unbearable for the aging of such products. In the prior art, one or several chromatic sensors (col〇r_photometry sensors) are used to measure the three "tri-stimulus values" of the red, green and blue of the entire backlight in the fully bright state. ), and using the magnitude of the three stimulus values, adjust the weight ratio of the red, green, and blue lights of the entire backlight panel, thereby controlling the overall illumination brightness and white balance of all the LEDs. To compensate for the aging decay phenomenon, the measured value is also used as a reference weighting calculation to increase the total supply energy to enhance the overall brightness and total chromaticity of the overall backlight. With this method, although the average total brightness and total chromaticity of the entire backlight panel can be restored, but the one-to-one adjustment compensation of the attenuation of the individual LEDs cannot be performed, the brightness and chromaticity of each small area are aging due to individual LEDs. 6 M339775 == Dynamic Backlight Area Control" The brightness and color 2 caused by the process is not repaired. Still: The quality deterioration of the 0+ board cannot be fully compensated. Therefore: (9) provide a device that can be self-purified, has (four) and separately test each, reduce the degree of damage, and individually compensate, and undoubtedly maintain the image quality of the display with backlight, so that it will remain new at the end of its useful life. The brightness and uniformity of the light, and the best

solution. [New content] Therefore, an object of the present invention is to provide an LED backlight panel liquid crystal display capable of accurately detecting the degree of sag of each group of LEDs and compensating them separately. Another object of the present invention is to provide an LED backlight panel liquid crystal display that automatically detects the degree of attenuation of each group of LEDs and compensates them separately. A further object of the present invention is to provide an LED backlight panel liquid crystal display that quickly detects the degree of attenuation of each group of LEDs and compensates them separately. Therefore, the LED backlight panel liquid crystal display having the attenuation compensation device includes a set of liquid crystal display modules; the LED backlight panel has a plurality of LED chip groups, and the display is provided with at least one set of optical sensors, a power generating device capable of outputting the LED chip groups and outputting electric energy, a processing device for receiving the optical sensor sensing value and controlling the output power of the energy supply device, and a group of the liquid crystal display The storage device for sensing the optical sensor when the module is in a predetermined state and the LED chip groups are illuminated one by one at least one known power, the 7 M339775 method comprising the steps of: a) Resetting the liquid crystal display mode to the predetermined state and turning off the power supply of the LED die groups; b) illuminating the LED die groups with the at least one known power stored by the storage device At least - the group; c) sensing the sensed value of the set of coffee chips with the pre-stored sensed value in the storage device; and d) when the sensed value deviates from the pre-stored sense Value up to a reservation The gap is driven by the processing device to vary the power supplied to the LED die. • With this new model, not only the interference of external optical noise is effectively eliminated, but also the degree of attenuation of each group of LED dies is quickly and accurately checked, so that the compensation is instantaneous and the illumination intensity and chromaticity of each area of the display are as new as possible. DETAILED DESCRIPTION OF THE INVENTION The detailed description of the preferred embodiments of the present invention will be apparent from the description of the preferred embodiments. In response to the above problems, the first embodiment of the novel display is as shown in the figure! The invention includes a group of backlights having a plurality of LED chip groups, a group of liquid crystal display modules that are shielded from the moonlight panel, and a set of optical sensing H's The energy supply device 4 of the above LED chip group, a set of examples is a processing device $ including a digital processor Dsp 5, and a set of storage devices 6. In this example, the storage device includes non-volatile memory EEPROM 6 i, EEPR 〇 m 62 and EEPROM 63 for storing the above-mentioned SDC V, etc. In this example, as shown in FIG. 2, for example, two The illuminating red monochromatic LED dies are connected in series as a set of led die groups ι〇, and are illuminated by the single-group 8 M339775 current driving circuit (LED current driver) 40, and the current driving circuit 40 includes an analogy. An analog switch AS 402, a constant current source Iso 400, and a pulse width modulation circuit PWM generator 404. The PWM generator 404 generates PWM waves of different duty-cycle ratios according to the data of the "Brightness Control Data BCD" value. Therefore, the average brightness of the LED group 10 will be determined by the constant current source Iso 400 and the duty cycle ratio. In this example, the constant current source Iso 400 of each group of LEDs 10 will be unchanged, 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-bit can provide 256-order brightness control, 1 bit can provide 1024-order brightness control, and 12-bit 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. Generally, at the time of shipment, the LED luminous intensity is only about 60~70% of its maximum brightness, so when the LED luminous intensity is reduced, the difference can be used to improve the brightness of the LED. As shown in Fig. 3, in this example, LEDs of three colors of red, green, and blue, respectively, are arrayed by a complex array to form a matrix (ixj), which is used as a backlight source, and the illumination of the backlight is formed by a direct illumination method. The appearance of the backlight panel is roughly _ six-sided hollow box-shaped structure, and the six sides are respectively marked as the front and rear planes 1 (n, 103, left and right planes 104, 102, and the upper and lower planes are 1〇5, 1〇). 6. The other five faces 101, 102, 103, 104, 106 may be made of plastic or metal, except that the upper surface 105 is a light-emitting surface, and the light-emitting surface is provided. A reflective surface or a total reflection film; the light reflected from the 9 M339775 LED chip group i 〇 output and not reflected by the light-emitting surface is reflected to the upper plane 经由 through the panel to increase the efficiency of the backlight output light. A diffusion sheet 12 is disposed on the upper surface 105 as a light-emitting surface, so that the light that directly illuminates the LED is uniformly diffused and uniformized under the regional illumination characteristics in which the LEDs are retained. In this example, the diffusion sheet 丨2 Further, there are other panel structures 〇2〇, and a photo-crystal 3 as an optical sensor (〇ptical sens〇r) is placed at an appropriate position in the center of the lower plane 1〇6, for example. Measure the brightness of the light from the LED die group 1。. As shown in Figure 4, photoelectric The body 3 is connected in series with the load resistor R1 as a current-voltage conversion, and then passed through a voltage amplifier (Voltage Amplifier) VA 52, which can select, for example, X i, X 10' X 100' X 1000, etc. 4 gains (v〇itage gain range c〇ntr〇1) of different gains to different ranges of photocurrents generated by LEDs of different distances. The gain is selected by the gain file GR sent by DSP 50 Since the distance between each group of LEDs and the optical sensor is much 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. a/D The digital signal output of the converter 54 is sent to the DSP 50 for processing. Since the backlight 1 is mounted behind the liquid crystal display module 2 (including a glass substrate, a liquid crystal, a color filter, a polarizing film, a TFT glass, etc.), the display is When the optical sensor detects the brightness of the LED by the optical sensor, the brightness of each group of LEDs reflected back to the optical sensor will be affected by the following factors: (1) each of the backlights The reflection coefficient of the surface; (2) the reflection coefficient of each optical surface structure in the M339775 liquid crystal display module; (3) the degree of opening/closing of the liquid crystal valve; (4) the amount of incident light of the external ambient light, etc. The first two factors It is a backlight panel and a 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 controlling the liquid crystal valve in a specific state during the test. When it is completely dark, it can be determined that the liquid crystal molecules are completely closed. At this time, the reflected or diffused light of the led LED will be fixed; and when the liquid crystal is fully closed, the incident light from the external environment is also screened in a large amount and cannot enter the machine, and the external ambient light can be reduced to the optical sensor. Impact. The above factor (4), on the one hand, because the optical power of each group of LEDs is not large, and only a very small part of the reflected light or diffused light is detected by the optical sensor; conversely, although The liquid crystal valve can be controlled to be fully closed, but the external light may be very strong, and some light leakage may affect the optical sensor to form background light interference, which affects the accuracy of detection. Therefore, the present invention further proposes a "synchronous phase detection" process for processing the optical sensor's sensed value by DSp as shown in FIG. 5, similar to an analog lock-in amplifier function, which sends the Dsp. The BCD value is fixed at a value of 5〇% of the pulse width modulation task period, and the integration of the positive and negative phases is performed by the synchronization phase (that is, the positive phase is added, the negative phase is subtracted), for example, the BCD is transmitted by a 10-bit data group. To the pwM generator, when BCD=1023, it is 1〇0% of the task cycle. At this time, the BCD value sent by Dsp will be 512, so that the PWM generates a square wave of 5〇%High and %% Low to drive the LED. Glowing. M339775 Because the ci〇ck of the PWM generator is sent by the DSP, the DSP can use this clock to synchronize the processing of the plus and minus data of the positive and negative phases. When the pulse is High, the analog switch is on, enabling Led to emit light, and the other 50% Low period, the analog switch 〇FF, so that the LED does not emit light in the negative phase, the LED light is different through the interior of the backlight panel and the panel. The structure is reflected back to the photo-electric crystal 3, and its photocurrent "produces just in synchronization with whether the LED is illuminated. The DSP is in the 50% half cycle of High 81, 83, 85... accumulate data from A/D" and in l〇 The 50% half cycle of w, 82, 84, 86... subtracts the data from A/D, so during the positive and negative phase addition and subtraction of the synchronous phase, the sensed value of the positive phase will be gradually strengthened, and the negative phase has no light, no The value can be reduced; the more the cumulative period processed by the DSP, the larger the accumulated value of the sensed value. Conversely, the 'normal ambient light is mostly DC or slow-changing ambient light' is also measured by the optical sensor. Or a signal that changes slowly. The sensed value generated by the ambient light enters the DSP. The 50% half cycle of High, 81, 83, 85... is added, and the 50% half cycle of Low is 82, 84, 86... Minus, because the ambient light is almost DC or slow, so regardless of High or Low Cycle, the signal In is almost equal, so the DSP makes positive and negative phase addition and subtraction, the sensed values are almost offset each other. With the above method, the processed data in the DSP only has the sensed value generated by the LED light. 'Significantly increase the ratio of the light sensing value of the LED to the ambient light sensing value, so as to almost completely eliminate the influence of ambient light. Since the LED chip group 1 in the backlight panel has the geometrical position and optical reflection path of the photoelectric crystal 3 Do not change at any time, refer to Figure 4 and Figure 6 12 M339775. After the adjustment of the light board is completed and the display is completed after the whole machine is assembled, the display is first adjusted to the full dark condition, and the power is supplied. In the device, & each corresponding current driving circuit outputs to each LED chip group (i, j) one by one, for example, the same known power, sequentially lighting each group of ledi〇 in the backlight board; For the sake of reference, this known power is hereinafter referred to as "standard lighting power". In order to be able to adjust the attenuation compensation of the LED die group 1〇 in the future, it is necessary to detect the attenuation of each group of LEDs first. The so-called attenuation amount is the standard luminance difference between the LED after use and before the waste, so in step 72, the value of the photoelectric crystal 3 is sensed by the digital signal processor (DSP) to perform the above-mentioned "synchronous phase detection" processing because This sensed value is measured before the LED die is not attenuated, so it is called "Standard Sensing Data"; and this sensed value and its corresponding voltage gain file GR(i,j) Recorded in EEPROM 62 towel. Thus, the record of the relative optical power of each group of LEDs (including different color lights) is established as the basis for judging the judgment of the LED _ attenuation amount and the compensation adjustment in the future. In this example, the step 73 of the attenuation detection is automatically performed every time the display is turned on, and the liquid crystal display device of the display is controlled to be fully turned off, and each of the above-mentioned "standard lighting powers" is used to light each of them. ,, 'LED (i, j) monochromatic light source. And in step 74, the voltage gain of the photovoltage generated by the light is processed by using the voltage gain file GWi stored in the EEPROM corresponding to the position (i, j), and the A(7) conversion value of the photovoltage after the gain is used. After the DSP "synchronous phase detection" processing, the sensing value of each color light is obtained. For the sake of distinction, it is called "currently 13 M339775 sensing data, CSD(i, j)". The DSP finds the "standard sensing value SSD(i,j)" and the "standard single point correction value SDCV" corresponding to the group LEDs in the storage device in step 75, and uses the following relationship to find the following "new" Single point correction value NDCV (New Dot Correcting Value)··· NDCV=SDCVxSSD/CSD.......(1) In this example, it is assumed that the system has a signal-to-noise ratio (S/N) of 33 times, so when NDCV When the difference between the previously stored values reaches a predetermined value, for example, 3%, it is convenient for step 76 to store the new single-point correction value NDCV in the EEPROM 63 as the brightness compensation correction data of the adjusted LEDs. When the panel is in normal use, the backlight panel 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 by the LCD module. The LACBD value is determined, but each group of LEDs is subjected to the aforementioned correction. Therefore, 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 it is determined in step 77 whether compensation is required. If the brightness is significantly changed, in step 78, the DSP 50 multiplies the required brightness value LACBD sent by the "dynamic area brightness control" with the "new single point correction value NDCV" as shown in FIG. Taking some suitable high-order elements as the "brightness control value BCD" of the LEDs, and sending them to the PWM generator 404, thereby increasing the duty cycle ratio of the corresponding PWM to increase the brightness of the set of LEDs 10, and returning to the original standard. To maintain the brightness and chromaticity of the factory. Of course, as can be easily understood by those skilled in the art, the foregoing embodiment of the M339775 J exemplifies that the "group" LED is a plurality of LEDs that are illuminated by the same set of circuits, but in practice, it can also be a single The lEDs act as a group, or a plurality of circuits in an adjacent small area to drive the plurality of lEDs to form a group of LED chips, which are collectively corrected and compensated. In addition, since the luminous intensity of the LED sometimes rises and then drops, the compensation is not a duty-saving ratio of the driving signal. And since the sensing compensation program is all in the body, it can be corrected and adjusted at any time, not limited to when the machine is turned on, or can be scheduled in each operation, for example, one thousand hours, shutdown, or user button calibration. The time is automatically detected and compensated to achieve a new feeling of brightness and chromaticity throughout the display and backlight. Here, a 42-inch LED backlight LCD-TV is taken as an example, and the size of the backlight is as shown in FIG. 8, wherein the Si photodiode 3' is placed at the center of the backlight, and if the LED1CT is the farthest one, The light of the photodiode 3' is affected by the area a=1 〇cm2, and its light sensitivity (ph〇t〇-resp〇nsitivity) is RS=0.4A/W in blue light, and LEDliV is a general low-power LED at 10 180= 2〇111 eight o'clock, its blue light power? 1=5 111\¥, then 1^010, when light is emitted, the photocurrent generated by the photodiode 3' can be calculated by the following steps: (1) The LED 10' passes through the upper plane 105', the diffusion film, or the panel The proportion of the part reflected back was set to 30%, of which 20% was diffused (80/20 transmission/reflection ratio) and the other 1% was reflected by the panel structure. (2) Therefore, Pr = 1.5 mw of the optical power pI == 5 mw emitted by the LED 10' is reflected back. (3) Assume that the reflected Pr=l.5mw optical power will be evenly distributed to the entire lower plane 106f in a diffuse manner with a total solid angle of 27 Γ. 15 M339775 (4) The receiving area of the photodiode 3' is a = 1 〇 cm2, which contains the solid angle acos0 ′ where L2 y +32 three 3000cm2 L = 55cm C〇S0=iT〇·055

ΔΩ = 2χ1〇·5

(5) Therefore, the optical power received by the photo-electric crystal 3' ρ = Ρ X = 5 x l (T9W m r 2π

(6) Photocurrent generated by photodiode 3f = RsxPin = 〇 4A / Wx5 〇χ 10'9w = 2.0x10'9A = 2 nA (7) There are two main sources of noise in the S circuit, one of which is the load. The thermal noise current In of the resistor R1 has a size of In2=4kT/RL Af, where k is a Boltzmann constant and T is a backlight temperature 'Δf is a bandwidth. If the PWM frequency is fw=30KHz, then △ 3fw is required, △ f=i〇〇KHz, RL=100KD, then the hot machine current Ir^O.HnA 'the original photocurrent/noise ratio (S/ N)=2/0.14 = 14 times. (8) Input the signal of the photocurrent plus noise into the amplifier, enter the DSP after a/D conversion and perform the "synchronous phase detection" process. When each group of LEDs is required to be processed in the ims, even if there is one in the backlight Thousands of LED die sets can also be tested in one second. Because 16 M339775, the integration time of this DSP is limited to ims, and • Compared with the photocurrent signal with PWM frequency of 30KHz, DSP can accumulate 30 sensed values in lms to make s/N ratio At least synchronous promotion # three 5·5 times. That is, the S/N ratio after processing by the DSP "synchronous phase detection" can be about 77 times. The resulting LED sensing value can be used to determine the attenuation amount very accurately, with an accuracy of about 1.3%. (9) As mentioned in (7) above, another source of noise is the ambient light. • The severity of the disturbance varies depending on the ambient light. Assume that the outer ring of the Gusuke is 1000 lux', that is, 1000 lm/m2, which is equivalent to the light power illumination of 1.5 W/m2. Generally, when the liquid crystal valve is fully open, about 10% of the light can be transmitted to the backlight. However, if the liquid crystal valve is fully closed, it is only about 1/500 of the full opening. Therefore, if the LCD valve is required to be fully turned off when testing the LED, then in this case, the ambient light is transmitted to the backlight. The optical power illumination is about 0.3 mw/m2, and the illuminance is in the area of the photoelectric crystal a=icm2. _ The incident light power pin(ainbient) = 0.3xl 〇 -7w on the receiving surface. Compared with the LED light calculated by the previous formula, the photoreceptor optical power = 0.5xl0_8w, the incidence of ambient light is greater than the incident of led light. The amount is about 6 times larger. Similarly, since the ambient light can be regarded as almost DC or the change is very slow (generally within 6 Hz), as described above, after the DSP performs positive and negative phase addition and subtraction 3 times, the sensed value will decrease. More than 30 times, and the sensing signal of the LED will increase by 30 times due to the synchronization relationship. Therefore, the ratio of the sensing value generated by the optical power of the LED to the sensing value of the ambient light will be increased to 3〇/(6/3q). 17 M339775 = 9〇〇/6=150 times. Therefore, the attenuation of the LED can be judged very accurately, and its accuracy can reach about 0.6%. *The above description is for the farthest coffee from the optical sensor. If a certain LED is only 4 coffees away from the optical sensor, according to the above calculation, the light current generated by the LED to the photoelectric crystal It is about ^ A, its size is about 2 times the photocurrent generated by the farthest LED, and the gain of the voltage amplifier (10) of the latter stage must be reduced to the heart, otherwise the voltage will reach saturation. Of course, as can be easily understood by those skilled in the art, the above-mentioned "standard force rate" can also select a plurality of powers different from each other, and the distance from the optical scent detector is used as a standard, and the lighting power in the vicinity is relatively high. Low, far from the point of power, only need to be the same as the lighting conditions when the record is established before leaving the factory. In addition, as shown in the second preferred embodiment of the present invention, as shown in the second preferred embodiment of the present invention, the diffusion sheet 12' front plane 1〇1,, right plane ι〇2,, left plane just", upper Planar 1〇5”, other structures 12〇,, processing device voltage amplifier (VA) 52'', analog/digital converter (A/D) 54”, storage device 6”, non-volatile memory (EEPR〇 m) 62", circuit 40, 'etc. will not be described again. Among them, the LED can not only use monochromatic illumination, but also can choose to set a plurality of LED crystals of three different colors on the lower plane 106", and package the same into one The so-called "three-in-one" led color LEDs, ,, 乂 each LED is a group, forming a matrix of fixed pitch (ixj) arrangement. Since the moonlight panel contains a plurality of matrix arrays (ixj) LED10", the number: K = i Xj therefore requires a total of 3N "standard single point correction value" SDCV, this data must be stored in a non-volatile memory EEpR 〇M 6丨,,中中. 18 M339775 In this example, a plurality of optical sensors 3 are placed, for example, on the back plane 103〃. The sensitivities of these optical sensors can be added together to be used as a single unit, thereby increasing sensitivity. (sensing-sensitivity). The optical sensor 3 can also be a wide-spectrum optical sensor of a photodiode or other material, as long as the above-mentioned bismuth (Si) photo-crystal is removed, as long as it has responsibility in the visible light spectrum. The sensitivity of the spectrum may not be equal; the optical sensor may also be separately covered with a chromatic light sensor composed of red, green and blue three-band filters. Even if the distance and orientation of each optical sensor 3〃 and each LED 10〃 are different, the reflection coefficient of the optical path is different, so that the photo-response of each LED 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 sensitivity does not change. Therefore, the same "standard lighting power" is repeatedly used to light each Corresponding to LED 10〃, if the sensed value is changed after optical metering, the effect of the LED attenuation can be clearly analyzed and compensated. In this example, the enable LED is not controlled by the cycle-to-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 obtained by the NDCV in the EEPROM 63" and the same value will be sent; but when the "standard lighting power" is used to detect the LED, the value of the 19 M339775 BCD must be The sdcv in EEpR〇M 61" takes the value sent. In addition, the duty cycle of the PWM generator 404'' is adjusted by DSp5〇, and the data pWMD sent is proportionally adjusted. When the panel is in normal use, its PWMD value is equivalent to the LACBD value sent by the "dynamic area brightness control". However, when "standard bright spot power" is performed and each LE is turned on for detection, the PWMD is Fixed a pwM • value of 50% of the task period. Of course, if the programmable current source PCS 406 is used to adjust the brightness, each group of LEDs 10" has a corresponding set of constant current correction data. In more detail, in the foregoing embodiments, it is assumed that each color LED has only a certain attenuation. The problem is that during the decay process, the amount of chromaticity change of the luminescence is negligible; but after the actual use for a long time, each color will cause a slight chromaticity change in the case of the shell attenuation. When the lED grain is produced When such a luminous frequency distribution is degraded, 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 recovered by _, so the original chromaticity requirement cannot be restored. As shown in FIG. 11, for example, 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 the plurality of measurement are set in the lower plane. "Three in one" LED group 10 on 1〇6... Wherein, the chromaticity optical sensors 3Γ,,, 32..., 33... are two optical sensors respectively configured with three standard color filters of red, green and blue (c〇1〇r matched filter). Formed. Since the frequency response of the chrominance optical sensors 3 Γ", 32..., 33... is not only for the narrow frequency response of the illuminating frequency, even the green light is irradiated to the chromaticity of the red and blue opacity 20 M339775 detector 31..., 33..., there is still a low photocurrent output. If the luminous intensity of green light does not change, the luminous frequency drifts to a long wavelength (red light), then the blue chromatic optical sensor 33〃, response The photocurrent will be weakened, and the photocurrent of the red chrominance optical sensor 31... is enhanced. Considering the colors of the chromaticity optical sensors 3Γ, 32..., 33... for the LED group 10 Light has different sensing values. By using these different sensing values, the degree of decay of each color light can be known, and the driving of three different color lights of red, green and blue in the light-emitting one-pole group 10"' can be used. The value is adjusted to restore the original brightness and chromaticity. Before the moonlight board is formed but not yet installed in the panel, the in-plant metering is used for each of the LEDs, the red, green and blue LEDs of the group 10... The color measuring instrument measures the red, green and blue colors of the group. The individual three stimulus values are recorded as xlr, x2r, x3r & Xlg, X2g, x3g & Xib, X2b, X3j 9 values, where xlr, each is the three stimulus values of the group of red light led, and so on. If there are N sets of LEDs and Guard 10 in the backlight, the 9N stimuli value must be measured by the on-site photometric color measuring instrument. After assembling the moonlight panel to the panel, the panel liquid crystal state is controlled in the full dark state. Using the aforementioned "standard lighting power", lighting the light crystal grains of the light-emitting diode group one by one, and recording each of the color optical sensors

The sensing value, for example, when lighting the red crystal in the group, the three sensing values are recorded as x3r, when the green LED is pulled, it is recorded as x, g, X2g, X3g, and the blue led die is It is recorded as ^, ~, and so on; and these 9N sensed values are referred to as "standard sensed values". The state's "standard sensed value" is linear with the so-called 9n stimulus values. 21 M339775 is present. That is, the stimulus value of each color of each LED has a certain weighted proportional relationship with its sensed value. Because the color filters of the three chrominance optical sensors 31'", 32,,, 33... are substantially identical to the colorimetric metering instruments in the factory, and as described above, the LEDs are in the backlight panel. The reflection path is also not clearly related to the chromatogram, and it can be seen from the following relationship: the stimulus value of each color light is defined as

Xij卞(1)Zi(1)(U, # where Sj( λ ) represents the spectral energy of each color of light, and j=r, g, b, representing red, green and blue light respectively; Zi(1) is the wavelength function of the standard color filter (i=l, 2, 3, representing three standard color functions of red, green, and blue), and the three-color light sensing value when the color light (j=r, g, b) of the group of LEDs emits light (Bu 1 , 2, 3 'representing 31..., 32..., 33~three sensors respectively)

Xu ^KjSj(1)4 (also >1 and where 'Kij respectively represents the magnitude of the reflection coefficient of each color light (j=r5g, b) to each sensor 31〃, 32”', 33〃^(b 1, 2, 3) And get the relationship of [= KijXXij. Therefore, the sensed value Xij of each group of LED lights and its three stimulus values Xij are χϋ -Κ. χΧυ (ί = 1, 2, 3, j = r, g, b Because the stimulus value 乂1 represents the red component, & represents the green component, and & represents the blue component, as long as the color of each group of LEDs is known to be the total composition of X1, χ2, X3, it can represent the brightness of the group and Chroma. At this time, define Xi〇-Xlr+Xlg+Xlb, X20-X2r + X2g + X2b ' X3 0~-X3r + X3g + 22 M339775 Then the three stimulus values of XiQ, X2〇, Χπ can represent the group. The brightness and chromaticity of the LED. When the backlight is used until the LED produces brightness and chrominance decay, if the LEDs of the respective LEDs are changed, the driving weights of the respective colors of light are emitted with different brightness. Combine and restore the three stimulus values of the group, that is, it can restore its brightness and chromaticity.

Assuming that the three-color light of the group of LEDs decays, not only does its luminance decrease, but its chromaticity also changes. Therefore, if after using for a period of time, the "standard lighting power" described in the face is used to illuminate each color light in each group of LEDs and record it in the chromaticity optical sensor 3 1, "32", The "current sensed value" in , 33... is denoted as Xij, (i = 1, 2, 3, j = f, §, b), /, port τ ] 9N current sensed values". If you want to adjust the relative driving weights Ug, Pb of the respective colors in the group (4) (relative to the ratio of the factory single point positive value DCV value) to the color mixing adjustment to restore the original three stimulus values x10, x20, X3 〇, the relationship can be found by the following method.

Since the stimulus value is proportional to the sensed value, the respective stimulus values X/ after the attenuation of & (4) can be expressed by the following equation.

Lx, X: (1= 1, 2, 3, j= r, g, b)... (2) Blue LEDs of each color, pg, pb If the group of red and green is relative to the original The relative (four) weight of the ratio of DCV values at the factory to promote illuminance, the individual stimulus values are adjusted to PrX:, ρ χ , and PbXuZ (Bu 1, 2, 3). Lr S W, if the three stimulus values of the group LE(4)Χ1,Χ2,Χ3 are required to return to the original values of Χΐ0, Χ2°, χ30, the relationship is 23 M339775

PrXr+PgX^'+PbXb^o........(3

PrX2g, +PgX2g'+pbX2b'=X20........(4)

PrX3g +PgX3g'+PbX3b'=X3〇........(5) Then the above relation can be rewritten as the relationship of Xy = fXij, xij

PrXlA + PgXlg^ + PbX

Υ 6 klg Xlr X lg prx2A+pex, & lb lb lb

X

:Xl〇=Xlr +Xie +X lg C+v^+PbX< = X2〇=X2r+X2八prx3r^-+pgx3g^+pbx3bx 3g — + PbX3b = x30 = X3r + X + x L3g L3b 6), (7), (8) can be rewritten as --(6)...(7) ...(8) X, v X, , XlO People Xlr (x v-

X

P 2r vXioy pr +

X

X lg

X X , XlO People Xlb lb fx

X lb

Pb (9) (10) _2r_ ^^•20 j lX2rJ 2g X 20 2g VIII V _2b_ VX2b Pb

Using equations (9), (10), and (11), the relative drive weights of pr, pg, and pb relative to the factory DCV value ratio can be solved. Since in Equations (9), (10), and (11), each stimulus value Xij is measured by the in-plant colorimetric meter after the backlight is manufactured, and the relative value has been calculated, for example.

Xlr/XlO ' Xlg/XlO ^ Xlb/Xio ^ X2r/X2〇^ X2g/X2〇> X2b/X2〇, X3r/X30, X3g/X30, X3b/X3〇, etc. 9 values (each value range is 〇 ~! Within), 24 M339775 and "standard sensing value" Xu, Xig, Xib, Xh, X2g, X2b, X3r, X3g, X3b and other 9 values are also shipped with chromatic optical sensing in the backlight The devices 3Γ〃, 32〃', 33... are measured and recorded in the internal EEPROM. If the same set of chromaticity optical sensors 31..., 32..., 33... are used under the same “standard lighting power”, And the control can measure the current day sensing values "xlr', xlg', Xib', X2g', x2b', Χ3ι/, h〆, xsb' in the same panel liquid crystal state, then the equation can be used. (9), (1〇), (11) Calculate the new relative driving weights pr, Pg, and pb of the respective color lights of the group of LEDs to drive the brightness of each color light of the group of LEDs. Thus, the three stimuli values of the three colors of light will return to the factory tristimulus values, and the set of lEDs will be returned to the factory standard brightness and chromaticity. In this example, since the chromaticity optical sensors 31..., 32..., 33, and white are provided with filters, the sensitivity of the photosensitivity may be smaller than that of the previous embodiments, generally only 20 to 30. About %, thus causing a decrease in the signal/noise ratio of the sensed value. Therefore, in the measurement of the sensed value, the "synchronous phase detection" method described above can be used to add the signal to the "synchronous phase" process by the digital signal processor to increase its signal/noise ratio. Another way to increase the signal ratio is to increase the so-called "standard lighting power" value of the "standard sensing value" measurement and the "current sensing value", and use the larger "standard lighting power". Value to compensate for its small sensitivity. For example, when the driving current of a low-power LED is generally "standard lighting power", the driving current is 20 mA, and the duty cycle (duty_cycle) of the PWM is 50%. However, in this embodiment, the "standard lighting" can be improved. The power is the higher the "25 M339775 quasi-point shell power" with a drive current of 5 〇 mA and a PWM duty cycle of 5 〇 %. Therefore, when measuring the "standard sensed value" and the "current sensed value", its signal / The noise ratio will be improved. LEDs in different areas of the same backlight panel are driven by the long-distance LEDs by selecting a larger "standard lighting power" because the distance from the sense of light is many times different. However, the "standard lighting power" required for the sensing measurement of the same group of LEDs (that is, the measurement of the "standard sensing value" and the "current sensing value" measured by the factory) must be the same. Therefore, there are multiple sets of different "standard lighting power" values in the same backlight panel as needed, and these materials must also be recorded in the eeprom in the backlight panel. Although the foregoing embodiments are all in direct illumination type with LEDs. The backlight panel liquid crystal display is taken as an example, but as shown in FIG. 12, the LED is disposed on the side of the backlight panel module, and the light source beam is diverted and diffused by the light guide panel 14 as long as the LED 1 (r... can be respectively pointed Bright, can also compensate for the attenuation by the disclosure of this case; and to improve the signal / noise ratio, can also increase the design of the light sensing area, such as the solar cell (sol set - cut to fit the backlight) ^ The dimensions are set to, for example, the front, back, left, and right planes 10, ..., 103,, ", 104,,,,, 102,," as the light sensor to achieve the same attenuation compensation effect. In the above method, by sensing and recording the illuminating intensity of each group of LEDs respectively, and timely and quickly sensing in the body, and operating through the processing device, the aging attenuation of the LED is immediately before the user is aware of the aging. Make compensation It is ensured that the illuminating intensity and chromaticity in each small area are completely compensated to the state like the new product. Therefore, the above-mentioned purpose of the present invention can be effectively achieved by the invention 26 M339775. The preferred embodiment is not limited to the scope of the present invention, that is, the simple equivalent changes and modifications made in accordance with the scope of the novel application and the contents of the new specification should still be within the scope of the present patent. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first preferred embodiment of the present invention; FIG. 2 is a schematic diagram of an LED die group and a current driving circuit of FIG. 1; FIG. 3 is a schematic structural view of the backlight panel of FIG. Figure 5 is a schematic diagram of the circuit of the synchronous phase detection process; Figure 6 is a flow chart of the display attenuation compensation method of the present invention; Figure 7 is a circuit diagram of Figure 1 illustrating the attenuation compensation process; A perspective view of a 42-inch LED backlight panel, showing how the most corner LED is detected by an optical sensor; FIG. 9 is a perspective view of the backlight panel of the second preferred embodiment of the present invention. FIG. 11 is a schematic diagram of a circuit board according to 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; and 'dry standing=12 is a backlight unit of the fourth preferred embodiment of the present invention. Three-dimensional structure [Description of main components] 1...Backlight 2···Liquid crystal display module 27 M339775 3, 3', 3'.. Photoelectric crystal 4...Energy supply device 5, 5"...Processing device 6, 6〃...storage devices 61-63, 61〃-63"...non-volatile memory (EEPROM) 10, 10f, 10"...LED die set 12, 12〃...diffusion sheets 40, 40〃...circuit 50 , 50'·· Digital Signal Processor (DSP) 52, 52〃.·. Voltage Amplifier (VA) 54, 54”·. Analog/Digital Converter (A/D) 71~79...Step 101, 101", 10"'··front planes 102, 102", 102""....right planes 103, 103", 103, ", 103""·.. rear planes 104, 104", 104"". • Left planes 105, 105”····Upper planes 106, 106f, 106”, 106...··· Lower planes 120, 120〃...Other structures 402... Analog switches (AS) 400... Constant current sources Iso 4〇4, 404〃...electric PWM generator 406〃 ... programmable current source (PCS) 10'〃, 10〃〃 ... light-emitting diode 28 M339775

3〃〃...Solar battery 14〃〃..·Light guide plate 31...,32...,33”,····Optical sensor Rl...resistor 29

Claims (1)

M339775 IX. Patent application scope: _ L LED backlight LCD display with attenuation compensation device, including ···, a group of liquid crystal display modules; one set of LED backlights with multiple LED die sets; one set of optical sensing a set of energizing devices that enable the LED chip groups and whose output power is adjustable; a group of health devices having the liquid crystal display module in a predetermined state, the LED die groups at at least one known power a storage device for sensing the optical sensor when the light is turned on; and a set of receiving light from the optical sensing when the one of the LED die groups is illuminated by the known power stored by the storage device Sensing the sensed value of the LED die set, comparing with the pre-stored sensed value in the storage device, and controlling the energy supply device when the sensed value and the pre-stored sensed value reach a predetermined gap A processing device that supplies the electrical energy of the LED die set is changed. The display of claim 1, wherein the optical sensor is a set of photovoltaic crystals. 3. The display of claim 1, wherein the optical sensor is a set of photodiodes. 4. The display of claim 3, wherein the optical sensor is a set of colorimetric photoreceptors. 5. The display of claim 1, wherein the optical sensor is a set of solar cells. The display device of claim 1, wherein the LED backlight panel is provided with a plurality of LEDs directly to the liquid crystal display panel. 7. The display of claim 1, 2, 3, 4 or 5, further comprising a set of voltage amplifiers for amplifying the sensed value of the optical sensor, and a set of converters for converting the voltage amplifier Analog/digital converter for outputting electrical signals. 8. The display of claim 1, 2, 3, 4 or 5, wherein the energy supply device comprises a set of pulse width modulation circuit generators. 9. The display of claim 1, 2, 3, 4 or 5, wherein the energy supply device comprises a set of programmable current sources. 31