TWI418893B - A backlight plate with a series of LED components, a method for manufacturing the same, and a display with the backlight - Google Patents

Description

Backlight board with serial LED assembly, manufacturing method and display with the same

The present invention relates to a backlight panel, and more particularly to an LED backlight panel and a display having the backlight panel by reducing a plurality of light-emitting diodes (hereinafter referred to as LED) components.

The application field of LED has become wider and wider, and has been gradually accepted as the mainstream by the backlight panel and display field, but it is limited by the insufficient brightness of individual LEDs. Therefore, as shown in Fig. 1, after several LED elements 10 are connected in series, a single The DC power source 12 is driven as, for example, a backlight of a notebook computer. The biggest advantage of this technology of serially connecting multiple LEDs is that it simplifies the driving device of the LED, and can provide sufficient electric power to drive multiple LEDs with a larger voltage and a smaller current, and the cost of the power supply is smaller, thereby achieving a lower cost. The purpose of the cost.

However, on the one hand, the size of the display is becoming larger and larger, and the current notebook-size backlight cannot load the large-sized panel; in particular, the individual forward driving voltage range of the serial LED must be limited to a small range. Otherwise, according to the DC power supply of the predetermined circuit design, when flowing through the string of LED components, the driving current will greatly change with the original design, resulting in a large variation in brightness of the entire string of LED components.

However, in the process of manufacturing LED components, first, a wafer is divided into, for example, a batch of 20,000 LED dies, and then packaged into LED components one by one. In the process of wafer fabrication and segmentation, some individual differences may occur. To avoid excessive product performance differences, generally the whole batch of LED dies are tested one by one, and classified according to their forward driving voltage (Bin-Sorting), that is, each LED dies are under a certain fixed driving current, according to crossing the LED The magnitude of the forward driving voltage V _f and the luminance of the two poles of the die are screened. The forward driving voltage required to illuminate the die is too far from the average value. For example, when it exceeds 50 mV, it is classified into another classification, thereby ensuring The forward voltage of the produced grains conforms to a narrow range of intervals; on the other hand, such classification usually requires the elimination of about 10% of the grains, and the cost increases accordingly.

Then in the packaging process of the components, there may be some individual differences due to the various process differences, so that the same batch of LED components of the same batch, as shown in Figure 2, at the same driving current I _f (such as the above current is 20mA) The lower forward driving voltage V _{f is} still a variable, and the range may be in the middle of 3.0V~4.0V, and the V _f value probability distribution P(V _f ) is the inverse clock curve in the figure, the probability The P(V _f ) distribution map is close to the distribution of a normal function Normal Distribution, and its distribution function P(V _f ) can be written as equation (1):

The average forward bias value of the whole batch of LED components is Vav=3.5 Volts, and the standard deviation ΔV distribution of the whole batch of components is about 0.2Volts, that is, about 30% of the components are illuminated by the driving current. At this time, the forward bias is 3.5V away from the average value by more than 0.2V. Before the whole batch of LED components of the same process is shipped, the forward voltage V _f at the same forward current is measured to calculate the probability distribution of the batch of LED components, that is, Where V _f represents the forward bias of each LED element under forward current Is.

In order to make the performance of the product easy to anticipate and control, the fabricated LED components will be classified according to their respective forward bias, luminous brightness and uniformity, and the finer the classification, the higher the classification accuracy requirements, and the cost of classification. The higher the cost of collection and processing, in general, the forward bias bias of 0.1V is often a sub-category. Therefore, under the above 1V difference, all products need to be divided into 10 categories. However, with a forward bias error of 0.1V, generally about 20% of the current error can be caused by the blue or green light of the RGB illumination module, and thus about 20% of the luminance error is generated, and the variation amount is For a backlight that requires high uniformity, there is still a need for improvement.

As mentioned above, since the LED components are detected at a driving current of 20 mA before leaving the factory, the average forward driving voltage is 3.5 V. If not classified, generally when selecting a circuit design in which, for example, 10 white LED elements are serially connected, The required total drive voltage Vcc is designed to be 35V. In practice, however, unless specifically screened, the forward bias actually required to provide a normal drive current tends to deviate from the theoretical average when the number of components is small. Referring to the IV curve of the typical LED component of Figure 3, generally, the higher the V _f value, the larger the current I _f ; and the relationship between the current I _f and the luminance B of the light is as shown in FIG. 4 , after exceeding the basic driving current, The luminance of the light increases substantially linearly with the current value. Once the sum of the forward drive voltages of the 10 LED elements is greater than the theoretical value of 35V and falls, for example, at 38V, the drive current flowing through the entire LED assembly may suddenly drop to 12 mA by the predetermined Vcc=35V. The driving conditions will cause the brightness of the entire string to differ from the original design by 40%, resulting in an unacceptable lack of brightness.

Especially for the current large LCD displays, the backlights required for the backlights are very large. For a 42-inch LCD TV, about 3,000 white LEDs (20 mA) or 3000 RGB LEDs are required. If 30 strings of serially connected LED components are connected in series, the entire backlight plate requires about 100 strings. Even if classified according to the above method, it is not only forced to be classified into more than ten categories, resulting in considerable classification, storage management, and use cost; and once the series of different classifications are used in parallel, the conditions are the same under the same driving voltage. The problem of uneven illumination between LED strings causes a result that some serials are more bleak than other serials. Therefore, for a large-sized display, it is even necessary to consider each LED component of each string of LED components. All belong to the same category.

At present, another conventional technique is shown in FIG. 5, which is driven by a higher DC voltage Vcc, and a current source Is is provided to confirm that the forward current I _f flowing through the series LED assembly is indeed predetermined. Electricity flow. If the LED assembly when the all LED elements 10 are factory V _f distribution in 3.0V ~ 4.0V, the highest voltage requirement need prevail 4V, multiplied by the required driving member 30, and serves more than one DC 120V The voltage source Vcc is added to calculate the voltage drop of the current source Is, so that the actually required Vcc is raised to about 122V. Is provided with a current source current I _f was significantly exceed the highest requirements, to ensure the assembly is in series LED lit as expected. However, using this method has the following disadvantages:

1. The power supply efficiency is low: because the power exceeding the actual demand cannot correspond to driving the LED component to emit higher brightness light, when the actual illumination is equal to the serial LED component according to the voltage classification in the previous example, the previous classification mode will only It takes about 87% of the electricity in this mode;

2. Using a combination of a fixed output current source and a deliberately applied higher voltage source, according to the above calculation, in order to drive 100 strings of LEDs, 100 high-voltage current sources Is must be provided in one display, and the manufacturing cost is dramatized. increase;

3. If the backlight board is composed of RGB three-color crystal grains, the number and cost of the high-voltage resistant current source need to be further increased by three times.

Therefore, the present invention provides a plurality of series-connected LED assemblies, increasing the number thereof, and controlling the number of series connections so as not to distinguish the forward bias when the normal driving current is applied, and still can meet the average level. In terms of eliminating the need for precision classification of LED components, reducing unnecessary classification and management costs; in addition, it is only necessary to use a high-voltage low-current source, and it is not necessary to deliberately select a high-voltage current source that can control the current value, thereby further reducing manufacturing costs, especially With the homogenizing technology possessed by the applicant, the brightness of the light between the various LED components and the particles in the serial LED assembly is uneven, which can be completely obscured and not obvious, greatly reducing the backlight when manufacturing the display. The threshold for the selection of LED components to achieve the dual cost of the lowest cost and highest power efficiency.

The object of the present invention is to provide a backlight board with a series of LED components, which uses a sufficient number of LED elements to be connected in series, so that when the serialized series is driven into a driving current, the driving voltage substantially conforms to the average of the entire batch of LED components. Multiply the value by the number of particles to rule out the need for precise classification of LEDs.

A second object of the present invention is to provide a backlight board with a series of LED components, which uses a sufficient number of LED elements to be connected in series, so that the required driving voltage of the serialized series is in accordance with expectations, thereby eliminating the fixed current value of the high price. The need for a current source.

Another object of the present invention is to provide a display with a series LED assembly, wherein the Ken light plate is connected in series with a plurality of LED elements, so that the driving voltage is substantially matched when the serialized series is driven into the driving current. The average value of the entire batch of LED components is multiplied by the number of particles to eliminate the need for precise classification of LED components; and to make the required driving voltage of the serialized series in line with expectations, thereby eliminating the need for high-priced fixed current value current sources, thereby Amplitude reduces manufacturing costs.

Another object of the present invention is to provide a display with a series of LED components, which utilizes front and rear two reflective sheets to reflect and illuminate the LED components in the backlight panel multiple times between the front and rear reflectors, and only Part of the light is emitted from the front reflector, so that the light source is completely homogenized, further obscuring the uneven illumination of the LED components, thereby allowing the LED element screening threshold to be greatly reduced.

It is still another object of the present invention to provide a backlight manufacturing method with a tandem LED assembly that eliminates the need for precise classification of LED components, thereby greatly reducing manufacturing costs.

A further object of the present invention is to provide a front-end and rear-side reflective sheet, so that the LEDs of the tandem LED assembly are reflected and homogenized multiple times between the front and rear reflectors to cover the LEDs of the tandem LED assembly with uneven illumination. The backlighting method of the component.

A backlight board with a serial LED assembly, a method for manufacturing the same, and a display having the same, mainly comprising a set of energy supply devices, at least one set of serial LED assemblies and a set of liquid crystal modules, wherein the energy supply device Providing power to the serial LED assembly and the liquid crystal module, the serial LED assembly is powered by the power supply device, and the serial LED assembly is composed of a plurality of LED elements connected in series, through the serial connection The method can achieve the characteristics of current sharing of the LED components connected in series, and the liquid crystal module is powered by the power supply provided by the energy supply device, and is displayed as a liquid crystal mode by being backlit by the LED assembly. a backlight source; and the backlight board can be used together with a group of light-sharing devices, the light-sharing device mainly comprises a light-shading sheet, a front reflection member and a rear reflection member, wherein the front reflection member is disposed on the light-shading sheet and Between the LED components is arranged in series, and the back reflector is disposed away from the side of the light homogenizer, wherein the reflectivity of the rear reflector is close to complete reflection, and the reflectivity of the front reflector is higher than the transmittance but less than the rear Reflector reflectivity The light homogenizing apparatus so through different reflectance before and after the reflection member of the reflection member may be connected in series to increase the illumination of the LED light source assembly, and the purpose of effective utilization of electric power and uniform light source.

FIG. 6 is a block diagram showing a structure of a backlight board having a series LED assembly, which mainly includes: a backlight board 30 and a liquid crystal module 36; and the backlight board 30 includes an energy supply device 32 and at least two sets of strings connected in parallel with each other. The LED assembly 34 is connected.

The energy-providing device 32 is configured to provide, for example, two strings of LEDs 34 and LCD modules 36 connected in parallel with each other; and as shown in FIG. 7, each of the series LED assemblies 34 includes a plurality of LEDs connected in series with each other. The components 340, and the light emitting sides of the LED elements 340 are all disposed in the same direction; the liquid crystal module 36 is disposed corresponding to at least two sets of the LED assemblies 34, and is illuminated by the serial LED assemblies 34 in a backlight manner.

The IV curve of a typical LED component generally has a higher V _f value and a larger current I _f , wherein for the same LED component, the relationship between the current I _f and the luminance B is higher than the basic driving current, and the luminance varies with the current. The value increases roughly linearly. However, with the slight difference in various conditions in the process, even the LED components manufactured by the same company, even the components encapsulated by the LED die on the same wafer, have the IV curves of each. difference. Therefore, if N LED elements manufactured in the same batch are connected in series, the total forward bias of the total series under the forward current I _f is V _f (T) = V _f (1) + V _f (2) + ‧‧‧‧V _f (N), as shown in Figure 8, according to the mathematical theory of Normal Distribution, the probability distribution function P(V _fT ) of the forward bias V _fT after series connection can be written as:

Where V _avT =N×Va......(3)

The LED component distribution of the above example is taken as an example. If 100 LED elements are connected in series, the theoretical value of the total forward bias voltage V _fT is (V _fT ) av = 100 × 3.5 = 350 Volts as shown in the formula (3). And its standard deviation: Compared with the probability distribution diagram P(V _f ) shown in Figure 2, the average forward bias of individual LED components is 3.5V, and the standard deviation is 0.2V. It can be found that the forward polarization of the entire LED assembly after series connection The theoretical pressure value (V _fT ) _av =350Volts is still the theoretical value of the individual components multiplied by the number of series components; but relatively, the standard deviation of the forward bias of the LED components after series connection is ΔV _T =2.0Volts, which is significantly better than 0.2. The value of V×100 is reduced, that is, although the tandem LED assembly disclosed in the present invention does not pass through the classification process of the LED element before manufacture, the sum of the forward bias is still smaller than the original single. The distribution ratio at the time is significantly narrowed. It can be concluded from the above formula that if there are N LED elements connected in series, the distribution range can be reduced to the original range. Times, that is, serially connecting 100 unclassified LED elements, the forward bias value of the serial component can be reduced to one tenth of the original theoretical value and the number of serial numbers. For example, in the first preferred embodiment, when 400 LED elements are connected in series, the distribution range of V _f can be reduced to the original one. .

Even with four standard deviations as the boundary, the minimum value of V _fT is about 350-(4×2.0)=342Volts, and the maximum value is about 350+(4×2.0)=358Volts, forward bias between multiple strings of LED components. The gap is at most 358V-342V=16V, which is still smaller than the dispersion of the original unclassified single LED component; however, four times the standard deviation means 99% of all tandem LED components produced. All of the above are in this range, especially when the number of LED elements in series is increased, the degree of positive phase bias concentration of the entire string of LED components can be more pronounced.

Using the above principle, the second preferred embodiment of the present invention will take a 42-inch LCD TV backlight as an example to calculate the actual situation: here, the brightness of the backlight panel is 6000 cd/m ² , and the area of the backlight panel It is about 0.54m ² , so the total brightness of the required LED is 3200cd. When the white LED component is at the forward current I _f =20mA, the average brightness of each LED is 1cd, then the number of white LEDs required by the backlight is It is 3,200.

Considering the general high voltage and low current power supply cost lower voltage and high current cost, so the same 400Watls power supply, if 5Volts, 80A power supply cost will be much higher than 1000Volts, 0.4A power supply cost. Since the current high-voltage low-current power supply has been widely used in the backlight board of the original CCFL cold cathode tube. Therefore, in the present invention, the inverter of a general cold cathode tube is also used as a power source, but the present invention does not limit the use of other power sources. The CCFL Inverter is a high-voltage, high-frequency AC power supply, so a bridge rectifier and filter capacitor must be added to the output to become a high-voltage DC power supply. However, other general high-voltage DC power supplies use a DC-DC-Converter circuit to convert a low-voltage DC power supply into a high-voltage DC using a Buck. Converter circuit.

In this example, it needs to use 3200 white LEDs. Through the principle described above, more LEDs can be used in series, which can reduce the variation range of the total forward bias. Therefore, as shown in Figure 9 in this example, For example, 400 LED elements are connected in series, wherein each string of LED components has 400 LED elements, and the light source in the backlight board is composed of 8 strings of LED components such as ST1, ST2, ‧‧‧‧ST8.

If the average forward voltage (at current I _f = 20 mA) of each single white LED component is 3.5 Volts, and the forward bias distribution of a single LED ranges from 3.0 Volts to 4.0 Volts, then 400 LEDs are connected in series. After the LED assembly, the total forward voltage requirement for each component is 1400 Volts, and the total forward bias distribution of the tandem LED assembly is shown in Figure 10. It will be limited to 1390 Volts~1410 Volts.

As shown in FIG. 11, the anodes of the eight sets of LED assemblies 34' are completely connected to the power supply Vcc having a voltage of 1400 Volts, and the ground terminals of the serially connected LED assemblies 34' are also connected to a 10 Ω resistor Rs. The working current I _T is used to support the voltage Vs and the regulated voltage of the power supply Vcc. Since the DC power supply Vcc is selected as 1400 Volts, the possible distribution range is less than the ideal total forward bias value, and the error is only within 1% because the difference in forward voltage between the LED strings of each string is small. Even if the eight strings of series LED assemblies 34' are used in full parallel, only a single energizing device is enabled, applying the same voltage Vcc to the series LED assemblies 34', and the difference in luminous intensity of each of the series LED assemblies 34' is also Extremely limited and cannot be easily observed.

Since the total forward bias voltage value of each string of LED components V _T (I)=V ₁ (I)+V ₂ (I)+----V ₄₀₀ (I), the IV curves of the LED elements are all The difference is such that the actual total forward bias of each string of LED components is different when the drive current is fixed. Conversely, if the common forward voltage Vcc is selected to be fixed at 1400 Volts, the relationship between the total forward bias voltage V _T (I) of each string of LED components and the current I is as shown in FIG.

Wherein, when the fixed current is 20mA, the total bias voltage needs to be 1410V of the string of LED components, and the forward current I _f at Vcc=1400V will be slightly estimated as Relatively, the forward bias current I _f at Vcc=1400V is the set of LED components with a total bias of 1390V at a forward current of 20mA. .

It can be seen that, in accordance with the manufacturing method of the present invention, even in the first step, the LED elements 340' are not connected in series without being carefully selected, and when the number of serially connected LED elements is sufficiently large, at least the second step will be composed. two sets of series LED assembly 34 'in parallel to the power supply Vcc enabling a single set, each of the series LED assembly 34' are very close to the original drive current over a predetermined drive current I _f = 20mA, and may determine the total flow through Rs The operating current is still quite close to the ideal value of 160 mA (20 mA x 8), and the difference in forward current between the series of LED components 34' is also limited to 5%. Further, since the brightness of the LED is approximately proportional to the current, the average brightness difference of each series LED assembly 34' is also within 5%.

Further, if the brightness of the backlight is to be adjusted, the Vcc voltage can be adjusted to, for example, 1300 Volts (3.25 V x 400 LEDs), and the forward current of each string of LED components 34' is connected in series. Using the relationship between the luminance of the light emission and the current I _v -I _{f in} FIG. 13, it can be seen that the luminance B of the light is about 75% of that of the aforementioned 20 mA. Therefore, as long as the voltage of Vcc is modulated, the brightness of the LEDs 34' of the series can be controlled. Since the eight strings of LED components are driven by the same forward current, the forward bias of each other may be only about 1%; therefore, when the same voltage is applied in parallel, the individual forward current error will be limited to 5%. .

As shown in the previous embodiment, when a string of LED components is actually connected in series with 400 LED elements, and the forward voltage across each LED element is about 3.5V, the potential difference across the end of a string of LED components will reach 1400V; Once the engineer of the design circuit does not check, the whole series of LED components are reversely folded into a U-shaped distribution design. When the distance between the two ends is insufficient, the voltage at both ends of the LED component is directly short-circuited and jumped.

In order to improve safety, the present invention has a second preferred embodiment of a backlight board with a series of LED components. The LED distribution of the backlight panel will be arranged as shown in FIG. 14 , and ST1 is disposed at the uppermost portion as shown in the figure, and Steps ST2, ... ST8 are sequentially set up and down, and 8 strings of LED components ST1, ST2, ... ST8 are arranged in a reverse order of eighteen times for each string of LED components, so that each refraction arrangement will be only connected in series of 5 LED components. Therefore, the potential difference is only 35V between the ends of the first array and the second array. The serial connection using this method can reduce the voltage difference between the LEDs and ensure the safety of the wiring on the PCB.

Of course, as can be easily understood by those skilled in the art, although the above embodiments are all based on white LED components, LED backlights constructed by using RGB three-color LED components are indispensable, only R, G, and B. The positive bias voltages of the color LED elements are not the same, so the LED elements of each color must be self-contained in multiple strings and driven at different voltages according to their respective colors. For example, a 42-inch backlight in the above example requires 3200 sets of R, G, and B LED components, respectively. If each 400 LED elements are connected in series to form a string of monochromatic LED components, each color LED component needs 8 String, and the same color of 8 series of LEDs can use the same high-voltage DC power supply, so three different voltage power supplies are needed. When the color temperature needs to be adjusted, the three supply voltages of V _ccR , V _ccG and V _ccB can also be adjusted. The size, you can individually adjust the different supply currents of red, green and blue, thus producing the required brightness ratio to achieve any color temperature required.

Further discussion, due to the difference in the process of LED components, although the LED components are driven by the same current, the output brightness of the LED components may reach ±20%. If the most economical structure is to be achieved and the need for classification screening is reduced, such brightness differences must be uniformized to avoid viewers immediately discovering differences in brightness between such LED elements.

Therefore, when the backlight panel of the present invention is formed into a display, a preferred embodiment of the display of the present invention is as shown in FIG. 15 , after the backlight panel is completed, a set of light-collecting devices 38 ′ are disposed at the corresponding backlight panel. The light homogenizing device 38' of the present embodiment includes two front and rear reflecting members having different reflectances, which are exemplified as front and rear reflecting sheets 382', 384' and reflectance of the rear reflecting sheet 384'. Planned for 100% complete reflection, only the front reflector 382' is partially transmissive. Thereby, the light emitted by the LED element 340' is substantially reflected whether it is irradiated to the front reflection sheet 382' or the rear reflection sheet 384', and is continuously moved back and forth between the two reflection sheets, and finally to the front reflection sheet 382'. After being permeable, it is homogenized by the homogenizer 386', and finally irradiated to the liquid crystal module 36'. Thus, a highly reflective partially transmissive sheet is used to form a multi-reflective optical resonant cavity with the bottomed total reflection sheet to increase the uniformity of the line of illumination of the series LED assembly 34'.

With this technique, if 10% transmission and 90% reflection of Partial Transmission Films are used as the material of the front reflector, the uniformity of the LED elements can be increased by 10 times according to the experimental results. That is to say, even if the brightness of the original LED elements is ±20%, after the structure is homogenized, the non-uniformity will only remain at most ±2%; moreover, according to the foregoing analysis of the present case, each series of LEDs The difference in luminance between components is less than 5%. Thereby, the advantage of not requiring classification of the LED elements is thoroughly exerted to the utmost, and the problem of uneven brightness of the luminance of the unclassified LED elements is concealed to the point where it is difficult to observe.

As can be seen from the above description, by using a plurality of LED elements in series, not only the difference in forward bias between the series of LED components can be reduced, so that the multi-string LED components of the same function can be driven in parallel and driven by a set of power sources. Moreover, the threshold for the difference in forward voltage and brightness of each LED element can be greatly reduced, and the manufacturing cost is greatly reduced, thereby making a very economical backlight. Of course, the number of serially connected LEDs can be easily understood by those skilled in the art. As long as, for example, 36 can be achieved, the deviation of the total forward bias voltage of the serially connected LED components can be made smaller than the deviation of the LED components. The product of the total number of components is reduced by a factor of six, such that, for example, a 12-inch panel can be connected in parallel, for example, with two sets of low cost series LED assemblies.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications according to the scope of the present invention and the description of the invention are still It is within the scope of the patent of the present invention.

10. . . LED component

12. . . DC power supply

30. . . Backlight

32. . . Energy supply device

34, 34’. . . Serial LED assembly

340, 340’. . . LED component

36, 36’. . . LCD module

38’. . . Homogenizer

382’. . . Front reflector

384’. . . Back reflection sheet

386’. . . Uniform film

Figure 1 is a schematic diagram showing the illumination of several serially connected LED elements driven by a single DC power supply;

2 is a probability distribution diagram of a forward driving voltage V _f value of a conventional LED element at a driving current of 20 mA;

Figure 3 is a graph showing the I-V relationship of a general LED element;

Figure 4 is a graph showing the relationship between the current I _f of the general LED element and the illuminance brightness B;

Figure 5 is a schematic diagram of the conventional use of the current source Is to illuminate the series connected LEDs, indicating that the supplied voltage Vcc needs to exceed the maximum required voltage of a single LED multiplied by the number of LEDs connected in series;

6 is a block diagram showing the structure of a first preferred embodiment of a backlight panel having a series LED assembly according to the present invention;

Figure 7 is a schematic structural view of the embodiment of Figure 6;

Figure 8 is a graph showing the probability distribution of the total forward bias voltage V _fT of the tandem LED assembly used in the driving current of 20 mA in the embodiment of Figure 6;

9 is a schematic view showing a setting manner of a plurality of sets of serial LED assemblies on a backlight panel of the embodiment of FIG. 6;

10 is a distribution diagram of a total forward bias I-V curve of each serial LED assembly of FIG. 6 at a driving current of 20 mA;

11 is a schematic circuit diagram of a backlight panel of the embodiment of FIG. 6 , illustrating a relationship between the power supply device and the circuit components of the serially connected LED components;

Figure 12 is a graph showing the relationship between the flow current I and the total forward bias voltage V _fT when the same forward voltage Vcc is applied to the series LED components of Figure 11;

13 is a graph showing the relationship between the luminance of the light and the current Iv-I _{f in the} embodiment of FIG. 6, illustrating a control mode for adjusting the brightness of the backlight;

FIG. 14 is a schematic diagram showing the reverse folding arrangement of the serially connected LED components in the second preferred embodiment of the backlight panel having the serial LED assembly of the present invention; and

Figure 15 is a schematic view showing the structure of the first preferred embodiment of the display of the present invention, illustrating the structural relationship between the light homogenizing device and the backlight.

34’. . . Serial LED assembly

340’. . . LED component

Claims (12)

A backlight board having a series LED assembly, comprising: a set of energy supply devices; and at least two sets of tandem LED assemblies connected in parallel to each other, collectively enabled to emit light by the energy supply device, and respectively comprising a plurality of LED elements connected in series with each other The number of the series connected LEDs is such that when the at least two sets of tandem LED assemblies are illuminated, the entire string of enable voltages of the at least two sets of tandem LED assemblies is subtracted from the LEDs in the assembly The difference between the average enable voltage of the component and the number of LEDs in the component is less than one-sixth of the statistical standard deviation of the individual enable voltages of the LED components in the component and the number of the LED components in the component; Thereby, the individual differences of the LED elements affect the degree of influence of the enabling voltage provided by the energy supply device by one-sixth; the above-mentioned text is |V _fT -Va×N|<(ΔV ×N)×K, K≦(1/6), wherein V _fT is the entire string of enabling voltages of the above (at least two sets of LED components in series), and the average enabling voltage of the V _a LED elements is The number of N-series LEDs, K is the statistical standard deviation of the individual enable voltages of the LED components multiplied by the number of such LED components in the component The rate of the product. The backlight of claim 1, wherein the difference is less than one tenth of a product of the standard deviation and the number of the LED elements in the component. The backlight of claim 1, wherein the light-emitting sides of the LED elements of the at least two sets of LED components are disposed in the same direction. For example, the backlight panel of claim 1, 2 or 3 includes a set of light homogenizing devices. The backlight unit of claim 4, wherein the group of light homogenizing devices comprises: a light homogenizing sheet; a set of front reflecting members respectively disposed between the light homogenizing sheet and the at least two sets of tandem LED assemblies, and setting The at least two sets of LED components are separated from the rear reflector of the light homogenizer side; wherein the reflectance of the rear reflector is near complete reflection, and the reflectance of the front reflector is higher than the transmittance but less than the rear Reflector reflectivity. A display having a backlight assembly of a series LED assembly, comprising: a set of backlights having a series of LED components, comprising: a set of energizing devices; and at least two groups comprising a plurality of LEDs connected in series with each other and being caused by the energizing device An illuminable series LED component, the number of the series LEDs being such that when the at least two sets of series LED components are illuminated, the enabling voltage of the at least two sets of series LED components is subtracted from the component The difference between the LED average enable voltage and the number of LEDs in the component is less than one sixth of the statistical standard deviation of the individual enable voltages of the LEDs in the at least two components and the number of LEDs in the component; Thereby, the degree of influence of the individual differences of the LEDs on the enabling voltage provided by the energizing device is reduced by one sixth, and the above character is |V _fT -Va×N|<(ΔV× N) × K, K ≦ (1/6), wherein V _fT is the entire string of enabling voltages of the above (at least two sets of LED components in series), V _a is the average enabling voltage of the LED elements, N The number of LEDs, K is the number of times the statistical standard deviation of the individual enable voltages of the LED components is multiplied by the number of LED components in the component. Rate; and a set of liquid crystal modules corresponding to at least two sets of LED components arranged in series. The display of claim 6, wherein the at least two sets of LED components are arranged to face the liquid crystal module. The display of claim 6, wherein the difference is less than one tenth of a product of the standard deviation and the number of the LEDs in the component. The display of claim 6, wherein the backlight further comprises a set of light homogenizing means. The display device of claim 9, wherein the group of light homogenizing devices comprises: a light homogenizing sheet; a set of front reflecting members respectively disposed between the light homogenizing sheet and the at least two sets of tandem LED assemblies, and The at least two sets of LED components are away from the rear reflector of the light homogenizer side; wherein the reflectance of the rear reflector is near complete reflection, and the reflectance of the front reflector is higher than The penetration rate is less than the reflectance of the rear reflector. A method of fabricating a backlight having a series LED assembly, comprising the steps of: a) planning at least two sets of tandem LED assemblies each comprising a plurality of LED elements connected in series; and b) providing an energy supply device for parallel connection Capable and illuminating the at least two sets of tandem LED assemblies; wherein the number of the series connected LEDs is such that when the at least one set of tandem LED assemblies is illuminated, the at least two sets of tandem LED assemblies are any The difference between the entire string of enable voltages minus the product of the average enable voltage of the LED elements in the component and the number of LEDs in the component is less than the statistical standard deviation of the individual enable voltages of the LED components in the component. One-sixth of the number of the number of LED elements in the component; thereby, the individual differences of the LED components affect the degree of influence of the enabling voltage provided by the energy supply device by one-sixth; The text is V _fT -V _a ×N|<(ΔV×N)×K, K≦(1/6), where V _fT is the whole series of the above (at least two sets of LED components in series) enable voltage, V _a mean-based LED element enable voltage, the number of N-based LED, K is a unique LED element voltage can The standard deviation of the count number of LED elements assembly such product magnification. The method for manufacturing a backlight board having a serially connected LED assembly according to claim 11 further includes a step c) of setting a group of light homogenizing devices, wherein the group of light homogenizing devices comprises: a light homogenizing sheet; a front reflection member between the light-shading sheet and the at least two sets of LED components, and a rear reflection member disposed on the side of the at least two sets of LED assembly away from the light-shading sheet; wherein the reflectance of the rear reflection member is nearly complete Reflected, and the reflectance of the front reflector is higher than its transmittance but less than the reflectance of the rear reflector.