KR20020033718A - The patten design method of the light guide panel for the back light - Google Patents

Abstract

PURPOSE: A method of designing a light guiding plate pattern is provided to efficiently and rapidly design a light guiding plate having close relation with the performance of a back light depends with accuracy. CONSTITUTION: The standard of a light guiding plate is set. The light guiding plate is divided into regions. The same light-reflecting structure is set at each of the divided regions and reflectivity of each region is determined. The surface luminance of the light guiding plate on which the light-reflecting structure is placed is measured. A light reflectivity according to the shape of the light-reflecting structure is decided. A pattern structure of the light-reflecting structure is determined based on the light reflectivity and reflectivity of each of divided regions. A pattern is formed according to the determined pattern structure to manufacture a light guiding plate.

Description

The patten design method of the light guide panel for the back light}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate pattern design method used as a backlight for a liquid crystal display (LCD) or an image display device.

In general, display devices are one of the key electronic components in the information society. Among them, a light guide plate widely used as a back light of an image display device such as a liquid crystal display device is one side of a plate made of a transparent parallel flat plate or a wedge-shaped flat plate, and reflects the light generated from the light source to the entire surface of the light guide plate evenly. It is in charge of the midrange that is replacing the display element represented by cathode ray tube (CRT) with liquid crystal display (LCD).

In the backlight industry, although this part is an important part to be an essential part of the LCD device, development of new technology, which is qualitatively focused on quantitative development, has not made much progress.

The core of the technology related to the backlight is the design technology of the light guide plate. Until now, Korean companies have used trial and error methods based on their own experience or depend on foreign technology. Therefore, it takes a lot of time to develop a new product, so there is a problem that it is difficult to realize a competitive product development because the ability to respond to the launch of the new product is much lower. This is because the pattern is developed by experience without a kind of formula for the pattern design of the light reflection structure installed in the light guide plate.

In conclusion, the design of the light guide plate is the most important task in the development of the backlight. The performance of this light guide plate is largely due to the difference in performance of the backlight between manufacturers and products.

Accordingly, an object of the present invention is to provide a light guide plate pattern design formula used as a backlight of a liquid crystal display (LCD) and the like, and a light guide plate pattern design method using the same.

Selecting the size of the light guide plate to achieve the above object, setting the area division in the light guide plate in which the standard is selected, installing the same light reflecting structure in each divided area, and determining the reflectance for each area of the light guide plate; Measuring the surface luminance of the light guide plate provided with the light reflection structure, determining the light reflectance according to the shape of the light reflection structure, and determining the light reflectance according to the shape of the light reflection structure and reflectance of each region of the light guide plate. Determining the pattern structure of the reflective structure, manufacturing a light guide plate prototype by processing a pattern for each region according to the determined pattern structure, measuring luminance uniformity for each region in the light guide plate prototype manufacturing step, and luminance unevenness in the brightness uniformity measurement step Compensation of the pattern for the part to complete the light guide plate pattern to the new product (light guide plate) The design technology theory to find the optimal manufacturing conditions that can realize the best performance while minimizing the development period for the system is established, and the new model LGP can be manufactured based on this result.

1 is a schematic flowchart of the present invention.

2: Surface luminance characteristics of a light guide plate having V grooves having equal intervals in the present invention

3: Comparison of surface luminance characteristics of a light guide plate having V grooves having equal intervals in the present invention

4: Luminance characteristics of the 15 "size light guide plate manufactured by the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart according to a method of designing a light guide plate pattern according to the present invention, including selecting a light guide plate size, setting a region division in the light guide plate, installing a light reflecting structure in each area, and measuring the surface luminance of the light guide plate. The light reflectance determining step according to the shape of the light reflecting structure, the reflectance determining step for each light guide plate region, the pattern structure determination step for the light reflecting structure according to the reflectance determined for each region, the pattern processing step for each region, the light guide plate manufacturing step And a luminance uniformity measurement step for each region, a pattern correction step for the luminance non-uniformity portion, and a light guide plate pattern completion step.

In the present invention, in determining the reflectance according to the light reflector structure, for example, the reflectance according to the depth of the V groove or the U groove, the scattering printing method, the special light reflecting structure such as the reflectance according to the printing area, the standard time signal or the amorphous time signal method And reflectance according to the size of the light guide plate. For example, the light guide plate may be manufactured in a mold manufacturing method, a printing method or a method of directly processing a pattern such as V-cutting or U-cutting.

And as a light reflection structure, it is 1). Light reflection structure by scattering printing method, 2). Light reflection structure by V groove or U groove method, 3). It includes all types of light reflecting structures, such as orthopedic or amorphous time signal.

The size (standard) of the light guide plate varies greatly depending on the size of the LCD to be employed. In order to develop a light guide plate for backlights required for LCDs of different sizes, it is very time-consuming to solve the pattern of the light guide plate by repeated experiences, and it is necessary to respond quickly to new product launches. Will fall.

The light guide plate design procedure for obtaining a light reflection pattern capable of obtaining a fast pattern and obtaining a desired uniform luminance while solving such a problem is as follows.

First, a light guide plate having a predetermined size is selected. In designing the light guide plate according to the present invention, the size of the light guide plate, that is, the size of the horizontal length or the vertical length can be applied without any limitation.

When the standard of the light guide plate is selected, the position of the light source is set from the four corners of the light guide plate, and light is incident therefrom and totally reflected inside the light guide plate, and the incident light is reflected by the light reflecting structure installed on the back of the light guide plate. It is supposed to have a function as a light guide plate.

Next, the length from one end face to which the light source is incident to the other end face of the light guide plate is uniformly divided into N regions. At this time, the length of each region is equally spaced.

The length of the divided region is such that at least one light reflecting structure having a minimum reflectance can be provided.

After setting the equal intervals in the light guide plate, a light reflection structure is provided for each area. In this case, the light reflection structure is formed by directly injecting or forming a light reflection structure, a V-shaped or U-groove groove, or a square or circular groove formed on a light guide plate by forming a material having high light reflection efficiency. It consists of a special light reflection structure, such as a light reflection structure, an orbital time signal type, or an amorphous time signal type.

The next step is to obtain the light reflectance of the light reflection structure formed on the light guide plate, and the shape of the light reflection structure formed for each region is the same.

After assembling in the backlight state using the light guide plate manufactured in this step, the luminance on the surface of the light guide plate is measured.

FIG. 2 is a luminance characteristic diagram of luminance of a light guide plate having a size of 15 inches, and Table 1 below is a comparison chart of surface luminances of a light guide plate having V grooves having equal intervals.

(Table 1) A surface luminance comparison table of light guide plates with V grooves at equal intervals.

Area (n) Brightness (cd / ㎡) Measuring conditions 10 681 . Light guide plate thickness 4.5mm. Applicable voltage 9.1V. Tube current 244 mA. Measuring distance 70cm 20 692 30 654 40 605 50 533 60 494 70 433 80 391 90 342 100 294 110 269 120 242 130 219 140 185 150 180 160 158 170 145 180 132 190 124 200 118

At the incidence end of the light guide plate, the luminance becomes higher and the light intensity decreases gradually. This is because the light reflection structures formed in each region are all the same structure and the light reflectance is constant. Therefore, if the light I1 reflected in the first area is Io,

I₁ = IoR ----------------------------------------------- ----- Formula (1)

And the reflected light I2 in the second region

I₂ = Io (1-R) R ----------------------------------------- ------- Formula (2)

Therefore, the reflected light In in any n-th region is

In = Io (1-R) n- ¹ R -------------------------------------- ------- Formula (3)

Becomes Obtaining the reflectance R using Equation (3) from the graph of FIG. 2 is shown in Table 2 below.

(Table 2) Comparative table of surface luminance of light guide plate with equally spaced v grooves.

Area (n) Luminance (cd / ㎡) Calculated luminance (cd / ㎡) 10 681 828 20 692 724 30 654 665 40 605 595 50 533 533 60 494 477 70 433 428 80 391 383 90 342 343 100 294 307 110 269 275 120 242 246 130 219 221 140 185 198 150 180 177 160 158 158 170 145 142 180 132 127 190 124 114 200 118 102

When the reflectance is obtained in FIG. 2, R = 1.097%.

Table 3 below is a comparison table of luminance measurements for a 15 "size light guide plate according to the present invention. FIG. 3 is a graph comparing theoretical values by applying measured values and reflectance R = 1.097%. We can see that we get a good match except for the points.

(Table 3) Comparison table of luminance measurements for a 15 "size light guide plate.

Area (n) Surface luminance (cd / ㎡) Area (m) Surface luminance (cd / ㎡) 10 1570 110 1536 20 1540 120 1534 30 1535 130 1532 40 1530 140 1538 50 1535 150 1537 60 1534 160 1540 70 1538 170 1540 80 1538 180 1542 90 1535 190 1545 100 1537 200 1550 Average 1539.3

In the case of manufacturing a light guide plate by applying a light reflector by a printing method, the reflectance according to the size of the printed light reflector can be obtained through Equation (3). When the light reflector is formed on the light guide plate or the light reflector is inscribed on the mold, the light reflectance according to the processing degree of the light reflector can be obtained.

In the next step, the reflectance of each region is determined to obtain the same luminance on the light guide plate surface. Since the LGP is divided into N regions, the amount of light derived from each region must be uniform in order to obtain optical characteristics of uniform luminance on the surface of the LGP. If the amount of light derived from each region satisfies Io / N, the light guide plate may be the most ideal type.

The reflectance R₁ in the first region is

IoR₁ = Io / N --------------------------------------------- ----- Formula (4)

From R1 = 1 / (N-O) can be obtained.

In the second area

(Io-IoR1) R₂ = Io / N ---------------------------------------- ---- Formula (5)

From R2 = 1 / (N-1) can be obtained.

Therefore, in the nth region

Rn = 1 / (N- (n-1)) ------------------------------------- --------- Formula (6)

Since the value of can be obtained, the reflectance for each region can be obtained using Equation (6).

The next step is to determine the structure of the light reflection structure according to the reflectance obtained for each area.

In the case of the printing method, the print area corresponding to the reflectance R1 in the first area is determined, and then the print area for each area is determined. In the pattern to be printed, the print pattern may be determined to have a smaller area than the end of the light guide plate on which the light is incident on the light-receiving plate. The specific size of the area is determined according to the result of equation (6).

In the case of forming the V-groove, the depth of the V-groove will be shallow at the side where light is incident, and the end portion of the light guide plate through which the light will reach will be deeply formed. Alternatively, if the depth of the groove is constantly processed, the reflectance can be adjusted by a method of adjusting the spacing of the V groove, so that adjusting the V groove spacing according to the reflectance for each region is one means of achieving the object of the present invention. This can be

The following describes an example of obtaining uniform luminance characteristics for each region by adjusting the V groove spacing.

If the reflectance R of the V groove having an arbitrary groove depth is 0.01, the reflectance R1 in the region where n is 1 should have a reflectance smaller than R, that is, smaller than 0.01, in order to obtain uniform luminance. If the required reflectance is 0.001, it is 1/10 of R, so it is approximated to form 1/10 V groove in this area. This method is not practical, so instead, 1 V in the area 10 times the length of the unit area. By forming a groove, an approximate effect can be achieved.

If the pattern is designed in this way, the distance between the first groove and the groove is R / R1 · L / N, which is the product of L / N times the ratio R / R1 of the two reflectances. Therefore, the interval between the nth groove and the groove is R / Rn · L / N.

Since the entire length of the light guide plate is ℓ

R / R1L / N + R / R2L / N + R / RNL / N = L Equation (7)

Satisfies the relation Equation (7) can again be established as follows.

R / R1 · / N + R / R22 / N ++ R / RN // N = ℓ

R · L / N (1 / R1 + 1 / R2 + ... + 1 / RN)

= R · L / N ((N-0) + (N-1) + (N-2) + ...) + (N- (N-1)))

= R · L / N (N · N- (N (N-1) / 2)

= Rl / N- (N-1) / 2)

= R · L (N + 1) / 2

= ℓ

∴ R (N + 1) / 2 = 1 -------------------------------------- -------- Formula (8)

In Equation (8), when the reflectance R is large, the number N of the total line must be small, and if the reflectance R is small, the number N of the total line must be large.

The length of each area by pattern design is given as follows.

① Length of the first area ℓ1 = R / R1 · ℓ / N

② Length 2nd area ℓ2 = R / R2 · ℓ / N

③ Length of the third area ℓ3 = R / R3 · ℓ / N

.

.

.

Length of Nth region ℓN = R / RN ・ ℓ / N --------------------------- Equation (9)

4 shows the results of an example of applying the light guide plate pattern design using the V-groove method.

The surface luminance was measured after the pattern was processed by adjusting the V-groove spacing using the reflectance designed for each region.

Overall, the uniformity of brightness was 97.5%, and the theoretical design and the pattern processing results accordingly match very well.

It is possible to obtain the reflectance using the design formula provided by the present invention simply by hand, but another object of the present invention is to use the minimum time for designing the pattern. It is desirable to program and use the light guide plate pattern design.

In conclusion, the design of the light guide plate is the most important task in the development of the backlight. The performance of this light guide plate is largely due to the difference in performance of the backlight between manufacturers and products.

The present invention as described above is not limited to the present embodiment and the accompanying drawings, various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the present invention, which is usually in the art It is self-evident for those who have knowledge.

As described above, the present invention has the effect of providing a formula for precisely and quickly designing a light guide plate in order to design the light guide plate that greatly influences the performance of the backlight efficiently and with the best performance.

In addition, according to the design formula of the present invention it was possible to manufacture a backlight having a characteristic of the luminance uniformity of 97.5% in the case of 15-inch light guide plate.

When the light guide plate of the new model is developed using the theory established in the present invention, the development can be efficiently carried out, and the design value of the optimum condition can be obtained.

Claims (6)

Selecting a size of the light guide plate, setting a region division in the light guide plate in which the standard is selected, installing the same light reflecting structure in each divided region, determining a reflectance for each region of the light guide plate, and installing the light reflecting structure Measuring the surface luminance of the light guide plate, determining the light reflectance according to the shape of the light reflection structure, and determining the pattern structure of the light reflection structure according to the light reflectance according to the shape of the light reflection structure and the reflectance of each region of the light guide plate. And manufacturing a light guide plate prototype by processing a pattern for each area according to the determined pattern structure. The method according to claim 1; A method of designing a light guide plate pattern, the method comprising: measuring luminance uniformity for each region in a light guide plate prototype manufacturing step; and completing a light guide plate pattern by correcting a pattern for a luminance non-uniformity portion in a brightness uniformity measurement step. The method according to claim 1 or 2; As the light reflection structure that can be determined in the pattern structure determination step of the light reflection structure, the light reflection structure by the scattering printing method, the light reflection structure by the V groove or the U groove method, the light reflection structure of the orthogonal telegram method, the amorphous time signal method The light guide plate pattern design method, characterized in that one of the light reflection structure. The method according to claim 1 or 2; The light guide plate pattern design method, characterized in that the pattern manufacturing method in the light guide plate prototype manufacturing step is one of a mold manufacturing method, printing method, V-cutting method, U-cutting method. The method according to claim 1 or 2; In the step of determining the light reflectance according to the shape of the light reflecting structure, the reflectance R 에서 의 in the first region obtains R1 = 1 / (NO) from IoR₁ = Io / N, and (Io-IoR1) R₂ = Io in the second region. R2 = 1 / (N-1) is obtained from / N and Rn = 1 / (N- (n-1)) in the nth region to obtain reflectivity for each region. Design method. The method according to claim 1 or 2; A method of designing a light guide plate pattern comprising forming one V-groove in an area 10 times the length of a unit area in the step of setting a region division in the light guide plate to achieve an approximate effect.