KR200287371Y1 - The light guide plate for the back light - Google Patents

Abstract

The present invention relates to an optimal light guide plate having shortened development time while obtaining uniform luminance characteristics by forming a light reflection structure on the light guide plate using a formalized formula.

To this end, the present invention is to form a light reflecting structure at equal intervals, the light reflectance (R) by the light reflecting structure and the reflectance (R _n ) of the n-th unit region divided by the light reflecting structure of the n-th unit region After determining the correction pattern interval (f _n ) for the pattern interval (d _n ) and the luminance nonuniformity unit region by a formula, the pattern of the light reflection structure is formed according to the pattern interval (d _n ) and the correction pattern interval (f _n ). It provides a light guide plate characterized in that.

Therefore, the present invention establishes the theory of design technology to find the optimal conditions for realizing the best performance while minimizing the development period of the light guide plate pattern, and has the effect of manufacturing a light guide plate of a new model based on the result.

Description

Light Guide Plates {THE LIGHT GUIDE PLATE FOR THE BACK LIGHT}

The present invention relates to an optimal light guide plate having shortened development time while obtaining uniform luminance characteristics by forming a light reflection structure on the light guide plate using a formalized formula.

In general, display devices are one of the key electronic products 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 to totally reflect the light generated from the light source so that the entire light guide plate is evenly illuminated. For example, it is in charge of the midwifery who is replacing the display device represented by cathode ray tube (CRT) with liquid crystal display (LCD).

It is the light guide plate that the backlight performance is different among manufacturers and products, and the design of the light guide plate is the most important task in the development of the backlight.

Despite the fact that the backlight is an important component to be an essential part of the LCD device, the development of new technology, which is a qualitative level, is not making much progress because of the quantitative development.

The core of the technology related to the backlight is the light guide plate design technology. 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 has a problem that it is difficult to realize a competitive product development because the ability to respond to the new product is released a lot.

In addition, there is a problem such as developing a pattern based on experience without a formula for formulating a pattern design for a light reflection structure formed on the light guide plate.

The present invention has been devised to solve these problems, and the present invention provides an optimal light guide plate having shortened development time while obtaining uniform luminance characteristics by forming a light reflection structure on the light guide plate using a formula. There is this.

Another object of the present invention is to provide a light guide plate that can obtain uniform characteristics by using a standardized correction formula when a light reflection structure is formed on a light guide plate by using the light reflection formula.

It is still another object of the present invention to provide a light guide plate having shorter development time while obtaining uniform luminance characteristics by forming light reflection structures having different depths for each unit region.

1 is a flow chart showing an embodiment of a light guide plate pattern design method according to the present invention,

FIG. 2 is a diagram illustrating surface luminance values in a light guide plate having V grooves formed at equal intervals.

3 is a graph comparing the measured value and the calculated value when the formula of the present invention is applied,

Figure 4 is a graph showing the luminance characteristic curve for the light guide plate of 15 inches size manufactured by applying the present invention,

5 is a flowchart illustrating another embodiment of a light guide plate pattern design method according to the present invention.

In order to achieve the above object, in one embodiment of the present invention, a light reflecting structure is formed at equal intervals, and the light reflectance (R) by the light reflecting structure and the reflectance of the nth unit region divided by the light reflecting structure ( R _n ) and the pattern interval (d _n ) of the n-th unit region and the correction pattern interval (f _n ) for the luminance non-uniform unit region is determined by the formula to provide a light guide plate, characterized in that to form a pattern of the light reflection structure do.

In addition, the present invention, when the light reflecting structure is formed in the same pattern, the light reflectance (R)

I _n = I _o (1-R) ^n-1 R, I _o : Total incident light

The problem mentioned above is solved as a light guide plate characterized by the above-mentioned.

In addition, in the present invention, when the number of unit regions is N and the amount of light emitted from each unit region is uniform, the reflectance R _n of the nth unit region is set to R _n = 1 / {N- (n-1) } The problem mentioned above is solved as a light guide plate characterized by the above-mentioned.

In addition, according to the present invention, the pattern interval d _n of the nth unit region is determined.

d _n = R / R _n ㆍ L / N, L: length of light guide plate

The problem mentioned above is solved as a light guide plate characterized by the above-mentioned.

In addition, according to the present invention, the correction pattern interval f _n of the nth unit area is determined.

f _n = R / [2R _n -{(1 / N) + (ΔI _n / I _o )}] L / N,

ΔI _n = increased amount of light in the nth unit area

The problem mentioned above is solved as a light guide plate characterized by the above-mentioned.

In addition, the present invention, the light reflecting structure is a light guide plate, characterized in that formed on the back of the light guide plate using one of light scattering printing method, V groove method, U groove method, orthogonal time signal method, amorphous time signal method, OPI method. The above problem is solved.

In addition, the present invention solves the above-described problems as a light guide plate, characterized in that the light guide plate is produced using one of a mold manufacturing method, a printing method, a V cutting method, a U cutting method.

In order to achieve the above object, in another embodiment of the present invention, light reflecting structures having different depths are formed at equal intervals to measure light reflectance (R) by the light reflecting structures, and the reflectance (R _n ) of the unit region is measured. After determining the pattern depth (h _n ) of the n-th unit region corresponding to the reflectance (R _n ) and the correction pattern depth (j _n ) for the luminance nonuniformity unit region from the light reflectance (R) to determine the light The light guide plate which provided the pattern of a reflective structure is provided.

In addition, in the present invention, when the number of unit regions is N and the amount of light emitted from each unit region is uniform, the reflectance R _n of the n-th unit region is changed to R _n = 1 / {N- (n-1 The above-mentioned subject is solved as a light guide plate characterized by the above-mentioned.

The present invention also provides a light reflectance (R _s ) for the luminance nonuniformity unit region.

I _n = I _o (1-R _s ) ^n-1 R _s , I _n : light quantity in nth unit area, I _o : total incident light quantity

After determining by using the light guide plate, characterized in that the correction pattern depth j _n corresponding to the difference between the light reflectance (R _n ) and the light reflectance (R _s ) was determined from the light reflectance (R). Solve.

In addition, the present invention solves the above-described problems as the light guide plate, characterized in that the light reflection structure is formed on the rear surface of the light guide plate using the V groove method or the U groove method.

In addition, the present invention solves the above-described problems as a light guide plate, characterized in that the light guide plate is produced using one of a mold manufacturing method, a printing method, a V cutting method, a U cutting method.

The objects, features and advantages of the present invention will be more readily understood by reference to the accompanying drawings and the following detailed description.

The present invention proposes a light guide plate that is optimally realized by shortening the development time while obtaining uniform luminance characteristics by forming a light reflection structure on the light guide plate using a formulated formula.

A process for quickly obtaining a light guide plate pattern having uniform luminance characteristics will be described with reference to FIGS. 1 to 5.

1 is a flow chart showing an embodiment of a light guide plate pattern design method according to the present invention.

First, the standard of the light guide plate to be manufactured is selected. The design of the light guide plate pattern using the present invention can be applied without limitation to the size of the light guide plate, that is, the size of the width or length.

When the size of the light guide plate is selected, the position where the light source is to be installed is selected from four corners of the light guide plate. The light incident from the selected light source is totally reflected into the light guide plate and is reflected by the light reflection structure on the rear surface of the light guide plate to have a function as a light guide plate for a backlight.

Next, the light reflection structure is formed on the light guide plate at equal intervals (S100). In this case, an area in which one light reflection structure exists is defined as a unit area, and the light reflection structure is preferably the same pattern for each unit area. The width of each unit region is made constant in the direction of light travel, and the width of the unit region is preferably a value capable of forming at least one light reflecting structure having a minimum reflectance.

The light reflection structure is formed on the rear surface of the light guide plate using one of light scattering printing method, V groove method, U groove method, orthopedic signal method, amorphous time signal method, and OPI method.

The light scattering printing method is to form a material having high light reflection efficiency on the light guide plate by printing method, and the groove method is to engrave V, U, square or circular grooves directly on the light guide plate or to form the mold.

Therefore, in the light scattering printing method, the printing material having the same area is formed, and the V groove method, the U groove method, the standard time signal method, the amorphous time signal method, and the OPI method are formed with the same depth.

When there are N + 1 light reflecting structures formed on the light guide plate, N unit regions are uniformly formed from one end face to which the light source is incident to the other end face of the light guide plate.

After the light reflection structure is formed in step S100, the light reflection structure is assembled in a backlight state to measure the light amount I _n of the n-th unit region (S110). And determines the optical reflectivity (R) and n-reflectivity (R _n) of the first unit area of the light reflecting structure (S120).

When the amount of light I _n measured at step S110 is applied to Equation 1 to solve the system of simultaneous equations, the light reflectance R due to the light reflection structure may be determined.

,

I _o : Total incident light

For example, when the light reflecting structure using the light scattering printing method is formed on the light guide plate, Equation 1 may determine the reflectance according to the size of the printed light reflector area.

In addition, when the V groove or another type of light reflector is processed and formed directly on the light guide plate, or the light reflector is engraved on the mold to be formed on the light guide plate, the light reflectance according to the processing degree of the light reflector can be determined.

If the measured value of the total incident light is accurate, the light reflectance R by the light reflection structure may be determined by applying the light amount I _n measured in step S110 to Equation 1.

Table 1 shows the light quantity measured values and calculated values of a 15-inch light guide plate having equally spaced V grooves.

Unit area (N) Measured value (unit: cd / m ² ) Calculated value (unit: cd / m ² ) Measuring conditions 10 681 828 Light guide plate thickness 4.5mm Applied voltage 9.1V Tube current 244mm Measuring distance 70cm 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

In Table 1, the R value of the 15-inch light guide plate is 1.097%, and FIG. 2 shows a photometric graph of the 15-inch light guide plate, and FIG. 3 shows a graph comparing the measured value (dotted line) and the calculated value (solid line). Is shown. Since the amount of light derived from each unit region is the amount of light derived per unit area, this may be referred to as luminance at the light guide plate surface. Thus, the measured value represents a luminance value, and the unit is used for cd / m ^2.

Comparing Table 1 with FIG. 2, the amount of light for each unit region is high at the incidence end of the light guide plate, and the light quantity decreases as the light is moved away from the incidence end of the light guide plate. This is because the light reflection structures formed in each unit region are all the same structure, and the light reflectance R due to the light reflection structure is constant.

Since the LGP is divided into N unit areas, the amount of light emitted from each unit area must be uniform to obtain uniform optical characteristics on the surface of the LGP. When the amount of light emitted from each unit region is uniform, the reflectance R _n of the nth unit region is determined by Equation 2 below.

When the amount of light emitted from each unit region satisfies I _o / N, a light guide plate having an ideal shape can be manufactured.

When the light reflection structure of the light guide plate is a light scattering printing method, the printing area is determined as much as the reflectance R _n in each unit region. In this case, the printed pattern may be a printed pattern having a smaller area than the end portion of the light guide plate through which the printing area of the light incident side is directed.

When the light reflection structure of the light guide plate is a V groove having a constant depth, the reflectance R _n of each unit region is determined differently by adjusting the interval of the V groove.

For example, when the light reflectance R of the V groove having a constant groove depth is 0.01, the reflectance R ₁ of the first unit region should have a reflectance smaller than R in order to obtain a uniform amount of light. If R ₁ is 0.001, since 1/10 of R, 1/10 V grooves may be formed in the first unit region.

However, such a thing is practically impossible, and if one V groove is formed in an area 10 times the length of the unit area, the same effect can be obtained.

The pattern interval d _n of the n-th unit region is determined using the light reflectance R and the reflectance R _n determined in step S120 (S130). When the length of the light guide plate is L, the pattern interval d _n of the n-th unit region is determined by Equation 3 below.

The light guide plate prototype is manufactured by forming a light reflection structure on the light guide plate according to the pattern interval d _n determined in step S130 (S135). At this time, the light guide plate prototype is manufactured using one of a mold manufacturing method, a printing method, a V cutting method, and a U cutting method.

Table 2 and FIG. 4 show examples of measuring the amount of light on a surface after processing a pattern on a light guide plate using the pattern interval determined for each unit region as described above.

Unit area (N) Measured value (unit: cd / m ² ) Unit area (N) Measured value (unit: cd / m ² ) 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

Referring to Table 2 and Figure 4, it can be seen that the uniformity is 97.5% and the pattern processing results agree well with the theoretical design.

However, when the measured value of the light guide plate prototype is examined in detail, it can be seen that there are relatively errors at the inlet and the end of the light guide plate. This causes the error by assuming that light is only a one-dimensional vector incident perpendicularly to the incident surface.

Incident light has a spectral distribution characteristic close to an elliptic state. Therefore, the incident light proceeds radially, and in particular, it is radiated within the total reflection angle at the incidence portion and is not totally reflected inside the light guide plate, but is directly directed to the light guide plate surface. The emitted light is observed high in the left part of the graph.

In the end portion of the light guide plate, since the light propagated into the light guide plate is reflected at the end of the light guide plate, the light proceeds back to the inside of the light guide plate.

The light is reflected back at the end of the light guide plate because light is reflected due to a difference in refractive index when light travels from the dense medium to the medium.

In order to correct the portion where the luminance increases at both ends, the present invention measures the amount of light ΔI _n increased in the nth unit region (S140), and determines the correction pattern interval f _n for the luminance nonuniformity unit region. (S145).

The correction pattern interval f _n of the n-th unit region is determined by Equation 4.

,

The light guide plate is manufactured using the pattern interval d _n determined in step S130 and the correction pattern interval f _n determined using Equation 4 (S150).

In this case, as in step S135, a light guide plate is manufactured using one of a mold manufacturing method, a printing method, a V cutting method, and a U cutting method.

Although it is possible to obtain the reflectance using the light guide plate pattern design formula provided by the present invention, it is possible to obtain it simply by hand, but another object of the present invention is to use a minimum time for pattern design. Therefore, it is preferable to implement and use the above-described design formula as a light guide plate pattern design program for calculating the reflectance for each unit region.

5 is a flowchart illustrating another embodiment of a light guide plate pattern design method according to the present invention. In the embodiment of FIG. 5, light reflecting structures are formed on the light guide plate at equal intervals, and their depths are different for each unit region.

First, as described above, the position of the light source is selected from the standard of the light guide plate to be manufactured and the four corners of the light guide plate.

Then, light reflecting structures having different depths are formed on the light guide plate at the same interval (S200). At this time, the light reflection structure is formed on the rear surface of the light guide plate by using the V groove method or the U groove method, and preferably have the same pattern.

The width of each unit region is made constant in the direction of light travel, and the width of the unit region is preferably a value capable of forming at least one light reflecting structure having a minimum reflectance.

When there are N + 1 light reflecting structures formed on the light guide plate, N unit regions are uniformly formed from one end face to which the light source is incident to the other end face of the light guide plate.

Next, the light reflectance R according to the depth of the light reflection structure is measured (S210), and the reflectance R _n of the nth unit region divided by the light reflection structure is determined (SS220).

When the number of unit regions is N and the amount of light emitted from each unit region is uniform, the reflectance R _n of the n-th unit region is determined by Equation 2 below.

Next, the pattern depth h _n of the nth unit region corresponding to the reflectance R _n is determined from the light reflectance R measured in step S210 (S230), and the pattern depth h _n is applied to the light guide plate according to the pattern depth h _n . The light reflection structure is formed (S235) to manufacture a light guide plate prototype.

At this time, the light guide plate prototype is manufactured using one of a mold manufacturing method, a printing method, a V cutting method, and a U cutting method.

Since the brightness increases as described above at the inlet and end of the light guide plate prototype, this part should be corrected.

To this end, the light amount I _n of the n th unit region is measured (S240), and the light reflectance R _s of the luminance nonuniformity unit region of the light guide plate is determined using Equation 5 (S245). Solving Equation 5 by the simultaneous equation, it is possible to determine the light reflectance (R _s ) for the luminance nonuniformity unit region.

,

I _o : Total incident light

When the light reflectance (R _s ) is determined in step S245, a difference from the light reflectance (R _n ) determined in step S220 may be obtained.

Therefore, the correction pattern depth j _n corresponding to the difference between the light reflectance R _n and the light reflectance R _s is determined from the light reflectance R (S250), and the pattern depth h _n and the correction pattern depth are determined. A light guide plate is manufactured by (j _n ) (S260).

In this case, as in step S235, a light guide plate is manufactured using one of a mold manufacturing method, a printing method, a V cutting method, and a U cutting method.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention defined in the appended claims.

As described above, the present invention has an effect of efficiently, precisely, and quickly designing a light guide plate that greatly influences the performance of a backlight without using experience, and using a formula.

In the case of the 15-inch light guide plate designed using the formula of the present invention, it was possible to manufacture a backlight having a characteristic of 97.5% of luminance uniformity, which was typically only 80 to 90%.

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

Claims (12)

The light reflection structure is formed at equal intervals, and the light reflectance (R) by the light reflection structure and the reflectance (R _n ) of the nth unit region divided by the light reflection structure and the pattern interval (d) of the nth unit region _n ) and a correction pattern interval f _n for the luminance nonuniformity unit region are determined by a formula to form a pattern of the light reflection structure. The method of claim 1, wherein the light reflectance (R) is When the light reflection structure is formed in the same pattern, I _n = I _o (1-R) ^n-1 R I _o : Total incident light Light guide plate, characterized in that determined using. The method of claim 2, wherein when the number of unit regions is N and the amount of light emitted from each unit region is uniform, the reflectance (R _n ) of the n-th unit region is R _n = 1 / {N- (n-1)} The light guide plate characterized by the above-mentioned. The pattern interval d _n of the n-th unit area is d _n = R / R _n L / N, L: length of light guide plate The light guide plate characterized by the above-mentioned. The method of claim 4, wherein the correction pattern interval f _n of the n-th unit area is f _n = R / [2R _n -{(1 / N) + (ΔI _n / I _o )}] L / N, ΔI _n = increased amount of light in the nth unit area The light guide plate characterized by the above-mentioned. The light reflecting structure of any one of claims 1 to 5, wherein A light guide plate, characterized in that formed on the back of the light guide plate using one of light scattering printing method, V groove method, U groove method, orthogonal time signal method, amorphous time signal method, OPI method. The light guide plate according to any one of claims 1 to 5, wherein the light guide plate Light guide plate, characterized in that produced using one of the mold manufacturing method, printing method, V cutting method, U cutting method. Light reflectance structures having different depths are formed at equal intervals to measure light reflectance (R) by the light reflecting structure, determine the reflectance (R _n ) of the unit region, and then _n corresponding to the reflectance (R _n ). And a pattern depth of the light reflection structure is formed by determining the pattern depth (h _n ) of the second unit region and the correction pattern depth (j _n ) of the luminance nonuniformity unit region from the light reflectivity (R). The method according to claim 8, wherein when the number of unit regions is N and the amount of light emitted from each unit region is uniform, the reflectance R _n of the n th unit region is R _n = 1 / {N- (n-1)} The light guide plate characterized by the above-mentioned. 10. The method of claim 9, wherein the light reflectance (R _s ) for the luminance nonuniformity unit area I _n = I _o (1-R _s ) ^n-1 R _s , I _n : light quantity in n-th unit area, I _o : total incident light quantity The light guide plate, characterized in that the correction pattern depth j _n corresponding to the difference between the light reflectance (R _n ) and the light reflectance (R _s ) is determined from the light reflectivity (R). The light reflecting structure of any one of claims 8 to 10, wherein A light guide plate, characterized in that formed on the back of the light guide plate using a V groove method or a U groove method. The light guide plate according to any one of claims 8 to 10, wherein the light guide plate is Light guide plate, characterized in that produced using one of the mold manufacturing method, printing method, V cutting method, U cutting method.