KR20120043221A - Method for forming pattern of a light guided plate using a laser processing apparatus - Google Patents

Abstract

PURPOSE: A method for forming pattern of a light guide plate is provided to improve brightness and regularity of the light guide plate. CONSTITUTION: The density distribution of the light guide plate dot pattern is adjusted and is designed. The designed data is transformed into image data by being gray scaled in a predetermined step. A controller assigns the power of laser in order to correspond to the gray scaling step, reads out the gray scaled image data, and irradiates laser to the light guide plate.

Description

Method for forming pattern of a light guided plate using a laser processing apparatus}

The present invention relates to a method of forming a pattern on a light guide plate by using a laser processing machine. More particularly, in order to improve the brightness and uniformity of the light guide plate, the gray distribution of the density distribution of the light guide plate dot pattern and the power of the laser are increased. The present invention relates to a method of forming a light guide plate pattern by dividing and allocating to correspond to a gray scaling step and scanning the allocated laser beam on the light guide plate.

Recently, with the rapid development of semiconductor and information technology, a liquid crystal display (LCD) device having light weight, high resolution, low power, and environmentally friendly advantages has been widely used. Liquid crystal displays have a wide range of applications, from small display devices such as mobile communication terminals, navigation, handheld game machines or laptops to large display devices such as desktop computers and televisions.

Since LCD is a passive device that does not emit light, it needs a backlight unit in the form of a surface light source that makes the entire screen uniform. Among the components constituting the backlight unit, the light guide plate functions to guide light emitted from the light source to the liquid crystal panel with uniform brightness, and a reflective dot pattern causing diffuse reflection to emit light incident inside the light guide plate to the outside of the light guide plate. Is formed.

As a method of processing a dot pattern on a light guide plate, there are a printing method, a mechanical method using cutting and injection processing, and a laser processing method using a laser beam.

The printing method prints the polymer ink on the original plate by using a method such as screen printing to form a pattern. Such a printing method requires an additional facility such as an oven, which requires a large area of equipment and has a high defect rate in a large light guide plate. In addition, the mechanical method using cutting and injection processing has a problem that the processing time is long, the production efficiency is low, and it is difficult to freely adjust the pattern.

A light guide plate processing method using a laser beam is a method of generating a pattern consisting of a plurality of dots having a certain rule on the surface of the light guide plate by irradiating a laser beam directly on the surface of the light guide plate while moving the laser head. It is suitable for processing light guide plates used in 3D TVs and the like of areas.

As a conventional laser processing method, a galvano scanning method is disclosed in Korean Patent Laid-Open No. 2001-0099123. In the galvano scanning method, an f-theta lens is used to form the same focal point in the entire processing area where the laser beam is scanned. When the f-theta lens is used, the f-theta lens is larger than 10 inches (240 mm). f-θ) There is a problem that the light guide plate of a large area cannot be processed due to distortion caused by the size of the lens and lens aberration.

On the other hand, as a laser processing method that does not use a galvano scanner, the registered utility model No. 324786 discloses a method in which the laser head is reciprocally driven by a belt. Acceleration and deceleration are inevitable, and the average processing speed has been slow, which has limited productivity. Recently, the high speed linear motor (LM) is used instead of the rotating motor to increase the processing speed of 4m / sec or more. However, it takes 3-4 minutes to produce the 46-inch light guide plate because the deceleration section occurs because of the reciprocating drive method. There is a limit to productivity improvement.

Recently, a light guide plate processing apparatus for controlling focus and beam size using a compensation control method without using an f-theta (f-θ) lens has been developed (Patent Application No. 10-2010-0069676), and conventional galvano scanning A large area light guide plate of 40 inches to 70 inches, which was not feasible with the method, can be processed in a short time, thereby greatly improving productivity.

In the conventional method for processing a dot pattern using a laser processing machine, an intermittent linear dot pattern is formed as shown in FIG. 1 by scanning a laser beam while reciprocating a laser head. In the conventional method, the brightness and uniformity of the light guide plate are adjusted by adjusting the size of the dot, the distance between the dots in the horizontal direction (X pitch), and the distance between the dots in the vertical direction (Y pitch) to adjust the design data having the coordinate and length information of the dots. Converted to DXF format.

However, the developed compensation control type long focus laser processing machine has a problem in that it is difficult to apply data having existing length information because it is a pulse emission method rather than a conventional continuous emission method.

In the pattern forming method using the laser processing machine according to the present invention for solving the above problems, the gray scale of the density distribution of the light guide plate dot pattern and gray power of the laser to improve the brightness and uniformity of the light guide plate. The present invention provides a method of forming a light guide plate pattern by dividing and allocating the corresponding laser beams and scanning the allocated laser beams.

In order to achieve the above object, the light guide plate pattern forming method using the laser processing machine according to the present invention comprises the steps of: designing by adjusting the density distribution of the light guide plate dot pattern in order to improve the brightness and uniformity of the light guide plate in the pattern generating unit; Converting to grayscale image data by a predetermined step; dividing and allocating the power of a laser to correspond to the grayscale step in the controller; and reading the grayscaled image data in the controller and reading the image data into the image data. Outputting the allocated laser power and scanning the light guide plate.

The density distribution of the light guide plate dot pattern may be adjusted by using a Gaussian distribution function.

In addition, gray scaling is characterized in that 2 ⁿ (n is an integer of 1 to 10) step.

In addition, the image data is a non-vector image having an image on a pixel in any one of graphic formats of BMP, TIFF, JPEG, GIF, PNG, and PCX.

In addition, the width and length of the light guide plate are divided at predetermined intervals (X pitch, Y pitch) to form a cell of lattice, and the dot pattern is arranged or unarranged in each cell so that the pattern arrangement becomes a diamond shape. It is done.

In addition, in order to adjust the density distribution of the dot pattern, it is characterized by varying the X pitch and the Y pitch.

In addition, in order to vary the arrangement of the dot pattern, an offset value is added to the X-axis to arrange odd lines and even lines alternately.

Further, in order to improve the brightness and uniformity, the dot pattern is made circular and the dot size (diameter) is changed.

In addition, the depth of the dot pattern is characterized in order to improve the brightness and uniformity.

The pattern forming method using the laser processing machine according to the present invention for solving the above problems is to grayscale the density distribution of the light guide plate dot pattern and to divide and assign the power of the laser to correspond to the grayscaling step. By scanning the laser power on the light guide plate, the brightness and uniformity of the light guide plate can be improved.

In addition, it is possible to produce a light guide plate of high brightness even in the working area of more than 300mm, and even a large light guide plate of 40 to 70 inches can be processed at high speed to mass-produce high quality light guide plate with high productivity.

1 is a view showing a dot pattern of a conventional pattern forming apparatus
2 is an overall configuration diagram of a laser processing machine according to an embodiment of the present invention
3 is a flowchart of steps according to an embodiment of the present invention.
4 illustrates a dot pattern formed according to an embodiment of the present invention.
5 is a cross-sectional view of a light guide plate of a dot pattern formed according to an exemplary embodiment of the present invention.
FIG. 6 is a view illustrating a dot pattern with uniform pitches of cells of the X-axis and the Y-axis formed according to an embodiment of the present invention. FIG.
FIG. 7 is a diagram in which a pattern of dots formed according to an embodiment of the present invention is shifted between odd lines and even lines; FIG.
8 is a view illustrating a dot pattern in which pitches of cells of the X-axis and the Y-axis formed in accordance with an embodiment of the present invention are uneven;
FIG. 9 is a diagram illustrating a dot pattern in which a pitch of a cell of an X-axis formed according to an embodiment of the present invention is widened. FIG.

Hereinafter, an embodiment of a light guide plate pattern forming method using a laser processing machine according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings of the present invention, the size or dimensions of the structures are shown to be enlarged or reduced than the actual to clarify the present invention is not limited to the drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used to refer to the same components as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

2, the compensation control method long focus laser processing machine used in the present invention includes a pattern generator 101 for generating a pattern of a light guide plate by a large program, a laser oscillator 105 for oscillating a laser beam, and a focal point ( A long focal length correcting device 107 for forming and correcting a silk, a digital mirror 112 for scanning a laser beam vertically and horizontally, the laser oscillating part 105, a long focal length correcting device 107, and a digital And a control unit 103 for controlling the mirror unit 112.

The pattern generator 101 is a computer equipped with a pattern design program designed to adjust the density distribution of the light guide plate dot pattern to improve the brightness and uniformity of the light guide plate 115. The pattern generation program includes a size, a light source and a pattern of the light guide plate. Consider the shape and density of the simulation and generate the pattern. At this time, the image data formed by the denseness of the dot pattern (the low density of the dot pattern is brightened and the high density is darkened, or vice versa) can be grayscaled in a predetermined step to generate image data. have.

The laser oscillator 105 generates a laser beam by controlling the continuous load ratio of the laser according to the pattern data by controlling the laser according to the pattern data read from the pattern generator 101. The laser's output is sensitive to the surrounding environment, especially temperature, so temperature control is essential. Therefore, in order to monitor and control the output of the laser beam, a beam splitter should be installed on the exit side of the laser oscillator 105 to divide and measure a part of the output to maintain the stability of the laser by feedback control. The output ratio of the laser oscillation section 105 to be divided here is suitable for 0.5% to 2%.

Lasers include pulsed or continuous wave gas lasers and solid state lasers, including infrared (IR) and ultraviolet (UV) lasers. Examples of gas lasers include carbon dioxide (CO ₂ ) lasers, excimer lasers, argon (Ar) lasers, krypton (Kr) lasers, and the like. Examples of solid state lasers are yttrium-aluminum garnet (YAG) lasers, YVO4 lasers, and YLF lasers. , YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: sapphire laser, Y2O3 laser and the like. Here, the solid state laser may use crystals of YAG, YVO 4, YLF, YAlO ₃ , and the like doped with Cr, Nd, Er, Ho, Ce, Co, Ti, Yb, or Tm. Lasers for light guide plate processing are preferably lasers having a wavelength range of 10 μm, and pulse oscillation type CO ₂ lasers are preferable.

The controller 103 controls the laser oscillator 105, the long focus correcting device 107, and the digital mirror 112 according to the pattern data generated by the pattern generator 101 to the light guide plate 115 to be processed. The pattern is generated with a predetermined depth and size, and the coordinates (x, y) for the area to be longitudinally and horizontally processed, and the rotation angles of the corresponding digital mirrors 109 and 111 are calculated. In addition, the output of the laser oscillator is controlled by comparing the actual output with the target output. At this time, in order to maintain the stability of the laser output, a beam splitter is installed on the output side of the laser oscillator 105 to measure a part of the output by dividing. In addition, since the controller 103 can control the power of the laser oscillated by the laser oscillator 105 to control the light guide plate 115 by outputting the laser power corresponding to the image data generated by the pattern generator 101. Control to scan).

The digital mirror unit 112 uses a dynamic long focal length corrector 107 instead of using an f-theta lens to process a large light guide plate to form a longer focal length deviation. At the same time, the lens is variable to focus, and the digital mirror 112 is driven in conjunction with the long focus compensator 107 so that all patterns in the processing area are in-focus. The digital mirror unit 112 includes a first digital mirror 111 rotating along the x axis and a second digital mirror 109 rotating along the y axis, and the first and second digital mirrors 111 and 109 are mirrors. First and second rotary motors 201 and 211 to drive the. The first and second digital mirrors 111 and 109 and the first and second rotary motors 201 and 211 further include first, second, third and fourth cooling means 203, 205, 207 and 209. The means can be water-cooled or electronic cooling means.

The long focus correcting apparatus 107 is positioned between the laser oscillator 105 and the digital mirror 112, and reduces the deviation of the focal point according to the rotation angle of the digital mirror 112 and at the same time the light guide plate 115 of the light guide plate 115. It is a long focal length correction device which forms a focal point in all the processing areas of a light guide plate by changing a lens in order to correct | deviate the focus which moved away according to the coordinate position. In order to prevent the laser beam from being diffused due to the long focal point to change the size of the focal beam and the laser power density, a beam size adjusting device using a variable lens is disposed between the laser oscillator 105 and the long focal compensator 107. Position it. The long focus compensator 107 has a fixed first block lens and a variable agent which is paired with the first block lens and diffuses the laser beam generated by the laser oscillator 105 to project the first block lens. And a first lens driving means for driving the first concave lens to form a long focal point while keeping the first concave lens under optical control with the first concave lens under the control of the first concave lens. The lens driving means is at least one of a linear motor, a voice coil motor or a piston type driving means. In addition, the preferred focal length of the long focus correcting apparatus 107 is 1 to 3 m.

The beam size adjusting device is positioned between the laser oscillator 105 and the long focus correcting apparatus 107, and diffuses the second block lens and the laser beam generated by the laser oscillator 105 to diffuse the second beam lens. The second concave lens projecting onto the block lens and the second block lens are optically aligned with the second lens, and the second concave lens is varied while being interlocked with the long focus compensator 107 to scan the light guide plate 115. And second lens driving means for adjusting the beam size.

As shown in FIG. 3, the light guide plate pattern forming method using the compensation control method long focus laser processing machine according to the present invention,

1. Designing by adjusting the density distribution of the light guide plate dot pattern to improve the brightness and uniformity of the light guide plate in the pattern generator

2. Converting the designed data into image data by gray scaling in a predetermined step

3. The control unit divides and allocates the power of the laser to correspond to the gray scaling step.

4. The control unit reads the gray scaled image data, outputs the laser power allocated to the image data, and scans the light guide plate.

Each of the above steps will be described in order as follows.

1. Designing by adjusting the density distribution of the light guide plate dot pattern in order to improve the brightness and uniformity of the light guide plate in the pattern generator (S1)

The pattern generating unit 101 is a computer on which a pattern design program is mounted, and input parameters such as the arrangement of the light source of the light guide plate (BLU), the light guide plate size, the light guide plate thickness, the dot shape and the size of the light guide plate to meet the specification of the light guide characteristics of the light guide plate are provided. Used as The density distribution of the dot pattern is adjusted by changing the size of the dots and the intervals between the dots (X pitch, Y pitch) in order to satisfy luminance and uniformity, which are important specifications among the concentrate characteristics. The density distribution can be easily adjusted by using the Gaussian distribution function, which is a probability distribution function. 4 shows a general light guide plate pattern formed by using a compensation control type long focus laser processing machine.

2. converting the designed data into image data by gray scaling in a predetermined step (S2)

To meet the desired luminance and uniformity for a particular BLU, the density distribution of the dot pattern in the side near the light source and in the center far from the light source is formed differently.

In general, the designed data is converted into DXF format having coordinate information and length information, which is read by a controller to control laser emission. However, in the case of the existing DXF format, a large amount of information must be processed at a high speed, which makes it difficult to use the control system because it is complicated, expensive, and cannot have laser output information for each pattern.

In the present invention, gray scaling of an image formed by the denseness of the dot pattern (where the density of the dot pattern is low and the high point is dark, or vice versa) can be gray scaled in a predetermined step. The gray scaled image is converted into a non-vector image format having an image in each pixel such as BMP, TIFF, JPEG, GIF, PNG, and PCX, and transmitted to the controller 103. The gray scaling step is a binary number of 2 ⁿ (n is an integer of 1 to 10), and preferably 16 to 256 steps.

3. The control unit divides and allocates the power of the laser to correspond to the gray scaling step (S3).

The controller 103 is a controller for controlling the power level of the laser oscillated by the laser oscillator 105 and divides and assigns the power level through a process of calculating to correspond to the gray scaled step. Corresponding by dividing the power level of the laser into one-to-one, one-to-many or many-to-one by corresponding to gray scaled steps.

4. The control unit reads the gray scaled image data, outputs the laser power allocated to the image data, and scans the light guide plate (S4).

The control unit reads the gray scaled image data from the pattern generator 101, divides the laser power allocated to the gray scale step in step S3 to the laser oscillator 104, and outputs the laser power to the light guide plate 115. Injecting.

FIG. 5 illustrates a cross-sectional view of a dot pattern formed according to gray scaled image data according to a power level in size (diameter) and depth change. The laser power levels are in the order a <b <c.

The present invention is designed by adjusting the density distribution of the dot pattern 117 of the light guide plate 115 in order to improve the brightness and uniformity of the light guide plate 115 in the pattern generator 101. That is, according to the present invention, the horizontal and vertical portions of the light guide plate 115 are divided at predetermined intervals (X pitch and Y pitch) without having a large amount of information on the length of data, thereby forming a grid cell and drawing a dot pattern in each cell. By arranging or disposing as shown in FIG. 6, the pattern arrangement may be diamond-shaped, thereby increasing the pattern formation speed, and may be applied to a large light guide plate 115.

In addition, in FIG. 7, when the light guide pattern is divided into X pitches and Y pitches, and the dots are uniformly arranged in the cells of the lattice, the control unit 103 changes the offset value on the X axis to change the arrangement of the patterns. By adding, the odd lines and even lines can be displaced. That is, as shown in FIG. 7, an offset value is added to the dot in at least one of the odd lines or the even lines to shift the shift. At this time, the shift does not go out of the cell. For example, if the distance between the dots is 2 mm, the diamonds are shifted by 1 mm.

In addition, in order to adjust the density distribution of the dot pattern, as shown in FIGS. 8 and 9, the ratio of the X pitch and the Y pitch may be varied into cells equal or unequal with respect to the X axis and the Y axis. Even if the X and Y pitches are varied, the diamond shape is maintained. 6 and 7 are diagrams formed of cells uniformly according to an embodiment of the present invention, while FIG. 8 is an X pitch of a cell with respect to a pitch of an X axis and a Y axis formed according to an embodiment of the present invention. Fig. 9 shows the non-uniform dot pattern 117 lengthened, and Fig. 9 shows the non-uniform dot pattern 117 shorter than the X pitch of the cell. That is, even when the pattern arrangement having the diamond shape is corrected for at least one of the X pitch and the Y pitch (when the pitch of the pattern cell is corrected), as shown in FIGS. 8 and 9, the odd lines and the even lines are different. Since regular patterns can be maintained, there is an effect of providing high quality high luminance characteristics and improved uniformity.

In addition, even if the pitch of the X-axis and the Y-axis is adjusted to non-uniform cells, providing high quality bright luminance outputs laser power allocated to gray scaled image data as shown in FIG. The size (diameter) of can form a pattern differently.

L: laser beam 101: pattern generator
103 control unit 105 laser oscillation unit
107: long focus correction device 109: second digital mirror
111: first digital mirror 112: digital mirror unit
115: light guide plate 117: dot pattern
201: first rotating motor 203: third cooling means
205: first cooling means 207: second cooling means
209: fourth cooling means 211: second rotating motor

Claims (9)

In the light guide plate pattern formation method using a laser processing machine,
Adjusting the density distribution of the light guide plate dot pattern to improve brightness and uniformity of the light guide plate in the pattern generation unit;
Converting the designed data into image data by gray scaling the predetermined data;
Dividing and allocating power of a laser to correspond to the gray scaling step in a control unit;
And reading the gray scaled image data from the controller and outputting the laser power allocated to the image data to scan the light guide plate. The method of claim 1,
Light guide plate pattern formation method characterized in that the adjustment of the density distribution of the light guide plate dot pattern using a Gaussian distribution function The method of claim 1,
Light guide plate patterning method characterized in that the gray scaling is 2 ⁿ (n is an integer of 1 to 10) step The method of claim 1,
Image data is a light guide plate pattern forming method characterized in that the non-vector image having an image on the pixel in any one of the graphic formats of BMP, TIFF, JPEG, GIF, PNG, PCX The method of claim 1,
The horizontal and vertical portions of the light guide plate are divided at predetermined intervals (X pitch, Y pitch) to form cells of lattice, and the dot pattern is arranged or unplaced in each cell so that the pattern arrangement becomes a diamond shape. Light guide plate pattern formation method The method of claim 5,
A light guide plate pattern forming method characterized by varying the X pitch and the Y pitch in order to adjust the density distribution of the dot pattern. The method of claim 1,
A light guide plate pattern formation method comprising displacing odd lines and even lines by adding an offset value to the X axis in order to vary the arrangement of dot patterns. The method of claim 1,
Light guide plate pattern forming method characterized by changing the dot size (circle) and the dot pattern to improve the brightness and uniformity The method of claim 1,
The light guide plate pattern formation method characterized by changing the depth of a dot pattern in order to improve brightness and uniformity.

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