JP2022032301A - Display panel capable of exposing images different in incident direction of light and manufacturing method thereof - Google Patents

Abstract

To provide a display panel capable of displaying different display images with respect to the incident light different in the incident direction from the end face of a light guide plate in the display panel using the light guide plate, and to provide a method for inexpensively manufacturing the display panel.SOLUTION: Projectors 17,18 are arranged, which project the incident lights AL, BL directed to each of vertical and horizontal end faces of a display panel using a resin light guide plate 10 whose plane shape is rectangular. In a predetermined area on the rear surface of the light guide plate 10, a plurality of groups of two kinds of groove dot groups are formed by providing a plurality of rows of V-shaped cross section with a small length extending in the direction orthogonal to the incident direction at a small interval and parallel to each other. Two kinds of different display images are exposed on the surface of the display panel.SELECTED DRAWING: Figure 15

Description

The present invention relates to a panel in which the light guide plate itself can be used as a display panel and can display different display images depending on the incident direction of light from the end face of the light guide plate, and a method for creating a mold for forming the light guide plate. It relates to a method of forming a light guide plate using a mold.

The light guide plate is a plate-shaped member that diffuses light incident from an end surface and radiates light to the surface, and is mainly used as a backlight for a liquid crystal display or a backlight for a signboard that emits light. The light guide plate used for the backlight is designed so that the surface of the light guide plate emits light uniformly.

On the other hand, there is also a method of designing the surface of the light guide plate to emit light in a certain pattern such as characters, symbols, or logo marks, and using the light guide plate itself as a display panel. Furthermore, when the light guide plate itself is used as a display panel, the display content can be changed by switching the light guide plates to be turned on for a plurality of light guide plates having different light emission patterns, and the direction to be instructed can be changed as necessary. It is possible to create a turn signal board that can be changed and a display panel that informs the state of the object (on / off, open / closed, etc.).

In order to develop display panels using such light guide plates for various purposes, it is desired to develop a technology that can mass-produce display panels at low cost. In addition, switching of display contents is an important factor when developing for various purposes, but at present, the same number of light guide plates as the number of light emitting patterns is required, and the number of light guide plates can be reduced to save the number of light guide plates. Space reduction and further cost reduction are desired. For this purpose, it is necessary to give the light guide plate a function of switching the display contents.

One of the methods for manufacturing a light guide plate is a method of pouring a resin into a pattern-processed mold (see, for example, Patent Document 1), which is often used for manufacturing a light guide plate used for a backlight of a liquid crystal display. The mold used in this method generally has a pattern formed by precision machining, and the manufacturing cost of the mold is high. If a display board is created by this method, an expensive mold is required for each light emission pattern, which is not profitable.

As a method for manufacturing a light guide plate that does not use a mold, there is a method of directly forming a recess in a resin plate by laser processing (see, for example, Patent Document 2). If a laser scanning optical system is used, recesses can be formed so as to emit light in a constant pattern, so that it can also be used as a method for creating a display panel. However, in the processing by laser scanning, the more recesses formed to create a display plate having a complicated pattern, the longer the processing takes, and the mass productivity is inferior to that in the processing by a mold. Although Patent Document 2 discloses a method of forming an inverted mold by electroforming using a laser-processed resin plate as a prototype, the manufacturing cost of the mold by electroforming is also high. However, in terms of mass productivity, it is more advantageous to mold using a mold, so the problem is how to inexpensively produce a mold for a light guide plate used as a display plate.

Patent Document 3 discloses a method for inexpensively producing a mold for a light guide plate by laser processing. In this method, the shapes of various laser processing marks for diffusely reflecting light have been studied, and the shapes are faithfully inverted and transferred to the resin to create a light guide plate. The study of the shape is for increasing the light diffusion effect on the surface of the light guide plate to increase the brightness of the light guide plate, and is not for giving the light guide plate a function of switching the display content.

Japanese Unexamined Patent Publication No. 2000-347185 Japanese Unexamined Patent Publication No. 2000-066029 Japanese Unexamined Patent Publication No. 2006-168260

The problem to be solved by the present invention is to solve the above-mentioned conventional problems, to provide a display panel that can be manufactured at a low price by using the light guide plate itself as a display panel and having a function of switching the display content depending on the light incident direction. And to provide a method for mass-producing the display panel at low cost.

The configuration of the present invention that solves this problem is
1) A light guide plate is used as the panel plate of the display panel, and by injecting light 90 ° different in the incident direction from the end face of the light guide plate, a large number of light spots different in the incident direction of the light are incident on the surface of the light guide plate. It is a display panel that can display the expressed display image.
For each of the two incident lights AL and BL having different 90 ° incident directions from the end face of the light guide plate, V-shaped grooves having a minute length extending in a direction orthogonal to the incident direction are formed at minute intervals. In addition, a large number of two types of groove dot groups formed by providing a plurality of rows in parallel are provided in a predetermined region on the back surface of the light guide plate, and the position where the groove dot group is provided is represented by the incident light of the display image. The configuration is such that the group arrangement patterns MA and MB are arranged so that they are the positions of the light spots.
When the incident light AL and BL on the end surface of the light guide plate are incident on a predetermined region on the back surface of the light guide plate while being totally reflected between the front surface and the back surface of the light guide plate, the incident light AL is orthogonal to the incident direction. The groove dots extending in the direction of light are reflected and diffused on the groove surface of the V-shaped groove with a minute length, and radiated from the surface of the light guide plate to visualize the groove dots as light spots. A display image can be expressed as a collective image of light spots due to incident light, and a cross section V with a minute length of another groove dot group extending in a direction orthogonal to the incident light even for incident light BL different by 90 °. By reflecting on the groove surface of the character groove and visualizing the groove dot group as light spots, a display image with a different pattern is displayed as a collective image of light spots, and further, minute amounts on the side parallel to the incident light. A display panel 2 capable of displaying different display images depending on the incident direction of light, in which a group of groove dots having a length is not reflected and is not visible and becomes a dark point and does not affect the appearance of the different display images. ) In the same groove dot group, among a plurality of rows of V-shaped grooves having a minute length extending in a direction orthogonal to the incident direction, the groove ends of the V-shaped grooves in the front and back are connected by a V-shaped groove. The planar shape of the V-shaped groove is made to be an oval shape, and a plurality of rows of V-shaped cross-sectional V-shaped grooves having the planar shape of the oval shape are formed in the groove dot group in the incident direction. Display panel that can display different display images depending on the incident direction of the described light 3) Many on the back surface of the light guide plate of the display panel that can display different display images depending on the incident direction of the described light. A method for manufacturing a display panel that forms a V-shaped groove in a cross section in the group of individually arranged groove dots.
A mold is irradiated with laser light so as to form a V-shaped cross-section groove in the groove dot group on the surface of the substrate to be a mold, and a mold having a concave inside and a convex portion of a burr on the outer periphery is formed. Next, the created mold is pressed against the resin plate to be the light guide plate at room temperature or in a state where the resin plate is softened by heating to the extent that the resin plate does not have fluidity, and the cross section V is processed against the resin plate. A display panel manufacturing method in which a character-shaped groove is formed, and a V-shaped groove in a group of groove dots on the back surface of the light guide plate is formed into a display panel by using the above method. 4) Pressure is adjusted. The die is pressed against the resin plate to act on the convex portion of the mold while reducing the action of the concave portion, whereby dots formed of oval grooves are formed on the resin plate. 3) It is in the manufacturing method of the display panel described.

The main points of the present invention that have achieved such a problem are a process of irradiating a substrate surface with a laser beam to form a plurality of dot-shaped processing marks to form a mold as a method of producing a light guide plate of the present invention, and the metal. It includes a step of forming a light guide plate whose display contents are switched depending on the incident direction of light using a mold.

Further, the dot-shaped processing marks are irradiated multiple times while scanning the irradiation position of the laser beam in a straight line, or the outer peripheral portion is oval and the inside thereof is recessed. Depending on the laser irradiation conditions, the periphery of the irradiation site rises and remains as burrs, and convex portions due to burrs are formed in the oval portion which is the outer peripheral portion of the dots. A mold is created by adjusting the positions of the dot-shaped processing marks so as to have a desired pattern and forming a plurality of them on the surface of the substrate.

In the process of molding the light guide plate using the mold, if the method of pouring the resin into the mold is used, the dot-shaped processing marks are faithfully inverted and transferred, and the light guide plate to be molded is incident from any side surface. Since the light diffusing effect on the surface of the light guide plate is large even for the emitted light, it is not suitable for the purpose of switching the display contents. Therefore, in the present invention, the mold is pressed against the resin plate at room temperature or in a softened state by heating the resin plate to the extent that the resin plate does not have fluidity. At this time, by adjusting the pressurizing pressure, the action of the convex portion due to the burr is made to act, while the action of the concave portion is reduced. On the surface of the light guide plate formed in this way, dots formed of oval-shaped fine grooves are formed by the convex portions formed by the burrs of the mold. When the method of pouring the resin into the mold is used, fine scratches on the surface of the mold are also inverted and transferred, so that the surface of the mold needs to have a polished surface close to a mirror finish. Since the mold is adjusted and pressed against the resin plate, the effect of fine scratches is small, and a substrate with a rougher polished surface than mirror finish can be used as the mold material, which also leads to lower cost of mold making. ..

Guidance between a dot formed as described above and having a V-shaped groove having a thin oval cross section and irradiating light from a direction perpendicular to the long side and a dot irradiating light from a horizontal direction. Comparing the light diffusion effect on the surface of the light plate, the former is much larger. Therefore, the light guide plate in which the dots are arranged in the same direction so as to have a constant pattern becomes a light spot with high visibility of the pattern when the light is irradiated from the direction perpendicular to the long side of the dots, and the length of the dots is high. When the side is irradiated with light from a horizontal direction, the visibility of the pattern becomes a dark spot, and dots with different directions of 90 degrees are mixed, and two types of dots with different directions are used as a constant pattern. The light guide plate arranged so as to be capable of switching the display content (display image) by changing the direction in which the light is incident by 90 degrees.

On the back surface of the light guide plate, a group arrangement pattern MA and a groove of a group of dots of a group of V-shaped cross-sections having a small number of minute lengths that hit each of two incident lights AL and BL having different 90 ° directions at right angles. A large number of dots are arranged in a predetermined pattern with the group arrangement pattern MB of the dot group.

Therefore, when the incident light AL is incident, the groove surface of the V-shaped groove of the group arrangement pattern MA of the groove dot group orthogonal to the incident light AL reflects the light and emits the reflected light from the surface of the light guide plate. A light spot is visually recognized by the group arrangement pattern MA of the groove dot group, and a predetermined light display image is formed by the light spot of the pattern.

In this case, since the other groove dot group MB is incident parallel to the V-shaped groove in the cross section, it has no reflection, or even if it is weak, it becomes a dark point and a light display image is not formed, and the dark point is not formed. Hidden as.

Next, when the incident light BL whose incident direction differs from the incident light AL by 90 ° is incident, the groove surface of the V-shaped groove in the cross section of the group arrangement pattern MB of the groove dot group reflects this incident light. The reflected light is emitted from the surface of the light guide plate, and the group arrangement pattern MB of the groove dot group is visually recognized as a point of light. On the other hand, the group arrangement pattern MA of the groove dot group does not reflect the incident light BL, so that it becomes a dark point.
In this way, it is represented as a display image of light of another pattern as a set of light points of the group arrangement pattern MB of the groove dot group with respect to the incident light BL.

In this way, different light display images can be displayed on the surface of the light guide plate (display panel) by switching the incident light AL and BL.

By using the incident light AL and BL as lighting / blinking light or colored light, the image of the light display image can be greatly emphasized.

In the present invention, a substrate to be a mold is irradiated with a laser beam to create a processing mark (a linear minute line having a short planar shape or a group of groove dots in which a plurality of rows of elliptical ones are arranged).
By pressing the created mold while heating the resin serving as the light guide plate to a predetermined temperature, a light guide plate (display panel) in which a large number of groove dot groups are created in a predetermined pattern is created. This method does not pour the resin into the mold, and since the groove dot group can be created by irradiating the laser beam, it can be created in a short time and at low cost.

In this way, the light guide plate having the function of switching the display contents can be mass-produced in a short time by press molding using a mold. Further, the mold used for molding can be inexpensively produced because it is only necessary to irradiate the mold while scanning the laser beam to form dots having a predetermined shape at positions having a desired pattern.

FIG. 1 is an explanatory diagram showing a process of producing a mold of the present invention. FIG. 2 is an explanatory diagram showing a method of forming dots, which are processing marks formed by laser light irradiation on the substrate surface 2a, and a planar shape of the dots 8 which are processing marks. FIG. 3 is an enlarged cross-sectional view taken along the line AA of FIG. FIG. 4 is an enlarged cross-sectional view taken along the line BB of FIG. FIG. 5 is an enlarged cross-sectional view taken along the line CC of FIG. FIG. 6 is an explanatory diagram showing a process of forming a light guide plate using a substrate 2 on which dots 8 which are processing marks are formed as a mold. FIG. 7 is an enlarged plan view showing an elliptical cross-sectional V-shaped groove on the molded light guide plate. FIG. 8 is an enlarged sectional view taken along the line DD of FIG. FIG. 9 is an enlarged cross-sectional view taken along the line EE of FIG. FIG. 10 is an enlarged cross-sectional view taken along the line FF of FIG. FIG. 11 is an enlarged perspective view illustrating the light diffusion characteristics of the light guide plate having the V-shaped cross section formed. FIG. 12 is an explanatory diagram showing a state of reflection of incident light by a V-shaped groove in cross section of the light guide plate. FIG. 13 is an enlarged explanatory view showing a group of groove dots consisting of five rows of V-shaped grooves having a planar shape of an oval shape. FIG. 14 is an explanatory diagram showing an arrangement state of two types of groove dot group 14 and a groove dot group 14 having a V-shaped cross section for reflecting incident light having two 90 ° differences. FIG. 15 is an explanatory diagram showing the group arrangement patterns MA and MB of the groove dot group 14 and the display image of the light and dark display for the light having a difference of 90 ° from the incident light of the display panel. FIG. 16 is an explanatory diagram showing the formation of dots having a minute length on a mold for producing a light guide plate having improved visibility. FIG. 17 is an enlarged cross-sectional view taken along the line GG of FIG. FIG. 18 is an enlarged cross-sectional view taken along the line HH of FIG. FIG. 19 is an enlarged sectional view taken along the line I-I of FIG. FIG. 20 is an enlarged plan view showing the plan shape of the V-shaped cross section having improved visibility from the V-shaped cross section of the elliptical plan shape of FIG. 11. 21 is an enlarged cross-sectional view taken along the line JJ of FIG. 22 is an enlarged cross-sectional view taken along the line KK of FIG. FIG. 23 is an enlarged sectional view taken along the line LL of FIG. FIG. 24 is an explanatory diagram showing a display image of the display panel of the direction indicator plate with respect to the incident light in the left-right direction of the display panel used as the direction indicator plate of the embodiment. FIG. 25 is an explanatory diagram showing a display image of the display panel with respect to the incident light in the vertical direction of the display panel as the direction indicator of the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a process of producing a mold of the present invention. The laser oscillator 1 emits a pulsed laser beam 3 for processing the substrate 2. The laser beam 3 is reflected by an X-axis mirror 4 and a Y-axis mirror 5 attached to a galvano motor (not shown), and is focused and irradiated on the surface 2a of the substrate 2 by the fθ lens 6. In the light collecting spot 7, the vicinity of the surface of the substrate 2 is instantly melted, evaporated and scattered, and a processing mark having a hemispherical recess is formed.

The X-axis mirror 4 and the Y-axis mirror 5 can change the reflection angle with high accuracy by the galvano motor, and the condensing spot 7 can be moved to an arbitrary place on the substrate surface 2a by the combination of the reflection angles. The position, movement locus, and movement speed of the focusing spot 7 can be set by a computer (not shown). The computer can also set the power, pulse width, and pulse period of the laser beam 3.

2 to 5 are views showing a method of forming a dot 8 on the surface 2a of a substrate, which has an oval outer peripheral portion and a concave inside thereof, and has a convex portion 8a due to burrs on the outer peripheral portion. As shown in FIG. 2, when the condensing spots 7 are partially moved so as to overlap each other and irradiated with the laser beam 3, the outer peripheral portion of the processing mark becomes an oval shape. FIG. 3 is an enlarged cross-sectional view taken along the line AA of the dot 8 of FIG. FIG. 4 is an enlarged cross-sectional view taken along the line BB of the dot 8 of FIG. FIG. 5 is an enlarged cross-sectional view taken along the line CC of the dot 8 of FIG. By adjusting the power of the laser beam 3, the pulse width, the period of the pulse, and the moving speed of the focused spot 7 so that the thermal influence on the periphery of the focused spot 7 is likely to occur, the burr 8a becomes an oval shape of the dot 8. It is formed along the outer peripheral portion.

FIG. 6 is a schematic view showing a process of forming a light guide plate using the substrate 2 on which the dots 8 are formed as a mold. In FIG. 6, the substrate 2 is drawn in the same line cross-sectional view as in FIG. 3, and the stage 9, the resin plate 10 and the jig 11 are also drawn as a cross-sectional view of the same surface. The steps are performed in the order of FIG. 6 (a), FIG. 6 (b), and FIG. 6 (c). In the procedure of FIG. 6A, the stage 9 is installed on the resin plate 10 serving as the light guide plate. The stage 9 has a built-in heater, and heats the resin plate 10 as needed to soften the resin plate to the extent that it does not have fluidity. The substrate 2 which is a mold is attached to the jig 11. The stage 9 and the jig 11 are attached to a press machine (not shown).

In the procedure of FIG. 6B, the press machine is operated to press the substrate 2 against the resin plate 10. At this time, the pressing pressure is adjusted to allow the burr 8a to act while reducing the action of the recess 8b. In the procedure of FIG. 6C, the pressurization is stopped and the substrate 2 is separated. By this series of procedures, a narrow groove 10a is formed on the resin plate 10 by the action of the burr 8a.

FIG. 7 is an enlarged plan view showing an outline of the dot 12 composed of the groove 10a. As shown in FIG. 7, the planar shape of the groove 10a is an oval shape. FIG. 8 is an enlarged cross-sectional view taken along the line DD of the dot 12 of FIG. 7, and the groove 10a is formed by the burrs of the circular portion of the dot 8 of FIG. 9 is an enlarged cross-sectional view taken along the line EE of the dot 12 of FIG. 7, and the groove 10a is formed by the burrs 8a shown in FIG. FIG. 10 is an enlarged cross-sectional view taken along the line FF of the dot 12 of FIG. 7, and the groove 10a is formed by the burrs 8a on the long side portion of the dot 8 shown in FIG.

11 and 12 are diagrams illustrating the light diffusion characteristics of the dots 12. FIG. 11 is a perspective view in which an XYZ axis is attached to a resin plate 10 which is a light guide plate on which dots 12 are formed for the sake of explanation. The dots 12 are formed on the surface of the resin plate 10 which is a light guide plate on the + Z axis side, and its long side is parallel to the Y axis. FIG. 12 is an explanatory diagram showing diffusion characteristics when light is incident from the end surface 10b of the resin plate 10 which is a light guide plate. The light 13 incident from the end surface 10b at a certain spread angle in the + X-axis direction propagates while repeating total internal reflection on the front surface and the back surface of the resin plate 10 which is a light guide plate, and a part of the light is propagated by the groove 10a. -Diffused in the Z-axis direction (surface side).

Even when light is incident at a certain spread angle from the end face 10c toward the + Y-axis direction, a part of the similarly incident light is diffused in the -Z-axis direction (surface side) by the groove 10a, but the diffusion thereof. The degree of is very small as compared with the case where light is incident from the end face 10b in the + X axis direction. This is because, as shown in FIGS. 8 and 10, the areas of the grooves 10a that contribute to diffusion differ greatly in each direction.

From the above, when the resin plate 10 which is a light guide plate is viewed from the −Z axis direction (front surface side), strong diffused light is observed when light is incident from the end surface 10b toward the + X axis direction. On the other hand, when light is incident on the end face 10c in the + Y-axis direction, only diffused light, which is much weaker than the former, is observed. Further, the dots 12 formed on the surface of the resin plate 10 which is the light guide plate on the + Z axis side (back surface) strongly diffuse light in the −Z axis direction in the back surface direction, but on the + Z axis side in the front surface direction. Does not diffuse much light. Therefore, if the dots 12 are arranged so as to have different light emission patterns on both the + Z-axis side of the back surface of the resin plate 10 which is the light guide plate and the −Z axis side of the front surface, the light guide plates having different display contents on the front surface and the back surface can be obtained. It is also possible to create it.

The light emitting pattern of the light guide plate 10 is designed by arranging the dots 12 of the group arrangement patterns MA and MB of the groove dot group in the manner of pointillism. At this time, the larger the difference in the diffused light intensity depending on the incident direction of the light, the more clearly the display content of the light guide plate 10 can be switched. In order to increase the difference in diffused light intensity depending on the incident direction of light, as shown in FIG. 13, light is emitted with a groove dot group 14 in which a plurality of dots 12 are arranged so that their long sides are parallel to each other. It is good to design the pattern.

Since the groove dot group 14 draws a pattern in the manner of pointillism with it as one point, the length 14a from one end to the other of the group arrangement patterns MA and MB of the groove dot group and the length 14b of the long side of the dot 12 The same degree makes pattern design easier. Further, as the number of dots 12 constituting the groove dot group 14 increases, the difference in diffused light intensity increases, but the length 14a also becomes longer accordingly. Further, the longer the length 14b of the long side of the dot 12, the larger the difference in diffused light intensity.

On the other hand, since the light emitting pattern of the light guide plate is drawn with the groove dot group 14 as one point, the length 14a and the length 14b are limited by the size of the light emitting pattern to be drawn and its resolution.

14 and 15 are examples of pattern design of the light guide plate 10 whose display contents can be switched. FIG. 14 shows the correspondence between the light spots ◯ and dark spots ● in FIG. 15 and the groove dot group 14. The light spot ◯ is a groove dot group 14 arranged so that the long side of the dot 12 is parallel to the Y axis. The dark spot ● is a groove dot group 14 arranged so that the long side of the dot 12 is parallel to the X axis. The groove dot group 14 indicated by ◯ and ● is formed on the surface of the resin plate 10 which is the light guide plate on the + Z axis side (the back surface of the light guide plate). When light is incident at a certain spread angle from the end surface 10b of the resin plate 10 which is the light guide plate toward the + X axis direction and the resin plate 10 which is the light guide plate is observed from the −Z axis direction (front surface side), the light is emitted. The groove dot group 14 indicated by the point ○ appears to shine strongly, whereas the groove dot group 14 indicated by the dark point ● hardly appears to shine, so that the observer recognizes an arrow pointing in the + X-axis direction.

Similarly, when light is incident from the end face 10c toward the + Y-axis direction at a certain spread angle and the resin plate 10 which is the light guide plate is observed from the −Z-axis direction (front surface side), the groove dots indicated by the dark spots ● are observed. The group 14 appears to shine strongly, whereas the groove dot group 14 indicated by the light spot ◯ hardly appears to shine, so that the observer recognizes an arrow pointing in the + Y-axis direction. From the above, the resin plate 10, which is a light guide plate with a pattern design as shown in FIG. 14, controls the lighting and extinguishing of the light incident from the end face 10b and the end face 10c, so that the direction to be indicated is indicated as necessary. It can be used as a turn signal board that can be changed (see FIG. 15).

Even if the pattern is designed with the groove dot group 14 composed of dots 12, it is possible to create a light guide plate that can switch the display contents, but by devising the shape of the dots, the quenching ratio of the emission pattern is improved. , Visibility can be improved. 16 to 19 are diagrams showing the shape of dots 15 formed in a mold for creating a light guide plate with improved visibility and a method for creating the dots 15. The method of irradiating the laser beam 3 by moving the light-collecting spots 7 so as to partially overlap each other is the same as the method of forming the dots 8 described with reference to FIG. On the other hand, the power of the laser beam 3, the pulse width, the period of the pulse, and the moving speed of the focused spot 7 are not constant, and in the vicinity of the positions 15a at both ends of the dot 15 shown in FIG. It is adjusted so that the thermal influence of the above is small, and the thermal influence on the periphery is large except in the vicinity of the positions 15a at both ends. FIG. 17 is an enlarged sectional view taken along the line GG of the dot 15 of FIG. At this position, the laser beam 3 is adjusted and irradiated so as to have a large thermal effect on the periphery, so that a large burr 15b is formed. FIG. 18 is an enlarged cross-sectional view taken along the line HH of the dot 15 of FIG. At the positions at both ends, the laser beam 3 is adjusted and irradiated so as to reduce the influence of heat on the periphery, so that only a small burr 15c is formed. FIG. 19 is an enlarged cross-sectional view taken along the line I—I of the dot 15 of FIG. In the vicinity of both ends, the heat effect on the periphery of the laser beam 3 is adjusted to be gradually reduced, so that the burrs are also gradually reduced.

When the substrate 2 on which the dots 15 are formed is used as a mold and press molding is performed by the method described with reference to FIG. 6, the dots 16 shown in FIG. 20 are formed on the resin plate 10 which is the light guide plate. As shown in FIG. 20, the groove 16a formed by the burrs of the dots 15 has an oval shape, but the depth thereof varies greatly depending on the location. FIG. 21 is an enlarged cross-sectional view taken along the line JJ of the dot 16 of FIG. 20, and the groove 16a becomes shallow due to the action of the small burr 15c. FIG. 22 is an enlarged cross-sectional view taken along the line KK of the dot 16 of FIG. 20, and since the small burr 15c also acts on the dot 16, the groove 16a becomes shallow. FIG. 23 is an enlarged cross-sectional view taken along the line LL of the dot 16 of FIG. 20, and since the burr shown in FIG. 19 acts on the groove 16a, the groove 16a has a deep central portion and gradually becomes shallow in the vicinity of both ends. Comparing FIGS. 21 and 8, the area of the groove 16a that contributes to diffusion when light is incident parallel to the long side of dot 16 is diffused when light is incident parallel to the long side of dot 12. It can be seen that it is much smaller than the area of the groove 10a that contributes to.

On the other hand, comparing FIGS. 23 and 10, the area of the groove 16a that contributes to diffusion when light is incident perpendicularly to the long side of the dot 16 is such that the light is incident perpendicularly to the long side of the dot 12. It can be seen that the area of the groove 10a, which sometimes contributes to diffusion, decreases at both ends, but does not decrease significantly. That is, the ratio of the diffused light intensity when the light is incident parallel to the long side of the dot 16 and when the light is incident in the vertical direction is significantly larger than that of the dot 12. Therefore, in the light guide plate in which the groove dot group 14 is formed by using the dots 16 instead of the dots 12 and the pattern is designed, the extinction ratio of the light emitting pattern is improved and the visibility is improved.

(1) Laser Machining Machine A commercially available Yb fiber laser marker was used to form processing marks on the substrate surface 2a in the process of producing a mold. The laser is a pulse oscillation on the order of nanoseconds, and the oscillation wavelength is 1060 nm. The laser marker contains a laser oscillator 1, an X-axis mirror 4, a Y-axis mirror 5, and an fθ lens 6, and the power, pulse width, pulse period, and focusing of the laser beam 3 emitted from the laser marker. The position, movement locus, and movement speed of the spot 7 were set by a computer connected to the laser marker.

(2) Substrate Material As the substrate 2, a commercially available SUS304 stainless steel plate having a surface polished to # 400 was used.
(3) Resin plate material As the resin plate 10 to be the light guide plate, a commercially available acrylic resin plate having a total light transmittance of 93% was used.
(4) Light guide plate molding machine In the process shown in FIG. 3, the light guide plate was molded using a commercially available heat press machine.

(5) Composition of dot group The groove dot group 14 is composed of five dots 12 having an oval shape in a planar shape, 14a is about 350 μm, and 14b is 480 μm.

(6) Measurement of Diffusion Intensity Ratio A test piece was prepared in which a plurality of groove dot groups 14 were formed on a resin plate 10 to be a light guide plate with the directions of the long sides of the dots 12 aligned in the same direction. The test piece is a flat plate having a length of 30 mm, a width of 30 mm, and a thickness of 3 mm. The LED light was irradiated from the end face of the test piece in a direction perpendicular to the long side of the dot 12, and the brightness of the surface of the test piece was measured with a commercially available luminance meter. Similarly, an LED light having the same amount of light was irradiated from the end face of the test piece in a direction parallel to the long side of the dot 12, and the brightness of the surface of the test piece was measured with a luminance meter. As a result, the brightness when irradiated in the direction perpendicular to the long side was about 10 times the brightness when irradiated in the parallel direction.

(7) Prototype of a direction indicating plate capable of changing the direction to be instructed A test body was prepared by designing a pattern as illustrated in FIGS. 14 and 15. The test piece is a flat plate having a length of 30 mm, a width of 30 mm, and a thickness of 3 mm. FIG. 24 is a photograph of the surface of the test piece when the LED light 17, which is a floodlight, is irradiated from the left end face to the right. This corresponds to the case where the resin plate 10 is observed from the −Z axis direction by injecting light from the end face 10b toward the + X axis in FIGS. 14 and 15, and the groove dot group 14 indicated by ○ shines strongly. Since the light emission of the groove dot group 14 shown by ● is very weak, as shown in FIG. 24, an arrow pointing to the right is clearly recognized. FIG. 25 is a photograph of the surface of the test piece when the LED light 18 of the floodlight, which emits light downward from the upper end face, is irradiated. This corresponds to the case where the resin plate 10 is observed from the −Z axis direction by injecting light from the end face 10c toward the + Y axis in FIGS. 14 and 15, and the groove dot group 14 indicated by ● shines strongly. Since the light emission of the groove dot group 14 indicated by ◯ is very weak, a downward arrow is clearly recognized as shown in FIG. 25.

INDUSTRIAL APPLICABILITY The present invention can provide a method for inexpensively mass-producing a light guide plate having a function of switching display contents in an application in which the light guide plate itself is used as a display plate.

1 Laser oscillator 2 Substrate (mold)
2a Substrate surface 3 Laser light 4 X-axis mirror 5 Y-axis mirror 6 fθ lens 7 Condensing spot 8 Dots on the substrate 8a Burr (convex part) on the substrate
8b Recess on the substrate 9 Stage 10 Resin plate (light guide plate)
10a Fine groove on resin plate (V-shaped cross section)
10b End face of resin plate 10c End face of resin plate 11 Judge 12 Dots on resin plate 13 Light incident on resin plate 14 Groove dot group on resin plate 14a Length from end to end of groove dot group 14b Groove dot group Length of the long side of 15 15 Dots on the board 15a Positions of both ends of the dots on the board 15b Large burrs (convex parts) on the board
15c Small burrs on the substrate 16 Dots on the resin plate 16a Grooves on the resin plate (V-shaped cross section)
17 Rightward incident floodlight (LED light)
18 Downward incident floodlight (LED light)
AL, BL incident light MA, MB Group arrangement pattern of groove dot group

Claims (4)

A light guide plate is used as the panel plate of the display panel, and by injecting light that is 90 ° different in the incident direction from the end face of the light guide plate, it is represented on the surface of the light guide plate by a large number of light spots that are different in the incident direction of the light. It is a display panel that can display the displayed image.
For each of the two incident lights AL and BL having different 90 ° incident directions from the end face of the light guide plate, V-shaped grooves having a minute length extending in a direction orthogonal to the incident direction are formed at minute intervals. In addition, a large number of two types of groove dot groups formed by providing a plurality of rows in parallel are provided in a predetermined region on the back surface of the light guide plate, and the position where the groove dot group is provided is represented by the incident light of the display image. The configuration is such that the group arrangement patterns MA and MB are arranged so that they are the positions of the light spots.
When the incident light AL and BL on the end surface of the light guide plate are incident on a predetermined region on the back surface of the light guide plate while being totally reflected between the front surface and the back surface of the light guide plate, the incident light AL is orthogonal to the incident direction. The groove dots extending in the direction of light are reflected and diffused on the groove surface of the V-shaped groove with a minute length, and radiated from the surface of the light guide plate to visualize the groove dots as light spots. A display image can be expressed as a collective image of light spots due to incident light, and a cross section V with a minute length of another groove dot group extending in a direction orthogonal to the incident light even for incident light BL different by 90 °. By reflecting on the groove surface of the character groove and visualizing the groove dot group as light spots, a display image with a different pattern is displayed as a collective image of light spots, and further, minute amounts on the side parallel to the incident light. A display panel capable of displaying different display images depending on the incident direction of light, in which a group of groove dots having a length is not reflected and is not visible and becomes a dark spot so as not to affect the display of the different display images. In the same groove dot group, among a plurality of rows of V-shaped grooves having a minute length extending in a direction orthogonal to the incident direction, the groove ends of the V-shaped grooves having a front and rear cross sections are connected by a V-shaped groove to form a V. The first aspect of the present invention, wherein the planar shape of the character groove is an oval shape, and a plurality of rows of V-shaped cross-sectional V-shaped grooves having the elliptical shape in the planar shape are formed in the groove dot group in the incident direction. A display panel that can display different display images depending on the incident direction of the light. A display panel forming a V-shaped cross section in the groove dot group arranged in large numbers on the back surface of the light guide plate of the display panel capable of displaying different display images depending on the incident direction of the light according to claim 1 or 2. It is a manufacturing method of
A mold is formed by irradiating the surface of the substrate to be a mold with a laser beam so as to form a V-shaped groove in the cross section in the groove dot group, and forming a processing mark having a concave inside and a convex portion of a burr on the outer periphery. Next, the created mold is pressed against the resin plate to be the light guide plate at room temperature or in a state where the resin plate is softened by heating to the extent that the resin plate does not have fluidity, and the cross section V is processed against the resin plate. A method for manufacturing a display panel, which forms a character-shaped groove, and forms a V-shaped groove in a group of groove dots on the back surface of a light guide plate to form a display panel by using the above method. It is characterized by forming dots consisting of oval grooves on the resin plate by adjusting the pressure and pressing the mold against the resin plate to act on the convex parts of the mold while reducing the action of the concave parts. 3. The method for manufacturing a display panel according to claim 3.

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