JPH04234786A - Composite irregular reflection pattern for edge light panel - Google Patents

Abstract

PURPOSE:To offer a composite irregular reflection pattern for an edge light panel in which the uniformity of the illuminating brightness of a surface light source device is improved. CONSTITUTION:When virtual sections A-D are set on the surface of the edge light panel, the virtual section C obtains standard brightness by a light source 6, so that the area ratio of an increase-change pattern in the separation direction of a dot in the C is used as a standard, to arrange similar increase-change patterns that the area ratio is reduced in the A, and increased on the B and C. Thus, the irregular reflection of incident light is suppressed or promoted, and the brightness of each part is approximate to the standard brightness of the C, so that the uniformity is improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a composite of edge light panels that are formed by printing or other means on edge light panels of various surface light source devices such as liquid crystal bag lights, display stands, illuminated signs, display boards, and illumination bodies. Concerning diffuse reflection patterns.

0002

[Prior Art] A surface light source device uses an edge light panel in which a diffused reflection surface is formed on a transparent substrate with excellent translucency such as acrylic, and a primary light source such as a fluorescent lamp is arranged on one or more sides of the edge light panel. It is put into practical use as a backlight, etc.

[0003] The problem with this surface light source device is to obtain uniform and bright luminance, and for this reason, the present inventors have also proposed, for example, Japanese Patent Laid-Open Nos. 63-62104 and 2-126.
We are making proposals such as No. 501.

[0004] In these proposals, the diffuse reflection surface is formed by screen printing to expose fine halftone dots whose area ratio increases in the inward direction of the separation plane of the edge light panel from the primary light source. It is designed to promote in-plane diffuse reflection.

[0005]

[Problem to be solved by the invention] These are extremely effective in obtaining uniform and bright brightness, but they are not suitable for devices that are installed built-in to other equipment, such as LCD backlights, which are currently a typical application. For example, an edge light panel with a thickness of about 2 to 3 mm may be used as a single plate.

[0006] In such severe conditions, non-uniformity may still be observed on the illumination surface. This non-uniformity can appear as a brightness difference of 30% or more, with the area near the primary light source being slightly brighter and the surrounding area being slightly darker. It is necessary to improve uniformity.

The present invention has been made in view of the above problems, and its object is to provide a composite diffused reflection pattern for an edge light panel with improved uniformity as much as possible.

[0008]

[Means for solving the problem] In line with the above objective, as a result of intensive research, we have found that when a primary light source is incident on this type of edge light panel, the incident light tends to travel from the longitudinal middle of the light source side to the left and right inclined directions, respectively. Because of the strong It was found that the object becomes somewhat dark as it deviates from the traveling course, and that the lower left and right ends are near the ends of the primary light source and are easily affected by the darkness of those ends.

[0009] The present invention has been made based on such knowledge, and after virtual partitioning of these non-uniform parts caused by the primary irradiation light, the incident light course part excluding the overlapping parts is set to a reference luminance. Then, in accordance with this reference brightness, the dot area ratio of the increase change pattern is relatively decreased or increased as a brightness adjustment means in high brightness areas and low brightness areas, respectively.

That is, the present invention provides an inverted triangular or inverted building whose end on the primary light source side is defined by a triangular virtual section A whose base is an intermediate portion in the longitudinal direction of the light source side, and an extended hypotenuse imaginary line of the virtual section A. A pair of non-light source sides, where the left and right side sections of these virtual sections A and B are divided into a primary light source side and a non-light source side by an inclined virtual line pointing laterally from the midpoint of the hypotenuse side of virtual section A. The pattern surface is roughly divided into slanted virtual sections C, C and a pair of fallen building-shaped virtual sections D, D on the primary light source side, and steplessly in the light source separation direction in the virtual sections C, C. Based on an increase pattern in which the halftone area ratio is increased, a similar increase pattern in which the area ratio is relatively decreased is applied to virtual section A, and virtual sections B, D, and D are created.
The above object is achieved by relating to a composite diffused reflection pattern of an edge light panel, which is characterized by arranging similar increasing change patterns with relatively increased area ratios, and by making this the gist of the invention. It becomes a means of

The composite diffused reflection pattern of the present invention can be conveniently made into an edge-light panel by screen printing on a transparent substrate because extremely high precision results can be obtained. It is also possible to use a method such as adhering a film or shot blasting through a perforated plate.

[0012] For example, when using screen printing, the virtual divisions are set by measuring the brightness of the edge light panel at each location within the surface using a reference pattern (for example, a halftone dot pattern manufactured by Letra Japan), or by using this reference pattern. This can be done by simulating it on a computer.

[0013] Once the virtual sections have been set, a second original plate with adjustments made thereto is created, and each PVA film for printing is created by ultraviolet light exposure using this second original plate, and a screen is formed according to, for example, the above-mentioned Japanese Patent Laid-Open Publication No. 2-126501. Enable printing.

[0014] The second original plate is created by laminating a polyester milky white film on the original plate of the reference pattern and photographing it using, for example, a box-type photographing device. A masking method in which, for example, a milky white film similar to the above is partially interposed between the pattern original plates so that the light box light passes through as it is when decreasing the area ratio, and weakens the light when increasing the area ratio. This can be done relatively easily by using . This is because the area through which the light passes goes around the halftone dots of the original film and reaches the camera, so it is photographed and recorded on the second master film with a reduced halftone dot area ratio.
This is because masked areas do not have this phenomenon and are photographed and recorded so that the area ratio increases accordingly. Desired adjustments can be made by devising the layout, repeating photography, or applying this to each virtual section as necessary.

[0015] Of course, when using a computer,
In this way, it is sufficient to design a composite diffuse reflection pattern that is directly adjusted to each virtual section.

The range and size of the virtual section are not always the same and vary depending on factors such as the type of primary light source, brightness, the presence or absence of brightness variation, the size of the transparent substrate, and the means for forming the diffused reflection pattern. , the shape of the virtual partition may also partially change, and the area ratio should be adjusted to accommodate these changes.

[0017] The standard A4 size rectangular diffused reflection pattern is screen printed, and one end of the short side is made into a tube shape such as a fluorescent lamp or cold cathode tube, and a 12,000 nit
When using a single primary light source, adjustment of this area ratio is as follows:
In general, by decreasing or increasing this in the range of several to 20%, it is possible to obtain a brightness that is preferably as uniform as possible.

[0018] When using a relatively large edge light panel or when there is sufficient space for a single device, it is possible to provide a pair of primary light sources to supply incident light from multiple end faces. , it is also possible to set virtual sections from the ends of each primary light source. In this case, if the brightness increases due to overlapping and becomes non-uniform, the present invention may be applied to one of the light sources, and measures similar to the present invention may be applied to the other light source.

[0019] Furthermore, when an edge light panel of, for example, A4, B4, or B5 is made vertically long and a single primary light source is used on its short side, a decrease in brightness may be observed on the non-light source side of virtual section B. However, if the present invention is applied and such a phenomenon is observed, the non-light source side of virtual section B is set as another virtual section, the halftone area ratio is maximized, and this area ratio is Favorable uniformity can be obtained by continuing as it is to the non-light source side. Generally, the end face on the non-light source side is given a mirror finish and a reflective tape is attached to suppress the emission of incident light and improve the brightness by reflected light. Most of the light is actively utilized for uniform surface illumination, and the amount of light emitted can be reduced as much as possible, making it possible to omit the use of the above-mentioned mirror finish, reflective tape, etc. In this case, it is particularly preferable to adjust the maximum area ratio to about 50 to 60% or less.

[0020] On the sides of the transparent substrate, mirror-finishing the end faces can promote reflection of incident light in the in-plane direction, and finishing without mirror-finishing can reduce the amount of light incident from the end faces. Since it is possible to prevent an increase in brightness due to reflected light by emitting light, and such measures can also be taken by attaching a reflective tape to the end surface, these measures are adopted as auxiliary adjustment means of the present invention. You may.

[0021]

[Operation] In the present invention, since the virtual section C exhibits a brightness according to the incident light of the primary light source, the virtual section A has a relatively reduced area ratio, so that the incident light at that part is reduced. The brightness of the virtual sections B, D, and D is adjusted to decrease by suppressing the illumination brightness caused by diffused reflection and promoting the progress of the incident light. In addition to promoting diffused reflection, it also contributes to the progression of the incident light and adjusts the brightness in the direction of improving it.As a result, the edge light panel approximates the illumination brightness according to the incident light and works to improve uniformity. .

[0022]

[Embodiment] The present invention will be further explained below using an example of a liquid crystal backlight that illuminates the liquid crystal display surface of a laptop computer, word processor, television receiver, etc. In the figure, 1 is on the back side of the liquid crystal display surface. 2 is an edge light panel having a composite diffused reflection pattern 4 on the back side of a rectangular transparent substrate 3; 5 is this edge light panel 2;
A light reflection sheet made of a white polyester film is placed on the back side of the edge light panel 2, and 6 indicates a tube-shaped primary light source such as a fluorescent lamp or a cold cathode tube placed close to the end face of the edge light panel 2.

The light diffusion sheet 1, the edge light panel 2, and the light reflection sheet 5 each have the same shape, and are laminated and held in a frame and fixed to the case of the liquid crystal display device, and the primary light source 6 is also used. This is fixed to the case together with the inverter that operates it, and is used as a built-in device in the computer or the like.

Since this example is built into another device, the transparent substrate 3 of the edge light panel 2 is made of a single relatively thin piece with a thickness of 2 to 3 mm to make it especially compact. The light diffusion sheet 1 has a thickness of 75 μm, and the light reflection sheet 5 has a thickness of 188 μm.

The transparent substrate 3 is of a size approximately equivalent to B5, and a diffuse reflection pattern 4 is placed on the back side (lower surface in FIG. 1) over the entire surface so as to leave the outer periphery. It is printed and formed by screen printing using a white light density ink of No. 2-126501. In this example, the end surfaces of the transparent substrate 3 on the primary light source 6 side and on both sides thereof are polished to a mirror surface to increase the incident efficiency of the primary light source 6 and the reflection efficiency on the side surfaces. However, the end face on the non-light source side, which faces the end face on the primary light source 6 side, is subjected to normal finishing treatment without expecting reflection efficiency.

In this example, the composite diffused reflection pattern 4 changes the area ratio in a stepless manner from the edge of the primary light source 6 toward the inward plane of the separation plane, for example, as modeled in FIGS. 3 and 4. 1
A fine halftone dot pattern whose increase is in the range of 0% to 60% is used as a reference pattern.

At this time, the entire composite diffused reflection pattern 4 is divided into virtual sections A to G in this example, and predetermined brightness adjustment is performed.

That is, the effective irradiation surface of the primary light source 6 is 52.5° from both ends (boundary with the base) and 57.5° from the center.
If each pair of inclined imaginary lines 41 are set as a standard toward the other side edge, the incident light from the primary light source will be approximately contained in each pair of band-shaped inclined imaginary lines 41. It can be seen as progressing.

At this time, a triangular imaginary section A is set, which is surrounded by the above-mentioned imaginary lines 41 and has a base at the middle part in the longitudinal direction of the end side of the light source, in which the overlapping portion of the incident light occupies the majority, and A section including a triangular part symmetrical to this virtual section A, that is, the non-light source side of an inverted triangle whose end on the primary light source 6 side is divided by the hypotenuse extension virtual line 41 of the virtual section A. By further adding a transverse band-like part to the area, a virtual section B having an inverted building-like pentagon is set. Then, the left and right side sections of these virtual sections A and B are divided into a light source side and a non-light source side by an inclined virtual line 42 extending from the middle position of the hypotenuse side of virtual section A toward the side edge, respectively. Virtual divisions, that is, virtual divisions C and C on the traveling portion of the incident light excluding virtual division A, and a pair of collapsed building-shaped virtual divisions D and D on the light source side are set, and further,
A virtual section E with a low width bulge in the in-plane direction so as to straddle virtual sections B and C on the left and right end sides, and a virtual section with a transverse band shape toward the non-light source side of virtual section B. F and G are set respectively.

These virtual sections A to G can be experimentally obtained by determining the boundaries of the brightness difference portions that occur in the edge light panel based on the reference pattern.

In the virtual sections A to G set in this way, A has a relatively high brightness due to the polymerization of the incident light, and B receives some of the incident light in a straight line, but the propagation tendency of the light is As mentioned above, the brightness tends to be low because it depends mainly on the reflected light, and since C and C are in the traveling part of the incident light, the brightness that most closely matches the incident light can be obtained.
Compared to A, the brightness must be lower, and D, D
In the longitudinal direction illumination brightness of the fluorescent lamp or cold cathode tube of the primary light source 6, the brightness mainly depends on reflected light due to variations in brightness such that the ends are dark, and due to the presence of the primary light source base set. Therefore, like B, it tends to decrease.

Furthermore, the brightness of E and F decreases when they are separated from the primary light source 6, and when the end surface of G is mirror-finished, the reflected light conversely concentrates and the brightness decreases. There is a tendency to improve.

In the above brightness adjustment, the brightness of the virtual sections C and C that best reflects the incident light of the primary light source 6 is set as the standard brightness, although the brightness is lower than that of the above A, and this is used as the reference brightness, and other brightnesses are adjusted. We are trying to approximate this as much as possible.

That is, in the virtual section A, the increasing change pattern in which the halftone dot area ratio is steplessly increased in the light source separation direction in the halftone dot pattern portion appearing in the virtual sections C and C is used as the reference pattern. , by relatively decreasing the area ratio, the diffused reflection of the part is suppressed, and on the other hand,
In virtual sections B, D, and D, the basic measure is to relatively increase this to promote diffused reflection.

Furthermore, the brightness adjustment of the virtual section E is carried out by polishing the side end surfaces to a mirror surface and reflecting the incident light as much as possible within the surface, thereby improving the relative brightness. It is kept inconspicuous.

In the virtual sections F and G, in F, the maximum area ratio of the halftone dot pattern is arranged in the virtual section, and this is the part where diffused reflection is most promoted. The same maximum area ratio part as F is continued as it is, and the most promoted diffused reflection is continued as it is in that part, thereby making use of the incident light as much as possible in G and improving uniformity. At the same time, reflective measures on the non-light source side end face are omitted.

Note that the virtual sections F and G, which constitute the maximum area ratio in this example, abut each other toward the non-light source side while maintaining an area ratio of approximately 60%, as shown schematically in FIG. 4, for example. Also, the left and right sides are arranged in rows with a small distance from each other. For example, 70
When the area ratio is increased to % or more, sideways running bright lines may appear due to excessive diffuse reflection due to overlapping halftone dots.In addition to preventing this, This can be seen as a result of leaving a path for the incident light, but it is a favorable result in terms of overall uniformity and brightness.

As shown in the figure, when the primary light source is placed at one end and the edge light panel is made vertical, the light source is placed at both ends, or when placed at one end but made horizontally long. Although the tendency for non-uniformity to occur increases, according to experiments, when the average luminance of virtual sections C and C is 150 nits, virtual section A has an area ratio of 80% of the area ratio of C, and virtual section B has an area ratio of 110 nits. %, and virtual section D is approximately 120%, the brightness in these virtual sections A to D is ±
The difference is within about 10% of 15 nits, making it possible to make the liquid crystal backlight almost inconspicuous.

Although this example has been constructed as described above, it will be clear to those skilled in the art from the above description and examples that the present invention can be applied to a surface light source device other than a liquid crystal display panel, and that edge light panels can be stacked. Specific structures such as surface light source devices, edge light panels, composite diffused reflection patterns, each virtual section and its area ratio, materials, dimensions, configuration or shape means, including configuring it into a curved surface, etc. Additional measures, etc. may be variously changed as necessary as long as they do not go against the gist of the invention described above, and are not necessarily limited to those shown or explained.

[0040]

[Effect of the invention] Since the present invention is configured as described above,
By using the brightness obtained by the incident light as the standard brightness, it is possible to adjust the non-uniformity that occurs in other parts to approximate this brightness, so the difference in brightness between each part can be easily reduced and the uniformity can be improved as much as possible. This makes it possible to provide a composite diffused reflection pattern for an edge light panel that can provide unnoticeable uniform illumination even under severe conditions.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a liquid crystal backlight.

FIG. 2 is a plan view showing virtual sections of an edge light panel.

FIG. 3 is a plan view showing an example of a halftone dot pattern.

FIG. 4 is a plan view showing an example of a halftone dot pattern.

[Explanation of symbols]

1. Light diffusion sheet 2 Edge light panel 3 Transparent substrate 4 Composite diffuse reflection pattern 5. Light reflective sheet 6 Primary light source 41 Virtual line 42 Virtual line

Claims (1)

[Claims] Claim 1: A triangular virtual section A whose base is the longitudinally intermediate portion on the primary light source side, and an inverted triangular or inverted building shape whose end on the primary light source side is defined by a hypotenuse extension virtual line of the virtual section A. A pair of inclined shapes on the non-light source side, where the left and right side sections of these virtual sections A and B are divided into the primary light source side and the non-light source side by inclined virtual lines that point laterally from the middle position of the hypotenuse side of the virtual section A. The pattern surface is roughly divided into virtual divisions C, C and a pair of collapsed building-shaped virtual divisions D, D on the primary light source side, and a mesh is created steplessly in the direction of separation of the light sources in the virtual divisions C, C. Based on the increase/change pattern in which the point area ratio is increased, a similar increase/change pattern in which the area ratio is relatively decreased is applied to virtual section A, and the area ratio is relatively increased to virtual sections B, D, and D. A composite diffused reflection pattern of an edge light panel is characterized in that it is formed by arranging similar increasing change patterns respectively.