JPH117261A - Both-side surface light source element and both-side display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a both-side surface light source element having high luminance and having the improved uniformity of the luminance distribution in a light emitting face. SOLUTION: The device is provided with a 1st element 12A for emitting light in a 1st plane side (direction A) and a 2nd element 12B for emitting light to a 2nd plane side (direction B). The 1st element 12A is constituted of a light source 2, a light guide body 4A whose side end face opposite to the light source 2 functions as a light incident face 22 and whose face orthogonal to the face 22 functions as a light emitting face 24, a light angle varying sheet 6A arranged on the light emitting face side of the light guide body 4A and a reflection film 8a sticking to a side opposite to the light emitting face of the light guide body 4A. The light emitting face 24 of the light guide body 4A is constituted of many lens arrays whose mean tilt angle is 0.5 to 25 deg. and which are parallel to the light incident face 22. The 2nd element 12B is constituted of the light source used in common to the 1st element 12A, a light transmission body 4B, a light angle varying sheet 6B and a reflection film 8B, and the constitution of the 2nd element 12B is equivalent to that of the 1st element 12A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source element and a surface light source element constituting a signage device such as a guide signboard or a large signboard at a station or a public facility, or various guide signs or traffic signs on an expressway or a general road. More particularly, the present invention relates to a double-sided light source element having high luminance and capable of obtaining a uniform luminance distribution in a light emitting surface, and a double-sided marking device using the same. .

[0002]

2. Description of the Related Art In a signing device such as a guide signboard or a large signboard, or a signage device such as a guide sign or a traffic sign on an expressway or a general road, night visibility and legibility are required. In order to enhance the lighting efficiency, two illumination systems, an internal illumination system and an external illumination system, are employed. In the internal lighting system, characters, figures, photographs, etc. are formed on a translucent plastic plate such as a methacrylic plate by cutting or printing to form a sign board (marking element), and a light source is arranged inside the sign board. The sign plate is illuminated by a light source, and a straight tube or ring-shaped fluorescent lamp is generally used as the light source. In the external lighting system, a light source is arranged above, below, and on the front side of the sign board on which the sign contents are formed, and the light source illuminates the entire surface of the sign board. Tube-shaped fluorescent lamps are commonly used.

In such a conventional sign device, the luminance distribution over the entire surface of the sign plate becomes non-uniform, that is, the maximum / minimum luminance value becomes extremely large. It was difficult to obtain a sign device having high uniformity and high brightness. This tendency was particularly remarkable in the external lighting system. In addition, the internal lighting system has a problem that a see-through phenomenon occurs in which a fluorescent lamp or the like used as a light source can be seen through a sign board.

[0004] By the way, as a marking device, a device that performs marking on both sides is increasingly used.
In such a double-sided marking device, an internal illumination system is often adopted from the viewpoint of effective use of a light source. In this case, in order to avoid the above-mentioned problem, it is necessary to increase the distance from the light source to the sign board to increase the distance between the sign boards on both sides. That is, in order to improve the uniformity of the luminance distribution and avoid the see-through phenomenon, the thickness of the marking device has to be increased. This goes against the demand for a thin display device.

Accordingly, an object of the present invention is to provide a double-sided light source element having high luminance and excellent uniformity of luminance distribution in a light emitting surface. Another object of the present invention is to provide a double-sided marking device that can be made thin using such a double-sided surface light source element.

[0006]

Means for Solving the Problems In view of the situation described above, the present inventors have made intensive studies on the structure of the light emitting surface of the light guide or the back surface thereof, and have found that the light emitting surface or the back surface has a specific average. By providing a rough surface with a fine uneven shape with a tilt angle or a fine uneven surface with a large number of lens rows, it has high brightness and excellent uniformity of the brightness distribution of emitted light within the light emitting surface. The present inventors have found that a double-sided surface light source element can be obtained and arrived at the present invention.

That is, according to the present invention, a first element for emitting light to the first surface and a light to the second surface opposite to the first surface are provided to achieve the above objects. And a second element for emitting light. The first element and the second element each have a light source, and at least one side end face facing the light source is a light incident surface, and is substantially orthogonal to the light incident surface. 1
A light guide having one surface as a light exit surface, and a light bending sheet disposed on the light exit surface side of the light guide, and at least one of a light exit surface of the light guide and a back surface thereof. The surface has a fine structure with an average inclination angle of 0.5 to 25 °, and the first
A double-sided light source element is provided, wherein the element and the second element are arranged such that the back surfaces of the light guides face each other.

According to the present invention, in order to achieve the above object, a light source and at least one side end face facing the light source are provided as a light incident surface, and two light sources which are substantially orthogonal to the light incident surface are provided. A light guide whose surfaces are light exit surfaces on a first surface side and a second surface side, and first and second light modulators disposed on the first surface side and the second surface side of the light guide, respectively. Consisting of square sheets,
A double-sided light source device, wherein at least one of the first surface side and the second surface side of the light guide has a fine structure with an average inclination angle of 0.5 to 25 °. Provided.

Further, according to the present invention, the first and second transmissive display elements are arranged on the first and second surfaces of the double-sided light source element as described above. A double-sided marking device is provided.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a double-sided light source device according to the present invention.
It is a fragmentary perspective view which shows embodiment.

As shown in FIG. 1, the surface light source element of the present invention has a first element 12A and a second element 12B. Reference numeral 2 denotes a light source elongated in the CD direction. The light source may be shared by the first element 12A and the second element 12B as shown, or separate light sources may be arranged at respective ends of the first element 12A and the second element 12B. Is also good. In addition, whether the light sources are shared or individually arranged, they may be arranged at one end of the first element 12A and the second element 12B, or may be arranged at both opposing ends.

The first element 12A includes a light guide 4A having at least one light incident surface 22 facing the light source 2 and a light exit surface 24 substantially orthogonal thereto, and a light guide 4A mounted on the light exit surface 24 of the light guide 4A. A light bending sheet 6A made of a lens sheet such as a prism sheet placed thereon, and a reflection film 8 having a reflection surface provided on a back surface opposite to the light emission surface 24 of the light guide 4A.
A.

The second element 12B has the same structure as the first element 12A, and has at least one light incident surface facing the light source and a light guide 4B having a light exit surface substantially orthogonal to the light incident surface.
A light-deflecting sheet 6B made of a lens sheet such as a prism sheet placed on the light-emitting surface of the light guide 4B, and a reflection surface provided on the back surface facing the light-emitting surface of the light guide 4B. And a reflection film 8B.

The first element 12A and the second element 12B are arranged adjacently so that the reflection films 8A and 8B face each other. In the following, the first element 12A
The above description also applies to the second element 12B except for the orientation of the array.

In such a double-sided surface light source element, the light guide 8 having a component in the F direction from the light source 2 passes through the light incident surface 22.
The light incident into A propagates through the light guide 4A by repeating reflection (including total reflection) on the light exit surface 24 of the light guide 4A, its back surface, or the reflection film 8A attached to the back surface. . When irregularities are formed on the surface (light emitting surface 24) of the light guide 4A, of the light that has reached the irregularities, light incident at a critical angle or less with respect to the irregularities is refracted and out of the light guide 4A. And the light that enters at an angle exceeding the critical angle is totally reflected and propagates through the light guide 4A. This is because the traveling direction of light is determined by the refractive index of the medium and the angle of incidence of the light with respect to the normal to the incident surface according to Snell's law.

FIG. 2 schematically shows the refraction and reflection of light at the light guide 4A having an uneven surface. The light incident on the slope of the concavo-convex portion at an incident angle i within the critical angle is a light guide at an output angle i 'that satisfies the relationship of nsini = sini' (n is the refractive index of the light guide 4A) according to Snell's law. Emitted from 4A. On the other hand, light incident at an incident angle k exceeding the critical angle is
The light is totally reflected at an angle k ′ (k ′ = k) and propagates in the light guide 1. The light once incident on and reflected by the uneven portion changes its incident angle when it is subsequently incident on the uneven portion.
Outgoing light is produced. Some of the light incident on the smooth back surface 26 is incident at a critical angle or less, and the light exits the light guide 4A via the back surface 26. The emitted light is returned into the light guide 4A again by the reflection film 8A provided on the back surface 26.

In the surface light source element such as the first element 12A, the present inventors have found that the light emission intensity (I) at a certain point in the light emission surface 24 and the emission light intensity ( I ₀ ), the output rate (α) and the distance (L ′) from the edge of the light incident surface.
It was found that the following formula (1) was satisfied experimentally by the thickness (t) of the light guide 4A.

I = I ₀ (1−α / 100) ^{L ′ / t} (1) From equation (1), if the length (L) and thickness (t) of the light guide 4A are determined, It can be seen that the uniformity of the luminance distribution of the outgoing light in the light emitting surface 24 depends on the outgoing rate (α). The emission ratio (α) of the light guide 4A having the thickness t (mm) is equal to the light guide 4A.
The luminance is measured at an interval of 20 mm from the end of the light incident surface, and the distance (L ') from the end of the light incident surface and the thickness (t) of the light guide 4A are measured.
From the graph of the ratio (L ′ / t) to the logarithm of the luminance, the gradient (K (mm ⁻¹ )) is obtained, and is obtained by the following equation (2).

Α = (1-10^K ) × 100 (2) In the present invention, the following is a measure of the uniformity of the luminance distribution.
Using the degree of variation (R%) shown in equation (3),
Evaluation and uniformity of brightness distribution in light source element
And examination. The degree of variation (R%) depends on the light guide 4A.
Substantially at the center (in the longitudinal direction of the light source 2, that is, in the CD direction)
(Center) at a point 50 mm away from the edge of the light incident surface.
The brightness is measured at intervals of 50 mm within the range up to the opposite end.
The maximum value of the measured luminance (I_max), The minimum value of the measured brightness
(I_min), The average value of the measured luminance (I _av), The next
It is determined by equation (3).

[0021] _{R% = {(I max -I} min) / I av} × 100 ··· (3) As a result, the emission rate and the (alpha) and variation degree (R%), of the light guide 4A length It has been found that there is a specific relationship depending on the thickness (L) and the thickness (t). As the emission rate (α) increases, the degree of variation (R%) increases accordingly, and the emission rate (R) increases. If α) is constant, the degree of variation (R%) increases as the ratio (L / t) between the length (L) and the thickness (t) of the light guide 4A increases. That is, in the light guide 4A having a certain size, the uniformity (degree of variation) of the luminance distribution in the light exit surface 24 of the light guide 4A depends on the emission rate (α) from the light guide 4A. It has been found that uniformity of the luminance distribution can be achieved by controlling the emission rate (α).

On the other hand, the present inventors have proposed the case where the surface (light emitting surface 24) of the light guide 4A is constituted by a rough surface composed of a large number of fine irregularities, or the light incident surface 22 is formed on the surface of the light guide 4A. When a large number of lens arrays extending in a direction parallel to the direction of the arrow, ie, in the CD direction, are formed, the light emitted from the light guide 4A depends on the gradient of the unevenness forming the rough surface or the gradient of the inclined surface forming the lens array. It has been found that the emission direction and the emission rate change.
In the case of a rough surface having fine irregularities, it is considered that the fine irregular shape is a slope having approximately one slope. Here, an average inclination angle (θa) defined by ISO4287 / 1-1987 can be used as the gradient. When the average inclination angle (θa) increases, the light emitted from the light guide 4A becomes closer to the normal direction of the light emitting surface 24 (the thickness direction of the light guide 4A, that is, the AB direction). Further, as the average inclination angle (θa) increases, the emission rate (α) from the light guide 4A increases accordingly. Therefore, the uniformity of the luminance distribution in the light emitting surface 24 of the surface light source element can be increased by lowering the emission rate (α) from the light guide 4A, and the average inclination angle (θa) can be reduced. It has been found that uniformity can be achieved by reducing the size.

Further, the present inventors require a surface light source element used in a signage device such as a guide signboard or a large signboard if the degree of variation (R%) is 450% or less. It has been found that good luminance distribution uniformity can be satisfied, and for this, it is necessary to set the average inclination angle of the rough surface or the lens array to 25 ° or less.
The variation (R%) of the surface light source element used in the marking device is preferably 100% or less, more preferably 50% or less.

In the present invention, based on such new knowledge, the light exit surface 24 and the rear surface 2 of the light guide 4A are formed.
6 has an average inclination angle (θa) of 0.
By forming the surface with a rough surface of 5 to 25 °, preferably 0.5 to 7.5 ° or a large number of lens rows, the emission rate (α) from the light guide 4A can be sufficiently reduced. This makes it possible to achieve a uniform luminance distribution in the light exit surface 24 of the light source element. This is because if the average inclination angle (θa) is less than 0.5 °, the total amount of light emitted from the light exit surface 24 of the light guide 4A decreases, and sufficient luminance cannot be obtained, or the light exit surface The emission angle of the light emitted from the light-emitting surface 24 (the angle with respect to the normal line of the light-emitting surface 24) becomes large, and the emitted light can be sufficiently directed in the normal direction even when the light bending sheet 6A such as a prism sheet is used. It is because it disappears. Conversely, when the average inclination angle (θa) exceeds 25 °, the emission rate (α) of the light guide 4A increases, and the uniformity of luminance is impaired as a surface light source element for a sign device. Preferably, the average inclination angle (θa) is in the range of 1 to 5 °, more preferably in the range of 2 to 4 °.

Although the size of the light guide 4A is not particularly limited, the length (L) and the thickness (t) of the light guide 4A are required to make the effect of the present invention more remarkable. And the ratio (L
/ T) is preferably 200 or less. L / t is 20
If it exceeds 0, the uniformity of the luminance distribution in the light emitting surface tends not to be sufficiently achieved even if the average inclination angle (θa) of the rough surface of the light guide 4A or the lens array is reduced. . L / t
Is preferably 150 or less, more preferably 30 to 10
It is in the range of 0.

As the light guide 4A, a transparent plate made of glass, synthetic resin or the like can be used. As the synthetic resin, for example, an acrylic resin, a polycarbonate resin, various highly transparent synthetic resins such as a vinyl chloride resin can be used, and this resin is extruded by a normal molding method such as injection molding. The light guide 4A can be manufactured by forming it into a plate-like body. In particular, methacrylic resin is excellent in light transmittance, heat resistance, mechanical properties, and moldability, and is suitable as a light guide material. In particular, a resin having a methyl methacrylate unit content of 80% by weight or more is preferable as the methacrylic resin. In the light guide 4A, glass beads, inorganic fine particles such as titanium oxide, and resin fine particles such as a styrene-based resin, an acrylic resin, and a silicone-based resin can be dispersed as a light diffusing material.

The processing method for forming a fine structure having a specific average inclination angle (θa) on the light guide 4A is not particularly limited. For example, the rough surface is formed by chemical etching using hydrofluoric acid or the like. Pressing and injection using a mold made of metal or glass, etc., a mold roughened by blasting fine particles such as glass beads, a mold with a rough surface formed by using blast and chemical etching, etc. A method of transferring a rough surface by molding or the like, a method of applying or attaching a transparent substance to the light guide 4A in a concavo-convex shape by a printing method, etc .;
Is directly processed by a blast method, an etching method, or the like.

The fine structure to be formed on the surface of the light guide 4A is not particularly limited as long as the average inclination angle (θa) is 0.5 to 25 °. And a lens array having an arc-shaped lenticular lens, a lens array having a triangular to polygonal prism array, and the like. Such a lens array includes the light guide 4A.
The lens array is formed so as to extend in a direction parallel to the light incident surface 22. The pitch of the lens rows is appropriately selected depending on the application, but is usually preferably in the range of 20 μm to 5 mm.

As a processing method for forming a large number of lens rows having a specific average inclination angle (θa), for example, a metal or glass mold having a lens pattern formed by chemical etching, cutting tool, laser processing or the like may be used. A method of forming a transparent substrate by hot pressing or injection molding a transparent resin, applying an active energy ray-curable resin on the transparent substrate, and shaping and curing by irradiation with active energy rays. Transfer method, light guide 4
A method of directly processing A by etching, cutting tool, laser processing, or the like can be given.

In the surface light source element of the present invention, the light source 2 such as a fluorescent lamp is arranged adjacent to one end (incident end face 22) of the above-described light guide 4A, and faces the light emitting face 24. Back 2
6, a reflection film 8A having a reflection surface is arranged.

As shown in FIG. 3, in order to effectively introduce light from the light source 2 to the light guides 4A and 4B, the light incident surfaces 22 of the light source 2 and the light guides 4A and 4B are reflected inward. It can also be configured to cover with a case or sheet 10 coated with an agent. Note that the first element 12A and the second element 12B
As shown in FIG. 4, in the case of using a unique light source, in the first element 12A, the light source 2A and the light incident surface 22 of the light guide 4A are coated with a case or sheet 1 coated with a reflective agent.
0A, and the second element 12B covers the light source 2B and the light incident surface 22 of the light guide 4B with a case or sheet 10 coated with a reflective agent.
Cover with B. In this case, the light source 2A and the light source 2B may be arranged at ends opposite to each other in the EF direction (that is,
For example, the light source 2A is arranged at the end in the E direction as shown, and the light source 2B is arranged at the end in the F direction opposite to the illustration).

The light guides 4A and 4B are shown in FIGS.
As shown in FIG. 2, the light exit surface 24 and its back surface (2
Except for the surface microstructure of 6), a plate having an overall shape of a parallel plate can be used. Furthermore, a wedge shape as shown in FIG. 5 (thickness gradually decreases in the EF direction)
Can also be used. In this case, the first element 12A and the second element 12B can use one light source 2A and 2B, respectively, and can arrange these light sources at opposite ends in the EF direction. Thereby, the thickness of the double-sided light source element can be made uniform throughout. Alternatively, a material whose thickness gradually decreases toward the center at both ends in the EF direction can be used. In this case, in the first element 12A, the light sources 2A, 2A 'are arranged at both ends in the EF direction, and in the second element 12B, the light sources 2B, 2A' are also arranged.
2B 'are arranged at both ends in the EF direction. Light source 2A, 2
B can be shared, and the light sources 2A 'and 2B' can be shared.

In the surface light source element of the present invention, the light emitted from the light guide 4A normally has a directivity of 60 to 80 ° from the normal to the light exit surface 24. In order to change the angle of the emitted light in a specific direction such as the normal direction, a light changing sheet 6A is placed on the light guide 4A. In this case, examples of the variable optical angle sheet 6A include a diffusion sheet and a lens sheet having a lens surface having a large number of lens units formed in parallel on at least one surface. The emission direction of the light emitted from the light guide 4A is the light emission surface 24.
When the angle formed with respect to the normal line is large, a lens sheet having a lens surface in which a large number of lens units are formed in parallel is preferable. As the lens shape formed on the lens sheet, various shapes are used depending on the purpose, and examples thereof include a prism shape (see FIG. 7), a lenticular lens shape, and a corrugated shape. The pitch of the lens unit of the lens sheet is preferably about 30 μm to 2.0 mm. When a prism sheet is used, as shown in FIG. 7, the prism apex angle φ is appropriately selected according to the emission angle of the light emitted from the light guide. Preferably, it is in the range of 120 °. The inclination angles φ1 and φ2 formed by the first prism surface S1 and the second prism surface S2 sandwiching the apex angle of the prism (prism row) of the prism sheet with respect to the direction of the normal line N of the prism sheet are:
Can be set equal. However, these inclination angles φ
1 and φ2 can be set to be different from each other when the emitted light has directivity in a direction other than the direction of the normal line N. In that case, for example, φ1 is set to 5 to 45 °,
φ2 can be 15 to 85 °. However, when observing the sign board, it is rare to observe a direction extremely inclined with respect to the direction of the normal line N.
1 is 30 to 45 °, and φ2 is 35 to 50 °.

Also, the direction of the lens sheet is appropriately selected according to the emission angle of the light emitted from the light guide, and the lens sheet may be placed so that the lens surface is on the light guide side, or may be reversed. It may be mounted. Normally, when using the light guide 4A having a rough surface having the specific average inclination angle (θa) as described above or a surface constituted by a large number of lens rows, a prism sheet having a vertex angle of 40 to 80 ° Is placed so that the prism surface is on the light guide side, it is possible to make the emitted light substantially in the normal direction of the light exit surface 12 of the light guide. The prism apex angle of the prism sheet is preferably 50 to 75 °.

In the surface light source element of the present invention, a plurality of sheets of the variable optical angle sheet 6A can be used as required. For example, when two lens sheets are used, the two lens sheets can be stacked and used such that respective lens rows are at an angle or parallel to each other. The lens sheets can be placed so that each lens surface is in the upper or lower direction, and the lens surfaces of both lens sheets can be placed in the opposite direction. it can. In this case, in the surface light source element of the present invention, the first lens sheet adjacent to the light guide 4A is placed so that the lens surface is on the light guide side and the lens array is parallel to the light source.
Further, it is preferable that the second lens sheet is placed so that the lens surface is on the opposite side to the light guide, and the lens row is orthogonal to the lens row of the first lens sheet. When a prism sheet is used as the lens sheet, the first prism sheet has a prism apex angle of 50 to 75 °, and the second prism sheet has a prism apex angle of 80 to 100 °. Preferably, one is used.

The lens sheet is preferably manufactured using a material having a high visible light transmittance and a relatively high refractive index. For example, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, an active energy ray-curable Resins. Among them, an active energy ray-curable resin is preferred from the viewpoints of scratch resistance, handleability, productivity and the like of the lens sheet. Also, if necessary, the lens sheet
Additives such as antioxidants, ultraviolet absorbers, yellowing inhibitors, bluing agents, pigments, and diffusing agents can also be added.
As a method for producing the lens sheet, a usual molding method such as extrusion molding and injection molding can be used. When manufacturing a lens sheet using an active energy ray-curable resin, it is made of a transparent resin such as a polyester resin, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylimide resin, and a polyolefin resin. A lens portion is formed on a transparent substrate such as a transparent film or sheet using an active energy ray-curable resin. First, an active energy ray-curable resin liquid is injected into a lens mold having a predetermined lens pattern formed thereon, and a transparent substrate is overlaid. Next, an active energy ray such as an ultraviolet ray or an electron beam is irradiated through a transparent base material, and the active energy ray-curable resin liquid is polymerized and cured, and is separated from a lens mold to obtain a lens sheet.

In the surface light source element of the present invention, the light is optically deflected, focused, diffused, and its optical characteristics are changed, such as a diffusion sheet, a color filter, and a polarizing film, together with the lens sheet as described above. Various optical elements can be used. As the light source 2, a general straight tube type fluorescent lamp can be used, but when replacement of the light source 2 is difficult, the light source 2 is separately installed using a line light composed of a plurality of optical fibers. Light can also be transmitted from a light source.

The first element 12A thus constructed
And the second element 12B, the first surface side (the A direction side of the first element 12A) and the second surface side (the B element of the second element 12B).
As shown in FIG. 1, characters, figures, photographs, and the like are formed on a translucent plastic plate such as a methacrylic plate by cutting, printing, etc., as shown in FIG. The signing device such as a guide signboard or a large signboard in a station, a public facility, or the like is formed.

FIG. 8 shows a second embodiment of the double-sided light source device according to the present invention.
FIG. 4 is a partial cross-sectional view for describing the embodiment. In this figure, members having the same functions as those in FIGS. 1 to 7 are denoted by the same reference numerals.

In this embodiment, the reflection surface of the first element 12A and the reflection surface of the second element 12B are formed on the reflection film 8 as a common reflection member. Thereby, the number of components can be reduced.

FIG. 9 shows a third embodiment of a double-sided light source device according to the present invention.
FIG. 4 is a partial cross-sectional view for describing the embodiment. In this drawing, members having the same functions as those in FIGS. 1 to 8 are denoted by the same reference numerals.

In the present embodiment, the smooth back surface 26 of the light guide 4A of the first element 12A and the smooth back surface 26 of the light guide 4B of the second element 12B are provided without the interposition of the reflection surface.
Are arranged to face each other. As a result, as shown in FIG. 9, light incident on the back surface 26 from the light guide 4A side at an angle equal to or less than the critical angle immediately after the light exits the first element 12A.
Light that enters the element 12B and enters the back surface 26 from the light guide 4B side at an angle equal to or less than the critical angle immediately enters the first element 12A after exiting the second element 12B. According to the present embodiment,
Although light flows between the first element 12A and the second element 12B, the same operation and effect as when a reflecting surface is interposed between the first element 12A and the second element 12B are obtained. It can be obtained after reducing the score.

FIG. 10 is a partial sectional view for explaining a fourth embodiment of the double-sided light source element according to the present invention. In this figure, members having the same functions as those in FIGS. 1 to 9 are denoted by the same reference numerals.

In this embodiment, a single light guide 4 is used in which the light guide 4A of the first element 12A and the light guide 4B of the second element 12B of the third embodiment are integrated. Have been. That is, the light guide 4 has light emitting surfaces 24A and 24B formed on both the first surface side and the second surface side (that is, both side surfaces). The configuration of the light emitting surfaces 24A and 24B is the same as that of the light emitting surface 24. The light exit surfaces 24A, 2A
Only one of the light emitting surfaces 4B may have the same configuration as the light emitting surface 24, and the other may be, for example, a flat surface. According to this embodiment, the same operation and effect as those of the third embodiment can be obtained.

[0045]

The present invention will be described below with reference to examples.

In the following examples, the average inclination angle (θ
a) was obtained as follows according to ISO 4287 / 1-1987. That is, 010-2528 as a stylus
The surface roughness was measured at a driving speed of 0.03 mm / sec by a stylus type surface roughness meter (Surfcom 570A manufactured by Tokyo Seiki Co., Ltd.) using (1 μmR, 55 ° cone, diamond).
From the chart obtained by the measurement, to correct the inclination by subtracting the average line, the following (4) was calculated by - (5): Δa = (1 / L " ) ∫ 0 L" | ( d / dx) f (x) | dx (4) θa = tan ⁻¹ Δa (5) where L ″ is the distance scanned by the stylus, x is the measurement position, and f (x ) Represents the displacement of the stylus.

Example 1 The surface of a glass plate was made to have a particle size of 12
5-149 µm glass beads (Fuji Manufacturing Co., Ltd .: FG
B-120), blasting was performed at a distance of 10 cm from the glass plate to the spray nozzle and a spray pressure of 4 kg / cm ² . Thereafter, the blast surface is chemically etched by performing a hydrofluoric acid treatment, and 5 mm (thickness) is obtained using an electroforming mold obtained by forming a replica mold by electroforming.
The rough surface was transferred by heat transfer to one surface of a transparent acrylic resin plate of × 1200 mm × 800 mm to obtain a light guide. Two light guides were obtained. The average inclination angle (θa) of the rough surface of the obtained light guide was 2.0 °.

For each of the two light guides obtained, a PET film on which silver was vapor-deposited was adhered to one end face of 1200 mm and two end faces of 800 mm by adhesive treatment. Then, the two light guides are overlapped with each other so that the roughened light emission surfaces are located outside each other, and the 1200 mm end faces on which the silver-evaporated PET film is not attached correspond to each other. A combined body was obtained. At this time, PE with silver deposited between the back surfaces of the two light guides
A reflective surface was formed with a T film interposed.

A straight tube type fluorescent lamp (28 W, tube diameter 16 mm, tube length 1149 mm) was arranged adjacent to the 1200 mm end face on which the silver-evaporated PET film was not attached. Then, on the light emitting surface of each light guide, a prism sheet is formed by forming in parallel a number of prism rows of an acrylic UV curable resin having a refractive index of 1.53 on a PET film with a vertical angle of 63 ° and a pitch of 50 μm. Was mounted such that the prism surface faces the light emitting surface side of the light guide, to obtain a double-sided light source element. The average luminance in the normal direction of the obtained double-sided light source element is 8
At 20 Cd / m ² , the degree of variation (R%) was 110%.

A transparent acrylic resin plate on which a photograph was printed was placed as a transmission type display element on the prism sheet of the double-sided light source element obtained as described above, thereby producing a double-sided signboard. This double-sided signboard was bright and had good uniformity of luminance distribution.

Example 2 A double-sided surface was obtained in the same manner as in Example 1 except that a silver-deposited PET film was not interposed between the back surfaces of the two light guides when obtaining a light-guide superimposed body. A light source element was obtained. The average luminance in the normal direction of the obtained double-sided light source element was 1050 Cd / m ² , and the degree of variation (R
%) Was 103%.

A transparent acrylic resin plate on which a photograph was printed was arranged as a transmission type display element on the prism sheet of the double-sided light source element obtained as described above, thereby producing a double-sided signboard. This double-sided signboard was bright and had good uniformity of luminance distribution.

(Example 3) Except for using a prism sheet in which the first surface and the second surface of the prism row form an angle of 26 ° and 37 ° with the normal direction of the prism sheet, respectively. A double-sided surface light source element was obtained in the same manner as in Example 2. The peak of the distribution of light emitted from the double-sided light source element was in a direction inclined by about 14 ° with respect to the normal direction.

A transparent acrylic resin plate on which a photograph was printed was placed as a transmission type display element on the prism sheet of the double-sided light source element obtained as described above, thereby producing a double-sided signboard. This double-sided signboard was bright and had good uniformity of luminance distribution.

[0055]

As described above, according to the double-sided light source device of the present invention, the fine structure having an average inclination angle of 0.5 to 25 ° is provided on at least one of the light exit surface and the back surface of the light guide. Is formed, so that it has high luminance and is excellent in uniformity of luminance distribution in the light emitting surface. Further, the double-sided marking device of the present invention using such a double-sided surface light source element can be easily reduced in thickness.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a first embodiment of a double-sided light source element according to the present invention.

FIG. 2 is a diagram showing a traveling state of light in a light guide of the double-sided light source element according to the present invention.

FIG. 3 is a partial sectional view showing a first embodiment of a double-sided light source element according to the present invention.

FIG. 4 is a partial cross-sectional view showing a modified example of the first embodiment of the double-sided light source element according to the present invention.

FIG. 5 is a sectional view showing a modified example of the shape of the light guide of the double-sided light source element according to the present invention.

FIG. 6 is a cross-sectional view showing a modification of the shape of the light guide of the double-sided light source element according to the present invention.

FIG. 7 is a partial sectional view showing a prism sheet of the first embodiment of the double-sided light source element according to the present invention.

FIG. 8 is a partial cross-sectional view for explaining a double-sided light source element according to a second embodiment of the present invention.

FIG. 9 is a partial cross-sectional view for explaining a third embodiment of the double-sided light source element according to the present invention.

FIG. 10 is a partial cross-sectional view illustrating a fourth embodiment of a double-sided light source element according to the present invention.

[Explanation of symbols]

 2, 2A, 2B, 2A, 2B Light source 4, 4A, 4B Light guide 6A, 6B Light bending sheet 8, 8A, 8B Reflective film 10, 10A, 10B Reflective sheet 12A First element 12B Second element 14A, 14B Transmissive marking element 22, 22 'Light incident surface 24, 24A, 24B Light emitting surface 26 Back surface

Claims (11)

[Claims] A first element for emitting light to a first surface side;
A second for emitting light to a second surface side opposite to the first surface side;
The first element and the second element each include a light source, at least one side end face facing the light source is a light incident surface, and one surface substantially orthogonal to the light incident surface is a light incident surface. A light guide serving as an emission surface, and a light bending sheet disposed on the light emission surface side of the light guide, wherein at least one of a light emission surface of the light guide and a back surface thereof has an average inclination. A double-sided surface having a microstructure having an angle of 0.5 to 25 °, wherein the first element and the second element are arranged such that the back surfaces of the light guides face each other. Light source element. 2. The double-sided surface light source device according to claim 1, wherein the first element and the second element have a reflection surface disposed adjacent to and opposed to a back surface of the light guide. 3. The double-sided light source device according to claim 2, wherein a reflection surface of the first element and a reflection surface of the second element are formed on a common member. 4. The light source of the first element and the light source of the second element are shared.
A double-sided surface light source device according to any one of the above. 5. A light source and at least one light source facing the light source.
A light guide having two side end surfaces as light incident surfaces, and two surfaces substantially orthogonal to the light incident surface having light exit surfaces on a first surface side and a second surface side; and a first surface side of the light guide. And at least one of the light exit surfaces on the first surface side and the second surface side of the light guide has an average inclination angle. A double-sided light source element having a microstructure of 0.5 to 25 °. 6. The double-sided light source device according to claim 1, wherein the fine structure is formed of a rough surface. 7. The double-sided light source device according to claim 1, wherein the fine structure includes a plurality of lens arrays extending in a direction parallel to the light incident surface. . 8. An average inclination angle of the fine structure is 0.5 to 0.5.
The angle is within the range of 7.5 °.
8. The double-sided light source element according to any one of 7. 9. The double-sided surface according to claim 1, wherein the optically variable angle sheet comprises a lens sheet having a large number of lens rows formed on at least one surface thereof in parallel with each other. Light source element. 10. The double-sided light source device according to claim 9, wherein the lens sheet is a prism sheet having a plurality of prism rows formed on at least one surface thereof in parallel with each other. 11. A double-sided light source device according to claim 1, wherein a first and a second transmissive marking elements are respectively arranged on the first surface side and the second surface side. Double-sided marking device.