JP3327656B2 - Method for manufacturing wedge-shaped light guide plate, wedge-shaped light guide plate, and planar illuminator using the light guide plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wedge-shaped light guide plate of an edge light type and an improvement of a surface illuminator using the light guide plate.

[0002]

2. Description of the Related Art A light guide plate of this type is widely used as a surface light source of a surface-type illuminating body for performing uniform illumination by diffusing light from a cold-cathode tube disposed at an edge into a wide area and outputting the same. In recent years, it has been widely used as a backlight of a liquid crystal display device.

Conventional technology and its problems (i) Flat-type light guide plate Many conventional edge-light-type light guide plates use a flat plate made of an acrylic resin and have uniform white dots printed on a reflective printing surface. (Japanese Utility Model Laid-Open No. 54-146183),
Alternatively, white dots with coarse and dense prints are printed on a printing surface for reflection (JP-A-54-35776, JP-A-57-57776).
No. 128383, U.S. Pat. No. 4,985,809)
Many inventions and inventions have been made. However, in all of these, since the light guide plate (1 ') is a flat plate, light having no prismatic property and entering parallel to the upper and lower surfaces of the flat light guide plate (1') is flat as shown in FIG. There is a problem in that the light does not reciprocate without hitting the upper and lower surfaces of the light guide plate (1 '), and as a result, there is a high probability that the heat is wasted. FIG. 16 shows the tendency.

FIG. 16 shows the result of examining the difference in light output depending on the shape of the light guide plate. In FIG. 16, curve A is a luminance distribution curve of the light emitting surface (S2 ') of the conventional flat light guide plate (1'), and FIG. 14 shows a schematic cross section of the flat light guide plate (1 '). A curve B is a luminance distribution curve of the light emitting surface (S2) of the wedge-shaped light guide plate (1) used in the present invention, and FIG. 15 shows the wedge-shaped light guide plate (1). Both light guide plates (1) (1 ')
Are for the purpose of purely comparing the difference in the degree of light emission depending on the shape of the light guide plate without printing.

FIG. 16 shows the difference in light output between the flat light guide plate (1 ') and the wedge-shaped light guide plate (1) without printing white dots as described above. As is clear from the curves A and B, FIG. It can be seen that the flat light plate (1 ') is less likely to emit light than the wedge-shaped light guide plate (1).

As described above, since the flat-type light guide plate (1 ') has a structure in which light is hardly emitted, the backlight of a liquid crystal display device (especially, such as a color liquid crystal display device) which requires high luminance is required. Not suitable for Further, the flat light guide plate (1 ') is about 35% to 40% heavier than the wedge-shaped light guide plate (1) and has a fundamental problem as a backlight of a liquid crystal display device which is required to be strictly reduced in weight. In short, the flat light guide plate (1 ') is a wedge-shaped light guide plate.
It can be understood from FIG. 16 that there is a fundamental problem that the light is hardly emitted and that it is heavy in comparison with (1).

Next, the effect of the wedge-shaped light guide plate (1) on the luminance of the reflection processing surface (S3) will be described. 《Experimental example》
The wedge-shaped light guide plate (1) has a wedge-shaped light guide plate (1), in which white paint is applied to the entire surface to be processed for reflection (S3) (FIG. 17), and the wedge-shaped light guide plate (1) described later has an entire surface of the processed surface for reflection (S3). Groove evenly
The case where (6a) is provided will be described. U.S. Pat.No. 4,27
No. 7,817 describes a wedge-shaped light guide plate (1) of the former type. However, when the white paint is applied to the entire surface of the reflective surface, most of the light is emitted at the part close to the cold cathode tube, which is the light source (2), and the light emitting surface is orthogonal to the cold cathode tube (2). The luminance distribution on (S2) is quite non-uniform (as can be seen from the figure, it can be seen that the luminance gradually decreases as the distance from the light source (2) increases) and is not endurable for industrial use. FIG. 17 shows the luminance distribution tested by the inventor on a wedge-shaped light guide plate (1) having a screen width of 5.5 ″. FIG. 17 shows a cold cathode tube
This clearly shows that most of the light is emitted on the (2) side.

FIG. 18 is a luminance distribution graph when the wedge-shaped light guide plate (1) and the uniform concave groove (6a) are formed on the reflection processing surface (S3). JP-A-59-210411 discloses the latter wedge-shaped light guide plate (1), which is formed by providing a concave groove (6a) in place of the former print dot (6). However, this also emits light on the side close to the cold cathode tube (2) in the same concave groove (6a) as in the front white paint,
It turned out to be unsuitable for industrial use.

As described above, in the conventional light guide plate, there is almost no case in which the brightness of the light emitting surface is formed substantially uniformly over the whole surface. `` Qualitative description '' of only about `` applied to the surface (S3) '' can be seen, but there is no detailed and specific description of how coarse or dense it is. Was not done until.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the conventional light guide plate. It is an object of the present invention to make it possible to perform "quantitative" processing and to enable industrial processing of a processing surface for reflection.

[0011]

Means for Solving the Problems Claim 1 is directed to the "wide side
The light incident side (S1) where the light from the light source (2) enters
The narrow side (S4) opposite the writing light side (S1) and the front
A light-emitting surface (S2) intersecting both side surfaces (S1) and (S4), and the light-emitting surface
(S2) and a light reflection processing surface (S3) located on the opposite side
In the method for manufacturing a wedge-shaped light guide plate, the light reflection processing surface (S
3), white dots (6), grooves (6a), ridges (6b), recesses (6c)
Or any of the protrusions (6d) are distributed according to the following formula.
A method for manufacturing a wedge-shaped light guide plate, characterized in that the light guide plate is formed as follows. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
Distance P (x) on the light exit surface of the light plate ; printing rate distribution or processing degree distribution α of the wedge-shaped light guide plate; light emission rate L ′; shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; N, K to the end ; positive constant ”. The wedge-shaped light guide plate (1) according to claim 2 is “a wide side surface,
Light incident side surface (S1) where light from the light source (2) enters, a narrow side surface (S4) located on the opposite side of the light incident side surface (S1), and the both side surfaces (S1) (S4) In a wedge-shaped light guide plate (1) having an intersecting light emitting surface (S2) and a light reflecting processed surface (S3) located on the opposite side of the light emitting surface (S2), the light reflecting processed surface (S3) , White
(6) are printed so as to be distributed according to the following formula.
A wedge-shaped light guide plate, P (x) = <(1 / K) · 1 / [{(x 1 / α) -x} · (L'-x)]> (1 / n) where 0 ≦ x ≦ x ₁ x; the light source A wedge-shaped guide extending vertically from the light source end to the back
The distance P (x) on the light exit surface of the light plate ; the printing rate distribution α of the wedge-shaped light guide plate; the light emission rate L ′; the shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; Distance n, K; positive constant ”.

According to the basic formula P (x), the light-reflection processing surface (S3)
Wedge-shaped light guide with one or a small number of prototypes
Maintains the light output rate over the entire surface of the plate (1) with high accuracy and constant
To reduce the processing time of the light reflection processing surface (S3)
Can do things. Further , the light output rate on the light incident side (S1) side of the light output surface (S2) is suppressed low, and the light output rate gradually increases toward the narrow side surface (S4) side, and as a whole the light output surface (S2) The light emission rate is uniform, and uniform brightness is secured.

[0013] The wedge-shaped light guide plate (1) according to the third aspect of the present invention is characterized in that "a light-entering side surface (S1) on which light from a light source (2) is incident is a wide side surface.
And a narrow side surface (S4) located on the opposite side of the light incident side surface (S1).
And a light emitting surface (S2) intersecting the both side surfaces (S1) and (S4), and a wedge-shaped light guide plate (1) having a light reflecting processed surface (S3) located on the opposite side of the light emitting surface (S2). At the light reflection processing surface (S3) side
The grooves (6a) to ridges (6b) are distributed according to the following formula.
A wedge-shaped light guide plate characterized by being formed as follows. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
The distance P (x) on the light exit surface of the light plate ; the processing degree distribution α of the wedge-shaped light guide plate; the light emission rate L ′; the shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; Distance n, K; positive constant ”.

According to the basic formula P (x), the light reflecting surface (S3)
Wedge-shaped light guide with one or a small number of prototypes
Maintains the light output rate over the entire surface of the plate (1) with high accuracy and constant
To reduce the processing time of the light reflection processing surface (S3)
Can do things.

[0015] The wedge-shaped light guide plate (1) according to the fourth aspect is characterized in that "a light-entering side surface (S1) on which light from the light source (2) is incident is a wide side surface.
And a narrow side surface (S4) located on the opposite side of the light incident side surface (S1).
And a light emitting surface (S2) intersecting the both side surfaces (S1) and (S4), and a wedge-shaped light guide plate (1) having a light reflecting processed surface (S3) located on the opposite side of the light emitting surface (S2). At the light reflection processing surface (S3) side
The recesses (6c) to protrusions (6d) are distributed according to the following formula.
A wedge-shaped light guide plate characterized by being formed as follows. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
The distance P (x) on the light exit surface of the light plate ; the processing degree distribution α of the wedge-shaped light guide plate; the light emission rate L ′; the shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; Distance n, K; positive constant ”.

In this case as well, the basic expression P (x) is
Therefore, when processing is performed on the light reflection processing surface (S3), once to
With almost no trial production, the light output from almost the entire surface of the wedge-shaped light guide plate (1) was
The luminous efficiency can be made constant with high accuracy, and the light reflection processing surface
The processing time of (S3) can be reduced.

[0017]

[0018]

A fifth aspect of the present invention is directed to any one of the second to fourth aspects.
In wedge-shaped light guide plate, wherein the light source (2) to print ratio in the near side printing or processing end region of the working ratio GaOsamu formal "P
(x) + P '(x) " .
You. The correction formula is as follows. “P (x) + P ′ (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} ·
(L′−x)]> ^{(1 / n)} + (A ₁ −B ₁ x) where 0 ≦ x ≦ (A ₁ / B ₁ ) (A ₁ / B ₁ ); distance constant A experimentally obtained ₁ ; Modified printing ratio or degree of processing determined experimentally x: Distance on the light exit surface of the wedge-shaped light guide plate going from the light source end to the back in a direction perpendicular to the light source P (x); Print ratio distribution or wedge-shaped light guide plate Workability distribution P '(x); Critical angle disturbance on the light incident side surface of the wedge-shaped light guide plate
Correction term α; Light output rate L '; Shape factor determined by the shape of the wedge-shaped light guide plate x ₁ ; Distance from the light source end to the innermost end of the printing or processing area n, K ; Positive constant "

[0020] Before KiOsamu formal Doing processed light reflecting processing surface (S3) according to the "P (x) + P '( x) ", the light source (2) side printing or processing end region Any other near It is possible to achieve almost the same brightness as the part.

A sixth aspect of the present invention is directed to any one of the second to fourth aspects.
In wedge-shaped light guide plate according, characterized in that formed in accordance with the light source printing of the printing or processing end region from the (2) side farther to the working ratio GaOsamu formal "P (x) + P '' (x) " When
I do. The correction formula is as follows. “P (x) + P ″ (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} ·
(L′−x)]> ^{(1 / n)} + (a ₁ −b ₁ x) where (a ₁ / b ₁ ) ≦ x ≦ x ₁ (a ₁ / b ₁ ); distance constant experimentally obtained a ₁ : Modified printing ratio or degree of processing determined experimentally x: Distance on the light-emitting surface of the wedge-shaped light guide plate extending from the light source end in the direction perpendicular to the light source P (x); Print ratio distribution of the wedge-shaped light guide plate Or processing degree distribution P ″ (x); reflection failure on the innermost end face of the wedge-shaped light guide plate
Correction factor α; light output rate L ′; shape factor determined by the shape of the wedge-shaped light guide plate x ₁ ; distance from the light source end to the innermost end of the printing or processing area n, K ; positive constant ”

[0022] Before KiOsamu formal Doing processed into "P (x) + P" ( x) "light reflecting processing surface according to (S3), the light source (2) to another in the far side printing or processing end region of the It is possible to achieve almost the same brightness as the part.

A seventh aspect of the present invention relates to a surface illumination body.
`` The light-entering side where the light from the light source (2) enters
(S1) and a narrow side surface located on the opposite side of the light incident side surface (S1).
(S4), and a light emitting surface (S2) intersecting the both side surfaces (S1) and (S4),
Light-reflection processing surface (S3) located on the opposite side of the light exit surface (S2)
Having a white dot on the light reflection processing surface (S3).
(6), grooves (6a), ridges (6b), the recesses (6c) to the projection (6d) Noi
A wedge-shaped light guide plate (1) formed so that the deviation is distributed according to the following equation ; a light source (2) arranged along the light incident side surface (S1) of the wedge-shaped light guide plate (1) ; Light exit surface of light plate (1)
(S3) a light-scattering plate (3) disposed on the wedge-shaped light guide
Light reflecting along the working surface (S3) comprises arranged reflective sheet (4), a surface-type illumination of the plate (1). P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
Distance P (x) on the light exit surface of the light plate ; printing rate distribution or processing degree distribution α of the wedge-shaped light guide plate; light emission rate L ′; shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; N, K to the end ; positive constant ”.

[0024] Thus, the light incident side surface (S1) side of Idemitsu rate of the light exit surface (S2) is even our low, which narrow side (S4) to the light exit rate toward the side is increased gradually, Idemitsu Light emission is uniform over the entire surface (S2) and uniform brightness is secured, and a very bright and easy-to-view surface illuminator (A) can be obtained.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. First, various embodiments of the wedge-shaped light guide plate (1) used in the present invention and a planar illuminator (A) using the wedge-shaped light guide plate (1) will be described. A first embodiment of the wedge-shaped light guide plate (1) is shown in FIG.
As shown in FIGS. 2 and 3, this is an example in which white printed dots (6) are provided on the reflection processing surface (S3), and the second embodiment has a shallow cross section parallel to the light incident end surface (S1) as shown in FIG. FIG. 4 shows an example in which a large number of triangular concave stripes (6a) are formed in a hairline shape.
3 shows an example in which a low ridge (6b) protrudes in a hairline shape in parallel to the light incident end face (S3) as opposed to FIG. 3, and the fourth embodiment has a small conical shape as shown in FIG. The fifth embodiment is an example in which a large number of recesses (6c) are recessed. In the fifth embodiment, as shown in FIG.
This is an example in which many (6d) are protruded. Of course, processing surface for reflection (S3)
However, the present invention is not limited to these, and it is also possible to form the concave streak (6a) or the protrusion (6b) so as to be inclined with respect to the light incident end surface (S3), or to cross them. It is. The present invention relates to the quantification of the degree of processing applied to the processing surface for reflection (S3).

As shown in FIG. 1, the wedge-shaped light guide plate (1) has a light incident end surface (S1) formed to be wide, and a reflection end surface (S4) opposite to the light incident end surface (S1) has a narrow width. Formed, both end faces (S1)
The processing surface for reflection (S3) is formed so as to be inclined with respect to the light emitting surface (S2) between (S4), and the cross section is formed as if it were wedge-shaped. In the present embodiment, the light exit surface (S2) is perpendicular to the light incident end surface (S1), and the processing surface for reflection is used.
Although (S3) is shown inclined with respect to the light incident end surface (S1), conversely, the light emitting surface (S2) is inclined with respect to the light incident end surface (S1), and it is used for reflection. It goes without saying that a processing surface (S3) having a right angle to the light incident end surface (S1) may be used. In general, an acrylic plate having excellent light transmission properties is used.

A cold-cathode tube (2) serving as a light source (21) is provided along the light-incident end surface (S1) of the wedge-shaped light guide plate (1). This cold cathode tube
Behind (2) is provided a reflector (7) formed in a concave surface. Further, a reflection sheet (4) is provided below the reflection processing surface (S3) of the wedge-shaped light guide plate (1), and the light exit surface (S
A scattering sheet (3) is set on 2).

A part of the light emitted from the light source (2) is incident on the light incident end face (S
The light directly enters 1), and the remainder is reflected by the reflector (7) and enters the light. The incoming light travels straight through the wedge-shaped light guide plate (1), and the majority of the light enters the processing surface for reflection (S3) or the reflection sheet.
The light is reflected by (4), its path is changed, and countless reflections are repeated, and most of the light is emitted from the light emitting surface (S2). Light emitting surface
(S2) or a part of the light incident substantially parallel to the processing surface for reflection (S3) is reflected by the reflection end surface (S
The light is reflected by the end face reflection sheet (5) disposed in 4) and is reflected to the light incident end face (S1) side, but is re-reflected by the reflector (7) to change the course, and finally emits light. It has become. Next, with simple white painting or qualitative white dot printing, it is not possible to obtain a light-emitting surface that exhibits a substantially uniform luminance that is industrially satisfactory as shown in the conventional example,
The processing performed on the reflection processing surface (S3) to obtain a substantially uniform luminance distribution on the light exit surface (S2) will be described with reference to FIGS. The unit of luminance is C
d / m ² , and the unit of distance is cm.

The cross section of the wedge-shaped light guide plate (1), which is cut along a plane perpendicular to the cold-cathode tube (2) disposed on the light incident end surface (S1) of the wedge-shaped light guide plate (1), ), The brightness Z (x) of the minute light exit surface dx at a position x is << I >> proportional to the amount of residual light at the position x. << II >> It is proportional to the thickness y (x) of the wedge-shaped light guide plate (1) at the position x. << III >> It is proportional to the light emission rate E (x) at the position x. Assume that Assuming that the thickness of the light incident side surface (S1) facing the cold cathode tube (2) is (B) and the light incident luminance of the light incident side surface (S1) is (Zo), the light incident side is 1 cm in depth. Light quantity (Qo) = B × 1 × Zo = B · Zo. The output light amount on the light output surface (S2) between _{0 and} ^x is ∫0xZ (x) dx. Therefore, x = x (i.e., position x) the remaining amount of the, the ^{_{B · Zo-∫ 0 x Z}} (x) dx ....

Based on the assumptions << I >> to << III >>, the following expression is obtained which represents the luminance distribution on the light exit surface (S2) of the wedge-shaped light guide plate (1). Z (x) = K ′ ｛B · Zo−∫ ₀ ^x Z (x) dx｝ y (x) E (x) where K ′ is a proportionality constant and, as described above, y (x) Is the thickness of the wedge-shaped light guide plate (1) at the position (x), and E (x) is the light emission rate at the position (x). y (x) is determined by the shape of the wedge-shaped light guide plate (1), and if the shape is defined as shown in FIG. y (x) = {L / (B−b)} · {BL / (B−b) −x}

In the case of white dot printing (6), the light emission rate E (x) is proportional to the nth power of the printing rate P (x) [= the area of the printed portion per unit area]. It is represented by the following equation. E (x) = kP (x) ⁿ ...

The concave line (6a) or the ridge line (6
Also in the case of b), the light output rate E (x) can be expressed as follows, assuming that it is proportional to the n-th power of the processing degree P (x). E (x) = kP (x) ⁿ ...- 1

Further, the small conical recess (6c) and the small conical protrusion (6c)
The same applies to the case of d), and the light emission rate E (x) can be expressed as follows, assuming that it is proportional to the n-th power of the processing degree P (x). E (x) = kP (x) ⁿ ... -2 Note that the above-mentioned −1 and −2 use the same reference numerals.

Or, when -1 or -2 is substituted for, the general formula is expressed as follows. Z (x) = K ｛B ・ Zo-∫ ₀ ^x Z (x) dx｝ · P (x) ⁿ・ (L′-x) where K = K ′ ・ k ｛｛L / (B− b)｝ and L ′ = BL / (B−b) (10) L 'in (10) is a shape factor determined by the shape of the wedge-shaped light guide plate (1). K is a constant represented by

Further, assuming that uniform luminance (Zc) is obtained by an appropriate distribution of the printing ratio P (x) or the degree of processing P (x), the following is obtained. Zc = K (B · Zo−Zc · x) · P (x) ⁿ · (L′−x) (11)

When P (x) ⁿ is put out on the left side and rearranged, the equation is expressed as follows. P (x) ⁿ = (1 / K) · 1 / <{(Zo · B / Zc) −x} (L′−x)> (12) That is, (12) is a uniform luminance distribution (Zc). This is a general expression for obtaining P (x) necessary to obtain the following.

(12) is the printing rate distribution on the light emitting surface (S2) in the direction perpendicular to the cold cathode tube (2) if n, K, (Zo · B / Zc) and L ′ are determined, or Ridge (6a), ridge (6b), small conical recess (6
c) and the working degree distribution of the small conical protrusions (6d) can be calculated. Among them, L ′ is a shape factor, which can be calculated by (10). Next, assuming that the incoming light quantity (Zo · B) is equal to the outgoing light quantity (Zc · x ₁ ), (Zo · B) = (Zc · x ₁ ) (13) where (x ₁ ) Is the cold cathode tube (2) on the light emitting surface (S2)
Represents the position furthest from. In practice, the light that has entered is absorbed or leaked by the passing equipment, so the equation is rewritten as follows. Zo ・ B> Zc ・ x ₁ … (14)

This can be rewritten as follows. α · Zo · B = Zc · x ₁ where α is as follows when rearranged by a constant smaller than 1. α = (Zc · x ₁ ) / (Zo · B) (15) where 0 <α <1. Furthermore, this can be rewritten as follows. (Zo · B) / Zc = x ₁ / α (16)

By substituting (16) for (12) and raising both sides to (1 / n), the following is obtained. P (x) = <(1 / K) · 1 / [{(x 1 / α) -x} · (L '-x)]> (1 / n) ... (17)

As can be seen from (15), (α) is the light output rate of the entire light guide plate, and theoretically (B) is large and (L) is small. That is, a value closer to the prism has a larger value. (α) is usually in the range of 0.70 to 0.98.
(n) is an index that mainly depends on the paint performance, and usually (n) =
It is between 1 and 4. Here, by appropriately determining (n), (α), and (1 / K), the printing rate distribution or the ridges can be calculated from (17).
Workability distribution P (x) such as (6a) and concave streak (6b) is obtained. In a wedge-shaped light guide plate having a normal shape, x ₁ <x ₁ / α <L ′ (18), and the entire graph of (17) is generally drawn as shown in FIG. 11. range is in the range of _{0~ (x 1 / α),} (x 1 / α) < x ranges, no any meaning here.

[0041] FIG 10 is a special hyperbolic, not expresses the print ratio distribution curve P between 0 to x ₁ in FIG. 10 in the claim 1 to 4 (x), of our invention in the hyperbola Most are represented.

The hair line is attached in the groove as described above.
(6a), or a ridge (6b) as shown in FIG. Of course, the light emission effect is quite different, so equation (17)
(Α), (n), K and other constants need to be changed as appropriate. In this embodiment, the cross-sectional shape is a triangle, but a quadrangle, a semicircle, or any other appropriate shape is used. Therefore, what is illustrated here is merely an example of the present invention, and the cross-sectional shape is not limited thereby.

Here, the groove (6a) constituting the hairline
The meaning of the degree of processing in the ridge (6b) will be described. [I] Degree of processing of the concave groove (6a) constituting the hairline (1) When the depth of the concave groove (6a) and the cut length are both (a) (FIG. 5). In the case where "the length of the cross section of the concave groove (6a) at the unit cross section length (1 cm) (the length of ABC = AB + BC) is defined as the degree of processing " , the following is obtained. AB = d = {(a / 2) ² + a ² } = (a√5) / 2 ABC length = AB + BC = 2d = a√5 Therefore, the length of the hairline cross section is the depth (a) or the cut length Sa
It is proportional to (a). (2) When the cross-sectional shape of the concave groove (6a) is an equilateral triangle, the length (2d) of the line cross section becomes (2a), which is proportional to the cut length (a). In this case, the depth is {a ({3) / 2}}. (3) From the above, “From the light incident side to the light reflection processing surface, narrow side
Toward the surface, in the cut surface in the direction orthogonal to the light incident side surface
Construct the contour of the groove or ridge processed on the light reflection processing surface side.
The line length to be formed is a wedge-shaped light guide plate that is perpendicular to the cold-cathode tube (2).
The length (d) of one side of the contour line of the concave groove (6a) to the ridge (6b) constituting the hairline per unit length (1 cm) of the cross section obtained by cutting (1) on the reflection processing surface (S3) side per unit length (1 cm) ) To the total length (2d).

Next, the working degree P (x) and the groove (6a) to the ridge (6)
The relationship between the length (d) and the total length (2d) of one side of the contour line in b) will be described. (i) As shown in FIG. 5, when both the depth of the groove (6a) and the length of the cut are (a), one hairline ｛= groove (6
a) The length (2d) caused by｝ is (a√5)
cm. When (n) concave grooves (6a) are formed in a unit length (1 cm), the processing length (nd) of the entire concave groove (6a) per unit length is (nd) = (na ・ 5 cm). become. Therefore,
Degree of processing P (x) = (na ・ 5cm) / (1cm) = (na ・)
5 <dimensions>), and the working degree P (x) is proportional to the length (d). (ii) The same applies to the case where the cross section is an equilateral triangle, and the length (d) = 2 generated by one contour of the concave groove (6a) constituting the hair line
acm. Assuming that there are (n) hair lines in a unit length of 1 cm of the reflection processing surface (S3), the processing degree P (x) is (2n
a), and the working degree P (x) is proportional to the ratio (dimensionless number) of the contour length (d) of the recess (6a) per unit length as described above. Such a relationship also applies to the ridge (6b). In the above description, the ratio of the contour length (d) of the recess (6a) was calculated by the number per unit length, but as the depth was increased, the contour of the recess (6a) at the unit length was increased. The same is true even if the ratio (dimensionless number) of the length (d) is increased. In other words, the increasing rate of (d) per unit length may be increased by increasing the number or by increasing the depth.

The degree of processing P (x) of the concave part (6c) or the convex part (6d) constituting the mark according to any one of claims 1 to 4 is a unit area on the processing surface for reflection (S3). Protruding part (6d) or recess
A distribution curve (referred to as processing degree distribution) of the engraved surface volume of (6c) is obtained. There are various shapes of the stamp. There are a cone, an n-pyramid, a cylinder, and the like. The shape described above is merely an example as described above, and the shape is not limited thereby.

[II] Degree of processing of the recess (6c) forming the stamp (see FIG. 6) (i) When the stamp shape (6c) is a cone having a depth (a) and a diameter (a) of the bottom circle, the cone When spreading the (6c), when there are m recesses (6c) in a fan area ^{Acm 2 = (√ 5/4) πa} 2 cm 2 per unit area (1 cm ²⁾ per cone, the working ratio P ( x) is as follows. P (x) = (√ 5/4 ) πa 2 · m ( dimensionless number) (ii) stamped shape (6c) of the bottom circle diameter (a), the length of the edge (a)
In the case of a sector of a cone Acm ² = (１) πa ² cm ² Assuming that there are m recesses (6c) per unit area (1 cm ² ), the processing degree P (x) is as follows: Become like P (x) = (1/2) πa ² · m (dimensionless number) (iii) From the above, the processing degree of the mark (6c) is determined by the processing reflection surface (S
The percentage of the newly generated surface area (dimensionless) is obtained by the marking per unit area in 3). In this case, as described above, the ratio of the surface area newly generated by the marking per unit area may be increased by increasing the number of the markings (6c) or increasing the depth of the markings (6c). The same applies to the case of the protrusion (6d).

Next, the critical angle obstacle on the light incident side surface (S1) will be described. As shown in FIG. 8, in the case of the wedge-shaped acrylic light guide plate (1), the processing surface for reflection (S
In the range (B ') on the light incident side surface (S1) side from the downward inclined line going to (3) (at θ = 47.9 °), light does not enter because of the critical angle of acrylic. Therefore, the area (B ′) of the area (area filled with the intersection line) is the light incident end (S1) of the wedge-shaped light guide plate (1) facing the cold cathode tube (2) when the equation (17) is induced. Does not follow the light-guiding behavior described above, and even when printed in accordance with the printing rate distribution calculated by the equation (17), it is always slightly darker than the average value, which hinders realization of uniform brightness on the light exit surface (S2). Therefore, it is necessary to add a correction term P ′ (x) as shown in claim 5 to the right side of equation (17). P ′ (x) = A ₁ −B ₁ · x where 0 <x <(A ₁ / B ₁ ) FIG.
reference. There is a relationship of nB ′ = A ₁ / B ₁ n≫1 between (B ′) in FIG. 8 and A ₁ and B ₁ , but n is larger than expected. This means that
This is because, as the incident angle increases, the reflectance on the acrylic surface increases, and the light incidence is small in a range considerably larger than (B ′). That is, it is like a critical angle obstacle of the light guide plate material. A1 is 0.02 to 0.2 when P '(x) is the printing rate.
It is about 06.

Next, a description will be given of a reflection failure on the innermost end face of the wedge-shaped light guide plate (1). In the wedge-shaped light guide plate (1), a reflection tape (5) is usually attached to the innermost end surface (S4). For this reason, the reflection tape (5) causes a reflection phenomenon of light at the innermost end face (S4), and due to the reflected light, the innermost end face (S4).
In (S4), a region that does not follow the assumption at the time of deriving Expression (17) occurs. That is, this is a reflection failure, and the light emitting surface (S2)
In order to achieve the uniform brightness of the above, it is necessary to correct the processing formula. That is, as shown in claim 6, a correction term of P ″ (x) = a ₁ −b ₁ · x where (a ₁ / b ₁ ) <x <x ₁ is added to the right side of equation (17). There is a need to. Assuming that mb = x ₁ − (a ₁ / b ₁ ) with respect to the thickness (b) of the innermost end surface (S 4), normally (m) is about 10 to 20. or,
(a ₁ ) is in the range of 0.02 to 0.06 and (b) is large.
Both (a ₁ ) and (m) need to be increased.

A wedge-shaped light guide plate is obtained by adding the printing rate distribution equation obtained by adding the guarantee equation (17) for high brightness on the light exit surface (S3) and the correction term P ′ (x) and / or P ″ (x). The average luminance obtained by printing in (1) is the highest if the uniformity is sufficiently high. That is, it is assumed that the uniformity is 100% in the printing rate distribution P (x) * in this example, and the average luminance at that time is Zc *. See FIG. If the print rate in this system P1 (x) * deliberately inlet luminance increases Increasing like, the inner part is lower than the average for the amount of light decreases _{(Z 1 (x) *)} . Conversely, keep the printing rate on the entrance side low,
_{With 2} (x) *, the brightness on the entrance side is low and the depth on the back side is high (Z ₂ (x) *). That is, the uniformity deteriorates in both cases, so that the average luminance at which 100% uniformity is obtained by repeating the trial production becomes the highest luminance in the equipment system used. That is, if a highly uniform wedge-shaped light guide plate (1) is obtained by using claims 1 to 6 invented by the inventors, it can be said that it is close to the maximum luminance in terms of luminance.
This discussion can of course be applied to the wedge-shaped light guide plate (1) which has been subjected to the hairline processing or the engraving processing.

EXPERIMENTAL EXAMPLE 1 A 3 "wide, 4 mm thick light incident side surface (S1) on the cold cathode tube (2) side,
Assuming a 90% light output rate with a 1.5 mm thick wedge-shaped light guide plate (1) on the opposite reflection side surface (S4), Equation 17 is as follows. (Unit: mm) P (x) = {54.5 / (51.1-x) · (63.4-x)} ^{(1 / n)} (19) Then, assuming (n), paint Is selected and the printing is performed, and BEF (trade name) and 100S
-2 (trade name), K-90 (trade name) as reflective sheet (4), Lipic tape (trade name) as light-shielding tape (5), and GR-38W (trade name) as reflector (7) When the surface illuminator (A) was assembled and the luminance distribution was measured, the average luminance was 3,930 Cd / m ² , the uniformity was [the light emitting surface of the wedge-shaped light guide plate (1) in the direction perpendicular to the cold cathode tubes (2)]. The minimum luminance and the maximum luminance are extracted from the luminance distribution curve on (S2), and (min luminance / maximum luminance) × 100 and displayed in%] is 8
4%. Then, (n) is slightly corrected, and as a correction for the critical angle obstacle, the following equation P ″ x = 0.03−0.003x where 0 <x <10 (unit mm) is inserted into the right side of (19). When the printing rate distribution was corrected and reproduced, the average luminance was 3,900 Cd / m ² and the uniformity was 88%.
The surface illuminator (A) with high brightness and high uniformity was obtained. In addition,
No correction was required for the reflection failure. Here, the materials used are as follows: (trade name) BEF: Sumitomo 3M Co., Ltd. (trade name) 100S-2: Kimoto Corporation (trade name) K-90: Kimoto Corporation (trade name) Name) GR-38W ... Kimoto Co., Ltd. (Product name) Rivic Tape ... Et Co., Ltd. Obtained from the above company.

EXPERIMENTAL EXAMPLE 2 9 "wide, 4 m thick light-incident side surface (S1) on the cold cathode tube (2) side
m, a 1.5-mm-thick wedge-shaped light guide plate (1) on the opposite side (S4), assuming a light output (100α) of 90%.
(17) was as follows. (Unit: cm) P (x) = {10.2 / (16.1-x) · (24-x)} ^{(1 / n)} (20) Then, assuming (n), the type of paint Printing is performed by selecting a density, and a surface-type illuminator using the same material as in the first embodiment.
(A) was assembled, and the luminance distribution was measured in the same manner as in Example 1. As a result, the average luminance was 2,200 Cd / m ² and the uniformity was 87%. The illuminator (A) was obtained.

Next, (α ₁ ) and (n) are slightly corrected, and then the following formula is used as a correction for the critical angle failure: P ′ (x) = 0.06-0.015x P "(x) = 0.09375-0.0075x However, 12.5 <x <14.5 was added to the right side of Equation 20, the printing rate was corrected, and the prototype was reproduced, and the same luminance distribution was measured. However, the average luminance is 2,180C
A light guide plate having a high luminance and a high degree of uniformity with d / m ² and a degree of uniformity of 89% and a slightly convex center was obtained.

EXPERIMENTAL EXAMPLE 3 A 3 "wide, 4 m thick light-incident side surface (S1) on the cold cathode tube (2) side.
m, the reflection side surface (S4) on the opposite side is 1.5 mm thick and the wedge-shaped light guide plate (1) has a light output rate of 80%, and the equation (17) is as follows. (Unit: mm) P (x) = {170 / (57.5-x) · (63.4-x)} ^{(1 / n)} (21) Then, assuming (n), the kerf is cut. Reflected surface (S3) as area distribution curve (cross section is triangular as in Fig. 3)
Was subjected to a hairline process, and a surface-type illuminating body (A) was assembled using the same members as in Example 1 to measure the luminance distribution. As a result, the average luminance was 4,280 Cd / m ² , and the uniformity was 82%. A hairline-type surface illuminator that can be used industrially as a backlight for liquid crystal was obtained in one trial production.

[0054]

As described above, according to the present invention, a light guide plate having high brightness and high uniformity can be easily obtained by printing or hairline or engraving on the reflection processing surface (S3) according to the basic formula (17). It has become inexpensive and extremely short-term. That is, as described above, in the patent literatures published so far, only the expression “qualitatively and densely” is used as a method of obtaining printing, hairline or engraving to obtain a light guide plate with high brightness and high uniformity. Did not disclose a specific quantitative method. According to claims 1 to 6 disclosed in the patent, it is possible to quantitatively calculate a printing rate distribution or a processing degree distribution for obtaining a light guide plate with high luminance and high uniformity. Accordingly, the surface-type illuminating body using the wedge-shaped light guide plate of the present invention has an advantage that it can be used as a high-quality liquid crystal backlight or a backlight for advertisement and other uses because of its light weight, high luminance and high uniformity. Further
In addition, in the present invention, the light output rate on the light incident side surface side of the light output surface is low.
And the light output gradually increases toward the narrow side.
Light emission is uniform over the entire light exit surface,
There is an advantage that one brightness is secured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of a wedge-shaped light guide plate used in the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a perspective view of a second embodiment of a wedge-shaped light guide plate used in the present invention.

FIG. 4 is a perspective view of a third embodiment of a wedge-shaped light guide plate used in the present invention.

FIG. 5 is a partially enlarged perspective view of a concave groove formed in the wedge-shaped light guide plate of the present invention.

FIG. 6 is an enlarged perspective view of a conical recess formed in the wedge-shaped light guide plate of the present invention.

FIG. 7 is an enlarged perspective view of a conical projection formed on the wedge-shaped light guide plate of the present invention.

FIG. 8 is a partially enlarged cross-sectional view for explaining a critical angle obstacle on a light incident side surface of the wedge-shaped light guide plate of the present invention.

FIG. 9 is an oblique projection view of a portion of the wedge-shaped light guide plate cut at a depth of 1 cm to explain a calculation formula of the present invention.

FIG. 10 is a sectional view of a wedge-shaped light guide plate for explaining a calculation formula of the present invention.

FIG. 11 is a graph showing a distribution of printing ratio or degree of processing for obtaining uniform brightness in the present invention.

FIG. 12 is a graph showing a relationship between high uniformity and high luminance of a light emitting surface according to the present invention.

FIG. 13 is a cross-sectional view showing a parallel light passing state in a conventional plate-shaped light guide plate.

FIG. 14 is a schematic structural sectional view of a conventional plate-shaped light guide plate.

FIG. 15 is a schematic sectional view of a wedge-shaped light guide plate according to the present invention.

FIG. 16 is a graph showing a difference in luminance distribution on the light exit surface between the flat light guide plate and the wedge light guide plate when the printing ratio is 0%.

FIG. 17 is a graph of the luminance distribution on the light exit surface of the wedge-shaped light guide plate when white paint is applied on the entire surface.

FIG. 18 is a graph of the luminance distribution on the light exit surface of the wedge-shaped light guide plate when uniform hairlines (concave grooves) are processed.

[Explanation of symbols]

 (1) Wedge-shaped light guide plate (2) Light source (6) White dot (S1) Light incident side (S2) Light exit surface (S3) Light-processed surface for reflection (S4) Narrow side

Continuation of front page (56) References JP-A-5-134251 (JP, A) JP-A-4-268506 (JP, A) JP-A-4-162002 (JP, A) JP-A-3-118593 (JP) JP-A-3-9304 (JP, A) JP-A-5-55103 (JP, U) JP-A-4-63402 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) G02B 6/00 331 F21V 8/00 601 G02F 1/13357

Claims (7)

(57) [Claims] A light incident surface on which light from a light source enters, a narrow side surface opposite to the light incident side surface, a light exit surface intersecting the both side surfaces, and the light exit surface. Made in wedge-shaped light guide plate having a light reflecting processing surface located opposite the surface
In the manufacturing method , a white dot, a concave groove, a ridge, a recess is formed on the light reflection processing surface.
Or any of the protrusions are distributed according to the following formula:
Forming a wedge-shaped light guide plate. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
Distance P (x) on the light exit surface of the light plate ; printing rate distribution or processing degree distribution α of the wedge-shaped light guide plate; light emission rate L ′; shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; Distance to edge n, K; positive constant 2. A light incident surface on which light from a light source is incident on a wide side surface, a narrow side surface opposite to the light incident side surface, a light exit surface intersecting the both side surfaces, and the light exit surface. A wedge-shaped light guide plate having a light-reflection processing surface located on the opposite side of the surface, wherein a white dot is formed on the light reflection processing surface according to the following formula:
A wedge-shaped light guide plate , which is printed so as to be distributed . P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
Distance P (x) on the light exit surface of the light plate ; print ratio distribution α of the wedge-shaped light guide plate; light output ratio L ′; shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; distance from the light source end to the innermost end of the print area n, K; positive constant 3. A light incident surface on which light from a light source enters, a narrow side surface opposite to the light incident side, a light exit surface intersecting the both side surfaces, and the light exit surface. A wedge-shaped light guide plate having a light-reflection processing surface located on the opposite side of the surface, wherein the light reflection processing surface has a concave groove or a ridge according to the following formula:
A wedge-shaped light guide plate , characterized in that it is formed so as to be distributed . P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
The distance P (x) on the light exit surface of the light plate ; the processing degree distribution α of the wedge-shaped light guide plate; the light emission rate L ′; the shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; the distance from the light source end to the innermost end of the processing area n, K; positive constant 4. A light receiving means for receiving light from a light source on a wide side surface.
A light side surface and a narrow side surface opposite to the light incident side surface
And a light exit surface intersecting the both side surfaces, and an opposite of the light exit surface
And a wedge-shaped light guide plate having a light reflection processing surface
In the light reflection processing surface, recesses or projections are formed according to the following equation.
Wedge-shaped, characterized in that they are distributed
Light guide plate. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
The distance P (x) on the light exit surface of the light plate ; the processing degree distribution α of the wedge-shaped light guide plate; the light emission rate L ′; the shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; the distance from the light source end to the innermost end of the processing area n, K; positive constant 5. The wedge-shaped conductor according to claim 2 , wherein a printing rate or a processing degree in a printing or processing end area on a side close to the light source is formed according to the following correction formula. Light board. P (x) + P ′ (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L ′
−x)]> ^{(1 / n)} + (A ₁ −B ₁ x) where 0 ≦ x ≦ (A ₁ / B ₁ ) (A ₁ / B ₁ ); distance constant experimentally obtained A ₁ ; experiment X: the distance on the light-emitting surface of the wedge-shaped light guide plate extending from the light source end in the direction perpendicular to the light source and P (x); the print rate distribution or the workability distribution of the wedge-shaped light guide plate P '(x): Critical angle disturbance on the light incident side of the wedge-shaped light guide plate
Correction term α; Light output rate L '; Shape factor determined by the shape of the wedge-shaped light guide plate x ₁ ; Distance from the light source end to the innermost end of the printing or processing area n, K ; Positive constant 6. The wedge-shaped conductor according to claim 2 , wherein a printing rate or a degree of processing in a printing or processing end area farther from the light source is formed according to the following correction formula. Light board. P (x) + P ″ (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} ·
^{(L'-x)]> (} 1 / n) + (a 1 -b 1 x) where _{(a 1 / b 1) ≦} x ≦ x 1 (a 1 / b 1); distance constant determined experimentally a ₁ : Modified printing ratio or degree of processing determined experimentally x: Distance on the light-emitting surface of the wedge-shaped light guide plate extending from the light source end in the direction perpendicular to the light source P (x); Print ratio distribution of the wedge-shaped light guide plate Or processing degree distribution P ″ (x); reflection failure on the innermost end face of the wedge-shaped light guide plate
Correction factor α; light output rate L '; shape factor determined by the shape of the wedge-shaped light guide plate x ₁ ; distance from the light source end to the innermost end of the printing or processing area n, K ; positive constant 7. A light incident surface on which light from a light source is incident on a wide side surface, a narrow side surface opposite to the light incident side surface, a light exit surface intersecting the both side surfaces, and the light exit surface. A light-reflection processing surface located on the opposite side of the surface, and the light-reflection processing surface does not include any of white dots, concave grooves, ridges, recesses or protrusions .
Re or the wedge-shaped light guide plate is formed so as to be distributed according to the following equation, a light source disposed along the light incident side surface of the wedge-shaped light guide plate, a light scattering plate disposed on the light exit surface of the wedge-shaped light guide plate , And
Along the optical reflective processing surface of the fine the wedge-shaped light guide plate comprises a arranged reflective sheet, a surface-type illumination body. P (x) = <(1 / K) · 1 / [{(x ₁ / α) −x} · (L′−x)]> ^{(1 / n)} where 0 ≦ x ≦ x ₁ x; A wedge-shaped guide extending vertically from the light source end to the back
Distance P (x) on the light exit surface of the light plate ; printing rate distribution or processing degree distribution α of the wedge-shaped light guide plate; light emission rate L ′; shape factor x ₁ determined by the shape of the wedge-shaped light guide plate ; Distance to edge n, K; positive constant