JP4256738B2 - Planar light source device and display device using the same - Google Patents

Description

  The present invention mainly relates to a planar light source device for supplying light to a display device such as a liquid crystal or a signboard and a display device using the device. More specifically, a planar light source device using a plurality of point light sources such as light emitting diodes (hereinafter simply referred to as LEDs) that emit monochromatic light of R (red), G (green), and B (blue), and The present invention relates to a display device using the device.

  A conventional planar light source device includes a light distribution means, an LED, a reflection means provided to face the light distribution means, a hollow region formed between the light distribution means and the reflection means, and a reflector. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 2002-258664 (page 4, left column, line 3 to page 5, left column, line 43, FIG. 1)

  In the conventional planar light source device, the luminance in the vicinity of the LED that is the point light source is higher than the luminance at a position far from the point light source, and uneven luminance occurs in the display, which deteriorates the display quality. There is.

  In view of the above circumstances, the present invention provides a planar light source device in which luminance unevenness does not occur in the portion directly above the light source in the light diffusion portion and other portions without using a light guide plate as an optical transmission path, It is an object of the present invention to provide a display device capable of obtaining excellent display characteristics by using the planar light source device.

The planar light source device of the present invention includes a housing having an opening, a first reflecting portion disposed on the bottom surface of the housing facing the opening, and a plurality of disposed on the bottom surface side. A planar light source device including a light source and a first diffusing portion disposed in the opening, wherein the light source is a point light source, and the deflection element including the point light source is the casing is disposed on the bottom side of which, and polarization angle element, Ri Na is configured to refract the outgoing light to the bottom side of the housing with respect to the incident light entering the polarization angle element,
The declination element is a surface substantially perpendicular to the bottom surface of the housing located on the point light source side, a bottom surface substantially parallel to the bottom surface of the housing, and a top line of the substantially parallel bottom surface At least a first inclined surface having a predetermined inclination angle on a substantially vertical surface side that is the incident surface, and the deflection element extends in a longitudinal direction of the casing, The cross section whose thickness increases from the opening side to the bottom side of the housing is a trapezoidal square column, and the declination is along the longitudinal direction of the bottom surface of the housing so as to cover the point light source group. A diffusion portion is provided in which the surface of the upper surface of the element is processed into an uneven surface .
The planar light source device of the present invention includes a housing having an opening, a first reflecting portion disposed on the bottom surface of the housing facing the opening, and a plurality of disposed on the bottom surface side. A planar light source device including a light source and a first diffusing portion disposed in the opening, wherein the light source is a point light source, and the deflection element including the point light source is the casing And the deflection element is configured to refract the emitted light toward the bottom side of the casing with respect to the incident light incident on the deflection element,
The declination element is substantially perpendicular to the bottom surface of the housing located on the point light source side, a bottom surface substantially parallel to the bottom surface of the housing, and the bottom surface of the housing A plurality of substantially parallel opposing surfaces, and a plurality of first inclined surfaces having a predetermined inclination angle from the respective top faces of the substantially parallel bottom surfaces and the plurality of opposing surfaces to the substantially vertical surface side that is the incident surface. And the deflection element extends in the longitudinal direction of the casing, and the deflection element extends along the longitudinal direction of the bottom surface of the casing so as to cover the top of the point light source group. It is characterized in that a diffusion portion is provided in which the upper surface is processed into an uneven surface.

  The display device of the present invention includes the planar light source device, and a display unit that is disposed above the planar light source device and performs display using light emitted from the planar light source device. It is said.

  As described above, according to the present invention, a large amount of light emitted from the deflection element can be emitted to the bottom surface side of the housing, so that the luminance in the vicinity of the point light source has a point light source. Therefore, the luminance of the display surface is not increased compared to the luminance at a position far away from the display, and luminance unevenness on the display surface can be suppressed. In addition, it suppresses the occurrence of uneven brightness, which can occur in the case of a conventional direct-type planar light source device, in which the luminance of the portion where the point light source exists on the surface of the diffusion portion is higher than that of the surrounding portion. Can do.

  Hereinafter, a planar light source device of the present invention and a display device using the device will be described with reference to the accompanying drawings.

Embodiment 1
1 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 1 of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. 4 is an LED array diagram showing an example of an LED array, FIG. 5 is an enlarged view of a main part for explaining an optical path of light passing through a declination element, and FIG. 6 is an LED related to Embodiment 1 of the present invention. It is a light distribution distribution diagram which shows the light distribution of emitted light.

  As shown in FIGS. 1 to 4, the planar light source device according to the first embodiment of the present invention includes a housing 1, a first reflection unit 2, a first diffusion unit 3, a plurality of point light sources 4, It consists of a point light source substrate 5 and a deflection element 6.

  The housing 1 is composed of a bottom surface portion and four side surface portions, and has an opening 1b facing the bottom surface 1a of the bottom surface portion. The housing 1 prevents light from leaking to the outside as much as possible, and the bottom surface 1a and the side surface 1c on the inside of the housing 1 so that the light is reflected on the inside and proceeds toward the opening 1b. The first reflecting portion 2 is provided at least on the bottom surface 1a.

  The reflection part 2 is not particularly limited in the present invention as long as it reflects light with regular reflection, diffuse reflection, or a combination thereof. For example, a white paint is applied to the inside of the housing 1. Or a metal plate such as aluminum or silver, or a metal plate such as aluminum or silver deposited by applying a reflective coating on the surface of a resin sheet or the like. It can be set as the vapor deposition board formed. In particular, by forming a coating layer in which a white paint or the like is applied to the inside of the housing 1, internal reflection can be improved without increasing the weight, and light loss can be reduced. In addition, it is preferable that the reflectance of the inner surface of the housing 1 is 90% or more in order to suppress reflection loss on the reflecting surface.

  The first diffusion part 3 is arranged so as to cover the entire opening 1b of the housing 1. The first diffusion portion 3 is made of a resin plate such as acrylic (PMMA), polyethylene terephthalate (PET), or polycarbonate (PC), or a plate having a function of transmitting light, such as a glass substrate. Also, a planar light source device having a wide directivity can be obtained by adding a reflecting material to the first diffusing section 3 or by roughening the surface to have a function of diffusing incident light. Can do.

  As the point light source 4, an LED, a laser diode (LD), or the like can be used. This point light source 4 uses an LED, the first point light source 4a emitting red (R) light, the second point light source 4b emitting green (G) light, or blue (B) light. It can be set as the 3rd point light source 4c which emits.

  In the first embodiment, the LED that emits red, green, or blue monochromatic light has higher luminous efficiency than the LED that emits white light, and the color filter used in the liquid crystal display device transmits red, green, and blue light. By combining the characteristics and the emission spectrum of the LED, a display device with high color reproducibility can be obtained. Moreover, the hue of the emitted light from the planar light source device can be easily changed by independently controlling the LEDs for each color.

  The point light source substrate 5 has a rectangular shape. On the point light source substrate 5, the plurality of point light sources 4 are mounted so as to be arranged along the longitudinal direction of the point light source substrate 5. The point light source substrate 5 extends in the longitudinal direction on the outer side (back side) of the bottom surface portion of the casing 1 and is fixed to the outer side of the casing 1.

  In the present invention, the numbers of the first point light source 4a, the second point light source 4b, and the third point light source 4c mounted on the point light source substrate 5 are not necessarily equal. The number of each of the first point light source 4a, the second point light source 4b, and the third point light source 4c is appropriately set so that the light transmitted through the liquid crystal display element can be optimized to a desired chromaticity. Can be selected. For example, as shown in FIG. 4, a plurality of point light sources can be mounted on the point light source substrate 5 in the order of G, B, G, R, G, B, G, and B. Moreover, in this Embodiment, although the point light source 4 group which arranged the some point light source 4 along the longitudinal direction of the bottom face 1a of the housing | casing 1 is arranged in parallel by 2 rows, in this invention, The number of columns can be appropriately selected depending on the luminance obtained from the point light source 4.

  The deflection element 6 is disposed in the reflecting portion 2 on the bottom surface 1 a of the housing 1 so as to include the point light source 4. The deflection element 6 refracts outgoing light toward the bottom surface side of the casing with respect to incident light incident on the incident surface. In particular, as described later, out of the light distribution of incident light incident on the incident surface of the deflection element 6, light having an incident angle with the maximum luminous intensity is directed to the bottom surface 1 a side of the housing 1 on the exit surface of the deflection element 6. It is desirable to be configured to refract.

  The deflection element 6 extends in the longitudinal direction of the casing 1 and is a quadrangular prism whose section increases in thickness from the opening 1b side to the bottom surface 1a side of the casing 1. Yes, it is made of a transparent resin such as acrylic or glass and has a function of transmitting light.

  The deflection element 6 according to the first embodiment includes a bottom surface 1a of the casing 1 on the point light source 4 side, that is, a surface (incident surface) 6a substantially perpendicular to the reflecting portion 2, and a bottom surface of the casing 1. A bottom surface 6b substantially parallel to 1a and a top line of the substantially parallel bottom surface 6b, that is, a top line (a line perpendicular to the plane of the drawing in FIG. 3) 6c at a position away from the light source 6c. A first inclined surface (outgoing surface) 6d having a predetermined inclination angle from the top line 6c to the side opposite to the bottom surface 1a of the housing 1, that is, from the top line 6c to the substantially vertical surface 6a side, which is the incident surface. , And a substantially parallel bottom surface 6b and a top surface 6e facing in parallel.

  The deflection element 6 is provided with a cylindrical depression D1 into which the point light source 4 can be inserted from the substantially parallel bottom surface 6b side so as to contain the point light source 4. The cylindrical recess D1 is composed of a substantially vertical surface 6a of the deflection element 6 serving as a side surface and a circular inner surface 6f facing the upper surface 6e of the deflection element 6 in parallel. In addition, the deflection element 6 includes a diffusion portion in which the surface of the upper surface 6e of the deflection element 6 is processed into an uneven surface along the longitudinal direction of the bottom surface 1a of the housing 1 so as to cover the upper part of the point light source 4 group. 7 is provided. The diffuser 7 can reduce the luminance immediately above the point light source 4.

  In the first embodiment, the surface of the upper surface 6e of the deflection element 6 is formed as a diffusing portion 7, but a metal such as aluminum or silver is deposited on the upper surface 6e of the deflection element 6, Alternatively, a reflective material can be attached to the upper surface 6e of the deflection element 6 to form a reflective portion. When such a reflection portion is used, it is possible to limit the light emitted from the upper surface 6e of the deflection element 6, so that the luminance directly above the point light source 4 can be reduced.

  A plurality of optical sheets (not shown) are disposed on the first diffusion unit 3 in order to effectively use light, and the optical sheet is disposed on the first diffusion unit 3. A liquid crystal display element (not shown) is arranged through sheets.

  The optical sheets have a structure in which a lens sheet is sandwiched between diffusion sheets. In addition, when the luminance needs to be improved, a plurality of lens sheets may be combined in consideration of the direction of the prism of the sheet formed on the surface. In addition, two or more diffusion sheets can be used to improve diffusibility. Furthermore, one lens sheet may or may not be used depending on the light distribution characteristics of the lens sheet. Further, a protective sheet or a polarizing reflection sheet may be used in combination, or neither may be used.

  A liquid crystal display device, which is an example of the display device of the present invention, is a circuit board that drives a liquid crystal display element as display means on the first diffusion portion 3 that is an upper portion of the planar light source device according to the present embodiment ( It can be configured by arranging a liquid crystal display element provided with a not-shown).

  The liquid crystal display element includes a TFT array substrate and a counter substrate in which electrodes and wiring such as a colored layer, a light shielding layer, a thin film transistor (hereinafter referred to as TFT) serving as a switching element, a pixel electrode, and a wiring are formed on an upper or lower substrate. Spacer for holding two substrates at equal intervals, sealing material for bonding two substrates, sealing material for sealing after injecting liquid crystal between two substrates, alignment film for giving initial alignment to liquid crystal In the present invention, since an existing liquid crystal display element is used, the description thereof is omitted here.

  Next, an optical path until the light emitted from the point light source 4 is emitted from the first diffusion unit 3 will be described.

  The red, green, and blue monochromatic light emitted from the first point light source 4a, the second point light source 4b, and the third point light source 4c, which are the point light sources 4, are directly or first reflected. The light is reflected by the portion 2 and is incident on the inner surface 6f of the deflection element 6 or the substantially vertical surface 6a.

  Among these, the light from the point light source 4 incident on the inner surface 6 f of the deflection element 6 reaches the diffusion portion 7 that is the upper surface 6 e of the deflection element 6. The light reaching the diffusing portion 7 is refracted by the uneven surface of the diffusing portion 7 and is emitted from the upper surface 6e in all directions.

  The light from the point light source 4 incident on the substantially vertical surface 6a that is the incident surface of the deflection element 6 is transmitted through the substantially vertical surface 6a of the deflection element 6 and the first inclined surface 6d that is the emission surface. By refracting, the incident light is refracted toward the bottom surface 1a side of the housing 1 and emitted. For this reason, the light which reaches | attains the spreading | diffusion part 3 of the vicinity of a light source, and radiate | emits can be reduced, the bright part of the vicinity of a light source can be improved, and the uniformity of the brightness | luminance of the whole display surface can be improved.

In this embodiment, as described light path with reference to FIG. 5, of the light distribution of light incident on the substantially vertical surface 6a, declination incident light incident angle phi _i luminous intensity is the maximum Control is performed by the element 6 so as to emit light toward the bottom surface 1 a of the housing 1. Here, the refractive index of the deflection element 6 is n (n is larger than the refractive index 1 of air), and the inclination angle of the first inclined surface 6d of the deflection element 6 is θ ₁ (0 <θ ₁ <90 °). And

The light incident on the substantially vertical surface 6a of the deflection element 6 at the incident angle φ _i is refracted at the emission angle α shown in the following equation (1) according to Snell's law.
α = Sin ⁻¹ ((1 / n) × Sinφ _i ) (1)

The light passing through the deflection element 6 is incident on the first inclined surface 6d at an incident angle β (= 90 ° −θ ₁ −α), and is expressed by the following equation (2) according to Snell's law. The light is refracted and emitted from the first inclined surface 6d of the deflection element 8 at the output angle φ _o shown.
φ _o = Sin ⁻¹ (n × Sin β)
= Sin ⁻¹ (n × Sin (90 ° −θ ₁ −α))
= Sin ⁻¹ (n × Sin (90 ° −θ ₁
−Sin ⁻¹ ((1 / n) × Sinφ _i ))) (2)

In order to emit light emitted from the first inclined surface 6d of the deflection element 6 to the bottom surface 1a side of the housing 1, an angle γ (= φ _o − (90 ° −θ _{1) with} respect to the bottom surface 1a of the housing 1 is used. )) May be 0 ° or more.

That is, it is sufficient to satisfy the following inequality (3).
0 ° ≦ γ = φ _o − (90 ° −θ ₁ )
= Sin ⁻¹ (n × Sin (90 ° −θ ₁
−Sin ⁻¹ ((1 / n) × Sinφ _i )) − 90 ° + θ ₁ (3)

Here, the LED which is the point light source 4 controls the directivity of the emitted light by sealing the LED element with a lens-shaped resin. For example, as shown in FIG. 6, the light distribution in which the luminous intensity is maximum when the angle of light emitted from the LED is ± 80 °, with the clockwise direction from the upper vertical direction being positive with respect to the central axis in the arrangement direction of the LED elements. Is used as the point light source 4, the incident angle φ _i at which the luminous intensity is maximum is 10 ° out of the light distribution of incident light incident on the substantially vertical surface 6 a, and the deflection element 6 When the refractive index n is 1.5, the inclination angle θ ₁ of the declination element 6 satisfies θ ₁ <70.05 ° from the inequality (3), and the bright portion in the vicinity of the light source is reduced. In addition, the luminance distribution can be improved.

In order to prevent loss due to total reflection on the first inclined surface 6d of the deflection element 6, it is preferable to satisfy the following inequality (4).
1> n × Sin β = n × Sin (90 ° −θ ₁ −α)
= N × Sin (90 ° −θ ₁
−Sin ⁻¹ ((1 / n) × Sinφ _i )) (4)

In addition, if the incident angle φ _i at which the luminous intensity is maximum is 10 ° and the refractive index n of the deflecting element 6 is 1.5 in the light distribution of the incident light incident on the substantially vertical surface 6a, the deviation is as follows. The inclination angle θ ₁ of the corner element 6 is θ ₁ > 41.55 ° from the inequality (4). By satisfying such θ ₁ , the incident light having the maximum luminous intensity in the distribution of incident light incident on the substantially vertical surface 6 a is totally reflected on the first inclined surface 6 d of the deflection element 6. Therefore, the incident light can be efficiently emitted from the first inclined surface 6d.

  The light emitted from the first inclined surface 6d of the declination element 6 to the bottom surface 1a side of the housing 1 is reflected by the first reflecting portion 2, and is emitted from the light source to the internal space of the housing 1 (on the light source side). Propagate light toward.

  Next, the light incident on the first diffusion unit 3 is divided into a light component that is transmitted through the first diffusion unit 3 and a light component that is reflected by the particles in the first diffusion unit 3. Among these, the component light reflected to the bottom surface 1 a side of the housing 1 is reflected by the first reflecting portion 2 and enters the first diffusing portion 3 again. Further, the component light incident on and transmitted through the first diffusing portion 3 is radiated in all directions from the surface of the first diffusing portion 3 on the liquid crystal display element side.

  The light emitted from the upper surface of the first diffusing unit 3 passes through optical sheets such as a diffusing sheet, a protective sheet, a lens sheet, or a prism sheet, and enters the liquid crystal display element. In the liquid crystal display element, the liquid crystal layer is aligned by turning on or off the voltage by the switching element, so that the light incident on the liquid crystal display element is modulated according to the video signal and displays each color of red, green, or blue.

  As described above, according to the planar light source device according to the first embodiment of the present invention, the declination element 6 refracts the emitted light toward the bottom surface 1a of the housing 1, thereby the first light source near the point light source. The light that reaches and exits the diffusing portion 3 can be reduced, the bright portion near the point light source can be improved, and the luminance uniformity of the entire display surface can be improved. Further, the deflection element 6 refracts light having an incident angle with the maximum luminous intensity in the light distribution of incident light incident on the incident surface of the deflection element 6 toward the bottom surface 1a side of the housing 1, Since a lot of light out of the outgoing light from the deflection element 6 can be made to reach the first diffusion part 3 after being reflected by the first reflection part 2, the propagation distance of the light is increased, and the point light source The bright portion in the vicinity of can be further reduced, and unevenness in luminance and chromaticity on the display surface can be suppressed.

  In addition, by providing the diffusing portion 7 between the point light source 4 and the first diffusing portion 3 immediately above the point light source 4, a first diffusing portion that can occur in a conventional direct-type planar light source device is provided. The occurrence of luminance unevenness in which the luminance of the portion where the point light source 4 is present on the surface 3 is higher than that of the surrounding portion can be suppressed.

Embodiment 2
FIG. 7 is a partial cross-sectional view seen from the longitudinal direction of the planar light source device according to Embodiment 2 of the present invention. As shown in FIG. 7, the second embodiment is different from the first embodiment only in that a part of the deflection element 9 is composed of a plurality of first inclined surfaces 9d and opposing surfaces 9g. The description of the same or corresponding parts as in FIGS. 1 to 5 is omitted, and the same operational effects as those of the first embodiment are obtained except for the operational effects of the deflection element 9 described later.

  The deflection element 9 according to the second embodiment includes a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 9a substantially perpendicular to the reflecting portion 2, and a bottom surface of the housing 1. A bottom surface 9b that is substantially parallel to 1a, a plurality of opposing surfaces 9g that are substantially parallel to the bottom surface 1a of the housing 1, and a top line of each of the substantially parallel bottom surface 9b and the plurality of opposing surfaces 9g (see FIG. In FIG. 7, a plurality of first inclined surfaces (emission surfaces) 9d having a predetermined inclination angle from the line 9c perpendicular to the paper surface 9c to the substantially vertical surface 6a side as the incident surface, and parallel to the substantially parallel bottom surface 9b. And an upper surface 9e facing the surface.

  In addition, a cylindrical recess D2 into which the point light source 4 can be inserted from the parallel bottom surface 9b side is provided inside the deflection element 9 so as to include the point light source 4. The cylindrical recess D2 is composed of a substantially vertical surface 9a of the deflection element 9 serving as a side surface and a circular inner surface 9f facing the upper surface 9e in parallel. In the second embodiment, the inner surface 9f and the upper surface 9e are constituted by the cylindrical recess D2, but in the present invention, the inner surface 9f and the upper surface 9e are omitted by making the recess D2 a through hole. You can also.

In the first embodiment, as shown in FIG. 3, it is composed of the deflection element 6 that is a single prism. For example, when the luminous intensity of the emitted light from the point light source is high in the vertical upward direction, that is, When the incident angle φ _i is close to 90 degrees or the like and a small tilt angle θ ₁ is required, the thickness of the deflection element 6 in the width direction is increased. For this reason, in order to obtain sufficient luminance, when it is necessary to arrange a large number of rows of the point light sources 4 along the longitudinal direction of the bottom surface 1a of the housing 1, the number of rows that can be arranged is limited. Will occur. However, in the second embodiment, as shown in FIG. 7, the deflection element 9 can be made thin by using a configuration having a prism array in which a plurality of prisms are repeatedly arranged. it can. For this reason, as compared with the deflection element 6 formed of a single prism, a large number of columns of the point light sources 4 can be arranged.

  In the second embodiment, when the light from the point light source 4 is incident on the opposing surface 9g of the deflection element 9, the light is emitted in a direction different from the case where the light is incident on the first inclined surface 9d. Loss. In order to suppress this loss as much as possible, the area of the first inclined surface 9d is increased so as to reduce the light incident on the opposing surface 9g. That is, the opposing surface 9g has a shape close to parallel.

In the second embodiment, each of the first inclined surfaces 9d of the deflection element 9 is formed by a plane having the same inclination angle θ _1. However, in the present invention, the deflection element 6 is projected. It is only necessary that the incident light can be refracted toward the bottom surface 1a of the housing 1, and the shape is not limited to this.

Embodiment 3
8 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 3 of the present invention, FIG. 9 is a sectional view taken along the line CC of FIG. 8, and FIG. 10 is a sectional view taken along the line DD of FIG. is there. The third embodiment is different from the first embodiment only in that the deflection element 6 has the reflecting portion 8 only at a position corresponding to the point light source 4 on the upper surface 6e. About the same or an equivalent part, while abbreviate | omitting the description, there exists an effect similar to Embodiment 1 except the effect by the reflection part 8 mentioned later.

  Reflector 8 in the third embodiment deposits a metal such as aluminum or silver only on a position corresponding to a position directly above point light source 4 on upper surface 6e of declination element 6, or attaches a reflective material. It is formed by.

  In Embodiment 3 of the present invention, as shown in FIGS. 8 to 10, a position corresponding to a position directly above the point light source 4 on the upper surface 6 e of the deflection element 6, for example, from the opening 1 b side of the housing 1 is used. When the top surface 6e of the corner element 6 is viewed, the circular reflecting portion 8 is provided only at a position substantially coinciding with the inner surface 6f of the deflection element 6, so that direct light from the point light source 4 is reflected by the reflecting portion 8. It is blocked and an increase in luminance at a position corresponding to a position directly above the point light source 4 can be suppressed. This is because when the point light source 4 having a light distribution with the maximum luminous intensity is used in the vertical direction, as in the first and second embodiments, the polarization unit having the diffusion portion 7 on the entire upper surface 6e of the deflection element 6 is used. Compared with the corner element 6, the uniformity of luminance between the portion directly above the point light source 4 and the other portions can be further enhanced.

  In the third embodiment, the declination element 6 has the circular reflecting portion 8 at a position corresponding to the point 6 directly above the point light source 4 in the upper surface 6e. However, instead of the reflecting portion 8, By making the surface of the upper surface 6e of the deflection element 6 at a position corresponding to the position directly above the point light source 4 into a diffusing portion, the luminance directly above the point light source 4 can be reduced. .

Embodiment 4
11 is a plan view showing a schematic configuration of a surface light source device according to Embodiment 4 of the present invention, FIG. 12 is a cross-sectional view taken along the line EE of FIG. 11, FIG. 13 is a cross-sectional view taken along the line FF of FIG. FIG. 14 is an explanatory diagram showing an optical path that may occur when light passing through the deflection element is totally reflected by the second inclined surface. As shown in FIGS. 11 to 14, in the fourth embodiment, the declination element 10 has only the second inclined surface 10e instead of providing the diffusing portion or the reflecting portion on the upper surface 6e. The description of the same or corresponding parts as in FIGS. 1 to 5 is omitted, and the same functions and effects as those of the first embodiment are obtained except for the functions and effects of the second inclined surface 10 e described later.

The declination element 10 according to the fourth embodiment includes a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 10a substantially perpendicular to the reflecting portion 2, and a bottom surface 1a of the housing 1. A predetermined inclination angle θ ₁ from the substantially parallel bottom surface 10b and a top line (a line perpendicular to the paper surface in FIG. 13) 10c of the substantially parallel bottom surface 10b to the substantially vertical surface 6a side as the incident surface. An imaginary line L1 connecting the first inclined surface (outgoing surface) 10d and the tips of the light emitting portions (first, second, and third point light sources) of the plurality of arranged point light sources 4 vertically upward And a second inclined surface 10e having a predetermined inclination angle toward the left and right first inclined surfaces 10d, which are the emission surfaces, from the reference line L2 translated in parallel. Further, the deflection element 10 is provided with a cylindrical recess D3 into which the point light source 4 can be inserted from the substantially parallel bottom surface 10b side so as to contain the point light source 4. The cylindrical recess D3 includes a substantially vertical surface 10a serving as a side surface and a circular inner surface 10f that is parallel to a substantially parallel bottom surface 10b of the deflection element 10.

  In the fourth embodiment, the direct light from the point light source 4 is totally reflected by the second inclined surface 10e of the deflection element 10, so that the light is transmitted from the second inclined surface 10e to the outside of the deflection element 10. Since the directivity of light can be adjusted efficiently without being emitted and the light can be refracted and emitted by the first inclined surface 10d, the bright portion in the vicinity of the light source can be reduced. Further, since the deflection element 10 is not provided with a diffusing portion or a reflecting portion that causes a reflection loss on the upper surface 6e, it is possible to obtain a planar light source device with high light utilization efficiency.

Here, the refractive index of the deflection element 10 is n (n is larger than the refractive index 1 of air), and the inclination angle of the second inclined surface 10e of the deflection element 10 is θ ₂ (0 ° <θ ₂ < 90 °), when the incident angle to the inner surface 10f of the deflection element 10 is φ ₁ (−90 ° <φ ₁ <90 °), the second inclined surface 10e of the deflection element 10 is totally reflected. Satisfies the following inequality (5).
1 <n × Sinβ ₁ = n × Sin (θ ₂ + α ₁ )
= N × Sin (θ ₂
+ Sin ⁻¹ ((1 / n) × Sinφ ₁ )) (5)

It should be noted that most of the light that directly reaches the second inclined surface 10e from the point light source 4 is light perpendicularly incident on the inner surface 10f of the declination element 10, that is, the incident angle φ ₁ and the emission angle α _{1 at the} inner surface 10f are 0. The incident angle with respect to the second inclined surface 10e is larger than that of the light at °. Therefore, when the incident angle φ _{1 on} the inner surface 10f is 0 °, most of the light can be efficiently controlled by total reflection by satisfying the inequality (5) described above. Therefore, the inclination angle θ ₂ is determined so as to satisfy the following inequality (6).
1 <n × Sinθ ₂
∴ θ ₂ > Sin ⁻¹ (1 / n) (6)

For example, if the refractive index n of the deflection element 8 is 1.5, the inclination angle θ ₂ of the deflection element 8 is θ ₂ > 41.81 ° from the inequality (6). By satisfying this θ ₂ , the direct light from the point light source 4 reaching the second inclined surface 10e of the deflection element 10 undergoes total reflection at the second inclined surface 10e, and the light is efficiently converted into the first light. The light can be emitted from the inclined surface 10d.

Embodiment 5
15 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 5 of the present invention, FIG. 16 is a sectional view taken along line GG in FIG. 15, and FIG. 17 is a sectional view taken along line HH in FIG. is there. As shown in FIGS. 15 to 17, in the fifth embodiment, only the deflection element 13 and the second diffusing portion 14 are different from the first embodiment, and the same or corresponding parts as in FIGS. The explanation is omitted, and the same operational effects as those of the first embodiment are obtained except for the operational effects of the second diffusion unit 14 described later.

The declination element 13 according to the fifth embodiment includes a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 13a substantially perpendicular to the reflecting portion 2, and a bottom surface 1a of the housing 1. A predetermined inclination angle θ ₁ is formed from a substantially parallel bottom surface 13b and a top line of the substantially parallel 13b (a line in the direction perpendicular to the paper surface in FIG. 17) 13c to the substantially vertical surface 13a side as the incident surface. It comprises a first inclined surface 13d and an upper surface 13e that faces the substantially parallel bottom surface 13b in parallel.

  The declination element 13 is a quadrangular prism that extends in the longitudinal direction of the housing 1 and has a trapezoidal cross section in which the thickness increases from the opening 1b side to the bottom surface 1a side of the housing 1. It is made from transparent resin such as acrylic or glass and has a function of transmitting light. Further, a cylindrical through hole D4 into which the point light source 4 can be inserted from the substantially parallel bottom surface 13b side is provided.

  The second diffusing portion 14 extends in the longitudinal direction of the housing 1 and is disposed on the upper surface 13e so as to seal the through hole D4 of the deflection element 13. The point light source 4 is included in the second diffusion portion 14 and the substantially vertical surface 13a of the deflection element 13 which is the side surface of the cylindrical through hole D4.

  The second diffusion portion 14 is made of a resin plate such as acrylic (PMMA), polyethylene terephthalate (PET), or polycarbonate (PC), or a glass substrate, and has a function of transmitting light. In addition, a reflecting material can be mixed in the second diffusing portion 14 or the surface can be roughened to have a function of diffusing incident light.

  It is relatively troublesome to give two characteristics to one member by adding a function of diffusing light to a part of a declination element having a function of declining light as in the first embodiment. is there. However, in the fifth embodiment, by configuring the diffusing section with the second diffusing section 14 which is a member different from the declination element, it is possible to combine two members having different characteristics and obtain desired characteristics. .

  In the fifth embodiment, a group of point light sources 4 in which a plurality of point light sources 4 are arranged along the longitudinal direction of the bottom surface 1a of the housing 1 is used as one set, and the point light source 4 group and the second light source 4 The second diffusion portion 14 is provided so as to correspond to the diffusion portion 14 on a one-to-one basis, but the second diffusion portion 14 is a single sheet having a size substantially equal to the opening 1b of the housing 1. It is good also as a spreading | diffusion part. Thereby, the number of parts of the 2nd spreading | diffusion part 14 can be reduced, and the assembly workability | operativity of a planar light source device improves.

  In the fifth embodiment, the declination element 13 and the second diffusion portion 14 are combined to obtain desired characteristics. However, instead of the second diffusion portion 14, aluminum or silver is easily reflected. What applied the coating material which reflects easily to the surface, such as a metal plate or a resin-made sheet | seat, can also be used as a 2nd reflection part. When this second reflecting portion is used, it is possible to limit the emitted light directly above the point light source 4, so that the luminance directly above the point light source 4 can be reduced.

  Further, instead of the second diffusing portion 14, a substrate made of a transparent resin such as acrylic or glass is used, and the circular diffusion is performed only at a position corresponding to the point light source 4 directly above the upper surface of the substrate. A substrate on which an inclined surface such that direct light from a light source is totally reflected is processed on the upper surface of the substrate using a substrate formed with a transparent portion such as acrylic or glass, or a substrate on which a transparent portion or a reflective portion is formed. By doing so, the luminance directly above the point light source 4 can be reduced.

Embodiment 6
18 is a plan view showing a schematic configuration of a surface light source device according to Embodiment 6 of the present invention, FIG. 19 is a cross-sectional view taken along the line II of FIG. 18, and FIG. 20 is a cross-sectional view taken along the line JJ of FIG. is there. As shown in FIGS. 18 to 20, in the sixth embodiment, the deflection element 15 has a truncated cone shape and matches the number of the point light sources 4, and each deflection element 15 is a point light source. 4 is different from the first embodiment only in a one-to-one correspondence with FIG. 4, and the description of the same or corresponding parts as in FIGS. Except for the above, the same effects as those of the first embodiment are obtained.

  The declination element 15 in the sixth embodiment has a truncated cone shape, and a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 15a substantially perpendicular to the reflecting portion 2. A bottom surface 15b that is substantially parallel to the bottom surface 1a of the housing 1 and a top surface 15c (a line perpendicular to the plane of the drawing in FIG. 20) of each of the bottom surfaces 15b that are substantially parallel to the incident surface. The first inclined surface 15d having a predetermined inclination angle on the 15a side, and an upper surface 15e facing the substantially parallel bottom surface 15b in parallel. Further, the deflection element 15 is provided with a cylindrical recess D5 into which the point light source 4 can be inserted from the parallel bottom surface 15b side so as to contain the point light source 4. The cylindrical recess D5 is composed of a substantially vertical surface 15a of the deflection element 15 serving as a side surface and a circular inner surface 15f facing the upper surface 15e in parallel. The number of frustoconical deflection elements 15 matches the number of point light sources 4, and each deflection element 15 corresponds to each point light source 4 on a one-to-one basis.

  In addition, the deflection element 15 is formed as a diffusing portion 7 by processing the surface of the upper surface 15e of the deflection element 15 into an uneven surface so as to cover the upper side of the point light source 4, thereby directly above the point light source 4. Luminance can be reduced. In the sixth embodiment, the diffusing portion 7 is provided on the upper surface 15e of the deflection element 15. However, a metal such as aluminum or silver is vapor-deposited on the upper surface 15e of the deflection element 15, or a reflective material is used. A reflection portion may be formed by being attached to the upper surface 15e of the deflection element 15. If this reflecting portion is used, light emitted from the upper surface 15e of the declination element 15 can be restricted, so that the luminance directly above the point light source 4 can be reduced.

  In the sixth embodiment, even when the light distribution of the light emitted from the point light source 4 is different in each point light source 4, the declination element 15 including the point light source 4 is replaced with each point light source 4. Since it is provided independently for each pair, desired light distribution characteristics can be obtained by matching the shape of the deflection element 15 in accordance with the light emission characteristics of the respective point light sources 4 and display. Uniformity of luminance on the surface can be achieved.

  In particular, the first point light source 4a emitting red (R) light, the second point light source 4b emitting green (G) light, and the third point light source 4c emitting blue (B) light. Since the light emitting elements have different light emission characteristics, three types of declination elements 15 corresponding to each color are used, and the same shape declination elements 15 are assigned to the same color, so that the point light source 4 of each color can be used as desired. The light distribution characteristics can be obtained, and the luminance uniformity on the display surface can be achieved.

Embodiment 7
21 is a plan view showing a schematic configuration of a surface light source device according to Embodiment 7 of the present invention, FIG. 22 is a sectional view taken along line KK in FIG. 21, and FIG. 23 is a sectional view taken along line LL in FIG. is there. As shown in FIGS. 21 to 23, the seventh embodiment is different from the sixth embodiment only in that the diffusing portion is composed of the second diffusing portion 14 made of a member different from the deflection element. About the same or an equivalent part as 1-5, while abbreviate | omitting the description, there exists an effect similar to Embodiment 6 except the effect by the 2nd spreading | diffusion part 14 mentioned later.

  The declination element 16 in the seventh embodiment has a truncated cone shape, and a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 16a substantially perpendicular to the reflecting portion 2. From the bottom surface 16b that is substantially parallel to the bottom surface 1a of the housing 1 and the top line 16c of the substantially parallel 16b (a line perpendicular to the paper surface in FIG. 23) to the substantially vertical surface 16a side that is the incident surface. It comprises a first inclined surface 16d having a predetermined inclination angle and an upper surface 16e facing the substantially parallel bottom surface 16b in parallel. Further, a cylindrical through hole D6 into which the point light source 4 can be inserted from the substantially parallel bottom surface 16b side is provided. The number of frustoconical deflection elements 16 coincides with the number of point light sources 4, and each deflection element 16 corresponds to each point light source 4 on a one-to-one basis.

  The second diffusion portion 14 is disposed on the upper surface 16e so as to seal the through hole D6 of the deflection element 16. The point light source 4 is enclosed by the second diffusion portion 14 and the substantially vertical surface 16a of the deflection element 16 which is the side surface of the cylindrical through hole D6.

  As in the sixth embodiment, it is relatively troublesome to give two characteristics to one member by adding a light diffusing function only to a part to a declination element having a function of declining light. is there. However, in the seventh embodiment, by configuring the diffusing portion with the second diffusing portion 14 which is a member different from the declination element, it is possible to obtain desired characteristics by combining two members having different characteristics. .

  In the seventh embodiment, desired characteristics are obtained by combining the deflection element 16 and the second diffusing portion 14, but instead of the second diffusing portion 14, it is easy to reflect aluminum or silver. What applied the coating material which reflects easily to the surface, such as a metal plate or a resin sheet | seat, can be used as a 2nd reflection part. Since the emitted light directly above the point light source 4 can be limited by the second reflecting portion, the luminance immediately above the point light source 4 can be reduced.

  In the seventh embodiment, a plurality of second diffusing portions 14 are used so as to correspond to the respective deflection elements 16, but in the present invention, they are almost the same as the opening 1b of the casing 1. A single diffusion portion having a size of can be used. Further, using a single substrate made of a transparent resin such as acrylic or glass having a size substantially equal to the opening 1b of the housing 1, a portion of the surface of the substrate directly above the point light source 4 is used. It is possible to use a substrate in which a circular diffusing portion or a reflecting portion is formed only at a position corresponding to. Further, the substrate 1 is a single substrate made of a transparent resin such as acrylic or glass having a size substantially equal to the opening 1b of the housing 1, and the surface of the substrate totally reflects direct light from the light source. A substrate on which such an inclined surface is processed can also be used. Thereby, the number of parts of the 2nd spreading | diffusion part 14 can be reduced, and the assembly workability | operativity of a planar light source device can be improved.

Embodiment 8
24 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 8 of the present invention, FIG. 25 is a sectional view taken along line MM in FIG. 24, FIG. 26 is a sectional view taken along line NN in FIG. FIG. 27 is an explanatory diagram showing an optical path that can occur when light passing through the deflection element is totally reflected by the second inclined surface. As shown in FIGS. 24 to 27, in the eighth embodiment, the declination element is implemented only in that it has the second inclined surface 17e instead of having the upper surface provided with the diffusing portion or the reflecting portion. Different from the sixth embodiment, the description of the same or corresponding parts as in FIGS. 1 to 5 is omitted, and the same functions and effects as those of the sixth embodiment are obtained except for the functions and effects of the second inclined surface 17e described later. Play.

The declination element 17 in the eighth embodiment includes a bottom surface 1a of the housing 1 on the point light source 4 side, that is, a surface (incident surface) 17a substantially perpendicular to the reflecting portion 2, and a bottom surface 1a of the housing 1. A predetermined inclination angle θ ₁ is formed from a substantially parallel bottom surface 17b and a top line of the substantially parallel 17b (a line perpendicular to the paper surface in FIG. 26) 17c to the substantially vertical surface 17a side as the incident surface. A predetermined inclination angle θ ₂ with respect to the bottom surface 1 a of the housing 1 is formed on the opposite side of the bottom surface 1 a of the housing 1 from the first inclined surface 17 d and the vertex 19 on the central axis 18 of the point light source 4. A second inclined surface 17e is formed. Further, the deflection element 17 is provided with a cylindrical depression D7 into which the point light source 4 can be inserted from the substantially parallel bottom surface 17b side so as to contain the point light source 4. The cylindrical recess D7 includes a substantially vertical surface 17a serving as a side surface and a circular inner surface 17f parallel to the substantially parallel bottom surface 17b of the deflection element 17. The number of the deflection elements 17 coincides with the number of the point light sources 4, and each deflection element 17 corresponds to the respective point light sources 4 on a one-to-one basis.

  In the eighth embodiment, direct light from the point light source 4 is totally reflected by the second inclined surface 17e of the deflection element 17, so that the light is transmitted from the second inclined surface 17e to the outside of the deflection element 17. Since the directivity of light can be adjusted efficiently without being emitted and the light can be refracted and emitted by the first inclined surface 17d, the bright portion in the vicinity of the light source can be reduced. Further, since the deflection element 17 is not provided with a reflection part or a diffusion part that causes a reflection loss, a planar light source device with high light use efficiency can be obtained.

Here, the refractive index of the deflection element 17 is n (n is larger than the refractive index 1 of air), and the inclination angle of the second inclined surface 17e of the deflection element 17 is θ ₂ (0 ° <θ ₃ <90 °). ), If the incident angle to the inner surface 17f of the deflection element 17 is φ ₁ (−90 ° <φ ₁ <90 °), in order to totally reflect the second inclined surface 17e of the deflection element 17, It is sufficient to satisfy the following inequality (7).
1 <n × Sinβ ₁ = n × Sin (θ ₂ + α ₁ )
= N × Sin (θ ₂
+ Sin ⁻¹ ((1 / n) × Sinφ ₁ )) (7)

It should be noted that most of the light that directly reaches the second inclined surface 17e from the point light source 4 is light perpendicularly incident on the inner surface 17f of the deflection element 17, that is, the incident angle φ ₁ and the emission angle α _{1 at the} inner surface 17f are 0. The incident angle with respect to the second inclined surface 17e is larger than that of the light at °. Therefore, when the incident angle φ _{1 on} the inner surface 17f is 0 °, most of the light can be efficiently controlled by total reflection by satisfying the inequality (7) described above. Therefore, the inclination angle θ ₂ is determined so as to satisfy the following inequality (8).
1 <n × Sinθ ₂
∴ θ ₂ > Sin ⁻¹ (1 / n) (8)

For example, if the refractive index n of the deflection element 8 is 1.5, the inclination angle θ ₂ of the deflection element 8 is θ ₂ > 41.81 ° from the inequality (8). By satisfying such θ ₂ , the direct light from the point light source 4 reaching the second inclined surface 17e of the deflection element 17 undergoes total reflection on the second inclined surface 17e, and the light is efficiently converted into the first light. The light can be emitted from the inclined surface 17d.

Embodiment 9
FIG. 28 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 9 of the present invention, and FIG. 29 is a cross-sectional view taken along the line PP in FIG. As shown in FIGS. 28 to 29, in the ninth embodiment, only the point where the protrusion 2 a is provided on the first reflecting portion 2 between the group of point light sources 4 and in the vicinity of the side surface of the housing 1 is implemented. Different from the eighth embodiment, the description of the same or corresponding parts as in FIGS. 24 to 27 is omitted, and the same operational effects as in the eighth embodiment are obtained except for the operational effects of the protrusion 2a described later.

  In the ninth embodiment, a plurality of point light sources 4 arranged along the longitudinal direction of the bottom surface 1a of the casing 1 are arranged in a group, and a plurality of point light sources 4 are arranged side by side. A protrusion 2a is provided on the first reflecting portion 2 in the vicinity of the side surface.

  As shown in FIG. 28, the protrusion 2a is provided continuously over the entire length of the bottom surface 1a, so that the light is uniformly distributed regardless of the position in the length direction. Can be reflected to the side. In the present invention, the protrusions 2a are not limited to be provided continuously, and the protrusions 2a having a short length can be provided continuously or arranged at regular intervals. Further, in the present invention, the number, position, or shape of the protrusions 2a can be appropriately selected so that the desired brightness and chromaticity can be optimized after passing through the liquid crystal display element.

  In the eighth embodiment, since the light incident on the first reflection unit 2 has a small incident angle with respect to the first reflection unit 2, a sufficient reflection angle for reaching the first diffusion unit 3 can be obtained. There may not be. However, in the ninth embodiment, even if the angle of light with respect to the bottom surface 1a of the housing 1 is almost horizontal, the light that is incident on at least the protrusion 2a by the protrusion 2a is the first diffuser 3. Therefore, it is possible to obtain a sufficient reflection angle for reaching the above, and thus, it is possible to suppress a decrease in luminance and to obtain a bright planar light source device.

  In the embodiments so far, the incident surface on the point light source side of the declination element is a surface substantially perpendicular to the bottom surface 1a of the housing 1, but in the present invention, the opening 1b of the housing 1 is formed in the opening 1b. It can be set as the inclined surface which inclines in the direction away from the point light source 4 as it approaches. Thereby, surface reflection on the incident surface of light from the point light source 4 is increased, light emitted from the first diffusion unit 3 in the vicinity of the light source is reduced, and luminance unevenness in the vicinity of the light source is reduced. The color mixture of the first point light source 4a, the second point light source 4b, and the second point light source 4c occurs inside the declination element, and chromaticity unevenness is reduced.

  In the first to fifth embodiments, a depression is provided in the declination element corresponding to each point light source 4, but it may be a continuous groove shape connecting adjacent depressions. Thereby, manufacture of the insertion part of the point light source 4 in a declination element can be made easy.

  Moreover, in Embodiments 1-5, although the cross-sectional shape of the transversal direction of the housing | casing 1 of each declination element is made into the symmetrical shape with respect to the central axis of the point light source 4, for example, the center side of the housing | casing 1 is used. The inclination of the inclined surface may be asymmetrical, for example, closer to the bottom surface than the inclined surface on the side surface 1c side of the housing 1. Thereby, the luminance distribution of the planar light source device can be controlled more precisely.

  In the sixth to ninth embodiments, the cross-sectional shape of each declination element in a plane parallel to the bottom surface 1a of the housing 1 is a circular shape centered on the central axis of the point light source 4, but is not circular. It is good also as a shape, a polygonal shape, etc. Thereby, since the light of the arbitrary directions radiate | emitted from the point light source 4 can be controlled independently, the luminance distribution of a planar light source device can be controlled more precisely.

  Further, in the embodiments so far, the point light sources 4 are arranged along the longitudinal direction of the bottom surface 1a of the housing 1, but the present invention is not limited to this, and the short direction Furthermore, they may be arranged in a diagonal direction, and the arrangement direction can be appropriately determined in accordance with the number of necessary point light sources, a required luminance distribution, and the like.

  As described above, in each embodiment, a deflection element having various shapes, a deflection element having a diffusion part or a reflection part, a deflection element having a second diffusion part or a second reflection part, or a projection part. Although the effect by each member is acquired by using individually the 1st reflection part which has this, the further effect can be anticipated by combining a several kind of member.

  In the above embodiment, the planar light source device and the liquid crystal display device using the planar light source device have been described, but the present invention is not limited to these. For example, instead of the liquid crystal display element described above, if a panel displaying characters and symbols is used, it can be applied to a display device such as a signboard or a guide light.

It is a top view which shows schematic structure of the planar light source device concerning Embodiment 1 of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a LED arrangement | sequence figure which shows an example of the arrangement | sequence of LED. It is a principal part enlarged view for demonstrating the optical path of the light which passes a declination element. It is a light distribution distribution figure which shows the light distribution of the emitted light from LED concerning Embodiment 1 of this invention. It is the fragmentary sectional view seen from the longitudinal direction of the planar light source device concerning Embodiment 2 of this invention. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 3 of this invention. It is CC sectional view taken on the line of FIG. It is the DD sectional view taken on the line of FIG. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 4 of this invention. It is the EE sectional view taken on the line of FIG. It is the FF sectional view taken on the line of FIG. FIG. 14 is an explanatory diagram showing an optical path that may occur when light passing through the deflection element is totally reflected by the second inclined surface. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 5 of this invention. It is the GG sectional view taken on the line of FIG. It is the HH sectional view taken on the line of FIG. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 6 of this invention. It is the II sectional view taken on the line of FIG. It is the JJ sectional view taken on the line of FIG. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 7 of this invention. It is the KK sectional view taken on the line of FIG. It is the LL sectional view taken on the line of FIG. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 8 of this invention. It is the MM sectional view taken on the line of FIG. It is the NN sectional view taken on the line of FIG. It is explanatory drawing which showed the optical path which may occur when the light which passes the inside of a deflection | deviation element is totally reflected by the 2nd inclined surface. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 9 of this invention. It is the PP sectional view taken on the line of FIG.

Explanation of symbols

1 housing
1a Bottom
1b opening
2 1st reflection part
3 First diffusion part
4 Point light source
4a First point light source
4b Second point light source
4c Third point light source
5 Point light source substrates 6, 9, 10, 13, 15 Declination elements, 16, 17
6a, 9a, 10a, 13a Almost vertical surface, 15a, 16a, 17a
6b, 9b, 10b, 13b Almost parallel bottom surface, 15b, 16b, 17b
6c, 9c, 10c, 13c Top line, 15c, 16c, 17c
6d, 9d, 10d, 13d First inclined surface, 15d, 16d, 17d
6e, 9e, 13e Upper surface, 15e, 16e
6f, 9f, 10f, 15f Inner surface
7 Diffusion part
8 Reflector
9g Opposing surface
10e, 17e Second inclined surface
14 Second diffusion part
18 Central axis
19 vertex

Claims (14)

A housing having an opening, a first reflecting portion disposed on the bottom surface of the housing facing the opening, a plurality of light sources disposed on the bottom surface side, and disposed in the opening A planar light source device comprising: a first diffusing portion, wherein the light source is a point light source, and a deflection element including the point light source is disposed on a bottom surface side of the casing. and, polarization angle element, Ri Na is configured to refract the outgoing light to the bottom side of the housing with respect to the incident light entering the polarization angle element,
The declination element is a surface substantially perpendicular to the bottom surface of the housing located on the point light source side, a bottom surface substantially parallel to the bottom surface of the housing, and a top line of the substantially parallel bottom surface At least a first inclined surface having a predetermined inclination angle on a substantially vertical surface side that is the incident surface, and the deflection element extends in a longitudinal direction of the casing, The cross section whose thickness increases from the opening side to the bottom surface side of the housing is a trapezoidal quadrangular prism, and the declination is along the longitudinal direction of the bottom surface of the housing so as to cover the point light source group. A planar light source device, characterized in that a diffusion portion is provided in which the upper surface of an element is processed into an uneven surface . A housing having an opening, a first reflecting portion disposed on the bottom surface of the housing facing the opening, a plurality of light sources disposed on the bottom surface side, and disposed in the opening A planar light source device comprising: a first diffusing portion, wherein the light source is a point light source, and a deflection element including the point light source is disposed on a bottom surface side of the casing. And, the deflection element is configured to refract outgoing light to the bottom surface side of the casing with respect to incident light incident on the deflection element,
The declination element is substantially perpendicular to the bottom surface of the housing located on the point light source side, a bottom surface substantially parallel to the bottom surface of the housing, and the bottom surface of the housing A plurality of substantially parallel opposing surfaces, and a plurality of first inclined surfaces having a predetermined inclination angle from the respective substantially parallel bottom surfaces and tops of the plurality of opposing surfaces to the substantially vertical surface side that is the incident surface. And the deflection element extends in the longitudinal direction of the casing, and the deflection element extends along the longitudinal direction of the bottom surface of the casing so as to cover the top of the point light source group. A planar light source device, characterized in that a diffusion unit is provided in which a surface of an upper surface is processed into an uneven surface. The declination element transmits light having an incident angle having the maximum luminous intensity in the light distribution of incident light incident on the incident surface of the declination element on the bottom surface side of the casing on the exit surface of the declination element. The planar light source device according to claim 1, wherein the planar light source device is configured to be refracted. The refractive index of the deflection element is n (n> 1), the inclination angle of the first inclined surface of the deflection element is θ ₁ (0 ° <θ ₁ <90 °), and the incident surface of the deflection element is When the incident angle at which the luminous intensity is the maximum in the light distribution of incident light is φ _i (−90 ° <φ _i <90 °),
Sin ⁻¹ (n × Sin (90 ° −θ ₁ −Sin ⁻¹ ((1 / n) × Sinφ _i ))) − (90 ° −θ ₁ ) ≧ 0 °
The planar light source device according to claim 1 or 2, wherein: The refractive index of the deflection element is n (n> 1), the inclination angle of the first inclined surface of the deflection element is θ ₁ (0 ° <θ ₁ <90 °), and the incident surface of the deflection element is When the incident angle at which the luminous intensity is the maximum in the light distribution of incident light is φ _i (−90 ° <φ _i <90 °),
n × Sin (90 ° −θ ₁ −Sin ⁻¹ ((1 / n) × Sinφ _i )) <1
The planar light source device according to claim 4, wherein: A plurality of point light source groups in which the plurality of point light sources are arranged in a line are arranged in parallel on the bottom surface of the housing, and the point light source group is arranged so that the deflection element covers the point light source group. planar light source device comprising a diffusion portion, or reflector portion along the arrangement direction claims 1, 2, 3, 4 or 5, wherein. The surface light source device of the declination element is a spreading unit or a reflective portion at the corresponding position directly above the point light source according to claim 1, 2, 3, 4 or 5, wherein. A plurality of point light source groups in which the plurality of point light sources are arranged in a row are arranged in parallel on the bottom surface of the casing, and the deflection element connects a virtual line connecting the tips of the light emitting portions of the point light source groups. A second inclined surface having a predetermined inclination angle with respect to the bottom surface of the housing on a side opposite to the bottom surface of the housing from a reference line translated upward; n (n> 1), where the inclination angle of the second inclined surface is θ ₂ ,
θ ₂ > Sin ⁻¹ (1 / n)
The planar light source device according to claim 1, 2, 3, 4, or 5 . The number of the deflection elements is the same as the number of the point light sources, and each of the deflection elements is arranged in one-to-one correspondence with each of the point light sources. The planar light source device according to 4, 5 or 7 . The number of the deflection elements is the same as the number of the point light sources, and each deflection element is arranged corresponding to each point light source in a one-to-one correspondence, A second inclined surface having a predetermined inclination angle with respect to the bottom surface of the housing from the apex on the central axis of the point light source to the bottom surface of the housing; Where n (n> 1) and the inclination angle of the second inclined surface is θ ₂ .
θ ₂ > Sin ⁻¹ (1 / n)
The planar light source device according to claim 1, 2, 3, 4, or 5 . The planar light source device according to claim 6, 7 or 9, wherein the diffusing section or the reflecting section is a second diffusing section or a second reflecting section made of a member different from the deflection element. The point light source is red, the surface light source device according to claim 7, 8, 9, 10 or 11, wherein the light emitting diodes that emit green or blue monochromatic light. A planar light source device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, and an upper portion of the planar light source device. A display device comprising display means for performing display with emitted light. The display means is a liquid crystal display device is composed of two substrates that sandwich the liquid crystal, according to claim 13 Symbol mounting of a display device and a drive circuit substrate connected to the liquid crystal display device.

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