Enplas Corporation

Other

Yasuhiro Koike

Yashuhiro Koike

Takayuki Arai

Shingo Ohkawa

Kazuaki Yokoyama

Tsuyoshi Ishikawa

Isamu Kaneko

Masato Nakamura

Toshikazu Kobayashi

Kayoko Watai

Hiromi Sasako

Tatsuhiro Takahashi

Tetsufumi Ohta

Tsunemi Monma

Provided in the present invention are an image pickup lens and a design method thereof which can achieve miniaturization of the system and capable of remarkably improving the optical characteristic with a simple structure. By forming a second face on the image pickup surface side of a lens body into a Fresnel face and unifying a diffraction element with at least a first face on the object face side or the second face on the image pickup surface side of the lens body, it becomes possible to correct the Petzval sum and reduce the curvature of the field so that an excellent image plane can be obtained. Also, due to the color dispersion characteristic of the diffraction element, chromatic aberration can be well corrected. Thereby, the optical characteristic of the image pickup lens can be remarkably improved.

Image pickup lens and design method thereof

A liquid crystal display including includes a surface light source device of side light type for backlighting a liquid crystal panel. A primary light source supplies light to a guide plate. Emission from an emitting face impinges on a polarization separating element through a prism sheet. A polarization component which is directionally corresponding to a transmission polarization plane M is supplied to the liquid crystal panel. Reflection at the polarization separating element provides returning light which is subject to inside reflection by projection rows formed on a back face of the guide plate, thereby causing the guide plate to emit afresh recycling light. This recycling light, which is rich with the polarization component directionally in accordance with transmission polarization plane M , impinges again on the polarization separating element. The projection rows formed on the back face run in a direction (first direction) which is generally vertical with respect to an incidence face of the guide plate while obliquely crossing with respect to both reflection polarization plane M and transmission polarization plane M of the polarization separating element. Projection rows formed on an inner face of the prism sheet run in another direction (second direction) which is generally parallel with respect to the incidence face of the guide plate. The polarization separating element and the prism sheet may be unified.

Surface light source device of side light type and liquid crystal display

In a surface light source device of side light type comprising a light guide plate having two major surfaces providing an emission surface and a back surface and a primary light source for supplying irradiation light containing short-wavelength component (blue component) and long-wavelength component (complementary color component to blue) of visible ray region through an end face of the light guide plate, uniformity in color of irradiation light is improved. This surface light source device of side light type further comprises a color correcting film for suppressing change in color of the irradiation light depending on distance from the end face, disposed in the vicinity of at least one of the two major surfaces. The color correcting film may be ink printed on the light guide plate. In a case in which a sheet-like member is disposed along the emission surface of the light guide plate, the color correcting film may be ink printed on the sheet-like member. The color correcting film may be formed on a sheet-like member disposed along the back surface of the light guide plate. The color correcting film has different response characteristics to short-wavelength component and long-wavelength component contained in the irradiation light.

Surface light source device of side light type

A light incident into a wedge type light scattering conducting element from a light incident surface of the light scattering conducting element is converted into a light flux having a directionality and is output from a light output surface. The output light is input to a wedge type emitting direction characteristic adjusting element arranged with a positional relationship complementary to the light scattering conducting element. A prism shaped irregularity for adjusting a propagating directionality of the light in longitudinal/transverse directions is formed on a light input surface/light output surface of the wedge type emitting direction characteristic adjusting element. The wedge type emitting direction characteristic adjusting element has a weakened scattering power depending on requirements, thereby a degree of directionality sharpness of the light emitted from a surface light source device is adjusted. Various modifications are provided for the light scattering conducting elements, and regions having different scattering powers are combined for various patterns. The device is useful for A backlight source.

Surface light source device

A light regulation element regulates both the travelling direction and diffusion state of a light emitted from a surface light source device. Lights from a cylindrical light source,such as a cold cathode tube is introduced in a light guide,. The light guide,has an emission surface,on the side opposite to a reflection element,, and a light regulation element,is arranged in opposition to the emission surface,. Protrusions,are formed on one surface or both surfaces of the light regulation element,. Coated on the surface on the light emission side of the light regulation element,is a light diffusion layer,. The turbidity of the light diffusion layer,falls within a range from 1900 cm,to 2400 cm,. The light emitted from the emission surface,of the light guide penetrates the light regulation element,, thereby causing the light travelling direction to be regulated. Then, the light whose travelling direction has been regulated penetrates the light diffusion layer,, thereby causing a light diffusion. The light diffusion layer,is formed, for example, by mixing fine particles of a glass having a light penetrability or of a synthetic resin such as acryl and silicone, or fine hollow particles of glass, acryl resin or the like, or air bubbles in a coating material having a light penetrability.

Light regulation device

The present invention is a low-density polyethylene-lamellar silicate composite material, and a manufacturing method thereof.

Method for production of a low density polyethylene-lamellar silicate composite material

Light is supplied into a light incident surface,from a fluorescent lamp L enclosed by a silver foil sheet R, and parallelized illuminating light flux is taken out from a light exit surface,On a back surface,side of a light flux parallelizer,across or without a thin air layer,a polarization converter &Sgr; is disposed. The polarization converter &Sgr; reinforces the polarization function of the surface light source device through polarization conversion action accompanying reflection in the prism. At a position confronting the light exit surface,across an air layer,a polarization separating plate,is disposed. At a further outside, across an air layer,an exit light direction modifier,is disposed. A bright polarized illuminating light flux is emitted from a light exit surface,When applied to a backlight of a liquid crystal display, a liquid crystal display panel is disposed at a further outside of the exit light direction modifier

Surface light source device with polarization function

A surface light source device of side-light type enables concentrated output of illumination light to a frontal direction. A flux having clear directivity is outputted from window portions 1w on an emitting surface 5 of a light guide plate 1 with emitting directivity. This flux is represented by a beam C01 outputted in a direction at an angle of 70.degree.. A flux C02 incident on reflection portions 1r is returned to the light guide plate 1 and is given an opportunity of output from the window portions 1w again. The flux C01 having escaped from the window portions 1w to an air layer AR is obliquely incident on flat regions 14g of a propagation direction characteristics modifier 14, and a degree of parallelization of the flux in a propagation direction is improved. The flux is blocked by the reflection portions 1r from being incident on a notch portion (uneffective area) between the flat regions 14g. After total reflection by a total reflection surface 14b of each projection element 14c, the flux is outputted from a flat outside surface 14h to a frontal direction without degrading the improved degree of parallelization. The projection elements 14c may be two-dimensionally arrayed. A prismatic groove or a cylindrical lens array may be formed on the outside surface 14h to two-dimensionally enhance the degree of parallelization.

Surface light source device of side-light type

The invention is a surface light source device capable of effectively producing polarized illumination light. The output angle of a representative beam C3 representing P-polarized component of output light from an emission surface 5 of the light guide plate 1 is about 75.degree.. Where P-polarization component of representative beam C3 is 100 (reference value), and the S-polarized component is 42.2. Representative beam C3 enters from an air layer AR to a flat surface 24g of a prism sheet 24, and then goes into the inside of prism sheet 24. At this stage the P-polarization component is 89.3 whereas the S-polarization component is 25.5. Beam C3 is incident on a slant surface 24d from its inside at an angle proximating the normal, and propagates into air layer AR between prism sheets 24, 34. Beam C3 impinges on a flat surface 34g of a prism sheet 34 while its corresponding part passes through the inside of prism sheet 34. At this stage its P-polarization component is 83.9 and its S-polarization component is 22.3. Beam C3 enters from the inside of one slope 34d of the prism array at the angle of incidence of 31.degree.. Its greater part is output to external air layer AR as illumination light substantially in the front direction.

Surface light source device outputting polarized frontal illumination

Light is supplied into a light incident surface 2 from a fluorescent lamp L enclosed by a silver foil sheet R, and parallelized illuminating light flux is taken out from a light exit surface 3. On a back surface 4 side of a light flux parallelizer 1, across or without a thin air layer 5, a polarization converter .EPSILON. is disposed. The polarization converter .EPSILON. reinforces the polarization function of the surface light source device through polarization conversion action accompanying reflection in the prism. At a position confronting the light exit surface 3 across an air layer 7, a polarization separating plate 8 is disposed. At a further outside, across an air layer 9, an exit light direction modifier 10 is disposed. A bright polarized illuminating light flux is emitted from a light exit surface 11. When applied to a backlight of a liquid crystal display, a liquid crystal display panel is disposed at a further outside of the exit light direction modifier 10.

A method of generating a dual light flux, and a surface light source device for use in a display with a dual preferential viewing direction. Light of a fluorescent lamp is introduced from a light incidence surface to inside of a wedge shape light scattering guide with exiting directivity. While this light is led toward an end surface, it is emitted from a light outgoing surface as an illuminating light flux with exiting directivity to reach a prism sheet as a primary light flux. V-shape grooves giving a prism vertical angle of 90.degree. are formed to face inward and perpendicular to the lamp on the inner surface of the prism sheet, while V-shape grooves giving a prism vertical angle 64.degree. are formed parallel to the lamp on the outer surface of the prism sheet.

Surface light source device of dual light flux generation

A polarization converter P free from any particular limitation in the polarization direction of incident light or wavelength dependence, and large in the degree of freedom of selection of material is composed of polarization conversion unit P1, its united block, or combination or the like. P1 is composed of blocks of one body shape uniting three triangular columnar volume region elements having both ends in right-angled isosceles triangular form so that axial directions of triangular columns corresponding to the elements respectively may be directed in three mutually orthogonal directions. When a linear polarized light L enters vertically to surface 1a, its propagation route is in the sequence of incident point Q.fwdarw.total reflection point R1.fwdarw.total reflection point R2.fwdarw.total reflection point R3.fwdarw.exit point Q'. The incident ray L and exit ray L' are parallel to each other. The polarization direction is preserved at point R1, but is converted 90.degree. at R2, and preserved at R3 to be emitted out as L'. The polarization direction of L' is orthogonal to the polarization direction of L. Whichever the polarization direction of L may be, similar polarization conversion action is exhibited. Multiple polarization conversion units P1 or united blocks are optically and mechanically coupled with a thin substrate region made of optical material, and a polarization converter of sheet form is presented (Representative drawing) FIG. 1.

Polarization converter

A wedge shaped parallelized light flux element made of a light scattering guide of an emitting directionality has a specified ranged effective scattering irradiation parameter and correlation distance 'a'. A light incident into the parallelized light flux element from a fluorescent lamp arranged facing a light incident surface of the parallelized light flux element is emitted from a light output surface as a parallelized light flux G1 by composite factors including forward scattering of the inside, repeated reflection on wedge shaped two sides, critical angular condition and boundary face transmittance for the light output surface. A total amount of parallel light flux G1 emitted from the parallel light flux emitting section F is reflected on a two side prism surface of two prism reflection element PR thereby being converted into sectional area enlarged light fluxes G2 and G3. They are incident on a liquid crystal panel LP through a light diffusion plate DF, and utilized as a backlight. Reflective appearance of a light supply source for supplying a light to the light scattering guide is prevented by forming a reverse slope portion or the like on back surface of the light output surface in adjacent to the light incident surface of the parallelized light flux element.

Growing community of inventors

Kasukabe, Japan

Takayuki Arai