JP2008089782A - Liquid crystal optical element, its manufacturing method, and strobe unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a strobe unit which has a heart-shaped light distribution pattern (especially, having a planar distribution pattern emphasized in vertical directions) using a high transmissive liquid crystal optical element which can control the spread of the light by changing the application voltage. <P>SOLUTION: In a liquid crystal optical element 11, a liquid crystal 10 is interposed between a pair of glass substrates 2 having transparent electrodes formed on the faces thereof. A prism array 6 having prisms is formed on at least one surface of the glass substrates 2 in contact with the liquid crystal 10. The strobe unit is constituted by arranging a light source below the liquid crystal optical element 11. The refractive index of the liquid crystal layer continuously changes by continuously changing the voltage applied to the liquid crystal optical element 11, and the refractive index difference also continuously changes at the boundary of the liquid crystal layer and the prism. It is possible as a result to continuously control the spread of the light distribution characteristics of the light emitted by the light source and passing through the liquid crystal optical element 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal optical element, a manufacturing method thereof, and a strobe device using the same.

  A conventional strobe device mainly includes an Xe tube serving as a light source, a reflector for directing light emitted from the Xe tube in an irradiation direction, a lens for condensing light from the reflector, and the like. Among them, the lens is usually cut with Fresnel or the like in order to obtain predetermined optical characteristics such as light quantity and light distribution.

  In addition, in order to control the irradiation range of the strobe device, the relative distance between the light source and the lens is changed by moving the lens in the optical axis direction of the light source, so that the light beam emitted through the lens is changed from a parallel light beam to a divergent light beam. A mechanical mechanism that adjusts within the above range is known (for example, see Patent Document 1).

  However, in particular, in a built-in strobe of a camera product such as a DSC (digital still camera) that is becoming smaller in size, it is often not approved for an increase in volume that provides a mechanically movable region. It is extremely difficult to adopt a mechanism.

  In addition, built-in strobes used in compact cameras including DSCs generally have a wide opening width in the left-right direction, so that it is possible to obtain desired light distribution characteristics in the vertical direction by designing an appropriate reflector. Become.

  On the other hand, with respect to the light distribution characteristics in the left-right direction, since the opening width in the up-down direction is narrow, the room for obtaining the desired light distribution is limited by the reflector design, and the light distribution characteristics have to depend on the direct light from the light source. This is also the reason why the width of the opening in the left-right direction cannot be reduced, and also causes a reduction in the degree of freedom in designing camera products.

  As a method for controlling the irradiation range of the strobe, a structure in which a plurality of diffuser plates having different diffusivities can be appropriately exchanged is conceivable.

  In that case, the external strobe is generally larger than the built-in strobe and has a larger light output, so a method of illuminating a wider range than the photographing range with a diffuser plate having a relatively high diffusivity may be adopted. . However, since this method takes time to replace the diffuser, there is a possibility of missing a photo opportunity, and in order to illuminate a nearby main subject and a distant background through a uniform diffuser, A difference occurs in the amount of irradiation light in each of the backgrounds, resulting in an unsuitable photograph.

  The built-in strobe of a compact camera cannot adopt a mounting structure and operation method like an external large strobe because of restrictions on mounting volume and power consumption. Therefore, there are the following light distribution control techniques that do not use a mechanical mechanism.

That is, a strobe diffuser plate that drives a liquid crystal polymer layer in a matrix between a strobe and a subject is arranged, and a strong or weak voltage is applied to the strobe diffuser plate so as to control from a transparent state to a diffused state steplessly. Thereby, a transmission state is selected for a part that requires a large amount of irradiation light within the imaging range, and a diffusion state is selected for a part where a small amount of irradiation is sufficient, thereby realizing a good distribution of irradiation light (for example, , See Patent Document 2).
JP 2002-90822 A JP-A-10-26793

By the way, the conventional flash device using the liquid crystal optical element has the following problems. that is,
(1) Most of conventional liquid crystal optical elements are formed on an alignment film for promoting alignment of liquid crystal molecules on an uneven film (uneven film) formed on a glass substrate. The film had a structure in which a uniaxially oriented alignment film was obtained by performing an alignment process such as rubbing. In this case, the formation of the alignment film requires a high-temperature heating process (180 to 260 ° C., 1 to 2 hours), and therefore the material of the concavo-convex film needs to have heat resistance, so the degree of freedom in material selection is limited. Will be added. Moreover, it is very difficult to perform a uniform alignment treatment on the fine uneven shape, which may cause problems such as alignment failure.
(2) Most conventional liquid crystal optical elements are polarizing systems, and it is necessary to use a polarizing plate as a constituent member or a polarizing laser or the like as a light source. Therefore, when using a polarizing plate, there is a problem that the light use efficiency is reduced and the reliability of the liquid crystal optical element is impaired. When a polarizing laser is used, the laser itself is expensive. There was a problem that the application was limited.
(3) Most of conventional liquid crystal optical elements need to form a transparent electrode made of ITO or the like on an uneven film. In this case, the concavo-convex film may be damaged due to the influence of heat or plasma during the formation of the ITO film, and the shape and transmittance may be adversely affected. If an ITO film is formed at a low temperature to avoid this problem, there arises a problem that the transmittance (particularly, the short wavelength region) of the transparent electrode is deteriorated. If importance is attached to the transmittance of the ITO film, a heat treatment of at least 300 ° C. is required. Further, when patterning the ITO film, the uneven film located under the ITO film may be damaged by the ITO etching solution. In order to avoid this problem, it is conceivable to form a concavo-convex film on the ITO film. In this case, the voltage applied to the liquid crystal layer varies depending on the location due to the concavo-convex film, and the necessary application There is a problem that the voltage becomes high, and such a configuration cannot be employed in applications where a uniform light control state is required.

  Accordingly, the present invention has been made in view of the above problems, and the object of the present invention is to provide a liquid crystal that has high transmittance and can continuously control the spread of transmitted light by changing the applied voltage. An optical element is used to realize a strobe having a heart-shaped light distribution pattern (particularly, a planar light distribution pattern in which light distribution control in the vertical direction is emphasized).

  In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is a liquid crystal optical element in which liquid crystal is sandwiched between a pair of transparent substrates having transparent electrodes formed on opposite surfaces, wherein the transparent A transparent film having a plurality of concavities and convexities facing the opposite surface is provided on the surface of at least one of the substrates that contacts the liquid crystal.

  The invention described in claim 2 of the present invention is characterized in that, in claim 1, the unevenness has a right triangle in cross-sectional shape.

  The invention described in claim 3 of the present invention is characterized in that, in claim 2, the right triangle is formed such that the long side of the right triangle forms an angle with the irradiation axis of transmitted light. Is.

  The invention described in claim 4 of the present invention is characterized in that, in any one of claims 2 and 3, the right triangles are arranged at a pitch of 10 to 100 μm.

  In addition, the invention described in claim 5 of the present invention is the liquid crystal containing layer according to any one of claims 1 to 4, wherein the gap is maintained by a gap control material, and the diameter of the gap control material is Is 4.5 to 100 μm.

  Moreover, the invention described in claim 6 of the present invention is characterized in that, in any one of claims 2 to 5, the unevenness is a linear structure.

  The invention described in claim 7 of the present invention is characterized in that, in claim 6, the linear structure is formed concentrically.

  In addition, in the invention described in claim 8 of the present invention, in any one of claims 1 to 7, any of the transparent substrate, the transparent film, and the transparent electrode is not subjected to liquid crystal alignment treatment. It is characterized by this.

  According to the ninth aspect of the present invention, a transparent substrate is formed by forming a transparent electrode on a transparent substrate, dropping a UV curable resin on the transparent electrode side of the transparent substrate, and dropping the UV curable resin. It is placed on a reinforcing material, pressed by applying a mold to the UV curable resin dropping side of the transparent substrate, and subjected to UV irradiation from the opposite surface side of the UV curable resin dropping side of the transparent substrate. It has the process of hardening cured resin, It is characterized by the above-mentioned.

  An invention described in claim 10 of the present invention includes the liquid crystal optical element according to any one of claims 1 to 8, a light source, a reflection unit, and a control device, wherein the control device Light distribution control of the liquid crystal optical element is performed by controlling the liquid crystal optical element.

  According to an eleventh aspect of the present invention, in the tenth aspect, the irradiation range is expanded by controlling the liquid crystal optical element, and the irradiation range is irradiated when a surface perpendicular to the optical axis of the light source is irradiated. Arbitrary light distribution can be obtained between the light distribution in which the irradiation intensity of the central part and the peripheral part of the light source is substantially equal and the light distribution in which the irradiation light is concentrated in the central part of the irradiation range. It is.

  The invention described in claim 12 of the present invention is characterized in that, in any one of claims 10 and 11, the light source is an LED, particularly an LED having a shell-type package. .

  The liquid crystal optical element of the present invention can continuously control the spread of light transmitted through the liquid crystal optical element by applying a voltage.

  Further, by using such a liquid crystal optical element in the strobe device, a strobe having a heart-like light distribution pattern (particularly, a planar light distribution pattern emphasizing the light distribution control in the vertical direction) without a mechanical operation unit. An apparatus can be realized.

  Further, unlike a general liquid crystal display element, a liquid crystal optical element does not require a polarizing plate, and thus has a high transmittance. Usually, it is 90% or more, and 95% or more can be secured by applying an AR coating.

  Therefore, by using such a liquid crystal optical element in the strobe device, it is possible to realize a strobe device with a large amount of irradiation light (bright).

  The strobe device of the present invention includes a light source, a member that controls the direction of light from the light source (for example, a reflector), a liquid crystal optical element, and a control device that electrically controls the liquid crystal optical element. The optical element sandwiches the liquid crystal between a pair of transparent substrates each having a transparent electrode formed on each of the opposing surfaces, and at least one surface of the transparent substrate in contact with the liquid crystal has a plurality of minute uneven portions formed of a transparent material. Yes.

  When a voltage is applied to the liquid crystal through the transparent electrode by the control device, the alignment of the liquid crystal molecules changes and the refractive index value of the liquid crystal layer changes. Then, the refraction angle of the light transmitted through the interface between the minute transparent uneven portion and the liquid crystal layer also changes (according to Snell's law), and the traveling direction of the light can be changed.

  Therefore, by using the liquid crystal optical element having such a configuration, a strobe device capable of electrically and continuously controlling the irradiation light distribution characteristic of the light emitted from the light source is realized.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 15 (the same parts are given the same reference numerals). In addition, since the Example described below is a suitable specific example of this invention, various technically preferable restrictions are attached | subjected, The range of this invention limits this invention especially in the following description. As long as there is no description of that, it is not restricted to these Examples.

  The manufacturing method of Example 1 is demonstrated with reference to FIG. First, in the step (a), a pair of glass substrates 2 each having a transparent electrode 1 made of ITO are prepared. The specification of the glass substrate 2 is that the film thickness of the transparent electrode 1 is 80 nm, the thickness of the glass substrate is 0.7 mm, and the glass material is blue plate glass.

  Next, in the step (b), a predetermined amount of the UV curable resin 5 is dropped on the surface of the glass substrate 2 on which the transparent electrode 1 is formed, and the UV curable resin 5 is dropped on the glass substrate 2. Is placed on a translucent reinforcing material 3 made of thick quartz or the like. And the metal mold | die 4 is applied from the resin dripping side of the glass substrate 2, and the glass substrate 2 is pressed with the reinforcing material 3 and the metal mold | die 4. FIG.

After that, it is left for 1 minute or more, and when the dropped UV curable resin 5 fills the gap between the glass substrate 2 (or the transparent electrode 1) and the mold 4, 500 mJ / cm ² from the reinforcing material 3 side. The UV curable resin 5 is cured by irradiating with ultraviolet rays. At this time, since the purpose of the ultraviolet irradiation is to cure the UV curable resin 5, the irradiation amount is not so important. However, since the ITO forming the transparent electrode 1 has a property of absorbing ultraviolet rays, if the film thickness of the ITO film changes, the irradiation amount necessary to cure the UV curable resin 5 may also change. Should be careful.

  After the UV curable resin 5 is cured, the glass substrate 2 is removed from the pressed mold 4 and the reinforcing material 3. The state of the glass substrate 2 at this time is shown in FIG. On the surface of the glass substrate 2 on which the transparent electrode 1 is formed, a prism array 6 is formed in which a plurality of prisms 14 having a sawtooth cross section are linearly arranged in parallel by a UV curable resin 5. The cross-sectional shape of each prism 14 is a fine right triangle with a height of 20 μm, apex angle of 90 °, and two base angles of 45 °, and each short side is on the surface of the glass substrate 2. A prism array 6 is formed so as to be positioned. FIG. 3 is a cross-sectional shape of the prism array 6 obtained by a micrograph of the prism array 6 viewed from above and a step meter.

  Next, in the step (c), a main seal containing 2 to 5 wt% of a gap control material 7a at the peripheral portion on the glass substrate 2 on which the transparent electrode 1 made of ITO and the micro prism array 6 made of UV curable resin are formed. The material 8 is applied by screen printing or dispenser.

  The diameter of the gap control material 7a is selected and used so that the thickness of the liquid crystal layer is 5 to 30 μm including the thickness of the base layer of the prism array 6 of 20 to 40 μm and the height of the prism 14 part of 0 to 20 μm. In this example, a plastic ball having a diameter of 75 μm (manufactured by Sekisui Chemical Co., Ltd.) was employed. This was added to the seal material ES-7500 (manufactured by Mitsui Chemicals, Inc.) 4 wt% to obtain the main seal material 8.

  Further, a gap control material 7b is dispersed on the other glass substrate 2 (or the transparent electrode 1). The gap control material 7b employs a plastic ball having a diameter of 15 μm (manufactured by Sekisui Chemical Co., Ltd.) and is sprayed using a dry gap spreader. In the present embodiment, the diameter of the gap control material 7b is 15 μm, but it is desirable that it is in the range of 4.5 to 100 μm.

  Then, the two glass substrates 2 are faced to each other so that each prism array 6 and the gap control material 7b face each other.

  Next, in the step (d), the two glass substrates 2 are overlapped, and heat treatment is performed in a state where pressure is applied from both sides of the glass substrate 2 with a press machine or the like to cure the main sealing material 8. In this example, heat treatment was performed at 150 ° C. for 3 hours to complete an empty cell having a cell thickness of 5 to 30 μm. Although the thickness of the cell gap 9 (cell thickness) varies depending on the shape and size of the prism array 6, the optical performance in the present invention is the difference in refractive index between the prism and the liquid crystal layer at the interface as will be described later. Therefore, the cell thickness hardly affects the optical performance.

  Also, the gap control material 7b dispersed on the glass substrate 2 is mostly prism-like when completed as an empty cell according to a micrograph of the empty cell as viewed from above the prism array 6 and FIG. 4 showing its cross-sectional shape. It can be seen that it fits in the recesses of the array 6.

  Finally, in the step (e), the liquid crystal 10 is vacuum-injected into the cell gap 9 of the empty cell, and then the liquid crystal 10 is sealed by applying an end seal material (not shown) to the liquid crystal injection port. The optical element 11 is completed. A liquid crystal having a positive dielectric anisotropy (Δε) and a refractive index anisotropy (Δn) of 0.298 (manufactured by Dainippon Ink & Chemicals, Inc.) was used.

  In the above manufacturing method, a minute groove for air bleeding may be provided in a mold used in the step of forming the prism array. In addition, the glass substrate overlapping step may be performed in a vacuum. Further, the transparent electrode of the light control portion of the liquid crystal optical element (the portion corresponding to the pixel in the display element) may be a solid pattern on both the substrates or may be patterned. However, when it is desired to provide an electrode terminal on one glass substrate side, it is necessary to perform patterning. In addition, it is likely that the electrodes are positioned at the main seal portion in both glass substrates, which is not preferable from the viewpoint of the reliability of the liquid crystal optical element.

  The liquid crystal optical element completed through the above manufacturing process has a configuration that does not have azimuthal anisotropy by using a liquid crystal of Δε> 0 and adopting an amorphous alignment without performing an alignment treatment. The refractive index of the liquid crystal is substantially equal to that of the prism array made of UV curable resin when a voltage is applied (when liquid crystal responds), and is larger than that of the prism array when no voltage is applied (when liquid crystal is not responding).

  The light distribution variable experiment conducted by combining the liquid crystal optical element manufactured through the above manufacturing process and the LED light source will be described below. As shown in FIG. 5, the experimental method is that a bullet-type LED 12 having a half width of about ± 10 ° is arranged below the liquid crystal optical element 11 and the voltage applied to the liquid crystal optical element 11 is changed with the LED turned on. Thus, the refractive index value of the liquid crystal layer was changed.

  Then, as shown in FIG. 6, when a voltage is applied to the liquid crystal optical element 11 (50 V is applied in this embodiment), the refractive index of the liquid crystal layer 13 becomes small and becomes almost the same as that of the prism array 6. The refractive index difference between the two at the interface of the prism 14 is almost eliminated. Therefore, the light emitted from the LED 12 light source goes straight through the liquid crystal layer 13 and the prism array 6 and is emitted to the outside (light ray L1).

  On the other hand, when no voltage is applied to the liquid crystal optical element 11, the refractive index of the liquid crystal layer 13 becomes larger than that of the prism array 6, and a difference in refractive index between the liquid crystal layer 13 and the prism 14 occurs. Therefore, the light emitted from the LED 12 light source is refracted at the interface between the liquid crystal layer 13 and the prism 14 and is emitted to the outside (light ray L2).

  Accordingly, when the voltage applied to the liquid crystal optical element 11 is continuously changed, the refractive index of the liquid crystal layer 13 is continuously changed, and the refractive index difference between the two at the interface between the liquid crystal layer 13 and the prism 14 is also continuously changed. As a result, it is possible to continuously and variably control the light distribution characteristics of the light emitted from the LED 12 light source and transmitted through the liquid crystal optical element 11 (light ray L3).

  FIG. 7 is a graph showing the light distribution characteristics obtained through the liquid crystal optical element. The vertical axis indicates the light intensity (μW), and the horizontal axis indicates the viewing angle (°) in the array direction of the prism array. The broken line represents the light distribution characteristic when a voltage is applied to the liquid crystal optical element, and the straight line represents the light distribution characteristic when no voltage is applied. That is, a broken line shows the light distribution characteristic approximated to the LED light source, and a straight line shows the light distribution characteristic different from the LED light source obtained by variably controlling the light distribution characteristic of the LED light source.

  From this figure, due to the prism effect of the liquid crystal optical element, an increase in the amount of irradiation light is observed in the region of −40 ° to −15 ° and 15 ° to 40 ° with respect to the light distribution characteristic of the light source, and the light distribution characteristic is variably controlled It was confirmed that it was possible. Thus, by continuously changing the voltage applied to the liquid crystal optical element, it is possible to obtain an intermediate characteristic with respect to the light distribution characteristic represented by a broken line and a straight line.

  (A), (b), and (c) of FIG. 8 are photographs obtained by photographing light distribution patterns when voltages of 0 V, 10 V, and 20 V are applied to the liquid crystal optical element, respectively. From the photograph, it can be seen that a light distribution pattern spreading as the applied voltage decreases is formed.

  In the second embodiment, the shape of a prism array made of a UV curable resin is set as shown in FIG. 9 with respect to the liquid crystal optical element of the first embodiment described above. Specifically, the cross-sectional shape of each prism is a fine right triangle with a height of 20 μm, apex angle of 45 °, and base angles of 45 ° and 90 °, and the long side is transmitted light. An angle is formed with respect to the irradiation axis. The pitch of the prism is 20 μm. Thereby, the cell thickness of the liquid crystal optical element is 5 to 40 μm. Other materials and manufacturing methods are the same as those in the first embodiment. In this embodiment, the pitch of the prism is 20 μm, but it is desirable that it is in the range of 10 to 100 μm.

  Since the optical characteristics of the combination of the liquid crystal optical element of Example 2 and the strobe were verified by simulation, conditions and results will be described.

  FIG. 10 shows the configuration of the liquid crystal optical element and the strobe. An Xe tube 16 is disposed inside the reflector 15 having an arcuate cross section, and the liquid crystal optical element 11 is disposed so as to close the opening of the reflector 15. The direction of the liquid crystal optical element 11 is a direction (depth direction in the drawing) in which the extension direction of the prisms 14 of the prism array 6 formed in the liquid crystal optical element 11 and the longitudinal direction of the Xe tube 16 are the same.

  The refractive indexes of the glass substrate 2 and the prism array 6 were both set to 1.54, the refractive index of the liquid crystal was set to 1.54 when a voltage was applied, and 1.74 when no voltage was applied.

  FIG. 11 and FIG. 12 show the directivity characteristics obtained by the simulation. FIG. 11 shows the directivity characteristics in the array direction of the prism array, and FIG. 12 shows the directivity characteristics in the prism extension direction of the prism array. In each figure, directivity characteristics when a voltage is applied to the liquid crystal optical element and directivity characteristics when no voltage is applied are shown.

  In FIG. 11, the light distribution when no voltage is applied spreads in a heart shape with respect to when the voltage is applied, whereas in FIG. 12, the light distribution when the voltage is applied and when no voltage is applied is hardly changed. As can be seen from this, by attaching the liquid crystal optical element to the strobe with the array direction of the prism array being the vertical direction, it is possible to form an irradiation light distribution pattern that spreads in the vertical direction when the strobe is irradiated.

  The liquid crystal optical element of the present invention exhibits a light distribution characteristic associated therewith by changing a control parameter. FIG. 13 shows the change in the light distribution characteristics in the array direction of the prism array by the liquid crystal optical element when the refractive index is changed from 1.54 to 1.74 using the refractive index of the liquid crystal layer as a parameter. FIG. 14 shows the change in the light distribution characteristics in the array direction of the prism array by the liquid crystal optical element when the apex angle is changed from 90 ° to 140 ° using the apex angle of the prism of the prism array as a parameter. Is.

  FIG. 13 shows that the peak value of the radiant intensity distribution decreases and the radiant intensity distribution widens as the refractive index of the liquid crystal layer increases. That is, the simulation result shows that the refractive index value of the liquid crystal layer is changed by changing the voltage applied to the liquid crystal optical element, and as a result, the radiation intensity distribution (light distribution characteristic) can be controlled.

  Further, it can be seen from FIG. 14 that the peak value of the radiation intensity distribution decreases and the radiation intensity distribution widens as the apex angle of the prisms of the prism array increases. That is, when the refractive index value of the liquid crystal layer of the liquid crystal optical element is made constant, a desired radiation intensity distribution (light distribution characteristic) can be realized by appropriately setting the apex angle of the prisms of the prism array. The simulation results show.

  The prism array formed in the liquid crystal optical element has a shape in which a plurality of prisms having a sawtooth cross section are arranged in parallel in a straight line. FIG. 15 shows the desired light distribution characteristics. Such a plurality of prisms having a sawtooth shape in cross section may be concentrically arranged in parallel. Thereby, the light distribution characteristic spread radially can be obtained.

  As described above, the liquid crystal optical element of the present invention can continuously control the spread of light transmitted through the liquid crystal optical element by changing the applied voltage.

  Further, by using such a liquid crystal optical element in the strobe device, a strobe having a heart-like light distribution pattern (particularly, a planar light distribution pattern emphasizing the light distribution control in the vertical direction) without a mechanical operation unit. An apparatus can be realized.

  Further, unlike the general liquid crystal display element, the liquid crystal optical element of the present invention has a high transmittance because it does not require a polarizing plate, and usually 90% or more, and 95% or more can be secured by applying AR coating. .

  Therefore, by using such a liquid crystal optical element in the strobe device, it is possible to realize a strobe device with a large amount of irradiation light (bright).

  In addition, the liquid crystal optical element of the present invention is a strobe device using a Xe tube or LED as a light source, a video camera, a security camera, an in-vehicle camera, or any other video camera, a digital still camera in general, and a strobe using an LED as a light source. It can be used as a camera-equipped mobile phone, an auxiliary light source for movies, and the like.

  In addition, as light distribution control means, car lamps for ordinary passenger cars, light cars, trucks, buses, etc., motorcycle lamps for motorcycles, bicycles, etc., and general lighting equipment such as indoor lighting, street lights, flashlights, etc. Can be used for

  Furthermore, the optical system can be used in office equipment such as laser printers, scanners, and copiers.

It is a manufacturing-process figure of the liquid crystal optical element of this invention. It is a perspective view of the prism array of the liquid crystal optical element of Example 1 concerning this invention. It is the microscope picture which looked at the prism array of the liquid crystal optical element of Example 1 concerning this invention from the upper part, and its sectional drawing. It is the microscope picture which looked at the liquid crystal optical element of Example 1 concerning this invention from the upper part, and its sectional drawing. It is the schematic which shows the experimental method of the light distribution variable experiment which uses the liquid crystal optical element of Example 1 concerning this invention. It is a fragmentary sectional view which shows the interface vicinity of the liquid crystal layer and prism array of the liquid crystal optical element of this invention. It is the graph which showed the light distribution characteristic obtained through the liquid crystal optical element in the light distribution variable experiment. It is the photograph which image | photographed the light distribution pattern when a voltage is applied to a liquid crystal optical element. It is sectional drawing of the liquid crystal optical element of Example 2 concerning this invention. It is sectional drawing of the strobe device using the liquid crystal optical element of this invention. It is a graph which shows the simulation result of the directivity of the liquid crystal optical element of the present invention. Similarly, it is a graph which shows the simulation result of the directivity of the liquid crystal optical element of the present invention. It is a graph which shows the simulation result of the light distribution characteristic when the numerical value of the parameter of the liquid crystal optical element of this invention is changed. Similarly, it is a graph which shows the simulation result of the light distribution characteristic when the numerical value of the parameter of the liquid crystal optical element of this invention is changed. It is a perspective view of the other prism array concerning the liquid crystal optical element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent electrode 2 Glass substrate 3 Reinforcing material 4 Mold 5 UV curable resin 6 Prism array 7a, 7b Gap control material 8 Main seal material 9 Cell gap 10 Liquid crystal 11 Liquid crystal optical element 12 LED
13 Liquid crystal layer 14 Prism 15 Reflector 16 Xe tube

Claims (12)

  A liquid crystal optical element in which liquid crystal is sandwiched between a pair of transparent substrates on which transparent electrodes are formed on opposite surfaces, and the surface of at least one of the transparent substrates that faces the liquid crystal faces the opposite surface A liquid crystal optical element, wherein a transparent film having a plurality of irregularities is provided.   The liquid crystal optical element according to claim 1, wherein the unevenness has a right triangle shape in cross section.   3. The liquid crystal optical element according to claim 2, wherein the right triangle has an angle with respect to an irradiation axis of transmitted light.   4. The liquid crystal optical element according to claim 2, wherein the right triangles are arranged at a pitch of 10 to 100 [mu] m.   5. The liquid crystal according to claim 1, wherein the layer containing the liquid crystal is maintained at an interval by a gap control material, and the diameter of the gap control material is 4.5 to 100 μm. Optical element.   The liquid crystal optical element according to claim 2, wherein the unevenness is a linear structure.   The liquid crystal optical element according to claim 6, wherein the linear structure is formed concentrically.   The liquid crystal optical element according to claim 1, wherein any of the transparent substrate, the transparent film, and the transparent electrode is not subjected to liquid crystal alignment treatment.   A transparent electrode is formed on the transparent substrate, a UV curable resin is dropped on the transparent electrode side of the transparent substrate, the transparent substrate on which the UV curable resin is dropped is placed on a reinforcing material, and the UV curing of the transparent substrate is performed. A liquid crystal optical system comprising a step of pressing a mold on a resin dropping side and curing the UV curable resin by irradiating UV from the opposite side of the transparent substrate to the UV curable resin dropping side Device manufacturing method.   The liquid crystal optical element according to claim 1, a light source, a reflection unit, and a control device, wherein the liquid crystal optical element is distributed by controlling the liquid crystal optical element with the control device. A strobe device that is controlled.   A light distribution in which the irradiation range is widened by the control of the liquid crystal optical element, and the irradiation intensity at the central portion and the peripheral portion of the irradiation range is substantially equal when the surface perpendicular to the optical axis of the light source is irradiated; The strobe device according to claim 10, wherein an arbitrary light distribution between the light distribution in which the irradiation light is concentrated at the center of the range is obtained.   12. The strobe device according to claim 10, wherein the light source is an LED, particularly an LED having a shell-type package.