JP2013073862A - Lighting system and driving method of lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system capable of improving diffusion or scattering performance of illumination light at a low cost, and a driving method of the lighting system.SOLUTION: The lighting system is provided with a light source, an optical element which diffuses or scatters light emitted from the light source, and a reflector which reflects the light passing the optical element toward the direction of the optical element. The light emitted from the light source is made to pass the optical elements several times and then is emitted as illumination light. Thereby, with a simple structure comprising the light source, the optical element, and the reflector, the performance of diffusion or scattering of illumination light emitted from the lighting system can be improved at a low cost.

Description

  The present disclosure relates to a lighting device and a driving method of the lighting device.

  As a kind of lighting device, a light emitting device is known that uses a liquid crystal lens and has a function capable of electrically controlling the path of light emitted from a light source by a voltage applied to an electrode film of the liquid crystal lens (for example, , See Patent Document 1).

JP 2005-317879 A

  In the prior art described in Patent Document 1, since the lens efficiency is poor because the liquid crystal lens acts as a lens only on a certain direction of polarized light, the lens efficiency is improved by further overlapping the lens on the liquid crystal lens. I am trying. However, the cost increases as the number of lenses increases. In addition, since the light emitted from the light source is transmitted through the lens as it is and is used as illumination light, the illumination light diffusion or scattering performance is low.

  Therefore, an object of the present disclosure is to provide a lighting device and a driving method of the lighting device that can improve the performance of diffusion or scattering of illumination light at low cost.

In order to achieve the above object, a lighting device of the present disclosure is provided.
light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
With
The light emitted from the light source is an illumination device that is emitted as illumination light after passing through the optical element a plurality of times.

Alternatively, a method for driving the illumination device of the present disclosure for achieving the above object is as follows.
light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
In driving a lighting device comprising:
This is a driving method of an illuminating device that emits light emitted from a light source as illumination light after passing through an optical element a plurality of times.

  In the illumination device having the above-described configuration or the driving method of the illumination device, the illumination device is a reflective illumination device by including a reflector that reflects light that has passed through the optical element. The reflector reflects the light that has passed through the optical element toward the direction of the optical element. As a result, the light emitted from the light source passes through the optical element at least twice, that is, the forward path through which the light passes through the optical element and the return path through which the light reflected by the reflector passes through the optical element. It will be.

  According to the illumination device of the present disclosure or the driving method of the illumination device of the present disclosure, since the light emitted from the light source passes through the optical element a plurality of times due to the reflection type illumination device, the transmission type Compared with the illumination device, the performance of diffusion or scattering of illumination light can be enhanced at a low cost.

1 is a cross-sectional view illustrating a configuration of a lighting device according to Example 1. FIG. It is a figure which shows the behavior of the light in the illuminating device based on Example 1 when a liquid crystal lens is an OFF state (A), and when a liquid crystal lens is an ON state (B). It is sectional drawing which shows the structure of the illuminating device which concerns on Example 2. FIG. It is a figure which shows the behavior of the light in the illuminating device based on Example 2 when a liquid crystal lens is an OFF state (A), and when a liquid crystal lens is an ON state (B). FIG. 6 is a cross-sectional view illustrating a configuration of a lighting device according to a third embodiment. It is a figure which shows the behavior of the light in the illuminating device based on Example 3 when a liquid crystal lens is an OFF state (A), and when a liquid crystal lens is an ON state (B). It is sectional drawing which shows the structure of the illuminating device which concerns on Example 4. FIG. It is a figure which shows the behavior of the light in the illuminating device which concerns on Example 4 when a liquid crystal lens is an ON state.

Hereinafter, the present disclosure will be described based on embodiments with reference to the drawings. The present disclosure is not limited to the embodiments, and various numerical values and materials in the embodiments are examples. In the following description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted. The description will be given in the following order.
1. 1. General description of lighting device and driving method of lighting device of present disclosure Example 1
3. Example 2
4). Example 3
5. Example 4

[Description of Lighting Device and Lighting Device Driving Method of the Present Disclosure, and General]
An illuminating device of the present disclosure includes a light source, an optical element that diffuses or scatters light emitted from the light source, and a reflector that reflects light that has passed through the optical element toward the direction of the optical element. Is emitted as illumination light after passing through the optical element a plurality of times. That is, the illumination device of the present disclosure has a configuration of a reflective illumination device by including a reflector that reflects light that has passed through the optical element.

  The light emitting element used as the light source is not particularly limited. As the light emitting element (that is, the light source), a known light source such as an LED (light emitting diode), EL (electroluminescence), or a light bulb can be used. The directivity of the light source does not matter. The light source may be a point light source or a surface light source.

  The optical element that diffuses or scatters incident light is not particularly limited. As this optical element, an optical element having polarization dependency is preferably used. Examples of the optical element having polarization dependence include a liquid crystal lens and a scattering type liquid crystal element. A liquid crystal lens is a type of lens that utilizes the fact that when a voltage is applied to a liquid crystal, the apparent transmittance of the liquid crystal changes according to the applied voltage. The scattering type liquid crystal element is an element that performs switching in a light scattering state and a non-scattering state (transmission state).

  Examples of the scattering liquid crystal element include a polymer dispersed liquid crystal (PDLC) and a dynamic scattering mode (DSM) liquid crystal element. The polymer dispersion type liquid crystal element is an element that controls light transmission by scattering intensity. The dynamic scattering type liquid crystal element is an element that controls the light / dark state of display using light scattering caused by turbulent liquid crystal molecules.

  The reflector is not particularly limited. A well-known reflector (mirror) etc. can be used as a reflector. The shape of the reflecting surface (that is, the mirror surface) of the reflector (or reflector) is not particularly limited. The reflecting surface of the reflector may be a plane mirror, a concave mirror, or a convex mirror.

  The reflecting surface (mirror surface) of the reflector is preferably surface-treated so as to cause depolarization. Specifically, it is desirable to form with a material or roughness that causes depolarization. Here, “depolarization” refers to depolarization by converting a state having only specific polarization into a state in which various polarizations are mixed.

  The number of reflectors is not particularly limited. That is, the number is not limited to one and may be plural. In the case of a single reflector, the light emitted from the light source is transmitted through the optical element twice in total, the forward path through which the light passes through the optical element and the return path through which the light reflected by the reflector passes through the optical element. Will pass.

  In the case where there are a plurality of reflectors, the reflector is a first reflector provided on one element surface side of the optical element and a second reflector provided on the other element surface side of the optical element. The structure which consists of two can be illustrated. At this time, from the viewpoint of matching the optical axis direction of the illumination light (emitted light) with the optical axis direction of the light emitted from the light source, the reflective surface of the first reflector and the reflective surface of the second reflector are parallel. A flat surface is desirable.

  When there are two reflectors, the light emitted from the light source is the first time that the light passes through the optical element and the second time that the first light is reflected by the first reflector and passes through the optical element. Then, the second light passes through the optical element a total of three times, the third time when the light is reflected by the second reflector and passes through the optical element. By further increasing the number of reflectors, the number of times that the light emitted from the light source passes through the optical element can be further increased.

  It is preferable to arrange a retardation plate between the optical element and the reflecting surface of the reflector. When the phase difference plate is disposed, the reflecting surface of the reflector is not subjected to a surface treatment that causes depolarization. A λ / 4 plate (λ is a wavelength) is preferably used as the retardation plate. The λ / 4 plate is a birefringent element (phase plate) that generates a phase difference of π / 2 (= 90 degrees) between orthogonal polarization components.

  The λ / 4 plate is preferably a broadband retardation plate that gives a constant phase difference with respect to a wavelength in a predetermined band (wide band), in other words, a broadband retardation plate that gives a constant phase difference at any wavelength. . By using a broadband λ / 4 plate, the wavelength dependence can be reduced.

From the viewpoint of reducing the size of the main body of the lighting device and simplifying the handling, it is preferable that the light source, the optical element, and the reflector are housed in a package to form one package. When a retardation plate is used, it is preferable that the retardation plate is also housed in the same package together with the light source, the optical element, and the reflector so as to make one package.

  According to the illumination device having the above-described configuration or the driving method of the illumination device, the light emitted from the light source is emitted as illumination light after passing through the optical element a plurality of times because the illumination device is of a reflective type. Therefore, the diffusing or scattering performance of the illumination light can be improved as compared with the transmissive type. In addition, since the light source, the optical element, and the reflector have a simple configuration, the present lighting device can be provided at low cost.

  The illumination device of the present disclosure can be used as a general illumination device, an illumination device (light source device) for a monitoring camera, an illumination device for a camera such as a flash, and the like. However, it is not limited to these uses. For example, it can also be used as a lighting device for automobiles.

  Hereinafter, specific examples of the illumination device according to the embodiment using a liquid crystal lens as an optical element that diffuses or scatters light emitted from the light source will be described.

[Example 1]
FIG. 1 is a cross-sectional view illustrating the configuration of the illumination device according to the first embodiment. 1A is a cross-sectional view of a lighting device, and FIG. 1B is a cross-sectional view of a liquid crystal lens.

In FIG. 1A, the illumination device 10 _{A according to the} first embodiment includes a light source 11, a liquid crystal lens 12 that is an optical element having polarization dependency, and a reflector 13. The light source 11 includes an LED, an EL, a light bulb, and the like.

  Here, a point light source is used as the light source 11. However, the light source 11 is not limited to a point light source, and a surface light source that emits parallel light may be used. The liquid crystal lens 12 has two transparent substrates and a liquid crystal layer made of a liquid crystal material sealed between the two transparent substrates, and the lens performance such as the degree of diffusion is variable according to the voltage applied between the liquid crystal layers. It has become.

  Specifically, as shown in FIG. 1B, the liquid crystal lens 12 includes, for example, two glass substrates 121 and 122 which are transparent substrates, and a liquid crystal material is sealed between the glass substrates 121 and 122. And a liquid crystal layer 123. The two glass substrates 121 and 122 are coated with antireflection. The liquid crystal layer 123 is made of, for example, a nematic liquid crystal having a homogeneous molecular arrangement.

  On the inner surfaces of the two glass substrates 121 and 122, for example, a transparent electrode of a metal oxide film such as an indium oxide ITO film to which tin is added is formed. Specifically, a transparent electrode 124 for forming an electrical ground plane is formed on one inner surface of the two glass substrates 121 and 122 over the entire surface of the glass substrate. Further, on the other inner surface of the two glass substrates 121 and 122, a band-shaped transparent electrode 125 for giving a necessary electric field distribution to the liquid crystal layer 123 is formed in an annular shape, for example.

  In the liquid crystal lens 12 having the above configuration, when a voltage is applied between the upper and lower transparent electrodes 124 and 125 sandwiching the liquid crystal layer 123, a nematic having a birefringence (that is, a difference in refractive index between the major axis and the minor axis of liquid crystal molecules). The liquid crystal tilts along the electric field. That is, for light having linearly polarized light in a direction parallel to the liquid crystal molecules (major axis direction), the liquid crystal layer 123 is equivalent to a medium having a locally different refractive index distribution depending on the voltage distribution. . Therefore, spatial wavefront modulation or phase modulation corresponding to the in-plane distribution of the applied voltage of the liquid crystal is applied to the wavefront of the light that has passed through the liquid crystal layer 123.

  In the liquid crystal lens 12, the optical phase difference is determined by the orientation of the liquid crystal. Further, the optical phase difference distribution changes when the method of applying a voltage to the liquid crystal layer 123 is changed. Therefore, the liquid crystal lens 12 is an optical element that can electrically control the focal length and the angle (direction) of light by the voltage applied to the liquid crystal layer 123.

  The reflector (or reflector) 13 has a reflective surface, for example, a plane mirror, and is disposed so that the reflective surface is preferably parallel to the element surface of the liquid crystal lens 12. Here, “parallel” includes not only the case where the reflecting surface of the reflector is strictly parallel to the element surface of the liquid crystal lens 12 but also the case where the reflecting surface is substantially parallel. The presence of various variations in design or manufacturing is allowed.

  In this example, the reflecting surface of the reflector 13 is a plane mirror, but it can also be a concave mirror or a convex mirror. The reflecting surface of the reflector 13 is formed of a material or roughness that causes depolarization, that is, surface treatment is performed so as to cause depolarization.

In the illuminating device 10 _A according to the first embodiment having the above-described configuration, the light emitted from the light source 11 is the forward path through which the light passes through the liquid crystal lens 12, and the light reflected by the reflector 13 passes through the liquid crystal lens 12. In this way, the liquid crystal lens 12 is passed twice in total. Thus, the light emitted from the light source 11 is emitted as illumination light after passing through the liquid crystal lens 12 a plurality of times, so that the diffusion or scattering performance of the illumination light can be enhanced. In addition, since the light source, the optical element, and the reflector have a simple configuration, the present lighting device can be provided at low cost.

Subsequently, the liquid crystal lens 12 when the OFF state and the liquid crystal lens 12 is in the ON state, the behavior of light in the illumination device 10 _A according to the first embodiment will be described with reference to FIG. In FIG. 2, (A) shows the behavior of light when the liquid crystal lens 12 is in the OFF state, and (B) shows the behavior of light when the liquid crystal lens 12 is in the ON state.

  Here, “the liquid crystal lens 12 is OFF” means a state in which no voltage is applied to the liquid crystal layer 123. The same applies to the following embodiments. “The liquid crystal lens 12 is ON” means a state in which a voltage is applied to the liquid crystal layer 123. The same applies to the following embodiments.

  When the liquid crystal lens 12 is in the OFF state, as shown in FIG. 2A, the light emitted from the light source 11 passes (transmits) through the liquid crystal lens 12 having polarization dependency, and then the reflector 13. Reflected by the reflecting surface. Here, the reflecting surface of the reflector 13 is subjected to a surface treatment so as to cause depolarization. Therefore, the light reflected by the reflecting surface of the reflector 13 is again passed (transmitted) through the liquid crystal lens 12 in a depolarized state and emitted as illumination light.

  When the liquid crystal lens 12 is in the ON state, as shown in FIG. 2B, the light emitted from the light source 11 is diffused by the liquid crystal lens 12 when passing through the liquid crystal lens 12 having polarization dependency. It becomes diffused light by the action of. This diffused light is depolarized and reflected by the reflecting surface of the reflector 13 and passes through the liquid crystal lens 12 again. At this time, the light is further diffused by the action of diffusion by the liquid crystal lens 12 and is emitted as illumination light. Then, by controlling the voltage applied to the liquid crystal layer 123 of the liquid crystal lens 12, the degree of diffusion of illumination light (diffused light) can be changed.

According to the illuminating device 10 _A according to the reflective example 1 having the above-described configuration, the light emitted from the light source 11 passes through the liquid crystal lens 12 twice in the process of being emitted as illumination light. Diffusion performance is higher than that of transmissive illumination devices. However, since the liquid crystal lens 12 has polarization dependency, the diffusion efficiency is lowered.

[Example 2]
FIG. 3 is a cross-sectional view illustrating the configuration of the illumination device according to the second embodiment. 3A is a cross-sectional view of the lighting device, and FIG. 3B is a cross-sectional view of the liquid crystal lens. The configuration of the liquid crystal lens shown in FIG. 3B is the same as that of the liquid crystal lens shown in FIG.

In FIG. 3A, the illumination device 10 _{B according to the} second embodiment includes a light source 11, a liquid crystal lens 12 that is an optical element having polarization dependency, a reflector 13, and a λ / 4 plate that is a retardation plate. 14 is provided. In this example, it is assumed that the liquid crystal lens 12 has lens characteristics that diffuse only laterally polarized light. The λ / 4 plate 14 acts to cause a phase difference of π / 2 (= 90 degrees) between orthogonal polarization components.

  The λ / 4 plate 14 is disposed between the liquid crystal lens 12 and the reflector 13 so that the element surface thereof is parallel to the element surface of the liquid crystal lens 12 and the reflection surface of the reflector 13. Here, “parallel” means that the element surface of the λ / 4 plate 14 is substantially parallel to the element surface of the liquid crystal lens 12 and the reflecting surface of the reflector 13 in addition to being strictly parallel. Including. The presence of various variations in design or manufacturing is allowed.

  The λ / 4 plate 14 is preferably a broadband retardation plate having a predetermined band, for example, a band of about 400 nm to 700 nm. By using such a broadband λ / 4 plate, a constant phase difference can be given to any wavelength, and therefore wavelength dependency can be reduced.

In the illuminating device 10 _B according to the second embodiment having the above-described configuration, the point that the light emitted from the light source 11 passes through the liquid crystal lens 12 twice is the same as in the first embodiment. In the illuminating device 10 _{B according to the} second embodiment, the λ / 4 plate 14 is disposed between the liquid crystal lens 12 and the reflector 13 so that all of the light emitted from the light source 11 is transmitted by the liquid crystal lens 12. it is possible to diffuse, it is possible to increase the diffusion performance and the diffusion efficiency of the illumination light than that of the illumination device 10 _a according to the first embodiment.

Next, the behavior of light in the illumination device 10 _{B according to the} second embodiment when the liquid crystal lens 12 is in the OFF state and when the liquid crystal lens 12 is in the ON state will be described with reference to FIG. In FIG. 4, (A) shows the behavior of light when the liquid crystal lens 12 is in the OFF state, and (B) shows the behavior of light when the liquid crystal lens 12 is in the ON state.

  When the liquid crystal lens 12 is in the OFF state, the light emitted from the light source 11 passes (transmits) through the liquid crystal lens 12 and the λ / 4 plate 14 as shown in FIG. Reflected by 13 reflecting surfaces. Here, unlike the first embodiment, the reflecting surface of the reflector 13 is not subjected to a surface treatment that causes depolarization. Accordingly, the light reflected by the reflecting surface of the reflector 13 is incident on the λ / 4 plate 14 while maintaining the polarization, passes through the liquid crystal lens 12 again, and is emitted as illumination light. Thereby, the illumination light becomes light having directivity of the light source 11.

  Next, the behavior of light when the liquid crystal lens 12 is in the ON state will be described with reference to FIG. As described above, the liquid crystal lens 12 diffuses only laterally polarized light. In FIG. 4B, the polarization state of the forward path from the light source 11 through the liquid crystal lens 12 and the λ / 4 plate 14 to the reflecting surface of the reflector 13 is indicated by a solid line with a black arrow. The polarization state of the return path reflected by the reflecting surface of the body 13 and passing through the liquid crystal lens 12 and the λ / 4 plate 14 again is indicated by a broken line with a black arrow. Here, “black arrow” means an arrow with a black triangle at the end of the line.

  When light emitted from the light source 11 enters the liquid crystal lens 12, the liquid crystal lens 12 diffuses laterally polarized light and does not diffuse longitudinally polarized light. That is, laterally polarized light is diffused when passing through the liquid crystal lens 12, and longitudinally polarized light is not diffused when passing through the liquid crystal lens 12.

  The laterally polarized light diffused by the liquid crystal lens 12 passes through the λ / 4 plate 14 and becomes left circularly polarized light by the action of the λ / 4 plate 14. The left circularly polarized light after passing through the λ / 4 plate 14 becomes right circularly polarized light by being reflected by the reflecting surface of the reflector 13, and becomes vertical polarized light by passing again through the λ / 4 plate 14. The longitudinally polarized light is not diffused when passing through the liquid crystal lens 12 and is emitted as part of the illumination light as it is vertically polarized.

  On the other hand, the longitudinally polarized light that has passed through the liquid crystal lens 12 without being diffused passes through the λ / 4 plate 14 and becomes right circularly polarized light by the action of the λ / 4 plate 14. The right-handed circularly polarized light after passing through the λ / 4 plate 14 becomes left-handed circularly polarized light by being reflected by the reflecting surface of the reflector 13, and becomes right-handed polarized light by passing through the λ / 4 plate 14 again. The laterally polarized light is diffused when passing through the liquid crystal lens 12 and is emitted as diffused light as part of the illumination light.

As is clear from the above description, according to the illuminating device 10 _B according to the second embodiment, the λ / 4 plate 14 is disposed between the liquid crystal lens 12 and the reflecting surface of the reflector 13. All of the light emitted from 11 can be diffused by the liquid crystal lens 12. Specifically, the laterally polarized light emitted from the light source 13 can be diffused in the forward path, and the longitudinally polarized light emitted from the light source 13 can be diffused in the backward path. Therefore, it is possible to improve the diffusion performance and diffusion efficiency of illumination light.

[Example 3]
FIG. 5 is a cross-sectional view illustrating the configuration of the illumination device according to the third embodiment. 5A is a cross-sectional view of the lighting device, and FIG. 5B is a cross-sectional view of the liquid crystal lens. The configuration of the liquid crystal lens shown in FIG. 5B is the same as that of the liquid crystal lens shown in FIG.

The lighting device 10 _{C according} to the third embodiment is the same as the lighting device 10 _{B according} to the second embodiment in that the light source 11, the liquid crystal lens 12, the reflector 13, and the λ / 4 plate 14 are basic components. It is. That is, it is assumed that the liquid crystal lens 12 has a lens characteristic that diffuses only laterally polarized light. The lighting device 10 _{C according to the} third embodiment stores the light source 11, the liquid crystal lens 12, the reflector 13, and the λ / 4 plate 14, which are basic constituent elements, in a package 15 to form one package. The composition is taken.

  The type of directivity of the light source 11 does not matter. It may be diffused light emitted from a point light source, or may be parallel light emitted from a surface light source. In this example, the reflecting surface of the reflector 13 is a plane mirror, but the present invention is not limited to this. The reflecting surface of the reflector 13 may be a concave mirror or may be a convex mirror.

Next, the behavior of light in the illumination device 10 _{C according to the} third embodiment when the liquid crystal lens 12 is in the OFF state and when the liquid crystal lens 12 is in the ON state will be described with reference to FIG. In FIG. 6, (A) shows the behavior of light when the liquid crystal lens 12 is in the OFF state, and (B) shows the behavior of light when the liquid crystal lens 12 is in the ON state.

The lighting device 10 _{C according to the} third embodiment has the same basic components as the lighting device 10 _{B according} to the second embodiment, and thus the behavior of light when the liquid crystal lens 12 is turned off and when the liquid crystal lens 12 is turned on is also described. Basically, it is the same as the lighting device 10 _{B according} to the second embodiment.

  That is, when the liquid crystal lens 12 is in the OFF state, the light emitted from the light source 11 passes (transmits) through the liquid crystal lens 12 and the λ / 4 plate 14 as shown in FIG. Reflected by the reflecting surface of the reflector 13. Since depolarization is not performed at the time of this reflection, the reflected light is incident on the λ / 4 plate 14 while maintaining the polarization, passes through the liquid crystal lens 12 again, and is emitted as illumination light.

When the liquid crystal lens 12 is in the ON state, the light emitted from the light source 11 is incident on the liquid crystal lens 12 as in the case of the illumination device 10 _{B according to} the second embodiment. Diffuse and do not diffuse longitudinally polarized light. The laterally polarized light diffused by the liquid crystal lens 12 becomes left circularly polarized light by passing through the λ / 4 plate 14, and then becomes right circularly polarized light by being reflected by the reflector 13. The right circularly polarized light becomes longitudinally polarized light by passing through the λ / 4 plate 14 and is emitted as part of the illumination light without being diffused by the liquid crystal lens 12.

  On the other hand, the longitudinally polarized light which has passed through the liquid crystal lens 12 without being diffused becomes right circularly polarized light by passing through the λ / 4 plate 14 and then reflected by the reflector 13 to become left circularly polarized light. Become. The left circularly polarized light becomes laterally polarized light by passing through the λ / 4 plate 14, is diffused when passing through the liquid crystal lens 12, and is emitted as part of illumination light as diffused light.

According to the illuminating device 10 _C according to the third embodiment, the components are housed in the package 15 and formed into one package, so that the apparatus main body can be made compact and the handling becomes simple. Further, as is clear from the behavior of light when the liquid crystal lens 12 is turned on / off, the ON / OFF of the liquid crystal lens 12 makes it possible to control switching of the directivity of illumination light such that the directivity is high / low. In this regard, it can be said that the same applies illumination device 10 _B according to the second embodiment.

[Example 4]
FIG. 7 is a cross-sectional view illustrating the configuration of the illumination device according to the fourth embodiment. 7A is a cross-sectional view of the lighting device, and FIG. 7B is a cross-sectional view of the liquid crystal lens. The configuration of the liquid crystal lens illustrated in FIG. 7B is the same as the configuration of the liquid crystal lens illustrated in FIG.

Lighting device 10 _D according to the fourth embodiment, the light source 11, the liquid crystal lens 12, and is the same as the illumination device 10 _A according to the first embodiment of the reflector 13 in that the basic components. The difference from the illumination device 10 _{A according} to the first embodiment is that a surface light source that emits parallel light is used as the light source 11 and two reflectors, that is, the first reflector 13 _A and the second reflector 13. _It is a point having _B.

The reflecting surfaces of the first reflector 13 _A and the second reflector 13 _B is a planar mirror. However, it is not limited to a plane mirror, and may be a concave mirror or may be a convex mirror. It does not matter whether the reflecting surfaces of the first reflector 13 _A and the second reflector 13 _B are parallel to the element surface of the liquid crystal lens 12.

However, the optical axis of the emitted light (illumination light), from the viewpoint of aligning the optical axis of light emitted from the light source 11, the reflecting surfaces of the first, second reflector 13 _A, 13 _B is It is preferably parallel to the element surface of the liquid crystal lens 12. Here, “parallel” means that each of the reflecting surfaces of the first and second reflectors 13 _A and 13 _B is substantially parallel in addition to the case where the reflecting surfaces are strictly parallel to the element surface of the liquid crystal lens 12. Including some cases. The presence of various variations in design or manufacturing is allowed.

The reflecting surfaces of the first and second reflectors 13 _A and 13 _B are formed of a material or roughness that causes depolarization, that is, surface treatment is performed to cause depolarization. . The first reflector 13 _A functions to reflect the light emitted from the light source 11 and transmitted (transmitted) through the liquid crystal lens 12 toward the liquid crystal lens 12. The second reflector 13 _B functions to reflect the light reflected by the first reflector 13 _A and transmitted (transmitted) through the liquid crystal lens 12 toward the liquid crystal lens 12.

Basic components of the illumination device 10 _D , that is, the light source 11, the liquid crystal lens 12, and the first and second reflectors 13 _A and 13 _B are provided in the package 15 as in the third embodiment. It is stored in one package. The package 15 may be a simple space, or the package 15 may be filled with resin, for example. By filling the package 15 with resin, there is an advantage that reflection at an interface, that is, a boundary surface with a component can be suppressed.

  From the viewpoint of diffusing light incident at an inclination angle with respect to the opening surface of the package 15 due to a difference in refractive index at the interface (opening surface), the package 15 is filled with, for example, a resin. Is preferred. In this example, the package 15 is filled with, for example, a resin.

A lighting device 10 _D according to Example 4 of the above arrangement, light emitted from the light source 11 passes through the liquid crystal lens 12 (transmission), 1 of the reflector 13 liquid crystal lens 12 again and is reflected by the _A pass. The light that has passed through the liquid crystal lens 12 is reflected by the second reflector 13 _B and further passes through the liquid crystal lens 12. Thereby, the light emitted from the light source 11 passes through the liquid crystal lens 12 a plurality of times in the process of being emitted as illumination light (in the optical path).

Specifically, the first of the emitted light passes through the liquid crystal lens 12 from the light source 11, and the second time first light passes through is liquid crystal lens 12 and reflected by the first reflector 13 _A, 2 The third time light is reflected by the second reflector 13 _B and passes through the liquid crystal lens 12, and passes through the liquid crystal lens 12 a total of three times. In this example, the number of reflectors is two. However, by further increasing the number of reflectors, the number of times that the light emitted from the light source 11 passes through the liquid crystal lens 12 can be further increased.

Subsequently, the liquid crystal lens 12 when the liquid crystal lens 12 when the OFF state of the ON state, the behavior of light in the illumination apparatus 10 _D according to the fourth embodiment.

The behavior of light when the liquid crystal lens 12 is in the OFF state is as shown by a one-dot chain line in FIG. That is, the parallel light emitted from the light source 11 which is a surface light source passes (transmits) through the liquid crystal lens 12 while maintaining the parallel state, and further, the liquid crystal lens with the first reflector 13 _A while maintaining the parallel state. Reflected in 12 directions.

Been parallel light reflected by the first reflector 13 _A, it passes through the left liquid crystal lens 12 maintaining a parallel state, further, in the direction of the liquid crystal lens 12 in the second reflector 13 _B while maintaining the parallel state Reflected. The parallel light reflected by the second reflector 13 _B passes through the liquid crystal lens 12 and then enters the opening surface (interface) of the package 15 perpendicularly to the optical axis of the parallel light emitted from the light source 1. Parallel light in the same optical axis direction as the direction is emitted to the outside as illumination light.

  The behavior of light when the liquid crystal lens 12 is in the ON state will be described with reference to FIG. In FIG. 8 as well, the behavior of light is indicated by a one-dot chain line as in FIG.

The parallel light emitted from the light source 11 is diffused when passing through the liquid crystal lens 12. This diffused light is reflected in the direction of the liquid crystal lens 12 by the first reflector 13 _A , and is diffused again when passing through the liquid crystal lens 12. This diffused light is reflected by the second reflector 13 _B in the direction of the liquid crystal lens 12 and further diffused when passing through the liquid crystal lens 12, and then diffused at the opening surface (interface) of the package 15 and illuminated. It is emitted to the outside as light.

According to the illuminating device _10D according to the fourth embodiment having the above-described configuration, the liquid crystal lens 12, that is, the diffusion layer is moved a plurality of times in the process (in the optical path) until the light emitted from the light source 11 is emitted as illumination light. Since it passes (transmits), it is possible to improve the diffusion performance and efficiency of illumination light. As is clear from the above description of the behavior of light, parallel light becomes illumination light when the liquid crystal lens 12 is turned off, and diffused light becomes illumination light when the liquid crystal lens 12 is turned on, so that the liquid crystal lens 12 is turned on. With / OFF, it is possible to control switching of the spread of illumination light such that the spread of illumination light is wide / narrow.

  In each of the above-described embodiments, it is also possible to adopt a configuration using a liquid lens, which has been described by taking the case of using a liquid crystal lens as an example of an optical element that diffuses or scatters light emitted from a light source.

In addition, this indication can take the following structures.
(1) light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
With
Light emitted from a light source is emitted as illumination light after passing through an optical element a plurality of times.
(2) The reflector includes at least two reflectors, a first reflector provided on one element surface side of the optical element and a second reflector provided on the other element surface side of the optical element. The lighting device according to (1), comprising:
(3) The illumination device according to (2), wherein the reflection surface of the first reflector and the reflection surface of the second reflector are parallel planes.
(4) The illumination device according to (1), wherein the reflection surface of the reflector is surface-treated so as to cause depolarization.
(5) The illumination device according to (1), including a retardation plate disposed between the optical element and the reflecting surface of the reflector.
(6) The illumination device according to (5), wherein the retardation plate is a λ / 4 plate (λ is a wavelength).
(7) The illumination device according to (6), wherein the λ / 4 plate is a broadband phase difference plate that gives a constant phase difference to a wavelength in a predetermined band.
(8) The illumination device according to any one of (1) to (4), wherein the light source, the optical element, and the reflector are housed in one package.
(9) The illumination device according to any one of (5) to (7), wherein the retardation plate is housed in one package together with the light source, the optical element, and the reflector.
(10) The illumination device according to any one of (1) to (9), wherein the optical element has polarization dependency.
(11) The illumination device according to (10), wherein the optical element is a liquid crystal lens.
(12) The liquid crystal lens includes two transparent substrates and a liquid crystal layer made of a liquid crystal material sealed between the two transparent substrates, and the lens performance is variable according to a voltage applied between the liquid crystal layers ( The lighting device according to 11).
(13) The illumination device according to any one of (1) to (9), wherein the optical element is a liquid lens.
(14) light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
In driving a lighting device comprising:
A driving method of an illuminating device that emits light emitted from a light source as illumination light after passing through an optical element a plurality of times.

10 _A , 10 _B , 10 _C , 10 _D: Illumination device, 11: Light source, 12: Liquid crystal lens, 13: Reflector, 13 _A: First reflector, 13 _B ... Second reflector, 14 ... λ / 4 plate, 15 ... Package

Claims (14)

light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
With
Light emitted from a light source is emitted as illumination light after passing through an optical element a plurality of times.   The reflector comprises at least two reflectors, a first reflector provided on one element surface side of the optical element and a second reflector provided on the other element surface side of the optical element. Item 2. The lighting device according to Item 1.   The lighting device according to claim 2, wherein the reflecting surface of the first reflector and the reflecting surface of the second reflector are parallel planes.   The lighting device according to claim 1, wherein the reflecting surface of the reflector is surface-treated so as to cause depolarization.   The illuminating device of Claim 1 which has a phase difference plate arrange | positioned between the optical element and the reflective surface of a reflector.   The lighting device according to claim 5, wherein the retardation plate is a λ / 4 plate (λ is a wavelength).   The illumination device according to claim 6, wherein the λ / 4 plate is a broadband phase difference plate that gives a constant phase difference to a wavelength in a predetermined band.   The lighting device according to claim 1, wherein the light source, the optical element, and the reflector are housed in one package.   The lighting device according to claim 5, wherein the retardation film is housed in one package together with the light source, the optical element, and the reflector.   The illumination device according to claim 1, wherein the optical element has polarization dependency.   The lighting device according to claim 10, wherein the optical element is a liquid crystal lens.   12. The liquid crystal lens has two transparent substrates and a liquid crystal layer made of a liquid crystal material sealed between the two transparent substrates, and the lens performance is variable according to a voltage applied between the liquid crystal layers. Lighting equipment.   The illumination device according to claim 1, wherein the optical element is a liquid lens. light source,
An optical element that diffuses or scatters light emitted from the light source; and
A reflector that reflects light that has passed through the optical element toward the direction of the optical element;
In driving a lighting device comprising:
A driving method of an illuminating device that emits light emitted from a light source as illumination light after passing through an optical element a plurality of times.

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