JP5417005B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device that collects and distributes output light of a light emitting element by a liquid crystal lens.

  Conventionally, as this type of lighting device, a liquid crystal lens has a plurality of pairs of transparent strip electrodes facing each other with a liquid crystal layer sandwiched therebetween, and a large strip electrode surrounds a small strip electrode when viewed from the light irradiation direction. One formed concentrically is known (see, for example, Patent Document 1). These band-like electrodes apply a voltage to each part of the liquid crystal layer to adjust the orientation of liquid crystal molecules for each part and control the refractive index. The output light of the light emitting element is irradiated through such a liquid crystal lens. Therefore, there is a possibility that unevenness of light corresponding to the electrode pattern of the strip-shaped electrode occurs in the irradiation light.

  Therefore, in order to suppress light unevenness, it is conceivable that the width of the strip electrode is reduced to increase the number of the strip electrodes, and the strip electrode has a fine structure. However, with this method, the formation of the strip-shaped electrode becomes complicated, and the manufacturing cost may increase.

JP 2005-317879 A

  The present invention has been made to solve the above-described problems, and in an illumination device that controls light distribution using a liquid crystal lens, it suppresses the unevenness of light emitted from the liquid crystal lens while suppressing the manufacturing cost. An object of the present invention is to provide a lighting device that can perform the above-described operation.

In order to achieve the above object, the invention of claim 1 is a lighting device comprising: a light emitting element; and a liquid crystal lens that collects and distributes output light from the light emitting element. Each of the plurality of liquid crystal lenses is disposed so as to overlap with each other , two transparent substrates, a liquid crystal layer sealed between the transparent substrates, and a voltage applied to the liquid crystal layer across the liquid crystal layer. An electrode part that controls the orientation of liquid crystal molecules by controlling, the electrode parts having a plurality of transparent strip-like electrodes that are different in size and formed in a similar shape when viewed from the light irradiation direction. The large strip-shaped electrode has an electrode pattern arranged so as to surround the small strip-shaped electrode, and each strip-shaped electrode of the liquid crystal lens in the foreground when viewed from the light irradiation direction is behind the liquid crystal The lenses adjacent to each other in the lens Across the boundary between Jo electrodes have covered the belt-shaped electrode by a width half the at least one of said plurality crystal lenses are those diffusing material for diffusing the transmitted light is sealed.

According to a second aspect of the invention, in the illumination apparatus according to claim 1, for each of the liquid crystal lens, wherein the electrode pattern, their center position in accordance with the desired light irradiation direction, coincident with the optical axis of the light emitting element in which are arranged so as to be displaced or in one direction such that.

According to the first aspect of the present invention, when viewed from the light irradiation direction, each band-like electrode of the front liquid crystal lens and each band-like electrode of the back liquid crystal lens are separated from each other, and the direction of the optical path of the transmitted light for each overlapping portion Therefore, it is possible to obtain a pseudo fine configuration as in the case where a band-like electrode having a narrow width is disposed at each of those portions. For this reason, the light unevenness of the irradiation light according to the electrode pattern of a strip | belt-shaped electrode can be suppressed. Moreover, since it is not necessary to actually make the strip-like electrode have a fine structure in order to suppress the light unevenness, the manufacturing cost can be suppressed. Further, since the light transmitted through the liquid crystal lens is diffused by the diffusing material, the light unevenness can be further suppressed.

  According to invention of Claim 2, since it can irradiate light in a desired direction, effect illumination can be performed.

The cross-sectional block diagram of the illuminating device which concerns on one Embodiment of this invention. The electrical block diagram of the said apparatus. FIG. 3 is a cross-sectional configuration diagram of two liquid crystal lenses stacked in the apparatus. (A) is a perspective view of the electrode part of each said liquid-crystal lens, (b) is a top view of each electrode part. The circuit block diagram of each said electrode part and a control circuit. The figure which shows the applied voltage and effective birefringence of each site | part of the said liquid-crystal lens. (A) is a diagram showing the pseudo lens thickness of the front liquid crystal lens when viewed from the light irradiation direction of the two sheets, (b) is a diagram showing the pseudo lens thickness of the liquid crystal lens behind it, and (c) is the above diagram. The figure which shows pseudo lens thickness when two liquid crystal lenses are piled up. The perspective view of the street lamp to which the said apparatus is applied. (A) is a top view of the electrode part of the liquid crystal lens of the illuminating device which concerns on the modification of the said embodiment, (b) The top view which shows the brightness distribution of the light irradiation area | region by the said apparatus. (A) is a top view of the electrode part of the liquid crystal lens of the illuminating device which concerns on another modification different from the above, (b) The top view which shows the brightness distribution of the light irradiation area | region by the said apparatus.

  Hereinafter, an illumination device according to an embodiment of the present invention will be described with reference to the drawings. FIG.1 and FIG.2 shows the structure of the illuminating device which concerns on this embodiment. The lighting device 1 includes a housing 2, a light emitting element 3 housed in the housing 2, two liquid crystal lenses 4 a and 4 b that collect and distribute output light from the light emitting element 3, and the light emitting element 3. A lighting circuit 5 that controls lighting, a liquid crystal lens control circuit (hereinafter referred to as a control circuit) 6 that controls driving of the liquid crystal lenses 4a and 4b, and a reflection that reflects output light from the light emitting element 3 toward the liquid crystal lenses 4a and 4b. And a plate 7. The housing 2 has a light exit port 21.

  The liquid crystal lenses 4 a and 4 b are overlapped and attached to the housing 2 so as to close the light emission port 21. The liquid crystal lens 4a is in front of the light irradiation direction, and the liquid crystal lens 4b is behind it. The number of liquid crystal lenses is not limited to two and may be a plurality. The control circuit 6 controls the focal length of the light and the light irradiation region by controlling the voltage applied to the liquid crystal layers in the liquid crystal lenses 4a and 4b, thereby performing light distribution control.

  The reflecting plate 7 has a bowl shape whose diameter is increased toward the light exit port 21 in the housing 2, and the light emitting element 3 is disposed on the inner bottom portion of the reflecting plate 7. Power is supplied to the light emitting element 3, the liquid crystal lenses 4a and 4b, the lighting circuit 5 and the control circuit 6 from a commercial power source. The lighting circuit 5 and the control circuit 6 are attached to appropriate positions of the housing 2.

  FIG. 3 shows the configuration of the liquid crystal lenses 4a and 4b, and FIGS. 4A and 4B show the configuration of the electrode portions of the liquid crystal lenses 4a and 4b. Each of the liquid crystal lenses 4 a and 4 b includes two transparent substrates 41, a sealing material 42 for containing a liquid crystal material between the transparent substrates 41, and a liquid crystal layer made of a liquid crystal material sealed between the transparent substrates 41. 43 and an electrode portion 44 for applying a voltage to the liquid crystal layer 43. The electrode unit 44 controls the orientation of the liquid crystal molecules 43 a by controlling the applied voltage under the control of the control circuit 6, and thus adjusts the refractive index of the liquid crystal layer 43.

  The electrode portion 44 includes a transparent center electrode 45 and a strip electrode 46 (hereinafter collectively referred to as electrodes 45 and 46) that face each other across the liquid crystal layer 43. The center electrode 45 has a substantially disk shape, and the strip electrode 46 is disposed so as to surround the outer periphery of the center electrode 45, and five pairs are provided as one pair in the upper and lower sides. The band-like electrodes 46 are different in size for each pair, and are formed in a substantially C-shaped similar shape when viewed from the light irradiation direction. These strip electrodes 46 form an electrode pattern in which the large strip electrode 46 is disposed so as to surround the small strip electrode 46. The electrodes 45 and 46 can be made of an ITO transparent conductive film, and an insulating member is inserted between the electrodes 45 and 46. Each of the electrodes 45 and 46 has an alignment film on the upper and lower opposing surfaces, and these alignment films make the main axis of the liquid crystal molecules 43a substantially horizontal or slightly oblique in a state where no voltage is applied. The number of electrodes 46 is not limited to the above, and may be a plurality of pairs.

  Each strip electrode 46 of the liquid crystal lens 4a covers the boundary L1 between the electrodes 45 and 46 of the liquid crystal lens 4b, and further covers the insulating member existing therebetween, and the cross section of the strip electrode 46 of the liquid crystal lens 4b. They are arranged in a staggered manner. The electrodes 45 and 46 of the liquid crystal lens 4a are smaller in size than those of the liquid crystal lens 4b. Each strip electrode 46 of the liquid crystal lens 4a desirably covers half of the width of the strip electrodes 46 adjacent to each other in the liquid crystal lens 4b across the boundary L1. The band widths of the respective band electrodes 46 of the liquid crystal lenses 4a and 4b may be the same or different. It is desirable that the cutout portion of the strip electrode 46 does not overlap vertically in order to prevent the portion from being projected onto the light irradiation surface.

  In any of the liquid crystal lenses 4a and 4b, the center position of each of the electrodes 45 and 46 is a position corresponding to a desired light irradiation direction. In the present embodiment, the light irradiation direction is the direction of the optical axis C1 of the light emitting element 3, and the center positions of the electrodes 45 and 46 coincide with the optical axis C1.

  The electrode portion 44 has an extraction electrode 47 in the C-shaped cutout portion of the strip electrode 46, and the extraction electrode 47 connects the electrodes 45, 46 and the control circuit 6. Each of the electrodes 45 and 46 is controlled by the control circuit 6, and each applies a different voltage to the liquid crystal layer 43 to change the refractive index for each part, thereby providing the liquid crystal layer 43 with a lens function.

  FIG. 5 shows a circuit configuration of the electrode unit 44 and the control circuit 6 of each of the liquid crystal lenses 4a and 4b. In the drawing, only the electrodes 45 and 46 disposed on the upper side of the liquid crystal layer 43 in each electrode portion 44 are illustrated. Here, the extraction electrodes 47 extracted from the electrodes 45 and 46 are referred to as extraction electrodes 47a to 47e in this order from the center electrode 45, which is the extraction source, to the outermost strip electrode 46. All of the electrode portions 44 are referred to as such.

  The control circuit 6 includes a variable voltage source 61 and a voltage dividing resistor 62 to which the output voltage of the variable voltage source 61 is applied at both ends. The variable voltage source 61 may be either an AC power source or a DC power source. One output terminal of the variable voltage source 61 is connected to a reference contact 62a having a reference potential. Extraction electrodes 47 a to 47 e are connected to the voltage dividing resistor 62.

The lead electrodes 47a to 47e of the liquid crystal lens 4a and those of the liquid crystal lens 4b are respectively connected in parallel. In any of the liquid crystal lenses 4a and 4b, the extraction electrode 47a is connected to the reference contact 62a, and the extraction electrodes 47b to 47e are connected to predetermined points of the voltage dividing resistor 62 and set to different potentials. . Although not shown, the electrodes 45 and 46 below the liquid crystal layer 43 are connected to the reference contact 62a. With such a circuit configuration, the electrodes 45 and 46 of the liquid crystal lens 4a and the electrodes 45 and 46 of the liquid crystal lens 4b are set to the same potential in a one-to-one correspondence. In each of the liquid crystal lenses 4a and 4b, the potentials of the electrodes 45 and 46 are set to different predetermined values. Here, the voltages applied by the electrodes 45 and 46 are referred to as V _{1 to} V _{5 in} order from the innermost circumference to the outermost circumference.

FIG. 6 shows the relationship between the voltages V _{1 to} V ₅ applied to each part of the liquid crystal lens 4a and the effective birefringence Δn of each part. The effective birefringence Δn is an optical path difference between the light transmitted through the liquid crystal lens 4a and the ordinary light and the extraordinary light. The figure shows an ideal characteristic Lv of the applied voltage V and an ideal characteristic Ln of the effective birefringence Δn. The ideal characteristic Ln indicates a characteristic for causing the liquid crystal lens 4a to function as a convex lens, and the ideal characteristic Lv indicates an applied voltage characteristic for realizing the ideal characteristic Ln. The ideal characteristic Ln is a paraboloidal characteristic in which Δn is highest at the center of the lens and decreases toward the outer periphery. The ideal characteristic Lv is a characteristic in which the applied voltage gradually increases from the lens center toward the outer periphery. V ₁ is set to substantially zero.

The effective birefringence Δn varies according to the inclination of the main axis of the liquid crystal molecules 43a, and Δn increases as the main axis approaches horizontal. The lens center, V ₁ is substantially zero, since the orientation of the liquid crystal molecules 43a becomes substantially horizontal, [Delta] n is the maximum. Further, V _{2 to} V ₅ gradually increase from the center of the lens toward the outer periphery, so that the direction of the main axis of the liquid crystal molecules 43a gradually approaches substantially vertical, and Δn decreases. With such a setting, Δn takes a value along the ideal characteristic Ln, and the liquid crystal lens 4a functions as a normal convex lens having a substantially uniform refractive index with a thickness decreasing from the approximate center to the periphery. Although only the liquid crystal lens 4a has been described here, the liquid crystal lens 4b has an effective birefringence Δn distribution equivalent to that of the liquid crystal lens 4a, and thus the description thereof is omitted.

  FIGS. 7A to 7C show pseudo lens thicknesses when only the liquid crystal lens 4a, only the liquid crystal lens 4b, and when the liquid crystal lenses 4a and 4b are overlapped as in the present embodiment. The pseudo lens thickness is a value corresponding to the lens thickness when the liquid crystal lens is replaced with a normal lens.

  As shown in FIG. 7A, since the liquid crystal lens 4a functions as a convex lens, the pseudo lens thickness becomes maximum at the center of the liquid crystal lens 4a and decreases from the lens center toward the outer periphery. The decreasing method is a stepped shape corresponding to the position and width of the strip electrode 46. As shown in FIG. 7B, the pseudo lens thickness of the liquid crystal lens 4b also decreases stepwise from the center of the lens toward the outer periphery. However, the electrodes 45 and 46 of the liquid crystal lens 4b are different from those of the liquid crystal lens 4a, respectively. Since the dimension is large, each decreasing position is shifted in the outer circumferential direction.

  As shown in FIG. 7C, the total pseudo lens thickness of the present embodiment in which the liquid crystal lenses 4a and 4b are overlapped is obtained by superimposing the pseudo lens thickness characteristics of FIGS. 7A and 7B. It becomes the highest at, and as it goes to the outer periphery, it decreases with a larger number of steps and a smaller amount of change. The combination of the liquid crystal lenses 4a and 4b is closer to a normal smooth convex lens than in the case where each of the liquid crystal lenses 4a and 4b is a single unit. Therefore, the optical path of transmitted light can be adjusted more finely.

  FIG. 8 shows a street lamp using the lighting device 1. The street light 8 includes a support column 81 that supports the lighting device 1 at the upper end, and the lighting device 1 faces obliquely downward. In the illuminating device 1, since the liquid crystal lenses 4a and 4b function as convex lenses having a substantially centered vertex, the focal point P1 is located at the substantially center of the light irradiation region A1, the vicinity thereof becomes brightest, and becomes darker toward the outer periphery. Become.

  In the illuminating device 1 of the present embodiment configured as described above, the respective strip-like electrodes 46 of the front liquid crystal lens 4a and the respective strip-like electrodes 46 of the rear liquid crystal lens 4b are separated from each other when viewed from the light irradiation direction. The direction of the optical path of the transmitted light can be adjusted for each overlapping portion. Therefore, it is possible to obtain a pseudo fine configuration as in the case where the band-like electrode 46 having a narrow width is disposed at each of these portions. For this reason, the light unevenness of the irradiation light according to the electrode pattern of the strip electrode 46 can be suppressed. Moreover, since it is not necessary to actually make the strip electrode 46 have a fine structure in order to suppress the light unevenness, the manufacturing cost can be suppressed.

  Moreover, since the center position of each electrode 45 and 46 of liquid crystal lens 4a, 4b is a position according to a desired light irradiation direction, light can be irradiated to a desired direction and production illumination can be performed. Further, since the liquid crystal lenses 4a and 4b are overlapped, the total lens thickness is increased, so that the focus control range can be widened.

  Next, an illumination device according to a first modification of the above embodiment will be described with reference to the drawings. FIG. 9A shows an electrode portion 44 of the illumination device according to this modification. The electrode portion 44 has an electrode pattern different from that of the above embodiment. The center positions of the electrode patterns of the electrodes 45 and 46 are arranged so as to be displaced in one direction according to the desired light irradiation direction. The center position of each strip electrode 46 gradually shifts in one direction from the outermost one to the innermost one. The cutout portion for disposing the extraction electrode 47 in the strip electrode 46 is formed in the displacement direction in order to shorten the length of the extraction electrode 47.

  FIG.9 (b) shows the light irradiation area | region A1 when using the illuminating device of this modification instead of the illuminating device 1 of the said embodiment in the above-mentioned street light 8 (refer FIG. 8). Since the center positions of the electrodes 45 and 46 are displaced in one direction, the focal point P1 and the brightest region in the vicinity thereof are displaced in one direction as compared with FIG.

  In this modification, since the center position of the electrode pattern of each electrode 45, 46 is displaced in one direction according to the desired light irradiation direction, it is possible to irradiate the light in the desired direction, and the effect illumination It can be performed.

  Next, an illumination device according to a second modification of the above embodiment will be described with reference to the drawings. FIGS. 10A and 10B show an electrode portion 44 of a lighting device according to this modification and a light irradiation region A1 by the device. The electrode pattern of the electrode portion 44 is further different from that of the first modification. In the electrode pattern of this modification, the center electrode 45 is formed in a substantially rectangular shape when viewed from the light irradiation direction, and the strip electrode 46 is formed in a similar shape of a rectangular frame surrounding the center electrode 45 and partially cut away. Yes. When the lighting device of this modification is used for the street lamp 8 (see FIG. 8) described above, the light irradiation region A1 has a rounded rectangular shape.

  Next, a third modification of the above embodiment will be described. The illustration of this modification is omitted, and FIG. 3 is used. In this modification, a diffusing material that diffuses transmitted light is enclosed between the transparent substrates 41 in addition to the liquid crystal material. This diffusing material is assumed to have a refractive index lower than that of a liquid crystal material such as silicon resin powder. The shape of the diffusion material is preferably a true sphere. When the size of the diffusing material is approximately 2 [μm], the diffusion effect is large with respect to light having a wavelength of approximately 400 [nm], and when the size is approximately 8 [μm], the wavelength is approximately 600. The diffusion effect is large for [nm] light. Therefore, the shape of the diffusing material is selected according to the wavelength of the output light of the light emitting element 3. In this modification, the light transmitted through the liquid crystal lenses 4a and 4b is diffused by the diffusing material, so that the light unevenness can be further suppressed.

  In addition, this invention is not limited to the structure of said embodiment, A various deformation | transformation is possible according to a use purpose. For example, the strip electrode 46 may not be formed in a C shape when viewed from the light irradiation direction, but may be formed in a concentric shape without a notch.

DESCRIPTION OF SYMBOLS 1 Illuminating device 3 Light emitting element 4a, 4b Liquid crystal lens 41 Transparent substrate
43 Liquid crystal layer 44 Electrode portion 46 Strip electrode L1 boundary

Claims (2)

In an illuminating device comprising: a light emitting element; and a liquid crystal lens that collects and distributes output light from the light emitting element.
A plurality of the liquid crystal lenses are arranged so as to overlap,
Each of the plurality of liquid crystal lenses includes two transparent substrates, a liquid crystal layer sealed between the transparent substrates, and a voltage applied to the liquid crystal layer with the liquid crystal layer interposed therebetween, thereby controlling liquid crystal molecules. An electrode part for controlling the orientation,
The electrode section has a plurality of transparent strip electrodes that are different in size from each other and formed in a similar shape when viewed from the light irradiation direction, and the large strip electrode is disposed so as to surround the small strip electrode. Electrode pattern,
Each strip electrode in front of the liquid crystal lens when viewed from the light irradiation direction is not covered with belt-like electrodes each width half across the boundary between the strip electrodes adjacent to each other in the liquid crystal lens located behind,
At least one of the plurality of liquid crystal lenses is filled with a diffusing material that diffuses transmitted light .   For each of the liquid crystal lenses, the electrode patterns are arranged such that their center positions coincide with the optical axis of the light emitting element or are displaced in one direction according to a desired light irradiation direction. The lighting device according to claim 1, wherein

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